JP5552815B2 - Tar recovery device - Google Patents

Description

  The present invention relates to a tar recovery apparatus.

  2. Description of the Related Art Conventionally, development of a gas generation facility that generates a gasification gas or a pyrolysis gas using a solid fuel such as coal, biomass, waste plastic, or various hydrated wastes as a fuel has been promoted.

  Generally, when the solid fuel is gasified or pyrolyzed at a low temperature (400 to 900 [° C.]) in a gasification furnace or a pyrolysis furnace, tar components are contained in the gasification gas and pyrolysis gas produced. The gasified gas and pyrolysis gas containing the tar component are condensed and misted when the temperature is lowered, so the gasification gas and pyrolysis gas are used as raw materials for chemical synthesis. In such cases, problems such as blockage of piping due to condensed tar, troubles in equipment, poisoning of the synthesis catalyst due to tar adhesion, etc. are caused in the purification process and chemical synthesis process on the downstream side. If tar itself is recovered, it can be used as a fuel or chemical raw material, so it is desirable that it can be recovered.

  In order to eliminate such problems and collect tar, conventionally, a plurality of stages of gasification gas or pyrolysis gas generated in the gasification furnace or pyrolysis furnace are provided in series in the gas flow direction. By sequentially introducing into a scrubber and performing gas cooling with the scrubber in stages, the high-boiling tars are sequentially recovered, and tars having different boiling points are separated and recovered.

  For example, Patent Document 1 shows a general technical level related to the tar recovery method as described above.

JP 2000-129269 A

  In the tar recovery method disclosed in Patent Document 1, the tar is separated by spraying cooling water on the gas introduced in the scrubber, and the tar is transferred to the drainage side together with the cooling water. The tar is recovered from the system by specific gravity separation or the like, but in reality, the condensed and misted tar is a fine mist of several [μm] or less, and one scrubber at each stage. According to the test conducted by the present inventor, the tar that can be removed by the present inventor is only about 50% of the total tar contained in the introduced gas, and the remaining tar mist that could not be removed is accompanied by the gas. Since it flows to the downstream side, not only recovery becomes difficult, but also the separation efficiency of tar species having different boiling points that should be recovered by the next-stage scrubber on the downstream side is lowered, Results to had the disadvantage that separation and recovery of tar per boiling point can not.

  In view of such circumstances, the present invention can prevent tar mist condensed in each scrubber from flowing downstream along with the gas, increasing the separation efficiency of tar species having different boiling points and increasing the tar for each boiling point. It is an object of the present invention to provide a tar recovery device that can reliably perform the separation and recovery.

The present invention provides a scrubber into which a tar-containing gas is introduced in a plurality of stages in series in the gas flow direction, and a tar recovery device that sequentially recovers from a high boiling point tar in each scrubber.
Wet dust collecting means disposed on the outlet side of each scrubber and collecting tar mist condensed in each scrubber ,
The wet dust collecting means is composed of a wet dust collecting screen,
The wet dust screen is:
A duct through which gas flows,
A nozzle disposed in the duct and spraying water;
A mesh screen plate in which a number of flat honeycomb-shaped gas permeation holes penetrating at an inclination angle of 30 to 60 ° with respect to the gas flow direction is formed in the duct so that the gas permeation hole has the same penetration direction. A dust collecting screen main body formed by laminating a plurality of layers with phases shifted by 90 ° sequentially in the gas flow direction by rotating about an axis extending in the flow direction;
The present invention relates to a tar recovery device.

  According to the tar recovery apparatus of the present invention, tar mist condensed in each scrubber can be prevented from flowing downstream with gas, and the separation efficiency of tar species having different boiling points can be improved to increase the tar for each boiling point. It is possible to achieve an excellent effect that the separation and recovery of the water can be reliably performed.

It is a whole schematic block diagram which shows the reference example of the tar collection | recovery apparatus of this invention. It is a whole schematic block diagram which shows the Example of the tar collection | recovery apparatus of this invention. It is an enlarged plan view which shows the wet dust collection screen used for the Example of the tar collection | recovery apparatus of this invention. It is IV-IV sectional drawing of FIG. It is VV sectional drawing of FIG.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a reference example of the tar recovery apparatus of the present invention. 1 is a gasification gas at a low temperature (400 to 900 [° C.]) from solid fuel such as coal, biomass, waste plastic, or various hydrated wastes. The generated gasification furnace 2 is a cyclone that removes soot and dust from the gasification gas generated in the gasification furnace 1, and 3 is a temperature at which tar does not condense the gasification gas from which soot and dust has been removed by the cyclone 2 (300 A scrubber 5 that condenses tar by cooling the gasification gas as the tar-containing gas recovered by heat in the heat exchanger 3. In a tar recovery device in which a plurality of stages (three stages in the example in the figure) are provided in series in the gas flow direction, and each scrubber 5 sequentially collects high-boiling tars, each scrubber 5 is provided on the outlet side thereof. 5 is obtained the wet electrostatic precipitator 7 as a wet dust collector unit 6 for collecting the condensed tar mist disposed in.

  The wet electrostatic precipitator 7 has a configuration in which a nozzle 7b for spraying water and a dust collecting electrode 7c are disposed in a casing 7a through which gasified gas is circulated.

  The tar-containing wastewater separated and recovered from the gasification gas in the scrubber 5 and the wet electrostatic precipitator 7 is collected in a decanter 9 for each stage, and the tar separated from the tar-containing wastewater in the decanter 9 is recovered in tar. While recovered in the tank 10, the water from which the tar has been separated is sprayed from the nozzle 5 a in the scrubber 5 and the nozzle 7 b in the wet electrostatic precipitator 7 as circulating water by driving the pump 11.

  Further, the dust removed from the gasification gas by the cyclone 2 is recovered in the dust recovery tank 4.

Next, the operation of the reference example will be described.

  In the gasification furnace 1, the gasification gas as a tar-containing gas generated at a low temperature (400 to 900 [° C.]) from solid fuel such as biomass, waste plastic, or various hydrated wastes is dusted by the cyclone 2. Is removed and cooled in the heat exchanger 3 to a temperature at which tar does not condense (300 to 500 [° C.]) and heat recovery is performed, and then introduced into the first-stage scrubber 5.

  The tar-containing gas introduced into the first-stage scrubber 5 is cooled by water sprayed from the nozzle 5a to separate high-boiling tar, and the tar is added to the decanter 9 together with water as tar-containing wastewater. On the other hand, the tar mist condensed by the high boiling point tar and flowing into the downstream side with the gas flows to the downstream side, but is cooled by the water sprayed from the nozzle 7b in the first-stage wet electrostatic precipitator 7. 90% or more of the tar mist is collected by the discharge from the dust collecting electrode 7c, and the tar mist collected in the first-stage wet electrostatic precipitator 7 is collected together with water as tar-containing wastewater. The tar-containing wastewater collected in the decanter 9 is separated from the tar that settles heavier than water or tar that floats lighter than water. The water from which the tar is separated while being collected in the tank 10 is circulated by driving the pump 11, and the nozzle 5a in the first stage scrubber 5 and the nozzle in the first stage wet electrostatic precipitator 7. Sprayed from 7b.

  The gasification gas in which most of the tar mist is collected and removed in the first-stage wet electrostatic precipitator 7 has dropped to about 120 [° C.], and the second-stage scrubber 5 continues. To be introduced.

  The tar-containing gas introduced into the second-stage scrubber 5 is cooled by water sprayed from the nozzle 5a to separate tar having a lower boiling point than the tar separated by the first-stage scrubber 5, While the tar is collected in the decanter 9 together with water as tar-containing wastewater, the tar mist, which is condensed by mist having a lower boiling point than the tar separated in the first-stage scrubber 5, is accompanied by gas. In the second stage wet electrostatic precipitator 7, about 90% or more of tar mist is collected by the discharge from the dust collecting electrode 7c while being cooled by the water sprayed from the nozzle 7b. The tar mist collected in the second-stage wet electrostatic precipitator 7 is collected together with water into the decanter 9 as tar-containing wastewater, and the tar-containing waste collected in the decanter 9 is collected. The tar that settles heavier than water or the tar that floats lighter than water is separated by specific gravity and collected in the tar collection tank 10, and the water from which the tar has been separated is recycled as the circulating water by driving the pump 11. It sprays from the nozzle 5a in the second stage scrubber 5 and the nozzle 7b in the second stage wet electrostatic precipitator 7.

  The gasification gas in which most of the tar mist has been collected and removed in the second stage wet electrostatic precipitator 7 has dropped to about 75 [° C.], and the third stage scrubber 5 continues. To be introduced.

  The tar-containing gas introduced into the third-stage scrubber 5 is cooled by water sprayed from the nozzle 5a, and tar having a lower boiling point than that of the tar separated by the second-stage scrubber 5 is separated, While the tar is collected in the decanter 9 together with water as tar-containing wastewater, the tar mist that is condensed and mist is formed by the gas having a boiling point lower than that of the tar separated by the second stage scrubber 5 is accompanied by the gas. In the third stage wet electrostatic precipitator 7, about 90% or more of the tar mist is collected by the discharge from the dust collecting electrode 7c while being cooled by the water sprayed from the nozzle 7b. The tar mist collected in the third-stage wet electrostatic precipitator 7 is collected together with water into the decanter 9 as tar-containing wastewater, and the tar-containing waste collected in the decanter 9 is collected. The tar that settles heavier than water or the tar that floats lighter than water is separated by specific gravity and collected in the tar collection tank 10. Spraying is performed from the nozzle 5a in the third-stage scrubber 5 and the nozzle 7b in the third-stage wet electrostatic precipitator 7.

  The gasification gas in which most of the tar mist is collected and removed in the third-stage wet electrostatic precipitator 7 has a temperature drop of about 40 [° C.], and is used as a raw material for chemical synthesis. However, it is sent to the downstream purification process or chemical synthesis process, but there is no concern about problems such as piping blockage due to tar, troubles in equipment, poisoning of the synthesis catalyst due to tar adhesion, and the like.

  Thus, unlike the tar recovery method disclosed in Patent Document 1, each wet electrostatic precipitator 7 prevents tar mist that could not be removed by each scrubber 5 from flowing downstream along with the gas. In addition, it is possible to recover most of the amount, and the separation efficiency of tar species having different boiling points to be recovered in the downstream downstream scrubber 5 is improved. Thus, the separation and recovery are surely performed.

  In this way, it is possible to prevent the tar mist condensed in each scrubber 5 from flowing to the downstream side accompanying the gas, and to improve the separation efficiency of tar species having different boiling points, thereby reliably separating and recovering tar for each boiling point. obtain.

2-5 is an embodiment of a tar recovery system of the present invention, in the figure, portions denoted by the same reference numerals as in FIG. 1 represents the same matter, the basic configuration is reference shown in FIG. 1 Although similar to the example , the feature of this embodiment is that the wet dust collecting means 6 is constituted by a wet dust collecting screen 8 instead of the wet electric dust collector 7, as shown in FIGS. is there.

  The wet dust collection screen 8 is provided with a nozzle 8b for spraying water in a duct 8a through which gas is circulated, and a dust collection screen body 8c having a function of collision and separation of tar mist from the gas flow. In the example of FIG. 2, two sets of the nozzle 8b and the dust collecting screen body 8c are provided at a required interval in the gas flow direction in the duct 8a. It is not limited to two sets.

  As shown in FIGS. 3 to 5, the dust collection screen main body 8c is formed by laminating a plurality of mesh screen plates 8e made of a metal thin plate having a large number of flat honeycomb-shaped gas permeation holes 8d. A flat honeycomb-shaped gas permeation hole 8d formed in the mesh screen plate 8e is formed by a convex surface 8f and a concave surface 8g that are continuous in a wavy shape, and penetrates at a required inclination angle θ with respect to the gas flow direction. In this way, the mesh screen plate 8e having a large number of holes formed so as to have the same penetration direction of the gas permeation hole 8d is rotated about an axis extending in the gas flow direction to sequentially turn 90 ° in the gas flow direction. A plurality of sheets are stacked with a phase shift.

  The inclination angle θ of the gas permeation hole 8d is in the range of 30 to 60 °, which is effective in increasing the efficiency of collecting tar mist from the gas flow by collision separation, while the plurality of layers are stacked. The mesh screen plates 8e may be brought into contact with each other, but for example, if the layers are laminated with a gap of about 1 to 1.5 [mm], the adhesion resistance is lost, so that the pressure loss is reduced accordingly. In addition, it is convenient for cleaning the attached tar.

  Further, the thickness of the mesh screen plate 8e is, for example, about 0.15 [mm] in the case of an aluminum alloy, and the gas permeation holes 8d adjacent to each other in a row extending in the left-right direction in FIG. The dimension A between the centers of the gas permeation holes 8d adjacent to each other in the vertically extending row in FIG. 3 is about 5.5 [mm]. The dimension C between the gas permeation holes 8d adjacent to each other in the oblique direction can be about 2.25 [mm], and the opening angle α of the gas permeation hole 8d can be about 110 °.

  Furthermore, if the number of the mesh screen plates 8e is four, for example, the second mesh screen plate 8e is 90 ° with respect to the first mesh screen plate 8e, and the third mesh screen. The plate 8e is 180 °, and the fourth mesh screen plate 8e is 270 °, each of which is out of phase about the axis extending in the gas flow direction. In FIG. 3, the first mesh screen plate 8e is indicated by a solid line, and the second mesh screen plate 8e is indicated by an imaginary line.

Next, the operation of the above embodiment will be described.

  In the gasification furnace 1, the gasification gas as a tar-containing gas generated at a low temperature (400 to 900 [° C.]) from solid fuel such as biomass, waste plastic, or various hydrated wastes is dusted by the cyclone 2. Is removed and cooled in the heat exchanger 3 to a temperature at which tar does not condense (300 to 500 [° C.]) and heat recovery is performed, and then introduced into the first-stage scrubber 5.

  The tar-containing gas introduced into the first-stage scrubber 5 is cooled by water sprayed from the nozzle 5a to separate high-boiling tar, and the tar is added to the decanter 9 together with water as tar-containing wastewater. On the other hand, the tar mist condensed and misted by the high boiling point tar flows to the downstream side along with the gas, but is caused by the water sprayed from the nozzle 8b in the first-stage wet dust collecting screen 8. About 90% or more of the tar mist is collected by collision separation by the mesh screen plate 8e stacked while being cooled, and the tar mist collected in the wet dust collecting screen 8 in the first stage is collected together with water. The tar-containing wastewater collected in the decanter 9 is collected as tar-containing wastewater, and the tar-containing wastewater collected in the decanter 9 settles heavier than water or floats lighter than water. The tar is separated by specific gravity and collected in the tar collecting tank 10, and the water from which the tar is separated is circulated by driving the pump 11, and the nozzle 5 a in the first stage scrubber 5 and the first stage. It sprays from the nozzle 8b in the wet-type dust collection screen 8 of eyes.

  Here, the tar-containing gas that enters the dust collection screen body 8c of the wet dust collection screen 8 enters the gas transmission hole 8d of the first mesh screen plate 8e with an inclination angle θ of 30 to 60 °, The gas permeation hole 8d of the mesh screen plate 8e of the first sheet penetrates with an inclination angle θ of 30 to 60 ° while changing the direction to the direction of 90 ° rotation about the axis extending in the gas flow direction, Entry into the gas permeation hole 8d of the third mesh screen plate 8e with an inclination angle θ of 30 to 60 ° while changing the direction further turning 90 ° around the axis extending in the gas flow direction. Then, with respect to the gas permeation hole 8d of the fourth mesh screen plate 8e, the inclination angle θ of 30 to 60 ° is changed while the direction is further turned 90 ° around the axis extending in the gas flow direction. Will invade with Therefore, the gas flow flows in a spiral shape, and the tar mist is collected in the three-dimensional space of the entire dust collecting screen body 8c by collision separation.

  The gasification gas in which most of the tar mist has been collected and removed by the first-stage wet dust collection screen 8 has dropped to about 120 [° C.], and the subsequent second-stage scrubber 5 is introduced.

  The tar-containing gas introduced into the second-stage scrubber 5 is cooled by water sprayed from the nozzle 5a to separate tar having a lower boiling point than the tar separated by the first-stage scrubber 5, While the tar is collected in the decanter 9 together with water as tar-containing wastewater, the tar mist, which is condensed by mist having a lower boiling point than the tar separated in the first-stage scrubber 5, is accompanied by gas. In the second stage wet dust collection screen 8, the tar mist is about 90% or more due to the collision separation by the mesh screen plate 8e laminated in plural while being cooled by the water sprayed from the nozzle 8b. And the tar mist collected in the second stage wet dust collecting screen 8 is collected in a decanter 9 together with water as tar-containing waste water, The tar-containing wastewater collected in the decanter 9 is collected in the tar collection tank 10 by separating the tar that is heavier than water and settles or the tar that floats lighter than water and is collected in the tar collection tank 10. 11 is sprayed as circulating water from the nozzle 5a in the second-stage scrubber 5 and the nozzle 8b in the second-stage wet dust collecting screen 8.

  The gasification gas in which most of the tar mist is collected and removed in the second-stage wet dust collection screen 8 has dropped to about 75 [° C.], and the subsequent third-stage scrubber 5 is introduced.

  The tar-containing gas introduced into the third-stage scrubber 5 is cooled by water sprayed from the nozzle 5a, and tar having a lower boiling point than that of the tar separated by the second-stage scrubber 5 is separated, While the tar is collected in the decanter 9 together with water as tar-containing wastewater, the tar mist that is condensed and mist is formed by the gas having a boiling point lower than that of the tar separated by the second stage scrubber 5 is accompanied by the gas. In the third stage wet dust collection screen 8, the tar mist is about 90% or more due to the collision separation by the mesh screen plate 8e laminated in plural while being cooled by the water sprayed from the nozzle 8b. Is collected, and tar mist collected in the wet dust collecting screen 8 of the third stage is collected in a decanter 9 together with water as tar-containing waste water, The tar-containing wastewater collected in the decanter 9 is collected in the tar collection tank 10 by separating the tar that is heavier than water and settles or the tar that floats lighter than water and is collected in the tar collection tank 10. 11 is sprayed as circulating water from the nozzle 5a in the third stage scrubber 5 and the nozzle 8b in the third stage wet dust collecting screen 8.

  The gasification gas from which most of the tar mist has been collected and removed by the wet dust collection screen 8 in the third stage has been lowered to about 40 [° C.], and is used as a chemical synthesis raw material or the like. At that time, it is sent to a purification process or chemical synthesis process on the downstream side, but there is no concern that problems such as blockage of piping due to tar, troubles in equipment, poisoning of the synthesis catalyst due to tar adhesion, etc. will be caused.

  Thus, unlike the tar recovery method disclosed in Patent Document 1, each wet dust collecting screen 8 causes tar mist that could not be removed by each scrubber 5 to flow downstream with the gas. It is prevented, and most of it can be recovered, and the separation efficiency of tar species having different boiling points to be recovered by the downstream scrubber 5 is also improved. Tar separation and recovery will be performed reliably.

  In addition, if gasified gas is mixed with air due to leakage, there is a risk of ignition if there is an ignition source, so it is necessary to be careful in handling the wet gas collection screen 8 as described above. The use is effective in preventing ignition by eliminating the ignition source.

Thus, in the embodiment shown in FIG. 2, as in the reference example shown in FIG. 1, tar mist condensed in each scrubber 5 can be prevented from flowing downstream along with the gas, and tars having different boiling points. The separation efficiency of seeds can be increased, and tar can be separated and recovered for each boiling point.

  The tar recovery apparatus of the present invention is not limited to the above-described embodiments, but is not limited to the recovery of tar from gasified gas as a tar-containing gas that is gasified in a gasification furnace. Applicable to tar recovery from tar-containing gas such as pyrolysis gas that is pyrolyzed in a furnace. The number of scrubber and wet dust collecting means is not limited to three but any number of stages It goes without saying that various modifications can be made without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Gasification furnace 2 Cyclone 3 Heat exchanger 5 Scrubber 5a Nozzle 6 Wet dust collection means 7 Wet electric dust collector 7a Casing 7b Nozzle 7c Dust collection electrode 8 Wet dust collection screen 8a Duct 8b Nozzle 8c Dust collection screen body 8d Gas permeation hole 8e Mesh screen plate 8f Convex surface 8g Concave surface 9 Decanter 10 Tar recovery tank θ Tilt angle

Claims (1)

In a tar recovery apparatus in which a plurality of scrubbers into which a tar-containing gas is introduced are provided in series in the gas flow direction, and each scrubber is recovered in order from a high boiling point tar,
Wet dust collecting means disposed on the outlet side of each scrubber and collecting tar mist condensed in each scrubber ,
The wet dust collecting means is composed of a wet dust collecting screen,
The wet dust screen is:
A duct through which gas flows,
A nozzle disposed in the duct and spraying water;
A mesh screen plate in which a number of flat honeycomb-shaped gas permeation holes penetrating at an inclination angle of 30 to 60 ° with respect to the gas flow direction is formed in the duct so that the gas permeation hole has the same penetration direction. A dust collecting screen main body formed by laminating a plurality of layers with phases shifted by 90 ° sequentially in the gas flow direction by rotating about an axis extending in the flow direction;
Tar recovery apparatus characterized by having a.

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