阅读说明：本技术 一种空燃比可调的蓄热式单烧嘴熔铝炉燃烧控制方法 (Combustion control method of heat accumulating type single-burner aluminum melting furnace with adjustable air-fuel ratio ) 是由 谭连元 李翼 唐光麒 王永机 田翔 田鹏 于 2019-09-26 设计创作，主要内容包括：本发明提供一种空燃比可调的蓄热式单烧嘴熔铝炉燃烧控制方法,该方法根据实时检测的炉膛温度和燃气流量来控制燃气流量调节阀中燃气进入蓄热式单烧嘴熔铝炉的燃气流量；根据实时检测的炉膛温度、排烟温度、助燃风温度和燃气温度得到实时的空燃比,或者根据蓄热式单烧嘴熔铝炉的燃烧阶段和燃烧模式设定空燃比；再根据空燃比和实时检测的助燃空气流量来控制助燃空气流量调节阀中助燃空气进入蓄热式单烧嘴熔铝炉的空气流量,实现燃气流量与空气流量实时控制调节,以提高蓄热式单烧嘴熔铝炉的燃烧热效率。本发明控制方法可实现空燃比自动可调,使系统能更好地适应不同燃烧阶段熔铝炉燃烧特性的变化,达到节能降耗及提高熔铝品质的目的。(The invention provides a combustion control method of a heat accumulating type single-burner aluminum melting furnace with an adjustable air-fuel ratio, which is characterized in that the method controls the gas flow of gas in a gas flow regulating valve into the heat accumulating type single-burner aluminum melting furnace according to the real-time detected hearth temperature and the gas flow; obtaining a real-time air-fuel ratio according to the real-time detected hearth temperature, the real-time detected exhaust gas temperature, the real-time detected combustion air temperature and the real-time detected fuel gas temperature, or setting the air-fuel ratio according to the combustion stage and the combustion mode of the heat accumulating type single-burner aluminum melting furnace; and controlling the air flow of the combustion air in the combustion air flow regulating valve into the heat accumulating type single-burner aluminum melting furnace according to the air-fuel ratio and the combustion air flow detected in real time, so as to realize the real-time control and regulation of the gas flow and the air flow and improve the combustion heat efficiency of the heat accumulating type single-burner aluminum melting furnace. The control method can realize automatic adjustment of the air-fuel ratio, so that the system can better adapt to the change of the combustion characteristics of the aluminum melting furnace in different combustion stages, and the aims of saving energy, reducing consumption and improving the quality of molten aluminum are fulfilled.)

1. A combustion control method of a heat accumulating type single-burner aluminum melting furnace with an adjustable air-fuel ratio is characterized by comprising the following steps:

Controlling the gas flow of gas in the gas flow regulating valve into the heat accumulating type single-burner aluminum melting furnace according to the real-time detected hearth temperature and the gas flow;

obtaining a real-time air-fuel ratio according to the real-time detected hearth temperature, the real-time detected exhaust gas temperature, the real-time detected combustion air temperature and the real-time detected fuel gas temperature, or setting the air-fuel ratio according to the combustion stage and the combustion mode of the heat accumulating type single-burner aluminum melting furnace; and controlling the air flow of the combustion air in the combustion air flow regulating valve into the heat accumulating type single-burner aluminum melting furnace according to the air-fuel ratio and the combustion air flow detected in real time, so as to realize the real-time control and regulation of the gas flow and the air flow and improve the combustion heat efficiency of the heat accumulating type single-burner aluminum melting furnace.

2. The combustion control method of the heat accumulating type single burner aluminum melting furnace with the adjustable air-fuel ratio as claimed in claim 1, characterized in that: setting initial hearth temperature and initial gas flow; the initial hearth temperature and the real-time detected hearth temperature are used as input quantities of a furnace temperature control unit to obtain a hearth temperature control quantity; the hearth temperature control quantity, the initial gas flow and the gas flow detected in real time are used as input quantities of a gas flow control unit, and the gas flow of gas in a gas flow control valve entering the heat accumulating type single-burner aluminum melting furnace is controlled through a gas flow control unit.

3. the combustion control method of the heat accumulating type single burner aluminum melting furnace with the adjustable air-fuel ratio as claimed in claim 1, characterized in that: setting an initial air flow rate; the real-time detected hearth temperature, the smoke exhaust temperature, the combustion air temperature and the fuel gas temperature are used as input quantities of an air-fuel ratio control unit to obtain a real-time air-fuel ratio; the air-fuel ratio, the initial air flow and the air flow detected in real time are used as input quantities of an air flow control unit, and the air flow control unit is used for controlling the air flow of combustion air in a combustion air flow regulating valve into the heat accumulating type single-burner aluminum melting furnace.

4. The combustion control method of the heat accumulating type single burner aluminum melting furnace with the adjustable air-fuel ratio as claimed in claim 1, characterized in that: the setting of the air-fuel ratio according to the combustion stage and the combustion mode of the heat accumulating type single-burner aluminum melting furnace is as follows: in a working interval which is usually set by a heat accumulating type single-burner aluminum melting furnace, the optimal air-fuel ratio is determined by taking the fastest temperature rise as a target or according to the flame characteristics of a hearth, and the optimal air-fuel ratio is taken as the set air-fuel ratio.

5. The combustion control method of the heat accumulating type single burner aluminum melting furnace with the adjustable air-fuel ratio as claimed in claim 1, characterized in that: the setting of the air-fuel ratio according to the combustion stage and the combustion mode of the heat accumulating type single-burner aluminum melting furnace is as follows: selecting an optimal air-fuel ratio as an initial air-fuel ratio, and setting an upper temperature limit set value; and performing combustion control by using the optimal air-fuel ratio, and gradually changing the air-fuel ratio when the temperature reaches the upper temperature limit set value to finally determine the set air-fuel ratio.

6. The combustion control method of the heat accumulating type single burner aluminum melting furnace with the adjustable air-fuel ratio as claimed in claim 1, characterized in that: the setting of the air-fuel ratio according to the combustion stage and the combustion mode of the heat accumulating type single-burner aluminum melting furnace is as follows: and in an experience database of the work of the heat accumulating type single-burner aluminum melting furnace, searching numerical values corresponding to the combustion stage and the combustion mode of the heat accumulating type single-burner aluminum melting furnace to calculate the air-fuel ratio, wherein the air-fuel ratio is used as the set air-fuel ratio.

7. The combustion control method of the heat accumulating type single burner aluminum melting furnace with the adjustable air-fuel ratio as claimed in claim 1, characterized in that: and a furnace temperature measuring thermocouple is arranged on the side wall of the middle part of the heat accumulating type single-burner aluminum melting furnace so as to detect the hearth temperature of the heat accumulating type single-burner aluminum melting furnace in real time.

8. The combustion control method of the heat accumulating type single burner aluminum melting furnace with the adjustable air-fuel ratio as claimed in claim 1, characterized in that: and a smoke discharge temperature thermocouple is arranged at the smoke discharge position at the top of the heat accumulating type single-burner aluminum melting furnace so as to detect the smoke discharge temperature of the heat accumulating type single-burner aluminum melting furnace in real time.

9. The combustion control method of the heat accumulating type single burner aluminum melting furnace with the adjustable air-fuel ratio as claimed in claim 1, characterized in that: a combustion-supporting fan and an air supply pipeline are arranged, and the combustion-supporting fan is connected with the heat accumulating type single-burner aluminum melting furnace through the air supply pipeline; the combustion air flow regulating valve is arranged on the air supply pipeline; and a combustion-supporting air temperature thermocouple is also arranged on the air supply pipeline so as to detect the temperature of combustion-supporting air entering the heat accumulating type single-burner aluminum melting furnace in real time.

10. The combustion control method of the heat accumulating type single burner aluminum melting furnace with the adjustable air-fuel ratio as claimed in claim 1, characterized in that: arranging a fuel gas supply device and a fuel gas supply pipeline, wherein the fuel gas supply device is connected with the heat accumulating type single-burner aluminum melting furnace through the fuel gas supply pipeline; the gas flow regulating valve is arranged on the gas supply pipeline; and a thermocouple for measuring the gas temperature is also arranged on the gas supply pipeline so as to detect the temperature of the gas entering the heat accumulating type single-burner aluminum melting furnace in real time.

Technical Field

The invention relates to the technical field of combustion control, in particular to a combustion control method of a heat accumulating type single-burner aluminum melting furnace with an adjustable air-fuel ratio.

Background

The aluminum alloy smelting and casting are main energy consumption processes in the aluminum processing industry, and the energy consumption of the aluminum alloy smelting and casting accounts for about 60 percent of that of the aluminum production process; how to realize energy conservation and emission reduction by improving the existing production process and equipment has important significance for realizing green low-carbon economy in the aluminum processing industry.

Common energy-saving measures of the existing aluminum melting furnace are as follows:

1) Technological improvement, such as shortening and optimizing the fusion casting technological process.

2) And the heat accumulating type burners and other advanced burners are adopted, so that waste heat resource recovery is realized, and the smoke exhaust temperature is reduced.

3) The high-standard refractory material is selected, so that the heat exchange area is increased, and the heat dissipation loss of the wall body of the aluminum melting furnace is reduced.

4) And a heat exchanger is additionally arranged or a flue gas waste heat cascade utilization system is additionally arranged to realize waste heat recovery.

5) the excess air ratio of the aluminum melting furnace is controlled by adopting a more advanced mode such as automatic adjustment of the fuel-air ratio, so that the heat loss of exhaust smoke caused by excessive air quantity and the heat loss of incomplete combustion of fuel caused by insufficient air quantity are reduced.

In the above energy saving measures, the automatic fuel-air ratio adjusting technology is directly related to the heat efficiency of the aluminum melting furnace, and represents the level of automation of an aluminum processing enterprise.

At present, in the smelting equipment in the industry of aluminum profile extrusion forming products, a traditional combustion control system usually adopts a pressure balance (pressure equalizing) mode, and the defects are as follows:

1) Since only the pressure is controlled, there is a possibility that it does not match the combustor.

2) The adjustable range of the burner air to gas flow ratio is limited.

3) And the control precision is lower and the repeatability is poor during adjustment.

4) When using preheated air, temperature correction cannot be performed (i.e., the air to gas flow ratio cannot be adjusted).

5) Once the combustion characteristics of the aluminum melting furnace are changed, accurate control cannot be realized.

Therefore, the traditional fixed air-fuel ratio control mode cannot ensure higher thermal efficiency in the whole combustion process.

Disclosure of Invention

The invention aims to overcome the defects and shortcomings in the prior art and provide a combustion control method of a heat accumulating type single-burner aluminum melting furnace with an adjustable air-fuel ratio.

In order to achieve the purpose, the invention is realized by the following technical scheme: a combustion control method of a heat accumulating type single-burner aluminum melting furnace with an adjustable air-fuel ratio is characterized by comprising the following steps:

Controlling the gas flow of gas in the gas flow regulating valve into the heat accumulating type single-burner aluminum melting furnace according to the real-time detected hearth temperature and the gas flow;

Obtaining a real-time air-fuel ratio according to the real-time detected hearth temperature, the real-time detected exhaust gas temperature, the real-time detected combustion air temperature and the real-time detected fuel gas temperature, or setting the air-fuel ratio according to the combustion stage and the combustion mode of the heat accumulating type single-burner aluminum melting furnace; and controlling the air flow of the combustion air in the combustion air flow regulating valve into the heat accumulating type single-burner aluminum melting furnace according to the air-fuel ratio and the combustion air flow detected in real time, so as to realize the real-time control and regulation of the gas flow and the air flow and improve the combustion heat efficiency of the heat accumulating type single-burner aluminum melting furnace.

The furnace temperature control of the aluminum melting furnace mainly comprises the control of gas flow and air flow. The air-fuel ratio is an important parameter of the heating equipment, and has great influence on exhaust emission, thermal efficiency and economic performance. Insufficient air flow can cause insufficient combustion of fuel gas, and waste of energy is caused; and if the air flow is too large, the air can be fully combusted, but a large amount of heat can be taken away by redundant air, and energy waste can also be caused. In order to obtain the maximum combustion efficiency of the aluminum melting furnace, the air-fuel ratio needs to be controlled within a reasonable range.

In the conventional proportional control method, an operator sets a fixed air-fuel ratio according to the common sense and experience of operation; in the combustion stage of the aluminum melting furnace, the control system can automatically control the opening of the air regulating valve and the gas regulating valve according to the temperature of the hearth or the flue gas. The disadvantage of this control method is that the opening ratio of the air regulating valve and the gas regulating valve is kept fixed during the combustion process, and the flexibility is poor. In fact, the aluminum melting furnace has the characteristics of multi-coupling and strong nonlinearity, and uncertain factors such as gas pressure and heat value which influence the combustion characteristics of the aluminum melting furnace are numerous, so that the control mode of the fixed air-fuel ratio cannot ensure higher thermal efficiency in the whole combustion process.

In the scheme, the air-fuel ratio adjustable combustion control mode is adopted, the air-fuel ratio is changed in real time according to the change conditions of the preheating temperature, namely the temperature of combustion-supporting air, the temperature of fuel gas, the temperature of a hearth and the temperature of exhaust smoke, and the air-fuel ratio is used as one of the input quantities of the air flow control unit to control and adjust the output quantity of the combustion-supporting air in the combustion-supporting air flow regulating valve entering the heat accumulating type single-burner aluminum melting furnace, so that the system can better adapt to the change of the combustion characteristics of the aluminum melting furnace in different combustion stages, the purposes of saving energy, reducing consumption and improving the quality of molten aluminum are achieved, and the.

Specifically, setting an initial hearth temperature and an initial gas flow; the initial hearth temperature and the real-time detected hearth temperature are used as input quantities of a furnace temperature control unit to obtain a hearth temperature control quantity; the hearth temperature control quantity, the initial gas flow and the gas flow detected in real time are used as input quantities of a gas flow control unit, and the gas flow of gas in a gas flow control valve entering the heat accumulating type single-burner aluminum melting furnace is controlled through a gas flow control unit.

Specifically, an initial air flow rate is set; the real-time detected hearth temperature, the smoke exhaust temperature, the combustion air temperature and the fuel gas temperature are used as input quantities of an air-fuel ratio control unit to obtain a real-time air-fuel ratio; the air-fuel ratio, the initial air flow and the air flow detected in real time are used as input quantities of an air flow control unit, and the air flow control unit is used for controlling the air flow of combustion air in a combustion air flow regulating valve into the heat accumulating type single-burner aluminum melting furnace.

the setting of the air-fuel ratio according to the combustion stage and the combustion mode of the heat accumulating type single-burner aluminum melting furnace is as follows: in a working interval which is usually set by a heat accumulating type single-burner aluminum melting furnace, the optimal air-fuel ratio is determined by taking the fastest temperature rise as a target or according to the flame characteristics of a hearth, and the optimal air-fuel ratio is taken as the set air-fuel ratio.

Or, the setting of the air-fuel ratio according to the combustion stage and the combustion mode of the heat accumulating type single-burner aluminum melting furnace means: selecting an optimal air-fuel ratio as an initial air-fuel ratio, and setting an upper temperature limit set value; and performing combustion control by using the optimal air-fuel ratio, and gradually changing the air-fuel ratio when the temperature reaches the upper temperature limit set value to finally determine the set air-fuel ratio.

Or, the setting of the air-fuel ratio according to the combustion stage and the combustion mode of the heat accumulating type single-burner aluminum melting furnace means: and in an experience database of the work of the heat accumulating type single-burner aluminum melting furnace, searching numerical values corresponding to the combustion stage and the combustion mode of the heat accumulating type single-burner aluminum melting furnace to calculate the air-fuel ratio, wherein the air-fuel ratio is used as the set air-fuel ratio.

And a furnace temperature measuring thermocouple is arranged on the side wall of the middle part of the heat accumulating type single-burner aluminum melting furnace so as to detect the hearth temperature of the heat accumulating type single-burner aluminum melting furnace in real time.

And a smoke discharge temperature thermocouple is arranged at the smoke discharge position at the top of the heat accumulating type single-burner aluminum melting furnace so as to detect the smoke discharge temperature of the heat accumulating type single-burner aluminum melting furnace in real time.

A combustion-supporting fan and an air supply pipeline are arranged, and the combustion-supporting fan is connected with the heat accumulating type single-burner aluminum melting furnace through the air supply pipeline; the combustion air flow regulating valve is arranged on the air supply pipeline; and a combustion-supporting air temperature thermocouple is also arranged on the air supply pipeline so as to detect the temperature of combustion-supporting air entering the heat accumulating type single-burner aluminum melting furnace in real time.

Arranging a fuel gas supply device and a fuel gas supply pipeline, wherein the fuel gas supply device is connected with the heat accumulating type single-burner aluminum melting furnace through the fuel gas supply pipeline; the gas flow regulating valve is arranged on the gas supply pipeline; and a thermocouple for measuring the gas temperature is also arranged on the gas supply pipeline so as to detect the temperature of the gas entering the heat accumulating type single-burner aluminum melting furnace in real time.

Compared with the prior art, the invention has the following advantages and beneficial effects: the combustion control method of the heat accumulating type single-burner aluminum melting furnace with the adjustable air-fuel ratio can realize automatic adjustment of the air-fuel ratio, so that the system can better adapt to the change of the combustion characteristics of the aluminum melting furnace in different combustion stages, and the purposes of saving energy, reducing consumption and improving the quality of aluminum melting are achieved.

Drawings

FIG. 1 is a schematic control principle diagram of a heat accumulating type single burner combustion control method with adjustable air-fuel ratio of the invention;

FIG. 2 is a schematic view of a control system implementing the control method of the present invention;

FIG. 3 is a schematic diagram of the input and output signal components of the control mechanism in the control system;

Wherein, 1 is a heat accumulating type single burner aluminum melting furnace, 2 is a combustion fan, 3 is a heat exchanger, 4 is an air supply pipeline, 5 is a gas supply pipeline, 6 is a combustion air flow regulating valve, 7 is a combustion air flow meter, 8 is a gas flow regulating valve, 9 is a gas flow meter, 10 is a programmable logic controller PLC, 11 is a thermocouple for measuring furnace temperature, 12 is a combustion air temperature thermocouple, 13 is a thermocouple for measuring gas temperature, 14 is a combustion air pressure gauge, 15 is a pressure measuring sensor before the combustion air flow regulating valve, 16 is a pressure measuring sensor after the combustion air flow regulating valve, 17 is a pressure measuring sensor before the gas flow regulating valve, 18 is a pressure measuring sensor after the gas flow regulating valve, 19 is a gas pressure gauge, 20 is a gas electromagnetic valve, 21 is a gas safety cut-off valve, 22 is a gas diffusion electromagnetic valve, 23 is a gas leakage detecting electromagnetic valve, 24 is a touch screen, and 25 is a gas pressure regulating valve.

Detailed Description

the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.