A steam generation system based on chemical looping combustion
By flexibly arranging multi-stage superheaters and heat exchangers in the chemical loop combustion system, the problem of insufficient waste heat recovery was solved, achieving efficient high-temperature flue gas heat recovery and high-quality steam production, thus improving system efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- DONGFANG BOILER GROUP OF DONGFANG ELECTRIC CORP
- Filing Date
- 2025-07-03
- Publication Date
- 2026-07-24
AI Technical Summary
Existing chemical loop combustion systems lack specific heat transfer surface layout schemes for waste heat recovery, resulting in inefficient recovery of high-temperature flue gas heat and making them unsuitable for systems with reheat, thus failing to produce high-quality steam.
Multi-stage superheaters, economizers, air preheaters, and evaporative heat exchangers are installed in the tail flue of the air reactor and fuel reactor. By combining different connection methods, the heat transfer surfaces are flexibly arranged to achieve efficient recovery of heat from high-temperature flue gas and produce high-pressure, high-quality steam.
It achieves efficient recovery of high-temperature flue gas heat generated by chemical loop combustion, resulting in lower exhaust gas temperature, high-quality steam production, improved unit efficiency, and applicability to steam demand and reheat systems with different parameters.
Smart Images
Figure CN224551513U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to a steam generation system based on chemical loop combustion. Background Technology
[0002] Chemical looping combustion is a novel carbon capture technology, distinct from traditional methods. It uses an oxygen carrier to transfer oxygen from the air to the fuel, preventing direct contact between air and fuel. This ensures that the carbon dioxide produced during combustion is not diluted by nitrogen in the air, achieving self-separation of carbon dioxide at the fuel conversion source. It represents a disruptive new technology for low-cost, high-efficiency, and large-scale carbon capture. Currently, the chemical looping carbon capture equipment system has completed pilot-scale testing, achieving stable self-heating operation of a megawatt-level chemical looping combustion demonstration unit. However, the high-temperature flue gas from the fuel reactor and air reactor outlets of the pilot unit is used to heat feedwater; efficient waste heat recovery from the system is not implemented.
[0003] The paper "Energy Network Integration and Life Cycle Analysis of Coal Chemical Loop Combustion Power Generation System" discloses a chemical loop combustion system. Chemical loop combustion produces two flue gas streams, which exchange heat in two channels to generate steam suitable for power generation. The steam generated from the two flue gas streams has the same parameters. This steam with identical parameters is then mixed and enters the steam turbine power generation system. The high-temperature flue gas sequentially passes through a superheater, evaporator, and economizer. Boiler water (feedwater) is pumped into the steam generation system to produce steam with different parameters. This system does not specify the connection method between the steam and water media, and because the steam generated from the two flue gas streams has the same parameters, it is not suitable for systems with reheat.
[0004] CA2754948A1 discloses a chemical looping combustion system in which the high-temperature flue gas generated by the air reactor and the fuel reactor respectively enters the waste heat boiler for heat exchange. The patent only states that the waste heat boiler is used to generate steam, without describing the arrangement of the heating surface.
[0005] CN116119611A discloses a steam-powered cycle power generation system. In the power generation module, a waste heat boiler is used to recover waste heat from high-temperature, oxygen-deficient flue gas. The system includes an economizer, evaporator, superheater, and reheater. The flue gas flows through different pressure ranges, enabling the heat to be recovered and utilized in a cascade manner. However, in this patent, the high-temperature flue gas generated by the fuel reactor and air reactor both enter the same heat recovery system, which is detrimental to carbon capture.
[0006] Therefore, current waste heat recovery solutions for large-scale chemical chain applications are still at the conceptual level, and no specific solutions have been proposed for the arrangement of heating surfaces. Summary of the Invention
[0007] The purpose of this invention is to address the aforementioned shortcomings of existing technologies by providing a steam generation system based on chemical loop combustion. This system allows for flexible configuration of the heating surface by selecting various connection methods according to the actual needs of the project's steam and water parameters. It efficiently recovers the heat from the high-temperature flue gas generated by chemical loop combustion, achieving a lower exhaust temperature, while simultaneously producing high-quality steam with higher temperature and pressure ratings, thereby improving unit efficiency.
[0008] To achieve the above objectives, this utility model provides a steam generation system based on chemical looping combustion, comprising a feedwater pump, a blower, a steam drum, and a first evaporative heat exchanger located within an air reactor. Its features include: a superheater, an economizer, and an air preheater are sequentially installed in the tail flue of both the air reactor and the fuel reactor; the feedwater pump is connected to the inlets of the two economizers, and the outlets of both economizers are connected to the steam drum; the steam drum is connected to the lower end of the first evaporative heat exchanger via a downcomer, and the upper end of the first evaporative heat exchanger is connected to the steam drum via a riser; the blower outlet is connected to the inlets of the two air preheaters, and the outlets of the two air preheaters are connected to the lower part of the air reactor; after each stage of superheater is connected, its inlet end is connected to the exhaust pipe of the steam drum, and its exhaust end is connected to the high-pressure cylinder of the steam turbine.
[0009] As a further improvement of this utility model, an evaporative heat exchanger is provided in the flue gas duct at the tail end of the air reactor in front of each stage of superheater, and both ends of the evaporative heat exchanger are connected to the steam drum; this can meet the needs of different main steam pressure parameters.
[0010] As a further improvement of this utility model, an evaporative heat exchanger is provided in the tail flue of the fuel reactor in front of each stage of superheater, and both ends of the evaporative heat exchanger are connected to the steam drum; this can meet the needs of different main steam pressure parameters.
[0011] The superheaters at each stage in the tail flue of the air reactor and the tail flue of the fuel reactor can be connected in series.
[0012] The superheaters at each stage in the tail flue of the air reactor and the tail flue of the fuel reactor can be connected in series. The steam inlet of each of the two rows of superheaters connected in series is connected to the exhaust pipe of the steam drum, and the exhaust end is connected to the high-pressure cylinder of the steam turbine.
[0013] This invention arranges heating surfaces in the tail flue of the fuel reactor and the tail flue of the air reactor. The heating surfaces can be connected in various ways, making the system layout flexible. The evaporation heat exchanger is arranged according to the actual steam and water parameters to efficiently recover the heat from the high-temperature flue gas from the fuel reactor and the air reactor, achieving a lower exhaust temperature and producing high-quality steam with higher temperature and pressure ratings, thereby improving the unit efficiency.
[0014] As a further improvement of this utility model, a desuperheater is provided between each of the two adjacent superheaters connected in series; the main steam temperature can be adjusted.
[0015] A further improvement to this invention is that both the tail flue of the air reactor and the tail flue of the fuel reactor are equipped with one or more reheaters. Each reheater is connected by a pipeline, on which a desuperheater is installed. The exhaust port of the intermediate-pressure cylinder of the steam turbine is connected to the steam inlet of the low-temperature reheater, and the steam outlet of the high-temperature reheater is connected to the air inlet of the intermediate-pressure cylinder of the steam turbine. By introducing a reheat system, the unit efficiency is further improved.
[0016] A further improvement of this utility model is that the inner wall of the first evaporative heat exchanger is lined with a refractory and wear-resistant material; the flue gas velocity in the air reactor 1 is about 5-10 m / s, and the refractory and wear-resistant material can improve the wear resistance of the first evaporative heat exchanger; in order to avoid wear, no screen-type heating surface is arranged in the air reactor.
[0017] This patent applies to parameters where the main steam pressure is subcritical or below. When the main steam pressure is subcritical, only the first evaporator heat exchanger is arranged. When the main steam pressure is below the subcritical parameter, in addition to the first evaporator heat exchanger, a second and a third evaporator heat exchanger also need to be arranged in the tail flue of the air reactor or fuel reactor.
[0018] When the project involves reheating, the steam-water connection can be in series, with the superheater and reheater arranged in multiple stages in two flues; when the project only generates one main steam parameter and does not involve reheating, the steam-water connection can be in series or parallel. When using the series connection, the heating surfaces after the multi-stage desuperheaters are arranged in two flues respectively; when using the parallel connection, desuperheaters are installed on both sides to control the deviation on both sides.
[0019] This invention can efficiently recover the heat from the high-temperature flue gas generated by chemical loop combustion, achieving a lower exhaust temperature, while producing high-quality steam with higher temperature and pressure ratings, thus improving unit efficiency. Attached Figure Description
[0020] Figure 1 This is a structural diagram of the chemical looping combustion device according to Embodiment 1 of this utility model.
[0021] Figure 2 This is a structural diagram of the chemical looping combustion device according to Embodiment 2 of this utility model.
[0022] Figure 3 This is a structural diagram of the chemical looping combustion device according to Embodiment 3 of this utility model. Detailed Implementation
[0023] The present invention will be further described below with reference to the accompanying drawings.
[0024] Example 1
[0025] like Figure 1 As shown, the chemical loop combustion device of this embodiment includes an air reactor 1, a first cyclone separator 2, a fuel reactor 4, and a second cyclone separator 5. The upper outlet of the air reactor 1 is connected to the first cyclone separator 2, the lower part of the first cyclone separator 2 is connected to the fuel reactor 4, and the lower part of the fuel reactor 4 is connected to the lower part of the air reactor 1. Oxygen carrier 8 is added to the fuel reactor 4, and the above components constitute a circulation loop for the oxygen carrier 8. The top of the first cyclone separator 2 is connected to the tail flue 72 of the air reactor, and the top of the second cyclone separator 5 is connected to the tail flue 71 of the fuel reactor. A first air preheater 3 is installed in the tail flue 71 of the fuel reactor. 1. The outlet of the tail flue 71 of the fuel reactor is connected to the CO2 purification device 9. The tail flue 72 of the air reactor is equipped with a second air preheater 32. The outlet of the blower 30 is connected to the inlet of the first air preheater 31 and the second air preheater 32. The outlets of the first air preheater 31 and the second air preheater 32 are connected to the lower part of the air reactor 1. The tail of the tail flue 72 of the air reactor is connected to the chimney 60. The high-temperature flue gas in the air reactor 1 and the fuel reactor 4 enters the tail flue 72 of the air reactor and the tail flue 71 of the fuel reactor, respectively. The flue gas in the tail flue 71 of the fuel reactor is high-concentration CO2, which is beneficial for the low-cost enrichment and recovery of CO2 by the CO2 purification device 9.
[0026] like Figure 1As shown, this embodiment is a steam generation system based on chemical looping combustion, including a feedwater pump 20, a blower 30, a steam drum 10, and a first evaporative heat exchanger 11 located in an air reactor 1. The inner wall of the first evaporative heat exchanger is lined with a refractory and wear-resistant material. A second evaporative heat exchanger 12, a second superheater 42, a second economizer 22, and a second air preheater 32 are sequentially arranged in the tail flue 72 of the air reactor. A third superheater 43, a first superheater 41, a first economizer 21, and a first air preheater 31 are sequentially arranged in the tail flue 71 of the fuel reactor. The feedwater pump 20 is connected to the inlet of the two economizers 21 and 22, and the outlets of the two economizers 21 and 22 are both connected to the steam drum 10. The steam drum 10 is connected to the first evaporative heat exchanger 11 and the second evaporative heat exchanger via a downcomer. The lower end of 12 is connected, and the upper ends of the first evaporative heat exchanger 11 and the second evaporative heat exchanger 12 are connected to the steam drum 10 through riser pipes; the first superheater 41, the second superheater 42 and the third superheater 43 in the tail flue 71 of the fuel reactor and the tail flue 72 of the air reactor are connected in series, and a desuperheater 63 is provided between the first superheater 41 and the second superheater 42, and a desuperheater 64 is provided between the second superheater 42 and the third superheater 43. The steam inlet of the first superheater 41 is connected to the exhaust pipe of the steam drum 10, and the steam exhaust of the third superheater 43 is connected to the high-pressure cylinder of the steam turbine 50; the outlet of the blower 30 is connected to the inlet of the first air preheater 31 and the second air preheater 32, and the outlet of the first air preheater 31 and the second air preheater 32 is connected to the lower part of the air reactor 1;
[0027] In this embodiment, the main steam pressure is 9.8 MPa, and there is no reheat steam.
[0028] Example 2
[0029] like Figure 2 As shown, the difference between this embodiment and Embodiment 1 is only that: the third evaporative heat exchanger 13, the third superheater 43, the second superheater 42, and the first superheater 41 are sequentially arranged in the tail flue 71 of the fuel reactor. The steam drum 10 is connected to both ends of the third evaporative heat exchanger 13 through a downcomer and a riser. The first superheater 41, the second superheater 42, and the third superheater 43 are connected in series. The sixth superheater 46, the fifth superheater 45, and the fourth superheater 44 are arranged in the tail flue 72 of the air reactor. The fourth superheater 44, the fifth superheater 45, and the sixth superheater 46 are connected in series. A desuperheater is provided between each two adjacent superheaters connected in series. The steam inlet of each of the two rows of superheaters connected in series (i.e., the inlet of the first superheater 41 and the fourth superheater 44) is connected to the exhaust pipe of the steam drum 10, and the exhaust end (the outlet of the third superheater 43 and the sixth superheater 46) is connected to the high-pressure cylinder of the steam turbine 50.
[0030] In this embodiment, the main steam pressure is 9.8 MPa, and there is no reheat steam.
[0031] Example 3
[0032] like Figure 3 As shown, the only difference between this embodiment and Embodiment 1 is that: there is no evaporative heat exchanger in the tail flue 72 of the air reactor, and a second reheater 82 and a first superheater 41 are arranged in sequence therein; a third superheater 43, a second superheater 42, and a first reheater 81 are arranged in sequence in the tail flue 71 of the fuel reactor, and the first superheater 41, the second superheater 42 and the third superheater 43 are connected in series, the first reheater 81 and the second reheater 82 are connected in series and a desuperheater 67 is provided between them, the steam exhaust port of the intermediate pressure cylinder of the steam turbine 50 is connected to the steam inlet of the low temperature first reheater 81, and the steam outlet of the high temperature second reheater 82 is connected to the steam inlet of the intermediate pressure cylinder of the steam turbine 50.
[0033] In this embodiment, the main steam pressure is 17.4 MPa, with reheat steam.
[0034] This utility model is applicable to parameters where the main steam pressure is subcritical or below. When the main steam pressure is a subcritical parameter, only the first evaporator heat exchanger 11 is arranged. When the main steam pressure is below the subcritical parameter, in addition to the first evaporator heat exchanger 11, the second evaporator heat exchanger 12 and the third evaporator heat exchanger 13 also need to be arranged in the tail flue of the air reactor or fuel reactor.
[0035] This invention arranges heating surfaces in the tail flue of the fuel reactor and the air reactor, and arranges the evaporative heat exchangers and selects the series or parallel connection method of the heating surfaces of each stage of superheater according to the actual steam and water parameters. When the project has reheat, the steam and water can be connected in series, with the superheater and reheater arranged in multiple stages in the two flues. When the project only produces one main steam parameter without reheat, the steam and water can be connected in series or parallel. When using the series method, the heating surfaces after the multi-stage desuperheater are arranged in the two flues respectively. When using the parallel arrangement, desuperheaters are installed on both sides to control the deviation on both sides. The system layout is flexible and can efficiently recover the heat from the high-temperature flue gas from the fuel reactor and the air reactor to achieve a lower exhaust temperature, while producing high-quality steam with higher temperature and pressure ratings, thus improving unit efficiency. It can also be applied to systems with reheat for steam with different parameters generated by heat exchange between the two flue gas streams.
[0036] The above embodiments have been used to illustrate the invention, but it should be understood that the above embodiments are for illustrative purposes only and are not intended to limit the invention to the scope of the described embodiments.
Claims
1. A steam generation system based on chemical looping combustion, comprising a feedwater pump, a blower, a steam drum, and a first evaporative heat exchanger disposed within an air reactor; characterized in that: Each stage of superheater, economizer, and air preheater is sequentially installed in the tail flue of the air reactor and the tail flue of the fuel reactor. The feedwater pump is connected to the inlet of the two economizers, and the outlet of each economizer is connected to the steam drum. The steam drum is connected to the lower end of the first evaporative heat exchanger through a downcomer, and the upper end of the first evaporative heat exchanger is connected to the steam drum through a riser. The outlet of the blower is connected to the inlet of the two air preheaters, and the outlet of the two air preheaters is connected to the lower part of the air reactor. After the superheaters are connected, their inlet ends are connected to the exhaust pipe of the steam drum, and their exhaust ends are connected to the high-pressure cylinder of the steam turbine.
2. The steam generation system based on chemical looping combustion as described in claim 1, characterized in that: An evaporative heat exchanger is installed in the flue at the tail end of the air reactor in front of each stage of the superheater. Both ends of the evaporative heat exchanger are connected to the steam drum.
3. A steam generation system based on chemical looping combustion as described in claim 1, characterized in that: An evaporative heat exchanger is installed in the tail flue of the fuel reactor in front of each stage of the superheater, and both ends of the evaporative heat exchanger are connected to the steam drum.
4. A steam generation system based on chemical looping combustion as described in claim 1, characterized in that: The superheaters at each stage in the tail flue of the air reactor and the tail flue of the fuel reactor are connected in series.
5. A steam generation system based on chemical looping combustion as described in claim 1, characterized in that: The superheaters at each stage in the tail flue of the air reactor and the tail flue of the fuel reactor are connected in series. The steam inlet of each of the two rows of superheaters connected in series is connected to the exhaust pipe of the steam drum, and the exhaust end is connected to the high-pressure cylinder of the steam turbine.
6. A steam generation system based on chemical looping combustion as described in claim 4 or 5, characterized in that: A desuperheater is installed between each of the two adjacent superheaters connected in series.
7. A steam generation system based on chemical looping combustion as described in any one of claims 1 to 5, characterized in that: Each stage of reheater is installed in the tail flue of the air reactor and the tail flue of the fuel reactor. Each stage of reheater is connected by a pipeline with a desuperheater installed on the pipeline. The exhaust port of the intermediate pressure cylinder of the steam turbine is connected to the steam inlet of the low temperature reheater, and the steam outlet of the high temperature reheater is connected to the air inlet of the intermediate pressure cylinder of the steam turbine.
8. A steam generation system based on chemical looping combustion as described in claim 1, characterized in that: The inner wall of the first evaporative heat exchanger is lined with a fire-resistant and wear-resistant material.