A pyrolysis bio-oil fractional condensation device and method with self-circulation of cooling medium

Abstract

The present invention relates to a pyrolysis bio-oil fractional condensation device and method with self-circulation of a cooling medium, including a primary condensation system, a secondary condensation system, and a cooling medium temperature self-regulating heat exchange system; the primary condensation system uses the temperature-adjusted cooling medium to directly exchange heat with the pyrolysis volatiles on the one hand, so that the macromolecular tar therein is condensed, and on the other hand, heats and keeps the condensed tar warm, and uses a rotating mechanism to push and scrape the tar to prevent the tar from sticking; the secondary condensation system directly exchanges heat between the spraying liquid and the uncondensed volatiles after the primary condensation for secondary condensation; the cooling medium temperature self-regulating heat exchange system realizes the self-circulation and self-balance of the mass flow and energy flow of the cooling medium by integrating the heat absorption in the biomass raw material feeding and drying process, the heat release in the condensation of volatiles, and the heat absorption in the cooling of pyrolysis coke, and solves the problem of the independent operation of the condensation device in the mobile biomass pyrolysis system.

Description

Technical Field

[0001] The present invention relates to the technical field of biomass pyrolysis condensation, and in particular to a pyrolysis bio-oil fractional condensation device and method with self-circulation of a cooling medium. Background Art

[0002] The preparation of bio-oil by biomass pyrolysis liquefaction is an important form of biomass energy utilization and is also a biomass-based engineering technology route with a simple process and easy large-scale implementation. The system equipment for biomass pyrolysis is mainly divided into four parts: (1) a raw material feeding device; (2) a pyrolysis reactor; (3) a bio-oil condensation and collection device; and (4) a biochar condensation and collection device. Among them, the bio-oil condensation and collection device is related to the yield and components of the target product bio-oil, and its structure also has a great influence on the basic properties of bio-oil (including moisture content, viscosity, corrosiveness, calorific value, etc.). Fractional condensation is a method of separating bio-oil into two or more bio-oil products with different compositions and stable properties, such as macromolecular tar and wood vinegar, by using the different boiling points of various components of bio-oil itself through an on-line separation method. Both of these products have good prospects for industrial application. Tar can be used as a raw material for preparing high-quality activated carbon or carbon black, and wood vinegar is a green organic agricultural fertilizer.

[0003] At present, the bio-oil fractional condensation device mainly uses a condensation method of multi-stage spray direct condensation or shell-and-tube indirect condensation in series, which is also an easy-to-implement technical means. The applicant's research found that in the low-temperature condensation section, both the spray direct condensation method and the shell-and-tube indirect condensation method are relatively mature, and are also relatively simple in terms of mechanism and industrial promotion. However, the difficulty of the fractional condensation process lies in the condensation of tar in the high-temperature section. The tar components are mainly some macromolecular oligomers, which have characteristics such as high viscosity and easy wall sticking. When using spray direct condensation, due to its poor fluidity, the transportation and atomization effects are poor. When using shell-and-tube indirect condensation, due to its high viscosity and easy wall sticking, it is easy to block the heat exchanger channel, and an adhesion layer is formed on the heat transfer tube wall, greatly reducing the heat transfer efficiency. Therefore, it is extremely important to develop a new device for pyrolysis bio-oil fractional condensation to collect tar and wood vinegar.

[0004] In addition, the mobile biomass pyrolysis liquefaction system is one of the current mainstream development directions. Its essence is to require the entire pyrolysis system, including the feeding, pyrolysis reactor, condensation, and coke collection devices, to be placed on a mobile source. Therefore, new requirements are put forward for the bio-oil condensation device. The condensation device of the centralized biomass pyrolysis system generally uses water as a cold source or cooling medium, but this solution is not applicable to the mobile biomass pyrolysis liquefaction system. Summary of the Invention

[0005] Aiming at the shortcomings of the existing technology, the present invention provides a pyrolysis bio-oil fractional condensation device and method with self-circulating cooling medium, realizing the independent operation of the condensation device of the mobile biomass pyrolysis system.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A pyrolysis bio-oil fractional condensation device with self-circulating cooling medium, comprising a primary condensation system, a secondary condensation system and a cooling medium temperature self-regulating heat exchange system;

[0008] The structure of the primary condensation system includes a tar condensation device, which adopts a direct heat exchange structure, enabling the high-temperature pyrolysis volatiles to directly exchange heat with the cooling medium and then condense to form tar; the structure of the secondary condensation system includes a spray chamber, which also adopts a direct heat exchange structure, allowing the uncondensed volatiles after the primary condensation to directly exchange heat with the spray liquid and undergo secondary condensation.

[0009] The structure of the cooling medium temperature self-regulating heat exchange system includes a temperature regulating mixer and several heat exchangers. The first heat exchanger uses a part of the cooling medium heated up by the primary condensation system as a heat source for drying biomass raw materials. The second heat exchanger uses the cooling medium cooled down by the first heat exchanger as a cold source for cooling the spray liquid. The third heat exchanger uses another part of the cooling medium heated up by the primary condensation system as a cold source for cooling the pyrolysis coke generated during the pyrolysis process. At the same time, the cooling medium heated up by the second heat exchanger and the third heat exchanger is respectively introduced into the temperature regulating mixer for mixing and then supplied to the tar condensation device to form a circulation loop.

[0010] Its further technical solution is as follows:

[0011] The structure of the tar condensation device includes a hollow jacketed pipe, inside which there is a hollow rotating shaft. A cavity for the volatiles to flow is formed between the hollow rotating shaft and the hollow jacketed pipe. Both ends of the hollow jacketed pipe are respectively provided with a tube-side inlet and a tube-side outlet communicating with the cavity. An axial cavity is formed inside the hollow rotating shaft, and its two ends are respectively provided with a shaft-side inlet and a shaft-side outlet.

[0012] The temperature regulating mixer is provided with a high-temperature inlet, a low-temperature inlet and a medium-temperature outlet; the medium-temperature outlet is connected to the tube-side inlet and the shaft-side inlet respectively through parallel pipelines. After the tube-side outlet and the shaft-side outlet are connected in parallel, they are respectively connected to the medium-side inlets of the first heat exchanger and the third heat exchanger through a three-way valve. The medium-side outlet of the first heat exchanger is connected to the medium-side inlet of the second heat exchanger. The medium-side outlet of the third heat exchanger is connected to the high-temperature inlet, and the low-temperature inlet is connected to the medium-side outlet of the second heat exchanger.

[0013] A plurality of groups of blades are arranged axially on the hollow rotating shaft. A plurality of each group of blades are evenly distributed along the circumference. A scraper is connected to the tip of each blade, and the scraper abuts against the inner wall of the hollow jacket tube.

[0014] The blade has a hollow structure, and a radial cavity is formed therein, and the radial cavity communicates with the axial cavity.

[0015] A shunt device for evenly distributing air flow is provided at the gas inlet of the spray chamber. Its structure includes a louver type flow equalizing plate, and the louver type flow equalizing plate includes a plurality of blades evenly and symmetrically distributed along the circumferential and height directions; an inflow pipe is connected upstream of the louver type flow equalizing plate, and the inflow pipe is connected to the gas outlet of the tar condensation device.

[0016] The second heat exchanger is a shell-and-tube heat exchange structure, and a spray liquid inlet and outlet are provided on its shell. The spray liquid inlet is connected to the conduction pipe at the bottom of the spray chamber, and the spray liquid outlet is connected to the spray head at the top of the spray chamber through a pipeline.

[0017] The third heat exchanger is a shell-and-tube heat exchange structure, and a gaseous pyrolysis coke inlet and a liquid pyrolysis coke outlet are provided on its shell; the first heat exchanger adopts a shell-and-tube heat exchanger, and a conveying mechanism for conveying biomass raw materials is provided in its shell.

[0018] A volatile matter inlet and a tar collection box are provided on the hollow jacket tube.

[0019] A method for a pyrolysis bio-oil fractional condensation device with self-circulation of a cooling medium includes a self-circulation process of the cooling medium and a secondary condensation process of the volatile matter;

[0020] The secondary condensation process is as follows:

[0021] The primary condensation system uses the temperature-adjusted cooling medium to directly exchange heat with the pyrolysis volatile matter on the one hand, so that the large-molecule tar therein condenses, and on the other hand, heats and keeps the temperature of the condensed tar, and at the same time uses a rotary device to push and scrape the tar to prevent it from sticking;

[0022] The secondary condensation system directly exchanges heat between the spray liquid and the uncondensed volatile matter after the primary condensation to achieve further condensation;

[0023] The self-circulation process of the cooling medium is as follows:

[0024] The cooling medium heated up through the primary condensation process, a part of it is used as a cold source for pyrolysis coke cooling, and the cooled cooling medium is further used as a cold source to cool the spray liquid for recycling; another part is used as a heat source for drying and heating the biomass raw materials. After cooling the spray liquid and heating the biomass raw materials, the two parts of the cooling medium are mixed to form the temperature-adjusted cooling medium for the primary condensation, forming a cycle;

[0025] Among them, the temperature of the spray liquid used to cool the uncondensed volatile matter is 20 - 50 °C;

[0026] The temperature of the cooling medium after heat exchange with the spray liquid is 50 - 100 °C;

[0027] The temperature of the cooling medium after heat exchange with the pyrolytic char is 300 - 350 °C;

[0028] The temperature of the temperature - adjusted cooling medium is 150 - 220 °C.

[0029] The beneficial effects of the present invention are as follows:

[0030] (1) By integrating the heat absorption in the biomass raw material feeding and drying process, the heat release in the volatile matter condensation, and the heat absorption in the pyrolytic char cooling, the cooling medium of the present invention realizes the self - circulation and self - balance of the mass flow and energy flow of the cooling medium, and solves the problem of the independent operation of the condensation device in the mobile biomass pyrolysis system.

[0031] (2) Under the heat preservation of the hollow jacket pipe, the hollow rotating shaft, the blades and the self - cleaning function of the scraper of the tar condensation device of the present invention, effective cooling and collection of macromolecular tar without sticking to the wall can be achieved.

[0032] (3) The diverter of the spray chamber with a diverter of the present invention has a unique quadrangular frustum louver structure, which can prevent the water flow in the spray chamber from flowing into the diverter and make the volatile matter gas evenly distributed on the cross - section of the spray chamber. Brief Description of the Drawings

[0033] Figure 1 It is a schematic structural diagram of the condensation device of the present invention.

[0034] Figure 2 It is a schematic installation structure diagram of the hollow rotating shaft, the blades and the scraper of the condensation device of the invention.

[0035] Figure 3 It is a structural diagram of the diverter of the condensation device of the invention.

[0036] In the figure: 1, volatile matter inlet; 2, tar condensation device; 3, hollow jacketed pipe; 4, hollow rotating shaft; 5, tar collection box; 6, diverter; 7, spray chamber; 8, demister; 9, pyrolysis gas outlet pipe; 10, conduction pipe; 11, second heat exchanger; 12, wood vinegar liquid heat exchange coil; 13, spray head; 14, cooling medium inlet; 15, cooling medium outlet; 16, temperature regulating mixer; 17, low temperature inlet; 18, high temperature inlet; 19, medium temperature outlet; 20, axial side inlet; 21, tube side inlet; 22, tube side outlet; 23, axial side outlet; 24, three-way valve; 25, first heat exchanger; 26, third heat exchanger; 27, axial cavity; 28, radial cavity; 29, scraper; 30, louver type flow equalizing plate; 31, rib plate; 32, blade; 33, inlet pipe. Detailed implementation mode

[0037] The following combines the accompanying drawings to illustrate the detailed implementation mode of the present invention.

[0038] As Figure 1 shown, the pyrolysis bio-oil fractional condensation device with self-circulating cooling medium in this embodiment includes a primary condensation system, a secondary condensation system, and a cooling medium temperature self-regulating heat exchange system;

[0039] The structure of the primary condensation system includes a tar condensation device 2, which adopts a direct heat exchange structure to directly exchange heat between high-temperature pyrolysis volatiles and the cooling medium and then condenses to form tar; the structure of the secondary condensation system includes a spray chamber 7, which adopts a direct heat exchange structure to directly exchange heat between the uncondensed volatiles after primary condensation and the spray liquid to cause secondary condensation;

[0040] The structure of the cooling medium temperature self-regulating heat exchange system includes a temperature regulating mixer 16 and several heat exchangers. The first heat exchanger 25 uses a part of the cooling medium heated by the primary condensation system as a heat source for drying biomass raw materials. The second heat exchanger 11 uses the cooling medium cooled by the first heat exchanger 25 as a cold source for cooling the spray liquid. The third heat exchanger 26 uses another part of the cooling medium heated by the primary condensation system as a cold source for cooling the pyrolysis coke generated during the pyrolysis process. At the same time, the cooling medium heated by the second heat exchanger 11 and the third heat exchanger 26 is respectively introduced into the temperature regulating mixer 16 for mixing and then supplied to the tar condensation device 2 to form a circulation loop.

[0041] In the above embodiment, the structure of the tar condensation device 2 includes a hollow jacketed pipe 3, inside which there is a hollow rotating shaft 4. A cavity for the flow of volatiles is formed between the hollow rotating shaft 4 and the hollow jacketed pipe 3. The two ends of the hollow jacketed pipe 3 are respectively provided with a tube side inlet 21 and a tube side outlet 22 communicating with the cavity. As Figure 2 shown, an axial cavity 27 is formed inside the hollow rotating shaft 4, and its two ends are respectively provided with an axial side inlet 20 and an axial side outlet 23.

[0042] Specifically, the volatile matter flows in the cavity, and at the same time, a cooling medium is introduced into the cavity, so that the volatile matter directly exchanges heat with the cooling medium, cooling the large-molecule tar in the volatile matter to condense it.

[0043] The axial cavity 27 is also used to introduce a cooling medium to provide a heat preservation condition for the tar to prevent it from cooling and adhering to the hollow jacket tube 3 or the shaft.

[0044] In the above embodiment, the temperature adjustment mixer 16 is provided with a high-temperature inlet 18, a low-temperature inlet 17 and a medium-temperature outlet 19; the medium-temperature outlet 19 is respectively connected to the tube-side inlet 21 and the shaft-side inlet 20 through a parallel pipeline, and the tube-side outlet 22 and the shaft-side outlet 23 are connected in parallel and then respectively connected to the medium-side (cooling medium) inlets of the first heat exchanger 25 and the third heat exchanger 26 through a three-way valve 24. The medium-side (cooling medium) outlet of the first heat exchanger 25 is connected to the medium-side (cooling medium) inlet of the second heat exchanger 11, the medium-side (cooling medium) outlet of the third heat exchanger 26 is connected to the high-temperature inlet 18, and the low-temperature inlet 17 is connected to the medium-side (cooling medium) outlet of the second heat exchanger 11.

[0045] In the above embodiment, the hollow jacket tube 3 is provided with a volatile matter inlet 1 and a tar collection box 5 communicating with its internal cavity.

[0046] In order to improve the fluidity of the tar, as Figure 2 shown, a plurality of groups of blades 32 are axially arranged on the hollow rotating shaft 4, and each group of blades 32 is evenly distributed with a plurality of blades along the circumference. A scraper 29 is connected to the tip of each blade 32, and the scraper 29 abuts against the inner wall of the hollow jacket tube 3. The volatile matter flows in from the volatile matter inlet 1, flows through the gaps between the blades and generally flows axially, exchanging heat with the condensing medium to condense. The hollow rotating shaft 4 is driven by a driving device to rotate, and the blades 32 rotate accordingly, pushing the tar formed by condensation to flow, and finally converging into the tar collection box 5. At the same time, the scraper 29 is used to scrape off the tar that may adhere to the inner wall of the hollow jacket tube 3 to prevent it from adhering.

[0047] As a preferred mode, as Figure 2 shown, each group of blades 32 includes two blades, and each blade is tangentially deflected by a certain angle with respect to the hollow rotating shaft 4, and the two blades are symmetrically arranged on the hollow rotating shaft 4.

[0048] As a preferred mode, the longitudinal section of the blade of the blade 32 is in a trapezoidal structure.

[0049] As a preferred mode, the scraper 29 is in a sheet-like structure and extends axially for a certain length to improve the scraping effect.

[0050] To increase the heat exchange area, improve the heat preservation performance, and further enhance the fluidity of tar, the paddle 32 is configured as a hollow structure with a radial cavity 28 formed therein, and the radial cavity 28 communicates with the axial cavity 27. Specifically, the radial cavity 28 and the axial cavity 27 can be connected through small through-holes provided on the hollow rotating shaft 4, so that during the rotation of the hollow rotating shaft 4, the cooling medium flows from the axial cavity 27 into the radial cavity 28, thereby increasing the heat exchange area and meeting the heat preservation requirements for condensing tar.

[0051] A hollow sandwich layer is formed on the wall of the hollow jacketed pipe 3 to improve the heat insulation performance from the external environment, and thus improve the heat preservation performance of the tar condensation device 2.

[0052] As a preferred method, for tar with a relatively high viscosity, under the heat preservation effect of the hollow jacketed pipe 3, the hollow rotating shaft 4, and the paddle 32, it is pushed forward by the paddle 32 with the scraper 29 and flows into the tar collection box 5.

[0053] In the above embodiment, in order to improve the gas flow uniformity and thus enhance the secondary condensation effect, a flow divider 6 for uniforming the gas flow is provided at the gas inlet of the spray chamber 7, and its structure includes a louvered flow equalizing plate 30. As Figure 3 shown, the louvered flow equalizing plate 30 includes a plurality of blades evenly and symmetrically distributed along the circumferential and height directions; an inlet pipe 33 is connected upstream of the louvered flow equalizing plate 30, and the inlet pipe 33 is connected to the gas outlet of the tar condensation device 2.

[0054] As a specific implementation manner, the louvered flow equalizing plate 30 can be configured as a quadrangular pyramid structure, and blades arranged in sequence along the height direction are respectively provided on its four side surfaces, and adjacent side surfaces are fixedly strengthened by rib plates 31.

[0055] Specifically, the inlet pipe 33 is parallel to the gas inflow direction, and the louvered flow equalizing plate 30 is perpendicular to the inlet pipe 33. The blades of the louver are at a certain angle with the spray direction of the spray liquid to prevent the spray liquid from flowing into the flow divider 6.

[0056] As a specific implementation manner, as Figure 1 shown, the second heat exchanger 11 is a shell-and-tube heat exchange structure, and a spray liquid inlet and outlet are provided on its shell. The spray liquid inlet is connected to the conduction pipe 10 at the bottom of the spray chamber 7, and the spray liquid outlet is connected to the spray head 13 at the top of the spray chamber 7 through a pipeline.

[0057] Specifically, the spray liquid uses wood vinegar liquid, and the medium-side passage of the second heat exchanger 11 uses a wood vinegar liquid heat exchange coil 12, and cooling medium inlets 14 and cooling medium outlets 15 are respectively provided at both ends thereof.

[0058] Specifically, a demister 8 is provided at the top of the spray chamber 7, and its outlet is connected to a pyrolysis gas outlet pipe 9. The uncondensed volatile components from the tar condensation device 2 enter the spray chamber 7 through the shunt 6 from its gas outlet. After being cooled by the spray liquid through spraying, secondary condensation occurs, and at the same time, the water-soluble phase of wood vinegar liquid is collected. The water-soluble phase of wood vinegar liquid is sent to the wood vinegar liquid heat exchange coil 12 of the second heat exchanger 11 through the conduction pipe 10 below the spray chamber 7. After heat exchange with the cooling medium, it is transported to the spray head 13 again through a pipeline from the top of the second heat exchanger 11 to achieve circulating spraying.

[0059] As a specific implementation manner, as Figure 1 shown, the third heat exchanger 26 is a shell-and-tube heat exchange structure, and a gaseous pyrolysis coke inlet and a liquid pyrolysis coke outlet (not shown in the figure) are provided on its shell, where the heating coke is the substance generated during the biomass pyrolysis process;

[0060] As a specific implementation manner, the first heat exchanger 25 adopts a shell-and-tube heat exchanger, and a conveying mechanism for conveying biomass raw materials is provided in its shell. The biomass raw materials are heated and dried by the cooling medium, saving the preheating energy consumption before pyrolysis.

[0061] Specifically, the above-mentioned conveying mechanism is a spiral feeder, and the cooling medium flows through the tube to achieve indirect heat exchange with the spiral feeder.

[0062] A method for a pyrolysis bio-oil fractional condensation device with self-circulation of the cooling medium in this embodiment includes a self-circulation process of the cooling medium and a secondary condensation process of the volatile components;

[0063] The secondary condensation process is as follows:

[0064] The primary condensation system uses the temperature-adjusted cooling medium to directly exchange heat with the pyrolysis volatile components on the one hand, so that the macromolecular tar is condensed, and on the other hand, the condensed tar is heated and kept warm. At the same time, a rotary device is used to push and scrape the tar to prevent it from sticking;

[0065] The secondary condensation system directly exchanges heat between the spray liquid and the uncondensed volatile components after the primary condensation to achieve further condensation;

[0066] The self-circulation process of the cooling medium is as follows:

[0067] The cooling medium heated up through the primary condensation process, a part of which is used as a cold source for pyrolysis coke cooling, and the cooled cooling medium is further used as a cold source to cool the spray liquid for recycling; another part is used as a heat source for drying and heating the biomass raw materials. After the two parts of the cooling medium have cooled the spray liquid and heated the biomass raw materials, they are mixed to form the temperature-adjusted cooling medium for primary condensation, forming a cycle;

[0068] Among them, the temperature of the spraying liquid used to cool the uncondensed volatile matter is 20 - 50°C;

[0069] The temperature of the cooling medium after heat exchange with the spraying liquid is 50 - 100°C;

[0070] The temperature of the cooling medium after heat exchange with the pyrolytic char is 300 - 350°C;

[0071] The temperature of the cooling medium after temperature adjustment is 150 - 220°C.

[0072] The specific process is as follows:

[0073] The volatile matter condensation process is as follows: The volatile matter entering from the pyrolysis volatile matter inlet 1 of the tar condensation device 2 is cooled by the cooling medium after temperature adjustment (temperature is 150 - 220°C). Under this action, the macromolecular tar condenses. Its viscosity is relatively large. Under the heat preservation of the hollow jacketed pipe 3, the hollow rotating shaft 4 and the paddle 32, it is pushed forward by the paddle 32 with a scraper 29 and flows into the tar collection box 5; The uncondensed volatile matter directly enters the louver type diverter 6 of the spray heat exchange and condensation wood vinegar liquid system from the outlet. Under the action of the louver type flow equalizing plate 30, the volatile matter gas flow is evenly distributed across the entire cross-section of the spray chamber 7. Under the direct heat exchange action (temperature is 20 - 50°C) of the cooling wood vinegar liquid passing through the spray head 13, secondary condensation occurs. The collected aqueous phase wood vinegar liquid flows into the shell of the second heat exchanger 11 through the conduction pipe 10. The aqueous phase wood vinegar liquid exchanges heat and cools with the cooling medium in the wood vinegar liquid heat exchange coil 12 and then sprays through the spray head 13 to cool the pyrolysis volatile matter. The cooled pyrolysis gas flow passes through the demister 8 to remove the aerosol and then flows out through the pyrolysis gas outlet pipe 9;

[0074] The flow process of the cooling medium loop is as follows: One part of the cooling medium in the tar condensation device 2 flows in from the tube side inlet 21, directly exchanges heat with the pyrolysis volatiles in the high-temperature section, and then flows out through the tube side outlet 22. The other part flows in from the shaft side inlet 20 into the hollow rotating shaft 4, flows out through the shaft side outlet 23, and converges into the three-way valve 24. One of the paths passes through the No. 3 heat exchanger 26 as the cold source for cooling the pyrolytic coke during the pyrolysis process. After the cooling medium is heated, it enters the temperature regulating mixer 16 from the high-temperature inlet 18. At this time, the temperature of this part of the cooling medium reaches 300 - 350 °C. Another path passes through the No. 1 heat exchanger 25 as the drying heat source for the biomass raw material. After the cooling medium cools down the raw material during drying, it enters the wood vinegar liquid heat exchange coil 12 of the No. 2 heat exchanger 11 from the cooling medium inlet 14 as the cold source for the wood vinegar liquid. After heat exchange, it is heated up and enters the temperature regulating mixer 16 through the low-temperature inlet 17 from the cooling medium outlet 15. At this time, the temperature of this part of the cooling medium reaches 50 - 100 °C. The high- and low-temperature cooling media are mixed in the temperature regulating mixer 16, and the temperature of the temperature-regulated cooling medium is 150 - 220 °C. It is fed into the shaft side inlet 20 and the tube side inlet 21 respectively through the parallel-connected pipelines from the medium-temperature outlet 19, and serves as the cold source and heat preservation medium for condensing the macromolecular tar in the tar condensation device 2.

[0075] The above-mentioned cooling medium uses media such as water.

[0076] A pyrolysis bio-oil fractional condensation device and method with self-circulation of the cooling medium according to the present invention solve the problem that the condensation device of the mobile biomass pyrolysis system can operate independently, and adopts a high- and low-temperature two-stage fractional condensation system. By integrating the heat absorption during the drying process of the biomass raw material, the heat release during the condensation of the volatiles, and the heat absorption during the cooling of the pyrolytic coke, the self-circulation and self-balance of the mass flow and energy flow of the cooling medium are realized, achieving the purpose of multi-stage energy utilization.

[0077] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should be regarded as the protection scope of the present invention.

Claims

1. A method for fractional condensation of pyrolytic bio-oil with self-circulation of cooling medium, characterized in that, The devices used include a primary condensation system, a secondary condensation system, and a heat exchange system for self-regulating the temperature of the cooling medium; The structure of the primary condensation system includes a tar condensation device (2), which adopts a direct heat exchange structure to directly exchange heat between the high-temperature pyrolysis volatiles and the cooling medium and then condenses to form tar; the structure of the secondary condensation system includes a spray chamber (7), which adopts a direct heat exchange structure to directly exchange heat between the uncondensed volatiles after primary condensation and the spray liquid for secondary condensation; The structure of the heat exchange system for self-regulating the temperature of the cooling medium includes a temperature-regulating mixer (16) and several heat exchangers. The first heat exchanger (25) uses a part of the cooling medium heated up by the primary condensation system as a heat source for drying biomass raw materials. The second heat exchanger (11) uses the cooling medium cooled down by the first heat exchanger (25) as a cold source for cooling the spray liquid. The third heat exchanger (26) uses another part of the cooling medium heated up by the primary condensation system as a cold source for cooling the pyrolytic coke generated during the pyrolysis process. At the same time, the cooling media heated up by the second heat exchanger (11) and the third heat exchanger (26) are respectively introduced into the temperature-regulating mixer (16) for mixing and then supplied to the tar condensation device (2) to form a circulation loop; The method includes a self-circulation process of the cooling medium and a secondary condensation process of the volatiles; The secondary condensation process is as follows: The primary condensation system uses the temperature-regulated cooling medium to directly exchange heat with the pyrolysis volatiles on the one hand to condense the large-molecule tar therein, and on the other hand to heat and keep warm the condensed tar. At the same time, a rotary device is used to push and scrape the tar to prevent it from sticking; the secondary condensation system uses the spray liquid to directly exchange heat with the uncondensed volatiles after primary condensation to achieve further condensation; The self-circulation process of the cooling medium is as follows: A part of the cooling medium heated up by the primary condensation process is used as a cold source for cooling the pyrolytic coke. After being used for cooling, the cooling medium is further used as a cold source to cool the spray liquid for recycling; another part is used as a heat source for heating and drying the biomass raw materials. After the spray liquid is cooled and the biomass raw materials are heated, the two parts of the cooling medium are mixed to form the temperature-regulated cooling medium for the primary condensation to form a circulation; Among them, the temperature of the spray liquid used for cooling the uncondensed volatiles is 20 - 50 °C; The temperature of the cooling medium after heat exchange with the spray liquid is 50 - 100 °C; The temperature of the cooling medium after heat exchange with the pyrolytic coke is 300 - 350 °C; The temperature of the temperature-regulated cooling medium is 150 - 220 °C.

2. The method according to claim 1, characterized in that, The structure of the tar condensation device (2) includes a hollow jacketed pipe (3) with a hollow rotating shaft (4) disposed therein. A cavity for the flow of volatile components is formed between the hollow rotating shaft (4) and the hollow jacketed pipe (3). The two ends of the hollow jacketed pipe (3) are respectively provided with a tube-side inlet (21) and a tube-side outlet (22) that communicate with the cavity. An axial cavity (27) is formed within the hollow rotating shaft (4), and an axial-side inlet (20) and an axial-side outlet (23) are respectively provided at its two ends.

3. The method according to claim 2, characterized in that, The temperature regulating mixer (16) is provided with a high-temperature inlet (18), a low-temperature inlet (17), and a medium-temperature outlet (19). The medium-temperature outlet (19) is connected to the tube-side inlet (21) and the axial-side inlet (20) respectively through parallel pipelines. After the tube-side outlet (22) and the axial-side outlet (23) are connected in parallel, they are respectively connected to the medium-side inlets of the first heat exchanger (25) and the third heat exchanger (26) through a three-way valve (24). The medium-side outlet of the first heat exchanger (25) is connected to the medium-side inlet of the second heat exchanger (11). The medium-side outlet of the third heat exchanger (26) is connected to the high-temperature inlet (18). The low-temperature inlet (17) is connected to the medium-side outlet of the second heat exchanger (11).

4. The method according to claim 3, characterized in that, A plurality of groups of blades (32) are arranged axially on the hollow rotating shaft (4). Each group of blades (32) is evenly distributed in a circumferential direction with a plurality of them. A scraper (29) is connected to the tip of each blade (32), and the scraper (29) abuts against the inner wall of the hollow jacketed pipe (3).

5. The method according to claim 4, characterized in that, The blade (32) has a hollow structure, and a radial cavity (28) is formed therein. The radial cavity (28) communicates with the axial cavity (27).

6. The method according to claim 3, characterized in that, A flow divider (6) for evenly distributing the gas flow is provided at the gas inlet of the spray chamber (7). Its structure includes a louver-type flow equalizing plate (30). The louver-type flow equalizing plate (30) includes a number of blades that are evenly and symmetrically distributed in the circumferential and height directions. An inlet pipe (33) is connected upstream of the louver-type flow equalizing plate (30), and the inlet pipe (33) is connected to the gas outlet of the tar condensation device (2).

7. The method according to claim 3, characterized in that, The second heat exchanger (11) has a shell-and-tube heat exchange structure. The shell of the second heat exchanger (11) is provided with a spray liquid inlet and outlet. The spray liquid inlet is connected to a conduction pipe (10) at the bottom of the spray chamber (7), and the spray liquid outlet is connected to a spray head (13) at the top of the spray chamber (7) through a pipeline.

8. The method according to claim 3, characterized in that, The third heat exchanger (26) has a shell-and-tube heat exchange structure. The shell of the third heat exchanger (26) is provided with a gaseous pyrolysis coke inlet and a liquid pyrolysis coke outlet. The first heat exchanger (25) is a shell-and-tube heat exchanger, and a conveying mechanism for conveying biomass raw materials is provided inside its shell.

9. The method according to claim 2, characterized in that, The hollow jacketed pipe (3) is provided with a volatile component inlet (1) and a tar collection box (5).

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