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The Process Pipe Design of the Petrochemical Plant

Posted: 02/15/2022 16:21:11 Hits: 5

The petrochemical industry is comprehensive. The petrochemical industry is inseparable from the use of chemical equipment. Process pipeline design is a very important part in the petrochemical industry. The rational design is related to the quality of the installation of pipelines. From the design of process pipelines of petrochemical plants in China, there are many problems that need to be solved. The pipeline's process design involves a lot of content and requires professionalism. Any error in any link may affect the production of the entire petrochemical industry. In the specific petrochemical production process, we should pay attention to practical efficiency, apply modern production equipment, further improve the production efficiency of the petrochemical industry, ensure production quality and reduce production costs. The petrochemical industry has different requirements for the selection of chemical equipment. The chemical equipment should have stable operating performance. Improve the design of the process pipeline, and ensure the safety of oil products to the greatest extent.

The process pipe design of petrochemical plant involves a lot of content and is more professional. We mainly summarize from four aspects in this article: classifications of pipeline materials, pipeline design of towers, pumps and cold exchange equipment. There are certain differences in the classification of pipeline materials. There is a certain temperature difference between the high-pressure system and the low-pressure system of the chemical plant. When the two systems establish a connection, this temperature difference will affect the stability of the system connection. In order to eliminate this kind of influence, we need to reasonably divide the critical value according to the low-pressure pipeline level. Under normal circumstances, the critical value will be clearly divided in the pipeline design, but there are exceptions. At this time, we need to reasonably regulate and divide the correct demarcation point and demarcation line according to the specific situation.

The pipeline design of the tower is a comprehensive process, which includes many contents. The pipeline layout of the fractionating tower and the stripping tower is part of the content. The pipelines of the tower and container are interactive. In the design process, we should reasonably plan based on the pipeline properties and medium form. When the pipeline is set, the pipeline between the fractionating tower and the stripping should be treated separately, and a regulating valve group should be arranged in the middle layer of the stripping tower and the fractionating tower. The function of the regulating valve group is to control the pressure changes of the fractionating tower and the stripping tower, so that the pressure changes of the fractionating tower and the stripping tower are kept in a relatively stable state. The pressure at the top of the fractionating tower can be regulated by the thermal bypass. The thermal bypass has a certain temperature control function. The thermal bypass is kept as short as possible to avoid the generation of bag-shaped liquid accumulation. Change the regulating valve at the upper end of the return tank, so that the cooler is below the height of the return tank.

The pipeline design of the pump should take into account various influencing factors. When the eccentric reducer at the pump inlet is used, the suction pipeline of the pump should be reasonably planned. The diameter of the pump inlet's pipeline system shows a dynamic trend. Before installing the reducer at the pump inlet, the gas should be diluted so that the gas cannot gather at the reducer and avoid cavitation caused by improper installation. There are many types of horizontal inlet pipe fittings for the pump. In most cases, we choose the eccentric reducer. There are many types of horizontal inlet pipe fittings for the pump. In most cases, we choose the eccentric reducer. In the installation process of the eccentric reducer, we can install a drain valve at a lower position. The liquid has fluidity. When the liquid enters the pump nozzle, some problems will occur, such as bias flow and rotating eddy current, which will destroy the flow balance of the rotation of the impeller inside the pump nozzle, making the pump unable to operate normally. In severe cases, there will be air resistance, reducing the operation of the pump and shortening the service life of the pump. The pipeline design should take into account the planning of the straight pipe section at the pump inlet, and reduce the influence of external factors on the pump by adding straight pipe sections. The external form of the pump is diverse, and different pumps have different requirements for the straight pipe section. For example, for the side suction pump, the length of the straight pipe section in front of the suction port should be longer than the straight pipe section with three times the pipe diameter. For double suction centrifugal pumps, their double suction ports maintain a symmetrical state to prevent cavitation caused by two-way suction. If the pipeline of the suction port and the pump shaft are parallel, a straight pipe section of seven times the pipe diameter should be set up in front of the suction port of the pump. Conversely, when the suction pipe and pump shaft are in a vertical state, both the elbow and the valve can be used as straight pipe sections. The overall stability of the pump is relatively good. It belongs to a rotary machine. Under the action of external pressure, a certain movement trajectory will be formed. For example, when the nozzle is boosted by the pipeline, the original running trajectory of the rotating shaft will change, which forms a certain deviation. This deviation does not meet the standards of pipeline design, so this problem should be taken into account when designing the pipeline. Appropriate measures should be taken to strictly control the force of the pump nozzle, so that the force coefficient is controlled within a range. Predict the direction of the pipeline, arrange the pipeline reasonably according to the prediction results. Improve the flexibility of the pipeline; plan the load-bearing support and hanger, and then arrange the guide bracket under the load-bearing support and hanger, which can reduce the stress and moment of force of the pipeline acting on the pump nozzle.

The most ideal state of pipeline design is the shortest length and the lowest pressure loss. Of course, this is relative. In the pipeline transporting heat medium, there will be thermal stress analysis. Under the influence of thermal stress, the number of pipeline elbows will increase, and the direction of the pipeline change, which is not conducive to the stability of the pipeline's operation and increases the cost of capital investment. In order to make the pump run normally at a high temperature, we need to reasonably deploy the pipeline, conduct a comprehensive analysis according to the pipeline's direction and operating conditions, preset the load-bearing bracket, improve the pipeline's operation efficiency and reduce the cost budget.

Compared with other process design, the pipeline design of cold exchange equipment is relatively simple. The pipeline design must meet the PID standard, and the flexibility and economy of pipelines should be considered comprehensively. When choosing alloy steel and stainless steel pipelines, give priority to short pipelines and fewer elbows. It is necessary to focus on the maintenance of the cold exchange equipment and the thermal stress of the pipeline. The shell type heat exchange has two types: centralized arrangement and separate arrangement. The pipeline arrangement should not hinder the dismantling space of the tube box and the flat welding side of the smooth surface. There is a certain connection among the valve, the regulating valve group and the operating channel of the heat exchanger, and the regulating valve group and the channel are kept in a parallel state. The thermometers around the heat exchanger pipeline should be arranged in the channel, which is conducive to the observation of the staff, and the flange and the cylinder can be replaced at a close distance. Under normal circumstances, the heat exchanger is fixed at the port of the tube box, so we need to consider the displacement of the port due to thermal stress. When designing the pipeline, the performance of the pipeline should be optimized reasonably, and the port of the tube box should not be subjected to excessive heat. When a high temperature occurs for the pipeline, we must ensure that the shape of the pipeline has a certain thermal compensation ability, arrange the guide bracket, and differentiate the force on the nozzle.

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