JP7240254B2 - Method for treating woody tar-containing wastewater generated at a woody biomass power generation facility - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for treating woody tar-containing wastewater generated as a by-product when purifying combustible pyrolysis gas generated by pyrolyzing woody biomass in a woody biomass power generation facility.

As an effective use of resources, woody biomass such as waste wood and thinned wood is thermally decomposed in a gasification furnace in an oxygen-free or low-oxygen environment to generate combustible pyrolysis gas containing hydrogen and methane. Also known is woody biomass power generation in which the combustible pyrolysis gas is purified and then combusted in a gas engine or the like for use in power generation.

In addition, since a large amount of tar-containing wastewater is generated as a by-product during the purification process of pyrolysis gas, the collected tar-containing wastewater has conventionally been disposed of as industrial waste or put into a combustion treatment furnace heated and maintained at a high temperature. are incinerated (see Patent Document 1).

In addition, as an example of utilizing woody tar as a valuable resource instead of simply disposing of it as industrial waste or incinerating it, the present applicant has made it possible to burn the tar as burner fuel by preheating it, and We have proposed a burner device that can be used for heating and drying such as a dryer (see Patent Document 2).

JP 2008-25876 A JP 2010-91198 A

However, at present, there are few cases where woody tar is effectively used as burner fuel in place of fossil fuels such as heavy oil and propane gas, and a large amount of tar is left over. Therefore, although there is no choice but to dispose of it as described above or to bring it into a combustion treatment furnace and incinerate it, it costs a lot of money to dispose of it as industrial waste, and a large amount of waste is also incinerated in a combustion treatment furnace. Since fossil fuels are required and costs accordingly, it is desirable to have a treatment method that can efficiently treat the amount of fossil fuels used as much as possible.

In view of the above points, an object of the present invention is to provide a treatment method capable of efficiently treating woody tar-containing wastewater generated at a woody biomass power generation facility.

In order to solve the above problems, the present inventors focused on a burner device using woody tar as fuel, which was previously proposed by the present applicant. We thought that the tar component contained in the tar-containing wastewater generated at the power plant could be effectively used as burner fuel for the combustion treatment furnace, and that the tar-containing wastewater could be treated efficiently while reducing the amount of fossil fuels used. The inventors have arrived at the present invention.

That is, in the method for treating woody tar-containing wastewater generated in a woody biomass power generation facility according to claim 1 of the present invention, there is provided a wastewater storage step of storing tar-containing wastewater in a tank, and a specific gravity of the stored tar-containing wastewater. A specific gravity separation step of separating heavy tar and water-containing light tar according to the difference, a tar storage step of storing the separated heavy tar and water-containing light tar in separate tanks, and heating the water-containing light tar. A heat separation step of evaporating water to separate light tar and water vapor containing tar volatile components, and a combustion treatment furnace equipped with a burner for burning the heavy tar, wherein the light tar and water vapor are placed in a furnace body. and a combustion air preheating step of preheating the combustion air supplied to the burner to a predetermined temperature. While supplying preheated combustion air to the burner of the combustion treatment furnace, the heavy tar is burned as fuel for the burner, and the light tar separated from the water-containing light tar and steam are introduced into the furnace body. It is characterized by combustion treatment.

Further, in the method for treating woody tar-containing wastewater generated in a woody biomass power generation facility according to claim 2 of the present invention, during preheating operation of the combustion treatment furnace, is blown into the furnace body of the combustion treatment furnace and burned as an auxiliary fuel.

Further, in the method for treating woody tar-containing wastewater generated in a woody biomass power generation facility according to claim 3 of the present invention, the combustion air of the burner is heat-exchanged with the exhaust gas discharged from the combustion treatment furnace. It is characterized by preheating.

Further, in the method for treating woody tar-containing wastewater generated in a woody biomass power generation facility according to claim 4 of the present invention, steam separated by heating from water-containing light tar is separated from the tangential direction of the furnace body of the combustion treatment furnace. It is characterized by introducing

According to the method for treating woody tar-containing wastewater generated in a woody biomass power generation facility according to claim 1 of the present invention, the wastewater storage step of storing the tar-containing wastewater in a tank and the specific gravity of the stored tar-containing wastewater A specific gravity separation step of separating heavy tar and water-containing light tar according to the difference, a tar storage step of storing the separated heavy tar and water-containing light tar in separate tanks, and heating the water-containing light tar. A heat separation step of evaporating water to separate light tar and water vapor containing tar volatile components, and a combustion treatment furnace equipped with a burner for burning the heavy tar, wherein the light tar and water vapor are placed in a furnace body. and a combustion air preheating step of preheating the combustion air supplied to the burner to a predetermined temperature. While supplying preheated combustion air to the burner of the combustion treatment furnace, the heavy tar is burned as fuel for the burner, and the light tar separated from the water-containing light tar and steam are introduced into the furnace body. Therefore, the combustible heavy tar separated and recovered from the tar-containing wastewater can be effectively used as a fuel for the burner of the combustion treatment furnace, while the remaining flame-retardant water-containing light tar is also used for the combustion treatment furnace. Combustion treatment can be performed by introducing it into the furnace body, and tar-containing wastewater generated at a woody biomass power generation facility can be efficiently treated without using fossil fuels such as heavy oil as much as possible.

Further, according to the method for treating woody tar-containing wastewater generated in a woody biomass power generation facility according to claim 2 of the present invention, during preheating operation of the combustion treatment furnace, the wastewater generated in the woody biomass power generation facility Since the pyrolysis gas for power generation is blown into the furnace main body of the combustion treatment furnace and burned as auxiliary fuel, the amount of fossil fuel used during the preheating operation of the combustion treatment furnace can be reduced, and the preheating operation can be completed early. can effectively treat tar-containing wastewater. In addition, the pyrolysis gas used as supplementary fuel is diverted from the gas generated for power generation at a nearby woody biomass power generation facility, so it can be supplied relatively easily and cheaply, and the effect of reducing the environmental load can be expected. .

Further, according to the method for treating woody tar-containing wastewater generated in a woody biomass power generation facility according to claim 3 of the present invention, the combustion air of the burner exchanges heat with the exhaust gas discharged from the combustion treatment furnace. Since the exhaust gas generated in the combustion treatment furnace is heated and preheated, the thermal energy possessed by the exhaust gas generated in the combustion treatment furnace can be effectively used without waste, and further reduction of the environmental load can be expected.

Further, according to the method for treating woody tar-containing wastewater generated in a woody biomass power generation facility according to claim 4 of the present invention, steam separated by heating from water-containing light tar is separated from the tangential line of the furnace body of the combustion treatment furnace. Since the steam is introduced from the direction, the steam can be brought into intimate contact with the combustion gas from the burner while swirling along the inner wall of the furnace body, and the tar volatile components contained in the steam can be efficiently burned.

1 is a flowchart of a method for treating woody tar-containing wastewater generated in a woody biomass power generation facility according to the present invention. FIG. FIG. 4 is a schematic explanatory diagram showing one embodiment of the same; FIG. 3 is a partially cutaway detailed view of the combustion treatment furnace of FIG. 2; FIG. 4 is a cross-sectional view taken along the line AA with a part of FIG. 3 omitted;

In the method for treating woody tar-containing wastewater according to the present invention, a wastewater storage step of temporarily storing woody tar-containing wastewater generated in a woody biomass power generation facility in a tank; is separated into a combustible heavy tar with a relatively large specific gravity and a flame-retardant water-containing light tar with a relatively small specific gravity and a large amount of water in an appropriate specific gravity separator, and the specific gravity separation is performed. and a tar storage step of storing the heavy tar and the water-containing light tar in separate tanks.

In addition, a heating separation step of heating the stored water-containing light tar to evaporate the contained water to separate it into light tar and steam containing a small amount of tar volatile components, and a combustion treatment furnace equipped with a burner for burning the heavy tar. A tar combustion treatment step in which the water vapor and the light tar are separately introduced into the furnace body and burned, and the combustion air (outside air) supplied to the burner is accelerated to atomize the heavy tar to the burner. and a combustion air preheating step for preheating the air to a predetermined temperature at which it can be combusted as fuel, for example, a high temperature of about 200 to 300°C.

In addition, the high-viscosity heavy tar separated from the tar-containing wastewater is heated and preheated to a predetermined temperature, for example, about 70 to 90° C., which can be smoothly supplied as a burner fuel and can be adjusted to a viscosity that is easily atomized. While supplying the combustion air (preheated air) to the burner of the combustion treatment furnace, the heavy tar is burned as fuel for the burner, and the light tar separated from the water-containing light tar and water vapor are separated from the water-containing light tar into the furnace body in a high-temperature atmosphere. It is introduced separately into the inside and is combusted.

As the combustion treatment furnace, for example, it is equipped with a substantially cylindrical furnace body in which casters having heat storage properties are provided around the inner wall surface, and a two-fluid system that injects heavy tar together with compressed air at the base end of the furnace body. A burner equipped with an injection nozzle and a preheating burner that uses fossil fuels such as heavy oil and propane gas are installed side by side.

Heavy tar is more viscous and flame-retardant than fossil fuels such as heavy oil at room temperature, so it is difficult to use it as burner fuel as it is, but the heavy tar is heated and maintained at about 70-90°C. After reducing the viscosity, a two-fluid injection nozzle is adopted to inject it with compressed air to atomize it, and the combustion air is preheated to a high temperature of about 200 to 300 ° C by an appropriate heating means. By doing so, atomization of heavy tar is promoted, and flame-retardant heavy tar can be stably burned as burner fuel.

Further, preferably, the combustion treatment furnace is installed in the vicinity of the woody biomass power generation facility, and a part of the pyrolysis gas generated for power generation in the woody biomass power generation facility is burned during the preheating operation of the combustion treatment furnace. It may be blown into the furnace body of the treatment furnace and burned as an auxiliary fuel, thereby reducing the amount of fossil fuel used during preheating operation, and preheating operation can be completed early to efficiently dispose of tar-containing wastewater. can be processed.

Further, preferably, when preheating the combustion air (outside air) for the burner, the heat may be exchanged with the exhaust gas discharged from the combustion treatment furnace to preheat the air. The thermal energy possessed by the high-temperature exhaust gas can be used effectively without waste.

Furthermore, preferably, the steam separated by heating from the water-containing light tar may be introduced from the tangential direction of the furnace main body of the combustion treatment furnace. can be brought into close contact with the combustion gas, and the tar volatile components contained in the steam can be efficiently burned.

In treating woody tar-containing wastewater generated in a woody biomass power generation facility, the generated tar-containing wastewater is put into a wastewater storage tank as needed and stored. The tar-containing wastewater consists of heavy tar that is relatively combustible and can be used as burner fuel, and water-containing light tar that contains a large amount of water and is relatively incombustible and is unsuitable as burner fuel. The heavy tar has a specific gravity. On the other hand, water-containing light tar is characterized by a small specific gravity.

Utilizing the characteristics (difference in specific gravity), the tar-containing wastewater stored in the wastewater storage tank is separated into heavy tar and water-containing light tar by an appropriate specific gravity separator such as a gravity sedimentation type or a centrifugal separation type. , the heavy tar and the water-containing light tar separated by specific gravity are stored in individual storage tanks. Next, the water-containing light tar that has been separated by specific gravity is heated to evaporate the contained water, and is further separated into light tar and water vapor containing tar volatile components.

Then, the preheating burner of the combustion treatment furnace is ignited to burn fossil fuels such as heavy oil and propane gas, and if necessary, a part of the pyrolysis gas generated for power generation at the nearby woody biomass power generation facility is burned. The fuel is blown into the furnace body of the treatment furnace and burned as auxiliary fuel to preheat the furnace body of the combustion treatment furnace.

At this time, since the burner uses heavy tar, which is highly viscous and flame-retardant compared to fossil fuels such as heavy oil, the heavy tar is heated to reduce its viscosity and then injected together with compressed air. The heavy tar is atomized and stably burned by preheating the combustion air while atomizing the tar.

When the temperature in the furnace body reaches approximately 850° C., at which the volatile components of tar and light tar can be completely combusted, steam containing some volatile components of tar separated from the water-containing light tar by heating and light tar are added to the furnace body. It is introduced separately into the inside and burned.

In this way, tar-containing wastewater generated at a woody biomass power generation facility is separated into combustible heavy tar and flame-retardant water-containing light tar using the difference in specific gravity, and the heavy tar is heated to raise its temperature. In addition to atomization, the combustion air is also preheated to promote atomization, making it possible to effectively use it as fuel for burners in combustion treatment furnaces. The light tar is heated and further heated and separated into steam containing tar volatile components and light tar, and then introduced individually into the furnace body of a combustion treatment furnace under a high-temperature atmosphere to which the combustion gas from the burner is supplied. By doing so, efficient combustion treatment can be performed, and a large amount of tar-containing wastewater can be suitably treated while reducing the amount of fossil fuels such as heavy oil used.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a flowchart showing a method for treating woody tar-containing wastewater generated as a by-product at a woody biomass power generation facility. Process 2, gas refining process 3, power generation process 4, wastewater storage process 5 in which tar-containing wastewater generated in gas refining process 3 is combusted, specific gravity separation process 6, tar storage process 7 (hydrous light tar storage process 8. It consists of a heavy tar storage process 9), a heat separation process 10, a tar combustion treatment process 11, and a combustion air preheating process 12.

In the gasification step 2, woody biomass such as waste wood and thinned wood is pyrolyzed in an oxygen-free or low-oxygen gasification furnace of a woody biomass power generation facility to generate combustible pyrolysis gas. . In the gas refining step 3, the generated combustible pyrolysis gas is refined by removing tar components that adversely affect combustion in a gas engine by means of a gas purifier. In the power generation step 4, the refined pyrolysis gas is supplied to a gas engine, which is a power generator, and burned to generate power.

In the wastewater storage step 5, tar-containing wastewater generated as a by-product in the gas refining step 3 is stored in a wastewater storage tank as needed. In the specific gravity separation step 6, the tar-containing wastewater stored in the wastewater storage tank is removed at an appropriate timing (for example, when the wastewater storage tank is almost full). A suitable gravity separator is used to separate the water-containing light tar, which is relatively combustible, and the heavy tar, which has a relatively high specific gravity. In the water-containing light tar storage step 8 of the tar storage step 7, the water-containing light tar separated by specific gravity from the tar-containing wastewater is stored in a water-containing light tar storage tank. Gravity-separated heavy tar is stored in a heavy tar storage tank.

In the heat separation step 10, the flame-retardant water-containing light tar stored in the water-containing light tar storage tank is heated to about 70 to 90° C. by a water-containing light tar heating means such as a heater to evaporate the contained water. It is further separated into water vapor containing a small amount of tar volatile components and light tar. Further, in the tar combustion treatment step 11, the light tar and steam are separately introduced into a furnace main body of a combustion treatment furnace equipped with a burner for burning the heavy tar, and are burned. Further, in the combustion air preheating step 12, the combustion air (outside air) supplied to the burner of the combustion treatment furnace is heat-exchanged with the high-temperature exhaust gas discharged from the combustion treatment furnace by a heat exchanger to obtain approximately 200 Preheat to ~300°C.

Then, the heavy tar stored in the heavy tar storage tank in the heavy tar storage step 9 is heated by a heavy tar heating means such as a heater so that it can be smoothly supplied as a burner fuel and has a viscosity that is easily atomized. After heating to about 70 to 90 ° C., which can be adjusted, the combustion air (preheated air) preheated to about 200 to 300 ° C. is supplied to the burner of the combustion treatment furnace, and heavy tar is supplied to the burner. While burning as a fuel, the light tar and water vapor separated by heating from the water-containing light tar in the heat separation step 10 are individually introduced into the furnace main body of the combustion treatment furnace under a high-temperature atmosphere and burned. I have to.

FIG. 2 is a schematic explanatory diagram showing an embodiment of a woody biomass power generation facility, a combustion treatment furnace used in the tar combustion treatment step 11, ancillary equipment, and the like. In FIG. 2, reference numeral 13 denotes a woody biomass power generation facility. In the woody biomass power generation facility 13, woody biomass such as waste wood and thinned wood is thermally decomposed under oxygen-free or low-oxygen conditions to produce combustible heat. A gasification furnace 14 that generates a cracked gas, a gas purifier 15 that cools the pyrolysis gas generated in the gasification furnace 14, condenses and removes tar components as impurities, and performs purification treatment, and pyrolysis that has undergone purification treatment. It is equipped with a pyrolysis gas storage tank 16 for storing gas, a gas engine 17 for supplying and burning the stored pyrolysis gas in predetermined amounts, and generating power. Reference numeral 18 denotes a pyrolysis gas supply pipe for supplying the pyrolysis gas from the pyrolysis gas storage tank 16 to the gas engine 17 .

In the vicinity of the woody biomass power generation facility 13, a wastewater storage tank 19 for storing wastewater containing tar components (tar-containing wastewater) removed from the pyrolysis gas by the gas purifier 15 is provided. The difference in specific gravity between combustible heavy tar that can use tar-containing wastewater stored in the storage tank 19 as burner fuel and flame-retardant water-containing light tar that is high in water content and unsuitable as burner fuel is utilized. It is equipped with a specific gravity separator 20 such as a gravity sedimentation type or a centrifugal type, for example.

In the vicinity of the woody biomass power generation facility 13, together with the wastewater storage tank 19 and the gravity separator 20, a heavy tar for storing heavy tar separated and recovered from the tar-containing wastewater by the gravity separator 20 is stored. A storage tank 21, a water-containing light tar storage tank 22 for storing water-containing light tar, and a combustion treatment furnace 23 for burning the heavy tar and the water-containing light tar stored in the storage tanks 21 and 22 are installed side by side. .

The combustion treatment furnace 23, as shown in FIGS. A burner 28 equipped with a two-fluid type injection nozzle 27 that injects heavy tar while atomizing it together with compressed air supplied from a compressor 26 on the base end side, and a preheating burner 29 that uses propane gas, which is a fossil fuel. It has

Further, on the base end side of the furnace body 25 where the flames of the burner 28 and the preheating burner 29 are formed and the temperature is particularly high, steam containing tar volatile components separated from the water-containing light tar by heating is supplied to the furnace body 25. The steam introduced into the furnace body 25 by connecting the steam introduction pipe 30 introduced from the tangential direction is, as indicated by the arrow in FIG. It is configured to flow down in the downstream direction while turning along. As a result, the steam can be brought into intimate contact with the combustion gas from the burner 28 at a high temperature, and the volatile components of tar, which are difficult to burn due to the small amount contained in the steam, can be efficiently burned. .

In this embodiment, as shown in FIG. 4, two steam introduction pipes 30 are connected, but the number is not limited to this, and for example, only one is possible. However, as in the present embodiment, by connecting a plurality of the furnace body 25 with the connection positions slightly shifted along the circumference direction, as shown by the arrows in FIG. It is possible to agitate the water vapor at the time of merging, and an improvement in the combustion efficiency of the contained tar volatile components can be expected.

In addition, the light tar separated by heat from the water-containing light tar is injected into the intermediate portion of the furnace body 25 on the downstream side of the connection position of the steam introduction pipe 30 while being atomized together with the compressed air supplied from the compressor 31. A light tar introduction pipe 33 equipped with a fluid type injection nozzle 32 is connected, and fine particles of light tar injected and introduced from the light tar introduction pipe 33 are atomized in the furnace main body 25 under high temperature, and the state thereof. By coming into contact with the combustion gas from the burner 28, efficient combustion treatment is possible.

The furnace length of the furnace main body 25 is such that the tar volatile components and light tar contained in the steam can be completely burned in a high temperature atmosphere of about 850° C. It is preferable to set the furnace length so that it takes about 2 seconds or more for the steam introduced from 30 and the light tar fine particles introduced from the light tar introduction pipe 33 in the middle of the furnace body 25 to pass through the furnace body 25 .

A reduced diameter portion (throttled portion) 34 is formed on the inner wall surface of the terminal portion of the furnace body 25 further downstream from the connection position of the light tar introduction pipe 33, and is indicated by the arrow in FIG. As shown, part of the mixture of steam and light tar that flows downstream while swirling along the surface of the heat storage casters 24 that are the inner walls of the furnace body 25 collides with the diameter-reduced portion 34 and moves upstream. By being pushed back into the furnace body 25, an irregular turbulent flow is generated in the furnace body 25, which increases the chance of contact with the combustion gas from the burner 28, and improves the combustion efficiency of tar volatile components and light tar contained in the steam. We are working to improve

35 in the figure is an exhaust duct for leading out the exhaust gas from the furnace main body 25 of the combustion treatment furnace 23. In the middle of the exhaust duct 35, an exhaust gas temperature sensor 36 for detecting the temperature of the exhaust gas and a heat exchanger 37 are installed. I have. Reference numeral 38 in the figure denotes a preheated air supply duct for supplying preheated combustion air to the burner 28. The preheated air supply duct 38 is equipped with a blower 39 at its base end. is connected to the heat exchanger 37 in the middle, and the normal temperature combustion air (outside air) supplied from the blower 39 is heated by the heat exchanger 37 with the high temperature exhaust gas discharged from the furnace main body 25. It is configured to be replaced and preheated.

In this embodiment, the combustion air supplied to the burner 28 is preheated by heat exchange with the exhaust gas discharged from the furnace main body 25 of the combustion treatment furnace 23, but the present invention is limited to this. For example, it may be preheated by a heater or the like, or may be preheated by exchanging heat with high-temperature exhaust gas generated during power generation in the woody biomass power generation facility 13 nearby.

Further, the preheated air supply duct 38 is provided with a preheated air temperature sensor 40 for detecting the temperature of the preheated air preheated by the heat exchanger 37, an air volume sensor 41 for detecting the air volume of the preheated air, and the burner 28. A preheated air amount adjustment damper 42 for adjusting the amount of preheated air to be supplied is provided.

As the preheating temperature increases, the oxygen concentration of the preheated air decreases due to thermal expansion. The opening is adjusted and controlled to supply a sufficient amount of air (oxygen) to the burner 28 to enable stable combustion. Instead of using the preheated air amount adjusting damper 42, the air blower 39 may be of an inverter type, and the blowing amount of the air blower 39 may be directly adjusted.

In the middle of the heavy tar supply pipe 43 for supplying the heavy tar from the heavy tar storage tank 21 to the injection nozzle 27 of the burner 28, a supply pump 44 and a heavy tar supply pump 44 according to the burner combustion amount are installed. A heavy tar supply amount adjustment valve 45 for adjusting the supply amount is provided.

The heavy tar storage tank 21 is equipped with a hot water heater 46. The hot water heater 46 heats and maintains the heavy tar temperature at about 70 to 90° C., and the viscosity of the heavy tar, which is highly viscous at room temperature, is increased. is lowered so that the powder can smoothly flow to the injection nozzle 27 of the burner 28 and be easily atomized at the time of injection.

Reference numeral 47 in the figure denotes a gas cylinder for storing propane gas to be supplied to the preheating burner 29 as fuel. An on-off valve 49 is provided in the middle of the pipe 48 . As the fuel for the preheating burner 29, LNG, heavy oil, kerosene, etc. can be used in place of the propane gas.

The water-containing light tar storage tank 22 is also provided with a hot water heater 50, and the water-containing light tar storage tank 22 is heated by the water heater 50 to evaporate the contained moisture and volatilize some tar. It is configured to separate into steam containing components and light tar. Water-containing light tar, which contains a large amount of water, is more flame-retardant than heavy tar, making it unsuitable as burner fuel. After the tar is separated into 2 parts, it is introduced individually near the burner flame in the furnace main body 25 in a high-temperature atmosphere (so as to be directly exposed to the flame), so that the tar can be sufficiently burned.

51 in the figure is a light tar supply pipe that supplies the light tar separated by heating in the water-containing light tar storage tank 22 to the injection nozzle 32 of the light tar introduction pipe 33 in the middle of the furnace body 25. A supply pump 52 and a light tar temperature sensor 53 for detecting the temperature of the light tar are provided in the middle of the tar supply pipe 51 .

When the temperature of the light tar reaches 100° C. or higher, some water remaining in the light tar evaporates in the light tar supply pipe 51, condensing the tar component and possibly clogging the pipe. Therefore, based on the temperature detected by the light tar temperature sensor 53 of the light tar supply pipe 51, the flow rate adjustment valve 54 for adjusting the amount of hot water supplied to the hot water heater 50 is adjusted so that the detected temperature is maintained at, for example, approximately 70 to 90°C. It is configured to control opening and closing at the same time.

In the figure, 55 is a steam supply pipe that supplies steam containing some volatile tar components heated and separated in the water-containing light tar storage tank 22 to the steam introduction pipe 30 at the base end of the furnace body 25. A blower 56 and a channel switching valve 57 such as a three-way valve are provided in the middle of the supply pipe 55 . Further, 58 in the figure is a pyrolysis gas storage tank 16 that stores the pyrolysis gas generated in the woody biomass power generation facility 13 and the flow path switching valve 57 on the way of the steam supply pipe 55. This is the gas supply pipe.

The flow path switching valve 57 switches the flow path so as to communicate with the upper end side of the water-containing light tar storage tank 22 during steady operation of the combustion treatment furnace 23, and the steam containing the volatile components of tar is transferred to the furnace body under a high-temperature atmosphere. 25 so that the volatile tar components in the steam can be burned. On the other hand, when the combustion treatment furnace 23 is started (during preheating operation), the flow path is made to communicate with the pyrolysis gas storage tank 16 of the nearby woody biomass power generation facility 13 via the pyrolysis gas supply pipe 58 . By switching, part of the pyrolysis gas for power generation generated in the woody biomass power generation facility 13 is supplied into the furnace body 25 and blown into the flame of the preheating burner 29 for co-firing, and is used as an auxiliary fuel during the preheating operation. As a result, it is possible to quickly complete the preheating operation and switch to the steady operation while suppressing the amount of propane gas used as fuel for the preheating burner 29 .

As shown in FIG. 2, the pyrolysis gas storage tank 16 includes a main pyrolysis gas supply pipe 18 for supplying the stored pyrolysis gas to the gas engine 17 for power generation, and a combustion gas for preheating operation. A sub pyrolysis gas supply pipe 58 for supplying to the processing furnace 23 is also provided. The pyrolysis gas can be supplied to both of the processing furnaces 23 at the same time, and can be used for preheating the combustion processing furnace 23 while generating power.

Further, in this embodiment, the pyrolysis gas supply pipe 58 is connected to a channel switching valve 57 in the middle of the steam supply pipe 55, and the pyrolysis gas supplied from the pyrolysis gas storage tank 16 is temporarily switched to the steam supply pipe 55. The pyrolysis gas supply pipe 58 is directly connected to the furnace body 25, and the pyrolysis gas is supplied from the pyrolysis gas storage tank 16. A configuration in which the gas is directly supplied into the furnace body 25 can also be used.

Reference numeral 59 in the figure is a tar combustion controller for controlling the operation of the combustion treatment furnace 23 and its accessory devices, and is an input/output unit for inputting/outputting detected values from the various sensors and control signals to each device. , a setting storage unit for registering various setting values, and a control unit for executing various controls based on these various detection values and setting values.

When treating woody tar-containing wastewater generated in the woody biomass power generation facility 13, the generated tar-containing wastewater is put into the wastewater storage tank 19 near the woody biomass power generation facility 13 as needed and stored. When the wastewater storage tank 19 is substantially filled with tar-containing wastewater, the adjacent specific gravity separator 20 separates the relatively light water-containing light tar and the relatively heavy heavy tar by specific gravity. The light tar and the heavy tar are put into the water-containing light tar storage tank 22 and the heavy tar storage tank 21, respectively, and stored separately.

When the wet light tar and heavy tar stored in the wet light tar storage tank 22 and the heavy tar storage tank 21 are to be treated in the combustion treatment furnace 23, the hot water heater of the wet light tar storage tank 22 is first used. Hot water is supplied to 50, and the stored water-containing light tar is heated to about 70 to 90°C to evaporate the contained water, and the water vapor containing some tar volatile components and light tar are separated by heating. Hot water is also supplied to the hot water heater 46 of the heavy tar storage tank 21 to heat and maintain the heavy tar at approximately 70 to 90° C., thereby smoothly supplying the heavy tar, which is highly viscous and flame-retardant at room temperature. Reduce the viscosity to the extent possible and easy to atomize.

Next, propane gas is supplied to the preheating burner 29 and ignited for combustion to start the preheating operation. and supply pyrolysis gas derived from woody biomass into the furnace main body 25 and blowing it into the burner flame of the preheating burner 29 for co-firing and using it as an auxiliary fuel during the preheating operation. As a result, the preheating operation can be completed early while suppressing the amount of propane gas used by the preheating burner 29 .

Then, when the inside of the furnace body 25 is preheated to some extent and the temperature of the exhaust gas discharged from the exhaust duct 35 reaches approximately 500° C. or higher, the blower 39 is driven to supply combustion air (outside air). The heavy tar is preheated to about 200 to 300° C. by exchanging heat with the high-temperature exhaust gas in the heat exchanger 37 and then supplied to the burner 28 through the preheated air supply duct 38 . According to experimental data conducted by the present inventors, it has been confirmed that if the exhaust gas temperature is approximately 500° C. or higher, the room temperature combustion air can be preheated to approximately 200 to 300° C. after heat exchange.

Next, the supply pump 44 of the heavy tar supply pipe 43 and the compressor 26 are driven to inject the heavy tar together with the compressed air from the two-fluid injection nozzle 27 while atomizing it. Based on the detected values of the preheated air temperature sensor 40 and the air volume sensor 41, and the combustion amount of the burner 28, the opening degree of the preheated air amount adjustment damper 42 is adjusted after considering the effect of thermal expansion according to the preheated air temperature. The burner 28 is ignited and burned while being adjusted and controlled, and the preheating burner 29 is extinguished.

The supply of pyrolysis gas from the pyrolysis gas storage tank 16 of the woody biomass power generation facility 13 may be stopped in accordance with the extinguishing timing of the preheating burner 29. If the preheating operation is to be completed early by heating, the pyrolysis gas is continuously supplied into the furnace main body 25 even after the preheating burner 29 is extinguished, and the burner 28 located near the preheating burner 29 is used. It is good to blow it into the flame of the flame and co-fire it.

Then, when the exhaust gas temperature detected by the exhaust gas temperature sensor 36 reaches approximately 850° C. at which the volatile tar components and light tar fine particles can be completely combusted, the preheating operation is terminated and the steady operation is started.

When it shifts to steady operation, the flow path of the flow path switching valve 57 is switched to the side communicating with the upper end of the water-containing light tar storage tank 22, and some tar volatile components separated by heating in the water-containing light tar storage tank 22 are included. Steam is introduced from the base end of the furnace body 25 of the combustion treatment furnace 23 into the furnace body 25 from the tangential direction through the steam supply pipe 55 and the steam introduction pipe 30, and the water-containing light tar storage tank 22 bottom side. By driving the supply pump 52 of the light tar supply pipe 51 and the compressor 31, and atomizing the light tar together with the compressed air from the two-fluid system injection nozzle 32, the light tar is atomized into the furnace main body 25 from the middle part of the furnace main body 25. Introduce.

Then, the steam introduced from the base end of the furnace body 25 in a high temperature atmosphere of approximately 850° C. or higher flows down in the downstream direction while swirling along the surface of the heat storage casters 24 that are the inner walls of the furnace body 25. During this time, the tar volatile components are brought into close contact with the combustion gas from the burner 28, so that the tar volatile components, which are difficult to combust due to the small amount contained in the water vapor, are efficiently combusted. Further, the light tar fine particles injected/introduced from the intermediate portion of the furnace body 25 are easily atomized in the high-temperature furnace body 25, and in that state, come into contact with the combustion gas from the burner 28 in the same manner as described above. Well combusted.

As described above, the present invention has been developed in the past as a by-product of woody biomass power generation facilities, and there is not much effective use and there is a large amount of surplus tar-containing tar that requires a large amount of fossil fuel even if it is to be incinerated as it is. Focusing on the fact that the wastewater contains heavy tar that can be effectively used as burner fuel, the tar-containing wastewater is gravity-separated into heavy tar and water-containing light tar, and the heavy tar is converted into fossils. It is effectively used as fuel for the burner 28 of the combustion treatment furnace 23 in place of the fuel, while the remaining flame-retardant water-containing light tar, which is unsuitable as burner fuel, is further heated and separated into steam containing tar volatile components and light tar. After that, by introducing them individually into the furnace body 25 of the combustion treatment furnace 23, the tar component can be efficiently burned. As a result, tar-containing wastewater, which has been a bottleneck in the operation of woody biomass power generation facilities, can be appropriately treated while reducing the amount of fossil fuels used, contributing to the spread of woody biomass power generation facilities, which are facilities that reduce environmental impact. become a thing.

Further, the combustion treatment furnace 23 is installed in the vicinity of the woody biomass power generation facility 13, and part of the pyrolysis gas for power generation generated in the woody biomass power generation facility 13 is supplied to the combustion treatment furnace 23 to If it is used as an auxiliary fuel for preheating operation, the preheating operation can be completed early while suppressing the amount of fossil fuel used during preheating operation, and the effect of switching to steady operation can be expected, which is more preferable. becomes.

INDUSTRIAL APPLICABILITY The present invention can be widely used as a method for treating woody tar-containing wastewater generated as a by-product in a woody biomass power generation facility.

2 Gasification process 3 Gas refining process 4 Power generation process 5 Wastewater storage process 6 Gravity separation process 7 Tar storage process 8 Heavy tar storage process (tar storage process)
9 … Water-containing light tar storage step (tar storage step)
DESCRIPTION OF SYMBOLS 10... Heating separation process 11... Tar combustion process 12... Combustion air preheating process 13... Woody biomass power generation facility 14... Gasification furnace (woody biomass power generation facility)
15... Gas purifier (woody biomass power generation facility)
16 Pyrolysis gas storage tank (woody biomass power generation facility)
17 … Gas engine (Woody biomass power generation facility)
Reference Signs List 18, 58 Pyrolysis gas supply pipe 19 Waste water storage tank 20 Specific gravity separator 21 Heavy tar storage tank 22 Light tar storage tank 23 Combustion treatment furnace 24 Caster 25 Furnace body 26, 31 Compressor 27 , 32... injection nozzle 28... burner 29... preheating burner 30... water vapor introduction pipe 33... light tar introduction pipe 34... reduced diameter portion 35... exhaust duct 37... heat exchanger 38... preheated air supply duct 39... blower 40... preheated air Temperature sensor 41 Air volume sensor 42 Preheated air volume adjustment damper 43 Heavy tar supply pipe 46, 50 Hot water heater 51 Light tar supply pipe 55 Water vapor supply pipe 57 Flow path switching valve 59 Tar combustion controller

Claims (4)

A method for treating woody tar-containing wastewater generated in a woody biomass power generation facility, comprising: a wastewater storage step of storing the tar-containing wastewater in a tank; A tar storage step of storing the gravity-separated heavy tar and water-containing light tar in separate tanks, and heating the water-containing light tar to evaporate the water to form light tar. A heat separation step for separating the tar into water vapor containing volatile components, and the light tar and the water vapor are individually introduced into a furnace body of a combustion treatment furnace equipped with a burner for burning the heavy tar, and the light tar and the water vapor are burned. A tar combustion treatment step and a combustion air preheating step of preheating combustion air supplied to the burner to a predetermined temperature, wherein heavy tar separated from tar-containing wastewater is heated to a predetermined temperature and preheated for combustion While supplying air to the burner of the combustion treatment furnace, the heavy tar is burned as fuel for the burner, and the light tar separated from the water-containing light tar and steam are introduced into the furnace body for combustion treatment. A method for treating woody tar-containing wastewater generated at a woody biomass power generation facility. 2. The method according to claim 1, wherein during preheating operation of said combustion treatment furnace, pyrolysis gas for power generation generated in said woody biomass power generation facility is blown into a furnace body of said combustion treatment furnace and burned as auxiliary fuel. A method of treating woody tar-containing wastewater generated at a woody biomass power generation facility in Japan. 3. The treatment of woody tar-containing wastewater generated in a woody biomass power generation facility according to claim 1 or 2, characterized in that the combustion air of said burner is preheated by exchanging heat with the exhaust gas discharged from the combustion treatment furnace. Method. 4. Woody tar generated in a woody biomass power generation facility according to any one of claims 1 to 3, characterized in that steam separated by heating from water-containing light tar is introduced in the tangential direction of the furnace body of the combustion treatment furnace. Methods for treating contaminated wastewater.

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