Negative-pressure and inert gas displacement method for large-scale spherical tank

Abstract

A negative-pressure and inert gas displacement method for a large-scale spherical tank is disclosed. According to the method, the capacity of the spherical tank bearing outer pressure is obtained based on the material of the spherical tank, the tank capacity and the tank wall thickness, and then the gas displacement and the negative-pressure limit of an arranged vacuum pump group are calculated out based on the capacity of the spherical tank, and the method comprises the following steps: firstly using a vacuum pump to vacuumize the spherical tank, injecting nitrogen into the spherical tank to have the pressure of 0.01 MPa after the spherical tank is vacuumized to have the pressure of 1000 Pa, then performing secondary vacuumizing to have the pressure of 6000 Pa and then injecting nitrogen into the spherical tank to have the pressure of 0.02 MPa (only on spherical tank in one tank group has the pressure of 0.4 MPa after being filled with nitrogen), so as to enable the oxygen content in the tank to be less than 1% which far reaches the prescribed displacement requirement. By using the displacement method, the displacement cost is relatively low, no adverse influence is caused on subsequent material operation after displacement is finished, the displacement time is substantially shortened, benefit is generated from the spherical tank in advance, a large amount of time is saved for subsequent displacement for annual inspection, the utilization rate of the spherical tank is improved, and the spherical tank benefit is maximized.

Description

technical field [0001] The invention relates to a method for replacing oxygen with an inert gas in a large spherical tank in the chemical industry. Background technique [0002] At present, there are roughly two types of large-scale spherical tank replacement in the industry. 1. Direct replacement of inert gas. This method consumes a large amount of inert gas, takes a long time to replace, and the replacement of the pipeline connected to the tank is not complete. 2. Water replacement method. After the replacement is completed, the water content exceeds the standard, and there is water in the pipeline connected to the tank. Contents of the invention [0003] In view of the above disadvantages, the present invention provides a negative pressure plus inert gas replacement method for large spherical tanks. [0004] The present invention is achieved through the following technical solutions: a negative pressure plus inert gas replacement method for a large spherical tank, the ...

AI Technical Summary

Problems solved by technology

[0002] At present, there are roughly two types of large-scale spherical tank replacement in the industry. 1. Direct replacement of inert gas. This method consumes a large amount of inert gas, takes a long time to replace, and the replacement of the pipeline connected to the tank is not complete.

Images