CN1100588C - Pressure swing adsorption process for extracting carbon monooxide as fuel from blast furnace waste gas - Google Patents

Abstract

The present invention relates to a two-stage pressure swing adsorption process for separating concentrated carbon monoxide from gas mixtures, especially blast furnace gas. It aims to solve the problem of extracting CO as fuel from blast furnace gas. In the pressure swing adsorption method, each adsorption bed in the first stage of the process goes through the steps of adsorption, pressure equalization drop, reverse discharge, flushing, pressure equalization increase, and final pressure increase to absorb and remove carbon monoxide in the mixed gas. After the components are separated, each adsorption bed in the second stage of the process will go through the steps of adsorption, pressure equalization, parallel release, evacuation, pressure equalization, and final pressure increase to remove components weaker in adsorption than carbon monoxide. Concentrates carbon monoxide.

Description

Pressure Swing Adsorption for Concentrating Carbon Monoxide from Blast Furnace Gas

The invention relates to a pressure swing adsorption process for separating and purifying gas from a gas mixture, in particular to a two-stage pressure swing adsorption process for separating and extracting carbon monoxide from blast furnace gas produced in the smelting process of a steel plant.

Pressure swing adsorption is a technique for separating and purifying gases from gas mixtures. It is a gas-solid phase physical adsorption process carried out at room temperature. Pressure swing adsorption technology is also a technology with low energy consumption and no environmental pollution. Pressure swing adsorption technology is based on the characteristics that the adsorbent has adsorption selectivity for different gas components, and has a large adsorption capacity for gas components at high pressure (adsorption pressure), but has a small adsorption capacity at low pressure (desorption pressure). , an alternate switching cycle process consisting of adsorption and desorption to achieve the separation of gas components.

The separation and recovery methods of CO generally include cryogenic method, solvent absorption method and adsorption separation method in industry. The cryogenic method is not widely used because of its complicated process and the close boiling point of N2 and CO in the mixed gas, which makes it difficult to separate. The typical solvent absorption method, Cosorb method, was successfully developed by Tenneco Company of the United States in the early 1970s and has been widely used. However, the absorption capacity of the absorption solvent used in the Cosorb method will decrease after long-term contact with impurities such as water, hydrogen sulfide, and nitrogen in the mixed gas containing CO. Therefore, the pretreatment process of Cosorb method is complicated, and the energy consumption of absorbent regeneration is high. Adsorption separation technology has been adopted in industry in the late 1950s, and is now widely used in the separation and purification of H ₂ , N ₂ , O ₂ , CH ₄ and other gases, as well as the purification of other industrial gases.

The existing adsorption separation method has different process steps according to the difference of raw material gas. Among them, in the existing two-stage pressure swing adsorption purification CO process, each adsorption bed is sequentially adsorbed in the first stage of the adsorption process, and the cycle steps of equalizing pressure drop, reverse discharge, washing, equalizing pressure rise, and finally boosting are firstly removed. H ₂ O, CO ₂ and other components with stronger adsorption capacity than CO; then enter the second stage of adsorption process, each adsorption bed sequentially undergoes the cycle steps of adsorption, replacement, reverse discharge, vacuum pumping, and boosting to carry out CO and N ₂ Separation of components such as , O ₂ , H ₂ , removing components with weaker adsorption than carbon monoxide, absorbing and extracting carbon monoxide, and obtaining _CO products. The existing two-stage pressure swing adsorption method for extracting CO has a high degree of purification, but the process steps are complicated, the operation is complicated, and the equipment investment is high.

During the smelting process of iron and steel plants, a large amount of blast furnace gas is produced. Its composition is:

Composition: CO H ₂ CO N ₂ O ₂ +Ar

V%: 22～25 2～5 8～22 50～60 0.1

The calorific value of blast furnace gas with this content is very low, only about 750 kcal/Nm ³ , so it cannot be used as fuel, and most of it can only be recovered as waste heat. The gas that cannot be recovered has to be discharged into the atmosphere. The amount of CO discharged into the atmosphere every year reaches 5.6 million tons Above, not only caused serious pollution to the environment but also wasted CO valuable energy. The existing blast furnace gas cannot be reused because the CO concentration in the blast furnace gas is too low. Therefore, increasing the CO concentration of the blast furnace gas also increases the calorific value of the blast furnace gas, which can be recycled and reused as fuel or other It is of great significance to the protection of the environment and the comprehensive utilization of CO. As a fuel, high-purity CO is not required, so a simpler process can be used.

In view of this, the purpose of the present invention is to provide a pressure swing adsorption method for enriching carbon monoxide from blast furnace gas with relatively simple process, convenient operation and low investment; another purpose of the present invention is to provide a method for producing ～85%, the pressure swing adsorption method of enriching carbon monoxide from the blast furnace gas of the fuel gas whose combustion calorific value is ^more than 2000kcal/Nm; Another purpose of the present invention is to make the CO content in the exhaust gas drop to as low as possible, reduce the environment Contaminated pressure swing adsorption for carbon monoxide enrichment from blast furnace gas.

The purpose of the present invention is achieved in this way: on the basis of the existing pressure swing adsorption two-stage method for purifying CO, in its second stage of operation PSA-II, the step of parallel release is directly released to normal pressure, and the Replacement and reverse steps. Therefore, the process steps of the process are simplified, and the investment of the device is greatly reduced.

The pressure swing adsorption method (referring to accompanying drawing) of enriching carbon monoxide from the blast furnace gas of the present invention, in the first section operation (PSA-I) and the second section operation (PSA-II) that have at least two adsorption beds respectively In the pressure swing adsorption system composed of serial connections, the adsorbent filled in the adsorption bed is used to selectively adsorb and separate the impurity gas in the mixed gas. The steps of pressure drop, reverse discharge, flushing, pressure equalization, and final pressure increase, after absorbing and removing components with stronger adsorption than carbon monoxide in the mixed gas, and then through the second stage of the process, each adsorption bed circulates and undergoes the adsorption process in turn. , equalizing pressure drop, parallel release, evacuation, equalizing pressure increase, and finally boosting the steps to remove components that are weaker in adsorption than carbon monoxide, absorb and extract carbon monoxide.

The gas used in the flushing step of the first stage of the above-mentioned process comes from the waste gas discharged from the second stage of the process.

The adsorbent in the adsorption bed of the above-mentioned first stage process is at least one of silica gel, activated carbon, aluminum glue, and carbon molecular sieve, and the adsorbent in the adsorption bed of the second stage process is activated carbon, carbon molecular sieve, and zeolite molecular sieve. at least one.

The pressure of the adsorption step of the first stage of the process is 0.1-1.2 MPa, the pressure of the adsorption step of the second stage of the process is 0.1-1.1 MPa, and the pressure of the vacuuming step is -0.07--0.098 MPa.

The pressure swing adsorption method (referring to accompanying drawing) of enriching carbon monoxide from carbon monoxide mixed gas of the present invention, constitutes the pressure swing adsorption system by the serial connection of the first stage procedure (PSA-I) and the second stage procedure (PSA-II), The CO concentration process is as follows.

The blast furnace gas is introduced from the outside of the system, and enters the adsorption bed of the first stage of the process through the pipeline at a pressure of 0.1-1.2MPa (gauge pressure) and a room temperature of 20-40°C. The first stage of the process depends on the composition, gas volume and pressure of the raw material gas. It consists of three or more adsorption beds (3 to 10), and is equipped with corresponding program control valves according to the number of adsorption beds and process steps. The adsorbent filled in each adsorption bed is one or more of special silica gel, activated carbon, aluminum gel, and carbon molecular sieve to remove H ₂ O, CO ₂ and sulfide. The obtained semi-product gas contains N ₂ and a small amount of H ₂ and O ₂ + Ar, and enters the adsorption bed in the second stage of the process. Components such as _CO2 adsorbed in the adsorption bed in the first stage of the process are desorbed by reverse discharge and flushing, and the flushing gas comes from the parallel release of the waste gas in the second stage.

The first stage of the process aims to remove components with stronger adsorption than CO. Each adsorption bed completes a cycle operation, which needs to go through the steps of adsorption, pressure equalization drop, reverse pressure release, flushing, pressure equalization increase, and final pressure increase. Each adsorption bed alternately completes the above process steps. Each adsorption bed is performing different steps at the same time. At any time, there is always one or more adsorption beds in the adsorption step, and under the condition that the pressure is basically constant, the obtained semi-product gas is passed through the pipeline. It is sent to the adsorption bed of the second stage of the process. Each step of this process will be described below.

Adsorption (A): The raw material gas enters the adsorption bed continuously and stably under a certain pressure (0.1-2.0MPa gauge pressure), and the H ₂ O, CO ₂ , sulfide, etc. The adsorbed CO, H ₂ , O ₂ , N ₂ , Ar, etc. flow out of the adsorption bed to the second stage of process to separate CO from other components. After the adsorption bed has absorbed impurities for a period of time, the adsorbent is basically saturated by impurities such as CO ₂ and H ₂ , and the next step is required to regenerate the adsorbent.

Equalizing pressure drop (ED): The equalizing pressure drop step is a process in which the adsorption bed that has completed the adsorption step releases pressure to other adsorption beds that need to be boosted. The equalizing pressure drop step can recover useful components in the adsorption bed. The step of equalizing pressure drop can be divided into 1 to 5 times, which are referred to as one-time equalizing pressure drop, second-time equalizing pressure drop, three-time equalizing pressure drop, four-time equalizing pressure drop, and five times equalizing pressure drop. In the specific process, the number of equal pressure drops used depends on the pressure and composition of the feed gas and the number of adsorption beds.

Reverse release (D): that is, reverse release of pressure. Depressurization is the process of reducing the pressure of the adsorption bed and desorbing the impurity components (components to be removed) adsorbed in the adsorption bed. Reverse depressurization means that the flow direction of the gas flow is opposite to that of the raw material gas flow.

Flushing (P): Flushing is the process of purging the adsorption bed with gas without impurity components to fully desorb the impurity components. The flushing gas comes from the exhaust gas of the second stage of the process.

Equal pressure rise (ER): Equal pressure rise is the process of increasing the pressure of the adsorption bed by using the equal pressure drop gas of another tower. The steps of equalizing pressure can be divided into 1 to 5 times, which are called one-time equalizing, second-time equalizing, three-time equalizing, four-time equalizing and five-time equalizing. In the specific process, the number of equal pressure rises used depends on the pressure and composition of the raw material gas. The average pressure rise corresponds to the number of average pressure drops.

Final boost (FR): This step is the process of raising the pressure of the adsorption bed to the adsorption pressure.

After the above steps are completed, the adsorption bed has completed a cycle of cycle operation. The process steps experienced by each adsorption bed are exactly the same, but they are staggered in time to ensure that one adsorption tower is performing the adsorption step operation at any time, so that Ensure continuous operation of the device.

The second process is connected in series after the first process. It consists of four or more adsorption beds (4 to 12) according to the composition, gas volume and pressure of the feed gas, and is equipped with corresponding program control valves according to the number of adsorption beds and process steps. The adsorption bed is filled with activated carbon, molecular sieve or carbon molecular sieve adsorbent, depending on the blast furnace gas composition may be one or more of them. In the adsorption bed of the second stage, the adsorbent selectively adsorbs CO, and the CO stays in the adsorption bed, and other H ₂ , N ₂ , O ₂ , Ar are discharged from the outlet and returned to the first stage through the pipeline. , as the flushing gas for the regeneration of the adsorbent in the first stage of the process, the gas after flushing is vented, which is mainly H ₂ +N ₂ +CO ₂ . The CO occluded in the adsorption bed is desorbed by vacuum suction to obtain a concentrated CO product with a CO concentration greater than 66% (equivalent to 2000kcal/Nm ³ ) and output to the user as fuel or other purposes.

In the first stage of the process to obtain CO products, in each cycle of the second stage of the process, each adsorption bed has to go through the process steps of adsorption, pressure equalization, parallel discharge, evacuation, and boosting pressure, no matter how many combinations of adsorption beds are used , these process steps are alternately performed to make the continuous and stable output of CO products. Each step is described as follows:

Adsorption (A): The semi-finished gas output from the first stage of the process (PSA-I) is sent to this section as the raw material gas of (PSA-2), and enters from the inlet end of the adsorption bed, in which CO is selectively adsorbed on the adsorbent Above, other components are discharged from the top of the adsorber to the PSA-I process as adsorption waste gas. Part of it is used as flushing gas for adsorbent regeneration in PSA-I process. This step achieves the separation of CO and other less adsorbable components.

Equal pressure drop (ED): This step is the same as the equal pressure drop step

Parallel release (PP): that is, forward pressure release. The pressure is reduced to normal pressure along the direction of adsorption, the depressurized gas flows into the adsorption waste gas, and is discharged out of the system through the first stage of the process.

Evacuation (VC): When the pressure of the adsorption bed drops to normal pressure, the pressure of the adsorption bed is further reduced by the power of the vacuum pump, and the extracted gas is the concentrated CO product, which is output to the system for users. After this step is completed, the adsorbent in the adsorption bed is also regenerated, ready for the next cycle operation.

Final Boost (FR): After the evacuation step is complete, the bed is pressurized with adsorption waste gas.

The pressure swing adsorption method for enriching carbon monoxide from blast furnace gas of the present invention uses blast furnace gas as a raw material, adopts the first stage process to remove _H2O , _CO2 and other components whose adsorption force is stronger than CO, and the second stage process removes the adsorbed Components such as N ₂ , O ₂ , and H ₂ , which are weaker than CO, are absorbed by CO, and then concentrated CO products are obtained by depressurization and evacuation. Compared with the existing two-stage method, the replacement and reverse pressure release steps are eliminated, and the process is simpler, the operation steps are simplified, and the investment of the device is greatly reduced.

The invention can use blast furnace gas as a raw material to prepare CO fuel with a CO content of 66-85% and a combustion calorific value above 2000kcal/Nm ³ . The CO content in the exhaust gas is extremely low, and the content is below 9%, thereby reducing environmental pollution.

Below, the present invention will be further described with embodiments and accompanying drawings.

Brief description of the attached drawings.

Fig. 1 is a process flow diagram of a pressure swing adsorption method for enriching carbon monoxide from blast furnace gas of the present invention. It shows the process flow of three-bed process in the first stage and four-bed process in the second stage.

Fig. 2 is a gas flow diagram of each step in the first stage of the process in Fig. 1 .

Fig. 3 is a gas flow diagram of each step in the second stage of the process in Fig. 1 .

Fig. 4 is a trend diagram of pressure changes in each step of the first stage of the process in Fig. 1 .

Fig. 5 is a trend diagram of pressure changes in each step of the second stage of the process in Fig. 1 .

Fig. 6 is a process flow diagram of another pressure swing adsorption method for enriching carbon monoxide from blast furnace gas according to the present invention. It shows the process flow of six-bed process in the first stage and eight-bed process in the second stage.

FIG. 7 is a gas flow diagram of each step in the first stage of the process in FIG. 6 .

FIG. 8 is a gas flow diagram of each step in the second stage of the process in FIG. 6 .

Example 1

A kind of pressure swing adsorption method of enriching carbon monoxide from blast furnace gas of the present invention, raw material gas is blast furnace gas, and its composition:

Composition: CO ₂ O ₂ CO H ₂ N ₂

V%: 20.61 0.3 22.76 1.46 54.87

This pressure swing adsorption method adopts a common pressure swing adsorption system, and the process flow is shown in Figure 1. The first stage of process PSA-I adopts a three-bed and one uniform process, and the second stage of process PSA-II adopts a four-bed and one uniform process. . The corresponding relationship between the adsorption bed process steps of the first stage process and the second stage process is shown in Table 1 and Table 2 respectively. The gas flow direction of the process steps of the first stage process and the second stage process is shown in Figure 2 and Figure 3 respectively. In the figure, only the gas flow direction of each step of the A bed is marked, and the gas flow direction between the other beds is similar to that of the A bed. Therefore not marked.

The operating pressure of the first stage of the process is 0.1 ~ 0.35MPa, and the operating pressure of the second stage is within the range of -0.08 ~ 0.3MPa. The pressure changes in each step are shown in Fig. 4 and Fig. 5 respectively.

The first section of process PSA-I has three adsorption beds IA, IB, and IC of tower structure, and the raw material gas pipe 1I communicated with each adsorption bed and the respective inlet valves are 1-IA, 1-IB, and 1-IC; The semi-finished pipe 2I communicated with each adsorption bed, and the respective outlet valves 2-IA, 2-IB, 2-IC; the reverse discharge pipe 3I communicated with each adsorption bed, and the respective reverse discharge valves 3-IA, 3- IB, 3-IC; the pressure equalizing final riser pipe 5I and its regulating valve 5-1 communicated with each adsorption bed, and the respective pressure equalization final riser valves 5-IA, 5-IB, 5-IC; and each adsorption bed Connected flushing pipe 6I and its regulating valve 6-I, and respective flushing valves 6-IA, 6-IB, 6-IC. The adsorbent filled in each adsorption bed is silica gel or activated carbon.

The second section of process PSA-II has four tower-structured adsorption beds IIA, IIB, IIC, and IID, which are connected to the semi-finished pipe 1I of the first section of the process PSA-I and are connected to the semi-finished pipe III of each adsorption bed in this process and Its regulating valve 1-II, and the respective inlet valves 1-IIA, 1-IIB, 1-IIC, 1-IID; the adsorption waste gas pipe 2II communicated with each adsorption bed, and the respective discharge valves 2-IIA, 2- IIB, 2-IIC, 2-IID 2-2D; product pipe 3II communicated with each adsorption bed, and respective outlet valves 3-IIA, 3-IIB, 3-IIC, 3-IID; communicated with each adsorption bed Parallel discharge pipe 4II, and respective parallel discharge valves 4-IIA, 4-IIB, 4-IIC, 4-IID; the equalizing final booster pipe 5II and its regulating valve 5-II communicated with each adsorption bed, and respective The pressure equalizing final boost valves 5-IIA, 5-IIB, 5-IIC, 5-IID; the product pipe 3II is provided with a vacuum pump 7. The adsorbent filled in each adsorption tower is zeolite molecular sieve.

The pressure swing adsorption system, under the instruction of the computer, automatically switches and executes the work steps set according to the process requirements by the valves matched with the process.

Blast furnace gas enters the first section of process PSA-I of the present invention under a pressure of about 0.35 MPa. According to the working steps in Table 1, the process adsorption bed is composed of adsorption A, pressure drop ED, reverse discharge D, and flushing in each cycle. It consists of six steps: P, pressure equalization ER, and final boost FR. In the three-bed adsorption, impurity gases such as H ₂ O, CO ₂ and other strongly adsorbed components in the gas are removed, and the semi-finished product is sent to the second stage of the process PSA-II of the present invention. The adsorption bed that enters the second process under the pressure of 0.3MPa is operated in a continuous cycle according to the working steps in Table 2. Each cycle of the process adsorption bed is composed of adsorption A, equal pressure drop ED, parallel release of PP, evacuation of VC, and equal pressure rise. ER, the final step-up FR consists of six steps. To remove most of the weakly adsorbed impurity components N ₂ , H ₂ , Ar+O ₂ , etc. in the semi-product gas, and finally obtain concentrated CO products from the solid-phase adsorbent in the adsorption bed by evacuation. When the system is running, under the control of the computer, the blast furnace gas is continuously input, and the concentrated product CO is continuously output.

In this embodiment, the product CO purity ≥ 66% can be obtained, that is, the combustion calorific value is more than 2000kcal/Nm ³ , and the CO recovery rate is more than 85%, becoming an available industrial fuel. The CO in the exhaust gas is reduced from 22 to 25% to less than 8%.

Example 2:

Another pressure swing adsorption method for enriching carbon monoxide from blast furnace gas of the present invention is similar to Example 1, the first section of process PSA-I is a six-bed one-homogeneous process, and the second section of process PSA-II is eight beds Uniform craftsmanship. At any time, two adsorption beds are in the feed adsorption state at the same time, and the process flow is shown in Figure 6.

Raw material gas is steel plant blast furnace gas, and its composition is the same as embodiment 1:

Composition: CO ₂ O ₂ CO H ₂ N ₂

V%: 20.61 0.3 22.76 1.46 54.87

This pressure swing adsorption method adopts a common pressure swing adsorption system, and the process flow is shown in Figure 1. The first stage of process PSA-I adopts a six-bed one-homogeneous process, and the second stage of the process PSA-II adopts an eight-bed one-homogeneous process. . The corresponding relationship between the adsorption bed process steps of the first stage process and the second stage process is shown in Table 3 and Table 4 respectively. The gas flow direction of the process steps of the first stage process and the second stage process is shown in Figure 7 and Figure 8 respectively. In the figure, only the gas flow direction of each step of the A bed is marked, and the gas flow direction between the other beds is similar to that of the A bed. Therefore not marked.

The operating pressure of the first stage of the process is 0.1 ~ 0.35MPa, and the operating pressure of the second stage is within the range of -0.08 ~ 0.3MPa. The pressure changes in each step are shown in Fig. 4 and Fig. 5 respectively.

The first section of process PSA-I has six tower-type adsorption beds IA, IB, IC, ID, IE, IF, the feed gas pipe 1I connected with each adsorption bed, and the respective inlet valves are 1-IA, 1 -IB, 1-IC, 1-ID, 1-IE, 1-IF; semi-finished pipe 2I communicating with each adsorption bed, and respective outlet valves 2-IA, 2-IB, 2-IC, 2-ID, 2-IB, 2-IF; the reverse discharge pipe 3I communicating with each adsorption bed, and the respective reverse discharge valves 3-IA, 3-IB, 3-IC, 3-ID, 3-IE, 3-IF; and The pressure equalizing final riser pipe 5I connected to each adsorption bed and its regulating valve 5-I, and the respective pressure equalizing final riser valves 5-IA, 5-IB, 5-IC, 5-ID, 5-IE, 5-IF ; Flushing pipe 6I and its regulating valve 6-I communicating with each adsorption bed, and respective flushing valves 6-IA, 6-IB, 6-IC, 6-ID, 6-IE, 6-IF.

The second process, PSA-II, has eight tower-type adsorption beds IIA, IIB, IIC, IID, IIE, IIF, IIG, IIH, which are continuous with the semi-finished tube 1I of the first process PSA-I, and are separated from this process. The semi-finished pipe 1II connected to the adsorption bed and its regulating valve 1-II, and the respective inlet valves 1-IIA, 1-IIB, 1-IIC, 1-IID, 1-IIE, 1-IIF, 1-IIG, 1- IIH; Adsorption waste gas pipe 2II communicated with each adsorption bed, and respective discharge valves 2-IIA, 2-IIB, 2-IIC, 2-IID, 2-IIE, 2-IIF, 2-IIG, 2-II; The product pipe 3II that is communicated with each adsorption bed, and respective outlet valves 3-IIA, 3-IIB, 3-IIC, 3-IID, 3-IIE, 3-IIF, 3-IIG, 3-IIH; The parallel discharge pipe 4II that the bed is connected, and the respective parallel discharge valves 4-IIA, 4-IIB, 4-IIC, 4-IID, 4-IIE, 4-IIF, 4-IIG, 4-IIH; and each adsorption bed Connected pressure equalizing final booster pipe 5II and its regulating valve 5-II, and respective pressure equalizing final booster valves 5-IIA, 5-IIB, 5-IIC, 5-IID, 5-IIE, 5-IIF, 5-IIG, 5-IIH; a vacuum pump 7 is arranged in the product pipe 3II.

The pressure swing adsorption system, under the instruction of the computer, automatically switches and executes the work steps set according to the process requirements by the valves matched with the process.

The raw material gas is compressed to 0.5MPa, and enters the PSA-I process at room temperature. After removing impurities such as CO ₂ , H ₂ O, and sulfide; the semi-finished gas enters the PSA-II process, and H ₂ , N ₂ and CO are separated. Concentrate CO. The concentrated CO is obtained by vacuuming, and the adsorbent is regenerated at the same time.

The PSA-I process operates according to the process steps of six beds and one equalization shown in Chart 3. The adsorption bed in this process consists of adsorption A, pressure equalization drop ED, reverse discharge D, flushing P, pressure equalization rise ER, and final pressure boost in each cycle. FR consists of six steps. Fig. 7 takes adsorption bed IA as an example to show the gas flow direction of each working step, and the gas flow direction between other adsorption beds is similar to that of bed A, so no other description is given.

In operation, there are always two adsorption beds in the adsorption step of feeding and producing semi-product gas, and the other four adsorption beds are in different steps of adsorption regeneration. According to the working steps in Table 3, the semi-product gas can be continuously and stably transported to the PSA-II process as the raw material gas for the PSA-II process. The adsorbents filled in each adsorption bed in this process are activated alumina and silica gel. The cycle period experienced was about 720 seconds. The adsorption pressure is 0.5MPa. The regeneration of the adsorbent is accomplished through the equalization pressure drop, the final pressure of the equalization pressure is ~0.25MPa and then reversed to normal pressure, and then the washing step is completed under normal pressure.

The PSA-II process operates according to the process steps in Table 4. Each cycle of the adsorption bed in this process consists of six steps: adsorption A, equal pressure drop ED, parallel discharge PP, evacuation VC, equal pressure increase ER, and final pressure increase FR. Figure 8 uses the adsorption bed IIA as an example to illustrate the gas flow direction of each working step, and the gas flow direction between other beds is similar to that of bed A, so no additional description is given.

During operation, there are always two adsorption bed feeds in the adsorption step, and the adsorption step is carried out at a pressure of 0.4MPa to remove weakly adsorbed impurity components N ₂ , H ₂ , part of CH ₄ and Ar, etc. in the semi-product gas. After the adsorption is completed, the pressure is equalized with another adsorption bed that has just been evacuated. The final pressure equalization is about 0.18MPa (gauge pressure). After equalizing the pressure drop, carry out the parallel discharge step, and the pressure of the final adsorption bed dropped to normal pressure 0 MPa (gauge pressure), so that the gas at the front end of the adsorption is further separated. Finally, the evacuation pressure reduction method is adopted, and the evacuation pressure is about 0-0.08MPa to obtain concentrated CO products, and the adsorbent can be regenerated at the same time. Then the adsorption bed is raised to ~0.118MPa in the way of pressure equalization, and then the adsorption waste gas is used to raise the pressure to the adsorption pressure of 0.4MPa to carry out the operation of the next cycle. The eight adsorption beds are filled with zeolite molecular sieves as adsorbents. The cycle experienced is approximately 960 seconds.

This example can obtain product concentrated CO purity > 75%, CO recovery > 80%. The CO in the exhaust gas is reduced from 22 to 25% to less than 9%.

Table 1 Correspondence diagram of three-bed process steps in PSA-I process 1 2 3 4 5 6 7 8 9 10 11 12 IA A ED D. P ER FR IB ER FR A ED D. P IC ED D. P ER FR A

Table 2 Corresponding relationship of four-bed process steps in PSA-II process 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 IIA A ED PP VC ER FR IIB ER FR A ED PP VC IIC VC ER FR A ED PP IID ED PP VC ER FR A

Table 3 Correspondence diagram of six-bed process steps in PSA-I process 1 2 3 4 5 6 7 8 9 10 11 12 IA A ED D. P ER FR IB FR A ED D. P ER FR IC ER FR A ED D. P ID P ER FR A ED D. IE ED D. P ER FR A IF A ED D. P ER FR A

Table 4 Corresponding relationship diagram of the eight-bed process steps in the PSA-II process 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 IIA A ED PP VC ER FR IIB FR A ED PP VC ER FR IIC ER FR A ED PP VC IID VC ER FR A ED PP VC IIE VC ER FR A ED PP IIF PP VC ER FR A ED PP IIG ED PP VC ER FR A IIH A ED PP VC ER FR A

Claims (4)

1. The pressure swing adsorption method for enriching carbon monoxide from blast furnace gas, in the pressure swing adsorption method consisting of the first stage process (PSA-I) and the second stage process (PSA-II) connected in series with at least two adsorption beds respectively. In the adsorption system, the adsorbent filled in the adsorption bed is used to selectively adsorb and separate the impurity gas in the mixed gas. In the steps of flushing, pressure equalization, and final pressure increase, after absorbing and removing the components in the mixed gas that are more adsorbable than carbon monoxide, the adsorption beds in the second stage are cycled through successively including adsorption, pressure equalization drop, and sequential operation. The steps of release, evacuation, pressure equalization, and final pressure increase are to remove components that are weaker in adsorption than carbon monoxide, and absorb and extract carbon monoxide. 2. The pressure swing adsorption method according to claim 1, characterized in that the gas used in the flushing step of the first stage of the process comes from the waste gas discharged from the second stage of the process. 3. The pressure swing adsorption method according to claim 1 or 2, wherein the adsorbent in the adsorption bed of said first stage of the feature is at least one of silica gel, activated carbon, aluminum glue, and carbon molecular sieve, and the second The adsorbent in the adsorption bed of the first step is at least one of activated carbon, carbon molecular sieve and zeolite molecular sieve. 4. The pressure swing adsorption method according to claim 3, characterized in that the pressure of the adsorption step of the first stage process is 0.1-1.2 MPa, and the pressure of the adsorption step of the second stage process is 0.1-1.1 MPa, The pressure in the vacuuming step is -0.07～-0.098MPa.

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