JP4540628B2 - Waste gasifier - Google Patents

Description

  The present invention relates to a waste gasifier, and more specifically, to a waste gasifier that thermally decomposes and gasifies waste.

  As a method of treating waste such as municipal waste, woody biomass, car shredder dust, or industrial waste, a method of effectively using gas generated by pyrolyzing waste (hereinafter referred to as product gas) as fuel Has been proposed (for example, Patent Document 1). According to this, a waste bed is thrown into a gasification furnace, a packed bed is formed, an oxidant is supplied from the bottom to cause partial combustion, and the waste is pyrolyzed by the heat of the partial combustion. A gasification furnace has been proposed. In other words, a combustion zone, a pyrolysis zone, and a dry zone are formed in the packed bed of waste filled in the furnace height direction, and the waste is pyrolyzed in the pyrolysis zone by the heat of the combustion zone, so that By drying the waste in the dry zone, the waste is continuously thermally decomposed. The product gas generated by such a waste gasifier is relatively clean because fly ash and the like in the gas are removed in the process of raising the drying zone.

Special Table 2000-517409

  By the way, the product gas obtained by thermally decomposing waste contains moisture in the waste and impurities such as tar generated by combustion or pyrolysis. The moisture in the product gas has the disadvantage of reducing the amount of combustion heat generated per unit gas amount. Further, impurities such as tar in the generated gas have a problem of adversely affecting a heat engine using this as a fuel.

  However, in the prior art described in Patent Document 1, no consideration is given to removal of impurities such as moisture and tar contained in the product gas.

  Therefore, since impurities such as moisture and tar in the product gas condense when the temperature of the product gas is lowered, for example, by sprinkling water into the product gas and cooling it, the impurities such as moisture and tar in the product gas It is conceivable to remove impurities by condensing them. However, in order to condense the moisture and tar in the product gas at a high temperature (for example, 700 to 800 ° C.), a large amount of water is required, so that there is a problem that the wastewater treatment facility becomes large.

  This invention makes it a subject to provide the waste gasifier which can remove impurities, such as a water | moisture content and tar contained in the product gas of a gasification furnace, without enlarging wastewater treatment equipment.

  In order to solve the above-mentioned problems, the waste gasifier of the present invention is generated by moving a bed type gasification furnace for thermally decomposing waste and sprinkling cooling water into the generated gas generated in the gasification furnace. A condensing tower for condensing impurities such as water and tar contained in the gas, a condensate tank into which the condensate condensed by the condensing tower flows, and a condensate in the condensate tank are circulated and supplied to the watering nozzle of the condensing tower A cooling water circulation channel provided with a pump, and a circulating cooling water purification tower provided in the cooling water circulation channel and filled with an adsorbent that adsorbs impurities in the cooling water.

  According to this, since impurities such as water and tar are condensed in the condensation tower, they can be removed from the product gas. In particular, since the condensed condensed water is circulated and reused as cooling water, the water required for the cooling water can be significantly reduced, so that the waste water treatment facility can be downsized. Further, by removing impurities (organic components) contained in the condensed water by the circulating cooling water purification tower with an adsorbent (for example, activated carbon), it is possible to suppress an increase in the concentration of impurities contained in the circulating cooling water.

  Moreover, it is preferable to provide a pH adjusting means for making the pH of the condensate in the condensate tank near neutral. Thereby, the adsorption capacity of the adsorbent (for example, activated carbon) of the circulating cooling water purification tower provided in the cooling water circulation channel that circulates and uses the condensate can be maintained.

  In addition, a tar adsorption tower in which the cooling water circulation passage upstream of the circulating cooling water purification tower is filled with noncombustible particulate matter, and an oil water separation tank in the cooling water circulation passage between the tar adsorption tower and the circulating cooling water purification tower It is desirable to provide Thereby, since tar and oil in the circulating cooling water are removed, the load on the circulating cooling water purification tower can be reduced, and the life of the adsorbent can be extended.

  Further, when the gasification furnace is filled with non-combustible particulate matter in addition to waste, gasification is stabilized and gasification efficiency is improved. In this case, the incombustible granular material of the tar adsorption tower can be taken out and introduced as the incombustible granular material of the gasifier. Thereby, the gas adhering to the nonflammable granular material can be gasified, and the gasification efficiency is improved. In other words, the noncombustible granular material used in the gasification furnace can be effectively used as a tar adsorbent.

  Moreover, the oil component isolate | separated by the oil-water separation tank can be thrown into a gasification furnace. According to this, it is possible to treat the oil component without separately treating it, and to improve the gasification efficiency of the gasifier.

  Further, a reforming tower for reforming and gasifying the tar in the product gas can be provided between the gasification furnace and the condensation tower. Thereby, since the tar contained in the product gas discharged | emitted from a gasification furnace can be gasified, the load of a tar adsorption tower can be reduced. In addition, the condensing tower includes a first cooling tower that sprinkles cooling water into the product gas and lowers the temperature to a set temperature, and water that sprinkles cooling water into the product gas whose temperature has been lowered by the first cooling tower. And a second cooling tower that condenses impurities such as tar. According to this, condensation of impurities such as water and tar can be effectively performed.

  According to the waste gasification apparatus of the present invention, impurities such as water and tar contained in the gas generated in the gasification furnace can be removed without increasing the size of the waste water treatment facility.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an overall configuration diagram of the waste gasifier according to this embodiment. In the present embodiment, woody biomass will be described as an example of waste.

  The waste gasifier 1 of this embodiment is configured as shown in FIG. A hopper 19 for introducing woody biomass and a hopper 21 for introducing non-combustible pellets 53 are installed at the top of the vertical-type moving bed type gasification furnace 3. Dampers are provided at the inlets of the hopper 19 and the hopper 21, respectively. The woody biomass cut out from the hopper 19 is conveyed by, for example, a screw conveyor and supplied into the furnace, while the incombustible pellet 53 is supplied into the furnace by, for example, a rotary feeder.

  The gasification furnace 3 is provided with a discharge port for discharging the generated gas on the top side wall, and an oxidant supply path 23 for supplying an oxidant and a water vapor supply path 25 for supplying water vapor are connected to the bottom and side walls. Yes. At the bottom of the gasification furnace 3, an extractor (not shown) for discharging the combustion residue and the non-combustible pellets 53 is provided.

  Wood biomass and incombustible pellets are charged into the hopper 19 and the hopper 21, respectively, and a packed bed is formed in the furnace. When the oxidant is introduced from the oxidant supply path 23, the woody biomass partially burns to form a combustion zone in the packed bed. A pyrolysis zone is formed in the upper part of the combustion zone, and a dry zone is further formed in the upper part. In the pyrolysis zone, woody biomass is pyrolyzed to produce combustible pyrolysis gas and carbon (char). This char flows down to the combustion zone and is burned. Further, a part of the char generated in the thermal decomposition zone reacts with the water vapor supplied from the water vapor supply path 25 to generate water gas (CO, H 2).

  The product gas, which is a mixture of pyrolysis gas and water gas generated in this way, flows through the gaps in the packing and rises, passes through the drying zone and dries the woody biomass, etc. to reduce the temperature. And discharged from the discharge port at the top of the gasification furnace 3.

  On the other hand, the woody biomass pyrolyzed in the pyrolysis zone becomes ash that has been pyrolyzed and burned in the combustion zone. These flow down the cooling zone formed in the lower layer of the combustion zone, and are discharged out of the furnace by an extractor at the bottom of the furnace. In addition, the combustion residue discharged from the furnace, incombustible pellets, and the like are subjected to separation processing.

  Incidentally, the product gas discharged from the gasification furnace 3 contains impurities such as tar produced by combustion or thermal decomposition. Therefore, the product gas is introduced into the reforming furnace 5 and heat-treated at a high temperature, whereby the tar in the gas is thermally decomposed into a low-molecular decomposition gas.

  The product gas reformed in the reforming furnace 5 is guided to the first cooling tower 7. The first cooling tower 7 sprinkles cooling water from the water spray nozzle 29 into the product gas introduced from the reforming furnace 5, thereby setting the temperature of the reformed gas (for example, 700 to 800 ° C.) to a set temperature ( For example, the temperature is lowered to 150 ° C.

  The product gas whose temperature has been lowered is guided to the second cooling tower 9. The second cooling tower 9 condenses and removes impurities such as water vapor and tar contained in the generated gas by sprinkling cooling water from the water spray nozzle 31 into the generated gas introduced from the first cooling tower 7. Here, the sprayed cooling water flows into the condensate tank 35 as a condensate 33 containing impurities such as condensed water of water vapor and tar. On the other hand, the product gas from which impurities such as water and tar are removed in the second cooling tower 9 is guided to the gas cleaning tower 11. The gas scrubbing tower 11 passes the product gas introduced from the second cooling tower 9 through a packed bed filled with a packing such as rahiscilling, and sprinkles the alkali scrubbing water from the sprinkling nozzle 37 to thereby generate the product gas. Neutralize the hydrogen chloride in it. Here, the sprinkled alkaline cleaning water flows into the cleaning water tank 43. The product gas obtained by neutralizing hydrogen chloride in the product gas is guided to the demister 13.

  The generated gas introduced into the demister 13 is discharged by the induction blower 15 after droplets in the gas are removed here. The product gas discharged from the demister 13 is used as fuel for the diesel engine 17 via the induction blower 15. Note that a branch pipe connected to the flare stack is provided on the discharge side of the induction blower 15, and a part of the generated gas is appropriately burned.

  In this way, the product gas discharged from the gasification furnace 3 is reformed in the reforming furnace 5, and then impurities such as water and tar contained in the product gas enter the second cooling tower 9. Removed. Thereby, it can supply to a heat engine, without reducing the combustion calorific value per unit gas amount of product gas. Moreover, it does not adversely affect the heat engine using the generated gas as fuel.

  In addition, the supply destination of the product gas processed in the waste gasification apparatus 1 of this embodiment is not limited to the diesel engine 17, and may be a heat engine such as a gas turbine or a boiler.

  Next, the 1st cooling tower 7 and the 2nd cooling tower 9 which are the characteristics of this invention are demonstrated in detail with reference to FIG. As shown in FIG. 2, in the present embodiment, the temperature of the condensing tower is lowered by the first cooling tower 7 that sprinkles cooling water into the product gas to lower the temperature to the set temperature, and the first cooling tower 7. The generated product gas is divided into a second cooling tower 9 that sprinkles cooling water and condenses impurities such as water and tar.

  The first cooling tower 7 introduces the generated gas discharged from the reforming furnace 5 from the upper part of the tower and discharges it from the lower part of the tower, and sprays cooling water downward from a watering nozzle 29 provided in the upper part of the tower. It is made to make it contact with product gas.

  The second cooling tower 9 introduces the generated gas discharged from the first cooling tower 7 from the lower part of the tower and discharges it from the upper part of the tower, and lowers the cooling water from a watering nozzle 31 provided in the upper part of the tower. It is structured such that it is sprayed with water and brought into contact with the product gas. Here, the cooling water sprayed from the water spray nozzle 31 enters a condensate tank 35 provided under the second cooling tower 9 as a condensate 33 containing impurities such as condensed water of water vapor and tar in the generated gas. Inflow.

  The condensate tank 35 includes a drainage channel 52 for discharging the condensate 33 to the wastewater treatment facility, and an inflow channel 54 that guides the condensate 33 to the cooling water circulation channel 47. The pump 45 sucks the condensate 33 in the condensate tank 35 through the inflow passage 54 and circulates the condensate 33 as cooling water in the cooling water circulation passage 47. The cooling water circulation channel 47 includes a pump 45 and a circulating cooling water purification tower 51, circulates the condensate 33 sent from the pump 45, and supplies it to the water spray nozzle 31 as cooling water. The circulating cooling water purification tower 51 introduces the condensate 33 introduced by the pump 45 from the upper part of the tower and discharges it from the lower part. Further, the adsorbent 49 packed in the tower adsorbs and removes impurities such as organic components (particularly organic acids) such as tar in the condensate. For the adsorbent 49, for example, activated carbon can be used.

  That is, the temperature of the generated gas (for example, 700 to 800 ° C.) is lowered to the set temperature (for example, 150 ° C.) by the cooling water sprayed by the first cooling tower 7. Next, impurities such as water vapor and tar contained in the product gas are condensed and removed by the cooling water sprayed by the second cooling tower 9. The cooling water sprayed by the second cooling tower 9 becomes a condensate 33 containing impurities such as condensed water of water vapor and tar in the generated gas and flows into the condensate tank 35. The condensate 33 accumulated in the condensate tank 35 flows into the cooling water circulation passage 47 via the pump 45 and is supplied as cooling water to the water spray nozzle 31 by the cooling water circulation passage 47. In this circulation process, impurities contained in the cooling water are removed by the circulating cooling water purification tower 51.

  In this way, in the second cooling tower 9, impurities such as water vapor and tar in the generated gas are condensed and removed, and the condensate 33 is circulated as cooling water and reused, so that it is necessary for the cooling water. Therefore, waste water treatment equipment can be downsized. Moreover, since the impurities contained in the cooling water are removed by the circulating cooling water purification tower 51, an increase in the concentration of the impurities contained in the circulating cooling water can be suppressed.

  The condensate tank 35 includes a pH measuring device (not shown) that is a pH adjusting unit and an alkaline water injection pump. As a result, the pH of the condensate 33 is lowered by the hydrogen chloride contained in the product gas and becomes an acidic condensate 33. It is preferable to adjust the pH of the condensate 33 to near neutrality by adjusting the pH. Thereby, when activated carbon is used for the adsorbent of the circulating cooling water purification tower 51 provided in the cooling water circulation channel that circulates and uses the condensate, the adsorption capability of the activated carbon can be maintained. That is, in order to efficiently adsorb and remove organic components with activated carbon, it is preferable to set the pH to the acidic side of 2-3. However, if the acidity of the condensate is strong, it is not preferable because the crisis and piping are corroded. Moreover, when it is alkalinized, the adsorption ability of activated carbon cannot be exhibited sufficiently. Therefore, in order not to greatly impair the adsorption capacity of the activated carbon, it is preferable to set the pH of the condensate 33 to be near neutral. Temporarily, in order to increase the adsorption capacity of activated carbon, it is adjusted to acidic at the inlet of the circulating cooling water purification tower 51 and returned to neutral at the outlet of the circulating cooling water purification tower 51 to suppress corrosion of equipment and piping. However, it is not preferable since the pH adjusting device and the chemical solution are doubled.

  Further, since the condensate 33 in the condensate tank 35 continues to increase during operation, a part of the condensate 33 must be discharged to the drainage system. The burden can be reduced.

  Further, a tar adsorption tower 55 in which the cooling water circulation passage 47 on the upstream side of the circulating cooling water purification tower 51 is filled with incombustible pellets 53 that are incombustible granular materials, and the tar adsorption tower 55 and the circulating cooling water purification tower 51 are provided. An oil / water separation tank 57 is provided in the cooling water circulation passage 47. Thereby, the tar contained in the condensate 33 is adsorbed and removed by the incombustible pellets 53, and then the oil contained in the condensate 33 is removed by the oil / water separation tower 57. That is, since the tar and oil in the condensate 33 circulating as cooling water are removed and flow into the circulating cooling water purification tower 51, the load on the circulating cooling water purification tower 51 can be reduced. Thereby, the lifetime of the adsorbent 49 (for example, activated carbon) of the circulating cooling water purification tower 51 can be extended.

  Moreover, when the gasification furnace 3 is filled with non-combustible pellets 53 in addition to the woody biomass, gasification is stabilized and gasification efficiency is improved. In this case, the incombustible pellets 53 of the tar adsorption tower 55 can be taken out and introduced as the incombustible pellets 53 of the gasification furnace 3. Thereby, the gas adhering to the incombustible pellet 53 can be gasified, and the gasification efficiency is improved.

  Incombustible pellets 53 include light pellets (for example, granular pumice) and hard pellets (for example, granular ceramics). The light pellet is a pellet having a low heat-resistant temperature that is used when the gasification furnace 3 is started. On the other hand, the hard pellet is a pellet having a high heat resistance temperature that can be used while the gasification furnace 3 is in operation. The incombustible pellets 53 used in the tar adsorption tower 55 are desirably hard pellets that can be used while the gasification furnace 3 is in operation.

  Moreover, the oil component isolate | separated by the oil-water separation tank 57 can be collect | recovered, it can descend | fall to wood type biomass, and can be thrown into the gasifier 3 with wood type biomass. According to this, the oil component can be processed without being separately processed, and the gasification efficiency of the gasification furnace 3 can be improved.

  A reforming furnace 5 is provided between the gasification furnace 3 and the first cooling tower 7, which is a reforming tower for reforming and gasifying the tar in the generated gas. Thereby, since the tar contained in the product gas discharged from the gasification furnace 3 can be gasified, the load on the tar adsorption tower 55 can be reduced, and the usage time of the non-combustible pellets 53 of the tar adsorption tower 55 can be reduced. Can be lengthened.

  Moreover, since the condensing tower is divided into the first sprinkling tower 7 and the second sprinkling tower 9, it is possible to effectively condense impurities such as water and tar.

Further, a radiator 59 is provided in the cooling water circulation passage 47 on the downstream side of the circulating cooling water purification tower 51. Thereby, since the temperature of the cooling water sprayed from the water spray nozzle 31 can be reduced, impurities such as water and tar can be effectively condensed.

Further, a cooling water passage 61 for returning the cooling water to the condensate tank 35 is provided in the cooling water circulation passage 47 on the downstream side of the radiator 59 , and the cooling water is provided in the cooling water circulation passage 47 on the downstream side of the cooling water passage 61 . A valve 63 for adjusting the amount and a valve 65 for returning to the cooling water channel 61 and adjusting the amount of cooling water are provided. Thereby, the quantity of the cooling water supplied to the watering nozzle 31 can be adjusted. Further, the temperature of the product gas discharged from the second cooling tower 9 is measured by a temperature sensor such as a thermocouple, and the valves 63 and 65 are adjusted via the transmitter 67 and the like, so that The temperature can be adjusted.

In addition, by providing a flow meter 69 in the cooling water circulation passage 47 on the downstream side of the valve 63, the actual amount of cooling water supplied to the watering nozzle 31 is monitored.

  Moreover, although this embodiment demonstrated the woody biomass as an example as a waste material, this invention is not limited to this. For example, the same effect can be obtained by applying municipal waste, car shredder dust, industrial waste, or the like.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram of the whole waste gasification apparatus of Embodiment 1 of this invention. It is a block diagram of the 1st, 2nd cooling tower of the waste gasification apparatus of Embodiment 1. FIG.

Explanation of symbols

3 Gasifier 9 Second Cooling Tower 31 Watering Nozzle 33 Condensate 45 Pump 47 Cooling Water Circulation Channel 49 Adsorbent 51 Circulating Cooling Water Purification Tower

Claims (7)

Waste and gasifier pyrolyzing moving bed and a condensation column to condense the water and tar contained in the produced gas with water spray cooling water to the produced gas produced in the gasification furnace, the A condensate tank into which the condensate condensed by the condensing tower flows, a cooling water circulation passage provided with a pump for circulatingly supplying the condensate in the condensate tank to the watering nozzle of the condensing tower, and the cooling water circulation flow A waste gasifier comprising a circulating cooling water purification tower provided in a passage and filled with an adsorbent that adsorbs impurities in the circulating cooling water.   2. The waste gasifier according to claim 1, further comprising pH adjusting means for adjusting the pH of the condensate in the condensate tank to near neutral.   The waste gasification apparatus according to claim 1 or 2, wherein a tar adsorption tower filled with incombustible particulates is provided in the cooling water circulation passage upstream of the circulating cooling water purification tower. Waste gasifier.   4. The waste gasification apparatus according to claim 3, wherein an oil / water separation tank is provided in the cooling water circulation passage between the tar adsorption tower and the circulating cooling water purification tower. .   4. The waste gasification apparatus according to claim 3, wherein the gasification furnace is filled with incombustible particulates in addition to the waste, and takes out the incombustible particulates of the tar adsorption tower. Waste gasifier characterized by being introduced as non-combustible granular material.   5. The waste gasifier according to claim 4, wherein the oil component separated in the oil / water separation tank is put into the gasification furnace. The waste gasifier according to claim 1, wherein a reforming tower for reforming and gasifying the tar in the product gas is provided between the gasification furnace and the condensation tower, and the condensation tower is provided. A first cooling tower that sprinkles cooling water into the product gas to lower the temperature to a set temperature, and water and water that sprinkles cooling water into the product gas whose temperature has been lowered by the first cooling tower. waste gasification apparatus characterized by comprising a second cooling tower for condensing tar.

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