CN106512686A - Thermal desorption tail gas treatment system for organic contaminated soil - Google Patents

Abstract

The invention belongs to the field of organic polluted soil treatment and discloses a thermal analysis tail gas treatment system for organic polluted soil. The tail gas treatment system includes a cyclone dust collector, a first reactor, a second reactor, an air blower and a spray tower. The pollutants to be treated are firstly dedusted by the cyclone dust collector, and then enter the first reactor, and are adsorbed in the second reactor And heating catalytic decomposition, at the same time, the air separator provides oxygen for the heating catalytic decomposition process, and at the same time helps the cooling of the catalyst after the process is completed, and finally the pollutants to be treated enter the spray tower for further purification, so as to realize the tail gas treatment process. Through the present invention, the tail gas can be treated continuously without shutting down. At the same time, two sets of catalytic reactors are cleverly used to operate in parallel, and the operation of "adsorption-heating and catalytic decomposition" is performed in turn, which effectively treats organic pollutants while reducing energy consumption. Energy consumption and extra space are saved.

Description

A thermal analysis tail gas treatment system for organic polluted soil

technical field

The invention belongs to the field of organic polluted soil treatment, and more specifically relates to a thermal analysis tail gas treatment system for organic polluted soil.

Background technique

At present, there are many ways to treat contaminated soil, among which thermal desorption technology is one of the more commonly used and convenient ones. However, there are also problems such as high energy consumption, low utilization rate of heat energy, and the need for reprocessing of activated carbon used as exhaust gas adsorption.

Generally, the thermal desorption process is divided into two parts: thermal desorption and tail gas treatment. The thermal desorption part refers to the separation of pollutants from the soil at a relatively high temperature. The tail gas treatment part refers to the incineration or catalytic combustion of the desorbed pollutants at high temperature. or activated carbon adsorption, high-temperature incineration usually needs to be carried out at a high temperature of 1200 ° C, and the energy consumption accounts for more than 60% of the total energy consumption of the process. High, so it is difficult to apply on a large scale; and the existing catalytic combustion equipment is generally more complicated, it needs to first absorb and then desorb organic waste gas, so it needs to be equipped with desorption equipment, which not only leads to low efficiency of waste gas treatment, but also requires a lot of space and additional equipment investment. In addition, the catalyst used for catalytic combustion needs to be replaced regularly, and the replacement cost is high. At the same time, the efficiency of direct catalytic combustion equipment for treating low-concentration exhaust gas is low, and the heat generated during the combustion of pollutants cannot be effectively utilized, resulting in the failure of large-scale promotion and application of this technology.

Contents of the invention

Aiming at the above defects or improvement needs of the prior art, the present invention provides a thermal analysis exhaust gas treatment system for organic polluted soil, which uses two sets of catalytic reactors to operate in parallel and perform "adsorption concentration-catalytic decomposition" operation in turn, thereby solving the problem of The technical problems of high energy consumption and low treatment efficiency of the tail gas treatment system after thermal desorption.

In order to achieve the above object, according to one aspect of the present invention, a tail gas treatment system for thermal analysis of organic polluted soil is provided, the tail gas treatment system includes a cyclone dust collector, a first reactor, a second reactor, an air blower and a shower tower, characterized in that:

After the first reactor and the second reactor are connected in parallel, one end is connected to the cyclone dust collector, and the other end is connected to the spray tower. In addition, the first reactor and the second reactor have the same structure and communicate with each other , used to adsorb and heat catalytically decompose organic matter in the pollutants to be treated, a first valve and a second valve are respectively arranged between the cyclone dust collector and the first and second reactors, and the first valve and the The second valve opens any one of them, the first reactor and the second reactor are changed from parallel to series, and the pollutants to be treated enter the cyclone dust collector for dust removal, and then enter the first reactor or the second reactor The adsorption process is realized in the second reactor or the first reactor to realize heating and catalytic decomposition, and finally enter the spray tower for further purification, thereby realizing the tail gas treatment of the pollutants to be treated;

In addition, the air blower is in communication with both the first reactor and the second reactor, on the one hand to provide oxygen during the heating and catalytic decomposition, and on the other hand to provide oxygen to the second reaction after the heating and catalytic decomposition is completed. The catalyst in the reactor or the first reactor is cooled.

Preferably, the heating in the first reactor and the second reactor adopts one of electric heating or microwave heating.

Preferably, the arrangement of catalysts in the first reactor and the second reactor adopts one or a combination of quartz tube arrays, ceramic tube arrays or metal tube arrays.

Preferably, the catalyst in the first reactor and the second reactor is one or a combination of supported zeolite molecular sieves, supported alumina and porous oxides.

Preferably, a dehydration tower is also connected between the air blower and the first and second reactors to remove water vapor in the air and prevent hydrothermal aging of the catalyst in the first and second reactors .

Preferably, an alkaline aqueous solution is used in the spray tower to remove acid gas in the pollutants to be treated.

Generally speaking, compared with the prior art, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

1. The present invention uses the first valve and the second valve to change the first and second reactors into a series connection mode to continuously treat tail gas without shutting down. - Heating and catalytic decomposition" operation, which effectively treats organic pollutants while reducing energy consumption. In addition, compared with the prior art, the existing catalytic combustion first absorbs and then desorbs, which needs to be equipped with desorption equipment. The present invention does not require desorption Attached equipment saves energy consumption and additional space;

2. By adopting the air blower, the present invention can not only supplement oxygen, prevent the generation of toxic by-products, but also accelerate the cooling speed of the catalyst and improve the overall operating efficiency of the system;

3. In the present invention, through the selection of the catalyst and its arrangement, the catalyst can not only adsorb organic pollutants at low temperature, but also catalytically decompose pollutants at high temperature;

4. In the present invention, a dehydration tower is arranged between the air blower and the first and second reactors, which prevents catalysts in the first and second reactors while removing water vapor from the air. hydrothermal aging;

5. The present invention can effectively remove acid gases such as chlorine produced in the catalytic decomposition process by using a spray tower equipped with an alkaline aqueous solution to achieve the effect of purifying the gas.

Description of drawings

Fig. 1 is a schematic structural view of a tail gas treatment system constructed according to a preferred embodiment of the present invention;

Fig. 2 is the relationship between temperature and time in the first reactor and the second reactor constructed according to a preferred embodiment of the present invention.

Throughout the drawings, the same reference numerals are used to designate the same elements or structures, wherein:

1-cyclone dust collector 2-first valve 3-second valve 4-first ball valve 5-first reactor 6-second reactor 7-first exhaust port 8-second exhaust port 9-the first Two-way ball valve 10-dehydration tower 11-air fan 12-spray tower

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.

Fig. 1 is the structural representation of the tail gas treatment system built according to a preferred embodiment of the present invention; As shown in Fig. 1, a kind of tail gas treatment system of thermal analysis of organic polluted soil comprises cyclone dust collector 1, first valve 2, Second valve 3, first ball valve 4, first reactor 5, second reactor 6, first exhaust port 7, second exhaust port 8, second ball valve 9, dehydration tower 10, air fan 11 , Spray tower 12.

According to the embodiment of the present invention, the existing catalytic combustion system usually passes the waste gas generated by thermal analysis of polluted soil directly into the catalytic reactor after dust removal treatment, and usually carries out catalytic combustion reaction at not lower than 400°C to decompose the organic waste gas , so that not only the energy consumption is high, but also the treatment efficiency of pollutants is low, resulting in energy waste and cost increase. In the present invention, firstly, the waste gas generated by the thermal analysis of polluted soil is passed into the cyclone dust collector 1 for drying, dust reduction, and cooling treatment, which is beneficial to the low-temperature adsorption reaction of organic pollutants in the next step, and the first valve 2 and the second valve are switched alternately. 3. Form A and B respectively. When the state is A, open the first valve 2, close the first exhaust port 7, close the second valve 3, open the second exhaust port 8, and the first ball valve 4 and the second-way ball valve 9 communicate with the second reactor 6 respectively, and the state B is completely opposite to the valve state of A. In the state A, the first reactor 5 begins to absorb and concentrate organic pollutants at low temperature, and the discharged pure air is the same as that of A. The air blown out by the air blower 11 is mixed and then enters the second reactor 6. At this time, the temperature of the reactor 6 starts to be programmed to decompose the concentrated organic pollutants at high temperature, and is discharged to the spray tower 12 through 7, and the temperature is raised to a certain temperature. Keep it for a period of time, and then start to cool down. When the concentration of organic pollutants in 5 reaches a certain value, the temperature in 6 also drops to room temperature. At the same time, the concentrated organic pollutants on the catalyst in 6 have been completely decomposed, and the catalyst can Regeneration can be reused. At this time, switch to the B state, and the organic pollutants begin to re-adsorb and concentrate in 6, and the discharged pure air is mixed with the air blown out by the air fan 11 and enters the first reactor 5, while in 5 The concentrated organic pollutants are catalyzed and decomposed during the heating process, and are discharged to the spray tower 12 through the first exhaust port 7. The first reactor 5 and the second reactor 6 are electrically heated to the inside The loaded catalyst is heated, and the catalyst refers to a dual-function catalyst with adsorption and catalytic decomposition functions, such as loaded zeolite molecular sieve, loaded alumina, porous oxide, etc., and the air blower 11 specifically refers to externally purified The introduction of air into the catalytic reactor, on the one hand, provides additional oxygen during the catalytic decomposition process, avoiding the combustion of toxic by-products in an oxygen-deficient state; time. A soil thermal analysis tail gas treatment system provided by the present invention can treat tail gas continuously without shutting down. At the same time, two sets of catalytic reactors are cleverly used to operate in parallel, and the "adsorption-catalytic decomposition" operation is carried out in turn. Traditional catalytic equipment needs to be cleaned first. The exhaust gas is concentrated, then desorbed at high temperature to desorb the concentrated exhaust gas, and then decompose the desorbed exhaust gas at high temperature catalytically, the energy consumption of the whole process is very high.

According to an aspect of the embodiment of the present invention, the heating method of the first reactor 5 and the second reactor 6 can be one of electric heating or microwave heating, wherein microwave heating has the characteristics of fast heating speed and low energy consumption.

According to another aspect of the embodiment of the present invention, the arrangement of the catalysts in the first reactor 5 and the second reactor 6 may be one or a combination of quartz tube arrays, ceramic tube arrays or metal tube arrays.

According to one aspect of the present invention, the catalysts in the first reactor 5 and the second reactor 6 can be one or a combination of supported zeolite molecular sieves, supported alumina, and porous oxides.

Fig. 2 is according to the relation of temperature and time in the first reactor that a preferred embodiment of the present invention builds and the second reactor, as shown in Fig. 2, the temperature variation process of 2 reactors in the whole operation process, can be seen The temperature of the two reactors rises alternately. The low-temperature section is the adsorption and concentration stage of organic pollutants, and the high-temperature section is the catalytic decomposition stage of concentrated organic pollutants. Through longer-term low-temperature adsorption and shorter-term high-temperature catalysis, effective The energy consumption of the whole operation is reduced.

Those skilled in the art can easily understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (6)

1. A tail gas treatment system of thermal analysis of organic polluted soil, this tail gas treatment system comprises a cyclone dust collector (1), a first reactor (5), a second reactor (6), an air blower (11) and a shower Tower (12), characterized in that: After the first reactor (5) and the second reactor (6) are connected in parallel, one end is connected with the cyclone dust collector (1), and the other end is connected with the spray tower (12). In addition, the first The reactor (5) and the second reactor (6) have the same structure and communicate with each other, and are used to adsorb and heat and catalyze the decomposition of organic matter in the pollutants to be treated. The cyclone dust collector (1) and the first and second reactors A first valve (2) and a second valve (3) are respectively arranged between the reactors (5, 6), and any one of the first valve and the second valve is opened, and the first reactor and the second reaction The pollutants to be treated enter the cyclone dust collector for dust removal, then enter the first reactor or the second reactor to realize the adsorption process, and then pass through the second reactor or the first reactor realize heating and catalytic decomposition, and finally enter the spray tower for further purification, so as to realize the tail gas treatment of the pollutants to be treated; In addition, the air blower (11) is in communication with both the first reactor (5) and the second reactor (6), on the one hand to provide oxygen in the heating catalytic decomposition, on the other hand in the heating catalytic decomposition After the decomposition is completed, the temperature of the catalyst in the second reactor or the first reactor is lowered. 2. a kind of tail gas treatment system of thermal analysis of organic polluted soil according to claim 1, is characterized in that, the heating in described first reactor (5) and the second reactor (6) adopts electric heating or microwave One of the heating. 3. A tail gas treatment system for thermal analysis of organic polluted soil according to claim 1 or 2, characterized in that the catalyst arrangement in the first reactor (5) and the second reactor (6) One or a combination of quartz tube arrays, ceramic tube arrays or metal tube arrays is used. 4. according to any one of claim 1-3, the exhaust gas treatment system of a kind of thermal analysis of organic polluted soil is characterized in that, the catalyst in the first reactor (5) and the second reactor (6) One or a combination of supported zeolite molecular sieves, supported alumina and porous oxides is used. 5. according to the tail gas treatment system of a kind of thermal analysis of organic polluted soil described in any one of claim 1-4, it is characterized in that, described air blower (11) and described first, second reactor (5, 6) There is also a dehydration tower (10) connected therebetween for removing water vapor in the air and preventing hydrothermal aging of the catalysts in the first and second reactors. 6. A kind of organic polluted soil thermal analysis exhaust gas treatment system according to any one of claims 1-4, is characterized in that, adopts alkaline aqueous solution in the described spray tower (12), is used for removing the pollutant to be treated Intermediate acid gas.