A steam explosion device and method for realizing rapid heating and rapid pressure relief of biomass

Abstract

The present application belongs to the technical field of processing equipment, and relates to a steam explosion device and method for realizing rapid heating and rapid pressure relief of biomass, which comprises a cooking pot, an explosion discharge unit, a screw feeder, an anti-back spray valve and a steam supply unit. Through the setting of the screw feeder, the present application can make the material form a dense plug inside the screw feeder, and make the plug enter the inside of the cooking pot through the anti-back spray valve, which not only avoids the influence of external air on the heat transfer efficiency of steam to the material, but also avoids the leakage of steam in the cooking pot, so that the heating of the material is more uniform, thereby improving the heat utilization efficiency of the steam explosion process. At the same time, the steam is vertically and uniformly injected downward through the multiple air holes on the annular pipe, which further makes the material heat more uniformly, improves the effect of steam explosion treatment, avoids the increase of energy consumption due to insufficient or excessive local heating, and thereby ensures the subsequent conversion efficiency.

Description

Technical Field

[0001] This invention belongs to the field of processing equipment technology, and relates to a steam explosion device and method for achieving rapid heating and rapid depressurization of biomass. Background Technology

[0002] Steam explosion is a green, environmentally friendly, efficient, low-energy, and economical new biomass pretreatment technology. It primarily involves the instantaneous release of steam molecules that have penetrated plant tissues, converting the steam's internal energy into mechanical energy that acts on the intercellular layers of biomass tissues. This allows for the improvement of the physicochemical properties and structure of biomass with relatively little energy. Because it avoids the secondary pollution problems of chemical treatments and solves the problem of low efficiency in biological treatments, it is one of the most promising pretreatment technologies in the field of biomass conversion.

[0003] Currently, the steam explosion device used for steam explosion of materials includes a cooking tank. The upper feed inlet of the cooking tank is equipped with a feed hopper, and the lower part of the cooking tank is equipped with a steam explosion discharge unit. The steam inlet of the cooking tank is connected to a steam supply unit. In use, the feed hopper is opened to add materials into the cooking tank, the feed hopper is closed, and then the steam supply unit is used to supply steam into the cooking tank. After the cooking tank reaches the preset pressure and is maintained for a certain period of time, the steam explosion discharge unit is opened to perform steam explosion, thus completing the steam explosion treatment of the materials.

[0004] However, during each feeding process, outside air can easily mix into the digester. When the steam contains air, the air, as a non-condensable gas, will accumulate at the steam-biomass gas solid-phase interface to form a gas film. This gas film increases thermal resistance and causes mass transfer obstacles, resulting in uneven heating of the material. This affects the permeability and uniformity of steam to the material, which not only reduces the effect of steam explosion treatment, but may also increase energy consumption and affect subsequent conversion efficiency due to insufficient or excessive heating in some areas. Summary of the Invention

[0005] The purpose of this invention is to provide a steam explosion device and method for achieving rapid heating and depressurization of biomass, which can prevent air from mixing into the cooking tank, making the material heated more evenly and improving the effect of steam explosion treatment.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0007] A steam explosion device for rapidly heating and depressurizing biomass includes a cooking tank, the outlet of which is equipped with an explosion discharge unit, and further includes:

[0008] The screw feeder, with its outlet connected to the feed inlet of the digester, is used to create a dense plug of material inside the digester to prevent air from entering.

[0009] An anti-backflow valve is installed at the outlet of the screw feeder to prevent air from entering the cooking tank.

[0010] The steam supply unit includes a steam boiler and at least one annular pipe. The inlet of the steam boiler is connected to a water source, and the outlet of the steam boiler is connected to the annular pipe. The annular pipe is horizontally arranged inside the cooking tank, and the lower part of the annular pipe has multiple air holes along its circumference to guide the steam to be injected vertically and evenly downward.

[0011] The invention is further characterized by:

[0012] The blasting discharge unit includes a quick-opening ball valve, a check valve, and a cyclone separator connected in sequence. The quick-opening ball valve is located at the outlet of the cooking tank and is used to open and close the outlet of the cooking tank. The check valve is used to prevent air from entering the cooking tank from the cyclone separator. The cyclone separator is used to separate steam and materials.

[0013] A Laval nozzle is installed between the quick-opening ball valve and the check valve, with its two ends connected to the quick-opening ball valve and the check valve, respectively.

[0014] The steam boiler is equipped with a first valve at the inlet, which can open the inlet of the steam boiler to introduce water. The steam boiler is equipped with a second valve at the outlet, which can open the outlet of the steam boiler to deliver steam to the cooking tank.

[0015] The steam boiler is equipped with a first exhaust valve. One end of the first exhaust valve is connected to the steam boiler, and the other end of the first exhaust valve is connected to the atmosphere. The first exhaust valve is used to exhaust the steam boiler. The cooking tank (1) is equipped with a second exhaust valve. One end of the second exhaust valve is connected to the cooking tank, and the other end of the second exhaust valve is connected to the atmosphere. The second exhaust valve is used to exhaust the cooking tank.

[0016] A steam explosion method for achieving rapid heating and depressurization of biomass includes the following steps:

[0017] The number of air replacements by steam is calculated using the air content and final air value in the cooking tank.

[0018] The replacement operation is carried out according to the number of times the steam replaces the air. Steam is supplied to the cooking tank using the steam supply unit until the pressure inside the cooking tank reaches the preset value. The mixture of steam and air inside the cooking tank is then emptied. When the last replacement operation is performed, the mixture of steam and air, as well as the condensate, is discharged from the cooking tank.

[0019] Start the screw feeder and feed the material into the screw feeder inlet. After the material forms a dense plug inside the screw feeder, stop the screw feeder, open the automatic response switch of the anti-backflow valve, start the screw feeder, and use the material plug to push open the anti-backflow valve and enter the cooking tank.

[0020] Steam is supplied to the cooking tank using a steam supply unit until the pressure inside the cooking tank reaches a preset value and is maintained for a certain period of time.

[0021] Open the blasting discharge unit and use it to cause steam explosion of the material to obtain steam-exploded material.

[0022] The specific formula for calculating the number of air replacements by steam is as follows:

[0023]

[0024] In the formula, n is the number of replacements, x2 is the air content in the cooking tank (100% when no replacement is performed), x1 is the final air value, P1 is the initial pressure in the cooking tank, and P2 is the preset pressure.

[0025] The duration of maintenance is 3 to 5 minutes.

[0026] The steam explosion device and method for rapidly heating and depressurizing biomass according to the present invention have the following advantages:

[0027] This invention, through the design of the screw feeder, enables the material to form a dense plug inside the screw feeder. This plug then enters the digester through the anti-backflow valve, preventing outside air from entering the digester and affecting the heat transfer efficiency of the steam to the material. It also prevents steam leakage from the digester, resulting in more uniform heating of the material and improving the heat utilization efficiency of the steam explosion process. At the same time, the steam is guided vertically and evenly downward through multiple vents on the annular pipe, further ensuring more uniform heating of the material and improving the effect of steam explosion treatment. This avoids increased energy consumption due to insufficient or excessive heating in certain areas, thus ensuring the subsequent conversion efficiency. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0029] Figure 2 This is a bottom view of the annular tube structure of the present invention.

[0030] Figure 3 This is a schematic diagram of the structure of the Laval nozzle of the present invention.

[0031] Figure label:

[0032] 1. Cooking tank; 2. Steam boiler; 3. Screw feeder; 4. Anti-backflow valve; 5. Annular pipe; 6. Laval nozzle; 601. Contraction section; 602. Throat; 603. Expansion section; 7. Conveying pipe; 8. Quick-opening ball valve; 9. Cyclone separator; 10. Check valve; 11. First valve; 12. Second valve; 13. First exhaust valve; 14. Second exhaust valve; 15. Support; 16. Air vent. Detailed Implementation

[0033] The technical solutions of the present invention will now be described clearly and in detail with reference to the accompanying drawings. In the description of the embodiments of the present invention, unless otherwise stated, " / " indicates "or," for example, A / B can mean A or B. "And / or" in the text is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone. Furthermore, in the description of the embodiments of the present invention, "multiple" refers to two or more. The terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature.

[0034] like Figure 1 , Figure 2As shown, this invention provides a steam explosion device for rapid heating and depressurization of biomass, including a cooking tank 1, a screw feeder 3, an anti-backflow valve 4, and a steam supply unit. The outlet of the cooking tank 1 is equipped with an explosion discharge unit. The outlet of the screw feeder 3 is connected to the inlet of the cooking tank 1. The screw feeder 3 is used to form a dense plug inside the material to prevent air from entering the cooking tank 1. The anti-backflow valve 4 is located at the outlet of the screw feeder 3. The anti-backflow valve 4 is used to prevent air from entering the cooking tank 1 and to prevent steam from leaking from the inlet of the cooking tank 1. The steam supply unit includes a steam boiler 2 and at least one annular pipe 5. The inlet of the steam boiler 2 is connected to a water source. The annular pipe 5 is horizontally arranged inside the cooking tank 1. The outlet of the steam boiler 2 is connected to the annular pipe 5. The lower part of the annular pipe 5 has multiple air holes 16 along its circumference to guide the steam to be injected vertically and uniformly downward. This invention, through the arrangement of the screw feeder 3, enables the material to form a dense plug inside the screw feeder 3, and allows the plug to enter the digester 1 through the anti-backflow valve 4. This not only prevents outside air from entering the digester 1 and affecting the heat transfer efficiency of steam to the material, but also prevents steam leakage inside the digester, resulting in more uniform heating of the material and thus improving the heat utilization efficiency of the steam explosion process. At the same time, the steam is guided vertically and uniformly downward by multiple air holes 16 on the annular pipe 5, further making the material heated more uniformly, improving the effect of steam explosion treatment, and avoiding increased energy consumption due to insufficient or excessive local heating, thereby ensuring the subsequent conversion efficiency.

[0035] like Figure 2 As shown, the diameter of the pores 16 is 1mm to 5mm, and the number of pores 16 is usually 10 to 20.

[0036] When there are multiple annular tubes 5, the multiple annular tubes 5 are evenly arranged along the vertical direction.

[0037] Among them, the cooking tank 1 is a vertical pressure vessel with a volume of 5m³. 3 ~30m 3 With a length-to-diameter ratio of 3:2, it can withstand pressure of over 5MPa.

[0038] like Figure 1 As shown, the top of the anti-backflow valve 4 is a conical structure, and the bottom diameter is larger than the outlet diameter of the screw feeder 3, so that the conical structure at the top of the anti-backflow valve 4 can be inserted into the outlet of the screw feeder 3 to block air from entering or steam from leaking.

[0039] like Figure 1As shown, the inlet of the steam boiler 2 is equipped with a first valve 11, which can open the inlet of the steam boiler 2 to introduce water and close the inlet of the steam boiler 2 after use. The outlet of the steam boiler 2 is equipped with a second valve 12, which can open the outlet of the steam boiler 2 to supply steam to the cooking tank 1 and close the outlet of the steam boiler 2 after supplying steam. A steam pipe is provided between the steam boiler 2 and the annular pipe 5. One end of the steam pipe is connected to the outlet of the steam boiler 2, and the other end of the steam pipe passes through the steam inlet of the cooking tank 1 and is connected to the annular pipe 5. The steam pipe is sealed to the steam inlet of the cooking tank 1.

[0040] like Figure 1 As shown, a first exhaust valve 13 is provided on the steam boiler 2. One end of the first exhaust valve 13 is connected to the steam boiler 2, and the other end of the first exhaust valve 13 is connected to the atmosphere. The first exhaust valve 13 is used to exhaust air from the steam boiler 2 to remove air from the steam boiler 2. A second exhaust valve 14 is provided on the cooking tank 1. One end of the second exhaust valve 14 is connected to the cooking tank 1, and the other end of the second exhaust valve 14 is connected to the atmosphere. The second exhaust valve 14 is used to exhaust air from the cooking tank 1 to remove air from the cooking tank 1.

[0041] like Figure 1 As shown, the blasting discharge unit includes a quick-opening ball valve 8, a check valve 10, and a cyclone separator 9 connected in sequence. The quick-opening ball valve 8 is located at the outlet of the cooking tank 1 and is used to open and close the outlet of the cooking tank 1. The check valve 10 is used to prevent air from entering the cooking tank from the cyclone separator. The cyclone separator 9 is used to separate steam and materials.

[0042] The quick-opening ball valve 8 has a diameter of 10-30cm and can withstand pressures above 10MPa and high-temperature steam at 350℃. It is either a pneumatic or solenoid valve with an opening / closing time of less than 5 seconds. The check valve is a swing check valve, horizontally installed on the conveying pipe 7. It closes by gravity to prevent air from entering from the outside. To avoid material entering the conveying pipe 7, the right-angle sections of the pipe should be designed with rounded corners or a certain degree of curvature.

[0043] like Figure 1 , Figure 3 As shown, a Laval nozzle 6 is installed between the quick-opening ball valve 8 and the check valve 10. The two ends of the Laval nozzle 6 are connected to the quick-opening ball valve 8 and the check valve 10, respectively. The Laval nozzle 6 is used to accelerate the ejected steam and materials, making them go from subsonic speed to sonic speed, or even supersonic speed, thereby increasing the ejection rate of steam and materials during steam explosion and depressurization, increasing the mechanical work done by the liquid water during adiabatic expansion, and causing more severe damage to the structure of the processed materials, thus improving the effect of steam explosion.

[0044] like Figure 1As shown, the Laval nozzle 6 and the cyclone separator 9 are connected by a delivery pipe 7, and a check valve 10 is installed on the delivery pipe 7.

[0045] like Figure 3 As shown, the Laval nozzle 6 consists of a contraction section 601, a throat 602, and an expansion section 603. High-pressure steam and materials enter from the contraction section 601, pass through the throat 602, and then escape from the expansion section 603. This process causes the airflow velocity to change with the cross-sectional area of ​​the Laval nozzle 6, thereby achieving speeds from subsonic to sonic, and even exceeding sonic speeds.

[0046] This invention also provides a steam explosion method for achieving rapid heating and rapid depressurization of biomass, using the above-mentioned apparatus, comprising the following steps:

[0047] The number of air replacements by steam is calculated using the air content and final air value in the cooking tank 1.

[0048] The replacement operation is carried out according to the number of times the steam replaces the air. Steam is supplied to the cooking tank 1 using the steam supply unit until the pressure in the cooking tank 1 reaches the preset value. The mixture of steam and air in the cooking tank 1 is then emptied. When the last replacement operation is performed, the mixture of steam and air and condensate in the cooking tank 1 are discharged.

[0049] Start the screw feeder 3 and add the material from the inlet of the screw feeder 3. After the material forms a dense plug inside the screw feeder 3, stop the screw feeder 3, open the automatic response switch of the anti-backflow valve 4, start the screw feeder 3, and use the material plug to push open the anti-backflow valve 4 and enter the cooking tank 1.

[0050] Steam is supplied to the cooking tank 1 using a steam supply unit until the pressure inside the cooking tank 1 reaches a preset value and is maintained for a certain period of time.

[0051] Open the blasting discharge unit and use it to cause steam explosion of the material to obtain steam-exploded material.

[0052] The specific formula for calculating the number of air replacements using steam is as follows:

[0053]

[0054] In the formula, n is the number of replacements, x2 is the air content in the cooking tank 1 (100% before replacement), x1 is the final air value (the final value to which the air content needs to be reduced), P1 is the initial pressure in the cooking tank 1, and P2 is the preset pressure (the steam explosion pressure). This represents the sampling error.

[0055] The duration of maintenance is 3 to 5 minutes.

[0056] The specific steps of this invention during operation are as follows:

[0057] 1) Before replacement, the air content x2 in the digester 1 is 100%, and the final air value V2 is 0.1%, meaning the air content needs to be reduced to 0.1%. The initial pressure P1 in the digester 1 is 0.1 MPa, and the preset pressure P2 is 3 MPa, meaning the required steam explosion pressure is 3 MPa. Calculate the number of replacement cycles n using the above formula:

[0058]

[0059] 2) At the initial moment, close all valves of the device, start the steam boiler 2, and use the first exhaust valve 13 to vent the air in the steam boiler 2 until the pressure of the steam boiler 2 rises to 3MPa.

[0060] 3) Considering steam condensation, the air content in the cooking tank 1 can be reduced to 0.1% by repeating the air replacement method 4 times. Open the second valve 4 to supply steam into the cooking tank 1 until the pressure in the cooking tank 1 reaches the preset value of 3MPa. Close the second valve 4 and open the second valve 12 to purge the steam and air mixture in the cooking tank 1. Repeat this 3 times and then perform the 4th steam replacement air operation. Keep everything else the same. Open the quick-opening ball valve 8 to purge the steam and air mixture and condensate in the cooking tank 1. Close the quick-opening ball valve 8.

[0061] 4) Start the screw feeder 3 and add the material from the inlet of the screw feeder 3. After the material forms a dense plug in the screw feeder 3, stop the screw feeder 3, open the automatic response switch of the anti-backflow valve 4, start the screw feeder 3, and use the plug to push open the anti-backflow valve 4 to enter the digester 1. The conical structure at the top of the anti-backflow valve 4 will break the plug and drop it into the digester 1. After the material is injected into the digester 1, close the automatic response switch of the anti-backflow valve 7 and the screw feeder 3.

[0062] 5) Use the steam supply unit to supply steam to the cooking tank 1. The superheat of the steam is 10℃~30℃. Maintain the steam for 3min~5min until the pressure inside the cooking tank 1 reaches the preset value.

[0063] 6) Open the quick-opening ball valve 8. The gas-liquid-solid mixture generated after the steam explosion quickly passes through the quick-opening ball valve 8, is accelerated by the Laval nozzle 6, and flows through the check valve 15 to complete the separation of steam and material in the cyclone separator 9.

[0064] 7) The high-temperature exhaust gas leaving the cyclone separator 9 has a low solid content, which allows for good heat recovery, and the steam explosion waste has a low water content, which facilitates subsequent processing.

[0065] 8) Since biomass generates a very small amount of CO2 and CH4 gas after each steam explosion, the content of non-condensable gas will gradually accumulate as the number of treatments increases, affecting the steam heat transfer efficiency. Usually, after 10 to 20 steam explosions, the non-condensable gas in the cooking tank 1 needs to be replaced by air replacement. The mixed gas in the air replacement process also needs to be heat recovered to save energy.

[0066] The steam explosion device and method for rapidly heating and depressurizing biomass according to the present invention have the following other advantages:

[0067] First, this invention reduces air in the cooking tank, allowing biomass to heat up in a near-pure steam environment. The air content is reduced from 100% to 0.1%, theoretically increasing the condensation heat transfer rate by 30% to 60%. Compared with traditional steam explosion devices, the advantages are: shorter processing time for the same processing capacity; and greater processing capacity for the same processing time.

[0068] Second, the present invention uses a ring pipe as a steam distributor to enhance the convection between steam and materials, thereby improving the heat transfer rate.

[0069] Third, the present invention uses a Laval nozzle to accelerate the ejection rate of materials and gases during steam explosion and depressurization, and increases the mechanical work done by the liquid water during adiabatic expansion, so that the structure of the treated material is more severely damaged and the treatment effect is better.

[0070] Fourth, the present invention uses superheated steam as the processing medium, which can effectively avoid the waste of latent heat and prevent steam from corroding pipelines, extend the service life of the device, and reduce maintenance costs.

[0071] It is understood that this invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of this invention. Furthermore, under the teachings of this invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of this invention. Therefore, this invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this invention are within the protection scope of this invention.

Claims

1. A steam explosion method for achieving rapid heating and rapid depressurization of biomass, characterized in that, A steam explosion device for rapidly heating and depressurizing biomass is employed, comprising: A cooking tank (1) is provided with a burst discharge unit at its outlet; The screw feeder (3) has its outlet connected to the feed inlet of the digester (1). The screw feeder (3) is used to form a dense plug inside the material to prevent air from entering the digester (1). An anti-backflow valve (4) is installed at the outlet of the screw feeder (3) to prevent air from entering the cooking tank (1); The steam supply unit includes a steam boiler (2) and at least one annular pipe (5). The inlet of the steam boiler (2) is connected to a water source, and the outlet of the steam boiler (2) is connected to the annular pipe (5). The annular pipe (5) is horizontally arranged inside the cooking tank (1). The lower part of the annular pipe (5) is provided with a plurality of air holes (16) along its circumference to guide the steam to be sprayed vertically and evenly downward. The steam explosion method for achieving rapid heating and depressurization of biomass includes the following steps: The number of times steam replaces air is calculated using the air content and final air value in the cooking tank (1); The replacement operation is carried out according to the number of times the steam replaces the air. Steam is supplied to the cooking tank (1) using the steam supply unit until the pressure inside the cooking tank (1) reaches the preset value. The mixture of steam and air inside the cooking tank (1) is emptied. When the last replacement operation is carried out, the mixture of steam and air and condensate inside the cooking tank (1) are discharged. Start the screw feeder (3), add the material from the inlet of the screw feeder (3), and stop the screw feeder (3) after the material forms a dense plug in the screw feeder (3). Open the automatic response switch of the anti-backflow valve (4), start the screw feeder (3), and use the plug to push open the anti-backflow valve (4) and enter the cooking tank (1). Steam is supplied to the cooking tank (1) using a steam supply unit until the pressure inside the cooking tank (1) reaches a preset value and is maintained for a certain period of time. Open the explosive discharge unit and use it to steam-explode the material to obtain steam-exploded material. The specific formula for calculating the number of air replacements by steam is as follows: In the formula, n is the number of replacements, x2 is the air content in the cooking tank (1), which is 100% when no replacement is performed, x1 is the final air value, P1 is the initial pressure in the cooking tank (1), and P2 is the preset pressure.

2. The steam explosion method for achieving rapid heating and rapid depressurization of biomass according to claim 1, characterized in that, The blasting discharge unit includes a quick-opening ball valve (8), a check valve (10), and a cyclone separator (9) connected in sequence. The quick-opening ball valve (8) is located at the outlet of the cooking tank (1) and is used to open and close the outlet of the cooking tank (1). The check valve (10) is used to prevent air from entering the cooking tank (1) from the cyclone separator (9). The cyclone separator (9) is used to separate steam and material.

3. The steam explosion method for achieving rapid heating and rapid depressurization of biomass according to claim 2, characterized in that, A Laval nozzle (6) is provided between the quick-opening ball valve (8) and the check valve (10), and the two ends of the Laval nozzle (6) are connected to the quick-opening ball valve (8) and the check valve (10) respectively.

4. The steam explosion method for achieving rapid heating and rapid depressurization of biomass according to claim 1, characterized in that, The steam boiler (2) is provided with a first valve (11) at its inlet, which can open the inlet of the steam boiler (2) to introduce water. The steam boiler (2) is provided with a second valve (12) at its outlet, which can open the outlet of the steam boiler (2) to deliver steam to the cooking tank (1).

5. The steam explosion method for achieving rapid heating and rapid depressurization of biomass according to claim 1, characterized in that, The steam boiler (2) is provided with a first exhaust valve (13), one end of which is connected to the steam boiler (2) and the other end of which is connected to the atmosphere. The first exhaust valve (13) is used to exhaust the steam boiler (2). The cooking tank (1) is provided with a second exhaust valve (14), one end of which is connected to the cooking tank (1) and the other end of which is connected to the atmosphere. The second exhaust valve (14) is used to exhaust the cooking tank (1).

6. The steam explosion method for achieving rapid heating and rapid depressurization of biomass according to claim 1, characterized in that, The maintenance time is 3 to 5 minutes.

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