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CN-122015508-A - Double-heat-accumulating type heating furnace and method for ammonia gas hydrogen-doped combustion

CN122015508ACN 122015508 ACN122015508 ACN 122015508ACN-122015508-A

Abstract

The invention relates to a double-heat accumulating type heating furnace and a method for ammonia gas hydrogen-doped combustion, which belong to the technical field of heat accumulating type heating furnaces and comprise heat accumulating type burner systems, wherein a fuel channel/smoke channel and an air channel/smoke channel are symmetrically arranged on two sides of a heating furnace body, a first heat accumulating chamber filled with a fuel channel heat accumulator is arranged in the fuel channel/smoke channel, a second heat accumulating chamber filled with an air channel heat accumulator is arranged in the air channel/smoke channel, an air supply system is connected with the fuel channel/smoke channel and the air channel/smoke channel through a reversing system, ammonia fuel and combustion air are alternately introduced, a smoke discharging system is connected with the fuel channel/smoke channel and the air channel/smoke channel through the reversing system, and smoke is alternately discharged, and an ammonia decomposition catalyst layer is loaded in the first heat accumulating chamber. The invention utilizes the waste heat of the flue gas to drive the ammonia to crack and prepare the hydrogen, and realizes the stable combustion and low nitrogen emission of the ammonia-hydrogen mixed fuel, thereby realizing the energy conservation and emission reduction of the industrial kiln.

Inventors

  • HU XIANZHONG
  • WANG FENGJUAN
  • LI YAOHUI

Assignees

  • 东北大学

Dates

Publication Date
20260512
Application Date
20260226

Claims (10)

  1. 1. The utility model provides a two regenerative heating furnaces that ammonia was added hydrogen and is burnt which characterized in that includes: the regenerative burner system comprises a fuel channel/flue gas channel and an air channel/flue gas channel, wherein the fuel channel/flue gas channel and the air channel/flue gas channel are symmetrically arranged at two sides of a heating furnace body; The air supply system is connected with the fuel channel/flue gas channel and the air channel/flue gas channel through the reversing system and is used for alternately introducing ammonia fuel and combustion air; The smoke discharging system is connected with the fuel channel/smoke channel and the air channel/smoke channel through the reversing system and is used for alternately discharging smoke; The first heat accumulation chamber is internally loaded with an ammonia decomposition catalyst layer which is used for heating a fuel channel heat accumulator and the ammonia decomposition catalyst layer by utilizing the residual heat of the flowing flue gas, and after reversing, the flowing ammonia fuel is partially catalytically cracked to generate hydrogen so as to form ammonia-hydrogen mixed fuel.
  2. 2. The dual regenerative furnace for ammonia gas doped combustion of claim 1, wherein said ammonia decomposing catalyst layer is supported on the surface of the heat accumulator of the fuel passage.
  3. 3. The dual regenerative furnace for ammonia gas doped combustion of claim 1, wherein the catalyst of said ammonia decomposing catalyst layer comprises at least one of a noble metal catalyst, a non-noble metal catalyst, a bimetallic catalyst, a carbide catalyst or a nitride catalyst.
  4. 4. The dual regenerative heating furnace for ammonia gas hydrogen-doped combustion of claim 1, wherein the fuel channel heat accumulator and the air channel heat accumulator are made of honeycomb ceramics or ceramic heat accumulator balls.
  5. 5. The dual regenerative furnace for ammonia gas-doped combustion of claim 1, wherein the gas supply system comprises an ammonia fuel supply pipeline and an air supply pipeline, which are respectively connected with the corresponding fuel channel/flue gas channel and air channel/flue gas channel through an inner reversing valve and an outer reversing valve.
  6. 6. A combustion control method of a double-regenerative heating furnace based on ammonia gas hydrogen-doped combustion as claimed in any one of claims 1 to 5, which is characterized by comprising the following steps: S1, a heat storage stage, namely, high-temperature flue gas flows through a fuel channel/flue gas channel and an air channel/flue gas channel to store heat in a heat storage body; s2, in the cracking and preheating stage, ammonia fuel flows through the heated fuel channel heat accumulator loaded with the ammonia decomposition catalyst layer to form high-temperature ammonia-hydrogen mixed fuel; S3, in the hydrogen-adding combustion stage, the preheated ammonia-hydrogen mixed fuel and combustion air enter a hearth of a heating furnace to be mixed and combusted; and S4, in a cycle switching stage, the fuel channel/smoke channel and the air channel/smoke channel are alternately circulated between the functions of the fuel/air inlet channel and the smoke outlet channel by periodically switching the reversing system.
  7. 7. The method of claim 6, wherein in step S2, the control system adjusts the ammonia fuel inlet amount, and the reversing frequency is controlled to adjust the ammonia cracking rate, so that the volume percentage of hydrogen in the mixed fuel entering the hearth of the heating furnace is maintained between 10% and 25%.
  8. 8. The combustion control method according to claim 6, wherein in step S2, the ammonia-hydrogen mixed fuel is preheated to 600 ℃ or higher.
  9. 9. The method of claim 6, wherein during the switching in step S4, when the fuel passage/flue gas passage as the fuel inlet passage is switched to the flue gas outlet passage before the switching, the residual ammonia gas in the interior and the nitrogen oxides in the high-temperature flue gas undergo a selective non-catalytic reduction reaction to reduce the concentration of the nitrogen oxides in the flue gas.
  10. 10. The method of claim 6, wherein the temperature of the flue gas discharged from the flue gas discharge system is controlled to be 150 ℃.

Description

Double-heat-accumulating type heating furnace and method for ammonia gas hydrogen-doped combustion Technical Field The invention belongs to the technical field of regenerative heating furnaces, and particularly relates to a double regenerative heating furnace and a method for ammonia hydrogen-doped combustion. Background Although hydrogen (H 2) is a zero-carbon fuel, the problem of low volume energy density and poor storage and transportation safety exists, and the large-scale industrial application of the hydrogen is limited. Ammonia (NH 3) is used as a carbon-free energy carrier, and has become a hot spot for replacing coal and gas fuel in high energy consumption industries such as metallurgy because of its high hydrogen mass content of 17.7%, easy liquefaction and storage and transportation (9.2 bar can be liquefied at normal temperature) and complete industrial chain support. Meanwhile, the combustion products of ammonia are only water and nitrogen, which is a key path for realizing zero carbon emission in the industrial heating process. The use of ammonia fuel in the furnace can greatly reduce carbon emissions from metallurgical enterprises. However, the combustion performance of ammonia is poor compared with conventional fuels such as natural gas, and the direct application of ammonia in industrial kilns is limited. The ignition temperature of ammonia is extremely high (651 ℃) and the flame propagation speed is only about 0.07 m/s, which propagation speed is only 1/5 of that of methane. Because of the difficult ignition, lower heat value and narrow flammable range, under the working conditions of large space and high load of an industrial heating furnace, the phenomena of difficult ignition, flame off-target, even accidental flameout and the like are very easy to occur when pure ammonia burns, and the continuity of the heating process and the uniformity of a temperature field are difficult to maintain. In order to solve the problem of unstable ammonia combustion, the existing solution thinking is to increase combustion stability by adding high-heat-value hydrocarbon fuel such as hydrogen or natural gas. This solution often requires the additional introduction of a fuel of high heating value and can result in additional carbon emissions. For low-calorific-value fuel such as pure ammonia fuel, the present inventors have proposed to improve combustion reaction stability by using regenerative high-temperature air combustion technology (HTAC) which is widely used in industry. The heat accumulating type high temperature air combustion technology recovers the waste heat of flue gas through a heat accumulator, preheats the combustion improver or fuel to high temperature, utilizes physical sensible heat to improve the reaction activity, and can indeed improve the ignition performance of ammonia and stabilize flame. However, in the case of nitrogen-containing Fuel (Fuel-N), such as ammonia, nitrogen element in ammonia molecules is extremely easily oxidized in a high-temperature, oxygen-rich environment formed by regenerative combustion, and the amount of Fuel-type NOx produced increases exponentially. Therefore, although the traditional heat accumulating technology solves the problem of difficult ignition, serious NOx emission exceeding standard is necessarily caused, and the contradiction between stable combustion and low nitrogen is formed. Therefore, there is a need to solve the dilemma that ammonia combustion stability is poor and NOx emissions are high. Disclosure of Invention Aiming at the defects of the prior art, the invention provides the double-heat-accumulating type heating furnace for ammonia gas hydrogen-doped combustion and the method thereof, which utilize the waste heat of flue gas to drive ammonia gas to crack and prepare hydrogen, realize stable combustion and low nitrogen emission of ammonia-hydrogen mixed fuel, thereby realizing energy conservation and emission reduction of an industrial furnace. A dual regenerative heating furnace for ammonia gas hydrogen-doped combustion, comprising: the regenerative burner system comprises a fuel channel/flue gas channel and an air channel/flue gas channel, wherein the fuel channel/flue gas channel and the air channel/flue gas channel are symmetrically arranged at two sides of a heating furnace body; The air supply system is connected with the fuel channel/flue gas channel and the air channel/flue gas channel through the reversing system and is used for alternately introducing ammonia fuel and combustion air; The smoke discharging system is connected with the fuel channel/smoke channel and the air channel/smoke channel through the reversing system and is used for alternately discharging smoke; The first heat accumulation chamber is internally loaded with an ammonia decomposition catalyst layer which is used for heating a fuel channel heat accumulator and the ammonia decomposition catalyst layer by utilizing the residual heat of the flowing flue gas, and a