A system and method for realizing oxygen-enriched combustion of a manheim furnace by using by-product oxygen

Abstract

The present application relates to a kind of system and method for realizing manheim furnace oxygen-enriched combustion with by-product oxygen.The system for realizing manheim furnace oxygen-enriched combustion with by-product oxygen includes: oxygen supply unit, air supply unit, tail gas circulation unit, gas mixing unit, oxygen-enriched gas supply unit, control system, manheim furnace combustion unit and flue gas heat recovery unit, gas mixing unit is communicated with oxygen supply unit, air supply unit, tail gas circulation unit respectively, and by-product oxygen, combustion air, circulating flue gas are mixed to prepare oxygen-enriched combustion gas;Supply the combustion of natural gas of manheim furnace to provide oxygen-enriched combustion gas, and oxygen concentration and total flow of oxygen-enriched gas are monitored in real time and oxygen blending amount is adjusted;Flue gas heat recovery unit carries out heat exchange between oxygen-enriched combustion gas and flue gas output by manheim furnace, preheats oxygen-enriched combustion gas, and reduces the temperature of emission flue gas, realizes flue gas heat recovery;So as to reduce the heat loss of natural gas combustion, by-product oxygen is effectively utilized.

Description

Technical Field

[0001] This invention relates to the field of heating and combustion technology for Mannheim furnaces in potassium sulfate production, and more specifically, to a system and method for achieving oxygen-enriched combustion in a Mannheim furnace using byproduct oxygen. Background Technology

[0002] The Mannheim furnace is the core reaction equipment for the production of potassium sulfate in the Mannheim process. The reaction conditions need to be maintained at 520~540℃, relying on natural gas combustion in the combustion chamber for continuous heating.

[0003] Existing conventional air-assisted combustion processes suffer from core drawbacks such as high energy consumption, low thermal efficiency, and significant environmental emission pressures. Specifically, the problems include substantial ineffective heat loss and extremely low energy utilization. Conventional air contains 78% nitrogen and other inert gases, which do not participate in the combustion reaction. After being heated to 750-850℃, it is directly discharged with the flue gas, carrying away a large amount of heat. Taking the production of 1 ton of potassium sulfate as an example: natural gas combustion releases a total of 2,313,350 kilojoules of heat; the reaction absorbs only 23.56% of the total heat; the heating of raw materials and the evaporation of moisture absorb 35.94% of the heat; the heating of nitrogen in the air absorbs 17.15% of the heat; and the high-temperature flue gas carries away 38.05% of the heat, leaving only about 42% of the heat effectively utilized. A large amount of heat energy is wasted with the flue gas, resulting in high natural gas consumption costs.

[0004] Existing pure oxygen combustion technology cannot be directly adapted to Mannheim furnaces. High-purity pure oxygen combustion in the industry suffers from several fatal shortcomings: high equipment modification costs, requiring dedicated pure oxygen burners, nozzle modifications, and combustion numerical simulations, resulting in significant investment; severe furnace damage, as the flame temperature of pure oxygen combustion can reach 3000℃, 2-3 times that of conventional air-assisted combustion (1050~1500℃), and the Mannheim furnace reaction chamber is made of high-alumina bricks, which significantly shortens the furnace lining's lifespan due to the extremely high temperature; a sharp increase in safety risks, as the explosion limit of natural gas in pure oxygen is 5.4%~59.2%, and the upper explosion limit is 3.95 times that of ambient air, making it highly susceptible to combustion and explosion during flameout or backfire, compromising production safety; and high oxygen production costs, as separately equipped membrane or cryogenic oxygen production equipment increases system complexity and operating energy consumption.

[0005] Some chemical companies have installed hydrogen production via water electrolysis and nitrogen production via air separation, which continuously produce by-product oxygen. However, there is currently no mature and complete system to stably use the by-product oxygen for oxygen-enriched combustion in a Mannheim furnace. Small-scale simple oxygen addition attempts lack closed-loop concentration control, resulting in large fluctuations in oxygen content and problems such as unstable combustion, excessive NOx, and uncontrolled furnace temperature, making it impossible to achieve stable industrial operation.

[0006] In summary, the existing air-assisted combustion process for Mannheim furnaces has high energy consumption and poor thermal efficiency, while the pure oxygen combustion scheme has multiple defects in equipment, safety, and cost. There is a lack of a complete utilization system for the by-product oxygen adapted to Mannheim furnaces. There is an urgent need for a low-cost, safe, stable, and waste heat recovery oxygen-enriched combustion technology. Summary of the Invention

[0007] The technical problem to be solved by this invention is that existing Mannheim furnaces suffer from high heat loss during natural gas combustion, low energy utilization, high safety risks during pure oxygen combustion, and the inability to utilize by-product oxygen as a resource.

[0008] To solve the above-mentioned technical problems, according to one aspect of the present invention, a system for achieving oxygen-enriched combustion in a Mannheim furnace using by-product oxygen is provided, comprising: an oxygen supply unit for providing by-product oxygen after pressure reduction and stabilization; an air supply unit for supplying basic combustion air; a tail gas recirculation unit for recovering and diverting low-temperature flue gas after combustion in the Mannheim furnace for reuse; a gas mixing unit connected to the oxygen supply unit, air supply unit, and tail gas recirculation unit respectively, for mixing by-product oxygen, combustion air, and recirculated flue gas to prepare oxygen-enriched combustion gas; and an oxygen-enriched gas supply unit connected to the gas mixing unit, for providing oxygen-enriched combustion gas to the natural gas supplied to the Mannheim furnace for combustion through an oxygen-enriched gas delivery pipeline, and for real-time monitoring and adjustment of the oxygen concentration and total flow rate of the oxygen-enriched gas. Oxygen blending quantity; control system, electrically connected to the oxygen supply unit, tail gas recirculation unit, air supply unit, and oxygen-enriched supply unit respectively, receiving monitoring signals and automatically adjusting the medium ratio to stably maintain the oxygen concentration of the oxygen-enriched combustion gas at a preset value; Mannheim furnace combustion unit, receiving the oxygen-enriched combustion gas mixed with natural gas for combustion, providing a heat source for potassium sulfate synthesis; flue gas heat recovery unit, the tail gas recirculation unit is connected to the output port of the flue gas output from the Mannheim furnace combustion unit through the flue gas pipeline, the flue gas heat recovery unit is set on the flue gas pipeline and the oxygen-enriched gas delivery pipeline, used to exchange heat between the oxygen-enriched combustion gas and the flue gas output from the Mannheim furnace, preheat the oxygen-enriched combustion gas, reduce the temperature of the emitted flue gas, and realize the recovery and utilization of flue gas heat.

[0009] According to an embodiment of the present invention, the oxygen supply unit may include an electrolyzer and an oxygen flow control valve. The oxygen flow control valve is used to control the oxygen concentration of the oxygen-enriched gas mixture. By-product oxygen is produced at the anode of the electrolyzer. The source of the by-product oxygen is a water electrolysis hydrogen production device or a cryogenic air separation nitrogen production device. The initial pressure of the by-product oxygen is 0.1~2.0MPa and the purity is ≥90%. The pressure is reduced to 0.01~0.05MPa by the oxygen flow control valve and then delivered to the gas mixing unit.

[0010] According to an embodiment of the present invention, the exhaust gas recirculation unit may include a variable frequency induced draft fan and a circulating flue gas flow control valve connected in series from the output end of the flue gas heat recovery unit, and further connected to a gas mixing unit. The circulating flue gas flow control valve is used to control the content of carbon dioxide in the oxygen-enriched gas and the recovery of flue gas heat by partially circulating the flue gas. An exhaust gas emission branch is provided between the variable frequency induced draft fan and the circulating flue gas flow control valve. The exhaust gas emission branch includes an exhaust gas emission pipe and an online nitrogen oxide detector for monitoring the concentration of nitrogen oxides in the exhaust gas, and an exhaust gas emission control valve for controlling the emission amount of the flue gas, which monitors the concentration of nitrogen oxides in the exhaust gas in real time and controls the system to adjust the exhaust gas flow rate in conjunction with the exhaust gas emission control valve to ensure that the exhaust gas meets emission standards. The high-temperature flue gas discharged from the Mannheim furnace first enters the flue gas heat recovery unit to recover waste heat. After being cooled and pressurized by the variable frequency induced draft fan, the flue gas is diverted by the circulating flue gas flow control valve, with a portion sent to the gas mixing unit and the remaining flue gas entering the exhaust gas emission pipe of the exhaust gas emission branch.

[0011] According to an embodiment of the present invention, the oxygen-enriched supply unit may include an online oxygen concentration detector, an oxygen-enriched flow control valve, and an oxygen-enriched flow meter disposed on the oxygen-enriched gas delivery pipeline. The online oxygen concentration detector is disposed between the gas mixing unit and the flue gas heat recovery unit, and the oxygen-enriched flow control valve and the oxygen-enriched flow meter are disposed between the flue gas heat recovery unit and the Mannheim furnace combustion unit. The oxygen-enriched flow control valve is used to control the flow rate of the oxygen-enriched mixed gas.

[0012] According to an embodiment of the present invention, the Mannheim furnace combustion unit may include a burner, which is connected to an input natural gas and an oxygen-enriched supply unit to provide heat to the Mannheim furnace. A reaction thermometer is installed on the Mannheim furnace to measure the temperature inside the furnace. A natural gas flow control valve is installed on the natural gas input pipeline to control the amount of natural gas input, thereby controlling the reaction temperature of the Mannheim furnace.

[0013] According to an embodiment of the present invention, the air supply unit may include a variable frequency blower for supplying ambient air to the gas mixing unit; the flue gas heat recovery unit is a reheater; and the gas mixing unit is a Venturi mixer or a static mixer.

[0014] According to an embodiment of the present invention, the oxygen concentration range of the oxygen-enriched combustion-supporting gas generated by the gas mixing unit can be 23% to 30%, with an optimal target concentration of 26%.

[0015] According to an embodiment of the present invention, the online oxygen concentration detector can collect oxygen content signals in real time and transmit them to the control system. The control system adjusts the opening of the oxygen flow control valve through a PID algorithm to form a closed-loop control loop, so that the oxygen concentration of the oxygen-enriched gas is stabilized at 26%±0.5%.

[0016] According to another aspect of the present invention, a method for achieving oxygen-enriched combustion in a Mannheim furnace using by-product oxygen is provided. Based on the above-described system implementation for achieving oxygen-enriched combustion in a Mannheim furnace using by-product oxygen, the method includes the following steps: S1, supplying by-product oxygen, which is produced by an electrolytic cell, pressure reduced and stabilized by a valve, and then transported to a gas mixing unit; S2, supplying basic combustion air, which is drawn from the ambient air by a variable frequency blower, and after adjusting the flow rate, is sent to the gas mixing unit; S3, supplying circulating low-temperature flue gas, which is recovered by a flue gas heat recovery unit and pressurized by a variable frequency induced draft fan, and then diverted to the gas mixing unit; S4, ternary medium mixing, where by-product oxygen, air, and circulating flue gas are fully mixed in the mixing unit to generate... Oxygen-enriched combustion gas with an oxygen concentration of 23%~30%; S5, closed-loop automatic control, real-time online monitoring of the oxygen concentration and total flow of the oxygen-enriched gas, and the control system automatically adjusts the blending ratio of by-product oxygen through a PID algorithm to maintain the oxygen concentration stable at the preset target value; S6, oxygen-enriched combustion heating, the oxygen-enriched combustion gas is delivered to the burner, mixed with natural gas, and then burned in a Mannheim furnace to provide heating, maintaining a reaction temperature of 520~540℃ in the furnace; S7, exhaust gas environmental protection pipe control, real-time monitoring of nitrogen oxide (NOx) concentration in the exhaust gas, and automatic adjustment of the exhaust gas emission valve to ensure that pollutants meet standards; S8, flue gas waste heat recovery, the combustion flue gas first enters the flue gas heat recovery unit to recover heat, and after cooling, part of it is returned for blending and part of it is discharged in compliance with standards.

[0017] According to an embodiment of the present invention, the preset target oxygen concentration of the oxygen-enriched combustion-supporting gas can be 26%.

[0018] According to an embodiment of the present invention, in step S1, the purity of the by-product oxygen can be ≥90%, and the conveying pressure after depressurization can be controlled at 0.01~0.05MPa.

[0019] Compared with the prior art, the technical solution provided by the embodiments of the present invention can achieve at least the following beneficial effects:

[0020] The system and method for achieving oxygen-enriched combustion in a Mannheim furnace using byproduct oxygen according to the present invention can significantly reduce natural gas consumption and achieve remarkable energy savings and efficiency improvements. Increasing the oxygen content of the combustion-supporting gas from 21% in air to a stable 26% reduces the total amount of flue gas generated by approximately 20%; the system's thermal energy utilization rate increases from the original 42% to over 56%, resulting in a relative increase in thermal efficiency of 33%; the theoretical combustion temperature increases by approximately 175°C; the intensity of radiative heat transfer within the furnace is enhanced; the material heating rate is accelerated; and the potassium sulfate production capacity is simultaneously increased under the same equipment conditions.

[0021] The system and method for achieving oxygen-enriched combustion in a Mannheim furnace using by-product oxygen, according to the present invention, achieves low-cost resource utilization of by-product oxygen and reduces operating investment. It directly reuses existing by-product oxygen from the plant's water electrolysis hydrogen production and air separation units, eliminating the need for new dedicated oxygen production equipment and turning by-product gas into a valuable resource. It also eliminates the need to replace expensive dedicated pure oxygen burners and to undertake large-scale modifications to the high-alumina brick lining of the Mannheim furnace, resulting in extremely low equipment modification costs, a simple overall system structure, and low maintenance difficulty.

[0022] The system and method for achieving oxygen-enriched combustion in a Mannheim furnace according to the present invention balances high-temperature control and safe production, avoiding the risks of pure oxygen combustion. By introducing low-temperature circulating flue gas and mixing it with by-product oxygen and air, the oxygen concentration of the combustion-supporting gas is diluted, controlling the flame temperature within a range suitable for the high-alumina brick lining and preventing furnace body burn-off at ultra-high temperatures of 3000℃. Simultaneously, the oxygen concentration in the mixed gas is far lower than that of pure oxygen, significantly narrowing the natural gas explosion limit range, substantially reducing the risk of combustion and explosion during flameout and backfire, and greatly improving production safety.

[0023] The system and method for achieving oxygen-enriched combustion in a Mannheim furnace using byproduct oxygen, according to the present invention, are environmentally friendly and reduce emissions, lowering pollutant emissions. The reduction in natural gas consumption directly decreases CO2 greenhouse gas emissions; oxygen-enriched combustion combined with flue gas recirculation suppresses the formation of thermal NOx, and with the addition of an online NOx monitoring and automatic control system for tail gas, nitrogen oxide emissions are continuously reduced, meeting the ultra-low emission environmental protection requirements of the chemical industry and contributing to green and low-carbon production for enterprises.

[0024] The system and method for achieving oxygen-enriched combustion in a Mannheim furnace according to the present invention utilizes by-product oxygen, featuring fully automatic closed-loop control and stable and controllable operating conditions. Employing PID closed-loop automatic adjustment, it monitors oxygen concentration, flue gas NOx, and gas flow rate online in real time, automatically linking valves and fans for adjustment. Oxygen concentration fluctuations are controlled within ±0.5%, ensuring stable combustion conditions and avoiding problems such as furnace temperature fluctuations and incomplete combustion caused by manual adjustment delays. This system is suitable for continuous and stable production in Mannheim furnaces. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention.

[0026] Figure 1 This is a schematic diagram illustrating a system for achieving oxygen-enriched combustion in a Mannheim furnace using by-product oxygen according to an embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains. The terms “first,” “second,” and similar terms used in the specification and claims of this patent application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an” or “a” and similar terms do not indicate a limitation of quantity, but rather indicate the presence of at least one.

[0029] Figure 1 This is a schematic diagram illustrating a system for achieving oxygen-enriched combustion in a Mannheim furnace using by-product oxygen according to an embodiment of the present invention.

[0030] like Figure 1 As shown, the system for achieving oxygen-enriched combustion in the Mannheim furnace 5 using by-product oxygen includes: an oxygen supply unit, an air supply unit, a tail gas recirculation unit, a gas mixing unit, an oxygen-enriched supply unit, a control system, a Mannheim furnace combustion unit, and a flue gas heat recovery unit.

[0031] The oxygen supply unit is used to provide by-product oxygen after pressure reduction and stabilization; the air supply unit is used to supply basic combustion air; the exhaust gas recirculation unit is used to recover the low-temperature flue gas after combustion in the Mannheim furnace 5 and divert it for reuse; the gas mixing unit is connected to the oxygen supply unit, the air supply unit, and the exhaust gas recirculation unit respectively, and mixes the by-product oxygen, combustion air, and recirculated flue gas to prepare oxygen-enriched combustion gas.

[0032] The oxygen-enriched supply unit is connected to the gas mixing unit and provides combustion-supporting oxygen-enriched gas to the natural gas combustion of the Mannheim furnace 5 through the oxygen-enriched gas delivery pipeline. It monitors the oxygen concentration and total flow rate of the oxygen-enriched gas in real time and adjusts the amount of oxygen mixed.

[0033] The control system is electrically connected to the oxygen supply unit, exhaust gas recirculation unit, air supply unit, and oxygen-enriched supply unit, respectively. It receives monitoring signals and automatically adjusts the medium ratio to stably maintain the oxygen concentration of the oxygen-enriched combustion gas at a preset value.

[0034] The Mannheim furnace combustion unit receives oxygen-enriched combustion gas mixed with natural gas for combustion, providing a heat source for potassium sulfate synthesis.

[0035] The exhaust gas recirculation unit is connected to the outlet of the flue gas output from the combustion unit of the Mannheim furnace 5 through the flue gas pipeline. The flue gas heat recovery unit is set on the flue gas pipeline and the oxygen-enriched gas delivery pipeline. It is used to exchange heat between the oxygen-enriched combustion gas and the flue gas output from the Mannheim furnace 5, preheat the oxygen-enriched combustion gas, and reduce the temperature of the exhaust gas, so as to realize the recovery and utilization of flue gas heat.

[0036] According to one or more embodiments of the present invention, the oxygen supply unit includes an electrolyzer 1 and an oxygen flow control valve 21. The oxygen flow control valve 21 is used to control the oxygen concentration of the oxygen-enriched mixed gas. By-product oxygen is produced at the anode of the electrolyzer 1. The source of the by-product oxygen is an electrolytic water hydrogen production unit or a cryogenic air separation nitrogen production unit. The by-product oxygen has an initial pressure of 0.1~2.0 MPa and a purity of ≥90%. It is depressurized to 0.01~0.05 MPa by the oxygen flow control valve 21 and then delivered to the gas mixing unit.

[0037] The system and method for achieving oxygen-enriched combustion in a Mannheim furnace using by-product oxygen, according to the present invention, achieves low-cost resource utilization of by-product oxygen and reduces operating investment. It directly reuses existing by-product oxygen from the plant's water electrolysis hydrogen production and air separation units, eliminating the need for new dedicated oxygen production equipment and turning by-product gas into a valuable resource. It also eliminates the need to replace expensive dedicated pure oxygen burners and to undertake large-scale modifications to the high-alumina brick lining of the Mannheim furnace, resulting in extremely low equipment modification costs, a simple overall system structure, and low maintenance difficulty.

[0038] According to one or more embodiments of the present invention, the exhaust gas recirculation unit includes a variable frequency induced draft fan 6 and a circulating flue gas flow control valve 24 connected in series from the output end of the flue gas heat recovery unit, and further connected to a gas mixing unit. The circulating flue gas flow control valve 24 is used to control the content of carbon dioxide in the oxygen-enriched gas and the recovery of flue gas heat by partially circulating the flue gas. An exhaust gas emission branch is provided between the variable frequency induced draft fan 6 and the circulating flue gas flow control valve 24. The exhaust gas emission branch includes an exhaust gas emission pipe and an online nitrogen oxide detector 11 for monitoring the concentration of nitrogen oxides in the exhaust gas and an exhaust gas emission control valve 25 for controlling the emission amount of the flue gas, which are installed on the exhaust gas emission pipe. The nitrogen oxide concentration in the exhaust gas is monitored in real time, and the control system is linked with the exhaust gas emission control valve 25 to adjust the exhaust gas emission flow rate to ensure that the exhaust gas meets the emission standards. The high-temperature flue gas discharged from the Mannheim furnace 5 is first passed into the flue gas heat recovery unit to recover waste heat. After cooling, the flue gas is pressurized by the variable frequency induced draft fan 6 and then diverted through the circulating flue gas flow control valve 24. Part of the flue gas is sent into the gas mixing unit, and the remaining flue gas enters the exhaust gas discharge pipe of the exhaust gas discharge branch.

[0039] According to one or more embodiments of the present invention, the oxygen-enriched supply unit includes an online oxygen concentration detector 8, an oxygen-enriched flow control valve 22, and an oxygen-enriched gas flow meter 9 disposed on the oxygen-enriched gas delivery pipeline. The online oxygen concentration detector 8 is disposed between the gas mixing unit and the flue gas heat recovery unit, and the oxygen-enriched flow control valve 22 and the oxygen-enriched gas flow meter 9 are disposed between the flue gas heat recovery unit and the Mannheim furnace 5 combustion unit. The oxygen-enriched flow control valve 22 is used to control the flow rate of the oxygen-enriched mixed gas.

[0040] According to one or more embodiments of the present invention, the Mannheim furnace combustion unit includes a burner 4, which is connected to an input natural gas and an oxygen-enriched supply unit to provide heat to the Mannheim furnace 5. A reaction thermometer 10 is installed on the Mannheim furnace 5 to measure the temperature inside the Mannheim furnace 5. A natural gas flow control valve 23 is installed on the natural gas input pipeline to control the natural gas input, thereby controlling the reaction temperature of the Mannheim furnace 5.

[0041] According to one or more embodiments of the present invention, the air supply unit includes a variable frequency blower 2 for supplying ambient air to the gas mixing unit; the flue gas heat recovery unit is a reheater 3; and the gas mixing unit is a Venturi mixer 7 or a static mixer.

[0042] According to one or more embodiments of the present invention, the oxygen concentration range of the oxygen-enriched combustion-supporting gas generated by the gas mixing unit is 23% to 30%, with an optimal target concentration of 26%.

[0043] The system and method for achieving oxygen-enriched combustion in a Mannheim furnace according to the present invention balances high-temperature control and safe production, avoiding the risks of pure oxygen combustion. By introducing low-temperature circulating flue gas and mixing it with by-product oxygen and air, the oxygen concentration of the combustion-supporting gas is diluted, controlling the flame temperature within a range suitable for the high-alumina brick lining and preventing furnace body burn-off at ultra-high temperatures of 3000℃. Simultaneously, the oxygen concentration in the mixed gas is far lower than that of pure oxygen, significantly narrowing the natural gas explosion limit range, substantially reducing the risk of combustion and explosion during flameout and backfire, and greatly improving production safety.

[0044] According to one or more embodiments of the present invention, the online oxygen concentration detector 8 collects oxygen content signals in real time and transmits them to the control system. The control system adjusts the opening of the oxygen flow control valve 21 through a PID algorithm to form a closed-loop control circuit, so that the oxygen concentration of the oxygen-enriched gas is stabilized at 26%±0.5%.

[0045] The system and method for achieving oxygen-enriched combustion in a Mannheim furnace according to the present invention utilizes by-product oxygen, featuring fully automatic closed-loop control and stable and controllable operating conditions. Employing PID closed-loop automatic adjustment, it monitors oxygen concentration, flue gas NOx, and gas flow rate online in real time, automatically linking valves and fans for adjustment. Oxygen concentration fluctuations are controlled within ±0.5%, ensuring stable combustion conditions and avoiding problems such as furnace temperature fluctuations and incomplete combustion caused by manual adjustment delays. This system is suitable for continuous and stable production in Mannheim furnaces.

[0046] According to another aspect of the present invention, a method for achieving oxygen-enriched combustion in a Mannheim furnace 5 using by-product oxygen is provided. Based on the above-described system implementation for achieving oxygen-enriched combustion in a Mannheim furnace 5 using by-product oxygen, the method includes the following steps:

[0047] S1. Supply by-product oxygen. Electrolyzer 1 produces by-product oxygen, which is then pressure-reduced and stabilized by valves and transported to the gas mixing unit.

[0048] S2. Supply basic combustion air, and the variable frequency blower 2 draws in ambient air, adjusts the flow rate, and sends it into the gas mixing unit.

[0049] S3. Supply circulating low-temperature flue gas. The high-temperature flue gas from the Mannheim furnace 5 is recovered by the waste heat recovery unit and pressurized by the variable frequency induced draft fan 6 before being diverted to the gas mixing unit.

[0050] S4, ternary medium mixing, by-product oxygen, air and circulating flue gas are fully mixed in the mixing unit to generate oxygen-rich combustion-supporting gas with an oxygen concentration of 23%~30%;

[0051] S5. Closed-loop automatic control, online real-time monitoring of oxygen concentration and total flow of oxygen-enriched gas, the control system automatically adjusts the blending ratio of by-product oxygen through PID algorithm to maintain the oxygen concentration stable at the preset target value.

[0052] S6. Oxygen-enriched combustion heating: Oxygen-enriched combustion gas is delivered to burner 4, mixed with natural gas, and then burned in Mannheim furnace 5 to provide heating, maintaining a reaction temperature of 520~540℃ in the furnace.

[0053] S7. Exhaust gas environmental protection pipe control, real-time monitoring of nitrogen oxide (NOx) concentration in exhaust gas, automatic adjustment of exhaust gas emission valves to ensure that pollutants meet standards;

[0054] S8. Waste heat recovery of flue gas: The combustion flue gas first enters the flue gas heat recovery unit to recover heat. After cooling, part of it is returned and mixed, and part of it is discharged in compliance with standards.

[0055] According to one or more embodiments of the present invention, the oxygen-enriched combustion-supporting gas has a preset target oxygen concentration of 26%.

[0056] The system and method for achieving oxygen-enriched combustion in a Mannheim furnace using byproduct oxygen according to the present invention can significantly reduce natural gas consumption and achieve remarkable energy savings and efficiency improvements. Increasing the oxygen content of the combustion-supporting gas from 21% in air to a stable 26% reduces the total amount of flue gas generated by approximately 20%; the system's thermal energy utilization rate increases from the original 42% to over 56%, resulting in a relative increase in thermal efficiency of 33%; the theoretical combustion temperature increases by approximately 175°C; the intensity of radiative heat transfer within the furnace is enhanced; the material heating rate is accelerated; and the potassium sulfate production capacity is simultaneously increased under the same equipment conditions.

[0057] According to one or more embodiments of the present invention, in step S1, the purity of the by-product oxygen is ≥90%, and the conveying pressure after depressurization is controlled to be 0.01~0.05MPa.

[0058] The system and method for achieving oxygen-enriched combustion in a Mannheim furnace using byproduct oxygen, according to the present invention, are environmentally friendly and reduce emissions, lowering pollutant emissions. The reduction in natural gas consumption directly decreases CO2 greenhouse gas emissions; oxygen-enriched combustion combined with flue gas recirculation suppresses the formation of thermal NOx, and with the addition of an online NOx monitoring and automatic control system for tail gas, nitrogen oxide emissions are continuously reduced, meeting the ultra-low emission environmental protection requirements of the chemical industry and contributing to green and low-carbon production for enterprises.

[0059] The above description is merely an exemplary embodiment of the present invention and is not intended to limit the scope of protection of the present invention, which is determined by the appended claims.

Claims

1. A system for achieving oxygen-enriched combustion in a Mannheim furnace using byproduct oxygen, wherein, include: An oxygen supply unit is used to provide by-product oxygen after pressure reduction and stabilization. Air supply unit, used to supply basic combustion air; The exhaust gas recirculation unit is used to recover the low-temperature flue gas after combustion in the Mannheim furnace and divert it for reuse; The gas mixing unit is connected to the oxygen supply unit, the air supply unit, and the exhaust gas recirculation unit respectively, and mixes the by-product oxygen, combustion air, and recirculated flue gas to prepare oxygen-rich combustion gas. An oxygen-enriched supply unit is connected to the gas mixing unit. It provides combustion-supporting oxygen-enriched mixed gas to the natural gas combustion of the Mannheim furnace through an oxygen-enriched gas delivery pipeline. It monitors the oxygen concentration and total flow rate of the oxygen-enriched gas in real time and adjusts the amount of oxygen mixed. The control system is electrically connected to the oxygen supply unit, the exhaust gas recirculation unit, the air supply unit, and the oxygen-enriched supply unit, respectively. It receives monitoring signals and automatically adjusts the medium ratio to stably maintain the oxygen concentration of the oxygen-enriched combustion gas at a preset value. The Mannheim furnace combustion unit receives a mixture of oxygen-rich combustion-supporting gas and natural gas for combustion, providing a heat source for potassium sulfate synthesis. The flue gas heat recovery unit is connected to the outlet of the flue gas output from the Mannheim furnace combustion unit via a flue gas pipeline. The flue gas heat recovery unit is installed on the flue gas pipeline and the oxygen-enriched gas delivery pipeline. It is used to exchange heat between the oxygen-enriched combustion gas and the flue gas output from the Mannheim furnace, preheat the oxygen-enriched combustion gas, and reduce the temperature of the emitted flue gas, thereby realizing the recovery and utilization of flue gas heat.

2. The system for achieving oxygen-enriched combustion in a Mannheim furnace using byproduct oxygen as described in claim 1, wherein, The oxygen supply unit includes an electrolyzer and an oxygen flow control valve. The oxygen flow control valve is used to control the oxygen concentration of the oxygen-enriched mixture. The anode of the electrolyzer produces by-product oxygen, which comes from a water electrolysis hydrogen production device or a cryogenic air separation nitrogen production device.

3. The system for achieving oxygen-enriched combustion in a Mannheim furnace using byproduct oxygen as described in claim 1, wherein, The exhaust gas recirculation unit includes a variable frequency induced draft fan and a circulating flue gas flow control valve connected in series from the output end of the flue gas heat recovery unit, and then connected to a gas mixing unit. The circulating flue gas flow control valve is used to control the content of carbon dioxide in the oxygen-enriched gas and the recovery of flue gas heat in the flue gas. An exhaust gas emission branch is set between the variable frequency induced draft fan and the circulating flue gas flow control valve. The exhaust gas emission branch includes an exhaust gas emission pipe and an online nitrogen oxide detector for monitoring the concentration of nitrogen oxides in the exhaust gas, and an exhaust gas emission control valve for controlling the emission amount of the flue gas. The system monitors the concentration of nitrogen oxides in the exhaust gas in real time and controls the exhaust gas emission control valve to adjust the exhaust gas flow rate to ensure that the exhaust gas meets emission standards. The high-temperature flue gas discharged from the Mannheim furnace is first fed into the flue gas heat recovery unit to recover waste heat. The cooled flue gas is then pressurized by the variable frequency induced draft fan and diverted through the circulating flue gas flow control valve. Part of the flue gas is sent into the gas mixing unit, and the remaining flue gas enters the exhaust gas discharge pipe of the exhaust gas discharge branch.

4. The system for achieving oxygen-enriched combustion in a Mannheim furnace using by-product oxygen as described in claim 1, wherein, The oxygen-enriched supply unit includes an online oxygen concentration detector, an oxygen-enriched flow control valve, and an oxygen-enriched flow meter installed on the oxygen-enriched gas delivery pipeline. The online oxygen concentration detector is installed between the gas mixing unit and the flue gas heat recovery unit, and the oxygen-enriched flow control valve and the oxygen-enriched flow meter are installed between the flue gas heat recovery unit and the Mannheim furnace combustion unit. The oxygen-enriched flow control valve is used to control the flow rate of the oxygen-enriched mixed gas.

5. The system for achieving oxygen-enriched combustion in a Mannheim furnace using byproduct oxygen as described in claim 1, wherein, The Mannheim furnace combustion unit includes a burner connected to an input natural gas and an oxygen-enriched supply unit to provide heat to the Mannheim furnace. A reaction thermometer is installed on the Mannheim furnace to measure the temperature inside the furnace. A natural gas flow control valve is installed on the natural gas input pipeline to control the amount of natural gas input, thereby controlling the reaction temperature of the Mannheim furnace.

6. The system for achieving oxygen-enriched combustion in a Mannheim furnace using byproduct oxygen as described in claim 1, wherein, The air supply unit includes a variable frequency fan for supplying ambient air to the gas mixing unit; the flue gas heat recovery unit is a reheater; and the gas mixing unit is a Venturi mixer or a static mixer.

7. The system for achieving oxygen-enriched combustion in a Mannheim furnace using byproduct oxygen as described in claim 1, wherein, The oxygen concentration range of the oxygen-enriched combustion-supporting gas generated by the gas mixing unit is 23%~30%, with an optimal target concentration of 26%.

8. The system for achieving oxygen-enriched combustion in a Mannheim furnace using by-product oxygen as described in claim 1, wherein, The online oxygen concentration detector collects oxygen content signals in real time and transmits them to the control system. The control system adjusts the opening of the oxygen flow control valve through a PID algorithm to form a closed-loop control circuit, so that the oxygen concentration of the oxygen-enriched gas is stabilized at 26%±0.5%.

9. A method for achieving oxygen-enriched combustion in a Mannheim furnace using by-product oxygen, wherein the method is implemented based on the system described in any one of claims 1-8, and the method comprises the following steps: S1. Supply by-product oxygen. The by-product oxygen produced by the electrolytic cell is reduced and stabilized by valves and then transported to the gas mixing unit. S2. Supply basic combustion air, and the variable frequency blower draws in ambient air, adjusts the flow rate, and sends it into the gas mixing unit. S3. Supply circulating low-temperature flue gas. The high-temperature flue gas from the Mannheim furnace is fed into the gas mixing unit after waste heat recovery by the flue gas heat recovery unit and pressurization by the variable frequency induced draft fan. S4, ternary medium mixing, by-product oxygen, air and circulating flue gas are fully mixed in the mixing unit to generate oxygen-rich combustion-supporting gas with an oxygen concentration of 23%~30%; S5. Closed-loop automatic control, online real-time monitoring of oxygen concentration and total flow of oxygen-enriched gas, the control system automatically adjusts the blending ratio of by-product oxygen through PID algorithm to maintain the oxygen concentration stable at the preset target value. S6. Oxygen-enriched combustion heating: Oxygen-enriched combustion gas is delivered to the burner, mixed with natural gas, and then burned in the Mannheim furnace to provide heating, maintaining a reaction temperature of 520~540℃ in the furnace. S7. Exhaust gas environmental protection pipe control, real-time monitoring of nitrogen oxide (NOx) concentration in exhaust gas, automatic adjustment of exhaust gas emission valves to ensure that pollutants meet standards; S8. Waste heat recovery of flue gas: The combustion flue gas first enters the flue gas heat recovery unit to recover heat. After cooling, part of it is returned and mixed, and part of it is discharged in compliance with standards.

10. The system method for achieving oxygen-enriched combustion in a Mannheim furnace using by-product oxygen as described in claim 9, wherein, The target oxygen concentration of the oxygen-enriched combustion-supporting gas is 26%.

Images