Thread Content
This post was last edited by Xin Ruifangxiao on 2023-3-9 at 17:00. Proper equipment layout can improve production efficiency, ensure product quality, and at the same time enhance the efficiency of equipment maintenance as well as the safety of workers. Piping layout design is also an important component in chemical plants; it is directly related to the flow, reactions, and control of substances. Therefore, it must be carefully designed and installed to ensure the stability and safety of the production process. Today is the final installment of our series on chemical plant equipment and installations; let’s take a look! 25 The layout diagram of equipment ports should indicate not only the ports themselves, but also, in addition to the ports for process and utility media, the following: 1. The location of instrument connections, including those for temperature, pressure, and level ； 2. Location of manholes, handholes, and suspension columns, location of skirt base exhaust vents ； 3. Orientation of the equipment’s foundation bolt holes or the orientation of the brackets ； 4. Position of lifting lugs, grounding plates, and nameplates ； 5. Location of internal ladders and reinforced supports at the bottom of the skirt. 26 To determine the fixation of the supports for horizontal vessels, identify the pipe among those that need to be connected to the vessel that is most important for flexible calculation purposes (i.e., the one with the highest requirements), such as a pipe with large compensation needs or a large diameter, and use this as a basis for deciding on the type of support. The position of the fixed side support should facilitate the flexible calculation of the pipeline. 27 Requirements for the orientation of the openings on horizontal containers 1. The distance between the liquid inlet and outlet on the equipment housing should be as large as possible. The liquid inlet pipe should be kept as far away as possible from the container level gauge interface ； 2. The level gauge interface should be located in a position that is easy for the operator to observe and maintain. Sometimes, to reduce the number of connections on the equipment, measuring devices such as local level gauges, level controllers, and level alarms can be installed on the manway. The orientation of the level gauge outlet should be on the same side as the liquid level control valve assembly ； 3. Manhole covers connected by hinges (or suspension posts) should not interfere with other pipe openings or pipelines when opened ； 4. The safety valve connection port should be located at the top of the container. 28 General requirements for piping layout of horizontal vessels. The piping for containers (tanks) is relatively simple; the piping layout for vertical vessels is generally similar to that of towers, with piping designed along the tank walls. Valves on the piping should also be connected directly to the openings, thereby preventing the accumulation of liquid. When arranging horizontal container equipment, the tank is generally placed perpendicular to the long axis of the pipe tray; as a result, pipes such as gas outlet pipes, safety valve outlet pipes, and liquid outlet pipes all face the pipe tray and are connected to the relevant components on it ； The supervisors are connected. The pipe emerging from the opening at the top of the container should be at a higher elevation than the main pipe it is connected to in the pipe tray, so as to allow it to be connected to the top of the main pipe. When the liquid outlet pipe at the bottom of the container is connected to the pump located beneath it, the elevation of the bottom of that pipe should not prevent people from passing by. 1. For the pipeline connecting the liquid outlet of a horizontal container to the pump inlet, if the piping is installed above the channel, the minimum clear height required is 2200 mrn ； 2. For the pipeline connected to the bottom outlet of a horizontal container, the minimum clear height from the floor to the lowest liquid discharge point is 150 mm ； 3. When the outlet of the safety valve is connected to a closed pipeline system, accumulation of liquid should be avoided. The outlet pipe of the safety valve should be angled 45° downward in the direction of flow of the medium, connecting to the top of the main closed pipe, without any \"pouch-like\" formation. If the safety valve is installed far away from the container, it is necessary to verify the pressure drop in the pipeline from the container to the safety valve inlet ； 4. The control valve assemblies for the pipes at the top of the storage tank are located on the platform ； 5. Platforms should be installed according to the layout of equipment and pipelines. 29 General requirements for the piping layout design of heating furnaces 1. The piping layout of a heating furnace varies depending on its type; when designing such piping, consideration should be given to its feed and discharge pipes, fuel system pipes, soot-blowing gas pipes, fire-suppression steam pipes, etc., as a whole ； 2. The inlet and outlet main pipes for the cylindrical furnace are usually arranged in a circular pattern around the furnace body, and can be supported on the ground or the furnace body itself. The ring main pipe should be located above the sight glass to facilitate its proper operation and maintenance ； 3. At the furnace outlet pipe elbow if necessary. Anti-vibration supports should be installed at the three-way connections or where there is a significant change in diameter, or at the bottom part extending vertically downward from the top of the furnace ； 4. If a rupture disc is installed in the pipeline, its direction must not face the operating area or the equipment ； 5. The main control valve assemblies are usually installed between the pipe gallery and the furnace, with attention paid to the requirements regarding access pathways ； 6. Valves on steam, fuel oil, or fuel gas pipelines should be installed on vertical pipes near the viewing ports, to meet the requirements for regulation and maintenance ； 7. In cold regions, steam tracing should be applied to fuel oil pipelines in accordance with regulations ； 8. The pipes near the nozzle should have a detachable connection structure to facilitate cleaning and maintenance ； 9. Platforms and ladders should be provided at valves and viewing points that are frequently accessed and located at higher positions ； 10. The discharge points for fuel pipelines should be at least 15 meters above the furnace, and they must be connected to a collection system; they cannot be discharged directly into the sewer system ； 11. The pipes connected to the furnace should be arranged as closely together as possible to facilitate support and achieve consistency. For aesthetic purposes ； 12. For the feed pipes of the heating furnace, it is necessary to maintain uniform flow rates in each channel ； For fully liquid-phase feed pipelines, flow control valves are generally installed in each branch to regulate the flow rate in those branches; otherwise, the pipelines should be arranged symmetrically. For pipes for the inlet and outlet of gas-liquid mixtures, a symmetrical arrangement is necessary to ensure that the pressure drop across each branch is the same ； 13. The annular oil line should have its thermal compensation calculated based on the maximum temperature, with the natural expansion of the pipeline being used to absorb its thermal expansion. 30 General requirements for the layout of fuel gas pipelines in heating furnaces (1) A main distribution pipe for fuel gas should be provided to ensure uniform distribution of fuel gas to each nozzle ； The fuel gas branch pipe extends from above the main distribution pipe to ensure that the fuel gas entering the nozzle does not contain water or condensed oil. At the end of the main fuel gas distribution pipe, there is a DN20 drain valve to facilitate drainage during commissioning and flushing, as well as after shutdown for line cleaning; it is also used for sampling and analyzing the oxygen content in the pipeline during startup. Two drain valves should be installed on the drainage pipe to prevent leaks, and these valves can be operated from the ground or the platform. The main fuel gas cut-off valve should be located at a distance of 15 m from the heating furnace. (2) Installing a flame arrester on the fuel gas pipeline can prevent the spread of flames. Based on their working principle, flame arresters can be divided into dry-type flame arresters and safety water seals. Dry type flame arresters with multiple layers of copper wire mesh are generally used on the fuel gas pipes of heating furnaces in industrial production facilities. The flame arrester should be placed near the nozzle. The distance between the pipe flame arrester and the burner should not exceed 12 m. In this way, the flame arrester is not exposed to severe explosion conditions, allowing its service life to be extended. 31 Pipe layout in shell-and-tube and double-pipe heat exchangers 1. When arranging the process pipes, attention should be paid to the flow direction of the cold and hot streams; generally, the cold stream flows from bottom to top, while the hot stream flows from top to bottom ； 2. The piping layout should facilitate operation and not hinder the maintenance of the equipment ； 3. The base elevation of the heat exchange equipment shall ensure that the drainage pipe beneath it is at a distance of not less than 150 mm from the ground or platform surface ； 4. In the pipes of heat exchange equipment, there should be only one high point and one low point to prevent the formation of air pockets or liquid pockets along the length of the pipes; a vent should be provided at the high point and a drain at the low point ； Within the heat exchange equipment area, pipeline intersections and detours should be avoided as much as possible ； Minimize the number of layers for overhead pipelines; generally, 2–3 layers are sufficient ； 5. The inlet pipes of two or more heat exchange units connected in parallel should be arranged in direct symmetry; for heat exchange units dealing with gas-liquid two-phase flow, symmetrical arrangement is necessary to achieve good heat transfer performance ； 6. The measuring instruments on the inlet and outlet pipes of heat exchange equipment should be installed near the operation passage and in locations where they are easy to observe and maintain ； 7. For pipes of condensable media connected to heat exchange equipment, or for pipeline branches containing solid particles, their isolation valves should be installed on horizontal pipes, and measures should be taken to prevent the accumulation of liquid in dead corners ； 8. In cold regions, the supply and return pipes of outdoor heat exchange equipment should be equipped with drain valves and anti-freezing bypass pipes. 32 For heat exchange equipment arranged in groups, how should the piping layout be designed? When arranging the equipment, it is necessary to take into account the requirements for construction, maintenance, operation, and fire safety, and to provide adequate passages and areas as needed. Inside the facility, application roads divide it into equipment and building areas with a floor area not exceeding 10,000 m2. When the floor area of the esterification polymerization, spinning, and post-processing facilities for synthetic fiber production exceeds 10,000 m2, passageways should be installed on both sides of them. The main traffic passage within the facility should be connected to the factory roads. 1. The installation of fire access routes in the facility shall meet the following requirements: (1) When the width of the facility exceeds 60m, a continuous fire access route shall be provided within the facility ； (2) When the device’s width is 60 m or less and there are fire access routes on both sides of the device, a continuous fire access route may not be required. Non-through roads within the facility should be provided with turnaround areas. (3) The width of the road should not be less than 4 m; the clear distance between the pipe rack on the road shoulder and the edge of the road surface should not be less than 1 m. The internal turning radius of the road surface should not be less than 7 m, and the clear height above the road surface should not be less than 4.5 m. 2. The maintenance access road should meet the requirements of mechanical tools used for maintenance in terms of road width, turning radius, and load capacity, and should lead to the lifting holes for equipment maintenance. 3. The main vehicle passages, fire access routes, and maintenance passages within the facility should be arranged together. 4. The operation pathways should be determined based on the frequency of production operations, routine inspections, minor repairs, etc., as well as the distribution of the operation points. 33 Requirements for pipeline layout in vertical reboilers: 1. The pipelines must have sufficient flexibility to compensate for the thermal expansion of the equipment and pipelines under various operating conditions ； 2. When the outlet of the reboiler is connected to the outlet of a pipe in the same tower, and if the load conditions permit, it is advisable to install supports on the tower to hold the reboiler; moreover, the location and design of these supports should be such as to accommodate the displacements and loads resulting from the expansion of the tower and its pipes ； 3. When installing the piping, space should be left to allow for the removal of the reboiler bundle in place ； 4. For one-pass fixed-tube-sheet heat exchangers with expansion joints on the shell, the impact of these expansion joints should be taken into account when carrying out piping work, flexible analysis, and support design for the equipment ； 5. When the length-to-diameter ratio (L/D) of the reboiler is greater than 6.0, guide supports should be installed ； 6. When the valves and blind flanges of the reboiler are more than 3 m above the ground, a platform should be installed on the tower. 34 Requirements for piping layout of shell-and-tube horizontal reboilers: 1. Within the allowable stress range due to thermal expansion, the downcomers and steam generators of the reboiler should be made as short and straight as possible, with as few elbows as possible, in order to reduce pressure drop ； 2. When the reboiler has two vapor rise ports, to ensure equal flow within its tubes, the vapor rise ports should be arranged symmetrically. When the diameters of the steam rise pipes differ and their arrangement is asymmetric, efforts should be made to make the resistance of these two pipe sections equal. Otherwise, the low flow rate in the steam rising pipe due to high resistance will result in uneven heat distribution ； 3. The liquid drawn out from the reboiler is a saturated liquid; if a pressure drop occurs in the piping system, the liquid will begin to flash, resulting in a two-phase flow of gas and liquid, which affects the operation and accuracy of control and measurement instruments. Therefore, when installing pipes for saturated liquid, the basic principle is to minimize pressure drop, and to avoid any vertical upward sections before the measuring or control instruments ； 4. The inlet pipeline for the heating medium in the tube side of the reboiler is usually equipped with a temperature control valve and its associated valve assembly; these valves are generally installed on the floor or platform near the inlet to the tube side of the reboiler. 35 Specific requirements for the piping design of air coolers: 1. For the oil and gas pipelines from the top of the distillation tower to the air cooler, it is generally not advisable to have \"liquid pockets\". When there are no valves at the inlet and outlet of the air cooler or when a two-phase flow exists, the pipes must be arranged symmetrically to ensure uniform flow through each section of the air cooler ； 2. The inlet manifold of the air cooler should be connected close to the nozzles of the air cooler; if stress conditions or installation requirements dictate otherwise, the outlet manifold may not need to be connected close to the nozzles. The cross-sectional area of the manifolds should be greater than the sum of the cross-sectional areas of the branch pipes ； 3. When the air cooler inlet is filled with a gas-liquid two-phase flow, each branch pipe should be inserted into the inlet manifold from below ； To ensure uniform distribution of the fluid at the bottom of the collecting ducts ； At the same time, a shutdown drainage pipe is installed below the collecting duct, connected to the outlet pipe of the air cooler ； 4. The inlet pipe of the air cooler is at a high level ； If the distance is large, a dedicated pipe rack must be installed in between to support the pipes ； 5. The softened water return system of the wet air cooler is a gravity-fed pipeline; therefore, attention should be paid to the layout of the piping system, and there should not be too many bends. The return main should have a slope in the direction of flow of the medium ； 6. A semi-fixed steam purging connector is provided on the operating platform of the air cooler; its valve should be located in an easily accessible position, and care must be taken to consider the direction of the steam connector to ensure safe operation. 36 General requirements for the piping design of pumps 1. Cut-off valves should be installed on the inlet and outlet pipes of the pump, and the pipes must have sufficient flexibility in order to reduce the stress and torque exerted by the pipes on the pump’s outlet ； 2. The suction pipeline of the pump must meet the pump’s requirement for \"netsuction head\"; the pipeline should be as short as possible, with few bends, and free of air pockets. If it is unavoidable, a vent valve should be installed at the high point ； 3. When the pump suction pipe is long, it is advisable to give it a certain slope (i=5‰) ； When the pump is lower than the container, it is advisable to have a slope leading toward the pump; when the pump is higher than the container, it is advisable to have a slope leading toward the container ； 4. A filter or temporary filter should be installed just downstream of the pipeline shut-off valve at the pump inlet, and a check valve should be installed at the pump outlet to prevent the reverse flow of fluid and thus the reversal of the pump’s impeller ； 5. The pump piping, provided that the process requirements are met. The valve handwheel must not interfere with the normal operation of the pump or with the space required for maintenance and inspection ； 6. The design of the inlet and outlet pipes of reciprocating pumps should take into account the effects of fluid pulsation. 37 What are the types of protection wires for pumps? What is its function? There are 6 types of protection lines for pumps, and their purpose is to prevent damage to the pump and ensure its proper operation; the protection lines for pumps are selected based on the operating conditions. 1. Warm pump line – When transporting high-temperature oils with a temperature exceeding 200°C, a DN20–25 warm pump line should be installed in the presence of a backup pump ； 2. Low-flow line – When the pump’s operating flow rate is 30% below its rated flow rate, a low-flow line should be provided to allow the pump to operate normally at that lower flow rate ； 3. Balance line – For liquids whose saturated vapor pressure at room temperature is higher than atmospheric pressure, or liquids that are in the bubble point state, a balance line must be installed to prevent vapor from forming in the liquid entering the pump or bubbles from entering the pump and causing cavitation ； 4. Bypass line – used for the trial operation of the pump, or to keep the pump running when the main outlet valve is closed under abnormal operating conditions. Bypass valves equipped with flow-limiting orifices are generally installed in situations where the pressure difference before and after the valve is very high ； 5. Anti-freezing measure – When transporting liquids with a high pour point or high freezing point that solidify at normal temperatures, anti-freezing measures should be implemented for the standby pumps and pipelines to prevent them from getting clogged ； 6. Safety valve line – For positive displacement pumps such as electric reciprocating pumps, gear pumps, and screw pumps, a safety valve line is provided on the outlet side; when the outlet pressure exceeds a set value, the safety valve opens and the fluid returns to the pump inlet pipe. Application of Fle*ngSeal expanded PTFE sealing strips on pumps 38 General requirements for the piping layout of centrifugal compressors 1. There are two types of centrifugal compressor housings: the vertically split type is used for high-pressure applications, and there should be no pipes or other obstacles in front of the compressor ； The horizontal split type is used for medium and low pressures; there must be no pipes or other obstacles above its mechanism ； 2. The layout of the inlet and outlet pipes should, while meeting the requirements for thermal compensation and allowable stress levels, minimize the number of elbows in order to reduce pressure drop ； 3. The inlet and outlet nozzles are generally oriented downward and supported at the center of the machine housing; during operation, their thermal expansion should be absorbed by the pipes ； 4. When the compressor nozzles in the factory are arranged for inlet and outlet at the top, detachable adapters must be installed on the inlet and outlet pipes to facilitate compressor maintenance. 39 General principles for the piping layout design of reciprocating compressors 1. The inlet and outlet pipes of the compressor should be short and straight, with as few elbows as possible; however, when the outlet pipe expands due to heat, the pipe should be made flexible ； 2. The pipeline layout should take into account the natural flow of the liquid to the liquid separation tank; when a \"liquid pocket\" forms in the pipelines, a drain at the lowest point should be provided to empty it ； 3. When multiple units are arranged side by side, the valves and instruments on their inlet and outlet pipelines should be installed in locations that are easy to operate and access ； 4. To prevent vibration in the inlet and outlet pipes of the compressor, necessary vibration analysis should be conducted. The pipeline layout should be as low as possible; the supports should be placed on the ground and use independent foundations, in order to increase the rigidity of both the supports and the pipelines ； 5. When the medium in the compressor is a flammable gas, plug plugs, pipe caps, or flange covers should be installed on the drain valves at the lowest points of the pipes and on the vent valves at the highest points to prevent leaks. Additionally, sand should be filled in the trenches surrounding the unit to avoid the accumulation of flammable gases ； 6. When installing the inlet and outlet pipes of the compressor, it should not interfere with the movement of the maintenance crane ； 7. The pipes of the compressor should be arranged below the operation platform, to provide ample space around the unit for operation and maintenance. That’s all for our sharing on the layout requirements for common equipment in chemical plants! See you next time! Disclaimer: The content contained herein is sourced from public sources such as the Internet and WeChat official accounts. We maintain a neutral stance regarding the views expressed in it; these views do not represent those of this official account. All articles are provided for reference and informational purposes only. If there is any infringement, please contact us to have it removed.