Air-fuel ratio control system for high-temperature forging heating furnace

Abstract

The utility model discloses an air-fuel ratio control system for a high-temperature forging heating furnace, relates to the technical field of forging heating furnaces, and can solve the problem of poor control effect on the oxygen content of a hearth in the high-temperature forging heating furnace in the prior art. The air-fuel ratio control system for the high-temperature forging heating furnace comprises a plurality of combustion modules, each combustion module comprises a gas pipeline, an air pipeline, a first proportional valve and a second proportional valve, the first proportional valve and the second proportional valve are sequentially arranged on the gas pipeline in the gas flowing direction, and the first proportional valve is communicated with the air pipeline; the system further comprises a signal gas pipeline and a pressure regulating valve arranged on the signal gas pipeline, the second proportional valve is communicated with the signal gas pipeline, and the communication point is located on the upstream of the pressure regulating valve.

Description

Technical Field

[0001] This utility model relates to the field of forging heating furnace technology, specifically to an air-fuel ratio control system for a high-temperature forging heating furnace. Background Technology

[0002] For some high-temperature forging furnaces, the furnace temperature is generally close to 1200℃. Under such high-temperature conditions, metals are easily oxidized, resulting in very serious oxidation loss. This is especially true for high-end aerospace materials, where the losses are even greater due to the high cost of the materials. In addition to greater burn-off, the uneven oxidation of these forgings within the high-temperature furnace results in poor surface smoothness after removing the iron oxide scale. This further increases the cost of subsequent processing and the cutting losses during machining.

[0003] The main reason for this high-temperature oxidation is that the oxygen content in the furnace cannot be effectively controlled. This is because most forging furnaces on the market use pulse combustion control to ensure uniform furnace temperature. Furthermore, to save energy, heat recovery is achieved by preheating the combustion air with flue gas. Therefore, most high-temperature forging furnaces on the market use a pulse combustion control mode with preheated air. Because the forging furnace operates periodically or the furnace door is opened intermittently, the furnace temperature varies, causing the air preheating temperature to also vary. This makes it difficult to precisely control the air-fuel ratio of a single burner during pulse combustion, resulting in difficulty controlling the oxygen content in the furnace to a low level.

[0004] Based on the above background, the inventors designed an air-fuel ratio control system for a high-temperature forging heating furnace to solve at least one of the above problems, and hereby submit this application. Summary of the Invention

[0005] The purpose of this application is to provide an air-fuel ratio control system for a high-temperature forging heating furnace, which solves the problem of poor control of oxygen content in the furnace chamber of a high-temperature forging heating furnace in the prior art.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following solution:

[0007] This application provides an air-fuel ratio control system for a high-temperature forging heating furnace, comprising several sets of combustion modules. Each set of combustion modules includes a gas pipeline and an air pipeline, as well as a first proportional valve and a second proportional valve sequentially arranged on the gas pipeline along the gas flow direction, wherein:

[0008] The first proportional valve is connected to the air duct;

[0009] It also includes a signal gas pipeline and a pressure regulating valve installed on the signal gas pipeline. The second proportional valve is connected to the signal gas pipeline, and the connection point is located upstream of the pressure regulating valve.

[0010] Optionally, an air fine-tuning valve and a gas fine-tuning valve are also respectively installed on the gas pipeline and the air pipeline;

[0011] The gas fine-tuning valve is located downstream of the first proportional valve and the second proportional valve along the gas flow direction, and the air fine-tuning valve is located downstream of the connection point between the first proportional valve and the air pipeline.

[0012] Optionally, the system also includes burners in the same number as the combustion modules, with the gas inlet of the burner connected to the gas outlet of the gas pipeline and the air inlet of the burner connected to the air outlet of the air pipeline.

[0013] Optionally, the combustion module further includes a pulse solenoid valve and a pulse switching valve respectively disposed on the gas pipeline and the air pipeline;

[0014] The pulse solenoid valve is located upstream of the first proportional valve along the gas flow direction, and the pulse switching valve is located upstream of the connection point between the first proportional valve and the air pipeline along the air flow direction.

[0015] Optionally, the combustion module further includes a first pressure guide pipe and a second pressure guide pipe, wherein the first proportional valve is connected to the air pipe through the first pressure guide pipe, and the second proportional valve is connected to the signal gas pipe through the second pressure guide pipe.

[0016] Optionally, it also includes a flue gas duct for discharging flue gas from the furnace, and an online oxygen content analyzer is installed in the flue gas duct for real-time measurement of the oxygen content in the flue gas.

[0017] Optionally, it also includes a heat exchanger for transferring heat from the flue gas to the combustion air, with one end of the heat exchanger installed on the flue gas duct.

[0018] Optional features also include a main gas pipe and a main air pipe, as well as a pressure regulating and shut-off valve station and a combustion fan;

[0019] The gas pipeline of each combustion module is connected to the pressure regulating and shut-off valve station through the gas main pipe, and the air pipeline is connected to the combustion fan through the air main pipe.

[0020] The air main pipe runs through and is installed at the other end of the heat exchanger.

[0021] Optionally, a second thermocouple may also be included for installation inside the furnace to monitor the furnace temperature in real time.

[0022] The beneficial effects of this utility model are:

[0023] 1. A signal gas is set up and its pressure is controlled by a pressure regulating valve. This allows for reverse control of the opening of the second proportional valve before each burner. Under the same combustion air mass flow rate, this can offset the disturbance to the gas flow rate caused by pressure fluctuations in the first proportional valve before each burner due to the increase or decrease in combustion air temperature.

[0024] Second, by setting up an online oxygen content analyzer, the opening degree of the signal gas flow regulating valve can be corrected using the online oxygen content measured by the online oxygen content analyzer, thereby improving the accuracy of furnace oxygen content control. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the connection relationship in an embodiment of this application.

[0026] Explanation of reference numerals in the attached diagram: 1-Pressure regulating and shut-off valve station, 2-Pressure regulating valve, 3-Pulse switching valve, 4-Pulse solenoid valve, 5-First proportional valve, 6-Second proportional valve, 7-Gas fine-tuning valve, 8-Air fine-tuning valve, 9-Burn, 10-First thermocouple, 11-Online oxygen content analyzer, 12-Combustion fan, 13-Second thermocouple, 14-Heat exchanger, 15-Chimney, A-Signal gas emission port, B-Smoke exhaust port. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0028] In the description of this utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "longitudinal", "lateral", "horizontal", "inner", "outer", "front", "rear", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the utility model product is in use. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0029] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set up," "have," "install," "connect," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0030] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0031] like Figure 1 As shown, this embodiment provides an air-fuel ratio control system for a high-temperature forging heating furnace, including several sets of combustion modules. Each combustion module includes a gas pipeline and an air pipeline, as well as a first proportional valve 5 and a second proportional valve 6 sequentially arranged on the gas pipeline along the gas flow direction, wherein:

[0032] The first proportional valve 5 is connected to the air duct;

[0033] It also includes a signal gas pipeline and a pressure regulating valve 2 installed on the signal gas pipeline. The second proportional valve 6 is connected to the signal gas pipeline, and the connection point is located upstream of the pressure regulating valve 2.

[0034] In this embodiment, a first proportional valve 5 and a second proportional valve 6 are installed on the gas pipeline, along with a signal gas pipeline and a pressure regulating valve 2. The first proportional valve 5 is connected to the air pipeline, and the second proportional valve 6 is connected to the signal gas pipeline. The pressure of the signal gas can be used to control the opening of the second proportional valve 6 in reverse, thereby offsetting the pressure fluctuations in the first proportional valve 5 before each burner 9 caused by the increase or decrease of the combustion air temperature, which disturbs the gas flow and ensures that the air-fuel ratio of the burner 9 is always controlled in a stable state.

[0035] In this embodiment, as Figure 1 As shown, an air fine-tuning valve 8 and a gas fine-tuning valve 7 are respectively installed on the gas pipeline and the air pipeline;

[0036] The gas fine-tuning valve 7 is located downstream of the first proportional valve 5 and the second proportional valve 6 along the gas flow direction, and the air fine-tuning valve 8 is located downstream of the connection point between the first proportional valve 5 and the air pipeline. In this embodiment, both the air fine-tuning valve 8 and the gas fine-tuning valve 7 can be manual valves.

[0037] In this embodiment, as Figure 1 As shown, it also includes burners 9 in the same number as the combustion modules. The gas inlet end of the burner 9 is connected to the gas outlet end of the gas pipeline, and the air inlet end of the burner 9 is connected to the air outlet end of the air pipeline.

[0038] In this embodiment, as Figure 1 As shown, the combustion module also includes a pulse solenoid valve 4 and a pulse switching valve 3 respectively installed on the gas pipeline and the air pipeline;

[0039] The pulse solenoid valve 4 is located upstream of the first proportional valve 5 along the gas flow direction, and the pulse switching valve 3 is located upstream of the connection point between the first proportional valve 5 and the air pipeline along the air flow direction. The pulse solenoid valve 4 and the pulse switching valve 3 are used to control the opening and closing of the gas pipeline and the air pipeline, respectively.

[0040] In this embodiment, as Figure 1 As shown, the combustion module also includes a first pressure-conducting pipe and a second pressure-conducting pipe. The first proportional valve 5 is connected to the air pipe through the first pressure-conducting pipe, and the second proportional valve 6 is connected to the signal gas pipe through the second pressure-conducting pipe. Figure 1 In the diagram, both the first and second pressure-conducting tubes are represented by dashed lines.

[0041] In this embodiment, as Figure 1 As shown, it also includes a flue gas duct for discharging flue gas from the furnace, and an online oxygen content analyzer 11 for real-time measurement of the oxygen content in the flue gas is installed in the flue gas duct.

[0042] In this embodiment, to more accurately control the oxygen content in the furnace, the system also uses an online oxygen analyzer 11 installed on the combustion exhaust duct to correct the air-fuel ratio of all burners 9 in real time. When the online oxygen analyzer 11 in the duct measures an oxygen concentration higher than the set oxygen concentration, it reduces the opening of the signal gas pressure regulating valve 2, increasing the signal gas pressure. The opening of the second proportional valve 6 increases, allowing more fuel gas to enter the operating burners 9, reducing the excess oxygen coefficient of all operating burners 9, thereby ensuring a decrease in the oxygen concentration in the furnace and bringing the oxygen concentration in the exhaust combustion gas close to the set oxygen concentration. When the online oxygen analyzer 11 measures an oxygen concentration lower than the set oxygen concentration, it increases the opening of the signal gas pressure regulating valve 2, decreasing the signal gas pressure. The opening of the second proportional valve 6 decreases, allowing less fuel gas to enter the operating burners 9, thereby increasing the excess oxygen coefficient of all operating burners 9, thus ensuring an increase in the oxygen concentration in the furnace and bringing the oxygen concentration in the exhaust combustion gas close to the set oxygen concentration.

[0043] In this embodiment, as Figure 1 As shown, it also includes a heat exchanger 14 for transferring heat from the flue gas to the combustion air, with one end of the heat exchanger 14 installed on the flue gas duct.

[0044] In this embodiment, as Figure 1 As shown, it also includes a gas main pipe and an air main pipe, as well as a pressure regulating and shut-off valve station 1 and a combustion fan 12;

[0045] The gas pipeline of each combustion module is connected to the pressure regulating and shut-off valve station 1 through the gas main pipe, and the air pipeline is connected to the combustion fan 12 through the air main pipe.

[0046] An air main pipe runs through and is installed at the other end of the heat exchanger 14. In this embodiment, the pressure regulating shut-off valve station 1 and the combustion air blower 12 are used to supply fuel gas and combustion air, respectively.

[0047] In this embodiment, as Figure 1As shown, it also includes a second thermocouple 13 for installation inside the furnace to monitor the furnace temperature in real time, which facilitates the control of the real-time temperature inside the furnace.

[0048] In this embodiment, a chimney 15 is also provided, and a flue gas pipe is connected to the chimney 15. After heat exchange, the flue gas can be discharged from the chimney 15. In this embodiment, a signal gas discharge port A is provided at one end of the signal gas pipe near the pressure regulating valve 2. The signal gas can be nitrogen.

[0049] The workflow of this embodiment is as follows:

[0050] When the control system in this embodiment starts the cold furnace, the pressure regulating valve 2 of the signal gas will be placed at a very small opening position, and the pressure of the signal gas will be high, so that the second proportional valve 6 before each burner 9 is in the fully open state, the shut-off valve of the pressure regulating shut-off valve station 1 is opened, and then the air pulse switch valve 3 and the gas pulse solenoid valve 4 before each burner 9 are opened in sequence to ignite the corresponding burner 9. After all burners 9 are ignited, the gas fine adjustment valve 7 and the air fine adjustment valve 8 before each burner 9 are precisely adjusted to make the air-fuel ratio of each burner 9 reasonable, and the power of each burner 9 is basically the same.

[0051] Once each burner 9 is operational, the temperature of the flue gas discharged from exhaust port B gradually increases. Through the heat exchange of heat exchanger 14, the temperature of the combustion air measured by the thermocouple after heat exchanger 14 will increase. As the temperature of the combustion air increases, the air expands, and the pressure of the combustion air in front of burner 9 will increase. This causes the opening of the first proportional valve 5 in front of each burner 9 to increase, allowing more gas to flow downstream through the first proportional valve 5. However, as the temperature of the combustion air increases, the opening of the signal gas pressure regulating valve 2 will increase, and the signal gas pressure upstream of the pressure regulating valve 2 will decrease. This causes the opening of the second proportional valve 6 in front of each burner 9 to decrease, thus limiting the flow of more gas from the second proportional valve 6 into the downstream burner 9.

[0052] Therefore, when the combustion air temperature rises, the opening of the second proportional valve 6 decreases, offsetting the increased gas flow caused by the increased opening of the first proportional valve 5. Conversely, when the combustion air temperature decreases, the pressure before the burner 9 decreases for the same mass flow rate of combustion air, resulting in a decrease in the opening of the first proportional valve 5. This leads to a smaller opening for the signal gas pressure regulation, causing an increase in the upstream signal gas pressure. Consequently, the opening of the second proportional valve 6 before each burner 9 increases, which in turn offsets the decrease in flow rate caused by the decrease in the opening of the first proportional valve 5. Therefore, this application can, under the same combustion air mass flow rate conditions, offset the pressure fluctuations in the first proportional valve 5 before each burner 9 caused by the rise or fall of combustion air temperature, thus keeping the air-fuel ratio within a reasonable range and effectively solving the problem of difficult air-fuel ratio control in high-temperature forging furnaces in the prior art.

[0053] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of this utility model, and the utility model is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of this utility model, and these modifications and improvements are also considered to be within the protection scope of this utility model.

Claims

1. An air-fuel ratio control system for a high-temperature forging heating furnace, characterized in that, It includes several sets of combustion modules, each set of combustion modules including a gas pipeline and an air pipeline, and a first proportional valve (5) and a second proportional valve (6) sequentially arranged on the gas pipeline along the gas flow direction, wherein: The first proportional valve (5) is connected to the air duct; It also includes a signal gas pipeline and a pressure regulating valve (2) installed on the signal gas pipeline. The second proportional valve (6) is connected to the signal gas pipeline, and the connection point is located upstream of the pressure regulating valve (2).

2. The air-fuel ratio control system for a high-temperature forging heating furnace according to claim 1, characterized in that, The gas pipeline and the air pipeline are also respectively equipped with an air fine adjustment valve (8) and a gas fine adjustment valve (7); The gas fine adjustment valve (7) is located downstream of the first proportional valve (5) and the second proportional valve (6) along the gas flow direction, and the air fine adjustment valve (8) is located downstream of the connection point between the first proportional valve (5) and the air pipeline.

3. The air-fuel ratio control system for a high-temperature forging heating furnace according to claim 2, characterized in that, It also includes burners (9) in the same number as the combustion modules. The gas inlet of the burner (9) is connected to the gas outlet of the gas pipeline, and the air inlet of the burner (9) is connected to the air outlet of the air pipeline.

4. The air-fuel ratio control system for a high-temperature forging heating furnace according to claim 1, characterized in that, The combustion module also includes a pulse solenoid valve (4) and a pulse switching valve (3) respectively installed on the gas pipeline and the air pipeline; The pulse solenoid valve (4) is located upstream of the first proportional valve (5) along the gas flow direction, and the pulse switching valve (3) is located upstream of the connection point between the first proportional valve (5) and the air pipeline along the air flow direction.

5. The air-fuel ratio control system for a high-temperature forging heating furnace according to claim 1, characterized in that, The combustion module also includes a first pressure guide pipe and a second pressure guide pipe. The first proportional valve (5) is connected to the air pipe through the first pressure guide pipe, and the second proportional valve (6) is connected to the signal gas pipe through the second pressure guide pipe.

6. The air-fuel ratio control system for a high-temperature forging heating furnace according to claim 1, characterized in that, It also includes a flue gas duct for discharging flue gas from the furnace, and an online oxygen content analyzer (11) is installed in the flue gas duct for real-time measurement of the oxygen content in the flue gas.

7. The air-fuel ratio control system for a high-temperature forging heating furnace according to claim 6, characterized in that, It also includes a heat exchanger (14) for transferring heat from the flue gas to the combustion air, one end of which is mounted on the flue gas duct.

8. The air-fuel ratio control system for a high-temperature forging heating furnace according to claim 7, characterized in that, It also includes a gas main and an air main, as well as a pressure regulating and shut-off valve station (1) and a combustion fan (12); The gas pipeline of each combustion module is connected to the pressure regulating and shut-off valve station (1) through the gas main pipe, and the air pipeline is connected to the combustion fan (12) through the air main pipe; The air main pipe runs through and is installed at the other end of the heat exchanger (14).

9. The air-fuel ratio control system for a high-temperature forging heating furnace according to claim 1, characterized in that, It also includes a second thermocouple (13) for installation inside the furnace to monitor the furnace temperature in real time.

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