Utilize multistage ammonia gas combustor of MILD burning
Technical Field
The invention belongs to the technical field of combustors, and particularly relates to a multistage ammonia combustor utilizing MILD combustion.
Background
Ammonia does not contain carbon, has the advantages of high hydrogen density, low production cost, perfect infrastructure and the like, and is widely concerned as a renewable fuel. However, the application of ammonia is hindered by the problems of unstable flame of ammonia combustion and high emission of nitrogen oxides.
MILD combustion is a MILD combustion mode under low oxygen dilution conditions characterized by: the reaction rate is low, the local heat release is less, the heat flow distribution is uniform, the combustion peak temperature is low, the noise is extremely low, the generation amount of pollutants such as NOx, CO and the like is extremely low, the overall temperature of a hearth is improved, and the radiation heat exchange is enhanced.
The existing ammonia gas burner technology has low-nitrogen combustion technologies such as staged combustion, multi-stage rotational flow, hydrogen doping, flue gas recirculation and the like, and the existing ammonia gas burner generally has the technical problems in the using process: after the fuel is sprayed out, the fuel is quickly ignited by high-temperature air smoke, so that the temperature close to a combustion chamber is too high, the temperature near a swirl blade and an air inlet pipeline is too high, the strength of a workpiece is seriously reduced under the action of high temperature and air, and the service life is greatly reduced; the fuel and the air are not uniformly mixed, the combustion is insufficient, and the combustion efficiency is low; under different loads, the combustion condition of a hearth is changed, the generation amount of NOx is greatly changed, and the existing burner cannot be adopted for ammonia combustion.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a multistage ammonia gas burner using MILD combustion, so as to improve the combustion efficiency and reduce the discharge amount of nitrogen oxides; moreover, by adopting the burner, the gas ignition speed is high, the flame is stable, and the probability of backfire and misfire is reduced.
In order to achieve the purpose, the invention adopts the technical scheme that:
a multistage ammonia gas burner using MILD combustion is characterized by comprising a first-stage combustion structure, a tangential air inlet structure and a second-stage combustion structure;
the primary combustion structure comprises a primary ammonia gas inlet pipeline, the primary ammonia gas inlet pipeline is communicated with a primary combustion chamber, a flame stabilizing disc is arranged outside the primary ammonia gas inlet pipeline, the front end face of the flame stabilizing disc is connected with a windproof cover, and the primary combustion chamber is positioned inside the windproof cover to realize MILD combustion;
the tangential air inlet structure comprises an air inlet pipeline and a hydrogen inlet pipeline, the air inlet pipeline and the hydrogen inlet pipeline are connected to the side wall of the primary ammonia inlet pipeline, and air and hydrogen are fed into the primary ammonia inlet pipeline to form a rotational flow;
the secondary combustion structure comprises a secondary air blower and a secondary ammonia gas inlet pipeline, the front end of the secondary ammonia gas inlet pipeline extends into the secondary combustion chamber, the secondary combustion chamber is located at the front end of the primary combustion chamber and communicated with the primary combustion chamber, and the secondary air blower generates secondary air and sends the secondary air into the secondary combustion chamber.
In one embodiment, the front end of the primary ammonia gas inlet pipeline is connected with the tail end of a spray pipe, the front end of the spray pipe is provided with a nozzle, the nozzle is positioned in the primary combustion chamber, and the spray pipe is in a tapered shape along the fuel flow direction.
In one embodiment, the nozzle is provided with a plurality of injection holes, the injection holes are arranged in a layered mode along the axial direction of the primary ammonia gas inlet pipeline and form included angles with the axial direction, and the injection hole at the lowest layer is located at the bottom of the nozzle and is located on the axial line.
In one embodiment, the connection points of the air inlet pipeline and the hydrogen inlet pipeline and the primary ammonia inlet pipeline are located in the same circumferential direction, and the air inlet pipeline and the hydrogen inlet pipeline are axially and obliquely arranged.
In one embodiment, a rotational flow impeller is arranged between the outer side wall of the front end of the windshield and the inner wall of the combustor shell, and the secondary air forms rotational flow air through the rotational flow impeller and is sent into the secondary combustion chamber.
In one embodiment, the secondary combustion chamber is tapered forward of the swirl impeller.
In one embodiment, a plurality of blades with inclined angles are uniformly arranged on the swirl impeller, and secondary air is fed into the secondary combustion chamber through the swirl impeller to form a primary swirl zone.
In one embodiment, the secondary ammonia gas inlet pipeline is provided with a plurality of secondary ammonia gas inlet pipelines which are uniformly distributed on the outer side of the primary ammonia gas inlet pipeline, and each secondary ammonia gas inlet pipeline penetrates through the flame stabilizing disc and is symmetrically distributed around the axis.
In one embodiment, the secondary ammonia gas inlet pipeline adopts a straight nozzle, and the nozzle is inwardly folded to form an included angle with the axial direction, so that a secondary cyclone area is formed.
In one embodiment, the secondary ammonia gas inlet pipeline is connected with a groove on an axial fixed pipeline through a baffle plate, and the position and the length of the secondary ammonia gas inlet pipeline in the secondary combustion chamber are adjusted by moving the gear of the baffle plate on the fixed pipeline.
Compared with the prior art, the invention has the beneficial effects that:
1. the combustor is the stage combustor, can promote the mixture of gas and air, promotes the gas combustion for the combustion chamber heat load is more even, thereby reduces nitrogen oxide's emission.
2. The combustion device introduces a flue gas backflow technology, and flue gas flows back to the primary combustion chamber under the action of pressure after being sprayed out through the spray pipe, so that the concentration of fuel gas can be reduced, MILD combustion is realized, and the emission of nitrogen oxides is reduced.
3. The air inlet pipeline is provided with the moving device, so that the position of a combustion area can be adjusted according to the change of flow, and the combustion efficiency is improved.
Drawings
FIG. 1 is a schematic diagram of the present invention.
FIG. 2 is a schematic view of the combination of a primary combustion configuration and a tangential air intake configuration of the present invention.
FIG. 3 is a schematic view of the arrangement structure of the secondary ammonia gas inlet pipeline on the flame stabilizing disc.
Fig. 4 is a schematic structural view of the fixed pipe of the present invention.
Detailed Description
The embodiments of the present invention will be described in detail below with reference to the drawings and examples.
As shown in fig. 1 and 2, the present invention is a multistage ammonia gas burner using mld combustion, which comprises a primary combustion structure, a tangential air intake structure and a secondary combustion structure, or consists of only the primary combustion structure, the tangential air intake structure and the secondary combustion structure. Several of the structures described above may be arranged in the burner housing 6.
In the present invention, the flow direction is defined as "from back to front" with the flow direction of the fuel or air as a reference direction. In the present invention, the axial direction refers to the axial direction of the burner, which is parallel to or coincides with the main flow direction of the fuel.
The front end of the multi-stage cyclone burner is connected with a combustion chamber, and the rear end of the multi-stage cyclone burner is provided with an air inlet device and a gas valve bank.
In the invention, the primary combustion structure mainly comprises a primary ammonia gas inlet pipeline 1, and the primary ammonia gas inlet pipeline 1 is communicated with a primary combustion chamber 7. The outside of one-level ammonia admission line 1 sets up steady flame dish 10, and the wind cap 5 of cylindric is connected to the terminal surface before steady flame dish 10, and one-level combustion chamber 7 is located inside wind cap 5, through wind cap 5 isolation air, forms the negative pressure zone in the combustion process, helps producing the backward flow, inhales back partial combustion flue gas. The sucked flue gas mixed fuel reduces the concentration of oxygen, forms dispersed combustion, realizes MILD combustion, slows down combustion reaction, reduces flame temperature, enables the combustion temperature to be uniformly distributed, and reduces the emission of nitrogen oxides. And provides heat to the secondary combustion chamber 14 to achieve the ignition effect. Obviously, an ignition device for igniting the gas is provided in the primary combustion chamber 7.
The tangential air inlet structure mainly comprises an air inlet pipeline 2 and a hydrogen inlet pipeline 13, wherein the air inlet pipeline 2 and the hydrogen inlet pipeline 13 are connected to the side wall of the primary ammonia gas inlet pipeline 1, and air and hydrogen are fed into the primary ammonia gas inlet pipeline 1 to form a rotational flow. Obviously, the connection is preferably tangential.
The secondary combustion structure mainly comprises a secondary air blower 8 and a secondary ammonia gas inlet pipeline 9, the front end of the secondary ammonia gas inlet pipeline 9 extends into a secondary combustion chamber 14, the secondary combustion chamber 14 is located at the front end of the primary combustion chamber 7 and communicated with the primary combustion chamber 7, and the secondary air blower 8 generates secondary air and sends the secondary air into the secondary combustion chamber 14. It is clear that the primary combustion chamber 7 and the secondary combustion chamber 14 can be two parts of one integral zone.
In a specific structure of the invention, the primary combustion structure further comprises a spray pipe 3, a nozzle 4 and the like, the front end of the primary ammonia gas inlet pipeline 1 is connected with the tail end of the spray pipe 3, the spray pipe 3 is in a tapered shape along the fuel flow direction, and the acceleration of the primary ammonia gas and primary air mixed gas is realized by changing the section and reducing the pressure so as to realize high-speed jet. The nozzle 4 is mounted at the front end of the lance 3 and it is evident that the nozzle 4 is located within the primary combustion chamber 7 for feeding a high velocity gas stream into the primary combustion chamber 7.
Illustratively, the nozzle 4 has a plurality of injection holes, and each injection hole is arranged in layers along the axial direction of the primary ammonia gas inlet pipeline 1 and forms an included angle with the axial direction. The lowermost injection holes are located at the bottom of the nozzle 4, preferably on the axis, and each injection hole is used to inject the ammonia-air mixture into the primary combustion chamber 7. Through the nozzle 4, the spraying amount of fuel gas can be controlled, a certain speed of jet flow is ensured, a plurality of combustion points are formed at the same time, the combustion in the primary combustion chamber 7 is more uniform and stable, and the combustion efficiency is improved; and also can prevent the flame from flowing backwards.
In a specific structure of the invention, the number of the air inlet pipes 2 and the number of the hydrogen inlet pipes 13 are set as required, in the embodiment shown in fig. 2, there are three air inlet pipes 2 and one hydrogen inlet pipe 13, the connection points of the air inlet pipes 2 and the hydrogen inlet pipes 13 and the primary ammonia inlet pipe 1 are in the same circumferential direction, and the air inlet pipes 2 and the hydrogen inlet pipes 13 are axially and obliquely arranged to feed air and hydrogen in a tangential manner as much as possible and to mix with ammonia in the primary ammonia inlet pipe 1 to form a rotational flow.
In a specific structure of the invention, a rotational flow impeller 11 is arranged between the outer side wall close to the front end of the windshield 5 and the inner wall of the combustor shell 6, and secondary air forms rotational flow air through the rotational flow impeller 11 and then is fed into a secondary combustion chamber 14. Illustratively, in the present invention, the secondary combustion chamber 14 has a gradually widening shape, i.e., a diffuser shroud, in front of the swirl vanes 11. The secondary air rapidly diffuses after entering the secondary combustion chamber 14.
Specifically, a plurality of blades with inclination angles are uniformly arranged on the swirl impeller 11, air is absorbed by the secondary air blower 8, the swirl impeller 11 provides a rotary force for the air, the air enters spirally, and a primary swirl area can be formed at a secondary air outlet.
The secondary ammonia gas inlet pipeline 9 adopts a direct injection structure, the injection nozzle is inwardly folded, a certain included angle is formed between the injection nozzle and the axial direction and the radial direction, a radial force is applied to ammonia gas, a secondary cyclone area is formed at the secondary ammonia gas outlet, and secondary air of the cyclone and secondary ammonia gas of the cyclone are mixed and combusted. The secondary cyclone area is approximately positioned at the initial section of the primary MILD combustion area, so that the stable combustion of large flow is realized, the flame backflow is prevented, and the safety is ensured. Illustratively, a plurality of secondary ammonia gas inlet pipelines 9 are uniformly distributed on the outer side of the primary ammonia gas inlet pipeline 1 in a surrounding manner along the circumferential direction, and each secondary ammonia gas inlet pipeline 9 penetrates through the flame stabilizing disc 10 and is symmetrically distributed around the axis, as shown in fig. 3.
In a specific structure of the invention, in order to adjust combustion conveniently, the secondary ammonia gas inlet pipeline 9 is connected with the groove on the axial fixed pipeline 12 through a baffle, the position and the length of the secondary ammonia gas inlet pipeline 9 in the secondary combustion chamber 14 are adjusted by moving the gear of the baffle on the fixed pipeline 12, the fixed pipeline 12 is structured as shown in fig. 4, grooves with different depths are arranged on the fixed pipeline, the outer wall of each secondary ammonia gas inlet pipeline 9 is provided with a convex symmetrical baffle, the position adjustment of the secondary ammonia gas inlet pipeline 9 in the secondary combustion chamber 14 is realized through the matching of the baffle and the grooves with different depths, and further, the combustion area is moved along with the gas flow.
In above-mentioned combustor, the cooperation of one-level combustion area and second grade combustion area realizes MILD stable combustion, has weakened the appearance of local high temperature, avoids producing the flame refluence, has reduced the emission of pollutant, has realized gas efficiency effectively and has improved.
The above examples are provided only for illustrating the present invention and are not intended to limit the present invention. Changes, modifications, etc. to the above-described embodiments are intended to fall within the scope of the claims of the present invention as long as they are in accordance with the technical spirit of the present invention.