KR970004281B1 - Circulated air filtering system for eliminating chemical agent - Google Patents

Abstract

A air filtering system is composed of two adsorbing layers(1,2) where an adsorbent that adsorbs selectively a poisonous gas from air is filled, a conduit(3) connecting these and four solenoid valves(S1,S2,S3,S4), and four check valves(C1,C2,C3,C4) and two flow rate control valves. And the conduit is equipped with an entrance pipe flowing in the polluted air, an exhaust pipe exhausting refined filtering air filtered in an adsorption step, and an exit pipe exhausting the desorbed gas of polluted air through an adsorption/desorption procedure by decompressing it with atmospheric pressure.

Description

Circulating air filtration system for chemical agent removal

1 is a schematic diagram showing a configuration form of an example of the present invention

2 is an air flow chart showing the step-by-step operating process of the present invention.

* Description of the symbols for the main parts of the drawings *

1,2: adsorption layer 3: conduit

4: Pressure gauge S1, S2, S3, S4: Solenoid valve

C1, C2, C3, C4: Check valve V1, V2: Flow control valve

The present invention relates to a circulating air filtration system for removing a renewable chemical reaction using a pressure conversion adsorption method and a circulating filtration method of a chemical agent using the same.

In the current NBC collective protection system, a gas filter that adsorbs, removes toxic gases from polluted air, and supplies purified air is a fixed bed filter filled with activated carbon in a drum, a panel, or a cartridge having a radial flow. Adopts a simple adsorption method that discards at the end of its service life.

However, these gas filters have excellent filtration performance but have various disadvantages such as limited lifetime, indeterminate remaining life, risk of exposure to toxic gas when the filter is replaced, and disposal of used filters.

In addition, high molecular weight chemical agents such as Sarin (GB), Soman (GD), and Mustard (HD) are well adsorbed on adsorbents of large processing size, such as activated carbon or polymer resins, and have low molecular weight chemicals such as cyanide. Hydrogen (AC) and cyanide chloride (CK) adsorb well on molecular sieves. This physical adsorption proceeds very quickly, whether strong or weak, but the adsorption of strongly adsorbed components is very slow, while the weakly adsorbed components desorb very quickly. Despite these adsorption characteristics, the technical development of the CBR method has been limited to the development of an adsorbent for removing a larger amount of chemical agent using a limited amount of adsorbent, that is, to extend the filtration life. The emphasis has been on the treatment of metals and chemicals in order to remove low molecular weight chemical agents that have weak adsorption forces, that is, the breakdown of the adsorption layer occurs quickly. Thus, it was not possible to extend the filter life for a wide range of chemical agents.

In order to solve this problem, the present inventors have introduced a pressure change adsorption method using various valves in a filtration system in a chemical action of removing toxic components from air contaminated with a chemical agent and supplying filtered air to a collective protection facility. By alternately performing the adsorption and desorption process, the polluted air is purged and the used adsorbent can be recycled directly in the filter to be reused. Therefore, the filter can be recycled without moving. The economic burden and risks involved in disposal were solved. As the adsorption and desorption processes are circulated in the adsorbent and the adsorbent is reused in the filter, the filtration life can be extended for various chemical agents regardless of the adsorption characteristics and types of chemical agents.

An object of the present invention is a plurality of adsorption layer filled with the adsorbent, each having two branches on each side of each of the adsorption layer, the outlet pipe for filtration air connecting the two branches on one side, the desorption gas on each branch on the other axis Solenoid valves provided on the left and right sides of the outlet pipe for the contaminated air and the inlet pipe for the contaminated air, check valves installed on the left and right sides of the outlet pipe for the filtered air, and flow control valves respectively installed above the two conduits above the outlet pipe for the filtered air. It is to provide a circulating air filtration system for the chemical agent removal consisting of.

In addition, another object of the present invention is to use the circulating air filtration system to alternately repeat the adsorption and desorption process in one circulation cycle according to the pressure conversion to remove the toxic components from the air contaminated by the chemical agent. It is to provide a circulating filtration method of a chemical agent consisting of adsorption removal and continuous supply of filtered purge air.

(a) Adsorption step of introducing high pressure contaminated air into the adsorption bed to adsorb and remove toxic components and exhaust the filtered air to the outlet.

(b) a pressure reduction / cleaning step of cleaning a portion of the filtration air exhausted from several other adsorption layers desorbed from the adsorption layer by depressurizing the pressure of the adsorption layer to atmospheric pressure and desorbed to the inlet of the adsorption layer,

(c) a pressurizing step of pressurizing the adsorption layer using filtered air.

In the present invention, the pressure change adsorption method is performed by alternately performing a high pressure adsorption step and a desorption step under a lower pressure using various valves, and at the same time performing the process of separating chemical agents and regenerating the adsorbent. Can be.

That is, using an air compressor, the mixed gas containing the component to be separated and the component to be removed first is subjected to a high pressure, and the solenoid valve is introduced into the adsorption layer filled with the adsorbent to selectively adsorb and purify the component to be removed. The discharged component is evacuated through the check valve and the flow control valve. Next, the pressure of the adsorption layer, which has undergone the adsorption process for a certain period of time, is opened to reduce the atmospheric pressure by opening another solenoid valve to desorb the adsorbed component, and then use a part of the purified component as a cleaning gas through another flow control valve and check valve. The used adsorbent is regenerated by pushing out of the adsorption layer. In this way, by alternately performing the adsorption / desorption process by the pressure change it is possible to regenerate / reuse the adsorbent. In order to perform this process continuously, at least two adsorption beds are required.

The basic principle of the above-described pressure conversion adsorption method will be described in more detail by applying to a circulating air filtration system using two adsorption beds as an example of the present invention.

In the circulating air filtration system of the present invention, each of the following step-by-step processes may be performed in a circulation cycle by using the solenoid valve, the check valve, and the flow control valve provided in the present invention.

I. Adsorption stage

II. Counter-current decompression / counter-current cleaning steps

III. Countercurrent pressurization by filtered air

The step-by-step process is carried out by two adsorption layers alternately as shown in the following table. While one adsorption layer performs the adsorption step, the other adsorption layer is divided into 1/2 cycles to carry out the depressurization, cleaning and pressurization steps in order to continuously filter the air. To recover.

Table

For example, the configuration and each step of the circulation air filtration system of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows a system consisting of two adsorption layers in the circulating air filtration system of the present invention. Specifically, two adsorption layers (1, 2) filled with an adsorbent capable of selectively adsorbing toxic gases in the air are illustrated in FIG. ), The conduits (3) connecting them, four solenoid valves (S1, S2, S3, S4), four check valves (C1, C2, C3, C4) and two flow control valves (V1, V2). Consists of. The conduit is provided with an inlet pipe for introducing contaminated air, an exhaust pipe for exhausting the filtered filtered air filtered through the adsorption step, and an outlet pipe for evacuating the desorbed gas of the contaminated air that has undergone the adsorption / desorption process to atmospheric pressure. The solenoid valve can be connected to a programmable microprocessor to allow the microprocessor to be opened and closed automatically. In addition, a pressure gauge 3 is attached to the conduit through which the polluted air flows through the solenoid valve so as to confirm that the pressure of the polluted air is maintained at an appropriate level.

FIG. 2 schematically illustrates a flow of air through the operation process during one cycle of each step according to an embodiment of the present invention. The performance of each step may be divided into four steps of adsorption-pressurization process, pressure-reduction / cleaning-adsorption process, pressure-adsorption process, and pressure-adsorption process for the adsorption layer (1) -adsorption layer (2).

First step: adsorption layer (1)-adsorption step, adsorption layer (2)-pressure reduction / cleaning step

The contaminated air is pressurized using an air compressor and then introduced into the adsorption bed 1 through the solenoid valve S1. Toxic gas is adsorbed and removed by the filled activated carbon, and only the filtered air is exhausted to the outlet through the flow control valve (V2). A part of the filtered air discharged at this time is depressurized through the flow control valve V1 and introduced into the adsorption layer 2 at a constant flow rate to be used as a cleaning gas. On the other hand, the adsorption layer (2) after the adsorption step for a predetermined time is reduced to atmospheric pressure while the solenoid valve (S4) is opened. At this time, the gas flow in the adsorption layer 2 flows in the opposite direction to the adsorption step. As the pressure in the adsorption layer 2 decreases, the gas of the toxic components adsorbed expands to lower the partial pressure and desorbs from the adsorbent. At the same time as the reduced pressure up to atmospheric pressure, a cleaning step is performed in which the activated carbon is regenerated by pushing the toxic components desorbed by the reduced pressure out of the adsorption layer 2 using the cleaning gas supplied from the adsorption layer 1. In this process, as shown in FIG. 1, the depressurization and washing steps were performed in the opposite direction to the adsorption direction, and the check valve C2 was used to prevent backflow of the desorbed components. In addition, by performing these two steps at the same time to give a little more cleaning time required for the regeneration of the adsorbent, it was possible to reduce unnecessary valve opening and closing.

2nd process: adsorption layer (1)-adsorption step, adsorption layer (2)-pressurization step

Following the first process, the adsorption layer 1 continues the adsorption step and the solenoid valve S4 is closed and the adsorption layer 2 which has completed the decompression / cleaning step flows through the filtered air discharged from the adsorption layer 1. It is introduced through the control valve (V1) and the check valve (C2) to perform a pressurization process up to the adsorption pressure. In the case of cocurrent pressurization using contaminated air in this process, while the pressure in the adsorption layer 2 reaches the adsorption pressure and maintains a uniform pressure throughout the adsorption layer, the flow rate of the contaminated air is increased so that the toxic gas is sufficiently adsorbed by the adsorbent. It cannot be removed. For this reason, destruction of the adsorption layer 2 by the toxic component may easily occur. Therefore, by performing countercurrent pressurization by the above-mentioned process using filtered air, it is possible to suppress the movement of toxic components to the outlet of the adsorption layer and to continuously supply the filtered air exhausted by the circulation of the adsorption layer under pressure without fluctuation of pressure. . The pressurization step was completed within 20 seconds.

Third fixation: adsorption layer (1)-depressurization / washing step, adsorption layer (2)-adsorption step

The contaminated air is introduced into the adsorption layer 2 through the solenoid valve S2 and filtered / exhausted, and the solenoid valve S3 is opened while the adsorption layer 1 completes the adsorption step and performs the depressurization / cleaning step. The cleaning gas in the adsorption layer 1 is supplied through the flow control valve V1 and the check valve C1 in the adsorption layer 2 which is performing the adsorption step. The same process as the first process is performed by the adsorption layers 1 and 2 alternately.

Fourth process: adsorption layer (1) -pressurization step, adsorption layer (2) -adsorption step

Following the third process, the adsorption layer 2 continues the adsorption process, and the solenoid valve S3 is closed while the adsorption layer 1 performs the pressurization step. Pressurized gas is supplied from the adsorption layer 2 from the flow control valve V1 and the check valve C1. The same process as the second process is performed by the adsorption layers 1 and 2 alternately.

The present invention continuously purifies the contaminated air by continuously repeating the above process in one circulation cycle, and the used adsorption layer is recycled and reused through the adsorption / desorption process, so that the filtration life is extended and the risk of replacement and disposal of the filter is increased. This can be solved.

Adsorbents used in accordance with one embodiment of the present invention are conventional activated carbon. Of course, other adsorbents are possible, but activated carbon is preferred for the removal of various chemical agents.

In addition, the adsorption pressure of the adsorption bed is expressed as the pressure of the polluted air compressed by the air compressor, which is preferably 50-60 psig. If it is less than this pressure, the adsorption pressure of the adsorption layer is less than the adsorption layer because the adsorption pressure of the adsorption layer is greater than this range, but the adsorption effect of the adsorption layer is gradually slowed down due to the pressure increase. Increasing pressure beyond the range results in unnecessary operating costs.

According to another embodiment of the present invention, in consideration of the rapid regeneration of the adsorbent used in the cycle consisting of the three steps, it is preferable to limit the cycle time per cycle within 10 minutes.

Another example of the present invention is to perform the washing step in the depressurization / cleaning step at the same time as the pressure of the adsorption layer is reduced to atmospheric pressure. In addition, the washing step is preferably carried out so that a sufficient cleaning effect can be obtained by introducing the cleaning gas into the adsorption layer at a ratio of 1.2 to 1.3 by volume of the cleaning gas to the amount of contaminated air introduced.

One preferred embodiment of the present invention is to perform the pressurization and depressurization / cleaning steps in the opposite direction of the adsorption step using a portion of the filtration air.

On the other hand, the circulating filtration method of the chemical agent according to the present invention is a useful filtration method that can extend the filtration life for a variety of chemical agents in spite of the variety of chemical agents and the degree and extent of their adsorption to the adsorbents. . Examples thereof include large molecular weight and soluble chemical agents such as Sarin (GB) or Soman (GD), and Mustard (HD) and small molecular weight chemicals such as Hydrogen cyanide (AC) and Cyanogen chloride (CK). .

The following examples illustrate the practice of the invention, but are not intended to limit the scope of the invention.

Example 1

In the system configured according to the present invention, 120 parts of the activated charcoal (manufactured by Calgon, USA, particle size: 12-30 mesh) were respectively filled with two adsorption layers of 30 mm in diameter and 300 mm in height, and then DMMP (dimethylmethyl phosphonoate). Contaminated air containing steam is fed to the adsorption bed at a flow rate of 35 l / min under a pressure of 50 psig. DMMP is an analog of Sarin, a nerve agent. It is an organic phosphorus compound with very low vapor pressure and strong adsorption on activated carbon. DMMP vapor content in contaminated air was 0.6 mg / l, and the adsorption body was supplied at a constant concentration through a steam generator. The process shown in FIG. 2 of the accompanying drawings is repeated according to the following presentation time.

1st process-220 seconds, 2nd process-20 seconds

3rd process-220 seconds, 4th process-20 seconds

DMMP vapor is adsorbed and removed by the activated carbon, and 12 L / min of the filtered air is used as the cleaning gas, and the actual recovered filtration air is obtained at a flow rate of 23 L / min. The concentration analysis of the filtered air was performed using a phosphorous gas analyzer that selectively analyzes only organophosphorus compounds, and the reference detection concentration at this time was 0.01 ppm. DMMP vapor in the filtered air was not detected even though the operation was continued for 16,200 minutes, and the amount of DMMP treated during the run time was 0.6 mg / L × 35 L / min × 16,200 min = 340,200 mg, and the amount of recovered filtered air was 23 L /. min x 16,200 min = 372,600.

Comparative Example 1

120 g of activated carbon was packed into an adsorption bed having a diameter of 30 mm and a height of 300 mm, and then a flow rate of 30 l / min was supplied to the adsorption bed under a pressure of 50 psig with contaminated air containing 0.6 mg / l of DMMP vapor. Was destroyed. The amount of DMMP treated during the run time was 0.6 mg / L × 30 L / min × 1875 min = 33,750 mg, and the recovered filtered air amount was 30 L / min × 1875 min = 56,250.

Example 2

80 g of activated carbon was packed into an adsorption layer having a diameter of 30 mm and a height of 300 mm, and then a mixed gas having acetone vapor concentration of 40 mg / L was supplied to the adsorption layer at a flow rate of 7 L / min under a pressure of 50 psig. Unlike Example 1, an experimental apparatus was configured to simulate a process consisting of two adsorption layers using one adsorption layer.

The process shown in FIG. 2 of the accompanying drawings was repeated according to the following presentation time.

1st process-220 seconds, 2nd process-20 seconds

3rd process-220 seconds, 4th process-20 seconds

Acetone vapor was adsorbed and removed by activated charcoal, 2.5 L / min air in the filtered air was used as the cleaning gas, and the remaining 4.5 L / min filtered air was recovered. The concentration analysis of the filtered air was carried out using a hydrocarboncarbon analyzer, and the reference detection concentration at this time was 0.01 ppm. Acetone vapor in the filtered air was not detected even though the operation was continued for 7,320 minutes, and the amount of acetone treated during the running time was 4.0 mg / L × 7 L / min × 7,320 min = 16,470 L.

Comparative Example 2

80 g of activated carbon was packed into an adsorption bed having a diameter of 30 mm and a height of 300 mm, and then a mixed gas having acetone vapor concentration of 40 mg / l was supplied to the adsorption bed at a flow rate of 7 l / min under a pressure of 50 psig. Destroyed in minutes. The amount of acetone treated during the run time was 4.0 mg / L × 7 L / min × 6hr × 60 min = 10,080 mg, and the recovered filtered air amount was 7 L / min × 360 min = 2,520 L.

Experimental results When comparing the filtration life by the method according to the present invention and the conventional adsorption method, about 5 times based on the amount of adsorbate treated using the method according to the present invention, and 3 times based on the amount of filtered air recovered. The above filtration performance improvement was shown.

When the present invention is applied to the chemical agent filtration system, it is possible to extend the filtration life significantly more than the conventional simple adsorption filtration system, and accordingly it is believed that the ripple effect such as improving the economic efficiency and power improvement under the chemical warfare situation, In addition, it is expected to be of great value in gas purification and solvent recovery, which are commercial processes.

Claims (8)

A plurality of adsorption layers (1, 2) filled with an adsorbent, each having two branches on each side of each adsorption layer, the outlet pipe for filtration air connecting the two branches crosswise on one side, desorption gas on each branch on the other side Solenoid valves (S1, S2, S3, S4) respectively provided on the left and right sides of the outlet pipe for the contaminated air and the inlet pipe for the contaminated air, and the check valves (C1, C2, C3, C4) and a circulating air filtration system for chemical agent removal consisting of flow control valves (V1, V2) respectively installed above two conduits above the outlet pipe for filtered air. The circulating air filtration system of claim 1, wherein the adsorbent used is activated carbon. By using the circulating air filtration system of claim 1, the adsorption and desorption process is alternately repeated by performing the following three steps in one circulation cycle according to the pressure conversion, thereby adsorbing and removing toxic components from the air contaminated by the chemical agent and purifying Circulating air filtration of chemical agents characterized by continuous supply of air: (a) adsorption step of introducing high pressure contaminated air into the adsorption bed to adsorb and remove toxic components and exhaust the filtered air to the outlet; (b) a pressure reduction / cleaning step of depressurizing the pressure of the adsorption layer to atmospheric pressure to desorb the adsorbed toxic components to the inlet of the adsorption layer and then cleaning a portion of the filtration air exhausted from the other adsorption layer with the cleaning gas; (c) a pressurizing step of pressurizing the adsorption layer using filtered air. 4. The method of claim 3, wherein the adsorption pressure is 50-60 psig. 4. The circulating filtration method of a chemical agent according to claim 3, wherein the cycle per cycle is performed within 10 minutes. 4. The circulating filtration method of a chemical agent according to claim 3, wherein the washing step in the depressurizing / cleaning step is performed simultaneously with the pressure of the adsorption layer being reduced to atmospheric pressure. 7. The volume ratio of the amount of the cleaning gas to the amount of the contaminated air introduced therein during the cleaning step is 1.2. Circulation filtration method of a chemical agent characterized by being 3. 4. The circulating filtration method of a chemical agent according to claim 3, wherein the pressurizing and depressurizing / cleaning steps are performed in the opposite direction of the adsorption step by filtration air.