JP2007225223A - Pyrolysis gas treating method and its device for highly hydrous organic matter carbonizing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pyrolysis gas treating device for a highly hydrous organic matter carbonizing system complete combustion accompanied by the reduction of an NOx amount while maintaining a low fuel consumption rate by minimizing the use of assist fuel in combustion in a cracked gas burning furnace for pyrolysis gas after carbonizing in a carbonization furnace. <P>SOLUTION: Cracked gas produced from a highly hydrous organic matter in the carbonization furnace is introduced into the cracked gas burning furnace, a primary input of one part of dry exhaust gas after a drying process is carried out and primary combustion air is supplied to carry out a combustion process in a reducing atmosphere, secondary air is supplied to the combustion gas in the reducing atmosphere to carry out a combustion process in an oxidizing atmosphere, and a secondary input of dry exhaust gas of the combustion gas in the oxidizing atmosphere is carried out to carry out a final combustion process. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a method and apparatus for treating pyrolysis gas in a carbonization treatment system for treating sludge generated in a sewage treatment plant, food processing residue, livestock manure and other high water content organic matter.

In order to carbonize an organic substance containing high moisture represented by sewage sludge, the organic substance containing moisture as a raw material is generally dried and then carbonized in a carbonization furnace.
Here, as a heat source for the carbonization treatment, combustion exhaust gas obtained by burning the pyrolysis gas generated by the carbonization treatment in a cracked gas combustion furnace is used.
One of the pyrolysis gas treatment method and apparatus therefor of a high water content organic carbonization treatment system that suppresses the generation of NOx during combustion in the cracking gas combustion furnace is disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2005-200511) relating to the application of the present applicant. No. 199157) is provided.

FIG. 3 is a system diagram of a carbonization apparatus for high water content organic matter in the present invention.
In FIG. 3, this carbonization apparatus mainly includes a dehydrator 10 for dewatering sewage sludge, a drying furnace 20 for directly drying the sewage sludge with hot air, and an external heating type for carbonizing the dried sewage sludge. A rotary kiln type carbonization furnace 1, a combustion furnace 40 that mainly burns pyrolysis gas generated in the carbonization furnace 1, and a combustion furnace 50 that sends heated gas to the carbonization furnace 1 are configured.

The dehydrator 10 and the drying furnace 20 are connected by a line 110, the drying furnace 20 and the carbonization furnace 1 are connected by a line 21, and the drying furnace 20 and the combustion furnace 40 are connected via a circulating gas preheater 22. Are connected by a line 23.
The inside of the carbonization furnace 1 and the combustion furnace 40 are connected by a line 31 that is a pipe of pyrolysis gas generated in the carbonization furnace 1. The line 31 is provided with a cyclone 32 for separating and removing carbides from the pyrolysis gas. A line 33 and a line 34 for discharging the carbide 6 are respectively provided at the bottom of the cyclone 32 and the carbide outlet of the carbonization furnace 1.

The combustion furnace 40 and the drying furnace 20 are connected by a line 43 for supplying the combustion exhaust gas from the combustion furnace 40 as a drying gas. The line 43 branches to a line 44 and a line 45, and the gas flow path from the line 45 passing through the inside of the circulating gas preheater 22 merges with the line 37. Thereafter, the line 37 is sequentially connected to the air preheater 38 and the exhaust gas. It is configured as a pipe connecting the processing device 8 and the chimney 17.
The combustion furnace 40 is provided with a fan 48 so that combustion air can be sent into the combustion furnace 40 by the fan 48. The combustion furnace 40 includes combustion air from the fan 48, pyrolysis gas that has passed through the cyclone 32, dry exhaust gas after drying treatment in the drying furnace 20, and LNG (natural gas) or heavy oil. An auxiliary fuel composed of fossil fuel such as the like is supplied, and the pyrolysis gas is combusted.
The combustion furnace 50 is supplied with gas circulated through a line 53 as combustion air, and preheated air and auxiliary fuel from a line 61.

When carbonizing sludge using this high water content organic carbonization apparatus, first, sewage sludge is introduced into the dehydrator 10 and dehydrated until the water content of the sewage sludge becomes about 80%.
Next, the dewatered sewage sludge is sent to the drying furnace 20. In the drying furnace 20, the sludge is dried until the water content is about 30%. Drying in the drying furnace 20 is performed by bringing combustion exhaust gas introduced from the line 44 into direct contact with sludge. In addition, the combustion exhaust gas more than the amount necessary for drying is sent to the line 45 system. The dried sludge is introduced into the carbonization furnace 1 via the line 21.

In the carbonization furnace 1, the sludge is heated to about 300 to 600 ° C. in an oxygen-deficient atmosphere to perform carbonization, thereby generating pyrolysis gas and carbide 6 that is a solid fuel. The pyrolysis gas is introduced into the combustion furnace 40 through a line 31 and burns as described later.
In the carbonization furnace 1, auxiliary fuel is combusted in the combustion furnace 50 with combustion air from the line 61 and the circulation line 53, and the resulting heated gas is passed through the line 51 to the outer cylinder of the carbonization furnace 1. Supply by indirect heating without direct contact with sludge.
Note that the air from the line 61 is heated by heat exchange with the exhaust gas in the air preheater 38.

In the combustion furnace 40, a two-stage combustion process is performed.
In the first stage combustion section 40a of the combustion furnace 40, the pyrolysis gas is burned in a high-temperature reducing atmosphere at 900 to 1100 ° C. using combustion air together with auxiliary fuel at an air ratio <1.0. NH ₃ is decomposed, N ₂ O is decomposed, and NOx is reduced. Next, the pyrolysis gas is guided to the second stage combustion unit 40b, and in the first stage combustion unit 40b, combustion air is blown and burned in a low-temperature oxidizing atmosphere of 850 to 1000 ° C. with an air ratio> 1.0, Unburned gas is burned completely.

JP 2005-199157 A

In the high water content organic matter carbonization processing system in the invention of Patent Document 1 (Japanese Patent Application Laid-Open No. 2005-199157), in the combustion furnace 40 for combustion treatment of pyrolysis gas, the carbonization treatment process in the carbonization furnace 1 and the drying furnace 20 are used. Due to NH ₃ generated in the drying process, NOx derived from the oxidation of NH ₃ is easily generated during combustion in the combustion furnace 40.
As a combustion method for suppressing the conversion of NH ₃ -containing gas to NOx, low-NOx combustion by high-temperature reduction combustion using auxiliary fuel made of fossil fuel is effective. In this case, a large amount of auxiliary fuel is required. As a result, the fuel consumption rate of the auxiliary fuel is increased, and there is room for improvement in this respect.

  The present invention has been made in view of such a situation, and an object of the present invention is to minimize the use of auxiliary fuel for combustion in a cracked gas combustion furnace of pyrolysis gas after carbonization treatment in a carbonization furnace. An object of the present invention is to provide a pyrolysis gas treatment apparatus for a high water content organic matter carbonization treatment system that realizes complete combustion with a reduction in the amount of NOx while keeping the fuel consumption rate low.

  In order to solve the above-described problems of the prior art, the present invention performs a drying process on a high water content organic substance in a drying apparatus, carbonizes the high water content organic substance after the drying process in a carbonization furnace, and performs the carbonization process. A pyrolysis gas treatment method for a high water content organic carbonization processing system for combustion treatment of pyrolysis gas generated by the above, wherein the pyrolysis gas generated in the carbonization furnace is introduced into the cracking gas combustion furnace, and the cracking gas combustion In the furnace, a part of the dry exhaust gas after the drying process in the drying apparatus is first charged and the primary combustion air is supplied to perform a combustion process in a reducing atmosphere. Next combustion air is supplied to perform combustion processing in an oxidizing atmosphere, and then the dry exhaust gas is secondarily introduced into the combustion gas in this oxidizing atmosphere to perform final combustion processing. ).

In the above invention, the following configuration is preferable.
(1) In the final combustion process, the dry exhaust gas is introduced into the combustion gas in a plurality of stages, and both are combusted at a high temperature (claim 2).
(2) 10-30% of the dry exhaust gas input to the cracked gas combustion furnace is the primary input gas amount, and 70-90% of the dry exhaust gas is the secondary input gas amount (claim) Item 3).
(3) The primary combustion air and the secondary combustion air are air preheated by carbonization exhaust gas discharged after carbonization in the carbonization furnace by an air preheater, and the primary combustion air and secondary combustion air are subjected to the primary amount by an air amount adjusting means. The ratio of the supply air amount of the combustion air and the secondary combustion air is adjusted and supplied to the cracked gas combustion furnace (claim 4).

The invention of the apparatus for carrying out the pyrolysis gas treatment method is as follows:
High moisture content organic matter carbonization treatment which dries the high moisture content organic matter with a drying device, carbonizes the moisture content organic matter after passing through the drying treatment in a carbonization furnace, and burns the pyrolysis gas generated by the carbonization treatment In the pyrolysis gas treatment device of the system, a pyrolysis gas inlet for introducing the pyrolysis gas generated in the carbonization furnace, and a multistage dry exhaust gas into which the dry exhaust gas after the drying treatment in the drying device is introduced A cracked gas combustion furnace having an inlet, a plurality of stages of combustion air inlets for introducing combustion air, and a combustion exhaust gas outlet for sending combustion exhaust gas; A gas inlet is provided on the most upstream side so that the pyrolysis gas can flow in the longitudinal direction from the pyrolysis gas inlet to the combustion exhaust gas outlet, and one of the plurality of stages of the dried exhaust gas inlet is Combustion air introduction The combustion chamber in the reducing atmosphere of the pyrolysis gas can be opened by opening the upstream side of the furnace, the other dry exhaust gas inlet is opened downstream of the combustion air inlet, and the furnace after the combustion The internal gas is configured to be combustible with the combustion air and the dry exhaust gas (Claim 5).

  In the present invention, preferably, the cracked gas combustion furnace has the primary air inlet among the pyrolyzed gas inlet and the plurality of stages of combustion air inlets positioned along the flow direction of the pyrolyzed gas. Upstream, one of the plurality of stages of the dried exhaust gas inlets, the secondary air inlet of the plurality of stages of combustion air inlets, the other of the plurality of stages of the dried exhaust gas inlets, and the combustion exhaust gas feed It is comprised with the cylindrical body which arrange | positioned the exit along the longitudinal direction (Claim 6).

According to the present invention, the cracked gas combustion furnace is divided into a pyrolysis gas inlet into which the pyrolysis gas generated in the carbonization furnace is introduced and a multi-stage drying into which the dried exhaust gas after the drying treatment in the drying apparatus is introduced. An exhaust gas inlet, a plurality of stages of combustion air inlets through which combustion air is introduced, and a combustion exhaust gas outlet for sending the combustion exhaust gas are provided (claims 5 and 6), and the cracked gas combustion is performed. A part of the dry exhaust gas (preferably 10 to 30% of the dry exhaust gas: claim 3) after the drying treatment in the drying apparatus is opened upstream of the combustion air inlet in the pyrolysis gas combustion zone in the furnace The primary combustion air is supplied from the dry exhaust gas inlet and the primary combustion air is supplied from the primary air inlet at a low air ratio of about 0.7 to 0.8 to perform combustion treatment in a reducing atmosphere. By performing (Claims 1-4), the dry waste gas NH ₃ by it is possible to reduce the NOx generated in the combustion zone of the pyrolysis gas in, it is possible to reduce the NOx amount at the time of pyrolysis gas burning.
Further, in the reducing atmosphere, a suitable amount of dry exhaust gas having a temperature lower than that of the pyrolysis gas is blown into the cracking gas combustion furnace, and the temperature in the cracking gas combustion furnace is maintained at 1200 ° C. or less, whereby the cracking gas combustion furnace. This can protect the furnace wall and improve the durability of the cracked gas combustion furnace.

Further, by supplying secondary combustion air to the in-furnace gas after low NOx combustion in a reducing atmosphere in the pyrolysis gas combustion zone and performing a combustion treatment in an oxidizing atmosphere (claim 1), the reduction Unburned gas in the atmosphere can be completely burned.
Further, the remaining dry exhaust gas of the dry exhaust gas consumed in the combustion zone in the reducing atmosphere (preferably 70 to 90% of the dry exhaust gas: Claim 3) is secondarily introduced into the combustion gas in the oxidizing atmosphere. By performing the final combustion treatment (Claim 1), the NOx produced during combustion in the oxidizing atmosphere of the pyrolysis gas combustion zone is reduced and reduced by the self-denitration action by NH ₃ in a large amount of dry exhaust gas. While performing NOx combustion, deodorization and complete combustion can be performed by the dry exhaust gas and the secondary combustion air.

  Therefore, according to the present invention, the auxiliary fuel is used as needed to bring the total amount of the dry exhaust gas to about 950 ° C. in the final combustion treatment of the in-furnace gas without burning at a high temperature of about 1200 ° C. As a result, the combustion of pyrolysis gas after carbonization in the carbonization furnace in the cracked gas combustion furnace is completely accompanied by a reduction in the amount of NOx while keeping the fuel consumption rate low while minimizing the use of auxiliary fuel. This can be achieved by combustion.

Hereinafter, the present invention will be described in detail based on illustrated embodiments.
FIG. 1 is a system diagram of an apparatus for carbonizing a high water content organic substance according to an embodiment of the present invention, and FIG. 2 is a longitudinal sectional configuration diagram of a cracked gas combustion furnace.
In this embodiment, sewage sludge is treated as a highly water-containing organic substance, particularly a high water-containing nitrogen-containing organic substance.
As shown in FIG. 1, the carbonization processing apparatus according to the present embodiment is mainly dried by a dehydrator 10 for dewatering sewage sludge, a drying furnace 20 for directly drying hot water against the dewatered sewage sludge, and drying. A carbonization furnace 1 for carbonizing sewage sludge, a cracking gas combustion furnace 2 for mainly burning the pyrolysis gas generated in the carbonization furnace 1, and a high-temperature combustion gas from the cracking gas combustion furnace 2 is further combusted and heated. The carbonization furnace 1 is fed to the carbonization furnace 1 and the like.

  The drying furnace 20 is preferably a system in which hot air is brought into direct contact, but is not limited thereto, and may be any one that can be dried without burning dehydrated sludge. The carbonization furnace 1 is preferably an externally heated rotary kiln type. However, as long as it meets the purpose of the present invention, other forms of carbonization furnaces can be used.

The dehydrator 10 and the drying furnace 20 are connected by a line 110. The line 110 is preferably a pipe that can pump sludge by a pressure pump (not shown). The drying furnace 20 and the carbonization furnace 1 are connected by a line 21, and the line 21 is preferably a conveyor that can transport dried sludge.
The inside of the carbonization furnace 1 and the cracking gas combustion furnace 2 are connected by a line 19 that is a piping for the pyrolysis gas generated in the carbonization furnace 1, and carbide is separated from the pyrolysis gas in the line 19. A cyclone 32 to be removed is provided.
A line 34 and a line 33 for discharging the carbide 6 are respectively provided at the bottom of the cyclone 32 and the carbide outlet of the carbonization furnace 1.
Details of the cracked gas combustion furnace 2 will be described later.

The combustion exhaust gas line 41 connected to the outlet of the cracked gas combustion furnace 2 is connected to the combustion exhaust gas line 4 to the combustion apparatus 3 for the carbonization furnace, the combustion exhaust gas line 5 to the drying furnace 20, and the heat exchanger 7 described later. Combustion exhaust gas branched into three heating combustion exhaust gas lines and the combustion exhaust gas line 9 and heated to about 950 ° C. (usually 900 to 1000 ° C.) by combustion in the cracked gas combustion furnace 2 The fuel is sent to the combustion apparatus 3 for the carbonization furnace, the drying furnace 20, and the heat exchanger 7 through the combustion exhaust gas lines 4, 5, and 9.
In the carbonization furnace combustion apparatus 3, high-temperature combustion exhaust gas of about 950 ° C. (usually 900 to 1000 ° C.) from the cracked gas combustion furnace 2 is composed of fossil fuel such as LNG (natural gas) or heavy oil. It is heated to about 1100 ° C. (usually 1050 to 1150 ° C.) by combustion with auxiliary fuel and combustion air preheated by an air preheater 38 described later and supplied through the air line 61, and is supplied to the carbonization furnace 1. .

18 is a carbonization furnace exhaust gas line for discharging the carbonization furnace exhaust gas from the carbonization furnace 1, and is connected to an air preheater 38 for preheating combustion air to the cracked gas combustion furnace 2. The combustion air is preheated to about 380 ° C. (usually 360 to 400 ° C.), branched from the combustion air line 38a into three combustion air lines 39, 76, 77 described later, and sent to the cracked gas combustion furnace 2. It is like that. The three combustion air lines 39, 76, 77 are provided with flow control valves 39a, 76a, 77a for opening and closing the respective combustion air lines 39, 76, 77.
Reference numeral 13 denotes a fan for supplying combustion air to the air preheater 38. Reference numerals 80 and 82 denote auxiliary fuel supply lines for supplying auxiliary fuel into the cracked gas combustion furnace 2. This auxiliary fuel supply line is provided as necessary.
Further, the carbonization furnace exhaust gas after the combustion air is preheated by the air preheater 38 is sent to the exhaust gas treatment device 8 through the exhaust gas line 81 by the fan 14 and subjected to a necessary purification process, and then from the chimney 17 to the atmosphere. It is supposed to be discharged.

11 is a drying furnace exhaust gas for supplying the gas (hot air) after drying sludge in the drying furnace 20 to a temperature of about 200 ° C. (usually 180 to 220 ° C.) to the heat exchanger 7 for heating the gas. A line 12 is a circulation fan provided in the drying furnace exhaust gas line 11.
A high-temperature gas of about 950 ° C. (usually 900 to 1000 ° C.) is introduced into the heat exchanger 7 through a combustion exhaust gas line 9 branched from the combustion exhaust gas line 41 at the outlet of the cracked gas combustion furnace 2, and the drying furnace Three drying furnace exhaust gas lines branched from the drying furnace exhaust gas line 71 and the drying furnace exhaust gas line 71 by heating the drying furnace exhaust gas supplied from 20 through the drying furnace exhaust gas line 11 to about 530 ° C. (usually 510 to 550 ° C.). The gas is returned to the cracked gas combustion furnace 2 through 73, 74, and 75.
The distribution ratio of the drying furnace exhaust gas flow rate from the drying furnace exhaust gas line 71 at the outlet of the heat exchanger 7 to the three drying furnace exhaust gas lines 73, 74, 75 is distributed to the three drying furnace exhaust gas lines 73, 74, 75. This is done by the installed flow control valve.

15 is a heat exchanger for producing high-temperature air for preventing white smoke using the exhaust heat of the high-temperature exhaust gas obtained by heating the gas (the temperature-decreasing gas) that is recirculated to the combustion furnace 2 by the heat exchanger 7. The air supplied from the fan 16 is heated. The exhaust gas after being cooled by the heat exchanger 15 is combined with the exhaust gas that has passed through the air preheater 38 and supplied to the exhaust gas treatment device 8.

In FIG. 2 which shows the longitudinal cross-sectional block diagram of the said cracked gas combustion furnace 2, the pyrolysis gas inlet 201 connected to the said pyrolysis gas line 19 is provided in the uppermost part of this cracked gas combustion furnace 2, and the said carbonization furnace 1 is introduced into the furnace 2 d of the cracked gas combustion furnace 2 through the pyrolysis gas line 19.
A primary air inlet 202 connected to the combustion primary air line 39 branched from the combustion air line 38a is provided on the upper portion of the case 210 of the cracked gas combustion furnace 2, and the air preheater is provided. Primary air is supplied through a primary air line (combustion air line) 39 branched from the combustion air line 38a at the 38 outlet.

Further, on the side portion of the cylindrical case 210 of the cracked gas combustion furnace 2, the dry exhaust gas upper inlet 203 and the two secondary airs flow downward from the pyrolysis gas inlet 201 in the flow direction of the pyrolysis gas. Inlet ports (may be three or more) 204 and 205, two dry exhaust gas lower inlet ports (may be one or more than three) 206 and 207, and combustion exhaust gas outlet 208 are provided.
The drying furnace exhaust gas heated to about 530 ° C. (usually 510 to 550 ° C.) by the heat exchanger 7 branches from the drying furnace exhaust gas line 71 and the drying furnace exhaust gas line 71 to the dry exhaust gas upper inlet 203. Is supplied through the dried furnace exhaust gas line 73. Further, the drying furnace exhaust gas is supplied to the two dry exhaust gas lower inlets 206 and 207 through the drying furnace exhaust gas lines 74 and 75 branched from the drying furnace exhaust gas line 71, respectively.
Further, secondary air is supplied to the two secondary air inlets 204 and 205 through secondary air lines (combustion air lines) 76 and 77 branched from the combustion air line 38a at the outlet of the air preheater 38, respectively. It comes to be supplied.

The combustion exhaust gas outlet 208 is connected to the combustion exhaust gas line 41, and the combustion exhaust gas heated to about 950 ° C. (usually 900 to 1000 ° C.) by combustion in the cracked gas combustion furnace 2 is combusted. It is sent into the exhaust gas line 41.
Further, in the case 210 of the cracked gas combustion furnace 2, the auxiliary fuel lines 80 and 82 are connected in the vicinity of the drying furnace exhaust gas line 73 and in the vicinity of the two dry exhaust gas lower inlets 206 and 207. A fuel inlet (not shown) is installed as necessary, and auxiliary fuel that has passed through auxiliary fuel lines 80 and 82 can be introduced into the upper or lower combustion zone of the cracked gas combustion furnace 2.

Next, a method for carbonizing sludge and a method for treating pyrolysis gas using the high water content organic carbonization apparatus according to this embodiment will be described.
First, sewage sludge is introduced into the dehydrator 10 and dehydrated until the water content of the sewage sludge is about 80%. Next, the dewatered sewage sludge is sent to the drying furnace 20. In the drying furnace 20, the sludge is dried until the water content is about 30%.
Drying in the drying furnace 20 is performed by bringing the flue gas introduced through the line 5 branched from the line 41 from the cracked gas combustion furnace 2 into direct contact with sludge. In this case, since the temperature of the combustion exhaust gas from the cracked gas combustion furnace 2 is as high as about 950 ° C. (usually 900 to 1000 ° C.) as described above, the combustion exhaust gas is connected to the combustion exhaust gas inlet / outlet of the drying furnace 20. While circulating the circulation line 50 connected to the line 5 with the fan 12, the temperature is lowered to about 830 ° C. (usually 810 to 850 ° C.) by exchanging heat with the low-temperature sewage sludge in the drying furnace 20. It acts on the drying furnace 20.

Here, the temperature of the combustion exhaust gas from the cracked gas combustion furnace 2 needs to be maintained at a high temperature of about 950 ° C. (usually 900 to 1000 ° C.) in order to act on the combustion apparatus 3 for carbonization furnace. If the combustion exhaust gas is directly applied to the drying furnace 20, the durability of the drying furnace 20 decreases, and therefore the combustion exhaust gas is connected to the circulation line 50 connecting the combustion exhaust gas inlet / outlet of the drying furnace 20 and the line 5 with the fan. 12, the temperature is lowered to about 830 ° C. (usually 810 to 850 ° C.) while being circulated by 12, and is allowed to act on the drying furnace 20.
The sewage sludge dried in the drying furnace 20 is introduced into the carbonization furnace 1 through the line 21.
In the carbonization furnace 1, sewage sludge is heated to about 300 to 600 ° C. in an oxygen-deficient atmosphere to perform carbonization to generate pyrolysis gas and carbide 6 that is a solid fuel. The carbide 6 is discharged through the line 33.
The heating in the carbonization furnace 1 is performed by supplying the combustion exhaust gas heated to about 1100 ° C. (usually 1050 to 1150 ° C.) to the outer cylinder of the carbonization furnace 1 by the combustion apparatus 3 for the carbonization furnace. It is performed by indirect heating without direct contact with sewage sludge.

The carbonization furnace exhaust gas that has been subjected to carbonization treatment of sewage sludge in the carbonization furnace 1 and cooled to about 700 ° C. (usually 680 to 720 ° C.) is introduced into the air preheater 38 through the line 18. In the air preheater 38, the combustion air supplied by the fan 13 is preheated to about 380 ° C. (usually 360 to 400 ° C.) by the carbonization furnace exhaust gas and sent to the cracked gas combustion furnace 2.
In this case, the combustion air from the air preheater 38 is branched from the combustion air line 38a at the outlet of the air preheater 38 to the three combustion air lines 39, 76, 77, and the cracked gas combustion furnace 2 The primary air inlet 202 and the two secondary air inlets 204 and 205 are introduced into the primary air inlet 202 and the two secondary air inlets 204 and 205. The amount is determined by changing the opening degree of the flow control valves 39a, 76a, 77a provided in the combustion air lines 39, 76, 77, respectively.
The carbonization furnace exhaust gas cooled to about 300 ° C. (usually 280 to 320 ° C.) by the preheating of the combustion air in the air preheater 38 was sent to the exhaust gas treatment device 8 by the fan 14 and required purification treatment was performed. Then, it is discharged from the chimney 17 into the atmosphere.
On the other hand, the pyrolysis gas generated in the carbonization furnace 1 is sent to the cyclone 32 through the line 19, and the carbide 6 is separated and removed by the cyclone 32 and then introduced into the cracking gas combustion furnace 2. The carbide 36 separated in the cyclone 32 is discharged through a line 34.

Next, based on FIG. 2, the operation | movement of the cracked gas combustion furnace 2 which is the summary of this invention is demonstrated.
The pyrolysis gas from the carbonization furnace 1 introduced into the furnace 2d from the pyrolysis gas inlet 201 provided at the uppermost part of the cracking gas combustion furnace 2 flows in the furnace 2d downward. Further, primary air (combustion air) preheated by the air preheater 38 is introduced from the primary air inlet 202 on the upper side of the cracked gas combustion furnace 2.
Further, a region Z1 from the pyrolysis gas inlet 201 through the dry exhaust gas upper inlet 203 to the upper secondary air inlet 204 is a reduction zone, and is supplied from the primary air inlet 202 to the reduction zone Z1. The primary air is supplied under the condition that the air ratio is 0.7 to 0.8 and the residence time is 1.5 seconds or more. In addition, the dryer exhaust gas having an air ratio of about 0.1 (usually 0.05 to 0.15) that is introduced into the reduction zone Z1 from the dry exhaust gas upper inlet 203 is subjected to the drying treatment in the dryer 20. It is blown into the reduction zone Z1 at a flow rate of 10 to 30% of the exhaust gas from the dryer at a blowing flow rate of about 30 m / s (usually 15 to 45 m / s).

Therefore, in the reduction zone Z1, combustion treatment in a reducing atmosphere is performed by supplying primary air having a low air ratio of 0.7 to 0.8 into the pyrolysis gas and supplying exhaust gas from the dryer. By doing so, it becomes possible to reduce NOx generated in the combustion zone of the pyrolysis gas by NH ₃ in the exhaust gas of the dryer, and the amount of NOx at the time of pyrolysis gas combustion can be reduced.
In addition, a suitable amount of dryer exhaust gas having a temperature lower than that of the pyrolysis gas is blown into the reduction zone Z1 into the decomposition gas combustion furnace 2 to maintain the temperature in the decomposition gas combustion furnace 2 at 1200 ° C. or less, thereby The furnace wall of the gas combustion furnace can be protected, and the durability of the cracked gas combustion furnace 2 can be improved.

Next, in the oxidation zone Z2, secondary air (air ratio λ = 0.25 to 0.35) is supplied from the secondary air inlet 204 to the pyrolysis gas after the combustion treatment in the reducing atmosphere in the reduction zone Z1. The amount of input oxygen λ = 1.05 to 1.15) is supplied, and the unburned portion in the reduction zone Z1 is burned at about 1200 ° C. (usually 1150 to 1250 ° C.).
In this way, by supplying secondary air in the oxidation zone Z2 to the in-furnace gas (pyrolysis gas) after low NOx combustion in the reduction atmosphere in the reduction zone Z1, combustion processing in the oxidation atmosphere is performed. The unburned gas in the reducing atmosphere can be completely burned.

Next, in the exhaust gas combustion zone Y of the dryer, the air ratio from the secondary air inlet 205 to the in-furnace gas (pyrolysis gas) after the combustion treatment in the oxidation zone Z2 is about 0.35 (usually 0). .3 to 0.4) secondary air is blown in and introduced at a flow rate of about 30 m / s (usually 25 to 35 m / s) to ensure the oxygen concentration (3 to 4% or more) necessary for self-denitration by dryer exhaust gas. To do.
Thereafter, from the dried exhaust gas lower inlets 206 and 207, the dryer exhaust gas flows at a flow rate of 70 to 90% of the dryer exhaust gas after the drying treatment in the dryer 20, and a flow rate of about 30 m / s (usually 25 to 25 m / s). 35 m / s) and blown into the dryer exhaust gas combustion zone Y. The combustion temperature here is preferably 950 ° C. or more, and the residence time is preferably 2 seconds or more.
By the above processing, the temperature of the combustion exhaust gas at the outlet of the combustion exhaust gas outlet 208 is maintained at about 950 ° C. (usually 900 to 1000 ° C.).
When the temperature of the combustion exhaust gas cannot be maintained at about 950 ° C. (usually 900 to 1000 ° C.), the auxiliary fuel passing through the auxiliary fuel lines 80 and 82 is supplied to the pyrolysis gas combustion zone Z or the dryer exhaust gas combustion zone Y. By introducing it, deodorization and complete combustion can be performed.

Accordingly, in the exhaust gas combustion zone Y of the dryer, the remaining exhaust gas of the dry exhaust gas (dry exhaust gas of the dry exhaust gas consumed by the combustion in the reduction zone Z1 is converted into the combustion gas from the oxidation zone Z2 of the pyrolysis gas combustion zone Z. 70 to 90%) is added secondarily and the final combustion treatment is performed, so that self-denitration by NH ₃ in a large amount of dry exhaust gas is generated during combustion in the oxidizing atmosphere of the pyrolysis gas combustion zone Z The reduced NOx can be reduced to achieve low NOx combustion.

  Therefore, according to the above-described embodiment of the present invention, the auxiliary fuel is used only when necessary in the final combustion treatment of the in-furnace gas using the dry exhaust gas and the secondary combustion air. The combustion of the pyrolysis gas after the carbonization treatment in the carbonization furnace 1 in the cracked gas combustion furnace 2 can be achieved with a reduction in the amount of NOx while keeping the fuel consumption rate low.

  Returning to FIG. 1, the combustion exhaust gas at about 950 ° C. (usually 900 to 1000 ° C.) generated in the cracked gas combustion furnace 2 is supplied from the combustion exhaust gas line 41 at the outlet of the cracked gas combustion furnace 2 into three combustion exhaust gases for heating. Branches to lines 4, 5 and 9, and is sent to the combustion apparatus for carbonization furnace 3, the drying furnace 20 and the heat exchanger 7 through the combustion exhaust gas lines 4, 5 and 9, respectively.

A cracked gas combustion furnace was prototyped, and a comparison was made between when dry exhaust gas was introduced and when dry exhaust gas was not introduced. When the combustion temperature was about 900 ° C., the NO _x concentration at the outlet was 225 ppm when no dry exhaust gas was introduced, but when dry exhaust gas was introduced, it was reduced to 87 ppm and the NO conversion rate was 13. Reduced from 2% to 7.2%. The NO _x concentration is a 12% conversion value.

It is a systematic diagram explaining the carbonization processing apparatus of the high water content organic substance which concerns on embodiment of this invention. It is a longitudinal cross-sectional block diagram explaining position embodiment of the cracked gas combustion furnace employ | adopted by embodiment of FIG. It is a systematic diagram corresponding to FIG. 1 explaining the conventional carbonization processing apparatus of a high water content organic substance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Carbonization furnace 2 Cracking gas combustion furnace 2d Furnace 201 Pyrolysis gas inlet 202 Primary air inlet 203 Dry exhaust gas upper inlet 204 Secondary air inlet 205 Secondary air inlet 206 Dry exhaust lower inlet 207 Dry exhaust lower part introduction Port 208 Combustion exhaust gas outlet 210 Case 3 Combustion device for carbonization furnace 6 Carbide 7 Heat exchanger 10 Dehydrator 20 Drying furnace 38 Air preheater

Claims (6)

  High moisture content organic matter carbonization treatment which dries the high moisture content organic matter with a drying device, carbonizes the moisture content organic matter after passing through the drying treatment in a carbonization furnace, and burns the pyrolysis gas generated by the carbonization treatment A pyrolysis gas treatment method for a system, wherein pyrolysis gas generated in the carbonization furnace is introduced into a cracking gas combustion furnace, and a part of the dry exhaust gas after the drying treatment in the drying apparatus in the cracking gas combustion furnace Is supplied to the combustion gas in the reducing atmosphere by supplying the primary combustion air, and then the secondary combustion air is supplied to the combustion gas in the reducing atmosphere to perform the combustion processing in the oxidizing atmosphere. Next, the dry exhaust gas is secondarily introduced into the combustion gas in the oxidizing atmosphere and the final combustion treatment is performed. A pyrolytic gas treatment method for a high water content organic matter carbonization treatment system.   2. The pyrolysis gas treatment method for a highly hydrous organic carbonization treatment system according to claim 1, wherein the dry exhaust gas is introduced into the combustion gas in a plurality of stages in the final combustion treatment and both are combusted at a high temperature.   10 to 30% of the dry exhaust gas input to the cracked gas combustion furnace is the primary input gas amount, and 70 to 90% of the dry exhaust gas is the secondary input gas amount. The pyrolysis gas processing method of the high water content organic substance carbonization processing system of Claim 1.   As the primary combustion air and the secondary combustion air, air preheated by carbonization exhaust gas discharged after carbonization in the carbonization furnace by an air preheater is used, and the primary combustion air and the primary combustion air are mixed with the primary combustion air by an air amount adjusting means. 2. The pyrolysis gas treatment method for a high water content organic carbonization system according to claim 1, wherein the ratio of the supply air amount to the secondary combustion air is adjusted and supplied to the cracking gas combustion furnace.   High moisture content organic matter carbonization treatment which dries the high moisture content organic matter with a drying device, carbonizes the moisture content organic matter after passing through the drying treatment in a carbonization furnace, and burns the pyrolysis gas generated by the carbonization treatment In the pyrolysis gas treatment device of the system, a pyrolysis gas inlet for introducing the pyrolysis gas generated in the carbonization furnace, and a multistage dry exhaust gas into which the dry exhaust gas after the drying treatment in the drying device is introduced A cracked gas combustion furnace having an inlet, a plurality of stages of combustion air inlets for introducing combustion air, and a combustion exhaust gas outlet for sending combustion exhaust gas; A gas inlet is provided on the most upstream side so that the pyrolysis gas can flow in the longitudinal direction from the pyrolysis gas inlet to the combustion exhaust gas outlet, and one of the plurality of stages of the dried exhaust gas inlet is Combustion air introduction It is possible to perform combustion treatment in the reducing atmosphere of the pyrolysis gas by opening the upstream side of the other, and opening the other dry exhaust gas inlet to the downstream side of the combustion air inlet, A pyrolysis gas treatment apparatus for a high water content organic carbonization treatment system, characterized in that combustion gas in the furnace can be combusted with the combustion air and the dry exhaust gas.   The cracked gas combustion furnace has a plurality of stages of primary air inlets of the pyrolyzed gas inlet and the plurality of stages of combustion air inlets on the most upstream side along the flow direction of the pyrolyzed gas. One of the dry exhaust gas inlets, the secondary air inlet of the plurality of stages of combustion air inlets, the other of the multiple stages of the dry exhaust gas inlets, and the combustion exhaust gas outlet along the longitudinal direction. The pyrolysis gas treatment apparatus for a high water content organic matter carbonization processing system according to claim 5, wherein the pyrolysis gas treatment device is constituted by a cylindrical body disposed.

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