Design of steam pipeline (steel pipe)
Design of steam pipeline (steel pipe)
The steam pipes in the chemical plant are designed in this way.
When designing steam pipes in chemical plants, in order to ensure the quality and efficiency of the design, the pipe diameter should be selected reasonably, and the pipe layout should also meet the stress requirements. In addition, attention should be paid to other details to avoid water The phenomenon of hammering. Keywords: steel pipe, pipeline, steel pipe engineering, pipeline engineering, steel pipe engineering drawing, pipeline engineering drawing, steam pipeline, steam steel pipe.
1 Design of steam pipeline
Many different pipelines are installed in the chemical plant, generally arranged outside the plant or along the plant, supported in the air with brackets, and become pipe corridors. The configuration of the pipe gallery has specific requirements. Generally, process material pipes are arranged on the first and first floor pipe gallery, utility pipes are arranged on the third floor, and the instrument cable trough board is arranged on the fourth floor. The steam pipeline is arranged on the third floor.
In order to facilitate the installation of the π-shaped compensator, generally the steam pipe should be arranged on the side of the pipe gallery. In the case of high temperature, the steam pipe will expand. At this time, the π-shaped compensator can be used to absorb the thermal expansion of the pipe. Because the bellows expansion joint is more expensive and has a short service life, it is generally not used for absorption when the steam pipeline expands. When determining the installation location of the compensator, the pipeline must first be strictly analyzed so that the compensator can be centrally set. Generally, those pipes with relatively high temperature and large compensation are installed on the outside, while those on the inside are corresponding pipes with relatively low temperature and relatively small compensation. The π-shaped compensator is generally set in the middle position. In addition, the guide frame should be set on both sides of the compensator. The distance between the guide frame and the compensator is determined according to the stress of the pipeline. When calculating the thrust of the support and the stress of the steam pipe, the stress of the entire steam pipe should be calculated. Generally, multi-layer pipe corridors are installed in chemical plants, and steam pipes are installed on the upper layer of the multi-layer pipe corridors, so that the low-temperature pipeline and the liquid hydrocarbon pipeline are not adjacent. On the same layer, steam pipes and electronic instrument cables can be arranged at the same time, but the distance between the two should not be less than 200mm. The steam pipe can also be arranged on the lower layer of the electronic instrument cable, but the interval cannot be less than 500mm.
2 Design of steam pipeline drainage facilities
Under normal circumstances, the special drain is set in the steam pipe in the heating stage. Because a large amount of condensate is generated when driving, special drainage facilities should also be set up. The setting of drainage facilities should be selected according to the level of steam pressure.
Under normal circumstances, the ultra-high pressure pipeline does not produce condensate, and there is no corresponding specification of condensate pipeline installed on the ultra-high pressure steam official road, so generally there is no drainage facility on the ultra-high pressure official road. The ultra-high pressure pipeline has the characteristics of thick pipe wall, not easy to open holes, and high pressure, so it is generally not equipped with a liquid distribution bag. Under normal circumstances, general condensate will not be generated in high-pressure, medium-pressure and low-pressure pipelines, but in order to prevent a large amount of condensate from the steam pipeline during the heating phase or the start-up phase, a drain valve, Drainage facilities such as liquid distribution bags are on these steam pipes.
When setting up the steam pipeline drainage facility, the liquid distribution bag should be installed at the end of the steam main pipe. The interval between the liquid distribution bag on the steam main pipe is also specified. If it is in a saturated state, the distribution package in the device The liquid pack interval is 80mm. If it is overheated, the interval between the dispensing packs should be 160mm. If it is in a downhill state, the interval between the dispensing packs outside the device should be 300mkm, and if it is on a reverse slope, the interval between the dispensing packs outside the device should be 200mm. The steam trap is generally set when the saturated steam main pipe enters the device, and should be set near the boundary of the device. In addition, it is necessary to set a regular drainage measure in the lower part of the water separator. If the superheated steam main pipe enters the device, there is no need to install a water separator. The steam vent pipe should be directly discharged to the atmosphere. Therefore, a drain hole should be opened at the lower end of the steam vent pipe, and a DN15 pipe should be connected to a suitable place such as a drain or a funnel. A guide and load-bearing support should also be provided on the steam vent pipe. Because the flood pipeline is often discharged or connected to discharge, it should be led to the main operation area or a place where there are not too many operators.
3 Design of steam branch pipe
The top of the steam main pipe is provided with a steam branch pipe. Generally, a shut-off valve is installed on the steam branch pipe. In order to avoid liquid storage, the shut-off valve should be installed on the horizontal pipe, close to the main pipe. Some steam pipes have stricter requirements for using steam, so you cannot connect steam branch pipes to such steam pipes, and branch pipes cannot be connected from the π-shaped compensator of the steam pipe. If the branch pipe is connected to the main pipe at both ends of the π-shaped compensator, the branch pipe should not be affected by the displacement of the steam main pipe. During thermal expansion, the steam main pipe will produce a displacement of the branch pipe outlet point, and the branch pipe will not bear excessive pressure or displacement. Under normal circumstances, when the branch pipe is connected to the steam main pipe, the second valve group is used (the public number pipeline circle). However, in order to make the leakage can be found at any time, the second valve group cannot be used in the steam branch pipe or steam The main pipe is led out to connect to other process pipelines, but a three-valve group should be provided. According to different situations, the drainage settings, such as drain valves or traps, should be set at the low point of the steam branch pipe. When drainage facilities are installed on the official road, it should be based on different levels of pressure on the pipe gallery.
4 Design of steam condensate pipeline
Generally, steam pipes and steam condensate pipes are arranged on the same layer on the pipe gallery. In order to prevent water hammer, a π-shaped compensator can be installed on the steam condensate pipe. The π-line compensator should be set in a horizontal direction, or the riser should be designed as an inclined section.
Condensate comes out of steam traps with different pressures and should be connected to their respective recovery headers. When the nominal diameter of the branch pipe is not less than 50mm, it can be directly connected to the top of the steam condensate recovery main pipe. The printing plate uses flange connection as the trap to be set in the steam condensate recovery system, and there should not be a bag on the pipe at the inlet of the trap. If the trap is lower than the steam condensate recovery header, a check valve should also be installed behind the trap. When setting the check valve, it should be installed on the horizontal pipe, close to the steam condensate main pipe. The check valve should also be flanged to facilitate the removal of the check valve by the steam pipeline.
5 Points to note when designing steam pipes
① Choose pipe diameter reasonably
When choosing the pipe diameter, it should be based on the steam demand. When the pipe diameter is too large, it will increase investment, increase heat loss, and increase condensate. When the pipe diameter is too small, the pressure at the point of use of the steam will be caused, the steam flow will be insufficient, and finally water hammer and erosion will occur. Therefore, when selecting the pipe diameter, it cannot be too large or too small.
② Stress requirements
When arranging the pipeline, it must meet the stress requirements and strictly calculate the stress. The setting of the π-shaped compensator on the pipeline, the thrust of the fixed point of the compensator, and the setting of the piping of the steam pipe connected to the equipment must meet the stress requirements, so that the efficiency of the design work can be improved.
③Avoid water hammer
When the high-speed flowing water pill hits the installation parts, equipment or valves of the pipeline, it will produce certain vibration and noise, which is the so-called water hammer phenomenon. In order to avoid the phenomenon of water hammer, pay attention to the setting of the drainage system. In addition, when connecting the branch pipe to fetch steam, it should be above the main pipe. The pipeline cannot use too many branches, necking bends, etc. In order to prevent local sinking of the pipeline, the pipeline support must be set reasonably. The filter screen should be installed horizontally. Attention should be paid to these details, so as to avoid the phenomenon of water hammer and improve the quality and efficiency of steam pipeline design in chemical plants.
Sum up
There are many strict requirements for the installation of steam pipes in chemical plants. In addition, many details must be paid attention to. Only in this way can the design be scientific and reasonable, the efficiency of the steam pipes can be improved, and the steam pipes can function normally.
