Device for improving gasification thermal efficiency of biomass gasifier

Abstract

The invention provides a device for improving gasification thermal efficiency of a biomass gasification furnace, and relates to the technical field of biomass gasification furnaces, the device comprises a flow opening degree adjusting electric valve, an air inlet arranged at the gasification furnace, a pyrolysis zone, and a plurality of thermocouples arranged at the junction of a reduction zone and an oxidation zone, and when the temperature detected by the thermocouples is higher than a preset temperature, the thermocouples are switched off. The flow opening degree adjusting electric valve can adjust the air inflow of the air inlet. The air inflow of the air inlet directly affects the oxygen content in the gasification furnace, so that the temperature of the gasification furnace can be adjusted, and heat energy loss is reduced. Before biomass raw materials enter the gasification furnace, the dryer is used for drying the biomass raw materials and reducing the water content, the cooling circulation system is arranged on the furnace, when the humidity in the gasification furnace exceeds the preset humidity, air in the gasification furnace is introduced into the cooling circulation system through the induced draft fan, and water in the air is condensed in the coil pipe and discharged; the water removal effect is achieved, and the gasification heat efficiency is comprehensively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of biomass gasifiers, and in particular to a device for improving the gasification thermal efficiency of a biomass gasifier. Background Art

[0002] Biomass gasifier is a device that converts biomass materials into combustible gas. The gasification heat efficiency of the gasifier is one of the important indicators to measure its performance, which reflects the energy conversion efficiency in the gasification process. However, the gasification heat efficiency of existing biomass gasifiers is often only 70-80%, which does not reach the ideal calorific value. The main reasons for this phenomenon include the following points.

[0003] First, biomass raw materials usually have a high moisture content. A high moisture content means that the actual proportion of raw materials is low, which leads to a decrease in the thermal efficiency of gasification. For this reason, the existing gasifier generally dries the biomass raw materials in the furnace body first. For example, patent CN103666570A discloses a self-drying biomass gasification system. The water-containing biomass raw materials enter the vertical updraft gasifier, and use the high-temperature circulating gas to rise in the furnace through the drying layer and then continue to rise. On the way, it moves in the opposite direction of the raw materials falling from the drop pipe, realizing the self-drying function of the biomass raw materials. However, during the drying process of the biomass raw materials, the water vapor generated accumulates in the furnace. The process of converting water into steam is an endothermic process. As the biomass raw materials are further thermally cracked, gasified and burned, the steam continues to absorb heat until it is discharged from the boiler. This process will take away a large amount of heat energy that has not been used, resulting in heat energy loss.

[0004] Common fixed updraft and downdraft gasifiers mainly for heat supply, the biomass raw materials are input from the top of the furnace, the gasifier (air) is input from the bottom of the furnace by the blower, the combustible gas is output from the side of the furnace top, and the ash is discharged from the side of the furnace bottom. After the raw materials enter the gasifier, the working temperature of the drying layer is about 200-300℃, which is mainly used to remove moisture. After passing through the thermal cracking layer, the working temperature is about 500-700℃, which is mainly for the material to overflow the combustible gas and produce charcoal at the same time. After passing through the reduction layer and oxidation layer, the working temperature can reach about 700-1200℃. This structural arrangement will produce the following phenomena: the maximum temperature of the furnace reaches 1100-1200℃, and the temperature of the furnace is too high, causing the charcoal produced after the thermal cracking of the biomass to burn into ash. At this time, the high temperature generated is not used as effective heat output, and the actual output heat energy is only 100-200℃ combustible gas, resulting in heat energy loss.

[0005] Secondly, when biomass raw materials are gasified in the gasifier, tar will be produced. The tar will be entrained by the combustible gas and discharged from the output pipe. During the discharge process, the tar will solidify on the inner wall of the output pipe. On the one hand, the heat energy contained in the tar itself accounts for more than 10% of the total heat energy of the combustible gas, and the solidification of the tar will lead to direct loss of heat energy; on the other hand, the solidification of the tar will cause the output pipe to be blocked, affecting the output of the combustible gas, reducing the heat of the combustible gas, and further reducing the thermal efficiency of gasification.

[0006] In view of this, how to provide a device that can improve the gasification thermal efficiency of a biomass gasifier is a problem that technical personnel in this field need to solve urgently. Summary of the invention

[0007] The purpose of the present invention is to provide a device for improving the gasification thermal efficiency of a biomass gasifier, so as to solve the problems existing in the prior art.

[0008] To achieve the above object, the present invention provides a device for improving the gasification thermal efficiency of a biomass gasifier, wherein a drying zone, a pyrolysis zone, a reduction zone and an oxidation zone are defined inside the gasifier, and the device comprises:

[0009] A flow opening regulating electric valve is provided at the air inlet of the gasifier, and a plurality of thermocouples are arranged at the pyrolysis zone and at the junction of the reduction zone and the oxidation zone. When the temperature detected by the thermocouple is higher than the preset temperature, the flow opening regulating electric valve can adjust the air intake of the air inlet.

[0010] Furthermore, it also includes:

[0011] The dryer is used to reduce or remove moisture in the biomass raw material, and the discharge port of the dryer is connected to the inlet of the gasifier.

[0012] Further, the dryer comprises:

[0013] The drying cylinder is obliquely arranged on the foundation pier, the higher end of which is the first end face, the lower end of which is the second end face, the feed inlet is opened at the first end face, the discharge outlet is opened at the second end face, and the drying cylinder is driven to rotate by a driving device;

[0014] A hot air inlet pipe is arranged on the second end surface and is connected to the drying cylinder. The gasifier has an output pipe, which is connected to the pyrolysis zone and is used to output combustible gas with a temperature higher than 300°C to the boiler. The hot air inlet pipe is connected to the tail gas outlet of the boiler.

[0015] The hot air outlet pipe is arranged on the first end surface and is connected with the drying cylinder.

[0016] Furthermore, the biomass raw material is fed into the feed port through an elevator, and both the elevator and the discharge port are provided with a microwave moisture meter.

[0017] Furthermore, it also includes: an air preheater, which is connected to the tail gas outlet of the boiler, and the air preheater is used to heat the air and transport it to the air inlet and / or hot air inlet pipe of the gasifier.

[0018] Furthermore, it also includes:

[0019] A humidity sensor is disposed in the gasifier and close to the top thereof, and is used to monitor the humidity of the top of the gasifier;

[0020] The cooling circulation system is used to circulate the air in the gasifier and remove moisture from the air when the humidity sensor detects that the humidity at the top of the gasifier is higher than a preset humidity.

[0021] Furthermore, the cooling circulation system comprises:

[0022] An air inlet pipe is connected to the gasifier, and the connection point is close to the top of the gasifier;

[0023] A coil, connected to the air inlet pipe and coiled on a mounting frame, wherein the mounting frame is fixedly mounted on an outer surface of the gasifier;

[0024] A tee pipe, a first end of which is connected to the coil, and a second end of which is vertically arranged and used for discharging cooling water and cooling tar in the coil;

[0025] The return air duct is connected to the third end of the three-way pipe, the return air duct is connected to the gasifier and an induced draft fan is arranged on the return air duct.

[0026] Furthermore, the mounting frame is fixedly arranged on the top of the gasifier, and the air inlet duct extends upward and is connected with the coil.

[0027] Furthermore, the gasifier is one of square, round, upper round and lower square, or upper round and lower round.

[0028] The present invention discloses the following technical effects:

[0029] 1. The combustible gas output pipeline is set in the pyrolysis zone, which is the main area where combustible gas and charcoal are produced, so that the combustible gas can be output at a temperature of about 300°C or above (about 400°C). Compared with the existing gasifier that outputs combustible gas at 100-200°C, the increased temperature of the combustible gas output in this application can avoid tar solidification, so that it can be output together with the combustible gas in the form of gas, reducing heat energy loss, avoiding blockage of the output pipeline, ensuring smooth output of the combustible gas, thereby increasing the output heat energy and improving the thermal efficiency of gasification.

[0030] 2. Before the biomass raw materials enter the gasifier, the biomass raw materials are dried by a dryer. Before drying, the moisture content of the biomass raw materials is detected by a microwave moisture meter to set appropriate drying parameters; after the biomass raw materials are dried, their moisture content is greatly reduced, which is conducive to improving the thermal efficiency of gasification. In addition, the heat source of the dryer uses boiler exhaust gas, without additional energy consumption, with the advantages of green energy saving and environmental protection, and can be widely used in the field of gasifiers.

[0031] 3. After the biomass raw materials are dried, they may still contain a certain amount of moisture. Therefore, this application sets a cooling circulation system on the gasifier. When the humidity in the gasifier exceeds the preset humidity, the air in the gasifier is introduced into the cooling circulation system through the induced draft fan, and the moisture in the air is condensed in the coil and discharged, so as to achieve the effect of moisture removal and further improve the thermal efficiency of gasification. In addition, in the air intake duct part of the cooling circulation system, this application adopts an arrangement in which the air intake duct extends upward. During the process of the gasifier air rising along the air intake duct, the tar can solidify and flow back to the gasifier along the air intake duct, reducing the heat energy loss of the tar.

[0032] 4. The present application monitors the temperature inside the gasifier through a thermocouple. When the temperature of the gasifier is too high, the air intake of the air inlet is controlled by adjusting the flow opening of the electric valve. The air intake of the air inlet directly affects the oxygen content in the gasifier, thereby adjusting the temperature of the gasifier and reducing heat energy loss.

[0033] 5. In addition to being used to dry the biomass raw materials, the exhaust gas of the boiler is also used to heat the air entering the gasifier from the air inlet. In contrast to the prior art, which uses room temperature air to directly enter the gasifier, this application can save part of the energy consumption used to heat the air and improve the thermal efficiency of gasification. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 It is a schematic diagram of the gasifier structure;

[0036] Figure 2 This is a schematic diagram of coil installation;

[0037] Figure 3 It is a schematic diagram of the dryer structure;

[0038] Among them, 1. gasification furnace; 101. drying zone; 102. pyrolysis zone; 103. reduction zone; 104. oxidation zone; 105. air inlet; 2. output pipeline; 3. drying cylinder; 4. foundation pier; 5. feed port; 6. discharge port; 7. hot air inlet pipe; 8. hot air outlet pipe; 9. air inlet pipe; 10. coil; 11. tee pipe; 12. return air pipe; 13. induced draft fan; 14. mounting frame. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] The embodiment of the present invention provides a device for improving the gasification thermal efficiency of a biomass gasifier. A drying zone 101, a pyrolysis zone 102, a reduction zone 103 and an oxidation zone 104 are defined inside the gasifier 1. In this embodiment, the gasifier 1 can be square, circular, upper circular and lower square, or upper circular. The model of the gasifier 1 can be a biomass fixed type (upper suction type, lower suction type, middle suction type), horizontal, rotary, circulating fluidized bed type, internal heating type, external heating type, etc. A flow opening regulating electric valve is provided at the air inlet 105 of the gasifier 1. A plurality of thermocouples are arranged at the junction of the pyrolysis zone 102 and the reduction zone 103 and the oxidation zone 104. The thermocouples are used to monitor the real-time temperature of each position in the gasifier 1. When the temperature detected by the thermocouple is higher than the preset temperature, the flow opening regulating electric valve can adjust the air intake of the air inlet 105. By adjusting the air intake, the phenomenon that the temperature of the gasifier 1 is too high and the heat cannot be fully utilized can be reduced as much as possible, and the charcoal produced after the pyrolysis of the biomass raw material can be preserved and will not be completely burned into ashes.

[0042] The dryer is used to remove most of the moisture in the biomass raw material to prevent the biomass raw material with high moisture content from directly entering the gasifier 1 . The discharge port 6 of the dryer is connected to the inlet of the gasifier 1 . The dryer includes: a drying cylinder 3, which is tiltedly arranged on a foundation pier 4, with a higher end thereof being a first end face and a lower end thereof being a second end face, a feed port 5 being arranged on the first end face, and a discharge port 6 being arranged on the second end face, the drying cylinder 3 being driven to rotate by a driving device, specifically, the output end of the driving device is connected to a transmission gear, a driven gear is fixedly arranged on the outer surface of the drying cylinder 3, and the driving device drives the drying cylinder 3 to rotate through the transmission gear and the driven gear; a hot air inlet pipe 7 is arranged on the second end face and communicated with the drying cylinder 3, an output pipe 2 is communicated with a pyrolysis zone 102, and the output pipe 2 is used to output combustible gas to the outside, specifically, the output pipe 2 can be used to heat and generate electricity with a combustible gas boiler; combustible gas can be mixed and burned with biogas; it can be coupled with a coal gas direct-fired boiler for heating and power generation; it can be coupled with a biomass direct-fired boiler (including a garbage incinerator, etc.), including a combustible gas and a coke, charcoal direct-fired boiler. It can also be coupled with various kilns, cement kilns, glass pool melting furnaces, etc., which directly burn combustible gas to perform work. In this embodiment, the output pipe 2 is used to output combustible gas with a temperature higher than 300°C (about 400°C) to the boiler. The hot air inlet pipe 7 is connected to the tail gas outlet of the boiler; the hot air outlet pipe 8 is arranged on the first end face and connected to the drying cylinder 3. It should be noted that the drying cylinder 3 maintains a connection relationship with the feed port 5, the discharge port 6, the hot air inlet pipe 7 and the hot air outlet pipe 8 in a rotating state. The existing structure is adopted here, and the specific connection relationship is not repeated. The biomass raw material is fed into the feed port 5 through a hoist. The hoist and the discharge port 6 are both provided with a microwave moisture meter for detecting the moisture content of the biomass raw material. Different drying schemes can be formulated according to different moisture contents. For example, when the moisture content is high, the rotation speed of the drying cylinder 3 can be reduced to make the biomass raw material slowly roll toward the discharge port 6. At the same time, the air inlet flow rate of the hot air inlet pipe 7 is increased, the drying time of the biomass raw material is extended, the drying effect is improved, and the moisture content is ensured to be reduced to a suitable value. This embodiment adopts the method of moving the biomass raw material and the hot air object, that is, the moving direction of the biomass raw material is opposite to the flow direction of the hot air, which improves the drying efficiency. This embodiment uses the waste heat of boiler tail gas to replace the conventional heat source to dry the biomass raw material, which has advantages in energy saving and emission reduction.

[0043] In this embodiment, it also includes: an air preheater, which is connected to the tail gas outlet of the boiler, and is used to heat the air and transport it to the hot air inlet pipe 7 and the air inlet 105 of the gasifier 1. The air preheater uses the tail gas of the boiler to heat the clean air, and there is a certain amount of heat loss in the process. If the clean air can reach the ideal temperature after heating, the clean air is transported to the dryer and the air inlet 105. If the temperature of the clean air is insufficient after heating, the tail gas of the boiler is directly transported to the dryer. At this time, the air preheater is only used for preheating the air at the air inlet 105.

[0044] In this embodiment, it also includes: a humidity sensor, which is arranged in the gasifier 1 and close to its top, and is used to monitor the humidity at the top of the gasifier 1; a cooling circulation system, and a dryer can remove most of the moisture. A small amount of moisture still exists in the biomass raw material. As the temperature in the gasifier 1 gradually increases, this part of the moisture will turn into water vapor and gather in the top area of ​​the gasifier 1. When the humidity sensor detects that the humidity at the top of the gasifier 1 is higher than the preset humidity, the cooling circulation system is automatically turned on to circulate the air in the gasifier 1 and remove moisture from the air. Under the joint action of the cooling circulation system and the dryer, the moisture content ratio of the biomass raw material before drying is almost the same as the thermal efficiency improvement. The cooling circulation system includes: an air intake pipe 9, which is connected to the gasifier 1, and the connection point is close to the top of the gasifier 1; a coil 10 is connected to the air intake pipe 9 and is coiled on a mounting frame 14, and the coil 10 is arranged in more than three layers. The mounting frame 14 is fixedly arranged on the outer surface of the gasifier 1. It should be noted that the mounting frame 14 is arranged along the outer edge of the gasifier 1 and is spaced from the entrance of the gasifier 1. The biomass raw material can smoothly enter the gasifier 1 from the entrance; a three-way pipe 11, the first end of which is connected to the coil 10 The second end is vertically arranged. When the air flows through the coil 10, the moisture and a small amount of tar in the air are liquefied and flow along the coil 10 to the position of the tee 11. The second end is used to discharge the cooling water and cooling tar in the coil 10. A collection box, a collection tank, etc. can be set below the second end to recycle the cooling water and tar. The return air duct 12 is connected to the third end of the tee 11. The return air duct 12 is connected to the gasifier 1 and an induced draft fan 13 is arranged on the return air duct 12. The mounting frame 14 is fixedly arranged on the top of the gasifier 1, and the air inlet duct 9 extends upward and is connected to the coil 10.

[0045] Specifically, the temperature of the pyrolysis zone 102 should be maintained at about 600°C, and the temperature at the junction of the reduction zone 103 and the oxidation zone 104 should be maintained at about 800°C. The air input amount of the air inlet 105 of the gasifier 1 is adjusted to maximize the calorific value and thermal efficiency of the gasification of the biomass raw material. In addition, the gasification of the biomass raw material can produce charcoal, and the calorific value of the charcoal is relatively high.

[0046] According to statistics, the conventional gasifier 1 gasifies wood chips with a moisture content of about 30%, and the calorific value of the combustible gas is measured by the steam production, and about 2.8 to 3.5 tons of steam are produced per ton of wood chips. The same raw material is gasified by this embodiment, and 150,000 kcal of heat can be consumed less in terms of removing moisture. In terms of charcoal consumption, about 1.2 million kcal of heat can be reduced. Tar is fed into the gas boiler together with the combustible gas in a gasified state, which increases the heat. After comprehensive factors are balanced, the total combustible gas combustion and the comprehensive heat energy can significantly improve the gasification thermal efficiency of the gasifier.

[0047] In some other embodiments, the device for improving the gasification thermal efficiency of a biomass gasifier disclosed in the present invention can also be applied to: gasifiers, carbonization furnaces, gas-carbon cogeneration furnaces, etc. for various types of biomass raw materials (including pellets). Including: direct combustion of biomass (including pellets) for heating, direct combustion of garbage for heating, power generation; garbage gasification for heat and power generation. Coal combustion, gasification for heating, coal gasification for coke production, coal gasification for heating and power generation, etc.

[0048] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0049] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A device for improving the thermal efficiency of biomass gasification furnace, wherein the gasification furnace (1) defines a drying zone (101), a pyrolysis zone (102), a reduction zone (103) and an oxidation zone (104), characterized in that: include: A flow rate opening regulating electric valve is provided at the air inlet (105) of the gasifier (1), and a plurality of thermocouples are arranged at the pyrolysis zone (102) and at the junction of the reduction zone (103) and the oxidation zone (104). When the temperature detected by the thermocouple is higher than a preset temperature, the flow rate opening regulating electric valve can regulate the air intake of the air inlet (105).

2. The device for improving the gasification thermal efficiency of a biomass gasifier according to claim 1, characterized in that: Also includes: A dryer is used to reduce or remove moisture in the biomass raw material, and the discharge port (6) of the dryer is connected to the inlet of the gasifier (1).

3. The device for improving the gasification thermal efficiency of a biomass gasifier according to claim 2, characterized in that: The dryer comprises: The drying cylinder (3) is obliquely arranged on the foundation pier (4), the higher end of which is the first end face, the lower end of which is the second end face, the feed port (5) is opened on the first end face, and the discharge port (6) is opened on the second end face, and the drying cylinder (3) is driven to rotate by a driving device; A hot air inlet pipe (7) is arranged on the second end surface and is connected to the drying cylinder (3). The gasifier (1) has an output pipe (2), the output pipe (2) is connected to the pyrolysis zone (102), and is used to output combustible gas with a temperature higher than 300° C. to the boiler. The hot air inlet pipe (7) is connected to the tail gas outlet of the boiler. A hot air outlet pipe (8) is arranged on the first end surface and is connected to the drying cylinder (3).

4. The device for improving the gasification thermal efficiency of a biomass gasifier according to claim 3, characterized in that: The biomass raw material is fed into a feed port (5) via an elevator, and both the elevator and the discharge port (6) are provided with a microwave moisture meter.

5. The device for improving the gasification thermal efficiency of a biomass gasifier according to claim 3, characterized in that: Also includes: An air preheater is connected to the tail gas outlet of the boiler, and is used to heat the air and transport it to the air inlet (105) and / or the hot air inlet pipe (7) of the gasifier (1).

6. The device for improving the gasification thermal efficiency of a biomass gasifier according to claim 1, characterized in that: Also includes: A humidity sensor is arranged in the gasifier (1) and close to the top thereof, and is used to monitor the humidity at the top of the gasifier (1); A cooling circulation system is used to circulate the air in the gasifier (1) and remove moisture from the air when the humidity sensor detects that the humidity at the top of the gasifier (1) is higher than a preset humidity.

7. The device for improving the gasification thermal efficiency of a biomass gasifier according to claim 6, characterized in that: The cooling circulation system comprises: An air inlet pipe (9) is connected to the gasifier (1), and the connection point is close to the top of the gasifier (1); A coil (10) is connected to the air inlet pipe (9) and is coiled on a mounting frame (14), wherein the mounting frame (14) is fixedly mounted on the outer surface of the gasifier (1); A three-way pipe (11), a first end of which is connected to the coil (10) and a second end of which is vertically arranged and used for discharging cooling water and cooling tar in the coil (10); The return air pipeline (12) is connected to the third end of the three-way pipe (11), the return air pipeline (12) is connected to the gasifier (1) and an induced draft fan (13) is provided on the return air pipeline (12).

8. The device for improving the gasification thermal efficiency of a biomass gasifier according to claim 7, characterized in that: The mounting frame (14) is fixedly arranged on the top of the gasifier (1), and the air inlet pipe (9) extends upward and is in communication with the coil (10).

9. The device for improving the gasification thermal efficiency of a biomass gasifier according to claim 1, characterized in that: The gasifier is one of square, round, upper round and lower square, or upper round and lower round.

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