JPH10185435A - Method for controlling dry operation of powder dryer and dry operation controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably control dry operation even if supply amount and moisture content of powder to be supplied to a drying furnace are changed. SOLUTION: The powder dryer dries powder by supplying hot air generated from a hot air generating furnace 10 into a drying furnace 5 while continuously feeding the powder. A heat quality set value MV0 for drying powder of standard state to a predetermined water content is calculated in response to a supply quantity Q to the furnace 5, exhaust gas temperature T of the furnace 5 is sampled at a predetermined sampling period. A heat quantity regulator operation signal MV generated from a temperature regulator 37 in response to a deviation of the temperature from an exhaust gas set temperature To is converted to correction values MV1 , MV2 for increasing and decreasing the value MV0 , and added to the value MV0 . With the value MV0 to which the correction value is added as a target value an introducing heat quantity of the regulating part of the furnace 10 is regulated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drying control method and a drying control device in a powder drying apparatus for drying powder such as wet incinerated ash.

[0002]

2. Description of the Related Art Generally, incinerated ash from municipal waste passes through water after incineration and is in a wet state (for example, a water content = 15 to 30).
%), In order to further supply it to the ash melting furnace to reduce the volume, it must first be dried by a drying device until a predetermined moisture content (for example, 5% or less) is reached. As this drying device, for example, as shown in FIG. 7, a continuous drying furnace 5 such as a rotary kiln is used.
In general, hot air generated by combustion of fuel in the hot air generating furnace 10 is introduced into the furnace of the drying furnace 5 to dry the incinerated ash 2 continuously transferred in the furnace.

The temperature T of the exhaust gas flowing out of the drying furnace 5 is detected by a temperature detector 15 in order to make the moisture content of the ash 26 discharged from the drying furnace 5 equal to or less than a predetermined value.
This temperature is the exhaust gas set temperature T by the temperature setter 36.
₀ (for example, 130 ° C.).
In general, a feedback control system in which the opening degree of a fuel flow control valve 14 provided in a fuel supply pipe 11 to the fuel supply pipe 11 is adjusted by a temperature controller 37 and a flow controller 14a is adopted. In the figure, 14b is a fuel flow rate detector. In some cases, a valve opening instruction is directly given to the fuel flow control valve 14 without using these.

However, in the above control method, when the supply amount of the incinerated ash 2 supplied to the drying furnace 5 or the water content changes, stable control is difficult, and large overshoot or hunting of the exhaust gas temperature is likely to occur. As a result, there are problems that the moisture content of the ash after drying becomes equal to or higher than a predetermined value and that the fuel is wasted due to overdrying.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and enables stable control even when the supply amount of the powder supplied to the drying furnace or the moisture content changes. It is an object of the present invention to provide a drying control method and a drying control device for a powder drying apparatus, in which a change in the moisture content of the ash afterwards is small and the waste of fuel due to overdrying can be prevented.

[0006]

According to the present invention, there is provided a method for controlling a powder drying apparatus, comprising: flowing hot air generated in a hot air generating furnace into a furnace of a drying furnace; and continuously transferring powder charged in the furnace. In a powder drying apparatus for drying with the hot air while drying, a drying control method for controlling the moisture content of the powder by adjusting the amount of heat input in a calorie adjusting unit of the hot air generating furnace, wherein the powder having a standard property A calorific value for drying the powder to a predetermined moisture content is calculated according to the supply amount of the powder to the drying furnace, and the temperature of the exhaust gas flowing out of the furnace body is sampled at a predetermined sampling cycle. The calorie controller operation signal generated by the temperature controller in accordance with the deviation between the temperature and the exhaust gas set temperature is converted into a correction value for increasing or decreasing the calorie set value, and is added to the calorie set value. did Serial and performs adjustment of the heat input in the heat regulating unit heat quantity setting value as a target value.

Further, the control device of the powder drying apparatus according to the present invention is characterized in that the hot air generated in the hot air generating furnace is circulated in the furnace of the drying furnace, and the powder charged in the furnace is continuously transferred by the hot air. In a powder drying device for drying, a drying control device for controlling the moisture content of the powder by adjusting the amount of heat input in the calorific value adjustment unit of the hot air generator,
A calorific value setting unit that outputs a calorific value set value for drying the powder of the standard property to a predetermined moisture content according to a supply amount of the powder to the drying furnace, and a temperature of exhaust gas flowing out of the furnace body. A temperature controller that samples a predetermined sampling cycle and issues a calorie control unit operation signal according to the deviation between the temperature and the exhaust gas set temperature, and the calorie control unit operation signal,
A signal conversion unit that converts the calorific value set value into a correction value to increase or decrease, and a correction value adding unit that adds the correction value to the calorific value set value and outputs the calorific value adjustment unit as a target value of the input calorific value. It is characterized by the following.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows the entire incineration ash treatment apparatus, and 1 is an incineration ash hopper, which is in a wet state (water content = 15 to 30) discharged from a municipal solid waste incineration apparatus (not shown).
%), For temporarily storing the incinerated ash 2, and a fixed-quantity cut-out device 3 (may be a vibrating feeder) including a screw feeder is attached to a lower portion of the incinerated ash 2. Reference numeral 4 denotes a conveyor for incineration ash transport, which is located just below the discharge port of the fixed quantity cutting device 3.
It is disposed above the ash supply port 6 of the drying furnace 5.

The drying furnace 5 is a rotary kiln type drying furnace for drying incinerated ash continuously transferred in the furnace body 7 by hot air flowing through the furnace body 7. It has a hot air generator 10 of the type.
The hot-air generating furnace 10 burns fuel supplied from a fuel supply pipe 11 in a burner 12 and heats air supplied from an air supply port 13 to generate heated air in one end of a furnace body 7 of a drying furnace 5. To be supplied to The illustration of the combustion air supply system of the burner 12 is omitted.

Exhaust gas (hot air) discharged from the exhaust port 8 at the other end of the furnace body after flowing through the furnace body 7 and drying the incinerated ash flows through an exhaust path 21 and passes through a bag filter type dust collector 22. After that, the air is sucked by the exhaust fan 23 and discharged from a chimney (not shown). Reference numeral 14 denotes a fuel flow control valve provided in the fuel supply pipe 11 and serves as a calorie control unit of the hot-air generating furnace 10. Reference numeral 15 denotes a temperature detector provided in the exhaust path 21.
Connected to 0. 25 is an ash melting furnace, and a drying furnace 5
The dried ash 26 discharged from the ash is conveyed by a conveyor 27 and is introduced into the ash melting furnace 25 for melting.

Next, FIG. 2 shows a control device 60 of the drying furnace 5, and the same parts as those in FIG. 1 are denoted by the same reference numerals. Reference numeral 30 denotes a heat amount setting unit, and 31 denotes an ash supply amount setting unit which emits the ash supply amount (supply weight per unit time) Q of the incinerated ash 2 to the drying furnace 5 by the fixed quantity cutting device 3 as a set value. It is. Reference numeral 32 denotes a timer for changing the amount of incinerated ash extracted by the fixed amount extracting device 3 to change the ash supply amount Q, and the time until the incinerated ash whose supply amount has been changed reaches the drying furnace 5. After the delay time corresponding to the time required for transportation by the conveyor 4 from the portion immediately below the fixed quantity cutting device 3 to the ash supply port 6, the changed ash supply amount Q is used to compensate for the delay. 33.

The function generator 33 supplies incineration ash 2 having a standard property having an average moisture content (for example, 20%) and particle size to the drying furnace 5 with a supply amount Q from one incineration ash hopper.
Burner 1 necessary for drying to a predetermined moisture content (for example, 5% or less) by the drying furnace 5 when supplied.
The fuel flow rate data (MV ₀ ) of the fuel flow rate control valve 14 corresponding to the heating amount in the two parts is incorporated as a curve relational expression obtained by performing a trial operation for each ash supply amount Q,
To output the result as calculated by heat setting value of the fuel flow rate setting signal MV ₀ in accordance with The ash supply amount to the input of ash supply quantity Q, the signal MV ₀ represents fuel flow rate control through the correction value adding section 51 It is provided to the flow controller 14a of the valve 14. 14
b is a fuel flow rate detector. This flow controller 14a
, The valve opening signal MV ₀ may be directly supplied to the fuel flow control valve 14 as the heat amount setting value.

On the other hand, reference numeral 36 denotes a temperature setting for setting an exhaust gas set temperature T ₀ corresponding to the exhaust gas temperature of the drying furnace 5 when the above-described incinerated ash 2 having the standard properties is dried to a predetermined moisture content. The temperature controller 37 takes in the detected temperature (exhaust gas temperature) T of the temperature detector 15 at a predetermined sampling cycle, and calculates a deviation e ₀ between the set temperature T ₀ and the detected temperature T by a deviation calculating unit 37a. The deviation e ₁ obtained by giving the dead zone n by the dead zone processing unit 37b (see FIG. 3) is subjected to PID calculation by the temperature control calculation unit 37c, and the valve operation signal of the fuel flow control valve 14, which is the heat amount adjustment unit operation signal. MV (0
100%) until the next sampling.

[0014] 40 is a signal converter for converting a valve operating signal MV to the correction value for the fuel flow rate setting signal MV _0,
The signal MV is read as a positive / negative signal based on the opening of 50%, and the upper and lower limits are set to, for example, ± 10% and +.
According to the fold lines 41 and 42 restricted to 10-20%, M
Two function generators 43 and 44 that output correction values MV ₁ and MV ₂ from V are connected to a switch 45 at one end through a changeover switch 45.
Connected in parallel. The function generator 43 is for continuously supplying ash to the drying furnace 5, the function generator 44 is for stopping ash supply to the drying furnace 5, and the changeover switch 45 is a monitoring device (not shown) for monitoring the entire incineration ash processing device. Lower limit value change command S from
_{According to 1} , the contact is switched to the contact point a or b depending on the supply state of the incineration ash (the operation state of the fixed quantity cutting device 3 in FIG. 1), and the switching point and the like will be described later.

The monitoring device sends a sampling cycle switching command S ₂ and an MV initial value setting command S ₃ to the temperature controller 37. Since the time of the ash supply stop to the drying furnace 5, becomes overheated can not follow a temperature change in the sampling period (e.g. 10 minutes) at the ash continuous supply for the disturbance is large, the sampling period switching command S ₂
The sampling period was shortened by (e.g. 2 minutes), at the same time the lower limit of the correction value by switching the changeover switch 45 to the function generator 44 side by the lower limit value changing command S ₁ -10%
To -20% to facilitate quick drive of the fuel flow control valve 14 in the closing direction to prevent an overheating state. The MV initial value setting instruction S _3, when the ash supply amount Q is changed, it is for outputting the MV = 50 (%) as an initial output of the temperature adjusting meter 37 in a timed elapse of the timer 32 Thus, the initial correction value when the supply amount Q is changed becomes zero, and overshoot and hunting of the control system at the time of the change are prevented.

Numeral 51 denotes a correction value adding section composed of an adder. The correction value adding section MV ₁ generates a correction value MV ₁ generated by the signal conversion section 40 in response to a fuel flow rate setting signal (heat amount setting value) MV ₀ generated by the heat setting section 30.
Alternatively, MV ₂ is added and output to the fuel flow control valve 14 as a target value of the amount of heat input. 2, the illustration of the combustion air supply system and the combustion (air-fuel ratio) control system of the burner 12 is omitted.

The control method by the control device 60 having the above configuration will be described below. During continuous supply of the incinerated ash 2 to the drying furnace 5, the function generator 33 is controlled to a standard property according to the ash supply amount Q. It outputs a fuel flow rate set value signal MV ₀ of a fuel flow rate control valve 14 corresponding to a calorific value of a burner unit for drying the incinerated ash 2 to a predetermined moisture content by passing through the furnace body 7 of the drying furnace 5. The correction value is supplied to the flow controller 14 a of the fuel flow control valve 14 via the correction value adding section 51.

When the moisture content of the incinerated ash 2 is higher than that of the incinerated ash of the standard property, the temperature of the exhaust gas flowing out of the furnace 7 is the set exhaust gas temperature T ₀ which is the hot air temperature for the incinerated ash of the standard property. less than next, also larger becomes the temperature of the exhaust gas is an exhaust gas set temperature T ₀ is smaller Conversely, since they produce deviations against T ₀ in either case, the temperature adjusting meter 37 is a temperature detector at a predetermined sampling period The PID calculation is performed on the difference between the detected temperature T of the exhaust gas detected by the step 15 and the exhaust gas set temperature T ₀ generated by the temperature setting device 36, and a valve operation signal (heat amount control unit operation signal) MV is output.

The signal MV is converted into a correction value MV ₁ by the function generator 43 of the signal conversion unit 40, and the fuel flow rate setting signal (heat value setting value) MV is output by the correction value adding unit 51.
₀ is added to the given fuel flow rate control valve 14, fuel flow rate control valve 14 is further MV ₁ minute by opening direction relative to the valve opening degree corresponding to the fuel flow rate setting signal MV ₀ (MV> 50%
) Or in the closing direction (when MV <50%), whereby the incinerated ash 2 is dried to a predetermined moisture content, discharged from the furnace body 7, and discharged from the furnace body 7. T is also maintained at the set temperature T ₀ .

As described above, since the setting of the fuel flow rate (calorific value) with respect to the ash supply amount Q of the incinerated ash 2 is performed by the calorific value setting section 30, the feedback control by the temperature controller 37 determines the properties of the incinerated ash 2 (moisture content). This is performed only for fluctuations of the content and the particle size). In addition, the sampling control is performed at a predetermined sampling cycle, and only a small correction value with upper and lower limits cut off is added to the fuel flow rate setting signal MV ₀ . In addition, it is possible to perform stable powder drying control without causing excessive overshoot or hunting due to excessive correction by the feedback control.

Further, in this specific example, more stable control is performed by adding the dead zone n in the dead zone processing section 37b of the temperature controller 37.

When the supply amount of the incineration ash 2 to the furnace body 7 is changed, a new ash supply amount Q is set by the ash supply amount setting device 31 in synchronization with the change of the cutting speed of the fixed quantity cutting device 3. the delayed action by the timer 32, the fuel flow rate setting signal MV ₀ new when it reaches approximately ash 2 ash supply port 6 parts that have changed the supply amount is outputted, and by the MV initial value setting command S ₃ Since the temperature controller 37 generates an initial output of MV = 50%, overshoot and hunting of the control system due to the change in the ash supply amount are suppressed to a small amount.

Further when the ash supply stop to the furnace body 7, the lower limit value changing command S ₁ by the changeover switch 45 is lowered lower limit value of the correction value generated by the contact b switched by the signal converting unit to the side 40, further sampling the sampling period of the temperature adjusting meter 37 by the periodic switching command S ₂ is switched in a short period of time (e.g., 2 minutes). Accordingly, the amount of heat input to the hot-air generating furnace 10 can be rapidly reduced in response to the rapid rise in the exhaust gas temperature accompanying the decrease in the amount of the supplied ash 2 in the furnace body 7 (therefore, the amount of moisture in the furnace body), Fuel consumption due to overheating can be prevented.

[0024] Then drying furnace ash supply to 5 is resumed, the correction value MV ₂ is upon entering the upper and lower limit values of MV ₁ in (± 10%), the command S ₁ than the monitoring device, S ₂ the correction value output of the signal converter 40 is switched to MV _1, the sampling period of the temperature adjusting meter 37 is returned to the cycle at the ash continuous supply.

Next, FIG. 4 shows another embodiment of the signal converter 40. In the figure, reference numeral 46 denotes a positive / negative increase / decrease signal M obtained by subtracting 50% of the median value from the valve operation signal MV of the temperature controller 37.
V limiter 'subtractor for converting the, 47 that this decrease signal MV' outputs a correction value MV ₁ restricts the upper and lower limit ± 10%, 48 are also increased or decreased signal MV 'the upper limit of 10%, the lower limit -
A limiter that outputs a correction value MV ₂ by limiting the correction value to 20%, 45
Is the same changeover switch as described above.
Even with 0A, the same operation as that of the signal conversion unit 40 can be obtained.

Next, another embodiment of the present invention will be described with reference to FIG. In the figure, the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description thereof will be omitted. This specific example differs from the specific example only in the signal conversion unit 70 and the correction value adding unit 52. That is, the function generator 71 for continuously supplying ash converts the valve operation signal MV into a ratio with respect to the center value 50%, and sets the upper and lower limits of this ratio to ± 10%.
And outputs the correction value alpha ₁ according to fold lines 72 is limited to (0.9 to 1.1). The function generator 73 for stopping the ash supply has a lower limit value of the above ratio of −20% (0.8).
Another is in accordance with fold line 74 is the same as the fold line 72, and outputs the correction value alpha _2.

The correction value adding section 52 is composed of a multiplier. The correction value α ₁ or α ₂ selectively output by the changeover switch 45 is multiplied by the fuel flow rate setting signal MV ₀ generated by the heat quantity setting section 30. , The fuel flow control valve 14 has α ₁ M
A fuel flow rate setting signal of V ₀ or α ₂ MV ₀ is given as a heat quantity setting value.

[0028] That is, while the correction value MV ₁ or MV ₂ as a valve opening signal in the control device 60 of the embodiment is added to the fuel flow rate setting signal MV _0, the controller of this embodiment (FIG. 3) correction value alpha ₁ or alpha ₂ fuel flow rate setting signal as the ratio of dimensionless At 61 (heat quantity set value) MV
_The multiplication is performed by ₀ , and the same operation is obtained in both devices. Thus, similarly to the control device 60, the control device 61 can perform stable drying control of the powder with little overshoot and hunting.

FIG. 6 shows another embodiment of the signal converter 70. In the figure, reference numeral 76 denotes a value obtained by subtracting the median value 50% from the valve operation signal MV of the temperature controller 37 by 100%. A computing unit 77 adds a ratio 1.0 for correction 0 to the ratio signal α ₀ and converts the ratio signal α ₀ into upper and lower limits ± 10% and outputs a correction value α _1. ,
Numeral 78 also indicates that the ratio signal α ₀ has an upper limit of 10% and a lower limit of -20%
And a limiter 45 for outputting the correction value α _2, which is the same switch as described above. The same operation as that of the signal conversion unit 40 can be obtained by the signal conversion unit 70A of FIG.

The present invention is not limited to the above specific examples and embodiments. For example, the configuration of the control device may be other than the above, and each signal processing uses a computer in addition to the analog processing method. A digital processing method may be used. The timer 32 may be omitted depending on the layout of the drying furnace, and the dead zone n may be omitted when the offset is to be reduced as much as possible.

The present invention can also be applied to a drying apparatus for powder other than incineration ash, a continuous drying furnace other than a rotary kiln, and a drying apparatus having a hot air generating furnace other than a combustion type.
For example, in the case of an electric heater type hot air generating furnace or a hot air generating furnace using an electric heater and a burner in combination, the calorific value set value with the correction value is given to a thyristor which is a calorie adjusting unit of the electric heater as a calorific value setting signal, for example. I just need.

[0032]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples.

EXAMPLE Using the incineration ash treatment device shown in FIG. 1 and the control device of the drying furnace shown in FIG. 2 (however, the dead zone width n = ± 5 ° C. in the dead zone processing section 37 b), the exhaust gas set temperature T by the temperature setting device 37. Control was performed at ₀ = 130 ° C. At this time, incineration ash 2
Exhaust gas due to fluctuations in water content (30 to 15%) of the incineration ash 2 and the supply amount Q = 3.0 tf / H by the quantitative extraction device 3 and fluctuations (disturbances) in the respective operating conditions of supply stop and resupply start FIG. 7 shows an example of the fluctuation state of the temperature T.

COMPARATIVE EXAMPLE The same incineration ash processing apparatus as in the embodiment and the conventional example in which the output of a temperature controller 37 (but no dead zone processing section 37b) is directly input to a flow controller 14a of a fuel flow control valve 14 as shown in FIG. When the drying control is performed at the exhaust gas set temperature T ₀ = 130 ° C. by the temperature setting device 37 using the controller of the drying furnace of the above, the exhaust gas with respect to the fluctuation of the water content and the supply amount of the incinerated ash 2 is the same as in the above embodiment. FIG. 8 shows an example of a variation situation of the temperature T.
Shown in

As can be seen from these figures, in the comparative example (prior art), the fluctuation of the exhaust gas temperature T is large and the intervention of the operator is required. On the other hand, according to the present invention, the fluctuation of the exhaust gas temperature T is small, No operator intervention was required, and the exhaust gas temperature T could be maintained at the allowable temperature of 160 ° C. or lower in a fully automatic operation.

[0036]

As described above, according to the present invention,
The temperature of the exhaust gas flowing out of the furnace is sampled, and the calorie control unit operation signal, which is a feedback signal generated by the temperature controller, is converted into a correction value and added to the calorie set value according to the amount of powder supplied to the drying furnace. The obtained value is given to the calorific value generating section of the hot blast furnace as the target value of the calorific value of heat, so that the correction with the above correction value is performed only for the variation of the properties such as the water content and the particle size other than the supply amount of the powder. On the other hand, since the drying is performed at a predetermined sample cycle, stable drying control of the powder can be performed without generating large overshoot or hunting, the fluctuation of the moisture content of the ash after drying is small, and the fuel Waste can also be prevented.

[Brief description of the drawings]

FIG. 1 is a system diagram of an incineration ash treatment apparatus showing a specific example of the present invention.

FIG. 2 is a control system diagram of a drying oven in the apparatus of FIG.

FIG. 3 is a detailed diagram showing processing contents of a dead zone processing unit in FIG. 2;

FIG. 4 is a system diagram showing another embodiment of the signal converter in FIG. 2;

FIG. 5 is a diagram corresponding to FIG. 2, showing another specific example of the present invention.

FIG. 6 is a system diagram showing another embodiment of the signal converter in FIG. 4;

FIG. 7 is a control characteristic diagram showing one embodiment of the present invention.

FIG. 8 is a diagram corresponding to FIG. 7 showing a comparative example according to a conventional method.

FIG. 9 is a control system diagram showing an example of a conventional incineration ash drying device.

[Explanation of symbols]

2 ... incineration ash, 5 ... drying furnace, 7 ... furnace body, 10 ... hot air generating furnace, 11 ... fuel supply pipe, 12 ... burner, 14 ... fuel flow rate control valve, 15 ... temperature detector, 30 ... calorie setting unit, 31 ...
Ash supply amount setting unit, 33: function generator, 36: temperature setting unit, 37: temperature controller, 40: signal conversion unit, 40A: signal conversion unit, 43: function generator, 44: function generator, 45
... Changeover switch, 46 ... Subtractor, 47 ... Limiter, 48
... Limiter, 51 ... Correction value addition section, 52 ... Correction value addition section, 60 ... Control device, 61 ... Control device, 70 ... Signal conversion section, 70A ... Signal conversion section, 71 ... Function generator, 73 ... Function generator , 76: arithmetic unit, 77: limiter, 78: limiter.

Claims (2)

[Claims] 1. A powder drying apparatus for flowing hot air generated in a hot air generating furnace through a furnace of a drying furnace and drying the hot air while continuously transferring the powder charged in the furnace, wherein the hot air generating apparatus comprises: A drying control method for controlling the moisture content of the powder by adjusting the amount of heat input in a calorie control unit of a furnace, wherein the calorific value for drying the powder having a standard property to a predetermined moisture content is set to the powder. While calculating according to the supply amount of the body to the drying furnace, the temperature of the exhaust gas flowing out of the furnace body is sampled at a predetermined sampling cycle, and a temperature controller according to a deviation between the temperature and the set exhaust gas temperature. The generated calorie control unit operation signal is converted into a correction value for increasing or decreasing the calorie set value and is added to the calorie set value, and the calorie set value to which the correction value is added is set as a target value in the calorie adjuster. A drying control method for a powder drying apparatus, comprising: adjusting a heat input. 2. A powder drying apparatus for flowing hot air generated in a hot-air generating furnace through a furnace of a drying furnace and drying the hot-air while continuously transferring powder charged in the furnace, A drying control apparatus for controlling the moisture content of the powder by adjusting the amount of heat input in a calorie adjustment unit of a furnace, wherein the calorific value for drying the powder having a standard property to a predetermined moisture content is the powder. A calorific value setting unit for outputting a temperature according to a supply amount of the body to the drying furnace, and a calorific value according to a deviation between the temperature and the exhaust gas set temperature by sampling the temperature of the exhaust gas flowing out of the furnace body at a predetermined sampling cycle. A temperature controller for issuing a control section operation signal, a signal conversion section for converting the calorie control section operation signal to a correction value for increasing or decreasing the calorie set value, and adding the correction value to the calorie set value to produce the calorie. For the adjustment unit A drying control device for a powder drying device, comprising: a correction value adding unit that outputs a target value of the amount of heat input.