JPS63158604A - Furnace pressure controller - Google Patents

Abstract

PURPOSE:To improve the controllability and prevent previously the occurrence of a hunting phenomenon or the like by performing temperature compensation in consideration of expansion and contraction of gas in a furnace due to the change of the temperature in the furnace. CONSTITUTION:A fuel flow rate and an air flow rate obtained by a fuel flow rate detector 29 and an air flow rate detector 30 are synthesized by addition in an additive synthesizing part 31 to obtain a gas inflow rate in the furnace. The temperature in the furnace from a furnace temperature detector 32 is operated to extract its square root by a square root extracting operation part 33 and a temperature correction coefficient is obtained, and the gas inflow rate in the furnace is multiplied by the temperature correction coefficient and a feed forward coefficient (k) in a feed forward controlled variable operating means 37 to obtain a feed forward controlled variable. This controlled variable is compensated for disturbance and is taken out through a feed forward model 38 and is added to the output of a furnace pressure regulator 35 to obtain an operation signal. Thus, the controllability is improved and the occurrence of a hunting phenomenon or the like is prevented.

Description

[Detailed description of the invention] [Object of the invention] (Industrial application field) The present invention relates to a furnace pressure control device for controlling the furnace pressure of a heating furnace, a cooling furnace, etc. Regarding a furnace pressure control device.

(Prior Art) This type of furnace pressure control device improves the combustion efficiency in the furnace by constantly balancing the amount of inflow gas for combustion input into the furnace and the amount of outflow gas flowing out of the furnace. This is also an important requirement from the point of view of heating the materials in the furnace to a predetermined temperature.

Therefore, conventionally, in order to realize a heating furnace that satisfies the above requirements, an in-furnace pressure control device as shown in Fig. 3 is added to the heating furnace to control the in-furnace pressure to a predetermined value. are doing. That is, this device supplies fuel and air to the combustion burner 1 to perform combustion and heat the material inside the heating furnace 2 to a predetermined temperature, and also separately supplies fuel to the fuel supply path and the air supply path. After a flow rate detector 3 and an air flow rate detector 4 are provided to detect the fuel flow rate and the air flow rate, these detected flow rates are added and combined by an addition/synthesis section 5 to determine the amount of gas flowing into the furnace. Further, a multiplier 6 multiplies the amount of gas flowing into the furnace by the feedforward coefficient, and the signal obtained by this multiplication is passed through a feedforward model 7 to obtain a disturbance compensation signal 8. On the other hand, a furnace pressure detector 9 is attached to the heating furnace 2, and the furnace pressure signal detected by the furnace pressure detector 9 is guided to the furnace pressure regulator 10, where the deviation between the detected pressure in the furnace and the target value Sv is determined. Based on this, an adjustment calculation is performed to obtain a furnace pressure adjustment signal 11. Then, this furnace pressure adjustment signal 11 and the disturbance compensation signal 8 are added in an adder 12 to obtain an operation signal, and this operation signal is used to operate the operation end 13 to adjust the amount of outflow gas flowing out of the furnace. As a result, the pressure inside the furnace is controlled to a predetermined value.

By the way, in the above-mentioned furnace pressure control device, if the amount of gas flowing into the furnace and the amount of gas flowing out of the furnace are equal, the pressure inside the furnace will always remain stable, but if the temperature inside the furnace is When this changes, the degree of expansion of the gas changes, and the pressure inside the furnace changes accordingly. Therefore, when this device executes feedforward control based on the amount of gas flowing into the furnace obtained at or near a specific temperature, the original compensation effect of feedforward control is properly achieved, but the If the temperature inside the furnace changes significantly, the compensation effect of feedforward control will be greatly reduced.

Further, if the degree of expansion of the amount of gas flowing into the furnace and the amount of gas flowing out of the furnace changes due to a change in the temperature inside the furnace, the process gain of the pressure inside the furnace changes.

(Problem to be Solved by the Invention) Therefore, in the above-mentioned control device, there is a problem that the compensation effect of the feedforward control is reduced due to changes in the temperature inside the furnace, and the controllability of the process is significantly reduced. be. Further, when the degree of expansion of the amount of gas flowing into the furnace and the amount of gas flowing out of the furnace changes due to a change in the temperature inside the furnace, mismatching of control gains occurs, which causes problems such as hunting and underdamping.

The present invention has been made in view of the above-mentioned circumstances, and by performing temperature compensation in consideration of the expansion and contraction of the gas amount in the furnace due to changes in the temperature inside the furnace, the compensation effect of feedforward control is enhanced, and the feedback control It is an object of the present invention to provide a furnace pressure control device that can optimize gain, improve controllability, and prevent hunting phenomena.

[Structure of the Invention] (Means for Solving the Problems) The furnace pressure control device according to the present invention is provided with means for acquiring the amount of gas flowing into the furnace, detects the fuel flow rate and the air flow rate, and acquires the amount of gas flowing into the furnace. At the same time, a temperature correction coefficient obtaining means is provided on the output side of an in-furnace temperature detector attached to the furnace to obtain a temperature correction coefficient based on the in-furnace temperature detected from the in-furnace temperature detector. By providing this temperature compensation means to obtain a temperature compensation signal using the temperature compensation coefficient of the temperature compensation coefficient obtaining means and applying this temperature compensation signal to the furnace pressure adjustment signal that is the output of the furnace pressure regulator, Control is performed so that the amount of exhaust gas inside the furnace and the amount of gas flowing out of the furnace are balanced against changes in the temperature inside the furnace.

(Function) Therefore, by using the above means, the temperature correction coefficient is changed according to the change in the furnace temperature from the furnace temperature detector using the temperature correction means, and the feedforward control of the amount of gas flowing into the furnace is performed. By changing the amount of compensation in the system and applying a temperature correction coefficient to the output of the furnace pressure controller as necessary to set the feedback control gain to the optimal gain, the inflow and outflow gases can be adjusted regardless of changes in the furnace temperature. Control is performed to balance the amounts, thereby improving controllability and eliminating mismatching of control gains.

(Example) Hereinafter, an example of the apparatus of the present invention will be described with reference to FIG. In the figure, reference numeral 20 denotes a furnace for heating or cooling required materials to a predetermined temperature, and combustion medium supply means 21 for supplying fuel and air to this furnace 20. Inflow gas amount acquisition means 22 for obtaining the amount of inflow gas for combustion. Temperature correction coefficient acquisition means 23, pressure adjustment means 24 for controlling the furnace pressure to be constant
A temperature correction means 25 and the like are provided.

The combustion medium supply means 21 includes a combustion burner 2 in the furnace 20.
6 is attached to the furnace, and receives fuel and air through a fuel supply path 27 and an air supply path 28 to perform combustion operation in the furnace. The inflow gas melon acquisition means 22 has a fuel flow rate detector 29 and an air flow rate detector 30 separately attached to the fuel supply path 27 and the air supply path 28, and adds and synthesizes the outputs of both of these detectors 29 and 30. 31 and performs additive synthesis to obtain the amount of gas flowing into the furnace.

The temperature correction coefficient acquisition means 23 includes a furnace temperature detector 3 at an appropriate location in the furnace 20 for detecting the atmosphere (gas) lA degrees inside the furnace.
2 is attached, and a square root calculation section 33 is connected to the output side of the furnace temperature detector 32 to perform a square root calculation of the detected temperature in the furnace to obtain a temperature correction coefficient.◎ The pressure adjustment means 24 is a conventionally well-known feedback control system, which includes a furnace pressure detector 34 and a furnace pressure regulator 35.
It has a function of applying the output of the furnace pressure regulator 35 to the operating end 36 to adjust the amount of gas flowing out of the furnace.

The temperature correction means 25 includes a feedforward control amount calculation means 37 that multiplies the amount of gas flowing into the furnace by a feedforward coefficient and a temperature correction coefficient to obtain a feedforward control amount, and a disturbance compensation using this feedforward control amount. Feedforward model for acquiring signals 38
and an addition calculation section 39 that adds a disturbance compensation signal to the furnace pressure adjustment signal of the furnace pressure regulator 35 to obtain an operation signal. .

Next, the operation of the apparatus configured as above will be explained.

Generally, the furnace pressure is adjusted by comparing the detected pressure in the furnace obtained by the furnace pressure detector 34 with the target value SV using the furnace pressure regulator 35, and performing adjustment calculations to make the deviation zero. Obtain an adjustment signal, further add a disturbance compensation signal for feedforward control related to the amount of gas flowing into the furnace to the furnace pressure adjustment signal to obtain an operation signal,
This is applied to the operating end 36 to adjust the amount of gas flowing out of the furnace, thereby balancing the amount of gas flowing into the furnace and the amount of gas flowing out of the furnace.

However, since the amount of gas in the furnace expands and contracts due to temperature changes in the furnace, the disturbance compensation effect of feedforward control related to the amount of gas flowing into the furnace is reduced, and controllability is reduced. Therefore, the fuel flow rate and the air flow rate obtained by the fuel flow rate detector 29 and the air flow rate detector 30 are added together by a synthesis unit 31.
The amount of gas flowing into the furnace is determined by addition and synthesis in the furnace temperature detector 32, and the square root calculation section 33 performs a square root calculation of the temperature inside the furnace from the furnace temperature detector 32 to obtain a temperature correction coefficient. The amount of gas flowing into the furnace is multiplied by the temperature correction coefficient and the feedforward coefficient to obtain a feedforward control amount, and this control amount is taken out as a disturbance compensation signal via the feedforward model 38 and sent to the furnace pressure regulator 35. After obtaining an operation signal in addition to the output of , this is applied to the operating end 36 to control the amount of gas flowing out of the furnace, thereby maintaining a balance between the amount of gas flowing into the furnace and the amount of gas flowing out of the furnace.

The reason for providing the temperature compensating means having the above configuration is as follows. First, as a specification related to furnace pressure control, the amount of gas flowing into the furnace is F o ! (Nm3/h).

The amount of gas flowing out of the furnace at the standard temperature (for example, 20'C) is F.
GO (N13/l,), the furnace temperature at the present time, the amount of gas flowing out of the furnace in the pressure state as FOX (+g3/h), the operating amount in the furnace as Mva (%), and the temperature inside the furnace as T ("k ).Here, in order to keep the pressure inside the furnace constant, the amount of gas flowing into the furnace and the amount of gas flowing out of the furnace must be equal.In other words, using the above specifications, Fao=FaI ・=( 1) The following relationship needs to hold.Next, if the furnace pressure operating end 36 has a linear characteristic (including the case where it has a linear characteristic by characteristic correction), the outflow gas from the furnace at the present time m F G The operation j1Mvc is proportional to the flow coefficient cv of the operation end 36 (which represents the relationship between the operation amount and the opening degree, and is "1" when considered as a linear characteristic) and the furnace temperature T.
From the conditions, Mv c−k −Fax ・(1/J1r)
・= It is expressed as (2). , now the amount of gas flowing out of the reactor is pa.

(N13/h), the above equation (2) is MvG-
ni'・T-FGo・(ll-rf)-ni' ・-1
It can be replaced with the formula 'T-Fco-(3).

Therefore, from equations (2) and (3), Mv a = ni' ・f d ・Fo 1 − (4
) is obtained. In other words, the operation ffiMva is the furnace temperature T
It can be seen that the manipulated variable is proportional to the square root value of . This can be achieved by adding a temperature correction coefficient based on the temperature inside the furnace to the amount of gas flowing into the furnace to determine the feedforward control amount. High feedforward control can be performed.

Therefore, according to the configuration of the embodiment described above, even if the furnace pressure is the same, a temperature correction coefficient proportional to the square root value of the furnace temperature is obtained according to changes in the furnace temperature, and the amount of gas flowing into the furnace is adjusted. Since the feedforward control amount is determined by multiplying the temperature correction coefficient in addition to the feedforward coefficient, feedforward control can be performed appropriately even if the gas volume expands or contracts due to changes in the furnace temperature. controllability can be greatly improved. Moreover, if feedforward control is performed appropriately, the combustion efficiency in the furnace by the combustion burner 26 can be increased, and the material can be heated at an optimal temperature.

In the above embodiment, a temperature compensation element is added to the feedforward control compensation means, but as shown in FIG. 2, a compensation element for changes in furnace temperature can also be added to the feedback control system. . That is, a gain correction means 41 having a multiplication function is provided between the furnace pressure regulator 35 and the addition calculation section 39, and here, the feedback adjustment signal from the furnace pressure regulator 35 is obtained by the temperature correction coefficient acquisition means 23. The feedback control gain may be corrected by multiplying it by a temperature correction coefficient, and the disturbance compensation signal may be added to the adjustment signal whose gain has been corrected by the gain correction means 41 to obtain the operation signal. Therefore, with such a configuration, the compensation effect of the feedforward control related to the amount of gas flowing into the furnace can be sufficiently exerted against changes in the furnace temperature, and mismatching of the control gain of the furnace pressure control can be eliminated. Hunting and underdamping can be prevented from occurring.

In addition, the present invention can be implemented with various modifications without departing from the gist thereof.

[Effects of the Invention] As detailed above, according to the present invention, the compensation effect of feedforward control is fully exhibited by performing temperature compensation in consideration of the expansion and contraction of the gas amount due to changes in the temperature inside the furnace. It is possible to provide a furnace pressure control device that can optimize the feedback control gain, improve controllability, and prevent hunting and the like from occurring.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the reactor pressure control device according to the present invention, FIG. 2 is a block diagram showing another embodiment of the device of the present invention, and FIG. 3 is a block diagram of a conventional device. 20...Furnace, 21...Combustion medium supply means, 22...
・Furnace inflow gas amount acquisition means, 23... Temperature correction coefficient acquisition means, 24... Furnace pressure adjustment means, 25... Temperature correction means, 26... Combustion burner, 29... Fuel flow rate Detector, 30... Air flow rate detector, 31... Addition synthesis section, 32... Furnace temperature detector, 33... Square root calculation section, 3
4... Furnace pressure detector, 35... Furnace pressure regulator, 36.
... Operating end, 37... Feedforward control amount calculation means, 38... Feedforward model, 39...
- Addition calculation section, 41...gain correction means. Applicant's agent Patent attorney Takehiko Suzue TS3 diagram

Claims (3)

[Claims] (1) In a furnace pressure control device that outputs a furnace pressure adjustment signal to adjust the amount of gas flowing out of the furnace to be equal to the amount of gas flowing into the furnace based on the detected pressure inside the furnace using a furnace pressure regulator, An inflow gas amount acquisition means that detects the fuel flow rate and air flow rate to obtain the inflow gas amount into the furnace, and a furnace temperature detector is attached to the furnace, and temperature correction is performed based on the temperature detected in the furnace from the furnace temperature detector. a temperature correction coefficient obtaining means for obtaining a coefficient; and obtaining a temperature compensation signal using the temperature correction coefficient from the temperature correction coefficient obtaining means;
A furnace pressure control device characterized by comprising: temperature correction means for adding this temperature compensation signal to the furnace pressure adjustment signal to obtain an operation signal for operating an operation end of an amount of gas flowing out of the furnace. (2) The temperature correction means includes a feedforward control amount calculation means for calculating a feedforward control amount by multiplying the amount of gas flowing into the furnace by the temperature correction coefficient and the feedforward coefficient, and an output of the feedforward control amount calculation means. and means for obtaining a disturbance compensation signal as the temperature correction signal through a feedforward model; and means for providing a disturbance compensation signal to the furnace pressure adjustment signal to obtain an operation signal. Furnace pressure control device as described in section. (3) The temperature correction means includes a feedforward control amount calculation means for calculating a feedforward control amount by multiplying the amount of gas flowing into the furnace by the temperature correction coefficient and the feedforward coefficient, and an output of the feedforward control amount calculation means. means for obtaining a disturbance compensation signal as the temperature correction signal via a feedforward model, and feedback control based on the furnace pressure adjustment signal from the furnace pressure regulator and the temperature correction coefficient from the temperature correction coefficient acquisition means. 2. A reactor pressure control system according to claim 1, comprising gain modifying means for modifying the gain, and means for applying a disturbance compensation signal to the output of the gain modifying means to obtain an operation signal.