JP3020328B2 - Flow control method in mixing ratio control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a mixing ratio control device for controlling the calorific value as a fuel gas by mixing butane gas and air at an appropriate ratio, or a combustion burner applied to a heating furnace or the like. The present invention relates to a flow control method in a combustion control device and the like including the same. In the following, a flow control method in a combustion control device will be mainly described to facilitate understanding of the present invention.

[0002]

2. Description of the Related Art Conventionally, a heating furnace is provided with a burner for combustion, and a fuel line and an air line are connected to the burner, and each line is provided with a valve opening / closing drive motor and a valve opening degree sensor. A variable throttle mechanism, sensors such as a pre-valve pressure sensor and a differential pressure sensor, and an arithmetic controller connected to these sensors and a valve opening / closing drive motor are provided.

[0003] The combustion control of the combustion burner in such a heating system is carried out by an arithmetic and control unit in advance by controlling the flow coefficient with respect to the opening degree of the variable throttle mechanism in each of the fuel system and air system pipes, and the variable throttle mechanism and the combustion system. The relationship between the pressure and the flow rate between the burner and the like are stored, and based on the relationship and the signal from the pre-valve pressure sensor, and the flow rate set value that is separately determined and input to the arithmetic and control unit, it is moment by moment. The opening degree required for the variable throttle mechanism is obtained, and fuel and air are supplied to each burner from each pipe and burned.

[0004]

In the combustion control of the combustion burner described above, when the combustion state (furnace temperature) is changed, or when the furnace temperature is greatly increased or decreased, the fuel flow rate is changed. Attempts are made to control the opening of the variable throttle mechanism in both the fuel and air lines so that the air ratio is kept constant, but the operation is controlled every moment. In some cases, the opening cannot be fully controlled in combination with the driving speed capability of the driving motor, and the flow ratio (air ratio) between fuel and air is greatly disturbed.

When the flow rate ratio is disturbed as described above,
Problems such as soot generation due to incomplete combustion occur for the furnace.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to change the combustion state without significantly disturbing the flow rate ratio between fuel and air, or to increase the temperature in the furnace or to increase the temperature in the furnace. An object of the present invention is to provide a flow control method in a combustion control device that can cope with a temperature drop.

[0007]

In order to achieve the above object, a flow control method in a combustion control apparatus according to the present invention comprises a combustion burner in which a fuel pipe and an air pipe are connected and a flow coefficient is known. A variable throttle mechanism, a valve front pressure sensor, a fluid temperature sensor, and a valve opening / closing drive motor and a valve opening sensor of the variable throttle mechanism, and a valve front pressure sensor and a fluid temperature sensor. A control method for a combustion control device, comprising: an arithmetic controller connected to (a), a: measuring a valve front pressure, a fluid temperature, and a valve opening degree in each pipe by each sensor; and b: valve opening. The upper limit opening and the lower limit opening that can be reached within one calculation time in terms of the performance of the valve opening / closing drive motor are obtained from the valve opening measured by the degree sensor for each calculation, and the fuel and air at these upper and lower limits are determined. Obtaining flow coefficients of the respective variable throttle mechanisms; c: based on the flow coefficients, the fuel and air corresponding to the upper and lower limits of opening under the conditions of the pressure and temperature measured in a. Determining each flow rate; d: determining whether the flow rate of the fuel system requested to be set is within the upper / lower limit flow rate range determined in c); and e: out of the range in d. When it is determined that there is, the next lower limit flow rate is set to the next lower limit flow rate as the next fuel setting request flow rate; and f: it is determined to be out of the range by the above d and the next fuel setting request flow rate is made by the above e. A step of obtaining a required set flow rate of the air system corresponding to the corrected required fuel set flow rate from the required air ratio setting value and the theoretical air amount required for combustion, and g: obtained by f. Air system setting request Determining whether the amount falls within the upper / lower limit flow rate range obtained in the above c; and h: when determining that the flow rate is out of the range in the above g, the limit flow rate which is closer to the upper or lower limit flow rate. Is the next required air setting flow rate; and i: when it is determined that the flow rate is out of the range in g and the next required air setting flow rate is corrected in h, the fuel system corresponding to the corrected required air setting flow rate Determining the set required flow rate from the set required air ratio and the theoretical air amount required for combustion.

[0008]

According to the present invention, an upper limit opening and a lower limit opening that can be reached within one calculation time are obtained from the valve opening measured by the valve opening sensor at every calculation time in view of the performance of the valve opening / closing drive motor. The respective flow rates of fuel and air corresponding to these upper and lower opening degrees are obtained, and the upper and lower flow rate ranges, the set required flow rate of the fuel separately set, or the set required air ratio and the theoretical air amount required for combustion are determined. And the set required flow rate of the air corresponding to the set required flow rate of the fuel determined from
If the set required flow rate is out of the upper and lower flow rate range,
The next lower limit flow rate is set as the lower limit flow rate which is closer to the upper or lower limit flow rate, and when the upper limit or lower limit flow rate is adopted in this way, calculation is performed from the set required air ratio and the theoretical air amount required for combustion. , The flow rate ratio (air ratio) between fuel and air can be controlled in a substantially constant state without greatly disturbing the fuel / air flow rate. Combustion can be performed with incomplete combustion prevented.

Further, as described above, when the set required flow rate of the fuel or air is out of the upper and lower limit flow rate ranges, the limit flow rate closer to the upper or lower limit flow rate is set as the next set required flow rate. Disturbance in the flow rate ratio during the transition transition period can be minimized.

[0010]

Embodiments of the present invention will be described below. FIG.
It is a conceptual diagram when the combustion control method of the combustion burner according to the present invention is applied to a heating device, where a is an overall view and b is a view.
FIG. 3 is an enlarged view of the vicinity of a combustion burner of FIG.

In the drawing, reference numeral 1 denotes a fuel supply line,
The fuel supply line 1 is connected to a fuel supply source such as a gas fuel such as LPG.

Reference numeral 2 denotes a combustion air supply pipe, which is connected to a combustion air supply source such as a blower and a preheating air equipment (not shown).

Reference numeral 3 denotes a heating device, which refers to a continuous heating furnace, a batch furnace, an annealing furnace, or the like for heating an object to be heated.

Reference numeral 4 denotes a temperature controller (TIC). The temperature controller 4 is a controller (a general PID control type TIC or the like) for measuring and controlling the furnace temperature of the heating device 3. When the inside of the furnace is zone-controlled, it is provided for each temperature control zone.

Reference numeral 5 denotes an in-furnace temperature measurement sensor for measuring a process value (PV) for a temperature controller of the heating device 3 for each temperature control zone. Provided.

Reference numeral 6 denotes an arithmetic controller, which is an arithmetic controller for controlling the fuel and combustion air flow rate for each burner of the combustion burner 12, which will be described later. The burner 6 employs the combustion control method of the present invention so that accurate flow rate ratio (air ratio) control and flow rate measurement can be performed.

Reference numeral 7 denotes a fluid temperature measurement sensor which measures the fluid temperature of fuel gas and combustion air, which are control fluids, and is operated inside the operation controller 6. This is for measuring data used for temperature compensation calculation.

Reference numeral 8 denotes a pre-valve pressure sensor which measures the pre-valve pressure of the flow rate control valve 11 described later. By this measurement, the flow characteristic (opening and flow coefficient) is determined in advance. ) Is controlled to control the opening of the flow control valve 11. As a result, the valve opening required for controlling the target flow rate in consideration of the fixed flow coefficient of the combustion burner 12 is calculated in the arithmetic and control unit 6 to perform the opening control.

Reference numeral 9 denotes a valve opening / closing drive motor. The valve opening / closing drive motor 9 is equipped with a motor which is accurately operated to the relative movement opening (the amount of rotation of the motor) outputted from the arithmetic and control unit 6 in pulses. Further, an opening position measuring sensor (valve opening sensor) of the flow rate control valve 11 not shown is provided.

Reference numeral 10 denotes a pre-burner pressure sensor. The pre-burner pressure sensor 10 is controlled by a fluid temperature measurement sensor 7, a pre-valve pressure sensor 8, a valve opening / closing drive motor 9, and a combustion burner 12 described later. By comparing the measured flow rate with the fixed flow coefficient of the pre-burner pressure sensor 10 and the fixed flow coefficient of the combustion burner 12 and the flow rate measured by the fluid temperature measurement sensor 7, the fluid temperature measurement sensor 7,
Valve front pressure sensor 8, valve opening / closing drive motor 9, flow control valve 11
And an auxiliary sensor for automatically determining whether or not the combustion burner 12 is abnormal inside the arithmetic and control unit 6.

Reference numeral 11 denotes a flow control valve, which is a flow control valve.
Reference numeral 11 denotes a valve operated by the valve opening / closing drive motor 9 for adjusting the flow rate. At the same time, the characteristics of the opening degree and the flow coefficient are grasped and registered in the arithmetic and control unit 6 in advance so that the variable for measurement control can be obtained. It functions as a diaphragm mechanism (valueable orifice).

Reference numeral 12 denotes a combustion burner. The combustion burner 12 mixes fuel and combustion air, burns the mixture, and heats and raises the atmosphere in the furnace. Has a function as a fixed orifice for grasping a flow coefficient as a fixed throttle mechanism and calculating the inside of the calculation controller 6.

Next, a combustion control method in the above-described apparatus will be described step by step. The furnace temperature of each of the two zones A and B in the heating device 3 is measured by the furnace temperature measurement sensor 5 via the temperature controller 4, and the control output signal of the temperature controller 4 is transmitted to each of the zones A and B. B, while transmitting the pre-valve pressure, fluid temperature and valve opening in the fuel supply line 1 and the combustion air supply line 2 to the arithmetic and control unit 6 corresponding to B.
The temperature is measured by the fluid temperature measurement sensor 7, the valve front pressure sensor 8, and the opening position measurement sensor of the flow rate control valve 11, and the measurement signal is transmitted to the arithmetic and control unit 6.

Next, in the arithmetic and control unit 6, an upper limit opening and a lower limit opening which can be reached within one calculation time due to the performance of the valve opening / closing drive motor 9 are obtained from the measured valve opening by calculation. The flow coefficient of each flow control valve 11 of fuel and air at these upper and lower limits is obtained by calculation, and based on this flow coefficient, the upper and lower limits under the conditions of the measured pressure and temperature are calculated. The respective flow rates of the corresponding fuel and air are obtained by calculation.

Next, it is determined whether or not the flow rate of the fuel system, which has been separately determined and requested to be set, falls within the upper and lower flow rate ranges of the fuel obtained as described above. In addition to the fuel setting required flow rate, the air system setting required flow rate previously determined corresponding to the next fuel setting required flow rate is set as the next air setting required flow rate, and the valve opening corresponding to these flow rates is set to the valve opening / closing drive. Output to the motor 9 to control the flow rate of fuel and air.

On the other hand, when it is determined in the above determination that the flow rate is out of the range, the limit flow rate closer to the upper or lower flow rate is set as the next required fuel setting flow rate, and the air system setting demand corresponding to this fuel setting required flow rate is determined. The flow rate is calculated from the required air ratio setting value and the theoretical air amount required for combustion, and the calculated required flow rate of the air system is calculated according to the paragraph number [002].
It is determined whether the air is within the upper / lower flow rate range obtained in 4), and if it is within the range, the flow rate is set as the next required air setting flow rate, and the valve opening corresponding to these flow rates is set to the valve opening / closing drive motor 9. To control the flow rate of fuel and air.

On the other hand, when it is determined in the above determination that the flow rate is out of the range, the limit flow rate which is closer to the upper or lower flow rate is set as the next required air setting flow rate. Because of the deviation, the set required flow rate of the fuel system corresponding to this air set required flow rate was calculated again from the required air ratio setting value and the theoretical air amount required for combustion in the same manner as described above. The set required flow rate of the fuel system is set as the next required fuel set flow rate, and the valve opening corresponding to these flow rates is output to the valve opening / closing drive motor 9 to control the fuel and air flow rates.

Since the fuel and air flow rates are controlled and supplied to the combustion burner 12 as described above, the combustion can be performed with a substantially constant flow rate ratio (air ratio). Even when the temperature rises or falls, the variation in the flow rate can be reduced to change the combustion state.

The set required flow rate of air or fuel, which is corrected in the above-described embodiment, is different from the external demand of the fuel system flow rate satisfying the set required air ratio in the opening range which can be reached next time. The flow rate setting is the quickest, and the flow coefficient of the flow control valve 11 that matches the set required flow rate is calculated by the following relational expression. Qs = {Po × N ² × V ² / (N ² + V ² )} ^1/2 V (s) = {Qs ² × N ² / (Po × N ² −Qs ² )} ^1/2, where V ( s): Flow coefficient required for the variable throttle mechanism (flow control valve 11) V: Flow coefficient of the variable throttle mechanism (flow control valve 11) N: Fixed throttle flow coefficient Po: Supply measured by the pressure sensor 8 before the valve Pressure Qs: Set required flow rate

Based on the flow coefficient calculated above, a relational expression between the flow coefficient of the variable throttle system and the valve opening stored in the arithmetic and control unit 6 or a setting request by interpolation calculation or the like from a data table storing characteristics. Calculate the valve opening.

When one control operation time in the operation controller 6 becomes long, the operation amount calculated based on the previous measurement value by each sensor 5, 7, 8, etc. is output to the valve opening / closing drive motor 9. On the other hand, the operation based on the current measurement value may be performed in parallel with this operation. By doing so, one control operation time can be further reduced.

In the arithmetic and control unit 6, since the feedback control system is performed only for the valve opening and the flow control system is excluded from the feedback loop, the delay element of the flow control system is eliminated and a stable control system is constructed. it can.

In the above embodiment, the flow control valve
Although an example in which one combustion burner 12 is provided downstream of 11 has been described, the present invention is not limited to this, and a plurality of combustion burners 12 may be arranged in parallel downstream of the flow control valve 11. Good.

Although the above description has mainly been given of the flow rate control method in the combustion control device for easy understanding of the present invention, the present invention is not limited to the flow rate control method in the combustion control device. A mixing ratio control device for two fluids, for example, can be applied to flow rate control such as mixing ratio control when mixing butane gas and air at an appropriate ratio and controlling the calorific value as a fuel gas.

[0035]

As described above, when the mixing ratio control device is a combustion control device, according to the flow rate control method according to the present invention, when the combustion state is changed or when the combustion state is greatly changed, , Fuel and air flow ratio (air ratio)
The combustion control of the combustion burner can be performed at an almost constant flow rate ratio without largely disturbing the combustion. Thus, even when the combustion state is changed, incomplete combustion can be suppressed, and occurrence of soot and the like can be prevented.

When the set required flow rate of fuel or air is out of the upper and lower limit flow rate ranges, the limit flow rate which is closer to the upper or lower limit flow rate is set as the next set required flow rate.
Disturbance in the flow rate ratio during the transition period of the combustion state change can be minimized.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram when a combustion control method for a combustion burner according to the present invention is applied to a heating device, where a is an overall view and b is an enlarged view around the burner of a.

[Explanation of symbols]

1: Fuel supply line 2: Combustion air supply line
3: heating device 4: temperature controller 5: furnace temperature measurement sensor
6: Operation controller 7: Fluid temperature measurement sensor 8: Valve front pressure sensor 9: Valve opening / closing drive motor 10: Burner front pressure sensor 1
1: Flow control valve 12: Combustion burner A, B: Zone

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koji Nakagaki 2-4-7 Kyomachibori, Nishi-ku, Osaka-shi, Osaka Inside Chugai Furnace Industry Co., Ltd. (72) Inventor Yuzo Tanaka 2--4, Kyomachibori, Nishi-ku, Osaka-shi, Osaka No. 7 Inside Chugai Furnace Industry Co., Ltd. (72) Inventor Nakayasu Bin 4-10-11 Shomondori, Hirohata-ku, Himeji City, Hyogo Prefecture Inside Chugai Prox Co., Ltd. 4-10-11 Shomon-dori Chugai Prox Co., Ltd. Incubation Center (56) References JP-A-63-273724 (JP, A) JP-A-61-191840 (JP, U) JP-B-60-14973 (JP) , B2) (58) Field surveyed (Int.Cl. ⁷ , DB name) F23N 1/02 F23N 1/02 101 F23N 5/18

Claims (3)

(57) [Claims] 1. A fixed throttle mechanism in which an A fluid line and a B fluid line are connected and whose flow coefficient is known, a variable throttle mechanism, a pre-valve pressure sensor, and a fluid temperature sensor disposed in each of the fluid lines. And a calculation controller connected to a valve opening / closing drive motor and a valve opening degree sensor of the variable throttle mechanism, and a pre-valve pressure sensor and a fluid temperature sensor. A flow rate control method in a mixing ratio control device that mixes by: a: a step of measuring a valve front pressure, a fluid temperature, and a valve opening degree in each pipe line by each sensor; and b: each operation by a valve opening degree sensor. The upper limit opening and the lower limit opening that can be reached within one calculation time in terms of the performance of the valve opening / closing drive motor are obtained from the valve opening measured at the same time. coefficient C: obtaining the respective flow rates of the two fluids corresponding to the respective upper and lower opening degrees under the conditions of the pressure and the temperature measured in a, based on the flow coefficient, d: setting request Determining whether the flow rate of the fluid A is within the upper / lower limit flow rate range obtained in the above c; and e: when it is determined in the above d that the flow rate is out of the range, the upper or lower flow rate. Setting the limit flow rate closer to the next to the next required set flow rate of the fluid A; and f: if the d is determined to be out of the range and the set required flow rate of the next fluid A is corrected by the above e, the corrected flow rate is corrected. A
A step of obtaining a set required flow rate of the B fluid corresponding to the set required flow rate of the fluid, and a set required flow rate of the B fluid from the required mixture ratio setting value; Determining whether or not the flow rate falls within the upper / lower flow rate range obtained in step h; and, when determining that the flow rate is out of the range, the lower limit flow rate, which is closer to the upper or lower limit flow rate, is used for the next B fluid. And i: when the determined required flow rate of the next B fluid is corrected according to h and the determined required flow rate is determined to be out of the range by the above g, the corrected B
Obtaining a set required flow rate of fluid A corresponding to the set required flow rate of the fluid from the required mixture ratio setting value. 2. A fixed throttle mechanism having a known flow coefficient,
The flow control method according to claim 1, further comprising a mixing mechanism having a known flow coefficient. 3. A combustion burner in which a fuel pipe and an air pipe are connected and whose flow coefficient is known, a variable throttle mechanism, a valve front pressure sensor, a fluid temperature sensor, and a variable throttle mechanism provided in each of the pipes. Valve opening / closing drive motor of variable throttle mechanism and valve opening degree sensor,
A flow control method in a combustion control device further comprising: an arithmetic controller connected to a valve front pressure sensor and a fluid temperature sensor, wherein: a: a valve front pressure, a fluid temperature, and a valve opening degree in each pipe line; And b: determining an upper limit opening and a lower limit opening that can be reached within one calculation time in terms of the performance of the valve opening / closing drive motor from the valve opening measured at each calculation by the valve opening sensor, Determining the flow coefficient of each of the variable throttle mechanisms for fuel and air at these upper and lower limit opening degrees; and c: based on the flow coefficient, the upper and lower limit opening under the conditions of the pressure and temperature measured in a. Determining the respective flow rates of fuel and air corresponding to the degree; d: determining whether the flow rate of the fuel system requested to be set is within the upper / lower limit flow rate range determined in the above c. And e: when it is determined in step d that the flow rate is out of the range, a flow rate that is closer to the upper or lower flow rate is set as the next required fuel setting flow rate. F: the flow rate is determined to be out of the range in step d. When the next required fuel setting flow rate is corrected by the above e, the required setting flow rate of the air system corresponding to the corrected required fuel setting flow rate is obtained from the required air ratio setting value and the theoretical air amount required for combustion. And g: determining whether or not the set required flow rate of the air system determined in f is within the upper and lower limit flow rate range determined in c, and h: determining that the flow rate is out of the range in g. Setting the next lower limit flow rate to the next lower limit flow rate as the next required air setting flow rate; and i: determining that the flow rate is out of the range in the above g and correcting the next required air setting flow rate in the above h. Fix this Flow rate control method in the combustion control apparatus characterized by comprising determining a setting request flow of the fuel system corresponding to the air setting the required flow rate, and a theoretical amount of air required for combustion and set required air ratio, a.