A quick cooling method for overhauling a regenerative heating furnace
By shutting off the gas reversing valve and induced draft fan during the overhaul of the regenerative heating furnace, and using air backflow to cool the gas burners, the problem of excessively long cooling time was solved, achieving rapid cooling and efficient production, and creating significant economic benefits.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- YANGCHUN NEW STEEL CO LTD
- Filing Date
- 2023-07-03
- Publication Date
- 2026-05-29
Smart Images
Figure CN116951990B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a rapid cooling method for overhauling a regenerative heating furnace. Background Technology
[0002] With the fan and cooling water inside the furnace running continuously, a conventional walking beam furnace takes 72 hours to cool down from its normal production temperature to 100°C. A regenerative furnace requires even longer cooling time, typically exceeding 84 hours. This is because the gas supply to a regenerative furnace is stopped during cooling. To prevent the gas reversing valve from burning out, both the valve and the induced draft fan must be shut down. The heat storage medium of the gas burners remains at a high temperature for an extended period, unable to receive effective cooling. Cooling is only achieved passively through the air burners via the air induced draft fan. However, since gas burners account for half of all burners in the furnace, the temperature decreases slowly and takes a long time. In production, a regenerative furnace temperature can be reduced from 1150°C to approximately 350°C in just one day, but reducing it from 350°C to 100°C in the later stages takes two and a half days.
[0003] A regenerative thermal heater is a combination of a regenerative heat exchanger and a conventional heater. It mainly consists of the heater body, a regenerator chamber, a reversing system, and fuel, air supply, and exhaust systems. The piping for the fuel, air supply, and exhaust systems shares a single reversing valve to switch between these functions. Summary of the Invention
[0004] The purpose of this invention is to provide a rapid cooling method for overhauling a regenerative heating furnace.
[0005] A rapid cooling method for overhauling a regenerative heating furnace involves stopping the gas supply, closing the gas-side valve and flue gas-side valve of the gas reversing valve, and shutting down the gas induced draft fan when entering the cooling process. The air-side valve of the air reversing valve is then opened, and the air induced draft fan is started to send air into the furnace to cool it down to 350°C. Then, the gas induced draft fan damper on the gas supply pipeline is opened, and the flue gas-side valve of the gas reversing valve is opened. The air induced draft fan on the air supply pipeline draws cold outside air back through the gas chimney into the gas heating burner to cool its heat storage body.
[0006] Furthermore, after the temperature inside the furnace drops to 300°C, the gas induced draft fan is turned on to force cooling.
[0007] Compared with existing conventional furnace cooling methods, the rapid furnace cooling method provided by this invention has the advantages of rapid furnace temperature reduction without adversely affecting the construction of the heating furnace. Implemented during a major overhaul of a regenerative heating furnace, when the furnace temperature drops to between 300°C and 350°C, cold air is used for backflow cooling. When the furnace temperature drops to 300°C, the gas induced draft fan is started, and the reversing valve does not trigger an over-temperature alarm, successfully reducing the furnace cooling time to 48 hours.
[0008] Benefit Calculation: Reducing the furnace cooling time from 84 hours to 48 hours allows for an additional 36 hours of production. Based on an average hourly output of 150 tons / hour, a yield rate of 97%, and a profit of 100 yuan per ton of steel, the resulting benefit is: 36... 150 97% 100 = 523,800 yuan. Subtract the electricity cost of 250 kW for starting the gas exhaust fan. 24h 0.5 yuan / kWh = 3000 yuan, then the net benefit generated is 520,800 yuan. Attached Figure Description
[0009] Figure 1 This is a schematic diagram of the reversing unit structure of a regenerative heating furnace.
[0010] Figure 2 A schematic diagram of the structure of the heat storage body for a forced backflow cooling gas burner.
[0011] 1. Furnace, 11. First upper heating burner, 12. First lower heating burner, 2. Flue gas branch pipe, 21. Second upper heating burner, 22. Second lower heating burner, 3. First reversing valve, 4. Second reversing valve, 5. Gas (or air) branch pipe, 6. Gas chimney, 7. Air chimney, 8. Gas induced draft fan, 9. Air induced draft fan. Detailed Implementation
[0012] like Figure 1 As shown, the regenerative heating furnace has two burners on each side of the furnace chamber 1, each supplying the same type of gas (air or coal gas). The burners on the same side are designated as the upper heating burner and the lower heating burner. Both burners share a single reversing valve. The reversing valve for coal gas is called a coal gas reversing valve, and the reversing valve for air is called an air reversing valve. The coal gas reversing valve and the air reversing valve located on the same side form a reversing unit. Figure 1 In the figure, the first reversing valve 3 is a gas reversing valve, the second reversing valve 4 is an air reversing valve, the first upper heating burner 11 and the first lower heating burner 12 are gas burners, and the second upper heating burner 21 and the second lower heating burner 22 are air burners.
[0013] During operation, when the gas-side valve of the first reversing valve 3 is open and the flue gas-side valve is closed, the gas in the pipeline is fed into the furnace 1 for combustion through the first upper heating burner 11 and the first lower heating burner 12. At this time, the flue gas-side valve of the second reversing valve 4 is opened to exhaust smoke, while the air-side valve is closed. After the set reversing time is reached, the gas-side valve of the first reversing valve 3 closes, and then its flue gas-side valve opens to begin exhausting smoke; simultaneously, the flue gas-side valve of the second reversing valve 4 closes, and then its air-side valve opens, supplying air from the pipeline into the furnace for combustion through the second upper heating burner 21 and the second lower heating burner 22.
[0014] When cooling the furnace, the gas supply is stopped, and the gas-side valve and flue gas-side valve of the first reversing valve 3 are closed, so neither gas is supplied nor flue gas is discharged, and the gas induced draft fan 8 is shut down. The air-side valve of the second reversing valve 4 is opened, and the air induced draft fan 9 starts to send air into the furnace 1 to cool it down, reducing the furnace temperature to 350℃. Since both the gas-side valves of the first reversing valve 3 and the flue gas-side valves of the second reversing valve 4 are closed, neither gas is supplied nor flue gas is discharged, and the gas induced draft fan 8 is shut down, the heat storage body of the gas burner cannot be effectively cooled. Therefore, if... Figure 2 As shown, open the damper of the gas induced draft fan 8 and open the exhaust valve on the first reversing valve 3. The air induced draft fan 9 forces cold outside air back into the gas burner through the gas chimney 6 to cool its heat storage body. After the furnace temperature drops to 300℃, turn on the gas induced draft fan 8 to force cooling.
Claims
1. A rapid cooling method for overhauling a regenerative heating furnace, characterized in that, When entering the cooling process, stop supplying gas, close the gas-side valve and flue gas-side valve of the gas reversing valve, and shut down the gas induced draft fan; open the air-side valve of the air reversing valve, start the air induced draft fan to send air into the furnace to cool it down, reducing the furnace temperature to 350℃, then open the gas induced draft fan damper on the gas supply pipeline, and open the flue gas-side valve of the gas reversing valve, using the suction force of the air induced draft fan on the air supply pipeline to backflow cold air from the outside through the gas chimney into the gas heating burner to cool its heat storage body.
2. The rapid cooling method for overhauling a regenerative heating furnace according to claim 1, characterized in that, Once the temperature inside the furnace drops to 300℃, turn on the gas induced draft fan to force cooling.