JP7054094B2 - Combustion control method, waste incinerator power generation equipment - Google Patents

Description

The present invention relates to a method for controlling combustion of a waste incinerator and a waste incinerator power generation facility in which a waste heat boiler is attached to the waste incinerator.

An incinerator for treating waste discharged from social life produces exhaust gas with enormous heat energy by incinerating the waste. Therefore, the structure of the incineration facility is generally equipped with a boiler (waste heat boiler) that uses the waste heat of the exhaust gas as a heat source.

In this type of incinerator, combustion control is performed to keep the amount of steam generated by the boiler constant by adjusting the amount of waste burned according to the amount of waste supplied, feed rate, amount of primary combustion air and its distribution, etc. Is often done.

However, the properties of the waste supplied into the furnace (fuel composition, calorific value, etc.) are not constant, so even if these are controlled, it is caused by rapid combustion, flame retardancy, or rapid combustion of the waste. Subsequent shortage of residual waste in the furnace may occur, and it may be difficult to maintain a constant amount of evaporation.

In view of this point, in Patent Document 1 below, the evaporation amount of boiler water and the amount of waste on the combustion grate are periodically measured, and the waste supply amount and the dry grate speed are measured based on the waste amount and the evaporation amount. We are proposing a technology to control.

Japanese Unexamined Patent Publication No. 09-273731

The technique disclosed in Patent Document 1 is based on the amount of evaporation of boiler water as the basis of combustion control.
However, the incinerator and boiler processes are roughly divided into the former combustion system and the latter boiler system (heat exchange between exhaust gas and boiler water). Since the time constant of the boiler system is much longer than that of the combustion system, it becomes difficult to respond to sudden changes in the combustion state due to changes in the properties of waste when controlling only by the amount of evaporation of boiler water. , Will cause fluctuations in the amount of evaporation of boiler water.

Further, in the conventional horizontal stoker furnace, since the combustion state is different in each process of drying, combustion, and post-combustion, complicated control such as adjustment of the grate speed and the input position and amount of the primary combustion air is required.

On the other hand, in the vertical waste incinerator, unlike the above horizontal stoker furnace, waste is stacked vertically and a certain amount of primary combustion air is supplied from the lower part of the sedimentary layer at an air ratio of 0.2 to 0.8, and the lower part of the sedimentary layer. It is possible to keep the amount of combustion constant. Therefore, it is possible to suppress fluctuations in the amount of boiler evaporation without performing complicated control as in a horizontal stoker furnace, and in addition, the amount of heat stored on the grate is larger than that of a horizontal stoker furnace, so stability is achieved. Is also excellent. However, even if the combustion amount is constant, the composition of the pyrolysis gas generated varies depending on the composition of the waste, and when the furnace outlet temperature is controlled, the amount of exhaust gas fluctuates and the fluctuation range of the evaporation amount is about ± 10%. It was difficult to keep it within the recently required ± 5% (preferably ± 3%).

The present invention has been developed in view of the above technical problems, and is a novel combustion control method capable of suitably controlling the amount of evaporation of boiler water during operation of a waste incinerator with a waste heat boiler, and waste. The purpose is to provide incinerator power generation equipment.

The combustion control method of the present invention for solving the above technical problems includes a primary combustion stroke in which the waste is burned while supplying the primary combustion air from the lower part of the sedimentary layer formed by the waste put into the furnace. Utilizing the secondary combustion stroke in which the combustible gas generated by the execution of the primary combustion stroke is burned while supplying the secondary combustion air, and the waste heat of the exhaust gas generated by the execution of the primary combustion stroke and the secondary combustion stroke. It is a combustion control method in a waste incinerator power generation facility that incinerates waste and generates power by executing the boiler power generation process that generates boiler water. Prior to the feedback control that changes the supply amount of the secondary combustion air, the preceding element control that changes the supply amount of the secondary combustion air according to the change in the calorific value of the exhaust gas is performed (hereinafter, "the present invention"). Control method ").

In the control method of the present invention, in the preceding element control, the heat amount of the exhaust gas is controlled by the supply amount of the secondary combustion air, but it is finely controlled by the supply amount of the cooling water in the furnace so that the temperature in the furnace falls within the set range. It is a preferable embodiment to make adjustments.

In the control method of the present invention, in the feedback control, the calorific value of the exhaust gas is determined by the preceding element control, and then the evaporation amount of the boiler water is determined, and fine adjustment is performed according to the supply amount of the secondary combustion air.

In the control method of the present invention, in the preceding element control, it is preferable to further keep the temperature inside the furnace within the set range and change the supply amount of the primary combustion air according to the amount of heat of the exhaust gas.

The waste incinerator power generation facility of the present invention for solving the above technical problems burns and generates waste while supplying primary combustion air from the lower part of the sedimentary layer formed by the waste put into the furnace. Waste that includes a waste incinerator that burns combustible gas while supplying secondary combustion air, and a waste heat boiler that uses the waste heat of exhaust gas generated by the operation of the waste incinerator to generate boiler power. An incinerator power generation facility, an exhaust gas temperature measuring device for measuring the furnace outlet temperature of exhaust gas, an exhaust gas flow rate measuring device for measuring the flow rate of exhaust gas, and a steam amount for measuring the evaporation amount of boiler water. A measuring instrument is provided, and further, a feedback control that changes the supply amount of secondary combustion air according to a change in the amount of evaporation of boiler water measured by the steam amount measuring device, and the exhaust gas temperature measuring device. Preceding element control that changes the supply amount of secondary combustion air according to the change in the amount of heat of the exhaust gas expected due to the change in the temperature of the exhaust gas measured by the above-mentioned exhaust gas flow meter and the change in the flow rate of the exhaust gas measured by the exhaust gas flow rate measuring device. It is characterized by being provided with a control device (hereinafter, referred to as "the power generation facility of the present invention").

In the power generation facility of the present invention, a dust collector for removing dust contained in the exhaust gas is provided downstream of the flue from the waste heat boiler, and the flow rate of the exhaust gas passing through the dust collector is measured. In order to measure, it is preferable that the exhaust gas flow rate measuring device is provided downstream of the dust collector.

According to the present invention, it is possible to control the amount of evaporation of boiler water during operation of a waste incinerator with a waste heat boiler, and it is possible to obtain a stable amount of power generation.

FIG. 1 is a schematic view showing an embodiment of the power generation facility of the present invention. FIG. 2 is a block diagram showing a control device for the power generation facility of the present invention. FIG. 3 is a control system block diagram showing a control concept of the control device. FIG. 4 is a flowchart showing a control procedure of feedback control by the control device. FIG. 5 is a flowchart showing a control procedure for controlling the preceding element by the control device. FIG. 6 is a schematic view showing another embodiment of the power generation facility of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments.

[Power generation equipment of the present invention (1)]
FIG. 1 shows an embodiment of the power generation facility 1 of the present invention. The power generation facility 1 of the present invention includes a "waste incinerator (2)" and a "waste heat boiler (3)", and further includes a "control device (4)" shown in FIG.

<Waste incinerator 2>
The waste incinerator 2 in the present embodiment burns the waste W while supplying "primary combustion air" from the lower part of the sedimentary layer W1 formed by the waste W put into the furnace 21, and the generated combustible. It is a so-called "vertical waste incinerator" that employs a combustion method that burns while supplying "secondary combustion air" for sex gas. The "exhaust gas" generated by the combustion treatment is discharged through the furnace outlet 22. Further, the waste incinerator 2 employs a mechanism that can suppress the combustion state in the furnace 21 by spraying "cooling water in the furnace" and thereby prevent the temperature of the furnace 21 from becoming high.

-Primary combustion air-
In the present embodiment, the primary combustion air is supplied through the primary combustion air supply line AL1. The primary combustion air supply line AL1 is a pipe in which one end is connected to the primary air pushing fan F1 and the other end is arranged so as to reach the lower part of the furnace 21 of the waste incinerator 2. A primary valve (damper) V1 that determines the amount of primary combustion air supplied is provided.

-Secondary combustion air-
In the present embodiment, the secondary combustion air is supplied through the secondary combustion air supply line AL2. The secondary combustion air supply line AL2 is a pipe in which one end is connected to the secondary air pushing fan F2 and the other end is arranged so as to reach the inside of the furnace 21 of the waste incinerator 2. Is provided with a secondary valve (damper) V2 that determines the supply amount of secondary combustion air.

-Exhaust gas-
In the present embodiment, the combustible gas generated by the combustion of the waste W is first burned in the main combustion chamber 211, and then the combustible gas that has passed through the rectifying device 23 is completely burned in the recombustion chamber 212. There is. The exhaust gas generated by the combustion treatment passes through the furnace outlet 22 and is transported along the exhaust gas line GL. In the present embodiment, after the exhaust gas is supplied to the waste heat boiler 3, the economizer 5 that preheats the water supply by using the residual heat of the exhaust gas and the dust collector (bug filter) 6 that removes the dust contained in the exhaust gas pass in order. The exhaust gas line GL is constructed so that the exhaust gas is discharged to the atmosphere through the chimney 7. Further, the flow of the exhaust gas is formed by a gas attracting fan F3 provided between the dust collector 6 and the chimney 7. In the present embodiment, the exhaust gas temperature measuring device (24) for measuring the temperature of the exhaust gas passing through the furnace outlet 22 is provided in the furnace outlet 22, and the flow rate of the exhaust gas passing through the furnace outlet 22 is provided. The exhaust gas line GL is provided with an "exhaust gas flow rate measuring device (25)" for measuring the temperature.

-Cooling water in the furnace-
In the present embodiment, the cooling water in the furnace is supplied into the furnace 21 through the cooling water supply line WL. The cooling water supply line WL is a pipe arranged so that one end is connected to a water supply source (not shown) and the other end reaches the inside of the furnace 21 of the waste incinerator 2, and is in the middle of the pipeline. A cooling water valve V3 that determines the amount of cooling water supplied in the furnace is provided.

<Waste heat boiler 3>
The waste heat boiler 3 plays a role of generating boiler power by utilizing the waste heat of the exhaust gas generated by the operation of the waste incinerator 2. In the present embodiment, the steam generated by the evaporation of the boiler water is transported through the steam line SL. In the present embodiment, the steam line SL is provided with a "steam amount measuring device (31)" for measuring the amount of evaporation of boiler water.

<Control device 4>
As described above, the change in the evaporation amount of the boiler water is measured by the steam amount measuring device 31. Further, the calorific value of the exhaust gas is expected according to the change in the temperature of the exhaust gas and the change in the flow rate of the exhaust gas measured by the exhaust gas temperature measuring device 24 and the exhaust gas flow rate measuring device 25. As shown in FIG. 2, the values measured by each measuring instrument (31, 24, 25) are transmitted to the control device 4. The control device 4 compares the measured evaporation amount of boiler water and the expected heat amount of exhaust gas with the set value stored in advance in the storage means 41 in the calculation means 42, and corresponds to the measured value. The command is given to the secondary valve V2 and the cooling water valve V3 through the control means 43. Then, as shown in FIG. 3, in the control by the control device 4, "preceding element control" and "feedback control" are performed.

-Preceding element control-
In the preceding element control, the supply amount of the secondary combustion air is changed according to the change in the calorific value of the exhaust gas expected from the change in the temperature of the exhaust gas and the flow rate of the exhaust gas. In the present embodiment, the preceding element control is executed by the control procedure shown in the flowchart of FIG.

In the control procedure shown in this flowchart, first, after the operation of the waste incinerator 2 is started (S1) and after a certain period of time has elapsed (S2), the temperature of the exhaust gas is determined by the exhaust gas temperature measuring device 24 and the exhaust gas flow rate measuring device 25. The flow chart is measured (S7, S8). The calculation means 42 predicts the calorific value of the exhaust gas from the measured temperature and flow rate of the exhaust gas, and sets the set value (in this case, the allowable range of the calorific value of the exhaust gas preset) and the predicted value stored in the storage means 41. The calorific value of the current exhaust gas is evaluated by comparing with (S9), and the operation to be applied to the secondary valve V2 is determined (S10). The control means 43 commands the determined operation to the secondary valve V2 (S11). Immediately after the operation command (S6), the following steps of measuring the temperature and flow rate of the exhaust gas (S7, S8) are repeated. In this embodiment, the operation given to the secondary valve V2 in the preceding element control is determined under the conditions shown in Table 1 below.

-Feedback control-
On the other hand, in the feedback control, the supply amount of the secondary combustion air is changed according to the change in the evaporation amount of the boiler water to be controlled, so that the evaporation amount of the boiler water is controlled to be within the set value. In the present embodiment, the feedback control is executed by the control procedure shown in the flowchart of FIG.

In the control procedure shown in this flowchart, first, after the operation of the waste incinerator 2 is started (S1) and after a certain period of time has elapsed (S2), the evaporation amount of the boiler water is measured by the steam amount measuring device 31 (S3). ). The calculation means 42 evaluates the current evaporation amount by comparing the preset set value (in this case, the allowable range of the evaporation amount of the boiler water) stored in the storage means 41 with the actually measured value (the calculation means 42). S4), the operation to be applied to the secondary valve V2 is determined (S5). The control means 43 commands the determined operation to the secondary valve V2 (S6). After the operation command (S6), if a certain period of time elapses (S2), the following steps of evaporation amount measurement (S3) are repeated. In this embodiment, the operation given to the secondary valve V2 in the feedback control is determined under the conditions shown in Table 2 below.

[Control method of the present invention]
The power generation facility 1 of the present invention having the above configuration changes the calorific value of the exhaust gas prior to the feedback control in which the supply amount of the secondary combustion air or the supply amount of the cooling water in the furnace is changed according to the change in the evaporation amount of the boiler water. It is constructed to execute the control method of the present invention that controls the preceding element that changes the supply amount of the secondary combustion air according to the above.

By the feedback control, "measurement of boiler water evaporation amount"-> "control calculation"-> "operation amount (opening of the secondary valve V2) output"-> "change in boiler water evaporation amount"-> "boiler water" By performing the closed loop control (see FIGS. 3 and 4) of "measurement of the amount of evaporation of the boiler water", the amount of evaporation of the boiler water to be controlled can be controlled.

However, in the feedback control, since the result after the output of the operation amount (change in the evaporation amount of boiler water) is fed back and then corrected, various disturbances that disturb the control (for example, changes in the properties of the input waste) are used. Even if a sudden change in the combustion state occurs), it can only be corrected after the effect appears as a change in the amount of evaporation of boiler water.

Regarding this point, in the control method of the present invention, prior to the feedback control, the secondary combustion air is changed according to the change of the heat amount of the exhaust gas (exhaust gas temperature × exhaust gas amount ≒ heat amount) derived from the temperature of the exhaust gas and the flow rate of the exhaust gas. Since the preceding element control that changes the supply amount of the exhaust gas is performed, it is possible to quickly respond to a sudden change in the combustion state due to a change in the properties of the waste.

That is, unlike the feedback control, the preceding element control does not have a closed loop in the signal flow, and "disturbance detection (change in exhaust gas temperature or exhaust gas flow rate)" → "control calculation" → "operation". It is a one-way control method called "quantity output" (see FIGS. 3 and 5). Therefore, if the preceding element control is performed prior to the feedback control, even if a disturbance that disturbs the feedback control occurs, the preceding element does not appear as a "change in the amount of evaporation of boiler water". By controlling, it is possible to perform a correction operation that eliminates the influence in advance.

From this, according to the present invention, it is possible to control the amount of evaporation of boiler water during operation of the waste incinerator 2 to which the waste heat boiler 3 is attached, and it is possible to obtain a stable power generation amount.

In the present embodiment, commands are given only to the secondary valve V2 at the same time for the preceding element control and the feedback control (see Table 2), but the operations in the preceding element control and the feedback control are described in the above two. A command may be given to the cooling water valve V3 in addition to the next valve V2. For example, when the temperature inside the furnace is higher than the set value (for example, 950 ° C), the supply amount of the cooling water in the furnace is increased, and when the temperature inside the furnace is lower than the set value (for example, 850 ° C), the cooling water in the furnace is increased. By reducing the supply amount, it is possible to effectively prevent the generation of dioxin and the production of clinker.

Further, in the present embodiment, the operations in the feedback control and the preceding element control are determined under the conditions shown in Tables 1 and 2, but the operations in the feedback control and the preceding element control are not necessarily related. It is not determined only by the conditions, but may be appropriately determined according to the incinerator capacity of the waste incinerator 2, the amount of boiler water evaporation required for the waste heat boiler 3, the allowable fluctuation range of the amount of evaporation, and the like. ..

In the present embodiment, a vertical waste incinerator is used as the waste incinerator 2, but the control method of the present invention is not limited to the control of the vertical waste incinerator. However, prior element control that changes the supply amount of secondary combustion air according to the change in the calorific value of the exhaust gas precedes the feedback control that changes the supply amount of the secondary combustion air according to the change in the evaporation amount of the boiler is vertical waste. It makes the best use of the characteristics of the incinerator.

By the way, in the present embodiment, the supply amount of the primary combustion air is not changed in the feedback control and the preceding element control, but in the feedback control, the supply amount of the primary combustion air can be further changed. In the preceding element control, it is also possible to change the supply amount of the primary combustion air according to the change in the temperature of the exhaust gas or the flow rate of the exhaust gas. The change in the supply amount of the primary combustion air in the feedback control and the preceding element control can be performed by increasing or decreasing the opening degree of the primary valve (damper) V1 provided in the primary combustion air supply line AL1. It is preferable that the increase / decrease of the primary combustion air is performed according to the increase / decrease of the secondary combustion air.

Further, in the present embodiment, in order to improve the response of the preceding element control, the exhaust gas temperature measuring device 24 is provided at the furnace outlet 22, while the exhaust gas flow rate measuring device 25 is provided upstream of the exhaust gas line GL. However, since the exhaust gas flowing upstream of the exhaust gas line GL contains a large amount of dust, the exhaust gas flow rate measuring device 25 is provided downstream of the dust collector 6 as shown in FIG. It is preferable to be able to measure the flow rate of the exhaust gas having a low dust content that has passed through the dust device 6.

It should be noted that the present invention can be carried out in various other forms without departing from its spirit or main characteristics. Therefore, the above embodiments are merely exemplary in all respects and should not be construed in a limited way. The scope of the present invention is shown by the scope of claims and is not bound by the text of the specification. Further, all modifications and modifications that fall within the equivalent scope of the claims are within the scope of the present invention.

INDUSTRIAL APPLICABILITY The present invention is suitably used as a control means for stabilizing the combustion state of a waste incinerator.

1 Power generation equipment of the present invention (waste incinerator power generation equipment)
2 Waste incinerator 21 Furnace 22 Furnace outlet 24 Exhaust gas temperature measuring device 25 Exhaust gas flow rate measuring device 3 Waste heat boiler 31 Steam amount measuring device 4 Control device 41 Storage means 42 Calculation means 43 Control means 5 Economizer 6 Dust collector 7 Chimney AL1 Primary Combustion air supply line AL2 Secondary combustion air supply line GL Exhaust gas line SL Steam line WL Cooling water supply line V1 Primary valve V2 Secondary valve V3 Cooling water valve W Waste W1 Deposit layer

Claims (6)

The primary combustion process in which the waste is burned while supplying the primary combustion air from the lower part of the sedimentary layer formed by the waste put into the furnace.
A secondary combustion stroke in which the combustible gas generated by the execution of the primary combustion stroke is burned while supplying secondary combustion air, and
A boiler power generation process that uses the waste heat of exhaust gas generated by the execution of the primary combustion stroke and the secondary combustion stroke to generate boiler power.
It is a combustion control method in a waste incinerator power generation facility that incinerates waste and generates electricity by executing.
Prior to feedback control that changes the supply amount of secondary combustion air according to the change in the evaporation amount of boiler water,
Preceding element control that changes the supply amount of secondary combustion air according to the change in the calorific value of the exhaust gas is performed.
In the feedback control,
If the amount of evaporation of boiler water is higher than the set value, the amount of secondary combustion air supplied will be reduced.
A combustion control method characterized by increasing the supply amount of secondary combustion air when the evaporation amount of boiler water is lower than a set value . In the combustion control method according to claim 1 ,
In the preceding element control,
If the temperature inside the furnace is higher than the set range, the supply amount of cooling water in the furnace is increased.
A combustion control method that reduces the supply of cooling water in the furnace when the temperature inside the furnace is lower than the set range. In the combustion control method according to claim 1 or 2 ,
In the feedback control,
Furthermore, a combustion control method that changes the supply amount of primary combustion air according to the change in the evaporation amount of boiler water. In the combustion control method according to any one of claims 1 to 3 ,
In the preceding element control,
Further, a combustion control method in which the supply amount of primary combustion air is changed according to a change in the temperature of the exhaust gas or the flow rate of the exhaust gas. A waste incinerator that burns waste while supplying primary combustion air from the lower part of the sedimentary layer formed by the waste input into the furnace, and also supplies secondary combustion air for the generated combustible gas. ,
A waste heat boiler that uses the waste heat of exhaust gas generated by the operation of the waste incinerator to generate electricity.
It is a waste incinerator power generation facility equipped with
An exhaust gas temperature measuring device for measuring the furnace outlet temperature of exhaust gas,
An exhaust gas flow rate measuring device for measuring the flow rate of exhaust gas,
A steam meter for measuring the amount of evaporation of boiler water,
Be prepared,
Further, when the evaporation amount of the boiler water measured by the steam amount measuring device is higher than the set value, the supply amount of the secondary combustion air is reduced, and when the evaporation amount of the boiler water is lower than the set value, the secondary combustion air is reduced. According to the feedback control that increases the supply amount of the exhaust gas, and the change in the amount of heat of the exhaust gas expected due to the change in the temperature of the exhaust gas measured by the exhaust gas temperature measuring device and the flow rate of the exhaust gas measured by the exhaust gas flow measuring device. Preceding element control that changes the supply amount of next combustion air,
A waste incinerator power generation facility characterized by being equipped with a control device for performing the above. In the waste incinerator power generation facility according to claim 5 .
A dust collector for removing dust contained in the exhaust gas is provided downstream of the flue from the waste heat boiler.
A waste incinerator power generation facility in which the exhaust gas flow rate measuring device is provided downstream of the dust collecting device in order to measure the flow rate of the exhaust gas that has passed through the dust collecting device.

Images