JP2005238044A - System for treating basic gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system for efficiently treating a basic substance in basic material-containing gas which is capable of stably reducing the diffusion of the basic gas to environment. <P>SOLUTION: A washing apparatus in which the basic substance in the basic material-containing gas is brought into contact with water, acid or oxide and is treated is combined with a backup apparatus having a mechanism which receives the gas subjected to adsorption treatment discharged from the washing apparatus, permits the adsorption treatment and desorption treatment of the basic gas leaking in the treated gas and permits the conveyance of the treated gas to the washing apparatus. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a system for processing a basic gas such as ammonia or trimethylamine contained in air, and more particularly to a processing system for reducing the basic gas concentration of exhaust gas.

  In recent years, emission concentration regulations for basic substances have been strengthened, and in particular, establishment of a treatment technique for reducing the exhaust gas concentration of specific malodorous substances such as ammonia and trimethylamine is desired. Patent Document 1 describes a method for treating ammonia-containing exhaust gas, which includes a step of bringing exhaust gas containing ammonia into contact with an adsorbent and desorbing ammonia after adsorbing the adsorbent onto the adsorbent. ing.

  Further, as a method for treating exhaust gas containing a large amount of basic gas, chemical cleaning by water cleaning or neutralization shown in FIG. 1 has been used. That is, the gas to be treated is supplied from the lower part of the water washing tower by the transmitter 1, while the washing water is sent from the water storage layer 3 to the water circulation path circulated by the circulation pump 5 by the water supply pump 4, and the upper part of the washing tower. It sprays from the spray nozzle 6 provided in the. The gas to be treated supplied from the lower part of the washing tower is washed with the spray water, and then the gas and mist are separated by the mist separator 2, the gas is discharged from the upper part of the washing tower, and the mist and water are removed from the washing tower. An apparatus has been proposed in which a part of water discharged from the lower part is recycled.

  However, these cleaning devices are simple methods for treating basic gas, but in principle, it is difficult to increase the removal rate beyond a certain limit, and in the case of low-concentration odor, Since the removal rate is particularly lowered, it is often impossible to obtain a high removal rate.

In addition, in order to improve the removal rate of the basic gas, it is necessary to increase the amount of fresh makeup water, and the increase in the amount of makeup water increases the amount of waste water discharged outside the system after removing the basic gas. As a result, there is a problem of increasing the water treatment load of the wastewater treatment facility in the factory or business site. In addition, a chemical cleaning method using an acid or an oxidizing agent may be used. In this case as well, in order to improve the removal rate, it is necessary to increase the amount of the chemical and the oxidizing agent, and after using the generated salt. There is a problem of increasing the processing load.
JP 2002-66255 A

  Even if a cleaning apparatus, which is a simple method for removing the basic substance from the basic substance-containing gas, is used alone, a high removal rate cannot be obtained efficiently. The present invention has been made paying attention to such circumstances, and an object of the present invention is to provide a basic gas treatment system that can stably and efficiently reduce the diffusion of a basic substance into the environment. To do.

  That is, the present invention relates to a cleaning apparatus for treating a basic substance in a basic substance-containing gas by bringing it into gas-liquid contact with water, an acidic substance or an oxide, and a basic substance leaked into a gas treated by the cleaning apparatus. A basic gas comprising: a backup processing device configured to continuously perform adsorption / desorption processing, and wherein the desorbed basic substance is returned to the inlet of the cleaning device. A processing system is provided.

  Further, in the present invention, the back-up treatment apparatus is configured such that a honeycomb-like adsorbent formed in a columnar shape or a cylindrical shape circulates the adsorption region and the regeneration region and continuously performs the adsorption / desorption treatment of the basic substance. The present invention provides a basic gas treatment system which is a continuous suction / desorption device constructed.

  In the present invention, it is preferable that the honeycomb adsorbent of the backup processing apparatus contains an ion exchange fiber.

  In the present invention, it is preferable that the ion exchange fiber is a cation exchange fiber in which at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, and a sulfonic acid group is bonded to the fiber matrix.

  In the present invention, the basic gas is preferably ammonia.

  According to the present invention, it becomes possible to provide a basic gas treatment system capable of stably and efficiently treating a basic substance from a basic substance-containing gas, and stably diffusing the basic gas into the environment. Can be reduced efficiently.

  FIG. 2 is a flow diagram of a basic gas processing system showing an example of a preferred embodiment of the present invention. The basic gas treatment system of the present invention can be broadly divided into a basic substance-containing gas, and a cleaning apparatus capable of treating a basic substance in gas-liquid contact with water, an acidic substance or an oxide, and Back-up that accepts the adsorption-treated gas discharged from the cleaning device, can adsorb and desorb the basic substance leaking in the treated gas, and can transport the desorption gas to the washing device And a processing device.

  In FIG. 2, the basic substance-containing gas discharged from a factory, work place, or the like is supplied from the lower part of the water washing tower by the blower 21, while the washing water is circulated from the water storage layer 23 by the water supply pump 24 by the circulation pump 25. And is sprayed from a spray nozzle 26 provided in the upper part of the washing tower. The basic substance-containing gas supplied from the lower part of the washing tower is washed with the spray water, and then the gas and mist are separated by the mist separator 22, the gas is discharged from the upper part of the washing tower, and the mist and water are It is discharged from the lower part of the washing tower and part of the water is recycled.

  In order to absorb the basic substance in the absorption liquid, the cleaning device is a liquid dispersion type cleaning tower such as a packed tower, a fluid absorption tower, a spray tower or a bubble tower by a method in which the basic substance-containing gas and the absorption liquid are brought into contact with each other. However, it is not particularly limited as long as it is an apparatus of a system in which water, an acidic substance or an oxidizing agent is brought into gas-liquid contact with gas for treatment.

  The treated gas discharged from the cleaning device passes through the treated gas introduction line 27, and the honeycomb adsorbent formed in a columnar shape as shown in FIG. 3 or a cylindrical shape as shown in FIG. The basic substance leaking in the treated gas was adsorbed and simultaneously processed by the backup processing apparatus 28. The gas is discharged as clean gas.

  Further, the backup processing device 28 has a function of returning the concentrated basic-containing desorption gas to the inlet of the cleaning device (a in FIG. 1). With this system, the concentration of basic gas from the apparatus can be reduced.

In consideration of the cost performance of the backup processing, the basic gas processing system preferably has a medium to large gas flow rate (several tens to several thousand m ³ / min), but is not particularly limited. .

  The honeycomb adsorbent used in the backup device preferably contains ion exchange fibers. This is because it is an ion-exchange fiber, and thus exhibits extremely high adsorption performance for basic substances such as ammonia.

  Here, the ion exchange fiber is preferably a cation exchange fiber in which at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, and a sulfonic acid group is bonded to the fiber matrix. Further, it is preferable that a functional group of 2.0 mmol or more, preferably 4.0 mmol or more is bonded to the fiber matrix.

  As the above-mentioned ion exchange fiber, polyvinyl alcohol-based, polystyrene-based, phenol-based, acrylonitrile-based fibers, woven fabrics, and non-woven fabrics that have been given ion exchange capability by radiation graft polymerization or chemical treatment can be used. As a cation exchange fiber having a carboxyl group, a acrylonitrile-based copolymer (a copolymer containing 60% or more of acrylonitrile) is spun, cross-linked with hydrazine, dried, nitric acid → caustic soda → hydrochloric acid-treated cross-linked acrylic The system fibers satisfy the durability against solvents and the high ion exchange properties at the same time and can be used. In addition, as the fiber having a sulfonic acid group, a fiber obtained by sulfonating a polyolefin resin / polystyrene resin composite spun with a sulfonating agent (sulfuric acid, fuming sulfuric acid, etc.) has high durability against solvents and high ion exchange. It is satisfying at the same time and can be used in the same way.

  The cleaning device has a gas cooling effect, and has the effects of lowering the temperature of the treated gas and improving the relative humidity. Since the removal rate of the backup processing apparatus can be remarkably improved by lowering the temperature of the treated gas, this combination is a very good combination in terms of improving the removal rate. In general, in the physical adsorption removal with an adsorbent, the removal rate decreases as the relative humidity increases. However, in the present invention, by using an adsorbent containing ion-exchange fibers, the acid-base reaction is basic. Because it is involved in gas adsorption and removal, there is a feature that does not cause significant performance degradation even if the relative humidity of the processing gas is high, and the characteristics of the cleaning device that reduces the temperature of the gas to be processed and improves the humidity can be used effectively. It becomes a backup device.

  In the basic gas treatment system shown in FIG. 2, the gas to be treated was cleaned under the following conditions.

〔Example〕
It was introduced into a water washing apparatus at a temperature of 28 ° C. containing an ammonia concentration of 600 ppm, a relative humidity of 60% and a gas to be treated of 100 Nm ³ / min, and water washing was performed with a liquid / gas ratio of 1 to ³ L / m ³ . The removal rate was 90%, and the ammonia concentration of the treated gas at the outlet of the cleaning device was 60 ppm.

  This treated gas was continuously introduced into the backup processing apparatus. The backup processing apparatus uses a disk-type basic gas concentrator having a diameter of 1450 mm and a thickness of 450 mm containing 70 wt% of ion exchange fibers, which will be described later. In the desorption process, the concentration ratio obtained by the adsorption air amount / desorption air amount is 10 times. The heated air at 110 ° C. was controlled as described above. The gas desorbed and concentrated in the backup processing apparatus was returned to the cleaning apparatus inlet. The ammonia concentration in the gas cleaned by the system of this example (the gas after the treatment in the backup processing apparatus) was reduced to 2 ppm or less, which is the detection limit. The ammonia concentration was measured using an ammonia gas detector tube No. 3M, no. Measured using 3H.

  The ion exchange fiber was produced by the following method. 10 parts by mass of an acrylonitrile copolymer consisting of 90% by mass of acrylonitrile and 10% by mass of vinyl acetate (intrinsic viscosity [n] = 1.2 in dimethylformamide at 30 ° C.) is 90 parts by mass of a 50% by mass aqueous rhodium soda solution. Spinning and drawing according to a conventional method using a spinning stock solution dissolved in the part (total draw ratio: 10 times), followed by drying and wet heat treatment in an atmosphere of dry bulb / wet bulb = 120 ° C./60° C. A fiber (single fiber fineness 0.9 dtex, fiber length 50 mm) was obtained. This raw fiber was subjected to a crosslinking introduction treatment (98 ° C., 6 hours) in a 20% by weight aqueous solution of hydrazine hydrate and washed with pure water. After washing and drying, acid treatment (90 ° C., 2 hours) in a 3% by weight nitric acid aqueous solution, followed by hydrolysis treatment in a 3% by weight aqueous caustic soda solution at 90 ° C. for 2 hours, further 1 After acid conversion with a weight% hydrochloric acid solution, it was washed with pure water. The obtained fiber had 6.1 mmol / g carboxyl group introduced into the fiber molecule. (Based on neutralization point measurement using 0.1 mol / L sodium hydroxide normal solution and phenolphthalein indicator)

  The present application is an invention relating to the treatment of basic gas, and “is an economically extremely high removal rate expressed by using a backup treatment apparatus using an adsorbent containing ion exchange fibers.” A system that installs a backup processing device that continuously processes adsorption and desorption after a cleaning device has been devised. It contributes to a wide range of fields related to exhaust gas treatment of acid gases and organic solvents, as well as basic gas treatment. Is possible.

Figure of one form of washing device An example in which a disk-type basic gas concentrator is used as a backup processing device. Example of cylindrical honeycomb device Example of cylindrical honeycomb device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Blower 2 Mist separator 3 Water storage tank 4 Water supply pump 5 Circulation pump 6 Spray nozzle 21 Blower 22 Mist separator 23 Water storage tank 24 Water supply pump 25 Circulation pump 26 Spray nozzle 27 Processing gas introduction line 28 Backup processing device 31 Concentrated gas 32 Desorption heating gas 33 Moisture content processing gas 34 Processing gas 35 Cylindrical honeycomb 36 Rotating direction 37 Desorption zone 38 Adsorption zone 39 Concentrated gas 40 Desorption heating gas 41 Moisture containing gas to be treated 42 Processing gas 43 Cylindrical honeycomb 44 Rotation Direction 45 Flow pipe 46 Metal box for mounting honeycomb

Claims (6)

A basic gas treatment system capable of removing a basic substance in a basic substance-containing gas comprising the following (1), (2) and (3): (1) water, an acidic substance or an oxide; Cleaning device for processing by gas-liquid contact (2) Device for continuously adsorbing / desorbing the basic substance leaked in the gas processed by the cleaning device (3) The desorbed basic material is washed Backup process configured to be returned to the device entrance The backup processing apparatus is configured such that a honeycomb-shaped adsorbent formed in a columnar shape or a cylindrical shape has an adsorption region and a regeneration region, and continuously performs adsorption / desorption processing of a basic substance. 2. The basic gas treatment system according to 1. The basic gas treatment system according to claim 1 or 2, wherein the adsorbent used for the honeycomb-like adsorbent of the backup treatment apparatus contains ion exchange fibers. The ion exchange fiber is a cation exchange fiber formed by binding at least one functional group selected from a group consisting of a hydroxyl group, a carboxyl group, and a sulfonic acid group to a fiber matrix. A basic gas treatment system according to 1. 4. The basic gas treatment system according to claim 1, wherein the ion exchange fiber is a crosslinked acrylic fiber. The basic gas treatment system according to any one of claims 1 to 5, wherein the basic gas is ammonia.

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