JP6126559B2 - Operation method of gasification melting furnace - Google Patents

Description

  The present invention relates to a melting furnace for burning combustible gas flowing from a gasification furnace and melting ash contained in the combustible gas.

  Conventionally, a gasification melting furnace including a gasification furnace and a melting furnace is known. For example, Patent Document 1 discloses a gasification melting furnace including a fluidized bed gasification furnace, a swirling flow melting furnace, and a duct connecting the upper part of the fluidized bed gasification furnace and the upper part of the swirling flow melting furnace. Is disclosed.

  A fluidized bed gasification furnace is a furnace that takes out combustible gas from the waste by heating the waste in the fluidized bed. The combustible gas generated in the gasification furnace and the ash contained in the gas are introduced into the swirling flow melting furnace through the duct.

  The swirl flow melting furnace is a furnace that burns the combustible gas while melting the ash while forming a swirl flow with the combustible gas. Specifically, the swirl-flow melting furnace is provided on the top wall of the furnace body having a combustible gas inlet and a tap outlet for discharging molten slag formed by melting the ash. And a burner.

  The furnace main body is a combustion chamber that swirls combustible gas flowing in from the inlet, a slag discharge chamber that is connected to the lower part of the combustion chamber and guides the molten slag to the outlet, and a slag discharge chamber And a gas discharge chamber for discharging the exhaust gas after burning in the combustion chamber to the outside of the furnace body. The combustion chamber is formed in a cylindrical shape that is long in the vertical direction. The inlet is formed in the upper part of the side wall of the combustion chamber. A burner is provided on the top wall of the combustion chamber so that the flame extends downward from the top wall. This burner is provided to raise or maintain the furnace top temperature at the upper part of the combustion chamber to a temperature at which the combustible gas flowing in from the inlet ignites. The burner is supplied with fuel and burner air. The slag discharge chamber has a shape that extends obliquely downward from the lower end of the combustion chamber and is connected to the outlet. The diameter of the boundary between the combustion chamber and the slag discharge chamber is designed to be smaller than the diameter of the combustion chamber. The molten slag formed by melting the ash in the combustion chamber flows down obliquely along the bottom wall of the slag discharge chamber and is discharged from the outlet. The gas discharge chamber has a shape extending from the tap outlet to the side opposite to the slag discharge chamber and obliquely upward.

  This gasification melting furnace is operated as follows.

  First, waste is supplied to the fluidized bed of the fluidized bed gasifier, where the waste is heated. The combustible gas generated at this time flows into the combustion chamber from the inlet through the duct.

  In the swirling flow melting furnace, fuel and burner air are supplied to the burner so that the temperature in the combustion chamber is maintained at a high temperature (the temperature at which the ash contained in the combustible gas melts). Usually, burner air is supplied in such an amount that the ratio of air to fuel is 1.0 to 1.3 so that the fuel supplied to the burner is completely combusted. In this state, the combustible gas flowing in from the inflow port burns while forming a swirl flow in the combustion chamber. The ash in the combustible gas is melted by the heat generated at this time and separated from the combustible gas. The molten slag formed by melting the ash flows down on the side wall of the combustion chamber and the bottom wall of the slag discharge chamber and is discharged from the outlet. The exhaust gas after burning in the combustion chamber is discharged downstream through the gas discharge chamber.

Japanese Patent No. 4833270

  In the melting furnace as described in Patent Document 1, deposits (melting temperature) formed by cooling the molten slag on the downstream side of the tap outlet, more specifically, on the bottom wall of the gas discharge chamber. High slag, etc.) may adhere. If deposits adhere to the bottom wall of the gas discharge chamber, the flow path of the exhaust gas in the gas discharge chamber becomes narrow, and the pressure loss that occurs when the exhaust gas passes through the gas discharge chamber increases. Therefore, when the deposit adheres to the bottom wall of the discharge chamber, generally, the burner is in a state where the fuel supply amount and the burner air supply amount are increased so that the air ratio to the fuel is maintained constant. Then, the temperature in the furnace body is increased by continuing to burn the fuel, and thereby the deposit is melted and removed. However, since the fuel is continuously burned by the burner until the temperature of the deposit attached on the bottom wall of the gas discharge chamber becomes high enough to melt, the amount of fuel consumption increases.

  An object of the present invention is to provide a method for operating a gasification melting furnace capable of removing deposits adhering to the bottom wall of a gas discharge chamber located downstream of the melting furnace outlet with a small amount of fuel. It is to be.

  As a means for solving the above-mentioned problems, the present invention provides a gasification melting furnace operating method comprising a gasification furnace and a melting furnace, wherein the combustible gas is produced by heating waste as the gasification furnace. A gasification furnace preparation step for preparing what can be generated, a combustion chamber having an inflow port for the combustible gas and burning the combustible gas as the melting furnace, obliquely downward from a lower portion of the combustion chamber A slag discharge chamber that leads molten slag formed by melting ash contained in the combustible gas in the combustion chamber to the outlet, and the side opposite to the slag discharge chamber from the outlet A furnace body having a bottom wall extending toward the bottom and having a gas discharge chamber for discharging exhaust gas after combustion in the combustion chamber, and a top wall of the combustion chamber so that the flame extends downward Burner, A melting furnace preparation step for preparing what to have, and an adhesion condition indicating that an adhering material has adhered or is expected to adhere to at least a portion of the furnace body upstream of the tap port A normal operation step of sometimes burning the combustible gas flowing into the combustion chamber from the inflow port by supplying fuel and burner air to the burner and melting the ash contained in the combustible gas; When the deposit adheres on the bottom wall of the gas discharge chamber, the ratio of fuel to the amount of fuel supplied in the normal operation process is larger than that in the normal operation process. A gas-operating operation step of extending the flame downward by supplying a quantity of the burner air to the burner to melt the deposits It provides a method of operating a melting furnace.

  In this method, by operating the burner at an appropriate air ratio when the adhesion condition is satisfied in the normal operation process, the combustible gas can be effectively burned and the ash can be melted, while the gas discharge chamber When deposits such as slag with a high melting temperature adhere to the bottom wall of the fuel, the amount of fuel and air to fuel is larger than that in the normal operation process. By supplying the burner air to the burner and extending the flame downward, the fuel supply amount and the burner air supply amount are normally operated so that the air to fuel ratio is maintained the same as that of the normal operation process. The gas discharge chamber can be maintained at a higher temperature than when the fuel is burned in the normal increase state increased from the process. Specifically, since the position of the lower end (tip) of the flame in the operation process at the time of adhesion is closer to the gas discharge chamber than that in the normal operation process and the normal increase state, the air ratio in the normal operation process and the normal increase state In comparison with the case where the burner is continuously operated, the gas discharge chamber can be maintained at a higher temperature by operating the burner at the air ratio in the operation process at the time of adhesion. Therefore, in this operation method, when the deposit adheres while burning the combustible gas and melting the ash in the normal operation process, a larger amount of fuel and air to the fuel than the amount of fuel supplied in the normal operation process are obtained. By supplying to the burner an amount of burner air whose ratio is larger than that in the normal operation process, the gas discharge chamber can be maintained at a higher temperature and the amount of fuel used can be reduced.

  In this case, in the operation process at the time of adhesion, the burner air is used in such an amount that the air ratio is larger than the air ratio to the fuel in the normal operation process and that the lower end of the flame reaches the slag discharge chamber. It is preferable to supply.

  In this way, the temperature of the gas discharge chamber is easily maintained at a higher temperature, so that the fuel is further reduced.

  Specifically, in the normal operation process, the burner air is supplied in an amount such that the air ratio to the fuel is 1.0 to 1.3. In the operation process during adhesion, the air ratio to the fuel is 1. You may supply the said air for burners of the quantity used as 5 or more.

  In the present invention, in the normal operation step and the attachment operation step, combustion air is supplied to the combustion chamber to assist combustion of the combustible gas, and this supply is performed in a lower portion of the combustion chamber. It is preferable to perform the adjustment while adjusting the supply amount of the combustion air so that the total air ratio to the combustible gas and the fuel is constant.

  In this way, since the combustible gas and the fuel are effectively burned in the combustion chamber, the combustion chamber can be effectively maintained at a high temperature in both the normal operation process and the adhesion operation process. Specifically, in the operation process at the time of adhesion, the supply amount of combustion air is adjusted according to the supply amount of burner air so that the total air ratio is the same as that in the normal operation process.

  As described above, according to the present invention, a gasification melting furnace capable of removing deposits adhering to the bottom wall of the gas discharge chamber located on the downstream side of the melting furnace outlet with a small amount of fuel. It is possible to provide a driving method.

It is a figure which shows the outline of the gasification melting furnace of one Embodiment of this invention. It is a figure which shows the state which the deposit | attachment adhered on the bottom wall of the gas discharge chamber of the gasification melting furnace shown in FIG.

  A fluidized bed gasifier according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

  As shown in FIG. 1, the gasification melting furnace of the present embodiment connects a fluidized bed gasification furnace 10, a swirling flow melting furnace 20, a fluidized bed gasification furnace 10, and a swirling flow melting furnace 20. And a duct 50.

  The fluidized bed gasification furnace 10 is a furnace that takes out combustible gas from the waste by heating the waste in the fluidized bed 14. Specifically, the fluidized bed gasification furnace 10 includes a furnace body 12 and a fluidized medium 13 that forms a fluidized bed 14.

  The furnace body 12 is formed in a cylindrical shape that is long in the vertical direction. A supply port 12 a for supplying waste is provided at a side portion of the furnace body 12, and an outlet 12 b for allowing the combustible gas to flow out of the furnace body 12 at the top of the furnace body 12. Is provided. A bottom wall 16 that supports the fluid medium 13 from below is provided in the furnace body 12.

  The fluidized bed gasifier 10 is operated as follows.

  First, a fluidizing gas for fluidizing the fluid medium 13 is supplied through the bottom wall 16. Thereby, the fluidized bed 14 is formed. Next, waste is supplied to the fluidized bed 14 through the supply port 12a. If it does so, combustible gas will generate | occur | produce by waste-burning partially in the fluidized bed 14. The combustible gas and the ash contained in the gas flow out of the furnace body 12 from the outlet 12b, and flow into the swirling flow melting furnace 20 through the duct 50. On the other hand, the mixture of the incombustible material and the fluid medium 13 that remains without being combusted in the fluidized bed 14 is discharged to the lower side of the furnace body 12 through the discharge port 16 a formed at the approximate center of the bottom wall 16.

  The swirl flow melting furnace 20 is a furnace that burns the combustible gas while melting the ash while forming a swirl flow with the combustible gas. Specifically, the swirling flow melting furnace 20 is provided in the furnace main body 30 having a combustible gas inlet 30a and an outlet 30b for discharging molten slag formed by melting the ash. Burner 42.

  The furnace body 30 has an inlet 30a, a combustion chamber 32 that burns combustible gas flowing in from the inlet 30a while swirling, a slag discharge chamber 36 that guides the molten slag to the outlet 30b, and a combustion chamber And a gas discharge chamber 38 for discharging the exhaust gas after burning at 32 to the outside of the furnace body 30.

  The combustion chamber 32 is formed in a cylindrical shape that is long in the vertical direction. The combustion chamber 32 has a cylindrical side wall 33 and a top wall 34 connected to the upper end of the side wall 33. The inflow port 30 a is formed in the upper part of the side wall 33.

  The slag discharge chamber 36 is connected to the lower part of the combustion chamber 32. Specifically, the slag discharge chamber 36 has a shape that extends obliquely downward from the lower end of the combustion chamber 32 and is connected to the tap outlet 30b. The diameter of the boundary 35 between the combustion chamber 32 and the slag discharge chamber 36 is designed to be smaller than the diameter of the side wall 33 of the combustion chamber 32. The molten slag formed by melting the ash in the combustion chamber 32 flows down obliquely along the bottom wall 37 of the slag discharge chamber 36 and is discharged from the outlet 30b.

  The gas discharge chamber 38 is connected to the downstream side of the slag discharge chamber 36. Specifically, the gas discharge chamber 38 has a shape extending from the tap outlet 30b on the opposite side to the slag discharge chamber 36 and obliquely upward. The gas discharge chamber 38 has a bottom wall 39 having a shape extending obliquely upward from the tap hole 30b, and an opposing wall 40 facing the bottom wall 39 in the vertical direction.

  The burner 42 is provided on the top wall 34 so that the flame 44 extends downward from the top wall 34. The burner 42 is provided to raise or maintain the furnace top temperature in the upper part of the combustion chamber 32 to a temperature at which the combustible gas flowing in from the inlet 30a ignites. The burner 42 is supplied with fuel f and burner air a1.

  The swirling flow melting furnace 20 described above is normally operated as follows.

  That is, there is an adhesion condition indicating that deposits have adhered or are expected to adhere to at least a portion of the furnace body 30 upstream of the tap outlet 30b (such as the combustion chamber 32 and the slag discharge chamber 36). When established, the fuel f and burner air a1 are supplied to the burner 42 to burn the combustible gas flowing into the combustion chamber 32 from the inlet 30a and to melt the ash contained in the combustible gas. Let The condition indicating that the deposit is expected to adhere to the part of the deposition conditions is that the detection value of the temperature sensor provided on the upper portion of the combustion chamber 32 or the detection value of the temperature sensor provided on the boundary 35 is It is determined that the condition is established when the temperature is equal to or lower than a preset reference temperature (melting temperature of ash) or when the basicity of the combustible gas flowing into the combustion chamber 32 from the inlet 30a is changed. Moreover, the conditions which show that the deposit | attachment adhered to the said site | part among the said adhesion conditions are when the adhesion of slag to the upper part of the combustion chamber 32 is confirmed visually, or the outflow of slag from the tap 30b. It is determined that it is established when a decrease in the amount is confirmed. When this adhesion condition is satisfied, the fuel f and the burner air a1 are supplied to the burner 42 in order to raise the temperature in the combustion chamber 32 to a temperature at which the slag melts. Here, burner air a1 having an air ratio of 1.0 to 1.3 is supplied so that the fuel f is completely combusted. In this state, the combustible gas flowing in from the inlet 30a burns while forming a swirling flow in the combustion chamber 32. Thereby, the temperature in the combustion chamber 32 rises to about 1300 ° C. The ash in the combustible gas is melted by this heat and separated from the combustible gas. The molten slag formed by melting the ash flows down the inner surface of the side wall 33 of the combustion chamber 32 and the upper surface of the bottom wall 37 of the slag discharge chamber 36 and is discharged from the outlet 30b. The exhaust gas after burning in the combustion chamber 32 is discharged downstream through the gas discharge chamber 38.

  In the present embodiment, the combustion air a2 that assists the combustion of the combustible gas is also supplied during the normal operation. The supply of the combustion air a <b> 2 is performed in the duct 50. Specifically, the combustion air a <b> 2 is supplied so that the total air ratio (the air ratio to the combustible gas and the fuel f) at the lower part (boundary 35) of the combustion chamber 32 is about 1.0.

  By continuously performing the above-mentioned normal operation in the swirling flow melting furnace 20, the adhering substance C (FIG. 2) such as slag having a high melting temperature formed by cooling the molten slag on the bottom wall 39 of the gas discharge chamber 38. 2) may adhere. If the deposit C adheres to the bottom wall 39 of the gas discharge chamber 38, the flow path of the exhaust gas in the gas discharge chamber 38 becomes narrow, so that the pressure loss generated when the exhaust gas passes through the gas discharge chamber 38 increases. . For this reason, in this embodiment, when the deposit | attachment C adheres, the driving | operation at the time of removing the said deposit | attachment C is made. Specifically, in this operation, when the deposit C adheres to the bottom wall 39 of the gas discharge chamber 38, the fuel f and the air ratio to the fuel f are larger than the supply amount of the fuel f in the normal operation. By supplying the burner air a1 with an amount larger than the air ratio (1.0 to 1.3) during normal operation (for example, 1.5 or more) to the burner 42, it is shown in FIG. As described above, the flame 44 is extended downward so that the lower end of the flame 44 reaches the slag discharge chamber 36, and the deposit C is melted. At this time, the combustion air a2 is supplied in such a manner that the total air ratio in the lower part (boundary 35) of the combustion chamber 32 is the same as that in the normal operation (about 1.0). It is done while adjusting.

  As described above, in the operation method of the gasification melting furnace of the present embodiment, the burner 42 is operated at an appropriate air ratio (for example, 1.0 to 1.3) when the adhesion condition is satisfied in the normal operation process. Thus, the combustible gas can be burned effectively and the ash can be melted. On the other hand, when the deposit C adheres to the bottom wall 39 of the gas discharge chamber 38, the fuel in the normal operation process is temporarily A burner 42 is supplied with a quantity of fuel f that is larger than the supply quantity of f and the air ratio a to the fuel f is larger than that in the normal operation process (for example, 1.5 or more), and is supplied to the burner 42. By extending 44 downward, the gas discharge chamber 38 can be maintained at a higher temperature. Specifically, the position of the lower end (tip) of the flame 44 in the operation process at the time of adhesion is maintained such that the air ratio to the normal operation process and the fuel f is the same (1.0 to 1.3) as that in the normal operation process. In addition, when the fuel f is burned in the normal increase state in which the supply amount of the fuel f and the supply amount of the burner air a1 are increased from those in the normal operation process, the fuel discharge chamber 38 is closer to that. Therefore, it is possible to maintain the gas discharge chamber 38 at a higher temperature when the burner 42 is operated at the air ratio in the operation process at the time of attachment than when the burner 42 is continuously operated at the air ratio in the normal operation process and the normal increase state. Can do. Therefore, in this operation method, when the deposit C adheres to the bottom wall 39 of the gas discharge chamber 38 while burning the combustible gas and melting the ash in the normal operation process, the fuel f is temporarily supplied. The gas discharge chamber is maintained at a higher temperature by supplying the burner 42 with an amount of fuel f that is greater than the amount of fuel f and the air ratio to the fuel f that is greater than that in the normal operation process. The amount of use can be reduced.

  In the above embodiment, the supply amount of the combustion air a <b> 2 is adjusted so that the total air ratio at the lower part (boundary 35) of the combustion chamber 32 is constant in the normal operation process and the attachment operation process. For this reason, since the combustible gas and the fuel f are effectively burned in the combustion chamber 32, the inside of the combustion chamber 32 can be effectively maintained at a high temperature in both the normal operation step and the attachment operation step. Specifically, in the operation process at the time of attachment, the supply amount of the combustion air a2 is adjusted according to the supply amount of the burner air a1 so that the total air ratio is the same as that in the normal operation process.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, although the example in which the combustion air a <b> 2 is supplied into the duct 50 has been shown in the above embodiment, the combustion air a <b> 2 may be supplied directly into the combustion chamber 32 through the side wall 33 and the top wall 34. .

  Further, in the above-described operation process at the time of attachment, burner air a1 may be supplied in such an amount that the lower end of the flame 44 reaches the outlet 30b or the gas discharge chamber 38.

DESCRIPTION OF SYMBOLS 10 Fluidized bed type gasification furnace 12 Furnace main body 14 Fluidized bed 20 Swirling flow melting furnace 30 Furnace main body 30a Inlet 30b Outlet 32 Combustion chamber 34 Top wall 36 Slag discharge chamber 38 Gas discharge chamber 39 Bottom wall 42 Burner 44 Flame a1 Burner air a2 Combustion air f Fuel C Deposit

Claims (4)

A gasification melting furnace operating method comprising a gasification furnace and a melting furnace,
As the gasification furnace, a gasification furnace preparation step of preparing what can generate a combustible gas by heating waste,
As the melting furnace, a combustion chamber having an inflow port for the combustible gas, burning the combustible gas, extending obliquely downward from a lower portion of the combustion chamber, and an ash content contained in the combustible gas in the combustion chamber A slag discharge chamber that leads molten slag formed by melting to a tap outlet, and a bottom wall extending from the tap outlet toward the opposite side of the slag discharge chamber, and burned in the combustion chamber A melting furnace preparation step of preparing a furnace body having a gas discharge chamber for discharging the exhaust gas after, and a burner provided on the top wall of the combustion chamber so that the flame extends downward,
Fuel and burner air are supplied to the burner when an adhering condition indicating that an adhering substance has adhered or is expected to adhere to at least a portion of the furnace body upstream of the tap hole is expected. A normal operation step of burning the combustible gas flowing into the combustion chamber from the inlet by melting and melting the ash contained in the combustible gas;
When the deposit adheres on the bottom wall of the gas discharge chamber, the ratio of fuel to the amount of fuel supplied in the normal operation process is larger than that in the normal operation process. An operation method of the gasification melting furnace, comprising: an operation step at the time of adhesion in which the flame is extended downward by supplying an amount of the burner air to the burner to melt the deposit. In the operation method of the gasification melting furnace according to claim 1,
In the attaching operation step, gasification is performed to supply the burner air in such an amount that the air ratio is larger than the air ratio to the fuel in the normal operation step and the lower end of the flame reaches the slag discharge chamber. How to operate the melting furnace. In the operation method of the gasification melting furnace according to claim 2,
In the normal operation step, the burner air is supplied in an amount such that an air ratio to the fuel is 1.0 to 1.3,
The operation method of the gasification melting furnace which supplies the said air for burners of the quantity in which the air ratio with respect to the said fuel becomes 1.5 or more at the said operation process at the time of adhesion. In the operation method of the gasification melting furnace in any one of Claims 1 thru | or 3,
In the normal operation step and the adhesion operation step, combustion air is supplied to the combustion chamber to assist combustion of the combustible gas, and the supply is performed by the combustible gas and the lower portion of the combustion chamber. A method for operating a gasification melting furnace, wherein the supply amount of the combustion air is adjusted so that a total air ratio to fuel is constant.

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