System for preparing green methanol from biomass

Abstract

The utility model discloses a system for preparing green methanol from biomass. The system mainly comprises a boiler power generation unit, an air separation unit, a gasification unit, a conversion unit, a desulfurization and decarbonization unit, a compression unit, a synthesis unit and a rectification unit. Pneumatic dense-phase conveying is adopted for biomass feeding of the gasification unit, CO2 of the desulfurization and decarbonization unit is selected as conveying gas, the biomass smashing particle size, the conveying density and the temperature and pressure of the conveying gas are controlled, and the biomass conveying stability is guaranteed. The gasification furnace adopts a waste heat boiler technology, sensible heat byproduct saturated steam of high-temperature synthesis gas can be recycled, purge gas of a synthesis unit is overheated to generate power to serve as system power, and the purge gas of the synthesis unit can be supplemented through byproduct superheated steam of a gas boiler when the electric quantity is insufficient. Biomass is adopted as an energy source instead of traditional fossil fuel, dependence on the fossil fuel can be remarkably reduced, carbon emission is reduced, the energy utilization efficiency is improved, the green electricity requirement is met, and a basis is provided for green methanol certification.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of biomass energy conversion technology especially relates to a green methanol system of biomass. BACKGROUND

[0002] In recent years, green shipping has become the transformation target of global shipping industry, and ships using green methanol as fuel will become a major trend in the future, and adopting biomass to make methanol is an important source of green methanol, and the transportation and gasification of biomass are key difficulties. At the same time, this project is also a coupling project of green electricity and biomass chemical industry.

[0003] At present, in the field of biomass energy conversion, gasification technology as a key unit for converting biomass into synthesis gas has attracted widespread attention, and existing biomass gasification technologies mainly include fixed bed, fluidized bed and entrained flow bed and other forms. However, each gasification technology has its own shortcomings. The shortcomings of fixed bed gasification technology are as follows: 1) the bulk density of biomass material is low, and special additives need to be added for briquetting treatment before entering the furnace. 2) the gasification efficiency is low and the heat transfer is uneven, which makes the synthesis gas mixed with a large amount of tar and solid material particles, increasing the complexity and investment cost of subsequent processing. 3) the synthesis gas contains a large amount of tar and solid material particles, which not only causes trouble to the synthesis gas washing unit, but also easily condenses at low temperature, causing blockage of pipe openings, valves, instruments, etc., making it difficult for the gasification equipment to operate stably for a long time. 4) the volatile content of biomass is extremely high (more than 60%), making it difficult to control the temperature of the fixed bed. The shortcomings of fluidized bed gasification technology are as follows: 1) in order to ensure the full reaction of the material, it is necessary to ensure the stability of the bed layer, and some fluidized bed technologies need heating medium such as sand, which makes the operation difficult, easy to wear the equipment, causes unstable production, and has high use cost. 2) the fluidized bed can only operate at normal pressure or slightly positive pressure, and the production capacity is small. 3) the synthesis gas contains a large amount of tar and solid material particles, which not only causes trouble to the synthesis gas washing unit, but also easily condenses at low temperature, causing blockage of pipe openings, valves, instruments, etc., making it difficult for the gasification equipment to operate stably for a long time. 4) the structure of fluidized bed gasifier is too complex, and the investment is huge. SUMMARY

[0004] The present application provides a green methanol system of biomass, which solves the technical problems of difficult biomass transportation, high chlorine, high potassium and sodium, and lack of electricity in remote areas in the prior art.

[0005] To solve the problem of biomass gasification, the patent provides the following solutions:

[0006] 1. In the process of biomass transportation, the gasification technology results in a low transportation density because biomass contains a large amount of fibrous material and the powder generally has low flowability. This patent uses carbon dioxide discharged from the desulfurization and decarbonization system as the transportation gas, which can reduce the ineffective utilization of N2.

[0007] 2. If solid slag discharge is used, the syngas will contain a large amount of tar and solid material particles, which will bring great difficulties to the water treatment system. Therefore, liquid slag discharge is selected this time. When the temperature in the combustion chamber is higher than the melting point of biomass ash, the tar and other organic matter react with oxygen to generate CO, H2 and CO2, thereby eliminating the problem of difficult water treatment.

[0008] 3. High chlorine content: The chloride ion content in biomass is generally between 0.5% and 1%. Temperature changes have a significant impact on the corrosion resistance of equipment and pipelines. Generally, as the temperature increases, the activity of chloride ions also increases, and the corrosive effect on equipment and pipelines intensifies accordingly. In addition, the microstructure of equipment materials also changes at high temperatures, reducing corrosion resistance. Therefore, a gasification pressure of 3.0 MPa is used, and the black water temperature in equipment such as the gasifier quench chamber and scrubbing tower is ensured to be <185℃. Furthermore, key equipment such as the gasifier, scrubbing tower, and lock hopper employ special material selection and design, which can reduce corrosion to a certain extent.

[0009] 4. High potassium and sodium content: The potassium and sodium content in biomass is greater than 10%. Potassium and sodium corrosion can be avoided from the following aspects: First, the combustion chamber of the gasifier adopts a water-cooled wall structure, which can prevent potassium and sodium from replacing the chromium in the refractory bricks, causing refractory brick erosion and shortening its service life; Second, the gasifier adopts a semi-waste boiler design. When designing the radiant waste boiler, it is ensured that the waste boiler section is in a high-temperature unit above 700℃, which can maximize the recovery of heat from high-temperature syngas and avoid the problem of ash sticking and slag blockage in the waste boiler caused by the low-temperature precipitation of potassium, sodium and alkali metals.

[0010] 5. The factory is located in a remote area with no electricity available. The system is equipped with a boiler and turbine unit. Steam produced by the gasification unit is superheated by the purge gas from the synthesis unit and then sent to the turbine to generate electricity for the system. This achieves both heat recovery and energy recovery.

[0011] 6. Biomass powder has low bulk density. Experiments have shown that processing biomass into specific forms before pulverizing it can increase its bulk density and reduce storage space.

[0012] This application provides a biomass-to-green methanol system, comprising:

[0013] The air separation unit transports the gasification medium to the gasification unit for the gasification and combustion of biomass powder.

[0014] A biomass processing unit processes biomass into specific forms;

[0015] a powder preparation unit for crushing the biomass into particles;

[0016] a powder conveying unit for conveying the biomass into the combustion chamber by dense phase pneumatic conveying;

[0017] a gasification unit, the combustion chamber of the gasification unit is provided with a water-cooled wall, and the gasification unit is designed as a semi-waste-heat boiler, and a waste-heat boiler is arranged in the high-temperature unit;

[0018] The biomass processing unit, the powder preparation unit, the powder conveying unit, and the gasification unit are sequentially connected, and the air separation unit is connected with the gasification unit.

[0019] In some embodiments, the oxygen purity in the air separation unit is 99.6%; the rod particle processed by the biomass processing unit has a length of ≤100 mm and an equivalent diameter of ≤60 mm; the biomass crushing particle size requirements are: a crushing particle size of ≤106 um, a mass fraction of 25-45%; a crushing particle size of ≤250 um, a mass fraction of 55-80%; a crushing particle size of ≤700 um, a mass fraction of 90-98%; a crushing particle size of ≤2500 um, a mass fraction of 100%; and a dense phase conveying density of 200-600 kg / m 3 ; the conveying gas temperature is 70-150°C, the conveying pressure difference is 1.5-3.0 MPa, and the gas type is carbon dioxide.

[0020] In some embodiments, the synthesis gas produced by the gasification unit sequentially enters a transformation unit, a desulfurization and decarburization unit, a compression unit, a synthesis unit, and a rectification unit to obtain green methanol.

[0021] In some embodiments, the system further comprises:

[0022] an energy storage cabinet connected with each unit to supply power to each unit;

[0023] a boiler and power generation unit including a boiler and a steam turbine, the gasification unit and the synthesis unit are respectively connected with a pipeline of the boiler, the boiler is connected with the steam turbine, and the steam turbine is connected with the energy storage cabinet.

[0024] In some embodiments, the high-temperature synthesis gas of the gasification unit enters the gasification furnace waste-heat boiler through a slag port, uses its own sensible heat to produce high-pressure saturated steam as a by-product, the saturated steam is heated in the boiler and then enters the steam turbine to generate power; the synthesis unit produces saturated steam as a by-product for use in the rectification unit, and the released purge gas is used as a heat source to heat the saturated steam in the boiler, and the steam turbine generates power.

[0025] In some embodiments, the boiler is a gas-fired boiler, the gas-fired boiler is embedded with a superheater, the fuel is the purge gas from the synthesis unit, the steam turbine is connected with the pipeline of the gas-fired boiler, and the superheated steam obtained by combustion is sent to the steam turbine to generate power.

[0026] In some embodiments, the boiler is a biomass boiler, which uses biomass to generate saturated steam, and the saturated steam is used to drive a steam turbine to generate electricity.

[0027] In some embodiments, the medium and low pressure steam produced by the conversion unit is used as a heat source to desorb gas from the desulfurization and decarbonization unit. When hydrogen is added to the system, the load of the conversion unit is reduced and the carbon-hydrogen ratio is adjusted to meet the requirements of the synthesis section.

[0028] In some embodiments, the carbon dioxide removed by the desulfurization and decarbonization unit is compressed and then sent to the gasification unit as a conveying gas to send the biomass powder to the gasification furnace; the sulfur removed by the desulfurization and decarbonization unit is sent to a sulfur recovery device.

[0029] In some embodiments, the biomass processing unit toasts the biomass.

[0030] The application has the following advantages:

[0031] By adjusting the particle size of the biomass, the dense phase conveying density, and the conveying gas flow rate, and adjusting the appropriate conveying pressure difference, the stable conveying of the biomass is ultimately ensured; CO2 is selected as the biomass conveying gas, which reduces the ineffective use of N2, changes the balance direction of the combustion reaction, moves towards the generation of carbon monoxide, increases the effective gas content, and thus improves the cold coal gas efficiency. The biomass gasification furnace adopts a waste boiler structure to recover the sensible heat of the high-temperature synthesis gas, and produces high-quality saturated or superheated steam as a byproduct, thereby improving the gasification thermal efficiency of the biomass.

[0032] After the biomass enters the gasification furnace, it is first preliminarily atomized and dispersed by the oxygen passing through the central oxygen passage, and then secondarily atomized by the oxygen passing through the annular oxygen passage, thereby enhancing the mixing effect of the biomass and the oxygen and making the biomass uniformly distributed in the combustion chamber, while receiving the radiant heat from the flame, the inner wall of the furnace, the high-temperature gas, the solid, and the heat of the backflow stream and the return stream (mainly composed of CO, H2, etc.), so that the biomass powder is uniformly heated. The biomass is instantaneously evaporated, and the biomass powder undergoes thermal cracking and releases volatile matter. The cracking products, volatile matter, and other flammable components are rapidly and completely combusted at high temperature and high oxygen concentration, releasing a large amount of heat.

[0033] The gasification furnace uses liquid slagging, which can ensure that the synthesis gas is not contaminated with tar. By controlling the amount of oxygen, the temperature of the combustion chamber is ensured to be greater than 50-100℃ higher than the ash melting point, so that the ash and slag enter the waste boiler unit in a liquid state. Boiler water is sprayed at the inlet of the waste boiler unit to rapidly solidify the ash and slag into a glass state, avoiding scaling on the waste boiler pipeline.

[0034] The gasification unit utilizes its own sensible heat to produce high-pressure saturated steam, and the purge gas of the synthesis unit is used as a heat source to send to the boiler to superheat the saturated steam, and then enter the steam turbine to generate power. The heat and energy of the gasification unit and the synthesis unit are reasonably utilized to achieve the purpose of energy saving and emission reduction. The composition of the purge gas of the synthesis unit is H2: 65-75%, CO: 4-10%, CO2: 5-15%, CH4: 4-10%, which is used as a heat source to enter the boiler and is combusted with air. The heat generated is used to superheat the high-pressure saturated steam produced by the gasification unit to a certain temperature, and then is sent to the steam turbine to generate power. The system relies on the steam turbine to generate power to meet the power consumption of each unit, thereby reducing the operating cost.

[0035] The relationship between the purge gas consumption and the power generation capacity is as follows:

[0036] The biomass consumption is 171t / h, the waste boiler of the gasification furnace produces steam 140t / h, the 140t / h steam is superheated to 230℃ and consumes the purge gas 9800Nm 3 , and the steam turbine generates power 49000KW·h.

[0037] Under normal conditions, the steam produced by the waste boiler of the gasification furnace after being superheated can be used to generate power for the system. However, when the steam production of the waste boiler of the gasification furnace is reduced due to scaling and other problems, in order to ensure the power generation capacity of the steam turbine, the biomass material of the gasification unit needs to be increased. Under the premise of not affecting the green methanol production, the amount of purge gas entering the boiler is increased, the amount of superheated steam entering the steam turbine is stabilized, and the power generation capacity of the steam turbine is unchanged.

[0038] The relationship between the biomass and the steam quantity is as follows:

[0039] The biomass consumption is 2570Kg, and the purge gas 2600Nm 3 can be obtained. The boiler can produce superheated steam 10t / h with a superheating degree of 230℃. At the same time, the biomass consumption is 171t / h, the waste boiler of the gasification furnace produces steam 130t / h, and the 130t / h steam is superheated to 230℃ and consumes the purge gas 9100Nm 3 , and the steam turbine generates power 49000KW·h.

[0040] When the steam production of the waste boiler of the gasification furnace is basically unchanged and the power consumption of the plant continues to increase, the amount of biomass entering the gasification furnace can be increased to increase the amount of purge gas entering the boiler and increase the amount of superheated steam entering the steam turbine.

[0041] The relationship between the biomass and the steam quantity is as follows:

[0042] The biomass consumption is 2570Kg, and the purge gas 2600Nm 3 can be obtained. The boiler produces superheated steam 10t / h with a superheating degree of 230℃. At the same time, the biomass consumption is 171t / h, the waste boiler of the gasification furnace produces steam 140t / h, and the 140t / h steam is superheated to 230℃ and consumes the purge gas 9800Nm 3The steam turbine generates 52500KW·h.

[0043] The change of the biomass is determined by the change of the steam generated by the waste heat boiler of the gasifier and the change of the total power consumption of the plant.

[0044] The waste heat boiler of the gasifier can also be designed to directly send the byproduct superheated steam into the steam turbine for power generation. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some of the embodiments of the present application.

[0046] Figure 1 A structural schematic diagram of a biomass methanol production system is provided in the present application. DETAILED DESCRIPTION

[0047] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0048] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative positional relationship, movement condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications also change accordingly.

[0049] In addition, the description of "first", "second", etc. in the present application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions of the various embodiments can be combined with each other, but must be based on the realization of the ordinary skilled in the art, and when the combination of the technical solutions contradicts each other or cannot be realized, it should be considered that the combination of the technical solutions does not exist and is not within the scope of protection claimed by the present application.

[0050] The embodiments of the present application provide a biomass green methanol production system, which solves the technical problems of large biomass transportation difficulty and remote plant construction site without power in the prior art.

[0051] The biomass mentioned in the technical solution includes but is not limited to straw, corn stalk, garbage, cow dung, wood and the like.

[0052] The analysis data of corn stalk as a representative are as follows

[0053] The following table is the analysis data of corn stalk in Inner Mongolia

[0054]

[0055]

[0056] As can be seen from the above table, the biomass represented by corn stalk has the following advantages when using the entrained-flow gasification:

[0057] 1. High volatile matter, the volatile matter in biomass can reach 74%-84%, which is beneficial to the gasification reaction;

[0058] 2. High reactivity, the reactivity of biomass is high, and the reactivity of biomass at 1000℃ can reach 100% in general;

[0059] 3. Low ash melting point, high silicon content, the ash content of straw is generally 5-10%, and the ash melting point is generally 1250℃; the ash content of forest wood is generally less than 1%, and the ash melting point is generally about 1400℃, and the silicon dioxide content is greater than 60%, which is beneficial to realize liquid slagging and form a glass body.

[0060] The technical solution in the embodiment of the application is to solve the above technical problems, and the general idea is as follows:

[0061] As shown in Figure 1 The application provides a biomass green methanol system, which comprises:

[0062] An air separation unit is configured to deliver a gasification medium to a gasification unit for gasification combustion of biomass powder;

[0063] A biomass processing unit is configured to process biomass into a specific form, and in the embodiment, the biomass processing unit processes the biomass into rod particles;

[0064] A powder preparation unit is configured to crush the biomass into particles;

[0065] A powder conveying unit is configured to use pneumatic dense phase conveying to feed the biomass into a combustion chamber;

[0066] Adjust the pipeline parameters, gas parameters and biomass parameters, calculate the pressure drop caused by the resistance of the fluid passing through the particle fixed bed, and control the pressure drop within a threshold value;

[0067] If the carrier gas is selected as N2, the biomass conveying density is kept constant, and because the density of N2 is low under the same temperature and pressure, the mass flow is small, and when conveying biomass of the same particle size, the minimum conveying speed of the biomass is reduced by 20%, and the conveying pressure difference is reduced by 15%, which is within the controllable range and is beneficial to the conveying system.

[0068] If the biomass conveying quality is increased by 20%, the biomass conveying density is increased by 20%, and other parameters are kept constant, then the minimum conveying speed of the biomass is increased by 30%, and the conveying pressure difference is increased by 35%, which exceeds the maximum allowable pressure difference range, and may cause the conveying pipeline to be blocked, which can be solved by increasing the amount of conveying gas to reduce the conveying pressure difference.

[0069] If the average particle size of the biomass particles is increased by 20%, other conditions are unchanged, the minimum conveying speed of the biomass is reduced by 5%, and the conveying pressure difference is increased by 2%, so that the pressure drop is within the controllable range.

[0070] If the biomass conveying pipe diameter is increased by 20%, other conditions are unchanged, the minimum conveying speed of the biomass is increased by 6%, and the conveying pressure difference is reduced by 2%, so that the pressure drop is within the controllable range.

[0071] The gasification unit, the combustion chamber of the gasification unit is provided with a water-cooled wall, and the gasification unit is designed as a semi-waste boiler, and the waste boiler is arranged in the high-temperature unit;

[0072] The biomass processing unit, the powder preparation unit, the powder conveying unit, and the gasification unit are sequentially connected, and the air separation unit and the gasification unit are connected.

[0073] The biomass processing unit can be selected to whether to roast the biomass. Roasting generally refers to a roasting process of biomass under low temperature and inert atmosphere, and the temperature is generally 200-400℃. Roasting can change the elemental composition and microstructure of biomass, so that the biomass is more easily crushed, and the crushing power consumption is saved. In the roasting process, the removal of water is due to the removal of free water, bound water and the cracking of hydroxyl groups in the side chains of hemicellulose and cellulose. The release of CH4 is mainly because the -CH3 functional groups in lignin are separated from the -CH2- in hemicellulose and cellulose and lignin. The release of CO2 gas is because the decarboxylation and decarbonylation reactions occur in the glucose uronic acid units in hemicellulose. The release of CO gas is mainly because the ether bond (C-O-C) in the phenylpropyl unit in lignin is broken and the xylan unit (C=O) in hemicellulose is cracked. The release of nitrogen-containing gas is mainly because N in the biomass raw material is decomposed into volatile matter, including light gases such as NH3, HCN, NO, by deamination, dehydration and decarboxylation. The gas mixture released by roasting can be used as fuel. The following figure is the analysis data of corn straw in Shanxi before and after roasting (roasting conditions: N2 atmosphere, 280℃ temperature, roasting for 20min):

[0074]

[0075] From the data in the above table, compared with the biomass raw material, the oxygen content of the biomass after baking treatment is reduced, the carbon content is increased, the fixed carbon content is increased, and the volatile matter is reduced, the calorific value of the biomass is increased, the hydrophobicity and grindability are improved, and the H / C and O / C are reduced, which are more conducive to the gasification of the biomass.

[0076] For the biomass raw material before and after baking used for gasification, the consumption and effective gas components designed are shown in the following table:

[0077]

[0078]

[0079] From the data in the table, it can be seen that the gasification of the biomass after baking can reduce oxygen consumption and increase effective gas components. The load of the biomass conveying section is reduced, and the power consumption of the biomass crushing section is reduced. Therefore, whether to bake the biomass can be selected in the biomass processing unit.

[0080] In the biomass powder processing unit, in order to reduce the transportation cost, the biomass is processed into rod particles at each collection point, and the rod particle specification is length ≤100mm, equivalent diameter ≤60mm. In this process, the density of the biomass is changed from 200kg / m 3 to 700kg / m 3 .

[0081] The biomass is stored in the raw material bin, and the biomass particles are weighed and fed into the crusher after being weighed by the weighing feeder. The dust-containing gas in the raw material bin is filtered and then discharged into the atmosphere by the exhaust fan. A compressed gas pipeline for back blowing is provided on the filter of the raw material bin. The biomass from the raw material bin is crushed into powder in the crusher and is conveyed by CO2 gas. Under normal conditions, the biomass crushing particle size is ≤106um, the mass fraction is 25-45%; the crushing particle size is ≤250um, the mass fraction is 55-80%; the crushing particle size is ≤700um, the mass fraction is 90-98%; and the crushing particle size is ≤2500um, the mass fraction is 100%. The crushed biomass passes through the powder filter and enters the powder storage bin.

[0082] Biomass flows into the biomass lock hopper from the biomass storage bin by gravity. When the biomass lock hopper reaches the required high level, it is isolated from all low pressure equipment, then pressurized until it is the same as the pressure of the biomass feed tank, at which time the pressure equalizing valve between the two tanks is opened. The biomass lock hopper is pressurized with carbon dioxide, which enters directly through the venting cone at the bottom of the tank and the flute in the middle of the tank. Biomass flows into the biomass feed tank from the biomass lock hopper by gravity. When all the biomass in the biomass lock hopper has entered the biomass feed tank, the shutoff valve at the bottom of the biomass lock hopper and the pressure equalizing valve between the two tanks are closed, isolating the biomass lock hopper from the high pressure system. Then, the biomass lock hopper is depressurized through the shutoff valve, discharging the pressure in the biomass lock hopper into the biomass storage filter. The operating pressure of the biomass lock hopper is 5.0-0.02 MPa (G) (the pressure of the gasifier is 3.0 MPa G), the pressure differential for conveying is 1.5-3.0 MPa, and the operating temperature is 80°C.

[0083] The biomass lock hopper is operated in a cycle of the above-described processes of discharging, pressurizing, discharging, and depressurizing, achieving the purpose of conveying biomass from the low pressure system to the high pressure system.

[0084] The oxygen from the air separation unit outside the boundary area enters the gasifier through the oxygen main, and passes through the flow regulating valve and the shutoff valve. The flow of the oxygen is measured, requiring temperature and pressure compensation. Part of the oxygen enters the gasifier through the outer ring channel of the process burner, and part of the oxygen enters the gasifier through the central channel. During the start-up stage, the oxygen is discharged to the atmosphere through the oxygen venting muffler to establish the oxygen flow.

[0085] In the combustion chamber of the gasifier, the carbon in the biomass and the oxygen, water, etc. undergo complex oxidation-reduction reactions, and a series of side reactions occur, generating a crude synthesis gas mainly composed of CO and H2. The non-combustible ash in the biomass and part of the carbon particles that have not completely reacted form ash slag. Therefore, the main components of the crude synthesis gas at the outlet of the combustion chamber of the gasifier include CO, H2, CO2, CH4, H2S, and water vapor, etc. A water-cooled wall is arranged in the pressure-resistant steel shell of the gasifier.

[0086] There is a downward flame below the process burner of the gasifier, forming a high temperature zone. The process burner is subjected to radiation from the high temperature zone, and the decrease in the strength of the metal at high temperatures and the scouring of the high-speed flowing biomass often cause wear and tear and thermal stress damage to the process burner. In order to protect the process burner, a water jacket is arranged at the end of the process burner, and the process burner cooling water circulates through the water jacket to cool the burner. The burner cooling water comes from the boiler water of the steam drum.

[0087] The crude synthesis gas, together with the molten liquid ash, leaves the gasifier combustion chamber and enters the radiant syngas cooler, which produces high-pressure saturated steam. The cooled crude synthesis gas enters the quench chamber, where it is cooled by the quench water pumped from the quench water tank. Most of the ash with larger particles in the crude synthesis gas is cooled and then sinks to the bottom of the quench chamber, and then enters the lock hopper, which is periodically discharged into the slag pool. This part of the ash is called coarse ash. The crude synthesis gas from the quench chamber enters the gas washing tower through the Venturi scrubber. The synthesis gas first enters the water at the bottom of the gas washing tower to wash off some fine ash. The synthesis gas, which is substantially free of solid particles, flows upward along the gas washing tower, and is directly contacted with the circulating ash water from the middle of the tower and the condensed liquid from outside the zone added at the top of the tower. The remaining solid particles are washed, and the dust content in the synthesis gas leaving the gas washing tower is <1 mg / Nm 3 A cyclone plate demister is installed at the top of the gas washing tower to remove the water mist entrained in the synthesis gas. The clean synthesis gas enters the shift work unit after leaving the gas washing tower.

[0088] The synthesis gas, after being heated in the heat exchanger with the high-temperature shift gas from the shift converter, enters the shift converter. The shift reaction occurs in the shift converter, and the CO reaches the appropriate proportion. The shift converter also produces medium-pressure saturated steam. The shift gas, after being cooled in the heat exchanger, enters the low-pressure steam waste heat boiler, which produces low-pressure saturated steam. The shift gas, after being heated in the boiler water heater, enters the organic sulfur hydrolysis tank, where the organic sulfur in the gas is converted to hydrogen sulfide under the action of the catalyst. The gas, after being heated in the desalted water heater, enters the shift gas cooler, which is cooled to a temperature of about 40°C. The gas, after being separated from the water in the shift gas separator, is sent to the desulfurization and decarburization unit. The desulfurization and decarburization unit can choose low-temperature methanol washing or MDEA method, and the appropriate method can be selected according to the specific circumstances of the project. The removed carbon dioxide is pressurized by the compressor and sent to the biomass powder conveying unit to stably convey the powder to the gasifier.

[0089] The synthesis gas from the purification unit enters the synthesis gas compressor, the compressed synthesis gas is cooled and separated from water, and then mixed with the circulating gas from the synthesis loop, and then enters the circulating compressor together, and then is sent to the synthesis system after compression. The synthesis gas compressor and the circulating gas compressor share a shaft. The synthesis gas entering the synthesis device is heated by heat exchange with the outlet reaction gas of the methanol synthesis tower in the gas-gas heat exchanger, and then enters the methanol synthesis tower. The outlet reaction gas is used to produce medium-pressure steam in the waste heat boiler, preheated in the gas-gas heat exchanger, and then enters the tower gas, and then is cooled to 40°C by the water cooler. The cooled gas enters the methanol separator for gas-liquid separation, and the separated gas is sent to the compressor circulation unit to increase the pressure and then returned to the methanol synthesis system. The byproduct steam is sent to the methanol rectification unit for use. The use of internally generated steam reduces dependence on external energy, thereby indirectly reducing the emission of greenhouse gases and other pollutants. The separated liquid crude methanol is sent to the rectification device after being flash evaporated at reduced pressure in the intermediate tank. The flash evaporated gas is used as fuel to heat the high-pressure saturated steam produced by the gasification unit. The heat and energy of the gasification unit and the synthesis unit are reasonably used to achieve the purpose of energy saving.

[0090] The crude methanol sent from the methanol synthesis enters the pre-rectification tower, where the light components are separated. The gas evaporated from the top of the tower is condensed in the pre-tower condenser to condense methanol, water, and part of the light components. The condensed liquid enters the pre-tower reflux tank, and the non-condensable gas enters the light component cooler for further cooling. The non-condensable gas from the light component cooler is used as fuel gas in the boiler house, and the condensed liquid is returned to the pre-rectification tower as reflux liquid. The methanol liquid from the bottom of the pre-rectification tower is pressurized by the methanol feed pump and sent to the pressurized rectification tower. The methanol vapor evaporated from the top of the tower enters the condensing reboiler, and the condensing heat of the methanol vapor is used as the heat source for the atmospheric rectification tower. The refined methanol liquid from the condensing reboiler enters the pressurized tower reflux tank. Part of the refined methanol is pressurized by the pressurized tower reflux pump and sent to the pressurized rectification tower, and the rest is cooled to 40°C by the refined methanol cooler and sent to the refined methanol intermediate tank. The methanol liquid from the bottom of the pressurized rectification tower is sent to the lower part of the atmospheric rectification tower. The methanol vapor evaporated from the tower is condensed by the atmospheric tower condenser and then enters the atmospheric tower reflux tank. The refined methanol is pressurized by the atmospheric tower reflux pump, and part of it is injected into the atmospheric tower reflux, and the rest is sent to the refined methanol intermediate tank. The product of the refined methanol intermediate tank is sent to the methanol storage after passing the test.

[0091] The raw material is corn straw. The cost and economic preliminary accounting of the above process is shown in the following table,

[0092]

[0093]

[0094] From the table, the cost of biomass to green methanol is 1503 yuan / ton, and the comprehensive energy consumption of biomass to green methanol per unit product is 1232 kgce / t. The energy consumption limit of 1380 kgce / t is executed in the energy consumption limit of methanol, ethylene glycol and dimethyl ether per unit product (GB29436-2023) 1 level index, and the comprehensive energy consumption of biomass to methanol is better than 1 level index.

[0095] Although the preferred embodiments of the present application have been described, those skilled in the art can make further changes and modifications to these embodiments once they know the basic inventive concept. Therefore, the appended claims are intended to be interpreted as including all the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0096] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application also intends to include these modifications and variations.

Claims

1. A system for producing green methanol from biomass, characterized in that, It comprises: an air separation unit for conveying gasification medium to a gasification unit for gasification combustion of biomass powder; a biomass processing unit for processing biomass into rod particles; a powder preparation unit for crushing biomass into particles; a powder conveying unit for pneumatic dense phase conveying of biomass into a combustion chamber; a gasification unit, the combustion chamber of which is provided with a water-cooled wall, and the gasification unit is designed with a waste boiler, which is arranged in a high-temperature unit; the biomass processing unit, the powder preparation unit, the powder conveying unit and the gasification unit are connected in sequence, and the air separation unit is connected with the gasification unit.

2. The system for producing green methanol from biomass according to claim 1, wherein, The synthesis gas produced by the gasification unit enters a transformation unit, a desulfurization and decarburization unit, a compression unit, a synthesis unit and a rectification unit in sequence to obtain green methanol.

3. The system for producing green methanol from biomass according to claim 2, wherein, It further comprises: an energy storage cabinet connected with each unit to supply power to each unit; a boiler and power generation unit comprising a boiler and a steam turbine, the gasification unit and the synthesis unit being connected with the boiler pipeline respectively, the boiler being connected with the steam turbine, and the steam turbine being connected with the energy storage cabinet.

4. The system for producing green methanol from biomass according to claim 3, wherein, The high-temperature synthesis gas of the gasification unit enters the waste boiler of the gasification furnace through the slag port, and uses its own sensible heat to produce high-pressure saturated steam as a by-product, which is heated to a superheated state in the boiler and then enters the steam turbine to generate power; the synthesis unit produces saturated steam as a by-product for use in the rectification unit, and the released purge gas is used as a heat source to heat the saturated steam in the boiler to a superheated state, and the steam turbine is used to generate power.

5. The system for producing green methanol from biomass according to claim 4, wherein, The boiler is a gas-fired boiler with an embedded superheater, and the fuel is the purge gas from the synthesis unit, which is connected with the pipeline of the gas-fired boiler, and the superheated steam generated by combustion is sent to the steam turbine to generate power.

6. The system for producing green methanol from biomass according to claim 3, wherein, The boiler is a biomass boiler, which uses biomass to produce saturated steam in the boiler, which is then superheated in the steam turbine to generate power.

7. The system for producing green methanol from biomass according to claim 2, wherein, The carbon dioxide removed by the desulfurization and decarburization unit is pressurized by a compressor and then conveyed to the gasification unit as a conveying gas to send the biomass powder to the gasification furnace; the sulfur removed by the desulfurization and decarburization unit is conveyed to a sulfur recovery device.

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