System for adjusting hearth pressure of heating furnace and adjusting valve

Abstract

The utility model discloses a system for adjusting the hearth pressure of a heating furnace and an adjusting valve, relates to the technical field of industrial furnaces, and aims to solve the problem that a smoke exhaust system needs to be improved to realize wide-range hearth pressure adjustment. A furnace tail of a heating furnace is connected to a smoke inlet of a heat exchanger through a furnace tail smoke exhaust pipe, a branch pipe is arranged on the furnace tail smoke exhaust pipe and used for being connected with a mixed cooling fan, a smoke outlet of the heat exchanger is connected to an induced draft fan through a rear smoke exhaust pipeline, and a furnace pressure adjusting valve is installed on a pipeline of the rear smoke exhaust pipeline. A cold mixing branch pipe is connected to a pipeline between the furnace pressure regulating valve and the induced draft fan and is used for connecting a cold air mixing valve; a front temperature measuring element is arranged on the furnace tail smoke exhaust pipeline and located at the front end of the heat exchanger, and an induced draft fan temperature measuring element is arranged on the pipeline between the furnace pressure adjusting valve and the induced draft fan. The device is simple, reasonable, easy to implement, sensitive in adjustment, high in precision, wide in application range and capable of achieving wide-range precise adjustment of the hearth pressure.

Description

Technical Field

[0001] The utility model relates to the technical field of industrial furnaces, in particular to a system and a regulating valve for regulating the furnace pressure of a heating furnace. Background Art

[0002] With the development of steel rolling technology, the technical indicators of heating furnaces are required to be higher and higher, such as higher billet heating quality requirements, energy saving and consumption reduction, environmental protection, etc. These high requirements have led to the iterative update of heating furnace combustion systems and their control methods. For example, pulse control is applied to conventional combustion systems. In actual application, pulse control has played a positive role in improving thermal efficiency and improving the uniformity of temperature field in the furnace. However, due to the discontinuity of pulse combustion, the furnace pressure will be unstable. For heating furnaces that use heat storage combustion, due to the heat storage reversing combustion method, each reversal has a very obvious impact on the furnace pressure of the heating furnace, resulting in a large range of furnace pressure fluctuations. Under this background, improving the furnace pressure control accuracy of the heating furnace has become a difficult problem.

[0003] The utility model patent, published with announcement number CN211645345U and titled "Dynamic Optimization Control System for Furnace Pressure of Heating Furnace Based on Furnace Gas Volume," discloses a scheme for adjusting the induced draft fan inlet valve and fan speed based on furnace gas volume and furnace pressure. However, the inlet valve is a valve of the induced draft fan itself, designed to match the furnace gas volume, and the induced draft fan speed adjustment has not been practically improved. This makes adjustment difficult when faced with a wide range of furnace pressure fluctuations. In recent years, with the development of the domestic economy, demand for specialty steel has increased significantly across various industries, and the special steel industry has become a key foundation for the development of my country's manufacturing industry. For heating furnaces deployed in special steel production lines, the furnace pressure varies with the wide range of production, increasing the adjustment range. This places high demands on achieving precise furnace pressure adjustment over a wide range. Therefore, a system and regulating valve for adjusting the furnace pressure of a heating furnace are urgently needed to address this problem. Utility Model Content

[0004] The purpose of the utility model is to provide a system and a regulating valve for regulating the furnace pressure of a heating furnace, so as to solve the problem that the smoke exhaust system needs to be improved in order to achieve a wide range of furnace pressure regulation.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a system for regulating the furnace pressure of a heating furnace, which is arranged at the tail of the heating furnace, and includes a cold air blower, a heat exchanger, a furnace pressure regulating valve, a cold air blower valve and an induced draft fan; the tail of the heating furnace is connected to the flue gas inlet of the heat exchanger through a furnace tail exhaust pipe, and a branch pipe is provided on the furnace tail exhaust pipe for connecting to the cold air blower, and the flue gas outlet of the heat exchanger is connected to the induced draft fan through a rear exhaust pipe, and the furnace pressure regulating valve is installed on the pipeline of the rear exhaust pipe, and a cold air blower branch pipe is connected to the pipeline between the furnace pressure regulating valve and the induced draft fan for connecting to the cold air blower valve; a front temperature measuring element is provided on the furnace tail exhaust pipe at the front end of the heat exchanger, and an induced draft fan temperature measuring element is provided on the pipeline between the furnace pressure regulating valve and the induced draft fan.

[0006] Preferably, a rear temperature measuring element is provided on the rear exhaust pipe at the rear end of the heat exchanger, and an induced draft fan pressure measuring element is also provided on the pipeline between the furnace pressure regulating valve and the induced draft fan; the induced draft fan outlet pipeline is connected to a steel chimney.

[0007] Preferably, the outer periphery of the rear smoke exhaust duct is wrapped with an insulating environmentally friendly blanket.

[0008] Another technical solution provided by the present invention is: a regulating valve for regulating the furnace pressure of a heating furnace, the furnace pressure regulating valve is a rotary plate valve without an insulating lining, which includes a steel pipe and flanges at both ends for connecting pipelines, a support is fixedly provided on the outside of the steel pipe, the support is rotatably connected to a rotating shaft perpendicular to the steel pipe, the rotating shaft passes through the outer wall of the steel pipe, and a valve plate is fixedly connected inside the steel pipe, and the inner wall of the steel pipe is respectively fixed with semicircular ring blocks on both sides of the rotating shaft, the ring blocks are perpendicular to the steel pipe, and the two ring blocks are respectively located on both sides of the valve plate; the diameter of the valve plate is smaller than the inner diameter of the steel pipe, and the sum of the width of the ring block and the diameter of the valve plate is greater than the inner diameter of the steel pipe.

[0009] Preferably, a plurality of ribs are fixedly provided on both sides of the ring baffle for reinforcement, and the ribs are fixedly connected to the inner wall of the steel pipe.

[0010] Preferably, the inner diameter of the furnace pressure regulating valve is smaller than the inner diameter of the rear smoke exhaust pipe.

[0011] Compared with the prior art, the beneficial effects of the present invention are:

[0012] 1. The system for adjusting the hearth pressure of a heating furnace has a simple and reasonable structure, sensitive adjustment, high precision, a wide range of applications, and can adapt to large changes in hearth pressure. It can be used for heating furnaces on steel rolling production lines with different combustion systems, such as heating furnaces with regenerative combustion systems that burn low-calorific value gas, and heating furnaces with conventional combustion systems that burn higher-calorific value gas; it can be used for heating furnaces with dual-cross limiting control in the combustion system, and it can also be used for heating furnaces with pulse control in the combustion system. It is especially suitable for heating furnaces for heating various types of steel, because the output of various types of steel heating furnaces varies widely, the hearth pressure varies with changes in output, and the adjustment range becomes larger. The application of this adjustment method can achieve wide-range and precise adjustment.

[0013] 2. The regulating valve used to adjust the furnace pressure of the heating furnace adopts a special non-insulated lining structure and replaces the original insulating valve seat with a ring block. There is no need to cast refractory materials inside the valve pipe. Compared with the traditional flue valve structure, it is simpler and lighter than the traditional flue rotary gate valve with internal insulation. It has a short manufacturing cycle, is easy to inspect and maintain, and has low maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a system diagram of the furnace pressure regulation method of the present utility model;

[0015] Figure 2 This is a schematic diagram of the main structure of the furnace pressure regulating valve of the utility model;

[0016] Figure 3 for Figure 2 The schematic diagram of the top cross-sectional structure of the furnace pressure regulating valve is shown.

[0017] In the figure: 100, heating furnace; 101, furnace tail exhaust pipe; 102, cooling air blower; 103, heat exchanger; 104, rear exhaust pipe; 105, furnace pressure regulating valve; 106, cooling air valve; 107, induced draft fan; 108, steel chimney; 109, front temperature measuring element; 110, rear temperature measuring element; 111, induced draft fan temperature measuring element; 112, induced draft fan pressure measuring element;

[0018] 1. Rotating shaft; 2. Valve plate; 3. Support; 4. Flange 1; 5. Flange 2; 6. Bolted connector; 7. Steel pipe; 8. Ring stop; 9. Rib plate. DETAILED DESCRIPTION

[0019] The method provided by the present invention can be used for heating furnaces on steel rolling production lines with different combustion systems, such as heating furnaces with a regenerative combustion system that burns low-calorific value coal gas, and heating furnaces with a conventional combustion system that burns higher-calorific value coal gas; it can be used for heating furnaces with a combustion system that adopts double cross-limiting control, and can also be used for heating furnaces with a combustion system that adopts pulse control; specifically, a method for regulating the furnace pressure of a heating furnace according to the present invention comprises the following contents: a smoke exhaust pipe is provided at the tail of the heating furnace to lead the smoke in the furnace out of the furnace, and the temperature of the smoke discharged from the furnace is reduced to below the target temperature through an air heat exchanger, and an air cooler is provided in front of the air heat exchanger for protection, and the air cooler is interlocked with the smoke temperature in front of the heat exchanger, and the efficiency of the air heat exchanger is such that the smoke temperature can be reduced under normal working conditions. The temperature is lowered to below the target temperature. An air heat exchanger can be used to recover as much waste heat from the flue gas as possible to preheat the air, while reducing the flue gas temperature after the heat exchanger to below the target temperature, which can reduce heat loss. A pneumatic furnace pressure regulating valve is set on the flue gas outlet pipe of the heat exchanger, and the flue gas outlet end of the furnace pressure regulating valve is connected to an induced draft fan that can adjust the exhaust air volume. A furnace pressure detection element is set on the top of the heating furnace's soaking section. The exhaust air volume of the induced draft fan and the opening of the furnace pressure regulating valve are adjusted according to the furnace pressure value. For reference only, the furnace pressure is roughly adjusted by adjusting the induced draft fan air volume, and the furnace pressure is fine-tuned by the furnace pressure regulating valve. This method has sensitive adjustment and high precision. A cold air branch pipe is also connected to the pipeline between the furnace pressure regulating valve and the induced draft fan, and a cold air valve is provided on the branch pipe, and its opening is interlocked with the flue gas temperature before the induced draft fan.

[0020] The flue gas is drawn out from the tail of the heating furnace and can be used to preheat the billets located in the tail of the heating furnace; the use of induced draft fans for mechanical smoke exhaust can avoid the problem of large chimney footprint caused by natural smoke exhaust.

[0021] For reference, for example, if the above target temperature is 350℃, the cold air fan and the cold air valve will be opened when the flue gas temperature before the heat exchanger and the flue gas temperature before the induced draft fan are respectively higher than 350℃, and the air volume of the cold air fan and the opening of the cold air valve can be adjusted according to the degree of overtemperature; among them, the air volume of the induced draft fan and the cold air fan can be adjusted by frequency conversion.

[0022] To implement the above method, see Figure 1The utility model is a heating furnace pressure regulating system, which is arranged at the tail of the heating furnace 100, and includes a cooling air blower 102, a heat exchanger 103, a furnace pressure regulating valve 105, a cooling air blower valve 106 and an induced draft fan 107; the tail of the heating furnace 100 is connected to the flue gas inlet of the heat exchanger 103 through the tail exhaust pipe 101, and the tail exhaust pipe 101 is provided with a branch pipe for connecting to the cooling air blower 102, and the flue gas outlet of the heat exchanger 103 passes through the tail exhaust pipe 101. The smoke exhaust pipe 104 is connected to the induced draft fan 107, and the furnace pressure regulating valve 105 is installed on the pipeline of the rear smoke exhaust pipe 104. A cold air branch pipe is connected to the pipeline between the furnace pressure regulating valve 105 and the induced draft fan 107 for connecting the cold air valve 106; a front temperature measuring element 109 is provided at the front end of the heat exchanger 103 on the pipeline of the furnace tail smoke exhaust pipe 101, and an induced draft fan temperature measuring element 111 is provided on the pipeline between the furnace pressure regulating valve 105 and the induced draft fan 107.

[0023] In addition, a rear temperature measuring element 110 can be provided on the rear exhaust duct 104 at the rear end of the heat exchanger 103 to observe whether the heat exchange effect meets expectations. An induced draft fan pressure measuring element 112 can also be provided on the pipeline between the furnace pressure regulating valve 105 and the induced draft fan 107, and the pressure information at this position can be used to reflect whether the operation is stable; the outlet pipeline of the induced draft fan 107 is connected to a steel chimney 108; the outer periphery of the rear exhaust duct 104 is wrapped with an insulating environmentally friendly blanket.

[0024] The temperature measuring elements and pressure measuring elements mentioned above can generally be realized by conventional online thermometers and pressure gauges. It is well known that the interlocking method is to transmit data to a controller, such as a PLC, through the temperature measuring elements and pressure measuring elements. The controller then makes judgments and issues instructions according to the set program to control the induced draft fan, furnace pressure regulating valve, cold air valve, and the actuating mechanism of the cold air valve.

[0025] See Figure 2 and 3 In a preferred embodiment, the furnace pressure regulating valve 105 of the present invention adopts a specially designed structure, which is generally similar to a rotary disc valve, but does not require an insulating lining, has a simple structure, is lighter than a traditional flue rotary gate valve with internal insulation, has a short manufacturing cycle, is easy to inspect and maintain, and has low maintenance costs. Specifically, it includes a steel pipe 7 and flanges at both ends for connecting pipelines. A support 3 is fixed to the outside of the steel pipe 7, and the support 3 is rotatably connected to a rotating shaft 1 perpendicular to the steel pipe 7. The rotating shaft 1 passes through the outer wall of the steel pipe 7 and is fixedly connected to a valve plate 2 inside the steel pipe 7. Semicircular ring blocks 8 are fixed on both sides of the inner wall of the steel pipe 7. The ring blocks 8 are perpendicular to the steel pipe 7, and the two ring blocks 8 are respectively located on both sides of the valve plate 2; the diameter of the valve plate 2 is smaller than the inner diameter of the steel pipe 7, and the sum of the width of the ring block 8 and the diameter of the valve plate 2 is greater than the inner diameter of the steel pipe 7.

[0026] To strengthen the connection, further optionally, a plurality of ribs 9 are fixedly provided on both sides of the ring baffle 8 , and the ribs 9 are fixedly connected to the inner wall of the steel pipe 7 .

[0027] Usually, the inner diameter of the furnace pressure regulating valve 105 can be made equal to the inner diameter of the rear exhaust pipe 104 . However, in order to increase the regulation sensitivity, the inner diameter of the furnace pressure regulating valve 105 can be made smaller than the inner diameter of the rear exhaust pipe 104 .

[0028] The above-mentioned furnace pressure regulation method and system were applied to a heating furnace for heating grade steel for long-term testing. Due to the large output variation range of the grade steel heating furnace and the wide range of furnace pressure variation with output, the furnace pressure needs to be adjusted by a large range. Under this relatively harsh test condition, the furnace pressure is basically maintained within the variation range of ±10Pa, which well meets the requirements of sensitive and high-precision furnace pressure regulation.

[0029] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection defined by the claims.

[0030] Anything not described in detail in the present invention is well known to those skilled in the art.

Claims

1. A system for regulating the furnace pressure of a heating furnace, arranged at the furnace tail of a heating furnace (100), characterized in that: The heating furnace (100) comprises a cooling air blower (102), a heat exchanger (103), a furnace pressure regulating valve (105), a cooling air blower valve (106) and an induced draft fan (107); the tail of the heating furnace (100) is connected to the flue gas inlet of the heat exchanger (103) through a tail flue gas exhaust pipe (101); a branch pipe is provided on the tail flue gas exhaust pipe (101) for connecting to the cooling air blower (102); the flue gas outlet of the heat exchanger (103) is connected to the induced draft fan (107) through a rear flue gas exhaust pipe (104). The furnace pressure regulating valve (105) is installed on the pipeline of the rear exhaust pipe (104), and a cold air branch pipe is connected to the pipeline between the furnace pressure regulating valve (105) and the induced draft fan (107) for connecting the cold air valve (106); a front temperature measuring element (109) is provided at the front end of the heat exchanger (103) on the pipeline of the furnace tail exhaust pipe (101), and an induced draft fan temperature measuring element (111) is provided on the pipeline between the furnace pressure regulating valve (105) and the induced draft fan (107).

2. The system for regulating the furnace pressure of a heating furnace according to claim 1, characterized in that: A rear temperature measuring element (110) is provided on the rear exhaust pipe (104) at the rear end of the heat exchanger (103), and an induced draft fan pressure measuring element (112) is also provided on the pipeline between the furnace pressure regulating valve (105) and the induced draft fan (107); the outlet pipeline of the induced draft fan (107) is connected to a steel chimney (108).

3. The system for regulating the furnace pressure of a heating furnace according to claim 1, characterized in that: The outer periphery of the rear smoke exhaust duct (104) is wrapped with a heat-insulating environmentally friendly blanket.

4. A regulating valve for regulating the furnace pressure of a heating furnace, applied to a system for regulating the furnace pressure of a heating furnace according to any one of claims 1 to 3, characterized in that: The furnace pressure regulating valve (105) is a rotary plate valve without an insulating lining, which includes a steel pipe (7) and flanges at both ends thereof for connecting to pipelines. A support (3) is fixedly provided on the outside of the steel pipe (7). The support (3) is rotatably connected to a rotating shaft (1) perpendicular to the steel pipe (7). The rotating shaft (1) passes through the outer wall of the steel pipe (7) and is fixedly connected to a valve plate (2) inside the steel pipe (7). Semicircular ring blocks (8) are fixedly provided on the inner wall of the steel pipe (7) on both sides of the rotating shaft (1). The ring blocks (8) are perpendicular to the steel pipe (7), and the two ring blocks (8) are respectively located on both sides of the valve plate (2); the diameter of the valve plate (2) is smaller than the inner diameter of the steel pipe (7), and the sum of the width of the ring block (8) and the diameter of the valve plate (2) is greater than the inner diameter of the steel pipe (7).

5. The regulating valve for regulating the furnace pressure of a heating furnace according to claim 4, characterized in that: A plurality of ribs (9) are fixedly provided on both sides of the ring baffle (8) for reinforcement, and the ribs (9) are fixedly connected to the inner wall of the steel pipe (7).

6. The regulating valve for regulating the furnace pressure of a heating furnace according to claim 4, characterized in that: The inner diameter of the furnace pressure regulating valve (105) is smaller than the inner diameter of the rear smoke exhaust pipe (104).

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