CN219367602U - Pure oxygen combustion system - Google Patents

Abstract

The utility model discloses a pure oxygen combustion system which comprises a circulating fluidized bed hearth, a first separator, an evaporation heating surface, a superheater, a dipleg, a material returning device, an air distribution plate, a feeding device, a second separator, a first coal economizer, a second coal economizer and a flue gas compression and purification assembly, wherein the circulating fluidized bed hearth is provided with a feed inlet, a first air inlet and a second air inlet, the feed inlet, the first air inlet and the second air inlet are all communicated with the hearth, the first separator is communicated with the first air inlet so that oxygen separated by the first separator is fed into the hearth as primary air, the first separator is communicated with the second air inlet so that oxygen separated by the first separator is fed into the hearth as secondary air, the evaporation heating surface and the superheater are both arranged in the hearth, and the evaporation heating surface and the superheater are arranged at intervals along the up-down direction. The pure oxygen combustion system has the advantages of high combustion efficiency, lower energy consumption and the like.

Description

Pure oxygen combustion system

Technical Field

The utility model belongs to the technical field of carbon capture, utilization and sequestration (CCUS), and particularly relates to a pure oxygen combustion system.

Background

Carbon dioxide capture, utilization and sequestration technology (CCUS) is considered to be one of the key technologies essential to our country to achieve the goal of carbon neutralization. For carbon dioxide capture technologies, three main categories are currently involved: pre-combustion capture technologies, such as integrated gasification combined cycle power generation; in-combustion trapping technologies, such as flue gas recirculation oxyfuel combustion technologies; post-combustion capture techniques such as solvent absorption. The system is complex, the volume flow of the trapped smoke after combustion is large, the partial pressure of carbon dioxide is low, and for oxygen-enriched combustion trapping, the concentration of carbon dioxide in the discharged smoke can reach more than 90%, so that the carbon dioxide can be directly utilized without complex separation process.

After the carbon dioxide is captured and purified, the recycling utilization can generate huge environmental benefit and economic benefit, and can be divided into carbon dioxide geological utilization, carbon dioxide chemical utilization and carbon dioxide biological utilization according to different engineering technical means. Carbon dioxide enhanced oil recovery (CCUS-EOR), i.e., injecting carbon dioxide into an oil reservoir at high pressure to enhance the recovery of crude oil, is an important component cavity section in carbon dioxide geological utilization technology. The Xinjiang thick oil has rich resources, the oilfield steam injection boiler can generate high-temperature and high-pressure steam, the Xinjiang thick oil is used as key equipment for thick oil thermal recovery, and simultaneously, the generated carbon dioxide is used for enhanced oil recovery, so that the economic benefit of the oilfield steam injection boiler can be greatly improved, and the Xinjiang thick oil has a huge application prospect. Based on the method, the oxygen-enriched combustion mode is applied to the oilfield steam injection boiler to enrich carbon dioxide, and geological utilization of the carbon dioxide is realized.

In the related art, the utility model patent CN106838891A discloses an oxygen-enriched combustion boiler system of a circulating fluidized bed, and the reduction of the overall power generation efficiency of a unit and the increase of the running cost caused by higher energy consumption in the air separation oxygen production process and the carbon dioxide capturing process are main obstacles which restrict the large-scale engineering application of the unit.

In addition, in the circulating fluidized bed boiler, after the pure oxygen combustion oxygen concentration is improved, the difficult problem that the oxygen distribution is not matched with the fuel combustion easily occurs, so that the oxygen concentration at the lower part of the combustion chamber of the circulating fluidized bed boiler is too high, local overtemperature is caused, and the efficient and stable operation of the circulating fluidized bed boiler is influenced. The utility model patent CN11094722A discloses an oxygen-enriched combustion system assisted by an oxygen carrier of a fluidized bed and a method thereof, wherein the oxygen carrier is used as a bed material, the combustion of coal is regulated and controlled in a mode of carrying and releasing oxygen by the oxygen carrier, the heat distribution uniformity of a hearth is improved, the stable operation of equipment is ensured, the difficult problem that the oxygen distribution is uneven and difficult to treat under the existing oxygen-enriched combustion of the fluidized bed is solved, the regulation and control of the solid reaction of fuel and the oxygen carrier (metal oxide) at the upper part of the hearth are difficult, and the heating surface is difficult to realize under the pure oxygen combustion working condition.

Disclosure of Invention

The present utility model aims to solve at least one of the technical problems in the related art to some extent.

Therefore, the embodiment of the utility model provides a pure oxygen combustion system with low energy consumption and low cost.

A pure oxygen combustion system according to an embodiment of the present utility model includes: the circulating fluidized bed furnace is a full membrane type water-cooled wall boiler furnace and comprises a feed inlet, a first air inlet and a second air inlet, wherein the first air inlet is communicated with the second air inlet; the first separator is communicated with the first air inlet so that oxygen separated by the first separator is used as primary air to be sent into the hearth, and the first separator is communicated with the second air inlet so that oxygen separated by the first separator is used as secondary air to be sent into the hearth; the fan assembly is communicated with one end of the first separator, and the other end of the fan assembly is respectively communicated with the first air inlet and the second air inlet, so that oxygen separated by the first separator is respectively conveyed to the first air inlet and the second air inlet through the fan assembly; the evaporation heating surface and the superheater are arranged in the hearth, the evaporation heating surface and the superheater are arranged at intervals along the up-down direction, and the evaporation heating surface and the superheater are arranged along the bottom of the hearth.

According to the pure oxygen combustion system provided by the embodiment of the utility model, the evaporation heating surface and the superheater are arranged to solve the problem of local overtemperature caused by overhigh oxygen concentration, and a flue gas recirculation device in the related technology is eliminated, so that the running energy consumption of the pure oxygen combustion system is reduced.

In some embodiments, the pure oxygen combustion system further comprises an air distribution plate arranged at the bottom of the hearth, the distance between the second air inlet and the air distribution plate is L1, the height of the hearth is L2, the ratio between L1 and L2 is 17% -22%, the ratio of the content of primary air in the hearth to the content of secondary air in the hearth is 16% -24%, the average granularity of bed materials of the fluidized bed is less than or equal to 200 μm, the pressure drop of the bed layer of the fluidized bed is 6000Pa-8000Pa, the bed temperature of the fluidized bed is 850 ℃ -900 ℃, and the oxygen content in flue gas at the hearth outlet of the fluidized bed is less than or equal to 4.50%.

In some embodiments, the furnace comprises a third cavity section, a second cavity section and a first cavity section which are sequentially communicated in the up-down direction, wherein in a projection plane orthogonal to the up-down direction, the projection of the third cavity section is positioned in the first cavity section, and the cross-sectional area of the second cavity section is gradually reduced in a direction away from the first cavity section.

In some embodiments, the pure oxygen combustion system further comprises a second separator and a flue, wherein one end of the second separator is communicated with one end of the furnace so that the second separator separates materials in the flue gas flowing out of the furnace, and the flue is communicated with the top of the second separator so that the flue gas separated by the second separator flows into the flue.

In some embodiments, the pure oxygen combustion system further comprises a return and a dipleg, wherein two ends of the dipleg are respectively communicated with the second separator and the return, and the return is communicated with the hearth, so that the materials separated by the second separator flow into the hearth through the dipleg and the return.

In some embodiments, the pure oxygen combustion system further comprises a first economizer and a second economizer, both the first economizer and the second economizer are disposed in the flue, and the first economizer and the second economizer are disposed at intervals along the extending direction of the flue.

In some embodiments, the pure oxygen combustion system further comprises a flue gas compression purification assembly in communication with the flue, the flue gas compression purification assembly adapted to be routed to an oilfield such that carbon dioxide compressed and condensed by the flue gas compression purification assembly is transported to an oilfield flooding, and the superheater is adapted to be routed to the oilfield such that superheated steam exiting the superheater flows into the oilfield for heavy oil thermal recovery.

In some embodiments, the fan assembly includes a first fan, a second fan, a third fan, and a fourth fan, wherein two ends of the first fan are respectively communicated with the first air inlet and the first separator, two ends of the second fan are respectively communicated with the second air inlet and the first separator, two ends of the third fan are respectively communicated with the return and the first separator, and the fourth fan is communicated with the tail of the flue.

In some embodiments, the spacing between the evaporation heating surface and the superheater is 180mm-210mm.

In some embodiments, the pure oxygen combustion system further comprises a fuel silo adapted to store fuel and a feeder in communication with the fuel silo and the furnace, respectively, such that fuel flowing out through the fuel silo flows into the furnace through the feeder.

Drawings

FIG. 1 is a pure oxygen combustion system of an embodiment of the present utility model.

A pure oxygen combustion system 100;

a furnace 1; a first chamber section 11; a second chamber section 12; a third chamber section 13;

a first separator 2; a dipleg 3; a return device 4; a first fan 5; an air distribution plate 6; a second fan 7; a third fan 8; a second separator 9; a fuel bin 10; a feeder 101; an evaporation heating surface 102; a superheater 103; a first economizer 104; a second economizer 105; a fourth fan 106; a flue gas compression purification assembly 107; an oilfield 108; and a flue 109.

Detailed Description

Reference will now be made in detail to embodiments of the present utility model, examples of which are illustrated in the accompanying drawings. The embodiments described below by referring to the drawings are illustrative and intended to explain the present utility model and should not be construed as limiting the utility model.

A pure oxygen combustion system according to an embodiment of the present utility model is described below with reference to the accompanying drawings.

As shown in fig. 1, the pure oxygen combustion system according to the embodiment of the present utility model includes a circulating fluidized bed furnace 1, a first separator 2, a fan assembly, an evaporation heating surface 102, a superheater 103, and an oil field 108.

The circulating fluidized bed furnace 1 is a full membrane type water-cooled wall boiler furnace and comprises a feed inlet, a first air inlet and a second air inlet, wherein the feed inlet, the first air inlet and the second air inlet are all communicated with the furnace 1, the first air inlet is suitable for being filled with primary air, and the second air inlet is suitable for being filled with secondary air. Specifically, as shown in fig. 1, primary air can flow into the hearth through the first air inlet, secondary air can flow into the hearth through the second air inlet, and fuel flows into the hearth through the feed inlet, so that the fuel is fully combusted in the hearth under the action of the primary air and the secondary air.

The first separator 2 is communicated with the first air inlet so that oxygen separated by the first separator 2 is fed into the hearth as primary air, and the first separator 2 is communicated with the second air inlet so that oxygen separated by the first separator 2 is fed into the hearth as secondary air. Specifically, as shown in fig. 1, the first separator 2 is an air separation device, the air separation device can separate oxygen in air, the first separator 2 is provided with a first port and a second port, the first port of the first separator 2 is communicated with the first air inlet through an air pipe, so that pure oxygen separated by the first separator 2 flows into the furnace 1 as primary air, and the second port of the first separator 2 is communicated with the second air inlet through the air pipe, so that pure oxygen separated by the first separator 2 flows into the furnace as secondary air.

One end of the fan assembly is communicated with the first separator 2, and the other end of the fan assembly is respectively communicated with the first air inlet and the second air inlet, so that oxygen separated by the first separator 2 is respectively conveyed to the first air inlet and the second air inlet through the fan assembly. Specifically, the inlet of the fan assembly is communicated with the outlet of the first separator 2, and the outlet of the fan assembly is respectively communicated with the first air inlet and the second air inlet, so that the oxygen separated by the first separator 2 is respectively conveyed to the first air inlet and the second air inlet through the fan assembly.

The evaporation heating surface 102 and the superheater 103 are arranged in the hearth 1, the evaporation heating surface 102 and the superheater 103 are arranged at intervals along the up-down direction, and the evaporation heating surface 102 and the superheater 103 are arranged along the bottom adjacent to the hearth 1. Specifically, as shown in fig. 1, the evaporation heating surface 102 is a buried pipe evaporation heating surface, the superheater 103 is a buried pipe superheater, the evaporation heating surface 102 and the superheater 103 are both disposed inside the furnace 1 and are disposed near the bottom of the furnace 1, the evaporation heating surface 102 and the superheater 103 are disposed at intervals along the up-down direction, and the positions of the evaporation heating surface 102 and the superheater 103 may be set according to practical situations, 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, and the like, so that when pure oxygen burns, the bottom of the hearth 1 has too high oxygen content and the top has lower oxygen content, so that the bottom of the hearth 1 burns severely and the temperature is higher, and therefore, the evaporation heating surface 102 and the superheater 103 are arranged along the bottom of the adjacent hearth 1, and the problem of local overtemperature caused by the too high oxygen concentration at the lower part of the hearth 1 is solved.

In the pure oxygen combustion system 100 according to the embodiment of the utility model, because the flue gas generated by the pure oxygen combustion is too small (the nitrogen content in the flue gas of the pure oxygen combustion is very small), the heat taken away by the flue gas flowing out of the hearth is too small, and in the related art, the superheater is arranged in the flue. Therefore, the flue gas flowing out of the hearth is difficult to heat the working medium in the superheater in the related technology into superheated steam in the flue. Therefore, the superheater 103 is arranged inside the hearth and near the bottom of the hearth 1 to ensure that the steam in the superheater 103 is heated, and in addition, the temperature in the pure oxygen combustion hearth is higher, so that the evaporation heating surface 102 is arranged in the hearth 1 and the evaporation heating surface 102 is arranged along the position adjacent to the bottom of the hearth 1, and the problem of local overtemperature caused by the overhigh oxygen concentration in the hearth 1 can be solved.

Because the pure oxygen combustion circulating fluidized bed furnace 1 increases along with the increase of the oxygen concentration, the combustion rate is increased, the smoke quantity is greatly reduced, a series of changes such as gas-solid flow, combustion reaction, heat and mass transfer are caused, and the like, the particle size of finer bed materials and the particle size of coal feeding can still maintain the flow state of the rapid bed at the upper part of the furnace under the condition that the smoke quantity of the pure oxygen combustion is small, therefore, in some embodiments, the average particle size of the bed materials of the fluidized bed is less than or equal to 200 mu m, and the average particle size of the fuel in the fluidized bed is less than or equal to 1mm. Thereby, the circulating fluidized bed can be fluidized rapidly.

Because of the severe combustion of pure oxygen, the lower part of the furnace 1 is easily overheated, and the heat needs to be brought to the upper part of the furnace 1 by means of enough circulating materials, so that the temperature distribution in the furnace is ensured to be uniform, and therefore, in some embodiments, the bed pressure drop of the fluidized bed is 6000Pa-8000Pa. Thus, a bed pressure of 6000Pa-8000Pa is ensured and an average pressure drop in the upper part of the furnace 1 is defined, whereby a sufficient uniform distribution of circulating material and temperature can be ensured.

The furnace 1 has a higher temperature under pure oxygen combustion conditions, but the too high temperature is disadvantageous for low nitrogen emission. Thus, in some embodiments, the bed temperature of the fluidized bed is 850 ℃ to 900 ℃. Combustion and NOx emissions can thus be controlled, reducing NOx emissions.

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 is too high, so that the temperature in the furnace 1 is high, and the stable and efficient operation of the circulating fluidized bed is affected, 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%. Thereby being beneficial to controlling the combustion temperature in the hearth 1 and ensuring the stable and efficient operation of the circulating fluidized bed.

Since the problem of overheating of the lower part of the furnace caused by pure oxygen combustion is solved by considering that the buried pipe evaporation heating surface 102 is arranged, in order to reduce the abrasion of buried pipes, and the normal fluidization of the coal fuel after ash formation abrasion is considered, the fluidization speed of the bottom of the furnace 1 of the fluidized bed is 0.8m/s-1.6m/s in some embodiments. Specifically, the fluidization velocity of the fluidized bed may be any of 0.8m/s, 1.0m/s, 1.2m/s, 1.4m/s, 1.6m/s, etc., and when the fluidization velocity is less than 0.8m/s, it will cause too low a fluidization velocity, so that the fluidized bed cannot normally fluidize, and when the fluidization velocity is greater than 1.6m/s, it will cause too high a fluidization velocity, and will cause wear to the buried pipe evaporation heating surface 102 and the buried pipe superheater 103.

It will be appreciated that the cross-sectional area of the bottom of the furnace and the transverse rows of burial pipes can be controlled so that the fluidization velocity at the bottom of the furnace 1 is in the range of 0.8-1.6m/s.

In order to reduce the generation of NOx, the hearth 1 adopts a staged combustion mode, meanwhile, the problem of fluidization of bed materials at the lower part of the hearth is considered, the pure oxygen combustion system 100 further comprises an air distribution plate 6 arranged at the bottom of the hearth 1 according to engineering experience, the distance between the second air inlet and the air distribution plate 6 is L1, the height of the hearth is L2, the ratio between the L1 and the L2 is 17% -22%, and the ratio of the content of primary air in the hearth 1 to the content of secondary air in the hearth 1 is 16% -24%. Thereby the structural arrangement of the hearth 1 is more reasonable.

In some embodiments, the furnace 1 comprises a third cavity section 13, a second cavity section 12 and a first cavity section 11 which are sequentially communicated in the up-down direction, an air distribution plate is arranged at the lower end of the first cavity section 11, in a projection plane orthogonal to the up-down direction, the projection of the third cavity section 13 is positioned in the first cavity section 11, and the cross-sectional area of the second cavity section 12 is gradually reduced in a direction away from the first cavity section 11. Specifically, as shown in fig. 1, the first cavity section 11 is a dense phase zone, the third cavity section 13 is a dilute phase zone, the second cavity section 12 is a transition zone, the second cavity section 12 is arranged above the first cavity section 11, the third cavity section 13 is arranged above the second cavity section 12, the cross-sectional area of the first cavity section 11 is larger than that of the third cavity section 13, and the cross-sectional area of the second cavity section 12 is gradually increased from top to bottom, so that the flow rate of flue gas of the third cavity section 13 is larger than that of flue gas of the first cavity section 11, and the third cavity section 13 can achieve rapid fluidization.

In some embodiments, the flue gas velocity in the upper part of the furnace 1 of the fluidized bed is 2.06m/s-2.48m/s. In particular, the flue gas velocity of the third chamber section 13 may be any of 2.06m/s, 2.16m/s, 2.26m/s, 2.36m/s, 2.48m/s etc., since the amount of flue gas is constant, the flue gas fluidization velocity is limited in order to meet a fast fluidization in the upper dilute phase zone of the furnace.

In some embodiments, the pure oxygen combustion system 100 further comprises a second separator 9 and a flue 109, wherein one end of the second separator 9 is in communication with one end of the furnace 1 so that the second separator 9 separates materials in the flue gas flowing out of the furnace, and the flue 109 is in communication with the top of the second separator 9 so that the flue gas separated by the second separator 9 flows into the flue 109. Specifically, as shown in fig. 1, the second separator 9 is a cyclone separator, an inlet of the second separator 9 is communicated with a furnace outlet, and flue gas flowing out of the furnace 1 can flow into the cyclone separator, so that materials (bed materials and fuel) in the flue gas are separated by the cyclone separator, and the separated flue gas flows into the flue 109.

In some embodiments, the pure oxygen combustion system 100 further comprises a dipleg 3 and a return 4, both ends of the dipleg 3 being in communication with the second separator 9 and the return 4, respectively, the return 4 being in communication with the furnace 1 such that the material separated by the second separator 9 flows into the furnace 1 through the dipleg 3 and the return 4. Specifically, as shown in fig. 1, the dipleg 3 extends in the up-down direction, and the inlet of the dipleg 3 is communicated with the outlet of the second separator 9, the outlet of the dipleg 3 is communicated with the inlet of the return feeder 4, and the outlet of the return feeder 4 is communicated with the hearth 1, so that the materials separated by the second separator 9 are returned to the hearth 1 through the dipleg 3 and the return feeder 4, thereby improving the utilization rate of the materials and regulating the load of the boiler.

It can be understood that the diplegs 3 can enable the material particles to flow smoothly from top to bottom, so that the material can flow into the hearth 1 smoothly.

In some embodiments, the pure oxygen combustion system 100 further includes a first economizer 104 and a second economizer 105, the first economizer 104 and the second economizer 105 being disposed within the flue 109, the first economizer 104 and the second economizer 105 being disposed at intervals along the direction of extension of the flue 109. Specifically, as shown in fig. 1, 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 practical situations, in other words, one or more first economizers 104 and the plurality of second economizers 105 can be set, and 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 heat of flue gas in the flue 109, the exhaust gas temperature of the flue gas is reduced, and the thermal efficiency of the boiler system is improved.

It should be noted that, the flue gas temperature at the outlet of the circulating fluidized bed furnace 1 is low, the flue gas amount generated by pure oxygen combustion is small, that is, the heat taken away by the flue gas leaving the furnace is small, and even the preheating of working medium cannot be satisfied, the heat transfer amount share in the pure oxygen combustion main circulation loop is large, and the economizer is generally arranged in the tail flue, if the superheater 103 is arranged in the tail flue, the saturated steam in the superheater 103 is difficult to be heated into superheated steam by the heat taken away by the flue gas, and in addition, insufficient heat is used for preheating water in the first economizer 104 and the second economizer 105, and the superheater 103 is arranged in the furnace 1 to absorb heat according to the distribution of the heat absorption and the heat release.

In some embodiments, the pure oxygen fired boiler system 100 further comprises a flue gas compression purification assembly 107, the flue gas compression purification assembly 107 is arranged at the tail of the flue 109, the flue gas compression purification assembly 107 is suitable for being led to an oil field 108, so that carbon dioxide obtained by compression condensation of the flue gas compression purification assembly 107 is transported to the oil field 108 for displacement of oil, and the superheater 103 is suitable for being led to the oil field 108, so that superheated steam flowing out of the superheater 103 flows into the oil field 108 for thickened oil thermal recovery. Specifically, as shown in fig. 1, the flue gas compression and purification assembly 107 is a flue gas compression and purification device, and an inlet of the flue gas compression and purification device is communicated with an outlet of the flue 109, so that flue gas flowing out of the flue 109 is compressed and condensed by the flue gas compression and purification device to obtain high-purity carbon dioxide, the high-purity carbon dioxide is conveyed to the oil field 108 for enhanced oil recovery, and steam generated by heating of the superheater 103 can also be conveyed into the oil field 108 for thickened oil thermal recovery of the oil field 108, so that the utilization rate of the carbon dioxide is improved.

In some embodiments, the spacing between the evaporation heating surface 102 and the superheater 103 is 180mm-210mm. Specifically, the space between the evaporation heating surface 102 and the superheater 103 can be any one of 180mm, 190mm, 200mm and 210mm, and the space between the evaporation heating surface 102 and the superheater 103 is 180-210 mm, so that the arrangement of the evaporation heating surface 102 and the superheater 103 is more reasonable, and the problem of heat distribution of the pure oxygen combustion circulating fluidized bed can be solved.

Preferably, the evaporation heating surface 102 is disposed at a position 0.5m higher than the bottom air distribution plate, leaving a maintenance space. The buried pipe superheater is a coiled pipe and is arranged at a position 0.2m higher than the evaporation heating surface of the buried pipe, and the buried pipes in the evaporation heating surface 102 and the superheater 103 are front and rear wall inlet and outlet pipes.

In some embodiments, the pure oxygen combustion system 100 further comprises a fuel silo 10 and a feeder 101, the fuel silo 10 being adapted to store fuel, the feeder 101 being in communication with the fuel silo 10 and the furnace 1, respectively, such that fuel flowing out through the fuel silo 10 flows into the furnace 1 through the feeder 101. Specifically, as shown in fig. 1, the inlet of the feeder 101 communicates with the outlet of the fuel tank 10, and the outlet of the feeder 101 communicates with the feed port of the furnace 1, whereby fuel is fed to the furnace 1 through the fuel tank 10 and the feeder 101.

It is to be understood that the feeder 101 may be a belt conveyor, a chain conveyor, or the like, and the present utility model is not particularly limited.

In some embodiments, the fan assembly includes a first fan 5, a second fan 7, a third fan 8, and a fourth fan 106.

Both ends of the first fan 5 are respectively communicated with the first air inlet and the first separator 2. Specifically, as shown in fig. 1, the first fan 5 is a primary fan, the inlet of the first fan 5 is communicated with the outlet of the first separator 2, and the outlet of the first fan 5 is communicated with the first air inlet of the furnace 1, so that pure oxygen is conveyed to the furnace 1 through the first fan 5 as primary air and is conveyed into the furnace 1.

Two ends of the second fan 7 are respectively communicated with the second air inlet and the first separator 2. Specifically, as shown in fig. 1, the second fan 7 is a secondary fan, the inlet of the second fan 7 is communicated with the outlet of the first separator 2, and the outlet of the second fan 7 is communicated with the second air inlet of the furnace 1, so that pure oxygen is conveyed to the furnace 1 through the second fan 7 to be conveyed into the furnace 1 as secondary air.

Both ends of the third fan 8 are respectively communicated with the material returning device 4 and the first separator 2. Specifically, as shown in fig. 1, the third fan 8 is a high-pressure roots fan, the inlet of the third fan 8 is communicated with the outlet of the first separator 2, and the outlet of the third fan 8 is communicated with the material returning device 4, so that high-pressure air (loose air and air-conveying air) is provided through the third fan 8, and normal material returning and material returning quantity control are ensured.

The fourth fan 106 communicates with the flue 109. Specifically, as shown in fig. 1, the fourth fan 106 is an induced draft fan, so that the flue gas in the flue 109 is pumped into the flue gas compression and purification assembly 107 by the fourth fan 106.

It is worth noting that, due to the change of the combustion mode (pure oxygen combustion), the main components of the flue gas are three-atomic gas carbon dioxide and water (different from diatomic gas nitrogen in air which is the main component), which results in the flue gas generated in the pure oxygen combustion mode having stronger radiation heat exchange characteristics and higher heat capacity. And fitting physical parameters of each component of the smoke in a pure oxygen combustion mode, and improving a heat transfer calculation method in a mode of mixing the components first.

In some embodiments, the primary and secondary air content in the furnace is 8:2. therefore, the bottom of the hearth can be guaranteed to be normally fluidized, and the generation problem of nitrogen oxides is reduced.

It will be appreciated that the air preheater in the circulating fluidized bed is designed to reduce the exhaust gas temperature and increase the thermal efficiency of the boiler, and that the thermal efficiency of the pure oxygen combustion boiler is already high enough, and calculations indicate that the thermal efficiency of the boiler is reduced by 1% every 65 ℃. Next, there is a risk of leakage of oxygen during preheating, so that no air preheater is provided in the back pass 109.

The pure oxygen combustion system 100 of an embodiment of the present utility model is specifically described below.

The technology is used for designing a 130t/h pure oxygen combustion circulating fluidized bed (rated steam pressure 13.7MPa and rated steam temperature 420 ℃). The circulating fluidized bed is used for burning and enlarging the soft coal, the low-order heating value is 20000kJ/kg, and the industrial analysis data comprise 18.00% of water (Ma), 21.00% of ash (Aa) and 41.00% of volatile (Va); elemental analysis data were 50.28% carbon (Cdaf), 3.68% hydrogen (Hdaf), 0.96% nitrogen (Ndaf), 0.48% sulfur (Sdaf), and 5.60% oxygen (Odaf).

Under the rated working condition, the average granularity of the bed material is 150 mu m; the bed pressure drop is 7000Pa; the bed temperature is controlled at 885 ℃; the oxygen content of the flue gas at the outlet of the hearth is controlled to be 4 percent. The ratio of the primary air quantity to the secondary air quantity is regulated to be 8:2; setting the smoke discharging temperature to be 150 ℃ and the water feeding temperature to be 104 ℃; the heat efficiency of the boiler can reach up to 95.01% in a pure oxygen combustion mode; the fuel consumption was 5.02kg/s. The cross section area of the lower part of the hearth 1 is set to be 24.19 square meters, and the width-to-depth ratio is 2:1, so that the fluidization speed of the empty tower can reach 0.83m/s. The width of the upper part of the hearth 1 is unchanged, the depth is reduced to 2.05m, and the fluidization speed of the flue gas can reach 2.47m/s, thereby meeting the requirement of rapid fluidization.

The total height of the hearth is 16m, the buried pipe evaporation heating surface 102 with phi 76 multiplied by 14mm is paved on the front wall outlet pipe and the rear wall outlet pipe with the height of 0.5m above the air distribution plate 6, the number of transverse and longitudinal pipe rows is 36 and 7 respectively, and the transverse and longitudinal relative pitches are 2.11 and 1.45 respectively. Three buried pipe superheaters 103 with phi 70 multiplied by 10mm are paved in three groups at a height of 0.2m above the buried pipe evaporation heating surface 102, the number of transverse and longitudinal pipe rows is 31 and 3 respectively, and the transverse and longitudinal relative pitches are 2.29 and 2.86 respectively.

The first economizers 104 are arranged at the upper part of the tail flue 109 (4.50mX1.00 m), and are arranged in parallel and counter-current, and each row of the tube bundles is formed by two phi 32X 5mm tubes, the number of transverse and longitudinal tube rows of each group of the first economizers 104 is 46 and 14 respectively, the transverse and longitudinal relative pitches are 3.00 and 1.88 respectively, and the spacing between the tube groups is 0.86m. The second economizer 105 was arranged at the lower part of the tail flue 109, and consisted of 5 horizontal tube groups arranged in series and counter-current, each tube group was likewise wound from two phi 32 x 5mm tubes, the number of transverse and longitudinal tube rows of each group of the second economizer 105 was 57 and 22, respectively, the transverse and longitudinal relative pitches were 2.44 and 1.88, respectively, and the tube group spacing was 0.86m. The heat distribution of the whole 130t/h pure oxygen combustion circulating fluidized bed furnace 1 with brand new design is reasonable, and the heat absorption error of working media is controlled to be 0.0014%.

In the description of the present utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present utility model and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present utility model.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present utility model, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.

In the present utility model, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present utility model, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

In the present disclosure, the terms "one embodiment," "some embodiments," "examples," "specific examples," "some examples," and the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

While embodiments of the present utility model have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the utility model, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the utility model.

Claims (10)

1. A pure oxygen combustion system, comprising: the circulating fluidized bed furnace is a full membrane type water-cooled wall boiler furnace and comprises a feed inlet, a first air inlet and a second air inlet, wherein the first air inlet is communicated with the second air inlet; the first separator is communicated with the first air inlet so that oxygen separated by the first separator is used as primary air to be sent into the hearth, and the first separator is communicated with the second air inlet so that oxygen separated by the first separator is used as secondary air to be sent into the hearth; the fan assembly is communicated with one end of the first separator, and the other end of the fan assembly is respectively communicated with the first air inlet and the second air inlet, so that oxygen separated by the first separator is respectively conveyed to the first air inlet and the second air inlet through the fan assembly; the evaporation heating surface and the superheater are arranged in the hearth, the evaporation heating surface and the superheater are arranged at intervals along the up-down direction, and the evaporation heating surface and the superheater are arranged along the bottom of the hearth.

2. The pure oxygen combustion system according to claim 1, further comprising an air distribution plate arranged at the bottom of the furnace, wherein the distance between the second air inlet and the air distribution plate is L1, the height of the furnace is L2, the ratio between L1 and L2 is 17% -22%, the ratio of the content of primary air in the furnace to the content of secondary air in the furnace is 16% -24%,

the average granularity of the bed material of the fluidized bed is less than or equal to 200 mu m, the pressure drop of the bed layer of the fluidized bed is 6000Pa-8000Pa, the bed temperature of the fluidized bed is 850-900 ℃, and the oxygen content in flue gas at the outlet of a hearth of the fluidized bed is less than or equal to 4.50%.

3. The pure oxygen combustion system of claim 1, wherein the furnace comprises a third chamber section, a second chamber section, and a first chamber section that are sequentially communicated in an up-down direction, wherein a projection of the third chamber section is located in the first chamber section in a projection plane orthogonal to the up-down direction, and a cross-sectional area of the second chamber section gradually decreases in a direction away from the first chamber section.

4. The pure oxygen combustion system of claim 1, further comprising a second separator and a flue, wherein one end of the second separator is in communication with one end of the furnace so that the second separator separates material in the flue gas flowing out of the furnace, and wherein the flue is in communication with a top of the second separator so that the flue gas separated by the second separator flows into the flue.

5. The pure oxygen combustion system of claim 4, further comprising a return and a dipleg, wherein two ends of the dipleg are respectively in communication with the second separator and the return, and wherein the return is in communication with the furnace such that material separated by the second separator flows into the furnace through the dipleg and the return.

6. The pure oxygen combustion system of claim 4, further comprising a first economizer and a second economizer, wherein the first economizer and the second economizer are both disposed within the flue, and wherein the first economizer and the second economizer are spaced apart along the direction of extension of the flue.

7. The pure oxygen combustion system of claim 4, further comprising a flue gas compression purification assembly in communication with the flue, the flue gas compression purification assembly adapted to be routed to an oilfield such that carbon dioxide compressed and condensed by the flue gas compression purification assembly is transported to an oilfield flooding, the superheater adapted to be routed to the oilfield such that superheated steam exiting the superheater flows into the oilfield for thickened oil thermal recovery.

8. The pure oxygen combustion system of claim 5, wherein the fan assembly comprises a first fan, a second fan, a third fan and a fourth fan, wherein two ends of the first fan are respectively communicated with the first air inlet and the first separator, two ends of the second fan are respectively communicated with the second air inlet and the first separator, two ends of the third fan are respectively communicated with the material returning device and the first separator, and the fourth fan is communicated with the tail of the flue.

9. A pure oxygen combustion system according to any of claims 1-8, wherein the spacing between the evaporation heating surface and the superheater is 180mm-210mm.

10. The pure oxygen combustion system of any of claims 1-8, further comprising a fuel silo and a feeder, the fuel silo being adapted to store fuel, the feeder being in communication with the fuel silo and the furnace, respectively, such that fuel flowing out through the fuel silo flows into the furnace through the feeder.