Organic waste gas treatment and waste heat recovery system

Abstract

The utility model provides an organic waste gas treatment and waste heat recovery system in the technical field of waste heat recovery. The system comprises a VOCs incinerator (1), a waste heat steam generator (2), an air preheater (3), a water preheater (4) and an induced draft fan (7), wherein the waste heat steam generator (2), the air preheater (3), the water preheater (4) and the induced draft fan (7) are sequentially communicated with a waste gas outlet of the VOCs incinerator (1); a cold water inlet and a hot water outlet are formed in the water pre-heater, the hot water outlet of the water pre-heater is communicated to a water inlet of the waste heat steam generator, and high-temperature steam is discharged from a steam outlet of the waste heat steam generator; an air inlet of the air pre-heater is connected with a combustion fan, and an air outlet of the air pre-heater is communicated to an air inlet of the VOCs incinerator; the combustion fan is further connected with an air inlet of an incandescent light of the VOCs incinerator. According to the waste heat recovery system, waste heat in waste gas is effectively recovered through three-stage heat exchange in a specific sequence and is used for generating energy in other forms, the utilization efficiency of waste heat energy in the waste gas is improved to the maximum extent, energy waste and environmental pollution are reduced, and the system has wide application prospects.

Description

Technical Field

[0001] The utility model relates to the technical field of organic waste gas treatment and waste heat recovery, and in particular to an organic waste gas treatment and waste heat recovery system. Background Art

[0002] In China, volatile organic compounds, VOCs (volatile organic compounds), refer to organic compounds with a saturated vapor pressure greater than 70P at room temperature and a boiling point below 260°C at normal pressure, or all organic compounds with corresponding volatility and a vapor pressure greater than or equal to 10Pa at 20°C. At present, the emission control and treatment of VOCs have become an important issue in the field of environmental protection. When the concentration of VOCs in the exhaust gas is low (500-5000mg / m³), the exhaust gas itself is not enough as a fuel, and auxiliary fuel needs to be added as a combustion-supporting gas. In the process of auxiliary fuel combustion, the combustible components in the exhaust gas are destroyed, and the temperature after combustion is usually maintained at around 850°C. In view of the large amount of heat energy contained in the high-temperature exhaust gas generated by the VOCs incinerator during the treatment process, it is particularly important to develop a system that can effectively treat the exhaust gas and efficiently recover the waste heat.

[0003] At present, the organic waste gas treatment and waste heat recovery system mainly includes three main parts: high-efficiency incineration unit, heat recovery unit and control system.

[0004] Patent CN203571765U discloses a harmless incineration-heat medium treatment system for organic waste gas and waste liquid. The incineration system includes an incinerator, a thermal oil heat exchanger, an air preheater, a combustion-supporting fan and an induced draft fan; the heat medium system includes a thermal oil air cooler, a thermal oil circulation pump, a thermal oil heat exchanger and a heat medium furnace; the thermal oil passes through the thermal oil air cooler, the thermal oil circulation pump, the thermal oil heat exchanger and the heat medium furnace in sequence, and the waste is sent to the incinerator to generate high-temperature flue gas, which is then exchanged with the thermal oil and discharged into the atmosphere; at the same time, the combustion-supporting air is introduced into the incinerator to assist combustion. The incinerator realizes the harmless treatment of waste liquid and waste gas, the thermal oil heat exchanger recovers the heat energy in the high-temperature flue gas, and the air preheater further recovers the waste heat of the high-temperature flue gas. This method only uses two-stage heat exchange recovery, and the waste heat recovery efficiency is not high enough. Utility Model Content

[0005] The utility model provides an organic waste gas treatment and waste heat recovery system to solve the problem that the existing organic waste gas has low waste heat recovery efficiency after combustion treatment.

[0006] The technical solution of the utility model is:

[0007] The organic waste gas treatment and waste heat recovery system includes a VOCs incinerator 1, which is characterized in that it also includes a waste heat steam generator 2, an air preheater 3, a water preheater 4 and an induced draft fan 7 which are sequentially connected to the waste gas outlet of the VOCs incinerator 1; a cold water inlet and a hot water outlet are arranged on the water preheater, the hot water outlet of the water preheater 4 is connected to the water inlet of the waste heat steam generator 2, and the steam outlet of the waste heat steam generator 2 discharges high-temperature steam; the air inlet of the air preheater 3 is connected to the combustion-supporting fan 6, and the air outlet of the air preheater is connected to the air inlet 17 of the VOCs incinerator; the combustion-supporting fan 6 is also connected to the air inlet of the ever-burning lamp of the VOCs incinerator 1.

[0008] Preferably, the air inlet 17, the exhaust gas inlet 16 and the natural gas inlet of the VOCs incinerator are separately arranged.

[0009] Preferably, the air outlet of the air preheater is connected to the VOCs incinerator 1 in two ways, one way is connected to the side of the VOCs incinerator 1, and the other way is connected to the end face of the VOCs incinerator 1.

[0010] Preferably, the air outlet of the air preheater is connected to the end surface of the VOCs incinerator 1 through the annular uniform air duct 15. The annular uniform air duct can be circular or square.

[0011] Preferably, a first pressure transmitter 11 is arranged in the furnace of the VOCs incinerator 1, and the first pressure transmitter 11 is electrically connected to the frequency converter of the induced draft fan 7 through a PLC controller to control the rotation speed of the induced draft fan.

[0012] Preferably, a second pressure transmitter 12 is provided in the pipeline between the air preheater outlet and the VOCs incinerator 1 , and the second pressure transmitter 12 is electrically connected to the combustion-supporting fan 6 via a PLC controller.

[0013] Preferably, a temperature sensor 10 is arranged in the furnace of the VOCs incinerator 1 and / or on the pipeline between the air preheater outlet and the VOCs incinerator 1 and / or on the connecting pipeline between the waste heat steam generator 2 and the air preheater 3 and / or at the outlet of the induced draft fan.

[0014] Preferably, the water preheater 4 is connected to the water tank 5 , the water tank 5 replenishes cold water to the water preheater 4 , and the hot water discharged from the water preheater 4 is transported to the water inlet of the waste heat steam generator 2 through the water tank.

[0015] Preferably, the steam outlet of the waste heat steam generator 2 is connected to the gas-liquid separator 9, the liquid outlet of the gas-liquid separator 9 is connected to the water inlet of the waste heat steam generator 2, the liquid outlet of the gas-liquid separator 9 is also connected to the water tank, and the gas outlet of the gas-liquid separator 9 discharges steam.

[0016] Preferably, the water in the water tank is also connected to the induced draft fan 7 for cooling the induced draft fan 7 .

[0017] The advantages of the utility model are: the utility model provides an organic waste gas treatment and waste heat recovery system, which, through three-stage heat exchange in a specific order, effectively recovers the waste heat in the waste gas and uses it to generate other forms of energy, thereby maximizing the waste heat energy utilization efficiency in the waste gas. At the same time, it improves the waste gas treatment combustion efficiency, reduces fuel consumption, reduces energy waste and environmental pollution, and the system has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the control principle of the utility model;

[0019] Figure 2 This is a schematic diagram of the structure of the annular uniform air duct of the utility model.

[0020] Among them: 1. VOCs incinerator; 2. Waste heat steam generator; 3. Air preheater; 4. Water preheater; 5. Water tank; 6. Combustion-supporting fan; 7. Induced draft fan; 8. Chimney; 9. Gas-liquid separator; 10. Temperature sensor; 11. First pressure transmitter; 12. Second pressure transmitter; 13. Co-burner; 14. Water make-up pump; 15. Annular uniform air duct; 16. Waste gas inlet; 17. Air inlet of VOCs incinerator. DETAILED DESCRIPTION

[0021] like Figure 1 As shown, the organic waste gas treatment and waste heat recovery system includes a VOCs incinerator 1 and a waste heat recovery device, which is installed at the rear end of the waste gas emission of the VOCs incinerator to recover the waste heat in the waste gas after high-temperature combustion. Specifically, the waste heat recovery device includes a waste heat steam generator 2, an air preheater 3, a water preheater 4 and an induced draft fan 7, which are sequentially connected to the waste gas outlet of the VOCs incinerator 1.

[0022] VOCs incinerator 1: used to incinerate industrial waste gas VOCs, the temperature can reach above 850℃, completely destroying the harmful components VOCs in the waste gas, and generating high-temperature waste gas after treatment, which contains a large amount of waste heat.

[0023] Waste heat steam generator 2: transfers the heat energy in the exhaust gas to the liquid medium water to generate steam for production and life use. Waste heat steam generator 2 uses efficient and high temperature resistant heat transfer materials and has high energy recovery efficiency. Waste heat steam generator 2 has a built-in water level sensor, which automatically replenishes water according to the high and low water level changes of the water level sensor. At the same time, the waste heat steam generator is equipped with a safety valve. When the pressure of the waste heat steam generator exceeds the set value, the safety valve automatically discharges and releases pressure to ensure system safety.

[0024] Air preheater 3: By contacting with the exhaust gas, the heat energy in the exhaust gas is transferred to the gaseous medium, which can preheat the combustion air, increase its temperature and enter the VOCs incinerator 1, thereby improving the combustion efficiency. The air preheater 3 uses high-efficiency, high-temperature resistant heat transfer materials and has a high energy recovery efficiency. Specifically, the air inlet of the air preheater 3 is connected to the combustion-supporting fan 6, and the air outlet of the air preheater is connected to the air inlet 17 of the VOCs incinerator to enter the interior of the incinerator; the combustion-supporting fan 6 is also connected to the air inlet of the ever-burning lamp of the VOCs incinerator 1 to support the combustion of the ever-burning lamp. Preferably, as Figure 2 The air outlet of the air preheater is connected to the VOCs incinerator 1 in two ways, one way is connected to the side of the VOCs incinerator 1, so that the entire incinerator is filled with sufficient air, and the other way is connected to the end face of the VOCs incinerator 1 to ensure the full combustion of natural gas and exhaust gas. More preferably, the air outlet of the air preheater is connected to the end face of the VOCs incinerator 1 through an annular uniform air duct 15, which makes the contact between air and natural gas and exhaust gas more uniform and sufficient. The annular uniform air duct can be circular or square.

[0025] Water preheater 4: The water preheater is provided with a cold water inlet and a hot water outlet. The hot water outlet of the water preheater 4 is connected to the water inlet of the waste heat steam generator 2, and the steam outlet of the waste heat steam generator 2 discharges high-temperature steam; it is used to increase the initial temperature of the water entering the waste heat steam generator 2, and further improve the preheating recovery efficiency and the working efficiency of the waste heat steam generator 2. Preferably, the water preheater 4 is connected to the water tank 5, and the water tank 5 replenishes cold water to the water preheater 4. The hot water discharged from the water preheater 4 is transported to the water inlet of the waste heat steam generator 2 through the water tank, and a water replenishment pump 14 is provided between the water tank 5 and the water inlet of the waste heat steam generator 2. Preferably, the steam outlet of the waste heat steam generator 2 is connected to the gas-liquid separator 9, and the liquid outlet of the gas-liquid separator 9 has two outlets, which can be connected to the water inlet of the waste heat steam generator 2 or to the water tank, and the gas outlet of the gas-liquid separator 9 discharges steam.

[0026] Induced draft fan 7: It achieves the negative pressure stability of the incinerator furnace and improves safety.

[0027] The temperature of organic waste gas is relatively high, so in order to ensure the safety of natural gas combustion, the accompanying burner 13 and the waste gas inlet are arranged separately, so that the flame of the accompanying burner 13 can always spray to cover the injection path of the organic waste gas entering the furnace and in the outer flame area of ​​the accompanying burner flame. Preferably, the air inlet 17, the waste gas inlet 16, and the natural gas inlet of the VOCs incinerator are all separately arranged to ensure combustion safety.

[0028] Preferably, the organic waste gas treatment and waste heat recovery system further comprises a chimney 8, and the induced draft fan 7 guides the waste gas into the chimney 8 for discharge.

[0029] The waste heat steam generator 2, the air preheater 3 and the water preheater 4 all include a shell and a tubular heat exchanger arranged in the shell.

[0030] Generally, water vapor in the flue gas is easily condensed into liquid water at the water preheater 4 with a relatively low temperature. In order to prevent the water vapor in the flue gas from condensing into liquid water and remaining in the device, preferably, a condensed water outlet is provided on the pipeline between the water preheater 4 and the chimney and / or on the shell of the water preheater 4.

[0031] Preferably, the inner surfaces of the shells of the waste heat steam generator 2, the air preheater 3 and the water preheater 4 are coated with a fluorine-resistant coating, such as a carbon fiber layer.

[0032] In terms of control, temperature sensors, pressure transmitters, etc. are set up for data collection and transmitted to the PLC controller, so as to control the electric regulating valve, induced draft fan inverter, combustion-supporting fan inverter, etc.

[0033] Specifically, a temperature sensor 10 is provided in the furnace of the VOCs incinerator 1 and / or on the connecting pipeline between the waste heat steam generator 2 and the air preheater 3 and / or at the outlet of the induced draft fan. The temperature of the furnace of the VOCs incinerator is collected and fed back to the accompanying burner 13 to control the conversion of large and small fires, thereby achieving the purpose of energy saving.

[0034] Specifically, a first pressure transmitter 11 is arranged in the furnace of the VOCs incinerator 1, and pressure data is collected and transmitted to the PLC controller. The frequency converter of the induced draft fan 7 is controlled by the PLC, thereby controlling the rotation speed of the induced draft fan 7 and controlling the furnace pressure of the VOCs incinerator to be constant.

[0035] Specifically, the second pressure transmitter 12 is electrically connected to the combustion-supporting fan 6 through a PLC controller. Preferably, a combustion-supporting fan with variable frequency control is provided, and a second pressure transmitter 12 and a temperature sensor 10 are arranged in the pipeline between the air preheater outlet and the VOCs incinerator 1. The fan frequency under different working conditions can be automatically adjusted by setting the wind pressure to achieve a reasonable ratio of combustible exhaust gas and combustion-supporting air.

[0036] Preferably, at the exhaust gas input end of the VOCs incinerator 1, in order to balance the pressure of the exhaust gas pipeline and facilitate unified control, the exhaust gas pipeline is respectively provided with a third pressure transmitter near the production line, and the exhaust gas pipeline is respectively provided with an electric regulating valve before entering the VOCs incinerator, and the opening of the electric regulating valve is adjusted by the input signal of the front-end pressure transmitter. An emergency discharge port is set for each exhaust gas delivery pipeline to prevent the failure of the VOCs incinerator system from affecting the normal production of the production line. When the induced draft fan 7, the combustion-supporting fan 6, the accompanying combustion burner, etc. fail, the system reports a fault, and the fault signal is fed back to the emergency discharge valve on the corresponding exhaust gas delivery pipeline through the PLC, and the electric regulating valve automatically opens, and the exhaust gas is discharged through the bypass pipeline, which does not affect the normal production work.

[0037] Preferably, the fuel supply pipeline system contains a pressure-stabilizing valve, an automatic fuel shut-off valve, and high and low pressure switches. When the gas pressure is low, the automatic fuel shut-off valve cuts off the fuel and the accompanying burner stops working. This is a low-pressure protection function. When the gas pipeline is blocked to the point where the pressure is too high, the fuel is automatically shut off and the accompanying burner stops working. This is a high-pressure protection function.

[0038] The co-burning burner in the furnace of VOCs incinerator 1 is fully automatically controlled and adopts a low-pressure head proportional adjustment gas burner, which can achieve continuous proportional adjustment. The fuel is natural gas and high-pressure ignition, which can adapt to a variety of situations. The combustion system includes a combustion-supporting fan, a high-voltage ignition transformer, a proportional control valve, a UV flame detector, etc. The proportional control valve can adjust its opening according to the temperature change required by the furnace to save fuel; the fuel and combustion-supporting air change synchronously to ensure stable combustion.

[0039] When the utility model is working, the exhaust gas of about 850 degrees Celsius generated after the combustion of the VOCs incinerator enters the shell of the waste heat steam generator through the pipeline, and fully exchanges heat with the tubular heat exchanger in the waste heat steam generator to generate high-temperature steam. At this time, the exhaust gas temperature can be reduced to 200-300 degrees Celsius; then the exhaust gas passes through the tubular heat exchanger in the air preheater 3, and the waste heat is continued to be used to preheat the air. The preheated air is input into the VOCs incinerator, which can improve the combustion efficiency of the VOCs incinerator and further improve the energy efficiency utilization rate of the flue gas waste heat. The exhaust gas temperature can be reduced to 120-150 degrees Celsius; finally, it passes through the tubular heat exchanger in the water preheater 4 to preheat the water entering the waste heat steam generator, and the waste heat of the flue gas is further used to improve the working efficiency of the waste heat steam generator. At this time, the temperature of the exhaust flue gas is 70-80 degrees Celsius. If it is considered necessary, other technologies can be used to further recycle and utilize this part of the flue gas preheating, or it can be directly discharged through the chimney 8. The utility model recovers the flue gas by preheating in the order of the waste heat steam generator 2, the air preheater 3 and the water preheater 4, which can maximize the flue gas recovery rate.

[0040] Control process: When the system starts, the induced draft fan 7 is turned on first, and at the same time, the exhaust gas combustion-supporting fan 6 is started to purge the system. At the same time, the induced draft fan 7 adjusts the induced draft fan to a suitable operating frequency according to the pressure collection in the furnace and the set value of the PLC, and then the accompanying burner starts the startup procedure, purges, and ignites. The induced draft fan 7 again adjusts the induced draft fan to a suitable operating frequency according to the furnace pressure collection and the set value of the PLC. After stable combustion, when the furnace temperature reaches the specified temperature, the corresponding exhaust gas valve is opened; the system automatically adjusts according to the temperature and pressure settings. When the furnace temperature reaches the set maximum operating temperature value, the accompanying burner automatically switches to a low fire state. When the furnace temperature continues to rise and reaches the set maximum upper limit temperature of the furnace, the furnace cooling valve is started to cool the furnace, so that the furnace temperature is always controlled within a reasonable temperature range. When the system is shut down and the production line is finished and the system is shut down, first close the production line valve to stop the exhaust gas input, then turn off the accompanying burner but the blower of the accompanying burner needs to continue blowing air to cool the burner head. At the same time, open the fresh air valve to cool the system. When the furnace temperature drops below the specified temperature, the accompanying burner, combustion-supporting fan, fresh air valve, induced draft fan, etc. can be turned off in turn.

[0041] The utility model has good waste gas treatment effect. After complete combustion, the treatment efficiency can reach 99.9%. The harmful components in the waste gas can be completely destroyed. Through the three-stage heat exchange in a specific order, the waste heat in the waste gas is effectively recovered and used to generate other forms of energy, thereby improving energy utilization efficiency. The waste gas concentration has a high calorific value, which can not only save energy, but also generate a large amount of heat for external supply. The system can reduce the energy consumption of VOCs incinerators, reduce the emission of pollutants such as carbon dioxide, and is environmentally friendly, environmentally friendly and energy-saving.

Claims

1. An organic waste gas treatment and waste heat recovery system, comprising a VOCs incinerator (1), characterized in that: It also includes a waste heat steam generator (2), an air preheater (3), a water preheater (4) and an induced draft fan (7) which are sequentially connected to the exhaust gas outlet of the VOCs incinerator (1); A cold water inlet and a hot water outlet are provided on the water preheater, the hot water outlet of the water preheater (4) is connected to the water inlet of the waste heat steam generator (2), and the steam outlet of the waste heat steam generator (2) discharges high-temperature steam; The air inlet of the air preheater (3) is connected to the combustion-supporting fan (6), and the air outlet of the air preheater is connected to the air inlet (17) of the VOCs incinerator; The combustion-supporting fan (6) is also connected to the air inlet of the ever-burning lamp of the VOCs incinerator (1).

2. The organic waste gas treatment and waste heat recovery system according to claim 1 is characterized in that: The air inlet (17), the exhaust gas inlet (16), and the natural gas inlet of the VOCs incinerator are arranged separately.

3. The organic waste gas treatment and waste heat recovery system according to claim 2 is characterized in that: The air outlet of the air preheater is connected to the VOCs incinerator (1) in two ways, one way is connected to the side of the VOCs incinerator (1), and the other way is connected to the end face of the VOCs incinerator (1).

4. The organic waste gas treatment and waste heat recovery system according to claim 3 is characterized in that: The air outlet of the air preheater is connected to the end surface of the VOCs incinerator (1) through an annular uniform air duct (15).

5. The organic waste gas treatment and waste heat recovery system according to any one of claims 1 to 4, characterized in that: A first pressure transmitter (11) is arranged in the furnace of the VOCs incinerator (1); the first pressure transmitter (11) is electrically connected to a frequency converter of an induced draft fan (7) via a PLC controller to control the rotation speed of the induced draft fan.

6. The organic waste gas treatment and waste heat recovery system according to claim 5 is characterized in that: A second pressure transmitter (12) is arranged in the pipeline between the air preheater outlet and the VOCs incinerator (1), and the second pressure transmitter (12) is electrically connected to the combustion-supporting fan (6) via a PLC controller.

7. The organic waste gas treatment and waste heat recovery system according to claim 6 is characterized in that: A temperature sensor (10) is provided in the furnace of the VOCs incinerator (1) and / or on the pipeline between the air preheater outlet and the VOCs incinerator (1) and / or on the connecting pipeline between the waste heat steam generator (2) and the air preheater (3) and / or at the outlet of the induced draft fan.

8. The organic waste gas treatment and waste heat recovery system according to claim 7 is characterized in that: The water preheater (4) is connected to the water tank (5), the water tank (5) replenishes cold water to the water preheater (4), and the hot water discharged from the water preheater (4) is transported to the water inlet of the waste heat steam generator (2) through the water tank.

9. The organic waste gas treatment and waste heat recovery system according to claim 8, characterized in that: The steam outlet of the waste heat steam generator (2) is connected to the gas-liquid separator (9), the liquid outlet of the gas-liquid separator (9) is connected to the water inlet of the waste heat steam generator (2), the liquid outlet of the gas-liquid separator (9) is also connected to the water tank, and the gas outlet of the gas-liquid separator (9) discharges steam.

10. The organic waste gas treatment and waste heat recovery system according to claim 9, characterized in that: The water in the water tank is also connected to the induced draft fan (7) to cool the induced draft fan (7).

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