Boiler exhaust gas temperature adjusting system

Abstract

The utility model discloses a boiler exhaust gas temperature adjusting system. Comprising an exhaust smoke leading-in flue, an induced draft fan, an induced draft fan outlet flue, a heat exchanger, a heat exchanger outlet flue, a desulfurization device inlet temperature measuring point, a desulfurization device, a chimney, a front-stage heater, a final-stage low-pressure heater, a final-stage low-pressure heater inlet connecting pipe, a final-stage low-pressure heater outlet connecting pipe and a final-stage low-pressure heater inlet leading-out pipe. A final-stage low-pressure heater outlet leading-out pipe, a heat exchanger inlet connecting pipe, a heat exchanger outlet connecting pipe, a deaerator, a regulating valve group, a temperature control system and a flow meter are included. By accurately controlling the tail exhaust gas temperature in real time, the efficiency of a boiler unit is improved, the efficiency of a desulfurization system is improved, and safe and stable operation of the desulfurization system is ensured; and meanwhile, the heat exchanger adopts the finned tube which can greatly improve the heat exchange performance of the heat exchanger and reduce the steel consumption.

Description

Technical Field

[0001] The utility model relates to the technical field of boilers, in particular to a boiler exhaust gas temperature regulating system. Background Art

[0002] When fuel containing sulfur or sulfide is burned in a boiler, pollutants such as SO2 will be generated. In order to meet emission standards, most boilers are currently equipped with desulfurization and denitrification systems. Denitrification generally uses a high-temperature denitrification system, and desulfurization generally uses a semi-dry desulfurization system.

[0003] In order to improve boiler efficiency, an air preheater is generally arranged at the rear of the boiler. Air preheater is a heat transfer component that heats air through flue gas. It is widely used in coal-fired and gas-fired boilers to reduce the exhaust gas temperature and improve boiler efficiency.

[0004] SO2 and SO3 in flue gas will transform into each other, and the reaction formula is as follows:

[0005] 2SO2 + O2 → 2SO3

[0006] Since the cold air temperature of the air preheater is low, when the wall temperature is lower than the flue gas acid dew point, SO3 reacts with the moisture in the flue gas to condense on the flue gas side of the air preheater, which has strong adsorption and corrosiveness.

[0007] In the process of high-temperature denitrification, the escape of NH3 is an objective existence. It reacts with SO3 in the flue gas to form ammonium bisulfate. The reaction formula is as follows:

[0008] NH3+ SO3+ H2O → NH4HSO4

[0009] Ammonium bisulfate is in gaseous, liquid and granular states at different temperatures. The melting point of ammonium bisulfate is 147°C and the boiling point is 350°C. It is particularly easy to adhere to the hot surface at the rear of the boiler, especially on the wall of the air preheater tube, forming salt-like ash accumulation, causing corrosion and ash blockage of the preheater, thereby affecting the heat exchange efficiency of the preheater and increasing the exhaust temperature of the boiler.

[0010] The increase of boiler exhaust gas temperature reduces the efficiency of boiler unit. The flue gas temperature of the desulfurization tower at the tail of the boiler is suitable between 120℃ and 160℃. Too high temperature will affect the normal operation and desulfurization effect of the desulfurization equipment. Too high flue gas temperature will not only reduce the utilization efficiency of desulfurizer, but also affect the operation of desulfurization tower, which may cause damage to the desulfurization tower. Utility Model Content

[0011] In order to solve the above technical problems, the utility model designs a boiler exhaust gas temperature adjustment system. By accurately controlling the tail exhaust gas temperature in real time, the efficiency of the boiler unit is improved, the efficiency of the desulfurization system is improved, and its safe and stable operation is ensured.

[0012] The utility model adopts the following technical solutions:

[0013] A boiler exhaust temperature control system comprises an exhaust flue, a desulfurization device and a chimney which are connected in sequence through pipelines, a heat exchanger is arranged between the exhaust flue and the desulfurization device, a heat exchanger outlet flue of the heat exchanger is connected to the desulfurization device through a pipeline, a desulfurization device inlet temperature measuring point is arranged on the heat exchanger outlet flue, an inlet of the heat exchange end of the heat exchanger is connected to a heat exchanger inlet connecting pipe, an outlet of the heat exchange end of the heat exchanger is connected to a heat exchanger outlet connecting pipe, the heat exchanger inlet connecting pipe is respectively connected to a final low-pressure heater inlet outlet pipe and a final low-pressure heater outlet outlet pipe, and a final low-pressure heater inlet outlet pipe and a final low-pressure heater outlet outlet pipe are respectively connected to the final low-pressure heater inlet outlet pipe and the final low-pressure heater outlet outlet pipe. The inlet and outlet of the heater, the inlet of the final low-pressure heater is connected to the final low-pressure heater inlet connecting pipe, the outlet of the final low-pressure heater is connected to the final low-pressure heater outlet connecting pipe, the inlet connecting pipe of the final low-pressure heater is connected to the previous-stage heater, the outlet connecting pipe of the final low-pressure heater is connected to the deaerator, the outlet connecting pipe of the heat exchanger is connected to the deaerator, electric control valves are respectively installed on the inlet lead-out pipe of the final low-pressure heater and the outlet lead-out pipe of the final low-pressure heater, a regulating valve group is connected to the heat exchanger inlet connecting pipe, the regulating valve group is connected to the temperature control system, which is controlled and adjusted by the temperature control system, and the temperature data detected by the desulfurization device inlet temperature measuring point is fed back to the temperature control system.

[0014] Preferably, electric control valves are installed on the final low-pressure heater inlet connecting pipe, the final low-pressure heater outlet connecting pipe, the heat exchanger inlet connecting pipe and the heat exchanger outlet connecting pipe, respectively.

[0015] Preferably, a flow meter is installed on the inlet connecting pipe of the heat exchanger to monitor the water flow entering the heat exchanger in real time.

[0016] Preferably, an induced draft fan is installed between the smoke introduction flue and the heat exchanger, an induced draft fan outlet flue is arranged at the induced draft fan outlet, and the induced draft fan outlet flue is connected to the heat exchanger. The induced draft fan is arranged in front of the heat exchanger, and the heat exchange efficiency of the heat exchanger can be improved by utilizing the temperature rise of the induced draft fan.

[0017] Preferably, the heat exchanger uses finned tubes, which can significantly improve the heat exchange performance of the heat exchanger and reduce steel consumption.

[0018] The beneficial effects of the utility model are as follows: (1) the utility model designs a boiler exhaust temperature regulation system, which improves the efficiency of the boiler unit and the desulfurization system by accurately controlling the tail exhaust temperature in real time, and ensures its safe and stable operation; (2) the heat exchanger adopts finned tubes, which can greatly improve the heat exchange performance of the heat exchanger and reduce steel consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the utility model;

[0020] In the figure: 1. exhaust smoke inlet flue, 2. induced draft fan, 3. induced draft fan outlet flue, 4. heat exchanger, 5. heat exchanger outlet flue, 6. desulfurization device inlet temperature measuring point, 7. desulfurization device, 8. chimney, 9. front-stage heater, 10. final-stage low-pressure heater, 11. final-stage low-pressure heater inlet connecting pipe, 12. final-stage low-pressure heater outlet connecting pipe, 13. final-stage low-pressure heater inlet outlet pipe, 14. final-stage low-pressure heater outlet outlet pipe, 15. heat exchanger inlet connecting pipe, 16. heat exchanger outlet connecting pipe, 17. deaerator, 18. regulating valve group, 19. temperature control system, 20. flow meter. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings:

[0022] Example: Figure 1 As shown, a boiler exhaust temperature control system includes an exhaust smoke inlet flue 1, an induced draft fan 2, an induced draft fan outlet flue 3, a heat exchanger 4, a heat exchanger outlet flue 5, a desulfurization device inlet temperature measuring point 6, a desulfurization device 7, a chimney 8, a front-stage heater 9, a final-stage low-pressure heater 10, a final-stage low-pressure heater inlet connecting pipe 11, a final-stage low-pressure heater outlet connecting pipe 12, a final-stage low-pressure heater inlet lead-out pipe 13, a final-stage low-pressure heater outlet lead-out pipe 14, a heat exchanger inlet connecting pipe 15, a heat exchanger outlet connecting pipe 16, a deaerator 17, a regulating valve group 18, a temperature control system 19, and a flow meter 20.

[0023] The flue gas of the boiler enters the induced draft fan 2 through the exhaust flue 1, and then enters the heat exchanger 4 through the induced draft fan outlet flue 3. The flue gas after heat exchange in the heat exchanger enters the desulfurization tower 7 through the heat exchanger outlet flue 5, and the flue gas after desulfurization is discharged into the atmosphere through the chimney 8. The water from the front stage heater 9 enters the final stage low pressure heater 10 through the final stage low pressure heater inlet connecting pipe 11, and is connected to the deaerator 17 through the final stage low pressure heater outlet connecting pipe 12. The flue gas temperature at the heat exchanger outlet is monitored through the desulfurization device inlet temperature measuring point 6. When the temperature exceeds the set temperature value, the regulating valve group 18 on the heat exchanger inlet pipe 15 is controlled by the temperature control system 19, and the water is introduced into the heat exchanger inlet connecting pipe 15 through the final stage low pressure heater inlet outlet pipe 13 or the final stage low pressure heater outlet outlet pipe 14. After absorbing heat in the heat exchanger 4, the water is connected to the deaerator 17 through the heat exchanger outlet connecting pipe 16 and the final stage low pressure heater outlet connecting pipe 12. The flow meter 20 can monitor the water flow entering the heat exchanger in real time.

[0024] By accurately controlling the tail flue gas temperature in real time, the efficiency of the boiler unit and the desulfurization system can be improved, and their safe and stable operation can be ensured.

[0025] The induced draft fan is arranged in front of the heat exchanger, and the temperature rise of the induced draft fan can be used to improve the heat exchange efficiency of the heat exchanger.

[0026] The heat exchanger uses finned tubes, which can greatly improve the heat transfer performance of the heat exchanger and reduce steel consumption.

[0027] The regulating valve group can adjust the medium flow entering the heat exchanger in real time through the temperature control system, thereby accurately controlling the flue gas temperature at the inlet of the desulfurization device.

[0028] In order to improve the energy efficiency of the system, the water entering the heat exchanger is preferably led out from the outlet connecting pipe of the final low-pressure heater. When the water led out from the outlet connecting pipe of the final low-pressure heater cannot meet the requirements of controlling the inlet flue gas temperature of the desulfurization device within the verification range after entering the heat exchanger for heat exchange, the water entering the heat exchanger can be switched to be led out from the inlet connecting pipe of the final low-pressure heater.

[0029] A flow meter is provided on the heat exchanger inlet connecting pipe to monitor the water flow entering the heat exchanger in real time.

[0030] The above-described embodiment is only a preferred solution of the present invention and does not limit the present invention in any form. There are other variations and modifications without exceeding the technical solution described in the claims.

Claims

1. A boiler exhaust gas temperature control system, comprising an exhaust gas introduction flue, a desulfurization device and a chimney connected in sequence through a pipeline, characterized in that: A heat exchanger is arranged between the exhaust gas introduction flue and the desulfurization device, the heat exchanger outlet flue of the heat exchanger is connected to the desulfurization device through a pipeline, a desulfurization device inlet temperature measuring point is arranged on the heat exchanger outlet flue, the inlet of the heat exchange end of the heat exchanger is connected to the heat exchanger inlet connecting pipe, the outlet of the heat exchange end of the heat exchanger is connected to the heat exchanger outlet connecting pipe, the heat exchanger inlet connecting pipe is respectively connected to the final low-pressure heater inlet lead-out pipe and the final low-pressure heater outlet lead-out pipe, the inlet and outlet of the final low-pressure heater are respectively connected through the final low-pressure heater inlet lead-out pipe and the final low-pressure heater outlet lead-out pipe, the inlet of the final low-pressure heater The inlet is connected to the final-stage low-pressure heater inlet connecting pipe, the outlet of the final-stage low-pressure heater is connected to the final-stage low-pressure heater outlet connecting pipe, the inlet connecting pipe of the final-stage low-pressure heater is connected to the previous-stage heater, the outlet connecting pipe of the final-stage low-pressure heater is connected to the deaerator, the outlet connecting pipe of the heat exchanger is connected to the deaerator, electric control valves are respectively installed on the inlet lead-out pipe of the final-stage low-pressure heater and the outlet lead-out pipe of the final-stage low-pressure heater, a regulating valve group is connected to the temperature control system, which is controlled and regulated by the temperature control system, and the temperature data detected by the inlet temperature measuring point of the desulfurization device is fed back to the temperature control system.

2. A boiler exhaust gas temperature control system according to claim 1, characterized in that: The final-stage low-pressure heater inlet connecting pipe, the final-stage low-pressure heater outlet connecting pipe, the heat exchanger inlet connecting pipe and the heat exchanger outlet connecting pipe are respectively equipped with electric control valves.

3. A boiler exhaust gas temperature control system according to claim 1, characterized in that: A flow meter is installed on the heat exchanger inlet connecting pipe.

4. A boiler exhaust gas temperature control system according to claim 1, characterized in that: An induced draft fan is installed between the smoke exhaust introduction flue and the heat exchanger, an induced draft fan outlet flue is arranged at the induced draft fan outlet, and the induced draft fan outlet flue is connected to the heat exchanger.

5. A boiler exhaust gas temperature control system according to claim 1, characterized in that: The heat exchanger adopts finned tubes.

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