Two-stage back heating multi-strand winding pipe type heat exchange device for low-temperature liquid nitrogen

Abstract

The invention mainly relates to the technical field of synthesis ammonia and low-temperature liquid nitrogen, and relates to the technology of a two-stage back heating multi-strand winding pipe type heat exchange device for the low-temperature liquid nitrogen. Through N2-H2 synthesis gas which is in the outlet of a three-stage cooling device in the low-temperature liquid nitrogen process and synthesized by H2 at the temperature of 130.2 DEG C below zero and the pressure of 1.78MPa and N2 at the temperature of 130.2 DEG C below zero and the pressure of 5.14MPa and through waste nitrogen N2-Ar-CO-CH4 at the temperature of 130.2 DEG C below zero and the pressure of 0.15MPa, N2 at the temperature of 38 DEG C below zero and the pressure of 5.8MPa is cooled to be N2 at the temperature of 127.2 DEG C below zero and the pressure of 5.7MPa, and purified gas H2-N2-CO-Ar-CH4 washed by low-temperature methanol is cooled to be purified gas at the temperature of 127.2 DEG C below zero and the pressure of 5.24MPa, namely, the incoming high-pressure N2 and the purified gas washed by the low-temperature methanol are cooled through cooling capacity back heating of the N2-H2 synthesis gas of the outlet of the three-stage cooling device, high-pressure H2 and the waste nitrogen, and the temperature condition is provided for the three-stage cooling device. The two-stage back heating multi-strand winding pipe type heat exchange device for the low-temperature liquid nitrogen is compact in structure and high in heat exchange efficiency and can be used for solving the technical problems of the two-stage six-strand four-bundle winding pipe type heat exchange for the low-temperature liquid nitrogen with the temperature ranging from 38 DEG C below zero to 127.2 DEG C below zero, and the low-temperature heat exchange efficiency of a low-temperature liquid nitrogen process system is improved.

Description

Technical field [0001] The present invention is mainly applied to the technical field of low-temperature liquid nitrogen process equipment for synthetic ammonia, and relates to two-stage six-stream four-tube bundle spiral-wound tube heat exchange equipment technology for low-temperature liquid nitrogen, and applies -130.2℃ at the outlet of the third-stage refrigeration device in the low-temperature liquid nitrogen process. , 1.78MPa H 2 , -130.2℃, 5.14MPa N 2 —H 2 Syngas and -130.2℃, 0.15MPa N 2 -A r —CO—CH 4 Pollution nitrogen cooling-38℃, 5.8MPa N 2 To -127.2℃, 5.7MPa and cooling from low temperature methanol process -63.3℃, ​​5.26MPa H 2 -N 2 —CO—A r —CH 4 Purify the gas to -127.2℃, 5.24MPa, that is, use the N at the outlet of the three-stage refrigeration device 2 —H 2 Syngas, high pressure H 2 And the cooling capacity of polluted nitrogen 2 , The purified gas washed with low-temperature methanol provides temperature conditions for the three-stage refrigeration device; its com...

AI Technical Summary

Problems solved by technology

First of all, most of the current low-temperature liquid nitrogen washing process systems adopt the overall heat exchange method, which connects the three-stage refrigeration process as a whole. The height of the heat exchanger can reach 60-80 meters, and the heat exchange efficiency has been significantly improved. The thermal process is too complicated, and the volume of heat exchange equipment is too large, which brings serious inconvenience to processing, manufacturing, on-site installation and transportation, and once there are problems such as pipeline leakage, it is difficult to detect, and it is easy to cause the entire heat exchanger to be scrapped and the complete set of process equipment to stop production , and the present invention solves LN from the three-stage heat exchange equipment 2 Start with the problem of pre-cooling and liquefaction, and focus on solving the low-temperature heat transfer problem of the second-stage refrigeration device

Finally, the inlet temperature of the purified gas in the middle section is -63.3°C, and the logarithmic average temperature difference is 3°C. If -63.3°C is set as the inlet temperature of the secondary refrigeration, the maximum temperature difference of the primary refrigeration is 108.3°C, and the maximum temperature difference of the secondary refrigeration is 66.9°C , the maximum temperature difference of the third-stage refrigeration is 66.2°C. After comparing the three temperature differences, the first-stage refrigeration device has a larger volume and higher heat transfer load than the second-stage and third-stage refrigeration devices due to the large temperature difference of the first-stage refrigeration. Therefore, in order to reasonably design the three-stage type refrigeration device, it is necessary to reasonably distribute the heat exchange temperature difference

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