Volumetric continuous biomass gasification apparatus

Abstract

The invention provides a volumetric biomass gasification apparatus that operates continuously and bums the generated biomass gas to generate heat, using organic materials as fuel. The biomass gasification apparatus according to the invention has an L-shaped body, including a fuel feeding chamber, primary air box, reaction chamber, secondary air box, ash discharge unit, and air supply fan.

Description

[0001] VOLUMETRIC CONTINUOUS BIOMASS GASIFICATION APPARATUS

[0002] Technical Field

[0003] The invention is in the field of energy production from biomass, specifically biomass gasification, biomass gasification apparatus, and burning of biomass gas to create heat, wherein the biomass gasification apparatus is a volumetric continuous biomass gasification apparatus.

[0004] Background Art

[0005] Biomass gasification with the goal of effectively creating a source of combustion gas from carbon-based materials, especially plants such as wood, rice straw... following the process of heating fuel in a closed and limited volume of oxygen, at a typical temperature of about 550-6500C (can be up to 12000C) and the amount of oxygen supplied is about 23-30% compared to the amount of oxygen needed to completely bum the fuel. Under these conditions, biomass fuel participates in a series of reactions:

[0006] (1) C + 02 = CO2 + Q (393.5kJ) (exothermic) is a direct combustion reaction

[0007] Note that because carbon makes up the majority of the fuel, the direct carbon combustion reaction (reaction (1) is the main source of heat generation, while the overall effect of the reactions produces synthesis gas (syngas) (2 ), (3), (4), (5) are endothermic.

[0008] The result of this chain of reactions is syngas, a collection of combustible gases including CO (carbon monoxide), H2 (hydrogen), and CH4 (methane), used as fuel for thermal applications. When burning (oxidizing) these gases:

[0009] CO gives a red flame and bums slowly according to the reaction: (6) 2C0 + 02 = 2CO2 + Q (586kJ) (exothermal)

[0010] H2 bums quickly with a colorless flame:

[0011] (7) 2H2 + 02 = 2H2O + Q (483.6kJ) (exothermal)

[0012] CH4 burns quickly with a blue flame:

[0013] (8) CH4 + 202 = C02 + 2H2O + Q (891kJ) (exothermic)

[0014] The successive reaction stages in a typical biomass gasifier can be described as follows: Biomass fuel is piled into a vertical fuel column, air is supplied from below and the fire is ignited from above. When the equipment operates stably (it takes from 2 minutes to 1 hour depending on the type and size of the equipment), the reaction zones begin to clearly form. Biomass fuel participates in the reaction zones in the following order:

[0015] (a) Dehydration: biomass begins to heat up, causing the humidity to decrease to 0 (fuel is dry) and the temperature reaches 150° C. Water vapor, if it enters the pyrolysis and gasification zones, will participate in reactions (2) and (3) above.

[0016] (b) Torrefaction: biomass heated up to 350° C, without any change in chemical composition because it has not participated in the reaction. However, physically, the internal friction of the fuel block has decreased sharply, the fuel is dry on their surface, does not absorb moisture again and is ready to participate in reactions in the pyrolysis and gasification zones.

[0017] (c) Pyrolysis: in this zone, the average temperature is 550 ± 50° C. The series of chemical reactions mentioned above begins to take place here. Initially, the most flammable substances in biomass (volatile substances) such as essential oils and shortchain hydrogen carbides react first, followed by more difficult-to-burn substances, such as sugar, starch, and lignin, partly hemi-cellulose and cellulose. Due to the lack of oxygen, the fixed carbon that forms the 'skeleton' that shapes the unbumed material during this period - mainly cellulose - remains in the form of biochar (also known as biochar), accounts for about 30-35% of the total volume of fuel injected. Thus, the pyrolysis stage converts about 65-70% of biomass into syngas (H2, CO and CH4). (d) Gasification: is the stage of gasification to the most difficult-to-bum fuel, biochar. The temperature of the gasification zone is usually around 600 - 800° C, even up to 1200°C. In the gasification zone, reactions (2), (3), (4) and (5) occur thoroughly, converting biochar, CO2 and steam into synthesis gas (syngas).

[0018] The final part of the gasification stage is sometimes called 'reduction' because it completely converts the biochar to syngas. The solid part of the fuel after burning is only ash and can reduce the original fuel volume by up to 99%. The highlight in this region is that reactions to create syngas do not require oxygen. That's why the thorough gasification process usually only occurs in industrial equipment as a result of the ability to keep the correct oxygen / fuel ratio throughout the reaction process, so that oxygen is only supplied to the pyrolysis zone, but does not go into the gasification zone. In the case of excess oxygen, a direct combustion reaction (complete combustion of syngas and fixed carbon) will occur in the gasification zone, reducing efficiency and reducing the life of the equipment.

[0019] Currently, biomass equipments use the following gasification methods:

[0020] (i) Small appliances that operate in batches (intermittently), mainly serving the needs of residential cooking or small-scale production, are appliances that operate in batches, including two main types: Burning from above air from the bottom (TLUD - Top Lit Up Draft), and bum below the air ventilation from above (BLDD - Bottom Lit Down Draft).

[0021] (ii) Large-scale industrial gasification equipment systems operate continuously, using wood chips or pellets. The syngas produced is used to generate electricity and heat simultaneously. The gasification diagram applied is bottom lit down draft (BLDD - Bottom Lit Down Draft). In continuous equipments, the reaction zones are fixed, while the fuel moves through the reaction zones one after another, and ash, ash and bio char (if any) are drained out.

[0022] The common disadvantages of the technological methods and equipment mentioned above are: (i) complex structure, high manufacturing and operating costs; (ii) selective fuel that be gasified, biomass must have a moisture content below 23%, commonly 10-15%, fuel size must be relatively uniform, creating additional shredding and drying steps; (iii) on a small scale, there is currently no equipment that operates continuously, intermittent equipments have low efficiency, is difficult to use and control; (iv) large equipments require an abundant and continuous fuel supply, which is not suitable for the dispersed nature and low calorific value of biomass.

[0023] Summary of Invention

[0024] The purpose of the invention is to overcome the above-mentioned disadvantages of biomass gasification apparatus.

[0025] To achieve the above purpose, the invention provides a continuously operating volumetric biomass gasification apparatus - VCBG. Specifically, the process of creating syngas and burning off syngas is started by burning fuel from above and supplying air from below ( Top Lit Up Draft -TLUD ) - Startup phase. When the gas process is stable, switch to burning fuel from below and supplying air from the bottom up (Bottom Lit Up Draft - BLUD) through continuous feeding from top to bottom - Stable phase.

[0026] The invention provides a volumetric continuous biomass gasification apparatus with an L-shaped body. This apparatus includes the following parts:

[0027] The box-shaped fuel feeding chamber gradually narrows at the bottom,

[0028] The primary air box is located below the fuel feeding chamber,

[0029] The reaction chamber is located next to the primary air box, located below the fuel feeding chamber and is connected to the fuel feeding chamber so that fuels can move from the fuel feeding chamber into the reaction chamber and perform the gasification process inside it, in which the reaction chamber gradually narrows towards the gas burner,

[0030] The secondary air box is a box-shaped secondary air supply line, arranged from the back of the primary air box, passing through the bottom of the primary air box into the reaction chamber and extending along the bottom surface of the reaction chamber to the gas burner,

[0031] The ash discharger is located just below the reaction chamber,

[0032] The air supply fan is mounted on the body of the fuel feeding chamber ,

[0033] According to the preferred embodiment of the invention, the above gasification apparatus is characterized in that: The fuel feeding chamber has a lid on top to refill fuel and seal the fuel feeding chamber, on the body of the fuel feeding chamber, there is a handle to move the apparatus when necessary.

[0034] The primary air box is in the shape of a closed box, hollow inside, this box is sealed to create an isobaric chamber inside the box; the back side of the primary air box has a primary air inlet made from a box steel pipe. Inside the primary air box and in the center of this box, there is a square steel plate arranged perpendicular to the bottom of the primary air box. The height of this steel plate is higher than the height of the primary air inlet to evenly disperse the primary air blowing into the primary air box; the top surface of the primary air box is tilted 40 °- 50° compared to the vertical; The front side facing the back of the box is structured at an angle of 30° - 40° compared to the vertical and on this side, there are arranged air ventilation holes evenly spaced 3 - 5cm from the outer edge to distribute primary air into the reaction chamber; wherein the back of the primary air box is linked to a steel plate located outside the primary air box so that the primary air box can be fixed to the apparatus using a bolt mechanism at the four corners of the plate.

[0035] The secondary air box has a secondary air supply head located inside the reaction chamber and on the gas burner side, this head is located about 5 - 7 cm from the gas burner mouth of the apparatus.

[0036] According to one embodiment of the invention, the primary air box can be removed from the gasifier by removing the bolts attached to the steel plate mounted on the outside of the primary air box. Therefore, it can be removed from the gasifier, which can facilitate inspection, maintenance and repair when necessary.

[0037] According to one embodiment of the invention, the surface of the secondary air supply head has holes drilled evenly spaced on the surface to distribute the secondary air, the holes located on the outside have a larger diameter than the holes located on the inside.

[0038] According to an embodiment of the invention, in which the ash discharge part is located directly below the reaction chamber, the ash discharge plate includes a flat part and a Z-shaped part, the flat part acts as a block to open and close the connecting ash discharge door connected with the reaction chamber above it and a Z-shaped section that pushes ash out of the apparatus during the ash discharging process; in which the ash discharge plate is welded to the pull rod that moves the ash discharge plate, on the pull rod body is welded an MIO nut to keep the Z-shaped plate moving within a predetermined space.

[0039] According to one embodiment of the invention, the air supply fan is mounted on the body of the fuel feeding chamber. When the fan operates, the vibration force from the fan will help the fuel from the fuel feeding chamber move better to the reaction chamber.

[0040] The air supply fan has an air divider valve attached at its outlet. The air divider valve is designed in the form of a lever, there is a cross-shaped air divider inside it. When removing the lever, the valve will distribute air from the common air supply pipe to the primary air inlet and secondary air inlet, and the air flow to the primary air box and secondary air box can be adjusted.

[0041] In any of the above embodiments, wherein the upper surface and front surface of the primary air box are arranged at an angles inclined relative to the fuel feeding chamber to allow the fuel to automatically fall into the reaction chamber continuously under the influence of gravity and the ash formed from direct combustion will also slide to the bottom of the fuel feed chamber, making it easier to carry out the ash discharging process.

[0042] Advantageous Effects of Invention

[0043] The biomass gasification apparatus and the gasification method according to this invention helps overcome the disadvantages of current plant-based fuels: (i) low energy density, (ii) difficulty in controlling the combustion process and high emissions, (iii) decentralized distribution and not available all year round, (iv) uneven quality due to variety of types and dependence on weather; Therefore, biomass is rarely used in the modem energy basket.

[0044] This apparatus (VCBG) also helps create biochar, which are the unbumed (fixed carbon) and unbumed (minerals) components of the fuel left after gasification. Depending on the demand of the operator, the amount of biochar can range from 0- 35% compared to the initial fuel volume: if syngas is needed, reactions (3), (4 ) and (5) will take place completely, all carbon in the fuel will be converted into syngas; Conversely, if more biochar is desired, these reactions end early and retain the fixed carbon. Biochar is used as a soil enricher and amendment, water filter, and in many agricultural applications.

[0045] During operation, negative pressure at the bottom of the fuel feed hopper and the ash outlet at the bottom of the reaction chamber is formed thanks to a combination of factors including: primary air blowing speed; relative position of the reaction chamber with the fuel feed hopper and gas burner; secondary air speed; The structure suddenly narrows the cross-section of the syngas path creating the Venturi effect; relative position of secondary air box and gas burner; and take advantage of the sudden strong expansion when syngas meets the secondary gas stream and ignites, creating a strong fire stream from the nozzle into the consumer's heat-receiving chamber. This spray stream creates a strong suction force for syngas from the chamber, bum. Due to this negative pressure field, syngas and smoke and heat leakage from the fuel feed port or ash discharge port are avoided, ensuring the equipment operates continuously without interruption.

[0046] The design of the primary air box creates an isobaric chamber, with an optimally calculated air speed to bring the direct combustion zone deep into the center of the fuel mass to create optimal conditions for the VCBG reaction to occur. At the same time, it minimizes the phenomenon of ash adhesion.

[0047] Technical benefits of the gasification apparatus:

[0048] Compact, low initial investment cost but high capacity due to superior capacity / volume ratio compared to traditional gasification.

[0049] Easy to manufacture and maintain due to simple structure, few high heat- resistant parts (only the burner), only the fan and biochar discharge screw are moving parts, but are placed outside the heat-resistant area, so the design VCBG apparatus can be made from low-cost materials, are easy to operate and check, and require little maintenance;

[0050] Fuel requirements are relatively low because VCBG accepts fuels with low homogeneity, low density (up to 70kg / m3), and humidity up to 30%. These properties far exceed the requirements for traditional gasification which requires high homogeneity, an energy density of 120kg / m3 or more and a moisture content of no more than 23% (common is only 15%).

[0051] Continuous operation: The capacity range from 30kW - 500 kW / h meets many different application requirements for heat usage.

[0052] Low emissions and high efficiency thanks to good quality syngas and complete combustion thanks to thorough mixing of the secondary gas - syngas mixture in the mixing chamber. Besides, because the ascent speed of syngas is very slow, it does not carry away solid micro-particles from the fuel, minimizing PM2.5 dust after burning.

[0053] Fuel feeding and unloading are simple and easy: fuel feeding is mainly based on gravity and takes advantage of the internal friction reduction properties of the fuel passing through the torrefaction zone. Discharging biochar and ash relies on the porosity of the coal block and thanks to the continuous flow from top to bottom preventing the clumping of molten ash.

[0054] Increase the ratio of H2 and CH4 in syngas, making the flame bluer and clearer by adding steam to the reaction chamber to promote reactions (3) and (5). In particular, VCBG can also create these reactions right at the Burner thanks to the addition of steam from the dehumidification zone into the mixing chamber.

[0055] High quality biochar: Activated biochar increases porosity about 1.5- 1.8 times (biochar from unactivated rice husk increases from 180 m2 / g to 340 m2 / g after activated, biochar from com cob increased from 528-770 m2 / g).

[0056] The apparatus is easy to control and operate. The power adjustment range is also very wide, from 0-100%, with an adjustment response time of 3-5 seconds. The equipment can be incubated for hours to days, depending on the reaction chamber volume. In case you need to stop the furnace urgently (extinguish the furnace), simply turn off the primary air, maximize the secondary air (to cool the furnace) and inject steam into the reaction chamber to extinguish the fire.

[0057] Brief Description of Drawings

[0058] Figure 1. Perspective drawing of the continuous gasification apparatus (Model S)

[0059] Figure 2: The drawing depicting the structure of the continuous gasification apparatus Figure 3: The drawing depicting the primary air box and its cross-sections

[0060] Figure 4: The drawing depicting the secondary air box and its cross-sections

[0061] Figure 5: The drawing depicting the ash discharge unit and its cross-sections

[0062] Figure 6: The drawing depicting the operating zones of the gasifier and illustrating the path of the gas flows in the gasifier

[0063] Description of Embodiments

[0064] A volumetric continuous biomass gasifier (VCBG) is essentially as shown in Figure 1 with an L-shaped body in the form of a box made of metal or heat-resistant material. The box shape can be a polyhedral box, in which the fuel feeding chamber is arranged vertically and gradually narrows downward, this chamber has a lid at the loading door to load biomass fuel and close the equipment. Below the fuel feed chamber is the reaction chamber, which gradually narrows towards the gas burner (also known as the flame nozzle). The flame nozzle has a horizontal or vertical spray form depending on the different applications of the equipment. Located next to the reaction chamber and immediately below the fuel feeding chamber is the primary air box to supply primary air. The secondary air box is a system of boxes / tubes arranged inside the reaction chamber. Below the reaction chamber is an ash discharger constructed so as to seal the bottom of the reaction chamber in the operating state of the apparatus, and the ash discharger is constructed with the equipment so that it can be slid for discharging ash when the apparatus is in the ash discharging state. The biomass gasifier according to the present invention can be made in such a way that it can be easily moved by means of a four-wheel mechanism arranged at the bottom of the apparatus.

[0065] According to the embodiment as shown in Figure 2, a volumetric continuous biomass gasification apparatus with an L-box shaped body, in which this apparatus includes the following parts:

[0066] The fuel feeding chamber is a box-shaped box that gradually narrows at the bottom,

[0067] Primary air box 2 is located below the fuel feeding chamber, Reaction chamber 4 is arranged next to the primary air box, located below the fuel feeding chamber and connected to the fuel feeding chamber so that fuel can move from the fuel feeding chamber into the reaction chamber and undergo gasification inside it, in which the reaction chamber gradually narrows towards the gas burner.

[0068] Secondary air box 5 is a box-shaped secondary air supply line, arranged from the back of the primary air box, passing through the bottom of the primary air box into the reaction chamber and extending along the bottom surface of the reaction chamber to gas burner.

[0069] Ash discharge unit 3 is located directly below the reaction chamber,

[0070] Air supply fan 7 is mounted on the body of the fuel feeding chamber.

[0071] According to one embodiment, the fuel feeding chamber 1 has a lid on top that can be opened when refueling and the fuel feeding chamber is sealed, on the body of the fuel feeding chamber, there is a handle to move the equipment when needed.

[0072] Primary air box 2, as shown in Figure 3, has a closed box shape, hollow inside. This primary air box is hermetically sealed to create an isobaric chamber inside the box; the back of primary air box 2a has primary air inlet 2b made from box steel pipe to spray primary air into the primary air box. To create isometric characteristics inside the primary air box, inside the primary air box and in the center of this box, there is a 2e steel plate arranged perpendicular to the bottom of the primary air box, the height of this steel plate is higher than the height of the primary air inlet inside the primary air box to evenly disperse the primary air blowing into the primary air box. The upper surface 2c of the primary air box is structured at an angle of 40 °- 50 “compared to the vertical. The 2d front side facing the back of the box is structured at an angle of 30 °- 40 “compared to the vertical and on this side are arranged air vents evenly spaced and 3 - 5cm from the outer edge to distribute primary air into the reaction chamber.

[0073] According to other design options of the invention, the primary air box can be designed as one piece with the gasifier or can be designed in a form that can be removed from the equipment for easy inspection, repair and maintenance when necessary. In the case of a detachable design, the back of the primary air box is linked to a steel plate located outside the primary air box so that the primary air box can be fixed to the equipment using a bolt mechanism at four comers. Secondary air box 5, as shown in Figure 4, has secondary air supply head 5a located inside the reaction chamber and on the gas burner side, this section is located about 5 - 7 cm from the gas burner mouth. The surface of the 5a secondary air supply head has holes drilled evenly spaced on the surface to distribute the secondary air. The holes on the outside have a larger diameter than the holes on the inside. Because it is located inside the reaction chamber, the secondary air is supplied from the air supply fan is heated, which creates favorable conditions for burning syngas at the burner side.

[0074] Figure 5 depicts the ash discharge part, this part is located directly below the reaction chamber, including the ash discharge plate consisting of a flat part and a Z- shaped part, the flat part acts as a block to open and close the ash discharge door connected to the reaction chamber above it and the Z-shaped part push ash out of the apparatus during the ash discharging process; in which the ash discharge plate is welded to the drawbar that moves the ash discharge plate, on the drawbar body is welded an MIO nut to keep the Z-shaped part moving within a predetermined space.

[0075] Air supply fan 7 is mounted on the body of the fuel feeding chamber. When the fan operates, the vibration force from the fan will help the fuel from the fuel feeding chamber move better to the reaction chamber. Air supply fan 7 has an air divider valve 8 installed at its output. The air divider valve is designed in the form of a lever; inside there is a cross-shaped air divider. When moving the lever, it will distribute air from the common supply pipe to the primary air and secondary air inlets, and the air flow to the primary air box and secondary air box can be adjusted.

[0076] According to the invention and according to the above-mentioned embodiments, the upper and front surfaces of the primary air box 2 are arranged at an angle inclined relative to the vertical direction (layout direction of the fuel feeding chamber) allowing fuel to automatically fall into the reaction chamber continuously under the influence of gravity and the ash formed from direct combustion will also slide to the bottom of the fuel feed chamber, making it easier to carry out the ash discharge process.

[0077] Description of the operating principle of the equipment according to the invention When operating, air is blown by the air supply fan through the air divider valve to distribute air into the primary air box and secondary air box. The air divider valve has a lever to adjust the amount of air entering the primary and secondary air box. The primary air is optimally calculated so that the air speed when passing through the primary air holes on the primary air box is from 5 - 10 m / s to bring the burning area directly deep into the center of the fuel block to create conditions for the VCBG reaction to occur optimally, while minimizing the phenomenon of ash adhesion on the surface of the primary air box.

[0078] Air from the primary air box of the VCBG equipment / apparatus passes through the air holes, at high speed, oxygen ignites directly with biomass fuel according to reaction (1), producing CO2 gas and releasing heat. This direct burning zone is only concentrated in the center of the gasifier because this area is supplied with oxygen. Surrounding areas do not have direct burning due to lack of oxygen in those areas. One part of the heat emitted in the direct combustion zone will be pushed up due to thermal convection and inertia of the hot air flow from the surface of the primary air box into the heart of the biomass material. Other part of the heat is transferred to the surrounding direct burning area thanks to heat radiation, leading to the creation of a gasification zone surrounding the direct burning area. Similarly, the pyrolysis zone is formed around the gasification zone, creating a zone structure as shown in Figure 6.

[0079] Accordingly, during operation, three stereoscopic zones are formed that surround each other: direct combustion zone, gasification zone and pyrolysis zone. In the innermost is the direct combustion zone, where reaction (1) takes place, burning carbon to produce heat and CO2. Outside the direct combustion zone is the gasification zone, where reactions (2), (3), (4), (5) to create syngas take place strongly by absorbing heat energy and CO2 from the direct combustion zone. The outermost part is the pyrolysis zone, where volatile substances and flammable substances participate in the reaction chain (2), (3), (4), (5) enriching and increasing the amount of H2 and CH4 in the syngas, at the same time absorbs most of the heat energy that is not used by the gasification zone. The generated syngas will go up the burner without going back into the fuel feeding chamber and biochar discharge port due to the pressure difference created from the Venturi effect at the burner. The secondary air box is located close to the bottom of the reaction chamber and is located inside the reaction chamber. When the apparatus operates, the secondary air is heated when passing through the reaction chamber before going to the gas burner, causing syngas gas after being mixed with secondary gas more flammable.

[0080] The secondary air box is located between the fire nozzle (gas burner) and 5-7 cm away from the flame nozzle, helping to narrow the cross section of the syngas path, combining the air speed from the air hole from the secondary air box to create Venturi suction force at the burner to create negative pressure at the entrance to the fuel feeding chamber, leading to syngas not escaping from the fuel feeding chamber. Creating negative pressure at the bottom of the fuel feed port leads to simplification of the feeding and ash discharge parts while still not causing syngas gas (smoke) to leak into the environment, greatly reducing product costs.

[0081] The negative pressure at the bottom of the fuel feeding chamber (which is the feed section into the reaction chamber) and the ash outlet at the bottom of the reaction chamber are formed by combining many factors: primary air blowing speed, relative position of the reaction chamber with the fuel feed hopper and flame nozzle, the secondary air speed, the narrowing structure of the syngas path section creating the Venturi effect at the burner, the relative position of the secondary air box and the flame nozzle, and taking advantage of the strong expansion when syngas meets the secondary air stream and ignites, creating a strong fire stream from the nozzle into the consumer's heat-receiving chamber. This creates a strong suction force for syngas from the combustion chamber. Due to this negative pressure field, syngas and smoke and heat leakage from the fuel feed port or ash discharge port are avoided, ensuring the equipment operates continuously without interruption.

[0082] Ash discharge process

[0083] Biomass fuel will be continuously supplied into the fuel feeding chamber. Then it will automatically fall into the gas generation chamber due to the effect of gravity without any other external force. After burning, ash will be discharged through the ash outlet during the operation of apparatus.

[0084] Detailed description of the actual operating process of the continuous gasification equipment - VCBG (Model S) according to the invention. Lighting process'. Put flammable fuels such as wood chips, com husks, straw, and dry leaves into the reaction chamber (accounting for about 50% of the chamber volume). Next, feed regular fuel (pellets, wood chips,...) into the fuel feed hopper and let the fuel flow to fill the remaining volume of the reaction chamber (as well as filling the fuel feed hopper). Then light the stove through the fuel feeding chamber. When the fire has ignited the fuel in the reaction chamber, close the lid. After 1-2 minutes the lighting process will end and the equipment will switch to normal VCBG operation.

[0085] Normal operating stage

[0086] The direct combustion zone is formed and expands from the top and front sides of the primary air box; extending deep inside the mass due to the high primary air velocity blowing from the primary air box, then to the gasification zone, the pyrolysis zone is in the form of spherical regions surrounding each other. The torrefaction zone and dehumidification zone are also formed respectively. The size of these zones depends on the amount of primary air input: when large capacity is needed, adjust the air divider valve to increase the primary air flow, the reaction zones expand and the torrefaction zone is pushed upward; on the contrary, when it is necessary to reduce equipment capacity, the primary air flow will be reduced, the reaction areas will narrow towards the center of the reaction chamber. The torrefaction zone lowers and surrounds the pyrolysis zone.

[0087] In steady state, the highest temperature in the fuel block core is up to about 1200 ± 1000C and gradually decreases to the periphery (adjacent to the reaction chamber shell) - to about 3500C. The part above the pyrolysis zone is the torrefaction zone and the dehumidification zone, with the temperature gradually decreasing from bottom to top, from inside to outside. The temperature at the outer edge of the dehumidification zone is close to the outside ambient temperature.

[0088] When the syngas rises from the material layer surface, it will move towards the burner due to the lower pressure in the burner area because of the Venturi effect at the burner. Preventing syngas from going back up the fuel feed port or leaking through the ash discharge port. Syngas approaches the fire vent. Here, syngas is mixed with air and ignited. Due to the narrow design at the gas burner, the secondary air moves quickly and is sucked in and mixed with the syngas. The main reason why small gasifiers cannot operate continuously is because they cannot create negative pressure in the fuel feeding area.

[0089] Leaving out the mixing zone, the combustion gas mixture enters the combustion area of the burner and ignites. Due to careful mixing, the mixture bums thoroughly with no soot or tar left. It should be noted that the burning area at the burner has been formed from the start-up phase and continues continuously into the steady stage.

[0090] The biochar discharge unit is installed at the bottom edge of the reaction chamber, with the following integrated functions:

[0091] Discharging biochar: In case of the operator wants to have biochar, as soon as the equipment enters the steady stage, pull the lever to let the ash fall into the ash chamber, push the lever back to push the biochar out and increases the fuel supply rate into the reaction chamber.

[0092] Application of continuously operating volumetric biomass gasification apparatus - (VCBG Equipment)

[0093] VCBG equipment allows the diverse use of many different plant fuel sources such as wood, straw, branches, leaves, rice husks ...). Using this equipment brings great benefits in that equipment investment costs, fuel costs and operating costs are low, easy to operate and use, allowing raw materials for biomass to be processed at the site.

[0094] Below is a table comparing the cost (economic efficiency) of using biomass fuel with VCBG gasification equipment according to the invention, compared to common fuels in industry: coal, DO oil and Liquefied petroleum gas (LPG) in useful heat equivalents.

[0095] *4200 kCal / kg is the average calorific value of biomass;

[0096] **1 kg of biomass is considered a standard comparison value (equivalent to 80% x 4,200=3,360 kCal);

[0097] *** The average production cost of biomass fuel used for VCBG is 600 VND / kg, while the estimated commercial value is 1,500 VND / kg;

[0098] **** The energy cost of biomass is comparable to coal, DO oil and LPG for the same useful thermal energy equivalent.

[0099] It can be seen that the cost of biomass energy using VCBG is only 46% coal, 22% DO and 23% LPG, creating a great economic motivation for converting to biomass.

[0100] The cost of on-site biomass fuel production is low and universal shredding and screening equipment can be used because VCBG does not require strict fuel requirements. Raw fuels in the form of bars, lumps, branches, and nodes can be fed into the reaction chamber along with fine fuels in powder or small granular form. Biomass types with low energy density such as rolled straw, peanut shells, cassava stalks, com stalks, tree bark... can all be used well, while these types of biomass are not currently considered fuels and has almost no commercial value. While conventional gasification requires an average moisture content of 15% and a maximum of 23%, VCBG works well in the 25-30% range. Due to that, VCBG reduces fuel treatment and storage costs and expands potential biomass reserves.

[0101] VCBG has great potential to contribute to combating climate change through mechanisms, because it not only helps gradually replace fossil fuels, but also replaces them effectively, because it helps reduce C02 emissions, better than with previous gasification methods.

[0102] Reduce greenhouse gas emissions by burying carbon through biochar. In the case of a VCBG equipment that combines both heat generation (syngas) and biochar functions, the coal output is 25% of the input dry mass. The carbon content in VCBG biochar is 80%. Thus, with 1 ton of dry biomass fuel, VCBG creates 250 kg of biochar and buries 733 kg of CO2.

[0103] VCBG completely converts solid fuel to gas before burning, thereby eliminating the amount of black and brown carbon caused by direct biomass combustion. Black and brown carbon are aerosols suspended in the air caused by incomplete combustion of solid fuels. These aerosols stay in the atmosphere for an average of 3 weeks, then fall to the ground with precipitation. During that time, they absorb solar radiation energy and create a greenhouse effect similar to CO2 and other greenhouse gases.

[0104] Applications of VCBG model S

[0105] Due to its flexible characteristics and wide power range, VCBG performs well in many applications that require heat energy in all areas of life.

[0106] Two typical invention implementation cases are stoves for urban cooking and industrial boilers. a) Cookstoves for urban areas applying VCBG allow saving cooking costs of at least 30%; b) Industrial boilers applying VCBG allow: (i) Reduce equipment costs throughout the life cycle, including initial investment, fuel costs, and maintenance; (ii) flexibility in using local fuel in terms of quality and quantity; (iii) the ability to utilize biochar. There is a similar correlation with boilers using LPG, coal and DO. However, it should be noted that the number of boilers using PLG is very small, and boilers using DO are not common, but are mainly found in coal-fired boilers and direct-fired biomass boilers.

[0107] Industrial Applicability

[0108] The apparatus according to the invention can be made in the compact structure, low initial investment cost but high capacity due to superior capacity / volume ratio compared to traditional gasification.

[0109] It can be easy to manufacture and maintain due to simple structure, few high heat-resistant parts (only the burner), only the fan and biochar discharge screw are moving parts, but are placed outside the heat-resistant area, so the design VCBG apparatus can be made from low-cost materials, are easy to operate and check, and require little maintenance;

[0110] Fuel requirements are relatively low because VCBG accepts fuels with low homogeneity, low density (up to 70kg / m3), and humidity up to 30%. These properties far exceed the requirements for traditional gasification which requires high homogeneity, an energy density of 120kg / m3 or more and a moisture content of no more than 23% (common is only 15%). Reference Signs List

[0111] 1. fuel feeding chamber

[0112] 2: primary air box

[0113] 2a: back side

[0114] 2b: primary air inlet

[0115] 2c: upper surface

[0116] 2d: front side

[0117] 2e: square steel plate

[0118] 3 : ash discharger

[0119] 3a: ash discharge plate

[0120] 3b. front plate

[0121] 3c. the push rod

[0122] 3d: ash tray

[0123] 4: reaction chamber

[0124] 5: secondary air box

[0125] 5 a: secondary air supply head

[0126] 6: gas burner

[0127] 7 : air supply fan

[0128] 8: air divider valve

[0129] Syngas path

[0130] Secondary air path

[0131] Primary air path

[0132] Flow of gases moving in the fuel feeding chamber.

Claims

Claims1. A continuous volumetric biomass gasification apparatus with an L-shaped body, the apparatus comprising: a fuel feeding chamber (1) box-shaped gradually narrowing at the bottom, a primary air box (2) is located below the fuel feeding chamber, a reaction chamber (4) is arranged next to the primary air box, located below the fuel feeding chamber and is connected to the fuel feeding chamber so that fuel can move from the fuel feeding chamber into the reaction chamber and perform the gasification process within it, in which the reaction chamber gradually narrows towards the gas burner, a secondary air box (5) is a box-shaped secondary air supply line, arranged from the back of the primary air box, passing through the bottom of the primary air box into the reaction chamber and extending along the bottom surface of the reaction chamber to the gas burner, the secondary air supply head (5a) is arranged on the gas burner side of the apparatus, the ash discharger (3) is located just below the reaction chamber, the air supply fan (7) is mounted on the body of the fuel feeding chamber , characterized in that: the fuel feeding chamber (1) has a lid on top to fill fuel and close the fuel feeding chamber, on the body of the fuel feeding chamber there is a handle to move the apparatus when necessary, the primary air box (2) is in the shape of a closed box, hollow inside, this box is sealed to create an isobaric chamber inside the box; the back side (2a) of the primary air box has a primary air inlet (2b) made from box steel pipe, inside the primary air box and in the center of this box is a square steel plate (2e) which arranged perpendicular to the bottom of the primary air box, the height of this steel plate is higher than the height of the primary air inlet to evenly disperse the primary air blowing into the primary air box; the upper surface (2c) of the primary air box is tilted 40° - 50 compared to the vertical; the front side (2d) facing the back of the box is structured at an angle of 30° - 40° compared to the vertical and on this side arranged air vents evenly spaced and 3 - 5 cm from the outer edge to distribute primary air intothe reaction chamber; wherein the back of the primary air box is linked to a steel plate located outside the primary air box so that the primary air box can be fixed to the apparatus using a bolt mechanism at the four comers, the secondary air box (5) has a secondary air supply head (5a) located inside the reaction chamber and on the gas burner side, this head is located about 5 - 7 cm from the gas burner mouth.

2. The apparatus according to claim 1, wherein the primary air box (2) is removable from the gasification apparatus by removing the bolts attached to the steel plate mounted on the outside of the primary air box.

3. The apparatus according to claim 1 or 2, wherein the primary air box (2) can be removed from the gasification apparatus to facilitate maintenance and repair when necessary.

4. The apparatus according to claim 1, wherein the surface of the secondary air supply head (5a) has holes drilled evenly spaced on its surface to distribute the secondary air, the holes located on the outside having a larger diameter than the holes on the inside.

5. The apparatus according to claim 1, wherein the ash discharge part is located immediately below the reaction chamber, wherein the ash discharge plate (3a) includes a flat part and a Z-shaped part, the flat part serving as an opening and closing stop plate the ash outlet is connected to the reaction chamber above it and the Z- shaped part pushes the ash out of the apparatus during the ash discharge process; in which the ash discharge plate is welded to the push rod (3c) that moves the ash discharge plate, on the pull rod body is welded an MIO nut to keep the Z-shaped plate moving within a predetermined space.

6. The apparatus according to claim 1, wherein the air supply fan (7) is mounted on the body of the fuel feeding chamber, when the fan operates, the vibration force from the fan will help the fuel from the fuel feeding chamber moves better to the reaction chamber.

7. The apparatus according to claim 6, wherein the air supply fan (7) has an air divider valve (8) installed at its outlet, the air divider valve is designed in the form of a lever, there is a cross-shaped air divider inside it, when removing the lever, the valve it will distribute air from the common supply pipe to the primary air inlet and secondary airinlet, and the air flow rate into the primary air box and secondary air box can be adjusted.

8. The apparatus according to any of the foregoing claims, wherein the upper surface and front surface of the primary air box (2) are arranged at an angle relative to the fuel feeding chamber allowing fuel to automatically fall into the chamber reaction under the influence of gravity and ash formed from direct combustion will also slide to the bottom of the fuel feeding chamber, making it easier to carry out the ash discharging process.

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