Process for reforming synthesis gas from biomass pyrolysis gasification without pressurization

Abstract

The invention relates to a process for reforming synthesis gas from biomass pyrolysis gasification without pressurization, which is suitable for methanol production by generating hydrogen-rich gas from cellulose-rich biomass through non-pressure conversion. 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] The process of the present invention belongs to the field of biomass energy conversion technology, and its purpose is to produce hydrogen-rich gas from cellulose-rich biomass fuel, especially from whole bales of straw, and the produced gas is suitable for synthesizing methanol or extracting hydrogen. After the gasified synthesis gas is convectively heated to above 1000°C, it is reformed without pressure under the action of strong airflow, and the heat in the entire process is returned to the process through multiple high-temperature heat exchanges. The ash produced by the process will be returned to the field as fertilizer. Background Art

[0002] So far, the production of hydrogen-rich gas using biomass requires a temperature of at least 1150°C 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 taken out of the pressure reactor will be severely depreciated whether used as fertilizer or building material.

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

[0004] For example, the straw-based hydrogen-rich gas according to DE102005006305A1 is firstly pyrolyzed to obtain coke, then ground to form a pumpable slurry and press it into a high-pressure, high-temperature gasification reactor, and this process places very high demands on the pump. In the reactor, the gas temperature in the reactor must be raised to above 1150°C by internal combustion for high-temperature rapid gasification and conversion, resulting in a rise in the CO2 content to about 30%, making the conversion reaction very slow. Since there is no way to enhance the above reaction process by airflow or other technical routes, the only option at present is to apply high pressure, but since the generation of hydrogen is a process of cracking hydrocarbons and water, high pressure itself will be counterproductive. Removing CO2 before methanol synthesis will also cause wastewater pollution and energy loss, because the synthesis gas will have to be heated again afterwards.

[0005] At present, there is no process flow that can completely return 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 the biomass synthesis gas production project will be affected, and the transportation of straw used for synthesis gas may be longer, which contradicts the principle of distributed utilization of straw.

[0006] If the ash cannot be effectively separated from the biomass coke, many low-melting-point minerals in the ash will melt and be included in the synthesis gas when the slurry is gasified at 1150°C. This will not only cause the fertilizer value of these minerals to be lost, but also cause coking, heat exchange surface corrosion, or synthesis gas purification due to changes in flue gas temperature, which will bring additional burdens.

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

[0008] The unpressurized gas reforming process of the present invention requires a higher quality synthesis gas with low content of tar, acid vapor, smoke and dust, and this unpressurized 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 high temperature of 930℃ that the industrial thermal hydrogen tubular reformer can withstand cannot effectively meet the temperature requirements of biomass reforming syngas. Therefore, when the industrial thermal hydrogen tubular reformer is used for biomass syngas reforming, the pressure needs to be increased to above 11MPa, but the heat exchanger made of ceramic high-temperature resistant materials cannot be used for such pressure.

[0010] Although the discontinuous heat exchange process may meet the high temperature requirements of syngas reforming, it cannot ensure the stability of the reforming process temperature and cannot achieve sufficient separation of the gas. The cavitation jet effect similar to that of wind turbines can accelerate the cracking of fluids, especially liquids, but the cavitation jet effect has not yet been used for gas conversion at extremely high temperatures.

[0011] At present, there is no case of continuous operation of a high-temperature gas-to-gas heat exchanger at 1600°C and simultaneous heat exchange between one gas and several other gases. When biomass pyrolysis coke is used to produce synthesis gas, the combustion of hydrogen-rich pyrolysis gas can meet the heating needs, but it is impossible to achieve a high hydrogen content in the synthesis gas.

[0012] Known process currently cannot achieve CO:H2=1:2 or higher ratio in biomass syngas or synregas. To achieve the above ratio, either the CO content in the syngas or synregas must be reduced, or hydrogen from other sources must be added to the syngas or synregas. Summary of the invention

[0013] The task of the present invention is to produce a gas suitable for methanol synthesis or hydrogen purification with a hydrogen content of more than 55% from biomass, especially from a whole bag of straw, through unpressurized gas reforming. The high pressure of other processes will be replaced by other processes of the present invention in the process of the present invention. The low temperature and long-term gasification in the process of the present invention are intended to maintain the value of straw ash as fertilizer. The dust content and inert gas content of the process output gas of the present invention do not require gas cleaning, and the hydrogen in the biomass enters the synthesis gas in the form of hydrogen. By recycling heat at high temperature, the primary energy utilization rate of the process of the present invention is above 94%.

[0014] The unpressurized gas reforming process should also be applicable to other similar chemical processes.

[0015] The biomass in the process of the present invention includes whole packages of crop stalks, cotton stalks, chopped grass, mushroom culture bags and chopped energy crops.

[0016] The process of the present invention first dries the biomass to a moisture content of about 5% and a temperature of about 50°C, which makes it possible to introduce high-temperature superheated steam into the biomass in the subsequent biomass gasification. The process heat returned under high temperature conditions can save fuel, reduce the combustion process and activate the surface reaction activity of the biomass particles.

[0017] The heating, conversion and cooling of the synthesis gas of the present invention are all carried out in a multiple high-temperature heat exchanger composed of silicon carbide heat exchange tubes, which are connected to each other through a connecting sleeve, and the heat exchange tubes in the connecting sleeve are at a certain distance from each other to form a free space. A turbulent flow splitting edge is formed at the end of each silicon carbide heat exchange tube, and the flue gas is turbulent at the turbulent flow splitting edge and generates a pressure pulse that can improve the gas conversion rate.

[0018] The raw syngas enters the silicon carbide heat exchange tube in a vortex rotation mode. The inner diameter size design of the silicon carbide heat exchange tube and the gas vortex speed should make the centrifugal force acting on 1 gram of gas particles reach 350N. The raw syngas in the silicon carbide heat exchange tube is heated by the heating gas outside the silicon carbide heat exchange tube to at least 1150℃ and the flow rate reaches more than 85m / s.

[0019] The number of ions in the raw synthesis gas containing water vapor will increase with the increase of temperature and begin to ionize at 1000°C. The water vapor in the synthesis raw gas enters the plasma state at 1050°C. At this time, the bonding force of water molecules becomes weaker. The current and charge generated in the vortex rotating airflow in the earth's magnetic field will interact with the water molecules with a dipole structure and generate energy that can offset the bonding force of water molecules and induce extensive dissociation of water molecules. The hydrogen ions and oxygen ions released by dissociation in this way are highly reactive and can be intensively converted without pressure.

[0020] The process of the present invention includes a front biomass pyrolysis chamber and a rear biomass gasification chamber, wherein the biomass gasification chamber can send a material level signal at any time to adjust the fuel feed amount of the process of the present invention. According to the process of the present invention, the gasification process will produce gasified gas with low CO2 content, nitrogen content below 3%, and high smoke 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, and a fuel layer at least 0.9 meters high is maintained in the biomass gasification chamber. Water vapor and oxygen are blown into the fuel layer from the bottom of the biomass pyrolysis chamber and the biomass gasification chamber and remain in close contact with carbon or unburned biomass for more than 3 seconds.

[0021] Steam at least 850°C is first blown into the steam inlet area of ​​the biomass pyrolysis chamber, 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 into the superheated steam and oxygen mixture inlet area. Since the superheated steam or superheated steam and oxygen mixture blown in stays in the fuel layer for a long time, the surface of the large biomass particles can only react with a small amount of oxygen and almost only produce CO without producing CO2.

[0022] In this process, carbon from soot and tar vapors combines with oxygen molecules, especially from water splitting, which makes hydrogen ions free to combine with each other to produce more hydrogen (H2).

[0023] In order to obtain higher quality synthetic raw gas, biomass pyrolysis and biomass gasification are carried out successively in two spaces. In order to prevent the formation of free space in the fuel layer when the fuel is gasified and the invasion of high-oxygen gas, the straw in the biomass pyrolysis chamber is pyrolyzed in the process of being pushed upward. Under the action of gravity, the biomass is always in a compacted state in the upward direction, so the gas always maintains close contact with the solid biomass.

[0024] In order to achieve a stable compacted state of biomass in the biomass gasification chamber, the bottom plate of the biomass gasification chamber can be designed to be at an angle of 33 degrees to the horizontal direction, where the biomass slides down by its own weight to prevent the generation of free space. For this reason, the fuel layer in the biomass gasification chamber is kept more than 0.9 meters thick, and the gas constantly changes its flow direction between the biomass particles in the fuel layer and repeatedly contacts the biomass surface.

[0025] In the general conventional biomass pyrolysis and gasification process, as the biomass mass decreases, the contact between gas and fuel will also decrease, the gasification temperature will increase and more CO2 will be produced. According to the process of the present invention, the volatile matter of the biomass entering the biomass pyrolysis chamber and the biomass gasification chamber is released in the form of synthetic raw gas through pyrolysis and gasification, and the volatile matter released by pyrolysis and gasification accounts for about 2 / 3 of the total weight of the biomass. After the volatile matter is released by gasification, the biomass residue, which accounts for about 1 / 3 of the total weight of the fed biomass, will be transferred from the biomass gasification chamber to the low-temperature moving grate combustion chamber to avoid producing more CO2 in the biomass gasification chamber. The synthetic raw gas released by pyrolysis and gasification of the biomass pyrolysis chamber and the biomass gasification chamber contains almost all the hydrogen in the biomass raw material. After calculation, the hydrogen content of the synthetic raw gas released at this time can exceed 21%.

[0026] The biomass gasification residue transferred to the low-temperature moving grate combustion chamber is mainly composed of ungasified carbon fiber, biochar, ash and soil, etc. The structural design of the low-temperature moving grate combustion chamber can realize long-term and sufficient low-temperature combustion of these biomass residues. According to the process of the present invention, the biomass is pyrolyzed, gasified and burned in three continuous spaces, which makes it possible to optimize the three process processes and parameters of pyrolysis, gasification and combustion respectively.

[0027] The speed at which the ungasified biomass residues are removed from the biomass gasification chamber is regulated by a water-cooled feed roller, in this way creating an almost uniform residue layer in the low-temperature moving grate combustion chamber, which is sealed at its top by a refractory ceramic rotatable sealing plate at the top.

[0028] To prevent gas convection between the low-temperature moving grate combustion chamber and the biomass gasification chamber, the pressures in the low-temperature moving grate combustion chamber and the biomass gasification chamber are automatically adjusted to the same set value.

[0029] To prevent air from entering the biomass pyrolysis chamber, the biomass needs to enter the biomass pyrolysis chamber through the fuel gate and the sealed channel between the fuel drying module and the biomass pyrolysis chamber. Superheated steam with a temperature of not less than 850°C, preferably 900°C, is first blown into the lower part of the superheated steam introduction area of ​​the biomass pyrolysis chamber, and the blowing amount is about 6-9% (3% moisture) of the feed biomass mass.

[0030] Then, a mixture of 900°C superheated steam and oxygen in a ratio of 2-2.5:1 is blown into the superheated steam and oxygen mixture introduction zone, and the blowing amount is approximately 18-23% (3% moisture) of the biomass equivalent to the feed biomass.

[0031] The biomass in the biomass pyrolysis chamber is heated to about 380-430°C, and about 1 / 3 of the biomass fed into the biomass pyrolysis chamber is pyrolyzed.

[0032] The biomass then enters the biomass gasification chamber for carbon gasification. To achieve the temperature required for carbon gasification, a mixed gas of superheated steam and oxygen at at least 850°C (preferably 900°C) with an oxygen content of 1-4% is input. The input amount of the superheated steam and oxygen mixed gas is 85-100% of the biomass entering the biomass gasification chamber, and the input amount can be adjusted according to the temperature of the biomass gasification chamber.

[0033] During the carbon gasification process, a mixture of superheated steam and oxygen at a temperature of at least 850°C, preferably 900°C, heats the biomass from 420-450°C to 700-740°C and produces CO and H2.

[0034] C+H2O→CO+H2(-151,5kJ / mol)

[0035] All gases flow upward at a low speed in the biomass fuel layer. During the gas flow, small smoke particles can be moved but dust is hardly brought along, so that there is almost no sediment in the downstream channels and heat exchange surfaces.

[0036] The synthetic raw gas from the biomass pyrolysis chamber and the biomass gasification chamber is released at about 500-560°C into a multiple high-temperature gas-gas silicon carbide tube heat exchanger composed of silicon carbide tube bundles for reforming.

[0037] High temperature heat exchange occurs in short, connected, continuous silicon carbide heat exchange tubes, which form a continuous tube bundle. Synthetic raw gas flows in the silicon carbide heat exchange tubes, and the heating gas with an initial temperature of 1550°C flows through the outside of the silicon carbide heat exchange tubes to heat the synthesis gas in the silicon carbide heat exchange tubes to at least 1150°C, preferably to 1300°C, to reform the pyrolyzed and gasified synthetic raw gas.

[0038] To overcome thermal expansion, the silicon carbide tube bundle is composed of many tube sections made of silicon carbide. These silicon carbide tube sections are connected to each other through silicon carbide coupling sleeves inserted into the high-temperature concrete partition wall. The silicon carbide coupling sleeve is firmly connected to the silicon carbide tube end. The end of the silicon carbide tube section can be sealed by winding ceramic fibers impregnated with graphite paste. In this way, each silicon carbide heat exchange tube is locked on one side of the high-temperature concrete partition wall, and the other end can slide in the wound ceramic fibers to overcome thermal expansion displacement.

[0039] A free space about 1-3 times the wall thickness of the SiC heat exchange tube will be formed between the two SiC heat exchange tube ends in the SiC coupling sleeve. The airflow flowing through this free space and the turbulent flow diversion edges of the SiC heat exchange tube will be disturbed and produce a vacuum similar to the cavity jet effect and form extreme turbulence with pressure pulses. Water molecules in a high temperature state and with weakened HO bonding force will be cracked.

[0040] Although such water molecule splitting is limited to the vicinity of the turbulent flow diversion edge, the synthetic raw gas will undergo many water molecule splittings when it flows through a long multiple high-temperature gas-gas silicon carbide tube heat exchanger for reforming.

[0041] The high temperature resistant partition wall of the multiple high temperature gas-gas silicon carbide tube heat exchanger in the process of the present invention is a flexible expansion plate made of ceramic fiber. On the premise of overcoming the expansion force in the horizontal and vertical directions, the silicon carbide tube heat exchanger in the process of the present invention can be designed to any length.

[0042] The heat in the reformed synthesis feed gas acts on the unpressurized steam at a temperature of up to 1300°C and heats the unpressurized steam to a maximum temperature of 900°C and heats the combustion air together with the synthesis feed gas to 600°C.

[0043] Almost all the process heat is recycled and applied to the process of the present invention through the multiple high-temperature gas-gas silicon carbide tube heat exchangers of the present invention, which is why the process of the present invention has high energy efficiency.

[0044] Except for the exhaust gas of about 50°C discharged at the tail of the system, almost all the heat energy in the heating gas after the reforming of the synthetic raw gas is recycled in the process of the present invention for air preheating, water heating, steam heating or biomass drying, and the thermal efficiency of the primary energy of the system is above 94%.

[0045] The corrosion-resistant silicon carbide tube can withstand a high temperature of 1600°C, so the input and output quantities of the synthetic raw gas can be freely set, and direct current or countercurrent heat exchange can be freely selected. The process of the present invention enables chemical process technology to be implemented at a higher temperature level in an innovative form. Based on this, the process of the present invention has chosen the name of a multiple high-temperature gas-to-gas silicon carbide tube heat exchanger.

[0046] The synthetic raw gas is sucked in under negative pressure through the blower. The heat exchange for reforming the synthetic raw gas consists of two parts: an initial heat exchange unit for reforming the synthetic raw gas and a main heat exchange unit for reforming the synthetic raw gas. In the initial heat exchange unit for reforming the synthetic raw gas, the synthetic raw gas is heated from 550°C to about 1000°C. In the main heat exchange unit for reforming the synthetic raw gas, the temperature of the synthetic raw gas is further increased to above 1150°C, preferably reaching 1300°C.

[0047] The initial heat exchange unit for synthetic raw gas reforming and the main heat exchange unit for synthetic raw gas reforming are connected to each other through a heat-resistant ceramic transition channel. The synthetic raw gas heated to 1000°C is accelerated by the vortex generator and rotates before entering the main heat exchange unit for synthetic raw gas reforming, thus inducing the so-called physical effect. The dynamic pressure generated in this way compensates for the lack of static pressure and improves the heat transfer capacity of the inner wall of the silicon carbide heat exchange tube.

[0048] Since the multiple high-temperature gas-gas silicon carbide tube heat exchangers in the process of the present invention are operated only under negative pressure, high-temperature resistant ceramic materials can be used in 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 material's compressive resistance and tolerance to leakage within the allowable range. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 A simplified side view of a system utilizing the process of the present invention is shown.

[0050] Figure 2 A schematic diagram of the system for reforming biomass synthesis feed gas is shown.

[0051] Figure 3 A cross-sectional view of a multiple high temperature gas-gas silicon carbide tube heat exchanger is shown.

[0052] Figure 4 A partial plan view of a multiple high temperature gas-gas silicon carbide tube heat exchanger is shown.

[0053] Figure 5 Shows the connection of silicon carbide heat exchange tubes in a coupling sleeve in a high temperature resistant partition wall.

[0054] Figure 6 A vortex generator made of silicon carbide tube is shown.

[0055] In the figure: 1-biomass pyrolysis chamber, 2-square straw bale, 3-superheated steam and oxygen supply chamber, 4-low temperature moving grate combustion chamber, 5-touch sensor, 6-synthetic raw gas release channel, 7-smoke mixing channel, 8-straw bag drying module, 9-pushing device, 10-superheated steam, 11-oxygen, 12-sealed channel, 13-superheated steam introduction area, 14-synthetic raw gas, 15-superheated steam and oxygen mixed gas introduction area, 16-biomass gasification chamber, 17-water-cooled feed roller, 18-rotatable sealing plate, 19-smoke vortex burner, 20-variable smoke nozzle, 21-high temperature combustion-supporting wind, 22-1550℃ heated smoke, 23-silicon carbide heat exchange 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-synthetic raw gas reforming initial heat exchange unit, 31-synthetic raw gas reforming main heat exchange unit, 32-superheated steam heat exchange unit, 33-combustion air preheating unit, 34-reformed synthetic gas after dust removal, 35-high pressure fan, 36-second induced draft fan, 37-dust collector, 38-steam generator, 39-drying gas, 40-fan, 41-load-bearing wall, 42-insulation layer, 43-equipment foundation, 44-bearing Heavy arch, 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 plate, 53-casting formwork, 54-ceramic fiber, 55-silicon carbide connecting sleeve, 56-bonding, 57-spoiler and diverter edge, 58-groove, 59-cap, 60-bag gate, 61-casting sealing plate, 62-unpressurized steam. DETAILED DESCRIPTION

[0056] This example is designed for producing synthetic raw gas and reforming with square bales of straw (2) with a size of 1.2x1.3x2.4 meters. The example system inputs 7 square bales of straw with a moisture content of about 30% and a weight of about 820 kilograms per hour. The biomass pyrolysis chamber (1) and the biomass gasification chamber (16) can accommodate about 8.5 square bales of straw for pyrolysis and gasification for a total of about 73 minutes, and output about 9000Nm 3 / h synthesis gas.

[0057] Figure 1 The system is shown to have a biomass pyrolysis chamber (1) at an elevation angle and a biomass gasification chamber (16) at an inclination angle. The square bale of straw (2) is pushed by a pushing device (9) to run on a conveyor belt perpendicular to the direction of travel and enter the biomass pyrolysis chamber (1) through a sealed passage (12) of a material bag gate (60). The square bale of straw (2) is always kept compacted during the pyrolysis process, and the gas and the straw are always kept in close contact.

[0058] After the square bale of straw (2) with a moisture content of less than 3% and a temperature of about 50°C leaving the straw bale drying module (8) enters the biomass pyrolysis chamber (1), superheated steam (10) of about 900°C is first blown into the biomass pyrolysis chamber (1) at a rate of about 320kg / h through the superheated steam introduction zone (13) located at the bottom to heat the bottom layer of the square bale of straw (2) to a reaction temperature of 600°C. Subsequently, a mixed gas with a pressure of 200-800Pa and composed of 900°C superheated steam (10) and oxygen (11) (0-20°C) in a ratio of 2.1:1 is blown into the biomass pyrolysis chamber (1) at a rate of 810kg / h through the superheated steam and oxygen mixed gas introduction zone (15) located at the bottom.

[0059] When the square bale of straw (2) leaving the biomass pyrolysis chamber (1) subsequently falls into the biomass gasification chamber (16) at an inclination angle of about 35 degrees, although the bale shape of the square bale of straw (2) and the straw gradually lose their mechanical strength as they are gasified, there is always a 90 cm thick fuel layer in the biomass gasification chamber (16), and the cavity of the biomass can still be sealed or compacted by its own weight when the biomass slides downward, and the time for the mixed gas of superheated steam (10) and oxygen (11) to pass through the biomass fuel layer may be as long as 3-4 seconds.

[0060] A mixed gas consisting of about 2750 kg / h of 900°C superheated steam (10) and about 60 kg / h of oxygen (11) blown into the biomass gasification chamber (16) participates in the gasification of the biomass gasification chamber (16). The heat of the mixed gas of superheated steam (10) and oxygen (11) increases the temperature of the biomass in the biomass gasification chamber (16) from about 430°C to about 730°C and makes it possible to initiate a water gas reaction in the biomass gasification chamber (16).

[0061] Although oxygen (11) directly contacts the active surface of biomass in the biomass pyrolysis chamber (1) and the biomass gasification chamber (16), the amount of oxygen (11) is controlled and the gas penetrates the fuel layer from bottom to top in more than 4 seconds, so carbon almost only generates CO instead of CO2: C+CO2→2CO+172,43kJ / mol

[0062] The biomass pyrolysis chamber (1) produces a considerable amount of smoke and tar, which are necessary for the process of the present invention because the process of the present invention requires unburned carbon to combine with the oxygen produced by hydrolysis.

[0063] Since only oxygen (11) but not air is blown into the biomass pyrolysis chamber (1) and the biomass gasification chamber (16), the nitrogen content in the synthetic raw gas (14) is low and comes almost exclusively from nitrogen-containing compounds in the biomass. The synthetic raw gas (14) with a low nitrogen content has a high reactivity, which is an important prerequisite for the effective non-pressurized reforming of the synthetic raw gas (14).

[0064] About 2 / 3 of the 4150 kg / h (3% moisture) biomass entering the biomass pyrolysis chamber (1) and the biomass gasification chamber (16) 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 heating flue gas (22) used in this example.

[0065] As long as the touch sensor (5) in the biomass gasification chamber (16) sends a signal, the bale of straw (2) will be pushed until the biomass gasification chamber (16) is filled again.

[0066] The synthetic raw gas (14) from the biomass pyrolysis chamber (1) and the biomass gasification chamber (16) is discharged from the synthetic raw gas release channel (6). The fuel gas used to produce the 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).

[0067] The inner sides of the biomass pyrolysis chamber (1) and the biomass gasification chamber (16) are lined with ceramic insulation materials to prevent low-speed temperature loss and tar condensation. A rotating water-cooled feed roller (17) is provided between the biomass gasification chamber (16) and the low-temperature moving grate combustion chamber (4) to remove the gasification residue in the biomass gasification chamber (16) and evenly spread it on the moving grate of the low-temperature moving grate combustion chamber (4).

[0068] At least one rotatable sealing plate (18) is pressed by its own weight above the biomass fuel layer, thereby minimizing the 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.

[0069] Figure 2 The low-temperature moving grate combustion chamber (4) shown is equipped with a flue gas vortex burner (19) with a variable flue gas nozzle (20) and a further flue gas vortex burner.

[0070] A high temperature combustion air (21) preheated to 600°C is added to the flue gas mixing channel (7). This process generates about 12800Nm 3 / h of heating gas, the temperature of which is lower than the highest tolerable temperature of commercially available silicon carbide tubes, 1600°C, and in this embodiment the temperature is 1550°C.

[0071] The superheated steam (10) and the high-temperature combustion-supporting air (21) make it possible to return the heat in the process of the present invention to the process and ultimately achieve high efficiency.

[0072] The synthesis raw gas (14) and the 1550°C heated flue gas (22) are sucked into multiple high-temperature gas-to-gas silicon carbide tube heat exchangers from different directions. The synthesis raw gas (14) flows in the silicon carbide heat exchange tube (23) and is heated by the 1550°C heated flue gas (22) counter-flowing outside the silicon carbide tube (23). The synthesis raw gas (14) completes reforming during the heating process and releases heat again into the superheated steam (10) and the high-temperature combustion-supporting air (21).

[0073] The multiple high-temperature gas-gas silicon carbide tube heat exchangers in the process of the present invention are variable in terms of system length, countercurrent or direct flow direction selection, number of silicon carbide heat exchange tubes (23), number of heating or cooling gases involved, etc. It consists of four parts: a synthetic raw gas reforming initial heat exchange unit (30), a synthetic raw gas reforming main heat exchange unit (31), a superheated steam heat exchange unit (32) and a combustion air preheating unit (33).

[0074] The synthesis raw gas (14) flows into the synthesis raw gas reforming initial heat exchange unit (30) at about 550° C. The heat exchange tube bundle of the synthesis raw gas reforming initial heat exchange unit includes 96 silicon carbide heat exchange tubes (23) with a length of 1 meter, so the tensile stress in the material is small and the vibration risk is small.

[0075] The length of the initial heat exchange unit (30) for the synthesis raw gas reforming is 9 meters. The synthesis raw gas (14) is heated to about 1020°C and transferred to the synthesis raw gas reforming main heat exchange unit (31) 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 raw gas in the silicon carbide heat exchange tube.

[0076] In the main heat exchange unit (31) for reforming the synthetic raw gas, the temperature of the synthetic raw gas (14) is further increased to 1150°C, preferably to 1300°C, and the flow rate of the synthetic raw gas (14) in the silicon carbide heat exchange tube (23) is greater than 88 m / s. The steam flow reduced in pressure by the reducer (27) is heated to 900°C by the hot steam heat exchange unit (32) and then blown into the biomass pyrolysis chamber (1) and the biomass gasification chamber (16) through the high-temperature blower (28) and the superheated steam and oxygen supply chamber (3).

[0077] In the combustion air preheating unit (33), fresh air (29) is heated to high-temperature combustion air (21) and high-temperature process heat in the reformed synthesis gas is recovered. The reformed synthesis gas is cooled to about 280-350°C. The reformed synthesis gas (34) after dust removal can be immediately used for subsequent methanol synthesis.

[0078] This process requires a negative pressure of at least 7500Pa for the high pressure blower (35), so in this example, a second induced draft fan (36) is configured for the reformed synthesis gas (34) after dust removal by the dust collector (37), and the second induced draft fan (36) contains a filter tube made of ceramic fiber and is therefore temperature resistant. The reformed synthesis gas (34) after dust removal can now be pressurized and directly used for methanol synthesis without further heating.

[0079] The 1550°C heated flue gas (22) leaves the multiple high-temperature gas-gas silicon carbide tube heat exchanger and is sent to the steam generator (38) at a temperature of about 900°C to produce 0.5MPa saturated steam at 3500kg / h.

[0080] After saturated steam is produced in the steam generator (38), the waste gas with a temperature of about 500° C. is mixed 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) through a fan (40) to dry the square straw bale (2) to a moisture content of about 3% and a temperature of about 45-50° C.

[0081] The temperature of the straw bale drying module (8) is about 45°C. The emission of moist exhaust gas through the chimney results in energy loss within the range of about 5% of the primary energy supply, which is only equivalent to 5% of the feed rate of 5,800 kg / h (30% moisture), i.e. about 290 kg / h of straw.

[0082] Figure 3 The cross-sectional view of the multiple high-temperature gas-gas silicon carbide tube heat exchanger in the process of the present invention is shown. 96 silicon carbide heat exchange tubes (23) are arranged in the cross section, and these silicon carbide heat exchange tubes (23) are arranged in a high-temperature partition wall (26) cast with refractory concrete, which has high wear resistance and can withstand a maximum of 1650°C. A load-bearing wall (41) composed of refractory bricks is arranged outside, and behind the load-bearing wall (41) is a 12 cm thick ceramic fiber insulation layer (45) composed of ceramic fiber board.

[0083] The multiple high temperature gas-gas silicon carbide tube heat exchangers of this embodiment are arranged on a two-part equipment foundation (43), so that heat can expand toward the center. A load-bearing arch (44) made of refractory concrete is placed on the top, and below the load-bearing arch (44) is a ceramic fiber insulation layer (45).

[0084] The ceiling of the multiple high-temperature gas-gas silicon carbide tube heat exchanger of this embodiment is composed of a curved composite cover including a curved load-bearing steel plate (46) and a large number of brackets (47) for fixing the vault, and a number of fixing hooks (48) made of stainless steel are arranged in the composite cover for hanging and fixing the insulation layer (49) and refractory concrete (50).

[0085] Hot air (51) is extracted from the space between the ceramic structure and the outer package of the multiple high-temperature gas-gas silicon carbide tube heat exchanger to cool it and generate a low vacuum, thereby minimizing the entry of air into the multiple high-temperature gas-gas silicon carbide tube heat exchanger due to structural leakage (such as cracks).

[0086] Figure 4 A partial plan view of a multiple high-temperature gas-gas silicon carbide tube heat exchanger is shown, where the silicon carbide heat exchange tube (23) is 1 meter long and is fixed in a high-temperature resistant partition wall (26), and each silicon carbide heat exchange tube (23) can expand freely.

[0087] In order to expand the masonry in sections, the load-bearing walls (41) here contain expansion panels (52) made of ceramic fibers, as is the construction of the equipment foundation (43). The ceiling is made according to CN202210787852.4, so it can be expanded in the longitudinal direction without leakage.

[0088] Figure 5 The silicon carbide heat exchange tube (23) is shown butted against the silicon carbide coupling sleeve (55) in the high temperature resistant partition wall (26). The casting template (53) will burn out during the commissioning process after the refractory concrete ceramic partition wall (26) is cast. Since the high temperature difference means that small thermal expansion cannot be completely avoided, the silicon carbide heat exchange tube (23) is installed in a glue joint (56) made of ceramic fibers soaked in graphite paste. The graphite particles have a sealing effect and are easy to slide.

[0089] The silicon carbide heat exchange tube (23) is firmly connected to the silicon carbide coupling sleeve (55) at the adhesive joint (56), and the silicon carbide coupling sleeve (55) is fixed to the cast refractory concrete to prevent displacement. The silicon carbide heat exchange tube (23) can slide in the silicon carbide coupling sleeve (55). The thickness of the adhesive joint (56) made of ceramic fiber soaked in graphite paste gradually decreases from the center to the outside, so that the winding will not slide out of the load-bearing wall (41) or the insulation layer (42).

[0090] Since the vacuum adhesive (56) in the silicon carbide heat exchange tube (23) is sucked by negative pressure in the direction of the silicon carbide connecting sleeve (55), the gap between the silicon carbide connecting sleeve (55) and the silicon carbide heat exchange tube (23) is sealed.

[0091] according to Figure 5 The arrangement shows the situation at a temperature of about 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 (=6 mm) of the silicon carbide heat exchange tube (23). If the distance is too large, the pressure loss may increase.

[0092] When the synthetic raw gas (14) passes through the turbulent flow diversion edge (57) in the cross section of the synthetic raw gas reforming main heat exchange unit (31) at a speed of 85m / s (=306km / h), turbulence will occur and vacuum, pressure pulses and similar cavitation jet effects will be generated in the free space.

[0093] In the multiple high-temperature gas-gas silicon carbide tube heat exchangers, the temperature of the synthetic raw gas reforming main heat exchange unit (31) reaches at least 1150° C. and can reach up to about 1300° C. Under this high temperature and sub-atmospheric pressure, the HO bonding force of water molecules is reduced, so that the water vapor is in a transition stage of aggregation to a plasma state, and the pressure pulse at this time will cause the water molecules to crack.

[0094] The pressure pulse effect here is generally only strong 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 synthetic raw gas passes through 31 turbulent flow diversion edges (57) in the silicon carbide heat exchange tube (23), of which the temperature at at least about 20 turbulent flow diversion edges (57) exceeds 1000°C. Therefore, these pressure pulse effects will overlap (58) and flow tangentially into the vortex generator (25). The cap (59) is bonded and fixed to the open end of the vortex generator (25), and 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] The inner diameter of the vortex generator (25) in this embodiment is the same as the inner diameter 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). The slot (58) here is 100 mm long and 16 mm wide. The vortex speed of the synthetic raw gas (14) with a flow rate 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 about 350N, which is about 35,000 times its own weight. The synthetic raw gas (14) with such high temperature, high kinetic energy and almost no inert gas rotates at a high speed under the action of the earth's magnetic field. In addition, the pressure pulse effect from the vacuum cavity jet effect makes it possible to reform the synthetic raw gas (14) without pressurization, thereby achieving a hydrogen content of more than 55% in the synthetic raw gas (14).

[0097] This means that the device of the present invention can save the need to add hydrogen from other sources to the synthetic raw gas (14), and maximize the value of returning the straw ash as fertilizer to the field.

[0098] The multiple high-temperature gas-gas silicon carbide tube heat exchangers of the device 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 a high temperature level.

[0099] This multiple high-temperature gas-gas SiC tube heat exchanger and physical strengthening effect are also applicable to other chemical processes, such as the industrial process for producing hydrogen from natural gas.

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

[0101] Obviously, the above embodiments are only examples for clear explanation, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the protection scope of the present invention.

Claims

1. A process for the synthesis gas of biomass pyrolysis and gasification without pressurization reforming, comprising biomass drying, pyrolysis, gasification, combustion, steam generation and combustion air preheating processes; characterized in that: The heating, conversion and cooling of the synthetic raw gas (14) are carried out in multiple high-temperature gas-to-gas silicon carbide tube heat exchangers. The silicon carbide heat exchange tubes (23) are kept at a certain distance from each other and form a free space. The synthetic raw gas (14) is convectively heated to at least 1150°C from the outside using 1550°C heated flue gas (22). The flow rate of the synthetic gas in the silicon carbide heat exchange tube (23) reaches 85m / s. The synthetic raw gas (14) flows continuously through multiple silicon carbide heat exchange tubes (23). Each silicon carbide heat exchange tube (23) has a turbulent flow diversion edge (57) at the end. The synthetic raw gas (14) is introduced into the silicon carbide heat exchange tube (23) in a vortex rotating manner, generating a centrifugal force of 350N acting on the gas particles of the synthetic raw gas (14) with a mass of 1 gram.

2. A process for the synthesis gas of biomass pyrolysis gasification without pressurization reforming, characterized in that: In the biomass pyrolysis chamber (1) at an inclined angle, the biomass for pyrolysis, which falls under the action of gravity, is pushed upward from the bottom and pyrolyzed. The pyrolyzed biomass enters the biomass gasification chamber (16) at a downward inclination angle of 33 degrees for carbon gasification. The biomass in the biomass gasification chamber (16) slides downward only by gravity. The biomass in the biomass gasification chamber (16) accounting for at least 1 / 3 of the biomass mass fed into the biomass pyrolysis chamber (1) is transferred to the subsequent low-temperature moving grate combustion chamber (4).

3. The process for producing syngas from biomass pyrolysis and gasification without pressurization reforming 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, and a fuel layer at least 0.9 meters high is maintained in the biomass gasification chamber (16).

4. The process for producing syngas from biomass pyrolysis and gasification without pressurization reforming according to claim 2, characterized in that: After the biomass enters the biomass pyrolysis chamber (1), firstly, superheated steam (10) with a temperature of 850°C and a pressure of about 200-1000 Pa is blown in from the superheated steam introduction zone (13) located at the bottom according to the standard of about 6-9% of the biomass mass entering the biomass pyrolysis chamber (1), and then a mixed gas of 850°C superheated steam (10) and oxygen (11) (0-30°C) with a pressure of about 200-1000 Pa is blown in from the superheated steam and oxygen mixed gas introduction zone (15) located at the bottom according to the standard of about 18-23% of the biomass mass entering the biomass pyrolysis chamber (1) and 3% of the moisture content, at a ratio of about 2-2.5:

1.

5. The process for producing syngas from biomass pyrolysis and gasification without pressurization reforming according to claim 2, characterized in that: A mixed gas of superheated steam (10) and oxygen (11) at a temperature of 850° C. is blown into the biomass gasification chamber (16) according to the standard of 85-100% biomass and 0% moisture content. The oxygen weight proportion in the mixed gas is about 1-4%, and the oxygen weight proportion should also be adjusted according to the temperature in the biomass gasification chamber (16).

6. The process for producing syngas from biomass pyrolysis and gasification without pressurization reforming according to claim 2, characterized in that: The amount of biomass gasification residue transferred from the biomass gasification chamber (16) can be adjusted by a water-cooled feed roller (17) and forms a uniform fuel layer in the low-temperature moving grate combustion chamber (4), wherein the fuel layer has at least one rotatable sealing plate (18) which presses on the biomass fuel layer with its own weight.

7. The process for producing syngas from biomass pyrolysis and gasification without pressurization reforming according to claim 1, characterized in that: The silicon carbide heat exchange tubes (23) are butt-jointed with each other in the cast high temperature resistant partition wall (26) through silicon carbide connecting sleeves (55), and the silicon carbide connecting sleeves (55) are firmly connected to the tube ends of the silicon carbide heat exchange tubes (23) and the adhesive (56) made of ceramic fibers soaked in graphite paste.

8. The process for producing syngas from biomass pyrolysis and gasification without pressurization reforming 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 tube (23). When the synthetic raw gas (14) passes through the turbulent diversion edge (57) at high speed, turbulence will occur and vacuum, pressure pulses and similar cavitation jet effects will be generated in the free space.

9. The process for producing syngas from biomass pyrolysis and gasification without pressurization reforming according to claim 1, characterized in that: The multiple high-temperature gas-gas silicon carbide tube heat exchanger for reforming synthetic raw gas (14) comprises two parts, namely, an initial heat exchange unit (30) for reforming synthetic raw gas and a main heat exchange unit (31) for reforming synthetic raw gas. The initial heat exchange unit (30) for reforming synthetic raw gas and the main heat exchange unit (31) for reforming synthetic raw gas are interconnected via a heat-resistant ceramic transition channel (24). The synthetic raw gas (14) reaches a temperature of 1000°C in the initial heat exchange unit (30) for reforming synthetic raw gas, and then flows through a vortex generator (25) made of silicon carbide and located at the front end of the silicon carbide heat exchange tube (25) of the main heat exchange unit (31) for reforming synthetic raw gas, and enters the main heat exchange unit (31) for reforming synthetic raw gas with a high-speed vortex rotation.

10. The process for producing syngas from biomass pyrolysis and gasification without pressurization reforming according to claim 2, characterized in that: The pressures in the biomass pyrolysis chamber (1), the biomass gasification chamber (16) and the low-temperature moving grate combustion chamber (4) are always adjusted to the same set value.

Images