Ammonia-coal mixed combustion test system and multi-working condition operation method thereof

Abstract

The application discloses a kind of ammonia coal mixed combustion test system and its multi-working condition operation method.Belongs to fuel clean combustion technical field, including the experimental furnace body with main combustion zone, reduction zone and burn-out zone, and adjustable center ammonia pipe coaxially arranged in the center of burner;The center ammonia pipe is provided with axial telescopic adjusting mechanism and detachable spray head, and the position of nozzle can be continuously adjusted from main combustion zone to reduction zone.System is equipped with coal gasification chamber and multi-fuel feeding unit, and can independently supply pulverized coal, volatile matter, coal coke and ammonia respectively.The application realizes the staged and zoned reaction simulation of pulverized coal, volatile matter, coal coke and ammonia by decoupling the pyrolysis and combustion process of coal, can carry out three experimental modes of coal and ammonia mixed combustion, volatile matter and ammonia homogeneous phase reaction, coal coke and ammonia heterogeneous phase reaction, and has multiple operation control functions.Provides a compact structure, strong working condition adaptability test platform for in-depth study of ammonia coal mixed combustion mechanism and optimization of low-nitrogen combustion process.

Description

Technical Field

[0001] This invention belongs to the field of clean fuel combustion technology, specifically relating to an ammonia-coal mixed combustion test system and its multi-condition operation method. Background Technology

[0002] Ammonia, as a carbon-free fuel, has become a highly anticipated alternative energy source due to its high hydrogen content, lack of carbon, and sustainable production via the Haber-Bosch process. Compared to carbonaceous fuels, ammonia combustion does not produce carbon dioxide, and hydrogen transportation and storage are easier. However, ammonia's low flame velocity, low calorific value, and low flammability pose challenges to its combustion applications.

[0003] To improve the combustion characteristics of ammonia, co-firing it with coal is considered an effective approach, especially beneficial for the retrofitting of existing coal-fired power plants. However, due to the significant differences in combustion characteristics between ammonia and coal, direct co-firing easily generates large amounts of fuel-type nitrogen oxides and faces problems such as combustion instability. Studies have shown that the effectiveness of ammonia / coal co-firing is affected by factors such as the ammonia-to-coal ratio, injection position, nozzle direction, air staging, coal quality, and oxygen concentration. However, current research has not yet provided an effective experimental device and method for systematically studying the co-firing mechanism and optimizing low-NOx combustion processes. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an ammonia-coal co-combustion test system and its multi-condition operation method. This system decouples the coal pyrolysis and gasification process from the combustion process, enabling the sequential reaction of ammonia with different components in the coal, thus providing an experimental platform for studying the ammonia-coal co-combustion mechanism and optimizing low-NOx combustion processes.

[0005] A further technical problem to be solved by the present invention is to provide a multi-condition operation method for an ammonia-coal mixed combustion test system.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A test system for the co-combustion of ammonia and coal includes a burner, a test furnace body, a tail flue, a ash storage chamber, an adjustable central ammonia pipe, a flame monitoring device, a flue gas sampling and analysis device, an ash and slag sampling and analysis device, a storage and feeding unit, and a feedback control unit.

[0008] The burner includes a primary air duct, a pulverized coal concentrator, a secondary air duct, and a cyclone separator. The experimental furnace body includes a main combustion zone, a reduction zone, a burnout zone, and a burnout air inlet. The adjustable central ammonia pipe includes an axial telescopic adjustment mechanism and a detachable nozzle. The storage and feeding unit includes a pulverized coal chamber, a pulverized coal feeding unit, a volatile matter chamber, a volatile matter feeding unit, a coke chamber, a coke feeding unit, an ammonia storage chamber, an ammonia feeding unit, a preheated air chamber, an air feeding unit, and a coal gasification chamber.

[0009] The burner is located at the top of the furnace body and is introduced into the furnace through a primary air duct (coal powder, volatile matter, coke, etc.), a secondary air duct (swirling secondary air), and an adjustable central ammonia duct (variable ammonia flow).

[0010] The experimental furnace body is covered with a refractory insulation layer, and the burnout zone includes multiple equally shaped burnout air inlets at different furnace heights.

[0011] The tail flue is located below the experimental furnace body and discharges the exhaust gas generated after mixed combustion.

[0012] The slag chamber is located at the bottom of the furnace body and is used to collect solid particles that cannot be or are not completely burned.

[0013] The adjustable central ammonia tube is coaxially positioned at the center of the main burner. The central ammonia tube is connected to an axial telescopic adjustment mechanism, enabling continuous adjustment of the nozzle height within the furnace. A graphite packing seal is installed at the junction of the burner top and the adjustable central ammonia tube, connecting to a cooling air ring cavity. Primary air cools and seals the outer wall of the ammonia tube, preventing high-temperature flue gas from backflowing and burning the nozzle, while simultaneously preheating the ammonia gas.

[0014] The axial telescopic adjustment mechanism is a screw-driven mechanism or an electric push rod, and the adjustment range covers the height range from the main combustion zone to the reduction zone in the furnace; the detachable nozzle is threadedly connected to the nozzle end of the adjustable central ammonia pipe, including direct injection type, swirl type and multi-hole type.

[0015] The flame monitoring devices are respectively installed in the main combustion zone, reduction zone, and burnout zone on the experimental furnace body to monitor the mixed combustion state of each zone and transmit it to the feedback control unit.

[0016] The flue gas sampling and analysis device is installed on the tail flue to sample and analyze the composition of the exhaust gas.

[0017] The ash and slag sampling and analysis device is installed on the slag chamber to sample and analyze the composition of the slag.

[0018] The pulverized coal chamber and pulverized coal feeding unit send pulverized coal into the primary air duct inside the burner via primary air.

[0019] The coal gasification chamber is a fixed-bed reactor with a temperature of 500-900℃ and an atmosphere of nitrogen or oxygen-deficient gas, which separates pulverized coal into volatiles and char.

[0020] The volatile matter chamber and volatile matter feeding unit feed volatile matter into the primary air duct inside the burner; the volatile matter feeding unit includes a flame arrester and a Venturi mixer, which uses the negative pressure generated by the Venturi effect to stably draw in volatile matter and prevent gas backflow into the volatile matter chamber caused by positive pressure fluctuations in the primary air.

[0021] The coal and coke chamber and the coal and coke feeding unit send coal and coke into the primary air duct of the burner via primary air.

[0022] The ammonia storage chamber and ammonia feeding unit deliver ammonia fuel into the adjustable central ammonia pipe inside the burner.

[0023] The preheated air chamber and air feeding unit respectively feed a certain amount of air into the primary air duct, secondary air duct and burnout air inlet, serving as primary air, secondary air and burnout air.

[0024] The feedback control unit is connected to the flame monitoring device, flue gas sampling and analysis device, and ash and slag sampling and analysis device, and receives their signals. Based on the signal results, the operator outputs commands through the feedback control unit to change the state of the adjustable central ammonia pipe and the storage and feeding unit, thereby adjusting the operating conditions inside the experimental furnace.

[0025] During operation, pulverized coal can be selectively fed directly into the primary air duct from the pulverized coal feeding unit, or fed into the coal gasification chamber to generate volatiles and coke, and then fed into the primary air duct from the corresponding feeding unit; ammonia is injected into the furnace from the ammonia feeding unit through the adjustable central ammonia pipe; air is fed from the preheated air chamber into the primary air duct, secondary air duct and burnout air inlet respectively.

[0026] The operation method of the above-mentioned ammonia-coal mixed combustion test system includes the following steps:

[0027] S1. Fuel preparation: Three fuel forms, namely raw coal powder, volatile matter gas and coal char, are prepared for different experimental schemes. Volatile matter gas is obtained by pyrolyzing coal powder in a coal gasification chamber at 600-800℃ under a nitrogen atmosphere. When the volatile matter is completely released, the remaining solid deposit is coal char.

[0028] S2. Fuel introduction: Powdered raw coal, volatile matter gas or coke is introduced into the furnace through the primary air duct; ammonia gas is introduced through the adjustable central ammonia pipe, and the extension length of the central ammonia pipe and the nozzle type are adjusted appropriately;

[0029] S3. Data Monitoring and Analysis: Real-time monitoring of NO through flue gas sampling and analysis devices. x By analyzing the concentrations of O2 and CO, combined with ash and slag samples, the combustion and emission characteristics under different parameters were studied.

[0030] Preferably, the feedback control unit performs the following automatic optimization steps:

[0031] S1. Set the ammonia flow rate and pulverized coal flow rate to be constant;

[0032] S2. Control the axial telescopic adjustment mechanism to drive the central ammonia pipe to move stepwise from the starting point (such as the top of the main combustion zone) to the end point (the bottom of the reduction zone);

[0033] S3. At each step position, pause for a preset time and record NO using a flue gas sampling and analysis device. x steady-state concentration value;

[0034] S4. Compare the NO values ​​at each position. x Concentration, plot "Ammonia injection location - NO" x Concentration curve;

[0035] S5. Automatically adjust the central ammonia pipe to NO. x Locate and lock the position corresponding to the lowest concentration point.

[0036] Preferably, the operating method includes the following three experimental modes:

[0037] Mode 1: Coal and ammonia co-firing experiment

[0038] Pulverized coal is introduced through the primary air duct, and the length of the adjustable central ammonia pipe is adjusted to the main combustion zone. Ammonia and pulverized coal are mixed and burned in the main combustion zone to study the overall combustion characteristics and NO2 of ammonia-coal co-firing. x Genesis patterns;

[0039] Mode 2: Experiment on the reaction of volatiles with ammonia

[0040] The volatile gas generated in the coal gasification chamber is introduced through the primary air duct, and the length of the adjustable central ammonia pipe is adjusted to the main combustion zone. The ammonia and volatile gas undergo a homogeneous reaction in the main combustion zone, which is used to study the interaction mechanism between ammonia and gaseous volatiles.

[0041] Mode 3: Coal char and ammonia reaction experiment

[0042] Coal and coke powder was introduced through a primary air duct, and the length of an adjustable central ammonia pipe was adjusted to the reduction zone. Ammonia gas was then injected into the reduction zone where coal and coke were concentrated. This method was used to study the heterogeneous reduction reaction mechanism of ammonia on the surface of coal and coke.

[0043] Preferably, the method further includes a dynamic adjustment step: adjusting the composition of the primary air pulverized coal derivative, the extension length of the central ammonia pipe, and the nozzle type according to research needs to simulate the reaction characteristics under different process conditions.

[0044] Preferably, the feedback control unit has a mode switching interlock function: when switching from pulverized coal mode to volatile matter mode, the pulverized coal feeding unit is first shut down and purged. After the residual concentration of pulverized coal in the primary air duct is lower than the lower explosive limit, the valve switch of the volatile matter feeding unit is opened, and the opening of the swirl nozzle of the central ammonia pipe is simultaneously increased to maintain flame stability.

[0045] Preferably, under a constant total ammonia quantity, the ammonia injection pipe at the control center reciprocates within a certain cycle (e.g., T=10min): during time period t1, it remains in the main combustion zone, injecting a portion of ammonia (participating in combustion), and during time period t2, it rapidly retracts to the reduction zone, injecting the remaining ammonia (as a reducing agent). By adjusting the duty cycle of t1 / t2, the effects of pulsed ammonia injection or dynamic staged ammonia injection on NO are studied. x The impact.

[0046] The beneficial effects of this invention are as follows:

[0047] (1) This invention integrates a coal gasification chamber with a multi-fuel channel burner and an adjustable central ammonia pipe to construct a multifunctional ammonia-coal co-combustion test platform. This system decouples the coal pyrolysis gasification process from the combustion process, and can separate pulverized coal into volatile matter and coke as needed and deliver them independently. It realizes the sequential reaction control of ammonia with different components in coal, and provides a hardware foundation for the systematic study of the ammonia-coal co-combustion mechanism.

[0048] (2) By setting an axial telescopic adjustment mechanism and an adjustable central ammonia pipe with detachable nozzles, the ammonia injection position can be continuously adjusted within the range from the main combustion zone to the reduction zone, and the injection flow pattern can be changed as needed. Combined with the independent supply of three fuel forms, namely pulverized coal, volatile matter, and coke, it can cover three experimental modes: ammonia-coal co-firing, homogeneous reaction of volatile matter and ammonia, and heterogeneous reaction of coke and ammonia, supporting comparative studies under multiple working conditions.

[0049] (3) By setting up the linkage between the feedback control unit and the flame monitoring device, flue gas sampling and analysis device, and ash and slag sampling and analysis device, the functions of automatic optimization of ammonia injection position, interlock protection of mode switching, and dynamic adjustment of pulse ammonia injection can be realized. This provides a research method for exploring the low-NOx combustion process in the ammonia-coal co-firing process. Moreover, the system structure design fits the actual operating conditions of industrial boilers. Its experimental results have reference value for the technical transformation of ammonia-coal co-firing in coal-fired power plants. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the ammonia-coal mixed combustion test system of the present invention.

[0051] Figure 2 This is a schematic diagram of the process flow and control principle of the ammonia-coal mixed combustion test system of the present invention.

[0052] The attached diagram is labeled as follows: 1-burner, 11-primary air duct, 12-pulverized coal concentrator, 13-secondary air duct, 14-cyclone separator, 2-experimental furnace body, 21-main combustion zone, 22-reduction zone, 23-burnout zone, 24-burnout air inlet, 3-furnace tail flue, 4-ash chamber, 5-adjustable central ammonia pipe, 51-axial telescopic adjustment mechanism, 52-detachable nozzle, 6-flame monitoring device, 7-flue gas extraction... 8-Sampling and analysis device for ash and slag, 9-Storage and feeding unit, 911-Powdered coal chamber, 912-Powdered coal feeding unit, 921-Volatile matter chamber, 922-Volatile matter feeding unit, 931-Coal and coke chamber, 932-Coal and coke feeding unit, 941-Ammonia storage chamber, 942-Ammonia feeding unit, 951-Preheated air chamber, 952-Air feeding unit, 96-Coal gasification chamber, 10-Feedback control unit. Detailed Implementation

[0053] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. However, the following embodiments are only for explaining the present invention, and the scope of protection of the present invention should include all the contents of the claims. Moreover, through the description of the following embodiments, those skilled in the art can fully implement all the contents of the claims of the present invention.

[0054] Example 1: Device Structure of Ammonia-Coal Co-combustion Test System

[0055] This embodiment provides a specific structure of an ammonia-coal mixed combustion test system.

[0056] Burner 1 is located at the center of the top of the furnace body. A pulverized coal concentrator 12 is installed inside the primary air duct 11; a secondary air duct 13 is coaxially arranged outside the primary air duct 11 and contains an axial vortex 14 with a vortex number of 1.2.

[0057] The experimental furnace body 2 has a furnace chamber divided axially from top to bottom into a main combustion zone 21, a reduction zone 22, and a burnout zone 23. The inner wall of the furnace chamber is constructed of high-alumina refractory material, and the outer wall is covered with aluminum silicate fiber insulation cotton as a refractory and heat-insulating layer. The burnout zone 23 has a layer of burnout air inlets 24 at multiple different heights, and inlets at different heights can be opened according to experimental needs.

[0058] An adjustable central ammonia pipe 5 is coaxially positioned at the center of the primary air duct 11. This central ammonia pipe is connected to an axial telescopic adjustment mechanism 51 driven by an electric push rod. The adjustment range covers the upper part of the main combustion zone to the lower part of the reduction zone, enabling continuous adjustment of the ammonia nozzle position within this range. The nozzle end is detachably mounted with a nozzle head via a threaded connection, including direct injection, swirl, and multi-hole types, which can be replaced according to different experimental requirements.

[0059] The gasification chamber 96 is a small fixed-bed reactor, heated electrically to maintain a temperature of 600-800℃. It is filled with pulverized coal and pyrolyzed using high-purity nitrogen as the pyrolysis atmosphere. The volatile matter produced during pyrolysis is directly connected to the volatile matter chamber 921 for storage via insulated pipelines; the remaining solid coal char after pyrolysis is collected in the char chamber 931 after cooling.

[0060] Both the pulverized coal feeding unit 912 and the coke feeding unit 932 employ independent screw feeders, which deliver the corresponding fuels into the primary air duct 11 via primary air. The volatile matter feeding unit 922 uses a mass flow controller to control the flow rate of volatile matter gas and mixes it into the primary air duct 11. The ammonia feeding unit 942 is supplied with gas from the ammonia storage chamber 941. The ammonia gas is depressurized and its flow rate is controlled by a mass flow controller before being sent into the adjustable central ammonia pipe 5. The air feeding unit 952 preheats the air in the preheating air chamber 951 to 80-150°C and sends it into the primary air duct 11, secondary air duct 13, and burnout air inlet 24 via independent fans and mass flow meters, respectively.

[0061] The flame monitoring device 6 includes quartz observation windows opened on the furnace walls corresponding to the main combustion zone 21, reduction zone 22, and burnout zone 23, as well as an industrial CCD camera and photoelectric sensor installed at the observation windows, for real-time acquisition of flame images and brightness signals.

[0062] The flue gas sampling and analysis device 7 includes a water-cooled sampling probe installed at the tail flue 3 of the furnace, and a Fourier transform infrared spectrometer gas analyzer connected to the probe, which is used to continuously measure the concentration of components such as CO, CO2, O2, NH3, and NO in the flue gas online.

[0063] The ash sampling and analysis device 8 includes an openable and closable ash hopper located at the bottom of the ash storage chamber 4 for collecting bottom ash for elemental analysis and XRD phase analysis.

[0064] The feedback control unit 10 adopts a DCS control system, which is connected to the flame monitoring device 6, the flue gas sampling and analysis device 7, and the ash and slag sampling and analysis device 8 and receives their signals. According to the signals, the operator outputs instructions through the feedback control unit 10 to adjust parameters such as the position of the adjustable central ammonia pipe 5, the feeding rate of each storage and feeding unit, and the air volume distribution, thereby adjusting the working conditions inside the experimental furnace.

[0065] During operation, pulverized coal can be directly fed into the primary air duct 11 by the pulverized coal feeding unit 912, or fed into the coal gasification chamber 96 to generate volatile matter and coke, and then fed into the primary air duct 11 by the volatile matter feeding unit 922 or the coke feeding unit 932 respectively; ammonia is injected into the furnace by the ammonia feeding unit 942 through the adjustable central ammonia pipe 5; air is fed into the primary air duct 11, the secondary air duct 13 and the burnout air inlet 24 by the air feeding unit 952 respectively.

[0066] Example 2: Multi-condition operation method of ammonia-coal co-combustion test system

[0067] The apparatus described in Example 1 was used to conduct experimental studies in three modes, with typical bituminous coal selected as the experimental fuel. The specific implementation steps for the three modes are as follows:

[0068] Mode 1: Coal and ammonia co-firing experiment

[0069] This model is used to study the overall combustion characteristics and NO content of ammonia-coal co-firing. x Genesis patterns.

[0070] The gasification chamber 96 is closed, and raw coal powder is injected into the furnace through the primary air duct 11 via the coal powder feeding unit 912 and carried by the primary air. The extension length of the adjustable central ammonia pipe 5 is adjusted to the range of the main combustion zone 21, and a direct injection or swirl nozzle is selected according to the mixing requirements. The ammonia feeding unit 942 is adjusted to achieve different ammonia blending ratios, such as 10%, 20%, and 30% of the total fuel calorific value. Air is staged and regulated through the air feeding unit 952 to ensure that the excess air coefficient of the main combustion zone 21 is less than 1.0, and burnout air is supplemented through the burnout air inlet 24 to achieve a total excess air coefficient of 1.2 in the furnace. The tail flue gas is monitored by the flue gas sampling and analysis device 7, and fly ash is sampled by the ash and slag sampling and analysis device 8 to obtain NO under different ammonia blending ratios. x Emission characteristics and burnout characteristics data.

[0071] Mode 2: Experiment on the reaction of volatiles with ammonia

[0072] This model is used to study the interaction mechanism between ammonia and gaseous volatiles.

[0073] Powdered raw coal is added to the gasification chamber 96 and pyrolyzed under a nitrogen atmosphere at 600-800℃. The volatile matter produced by pyrolysis is stored in the volatile matter chamber 921 and introduced into the primary air duct 11 via the volatile matter feeding unit 922, where it is carried into the furnace by the primary air. The extension length of the adjustable central ammonia pipe 5 is adjusted to the range of the main combustion zone 21, and a swirl-type nozzle is selected to enhance the mixing of ammonia and volatile matter. Other experimental conditions, such as the ammonia flow rate and total excess air coefficient, are kept consistent with those in Model 1. The NO obtained in this model... x The emission data were compared and analyzed with that of Model 1.

[0074] Mode 3: Coal char and ammonia reaction experiment

[0075] This model is used to study the heterogeneous reduction reaction mechanism of ammonia on the surface of coal char.

[0076] Coal char obtained from pyrolysis in Mode 2 was used as raw material. The coal char was injected into the furnace through primary air duct 11 via primary air feeding unit 932. The extension length of the adjustable central ammonia pipe 5 was adjusted to the range of reduction zone 22, and a multi-hole nozzle was selected to increase the uniformity of ammonia distribution in the reduction zone. Other experimental conditions, such as ammonia flow rate and total excess air coefficient, remained consistent with Modes 1 and 2. The effect of ammonia on NO in the presence of coal char was analyzed through tail gas monitoring. x The restoration effect.

[0077] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A test system for the mixed combustion of ammonia and coal, characterized in that, It includes a burner, experimental furnace body, adjustable central ammonia pipe, storage and feeding unit, and feedback control unit; The burner is located on the top of the experimental furnace body and includes a primary air duct, a coal powder concentrator located inside the primary air duct, a secondary air duct coaxially located outside the primary air duct, and a cyclone separator located inside the secondary air duct. The experimental furnace body includes a main combustion zone, a reduction zone, and a burnout zone arranged sequentially along the flue gas flow direction, and the burnout zone is provided with a burnout air inlet; The adjustable central ammonia tube is coaxially arranged at the center of the burner and includes an axial telescopic adjustment mechanism and a detachable nozzle. The axial telescopic adjustment mechanism is used to drive the adjustable central ammonia tube to extend and retract along the furnace body axially, so that the nozzle position can be continuously adjusted within the height range from the main combustion zone to the reduction zone. The storage and feeding unit includes a coal gasification chamber, a pulverized coal chamber and a pulverized coal feeding unit, a volatile matter chamber and a volatile matter feeding unit, a coke chamber and a coke feeding unit, and an ammonia storage chamber and an ammonia feeding unit. The coal gasification chamber is used to pyrolyze and separate pulverized coal into volatile matter and coke. Its volatile matter outlet is connected to the volatile matter chamber, and its coke outlet is connected to the coke chamber. The pulverized coal feeding unit, the volatile matter feeding unit, and the coke feeding unit are respectively connected to the primary air duct and are used to independently supply pulverized coal, volatile matter, and coke to the burner. The ammonia feeding unit is connected to an adjustable central ammonia pipe and is used to supply ammonia gas to the burner. The feedback control unit is connected to the flame monitoring device, flue gas sampling and analysis device, ash and slag sampling and analysis device, axial telescopic adjustment mechanism, and storage and feeding unit, respectively, and is used to receive monitoring signals and regulate the position of the adjustable central ammonia pipe and the supply status of each fuel.

2. The ammonia-coal mixed combustion test system according to claim 1, characterized in that, The axial telescopic adjustment mechanism is a screw drive mechanism or an electric push rod, and its adjustment stroke covers the furnace height range from the upper part of the main combustion zone to the lower part of the reduction zone; the top of the burner and the penetration point of the adjustable central ammonia pipe are provided with graphite packing seal and connected to a cooling air ring cavity, and the primary air delivered by the primary air pipe cools and seals the outer wall of the adjustable central ammonia pipe.

3. The ammonia-coal mixed combustion test system according to claim 1, characterized in that, The detachable nozzle is threadedly connected to the nozzle end of the adjustable central ammonia tube, and the nozzle is selected from one of the following: direct injection type, swirl type, or multi-hole type.

4. The ammonia-coal mixed combustion test system according to claim 1, characterized in that, The experimental furnace body is covered with a refractory insulation layer; the burnout zone is provided with multiple layers of burnout air inlets along the height of the furnace body, and each layer of burnout air inlets is symmetrically arranged around the circumference of the furnace body.

5. The ammonia-coal mixed combustion test system according to claim 1, characterized in that, The tail flue is equipped with a flue gas sampling and analysis device, and the ash and slag sampling and analysis device is equipped on the slag stacking chamber; the main combustion zone, reduction zone and burnout zone are respectively equipped with flame monitoring devices connected to the feedback control unit.

6. The ammonia-coal mixed combustion test system according to claim 1, characterized in that, The gasification chamber is a fixed-bed reactor with a temperature control range of 500-900℃ and an atmosphere of nitrogen or oxygen-deficient atmosphere; the volatile matter feeding unit includes a flame arrester and a Venturi mixer, and the Venturi mixer uses the negative pressure generated by the Venturi effect to draw volatile gas from the volatile matter chamber.

7. The ammonia-coal mixed combustion test system according to claim 1, characterized in that, The system also includes a preheated air chamber and an air feeding unit. The air feeding unit is connected to the primary air duct, the secondary air duct and the burnout air inlet, respectively, and is used to provide preheated primary air, secondary air and burnout air.

8. A multi-condition operation method for an ammonia-coal mixed combustion test system based on any one of claims 1-7, characterized in that, Includes the following steps: S1. Fuel preparation: Pulverized coal is pyrolyzed in a coal gasification chamber at 600-800℃ under a nitrogen atmosphere to obtain volatile gases and coal char. S2. Fuel introduction: One of the following is introduced into the furnace through the primary air duct: raw coal powder, volatile gas, or coke; ammonia gas is introduced through the adjustable central ammonia pipe, and the extension length and nozzle type of the central ammonia pipe are adjusted according to experimental requirements. S3. Data monitoring and analysis: Real-time monitoring of flue gas composition using flue gas sampling and analysis devices, combined with ash and slag sampling and analysis, to study combustion and emission characteristics under different parameters; In step S2, depending on the type of fuel introduced, the method includes three experimental modes: Mode 1: Raw coal powder is introduced from the primary air duct, and the length of the adjustable central ammonia pipe is adjusted to the main combustion zone for coal and ammonia co-firing experiments. Mode 2: Volatile gas is introduced from the primary air duct, and the length of the adjustable central ammonia pipe is adjusted to the main combustion zone for experiments on the homogeneous reaction of volatiles and ammonia. Mode 3: Coal coke powder is introduced from the primary air duct, and the length of the adjustable central ammonia pipe is adjusted to the reduction zone range for experiments on heterogeneous reaction between coal coke and ammonia.

9. The multi-condition operation method according to claim 8, characterized in that, The feedback control unit performs at least one of the following automatic and dynamic adjustments: Automatic optimization: The ammonia and pulverized coal flow rates are set constant. The axial telescopic adjustment mechanism drives the adjustable central ammonia pipe in a step-by-step movement, recording the NO levels at each position. x The concentration steady-state value is automatically adjusted to NO. x The location corresponding to the lowest concentration point has been locked. Mode switching interlock: When switching from pulverized coal mode to volatile matter mode, first shut down the pulverized coal feeding unit and purge it. After the residual concentration of pulverized coal in the primary air duct is lower than the lower explosive limit, turn on the volatile matter feeding unit. At the same time, increase the opening of the swirl nozzle of the adjustable central ammonia pipe to maintain flame stability. Dynamic operating condition simulation: Based on real-time feedback data from flame monitoring devices, flue gas sampling and analysis devices, and ash and slag sampling and analysis devices, the composition ratio of pulverized coal derivatives in the primary air, the extension length and nozzle type of the central ammonia pipe, and the air volume distribution in each area are adjusted in a coordinated manner to simulate the reaction characteristics under different process conditions.

10. The multi-condition operation method according to claim 8, characterized in that, The method also includes pulse ammonia injection control: under a constant total ammonia quantity, the adjustable central ammonia pipe is controlled to reciprocate within a set cycle. During the first period, a portion of ammonia is injected while the pipe remains in the main combustion zone; during the second period, the pipe retracts to the reduction zone and injects the remaining ammonia. The effect of dynamic staged ammonia injection on NO is studied by adjusting the duty cycle. x The impact.

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