METHOD FOR WASTE GAS DEDUSTING AND DEDUSTING AGENT

Abstract

A method and device for waste gas dedusting and a dedusting agent used in the method. A dust-containing waste gas (1) and an organic dedusting agent (4) are introduced into a dedusting tower (3), respectively, and make contact with each other in the tower; at least part of the water vapor in the dust-containing waste gas (1) is condensed, and the organic dedusting agent (4) and the condensed water adsorb solid particles, acidic pollutants, organic pollutants and/or heavy metal compounds in the dust-containing waste gas; and the resulting purified gas (2) is emptied out or subjected to a subsequent process. The organic dedusting agent (4) comprises a non-toxic and high boiling point organic solvent composition, being two or more selected from cooking oil, silicone oil, modified silicone oil, liquid-state asphalt oil, tung tree seed oil, liquid-state paraffin wax oil, mineral oil, palm oil and waste cooking oil.

Claims

1. A waste gas dedusting method comprising the following steps: a dust-containing waste gas and an organic dedusting agent are introduced into a dedusting tower, respectively, and come into contact in the tower; at least part of the water vapor in the dust-containing waste gas is condensed; solid particles, acidic contaminants, organic contaminants and/or heavy metal compounds in the dust-containing waste gas are adsorbed by the organic dedusting agent and the condensed water; and the resulting purified gas is vented or subjected to a subsequent process.

2. The waste gas dedusting method of claim 1, characterized in that the method further comprises the following steps: a mixed solution of the organic dedusting agent that has adsorbed solid particles, acidic contaminants, organic contaminants and/or heavy metal compounds and the condensed water enters a filter for solid-liquid separation, and ash dregs discharged from the filter are further treated or recycled for use; the resulting filtrate enters a storage tank for oil-water separation, an aqueous phase at the lower layer is discharged and further treated or recycled for use, and the organic dedusting agent at the upper layer is still returned to the dedusting tower for use.

3. The waste gas dedusting method of claim 1, characterized in that a countercurrent waste gas dedusting process is adopted, that is: the dust-containing waste gas enters a countercurrent dedusting tower from the lower part thereof, the organic dedusting agent enters the countercurrent dedusting tower from the upper part thereof and contacts with the dust-containing waste gas countercurrently in the tower; the resulting purified gas is vented from the top of the countercurrent dedusting tower or subjected to a subsequent process; and a mixed solution of the organic dedusting agent that has adsorbed solid particles, acidic contaminants, organic contaminants and/or heavy metal compounds and the condensed water is discharged from the bottom of the countercurrent dedusting tower.

4. The waste gas dedusting method of claim 1, characterized in that a cocurrent waste gas dedusting process is adopted, that is: both the dust-containing waste gas and the organic dedusting agent enter a cocurrent dedusting tower from the upper part thereof, and come into contact cocurrently in the tower; solid particles, acidic contaminants, organic contaminants and/or heavy metal compounds in the dust-containing waste gas are adsorbed by the organic dedusting agent and the condensed water, and the resulting gas and liquid in a mixture enter a gas-liquid separator together; the purified gas resulting from gas-liquid separation is vented from the top of the gas-liquid separator or subjected to a subsequent process, and a mixed solution of the organic dedusting agent that has adsorbed solid particles, acidic contaminants, organic contaminants and/or heavy metal compounds and the condensed water is discharged from the bottom of the gas-liquid separator.

5. The waste gas dedusting method of claim 1, characterized in that a hybrid-current waste gas dedusting process is adopted, that is: both the dust-containing waste gas and the organic dedusting agent enter a cocurrent dedusting tower from the upper part thereof, and come into contact cocurrently in the tower; the water vapor in the dust-containing waste gas is at least partially condensed, and at least part of the solid particles, acidic contaminants, organic contaminants and/or heavy metal compounds in the dust-containing waste gas are adsorbed by the organic dedusting agent and the condensed water; the gas-liquid mixture thus formed enters a countercurrent dedusting tower through the lower part of the cocurrent dedusting tower, and contacts in the tower countercurrently with the organic dedusting agent introduced from the upper part of the countercurrent dedusting tower; the resulting purified gas is vented from the top of the countercurrent dedusting tower or subjected to a subsequent process, and a mixed solution of the organic dedusting agent that has adsorbed solid particles, acidic contaminants, organic contaminants and/or heavy metal compounds and the condensed water is collected at the bottom of the countercurrent dedusting tower.

6. The waste gas dedusting method of claim 5, characterized in that part of the mixed solution of the organic dedusting agent and the condensed water at the bottom of the countercurrent dedusting tower is extracted by an internal circulation pump as an internal circulation dedusting agent, sprayed from the upper part of the cocurrent dedusting tower and contacts with the dust-containing waste gas cocurrently, and/or sprayed from the middle part of the countercurrent dedusting tower and contacts with the dust-containing waste gas countercurrently.

7. The waste gas dedusting method of claim 2, characterized in that the organic dedusting agent at the upper layer in said storage tank is extracted by a circulation pump and enters the dedusting tower for recycle use, or the organic dedusting agent at the upper layer in said storage tank is extracted by a circulation pump, cooled by a coolant in a heat exchanger, and then enters the dedusting tower for recycle use.

8. The waste gas dedusting method of claim 1, characterized in that the organic dedusting agent introduced into the dedusting tower has a temperature lower than 80° C.

9. The waste gas dedusting method of claim 1, characterized in that said organic dedusting agent comprises a non-toxic high boiling point organic solvent composition, being two or more selected from edible oil, silicone oil, modified silicone oil, liquid asphalt oil, tung seed oil, liquid paraffin oil, mineral oil, palm oil and waste cooking oil.

10. An apparatus for waste gas dedusting, comprising a dedusting tower, a filter and a storage tank, characterized in that the dedusting tower is provided with a dust-containing waste gas inlet and an organic dedusting agent inlet; the filter is connected to the bottom of the dedusting tower, and the storage tank is connected to the filter; the organic dedusting agent contacts with the dust-containing waste gas in the dedusting tower, the water vapor in the dust-containing waste gas is at least partially condensed, and adsorbs the solid particles, acidic contaminants, organic contaminants and/or heavy metal compounds in the dust-containing waste gas; a mixed solution of the organic dedusting agent after adsorption and the condensed water enters the filter for solid-liquid separation, the resulting ash dregs are discharged from the filter, and the resulting filtrate enters the storage tank, precipitates and becomes layered; the aqueous phase at the lower layer in the storage tank is discharged, and the organic dedusting agent at the upper layer is optionally returned to the dedusting tower for use.

11. The apparatus for waste gas dedusting of claim 10, characterized in that said dust-containing waste gas inlet is in the lower part of the dedusting tower, and the organic dedusting agent inlet is in the upper part of the dedusting tower; the organic dedusting agent contacts with the dust-containing waste gas countercurrently in the tower, and the resulting purified gas is vented from the top of the dedusting tower or subjected to a subsequent process.

12. The apparatus for waste gas dedusting of claim 10, characterized in that said apparatus for waste gas dedusting further comprises a gas-liquid separator, and the gas-liquid separator is connected to the bottom of the dedusting tower; both said dust-containing waste gas inlet and the organic dedusting agent inlet are in the upper part of the dedusting tower, the organic dedusting agent contacts with the dust-containing waste gas cocurrently in the tower, and the solid particles, acidic contaminants, organic contaminants and/or heavy metal compounds in the dust-containing waste gas are adsorbed by the organic dedusting agent and the condensed water; the resulting gas and liquid in a mixture enter the gas-liquid separator together for gas-liquid separation, and then the purified gas is vented from the top of the gas-liquid separator or subjected to a subsequent process; the mixed solution of the organic dedusting agent that has adsorbed solid particles, acidic contaminants, organic contaminants and/or heavy metal compounds and the condensed water is discharged from the bottom of the gas-liquid separator, and enters the filter for solid-liquid separation.

13. The apparatus for waste gas dedusting of claim 10, characterized in that said apparatus for waste gas dedusting comprises a cocurrent dedusting tower and a countercurrent dedusting tower, both the dust-containing waste gas and the organic dedusting agent enter the cocurrent dedusting tower from an upper inlet thereof, and come into contact cocurrently in the tower; the water vapor in the dust-containing waste gas is at least partially condensed, and at least part of the solid particles, acidic contaminants, organic contaminants and/or heavy metal compounds in the dust-containing waste gas are adsorbed by the organic dedusting agent and the condensed water; the gas-liquid mixture thus formed enters the countercurrent dedusting tower through the lower part of the cocurrent dedusting tower, and contacts in the tower countercurrently with the organic dedusting agent introduced from the upper part of the countercurrent dedusting tower; the resulting purified gas is vented from the top of the countercurrent dedusting tower or subjected to a subsequent process, and the mixed solution of the organic dedusting agent that has adsorbed solid particles, acidic contaminants, organic contaminants and/or heavy metal compounds and the condensed water is collected at the bottom of the countercurrent dedusting tower.

14. The apparatus for waste gas dedusting of claim 13, characterized in that said apparatus for waste gas dedusting further comprises an internal circulation pump, and part of the mixed solution of the organic dedusting agent and the condensed water is extracted from the bottom of the countercurrent dedusting tower, sprayed from the upper part of the cocurrent dedusting tower and contacts with the dust-containing waste gas cocurrently, and/or sprayed from the middle part of the countercurrent dedusting tower and contacts with the dust-containing waste gas countercurrently.

15. The apparatus for waste gas dedusting of claim 10, characterized in that said apparatus for waste gas dedusting further comprises a circulation pump, and the organic dedusting agent at the upper layer in the storage tank is extracted by the circulation pump, and introduced into the dedusting tower for recycle use.

16. The apparatus for waste gas dedusting of claim 10, characterized in that said apparatus for waste gas dedusting further comprises a circulation pump and a heat exchanger, the organic dedusting agent at the upper layer in the storage tank is extracted by the circulation pump, cooled by a coolant in the heat exchanger, and then enters the dedusting tower for recycle use.

17. The apparatus for waste gas dedusting of claim 16, characterized in that said apparatus for waste gas dedusting further comprises a heat pump system, such that the coolant that is warmed by heat absorption is subjected to afterheat recovery.

18. The apparatus for waste gas dedusting of claim 10, characterized in that a packing layer or an atomizing nozzle is provided in said dedusting tower.

19. An organic dedusting agent comprising a non-toxic high boiling point organic solvent composition, being two or more selected from edible oil, silicone oil, modified silicone oil, liquid asphalt oil, tung seed oil, liquid paraffin oil, mineral oil, palm oil and waste cooking oil.

20. The organic dedusting agent of claim 19, characterized in that said edible oil is selected from one or more of peanut oil, salad oil, olive oil, castor oil, camellia seed oil, rape seed oil, corn oil, various plant germ oils and soybean oil.

21. The organic dedusting agent of claim 19, characterized in that said organic dedusting agent comprises a silicon-based modifier, said silicon-based modifier is preferably a silicone oil or a modified silicone oil.

22. The organic dedusting agent of claim 21, characterized in that said modified silicone oil is a silicone oil modified by hydroxylation and/or amination and/or carboxylation and/or acylation.

Description

DESCRIPTION OF DRAWINGS

[0047] FIG. 1 is a schematic diagram illustrating technical process and apparatus for countercurrent waste gas dedusting, in which: 1 represents a waste gas before dedusting, 2 represents a waste gas after purification, 3 represents a countercurrent dedusting tower, 4 represents an organic dedusting agent, 5 represents ash dregs, 6 represents a filter, 7 represents a storage tank, 8 represents a circulation pump, 9 represents a heat exchanger, 10 represents a coolant, and 11 represents a coolant that is warmed.

[0048] FIG. 2 is a schematic diagram illustrating technical process and apparatus for cocurrent waste gas dedusting, in which: 1 represents a waste gas before dedusting, 2 represents a waste gas after purification, 4 represents an organic dedusting agent, 5 represents ash dregs, 6 represents a filter, 7 represents a storage tank, 8 represents a circulation pump, 9 represents a heat exchanger, 10 represents a coolant, 11 represents a coolant that is warmed, 12 represents a cocurrent dedusting tower, and 13 represents a gas-liquid separator.

[0049] FIG. 3 is a schematic diagram illustrating technical process and apparatus for hybrid-current waste gas dedusting, in which: 1 represents a waste gas before dedusting, 2 represents a waste gas after purification, 3 represents a countercurrent dedusting tower, 4 represents an organic dedusting agent, 5 represents ash dregs, 6 represents a filter, 7 represents a storage tank, 8 represents a circulation pump, 9 represents a heat exchanger, 10 represents a coolant, 11 represents a coolant that is warmed, 12 represents a cocurrent dedusting tower, 14 represents an internal circulation pump, and 15 represents an internal circulation dedusting agent.

[0050] FIG. 4 is another schematic diagram illustrating technical process and apparatus for hybrid-current waste gas dedusting, in which: 1 represents a waste gas before dedusting, 2 represents a waste gas after purification, 3 represents a countercurrent dedusting tower, 4 represents an organic dedusting agent, 5 represents ash dregs, 6 represents a filter, 7 represents a storage tank, 8 represents a circulation pump, 9 represents a heat exchanger, 10 represents a coolant, 11 represents a coolant that is warmed, 12 represents a cocurrent dedusting tower, 14 represents an internal circulation pump, 15 represents an internal circulation dedusting agent (part of the internal circulation dedusting agent is sprayed partially from the top of the cocurrent dedusting tower 12 used for pressurizing and dedusting and contacts with the dust-containing waste gas cocurrently, and another part of the internal circulation dedusting agent is sprayed from the middle part of the countercurrent dedusting tower 3 and contacts with the dust-containing waste gas countercurrently), and 16 represents a packing layer.

DETAILED DESCRIPTION OF EMBODIMENTS

[0051] The waste gas dedusting technical process and apparatus according to the present invention will be described below in conjunction with specific embodiments. Said embodiments are intended to better illustrate the present invention, and should not be construed as limitations to the claims of the present invention.

[0052] The operation methods are as follows:

[0053] A countercurrent waste gas dedusting technical process and an apparatus are shown in FIG. 1: in operation, a waste gas before dedusting 1 is introduced into a countercurrent dedusting tower 3 from bottom, an organic dedusting agent 4 is introduced into the countercurrent dedusting tower 3 from top, and the waste gas before dedusting 1 and the organic dedusting agent 4 come into contact countercurrently in the countercurrent dedusting tower 3; dusts, HCl, HF, dioxins, polycyclic aromatic hydrocarbons, other organic substances, heavy metal compounds and the like in the waste gas before dedusting 1 are adsorbed by the organic dedusting agent 4 and condensed water, thus the waste gas before dedusting 1 is converted into a waste gas after purification 2 and vented from the top of the countercurrent dedusting tower 3; a mixed solution of the organic dedusting agent 4 that has adsorbed dusts, HCl, HF, dioxins, polycyclic aromatic hydrocarbons, other organic substances, heavy metal compounds and the like and the condensed water is collected at the bottom of the countercurrent dedusting tower 3, then flows out from the bottom of the countercurrent dedusting tower 3 and enters a filter 6 for filtration; the separated ash dregs 5 are discharged from the filter 6, and the filtrate enters a storage tank 7, precipitates and becomes layered; the bottom is an aqueous layer containing HCl, HF, dioxins, polycyclic aromatic hydrocarbons, other organic substances, heavy metal compounds and the like, which is discharged, and further treated or recycled for use; the organic dedusting agent at the upper layer is delivered by a circulation pump 8, and cooled down by a coolant 10 in a heat exchanger 9, thus is converted into a clean organic dedusting agent 4 and enters the countercurrent dedusting tower 3 for reuse; after absorbing heat from the organic dedusting agent 4, the coolant 10 is converted into a coolant that is warmed 11, which can be utilized for afterheat recovery; in the case that the waste gas before dedusting 1 does not need to be cooled down, the clean organic dedusting agent 4 delivered by the circulation pump 8 can be introduced directly into the countercurrent dedusting tower 3, in which case the heat exchanger 9, the coolant 10 and the coolant that is warmed 11 in the industrial process may be omitted.

[0054] A cocurrent waste gas dedusting technical process and an apparatus are shown in FIG. 2: in operation, a waste gas before dedusting 1 is introduced into a cocurrent dedusting tower 12 from top, an organic dedusting agent 4 is also introduced into the cocurrent dedusting tower 12 from top, and the waste gas before dedusting 1 and the organic dedusting agent 4 come into contact cocurrently in the cocurrent dedusting tower 12; dusts, HCl, HF, dioxins, polycyclic aromatic hydrocarbons, other organic substances, heavy metal compounds and the like in the waste gas before dedusting 1 are adsorbed by the organic dedusting agent 4 and condensed water, thus the waste gas before dedusting 1 is converted into a waste gas after purification 2, and enters a gas-liquid separator 13 from the bottom of the cocurrent dedusting tower 12 for gas-liquid separation, and then vented from the top of the gas-liquid separator 13; a mixed solution of the organic dedusting agent 4 that has adsorbed dusts, HCl, HF, dioxins, polycyclic aromatic hydrocarbons, other organic substances, heavy metal compounds and the like and the condensed water is collected at the bottom of the cocurrent dedusting tower 12, enters the gas-liquid separator 13 for gas-liquid separation, then flows out from the bottom of the gas-liquid separator 13 and enters a filter 6 for filtration; the separated ash dregs 5 are discharged from the filter 6, and the filtrate enters a storage tank 7, precipitates and becomes layered; the bottom is an aqueous layer containing HCl, HF, dioxins, polycyclic aromatic hydrocarbons, other organic substances, heavy metal compounds and the like, which is discharged, and further treated or recycled for use; the organic dedusting agent 4 at the upper layer is delivered by a dedusting pump 8, and cooled down by a coolant 10 in a heat exchanger 9, thus is converted into a clean organic dedusting agent 4 and enters the cocurrent dedusting tower 12 for reuse; after absorbing heat from the organic dedusting agent, the coolant 10 is converted into a coolant that is warmed 11, which can be utilized for afterheat recovery; in the case that the waste gas before dedusting 1 does not need to be cooled down, the clean organic dedusting agent 4 delivered by the circulation pump 8 can be introduced directly into the cocurrent dedusting tower 12, in which case the heat exchanger 9, the coolant 10 and the coolant that is warmed 11 in the industrial process may be omitted.

[0055] A hybrid-current waste gas dedusting technical process and an apparatus are shown in FIG. 3: in operation, a waste gas before dedusting 1 is introduced into a cocurrent dedusting tower 12 from top, and an internal circulation dedusting agent 15 extracted by an internal circulation pump 14 from the bottom of a countercurrent dedusting tower 3 is also introduced into the cocurrent dedusting tower 12 from top; the waste gas before dedusting 1 and the internal circulation dedusting agent 15 come into contact cocurrently in the cocurrent dedusting tower 12, most of the dusts, HCl, HF, dioxins, polycyclic aromatic hydrocarbons, other organic substances, heavy metal compounds and the like in the waste gas before dedusting 1 are adsorbed by the internal circulation dedusting agent 15 and condensed water, thus a gas-liquid mixture is formed, and enters the countercurrent dedusting tower 3 from the bottom of the cocurrent dedusting tower 12; at the bottom of the countercurrent dedusting tower 3, the internal circulation dedusting agent 15 is separated from the partially purified waste gas before dedusting 1; the waste gas is introduced into the countercurrent dedusting tower 3 from bottom, the organic dedusting agent 4 is introduced into the countercurrent dedusting tower 3 from top, and the partially purified waste gas and the organic dedusting agent 4 come into contact countercurrently in the countercurrent dedusting tower 3; the remaining dusts, HCl, HF, dioxins, polycyclic aromatic hydrocarbons, other organic substances, heavy metal compounds and the like in the waste gas are adsorbed by the organic dedusting agent 4 and condensed water, the waste gas is converted into a waste gas after purification 2 and vented from the top of the countercurrent dedusting tower 3; a mixed solution of the organic dedusting agent 4 that has adsorbed dusts, HCl, HF, dioxins, polycyclic aromatic hydrocarbons, other organic substances, heavy metal compounds and the like and the condensed water is collected at the bottom of the countercurrent dedusting tower 3, part of the mixed solution is extracted by the internal circulation pump 14 as the internal circulation dedusting agent 15 and enters the cocurrent dedusting tower 12 from top for recycle use, the remainder flows out from the bottom of the countercurrent dedusting tower 3, and enters the filter 6 for filtration; the separated ash dregs 5 are discharged from the filter 6, and the filtrate enters a storage tank 7, precipitates and becomes layered; the bottom is an aqueous layer containing HCl, HF, dioxins, polycyclic aromatic hydrocarbons, other organic substances, heavy metal compounds and the like, which is discharged, and further treated or recycled for use; the organic dedusting agent at the upper layer is delivered by a dedusting pump 8, and cooled down by a coolant 10 in a heat exchanger 9, thus is converted into a clean organic dedusting agent 4 and enters the countercurrent dedusting tower 3 for reuse; after absorbing heat from the dedusting agent, the coolant 10 is converted into a coolant that is warmed 11, which can be utilized for afterheat recovery; in this technical process, the internal circulation dedusting agent 15 may also be replaced by the clean organic dedusting agent 4, in which case the internal circulation pump 14 may be omitted; consequently, the clean organic dedusting agent 4 coming out from the heat exchanger 9 should be divided into two streams, one enters the countercurrent dedusting tower 3, and the other enters the cocurrent dedusting tower 12 directly from top; in the case that the waste gas before dedusting 1 does not need to be cooled down, the clean organic dedusting agent 4 delivered by the circulation pump 8 can be introduced directly into the countercurrent dedusting tower 3, in which case the heat exchanger 9, the coolant 10 and the coolant that is warmed 11 in the industrial process may be omitted.

[0056] As shown in FIG. 4: in the technical process of hybrid-current waste gas dedusting, the internal circulation dedusting agent 15 may also be divided into two streams, one is sprayed from the top of the cocurrent dedusting tower 12 used for pressurizing and dedusting and directly contacts with the dust-containing waste gas 1 cocurrently, and the other is sprayed from the middle part of the countercurrent dedusting tower 3 and contacts with the preliminarily purified dust-containing waste gas countercurrently; a packing layer 16 may also be provided in the countercurrent dedusting tower 3 to improve the condensation efficiency.

[0057] In Example 1, a laboratory absorption bottle was used, and 200 ml of modified silicone oil was charged into the absorption bottle. Dedusting test was carried out as follows: in Huzhou, Zhejiang province, a company utilized petroleum cokes as raw materials to produce glass with a production of 800 tons per day; its kiln exhaust gas was passed through a bag-type dedustor, and an exhaust gas was extracted directly from a pipeline thereof; A 1 Nm.sup.3 exhaust gas was extracted, passed through the absorption bottle, and was absorbed by the 200 ml modified silicone oil in the absorption bottle; the 200 ml modified silicone oil with absorbed dusts was subjected to centrifugal separation, whereupon four layers were formed in the centrifuge tube after the centrifugal separation: the bottom layer was a layer of dregs, followed by an aqueous layer, then was a layer of solid organic substances, and the uppermost layer was a layer of modified silicone oil; By drying and weighing, the layer of ash dregs weighed 2.3546 g, and the layer of solid organic substances weighed 0.3213 g; thus the content of dusts and organic substances in the glass kiln combustion exhaust gas after bag-type dedusting was 2.3546 g+0.3213 g=2.6759 g/Nm.sup.3, whereas in actual production, the dust content detected by an instrument was only around 0.8 g/Nm.sup.3, indicating that the method of the present invention has a dedusting efficiency much higher than that of the methods used in actual production.

[0058] In Example 2, a laboratory absorption bottle was used, and a 200 ml mixture of peanut oil and modified silicone oil was charged into the absorption bottle. Dedusting test was carried out as follows: in Hainan province, a company utilized natural gases as raw materials to produce glass with a production of 600 tons per day; its kiln exhaust gas was subjected to denitration and alkaline desulfurization, and an exhaust gas was extracted directly from a pipeline thereof; A 0.6 Nm.sup.3 exhaust gas was extracted, passed through the absorption bottle, and was absorbed by the 200 ml mixture of peanut oil and modified silicone oil in the absorption bottle; the 200 ml mixture of peanut oil and modified silicone oil with absorbed dusts was subjected to centrifugal separation, whereupon three layers were formed in the centrifuge tube after the centrifugal separation: the bottom layer was a layer of dregs, followed by an aqueous layer, and the uppermost layer was a mixed liquid layer of peanut oil and modified silicone oil; By drying and weighing, the layer of ash dregs weighed 0.5347 g; thus the content of dusts in the glass kiln combustion exhaust gas after denitration and alkaline desulfurization was 0.5347 g/0.6=0.8911 g/Nm.sup.3, whereas in actual production, the enterprise detected a dust content of less than 0.1 g/Nm.sup.3, indicating that the method of the present invention has a dedusting efficiency much higher than that of the methods used in actual production.