A waste heat boiler reheat system
Patent Information
- Application Number
- CN202522243827.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-23
- Publication Date
- 2026-09-15
- Estimated Expiration
- 2035-10-23
AI Technical Summary
[0009] By adopting this utility model, a specialized heat exchange device is used as an external heater for heating boiler steam with low-corrosive gas (co-fired power plant biogas). This avoids the high-temperature corrosion problem caused by heating boiler steam with waste incineration flue gas. The steam produced by the system also reaches unconventional high-parameter conditions, ultimately achieving the goal of improving power generation efficiency. The air heat exchanger can replace the original steam air preheater, and the combustion hot air no longer needs to be drawn from the boiler or steam turbine for heating, further increasing the steam volume and generating more electricity. The flue gas from the tail of the external heater is directly discharged without entering the waste heat boiler and will not affect the boiler's interior, thus achieving the goal of fully utilizing the low-corrosive gas (power plant biogas).
Smart Images
Figure CN224757015U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of waste heat boiler technology, specifically a waste heat boiler reheating system. Background Technology
[0002] When generating electricity at waste incineration plants, steam produced by boilers is required. These boilers typically use fossil fuels, such as coal, oil, and low-corrosive natural gas. Fossil fuels are non-renewable primary energy sources, and the increasingly tight supply of primary energy has become a major problem severely restricting the sustainable development of the national economy.
[0003] In order to address the shortage of primary energy, develop the economy, improve people's lives, and increase the demand for energy, in addition to strengthening energy conservation and reducing consumption and improving the utilization rate of primary energy, we should also actively seek new energy sources. This has become an inevitable path for the energy strategic development of various countries.
[0004] With rapid economic development and increased environmental awareness, a large amount of urban household waste in my country is now being incinerated, with the steam generated from the boilers used for power generation, turning waste into a valuable resource. However, how to further improve power generation efficiency has long been a concern.
[0005] For the combustion of low-corrosive fuel gas or biogas, existing waste incinerator projects both domestically and internationally have maximized main steam parameters, such as by employing ultra-high pressure and medium temperature methods, to improve power plant efficiency. While there is still room for improvement in steam temperature, potentially reaching high temperatures or above, it is practically impossible to directly increase the steam temperature based on the boiler itself to avoid high-temperature corrosion of the superheater. Otherwise, it would inevitably affect the boiler's reliability and safety. Summary of the Invention
[0006] To solve the above-mentioned technical problems, this utility model provides a waste heat boiler reheating system that can make full use of low-corrosive gas or biogas, increase steam temperature while avoiding high-temperature corrosion.
[0007] The technical solution is as follows: a waste heat boiler reheating system, comprising a waste heat boiler and a steam turbine, characterized in that an external heater is provided between the waste heat boiler and the steam turbine, the external heater being equipped with a superheated steam heat exchanger and an air heat exchanger, the steam outlet of the waste heat boiler being connected to one end of the steam heat exchanger via a first steam pipe, the other end of the steam heat exchanger being connected to the steam turbine via a second steam pipe, one end of the air heat exchanger being supplied with cold air, the other end of the air heat exchanger being connected to the hot air inlet of the waste heat boiler via a hot air pipe, the high-temperature flue gas generated after the combustion of low-corrosive fuel gas or biogas sequentially passing through the steam heat exchanger and the air heat exchanger for heat exchange before entering the chimney, and a recirculated flue gas pipeline being provided between the flue gas inlet and the flue gas outlet of the steam heat exchanger.
[0008] A further feature is that the high-temperature flue gas is generated by a gas burner or a biogas burner; A recirculation fan is installed on the recirculated flue gas pipeline; An air damper is provided between the chimney and the flue gas outlet of the air heat exchanger; The chimney is an on-site chimney located above the external heater.
[0009] By adopting this utility model, a specialized heat exchange device is used as an external heater for heating boiler steam with low-corrosive gas (co-fired power plant biogas). This avoids the high-temperature corrosion problem caused by heating boiler steam with waste incineration flue gas. The steam produced by the system also reaches unconventional high-parameter conditions, ultimately achieving the goal of improving power generation efficiency. The air heat exchanger can replace the original steam air preheater, and the combustion hot air no longer needs to be drawn from the boiler or steam turbine for heating, further increasing the steam volume and generating more electricity. The flue gas from the tail of the external heater is directly discharged without entering the waste heat boiler and will not affect the boiler's interior, thus achieving the goal of fully utilizing the low-corrosive gas (power plant biogas). Attached Figure Description
[0010] Figure 1 This is a schematic diagram of the system of this utility model. Detailed Implementation
[0011] See Figure 1The waste heat boiler reheating system includes a waste heat boiler 1 and a steam turbine 5. An external heater is installed between the waste heat boiler 1 and the steam turbine 5. The external heater contains a steam heat exchanger 2 and an air heat exchanger 3. The steam outlet of the waste heat boiler 1 is connected to one end of the steam heat exchanger 2 via a first steam pipe. The other end of the steam heat exchanger 2 is connected to the steam turbine 5 via a second steam pipe. Cold air is introduced into one end of the air heat exchanger 3, and the other end of the air heat exchanger 3 is connected to the hot air inlet of the waste heat boiler 1 via a hot air pipe. Low-corrosive fuel gas or co-fired biogas from a power plant is burned in a gas burner or biogas burner 6 to produce high-temperature flue gas, which first passes through the steam heat exchanger 2 to convert the waste heat boiler 1 into a conventional safe operating temperature. Superheated steam at all temperatures (400-480℃) is heated to a higher temperature level (≥480℃) and then sent to turbine 5 for power generation. The flue gas after heat exchange (460℃) is partially sent back to the flue gas inlet of steam heat exchanger 2 for recycling through recirculation pipeline 7 and recirculation fan 8. At the same time, the temperature of the flue gas is reduced from 1700-1800℃ when it is generated by combustion to 700℃. The other part enters air heat exchanger 3 to heat the ambient cold air. The hot flue gas (≤150℃) from air heat exchanger 3 is directly discharged into chimney 9. Chimney 9 is an on-site chimney, directly set above the external superheater, without the need to design an additional flue. A damper 4 is set between chimney 9 and flue gas outlet of air heat exchanger 3.
[0012] In this application, a special heat exchange device is used as an external heater for heating boiler steam by burning low-corrosive gas (co-fired biogas from power plants). Since the biogas production from power plants is unstable and small, the combination of low-corrosive gas as the main component and biogas co-fired not only processes and utilizes biogas but also ensures a sufficient and stable heat load.
Claims
1. A waste heat boiler reheat system comprising a waste heat boiler and a steam turbine, characterized by, An external heater is installed between the waste heat boiler and the steam turbine. The external heater contains a superheated steam heat exchanger and an air heat exchanger. The steam outlet of the waste heat boiler is connected to one end of the steam heat exchanger through a first steam pipe. The other end of the steam heat exchanger is connected to the steam turbine through a second steam pipe. Cold air is introduced into one end of the air heat exchanger, and the other end of the air heat exchanger is connected to the hot air inlet of the waste heat boiler through a hot air pipe. The high-temperature flue gas generated after the combustion of low-corrosive gas or biogas passes through the steam heat exchanger and the air heat exchanger in sequence before entering the chimney. A recirculated flue gas pipeline is installed between the flue gas inlet and the flue gas outlet of the steam heat exchanger.
2. The waste heat boiler reheating system according to claim 1, characterized in that, The high-temperature flue gas is generated by a gas burner or a biogas burner.
3. The waste heat boiler reheating system according to claim 1, characterized in that, A recirculation fan is installed on the recirculated flue gas pipeline.
4. The waste heat boiler reheating system according to claim 1, characterized in that, An air damper is provided between the chimney and the flue gas outlet of the air heat exchanger.
5. A waste heat boiler reheating system according to claim 1, characterized in that, The chimney is an on-site chimney located above the external heater.