The heat tracing design of pipeline plays an important role in real life. In the design, scientific and technical personnel need to determine the heat tracing coefficient and design quota based on the actual situation, so as to ensure that the heat tracing pipeline design meets the actual production requirements and meet the actual production needs. The composition, design structure and steam tracing design of the steam tracing system are analyzed to meet the different chemical production requirements in the chemical test process.
The design of steam tracing pipe requires scientific and technical personnel to follow the actual needs, and ensure that the design of steam tracing pipe can improve the efficiency of chemical pipe and maximize the heat transport effect. In actual design, it is necessary to fully consider the limitations of specific process media, determine the heat tracing coefficient and design quota, so that the process media will not be blocked, condensed and other problems during operation, and avoid affecting the effect of chemical process.
1. Importance of heat tracing design of chemical process pipeline
The purpose of pipeline heat tracing design is to improve the efficiency of chemical pipeline and ensure that the chemical pipeline can achieve the maximum heat transport effect. At present, the overall energy consumption of chemical production is very high. In order to implement China’s sustainable development strategy and save energy, environmental protection and consumption in production, it is urgent to optimize the pipeline heat tracing design to achieve the goal of energy conservation and environmental protection. The heat tracing design of chemical process pipeline includes several design points of external heat tracing pipe, internal heat tracing pipe, jacketed heat tracing pipe and electric heat tracing pipe. Proper design pipes are used in the design to avoid excessive consumption of chemical heat energy, thus reflecting the purpose of saving chemical energy and realizing the goal of chemical production and operation.
In the actual production process, the heat tracing design of chemical process pipeline is a fully automatic heat tracing design to meet the loading requirements of special chemicals, and the thermal insulation effect achieved is far better than that in the traditional heating management design. Indirect heating is the principle of heat tracing pipe heating, which can ensure the safety of system operation and reduce resource consumption. In the design, the difference in the content of heat tracing design is based on the difference in the use of heat tracing medium. At present, in the specific design, people generally attach importance to the design of electric heat tracing and steam heat tracing. The design of the heat supply distribution station is the focus and core of the design. The specific parts are instruments, valves, supports, etc. Scientific and technical personnel determine the location of the distribution station according to the design content in the design, and determine the location of the heat supply distribution station at the platform, column, wall, etc. A reasonable design of the location can facilitate the smooth implementation of the distribution work and effectively improve the work efficiency. In the design, the length of heat tracing pipe can be shortened, and a sliding frame and a fixed support can be set. At present, various new materials and technologies have emerged in the market. The design of these scientific and technological data needs to consider the use of various valves, such as stop valve, shut-off valve, steam trap, etc., among which steam trap is the key design content in the design of steam tracing distribution station. In the specific design, detailed planning and design shall be carried out for the location of tracing pipe and header pipe, valve interface, length, etc. according to the actual situation.
2. Key points and requirements for design of chemical process pipeline steam tracing pipe
Unreasonable design and improper installation of the tracing pipe will lead to the problems of medium solidification and poor transportation in the chemical plant, which will affect the equipment production. In the actual operation process, these will affect the production efficiency and production quality, and even directly affect the production of chemical enterprises. In the actual business survey, it was found that the unreasonable design and inadequate installation were mainly caused by human factors. In the design content, a comprehensive analysis should be made, and the design should be carried out according to the needs. The medium efficiency should be fully and reasonably analyzed. The designer should use the external heat tracing pipe to maintain the material temperature in the design; If the medium is not corrosive, the designer should design a heat tracing device outside to ensure the temperature of the material by using the external heat tracing pipeline. If the medium is ordinary, the design form can be ignored during design. The heat tracing device can be set inside or outside. In the process of design, the length and spacing of tracing pipes shall be determined according to the requirements of different chemical processes and equipment.
Specific requirements for heat tracing and insulation design of pipes: First, the external heat tracing pipes are generally used in the design of heat tracing pipes. When designing heat tracing pipes, designers need to determine the number of heat tracing pipes in close accordance with production requirements, and refer to the temperature, pressure and other parameters of heat tracing pipes. Considering the actual needs, especially the requirements for thermal insulation, the steam temperature is usually increased to make it greater than the medium thermal insulation parameters. At this stage, it is necessary to consider the possible changes of the medium itself, such as the focal point and freezing point of the medium, and ensure that the medium will not block the pipeline.
3. Design analysis of steam tracing system
3.1 Composition of steam tracing system
During the whole process production and operation, the participating equipment include steam header and tracing pipe, steam tracing pipe and outlet pipe, condensate water pipe and header, steam distribution station and condensate collection station. The whole process production is relatively complex and comprehensive. The designer needs to fully consider it from the overall perspective when designing the heat tracing pipe to make it more reasonable.
3.2 System design process
(1) Design of heat tracing station.
The heat tracing station is mainly composed of steam distribution station and condensate collection station. The heat tracing station is generally located in the middle and plays the role of heat tracing. It is a bridge for splicing pipes. Therefore, the location of the heat tracing station should be fully considered in the design. Generally, the heat tracing station is set beside the wall and column to provide support for heat tracing. In the actual application process, the heat tracing pipes connect many pipes. To ensure that the pipes are not disordered, orderly and orderly, this is also the key content that designers and technicians must fully consider.
(2) Design of steam distribution station and heat tracing header.
In the design of both, it is necessary to determine the quantity and quality, and calculate according to the formula. The final parameter results will affect the determination of the number of steam distribution stations. When designing the steam station, the radius is 5m, and the number of heat tracing gas supply stations in this location is not allowed to exceed 3. According to this rule, if the actual number of heat tracing gas supply groups is relatively small, the designer should change the location of the heat tracing pipe to connect it with the first length of steam. The designer also needs to fully consider the quantity and quality of steam branches, determine the number of branches and the diameter of distribution inlet header.
(3) Tracing pipe design.
The design shall consider both size and quantity. The design of these parameters is directly related to the production process. The designer needs to determine the pipe diameter of the tracing pipe according to the specification requirements and calculate the pipe diameter according to the regulations. In the design content, the maximum length of the tracing pipe design shall be fully considered, and the steam pressure, diameter and other factors shall also be fully considered in the design of the tracing pipe length. The main function of the tracing pipe is to connect the heat tracing distribution station, collection station and other equipment. The starting point of the tracing pipe should be located at the distribution station, the end point of the tracing pipe should be as close to the collection station as possible, and the maximum length of the tracing pipe before supply should be less than 15m. In the design, the length of the heat tracing pipe shall be consistent as far as possible. The connection between the tracing pipe and the condenser needs to control the distance between the output point of the tracing pipe and the condenser. The pipes shall be used for connection. However, in the specific design, the total length shall not exceed the length range.
(4) Design of condensate station and heat tracing condensate header.
No more than 3 pipes are allowed to connect the condensate station, and the pipes shall be set reasonably. In the actual management content, the design of the condensate station and the distribution station should consider the same direction, and the spare joint should be set to ensure the safe operation of the equipment. The branch number of condensate station is different, and the diameter of branch number, header and outlet header are also different in specific design.
3.3 Steam tracing design
The design content of steam tracing is to realize the control of the internal temperature of the pipeline through the work flow of steam distribution station and steam pipeline. In the working environment of condensate process pipeline, the common temperature control pipeline is steam tracing, whose main function is to prevent steam from forming condensate and causing corrosion to the process pipeline. In the steam tracing system, the functions of the distribution station are relatively centralized, mainly in distribution and setting. In terms of design, there is no difference between the steam tracing distribution station and the conventional distribution station, and the distribution station is reasonably set according to the location of the wall and column. In addition to fully considering the actual needs of the heat tracing distribution station in the design, it is also necessary to fully consider the whole area. The actual operation of the steam distribution station shall use vertical and horizontal pipes, which can facilitate the operation of equipment and avoid heat loss. The design of steam distribution station shall consider uniform distribution, and reserve the outlet hole to access the heat tracing pipe, so as to ensure that the steam can also operate normally in case of emergency. The design of the condenser must meet various process requirements. For example, the design of the tracing pipe uses vertical installation, which can avoid corrosion of the pipe, realize rapid collection of condensate and ensure system operation. The focus of steam tracing work is the design of steam tracing pipes. Designers must have a holistic view and fully consider various design points. For example, attention should be paid to the design of valves. The materials of valves should be the same as those of pipes. Valves can ensure drainage quality.
3.4 Electric tracing design
The designed pipeline is a kind of heating pipeline frequently used in the process pipeline, which is heated by electric heating, resistance heating, induction heating and other pipelines. The advantage of this design is that it does not require frequent daily maintenance, and has strong construction operability and high safety. In the process of continuous development, people have made more in-depth research on the heat tracing technology of chemical process pipeline, and put forward the electric heating technology. The application of this technology has improved the utilization efficiency of the system and significantly reduced the energy consumption.
Electric heat tracing design is an advanced process. The design of heat tracing capacity should be added in the design. Only by ensuring sufficient capacity can we provide more effective support for chemical production, improve the utilization rate of pipelines and reduce the consumption of energy resources. Insufficient capacity in the design will easily affect the utilization rate of the pipeline and increase the waste of heat energy. In this case, the heat tracing capacity to be consumed should be accurately calculated on the premise of ensuring that the heat tracing capacity meets the specific work requirements. In the specific design, the three-dimensional computer model is used to carry out the electrical heat tracing design, reasonably design the distribution station, heat tracing pipe, header, etc., pay attention to the planning of location, data and other aspects, and ensure that the design is clear and reasonable.
To sum up, the chemical process involves different chemical media with different morphological changes, and there are strict requirements for environmental temperature, humidity and pressure. In summary, it is necessary to fully consider the operating requirements of chemical media, data, parameters, etc. in the design, clarify the design key points, and take reasonable measures to ensure the specific design effect.
Author: He Feng, Yu Yuxiang