Nitrogen and vacuumizing combined pre-startup replacement method for pressure swing adsorption decarbonizing device

Abstract

The invention relates to a pre-startup replacement method for a pressure swing adsorption device after installation or maintenance is finished. After pipes are purged by compressed air and leakage test and pressure test are qualified, towers are fully filled with air. The method includes: step one, opening program control valves of adsorption towers and program control valves of pressure equalizing equipment, vacuumizing until the pressure is smaller than or equal to -0.07MPa, and closing all vacuumizing program control valves; step two, feeding nitrogen by nitrogen pipelines on outlet main pipes at tops of the adsorption towers through all open outlet program control valves from the outlet main pipes of the adsorption towers until the pressure is 0.005MPa, emptying replacement outflow gas through emptying pipes arranged at feed gas inlets, stopping feeding nitrogen, and closing nitrogen valves, wherein the gas emptying volume accounts for 10%-20% of the total volume of each vessel, the oxygen content of each main feed gas inlet pipe reaches 2.5%, the oxygen content reaches 0.2% after the two steps are repeated, the oxygen content reaches 0.04% after the two steps are repeated again, and repeating times is determined according to required oxygen concentration.

Description

technical field [0001] The invention relates to the field of chemical industry, and is a method for effectively utilizing inert gas and reducing gas consumption. Background technique [0002] 1. For chemical equipment with a working pressure of 0.3MPa or more, the general replacement method is to set up a nitrogen replacement pipeline at the main pipe of the raw material gas inlet, so that the nitrogen gas is passed into the device at a pressure of 0.3MPa, and the method of venting the air after passing through all the equipment Oxygen, this method works and is used by almost all chemical plants. The method is safe, effective and saves nitrogen when it is applied to the equipment with straight-through import and export. There is also a method of setting up a nitrogen replacement pipeline in the product gas outlet main pipe, allowing nitrogen to flow into the device at 0.3MPa, flow through all the equipment, and set up a venting pipeline at the inlet to drive away the oxygen...

AI Technical Summary

Problems solved by technology

[0003] 2. For the pressure swing adsorption device, the above method has great defects because the pipeline of the pressure swing adsorption device is intricate, there is no simple direct flow channel, there are many dead ends between the pipeline and the equipment, and it is usually difficult to complete the replacement of the cecum structure

For better replacement, it is necessary to set up replacement vents on almost all the main pipes and equipment to ensure that there is no dead angle in the replacement, the leakage points will naturally increase, the management difficulty will increase, and the operation will be inconvenient

For less than 4 adsorption towers, direct circulation replacement is also feasible due to less pressure equalization pipelines and less equipment. However, for devices with more than 10 adsorption towers, or even 40 adsorption towers working at the same time, the replacement method uses Conventional circulation replacement is extremely difficult. For an adsorption device with 18 towers, 30 cubic meters per tower, and 5 pressure equalization pipes, the nitrogen flow rate is 1000 standard cubic meters per hour, and the replacement time is generally more than 12 hours.