JPH10299424A - Steam temperature controlling method for refuse incinerating power plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extremely reduce total sprayed amount used for controlling steam temperature to improve plant thermal efficiency, by controlling a desuperheater of each unit so as to restrain temperature difference of steam generated form plural units which have a refuse incinerator and a waste heat boiler within tolerance. SOLUTION: In a plant which has plural units 500, 600... having a refuse incinerator 1 and a waste heat boiler 2 and drives a power generator 13 via a steam turbine 6 using generated steam, a steam temperature controller 2000 includes a boiler outlet steam temperature adjusting means 200 for restraining temperature difference of steam generated form plural units within tolerance. In addition, the controller 2000 includes a main steam temperature adjusting means 300 for controlling main steam temperature to a target value. On the basis of output signals from the adjusting means 200, 300, a sprayed amount controller 400 sets a target spayed amount, controls flow control valves 43-45 according to the set value, and adjusts sprayed amount corresponding to desuperheaters 37-39.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a steam temperature of a refuse incineration power plant.

[0002]

2. Description of the Related Art In a multi-unit refuse incineration power plant, steam generated from a waste heat boiler of each unit is collectively converted into main steam by an accumulator, and the steam is guided to a single steam turbine to generate power. Here, it is necessary for control to keep the variation of the steam temperature generated by the waste heat boiler below a certain level in order to keep the thermal stress generated at the inlet of the accumulator below the allowable value, and the fluctuation range of the main steam temperature is also constant. It is to keep below. Therefore, in the conventional method, in order to keep the temperature of the steam generated from each waste heat boiler at a constant value corresponding to the target main steam temperature, the spray amount of the desuperheater between the evaporator and the superheater is adjusted. It was controlled individually.

However, the calorific value of refuse in a refuse incinerator, which is a heat source of a waste heat boiler, is 20% to 30% even in a steady operation.
And the generated steam temperature also fluctuates greatly. For this reason, a large-capacity temperature reducer was installed for the power generation output as compared with a commercial power plant, and temperature control by a large amount of spray was inevitable. Therefore, there is an economic problem that not only the equipment cost is increased due to the installation of the large-capacity temperature reducer but also the operation cost is increased because the plant is operated in a state where the thermal efficiency is low due to the large amount of spray.

[0004]

The problem to be solved by the present invention is to control the main steam temperature stably while keeping the temperature difference of steam generated from a plurality of units within an allowable value, and to use the steam for controlling the steam temperature. The aim is to improve the thermal efficiency of the plant by minimizing the total amount of spraying.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention has devised a steam temperature control method for positively utilizing a variation in steam temperature between units. In other words, even if the steam temperature from each unit has a deviation from the target temperature, and even if there is a variation, the individual temperature is not directly controlled and the effect of canceling the steam temperature between the units is used. Therefore, in the present invention, the main purpose is to control the temperature difference between the steam generated from a plurality of units within a permissible value and to control the main steam temperature to a target value. A main steam temperature adjusting means and a spray amount controlling means for controlling a spray amount by adjusting a valve opening of a temperature reducing device in response to a target spray amount set by these two adjusting means.

Since the main purpose of the boiler outlet steam temperature adjusting means is to keep the temperature difference of steam generated from a plurality of units within an allowable value as described above, the maximum temperature and the minimum temperature of the steam generated from the plurality of units are determined. It is constantly monitored and is considered only for the unit requiring the minimum spray amount adjustment necessary to keep this temperature difference within the allowable value, that is, the unit showing the above-mentioned maximum or minimum temperature.

If the temperature of the main steam into which the steam from each unit is integrated deviates from the target value,
In accordance with the deviation, the spray amount is adjusted by the main steam temperature adjusting means with respect to the unit indicating the highest temperature or the lowest temperature.

In practice, the target spray amount is determined from the above two means, and is set in the spray amount control means. By adjusting the valve opening of the temperature reducer in response to the target spray amount, the variation in the steam temperature at the boiler outlet falls within an allowable value, and the main steam temperature is controlled stably. as a result,
Compared with the conventional system in which individual control was performed, the capacity of each desuperheater can be greatly reduced, and the total spray amount can be minimized, so that the plant can be operated with high thermal efficiency.

[0009]

FIG. 1 shows the overall configuration of a refuse incineration power plant 1000 to be controlled, a process state input means 100 as a main means of a steam temperature control means 2000 according to an embodiment of the present invention, and a boiler outlet steam. Temperature adjusting means 20
0, main steam temperature adjusting means 300, spray amount control means 4
00 and input / output signals. Here, the waste incineration power plant 1000 includes No. 1 unit 500, No. 2 unit 600,...
00, and generally n = about 2-5.

Each unit of the plant comprises a stoker-type incinerator 1 and a waste heat boiler 2 for recovering thermal energy from its combustion gas and generating steam during normal operation.
Superheated steams 3, 4, and 5 generated from a plurality of units are collectively guided to one steam turbine 6 to generate power. In each unit, refuse introduced into the incinerator 1 by the pusher 7 is burned by the combustion air 9 sent by the blower 8, and the heat energy of the high-temperature combustion gas is converted into steam generated by the waste heat boiler 5. Collected. Superheated steams 3, 4, and 5 from each waste heat boiler are sent to an accumulator 10 and merged into a main steam 11, which is introduced into a steam turbine 6 through a control valve 12, and is generated by a generator 13 connected thereto. Output 14 is used. Exhaust gas 15 after driving the steam turbine 6 is condensed by a condenser 16 and sent to a deaerator 17, where water pumps 18, 19,
At 20, it is sent to the economizers 21, 22 and 23 of the waste heat boiler. The water supplied by the economizer is supplied to the drum 24,
The evaporators 27, 28, and 29 evaporate via 25 and 26, and are further superheated by superheaters 30, 31, and 32 to become superheated steam 3, 4, and 5. Part of the superheated steam is sent to the deaerator 17 via the accumulator 10 and is used as the heating steam 33 for deaeration.

The plant 1000 has a thermometer 34 for measuring the superheated steam temperature T _SH (1), T _SH (2), T _SH (n) at the boiler outlet as a process state required for steam temperature control. , 35, 36, flow meters 40, 41, 42 for measuring the spray amount to the superheater 37, 38, 39 for controlling the superheated steam temperature, the flow regulating valves 43, 44, 45 for adjusting the spray amount, And a thermometer 46 for measuring the main steam temperature T _MS .

Next, a conventional steam temperature control method and its problems will be described with reference to FIG. In this figure,
For convenience of explanation, a case where n = 3, that is, a case where the plant is composed of three units is shown, but the following description does not lose generality. In the conventional method, in order to control the fluctuating superheated steam temperature T _SH (1), T _SH (2), T _SH (3) to the target main steam temperature T _MSR , each of the desuperheaters has a superheated steam temperature deviation. Operate individually according to the spray amount G
_SP (1), G _SP (2), and G _SP (3) are injected. As a result, a large amount of spray G _SPT is required as a whole regardless of whether the main steam temperature is equal to or higher than the target value.
The reason is that the variation of the temperature of each superheated steam is suppressed by a sufficient spray amount by individual control. In other words, it is necessary to have a desuperheater capacity capable of individually controlling even superheated steam whose temperature should be offset by merging with the accumulator 10, and taking into account both polarities of the temperature deviation, the operating reference point of the spray flow rate. Is also set higher. When the spray amount is large as described above, extra fuel is required, and as a result, the plant is operated with low thermal efficiency. Furthermore, the capacity of the desuperheater must be large enough for individual control, and the equipment cost will also increase.

FIG. 3 shows a detailed functional block and processing procedure of the steam temperature control means 2000 of the present invention for solving such a problem. The present steam temperature control means 2000 further comprises a process state input means 100, a boiler outlet steam temperature adjustment means 200, a main steam temperature adjustment means 300, and a spray amount control means 400. The process state input means 100 outputs the superheated steam temperature T _SH (1), T _SH (2),... T _SH (n), the spray amount G _SP (1), G _SP (2),... G _SP (n) and the main steam temperature T _MS are input, and the boiler outlet steam temperature adjusting means 20 is inputted.
It works to transfer to 0. Hereinafter, functions and processing procedures of each means will be specifically described. The boiler outlet steam temperature adjusting means 200 determines the highest temperature T _SH (m) (assuming that the superheated steam from the No. m unit was the highest temperature) and the lowest temperature T from the input n superheated steam temperatures.
A maximum / minimum temperature extracting means 51 for extracting _SH (k) (assuming that the superheated steam from the No. k unit has the lowest temperature), and a maximum temperature difference calculating means 52 for obtaining a maximum temperature difference ΔT _SH therefrom. The maximum temperature difference ΔT _SH obtained on the temperature difference margin ratio calculating means 53 for calculating the temperature difference margin ratio α _{SH based} on the allowable temperature difference ΔT _SHL corresponding to the maximum temperature difference ΔT _SH is the allowable temperature difference. Allowable temperature difference determination means 54 for determining whether or not ΔT _SHL is satisfied. If this is the case, whether or not steam temperature T _SH (m) indicating the maximum value is equal to or lower than allowable upper limit temperature T _SHL. The upper limit temperature determining means 55 for determining whether the target spray amount is not corrected when the determination result is equal to or lower than the allowable upper limit temperature T _SHL but is equal to or higher than T _SHL if the determination result is equal to or higher than T _SHL. .m target spray amount G _SPR (m) The according to the temperature difference margin alpha _SH upward revision maximum temperature corresponding target spray amount calculating means 56 for achieving cooling by, if the result of the determination in the allowable temperature difference determination means 54 does not satisfy the allowable temperature difference [Delta] T _SHL Is an upper limit temperature determining means 5 for determining whether the maximum steam temperature T _SH (m) is equal to or lower than the allowable upper limit temperature T _SHL.
7. If the determination result is equal to or lower than the allowable upper limit temperature T _SHL , the spray amount G of the No. k unit indicating the lowest temperature
Spray amount determining means 58 for determining whether or not _SP (k) is not zero. If spray amount G _SP (k) is not zero, target spray amount G _SPR (k) of No. k unit is set to a temperature difference margin. The target spray amount calculating means 59 corresponding to the lowest temperature for raising the temperature by correcting downward according to the rate _αSH, and the maximum steam temperature T by the upper limit temperature determining means 57.
Similarly, when _SH (m) is determined to be equal to or higher than the permissible upper limit temperature T _SHL or when the spray amount determining means 58 determines that the spray amount G _SP (k) of the No. k unit is zero, the maximum value is also obtained. No. in the temperature corresponding target spray amount calculation means 56.
The target spray amount G _SPR (m) of the m unit is corrected upward in accordance with the temperature difference margin ratio α _{SH so as} to lower the temperature. As described above, the boiler outlet steam temperature adjusting means 200 determines that the maximum temperature difference ΔT _SH between the superheated steam from a plurality of units flowing into the accumulator 10 is equal to the allowable temperature difference ΔT
For _SHL below the allowable upper limit temperature T target spray amount if no unit above the _SHL is without modifying anything, the maximum temperature difference [Delta] T _SH is the allowable temperature difference [Delta] T _SHL or become above or the allowable upper limit temperature T _SHL unit Correct the target spray amount only when there is.

The main steam temperature adjusting means 300 _controls the main steam temperature deviation (T _MS -T _MSR ) (T _MSR is the target main steam temperature) with respect to the allowable deviation (T _MSL -T _MSR ) (T _MSL is the allowable upper limit temperature). Main steam temperature deviation rate calculating means 61 for obtaining the main steam temperature deviation rate β _MS which is a ratio, and target temperature determining means 6 for determining whether or not the main steam temperature is equal to or lower than the target temperature T _MSR.
2. When the temperature is equal to or lower than the target temperature T _MSR, the target spray amount G _SPR (k) of the No. k unit is corrected downward in accordance with the main steam temperature deviation rate β _MS so that the target spray corresponding to the minimum temperature is achieved. Amount calculation means 63, conversely, if it is higher than the target temperature T _MSR , the target spray amount G _SPR (m) of the No.m unit
Is corrected upward in accordance with the main steam temperature deviation rate β _MS to reduce the temperature, thereby forming a target spray amount calculating means 64 corresponding to the maximum temperature. Therefore, the main steam temperature adjusting means 300 sets the target spray amount to be corrected only for the unit in which the superheated steam temperature has the highest value or the lowest value according to the magnitude of the main steam temperature deviation.

The spray amount control means 400 is a control loop for controlling the spray amount of each unit, that is, No.
1 unit spray control loop 70, No. 2 unit spray control loop 80,... No. n unit spray control loop 90, and these are corrected by the boiler outlet steam temperature adjusting means 200 and the main steam temperature adjusting means 300. Target spray amounts G _SPR (1), G _SPR (2),... G including the target spray amounts G _SPR (m) and G _SPR (k)
Target spray amount setting means 6 for setting _SPR (n)
5, each unit spray control loop 70, 8
90 is a deviation ΔG between the target spray amount and the actual measured value G _SP (1), G _SP (2),... G _SP (n).
_SP (1), ΔG _SP (2),... Deviation calculating means 71, 81, 91 for obtaining ΔG _SP (n), a flow rate adjusting valve 43 for spray amount adjustment according to the calculated deviation, 4
4, 45 target opening A _SPR (1), A _SPR (2), ... A
Valve opening adjusting means 72, 8 for determining _SPR (n)
2, 92, corresponding to the target opening degree, the flow regulating valves 43, 44,
Valve operating means 73, 83, 9 for operating the opening degree of 45
Consists of three. Here, the valve opening adjusting means 72, 82, 92
Then, the spray amount deviation ΔG _SP (1), ΔG _SP (2), ...
・ Target opening A by proportional integration operation in response to ΔG _SP (n)
_SPR (1), A _SPR (2),... A _SPR (n) are determined.

By repeating the processing procedure of each means in the steam temperature control means 2000 at a predetermined cycle, the temperature of the superheated steam generated from each unit is reduced.
The maximum temperature difference and the main steam temperature are monitored and controlled.

FIG. 4 shows the steam temperature control characteristics according to the present invention and the effects thereof. As can be seen from this figure, according to the present invention,
By monitoring and controlling the maximum temperature difference ΔT _SH , the individual spray amounts G _SP (1), G _SP (2),... G _SP (n) for each unit can be minimized.
_{The SPT is} also greatly reduced as compared with the conventional system shown in FIG. As described above, according to the present invention, the amount of spray can be significantly reduced, so that when the plant is operated with the same power generation output, the amount of waste input as fuel can be greatly reduced.

In the embodiment of the present invention, in the boiler outlet steam temperature adjusting means 200 and the main steam temperature adjusting means 300, the target spray amount is corrected only for the unit having the highest temperature or the lowest temperature. When the spray amount is at the limit value, that is, at the maximum value or the minimum value (zero) determined by the capacity of the desuperheater, it is possible to apply to the unit showing the next temperature without changing the gist of the present invention. .

Further, in the embodiment of the present invention, the method of adjusting the spray amount by paying attention to the superheated steam temperature generated from each unit is used. The original purpose is to limit the thermal stress generated in the accumulator. Therefore, the object of the present invention can also be achieved as a method of adjusting the spray amount by focusing on the temperature of the steam pipe metal at the inlet of the accumulator and the temperature difference.

Further, in the embodiment of the present invention, the control method is based on the current values of the superheated steam temperature and the main steam temperature, but the flow delay of the injected spray and the delay of the temperature control due to the heat capacity effect of the superheater heat transfer tube. When the predictive control in consideration of is performed, more stable and reliable temperature control can be realized. In other words, this is a method in which the spray amount as the manipulated variable is preliminarily controlled using a predicted value several minutes ahead instead of the current values of the superheated steam temperature and the main steam temperature. Such a method does not change the essence of the present invention.

Further, in the embodiment of the present invention, the steam generated from the waste heat boiler of each unit is directed to a plant having an equipment configuration in which the steam is introduced into an accumulator through a steam pipe.
The present invention can be applied to a plant of a type having a combustion type superheater separately installed in the middle of a steam pipe, where the superheater is further heated and then introduced into an accumulator. That is, in this plant, the object of the present invention can be achieved only by replacing the steam temperature control by the spray amount adjustment in the embodiment with the steam temperature control by the fuel amount adjustment in the combustion type superheater.

Further, in the embodiment of the present invention, the steam generated from the waste heat boiler of each unit is introduced into the accumulator via the steam pipe, and the steam (main steam) exiting the accumulator passes through the main steam pipe to the steam turbine. Although it is intended for a plant with equipment configuration to be introduced into the plant, it has a combustion type superheater separately installed in the middle of the main steam pipe, and this type is also used in a type plant that is further heated and then introduced into the steam turbine. The invention is applicable as it is. That is, in this plant, the object of the present invention can be achieved only by replacing the steam temperature control by the spray amount adjustment in the embodiment with the main steam temperature control by the fuel amount adjustment in the combustion type superheater.

[0023]

According to the present invention, the thermal efficiency of the plant can be improved by reducing the total spray amount used for controlling the steam temperature of a plurality of units.

The second effect of the present invention is that the capacity of the temperature reducer in each unit can be greatly reduced, and the equipment cost can be reduced.

Further, the third effect of the present invention is that the main steam temperature can be controlled stably while the temperature difference of the superheated steam generated from a plurality of units is kept within an allowable value, so that the safety is improved and the plant equipment is improved. Life consumption can be reduced.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of a steam temperature control unit according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of steam temperature control characteristics according to a conventional steam temperature control method and its problems.

FIG. 3 is a detailed functional block diagram of the steam temperature control means of the present invention.

FIG. 4 is an explanatory diagram showing control characteristics of steam temperature and the effect thereof according to the present invention.

[Explanation of symbols]

 1000: Waste incineration power plant.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F01K 11/00 F01K 11/00

Claims (9)

[Claims] 1. A waste heat boiler for recovering heat energy from a waste incinerator and its combustion gas to generate steam as one unit, and the temperature of steam generated from a plurality of units is set in the waste heat boiler. Has a control means that can be adjusted according to the spray amount of the desuperheater, steam from a plurality of units flow into a common accumulator and collectively,
In a refuse incineration power plant in which this collective steam is used as main steam and guided to a single steam turbine to generate power, the maximum temperature difference between steam from a plurality of units flowing into the accumulator is equal to or less than an allowable temperature difference and the generated steam temperature is reduced. If there is no unit that exceeds the allowable upper limit temperature, the target spray amount is not corrected.If there is a unit where the maximum temperature difference is equal to or more than the allowable temperature difference and the generated steam temperature exceeds the allowable upper limit temperature, the allowable upper limit temperature is set. If there is no unit in which the maximum temperature difference is equal to or greater than the allowable temperature difference and the generated steam temperature exceeds the allowable upper limit temperature, the temperature of the steam from the plurality of units flowing into the accumulator is set to the minimum. Steam temperature of a refuse incineration power plant characterized by reducing the amount of spraying of units exhibiting a value Your way. 2. A waste heat boiler for recovering thermal energy from a refuse incinerator and its combustion gas to generate steam is provided as one unit, and the temperature of steam generated from a plurality of units is installed in the waste heat boiler. Has a control means that can be adjusted according to the spray amount of the desuperheater, steam from a plurality of units flow into a common accumulator and collectively,
When the temperature of the main steam is higher than a target value in a refuse incineration power plant that generates power by introducing this collective steam to a single steam turbine without generating the main steam, a plurality of steam flows into the accumulator according to the deviation. If the temperature of the steam from the unit increases the spray amount of the unit having the highest value, and if it is lower than the target value, the temperature of the steam from the plurality of units flowing into the accumulator according to the deviation decreases to the lowest value. A method for controlling the steam temperature of a refuse incineration power plant, comprising reducing the amount of spraying of a unit indicating the following. 3. A waste heat boiler for recovering thermal energy from a refuse incinerator and its combustion gas to generate steam is a unit, and the temperature of steam generated from a plurality of units is set in the waste heat boiler. Has a control means that can be adjusted according to the spray amount of the desuperheater, steam from a plurality of units flow into a common accumulator and collectively,
In a refuse incineration power plant in which this collective steam is used as main steam and guided to a single steam turbine to generate power, the maximum temperature difference between steam from a plurality of units flowing into the accumulator is equal to or less than an allowable temperature difference and the generated steam temperature is reduced. If there is no unit that exceeds the allowable upper limit temperature, the target spray amount is not corrected.If there is a unit where the maximum temperature difference is equal to or more than the allowable temperature difference and the generated steam temperature exceeds the allowable upper limit temperature, the allowable upper limit temperature is set. If there is no unit in which the maximum temperature difference is equal to or greater than the allowable temperature difference and the generated steam temperature exceeds the allowable upper limit temperature, the temperature of the steam from the plurality of units flowing into the accumulator is set to the minimum. If the main steam temperature is higher than the target value, reduce the spray amount of the unit indicating the value. The temperature of the steam from the plurality of units flowing into the accumulator according to the deviation increases the spray amount of the unit having the highest value, and conversely, if the temperature is lower than the target value, flows into the accumulator according to the deviation. A method for controlling a steam temperature of a refuse incineration power plant, wherein the spray amount of a unit having a minimum value of steam from a plurality of units is reduced. 4. The apparatus according to claim 1, wherein the spray amount of the unit having the lowest temperature of the steam from the plurality of units flowing into the accumulator is zero when the spray amount is zero. A method for controlling a steam temperature of a refuse incineration power plant, wherein the spray amount of the unit having the highest steam temperature is adjusted. 5. The unit according to claim 1, wherein the temperature of the generated steam indicates a minimum value or a maximum value, so that the spray amount of the unit selected as the object of adjustment is zero or the capacity of the desuperheater. A steam temperature control method for a refuse incineration power plant in which a unit that generates steam indicating the next temperature when it is at a defined maximum limit is a target for adjusting the spray amount. 6. A unit including a refuse incinerator, a waste heat boiler for recovering thermal energy from combustion gas from the combustion gas to generate steam, and a combustion type superheater for raising the temperature of the generated steam. It has control means for adjusting the temperature of the steam generated from the unit in accordance with the amount of fuel supplied to the combustion type superheater, and the steam from a plurality of units is caused to flow into a common accumulator, and the steam is batched. In a refuse incineration power plant in which steam is guided to one steam turbine without generating main steam, a maximum temperature difference between steam from a plurality of units flowing into the accumulator is equal to or less than an allowable temperature difference and the generated steam temperature is an allowable upper limit. If there is no unit exceeding the temperature, the fuel input to the combustion type superheater is not corrected, the maximum temperature difference is greater than the allowable temperature difference, and the generated steam temperature is If there is a unit that exceeds the temperature, reduce the amount of fuel input to the combustion type superheater of the unit that exceeds the allowable upper limit temperature, reduce the maximum temperature difference to the allowable temperature difference or more and the generated steam temperature to the allowable upper limit temperature. The steam temperature of a refuse incineration power plant characterized by increasing the amount of fuel input to the combustion type superheater of the unit in which the temperature of the steam from the plurality of units flowing into the accumulator has the lowest value if no higher unit exists. Control method. 7. A waste heat boiler for recovering heat energy from a waste incinerator and its combustion gas to generate steam as one unit, and the temperature of steam generated from a plurality of units is installed in the waste heat boiler. Has a control means that can be adjusted according to the spray amount of the desuperheater, steam from a plurality of units flow into a common accumulator and collectively,
A control means for adjusting the collective steam in accordance with the amount of fuel supplied to a separately installed combustion superheater, wherein the steam superheated by the combustion superheater is used as main steam and one steam In a refuse incineration power plant that generates electricity by guiding it to a turbine, if there is no unit where the maximum temperature difference between steam from multiple units flowing into the accumulator is less than the allowable temperature difference and the generated steam temperature exceeds the allowable upper limit temperature, the target The spray amount is not corrected.If there is a unit where the maximum temperature difference is equal to or more than the allowable temperature difference and the generated steam temperature exceeds the allowable upper limit temperature, the spray amount of the unit that exceeds the allowable upper limit temperature is increased, and the maximum temperature is increased. If there is no unit whose difference is equal to or greater than the allowable temperature difference and the generated steam temperature exceeds the allowable upper limit temperature, multiple units flowing into the accumulator If the temperature of the main steam has a deviation from a target value, the amount of the spray of the unit having the minimum value of the steam from the unit should be reduced. A method for controlling a steam temperature of a refuse incineration power plant, comprising adjusting a fuel amount. 8. A method for controlling a steam temperature in a refuse incineration power plant according to claim 1, wherein the spray temperature is adjusted using a current value or a predicted value several minutes ahead. 9. The refuse incineration as claimed in claim 1, wherein the temperature of the metal at the inlet of the accumulator is used instead of the temperature of the steam flowing from each unit to the accumulator. Power plant steam temperature control method.