CN113144878A

CN113144878A - Dry-wet combined desulfurization and dust removal method for waste gas generated in brick making by blending burned sludge

Info

Publication number: CN113144878A
Application number: CN202110377280.8A
Authority: CN
Inventors: 李宇翔; 胡满深; 周景堂; 潘柏盛; 温超强
Original assignee: Jiangmen Tongli Environmental Protection Technology Co ltd
Current assignee: Jiangmen Tongli Environmental Protection Technology Co ltd
Priority date: 2021-04-08
Filing date: 2021-04-08
Publication date: 2021-07-23

Abstract

The invention provides a dry-wet combined desulfurization and dust removal method for waste gas generated in brick making by blending burned sludge, and relates to the technical field of environmental protection. The invention adopts a dry-wet combined desulfurization and dust removal system to carry out desulfurization and dust removal, and comprises the following steps: treating waste gas of a drying kiln: introducing waste gas generated in the step of drying the blended-burned sludge in the step of brickmaking into a dry-method desulfurization and dust removal system, performing semi-dry-method desulfurization, and removing dust after desulfurization; treating sintering kiln waste gas: introducing waste gas generated in the step of sintering the blended sludge for brickmaking into a wet desulphurization and dust removal system for wet desulphurization, and removing dust after desulphurization; merging and discharging flue gas: and introducing the waste gas treated by the dry-method desulfurization and dust removal system and the waste gas treated by the wet-method desulfurization and dust removal system into a waste gas collecting system for mixing, and discharging the mixture after the detection is qualified. The invention carries out shunting treatment according to the property of the waste gas, reduces equipment faults, is beneficial to reducing the operation cost, and the treated waste gas meets the emission standard.

Description

Dry-wet combined desulfurization and dust removal method for waste gas generated in brick making by blending burned sludge

Technical Field

The invention relates to the technical field of environmental protection, in particular to a dry-wet combined desulfurization and dust removal method for waste gas generated in brick making by blending burned sludge.

Background

In order to reduce sewage discharge and improve the utilization rate of raw materials, the cement and tile industry can utilize self tunnel kilns or industrial kilns such as annular kilns and the like to mix strict waste such as printing and dyeing sludge, municipal sludge and the like into the raw materials according to a certain proportion to prepare the bricks. The production flow of the brick making by mixing and burning the sludge mainly comprises three steps: drying, namely drying the sludge from the water content of 60% to 40% by using a biomass rotary kiln; making bricks, mixing the materials according to a proper material ratio, and pressing the mixed raw materials into green bricks by using a brick making machine; and (4) sintering, namely conveying the pressed green bricks into a tunnel kiln for sintering treatment to finish the firing of the environment-friendly bricks.

Waste gas generated in the existing brick making by blending and burning sludge is usually treated by a wet desulphurization and dust removal method, and a large amount of organic waste gas generated in the drying process is directly discharged into kiln flue gas treatment equipment, so that COD (chemical oxygen demand) and ammonia nitrogen in circulating slurry of a wet desulphurization and dust removal system are high, secondary pollution is generated, and the subsequent treatment cost is high; the circulation tank can accumulate organic matter sediment after a period of time, the tank cleaning treatment is needed, the system availability ratio and the continuous operation working condition are seriously influenced, and the factory is forced to stop production and clean in serious cases. Therefore, the existing treatment mode of the waste gas generated in the brick making by blending and burning the sludge needs to be improved so as to reduce the influence caused by the problems and reduce the treatment cost.

Disclosure of Invention

Based on the above, it is necessary to provide a dry-wet combined desulfurization and dust removal method for waste gas generated in the brick making process by blending burned sludge, so as to split-flow the waste gas generated in the drying step and the sintering step in the brick making process, effectively prevent a large amount of organic pollutants generated in the drying step from entering wet desulfurization and dust removal equipment, and be beneficial to reducing the operation cost, and the treated waste gas meets the emission standard.

A dry-wet combined desulfurization and dust removal method for waste gas generated in brick making by blending burned sludge is characterized in that a dry-wet combined desulfurization and dust removal system is adopted for desulfurization and dust removal, and the dry-wet combined desulfurization and dust removal system comprises:

the dry desulfurization and dust removal system comprises a lime bin, a dry desulfurization tower, a dust remover and an absorber which are sequentially connected; the lower end of the dry desulfurization tower is provided with a first waste gas inlet and a material inlet, and the upper end of the dry desulfurization tower is provided with a first waste gas outlet; the lime bin is communicated with a material inlet of the dry desulfurization tower; the dry desulfurization and dust removal system also comprises a humidifying device used for providing a humidifying material, and the humidifying device is communicated with the dry desulfurization tower;

the wet desulphurization and dust removal system comprises a pulping tank, a circulating tank and a wet desulphurization tower which are connected in sequence; the lower end of the wet desulphurization tower is provided with a second waste gas inlet, the upper end of the wet desulphurization tower is provided with a second waste gas outlet, and the wet desulphurization tower is sequentially provided with a spraying device and a dedusting and demisting device from the second waste gas inlet to the second waste gas outlet; the circulating tank is connected with the spraying device;

the waste gas collecting system is provided with a first inlet and a second inlet, the adsorber is communicated with the first inlet, the second waste gas outlet is communicated with the second inlet, and the upper end of the waste gas collecting system is also provided with a discharge port for discharging waste gas;

the dry-wet combined desulfurization and dust removal method for the waste gas generated by making bricks by using the co-combustion sludge comprises the following steps:

treating waste gas of a drying kiln: introducing waste gas generated in the step of drying the blended-burned sludge in the step of brickmaking into a dry-method desulfurization and dust removal system, performing semi-dry-method desulfurization, and removing dust after desulfurization;

treating sintering kiln waste gas: introducing waste gas generated in the step of sintering the blended sludge for brickmaking into a wet desulphurization and dust removal system for wet desulphurization, and removing dust after desulphurization;

merging and discharging flue gas: and introducing the waste gas treated by the dry-method desulfurization and dust removal system and the waste gas treated by the wet-method desulfurization and dust removal system into a waste gas collecting system for mixing, and discharging the mixture after the detection is qualified.

In the practical process of the applicant, the difference of the pollutants in the waste gas generated in the drying step and the sintering step in the brick making process by mixing and burning the sludge is large: in the drying step, the pollutants in the waste gas mainly come from the decomposition and volatilization of organic components in the flue gas generated by biomass combustion and the sludge in the drying process, and the main components are dust and acid gas (HF, HCl and SO)₂、SO₃、NO_XEtc.), CO, heavy metals (Cd, Ti, Sb, As, Pb, Cr, CO, Cu, Mn, Ni, etc.), dioxins, a large number of volatile organic compounds (methane, ethane, propane, propionic acid, etc.), part of inorganic pollutants (NH₃、H₂S, HCN, etc.) and a large amount of water vapor; in the sintering process, pollutants in the flue gas mainly come from the flue gas generated by burning fuel coal and sintering green bricks, and because a large amount of volatile organic compounds are volatilized in the drying process, the main components of the flue gas are dust and acid gas (HF and SO)₂、NO_XEtc.) and a large amount of water vapor. The prior art generally treats the waste gas generated in the whole brick making process intensively, thereby causing the problems mentioned in the background art. The applicant gets rid of the thought inertia of the prior art, the brick making process of the co-fired sludge is separated, the waste gases generated in the drying step and the brick making step are respectively treated, the semi-dry desulfurization method and the wet desulfurization method are respectively adopted for desulfurization treatment according to the pollutant and property difference of the two waste gases, and finally the two waste gases are collected, the high-temperature flue gas (the temperature is about 80-100 ℃) after the semi-dry desulfurization method is mixed with the low-temperature flue gas (the temperature is about 55 ℃) after the wet desulfurization, the low-temperature flue gas is heated and whitened (the temperature reaches about 70 ℃), and the phenomenon of wet smoke plume is favorably reduced.

Based on the conception, the applicant provides the dry-wet combined desulfurization and dust removal method. The method comprises the steps of shunting and treating two waste gases generated in the drying step and the sintering step in the brick making process, wherein one waste gas is high-humidity organic waste gas generated in the drying step and dehydrated by waste heat, the waste gas is subjected to semidry desulfurization and dust removal by using a dry desulfurization and dust removal system, the other waste gas is high-air-quantity low-concentration low-temperature sulfur-containing dust-containing flue gas generated in the sintering step, the waste gas is subjected to wet desulfurization and dust removal by using a wet desulfurization and dust removal system, the shunting treatment can effectively avoid the problems of poor continuity and equipment damage caused by the fact that a large amount of organic pollutants generated in the drying step enter wet desulfurization and dust removal equipment, the operation cost is favorably reduced, and the treated waste gas meets the emission standard.

In one embodiment, the flue gas collecting system is fixed above the wet desulfurization tower. Preferably, the exhaust gas collecting system and the wet desulphurization tower are of an integrated structure. The desulfurized waste gas in the wet desulfurization tower directly rises into a waste gas collecting system and is mixed and collected with the waste gas desulfurized by the dry method or the semi-dry method.

In one embodiment, the humidifying device comprises an atomizer, a water conveying pipeline and a compressed air pipeline, wherein one end of the water conveying pipeline is communicated with the atomizer, the compressed air pipeline is communicated with the atomizer, and the atomizer is communicated with the material inlet. The water conveying pipeline is used for conveying water for the atomizer, the compressed air pipeline is used for conveying compressed air for the atomizer, and the water is sprayed out of the atomizer under the action of the compressed air to form atomized water drops. The humidifying device can not only humidify the dry absorbent (such as lime) but also cool the exhaust gas.

In one embodiment, the dust remover is a three-unit dust remover.

In one embodiment, the dust removal system comprises a one-unit dust remover, a two-unit dust remover and a three-unit dust remover which are connected in parallel.

In one embodiment, the adsorber is an activated carbon adsorption tank.

In one embodiment, the lower end of the dry desulfurization tower is provided with a vertical venturi tube, the lower end of the venturi tube is communicated with the first waste gas inlet, and the upper end of the venturi tube is communicated with the material inlet.

Waste gas enters from the lower end of the Venturi tube, the waste gas is accelerated to form a strong internal turbulent flow airflow through the acceleration effect of the Venturi tube, desulfurization materials (adsorbents such as lime and the like) and spray are converged into the turbulent flow airflow at the upper end of the Venturi tube, the contact time of the waste gas, the spray and the adsorbents is prolonged in the continuous upward and backflow process of the turbulent flow airflow, and the utilization rate and the desulfurization efficiency of the adsorbents are improved.

In one embodiment, the spraying device comprises at least three radial spraying layers and one reverse spraying layer.

In one embodiment, the spraying device comprises a first radial spraying layer, a second radial spraying layer, a third radial spraying layer and a reverse spraying layer which are sequentially arranged from bottom to top.

In one embodiment, the dust and mist removing device comprises at least one layer of wire mesh mist eliminator, at least two layers of folded plate mist eliminators and/or cyclone tube bundle mist eliminators.

In one embodiment, the dust and mist removal device comprises a wire mesh mist eliminator, a folded plate mist eliminator and a cyclone tube bundle mist eliminator which are sequentially arranged from bottom to top.

In one embodiment, the rotational flow tube bundle demister comprises an upper orifice plate and a lower orifice plate, a vertically arranged tube bundle is arranged between the upper orifice plate and the lower orifice plate, and turbulence balls are arranged in the tube bundle.

In one embodiment, the turbulence balls are solid turbulence balls and/or hollow turbulence balls.

In one embodiment, a back washing device for washing the wire mesh demister, the folded plate demister or the cyclone tube bundle demister is further arranged in the wet desulphurization tower, and the back washing device is connected with a back washing tank.

In one embodiment, the circulation tank is communicated with the bottom of the wet desulphurization tower.

In one embodiment, the wet desulphurization and dust removal system further comprises a plurality of sedimentation tanks, and the sedimentation tanks are communicated with the bottom of the circulation tank.

In one embodiment, the step of treating the exhaust gas of the drying kiln comprisesThe mass ratio of calcium in the desulfurization material in the dry-method desulfurization tower to sulfur in the waste gas is less than or equal to 2.0 within the unit time, the flow speed of the waste gas entering the desulfurization tower is 4.0-5.0 m/s, and the flow speed of the humidifying material is 1.0-1.4 m³The compressed air flow rate is 1.5-1.7 m³Min; the inner diameter of the absorption section of the dry desulfurization tower is 1.7-1.9 m, and the height of the absorption section of the dry desulfurization tower is 13.5-14.5 m. If the calcium-sulfur ratio is too high, the operation cost is increased; if the calcium-sulfur ratio is too low, the desulfurization rate may be lowered. If the amount of the humidifying material (namely the water spraying amount) is too much, the dry powder desulfurizer is easy to agglomerate, the fluidization effect is influenced, and the desulfurization efficiency is reduced; if the amount of the humidifying material (namely the water spraying amount) is too small, the cooling effect is not obvious, and the total amount of the working condition flue gas can be reduced by reducing the temperature of the flue gas, so that the flow rate of the flue gas is reduced, the retention time is increased, and the desulfurization rate is improved. The exhaust gas speed is too fast, the retention time is insufficient, and the desulfurization rate is reduced; too slow a velocity of the exhaust gas will not result in an effective fluidization.

In one embodiment, in the step of treating the waste gas of the drying kiln, the parameter indexes of the venturi tube are as follows: the inner diameter of the inlet is 1.0-1.2 m, the inner diameter of the throat is 0.77-0.79 m, the inner diameter of the outlet is 1.7-1.9 m, the height is 2.1-2.2 m, and the flow velocity of the throat is 57.0-57.5 m/s.

In one embodiment, the treated waste gas of the dry desulfurization dust removal system accounts for more than 40% of the total treated waste gas in unit time.

Compared with the prior art, the invention has the following beneficial effects:

the method of the invention carries out the shunting treatment on two waste gases generated in the drying step and the sintering step in the brick making process, one is the high-humidity organic waste gas dehydrated by the waste heat generated in the drying step, the waste gas is desulfurized and dedusted by a semi-dry method by using a dry method desulfurization and dedusting system, the other is the high-air-quantity low-concentration low-temperature sulfur-containing dust-containing flue gas generated in the sintering step, the waste gas is desulfurized and dedusted by a wet method by using a wet method desulfurization and dedusting system, the shunting treatment can effectively avoid the problems of poor continuity and equipment damage caused by the fact that a large amount of organic pollutants generated in the drying step enter wet method desulfurization and dedusting equipment, the operation cost is favorably reduced, and the treated waste gas meets the emission standard. The waste gas treated by the method of the inventionThe following effects can be achieved: the reduced concentration of the particles is less than or equal to 10mg/Nm³，SO₂The reduced concentration is less than or equal to 35mg/Nm³，NO_XThe discharge concentration is less than or equal to 200mg/Nm³(emission concentration converted to 18% baseline oxygen content). The treated indexes meet the national treatment standard of the waste gas generated by brick making by blending and burning sludge.

Drawings

FIG. 1 is a schematic structural diagram of a dry-wet combined desulfurization and dust removal system for waste gas from sludge-blended brick making in an embodiment.

FIG. 2 is a schematic structural diagram of a dry desulfurization dust removal system in the embodiment.

FIG. 3 is a schematic structural diagram of a wet desulfurization dust removal system in the embodiment.

In the figure, 1000, a dry desulfurization dust removal system; 1100. a lime bin; 1200. a dry desulfurization tower; 1300. a dust remover; 1400. an adsorber; 1500. a humidifying device; 1510. a water delivery pipeline; 1520. a compressed air conduit; 1530. an atomizer; 1600. a drying kiln; 2000. a wet desulfurization dust removal system; 2100. a pulping tank; 2200. a circulation tank; 2300. a wet desulfurization tower; 2310. a spraying device; 2311. a radial spray layer; 2312. a reverse spray layer; 2320. a dust and mist removing device; 2321. a wire mesh demister; 2322. a folded plate demister; 2323. a cyclone tube bundle demister; 2330. a backwashing device; 2400. a backwash tank; 2500. sintering kiln; 2600. a sedimentation tank; 3000. an exhaust gas collection system.

Detailed Description

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "coupled" to another element, it can be directly coupled to the other element or intervening elements may also be present.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Example 1

A factory which adopts sludge as raw material to manufacture environment-friendly bricks is selected, and the method of the invention is used for treating the generated waste gas. Specifically, the present embodiment is processed using the following system and method.

Firstly, the treatment and analysis of pollutants in the waste gas generated in the brick making process by blending and burning sludge.

The main raw materials of the sintered environment-friendly brick are paper-making sludge, printing and dyeing washing sludge, sludge of a municipal sewage treatment plant, sludge of a food and condiment factory, shale, fly ash, coal slag (furnace slag), residual mud of a construction site and the like. The production flow mainly comprises three steps: (1) drying, namely drying the sludge from the water content of 60% to 40% by using a biomass rotary kiln; (2) making bricks, mixing the materials according to a proper material ratio, and pressing the mixed raw materials into green bricks by using a brick making machine; (3) and (4) sintering, namely conveying the pressed green bricks into a tunnel kiln for sintering treatment to finish the firing of the environment-friendly bricks.

In the drying process, pollutants in the flue gas mainly come from the decomposition and volatilization of organic components in the flue gas generated by biomass combustion and sludge in the drying process, and the main components are a large amount of water vapor, dust and acidic gas (HF, HCl and SO)₂、SO₃、NO_XEtc.), CO, heavy metals (Cd, Ti, Sb, As, Pb, Cr, CO, Cu, Mn, Ni, etc.), dioxins, a large number of volatile organic compounds (methane, ethane, propane, propionic acid, etc.) and a part of inorganic pollutants (NH)₃、H₂S, HCN, etc.).

In the brick making process, pollutants in the smoke mainly come from raised dust and odor volatilization in the material conveying, mixing and pressing processes, the raised dust can be reduced in a closed conveying mode, ventilation in a workshop is enhanced, and plant deodorizers and other deodorization products are adopted as necessary.

In the sintering process, pollutants in the flue gas mainly come from the flue gas generated by burning fuel coal and sintering green bricks, and as a large amount of volatile organic compounds are volatilized in the drying process, the main components of the flue gas are a large amount of water vapor, dust and acid gases (HF and SO)₂、NO_XEtc.).

And secondly, a dry-wet method combined desulfurization and dust removal system for the sludge-doped brickmaking waste gas.

As shown in figure 1, the dry-wet combined desulfurization and dust removal system for the waste gas generated by brick making by blending combustion of sludge comprises: a dry desulfurization dust removal system 1000, a wet desulfurization dust removal system 2000 and a waste gas collecting system 3000. The dry desulfurization dust removal system 1000 is used for performing desulfurization dust removal treatment on waste gas generated in the drying kiln 1600, the wet desulfurization dust removal system 2000 is used for performing desulfurization dust removal treatment on waste gas generated in the sintering kiln 2500, the two waste gases after the treatment of the two systems are mixed and collected in the waste gas collecting system 3000, and the high-temperature waste gas is used for heating and whitening the low-temperature waste gas without performing additional whitening removal treatment. Specifically, the present invention achieves the above object by the following structure.

As shown in fig. 2, the dry desulfurization dust removal system 1000 comprises a lime bin 1100, a dry desulfurization tower 1200, a dust remover 1300 and an adsorber 1400 which are connected in sequence. The lower end of the dry desulfurization tower 1200 is provided with a first waste gas inlet and a material inlet, the first waste gas inlet is used for introducing waste gas into the drying kiln 1600, and the upper end of the dry desulfurization tower 1200 is provided with a first waste gas outlet. Lime bin 1100 is in communication with the feed inlet of dry desulfurization tower 1200 and provides an adsorbent (e.g., dry hydrated lime) to dry desulfurization tower 1200. In order to further improve the desulfurization effect, a humidifying device 1500 is further provided, and the humidifying device 1500 comprises an atomizer 1530, a water conveying pipeline 1510 for conveying water, and a compressed air pipeline 1520 for conveying compressed air. One end of the water pipe 1510 is communicated with the atomizer 1530, and the other end is communicated with the water storage bucket. One end of the compressed air pipe 1520 communicates with the atomizer 1530, and the other end communicates with a compressed air tank. The water and the compressed air are mixed in the atomizer 1530, and sprayed to form atomized water droplets, and the atomized water droplets are sprayed into the dry desulfurization tower 1200 through the nozzle of the atomizer 1530, which is directed downward, in the opposite direction to the rising direction of the exhaust gas. The atomized water droplets sprayed by the humidifying device 1500 can not only humidify the adsorbent, but also cool the exhaust gas. The desulfurized exhaust gas enters the dust collector 1300 for dust removal, the dust collector 1300 in the embodiment is a bag type dust collector, the bag type dust collector comprises a first unit dust collector, a second unit dust collector and a third unit dust collector which are connected in parallel, and the exhaust gas is shunted to each unit dust collector for filtering and dust removal after entering. Due to the vortex action, a single unit of dust catcher will trap a large amount of unreacted sorbent, which can be directed into the dry desulfurization tower 1200 for reuse. The adsorber 1400 is preferably an activated carbon adsorption tank for adsorbing a pollutant gas such as an odor gas.

In order to further improve the desulfurization efficiency, a venturi tube (not shown) is disposed at the bottom of the dry desulfurization tower 1200, and the venturi tube is vertically disposed, and an inlet thereof is communicated with the first waste gas inlet, and an outlet thereof is communicated with the material inlet. The pipe diameter of the middle part of the Venturi pipe is sharply reduced, the waste gas is accelerated at the position when rising, a strong internal turbulent airflow is formed, the absorbent at the upper end of the Venturi pipe is converged into the turbulent airflow, and the contact time of the absorbent and the absorbent is increased in the continuous upward and backflow processes of the turbulent airflow, so that the utilization rate of the absorbent and the desulfurization efficiency are improved.

As shown in fig. 3, the wet desulfurization and dust removal system 2000 includes a slurrying tank 2100, a circulation tank 2200, and a wet desulfurization tower 2300, which are connected in sequence. The lower extreme of wet flue gas desulfurization tower 2300 is equipped with the second waste gas entry, and the upper end of wet flue gas desulfurization tower 2300 is equipped with the second exhaust outlet, and wet flue gas desulfurization tower 2300 is equipped with spray set 2310 and dust removal defogging device 2320 from the second exhaust gas entry to the second exhaust outlet in proper order. The circulation tank 2200 is connected to a spray device 2310 to supply desulfurization liquid (e.g., lime slurry) to the spray device 2310 for wet desulfurization. The circulation tank 2200 is also connected to the bottom of the wet desulfurization tower 2300, and the sulfur slurry is recovered to the circulation tank 2200 to be reused. The sintering kiln 2500 is connected with the wet desulphurization tower 2300 through a flue, the inlet of the flue of the inlet tower is designed to enter in a downward cutting mode, the downward cutting angle is 10-15 degrees, and the entering of waste gas can be reducedThe flow speed in tower time prolongs the flow path and the retention time of the waste gas in the absorption tower. In order to reduce the load of the wet desulphurization tower 2300, a pre-spraying layer which is radially arranged can be arranged in the flue gas inlet into the tower, the angle between the pre-spraying layer and the flow direction of the pipeline is 90 degrees, the desulphurization slurry in the circulating pool 2200 is sprayed into the pipeline for primary desulphurization, and the SO of the flue gas inlet into the tower is reduced₂And (4) concentration.

To improve the desulfurization efficiency, the spray device 2310 includes at least three radial spray layers 2311 and one reverse spray layer 2312, for example: the spraying device 2310 is sequentially provided with a first radial spraying layer, a second radial spraying layer, a third radial spraying layer and a reverse spraying layer 2312 from bottom to top. The included angle between the spraying angle of the radial spraying layer 2311 and the inner tower wall is about 15 degrees, and the desulfurization liquid can drive the flue gas to rotate at high speed. The reverse spray layer 2312 sprays vertically downward with a spray area covering the inner cross section of the absorber. The flue gas is subjected to high-speed rotary cutting and reverse spraying to obtain desulfurized slurry, and gas-liquid phases continuously collide with the rotary cutting to be mutually crushed and further fully mixed. As the sulfur-containing flue gas moves at high speed in the desulfurization slurry in the form of ultrafine bubbles and is extruded and cut, the gas-liquid contact interface is continuously updated, the gas-liquid-solid mass transfer area is increased, the resistance of mass transfer is reduced, and the desulfurization efficiency is improved. The desulfurization circulating liquid and by-products after the desulfurization reaction flow to the circulating bath 2200 through the outlet at the bottom of the absorption column.

The dust and mist removing device 2320 includes at least one layer of wire mist eliminators 2321 and at least two layers of flap mist eliminators 2322 and/or swirl tube bundle mist eliminators 2323. The spiral-flow tube bundle demister comprises an upper orifice plate and a lower orifice plate, a plurality of vertically arranged tube bundles are arranged between the upper orifice plate and the lower orifice plate, a plurality of turbulent flow balls are arranged in the tube bundles, and the turbulent flow balls are solid turbulent flow balls and/or hollow turbulent flow balls. In this embodiment, dust removal defogging device 2320 includes from the screen mist eliminator 2321, folded plate mist eliminator 2322 and the cyclone tube bundle mist eliminator 2323 that set gradually down. The wire mesh mist eliminator 2321 can remove part of water vapor and particulate matter, and the flap mist eliminator 2322 and the swirling flow tube bundle mist eliminator 2323 can remove mist droplets and part of ultrafine dust, so that the exhaust gas meets the emission requirement.

In order to facilitate cleaning of the dedusting and demisting device 2320, backwashing devices 2330 are arranged above and below each layer of demister, the backwashing devices 2330 are backwashing spray pipes which are connected with the backwashing pool 2400, and the backwashing pool 2400 provides washing water for the backwashing spray pipes.

The wet desulphurization and dust removal system 2000 further comprises a sedimentation tank 2600, wherein the sedimentation tank 2600 is communicated with the bottom of the circulation tank 2200, materials at the bottom of the circulation tank 2200 can be transferred to the sedimentation tank 2600, and materials with low water content at the bottom after sedimentation can be prepared into dry slag for recycling.

The waste gas collecting system 3000 is a vertically arranged collecting pipeline, and the side wall of the collecting pipeline is provided with a first inlet communicated with the adsorber 1400, and is used for introducing waste gas treated by the dry desulfurization dust removal system 1000; the bottom of the collecting pipe is provided with a second inlet communicated with the wet desulphurization tower 2300 for introducing the waste gas treated by the wet desulphurization and dust removal system 2000. The manifold may be directly connected to the top of the wet desulfurization tower 2300. Preferably, the collecting pipeline and the wet desulphurization tower 2300 are of an integrated structure. The two waste gases after the split-flow treatment are mixed in a collecting pipeline, and the low-temperature waste gas (the temperature is about 55 ℃) after the wet desulphurization and dust removal is heated and whitened by utilizing the high-temperature waste gas (the temperature is about 80-100 ℃) after the semi-dry desulphurization and dust removal, so that the additional whitening removal treatment is not needed.

And thirdly, dry-wet combined desulfurization and dust removal process flow and parameter setting of the sludge-blended brick making waste gas.

1. Semi-dry desulfurization and dust removal method

And (3) introducing the waste gas in the brick making drying step into a dry desulfurization and dust removal system, desulfurizing by adopting a semidry method, and then performing bag-type dust removal.

The desulfurization step involves storage and transportation of an absorbent, a desulfurization tower, a humidification system, and the like. The waste gas enters a semi-dry desulfurization tower, a Venturi tube is arranged at the bottom of the semi-dry desulfurization tower, the waste gas is accelerated when flowing through the Venturi tube and is mixed with an absorbent (hydrated lime) and cooling spray, and the absorbent and SO in the waste gas₂To produce CaSO₃The cooling spray not only effectively controls the temperature of the flue gas, but also increases the content of moisture in the waste gas, thereby being beneficial to improving the desulfurization efficiency of the absorbent. The waste gas after being desulfurized and cooled is discharged from the top of the desulfurizing tower along with a large amount of solid particles and then enters a dust remover, wherein the waste gas isMost particles are separated, and part of particles return to the absorption tower through the absorbent recycling system and are recycled for many times to improve the use efficiency of the desulfurizer.

Important design performance parameters in the above desulfurization step are as follows: the molar ratio of calcium to sulfur is 1.4-2.0, the flow rate of the waste gas entering the dry-method desulfurizing tower is 4.0-5.0 m/s, and the flow rate of the humidifying material (namely water) is 1.2-2.4 m³The compressed air flow rate is 1.3-2.6 m³Min; the inner diameter of the absorption section is 1.4-2.2 m, the inner diameter of the throat of the Venturi tube with the height of 13.0-18.0 m is 200-260 mm, the height of the Venturi tube is 2.1-2.7 m, and the flow velocity of the throat is 45-65 m/s.

And in the dust removal step, three-stage dust removers, namely a first-stage dust remover, a second-stage dust remover and a third-stage dust remover which are connected in series are adopted. The existing pulse bag type dust collector is adopted in each stage of dust collector. The gas purification mode of the pulse bag type dust removal unit is an external filtration mode, and dust-containing gas enters each unit filter chamber through a flow guide pipe and passes through a flue gas flow guide device arranged in an ash hopper; because the vertical distance between the bottom of the bag and the upper opening of the air inlet is enough and reasonably clearance exists, airflow is distributed through proper flow guide and natural flow direction, and the airflow in the whole filter chamber is uniformly distributed; the particle dust in the dust-containing gas directly falls into the dust hopper after natural sedimentation separation, and the rest dust enters the middle box body filtering area along with the air flow under the guide of the flow guide system and is adsorbed on the outer surface of the filter bag. The filtered clean gas passes through the filter bag, passes through the upper box body and is exhausted by the exhaust pipe. The filtering wind speed is controlled to be 0.8m/min during dust removal.

The filter bag adopts compressed air to perform blowing ash removal, and the ash removal mechanism comprises an air bag, a blowing pipe, an electromagnetic pulse control valve and the like. And the top of the outlet of each row of filter bags in the filter chamber is provided with a blowing pipe, the lower side of the blowing pipe is provided with a blowing port right facing the center of the filter bag, and each blowing pipe is provided with a pulse valve and communicated with a compressed air bag. When the dust is cleaned, the electromagnetic valve opens the pulse valve, compressed air is sprayed to the filter bag through the nozzle and is injected into the filter bag together with ambient air injected by the compressed air, the filter bag is triggered to shake comprehensively, a back-blowing airflow effect from inside to outside is formed, dust attached to the outer surface of the filter bag is removed, and the purpose of cleaning dust is achieved.

Along with the progress of the filtering working condition, when the dust accumulated on the surface of the filter bag reaches a certain amount, the dust cleaning control device (differential pressure or timing or manual control) opens the electromagnetic pulse valves according to a set program for blowing, compressed air passes through each pulse valve in a very short time sequence, and air which is several times of the air jet volume is induced by the nozzles on the blowing pipe to enter the filter bag to form air waves, so that the filter bag generates sharp expansion and impact vibration from the bag opening to the bottom, a strong dust cleaning effect is caused, and dust on the filter bag is shaken off. The dust falling into the dust hopper is discharged through the dust discharging valve and then is output through the dust conveying system.

2. Wet desulfurizing and dust-removing method

The wet desulfurization process can adopt limestone, calcium oxide and calcium hydroxide as desulfurization absorbent, the absorbent is ground into powder and mixed with water to form absorption slurry. At present, wet desulphurization mainly adopts various forms of empty tower spraying, absorption slurry is contacted and mixed with flue gas in a spraying absorption tower, sulfur dioxide in the flue gas, calcium ions in the slurry and oxidation air blown into the slurry are subjected to chemical reaction and removed, and the final reaction product is gypsum.

And removing fine liquid drops from the desulfurized flue gas by a demister, and then discharging the flue gas into a wet chimney with an anticorrosive coating. And after the desulfurized gypsum slurry is dehydrated by the dehydrating device, part of the desulfurized gypsum slurry is recycled to the brick making process, and the surplus part of the desulfurized gypsum slurry is transported out of the factory for treatment. The absorption slurry is recycled, so that the utilization rate of the desulfurization absorbent is high.

The reaction equation involved in the desulfurization process is as follows:

SO₂+H₂O→H₂SO₃

Ca(OH)₂+H₂SO₃→CaSO₃·¹/₂H₂O+³/₂H₂O

CaSO₃·¹/₂H₂O+¹/₂H₂O+SO₂→Ca(HSO₃)₂

CaSO₃·¹/₂H₂O+¹/₂O₂+³/₂H₂O→CaSO₄·2H₂o (by-product)

The spray mass transfer mode in the tower combines a radial spray machine and a reverse spray machine, on one hand, radial atomization spray is used for capturing most of fine dust during desulfurization, and the dust removal capacity of the desulfurization tower is enhanced; on the other hand, two spraying modes are simultaneously used in the same tower body, and compared with a single spraying mode, the slurry circulation amount is remarkably reduced.

The desulfurized slurry is sent to a spraying system by a circulating pump, and the desulfurized components in the slurry and SO in the flue gas₂Fully mixing mass transfer reaction, returning to the tower bottom under the action of gravity, entering a desulfurization circulating pool, and performing automatic control recycling according to the process control of pH, liquid level and the like.

In order to ensure the uniform flow of the flue gas entering the tower of the two furnaces, the design of an inlet flue opening adopts a large inlet and low flow rate design; the inlet adopts the design of downward cutting inlet, the downward cutting angle is generally 10-15 degrees, so that the flue gas enters the desulfurizing tower in a downward cutting way at a lower speed, and the flow and the retention time of the flue gas in the desulfurizing tower are prolonged.

The high-speed turbulent flue gas collides with the absorbent sprayed by the spraying device, the flue gas is subjected to high-speed rotary cutting to freely fall the desulfurization slurry, and the gas phase and the liquid phase continuously collide with each other and are subjected to rotary cutting to be mutually crushed and further fully mixed. As the sulfur-containing flue gas moves at a high speed in the desulfurization slurry in a superfine bubble form and is extruded and cut, the gas-liquid interface is continuously updated, the concentration of sulfur-containing gas molecules continuously broken through a gas film and the concentration of the desulfurization slurry continuously broken through a liquid film are close to the concentration of a gas-liquid main body, the mass transfer resistance is reduced, and the gas-liquid-solid three phases carry out contact mass transfer with huge surface area and extremely small interface resistance.

According to the hydromechanics characteristics of the tower body, the nozzle groups and the flow of each nozzle are designed, so that not only can the uniform flow of the flue gas of the tower body be ensured, but also the violent gas-liquid countercurrent contact in the reaction can be ensured, the full mass transfer and heat transfer reaction can be carried out, and the desulfurization efficiency can be ensured to be more than 99%. The overall arrangement of the spraying layer increases the contact area and probability of slurry and gas, and ensures that the effective cross section (flue gas distribution cross section) of the whole tower body is covered by not less than 200%.

The folded plate demister is arranged at the top of the absorption tower and is used for separating the purified flue gasFog droplets and a part of very fine dust. Fog drops carried by outlets larger than 15 mu m and less than or equal to 75mg/Nm³(dry basis). The system is provided with a flushing and draining system for removing sediment of the demister, and can be automatically flushed and manually flushed during operation according to a given or variable program.

The demister is made of reinforced flame-retardant polypropylene and can bear high-speed water flow scouring, particularly high-speed water flow scouring caused by manual scouring. The demister washing water system can comprehensively wash the demister and avoid blockage of the demister. The spray ranges of adjacent nozzles should overlap partially to ensure 100% flushing effect. The pressure of the flush water should be monitored and controlled and the flush water header should be arranged so that each nozzle operates at substantially the average water pressure.

The main parameters of the three-phase turbulence barrel high-efficiency wet desulphurization tower are shown in the table 1.

TABLE 1 three-phase turbulence barrel high-efficiency wet-process desulfurization tower main parameters

Item	Unit of	Technical parameters
			Standard flue gas treatment	Nm³/h	150000
Temperature of flue gas in tower	℃	45
			Oxygen content of flue gas	％	19
Working condition flue gas treatment capacity	Am³/h	175000
			Inlet SO₂Measured concentration	mg/Nm³	500
Inlet SO₂Reduced concentration	mg/Nm³	750
			Outlet SO₂Measured concentration	mg/Nm³	67
Outlet SO₂Reduced concentration	mg/Nm³	35
			Design desulfurization efficiency	％	95.3
Total amount of circulating slurry	m³/h	1200
			Make up the liquid-gas ratio	L/Nm³	8
Actual operating liquid-to-gas ratio	L/Nm³	6
			Flow rate of flue gas	m/s	2.04
Residence time in the column	s	≥3
			Size of desulfurization absorption zone	m	Φ5.5m，H＝16m
Resistance of tower body	Pa	≤1000
			Circulating pump	Table (Ref. Table)	5(3 in 2 pieces)
Tower body material	-	Special glass fiber reinforced plastic
			Spray layer	Layer(s)	5(3 in 2 pieces)
Radial nozzle	An	18×3
			Reverse nozzle	An	24
Pipeline spray nozzle	An	4
			Demister	Layer(s)	2

The slurry circulating system comprises a circulating tank, a circulating pump (used for spraying and supplying liquid) and an oxidation system in the tank. The cycle system parameters are shown in table 2.

TABLE 2 technical parameters of the circulation system

After the gas-liquid in the desulfurizing tower is fully contacted and mass-transferred, when the technological control parameter is reached, the CaSO is contained in the desulfurized slurry₃·1/2H₂O、Ca(HSO₃)₂、CaSO₄And the incompletely reacted desulfurization slurry is sprayed by a circulating pump again in a circulating way and repeatedly reacts with the flue gas for many times. After multiple times of circulating absorption, the pH value of the desulfurized slurry is reduced, when the pH value is lower than a designed value, lime is supplemented by the lime packed in bags which is manually unpacked, the pH value of the circulating pool is increased, when the upper limit of the pH value of the process control is reached, the lime supplementation is stopped, and CaSO in the circulating liquid₃·1/2H₂The concentration of O is increased, the desulfurization capability is increased, and the desulfurization efficiency can be stably maintained at a higher level as long as the process parameters are properly controlled.

The oxidation system consists of an oxidation fan and an aeration pipeline. The oxidation fan is arranged near the circulating tank, and the aeration pipeline is inserted into the bottom of the circulating tank. The oxidation fan conveys air into the circulating tank through an aeration pipeline to oxidize calcium sulfite into calcium sulfate, the solubility of the calcium sulfate is low, the calcium sulfate is separated out from the original calcium sulfate dihydrate crystal seeds in the reaction tank, the crystals grow continuously, and when the gypsum reaches a certain concentration, the gypsum is discharged to a byproduct treatment system from the circulating tank.

A circulating tank: providing enough space for staying, circulating and oxidizing the circulating liquid;

circulating pump: pumping the circulating liquid into a desulfurizing tower through a spray pipe group, and carrying out mixed reaction with the flue gas; the number of start-stop of the circulating pump can be determined according to the actual working condition; each circulating pump corresponds to one or two layers of spraying pipe groups.

A pump-out pump: pumping the oxidized slurry to a brick making process for recycling;

an oxidation fan: blowing clean air into the circulating tank to forcibly oxidize the calcium sulfite into calcium sulfate which is easy to dehydrate; an aeration pipe set is matched in the circulating tank, so that air and circulating liquid are uniformly mixed, and the air utilization rate and the oxidation efficiency of byproducts are improved;

back flushing the pump: and sending the industrial water into a demister backwashing spray pipe group for backwashing at regular time, and flushing and cleaning the accumulated scale.

And fourthly, processing the result.

The dry-wet combined system is adopted to treat the blended-combustion sludge brick making, and indexes of various pollutants in the treated flue gas are as follows: the reduced concentration of the particles is less than or equal to 10mg/Nm³，SO₂The reduced concentration is less than or equal to 35mg/Nm³，NO_XThe guaranteed value of the discharge concentration is less than or equal to 200mg/Nm³(emission concentration converted to 18% baseline oxygen content). The treated indexes meet the national treatment standard of the waste gas generated by brick making by blending and burning sludge.

The dry-wet method combined system is adopted to treat the waste gas generated by brick making by using the co-combustion sludge, and the annual treatment of the waste gas is about 63000-144000 ten thousand Nm³A (50% -110% load), the required operating cost (including the cost of water and electricity, the cost of absorbent and the cost of operators) is about 65-80 ten thousand yuan (50% -110% load). Under the same exhaust gas treatment amount, the operation cost of wet desulphurization and dust removal needs about 150 and 170 ten thousand yuan (50-110% load). In contrast, the system of the present embodiment andthe method can save more than 50% of the operation cost every year, and has great economic benefit.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. The dry-wet combined desulfurization and dust removal method for the waste gas generated by making bricks by blending burned sludge is characterized in that a dry-wet combined desulfurization and dust removal system is adopted for desulfurization and dust removal, and the dry-wet combined desulfurization and dust removal system comprises:

2. The dry-method and wet-method combined desulfurization and dust removal method for waste gas generated in brick making by blending burned sludge as claimed in claim 1, wherein the waste gas collecting system is fixed above the wet-method desulfurization tower.

3. The dry-method and wet-method combined desulfurization and dust removal method for waste gas generated in brick making by blending combustion of sludge as claimed in claim 1, wherein the humidifying device comprises an atomizer, a water conveying pipeline and a compressed air pipeline, one end of the water conveying pipeline is communicated with the atomizer, the compressed air pipeline is communicated with the atomizer, and the atomizer is communicated with the dry-method desulfurization tower.

4. The dry-method and wet-method combined desulfurization and dust removal method for waste gas generated in brick making by blending burned sludge as claimed in claim 1, wherein the spraying device comprises at least three radial spraying layers and one reverse spraying layer.

5. The dry-method and wet-method combined desulfurization and dust removal method for waste gas generated in brick making by using co-combustion sludge as claimed in claim 1, wherein the dust and mist removal device comprises at least one layer of wire mesh mist eliminator, at least two layers of folded plate mist eliminators and/or cyclone tube bundle mist eliminators.

6. The dry-method and wet-method combined desulfurization and dust removal method for waste gas generated in brick making by co-firing sludge as claimed in claim 5, wherein the cyclone tube bundle demister comprises an upper orifice plate and a lower orifice plate, a vertically arranged tube bundle is arranged between the upper orifice plate and the lower orifice plate, and turbulence balls are arranged in the tube bundle.

7. The dry-method and wet-method combined desulfurization and dust removal method for waste gas generated in brick making by using co-combustion sludge as claimed in claim 5, wherein a back-washing device for washing a wire mesh demister, a folded plate demister or a cyclone tube bundle demister is further arranged in the wet desulfurization tower, and the back-washing device is connected with a back-washing tank.

8. The dry-method and wet-method combined desulfurization and dust removal method for waste gas generated in brick making by using co-fired sludge as claimed in claim 1, wherein in the step of treating the waste gas generated in the drying kiln, the molar ratio of calcium in the desulfurization material in the dry-method desulfurization tower to the waste gas in unit time is 1.4-2.0, the flow rate of the waste gas entering the desulfurization tower is 4.0-5.0 m/s, and the flow rate of the humidifying material is 1.2-2.4 m³The compressed air flow rate is 1.3-2.6 m³Min; the inner diameter of the absorption section of the dry desulfurization tower is 1.4-2.2 m, and the height is 13.0-18.0 m.

9. The dry-method and wet-method combined desulfurization and dust removal method for waste gas generated in brick making by using co-fired sludge as claimed in claim 8, wherein in the step of treating the waste gas generated in the drying kiln, the filtering air speed is 0.7-0.9 m/min during dust removal.

10. The dry-wet combined desulfurization and dust removal method for waste gas generated in brick making by blending burned sludge as claimed in claim 1, wherein the waste gas treated by the dry desulfurization and dust removal system in unit time accounts for more than 40% of the total treated waste gas.