Multi-bed gasifier high-temperature equipment and pipeline stress analysis Ye Shuixiang Zhao Shijun 2, Tang Shenglian 2 cyclone separator, waste heat boiler and ancillary pipelines for overall modeling and stress analysis, comparing the advantages and disadvantages of three different pipeline arrangements. According to the requirements of the American ASMEB31.3 process pipeline standard and engineering practice experience, considering the stress of the pipeline under the load of internal pressure, dead weight, temperature, earthquake, wind load and other loads, and through the combined effect of the load conditions, each The stress distribution of the pipeline under working conditions, determine the type of each spring support, and calculate the pipeline load from the pipeline to the equipment nozzle.
The core equipment of a company's multi-stage staged conversion fluidized bed coal gasification pilot plant is a gasifier, three-stage cyclone separator, waste heat boiler and auxiliary piping. The coal entering the furnace enters from the lower part and the upper part of the gasifier respectively, at a high temperature of 1000 ~ 1 100t! Next, it reacts with the gasification agent to form ash residue aggregates and crude gas. The agglomerates of ash and slag are discharged from the gasification furnace through the slag lock, and the crude gas enters the three-stage cyclone separator. The entrained fine powder is captured and returned to the gasification furnace for further gasification through the feed legs and the return valve. After dedusting, the high-temperature gas enters the waste heat boiler for waste heat recovery.
The purpose of 1CAESAR overall stress analysis. Because the multi-stage grading conversion fluidized bed coal gasification pilot plant is based on the original pressurized ash fusion fluidized bed powder coal gasification pilot test platform, it is restricted by the space of the original platform, equipment and pipelines. Compact layout, using CAESAR pipeline stress analysis software to model the core part of the pilot plant, which can analyze and calculate the stress distribution under internal pressure and various loads; analyze and compare the stress of the pipeline system under various layout schemes The level provides a basis for selecting the best solution; calculates the pipe load of the pipe to each equipment nozzle and provides external load for equipment design; calculates the load and displacement of the spring support hanger and determines the spring support hanger model.
2 Comparison and analysis of the three schemes Due to the compact layout of each equipment, how to pipe so that the pipeline can not only meet the process requirements, but also to meet the stress strength conditions of the pipeline under various working conditions is the most difficult problem. For this reason, the piping engineer has proposed three Assistant Engineer of Dalian Design & Research Institute Co., Ltd., Dalian, Liaoning 116600, Senior Engineer of Dalian Design & Research Institute Co., Ltd., Dalian 116600, Liaoning, China 1—3 third cyclone separator; 2—pipe three; 3—pipe two; 4—pipe i; 5-―the first cyclone separator; 6―the first cyclone support; 7―the one leg return pipe; 8―the three cyclone support; 9-1-the second cyclone separator; 10―the second cyclone support; 11-12 the two legs Return pipeline; 12—fixed support for the gasifier; 13—pipe four; 14—a waste heat boiler; 15—fixed support.
Schematic diagram of the overall structure of the gasifier, cyclone separator, waste boiler and auxiliary piping.
2.1 Plan: The fixed support and expansion joint gasifier and three cyclones are supported by the fixed support on the steel structure frame, and the expansion joint is added on the long pipeline from the three-stage cyclone to the waste heat boiler to absorb the heat. The amount of deformation caused by expansion, thereby reducing pipeline stress.
The advantage of this solution is its simple structure and easy installation. However, because the expansion joints must be replaced at intervals, it is not conducive to maintenance, and because the inner wall of the pipeline needs to be laid with refractory and insulation materials, the expansion joints will be bent by tension and compression during the deformation coordination of the pipe system, resulting in the inner wall The refractory material is destroyed, and the high-temperature medium will directly contact with the metal pipe, which will reduce the allowable stress of the pipe and eventually damage the pipe.
2.2 Scheme two: fixed support plus n-shaped elbow gasifier and three cyclones are fixedly supported on the steel structure frame, and n-shaped elbows are added to the long pipeline from the third cyclone to the waste heat boiler. Tube to absorb the amount of deformation caused by thermal expansion, reduce pipeline stress.
The scheme is also simple in structure and easy to install, but due to the space limitation of the original frame, the n-shaped elbow will exceed the frame and interfere with the frame beam. Therefore, although the scheme can meet the process and stress strength conditions, it cannot be used in the pilot plant achieve.
2.3 Scheme 3: The spring support for the cyclone separator In this solution, the gasification furnace and the waste heat boiler are supported on the steel frame with a fixed support. The three cyclone separators are supported by the spring support, and the deformation of the spring support is used to Absorb thermal expansion and reduce pipeline stress.
1—The third cyclone separator; 2—the spring support; 3—the pipe to the waste pot; 3—the waste heat boiler; 5—the fixed support.
Scheme 3: Schematic diagram of the use of a spring support for the cyclone separator. Although the scheme is more complicated in structure than the first two schemes, it takes up less space and can be installed on the original frame structure. After calculation, the pipeline stress can meet the stress strength condition, so This scheme is practical and feasible. The multi-stage staged conversion fluidized bed coal gasification pilot plant developed by a company adopts this scheme.
3CAESAR stress analysis calculation 3.1 establishment of pipeline load 1 calculated pressure and calculated temperature The operating pressure of the gasifier is 3.0MPa, the operating temperature inside the gasifier is about 1200 feet, but because the equipment and the inner wall of the pipeline are covered with refractory materials, The calculated pressure of the pipeline is 3.0 MPa, and the calculated temperature is 150 feet.
In CAESAR, the wind load is calculated by multiplying the exposed area of ​​the pipe by considering the insulation layer and the wind direction angle by the equivalent wind pressure and the shape factor of the pipe. The user can generally use three methods to calculate the equivalent wind pressure. The first type is calculated using the ASCE7-2005 standard, the second type is calculated using the wind pressure and height relationship table, and the third type is calculated using the wind speed and height relationship table. The total wind calculation formula on the unit: In this project, since the relationship between the wind pressure and the height of the test base has been measured, the second method is used to calculate the wind pressure and the wind force on the unit. The wind shape factor is 0.6. The relationship between wind pressure and altitude at a certain base can be analyzed by CAESAR software using two methods: static calculation and dynamic calculation. The method of applying static seismic load is similar to wind load. The magnitude of seismic load is proportional to the weight of the element. This project uses a static calculation method, and the seismic acceleration is 0.2g. 3.2 Load combination conditions and calculations The basic load conditions can be combined in CAESAR using conditional algebraic combinations to form various combination conditions.
Normal load conditions should take into account load components such as self-weight W, displacement, temperature T, pressure P and spring additional force H, and spring load conditions HgR, operating conditions (OPE, continuous conditions SuS, and according to Expansion conditions are combined by operating conditions and continuous conditions. The accidental loads include wind loads and seismic loads. According to the provisions of ASMEB31.3, wind loads and seismic loads are not considered to be superimposed, and are combined separately with normal operating loads.
In addition to the load components such as self-weight disk, displacement D, temperature T, pressure P, and spring additional force 0, wind load conditions also include wind load components. The wind load direction in this project is determined by the direction with the highest proportion in the wind rose diagram.
In addition to the load components such as self-weight disk, displacement D, temperature T, pressure P, and spring additional force 0, seismic load conditions also include X, Y, and Z three-way seismic components.
The basic operating conditions provided by CAESAR are continuous operating conditions SuS, operating conditions OpE, thermal expansion conditions Exp and accidental operating conditions (OC0, users can use these basic operating conditions to combine various required operating conditions to check the order Stress and secondary stress, calculating the force and displacement of various constraints on the pipeline under different working conditions, etc., have extremely high flexibility and provide users with great convenience.
After the combination of the above working conditions, the stress distribution, end point displacement and constraining load of the pilot device under various working conditions can be obtained from the CAESAR output file. The spring support type is determined by calculating the load and displacement of the spring support See Table I, judging from the result file, the piping layout of scheme three is reasonable, which not only meets the process requirements, but also meets the stress intensity conditions.
Table 1 Selection of spring support for cyclone separator Position spring model B / T8130.2-1999 Quantity Vertical displacement (upward) mm Working load Installation load Spring stiffness (N / cm) Horizontal displacement mm Maximum height mm Minimum height
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