Boiler system for pure oxygen combustion

Abstract

The application discloses a pure-oxygen combustion boiler system, which comprises a furnace, a first separation assembly, a vaporization heating surface, a superheater, a material leg, a material return device, a air distribution plate, a material feeding device, a second separation assembly, a first coal economizer, a second coal economizer and a flue gas compression and purification assembly, the furnace is provided with a feeding port, a first air inlet and a second air inlet, the feeding port, the first air inlet and the second air inlet are communicated with the furnace, the first separation assembly is communicated with the first air inlet, so that the oxygen separated by the first separation assembly is sent into the furnace as primary air, the first separation assembly is communicated with the second air inlet, so that the oxygen separated by the first separation assembly is sent into the furnace as secondary air, the vaporization heating surface and the superheater are arranged in the furnace, the vaporization heating surface and the superheater are arranged in a spaced mode along the up-down direction and are arranged adjacent to the bottom of the furnace. The pure-oxygen combustion boiler system has the advantages of high combustion efficiency and low energy consumption.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of carbon capture, utilization and storage (CCUS), and particularly relates to a pure oxygen combustion boiler system. BACKGROUND

[0002] "Rich coal, poor oil, and less gas" is the energy structure of China, which determines that China is a large coal consumer.

[0003] Carbon dioxide capture, utilization and storage technology (CCUS) is considered to be one of the key technologies indispensable for China to achieve the carbon neutralization goal. For carbon dioxide capture technology, there are currently three types: pre-combustion capture technology, such as integrated coal gasification combined cycle power generation; combustion capture technology, such as flue gas recirculation oxygen-enriched combustion technology; and post-combustion capture technology, such as solvent absorption. Pre-combustion capture power generation has high net efficiency but complex system, post-combustion capture has large flue gas volume flow and low carbon dioxide partial pressure, and for oxygen-enriched combustion capture, the carbon dioxide concentration in the flue gas can be as high as 90% or more, which does not need to go through a complex separation process and can be directly utilized.

[0004] After carbon dioxide capture and purification, resource utilization can produce huge environmental and economic benefits, and according to different engineering and technical means, it can be divided into carbon dioxide geological utilization, carbon dioxide chemical utilization and carbon dioxide biological utilization. Carbon dioxide enhanced oil recovery technology (CCUS-EOR) is an important part of carbon dioxide geological utilization technology, which uses high pressure to inject carbon dioxide into the oil layer to improve the recovery rate of crude oil. Xinjiang is rich in heavy oil resources, and the oilfield steam injection boiler can produce high temperature and high pressure steam, which is a key equipment for heavy oil thermal recovery, and the carbon dioxide produced by it can greatly improve the economic benefit of the oilfield steam injection boiler and has great application prospect. Based on this, the oxygen-enriched combustion method is applied to the oilfield steam injection boiler to enrich carbon dioxide, and at the same time, the geological utilization of carbon dioxide is realized.

[0005] In related technologies, the invention patent CN106838891A discloses a circulating fluidized bed oxygen-enriched combustion boiler system. The high energy consumption in the air separation oxygen process and the carbon dioxide capture process causes the overall power generation efficiency of the unit to decrease and the operating cost to increase, which is the main obstacle to the large-scale engineering application of the current.

[0006] In addition, in the circulating fluidized bed boiler, after the oxygen concentration of pure oxygen combustion is increased, the problem of mismatching between oxygen distribution and fuel combustion is prone to occur, which causes the oxygen concentration in the lower part of the combustion chamber of the circulating fluidized bed boiler to be too high, and local overheating is caused, thereby affecting the efficient and stable operation of the circulating fluidized bed boiler. The invention patent CN11094722A discloses a fluidized bed oxygen carrier assisted oxygen-enriched combustion system and method, which uses an oxygen carrier as a bed material, adjusts and controls coal combustion by the oxygen carrying and releasing of the oxygen carrier, improves the uniformity of furnace heat distribution, and ensures the stable operation of the equipment, thereby overcoming the difficult problem of uneven oxygen distribution in the existing fluidized bed oxygen-enriched combustion, but the solid-solid reaction regulation and control of the fuel and the oxygen carrier (metal oxide) in the upper part of the furnace is difficult, and the heating surface arrangement is difficult to realize under the pure oxygen combustion condition. SUMMARY

[0007] The present application aims to at least partially solve one of the technical problems in the related art.

[0008] To this end, an embodiment of the present application proposes a pure oxygen combustion boiler system with low energy consumption and high combustion efficiency.

[0009] The pure oxygen combustion boiler system according to the embodiment of the present application comprises: a furnace chamber, the furnace chamber has a feeding port, a first air inlet and a second air inlet, the feeding port, the first air inlet and the second air inlet are all in communication with the furnace chamber, the first air inlet is adapted to pass in primary air, and the second air inlet is adapted to pass in secondary air; a first separation assembly, the first separation assembly is in communication with the first air inlet, so that the oxygen separated by the first separation assembly is sent into the furnace chamber as primary air, and the first separation assembly is in communication with the second air inlet, so that the oxygen separated by the first separation assembly is sent into the furnace chamber as secondary air; a vaporization heating surface and a superheater, the vaporization heating surface and the superheater are both arranged in the furnace chamber, the vaporization heating surface and the superheater are arranged in a spaced manner along the up-down direction, and the vaporization heating surface and the superheater are arranged adjacent to the bottom of the furnace chamber.

[0010] The pure oxygen combustion boiler system according to the embodiment of the present application solves the problem of local overheating caused by too high oxygen concentration by arranging the vaporization heating surface and the superheater, and cancels the flue gas recirculation device in the related art, thereby reducing the energy consumption of the operation of the pure oxygen combustion boiler system.

[0011] In some embodiments, the boiler system is a circulating fluidized bed, the fluidized bed has an average particle size of bed material less than or equal to 200 μm, the fluidized bed has a bed pressure drop of 6000 Pa-8000 Pa, the fluidized bed has a bed temperature of 850 ℃-900 ℃, the fluidized bed has an oxygen content in flue gas at the furnace outlet less than or equal to 4.50%, the fuel in the fluidized bed has an average particle size less than or equal to 1 mm, the fluidized bed has a fluidization velocity at the bottom of the furnace of 0.8 m / s-1.6 m / s, and the fluidized bed has a flue gas velocity at the upper part of the furnace of 2.06 m / s-2.48 m / s.

[0012] In some embodiments, the boiler system further comprises a wind distribution plate arranged at the bottom of the furnace, the distance between the second air inlet and the wind distribution plate is L1, the height of the furnace is L2, the ratio between L1 and L2 is 17%-22%, and the ratio between the content of primary air in the furnace and the content of secondary air in the furnace is 16%-24%.

[0013] In some embodiments, the furnace comprises a third portion, a second portion and a first portion sequentially connected in an up-down direction, and in a projection plane perpendicular to the up-down direction, the projection of the third portion is located in the first portion, and the cross-sectional area of the second portion gradually decreases in a direction away from the first portion.

[0014] In some embodiments, the boiler system further comprises a second separation assembly and a flue, one end of the second separation assembly is in communication with one end of the furnace, so that the second separation assembly separates materials in flue gas flowing out of the furnace, and the flue is in communication with the top of the second separation assembly, so that the flue gas separated by the second separation assembly flows into the flue.

[0015] In some embodiments, the boiler system further comprises a return feeder and a leg, both ends of the leg are in communication with the second separation assembly and the return feeder respectively, and the return feeder is in communication with the furnace, so that the materials separated by the second separation assembly flow into the furnace through the leg and the return feeder.

[0016] In some embodiments, the boiler system further comprises a first economizer and a second economizer, both the first economizer and the second economizer are arranged in the flue, and the first economizer and the second economizer are arranged at intervals along the extension direction of the flue.

[0017] In some embodiments, the pure oxygen combustion boiler system further includes a flue gas compression and purification component disposed within the flue. The flue gas compression and purification component is adapted to be directed to an oil field so that the flue gas compression and purification component compresses and condenses carbon dioxide to be transported to the oil field for oil displacement. The superheater is adapted to be directed to the oil field so that the superheated steam flowing out of the superheater flows into the oil field for heavy oil thermal recovery.

[0018] In some embodiments, the distance between the evaporative heating surface and the superheater is 180mm-210mm.

[0019] In some embodiments, the pure oxygen combustion boiler system further includes a fuel bin and a feeder. The fuel bin is adapted to store fuel, and the feeder is connected to both the fuel bin and the furnace so that fuel flowing out of the fuel bin flows into the furnace through the feeder. Attached Figure Description

[0020] Figure 1 This is a pure oxygen combustion boiler system according to an embodiment of the present invention.

[0021] 100 boiler systems using pure oxygen combustion;

[0022] Furnace 1; Part 11; Part 22; Part 33;

[0023] 2. First separation component; 3. Material leg; 4. Return feeder; 5. First fan; 6. Air distribution plate; 7. Second fan; 8. Third fan; 9. Second separation component; 10. Fuel bin; 101. Feeder; 102. Evaporation heating surface; 103. Superheater; 104. First economizer; 105. Second economizer; 106. Fourth fan; 107. Flue gas compression and purification component; 108. Oil field; 109. Flue. Detailed Implementation

[0024] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0025] A boiler system for pure oxygen combustion according to an embodiment of the present invention is described below with reference to the accompanying drawings.

[0026] like Figure 1 As shown, the pure oxygen combustion boiler system according to an embodiment of the present invention includes a furnace 1, a first separation component 2, an evaporation heating surface 102, and a superheater 103.

[0027] The furnace 1 has a feed inlet, a first air inlet, and a second air inlet. All three inlets are connected to the furnace 1. The first air inlet is suitable for introducing primary air, and the second air inlet is suitable for introducing secondary air. Specifically, as follows...Figure 1 As shown in the figure, the primary air can flow into the furnace 1 through the first air inlet, the secondary air can flow into the furnace 1 through the second air inlet, and the fuel flows into the furnace 1 through the feeding port, so that the fuel is fully combusted in the furnace 1 under the action of the primary air and the secondary air.

[0028] The first separation assembly 2 is communicated with the first air inlet, so that the oxygen separated by the first separation assembly 2 is sent into the furnace as the primary air, and the first separation assembly 2 is communicated with the second air inlet, so that the oxygen separated by the first separation assembly 2 is sent into the furnace 1 as the secondary air. Specifically, as shown in the figure, Figure 1 The first separation assembly 2 is an air separation device, which can separate oxygen in air, and the first separation assembly 2 has a first port and a second port. The first port of the first separation assembly 2 is communicated with the first air inlet through the air pipe, so that the pure oxygen separated by the first separation assembly 2 flows into the furnace 1 as the primary air, and the second port of the first separation assembly 2 is communicated with the second air inlet through the air pipe, so that the pure oxygen separated by the first separation assembly 2 flows into the furnace 1 as the secondary air.

[0029] The evaporation heating surface 102 and the superheater 103 are arranged in the furnace 1, and the evaporation heating surface 102 and the superheater 103 are arranged in the up-down direction and are arranged adjacent to the bottom of the furnace 1. Specifically, as shown in the figure, Figure 1 The evaporation heating surface 102 is a buried pipe evaporation heating surface, and the superheater 103 is a buried pipe superheater. The evaporation heating surface 102 and the superheater 103 are arranged inside the furnace 1 and adjacent to the bottom of the furnace 1. The evaporation heating surface 102 and the superheater 103 are arranged in the up-down direction and are arranged adjacent to the bottom of the furnace 1. The arrangement position of the evaporation heating surface 102 and the superheater 103 can be set according to the actual situation, for example, the evaporation heating surface 102 is arranged above the superheater 103, or the evaporation heating surface 102 is arranged below the superheater 103, etc. Since the oxygen content at the bottom of the furnace 1 is too high when pure oxygen is burned, and the content at the top is relatively low, it will cause the bottom of the furnace 1 to burn fiercely and the temperature to be high. Therefore, the evaporation heating surface 102 and the superheater 103 are arranged adjacent to the bottom of the furnace 1, so as to solve the problem of local over-temperature caused by too high oxygen concentration at the lower part of the furnace 1.

[0030] The pure oxygen combustion boiler system 100 of the embodiment of the present application, due to the fact that the flue gas generated by pure oxygen combustion is too little (the nitrogen content in the pure oxygen combustion flue gas is extremely small), the heat taken away by the flue gas flowing out of the furnace is too little, and in the related art, the superheater is arranged in the flue. Therefore, it is difficult for the working medium in the superheater in the related art to be heated to superheated steam in the flue. Therefore, the superheater 103 is arranged inside the furnace and close to the bottom of the furnace 1 to ensure that the steam in the superheater 103 is heated, and in addition, the temperature in the pure oxygen combustion furnace is relatively high, therefore, the evaporation heating surface 102 is arranged in the furnace 1 and the evaporation heating surface 102 is arranged along the bottom of the furnace 1, which can solve the problem of local overheating caused by the excessively high oxygen concentration in the furnace 1.

[0031] Due to the fact that the pure oxygen combustion circulating fluidized bed furnace 1 has the combustion rate increased and the flue gas volume greatly reduced with the increase of the oxygen concentration, a series of changes such as gas-solid flow, combustion reaction, heat transfer and mass transfer are caused, and the fine bed material particle size and the coal particle size can still maintain the rapid bed flow state in the upper part of the furnace under the condition that the pure oxygen combustion flue gas volume is very small, therefore, in some embodiments, the boiler system is a circulating fluidized bed, the average particle size of the bed material of the fluidized bed is less than or equal to 200 μm, and the average particle size of the fuel in the fluidized bed is less than or equal to 1 mm. Thus, the rapid fluidization of the circulating fluidized bed can be realized.

[0032] Due to pure oxygen combustion, the combustion in the lower part of the furnace is intense and easy to overheat, and it is necessary to rely on sufficient circulating material to take heat to the upper part of the furnace, and then ensure the uniform temperature distribution in the furnace, therefore, in some embodiments, the bed pressure drop of the fluidized bed is 6000 Pa-8000 Pa. Therefore, the bed pressure of 6000 Pa-8000 Pa is ensured and the average pressure drop in the upper part of the furnace is limited, so that sufficient circulating material and uniform temperature distribution can be ensured.

[0033] Due to the fact that the temperature in the lower furnace 1 is relatively high under the condition of pure oxygen combustion, but the excessively high temperature is not conducive to low nitrogen emission. Thus, in some embodiments, the bed temperature of the fluidized bed is 850 ℃-900 ℃. Thus, the combustion and NOx emission can be controlled, and the emission of NOx is reduced.

[0034] When the oxygen content in the flue gas at the outlet of the furnace 1 of the fluidized bed is greater than 4.50%, the oxygen content in the furnace 1 will be too large, so that the temperature in the furnace 1 is relatively high, which affects the stable and efficient operation of the circulating fluidized bed, and thus in some embodiments, the oxygen content in the flue gas at the outlet of the furnace 1 of the fluidized bed is less than or equal to 4.50%. Thus, it is beneficial to control the combustion temperature in the furnace 1 and ensure the stable and efficient operation of the circulating fluidized bed.

[0035] Since the problem of overheating in the lower part of the furnace caused by pure oxygen combustion is considered to be solved by arranging the pipe-buried evaporation heating surface 102, in order to reduce the wear of the pipe-buried, and at the same time considering that the coal fuel can be normally fluidized after ashing wear, therefore, in some embodiments, the fluidization speed of the bottom of the furnace 1 of the fluidized bed is 0.8-1.6 m / s. Specifically, the fluidization speed of the fluidized bed can be any one of 0.8 m / s, 1.0 m / s, 1.2 m / s, 1.4 m / s, 1.6 m / s, etc. When the fluidization speed is less than 0.8 m / s, it will result in too low fluidization speed, so that the fluidized bed cannot be normally fluidized, and when the fluidization speed is greater than 1.6 m / s, it will result in too large fluidization speed, which will cause wear to the pipe-buried evaporation heating surface 102 and the pipe-buried superheater 103.

[0036] It can be understood that the cross-sectional area of the bottom of the furnace and the lateral row number of the pipe-buried can be controlled so that the fluidization speed of the bottom of the furnace 1 is 0.8-1.6 m / s.

[0037] In order to reduce the generation of NOx, the furnace 1 adopts staged combustion mode, and at the same time considering the problem of fluidization of the bed material in the lower part of the furnace, according to engineering experience, the pure oxygen combustion boiler system 100 further comprises a wind distribution plate 6 arranged at the bottom of the furnace 1, the distance between the second air inlet and the wind distribution plate 6 is L1, the height of the furnace is L2, the ratio between L1 and L2 is 17%-22%, and the ratio of the content of the primary air in the furnace 1 to the secondary air in the furnace 1 is 16%-24%. Thus, the structure of the furnace 1 is more reasonable.

[0038] In some embodiments, the furnace 1 comprises a third part 13, a second part 12 and a first part 11 which are sequentially communicated in the up-down direction, the wind distribution plate is arranged at the lower end of the first part 11, in the projection plane orthogonal to the up-down direction, the projection of the third part 13 is located in the first part 11, and the cross-sectional area of the second part 12 gradually decreases in the direction away from the first part 11. Specifically, as shown in Figure 1 the first part 11 is a dense phase zone, the third part 13 is a dilute phase zone, and the second part 12 is a transition zone. The second part 12 is arranged above the first part 11, and the third part 13 is arranged above the second part 12. The cross-sectional area of the first part 11 is greater than that of the third part 13, and the cross-sectional area of the second part 12 gradually increases from top to bottom, so that the flow rate of the flue gas in the third part 13 is greater than that in the first part 11, and the third part 13 can achieve rapid fluidization.

[0039] In some embodiments, the flue gas velocity at the upper portion of the furnace 1 of the fluidized bed is 2.06 m / s to 2.48 m / s. Specifically, the flue gas velocity of the third portion 13 can be any one of 2.06 m / s, 2.16 m / s, 2.26 m / s, 2.36 m / s, 2.48 m / s, etc., since the amount of flue gas is constant, and the flue gas fluidization velocity is limited so as to satisfy the fast fluidization in the upper dilute phase zone of the furnace.

[0040] In some embodiments, the pure-oxygen combustion boiler system 100 further comprises a second separation assembly 9 and a flue 109, one end of the second separation assembly 9 being in communication with one end of the furnace 1 so that the second separation assembly 9 separates the materials in the flue gas flowing out of the furnace, and the flue 109 being in communication with the top of the second separation assembly 9 so that the flue gas separated by the second separation assembly 9 flows into the flue 109. Specifically, as shown in Figure 1 the second separation assembly 9 is a separator, the inlet of the second separation assembly 9 being in communication with the outlet of the furnace, and the flue gas flowing out of the furnace can flow into the separator so as to separate the materials (bed material and fuel) in the flue gas by the separator, and the separated flue gas flows into the flue 109.

[0041] In some embodiments, the pure-oxygen combustion boiler system 100 further comprises a material leg 3 and a material return device 4, both ends of the material leg 3 being in communication with the second separation assembly 9 and the material return device 4, respectively, and the material return device 4 being in communication with the furnace 1 so that the materials separated by the second separation assembly 9 flow into the furnace 1 through the material leg 3 and the material return device 4. Specifically, as shown in Figure 1 the material leg 3 extends in the up-down direction, and the inlet of the material leg 3 is in communication with the outlet of the second separation assembly 9, the outlet of the material leg 3 is in communication with the inlet of the material return device 4, and the outlet of the material return device 4 is in communication with the furnace 1, so that the materials separated by the second separation assembly 9 re-enter the furnace 1 through the material leg 3 and the material return device 4, thereby improving the utilization rate of the materials and regulating the boiler load.

[0042] It can be understood that the material leg 3 can make the material particles flow smoothly from top to bottom, ensuring that the materials flow smoothly into the furnace 1.

[0043] In some embodiments, the pure-oxygen combustion boiler system 100 further comprises a first economizer 104 and a second economizer 105, both of which are arranged in the flue 109, and the first economizer 104 and the second economizer 105 are arranged at intervals along the extension direction of the flue 109. Specifically, as shown in Figure 1As shown, the first economizer 104 is a high-temperature economizer, the second economizer 105 is a low-temperature economizer, and the number of the first economizer 104 and the second economizer 105 can be set according to actual conditions. In other words, the first economizer 104 and the second economizer 105 can be set as one or multiple. The first economizer 104 is arranged adjacent to the inlet of the flue 109, so that the first economizer 104 and the second economizer 105 absorb the heat of the flue gas in the flue 109, reduce the flue gas exhaust temperature, and improve the thermal efficiency of the boiler system.

[0044] It is worth noting that the flue gas temperature at the outlet of the circulating fluidized bed furnace is low, the amount of flue gas generated by pure oxygen combustion is small, that is, the heat carried away by the flue gas leaving the furnace is very small, and even cannot meet the preheating of the working medium. The heat transfer amount in the main circulating loop of pure oxygen combustion is large, and the economizer is generally arranged in the tail flue. If the superheater 103 is arranged in the tail flue, it is difficult for the heat carried away by the flue gas to heat the saturated steam in the superheater 103 into superheated steam. In addition, there is not enough heat for the preheating of water in the first economizer 104 and the second economizer 105. According to the distribution of heat absorption and heat release, the superheater 103 is arranged in the furnace 1 to generate superheated steam by heat absorption.

[0045] In some embodiments, the pure oxygen combustion boiler system 100 further comprises a flue gas compression purification assembly 107 arranged in the flue 109. The flue gas compression purification assembly 107 is adapted to be connected to the oil field 108, so that the flue gas compression purification assembly 107 compresses and condenses the carbon dioxide to be transported to the oil field 108 to drive oil. The superheater 103 is adapted to be connected to the oil field 108, so that the superheated steam flowing out of the superheater 103 flows into the oil field 108 for heavy oil thermal recovery. Specifically, as shown in Figure 1 The flue gas compression purification assembly 107 is a flue gas compression purification device. The inlet of the flue gas compression purification device is communicated with the outlet of the flue 109. The flue gas flowing out of the flue 109 is compressed and condensed by the flue gas compression purification device to obtain high-purity carbon dioxide, which is transported to the oil field 108 for enhanced oil recovery. The steam generated by the superheater 103 can also be transported into the oil field 108 for heavy oil thermal recovery of the oil field 108, thereby improving the utilization rate of carbon dioxide.

[0046] In some embodiments, the distance between the evaporation heating surface 102 and the superheater 103 is 180-210 mm. Specifically, the distance between the evaporation heating surface 102 and the superheater 103 can be any one of 180 mm, 190 mm, 200 mm, and 210 mm. The distance between the evaporation heating surface 102 and the superheater 103 is 180-210 mm, so that the evaporation heating surface 102 and the superheater 103 are more reasonably arranged, and the heat distribution problem of pure oxygen combustion circulating fluidized bed can be solved.

[0047] Preferably, the evaporating heating surface 102 is arranged at a position 0.5 m away from the bottom air distribution plate, leaving a maintenance space. The buried tube superheater is a serpentine tube arranged at a position 0.2 m away from the evaporating heating surface of the buried tube, and the buried tubes in the evaporating heating surface 102 and the superheater 103 are both front and back wall in-out tubes.

[0048] In some embodiments, the pure-oxygen combustion boiler system 100 further comprises a fuel bin 10 adapted to store fuel and a feeder 101 in communication with the fuel bin 10 and the furnace 1 respectively, so that the fuel flowing out of the fuel bin 10 flows into the furnace 1 through the feeder 101. Specifically, as shown in the figure, the inlet of the feeder 101 is in communication with the outlet of the fuel bin 10, and the outlet of the feeder 101 is in communication with the feeding port of the furnace 1, so that the fuel is transported to the furnace 1 through the fuel bin 10 and the feeder 101. Figure 1

[0049] It can be understood that the feeder 101 can be a belt conveyor, a chain conveyor, etc., and the present application does not make specific limitations.

[0050] In some embodiments, the pure-oxygen combustion boiler system 100 further comprises a first fan 5, a second fan 7, a third fan 8 and a fourth fan 106.

[0051] The two ends of the first fan 5 are in communication with the first air inlet and the first separation assembly 2 respectively. Specifically, as shown in the figure, the first fan 5 is a primary fan, the inlet of the first fan 5 is in communication with the outlet of the first separation assembly 2, and the outlet of the first fan 5 is in communication with the first air inlet of the furnace 1, so that pure oxygen is transported to the furnace 1 as primary air and sent into the furnace 1 through the first fan 5. Figure 1 The two ends of the second fan 7 are in communication with the second air inlet and the first separation assembly 2 respectively. Specifically, as shown in the figure, the second fan 7 is a secondary fan, the inlet of the second fan 7 is in communication with the outlet of the first separation assembly 2, and the outlet of the second fan 7 is in communication with the second air inlet of the furnace 1, so that pure oxygen is transported to the furnace 1 as secondary air and sent into the furnace 1 through the second fan 7.

[0052] Figure 1 The two ends of the third fan 8 are in communication with the material returner 4 and the first separation assembly 2 respectively. Specifically, as shown in the figure, the third fan 8 is a high-pressure Roots fan, the inlet of the third fan 8 is in communication with the outlet of the first separation assembly 2, and the outlet of the third fan 8 is in communication with the material returner 4, so that high-pressure air (loosening air and conveying air) is provided through the third fan 8 to ensure normal material return and control the amount of material return.

[0053] The fourth fan 106 is in communication with the flue 109. Specifically, as shown in the figure, the fourth fan 106 is a high-pressure Roots fan, the inlet of the fourth fan 106 is in communication with the outlet of the first separation assembly 2, and the outlet of the fourth fan 106 is in communication with the flue 109, so that high-pressure air (loosening air and conveying air) is provided through the fourth fan 106 to ensure normal material return and control the amount of material return. Figure 1

[0054] Figure 1 ​​​​As shown, the fourth fan 106 is an induced draft fan, so that the flue gas in the flue 109 is drawn into the flue gas compression purification assembly 107 through the fourth fan 106.

[0055] It is worth mentioning that due to the change of the combustion mode (pure oxygen combustion), the main component of the flue gas is the triatomic gas carbon dioxide and water (different from the main component of the diatomic gas nitrogen in the air), which leads to the flue gas generated under the pure oxygen combustion mode having stronger radiation heat transfer characteristics and higher heat capacity. The physical property parameters of each component of the flue gas under the pure oxygen combustion mode are fitted, and the heat transfer calculation method is improved in the way of component first and then mixing.

[0056] In some embodiments, the content of the primary air and the content of the secondary air in the hearth are 8:2. Thus, the normal fluidization at the bottom of the hearth can be ensured, and the problem of the generation of nitrogen oxides is reduced.

[0057] It can be understood that the air preheater in the circulating fluidized bed is used to reduce the exhaust gas temperature and improve the thermal efficiency of the boiler. The thermal efficiency of the pure oxygen combustion boiler is already high enough. The calculation shows that the thermal efficiency of the boiler will only decrease by 1% when the exhaust gas temperature of the pure oxygen combustion is increased by 65℃. Secondly, there is a risk of oxygen leakage during preheating, so the air preheater is not arranged in the tail flue 109.

[0058] The pure oxygen combustion boiler system 100 of the embodiment of the present application will be described in detail below.

[0059] A 130t / h pure oxygen combustion circulating fluidized bed (rated steam pressure 13.7MPa, rated steam temperature 420℃) is designed by using the technology of the present application. The circulating fluidized bed burns bituminous coal, and the low calorific value is 20000kJ / kg, the industrial analysis data are moisture (Ma) 18.00%, ash (Aa) 21.00%, volatile matter (Va) 41.00%, and the element analysis data are carbon (Cdaf) 50.28%, hydrogen (Hdaf) 3.68%, nitrogen (Ndaf) 0.96%, sulfur (Sdaf) 0.48%, and oxygen (Odaf) 5.60%.

[0060] Under the rated operating condition, the average particle size of the bed material is 150μm, the bed pressure drop is 7000Pa, the bed temperature is controlled at 885℃, and the oxygen content of the flue gas at the outlet of the hearth is controlled at 4%. The ratio of the primary air volume to the secondary air volume is adjusted to be 8:2, the exhaust gas temperature is set to be 150℃, the feed water temperature is set to be 104℃, the thermal efficiency of the boiler under the pure oxygen combustion mode can be as high as 95.01%, and the fuel consumption is 5.02kg / s. The cross-sectional area of the lower part of the hearth 1 is set to be 24.19 square meters, and the width-depth ratio is 2:1, so that the empty tower fluidization speed can reach 0.83m / s. The width of the upper part of the hearth 1 is unchanged, and the depth is reduced to 2.05m, so that the flue gas fluidization speed can reach 2.47m / s, thereby meeting the requirement of fast fluidization.

[0061] The total height of the furnace is 16 m, the distance from the air distribution plate is 6 m, the height of the front and rear walls is 0.5 m, φ76*14 mm buried pipe evaporative heating surface 102 is laid, the horizontal and vertical tube row numbers are 36 and 7 respectively, and the horizontal and vertical relative pitches are 2.11 and 1.45 respectively. The height of the buried pipe superheater 103 is 0.2 m above the buried pipe evaporative heating surface 102, and is laid in three groups, φ70*10 mm, the horizontal and vertical tube row numbers are 31 and 3 respectively, and the horizontal and vertical relative pitches are 2.29 and 2.86 respectively.

[0062] The first economizer 104 is arranged on the upper part of the tail flue 109 (4.50 m*1.00 m), is composed of two horizontal tube groups, is arranged in a straight line and countercurrent, each row of tube bundles is formed by two φ32*5 mm pipes, the horizontal and vertical tube row numbers of each group of the first economizer 104 are 46 and 14 respectively, the horizontal and vertical relative pitches are 3.00 and 1.88 respectively, and the tube group spacing is 0.86 m. The second economizer 105 is arranged on the lower part of the tail flue 109, is composed of five horizontal tube groups, is arranged in a straight line and countercurrent, each row of tube bundles is also formed by two φ32*5 mm pipes, the horizontal and vertical tube row numbers of each group of the second economizer 105 are 57 and 22 respectively, the horizontal and vertical relative pitches are 2.44 and 1.88 respectively, and the tube group spacing is 0.86 m. The heat distribution of the entire newly designed 130 t / h pure oxygen combustion circulating fluidized bed furnace 1 is reasonable, and the heat absorption error of the working medium is controlled within 0.0014%.

[0063] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0064] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise explicitly and specifically limited.

[0065] In the present application, unless specifically defined otherwise, the terms "mount", "connected", "connecting", "fixed", "unfixed", and the like should be construed broadly and can include fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections, or communication connections between each other; direct connections, or indirect connections via an intermediate medium; or internal communication between two elements or interaction between two elements. Unless otherwise specifically defined, the above terms can be interpreted according to the specific meaning in the present application.

[0066] In the present application, unless specifically defined otherwise, the first feature "on" or "under" the second feature can be direct contact between the first and second features, or indirect contact between the first and second features via an intermediate medium. Moreover, the first feature "above", "over", and "on" the second feature can be directly above or obliquely above the second feature, or can only mean that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "under", and "under" the second feature can be directly below or obliquely below the second feature, or can only mean that the horizontal height of the first feature is lower than that of the second feature.

[0067] In the present application, the terms "one embodiment", "some embodiments", "example", "specific example", "some examples" and the like mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. Furthermore, different embodiments or examples described in the present specification and the features of different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0068] Although embodiments of the present application have been shown and described above, it is to be understood that the above-described embodiments are exemplary, and should not be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A boiler system for pure oxygen combustion, characterized in that, include: The furnace chamber includes a third part, a second part, and a first part that are connected sequentially in the vertical direction. In a projection plane orthogonal to the vertical direction, the projection of the third part is located within the first part, and the cross-sectional area of ​​the second part gradually decreases in the direction away from the first part. The furnace has a feed inlet, a first air inlet, and a second air inlet, all of which are connected to the furnace. The first air inlet is suitable for introducing primary air, and the second air inlet is suitable for introducing secondary air. The ratio of the content of primary air to secondary air in the furnace is 16%-24%. The first separation component is connected to the first air inlet so that the oxygen separated by the first separation component is sent into the furnace as primary air. The first separation component is also connected to the second air inlet so that the oxygen separated by the first separation component is sent into the furnace as secondary air. An evaporating heating surface and a superheater are provided inside the furnace. The evaporating heating surface and the superheater are spaced apart in the vertical direction and are arranged near the bottom of the furnace. The system comprises a second separation component, a flue, a return feeder, and a material leg. One end of the second separation component is connected to one end of the furnace so that the second separation component can separate the material from the flue gas flowing out of the furnace. The flue is connected to the top of the second separation component so that the flue gas separated by the second separation component can flow into the flue. The two ends of the material leg are connected to the second separation component and the return feeder, respectively. The return feeder is connected to the furnace so that the material separated by the second separation component can flow into the furnace through the material leg and the return feeder. A high-pressure Roots blower is provided, with its inlet connected to the outlet of the first separation component and its outlet connected to the return feeder. This allows the high-pressure Roots blower to provide high-pressure air, ensuring normal return and controlling the amount of return. A flue gas compression and purification component is provided, which is connected to the flue and is adapted to be directed to an oil field so that carbon dioxide is obtained by compression and condensation and transported to the oil field for oil displacement. The superheater is adapted to be directed to the oil field so that superheated steam flowing out of the superheater flows into the oil field for heavy oil thermal recovery.

2. The pure oxygen combustion boiler system according to claim 1, characterized in that, The boiler system is a circulating fluidized bed, the average particle size of the bed material is less than or equal to 200 μm, the bed pressure drop is 6000 Pa-8000 Pa, the bed temperature is 850℃-900℃, the oxygen content in the flue gas at the furnace outlet is less than or equal to 4.50%, the average particle size of the fuel in the fluidized bed is less than or equal to 1 mm, the fluidization velocity at the bottom of the furnace is 0.8 m / s-1.6 m / s, and the flue gas velocity at the upper part of the furnace is 2.06 m / s-2.48 m / s.

3. The pure oxygen combustion boiler system according to claim 2, characterized in that, It also includes an air distribution plate located at the bottom of the furnace, the distance between the second air inlet and the air distribution plate being L1, the height of the furnace being L2, and the ratio between L1 and L2 being 17%-22%.

4. The pure oxygen combustion boiler system according to claim 1, characterized in that, It also includes a material leg, the two ends of which are respectively connected to the second separation component and the return feeder. The return feeder is connected to the furnace so that the material separated by the second separation component flows into the furnace through the material leg and the return feeder.

5. The pure oxygen combustion boiler system according to claim 1, characterized in that, It also includes a first economizer and a second economizer, both of which are located inside the flue and are spaced apart along the extension direction of the flue.

6. The pure oxygen combustion boiler system according to any one of claims 1-5, characterized in that, The distance between the evaporative heating surface and the superheater is 180mm-210mm.

7. A boiler system for pure oxygen combustion according to any one of claims 1-5, characterized in that, It also includes a fuel bin and a feeder. The fuel bin is adapted to store fuel, and the feeder is connected to both the fuel bin and the furnace so that fuel flowing out of the fuel bin flows into the furnace through the feeder.

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