JP2002130647A - Method and apparatus for controlling combustion of melting furnace in refuse gasification melting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To operate a melting furnace by reducing auxiliary combustion rate while keeping intended temperature. SOLUTION: Control structure of a refuse gasification melting furnace of char separation type is provided. In the structure, stable supply of char, which is an advantage of the furnace, is sufficiently utilized, and even if there is a disturbance, such as calorific value variation of refuse, manipulated variable of char supply rate, auxiliary combustion rate, air supply rate or the like can be calculated so that controlled variable such as of gas temperature in the furnace satisfies operation requirements, by using a map control technique. Thus operation with combustion air rate of around 1 is rendered possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a map combustion control method for a char separation type refuse gasification / melting furnace in which the amount of char supplied, the amount of auxiliary combustion, and the amount of air are optimized even when the amount of generated heat is changed. And an apparatus.

[0002]

2. Description of the Related Art A refuse gasification and melting plant once gasifies refuse in a gasification furnace and then uses the calorie of the generated unburned ash to melt the ash in the refuse into slag. One of the characteristics of refuse combustion is that refuse as fuel has non-uniform physical and chemical properties. For this reason, even if the speed of the dusting apparatus is constant, the amount of dust supplied to the furnace varies due to the unevenness of the shape and volume of the dust.
Also, since the component ratio of garbage, such as the water content ratio, changes,
The lower calorific value of refuse varies. These fluctuations are "disturbance factors" that hinder the stability of the waste incineration plant. Therefore, in the non-separated garbage gasification and melting system in which the unburned gas and unburned ash (hereinafter referred to as char) generated in the gasification furnace are put into a melting furnace and simultaneously treated, the supply amount of the refuse is changed. The variation in the calorific value acts as a disturbance factor in a synergistic manner, and its influence is great.

Further, as a conventional technique, for example, Japanese Patent Laid-Open No.
Japanese Patent Application Publication No. 00-154913 discloses a system in which refuse is gasified in a gasification furnace, and the generated combustible gas (unburned gas) and unburned char are burned at a high temperature in a melting furnace to discharge combustion exhaust gas and slag. And a method of measuring the CO and CO ₂ concentrations of the gas and controlling the amount of air supplied to the gasification furnace based on the calculation result of CO / CO ₂ . The above-mentioned refuse gasification and melting system is a char non-separation system, in which the char and the unburned gas are simultaneously supplied to the melting furnace. Further, in the above system, the combustion control operation in the melting furnace is not performed. Furthermore, the above technology is based on the analysis of flammable gas using a CO meter and a CO ₂ meter, and its usefulness is questionable due to the difficulty of measurement in refuse combustion.

[0004]

In order to operate the melting furnace while reducing the amount of auxiliary combustion and maintaining the target temperature, the amount of heat input to the melting furnace is stabilized according to the load setting, and the combustion air ratio is set close to 1. It is required to hold. However, as mentioned above,
In a non-separated char gasification and melting system in which unburned gas and char generated in the gasification furnace are simultaneously injected into the melting furnace,
Since the variation in the amount of supplied char and the variation in the amount of generated heat of the char act as disturbance factors in a synergistic manner, it is difficult to control the operation so that the combustion air ratio is close to 1. That is, in the case of the non-separation method in which the variation in the amount of supplied char and the variation in the amount of generated heat are synergistic, the variation in the gas temperature in the furnace is large, and the stable combustion of the melting furnace is significantly inhibited.

On the other hand, in a garbage gasification and melting system of the char separation type in which the char is separated from the char generated in the gasifier and the unburned gas and supplied to the melting furnace, the char can be supplied stably. Disturbances to be considered can be narrowed down to fluctuations in the calorific value. In this case, in order to operate with the combustion air ratio kept close to 1, if the char heating value fluctuation is dealt with by system control of the auxiliary combustion amount and the air amount, due to the non-linearity of the target furnace gas temperature characteristics, the required It is difficult to meet operating conditions.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide a char separation type refuse gasification / melting furnace, which makes full use of the stable supply of char, which is a feature of the refuse gasification / melting furnace. By using
Even if there is disturbance such as fluctuation of calorific value, the amount of char supply,
An operation amount such as an auxiliary combustion amount and an air amount can be calculated so that a control amount such as a furnace gas temperature satisfies an operation condition,
By enabling operation at a combustion air ratio of around 1,
An object of the present invention is to provide a method and an apparatus for controlling the combustion of a melting furnace which can realize a stable and low-cost operation while maintaining a target temperature by reducing the amount of auxiliary combustion.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, a method of controlling combustion in a melting furnace in a refuse gasification melting furnace according to the present invention comprises the steps of: After generating gas and separating char and ash from the unburned gas, the unburned gas is burned to recover heat, and the separated char and ash are supplied to a melting furnace to burn the char to melt the ash to form slag. In the waste gasification and melting furnace, the calorific value of the char and the air ratio of the melting furnace are estimated from the process data of the melting furnace and are used for correcting the combustion control of the melting furnace.

[0008] The method of the present invention further comprises the steps of gasifying refuse in a gasifier to generate unburned gas containing char and ash, separating char and ash from the unburned gas, and burning the unburned gas. In a refuse gasification and melting furnace in which char and ash are supplied to a melting furnace to burn the char and melt the ash to make slag, a melting furnace combustion control map is created from process data of the melting furnace. It is characterized by performing the melting furnace operation by map control.

[0009] The method of the present invention further comprises the step of gasifying refuse in a gasifier to generate unburned gas containing char and ash, separating the char and ash from the unburned gas, and burning the unburned gas. In the refuse gasification and melting furnace that supplies the separated char and ash to the melting furnace and burns the char to melt the ash to make slag, the char calorific value and the melting furnace air ratio are calculated from the melting furnace process data. Estimate, correct the calorific value from the estimated calorific value, and perform control in accordance with the melting furnace combustion control map. It is characterized in that the melting furnace is operated by performing control in conjunction with.

[0010] The method of the present invention further comprises the steps of gasifying refuse in a gasifier to generate unburned gas containing char and ash, separating char and ash from the unburned gas, and burning the unburned gas. In the refuse gasification and melting furnace that supplies the separated char and ash to the melting furnace and burns the char to melt the ash to make slag, the char calorific value and the melting furnace air ratio are calculated from the melting furnace process data. Estimate, correct the calorific value set value from the char calorific value estimate, calculate the auxiliary combustion amount, air amount, etc. according to the melting furnace combustion control map from the furnace gas temperature, char processing amount, char calorific value, etc. The melting furnace is operated by correcting the set value of the melting furnace air ratio from the estimated value of the melting furnace air ratio and performing control in conjunction with the melting furnace combustion control map.

A melting furnace combustion control apparatus for a refuse gasification and melting furnace according to the present invention comprises: a gasifier for gasifying refuse in a reducing atmosphere; a cyclone connected to a gas outlet of the gasifier; A boiler connected to the upper part via an unburned gas conduit and a char-
In a refuse gasification / melting furnace having a melting furnace connected via an ash transfer line, operating conditions (furnace gas temperature, char treatment amount, A main control device incorporating an arithmetic circuit capable of calculating an operation amount (amount of auxiliary combustion, an amount of air, etc.) from a calorific value of the char,
It is characterized by comprising a correction device for correcting a set value of an operating condition (char heat generation amount or the like) and each system control device for controlling each control amount according to an operation amount output from a main control device.

Further, the apparatus of the present invention comprises a gasifier for gasifying refuse in a reducing atmosphere, a cyclone connected to a gas outlet of the gasifier, and an unburned gas conduit above the cyclone. Waste gasification and melting furnace equipped with a boiler connected to the furnace and a melting furnace connected to the lower part of the cyclone via a char and ash transfer line, the char calorific value and the melting furnace air ratio are obtained from the melting furnace process data. A calorific value / melting furnace air ratio estimating circuit, an operating condition setting correction circuit for correcting the char calorific value set value from the char calorific value estimation value, and melting from the furnace gas temperature, char processing amount and char calorific value An arithmetic circuit for calculating the auxiliary combustion amount and the air amount according to the furnace combustion control map; and each control amount based on the auxiliary combustion amount and the air amount calculated by the arithmetic circuit according to the melting furnace combustion control map. It is your, and is characterized in that the control in conjunction with the melting furnace combustion control map by correcting the melting furnace air ratio setting value from the melting furnace air ratio estimates is composed of a control circuit to be performed.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments and can be implemented with appropriate modifications. FIG. 1 shows a waste gasification and melting system used in the first embodiment of the present invention. In the present embodiment, a case where a fluidized-bed gasification furnace is used as a gasification furnace and a swirling melting furnace is used as a melting furnace, but other types of gasification furnaces and melting furnaces can be used. In FIG.
Reference numeral 10 denotes a fluidized-bed gasifier, and a cyclone 14 is connected to a free board 12 of the gasifier 10. Although the fluidized bed gasifier 10 is of the diffuser type in FIG. 1, it is of course possible to use an air distribution plate type. The upper part of the cyclone 14 is the partial combustion gas conduit 1
The boiler 18 is connected to a burner (not shown) provided on a furnace wall near a lower portion of a reburning section (reburning chamber) 20 of the boiler 18. The heat recovery unit 22 of the boiler 18 includes superheaters 24, 2
6, evaporators 28 and 30 are provided. 32 is a steam turbine and 34 is a generator. Although not shown, an air preheater is connected to the boiler 18 via an exhaust gas conduit, and a cooling tower is connected to the air preheater via an exhaust gas conduit.

In the lower part of the cyclone 14, a char
A swirling melting furnace 38 is connected via an ash transfer line 36. A hopper 40 temporarily stores unburned char and ash. The swirling melting furnace 38 includes a pre-combustion unit 42 that supplies char and ash, combustion air, and, if necessary, an auxiliary fuel to perform pre-combustion, and a substantially cylindrical shape in which the pre-combustion unit 42 is tangentially connected. The slag melting section 44 includes a slag water sealing hopper 48 connected to the lower surface of the slag melting section 44 via a slag flow outlet 46. An exhaust gas outlet of the swirling melting section 44 of the melting furnace 38 is connected to a heat recovery section 22 (for example, downstream of the superheater) of the boiler 18 via a melting furnace exhaust gas conduit 50.

Next, the operation of the apparatus shown in FIG. 1 will be described. The refuse introduced into the fluidized-bed gasification furnace 10 as a partial combustion furnace by the dust supply device 52 is thermally decomposed in a reducing atmosphere having an air ratio of about 0.2 to 0.3 in a fluidized bed of about 500 to 600 ° C. , Partial combustion gas (unburned gas), unburned char and ash are generated. Partial combustion gas including char and ash is supplied from the free board 12 of the gasifier 10 to the cyclone 1.
4 and is separated into partial combustion gas and char and ash. The separated partial combustion gas is supplied to the partial combustion gas conduit 1
6 and is introduced into a burner (not shown) provided on the furnace wall near the lower portion of the reburning section 20 of the boiler 18. In the burner, the partial combustion gas is mixed with combustion air and burns, and the combustion exhaust gas is introduced into the reburning section 20. Then, by generating high-temperature superheated steam in the heat recovery unit 22 (superheater) of the boiler 18, power is generated by the steam turbine generator. On the other hand, the separated char and ash are supplied to the pre-combustion unit 42 of the swirling melting furnace 38 together with combustion air and, if necessary, auxiliary fuel, where most of the char is burned. The pre-combustion gas from the pre-combustion section 42 is tangentially introduced into the substantially cylindrical swirl / melting section 44, and
While burning at a high temperature of about 300 to 1400 ° C., most of the ash melts and turns into slag, falls into the slag water seal hopper 48, is cooled and becomes water-cooled slag, and is taken out by a discharger such as a conveyor. The high-temperature exhaust gas from the swirling melting section 44 is introduced into the heat recovery section 22 (for example, downstream of the superheater) of the boiler 18 via the melting furnace exhaust gas conduit 50.

In the above-described refuse gasification and melting system using the char separation method, since the amount of char supplied to the melting furnace can be quantified, disturbance factors that hinder stable combustion in the melting furnace are limited to fluctuations in the calorific value. Thus, it is possible to suppress disturbance factors of refuse combustion and to operate at a combustion air ratio near 1 by the map control described below. As a result, stable and low-cost operation in which the amount of auxiliary combustion is reduced and the target temperature is maintained can be realized. FIG. 2 shows a configuration of an apparatus for performing a melting furnace combustion control method in a waste gasification melting furnace according to the first embodiment of the present invention. As shown in FIG. 2, the configuration in the present embodiment is a melting furnace operation map circuit 54.
, A calorific value / melting furnace air ratio estimating circuit 56, an operating condition setting correcting circuit 58, and a system control circuit 60. These circuits function by being built in a digital computer.

Next, the creation of the melting furnace operation map (melting furnace combustion control map) and the estimation of the char calorific value and the melting furnace air ratio will be described. The revolving melting furnace is centralized and the description focuses on the energy balance type. The theoretical air amount and the theoretical gas amount follow the Rosin equation. An example of the mathematical formula group is shown in the following formulas 1 to 9. The symbols used in the present formula group are as shown in Table 1. Note that a ₁ , b ₁ , a ₂ , and b ₂ in Equation (3) of Equation 4 are constants determined so that the equation of λt <1 and the equation of λt ≧ 1 maintain continuity.

[0018]

(Equation 1)

[0019]

(Equation 2)

[0020]

(Equation 3)

[0021]

(Equation 4)

[0022]

(Equation 5)

[0023]

(Equation 6)

[0024]

(Equation 7)

[0025]

(Equation 8)

[0026]

(Equation 9)

[0027]

[Table 1]

(1) Preparation of a melting furnace combustion control map The process data is substituted into a group of formulas to calculate a melting furnace combustion control map. The calculation process is shown below. FIG. 3 shows the flow of the calculation process. Input reference Huc (char heat generation amount) from Qts (heat input amount setting) and Gcs (char processing amount setting) and calculate Goil (auxiliary combustion amount) from equation (1) ′ (Huoil (heavy oil heat generation amount) fixed ). In equation (2), the air ratio λt = 1, Huc, Goil, Huoil
To calculate Ga (air amount). Gc (char processing amount), λt, Ga, Huc, Goil, H
Substituting uoil and Tg (furnace gas temperature) into equations (1) and (3), Ql (heat release) is calculated. By substituting Ql into equation (6), kq (heat dissipation coefficient) is obtained. The values of Gc and kq are fixed, and Ga and Goil of each Huc are substituted into equations (1) to (3) to obtain a value of Tg for each Huc. It is confirmed that the Tg pattern satisfies the target furnace gas temperature.

(2) Estimation of Char Calorific Value and Melting Furnace Air Ratio The above formulas are solved in the controller, and the char calorific value, melting furnace air ratio, etc. are estimated and used for correction of combustion control. The operation of the melting furnace is controlled in accordance with the above-described control map by correcting the char calorific value set value from the char calorific value estimation value. Further, the set value of the melting furnace air ratio is corrected from the estimated value of the melting furnace air ratio, and control is performed in conjunction with the control map.

As described above, by using a gas separation and melting furnace of the char separation type, stable supply of char is possible, and as a disturbance factor to be considered, it is possible to narrow down the fluctuation of the calorific value of char. As a result of the sensitivity analysis of the furnace gas temperature by the above-mentioned formula group, as shown in FIGS. 4 and 5, when the furnace gas temperature Tg is the highest when operating near λt = 1, and when λt <1. Also, when λt> 1, Tg tends to be lower than when λt = 1. On the other hand, in the case of the char non-separation method in which the fluctuation of the char supply amount and the fluctuation of the calorific value are synergistic, the fluctuation of the in-furnace gas temperature is large, and the stable combustion of the melting furnace is significantly inhibited. In the case of the char separation method of the present invention,
Since it is only a response to the disturbance of the calorific value, operation in the vicinity of λt = 1 makes it possible to operate the melting furnace with the minimum amount of auxiliary combustion, which can contribute to cost reduction.

As a control method when the furnace gas temperature Tg is lowered due to disturbance of the char heat generation amount Huc or the char supply amount Gc, a map control method, a method of increasing Goil + Ga, a method of increasing Gc + Ga, and the like can be considered. Therefore, a comparative study was performed on the characteristics of the control system when the map control was used and when the control using Goil + Ga or Gc + Ga was used. Simulations were performed for the case where the char exotherm Huc was increased and the case where the char exotherm was decreased as a disturbance, in the case where the manipulated variable was not changed and in the case where the above three controls were used. The simulation results of the eight cases shown in Table 2 below are shown in FIGS. Case 1, 2
The results of (no control) are shown in FIGS.
The results of (map control) are shown in FIGS.
6 (Goil increase, Ga increase) are the results in FIGS. 10 and 11,
The results of Cases 7 and 8 (increased Gc and increased Ga) are shown in FIGS.
It is.

[0032]

[Table 2]

As shown in FIGS. 8 and 9, when the map control is used, the in-furnace gas temperature Tg recovers to the initial value.
In other methods, the furnace gas temperature Tg decreased. This means that the map control can determine the operation amount so that λt = 1, but in the method of increasing the auxiliary combustion amount Goil and the char supply amount Gc and increasing the air amount Ga corresponding thereto, λt = 1
Because you can't keep it. Therefore, λt =
The map control that can determine the operation amount to be 1 is an effective control method for keeping the in-furnace gas temperature Tg high.

[0034]

As described above, the present invention has the following effects. (1) In the garbage gasification / melting system using the char separation method, stable supply of char is possible, and as a disturbance to be considered, it is possible to focus on fluctuations in the calorific value of the char, thus exhibiting high controllability. It is. (2) It is possible to operate at a combustion air ratio of around 1, thereby reducing the amount of auxiliary combustion and maintaining the target temperature.
Low cost operation can be realized. (3) Char calorific value can be estimated and corrected without an O ₂ meter, and is highly practical. (4) If it is difficult to measure the furnace temperature due to environmental conditions such as high temperature, it can be replaced by obtaining a calibration curve between the heat recovery amount and the measurement furnace temperature in advance from the melting water and water temperature. It is.

[Brief description of the drawings]

FIG. 1 is a systematic schematic structural explanatory view showing a refuse gasification / melting system used in a first embodiment of the present invention.

FIG. 2 is a systematic conceptual configuration explanatory diagram showing an apparatus for performing a melting furnace combustion control method in a refuse gasification / melting furnace according to a first embodiment of the present invention.

FIG. 3 is a flowchart showing a calculation process of a melting furnace combustion control map.

FIG. 4 is a graph showing the results of sensitivity analysis of the gas temperature in the furnace when only the char supply amount is changed.

FIG. 5 is a graph showing a sensitivity analysis result of a gas temperature in a furnace when only a calorific value of char is changed.

FIG. 6 is a graph showing a simulation result (Case 1) in a case where the manipulated variable is not changed with respect to a change (increase) in the amount of generated heat of the char.

FIG. 7 is a graph showing a simulation result (Case 2) in a case where the manipulated variable is not changed with respect to a change (decrease) in the heat generation amount of the char.

FIG. 8 is a graph showing a simulation result (case 3) when map control is used for a change (increase) in the amount of generated heat of a char.

FIG. 9 is a graph showing a simulation result (Case 4) in a case where map control is used for a change (decrease) in the heat generation amount of a char.

FIG. 10: Goil + Ga against char heating value fluctuation (increase)
9 is a graph showing a simulation result (case 5) when the control according to (1) is used.

FIG. 11: Goil + Ga against char heating value fluctuation (decrease)
9 is a graph showing a simulation result (case 6) when the control according to (1) is used.

FIG. 12 is a graph showing a simulation result (Case 7) in a case where control by Gc + Ga is used for a change (increase) in the amount of generated heat of a char;

FIG. 13 is a graph showing a simulation result (Case 8) in a case where the control by Gc + Ga is used for the change (decrease) in the calorific value of char.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Fluidized bed gasifier 12 Free board 14 Cyclone 16 Partial combustion gas conduit 18 Boiler 20 Reburning part (reburning chamber) 22 Heat recovery part 24, 26 Superheater 28, 30 Evaporator 32 Steam turbine 34 Generator 36 Char and ash Conveying line 38 Rotating melting furnace 40 Hopper 42 Pre-combustion unit 44 Rotating melting unit 46 Slag flow down port 48 Slag water seal hopper 50 Melting furnace exhaust gas conduit 52 Dust feeding device 54 Melting furnace operation map circuit 56 Char calorific value / melting furnace air ratio estimation Circuit 58 Operating condition setting correction circuit 60 Each system control circuit

Continued on the front page (72) Inventor Hidetaka Miyazaki 1-1, Kawasaki-cho, Akashi-shi, Hyogo Prefecture Inside the Akashi Plant of Kawasaki Heavy Industries, Ltd. 72) Inventor Hiroshi Fujiyama 1-3-3 Higashikawasaki-cho, Chuo-ku, Kobe Kawasaki Heavy Industries, Ltd.Kobe Head Office (72) Inventor Noboru 1-3-3 1-3-1, Higashikawasakicho, Chuo-ku, Kobe Kawasaki Heavy Industries, Ltd. Kobe Head Office (72) Inventor Hiroshi Fujita 1-3-1 Higashi Kawasaki-cho, Chuo-ku, Kobe Kawasaki Heavy Industries, Ltd.Kobe Head Office (72) Inventor Kenichi Fujii 1-1-3 Higashi-Kawasaki-cho, Chuo-ku, Kobe Kawa Saki Heavy Industries, Ltd. Kobe Head Office F-term (reference) 3K061 AA11 AA16 AB02 AB03 AC01 BA02 FA02 FA09 FA12 FA21 FA27 3K078 AA02 CA02 CA21 CA25

Claims (6)

[Claims] 1. Gasification of refuse in a gasification furnace to generate unburned gas containing char and ash, separation of char and ash from unburned gas, burning of unburned gas, heat recovery, and separation In the refuse gasification and melting furnace, which supplies the char and ash to the melting furnace and burns the char to melt the ash into slag, the char calorific value and the air ratio of the melting furnace are estimated from the process data of the melting furnace, A method for controlling combustion of a melting furnace in a refuse gasification / melting furnace, wherein the method is used for correcting combustion control. 2. Gasification of refuse in a gasifier to generate unburned gas containing char and ash, separating char and ash from the unburned gas, burning the unburned gas, recovering heat, and separating. In a refuse gasification and melting furnace, which supplies the char and ash to the melting furnace and burns the char to melt the ash to produce slag, a melting furnace combustion control map is created from the melting furnace process data, and the melting furnace operation by map control A combustion control method for a melting furnace in a refuse gasification melting furnace. 3. Gasification of refuse in a gasifier to generate unburned gas containing char and ash, separating char and ash from the unburned gas, burning the unburned gas, recovering heat, and separating. In a refuse gasification and melting furnace in which the char and ash supplied to the melting furnace are burned and the ash is melted to make slag, the calorific value of the char and the air ratio of the melting furnace are estimated from the process data of the melting furnace, and the calorific value of the char is calculated. Correct the char heating value from the estimated value and perform control in accordance with the melting furnace combustion control map, correct the melting furnace air ratio setting from the estimated melting furnace air ratio, and control in conjunction with the melting furnace combustion control map. A melting furnace combustion control method in a refuse gasification / melting furnace, wherein the melting furnace is operated by performing the method. 4. Gasification of refuse in a gasifier to generate unburned gas containing char and ash, separating char and ash from the unburned gas, burning the unburned gas, recovering heat, and separating. In a refuse gasification and melting furnace in which the char and ash supplied to the melting furnace are burned and the ash is melted to make slag, the calorific value of the char and the air ratio of the melting furnace are estimated from the process data of the melting furnace, and the calorific value of the char is calculated. The calorific value set value is corrected from the estimated value, the auxiliary combustion amount and the air amount are calculated and controlled based on the furnace gas temperature, char processing amount and char calorific value according to the melting furnace combustion control map, and the melting furnace air ratio estimated value A method for controlling the combustion of a melting furnace in a refuse gasification / melting furnace, wherein the melting furnace is operated by correcting a set value of an air ratio of the melting furnace and performing control in conjunction with a combustion control map of the melting furnace. 5. A gasifier for gasifying refuse in a reducing atmosphere, a cyclone connected to a gas outlet of the gasifier, and a boiler connected to an upper portion of the cyclone via an unburned gas conduit. In a refuse gasification / melting furnace provided with a melting furnace connected to a lower part of the cyclone via a char / ash transfer line, a calculation capable of calculating an operation amount from an operation condition so that the control amount satisfies the operation condition A main control device incorporating a circuit, a correction device for correcting a set value of an operating condition, and a system control device for controlling each control amount according to an operation amount output from the main control device. Melting furnace combustion control device in the garbage gasification melting furnace. 6. A gasifier for gasifying refuse in a reducing atmosphere, a cyclone connected to a gas outlet of the gasifier, and a boiler connected to an upper portion of the cyclone via an unburned gas conduit. In a refuse gasification / melting furnace having a melting furnace connected to a lower part of the cyclone via a char / ash transfer line, a char heating value for estimating a char heating value and a melting furnace air ratio from process data of the melting furnace.・ Melting furnace air ratio estimating circuit, operating condition setting correction circuit to correct char calorific value set value from char calorific value estimation value, and assist combustion according to melting furnace combustion control map from furnace gas temperature, char processing amount and char calorific value An arithmetic circuit for calculating the amount of air and the amount of air; and each control amount is system-controlled based on the auxiliary combustion amount and the amount of air calculated by the arithmetic circuit in accordance with the melting furnace combustion control map. A control circuit for correcting the set value of the melting furnace air ratio from the estimated value of the furnace air ratio and performing control in conjunction with the melting furnace combustion control map, wherein the melting furnace combustion in the refuse gasification melting furnace is performed. Control device.