Abstract: common design points in chemical process design are introduced, including the design of reducers, elbows, valves, and connections. The protective pipe of steam pipelines of chemical process units was designed and studied. The steam pipeline was arranged and drainage facilities were proposed. The design of steam branch pipes and steam condensate pipes provides a certain reference for the design of chemical process equipment.
One of the necessary items in the petrochemical production process is the design of protective pipes of steam pipes, which has an important impact on the operational safety and quality improvement of chemical plants. It is required to adopt unified planning and layout to design the relevant values and items in the steam pipeline system; make adjustments based on the actual situation in the actual steam pipeline's transportation, and select the corresponding conveying pressure and pipe diameters in combination with the design process of steam pipes' protective pipes. Make the protective pipe's design and process equipment fully unified.
1.
Common design points in chemical process design
1.1
The design of reducers
The reducer has an important influence on the protective pipe's design, and its design is required to be optimized. The concentric reducer and eccentric reducer are common reducers. In the process of selecting the
reducer, it is required to combine the actual protective piping requirements for the unit's steam design to choose the best form. You can design and select the corresponding protective piping design data on the pipe gallery. Flat-bottomed eccentric reducers are more common in design. If concentric reducers are used, they will increase the difficulty of the later stage of the construction, and the pipeline system on the steam pipe gallery is likely to be unstable during use.
1.2
The design of elbows
The important link of the protective pipe connection is the elbow, which is prone to some problems in the design process, such as the failure of the protective pipe's connection. Therefore, it is required to actively take a variety of effective measures in the process of the protective pipe's connection. Improve the drawing in combination with the actual situation or add elbows to effectively connect the protective pipe. However, in the specific design process, simply adding
elbows and the design being not good easily occur, and this will lead to greater running resistance during the operation of the elbow, which may cause welding seams or leakages and certain risks.
1.3
The design of valves
One of the important links in the protective pipe's design is the valve's design. Different valves have great differences based on uses. In order to ensure safety during use, it is required to select the most suitable valve. In the case of conveying different media, the corresponding operation mode and pipe grade should be selected.
2.
Research on the design of protective pipes of steam pipelines for chemical process equipment
2.1
Fixing the steam pipeline up
Because of the influence of factors such as external temperature, internal pressure in the pipe and steam temperature, a large amount of thermal expansion may occur inside the steam pipeline in operation. However, thermal expansion is difficult to be fully released in the pipeline in operation, it may affect the bracket, pipe and related pipe devices to a large extent. In the design process of traditional steam pipelines, bellows and natural compensation are generally used to prevent pressure absorption to deal with expansion caused by heat and contraction caused by cold that occur when the pipeline is in operation. The following design method of the 1000kt/a ethylene device is mainly adopted, and the relevant layout of the steam pipeline is shown in Table 1.
Table 1 Relevant layouts of steam pipelines in chemical process units