CN111286349A - A twin-screw pyrolysis reactor based on the internal circulation of pyrolysis carbon to enhance heat transfer - Google Patents

Abstract

The invention discloses a double-helix pyrolysis reactor based on pyrolysis carbon internal circulation enhanced heat transfer, belonging to the technical field of renewable energy utilization, wherein: the double-helix pyrolysis reactor takes a horizontal cylindrical outer spiral roller as a main body, a pyrolysis gas outlet is arranged at the upper end of the left part of the double-helix pyrolysis reactor, a feed inlet is arranged at the upper end of the right part of the double-helix pyrolysis reactor, a pyrolysis carbon collecting box is arranged at the lower end of the right part of the double-helix pyrolysis reactor, and three support frames are arranged at the lower part of an electric heating device and used for; two coaxial rotating screws with opposite blade spiral directions, namely an outer screw and an inner screw, are arranged in the inner spiral roller, a pyrolytic carbon exchange port is arranged at the left side of the inner spiral roller, a carbon circulation port is arranged at the lower end of the right side of the inner spiral roller, and a pyrolytic carbon collection box is arranged at the lower end of the right side of the outer spiral roller; the invention utilizes the spiral structure to convey materials, improves the heat transfer performance of the device, increases the biomass treatment capacity per unit volume and provides a solution for the heat source problem of the mobile pyrolysis device.

Description

A twin-screw pyrolysis reactor based on the internal circulation of pyrolysis carbon to enhance heat transfer

technical field

The invention provides a double-spiral pyrolysis reactor based on the internal circulation of pyrolysis carbon to enhance heat transfer, which belongs to the technical field of renewable energy utilization.

Background technique

Biomass energy density is low, the distribution is relatively scattered, and its collection, transportation and storage costs are high, which greatly limits the development and utilization of biomass energy. Biomass pyrolysis is a potential biomass energy utilization technology, but the existing biomass pyrolysis processes are all stationary processes, resulting in half of the biomass pyrolysis process cost being consumed in the process of raw material collection, storage and transportation. If biomass raw materials can be converted into bio-oil on-site in a small pyrolysis device that is easy to move, and then the bio-oil can be transported to intermediate processing nodes for large-scale centralized refining, the collection radius of biomass raw materials can be effectively reduced. Fundamentally solve the problem of high cost of biomass raw material collection and transportation.

Biomass pyrolysis reactor is the core component of biomass pyrolysis technology. Existing pyrolysis reactors mainly include the following two types:

1. Direct heating type pyrolysis reactors: mainly include fluidized bed reactors, double fluidized bed reactors, rotating cone reactors, etc. (commonly used for rapid pyrolysis). Biomass is directly mixed with high-temperature heat carrier for pyrolysis, which has good heat transfer performance and large processing capacity, but requires a large amount of carrier gas, high energy consumption, and more impurities in the product, and poor material adaptability.

2. Partition heating type pyrolysis reactor: mainly includes rotary kiln reactor, spiral reactor, etc. (commonly used for slow pyrolysis). Using an external heat source to heat the reactor, the reactor transfers heat to the biomass, the material adaptability is good, and the solid residence time is adjustable, but the heat transfer performance is poor and it is difficult to enlarge.

SUMMARY OF THE INVENTION

Technical problem: In order to solve the above problems, the present invention provides a device for the catalytic pyrolysis of biomass based on the internal circulation of pyrolysis carbon. The device combines direct heating and partition heating to achieve medium-speed pyrolysis of biomass. , improve heat transfer performance, improve material adaptability, and increase biomass processing capacity.

Technical scheme: a kind of double-spiral pyrolysis reactor based on the internal circulation of pyrolysis carbon to strengthen heat transfer of the present invention is realized as follows:

The double-spiral pyrolysis reactor takes a horizontal cylindrical outer spiral drum as the main body, a pyrolysis gas outlet is arranged at the upper left end of the outer spiral drum, a feed inlet is arranged at the upper right end of the outer spiral drum, and a lower end of the right portion is provided with a pyrolysis gas outlet. In the pyrolysis carbon collection box, an electric heating device is installed on the outside of the outer spiral drum, and three support frames are arranged at the lower part of the outer spiral drum to support the entire outer spiral drum; The outer screw and the inner screw are arranged from left to right through the outer spiral drum, wherein the inner screw is located in the center, the inner spiral drum is outside the inner screw, the outer screw is outside the inner spiral drum, and the outer spiral drum is outside the outer screw; pyrolysis carbon The exchange port is arranged on the left side of the inner spiral drum, the carbon circulation port is arranged at the lower end of the right side of the inner spiral drum, and a pyrolysis carbon collection box is arranged at the lower end of the right side of the outer spiral drum; the motor is arranged on the left side of the outer spiral drum to drive the coaxial rotating screw, namely External screw and internal screw.

The biomass raw material enters the outer spiral drum from the feeding port, and is mixed with the circulating pyrolysis carbon. The pyrolysis carbon exchange port falls into the inner spiral drum; during the mixing and stirring process, the biomass undergoes a pyrolysis reaction, and the generated pyrolysis gas is discharged from the pyrolysis gas outlet; the pyrolysis carbon falling into the inner spiral drum is in the inner spiral drum Under the conveying action of the screw, it moves to the right, and after reaching the right side of the inner spiral drum, part of the pyrolysis carbon falls into the outer spiral drum through the carbon circulation port, and the rest of the pyrolysis carbon falls into the carbon collection box.

The double helix is a coaxial rotating screw driven by a speed-regulating motor with two blades in opposite helical directions. There are two grooves on the left and right ends of the outer screw. The pyrolysis carbon exchange port allows the pyrolysis carbon to enter the inner screw from the outer helical drum. The drum, the carbon circulation port allows part of the pyrolysis carbon to enter the outer spiral drum from the inner spiral drum to realize the circulation of the pyrolysis carbon in the double-spiral reactor.

Combining the two heating methods of internal pyrolysis carbon cycle, biomass mixed heat exchange and external electric heating, the change of screw rotation speed is used to affect the characteristics of solid residence time, so that the biomass pyrolysis temperature is 500℃-600℃, and the solid residence time is 1 -30min.

Working principle: The speed regulating motor drives two screws, namely the outer screw 6, and the inner screw 7 rotates at the same time. Both the inner and outer screws are equipped with spiral blades, but the rotation directions are opposite. The biomass raw material is fed into the outer spiral drum and mixed with the circulating pyrolysis carbon. According to the direction shown in the figure, under the stirring action of the blades, the mixture is continuously mixed and moved to the left, and falls off the pyrolysis carbon exchange port on the left side of the inner spiral drum. into the inner rotating drum. During this mixing and stirring process, the biomass undergoes a pyrolysis reaction, and the generated pyrolysis gas is discharged from the pyrolysis gas outlet. The pyrolytic carbon falling into the inner rotating drum moves to the right side of the inner rotating drum under the conveying action of the spiral. The pyrolytic carbon falls into the carbon collection box.

Preferably, the solid temperature in the pyrolysis reactor is controlled at 500-600° C., and the material stays in the pyrolysis reactor for 1-30 minutes, thereby realizing medium-speed pyrolysis of biomass.

The pyrolysis reactor of the present invention does not need to be fed with a fluidized carrier gas during operation, but the biomass material is subjected to a helical mechanical displacement along the inner wall of the high-temperature reactor through the rotary motion of the screw, and can be changed by changing the outer surface of the reactor wall. The heating temperature and the rotation speed of the screw can adjust the heating temperature and heating time of the biomass material, so that the biomass material can achieve selective pyrolysis conversion, such as pyrolysis liquefaction, pyrolysis gasification or pyrolysis carbonization.

Beneficial effect: Compared with the prior art, the present invention has the following advantages:

1. The use of two heating methods, internal coke recycling and external electric heating, enhances heat transfer, making the device have the advantages of high reaction heat intensity per unit volume and large biomass processing capacity;

2. Internal coke recycling provides a solution to the heat source problem of the mobile pyrolysis unit;

3. The spiral structure is used in the pyrolysis reactor to transport the material, which promotes the mixing of the heat carrier and the material, and the rotational speed can be adjusted to adjust the residence time of the solid to change the yield of each pyrolysis product, which is convenient for different types and different particles. Biomass in the diameter range for pyrolysis treatment;

4. Pyrolytic carbon acts as both a heat carrier and a catalytic cracking medium, which maintains an ideal pyrolysis temperature environment, promotes the secondary cracking reaction of pyrolysis steam, and produces a large proportion of lower molecular weight condensable organic heavy tars and permanent fuel gas ( _H2 and CO).

Description of drawings

Fig. 1 is the structural representation of the present invention;

Fig. 2 is the structural representation of the inner screw in Fig. 1;

FIG. 3 is a schematic structural diagram of the outer screw and the inner helical drum in FIG. 1 .

There are: pyrolysis gas outlet 1, electric heating device 2, outer spiral drum 3, inner spiral drum 4, feed port 5, outer screw 6, inner screw 7, motor 8, pyrolysis carbon exchange port 9, support frame 10, charcoal circulation port 11, pyrolysis charcoal collection box 12.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

As shown in FIG. 1 , a double-screw pyrolysis reactor based on the internal circulation of pyrolysis carbon to enhance heat transfer of the present invention takes a horizontal cylindrical outer spiral drum 3 as the main body, and the upper left end of the outer spiral drum 3 is provided with a heat The degassing outlet 1 is provided with a feed port 5 at the upper right end of the outer spiral drum 3, a pyrolysis carbon collection box 12 is arranged at the lower end of the right portion, an electric heating device 2 is installed outside the outer spiral drum 3, Three supporting frames 10 are provided to support the entire outer helical drum 3; in the outer helical drum 3, two coaxial rotating screws with opposite blade helical directions, namely the outer screw 6 and the inner screw 7 are arranged from left to right through the outer helical drum 3, The inner screw 7 is located in the center, the inner screw drum 4 is outside the inner screw 7, the outer screw 6 is outside the inner screw drum 4, and the outer screw drum 3 is outside the outer screw 6; the pyrolysis carbon exchange port 9 is provided in the inner spiral drum On the left side of 4, the carbon circulation port 11 is arranged at the lower end of the right side of the inner spiral drum 4, and a pyrolysis carbon collection box 12 is arranged at the lower end of the right side of the outer spiral drum 3; the motor 8 is arranged on the left side of the outer spiral drum 3 to drive the coaxial rotating screw, namely Outer screw 6 and inner screw 7. The working process of the double-screw pyrolysis reactor based on the internal circulation of pyrolysis carbon to enhance heat transfer is as follows: The biomass raw material is fed into the outer spiral drum 3 from the feed port 5, mixed with the circulating pyrolysis carbon, and is placed in the blade according to the direction shown in the figure. Under the stirring action of , the mixture is continuously mixed and moved to the left, and falls into the inner rotating drum 4 from the pyrolysis carbon exchange port 9 on the left side of the inner spiral drum. During this mixing and stirring process, the biomass undergoes a pyrolysis reaction, and the generated pyrolysis gas is discharged from the pyrolysis gas outlet 1 . The pyrolysis carbon falling into the inner rotating drum moves to the right side of the inner rotating drum 4 under the action of the spiral conveying, and part of the pyrolysis carbon falls to the right side of the inner rotating drum from the pyrolysis carbon recirculation tank 11 and falls into the outer rotating drum , and the rest of the pyrolysis carbon falls into the carbon collection box 12 .

The pyrolysis steps are:

S1. The pyrolyzer reactor is gradually heated to 500°C, and kept at this temperature for 30 minutes. During the heating stage, the motor is also turned on, and the rotational speed of the inner and outer spirals is set;

S2. Feed the biomass material into the outer spiral drum from the feeding port 5, and move to the left side of the reactor under the action of the outer spiral, and pyrolyze at the same time;

S3, the pyrolysis carbon obtained in step S2 falls into the outer rotating drum from the carbon circulation port 11 and is heated to 500-600 ℃ with the biomass material, and is transported to the left side of the pyrolysis reactor again;

S4, the high temperature remaining pyrolysis carbon obtained in step S2 is discharged to the carbon collection box 12 from the right side of the inner rotating drum;

S5. The bio-oil vapor obtained in step S2 is discharged into the corresponding condensing device from the pyrolysis gas outlet.

Case number one:

Raw materials: rice husk, wheat straw

The biomass material is rice husk with a moisture content of 6.7%, a length of about 30mm, and a processing capacity of 50kg/h;

Process:

The rice husks are fed into the outer spiral drum by the feeding port 5, and the rotational speeds of the inner and outer spirals are set to be 2 rev/min and 8 rev/min respectively. Under the conveying action of the spiral, the mixture is continuously mixed and moves to the left, to the left side of the inner drum. From the pyrolysis carbon exchange port 9, it falls into the inner rotating drum. Part of the material falling into the inner rotating drum moves to the right under the conveying action of the screw, part of the material to the right side of the inner drum falls into the outer rotating drum through the carbon circulation port 11, and the rest of the material is discharged from the right side of the inner rotating drum to the carbon collection box 12.

Case 2:

The biomass material is wheat straw with a moisture content of 4.6%, after simple crushing treatment, the length is about 100mm, and the processing capacity is 50kg/h;

Process:

The wheat straw is fed into the outer spiral drum through the feeding port 5, and the rotation speeds of the inner and outer spirals are set at 3 rpm and 10 rpm respectively. From the pyrolysis carbon exchange port 9, it falls into the inner rotating drum. Part of the material falling into the inner rotating drum moves to the right under the conveying action of the screw, part of the material to the right side of the inner drum falls into the outer rotating drum through the carbon circulation port 11, and the rest of the material is discharged from the right side of the inner rotating drum to the carbon collection box 12.

The above is only the preferred embodiment of the present invention, it should be pointed out that: for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can also be made, and these improvements and modifications are also It should be regarded as the protection scope of the present invention.

Claims (4)

1. A double-helix pyrolysis reactor based on pyrolysis carbon internal circulation enhanced heat transfer is characterized in that the double-helix pyrolysis reactor takes a horizontal cylindrical outer spiral roller (3) as a main body, a pyrolysis gas outlet (1) is arranged at the upper end of the left part of the outer spiral roller (3), a feed inlet (5) is arranged at the upper end of the right part of the outer spiral roller (3), a pyrolysis carbon collecting box (12) is arranged at the lower end of the right part of the outer spiral roller, an electric heating device (2) is arranged outside the outer spiral roller (3), and three support frames (10) are arranged at the lower part of the outer spiral roller (3) to support the whole outer spiral roller (3); two coaxial rotating screws with opposite blade spiral directions, namely an outer screw (6) and an inner screw (7), are arranged in the outer spiral roller (3) and penetrate through the outer spiral roller (3) from left to right, wherein the inner screw (7) is positioned at the center, the inner screw (4) is arranged outside the inner screw (7), the outer screw (6) is arranged outside the inner spiral roller (4), and the outer spiral roller (3) is arranged outside the outer screw (6); a pyrolytic carbon exchange port (9) is arranged at the left side of the inner spiral roller (4), a carbon circulation port (11) is arranged at the lower end of the right side of the inner spiral roller (4), and a pyrolytic carbon collection box (12) is arranged at the lower end of the right side of the outer spiral roller (3); the motor (8) is arranged on the left side of the outer spiral roller (3) and drives the coaxial rotating screw rods, namely the outer screw rod (6) and the inner screw rod (7).

2. The double-helix pyrolysis reactor based on pyrolysis carbon internal circulation enhanced heat transfer of claim 1 is characterized in that biomass raw materials enter the outer spiral roller (3) from the feeding hole (5) and are mixed with the circulating pyrolysis carbon, and under the stirring action of the blades, the mixture of the biomass raw materials and the pyrolysis carbon is continuously mixed and moves leftwards, and falls into the inner spiral roller (4) from the pyrolysis carbon exchange port (9) to the left side of the outer spiral roller (3); in the mixing and stirring process, the biomass is subjected to pyrolysis reaction, and the generated pyrolysis gas is discharged from a pyrolysis gas outlet (1); the pyrolytic carbon falling into the inner spiral roller (4) moves rightwards under the spiral conveying action of the inner spiral roller, after reaching the right side of the inner spiral roller (4), part of the pyrolytic carbon falls into the outer spiral roller (3) through the carbon circulation port (11), and the rest pyrolytic carbon falls into the carbon collection box (12).

3. The double-helix pyrolysis reactor based on pyrolysis carbon internal circulation enhanced heat transfer as claimed in claim 1 or 2, characterized in that: the double helix is the coaxial rotation screw rod that two blade screw directions opposite that speed regulating motor drove, and both ends respectively open about outer screw rod (6) have two grooves, and pyrolysis charcoal exchange port (9) allow the pyrolysis charcoal to get into interior spiral cylinder (4) by outer spiral cylinder (3), and charcoal circulation mouth (11) allow partial pyrolysis charcoal to get into outer spiral cylinder (3) by interior spiral cylinder (4), realize the circulation of pyrolysis charcoal in double helix reactor.

4. The double-helix pyrolysis reactor based on pyrolysis carbon internal circulation enhanced heat transfer as claimed in claim 1 or 2, characterized in that the characteristic of influencing the solid retention time by the change of the spiral rotating speed is utilized by combining two heating modes of internal pyrolysis carbon circulation, biomass mixed heat exchange and external electric heating, so that the pyrolysis temperature of the biomass is 500-600 ℃, and the solid retention time is 1-30 min.

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