Tar incineration device and biomass raw material gasification system

Abstract

The invention discloses a tar incineration device and a biomass raw material gasification system, the tar incineration device comprises a tar pool, a condensate water evaporator, a tar direct combustion furnace and an air heat exchanger, tar passes through the tar pool and the condensate water evaporator and enters the tar direct combustion furnace to be incinerated; the tar direct combustion furnace generates flue gas, and the flue gas passes through the air heat exchanger and the condensate water evaporator to realize gradient utilization of heat; the biomass raw material gasification system comprises the tar incineration device and a gasification furnace, and the tar direct combustion furnace is provided with a dual-fuel combustor. Innocent treatment and heat energy recovery of tar are realized through a closed-loop process of tar pool mixing viscosity reduction, condensate water evaporator quality improvement and tar direct combustion furnace high-temperature incineration; the dual-fuel combustor supports flexible switching of multiple fuels and can meet different requirements of multiple working conditions; according to the system, a closed-loop energy chain of biomass raw materials, synthesis gas and tar and heat energy recovery is constructed, biomass energy is recovered to the maximum extent, and dependence on external fuel is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of tar processing, and in particular to a tar incineration device and a biomass raw material gasification system. Background Art

[0002] Biomass gasification technology, as a highly efficient renewable energy conversion method, converts biomass feedstocks (such as straw and wood chips) into syngas (primarily composed of CO, H₂, and CH₄) through a thermochemical process. It is widely used in power generation, heat supply, and chemical feedstock production. However, during the gasification process, incomplete pyrolysis of biomass feedstock under oxygen-deficient or oxygen-limited conditions produces tar (a viscous byproduct composed of complex hydrocarbons such as benzene, phenols, and polycyclic aromatic hydrocarbons). The presence of tar not only degrades the syngas quality and causes coking and corrosion in downstream equipment (such as gas turbines and catalysts), but its direct emissions also cause severe environmental pollution, threatening the ecological environment and human health.

[0003] The existing tar treatment technology has the following defects: 1. A single gasifier is equipped with an independent incineration or catalytic device, resulting in a surge in equipment investment and operation and maintenance costs, and poor economic efficiency for small and medium-sized systems; 2. During centralized treatment, tar, due to its high viscosity (>1000 cP), easily solidifies and clogs the pipeline, requiring frequent maintenance. The accumulation of volatile organic compounds (VOCs) can also pose a safety hazard. 3. Traditional incineration consumes large amounts of diesel and natural gas for combustion support. Low-temperature combustion also produces pollutants such as CO and polycyclic aromatic hydrocarbons (PAHs). This leads to low waste heat utilization and significant energy waste. Existing improvement options (such as heat tracing and insulation, and dilution and viscosity reduction) are limited by energy consumption, cost, or separation difficulties, making them difficult to scale up.

[0004] Therefore, there is an urgent need for a tar treatment technology that takes into account low cost, anti-clogging and efficient and clean incineration. Summary of the Invention

[0005] The purpose of this application is to overcome the deficiencies in the prior art and to provide a tar incineration device and a biomass raw material gasification system.

[0006] The present application provides a tar incineration device, which is characterized in that it includes: a tar pool for storing tar, in which the tar can be mixed with condensed water to form a first mixture that is convenient for circulation in the pipeline; a condensed water evaporator, connected to the tar pool, after the first mixture enters the condensed water evaporator, the condensed water therein is evaporated into water vapor, and the water vapor is mixed with the tar to form a second mixture; a tar direct-fired furnace, connected to the condensed water evaporator, after the second mixture enters the tar direct-fired furnace, it is incinerated to generate hot flue gas; an air heat exchanger, connected to the tar direct-fired furnace, the hot flue gas enters the air heat exchanger and serves as a heat source for the air heat exchanger, the hot flue gas can preheat the air, and the obtained hot air can be used as a gasification agent for the gasification furnace; the flue gas after passing through the air heat exchanger and completing one heat exchange flows to the condensed water evaporator, and serves as a heat source for the condensed water evaporator.

[0007] Furthermore, the tar pool is equipped with: a temperature control mechanism for regulating the temperature of the first mixture in the tar pool so that the first mixture is maintained at 60-80°C; and / or a density sensor for monitoring the density of the first mixture, thereby inferring the ratio of tar to water therein; and / or a viscometer for monitoring the viscosity of the first mixture to ensure that it meets the transportation requirements; and / or an agitator for stirring the first mixture to prevent the tar from settling and clumping.

[0008] Furthermore, the tar incineration device also includes a first condenser, which is arranged on the heat source discharge pipeline of the condensate evaporator and is used to condense water vapor in the flue gas passing through the condensate evaporator to obtain condensed water, and the condensed water can flow back into the tar pool.

[0009] Furthermore, the tar incineration device also includes a second condenser, which is arranged on the heat exchange discharge pipeline of the condensate evaporator and is used to condense the water vapor in the second mixture discharged through the condensate evaporator to obtain condensed water, and the condensed water can flow back into the tar pool; through the diversion of the second condenser, the proportion of water vapor in the second mixture can also be reduced, thereby avoiding water vapor interfering with the incineration of tar.

[0010] Furthermore, in the tar pool, the ratio of tar to water is 1:1-1:3; after the water vapor is diverted through the second condenser, the ratio of tar to water vapor in the second mixture entering the tar direct-fired furnace is 2:1-3:1.

[0011] Furthermore, the tar incineration device also includes a water replenishing mechanism, which is used to increase the proportion of water in the first mixture; the water replenishing mechanism includes: a water preparation tank, which is used to supply softened ordinary water; and a heater, which is used to preheat the ordinary water so that the temperature of the ordinary water is close to the temperature of the tar in the tar pool.

[0012] Furthermore, a heating layer is provided outside the tar pool and / or the pipe connecting the tar pool to the condensate evaporator; the heating layer is connected to the heat source discharge pipeline of the condensate evaporator; the flue gas discharged from the condensate evaporator enters the heating layer, which can maintain the temperature of the first mixture.

[0013] The present application also provides a biomass raw material gasification system, including the above-mentioned tar incineration device, and also includes a gasifier, which can convert the biomass raw material into synthesis gas through high-temperature thermochemical reactions, accompanied by tar and water vapor; the tar direct-fired furnace is equipped with a dual-fuel burner, which can not only burn natural gas or diesel, but also burn the synthesis gas produced by the gasifier and the second mixture.

[0014] Furthermore, the biomass raw material gasification system also includes a third condenser, which is arranged on the exhaust pipe of the gasifier and is used to cool the gasification products discharged from the gasifier so that the tar and water vapor in the gasification products are condensed into liquid; the condensed tar and condensed water enter the tar pool.

[0015] Furthermore, the condensation temperature of the third condenser is 80-150°C to separate the synthesis gas in the gasification product and condense the tar and water vapor into liquid; the temperature of the first mixture in the tar pool is maintained at 60-80°C to prevent the tar from solidifying and ensure the fluidity of the first mixture; the operating temperature of the condensate evaporator is 100-120°C to facilitate complete evaporation of water in the first mixture and gasify some light components in the tar while the heavy components remain in liquid form; the combustion temperature of the tar direct-fired furnace is 1000-1200°C; the temperature of the hot flue gas discharged from the tar direct-fired furnace is 600-800°C, the hot flue gas enters the air heat exchanger, and is cooled to 400-500°C after one heat exchange, the air is preheated to 300-450°C, and the cooled flue gas enters the condensate evaporator and is cooled to 80-150°C after two heat exchange.

[0016] The present application provides a tar incineration device, including a tar pool, a condensed water evaporator, a tar direct-fired furnace and an air heat exchanger. The tar passes through the tar pool and the condensed water evaporator in sequence and finally enters the tar direct-fired furnace to be incinerated; the tar direct-fired furnace generates flue gas, and the flue gas passes through the air heat exchanger and the condensed water evaporator in sequence, realizing the cascade utilization of energy through heat exchange. The tar incineration device provided by the present application avoids pipe blockage and pumping difficulties caused by the high viscosity of tar by mixing tar with condensed water to form a first mixture with better fluidity, thereby ensuring the stability of system operation; the condensed water evaporator is used to evaporate the water in the first mixture to form a second mixture that is easy to atomize, and combined with the high-temperature incineration process of the tar direct-fired furnace, the combustion efficiency is improved, the emission of pollutants such as black smoke and polycyclic aromatic hydrocarbons is reduced, and clean incineration is achieved; at the same time, the hot flue gas is used to perform two heat exchanges with the air and the first mixture in sequence, and the waste heat is utilized in a cascade manner, which reduces the consumption of external energy and improves the energy efficiency of the system. In addition, the tar incineration device provided in this application can be used in conjunction with a gasification furnace, a carbonization furnace, etc., which can realize centralized processing of tar, reduce equipment investment and maintenance costs, and enhance compatibility with multiple equipment scenarios.

[0017] The present application also provides a biomass raw material gasification system, including the above-mentioned tar incineration device, and also includes a gasifier, and the tar direct-fired furnace is equipped with a dual-fuel burner; by integrating the tar incineration device and the dual-fuel burner, the problems of difficult tar treatment, poor fuel adaptability and high dependence on external energy in traditional biomass gasification are effectively solved; the system realizes harmless treatment and heat recovery of tar through a closed-loop process of tar pool mixing and viscosity reduction, condensed water evaporator quality improvement and high-temperature incineration in the tar direct-fired furnace, avoiding tar clogging pipelines and polluting the environment; the dual-fuel burner supports natural gas, diesel, and synthetic The system can flexibly switch between multiple fuels such as biomass and tar to meet the different needs of multiple operating conditions such as startup, low load, and normal operation. At the same time, the dual-fuel burner uses the high reactivity of synthesis gas to promote tar cracking and improve combustion efficiency through the coordinated combustion of multiple fuels. It can also further clean the residual impurities in the synthesis gas when burning it. The system has constructed a closed-loop energy chain of "biomass raw materials → synthesis gas + tar → heat energy recovery", maximizing the recovery of biomass energy, reducing dependence on external fuels, and reducing overall energy consumption through the cascade utilization of waste heat, thus realizing a stable, environmentally friendly and economical biomass gasification process. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic structural diagram of a biomass raw material gasification system provided in this application; Figure 2 A schematic diagram of a process for processing gasification products provided in this application; Figure 3 A schematic diagram of the cascade utilization of flue gas waste heat provided in this application. DETAILED DESCRIPTION

[0019] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0020] The present application provides a tar incineration device, including: a tar pool 1 for storing tar, where the tar can be mixed with condensed water in the tar pool 1 to form a first mixture that is convenient for circulation in the pipeline; a condensed water evaporator 2, connected to the tar pool 1, where the first mixture enters the condensed water evaporator 2, where the condensed water therein is evaporated into water vapor, and the water vapor and the tar form a second mixture; a tar direct-fired furnace 3, connected to the condensed water evaporator 2, where the second mixture enters the tar direct-fired furnace 3 and is incinerated to generate hot flue gas; an air heat exchanger 4, connected to the tar direct-fired furnace 3, where the hot flue gas enters the air heat exchanger 4 and serves as a heat source for the air heat exchanger 4. The hot flue gas can preheat the air, and the obtained hot air can be used as a gasifying agent for the gasification furnace; the flue gas after passing through the air heat exchanger 4 and completing one heat exchange flows to the condensed water evaporator 2, where it serves as a heat source for the condensed water evaporator 2.

[0021] Specifically, tar tank 1 is used to hold tar and water. The water is primarily condensed water, which is formed when water vapor contained in high-temperature gas condenses below its dew point during the cooling process. In this application, the high-temperature gas is generated by the gasification system, specifically flue gas and syngas. Therefore, the condensed water in this application is a product of the gasification system and can be recycled. In actual use, if the amount of condensed water is insufficient, other liquids that are easily mixed with tar and can improve its fluidity (such as deionized water or softened water) can also be used.

[0022] The tar incineration device provided in this application can be used in conjunction with equipment that produces tar, such as a gasifier and a carbonizer, or it can be set up independently and specifically used to process tar.

[0023] Figure 1 In the embodiment shown, the tar incineration device is used in conjunction with at least one set of gasifiers. After the gasifiers process the biomass raw materials, tar is produced, which is fed into the tar pool 1 and mixed with water to form a first mixture.

[0024] It's important to explain that tar has a relatively high viscosity at room temperature (for example, coal tar can reach over 1000 mPa·s), resulting in extremely poor fluidity. Direct pumping can easily clog pipes. Mixing tar with water acts as a diluent, reducing the tar's viscosity (for example, a 1:1 mixture of tar and water can reduce viscosity by over 50%). Furthermore, the presence of water allows the mixture to form an "oil-in-water" dispersion within the pipe, reducing direct adhesion of the tar to the pipe wall. Furthermore, the addition of water lowers the tar's flash point (from 580°C to 480°C), shortening preheating time before incineration and saving energy.

[0025] In the tar tank 1 , condensed water is preferably mixed with tar.

[0026] This is because condensed water, derived from the cooling and condensation of water vapor within the syngas or flue gas within the system (described in detail below), is naturally compatible with tar. Since condensed water often dissolves trace amounts of tar components (such as light aromatics like benzene and toluene) during its formation, it more easily forms a uniform and stable solution when mixed with tar through intermolecular forces, rather than a traditional oil-water emulsion. This reduces the risk of stratification. This homogeneous nature also helps maintain the long-term stability of the first mixture within the tar tank 1 and pipelines, preventing pump blockages and uneven evaporation caused by stratification.

[0027] Secondly, the temperature characteristics of the condensed water are highly compatible with the tar. The condensed water temperature within the system is typically 80-150°C (e.g., the condensed water discharged from the third condenser 7 is approximately 80°C, and the condensed water returning from the second condenser 6 is approximately 100°C). This is close to the 60-80°C temperature range maintained in the tar tank 1. This prevents the localized sudden cooling and solidification of tar caused by the large temperature difference associated with traditional makeup water (e.g., 20°C tap water), ensuring smooth and stable mixing and transportation.

[0028] Furthermore, condensate, as a system byproduct, can be used directly to dilute tar without additional treatment. This prevents the introduction of minerals from external water sources, such as calcium and magnesium ions, which typically have a hardness greater than 100 ppm. These ions react with phenolic acids in tar to form insoluble precipitates such as calcium phenate, which can easily clog pipelines and valves over time. Condensate hardness is less than 5 ppm, eliminating the risk of scaling at the source.

[0029] The preferred mixture of condensed water and tar not only takes advantage of the natural adaptability of resources within the system, but also solves the defects of traditional water replenishment methods through temperature matching and water quality optimization.

[0030] In the gasification system provided in the present application, there are three main sources of condensed water. First, the gasification product generated by the gasification furnace is cooled by the third condenser 7, and the water vapor therein condenses into liquid water because the temperature drops below the dew point; second, the high-temperature flue gas generated by the tar direct-fired furnace 3 passes through the first condenser 5, and the water vapor therein is cooled and condensed and precipitated; third, the excess water vapor that passes through the condensed water evaporator 2 and does not enter the tar direct-fired furnace 3 to participate in the incineration is cooled and condensed by the second condenser 6 (see below for details).

[0031] The condensed water flows into the tar pool 1 and mixes with the tar to form a first mixture, thereby realizing the recycling of water resources in the system.

[0032] Continue to refer to Figure 1 The condensate evaporator 2 is connected to the tar tank 1 via a pipeline. A centrifugal pump is installed on the pipeline. The centrifugal pump is driven by mechanical energy to transport the first mixture in the tar tank 1 to the condensate evaporator 2. The condensate evaporator 2 heats the first mixture through heat exchange to a temperature above 100°C. The water in the first mixture is evaporated into water vapor, and the tar and water vapor form a second mixture.

[0033] It's important to explain that the reason the first mixture isn't directly incinerated is because untreated tar has a high viscosity and complex composition (including heavy components like polycyclic aromatic hydrocarbons). Direct combustion results in poor atomization and can easily lead to incomplete combustion due to uneven mixing, producing black smoke and pollutants like polycyclic aromatic hydrocarbons. After the water is evaporated in condensate evaporator 2, the tar viscosity decreases further. The resulting second mixture, formed by mixing with water vapor, has a smaller particle size, making it more accessible to oxygen (increasing its specific surface area), thereby improving combustion efficiency.

[0034] Secondly, the evaporation process can separate some light acidic components (such as phenol) in the tar, and at the same time consume the carbon element in the tar through the water-gas reaction (C+H2O→CO+H2), reducing carbon deposits and extending equipment life.

[0035] In addition, water vapor can act as a gasifying agent to participate in high-temperature reactions, cracking heavy components in tar (such as asphaltene) into small molecular combustible gases such as CO and H2, increasing the calorific value of combustion. At the same time, through the dilution effect of water vapor, the combustion temperature is controlled at around 1000℃, suppressing NO X Generation.

[0036] Furthermore, the evaporation of liquid water requires a latent heat of vaporization of 2260 kJ / kg. If the water-containing tar were burned directly, this heat would need to be provided by the tar direct-fired furnace 3. After the condensed water evaporator 2 utilizes the flue gas's waste heat to evaporate the water, the water vapor participates in the combustion in gaseous form, avoiding the additional energy consumption of the tar direct-fired furnace 3. Furthermore, the gaseous water vapor mixes more easily with the tar, reducing combustion temperature fluctuations and preventing sudden drops in furnace temperature caused by the sudden evaporation of liquid water (for example, evaporating 1 kg of water can reduce the temperature of 1000°C flue gas by approximately 200°C), thus ensuring combustion stability.

[0037] In one embodiment, the condensate evaporator 2 adopts a shell-and-tube heat exchanger structure, including a tube side, a shell side, and auxiliary components; the tube side is used for the circulation of the first mixture and adopts a multi-tube pass design (e.g., 2-4 passes). The pipe material is 316L stainless steel (tar corrosion resistant), the pipe diameter is Φ25×2.5mm, and the flow rate in the pipe is 0.5-1m / s to ensure that the first mixture is evenly heated; the shell side is used for the circulation of flue gas. The shell side cover is arranged outside the tube side, and the flue gas in the shell side can flow along the outside of the tube bundle. The shell is made of Q345R carbon steel and is equipped with baffles (spacing 300-500mm). The baffles can guide the flue gas to flush the tube bundle horizontally, enhance the turbulence effect, and improve the heat transfer coefficient.

[0038] During operation, the flue gas transfers heat to the first mixture in the tube through the tube wall, causing the moisture therein to evaporate into water vapor.

[0039] Continue to refer to Figure 1 The tube outlet of the condensed water evaporator 2 is connected to the tar direct-fired furnace 3 via a heat exchanger discharge pipeline. The second mixture can be transported along the heat exchanger discharge pipeline to the tar direct-fired furnace 3. The tar direct-fired furnace 3 is equipped with a dual-fuel burner 3a and an oxygen-supplementing blower. The second mixture can mix with oxygen in the tar direct-fired furnace 3 and be completely burned at a high temperature of approximately 1000°C.

[0040] In one specific embodiment, the tar direct-fired furnace 3 includes an insulated furnace chamber. This chamber consists of a refractory inner layer (made of corundum bricks, resistant to 1790°C, and 230mm thick), an insulation layer (made of lightweight high-alumina bricks, 114mm thick), and a steel outer shell, effectively reducing heat loss (outer wall temperature <60°C). The furnace chamber is cylindrical, with an inner diameter of 1.2-2m and a height of 3-5m. A slag discharge port is located at the bottom.

[0041] During operation, the second mixture enters the insulated furnace, where cracking and combustion reactions occur at temperatures around 1000°C. The high-temperature flue gas generated by combustion remains in the furnace for >2 seconds, ensuring the complete decomposition of harmful substances such as dioxins. The resulting ash (containing minerals such as potassium and sodium) is deposited at the bottom of the furnace and is regularly discharged.

[0042] Continue to refer to Figure 1The flue gas outlet of the tar direct-fired furnace 3 is connected to an air heat exchanger 4 via a pipe. This air heat exchanger 4 is equipped with a blower. After the hot flue gas from combustion enters the air heat exchanger 4, it exchanges heat with cold air, preheating the air to its initial temperature, allowing it to enter the gasifier as a gasifying agent.

[0043] In one specific embodiment, the air heat exchanger 4 utilizes a plate-fin heat exchanger. It is composed of a fin bundle of aluminum alloy or stainless steel (aluminum alloy is suitable for flue gas temperatures below 500°C, while stainless steel is suitable for flue gas temperatures between 600°C and 800°C). Partitions are installed within the fin bundle to form flue gas and air channels. The fins are 0.2-0.5 mm thick and spaced 2-5 mm apart. In a plate-fin heat exchanger, the shell side corresponds to a flow path with a larger cross-sectional area and wider fin spacing, while the tube side corresponds to a flow path with a smaller cross-sectional area and closer fin spacing.

[0044] During operation, flue gas flows through the shell side, while cold air flows through the tube side, with the two in countercurrent or crosscurrent distribution. The hot flue gas (600-800°C) transfers heat to the cold air (normal temperature 20°C) through the fins and baffles, preheating the air to 300-450°C. Ultimately, the hot air flows through the tube side outlet of air heat exchanger 4 to the gasifier. The cooled flue gas, after undergoing heat exchange, flows through the shell side outlet of air heat exchanger 4 to the shell side inlet of condenser evaporator 2. The hot air serves as the gasifier's gasifying agent, while the flue gas serves as the heat source for condenser evaporator 2.

[0045] In summary, tar passes through tar pool 1 and condensate evaporator 2 in sequence, and finally enters tar direct-fired furnace 3 for incineration. Tar direct-fired furnace 3 generates flue gas, which passes through air heat exchanger 4 and condensate evaporator 2 in sequence, achieving cascade energy utilization through heat exchange.

[0046] It's important to note that in biomass feedstock gasification systems, separation is used instead of direct combustion of gasification products because syngas, as a high-value product (containing combustible components such as CO and H2), is often prioritized for use in power generation and heating applications. In these scenarios, direct combustion of the gasification products would contaminate the syngas with impurities such as ash and tar, reducing its calorific value and increasing pipeline resistance, thereby impacting the stability and service life of subsequent equipment. By separating the syngas from the gasification products and reducing its tar content to less than 1g / m³, the syngas can be used independently as a clean fuel.

[0047] Secondly, for multiple tar-producing equipment such as gasifiers and carbonizers, the tar is collected and put into the tar pool 1 for unified treatment, which can avoid problems such as excessive system complexity and high cost caused by decentralized treatment.

[0048] Furthermore, tar is a highly viscous liquid or semi-solid at room temperature. If transported mixed with syngas, it can easily solidify and deposit in pipes and valves, causing blockages. Separating the syngas from the tar reduces transport resistance. After tar is upgraded in the condensate evaporator (temperature 100-120°C, viscosity reduced to 300-400 cP), its fluidity is significantly improved, making it more suitable for centralized incineration.

[0049] Furthermore, when syngas needs to be burned and cleaned for gasification product discharge, the presence of tar in the syngas can reduce the calorific value of the gas and affect combustion stability. Tar combustion also consumes additional energy (e.g., evaporating 1 kg of water requires 600 kJ) and can easily produce pollutants such as black smoke and polycyclic aromatic hydrocarbons due to incomplete combustion. After separation, the syngas can be stably burned as a clean fuel in the dual-fuel burner 3a, while the tar is incinerated at high temperature in the tar direct-fired furnace 3, achieving the dual goals of efficient pollutant degradation and energy recovery.

[0050] The tar incineration device provided by the present application avoids pipe blockage and pumping difficulties caused by the high viscosity of tar by mixing tar with condensed water to form a first mixture with better fluidity, thereby ensuring the stability of the system operation; the condensed water evaporator 2 is used to evaporate the water in the first mixture to form a second mixture that is easy to atomize, and combined with the high-temperature incineration process of the tar direct-fired furnace 3, the combustion efficiency is improved, the emission of pollutants such as black smoke and polycyclic aromatic hydrocarbons is reduced, and clean incineration is achieved; at the same time, the hot flue gas is used to perform heat exchange with the air and the first mixture twice in sequence, and the waste heat is used in a cascade manner, which reduces the consumption of external energy and improves the energy efficiency of the system. In addition, the tar incineration device provided by the present application can be used in conjunction with a gasification furnace, a carbonization furnace, etc., which can realize the centralized treatment of tar, reduce equipment investment and maintenance costs, and enhance compatibility with multiple equipment scenarios.

[0051] Optionally, the tar pool 1 is provided with a temperature control mechanism, which is used to regulate the temperature of the first mixture in the tar pool 1 so as to maintain the first mixture at 60-80°C.

[0052] At low temperatures (e.g., <50°C), tar viscosity increases and solidifies, potentially blocking pipelines or pumping equipment. High temperatures (>100°C) can volatilize light components in tar, such as benzene and toluene, increasing environmental and safety risks. Furthermore, temperature fluctuations can cause tar to separate from condensed water, compromising subsequent processing.

[0053] Maintaining the first mixture at 60-80°C is beneficial to maintaining its low viscosity (<500cP), maintaining its fluidity, and avoiding volatilization and stratification problems. In one embodiment, the temperature control mechanism utilizes electric heating. Specifically, an electric heating cable, such as a self-limiting temperature heating cable or a mineral-insulated heating cable, is installed on the outer wall of the tar pit 1 and on the outside of the pipe connecting the tar pit 1 to the condensed water evaporator 2. A thermostat is used to set a target temperature (e.g., 70°C). The heating cable automatically adjusts its heating value based on temperature fluctuations, achieving precise temperature control within ±0.5°C.

[0054] In another embodiment, the temperature control mechanism uses steam tracing. Specifically, a spiral steam coil is arranged on the outer wall of the tar pool 1, and high-temperature steam (which can be supplied by an independent external device or replaced by flue gas at a suitable temperature) is introduced to indirectly heat the tar pool 1.

[0055] In another embodiment, the outer wall of the tar pit 1 is wrapped with insulating materials such as rock wool and polyurethane to form an insulation layer. The insulation layer has a thickness of 80-150 mm and a thermal conductivity of less than 0.04 W / (m·K). It is also covered with a reflective aluminum foil layer and a protective layer of color-coated steel plate. This insulation layer reduces heat exchange between the pit and the surrounding environment, minimizing heat loss. This insulation layer is often combined with electric or steam heating to further maintain temperature stability.

[0056] Optionally, the tar pool 1 is equipped with a density sensor, which is used to monitor the density of the first mixture, thereby inferring the ratio of tar to water therein.

[0057] For example, the density sensor uses a vibrating density meter (such as a Coriolis mass flowmeter) to calculate the density by detecting the vibration frequency of the mixture.

[0058] Specifically, assuming that the volume fraction of tar is x, the density ρ = 1.2x + 1.0(1 − x), and x can be calculated by measuring the density.

[0059] During operation, when the density sensor detects a ratio deviation (such as tar: water>1:1), the control system can increase the condensate return flow or activate the water replenishment mechanism to add water to the tar pool 1 until the density returns to the set range.

[0060] Optionally, the tar tank 1 is equipped with a viscometer, which is used to monitor the viscosity of the first mixture to ensure that it meets the transportation requirements; For example, the viscometer uses a rotational viscometer, a paddle rotor is immersed in the first mixture, and the torque is measured at a rotation speed of 20 rpm and converted into a viscosity value.

[0061] During operation, when the viscometer detects that the viscosity is greater than the preset value (such as >500cP), the control system can correspondingly adjust the temperature, or add water, or remind workers to intervene, thereby ensuring that the first mixture in the system can flow smoothly.

[0062] Optionally, the tar pool 1 is equipped with a stirrer for stirring the first mixture to prevent the tar from settling and agglomerating.

[0063] For example, the agitator adopts an anchor-type or frame-type stirring blade (with a diameter of 0.6-0.8 times the pool diameter) and a rotation speed of 5-10 rpm to generate radial and axial mixed flows.

[0064] During operation, the agitator blades are kept close to the tank bottom, stirring at a low speed to prevent tar particles from settling. This agitation also improves the mixing efficiency of the tar and water. If a viscometer is installed and detects that the viscosity of the first mixture exceeds a preset value, stirring can also be used to improve the fluidity of the first mixture.

[0065] Optionally, the tar incineration device provided in the present application also includes a first condenser 5, which is arranged on the heat source discharge pipeline of the condensed water evaporator 2, and is used to condense water vapor in the flue gas passing through the condensed water evaporator 2 to obtain condensed water, and the condensed water can flow back into the tar pool 1.

[0066] For details, please refer to Figure 1 In the illustrated embodiment, a heat source discharge pipeline is provided at the shell-side outlet of the condensate evaporator 2, and a first condenser 5 is installed on the heat source discharge pipeline. The hot flue gas discharged from the tar direct-fired furnace 3 passes through the air heat exchanger 4 and the condensate evaporator 2, and then enters the first condenser 5 along the heat source discharge pipeline. The water vapor contained in the flue gas is condensed into liquid water, and the condensed water is returned to the tar tank 1.

[0067] In one embodiment, the first condenser 5 utilizes a shell-and-tube condenser equipped with spiral baffles. The shell side carries the flue gas, while the tube side carries the cooling medium (e.g., cooling water or air). After two heat exchanges, the flue gas enters the first condenser 5 and undergoes heat exchange with the cooling medium (e.g., circulating water, at a temperature of 20-30°C) in the tube side. This reduces the flue gas temperature to 60-80°C. Because the flue gas temperature is below the dew point, the water vapor condenses into liquid water. This condensed water adheres to the tube bundle surface and collects in a sump at the bottom. It is ultimately discharged through a steam trap and recirculated along a pipeline back to the tar tank 1. In the tar tank 1, an agitator uniformly mixes the condensed water and tar, reducing the viscosity of the first mixture while maintaining fluidity. A density sensor monitors the density of the first mixture in real time, providing feedback to the water replenishment mechanism, which dynamically adjusts the water replenishment to ensure a stable tar-water ratio.

[0068] In other embodiments, the first condenser 5 may be a heat source dependent device such as a dryer, a waste heat boiler, etc., so that the waste heat of the flue gas can be further utilized.

[0069] Optionally, the tar incineration device provided in the present application also includes a second condenser 6, which is arranged on the heat exchange discharge pipeline of the condensate evaporator 2, and is used to condense the water vapor in the second mixture discharged through the condensate evaporator 2 to obtain condensed water, and the condensed water can flow back into the tar pool 1; through the diversion of the second condenser 6, the proportion of water vapor in the second mixture can also be reduced, thereby avoiding water vapor interfering with the incineration of tar.

[0070] For details, please refer to Figure 1 In the illustrated embodiment, the outlet of the condensate evaporator 2 is equipped with a heat exchanger discharge pipeline connected to the tar direct-fired furnace 3. The heat exchanger discharge pipeline forks into two branches. The first branch connects to the tar direct-fired furnace 3, while the second branch houses a second condenser 6 and connects to the tar tank 1. After the first mixture passes through the condensate evaporator 2, the condensate is evaporated into water vapor, while the tar remains in liquid form. The gas-liquid two-phase flow consisting of gaseous water vapor and liquid tar has a significant density difference (water vapor density ≈ 0.6 kg / m³, tar droplet density ≈ 1000 kg / m³). Therefore, a certain degree of stratification will naturally occur in the heat exchanger discharge pipeline. Water vapor, due to its low density, accumulates in the upper part, while tar droplets, due to their high density, settle to the lower part. Taking advantage of this characteristic, the end of the heat exchanger discharge pipeline is designed to have two branches, one forking upward and the other. The upper branch is the second branch, which is used to supply gaseous water vapor. After the water vapor flows through the second condenser 6, it is condensed into liquid water and returned to the tar pool 1 for recycling. The lower branch is the first branch, which is used to transport liquid tar and entrained water vapor into the tar direct-fired furnace (3) for incineration.

[0071] The configuration and usage of the second condenser 6 are similar to those of the first condenser 5 and will not be described in detail.

[0072] Optionally, a humidity sensor is provided on the first branch, which is used to monitor the volume ratio of water vapor in the second mixture; an electric opening valve is provided on the second branch, which can automatically adjust the valve opening according to the signal feedback from the humidity sensor: when the water vapor content in the second mixture is greater than a preset value, the opening of the electric opening valve is increased to allow more water vapor to be condensed and recovered; when the water vapor content in the second mixture is less than the preset value, the opening of the electric opening valve is reduced to retain an appropriate amount of water vapor.

[0073] By controlling the amount of water vapor condensed, the ratio of tar to water vapor in the second mixture entering the tar direct-fired furnace 3 is maintained at a preset value, which can avoid excessive dilution of combustion efficiency by water and retain an appropriate amount of water vapor to participate in the water-gas reaction and promote complete combustion.

[0074] Optionally, a high-pressure atomizing nozzle is provided on the first branch line, and the tar and water vapor flow through the high-pressure atomizing nozzle before entering the tar direct-fired furnace 3 and are broken into micron-sized droplets. In this way, the specific surface area of the tar can be increased, making it easier for it to contact oxygen and improving combustion efficiency. At the same time, a high-speed turbulent boundary layer is formed on the surface of the droplets, which can promote the diffusion of water vapor molecules into the droplets. The surface tension of the tiny droplets produced by atomization is reduced, reducing the tendency of the droplets to coalesce, making it easier for the water vapor to wrap around the droplets to form a stable gas-liquid dispersion system. Therefore, the tar and water vapor mix more evenly. The uniform mixing causes the water vapor to form a "gasification agent shell" on the surface of the tar droplets, and the water-gas reaction occurs preferentially on the surface of the droplets, which can further improve the combustion efficiency. The H2 and CO produced by gasification, as intermediate products, can also reduce the cracking activation energy of the tar, making the heavy components in the tar easier to decompose, thereby promoting complete combustion.

[0075] Optionally, the tar direct-fired furnace 3 is equipped with a swirl burner, which can enhance the turbulence of the airflow and promote the full mixing of the second mixture and oxygen.

[0076] In one embodiment, a high-pressure atomizing nozzle is used in conjunction with a swirl burner. The tangential velocity component generated by the swirl burner creates a centrifugal force field between the gas and liquid phases, promoting thorough mixing of the secondary mixture with oxygen, extending the residence time of the secondary mixture within the furnace, and promoting secondary mixing in incompletely mixed areas. Furthermore, within the furnace, under the high temperature, water vapor within the liquid droplets expands, triggering micro-explosions that break the tar into smaller particles, further improving combustion efficiency.

[0077] Optionally, in the tar pool 1 , the ratio of tar to water is 1:1-1:3; after the water vapor is diverted through the second condenser 6 , the ratio of tar to water vapor in the second mixture entering the tar direct-fired furnace 3 is 2:1-3:1.

[0078] It should be noted that tar is a highly viscous liquid or semi-solid at room temperature. If left untreated, its high viscosity can lead to high flow resistance within pipelines, easily clogging them and seriously impacting the normal operation of the system. By mixing tar with water in a ratio of 1:1-1:3 in the tar pool 1, the dilution effect of water can be used to reduce the tar's viscosity, thereby improving its fluidity and facilitating pumping and pipeline transportation.

[0079] Experiments show that when the water content is greater than 50%, the fluidity of tar is significantly improved, but at the same time, it is necessary to avoid excessively high water content, which may lead to a surge in energy consumption for subsequent evaporation and incineration.

[0080] Generally speaking, high-viscosity tar (such as coal tar) requires a higher water content (1:2-1:3), while low-viscosity tar (such as biomass tar) can be reduced to a 1:1 ratio. In industrial incineration systems, tar and condensate are often mixed in a 1:2 ratio (66% water content) to balance fluidity and evaporation efficiency. In practical applications, online monitoring (such as viscometers and flow meters) can be combined to optimize the ratio in real time to ensure system efficiency and stability.

[0081] It should also be noted that if the water vapor content of the second mixture entering the tar direct-fired furnace 3 is too high, it can lead to adverse effects such as incomplete combustion, the production of black smoke, polycyclic aromatic hydrocarbons, and other harmful substances. It can also cause flame instability, potentially causing flameout or fluctuation. In addition, excessive water vapor absorbs a large amount of heat, lowering the furnace temperature, resulting in incomplete tar combustion and the generation of CO and unburned carbon particles.

[0082] By providing a second condenser 6 to divert water vapor, the ratio of tar to water vapor in the second mixture entering the tar direct-fired furnace 3 is controlled to 2:1-3:1. The appropriate amount of water vapor promotes the water-gas reaction, cracking the heavy tar components into combustible gases, thereby improving combustion efficiency. At the same time, the negative effects of excessive water vapor (e.g., a tar:water vapor ratio of less than 1:1) are avoided, maintaining the temperature within the direct-fired furnace at a high level (1000-1200°C), effectively improving combustion efficiency and reducing pollutant emissions.

[0083] In one embodiment, the tar tank 1 is equipped with a density sensor. By monitoring the density of the first mixture, the ratio of tar to condensed water can be inferred. The tar tank 1 is also equipped with a viscometer to detect whether the viscosity of the first mixture meets the delivery standard. The heat exchange discharge pipeline of the condensed water evaporator 2 is bifurcated into two branches. The first branch connects to the tar direct-fired furnace 3, and the second branch is equipped with a second condenser 6 and connected to the tar tank 1. The first branch is equipped with a humidity sensor, and the second branch is equipped with an electric opening valve. The humidity sensor and the electric opening valve work together to control the ratio of tar to water vapor in the second mixture entering the tar direct-fired furnace 3.

[0084] Specifically, if the density of the first mixture deviates from the set range, it indicates a change in the tar-to-condensed water ratio. Simultaneously, the viscosity of the first mixture is confirmed using a viscometer. Since tar viscosity decreases significantly with increasing water content, viscosity data can help determine whether the ratio is appropriate. If the viscosity does not meet delivery standards or the ratio deviates, the return flow of condensed water can be increased or supplemented with regular water. During the water replenishment process, real-time feedback from the density sensor and viscometer allows for precise control of the water replenishment volume to ensure the fluidity of the mixture and subsequent processing results.

[0085] At the same time, a humidity sensor monitors the water vapor content in the second mixture in real time. If the water vapor content is detected to be too high, causing the tar:water vapor ratio of the second mixture entering the tar direct-fired furnace 3 to deviate from the set range (e.g., tar:water vapor < 2:1), the electric opening valve is opened to increase the opening, allowing more water vapor to cool and reflux.

[0086] The density sensor, viscometer, humidity sensor and electric opening valve work together to feed back real-time monitoring data to the control system. The control system can dynamically adjust the water replenishment operation of the tar pool 1 and the water vapor diversion operation based on this data, thereby achieving precise control of the ratio of tar to condensed water and tar to water vapor in the entire system, ensuring stable operation of the system.

[0087] As mentioned above, in the gasification system provided by the present application, there are three main sources of condensed water (the third condenser 7, the first condenser 5, and the second condenser 6). As the gasification process continues, there may be an excess of condensed water in the system. To this end, a bypass and a drain valve can be set on the condensed water return pipe related to the first condenser 5 and the second condenser 6 to discharge excess condensed water as needed. Alternatively, the tar incineration device also includes a condensed water recovery tank, and the first condenser 5 and the second condenser 6 are connected to the condensed water recovery tank. The condensed water obtained by condensation can be discharged into the condensed water recovery tank, and then discharged as needed or replenished to the tar pool 1.

[0088] Optionally, the tar incineration device provided in the present application also includes a water replenishing mechanism, which is used to increase the proportion of water in the first mixture; the water replenishing mechanism includes: a water preparation tank, which is used to supply softened ordinary water; and a heater, which is used to preheat ordinary water so that the temperature of the ordinary water is close to the temperature of the tar in the tar pool 1.

[0089] Specifically, the reserve water tank is connected to the tar tank 1 via a pipeline and is equipped with a heater and a control valve. It also contains a softening resin tank or a reverse osmosis membrane device to remove calcium and magnesium ions and impurities from the water to prevent scaling. Alternatively, the reserve water tank is stored with deionized water. The heater can be a shell-and-tube heat exchanger or an electric heating rod.

[0090] Normal water is first softened (e.g., through ion exchange) to remove scaling ions like calcium and magnesium. This prevents them from reacting with the acidic substances in the tar to form precipitates, potentially clogging pipes or equipment. A heater heats the softened normal water to 60-80°C, matching the temperature of the tar in tar tank 1. The normal water is then slowly injected into tar tank 1 through a pipe. During mixing, the temperature difference between the water and tar is less than 5°C, preventing the tar from solidifying due to a sudden drop in temperature.

[0091] Optionally, a temperature sensor is further provided in the water reserve tank for detecting the water temperature to ensure that the temperature of the liquid used for water replenishment is close to the temperature of the tar in the tar pool 1 .

[0092] When the amount of condensed water in the system is insufficient, the water replenishment mechanism is activated as a backup water source. The preheated temperature of the softened water used for replenishment is close to the temperature of the return condensed water to avoid damaging the system temperature chain.

[0093] Specifically, when the density sensor in the tar tank 1 detects that the ratio of tar to water deviates from the set lower limit, and / or the viscometer detects that the viscosity of the first mixture does not meet the transportation requirements, the control system starts the water replenishment mechanism, the control valve of the water replenishment mechanism opens, and the preheated softened water in the water reserve tank is replenished into the tar tank 1 until the viscosity of the first mixture returns to normal.

[0094] Optionally, a heating layer is provided outside the tar pool 1 and / or a pipe connecting the tar pool 1 to the condensed water evaporator 2 to maintain the temperature of the first mixture.

[0095] In one embodiment, a heating layer is installed on the outer wall of the tar tank 1 and on the outer surface of the pipe connecting the tar tank 1 to the condensate evaporator 2. The heating layer is filled with insulating materials such as ceramic fiber wool and aerogel felt. The low thermal conductivity of the insulating material blocks the heat transfer path. The thickness of the insulating layer is 100 mm. A reflective layer (aluminum foil) is installed on the outer surface of the insulating layer. The reflective layer is 0.1 mm thick and has a reflectivity greater than 95%, which can reduce radiant heat loss. The outer wall of the heating layer is made of stainless steel sheet with a thickness of 1.5 mm or carbon steel with a thickness of 2 mm, which can protect the insulating material from moisture and mechanical damage. The uniform thickness of the insulating layer can prevent local cold spots that can cause tar solidification.

[0096] In another embodiment, only the pipe connecting the tar pool 1 to the condensed water evaporator 2 is provided with a heating layer. The heating layer adopts a heating paste or an electric heating structure.

[0097] For example, a heating patch is wrapped around the outer wall of the pipe and secured with pressure-sensitive adhesive. The heating patch converts electrical energy into heat energy to maintain the pipe temperature at all times and prevent condensation of the first mixture during transportation. In this case, a heating rod is provided within the tar pool 1 to maintain the temperature of the first mixture within the pool, while the heating patch maintains the temperature of the first mixture during transportation.

[0098] In another embodiment, the heating layer is connected to the heat source discharge pipeline of the condensate evaporator 2; the flue gas discharged from the condensate evaporator 2 enters the heating layer, which can maintain the temperature of the first mixture and prevent tar from condensing at low temperatures.

[0099] Specifically, a heating layer wraps around the outer wall of the tar pit 1 and also around the outside of the conveying pipe between the tar pit 1 and the condensate evaporator 2, forming a jacket structure. The heating layer is connected to the heat source discharge pipe of the condensate evaporator 2. The hot flue gas emitted by the tar direct-fired furnace 3 passes through the air heat exchanger 4 and the condensate evaporator 2 before entering the heating layer, indirectly heating the tar pit 1 and the conveying pipe for the first mixture. In this case, the flue gas in the heating layer also serves as a heat source for heating the first mixture (eliminating the need for a separate temperature control mechanism).

[0100] More specifically, the pipe wall of the heating layer is configured as a sandwich structure, and a thermal insulation material is provided in the sandwich to reduce heat loss.

[0101] The present application also provides a biomass raw material gasification system, including the above-mentioned tar incineration device, and also includes a gasifier, which can convert the biomass raw material into synthesis gas through high-temperature thermochemical reactions, accompanied by tar and water vapor; the tar direct-fired furnace 3 is equipped with a dual-fuel burner 3a, which can not only burn natural gas or diesel, but also burn the synthesis gas produced by the gasifier and the second mixture.

[0102] In one specific embodiment, the dual-fuel burner 3a adopts a multi-channel design, including: a central channel for conveying the second mixture; a middle channel for conveying synthesis gas; an outer channel for conveying backup fuels such as natural gas and diesel; a swirl air channel surrounding the central channel, middle channel and outer channel to provide tangential air flow to enhance the mixing effect; and an ignition system capable of simultaneously igniting multiple fuel combinations.

[0103] The dual fuel burner 3a includes four fuel mode switching logics.

[0104] Mode 1: Reserve fuel.

[0105] During the startup phase or when the system is under low load, natural gas or diesel is fed into the dual-fuel burner 3a and ignited by the electronic igniter to maintain the furnace temperature.

[0106] Mode 2: Second mixture.

[0107] When the tar pool 1 and the condensed water evaporator 2 are in stable operation, the second mixture (the ratio of tar to water vapor is 2:1-3:1) is fed into the dual-fuel burner 3a through the central channel and directly burned using the high temperature in the furnace without the need for additional ignition.

[0108] Mode 3: Synthesis gas.

[0109] The synthesis gas produced by the gasification furnace is fed into the dual-fuel burner 3a through the middle channel and mixed with air for combustion. At this time, the tar direct-fired furnace 3 can also clean the synthesis gas.

[0110] Mode 4: Synthesis gas and second mixture.

[0111] The synthesis gas and the second mixture are simultaneously fed into the dual-fuel burner 3a, and the high reactivity of the synthesis gas is utilized to promote the combustion of the tar, thereby achieving synergistic efficiency of the two fuels.

[0112] The dual-fuel burner 3a establishes a multi-fuel complementary technology system, compatible with natural gas, diesel, syngas, and tar, to address the diverse operating conditions of the gasification system. When the system is operating normally, the tar direct-fired furnace 3 can burn self-produced fuels such as syngas and tar, reducing reliance on external energy sources and maximizing biomass energy recovery.

[0113] The biomass raw material gasification system provided by the present application effectively solves the problems of difficult tar treatment, poor fuel adaptability and high dependence on external energy in traditional biomass gasification by integrating a tar incineration device and a dual-fuel burner 3a. The system realizes the harmless treatment and heat recovery of tar through a closed-loop process of mixing and viscosity reduction in the tar pool 1, quality improvement in the condensed water evaporator 2 and high-temperature incineration in the tar direct-fired furnace 3, thereby avoiding tar clogging pipelines and polluting the environment. The dual-fuel burner 3a supports flexible switching of multiple fuels such as natural gas, diesel, synthesis gas and tar, and can cope with the different needs of multiple operating conditions such as startup, low load and normal operation. At the same time, the dual-fuel burner 3a promotes tar cracking and improves combustion efficiency through the coordinated combustion of multiple fuels and the high reactivity of synthesis gas. It can also further clean and treat residual impurities in the synthesis gas when burning it. The system builds a closed-loop energy chain of "biomass raw materials → synthesis gas + tar → heat recovery", maximizes the recovery of biomass energy, reduces dependence on external fuels, and reduces overall energy consumption through cascade utilization of waste heat, achieving a stable, environmentally friendly and economical biomass gasification process.

[0114] Optionally, the biomass raw material gasification system provided in the present application also includes a third condenser 7, which is arranged on the discharge pipeline of the gasifier and is used to cool the gasification products discharged from the gasifier, so that the tar and water vapor in the gasification products are condensed into liquid; the condensed tar and condensed water enter the tar pool 1.

[0115] For details, please refer to Figure 1 In the illustrated embodiment, a gasification product discharge pipeline is provided at the outlet of the gasifier, and a third condenser 7 is provided on the gasification product discharge pipeline. The third condenser 7 can separate the gasification products so that the tar and water vapor therein are condensed into liquid and flow to the tar pool 1, while the synthesis gas flows to the tar direct-fired furnace 3.

[0116] The structure and use of the third condenser 7 are similar to those of the first condenser 5 and will not be described in detail.

[0117] It should be explained that there are two main sources of water vapor in the gasification products. One is the moisture contained in the biomass raw materials themselves, which evaporates into water vapor during the high-temperature thermochemical reaction in the gasifier (such as the dry distillation and pyrolysis process at 600-900°C); the other is the water generated by the gasification reaction, for example, the hydrogen and oxygen elements in the biomass combine to form H2O during the reaction, or the moisture brought in by the gasification agent (such as air, water vapor) does not fully participate in the reaction and remains.

[0118] The water vapor in the gasification product is condensed together with the tar to form a preliminary first mixture. After entering the tar pool 1, the system can adjust the ratio of tar to water to ensure the fluidity of the first mixture.

[0119] It should also be explained that after the gasification products enter the third condenser 7, they are cooled by a cooling medium (such as circulating cooling water or air) to below the dew point (e.g., 80-150°C). The water vapor in the gas releases latent heat due to the temperature drop, condensing from a gaseous state to liquid water. Tar (with a relatively high boiling point, typically >200°C) also condenses from a gaseous or aerosol state to a liquid state due to the temperature drop, forming a mixed liquid with the liquid water. Due to the significant difference in density, the mixed liquid and the uncondensed synthesis gas naturally separate. Due to its higher density, the mixed liquid settles to the bottom of the third condenser 7 and then flows through a pipeline into the tar pool 1. The synthesis gas, however, floats due to its lower density and is transported through another pipeline to the tar direct-fired furnace 3 or other utilization unit.

[0120] The third condenser 7 is usually equipped with components such as baffles and wire mesh demisters. By changing the direction of the airflow or increasing the gas-liquid contact area, it can enhance the droplet agglomeration and gas-liquid separation effects, ensuring that the tar content in the synthesis gas is reduced to below 1g / m³, meeting the needs of subsequent combustion or utilization.

[0121] Through temperature control and physical separation mechanism, the separation of tar, water and synthesis gas in the gasification products is achieved, which not only avoids tar entering the combustion system with synthesis gas and causing blockage or pollution, but also provides the prerequisite for the centralized recovery and resource utilization of tar.

[0122] Optionally, a cyclone separator is further provided on the gasification product discharge pipeline, and the cyclone separator is located upstream of the third condenser 7. The gasification product enters the cyclone separator tangentially at a speed of 15-25 m / s, generating centrifugal force, causing coarse particles of tar and ash to collide with the wall and then fall along the cone wall.

[0123] Setting up a cyclone separator to separate the coarse tar and ash can not only reduce the load of the subsequent third condenser 7, prevent a large amount of coarse impurities from entering it, reduce the risk of clogging of components such as baffles and heat exchange tubes, and extend the equipment maintenance cycle; it can also separate them in advance to prevent the coarse tar with high viscosity and many impurities from mixing with condensed water to form a high-viscosity slurry, thereby reducing pumping resistance. In addition, if the alkaline metal compounds such as potassium and sodium contained in the ash enter the tar direct-fired furnace 3, they are likely to melt and adhere to the furnace or the surface of the heat exchange tube at high temperature, forming slag, which affects the combustion efficiency and heat transfer effect. Separating the ash in advance can reduce the entry of such substances into the incineration system, reduce the risk of equipment corrosion and slagging, and at the same time improve the cleanliness of tar incineration and reduce the emission of pollutants in fly ash.

[0124] Optionally, a gas-liquid separator is further provided on the gasification product discharge pipeline, and is located downstream of the third condenser 7. After the condensed synthesis gas and mixed liquid enter the separator, the flow rate drops sharply to 0.1-0.3 m / s. The mixed liquid settles to the bottom due to the density difference and is discharged into the tar tank 1 through the liquid level control valve.

[0125] In a specific embodiment, referring to Figure 2 , a cyclone separator, a third condenser 7 and a gas-liquid separator are sequentially provided on the gasification product discharge pipeline. The cyclone separator first pre-treats the gasification product to separate the coarse particles of tar and ash, which can prevent a large amount of impurities from entering the subsequent equipment. Then, the third condenser 7 cools the gasification product after being treated by the cyclone separator, condenses the tar and water vapor therein into liquid, and realizes the preliminary separation of synthesis gas from liquid tar and water, laying the foundation for the subsequent utilization of synthesis gas and the recovery of tar. Finally, the gas-liquid separator further separates the mixed substances coming out of the third condenser, and accurately separates synthesis gas from tar and water based on the density difference, thereby ensuring the purity of synthesis gas and allowing synthesis gas to be more efficiently used for heating, power generation, etc., ensuring the smoothness of the entire gasification product processing process.

[0126] Optionally, a heat preservation or heating system is provided on the gasification product discharge pipeline (for details, please refer to the heating layer mentioned above) to control the temperature inside the pipeline to be greater than 150°C to prevent residual tar from condensing and clogging.

[0127] Optionally, the inner wall of the gasification product discharge pipeline is provided with an oleophobic coating (such as a nano-ceramic composite with a coating thickness of 50-100 μm) to reduce tar adhesion.

[0128] In one specific embodiment, the condensation temperature of the third condenser 7 is 80-150°C to separate the synthesis gas in the gasification product and condense the tar and water vapor into liquid; the temperature of the first mixture in the tar pool 1 is maintained at 60-80°C to prevent the tar from solidifying and ensure the fluidity of the first mixture; the operating temperature of the condensate evaporator 2 is 100-120°C to facilitate complete evaporation of water in the first mixture and gasify some light components in the tar while the heavy components remain in liquid form; the combustion temperature of the tar direct-fired furnace 3 is 1000-1200°C; the temperature of the hot flue gas discharged from the tar direct-fired furnace 3 is 600-800°C, the hot flue gas enters the air heat exchanger 4, and is cooled to 400-500°C after a primary heat exchange. The air is preheated to 300-450°C, and the cooled flue gas enters the condensate evaporator 2 and is cooled to 80-150°C after a secondary heat exchange.

[0129] Typical components of tar include benzene (boiling point 80°C), toluene (boiling point 110°C), naphthalene (boiling point 218°C), and polycyclic aromatic hydrocarbons (PAHs) (boiling point > 250°C). By utilizing the boiling point difference between tar and syngas (primarily composed of CO and H₂, with boiling points ranging from -191°C to -252°C), the gasification product is cooled to 80-150°C via the third condenser 7. While maintaining the gaseous state of the syngas, only a small amount of light components in the tar (such as benzene and toluene) may remain in a gaseous state, while the majority of components are condensed into a liquid state, facilitating the separation and collection of the tar. During this process, water vapor in the gasification product is liquefied along with the tar, forming a preliminary first mixture for subsequent processing.

[0130] Maintaining the temperature of the first mixture in the tar pool 1 at 60-80° C. can reduce the viscosity of the tar and meet the pumping requirements of the centrifugal pump.

[0131] The condensate evaporator 2 evaporates the water in the first mixture, upgrading the tar. At temperatures between 100°C and 120°C (slightly above the boiling point of water), the water is completely evaporated. Light components in the tar (boiling point <120°C), such as benzene and toluene, are vaporized along with the water vapor, while heavier components such as naphthalene and polycyclic aromatic hydrocarbons remain liquid, forming a second mixture containing light tar vapor, heavy tar droplets, and water vapor. This reduces tar viscosity, improves atomization, and enables more complete combustion, thereby reducing CO emissions and improving combustion efficiency. The upgraded second mixture has stable fluidity and can be transported over long distances, enhancing the system's flexibility and reliability.

[0132] Reference Figure 3The tar direct-fired furnace 3 operates at a temperature exceeding 1000°C to ensure complete combustion of the tar. It exhausts high-temperature flue gas at 600-800°C. This high-temperature flue gas enters the air heat exchanger 4, preheating the air used as the gasifying agent to a temperature of 300-450°C, meeting the gasifying agent's temperature requirements. The high-temperature flue gas then undergoes a primary heat exchange, cooling it to 400-500°C.

[0133] Continue to refer to Figure 3 The medium-temperature flue gas of 400-500°C discharged from the air heat exchanger 4 enters the condensate evaporator 2, so that the heat exchange temperature of the condensate evaporator 2 reaches 100-120°C, so as to evaporate the water in the first mixture; the medium-temperature flue gas undergoes secondary heat exchange and is cooled to 80-150°C.

[0134] The low-temperature flue gas of 80-150° C. discharged from the condensate evaporator 2 can be discharged directly through the chimney, or can be input into the dryer or waste heat boiler for reuse of waste heat.

[0135] After the flue gas passes through the condensate evaporator 2 and undergoes secondary heat exchange to a temperature of 80-150°C, the low-temperature flue gas just meets the heating requirements of the tar pool 1. At this point, the low-temperature flue gas can also be introduced into the heating layer, using the flue gas's residual heat to maintain the temperature in the tar pool 1 at 60-80°C, ensuring that the tar remains liquid and fluid.

[0136] By utilizing the gradient of waste heat, the originally emitted low-temperature flue gas is converted into a heat source for the tar pool 1, which not only avoids additional energy consumption (such as adding a temperature control mechanism), but also prevents tar from solidifying and clogging the pipeline, thereby maximizing the energy efficiency of the system.

[0137] Optionally, the low-temperature flue gas enters the heating layer to heat or insulate the first mixture. After three heat exchange cycles, the low-temperature flue gas is further cooled, becoming cold flue gas. This cold flue gas can be recirculated into the tar direct-fired furnace 3 to regulate the combustion temperature, or to regulate the temperature of the high-temperature flue gas discharged from the tar direct-fired furnace 3. The cold flue gas not recirculated is discharged through the chimney.

[0138] Through the dynamic mixing of cold flue gas and high-temperature flue gas, precise control of the hot flue gas temperature is achieved, which can avoid thermal stress damage to subsequent equipment such as the air heat exchanger 4 due to excessive temperature, and ensure the stable operation of the system and the waste heat recovery efficiency.

[0139] If necessary, the cold flue gas can also be mixed into the air heat exchanger 4 to adjust the temperature of the medium-temperature flue gas to meet the use requirements of the condensate evaporator 2.

[0140] The above embodiments merely illustrate several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A tar incineration device, characterized in that: include: A tar pool (1) for storing tar, wherein the tar can be mixed with condensed water in the tar pool (1) to form a first mixture that is convenient for circulation in the pipeline; A condensed water evaporator (2) is connected to the tar pool (1), and after the first mixture enters the condensed water evaporator (2), the condensed water therein is evaporated into water vapor, and the water vapor and the tar form a second mixture; A tar direct-fired furnace (3) is connected to the condensed water evaporator (2), and the second mixture enters the tar direct-fired furnace (3) and is burned to generate hot flue gas; An air heat exchanger (4) is connected to the tar direct-fired furnace (3), and hot flue gas enters the air heat exchanger (4) and serves as a heat source for the air heat exchanger (4). The hot flue gas can preheat the air, and the obtained hot air can be used as a gasifying agent for the gasifier; The flue gas, after passing through the air heat exchanger (4) and completing a heat exchange, flows to the condensed water evaporator (2) and serves as a heat source for the condensed water evaporator (2).

2. The tar incineration device according to claim 1, characterized in that: The tar pool (1) is equipped with: A temperature control mechanism for regulating the temperature of the first mixture in the tar pool (1) so as to maintain the first mixture at 60-80°C; and / or, a density sensor for monitoring the density of the first mixture, thereby inferring the ratio of tar to water therein; and / or, a viscometer for monitoring the viscosity of the first mixture to ensure that it meets the delivery requirements; and / or, a stirrer for stirring the first mixture to prevent tar precipitation and agglomeration.

3. The tar incineration device according to claim 1, characterized in that: The invention also includes a first condenser (5), which is arranged on the heat source discharge pipeline of the condensed water evaporator (2) and is used to condense water vapor in the flue gas passing through the condensed water evaporator (2) to obtain condensed water, and the condensed water can flow back into the tar pool (1).

4. The tar incineration device according to claim 1, characterized in that: The second condenser (6) is provided on the heat exchange material discharge pipeline of the condensed water evaporator (2) and is used for condensing water vapor in the second mixture discharged through the condensed water evaporator (2) to obtain condensed water, and the condensed water can flow back into the tar pool (1); By diverting the second condenser (6), the proportion of water vapor in the second mixture can also be reduced, thereby preventing the water vapor from interfering with the combustion of tar.

5. The tar incineration device according to claim 4, characterized in that: In the tar pool (1), the ratio of tar to water is 1:1-1:3; After the water vapor is diverted through the second condenser (6), the second mixture enters the tar direct-fired furnace (3), and the ratio of tar to water vapor is 2:1-3:

1.

6. The tar incineration device according to claim 5, characterized in that: It also includes a water replenishing mechanism, which is used to increase the proportion of water in the first mixture; The water replenishment mechanism comprises: Water reserve tank, used to supply softened ordinary water; A heater is used to preheat the ordinary water so that the temperature of the ordinary water is close to the temperature of the tar in the tar pool (1).

7. The tar incineration device according to any one of claims 1 to 6, characterized in that: The tar pool (1) and / or the pipe connecting the tar pool (1) to the condensed water evaporator (2) is provided with a heating layer outside; The heating layer is connected to the heat source discharge pipeline of the condensed water evaporator (2); The flue gas discharged from the condensed water evaporator (2) enters the heating layer, and is capable of maintaining the temperature of the first mixture.

8. A biomass raw material gasification system, characterized in that: A tar incineration device according to any one of claims 1 to 7, further comprising a gasifier capable of converting biomass raw materials into synthesis gas through a high-temperature thermochemical reaction, accompanied by tar and water vapor; The tar direct-fired furnace (3) is equipped with a dual-fuel burner (3a), and the dual-fuel burner (3a) is capable of burning not only natural gas or diesel, but also the synthesis gas generated by the gasifier and the second mixture.

9. The biomass raw material gasification system according to claim 8, characterized in that: The apparatus further comprises a third condenser (7), the third condenser (7) being arranged on the discharge pipeline of the gasifier and being used to cool the gasification product discharged from the gasifier so that the tar and water vapor in the gasification product are condensed into a liquid state; The condensed tar and condensed water enter the tar pool (1).

10. The biomass raw material gasification system according to claim 9, characterized in that: The condensation temperature of the third condenser (7) is 80-150°C, so as to separate the synthesis gas in the gasification product and condense the tar and water vapor into liquid form; The temperature of the first mixture in the tar pool (1) is maintained at 60-80°C to prevent the tar from solidifying and ensure the fluidity of the first mixture; The operating temperature of the condensed water evaporator (2) is 100-120°C, so that the water in the first mixture is completely evaporated and part of the light components in the tar are gasified while the heavy components remain in liquid form; The combustion temperature of the tar direct-fired furnace (3) is 1000-1200°C; The temperature of the hot flue gas discharged from the tar direct-fired furnace (3) is 600-800°C. The hot flue gas enters the air heat exchanger (4) and is cooled to 400-500°C after a primary heat exchange. The air is preheated to 300-450°C. The cooled flue gas enters the condensed water evaporator (2) and is cooled to 80-150°C after a secondary heat exchange.

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