JP2006317089A - Gasification melting method and gasification melting device for combustibles - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gasification melting method and a gasification melting device for manufacturing inflammable gas of high quality with high calorific power and little variation of component composition and calorific power. <P>SOLUTION: (1) The gasification melting method for combustibles has steps of carrying out (a) operation of cooling produced gas produced in gasification melting treatment by spraying cooling liquid to the produced gas produced in the gasification melting treatment, using produced gas subjected to cleaning treatment, and/or (b) operation of backwashing a bag filter for removing dust in the produced gas produced in gasification melting treatment, using the produced gas subjected to cleaning treatment. (2) The gasification melting device for carrying out the gasification melting method in (1) comprises produced gas recycling piping 14 for supplying the produced gas F finished with cleaning treatment to a gas cooling device 3 and/or the bag filter 6. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention gas-treats high-temperature combustible gas generated in a gasification melting furnace that gasifies and melts combustibles such as waste at a high temperature exceeding 1000 ° C., and can be used as a high-quality combustible gas such as fuel. The present invention relates to a gasification melting method and an apparatus therefor.

  In the treatment of combustibles such as waste and thermal recycling, simple incineration or incineration waste heat is collected by steam, and the turbine is rotated to generate electricity. However, in recent years, more efficient and less polluting. As thermal recycling, there is a need to develop a method and apparatus for converting a combustible material such as waste into a combustible gas by gasifying and melting it at a high temperature and using it as a fuel or chemical raw material.

  The gas conversion process for gas treatment of high-temperature combustible gas generated in a gasification melting furnace that gasifies and melts combustibles such as waste at a high temperature exceeding 1000 ° C. and makes it usable as fuel, etc. These are constituted by the following three types of processes.

1) Gasification and melting of combustibles such as waste at a high temperature exceeding 1000 ° C 2) Step of cooling the gas generated in the gasification melting furnace to room temperature or below a certain temperature 3) Purifying the gas after cooling In the gasification and melting step described above, combustible materials such as waste are charged into a furnace maintained at a high temperature of 1000 ° C. or higher, and gasified and melted at a high temperature to generate a combustible product gas. At this time, the incombustible component becomes molten slag and is discharged out of the furnace through a discharge port provided at the lower part of the gasification melting furnace, separately from the generated gas.

  In the gas cooling process described above, gas quenching that rapidly cools and cools continuously without re-synthesizing dioxins, etc. by spraying the cooling liquid such as water into fine particles and spraying them on the product gas in the container. Many cooling towers are used. In the spraying of the cooling liquid in the gas quenching decelerating tower, the gas temperature is rapidly lowered using the heat of evaporation of the cooling liquid to be sprayed. Therefore, the smaller the particle size of the cooling liquid, the greater the effect. .

  Therefore, a method of forming fine cooling droplets of 100 μm or less by using a two-fluid spray nozzle that ejects gas and liquid is employed. As the gas used in the two-fluid spray nozzle, nitrogen gas, which is inert and inexpensive, is usually used. The reason is that the gas generated in the gasification and melting furnace is a flammable gas. Therefore, when a gas containing oxygen is injected into the gas quenching and cooling tower, combustion or explosion occurs in the gas quenching and cooling tower. This is because there is a risk of waking up.

  In the gas cleaning process, a bag filter is generally employed. The bag filter is a device that removes dust contained in the gas by allowing the gas to pass through the filter cloth formed in a bag shape, and the filter cloth clogs with use. Therefore, a “backwashing process” is provided for removing dust adhering to the filter cloth and eliminating clogging by passing clean gas in the direction opposite to the gas flow during normal operation. . Also in this backwashing process, nitrogen gas is used for the same reason as in the case of the gas quenching and cooling tower.

  As a gasification melting technique including a gasification melting step (gasification melting furnace), a gas cooling step (gas cooling device), and a gas cleaning step (dust removal device), for example, Patent Document 1 discloses a gasification melting furnace and a gas. A chemical melting method is disclosed. Here, the disclosed technology is a vertical gasification melting furnace that burns waste and collects organic matter in the waste as energy gas, and collects ash and metal as melt, and gas for cooling the gas The present invention relates to a gasification and melting apparatus including a cooling facility and a dust removal facility, and a gasification and melting method. However, this document does not describe any use of the two-fluid spray nozzle in the gas cooling process.

Regarding cooling of gas using a two-fluid spray nozzle, Patent Documents 2 and 3 disclose a method of cooling to a predetermined temperature or less by spraying hot water of 100 ° C. or more and 1 kgf / cm ² or more to exhaust gas. Further, a cooling device is described that uses a two-fluid spray nozzle as a hot water spraying means and sprays air together with hot water.

  However, even in the technique disclosed in the above-mentioned document, air is used as the atomizing gas in the cooling process, and there are other examples in which a process gas such as a combustible gas generated by a gas generator is used. I can't find it.

WO2000 / 045090 (Patent No. 3558039) (Claims and page 9, line 45 to page 15, line 18) JP 2001-314725 A (Claims and paragraphs [0009] to [0014]) JP 2001-324128 A (Claims and paragraphs [0009] to [0017])

  As described above, the following problems remain in the prior art. That is, nitrogen gas or the like used for spray cooling of the product gas is mixed into the product gas after being cooled and becomes a part of the product gas. The function required of the gasification melting furnace device that generates combustible gas is not only to generate combustible gas, but also to purify the generated gas into product gas that can be recycled into fuel, etc. In order to effectively use the product gas, it is preferable that the calorific value (latent heat) of the gas is high and the composition and the calorific value are less varied.

  Therefore, it is not preferable that the ratio of nonflammable gas components such as nitrogen and air contained in the product gas is increased. In addition, for example, a combustible gas such as carbon monoxide or hydrogen can be used instead of nitrogen or the like, but in any case, it is necessary to separately install a gas supply device, resulting in high cost.

  The present invention has been made in view of the above problems, and the problem is to reduce the amount of nitrogen gas used in either or both of the product gas cooling step and the product gas cleaning step, The object is to produce a high-quality combustible gas having a high calorific value and little fluctuation in the component composition and calorific value.

  In order to solve the above-mentioned problems, the inventors of the present invention have reduced the amount of inert gas such as nitrogen gas used in the product gas cooling step and / or the product gas cleaning step to reduce the component composition and the calorific value. A method for producing a high-quality combustible gas with little fluctuation was studied, the following knowledge was obtained, and the present invention was completed.

  That is, as a gas for spraying the cooling liquid from the two-fluid spray nozzle in the product gas cooling step and / or as a backwashing gas for the bag filter in the gas cleaning step, the product gas cleaned in place of nitrogen gas By using this, it is possible to obtain a high-quality combustible gas that has a high calorific value and little fluctuation in the component composition and calorific value.

  The present invention has been completed based on the above findings, and the gist of the present invention is the gasification and melting method for combustible materials shown in the following (1) to (3) and the gas for combustible materials shown in (4). It is in the chemical melting apparatus.

  (1) In a gasification melting method in which at least one of combustion, melting, or gasification is performed on a combustible material, the product gas generated by the gasification melting treatment is cooled using the purified product gas. A method for gasifying and melting a combustible material, wherein the product gas generated by the gasification and melting treatment is cooled by spraying a liquid for use.

  (2) In a gasification melting method in which at least one of combustion, melting or gasification is performed on a combustible material, a bag filter for removing dust in the generated gas generated by the gasification melting processing is cleaned. A method for gasifying and melting a combustible material, characterized by backwashing using a product gas subjected to a chemical treatment.

  (3) In a gasification and melting method in which at least one of combustion, melting and gasification is performed on a combustible material, one or both of the following (a) and (b) are performed: Gasification and melting method for combustible materials.

(A) The operation of cooling the generated gas generated by the gasification and melting process by spraying the cooling liquid onto the generated gas generated by the gasification and melting process by using the purified product gas (b) Backwashing the bag filter for removing dust in the product gas generated by the gasification and melting treatment with the product gas that has been purified (4) Combustion, melting or gasification of combustible materials A gasification melting apparatus for gasifying and melting a combustible material by performing at least one processing, a gasification melting furnace for performing at least one processing of combustion, melting or gasification of the combustible material, A gas cooling device for cooling the generated gas generated from the gasification melting furnace, and a cooling device for cooling the generated gas in the gas cooling device using the purified product gas installed in the gas cooling device. liquid A two-fluid spray nozzle for spraying, a bag filter for removing dust in the cooled product gas, and the bag filter using the product gas installed and cleaned in the bag filter A backwashing device for backwashing, and a product gas recycling pipe for supplying the product gas after cleaning at least cooled and dust-removed to the two-fluid spray nozzle and / or the backwashing device An apparatus for gasifying and melting combustible materials, comprising:

  In the present invention, the term “combustible” means a substance containing a combustible component, and waste, compost, sludge, manure, waste oil, waste acid, waste alkali and other waste including waste alkali, and other combustible materials. Refers to a substance.

  "Backwashing" means an operation to remove clogging by removing dust adhering to the filter cloth by passing clean gas through the bag filter in the direction opposite to the gas flow during normal operation. To do.

  According to the method of the present invention, the purified product gas is used as the gas for cooling liquid spray supplied to the two-fluid spray nozzle for cooling the product gas and / or the backwash gas for the bag filter. Compared with the case where nitrogen gas is used as the gas, a high-quality combustible gas that reduces the nitrogen content in the product gas as a product, has a high calorific value, and has little fluctuation in component composition and calorific value. Can be manufactured.

Further, the apparatus of the present invention reduces the nitrogen gas consumption of the gasification and melting apparatus as a whole compared to the case of using nitrogen gas as the liquid spray for the two-fluid spray nozzle and / or the backwash gas for the bag filter. Therefore, the scale of the nitrogen gas generation facility can be reduced. Furthermore, compared with the case where a combustible gas such as CO or H ₂ is used as the gas, the scale of the gas generating facilities can be greatly reduced or omitted. Therefore, facility construction costs and maintenance costs can be greatly reduced.

  As described above, the method of the present invention is the gasification and melting method, wherein “the gasification is performed by spraying a cooling liquid onto the product gas generated by the gasification and melting treatment using the purified product gas. Either “the operation of cooling the product gas generated by the melting process” or “the operation of back-washing the bag filter for removing dust in the product gas using the purified product gas” Alternatively, the combustible material gasification and melting method is characterized in that both operations are performed. The apparatus of the present invention is an optimum gasification and melting apparatus for carrying out the above gasification and melting method. Hereinafter, the method and apparatus of the present invention will be described in more detail.

(1) Reducing the amount of nitrogen used by reusing the product gas and increasing the generated gas heat generation In the product gas cooling process (gas cooling device) and / or the gas cleaning process (dust removal device), clean instead of nitrogen gas A test was conducted to reuse the generated gas, and its effect was evaluated.

  Gasification and melting instead of nitrogen gas as cooling liquid spraying gas supplied to the two-fluid spray nozzle installed in the quenching and cooling tower which is a gas cooling device and / or backwashing gas of the bag filter which is a dust removal device By using a gas obtained by purifying the combustible gas generated in the furnace, an increase in the nitrogen content in the generated gas is suppressed.

In order to grasp this point quantitatively, the present inventors conducted a test operation using a test facility having a waste treatment capacity of 20 t / d and a generated gas amount of about 800 Nm ³ / h. As a result, when nitrogen gas was used as the gas, the calorific value of the generated gas was 7377 kJ / Nm ³ (1762 kcal / Nm ³ ) on average for 30 minutes, whereas When the purified generated gas was used, the generated gas had a calorific value of 8041 kJ / Nm ³ (1921 kcal / Nm ³ ) on average for 30 minutes, confirming a 9% increase in the calorific value.

  The nitrogen content in the product gas in a practical facility with a waste treatment capacity of 132 t / d is 24%. Based on the rate of increase in the calorific value in the test operation results described above, the nitrogen content is reduced by 8% of the product gas amount. Since it is estimated that the reduction ratio of the necessary nitrogen amount is (8/24) × 100 = 33%, it is estimated that the scale of the nitrogen gas generation facility can be reduced by 33%.

(2) Embodiments of the Invention Embodiments of the present invention will be described in more detail with reference to the drawings. FIG. 1 is a flowchart showing an example of an embodiment according to the present invention.

  A combustible material A such as waste is charged into the gasification melting furnace 1 and is gasified and melted at a high temperature in a furnace maintained at a high temperature of 1000 ° C. or more to generate a combustible product gas B. At this time, the incombustible component becomes molten slag, and is discharged separately from the generated gas from the discharge port provided in the lower part of the gasification melting furnace.

  The generated gas B is a gas that has a high temperature of 1000 ° C. or higher and contains soot and the like. The produced gas B is sent through the gas duct 2 to the gas quenching and cooling tower 3 which is a gas cooling device. In the gas quenching and cooling tower 3, the generated gas B is rapidly increased from 1000 ° C. to 200 ° C. in 2 seconds, for example, so that dioxins and the like are not re-synthesized from the generated gas B generated in the gasification melting furnace 1. The temperature is continuously cooled and reduced.

As the gas quenching and cooling means, for example, using a two-fluid spray nozzle 4 installed in the upper part inside the gas quenching and cooling tower 3, the cooling liquid is made to have a droplet diameter of 100 μm or less. In this way, the gas is rapidly sprayed into the gas quenching / cooling tower, and the gas temperature is rapidly lowered by utilizing the heat of evaporation of the droplets. The two-fluid spray nozzle 4 is supplied with a cooling liquid and a spraying gas to generate fine particles of the cooling droplets. As the cooling liquid, a cooling liquid G such as water is supplied from the product gas cooling liquid storage tank 17, while the purified production gas F in the buffer tank 12 is generated as the spray gas. The gas is recycled through the gas recycling pipe 14 and supplied to the two-fluid spray nozzle 4 through the buffer tank 20 after being pressurized by the pressure increasing device 19. In addition, what is necessary is just to pressurize and use the product gas after the purification process supplied as said gas for gas spraying to pressure comparable as the nitrogen gas used as gas for spraying in the prior art.
The gas F sprayed together with the cooling liquid G by the two-fluid spray nozzle 4 is mixed with the product gas B generated in the gasification melting furnace 1 to become a low-temperature product gas C, and passes through the gas duct 5 to the bag filter 6. Sent. Therefore, in the two-fluid spray nozzle 4, by using the product gas F that has been cleaned without using nitrogen gas, the heat generation amount (latent heat) of the product gas C does not decrease, and the original heat generation amount is maintained. There is an effect that can be done.

  The bag filter 6 has a function of removing dust in the product gas C cooled by the gas quenching / cooling tower 3. Since the bag filter 6 is a mechanism for removing dust in the generated gas by passing the generated gas C through the filter cloth bag 7 formed in a bag shape, the filter cloth bag 7 is clogged with dust as it is used. Progresses. Therefore, in order to eliminate the clogging of the filter cloth bag 7, a backwashing gas pipe for performing a backwashing operation for passing a clean gas from the opposite direction to the gas flow during normal operation and eliminating the clogging. 8 is provided.

  In the present invention, the purified product gas F is used in the backwashing process. The product gas F after the cleaning treatment used for the backwash operation is mixed with the product gas C and sent to the buffer tank 12 via the gas duct 9, the other gas cleaning device 10, and the induction exhaust fan 11. . Therefore, in the backwashing step of the bag filter, the original heat quantity can be maintained without reducing the heat generation amount of the product gas D by using the product gas F after the cleaning process without using nitrogen.

  The other gas cleaning device 10 is a device for removing fine dust and harmful substances that could not be removed by the bag filter 6. For example, various devices such as a desulfurization facility and an electrostatic precipitator are conceivable, but in the case of a gas cleaning device using nitrogen gas, the possibility of substitution with the product gas in the same manner as the gas quenching and cooling tower 3 or the bag filter 6 is possible. In this case, gas purification can be promoted without reducing the heat generation amount of the product gas D.

  The buffer tank 12 uses the product gas as the gas spraying liquid for the two-fluid spray nozzle of the gas quenching and cooling tower and / or the backwashing gas for the valve filter from the purified product gas. 14 has a function of facilitating branching by keeping the gas pressure constant. It is possible to use a header pipe or a valve instead of the buffer tank 12.

  The product gas after the cleaning process is supplied from the buffer tank 12 to the product gas utilization facility 13. As the generated gas utilization equipment, heat utilization or power generation equipment such as a gas engine or a gas-fired boiler is often adopted, but chemical raw material production equipment can also be applied. In this way, the gas after energy recovery as motive power, thermal energy, electric energy, etc. is subjected to a complete combustion treatment as necessary, and is discharged out of the system as exhaust gas E.

  The product gas reuse pipe 14 for recycle supply of the product gas to the gas quenching and cooling tower and / or the valve filter is provided with the booster 19 and the buffer tank 20, and for adjusting the flow rate as necessary. Valves 15 and 16 are provided.

  FIG. 2 is a flow diagram of an embodiment of the prior art. The flow shown in FIG. 1 is the same as that shown in FIG. 1 except that the gas supplied to the two-fluid nozzle 4 and / or the backwash pipe 8 installed in the bag filter 6 is nitrogen gas. This is the same as the case of the figure. That is, in FIG. 1, the purified product gas F is reused, whereas in the conventional example shown in FIG. 2, the nitrogen gas H produced by the nitrogen gas generator 18 is gas. It is supplied to the two-fluid spray nozzle 4 installed in the quenching and cooling tower 3 and / or the backwash pipe 8 installed in the bag filter 6.

  Therefore, as described above, in the prior art, these nitrogen gases are mixed into the purified product gas, the combustible component content in the gas is reduced, the calorific value is reduced, and at the same time, the component composition Fluctuation is large, and it is difficult to supply high-quality gas to the product gas utilization facility 13. Further, the scale of the nitrogen gas generator 18 increases, and the construction cost and the maintenance cost increase.

  According to the method of the present invention, the purified product gas is used as the gas for cooling liquid spray supplied to the two-fluid spray nozzle for cooling the product gas and / or the backwash gas for the bag filter. Compared with the case where nitrogen gas is used as the gas, a high-quality combustible gas that reduces the nitrogen content in the product gas as a product, has a high calorific value, and has little fluctuation in component composition and calorific value. Can be manufactured.

Further, the apparatus of the present invention reduces the nitrogen gas consumption of the gasification and melting apparatus as a whole compared to the case of using nitrogen gas as the liquid spray for the two-fluid spray nozzle and / or the backwash gas for the bag filter. Therefore, the scale of the nitrogen gas generation facility can be reduced. Furthermore, compared to the case where a flammable gas such as CO or H ₂ is used as the gas, the scale of the gas generating facilities can be greatly reduced or omitted, and the facility construction costs and the maintenance costs can be greatly reduced. .

  Therefore, the combustible material gasification and melting method and gasification and melting device of the present invention are technologies of high practical value that can be widely applied in waste treatment, high-quality combustible gas production, and their application fields.

It is a flowchart which shows the example of embodiment which concerns on this invention. It is a flowchart which shows embodiment of a prior art.

Explanation of symbols

1: gasification melting furnace, 2, 5, 9: gas duct,
3: Gas quenching decelerating tower (gas cooling device), 4: Two-fluid spray nozzle,
6: Bag filter (dust remover), 7: Filter cloth bag,
8: Gas piping for backwashing, 10: Other gas cleaning devices,
11: Attracting exhaust fan, 12: Buffer tank (or header or valve),
13: Production gas utilization equipment, 14: Production gas reuse piping,
15: Two-fluid spray nozzle gas flow rate adjustment valve,
16: Gas flow adjustment valve for bag filter backwashing,
17: Liquid storage tank for product gas cooling, 18: Nitrogen gas generator,
19: pressurizer, 20: buffer tank A: combustible, B: product gas (high temperature, containing dust),
C: Product gas (low temperature, containing dust), D: Product gas (low temperature, cleaned),
E: exhaust gas (exhaust gas in which the product gas is completely burned),
F: Product gas (low temperature, cleaned, product gas cooling and / or bag filter backwashing),
G: Liquid for gas cooling, H: Nitrogen gas

Claims (4)

  In a gasification melting method in which at least one of combustion, melting, or gasification is performed on a combustible material, a cooling liquid is used as a generated gas generated by the gasification melting processing, using the purified generated gas. A method for gasifying and melting a combustible material, characterized in that the generated gas generated by the gasification and melting treatment is cooled by spraying.   In a gasification melting method in which at least one of combustion, melting, or gasification is performed on a combustible material, a bag filter for removing dust in a product gas generated by the gasification melting processing is cleaned. A method for gasifying and melting combustible materials, wherein the product gas is back-washed using the generated gas. In a gasification melting method in which at least one of combustion, melting, or gasification is performed on a combustible material, either or both of the following operations (a) and (b) are performed: Gasification melting method.
(A) The operation of cooling the generated gas generated by the gasification and melting process by spraying the cooling liquid onto the generated gas generated by the gasification and melting process by using the purified product gas (b) Operation of back-washing the bag filter for removing dust in the product gas generated by gasification and melting with the product gas that has been cleaned. A gasification and melting apparatus for gasifying and melting a combustible material by performing at least one of combustion, melting or gasification on the combustible material, wherein at least one of combustion, melting or gasification of the combustible material A gasification melting furnace for performing two treatments, a gas cooling device for cooling a product gas generated from the gasification melting furnace, and a purified product gas installed in the gas cooling device A two-fluid spray nozzle for spraying a cooling liquid onto the product gas in the gas cooling device, a bag filter for removing dust in the cooled product gas, and installed in the bag filter, A backwashing device for backwashing the bag filter using the purified product gas, and at least the two-fluid spray nozzle containing the purified product gas after the cooling and dust removing treatment. And / or gasification melting apparatus combustibles, characterized in that it comprises a product gas recycling pipe for supplying the backwash device.

Images