AU2020291320A1

AU2020291320A1 - Apparatus for producing biochar using combustion heat generator

Info

Publication number: AU2020291320A1
Application number: AU2020291320A
Authority: AU
Inventors: Dong Hoon Shin
Original assignee: Industry Academic Cooperation Foundation of Kookmin University
Current assignee: Industry Academic Cooperation Foundation of Kookmin University
Priority date: 2019-06-12
Filing date: 2020-02-07
Publication date: 2022-02-10
Anticipated expiration: 2040-02-07
Also published as: KR102199489B1; WO2020251132A1; AU2020291320B2; KR20200142395A

Abstract

The present invention relates to a biochar manufacturing device which uses a combustion and heat dissipation plate and enables efficient production of biochar and biogas by using biomass.

Description

[DESCRIPTION]

[Title of Invention]

APPARATUS FOR PRODUCING BIOCHAR USING COMBUSTION HEAT GENERATOR

[Cross-Reference to Related Application]

This application is a National Stage Entry of PCT International Application No.

PCT/KR2020/001775, which was filed on February 07, 2020, and claims priority to Korean Patent

Application No. 10-2019-0069630, filed on June 12, 2019 in the Korean Intellectual Property

Office, the disclosure of which is incorporated herein by reference.

[Field of Invention]

The present invention relates to an apparatus for producing biochar using combustion heat

generator, and more particularly, to an apparatus capable of efficiently producing biochar and

biogas (syngas) using biomass.

[Background of Invention]

In general, when volatile matter generated by applying heat to biomass is converted into

biogas and the biogas is extracted, the remaining carbon mass is called biochar. Carbon dioxide

(C02), which is a climate change material, may be separated and stored as fixed carbon before

combustion reaction, or may be used for other purposes other than combustion, such as a soil

improvement agent, a substitute for active carbon, an organic pollutant adsorbent, and a heavy metal adsorbent. In this way, global warming may be mitigated.

Biochar may be exemplified by charcoal for barbecue or air purification, and may be

produced from all kinds of biomass.

As a typical conventional carbon dioxide (C0 2 ) removal method, there is a technology

(carbon capture (utilization) & storage, CC(U)S) for separating and removing carbon dioxide

generated upon burning carbon. However, separation, purification, compression, transport, and

storage of carbon dioxide (C02 ) consumes a lot of energy and cost. In addition, there are

problems such as air leakage of carbon dioxide and acidification of water and soil due to carbon

dioxide even after storage of carbon dioxide. To date, there is a limit in implementing a carbon

dioxide (C0 2 ) separation and storage technology.

In contrast, when carbon is separated in the form of char before combustion reaction,

carbon dioxide can be easily stored on the surface of the earth in a stable solid form. Since

biochar has high adsorption capacity, biochar can contain water equivalent to three times the

weight thereof. Accordingly, biochar can promote improvement of soil quality, thereby

promoting the growth of biomass. In addition, biochar can adsorb organic substances such as

various hydrocarbons and warming/pollution-causing substances such as heavy metals.

In addition, at a high temperature of 800 °C or higher, since carbon acts as a catalyst for

separating carbon from hydrocarbons and producing hydrogen, a high concentration of hydrogen

can be generated during high-temperature pyrolysis. In this process, carbon is attached to biochar,

and a carbon nanostructure is formed on the surface thereof. Accordingly, the adsorption

capacity of biochar is further increased, and thus a high value product may be produced.

However, in a general technique using biomass, there is a problem in that the flow of raw materials in a reactor is blocked due to the high viscosity of tar generated during pyrolysis.

Therefore, there is a demand for a biomass utilization technology that can overcome these

limitations.

[Disclosure]

[Technical Problem]

Therefore, the present invention has been made in view of the above problems, and it is

one object of the present invention to provide an apparatus for producing biochar using combustion

heat generators, characterized in that the apparatus efficiently produces biochar and biogas using

biomass.

[Technical Solution]

In accordance with one aspect of the present invention, provided is an apparatus for

producing biochar using combustion heat generators, the apparatus including a pyrolysis reactor

having a receiving space therein and provided with an inlet and an outlet; a heater installed inside

the pyrolysis reactor and provided with combustion heat generators for heating biomass input into

the receiving space through the inlet; and an ejector for separating biochar and biogas produced

by heating the biomass in the pyrolysis reactor and discharging the biochar and the biogas through

the outlet.

In this case, the apparatus for producing biochar may further include a gas fuel feeder for

feeding, as fuel for the heater, at least a portion of biogas generated during production of the

biochar.

In addition, in the pyrolysis reactor, the inlet may be formed in an upper portion of the

receiving space, and the outlet may be formed in a lower portion of the receiving space, so that

biomass input into the upper portion of the receiving space through the inlet gradually moves

downward by gravity, and the biomass is heated by the heater and separated into biochar and

biogas.

In addition, the combustion heat generators may be disposed to face each other on both

sides with the receiving space therebetween.

In addition, the combustion heat generator may include a plate-shaped housing having a

combustion space therein; an oxidant injector provided on one side of the housing and forming a

first circulation region by inputting an oxidant to an outer periphery of an inner side of the

combustion space through an oxidant injection nozzle and circulating the oxidant; a gas ejector

provided on the other side of the housing and discharging a portion of gas circulating in the

combustion space; and a fuel feeder installed so that a front end of a fuel injection nozzle is

positioned in a second circulation region formed in a center of the combustion space by circulation

of an oxidant in the first circulation region to inject fuel into the second circulation region.

In addition, a heat exchanger for increasing temperature of an oxidant input through the

oxidant injector and temperature of fuel input through the fuel feeder using heat of gas discharged

through the gas ejector may be provided on one side of the housing.

In addition, the ejector may further include a water cooling jacket installed at an outlet

provided at a lower portion of the pyrolysis reactor and configured to cool discharged biochar by

circulating cooling water therein.

In addition, the apparatus for producing biochar may further include a hot water storage for storing water heated to a predetermined temperature while being used as cooling water in the water cooling jacket so that the heated water is used as hot water.

In addition, the apparatus for producing biochar may further include electric generators

for generating electricity by installing thermoelectric elements between the water cooling jacket

and discharged biochar.

In addition, the apparatus for producing biochar may further include a biogas purifier for

purifying the remaining biogas after being used as fuel for the heater through the gas fuel feeder

and transferring the biogas to an external place or storing the biogas in a separate storage tank.

[Effect of Invention]

An apparatus for producing biochar according to the present invention has a configuration

characterized in that combustion heat generators are disposed to face each other on both sides of

the inside of a pyrolysis reactor. By injecting biomass into a receiving space heated by

combustion heat generator(s) and uniformly dispersing the biomass therein, and heating the

biomass to a temperature of 800 °C or higher, biochar and biogas can be efficiently separated and

produced.

In addition, by using a portion of the produced biogas as a fuel for the combustion heat

generators, the efficiency of the apparatus for producing biochar can be improved.

[Description of Drawings]

FIG. 1 illustrates the internal configuration of an apparatus for producing biochar

according to the present invention.

FIG. 2 illustrates in detail a part of an apparatus for producing biochar according to the

present invention.

FIG. 3 is a perspective view of the combustion heat generator of a heater according to the

present invention.

FIG. 4 is a front sectional view showing the internal configuration of a combustion heat

generator according to the present invention.

FIG. 5 is a front sectional view of a combustion heat generator according to another

embodiment of the present invention.

FIG. 6 is a front view showing an embodiment in which the combustion heat generators

of FIG. 5 are connected in series.

FIG. 7 shows another embodiment in which the combustion heat generator of FIG. 4 is

provided with a plurality of fuel injection nozzles.

FIG. 8 shows another embodiment in which the combustion heat generator of FIG. 4 is

provided with a heat exchanger.

FIGS. 9 and 10 are data showing the results of computational analysis of combustion heat

generators according to the present invention.

[Best Mode]

Hereinafter, the configuration and operation of specific embodiments of the present

invention will be described in detail with reference to the accompanying drawings.

Here, when reference numerals are applied to constituents illustrated in each drawing, it

should be noted that like reference numerals indicate like elements throughout the specification.

according to the present invention.

Referring to FIG. 1, an apparatus 1 for producing biochar according to a preferred

embodiment of the present invention may include a pyrolysis reactor 100, a heater 200, and an

ejector 300.

The configuration of the present invention will be described in detail as follows.

First, the pyrolysis reactor 100 constitutes the main body of the apparatus 1 for producing

biochar. A receiving space (S) may be formed in the pyrolysis reactor 100, and the pyrolysis

reactor 100 may be provided with an inlet 101 and an outlet 103.

Specifically, in the pyrolysis reactor 100, the inlet 101 is formed in the upper portion of

the receiving space (S), and the outlet 103 is formed in the lower portion of the receiving space

(S). Thus, biomass, which is a heating target input through the inlet 101, gradually moves

downward by gravity. The biomass is heated by the heater 200 to be described later, separated

into biochar and biogas(syngas), and then discharged to the outside through the outlet 103.

The heater 200 is installed inside the pyrolysis reactor 100. The heater 200 separates

biomass into biochar and biogas by heating, to about 800 °C or higher, the biomass input through

the inlet 101 and moving downward in the receiving space (S).

The heater 200 separates biomass into biochar and biogas through a pyrolysis process by

heating rather than burning biomass.

In this case, when the biogas meets the high-temperature biochar at the bottom while moving downward in the receiving space (S), the carbon of hydrocarbon is attached to the surface of the biochar, and the biogas is reformed to have a high hydrogen concentration and discharged.

The carbon attached to the biochar may further increase adsorption performance by creating a

carbon nanostructure.

The heater 200 may include combustion heat generators 201 disposed to face each other

with the receiving space (S) therebetween. The present invention is not limited thereto, and

various modifications may be applied as long as the efficiency of the heater 200 can be increased.

For example, a plurality of combustion heat generators 201 may be spaced apart, and the receiving

space (S) of the pyrolysis reactor 100 may be provided between the combustion heat generators

201. Hereinafter, in the present invention, a case in which the combustion heat generators 201

are disposed to face each other with the receiving space (S) therebetween will be described.

Referring to FIG. 2, each of the combustion heat generators 201 may include a housing

210, an oxidant injector 220, a gas ejector 230, and a fuel feeder 240.

First, the housing 210 constitutes the main body of the combustion heat generator 201,

and the housing 210 may be formed in a plate shape in which a combustion space 211 is provided.

In this case, the housing 210 may be made of a stainless or ceramic material that may

withstand high temperatures. When the size of the combustion heat generators 201 increases, the

housing 210 may be manufactured by masonry with fire bricks.

In addition, the housing 210 may be formed in any one of a circular shape, an oval shape,

a rectangular shape, and a polygonal shape. In the present invention, a case in which the housing

210 is formed in a rectangular plate shape will be described. However, the present invention is

not limited thereto, and various modifications may be applied as long as an oxidant and fuel injected into the combustion space 211 may be circulated smoothly.

In this way, when the housing 210 is formed in a plate shape, only two-dimensional flow

is possible in the combustion space 211 inside the housing 210, and three-dimensional flow in the

thickness direction of the housing 210 is impossible.

That is, since the combustion heat generators 201 having a plate shape are formed to have

a large area and a relatively thin thickness, two-dimensional flow is possible. Accordingly,

uniform thermal efficiency of the combustion heat generators 201 may be realized.

Referring to FIG. 3, the oxidant injector 220 is provided on one side of the housing 210

to form a first circulation region (A) by introducing an oxidant into the outer periphery of the inner

side of the combustion space 211 and circulating the oxidant.

Specifically, the oxidant injector 220 may have an oxidant injection nozzle 221 having a

predetermined length so that an oxidant fed through an oxidant feeder (not shown) is smoothly

introduced into a predetermined point of the combustion space 211 in the housing 210.

In this case, the oxidant injection nozzle 221 may be installed at a point where the sides

of the rectangular housing 210 meet each other, i.e., a corner of the housing 210, so as to form the

first circulation region (A) by injecting an oxidant into the outer periphery of the inner side of the

combustion space 211.

As another embodiment, when the housing 210 is formed in a circular shape (not shown),

the oxidant injection nozzle 221 may be installed to be inclined at a predetermined angle in the

tangential direction of the circle. Accordingly, by injecting an oxidant into the outer periphery

of the inner side of the circular combustion space 211, the first circulation region (A) may be

efficiently formed.

The gas ejector 230 may be provided on the other side of the housing 210 and serves to

discharge a portion of gas circulating in the combustion space 211 to the outside.

Specifically, the oxidant injector 220 and the gas ejector 230 may be disposed on one side

of the housing 210 to be spaced apart from each other in parallel.

As another embodiment, as shown in FIG. 4, the oxidant injector 220 and the gas ejector

230 maybe installed with the fuel feeder 240 to be described later therebetween. Inthiscase,the

oxidant injector 220 and the gas ejector 230 may be installed on both sides of the housing 210 and

arranged in a line to face each other.

Referring to FIG. 5, as described above, when the oxidant injector 220 and the gas ejector

230 are installed on both sides of the housing 210 and arranged in a line to face each other, a

plurality of combustion heat generators 201 according to the present invention may be installed in

series to form a lateral heat sink system.

That is, the gas ejector 230 installed on the other side of thefirstly disposed combustion

heat generator 201 may be connected to the oxidant injector 220 installed on one side of the other

adjacent combustion heat generator 201'.

That is, the gas ejector 230 of thefirst combustion heat generator 201 becomes the oxidant

injector 220 of the combustion heat generator 201 connected to the first combustion heat generator

201.

Accordingly, gas discharged through the gas ejector 230 of the first combustion heat

generator 201 may be re-injected through the oxidant injector 220 of the adjacent combustion heat

generator 201. Thus, a long heater may be formed, and the efficiency of the combustion heat

generators 201 may be improved through dispersed injection of fuel.

In this case, in the combustion space 211 inside the housing 210 constituting the

combustion heat generator 201, a guide member 213 for guiding an oxidant may be provided so

that an oxidant injected through the oxidant injector 220 is circulated in one direction of the

combustion space 211.

That is, when a plurality of combustion heat generators 201 is installed in series, it is

necessary to change the flow direction of an oxidant injected into the combustion space 211

through the oxidant injector 220 to a desired direction (e.g., clockwise).

Accordingly, by installing the guide member 213 in the vicinity of the combustion space

211 of the housing 210 in which the oxidant injector 220 is installed, the flow direction of an

oxidant injected into the combustion space 211 through the oxidant injection nozzle 221 may be

changed to a desired direction. Thus, the first circulation region (A) may be smoothly formed.

The fuel feeder 240 serves to inject fuel into a second circulation region (B) formed near

the center of the combustion space 211 by circulation of an oxidant in the first circulation region

(A). The fuel feeder 240 may be installed so that the front end of a fuel injection nozzle 241 is

located in the second circulation region (B).

Specifically, at least one fuel injection nozzle 241 of the fuel feeder 240 may be positioned

between the oxidant injector 220 and the gas ejector 230.

Referring to FIG. 6, as another embodiment, at least one pair of the fuel injection nozzles

241 may be symmetrically installed on the upper and lower sides or left and right sides with respect

to the center of the housing 210 so as to increase the fuel injection efficiency of the fuel feeder

240. Fuel injected through the fuel feeder 240 may receive at least a portion of biogas separated

through the pyrolysis of biomass in the pyrolysis reactor 100.

Referring to FIG. 7, a heat exchanger 250 maybe provided atone side of the housing 210.

The heat exchanger 250 may use the heat of gas discharged through the gas ejector 230 to increase

the temperature of an oxidant input through the oxidant injector 220 and the temperature of fuel

input through the fuel feeder 240. Accordingly, the heat exchanger 250 may improve the thermal

efficiency of the combustion heat generators 201.

FIGS. 8 and 9 show the computational analysis results of the combustion heat generators

201 according to the present invention.

First, the housing 100 was formed to have a size of 5 m in width, 2.5 m in length, and 1

m in thickness so that the combustion heat generators 201 according to the present invention were

used for computational analysis. In this case, the thickness of a metal plate constituting the

housing 210 was 0.1 m, and the fuel injection nozzle 241 was configured to enter 0.7 m from the

wall surface of the housing 210 to the inside.

In addition, gas residence time in the housing 210 was set to 2 seconds, and equivalence

ratio was set to 0.9 to allow 10 % excess air to enter. In addition, methane was used as fuel fed

through the fuel feeder 240.

A computational analysis code used was ANSYS-FLUENT 17.0, a standard k-e model

was used as a turbulence model, a discrete-ordinate model was used as a radiation model, and a

skeletal model of 46 steps was used for chemical reaction.

As shown in FIG. 8, it can be confirmed that, in the combustion heat generators 201

according to the present invention, through the oxidant injector 220, the gas ejector 230, and the

fuel feeder 240 installed in the housing 210, the first circulation region (A) and the second

circulation region (B) are formed inside the combustion space 211.

In particular, as shown in FIG. 9, a fuel-rich region and a reaction activation region in the

first circulation region (A) and the second circulation region (B) of the combustion space 211 may

be identified from CO and OH concentration distributions.

That is, as shown in the computational analysis results, it can be confirmed that, the

combustion heat generators 201 according to the present invention may ensure a uniform

temperature distribution in an entire area except for air and a fuel jet in the combustion space 211.

Referring to FIG. 10, the ejector 300 serves to separate biochar and biogas produced by

heating biomass through the pyrolysis reactor 100 and discharge the biochar and the biogas

through the outlet 103.

Specifically, a screw 301 configured to be rotatable by receiving power from a motor (not

shown) may be provided at the outlet 103 to continuously discharge produced biochar in one

direction.

In addition, the ejector 300 may include a water cooling jacket 310 installed at the outlet

103 provided at the lower portion of the pyrolysis reactor 100. The water coolingjacket310 may

circulate cooling water in an internal space 311 to cool biochar discharged through the outlet 103.

In addition, one side of the ejector 300 may include a hot water storage 320 for storing

water heated to a predetermined temperature while being used as cooling water in the water cooling

jacket310. In this case, the hot water storage 320 maybe maintained at about 60 °C or higher.

In addition, in the ejector 300, thermoelectric elements 331 may be provided between the

water cooling jacket 310 and discharged biochar, and electric generators 330 for generating

electricity may be included. In this case, since the principle of generating electricity using the thermoelectric elements 331 is a known technology, a detailed description thereof will be omitted.

In addition, the apparatus 1 for producing biochar may include a gas fuel feeder (not

shown) to feed, as fuel for the heater 200, at least a portion of biogas generated during production

of biochar.

In this case, the gas fuel feeder may be connected to the fuel feeder 240 (see FIG. 3) of

the heater 300 to feed biogas into the combustion heat generators 201.

In addition, the remaining biogas after being supplied as fuel for the heater 200 through

the gas fuel feeder may be transferred to an external place after a predetermined purification

process through a biogas purifier (not shown), or may be stored in a separate storage tank (not

shown).

In this case, preferably, to use the biogas as a fuel in an external place, acid gas should be

removed using an absorbent, and dust should be removed using a dust collector.

Hereinafter, a biochar production process using the apparatus 1 for producing biochar

according to the present invention having the above-described configuration will be described.

First, through the inlet 101 of the pyrolysis reactor 100, biomass, which is a heating target,

is injected so as to be uniformly dispersed in the receiving space (S) (see FIG. 1).

The biomass input into the pyrolysis reactor 100 through the inlet 101 gradually moves

downward by gravity in the receiving space (S).

The downwardly moving biomass is separated into biochar and biogas while being heated

to a temperature of 800 °C or higher by the combustion heat generators 201 of the heater 200 disposed to face each other on both sides of the receiving space (S).

The produced biochar may be discharged to the outside through the outlet 103 at the

bottom of the pyrolysis reactor 100 in a manner that is transferred in one direction by the screw

301 provided in the ejector 300.

In addition, the water cooling jacket 310 may be provided in the outlet 103 to cool and

discharge the biochar.

In this case, at least a portion of biogas produced with biochar may be used as fuel for the

heater 200, and the remaining biogas may be externally used as fuel through a biogas purifier (not

shown).

As described above, the present invention has been described with reference to certain

preferred embodiments, but the present invention is not limited to the above-described

embodiments, and various changes and modifications may be made without departing from the

spirit of the present invention.

[Description of Symbols]

1: APPARATUS FOR PRODUCING BIOCHAR

100: PYROLYSIS REACTOR

S: RECEIVING SPACE

101: INLET

103: OUTLET

200: HEATER

201: COMBUSTION HEAT GENERATORS

210: HOUSING

211: COMBUSTION SPACE

A: FIRST CIRCULATION REGION B: SECOND CIRCULATION REGION

213: GUIDE MEMBER

220: OXIDANT INJECTOR

221: OXIDANT INJECTION NOZZLE

230: GAS EJECTOR

240: FUEL FEEDER

241: FUEL INJECTION NOZZLE

250: HEAT EXCHANGER

300: EJECTOR

301: SCREW

310: WATER COOLING JACKET

311: SPACE

320: HOT WATER STORAGE

330: ELECTRIC GENERATORS

331: THERMOELECTRIC ELEMENTS

Claims

[CLAIMS]

[Claim 1]

An apparatus for producing biochar, comprising:

a pyrolysis reactor having a receiving space therein and provided with an inlet and an

outlet;

a heater installed inside the pyrolysis reactor and provided with combustion heat generator

for heating biomass input into the receiving space through the inlet; and

an ejector for separating biochar and biogas produced by heating the biomass in the

pyrolysis reactor and discharging the biochar and the biogas through the outlet.
[Claim 2]

The apparatus according to claim 1, further comprising a gas fuel feeder for feeding, as

fuel for the heater, at least a portion of biogas generated during production of the biochar.
[Claim 3]

The apparatus according to claim 1, wherein, in the pyrolysis reactor, the inlet is formed

in an upper portion of the receiving space, and the outlet is formed in a lower portion of the

receiving space, so that biomass input into the upper portion of the receiving space through the

inlet gradually moves downward by gravity, and the biomass is heated by the heater and separated

into biochar and biogas.
[Claim 4]

The apparatus according to claim 1, wherein the combustion heat generators are disposed

to face each other on both sides with the receiving space therebetween.
[Claim 5]

The apparatus according to claim 1, wherein the combustion heat generator comprises a

plate-shaped housing having a combustion space therein;

an oxidant injector provided on one side of the housing and forming a first circulation

region by inputting an oxidant to an outer periphery of an inner side of the combustion space

through an oxidant injection nozzle and circulating the oxidant;

a gas ejector provided on the other side of the housing and discharging a portion of gas

circulating in the combustion space; and

a fuel feeder installed so that a front end of a fuel injection nozzle is positioned in a second

circulation region formed in a center of the combustion space by circulation of an oxidant in the

first circulation region to inject fuel into the second circulation region.
[Claim 6]

The apparatus according to claim 5, wherein a heat exchanger for increasing temperature

of an oxidant input through the oxidant injector and temperature of fuel input through the fuel

feeder using heat of gas discharged through the gas ejector is provided on one side of the housing.
[Claim 7]

The apparatus according to claim 1, wherein the ejector further comprises a water cooling

jacket installed at an outlet provided at a lower portion of the pyrolysis reactor and configured to

cool discharged biochar by circulating cooling water therein.
[Claim 8]

The apparatus according to claim 7, further comprising a hot water storage for storing

water heated to a predetermined temperature while being used as cooling water in the water cooling

jacket so that the heated water is used as hot water.
[Claim 9]

The apparatus according to claim 7, further comprising electric generators for generating

electricity by installing thermoelectric elements between the water cooling jacket and discharged

biochar.
[Claim 10]

The apparatus according to claim 2, further comprising a biogas purifier for purifying the

remaining biogas after being used as fuel for the heater through the gas fuel feeder and transferring

the biogas to an external place or storing the biogas in a separate storage tank.