Fluidized bed gasification system

Abstract

The utility model relates to a fluidized bed gasification system. The fluidized bed gasification system comprises a conveying tank, a conveying pipeline, a gasification furnace and a control assembly, the conveying tank is provided with an ash outlet, the gasification furnace is provided with an ash return opening, and the ash outlet and the ash return opening are connected through the conveying pipeline; the conveying tank is used for conveying fly ash to the gasification furnace; an accelerator and a control valve are arranged on the conveying pipeline; the accelerator is sequentially and coaxially provided with a pressure-bearing pipeline layer, a ventilation layer and a supporting framework layer from outside to inside, and the pressure-bearing pipeline layer is connected with a gas conveying pipeline. A stop valve is arranged on the gas pipeline; and the control valve is arranged at the downstream of the accelerator. According to the circulating control system of the fluidized bed gasifier, gas and solid phases are fully mixed by utilizing the accelerator, and then parameters such as downstream speed, density and the like are measured, so that the flow of powder returning gas is greatly reduced, gasification reaction is facilitated, and the conversion rate of gasified carbon is greatly improved.

Description

Technical Field

[0001] The utility model relates to a fluidized bed gasification system. Background Art

[0002] Fluidized bed gasifiers use dry dust removal (filters or cyclones) to capture fly ash, transport it to an ash silo, and then discharge it locally through spiral humidification. Because the fly ash produced by the gasifier has a carbon content of approximately 50% and is relatively fine (average particle size around 10 μm), the humidification process with a humidifier generates significant dust. If shipped in sealed tank trucks, the dust is even greater during unloading, impacting the on-site environment. Fly ash produced by the gasifier accounts for approximately 30% of the raw material. If this fly ash is not effectively utilized, the carbon conversion rate of the fluidized bed gasifier is significantly reduced.

[0003] There are two main forms of fly ash utilization: combustion and gasification. Combustion uses fly ash produced after the gasification process, which is primarily composed of incompletely converted fixed carbon and has a finer particle size and a higher ignition point, resulting in a lower overall fly ash utilization rate.

[0004] The gasification form currently uses a spiral weighing feeder for transportation, but the sealing ring in the middle of the spiral weighing feeder is made of rubber, which cannot meet the requirements of high temperature and high pressure. The technology is also immature, and there are unstable operations and safety hazards.

[0005] These problems reduce the efficiency and safety of fluidized bed gasifiers and urgently need to be improved. Utility Model Content

[0006] The technical problem to be solved by the utility model is to overcome the defect of low carbon conversion efficiency of the fluidized bed gasifier in the prior art and provide a fluidized bed gasification system.

[0007] The utility model solves the above technical problems through the following technical solutions:

[0008] In a first aspect, the present invention provides a fluidized bed gasification system, which includes a delivery tank, a delivery pipeline, a gasifier, and a control assembly;

[0009] The conveying tank is provided with an ash outlet, and the gasifier is provided with an ash return outlet, and the ash outlet and the ash return outlet are connected through the conveying pipeline; the conveying tank is used to convey fly ash to the gasifier;

[0010] The delivery pipeline is provided with an accelerator and a control valve; the accelerator is coaxially provided with a pressure-bearing pipeline layer, a ventilation layer, and a support frame layer from the outside to the inside, with a gap between the pressure-bearing pipeline layer and the ventilation layer, and the pressure-bearing pipeline layer is connected to a gas pipeline; the gas pipeline is provided with a shut-off valve; the control valve is located downstream of the accelerator;

[0011] The control assembly is electrically connected to the shut-off valve and the control valve, and is used to adjust the mass of the fly ash delivered to the gasifier.

[0012] In the present invention, the “downstream” means that, with the flow direction of the fly ash as the positive direction, the control valve is located downstream of the accelerator in the flow direction of the fly ash.

[0013] In the present invention, the delivery pipeline may also be provided with at least one of a speed meter, a density meter, a pressure meter and a thermometer, and the speed meter, the density meter, the pressure meter and the thermometer are all electrically connected to the control assembly.

[0014] The speed meter and the densitometer may be used to detect mass information of the fly ash transported into the gasifier within a preset time.

[0015] The accelerator and the controller may be used to adjust the mass of the fly ash delivered to the gasifier within the preset time.

[0016] The pressure gauge can be used to detect the pressure in the delivery pipeline.

[0017] Wherein, the thermometer can be used to detect the temperature in the conveying pipeline.

[0018] In the present invention, the fluid channel of the accelerator may be perpendicular to the ground.

[0019] In the present invention, the material of the pressure-bearing pipe layer can be metal.

[0020] In the present invention, the material of the ventilation layer can be metal or ceramic.

[0021] In the utility model, the ventilation layer can be provided with a plurality of ventilation holes.

[0022] The diameter of the ventilation holes may be 0.1-2.0 μm, for example, 0.2-0.5 μm.

[0023] In the present invention, the material of the supporting skeleton layer can be metal.

[0024] In the present invention, the supporting skeleton layer can be bonded to the ventilation layer.

[0025] In the present invention, the structure of the supporting skeleton layer can be a mesh hollow structure.

[0026] In the present invention, an inflation cone may be further provided between the ash outlet and the conveying pipe to fluidize the fly ash.

[0027] Wherein, the inflation cone and the ash outlet can be flange-connected.

[0028] In the present invention, a first shut-off valve may be further provided on the conveying pipeline. The first shut-off valve is located between the ash outlet and the accelerator and is used to control the on-off of the conveying pipeline.

[0029] In the present invention, the ash return port can also be connected to an air outlet pipe, and the air outlet pipe is provided with an ash return protection valve for controlling the on-off of the air outlet pipe.

[0030] In the present invention, the fluidized bed gasification system may further include an ash bin for storing fly ash; the ash bin is provided with an ash inlet, and the conveying pipeline is further provided with a bifurcation; the ash inlet and the bifurcation are connected via a conveying sub-pipeline.

[0031] Wherein, the conveying sub-pipeline may be provided with a switching valve for connecting the conveying pipeline and the conveying sub-pipeline when the gasification furnace reaches a preset ash return stop condition, so that the fly ash enters the ash storage.

[0032] The conveying pipeline may further be provided with a second shut-off valve, which is provided between the bifurcation and the ash return port and is used to control the on-off of the conveying pipeline.

[0033] The transport sub-pipeline can also be connected to an external air pipe, and the external air pipe is provided with an ash storage protection valve for controlling the on-off of the external air pipe.

[0034] In the present invention, the conveying tank may be further provided with an ash supply port, and the gasification furnace may be further provided with an ash discharge port, the ash supply port and the ash discharge port being connected via a circulation pipeline, and the circulation pipeline may be provided with a cooling device and a dust removal device.

[0035] In a second aspect, the present invention provides a fluidized bed gasification control method, which is implemented by the fluidized bed gasification furnace system as described above, comprising the following steps:

[0036] The control valve and / or the shut-off valve are controlled by the control assembly to adjust the fly ash transported to the ash return port.

[0037] In the present invention, when a velocity meter, a density meter, a pressure meter and a thermometer are further provided on the conveying pipeline, the specific steps of regulating the fly ash conveyed to the ash return port may include:

[0038] The control component detects quality information of the fly ash delivered to the gasifier within a preset time, and adjusts the quality of the fly ash delivered to the gasifier within the preset time according to the quality information and preset control conditions.

[0039] In the present invention, when the fluidized bed gasification system further includes a first shut-off valve, a second shut-off valve, and an ash return protection valve, the specific steps of regulating the fly ash transported to the ash return port may include:

[0040] Close the first shut-off valve and the second shut-off valve, and open the dust return protection valve;

[0041] Opening the control valve to introduce gas into the delivery pipeline through the accelerator;

[0042] When the pressure detected by the pressure gauge is higher than the pressure in the gasifier, the second shut-off valve is opened, and then the ash return protection valve is closed;

[0043] When the pressure detected by the pressure gauge is continuously higher than the pressure in the gasifier, the first shut-off valve is opened to control the conveying tank to convey fly ash into the conveying pipeline.

[0044] The specific steps of regulating the fly ash transported to the ash return port further include:

[0045] When the gasifier is in an abnormal state, the second shut-off valve is closed and the ash return protection valve is opened.

[0046] Wherein, when the fluidized bed gasification furnace circulation control system further includes a switching valve, the specific step of adjusting the fly ash transported to the ash return port further includes:

[0047] When the gasifier reaches a preset ash return stop condition, the second shut-off valve is closed and the switching valve is opened to allow the fly ash to enter the ash bin.

[0048] Without violating the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain preferred embodiments of the present utility model.

[0049] The positive progress effect of this utility model is:

[0050] (1) The fluidized bed gasification system of the present invention utilizes an accelerator to fully mix the gas and solid phases, and then through the measurement of downstream parameters such as velocity and density, it greatly reduces the return gas flow, which is beneficial to the gasification reaction. The carbon conversion rate can be increased from 75% to 98%, and the CO content of the raw coal gas can be significantly increased from 23vol% to 29vol%. The gas delivery volume can be increased from 250Nm 3 / h reduced to 49Nm 3 / h;

[0051] (2) In the fluidized bed gasification system of the present invention, fly ash is transported back to the gasifier for re-reaction, which reduces the discharge of fly ash. The operation of on-site fly ash loading and delivery is greatly reduced, which greatly improves the environmental sanitation of the production site and effectively prevents pneumoconiosis.

[0052] (3) The fluidized bed gasification system of the present invention has a three-layer accelerator structure, which allows for very sufficient contact between gas and solid, forming dense phase transport, low gas consumption, less inert gas entering the gasifier, less fly ash cooling, and is beneficial to fly ash conversion;

[0053] (4) The fluidized bed gasification control method of the present invention provides instantaneous feedback of the control program, timely and accurate adjustment of the gas volume and solid flow rate, achieving the purpose of precise control, stabilizing the return powder volume, and making the control more accurate. The accelerator's sufficient mixing method and the conveying control method set on the downstream pipeline jointly help the system operate efficiently. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 Schematic diagram of the structure of the fluidized bed gasification system in Example 1;

[0055] Figure 2 Detailed structural diagram of the distribution plate in Example 1;

[0056] Figure 3 Detailed structural diagram of the accelerator in Example 1;

[0057] Figure 4 Detailed structural diagram of the accelerator in Comparative Example 1;

[0058] The numbers in the figure are as follows: conveying tank 1, inflation cone 2, first shut-off valve 3, accelerator 4, shut-off valve 40, pressure pipe layer 41, ventilation layer 42, supporting skeleton layer 43, accelerator 4', rotary feeder 44', gas adding pipe 45', control valve 5, speedometer 6, densitometer 7, pressure gauge 8, thermometer 9, second shut-off valve 10, switching valve 11, ash return protection valve 12, distribution plate 13, gasification furnace 14, ash storage protection valve 15, ash storage 16, cooling device 17, dust removal device 18. DETAILED DESCRIPTION

[0059] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. In the following examples, the experimental methods without specific conditions are selected according to conventional methods and conditions, or according to the product specifications.

[0060] In the embodiments of the present invention, prefixes such as "first" and "second" are used only to distinguish different description objects and have no limiting effect on the position, order, priority, quantity or content of the described objects. In the embodiments of the present invention, the use of prefixes such as ordinal numbers to distinguish description objects does not constitute a limitation on the described objects. For the statement of the described objects, please refer to the description in the context of the claims or embodiments, and the use of such prefixes should not constitute an unnecessary limitation. In addition, in the description of this embodiment, unless otherwise specified, the meaning of "plurality" is two or more.

[0061] The main functions of the components that may be used in the following embodiments are described as follows:

[0062] Transport tank 1: It is a pressurized ash tank, which can be an ash tank at the bottom of the filter or a separate ash tank. The pressure of transport tank 1 must be higher than the pressure of gasifier 14 to prevent high-temperature materials in gasifier 14 from returning to the inside of the pipeline and causing fire, explosion and other accidents.

[0063] Aeration Cone 2: A conical sintered metal element, which allows gas but not ash, has a dense filter mesh welded to its center, allowing gas to pass but ash to remain. This component ensures thorough mixing of ash in conveying tank 1, achieving a fluidized state and breaking down ash bridging. This prevents ash accumulation and clogging at the bottom of the aeration cone, preventing blockage at the conveying starting point and ensuring optimal ash delivery.

[0064] The first shut-off valve 3: Its function is to cut off the logistics when the conditions for use are not met.

[0065] Accelerator 4: Use a small amount of gas to ensure that the fly ash and gas are in a fluidized state, making the solid particles fluid.

[0066] Control valve 5: Its function is to partially or completely cut off the logistics, or change the flow direction of the logistics.

[0067] Speedometer 6: measures the speed of conveying materials. When used in conjunction with density meter 7, it can calculate the mass of the material per unit time.

[0068] Density meter 7: measures the density of the conveyed material. When used in conjunction with the speed meter 6, it can calculate the mass of the material per unit time.

[0069] Pressure gauge 8: There can be three of them, located at different positions of the conveying pipeline, to monitor the pressure in the pipeline. The change in pressure can be used to determine whether the conveyed material is in a normal state.

[0070] Thermometer 9: Detects the temperature of the material to determine whether there is material passing through, or whether the material inside the pipeline is transported completely when the material stops being transported.

[0071] The second shut-off valve 10 is used in conjunction with the ash return protection valve 12 to prevent the high-temperature material in the gasification furnace 14 from leaking and causing fire or explosion.

[0072] Shut-off valve 11: When the gasifier 14 does not need to return materials, it switches to the ash storage 16 for temporary storage.

[0073] Ash return protection valve 12: prevents high-temperature materials in the gasification furnace 14 from leaking, causing fire or explosion.

[0074] Distribution plate 13: The interface where fly ash enters the gasifier 14.

[0075] Ash storage protection valve 15: a component used to ensure that the ash conveying pipeline is not blocked or to detect whether the pipeline is unobstructed.

[0076] Ash storage 16: Temporary storage for fly ash.

[0077] The above-selected components that come into contact with fly ash are all suitable for high temperature and high pressure.

[0078] Example 1

[0079] A fluidized bed gasification control system, such as Figure 1 , including a conveying tank 1, a gasifier 14 and a control component; the conveying tank 1 is connected to the ash return port of the gasifier 14 through a conveying pipeline, and the conveying tank 1 is used to convey fly ash to the gasifier 14, and the fly ash enters the gasifier 14 from the ash return port through the conveying pipeline; a control component is provided on the conveying pipeline, and the control component is used to detect the quality information of the fly ash conveyed to the gasifier 14 within a preset time; the control component is also used to adjust the quality of the fly ash conveyed to the gasifier 14 within a preset time according to the quality information and preset control conditions.

[0080] In this embodiment, fly ash from gasifier 14 first passes through cooling device 17 and is then captured by dust removal device 18 before entering transfer tank 1. The pressure within transfer tank 1 is higher than the pressure within gasifier 14, preventing high-temperature materials within gasifier 14 from returning to the pipeline and causing fires, explosions, and other accidents. In this embodiment, the source gasifier 14 generating the fly ash and the target gasifier 14 to which transfer tank 1 delivers the fly ash are the same gasifier 14. In other embodiments, they may be different gasifiers.

[0081] In this embodiment, a distribution plate 13 is provided at the bottom of the gasifier 14. The structure and connection relationship between the two are conventionally selected in the art. The distribution plate 13 is provided with a plurality of small holes, and the ash return port is one of the above-mentioned small holes. The axis of the ash return port is perpendicular to the distribution plate, and the returned fly ash can be blown into the high temperature zone. Figure 2 , using high temperature and oxygen to reheat, crack, burn and gasify the fly ash, so that the fly ash is recycled to the gasifier 14 for reuse, thereby improving the carbon conversion rate. In other embodiments, there can also be multiple ash return ports.

[0082] In the present embodiment, the sending tank 1 is a pressurized storage tank with a filter at its bottom. In other embodiments, the bottom of the sending tank 1 may be equipped with a cyclone separator or may not be equipped with a filter component. In the present embodiment, conventionally, the pressurized gas in the sending tank 1 is achieved by adding a carrier gas inlet. The carrier gas is CO2. The CO2 can be derived from the output of the gasifier 14. In other embodiments, the carrier gas can also be nitrogen. In the present embodiment, an aeration cone 2 is provided in the delivery tank 1. The aeration cone 2 is located at the outlet of the delivery tank 1. The aeration cone 2 is used to form a fluidized state of fly ash. After the fly ash and CO2 gas form a fluidized state through the aeration cone 2, the fly ash falls into the accelerator 4. With the appropriate amount of CO2 gas introduced into the accelerator 4, the fly ash is transported to subsequent components. In the present embodiment, the aeration cone 2 is connected to the bottom of the delivery tank 1 by a flange. In other embodiments, other connection methods can also be adopted.

[0083] In this embodiment, accelerator 4 is connected to a gas pipeline equipped with a shut-off valve 40. In this embodiment, the material flow rate can be controlled by controlling the opening of valve 5, primarily to reduce the flow rate, while the material flow rate can be controlled by controlling the pressure of the external gas pipeline, primarily to increase the flow rate. In this embodiment, the gas blown into the external gas pipeline is CO2, which can be derived from the output of gasifier 14. In other embodiments, nitrogen can also be used.

[0084] In this embodiment, Figure 3 The accelerator 4 is divided into three layers, which are the pressure pipe layer 41, the ventilation layer 42 and the support skeleton layer 43 from the outside to the inside. There is a gap between the pressure pipe layer 41 and the ventilation layer 42, and the ventilation layer 42 and the support skeleton layer 43 are almost tightly fitted. In this embodiment, the external pressure pipe layer 41 is a metal pipe and is connected to the gas pipeline. In this embodiment, the ventilation layer 42 in the middle contains a large number of ventilation holes. The diameter of the ventilation holes is very small, up to 0.2μm, which only allows gas to enter the interior from the outside through the ventilation layer 42 and then fully mix with the falling powder. The material of this layer is ceramic. In other embodiments, its diameter can be any value from 0.1 to 2.0μm, and the material can be ceramic, metal sintering or non-metallic filter cloth, etc. In this embodiment, in order to prevent the ventilation layer 42 from being damaged by vibration and to prevent it from being worn, a support skeleton layer 43 is set inside the ventilation layer. The support skeleton layer 43 is a metal mesh support structure. In this embodiment, the accelerator 4 must be installed vertically to the ground. The ash on the top falls into the accelerator 4 by gravity and meets the gas during the falling process. Since the ventilation layer 42 contains a large number of dense micron pores, the gas and solid are in very full contact, achieving the purpose of full mixing. Due to the full mixing, subsequent transportation can be carried out by dense phase transportation.

[0085] In this embodiment, the control assembly is electrically connected to the control valve 5, speedometer 6, and density meter 7, which are sequentially arranged along the conveying pipeline. The control assembly is also electrically connected to the shut-off valve 40. The speedometer 6 and density meter 7 are used to detect the mass of the fly ash delivered to the gasifier 14 within a preset time. The shut-off valve 40 and the control valve 5 are used to adjust the mass of the fly ash delivered to the gasifier 14 within a preset time. In this embodiment, the control assembly is also electrically connected to a pressure gauge 8 and a thermometer 9, which are located in the conveying pipeline. The pressure gauge 8 is used to detect the pressure within the conveying pipeline, and the thermometer 9 is used to detect the temperature within the conveying pipeline. In this embodiment, there are three pressure gauges 8: one for detecting the pressure at the top of the sending tank 1; one located upstream of the connection between the conveying sub-pipeline and the conveying pipeline, for detecting the pressure in the conveying pipeline; and one for detecting the pressure within the gasifier 14.

[0086] In this embodiment, the conveying pipeline is also equipped with a first shut-off valve 3, located between the ash outlet of the conveying tank 1 and the accelerator 4, for controlling the flow of the conveying pipeline. The system also includes a switching valve 11 and an ash silo 16. The ash silo 16 is connected to the conveying pipeline via a conveying sub-pipeline. The switching valve 11 is located at the junction of the conveying sub-pipeline and the conveying pipeline, i.e., the bifurcation. The ash silo 16 is used to store fly ash. The switching valve 11 is used to connect the conveying pipeline and the conveying sub-pipeline when the gasifier 14 reaches a preset ash return stop condition, allowing the fly ash to enter the ash silo 16. In this embodiment, the system also includes a second shut-off valve 10, located between the bifurcation and the ash return outlet, for controlling the flow of the conveying pipeline. In this embodiment, the conveying sub-pipeline is also connected to an external air pipe, which is equipped with an ash silo protection valve 15 for controlling the flow of the third ventilation pipe. In this embodiment, the ash return outlet is also connected to an outlet pipe, which is equipped with an ash return protection valve 12 for controlling the flow of the outlet pipe.

[0087] Comparative Example 1

[0088] The difference from Example 1 is that, in this comparative example, Figure 4 The accelerator 4' includes a rotary feeder 44' and a gas pipe 45' is provided at the bend of the conveying pipeline to introduce gas to fluidize the fly ash and achieve the purpose of pneumatic conveying. No detection instrument is used downstream to feedback the conveying situation, so the precision control is poor. The only way is to increase the conveying gas volume, resulting in a larger gas-to-solid ratio value and a large gas consumption. In addition, the conveying method is generally dilute phase conveying.

[0089] Example 2

[0090] A fluidized bed gasification control method is implemented by the fluidized bed gasification system of Example 1 or Comparative Example 1. The control process is displayed on the DCS system and can be operated and adjusted. The method comprises the following steps:

[0091] S1, control the conveying tank 1 to convey fly ash to the ash return port through the conveying pipeline, the specific steps are as follows:

[0092] S11, close the first shut-off valve 3 and the second shut-off valve 10, and open the ash return protection valve 12 to prevent the high-temperature and high-pressure materials inside the gasifier 14 from returning to the pipeline and causing accidents such as fire and explosion;

[0093] S12, open the shut-off valve 40 on the gas pipeline connected to the accelerator 4 / 4', and open the control valve 5. At this time, the opening of the control valve 5 can reach the maximum;

[0094] S13. When the pressure detected by the pressure gauge 8 is higher than the pressure in the gasifier 14, the second shut-off valve 10 is opened, and then the ash return protection valve 12 is closed. If the pressure detected by the pressure gauge 8 is not higher than the pressure in the gasifier 14, the second shut-off valve 10 is not allowed to be opened.

[0095] S14: When the pressure detected by the pressure gauge 8 is continuously higher than the pressure in the gasifier 14, it indicates that the conveying pipeline is unobstructed. The first shut-off valve 3 is opened to control the conveying tank 1 to convey fly ash into the conveying pipeline. When the reading of the thermometer 9 changes, it indicates that the fly ash has been conveyed into the gasifier 14.

[0096] S2. The mass information of the fly ash transported to the gasifier 14 within a preset time is detected by the density meter 7 and the speed meter 6; the mass of the ash circulated from the gasifier to the gasifier per hour is: fly ash mass flow rate (kg / h) = density (kg / m 3 )×speed (m / s)×pipe cross-sectional area (m 2 )×3600s / h-mass flow rate of conveying gas (kg / h), the conveying gas speed is generally 7m / s.

[0097] S3. Adjust the quality of the fly ash delivered to the gasifier 14 within a preset time according to the quality information and preset control conditions.

[0098] S4. When the gasifier 14 reaches the preset ash return stop condition, the second shut-off valve 10 is closed and the switching valve 11 is opened to allow the fly ash to enter the ash storage 16.

[0099] In this embodiment, if the pressure detected by the pressure gauge 8 is higher than the pressure inside the gasifier 14 and is consistent with the pressure of the conveying gas, it means that the conveying pipeline is blocked and needs to be unblocked, otherwise the entire process cannot proceed.

[0100] In this embodiment, before officially transporting fly ash to the gasifier 14, it is possible to first confirm whether the transportation pipeline is unobstructed. The specific method is: close the first shut-off valve 3, open the external gas pipeline of the accelerator 4 / 4', at this time the opening of the control valve 5 can reach the maximum, open the second shut-off valve 10, and observe whether the pressure detected by the pressure gauge 8 is higher than the pressure of the gasifier 14 and lower than the transportation gas pressure, indicating that the pipeline is unobstructed; if the pressure detected by the pressure gauge 8 is lower or consistent with the transportation gas pressure, it means that the transportation pipeline is blocked and needs to be unblocked before transporting the fly ash.

[0101] In this embodiment, after the gasifier 14 operates normally, that is, when the operating temperature of the gasifier 14 is above 900°C and the coal feed load is above 60% (that is, the ratio of the coal feed amount under the actual operating conditions of the gasifier to the coal feed amount under 100% design conditions reaches 60%), the circulation control operation can be performed.

[0102] Effect Example 1

[0103] 1. A fluidized bed gasifier identical to that used in Example 1, but without a circulation control system, was operated under the following operating conditions: 35 t / h of coal was fed, with a fixed carbon content of 60 wt%, and an ash content of 8 wt%. During operation, the fly ash discharge rate was 6 t / h, with a fixed carbon content of 80 wt%. The operating results showed a slag discharge rate of 2.9 t / h, a fixed carbon content of 3 wt%, a carbon conversion rate of 76.7%, and a CO content of 26.2 vol% in the crude coal gas.

[0104] 2. The fluidized bed gasifier circulation control system in Example 1 and the fluidized bed gasifier circulation control method in Example 2 were used and operated under the following operating conditions: the coal mass fed into the furnace was 32.5 t / h, the fixed carbon content of the coal was 60 wt%, the ash content of the coal was 8 wt%; the fly ash volume was 3.15 t / h, and the gas consumption was 49 Nm 3 / h, gas-solid ratio 6.2 (gas consumption volume flow rate 10.9m 3 / h÷actual volume flow of fly ash 1.75m 3 Operational results: 2.9 t / h of slag discharge, 3 wt% fixed carbon content in the slag, no fly ash emission, a carbon conversion rate of 99.5%, and a CO content of 28.3 vol% in the crude coal gas.

[0105] 3. The fluidized bed gasifier circulation control system in Comparative Example 1 and the fluidized bed gasifier circulation control method in Example 2 were used and operated under the following operating conditions: the coal mass fed into the furnace was 32.5 t / h, the fixed carbon content of the coal was 60 wt%, the ash content of the coal was 8 wt%; the fly ash volume was 3.15 t / h, and the gas consumption was 775 Nm 3 / h, gas-solid ratio 31.7 (gas consumption volume flow 55.5m 3 / h÷actual volume flow rate of fly ash 1.75m 3 / h), dilute phase conveying. Operational results: slag discharge of approximately 2.9 t / h, fixed carbon of approximately 3%, virtually no fly ash emissions, a carbon conversion rate of approximately 99.5%, and a CO content of 23.0 vol% in the crude coal gas. This indicates that when traditional pneumatic conveying is used in the gasifier of the present invention, excessive conveying gas (inert gas) cools the high-temperature fly ash, hindering the gasification reaction for fly ash conversion and resulting in heat loss, which adversely affects the CO content.

[0106] Effect Example 2

[0107] 1. A fluidized bed gasifier identical to that used in Example 1, but without a circulation control system, was operated under the following conditions: 11 t / h of coal was fed, with a fixed carbon content of 50 wt%, and an ash content of 18 wt%. During operation, the fly ash discharge rate was 2 t / h, with a fixed carbon content of 65 wt%. The operating results showed a slag discharge rate of 2.5 t / h, a fixed carbon content of 3 wt%, a carbon conversion rate of 75.2%, and a CO content of 24.2 vol% in the crude coal gas.

[0108] 2. The fluidized bed gasifier circulation control system in Example 1 and the fluidized bed gasifier circulation control method in Example 2 were used and operated under the following operating conditions: the coal mass fed into the furnace was 9 t / h, the fixed carbon content of the coal was 50 wt%, the ash content of the coal was 18 wt%; the fly ash volume was 3.15 t / h, and the gas consumption was 49 Nm 3 / h, gas-solid ratio 6.2 (gas consumption volume flow rate 10.9m 3 / h÷actual volume flow of fly ash 1.75m 3 Operational results: 2.5 t / h of slag discharge, 3 wt% fixed carbon content in the slag, no fly ash emission, a carbon conversion rate of 98.6%, and a CO content of 27.6 vol% in the crude coal gas.

[0109] 3. The fluidized bed gasifier circulation control system in Comparative Example 1 and the fluidized bed gasifier circulation control method in Example 2 were used and operated under the following operating conditions: the coal mass fed into the furnace was 9 t / h, the fixed carbon content of the coal was 50 wt%, the ash content of the coal was 18 wt%; the fly ash volume was 3.15 t / h, and the gas consumption was 250 Nm 3 / h, gas-solid ratio 6.2 (gas consumption volume flow rate 10.9m 3 / h÷actual volume flow rate of fly ash 1.75m 3 Operational results: 2.5 t / h of slag discharge, 3 wt% fixed carbon content in the slag, no fly ash emission, a carbon conversion rate of 98.6%, and a CO content of 21.5 vol% in the crude coal gas.

[0110] Although specific embodiments of the present invention have been described above, those skilled in the art will appreciate that these are merely illustrative and that the scope of protection of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, and such changes and modifications are intended to fall within the scope of protection of the present invention.

Claims

1. A fluidized bed gasification system, characterized in that: It includes a delivery tank, a delivery pipeline, a gasifier and a control component; The conveying tank is provided with an ash outlet, and the gasifier is provided with an ash return outlet, and the ash outlet and the ash return outlet are connected through the conveying pipeline; the conveying tank is used to convey fly ash to the gasifier; The delivery pipeline is provided with an accelerator and a control valve; the accelerator is coaxially provided with a pressure-bearing pipeline layer, a ventilation layer, and a support frame layer from the outside to the inside, with a gap between the pressure-bearing pipeline layer and the ventilation layer, and the pressure-bearing pipeline layer is connected to a gas pipeline; the gas pipeline is provided with a shut-off valve; the control valve is located downstream of the accelerator; The control assembly is electrically connected to the shut-off valve and the control valve, and is used to adjust the mass of the fly ash delivered to the gasifier.

2. The fluidized bed gasification system according to claim 1, characterized in that: The delivery pipeline is further provided with at least one of a speed meter, a density meter, a pressure meter and a thermometer, and the speed meter, the density meter, the pressure meter and the thermometer are all electrically connected to the control component.

3. The fluidized bed gasification system according to claim 1, characterized in that: The fluid channel of the accelerator is perpendicular to the ground; The material of the pressure-bearing pipe layer is metal; The ventilation layer is made of metal or ceramic; the ventilation layer is provided with a plurality of ventilation holes, and the diameter of the ventilation holes is 0.1-2.0 μm; The support skeleton layer is made of metal; the support skeleton layer is bonded to the ventilation layer; and the structure of the support skeleton layer is a mesh hollow structure.

4. The fluidized bed gasification system according to claim 1, characterized in that: An aeration cone is also provided between the ash outlet and the conveying pipe, for fluidizing the fly ash; The inflation cone is connected to the ash outlet flange.

5. The fluidized bed gasification system according to claim 1, characterized in that: The conveying pipeline is further provided with a first shut-off valve, which is located between the ash outlet and the accelerator and is used to control the on-off of the conveying pipeline.

6. The fluidized bed gasification system according to claim 1, characterized in that: The ash return port is also connected to an air outlet pipe, and the air outlet pipe is provided with an ash return protection valve for controlling the on-off of the air outlet pipe.

7. The fluidized bed gasification system according to claim 1, 2 or 5, characterized in that: It also includes an ash bin for storing fly ash; the ash bin is provided with an ash inlet, and the conveying pipeline is also provided with a bifurcation; The ash inlet and the bifurcation are connected through a conveying sub-pipeline; a switching valve is provided on the conveying sub-pipeline for connecting the conveying pipeline and the conveying sub-pipeline when the gasifier reaches a preset ash return stop condition, so that the fly ash enters the ash bin.

8. The fluidized bed gasification system according to claim 7, characterized in that: The conveying pipeline is further provided with a second shut-off valve, which is provided between the bifurcation and the ash return port and is used to control the on-off of the conveying pipeline.

9. The fluidized bed gasification system according to claim 7, characterized in that: The conveying sub-pipeline is also connected to an external air pipe, and the external air pipe is provided with an ash storage protection valve for controlling the on-off of the external air pipe.

10. The fluidized bed gasification system according to claim 1, characterized in that: The conveying tank is further provided with an ash supply port, and the gasifier is further provided with an ash discharge port. The ash supply port and the ash discharge port are connected via a circulation pipeline; a cooling device and a dust removal device are provided on the circulation pipeline.

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