Dry quenching waste heat boiler economizer adapting to low-load operation

Abstract

The utility model discloses a dry quenching waste heat boiler economizer adapting to low-load operation, which comprises a flue, an economizer I heat exchange tube and an economizer II heat exchange tube are sequentially arranged in the flue along the flow direction of flue gas, and the inlet end and the outlet end of the economizer I heat exchange tube are respectively communicated with an economizer I inlet header and an economizer I outlet header through pipelines. The inlet end and the outlet end of the economizer II heat exchange pipe are communicated with an economizer II inlet header and an economizer II outlet header through pipelines respectively, and a water supply inlet is communicated with the economizer II inlet header and an economizer I inlet header through water supply pipelines respectively. A valve I and a valve III are respectively arranged on a water supply pipeline which is communicated with the economizer II inlet header and the economizer I inlet header; the economizer II outlet header and the economizer I inlet header are communicated through a pipeline; and a valve II is arranged on the pipeline. According to the utility model, the problem of low-temperature corrosion of the dry quenching flue gas circulating system under low-load operation is solved.

Description

Technical Field

[0001] This utility model relates to the field of dry quenching coke waste heat boiler technology, and in particular to an economizer for a dry quenching coke waste heat boiler adapted to low-load operation. Background Technology

[0002] Dry quenching technology is a major energy-saving and environmental protection technology for coking and integrated steel enterprises. As a crucial component of the dry quenching unit, the rational design of the waste heat boiler is of great significance for the safe and stable operation of the entire dry quenching system. Affected by the development of the steel industry, upgrades to its own environmental protection systems, equipment failures in some coke ovens, or prolonged shutdowns for maintenance, dry quenching systems are prone to low-load operation, even reaching ultra-low loads below 40% of full load. Normally, the flue gas temperature of a dry quenching boiler is 160-180℃; however, under low-load operation, the boiler outlet flue gas temperature may remain below 140℃ for extended periods. SO2 in the circulating flue gas is converted to H2SO4, causing acid corrosion to the boiler tail tubes and flue. After heat exchange in the auxiliary economizer tubes, the flue gas temperature continues to drop below the gas dew point temperature, leading to dew point corrosion in the flue gas circulation equipment.

[0003] Therefore, boiler design needs to be optimized to maintain the circulating flue gas at an appropriate temperature to avoid low-temperature corrosion in the dry quenching tail section of the equipment, thereby improving the overall service life of the dry quenching system. The economizer is located at the boiler tail section where the flue gas temperature is relatively low; therefore, improving the economizer design to influence the boiler exhaust gas temperature is a relatively economical and reasonable measure. Utility Model Content

[0004] To solve the above-mentioned technical problems, this utility model designs an economizer for a dry quenching waste heat boiler that is adapted to low-load operation, in order to solve the low-temperature corrosion problem of the dry quenching flue gas circulation system under low-load operation.

[0005] The present invention adopts the following technical solution:

[0006] An economizer for a dry quenching waste heat boiler adapted to low-load operation includes a flue. Economizer I heat exchange tubes and Economizer II heat exchange tubes are sequentially arranged within the flue along the flue gas flow direction. The inlet and outlet ends of Economizer I heat exchange tubes are connected to Economizer I inlet header and Economizer I outlet header via pipelines, respectively. The inlet and outlet ends of Economizer II heat exchange tubes are connected to Economizer II inlet header and Economizer II outlet header via pipelines, respectively. A feedwater inlet is connected to both Economizer II inlet header and Economizer I inlet header via a feedwater pipeline. Valves I and III are respectively installed on the feedwater pipelines connecting Economizer II inlet header and Economizer I inlet header. Economizer II outlet header and Economizer I inlet header are connected via a pipeline, and valve II is installed on the pipeline.

[0007] Preferably, a flue gas temperature measuring device is installed in the flue between the economizer I heat exchange tube and the economizer II heat exchange tube.

[0008] Preferably, the economizer I outlet header is connected to the steam drum via a pipeline.

[0009] As a preferred option, a safety valve is installed on the water supply pipeline connecting to the inlet header of economizer II.

[0010] Preferably, valve one, valve two, and valve three are shut-off valves.

[0011] The beneficial effects of this utility model are: (1) Under different load operating conditions, the temperature of the boiler circulating flue gas is controlled within a suitable range, thereby avoiding the occurrence of low-temperature corrosion and ensuring the safe operation of the system; (2) This utility model technology can flexibly arrange more stages of economizers as needed, such as economizer II, economizer III, economizer IV, etc., and can control the outlet flue gas temperature under different working conditions more accurately. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of this utility model;

[0013] In the diagram: 1. Economizer I heat exchange tube, 2. Economizer II heat exchange tube, 3. Flue gas temperature measuring device, 4. Economizer II inlet header, 5. Economizer II outlet header, 6. Economizer I inlet header, 7. Economizer I outlet header, 8. Feedwater pipeline, 9. Shut-off valve one, 10. Safety valve, 11. Shut-off valve two, 12. Shut-off valve three, 13. Flue, 14. Steam drum, A. Flue gas inlet, B. Flue gas outlet, C. Feedwater inlet. Detailed Implementation

[0014] The technical solution of this utility model will be further described in detail below through specific embodiments and with reference to the accompanying drawings:

[0015] Example: Figure 1As shown, an economizer for a dry quenching waste heat boiler adapted to low-load operation includes a flue 13. Economizer I heat exchange tube 1 and economizer II heat exchange tube 2 are sequentially arranged along the flue gas flow direction within the flue 13. The inlet and outlet ends of economizer I heat exchange tube 1 are connected to economizer I inlet header 6 and economizer I outlet header 7 respectively via pipelines. The inlet and outlet ends of economizer II heat exchange tube 2 are connected to economizer II inlet header 4 and economizer II outlet header 5 respectively via pipelines. A feedwater inlet C is connected to economizer II inlet header 4 and economizer I inlet header 6 respectively via a feedwater pipeline 8. A shut-off valve 1 9 and a shut-off valve 3 12 are respectively installed on the feedwater pipeline connecting economizer II inlet header 4 and economizer I inlet header 6. Economizer II outlet header 5 and economizer I inlet header 6 are connected by a pipeline, and a shut-off valve 2 11 is installed on the pipeline.

[0016] A flue gas temperature measuring device 3 is installed inside the flue duct 13 between the heat exchange tube 1 of economizer I and the heat exchange tube 2 of economizer II. The outlet header 7 of economizer I is connected to the steam drum 14 via a pipeline. A safety valve 10 is installed on the feedwater pipeline connected to the inlet header 4 of economizer II.

[0017] Under normal operating conditions, shut-off valve 312 is closed, and feedwater enters from feedwater inlet C, passing sequentially through feedwater pipe 8, shut-off valve 19, economizer II inlet header 4, economizer II heat exchange tube 2, economizer II outlet header 5, shut-off valve 21, economizer I inlet header 6, economizer I heat exchange tube 1, and economizer I outlet header 7, before entering steam drum 14. Flue gas in flue 13 enters from flue gas inlet A, undergoes two stages of heat exchange with economizer I heat exchange tube 1 and economizer II heat exchange tube 2, and flows out from flue gas outlet B after cooling.

[0018] Under low-load operation, shut-off valves 1-9 and 11-2 are closed. Feedwater enters from feedwater inlet C, passing sequentially through feedwater pipe 8, shut-off valve 3-12, economizer I inlet header 6, economizer I heat exchanger tube 1, and economizer I outlet header 7 before entering steam drum 14. At this time, there is no circulating water flow in economizer II heat exchanger tube 2, and it does not participate in heat exchange with the circulating flue gas. Safety valve 10 controls the pressure inside economizer II tubes to ensure operational safety. Flue gas enters from flue gas inlet A, exchanges heat with economizer I heat exchanger tube 1 for cooling, and then flows out from flue gas outlet B.

[0019] Through the interlocking control between the flue gas temperature measuring device 3 and the shut-off valves 9, 11, and 12, the valves are automatically closed or opened when the flue gas temperature reaches a certain value, thereby controlling the heat exchange between the flue gas and the economizer and controlling the flue gas temperature.

[0020] The embodiments described above are merely preferred solutions of this utility model and are not intended to limit this utility model in any way. Other variations and modifications are possible without departing from the technical solutions described in the claims.

Claims

1. An economizer for a dry quenching waste heat boiler adapted to low-load operation, comprising a flue, characterized in that, Economizer I heat exchange tubes and Economizer II heat exchange tubes are sequentially arranged along the flue gas flow direction within the flue. The inlet and outlet ends of Economizer I heat exchange tubes are connected to the Economizer I inlet header and Economizer I outlet header via pipelines, respectively. The inlet and outlet ends of Economizer II heat exchange tubes are connected to the Economizer II inlet header and Economizer II outlet header via pipelines, respectively. The water inlet is connected to the Economizer II inlet header and Economizer I inlet header via a water supply pipeline. Valve 1 and Valve 3 are respectively installed on the water supply pipelines connecting the Economizer II inlet header and Economizer I inlet header. The Economizer II outlet header and Economizer I inlet header are connected via a pipeline, and Valve 2 is installed on the pipeline.

2. The economizer for a dry quenching waste heat boiler adapted to low-load operation according to claim 1, characterized in that, A flue gas temperature measuring device is installed inside the flue, between the heat exchange tubes of economizer I and economizer II.

3. The economizer for a dry quenching waste heat boiler adapted to low-load operation according to claim 1, characterized in that, The economizer I outlet header is connected to the steam drum via a pipeline.

4. The economizer for a dry quenching waste heat boiler adapted to low-load operation according to claim 1, characterized in that, A safety valve is installed on the water supply pipeline connecting the inlet header of Economizer II.

5. The economizer for a dry quenching waste heat boiler adapted to low-load operation according to claim 1, characterized in that, Valve 1, Valve 2, and Valve 3 are all shut-off valves.

Images