JP2005279420A - Treatment equipment of tar-containing exhaust gas and tar removing method in treatment of exhaust gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique for preventing the adhesion of tar easily adaptable even to existing incineration equipment without installing great equipment while preventing a sharp increase in pressure loss. <P>SOLUTION: This treatment equipment of a tar-containing exhaust gas is provided with a tar saponifying and removing device 4 for directly bringing a saponifying liquid becoming an alkali solution into contact with the tar containing exhaust gas to saponify tar in the exhaust gas to remove the same and an inertial dust collector 5 having an impingement wall on which the exhaust gas impinges and an impingement wall adhesion preventing liquid supply means for supplying a tar adhesion preventing liquid to the surface of the impingement wall. The tar-containing exhaust gas is supplied to the tar saponifying and removing device 4 to saponify tar to remove the same before supplied to the inertial dust collector 5 not only to remove tar but also to separate and remove mist. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exhaust gas treatment technology suitably used in incineration facilities such as sewage sludge and industrial waste, and in particular, a technology for preventing problems caused by tar content in exhaust gas, for example, blockage and failure of equipment and flue. About.

  Conventionally, sewage is collected in a sewage treatment plant and incinerated or landfilled through a concentration and dehydration process. In recent years, from the viewpoint of energy saving measures and environmental measures, effective use such as hot water using exhaust gas retained heat discharged at the time of incineration, exhaust heat boiler use, and the like has been carried out.

  From such a viewpoint, in drying sewage sludge before incineration, the incineration exhaust gas is used as a heat source, and a method of directly contacting the sludge containing organic components with the exhaust gas is generally adopted. .

  However, in such a dry method by direct contact, there is a problem that a part of organic components is vaporized and mixed in the exhaust gas, and adheres as tar in the subsequent induction fan, exhaust gas reuse facility and its piping. . In this case, a great deal of labor is required for the tar removal work, and the entire equipment must be stopped for the removal work, which causes problems in equipment operation.

  Against this background, several proposals have been made for a method for removing tar from exhaust gas. Specifically, after exhaust gas is cooled using a wet scrubber and tar is removed, a method of collecting tar and moisture remaining in the exhaust gas with a wet electrostatic precipitator (see Patent Document 1), or before incineration Proposed is a method (see Patent Document 2) in which an exhaust gas is passed through a waste product to remove tar.

However, wet electrostatic precipitators require a relatively large installation space and are difficult to apply to existing facilities. The electric dust collector also has a problem that the equipment cost and running cost are high. Furthermore, electrostatic precipitators are not applicable to flammable gases. On the other hand, the method of passing the exhaust gas through the waste before putting it into the incinerator is advantageous in terms of cost, but if the exhaust gas is passed through the waste, it causes a great pressure loss and exhausts the exhaust gas. Therefore, it is necessary to greatly increase the fan power necessary for this.
Japanese Patent Laid-Open No. 11-21565 JP-A-10-118614

  Then, the main subject of this invention is providing the tar adhesion prevention technique which can be applied easily also to the existing incineration equipment, without installing a large installation, preventing the significant increase in pressure loss.

The present invention that has solved the above problems is as follows.
<Invention of Claim 1>
In the treatment equipment for exhaust gas containing tar,
A pipe adhesion prevention liquid supply means is provided for supplying tar adhesion prevention liquid to the inner surface of the pipe through which the exhaust gas flows.
A tar-containing exhaust gas treatment facility characterized in that the exhaust gas is circulated in a state where the tar adhesion preventing liquid is present on the inner surface of the pipe.

(Function and effect)
In this way, when the tar adhesion preventing liquid is supplied to the inner surface of the piping through which the exhaust gas is circulated, such as piping connecting equipment in the exhaust gas treatment facility, tar is precipitated on the surface of the tar adhesion preventing liquid, Does not adhere to the inner surface of the pipe and is washed away together with the prevention liquid. As can be seen from this, the invention described in this section is intended to positively collect and eliminate the tar precipitated in the pipe. In this method, almost no pressure loss occurs as in the conventional method of passing through waste, and it can be easily applied to existing incineration facilities without installing a large amount of facilities. In particular, there is also an advantage that it can be partially applied to a portion where the amount of adhered tar is large in existing exhaust gas treatment equipment.

<Invention of Claim 2>
In the treatment equipment for exhaust gas containing tar,
As the tar removing means, an inertia dust collector having a collision wall with which exhaust gas collides and a collision wall adhesion preventing liquid supply means for supplying a tar adhesion preventing liquid to the surface of the collision wall is provided.
A tar-containing exhaust gas treatment facility configured to cause the exhaust gas to collide with the collision wall in a state where the anti-adhesion liquid is present on the collision wall surface of the inertia dust collector.

(Function and effect)
The present inventors examined various combinations of dust collectors, but obtained knowledge that it is difficult to solve the above problems in terms of tar removal capability, pressure loss, applicability to existing facilities, compactness, and the like. . For this reason, as a result of further earnest research, as described above, by configuring the exhaust gas to collide with the collision wall in the state where the tar adhesion preventing liquid is present on the collision wall surface of the inertia dust collector, the tar removal capability, It has been found that pressure loss, applicability to existing facilities, compactness, etc. can all be solved in a well-balanced manner, and has led to the present invention.

  Inertia dust collectors were thought to be unusable in the past because tar would directly adhere and accumulate on the collision wall when used as a tar removal means in an exhaust gas treatment facility. Since tar does not deposit directly on the collision wall surface, long-term continuous operation is possible. The inertia dust collector has the advantage that the pressure loss is the second smallest after the electrostatic dust collector and gravity sedimentation, and the performance is not deteriorated by the tar adhesion preventing liquid. Furthermore, it goes without saying that it is excellent in applicability to existing facilities and compactness.

  In addition, the “inertia dust collector” in the present specification means an inertia dust collector that substantially uses an inertia effect, and does not include a scrubber or an electric dust collector.

<Invention of Claim 3>
In the treatment equipment for exhaust gas containing tar,
A tar-containing exhaust gas treatment facility comprising a tar saponification removal device for removing tar by saponifying the tar in the exhaust gas by directly contacting a saponification solution made of an alkaline solution with the exhaust gas as means for removing tar.

(Function and effect)
As described above, the present inventors have studied novel methods other than the above special inertia dust collection based on the idea that simply combining general-purpose technologies cannot provide a satisfactory technology that can solve the above-described problems. It has been developed and has led to the invention described in this section.

  That is, the invention described in this section utilizes the fact that when the tar contained in the exhaust gas is brought into direct contact with an alkaline solution typified by caustic soda, it becomes a soap solid by a saponification reaction. When such a chemical reaction is used, unlike the case where the precipitation of tar is promoted, the tar content in the exhaust gas can be positively extracted, so that efficient tar removal is possible. Further, since there is a degree of freedom in the contact form, it is easy to adopt a contact form that is compact and has little pressure loss (for example, the form described in the next section).

<Invention of Claim 4>
The tar saponification removal apparatus is;
A contact container and a separation container;
The contact vessel has an exhaust gas inlet and a treated product outlet, a collision wall provided therebetween, and a saponification liquid supply means for supplying the saponification liquid to the surface of the collision wall.
The treated product outlet of the contact container communicates with the separation container,
The separation container has an exhaust gas outlet, a solid-liquid outlet, and a washing water supply means,
The exhaust gas containing tar is introduced from the exhaust gas inlet of the contact container, and the exhaust gas is brought into direct contact with the saponification liquid supplied from the saponification liquid supply means to saponify the tar content and supply it into the separation container. Inside, the cleaning water is supplied by the cleaning water supply means, the gas component is discharged from the exhaust gas outlet, and the solid-liquid component is discharged through the solid-liquid outlet.
The tar-containing exhaust gas treatment facility according to claim 3.

(Function and effect)
The invention described in this section is a preferred form of tar removal by saponification described above, and adopts the same form as the above-described inertia dust collector as the contact form of the exhaust gas and the saponification solution, By separating them into separate containers, processing with less pressure loss becomes possible. Moreover, in the separation container, washing water is supplied to discharge the saponified tar (soap), so that a smooth continuous operation is possible.

<Invention of Claim 5>
In the treatment equipment for tar-containing exhaust gas,
While having a treatment device with exhaust gas cooling,
An exhaust gas fan that distributes exhaust gas downstream to the upstream side of the most upstream processing apparatus is provided, and a tar-containing exhaust gas treatment that does not have a fan for distributing exhaust gas downstream thereof Facility.

(Function and effect)
In the conventional exhaust gas treatment facility, an induction fan for circulating the exhaust gas is installed between the processing devices or at the most downstream position. In such an installation, for example, if a treatment device with exhaust gas cooling, such as a wet scrubber, is installed on the upstream side for early tar removal, tar adheres to the attracting fan on the downstream side, so frequent maintenance is required. May be necessary or failure may occur.

  With respect to such a tar adhesion problem, the invention described in this section aims to solve the tar adhesion problem easily and effectively from the viewpoint of tar removal. In the invention described in this section, since the tar passes through the fan before cooling, the tar hardly adheres to the fan.

<Invention of Claim 6>
In the treatment equipment for exhaust gas containing tar,
A tar saponification removing device that directly contacts a saponification solution made of an alkaline solution and exhaust gas, and saponifies and removes tar in the exhaust gas,
An inertia dust collector having a collision wall with which the exhaust gas collides, and a collision wall adhesion preventing liquid supply means for supplying a tar adhesion preventing liquid to the surface of the collision wall;
Exhaust gas containing tar was supplied to the tar saponification removing device and saponified and removed, and then supplied to the inertia dust collector to remove tar and separate and remove mist.
A tar-containing exhaust gas treatment facility characterized by that.

(Function and effect)
When the tar saponification removal apparatus and the inertia dust collector of the present invention are used in combination in this order, it is preferable because the tar content missed in the tar saponification removal apparatus and the mist mixed in the exhaust gas accompanying the saponification removal can be removed by the inertia dust collector. . In particular, it is suitable when the moisture concentration in the exhaust gas after the inertia dust collector is desired to be kept low, for example, when a heat exchanger or a furnace is installed after the inertia dust collector.

<Invention of Claim 7>
The tar according to claim 6, wherein a wet scrubber is provided on the upstream side of the tar saponification removal device, and the exhaust gas containing the tar is washed and collected by the wet scrubber and then supplied to the tar saponification removal device. Waste gas treatment equipment.

(Function and effect)
The wet scrubber tends to have higher removal efficiency as the tar concentration is higher. On the other hand, since the tar saponification removing apparatus is based on a chemical reaction, it exhibits a sufficient removing ability even when the tar concentration is low. Therefore, as described in this section, by using a wet scrubber upstream of the tar saponification removal device, it is possible to efficiently treat the exhaust gas containing a high amount of tar, and then remove the low concentration residual tar with the tar saponification removal device. If it comprises, more effective tar removal will be attained.

<Invention of Claim 8>
The tar-containing exhaust gas treatment facility according to claim 7, further comprising a pipe adhesion preventing liquid supply means for supplying a tar adhesion preventing liquid to the inner surfaces of the inlet side pipe and the outlet side pipe of the wet scrubber.

(Function and effect)
When a wet scrubber is installed, the exhaust gas temperature is lowered in the outlet pipe, and tar is likely to adhere to the inner surface of the pipe. Therefore, as described in this section, it is possible to effectively prevent tar adhesion on the inner surface of the pipe by providing the pipe adhesion preventing liquid supply means on the inner surface of the outlet side pipe of the wet scrubber. In consideration of the cooling precipitation effect of tar in the wet scrubber, if the exhaust gas temperature at the inlet of the wet scrubber is somewhat higher than the tar precipitation temperature, it is lowered in advance to near the tar precipitation temperature or below the tar precipitation temperature. As a result, the tar deposition efficiency in the wet scrubber is increased, and the tar removal capability is improved. Therefore, as described in this section, the exhaust gas supplied to the wet scrubber can be pre-cooled by providing the pipe adhesion prevention liquid supply means on the inlet and outlet pipe inner surfaces of the wet scrubber. The removal ability can be increased. Of course, tar adhesion on the inner surface of the inlet pipe can be effectively prevented.

<Invention of Claim 9>
The tar-containing exhaust gas treatment facility according to claim 8, wherein an exhaust gas fan for sending exhaust gas is provided upstream of the pipe adhesion preventing liquid supply means, and a fan for circulating the exhaust gas is not provided downstream thereof.

(Function and effect)
By installing the exhaust gas fan at such a position, tar adhesion to the fan can be effectively prevented in the same manner as in the fifth aspect of the invention.

<Invention of Claim 10>
In the method for treating exhaust gas containing tar,
When circulating the exhaust gas through a pipe, the exhaust gas is circulated in a state where a tar adhesion preventing liquid is present on the inner surface of the pipe.

(Function and effect)
The same effects as those of the first aspect of the invention can be achieved.

<Invention of Claim 11>
In the method for treating exhaust gas containing tar,
Using an inertia dust collector having a collision wall with which the exhaust gas collides, and a collision wall adhesion prevention liquid supply means for supplying tar adhesion prevention liquid to the collision wall surface,
A treatment of a tar-containing exhaust gas characterized by causing the exhaust gas to collide with the collision wall in a state where the adhesion preventing liquid is present on the collision wall surface of the inertia dust collector, to deposit tar, and separating and removing the precipitated tar. Method.

(Function and effect)
The same effects as those of the second aspect of the invention can be achieved.

<Invention of Claim 12>
In the method for treating exhaust gas containing tar,
A method for treating a tar-containing exhaust gas, characterized in that a cleaning liquid containing caustic soda is brought into direct contact with the exhaust gas to saponify and remove the tar in the exhaust gas.

(Function and effect)
The same effects as those of the third aspect of the invention can be achieved.

<Invention of Claim 13>
In the method for treating tar-containing exhaust gas,
The exhaust gas fan that circulates the exhaust gas downstream is provided further upstream than the processing apparatus that involves cooling the exhaust gas that exists on the most upstream side, and the fan for circulating the exhaust gas is not provided downstream of the processing apparatus. A method for treating a tar-containing exhaust gas, characterized in that exhaust gas is circulated only by the exhaust gas fan.

(Function and effect)
The same effects as those of the invention of claim 5 are achieved.

  As described above, the present invention can be easily applied to existing incineration facilities without installing a large amount of equipment while preventing a significant increase in pressure loss. Can also be applied to a wide range of equipment).

  Hereinafter, an embodiment of the present invention will be described in detail based on an application example of sewage sludge to a drying facility. FIG. 1 shows a front part in an example of drying equipment for sewage sludge. The sewage sludge is supplied to the dryer 20, directly contacted with the hot air supplied from the hot air furnace 21, dried by the amount of heat held by the exhaust gas (hot air drying type), and then supplied to an incinerator (not shown) for incineration and melting. Or it is landfilled after being taken off-site. After removing the dust using a dust collector 22 such as a cyclone, the exhaust gas is supplied to the deodorizing furnace in the subsequent stage shown in FIG. 2, and the odor content in the exhaust gas is heated and deodorized.

  In this way, in the method of direct contact with hot air and sewage sludge, a part of the organic matter is vaporized and mixed in the exhaust gas, which precipitates in the downstream equipment and adheres as tar, causing equipment clogging / failure. . In order to solve this problem, the present invention is applied in the example shown in FIG. The exhaust gas from the dust collector 22 is attracted and sent out by the exhaust gas fan 1 and is first supplied to the venturi scrubber 2 and the spray tower scrubber 3 for cooling and tar removal. In this example, two types of wet scrubbers 2 and 3 are combined to form a two-stage process, but the present invention is not limited to this, and a single-stage or three-stage or more structure may be employed. There are no particular restrictions on the type of scrubber, other than a filling type with a built-in packing for increasing the contact area between gas and liquid, a porous plate type that forms a water film on the perforated plate, and allows gas to pass therethrough. Any of a spray type, a venturi type and the like can be used. However, as a result of experiments conducted by the present inventors, when the tar concentration in the exhaust gas is high, the precipitation of the tar is promoted not only by cooling with the cleaning liquid but also by changes in the exhaust gas flow rate. Accordingly, as shown in the figure, first, tar is deposited and removed by cooling and changing the flow velocity using the Venturi scrubber 2, and then the tar is removed by cooling with a scrubber having a high degree of cooling, such as the spray tower scrubber 3. It is desirable to deposit and remove.

  The degree of cooling by the wet scrubbers 2 and 3 can be determined as appropriate. For example, when exhaust gas having an inlet temperature of 200 to 300 ° C is processed, the outlet temperature is preferably 40 to 50 ° C.

  The exhaust gas from which tar has been removed by the wet scrubbers 2 and 3 is then subjected to removal of residual tar by the tar saponification removal apparatus 4 of the present invention. As the tar saponification removal device 4, for example, a saponification solution is used as a scrubber cleaning solution as long as the saponification solution consisting of an alkaline solution represented by caustic soda is brought into direct contact with the exhaust gas to saponify and remove the tar in the exhaust gas. Alternatively, a simple form in which exhaust gas is blown into the saponification solution in the container may be employed. As the saponification solution, caustic soda water can be suitably used, and various additives can be added as necessary. The concentration of caustic soda water is preferably about 3 to 10%.

  When the tar content in the exhaust gas is saponified, the tar becomes a solid content (soap) and can be easily separated from the exhaust gas. Furthermore, because of the chemical reaction, the tar can be efficiently separated and removed even if the tar concentration in the exhaust gas is low. However, since tar becomes a solid content, handling for separation and discharge becomes slightly difficult. Therefore, the present invention proposes a tar saponification removal apparatus 4 shown in FIG. 3 as a solution to this problem. This tar saponification removal apparatus 4 is a functional separation type of a contact container 41 and a separation container 42. The contact vessel 41 has a vertically long shape, has an exhaust gas inlet 41i at the upper end, has a treated product outlet 41x at the lower end, has a collision wall 41w therebetween, and further saponified liquid on the surface of the collision wall. In order to supply, it has saponification liquid supply nozzle 41n spaced apart above the collision wall. The contact container 41 can be made of resin or metal. As the collision wall 41w provided inside, a mesh-like member made of metal, resin, or the like is preferably used. The mesh member may be punched metal, expanded metal or filter cloth in which fine holes are formed in the plate. However, from the viewpoint of maintenance and ease of replacement when closed, a wire mesh or pyroscreen or its It is desirable to use a combination.

  On the other hand, the separation container 42 has a vertically long cylindrical shape, and the treatment product outlet pipe 41p of the contact container is inserted coaxially with respect to the container central axis x1 from the upper end portion to the substantially central portion, and the exhaust gas outlet 42g is disposed on the side surface of the upper end portion. And a liquid-liquid outlet 42s in the lower part, and a washing water nozzle 42n for supplying washing water is provided in the upper part of the container 42. In the preferred embodiment, as shown in the cross-sectional view of FIG. 4, the direction of the central axis x2 of the exhaust gas outlet 42g is directed to an eccentric position with respect to the central axis x1 in the vertical direction of the container, thereby The exhaust gas discharged from the lower end of the object outlet pipe 42g rises around the exhaust pipe 42g and is swirled in the process toward the exhaust gas outlet 42g.

  In the present apparatus 4, exhaust gas containing tar is introduced from the exhaust gas inlet 41i of the contact vessel 41, and this exhaust gas is brought into direct contact with the saponification liquid sprayed from the saponification liquid nozzle 41n in the air or on the surface of the collision wall 41w. The Thereby, the tar content in the exhaust gas causes a saponification reaction with caustic soda. The saponification solution is preferably supplied continuously, but may be configured to be supplied intermittently as necessary. In particular, when the collision wall 41w is a mesh member, the exhaust gas, the saponification solution, and the saponification solution are controlled by designing the member hole diameter and the number of holes and controlling the supply of the saponification solution so that a water film is formed on the surface of the mesh member. This is preferable because of improving the contact efficiency.

  Solid content and exhaust gas generated by saponification are supplied into the separation container 42, and the exhaust gas is discharged from an exhaust gas outlet 42 g at the top of the container 42. At this time, in the form shown in FIG. 4, a swirl flow due to the exhaust gas is generated in the separation container 42, and the exhaust gas and the solid-liquid component are favorably separated by the centrifugal force and the inertial force. On the other hand, the solid (soap) is discharged through the solid-liquid outlet 41s. Characteristically, water is sprayed from the washing water nozzle 42n in the upper part of the separation container 42, and the solid content remaining in the separation container 42 is discharged from the solid-liquid outlet 41s while being dissolved by this water. The spraying of water may be intermittent, but is preferably continuous.

  The treatment of the discharged solid-liquid component may be designed as appropriate. However, as shown in the figure, a storage tank 43 for discharging the liquid component by overflow or the like is provided, and the solid-liquid component from the separation container 42 is provided to this storage tank 43. It is preferable to be configured to discharge the gas. In this case, the solid content is dissolved in water in the storage tank 43 and the liquid content is mainly discharged, so that the subsequent handling becomes easy. The liquid discharged from the storage tank 43 can be drained using the drainage means of the scrubber 3 by supplying it to a used cleaning water storage section (not shown) provided in the scrubber 3. This method can be used even if the scrubber 3 is of a type that circulates and uses cleaning water.

  Exhaust gas exiting the wet scrubbers 2 and 3 and the tar saponification removal device 4 contains a large amount of moisture, and is not suitable for subsequent processing where low moisture is desired, such as preheating and heating deodorization described later. . Needless to say, it is more preferable if the tar content can be further reduced. Therefore, in this example, the residual tar and mist are removed from the exhaust gas from which the residual tar has been removed by the tar saponification removing device 4 by the inertia dust collector 5 of the present invention. The inertia dust collector 5 of the present invention has the same basic principle as the contact container 41 described above, but it is necessary to prevent mist from being mixed while removing residual tar and mist. For this reason, for example, as shown in FIG. 3, the supply port 52 is provided at the one end portion in the longitudinal direction of the horizontally long container 51, the other discharge port 53 is provided, and the collision walls 54, 55, and 56 are provided therebetween. A form can be adopted. Mixing mist in the horizontal direction in the horizontally long container 51 can reduce mist mixing. In particular, in the illustrated example, the collision walls 54, 55, 56 are provided in three stages, and the upstream two stages are provided with nozzles 57, 58 for spraying a tar adhesion preventing liquid such as water on the entry side and the exit side, respectively. The tar removal and adhesion prevention function is prioritized (mist removal is also performed), and the final stage is configured to prioritize the mist removal function without providing a spray nozzle for the adhesion prevention liquid. It is preferable to appropriately determine the number of steps of the collision wall in consideration of pressure loss and the removal state of tar, and usually 3 to 5 steps are preferable. The collision walls 54, 55, and 56 are preferably folded plate types, but are not limited to this, and may be a type in which a bent portion of the pipe is a collision wall.

  Thus, the tar in the exhaust gas is sufficiently removed. This example is a treatment of dry exhaust gas from sewage sludge. Since the exhaust gas contains odorous components such as hydrogen sulfide and methyl mercaptan, the exhaust gas from which tar has been removed is deodorized by the indirect heat exchanger 6 in order to remove this. After preheating by heat exchange with the furnace exhaust gas, the heat is supplied to the deodorizing furnace 7, and after deodorizing by heating, it is discharged from the chimney 8.

  On the other hand, no matter what tar removal device is used, not all of them can be removed at once, and there is a problem that deposited tar is unavoidably adhered to the inner surface of the exhaust gas circulation pipe in the facility. Therefore, the present invention also proposes a pipe adhesion preventing liquid supply means for supplying a tar adhesion preventing liquid to the inner surface of the pipe. Specifically, as shown in FIG. 2, it is simple and preferable to provide spray nozzles 12 and 13 for spraying an anti-adhesion liquid such as water toward the downstream side in pipes 10 and 11 through which exhaust gas flows. . Thereby, since the adhesion preventing liquid sprayed from the spray nozzles 12 and 13 uniformly wets the inside of the pipes 10 and 11, even when tar is deposited, it is difficult to adhere to the inner surface. In addition, since the exhaust gas is cooled by contact with the anti-adhesion liquid in the pipes 10 and 11 and tar is precipitated and trapped in the exhaust gas, it also has a function as a tar removal device.

  The number and shape of the spray nozzles 12 and 13 can be appropriately adopted according to the installation position, the amount of exhaust gas, and the amount of tar adhesion. The spraying of the anti-adhesion liquid may be intermittent, but it is preferable to perform the spraying continuously from the viewpoint of the anti-adhesion effect and the tar supplement effect.

  The installation location of the spray nozzles 12 and 13 is not limited as long as the exhaust gas circulates in the pipe, but tar adhesion to the inner surface of the pipe is more likely to occur as the tar concentration is higher and the exhaust gas temperature is lower. It is preferable to provide a processing apparatus that performs processing involving cooling of the exhaust gas positioned, for example, in the outlet piping 11 of the wet scrubbers 2 and 3 as shown in the figure (either the inlet side or the outlet side may be used, in which case It is preferable to provide the outlet side pipe 11).

  In the illustrated embodiment, the spray nozzle 12 is also provided in the inlet side pipe 10 of the wet scrubber 12. Of course, tar is prevented from adhering to the pipe here, but this is not intended for the main purpose. It is as follows. In other words, the spray nozzle is provided in the inlet side pipe 10 of the wet scrubber 12 because the exhaust gas is preliminarily cooled to near the tar deposition temperature or below the tar deposition temperature, so This is intended to remarkably improve the tar precipitation efficiency and thus the tar removal efficiency.

  Furthermore, the fan 1 for distribute | circulating waste gas can be mentioned to one of the equipment which should be considered most important in preventing tar adhesion. When tar adheres to such a physical drive device, there is a risk of noise generation, failure, or destruction, and internal cleaning is difficult. Therefore, when it is possible to sufficiently remove tar, it is preferable to arrange it at the downstream side of the most downstream tar removing device 5, but in the present invention, the idea is changed so that a large amount of tar is contained in the exhaust gas. The exhaust gas fan 1 for circulating the exhaust gas downstream is provided at the position where it is difficult to deposit, that is, the upstream side of the processing device 12 accompanied by the cooling of the exhaust gas existing on the most upstream side, and the exhaust gas is distributed downstream thereof. It is also proposed not to provide a fan for this purpose. In the illustrated example, since the upstream side of the wet scrubbers 2 and 3 is provided with the spray nozzle 12 for the anti-adhesion liquid in the pipe 10, this is the most upstream processing apparatus, and the exhaust gas fan 1 is provided on the upstream side, and the downstream side There are no fans at all. In this case, the temperature of the exhaust gas passing through the fan is higher than the tar deposition temperature, and the tar is difficult to deposit, so that the deposition of the deposited tar in the fan 1 is effectively prevented.

<Others>
(B) In the above embodiment, all of the present invention is applied in combination, but it goes without saying that a part thereof can be omitted or a part can be replaced by a known technique within the scope of the present invention. Absent.

(B) The filtered water generated in the sewage treatment plant can be used as the water used for the anti-adhesion liquid, the washing water and the caustic soda water in the above embodiment. Thereby, a large amount of water can be supplied without cost. Of course, even when used for exhaust gas treatment of other equipment, treated water discharged from the equipment or nearby equipment can be used.

<Tar saponification removal experiment>
102 g of tar recovered from the sewage sludge treatment facility was placed in a container installed in the electric furnace and heated to 200 to 240 ° C., and the exhaust gas was supplied to a container containing 160 ml of 5% strength aqueous sodium hydroxide solution. The experiment was continued until the tar residue in the furnace was 37.0 g. A large amount of soap solids were generated in the container. The tar removal rate was calculated by taking into account the caustic soda water container weight before and after the end of the experiment and the caustic soda use weight, and the result was 83%.

<Tar removal experiment using inertia dust collector>
102 g of tar recovered from the sewage sludge treatment facility is placed in a container installed in the electric furnace and heated to 200 to 240 ° C., and the exhaust gas is supplied to the inertia dust collector 5 having the configuration shown in FIG. The experiment was continued until 37.0 g of residue remained. In addition, water was supplied from the nozzles 57 and 58 of the inertia dust collector 5 at a rate of 90 liters / minute, the tar content in the waste water was measured, and the tar removal rate was calculated. As a result, it was 56%.

<Experiment related to tar adhesion in piping>
102 g of tar recovered from the sewage sludge treatment facility is put in a container installed in an electric furnace and heated to 200 to 240 ° C., and the exhaust gas is put into a pipe (length 4 m, inner diameter 350 mm) where a spray nozzle is installed. The experiment was continued until the tar residue in the furnace reached 37.0 g.

  First, when an experiment was conducted without spraying water from the spray nozzle, precipitated tar adhered to the pipe. Then, when water was sprayed at a rate of 5 liters / minute from the spray nozzle, tar did not adhere to the piping. Moreover, the waste water from piping was acquired, tar content was measured, and the tar removal rate was calculated, and as a result, it was 67%.

<Experiment regarding fan installation position>
102 g of tar recovered from the sewage sludge treatment facility is placed in a container installed in an electric furnace and heated to 200 to 240 ° C., and the exhaust gas (about 200 ° C.) is passed through a wet scrubber (exit temperature about 40 ° C.). It was attracted by an exhaust gas fan and continued until the tar residue in the furnace reached 37.0 g. As a result, precipitated tar adhered to the exhaust gas fan.

  Then, after supplying exhaust gas directly to the fan without going through the wet scrubber, it was supplied to the wet scrubber. Others were the same as above. In this case, no deposit tar was observed in the exhaust gas fan.

  The present invention is suitable for the treatment of dry exhaust gas from sewage sludge, but it can be used for a wide range of applications such as treatment of exhaust gas accompanying drying, incineration, or melting of various wastes as long as it can treat tar. Is applicable.

It is a front | former flow figure of a sewage sludge processing equipment. It is a flowchart of an exhaust gas treatment facility. It is a flowchart of the principal part. It is a cross-sectional view of a separation container.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fan, 2 ... Venturi type scrubber, 3 ... Spray tower type scrubber, 4 ... Tar saponification removal device, 5 ... Complete dust collector, 6 ... Indirect heat exchanger, 7 ... Deodorizing furnace, 8 ... Chimney, 10, 11 ... Piping , 12, 13 ... spray nozzles.

Claims (13)

In the treatment equipment for exhaust gas containing tar,
A pipe adhesion prevention liquid supply means is provided for supplying tar adhesion prevention liquid to the inner surface of the pipe through which the exhaust gas flows.
A tar-containing exhaust gas treatment facility characterized in that the exhaust gas is circulated in a state where the tar adhesion preventing liquid is present on the inner surface of the pipe. In the treatment equipment for exhaust gas containing tar,
As the tar removing means, an inertia dust collector having a collision wall with which exhaust gas collides and a collision wall adhesion preventing liquid supply means for supplying a tar adhesion preventing liquid to the surface of the collision wall is provided.
A tar-containing exhaust gas treatment facility configured to cause the exhaust gas to collide with the collision wall in a state where the anti-adhesion liquid is present on the collision wall surface of the inertia dust collector. In the treatment equipment for exhaust gas containing tar,
A tar-containing exhaust gas treatment facility comprising a tar saponification removal device for removing tar by saponifying the tar in the exhaust gas by directly contacting a saponification solution made of an alkaline solution with the exhaust gas as means for removing tar. The tar saponification removal apparatus is;
A contact container and a separation container;
The contact vessel has an exhaust gas inlet and a treated product outlet, a collision wall provided therebetween, and a saponification liquid supply means for supplying the saponification liquid to the surface of the collision wall.
The treated product outlet of the contact container communicates with the separation container,
The separation container has an exhaust gas outlet, a solid-liquid outlet, and a washing water supply means,
The exhaust gas containing tar is introduced from the exhaust gas inlet of the contact container, and the exhaust gas is brought into direct contact with the saponification liquid supplied from the saponification liquid supply means to saponify the tar content and supply it into the separation container. Inside, the cleaning water is supplied by the cleaning water supply means, the gas component is discharged from the exhaust gas outlet, and the solid-liquid component is discharged through the solid-liquid outlet.
The tar-containing exhaust gas treatment facility according to claim 3. In the treatment equipment for tar-containing exhaust gas,
While having a treatment device with exhaust gas cooling,
An exhaust gas fan that distributes exhaust gas downstream to the upstream side of the most upstream processing apparatus is provided, and a tar-containing exhaust gas treatment that does not have a fan for distributing exhaust gas downstream thereof Facility. In the treatment equipment for exhaust gas containing tar,
A tar saponification removing device that directly contacts a saponification solution made of an alkaline solution and exhaust gas, and saponifies and removes tar in the exhaust gas,
An inertia dust collector having a collision wall with which the exhaust gas collides, and a collision wall adhesion preventing liquid supply means for supplying a tar adhesion preventing liquid to the surface of the collision wall;
Exhaust gas containing tar was supplied to the tar saponification removal apparatus and saponified and removed, and then supplied to the inertia dust collector to remove tar and separate and remove mist.
A tar-containing exhaust gas treatment facility characterized by that.   The tar according to claim 6, wherein a wet scrubber is provided on the upstream side of the tar saponification removal device, and the exhaust gas containing the tar is washed and collected by the wet scrubber and then supplied to the tar saponification removal device. Waste gas treatment equipment.   The tar-containing exhaust gas treatment facility according to claim 7, further comprising a pipe adhesion preventing liquid supply means for supplying a tar adhesion preventing liquid to the inner surfaces of the inlet side pipe and the outlet side pipe of the wet scrubber.   The tar-containing exhaust gas treatment facility according to claim 8, wherein an exhaust gas fan for sending exhaust gas is provided upstream of the pipe adhesion preventing liquid supply means, and a fan for circulating the exhaust gas is not provided downstream thereof. In the method for treating exhaust gas containing tar,
When circulating the exhaust gas through a pipe, the exhaust gas is circulated in a state where a tar adhesion preventing liquid is present on the inner surface of the pipe. In the method for treating exhaust gas containing tar,
Using an inertia dust collector having a collision wall with which the exhaust gas collides, and a collision wall adhesion prevention liquid supply means for supplying tar adhesion prevention liquid to the collision wall surface,
A treatment of a tar-containing exhaust gas characterized by causing the exhaust gas to collide with the collision wall in a state where the adhesion preventing liquid is present on the collision wall surface of the inertia dust collector, to deposit tar, and separating and removing the precipitated tar. Method. In the method for treating exhaust gas containing tar,
A method for treating a tar-containing exhaust gas, characterized in that a cleaning liquid containing caustic soda is brought into direct contact with the exhaust gas to saponify and remove the tar in the exhaust gas. In the method for treating tar-containing exhaust gas,
The exhaust gas fan that circulates the exhaust gas downstream is provided further upstream than the processing apparatus that involves cooling the exhaust gas that exists on the most upstream side, and the fan for circulating the exhaust gas is not provided downstream of the processing apparatus. A method for treating a tar-containing exhaust gas, characterized in that exhaust gas is circulated only by the exhaust gas fan.

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