Energy-saving and environment-friendly combustion system and industrial furnace thereof

Abstract

The application discloses an energy-saving and environment-friendly combustion system and an industrial furnace thereof. The energy-saving and environment-friendly combustion system is provided with a gas composition detection device on an exhaust pipe. The gas composition detection device comprises a detection unit, an execution device, a protection box and a sampling port. The detection unit comprises a gas sampling probe, a sampling gas pump and a composition analysis module. The gas sampling probe is communicated with the composition analysis module through the sampling gas pump. The execution device comprises a telescopic machine and a telescopic rod. The gas sampling probe is provided with an air inlet and is fixed on the telescopic rod. The detection unit and the telescopic rod are located in the protection box. The protection box is communicated with the valve and the sampling port. The sampling port is communicated with the exhaust pipe. The service life of the gas composition detection device is greatly prolonged, the use cost is reduced, and the industrial furnace and the combustion system thereof are prevented from gradually changing to an energy-inefficient and environment-unfriendly operation state.

Description

Technical Field

[0001] This invention relates to the field of environmental protection and energy conservation technology, specifically to an energy-saving and environmentally friendly combustion system and its industrial furnace. Background Technology

[0002] Industrial furnaces are major sources of energy consumption and environmental pollutant emissions in industrial production. my country's industrial production scale is enormous; for example, its aluminum alloy and steel production each exceed half of the world's total. Therefore, it faces significant challenges in both energy consumption and environmental protection.

[0003] As is well known, on the one hand, when the supply of combustion air is insufficient, the fuel cannot burn completely, and the system energy consumption will increase sharply; on the other hand, if the air supply is excessive, the flue gas emissions will increase, and the heat lost through the flue gas will also increase, further increasing energy consumption. Both situations will increase energy consumption, which contradicts the goal of energy conservation. To ensure energy-efficient operation, the combustion system needs to automatically control the blower's airflow based on the O2 content in the exhaust gas. Controlling the O2 content in the exhaust gas to ensure a reasonable air-fuel ratio is a fundamental and essential measure.

[0004] Currently, with the widespread use of clean fuels, the main air pollutants emitted by combustion systems and industrial furnaces are CO and NOx (primarily including NO and NO2). Similarly, if an environmentally friendly combustion system and its industrial furnace operate in an environmentally unfriendly manner, it ceases to be an environmentally friendly system or furnace. To maintain the environmentally friendly operation of industrial furnaces, controlling the CO emission concentration in the exhaust gas during the low-temperature phase and controlling the NOx (including NO and NO2) emission concentration during the high-temperature phase are essential measures.

[0005] Installing O2, CO, and NOx concentration detectors on exhaust ducts and adjusting system operating parameters based on the data from these instruments is a common practice. However, most existing gas composition detection systems use electrochemical methods, which have the following drawbacks: 1. Increased detection accuracy with prolonged use (fatigue); 2. Harsh working environments in industrial production significantly shorten the lifespan of the gas concentration detection system.

[0006] Therefore, existing flue gas concentration detection systems, even with high costs, cannot operate stably for extended periods. These existing technologies can only be used experimentally for short periods in actual production and cannot be widely adopted in industry. This situation has caused combustion systems and industrial furnaces to gradually deviate from energy-saving and environmentally friendly operating principles, essentially becoming combustion systems and industrial furnaces that are neither energy-efficient nor environmentally friendly. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the present invention aims to provide an energy-saving and environmentally friendly combustion system and its industrial furnace.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] An energy-saving and environmentally friendly combustion system includes a furnace, several heat storage boxes, burners, an inlet pipe, an exhaust pipe, a blower, an induced draft fan, an airflow reversing system, a flue gas recirculation pipe, and a control system. The furnace has several air inlets, the number of which corresponds to the number of heat storage boxes, and each air inlet is connected to one heat storage box. A blower is installed on the inlet pipe, and an induced draft fan is installed on the exhaust pipe. The airflow reversing system has several switching ports, which are respectively connected to the inlet pipe, the exhaust pipe, and each heat storage box. A gas composition detection device is installed on the exhaust pipe.

[0010] The gas composition detection device includes a detection unit, an actuator, a protective box, and a sampling port. The detection unit includes a gas sampling probe, a sampling gas pump, and a composition analysis module. The gas sampling probe is connected to the composition analysis module through the sampling gas pump. The actuator includes a telescopic mechanism and a telescopic rod. The gas sampling probe has an air inlet and is fixed to the telescopic rod. Both the gas sampling probe and the telescopic rod are located inside the protective box. The protective box is connected to the sampling port, and the sampling port is connected to the exhaust pipe.

[0011] Furthermore, the airflow reversing system includes a four-way valve.

[0012] Furthermore, the energy-saving and environmentally friendly combustion system also includes a flue gas return pipe, one end of which is connected to the exhaust pipe and the other end is connected to the intake pipe, and a flue gas return valve is provided on the flue gas return pipe.

[0013] Furthermore, a return fan is also installed on the flue gas return pipe.

[0014] The present invention also provides an industrial furnace having the above-mentioned energy-saving and environmentally friendly combustion system.

[0015] The beneficial effects of this invention are as follows: The gas composition detection device is located outside the furnace. When not in use, the gas sampling probe remains outside the furnace and within a protective box, allowing the gas composition detection device to operate intermittently to detect the components in the exhaust gas. Outside of operating hours, it is in a recovery or shutdown state, which greatly extends the service life of the gas composition detection device and reduces operating costs. Furthermore, the gas sampling probe is isolated from dust and corrosive gases within the protective box, preventing these gases from entering the detection unit through the probe. This helps the gas composition detection device maintain good operating conditions for extended periods, extending its service life. The combustion system and its industrial furnace can automatically adjust the system's operating parameters in a timely manner based on the exhaust gas composition detected by the gas composition detection device, preventing the combustion system and industrial furnace from gradually becoming neither energy-efficient nor environmentally friendly. Attached Figure Description

[0016] Figure 1 This is a top view of the aluminum melting furnace in Embodiment 1 of the present invention;

[0017] Figure 2 This is a three-dimensional schematic diagram of the aluminum melting furnace in Embodiment 1 of the present invention;

[0018] Figure 3 This is a schematic diagram of the gas composition detection device involved in Embodiments 1 and 2 of the present invention;

[0019] Figure 4 This is a top view of the ladle baking device in Embodiment 2 of the present invention;

[0020] Figure 5 This is a three-dimensional schematic diagram of the ladle baking device in Embodiment 2 of the present invention. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings. It should be noted that this embodiment is based on the present technical solution and provides detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to this embodiment.

[0022] Example 1

[0023] This embodiment uses a 35-ton circular aluminum melting furnace with a diameter of 5.5 meters. Figure 1-2 As shown, the system comprises a furnace 1, tuyer 1 2, tuyer 2 11, regenerator 1 4, regenerator 2 10, burner 3, inlet pipe 8, exhaust pipe 12, blower 9, induced draft fan 6, airflow reversing system 5, flue gas return pipe 7, and a control system. The furnace 1 is connected to regenerator 1 4 via tuyer 1 2 and to regenerator 2 10 via tuyer 2 11. A blower 9 is installed on the inlet pipe 8, and an induced draft fan 6 is installed on the exhaust pipe 12. One end of the flue gas return pipe 7 is connected to... The intake pipe 8 is connected to the exhaust pipe 12 at one end; the flue gas return pipe 7 is equipped with a flue gas return valve 71, which is used to introduce the return flue gas 15 from the exhaust pipe 12 into the intake pipe 8; the airflow reversing system 5 includes a four-way valve 51 that is connected to the intake pipe 8, the exhaust pipe 12, and two heat storage boxes 4 and 10 respectively; the flue gas return pipe 7 introduces the return flue gas 15 from the exhaust pipe 12 into the intake pipe 8; the exhaust pipe 12 is connected to a gas composition detection device 13.

[0024] The above structure is the existing structure of the energy-saving and environmentally friendly combustion system. During operation, heat storage boxes 1-4 and 2-10 contain heat storage balls for storing and releasing heat. The airflow reversing system 5 connects heat storage box 1-4 to the air inlet pipe 8 and heat storage box 2-10 to the exhaust pipe 12, with the two paths being disconnected. When the blower 9 starts, when room temperature air passes through heat storage box 1-4, the heat from the heat storage balls in heat storage box 1-4 is transferred to the air, raising the air temperature to 600-1100℃ or higher. The air then enters the furnace 1 through tuyeres 1-2 to aid combustion. The combustion products (flue gas) enter heat storage box 2-10 through tuyeres 2-11, transferring the heat from the high-temperature flue gas to the heat storage balls in heat storage box 2-10, where the heat storage balls store the heat. After a certain period of time, the airflow reversing system 5 switches the airflow direction, connecting heat storage box 1-4 to the exhaust pipe 12 and heat storage box 2-10 to the air inlet pipe 8, with the two paths being disconnected. At this time, ambient air passes through heat storage box 2 10, where the heat stored in the heat storage balls is transferred to the air, raising it to a high temperature of 600-1100℃ or higher. The air then enters the furnace 1 through tuyeres 2 11 to aid combustion. Combustion products (flue gas) pass through tuyeres 1 2 into heat storage box 4, where the heat from the high-temperature flue gas is transferred to the heat storage balls, which store the heat. The reversing system 5 switches back and forth regularly between these two operating states, with tuyeres 1 2 and tuyeres 2 11 alternating between entering hot air and exiting hot flue gas. The heat release and absorption of the heat storage balls also change accordingly. The temperature of the combustion air entering the furnace 1 is always maintained at a high temperature approximately 80-150℃ lower than the exhaust flue gas temperature—for example, if the exhaust flue gas temperature is 1000℃, the combustion gas temperature will not be lower than 850℃, thus reducing fuel consumption.

[0025] To further reduce NOx emission concentration, the aforementioned energy-saving and environmentally friendly combustion system also guides a portion of the exhaust gas 14 from the exhaust pipe 12 back to the intake pipe 8 via the flue gas recirculation pipe 7. This recirculation mixes the flue gas with the combustion air, reducing the oxygen concentration in the combustion chamber and thus lowering the flame temperature and NOx emissions. The power for the flue gas recirculation comes from the pressure supplied to the flue gas 14 by the induced draft fan on the exhaust pipe 12, or from the negative pressure generated by the blower 9 on the intake pipe 8. The flue gas recirculation valve 71 controls the flow rate of the recirculated flue gas 15.

[0026] The aluminum melting furnace in this embodiment is used to melt solid aluminum raw materials, prepare aluminum alloys, and cast them into aluminum alloy ingots. The fuel is natural gas, and the maximum heat output is 300m³ of natural gas. 3 / per hour. Continuous production is 3 furnaces per day, with one furnace constituting one production cycle. The heating process within one production cycle takes 5 hours, while other processes such as feeding, slag removal, refining, and casting take approximately 3 hours. One production cycle consists of the following steps: Low-temperature stage: solid aluminum at room temperature to 660℃; Melting stage: around 660℃; Medium-temperature stage: liquid aluminum at 660℃ to 710-730℃; Slag removal and refining (alloy preparation); High-temperature stage: further heating to 740-760℃; Casting. Throughout the process, in this embodiment, the aluminum melting furnace, in addition to the combustion products—flue gas—discharged during combustion system operation, also emits complex dust from the material during the high-temperature stage. During slag removal and refining, the combustion system is not operating, but the industrial furnace emits a large amount of corrosive gases. Dust and corrosive gases can easily damage the detection unit in the gas composition detection device.

[0027] If no measures are taken, the dust and corrosive gases emitted will naturally enter the gas composition detection device through the gas sampling probe when they flow through the exhaust pipe, causing blockage and serious damage to the detection unit inside the gas composition detection device, rendering it unable to work within a few days.

[0028] like Figure 3 As shown, the gas composition detection device 13 includes a detection unit 131, an actuator 132, and a valve 133. The detection unit 131 includes a gas sampling probe 1311, a sampling gas pump, and a composition analysis module. The gas sampling probe 1311 is connected to the composition analysis module through the sampling gas pump. The actuator 132 includes a telescopic mechanism 1322 and a telescopic rod 1323. The gas sampling probe 1311 has an air inlet and is fixed to the telescopic rod 1323. The gas sampling probe 1311 and the telescopic rod 1323 are located inside a protective box 1324. The protective box is connected to the sampling port 1321 through the valve 133. The sampling port 1321 is connected to the exhaust pipe 12.

[0029] When the angle between the centerline of the sampling port 1321 and the flow direction of the exhaust gas 14 is greater than or equal to 90 degrees, according to the principle of fluid mechanics, the flow of the flue gas 14 will generate a slight negative pressure in the protective box. When the gas sampling probe 1311 retracts into the protective box 1324 and is in the recovery or closed state, the flue gas 14 will not enter the protective box 1324. At this time, valve 133 can be used or not.

[0030] In this embodiment, the component analysis module of the detection unit 131 can analyze four components: O2, CO, NO, and NO2. The gas component detection device 13 operates intermittently, performing one test per week, with each sampling lasting 5 minutes. The test is conducted at a medium temperature. During the test, the control system opens valve 133, the component analysis module, and the sampling gas pump. Then, the control system activates the telescopic mechanism 1322, driving the telescopic rod 1323 to extend, allowing the gas sampling probe 1311 to pass through valve 133 and sampling port 1321 and enter the exhaust pipe 12. The gas sampling probe 1311 extracts a sample from the flue gas 14 and delivers it to the component analysis module. The component analysis module analyzes the components of the flue gas 14. Five minutes later, the control system starts the telescopic machine 1322, drives the telescopic rod 1323 to retract, closes the valve 133, and stops the component analysis module and sampling gas pump. The gas sampling probe 1311 is isolated from dust and corrosive gases in the protective box 1324, so that the detection unit 131 can maintain a good condition for a long time and ensure its long service life.

[0031] Example 2

[0032] like Figure 4-5 As shown, this embodiment is a 135-ton horizontal ladle heater with a diameter of 4.0 meters. Its purpose is to heat the inner lining of the ladle to 900℃-1000℃ for use in steel smelting production. The fuel is coal gas with a calorific value of 1800 kcal / Nm³. 3 During the high-temperature phase, the heating power is 1500m³ of coal gas. 3 / The time it takes for the small repair tank to heat up to 1000℃ is 6 hours, and the holding time after reaching 1000℃ is 6 hours.

[0033] The structure of the ladle baking process is similar to that of Example 1, with the following differences: ① The furnace chamber 1 consists of the ladle cover 16 and the ladle 17 of the baking unit; ② A return fan 72 is added to the flue gas return pipe 7 to provide power for flue gas return. ③ The main problem during ladle baking is that a large amount of carbon is released from the magnesia-carbon refractory bricks lining the ladle at around 400°C during the heating process, producing combustible black smoke, which seriously affects the air-fuel ratio of the combustion system and causes a sharp increase in CO content. Therefore, in this example, the component analysis module can use both O2 and CO. The control system adjusts the system operating parameters in a timely manner based on the changes in these two components.

[0034] For those skilled in the art, various corresponding changes and modifications can be made based on the above technical solutions and concepts, and all such changes and modifications should be included within the protection scope of the claims of this invention.

Claims

1. An energy-saving and environmentally friendly combustion system, comprising a furnace, several heat storage boxes, burners, an inlet pipe, an exhaust pipe, a blower, an induced draft fan, an airflow reversing system, a flue gas recirculation pipe, and a control system; the furnace has several air inlets, the number of which corresponds to the number of heat storage boxes, and each air inlet of the furnace is connected to one heat storage box; a blower is installed on the inlet pipe, and an induced draft fan is installed on the exhaust pipe; the airflow reversing system has several switching ports, which are respectively connected to the inlet pipe, the exhaust pipe, and each heat storage box; a gas composition detection device is installed on the exhaust pipe; characterized in that: The gas composition detection device includes a detection unit, an actuator, a protective box, and a sampling port. The detection unit includes a gas sampling probe, a sampling gas pump, and a composition analysis module. The gas sampling probe is connected to the composition analysis module through the sampling gas pump. The actuator includes a telescopic mechanism and a telescopic rod. The gas sampling probe has an air inlet and is fixed to the telescopic rod. Both the gas sampling probe and the telescopic rod are located inside the protective box. The protective box is connected to the sampling port, and the sampling port is connected to an exhaust pipe. The airflow reversing system includes a four-way valve; It also includes a flue gas return pipe, one end of which is connected to the exhaust pipe and the other end is connected to the intake pipe, and a flue gas return valve is provided on the flue gas return pipe.

2. The energy-saving and environmentally friendly combustion system according to claim 1, characterized in that, The flue gas return pipe is also equipped with a return fan.

3. An industrial furnace having the energy-saving and environmentally friendly combustion system as described in any one of claims 1-2.

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