An ammonia low-nitrogen submerged combustion device and method

Abstract

This invention discloses a low-NOx submerged combustion device and method for ammonia. The submerged combustion device includes a heating pool, an ammonia burner, a flue, and a heat exchange tube bundle; the heating pool is filled with liquid, and the flue and heat exchange tube bundle are submerged below the liquid surface; the combustion device also includes an ammonia regeneration tank, the lower part of which is located below the liquid surface in the heating pool, and the upper end extending beyond the top of the heating pool; the ammonia regeneration tank has two spray facilities on its side wall, the upper spray facility I is used to introduce and spray liquid above the liquid inlet into the ammonia regeneration tank, and the lower spray facility II is connected to the outlet of the aeration mixture pump; the ammonia burner is used for combustion under oxygen-deficient conditions. The low-NOx submerged combustion device of this invention can achieve efficient low-NOx combustion and simplifies the denitrification equipment required in traditional combustion systems.

Description

Technical Field

[0001] This invention belongs to the field of thermal energy engineering technology, specifically relating to an ammonia low-nitrogen immersion combustion device and method. Background Technology

[0002] The demand for energy-saving, emission-reduction, and carbon-reducing technologies in industrial production is becoming increasingly urgent, and replacing traditional fossil fuels with new environmentally friendly fuels is an important measure. Ammonia is widely recognized as the 2.0 version of hydrogen energy, inheriting the excellent characteristics of hydrogen in terms of environmental protection and high calorific value. In terms of energy storage and transportation, ammonia can be liquefied at -33℃ or 7-8 atmospheres at room temperature, overcoming the difficulty of storing and transporting hydrogen energy. Therefore, ammonia is considered to be the most promising new energy source at present.

[0003] In terms of combustion technology, submerged combustion technology has attracted widespread attention due to its extremely high combustion efficiency, and has already seen some typical applications in LNG gasification and waste treatment. For example, patent CN 108178214 A discloses a two-stage submerged combustion evaporation integrated treatment method for organic waste liquid. This patent divides the evaporator into two evaporation chambers, thereby achieving two-stage staged submerged combustion evaporation. Using this method can improve evaporation concentration efficiency, save energy, and simplify equipment and processing procedures.

[0004] However, while submerged combustion technology offers high combustion efficiency and produces lower flue gas temperatures, it also presents significant challenges in removing nitrogen oxides (NOx) from the low-temperature flue gas. Even with the aid of denitrification catalysts, the required temperature cannot be met. For example, patent CN112963857A discloses an ultra-low NOx emission submerged combustion gasification system and a waste heat recovery process for flue gas denitrification. This patent includes a hot air furnace, where a burner generates the heat required for flue gas denitrification. After denitrification, the flue gas exchanges heat with liquid in a water tank before being discharged. While this equipment can achieve flue gas denitrification, it is relatively complex and difficult to maintain. Furthermore, when the submerged burner uses nitrogen as fuel, the high NOx concentration in the flue gas necessitates additional energy consumption for denitrification. Summary of the Invention

[0005] In view of the problems existing in the prior art, the purpose of this invention is to provide an ammonia low-nitrogen immersion combustion device and combustion method.

[0006] According to a first aspect of the present invention, the present invention provides an ammonia low-NOx immersion combustion device.

[0007] The ammonia low-NOx immersion combustion device of the present invention includes a heating pool, an ammonia burner, a flue, and a heat exchange tube bundle; the heating pool is filled with liquid, and the flue and heat exchange tube bundle are immersed below the liquid surface;

[0008] The combustion equipment is characterized in that it further includes an ammonia regeneration tank, the lower part of which is located below the liquid level in the heating pool, and the upper end extends out of the top of the heating pool; the ammonia regeneration tank is provided with two spraying facilities, the upper spraying facility I is used to introduce liquid and spray it into the ammonia regeneration tank when the liquid level in the heating pool is higher than the liquid inlet of spraying facility I, and the lower spraying facility II is connected to the liquid outlet of the aeration mixture pump;

[0009] The bottom of the ammonia regeneration tank is located at the end of the flue, and the waste heat of the flue gas is used to heat the liquid at the bottom of the ammonia regeneration tank to achieve gas-liquid separation.

[0010] Furthermore, the ammonia regeneration tank is equipped with a gas ejector device at its upper end, used to eject and carry out the regeneration gas from the top of the ammonia regeneration tank. The gas ejector device can adopt a conventional structure in the art. A typical ejector device includes a nozzle and an ejector throat, with the nozzle outlet extending into the ejector throat. The nozzle inlet is connected to the combustion air inlet, and the ejector throat outlet leads to a booster fan, where the gas is pressurized and then introduced into the combustion air inlet of the ammonia burner.

[0011] Furthermore, the ammonia regeneration tank is provided with a drain outlet at the bottom and connected to a liquid pump, which is used to discharge the liquid at the bottom of the ammonia regeneration tank and lead it back to the heating pool or discharge it.

[0012] The ammonia burner uses ammonia as fuel and burns under oxygen-deficient conditions. The downstream outlet of the ammonia burner is connected to a flue, and a flue gas distributor is installed on the flue wall to discharge the combustion gases into the heating pool liquid.

[0013] Furthermore, the ammonia burner can be a conventional top-fired burner in the art. This invention recommends a top-fired ejector-diffusion combustion method. The ammonia burner body consists of two layers: an outer burner shell and an inner burner nozzle. The top of the burner shell is connected to the fuel ammonia pipeline. The burner nozzle has a two-layer structure. The inner layer has a regenerative catalytic cracking body around a vertical axis. The regenerative catalytic body is a gradually contracting inverted frustum structure from the top inlet to the middle section, and a cylindrical structure from the middle section to the bottom outlet. The regenerative catalytic cracking body is filled with a uniform mixture of ceramic regenerative balls and ammonia cracking catalyst, and is surrounded by a highly permeable metal fiber mesh. An outer layer structure surrounds the inner regenerative catalytic cracking body inside the burner nozzle. A combustion air inlet is located on the side of the outer layer of the nozzle and is connected to the combustion air pipeline. The upper half of the outer layer of the nozzle is a cylindrical structure with a diameter that gradually narrows from the middle to the bottom outlet. This design can accelerate the injection speed of the combustion air and enhance the injection intensity of the internal gas.

[0014] Furthermore, a flue gas return channel is provided between the inner side of the burner housing and the outer side of the burner nozzle, which is used to allow high-temperature flue gas to return to the burner nozzle to heat the regenerable catalytic cracking body, thereby keeping the ammonia cracking catalyst active.

[0015] Furthermore, the combustion equipment is also equipped with an aeration mixture pump for fully mixing and absorbing ammonia in the gas phase. The gas phase inlet of the aeration mixture pump is located at the outer end of the hollow drive shaft of the aeration mixture pump and is connected to the flue pipe at the top of the heating tank; the liquid inlet of the mixture pump is located on the side wall of the mixing chamber of the aeration mixture pump and is connected to the liquid outlet pipe on the side wall of the heating tank; the mixture outlet of the mixture pump is connected to the liquid inlet at the bottom of the ammonia regeneration tank.

[0016] Furthermore, the aeration mixture pump can be a conventional two-phase flow pump in the art, or it can be the pump recommended in this invention. The aeration mixture pump recommended in this invention includes: a housing, a motor, a drive shaft, a cam disc, a telescopic rod, and a spring-loaded one-way valve. The motor is located outside the aeration mixture pump housing and is used to provide power to the aeration mixture pump. The motor is fixedly connected to the cam disc located inside the aeration mixture pump housing via the drive shaft. The cam disc is not in fixed contact with the telescopic rod, and the side of the cam disc that contacts the telescopic rod is convex. As the cam disc rotates, the concave and convex surfaces push or pull the telescopic rod to perform a reciprocating piston movement.

[0017] Furthermore, a partitioned baffle is provided downstream of the aeration mixture pump housing. The upstream (left) section of the partitioned baffle is the aeration mixing zone, and the downstream (right) section is the liquid outlet zone. A cylindrical groove is formed in the center of the partitioned baffle to fix the drive shaft. Several channels are provided in the partitioned baffle corresponding to the position of the telescopic rod to fix the telescopic rod, forming a sealed cavity with the hollow structure inside the telescopic rod to discharge the solution. One end of the telescopic rod is not in fixed contact with the cam disc, and the other end is connected to a spring check valve. Each outlet of the spring check valve is equipped with a reverse-flowing spring check valve for liquid backflow prevention.

[0018] Furthermore, the telescopic rod has a liquid inlet in the middle section and a hollow structure on the right side that is narrow in the middle and wide at both ends. When the motor drives the cam disc to rotate, the telescopic rod will be pushed by the cam disc to perform reciprocating telescopic motion. When the telescopic rod extends, the spring one-way valve inside the telescopic rod seals the liquid inlet, while the spring one-way valve at the liquid outlet opens, allowing the solution contained in the cavity inside the telescopic rod to be discharged from the liquid outlet. When the telescopic rod retracts, the spring one-way valve outside the liquid outlet closes to prevent the solution in the liquid outlet area from flowing back, while the spring one-way valve inside the telescopic rod opens, allowing the cavity of the telescopic rod to begin replenishing the solution drawn into the aeration mixing zone. There are two or more telescopic rods, evenly distributed around the circumference of the cam disc.

[0019] Furthermore, the drive shaft is a hollow structure, and a through hole is opened in the inner half of the drive shaft inside the aeration mixing pump to aerate gas into the inner cavity of the aeration mixing pump to achieve gas-liquid mixing.

[0020] Furthermore, the lower end of the liquid outlet area on the right side of the aeration mixture pump is provided with a liquid output port, which is connected to the ammonia regeneration tank through a mixed liquid output pipeline. Furthermore, the upper end of the aeration mixture pump is equipped with a pressure relief port for discharging insoluble gases.

[0021] Furthermore, the heating pool has a closed structure, that is, the upper end of the heating pool is provided with a cover, and the flue gas is discharged only through the flue gas outlet on the side wall of the heating pool, with no flue gas escaping from the top.

[0022] Furthermore, the inlet and outlet of the heat exchange tube bundle are LNG (liquefied natural gas) inlet and NG (natural gas) outlet, respectively.

[0023] Furthermore, the LNG cold flow inlet is located close to the right outlet of the heating pool to reduce the temperature of the liquid output from the heating pool outlet, thereby improving the absorption capacity of the liquid in the aeration mixing pump for ammonia.

[0024] According to a second aspect of the present invention, the present invention provides a method for low-NOx immersion combustion of ammonia gas, wherein the above-described ammonia low-NOx immersion combustion equipment is used.

[0025] Specifically, the ammonia low-NOx immersion combustion method includes the following:

[0026] (1) The ammonia burner continues to burn under oxygen-deficient conditions. The high-temperature flue gas generated by the combustion forms a reflux zone in the flared section. Some of the high-temperature flue gas flows into the heat storage catalytic cracking body through the flue gas reflux channel, heating the heat storage body filled inside and keeping the ammonia cracking catalyst active. The ammonia cracking catalyst cracks part of the passing ammonia into nitrogen and hydrogen, so that the combustion can proceed stably.

[0027] (2) The high-temperature flue gas generated by the combustion in step (1) is discharged into the heating pool by the flue gas distributor after passing through the flue. Most of the heat of the flue gas is conducted to the heat exchange tube bundle through the liquid in the heating pool and heats the material in the heat exchange tube bundle; a small part of the heat is conducted to the end of the flue and heats the liquid at the bottom of the ammonia regeneration tank.

[0028] (3) Excess unburned ammonia gas reduces NOx produced by combustion to N2 during the flow of high-temperature flue gas. In addition, some of the unreacted ammonia dissolves in the water in the heating pool, and the other part exists in the upper part of the heating pool in gaseous form. The water produced by combustion is completely converted into liquid and mixed into the water in the heating pool, while nitrogen gas exists in the gaseous zone at the upper part of the heating pool with ammonia gas.

[0029] (4) The liquid and gas in the heating tank are fed into the aeration mixing liquid pump through the liquid outlet pipe and the flue pipe, respectively, and are fully mixed inside. The nitrogen gas that is insoluble in water is discharged through the pressure relief port at the top. The fully mixed ammonia solution is fed into the ammonia regeneration tank through the mixed liquid output pipeline.

[0030] (5) The ammonia solution from the heating tank and the aeration mixing liquid pump respectively is injected into the ammonia regeneration tank through the side inlet of the ammonia regeneration tank. The ammonia solution is heated at the bottom of the ammonia regeneration tank, which reduces the solubility of ammonia and causes the ammonia to be separated and regenerated. The regenerated ammonia is drawn into the combustion air flow by the ejector at the top of the ammonia regeneration tank and returns to the burner for repeated combustion with the combustion air flow.

[0031] Furthermore, the equivalence ratio of the ammonia burner is 1.05 to 1.2.

[0032] Furthermore, the temperature at the surface of the heat transfer liquid in the water tank is preferably 25~35℃.

[0033] Furthermore, the liquid temperature inside the ammonia regeneration tank is 75~95℃, preferably 80~85℃.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. In the ammonia low-NOx immersion combustion device and method of the present invention, the NOx generated by the combustion of ammonia under oxygen-deficient conditions can be reduced by excess fuel ammonia during the process of flue gas flowing from the flue to the flue gas distributor, thereby achieving efficient low-NOx combustion and simplifying the denitrification equipment required by traditional combustion systems.

[0036] 2. The ammonia low-NOx submerged combustion device of the present invention achieves efficient flue gas internal recirculation by setting a flue gas recirculation structure in the burner and utilizing the high back pressure of the submerged burner; and by setting a regenerative catalytic cracking body in the fuel channel, a portion of the fuel ammonia is cracked into hydrogen, which can improve the combustion effect of the fuel gas, increase the combustion speed of the fuel and broaden the combustible limit, thus solving the problem of insufficient combustion stability of ammonia.

[0037] 3. The ammonia low-NOx submerged combustion device of the present invention uses ammonia as fuel, makes full use of the special form of submerged combustion and is supplemented by an aeration mixer, which realizes the recycling of excess ammonia, minimizes the occurrence of ammonia escape, and features safe and reliable overall combustion heat extraction process, simple equipment and operation, high energy utilization rate and obvious energy saving effect.

[0038] 4. The ammonia low-NOx immersion combustion device of the present invention makes full use of the cold energy of LNG and the heat energy of flue gas waste heat, and, together with the aeration mixing liquid pump and the ammonia regeneration tank, realizes the recycling of excess ammonia and suppresses the occurrence of ammonia escape.

[0039] 5. This invention preferably employs an aeration mixing pump with a special structure. The mixing chamber is divided into an aeration mixing zone and a liquid outlet zone by a partitioned barrier, and periodically connected by a cavity inside a telescopic rod. The solution in the aeration mixing zone has a lower ammonia concentration, while the solution discharged from the liquid outlet zone has a higher ammonia concentration. Increasing the ammonia concentration in the discharged liquid helps reduce the pump's discharge volume and lowers the power consumption of the drive motor; furthermore, a higher ammonia concentration also improves the ammonia separation efficiency in the ammonia regeneration tank. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the structure of the ammonia low-nitrogen immersion combustion device of the present invention.

[0041] Figure 2 This is a schematic diagram of the ammonia burner in the ammonia low-nitrogen immersion combustion device of the present invention.

[0042] Figure 3 This is a schematic diagram of the top structure of the ammonia regeneration tank in the ammonia low-nitrogen immersion combustion device of the present invention.

[0043] Figure 4 This is a schematic diagram of the aeration mixing liquid pump in the ammonia low-nitrogen immersion combustion equipment of the present invention.

[0044] In the diagram, the labels correspond to the following component names: 1-Ammonia burner, 101-Regenerative catalytic cracking unit, 102-Burner nozzle, 103-Shell, 2-Flue, 3-Flue gas distributor, 4-Heat exchange tube bundle, 5-Ammonia regeneration tank, 501-Spraying facility I, 502-Drain outlet, 503-Ejector nozzle, 504-Ejector, 505-Ejector throat, 506-Spraying facility II, 6-Combustion air pipeline, 7-Booster fan, 8-Combustion air inlet, 9-Liquid pump, 10-Drain outlet, 11-L 12-NG Inlet, 13-Fuel Ammonia Pipeline, 14-Exhaust Pipe, 15-Liquid Outlet Pipe, 16-Aeration Mixed Liquid Pump, 16-A-Aeration Mixing Zone, 16-B-Liquid Outlet Zone, 1601-Cam Disc, 1602-Drive Shaft, 1603-Telescopic Rod, 1604-Pressure Relief Valve, 1605Ⅰ-Spring Check Valve, 1605Ⅱ-Spring Check Valve, 1606-Motor, 1607-Blocking Body, 1608-Shell, 17-Mixed Liquid Output Pipeline, 18-Heating Pool. Detailed Implementation

[0045] The ammonia low-NOx immersion combustion apparatus and method of the present invention will be described in more detail below with reference to embodiments and accompanying drawings.

[0046] Example 1

[0047] The ammonia low-NOx immersion combustion device of the present invention includes a heating pool 18, an ammonia burner 1, a flue 2, and a heat exchange tube bundle 4; the heating pool 18 is filled with liquid, and the flue 2 and the heat exchange tube bundle 4 are submerged below the liquid surface. The combustion device also includes an ammonia regeneration tank 5, the lower part of which is located below the liquid surface in the heating pool 18, and the upper end extends beyond the top of the heating pool. The side wall of the ammonia regeneration tank 5 is provided with two liquid inlets and spray facilities 501 and 506. The upper liquid inlet I and the spray facilities are used to introduce liquid into and spray it into the ammonia regeneration tank 5 when the liquid level in the heating pool 18 is higher than the liquid inlet I 501. The lower liquid inlet II 506 and the spray facilities are connected to the liquid output pipeline 17 of the aeration mixture pump.

[0048] The bottom of the ammonia regeneration tank 5 is located at the end of the flue 2, and the waste heat of the flue gas can be used to heat the liquid at the bottom of the ammonia regeneration tank 5 to achieve gas-liquid separation.

[0049] The ammonia regeneration tank is equipped with a gas ejector 504 at its upper end, used to eject and carry out the regeneration gas from the top of the ammonia regeneration tank 5. The ejector 504 can adopt a conventional structure in the art. A typical ejection device includes an ejector nozzle 503 and an ejector throat 505, with the outlet of the ejector nozzle 503 extending into the interior of the ejector throat 505. The inlet of the ejector nozzle 503 is connected to the combustion air pipeline 6, and the outlet of the ejector throat 505 leads to the booster fan 7, and after being pressurized by the booster fan 7, it is introduced into the combustion air inlet 8 of the ammonia burner.

[0050] The bottom of the ammonia regeneration tank 5 is provided with a drain port 502 and connected to a liquid pump 9, which is used to discharge the liquid at the bottom of the ammonia regeneration tank 5 and circulate it back to the heating pool 18 or discharge it through the drain port 10.

[0051] The ammonia burner 1 uses ammonia as fuel and burns under oxygen-deficient conditions. The downstream outlet of the ammonia burner 5 is connected to the flue 2, and a flue gas distributor 3 is installed at the tail end of the flue 2 to discharge the flue gas after combustion into the liquid in the heating pool 18.

[0052] The ammonia burner 1 adopts a top-fired ejector diffusion combustion method. The main body of the burner 1 is divided into inner and outer layers. The outer layer is the burner shell 103, and the inner layer is fitted with the burner nozzle 102. The top of the burner shell 103 is connected to the fuel ammonia pipeline 13. The burner nozzle 102 has an inner and outer layer structure. The inner layer is provided with a regenerative catalytic cracking body 101 around the vertical axis. The regenerative catalytic body 101 is a gradually narrowing inverted frustum structure from the top inlet to the middle section, and a cylindrical structure from the middle section to the bottom outlet. The regenerative catalytic cracking body 101 is filled with a uniform mixture of ceramic regenerative balls and ammonia cracking catalyst, and is wrapped with a metal fiber mesh with good air permeability. The burner nozzle 102 is provided with an outer layer structure around the inner regenerative catalytic cracking body 101. The outer side of the burner nozzle 102 is provided with a combustion air inlet 8 and is connected to the combustion air pipeline. The upper part of the outer layer of the burner nozzle 102 is a cylindrical structure with a diameter that gradually narrows from the middle to the bottom outlet, which accelerates the injection speed of the combustion air and enhances the injection intensity of the internal gas.

[0053] A flue gas return channel is provided between the inner side of the burner housing 103 and the outer side of the burner nozzle 102, which is used to allow high-temperature flue gas to return to the burner nozzle 102 to heat the heat storage catalytic cracking body 101, so as to keep the ammonia cracking catalyst active.

[0054] The combustion equipment is also equipped with an aeration mixing pump 16 for fully mixing and absorbing ammonia in the gas phase. The gas phase inlet of the aeration mixing pump 16 is located at the outer end of the hollow drive shaft 1602 of the aeration mixing pump and is connected to the flue pipe 14 on the side wall of the heating tank 18; the liquid inlet of the aeration mixing pump 16 is located on the side wall of the mixing chamber of the aeration mixing pump 16 and is connected to the liquid outlet pipe 15 on the side wall of the heating tank 18. The liquid output pipeline 17 of the aeration mixing pump 16 is connected to the liquid inlet II 506 at the bottom of the ammonia regeneration tank 5.

[0055] The aeration mixture pump 16 can be a conventional two-phase flow pump in the art, or it can be the pump recommended in this invention. The aeration mixture pump recommended in this invention includes: a housing 1608, a motor 1606, a drive shaft 1602, a cam disc 1601, a telescopic rod 1603, and a spring-loaded one-way valve 1605. The motor 1606 is located outside the aeration mixture pump housing 1608 and is used to provide power to the aeration mixture pump 16. The motor 1606 is fixedly connected to the cam disc 1601 located inside the housing 1608 via the drive shaft 1602. The cam disc 1601 is not in fixed contact with the telescopic rod 1603, and the side of the cam disc 1601 that contacts the telescopic rod 1603 is convex. As the cam disc 1601 rotates, the concave and convex surfaces push or pull the telescopic rod 1603 to perform a reciprocating piston motion.

[0056] A partition barrier 1607 is provided downstream of the housing 1608. Upstream (left side) of the partition barrier 1607 is the aeration mixing zone 16-A, and downstream (right side) is the liquid outlet zone 16-B. The partition barrier 1607 has a cylindrical groove in its center for fixing the drive shaft 1602. The partition barrier 1607 has several channels corresponding to the position of the telescopic rod 1603 for fixing the telescopic rod 1603. Together with the hollow structure inside the telescopic rod 1603, they form a sealed cavity for discharging the solution.

[0057] One end of the telescopic rod 1603 is not in fixed contact with the cam disc 1601, and the other end is connected to the spring check valve 1605Ⅰ; a reverse spring check valve 1605Ⅱ is provided on each side of the liquid outlet of the partition barrier 1607 for liquid check.

[0058] The telescopic rod 1603 has a liquid inlet in the middle section and a hollow structure that is narrow in the middle and wide at both ends on the right side. When the motor 1606 drives the cam disk 1601 to rotate, the telescopic rod 1603 will be pushed by the cam disk 1601 to perform reciprocating telescopic motion. When the telescopic rod 1603 extends in, the spring one-way valve 1605Ⅰ inside the telescopic rod 1603 seals the liquid inlet, and the spring one-way valve 1605Ⅱ at the liquid outlet opens. The solution contained in the cavity inside the telescopic rod 1603 is discharged into the liquid outlet zone 16-B through the liquid outlet downstream of the partition barrier 1607. When the telescopic rod 1603 retracts, the spring one-way valve 1605Ⅱ set outside the liquid outlet downstream of the partition barrier 1607 closes to prevent the solution in the liquid outlet zone 16-B from flowing back, and the spring one-way valve 1605Ⅰ inside the telescopic rod 1603 opens. The cavity of the telescopic rod 1603 begins to replenish the solution in the aeration mixing zone 16-A. There are two or more telescopic rods 1603, which are evenly distributed around the circumference of the cam disk 1601.

[0059] The drive shaft 1602 is a hollow structure, and the drive shaft 1602 has a through hole in the inner half of the aeration mixing pump 16, which is used to aerate gas into the inner cavity of the aeration mixing pump 16 to achieve gas-liquid mixing.

[0060] The aeration mixing pump 16 has a liquid output port on its lower right side, which is connected to the ammonia regeneration tank 5 via a mixed liquid output pipeline 17. Furthermore, the aeration mixing pump 16 is equipped with a pressure relief valve 1604 at its upper end for discharging insoluble gases.

[0061] The heating pool 18 is a closed structure, that is, the upper end of the heating pool 18 is provided with a cover, and the flue gas is discharged into the aeration mixing liquid pump 16 only through the flue pipe 14 on the side wall of the heating pool 18, and there is no flue gas escaping from the top.

[0062] Preferably, the inlet and outlet of the heat exchange tube bundle 4 are an LNG (liquefied natural gas) inlet 11 and an NG (natural gas) outlet 12, respectively. The LNG inlet 11 is close to the liquid outlet pipe 15 on the right side of the heating pool 18, which is used to reduce the temperature of the liquid output from the heating pool 18, thereby improving the absorption capacity of the liquid in the aeration mixing pump 16 for ammonia.

[0063] Example 2

[0064] The present invention provides a method for low-NOx immersion combustion of ammonia, wherein the low-NOx immersion combustion equipment of ammonia described in Example 1 is used.

[0065] Specifically, the ammonia low-NOx immersion combustion method includes the following:

[0066] (1) The ammonia burner 1 continues to burn under oxygen-deficient conditions. The high-temperature flue gas generated by the combustion forms a reflux zone in the flared section. Some of the high-temperature flue gas flows into the heat storage catalytic cracking body 101 through the flue gas reflux channel, heating the heat storage body filled inside and keeping the ammonia cracking catalyst active. The ammonia cracking catalyst cracks part of the passing ammonia into nitrogen and hydrogen, so that the combustion can proceed stably.

[0067] (2) The high-temperature flue gas generated by the combustion in step (1) is discharged into the heating pool 18 by the flue gas distributor 3 after passing through the flue 2. Most of the heat of the flue gas is conducted to the heat exchange tube bundle 4 through the liquid in the heating pool 18 and heats the material in the heat exchange tube bundle 4; a small part of the heat is conducted to the end of the flue 2 and heats the liquid at the bottom of the ammonia regeneration tank 5.

[0068] (3) During the flow of the excess unburned ammonia in the flue 2, part of the NOx produced by combustion is reduced to N2. In addition, part of the unreacted ammonia dissolves in the water in the heating pool 18, and the other part exists in the upper part of the heating pool 18 in gaseous form. The water produced by combustion is completely converted into liquid and mixed into the water in the heating pool 18, while nitrogen and ammonia exist in the gaseous domain at the upper part of the heating pool 18.

[0069] (4) The liquid and gas in the heating tank 18 are fed into the aeration mixing liquid pump 16 through the liquid outlet pipe 15 and the flue pipe 14, respectively, and are fully mixed inside. The nitrogen gas, which is insoluble in water, is discharged through the pressure relief valve 1604 at the top. The fully mixed ammonia solution is fed into the ammonia regeneration tank 5 through the mixed liquid output pipeline 17.

[0070] (5) Ammonia solutions from heating tank 18 and aeration mixing pump 16 are injected into ammonia regeneration tank 5 through the side inlet of ammonia regeneration tank 5. The ammonia solution is heated at the bottom of ammonia regeneration tank 5 to reduce the solubility of ammonia and separate and regenerate ammonia. The regenerated ammonia is drawn into the combustion air flow by ejector 504 at the top of ammonia regeneration tank and returns to ammonia burner 1 for repeated combustion with the combustion air flow.

[0071] Furthermore, the equivalence ratio of the ammonia burner is 1.05 to 1.2.

[0072] Furthermore, the temperature at the surface of the heat transfer liquid in the water tank is preferably 25~35℃.

[0073] Furthermore, the liquid temperature inside the ammonia regeneration tank is 75~95℃, preferably 80~85℃.

[0074] Furthermore, the energy efficiency of the ammonia low-NOx immersion combustion equipment is not less than 97%.

Claims

1. A low-NOx ammonia immersion combustion device, comprising a heating tank, an ammonia burner, a flue, and a heat exchange tube bundle; wherein the heating tank is filled with liquid, and the flue and heat exchange tube bundle are submerged below the liquid surface; characterized in that, The combustion equipment also includes an ammonia regeneration tank and an aeration mixture pump. The lower part of the ammonia regeneration tank is located below the liquid surface in the heating pool, and the upper end extends out of the top of the heating pool; the upper end of the ammonia regeneration tank is equipped with a gas ejector device, which is used to eject and carry out the regeneration gas from the top of the ammonia regeneration tank. The ammonia regeneration tank is equipped with two spray facilities on its side wall. The upper spray facility I is used to introduce and spray liquid above the liquid inlet into the ammonia regeneration tank, and the lower spray facility II is connected to the outlet of the aeration mixture pump. The bottom of the ammonia regeneration tank is placed at the end of the flue, and the waste heat of the flue gas is used to heat the liquid at the bottom of the ammonia regeneration tank to achieve gas-liquid separation. The ammonia burner is used for combustion under oxygen-deficient conditions; the downstream outlet of the ammonia burner is connected to a flue, and a flue gas distributor is installed on the flue wall to discharge the combustion gas into the heating pool liquid. The gas phase inlet of the aeration mixed liquid pump is located at the outer end of the hollow drive shaft of the mixed liquid pump and is connected to the exhaust pipe at the top of the heating tank; the liquid inlet of the mixed liquid pump is located on the side wall of the mixing chamber of the mixed liquid pump and is connected to the liquid outlet on the side wall of the heating tank; the mixed liquid outlet of the mixed liquid pump is connected to the liquid inlet at the bottom of the ammonia regeneration tank; the mixed liquid pump is equipped with a pressure relief port for the discharge of insoluble gas. The ammonia solution is heated at the bottom of the ammonia regeneration tank and then separated and regenerated. The regenerated ammonia is drawn into the combustion air flow by the gas ejector at the top of the ammonia regeneration tank and returned to the burner for repeated combustion.

2. The ammonia low-NOx immersion combustion device according to claim 1, characterized in that, The ammonia regeneration tank is equipped with a drain outlet at the bottom and is connected to a liquid pump to drain the liquid at the bottom of the ammonia regeneration tank and return it to the heating pool or discharge it.

3. The ammonia low-NOx immersion combustion equipment according to claim 1, characterized in that, The aeration mixture pump includes a housing, a motor, a drive shaft, a cam disc, a telescopic rod, and a spring check valve; the housing is provided with a partition barrier, with the upstream of the partition barrier being the aeration mixing zone and the downstream being the liquid outlet zone; The partition barrier has a cylindrical groove at its center for fixing the drive shaft. Several channels are provided on the partition barrier corresponding to the position of the telescopic rod for fixing the telescopic rod, and together with the hollow structure inside the telescopic rod, they form a sealed cavity for discharging the solution. One end of the telescopic rod is not in fixed contact with the cam disc, and the other end is connected to a spring check valve. Each spring check valve outlet is equipped with a reverse-flowing spring check valve for liquid backflow prevention. The portion of the drive shaft inside the housing has a through hole, and the middle section of the telescopic rod has a liquid inlet; the right side is a hollow structure.

4. The ammonia low-NOx immersion combustion device according to claim 3, characterized in that, The motor is located outside the housing and is fixedly connected to a cam disc located inside the housing via a drive shaft.

5. The ammonia low-NOx immersion combustion device according to claim 1, characterized in that, The heating pool has a closed structure, and a cover is provided at the top of the heating pool.

6. The ammonia low-NOx immersion combustion device according to claim 1, characterized in that, The inlet and outlet of the heat exchange tube bundle are respectively the liquefied natural gas inlet and the natural gas outlet.

7. The ammonia low-NOx immersion combustion equipment according to claim 1, characterized in that, The ammonia burner includes a burner housing and an inner burner nozzle; the top of the burner housing is connected to the fuel ammonia pipeline. The burner nozzle has an inner and outer two-layer structure. The inner layer has a regenerative catalytic cracking body arranged around the vertical axis. The regenerative catalytic body is an inverted frustum structure that gradually narrows from the top inlet to the middle section, and a cylindrical structure from the middle section to the bottom outlet. The burner nozzle has an outer layer structure arranged around the inner regenerative catalytic cracking body. The upper half of the outer layer structure is a cylindrical structure that gradually narrows from the middle to the bottom outlet. The outer side of the nozzle has a combustion air inlet and is connected to the combustion air pipeline.

8. The ammonia low-NOx immersion combustion device according to claim 7, characterized in that, The regenerative catalytic cracking body is filled with a uniform mixture of ceramic regenerative balls and ammonia cracking catalyst, and is wrapped with a metal fiber mesh on the outside.

9. The ammonia low-NOx immersion combustion device according to claim 7, characterized in that, A flue gas recirculation channel is provided between the inner side of the burner housing and the outer side of the burner nozzle, which is used to allow high-temperature flue gas to flow back to the burner nozzle to heat the heat storage catalytic cracking body.

10. A method for low-NOx immersion combustion of ammonia, wherein the ammonia low-NOx immersion combustion apparatus according to any one of claims 1-9 is used.

11. The ammonia low-NOx immersion combustion method according to claim 10, characterized in that, Includes the following: (1) The ammonia burner continues to burn under oxygen-deficient conditions. The high-temperature flue gas generated by the combustion forms a reflux zone in the flared section. Some of the high-temperature flue gas flows into the heat storage catalytic cracking body through the flue gas reflux channel, heating the internal heat storage body. The ammonia cracking catalyst cracks part of the passing ammonia gas into nitrogen and hydrogen. (2) The high-temperature flue gas generated by the combustion in step (1) is discharged into the heating pool by the flue gas distributor after passing through the flue. Most of the heat from the flue gas heats the material in the heat exchange tube bundle; a small part of the heat is conducted to the end of the flue and heats the liquid at the bottom of the ammonia regeneration tank. (3) Excess unburned ammonia gas reduces NOx produced by combustion to N2 during the flow of high-temperature flue gas. In addition, some of the unreacted ammonia dissolves in the water in the heating pool, and the other part exists in the upper part of the heating pool in gaseous form. The water produced by combustion is completely converted into liquid and mixed into the water in the heating pool, while nitrogen gas exists in the gaseous zone at the upper part of the heating pool with ammonia gas. (4) The liquid and gas in the heating tank are fed into the aeration mixing liquid pump through the liquid outlet pipe and the flue pipe, respectively, and are fully mixed inside, while the nitrogen gas is discharged through the pressure relief port; the fully mixed ammonia solution is fed into the ammonia regeneration tank through the mixed liquid output pipeline; (5) The ammonia solution from the heating tank and the aeration mixing liquid pump respectively is injected into the ammonia regeneration tank through the side inlet of the ammonia regeneration tank. The ammonia solution is heated at the bottom of the ammonia regeneration tank and then separated and regenerated. The regenerated ammonia is drawn into the combustion air flow by the ejector at the top of the ammonia regeneration tank and returns to the burner for repeated combustion with the combustion air flow.

12. The ammonia low-NOx immersion combustion method according to claim 11, characterized in that, The equivalence ratio of the ammonia burner is 1.05~1.2.

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