KR100560114B1 - Method of automatic control for Multi combustion system with multiple air supply - Google Patents

Abstract

The present invention searches in the direction of minimizing carbon monoxide and nitrogen oxides in the exhaust gas using an exhaust gas detection unit, and searches the optimum position information of each valve in the control panel with a search algorithm that finds such an optimal condition. 4-20mA analog signal is supplied to drive the valve, and the flow rate of the flow meter is transferred back to the computer through the control panel to monitor the flow rate, and the error range of the flow rate is used by the PID (Proportional Integral Derivative control algorithm). To correct the flow rate of the air. Through this series of processes, it is possible to optimally find the distribution ratio of the combustion air supplied to the stage and to supply the quantitative fuel and the combustion air as the oxidant.

Multistage, Combustion, Fuel, Air, Exhaust, Optimal, Automatic Control

Description

Method of automatic control for Multi combustion system with multiple air supply}

1 is a block diagram showing a multi-stage air supply combustion system according to the present invention;

2 is a conceptual diagram showing a route to find an optimal air distribution ratio using an automatic control method of a multistage air supply combustion system according to the present invention;

3 is a flowchart illustrating an automatic control method according to the present invention.

* Description of the symbols for the main parts of the drawings *

1: combustion chamber 3: multistage air supply combustor

5: exhaust gas detection unit 7: control unit

9: fuel supply unit 11: computer

13: control panel 15: valve

17 flow meter 19 pressure transducer

21 solenoid valve 23 pressure control panel

The present invention relates to an automatic control method for a multi-stage air supply combustion system, and more particularly, to an automatic control method for a multi-stage air combustion system capable of reducing carbon monoxide and nitrogen oxides generated during combustion.

In general, the multi-stage air supply combustion system has a method of performing optimal combustion by measuring the oxygen concentration in the combustion gas as in the Republic of Korea Registration No. 10-0328951.

Another type of multi-stage air supply combustion system is a method in which the flame in the combustion chamber is determined by the operator by directly viewing the visible shape of the flame or by directly measuring the exhaust gas to determine the operating conditions.

However, such a multi-stage air combustion system is quantitatively determined by the driver's visible and repetitive errors in determining the operating conditions of the combustor by directly determining the visible shape of the flame or determining the operating conditions after directly measuring the exhaust gas. In many cases, measurement is not possible.

The present invention has been proposed to solve the above problems, and to provide an automatic control method of a multi-stage air supply combustion system to maximize the combustion efficiency and to reduce the nitrogen oxide series of the exhaust gas constituents.

It is another object of the present invention to provide an automatic control method capable of maximizing the performance of a multi-stage air supply combustion system in a quasi-steady state.

Furthermore, the present invention provides an automatic control method capable of controlling in real time by continuously monitoring and optimizing the stability of combustion against the instability of combustion caused by disturbances in the range of operation beyond the limits of the actuator and the multi-stage air supply combustion system. There is.

In the method for automatically controlling the multistage air supply combustion system of the present invention for achieving the above technical problem, in the method for automatically controlling the multistage air supply combustion system comprising a discharge stage for discharging the exhaust gas burned in the combustion chamber, Setting a coordinate system for setting a coordinate system for moving optimal points in a two-dimensional vector space to detect one component included in the exhaust gas at an emission stage; In the step of setting the coordinate system, the step of setting the initial starting point P _o ^k and the unit vector u _r ^k for searching the direction in the two-dimensional vector space, and the point P ₀ ⁰ which is the initial starting point by the P _o ^k Stores the value of J ₀ , finds it at P ₀ ⁰ , then moves to the point P ₁ ¹ (P ₀ ⁰ + λ ₁ ⁰ u ₁ ⁰ ), which is the optimal value along u ₁ ^0, which is the best direction, and then P _point stores the value of J ₁ corresponding to the ^first and, P ₁ and then to find from the ¹ P to be an optimal value according to u ₂ ¹ an optimal direction ^{_{2 2 (P 1 1 + λ}} 2 1 u 2 1) Go to store the J ₂ value corresponding to P ₂ ^2, and then back to find the optimum value in the P ₂ ² does not find a greater J value than ^{_{P 2 2 u 1 0 + u}} 2 search in the ^first direction Starting with, finding an optimal value in this direction and moving to P ₃ ³ where J is maximum to find the optimal point J; Performing the step of repeating from the initial coordinate system setting step at the position of P ₃ ³ to storing the J value of P ₂ ² of finding the optimum point in the step of finding the optimum point; Automatic combustion is performed by adjusting the amount of fuel and the amount of air supplied to the combustion chamber.

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In the step of finding the optimum point, the direction of finding the optimum value is preferably made in three directions.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 1 shows a configuration diagram of a multi-stage air supply combustion system according to the present invention.

The present invention provides a multistage air supply combustor (3) installed at the lower end of the combustion chamber (1), and an exhaust gas detection unit (5) connected to the discharge end of the combustion chamber (1) and capable of detecting carbon monoxide and nitrogen oxides among the components of the exhaust gas. ), A control unit 7 connected to the exhaust gas detection unit 5, and a fuel supply unit 9 for supplying fuel to the combustion chamber 1.

Here, the exhaust gas detecting unit 5 sends the concentration value as a signal using an analog signal of 4-20 mA or a digital value having a concentration value in ppm as a signal as an optimal algorithm.

The signal detected by the exhaust gas detector 5 is input to the controller 7 connected to the exhaust gas detector 5.

The control unit 7 monitors the measured concentration value of the exhaust gas component and the amount of air supplied to the multi-stage air supply combustor 3 to set the optimum air distribution ratio, and the optimum air set in the computer 11. As a control panel 13 based on DSP (Digital Signal Processor) which can receive the distribution ratio and process the data faster than the general computer and input / output of the signal and send signal values of the valve and flowmeter to the computer 11. It is composed.

In addition, the control unit 7 is connected to the air supply line to control the plurality of valves 15 to adjust the flow rate of air at the optimum conditions, and the flow meter connected to the air supply line and corresponding to the plurality of valves 15 It further includes (17). The plurality of valves 15 and the flow meter 17 are connected to the control panel 13.

The plurality of valves 15 preferably use a valve operated as a proportional control valve that can determine the opening degree of the valve as an input signal of 4-20 mA. For example, a solenoid valve or a motor-driven valve may be used. Can be.

The flow meter 17 outputs an output signal of 4-20 mA depending on the flow rate.

The fuel supply unit 9 is connected to the multistage air supply combustor 3 to control the amount of fuel supplied to the multistage air supply combustor 3. The fuel supply unit 9 supplies fuel to the multistage air supply combustor 3 through a fuel supply line connected to the fuel container.

A pressure transducer 19 and a solenoid valve 21 are installed in the fuel supply line, and a fuel pressure control panel 23 is connected to the pressure transducer 19 and the solenoid valve 21.

The multi-stage air supply combustion system according to the present invention configured as described above is operated by an automatic control method to control the combustion in the combustion chamber 1 in real time to operate under optimum conditions.

In more detail, the exhaust gas detection unit 5 is used to search in the direction of minimizing carbon monoxide and nitrogen oxide in the exhaust gas, and the position of the optimum point by a searching algorithm that finds such an optimal condition. The control panel 13 transmits the information to each valve to provide a 4-20 mA analog signal to drive the valve, and transmits the flow rate of the flow meter 17 based on this to the computer 11 through the control panel 13 to monitor the flow rate. The error range of the flow rate is corrected by using a PID (Proportional Integral Derivative control algorithm). Through this series of processes, it is possible to optimally find the distribution ratio of the combustion air supplied to the stage and to supply the quantitative fuel and the combustion air as the oxidant.

An automatic control method for enabling the operation under such an optimum condition will be described with reference to FIGS. 2 and 3 as follows.

As shown in Figs. 2 and 3, the automatic control method starts with a coordinate system setting step.

That is, the automatic control method should set a coordinate system for moving the optimum points in the two-dimensional vector space before setting the direction of the vector. Therefore, whenever you move to the optimal value, you need to set the coordinate system. If you find the optimal point to move, you must set the coordinate system that uses the point as the origin.

Then, the process proceeds to the steps for setting up the unit vector u _r ^k to search for the zero point P _o ^k and orientation within the two-dimensional vector space. Here, the superscript k (k = 1… N) indicates a repetitive round and the subscript r indicates a search direction. The number of directions of the unit vector (r = 1, 2, 3) is set in three directions. Therefore, set the unit vector as follows.

The purpose of searching each direction as a one-dimensional unit vector is to determine a step length (λ _r ^k ) for obtaining a maximum value of a function value. The direction of the step length follows the direction of the unit vector but the magnitude is the same.

The step of finding the best point J then stores the J ₀ value corresponding to the point P ₀ ⁰ of the first round to start.

After searching in three directions from P ₀ ⁰ , move to P ₁ ¹ (P ₀ ⁰ + λ ₁ ⁰ u ₁ ⁰ ), which is the optimal value along u ₁ ^0, which is the best direction, and then P ₁ and stores the value of J ₁ corresponding to the ^first.

In addition, after then the search in three directions from the P ₁ ¹ along the u ₂ ¹ of the best direction, go to point ^{_{P 2 2 (P 1 1 +}} λ 2 1 u 2 1) that the optimum value P ₂ ² Store the corresponding J ₂ value.

Then, after you find the best value in three directions again at P _{² 2} J does not find a larger value than P _{² 2} Start the search with u ^{₁ 0} + u _{2 1} direction. If we find the best value in this direction, we move to P ₃ ³ where J ₃ is the maximum.

In the step of finding the optimal point, the process is repeated from the initial coordinate system setting step of P ₃ ³ to the process of storing the J ₂ value of P ₂ ² of the step of finding the optimum point.

This iterative and sequential method is used to optimize the air distribution ratio in the combustor 3 of the multistage air supply to a value that maximizes the performance index.

Therefore, the optimal point is defined as

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는 성능함수를 최대화하기 위해서 제시한 보조함수(sub-function)이고 NO_χ와 CO의 농도가 낮을 때와 연소 시스템의 효율이 높을 때 최대값을 가진다.here

Is a sub-function proposed to maximize the performance function and has a maximum value when the NO _χ and CO concentrations are low and the combustion system efficiency is high.

In all cases, a weighting factor given as a weight may be defined according to relative importance by the controller designer through a value output from the system, but is defined as the same input value in the present invention. 0.5 is given for two auxiliary functions and 0.33 for three. Each auxiliary function is defined as follows.

The air distribution ratio at the point where the J value found by the definition of the auxiliary function becomes the maximum is used as the optimal air distribution ratio.

Embodiments as described above are not intended to limit the rights of the present invention, it can be seen that it can be carried out through more various modifications.

As described above, according to the present invention, it is possible to automate the operation of the conventional multi-stage air supply combustor to enable more improved optimal combustion.

In addition, the optimum combustion conditions can be established in the shortest time since the optimum combustion is found using a computer and a control panel.

Furthermore, it is possible to quickly and accurately cope with variations in the constituents of the fuel supplied to the multistage air supply combustor and variations in the air supply.

In addition, it is possible to establish operating conditions of a system in which it is difficult to grasp fuel components such as an incinerator.

In addition, it is possible to increase combustion efficiency and reduce exhaust gas by controlling in real time and operating under optimum conditions.

Claims (2)

A method for automatically controlling a multistage air supply combustion system comprising an exhaust stage for discharging exhaust gas combusted in a combustion chamber, Setting a coordinate system for moving optimal points in a two-dimensional vector space to detect one component included in the exhaust gas at the discharge end; Setting an initial starting point P ₀ ^k and a unit vector u _r ^k for searching a direction in a two-dimensional vector space in setting the coordinate system; It stores the J ₀ value of the point P ₀ ⁰ , which is the initial starting point of the P ₀ ^k , finds it in P ₀ ⁰ , and then becomes the optimal value along the optimal direction u ₁ ⁰ (P ₁ ¹ (P ₀ ^0). + λ ₁ ⁰ u _1, go to ⁰⁾ stores the value of J ₁ corresponding to P ₁ ^1, and, P ₁ and then to find from the ¹ P is the optimal value in accordance with the u ₂ ¹ the optimal orientation ^{_{22 (P 1 1 + λ 2 1}} u 2 1) to move to the point, save the J ₂ value corresponding to P ₂ ^2, and again to find the optimum value in the P ₂ ² greater J value than P ₂ ² If it is not found, start searching in the u ₁ ⁰ + ₂ ¹ direction, and if the optimum value is found in this direction, J moves to P ₃ ³ where J is the maximum to find the optimum point J; Performing the step of repeating from the initial coordinate system setting step at the position of P ₃ ³ to storing the J value of P ₂ ² of finding the optimum point in the step of finding the optimum point; An automatic control method for a multi-stage air supply combustion system for performing automatic combustion by adjusting the amount of fuel and the amount of air supplied to the combustion chamber. The method of claim 1, wherein in the step of finding the optimum point, the direction of finding the optimum value is three directions.

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