Commissioning plan for gas fractionation unit

Thread Content

Table of Contents
Chapter 1 Introduction... 4
1.1 General Principles for Commissioning... 4
1.2 Scale of the Facility... 5
1.3 Composition of the Facility... 5
1.4 Main Operating Conditions... 5
1.5 Description of the Process Flow... 6
1.6 Brief Overview of Auxiliary Processes... 7
Chapter 2 Preparations for Feedstock Introduction and Commissioning... 8
2.1 Conditions Required for Commissioning... 8
2.1.1 Completion of intermediate project handovers... 8
2.1.2 Completion of joint commissioning... 9
2.1.3 Completion of personnel training... 9
2.1.4 Implementation of all production management systems... 9
2.1.5 Delivery of the start-up operation plan to production staff... 10
2.1.6 All utility systems are fully operational and capable of meeting the requirements for the process commissioning of the combined facility... 10
2.1.7 All raw materials, auxiliary materials, spare parts, tools, etc. are fully prepared and in place... 10
2.1.8 Preparation work for chemical analysis is completed... 11
2.1.9 Safety, fire protection, and first-aid systems are in place... 11
2.1.10 The production scheduling system is operating normally... 12
2.1.11 Preparation work for the process of the combined facility and confirmation of commissioning conditions have been completed... 12
2.1.12 Measures for ensuring continuous operation have been put in place... 12
2.1.13 On-site security measures have been implemented... 13
2.2 Comprehensive Quality Inspection... 13
2.2.1 Inspection of towers... 13
2.2.2 Heat exchange equipment... 13
2.2.3 Pumps... 13
2.2.4 Process pipelines... 14
2.2.5 Safety facilities... 14
2.2.6 Instruments... 15
2.2.7 Utility systems... 15
2.2.8 Blind flanges... 15
Chapter 3 Options for Introducing Steam, Circulating Water, Nitrogen, and Purified/Unpurified Air... 15
3.1 Purpose... 15
3.2 Introduction of 1.0 MPa steam... 16
3.2.1 Requirements for introducing 1.0 MPa steam... 16
3.2.2 Process flow for introducing 1.0 MPa steam... 16
3.3 Introduction of circulating water... 17
3.3.1 Requirements for introducing circulating water to the facility... 17
3.3.2 Process flow for introducing circulating water... 17
3.4 Introduction of nitrogen... 17
3.4.1 Requirements for introducing nitrogen... 17
3.4.2 Process flow for introducing nitrogen... 18
3.5 Introduction of instrument air... 18
3.6 Introduction of unpurified air... 18
Chapter 4 Steam Purging Plan... 18
4.1 Purpose of purging... 18
4.2 Conditions required for purging... 19
4.3 Inspection or re-inspection of the entire facility according to relevant standards... 19
4.4 Preparations for purging... 19
4.5 Principles of purging... 20
4.6 Specific requirements and precautions for purging... 21
4.7 Purging medium... 22
4.8 Acceptance criteria... 22
4.9 Purging process... 22
4.9.1 Purging process for the raw material and liquefied gas storage areas... 23
Chapter 5 Water Flooding and Washing Plan... 24
5.1 Individual unit testing... 24
5.1.1 Purpose of individual unit testing... 24
5.1.2 Preparations before testing... 24
5.1.3 Requirements for testing... 25
5.1.4 Inspection... 25
5.2 Water washing... 25
5.2.1 Purpose of water washing... 25
5.2.2 Conditions required for water washing... 25
5.2.3 Principles of water washing... 26
5.2.4 Precautions for water washing... 26
5.2.5 Water washing process... 26
5.3 Water flooding... 26
5.3.1 Purpose of water flooding... 26
5.3.2 Preparations before water flooding... 27
5.3.3 Precautions for water flooding... 27
5.3.4 Water flooding process... 28
Chapter 6 Facility Airtightness Test Plan... 28
6.1 Purpose of airtightness testing... 28
6.2 Technical requirements for airtightness testing... 28
6.3 Preparations before airtightness testing... 29
6.4 Division of the airtightness test system... 29
6.5 Methods and steps for airtightness testing... 29
6.6 Requirements for airtightness testing... ... 30 6.7 Safety precautions for airtightness... 31 Chapter 7 Nitrogen displacement plan... 31 7.1 Purpose of nitrogen displacement... 31 7.2 Safety precautions for nitrogen displacement... 31 7.3 Criteria for successful nitrogen displacement... 31 7.4 Procedures for nitrogen displacement... 32 7.5 Nitrogen displacement process... 32 Chapter 8 Trial operation plan with liquefied gas feed... 32 Chapter 9 Emergency response to accidents... 32 Chapter 1 Introduction The 40×104t/a gas fractionation unit, from its construction through the commissioning of all processes, until the production of qualified products such as propylene, mixed C4 hydrocarbons, and commercial propane. To lay the foundation for stable operation prior to production assessments, it is essential during the feed-in commissioning phase to ensure that the commissioning process is uninterrupted and that no major accidents occur. Best wishes for a successful first feed-in commissioning. Feed-in commissioning should adhere to high standards and strict requirements, be carefully organized, and the “three spirits” (the spirit of overall consideration, the spirit of perseverance, and the spirit of science) should be upheld. The principle of “five no-starts” should be followed: do not start the operation if the conditions are not met, if the procedures are unclear, if supervision is absent, if problems have not been resolved, or if safety, health, and environmental protection facilities are not in operation. The “seven adherences” should also be observed: adhere to the quality requirements for various raw materials and fuels; adhere to engineering quality standards, maintenance standards, and regulatory standards during commissioning; ensure strict organization of the commissioning process as well as compliance with commissioning and technical plans; enforce job standards and procedural rules to regulate employees’ behavior; carry out thorough inspections and verifications during feed-in commissioning; apply the principle of “no letting go of any accident”; and ensure that safety and health facilities are in good working condition. 1.1 General Provisions for Commissioning 1.1.1 The company and the grassroots production units must establish production preparation teams at the beginning of the project construction, responsible for carrying out all necessary production preparation tasks to meet the requirements of commissioning and production. Its main leader must oversee this work from the start of construction to ensure that project development is linked to production. 1.1.2 In addition to being familiar with the design documents, mechanical, instrumentation, and electrical specifications, as well as the construction and acceptance standards, the general contractor must also be aware of the production process flow in order to ensure that the project quality and schedule meet the requirements for commissioning. 1.1.3 The installation progress of the construction must be completed on schedule, in accordance with the control points specified in the overall construction plan. The project quality must meet the requirements of relevant standards and specifications, as well as the demands of commissioning. 1.1.4 The design representative must be familiar with mechanical properties as well as construction and acceptance specifications and other relevant requirements. The design documents must meet the requirements of pre-commissioning. During the construction process, the contractor must, in accordance with the requirements of the design specifications, process flow diagrams, and construction drawings, provide interfaces for tasks such as purging, cleaning, and displacement; properly install temporary components and clean the pipelines to create the conditions necessary for pre-commissioning. 1.1.5 The commissioning work must strictly follow the procedures specified in the overall commissioning plan; it is strictly prohibited to proceed to the next stage of commissioning if the previous stage was not completed successfully. 1.1.6 Before the commissioning process begins, the conditions specified in the Interim Provisions on Commissioning Work for Large and Medium-Sized Petrochemical Construction Projects must be met ； The test run must include everything specified in the design documents ； The test results must meet the specified standards. 1.1.7 During the chemical feeding commissioning, all interconnected production units must have the conditions necessary for sequential commissioning. 1.1.8 The chemical feeding commissioning can only begin after it has been inspected and approved by the company’s relevant department for the corresponding plan. 1.1.9 When an accident or malfunction occurs during the testing process, it is necessary to immediately identify the cause and take measures to resolve it; otherwise, further testing is strictly prohibited. 1.1.10 The electricity, water, fuel gas, fuel oil, steam, vulnerable spare parts required for the pre-commissioning, various chemicals not included in the construction budget, various lubricants and greases, as well as the materials needed for chemical feeding during commissioning and production testing, shall be ensured and supplied by the Production and Operation Department and the E-commerce Department. 1.1.11 An intermediate handover shall be carried out once a single project or part of the installation is completed, and after the internal processing of the piping systems and equipment, as well as the electrical and instrumentation adjustments, have been finished and the individual units have passed testing; an overall project handover shall take place after the joint testing of all installations is successful; a certificate of compliance shall be issued upon completion of the chemical feeding tests; and a production assessment report shall be prepared after the production evaluation is done, to be submitted to the company’s relevant management department. 1.1.12 Environmental protection projects must undergo commissioning in parallel with the production units. The treatment of waste liquids, waste gases, and waste residues generated during the testing at various stages must meet **the specified emission standards**. 1.1.13 The responsibility allocation for the pre-commissioning test shall be carried out in accordance with the company’s overall commissioning plan. 1.1.14 Chemical feeding commissioning should be carried out away from the severe cold season; otherwise, appropriate anti-freezing and cold-protection measures must be taken. 1.1.15 After the handover of the project, the general contractor shall remain responsible for the construction quality until the end of the construction quality warranty period specified in the contract; the supplier shall assume responsibility during the machinery warranty period stipulated in the order contract. 1.2 Plant scale ⑴ Nominal plant capacity: 400,000 tons per year, which is equivalent to 47,619 kg/h ； Actual capacity: 351,800 tons per year, which is equivalent to 41,881 kg/h. ⑵Annual operating hours: 8,400 hours. ⑶Operational flexibility: 60–110%. ⑷Product portfolio: Mainly produces propylene for polymerization, commercial propane, and C4 fraction products. 1.3 Device Composition The process of the gas fractionation unit mainly consists of three parts: propane removal, ethane removal, and propylene-propane separation. It consists of four distillation columns along with the corresponding systems for reboiling, condensing, and product cooling. Among them: 9 containers ； 36 heat exchangers (air coolers) ； 2 coagulators ； 14 pump units. 1.4 Main Operating Conditions The main operating conditions of the gas fractionation unit are shown in the table below. 1.5 Process Flow Description The desulfurized liquefied petroleum gas coming from the catalytic cracking unit is subjected to cascade control based on flow rate and liquid level; after dehydration through the feed coalescing filters (1218-M-101A/B, 1218-M-102A/B), it enters the raw material buffer tank (1218-D-101). It is then pumped out by the depropanization tower feed pump (1218-P-101A/B), and under cascade control based on liquid level and flow rate, it exchanges heat with C4 components in the depropanization tower feed heat exchanger (1218-E-101) before entering the depropanization tower (1218-C-101). The C2 and C3 components are distilled from the tower top; after being condensed in the propane removal tower top air cooler (1218-A-101A～F), they enter the propane removal tower top reflux tank (1218-D-102). The tower top is controlled by gas-phase thermal bypass pressure, while the reflux tank is controlled by non-condensable gas pressure. Part of the condensate is drawn off by the depropanization reflux pump (1218-P-102A/B) under flow control, and is returned to the top of the depropanization column as depropanization reflux ； Another portion is drawn off by the deethanizer feed pump (1218-P-103A/B), using cascade control of level and flow, and sent to the deethanizer (1218-C-102) as feed. The C4 fraction is cooled successively through the depropanization tower feed heat exchanger (1218-E-101) and the C4 fraction cooler (1218-E-106) starting from the bottom of the depropanization tower, and then sent to the MTBE unit as a raw material for that facility. The C4 component separation unit employs a cascade control system of hydraulic control and flow control. The reboiler of the depropanization tower (1218-E-103) uses the top recycle stream from the heavy oil catalytic unit as a heat source, with the flow rate of this catalytic top recycle being controlled via cascade control in relation to the bottom temperature of the tower. The vapor from the top of the deethanizer tower (1218-C-102) is partially condensed in the deethanizer top condenser-cooler (1218-E-104A/B) before entering the deethanizer reflux tank (1218-D-103); the pressure at the top of the tower is controlled via a vapor outlet line. The non-condensable gases in the reflux tank are mainly composed of propylene and ethane; after pressure regulation by a pressure control valve, they are sent to the outlet of the catalytic unit’s compressor or to the fuel gas network. The liquid phase in the reflux tank is pumped out by the deethanizer reflux pump (1218-P-104A/B), and through cascade control of level and flow rate, it is all sent back to the top of the deethanizer as reflux. The C3 fraction at the bottom of the tower enters Propylene Column-1 (1218-C-103) under its own pressure, following flow and level cascade control, from the bottom of the deethanization tower. The deethanizer reboiler (1218-E-105) uses hot water from a catalytic unit as the heat source, with the temperature of this hot water being controlled via cascade control based on both the bottom temperature of the tower and its flow rate. Due to the high precision requirements for separation, the propylene column has a large number of tray levels; it operates in two columns in series, with the first column being Propylene Column-1 and the second column being Propylene Column-2 (1218-C-104). The bottom of Propylene Column-1 is equipped with a reboiler (1218-E-107A/B), which uses hot water from the catalytic unit as a heat source; the temperature of this hot water is controlled via cascade control using both the column bottom temperature and its flow rate. The propane product at the bottom of Propylene Column-1 is pumped out by the propane pumps (P-107A/B), cooled in the propane cooler (E-108), and then sent to the storage tank area as propane product, with cascade control based on level and flow rates. The gas phase discharged from the top of Propylene Column-1 enters the lower part of Propylene Column-2 under its own pressure via pipes. The liquid at the bottom of Propylene Column-2 is pumped out by the intermediate pump of the propylene column (P-106A/B) and sent back to the top of Propylene Column-1 as reflux, with cascade control based on flow rate and liquid level. The vapor from the top of Propylene Column-2 is condensed in the column top air cooler (A-102A～T) and then enters the propylene reflux tank (D-104). The pressure at the top of the propylene column is controlled via a gas-phase thermal bypass, while the pressure in the reflux tank is controlled by the pressure of non-condensable gases. The liquid in the propylene reflux tank is pumped out by the propylene reflux pumps (P-105A/B) and then divided into two streams: one of these streams is sent back to the top of Propylene Column-2 as reflux, with flow control applied ； The other portion is used as an acrylic product; after being cooled by the acrylic cooler (E-110), it is sent to the storage tank area as raw material for the polypropylene plant, with cascade control based on liquid level and flow rate. The purity of propylene products is determined through online analysis, while the composition of raw materials and other materials that require analysis is determined through manual analysis. 1.6 Brief description of auxiliary processes: The utility systems involved in this device include: circulating water, hot water, fresh water, high-pressure fire water, low-pressure steam at 1.0 MPa(g), catalytic top circulation, nitrogen at 0.8 MPa(g), purified compressed air, and unpurified compressed air. This unit uses low-pressure steam at 1.0 MPa(g) from the system pipeline network for fire suppression purposes as well as for purging during startup and shutdown operations. According to the overall process arrangement, a hot water station is installed in the catalytic unit. This unit uses hot water at 100°C generated by the catalytic unit as a heat source for the deethanizer reboiler (1218-E-105) and the propylene column reboilers (1218-E-107A/B). The used water at 75°C returns to the hot water station of the catalytic unit via a backflow device driven by residual pressure. A connecting line is installed between the inlet and outlet main pipes for hot water within the gas separation unit, and a two-position on-off valve is used to minimize the impact of variations in the hot water consumption of the gas separation unit on the pressure in the hot water piping network. In winter, hot water heating is used to heat the water distribution packs and drainage pipelines of various containers. This unit uses system fresh water as the production water and startup flushing water within it. This device uses purified compressed air, which has been buffered, regulated in pressure, and dehydrated within the first combined unit, as the air supply for its instruments. This device introduces unpurified compressed air from the system pipeline network for use at the utility station. This unit introduces 0.8MPa(g) nitrogen from the system pipeline network, which, after pressure regulation, is used for purging and displacing process pipelines and equipment, sealing pumps, and purging flare lines. This unit introduces 4.0 MPa(g) nitrogen from the system pipeline network, which is then regulated in pressure within this unit for use in the airtightness testing of process pipelines and equipment. All process materials in this unit (liquefied petroleum gas, materials extracted during shutdowns, vent gases, fuel gas, oily wastewater, etc.) are discharged in a sealed manner. The discharge from the pressure control valves of each container in this device is combined and fed into the system’s 0.45 MPa(g) fuel gas pipeline network. The flare gas from the safety valve outlet, the exhaust gas after the on-line analysis instruments, and other such emissions are collected together and then discharged into the plant’s flare gas tank (1218-D-105). The main torch gas pipeline inside the unit is purged with nitrogen. The nitrogen seal exhaust gases from each pump, along with the flare gases emitted, are combined and then discharged into the flare gas tank (1218-D-105) via the main flare pipe within the plant. During normal production, the water separation from each liquefied gas container is carried out manually and in a sealed manner, and after being collected, it is discharged into the flare tank (1218-D-105) within the facility. The lower part of the flare gas tank (1218-D-105) and the exterior of the water separator are equipped with an external coil heating system. This system takes into account the conditions under which the plant needs to evacuate gas urgently in case of an accident; hot water is used to heat the water and thereby remove volatile hydrocarbons dissolved in it. The water from the flare gas tank is manually drained through a dehydrator. To prevent accidental release of liquefied hydrocarbons, this water must be directed into a sealed container for centralized recovery and treatment throughout the plant. Wastewater from startup and shutdown is discharged into the oil-containing wastewater main pipe within the unit, from where it flows out of the unit and into the plant’s overall oil-containing wastewater treatment system. The flare gas in the flare gas tank is discharged to the system’s 0.06 MPa(g) flare network. The material extracted during shutdown and discharged from the lowest points of the equipment and pipelines is collected together, and then sent to the LPG tank farm by the propane pump (1218-P-107). The residual liquid hydrocarbons in the shutdown extraction main line are depressurized via an interconnect line to be converted into a gas phase and sent to the flare main line. During shutdown, the purging of the catalytic top circulation pipelines is handled in a unified manner by the catalytic unit; the small amount of oily wastewater remaining at the lowest points of the pipelines after purging is discharged into the oily wastewater main pipe of the gas separation unit. All pumps (centrifugal pumps) in this unit are equipped with minimum flow lines set according to the stable flow requirements of the pump manufacturer. The substandard materials produced by this device are collected and then transported, either under their own pressure or by pump, to the LPG tank area for storage. This device produces no direct exhaust gases, nor any waste residues. Circulating water is used for the cooling of the pump. The oily wastewater discharged from the container water separation packs, as well as that generated during maintenance, is collected in the underground main oily wastewater pipeline and then flows out of the device to the combined treatment facility or the plant’s overall oily wastewater treatment system. Chapter 2: Preparations for Commissioning with Feedstock 2.1 Conditions Required for Commissioning Commissioning must be carried out to high standards and with strict requirements, in accordance with the approved commissioning plan and procedures. It is essential to follow all prescribed procedures without omission, to maintain all required standards without compromise, and to make use of every minute available. Before feeding in the feedstock, it is necessary to thoroughly check and confirm that all conditions for trial operation are met. Production technicians should participate in the preparation of technical documents to obtain first-hand information. The conditions required for commissioning are as follows: 2.1.1 Completion of intermediate project handover. ⑴ The intermediate project handover can be carried out on a unit or system basis depending on the project progress, and it is necessary to strictly adhere to the \"Interim Provisions on Commissioning Work for Large and Medium-Sized Petrochemical Construction Projects\" in order to achieve a high standard of handover. ⑵There is complete verification documentation for the project quality compliance rate. ⑶“The issues related to the “three inspections and four determinations” have been resolved, and all remaining items have been properly addressed. ⑷The design change projects that affected the material feeding have been completed. ⑸The intermediate handover procedures for the project have been completed; all components such as the installation units, the main structure, auxiliary systems, waste treatment facilities, safety equipment, fire escape routes, and communication systems have been installed, and all have passed the acceptance checks in accordance with relevant standards. ⑹The handover of specialized tools for equipment installation, as well as the spare parts, materials, and technical documentation, has been completed. ⑺All temporary facilities used for on-site construction have been removed. ⑻The equipment and pipelines are well insulated. The device tag numbers, pipeline medium names, and flow direction indicators are all available. The area is clean, with no clutter. All types of lighting are in use, and the roads are clear. 2.1.2 The joint commissioning is complete. ⑴ Purging, cleaning, airtightness testing, pressure testing, water testing, and instrument calibration have all been carried out and verified. The purging and airtightness testing of the instrumentation system should be carried out in coordination with the process system. ⑵The equipment is in good condition and ready for use; individual and combined tests have been completed, any issues identified were resolved, and further testing was successful. ⑶The interlock calibration is complete, accurate, and reliable. The online analytical instruments, equipment, and DCS systems have been calibrated and are ready for use. ⑷The tools and equipment for the position are all available. 2.1.3 Personnel training has been completed. (1) Personnel for various job roles have received specialized training in areas such as processes, equipment, electricity, instrumentation, and safety, and have passed the relevant examinations. ⑵Personnel in various job categories must obtain work permits and pressure vessel operation certificates, while operators of CO waste heat boilers need to have special job permits. ⑶Workers in various positions receive safety training at the plant level, workshop level, and team level. Pass the examination and obtain a safety operation certificate. ⑷The domestic training for similar equipment has been completed. ⑸Job training, simulated training, and accident drills have been carried out to achieve the “three understandings and six skills”. (Three understandings: understanding the principles, understanding the structure, and understanding the plans and regulations) ； Six skills: knowing how to read diagrams, knowing how to operate, knowing how to maintain, knowing how to calculate, knowing how to communicate, and knowing how to troubleshoot faults). Improve the “six capabilities” (thinking ability, operational skills, coordination and organization ability, accident prevention ability, self-protection and first-aid ability, self-restraint ability). ⑹The operator enters the device in advance to become familiar with its operation process. 2.1.4 All production management systems have been implemented. (1) The workshop has a sound organizational structure, clear job assignments, and production operation systems for each team have been established. ⑵Establish a streamlined commissioning team composed of senior managers, functional departments, and workshops, adopting a model where each unit and each process is assigned to a specific person responsible, with management and functional departments playing a supervisory role, to ensure that responsibilities are clearly assigned to individuals. ⑶The company’s production scheduling has switched to shift work. ⑷The workshop has comprehensive management systems in place; ten systems have been established, including those regarding job responsibilities, routine inspections, shift handovers, safe production, quality control, financial accounting, technical training, and equipment maintenance. All types of management ledgers, record sheets, and registers are ready. 2.1.5 The start-up and commissioning plan has been explained to the production staff. (1) The operation procedures and the commissioning plan were explained, and through systematic training, discussion, etc., the operators and supervisors have become fully familiar with the contents of the plan. ⑵Each person has a copy of the basic information on the combined unit, temporary operation procedures, commissioning plan, and safety technical regulations. ⑶A testing plan must be in place for each stage of the testing, and it should be understood by everyone from commanders to operators. ⑷Based on the principle of \"not letting go of any incident\" since the commissioning of similar devices, analyses and summaries have been conducted to draw lessons from these incidents. 2.1.6 All utility systems are operational and functioning properly, and they can meet the requirements for the process testing of the combined plant. The pressure, flow rate, water quality, and dew point of systems such as medium and low pressure steam, process air, instrument air, circulating water, demineralized water, fuel gas, and domestic water all meet the process specifications; these systems operate stably and reliably. The drainage and waste discharge systems are also in use, and there are no leaks or losses in any of the systems, with good insulation. ⑵The power supply system is operating steadily, the power supply for instruments is stable, and the emergency power supply is in place; electricians and instrument technicians have begun to carry out shift-based inspections of the circuits. 2.1.7 All raw materials, auxiliary materials, spare parts, tools, and equipment have been fully prepared and placed in place. (1) The chemical raw materials and auxiliary materials, lubricants, as well as reagents and chemicals have been prepared as required, passed quality checks, and delivered to the designated locations. ⑵The catalysts must arrive on time in accordance with the schedule required for installation during testing. ⑶The three-stage filtration system for lubricating oil has been implemented, and the lubricating oil has been properly added to the lubrication points of various driving equipment as required. ⑷All storage tanks have been purged; the anti-static and lightning protection facilities for these tanks are in good condition, and the system is now in a ready state for use. The materials required for commencement have been stored in proper quality and quantity, and are ready for use at any time. ⑸Spare parts, accessories, and tools are available in sufficient quantity to meet the requirements for testing. 2.1.8 Preparation work for chemical analysis is complete. ⑴ A normal analysis and testing system has been established. ⑵The testing items, frequency, and methods have been determined; the instruments have been calibrated, the reagents are available, and the analysts are on duty. ⑶The sampling points have been determined, the sampling equipment has been prepared, and the responsibilities for sampling have been assigned. ⑷Analog sampling and analog analysis have been performed. The control indicators and quality indicators have been implemented. 2.1.9 The safety, fire protection, and first-aid systems are well-established. (1) There are complete systems, regulations, and records for safe production; a safety management system has been put in place, and personnel work after receiving safety training and obtaining the necessary certifications. ⑵The fire operation regulations, smoking ban regulations, and vehicle management regulations have been established and published. ⑶A fire inspection system and on-site management procedures for fire trucks have been established; fire fighting plans have been put into effect; fire roads are clear, and fire drills have been conducted. ⑷Fire-fighting equipment and safety gear are available at the posts, and everyone knows how to use them. ⑸Gas protection and emergency rescue measures have been implemented. ⑹The monitoring instruments are fully equipped, have been tested and calibrated, and have been installed in the designated locations. The on-site personnel are wearing appropriate personal protective equipment, and basic first-aid knowledge has been disseminated among the workers. ⑺The fire protection measures for the production facilities and tank areas, as well as the smoke and fire detectors and combustible gas and toxic gas monitors, have been put into use. The integrity rate reaches 100%. ⑻The safety valve has been pressure-tested, calibrated, set to the required pressure, and sealed with lead. ⑼Pressure vessels are certified after approval by the labor department. ⑽The blind flanges are under the management of a designated person, who ensures that all blind flanges have been added or removed as required, and prepares a diagram of the blind flanges. There is a record ledger, with a designated person signing to confirm the placement of signs on site. ⑾An on-site first aid station has been set up, equipped with ambulances and other facilities. Emergency responders are on duty 24 hours a day. ⑿The torches and various safety facilities are well-equipped, and the facilities for treating the ‘three wastes’ are either ready for use or already in operation. ⒀The instruments and chemical reagents required for environmental monitoring are all available, and the analysis procedures and reports have been prepared. Various environmental protection management systems, as well as the environmental protection control parameters, sampling points, and analysis frequencies for various facilities, have been approved and put into effect. ⒁The fire safety inspection must be completed. 2.1.10 The production scheduling system is operating normally. ⑴ The company’s production schedulers have been assigned and have passed the necessary assessments to take up their positions. ⑵A normal order has been established for test run scheduling, and a regular scheduling meeting system has been put in place. ⑶The dispatchers are familiar with various material transportation plans; the relationships regarding the mutual supply of materials between factories and between different units are clear, and the pipelines are already in use. ⑷During the trial operation period, raw materials, fuel, products, by-products, and power balance were all brought under the normal management of the scheduling system. ⑸The communication system operates reliably; the command system phones are functional, and the direct dispatch and fire alarm lines work properly. Wireless phones and telephones provide clear calls. 2.1.11 The process preparation for the combined unit and the confirmation of commissioning conditions have been completed. The production and engineering departments shall ensure proper on-site coordination, as well as the confirmation of pre-commissioning and operational conditions. Before the trial operation, it is necessary to conduct a thorough check item by item and clause by clause in accordance with the \"Interim Provisions on Trial Operation of Large and Medium-Sized Petrochemical Construction Projects\" and the requirements regarding the conditions that must be met for feeding materials as specified in the \"Overall Trial Operation Plan\". It is essential to organize the tasks by system and unit; the design confirmation forms must be signed by all relevant parties and filed away to ensure accountability is established. It is essential to verify conditions such as the process flow, equipment pressure testing, internal component installation, concealed works, low-temperature materials, purging, testing, and airtightness. ⑴The utility facilities are well-developed, ensuring that water, electricity, steam, air, etc., meet the requirements for equipment commissioning. ⑵The instrument control valves of the unit, as well as the interlocks, alarms, on-line chromatograph, DCS, ESD system, etc., have all been calibrated and are in good condition. ⑶The electrical system has been calibrated to ensure proper power supply and power availability in emergency situations. ⑷The product refining unit, MTBE unit, polypropylene unit, and other facilities are all in a state ready to receive materials and start operation. 2.1.12 The logistics support measures have been implemented. ⑴ A logistics team with strong capabilities in terms of ideology, skills, and work ethic, along with complete equipment and tools for logistics support, has been established. ⑵The scope and responsibilities for shipping have been defined. ⑶The shipping staff are on duty and wearing identification badges. ⑷The shipping duty location has been identified and marked, with 24-hour duty in place. ⑸Material supply services are provided on-site with 24/7 duty coverage. ⑹Mechanical, electrical, instrumentation, and maintenance personnel are on duty. 2.1.13 On-site security has been arranged ⑴ The organization, personnel, and transportation for on-site security have been secured. ⑵Systems for factory access and security measures for key areas such as control rooms have been established. ⑶Measures for on-site security have been implemented and a notice has been issued. 2.2 Comprehensive Quality Inspection 2.2.1 Tower Inspection ① Check layer by layer to ensure that all trays and components inside the tower are properly installed and that any debris has been removed. Check the size of the overflow opening, the height of the weir, and the levelness of the trays to ensure they meet the design requirements. Verify that the floating valve is clean and free of defects, moves freely, and that the sieve plates have no clogged pores. All tray fasteners are properly installed, ensuring effective tightening. All distributors are properly installed and positioned, with unobstructed distribution holes. ②Check whether each manhole, flange, screw, and gasket meets the installation requirements. ③Check that all attachments (safety valves, pressure gauges, level gauges, vent valves, etc.) are present and in good working condition. ④Check whether the ladders on each platform are secure. ⑤Are the material specifications of the inlet and outlet flanges of various towers, vessels, and heat exchangers, as well as those of the manhole flange gaskets and bolts, in compliance with the requirements? 2.2.2 Cooling and exchange equipment: ① Check whether the thermometers and pressure gauges associated with it are complete and in good working condition, and ensure that the drain and pressure testing plugs have been reinstalled and tightened properly. ②Are the process connections and accessory installations up to standard? ③Check whether the painting and insulation quality meet the requirements. 2.2.3 Pumps ① Check whether the pump accessories (pressure gauge, coupling guard, ammeter, etc.) are complete and in good working condition, and whether the foundation screws are tight. ②Check whether the coupling installation and shaft seal leakage meet the requirements. ③Check that the cooling and oil sealing systems are unobstructed; add lubricant to the level specified by the oil gauge. ④Whether the turning gear operates smoothly, whether the motor rotates in the correct direction, whether the motor is properly grounded, and whether the pump is in good condition. ⑤Whether the process connections and accessories are installed as required, and whether the installation of the associated valves facilitates operation and maintenance. ⑥The lubricating oil or grease for the air-cooling fan is applied as specified, and the air-cooling fan blades move smoothly. ⑦Are the inlet and outlet valves, flanges, bolts, and gaskets of the pump up to standard? Is the packing properly compressed, and are the valves functional and easy to operate? ⑧Whether the pump cooling water system is installed correctly. 2.2.4 Process pipelines ① Check whether the installation of pipelines, fittings, and valves meets the process requirements, whether they are easy to operate and maintain, and whether insulation and heating systems are in good condition. ②Check whether the installation of each check valve, ball valve, steam trap, etc. is correct. ③Are all the thermocouples, thermometers, pressure gauges, etc. in the pipeline sections complete and in good condition, and are they easy to inspect and maintain? ④Check whether the fixed and movable supports are secure and suitable, whether the pipe rack foundation is tilted or sunken, whether the supports are firm, and whether the slope is appropriate. ⑤Whether the pipelines related to communication with external devices have been installed. Whether the blind plates are installed accurately and completely. ⑥Based on the construction drawings, a thorough, careful, and comprehensive inspection is carried out in accordance with the manufacturing process to ensure that the installation of equipment and pipelines is correct and meets the requirements, as well as that the valve positions are convenient for operation. ⑦In accordance with the construction specifications, inspect all equipment such as towers, vessels, heat exchangers, and pumps to ensure that there are no defects or errors in their construction quality. ⑧Check whether the valves, packings, and gaskets are properly installed, whether the flanges and gaskets are in place as required and correctly fitted, whether the bolts are fully tightened, and whether the materials meet the design specifications. ⑨Whether the pipeline specifications, models, and materials meet the design requirements. ⑩Is the installation direction of the check valve and orifice flow meter correct? Check whether there is false welding or missed welding in the welds of thermometers and thermocouples. 2.2.5 Safety Facilities ① All fire-fighting and extinguishing equipment is properly in place. ②The fire water system is operating properly, and all fire hydrants or fire monitors are in good condition. ③All safety valves are in service. ④Various safety equipment: air respirators, gas masks, first-aid equipment, etc., are in good condition and ready for use. ⑤All miscellaneous items at the installation site, except for the equipment required for startup and operation, have been cleared away. ⑥Set up the necessary warning signs and obstacles. ⑦Whether a safety valve file exists, whether the set value is accurate, and whether there are seal marks. 2.2.6 Instruments ① All control valves have been tuned to operate smoothly throughout their range of motion, with the correct direction of operation. ②The thermocouple has been calibrated, and its measurement deviation is within the specified range. The flow, pressure, and level measurement units are functioning normally. ③All on-site primary instruments are in normal operation and display correctly. ④ The DCS control system is operating normally. ⑤Check whether the instrument control circuits of the device meet the design requirements. Check whether the installation locations of the device’s thermometer, level gauge, pressure gauge, and pressure sampling points meet the requirements and are conducive to use and maintenance. 2.2.7 Utility Systems ① Fresh water, circulating water, and steam intake systems; steam pipelines are equipped to drain condensate, and the traps on these pipelines are operating properly. ②Unpurified air, purified air, and nitrogen introduction units. ③All pumps and fans are already energized. 2.2.8 Blind Flanges: Blind flanges are used to isolate pipelines and equipment from one another. After the installation work or repairs are completed, and inspections of all systems and equipment have been finished, a list of blind flanges can be prepared in accordance with the established procedures. The blind flanges are then installed or removed step by step, with each step being verified individually. Chapter 3: Options for Introducing Steam, Circulating Water, Nitrogen, and Purified Air 3.1 Purpose: To purge, flush, connect, and pressure-test the power system to ensure its proper operation, thereby preparing the process system for purging, connection, and pressure testing. Acceptance is carried out in accordance with the three-inspections and four-fixations standards, and the intermediate handover has been completed. A comprehensive inspection of the equipment has been carried out, and all identified issues have been resolved. The gas fractionation unit, the liquefied gas tank farm, and the power system all have access to power media such as water, steam, air, and nitrogen. Utility media generally refer to water, electricity, air, steam, and nitrogen. Moisture includes industrial water, circulating water, deionized water, and deoxygenated water. Winds are generally divided into purified winds and unpurified winds. Industrial electricity is generally 380 volts, while large-scale units usually use 6000 volts. It is generally divided into low-pressure steam, medium-pressure steam, high-pressure steam, and ultra-high-pressure steam. Nitrogen is classified into low-pressure nitrogen, medium-pressure nitrogen, and high-pressure nitrogen according to pressure levels. The utility media used in this device include: circulating water, unpurified air, instrument air, low-pressure nitrogen, high-pressure nitrogen, low-pressure steam, and low-temperature hot water. 3.2 Introducing 1.0 MPa steam 3.2.1 Requirements for introducing 1.0 MPa steam: When the unit is started up for the first time or during shutdown for maintenance, the steam system is not in use, and there is a considerable amount of steam condensate in the steam pipelines. Therefore, first, the drain valve of the 1.0 MPa steam pipeline network in the plant area must be opened to remove the steam condensate from within that pipeline, thereby preventing water hammer when steam is introduced. When opening the drain valve, be careful not to open it too wide or too quickly to avoid being scalded by steam. After steam is observed at the drain point, the drain valve remains slightly open. When the unit is started, the valves in the boundary zone are closed, and at this time the steam in the unit’s steam pipelines gradually condenses into water. Therefore, it is necessary to open the valve on the device’s trap bypass line in order to drain the condensate from the steam pipeline, thereby preventing water hammer when steam is introduced. After draining the condensate from the steam pipeline, the bypass valve of the trap should be kept slightly open. After the condensate in the steam pipelines inside and outside the device has been drained, steam can be introduced into the device. Steam introduction principle: Introduce the main pipeline first, then the branch pipelines. Slightly open the main valve of the steam pipeline in the unit area to warm up the steam pipelines inside the unit. When warming up the steam pipeline, be careful to open the main steam valve slowly and not to increase its opening degree too much. The heating rate of the steam pipeline should be kept at ≤30°C/h to prevent water hammer in the pipeline, as well as excessive thermal stress that could damage it. On-site, whether there are abnormal noises from the pipelines is used as a reference for operating the valves. If abnormal noises are heard in the steam pipeline, the valve should be closed, and its opening degree should be reduced slightly until the abnormal noises cease. When the pressure indicated by the steam pressure gauge in the boundary zone reaches the process operating pressure, fully open the 1.0 MPa steam valve in the boundary zone. The steam condensate generated during the heating of the steam pipelines is promptly drained through the slightly open bypass valve of the steam trap. Once the drain point shows steam, open the valve upstream of the trap and close its bypass valve. Be careful not to open the valve on the drain separator bypass too wide; keep people away from the discharge area to prevent burns. Open the valves located upstream of the steam control valves in each steam heat exchanger; slightly open the backflow valves of these control valves to drain the steam condensate from the steam feed lines of the heat exchangers, while directing the steam to be used in front of the control valves. Make sure the valve downstream of the steam control valve in the steam heat exchanger is closed, to prevent the heat exchanger from being in a dry steam condition, which could cause leaks. Also, the opening degree of the backflow valve of the steam control valve should not be too large, to prevent burns from steam. Once the drain point shows steam, close the backflow valve. After purging, pressure testing is carried out using the pipeline at maximum steam pressure, and leaks are checked thoroughly along the entire process flow. 3.2.2 Intake of 1.0 MPa steam process 3.3 Intake of circulating water 3.3.1 Requirements for circulating water to be introduced into the unit Before introducing circulating water into the unit, it is necessary to modify the circulating water flow path within the unit first. For cooling equipment equipped with a circulating water control valve, open the valves upstream and downstream of the circulating water supply (return) control valve, manually open the circulating water control valve slightly (a valve opening of 10% is appropriate), close the bypass valve of the circulating water control valve, and open the circulating water supply (return) valve. For cooling equipment without a circulating water control valve, simply open its inlet and outlet valves. After the circulation water flow within the unit is rerouted, the main valve for feeding circulation water into the unit can be opened to introduce the circulation water into it. The most crucial aspect in introducing circulating water to the system is ensuring that the highest points of each heat exchange device are vented, in order to prevent air buildup within these devices, which could reduce their heat exchange efficiency and affect their performance. Therefore, the exhaust valve for each shell side or head of the heat exchanger equipment must be opened to allow exhaust, and it should be closed once water is detected. At the same time, the high-point vent valves on the return piping of each heat exchanger unit should also be opened for venting; these valves should be closed once water is detected. Additionally, the cold exchange equipment should exhaust in ascending order. After all the cooling equipment in the unit has completed its exhaust process, open the main valve for the circulating water entering the unit to initiate the circulation of water within it. Since the circulating water is exhausted from the highest point of the heat exchange equipment, it is necessary to wear a safety belt when exhausting air from such equipment to prevent falls and injuries; if needed, scaffolding can be used for working at heights. First, disassemble and assemble the relevant parts as required, then introduce water. Following the sequence of the process, each disassembly point is rinsed sequentially to remove impurities such as stolen goods and rust, after which it is reinstalled in place. After thorough flushing, the pipeline is tested for leaks at maximum water pressure (below the cooler’s design pressure). 3.3.2 Circulating water introduction process 3.4 Nitrogen introduction 3.4.1 Requirements for nitrogen introduction Introducing nitrogen is a relatively simple operation. First, open the main nitrogen valve in the plant area to introduce nitrogen into the nitrogen piping network inside the plant. After nitrogen supply is stopped for a period of time, impurities such as liquid accumulation and rust may form inside the nitrogen pipelines. Therefore, secondly, the backflow valve at the end of the nitrogen main pipe inside the device must be opened to purge the nitrogen main pipe with the device’s own medium. After the nitrogen main pipe has been purged, close the backflow valve at the end of the nitrogen main pipe. If working at height, be sure to wear a safety belt. When purging the main nitrogen pipeline, one should stand in the upwind direction to prevent suffocation caused by nitrogen. Finally, open the backflow valves of the nitrogen pipelines for each device one by one to purge the nitrogen pipelines of those devices; once purging is complete, close the backflow valves. The nitrogen pipelines at various utility stations within the facility also need to be purged. 3.4.2 Nitrogen introduction process 3.5 Introduction of instrument air – Introducing instrument air is a relatively simple operation. First, open the main instrument air valve in the device area. After the instrument air is shut off for a period of time, impurities such as liquid accumulation and rust may form within the instrument air pipelines. Therefore, secondly, the backflow valve at the end of the instrument air main pipe of the unit must be opened to purge the instrument air main pipe with its own medium. After the main instrument air pipeline has been purged, close the backflow valve at the end of the main instrument air pipeline. If working at height, be sure to wear a safety belt. Finally, contact the instrument technician to purge each instrument air branch line. 3.6 Introducing unpurified air – Introducing unpurified air is a relatively simple operation. First, open the main valve for unpurified air in the device area. After the non-purified air supply is shut down for a period of time, impurities such as liquid accumulation and rust may form within the non-purified air pipelines. Therefore, secondly, the backflow valve at the end of the unpurified air main of the unit must be opened to purge the unpurified air main with its own medium. After the main non-purified air pipeline has been purged, close the backflow valve at the end of the main non-purified air pipeline. If working at height, be sure to wear a safety belt. Finally, open the valves of the unpurified air pipelines in each utility station within the unit one by one, and purge the unpurified air pipelines in those utility stations using their own medium. After the unpurified air pipeline has been purged, close its valve. Chapter 4 Steam Purging Plan 4.1 Purpose of Purging Purging is generally applied when a plant is put into operation for the first time, after it has been idle for an extended period, or following major renovations that involve the addition or replacement of equipment. Operation resumes after normal maintenance, and since purging has been carried out during the shutdown period, it is generally not necessary to perform a full-system purge; only the equipment and pipelines that have undergone welding modifications require such purging. The power system is purged, flushed, pressurized, and tested to ensure its proper operation, thereby preparing the process system for purging, pressurization, and testing. Purpose of purging: (1) Remove rust, slag, and other debris from equipment and pipelines, to prevent valves from getting stuck and to avoid blockages in orifices, pipelines, as well as in equipment and pumps ； ⑵Check pipelines, equipment, valves, flanges, and welds for leaks to ensure smooth operation of the pipelines and equipment. ⑶Inspect the changes in process pipelines and equipment under thermal conditions. ⑷To help operators become more familiar with and proficient in the process. 4.2 Conditions required for purging: ① Acceptance shall be carried out in accordance with the three-inspections and four-fixing standards, and intermediate handovers shall be completed. ②A comprehensive inspection of the equipment has been carried out, and all identified issues have been resolved. ③The gas fractionation unit, as well as the tank farm and related systems, are equipped with all the necessary medium streams such as steam, purified air, unpurified air, nitrogen, circulating water, heated circulating water, and top-loop reflux from the catalytic unit. ④A comprehensive inspection revealed no issues, and all problems identified have been resolved; the site is now ready for construction to begin. 4.3 Conduct acceptance or re-inspection of the entire installation in accordance with relevant standards. ① Verify all drawings, construction acceptance documents, and other related records to ensure they are complete and accurate before archiving them. ②For all equipment without sealed manholes, a dedicated person must enter to conduct inspections, which include checking whether the connections and welds of the internal components meet the requirements of the installation design. All testing nozzles and openings are unobstructed. All internal foreign objects such as slag, electrodes, bolts, nuts, etc. must be thoroughly cleaned away. After the inspection is complete, and once all identified issues have been fully resolved, the person in charge of the workshop will decide whether to seal the manhole. ③For the manholes of sealed equipment, inspect from the outside to ensure that the bolts, nuts, gaskets, and tightening degree meet the requirements. At the same time, check whether the connections of related equipment and pipelines meet the requirements correctly. ④Any issues such as unconnected components, missing valves, absent bolts and gaskets, as well as any undiscovered cracks, defects, or insulation problems in the process pipelines, water, electricity, steam, air, etc., must be identified and addressed. ⑤Check whether the pump is properly installed as required, whether the cable connections, cooling water pipelines and inlet/outlet pipeline valves are in order, and whether the pressure gauges are functional, so that the pump is ready for operation. ⑥Contact the company’s dispatch team to verify whether there are any unfinished tasks related to the pipelines, valves, and equipment outside the unit, and address them as soon as possible. Contact the instrumentation and electrical engineering teams to confirm whether there are any unresolved issues in those fields. ⑦Are the fire-fighting equipment and supplies complete? The equipment is thoroughly cleaned to ensure that work is completed, materials are removed, and the area is clean. ⑧Are various types of lubricants, greases, and some filtering equipment ready? ⑨Are tools such as valves, wrenches, pipe clamps, and tape ready? ⑩Remove or install the relevant blind flanges as needed. 4.4 Preparation for purging 4.4.1 Ensure that temporary blind plates are readily available, and that steam or compressed air, as well as the air and steam supply sources and their connection pipelines, are properly prepared. 4.4.2 Remove the control valves on the pipeline and the orifice flow meter, replace them with corresponding splices, and cover the inlet flanges of all moving and stationary equipment with metal sheets. 4.4.3 The pipeline purging plan is complete and feasible, and the purging table has been prepared. 4.4.4 The pipelines have been tested for leaks using water or air pressure, and the water has been largely removed; the pipelines are now ready to be reinstalled. 4.4.5 Safety equipment as well as all necessary items for purging must be prepared. 4.4.6 Relevant departments shall assist in carrying out the pipeline purging process, ensuring that no pipeline, valve, or weld is overlooked. Any issues detected during purging must be recorded by a designated person, and they should be addressed after the steam supply is stopped or the pressure is reduced. 4.4.7 All steam gaskets must be replaced with graphite wound gaskets; however, when reinstalling them after purging the pre-disconnection area, they should be connected in accordance with the standard piping requirements. 4.4.8 All steam pipelines have been constructed in accordance with the design. The supports, hangers, etc. have passed inspection and meet the design requirements, and the fixing bolts of the compensators have been removed. Mark the relative positions of the supports and pipe racks at key areas of the pipelines. 4.4.9 Install temporary piping for purging at the end of the steam main, along with gate valves and temporary steam exhaust pipes. The pipe outlet should be at an angle of 30°–40° upward, and the exhaust pipeline must have solid support to withstand the reaction force from the exhaust gas. The exhaust pipe should be led outdoors and clearly marked. 4.4.10 An isolation zone shall be established within 50 meters in front of the exhaust pipe, with clear markings, to prevent steam or ejected materials from causing injury. It is under the responsibility of a designated person, and access by pedestrians and vehicles is strictly prohibited. 4.5 Purging Principles 4.5.1 Steam pipelines, condensate lines, and heat tracing lines are purged with steam; since non-thermal pipelines cannot be purged with steam, the rest are purged with compressed air. 4.5.2 For steam purging, preheat the pipelines first; it is essential to drain condensate before introducing steam. The introduction of steam should be done slowly, following the principle of starting with a small amount of steam before increasing it. Prevent water hammer from occurring; in the event of water hammer, it is necessary to reduce or stop the steam supply and drain the condensate. When supplying steam for the first time, supervision must be provided at the drainage point to avoid burns from the steam. Steam pipes should be purged with high-flow steam, at a flow rate of not less than 30 m/s. During purging, notify all relevant personnel on site; each outlet is assigned to a responsible person who must pay attention to safety and remain in constant contact with those operating the inlet valves. 4.5.3 The purging of pipelines shall be carried out in an orderly manner, from high to low and from large to small. Air purging is performed intermittently using the utility compressor; the purging pressure shall not exceed the design pressure of the containers and pipelines, and the flow rate shall be no less than 20 m/s. 4.5.4 The inlets and outlets of each rotating equipment shall be isolated, while stationary equipment shall decide whether to participate in the purging depending on the circumstances or its structure. 4.5.5 During the purging process, the valves on the pipelines must be opened and closed frequently in order to blow out debris from the dead corners. If you find that the valve is stuck, do not try to open or close it forcefully to avoid damaging the valve. 4.5.6 Each pipeline to be purged should be marked on the PID diagram, and the process should be recorded in the purge table for verification, in order to prevent leaks. During the air purge process, once it is visually confirmed that no smoke or dust is coming from the exhaust outlet, a wooden target covered with white cloth or painted white should be placed at that outlet for inspection; it is considered satisfactory if no rust, dust, moisture, or other debris are present on the target within 5 minutes. 4.5.7 After each pipeline has been purged, a dedicated person is required to conduct inspection; the purge pressure and duration are determined based on the results of the purification process, and the pipeline is reinstalled properly so as to meet the requirements for water transportation. 4.6 Specific requirements and precautions for purging 4.6.1 When cleaning the pipelines, it is not allowed to allow debris inside them to enter towers, containers, pumps, and heat exchange equipment; methods such as removing flanges and valves, and inserting thin iron plates at the removed flanges as a barrier, should be used. 4.6.2 Before purging, remove the control valve, flow-limiting orifice plate, filter, mixer, meter, etc. first. Remove the thermometer with a range below 200°C, install a plug, and close the connection valve between the instrument’s primary gauge and the pipeline. 4.6.3 During purging, it should be carried out in stages; once the previous section of the pipeline has been cleaned, the flanges should be connected to proceed with purging the subsequent section. 4.6.4 All pipelines shall be classified as primary or secondary according to the process flow, and each system, section, and pipeline shall be thoroughly cleaned; no dead ends or blind spots shall remain that could affect operations. 4.6.5 When the sweep gas passes through the control valve, it takes the bypass line and is vented at both ends. When purging the cold exchange equipment, one section must be purged while the other is vented to prevent damage to the equipment. 4.6.6 Dehydrate and drain condensate before steam is introduced; the steam supply should be gradual, and condensate should be drained along the pipeline to prevent water hammer. 4.6.7 During purging, all sampling points, instrument leads, pressure gauge tubes, level gauges, etc. should be purged simultaneously to ensure unobstructed flow and prevent blockages. 4.6.8 The temporary steam vent hose must be tied securely to prevent it from moving around and causing injury in case of a sudden increase in steam volume. 4.6.9 When blowing steam into the tower, care must be taken to do so gradually to prevent the trays from being overturned; meanwhile, the top of the tower should be vented and the bottom should have condensate drained off. 4.6.10 Before starting the cleaning process, the inlet and outlet valves of the pump should be closed, and a temporary filter should be installed at the pump’s inlet to prevent debris from entering the pump. 4.6.11 Purge the raw material and product pipelines to the tank farm or the boundary area of downstream units, then remove the flanges to drain the contents. 4.6.12 Install the relevant blind flanges before purging and keep records. Operators must be familiar with the process and know the steam injection points and steam discharge points. After the pipeline purging is completed successfully, the pipeline purging record should be filled out carefully. 4.6.13 The steam pressure during purging should not be too low, otherwise it will affect the effectiveness of the purging. 4.6.14 The purging process is divided into three stages: pipe warming, pressure increase and decrease in the pipeline network, and purging. First, purge the steam main; once the main has been thoroughly purged, then purge the branch pipes. A. Heating the pipe: ⑴ Open all drain valves to drain any water accumulated in the pipe, thereby preventing water hammer. ⑵Open the vent valve at the end of the steam main. ⑶A small amount of steam is introduced to preheat the steam pipeline and raise its temperature. Slowly open the valve on the main steam pipeline in the area in question, and gradually increase the temperature of the pipeline to allow it to expand smoothly. This prevents sudden increases in temperature from causing excessive local stress that could damage the pipeline. Maintain a heating rate of 10–15°C per hour until the pipeline temperature reaches 200°C. ⑷During the pipe warming process, pay special attention to checking the displacement of pipeline supports and the expansion and contraction of compensators. If any abnormality is detected, report it to the dispatcher promptly to initiate steam shutdown procedures. B. Pressure raising and lowering of the pipeline network: (1) Close the vent valve at the end of the main steam pipe, and slowly open the valve on the main steam pipe outside the plant to increase the steam pressure in the pipes. ⑵When the pressure in the steam main reaches 0.1 MPa, it is increased by 0.1 MPa each time, with one grade increase for every 0.1 MPa; the quality of the pipes in the areas monitored by the personnel along the line is checked, and any leaks are reported to the dispatch team. Once the pressure level is reached and it is confirmed that there are no issues with the pipes, open the vent valve at the end of the steam main to release the pressure. After checking and confirming no issues after 15 minutes, close the vent valve at the end of the steam main, then continue to increase the pressure to the next level; once it meets the requirements, release the pressure, and repeat this process until the pressure reaches 0.8 MPa. C. Purging: (1) If the pressure in the pipeline network is sufficient to enable continuous purging of the steam pipes, open the main steam valve to carry out continuous purging of the pipes. ⑵If the pressure in the pipeline network is not sufficient for continuous purging of the steam pipes, it is necessary to first close the end valves and increase the pressure in the pipes. Once the pressure reaches 0.8 MPa, the end valves are opened to carry out the purging process. When the pressure drops to 0.4 MPa, the end control valves are closed again to raise the pressure further. This process of purging is repeated, with the flow rate having to be at least 30 m/s. The number of purging cycles is determined based on the site conditions. ⑶After purging for a certain period of time, close the end valve, place the testing board, and open the valve to conduct the test. Purge for 15 minutes each time, then close the end control valve and inspect the board until there is no rust, slag, or other contaminants on it. 4.6.15 Throughout the entire purging process, unified arrangements are made by the company’s dispatch team; operation points are established at the main steam valve inside the unit, the main steam valve outside the unit, and at the end of the steam main. The pressure testing is organized and inspected by the project owner, while the construction unit installs the pressure testing equipment and provides assistance, forming a purging team. 4.7 Purging medium: 1.0 MPa superheated steam, at a temperature of 250–300°C. 4.8 Qualification criteria: Polished wooden boards or aluminum alloy plates are usually placed at the exhaust outlet for inspection; a clean board free of rust or debris indicates that the purging is successful. 4.9 Purging procedure: Specifically based on the actual process of the gas fractionation unit. The steam feed points are generally at the bottom of towers and containers, as well as at the pump outlets; the drainage points are usually at the tops of towers and containers for venting, as well as at the flanges removed in the plant boundary area, and at the lowest points of towers, containers, heat exchangers, and control valve assemblies for condensate drainage. The specific flowcharts are as follows: 4.9.1 Purging process for raw materials and liquefied gas storage tanks; 4.9.2 Process flow of the depropanization tower system; 2.9.3 Deethanization tower system; 2.9.4 Propylene Tower-1 system. Chapter 5: Water flushing plan. Individual unit testing, water flushing, and water operation are generally applicable when the plant is started up for the first time, after it has been idle for a long period, or after major renovations. In cases of normal maintenance followed by restart, the equipment has already withstood prolonged operation, and purging has been carried out after shutdown; the equipment is also cleaned during maintenance, so there are no large amounts of debris in the system. Therefore, normal startup usually does not require individual unit testing, water flushing, or water operation. 5.1 Single-unit trial operation 5.1.1 Purpose of single-unit trial operation The single-unit trial operation is carried out simultaneously with the water connection test, in order to assess the performance of the pump as well as the quality of the construction work. 5.1.2 Preparations before testing: Preparatory work must be carried out before testing to ensure its smooth progress. ⑴Check the installation or maintenance records to confirm that the maintenance or installation data is correct. ⑵The motor passed the individual test, and its direction was confirmed to be correct. ⑶Before starting the pump, the bearing must rotate smoothly when turned by hand. ⑷The lubricating oil, cooling water and other systems are in good condition, and all accessories are complete and functional. ⑸There is no jamming or abnormal noise during shaft rotation, and the shaft seal leakage is within acceptable limits. ⑹Before testing the pump in operation, start it once to observe its rotation; if any abnormalities are detected, the power supply should be cut off immediately for handling. If the rotation is normal, continue operating. 5.1.3 Commissioning requirements ⑴ Centrifugal pumps must not be tested under no-load conditions; they should be tested while under load. ⑵The temperature of sliding bearings shall not exceed 65°C, and the temperature of rolling bearings shall not exceed 70°C. ⑶The vibration level of the pump must not exceed the specified standards, as shown in the table below: Rated speed n/min: 3000, 1500, 1000, 750 and below. Vibration level in mm: 0.06, 0.09, 0.13, 0.16. ⑷ The pump should operate smoothly without any abnormal noises; the cooling water and lubricating oil systems must function properly, and there should be no leaks in the pump or its associated pipelines. ⑸Control the flow rate, pressure, and current within specified ranges. 5.1.4 Acceptance The trial-operated pumps are accepted in accordance with the 10th edition of the \"Standards for Centrifugal Pumps in the Petroleum, Heavy Chemicals, and Natural Gas Industries\". ⑴After 24 hours of continuous operation, all technical specifications meet the design requirements, satisfying the production needs. ⑵It meets the good condition standard. ⑶The documents are complete and accurate, and the acceptance procedures shall be carried out in accordance with relevant regulations. 5.2 Water Flushing 5.2.1 Purpose of Water Flushing The purpose of water flushing is to thoroughly remove rust, slag, and other debris from towers, containers, heat exchange equipment, and pipelines, thereby preventing damage to pumps and blockages in control valves, flow meters, etc. This ensures unobstructed flow within the pipelines, preparing them for water testing. The main pumps are tested under load. 5.2.2 Conditions required for water flushing: (1) The purging of the equipment has been completed. Equipment, pipelines, and instruments meet production requirements. ⑵The device’s drainage system is unobstructed. Water, electricity, steam, purified air, and unpurified air are all introduced into the device. ⑶All the orifice plates, flow meters, control valves, instruments, etc. that needed to be removed have been taken out, and all the blind plates that needed to be installed have been added. ⑷All vents that are available should be fully opened; for systems without vents, signs should be placed at the flanges and valves to be removed in order to allow temporary drainage. ⑸All gauge lead valves are closed. The individual test run of the pump has been completed. ⑹The temporary pipelines for water flushing have been installed. 5.2.3 Principles of water flushing ⑴ Open the manual valves in front of the inlets of all containers, towers, pumps, and heat exchangers. When it cannot be disassembled, use the auxiliary line first; after cleaning it thoroughly, then use the main line. ⑵The flushing should be carried out intermittently and in stages; once the previous section of the pipeline has been cleaned, the flange is connected to proceed with flushing the subsequent section. ⑶All pipelines are sorted by process to determine primary and secondary ones; each system is flushed individually, and parallel devices have their flushing sequences exchanged. ⑷Level gauges, pressure gauge short tubes, sampling pipes, vent pipes, etc. should all be flushed clean simultaneously. 5.2.4 Precautions for water flushing: (1) Drain water regularly from the bottoms of various towers and containers, as well as from the low-point vents of control valves and at locations where flanges are removed, in order to remove debris. ⑵Once the pump is started, its operation must be monitored by a dedicated person. The discharge volume should be kept at 1/3 to 1/2 of the pump’s capacity; in other words, the pump’s outlet valve should not be opened fully. The current flow also needs to be controlled, and overloading is strictly prohibited. ⑶After the water flushing is complete, the removed orifice plates, flow meters, control valves, filters, and flanges must be reinstalled. The gaskets used for reinstallation must meet the specified requirements and be installed correctly. ⑷After the water flushing is complete, drain all the water remaining in the pipelines and equipment. When draining the system, the vent valves at the top of the tower and containers must be opened first to prevent negative pressure from damaging the equipment. 5.2.5 Water flushing procedure: First, use a pump to fill the tower and containers with fresh water; the drainage points are generally at the bottom of the tower and containers, as well as at the flanges of the first valves at the inlets of equipment such as pumps that feed water into the tower and containers. Drain at the lowest points of towers, vessels, heat exchangers, and control valve assemblies. The specific procedure is as follows: Fresh water is introduced from the high-pressure gas pipeline of the gas fractionation unit for water-cooling operation. 5.3 Water-cooling operation 5.3.1 Purpose of water-cooling operation: To primarily check whether the static equipment and pipelines are leaking, whether the rotating equipment is in good condition, whether the instruments and computers are accurate and sensitive, and whether the operators are familiar with the process and the performance of the equipment’s instruments. Specifically, it achieves the following purposes: (1) To examine the performance of pumps over an extended period of time. ⑵Calibrate instruments for flow, pressure, level, etc. ⑶Streamline the process. ⑷Conduct technical training and accident drills to help operators become more familiar with the processes and operating methods. 5.3.2 Preparatory work before water transportation: Preparation work must be carried out prior to water transportation to ensure the smooth progress of the trial run. ⑴The individual test run of the pump is complete, and the pipelines and equipment have been flushed and pressure-tested. ⑵According to the process flow, check whether the valves are opened and closed correctly, and whether pressure gauges and other devices are properly installed. ⑶Check that all orifice plates, flow meters, control valves, filters, and flanges are properly installed. ⑷Temporary filters have been installed at the inlets of each pump. ⑸Improve the water intermodal transport process. Install blind flanges on the inlet and outlet pipeline fittings, and assign a dedicated person to conduct inspections and keep records. 5.3.3 Precautions for water interconnection ⑴ For the towers and vessels involved in the water interconnection, the liquid level should be maintained at 50%–70%, to ensure proper water circulation without causing the pumps to run dry. ⑵The backup pumps should be used in rotation, and care should be taken to adjust the pump flow rate in order to maintain water balance. Attention should also be paid to the motor current, as overloading the motor can lead to its damage. Switch the backup pump every 2 hours. ⑶During water transportation, all control circuits must be in operation; control valves should be moved frequently, and any issues such as sticking or blockages must be addressed promptly. It is also necessary to keep accurate records of flow rate, pressure, and liquid level data. ⑷It is strictly prohibited to allow water to enter the air system pipelines, nitrogen lines, or steam lines. ⑸After the water transfer is completed, open the low-point vent valves of the process pipelines and equipment to drain water, making sure that the top vent valves are also opened. ⑹After the pumps have been evacuated, stop them and remove the inlet filters of the pumps. ⑺As required, the temperature of the motor bearings and the vibration levels of the machine body are tested and recorded. ⑻During the intermodal transport process, detailed inspections of equipment and piping facilities are carried out; it is considered satisfactory if there are no leaks and everything is in good working order. ⑼After the water transfer is complete, the system’s water is drained completely, and any remaining water is blown out using nitrogen or compressed air. ⑽In water intermodal transport, if a rapid drop in pressure is observed, it is necessary to check whether the process is correct or if there are leaks in the equipment and pipelines, and to address the issue promptly. ⑾After the water transfer is completed, check whether the sewer is unobstructed; open the low-point drains of the process pipelines and equipment to drain any remaining water, then close the valves and restore the blind flanges to their original position. ⑿After the water transfer operation is completed, open the large cover of the pump inlet filter, remove the temporary filter screen, and reinstall the original one. ⒀During the water transfer process, wastewater from each piece of equipment should be discharged separately into the underground oil waste tank system; this allows for checking whether the wastewater discharge pipelines are unobstructed. It is also possible to use this opportunity to test the operation of the underground oil waste tank system as well. 5.3.4 Water flushing process: Water flushing is carried out after the initial wash, at which point most of the debris in the system has been removed. Specifically, it depends on the actual process of the device. Go through each control circuit one by one in sequence. The low points of towers, vessels, heat exchangers, and control valve assemblies are drained regularly. The specific process is as follows: Chapter 6 Device Airtightness Plan 6.1 Purpose of Airtightness During the commissioning of a device, many sealing surfaces (points) of equipment and pipelines are involved, such as manholes on containers, end caps of heat exchange equipment, flanges on pipelines, and new welds on modified pipelines. After these moved sealing surfaces are reset, it is unknown whether their sealing performance meets the requirements; therefore, a gas-tightness test must be conducted on them. Therefore, the purpose of a gas tightness test is to check whether the sealing performance of the system meets the technical requirements, and to eliminate any detected leaks. 6.2 Technical requirements for airtightness ① The airtight system must be reliably isolated from external systems. ②The airtight pressure retention time shall be no less than 4 hours. ③The temperature and pressure of the system are recorded once per hour. ④The leakage rate is calculated using the following formula: Leakage rate = P1, T1: Absolute pressure and temperature at the start of the pressure testing; P2, T2: Absolute pressure and temperature at the end of the pressure testing; H: Pressure holding time (in hours). The standard for a leak-free system is that the leakage rate should be no more than 0.5% per hour on average. ⑤Ensure airtightness strictly in accordance with the airtight pressure rating to prevent overpressure in the equipment. ⑥The airtight pressure should be 1.05 to 1.1 times the system operating pressure, and it must not be altered without permission. ⑦When each system is airtight, cross-pressure is prevented to avoid the activation of safety valves. ⑧Seal surfaces such as flanges, manholes, and welds that have been accessed during maintenance should be tested for leaks using soapy water. ⑨All remaining items related to the gas fractionation unit have been rectified. 6.3 Preparations before airtightness testing ⑴ Use nitrogen as the airtightness medium, and prepare an adequate amount of nitrogen depending on the size of the device. ⑵Prepare pressure testing tools such as soapy water and a sprayer for inspection. ⑶Contact the company’s dispatch, instrumentation, and logistics teams to provide assistance. ⑷All vent points are properly closed, all systems are isolated and in a sealed state, and blind flanges have been installed on the inlet and outlet pipelines within the boundary area. ⑸On-site inspection shows that the pressure gauges are properly installed and in good working condition, and the instruments as well as the DCS pressure monitoring system are functioning normally. ⑹The system safety valve is in operation. ⑺The system division is based on the bottom extraction valve between adjacent towers as the boundary. ⑻The pressure gauges used for airtightness testing must have an accuracy of not less than grade 1.5, with ranges that fit the requirements; there should be no fewer than 2 such pressure gauges. 6.4 Classification of airtight systems: The equipment should have its airtight systems classified according to the operating pressure; different airtight systems have different airtightness pressures. Under normal circumstances, the feed tank, tower, and reflux tank form an airtight system. The airtight system of the plant can be divided into: the feedstock system, the depropanization tower system, the deethanization tower system, the propylene tower system, the high-pressure gas system, and the low-pressure gas system. 6.5 Methods and steps for airtightness testing: (1) Assign responsibilities clearly; assign specific persons to introduce nitrogen gas, monitor the pressure gauge, check for leaks using soapy water, and keep records. ⑵Airtightness testing should be carried out in stages according to the pressure levels of various systems in the device. Generally, it starts with the high-pressure system and proceeds in sequence. ⑶When performing a nitrogen leak test on the high-pressure system, it should be isolated from other associated low-pressure systems and pipelines; when testing the low-pressure system for leaks, nitrogen from the high-pressure system can be used to save nitrogen. ⑷The nitrogen pressure increase should be carried out slowly, with the test pressure set at the system’s maximum operating pressure. The pressure testing system should have at least two pressure gauges, with the gauge at the bottom serving as the primary reference and the gauge at the top serving as a secondary reference. ⑸Pressure boosting is generally carried out in two steps: in the first step, the pressure is raised to 50% of the airtight pressure, after which filling stops; the system is thoroughly inspected, and once no leaks are detected, the pressure is increased further. In the second step, the pressure is increased gradually to 10% of the airtight pressure, with each increase held for 30 minutes. Once the pressure reaches the maximum airtight value, filling stops; the pressure then needs to be maintained for 24 hours to allow for a thorough inspection of the system. Meeting the system air-shrinkage requirements indicates a successful pressure test. ⑹After the airtightness test is completed, the entire system shall undergo a tightness test at the specified pressure; it is required to maintain this pressure for 24 hours, with the system’s leakage rate being less than 0.5%. It is considered qualified within the specified range. Project Name, Normal Operating Pressure at the Top in MPa, Normal Operating Pressure at the Bottom in MPa, Pressure at the Start of Testing in MPa, Pressure at the End of Testing in MPa: Raw material tank system – 24 hours: 1.0, 1.0, 1.05; ≥0.95. Propane tower system – 24 hours: 2.03, 2.05, 2.15; ≥1.97. Ethane tower system – 24 hours: 2.55, 2.60, 2.73; ≥2.44. Propylene tower system – 24 hours: 2.00, 2.09, 2.19; ≥2.00. ⑺ After the airtightness test is completed, the system pressure is reduced to 0.1–0.2 MPa to prevent air from entering the system. 6.6 Requirements for airtightness testing: (1) The airtightness testing pressure must be applied strictly at the specified level; overpressure is not allowed. ⑵If a leak is detected during the airtightness testing process, the testing must be stopped immediately; in principle, the approach to take is determined based on the nature of the leak. ⑶The airtightness check must be carried out carefully and meticulously, ensuring that not a single sealing point is overlooked. ⑷The pressure increase and decrease during the airtight process should be carried out slowly. ⑸Airtightness inspection includes all sealing points such as equipment, pipelines, flanges, valves, pressure gauges, level gauges, and instrument thermometer casings. ⑹Airtight re-purging of the process pipelines and equipment, as well as water flushing and water commissioning, are carried out after they pass the relevant tests. The torch line pipelines, high-pressure and low-pressure gas line systems are made airtight together with the gas fractionation unit, while the low-pressure steam system is made airtight using low-pressure steam. ⑺During the airtightness testing, the pump, control valve, and flow meter must be connected together. ⑻During the airtightness testing process, the bypass valve should be opened first, followed by the manual valves before and after the control valve and flow meter. ⑼The pressure increase should be done gradually, with the rate of increase controlled to no more than 0.5 MPa/h. After each increase of 0.5 MPa, the pressure should be held stable for about 30 minutes (depending on the inspection results); only after it has been confirmed that there are no leaks in the system’s equipment and pipelines can the pressure be increased further. Once the system’s airtight pressure reaches the stable level, check for leaks at the pressure-stabilizing flanges, manholes, and static sealing points. ⑽Since the operating pressures of various devices vary, airtightness testing must be carried out in stages. ⑾When airtight, the heat exchanger should have a vent line, and care should be taken to check for leaks between the tubes and the shell. ⑿When airtightness testing is required, contact the electrical and instrumentation workshop to have the instruments tested for airtightness along with the system. Check the construction quality; slowly release the pressure after ensuring airtightness. 6.7 Safety precautions for airtight systems: (1) Before introducing an airtight medium into the system, carefully examine the process and prepare the valves to prevent high pressure from entering the low-pressure system; low-pressure equipment must be opened to allow air to escape. ⑵For equipment, instruments, and pipelines that cannot be included in the airtight system due to differences in pressure or other reasons when it is in an airtight state, blind flanges should be used for isolation, along with clear markings. ⑶If a leak occurs during the airtightness testing, pressure must be relieved before proceeding with repairs. It is not allowed to treat leaks under pressure. ⑷A detailed blind plate list must be available when the system is airtight. Chapter 7 Nitrogen Purging Scheme 7.1 Purpose of Nitrogen Purging To remove residual moisture from the drying process pipelines and equipment. Set the system dew point to -10ºC—-15ºC. Replace the air in the process lines and equipment to reduce the oxygen content in the system to less than 0.5%, in preparation for introducing liquefied gas. Further improve technical training to ensure that operators are familiar with the processes. 7.2 Safety precautions for nitrogen purging ⑴ Before introducing nitrogen, contact the dispatch team to confirm the timing and allowed amount of nitrogen to be used. ⑵The replacement principle generally involves multiple pressurizations and depressurizations of the system, along with sampling at multiple points for analysis. ⑶The equipment and pipelines connected to other positions need to be clarified during replacement. ⑷The temporary blind plate installed during airtightness testing should be removed. ⑸Before replacing the pipeline connected to areas outside the boundary, it is necessary to coordinate with the relevant departments and obtain their confirmation before proceeding with the nitrogen replacement together. ⑹After the replacement is successful, the system is pressurized with nitrogen at 0.1–0.2 MPa (G). ⑺Once nitrogen is introduced into the device, it is strictly prohibited for station personnel and maintenance staff to enter the tower or tank. 7.3 Criteria for successful nitrogen purging: Samples are taken from the top and bottom of the system, or at representative locations; the system is considered to have been successfully purged if the oxygen content in all sampled points is less than 0.5% (v). 7.4 Nitrogen displacement procedure ⑴ Displace air in accordance with the production process sequence. ⑵All connecting valves in the system, as well as the inlet and outlet valves of all pumps, should be opened. ⑶During replacement, all equipment, control valves, auxiliary lines, safety valve bypass lines, instrument lines, drain lines, and vent lines must be addressed in turn, ensuring no dead corners are left. ⑷Open the various low-point discharge valves and vent valves to release gas, until the oxygen content and system dew point meet the required levels as determined by analytical testing. ⑸After nitrogen purging of the equipment and pipelines is complete, the pressure should be maintained at 0.1–0.2 MPa (G). 7.5 Nitrogen Purging Procedure Chapter 8 Liquid Gas Feeding and Commissioning Plan Chapter 9 Emergency Response Procedures