Megawatt pressurized bubbling fluidized bed oxygen-enriched combustion test platform and combustion method

Abstract

The invention discloses a megawatt pressurized bubbling fluidized bed oxygen-enriched combustion test platform and a combustion method. The platform comprises a feeding system, a pressure swing adsorption oxygen production and gas inlet system, a deslagging system, an oxygen-enriched combustion reaction system and a flue gas and fly ash sampling treatment system. The feeding system adopts a spiral and star-shaped double-path independent pressure feeding unit, and is provided with a multi-stage stock bin, a drying device and a pipeline cooling structure, so that pressurized continuous feeding is realized, and tempering is prevented; the pressure swing adsorption oxygen generation and gas inlet system generates oxygen-enriched gas through a PSA technology, and the oxygen-enriched gas is mixed with CO2 to form a graded oxygen-enriched atmosphere; according to the oxygen-enriched combustion reaction system, accurate temperature control is achieved through an air distribution plate, a reducer pipe and a partition heat exchange device, and generation of NOx is restrained; the problems of unstable fuel supply, unreliable deslagging, low combustion efficiency, difficulty in CO2 enrichment and the like under the high-pressure oxygen-enriched combustion condition in the prior art can be effectively solved.

Description

Technical Field

[0001] This invention relates to test platforms and combustion methods, and more particularly to a megawatt-level pressurized bubbling fluidized bed oxygen-enriched combustion test platform and combustion method. Background Technology

[0002] With the intensification of global climate change, carbon emissions, especially CO2 emissions, have become a hot issue of widespread international concern. Coal, due to its abundant resources and low cost, occupies an important position in the global energy structure. However, the large amounts of CO2 emitted from coal combustion exacerbate the greenhouse effect, leading to global warming. Oxygen-enriched combustion technology, as a key technology for CO2 capture, can capture CO2 at a relatively low cost while improving combustion efficiency, and has received widespread attention.

[0003] Existing oxy-fuel combustion technologies generally employ combustion units operating under atmospheric pressure, extracting oxygen from the air through an air separation unit to replace conventional air for combustion. While this method effectively improves combustion efficiency, its practical application, particularly for the retrofitting and operation of large-scale coal-fired power plants, still faces numerous challenges, such as large plant footprint, high energy consumption, and high operating costs. Furthermore, high-pressure oxy-fuel combustion, by further enhancing fuel reaction rates and improving combustion stability, has become an effective way to improve combustion efficiency and achieve CO2 capture targets. However, existing high-pressure oxy-fuel combustion technologies are mainly limited to experimental stages and small-scale heat load platforms, making it difficult to meet the demands of megawatt-scale continuous operation, especially in achieving multi-fuel, highly efficient oxy-fuel combustion and continuous, stable ash removal under high pressure.

[0004] In addition, although there are some research reports on pressurized oxygen-enriched combustion in the existing technology, most of these technologies lack practical and operable high-pressure oxygen-enriched combustion devices. Especially under megawatt-level heat input conditions, how to achieve continuous fuel supply, efficient and stable combustion process, CO2 enrichment in flue gas, and effective separation and continuous ash discharge of fly ash remains a series of important technical challenges. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a megawatt-level pressurized bubbling fluidized bed oxygen-enriched combustion test platform to achieve efficient and clean combustion of fuels and efficient enrichment of carbon dioxide in flue gas. On the other hand, it provides a megawatt-level pressurized bubbling fluidized bed oxygen-enriched combustion method.

[0006] Technical solution: The megawatt-level pressurized bubbling fluidized bed oxygen-enriched combustion test platform of the present invention is integrated with a feeding system, a pressure swing adsorption oxygen generation and intake system, a slag discharge system, an oxygen-enriched combustion reaction system, and a flue gas fly ash sampling and treatment system. The feeding system is used to continuously transport fuel and bed material under pressure. The pressure swing adsorption oxygen generation and intake system is used to generate oxygen-rich gas and supply it for combustion. The slag discharge system is used to continuously discharge ash and slag under pressure. The oxygen-enriched combustion reaction system is used to carry out combustion reactions under a pressurized oxygen-enriched atmosphere; The flue gas fly ash sampling and processing system is used to process flue gas and collect samples; The feeding system is connected to the oxygen-enriched combustion reaction system, the pressure swing adsorption oxygen generation and intake system is connected to the oxygen-enriched combustion reaction system, the lower end of the oxygen-enriched combustion reaction system is connected to the slag discharge system, and the upper end is connected to the flue gas and fly ash sampling and treatment system, forming a closed-loop process.

[0007] Preferably, the feeding system includes two independent feeding units: a screw feeder and a star feeder. The screw feeder is used for fuel feeding, and the star feeder is used for bed material feeding.

[0008] Preferably, both the screw feeder and the star feeder include a primary silo, a secondary silo, a drying device, a balancing gas system, inlet and outlet pipelines, and heat exchange components. The primary and secondary silos are connected by a discharge pipe and a needle valve to achieve quantitative transfer under pressure. The secondary silo is equipped with a discharge pipe at the bottom, which is driven by a motor to achieve quantitative feeding and is connected to the oxygen-enriched combustion reaction system.

[0009] Preferably, the star-shaped feed pipe is provided with a supplementary air port for introducing balancing gas to form an isolation layer and prevent backfire; both the spiral feed pipe and the star-shaped feed pipe are provided with pipeline heat exchange devices for cooling the feed channel and preventing premature pyrolysis or combustion of fuel.

[0010] Preferably, the pressure swing adsorption oxygen generation and intake system includes: an air compressor, a C-level filter, a refrigerated dryer, a T-level filter, an A-level filter, an activated carbon filter, an air tank, an adsorption tower, an oxygen tank, a sterilizing filter, an analyzer, a booster pump, and a high-pressure oxygen storage tank. The air is compressed, purified and dried in multiple stages, and then divided into an air combustion branch and an oxygen supply branch. The air combustion branch is supplied to the oxygen-enriched combustion reaction system as primary air. The oxygen supply branch obtains oxygen-enriched air through an adsorption tower and supplies it to the oxygen-enriched combustion reaction system after pressurization.

[0011] Preferably, the slag discharge system is a pressure-resistant and sealed structure, including a slag discharge pipe, a slag cooler, a spiral slag discharge rod, a spiral slag discharge rotor, a slag hopper, a slag discharge outlet, and a slag discharge motor; The slag cooler is equipped with a water-cooled wall for cooling high-temperature ash slag; the spiral slag discharge rod is driven by a slag discharge motor to achieve continuous slag discharge under pressurized conditions.

[0012] Preferably, the oxygen-enriched combustion reaction system comprises, from bottom to top: Reactor primary air inlet, air distribution plate, air chamber, dense phase zone heater, semi-tube water-cooled dense phase zone heat exchanger, dense phase zone riser, reactor secondary air inlet, reducing pipe, dilute phase zone riser, semi-tube water-cooled dilute phase zone heat exchanger one and semi-tube water-cooled dilute phase zone heat exchanger two. The air distribution plate is used to evenly distribute the primary air; the variable diameter pipe connects the riser pipe in the dense phase region and the riser pipe in the dilute phase region to optimize the gas velocity distribution; the secondary air inlet is located at the inlet of the variable diameter pipe and is used to supplement oxygen enrichment.

[0013] Preferably, the upper part of the dilute phase region riser pipe is connected to a flue gas channel, and the flue gas channel is connected to the inlet of the cyclone separator; The flue gas passage is equipped with multiple flue gas blowing ports to prevent ash accumulation and blockage; the cyclone separator is equipped with an ash outlet at the bottom, which is connected to the ash hopper heat exchanger for fly ash cooling and waste heat recovery.

[0014] Preferably, the flue gas and fly ash sampling and treatment system includes: a flue gas outlet, a flue, a flue cooler, a flue gas dust removal device, a flue gas desulfurization device, a flue gas purification device, and a CO2 outlet; The flue gas cooler is equipped with a water-cooled wall for cooling the flue gas; the system has a sampling unit at the flue gas test outlet for collecting flue gas and fly ash samples.

[0015] The megawatt-level pressurized bubbling fluidized bed oxygen-enriched combustion test method of the present invention includes the following steps: The fuel and bed material are placed in the primary hoppers of the screw feeder and the star feeder in the feeding system, respectively. After drying, the moisture in the raw materials is removed. After being regulated by the discharge pipe and needle valve, the materials enter the secondary hopper in sequence. The quantitative feeding is achieved under the drive of the motor, and the materials are sent to the oxygen-enriched combustion reaction system through the screw feeder and the star feeder, respectively. The pressure swing adsorption oxygen generation system is turned on. The air is compressed by the air compressor and then purified and dried in sequence through a C-level filter, a refrigerated dryer, a T-level filter, an A-level filter and an activated carbon filter. After the air tank is stabilized, part of the air is sent to the primary air inlet of the reactor through the air combustion branch for air combustion supply, and the other part of the air enters the adsorption tower to obtain oxygen-enriched gas through the alternating adsorption and desorption process. After being pressurized by the oxygen tank, the oxygen-enriched gas is delivered to the high-pressure oxygen storage tank by the booster pump, and then delivered to the gas supply preheating device and the gas supply mixing device through the gas supply pipeline to achieve combustion control under oxygen-enriched atmosphere conditions. The primary air is evenly fed into the bottom of the reactor through the air distribution plate, so that the particles in the bed are fully fluidized; The dense phase zone heater is started to heat the bed material. The semi-pipe water-cooled heat exchanger outside the riser pipes of the dense phase zone and the dilute phase zone operates simultaneously. Oxygen is supplemented through the secondary air inlet of the reactor to stabilize combustion, and the gas velocity distribution is controlled by adjusting the variable diameter pipe structure to achieve particle gas-solid separation. High-temperature flue gas enters the flue gas channel from the upper part of the riser pipe in the dilute phase zone and achieves gas-solid separation through the cyclone separator; the fly ash at the bottom of the cyclone separator enters the ash hopper heat exchanger through the ash outlet for waste heat recovery, and the fly ash cooled by the ash hopper heat exchanger is discharged through the slag discharge system. After being separated by cyclone, the high-temperature flue gas passes through the flue, flue cooler, flue gas dust removal device, flue gas desulfurization device and flue gas purification device in sequence. In the multi-stage purification process, waste heat is recovered and particulate matter, sulfides and other impurities are removed. Finally, it is discharged through the CO2 outlet. By setting up a sampling and analysis unit at the flue gas test outlet, flue gas and fly ash samples at different stages are collected to evaluate the combustion performance and pollutant emission characteristics during the oxygen-enriched combustion process.

[0016] Beneficial Effects: Compared with existing technologies, this invention has the following significant advantages: 1. Through the coordinated design of structural configuration (dual feeding, graded air distribution, zoned heat exchange, pressure-resistant slag discharge), safety measures (gas replenishment and isolation, cooling and fire suppression, online soot blowing, pressure stabilization and release), and control strategies (linked pressure regulation, linked air distribution, linked slag discharge), it achieves efficient, clean, continuous, and controllable operation under megawatt-level, pressurized oxygen-enriched conditions; 2. Through two independent pressure feeding units (spiral / star type) and a cascaded pressure stabilization structure of primary and secondary silos, combined with the quantitative transfer of the discharge pipe and needle valve, it achieves continuous, uniform, and adjustable supply of fuel and bed material under pressurized conditions, significantly reducing the risks of air lock, blockage, and supply fluctuations; 3. By setting up a supplementary air port in the star-shaped feed pipe and introducing balancing gas to form an isolation layer, while simultaneously arranging pipelines for heat exchange and cooling in the spiral / star-shaped feed pipe, and coordinating pressure regulation and safety release with the silo exhaust port and ball valve, it suppresses backfire and premature pyrolysis / combustion in the pipeline from the source, improving intrinsic safety. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0018] Figure 2 This is a schematic diagram of the feeding system structure of the present invention;

[0019] Figure 3 This is a schematic diagram of the pressure swing adsorption oxygen generation and intake system of the present invention;

[0020] Figure 4 This is a schematic diagram of the slag removal system of the present invention;

[0021] Figure 5 This is a schematic diagram of the oxygen-enriched combustion reaction system of the present invention;

[0022] Figure 6 This is a schematic diagram of the flue gas fly ash sampling and treatment system of the present invention. Detailed Implementation

[0023] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0024] Appendix Figure 1 The system consists of: Feeding System I, Pressure Swing Adsorption Oxygen Generation and Air Intake System II, Slag Discharge System III, Oxygen-Enriched Combustion Reactor System IV, Flue Gas and Fly Ash Sampling and Treatment System V; Screw Feeder A, Rotary Feeder B; Silo Balance Gas Supply System C, Oxygen-Enriched Combustion Reactor Gas Supply System D, Pressure Swing Adsorption Oxygen Generation System E; O2 supply unit 1, CO2 supply units 2-1~2-2, gas preheating device 3-1~3-2, gas mixing device 4-1~4-2, ball valve 5-1~5-43, flow meter 6-1~6-8, electric regulating valve 7-1 for the first-stage silo of the screw feeder, electric regulating valve 7-2 for the first-stage silo of the rotary feeder, balance air inlet 8-1 for the first-stage silo of the screw feeder, balance air inlet 8-2 for the first-stage silo of the rotary feeder, exhaust outlet 9-1 for the first-stage silo of the screw feeder, exhaust outlet 9-2 for the first-stage silo of the rotary feeder, feed inlet 10-1 for the first-stage silo of the screw feeder, feed inlet 10-2 for the first-stage silo of the rotary feeder, feed pipe 11-1 for the first-stage silo of the screw feeder, feed pipe 11-1 for the first-stage silo of the rotary feeder. 11-2, Material pipe; 12-1, primary silo of screw feeder; 12-2, secondary silo of screw feeder; 13, screw feeder drying device; 14-1, primary silo of rotary feeder; 14-2, secondary silo of rotary feeder; 15, rotary feeder drying device; 16-1, discharge pipe of primary silo of screw feeder; 16-2, discharge pipe of primary silo of rotary feeder; 17-1, electric regulating valve of secondary silo of screw feeder; 17-2, electric regulating valve of secondary silo of rotary feeder; 18-1, balance air inlet of secondary silo of screw feeder; 18-2, balance air inlet of secondary silo of rotary feeder; 19-1, exhaust outlet of secondary silo of screw feeder; 19-2, exhaust outlet of secondary silo of rotary feeder; ... 20-1 discharge pipe of primary silo, 20-2 discharge pipe of secondary silo of star-shaped feed device, 21-1 motor of screw feed device, 21-2 motor of star feed device, 22 rotor of star feed device, 23 star feed pipe, 24 screw feed pipe, 25 supplementary air port of star feed device, 26 heat exchange device of screw feed pipe, 27 water-cooled wall inlet of screw feed pipe heat exchange device, 28-1 water-cooled wall outlet of screw feed pipe heat exchange device, 29-1 water-cooled wall inlet of star feed pipe heat exchange device, 28-2 water-cooled wall outlet of star feed pipe heat exchange device, 30 primary air inlet of reactor, 31 air distribution plate, 32 air chamber, 33 dense phase zone heater, 34 semi-tube water-cooled dense phase zone heat exchange device, 25 water-cooled wall inlet of dense phase zone heat exchange device. 8-3, Dense Phase Zone Heat Exchanger Water-Cooled Wall Outlet; 29-3, Dense Phase Zone Rising Pipe; 35, Dilute Phase Zone Rising Pipe; 36, Reactor Secondary Air Inlet; 37, Variable Diameter Pipe; 38, Semi-Pipe Water-Cooled Dilute Phase Zone Heat Exchanger I; 39, Semi-Pipe Water-Cooled Dilute Phase Zone Heat Exchanger I Water-Cooled Wall Inlet; 28-4, Semi-Pipe Water-Cooled Dilute Phase Zone Heat Exchanger I Water-Cooled Wall Outlet; 29-4, Semi-Pipe Water-Cooled Dilute Phase Zone Heat Exchanger II; 40, Semi-Pipe Water-Cooled Dilute Phase Zone Heat Exchanger II Water-Cooled Wall Inlet; 28-5, Semi-Pipe Water-Cooled Dilute Phase Zone Heat Exchanger II Water-Cooled Wall Outlet; 29-5, Reactor Flue Gas Passage; 41, Flue Gas Soot Blowing Ports; 42-1~42-3, Cyclone Separator; 43, Cyclone Separator Ash Outlet; 44, Ash Hopper Heat Exchanger; 45, Ash Hopper Heat Exchanger Heat Exchanger Water-Cooled Wall Inlet; 28-6,Ash hopper heat exchanger heat exchange device water-cooled wall outlet 29-6, ash hopper 46, ash hopper discharge pipe 47, flue gas outlet 48, flue gas return port 49, flue duct 50, flue duct cooler 51, flue duct cooler water-cooled wall inlet 28-7, flue duct cooler water-cooled wall outlet 29-7, pressure reducing valve 52, flue gas test outlet 53, flue gas dust removal device 54, flue gas desulfurization device 55, flue gas purification device 56, CO2 outlet 57, ash hopper outlet 58, flue gas dust removal device outlet 59, flue gas desulfurization device outlet 60, slag discharge pipe 61, slag cooler 62, slag cooler water-cooled wall inlet 28-8, slag cooler water-cooled wall outlet 29-8, spiral slag discharge rod 63, spiral slag discharge rotor 6 4. Slag hopper 65. Slag discharge outlet 66. Slag unloading motor 67. Air compressor 68. Class C filter 69. Refrigerated dryer 70. Class T filter 71. Class A filter 72. Activated carbon filter 73. Air tank 74. Air combustion branch 75. Oxygen supply branch 76. Adsorption tower 77-1~77-2. Venting 78. Oxygen tank 79. Sterilizing filter 80. Analyzer 81. Booster pump 82. High-pressure oxygen storage tank 83. Pneumatic valve 84-1~84-10. Electronic drain 85-1~85-2. Pneumatic regulating valve 86-1~86-3. Check valve 87-1~87-3. Needle valve 88-1~88-7. Screw feed rotor 89.

[0025] This embodiment provides a megawatt-level pressurized bubbling fluidized bed oxygen-enriched combustion test platform, comprising five subsystems: feeding system I, pressure swing adsorption oxygen generation and air intake system II, slag discharge system III, oxygen-enriched combustion reaction system IV, and flue gas fly ash sampling and treatment system V. Each subsystem is connected to a control valve group through high-pressure pipelines and achieves coordinated operation under a unified control system. The platform as a whole can operate stably under pressure at megapascals, with a heat input power reaching the megawatt level.

[0026] As attached Figure 2 As shown, the feeding system I is used to continuously transport fuel and bed material under pressurized conditions.

[0027] Specifically, the feeding system I includes two independent pressure feeding units: a screw feeder A and a star feeder B. The two feeding units are responsible for the pressurized and continuous conveying of fuel and bed material, respectively. Both the screw feeder A and the star feeder B are equipped with a primary silo and a secondary silo, a drying device, a balancing gas system, inlet and outlet pipelines, and a feed pipe heat exchange assembly.

[0028] As attached Figure 3 As shown, the Pressure Swing Adsorption (PSA) oxygen generation and intake system II is used to generate oxygen-rich air and supply it for combustion.

[0029] Specifically, the pressure swing adsorption (PSA) oxygen generation and intake system II includes three independent air supply units: a silo balance gas supply system, an oxygen-enriched combustion reactor gas supply system, and a pressure swing adsorption (PSA) oxygen generation system; it consists of an air compressor, a C-level filter, a refrigerated dryer, a T-level filter, an A-level filter, an activated carbon filter, an air tank, an adsorption tower, a venting system, an oxygen tank, a sterilization filter, an analyzer, a booster pump, and a high-pressure oxygen storage tank.

[0030] The oxygen-enriched gas produced by pressure swing adsorption (PSA) is preheated and mixed with CO2 circulating gas in a certain proportion. The primary air accounts for ≥60% of the total air volume, and the secondary air has a higher oxygen enrichment, so as to achieve staged combustion and temperature zone control. This satisfies the requirements for ignition and early combustion, while ensuring complete combustion and adjustable flame intensity.

[0031] As attached Figure 4 As shown, the slag discharge system III is used to continuously discharge ash and slag under pressure.

[0032] Specifically, the slag discharge system III adopts a pressure-resistant and sealed structure, consisting of a slag discharge pipe, a slag cooler, a spiral slag discharge rod, a spiral slag discharge rotor, a slag hopper, a slag discharge outlet, and a slag discharge motor. The slag cooler is a water-cooled shell with a water-cooled wall inlet and a water-cooled wall outlet for cooling the high-temperature bed material and slag particles. The spiral slag discharge rod is driven by the slag discharge motor, and the bottom of the slag hopper has a slag discharge outlet, thereby achieving continuous slag discharge under pressurized conditions.

[0033] As attached Figure 5 As shown, the oxygen-enriched combustion reaction system IV is used to carry out combustion reactions under a pressurized oxygen-enriched atmosphere.

[0034] Specifically, the oxygen-enriched combustion reaction system IV achieves staged air supply and zoned heat exchange. The oxygen-enriched combustion reaction system IV is arranged from bottom to top as follows: primary air inlet, air distribution plate, air chamber, dense phase zone heater, semi-pipe water-cooled dense phase zone heat exchange device, dense phase zone riser pipe, secondary air inlet, reducing pipe, dilute phase zone riser pipe, semi-pipe water-cooled dilute phase zone heat exchange device one and semi-pipe water-cooled dilute phase zone heat exchange device two.

[0035] The air distribution plate is positioned above the air chamber to evenly distribute the incoming primary air to the bottom of the bed, thereby achieving stable fluidization of fuel particles. The dense phase zone heater is used to heat the bed material or maintain a stable bed temperature. The semi-tube water-cooled dense phase zone heat exchanger is installed on the outer wall of the dense phase zone riser to recover combustion heat and regulate bed temperature. The dense phase zone riser and the dilute phase zone riser are connected vertically by a variable diameter pipe to form a continuous fluidization channel. The reactor secondary air inlet is located at the inlet of the variable diameter pipe to supplement oxygen and adjust combustion intensity. The variable diameter pipe connects the dense phase zone riser and the dilute phase zone riser to adjust the airflow velocity distribution and promote particle gas-solid separation. The outer wall of the dilute phase zone riser is sequentially equipped with a semi-tube water-cooled dilute phase zone heat exchanger and a semi-tube water-cooled dilute phase zone heat exchanger to further recover high-temperature flue gas waste heat and reduce flue gas temperature, thereby improving the overall thermal efficiency of the system.

[0036] Uniform primary air distribution and improved particle fluidization are achieved through air distribution plates and air chambers; variable diameter pipes optimize gas velocity distribution and particle separation, and combined with oxygen-enriched secondary air supply, the combustion process is more complete, resulting in simultaneous improvement in combustion efficiency and thermal efficiency, and significantly reduced operational fluctuations. A semi-tubular water-cooled heat exchanger in the dense phase zone recovers the main exothermic heat and stabilizes the bed temperature; a two-stage water-cooled heat exchanger in the dilute phase zone performs deep waste heat recovery. This combination of dense / dilute phase zone heat extraction and segmented temperature control effectively suppresses peak wall temperatures and thermal stress, preventing slagging and material failure caused by localized overheating.

[0037] The upper part of the riser pipe in the dilute phase zone is connected to a flue gas channel. The outlet of the flue gas channel is connected to the inlet of the cyclone separator, which is used to separate the high-temperature flue gas from the bed material particles. The flue gas channel of the reactor is provided with multiple flue gas blowing ports to prevent high-temperature ash accumulation and blockage.

[0038] The cyclone separator has an ash outlet at its lower part, which is connected to an ash hopper heat exchanger. The ash hopper heat exchanger is mainly used to reduce the temperature of high-temperature fly ash and recover waste heat. The top of the cyclone separator is connected to a flue gas outlet, which is connected in sequence to a flue, a flue gas cooler, a flue gas dust removal device, a flue gas desulfurization device, and a flue gas purification device. Finally, it is discharged through a CO2 outlet. The outer wall of the flue gas cooler is provided with a flue gas cooler water-cooled wall inlet and a flue gas cooler water-cooled wall outlet, which are used to further reduce the flue gas temperature and improve the system's heat recovery efficiency.

[0039] As attached Figure 6 As shown, the flue gas fly ash sampling and processing system V is used to process flue gas and collect samples.

[0040] Specifically, the flue gas fly ash sampling and processing system V includes a flue gas outlet, a flue gas back-blowing port, a flue, a flue gas cooler flue gas test outlet, a flue gas dust removal device, a flue gas desulfurization device, a flue gas purification device, a CO2 outlet, etc., and its main purpose is to collect fly ash and flue gas samples at different stages.

[0041] The feeding system is connected to the oxygen-enriched combustion reaction system, the pressure swing adsorption oxygen generation and intake system is connected to the oxygen-enriched combustion reaction system, the lower end of the oxygen-enriched combustion reaction system is connected to the slag discharge system, and the upper end is connected to the flue gas and fly ash sampling and treatment system, forming a closed-loop process, and can achieve continuous and stable operation with megawatt-level heat input under several megapascals of pressure.

[0042] Optionally, the feeding system includes two independent feeding units: a screw feeder A and a star feeder B; the screw feeder A is used for fuel feeding, and the star feeder B is used for bed material feeding; the screw feeder A includes a primary hopper and a secondary hopper; the star feeder B includes a primary hopper and a secondary hopper.

[0043] Specifically, the primary and secondary hoppers of the screw feeder A are connected by a discharge pipe and a needle valve, and the primary and secondary hoppers of the star feeder B are connected by a discharge pipe and a needle valve. The secondary hopper of the screw feeder A has a discharge pipe at its bottom, and the screw feeder rotor driven by the screw feeder motor achieves quantitative feeding and is connected to the inlet of the oxygen-enriched combustion reaction system IV. The secondary hopper of the star feeder B has a discharge pipe at its bottom, and the star feeder rotor driven by the star feeder motor achieves quantitative feeding and is connected to the inlet of the oxygen-enriched combustion reaction system IV.

[0044] The secondary hopper of the screw feeder A is equipped with a screw feeder drying device, and the secondary hopper of the star feeder B is equipped with a star feeder drying device. These devices are used to pre-dry the fuel entering the reaction system to prevent the fuel from absorbing moisture and clumping or burning unevenly during the feeding process. The screw feeder pipe and the star feeder pipe are respectively connected to the oxygen-enriched combustion reaction system, and a supplementary gas port is set on the star feeder pipe to prevent temperature backflow in the dense phase reactor of the oxygen-enriched combustion reaction system. The screw feeder pipe and the star feeder pipe are respectively equipped with a screw feeder pipe heat exchanger and a star feeder pipe heat exchanger. The heat exchangers are used to reduce the temperature inside the feeder pipe and prevent the fuel from burning prematurely inside the pipe, thereby ensuring the safety and stability of the fuel transportation process.

[0045] The primary and secondary silos in the screw feeder A and the star feeder B are connected by a discharge pipe and a needle valve to achieve pressure stabilization and quantitative feeding under pressure. The primary silo is mainly responsible for temporary storage and pressure reduction of raw materials. The bottom of the secondary silo is connected to the reactor inlet through a discharge pipe, and quantitative and stable feeding is achieved by the corresponding drive mechanism (screw motor + screw rotor / star motor + star rotor).

[0046] By adopting an integrated pressure-resistant slag discharge structure consisting of a spiral slag discharge rod / rotor, a water-cooled slag cooler, and a slag hopper, continuous slag discharge without stopping can be achieved under high-pressure conditions; the slag cooler provides uniform cooling to suppress coking and thermal shock, thereby improving the long-term reliability and sealing of the slag discharge channel.

[0047] Optionally, to suppress backfire and pre-ignition inside the pipe, the star-shaped feed pipe B is equipped with a supplementary gas port, and the balancing gas forms an isolation layer. Both the spiral feed pipe A and the star-shaped feed pipe B are equipped with corresponding pipeline heat exchange devices for cooling. The hopper exhaust port and ball valve work together to implement pressure regulation and safe discharge.

[0048] This embodiment of the platform, by configuring multi-point temperature and pressure sensors, component sensors, branch flow meters, and online sampling ports, combined with modular control and data recording, facilitates systematic experiments such as load transformation, air distribution optimization, and oxygen enrichment ratio and circulation ratio optimization, providing a reliable data foundation for expanding the operating condition window and verifying the model.

[0049] This embodiment also provides a megawatt-level pressurized bubbling fluidized bed oxygen-enriched combustion method, characterized by including the following steps: S1. Pressurized feeding preparation and drying.

[0050] Fuel and bed material are placed in the primary silos of the screw feeder A and the star feeder B, respectively. The fuel and bed material are pre-dried by the screw feeder A and the star feeder B to remove moisture from the raw materials, prevent agglomeration and uneven conveying. After being regulated by the discharge pipe and needle valve, the materials enter the secondary silos in sequence. The material is quantitatively fed under the drive of the motor and sent to the oxygen-enriched combustion reaction system through the screw feeder and the star feeder, respectively.

[0051] Specifically, fuel and bed feed are fed into two separate pressure silos. After drying, pressure regulation, and quantitative transfer, they enter the fluidized bed reactor through spiral / star channels for combustion. During operation, the silo drying device is kept on, providing both preheating and drying functions. This ensures effective humidification and stable delivery of the fuel before feeding, guaranteeing that the fuel remains dry and preventing agglomeration, blockage, and decreased combustion efficiency due to excessive moisture content. The silo balancing gas supply system is activated, and a supplementary gas inlet is opened at the top of the star feed pipe to form a stable gas isolation layer during delivery, effectively reducing the risk of backfire entering the feed pipe. Furthermore, the heat exchangers on the spiral and star feed pipes are activated to cool the feed channels, preventing premature pyrolysis or combustion of the fuel before it enters the dense phase zone of the reactor.

[0052] S2, Oxygen production and supply.

[0053] The pressure swing adsorption (PSA) oxygen generation system is activated. Air is compressed by an air compressor and then purified and dried sequentially through a C-level filter, a refrigerated dryer, a T-level filter, an A-level filter, and an activated carbon filter. After being pressurized by an air tank, a portion of the air is sent to the primary air inlet of the reactor via the air combustion branch for combustion gas supply, while the other portion enters the adsorption tower to obtain oxygen-enriched gas through alternating adsorption and desorption processes. The oxygen-enriched gas is then pressurized by an oxygen tank and delivered to a high-pressure oxygen storage tank by a booster pump, and then delivered to a gas supply preheating device and a gas supply mixing device via a gas supply pipeline to achieve combustion control under oxygen-enriched atmosphere conditions.

[0054] Specifically, O2 is primarily produced through pressure swing adsorption (PSA), while CO2 is supplied via gas cylinders. O2 and CO2 are injected into a preheater for preheating and then mixed in a predetermined ratio before entering the fluidized bed reactor through primary and secondary air inlets, respectively. Primary air accounts for ≥60% of the total air volume, with the remainder being secondary air. The oxygen concentration in the secondary air is higher than that in the primary air to ensure sufficient oxygen supply in the later stages of combustion. The oxygen concentration in the primary air is set according to combustion requirements, generally not less than 21 vol%, to meet the requirements for fuel ignition and initial combustion. This staged air intake method allows for zoned temperature control during combustion, preventing localized overheating, promoting complete fuel combustion, and suppressing the formation of pollutants such as NOx.

[0055] S3, Combustion reaction.

[0056] Primary air is evenly fed into the bottom of the reactor through the air distribution plate to fully fluidize the particles in the bed. The dense phase zone heater is started to heat the bed material. The semi-pipe water-cooled heat exchanger outside the riser pipes of the dense phase zone and the dilute phase zone operates simultaneously to realize dynamic recovery of combustion heat and control of bed temperature. Oxygen is supplemented through the secondary air inlet of the reactor to stabilize combustion, and the gas velocity distribution is controlled by adjusting the variable diameter pipe structure to promote gas-solid separation of particles and ensure the stability and efficiency of the combustion process.

[0057] Specifically, during combustion, the fluidized bed reactor is divided into a dense phase zone and a dilute phase zone. The fuel has a longer and optimized residence time in both zones, thereby improving combustion efficiency. The operating temperature of the dense phase zone is controlled within a suitable range (e.g., 800–900℃), while the temperature of the dilute phase zone is maintained at a lower level (e.g., below 850℃), ensuring complete combustion of the fuel while effectively suppressing the formation of thermal NOx. To further improve temperature control accuracy, external semi-tube spiral heat exchangers are installed in the rising sections of both the dense and dilute phase zones. These exchangers perform segmented heat extraction and regulation based on the real-time temperature conditions of each zone, achieving precise multi-segment temperature control and ensuring the stability of the combustion process and the cleanliness of emissions.

[0058] Under pressurized oxygen-enriched conditions, fuel undergoes fluidized combustion in the bed, and the resulting solid ash gradually settles at the bottom of the bed. During operation, the ash hopper motor is started, driving the spiral ash discharge rotor and ash discharge rod to rotate axially, causing the settled ash to fall onto the spiral blades through the discharge pipe and be conveyed downwards by the spiral drive. The ash then enters the ash cooler, where the high-temperature ash is uniformly cooled through a semi-tubular heat exchange structure and collected in the ash hopper after cooling. This ash discharge method is mechanically driven, overcoming the limitations of traditional gravity-based ash discharge, and can achieve continuous, stable, and reliable ash discharge under pressurized conditions, thereby effectively maintaining the long-term stable operation of the system.

[0059] S4. Separation of flue gas and fly ash.

[0060] High-temperature flue gas enters the flue gas channel from the upper part of the riser pipe in the dilute phase zone and achieves gas-solid separation through the cyclone separator; the fly ash at the bottom of the cyclone separator enters the ash hopper heat exchanger through the ash outlet for waste heat recovery, and the fly ash cooled by the ash hopper heat exchanger is discharged through the slag discharge system; the reactor flue gas channel is equipped with multiple flue gas blowing ports, and regular soot blowing operations are performed to prevent ash accumulation and blockage, and to ensure smooth airflow.

[0061] Specifically, fly ash generated during combustion enters a cyclone separator along with the high-temperature flue gas for gas-solid separation. To prevent fly ash from adhering and depositing on the inner wall of the flue gas channel, soot blowing ports are installed on the flue, and deposited ash is removed by periodic or online purging. This significantly reduces the accumulation of ash in the channel and the risk of blockage, ensuring the smooth flow of flue gas and the safe and reliable operation of the system. Simultaneously, to prevent the formation of coke residue due to the high-temperature flue gas within the cyclone separator, a heat exchange device is installed externally to maintain the stability of the internal temperature of the separator. The separated fly ash is discharged through the lower ash hopper, while the high-temperature CO2-enriched flue gas is diverted from the upper section to the flue gas fly ash sampling and treatment system.

[0062] S5. Flue gas purification and sampling.

[0063] After being separated by cyclone separator, the high-temperature flue gas passes through a flue, a flue cooler, a flue gas dust removal device, a flue gas desulfurization device, and a flue gas purification device in sequence. During the multi-stage purification process, waste heat is recovered and particulate matter, sulfides, and other impurities are removed. Finally, the gas is discharged through the CO2 outlet. The system is equipped with a sampling and analysis unit at the flue gas test outlet to collect flue gas and fly ash samples at different stages to evaluate the combustion performance and pollutant emission characteristics during the oxygen-enriched combustion process.

[0064] Specifically, the high-temperature flue gas produced after fuel combustion under pressurized and oxygen-enriched conditions is first cooled by an external heat exchanger to prevent damage to subsequent purification stages due to excessive temperature. The cooled flue gas then sequentially enters a dust removal unit and a desulfurization unit to remove particulate matter and acidic gases such as SO2, thereby reducing the risk of corrosion to system equipment and minimizing secondary pollution. The purified flue gas further enters a purification unit to separate and concentrate CO2, obtaining a high-purity CO2 source. This step not only ensures that flue gas emissions meet environmental protection requirements but also achieves efficient CO2 capture and resource utilization, providing strong support for carbon emission reduction and carbon recycling.

[0065] S6. Continuous feeding and continuous slag removal mechanism to maintain dynamic balance of bed material.

[0066] Specifically, under pressurized oxygen-enriched conditions, this platform achieves a continuous and stable fuel feeding and slag discharge process through the coordinated operation of a pressure feeding system and a pressure slag discharge system. This mechanism can automatically regulate the accumulation and discharge of bed material within the fluidized bed, maintaining a dynamic material balance in the bed layer, thereby ensuring the stability of system operation and the stability of reaction efficiency.

[0067] Optionally, the fluidized bed reactor includes two zones for heat exchange: a dense phase zone and a dilute phase zone. Through staged heat exchange, the reaction temperature can be precisely controlled, and the generation of thermal NOx can be effectively suppressed. The megawatt-level pressurized bubbling fluidized bed oxygen-enriched combustion test platform operates under pressurized oxygen-enriched conditions. By utilizing the synergistic effect of the pressure feeding system and the pressure slag discharge system, continuous and stable fuel feeding and reliable slag discharge can be achieved.

[0068] in, The megawatt-level pressurized bubbling fluidized bed oxygen-enriched combustion test platform maintains the bed material in a dynamic equilibrium state by automatically adjusting the feed rate, bed pressure, and slag discharge speed, ensuring the stability, high reaction efficiency, and safety of the pressurized oxygen-enriched combustion process. Through the above-mentioned multi-system coupled control and zoned heat exchange method, the technical solution of this invention achieves efficient, clean, and continuous stable operation of fluidized bed combustion under megawatt-level heat input conditions.

[0069] Optionally, the megawatt-level pressurized bubbling fluidized bed oxygen-enriched combustion test platform operates using energy recovery and combustion optimization control methods. Through dynamic adjustment of the heat exchange loop and oxygen supply ratio, it achieves synergistic optimization of combustion efficiency improvement and emission control. in, The control system monitors the temperature, oxygen concentration, flue gas composition, and hot water flow rate parameters in both the dense and dilute phase zones in real time. Based on changes in combustion load, it automatically adjusts the circulating water flow rate and oxygen-enriched gas supply ratio of the semi-pipe water-cooled heat exchanger to maintain energy balance between combustion heat release and heat recovery. During combustion, by optimizing the primary and secondary air distribution ratio and adjusting the oxygen and CO2 circulating gas mixing ratio, a staged oxygen-enriched atmosphere is formed, achieving efficient and stable combustion reaction and low emissions of pollutants such as NOx and CO. Through the aforementioned energy recovery and combustion optimization control methods, the system can achieve efficient energy utilization, precise temperature control, and clean combustion operation under megawatt-level heat input conditions.

[0070] This embodiment can achieve pressure at the megapascal level and heat input at the megawatt level. Accordingly, the inner diameter of the dense phase riser 18 is D, the inner diameter of the dilute phase riser 21 is 1.1D, the height of the dense phase riser 18 is 5.5D, the height of the dilute phase riser 21 is 9.5D, and the height of the reducing pipe 19 is 1.8D.

Claims

1. A megawatt-level pressurized bubbling fluidized bed oxygen-enriched combustion test platform, characterized in that, The platform is integrated with a feeding system, a pressure swing adsorption oxygen generation and intake system, a slag discharge system, an oxygen-enriched combustion reaction system, and a flue gas fly ash sampling and treatment system. The feeding system is used to continuously transport fuel and bed material under pressure. The pressure swing adsorption oxygen generation and intake system is used to generate oxygen-rich air and supply it for combustion. The slag discharge system is used to continuously discharge ash and slag under pressure. The oxygen-enriched combustion reaction system is used to carry out combustion reactions under a pressurized oxygen-enriched atmosphere; The flue gas fly ash sampling and processing system is used to process flue gas and collect samples; The feeding system is connected to the oxygen-enriched combustion reaction system, the pressure swing adsorption oxygen generation and intake system is connected to the oxygen-enriched combustion reaction system, the lower end of the oxygen-enriched combustion reaction system is connected to the slag discharge system, and the upper end is connected to the flue gas and fly ash sampling and treatment system, forming a closed-loop process.

2. The oxygen-enriched combustion test platform according to claim 1, characterized in that, The feeding system includes two independent feeding units: a screw feeder and a star feeder. The screw feeder is used for fuel feeding, and the star feeder is used for bed material feeding.

3. The oxygen-enriched combustion test platform according to claim 2, characterized in that, Both the spiral feeder and the star feeder include a primary silo, a secondary silo, a drying device, a balancing gas system, inlet and outlet pipelines, and heat exchange components. The primary and secondary silos are connected by a discharge pipe and a needle valve to achieve quantitative transfer under pressure. The secondary silo is equipped with a discharge pipe at the bottom, which is driven by a motor to achieve quantitative feeding and is connected to the oxygen-enriched combustion reaction system.

4. The oxygen-enriched combustion test platform according to claim 2, characterized in that, The star-shaped feed pipe is equipped with a supplementary air port to introduce balancing gas to form an isolation layer and prevent backfire; both the spiral feed pipe and the star-shaped feed pipe are equipped with pipeline heat exchange devices to cool the feed channel and prevent premature pyrolysis or combustion of fuel.

5. The oxygen-enriched combustion test platform according to claim 1, characterized in that, The pressure swing adsorption oxygen generation and intake system includes: an air compressor, a C-level filter, a refrigerated dryer, a T-level filter, an A-level filter, an activated carbon filter, an air tank, an adsorption tower, an oxygen tank, a sterilizing filter, an analyzer, a booster pump, and a high-pressure oxygen storage tank. The air is compressed, purified and dried in multiple stages, and then divided into an air combustion branch and an oxygen supply branch. The air combustion branch is supplied to the oxygen-enriched combustion reaction system as primary air. The oxygen supply branch obtains oxygen-enriched air through an adsorption tower and supplies it to the oxygen-enriched combustion reaction system after pressurization.

6. The oxygen-enriched combustion test platform according to claim 1, characterized in that, The slag discharge system is a pressure-resistant and sealed structure, including a slag discharge pipe, a slag cooler, a spiral slag discharge rod, a spiral slag discharge rotor, a slag hopper, a slag discharge outlet, and a slag discharge motor; The slag cooler is equipped with a water-cooled wall for cooling high-temperature ash slag; the spiral slag discharge rod is driven by a slag discharge motor to achieve continuous slag discharge under pressurized conditions.

7. The oxygen-enriched combustion test platform according to claim 1, characterized in that, The oxygen-enriched combustion reaction system comprises, from bottom to top: Reactor primary air inlet, air distribution plate, air chamber, dense phase zone heater, semi-tube water-cooled dense phase zone heat exchanger, dense phase zone riser, reactor secondary air inlet, reducing pipe, dilute phase zone riser, semi-tube water-cooled dilute phase zone heat exchanger one and semi-tube water-cooled dilute phase zone heat exchanger two. The air distribution plate is used to evenly distribute the primary air; the variable diameter pipe connects the riser pipe in the dense phase region and the riser pipe in the dilute phase region to optimize the gas velocity distribution; the secondary air inlet is located at the inlet of the variable diameter pipe and is used to supplement oxygen enrichment.

8. The oxygen-enriched combustion test platform according to claim 7, characterized in that, The upper part of the riser pipe in the dilute phase region is connected to the flue gas passage, and the flue gas passage is connected to the inlet of the cyclone separator; The flue gas passage is equipped with multiple flue gas blowing ports to prevent ash accumulation and blockage; the cyclone separator is equipped with an ash outlet at the bottom, which is connected to the ash hopper heat exchanger for fly ash cooling and waste heat recovery.

9. The oxygen-enriched combustion test platform according to claim 1, characterized in that, The flue gas and fly ash sampling and treatment system includes: a flue gas outlet, a flue, a flue cooler, a flue gas dust removal device, a flue gas desulfurization device, a flue gas purification device, and a CO2 outlet; The flue gas cooler is equipped with a water-cooled wall for cooling the flue gas; the system has a sampling unit at the flue gas test outlet for collecting flue gas and fly ash samples.

10. A test method for oxygen-enriched combustion in a megawatt-level pressurized bubbling fluidized bed, characterized in that, Includes the following steps: The fuel and bed material are placed in the primary hoppers of the screw feeder and the star feeder in the feeding system, respectively. After drying, the moisture in the raw materials is removed. After being regulated by the discharge pipe and needle valve, the materials enter the secondary hopper in sequence. The quantitative feeding is achieved under the drive of the motor, and the materials are sent to the oxygen-enriched combustion reaction system through the screw feeder and the star feeder, respectively. The pressure swing adsorption oxygen generation system is turned on. The air is compressed by the air compressor and then purified and dried in sequence through a C-level filter, a refrigerated dryer, a T-level filter, an A-level filter and an activated carbon filter. After the air tank is stabilized, part of the air is sent to the primary air inlet of the reactor through the air combustion branch for air combustion supply, and the other part of the air enters the adsorption tower to obtain oxygen-enriched gas through the alternating adsorption and desorption process. After being pressurized by the oxygen tank, the oxygen-enriched gas is delivered to the high-pressure oxygen storage tank by the booster pump, and then delivered to the gas supply preheating device and the gas supply mixing device through the gas supply pipeline to achieve combustion control under oxygen-enriched atmosphere conditions. The primary air is evenly fed into the bottom of the reactor through the air distribution plate, so that the particles in the bed are fully fluidized; The dense phase zone heater is started to heat the bed material. The semi-pipe water-cooled heat exchanger outside the riser pipes of the dense phase zone and the dilute phase zone operates simultaneously. Oxygen is supplemented through the secondary air inlet of the reactor to stabilize combustion, and the gas velocity distribution is controlled by adjusting the variable diameter pipe structure to achieve particle gas-solid separation. High-temperature flue gas enters the flue gas channel from the upper part of the riser pipe in the dilute phase zone and achieves gas-solid separation through the cyclone separator; the fly ash at the bottom of the cyclone separator enters the ash hopper heat exchanger through the ash outlet for waste heat recovery, and the fly ash cooled by the ash hopper heat exchanger is discharged through the slag discharge system. After being separated by cyclone, the high-temperature flue gas passes through the flue, flue cooler, flue gas dust removal device, flue gas desulfurization device and flue gas purification device in sequence. In the multi-stage purification process, waste heat is recovered and particulate matter, sulfides and other impurities are removed. Finally, it is discharged through the CO2 outlet. By setting up a sampling and analysis unit at the flue gas test outlet, flue gas and fly ash samples at different stages are collected to evaluate the combustion performance and pollutant emission characteristics during the oxygen-enriched combustion process.

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