A biomass cascade gasification gas making device

Abstract

This application discloses a biomass cascade gasification gasification device, relating to the field of biomass gasification. The primary gasification system uses superheated steam and oxygen as gasifying agents, offering strong raw material adaptability; it can use biomass briquettes or regular bulk biomass, resulting in low raw material pretreatment costs. A fluidization device ensures a uniform temperature field in the primary gasifier, reducing the likelihood of coking. A return feeder returns semi-coke particles separated by a cyclone separator to the primary gasifier, allowing them to participate in the gasification reaction again, improving biomass raw material utilization and reducing semi-coke ash emissions. Based on this, the primary gasification system can reduce raw material pretreatment costs and semi-coke ash emissions. The secondary gasification system introduces pure oxygen and uses non-catalytic oxidation technology to remove impurities carried in the crude syngas through high-temperature cracking. A quench device cools the high-temperature crude syngas, reducing dust and ash accumulation and facilitating subsequent waste heat recovery. Based on this, the secondary gasification system can reduce the impurity content in the crude syngas and lower the crude syngas purification cost.

Description

Technical Field

[0001] This application relates to the field of biomass gasification, and in particular to a biomass cascade gasification gasification device. Background Technology

[0002] The utilization of biomass mainly employs physical / chemical conversion technologies. Traditional utilization methods primarily include agricultural and livestock feed, biomass return to the field, biomass incineration power generation, and fermentation to produce biogas. These traditional technologies are characterized by small scale, low energy efficiency, low product added value, and poor economic benefits. Gasification technology, on the other hand, features high energy efficiency, large scale, and high product added value. Gasification technologies are mainly divided into fixed-bed gasification technology, fluidized-bed gasification technology, and entrained-flow gasification technology.

[0003] Biomass feedstocks are characterized by low carbon content, low calorific value, low ash melting point, high volatile matter content, and poor fluidity. Using entrained flow technology results in complex and costly feedstock pretreatment, leading to poor economic efficiency. Fixed-bed technology faces challenges in bed stabilization, high feedstock pretreatment costs, high impurity content at the outlet, and complex composition, also resulting in poor economic efficiency. Fluidized bed technology offers simple feedstock pretreatment and low cost, but also results in relatively high impurity content and complex composition at the outlet. All three gasification technologies have limitations, either due to high feedstock pretreatment costs or high impurity content in the crude syngas.

[0004] Therefore, how to reduce the cost of raw material pretreatment and the impurity content in crude syngas is a problem that needs to be solved by those skilled in the art. Utility Model Content

[0005] The purpose of this application is to provide a biomass cascade gasification gasification device to address the limitations of gasification technology, such as high raw material pretreatment costs or high impurity content in crude syngas.

[0006] To solve the above-mentioned technical problems, this application provides a biomass cascade gasification gasification device, comprising: a primary gasification system and a secondary gasification system;

[0007] The primary gasification system includes a primary gasifier, a feeding device, a fluidizing device, a cyclone separator, and a return feeder. The feeding device is connected to the primary gasifier and is used to feed biomass feedstock into the primary gasifier. The fluidizing device is located at the bottom of the primary gasifier and is used to feed pure oxygen and superheated steam into the primary gasifier. The inlet of the cyclone separator is connected to the near-top of the primary gasifier, and the outlet of the cyclone separator is connected to the near-bottom of the primary gasifier through the return feeder. The cyclone separator is used to separate semi-coke particles from the crude syngas generated by the gasification reaction in the primary gasifier. The return feeder is used to return the semi-coke particles to the primary gasifier. The secondary gasification system includes a secondary gasifier, a gasifying agent injection device, and a quench device. The secondary gasifier is connected to the cyclone separator. The gasifying agent injection device is located at the top of the secondary gasifier and is used to inject pure oxygen into the secondary gasifier. The quench device is located at the bottom of the secondary gasifier and is used to remove dust and cool the crude syngas.

[0008] In one feasible embodiment, the feeding device includes a hopper, a discharge pipe, an anti-blocking device, and a screw feeder. The hopper is located above the screw feeder. One end of the discharge pipe is connected to the bottom of the hopper, and the other end of the discharge pipe is connected to the first end of the screw feeder. The second end of the screw feeder is connected to the primary gasifier. The anti-blocking device is used to ensure that the material continuously enters the screw feeder.

[0009] In one feasible embodiment, the fluidization device includes a feed cylinder, a central fluidizer, branch fluidizing pipes, and branch fluidizers. The feed cylinder is connected to the bottom of the primary gasifier. The central fluidizer is located at the top neck of the feed cylinder. A plurality of branch fluidizing pipes are arranged on the side wall near the top of the feed cylinder, and each branch fluidizing pipe is equipped with a branch fluidizer.

[0010] In one feasible embodiment, the furnace wall of the primary gasifier is composed of refractory and wear-resistant castable, lightweight insulation material, and thermal insulation material from the inside out.

[0011] In one feasible embodiment, the quenching device includes a quenching chamber, a quenching pipe, a quenching spray gun, a circulating water cooling pipe, and a slag flushing water nozzle. The top of the quenching chamber is connected to the bottom of the secondary gasifier. A plurality of quenching spray guns are distributed circumferentially along the top of the quenching chamber. The quenching pipe is connected to the quenching spray gun. The circulating water cooling pipe and the slag flushing water nozzle are located at the bottom of the quenching chamber.

[0012] In one feasible embodiment, the system further includes a waste heat recovery and dust removal system, which comprises a radiant waste boiler, an evaporator, a dust collector, and an economizer connected in sequence, wherein the inlet of the radiant waste boiler is connected to the outlet of the quench chamber of the quenching device.

[0013] In one feasible embodiment, the radiant waste boiler includes a boiler drum, a first channel, a second channel, and a screen-type superheater. Both the first channel and the second channel are made of molded walls. The second channel is located between the first channel and the screen-type superheater. The bottom of the first channel and the bottom of the second channel are connected. The top of the first channel is connected to the top of the screen-type superheater. The screen-type superheater includes a screen-type superheating zone and a convection evaporation zone. The screen-type superheating zone is located above the convection evaporation zone. The boiler drum is connected to the top of the first channel, the top of the first channel, the screen-type superheating zone, and the convection evaporation zone. The screen-type superheater is connected to the evaporator.

[0014] In one feasible embodiment, a slag discharge device is provided at the bottom of the fluidizing device, the bottom of the quenching device, and the bottom of the radiant waste pot.

[0015] In one feasible embodiment, the slag discharge device includes a slag discharge chute, a screw conveyor, a slag cooler, and an auxiliary cooling device. The slag discharge chute is connected to the screw conveyor, the slag cooler is used to cool the ash and slag inside the screw conveyor, and the auxiliary cooling device is used to provide a cooling medium for the slag cooler.

[0016] In one feasible embodiment, the slag discharge device includes a lock hopper, a slag pool, and a slag remover. The slag pool is connected to the lock hopper, and the slag remover is used to remove the slag from the slag pool and transport it.

[0017] This application provides a biomass cascade gasification gasification device, comprising a primary gasification system and a secondary gasification system. The primary gasification system uses superheated steam and oxygen as gasifying agents. This technology offers strong raw material adaptability, allowing for the use of biomass briquettes or regular bulk biomass, resulting in low raw material pretreatment costs. A fluidization device ensures a uniform temperature field in the primary gasifier, reducing the likelihood of coking. A return feeder returns semi-coke particles separated by the cyclone separator to the primary gasifier, enabling them to participate in the gasification reaction again, thus improving the utilization rate of biomass raw materials and reducing semi-coke ash emissions. Based on this, the primary gasification system can reduce raw material pretreatment costs, improve biomass gasification stability, and reduce semi-coke ash emissions. The secondary gasification system introduces pure oxygen and uses non-catalytic oxidation technology to remove impurities such as semi-coke, tar, methane, unsaturated hydrocarbons, and organic sulfur from the crude syngas through high-temperature cracking. A quenching device cools the high-temperature crude syngas, effectively reducing dust and ash accumulation, preventing blockages in subsequent pipelines and equipment, and facilitating subsequent waste heat recovery. Based on this, the secondary gasification system can reduce the impurity content in the crude syngas, reduce the subsequent purification cost of the crude syngas, and improve operational stability. Attached Figure Description

[0018] To more clearly illustrate the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A structural diagram of a biomass cascade gasification and gasification device provided in this application embodiment;

[0020] Figure 2 A structural diagram of a two-stage gasification system provided in an embodiment of this application;

[0021] Figure 3 A structural diagram of a two-stage gasification system and a waste heat recovery and dust removal system provided in the embodiments of this application;

[0022] Figure 4 A structural diagram of a radiation waste cooker provided in an embodiment of this application;

[0023] Figure 5 This is a top view of a radiation waste cooker provided in an embodiment of this application.

[0024] The attached diagram is labeled as follows: 1-Primary gasifier, 2-Feeding device, 3-Cyclone separator, 4-Return feeder, 5-Secondary gasifier, 6-Gasifying agent injection device, 7-Quick cooling device, 701-Quick cooling chamber, 702-Quick cooling spray gun, 8-Radiant waste boiler, 801-Boiler drum, 802-First channel, 803-Second channel, 804-Screen-type superheater, 9-Evaporator, 10-Dust collector, 11-Economizer, 12-Slag discharge device. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this application.

[0026] I. Raw material pretreatment technology and cost.

[0027] Entrained flow gasification technology typically uses powdered or slurry feedstocks. Biomass generally contains large amounts of cellulose and lignin, making direct powdering and slurry formation difficult. Physical / chemical pretreatment of the biomass feedstock is necessary to convert it into a form suitable for powdering or slurry formation. Regardless of the pretreatment technology used, there will always be some loss of effective energy, increasing raw material costs. It is estimated that the feedstock cost for biomass entrained flow gasification is 600-700 yuan / ton of biomass. Based on the calculation of producing one ton of green methanol from 3.6 tons of biomass (fuel costs are calculated based on the feedstock equivalent), the feedstock + fuel cost for one ton of green methanol is approximately 2160-2520 yuan.

[0028] Fixed-bed technology requires high-density feedstock to ensure the stability of the gasification bed. High-density biomass feedstock processing technology has high energy consumption. It is estimated that the feedstock cost for fixed-bed biomass gasification is 500-600 yuan / ton. Based on the calculation that 3.7 tons of biomass (fuel costs are calculated based on feedstock conversion) produces one ton of green methanol, the feedstock + fuel cost for one ton of green methanol is approximately 1850-2220 yuan.

[0029] Fluidized bed technology has relatively low requirements for biomass feedstock; conventional briquetting is sufficient. Calculations show that the feedstock cost for biomass fluidized bed gasification is 350-400 yuan / ton of biomass. Based on the calculation that 4.4 tons of biomass (fuel costs are calculated based on the feedstock) produces one ton of green methanol, the feedstock and fuel cost for one ton of green methanol is approximately 1640-1845 yuan.

[0030] In summary, fluidized bed technology has the lowest raw material and fuel costs, followed by fixed bed, and airflow bed has the highest.

[0031] II. Content and composition of export impurities.

[0032] The fluidized bed technology has a high gasification temperature and few impurities. The gasification outlet is basically free of impurities such as methane, tar, unsaturated hydrocarbons, and organic sulfur, and the subsequent purification and impurity removal costs are very low.

[0033] Fixed-bed gasification technology suffers from low gasification temperatures and a significant temperature gradient in the gasifier, resulting in a gasification outlet containing large amounts of impurities such as methane, tar, unsaturated hydrocarbons, and organic sulfur compounds, leading to high subsequent purification and removal costs. It is estimated that the subsequent purification cost for biomass fixed-bed gasification is 150-200 yuan per ton of methanol.

[0034] Fluidized bed gasification technology has a low gasification temperature, but the temperature distribution within the gasifier is uniform. The gasification outlet contains a certain amount of impurities such as methane, tar, unsaturated hydrocarbons, and organic sulfur, resulting in high subsequent purification and removal costs. It is estimated that the subsequent purification cost for biomass fluidized bed gasification is 120-170 yuan / ton of methanol.

[0035] In summary, airflow bed technology has the lowest subsequent purification and impurity removal costs, followed by fluidized bed technology, and fixed bed technology has the highest costs.

[0036] In the biomass gasification to green methanol industry, the cost of biomass feedstock and fuel is the most economically sensitive factor for green methanol technology. Currently, the cost of feedstock, fuel, and purification for entrained flow technology is approximately RMB 2160-2520 per ton of green methanol; for fixed flow technology, it is approximately RMB 2000-2400 per ton; and for fluidized bed technology, it is approximately RMB 1760-2015 per ton. In the long run, gasification technologies with low feedstock requirements and high adaptability, combined with efficient impurity removal technologies, represent the future direction of the industry.

[0037] The core of this application is to provide a biomass cascade gasification gasification device for reducing the cost of raw material pretreatment and the impurity content in crude syngas.

[0038] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] Figure 1 This is a structural diagram of a biomass cascade gasification gasification device provided in an embodiment of this application. Figure 2 A structural diagram of a two-stage gasification system provided in this application embodiment is shown below. Figure 1 and Figure 2 As shown, the biomass cascade gasification unit includes a primary gasification system and a secondary gasification system. The primary gasification system includes a primary gasifier 1, a feeding device 2, a fluidizing device, a cyclone separator 3, and a return feeder 4. The feeding device 2 is connected to the primary gasifier 1 and is used to feed biomass feedstock into the primary gasifier 1. The fluidizing device is located at the bottom of the primary gasifier 1 and is used to feed pure oxygen and superheated steam into the primary gasifier 1. The inlet of the cyclone separator 3 is connected to the near top of the primary gasifier 1, and the outlet of the cyclone separator 3 is connected to the primary gasifier 1 via the return feeder 4. Near the bottom of the primary gasifier 1, a cyclone separator 3 is connected to separate semi-coke particles from the crude syngas generated by the gasification reaction of the primary gasifier 1. A return feeder 4 is used to return the semi-coke particles to the primary gasifier 1. The secondary gasification system includes a secondary gasifier 5, a gasifying agent injection device 6, and a quench device 7. The secondary gasifier 5 is connected to the cyclone separator 3. The gasifying agent injection device 6 is located at the top of the secondary gasifier 5 and is used to inject pure oxygen into the secondary gasifier 5. The quench device 7 is located at the bottom of the secondary gasifier 5 and is used to remove dust and cool the crude syngas.

[0040] The primary gasifier 1 can adopt a variable-diameter cylinder with a larger top and a smaller bottom, and the vertical angle of the variable diameter section (the angle between the side of the variable diameter section and the vertical direction) should not exceed 30°. The furnace wall of the primary gasifier 1, from the inside out, consists of refractory and wear-resistant castable, lightweight insulation material, and thermal insulation material. The function of the refractory and wear-resistant castable: The internal temperature of the gasifier is extremely high; the refractory and wear-resistant castable can withstand the high-temperature environment and prevent the furnace wall from being eroded by high temperatures. During the gasification process, solid particles inside the furnace (such as coal powder, ash, etc.) will cause severe abrasion to the furnace wall; the refractory and wear-resistant castable has good wear resistance and can effectively resist this abrasion, extending the service life of the furnace wall. The function of the lightweight insulation material: Lightweight insulation material has a low thermal conductivity, which can effectively prevent heat transfer from the inside of the furnace to the outside, reduce heat loss, and improve the thermal efficiency of the gasifier. Compared with traditional heavy insulation materials, lightweight insulation material has a lower density, which can reduce the overall weight of the furnace wall without reducing insulation performance, facilitating the installation and support of the furnace body. The role of thermal insulation material: Thermal insulation material is the last line of defense for the furnace wall, which can further reduce heat loss, ensure that the temperature of the outer surface of the furnace wall is within a safe range, and prevent personnel burns and equipment overheating; by reducing heat loss, the energy consumption of the gasifier can be reduced and the energy utilization efficiency can be improved.

[0041] The fluidization unit is used to input pure oxygen and superheated steam into the primary gasifier 1. The pure oxygen provides sufficient oxygen for the gasification reaction, ensuring its full progress in the oxidation stage. The superheated steam participates in a series of chemical reactions during gasification, contributing to improved syngas quality and yield. The fluidization unit keeps the biomass pellets in a fluidized state, ensuring full contact between the biomass feedstock and the gasifying agent (pure oxygen and superheated steam), thus improving gasification efficiency. The fluidization unit is located at the bottom of the primary gasifier 1 and connected to the furnace body via a flange for easy disassembly and maintenance. The fluidization unit includes a feed cylinder, a central fluidizer, branch fluidizing pipes, and branch fluidizers. The feed cylinder is connected to the bottom of the primary gasifier 1. The central fluidizer is located at the top neck of the feed cylinder. Multiple branch fluidizing pipes are arranged on the side wall near the top of the feed cylinder, and each branch fluidizing pipe is equipped with a branch fluidizer. The feed cylinder has 6-12 branch fluidizing tubes arranged on its upper sidewall. Each branch fluidizing tube has 3 branch fluidizers evenly distributed, and the diameter of the central fluidizer is approximately twice that of the branch fluidizers. The feed cylinder serves as the channel for the gasifying agent (pure oxygen and superheated steam) to enter the primary gasifier 1. The main function of the central fluidizer is to ensure that the gasifying agent entering the primary gasifier 1 is evenly distributed, forming a good fluidization state, and promoting full contact and reaction between the biomass feedstock and the gasifying agent. The relatively large diameter of the central fluidizer, approximately twice that of the branch fluidizers, allows it to form a strong fluidization effect in the central area of ​​the feed cylinder, providing a good fluidization environment for the gasification reaction of the biomass feedstock. The function of the branch fluidizing pipe and the branch fluidizer is to further distribute and disperse the gasifying agent in the feed cylinder, so that the gasifying agent can enter the primary gasifier 1 more evenly, and enhance the fluidization effect of the biomass feedstock in the furnace. The branch fluidizer is relatively small and can penetrate into different positions in the feed cylinder, so that the gasifying agent forms multiple fluidization points in the feed cylinder, thereby improving the fluidization quality of the biomass feedstock in the entire feed cylinder and ensuring the uniformity and efficiency of the gasification reaction.

[0042] The feeding device 2 is connected to the primary gasifier 1 and is used to transport biomass raw materials into the primary gasifier 1. This application embodiment does not specify the number of feeding devices 2; they can be configured according to actual conditions. The feeding device 2 includes a hopper, a discharge pipe, an anti-blocking device, and a screw feeder. The hopper is located above the screw feeder. One end of the discharge pipe is connected to the bottom of the hopper, and the other end is connected to the first end of the screw feeder. The second end of the screw feeder is connected to the primary gasifier 1. The anti-blocking device ensures continuous material entry into the screw feeder. The hopper is the starting part of the feeding device 2 and is used to store the biomass raw materials to be processed. It is located above the screw feeder and provides raw material reserves for subsequent conveying processes. The discharge pipe connects the bottom of the hopper and the first end of the screw feeder, serving as the channel for conveying biomass raw materials from the hopper to the screw feeder. The anti-blocking device can be an air purge pipe, etc. Its function is to supply air to the screw feeder, preventing blockage of biomass feedstock within the feeder and ensuring smooth feedstock delivery. The anti-blocking device also effectively prevents backflow of high-temperature gas within the primary gasifier 1. The screw feeder uses the rotation of its helical blades to sequentially transport biomass feedstock from the hopper to the primary gasifier 1.

[0043] The inlet of the cyclone separator 3 is connected to the near-top of the primary gasifier 1, and the outlet is connected to the near-bottom of the primary gasifier 1 via a return feeder 4. The crude syngas generated by the gasification reaction in the primary gasifier 1 contains semi-coke particles, which the cyclone separator 3 can separate using centrifugal force. The return feeder 4 then returns the separated semi-coke particles to the near-bottom of the primary gasifier 1, allowing them to participate in the gasification reaction again. This improves the utilization rate of biomass feedstock while reducing semi-coke emissions. The return feeder 4 can be a chute-type return feeder 4.

[0044] The feedstock in the secondary gasifier 5 is the outlet gas from the primary gasification system, which contains impurities such as methane, tar, semi-coke, unsaturated hydrocarbons, and organic sulfur. The secondary gasifier 5 can be cylindrical with a constant diameter.

[0045] The gasifying agent injection device 6 is located at the top of the secondary gasifier 5 and is used to inject pure oxygen into the secondary gasifier 5. It adopts a combination of central oxygen and epoxy to improve the mixing effect of oxygen and raw material gas.

[0046] A quenching device 7 is located at the bottom of the secondary gasifier 5 and is used to remove dust and cool the crude syngas. The quenching device 7 employs an adiabatic humidification dry quenching method to cool and humidify the gas exiting the gasifier in stages, causing the molten slag to cool and solidify, while simultaneously removing large particles of dust and ash agglomerates. The outlet gas temperature of the quenching device 7 is 850℃-950℃ and enters the subsequent waste heat recovery and dust removal system; the solidified molten slag, large particles of dust, and ash agglomerates enter the slag discharge device 12. The quenching device 7 includes a quenching chamber 701, quenching pipes, quenching spray guns 702, circulating water cooling pipes, and slag flushing water nozzles. The top of the quenching chamber 701 is connected to the bottom of the secondary gasifier 5. Multiple quenching spray guns 702 are distributed circumferentially along the top of the quenching chamber 701. The quenching pipes are connected to the quenching spray guns 702, and the circulating water cooling pipes and slag flushing water nozzles are located at the bottom of the quenching chamber 701. The quenching spray gun 702 can be either a quenching water spray gun or a dry gas quenching spray gun. The quenching water spray gun has a high-efficiency atomization function to ensure the dry quenching effect. The quenching medium can be dry syngas or demineralized water. The lower part of the quenching chamber 701 is equipped with a circulating water cooling pipe and a slag flushing water nozzle to prevent slag buildup and blockage at the slag outlet.

[0047] This application provides a biomass cascade gasification gasification device, comprising a primary gasification system and a secondary gasification system. The primary gasification system uses superheated steam and oxygen as gasifying agents. This technology has strong raw material adaptability, allowing the use of biomass briquettes or regular bulk biomass, resulting in low raw material pretreatment costs. A fluidizing device ensures a uniform temperature field in the primary gasifier 1, reducing the likelihood of coking. A return feeder 4 returns the semi-coke particles separated by the cyclone separator 3 to the primary gasifier 1, allowing them to participate in the gasification reaction again, improving the utilization rate of biomass raw materials and reducing semi-coke ash emissions. Based on this, the primary gasification system can reduce raw material pretreatment costs, improve biomass gasification stability, and reduce semi-coke ash emissions. The secondary gasification system introduces pure oxygen and uses non-catalytic oxidation technology to remove impurities such as semi-coke, tar, methane, unsaturated hydrocarbons, and organic sulfur carried in the crude syngas through high-temperature cracking. A quenching device 7 cools the high-temperature crude syngas, effectively reducing dust and ash accumulation, preventing blockages in subsequent pipelines and equipment, and facilitating subsequent waste heat recovery. Based on this, the secondary gasification system can reduce the impurity content in the crude syngas, reduce the subsequent purification cost of the crude syngas, and improve operational stability.

[0048] Based on the above embodiments, Figure 3 A structural diagram of a two-stage gasification system and a waste heat recovery and dust removal system provided in the embodiments of this application is shown below. Figure 3As shown, the system also includes a waste heat recovery and dust removal system. This system comprises a radiant waste boiler 8, an evaporator 9, a dust collector 10, and an economizer 11 connected in sequence. The inlet of the radiant waste boiler 8 is connected to the outlet of the quench chamber 701 of the quenching device 7, and the outlet of the dust collector 10 is connected to the inlet of the economizer 11. The syngas temperature entering the radiant waste boiler 8 is 850-950℃, the syngas temperature entering the dust collector 10 is 350-450℃, and the syngas temperature exiting the economizer 11 is 200-230℃. The waste heat recovery and dust removal system employs a cascaded waste heat recovery and dust removal method, effectively improving the sensible heat utilization efficiency of the crude syngas while avoiding heat exchanger blockage.

[0049] Figure 4 This is a structural diagram of a radiation waste cooker provided in an embodiment of this application. Figure 5 A top view of a radiation waste cooker provided in an embodiment of this application, as shown below. Figure 4 and Figure 5 As shown, the radiant waste boiler 8 includes a boiler drum 801, a first channel 802, a second channel 803, and a screen-type superheater 804. Both the first channel 802 and the second channel 803 are constructed using a molded wall. The second channel 803 is located between the first channel 802 and the screen-type superheater 804. The bottom of the first channel 802 and the bottom of the second channel 803 are connected. The top of the first channel 802 is connected to the top of the screen-type superheater 804. The screen-type superheater 804 includes a screen-type superheating zone and a convection evaporation zone. The screen-type superheating zone is located above the convection evaporation zone. The boiler drum 801 is connected to the top of the first channel 802, the top of the first channel 802, the screen-type superheating zone, and the convection evaporation zone. The screen-type superheater 804 is connected to the evaporator 9. Figure 4 As shown, saturated steam in boiler drum 801 flows into the screen-type superheated zone, saturated steam in the convection evaporation zone flows into boiler drum 801, and superheated steam in the screen-type superheated zone enters the subsequent evaporator 9. The first channel 802 is the first cooling zone after the high-temperature crude syngas enters the radiant waste boiler 8; it adopts a membrane wall structure, which can effectively absorb the heat of the high-temperature gas. The second channel 803, located between the first channel 802 and the screen-type superheater 804, also adopts a membrane wall structure, further cooling the crude syngas and continuing to recover heat. The screen-type superheater 804 includes a screen-type superheated zone and a convection evaporation zone. The screen-type superheated zone is located above the convection evaporation zone, and its function is to superheat the saturated steam from boiler drum 801, improving the steam temperature and quality. The screen-type superheater 804 heats the steam to the required superheated temperature by absorbing the waste heat of the crude syngas. The screen-type superheater 804 is connected to the evaporator 9, transporting the superheated steam to the subsequent evaporator 9. The temperature of the syngas entering the screen-type superheater 804 is below 650℃, and the temperature of the syngas exiting the economizer 11 is 200-230℃. The economizer 11 is connected to the outlet of the dust collector 10.

[0050] Based on the above embodiments, the bottom of the fluidization device, the bottom of the quenching device 7, and the bottom of the radiant waste boiler 8 are all equipped with slag discharge devices 12. The slag discharge device 12 at the bottom of the fluidization device is used to discharge the bottom slag generated in the primary gasifier 1 during the gasification process. This bottom slag mainly consists of non-gasifiable parts of the biomass raw materials, such as minerals and ash. Through the slag discharge device 12, this bottom slag can be discharged from the system periodically or continuously to prevent the bottom slag from accumulating in the fluidization device and affecting the normal progress of the gasification reaction and the fluidization effect. The slag discharge device 12 located at the bottom of the quenching device 7 is used to discharge larger solid impurities that settle down in the quenching device 7 during the quenching process. During the quenching process, the crude syngas is rapidly cooled, and some solid particles (such as semi-coke fragments and ash) settle to the bottom of the quenching device 7. The slag discharge device 12 can discharge these solid impurities in a timely manner to ensure the normal operation of the quenching device 7 and the cleanliness of the subsequent system. The slag discharge device 12 located at the bottom of the radiant waste boiler 8 is used to discharge the solid particles that settle in the radiant waste boiler 8 during the waste heat recovery process. After the radiant waste boiler 8 is cooled and heat exchanged, some solid particles in the crude syngas will settle at the bottom of the waste boiler due to the decrease in temperature. The function of the slag discharge device 12 is to discharge these particles to prevent them from accumulating in the waste boiler and affecting the heat exchange efficiency and operational stability of the waste boiler.

[0051] This application does not specifically limit the slag discharge device 12. One embodiment includes a slag discharge chute, a screw conveyor, a slag cooler, and an auxiliary cooling device. The slag discharge chute is connected to the screw conveyor, the slag cooler cools the ash and slag within the screw conveyor, and the auxiliary cooling device provides a cooling medium to the slag cooler. If the slag cooler uses water cooling, the auxiliary cooling system includes a circulating water pump, a cooling tower, and a water treatment device; if the slag cooler uses air cooling, the auxiliary cooling system includes a blower and air ducts. The slag discharge chute can be made of carbon steel with a wear-resistant coating to ensure service life, and the chute has a circular arc slope with an angle of approximately 45° to the horizontal. Another embodiment includes a slag discharge device 12 including a lock hopper, a slag pool, and a slag remover. The slag pool is connected to the lock hopper, and the slag remover removes and transports the slag from the slag pool. The slag discharge device 12 can also consist only of a slag pool and a slag remover system, suitable for primary and secondary gasification systems operating at atmospheric or slightly positive pressure.

[0052] To better understand this application, the gasification process of the biomass cascade gasification gasification device is described below.

[0053] Primary gasification system: Biomass briquettes or flakes are fed into the primary gasifier 1 through the feeding device 2. Pure oxygen and steam enter the primary gasifier 1 through the fluidization device at the bottom of the primary gasifier 1. The biomass raw materials, pure oxygen, and steam undergo a gasification reaction in the primary gasifier 1. The generated crude syngas and unreacted biomass semi-coke particles enter the cyclone separator 3 for separation. The separated semi-coke is returned to the primary gasifier 1 through the return feeder 4. The remaining semi-coke enters the secondary gasifier 5 of the secondary gasification system along with the crude syngas. The ash and slag enter the slag discharge device 12 at the bottom of the fluidization device.

[0054] Secondary gasification system: The crude syngas and its accompanying semi-coke from the outlet of cyclone separator 3 enter the upper part of the secondary gasifier 5. Pure oxygen, the gasifying agent, enters the secondary gasifier 5 through the gasifying agent injection device 6. The crude syngas and its accompanying semi-coke undergo a gasification reaction with the pure oxygen in the secondary gasifier 5. The resulting crude syngas enters the quenching device 7. The quenched crude syngas then enters the subsequent waste heat recovery and dust removal system, while the ash and slag enter the slag discharge device 12 at the bottom of the quenching device 7.

[0055] Waste heat recovery and dust removal system: The crude syngas from the outlet of the secondary gasifier 5 enters the radiant waste boiler 8. The crude syngas and boiler feedwater exchange heat in the radiant waste boiler 8 to produce superheated or saturated steam as a byproduct. The crude syngas from the outlet of the radiant waste boiler 8 enters the dust collector 10. The crude syngas from the outlet of the dust collector 10 enters the economizer 11. The crude syngas and boiler feedwater exchange heat in the economizer 11 to increase the boiler feedwater temperature. The crude syngas exiting the economizer 11 enters the subsequent purification process.

[0056] The key technology of biomass cascade gasification provided in this application is the use of cascade gasification technology, namely a gasification technology combining a primary gasification system and a secondary gasification system. The secondary gasification system employs high-temperature gasification with pure oxygen to thoroughly remove methane, tar, organic sulfur, unsaturated hydrocarbons, etc., from the crude syngas; the secondary gasification system also utilizes dry quenching technology. The waste heat recovery and dust removal system consists of a waste heat boiler connected to a dust removal device, which in turn is connected to an economizer.

[0057] The biomass cascade gasification technology employs a cascade gasification system. Through a simple, low-cost primary gasification system with minimal pretreatment of raw materials and a highly efficient secondary gasification system for impurity removal, it effectively addresses the trade-offs between the difficulty and cost of biomass pretreatment and the complexity of impurities and components in the crude syngas. Specifically, it avoids the pitfalls of high raw material costs resulting in low impurity content in crude syngas versus low raw material costs resulting in high and complex impurities in crude syngas. This improves the overall techno-economic efficiency of biomass gasification technology. The secondary gasification system utilizes dry quenching technology, effectively resolving the blockage issues at the biomass liquid slag discharge port and subsequent radiant waste boiler. The waste heat recovery and dust removal system employs a cascaded waste heat recovery method. First, waste heat is used to generate steam, then dust is removed, and finally, the waste heat is used to heat the boiler feedwater, achieving the final waste heat recovery. The dust removal device is positioned between the waste boiler and the economizer, effectively solving the problem of ash blockage in the heat exchanger at medium and low temperatures.

[0058] The above provides a detailed description of a biomass cascade gasification apparatus provided in this application. The various embodiments in the specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. It should be noted that those skilled in the art can make various improvements and modifications to this application without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this application.

[0059] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A biomass cascade gasification gasification device, characterized in that, include: Primary gasification system and secondary gasification system; The primary gasification system includes a primary gasifier (1), a feeding device (2), a fluidizing device, a cyclone separator (3), and a return feeder (4). The feeding device (2) is connected to the primary gasifier (1) and is used to feed biomass raw materials into the primary gasifier (1). The fluidizing device is located at the bottom of the primary gasifier (1) and is used to feed pure oxygen and superheated steam into the primary gasifier (1). The inlet of the cyclone separator (3) is connected to the near top of the primary gasifier (1), and the outlet of the cyclone separator (3) is connected to the near bottom of the primary gasifier (1) through the return feeder (4). The separator (3) is used to separate the semi-coke particles in the crude syngas generated by the gasification reaction of the primary gasifier (1). The return feeder (4) is used to return the semi-coke particles to the primary gasifier (1). The secondary gasification system includes a secondary gasifier (5), a gasifying agent injection device (6), and a quenching device (7). The secondary gasifier (5) is connected to the cyclone separator (3). The gasifying agent injection device (6) is located at the top of the secondary gasifier (5) and is used to inject pure oxygen into the secondary gasifier (5). The quenching device (7) is located at the bottom of the secondary gasifier (5) and is used to remove dust and cool the crude syngas.

2. The biomass cascade gasification and gasification device according to claim 1, characterized in that, The feeding device (2) includes a hopper, a discharge pipe, an anti-blocking device and a screw feeder. The hopper is located above the screw feeder. One end of the discharge pipe is connected to the bottom of the hopper, and the other end of the discharge pipe is connected to the first end of the screw feeder. The second end of the screw feeder is connected to the primary gasifier (1). The anti-blocking device is used to ensure that the material continuously enters the screw feeder.

3. The biomass cascade gasification and gasification device according to claim 1, characterized in that, The fluidization device includes a feed cylinder, a central fluidizer, branch fluidizing pipes and branch pipe fluidizers. The feed cylinder is connected to the bottom of the primary gasifier (1). The central fluidizer is located at the top neck of the feed cylinder. Multiple branch fluidizing pipes are arranged on the side wall near the top of the feed cylinder, and each branch fluidizing pipe is equipped with a branch pipe fluidizer.

4. The biomass cascade gasification gasification device according to claim 1, characterized in that, The furnace wall of the primary gasifier (1) consists of refractory and wear-resistant castable, lightweight insulation material and thermal insulation material from the inside to the outside.

5. The biomass cascade gasification gasification device according to claim 1, characterized in that, The quenching device (7) includes a quenching chamber (701), a quenching pipe, a quenching spray gun (702), a circulating water cooling pipe, and a slag flushing water nozzle. The top of the quenching chamber (701) is connected to the bottom of the secondary gasifier (5). Multiple quenching spray guns (702) are distributed circumferentially along the top of the quenching chamber (701). The quenching pipe is connected to the quenching spray gun (702). The circulating water cooling pipe and the slag flushing water nozzle are located at the bottom of the quenching chamber (701).

6. The biomass cascade gasification gasification device according to claim 1, characterized in that, It also includes a waste heat recovery and dust removal system, which includes a radiant waste boiler (8), an evaporator (9), a dust collector (10) and an economizer (11) connected in sequence. The inlet of the radiant waste boiler (8) is connected to the outlet of the quench chamber (701) of the quench device (7).

7. The biomass cascade gasification gasification device according to claim 6, characterized in that, The radiant waste boiler (8) includes a boiler drum (801), a first channel (802), a second channel (803), and a screen-type superheater (804). The first channel (802) and the second channel (803) are both made of molded walls. The second channel (803) is located between the first channel (802) and the screen-type superheater (804). The bottom of the first channel (802) and the bottom of the second channel (803) are connected. The top of the first channel (802) is connected to the top of the screen-type superheater (804). The screen-type superheater (804) includes a screen-type superheating zone and a convection evaporation zone. The screen-type superheating zone is located above the convection evaporation zone. The boiler drum (801) is connected to the top of the first channel (802), the top of the first channel (802), the screen-type superheating zone, and the convection evaporation zone, respectively. The screen-type superheater (804) is connected to the evaporator (9).

8. The biomass cascade gasification gasification device according to claim 6, characterized in that, The bottom of the fluidizing device, the bottom of the quenching device (7), and the bottom of the radiant waste pot (8) are all provided with slag discharge devices (12).

9. The biomass cascade gasification gasification device according to claim 8, characterized in that, The slag discharge device (12) includes a slag discharge chute, a screw conveyor, a slag cooler, and an auxiliary cooling device. The slag discharge chute is connected to the screw conveyor. The slag cooler is used to cool the ash and slag in the screw conveyor. The auxiliary cooling device is used to provide a cooling medium for the slag cooler.

10. The biomass cascade gasification and gasification device according to claim 8, characterized in that, The slag discharge device (12) includes a lock hopper, a slag pool, and a slag remover. The slag pool is connected to the lock hopper, and the slag remover is used to remove the slag from the slag pool and transport it.

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