Directly-series-connected one-step pressure variation adsoption process

Abstract

The direct series-step pressure swing adsorption process disclosed by the present invention has at least three adsorption tower groups in the process system, and each adsorption tower group is directly connected in series by two adsorption towers, and the raw material gas enters a certain tower group to communicate with each other. The first and second-stage adsorption towers are adsorbed, and the difficult-to-adsorb components are discharged from the top of the second-stage tower as product gas 1. When the easily-adsorbed components in product 1 are about to exceed the standard, the output will be cut off, and then the tower group will be combined with other adsorption towers. Tower group or / and pressure equalizing tower, a certain adsorption tower in other adsorption tower groups and a certain tower in this tower group and a certain adsorption tower in other adsorption tower groups carry out pressure equalization drop, after the final pressure equalization drop, will The gas evacuated by the first-stage tower in the tower group against the direction of the air intake is taken as product 2, and the gas evacuated by the second-stage tower in the tower group is recovered against the direction of the air inlet, followed by pressure equalization and final charging, and so on. . The invention can not only obtain high-purity and high-yield easily-adsorbed components and difficult-adsorbed components, but also reduce construction costs, operating costs and energy consumption.

Description

1. Technical Field [0001] The invention belongs to the technical field of pressure swing adsorption gas separation, and specifically relates to a direct series-type one-step pressure swing adsorption process, that is, a process for realizing the pressure swing adsorption process in a set regeneration cycle system consisting of at least three adsorption tower groups. Each adsorption tower group consists of two adsorption towers directly connected in series. 2. Background technology [0002] In order to separate the mixed gases with different separation coefficients produced in the chemical production process and to recycle them, various pressure swing adsorption methods have appeared in the technical field of pressure swing adsorption gas separation, such as patent publication numbers CN1140418A, CN1235862A, CN1334135A , CN1334136A, CN1342509A, CN1347747A, CN1248482A disclose various tandem pressure swing adsorption methods. These pressure swing adsorption methods all use all the ...

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Problems solved by technology

Compared with the one-step parallel adsorption method, they can improve the utilization rate of the adsorbent and the purity of the difficult-to-adsorb components to a certain extent, but there are still the following disadvantages: 1. If a large-scale pressure swing adsorption system requires multiple towers to feed in simultaneously, it will not be able to Ensure that the easily adsorbed components are distributed in the same concentration gradient in the two-stage (set) adsorption tower, resulting in low utilization of the adsorbent in the second-stage (set) adsorption tower

2. There is a lack of organic connection between the adsorption towers of the two-stage (set) system, and the cooperation between them cannot be fully used to increase the number of direct pressure equalization, resulting in high vent pressure and large vent volume, so that the easily adsorbed components The yields of the less adsorbed components are lower

3. The two systems occupy a large area, the system is complex, there are many program-controlled valves, the maintenance workload is large, the trouble-free running time is short, and the construction investment is large, etc.

However, due to the initial stage of adsorption in this process, the easily adsorbable components form their own concentration gradients in the two towers in series, and the gas containing low-concentration easily-adsorbable components output from the front-stage tower enters the bottom of the latter-stage tower and contains high-concentration easily-adsorbable components. After part of the adsorption bed, the high-concentration easily adsorbed components will inevitably be replaced and rushed to the top of the next-stage adsorption tower, thereby polluting the adsorbent at the top of the next-stage adsorption tower, resulting in incomplete separation and inability to remove difficult The purity of the adsorbed components is very high

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