Hydrogen and steam oxygen-enriched flameless combustor
Technical Field
The invention belongs to the field of flameless combustors, and particularly relates to a hydrogen steam oxygen-enriched flameless combustor.
Background
In recent years, with the rapid consumption of fossil energy by human beings, environmental problems have become serious, in which nitrogen oxides generated by the combustion of fossil energy are one of the main causes of the formation of acid rain and PM2.5, and CO generated by the combustion of fossil fuel is simultaneously generated2But also aggravates greenhouse gas effect and has great influence on the environment. Hydrogen is a new fuel and is of great interest because of its many advantages, for example, hydrogen has a high calorific value and thus generates high energy when it is burned; the product after hydrogen combustion is only water, so the hydrogen combustion has the characteristics of cleanness and no pollution; in addition, the hydrogen can be obtained directly from water and can be recycled. However, hydrogen combustion also has drawbacks that are difficult to overcome: the calorific value of hydrogen is high, and the corresponding combustion temperature is high, so that the emission of nitrogen oxides (NOx) accompanied with the combustion of hydrogen is also high; the combustion rate of hydrogen is extremely fast and the hydrogen is extremely easy to explode, so the potential safety hazard of hydrogen combustion also limits the large-scale use of hydrogen.
In addition, a new combustion technology is also another way for reducing pollutant emission, and oxygen-enriched combustion and flameless combustion are continuously concerned in recent years, in the traditional oxygen-enriched combustion, carbon dioxide replaces nitrogen to dilute oxygen, so that a large amount of carbon dioxide is contained in flue gas, capture and storage of the carbon dioxide are facilitated, and meanwhile, the carbon dioxide has higher heat capacity relative to the nitrogen, so that the combustion temperature is relatively low, and further the emission of NOx is reduced to a certain extent. Flameless combustion as an emerging technology has the following advantages: low reaction rate, less local heat release, uniform heat flow distribution, low combustion temperature, uniform distribution, no flame front, low noise and extremely low NOx emission. The technology combining oxygen-enriched combustion and flameless combustion is called oxygen-enriched flameless combustion technology, and combines the advantages of oxygen-enriched combustion and flameless combustion, so that the emission of nitrogen oxides can be reduced to a greater extent.
At present, the research on the flameless combustion technology is greatly advanced, for example, CN201310624080.3 proposes a method and a system for oxygen-enriched flameless combustion of coal powder, the invention improves the stability, the burnout rate and the radiation heat exchange of the flameless combustion on the basis of enriching carbon dioxide by the oxygen-enriched combustion; CN201410528106.9 proposes an oxygen-enriched gas flameless burner, which can organically combine flameless combustion and oxygen-enriched combustion, realize flameless combustion, optimize the temperature distribution in the furnace and reduce NOx emission. However, the existing oxygen-enriched combustors use carbon dioxide as an oxidant diluent, and high-purity steam flue gas can be obtained by using steam as a diluent for hydrogen fuel, so that the generation of NOx is reduced and the flue gas is favorably captured; meanwhile, for fuel with extremely fast burning rate, such as hydrogen, no patent is invented for relevant flameless burner at present, which limits the utilization of clean energy, such as hydrogen.
Disclosure of Invention
In order to overcome the defects or the improvement requirements in the prior art, the invention provides the hydrogen steam oxygen-enriched flameless combustor, wherein the characteristics of oxygen-enriched combustion and flameless combustion are combined, the structures and the specific arrangement modes of key components of the hydrogen steam oxygen-enriched flameless combustor, such as the first steam spray pipe, the primary air spray pipe and the secondary air spray pipe, are researched and designed, the oxygen-enriched flameless combustion of hydrogen can be correspondingly realized, the problem of generating a large amount of nitrogen oxides in the fuel combustion process is effectively solved, and the water capture of flue gas can be directly realized, so that the hydrogen steam oxygen-enriched flameless combustor is particularly suitable for the application occasions of hydrogen.
In order to achieve the purpose, the invention provides a hydrogen steam oxygen-enriched flameless combustor, which comprises a hydrogen spray pipe, a first steam spray pipe, a primary air spray pipe, a secondary air spray pipe, a first heat-preservation pipeline, a second heat-preservation pipeline and a combustion chamber, wherein:
the hydrogen spray pipe is connected with the combustion chamber and is used for spraying hydrogen to the combustion chamber;
the first steam spray pipe is sleeved on the outer side of the hydrogen spray pipe, is connected with the combustion chamber and is used for spraying steam to the combustion chamber in a preheating stage so as to reduce the combustion rate of the hydrogen; the primary air spray pipe is sleeved on the outer side of the first steam spray pipe, is connected with the combustion chamber and is used for spraying mixed gas of steam and oxygen to the combustion chamber as primary air in a preheating stage so as to provide oxygen for oxygen-enriched flame combustion of the hydrogen; meanwhile, the outlets of the first steam spray pipe and the primary air spray pipe are respectively and uniformly provided with a first rotational flow blade and a second rotational flow blade along the circumferential direction, and the first rotational flow blades and the second rotational flow blades are used for driving the steam and the primary air to rotate along the axis of the hydrogen spray pipe with the same rotational flow degree;
the secondary air spray pipe is connected with the combustion chamber and used for spraying mixed gas of water vapor and oxygen to the combustion chamber as secondary air in a flameless combustion stage so as to provide oxygen for oxygen-enriched flameless combustion of the hydrogen;
the first heat-preservation pipeline is sleeved outside the hydrogen spray pipe, the first steam spray pipe and the primary air spray pipe and used for preheating the hydrogen, the steam and the primary air and avoiding the steam from condensing; the second heat-insulation pipeline is sleeved on the outer side of the secondary air spray pipe and used for preheating the secondary air;
the combustion chamber is used for providing space for oxygen-enriched combustion of the hydrogen.
Preferably, the inlet of the hydrogen nozzle is provided with a tempering-proof cavity for stabilizing the inlet pressure of the hydrogen, so as to ensure the safety of the combustion process, and the number of the tempering-proof cavities is 1-3.
Preferably, the hydrogen-water-steam oxygen-enriched flameless combustor further comprises a second water steam pipeline, and the second water steam pipeline is connected with the secondary air spray pipe and is used for introducing water steam in flue gas into the secondary air so as to dilute the concentration of oxygen in the secondary air.
Preferably, the flue gas generated by combustion is introduced into the first heat-insulating pipeline and the second heat-insulating pipeline, so that the waste heat of the flue gas is recycled.
More preferably, the degree of swirl of the water vapor and the primary air is preferably 0.7 to 0.9.
More preferably, the diameter of the primary air nozzle is 1.5 to 3 times of the diameter of the hydrogen nozzle, and the diameter of the secondary air nozzle is 1 to 5 times of the diameter of the hydrogen nozzle.
More preferably, the concentration of oxygen in the primary air and the secondary air is preferably 10% to 50%, and the concentration of oxygen in the combustion chamber in the flameless combustion stage is preferably 2% to 10%.
Further preferably, a water injection temperature reduction pipe is arranged in the combustion chamber and used for injecting water into the combustion chamber so as to reduce the temperature of the local high-temperature area.
As a further preferred option, the hydrogen water vapor oxygen-enriched flameless combustor further comprises a blunt body arranged in the combustion chamber, a cooling water pipeline is arranged in the blunt body and used for reducing the temperature of the blunt body, the blunt body is located at the outlet of the hydrogen gas spray pipe and used for forming stable flame, and in the flameless combustion stage, the blunt body is tightly attached to the inner wall of the combustion chamber, so that flameless combustion is realized.
Preferably, the outlet of the secondary air spray pipe is provided with 1-5 nozzles, and the outlet flow speed of the secondary air spray pipe is adjusted by changing the number of the nozzles.
Generally, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:
1. according to the invention, the first steam spray pipe and the primary air spray pipe are sequentially sleeved outside the hydrogen spray pipe, the flame combustion of hydrogen can be realized in the preheating stage, meanwhile, the primary air is separated from the hydrogen by using steam, the combustion rate of the hydrogen can be effectively reduced, and thus, the safety of the combustor is improved, after the preset temperature is reached, the secondary air spray pipe is switched to provide oxygen to realize the flameless combustion of the hydrogen, the temperature distribution in the combustor can be ensured to be more uniform, and thus, the potential safety hazard generated by the combustion of the hydrogen is avoided;
2. particularly, the diameters of the primary air spray pipe and the secondary air spray pipe are optimized, so that the safety of flame combustion and the uniformity of flameless combustion can be ensured;
3. meanwhile, aiming at the characteristics that the combustion rate of the hydrogen is too high and the hydrogen is easy to explode, the combustion rate of the hydrogen can be effectively controlled by controlling the concentration of oxygen in the primary air and the secondary air and optimizing the concentration of the oxygen in the combustion chamber, meanwhile, the inlet of the hydrogen spray pipe is provided with the tempering-proof cavity, the air inlet pressure of the hydrogen can be stabilized, and the explosion caused by tempering is avoided.
Drawings
FIG. 1 is a cross-sectional view of a hydrogen steam oxygen-rich flameless combustor constructed in accordance with a preferred embodiment of the present invention;
3 FIG. 32 3 is 3 a 3 cross 3- 3 sectional 3 view 3 taken 3 along 3 the 3 line 3 A 3- 3 A 3 in 3 FIG. 31 3; 3
FIG. 3 is a schematic view of a combustion system constructed using the hydrogen-steam oxygen-enriched flameless combustor provided by the present invention.
The same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein:
1-a hydrogen nozzle, 2-a primary air nozzle, 3-a secondary air nozzle, 4-a first heat preservation pipeline, 5-a first steam nozzle, 6-a bluff body, 7-a first swirl blade, 7' -a second swirl blade, 8-a water spray temperature reduction pipe, 9-a second heat preservation pipeline, 10-a second steam nozzle, 11-a combustion chamber, 12-an anti-backfire cavity, 13-a hydrogen steam oxygen-enriched flameless combustor, 14-an oxygen flowmeter, 15-an oxygen cylinder, 16-a hydrogen flowmeter, 17-a hydrogen cylinder, 18-a third booster fan, 19-a first booster fan, 20-a water catching tank, 21-a hydrogen pipeline, 22-a first oxygen inlet pipeline, 23-a secondary air inlet pipeline, 24-a first steam inlet pipeline, 25-a third steam inlet pipeline, 26-a second steam inlet pipeline, 27-a flue gas circulating pipeline, 28-a primary air inlet pipeline, 29-a second flue gas inlet pipeline, 30-a flue gas pipeline, 31-a water catching pipeline and 32-a second booster fan.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
As shown in fig. 1-2, a preferred embodiment of the present invention provides a hydrogen-water-steam oxygen-enriched flameless combustor, which includes a hydrogen nozzle 1, a first water-steam nozzle 5, a primary air nozzle 2, a secondary air nozzle 3, a second water-steam pipeline 10, a first heat-preservation pipeline 4, a second heat-preservation pipeline 9 and a combustion chamber 11, wherein:
the hydrogen spray pipe 1 is connected with the combustion chamber 11 and used for spraying hydrogen to the combustion chamber 11, the inlet of the hydrogen spray pipe 1 is provided with a tempering-proof cavity 12 which is used for stabilizing the air inlet pressure of the hydrogen and preventing the tempering phenomenon from occurring, so that the safety of the combustion process is ensured, and the number of the tempering-proof cavities 12 is 1-3;
the first steam spray pipe 5 is sleeved on the outer side of the hydrogen spray pipe 1, is connected with the combustion chamber 11 and is used for spraying steam to the combustion chamber 11 in a preheating stage so as to reduce the combustion rate of hydrogen, and first swirl blades 7 are uniformly arranged on the outlet of the first steam spray pipe 5 along the circumferential direction and are used for driving the steam to rotate along the axis of the hydrogen spray pipe 1;
the primary air spray pipe 2 is sleeved on the outer side of the first water vapor spray pipe 5, is connected with the combustion chamber 11 and is used for spraying mixed gas of water vapor and oxygen to the combustion chamber 11 as primary air in a preheating stage so as to provide oxygen for oxygen-enriched flame combustion of hydrogen, and second swirl vanes 7' are uniformly arranged at the outlet of the primary air spray pipe 2 along the circumferential direction and are used for driving the primary air to rotate along the axis of the hydrogen spray pipe 1 so as to generate swirl flame in the preheating stage so as to preheat the combustion chamber 11;
the secondary air spray pipe 3 is connected with the combustion chamber 11 and used for spraying mixed gas of water vapor and oxygen to the combustion chamber 11 as secondary air in a flameless combustion stage so as to provide oxygen for oxygen-enriched flameless combustion of hydrogen, the outlet of the secondary air spray pipe 3 is provided with 1-5 nozzles, the outlet flow rate of the secondary air spray pipe 3 is adjusted by changing the number of the nozzles, and FIG. 2 is a distribution schematic diagram of 5 nozzles;
the second steam pipeline 10 is connected with the secondary air spray pipe 3 and is used for introducing steam in the flue gas into secondary air so as to dilute the concentration of oxygen in the secondary air;
the first heat preservation pipeline 4 is sleeved on the outer sides of the hydrogen spray pipe 1, the first steam spray pipe 5 and the primary air spray pipe 2 and used for preheating hydrogen, steam and primary air and avoiding condensation of the steam at the same time, the second heat preservation pipeline 9 is sleeved on the outer sides of the secondary air spray pipe 3 and the second steam spray pipe 10 and used for preheating secondary air and the steam and avoiding condensation of the steam at the same time, and flue gas generated by combustion is introduced into the first heat preservation pipeline and the second heat preservation pipeline, so that waste heat recycling of the flue gas is realized;
the combustion chamber 11 provides a space for oxygen-enriched combustion of hydrogen, and a water spraying temperature-reducing pipe 8 is arranged in the combustion chamber 11 and used for spraying water into the combustion chamber 11, so that the temperature of a local high-temperature area is reduced, and the generation of NOx in the hydrogen combustion process is reduced.
Further, vapor and primary air rotate along the axis of hydrogen spray pipe with the same whirl degree, can postpone the mixture of hydrogen and oxygen to realize the clean medium temperature burning of hydrogen, vapor and primary air's whirl degree is preferred 0.7 ~ 0.9 simultaneously, can produce the whirl in the stage of preheating and have the flame to burn, preheat in order carrying out the combustion chamber, can also postpone the mixture of hydrogen and oxygen simultaneously, reduce combustion rate and flame temperature.
Further, the diameter of the primary air spray pipe 2 is 1.5-3 times of that of the hydrogen spray pipe 1, so that the primary air inlet speed is close to the hydrogen inlet speed, and the primary air inlet speed and the hydrogen are fully mixed after entering the combustion chamber to realize swirl combustion; the diameter of the secondary air spray pipe 3 is 1-5 times of that of the hydrogen spray pipe 1, and meanwhile, the oxidant in the secondary air can be fully diluted by water vapor and the speed of the oxidant can reach 50-150 m/s, so that a large amount of smoke can be sucked after the secondary air enters a combustion chamber, and oxygen-enriched flameless combustion of the water vapor can be realized.
In order to reduce the combustion rate of hydrogen and improve the safety of the burner, the concentration of oxygen in the primary air and the secondary air is preferably 10% -50%, and the concentration of oxygen in the combustion chamber 11 is preferably 2% -10% in the flameless combustion stage, so that a uniform low-oxygen atmosphere can be achieved in the combustion chamber in the flameless combustion stage, and the oxygen-enriched flameless combustion of water vapor can be conveniently realized.
Further, hydrogen vapor oxygen boosting flameless combustor is still including setting up bluff body 6 in combustion chamber 11, and because of hydrogen combustion temperature is higher, the inside of bluff body 6 is provided with cooling water piping to reduce its temperature, preheat the stage, bluff body 6 is located the export of hydrogen spray tube 1 for form stable flame, flameless combustion stage, bluff body 6 pastes tight combustion chamber 11 inner wall, thereby realize flameless combustion.
The combustion system constructed by the hydrogen water vapor oxygen-enriched flameless combustor provided by the invention is shown in figure 3, wherein a hydrogen nozzle 1 of a hydrogen water vapor oxygen-enriched flameless combustor 13 is connected with a hydrogen pipeline 21, and a hydrogen bottle 17 is controlled by a hydrogen flowmeter 16 to provide hydrogen; the primary air inlet pipeline 28 is connected with the primary air nozzle 2 and used for providing primary air for the primary air nozzle, and meanwhile, the primary air inlet pipeline 28 is respectively connected with the first oxygen inlet pipeline 22 and the first water vapor inlet pipeline 24, and primary air is obtained after oxygen and water vapor are mixed; the secondary air inlet pipeline 23 is connected with the secondary air nozzle 3 and used for providing secondary air for the secondary air nozzle, and meanwhile, the secondary air inlet pipeline 23 is respectively connected with the second oxygen inlet pipeline 29 and the second steam inlet pipeline 26, and secondary air is obtained by mixing oxygen and steam; the oxygen cylinder 15 provides oxygen to the first oxygen inlet line 22 and the second oxygen inlet line 29 and monitors the flow value thereof through the oxygen flow meter 14; the third steam inlet line 25 is connected to the first steam nozzle 5 for supplying steam as a diluent to the combustion chamber 11; the flue gas generated in the combustion chamber 11 enters the first steam inlet pipeline 24, the second steam inlet pipeline 26 and the third steam inlet pipeline 25 through the flue gas pipeline 30 and the flue gas circulation pipeline 27, and is pressurized by the first booster fan 19, the second booster fan 32 and the third booster fan 18 to provide the water vapor for the combustion chamber 11, and the residual flue gas in the combustion chamber 11 enters the water catching tank 20 through the water catching pipeline 31 to catch water.
The specific operation of the hydrogen-steam oxygen-enriched flameless combustor provided by the present invention is further described below.
In the preheating stage, hydrogen, steam and primary air are respectively introduced into the hydrogen spray pipe 1, the first steam spray pipe 5 and the primary air spray pipe 2, the bluff body 6 is close to the outlet of the hydrogen spray pipe 1, the steam and the primary air enter the combustion chamber 11 in a rotational flow mode, are rapidly combusted with the hydrogen and form stable flame on the bluff body 6, after the temperature of the combustion chamber 11 is higher than the self-ignition point of the hydrogen, the flow in the first steam spray pipe 5 and the primary air spray pipe 2 is gradually reduced until the flow is closed, the flow in the second steam spray pipe 10 and the secondary air spray pipe 3 is gradually increased until the preset target is reached, the bluff body 6 is far away from the outlet of the hydrogen spray pipe 1 to be close to the wall surface of the combustor 11, a secondary air nozzle is sprayed at a high speed and then enters the combustion chamber 11, a large amount of flue gas is sucked and mixed with the hydrogen to realize flameless combustion, and the flue gas generated in the combustion process, therefore, the smoke can be introduced into the first heat-preservation pipeline 4 and the second heat-preservation pipeline 9 to preheat water vapor, primary air and secondary air, and meanwhile, the smoke can be introduced into the first water vapor spray pipe 5 and the second water vapor spray pipe 10 due to the fact that the main component in the smoke is the water vapor, the smoke can be mixed with oxygen to obtain the primary air and the secondary air, so that the enrichment of the water vapor in the smoke is achieved, and finally, the water in the smoke is collected by the water collecting tank 20.
It will be understood by those skilled in the art that the foregoing is merely a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included within the scope of the present invention.