JP2011012875A - Method and device for suppressing generation of hydrogen chloride gas in waste gasification melting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for suppressing generation of hydrogen chloride gas and sulfur oxide gas generated by burning of waste.SOLUTION: In the method and device for suppressing generation of hydrogen chloride gas in a waste gasification melting furnace, linestone fine powder of 1-30 μm is continuously blown into the flame of a combustion burner provided in a combustion chamber and burnt therein in the step of burning generated pyrolysis gas by the combustion burner in the waste gasification melting furnace.

Description

  The present invention relates to a method and apparatus for suppressing the generation of hydrogen chloride gas and sulfur oxide gas generated by combustion of waste.

  Conventionally, in waste gasification and melting furnaces, chlorine and sulfur contained in the waste are transferred to the pyrolysis gas generated from the gasification and melting furnace and combustible dust accompanying the gas. Is contained in dust. In the process of burning this dust with a combustion burner provided in the combustion chamber, sulfur oxide gas (SOx) and hydrogen chloride gas (HCl) harmful to the human body are generated and included in the combustion exhaust gas.

In order to remove the toxic gas, conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2008-23484 (Patent Document 1), the combustion exhaust gas is cooled by a boiler or the like, and then slaked lime is added to the back filter inlet flue. In general, slaked lime adhering to the back filter filter cloth is blown out and reacted with SO _X and HCl in the exhaust gas passing through the filter cloth to be removed from the exhaust gas.

  Further, as disclosed in Japanese Patent Laid-Open No. 2006-297261 (Patent Document 2), in order to simultaneously remove dioxins, NOx, and SOx contained in the exhaust gas, it is disposed on the downstream side of the electron beam irradiation means. A second dust collecting means is provided, a slaked lime supply means is provided in the middle of the gas flow path from the dust collecting means for collecting the soot contained in the exhaust gas to the second dust collecting means, and the second dust collecting means A method of collecting calcium nitrate and calcium sulfate, which is a reaction between sulfuric acid, hydrogen chloride and slaked lime, has been proposed.

Furthermore, as disclosed in JP-A-64-4222 (Patent Document 3), a gas cooling chamber for cooling exhaust gas generated from the incinerator by combustion of the incineration object from the incinerator and a harmful gas removing device In the method of removing hydrogen chloride contained in the exhaust gas when discharged through the exhaust gas exhaust route leading to the dust collector, an absorbent for contact reaction with hydrogen chloride is added at different locations in the exhaust route. There has been proposed a method for removing hydrogen chloride in exhaust gas that is supplied to the stage and improves the hydrogen chloride absorption performance of the absorbent used in the subsequent stage rather than the absorbent used in the previous stage.
JP 2008-23484 A JP 2006-297261 A Japanese Unexamined Patent Publication No. 64-4222

In Patent Document 1 described above, after cooling combustion exhaust gas with a boiler or the like, slaked lime powder is blown into the back filter inlet flue, and slaked lime adhering to the back filter filter cloth passes through the filter cloth with SO _X and HCl. Although it is removed from the exhaust gas by reacting, the HCl gas and SOx gas generated in the combustion chamber are acidic gases, and since HCl gas strongly corrodes metals at high temperatures, the boiler heat transfer tube in the latter stage It is a factor that corrodes. For this reason, the temperature of the heat transfer tube of the boiler is controlled, and the steam temperature is controlled. For this reason, in a system that generates power with a steam turbine, the corrosion problem of the boiler heat transfer tube greatly affects the power generation efficiency.

  Also, in the shaft furnace type melting furnace, limestone is put into the melting furnace together with debris to adjust the basicity of the molten slag. The HCl at the outlet of the room is usually suppressed to 100-150 ppm and SOx is below 10 ppm. However, in order to raise the boiler steam temperature, it is necessary to further improve the corrosive environment. Therefore, in order to obtain a corrosive effect of the boiler, it is necessary to further reduce the HCl and prevent the fluctuation.

  Furthermore, as shown in the cited document 2 or 3, when supplying and discharging slaked lime to the exhaust gas discharge path leading to the dust collector that collects the dust contained in the exhaust gas, hydrogen chloride contained in the exhaust gas is removed. However, the generated HCl and SOx gas is removed at the back filter inlet, and expensive slaked lime powder that is highly reactive with HCl and SOx is used at a low temperature. The actual condition is that slaked lime 2 to 3 times the SOx is required.

In order to eliminate the problems and requests as described above, the inventors have intensively developed and as a result, injected limestone fine powder into the flame of the combustion burner in the process of burning the gas generated in the melting furnace with the combustion burner, HCl and SOx generated by combustion are reacted in a high-temperature flame and captured as salts such as CaCl ₂ and CaSO ₄ . Furthermore, a method for suppressing the generation of hydrogen chloride gas in a waste gasification and melting furnace, in which residual HCl at the combustion chamber outlet is continuously measured with a laser-type HCl meter, and the amount of limestone blown into HCl that varies depending on the waste quality can be controlled, and The device is provided.

The gist of the invention is that
(1) In the process of burning the generated pyrolysis gas in the waste gasification and melting furnace in the combustion burner provided in the combustion chamber, 1-30 μm fine limestone powder is continuously blown into the flame of the combustion burner. A method for suppressing the generation of hydrogen chloride gas in a waste gasification and melting furnace characterized by burning.

(2) In the combustion method as described in (1) above, a method for suppressing the generation of hydrogen chloride gas in a waste gasification and melting furnace, characterized in that the position where the limestone fine powder is blown is a conduit into which pyrolysis gas enters the combustion burner. .
(3) In the combustion method described in (1), a laser light transmission type hydrogen chloride gas analyzer is used for the combustion chamber outlet flue, and the amount of limestone blown in based on the analysis value of the hydrogen chloride gas analyzer. A method for suppressing the generation of hydrogen chloride gas in a waste gasification and melting furnace, characterized by controlling.

  (4) In a waste gasification and melting furnace, a laser light transmission type hydrogen chloride gas meter light emitter is disposed at one end of the combustion chamber outlet, and a laser light transmission type hydrogen chloride gas meter light receiver is disposed at the other end. Laser light having a wavelength in the absorption region of hydrogen chloride gas is emitted, received by a receiver at the other end, the amount of absorption according to the concentration of hydrogen chloride gas is measured, and the amount of limestone cut out according to the concentration of hydrogen chloride gas In a hydrogen chloride gas generation suppressing device in a waste gasification and melting furnace.

  As described below, the low-cost limestone fine powder according to the present invention is continuously blown directly into the flame of the combustion burner and burned, and at the same time, a laser light transmission type hydrogen chloride gas analyzer is used for the combustion chamber outlet flue, By controlling the limestone injection amount based on the analysis value of the hydrogen chloride gas analyzer, the limestone injection amount can be controlled with respect to fluctuating HCl. An object of the present invention is to provide a stable operation method and apparatus by preventing the fluctuation of HCl.

The present invention will be described in detail below with reference to the drawings.
FIG. 1 is an overall schematic view of a waste gasification melting furnace system according to the present invention. As shown in FIG. 1, garbage 11 stored in a garbage bit is introduced into a melting furnace 1 by a garbage crane 10, and pyrolysis gas of garbage is installed in a combustion chamber 3 via a generated gas pipe 2. 8 is sent. On the other hand, the combustion air is sent from the combustion air fan 9 to the combustion burner 8 and mixed and burned in the combustion chamber 3. The combustion gas is recovered by heat in the boiler 4, cooled, further cooled in the water spray type gas cooling tower 5, removed harmful substances such as dust by the back filter 6, and discharged to the atmosphere by the induction blower 7. .

  In this case, noxious gases such as HCl and SOx are generated in the combustion chamber 3, but as a means for removing this, 1-30 μm limestone fine powder is continuously applied in the flame of the combustion burner, particularly in the pipeline entering the combustion burner. By blowing and burning, limestone powder is blown directly from the limestone blowing device, the limestone powder reacts with HCl or SOx, and is removed from the gas by the following formula.

CaCO ₃ → CaO + CO ₂ (pyrolysis)
CaO + H ₂ O → Ca (OH) ₂ (slaked lime)
Ca (OH) ₂ + 2HCl → CaCl ₂ + 2H ₂ O (dehydrochlorination)

  FIG. 2 is a sectional view of a melting furnace which is an embodiment according to the present invention. The melting furnace generated gas is sent to the combustion burner 8 via the generated gas pipe 2 and branched to a plurality of ports 8a. On the other hand, the combustion air is sent from the combustion air fan 9 to the combustion burner 8 and passes through the generated gas port. An air port 8b arranged so as to be sandwiched is formed, and liquid combustion is performed in the combustion chamber. The limestone fine powder is cut out from the lime powder cutting feeder 13 from the lime powder tank 14, is put into the flow path of the generated gas in the burner section, is diffused and distributed by the flow of the generated gas, and is burned in the flame of the combustion burner from the burner gas port 8a. to go into. In this flame, the limestone is thermally decomposed according to the following formula to change into highly reactive quicklime, reacts with HCl and SOx in the combustion chamber, and HCl and SOx at the outlet of the combustion chamber are suppressed.

  The reason for making limestone fine powder is that the reactivity of HCl and SOx is high in the case of conventional slaked lime, but slaked lime is considerably more expensive than limestone because it requires a process of externally decomposing limestone. Since it becomes high, it is not practical. The reason why the limestone fine powder is 1 to 30 μm is that the workability is poor when it is less than 1 μm, and the reactivity between HCl and SOx is poor when it exceeds 30 μm, so the range is set to 1 to 30 μm. Preferably, it is 10 to 25 μm.

  Further, a laser type HCl meter is provided at the outlet of the combustion chamber, and laser light 12 having a wavelength in the absorption region of HCl gas emitted from the light emitter 15a provided at one end of the outlet pipe is emitted and received by the light receiver 15b. Then, the amount of absorption corresponding to the HCl concentration is measured and the HCl concentration is output. In accordance with this HCl concentration, the amount of limestone fine powder cut out is controlled and cut out from the lime powder cutout feeder 13, and the combustion chamber outlet HCl concentration is controlled to be kept at a low value with an appropriate amount of limestone. Furthermore, the limestone fine powder that has been blown is converted into quick lime in a high temperature flame, and unreacted quick lime functions as a substitute for slaked lime in the back filter.

  As described above, low-cost limestone fine powder is directly blown into the flame of a direct combustion burner and burned, and at the same time, using a laser light transmission type hydrogen chloride gas analyzer in the combustion chamber outlet flue, hydrogen chloride gas analysis By controlling the amount of limestone blown based on the analytical value of the meter, the amount of limestone blown can be controlled with respect to fluctuating HCl, thereby preventing corrosion of equipment and the like due to reduction in HCl, and Preventing fluctuations in HCl, enabling stable operation.

It is the whole system schematic diagram of the waste gasification melting furnace concerning the present invention. It is sectional drawing of the melting furnace which is the Example which concerns on this invention.

DESCRIPTION OF SYMBOLS 1 Melting furnace 2 Generating gas pipe 3 Combustion chamber 4 Boiler 5 Water spray type gas cooling tower 6 Back filter 7 Induction fan 8 Combustion burner 8a Port 8b Air port 9 Combustion air fan 10 Garbage crane 11 Garbage 12 Laser light 13 Lime powder cutting Fider 14 Lime powder tank 15a Light emitter 15b Light receiver

Patent Applicant Nippon Steel Engineering Co., Ltd. 1
Attorney Attorney Shiina and others 1

Claims (4)

In the waste gasification and melting furnace, in the process of burning the generated pyrolysis gas with the combustion burner provided in the combustion chamber, 1-30 μm fine limestone powder is continuously blown into the flame of the combustion burner and burned A method for suppressing the generation of hydrogen chloride gas in a waste gasification and melting furnace. 2. The method for suppressing the generation of hydrogen chloride gas in a waste gasification and melting furnace according to claim 1, wherein the limestone fine powder is blown at a position where the pyrolysis gas enters a combustion burner. 2. The combustion method according to claim 1, wherein a laser light transmission type hydrogen chloride gas analyzer is disposed at the outlet of the combustion chamber, and the amount of limestone blown is controlled based on the analysis value of the hydrogen chloride gas analyzer. A method for suppressing generation of hydrogen chloride gas in a waste gasification and melting furnace. In a waste gasification and melting furnace, a laser light transmission type hydrogen chloride gas meter light emitter is disposed at one end of the combustion chamber outlet, and a laser light transmission type hydrogen chloride gas meter light receiver is disposed at the other end. A laser beam having a wavelength in the light absorption region is emitted, received by a light receiver at the other end, the amount of absorption according to the hydrogen chloride gas concentration is measured, and the amount of limestone cut out according to the hydrogen chloride gas concentration is controlled. An apparatus for suppressing the generation of hydrogen chloride gas in a waste gasification melting furnace.

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