CN109579044B - Air-fuel ratio dynamic feedforward combustion control method for walking beam furnace - Google Patents
Air-fuel ratio dynamic feedforward combustion control method for walking beam furnace Download PDFInfo
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- CN109579044B CN109579044B CN201811329303.2A CN201811329303A CN109579044B CN 109579044 B CN109579044 B CN 109579044B CN 201811329303 A CN201811329303 A CN 201811329303A CN 109579044 B CN109579044 B CN 109579044B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N1/00—Regulating fuel supply
- F23N1/02—Regulating fuel supply conjointly with air supply
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2223/00—Signal processing; Details thereof
- F23N2223/34—Signal processing; Details thereof with feedforward processing
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2239/00—Fuels
- F23N2239/04—Gaseous fuels
Abstract
The invention relates to a dynamic feedforward combustion control method for the air-fuel ratio of a walking beam furnace, in the combustion control, in a combustion control system, a temperature controller adjusts the air and gas flow by a double-cross amplitude limiting controller and the air-fuel ratio setting through the comparison of the set temperature and the detected temperature and calculation processing, the gas heat value is detected in real time by an on-site gas heat value instrument, the air-fuel ratio is dynamically calculated, the calculated air-fuel ratio replaces the set air-fuel ratio, and the air and gas flow is readjusted before the air and the gas are combusted, so that the feedforward adjustment is realized. The advantages are that: the air-fuel ratio coefficient and the air excess coefficient of each section are automatically controlled. And adding the gas heat value parameter into the primary combustion model, so that the air-fuel ratio parameter is dynamically adjusted according to the actual value of the gas heat value, and the most effective utilization of the gas is ensured. The air-fuel ratio is always in a reasonable combustion state, and finally, the energy consumption is reduced, and the unit consumption of coal gas is reduced.
Description
Technical Field
The invention belongs to the field of air-fuel ratio control, and particularly relates to an air-fuel ratio dynamic feedforward combustion control method for a walking beam furnace.
Background
The coal gas used in the hot rolling heating furnace procedure is the mixed coal gas of a coke oven, a blast furnace and a converter, the three kinds of coal gas are from iron making and steel making, and due to the difference of production and operation plans in each month, the generation proportion and the distribution mode of the three kinds of coal gas in each month are different, so that the heat value of the mixed coal gas fluctuates in a certain range. The fluctuation of the gas heat value is very unfavorable for controlling the unit consumption of the heating furnace gas, because the gas with different heat values can consume corresponding air quantity to ensure that the utilization rate of the mixed gas can reach the highest. If the air quantity is too small, incomplete combustion will occur, unburned coal gas will leave the hearth and enter the flue, so that energy waste is caused, and the flue and internal equipment thereof are easily damaged; if the air is excessive, the excessive air can take away the heat in the hearth, the combustion temperature is reduced, an oxidizing atmosphere is formed in the furnace, and the burning loss is increased.
Based on the above problems, the fluctuation problem of the gas heat value must be considered in the combustion control process of the heating furnace. However, in practical operation, under the condition that the gas heat value fluctuates frequently, the operator is difficult to perform prejudgment and adjustment in time, so that the air-fuel ratio is always in an imbalance state, the energy consumption is increased, and the gas unit consumption index is increased.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a dynamic feedforward combustion control method for the air-fuel ratio of a walking beam furnace, which automatically adjusts the air-fuel ratio according to the change of the gas calorific value to achieve the optimal combustion effect.
In order to achieve the purpose, the invention is realized by the following technical scheme:
a stepping heating furnace air-fuel ratio dynamic feedforward combustion control method, in the combustion control system, the temperature controller adjusts the air and gas flow by the comparison of the set temperature and the detected temperature through calculation processing, and the double-cross amplitude limiting controller and the air-fuel ratio setting, the gas heat value is detected in real time through the field gas heat value instrument, the air-fuel ratio is dynamically calculated, the calculated air-fuel ratio replaces the set air-fuel ratio, the air and gas flow is readjusted before the air and gas are combusted, and the feedforward adjustment is carried out;
the method for detecting the gas calorific value in real time and calculating the air-fuel ratio according to the field gas calorific value instrument comprises the following steps:
in formula (1): l is the air-fuel ratio, and the air quantity is set according to the L value and the actual quantity of the coal gas;
alpha is a heat value control weight coefficient, and the value of alpha is 0-1;
KmeasuringIs the actually measured gas heat value by a gas heat value instrument;
delta I is the air excess coefficient of each section, and the value range is 0.9-1.5;
K0is the theoretical coal gas heat value when the heating furnace is designed;
Lnis the theoretical air-fuel ratio at the time of furnace design.
Compared with the prior art, the invention has the beneficial effects that:
the invention improves the existing combustion control model, and the added air-fuel ratio coefficient and the air excess coefficient of each section are automatically controlled. And adding the gas heat value parameter into the primary combustion model, so that the air-fuel ratio parameter is dynamically adjusted according to the actual value of the gas heat value, and the most effective utilization of the gas is ensured. In the automatic mode, the air-fuel ratio is always in a reasonable combustion state, and finally, the energy consumption is reduced, the unit consumption of coal gas is reduced, and the atmospheric pollution caused by insufficient combustion is reduced.
Drawings
Fig. 1 is a control flow chart of the present invention.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings, but it should be noted that the present invention is not limited to the following embodiments.
Referring to fig. 1, in a combustion control system, a temperature controller adjusts air and gas flow rates by a double-cross amplitude limiting controller and air-fuel ratio setting through comparison of set temperature and detected temperature and calculation processing, detects gas heat value in real time through an on-site gas heat value instrument, dynamically calculates the air-fuel ratio, replaces the set air-fuel ratio by the calculated air-fuel ratio, and readjusts the air and gas flow rates before air and gas are combusted to implement feed-forward regulation;
the method for detecting the gas calorific value in real time and calculating the air-fuel ratio according to the field gas calorific value instrument comprises the following steps:
in formula (1): l is the air-fuel ratio, and the air quantity is set according to the L value and the actual quantity of the coal gas;
alpha is a heat value control weight coefficient, and the value of alpha is 0-1;
KmeasuringIs the actually measured gas heat value by a gas heat value instrument;
delta I is the air excess coefficient of each section, and the value range is 0.9-1.5;
K0is the theoretical coal gas heat value when the heating furnace is designed;
Lnis the theoretical air-fuel ratio at the time of furnace design.
Examples
The dynamic feedforward combustion control method of the air-fuel ratio of the walking beam type heating furnace is based on the parallel cascade double-crossing amplitude limiting combustion control, except that the air-fuel ratio is measured at any time and corrected in time; the method is a feed-forward control, when the heat value of the fuel gas changes, the air-fuel ratio is timely changed to compensate before the combustion is not influenced, and therefore the combustion can be really reasonable. The real-time monitoring value is obtained through a field heat value instrument, and the real-time monitoring value is calculated through a formula and then is used as a parameter to participate in calculation.
In the system, links of measuring the heat value of the fuel gas and correcting and operating the air-fuel ratio are added. The air-fuel ratio correction value can be found by experience or calculation according to the magnitude of the fluctuation of the heat value. Since the correction operation occurs before the actual combustion, it can be compensated in time.
In formula (1): l is the air-fuel ratio, and the air quantity is set according to the L value and the actual quantity of the coal gas;
delta I is the air excess coefficient of each section, the values of the soaking section and the second heating section are 1.05, and the value of the first heating section is 1.02;
alpha is a heat value control weight coefficient, and the value of alpha is 0.65-0.75;
KmeasuringIs the actually measured gas heat value by a gas heat value instrument;
K0is the theoretical coal gas heat value when the heating furnace is designed; the heating furnace is implemented at 2000kcal
LnThe air-fuel ratio is a theoretical air-fuel ratio in the design of the heating furnace, and the implementation of the heating furnace is limited to 1.6453-2.0524.
Referring to fig. 1, in operation, the temperature controller adjusts the air and gas flow rate through the comparison of the set temperature and the detected temperature, calculation processing, and the double-crossover limiting controller and the air-fuel ratio setting. The double-cross amplitude limiting control uses a hearth temperature regulating loop as a main loop and gas flow and air flow as auxiliary loops to form a cascade double-cross amplitude limiting control system. The gas flow control device reduces adverse effects caused by the difference of hysteresis coefficients between a gas control loop and an air control loop by limiting the variation range of gas and air flow in a transition state, and has good control precision.
The invention adopts a gas heat value instrument to measure the gas heat value of a heating furnace gas main pipe. And adding the gas heat value parameter into the primary combustion model, so that the air-fuel ratio parameter is dynamically adjusted according to the actual value of the gas heat value, and the most effective utilization of the gas is ensured.
Claims (1)
1. A dynamic feedforward combustion control method for the air-fuel ratio of a stepping heating furnace is characterized in that in a combustion control system, a temperature controller adjusts the air and gas flow by a double-cross amplitude limiting controller and the air-fuel ratio setting through the comparison of the set temperature and the detected temperature and calculation processing, the gas heat value is detected in real time through an on-site gas heat value instrument, the air-fuel ratio is dynamically calculated, the calculated air-fuel ratio replaces the set air-fuel ratio, the air and gas flow is readjusted before the air and the gas are combusted, and feedforward adjustment is carried out;
the method for detecting the gas calorific value in real time and calculating the air-fuel ratio according to the field gas calorific value instrument comprises the following steps:
in formula (1): l is the air-fuel ratio, and the air quantity is set according to the L value and the actual quantity of the coal gas;
alpha is a heat value control weight coefficient, and the value of alpha is 0-1;
KmeasuringIs the actually measured gas heat value by a gas heat value instrument;
delta I is the air excess coefficient of each section, and the value range is 0.9-1.5;
K0is the theoretical coal gas heat value when the heating furnace is designed;
Lnis the theoretical air-fuel ratio at the time of furnace design.
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| CN201811329303.2A CN109579044B (en) | 2018-11-09 | 2018-11-09 | Air-fuel ratio dynamic feedforward combustion control method for walking beam furnace |
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| CN201811329303.2A CN109579044B (en) | 2018-11-09 | 2018-11-09 | Air-fuel ratio dynamic feedforward combustion control method for walking beam furnace |
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| KR100560114B1 (en) * | 2003-10-27 | 2006-03-13 | 한국생산기술연구원 | Method of automatic control for Multi combustion system with multiple air supply |
| CN101684944B (en) * | 2008-09-28 | 2011-07-20 | 宝山钢铁股份有限公司 | Self-optimizing combustion control method of blast-furnace hot blast stove |
| CN102654286B (en) * | 2012-05-18 | 2014-06-11 | 无锡龙山科技有限公司 | Intelligent dynamic combustion atmosphere controller |
| CN103062790B (en) * | 2012-12-29 | 2016-01-20 | 聚光科技(杭州)股份有限公司 | Heating furnace combustion control method |
| KR101464486B1 (en) * | 2013-05-31 | 2014-12-04 | 한국에너지기술연구원 | air-fuel ratio control a control apparatus and system depending on heating value change and a control method using it |
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