No pressure in the cylinder before the air compressor of air separation unit starts

Another part of the nitrogen vaporized in the liquefier is heated up to a certain temperature in the high pressure heat exchanger and pumped out to the low pressure nitrogen press, the nitrogen separated by the gas-liquid separator is also heated up by the high pressure heat exchanger and then goes to the low pressure nitrogen press, compressed to a certain pressure by the low pressure nitrogen press and then back to the high pressure heat exchanger for heat exchange with liquid air separat...

Special pressure-bearing equipment generally bears internal pressure, that will cause tensile stress inside the shell, which is called working stress. The working stress is directly proportional to the pressure and diameter, and inversely proportional to the vessel wall thickness. The axial stress is half of the circumferential stress. Therefore, for cylindrical vessels, the stress of longitudinal weld is twice that of girth weld. Because the geometric shape of the spherical shell is symmetrical to the spherical center, and the axial stress is equal to the circumferential stress in numerical value. Therefore, the wall thickness of the spherical vessel can be reduced by half as much as that of the cylindrical vessel under the same pressure and diameter.