A molten gasification system and method for gasification treatment of carbon-containing hazardous waste

Abstract

The application provides a molten gasification furnace for carbon-containing hazardous waste gasification treatment, the molten gasification furnace is hollow, and a gasification chamber, a molten slag pool and a slag pool are sequentially arranged from top to bottom; the gasification chamber is communicated with the molten slag pool; the molten slag pool is provided with a molten slag outlet, and the molten slag pool is communicated with the slag pool through the molten slag outlet; the top of the gasification furnace is provided with a material inlet; the sidewall of the gasification chamber is provided with a plurality of burners, the burners can provide gas and / or liquid into the gasification chamber; the sidewall of the gasification chamber close to the top of the molten slag pool is provided with a plurality of preheating burners, the preheating burners can heat the molten slag in the molten slag pool to a molten state; the sidewall of the slag pool is provided with a cooling water inlet and a cooling water outlet, so that the cooling water can cool and shock the molten slag falling into the slag pool to form water vapor. The molten gasification system can be used for treating various carbon-containing hazardous wastes, has high gasification efficiency, high stability and does not need to additionally treat raw materials.

Description

Technical Field

[0001] This invention relates to the field of gasification engineering technology, and in particular to a molten gasification system and method for treating carbon-containing hazardous waste. Background Technology

[0002] Hazardous waste refers to solid, liquid, or other forms of waste that are listed in the "National Hazardous Waste List" or identified according to national hazardous waste identification standards and methods as possessing one or more hazardous characteristics such as corrosivity, toxicity, flammability, and reactivity. Hazardous waste disposal technologies include incineration, non-incineration, and secure landfill. Carbon-containing hazardous waste (referred to as "carbon-containing hazardous waste") refers to carbon-containing hazardous waste generated in industry and daily life that is harmful to human health and the environment, such as industrial sludge, spent catalyst wax residue, and pond waste.

[0003] Currently, the disposal of carbon-containing hazardous waste generally involves incineration, but incineration produces secondary pollution such as dioxins and generates carbon emissions. Waste gasification technology is a clean utilization technology that can reduce the emission of pollutants such as dioxins. It includes methods such as direct gasification, melt gasification, RDF co-gasification, coal co-gasification, and waste gasification for fuel gas production. Waste gasification technology uses gasification to melt and decompose waste at high temperatures. Organic matter in the waste can be converted into syngas (mainly CO and H2), while inorganic matter can be converted into vitreous ash. Using gasification technology to treat carbon-containing hazardous waste allows the carbonaceous matrix to be converted into syngas for the production of downstream high-value chemicals, turning waste into valuable resources.

[0004] Currently, there are many types of gasification technologies, but the sources of carbon-containing hazardous waste are complex and varied, existing in multiple forms such as liquid, solid, and gas, with different transport properties. This leads to problems in the stable operation of gasifiers and prevents effective improvement in gasification intensity. In existing technologies, the waste residue generated after molten gasification is often discharged from the slag outlet in liquid form. Due to rapid cooling, the slag outlet is prone to blockage, and residual carbon easily accumulates on the surface of the molten slag, resulting in excessively high residual carbon content in the slag and affecting gasification efficiency. Existing gasifiers face the problem of raw material transportation, with requirements on the viscosity, slurry-forming properties, and particle size of solid waste, which greatly limits the applicability of raw materials.

[0005] Chinese patent CN214275740U discloses a system for the high-temperature gasification and melting co-processing of three-phase waste. To ensure smooth material feeding and discharging and prevent blockage in the fluidized bed, the system has fine particulate material inlets, liquid waste inlets, and gaseous waste inlets distributed throughout the fluidized bed. The solid material entering the fluidized bed undergoes pretreatment, with the resulting fine particulate material having a calorific value ≥1800 kcal / kg, a moisture content ≤30%, and a particle size ≤1 mm. However, this pretreatment increases energy consumption and the complexity of the device. The multiple material inlets also require pre-separation, further increasing the device's complexity and hindering large-scale application. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a molten gasification system for the gasification treatment of carbon-containing hazardous waste. It can be used for the treatment of carbon-containing hazardous waste in various physical states, and features high gasification efficiency, strong stability, and no need for additional processing of raw materials.

[0007] The first aspect of the present invention provides a molten gasification furnace for the gasification treatment of carbon-containing hazardous waste. The molten gasification furnace is hollow and has a gasification chamber, a molten slag pool, and a slag pool arranged sequentially from top to bottom. The gasification chamber and the molten slag pool are in communication. The molten slag pool has a molten slag outlet, and the molten slag pool and the slag pool are connected through the molten slag outlet. A synthesis gas outlet is provided at the top of the molten gasification furnace. Several burners are provided on the side wall of the gasification chamber, which can supply gas and / or liquid into the gasification chamber. A material inlet is provided at the top of the gasification furnace. The carbon-containing hazardous waste to be treated enters the gasification chamber through the material inlet to undergo a gasification reaction. The molten slag obtained after the reaction enters the molten slag pool. Several preheating burners are provided on the side wall of the gasification chamber near the top of the molten slag pool, which can heat the molten slag in the molten slag pool to a molten state. A cooling water inlet and a cooling water outlet are provided on the side wall of the slag pool, so that the cooling water can quench the molten slag falling into the slag pool to form water vapor.

[0008] Preferably, the bottom of the slag pool is concave, and the horizontal position of the slag outlet is at least higher than the most concave part of the slag pool.

[0009] Preferably, the depth of the slag pool is not less than 0.5m, and the liquid surface area that can be formed in the slag pool is not less than 3m². 2 The trapezoidal side of the slag pool forms an acute angle of 45-60° with the bottom horizontal line.

[0010] Preferably, the bottom of the slag pool is a concave trapezoid, and the slag outlet is located on one side of the trapezoid.

[0011] Preferably, the slag pool is pre-filled with cooling water.

[0012] Preferably, the preheating burner is tilted downwards, and the angle between the preheating burner and the horizontal line is 40-75°.

[0013] Preferably, a material buffer tank is connected above the material inlet.

[0014] Preferably, the burner is an annular three-channel burner, which includes, from the inside out, a combustion-supporting agent channel, a fuel channel, and a water-cooling channel, and the water-cooling channel is not connected to the gasification chamber.

[0015] Preferably, the bottom of the slag pool is provided with a slag outlet.

[0016] A second aspect of the present invention provides a method for melting and gasifying carbon-containing hazardous waste, implemented using the melting and gasifying furnace described above, comprising the following steps:

[0017] S1, the carbon-containing hazardous waste to be treated is sent into the gasification chamber through the material inlet, and the material is heated to 800-1000℃ through the burner to carry out the first gasification reaction and generate syngas;

[0018] S2, the slag enters the slag pool and is heated to a molten state. The molten slag in the liquid state undergoes a second gasification reaction with the fuel that enters the gasification chamber through the burner on the liquid surface to generate syngas;

[0019] S3, when the liquid level in the slag pool exceeds the slag outlet, the excess slag enters the slag pool from the slag outlet. The cooling water entering the slag pool through the cooling water inlet cools the high-temperature slag to form water vapor. The water vapor reacts with the syngas in the molten gasifier to produce modified syngas. The modified syngas is discharged from the syngas outlet at the top of the molten gasifier.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] The molten gasification furnace described in this invention is used for the gasification treatment of carbon-containing hazardous waste. It creatively combines a fluidized bed with a molten slag bubbling system. A molten slag pool is set below the gasification chamber to provide reaction space for solid waste. Burners that can provide gaseous or liquid waste are set on both sides of the gasification chamber. Gas and / or liquid gasification reactions can be carried out in the space of the gasification chamber, realizing the direct gasification treatment of multiple physical states (gas, liquid, and solid) of raw materials at the same time, and the requirements for raw material transportation are not high.

[0022] This invention incorporates a slag pool within the molten gasifier. Solid carbonaceous hazardous waste enters the slag pool and melts. Due to its density, the carbonaceous matrix is ​​concentrated in the upper part of the slag pool. At the liquid surface, the carbonaceous matrix has a longer residence time and can fully contact the gasifying agent, achieving a higher conversion rate and increasing the organic matter reaction rate by approximately 30%. Simultaneously, the slag pool effectively improves the stability of the molten gasifier, reducing shutdown frequency to approximately 50% of that of conventional gasifiers (3-4 times / year).

[0023] The molten gasification furnace described in this invention can modulate the syngas during the gasification reaction. The high-temperature molten slag is cooled by cooling water in the slag pool to generate water vapor. The water vapor reacts with the syngas in the molten gasification furnace to form a water-gas reaction, adjusting the CO and H2 ratio of the syngas. The modulated syngas can be directly obtained from the syngas outlet located at the top, which helps to improve the efficiency of subsequent syngas purification treatment. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the melting gasification furnace described in this invention;

[0025] Figure 2 This is a schematic diagram of a specific structure of the burner described in this invention;

[0026] Figure 3 The diagram shows the gasification state of the solid carbonaceous matrix in Experiment Example 1 at 0s, 60s, and 120s.

[0027] Figure 4 The diagram shows the vaporization state of the solid carbonaceous matrix in Experiment Example 1 at 0s, 60s and 90s on the surface of the molten slag.

[0028] Among them, 100 is the melting gasification furnace, 110 is the gasification chamber, 111 is the material inlet, 112 is the synthesis gas inlet, 113 is the first burner, 1131 is the combustion aid channel, 1132 is the fuel channel, 1133 is the cooling water channel, 1134 is the cooling water channel inlet, 1135 is the cooling water channel outlet, 1136 is the fuel channel inlet, 1137 is the combustion aid channel inlet, 114 is the second burner, 115 is the first preheating burner, 116 is the second preheating burner, 120 is the slag pool, 121 is the slag outlet, 130 is the slag pool, 131 is the cooling water inlet, 132 is the cooling water outlet, 140 is the slag outlet, and 150 is the material buffer tank. Detailed Implementation

[0029] The technical solution of the present invention will now be described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them; and the structures shown in the accompanying drawings are merely illustrative and do not represent physical objects. It should be noted that all other embodiments obtained by those skilled in the art based on these embodiments of the present invention are within the scope of protection of this application.

[0030] In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0031] Figure 1 The present invention illustrates the specific structure of a molten gasification furnace for the gasification treatment of carbon-containing hazardous waste. The molten gasification furnace 100 is hollow inside and has a gasification chamber 110, a molten slag pool 120 and a slag pool 130 arranged sequentially from top to bottom. The top of the molten gasification furnace has a material inlet 150 and the bottom has a slag outlet 140. The gasification chamber 110 and the molten slag pool 120 are connected.

[0032] In this invention, the gasification chamber 110 is used for the gasification reaction to generate syngas, and water vapor or the like is used to adjust the CO / H2 ratio of the syngas. Several burners are provided on the side wall of the gasification chamber, which are used to heat the gasification chamber. Figure 1 In the illustrated molten gasification furnace, two burners, namely a first burner 113 and a second burner 114, are symmetrically arranged on the side wall of the gasification chamber. Both burners are horizontally positioned with their outlets facing the gasification chamber. In this invention, the burner structure can be a three-channel structure. Figure 2 Taking the first burner 113 as an example, a specific structure is shown, which includes, from the inside out, a ring-shaped combustion-supporting agent channel 1131, a fuel channel 1132, and a water-cooling channel 1133. The combustion-supporting agent channel 1131 has a combustion-supporting agent channel inlet 1137 at its far end for the combustion-supporting agent to enter, which can be oxygen. The fuel channel 1132 has a fuel inlet 1136 at its far end for the fuel to enter. The fuel includes, but is not limited to, coke oven gas, methane, industrial off-gas, or substances such as diesel and ethanol. The inner diameter of the outlet ends of the combustion-supporting agent channel 1131 and the fuel channel 1132 gradually decreases and is inclined towards the center. The water-cooling channel 1133 is not connected to the gasification chamber 110. Cooling water flows in the water-cooling channel to cool the burner. The water-cooling channel 1133 has a cooling water channel inlet 1134 above its far end and a cooling water channel outlet 1135 below its far end.

[0033] In this invention, a number of preheating burners are provided on the side wall of the gasification chamber 110 near the top of the slag pool 120. The preheating burners can heat the slag in the slag pool to a molten state. Figure 1In the molten gasification furnace shown, two downward-sloping preheating burners, namely the first preheating burner 115 and the second preheating burner 116, are symmetrically arranged on the side wall of the gasification chamber 110 near the top of the molten slag pool 120. The preheating burners can also be a three-channel structure, as detailed in [reference needed]. Figure 2 As described above. The preheating burner in this invention is used to heat and melt the slag pool during the molten gasification start-up phase. Once the system is running stably, the preheating burner can be shut down. In this invention, oxygen is introduced through the burner or preheating burner via the central combustion aid channel 1131, and fuel is introduced through the combustion aid channel 1132. Combined with the narrowing of the outlet end of the three-channel structure, the fuel is introduced in the form of a reverse-diffusion flame. In some preferred embodiments, when the angle between the preheating burner and the horizontal line is 40-75° and the thickness between the combustion aid channel 1131 and the fuel channel 1132 at the outlet end of the preheating burner is less than 0.5 cm, it ensures that the preheating burner forms a stable flame, reduces preheating burner erosion, and prevents erosion of the slag pool wall during system startup. The solid slag melts within the slag pool, ultimately forming a stable liquid slag interface.

[0034] In this invention, the slag pool 120 is a concave type with an open top to hold a certain amount of molten slag, so that carbonaceous substances float to the liquid surface and react with the gasifying agent, thereby improving the gasification efficiency. Figure 1 In the molten gasification furnace shown, the bottom of the slag pool 120 is a concave inverted trapezoid, the depth of the slag pool is 0.5m, and the liquid surface area that can be formed in the slag pool is not less than 3m². 2 The trapezoidal side of the slag pool forms an acute angle of 45-60° with the bottom horizontal line. A slag outlet 121 is provided on one side of the trapezoid. The slag outlet 121 is a vertical opening, and the slag pool 120 and the slag pool 130 are connected through the slag outlet 121. When the liquid level in the slag pool is higher than the slag outlet 121, the excess slag flows out from the slag outlet 121 into the slag pool 130 below. It is cooled by the cooling water injected into the slag pool 130 to generate water vapor. The water vapor rises from the slag outlet 121 and reacts with the syngas generated in the gasification chamber to adjust the CO and H2 content in the syngas. This allows the syngas to be adjusted once during the preparation process, which helps to simplify the subsequent syngas purification process.

[0035] In this invention, the slag pool 130 is used to receive high-temperature molten slag and generate water vapor through quenching. Figure 1In the molten gasifier shown, a cooling water inlet 131 is provided on the upper side wall of the slag pool 130, and a cooling water outlet 132 is provided on its lower side wall, allowing cooling water to continuously enter and exit. For ease of use, a certain amount of liquid can be pre-filled into the slag pool 130 to cool the high-temperature molten slag, improving the operating efficiency of the device. A slag outlet 140 is provided at the bottom of the slag pool 130, allowing waste residue to be directly discharged from the bottom of the molten gasifier. The residue is discharged in solid form, reducing the risk of blockages that occur with liquid slag discharge, effectively improving the operational stability of the molten gasifier and reducing the number of shutdowns. Compared to conventional gasifiers that shut down 3-4 times a year, the molten gasifier described in this invention shuts down less than half the number of times.

[0036] In some specific embodiments of the present invention, a material buffer tank 150 is also provided above the top material inlet of the molten gasification furnace. Solid materials can be pre-stored in the material buffer tank 150 and supplied according to the required feeding rate.

[0037] A second aspect of the present invention provides a method for melting and gasifying carbon-containing hazardous waste, implemented using the melting and gasifying furnace described above, comprising the following steps:

[0038] S1, the carbon-containing hazardous waste to be treated is sent into the gasification chamber through the material inlet, and the material is heated to 800-1000℃ through the burner to carry out the first gasification reaction and generate syngas;

[0039] S2, the slag enters the slag pool and is heated to a molten state. The molten slag in the liquid state undergoes a second gasification reaction with the fuel that enters the gasification chamber through the burner on the liquid surface to generate syngas;

[0040] S3, when the liquid level in the slag pool exceeds the slag outlet, the excess slag enters the slag pool from the slag outlet. The cooling water entering the slag pool through the cooling water inlet cools the high-temperature slag to form water vapor. The water vapor reacts with the syngas in the molten gasifier to produce modified syngas. The modified syngas is discharged from the syngas outlet at the top of the molten gasifier.

[0041] Experimental Example 1

[0042] This experiment is used to verify the gasification reaction efficiency of the molten gasification furnace described in this invention.

[0043] A simulation experiment was conducted in a square molten slag bath in the laboratory. The bottom of the square molten slag bath was 10cm. 2 ×10cm 2 A square with a height of 1cm.

[0044] The experiment was divided into two groups. The experimental group had molten slag placed in a square slag pool in the laboratory beforehand, while the control group had an equal amount of Yangchangwan coal particles placed in a square slag pool in the laboratory.

[0045] Using 1g of "Yangchangwan Coal," a typical coal used for gasification, as raw material, the following experiments were conducted in the slag pools of the experimental and control groups: the slag pools were heated from room temperature to 1300℃ at a rate of 100℃ / min. During the heating process, CO2 gasifying agent was continuously introduced to simulate the atmosphere and raw material supply in an industrial environment. The gasification state of the carbonaceous matrix was monitored and recorded in real time using a high-temperature visualization system. The results are as follows: Figure 3 , 4 As shown.

[0046] Figure 3 The diagram shows the gasification state of a solid carbonaceous matrix at 0s, 60s, and 120s. Figure 4 The diagram shows the vaporization state of the solid carbonaceous matrix at the molten slag surface at 0s, 60s, and 90s. It can be seen that the solid carbonaceous matrix alone vaporizes for about 120s, while the reaction time on the molten slag wall is about 90s, indicating a significantly faster reaction time.

[0047] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A melting gasification furnace for the gasification treatment of carbon-containing hazardous waste, characterized in that, The molten gasifier is hollow inside and has a gasification chamber, a molten slag pool, and a slag pool arranged sequentially from top to bottom; the gasification chamber and the molten slag pool are connected; the molten slag pool has a molten slag outlet, and the molten slag pool and the slag pool are connected through the molten slag outlet; a syngas outlet is provided at the top of the molten gasifier. The gasifier is equipped with a material inlet at the top; two burners are symmetrically arranged on the side wall of the gasification chamber. The two burners are horizontally arranged and their outlets face the gasification chamber. The burners can supply gas and / or liquid into the gasification chamber. On the side wall of the gasification chamber near the top of the molten slag pool, there are two downward-sloping preheating burners symmetrically arranged. The preheating burners can heat the molten slag in the molten slag pool to a molten state. The preheating burners heat and melt the molten slag pool during the start-up stage of melting and gasification. After the system is running stably, the preheating burners can stop working. The bottom of the slag pool is a concave inverted trapezoid, and the slag outlet is located on one side of the trapezoid. The slag outlet is a vertical opening, and the slag pool and the slag pool are connected through the slag outlet. The horizontal position of the slag outlet is at least higher than the most concave point of the slag pool. The depth of the slag pool is not less than 0.5m, and the liquid surface area that can be formed in the slag pool is not less than 3m². 2 The trapezoidal side of the slag pool forms an acute angle of 45-60° with the bottom horizontal line; The slag pool is equipped with a cooling water inlet and a cooling water outlet on its side wall. The cooling water is used to cool the molten slag falling into the slag pool and generate water vapor. When the liquid level in the molten slag pool is higher than the molten slag outlet, the excess molten slag flows out from the molten slag outlet into the slag pool below. It is then cooled by the cooling water injected into the slag pool to generate water vapor. The water vapor rises from the molten slag outlet and reacts with the syngas generated in the gasification chamber to adjust the CO and H2 content in the syngas, so that the syngas can be modified once during the preparation process. The burner and preheating burner are annular three-channel burners, which include, from the inside out, a combustion-supporting agent channel, a fuel channel, and a water-cooling channel. The water-cooling channel is not connected to the gasification chamber. The combustion-supporting agent is oxygen. The fuel is selected from at least one of coke oven gas, methane, industrial off-gas, diesel, and ethanol. The inner diameter of the outlet ends of the combustion-supporting agent channel and the fuel channel gradually decreases and slopes towards the center. The burner or preheating burner allows the fuel to be introduced in the form of a reverse diffusion flame. The preheating burner is tilted downwards, with an angle of 40°-75° between the preheating burner and the horizontal line. The thickness between the combustion aid channel and the fuel channel at the outlet end of the preheating burner is less than 0.5cm. The preheating burner forms a stable flame that detaches from the flame. The solid slag is heated and melted in the slag pool to eventually form a stable liquid slag interface.

2. The melting gasification furnace according to claim 1, characterized in that, The slag pool is pre-filled with cooling water.

3. The melting gasification furnace according to claim 1, characterized in that, A material buffer tank is connected above the material inlet.

4. The melting gasification furnace according to claim 1, characterized in that, The slag pool is equipped with a slag outlet at the bottom.

5. A method for melting and gasifying carbon-containing hazardous waste, characterized in that, The process, achieved using the melting gasification furnace according to any one of claims 1-4, includes the following steps: S1, the carbon-containing hazardous waste to be treated is sent into the gasification chamber through the material inlet, and the material is heated to 800-1000℃ through the burner to carry out the first gasification reaction and generate syngas; S2, the slag enters the slag pool and is heated to a molten state. The molten slag in the liquid state undergoes a second gasification reaction with the fuel that enters the gasification chamber through the burner on the liquid surface to generate syngas; S3, when the liquid level in the slag pool exceeds the slag outlet, the excess slag enters the slag pool from the slag outlet. The cooling water entering the slag pool through the cooling water inlet cools the high-temperature slag to form water vapor. The water vapor reacts with the syngas in the molten gasifier to produce modified syngas. The modified syngas is discharged from the syngas outlet at the top of the molten gasifier.

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