Device for reforming synthesis gas generated by biomass pyrolysis gasification without pressurization

Abstract

A device for reforming synthesis gas generated by biomass pyrolysis gasification without pressurization generates hydrogen-rich gas from cellulose-rich biomass through non-pressure conversion, and is suitable for methanol production. Pyrolysis and carbon gasification are carried out in separate gasification chambers, and a mixed gas of superheated steam and oxygen can produce a synthetic feed gas (14) containing a small amount of inert gas. The synthetic feed gas (14) is heated to 1300 DEG C in the multiple high-temperature gas-gas silicon carbide tube heat exchanger. The heat exchange is carried out by means of silicon carbide heat exchange tubes (23) which are placed contiguously adjacent to each other. At the temperature of 1000 DEG C or above, the vortex generator (25) can strengthen the conversion reaction, and the generated centrifugal force is 35000 times of the self weight of the gas particles. Since the high temperature heat exchanger allows process heat to be recirculated at a high temperature level, only minimal heat loss occurs. Straw ash is unmelted and is suitable for use as a fertilizer.

Description

Technical Field

[0001] This invention belongs to the field of biomass energy conversion technology. Its purpose is to produce hydrogen-rich gas from cellulose-rich biomass fuels, especially whole bales of straw. The produced gas is suitable for methanol synthesis or hydrogen extraction. The gasified syngas is convectively heated to over 1000°C and then reformed without pressure under a strong airflow. Multiple high-temperature heat exchanges return the heat generated throughout the process to the system. The ash produced will be returned to the fields as fertilizer. Background Technology

[0002] To date, the production of hydrogen-rich gas from biomass requires a temperature of at least 1150℃ and a pressure of 4-11MPa. However, it is difficult to continuously introduce bulk materials or even whole bags of straw into a pressure reactor and achieve a closed process. The molten ash residue taken out from the pressure reactor will be severely devalued whether used as fertilizer or building material.

[0003] This is why straw must be ground before producing hydrogen-rich gas from biomass. However, due to the fiber structure, moisture content, and soil content of straw, the energy required to grind the straw makes the entire process of producing hydrogen-rich gas uneconomical.

[0004] For example, according to DE102005006305A1, the process of producing hydrogen-rich gas from straw involves first pyrolyzing the straw to obtain coke, grinding it, and then forming a pumpable slurry that is forced into a high-pressure, high-temperature gasification reactor. This process places extremely high demands on the pump. In the reactor, the gas temperature must be raised to over 1150°C through internal combustion to achieve rapid high-temperature gasification and conversion. This results in a CO2 content of approximately 30%, making the conversion reaction very slow. Since no methods have been found to enhance this reaction process through gas flow or other technological approaches, the only current option is to apply high pressure. However, because hydrogen production involves the cracking of hydrocarbons and water, high pressure itself would be counterproductive. Removing CO2 before methanol synthesis also causes wastewater pollution and energy loss, as the synthesis gas needs to be reheated afterward.

[0005] Currently, there is no device that can completely return the heat to the pyrolysis reaction. If the waste heat from the pyrolysis gasification reaction needs to be consumed by external users, the site selection of biomass syngas production projects will be affected, and the transportation of straw for syngas may be further away, which contradicts the principle of distributed utilization of straw.

[0006] If ash cannot be effectively separated from biomass coke, many low-melting-point minerals will melt and be contained in the syngas when the ash is gasified with the above slurry at a temperature of 1150°C. This not only causes the loss of the fertilizer value of these minerals, but also brings additional burdens such as coking, heat exchange surface corrosion, or syngas purification due to changes in flue gas temperature.

[0007] The minerals in straw can only be returned to the field by gasifying at a low speed below 400℃ to avoid high-temperature melting. However, it is difficult to compress the gasified gas containing a large amount of tar, acid vapor, soot and dust to 4MPa or higher pressure and introduce it into the high-pressure reactor using conventional compressors.

[0008] The non-pressurized gas reforming process of this invention requires higher quality syngas with lower contents of tar, acid vapor, soot and dust. This non-pressurized gas reforming process can only be achieved by external heating. For cost control reasons, only a convection heat exchanger can best achieve this. However, there is currently no gas-to-gas convection heat exchanger that can operate continuously at 1600°C.

[0009] The industrial hot hydrogen tubular reformer can withstand a high temperature of 930℃, which cannot effectively meet the temperature requirements of biomass reforming into syngas. Therefore, when the industrial hot hydrogen tubular reformer is used for biomass syngas reforming, the pressure needs to be increased to above 11MPa. However, heat exchangers made of ceramic high-temperature resistant materials cannot be used at such pressures.

[0010] While discontinuous heat exchange processes may meet the high-temperature requirements of syngas reforming, they cannot ensure stable reforming temperatures or achieve sufficient gas separation. The cavity jet effect, similar to that of wind turbines, can accelerate the cracking of fluids, especially liquids, but its application in gas conversion at extremely high temperatures is currently unknown.

[0011] Currently, there is no known high-temperature gas-to-gas heat exchanger that operates continuously at 1600℃ and allows heat exchange between one gas and several other gases simultaneously. When biomass pyrolysis coke is used to produce syngas, although burning hydrogen-rich pyrolysis gas can meet the heating requirements, it is impossible to achieve a high hydrogen content in the syngas.

[0012] Currently known technologies cannot achieve a CO:H2 ratio of 1:2 or higher in biomass syngas or reformed gas. To achieve this ratio, either the CO content in the syngas or reformed gas needs to be reduced, or hydrogen from other sources needs to be added to the syngas or reformed gas. Summary of the Invention

[0013] The objective of this invention is to produce a gas with a hydrogen content exceeding 55%, suitable for methanol synthesis or hydrogen purification, from biomass, particularly whole bales of straw, through unpressurized gas reforming. The high pressure of other devices is replaced by other processes in this invention's apparatus, and the low temperature and long-term gasification in this apparatus aim to preserve the value of straw ash as fertilizer. The dust content and inert gas content of the process product gas of this invention do not require gas purging, and the hydrogen from the biomass enters the synthesis gas as hydrogen gas. Through high-temperature heat recirculation, the primary energy utilization rate of this invention's apparatus is over 94%.

[0014] The biomass in this invention includes whole bags of crop stalks, cotton stalks, chopped straw, mushroom cultivation bags, and shredded energy crops, etc. First, the biomass is dried to a moisture content of approximately 5% and a temperature of approximately 50°C. This makes it possible to introduce high-temperature superheated steam into the biomass during subsequent biomass gasification. The process heat returned under high-temperature conditions can save fuel, reduce the combustion process, and activate the surface reactivity of the biomass particles.

[0015] In this invention, the heating, conversion, and cooling of the syngas are all carried out in a multi-stage high-temperature heat exchanger composed of silicon carbide heat exchange tubes. Part of the waste heat generated by this heat exchanger can be used in a straw bale drying module to dry the straw bales. The silicon carbide heat exchange tubes are interconnected via connecting sleeves, with a certain distance between the tubes in the connecting sleeves to form free space. The syngas continuously flows through multiple silicon carbide heat exchange tubes, and a turbulence-splitting edge is formed at the end of each silicon carbide heat exchange tube. The flue gas experiences turbulence at the turbulence-splitting edge, generating pressure pulses that can improve the gas conversion rate.

[0016] The raw material synthesis gas enters the silicon carbide heat exchanger tube in a vortex rotation manner. The inner diameter of the silicon carbide heat exchanger tube is designed to ensure that the centrifugal force acting on 1 gram of gas particles reaches 350 N. The raw material synthesis gas in the silicon carbide heat exchanger tube is convectively heated to at least 1150°C and has a flow velocity of at least 85 m / s by the heating gas outside the silicon carbide heat exchanger tube.

[0017] The number of ions in the syngas containing water vapor increases with temperature and begins to ionize at 1000℃. The water vapor in the syngas enters the plasma state at 1050℃, at which point the bonding force of water molecules weakens. The current and charge generated in the vortex-rotating airflow in the Earth's magnetic field interact with water molecules with dipole structures and generate energy that can counteract the bonding force of water molecules, thus triggering widespread dissociation of water molecules. The hydrogen and oxygen ions released in this way are highly reactive and can undergo intensive conversion without pressure.

[0018] The apparatus of this invention comprises a pre-positioned biomass pyrolysis chamber and a post-positioned biomass gasification chamber, wherein the biomass gasification chamber can send a level signal at any time to adjust the fuel feed rate. According to this invention, the gasification process produces gasified gas with low CO2 content, nitrogen content below 3%, and high soot and tar content. Biomass fuel is continuously fed into the biomass pyrolysis chamber to form a closed fuel layer at least 1.2 meters high, while in the biomass gasification chamber, a fuel layer at least 0.9 meters high is maintained. Water vapor and oxygen are blown into the fuel layer from below the biomass pyrolysis chamber and the biomass gasification chamber, maintaining close contact with the carbon or unburned biomass for more than 3 seconds.

[0019] In the steam introduction zone of the biomass pyrolysis chamber, steam at a temperature of at least 850°C is first blown in, and the surface of the large biomass particles is completely dried and heated to 600°C. Then, a mixture of superheated steam and oxygen is blown in the superheated steam and oxygen mixture introduction zone. Because the blown-in superheated steam or superheated steam and oxygen mixture stays in the fuel bed for a long time, the surface of the large biomass particles can only react with a small amount of oxygen and produce almost only CO without producing CO2.

[0020] During this process, carbon in the soot and tar vapors combines with oxygen molecules, especially oxygen molecules from water splitting, which allows hydrogen ions to combine freely to generate more hydrogen (H2).

[0021] To obtain higher quality syngas, biomass pyrolysis and biomass gasification are carried out successively in two spaces. To prevent the formation of free space during fuel gasification in the fuel bed and the intrusion of oxygen-rich gas, the straw in the biomass pyrolysis chamber is pyrolyzed while being pushed upwards. Under the action of gravity, the biomass is always in a compacted state along the upward direction, so the gas always maintains close contact with the solid biomass.

[0022] To achieve a stable compacted state of biomass in the biomass gasification chamber, the bottom plate of the chamber can be designed at a 33-degree angle to the horizontal. Here, the biomass slides down under its own weight, preventing the creation of free space. For this purpose, the fuel layer in the biomass gasification chamber is maintained at a thickness of more than 0.9 meters, and the gas continuously changes its flow direction between the biomass particles in the fuel layer and repeatedly contacts the biomass surface.

[0023] In conventional biomass pyrolysis and gasification processes, as the biomass mass decreases, the contact between gas and fuel also decreases, leading to an increase in gasification temperature and the production of more CO2. However, according to this invention, the volatiles of the biomass entering the pyrolysis and gasification chambers are released as syngas through pyrolysis and gasification. The volatiles released during pyrolysis and gasification account for approximately two-thirds of the total biomass weight. The remaining biomass residue, approximately one-third of the total feed biomass weight, after the volatiles are released during gasification, is transferred from the biomass gasification chamber to a low-temperature moving grate combustion chamber, thus preventing the production of more CO2 in the biomass gasification chamber. The syngas released from the pyrolysis and gasification processes in the biomass pyrolysis and gasification chambers contains almost all the hydrogen from the biomass feedstock; calculations show that the hydrogen content of the released syngas can exceed 21%.

[0024] The biomass gasification residue transferred to the low-temperature moving grate combustion chamber mainly consists of ungasified carbon fibers, biochar, ash, and soil. The structural design of the low-temperature moving grate combustion chamber enables the long-term and complete low-temperature combustion of these biomass residues. According to the present invention, biomass undergoes pyrolysis, gasification, and combustion in three continuous spaces, making it possible to optimize the three processes and parameters of pyrolysis, gasification, and combustion separately.

[0025] The speed at which the ungasified biomass residue is transferred out of the biomass gasification chamber is regulated by a water-cooled feed roller, thereby forming an almost uniform residue layer in the low-temperature moving grate combustion chamber, which is sealed on top by a refractory ceramic rotatable sealing plate.

[0026] To prevent gas convection between the low-temperature moving grate combustion chamber and the biomass gasification chamber, the pressure in the low-temperature moving grate combustion chamber and the biomass gasification chamber is automatically adjusted to the same set value.

[0027] To prevent air from entering the biomass pyrolysis chamber, the biomass must pass through a fuel gate and a sealed channel located between the fuel drying module and the biomass pyrolysis chamber before entering the chamber. Below the superheated steam inlet area of ​​the biomass pyrolysis chamber, superheated steam at a temperature of not less than 850°C, preferably 900°C, is first blown in at a rate of approximately 6-9% (3% moisture) of the feed biomass mass.

[0028] Then, a mixture of 900°C superheated steam and oxygen with a mixing ratio of 2-2.5:1 is blown into the superheated steam and oxygen mixture introduction zone. The amount blown in is approximately 18-23% of the biomass (3% moisture) of the biomass fed in.

[0029] The biomass in the biomass pyrolysis chamber is heated to about 380-430°C, and about one-third of the biomass mass fed into the biomass pyrolysis chamber is pyrolyzed.

[0030] The biomass then enters the biomass gasification chamber for carbon gasification. To reach the temperature required for carbon gasification, a mixture of superheated steam and oxygen at a temperature of at least 850°C (preferably 900°C) with an oxygen content of 1-4% is introduced. The amount of superheated steam and oxygen mixture introduced is 85-100% of the biomass mass entering the biomass gasification chamber, and the amount introduced can be adjusted according to the temperature of the biomass gasification chamber.

[0031] During the carbon gasification process, a mixture of superheated steam and oxygen at at least 850°C, preferably 900°C, heats the biomass from 420-450°C to 700-740°C and produces CO and H2.

[0032] C + H₂O → CO + H₂ (-151.5 kJ / mol)

[0033] All the gas flows upward at a low speed within the biomass fuel layer. During the gas flow, small dust particles can be moved but almost no dust is carried away, resulting in almost no deposits in the downstream channels and heat exchange surfaces.

[0034] Synthesis feed gas from the biomass pyrolysis chamber and biomass gasification chamber is released at approximately 500-560°C into a multi-stage high-temperature gas-to-gas silicon carbide tube heat exchanger composed of silicon carbide tube bundles for reforming.

[0035] High-temperature heat exchange occurs in short, interconnected, continuous silicon carbide heat exchange tubes, which form a continuous tube bundle. Synthesis feed gas flows within the silicon carbide heat exchange tubes, and heating gas with an initial temperature of 1550°C flows past the outside of the silicon carbide heat exchange tubes, heating the synthesis gas within the tubes to at least 1150°C, preferably to 1300°C, for reforming the pyrolysis and gasification of the synthesis feed gas.

[0036] To overcome thermal expansion, the silicon carbide tube bundle consists of numerous silicon carbide tube segments interconnected by silicon carbide connecting sleeves inserted into a high-temperature resistant concrete partition wall. These connecting sleeves are securely attached to the ends of the silicon carbide tubes, and the ends of the tube segments are sealed by wrapping ceramic fibers impregnated with graphite paste. In this way, each silicon carbide heat exchange tube is locked to one side of the high-temperature resistant concrete partition wall, while the other end can slide within the wrapped ceramic fibers to overcome thermal expansion displacement.

[0037] In the silicon carbide connecting sleeve, a free space is formed between the two silicon carbide heat exchange tubes, with a distance of about 1-3 times the wall thickness of the silicon carbide heat exchange tube. The airflow flowing through this free space and the turbulence splitting edge of the silicon carbide heat exchange tube will be turbulent and generate a vacuum similar to the void jet effect, forming extreme turbulence with pressure pulses. Water molecules that are at high temperature and whose H0 bond force has been weakened will break down.

[0038] Although such water molecule splitting is limited to the vicinity of the turbulent flow splitting edge, the synthesis feed gas undergoes water molecule splitting many times during reforming as it flows through a long multi-stage high-temperature gas-to-gas silicon carbide tube heat exchanger.

[0039] The high-temperature resistant partition wall of the multiple high-temperature gas-to-gas silicon carbide tube heat exchanger in the device of the present invention is a flexible expansion plate made of ceramic fiber. Under the premise of overcoming the expansion forces in the horizontal and vertical directions, the silicon carbide tube heat exchanger in the device of the present invention can be designed to any length.

[0040] The heat energy in the reformed synthesis feed gas acts on the unpressurized steam at a temperature of up to 1300℃, heating the unpressurized steam to a maximum temperature of 900℃, and heating the combustion air and synthesis feed gas together to 600℃.

[0041] The multi-stage high-temperature gas-to-gas silicon carbide tube heat exchanger of this invention recycles almost all of the process heat and applies it to the process of this invention, which is why the device of this invention has high energy efficiency.

[0042] Except for the exhaust gas at about 50°C discharged at the end of the system, the heat energy in the heating gas after the synthesis raw material gas reforming in the device of the present invention is almost entirely recycled for air preheating, water heating, steam heating or biomass drying, and the thermal efficiency of the primary energy of the system is over 94%.

[0043] The corrosion-resistant silicon carbide tubes can withstand temperatures up to 1600℃, so the input and output quantities of the synthesis raw material gas can be freely set, and direct or countercurrent heat exchange can be freely selected.

[0044] Synthetic feed gas is drawn in under negative pressure by a fan. The heat exchange for synthetic feed gas reforming consists of two parts: an initial heat exchange unit and a main heat exchange unit. In the initial heat exchange unit, the synthetic feed gas is heated from 550°C to about 1000°C. In the main heat exchange unit, the temperature of the synthetic feed gas is further increased to over 1150°C, preferably reaching 1300°C.

[0045] The initial heat exchange unit and the main heat exchange unit of the synthesis gas reforming are interconnected via a heat-resistant ceramic transition channel. Synthesis gas heated to 1000°C is accelerated by a vortex generator and rotates before entering the main heat exchange unit, thus triggering a so-called physical effect. The dynamic pressure generated in this way compensates for insufficient static pressure and enhances the heat transfer capacity of the inner wall of the silicon carbide heat exchange tube.

[0046] Because the multiple high-temperature gas-to-gas silicon carbide tube heat exchangers in the device of this invention operate only under negative pressure, high-temperature resistant ceramic materials can be used during the design and construction process. These materials have high compressive strength but are not suitable for tensile loads caused by internal pressure; negative pressure operation can maximize the compressive strength of the materials and tolerate leakage within permissible limits. Attached Figure Description

[0047] Figure 1 A simplified side view of a system utilizing the present invention is shown.

[0048] Figure 2 A schematic diagram of a system for reforming biomass syngas is shown.

[0049] Figure 3 A cross-sectional view of a multi-stage high-temperature gas-to-gas silicon carbide tube heat exchanger is shown.

[0050] Figure 4 A partial plan view of a multi-stage high-temperature gas-to-gas silicon carbide tube heat exchanger is shown.

[0051] Figure 5 The connection of the silicon carbide heat exchange tube in the connecting sleeve of the high-temperature resistant partition wall is shown.

[0052] Figure 6 An eddy current generator made of silicon carbide tubes is shown.

[0053] In the diagram: 1-Biomass pyrolysis chamber, 2-Square bale straw, 3-Superheated steam and oxygen supply chamber, 4-Low-temperature moving grate combustion chamber, 5-Touch sensor, 6-Synthetic feed gas release channel, 7-Flue gas mixing channel, 8-Straw bale drying module, 9-Pushing device, 10-Superheated steam, 11-Oxygen, 12-Sealed channel, 13-Superheated steam introduction zone, 14-Synthetic feed gas, 15-Superheated steam and oxygen mixture introduction zone, 16-Biomass gasification chamber, 17-Water-cooled conveying roller, 18-Rotable sealing plate, 19-Flue gas vortex burner, 20-Variable flue gas nozzle, 21-High-temperature combustion air, 22-1550℃ heated flue gas, 23-Silicon carbide heat exchanger tube, 24-Heat-resistant ceramic transition channel, 25-Vortex generator, 26-High-temperature resistant partition wall, 27-Pressure reducer, 28-High-temperature fan, 29-Fresh air. 30 - Initial heat exchange unit for syngas reforming; 31 - Main heat exchange unit for syngas reforming; 32 - Superheated steam heat exchange unit; 33 - Combustion air preheating unit; 34 - Reformed syngas after dust removal; 35 - High-pressure blower; 36 - Second induced draft fan; 37 - Dust collector; 38 - Steam generator; 39 - Dry gas; 40 - Blower; 41 - Load-bearing wall; 42 - Insulation layer; 43 - Equipment foundation; 44 - Bearing... 45-Ceramic fiber insulation layer, 46-Load-bearing steel plate, 47-Bracket, 48-Fixing hook, 49-Insulation layer, 50-Refractory concrete, 51-Hot air, 52-Expansion board, 53-Pouring template, 54-Ceramic fiber, 55-Silicon carbide connecting sleeve, 56-Adhesive bonding, 57-Turbulence diversion edge, 58-Groove, 59-Cap, 60-Material bag gate, 61-Pouring sealing plate, 62-Unpressurized steam. Detailed Implementation

[0054] This example is designed for the production and reforming of syngas from 1.2 x 1.3 x 2.4 meter square bags of straw (2). The example system feeds in 7 square bags of straw with a moisture content of approximately 30% and a weight of approximately 820 kg per hour. The biomass pyrolysis chamber (1) and biomass gasification chamber (16) can accommodate approximately 8.5 square bags of straw for pyrolysis and gasification for approximately 73 minutes, producing approximately 9000 Nm³. 3 / h synthesis gas.

[0055] Figure 1 The system features an inclined biomass pyrolysis chamber (1) and an inclined biomass gasification chamber (16). The square-bag straw (2) is pushed by a pusher (9) and runs perpendicular to the direction of travel on the conveyor belt, passing through the sealed channel (12) of the bag gate (60) into the biomass pyrolysis chamber (1). During pyrolysis, the square-bag straw (2) remains compacted, ensuring close contact between the gas and the straw.

[0056] After leaving the straw drying module (8), the square-shaped straw (2) with a moisture content of less than 3% and a temperature of about 50°C enters the biomass pyrolysis chamber (1). First, superheated steam (10) at about 900°C is blown in at a speed of about 320 kg / h through the superheated steam introduction zone (13) located at the bottom, heating the bottom layer of the square-shaped straw (2) to a reaction temperature of 600°C. Then, a mixture of superheated steam (10) at 900°C and oxygen (11) (0-20°C) at a pressure of 200-800 Pa is blown in at a speed of 810 kg / h through the superheated steam and oxygen mixture introduction zone (15) located at the bottom.

[0057] As the square-shaped straw (2) leaves the biomass pyrolysis chamber (1) and falls into the biomass gasification chamber (16) at an angle of about 35 degrees, although the shape of the square-shaped straw (2) and the straw gradually lose their mechanical strength as they are gasified, there is always a 90cm thick fuel layer in the biomass gasification chamber (16). The cavity when the biomass slides downward can still be sealed or compacted by its own weight. The time for the mixture of superheated steam (10) and oxygen (11) to pass through the biomass fuel layer may be as long as 3-4 seconds.

[0058] A mixture of approximately 2750 kg / h of 900°C superheated steam (10) and approximately 60 kg / h of oxygen (11) blown into the biomass gasification chamber (16) participates in the gasification of the biomass. The heat of the mixture of superheated steam (10) and oxygen (11) raises the temperature of the biomass in the biomass gasification chamber (16) from approximately 430°C to approximately 730°C, making it possible to initiate a water-gas reaction in the biomass gasification chamber (16).

[0059] Although oxygen (11) directly contacts the biomass active surface in the biomass pyrolysis chamber (1) and biomass gasification chamber (16), the amount of oxygen (11) is controlled and the gas penetrates the fuel layer from bottom to top in a time of more than 4 seconds. Therefore, carbon will almost only generate CO instead of CO2: C + CO2 → 2CO + 172.43 kJ / mol

[0060] The biomass pyrolysis chamber (1) will produce a considerable amount of soot and tar, which are necessary for the present invention because the present invention requires unburned carbon to combine with the oxygen produced by hydrolysis.

[0061] Since the biomass pyrolysis chamber (1) and the biomass gasification chamber (16) only blow in oxygen (11) instead of air, the nitrogen content in the synthesis feed gas (14) is low and comes almost entirely from nitrogen-containing compounds in the biomass. The low nitrogen content of the synthesis feed gas (14) has high reactivity, which is an important prerequisite for the effective non-pressurized reforming of the synthesis feed gas (14).

[0062] Of the 4150 kg / h (3% moisture) of biomass entering the biomass pyrolysis chamber (1) and the biomass gasification chamber (16), about 2 / 3 is pyrolyzed and gasified, and the remaining about 1 / 3 of the gasification residue is transferred to the low-temperature moving grate combustion chamber (4) for combustion to produce 1550°C heated flue gas (22) for this example.

[0063] As soon as the touch sensor (5) in the biomass gasification chamber (16) sends a signal, the square bag of straw (2) will be pushed until the biomass gasification chamber (16) is filled again.

[0064] Synthetic feed gas (14) from the biomass pyrolysis chamber (1) and the biomass gasification chamber (16) is discharged through the synthetic feed gas release channel (6). The fuel gas used to produce heating gas leaves the low-temperature moving grate combustion chamber (4) through the flue gas mixing channel (7). The amount of added oxygen (11) can be finely adjusted according to the temperature in the biomass gasification chamber (16).

[0065] The inner sides of both the biomass pyrolysis chamber (1) and the biomass gasification chamber (16) are lined with ceramic insulation material to prevent low-speed heat loss and tar condensation. Between the biomass gasification chamber (16) and the low-temperature moving grate combustion chamber (4), there is a rotary-driven water-cooled conveying roller (17) that removes the gasification residue from the biomass gasification chamber (16) and evenly spreads it on the moving grate of the low-temperature moving grate combustion chamber (4).

[0066] At least one rotatable sealing plate (18) presses down on the biomass fuel layer by its own weight, thereby minimizing gas convection between the biomass pyrolysis chamber (1) and the biomass gasification chamber (16). In addition, the gas pressure in the low-temperature moving grate combustion chamber (4) and the biomass gasification chamber (16) can always be kept the same to prevent gas flow.

[0067] Figure 2 The displayed low-temperature moving grate combustion chamber (4) is equipped with a flue gas vortex burner (19) with a variable flue gas nozzle (20) and another flue gas vortex burner.

[0068] High-temperature combustion air (21) preheated to 600°C is added to the flue gas mixing channel (7), and this process generates approximately 12800 Nm³ of combustion air. 3 The heating gas is supplied at a temperature lower than the maximum withstand temperature of 1600°C for commercially available silicon carbide tubes; in this embodiment, the temperature is 1550°C. The superheated steam (10) and high-temperature combustion air (21) enable heat return to the process, ultimately achieving high efficiency.

[0069] Synthesis feed gas (14) and 1550°C heated flue gas (22) are drawn into a multi-stage high-temperature gas-to-gas silicon carbide tube heat exchanger from different directions. Synthesis feed gas (14) flows in silicon carbide heat exchange tube (23) and is heated by the 1550°C heated flue gas (22) flowing counter-currently outside the silicon carbide tube (23). Synthesis feed gas (14) is reformed during the heating process and releases heat again into superheated steam (10) and high-temperature combustion air (21).

[0070] The multi-stage high-temperature gas-to-gas silicon carbide tube heat exchanger in the device of the present invention is variable in terms of system length, counter-current or direct current direction selection, number of silicon carbide heat exchange tubes (23), and number of heating or cooling gases involved. It consists of four parts: initial heat exchange unit (30) for synthesis feed gas reforming, main heat exchange unit (31) for synthesis feed gas reforming, superheated steam heat exchange unit (32) and combustion air preheating unit (33).

[0071] Synthetic feed gas (14) flows into the initial heat exchange unit (30) of synthetic feed gas reforming at approximately 550°C. The heat exchange tube bundle of the initial heat exchange unit of synthetic feed gas reforming consists of 96 silicon carbide heat exchange tubes (23) that are 1 meter long, thus the tensile stress in the material is small and the risk of vibration is small.

[0072] The initial heat exchange unit (30) for the reforming of the synthesis feedstock gas is 9 meters long. The synthesis feedstock gas (14) is heated to about 1020°C and transferred to the main heat exchange unit (31) for the reforming of the synthesis feedstock gas through the heat-resistant ceramic transition channel (24). A vortex generator (25) is arranged in front of the silicon carbide heat exchange tube (23) to realize the high-speed vortex rotation flow of the synthesis feedstock gas in the silicon carbide heat exchange tube.

[0073] In the main heat exchange unit (31) of the synthesis feed gas reforming, the temperature of the synthesis feed gas (14) is further increased to 1150°C, preferably reaching 1300°C, and the flow velocity of the synthesis feed gas (14) in the silicon carbide heat exchange tube (23) is greater than 88 m / s. The steam flow that has been depressurized by the pressure reducer (27) is heated to 900°C in the hot steam heat exchange unit (32) and then blown into the biomass pyrolysis chamber (1) and the biomass gasification chamber (16) by the high temperature fan (28) through the superheated steam and oxygen supply chamber (3).

[0074] In the combustion air preheating unit (33), fresh air (29) is heated into high-temperature combustion air (21) and the high-temperature process heat in the reformed syngas is recovered. The reformed syngas is cooled to about 280-350°C. The reformed syngas (34) after dust removal can be used immediately for subsequent methanol synthesis.

[0075] The process requires a negative pressure of at least 7500 Pa from the high-pressure blower (35), therefore, in this example, a second induced draft fan (36) is configured for the reformed syngas (34) after dust removal by the dust collector (37). The second induced draft fan (36) contains a filter tube made of ceramic fiber, thus providing temperature resistance. The reformed syngas (34) after dust removal can now be pressurized and used directly for methanol synthesis without reheating.

[0076] The flue gas heated at 1550℃ (22) leaves the multi-stage high-temperature gas-to-gas silicon carbide tube heat exchanger and is sent to the steam generator (38) at a temperature of about 900℃ to produce 0.5MPa saturated steam at a rate of 3500kg / h.

[0077] The exhaust gas, which is about 500°C after saturated steam is produced in the steam generator (38), mixes with fresh air (29) to form dry gas (39) at about 90-100°C. The dry gas (39) is sent to the straw bale drying module (8) by the fan (40) to dry the square bale straw (2) to about 3% moisture and about 45-50°C.

[0078] The temperature of the straw bale drying module (8) is about 45°C. The humid exhaust gas is discharged through the chimney, resulting in an energy loss of about 5% of the primary energy supply, which is only equivalent to 5% of the feed of 5800 kg / hour (30% moisture), or about 290 kg / hour of straw.

[0079] Figure 3 A cross-sectional view of the multiple high-temperature gas-to-gas silicon carbide tube heat exchanger of the present invention is shown. Ninety-six silicon carbide heat exchange tubes (23) are arranged in the cross-section, all housed within a high-temperature resistant partition wall (26) constructed of refractory concrete, exhibiting high abrasion resistance and a maximum withstand temperature of 1650°C. Externally, a load-bearing wall (41) made of refractory bricks is arranged, behind which is a 12 cm thick ceramic fiber insulation layer (45) composed of ceramic fiberboard.

[0080] In this embodiment, the multiple high-temperature gas-to-gas silicon carbide tube heat exchanger is arranged on a two-part equipment foundation (43), thus enabling heat to expand towards the center. A load-bearing arch (44) made of refractory concrete is placed on top, and a ceramic fiber insulation layer (45) is placed below the load-bearing arch (44).

[0081] The ceiling of the multi-high temperature gas-to-gas silicon carbide tube heat exchanger in this embodiment consists of a curved composite cover containing a curved load-bearing steel plate (46) and a large number of supports (47) for fixing the dome. The composite cover is provided with a number of fixing hooks (48) made of stainless steel for suspending and fixing the insulation layer (49) and the refractory concrete (50).

[0082] Hot air (51) is extracted from the space between the ceramic structure and the outer casing of the multi-stage high-temperature gas-to-gas silicon carbide tube heat exchanger for cooling and to create a low vacuum, minimizing the entry of air into the multi-stage high-temperature gas-to-gas silicon carbide tube heat exchanger due to structural leaks (such as cracks).

[0083] Figure 4 A partial plan view of a multi-stage high-temperature gas-to-gas silicon carbide tube heat exchanger is shown, where the silicon carbide heat exchange tubes (23) are 1 meter long and fixed in a high-temperature resistant partition wall (26), and each silicon carbide heat exchange tube (23) can expand freely.

[0084] To enable the masonry sections to expand, the load-bearing walls (41) here contain expansion plates (52) made of ceramic fibers, as do the equipment foundations (43). The ceiling is constructed according to CN202210787852.4, so it can be expanded longitudinally without leakage.

[0085] Figure 5 The image shows the butt joint of the silicon carbide heat exchange tube (23) within the silicon carbide connecting sleeve (55) of the high-temperature resistant partition wall (26). The casting mold (53) will burn during commissioning after the refractory concrete ceramic partition wall (26) is completed. Since the high temperature difference means that slight thermal expansion cannot be completely avoided, the silicon carbide heat exchange tube (23) is installed in a splice (56) made of ceramic fibers soaked in graphite paste, where the graphite particles provide a sealing effect and facilitate sliding.

[0086] The silicon carbide heat exchange tube (23) is firmly bonded to the silicon carbide connecting sleeve (55) at the adhesive joint (56). The silicon carbide connecting sleeve (55) is fixed to the cast refractory concrete to prevent displacement. The silicon carbide heat exchange tube (23) can slide within the silicon carbide connecting sleeve (55). The thickness of the adhesive joint (56), made of ceramic fibers soaked in graphite paste, gradually decreases from the center outwards, so the winding will not slip out of the load-bearing wall (41) or the insulation layer (42).

[0087] The vacuum bonding (56) in the silicon carbide heat exchange tube (23) is held in place by negative pressure along the direction of the silicon carbide connecting sleeve (55), thereby sealing the gap between the silicon carbide connecting sleeve (55) and the silicon carbide heat exchange tube (23).

[0088] according to Figure 5 The arrangement shows the situation at a temperature of approximately 1050°C. There is a free space between the two silicon carbide heat exchange tubes (23), the length of which corresponds to the wall thickness of the silicon carbide heat exchange tube (23) (=6mm). If the distance is too large, it may increase the pressure loss.

[0089] When the synthesis feed gas (14) passes through the turbulence splitting edge (57) in the cross section of the main heat exchange unit (31) of the synthesis feed gas reforming at a speed of 85 m / s (=306 km / h), turbulence will occur and vacuum, pressure pulse and similar void jet effects will be generated in free space.

[0090] In a multi-stage high-temperature gas-to-gas silicon carbide tube heat exchanger, the temperature of the main heat exchange unit (31) for the synthesis feed gas reforming reaches at least 1150°C and can reach up to about 1300°C. Under these high temperatures and pressures below atmospheric pressure, the H0 bond force of water molecules decreases, causing water vapor to enter a transitional stage of plasma aggregation. At this time, the pressure pulse will trigger the decomposition of water molecules.

[0091] The pressure pulse effect here is generally strong only in the outer layer of the atmosphere, but the total length of the multiple high-temperature gas-gas silicon carbide tube heat exchanger in this embodiment is 31 meters. The synthesis feed gas passes through 31 turbulence split edges (57) in the silicon carbide heat exchange tube (23), of which at least about 20 turbulence split edges (57) have a temperature exceeding 1000°C. Therefore, these pressure pulse effects will superimpose and cover the entire flow rate and flow process of the synthesis feed gas (14).

[0092] If the inner diameter of the silicon carbide heat exchange tube (23) is reduced and the number of silicon carbide heat exchange tubes (23) is increased, the total length of the turbulence splitting edge (57) will also be extended. In this embodiment, the inner diameter of the silicon carbide heat exchange tube (23) is 45 mm.

[0093] During water splitting, oxygen ions released combine with free carbon atoms to form CO, and hydrogen ions combine with each other to form H2. Both of these reactions release more energy and further produce hydrogen: CO + H2O → CO2 + H2 (-41.13 kJ / mol)

[0094] Figure 6 A possible design for a vortex generator (25) made of silicon carbide is shown. Synthesis feed gas (14) can flow tangentially into the vortex generator (25) through a channel (58), and a cap (59) is glued and fixed to the open end of the vortex generator (25). The part on the right side of the figure can be directly connected to the silicon carbide heat exchange tube (23) in the high-temperature resistant partition wall (26).

[0095] In this embodiment, the inner diameter of the vortex generator (25) is the same as that of the silicon carbide heat exchange tube (23), which is 45 mm. The size of the slot corresponds to the internal cross-section of the silicon carbide heat exchange tube (23). Here, the slot (58) is 100 mm long and 16 mm wide. The vortex speed of the synthesis feed gas (14) with a flow velocity of about 77 m / s after entering the vortex generator (25) at 1020°C can reach about 45,000 rpm.

[0096] The centrifugal force acting on 1 gram of gas particles is approximately 350 N, which is about 35,000 times their own weight. At such high temperatures and with high kinetic energy, the synthesis feedstock gas (14), which contains almost no inert gases, rotates rapidly under the influence of the Earth's magnetic field. Combined with the pressure pulse effect from the vacuum cavity jet effect, this makes it possible for the synthesis feedstock gas (14) to undergo reforming without pressurization, thereby achieving a hydrogen content exceeding 55% in the synthesis feedstock gas (14).

[0097] This means that the device of the present invention can eliminate the need to add hydrogen to the synthetic feedstock gas (14) from other sources, and retain the value of straw ash as fertilizer in the field to the maximum extent.

[0098] The multi-stage high-temperature gas-to-gas silicon carbide tube heat exchanger of the present invention can provide higher reaction temperatures for chemical processes and enhance the physical effects of these chemical processes, and achieve high energy efficiency by recovering process heat at high temperature levels.

[0099] This multi-stage high-temperature gas-to-gas silicon carbide tube heat exchanger and its physical enhancement effect are also applicable to other chemical processes, such as industrial processes for producing hydrogen from natural gas.

[0100] Mathematically speaking, about 4% of the primary energy introduced by the device of this invention is lost with the wet waste gas generated during straw drying. Even if the system may have about 2% radiation loss, 94% of the primary energy is still retained in the syngas.

[0101] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An apparatus for producing syngas from non-pressurized reformed biomass pyrolysis gasification, comprising a straw bale drying module, a biomass pyrolysis chamber, a biomass gasification chamber, a low-temperature moving grate combustion chamber, a flue gas vortex burner, a multiple high-temperature gas-to-gas silicon carbide tube heat exchanger, and a steam generator; characterized in that... Synthetic feed gas (14) generated from the biomass pyrolysis chamber (1) and the biomass gasification chamber (16) enters a multi-stage high-temperature gas-to-gas silicon carbide tube heat exchanger for heating, conversion, and cooling. Part of the waste heat generated by this heat exchanger can be used in the straw bale drying module to dry the straw bales. The silicon carbide heat exchange tubes (23) are kept at a certain distance from each other, forming a free space. The synthetic feed gas (14) is convectively heated from the outside by the externally heated flue gas (22) to at least [temperature missing]. At 1150℃, the flow velocity of the synthesis gas in the silicon carbide heat exchange tube (23) reaches 85m / s. The synthesis feed gas (14) flows continuously through multiple silicon carbide heat exchange tubes (23). Each silicon carbide heat exchange tube (23) has a turbulent flow splitting edge (57) at its end. The synthesis feed gas (14) is introduced into the silicon carbide heat exchange tube (23) in a vortex rotation manner, generating a centrifugal force of 350N acting on the gas particles of the synthesis feed gas (14) with a mass of 1 gram.

2. The apparatus for producing syngas from unpressurized reformed biomass pyrolysis gasification according to claim 1, characterized in that, In the biomass pyrolysis chamber (1) at an upward angle, the biomass that falls under gravity is pushed from bottom to top and pyrolyzed. The pyrolyzed biomass enters the biomass gasification chamber (16) at a downward angle of 33 degrees for carbon gasification. The biomass in the biomass gasification chamber (16) slides downward only by gravity. At least 1 / 3 of the biomass fed into the biomass pyrolysis chamber (1) in the biomass gasification chamber (16) is transferred to the subsequent low-temperature moving grate combustion chamber (4).

3. The apparatus for producing syngas from unpressurized reformed biomass pyrolysis gasification according to claim 2, characterized in that, Biomass fuel is continuously fed into the biomass pyrolysis chamber (1) to form a closed fuel layer at least 1.2 meters high, while in the biomass gasification chamber (16) a fuel layer at least 0.9 meters high is maintained.

4. The apparatus for producing syngas from unpressurized reformed biomass pyrolysis gasification according to claim 2, characterized in that, After the biomass enters the biomass pyrolysis chamber (1), superheated steam (10) at a temperature of 850°C and a pressure of about 200-1000Pa is first blown in from the superheated steam introduction zone (13) at the bottom, according to the biomass mass entering the biomass pyrolysis chamber (1) being about 6-9%. Then, a mixture of superheated steam (10) at 850°C and oxygen (11) at a pressure of about 2-2.5:1 is blown in from the superheated steam and oxygen mixture introduction zone (15) at the bottom, according to the biomass mass entering the biomass pyrolysis chamber (1) being about 18-23% and the moisture content being 3%.

5. The apparatus for producing syngas from unpressurized reformed biomass pyrolysis gasification according to claim 2, characterized in that, According to the biomass gasification chamber (16), the biomass mass is 85-100%, the moisture content is 0%, and a mixture of superheated steam (10) and oxygen (11) at a temperature of 850°C is blown into the chamber. The weight ratio of oxygen in the mixture is about 1-4%, and the weight ratio of oxygen should be adjusted according to the temperature in the biomass gasification chamber (16).

6. The apparatus for producing syngas from unpressurized reformed biomass pyrolysis gasification according to claim 2, characterized in that, The amount of biomass gasification residue transferred from the biomass gasification chamber (16) can be adjusted by the water-cooled feed roller (17) and form a uniform fuel layer in the low-temperature moving grate combustion chamber (4), on which there is at least one rotatable sealing plate (18) pressed by its own weight on the biomass fuel layer.

7. The apparatus for producing syngas from unpressurized reformed biomass pyrolysis gasification according to claim 1, characterized in that, The silicon carbide heat exchange tubes (23) are connected to each other in the cast high-temperature resistant partition wall (26) by silicon carbide connecting sleeves (55). The silicon carbide connecting sleeves (55) are firmly connected to the tube end of the silicon carbide heat exchange tubes (23) and the adhesive (56) made of ceramic fibers soaked in graphite paste.

8. The apparatus for producing syngas from unpressurized reformed biomass pyrolysis gasification according to claim 1, characterized in that, There is a free space between the two silicon carbide heat exchange tubes (23) in the silicon carbide connecting sleeve (55) with a length of 1-3 times the wall thickness of the silicon carbide heat exchange tubes (23). When the synthesis raw material gas (14) passes through the turbulent diversion edge (57) at high speed, turbulence will occur and vacuum, pressure pulse and similar void jet effects will be generated in the free space.

9. The apparatus for producing syngas from unpressurized reformed biomass pyrolysis gasification according to claim 1, characterized in that, The multi-stage high-temperature gas-gas silicon carbide tube heat exchanger for reforming the synthesis feed gas (14) comprises two parts: an initial heat exchange unit (30) for reforming the synthesis feed gas and a main heat exchange unit (31) for reforming the synthesis feed gas. The initial heat exchange unit (30) and the main heat exchange unit (31) for reforming the synthesis feed gas are connected to each other through a heat-resistant ceramic transition channel (24). The synthesis feed gas (14) reaches a temperature of 1000°C in the initial heat exchange unit (30) for reforming the synthesis feed gas, and then flows through a vortex generator (25) made of silicon carbide located at the front end of the silicon carbide heat exchange tube (23) in the main heat exchange unit (31) for reforming the synthesis feed gas. The high-speed vortex rotation enters the main heat exchange unit (31) for reforming the synthesis feed gas.

10. The apparatus for producing syngas from unpressurized reformed biomass pyrolysis gasification according to claim 1, characterized in that, The pressure in the biomass pyrolysis chamber (1), the biomass gasification chamber (16), and the low-temperature moving grate combustion chamber (4) is always adjusted to the same set value.

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