A control method for a diffusion combustion system of an aluminum melting furnace

Abstract

The present application relates to non-ferrous metal combustion technical field, specifically to a kind of dispersion type combustion system control method of aluminium melting furnace, comprising the following steps: adjusting the installation position of burner;Adjust the initial position of natural gas nozzle front valve opening;Multiple adjustment aluminium melting furnace burner ignition gun flame shape and length;Control the switching of flame mode and the proportion of primary air and secondary air;Precise control air-fuel ratio and residual oxygen content of furnace gas;Adjust the continuous blowout purging time of main fire gun and the time of not detecting flame after natural gas nozzle front valve opening, control the action of nozzle front valve;Adjust the frequency of dust removal system fan;Before ignition, if auxiliary smoke gate is in closed state, 3s is needed to open main fire gun again;And increase wild air valve in exhaust fan pipeline;Set ton gas consumption and burner interlock function: set ton gas consumption target value, when actual ton gas consumption reaches target value, burner is extinguished and reminds operator that melting is completed. The method helps to reduce product gas consumption of circular economy smelting furnace, reduce metal burning loss.

Description

Technical Field

[0001] The present invention relates to the technical field of nonferrous metal combustion, and in particular to a control method for a diffusion combustion system of an aluminum melting furnace. Background Art

[0002] Traditional premixed regenerative combustion systems emit high levels of nitrogen oxides. Against the backdrop of the dual-carbon strategy and increasingly stringent environmental protection requirements, upgrading aluminum furnace combustion systems to achieve energy conservation and low-nitrogen emissions is both necessary and urgent. Technical upgrades to aluminum furnace combustion systems are crucial for both energy conservation and reduced atmospheric pollutant emissions. Summary of the Invention

[0003] The object of the present invention is to provide a control method for a diffuse combustion system of an aluminum melting furnace, which helps to reduce the product gas consumption of a circular economy melting furnace and reduce metal burnout.

[0004] The technical solution of the present invention is: a control method for a diffusion combustion system of an aluminum melting furnace, using a diffusion burner with two flame modes: rigid flame and flexible bright flame, comprising the following steps:

[0005] (1) Adjust the installation position of the burner so that the main gun and the ignition gun of the burner form an angle of 15°, and configure the cooling air pipe for the ignition gun of the burner;

[0006] (2) Adjust the initial opening position of the natural gas nozzle front valve to 20% to ensure the combustion and melting rate;

[0007] (3) Adjust the flame shape and length of the burner ignition gun of the aluminum melting furnace several times;

[0008] (4) Control the switching of flame modes and the ratio of primary air to secondary air;

[0009] (5) Accurately control the air-fuel ratio and residual oxygen content in the furnace gas: by using a flue gas analyzer to measure the flue gas composition multiple times, measure the flue gas oxygen content and carbon monoxide content, and determine the optimal air-fuel ratio coefficient;

[0010] (6) Adjust the continuous flameout purge time of the main gun and the time when no flame is detected after the natural gas nozzle front valve is opened, and control the action of the nozzle front valve;

[0011] (7) Adjust the fan frequency of the dust removal system; optimize the control of the auxiliary smoke damper. Before ignition, if the auxiliary smoke damper is in the closed state, it needs to be opened for 3 seconds before the main ignition gun is opened; and add a wild wind valve to the exhaust fan pipeline;

[0012] (8) Set the interlocking function of gas consumption per ton and burner: set the target value of gas consumption per ton. When the actual gas consumption per ton reaches the target value, the burner stops firing and reminds the operator that the melting is completed.

[0013] Furthermore, in step (4), during the initial startup flow stage, the primary air flow is set to 1 / 4 of the rated load, the primary air ratio is 20%, and the secondary air ratio is 80%.

[0014] Furthermore, when the furnace temperature rises above 750°C, the air and gas flow rates are increased to the rated load; when the furnace temperature reaches above 950°C, the primary air accounts for 5% of the rated air flow rate, and the secondary air accounts for 95% of the rated air flow rate.

[0015] Furthermore, in step (5), when the air-fuel ratio is set to 11:1, the residual oxygen content in the flue gas is detected from the auxiliary flue sampling port using a flue gas analyzer with a standard of 1.5% to 3%. The mass flow control method is adopted to independently control the gas and air flow rates to achieve a complete combustion flame with a minimum air excess coefficient, and the residual oxygen content in the furnace gas is controlled at a level of 2 to 3%.

[0016] Furthermore, in step (6), when the furnace temperature is below 750°C and the main ignition gun is extinguished for more than two consecutive times, the purge is automatically started to replace the unburned furnace exhaust gas in the furnace. The purge time is extended from 180 seconds of normal furnace startup to 360 seconds; the time when no flame is detected after the natural gas nozzle front valve is opened is shortened from the original 5 seconds to 3 seconds.

[0017] Furthermore, in step (7), the dust removal system is automatically controlled by detecting the negative pressure, and the frequency of the dust removal fan is adjusted in the range of 20-45HZ to ensure that the negative pressure of the flue of the aluminum melting furnace is around -100Pa, thereby ensuring the stability of the furnace pressure.

[0018] Furthermore, the host computer's function display, data recording, curve recording and PDA acquisition functions are added.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. Through precise control of the air-fuel ratio and residual oxygen content in the furnace gas, as well as burner installation position and angle control, metal burnout is reduced, melting efficiency is improved, natural gas consumption is optimized, and investment costs are reduced. While operating safely and reliably, melting efficiency is improved and energy consumption is reduced.

[0021] 2. By optimizing and adjusting the aluminum melting furnace's combustion system, the fuel (usually mixed with a very small amount of combustion air to maintain flame stability) and combustion air are injected separately into the furnace using a jet method where the combustion air velocity is higher than the fuel velocity. The rapid combustion air flow entrains the fuel and combustion products in the furnace, diluting the oxygen concentration in the reaction zone to achieve a low-oxygen atmosphere with a concentration of 3-15% by volume. Heat energy is released through delayed combustion with the oxygen-depleted gas, eliminating the localized high-temperature, high-oxygen zones found in traditional combustion processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a structural diagram of the furnace burner arrangement of the present invention;

[0023] In the figure: 1-furnace wall 2-furnace chamber 3-main ignition gun 4-ignition gun 5-ignition flame 6-main fire flame 7-ignition flame probe 8-main fire flame probe 9-angle 10-main ignition gun channel 11-flame probe channel 12-flame recirculation area 13-diversion port. DETAILED DESCRIPTION

[0024] To make the above features and advantages of the present invention more clearly understood, embodiments are given below with reference to the accompanying drawings for detailed description, but the present invention is not limited thereto.

[0025] refer to Figure 1

[0026] A control method for a diffusion combustion system of an aluminum melting furnace, using a diffusion burner with two flame modes: rigid flame and flexible bright flame, comprises the following steps:

[0027] The burner mainly includes a main ignition gun channel 10 which is obliquely arranged on the furnace wall 1 and extends into the furnace 2. A main ignition gun 3 is arranged at the end of the main ignition gun channel. An ignition gun 4 is arranged on the furnace wall and is connected to the main ignition gun channel and the connecting part is located in front of the main ignition gun output end. An ignition flame probe 7 is arranged in the ignition gun. A flame probe channel 11 is obliquely arranged on the upper part of the furnace wall and is connected to the main ignition gun channel and the connecting part is located in front of the main ignition gun output end. A high fire flame probe 8 is arranged in the flame probe channel.

[0028] (1) Adjust the installation position of the burner so that the main ignition gun and the ignition gun of the burner form an angle of 15°9, the ignition gun is set horizontally, the distance between the inner wall of the steel structure of the burner and the guide port 13 is 350mm, and the depth of the ignition gun inserted into the main ignition gun channel is 173mm (i.e. the ignition gun is buried). This effectively avoids the high-temperature combustion products (POC) in the flame area from directly contacting the aluminum liquid before the flame is completely burned, and can effectively reduce the oxidation and burning caused by the direct contact between some incompletely burned fuel and the high-temperature and high-oxygen area and the aluminum liquid. Optimize the installation position of the fire detection rod (because the diffuse flame does not burn in a straight line, the fire detection rod is installed on the side of the burner flame angle direction) to better detect the flame and optimize the sensitivity of the fire detection. And configure the burner ignition gun with a cooling air pipe: reduce burner flameout and extend the burner life.

[0029] (2) Optimize and adjust the initial opening position of the front valve of the natural gas nozzle to 20% to ensure the combustion and melting rate; optimize the power of the low fire position, improve the control program, safety chain, etc.

[0030] (3) Adjust the flame shape and length of the ignition gun of the aluminum melting furnace burner several times: the flame length of the ignition gun is adjusted from 150-200 mm to about 300 mm, and the success rate of the main fire of the burner is 100%.

[0031] (4) Control the switching of the flame mode and the ratio of primary air and secondary air: during the initial start-up flow stage, the flow of the primary air is set to 1 / 4 of the rated load, the primary air ratio is 20%, and the secondary air ratio is 80%.

[0032] (5) Precise control of air-fuel ratio and residual oxygen content in furnace gas: by using a flue gas analyzer to measure the flue gas composition several times, the oxygen content and carbon monoxide content in the flue gas are measured, and when the furnace temperature is below 750℃ and the carbon monoxide is low (less than 10 mg / m³), the oxygen content is appropriate at 1%-3%, and the air-fuel ratio is determined by analyzing the flue gas.

[0033] (6) Adjust the continuous blowout and purge time of the main fire gun and the time after the natural gas nozzle valve is opened without detecting the flame: when the furnace temperature is below 750℃ and the main fire gun is continuously blown out more than twice, automatic blowing is started to replace the unburned furnace waste gas in the furnace, and the blowing time is extended from 180 seconds to 360 seconds. The time after the natural gas nozzle valve is opened without detecting the flame is shortened from 5 seconds to 3 seconds. The switching time of the burner is optimized to ensure the temperature of the regenerator.

[0034] (7) Adjust the frequency of the dust removal system fan: the dust removal system is automatically controlled by detecting negative pressure, and the frequency of the dust removal fan is adjusted in the range of 20-45 HZ to ensure that the flue gas negative pressure of the aluminum melting furnace is about -100 pa, which ensures the stability of the furnace pressure and avoids the loss of furnace heat caused by excessive dust removal suction. The control of the auxiliary smoke damper is also optimized, and if the auxiliary smoke damper is closed before ignition, the main fire gun needs to be opened for 3 seconds. A wild valve is added to the exhaust fan pipeline to increase the exhaust temperature in an adjustable manner.

[0035] (8) Set the ton gas consumption and burner interlocking function: set the ton gas consumption target value, and when the actual ton gas consumption reaches the target value, the burner stops burning and reminds the operator that the melting is complete, avoiding the problem of aluminum liquid over-temperature or insufficient aluminum liquid temperature that requires multiple temperature compensation, and achieving the purpose of reducing energy consumption.

[0036] (9) Optimize the functions of the upper computer: increase the function display, data recording, curve recording and PDA acquisition functions of the upper computer, so as to facilitate the analysis and optimization of the combustion control system and the control of the furnace.

[0037] In this embodiment, when the furnace temperature rises to above 750°C, the air and gas flow rates are increased to the rated load; when the furnace temperature reaches above 950°C, the proportion of primary air to the rated air flow rate is 5%, and the proportion of secondary air to the rated air flow rate is 95%.

[0038] In this embodiment, in step (4), different flame modes are switched for different furnace gas temperatures, so that the primary air volume is changed from being uncontrolled by temperature to being controlled by temperature, ensuring that the rigid flame when heating below 850°C can greatly improve the convective heat transfer efficiency in the furnace; and the bright flame when entering the heating stage above 850°C can greatly reduce the thermal scouring of the high-temperature aluminum liquid surface, shortening the exposure time of the aluminum liquid to the residual oxygen in the furnace gas, thereby reducing oxidation burning.

[0039] In this embodiment, in step (5), when the air-fuel ratio is set to 11:1, the residual oxygen content in the flue gas is detected from the auxiliary flue sampling port using a flue gas analyzer with a standard of 1.5% to 3%. The mass flow control method is adopted to independently control the gas and air flow rates to achieve a complete combustion flame with a minimum air excess coefficient. The residual oxygen content in the furnace gas is controlled at a level of 2 to 3%. The low oxygen level can effectively reduce the oxidation and burning of the aluminum liquid.

[0040] In this embodiment, reports can be generated on the HMI screen to calculate the combustion time, natural gas consumption, and gas consumption per ton of each furnace, facilitating melting rate analysis. Alumina balls can also be replaced promptly based on abnormal changes in regenerative burner combustion parameters, such as combustion air flow, exhaust temperature, and furnace pressure, to maximize furnace heat recovery and reduce natural gas consumption per ton.

[0041] In this embodiment, by optimizing the combustion control program and parameters such as combustion-supporting air, natural gas flow, and exhaust fan frequency, the maximum combustion power of the burner and the melting speed are increased during the heating stage, the melting rate is increased to avoid the standby time of the casting machine, and the melting time is ensured to match the casting production rhythm time, thereby improving production efficiency.

[0042] This method can shorten the furnace combustion time from 6 hours to 4.5 hours, increase the melting rate by 25%, reduce the natural gas consumption per ton to 10%, and reduce the burn loss by 0.3%.

[0043] The above description is only a preferred embodiment of the present invention. For ordinary technicians in this field, according to the teachings of the present invention, it does not require creative work to design a control method for a diffusion combustion system of an aluminum melting furnace in different forms. Without departing from the principles and spirit of the present invention, all equal changes, modifications, substitutions and variations made within the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A control method for a diffusion combustion system of an aluminum melting furnace, using a diffusion burner with two flame modes: rigid flame and flexible bright flame, characterized in that: The following steps are involved: (1) Adjust the installation position of the burner so that the main gun and the ignition gun of the burner form an angle of 15°, and configure the cooling air pipe for the ignition gun of the burner; (2) Adjust the initial opening position of the natural gas nozzle front valve to 20% to ensure the combustion and melting rate; (3) Adjust the flame shape and length of the burner ignition gun of the aluminum melting furnace several times; (4) Control the switching of flame modes and the ratio of primary air to secondary air; (5) Accurately control the air-fuel ratio and residual oxygen content in the furnace gas: by using a flue gas analyzer to measure the flue gas composition multiple times, measure the flue gas oxygen content and carbon monoxide content, and determine the optimal air-fuel ratio coefficient; (6) Adjust the purge time of the main ignition gun after continuous flameout and the time when no flame is detected after the natural gas nozzle front valve is opened, and control the action of the nozzle front valve; when the furnace temperature is below 750℃ and the main ignition gun is continuously extinguished for more than two times, the purge is automatically started to replace the unburned furnace exhaust gas in the furnace, and the purge time is extended from 180 seconds at normal furnace start-up to 360 seconds; the time when no flame is detected after the natural gas nozzle front valve is opened is shortened from 5 seconds to 3 seconds; (7) Adjust the fan frequency of the dust removal system; optimize the control of the auxiliary smoke damper. Before ignition, if the auxiliary smoke damper is in the closed state, it needs to be opened for 3 seconds before the main ignition gun is opened; and add a wild wind valve to the exhaust fan pipeline; (8) Set the interlocking function of gas consumption per ton and burner: set the target value of gas consumption per ton. When the actual gas consumption per ton reaches the target value, the burner stops firing and reminds the operator that the melting is completed.

2. The control method of a diffusion combustion system of an aluminum melting furnace according to claim 1, characterized in that: In step (4), at the initial startup flow stage, the primary air flow is set to 1 / 4 of the rated load, the primary air ratio is 20%, and the secondary air ratio is 80%.

3. The control method of the diffusion combustion system of an aluminum melting furnace according to claim 2, characterized in that: When the furnace temperature rises above 750℃, the air and gas flow rates are increased to the rated load; when the furnace temperature reaches above 950℃, the primary air accounts for 5% of the rated air flow rate, and the secondary air accounts for 95% of the rated air flow rate.

4. The control method of a diffusion combustion system of an aluminum melting furnace according to claim 1, 2 or 3, characterized in that: In step (5), when the air-fuel ratio is set to 11:1, the residual oxygen content in the flue gas is detected from the auxiliary flue sampling port using a flue gas analyzer with a standard of 1.5% to 3%. The mass flow control method is used to control the gas and air flow rates separately to achieve a complete combustion flame with a minimum air excess coefficient, and the residual oxygen content in the furnace gas is controlled at a level of 2 to 3%.

5. The control method of a diffusion combustion system of an aluminum melting furnace according to claim 1, characterized in that: In step (7), the dust removal system is automatically controlled by detecting the negative pressure, and the frequency of the dust removal fan is adjusted in the range of 20-45HZ to ensure that the negative pressure of the flue of the aluminum melting furnace is around -100Pa, thereby ensuring the stability of the furnace pressure.

6. The control method of a diffusion combustion system of an aluminum melting furnace according to claim 1, characterized in that: Add the function display, data recording, curve recording and PDA acquisition functions of the host computer.

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