Dual premixed ammonia gas burner

Abstract

A dual-premixed ammonia burner relates to the field of ammonia combustion equipment. Addressing the problems of high ignition energy, slow combustion speed, poor flame stability, and difficulty in achieving stable combustion in large proportions with ammonia, this invention employs a dual premixing structure of auxiliary fuel gas premixed with ammonia and air premixed with ammonia, combined with a three-stage coaxial air duct and a regenerative pre-combustion chamber to achieve stable combustion. The burner includes an ignition gun, a primary air regulating damper, a secondary air regulating damper, a volute-shaped air casing, a primary air annular duct, swirl vanes, an annular ammonia multi-nozzle header, a pre-combustion chamber, a tertiary air multi-nozzle annular pipe, a flame monitor, and dual ammonia and auxiliary fuel inlets. This invention allows for wide load adjustment from 30% to 100%, no flameout at low loads, high burnout rate, and low nitrogen oxide emissions. It can operate with a large proportion of ammonia or pure gas, features a reasonable structure, reliable ignition, and stable safety, and is suitable for zero-carbon retrofitting and efficient utilization of green ammonia in industrial boilers, kilns, and other thermal equipment.

Description

Technical Field

[0001] This invention relates to the field of ammonia combustion equipment, and more particularly to a dual premixed ammonia burner. Background Technology

[0002] Under the development trend of green hydrogen and green ammonia energy, green ammonia, as a zero-carbon fuel, has advantages such as zero carbon emissions from combustion, easy liquefaction, and high energy density for transportation and storage. It is a cost-effective solution for the green transformation of high-energy-consuming and heat industries, and it is in line with the national policy on the promotion and application of green ammonia.

[0003] However, ammonia has problems such as high ignition energy, slow combustion speed, narrow combustion limit, and poor flame stability, making it difficult to achieve stable combustion on its own. Existing burners cannot be adapted to the combustion characteristics of ammonia, making it difficult to achieve safe and stable combustion on a large scale.

[0004] Therefore, the present invention provides a dual premixed ammonia burner, which achieves high-proportion ammonia co-combustion and stable combustion over a wide load by premixing auxiliary fuel gas with ammonia and air with ammonia.

[0005] There is currently no corresponding solution to the above problems. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a dual premixed ammonia burner with a reasonable structure, reliable ignition, stable combustion, the ability to incorporate a large proportion of ammonia, and full-load adjustment.

[0007] The equipment includes a natural gas inlet, which has a built-in ignition gun. The natural gas inlet is connected to a natural gas transmission pipe, the tail end of which is connected to the pre-combustion chamber. A primary air regulating damper is installed on the natural gas transmission pipe; this enables the supply of ignition and combustion-supporting air to the ignition area.

[0008] A volute-shaped air casing for a burner is installed outside the natural gas transmission pipeline, and the volute-shaped air casing for the burner is connected to an external fan through an air intake pipe; a two-stage air conditioning damper is installed on the air intake pipe; The combustion engine volute-shaped casing is equipped with a primary air annular duct and swirl blades inside. The swirl blades are equipped with an annular ammonia multi-nozzle manifold, and a pre-combustion chamber is connected to the rear of the multi-nozzle manifold. The pre-combustion chamber is fitted with a three-stage multi-nozzle annular pipe in the middle; that is, the main swirling air volume is adjusted by a two-stage air regulating damper.

[0009] The pre-combustion chamber is also equipped with a flame monitor and a fire observation hole on its outer wall.

[0010] A main ammonia inlet is provided in front of the volute-shaped air casing of the burner, and a stable ammonia inlet is provided below and behind it; an auxiliary fuel inlet is also provided on the side of the stable ammonia inlet.

[0011] Furthermore, the burner's volute-shaped air casing has a three-layer coaxial nested air duct structure inside. The inner layer is a primary air annular air duct, the middle layer is a secondary air duct, and the outer layer is a tertiary air multi-nozzle annular pipe. The tertiary air multi-nozzle annular pipe is fixed to the inner wall of the air casing outside the pre-combustion chamber outlet.

[0012] This ensures that the air supply paths at each level are regular and that the airflow does not interfere with each other, achieving precise air distribution at different levels, improving the swirling mixing effect, reducing flow resistance, and enhancing combustion stability in the outlet area.

[0013] The beneficial effects of this invention are as follows: This invention adopts a dual premixing structure and a staged air supply design, namely, premixing auxiliary fuel with ammonia and staged premixing of air with ammonia, effectively solving the problems of difficult ammonia ignition, slow combustion speed, and poor flame stability. It can achieve high-proportion ammonia-blended combustion and stable operation under wide loads. The three-layer coaxial air duct ensures precise air distribution and thorough mixing, the pre-combustion chamber's heat storage structure ensures no flameout under low loads, and the dual ammonia supply balances ignition stability and main combustion. Combined with independent airflow regulation and monitoring devices, this makes the burner ignition reliable, flexible in adjustment, and has a high burnout rate, while simultaneously reducing nitrogen oxide emissions. The overall structure is reasonable, safe, and efficient, fully adaptable to the zero-carbon combustion application requirements of industrial boilers and kilns. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of an embodiment of the dual premixed ammonia burner described in this invention; Figure 2 This is a schematic diagram of the partial assembly relationship structure of a dual premixed ammonia burner according to the present invention; Figure label: 1-Ignition gun 2-Primary air conditioning damper 3-Burner volute-shaped air casing 4-Primary air annular duct 5-Swirl vane 6-Annular ammonia multi-nozzle header 7-Pre-combustion chamber 8-Tertiary air multi-nozzle annular pipe 9-Secondary air conditioning damper 10-Flame monitor 11-Observation hole 12-Stable combustion ammonia inlet 13-Mainstream ammonia inlet 14-Auxiliary fuel inlet; The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0015] Reference Figure 1 , Figure 2 The present invention provides a dual premixed ammonia burner, which includes a natural gas inlet and an ignition gun 1 built into the natural gas inlet. The natural gas inlet is connected to the natural gas transmission pipe, the tail end of which is connected to the pre-combustion chamber 7. A primary air regulating damper 2 is installed on the natural gas transmission pipe; that is, to supply ignition and combustion-supporting air to the ignition area.

[0016] A volute-shaped air casing 3 for a burner is installed outside the natural gas transmission pipe. The volute-shaped air casing 3 is connected to an external fan through an air intake pipe. A two-stage air conditioning damper 9 is installed on the air intake pipe. The combustion engine volute-shaped air casing 3 is provided with a primary air annular air duct 4 and swirl blades 5 inside; The swirl blade 5 is equipped with an annular ammonia multi-nozzle manifold 6 around its periphery, and a pre-combustion chamber 7 is connected to the rear of the multi-nozzle manifold. The pre-combustion chamber 7 is fitted with a three-stage air multi-nozzle annular pipe 8 in the middle; that is, the main swirling air volume is adjusted by the two-stage air regulating damper 9.

[0017] The outer wall of the pre-combustion chamber 7 is also equipped with a flame monitor 10 and a fire observation hole 11.

[0018] A main ammonia inlet 13 is provided in front of the volute-shaped air casing 3 of the burner, and a stable ammonia inlet 12 is provided below and behind it; an auxiliary fuel inlet 14 is also provided on the side of the stable ammonia inlet 12.

[0019] Example 1: The burner volute-shaped air casing 3 has a three-layer coaxial nested air duct structure inside. The inner layer is a primary air annular air duct 4, the middle layer is a secondary air duct, and the outer layer is a tertiary air multi-nozzle annular pipe 8. The tertiary air multi-nozzle annular pipe 8 is fixed to the inner wall of the air casing outside the outlet of the pre-combustion chamber 7.

[0020] This ensures that the air supply paths at each level are regular and that the airflow does not interfere with each other, achieving precise air distribution at different levels, improving the swirling mixing effect, reducing flow resistance, and enhancing combustion stability in the outlet area.

[0021] In Example 2, the stable combustion ammonia inlet 12 and the auxiliary fuel inlet 14 are connected in parallel to the premixing chamber inside the pre-combustion chamber 7, and the main ammonia inlet 13 is connected to the air inlet side of the primary air ring duct 4. The two ammonia streams are used for ignition and stable combustion and main combustion, respectively.

[0022] The effect achieved is a clear division of labor between ignition and stable combustion and main combustion, which can quickly establish a stable ignition flame, take into account both stable combustion under low load and efficient combustion under high load, and support the co-firing of ammonia in a large proportion.

[0023] In Example 3, the flame monitor 10 and the observation hole 11 are coaxially mounted on the side wall of the outlet end of the pre-combustion chamber 7, and both are fixed to the outer wall of the volute-shaped wind shell and sealed and isolated.

[0024] This is to improve the accuracy and real-time performance of flame monitoring, ensure safe and controllable operation, maintain a stable temperature field in the cavity, and prevent air and heat leakage.

[0025] Example 4: The annular ammonia multi-nozzle manifold 6 is installed on the upper inner wall of the pre-combustion chamber 7, with the nozzle facing the central axis of the pre-combustion chamber 7, and is used to supplement the combustion center with stable ammonia gas.

[0026] This means that precise afterburning enhances the concentration at the combustion center, widens the combustion limits, strengthens flame rigidity, and significantly reduces the risk of flameout under low load.

[0027] Example 5: The primary air conditioning damper 2 and the secondary air conditioning damper 9 independently control the air volume of the corresponding air ducts, and the tertiary air multi-nozzle annular pipe 8 is used to assist in improving the burnout rate and reducing nitrogen oxide emissions.

[0028] This means achieving independent and flexible adjustment of air volume, improving full-load adaptability and fuel burnout rate, and effectively reducing nitrogen oxide emissions.

[0029] Example 6: The inner wall of the pre-combustion chamber 7 is made of heat-storing refractory material, which maintains flame stability through heat storage and continuous heat release, and achieves stable combustion at low load of 30%~40%.

[0030] The effect achieved is to provide a continuous and stable heat source for combustion, ensure stable combustion without flameout under low load, and significantly expand the burner load adjustment range.

[0031] The working principle of this invention is as follows: The equipment uses the volute-shaped air casing 3 of the burner as the overall assembly base, with three layers of air ducts coaxially nested inside: a primary air annular duct 4, a secondary air duct, and a tertiary air multi-nozzle annular pipe 8. The pre-combustion chamber 7 is located at the central axis, serving as the core stable combustion chamber. The fuel system is supplied in three ways: stable combustion ammonia gas enters the pre-combustion chamber 7 through the stable combustion ammonia gas inlet 12, auxiliary fuel enters through the auxiliary fuel inlet 14, and mainstream ammonia gas enters the primary air annular duct 4 through the mainstream ammonia gas inlet 13. The annular ammonia multi-nozzle header 6 is installed on the inner wall of the pre-combustion chamber 7 for directional ammonia supplementation and stable combustion. Airflow control is independently executed by the primary air regulating damper 2 and the secondary air regulating damper 9. The ignition gun 1 extends into the ignition area inside the pre-combustion chamber 7, and the flame monitor 10 and the observation hole 11 are aligned with the flame area at the outlet of the pre-combustion chamber 7. The whole system forms a complete operating structure of graded feeding, layered air supply, and progressive combustion.

[0032] The equipment operation is divided into three stages: ignition and stable combustion, load increase, and full-load operation. In the ignition and stable combustion stage, the blower starts and completes furnace purging. After the safety conditions are met, the ignition gun 1 ignites, and at the same time, the stable combustion ammonia inlet 12 and the auxiliary fuel inlet 14 are opened. The mixed gas forms an easily ignitable gas in the pre-combustion chamber 7 and is ignited. The heat storage material on the inner wall of the pre-combustion chamber 7 continuously releases heat. With the ammonia replenishment from the annular ammonia multi-nozzle header 6, the combustion is stabilized in the low load range of 30%~40%. The primary air regulating damper 2 delivers a small air volume, and the secondary air regulating damper 9 and the tertiary air multi-nozzle annular pipe 8 maintain a slight airflow assistance. During the load increase phase, once the temperature of the pre-combustion chamber 7 reaches the standard, the main ammonia inlet 13 is opened. The main ammonia and primary air are premixed in the primary air annular duct 4, and after being further mixed by the swirl vanes 5, it is injected into the pre-combustion chamber 7. The air volume of the primary and secondary air is gradually increased, and the tertiary air multi-nozzle annular pipe 8 is opened as needed to achieve a smooth load increase. During the full-load operation phase, the main ammonia-air premixed gas is used as the main fuel for complete combustion. The primary air provides swirl-assisted combustion, the secondary air improves the burnout effect, and the tertiary air multi-nozzle annular pipe 8 regulates the temperature and nitrogen oxide emissions. The pre-combustion chamber 7 maintains stable combustion, and the flame monitor 10 monitors the entire process. The equipment can switch between a large proportion of ammonia blending and pure gas modes to achieve stable, efficient, and low-emission operation.

[0033] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of the invention is defined by the appended claims rather than the foregoing description, and all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0034] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A dual premixed ammonia burner comprising a natural gas inlet, characterized in that: The natural gas inlet has a built-in ignition gun and is connected to a natural gas transmission pipe, the tail end of which is connected to the pre-combustion chamber. A primary air conditioning damper is installed on the natural gas transmission pipe. A volute-shaped air casing for a burner is installed outside the natural gas transmission pipeline, and the volute-shaped air casing for the burner is connected to an external fan through an air intake pipe; a two-stage air conditioning damper is installed on the air intake pipe; The combustion engine volute-shaped casing is equipped with a primary air annular duct and swirl blades inside. The swirl blades are equipped with an annular ammonia multi-nozzle manifold, and a pre-combustion chamber is connected to the rear of the multi-nozzle manifold. The pre-combustion chamber is fitted with a three-stage multi-nozzle annular pipe; that is, the main swirling air volume is adjusted by a two-stage air regulating damper. The pre-combustion chamber exterior wall is also equipped with a flame monitor and observation hole; A main ammonia inlet is provided in front of the volute-shaped air casing of the burner, and a stable ammonia inlet is provided below and behind it; an auxiliary fuel inlet is also provided on the side of the stable ammonia inlet.

2. A dual premixed ammonia burner according to claim 1, characterized in that, The burner's volute-shaped air casing has a three-layer coaxial nested air duct structure. The inner layer is a primary air annular air duct, the middle layer is a secondary air duct, and the outer layer is a tertiary air multi-nozzle annular pipe. The tertiary air multi-nozzle annular pipe is fixed to the inner wall of the air casing outside the pre-combustion chamber outlet.

3. The dual premixed ammonia burner according to claim 1, characterized in that, The ammonia gas inlet for stable combustion and the auxiliary fuel inlet are connected in parallel to the premixing chamber inside the precombustion chamber. The main ammonia gas inlet is connected to the air inlet side of the primary air ring duct. The two ammonia gas inlets are used for ignition and stable combustion and main combustion, respectively.

4. The dual premixed ammonia burner according to claim 1, characterized in that, The flame monitor and the observation hole are coaxially installed on the side wall of the pre-combustion chamber outlet, and both are fixed to the outer wall of the volute-shaped wind casing and sealed and isolated.

5. A dual premixed ammonia burner according to claim 1, characterized in that, The annular ammonia multi-nozzle header is installed on the upper inner wall of the pre-combustion chamber, with the nozzles facing the central axis of the pre-combustion chamber, and is used to supplement the combustion center with stable ammonia gas.

6. A dual premixed ammonia burner according to claim 1, characterized in that, The primary and secondary air conditioning dampers independently control the air volume of their respective ducts, while the tertiary multi-nozzle annular pipe is used to assist in improving the burnout rate and reducing nitrogen oxide emissions.

7. A dual premixed ammonia burner according to claim 1, characterized in that, The inner wall of the pre-combustion chamber is made of heat-storing refractory material, which maintains flame stability through heat storage and continuous heat release, achieving stable combustion at a low load of 30%~40%.

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