The design example referred to herein is a primary cooler for use in large reciprocating new hydrogen compressors required in the petrochemical refinery sector.
1.1 Cooler design input and preliminary structure determination
The original data of the cooler is: standard flow rate 30300Nm 3 /h, intake air temperature 40, gas composition: hydrogen, relative humidity 10; compressed gas is cooled from 110 to 40, the required pressure drop is less than 0015 MPa; the cooling water temperature is 30 liters. To 38, the maximum pressure drop is allowed to be 005 MPa; the gas/water side fouling coefficient is 0.0002/0. 0008 m 2 .
1.2 Process calibration of the cooler based on known design parameters
Pay attention to the following points in the process of inputting parameters:
(1) The input of the physical parameters of the process medium in the process parameters is very important: for this example a single medium can be selected from the software database. However, for the compressor cooler, in many cases, the composition of the medium is a mixture, and it is difficult to select a suitable substance as a process medium from the database. In this case, the user-defined composition # can be selected, and the following key process parameters need to be input: process The critical temperature of the medium, critical pressure, average latent heat, gas at operating temperature, liquid phase density, viscosity, specific heat, heat transfer coefficient, etc. In addition to the APSEN program to select the appropriate equation of state to simulate the physical properties of the mixture, the most reliable method is obtained through the literature or the patent processor's process package file.
(2) In the input process parameters, the first few stages of the multi-stage compressor should consider the effects of saturated steam cooling and partial condensation. This is different from conventional heat exchanger calculations, which are often overlooked, resulting in insufficient calculated cooling area.
(3) The input of structural parameters should be noted: the national standard GB151 shell-and-tube heat exchanger % clearly defines the heat exchanger structure size, but the general international business heat transfer software is designed according to foreign standards such as TEM A. The heat exchanger has a certain difference between the two. Therefore, the GB15 dialog box for each structural size specification of the heat exchanger should be found in the software program. Enter these values ​​according to the requirements of GB151, such as the spacing between the tube circle and the inner wall of the heat exchanger shell side. The heat exchangers in accordance with national standards can be designed only by the distance of the inlet on the shell side.
1.3 adjustment parameters
After completing the parameter input, run the software, the program will give a calculation report. According to the report prompts, we need to pay attention to the following control parameters and make corresponding adjustments. Modify the parameters and re-run to get reasonable results:
(1) The heat exchange area, design margin, total heat transfer coefficient, corrected temperature difference and other parameters meet the requirements;
(2) On the gas side, the water side flow velocity and the Reynolds number are within a reasonable range;
(3) The pressure drop meets the set requirements;
(4) In the flow path analysis, the proportion of effective flow is reasonable;
(5) No tube beam vibration, acoustic vibration; no fluid induced vibration due to Karman vortex, turbulent flow, fluid instability and other reasons.
1.4 Analysis of calculation results
In the calculation report information column, no abnormal information is given, and the cooler is in stable operation, and the control parameters are in good agreement. It is also proved from the feedback of the use unit that the cooler meets the design requirements in the actual production process and works well.
2 Conclusion
The application of international general business software for the process calculation of the compressor cooler can:
(1) Accurately calculate the required heat exchange area and design margin;
(2) Accurately analyzing the physical change process of the process fluid in the heat exchanger tube;
(3) Calculate the true circulation amount and gasification rate;
(4) Accurately calculate the resistance loss of the tube and shell-side medium;
(5) Various reports of cooler operation, including vibration reports, stable operation reports, and fluid flow rate and flow pattern reports, are provided in the calculation information column, which is easy to optimize the design of the cooler. Therefore, this method has strong practicability and promotion value in the field of compressor cooler process calculation.
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