Full-temperature-range simulated rotating moving bed pressure swing adsorption FTrSRMPSA gas separation and purification method

Abstract

The invention discloses a full-temperature-range simulated rotating moving bed pressure swing adsorption FTrSRMPSA gas separation and purification method, and relates to the field of pressure swing adsorption PSA for gas separation and purification. The adsorption tower is provided with n axial flow fixed bed layers and is arranged on an annular rotating tray with the rotating speed omega 2; the rotating valve is provided with m channels and is arranged in the center of the annular tray and rotates at the rotating speed omega 1; the process pipeline is connected between the upper part and the lower part of the adsorption tower and the rotary valve through a built-in pipeline of the circular tray; the driving mechanism is used for correspondingly driving the circular tray and the rotary valve to rotate and regulating and controlling the rotating speeds omega1 and omega2 of the circular tray and the rotary valve; according to the device, the high purity and the high yield of a simulated rotary PSA process carried out on the basis of an axial flow fixed bed layer for PSA separation of each raw material gas and purification and extraction of product gas are realized.

Description

technical field [0001] The invention relates to the field of pressure swing adsorption PSA for gas separation and purification, and more particularly to the technical field of full temperature range simulated rotary moving bed pressure swing adsorption FTrSRMPSA gas separation and purification. Background technique [0002] At present, the PSA method for gas separation and purification is mainly divided into a fixed adsorption bed (Fixed Bed-FB) in which the adsorbent is fixed in the bed according to the different ways of the adsorbent loaded in the adsorption tower during the adsorption and desorption cycle operation. ), the moving bed (Moved Bed-MB) in which the adsorbent is not fixed and moved in the adsorption tower. Among them, the fixed bed is divided into axial flow fixed bed (AFB) and radial flow fixed bed (RFB). Beds include Circulating Bed (CMB), Fluidized Bed (FMB), Simulated Moving Bed (SMB), Rotating Moving Bed (RMB), etc. Among them, Axial Flow Fixed Bed (AFB) ...

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Problems solved by technology

[0006] ③Axial flow FB-PSA process can obtain higher purity product gas, but its yield is reduced due to the high dead space ratio in the tower due to the large amount of adsorbents filled in the adsorption tower, and there is an obvious " The higher the purity of the product, the lower the yield, and vice versa", the contradiction between "purity and yield are inversely proportional" is one of the most obvious defects of the FB-PSA process, especially when compared with traditional absorption, extraction or rectification Compared with other technologies, it has disadvantages in terms of economic benefits, which limits its wide application.

However, to increase the number of pressure equalization times, the number of adsorption towers must be increased, and the corresponding program control valve or regulating valve of each adsorption tower will also increase, which not only increases the investment and cost, but also leads to the stability of the entire device. decreased reliability

[0008] ⑤Switching of the program control valves for each fixed-bed adsorption tower will cause instantaneous pulses of the flowing gas in the adsorption bed, which will cause a large disturbance to the uniform laminar or advective gas flow distribution required for mass transfer, affecting the transfer rate. Mass efficiency, the higher the switch switching frequency, the more frequent the disturbance, the greater the impact on mass transfer, especially when the adsorption pressure is high, when the pressure equalization, reverse discharge, final charge, flushing or vacuum desorption, the adsorption tower The pressure difference of each desorption step should not be too large, otherwise it will easily cause more intense air flow disturbance, and in severe cases, the adsorbent will be pulverized and the device will be damaged.

Generally, the problems caused by excessive pressure changes are alleviated by adding adsorption towers or adding corresponding program control valves and regulating valves, but the stability will be affected.

[0009] ⑥The fixed bed adsorption process is very easy to produce deep adsorption due to the long axial mass transfer path for those adsorbent components with high polarity, which makes desorption very difficult, which will further reduce the service life of the adsorbent. Dropped significantly

Yet this invention also has some obvious defects: a) the limitation of adsorption and desorption cycle operation steps: because this invention is based on multi-channel rotary valve as process gas enters and exits the distributor of each fixed-bed adsorption tower, thus, the rotary valve channel The number is directly related to the number of adsorption towers and the number of steps of adsorption and desorption, so as to form a continuous cycle operation of adsorption and desorption, such as 6 towers, 9 towers or 12 towers, etc., the number of channels of the rotary valve must be Fixed to 9~12, 12~24, 24~32 channels, etc.

Due to the circulation or fluidized movement of the adsorbent, the wear and pulverization of the adsorbent are serious, and the cost of transporting solid adsorbent particles is high, which has become the most troublesome problem in the classical moving bed adsorption process, and greatly limits its application. ; At the same time, some advantages of the traditional fixed bed adsorption process are basically abandoned, including the difficulty in realizing pressure swing adsorption

In order to overcome the above-mentioned fatal shortcomings of circulating bed and fluidized bed adsorption, the rotary pressure swing adsorption (RWPSA) process of rotary moving bed adsorption suitable for gas separation and purification has been developed abroad. The adsorbent is fixed in the container without relative movement. , but the adsorbent as a whole is rotated by the driving mechanism, and the position of the flow (gas) including raw material gas entering and exiting the rotor adsorber is fixed, and the cycle operation of adsorption and desorption is different. Simultaneously carried out in each adsorption fan-shaped chamber in the adsorber, which makes up for the shortcomings of the classic moving bed adsorption process that the adsorbent is easy to lose and cannot be applied to the PSA separation or purification process. At the same time, compared with the traditional fixed bed PSA process, it is larger. The amount of adsorbent loading is greatly reduced, the adsorption efficiency is improved, the product gas purity is high and the yield is high, and the technical bottleneck of fixed bed PSA purity and yield is inversely proportional

However, the RWPSA process also has obvious limitations and disadvantages: First, the diameter and height (thickness) of the adsorption wheel are relatively limited, resulting in an insufficient scale of adsorption treatment. This is because RWPSA is essentially a moving bed, and similar circulation For "steady state" mass transfer in these typical moving bed adsorption processes, such as bed or fluidized bed, the axial mass transfer diffusion or radial mass transfer diffusion capacity must be limited

The idea of ​​the present invention is disclosed that "more gas flows through the adsorption tower, and there are more in-out combinations, and the cycle process of adsorption and analysis can be composed of more steps", etc., but none of them can overcome the inherent defects of the SMB process. Especially in the field of gas PSA, the typical SMB process is almost difficult to use

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