Flue gas waste heat recovery device for industrial furnace

Abstract

According to the flue gas waste heat recovery device for the industrial furnace, flue gas waste heat is recovered through a heat conduction oil internal circulation heat utilization technology combining a heat regenerator and an external air pre-heater, flue gas low-temperature corrosion is effectively avoided, meanwhile, efficient recovery and utilization of the flue gas waste heat of the industrial furnace are achieved, and implementation and popularization of the flue gas waste heat recovery device for the industrial furnace have extremely good economic and social significance.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial furnace fume waste heat recovery, and in particular relates to an industrial furnace fume waste heat recovery device using a regenerator and an external air preheater heat recovery technology. Background Art

[0002] Industrial furnaces use coal, oil, natural gas, etc. as fuel. Since the fuel contains sulfur, sulfur oxides will be produced during combustion. Sulfur oxides combine with water vapor to form sulfurous acid or sulfuric acid vapor. If the metal wall temperature of the heating surface of the waste heat recovery device (especially the air preheater) arranged at the tail of the industrial furnace is lower than the condensation point (acid dew point) of sulfuric acid vapor, liquid sulfuric acid (called acid dew) will form on its surface. As the heating surface at the tail of the waste heat recovery device, the air preheater often suffers from acid dew corrosion and ash blockage caused by too low wall temperature, which has not been effectively solved. Therefore, various waste heat recovery device designs in the world usually sacrifice waste heat recovery efficiency and alleviate (rather than eliminate) acid dew corrosion by increasing the exhaust temperature. However, increasing the exhaust temperature is bound to cause a large amount of low-temperature heat source waste. Air preheaters often experience acid dew corrosion after one to two years of operation, and even perforation and scrapping. This is a global problem that plagues waste heat recovery in industrial furnaces.

[0003] Therefore, how to reasonably recycle and utilize the waste heat from industrial furnace flue gas, reduce the exhaust temperature while effectively avoiding low-temperature corrosion, and achieve efficient utilization of the waste heat from industrial furnace flue gas has become a hot topic in this field. Summary of the invention

[0004] The purpose of the present invention is to solve the shortcomings of the above-mentioned existing air preheater technology, adopt the regenerator and the heat recovery technology of the air preheater outside the furnace, effectively avoid the low-temperature corrosion of the flue gas on the regenerator, and realize the efficient recovery and utilization of the waste heat of the flue gas of the industrial furnace.

[0005] The purpose of the present invention is achieved by the following measures:

[0006] An industrial furnace fume waste heat recovery device, characterized in that the industrial furnace fume waste heat recovery device comprises a thermal oil pump 8, a thermal oil heater 3, an oil-gas separator 10, a high-level oil tank 15, a regenerator 5, an external air preheater 12 and connecting pipelines thereof,

[0007] The heat transfer oil separated by the oil-gas separator 10 is pressurized by the heat transfer oil pump 8, and the pressurized heat transfer oil enters the heat transfer oil heater 3 for heating, and then supplies heat to the heat unit 9, and then returns to the oil-gas separator 10. The gas-liquid mixture generated by the oil-gas separator 10 enters the high-level oil tank 15 through the expansion pipe, and the high-temperature flue gas 2 generated by the industrial furnace 1 is cooled by the heat transfer oil heater 3 and the regenerator 5, and the low-temperature flue gas 6 formed is discharged. The heat transfer oil drawn out from the outlet of the heat transfer oil pump 8 and the oil-gas separator 10 enters the air preheater 12 outside the furnace for cooling through the internal circulation heat transfer oil pipeline 11, and then enters the regenerator 5 to recover the heat of the flue gas. The heat transfer oil with increased temperature coming out of the regenerator 5 returns to the inlet pipeline of the heat transfer oil pump 8, and is transported to the industrial furnace 1 as combustion-supporting air by the blower 19 and the hot air 17 formed by the air preheater 12 outside the furnace.

[0008] The fuel of the industrial furnace 1 is coal, biomass, oil or gas.

[0009] The industrial furnaces include smelting furnaces, melting furnaces, heating furnaces, heat treatment furnaces, calcining furnaces, rotary kilns, organic matter incinerators, etc.

[0010] The heat transfer oil and air of the external air preheater 12 adopt an indirect heat exchange method, and the heat exchange tubes adopt smooth tubes, fin tubes or spiral groove tubes.

[0011] The heat transfer oil and flue gas of the heat transfer oil heater 3 adopt an indirect heat exchange method, and the heat exchange tube adopts a plain tube, a fin tube or a spiral groove tube.

[0012] The heat transfer oil and flue gas of the regenerator 5 adopt an indirect heat exchange method, and the heat exchange tubes adopt smooth tubes, fin tubes or spiral grooved tubes.

[0013] A filter 7 is provided: the heat transfer oil coming out of the oil-gas separator 10 enters the heat transfer oil pump 8 through the filter 7, and the filter 7 is used to filter out solid impurity particles in the imported heat transfer oil.

[0014] Preferably, the internal circulation heat transfer oil pipeline 11 is connected from the pipeline between the outlet of the heat transfer oil pump 8 and the heat transfer oil heater 3, and is transported to the air preheater 12 outside the furnace to heat the cold air 16 sent into the air preheater 12 outside the furnace from the blower 19.

[0015] By controlling the inlet temperature of the heat transfer oil of the regenerator 5 (for example, above 85°C, the appropriate temperature is determined according to the sulfur content of the fuel), low-temperature corrosion of the regenerator 5 can be effectively avoided. Under the premise of avoiding condensation, the waste heat of the flue gas can be utilized to the maximum extent, so that the flue gas waste heat recovery device can operate economically and with high thermal efficiency, thereby achieving the purpose of energy saving and consumption reduction.

[0016] The oil-gas separator 10 and the high-position oil tank 15 may adopt an integrated structure, and the high-position oil tank 15 also serves as the oil-gas separator.

[0017] Preferably, the high-position oil tank 15 is provided with a safety valve, an exhaust valve, and a discharge valve, and is sealed and protected by nitrogen.

[0018] A low-position oil tank 18 is provided: the low-position oil tank 18 is connected to the high-position oil tank 15 through an overflow pipe, and the low-position oil tank 18 is used to store the heat transfer oil of the flue gas waste heat recovery device system.

[0019] Parts not mentioned in the present invention may be implemented using existing technologies, that is, existing mature and reliable reasonable improvement measures may be introduced into the present system, such as setting necessary valves, bypasses, automatic control facilities, etc.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. Energy saving: Using heat transfer oil as heat carrier, combined with heat recovery technology of heat regenerator and air preheater outside the furnace, it can effectively avoid low-temperature corrosion of industrial furnace flue gas and realize efficient recovery and utilization of flue gas waste heat;

[0022] 2. Easy and compact installation: The air preheater and regenerator outside the furnace are easy to install, which can effectively save and utilize the equipment;

[0023] 3. Flexible and convenient operation adjustment: Under the premise of ensuring the heating of the heating unit, the adjustment is flexible and convenient to effectively reduce the exhaust temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a schematic structural diagram of an industrial furnace fume waste heat recovery device.

[0025] Figure 1 Among them, 1-industrial kiln, 2-high temperature flue gas, 3-thermal oil heater, 4-heater outlet flue gas, 5-regenerator, 6-low temperature flue gas, 7-filter, 8-thermal oil pump, 9-heat unit, 10-oil-gas separator, 11-internal circulation thermal oil pipeline, 12-outside air preheater, 13-cold oil pipeline, 14-return oil pipeline, 15-high-level oil tank, 16-cold air, 17-hot air, 18-low-level oil tank, 19-blower. DETAILED DESCRIPTION

[0026] The following is combined with Figure 1 The present invention is further described in detail with reference to the accompanying drawings and specific examples.

[0027] Embodiment 1:

[0028] An industrial furnace fume waste heat recovery device, the industrial furnace fume waste heat recovery device comprising a thermal oil pump 8, a thermal oil heater 3, an oil-gas separator 10, a high-position oil tank 15, a regenerator 5, an external air preheater 12 and connecting pipelines thereof,

[0029] The heat transfer oil separated by the oil-gas separator 10 is pressurized by the heat transfer oil pump 8, and the pressurized heat transfer oil enters the heat transfer oil heater 3 for heating, and then supplies heat to the heat using unit 9, and then returns to the oil-gas separator 10. The gas-liquid mixture generated by the oil-gas separator 10 enters the high-level oil tank 15 through the expansion pipe, and the high-level oil tank 15 is connected to the low-level oil tank 18 through the overflow pipe. The high-temperature flue gas 2 generated by the industrial furnace 1 is cooled by the heat transfer oil heater 3, and the flue gas 4 formed at the outlet of the heat transfer oil heater enters the regenerator 5, the low-temperature flue gas 6 formed after cooling is discharged, the heat transfer oil drawn from the heat transfer oil heater 3 and the heat using unit 9 enters the air preheater 12 outside the furnace through the internal circulation heat transfer oil pipeline 11 for cooling, and the low-temperature heat transfer oil formed enters the regenerator 5 through the cold oil pipeline 13 to recover the heat of the flue gas, the heat transfer oil with increased temperature coming out of the regenerator 5 returns to the oil-gas separator 10 through the return oil pipeline 14, and is transported to the industrial furnace 1 as combustion air by the blower 19 and the hot air 17 formed by the air preheater 12 outside the furnace.

[0030] The fuel of the industrial furnace 1 is biomass fuel.

[0031] The industrial furnaces include smelting furnaces, melting furnaces, heating furnaces, heat treatment furnaces, calcining furnaces, rotary kilns, organic matter incinerators, etc.

[0032] The heat transfer oil and air of the external air preheater 12 adopt an indirect heat exchange method, and the heat exchange tubes adopt smooth tubes, fin tubes or spiral groove tubes.

[0033] The heat transfer oil and flue gas of the heat transfer oil heater 3 adopt an indirect heat exchange method, and the heat exchange tube adopts a plain tube, a fin tube or a spiral groove tube.

[0034] The heat transfer oil and flue gas of the regenerator 5 adopt an indirect heat exchange method, and the heat exchange tubes adopt smooth tubes, fin tubes or spiral grooved tubes.

[0035] A filter 7 is provided: the heat transfer oil coming out of the oil-gas separator 10 enters the heat transfer oil pump 8 through the filter 7, and the filter 7 is used to filter out solid impurity particles in the imported heat transfer oil.

[0036] Preferably, the internal circulation heat transfer oil pipeline 11 is connected from the pipeline between the outlet of the heat transfer oil pump 8 and the heat transfer oil heater 3, and is transported to the air preheater 12 outside the furnace to heat the cold air 16 sent into the air preheater 12 outside the furnace from the blower 19.

[0037] By controlling the inlet temperature of the heat transfer oil of the regenerator 5 (for example, above 85°C, the appropriate temperature is determined according to the sulfur content of the fuel), low-temperature corrosion of the regenerator 5 can be effectively avoided. Under the premise of avoiding condensation, the waste heat of the flue gas can be utilized to the maximum extent, so that the flue gas waste heat recovery device can operate economically and with high thermal efficiency, thereby achieving the purpose of energy saving and consumption reduction.

[0038] The oil-gas separator 10 and the high-position oil tank 15 may adopt an integrated structure, and the high-position oil tank 15 also serves as the oil-gas separator.

[0039] Preferably, the high-position oil tank 15 is provided with a safety valve, an exhaust valve, and a discharge valve, and is sealed and protected by nitrogen.

[0040] A low-position oil tank 18 is provided: the low-position oil tank 18 is connected to the high-position oil tank 15 through an overflow pipe, and the low-position oil tank 18 is used to store the heat transfer oil of the flue gas waste heat recovery device system.

[0041] Parts not mentioned in the present invention may be implemented using existing technologies, that is, existing mature and reliable reasonable improvement measures may be introduced into the present system, such as setting necessary valves, bypasses, automatic control facilities, etc.

[0042] Although the present invention has been disclosed as above with preferred embodiments, they are not intended to limit the present invention. Anyone familiar with the art can make various changes or modifications without departing from the spirit and scope of the present invention, which also belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the definition of the claims of this application.

Claims

1. An industrial furnace flue gas waste heat recovery device, characterized in that: The industrial furnace flue gas waste heat recovery device comprises a heat transfer oil pump (8), a heat transfer oil heater (3), an oil-gas separator (10), a high-position oil tank (15), a heat regenerator (5), an external air preheater (12), and connecting pipelines.

2. The industrial furnace flue gas waste heat recovery device according to claim 1 is characterized in that: The heat transfer oil separated by the oil-gas separator (10) is pressurized by a heat transfer oil pump (8), and the pressurized heat transfer oil enters the heat transfer oil heater (3) to be heated and heated, and then supplies heat to the heat-using unit (9), and then returns to the oil-gas separator (10). The gas-liquid mixture generated by the oil-gas separator (10) enters the high-position oil tank (15) through the expansion pipe. The high-temperature flue gas (2) generated by the industrial furnace (1) is cooled by the heat transfer oil heater (3) and the regenerator (5), and the low-temperature flue gas is formed. (6) The heat transfer oil drawn from the outlet of the heat transfer oil pump (8) and the oil-gas separator (10) enters the external air preheater (12) through the internal circulation heat transfer oil pipeline (11) to cool down, and then enters the regenerator (5) to recover the flue gas heat. The heat transfer oil with increased temperature coming out of the regenerator (5) returns to the inlet pipeline of the heat transfer oil pump (8), and is transported to the industrial furnace (1) as combustion air through the blower (19) and the hot air (17) formed by the external air preheater (12).

3. The industrial furnace flue gas waste heat recovery device according to claim 1 is characterized in that: The industrial furnaces include smelting furnaces, melting furnaces, heating furnaces, heat treatment furnaces, calcining furnaces, rotary kilns, and organic matter incinerators.

4. The industrial furnace flue gas waste heat recovery device according to claim 2 is characterized in that: The fuel of the industrial furnace (1) is coal, biomass, oil or gas.

5. The industrial furnace flue gas waste heat recovery device according to claim 1 is characterized in that: The heat transfer oil and air of the external air preheater (12) adopt an indirect heat exchange method, and the heat exchange tubes adopt smooth tubes, fin tubes or spiral groove tubes.

6. The industrial furnace flue gas waste heat recovery device according to claim 1 is characterized in that: The heat transfer oil and flue gas of the heat transfer oil heater (3) adopt an indirect heat exchange method, and the heat exchange tube adopts a plain tube, a fin tube or a spiral groove tube.

7. The industrial furnace flue gas waste heat recovery device according to claim 1 is characterized in that: The heat transfer oil and flue gas of the regenerator (5) adopt an indirect heat exchange method, and the heat exchange tubes adopt smooth tubes, finned tubes or spiral grooved tubes.

8. The industrial furnace fume waste heat recovery device according to claim 1 is characterized in that: The oil-gas separator (10) and the high-position oil tank (15) adopt an integrated structure and play the role of oil-gas separation.

9. The industrial furnace flue gas waste heat recovery device according to claim 1, characterized in that: A low-level oil tank (18) is provided: the low-level oil tank (18) is connected to the high-level oil tank (15) via an overflow pipe, and the low-level oil tank (18) is used to store heat transfer oil of the flue gas waste heat recovery device system.

10. The household micro thermal oil furnace system according to claim 1, characterized in that: A filter (7) is provided: the heat transfer oil coming out of the oil-gas separator (10) enters the heat transfer oil pump (8) through the filter (7).

Images