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CN-121988230-A - Ammonia catalytic cracker, low-nitrogen combustion equipment and combustion method

CN121988230ACN 121988230 ACN121988230 ACN 121988230ACN-121988230-A

Abstract

The invention discloses an ammonia catalytic cracker. The cracker comprises a shell and a corrugated coil pipe in the shell, wherein a separation blind plate is arranged in the shell and parallel to the bottom surface to separate the inner space into an upper half area and a lower half area, the corrugated coil pipe repeatedly penetrates through the separation blind plate, a pipe section of the corrugated coil pipe above the separation blind plate is filled with ammonia catalytic cracking catalyst, the pipe section of the corrugated coil pipe below the separation blind plate is not filled, an air inlet and an air outlet are respectively arranged at two sides of the upper half area, a flue gas inlet and a flue gas outlet are respectively arranged at two sides of the lower half area, wherein the air inlet is on the same side as the flue gas outlet, the air outlet is on the same side as the flue gas inlet, the corrugated coil pipe inlet is connected with an ammonia pipeline, and the outlet is connected with a cracking gas pipeline. The invention uses the ammonia cracking catalyst to pre-crack part of ammonia, uses the waste heat of flue gas to provide heat for the cracking reaction in the corrugated coil pipe, realizes the adjustment of the combustion property of fuel gas, and provides possibility for reducing fuel NOx.

Inventors

  • ZHAO YUNFENG
  • ZENG XIANGYU
  • WANG HUI
  • ZHOU HONGXIA

Assignees

  • 中国石油化工股份有限公司
  • 中石化（大连）石油化工研究院有限公司
  • 中国石化塔河炼化有限责任公司

Dates

Publication Date
20260508
Application Date
20241101

Claims (19)

  1. 1. An ammonia catalytic cracker is characterized by comprising a shell and a corrugated coil pipe positioned in the shell; The inside of the shell is parallel to the bottom surface and provided with a separation blind plate for separating the inner space of the ammonia catalytic cracker into an upper half area and a lower half area; the pipe section of the corrugated coil above the separation blind plate is filled with an ammonia catalytic cracking catalyst, and the pipe section of the corrugated coil below the separation blind plate is not filled; The shell is provided with an air inlet and an air outlet at two sides of an upper half area respectively, and is provided with a smoke inlet and a smoke outlet at two sides of a lower half area respectively, wherein the air inlet is on the same side as the smoke outlet, and the air outlet is on the same side as the smoke inlet, so that the flow direction of air is opposite to the flow direction of smoke; the inlet of the corrugated coil pipe is connected with an ammonia gas pipeline, and the outlet of the corrugated coil pipe is connected with a pyrolysis gas pipeline.
  2. 2. The ammonia catalytic cracker of claim 1 wherein at least one group of corrugated coils is provided, and more than two groups of corrugated coils are disposed in parallel within the catalytic cracker housing.
  3. 3. The ammonia catalytic cracker of claim 1 wherein the corrugated coil is sealed and positioned at a location where it penetrates the separation blind plate.
  4. 4. An ammonia catalytic cracker as defined in claim 1 wherein said corrugated coil is in the form of a flat tube.
  5. 5. The ammonia catalytic cracker of claim 1 wherein porous metal felt mesh is used to isolate the upper and lower sections of the corrugated coil to ensure gas passage while preventing catalyst particles from falling.
  6. 6. An ammonia low-nitrogen combustion device, characterized in that the ammonia catalytic cracker of any one of claims 1 to 5 is applied.
  7. 7. An ammonia low nitrogen combustion device as defined in claim 6, comprising: the air preheater is used for preheating air by taking the exhaust smoke of the boiler as a heat source; the ammonia catalytic cracker takes the flue gas discharged by the boiler as a heat source, heats ammonia passing through a corrugated coil in the ammonia catalytic cracker, and cracks at least part of the ammonia into hydrogen and nitrogen; The first-stage membrane separation equipment is used for receiving a pyrolysis product of the ammonia catalytic cracker as raw gas and separating the raw gas into first-stage permeation gas and first-stage residual gas; The second-stage membrane separation device takes the first-stage off-gas as raw gas and separates the raw gas into second-stage permeation gas and second-stage off-gas; the combustion boiler takes combustion air preheated by the air preheater, first-stage permeation air and second-stage permeation air as raw material gas, and performs catalytic combustion in the raw material gas, and comprises a combustor and a heat-taking device positioned in a hearth.
  8. 8. An ammonia low nitrogen combustion device according to claim 7, further comprising a mixer for mixing the first stage permeate gas and the second stage permeate gas to obtain a mixed permeate gas.
  9. 9. The ammonia low nitrogen combustion device of claim 7, further comprising a combustion fan and a smoke exhaust fan.
  10. 10. An ammonia low nitrogen combustion device according to claim 7, wherein the first stage membrane separation device incorporates a hydrogen separation membrane and the second stage membrane separation device incorporates an ammonia separation membrane.
  11. 11. The ammonia low nitrogen combustion apparatus of claim 8 wherein the inlet of the burner is connected to the gas mixer outlet and the combustion air outlet of the air preheater, the burner outlet being in communication with the boiler furnace.
  12. 12. The ammonia low nitrogen combustion device of claim 7, wherein the flue gas outlet of the combustion boiler is divided into two paths, the first path of flue gas outlet is connected with the flue gas inlet of the air preheater, and the second path of flue gas outlet is connected with the flue gas inlet of the ammonia catalytic cracker.
  13. 13. An ammonia low nitrogen combustion method, characterized in that the ammonia low nitrogen combustion apparatus according to any one of claims 6 to 12 is applied.
  14. 14. The ammonia low nitrogen combustion process of claim 13, comprising the steps of: (1) Introducing fuel ammonia into an ammonia catalytic cracker, and cracking part of the ammonia into hydrogen and nitrogen under the actions of flue gas heating and an ammonia cracking catalyst, wherein the cracked gas and the uncleaved ammonia together form a cracking mixed gas; (2) Introducing the cracked mixed gas into first-stage membrane separation equipment, allowing hydrogen to permeate through the first-stage membrane separation equipment as permeate gas, and allowing the mixed gas of nitrogen and ammonia to pass through second-stage membrane separation equipment as retentate gas; (3) And (2) fully mixing the hydrogen and the ammonia gas obtained in the step (2), leading the mixture to a combustor as mixed fuel gas, fully burning the mixed fuel gas in a hearth, fully exchanging heat between one strand of discharged hot flue gas and combustion air through an air preheater, preheating the combustion air, and then evacuating the combustion air, and introducing the other strand of the combustion air into an ammonia catalytic cracker to provide heat for ammonia pyrolysis and then evacuating the combustion air.
  15. 15. The ammonia low nitrogen combustion method according to claim 13, wherein the conversion rate of the fuel ammonia gas in the ammonia catalytic cracker in the step (1) is controlled to be 20-40%.
  16. 16. The ammonia low nitrogen combustion method of claim 13, wherein the reaction zone temperature of step (1) is 150-300 ℃.
  17. 17. The ammonia gas low-nitrogen combustion method according to claim 13, wherein the hot smoke in the step (3) is divided into two paths after passing through a smoke exhaust fan, the first path accounts for 10-30% of the total amount of the smoke, and the second path accounts for 70-90% of the total amount of the smoke.
  18. 18. The ammonia low nitrogen combustion process of claim 13 wherein in step (3) both flue gas empties at a temperature of not less than 85 ℃.
  19. 19. The ammonia low nitrogen combustion method according to claim 13, wherein the total pressure of the ammonia pipeline is not lower than 1 MPa before the ammonia gas in the step (1) is introduced into the ammonia catalytic cracker.

Description

Ammonia catalytic cracker, low-nitrogen combustion equipment and combustion method Technical Field The invention belongs to the technical field of heat energy engineering, and particularly relates to equipment and a method for mixed combustion of hydrogen production by ammonia pyrolysis. Background At present, how to solve global warming caused by exceeding of greenhouse gas emission has become a common problem for all people. While the major CCUS technologies are limited by their not yet fully matured, finding a "carbon-free" fuel to replace existing fossil fuels has become a new focus of carbon reduction technology research. Ammonia fuel has received a great deal of attention in recent years as a carbon-free clean fuel. Ammonia fuel has a high energy density up to 13.6 gj.m -3, which is almost three times that of hydrogen gas, and the hydrogen storage amount of ammonia is more up to 17.7 (wt)%, compared to another clean fuel hydrogen gas, so ammonia is considered to be a 2.0 version of hydrogen energy. Besides the characteristics of clean running and high hydrogen storage capacity of the hydrogen energy, the ammonia energy can be converted into liquid state only at-33 ℃ under normal pressure, and the explosion limit range of ammonia is narrower, so that compared with the hydrogen energy, the storage and transportation cost is greatly reduced, and the safety of the use process is improved. While ammonia energy sources have significant times compared to other fossil fuels and hydrogen energy at the point of discharge and storage, there are still problems in the combustion of ammonia. In addition, since ammonia molecules contain nitrogen, a large amount of fuel NOx is formed in the combustion process, and the ammonia gas is difficult to meet the combustion requirement as a single fuel due to the disadvantages, so that the development of ammonia energy sources is limited. The hydrogen gas is complementary to the ammonia gas in ignition and combustion properties, and is CO 2 -free fuel is not generated in the combustion process, so that the combustion by mixing the two materials is considered to be a viable scheme for ammonia energy utilization. Patent CN112984508B discloses a low nitrogen swirl burner that can achieve ammonia-hydrogen blending combustion. The burner comprises a windshield, and a primary cyclone burner and a secondary cyclone burner which are coaxial are arranged in the windshield. The primary cyclone burner is positioned at the axis position, takes ammonia with low hydrogen proportion as fuel, and the secondary burner is positioned at the outer ring of the primary burner, and takes pure ammonia as fuel. The primary swirl burner comprises a primary fuel nozzle, wherein the center of the primary fuel nozzle is a primary hydrogen fuel nozzle, and a plurality of primary ammonia fuel nozzles are uniformly arranged around the primary hydrogen fuel nozzle. The peripheral periphery of the primary fuel nozzle is uniformly provided with double swirl vanes. The secondary combustor comprises a plurality of secondary combustion pipes which are uniformly distributed on the outer circumference of the primary combustor. Although the combustor can realize the mixed combustion of ammonia and hydrogen, the fuel is binary mixed, the requirement for hydrogen cannot be eliminated, and high requirements are set for the supply of the fuel. CN110440251a discloses a control method of ammonia combustion and an ammonia combustion device. The ammonia combustion device comprises combustion equipment and ammonia cracking equipment, and hydrogen required in the ammonia combustion process can be provided through the ammonia cracking equipment. Although the method solves the problem of hydrogen supply in the combustion process and simplifies the energy source transmission, N 2 generated by ammonia pyrolysis is also introduced into the combustion device along with hydrogen, which may further aggravate the defect of NOx emission and cause the phenomenon of exceeding NOx emission. Disclosure of Invention Aiming at the problems in the prior art, the invention aims to provide ammonia low-nitrogen combustion equipment and method. According to a first object of the present invention, there is provided an ammonia catalytic cracker. Specifically, the ammonia catalytic cracker of the present invention has the following structure: The ammonia catalytic cracker comprises a shell and a corrugated coil pipe positioned in the shell; The inside of the shell is parallel to the bottom surface and provided with a separation blind plate for separating the inner space of the ammonia catalytic cracker into an upper half area and a lower half area; the pipe section of the corrugated coil above the separation blind plate is filled with an ammonia catalytic cracking catalyst, and the pipe section of the corrugated coil below the separation blind plate is not filled; The shell is provided with an air inlet and an air outlet at two sides of an upper ha