Original methanol startup plan (including catalyst heating and reduction)

1.1 Preparations before starting the machine ① Verify that the following preparations have been completed: a) Installation of equipment and pipelines; b) Hydrostatic testing of pipelines; c) Purging and drying of equipment and pipelines; d) Boiling out of the waste heat boiler; e) Loading of the catalyst; f) Nitrogen leak test. ② All valves on the equipment and pipelines are in their correct positions and in the appropriate open/closed state. Pipeline blind flanges are installed in the right places, and temporary filters as well as blind flanges have been removed. ③ The instruments and interlock systems have been calibrated successfully and are functioning properly. ④ The following utility services have been supplied as required: a. Cooling water b. Nitrogen c. Steam d. Instrument air e. Electricity. ⑤ The oil washing, individual testing, and sealing tests of the compressor have been completed, and it is now ready for operation. 1.2 Pre-driving preparation checks ① Check and confirm that all valves are in the closed position. ② Check and confirm that all control valves are under proper control, can be operated freely, and that the valve positions shown on the control panel match those on-site. ③ Check to confirm that all interlocks and control valves have been tuned. 1.3 Steps for Starting the Machine 1.3.1 Nitrogen Purging 1.3.1.1 Nitrogen Purging Process Nitrogen is introduced from pipeline N327001 → V2701 → the shell side of E12701 → the tube side of E2705 → R2701 → the tube side of E2703 → the tube side of E2704 → the tube side of E2701 → the tube side of E2702. From there, it goes to V2703 → PV2721 for discharge → V2702 → T2701 → PV2733 for discharge. 1.3.1.2 Checking the Opening/Closing Status of Valves ① Close HV2731, HV2732, HV2733, HV2734, PV2721, LV2722, LV2731, FV2734, PV2733, as well as their bypass valves and upstream/downstream isolation valves. ② Manually slightly open LV2721, TV2717, and TV2719, and open their front and rear isolation valves as well as their bypass valves. ③ Open the process gas isolation valves before and after V2701, E2703, E2704, and E2705, and slightly open their bypass valves. ④ Open the discharge valves and backwash valves of each device and pipeline one by one to check for any accumulated water, and then close these discharge valves, backwash valves, and analysis sampling valves. ⑤ Open the root valves of each instrument and the root valve of the safety valve. 1.3.1.3 Methods and steps for nitrogen displacement: ① Replace PG27308 with a pressure gauge having a range of 0∽1.0 MPa, and open its root valve; N2 is introduced into the synthesis loop from the N227001 pipeline. ② Charge the synthesis loop pressure to 0.4∽0.5 MPa. ③ Release the synthesis loop pressure to 0.05 MPa by opening PV2733, PV2721, and their bypasses. ④ After several cycles of pressurization and depressurization, samples were taken at points S2703, S2702, S2705, and S2706 for analysis. A result of O2 ≤ 0.2% was considered acceptable. At the same time, appropriate discharge was carried out at each drain and release valve to prevent the formation of dead zones. Once the displacement was complete, the synthesis circuit was maintained at a pressure of 0.5 MPa. ⑤ The replacement of C2701 and C2702 is carried out separately. a. Confirm that HV2733 and HV2734 are turned off. b. Fill C2701 with nitrogen from the C2701 nitrogen filling valve until the pressure in the compressor system PI2754 reaches 0.5 MPa. c. Reduce the pressure in circuit C2701 to 0.05 MPa by opening the drain valves of HV2732 and cylinder C2701. Repeat this several times, then slightly open the bypass valve. d. Sample analysis is conducted through the cylinder’s drain; a result of O2 ≤0.2% is considered acceptable. At the same time, appropriate discharge is carried out at each drain and outlet valve to prevent the formation of dead zones; after the displacement is complete, the system is held at a pressure of 0.5 MPa. 1.3.2 Airtightness test 1.3.2.1 Verify the status of the system valves: ① HV2731, HV2733, HV2734 and their bypass valves must be fully closed. ② The inlet, outlet valves and bypass valves for TV2717, TV2719, V2701, E2703, E2704, and E2705 are fully open. ③ Turn off completely PV2721, LV2722, LV2731, FV2734, PV2733, as well as their bypass valves and the inlet and outlet isolation valves. ④ Slightly open LV2721 and open its front and rear isolation valves. ⑤ E2702A/B are connected to cooling water. ⑥ Replace PG27308 with a pressure gauge of the normal range. 1.3.2.2 Establish gas flow; use E2703 and E2704 to establish the liquid level. ① Open the N2 boundary valve, as well as the PV2721 and PV2733 bypass valves, to create the desired gas flow. Nitrogen is introduced from pipeline N227001 → V2701 → the shell side of E12701 → the tube side of E2705 → R2701 → the tube side of E2703 → the tube side of E2704 → the tube side of E2701 → the tube side of E2702. V2703 → PV2721 for discharge → V2702 → T2701 → PV2733 for discharge. ② Open the boundary valves of the boiler feedwater synthesis section, as well as LV2711, LV2713 and the isolation valves before and after them, to establish a liquid level in E2703 and E2704. ③ After completing the airtightness test on the system at 0.5 MPa, close LV2721 and its bypass valve as well as the upstream and downstream isolation valves, isolate V2703, and then conduct an airtightness test at a pressure level higher than 0.5 MPa. ④ During the pressurization process, the system was checked for leaks at 1.0 MPa, 3.0 MPa, and 5.5 MPa respectively; if a leak was detected, the N2 isolation valve was closed and PV2733 was opened to monitor PG27308, with the system pressure being reduced at a rate of 0.3 MPa/min until the leak stopped. Contact the maintenance personnel to carry out the necessary repairs, then increase the pressure and try again until there is no leakage. ⑤ Note: Before raising the system pressure, it is necessary to close the valves connected to the low-pressure system to prevent high pressure from entering the low-pressure system. 1.3.2.4 System pressure reduction: After the airtightness test is completed, open PV2733 and monitor PG27308; reduce the system pressure at a rate of 0.3 MPa/min until it reaches 2.0 MPa, then start the compressor in accordance with the operating procedures for the cycle air compressor. 1.3.3 Starting up the circulating gas compressor 1.3.3.1 Airtightness of C2701 1.3.3.2 Starting up C2701 1.3.4 Heating and reduction of the catalyst The specific procedures for heating and reduction depend on the type of catalyst used, and shall be carried out in accordance with the supplier’s requirements; the following are some specific operations related to heating and reduction: 1.3.4.1 Preparation work ① The piping required for the reduction process has been installed. ② The cycle gas compressor is in normal standby mode after testing. ③ The airtightness test of the synthesis loop passed. ④ Nitrogen, reducing gas, start-up steam, cooling water, and boiler feedwater are available in good condition. ⑤ All instruments under this work order have been calibrated successfully, offering sensitive and accurate responses. ⑥ Barrels, weighing scales, hoses, gas protection and personal protective equipment, as well as fire-fighting equipment are all ready. ⑦ Analysis is ready. ⑧ The system valves are in the correct position, with no internal leakage. ⑨ Replace the system with nitrogen until O2 ≤ 0.2%, then complete the replacement. 1.3.4.2 Commissioning of E2702, E2703, and E2704: ① Before starting C2701, fill E2703 and E2704 with BW. The water filling must be carried out slowly to prevent fluctuations in the pressure of the boiler feedwater network; once the liquid level reaches 50%, switch to automatic control of the liquid level. ② Start the dosing unit Y2701, adjust the flow rate to around 0.9 L/h, and inject chemicals into E2703 and E2704. ③ During engine startup, the bottom drains E2703 and E2704 should be opened to keep the liquid level in the waste boiler within the normal range. ④ Open the top exhaust valve of E2702A/B and the water supply valve to exhaust air from the water cooler first. After exhaust is complete, open the feed water and return water valves to put the water cooler into operation. ⑤ Note: During the catalyst heating and reduction process, it is necessary to strictly adhere to the temperature control parameters specified in the \"Catalyst Heating and Reduction Plan\". When the temperature of the catalyst bed does not meet the requirements, it can be adjusted using TV2717, TV2719, PV2711, and PV2733. 1.3.4.3 Heating and reduction of the catalyst: a. Activate E2705, open the drain valve of E2705 to remove all the condensate water from the heat exchanger until no water hammer occurs; after thoroughly warming up the heat exchanger, close the drain valve and activate the steam trap, then open the steam valve fully. b. Open the steam vent valves E2703 and E2704 at the site as appropriate, to establish steam flow from the by-product steam to their respective vent lines. c. As the catalytic reduction reaction proceeds, the temperature at the outlet of the synthesis tower increases further. When the steam generated by E2703 and E2704 meets the temperature and pressure requirements of the S3 and S4 pipelines, sampling for analysis is carried out. Once the SiO2, Na+, and conductivity levels of the steam are found to be within acceptable limits, it is sent to the S3 and S4 pipelines, and PICA2711 is set to 1.1 MPa to enable automatic operation. d. Raise the temperature of the synthesis system strictly in accordance with the catalyst’s heating and reduction protocol. ① The heating and reduction process must strictly adhere to the required rates of heating and reduction, and the principle of increasing temperature without increasing hydrogen concentration, and increasing hydrogen concentration without increasing temperature, must be firmly followed. ② Strictly control the water vapor concentration in the gas exiting the tower, and regulate the water discharge rate to ensure uniform discharge. ③ The water produced during reduction must be measured precisely and handled properly. ④ Throughout the reduction process, the starting steam pressure must remain stable, and the analysis of hydrogen concentrations at the inlet and outlet must be timely and accurate. ⑤ During the reduction phase, the hydrogen concentration at the inlet and outlet is analyzed every half hour, and the analysis data must be accurate and reliable. ⑥ During the heating and reduction process, it is essential to prevent the temperature of the catalyst bed from exceeding the specified limit. 1.3.5 Light-load production 1.3.5.1 After the reduction process is completed, gas introduction can be prepared once everything in the previous process is operating normally. 1.3.5.2 Verify the process parameters of the previous stage to ensure that the gas composition and total sulfur content meet the process requirements. 1.3.5.3 Once the temperature of the catalyst bed has stabilized at 210°C, fresh gas should be introduced slowly through the bypass valve of HV2731, at a pressure increase rate of 0.02 MPa/min; the pressure increase rate must not be too fast to prevent damage to the catalyst. 1.3.5.4 As the synthesis reaction proceeds, the steam flow rate of E2705 can be gradually reduced based on the temperature of the catalyst bed. Once the heat generated by the reaction is sufficient to maintain the bed temperature, the inlet and outlet valves for the E2705 steam as well as those for the process gas should be closed. 1.3.5.5 During the initial startup phase, crude methanol contains a high amount of impurities; a temporary pipeline is connected after the methanol separation tank to discharge this crude methanol into the waste oil tank. Sampling and analysis must be carried out continuously during this discharge process. Samples should be taken for analysis once the product becomes transparent and clear with no abnormal odors. Once the product meets the specifications, the drain valve should be closed, and LV2721 along with the isolation valves before and after it should be opened. The liquid level should be set at 30% and the system should be switched to automatic mode. 1.3.5.6 When the liquid level in the methanol expansion tank V2703 reaches 30%, open LV2722 and the isolation valves before and after it; automatic control is activated when the liquid level is set at 50%. 1.3.5.7 Adjust the load of the synthesis section as appropriate: operate at 60% load for 10 days, at 80% load for 5 days, and then increase it to full load. 1.3.5.8. When the synthesis system is operating stably, the old system is ready to receive the vent gas and distillation has already started, open FV2734 to establish a liquid level in T2701. Once LICA2731 reaches 30%, open the inlet and outlet valves for the process gas in T2701, open LV2731 along with its upstream and downstream isolation valves, set LICA2731 to 30% in automatic mode, and bring T2701 into operation. 1.3.5.9 Start and run C2702.

Preparations before startup: For a first-time startup of this process, a separate plan must be devised for purging the pipelines and equipment； Individual unit test and joint commissioning of the pump ； Airtightness test ； Cleaning and leak testing of the tube side, shell side, and drum of the synthesis tower ； Catalyst loading and other tasks. If starting up after maintenance, the aforementioned tasks related to the specific situation should be completed before starting up. Before driving, the company’s or branch factory’s production workshops should organize relevant personnel to conduct the following inspections of mechanical, electrical, instrumentation, and utility systems: 1. Check whether safety equipment is complete, such as oxygen respirators, filter masks, fire extinguishers, etc. 2. Check whether the associated equipment, pipelines, and valves are intact ； Check whether the installation, maintenance, and insulation work have been completed ； Check whether the valve operates smoothly and properly, and whether its switching position is correct. 3. Check that the electrical equipment and instruments are in good condition and in standby mode. 4. Check whether the pump has passed the trial run, inspect the quality and quantity of oil, and verify that the cooling water is in standby mode. 5. Check whether the safety valves in the system have been calibrated and whether their setting values meet the specified requirements. 6. Verify that the utility systems are ready, such as circulating water, demineralized water, electricity, low-pressure steam, N2, instrument air, H2 (or conversion gas), etc. 7. Check whether the insertion positions of all blind plates are correct. 8. Inform the analyst to make all necessary analytical preparations for starting up the synthesis process. 9. Obtain Na3PO4 and prepare a phosphate solution at a suitable concentration (around 5% wt) for later use. 10. Upon completion of work, exhaustion of materials, and clearing of the area within this process zone – Starting up the equipment: ㈠. Initial startup 1. System flushing: This includes the combined fresh gas and recycle gas compressor system as well as the synthesis system. ① Connect dry, oil-free N2 to the boundary zone to replace the qualified N2 system and put it in standby. ② Notify the fitter to remove the blind flanges from the N2 piping feeding the synthesis system, fresh gas, recycle gas inlets, and the two-in-one compressor inlet, in order to open up the pipelines. ③ Close all vent valves, sampling valves, and backwash valves of the synthesis system, as well as the discharge valves and bypass valves of the methanol separator, flash tank, and alcohol washing tower. ④ After confirming that the above operations are correct, start the synthesis system; close the N2 filling valve of the compression system, and pressurize the synthesis system for purging. ⑤ 2-in-1 compressor replacement: Open the synthesis system vent valve, sampling point, and backwash valve. ⑥ After pressurization, intermittent multi-point discharge is used to reduce the O2 level in the system to ≤0.1%. ⑦ After the high-pressure system has been successfully purged, open the separator alcohol release valve to force the purge into the flash tank. ⑧ The position of conversion and the pipelines in the distillation unit can be adjusted; it is possible to coordinate the replacement of related positions simultaneously, or the flange behind the valve can be removed for separate replacement. ⑨ When it is not possible to vent to the flare system, replacement can be achieved through on-site venting. 2. Valve setting and system pressurization: ① Close all vent valves, backwash valves, and sampling valves in the synthesis system ； Close the backwash valve and vent valve of the 2-in-1 compressor system for compression tasks ； Isolation valves before and after the control valve, as well as bypass valves ； The operator manually shuts off the aforementioned control valve to prevent accidents during operation. ② The N2 filling valve for the synthesis and compression stations is used to pressurize the system to 0.5–0.65 MPa. 3. Establish the N2 cycle: ① Inform the compression team to use the two-in-one compressor to create a N2 cycle in the synthesis system, and maintain an empty space velocity of 1000–1500 h-1 in the synthesis tower. ② When the circulation volume is significantly low, open the N2 filling valve to supply N2 to the system. It should be noted that each time N2 is added, it must be tested to ensure it is of qualified quality, dry, and free from oil contamination before introduction. 4. Establish the drum liquid level: ① Open the drum vent valve, and close the drum drain valve as well as the shell-side drain valve of the synthesis tower. ② Open the root valve of the drum pressure gauge, as well as the vapor-liquid phase valve for on-site and remote level gauges. ③ Close the steam inlet isolation valve of the spray needle, and close the steam outlet isolation valve of the steam drum. ④ Close the spray needle backflow valve, open the methanol water cooler and the drum sampling cooler, as well as the return water valve for the cooling water of the syngas sampling cooler. ⑤ Contact the conversion team to start the boiler feed pump and supply water to the steam drum. The main control system manually operates the control valve to maintain a drum liquid level of 50%, after which automatic control is engaged. ⑥ Contact the dispatch to supply medium-pressure steam to warm the pipes and keep them ready for use. ⑦ Start the phosphate dosing unit to continuously and quantitatively add phosphate solution to the synthesis drum until the boiler water meets the specified standards. 5. Catalyst heating and reduction: ① Start the two-in-one compressor, and activate the start-up injector to use medium-pressure steam from the pipeline network to heat the catalyst. ② The heating rate of the synthesis tower is controlled by adjusting the opening degree of the start-up ejector steam cut-off valve, with the heating rate to be ≤ 25°C/h (or in accordance with the \"Heating and Reduction Plan for Synthetic Catalysts\"). And inform the fitter to open the blind flange on the reduction conversion gas pipeline, so that the conversion gas can be made available for use after passing the analysis. ③ Before heating the catalyst for reduction, a hydrogen dosing test must be conducted. The procedure is as follows: open the hydrogen dosing valve and supply hydrogen to the system at rates of 5 m3/h, 10 m3/h, and 20 m3/h respectively; take samples at the inlet and outlet of the synthesis tower to analyze the hydrogen concentration, and keep records of these values. Finally, purge the system with N2 to ensure it is clean enough. The purpose of this is to provide a basis for controlling the hydrogen supply during catalyst reduction. ④ When the outlet temperature of the synthesis tower rises to 100°C and remains at this level for 4 hours, all the water adsorbed by the catalyst is removed. The amount of physical water separated out in the methanol separator is measured by weighing, and this value is comparable to the theoretical amount of water produced. Once the liquid level in the methanol separator stabilizes and no more physical water is separated out, the constant-temperature phase comes to an end. ⑤ The exit temperature of the synthesis tower is raised to 120°C for hydrogen addition; both the hydrogen concentration and the rate of temperature increase are strictly controlled in accordance with the \"Synthetic Catalyst Temperature Raising and Reduction Plan\". ⑥ Notify the analyst to analyze the (CO+H2) content in the feed gas and recycled gas every half hour, and to analyze the CO2 content every 2 hours. ⑦ Until the outlet temperature of the synthesis tower is raised to 230°C, chemical water is drained 1–2 times per hour from the bottom of the methanol separator, and the volume measured and recorded. ⑧ Maintain the temperature of the synthesis tower at 230°C and gradually increase the hydrogen concentration; when the hydrogen level remains unchanged for three consecutive times and the water output ceases to increase, it can be considered that the reduction process is complete, at which point the hydrogen addition valve should be closed. ⑨ Compare the temperature rise reduction curve with the theoretical curve to determine whether the reduction is complete. ⑩ After it is determined that the reduction process is complete, steam from the injector is used, along with control of the pressure in the synthesis vessel, to reduce the temperature at the outlet of the synthesis tower to 210°C. The pressure in the synthesis system is then maintained at around 0.65 Mpa, in preparation to receive syngas. 6. Precautions during the heating and reduction process: ① Strictly control the content of toxic substances in the reducing gas: O2 should be less than 0.10%, NH3 less than 200 ppm, sulfur content less than 0.1 ppm, CO2 less than 15%; there should be no oxides, oil mist, or unsaturated hydrocarbons present. ② During the reduction process, the principles of “three lows, three stabilities, and three no’s” must be followed. That is, the “three lows” refer to: low-temperature effluent, low-temperature reduction, and a period of low-load operation after reduction ； “The “three stabilities” refer to stability in temperature increase, stability in hydrogen supply, and stability in water output ； “The “three no’s” refer to not carrying out hydrogen addition and temperature increase simultaneously, not allowing moisture to enter the tower, and not allowing the high-temperature water to remain inside for too long. ③ Gas analysis must be conducted promptly and accurately throughout the reduction period: the difference between the inlet and outlet values of the synthesis tower (H2+CO) should be around 0.5%, with a maximum value of ≤1.0%. ④ During the reduction process, the N2 or conversion gas to be added to the system must be analyzed; it must pass the tests before it can be introduced. ⑤ The reduction temperature is up to 230°C. ⑥ If the temperature rise in the catalyst bed becomes too rapid, immediately shut off the hydrogen supply valve, reduce or completely close the steam injector to maintain a stable bed temperature, lower the pressure in the synthesis drum, increase wastewater discharge, and add low-temperature boiler water to the drum. If the circulation pump fails, pressure relief and filling with N2 can be used to reduce the amount of reducing gases. ⑦ When the CO2 level in the circulation loop is greater than 5%, the vent volume should be increased, and the N2 supply valve should be opened to remove the excess CO2.