JP2005201620A - Refuse gasifying and melting method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To implement self-heat melting of a low calorific value refuse which has not been self-heat molten in the prior art, without fuel such as kerosene, and to reduce the exhaust gas quantity per heating value. <P>SOLUTION: According to this refuse gasifying and melting method, refuse is gasified taking oxygen as a gasifying agent in a fluidized bed type gasifying furnace 6, the obtained heat composition and solid content are burnt and molten in a melting furnace 9, and the exhaust gas in the melting furnace is discharged to the outside through a gas dust. Some of exhaust gas is extracted from the gas dust on the downstream side of the melting furnace 9, the extracted exhaust gas is supplied as circulated exhaust gas to the fluidized bed type gasifying furnace 6 and the melting furnace 9, oxygen for combustion is supplied to the melting furnace 9, and oxygen and the circulated exhaust gas are premixed to be supplied to the gasifying furnace and the melting furnace. The quantity of oxygen supplied to the gasifying furnace is controlled on the basis of the detected temperature of a fluidized bed. Concerning the temperature of the melting furnace, the temperature in the interior or outlet of the furnace in the melting furnace is detected, and the detected temperature is input to control the quantity of circulated exhaust gas supplied to the melting furnace. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a waste gasification and melting method and apparatus, and more particularly to a waste gasification and melting method and apparatus that take into consideration the expansion of the range of treated materials, facility costs, utility savings, improved thermal efficiency, and reduction of smoke treatment costs. .

  The configuration of a conventional garbage gasification and melting apparatus will be described. Air as an oxidant is blown into the fluidized bed of the fluidized bed gasifier, and this air reacts with the dust that has entered the fluidized bed gasifier from the supply chute to generate pyrolysis gas. The temperature of the fluidized bed is maintained at about 600 ° C. by this thermal decomposition reaction heat (partial combustion heat). A fluidized bed gasification furnace (hereinafter referred to as a gasification furnace) is operated at an air ratio of 1 or less, and in the case of ordinary waste, an air ratio of 0.3 to 0.6.

  The air ratio is controlled so that the temperature of the gasification furnace including the fluidized bed is about 900 ° C. or less in order to avoid the problem of ash melt adhesion in the gasification furnace. That is, if the temperature in the fluidized bed and the furnace is too high, the air ratio of the gasification furnace is lowered, and conversely, if the temperature is too low, the air ratio is increased to control the furnace temperature. ing. Alternatively, a case in which the amount of air is kept constant and the amount of dust supplied is controlled for control may be employed. Here, a case where the amount of air supplied to the fluidized bed is controlled based on the temperature of the fluidized bed will be described.

  In many cases, the fluidized bed of a gasifier usually uses sand having a particle size of about 1 mm as an in-layer medium. That is, the fluidized bed is filled with fine sand. On the other hand, coarse incombustible foreign matters are usually mixed in the garbage, and these incombustible foreign matters are deposited at the bottom of the fluidized bed and discharged outside the furnace through piping at the bottom of the gasification furnace.

  The pyrolysis gas and char generated from the garbage in the gasification furnace enter the melting furnace through the flue, react with the air blown into the melting furnace, and burn completely. Most of the ash contained in the char is melted by the high heat of the melting furnace, becomes slag, and is discharged from the bottom of the melting furnace via the slag discharge device.

Since the melting furnace is a high-temperature combustion furnace at 1,300 ° C. or higher, a large amount of thermal NOx is generated if the air ratio is too high. On the other hand, if the air ratio is lowered too much, incomplete combustion occurs. Therefore, the air ratio in the vicinity of 1.0 to 1.05 is controlled as a target as a slightly excessive air ratio. Here, the O ₂ concentration at the melting furnace outlet is measured, and the amount of air supplied to the melting furnace is adjusted based on the measured O ₂ concentration.

  However, there are some plants that prioritize cost reduction by omitting control and adjusting the amount of air to the melting furnace semi-fixed and adjusting with a manual valve when there is little change in waste quality and quantity.

The melting furnace exhaust gas containing some unburned content and NOx enters the boiler, and the unburned content is completely burned by the air blown into the boiler from the piping. The air ratio in this boiler is normally controlled to be about 1.2 to 1.3 in order to cause complete combustion. Exhaust gas from the boiler is discharged from the chimney to the atmosphere via an air heater, a gas quenching tower, a first dust collector, a second dust collector, and an induction fan. The air ratio in the boiler is usually controlled by measuring the O ₂ concentration at the outlet of the _second dust collector and changing the amount of air supplied to the boiler based on the measured O ₂ concentration.

  In the case of garbage with a high moisture content and a low calorific value, the flame temperature is low and does not reach the melting temperature of garbage ash (about 1350 ° C.), so the ash cannot be melted by the combustion heat of the garbage alone. That is, self-heating cannot be performed.

  For example, FIG. 2 shows the results of calculating the flame temperature for wastes with moisture of 50%, 60%, and 70%. For garbage with a moisture content of 50%, the general ash melting temperature exceeds 1350 ° C in a wide range of air ratios, but with a 60% moisture content, the ash melting temperature exceeds only 1350 ° C in a very narrow air ratio. It is.

  The ash melting temperature is not reached at any air ratio when the waste reaches 70% moisture. That is, in the case of high-moisture low-calorie waste, ash cannot be melted without high-calorie fuel such as expensive kerosene.

  Activated carbon is blown into the flue upstream of the first dust collector to adsorb dioxins. The activated carbon is returned to the melting furnace through piping along with the collected ash of the first dust collector, and the dioxins adsorbed on the activated carbon and the activated carbon are combusted or thermally decomposed by the high heat of the melting furnace.

  Slaked lime is blown into the upstream side flue of the second dust collector to adsorb and remove chlorine in the exhaust gas. The collected ash of the second dust collector is taken out from the bottom of the second dust collector, sent to the ash stabilizer, and stabilized by a chemical or the like, and then disposed of in landfill.

There are the following three major problems in this prior art.
1) Self-melting is not possible with low-calorie waste, so it is necessary to supplement expensive external fuel.
2) Since 40 to 60% of moisture is contained in the waste, the amount of exhaust gas per unit calorie is large and the sensible heat loss of exhaust gas is large compared to natural gas, oil or coal fired boilers. That is, the thermal efficiency is low.
3) Since the amount of exhaust gas is large, a large capacity exhaust gas treatment facility is required.

  In Patent Document 1, a part of the pyrolysis gas discharged from the gasification furnace is circulated and supplied as a fluidizing gas of a fluidized bed gasifier, and oxygen is supplied together with the pyrolysis gas or separately from the pyrolysis gas. It is described that it is supplied to a gasifier.

  In Patent Document 2, when fluid is pyrolyzed and gasified while fluidizing with a fluidized medium in a fluidized bed pyrolysis furnace and the resulting pyrolysis gas is burned in a boiler to heat the steam, the combustion gas is introduced from the middle of the boiler. Is extracted, mixed with fluidized air, and introduced into a pyrolysis furnace.

  Patent Document 3 discloses a gasification furnace that partially oxidizes and burns garbage at a low air ratio, a melting furnace that burns and melts unburned components and solids (char) generated in the gasification furnace, and unburned from the melting furnace. In a waste gasification and melting facility equipped with a secondary combustion chamber for completely burning the components and an exhaust gas treatment facility for treating exhaust gas from the secondary combustion chamber, the melting furnace has a reducing atmosphere (less than the theoretical air ratio), An example is shown in which the combustion exhaust gas treated as exhaust gas as a complete combustion gas is supplied to the secondary combustion chamber in multiple stages.

  In Patent Document 4, in a method of gasifying waste at a low temperature in a fluidized bed gasification furnace and introducing the resulting gas and char into a melting furnace and gasifying at a high temperature, It is described that the input gas for air is selected from air, oxygen-enriched air, oxygen and steam, and the input gas for gasification in the melting furnace is selected from oxygen-enriched air or oxygen Has been.

  In recent years, gasification and melting furnace systems that melt and detoxify ash using the combustion heat of garbage itself are being put into practical use (for example, see Non-Patent Document 1).

  In addition to this, exhaust gas circulation oxygen combustion technology has been studied for the purpose of suppressing global warming gas. For example, Non-Patent Document 2, Non-Patent Document 3, and Non-Patent Document 4 and Non-Patent Document 5 are disclosed as examples of fluidized bed combustion applied to pulverized coal combustion.

All of these conventional techniques have been studied for the purpose of facilitating absorption and fixation of CO _{2 in} the flue gas by increasing the CO ₂ concentration in the flue gas as much as possible.

JP 2000-18531 A Japanese Patent Laid-Open No. 11-173520 Japanese Patent Laid-Open No. 2002-31212 JP-A-10-128288 Oyatsu et al .: Development of waste gasification and melting system, Proceedings of the 11th Annual Conference of Japan Society of Waste Management, (2000-11) Hirama et al .: Nitrogen oxide generation characteristics and coal type dependence in CO2 / O2 fluidized bed coal combustion, 3rd Fluidized Bed Symposium, (1997-12) Bonn B. and Baumann H .; Coal Science, Elsevier, p. 1257, (1995) Nakayama S., Miyamae S., Maeda U. and Tanaka T.; J. Japan Soc. Of Energy and Resources (ENERUGI SIGEN), vol.14, 78 (1993) Okazaki K. and Ando T.; Energy, vol. 22, 207 (1997)

The prior art has the following problems.
(1) Low-calorie waste cannot be self-heated and requires external fuel such as kerosene.
(2) Compared with gas fired oil, oil fired, and coal fired boilers, the amount of exhaust gas per calorie is large and the sensible heat loss of exhaust gas is large, so the thermal efficiency is low.
(3) The amount of exhaust gas per calorie is large and the exhaust gas treatment equipment is large.

  The techniques described in Patent Documents 1 to 4 do not solve the above problem. In addition, the techniques described in Non-Patent Documents 1 to 5 do not solve the above problem.

  An object of the present invention is to enable low-temperature calorie waste, which cannot be self-heated by the prior art, to be self-heated without using external fuel such as kerosene, and to reduce the amount of exhaust gas per calorie and to obtain high thermal efficiency. There is.

The present invention solves the above problems by gasifying garbage in a fluidized bed gasifier using oxygen as a gasifying agent, burning and melting the resulting pyrolysis gas and solids in a melting furnace, and A waste gasification melting method for discharging to the outside through a road, wherein a part of the exhaust gas is extracted from the flue downstream of the melting furnace, and the extracted exhaust gas is used as a circulating exhaust gas to the fluidized bed gasification furnace and the melting furnace. This is achieved by a waste gasification and melting method including a procedure for supplying oxygen for combustion to the melting furnace.
(1) Nitrogen contained in the air is inactive and plays only the role of a diluent in gasification and combustion, and is a causative substance that lowers the furnace temperature. By using oxygen as a gasifying agent, high-temperature combustion of high-moisture waste and low-calorie waste whose water content exceeds 70 percent is facilitated.
(2) The amount of exhaust gas is small because the gasification agent does not contain nitrogen, and exhaust gas treatment equipment such as dust collectors, denitration equipment, and chimneys can be made compact and low-cost, while reducing sensible heat loss of exhaust gas. Therefore, high thermal efficiency can be realized as a plant.
(3) For the problem that the temperature of the gasification furnace and the melting furnace is excessively increased by using oxygen, the temperature is obtained by recirculating the melting furnace exhaust gas mainly composed of CO ₂ and H ₂ O. Can be controlled.

  In the waste gasification and melting method, it is desirable that oxygen and the circulating exhaust gas are mixed in advance and then supplied to a fluidized bed gasification furnace and a melting furnace.

  In addition, the amount of circulating exhaust gas supplied to the fluidized bed gasifier is set so that the gas flow rate in the fluidized bed is equal to or higher than the flow start speed of the in-bed medium and less than the scattering speed of the in-bed medium with only the circulating exhaust gas. The amount of oxygen supplied to the fluidized bed gasifier is detected when the fluidized bed temperature is detected, and is decreased when the detected fluidized bed temperature is higher than a preset temperature. It is desirable that the temperature is controlled to increase when the temperature is lower than the set temperature.

  Further, regarding the temperature control of the melting furnace, the temperature of the melting furnace is controlled by detecting the temperature inside the furnace or at the outlet of the melting furnace and controlling the amount of exhaust gas supplied to the melting furnace using the detected temperature as an input. It is desirable.

  When starting up a waste gasifier to which the above-mentioned waste gasification and melting method is applied, start up while supplying air sucked from the atmosphere as an oxidant for combustion of the starter of the fluidized bed gasification furnace and melting furnace. It is desirable to ignite the burner.

  The above problems also include a fluidized bed type gasification furnace that thermally decomposes and gasifies garbage, a melting furnace that burns and melts the pyrolysis gas and solid content obtained in the fluidized bed type gasification furnace, and this melting A flue that leads to the exhaust gas discharged from the furnace, an exhaust gas extraction pipe that branches off from the flue, and a suction side connected to the exhaust gas extraction pipe are provided to extract a part of the flue gas exhaust. A gas is supplied to the fluidized bed gasifier through a circulating blower that pressurizes and feeds it as a circulating exhaust gas, and a gasifier oxygen control valve that is connected to the fluidized bed gasifier and can control the opening degree. Pressurized by the oxygen generator supply pipe, the melting furnace oxygen supply pipe connected to the melting furnace and supplying oxygen to the melting furnace via a melting furnace oxygen control valve whose opening degree can be controlled, and the circulating blower Gasifier circulation that can control the opening of part of the circulating exhaust gas A gasification furnace exhaust gas supply pipe for supplying gasification furnace to the gasification furnace via a gas control valve, and a melting furnace circulation exhaust gas control valve capable of controlling the opening degree of the other part of the circulation exhaust gas pressurized by the circulation fan. A melting furnace circulating exhaust gas supply pipe for supplying to the melting furnace, a fluidized bed thermometer for detecting and outputting a fluidized bed temperature of the fluidized bed gasifier, and an output of the fluidized bed thermometer as an input to the gas Gasifier oxygen control means for controlling the opening degree of the furnace oxygen control valve, a melting furnace thermometer for detecting and outputting the temperature of the melting furnace, and the melting furnace circulating exhaust gas with the output of the melting furnace thermometer as input Melting furnace circulating exhaust gas control means for controlling the opening degree of the control valve, an oxygen concentration meter for detecting and outputting the oxygen concentration of the exhaust gas in the flue on the melting furnace exit side, and the melting using the output of the oxygen concentration meter as input Melting to control the opening of the furnace oxygen control valve An oxygen control means, and the gasifier oxygen supply pipe and the gasifier circulation exhaust gas supply pipe are respectively provided downstream of the gasifier oxygen control valve and the gasifier circulation exhaust gas supply pipe. Waste gas that is joined to each other on the downstream side of the valve and connected to the fluidized bed gasifier with the same piping, and oxygen and the circulating exhaust gas are mixed and flow into the fluidized bed gasifier This can also be achieved by a chemical melting apparatus.

  The gasification furnace oxygen control means reduces the amount of oxygen supplied to the gasification furnace when the fluidized bed temperature is higher than the predetermined temperature range, and reduces the gas amount when the fluidized bed temperature is lower than the predetermined temperature range. The opening degree of the gasifier oxygen control valve is controlled so as to increase the amount of oxygen supplied to the chemical furnace, and the melting furnace circulation exhaust gas control means is, when the temperature of the melting furnace is higher than a predetermined temperature range, When the amount of circulating exhaust gas supplied to the melting furnace is increased and the temperature of the melting furnace is lower than the predetermined temperature range, the opening degree of the melting furnace circulating exhaust gas control valve is set to reduce the amount of circulating exhaust gas supplied to the melting furnace. If the oxygen concentration in the flue gas in the melting furnace outlet flue is higher than the predetermined concentration range, the melting furnace oxygen control means reduces the amount of oxygen supplied to the melting furnace and sets the predetermined concentration range. If it is lower than To increase the amount of oxygen supply, so as to control the opening of the melting furnace oxygen control valve, it is desirable to configure each.

  Also, the melting furnace oxygen supply pipe and the melting furnace circulation exhaust gas supply pipe are merged with each other on the downstream side of the melting furnace oxygen control valve and the downstream side of the melting furnace circulation exhaust gas control valve, respectively. It is desirable to connect the furnace so that oxygen and the circulating exhaust gas are mixed and flow into the melting furnace.

  Further, an air suction pipe branched to the suction side pipe of the circulation fan and connected to the atmosphere is connected, and a discharge side pipe of the circulation fan is connected to the combustion air pipe of the gasification furnace start burner and the combustion of the melting furnace start burner. It is desirable to be connected to each air piping. In addition to the circulation blower, a blower whose suction side communicates with the atmosphere may be provided, and the discharge side of this blower may be connected to the combustion air piping of the gasification furnace starting burner and the combustion air piping of the melting furnace starting burner.

  When starting up a fluidized bed gasification furnace or melting furnace, the atmosphere is sucked and supplied to each startup burner to ignite the startup burner. This prevents the burner from being misfired due to the lack of oxygen when the start burner is ignited.

The effects of the present invention are as follows.
1) Expansion of the range of processed materials for gasification and melting systems. Conventionally, low-calorie waste such as high-moisture sewage sludge and high-ash landfill waste, which have been difficult to self-melt, can be self-heated and processing costs can be reduced.
2) The amount of CO ₂ generated during processing can be reduced by the amount that does not require auxiliary combustion.
3) The amount of exhaust gas is small, making it possible to reduce the size and cost of the flue gas treatment facility. The capacity of gas quenching towers, bag filters, denitration equipment, chimneys, etc. can be halved.
4) Since sensible heat loss of exhaust gas can be reduced, it helps to improve the thermal efficiency of the plant.

(Example 1)
A first embodiment of the present invention is shown in FIG. The illustrated garbage gasification melting system includes a fluidized bed type gasification furnace (hereinafter referred to as a gasification furnace) 6 provided with a supply chute 5, a melting furnace 9 connected to the gasification furnace 6 through a flue 12a, A boiler 3 connected to the furnace 9 via a flue 12b; an air heater 14 connected to the boiler 3 via a flue 12c and having an oxygen flow path; a gas quenching tower 13 connected to the air heater 14 via a flue 12d; A dust collector 15 connected to the quenching tower 13 by a flue 12e, a dust collector 10 connected to the dust collector 15 by a flue 12f, and a flue 12g having a damper 18 attached to the dust collector 10 The connected induction fan 16, the chimney 17 connected to the outlet side of the induction fan 16 by a flue 12h, the slag discharger 11 connected to the bottom of the melting furnace 9, and the ash connected to the bottom of the dust collector 10 Stabilizer 25, boiler 3, gas quenching tower 1 And a gas collection ash recirculation system in which each bottom of the dust collector 15 is connected to the melting furnace 9, an oxygen supply system for supplying oxygen to the gasification furnace 6, the melting furnace 9 and the boiler 3, and exhaust gas from the boiler 3 And an exhaust gas recirculation system for recirculating the gas to the gasification furnace 6, the melting furnace 9, and the boiler 3.

  A pipe 40 for introducing activated carbon is connected to the flue 12e, and a pipe 41 for introducing slaked lime is connected to the flue 12f.

  The gas collection ash recirculation system includes a pipe 23 that connects the bottom of the dust collector 15 to the melting furnace 9, a pipe 24 a that connects the bottom of the gas quench tower 13 to the pipe 23, and a pipe 23 that connects the bottom of the boiler 3. The pipe 24b to be connected is included.

The oxygen supply system includes an oxygen generator 1, a blower 19 connected to the oxygen generator 1 by a pipe 49 on the suction side, and a pipe connecting an outlet of the blower 19 and an inlet side of an oxygen flow path built in the air heater 14. 50, a piping 21 a that connects the outlet side of the oxygen flow path built in the air heater 14 to the inlet side of the gasifier oxygen control valve (hereinafter referred to as a control valve 33) capable of opening control, and the outlet of the control valve 33 21b connecting the gasification furnace 6 to the side, the pipe 4 and the pipe 20 branched from the pipe 21a, and the boiler connected to the boiler 3 by the pipe 46 at the inlet side and connected at the outlet side An oxygen control valve (hereinafter referred to as a control valve 39) and a melting furnace oxygen control valve (hereinafter referred to as a control valve 45) having an opening control that is connected to the piping 20 and connected to the melting furnace 9 via a piping 43 on the outlet side. And the oxygen concentration in the flue 12 g Oximeter detects (hereinafter, O of ₂ meter 37) and, O ₂ meter 37 Boiler oxygen control means for controlling the opening degree of the control valve 39 as an input the output (hereinafter, referred to as controller 38) and the smoke An oxygen concentration meter (hereinafter referred to as an O ₂ meter 34) that detects the oxygen concentration of the road 12b, and a melting furnace oxygen control means (hereinafter referred to as a controller) that controls the opening degree of the control valve 45 with the output of the O ₂ meter 34 as an input. 44), a fluidized bed thermometer (hereinafter referred to as a thermometer 31) for detecting the temperature of the fluidized bed 8 of the gasification furnace 6, and a gas for controlling the opening degree of the control valve 33 using the output of the thermometer 31 as an input. It comprises a furnace oxygen control means (hereinafter referred to as controller 32).

  In the following description, oxygen means a gas that can be used industrially or commercially as oxygen, and does not include oxygen in a state of being contained in air.

  The exhaust gas recirculation system includes an exhaust gas extraction pipe (hereinafter referred to as a pipe 26) that is branched from the flue 12c, a circulation fan 30 that is connected to the pipe 26, and an outlet of the circulation fan 30. A pipe 27 that connects the pipe 21b to the side, a pipe 29 that communicates the pipe 27 and the pipe 46 via a control valve 47 that can control the opening, and a melting furnace that can control the opening of the pipe 27 and the pipe 43 A pipe 28 communicating via a circulating exhaust gas control valve (hereinafter referred to as a control valve 36), and a gasifier capable of controlling the opening degree, which is interposed in the pipe 27 at a position immediately before the pipe 27 is connected to the pipe 21b. A circulating exhaust gas control valve (hereinafter referred to as a control valve 48), a melting furnace thermometer (hereinafter referred to as a thermometer 42) for detecting the temperature of the melting furnace 9, and the output of the thermometer 42 are input to open the control valve 36. Melting furnace circulation to control the degree Gas control unit (hereinafter, referred to as controller 35) is configured to include a.

  The pipes 21a and 21b are gasifier oxygen supply pipes, and the pipes 20 and 43 are melting furnace oxygen supply pipes. Further, the pipes 27 and 21b are gasification furnace circulation exhaust gas supply pipes, and the pipes 28 and 43 are melting furnace circulation exhaust gas supply pipes. Therefore, the gasification furnace oxygen supply pipe and the gasification furnace circulating exhaust gas supply pipe are joined together on the downstream side of the control valve 33 and the downstream side of the control valve 48, respectively. The oxygen and the circulating exhaust gas pass through the same pipe 21b. Are mixed and flow into the gasifier 6. Similarly, the melting furnace oxygen supply pipe and the melting furnace circulating exhaust gas supply pipe are joined together on the downstream side of the control valve 45 and the downstream side of the control valve 36, respectively. The oxygen and the circulating exhaust gas pass through the same pipe 43. It is mixed and flows into the melting furnace 9.

  The oxygen supplied from the oxygen generator 1 is boosted by the blower 19 and then preheated with the exhaust gas introduced from the boiler 3 while passing through the oxygen flow path built in the air heater 14. The piping 21 a, the control valve 33, and the piping The gas is supplied to the gasification furnace 6 through the pipe 21a, to the melting furnace 9 through the pipe 21a, pipe 20, control valve 45 and pipe 43, and to the boiler 3 through the pipe 21a, pipe 4, control valve 39 and pipe 46, respectively.

  In many cases, when only oxygen is blown, the furnace temperatures of the gasification furnace 6 and the melting furnace 9 become excessively high locally, so that the exhaust gas from the outlet of the boiler 3 is passed through the pipe 26 using the circulation fan 30. As suction and circulation exhaust gas, the piping 27, the control valve 48, the piping 21b to the gasification furnace 6, the piping 27, the piping 28, the control valve 36, the piping 43 to the melting furnace 9, the piping 27, the piping 29, the control valve 47, Each is supplied to the boiler 3 through the pipe 46. That is, the oxygen supplied to the gasification furnace 6 is mixed with the circulating exhaust gas flowing in from the pipe 27 in the pipe 21b, then supplied to the gasification furnace 6, and the oxygen supplied to the melting furnace 9 is supplied to the pipe 43. Then, the oxygen is supplied to the melting furnace 9 after being mixed with the circulating exhaust gas flowing in from the pipe 28, and the oxygen supplied to the boiler 3 is mixed with the circulating exhaust gas flowing in from the pipe 29 in the pipe 46. Supplied to.

  Circulating exhaust gas can be blown into the gasification furnace 6, the melting furnace 9, and the boiler 3 separately from oxygen. However, in Example 1, oxygen and circulating exhaust gas are mixed in advance in consideration of the effect of improving mixing, such as prevention of occurrence of a local high temperature portion in the vicinity of the oxygen blowing nozzle, and improvement of the jet flow through the furnace due to an increase in mass flow. The method of blowing into each furnace and boiler was adopted. In the fluidized bed of the gasification furnace 6, a high temperature portion is generated in the vicinity of the high concentration oxygen blowing nozzle and a clinker trouble is likely to occur. Therefore, it is necessary to blow oxygen and circulating exhaust gas into the fluidized bed in a premixed state without fail.

  The temperature of the fluidized bed 8 of the gasification furnace 6 is maintained at about 600 ° C. by the reaction heat (partial combustion heat) of this (oxygen + circulated exhaust gas) mixture and waste. The gasification furnace 6 is operated at an air ratio of 1 or less, and in the case of ordinary waste, an air ratio of 0.3 to 0.6.

  In order to avoid the problem of ash melting and sticking in the gasification furnace 6, the air ratio is controlled so that the temperature of the gasification furnace 6 including the fluidized bed is about 900 ° C. or less.

  In normal gasification, if the furnace temperature becomes too high, the air ratio of the gasification furnace 6 is lowered by reducing the air amount or increasing the amount of dust, and conversely if the temperature is too low. The furnace temperature is controlled by increasing the air ratio by increasing the amount of air or decreasing the amount of dust. However, in the case of fluidized-bed gasification, the amount of change in the air amount is limited in that the fluidized bed is stably fluidized, and the air ratio cannot be changed extremely. That is, if the air amount is lowered too much, clinker troubles due to poor fluidization occur, and conversely if the air amount is too large, the gas flow rate in the furnace becomes excessive and the in-layer medium and unreacted dust will be scattered outside the furnace. This causes a failure.

  On the other hand, in the case of gasification by a mixture of (oxygen + circulated exhaust gas) as in this embodiment, the air ratio can be controlled by controlling the oxygen concentration in addition to increasing / decreasing the flow rate. In the example shown in FIG. 1, stable fluidization of the fluidized bed 8 containing dust is realized only with the circulating exhaust gas supplied from the pipe 27, and the air ratio is controlled by oxygen supplied from the pipe 21 a via the control valve 33. It depends only on the increase and decrease.

  In other words, the amount of circulating exhaust gas from the pipe 27 is fixed at the minimum necessary amount that can maintain stable fluidization, and is not controlled. When the temperature detected by the thermometer 31 is higher than a preset temperature range, the controller 32 reduces the amount of oxygen supplied to the gasification furnace 6 and the temperature detected by the thermometer 31 is preset. When the temperature is lower than the above temperature range, the opening degree of the control valve 33 is controlled so that the amount of oxygen supplied to the gasification furnace 6 is increased. Specifically, when the temperature of the fluidized bed 8 falls below a lower limit temperature (for example, 500 ° C.), the amount of oxygen from the pipe 21b is increased via the controller 32 and the control valve 33 to promote combustion. Increase fluidized bed temperature. Conversely, when the temperature of the fluidized bed 8 approaches the upper limit temperature (for example, 800 ° C.), the amount of oxygen is decreased, the combustion reaction is suppressed, and the fluidized bed temperature is lowered. In this way, the temperature of the fluidized bed is controlled within an appropriate range (for example, 500 ° C. to 800 ° C.).

  As described above, the air ratio control of the gasification furnace 6 is based on the adjustment of the amount of oxygen supplied as a gasifying agent from the pipe 21a via the controller 32 and the control valve 33 based on the output of the thermometer 31. . In this way, it is possible to independently execute the maintenance of the fluidized state and the response to the change in the air ratio. Of course, oxygen and circulating exhaust gas are supplied in a mixed state from below the fluidized bed, and oxygen also has a fluidizing action.

  The pyrolysis gas and char generated in the gasification furnace 6 enter the melting furnace 9 through the flue 12a, react with the air-fuel mixture (oxygen + circulated exhaust gas) blown into the melting furnace 9 through the pipe 43, and burn.

In the melting furnace 9, the amount of oxygen sent from the pipe 20 to the pipe 43 is controlled via the control valve 45 by the controller 44 that receives the output of the O ₂ meter 34 that detects the oxygen concentration in the flue 12 b. The air ratio of the melting furnace 9 is kept at 1.0 to 1.05. When the oxygen concentration detected by the O ₂ meter 34 is higher than a preset concentration range, the controller 44 reduces the amount of oxygen supplied to the melting furnace 9 so that the oxygen concentration detected by the O ₂ meter 34 is reduced. When the concentration is lower than the preset concentration range, the opening degree of the control valve 45 is controlled so that the amount of oxygen supplied to the melting furnace 9 is increased. The circulating exhaust gas fed into the pipe 43 through the pipe 28 and the control valve 36, mixed with oxygen in the pipe 43 and blown into the melting furnace 9 is merely a diluent, and its purpose is temperature adjustment of the melting furnace 9. That is, when the temperature of the melting furnace 9 becomes too high, the controller 35 that receives the output of the thermometer 42 increases the circulated exhaust gas amount fed to the pipe 43 via the control valve 36 and performs tempering. If the temperature of the melting furnace 9 is lowered and the temperature is lowered too much, the amount of the circulating exhaust gas sent to the pipe 43 is reduced to raise the temperature of the melting furnace 9.

When there is no large change in the amount of waste and the quality of waste, the amount of oxygen required in the melting furnace 9 is almost constant. Therefore, the O ₂ meter at the outlet of the melting furnace 9 shown in FIG. 1, the controller 44, the control valve 45 can be omitted, and the amount of oxygen from the pipe 20 can be reduced by operating with a manual valve substantially fixed.

  Most of the ash contained in the char is melted by the high heat of the melting furnace 9 and becomes slag and is discharged via the slag discharge device 11.

The unburned portion slightly contained in the exhaust gas of the melting furnace 9 is completely burned in the boiler 3 by the (oxygen + circulated exhaust gas) mixture blown from the pipe 46. In this boiler 3, the controller 38 that receives the output of the O ₂ meter 37 at the outlet of the dust collector 10 adjusts the amount of oxygen from the pipe 4 through the control valve 39, thereby setting the air ratio to 1. It is controlled to about 2 to 1.3.

  The exhaust gas completely burned in the boiler 3 is purified through the air heater 14, the gas quench tower 13, the dust collector 15, and the dust collector 10, and is discharged from the chimney 17 to the atmosphere.

  Activated carbon is blown into the upstream of the dust collector 15 through the pipe 40 in order to adsorb dioxins. The activated carbon is returned together with the collected ash from the bottom of the dust collector 15 to the melting furnace 9 through the pipe 23, and the activated carbon and the dioxins adsorbed on the activated carbon are combusted or thermally decomposed by the high heat of the melting furnace 9.

  Upstream of the dust collector 10, slaked lime is blown through the pipe 41 to adsorb and remove chlorine in the exhaust gas. The collected ash containing the slaked lime of the dust collector 10 is sent to the ash stabilization device 25, where it is landfilled after being stabilized with a chemical or the like.

The results of applying the waste gasification and melting system shown in FIG. 1 to wastes having a moisture content of 70%, 60% and 50% are shown in FIGS. 3 to 5 and Tables 1 to 3.
(When moisture is 50%)
As shown in FIG. 2 above, if the standard waste has a moisture of 50%, the melting temperature of 1350 ° C. or higher can be maintained even when using normal air. When this example was applied to this 50% moisture waste and the amount of circulating exhaust gas was controlled so that the oxygen concentration in the mixture (total oxygen amount + circulating exhaust gas total amount) was 25%, the flame temperature was calculated. As shown in FIG. 3, the melting temperature was sufficiently maintained. Table 1 shows the results of calculating the amount of exhaust gas from the boiler outlet, the air heater to the smoke outlet, and the amount of circulating exhaust gas per 1 kg of garbage at this time in comparison with the prior art.

エアヒータ〜煙突出口の排ガス量は、従来技術の場合を１００％とすると３９％に低下し大幅に低減できている。これに伴い、ごみ燃焼熱を基準とした排ガスの顕熱損失も従来技術の１１.６％に対し５.１％に低減できた。
（水分６０％の場合）
図２に示したようにごく狭い空気比の範囲でのみ火炎温度を１３５０℃以上に維持できていた水分６０％のごみに本実施例を適用し、（酸素総量＋循環排ガス総量）混合気中の酸素濃度が３０％になるように循環排ガス量を制御した場合について計算した結果、火炎温度は図４に示すように、空気のみの場合よりも広い空気比の範囲で十分に溶融温度を維持できた。

The amount of exhaust gas from the air heater to the smoke outlet is reduced to 39% when the prior art is assumed to be 100%, which is greatly reduced. Along with this, the sensible heat loss of the exhaust gas based on the waste heat of combustion was also reduced to 5.1% compared to 11.6% of the prior art.
(When moisture is 60%)
As shown in FIG. 2, the present example was applied to the waste of 60% moisture whose flame temperature could be maintained at 1350 ° C. or higher only in a very narrow air ratio range, and (total oxygen amount + circulated exhaust gas total amount) As a result of calculation for the case where the amount of circulating exhaust gas is controlled so that the oxygen concentration of the gas becomes 30%, as shown in FIG. 4, the flame temperature is sufficiently maintained within a wider air ratio range than in the case of air alone. did it.

この時、表２に示すように、エアヒータ〜煙突出口の排ガス量は、空気を酸化剤とする従来技術の場合と比較し４３％に低減でき、排ガスの顕熱損失も従来技術の１３.４％に対し６.４％に低減できた。
（水分７０％の場合）
図２に示したようにどのように空気比を調整しても火炎温度が１３５０℃に達せず、灯油などの助燃が不可欠であった水分７０％のごみであっても、本実施例を適用することにより灯油などの助燃無しでガス化溶融できた。すなわち、従来技術であればごみ０.９kgに対し灯油０.１kgを助燃しなければならなかった水分７０％のごみに、本実施例を適用し（酸素総量＋循環排ガス総量）混合気中の酸素濃度が６０％になるように循環排ガス量を制御した場合について計算したところ、助燃無しでも図５に示したように広範囲の空気比で十分に溶融温度１３５０℃を維持できた。

At this time, as shown in Table 2, the amount of exhaust gas from the air heater to the smoke outlet can be reduced to 43% compared to the case of the prior art using air as an oxidizing agent, and the sensible heat loss of the exhaust gas is also 13.4 of the prior art. % Was reduced to 6.4%.
(When moisture is 70%)
As shown in FIG. 2, even if the air ratio is adjusted, the flame temperature does not reach 1350 ° C., and this embodiment is applied even to waste of 70% moisture that was indispensable for auxiliary combustion such as kerosene. By doing so, it was possible to gasify and melt without auxiliary fuel such as kerosene. In other words, in the case of the conventional technology, this example is applied to 70% moisture waste that had to be supplemented with 0.1kg of kerosene to 0.9kg of waste (total amount of oxygen + total amount of circulating exhaust gas). When the amount of circulating exhaust gas was controlled so that the oxygen concentration was 60%, the melting temperature of 1350 ° C. could be sufficiently maintained over a wide range of air ratios as shown in FIG.

この時、表３に示したように、エアヒータ〜煙突出口の排ガス量は従来技術の場合と比較し３１％に減少し、ごみ燃焼熱に対する排ガスの顕熱損失も従来技術の１３.８％から９.１％に減少した。

At this time, as shown in Table 3, the amount of exhaust gas from the air heater to the smoke outlet is reduced to 31% compared to the case of the prior art, and the sensible heat loss of the exhaust gas with respect to the waste combustion heat is also from 13.8% of the prior art. It decreased to 9.1%.

As described above, according to the present embodiment, the amount of exhaust gas can be halved, so that it is possible to greatly reduce the size and cost of the flue gas treatment equipment such as gas quenching tower, dust collector, denitration equipment, and chimney. Furthermore, the thermal efficiency can be improved by reducing the sensible heat loss of the exhaust gas. In addition, high moisture sludge and high ash waste (such as landfill waste) that have been difficult to apply to gasification and melting systems can be melted by self-heating to reduce processing costs and eliminate the need for auxiliary combustion. In addition, the amount of CO ₂ generated during the gasification process is reduced.

Although the present embodiment is a gasification and melting system having a boiler, the present invention can be effectively applied to a small gasification and melting system that does not have a boiler. Further, in a system without a boiler and having a secondary combustion chamber in the melting furnace 9, a mixed gas of oxygen and circulating exhaust gas may be supplied also to the secondary combustion chamber. In this case, an O ₂ meter is provided at the outlet of the secondary combustion chamber, and the air ratio is controlled by adjusting the amount of oxygen using the detected oxygen concentration as an input.

(Example 2)
Next, Embodiment 2 of the present invention will be described with reference to FIG. FIG. 6 shows a main configuration of a waste gasification and melting apparatus according to Embodiment 2 of the present invention. The waste gasification and melting apparatus shown in FIG. 6 is different from the waste gasification and melting apparatus shown in FIG. The startup burner 63 of the gasification furnace 6 and the startup burner 64 of the melting furnace 9 which are not shown in FIG. 1 are described, and the configuration related to the startup burner 63 and the startup burner 64 is shown. . That is, in the basic configuration shown in the first embodiment, a configuration considering the start operation is added.

  In this embodiment, the starter burner 63 of the gasification furnace 6, the oil pipe 65 connected to the starter burner 63 for supplying fuel oil, the oil quantity valve 57 interposed in the oil pipe 65, and the melting furnace 9 The start burner 64, the oil pipe 66 connected to the start burner 64 for supplying fuel oil, the oil amount valve 58 interposed in the oil pipe 66, the pipe 20 and the pipe 43 are connected, and the control valve 45 is connected. A pipe 59 that bypasses the pipe 59, a bypass valve 7 interposed in the pipe 59, a pipe 67 that connects the pipe 27 on the upstream side of the control valve 48 to the pipe 43 on the downstream side of the connection point of the pipe 28, and a pipe 67 The intervening bypass valve 61, the manual valve 62 interposed in the pipe 43 downstream of the connection point of the pipe 67, and the pipe 43 upstream of the manual valve 62 downstream of the connection point of the pipe 67. 68 connected to the start burner 63, and the connection interposed in the pipe 68 A valve 52, a pipe 69 connecting the upstream pipe 68 of the interlock valve 52 to the activation burner 64, an interlock valve 53 interposed in the pipe 69, and a pipe 21 b between the connection points of the control valve 33 and the pipe 27. The point in which the valve 51 interposed is shown in FIG. The oil amount valve 58 and the interlocking valve 53 are interlocked by a link mechanism, and the oil amount valve 57 and the interlocking valve 52 are also interlocked by a link mechanism. Since other configurations are the same as those of the first embodiment, the same reference numerals are given and description thereof is omitted.

The operation of the system in a steady state is as described in the first embodiment. Hereinafter, the starting operation of this embodiment will be described. The starting operation of this embodiment is performed according to the following procedure. 1) Activate necessary equipment such as the induction fan 16, the fan 19, and the circulation fan 30.
2) The valve 51 on the downstream side of the control valve 33 is manually fully closed to prevent excessive oxygen supply to the gasification furnace 6.
3) The control valve 48 interposed in the piping for supplying the circulating exhaust gas to the fluidized bed 8 is set at an opening that can secure a predetermined gas amount, that is, an amount of the circulating exhaust gas necessary for stable fluidization of the fluidized bed.
4) At the time of startup, since low temperature melting furnace 9, thermometer 42, signals the control valve 36 is closed state of the controller 35, also, since all the furnace, the flue is filled with air, O ₂ In response to the O ₂ high signal from the total 34, the control valve 45 is also closed. When both the control valve 36 and the control valve 45 are in the closed state, neither air nor oxygen is supplied to the start burner 63 and the start burner 64. Therefore, a bypass valve 61 is provided in parallel with the control valve 36 in the circulating exhaust gas line. Is manually set to “open”. On the other hand, in the oxygen supply line, a bypass valve 7 is provided in parallel with the control valve 45, and the bypass valve 7 is kept "closed" to prevent excessive inflow of oxygen. The manual valve 62 interposed in the pipe 43 for supplying the (oxygen + circulated exhaust gas) mixture to the melting furnace 9 is closed, and the air other than the starting burner 63 of the gasification furnace 6 and the starting burner 64 of the melting furnace 9 or Prevent oxygen leakage.
5) The start burner 64 of the melting furnace 9 is ignited and the amount of oil supplied to the start burner 64 is gradually increased. An oil quantity valve 58 interposed in an oil pipe 66 for supplying oil to the starting burner 64 and an interlocking valve 53 interposed in a pipe 69 for supplying (oxygen + circulated exhaust gas) mixture to the starting burner 64 are linked mechanisms. As the oil amount increases and decreases, the opening of the interlock valve 53 also increases and decreases, and air corresponding to the oil amount is supplied to the activation burner 64. At the time of start-up, since the entire interior of the furnace and the flue is filled with air, air is sent from the circulation fan 30 to the start burner 64 through the bypass valve 61.
6) Since the oxygen in the system is rapidly consumed after the start burner 64 is ignited, the bypass valve 7 is gradually opened while the oxygen concentration in the system is monitored by the O ₂ meter 34, and the O ₂ concentration at the outlet 9 of the melting furnace 9 (Oxygen concentration in the system) is adjusted to maintain an appropriate value, for example, around 10%.
7) The start burner 63 of the gasification furnace 6 is ignited and the amount of oil supplied to the start burner 63 is gradually increased. An oil amount valve 57 interposed in an oil pipe 65 for supplying oil to the starting burner 63 and an interlocking valve 52 interposed in a pipe for supplying a mixture of (oxygen + circulated exhaust gas) to the starting burner 63 are also linked by a link mechanism. As the oil amount increases or decreases, the opening degree of the interlock valve 52 also increases or decreases, and air corresponding to the oil amount is supplied to the activation burner 63.
8) Also in this case, since oxygen in the system is rapidly consumed after ignition, the bypass valve 7 is gradually opened while monitoring the indicated value of the O ₂ meter 34, and the outlet O ₂ concentration of the melting furnace 9 is Adjust to an appropriate value, for example, around 10%.
9) After confirming that the temperature of the fluidized bed 8 has reached a predetermined temperature (for example, about 500 ° C.), supply of garbage to the gasification furnace 6 through the supply chute 5 is started, and at the same time, the valve 51 and the manual valve 62 are disposed of. The opening is increased as the amount of supply increases.
10) Gradually increase the amount of waste supply, confirm that the fluidized bed temperature of the gasifier 6 has risen and entered the control range of the control valve 33 (for example, 500 to 800 ° C.), and then fix the valve 51 fully open. The oxygen supply to the gasifier 6 is automatically controlled by the control valve 33.
11) The oil quantity valve 57 is closed and the starter burner 63 of the gasifier 6 is extinguished. At the same time, the interlocking valve 52 interlocked with the oil amount valve 57 is also fully closed.
12) Gradually increase the amount of waste supply, combustible gas and char from the gasifier 6 burn in the melting furnace 9, and the indicated value of the O ₂ meter 34 enters the control range (for example, 10% or less), supplying oxygen After confirming that the amount is automatically controlled by the control valve 45, the bypass valve 7 is closed, and the oxygen supply to the melting furnace 9 is automatically controlled.
13) The oil quantity valve 58 is closed and the start burner 64 of the melting furnace 9 is extinguished. At the same time, the interlocking valve 53 interlocked with the oil amount valve 58 is also fully closed.
14) Fully close the bypass valve 61. Thereafter, the amount of circulating exhaust gas through the pipe 28 and the control valve 36 becomes an automatic control mode based on a signal from the thermometer 42.
15) By the above operation, it shifts to the waste-only firing gasification melting mode.

  With the above configuration and operation, when the temperature of the melting furnace 9 is low, it is supplied to the melting furnace 9 according to the controller 35 for reducing the amount of circulating exhaust gas supplied to the melting furnace 9 or the oxygen concentration at the outlet of the melting furnace. The starting operation in the system including the controller 44 for controlling the oxygen amount can be executed.

In the above operation, when the start burner 64 or the start burner 63 is ignited, oxygen in the system is consumed rapidly, and the oxygen concentration in the system is measured with an O ₂ meter 34 in order to prevent the burner from misfiring due to insufficient oxygen. The amount of oxygen supplied to the start burner is increased by operating the manual valve (bypass valve 7) to adjust the oxygen concentration in the system. In this case, if the response of the O ₂ meter 34 is slow, the actual oxygen concentration in the system may be lower than the value indicated by the O ₂ meter 34. In such a situation, there is a concern of a burner misfire due to lack of oxygen.

(Example 3)
Next, Embodiment 3 of the present invention will be described with reference to FIG. In this embodiment, the configuration related to the start operation is added to the basic configuration shown in the first embodiment. The third embodiment differs from the first embodiment in that the starter burner 63 of the gasification furnace 6, the oil pipe 65 connected to the starter burner 63 for supplying fuel oil, and the oil interposed in the oil pipe 65 A quantity valve 57, a start burner 64 of the melting furnace 9, an oil pipe 66 connected to the start burner 64 and supplying fuel oil, and an oil quantity valve 58 interposed in the oil pipe 66 are shown. Further, a combustion air pipe 71 that connects the pipe 27 upstream of the control valve 48 to the start burner 63, an interlocking valve 52 interposed in the combustion air pipe 71, and a combustion air upstream of the interlocking valve 52. Combustion air piping 72 connecting the air piping 71 to the activation burner 64, an interlocking valve 53 interposed in the combustion air piping 72, and a piping 21b between the connection points of the control valve 33 and the piping 27. Valve 51, manual valve 60 interposed in pipe 26, and manual valve 60 below An air suction pipe 2 connected end is opened to the atmosphere branches on the side of the pipe 26, it is that the manual valve 70 interposed in the air suction pipe 2, is provided. The oil amount valve 58 and the interlocking valve 53 are interlocked by a link mechanism, and the oil amount valve 57 and the interlocking valve 52 are also interlocked by a link mechanism. Since other configurations are the same as those of the first embodiment, the same reference numerals are given and description thereof is omitted.

The operation of the system in a steady state is as described in the first embodiment. Hereinafter, the starting operation of this embodiment will be described. The starting operation of this embodiment is performed according to the following procedure. 1) Activate necessary equipment such as the induction blower 16, the blower 19, and the circulation blower 30.
2) The valve 51 is fully closed to prevent excessive oxygen supply to the gasifier 6.
3) Set the control valve 48 to a predetermined opening.
4) Fully close the manual valve 60.
5) Fully open the manual valve 70.
6) The start burner 64 is ignited and the oil amount is gradually increased. The oil amount valve 58 and the interlocking valve 53 are interlocked by a link mechanism, and the opening degree of the interlocking valve 53 increases and decreases with the increase and decrease of the oil amount, and the air corresponding to the oil amount is supplied to the activation burner 64.
7) The start burner 63 is ignited and the oil amount is gradually increased. The oil amount valve 57 and the interlocking valve 52 are also interlocked by a link mechanism, and the opening degree of the interlocking valve 52 increases and decreases as the oil amount increases and decreases, and air corresponding to the oil amount is supplied to the activation burner 63.
8) After confirming that the temperature of the fluidized bed 8 has reached a predetermined temperature (for example, about 500 ° C.), supply of garbage through the supply chute 5 is started.
9) Gradually increase the amount of waste supplied and confirm that combustible gas and char from the gasifier 6 burned in the melting furnace 9 and the indicated value of the O ₂ meter 34 is within the control range (for example, 10% or less). .
10) Confirm that the waste supply amount is gradually increased, the fluidized bed temperature of the gasification furnace 6 has risen, and has entered the control range of the control valve 33 (for example, 500 ° C. to 800 ° C.).
11) Open valve 51 gradually. At this time, the fluidized bed 8 is fluidized by air having an oxygen concentration of 21% supplied through the air suction pipe 2, the circulation blower 30, the pipe 27, the control valve 48, and the pipe 21b. When the valve 51 is gradually opened, oxygen from the pipe 21a is added to this air, the oxygen concentration in the pipe 21b gradually increases, and the temperature of the fluidized bed 8 rises because the combustion reaction becomes active. In response to the rise signal of the layer temperature, the opening degree of the control valve 33 is automatically throttled, and the oxygen concentration in the pipe 21b is controlled within an appropriate range.
12) Gradually reduce the amount of oil in the start burner 63 and extinguish the fire. At this time, the interlocking valve 52 interlocked with the oil amount valve 57 is also fully closed.
13) Slowly extinguish the oil amount of the start burner 64 gradually. At this time, the interlocking valve 53 interlocked with the oil amount valve 58 is also fully closed.
14) Open the manual valve 60 gradually and simultaneously throttle the manual valve 70. Finally, the manual valve 60 is fully opened and the manual valve 70 is fully closed.
15) By the above operation, it shifts to the waste-only firing gasification melting mode.

  As described above, in this embodiment, since the combustion air is supplied to the start burner using the suction atmosphere, the start burner misfire due to lack of oxygen can be completely prevented.

Example 4
Next, Embodiment 4 of the present invention will be described with reference to FIG. In this embodiment, the configuration related to the start operation is added to the basic configuration shown in the first embodiment. The fourth embodiment is different from the third embodiment in that the air suction pipe 2, the manual valve 70 interposed in the air suction pipe 2 and the manual valve 60 interposed in the pipe 26 are not provided. A blower 55 that sucks and pressurizes the air and blows air is provided, and the upstream end of the combustion air pipe is connected to the outlet side of the blower 55 instead of the pipe 27. Since other configurations are the same as those of the third embodiment, the same reference numerals are given and description thereof is omitted.

Also in the present embodiment, the operation in the steady state is as described in the first embodiment. The starting operation is performed according to the following procedure.
1) Start necessary equipment such as the induction fan 16, the fan 19, the circulation fan 30, and the fan 55.
2) The valve 51 is fully closed to prevent excessive oxygen supply to the gasifier 6.
3) Set the control valve 48 to a predetermined opening.
4) The start burner 64 is ignited and the oil amount is gradually increased. The oil amount valve 58 and the interlocking valve 53 are interlocked by a link mechanism, and the opening degree of the interlocking valve 53 increases and decreases with the increase and decrease of the oil amount, and the air corresponding to the oil amount is supplied to the activation burner 64.
5) The start burner 63 is ignited and the oil amount is gradually increased. The oil amount valve 57 and the interlocking valve 52 are also interlocked by a link mechanism, and the opening degree of the interlocking valve 52 increases and decreases as the oil amount increases and decreases, and air corresponding to the oil amount is supplied to the activation burner 63.
6) After confirming that the temperature of the fluidized bed 8 has reached a predetermined temperature (for example, about 500 ° C.), supply of garbage through the supply chute 5 is started.
7) Gradually increase the amount of waste supplied and confirm that combustible gas and char from the gasifier 6 burned in the melting furnace 9 and the indicated value of the O ₂ total 34 has entered the control range (for example, 10% or less). .
8) Confirm that the waste supply amount is gradually increased and the fluidized bed temperature of the gasification furnace 6 has risen and entered the control range of the control valve 33 (for example, 500 ° C. to 800 ° C.).
9) Open valve 51 gradually. At this time, the fluidized bed 8 is fluidized by the circulating exhaust gas supplied through the pipe 26, the circulation fan 30, the pipe 27, the control valve 48, and the pipe 21b. When the valve 51 is gradually opened, oxygen from the pipe 21a is added to this circulating exhaust gas, the oxygen concentration in the pipe 21b gradually increases, and the combustion reaction becomes active, so the temperature of the fluidized bed 8 rises. In response to the rise signal of the layer temperature, the opening degree of the control valve 33 is automatically throttled, and the oxygen concentration in the pipe 21b is controlled to be in an appropriate range.
10) Gradually reduce the amount of oil in the start burner 63 and extinguish the fire. At this time, the interlocking valve 52 interlocked with the oil amount valve 57 is also fully closed.
11) Slowly extinguish the oil amount of the start burner 64 gradually. At this time, the interlocking valve 53 interlocked with the oil amount valve 58 is also fully closed.
12) The blower 55 is stopped.
13) By the above operation, the mode shifts to the garbage-only firing gasification melting mode.

  Also in this embodiment, since the combustion air is supplied to the start burner using the suction atmosphere, the start burner misfire due to lack of oxygen can be completely prevented.

It is a systematic diagram which shows the principal part structure of the gasification melting system which concerns on Example 1 of this invention. It is a graph which shows the calculated value of the flame temperature when burning garbage of various water | moisture contents. It is a graph which shows the calculated value of the flame temperature when Example 1 shown in FIG. 1 is applied to garbage with a moisture of 50%. It is a graph which shows the calculated value of the flame temperature when Example 1 shown in FIG. 1 is applied to the waste of 60% moisture. It is a graph which shows the calculated value of the flame temperature when Example 1 shown in FIG. 1 is applied to the waste of 70% moisture. It is a systematic diagram which shows the principal part structure of the gasification melting system which concerns on Example 2 of this invention. It is a systematic diagram which shows the principal part structure of the gasification melting system which concerns on Example 3 of this invention. It is a systematic diagram which shows the principal part structure of the gasification melting system which concerns on Example 4 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Oxygen generator 2 Air suction piping 3 Boiler 4 Piping 5 Supply chute 6 Gasification furnace 7 Bypass valve 8 Fluidized bed 9 Melting furnace 10 Dust collector 11 Slag discharge device 12a-12h Flue 13 Gas quench tower 14 Air heater 15 Dust collection Vessel 16 induction blower 17 chimney 18 damper 19 blower 20, 21a, 21b, 22, 23, 24a, 24b piping 25 ash stabilization device 26-29, 40, 41, 43, 46, 49, 50 piping 30 circulating blower 31, 42 Thermometer 32, 35, 38, 44 Controller 33, 36, 39, 45, 47, 48 Control valve 34, 37 O ₂ meter 51 Valve 52, 53 Interlocking valve 55 Blower 57, 58 Oil quantity valve 59 Piping 60 Manual Valve 61 Bypass valve 62 Manual valve 63 Start burner 64 Start burner 65 Oil piping 66 Oil piping 67, 68, 69 Tube 70 manual valve 71, 72 combustion air pipe

Claims (10)

Waste gas is gasified in a fluidized bed gasifier using oxygen as a gasifying agent, and the resulting pyrolysis gas and solids are burned and melted in a melting furnace, and the exhaust gas from the melting furnace is discharged outside through a flue. A part of the exhaust gas is extracted from the flue on the downstream side of the melting furnace, and the extracted exhaust gas is supplied to the fluidized bed gasification furnace and the melting furnace as a circulating exhaust gas and burned into the melting furnace. A refuse gasification and melting method comprising a procedure for supplying oxygen for the waste. 2. The refuse gasification and melting method according to claim 1, wherein oxygen and circulating exhaust gas are mixed in advance and then supplied to a fluidized bed gasification furnace and a melting furnace. In the waste gasification and melting method according to claim 1 or 2, the amount of circulating exhaust gas supplied to the fluidized bed type gasification furnace is such that the gas flow rate of the fluidized bed portion is equal to or higher than the flow start speed of the in-layer medium only by circulating exhaust gas. In addition, the amount of oxygen supplied to the fluidized bed gasification furnace is set to be less than the scattering speed of the in-bed medium, the fluidized bed temperature is detected, and the detected fluidized bed temperature is higher than the preset temperature. A refuse gasification and melting method characterized by being controlled to decrease when it is high and to increase when the detected fluidized bed temperature is lower than a preset temperature. The amount of circulating exhaust gas supplied to the melting furnace by detecting the temperature in the furnace or the furnace outlet of the melting furnace and using the detected temperature as an input in the refuse gasification melting method according to any one of claims 1 to 3. A waste gasification and melting method, wherein the temperature of the melting furnace is controlled by controlling the temperature. The refuse gasification and melting method according to any one of claims 1 to 4, wherein the combustion of the fluidized bed gasification furnace and the starting burner of the melting furnace is performed when the fluidized bed gasification furnace and the melting furnace are started. A waste gasification and melting method characterized by igniting a starting burner while supplying air sucked from the atmosphere as an oxidant for the use. Fluidized bed gasification furnace that pyrolyzes and gasifies garbage, melting furnace that burns and melts the pyrolysis gas and solid content obtained in the fluidized bed gasification furnace, and exhaust gas discharged from the melting furnace A flue that leads to the flue, an exhaust gas extraction pipe that branches off the flue, and a suction side connected to the exhaust gas extraction pipe. A circulating blower that is fed as a gasifier, and a gasifier oxygen supply pipe that is connected to the fluidized bed gasifier and that supplies oxygen to the fluidized bed gasifier through a gasifier oxygen control valve capable of opening control A melting furnace oxygen supply pipe for supplying oxygen to the melting furnace via a melting furnace oxygen control valve connected to the melting furnace and capable of opening control, and a part of the circulating exhaust gas pressurized by the circulation fan. Gasifier circulation supplied to the gasifier through a valve A gas supply pipe, a melting furnace circulating exhaust gas supply pipe for supplying the other part of the circulating exhaust gas pressurized by the circulation fan to the melting furnace via a melting furnace circulating exhaust gas control valve capable of opening control, and A fluidized bed thermometer for detecting and outputting the fluidized bed temperature of the fluidized bed gasifier, and a gasifier oxygen control means for controlling the opening of the gasifier oxygen control valve by using the output of the fluidized bed thermometer as an input. A melting furnace thermometer for detecting and outputting the temperature of the melting furnace, a melting furnace circulating exhaust gas control means for controlling the opening degree of the melting furnace circulating exhaust gas control valve using the output of the melting furnace thermometer as an input, An oxygen concentration meter that detects and outputs the oxygen concentration of the exhaust gas in the flue on the exit side of the melting furnace, and a melting furnace oxygen control means that controls the opening of the melting furnace oxygen control valve by using the output of the oxygen concentration meter as an input, The gasifier oxygen supply distribution And the gasification furnace circulation exhaust gas supply pipe are joined to each other at the downstream side of the gasification furnace oxygen control valve and the downstream side of the valve interposed in the gasification furnace circulation exhaust gas supply pipe. A refuse gasification and melting device connected to a gasification furnace and configured to flow into a fluidized bed gasification furnace in a mixed state with oxygen and circulating exhaust gas. The waste gasification and melting apparatus according to claim 6, wherein the gasification furnace oxygen control means reduces the amount of oxygen supplied to the gasification furnace when the fluidized bed temperature is higher than a predetermined temperature range, and the fluidized bed temperature. Is lower than the predetermined temperature range, the opening degree of the gasifier oxygen control valve is controlled so as to increase the amount of oxygen supplied to the gasifier, and the melting furnace circulating exhaust gas control means Increase the amount of circulating exhaust gas supplied to the melting furnace if it is higher than the predetermined temperature range, and reduce the amount of circulating exhaust gas supplied to the melting furnace if the temperature of the melting furnace is lower than the predetermined temperature range In addition, the melting furnace circulating exhaust gas control valve is controlled by opening the melting furnace oxygen control means so that the oxygen concentration of the exhaust gas in the outlet flue of the melting furnace is higher than a predetermined concentration range. Reduce the amount of oxygen to be supplied Waste gasification and melting, each configured to control the opening of the melting furnace oxygen control valve so as to increase the amount of oxygen supplied to the melting furnace when it is lower than the defined concentration range apparatus. 8. The refuse gasification and melting apparatus according to claim 7, wherein the melting furnace oxygen supply pipe and the melting furnace circulation exhaust gas supply pipe are respectively provided downstream of the melting furnace oxygen control valve and downstream of the melting furnace circulation exhaust gas control valve. The refuse gasification and melting apparatus is configured to join each other and to be connected to the melting furnace through the same pipe and to flow into the melting furnace in a state where oxygen and the circulating exhaust gas are mixed. The refuse gasification and melting apparatus according to any one of claims 6 to 8, wherein an air suction pipe branched to the suction side pipe of the circulation blower and connected to the atmosphere is connected, and the discharge side of the circulation blower is connected to the discharge side of the circulation blower. A refuse gasification and melting apparatus, wherein the piping is connected to the combustion air piping of the gasification furnace starting burner and the combustion air piping of the melting furnace starting burner, respectively. 9. The refuse gasification and melting apparatus according to claim 6, wherein a discharge side is connected to the combustion air piping of the gasification furnace starting burner and the combustion air piping of the melting furnace starting burner separately from the circulation blower. A refuse gasification and melting apparatus, characterized in that a blower connected to the suction side is connected to the atmosphere.

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