An adiabatic combustion device and process for low heating value exhaust gases

Abstract

This invention discloses an adiabatic combustion device and process for low-calorific-value emissions. The device includes a combustion chamber shell with an outer periphery, a high-temperature combustion chamber inside which is connected, and a mixer installed at the bottom of the combustion chamber shell. A high-temperature flue gas mixer is connected to the top of the combustion chamber shell. In this invention, the device uses low-energy, low-temperature circulating gas to enter the adiabatic device for cooling, thus protecting the device itself. The separate connection between the burner and the high-temperature flue gas mixer ensures flame stability, a faster heating rate, and enhanced turbulence in the temperature field inside the furnace. The burner's structural design is primarily based on the volume, flow rate, and reaction time of the flue gas formed after the decomposition of the ultra-low calorific-value emissions, determining its diameter and length.

Description

Technical Field

[0001] This invention belongs to the field of ultra-low calorific value emission gas resource utilization technology, specifically involving an adiabatic combustion device and process for low calorific value emission gas. Its main application industries are coal chemical and petrochemical, and it can also be extended to energy, environmental protection, metallurgy, petroleum, chemical and other industrial fields. Background Technology

[0002] During the operation of coal chemical and petrochemical plants, various combustible waste gases are generated in different stages such as coal gasification, conversion, purification, and synthesis. Current technology involves collecting these waste gases, sending them to a flare system for combustion treatment, and then directly releasing them into the atmosphere. These combustible waste gases are collectively referred to as ultra-low calorific value (ULV) emissions. Furthermore, some ULV emissions, due to their low calorific value, cannot burn stably, resulting in excessive CO emissions during emission, polluting the environment and wasting energy. With increasing societal emphasis on environmental protection, direct emission of ULV emissions after combustion no longer meets current environmental requirements. This is because although combustion of ULV emissions can achieve non-toxic and harmless treatment, gases such as sulfur oxides after combustion still cause air pollution; and particulate matter not fully formed during combustion pollutes the surrounding environment after settling.

[0003] Ultra-low calorific value emissions are combustible, but their ultra-low calorific value makes them unsuitable for stable combustion. They can be burned (high-temperature oxidation) by a certain ultra-low calorific value treatment device to generate heat, thus turning ultra-low calorific value emissions into fuel resources for utilization.

[0004] Based on ultra-adiabatic (enthalpy) combustion technology for low-calorific-value gases, this device can be used to burn various low-calorific-value gaseous fuels, exhibiting superior emission indicators (low-NOx effect) and extremely high configuration scalability to meet the application needs of multiple industries and operating conditions. The combustion temperature is close to the theoretical adiabatic combustion temperature, which can broaden the lower limit of gas combustion, transforming "unsustainable combustion" into "sustainable combustion." This technology achieves safe, efficient, and stable combustion of low-calorific-value gases with a calorific value of 400 kcal / Nm3.

[0005] Limitations of existing technologies: Existing technologies only use direct combustion (the calorific value of the combustion gas must be above 650 kcal / Nm3), and direct treatment methods are limited by the thermal properties of the materials being treated. They cannot efficiently treat exhaust gases with a calorific value of 400–650 kcal / Nm3.

[0006] By optimizing the combustion method, such as increasing premixing, reaction contact, and contact activity; or by increasing the gas residence time to achieve better contact between the gas and the packing material, the high-temperature oxidation effect can be improved. This enhances the reaction efficiency of the technology and optimizes the equipment structure. However, existing technologies cannot achieve the energy release function of high-temperature oxidation. After the reaction, the gas will inevitably carry unburned substances (CO≥260ppm) from the outlet into subsequent equipment. Even after the contaminants and corrosive substances condense, the small droplets contain dissolved acidic gases, which can still cause corrosion and must be removed. The ultra-low calorific value emission gas ultra-insulated combustion device has a high-temperature oxidation energy release function, which can oxidize the effective components of low calorific value gas at high temperatures, improving its combustion rate. Simultaneously, in conjunction with subsequent systems, it can remove harmful substances such as acids, NOx, and dust. Summary of the Invention

[0007] The purpose of this invention is to provide an adiabatic combustion device and process for low-calorific-value emissions, achieving the functions of purifying ultra-low-calorific-value emissions and releasing energy through high-temperature oxidation. The high-temperature oxidation release is ensured by fully mixing super-insulating filler material and swirl premixing. Simultaneously, the energy of the low-temperature circulating gas at the inlet of the swirl absorption tube increases the gas flow rate and forces mixing with the high-temperature flue gas, improving the efficiency of high-temperature oxidation release. The fully mixed energy exchange achieves dust removal and gas purification; separating the energy exchange processes achieves the desired function.

[0008] To achieve the above objectives, the technical solution adopted by the present invention includes:

[0009] An adiabatic combustion device for low-calorific-value emissions comprises a burner and a high-temperature flue gas mixer connected sequentially from bottom to top; a combustion chamber shell is provided on the outer periphery of the burner, and a high-temperature combustion chamber is provided inside the burner and communicates with the high-temperature combustion chamber; a mixer is provided at the bottom of the combustion chamber shell; and the high-temperature flue gas mixer is connected to the top of the combustion chamber shell.

[0010] Optionally, the mixer is provided with a through pipe, with the fuel gas inlet and oxidant inlet connected from the left and right sides of the pipe respectively, and the downstream pipes of the two inlets converge to the front flow channel of the premixed gas flow guide; the outlet end of the premixed gas flow guide is directly connected to the radial fluid guide device.

[0011] Optionally, in the combustion chamber shell configuration, the skirt serves as the bottommost support structure, directly welded and fixed to the bottom flange of the combustion chamber shell; the support plate is horizontally mounted on the lower middle inner wall of the combustion chamber shell, providing installation support for the upper air distribution plate and buffer box; the pressure relief port extends outward from the upper middle part of the side wall of the combustion chamber shell, serving as the safe release interface for the cavity; the air jacket is an annular cavity wrapped between the outer wall of the high-temperature combustion chamber and the inner wall of the combustion chamber shell, with the inlet and outlet of the jacket respectively located on the side wall of the shell; temperature sensors and thermocouples are inserted into the cavity from different height positions on the side wall of the combustion chamber shell to complete multi-point temperature monitoring; the inspection port is located on the top inclined surface of the combustion chamber shell, directly connecting to the internal space of the high-temperature combustion chamber.

[0012] Optionally, in the high-temperature combustion chamber configuration, the premixed medium buffer tank is fixed above the support plate, with its inlet end directly connected to the outlet pipe of the mixer to receive the premixed combustible medium; the heat insulation and energy storage layer is completely attached to the inner wall of the high-temperature combustion chamber to form a complete heat insulation and energy storage lining; the igniter is inserted from the side opening of the combustion chamber shell and installed in the upper area of ​​the premixed medium buffer tank, aligned with the combustion ignition position; the air distribution plate is horizontally installed on the top of the premixed medium buffer tank, and the ventilation mesh is laid on the opening surface of the air distribution plate. The combination of the two distributes the medium in the buffer tank evenly upward into the combustion area.

[0013] Optionally, the high-temperature flue gas mixer is vertically connected to the top outlet of the high-temperature combustion chamber via a flange interface at the bottom; the low-temperature circulating air inlet is located at the top left interface of the high-temperature flue gas mixer, and the thermal inert gas outlet is located at the rightmost end face of the high-temperature flue gas mixer; the high-temperature flue gas inlet is connected to the upper left cavity of the high-temperature flue gas mixer, and the distributor is installed downstream of the high-temperature flue gas inlet to evenly disperse the incoming flue gas; the spray device is arranged horizontally in the downstream cavity of the distributor, and the swirl vanes are installed in the flow channel behind the spray section; the dust removal device is located at the rightmost end of the high-temperature flue gas mixer and in front of the thermal inert gas outlet. After the final gas-solid separation is completed, the clean conditioning gas is sent out from the outlet.

[0014] An adiabatic combustion process for low-calorific-value exhaust gas, utilizing any of the adiabatic combustion devices for low-calorific-value exhaust gas described in this invention, includes: The low-calorific-value fuel gas to be treated enters through the fuel gas inlet and mixes with the air introduced through the oxidant inlet. After being mixed and guided by the premixed airflow guide, the premixed gas is sent to the premixed medium buffer box through the radial fluid guide device. Then, it is sent to the upper heat insulation energy storage layer through multiple longitudinally stacked air distribution plates and air caps to preheat the gas to 150°C above the actual combustion temperature of the fuel medium. The low-temperature circulating air enters the high-temperature flue gas mixer through the low-temperature circulating air inlet. The medium-temperature thermal inert medium with a suitable temperature is sent to the downstream system through the thermal inert gas outlet.

[0015] Optionally, the process flow of the high-temperature flue gas mixer specifically includes: Low-temperature circulating air is introduced from the low-temperature circulating air inlet at the top, and mixes with the high-temperature flue gas from the high-temperature flue gas inlet. Under the action of the distributor, the mixed high-temperature flue gas is cooled down. After being cooled down, the mixed high-temperature flue gas is desulfurized and denitrified by the spray device, and then fully contacted by the swirl plate. After being treated by the dust removal device, it is discharged from the hot inert gas outlet at the tail end for use.

[0016] Optional, specifically including: First, high-calorific-value gas is introduced into the high-temperature combustion chamber as fuel, and ignition is performed using an igniter to raise the temperature in the opposite direction to the normal airflow, heating the heat insulation storage layer and the furnace body refractory material; during this period, the thermal inert gas outlet is closed. Once the temperature of the thermal storage layer is 150°C higher than the fuel reaction temperature and the temperature of the low-temperature preheating zone is 300°C lower than the combustion temperature, the supply of high-calorific-value fuel gas shall be stopped. After the low-calorific-value fuel gas and preheated air are fully premixed in the mixer, they flow through the air distribution plate into the high-temperature combustion chamber. The temperature of the combustion device is monitored in real time by thermocouples and temperature sensors installed on the combustion chamber shell. After the system is running stably, the thermal inert gas outlet is opened. The high-temperature flue gas flows to the high-temperature flue gas mixer at the top. The purified thermal inert gas is then discharged after cooling, denitrification, desulfurization, denitrification and dust removal.

[0017] Compared with the prior art, the advantages of the present invention include: This invention protects the device by cooling the low-temperature circulating gas that reduces energy before it enters the insulation device. The burner and the high-temperature flue gas mixer are connected separately, which can ensure flame stability, a faster heating rate, and enhance the turbulence of the temperature field inside the furnace. The burner structure design is mainly based on the amount, flow rate, and reaction time of the flue gas formed after the decomposition of the ultra-low calorific value exhaust gas to determine its diameter and length.

[0018] The burner employs ultra-insulated combustion technology to meet the requirements of multi-fuel operation, offering superior NOx emissions, high-speed flames, and improved furnace temperature uniformity. A unique burner control system ensures safe operation of the combustion unit during ignition, start-up, and shutdown. Its powerful heat transfer capability allows some of the heat generated by combustion to be transferred from the downstream high-temperature zone to the upstream low-temperature zone, preheating the unburned gas mixture and broadening the combustion range of low-concentration combustible gases. Pre-oxidation technology ensures stable combustion. Turbulent effects such as vortexing, splitting, and merging of gases within the porous medium enhance gas mixing and dispersion, significantly accelerating the combustion reaction and increasing the combustion rate. Attached Figure Description

[0019] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof: Figure 1 This is a schematic diagram of the ultra-low calorific value emission gas ultra-insulated combustion device of the present invention; 1-Mixer, 11-Fuel gas inlet, 12-Oxidant inlet, 13-Premixed gas flow guide, 14-Radial fluid flow guide device; 2-Combustion chamber shell, 21-Skirt, 22-Support plate, 23-Pressure relief port, 24-Air jacket, 25-Temperature sensor, 26-Thermocouple, 27-Inspection port; 3-High-temperature combustion chamber, 31-Premixed medium buffer box, 32-Insulated energy storage layer, 33-Igniter, 34-Air distribution plate, 341-Ventilation mesh; 4-High temperature flue gas mixer, 41-Low temperature circulating air inlet, 42-Hot inert gas outlet, 43-High temperature flue gas inlet, 44-Distributor, 45-Spray device, 46-Swirl vane, 47-Dust removal device; Figure 2 This is a detailed structural schematic diagram of the high-temperature flue gas mixer of the present invention; Figure 3 This is a schematic diagram of the air distribution plate structure of the present invention. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0021] Combination Figure 1The adiabatic combustion device for low-calorific-value emission gas of the present invention comprises a burner and a high-temperature flue gas mixer connected sequentially from bottom to top; a combustion chamber shell 2 is provided on the outer periphery, and a high-temperature combustion chamber 3 is provided inside the combustion chamber shell 2 and communicates with it; a mixer 1 is provided at the bottom of the combustion chamber shell 2; a high-temperature flue gas mixer 4 is connected to the top of the combustion chamber shell 2; the mixer 1 serves as the premixing core of fuel and oxidant, with fuel gas inlet 11 connected to fuel gas and oxidant inlet 12 connected to combustion medium, and the two fluids entering the premixed airflow guide 13 to complete full mixing, and then the premixed airflow is uniformly guided to the downstream combustion area through the radial fluid guide device 14 to avoid local uneven concentration causing combustion instability. The combustion chamber shell 2 is the external pressure-bearing and protective base of the entire combustion chamber: the skirt 21 serves as the bottom support structure, firmly fixing the entire device to the installation foundation; the support plate 22 provides installation support for the internal air distribution and energy storage components; the pressure relief port 23 serves as a safety protection component, automatically releasing pressure when the pressure inside the chamber exceeds the limit abnormally, preventing equipment damage; the air jacket 24 utilizes the waste heat of the combustion chamber to preheat the combustion air, improving thermal efficiency; the temperature sensor 25 and thermocouple 26 collect the temperature data inside the chamber in real time and feed it back to the control system to adjust the combustion conditions; the inspection port 27 provides an operating channel for the daily maintenance and ash removal of internal components. The high-temperature combustion chamber 3 is the core area where the fuel completes the combustion reaction: the premixed medium buffer box 31 temporarily stores the uniform premixed combustible medium and stably supplies it to the combustion area; the heat insulation and energy storage layer 32 reduces the heat loss of the chamber and maintains the high-temperature combustion environment, while also playing a role in heat insulation and protection; the igniter 33 outputs ignition energy to ignite the premixed combustible medium and start the combustion process; the air distribution plate 34, together with the ventilation net 341, distributes the combustion air evenly to the entire combustion section, ensuring uniform flame distribution and no local high-temperature areas. The high-temperature flue gas mixer 4 is used to condition and purify the high-temperature flue gas: the low-temperature circulating air inlet 41 receives low-temperature circulating air and mixes with the high-temperature flue gas to regulate the flue gas temperature; the hot inert gas outlet 42 transports the conditioned high-temperature inert gas to the downstream process section; the high-temperature flue gas inlet 43 receives the high-temperature flue gas from upstream and enters the cavity for subsequent treatment; the distributor 44 evenly distributes the airflow entering the cavity to avoid airflow deviation; the spray device 45 sprays washing liquid to remove particulate matter and soluble impurities from the flue gas; the swirl vane 46 enhances airflow disturbance, prolongs the contact reaction time between the flue gas and the washing liquid, and improves the purification effect; the dust removal device 47 finally captures the residual particulate matter in the flue gas to ensure that the cleanliness of the outlet flue gas meets the standards.

[0022] Specifically, including: The mixer 1 is configured such that the fuel gas inlet 11 and the oxidant inlet 12 are respectively connected to the cavity from the left and right sides of the mixer. The downstream pipelines of the two inlets converge to the front flow channel of the premixed airflow guide 13. The outlet end of the premixed airflow guide is directly connected to the radial fluid guide device 14. After the radial uniform distribution of the premixed airflow is completed, it is connected to the downstream high-temperature combustion chamber from the right outlet of the mixer.

[0023] The combustion chamber shell 2 is configured with a skirt 21 as the bottom support structure, which is directly welded and fixed to the bottom flange of the combustion chamber shell; the support plate 22 is horizontally mounted on the lower middle inner wall of the combustion chamber shell, providing installation support for the air distribution plate and buffer box above; the pressure relief port 23 extends outward from the upper middle part of the side wall of the combustion chamber shell, which is the safe venting interface of the cavity; the air jacket 24 is an annular cavity wrapped between the outer wall of the high-temperature combustion chamber and the inner wall of the combustion chamber shell, and the inlet and outlet of the jacket are respectively opened on the side wall of the shell; the temperature sensor 25 and the thermocouple 26 are inserted into the cavity from different height positions on the side wall of the combustion chamber shell to complete multi-point temperature monitoring; the inspection port 27 is opened on the top slope of the combustion chamber shell, which directly connects to the internal space of the high-temperature combustion chamber. The main structure of the combustion device of this invention adopts a dual temperature control scheme of composite refractory insulation lining and external air jacket film cooling: the static insulation control of the inner refractory insulation layer relies on the steady-state heat conduction theory of multi-layer composite lining to pre-calculate the thickness of the refractory layer and the insulation layer, and determines the lining structure with the furnace combustion temperature and outer wall temperature ≤80℃ as boundary conditions, forming the high-temperature combustion chamber 3 of this invention, which directly bears the high temperature of the furnace and blocks high-temperature radiation and heat conduction; the insulation layer greatly reduces the heat transfer to the outside, and achieves basic insulation by relying on the thermal resistance of the material itself, reducing the heat load transferred to the outside from the source. The dynamic film cooling of the air jacket is actively controlled: a sealed air jacket 24 is set on the outer wall of the furnace, and cold air is introduced into the jacket to form a continuous film cooling barrier on the outside of the furnace wall, which carries away the residual heat that leaks through the insulation layer. The dual-layer structure works in synergy: the refractory insulation lining undertakes the main heat insulation task, reducing the heat transferred to the furnace shell; the air jacket serves as a backup for dynamic temperature control, dealing with temperature anomalies caused by load fluctuations and local lining defects. The two work together to ensure that the outer wall of the furnace shell meets the temperature index of ≤80℃ for a long time.

[0024] A high-temperature combustion chamber 3 is set up, and a premixed medium buffer box 31 is fixed above the support plate 22. Its inlet end is directly connected to the outlet pipe of the mixer to receive the premixed combustible medium. The heat insulation energy storage layer 32 is completely attached to the inner wall of the high-temperature combustion chamber to form a complete heat insulation energy storage lining. The igniter 33 is inserted from the side opening of the combustion chamber shell and installed in the upper area of ​​the premixed medium buffer box, aligned with the combustion ignition position. The air distribution plate 34 is horizontally installed on the top of the premixed medium buffer box, and the ventilation net 341 is laid on the opening surface of the air distribution plate. The combination of the two distributes the medium in the buffer box evenly upward into the combustion area. The heat insulation energy storage layer 32 of this invention uses a porous ceramic material with two outstanding features: first, it has many pores and a large surface area, with the surface area of ​​1 cubic meter of material reaching thousands of square meters; second, it has a large heat capacity and can store a large amount of heat. When combustion begins, the porous material will quickly absorb the heat generated by combustion and lock it firmly in its own structure. Thermal cycle superenthalpy: making the exhaust gas "hot enough to spontaneously combust". The heat stored in the porous material is not wasted. It is transferred to the cold exhaust gas entering the combustion zone in two ways: thermal convection and thermal radiation. In this way, the cold exhaust gas is preheated to a certain temperature—far exceeding the limits of traditional combustion—before it even ignites; this state is called "superenthalpy." It has a strong heat transfer capacity, allowing some of the heat generated by combustion to be transferred from the high-temperature zone downstream to the low-temperature zone upstream, preheating the unburned mixture and widening the combustion range of low-concentration combustible gases. The use of pre-oxidation technology ensures a stable combustion process. The turbulent effects of vortexing, splitting, and merging of gases within the porous medium enhance gas mixing and dispersion, significantly accelerating the combustion reaction and increasing the combustion rate. The fully insulated, regenerative, and sealed furnace body results in extremely low heat loss. The multi-layered composite insulation and refractory structure blocks heat conduction and radiation from the furnace wall, reducing low-temperature heat loss from the outer wall by more than 35% compared to conventional incineration. Relying on the self-sustaining combustion of the exhaust gas's own combustible components, the low-calorific-value PSA desorbed gas does not require continuous supplementary combustion; only a small amount of auxiliary fuel is needed for start-up, significantly reducing gas operation costs. Regenerative preheating: "Preheating" the exhaust gas in advance.

[0025] The high-temperature flue gas mixer 4 is vertically connected to the top outlet of the high-temperature combustion chamber via a flange interface at the bottom; the low-temperature circulating air inlet 41 is located at the top left interface of the high-temperature flue gas mixer, and the thermal inert gas outlet 42 is located at the rightmost end face of the high-temperature flue gas mixer; the high-temperature flue gas inlet 43 is connected to the upper left cavity of the high-temperature flue gas mixer, and the distributor 44 is installed downstream of the high-temperature flue gas inlet to evenly disperse the incoming flue gas; the spray device 45 is arranged horizontally in the downstream cavity of the distributor, and the swirl vane 46 is installed in the flow channel behind the spray section; the dust removal device 47 is located at the rightmost end of the high-temperature flue gas mixer and in front of the thermal inert gas outlet. After the final gas-solid separation is completed, the clean conditioning gas is sent out from the outlet.

[0026] The specific work process is as follows: Ultra-low calorific value exhaust gas containing dust and acidic gases such as ammonia and hydrogen sulfide enters through fuel gas inlet 11 and mixes with air introduced through oxidant inlet 12. It is then mixed and guided by premixed airflow guide 13. The premixed gas is then sent to premixed medium buffer tank 31 via radial fluid guide device 14. It is then sent to the upper heat-insulating energy storage layer 32 via multiple longitudinally stacked air distribution plates 34 and air caps for preheating to 150°C above the actual combustion temperature of the fuel medium. After reaction with the insulation material, high-temperature flue gas is formed. The temperature is generally above 850℃; excessively high flue gas temperature can easily damage the metal structure of the downstream system. This structure mainly refers to: flue gas transport pipelines, valve groups, and flue gas analysis instruments. The recirculated air after energy release comes from: the generated high-temperature flue gas heating pulverized coal, cooling it, and releasing water vapor to form low-temperature flue gas, which is then sent to the mixing section by a circulating fan as a cooling medium and enters the high-temperature flue gas mixer 4 through the low-temperature circulating air inlet 41; a suitable medium-temperature thermal inert medium is formed and sent into the downstream system through the thermal inert gas outlet 42. Ultra-low calorific value exhaust gas flows from bottom to top, undergoing an oxidation reaction through the large contact area of ​​the high-temperature energy storage porous medium.

[0027] Top-mounted flue gas mixing and environmental treatment device: The top-mounted high-temperature flue gas mixer 4 integrates desulfurization, denitrification, and dust removal functions. The high-temperature flue gas generated by the burner has a temperature range of 780-960℃, which cannot be directly utilized as conventional metal materials cannot withstand it. Therefore, a high-temperature flue gas mixer 4 is installed. Low-temperature circulating air is introduced from the top low-temperature circulating air inlet 41 and mixes with the high-temperature flue gas from the high-temperature flue gas inlet 43. Under the action of the distributor 44, the mixed high-temperature flue gas is cooled down. After cooling, the mixed high-temperature flue gas is then sprayed by the desulfurization and denitrification liquid of the spray device 45 to remove sulfides and nitrogen oxides. After being fully contacted by the swirl vanes 46 for desulfurization and denitrification, it flows to the rear end and is treated by the dust removal device 47 before being discharged from the tail end through the hot inert gas outlet for reuse.

[0028] The adiabatic combustion process for low-calorific-value emission gas of the present invention specifically includes: 1. First, high-calorific-value gas is introduced into the high-temperature combustion chamber 3 as fuel, and ignition is performed by igniter 33 to raise the temperature in the opposite direction to the normal airflow, heating the heat insulation storage layer 32 and the furnace body refractory material; during this period, the hot inert gas outlet 42 is closed to prevent hot gas from leaking out. 2. After the temperature of the thermal storage layer 32 is 150°C higher than the fuel reaction temperature and the temperature of the low-temperature preheating zone is 300°C lower than the combustion temperature, the supply of high-calorific-value fuel gas shall be stopped. 3. After the low-calorific-value gas and preheated air are completely premixed in the mixer 1, they flow through the air distribution plate 34 into the high-temperature combustion chamber 3. The temperature is lower than the theoretical combustion temperature, which can increase the inlet enthalpy and increase the combustion temperature. However, oxidation reaction will not occur in this area. Since the low-temperature zone has already stored heat, the process of premixing the gas will absorb the heat of the low-temperature heat storage body, which will increase the inlet enthalpy value and facilitate the adiabatic combustion of the low-calorific-value gas. 4. The temperature of the combustion device is monitored in real time by thermocouples 26 and temperature sensors 25 installed on the combustion chamber shell 2. After the system is running stably, the thermal inert gas outlet 42 is opened according to the thermal requirements of the downstream system. The high-temperature flue gas flows to the high-temperature flue gas mixer 4 at the top. It is fully contacted by the distributor 44 and the swirl vanes 46 to improve the contact efficiency. At the same time, swirling dust removal is carried out, and the dust is periodically removed by the ash removal device. Finally, the purified thermal inert gas after cooling, denitrification, desulfurization, denitrification and dust removal is sent to the downstream system.

[0029] This invention's process is suitable for treating low-calorific-value exhaust gases and recovering residual energy from them. Due to their low thermal quality, the system heats the flue gas generated from combustion. It is applicable to the upgrading of pulverized coal gasification feedstock. The mixing section is an environmentally friendly integrated treatment device for combustion flue gas. The waste heat recovery device differs from a conventional heat exchanger; it uses pulverized coal gasification feedstock as the heat-absorbing material to recover the heat from the flue gas generated by the combustion of low-quality, low-calorific-value exhaust gases. The process feedstock is a water-containing solid feedstock that absorbs the exhaust heat from the adiabatic combustion device.

[0030] Example 1: The ultra-low calorific value emissions from a coal chemical plant, consisting of acidic gas, shift flash gas, and pressure swing adsorption tail gas, need to be treated by an ultra-low calorific value emissions ultra-insulated combustion device to generate high-temperature flue gas for the subsequent system operation.

[0031] Start-up and operation process of the unit: Ultra-low calorific value emission gas volume is 12000 Nm³ 3 / h, with an operational flexibility of 60%–120%. Design parameters: design pressure 1.1 MPa, design temperature 150℃.

[0032] The ultra-low calorific value (ULCV) emission gas ultra-insulated combustion device has an inner diameter of 49,000 mm, with ULCV emission gas inlet and outlet specifications of DN700 / DN1600, a circulating gas inlet size of DN1400, and a fuel gas pipeline specification of DN80. It contains four burners arranged in two circular rings, evenly distributed around the circumference. After treatment by the ultra-low calorific value emission gas ultra-insulated combustion device, the CO concentration in the flue gas is less than 200 ppm, and the oxygen content is 3.5%. After meeting these standards, the gas is sent to the downstream system for further treatment.

[0033] Operating process flow: 1. First, high-calorific-value gas is used as fuel for ignition and heating, which is opposite to the normal airflow direction, to heat the heat storage body and the furnace refractory material; during this period, the hot inert gas outlet valve group is used to prevent hot gas from leaking out.

[0034] 2. Once the temperature of the high-temperature regenerator is 150°C higher than the fuel reaction temperature, the temperature of the low-temperature preheating zone is higher than the premixed gas temperature but lower than the theoretical combustion temperature, which can increase the inlet enthalpy and increase the combustion temperature without causing oxidation reaction in this zone, and the temperature is 300°C lower than the combustion temperature, stop the operation of the supplementary heating and ignition burner.

[0035] 3. After the low-calorific-value gas is completely premixed with the preheated air, it enters the low-temperature zone at a temperature higher than that of the premixed gas but lower than the theoretical combustion temperature. This increases the inlet enthalpy and combustion temperature, and prevents oxidation reactions in this zone. Since the low-temperature zone has already stored heat, the flow of the premixed gas will absorb the heat of the low-temperature heat storage body, which will increase the inlet enthalpy value and facilitate the adiabatic combustion of the low-calorific-value gas.

[0036] Once the system is running stably, determine whether to start the supplementary heat burner based on the thermal requirements of the downstream system.

[0037] Gas volume processed: 12000 Nm 3 / h, 2000Nm 3 Replacing the original hot blast stove fuel with low-calorific-value gas per hour can avoid unnecessary heat loss and is expected to save 2000 Nm³. 3 The economic benefits generated by producing syngas per hour are approximately RMB 16.39 million per year.

[0038] Changing the number, specifications, and arrangement of burners, the number, specifications, and arrangement of air distribution plates, the internal packing structure, and the equipment support method can achieve the same function. The core concept of this invention is to integrate high-temperature oxidation release and thermal backup energy storage into a single device. Simultaneously, the high-temperature oxidation release integrates afterburning and mixed combustion, and the high-temperature oxidation energy release integrates a synthetic burner, thermal storage filling materials, flue gas mixing, and a fuel premixer. Any implementation based on the inventive concept of this invention falls within the protection scope of this invention.

[0039] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An adiabatic combustion device for low-calorific-value exhaust gas, characterized in that, The burner and the high-temperature flue gas mixer are connected sequentially from bottom to top (4); The burner is provided with a combustion chamber shell (2) on its outer periphery, and a high-temperature combustion chamber (3) is provided inside it. The burner is connected to the high-temperature combustion chamber (3), and a mixer (1) is provided at the bottom of the combustion chamber shell (2). The top of the combustion chamber shell (2) is connected to a high-temperature flue gas mixer (4).

2. The adiabatic combustion device for low-calorific-value emission gas according to claim 1, characterized in that, The mixer (1) is provided with a through pipe, and the fuel gas inlet (11) and the oxidant inlet (12) are respectively connected from the left and right sides of the pipe. The downstream pipes of the two inlets converge to the front flow channel of the premixed airflow guide (13). The outlet end of the premixed airflow guide (13) is directly connected to the radial fluid guide device (14).

3. The adiabatic combustion device for low-calorific-value exhaust gas according to claim 1 or 2, characterized in that, The combustion chamber shell (2) is configured such that the skirt (21) serves as the bottom support structure and is directly welded and fixed to the bottom flange of the combustion chamber shell; the support plate (22) is horizontally mounted on the lower middle inner wall of the combustion chamber shell to provide installation support for the upper air distribution plate and buffer box; the pressure relief port (23) extends outward from the upper middle part of the side wall of the combustion chamber shell and is the safe release interface of the cavity; the air jacket (24) is an annular cavity wrapped between the outer wall of the high-temperature combustion chamber and the inner wall of the combustion chamber shell, and the inlet and outlet of the jacket are respectively opened on the side wall of the shell; the temperature sensor (25) and thermocouple (26) are inserted into the cavity from different height positions on the side wall of the combustion chamber shell to complete multi-point temperature monitoring; the inspection port (27) is opened on the top slope of the combustion chamber shell and directly connects to the internal space of the high-temperature combustion chamber.

4. The adiabatic combustion device for low-calorific-value exhaust gas according to claim 1 or 2, characterized in that, The high-temperature combustion chamber (3) is configured such that the premixed medium buffer box (31) is fixed above the support plate (22), and its inlet end is directly connected to the outlet pipe of the mixer to receive the premixed combustible medium; the heat insulation energy storage layer (32) is completely attached to the inner wall surface of the high-temperature combustion chamber to form a complete heat insulation energy storage lining; the igniter (33) is inserted from the side opening of the combustion chamber shell and installed in the upper area of ​​the premixed medium buffer box, aligned with the combustion ignition position; the air distribution plate (34) is horizontally installed on the top of the premixed medium buffer box, and the ventilation net (341) is laid on the opening surface of the air distribution plate. After the two are combined, the medium in the buffer box is evenly distributed upward into the combustion area.

5. The adiabatic combustion device for low-calorific-value exhaust gas according to claim 1 or 2, characterized in that, The high-temperature flue gas mixer (4) is connected to the top outlet of the high-temperature combustion chamber; the low-temperature circulating air inlet (41) is opened at the top left interface of the high-temperature flue gas mixer, and the thermal inert gas outlet (42) is opened at the rightmost end face of the high-temperature flue gas mixer; the high-temperature flue gas inlet (43) is connected to the upper left cavity of the high-temperature flue gas mixer, and the distributor (44) is installed downstream of the high-temperature flue gas inlet to evenly disperse the incoming flue gas; the spray device (45) is arranged horizontally in the downstream cavity of the distributor, the swirl vane (46) is installed in the flow channel behind the spray section, and the dust removal device (47) is set at the tail end of the high-temperature flue gas mixer (4). After the final gas-solid separation is completed, the clean conditioning gas is sent out from the thermal inert gas outlet (42).

6. An adiabatic combustion process for low-calorific-value emissions, characterized in that, The process utilizes an adiabatic combustion apparatus for low-calorific-value exhaust gases as described in any one of claims 1-5, comprising: The low-calorific-value gas to be treated enters through the fuel gas inlet (11) and mixes with the air introduced through the oxidant inlet (12). It is then mixed and guided by the premixed airflow guide (13). The premixed gas is sent to the premixed medium buffer box (31) through the radial fluid guide device (14). It is then sent to the upper heat storage layer (32) through multiple longitudinally stacked air distribution plates (34) and air caps to store energy and heat it to 150°C above the actual combustion temperature of the fuel medium. The low-temperature circulating air enters the high-temperature flue gas mixer (4) through the low-temperature circulating air inlet (41). The medium-temperature thermal inert medium with a suitable temperature is sent to the downstream system through the thermal inert gas outlet (42).

7. The adiabatic combustion process for low-calorific-value emission gas according to claim 6, characterized in that, The specific process flow of the high-temperature flue gas mixer (4) includes: Low-temperature circulating air is introduced from the low-temperature circulating air inlet (41) at the top, and mixes with the high-temperature flue gas from the high-temperature flue gas inlet (43). Under the action of the distributor (44), the mixed high-temperature flue gas is cooled down. After cooling down, the mixed high-temperature flue gas is desulfurized and denitrified by the spray device (45), and then fully contacted by the swirl plate (46). After being treated by the dust removal device (47), it is discharged from the thermal inert gas outlet (42) at the tail end for use.

8. The adiabatic combustion process for low-calorific-value emission gas according to claim 6, characterized in that, Specifically, it includes: First, high-calorific-value gas is introduced into the high-temperature combustion chamber (3) as fuel, and ignition is carried out by igniter (33) to raise the temperature in the opposite direction to the normal airflow, heating the heat insulation storage layer (32) and the furnace body refractory material; during this period, the thermal inert gas outlet (42) is closed; After the temperature of the thermal insulation energy storage layer (32) is 150°C higher than the fuel reaction temperature and the temperature of the low temperature preheating zone is 300°C lower than the combustion temperature, the supply of high calorific value gas is stopped. After the low-calorific-value gas and preheated air are fully premixed in the mixer (1), they flow through the air distribution plate (34) and enter the high-temperature combustion chamber (3). The temperature of the combustion device is monitored in real time by thermocouples (26) and temperature sensors (25) installed on the combustion chamber shell (2). After the system is running stably, the thermal inert gas outlet (42) is opened. The high-temperature flue gas flows to the high-temperature flue gas mixer (4) at the top. The purified thermal inert gas after cooling, denitrification, desulfurization and denitrification and dust removal is used.

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