Stokehole positive pressure feeding system

Abstract

A stokehole positive pressure feeding system comprises a stock bin, a surge bin, a first conveyor, a rotary feeding valve and a second conveyor which are sequentially arranged in the material conveying direction. And the output end of the second conveyor is connected with high-pressure reaction equipment. On one hand, uniform, continuous and stable conveying of the metering screw conveyor connected to the surge bin can be guaranteed, and the problems of material breakage, non-uniform discharging and the like are avoided; on the other hand, the reliability, safety and sealing performance of the high-pressure process needing feeding can be remarkably improved, the problems of leakage, backflow, equipment abrasion and the like are solved, and meanwhile operation flexibility and redundancy are provided; and high-temperature fuel gas generated by the gasification furnace can be prevented from flowing back to the feeding system.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of feeding systems, in particular to a kind of furnace front positive pressure feeding system. BACKGROUND

[0002] The existing positive pressure feeding system usually includes silo, feeding screw, rotary feeding valve and push material screw connected in sequence, for example, CN 210683701U discloses a kind of multi-element mixed biomass gasification positive pressure feeding system, including by upper and lower sequentially connected main belt conveyor, furnace front silo, center material taking machine, warehouse bottom metering screw conveyor, sealed rotary feeder and pressurized water cooling double screw conveyor;Center material taking machine is located at the bottom of furnace front silo, center material taking machine center turntable, rotary spring switch and driving motor;The rotary spring switch is fixed on the center turntable, and the motor drives the center turntable in turn to drive the rotary spring switch to turn, to realize flexible pushing biomass material;The sealed rotary feeder includes motor and rotary valve, and the rotary valve body is provided with cutter.

[0003] However, the system has the following defects: (1) the system is directly connected with center material taking machine at the output end of furnace front silo, which is prone to material breakage and uneven feeding;(2) pressurized water cooling double screw conveyor is not connected with sealing gas, which cannot capture the pressure fluctuation signal of furnace, adjust and control the air volume and pressure, and is prone to gas backflow from gasification furnace to feeding system;And the material is easily polluted by the internal atmosphere of gasification furnace. UTILITY MODEL CONTENT

[0004] The utility model aims at overcoming at least one of the above technical problems of prior art and providing a furnace front positive pressure feeding system with high safety and smooth and stable transportation.

[0005] The technical scheme of the utility model is: a kind of furnace front positive pressure feeding system, including silo, buffer bin, first conveyor, rotary feeding valve and second conveyor sequentially arranged along material conveying direction;The output end of the second conveyor is connected with high-pressure reaction equipment.

[0006] Further, the number of the rotary feeding valve is at least two, and each rotary feeding valve and adjacent rotary feeding valve are provided with first sealing gas inlet, and the first sealing gas inlet is communicated with the working cavity of the rotary feeding valve.

[0007] Further, the valve is provided between the rotary feeding valve and the second conveyor;Second sealing gas inlet is provided on the second conveyor and between the second conveyor and the valve.

[0008] Further, the second conveyor is a pushing screw conveyor, a water cooling jacket is arranged on the shell of the pushing screw conveyor; sealing gas enters the shell through the second sealing gas inlet to form annular sealing air, and the air outlet of the annular sealing air is provided with one or more, and is directed to the feeding port position of the high-pressure reaction equipment.

[0009] Further, a plurality of material taking screws are arranged at the bottom of the bin in a spaced manner, and the material taking screws are used to convey the material to the buffer bin, and the bin is provided with an even number of material taking screws according to the size of the material conveying capacity.

[0010] Further, the first conveyor is a metering screw conveyor; the buffer bin is provided with a high-level material level meter and a low-level material level meter, and the height of the high-level material level meter and the low-level material level meter is arranged in the range of 60%-80% of the volume of the buffer bin.

[0011] Further, the buffer bin is designed in a small volume and a large inclination angle, and the inclination angle is greater than or equal to 70 degrees.

[0012] Further, at least one pressure relief plate is arranged on the sidewall of the bin.

[0013] Further, the pushing screw conveyor is made of high-temperature resistant material at the end connected with the high-pressure reaction equipment.

[0014] Further, the valve is at least one of a pneumatic gate valve, an electric gate valve and a manual gate valve.

[0015] Further, the first conveyor is a metering screw conveyor, the metering screw conveyor is connected with the discharge port of the buffer bin, and is arranged horizontally or at an angle with the ground, and the angle is 8-15 degrees.

[0016] The beneficial effects of the utility model are as follows:

[0017] (1) the buffer bin is arranged between the bin and the first conveyor, so that the buffer bin can play a buffering role, the direct connection of the bin and the first conveyor can be prevented, and the phenomena of material breakage and uneven feeding can be prevented, so that the first conveyor can uniformly and stably convey, and the stable and continuous gasification of the gasification furnace is ensured;

[0018] (2) the high-level material level meter and the low-level material level meter arranged in the buffer bin can further ensure that the metering screw conveyor connected to the buffer bin can uniformly, continuously and stably convey;

[0019] (3) the sealing gas is introduced into the pushing screw conveyor and between the pushing screw conveyor and the pneumatic gate valve, so that the pressure fluctuation signal of the furnace can be sensitively captured, the air volume and pressure can be adjusted and controlled, the gas backflow from the gasification furnace to the feeding system can be prevented, the free fluctuation protection effect of the feeding system is improved, and the raw materials are protected from being polluted by the internal atmosphere of the gasification furnace;

[0020] (4) by the buffer bin is designed to small volume large inclination angle structure, can ensure that the buffer bin is not blocked, full of material;

[0021] (5) by the bottom of the bin configuration even form of material taking screw, can form a movable bottom, increase the mobility of fuel, and when the winding, can be through the positive and negative rotation material taking screw solution;

[0022] (6) by the inner wall of the bin set pressure reducing plate, can play the function of arch breaking, mixing and the like. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is the structural schematic diagram of the embodiment of the utility model;

[0024] Figure 2 is the front view of the positive pressure feeding system of the embodiment of the utility model;

[0025] Figure 3 is Figure 2 the side view of the embodiment shown in the figure;

[0026] Figure 4 is the structural schematic diagram of the material taking screw of the embodiment of the utility model;

[0027] Figure 5 is the effect drawing of the bin inside of the embodiment of the utility model.

[0028] BRIEF DESCRIPTION OF DRAWINGS

[0029] 1. bin;2. buffer bin;3. metering screw;4. rotary feeder valve;5. pneumatic gate valve;6. pusher screw;7. gasification furnace;11. material taking screw;12. pressure reducing plate;41. first rotary feeder valve;42. second rotary feeder valve. DETAILED DESCRIPTION

[0030] The utility model will be further explained in detail in the following in conjunction with the drawings and specific embodiments of the specification.

[0031] As Figures 1-3 shown: a furnace front positive pressure feeding system, including from top to bottom in turn connected bin 1, buffer bin 2, metering screw 3, rotary feeder valve 4, pneumatic gate valve 5 and pusher screw 6;The number of rotary feeder valve is at least two, the output end of pusher screw is connected high pressure reaction equipment;The pressure of feeding system is greater than the pressure in high pressure reaction equipment.

[0032] In the embodiment, high pressure reaction equipment is combustion furnace or gasification furnace etc., and the embodiment is preferably gasification furnace 7, and the material is biomass fuel.

[0033] In the embodiment, the positive pressure feeding system can be provided with one or more groups, preferably two groups, for example, symmetrically connected to the two sides of the gasifier, to simultaneously feed fuel into the gasifier, thereby greatly improving the working efficiency, and even if one group fails, fuel feeding can be carried out through the other group of the positive pressure feeding system.

[0034] Specifically, in the embodiment, the bunker 1 is preferably designed in a structure of large at the top and small at the bottom, to reduce the contact of the biomass fuel with the inner wall of the bunker, prevent the biomass from bridging, and avoid the local pressure of the material taking screw at the bottom of the bunker being too high, thereby causing overload or breakage, bending or deformation of the screw shaft, etc. Among them, as shown in the figure, a plurality of material taking screws 11 can be arranged at intervals at the bottom of the bunker, and the biomass fuel is fed to the buffer bin 2 below through the material taking screw. Figure 4 Preferably, the bunker 1 is configured with even-numbered material taking screws 11 such as four-axis or six-axis according to the size of the material conveying capacity, to form a movable bottom, increase the flowability of the fuel, and set a discharge port at each end of the bunker, and each discharge port can flexibly select the material taking screw for unloading. When winding occurs, it can be solved by reversing the material taking screw.

[0035] The side wall in the bunker 1 is also provided with a pressure relief plate 12, which can be arranged annularly around the inner wall of the bunker, or discontinuously at intervals. For example, when being arranged at intervals, one or more groups of pressure relief plate 12 units can be arranged at intervals along the annular wall of the bunker, and when being multiple groups, preferably 2-6 groups, each group of pressure relief plate 12 units includes a plurality of pressure relief plates 12 arranged longitudinally at intervals along the inner wall of the bunker, and the groups of pressure relief plate 12 units are symmetrically or staggered arranged. The pressure relief plate 12 is preferably designed in a structure with an inclined surface, which can be arc-shaped or linear. The pressure relief plates 12 jointly act to break the arch and mix the material.

[0036] In the embodiment, the buffer bin 2 serves as a buffer storage for fuel, to ensure that the metering screw conveyor 3 connected to the buffer bin can realize uniform, continuous and stable conveying, and avoid problems such as material breakage and uneven unloading. The buffer bin 2 is designed in a structure of large at the top and small at the bottom, and adopts a design of small volume and large inclination angle, to ensure that the buffer bin is not blocked and full of material. Specifically, the capacity of the buffer bin is 0.5m 3 , and the inclination angle is ≥70°, which refers to the included angle between the inclined surface at the inlet of the buffer bin and the horizontal plane.

[0037] In this embodiment, the buffer bin 2 is provided with a material level meter, which can control the material taking screw speed of the material bin 1 together with the metering screw 3, so that the material level of the buffer bin 2 is kept at a set value. Specifically, the material level meter can be a radio frequency admittance material level meter, a radar material level meter or a radiation material level meter. Two material level meters are provided in total, which are a high material level meter and a low material level meter, and are respectively installed in the upper part of the side wall of the buffer bin. The height of the material level meter is preferably set in the range of 60%-80% of the volume of the buffer bin, for example, the low material level meter is set at the height of 60% of the volume of the buffer bin, which is used to detect whether the material level is below the lower limit of the target range; the high material level meter is set at the height of 80% of the volume of the buffer bin, which is used to detect whether the material level exceeds the upper limit of the target range. When the metering screw 3 gradually increases the biomass conveying amount, the low material level meter in the buffer bin 2 detects that the material level decreases, and then sends the material level information to the control system, and the control system controls the material taking screw 11 to automatically increase the material taking screw speed (frequency conversion control) and increase the unloading amount of the material bin 1 into the buffer bin 2; on the contrary, when the high material level meter in the buffer bin detects that the material level is high, the control system controls the material taking screw 11 to automatically reduce the material taking screw speed, so as to ensure that the material level of the buffer bin is stable in the set value range. Since the electrical control of the control system is a conventional mature technology, it is not within the protection scope of the present application, and will not be described in detail here.

[0038] In this embodiment, the form of the metering screw 3 can be a tubular screw, a U-shaped screw or a chain plate machine, and the U-shaped screw is preferred. The metering screw 3 is connected with the discharge port of the buffer bin 2, and can be arranged horizontally or at a certain angle with the ground, and the angle is preferably 8-15°, and further preferably 9-12°. The metering screw adopts frequency conversion adjustment, which can adjust the fuel input amount in real time, so as to adjust or control the load change of the gasification furnace. Especially for complex and changeable biomass fuel, the accuracy is improved, which is more helpful to reasonably match the gasification air volume, and realizes the precise control and adjustment of the gasification furnace.

[0039] In this embodiment, the number of the rotary feeding valves 4 is preferably designed as two. It can be understood that if a higher pressure is wanted, such as 50kPag or more, three or more rotary feeding valves can be added.

[0040] Each rotary feeder valve has a pressurization function, that is, the first rotary feeder valve 41, the second rotary feeder valve 42, and both of them are supplied with sealing gas, and the high-temperature combustion gas generated by the gasifier can be effectively prevented from flowing back to the furnace front feeding system by adjusting and controlling the pressure of the sealing gas. The outlet of the first rotary feeder valve 41 is directly connected to the inlet of the second rotary feeder valve 42, or the connection is made through a sealing channel. The working chamber of the first rotary feeder valve, the working chamber of the second rotary feeder valve, and the channel between them are all connected to the sealing gas, which is communicated with the gas supply equipment through a pipeline. In this embodiment, by introducing sealing gas between each rotary feeder valve and the adjacent rotary feeder valve, the gas leakage of the rotary feeder valve can be greatly reduced to maintain the process integrity.

[0041] The pressure of the sealing gas should be slightly higher than the maximum process pressure to ensure that any leakage is the sealing gas entering the process, rather than the process gas leaking out. The pressure of the sealing gas is usually controlled within a certain range, which can vary depending on the design of the system, but is usually higher than the maximum operating pressure of the sealed system. The composition of the sealing gas is a gas used for inert atmosphere, such as nitrogen.

[0042] In this embodiment, one end of the pusher screw 6 is made of high-temperature heat-resistant steel and directly contacts the hearth of the gasifier. The shell of the pusher screw 6 has a water-cooled jacket. The shell of the screw is connected to the sealing air along the annular structure to form an annular sealing air, which can block or weaken the gas in the gasifier from entering the feeding system to some extent. The tuyere is directly opposite the feed inlet position of the gasifier to prevent dust from entering the shaft end and causing blockage. It can be said that the pusher screw of this embodiment adopts a positive pressure pressurization screw, which can capture the pressure fluctuation signal of the hearth more sensitively than the existing normal pressure screw, and can adjust and control the air volume and pressure, and can prevent gas from flowing back from the gasifier to the feeding system.

[0043] In this embodiment, a pneumatic gate valve 5 is also provided on the connecting pipeline between the terminal rotary feeder valve (i.e. the second rotary feeder valve) and the pusher screw 6, and sealing gas is also introduced into the pipeline between the pneumatic gate valve 5 and the pusher screw 6. By introducing sealing gas between the pneumatic gate valve and the pusher screw and into the pusher screw, the free fluctuation protection effect of the feeding system can be further improved, and free fluctuation can be prevented. The free fluctuation refers to the unintentional movement or backflow of gas or particles due to the pressure difference in the system. In the context of high-pressure gasification solid feeding system, the sealing gas is used to create a barrier to prevent gas from flowing back from the gasifier to the feeding system.

[0044] It can be understood that the pneumatic gate valve can also be replaced by other valves, such as an electric gate valve, a pneumatic gate valve + a manual gate valve, or an electric gate valve + a manual gate valve.

[0045] The working principle of the embodiment is as follows: biomass fuel is placed in the stock bin 1, the stock bin 1 is a normal pressure stock bin, the fuel is broken arch and mixed after passing through each pressure reducing plate 12 of the stock bin, and then smoothly enters the material taking screw 11 at the bottom of the stock bin, the rotation speed of the material taking screw 11 is controlled by the material level meter on the buffer bin 2 and the metering screw machine 3, so as to prevent the buffer bin 2 or the metering screw machine 3 from being blocked; the fuel is broken after passing through the material taking screw 11 and then output into the buffer bin 2, the buffer bin 2 serves as a buffer storage for the fuel, so as to ensure that the metering screw machine connected to the buffer bin can realize uniform, continuous and stable conveying, the buffered fuel enters the metering screw machine 3, the metering screw machine 3 adjusts the fuel input in real time through frequency conversion control, so as to ensure uniform, continuous and stable conveying to the rotary feed valve; when the fuel enters the first rotary feed valve 41, the fuel is broken under the action of the cutter in the valve, and the inner cavities of the first rotary feed valve 41 and the second rotary feed valve 42 and the space between the two are input with sealing gas, such as nitrogen, the two rotary feed valves are always in a positive pressure state, that is, the pressure is higher than the pressure in the gasification furnace, so as to ensure that the biomass fuel is continuously, stably and reliably fed into the gasification furnace under the condition of positive pressure; the fuel broken by the two rotary feed valves enters the pushing screw machine 6 through the pneumatic gate valve 5, and then is fed into the gasification furnace 7 by the pushing screw machine 6, so as to ensure that the biomass fuel is continuously, stably and reliably fed into the gasification furnace under the condition of positive pressure; meanwhile, sealing gas, such as nitrogen, is input between the pneumatic gate valve and the pushing screw machine and in the annular cavity of the pushing screw machine during the working process, so as to prevent the high-temperature combustion gas generated by the gasification furnace from flowing back to the feeding system.

[0046] In summary, on the one hand, the buffer bin is added between the stock bin and the metering screw machine, so that the metering screw machine connected to the buffer bin can realize uniform, continuous and stable conveying, and problems such as material breakage and uneven feeding are avoided; on the other hand, a plurality of rotary feed valves are arranged, sealing gas is input into each rotary feed valve and between adjacent rotary feed valves, and sealing gas is input into the pushing screw machine and between the pushing screw machine and the pneumatic gate valve, so as to not only significantly improve the reliability, safety and efficiency of the high-pressure feeding process, reduce problems such as leakage, backflow and equipment wear, and provide flexibility and redundancy of operation, but also prevent the high-temperature combustion gas generated by the gasification furnace from flowing back to the feeding system.

[0047] The above merely describes a specific implementation of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical range disclosed in the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A front-of-furnace pressure positive feeding system, characterized in that, The device comprises a stock bin, a buffer bin, a first conveyor, a rotary feeder valve and a second conveyor arranged in sequence along the material conveying direction; the output end of the second conveyor is connected to a high-pressure reaction device; the bottom of the stock bin is arranged with multiple material taking screws at intervals, which convey the material to the buffer bin through the material taking screws; the stock bin is configured with an even number of material taking screws according to the size of the material conveying capacity; the first conveyor is a metering screw conveyor; the buffer bin is provided with a high-level material level meter and a low-level material level meter, and the heights of the high-level material level meter and the low-level material level meter are set in the range of 60%-80% of the volume of the buffer bin.

2. The front-of-furnace positive pressure feeding system according to claim 1, characterized in that, The number of the rotary feeder valve is at least two, and each rotary feeder valve and the adjacent rotary feeder valve are provided with a first sealing gas inlet, which is communicated with the working chamber of the rotary feeder valve.

3. The front-of-furnace positive pressure feeding system according to claim 1, characterized in that, A valve is arranged between the rotary feeder valve and the second conveyor; the second conveyor is provided with a second sealing gas inlet, and the second sealing gas inlet is arranged between the second conveyor and the valve.

4. The front fed pressurized feeding system according to claim 3, wherein, The second conveyor is a push screw conveyor, and the shell of the push screw conveyor is provided with a water cooling jacket; the sealing gas enters the shell through the second sealing gas inlet to form annular sealing air, and the air outlet of the annular sealing air is provided with one or more outlets, which are directed to the inlet position of the high-pressure reaction device.

5. The front-of-furnace positive pressure feeding system of claim 1, wherein, The buffer bin adopts a design of small volume and large inclination angle, and the inclination angle is greater than or equal to 70°.

6. The front-of-furnace positive pressure feeding system of claim 1, wherein, At least one pressure relief plate is arranged on the sidewall of the stock bin.

7. The front-fed, positive pressure feeding system of claim 4, wherein, The push screw conveyor at the end connected to the high-pressure reaction device adopts a high-temperature resistant material; the valve is at least one of a pneumatic gate valve, an electric gate valve and a manual gate valve.

8. The front-of-furnace positive pressure feeding system of claim 1, wherein, The first conveyor is a metering screw conveyor, which is connected to the discharge port of the buffer bin and is arranged horizontally or at an angle with the ground, and the angle is 8-15°.

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