Organic heat carrier furnace

Abstract

The invention relates to an organic heat carrier furnace which adopts a liquid-phase organic heat carrier internal circulation heat regeneration technology combining an economizer and an external air pre-heater to recover flue gas waste heat, so that flue gas low-temperature corrosion is effectively avoided, and meanwhile, efficient recovery and utilization of the flue gas waste heat are realized. And the worldwide problems of low heat efficiency, low-temperature corrosion and difficulty in waste heat recovery of the organic heat carrier furnace are solved, and the system can replace a steam boiler to supply heat, is particularly suitable for water-deficient areas, and has excellent economic and social significance in implementation and popularization.

Description

Technical Field

[0001] The invention belongs to the technical field of boilers, and in particular relates to an organic heat carrier boiler adopting economizer and external air preheater heat recovery technology. Background Art

[0002] A thermal oil boiler (i.e., organic heat carrier boiler) is a special boiler that uses an organic heat carrier, i.e., thermal oil, as its working medium. The high-temperature flue gas generated by the combustion of fuel heats the thermal oil. After the temperature of the thermal oil is increased, it provides the required heat for the heat-using equipment. When the flue gas generated by the combustion of the fuel is discharged through the chimney, the temperature is generally around 250°C, and some are even as high as 350°C, which not only wastes heat but also causes thermal pollution to the environment.

[0003] The thermal oil furnace uses an air preheater to recover part of the flue gas waste heat, but there is a problem of low-temperature corrosion of the air preheater. Some processes are equipped with waste heat recovery devices with steam generators such as heat pipe boilers. For example, ZL200420027889.4 provides a waste heat recovery device for the tail gas of a thermal oil furnace with a steam generator. This technology can reduce the exhaust temperature of the thermal oil furnace to about 160°C and recover a certain amount of steam; however, if the thermal oil furnace user does not need the steam generated by the waste heat recovery process, or the steam load changes, the common phenomenon of excess steam venting of the steam generator will occur. The use of this type of technology is greatly restricted, and the overall thermal efficiency of the organic heat carrier furnace is still low, which does not meet the requirements of energy saving and environmental protection.

[0004] Therefore, how to reasonably recycle and utilize the flue gas waste heat of the organic heat carrier furnace, reduce the exhaust temperature, avoid low-temperature corrosion, and improve the overall thermal efficiency of the organic heat carrier furnace has become a hot topic in this field. Summary of the invention

[0005] The purpose of the present invention is to solve the shortcomings of the above-mentioned prior art. The economizer and the air preheater outside the furnace are used for heat recovery to achieve efficient recovery of waste heat from the flue gas of the organic heat carrier furnace, while effectively avoiding low-temperature corrosion of the flue gas to the economizer, thereby achieving the purpose of energy saving and consumption reduction.

[0006] The purpose of the present invention is achieved by the following measures:

[0007] An organic heat carrier furnace, characterized in that the organic heat carrier furnace comprises a high-temperature side heat transfer oil furnace and a heat recovery unit.

[0008] The high-temperature side thermal oil furnace comprises a thermal oil furnace body 1, a burner 2, a thermal oil pump 7, a heat-using device 3, an oil-gas separator 5, a filter 6 and a connecting pipeline. The thermal oil is sequentially passed through the thermal oil pump 7, the thermal oil furnace body 1, the heat-using device 3, the oil-gas separator 5, the filter 6 connected by the pipeline, and then returns to the thermal oil pump 7. The high-temperature side thermal oil furnace is provided with a high-position expansion tank 4 and a low-position oil storage tank 8. The oil-gas separator 5 is connected to the high-position expansion tank 4 through an expansion pipe, and the high-position expansion tank 4 is connected to the low-position oil storage tank 8 through an overflow pipe.

[0009] The heat recovery unit includes an air preheater 12 outside the furnace and an economizer 15.

[0010] The economizer 15 is arranged on the flue 9 of the high-temperature side thermal oil furnace. The flue gas with higher temperature in the flue 9 is discharged after the temperature is reduced by the economizer 15. The thermal oil drawn from the outlet of the thermal oil pump 7 and the heat-using equipment 3 is cooled by the air preheater 12 outside the furnace, and then enters the economizer 15 to recover the heat of the flue gas. The thermal oil with increased temperature coming out of the economizer 15 returns to the inlet pipeline of the thermal oil pump 7, and is transported to the burner 2 of the high-temperature side thermal oil furnace as combustion-supporting air through the blower 10 and the air preheater 12 outside the furnace.

[0011] The burner 2 of the high-temperature side thermal oil furnace uses coal, biomass, oil or gas as fuel.

[0012] The external air preheater 12 adopts an indirect heat exchange method, and the heat exchange tubes adopt smooth tubes, fin tubes or spiral groove tubes.

[0013] The economizer 15 adopts an indirect heat exchange method, and the heat exchange tubes adopt smooth tubes, finned tubes or spiral grooved tubes.

[0014] The economizer 15 is a serpentine heat exchanger, a shell and tube heat exchanger or other types of heat exchangers.

[0015] Preferably, the internal circulation heat transfer oil pipeline 11 is connected from the pipeline between the outlet of the heat transfer oil pump 7 and the heat transfer oil furnace body 1, enters the air preheater 12 outside the furnace, and heats the air sent into the air preheater 12 outside the furnace from the blower 10.

[0016] Preferably, the heat transfer oil with increased temperature coming out of the economizer 15 enters the oil-gas separator 5 through the heat transfer oil heat recovery pipeline 16 .

[0017] By controlling the inlet temperature of the heat transfer oil of the economizer 15 (for example, above 85°C, the appropriate temperature is determined according to the sulfur content of the fuel), low-temperature corrosion of the economizer 15 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 heat transfer oil furnace can operate economically and with high thermal efficiency, thereby achieving the purpose of energy saving and consumption reduction.

[0018] The heat recovery unit in the present invention is also applicable to an organic heat carrier furnace adopting suction circulation.

[0019] The undescribed facilities in the organic heat carrier furnace are matched with reference to or in accordance with the reliable and mature technologies in the known organic heat carrier furnace.

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

[0021] 1. It truly realizes the efficient heat utilization of the internal circulation of flue gas waste heat of the organic heat carrier furnace, which corresponds to the economizer technology (feedwater heat recovery type) in steam boilers and hot water boilers. It is the first time to propose the liquid phase organic heat carrier heat recovery technology that combines the "economizer" in the organic heat carrier furnace type with the air preheater outside the furnace, eliminating the shortcomings of the large volume and poor heat exchange effect of the hollow preheater in the organic heat carrier furnace type during heat recovery, and technically solves the global problem of low thermal efficiency of organic heat carrier furnaces;

[0022] 2. The heating range is above 180℃, which can truly replace steam boiler heating. It has no scaling, condensate recovery problems, no water treatment equipment, simple operation and maintenance, and is particularly suitable for water-scarce areas;

[0023] 3. Solve the acid dew point corrosion problem of tail flue air preheater, hot water type or steam type waste heat recovery equipment from the mechanism point of view;

[0024] 4. Stable operation - Eliminate heat waste caused by load changes at the hot water or steam user end of hot water or steam type equipment in the tail flue (such as steam venting, etc.), and make operation adjustment flexible and convenient;

[0025] 5. Easy and compact installation - compared with the air preheater in the flue, the economizer in the tail flue is small in size and has a large heat transfer coefficient, and the air preheater outside the furnace is compact and convenient to arrange. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of an organic heat carrier furnace of the present invention.

[0027] Figure 1 Among them, 1-thermal oil furnace body, 2-burner, 3-heat-using equipment, 4-high-level expansion tank, 5-oil-gas separator, 6-filter, 7-thermal oil pump, 8-low-level oil storage tank, 9-flue, 10-blower, 11-internal circulation thermal oil pipeline, 12-outside air preheater, 13-cold oil pipeline, 14-hot air, 15-economizer, 16-thermal oil heat return pipeline. DETAILED DESCRIPTION

[0028] The following is combined with Figure 1 The present invention is further described in detail with reference to the accompanying drawings and specific examples.

[0029] Embodiment 1:

[0030] An organic heat carrier furnace, comprising a high-temperature side heat transfer oil furnace and a heat recovery unit.

[0031] The high-temperature side thermal oil furnace comprises a thermal oil furnace body 1, a burner 2, a thermal oil pump 7, a heat-using device 3, an oil-gas separator 5, a filter 6 and a connecting pipeline. The thermal oil is sequentially passed through the thermal oil pump 7, the thermal oil furnace body 1, the heat-using device 3, the oil-gas separator 5, the filter 6 connected by the pipeline, and then returns to the thermal oil pump 7. The high-temperature side thermal oil furnace is provided with a high-position expansion tank 4 and a low-position oil storage tank 8. The oil-gas separator 5 is connected to the high-position expansion tank 4 through an expansion pipe, and the high-position expansion tank 4 is connected to the low-position oil storage tank 8 through an overflow pipe.

[0032] The heat recovery unit includes an air preheater 12 outside the furnace and an economizer 15.

[0033] The economizer 15 is arranged on the flue 9 of the high-temperature side thermal oil furnace. The flue gas with higher temperature in the flue 9 is discharged after the temperature is reduced by the economizer 15. The heat transfer oil drawn from the outlet of the thermal oil furnace body 1 and the heat-using equipment 3 is cooled by the internal circulation heat transfer oil pipeline 11 and the air preheater 12 outside the furnace, and then enters the economizer 15 to recover the heat of the flue gas. The heat transfer oil with increased temperature coming out of the economizer 15 enters the oil-gas separator 5 through the heat transfer oil heat recovery pipeline 16, and is transported to the burner 2 of the high-temperature side thermal oil furnace as combustion-supporting air by the blower 10 and the hot air 14 formed by the air preheater 12 outside the furnace.

[0034] The burner 2 of the high-temperature side thermal oil furnace uses coal, biomass, oil or gas as fuel.

[0035] The external air preheater 12 adopts an indirect heat exchange method, and the heat exchange tubes adopt smooth tubes, fin tubes or spiral groove tubes.

[0036] The economizer 15 adopts an indirect heat exchange method, and the heat exchange tubes adopt smooth tubes, finned tubes or spiral grooved tubes.

[0037] The economizer 15 is a serpentine heat exchanger, a shell and tube heat exchanger or other types of heat exchangers.

[0038] Preferably, the internal circulation heat transfer oil pipeline 11 is connected from the pipeline between the outlet of the heat transfer oil pump 7 and the heat transfer oil furnace body 1, enters the air preheater 12 outside the furnace, and heats the air sent into the air preheater 12 outside the furnace from the blower 10.

[0039] Preferably, the heat transfer oil with increased temperature coming out of the economizer 15 enters the oil-gas separator 5 through the heat transfer oil heat recovery pipeline 16 .

[0040] By controlling the inlet temperature of the heat transfer oil of the economizer 15 (for example, above 85°C, the appropriate temperature is determined according to the sulfur content of the fuel), low-temperature corrosion of the economizer 15 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 heat transfer oil furnace can operate economically and with high thermal efficiency, thereby achieving the purpose of energy saving and consumption reduction.

[0041] The heat recovery unit in the present invention is also applicable to an organic heat carrier furnace adopting suction circulation.

[0042] The undescribed facilities in the organic heat carrier furnace are matched with reference to or in accordance with the reliable and mature technologies in the known organic heat carrier furnace.

[0043] 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 organic heat carrier furnace, characterized in that: The organic heat carrier furnace includes a high-temperature side heat transfer oil furnace and a heat recovery unit. The high-temperature side thermal oil furnace comprises a thermal oil furnace body (1), a burner (2), a thermal oil pump (7), a heat-using device (3), an oil-gas separator (5) and connecting pipelines. The thermal oil is sequentially connected to the thermal oil pump (7), the thermal oil furnace body (1), the heat-using device (3), the oil-gas separator (5) through the pipelines, and then returns to the thermal oil pump (7). The high-temperature side thermal oil furnace is provided with a high-position expansion tank (4) and a low-position oil storage tank (8). The oil-gas separator (5) is connected to the high-position expansion tank (4) through an expansion pipe, and the high-position expansion tank (4) is connected to the low-position oil storage tank (8) through an overflow pipe. The heat recovery unit comprises an air preheater (12) outside the furnace and an economizer (15). The economizer (15) is arranged on the flue (9) of the high-temperature side thermal oil furnace. The flue gas with a relatively high temperature in the flue (9) is discharged after its temperature is reduced by the economizer (15). The thermal oil drawn from between the outlet of the thermal oil pump (7) and the heat-using equipment (3) is cooled by the air preheater (12) outside the furnace and then enters the economizer (15) to recover the heat of the flue gas. The thermal oil with a higher temperature coming out of the economizer (15) returns to the inlet pipeline of the thermal oil pump (7) and is transported to the burner (2) of the high-temperature side thermal oil furnace as combustion-supporting air by forming hot air (14) through the blower (10) and the air preheater (12) outside the furnace.

2. The organic heat carrier furnace according to claim 1, characterized in that: The burner (2) of the high-temperature side thermal oil furnace uses coal, biomass, oil or gas as fuel.

3. The organic heat carrier furnace according to claim 1, characterized in that: The external air preheater (12) adopts an indirect heat exchange method.

4. The organic heat carrier furnace according to claim 3, characterized in that: The heat exchange tubes of the external air preheater (12) are made of smooth tubes, finned tubes or spiral grooved tubes.

5. The organic heat carrier furnace according to claim 1, characterized in that: The economizer (15) adopts an indirect heat exchange method.

6. The organic heat carrier furnace according to claim 5, characterized in that: The heat exchange tubes of the economizer (15) are made of smooth tubes, finned tubes or spirally grooved tubes.

7. The organic heat carrier furnace according to claim 1, characterized in that: The heat recovery unit is also suitable for an organic heat carrier furnace adopting a suction circulation.

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