Piping arrangement in petrochemical plant
In petrochemical plant, pipelines with different operation parameters and transmission medium properties are quite different, and their importance and risk are also different. In order to better ensure the reliability and safety of pipelines in the operation process, different design, manufacturing and construction requirements are proposed for pipelines with different importance.
Determination of pipeline design conditions
The design pressure of petrochemical pipeline and its components shall not be lower than the pressure under the most severe conditions combined by internal pressure and temperature during operation.
1. The design pressure of all pipelines connected with equipment or pressure vessel shall not be lower than the design pressure of equipment or vessel, and shall meet the following requirements:
- (1) The design pressure of the pipeline with safety relief device shall not be lower than the sum of safety relief pressure and static pressure of liquid column.
- (2) When there is no safety relief device, the design pressure shall not be lower than the sum of the maximum pressure and hydrostatic column pressure that the pressure source may reach.
2. The design pressure of outlet pipeline of centrifugal pump without safety relief device shall be the greater of the following two values
- (1) Normal suction pressure of centrifugal pump plus 1.2 times of rated differential pressure of pump.
- (2) Maximum suction pressure of centrifugal pump plus outlet pressure difference of pump.
3. The pressure of vacuum pipeline is 0.098mpa.
The design temperature of chemical pipeline and its components shall not be lower than the most stringent requirements of pressure and temperature during operation.
The design temperature of different pipelines is determined by the following requirements:
1. Design temperature of non insulated pipe
(1) For the pipe components of Sha grade, the medium temperature shall be taken as the design temperature. If other temperatures are taken as the design temperature, it must be calculated and verified through experiments.
(2) For the design temperature of other grades of pipes and their components, when the medium temperature is less than 65 ℃, the medium temperature shall be taken. When the medium temperature is greater than or equal to 65 ℃, the following principles shall be followed:
A. The design temperature of pipes, butt welded pipe fittings, valves and other components with wall thickness similar to that of pipes is not generally higher than 95% of the medium temperature.
B. Flange, gasket and flanged valve fittings shall not be lower than 90% medium temperature.
C. Bolts, nuts and other fasteners shall not be lower than 80% medium temperature.
2. The maximum and minimum operating temperature of the medium shall be taken as the design temperature for the pipeline with external insulation layer according to the severity of the effect of temperature conditions on the pipe.
3. The design temperature of the base material of the pipe with inner or inner thermal insulation layer shall be determined by heat generation calculation or actual measurement.
4. When the process temperature of the pipe with jacket will be higher than that of the heat tracing medium, the process medium temperature shall be taken as the design temperature; when the process medium temperature is lower than that of the heat tracing medium, the temperature of the heat tracing medium shall be reduced by 10 degrees and the temperature of the process medium shall be higher
5. For safety relief pipes, the maximum or minimum temperature that may occur during discharge shall be taken as the design temperature.
6. The pipeline requiring purging shall be determined according to specific conditions.
Factors to be considered in piping layout
Pipes with corrosive materials shall be arranged below or outside the parallel pipes. Pipelines with inflammable, explosive, toxic and corrosive materials shall not be laid in living areas, stairs and corridors, and shall be equipped with safety valves, anti riot films, flame arresters, water seals, etc. The waterproof, anti riot device and vent pipe shall be led to the outdoor designated place or more than 2m above the roof.
Cold and hot pipes shall be arranged separately as far as possible. When necessary, the heat pipe is on and the cold pipe is on. The distance between the outer surfaces of the thermal insulation layer is generally not less than 0.5m when the upper and lower surfaces are parallel. In case of cross arrangement, it shall not be less than 0.25m, and the thickness of insulation material and insulation layer shall be in accordance with the specification.
The pipeline shall be laid with a slope, which generally follows the direction of material flow, but also has the opposite direction of material flow. The gradient is generally 1 / 100-5 / 1000. For the material pipe with high viscosity, the gradient is required to be larger, up to 1 / 100. The slope of material pipeline containing solid crystal can reach about 5 / 100. When the production of buried pipelines and pipelines laid in trenches is stopped, the accumulated materials shall not be fully discharged, and the laying slope may not be considered.
The pipeline layout shall not only meet the requirements of normal production, but also meet the requirements of startup, shutdown and accident handling. During start-up and shutdown, due to the start-up and stop of relevant parts, bypass pipes shall be set, and start-up loading pipes, discharge pipes and reprocessing pipes for unqualified products shall be set. The pipes shall be able to adapt to operation changes, avoid tedious and waste.
A drain port with a steam trap and an expander shall be set at the proper place of the main steam pipe and the long-distance pipeline. For the sake of safety, try not to direct the high-pressure steam into the low-pressure steam system. If necessary, install a pressure reducing valve and a safety valve on the low-pressure system.
Sewage shall be discharged to special system and comprehensive utilization shall be considered. According to the specific situation of sewage, the combined type (i.e. industrial sewage, rainwater and defecation are all discharged from one pipe network) or separate type (i.e. industrial sewage and defecation are discharged from one pipe network, while rainwater and industrial clear water are discharged from another pipe network) can be used respectively. Toxic sewage can only be discharged after treatment.
The vacuum pipeline should be shortened as much as possible to avoid too many twists and turns, so that the resistance is small and the vacuum degree is greater. The stop valve should also be avoided because of its high resistance, which affects the vacuum degree of the system.
Construction, operation and maintenance
Pipes with many branch pipes shall be arranged outside the parallel pipes. When the branch pipe is led out, the gas pipe is led out from above, and the liquid pipe is led out from below. The pipelines shall be arranged in a centralized overhead way, and shall be straight and turn less as far as possible, without blocking doors and windows and hindering the maintenance of equipment, valves, pipe fittings, etc.; shall not hinder the crane operation; and shall not be installed in the 2.2m space on the ground of the walking corridor.
“Air pocket”, “pocket” and “cecum” shall be avoided in pipes. The gas gathering system shall be arranged so that the steam can be easily discharged to the highest point.
If possible, the pipe shall be installed along the wall, and the distance between the pipe and the wall shall be based on the principle of being able to accommodate pipe fittings, valves and convenient maintenance.
The valve shall be arranged at the place convenient for operation. Frequently operated valves shall be arranged in order of operation. The valves that are easy to open wrongly and may cause major accidents shall be separated from each other and painted with different colors.
If the underground pipeline passes through the road or load area, protective measures shall be taken.
The weight of pipes and valves shall not be considered to be supported on the equipment (especially manufacturing equipment, non-metallic material equipment, ferrosilicon pump, etc.)
For the two equipment rooms close to each other, the pipeline shall not be directly connected. As the gasket is not suitable for registration, it is difficult to connect closely. If one of the equipment is not fixed with the building or has waveform expansion, 45 is recommended. Miter or 90. Bend.
When the pipeline passes through the floor, roof or wall, a large diameter pipe sleeve shall be installed, and the pipe sleeve shall be 50mm higher than the floor and the platform surface.
Cables, lighting, instruments, heating and other pipes shall be taken into account in the pipeline layout, which shall be taken into full consideration and put in place.
Piping arrangement of unit equipment
1. What are the tower arrangements?
The specific requirements are tower layout:
In general, single row layout is adopted. When there are two or more towers or vertical vessels on one side of the pipe gallery, the center line is generally aligned. For example, when two or more towers are equipped with platform, the center line or tangent line should be aligned;
For the tower with smaller diameter and higher body, it can be arranged in two rows or in a triangle. In this way, the tower can be connected by platform to improve its stability. However, for the rooting components of the platform, sliding guide nodes should be used to adapt to the influence of different operating temperatures;
For frame type arrangement, the tower with diameter DN ≤ 1000mm can also be arranged in the frame or one side of the frame. Use the frame to improve its stability and set up platform and ladder. For the sectional tower arranged on the frame, when it is unable to use the mechanical hoisting equipment, the maintenance hoisting facilities shall be set on the frame.
2. What are the requirements for the arrangement of the tower and its associated equipment?
Layout requirements of tower and its associated equipment:
The tower and its associated equipment, such as feed heater, reboiler heated by non open fire, tower top condenser, reflux tank, tower bottom extraction pump, etc., should be arranged close to each other according to the process flow sequence. If necessary, an independent operating system can be formed and set in a zone, so as to facilitate operation and management.
3. How to determine the distance between the tower and vertical pipe rack along the pipe rack?
The distance between the tower and vertical vessel arranged along the pipe gallery and the pipe gallery shall be determined according to the following requirements:
When the pump is arranged between the tower and the pipe gallery, it shall be determined according to the operation, maintenance and piping requirements of the pump;
When no pump is arranged between the tower and the pipe gallery, the distance between the outer wall of the tower and the center line of the pipe rack column should not be less than 3m.
4. How to determine the distance between towers or between towers and other adjacent equipment?
The distance between tower and tower or between tower and other adjacent equipment shall not only meet the layout and installation requirements of pipeline, platform, instrument and small equipment, but also meet the requirements of operation, maintenance channel and foundation layout. The clear distance between two towers should not be less than 2.5m 。
5. What should be the installation height of tower and vertical vessel?
When using internal pressure or fluid gravity to send materials to other equipment or pipelines, the internal pressure and the pressure and height of the equipment or pipelines to be sent shall be determined;
When pumping, the installation height of the equipment shall be determined by the NPSH of the pump and the pressure drop of the suction pipe;
The installation height of the tower with non open fire heating heavy Buddha should be determined according to the mutual relationship between the tower and the reboiler required by the process and the operation requirements;
The minimum clearance required for the installation and operation of the tower bottom pipeline shall be met, and the foundation surface of the tower shall not be less than 200mm above the ground.
6. What are the general requirements for the arrangement of heat exchange equipment?
General requirements for arrangement of heat exchange equipment:
(1) Shell and tube heat exchanger associated with fractionator, such as reboiler at the bottom of tower, condenser at the top of tower, etc. The process flow should be arranged near the fractionator in sequence;
(2) The heat exchanger for heat exchange of two kinds of materials should be arranged in the nearest position of the pipeline connecting the inlet and outlet of two kinds of materials;
(3) The shell and tube heat exchanger with one material and several different materials shall be arranged in groups;
(4) Several groups of coolers for different materials shall be cooled with water or refrigerant, which shall be arranged in groups;
(5) For the heat exchange equipment arranged in groups, the center line of bearing foundation should be aligned. When the distance between supports is different, the center line of bearing foundation at one end should be aligned. For the convenience of pipe connection, the heat exchanger arranged on the ground can also be aligned with the center line of the inlet and outlet nozzles of the pipe side;
(6) The heat exchange equipment shall be arranged on the ground as much as possible, but the number of heat exchange equipment can be arranged on the framework:
When the floating head heat exchanger is arranged on the ground, the following requirements shall be met:
There should be an open space of no less than 0.6m wide on both sides of the floating head and the pipe box, and there should be an open space of no less than 1.2m wide in front of the floating head end;
A space at least 1.5m longer than the tube bundle length shall be left in front of the tube box from the end of the tube box.
When the floating head heat exchanger is arranged on the frame, the following requirements shall be met:
The platform clearance in front of the floating head end should not be less than 0.8m;
The clear space of the platform in front of the pipe box end shall not be less than 1MN, and the platform shall adopt the removable handrail, and the space required for the withdrawal area of the pipe bundle shall be considered;
The frame height shall be able to meet the lifting requirements of the header of the tube box and floating head of the heat exchanger.
(7) In order to save land occupation or facilitate process operation, two heat exchange equipment can be arranged together. However, for two-phase flow medium or heat exchanger with shell diameter greater than or equal to 1.2m, overlapping arrangement is not suitable;
(8) The clear distance between heat exchangers and between heat exchangers and other equipment shall not be less than 0.7m;
(9) The heat exchange equipment for heavy oil products or materials polluting the environment should not be arranged on the framework;
(10) If there is no floor or platform separation above the heat exchanger whose operating temperature is higher than the spontaneous ignition point of the material, no other equipment shall be arranged.
7. What are the general requirements for reboiler arrangement?
General requirements for arrangement of reboiler are as follows:
(l) The distance between the reboiler heated by open fire and the tower shall be arranged according to the distance between the furnace and the tower in the fire prevention code;
(2) The horizontal reboiler heated by steam or heat carrier shall be arranged close to the tower and maintain a certain height difference with the tower (determined by the process design). The distance between the two shall meet the requirements of pipeline layout. One end of the reboiler’s tube bundle shall be provided with maintenance site and access;
(3) The vertical reboiler should be arranged on the side of the tower with the tower as the support and maintain a certain height difference with the tower (determined by the process design). Enough maintenance space shall be reserved above it;
(4) When multiple parallel vertical reboilers are required for a tower, the position and installation height of the reboiler shall not only ensure the process requirements, but also meet the layout requirements of the inlet and outlet manifolds and facilitate operation and maintenance.
8. What are the general requirements for air cooler arrangement?
General requirements for arrangement of air cooler are as follows:
(l) The air cooler (hereinafter referred to as air cooler) should be arranged at the downwind side of the annual minimum frequency wind direction of the device;
(2) The air cooler shall be arranged above the main pipe gallery, on the top floor of the framework or on the top of the tower;
(3) The air cooler shall not be arranged above the point where the operating temperature is equal to or higher than the spontaneous combustion of materials and the equipment for transporting and storing liquefied hydrocarbon; otherwise, the partition of non combustible materials shall be used for isolation protection;
(4) When multiple groups of air coolers are arranged together, they should be arranged in the same way, and should be arranged in rows; one part of them should not be arranged in rows while the other part should be arranged in rows;
(5) Inclined roof air cooler should not face the main wind direction in summer. Inclined roof air coolers should be arranged in rows. If arranged in rows, there should be no less than 3m space between the two rows;
(6) The distance between the frame columns of two humidifying air coolers or combined dry and wet air coolers arranged side by side shall not be less than 3m;
(7) A platform shall be set at the pipe boxes at both ends of the air cooler tube bundle and the transmission machinery;
(8) Necessary maintenance site and access shall be reserved on the ground at one side of the framework or main pipe gallery of the air cooler.
9. How can the arrangement of air coolers avoid their own or mutual hot air circulation?
How can the arrangement of air coolers avoid their own or mutual hot air circulation?
(1) Air coolers of the same type are arranged at the same height;
(2) Adjacent air coolers are arranged closely;
(3) The group of dry-type air coolers and induced air coolers shall be arranged separately, and the induced air coolers shall be arranged at the downwind side of the annual minimum frequency wind direction of the air coolers;
(4) When the induced air cooler and the blower air cooler are arranged together, the tube bundle of the blower air cooler shall be raised.
10. What are the general requirements for furnace arrangement?
The general requirements for the layout of heating furnace are:
(1) The open fire heating furnace should be arranged at the edge well of the device close to the fire fighting channel, and at the downwind side of the annual minimum frequency wind direction of combustible gas, liquefied hydrocarbon, class A and B liquid equipment;
(2) The heating furnace and other open fire equipment shall be arranged together;
(3) Several heating furnaces can be arranged in rows according to the furnace center line. The net distance between two heating furnaces should not be less than 3m;
(4) When the heating furnace tube is hoisted by the motor-driven maintenance equipment, there shall be a passage and maintenance site for the motor-driven maintenance equipment. For the heating furnace with horizontal furnace tube, the length of the maintenance site shall not be less than the furnace tube length plus 2m on the side of the extraction furnace tube;
(5) The distance between the outer wall of heating furnace and the edge of maintenance road shall not be less than 3m;
(6) For the heating furnace with steam generator, the steam drum should be set on the top of the heating furnace or the adjacent frame;
(7) The distance between the heating furnace and its auxiliary fuel gas separating tank and fuel gas heater shall not be less than 6m;
(8) When the heating furnace has air preheater, blower, induced draft fan and other auxiliary equipment, the layout of the auxiliary equipment shall not hinder the maintenance of itself and the heating furnace;
(9) The fire separation distance between the heating furnace and the liquefied hydrocarbon equipment arranged in the open air shall not be less than 22.5m. When the solid wall of non combustible materials is set between the equipment, the separation distance can be reduced, but not less than 15m. The height of the solid wall shall not be less than 3m, the distance from the heating furnace shall not be more than 5m, and the combustible gas shall be prevented from entering the furnace body;
When the workshop of liquefied hydrocarbon equipment or class a gas compressor room faces the heating furnace with a closed wall, the distance between the heating furnace and the workshop can be reduced, but not less than 15m.
11. What are the requirements of vertical vessel arrangement?
The shape of vertical vessel is similar to that of tower, but the internal structure is not as complicated as that of tower. The layout and installation height of vertical vessel can refer to the layout requirements of tower. In addition, the following requirements shall be considered:
(1) For the convenience of operation, the vertical vessel can be installed on the ground, floor or platform, or it can pass through the floor or platform, and it can be supported on the floor or platform with lugs;
(2) When the vertical vessel passes through the floor or platform for installation, the liquid level indication and control instrument on the vessel shall be avoided to pass through the floor or platform as far as possible;
(3) In order to prevent the solidification of viscous materials or the settlement of solid materials, the supporting structure should be set from the ground as far as possible when the vertical container is equipped with a large load agitator;
(4) For vertical vessels with top opening, when manual feeding is required, the height of the feeding point should not be higher than the floor or platform by 1 m. if it is higher than 1 m, the feeding platform or steps should be considered.
12. What are the requirements for layout and installation height of horizontal vessels?
The layout and installation height of horizontal vessels have these requirements:
(l) Horizontal vessels should be arranged in groups. Horizontal vessels arranged in groups should be aligned according to the center line of bearing foundation or tangent line of head. The clearance between horizontal vessels can be considered as 0.7m.
(2) When determining the size of horizontal vessels in process design, vessels of the same length and different diameters shall be selected as far as possible to facilitate the arrangement of equipment.
(3) When determining the installation height of horizontal vessel, in addition to the requirements of material gravity flow or pump suction height, the following requirements shall also be met:
When there is a liquid collecting bag under the container, there should be enough space for the operation of the liquid collecting bag and the detection instrument;
When an operation channel is required under the vessel, the clearance between the piping at the bottom of the vessel and the ground shall not be less than 2.2m;
When horizontal vessels of different diameters are arranged in groups on the ground or on the same floor or platform, the elevation of the center line of horizontal vessels with smaller diameter can be increased appropriately to make it consistent with the elevation of the item surface of horizontal vessels with larger diameter, so as to facilitate the setting of joint platform.
(4) When horizontal vessels are arranged in the pit, the accumulated water and toxic, combustible and explosive media in the pit shall be properly handled. The size of the pit shall meet the operation and maintenance requirements of the vessel. For rainy areas, canopy can be set on the top of the pit.
(5) The setting of the platform of horizontal vessel shall consider the operation of manhole and liquid level meter. The top platform elevation should be 150 mm lower than the top nozzle flange surface. When the height of the upper interface of the liquid level gauge is more than 3m from the ground or the operation platform, the liquid level gauge shall be installed near the vertical ladder. For horizontal vessels arranged in a centralized way, a combined platform can be provided.
13. What are the pump arrangements?
There are three types of pump layout: outdoor layout, semi outdoor layout and indoor layout.
(1) Pumps arranged in the open air are usually arranged at the lower side of the pipe gallery or near the suction equipment. The utility model has the advantages of good ventilation, convenient operation and maintenance;
(2) Pumps arranged in the semi open air and semi open air are suitable for rainy areas. Generally, pumps are arranged under the pipe gallery and a canopy is arranged above the pipes. Or the pump shall be arranged on the lower floor of the frame, with the frame platform as the canopy. These pumps can be arranged in single row, double row or multi row according to the design layout requirements related to pumps;
(3) Indoor arrangement in cold or windy sand area can be arranged in the indoor pump. If the process requires the equipment to be arranged indoors, the pumps to which it belongs shall also be arranged indoors.
14. What are the specific requirements for pump layout?
The specific requirements for pump layout are as follows:
(1) The pumps arranged in rows shall be arranged in groups according to the fire protection requirements, operation conditions and material characteristics; when the pumps are arranged in open air and semi open air, the combustible liquid pumps with the operating temperature equal to or higher than the self ignition point shall be arranged in a centralized way; the fire separation distance between the pumps and the combustible liquid pumps with the operating temperature lower than the self ignition point shall be no less than 4.5m; the fire separation distance between the pumps and the liquid hydrocarbon pumps shall be no less than 7.5m;
(2) When the pumps are arranged in rows, the pump end should be discharged. Align the population center line or the foundation sideline at the pump end;
(3) When the pumps are arranged in two rows, the power ends of the two rows of pumps should be opposite, and maintenance channels should be reserved in the middle;
(4) When the pump is arranged under or outside the main pipe gallery, the minimum clear width and height of the channel in the pump area shall be 2M and 3M respectively. The width of the operation channel in front of the pump end shall not be less than 1m;
(5) When the pump is arranged under or outside the pipe gallery, whether single row or double row, the center line of the pump and the driving machine should be perpendicular to the direction of the pipe gallery;
(6) When the pump is arranged indoors, the clear distance between two rows of pumps shall not be less than 2m. The clear distance between the pump end or pump side and the wall shall meet the operation and maintenance requirements and shall not be less than LM;
(7) In addition to the small pump installed on the combined foundation, the clear distance between the two pumps should not be less than 0.7m;
(8) The foundation surface of the pump should be 200 mm higher than the ground. The minimum shall not be less than 100mm; when installing the filter in front of the pump suction, the pump foundation height shall consider that the filter can be easily cleaned and disassembled;
(9) When the vertical pump is arranged under the main pipe gallery or under the framework, the space required for the installation and maintenance of the pump body shall be reserved above it;
(10) Transport of extremely hazardous substances (e.g. propylene? The pump room of hydrocyanic acid, etc.) shall be separated from other pump rooms;
(11) The fire pump house shall be equipped with double power sources;
(12) The public standby pump should be arranged in the middle of the corresponding pump;
(13) The layout of the pump shall consider the requirements of the flexible design of the pipeline.
15. What are the general requirements for compressor arrangement?
The general requirements for compressor arrangement are:
(1) The arrangement of compressor unit and its auxiliary equipment shall meet the requirements of the manufacturer;
(2) The compressor should be arranged near the equipment being sucked, and its auxiliary equipment should be arranged near the unit;
(3) The layout of combustible gas compressor shall meet the following requirements:
The distance between the open fire equipment and non explosion-proof electrical equipment shall comply with the provisions of the current national standard code for design of electrical installations in explosive and fire hazardous environments (GB 50028) and code for design and fire protection of petrochemical enterprises (GB 50160);
It should be arranged in open air or semi open. In cold or windy areas, it can be arranged in the workshop;
Class a gas compressor plant with single driving power equal to or greater than 150KW shall not share a building with other class A, B and C rooms; class A, B and C liquid equipment shall not be arranged above the compressor, but the self used high-level lubricating oil tank shall not be subject to this limit.
(4) For compressors arranged in single layer, when the foundation is high, the operation platform should be set as required; when there are many auxiliary equipment, the compressor should be arranged in two layers.
16. What should be the installation height of the compressor?
The installation height of the compressor shall be determined according to its structural characteristics. The installation height of compressor with inlet and outlet at the bottom shall meet the following requirements:
(1) Clearance requirements between the inlet and outlet connecting pipes and the ground;
(2) Requirements for connection height of inlet and outlet connecting pipes and pipes on pipe gallery;
(3) Requirements for installation height and size of filter on suction pipe;
(4) In order to reduce the vibration, the installation height of reciprocating compressor should be reduced.
17. What fire protection regulations should the layout of control room, power transformation and distribution room and Laboratory of the device comply with?
What fire protection regulations should the layout of control room, power transformation and distribution room and Laboratory of the device comply with?
(1) The control room and power transformation and distribution room should be set on the ground floor of the building. If it is necessary for production or restricted by other conditions, the control room and power transformation and distribution room can be set on the second floor or higher;
(2) The indoor floor of control room, power transformation and distribution room and laboratory shall be at least 0.6m higher than the outdoor floor in the device that may emit combustible gas heavier than air;
(3) The external wall of the control room towards the equipment side with fire risk shall be the solid wall of non combustible materials without doors, windows and openings;
(4) In the control room or laboratory, it is not allowed to install the on-line primary analysis instrument of combustible gas, liquefied hydrocarbon and combustible liquid. When the above instruments are installed in the adjacent rooms of control room and laboratory, the middle partition wall shall be firewall.
18. What requirements should be met for channel setting of production unit? What is the minimum width and minimum clear height of the channel in the device?
When arranging the equipment, necessary passageways and sites shall be set according to the needs of construction, maintenance, operation and fire control. Inside the device, the device shall be divided into equipment and building areas with an area of no more than 10000m2 by road. When the area of esterification polymerization, tapping and post-processing workshop of synthetic fiber plant is larger than 10000m2, channels shall be set on both sides. The main vehicle passage in the device shall be connected with the factory road.
(1) The installation of fire fighting access shall meet the following requirements:
When the width of the device is more than 60m, a through fire channel shall be set in the device;
When the width of the device is less than or equal to 60m, and there are fire passages on both sides of the device, the through fire passage may not be set. Incoherent roads within the plant shall be provided with a return yard.
The width of the road shall not be less than 4m, the clear distance between the pipe rack on the road shoulder and the edge of the road surface shall not be less than LM, the turning radius of the inner line of the road surface shall not be less than 7m, and the clear height of the road surface shall not be less than 4.5m.
(2) The maintenance channel shall meet the requirements of motor maintenance machines and tools for road width, turning radius and bearing load, and can lead to the hoisting hole for equipment maintenance.
(3) The main vehicle passage, fire fighting passage and maintenance passage in the device shall be set together.
(4) The operation channel shall be determined according to the frequency of production operation, patrol inspection, small maintenance and the distribution of operation points.
19. How to consider in the design of pipeline layout along the tower?
The following five points shall be considered in the design of pipeline layout along the tower:
(1) It shall meet the requirements of process pipe and instrument flow chart;
(2) The pipeline layout shall be planned from the top of the tower to the bottom of the tower from top to bottom, and the location of the tower top pipeline and large diameter pipeline and the direction of the free flow pipeline shall be considered first, then the pressure pipeline and general pipeline shall be arranged, and finally the tower bottom pipeline and small diameter pipeline shall be considered;
(3) It should be convenient to operate, maintain, safe and reliable, economical and reasonable;
(4) Each pipeline shall be as short as possible according to its start and end points, but it must meet the requirements of pipeline flexibility;
(5) Each pipeline shall be arranged along the tower as far as possible, and pay attention to a “good appearance”:
There are two situations to consider: one is that each pipeline is arranged separately; the other is that it is arranged in groups according to the pipeline (if the concentrated load of the pipeline is large in this way, the consent of the equipment designer shall be obtained);
On the pipeline side, it is arranged in concentric circle along the outer wall of the tower, or in tangent line along the outer wall of the tower.
20. What are the key points of tower top piping design?
The key points of tower top pipeline design are as follows:
- (1) The overhead pipelines generally include overhead oil and gas, vent and safety valve outlet pipelines. The vent pipe on the top of the tower is generally installed on the top of the horizontal pipe section at the highest point of the oil and gas pipeline on the top of the tower, and shall meet the requirements of the fire prevention code;
- (2) The medium in the oil and gas pipeline on the top of the tower is generally gas phase, the pipe diameter is large, the pipeline is as short as possible, the “step-by-step is low”, the bagged pipe is not suitable, and has certain flexibility;
- (3) For each pipeline along the tower, load-bearing support shall be set at the upper part and guide support shall be set at appropriate position to avoid excessive stress on the nozzle;
- (4) The oil and gas pipeline on the top of fractionator is generally not insulated and only hot resistant; if the pipeline has more than one cold exchange equipment, it should be arranged symmetrically to avoid bias current;
- (5) In case of two-stage condensation at the top of the tower, the pipeline arrangement shall make the condensate flow automatically step by step, and the main oil and gas pipe and the branch pipe at the inlet of the condensation road shall be arranged symmetrically to make the flow uniform;
- (6) When the tower top pressure is controlled by the thermal bypass, the thermal pipeline shall be insulated as short as possible, its regulating valve shall be installed on the upper part of the reflux tank, and the pipeline shall not appear “bag shape” to avoid liquid accumulation;
- (7) The oil and gas pipeline on the top of the pressure reducing tower is directly welded with the opening of the tower without flange connection, so as to reduce the leakage.
Pipe layout laid on pipe gallery
The types of pipes laid on the pipe gallery are: utility pipes, utility pipes, instrument pipes and cables.
- (1) The general layout of the equipment is arranged on both sides of the pipe gallery according to the process flow sequence, so the pipeline connected with the equipment on the left side of the pipe gallery is arranged on the left side of the pipe gallery and the pipeline connected with the equipment on the right side is arranged on the right side of the pipe gallery. Utility pipes should be arranged in the middle of the pipe gallery.
- (2) Heavy pipes for large-diameter liquid transportation shall be arranged close to or above the column of pipe rack to make the beam of pipe rack bear small bending moment. Small diameter light pipes should be arranged in the center of the pipe rack.
- (3) For double-layer pipe gallery, gas pipes and hot pipes should be arranged on the upper layer, while liquid pipes, cold flow pipes and other pipes with corrosive medium should be arranged on the lower layer. Therefore, the steam, compressed air, gas and other process gas pipelines in the utility pipeline are arranged on the upper layer, and the layout of other utility pipelines can be determined according to the situation.
- (4) Steam, heat carrier oil and other utility pipelines with shut-off valve are set at the root of branch pipe, and the position shall be convenient for setting valve operation platform.
- (5) Low temperature freezing pipeline, liquefied petroleum gas pipeline and other pipelines that should avoid heating should not be arranged above the thermal pipeline or close to the uninsulated thermal pipeline.
- (6) When it is difficult to change the elevation of individual large-diameter pipe into the pipe gallery, it can be entered by turning flat. At this time, the pipe shall be arranged at the edge of the pipe gallery.
- (7) There are usually many valves in the pipe gallery at the entrance and exit of the device, so an operation platform should be set, and the platform should be located above the pipeline. If necessary, operation and maintenance access shall be set along the pipe gallery direction.
- (8) Along the outside of the columns on both sides of the pipe gallery, small equipment such as regulating valve group, tracing steam distribution station, condensate collection station, sampling cooler, filter, etc. are usually arranged.
- (9) When arranging the pipeline of the pipe gallery, the position for the instrument rack shall be reserved in consultation with the instrument specialty. When the cable tray in the device is laid overhead, it is also necessary to consult with the electrical discipline and reserve a good position for the cable tray.
The layout of pipes on the pipe gallery shall be determined according to the following factors:
- Factors of pipe diameter: heavy pipes (whether process pipes or utility pipes) for large-diameter liquid transportation shall be arranged close to the pipe rack column or above the pipe rack column, so as to make the beam of pipe rack bear small bending moment, especially when it is difficult for individual large-diameter pipes to enter into the pipe rack to change elevation, the pipe shall be arranged in the pipe rack The edge of the gallery. Small diameter light pipes should be arranged in the center of the pipe rack. Because the span of small-diameter pipe is often smaller than that of pipe support, the location of these small pipes should also consider using large pipes to set up intermediate supports. For single column pipe support, the load on both sides of the pipe support column shall be uniform as far as possible.
- Factors of equipment location: the more economical and reasonable equipment layout is to arrange the equipment on both sides of the pipe gallery according to the process flow sequence, so it is natural that the pipeline connected with the equipment on the left side of the pipe gallery is arranged on the left side of the pipe gallery and the pipeline connected with the equipment on the right side is arranged on the right side of the pipe gallery. The utility pipeline should be arranged in the middle of the pipe gallery, which is easy to be led out to both sides.
- Factors for the nature of materials: low temperature pipelines and materials pipelines that are not suitable for heating, such as liquefied hydrocarbon pipelines and refrigeration pipelines, shall not be arranged close to steam pipelines or thermal pipelines that are not insulated; oxygen pipelines shall not be arranged adjacent to combustible gas and liquid pipelines; corrosive medium pipelines shall be arranged at the lower layer but not directly above the driving equipment. For the double-layer pipe gallery, the general principle is that the utility pipeline is arranged on the upper layer and the process pipeline is arranged on the lower layer. Generally, gas pipes, hot pipes and process pipes with long laying distance should be arranged on the upper layer; liquid, cold, liquefied petroleum gas, chemical agents and other corrosive medium pipes should be arranged on the lower layer. Therefore, the steam, compressed air, nitrogen, oxygen, fuel gas and flare lines in the utility pipeline, the pipelines related to the top equipment of the pipe bridge and other process gas pipelines are arranged on the upper layer; the fresh water, circulating water and other liquid utility pipelines are arranged on the lower or upper layer; the process pipeline shall be arranged on the upper or lower layer according to the elevation of the equipment nozzles connected on both sides, so as to The pipeline “step high” or “step low”, when there is no regulating valve in the lower position, the pipeline shall not be bagged.
- Factors of thermal stress: multiple pipes that need to absorb thermal expansion with π type compensator should be arranged in groups horizontally. If the pipe diameter is large and the temperature is high, the pipeline that needs larger π type compensator should be placed on the outside. Otherwise, the pipeline that needs larger π type compensator should be placed on the inside in order to set up π type compensator in groups. When the width of the pipe gallery is large, the position of these pipes to be compensated shall be appropriate to avoid the excessive length of the arm extended by the elbow. Because the elbow arm is usually supported on the side beam of the pipe gallery.
Other piping arrangements
(1) Vent valve shall be set at the highest point of the pipeline, and vent valve shall be set at the lowest point. Vent valve close to main equipment shall be directly connected with equipment body.
(2) Flame arrester shall be set on the pipeline for discharging inflammable and explosive gas, and the flame arrester on the exhaust pipeline of outdoor container shall be placed at 500mm of the exhaust pipe interface (the interface with the equipment). The exhaust of indoor container must be connected to the roof, and the flame arrester shall be placed on or near the roof, and the distance between the flame arrester and the discharge outlet shall not exceed 1m.
(3) When the sampling point is set on the pipeline, the position that is convenient for operation and representative and authentic for taking out the sample shall be selected.
Source: China Chemical Pipeline Manufacturer – Yaang Pipe Industry Co., Limited (www.steeljrv.com)
(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)
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