Patent Application
20120168296
This is a continuation of International Application PCT/JP2010/054821 (published as WO 2010/0113679 A1) having an international filing date of Mar. 19, 2010, which claims priority to JP 2009-083887 filed on Mar. 31, 2009. The disclosures of the PCT application and the priority application, in their entity, including the drawings, claims, and the specifications thereof, are incorporated herein by reference.
The present invention relates to the field of producing biocokes using biomass as a raw material, and particularly to a biocoke producing method and a biocoke producing apparatus, which enable industrial mass production of bio-cokes which can be used as substitute fuel for coal cokes.
In view of global worming, reduction of CO2 emission is promoted. Especially, in a steel industry, coal cokes which are fossil fuels are used as fuel and reducing agents at combustion facilities like a Cupola furnace and a power furnace. At combustion facilities like power boiler, fossil fuels such as coal and heavy oil are often used as fuel. However, these fossil fuels are a cause of global warming from a perspective of CO2 emission, and thus the use thereof is becoming more regulated in the view of protecting the global environment. Also from a perspective of fossil fuel drain, there is a need for developing a substitute energy source and putting such substitute energy into practical use.
It has been promoted to use biomass which does not affect on an amount of CO2 emission in the atmosphere instead of fossil fuel. Biomass is an organic matter attributed to photosynthesis such as ligneous matters, grass plants, crops, and kitchen waste. By processing these types of biomass for fuel, it becomes possible to utilize biomass as an energy source or an industrial raw material. This contributes to an environmental preservation. The biomass can be transformed into fuel by drying the biomass to fuel or by pressurizing biomass to a fuel pellet, or by carbonizing and drying to fuel in a solid form or liquid form. However, in the drying method, air ratio in the dried biomass remains large and apparent specific gravity is small, thus making it difficult to transport or store such fuel. This form of fuel is not very efficient for long distance transportation or storage.
A method of processing biomass into a fuel pellet is disclosed in JP 61-27435A. This method includes the steps of adjusting moisture content of comminuted fibrous particles to 16% to 28% by weight, and compressing the material in a die to dry into the fuel pellet. A method of carbonizing the biomass (destructive distillation) is disclosed in JP2003-206490A. According to this method, in oxygen-depleted environment biomass is heated at 200 to 500° C., preferably 250 to 400° C., thus to produce a precursor of charred compact fuel of biomass.
However, according to the method disclosed in JP 61-27435A, biomass is processed into fuel by compacting, processed fuel pallet contains too much moisture and heat value is low, which is not suitable as fuel. Moreover, according to the destructive distillation method disclosed in JP2003-206490A and other references, processed biomass has more value as fuel than unprocessed biomass but still has low apparent specific gravity and has low calorific value in comparison to coal cokes. It also has lower hardness compared to coal cokes, which is not suitable to substitute for coal cokes.
Recently, as an alternative to coal cokes, biocokes are being studied based on JP 4088933 B. The biocoke is produced by pressing and heating biomass raw material for a given period of time and then cooling the biomass raw material in a pressurized state. The pressurizing and heating conditions are set within the pressure and temperature range inducing thermal decomposition of hemicellulose or thermal hardening of cellulose and lignin within the pulverized biomass to induce the pulverized biomass to react at a low temperature while maintaining a structure of cellulose and lignin, thereby obtaining a semi-carbonized solid matter or pre-semi-carbonized solid matter. In this way, reaction mechanism is established and biocoke with high hardness and high density is produced. The pulverized biomass is mainly composed of lignin, cellulose and hemicellulose.
With the reaction mechanism under the above-identified condition, hemicellulose being a fiber component of the pulverized biomass is thermally decomposed and develops adhesion effect, and free water contained in the pulverized biomass induces lignin to react at a low temperature keeping its structure under the above-identified pressurizing and heating condition, which acts with consolidation effect synergistically, thereby producing biocoke with high hardness and high density. The thermal hardening reaction makes progress as reaction activity spots are induced amongst phenolic macromolecules contained in lignin or the like.
Bio-cokes are still in the experiment stage. JP 4088933 B does not disclose a detailed structure of a pressurizing device, a heating device, a cooling device or the like and a control method thereof or how to produce biocokes in a short amount of time and efficiently. Therefore, it is an object of the present invention to provide biocokes producing method and apparatus which can produce biocokes efficiently and in a short amount of time.
In view of the above problems, a first aspect of the present invention is a method of producing biocokes in which pulverized biomass is fed and pressed in a cylindrical reaction container having a bottom part, the pulverized biomass in a substantially-packed state is pressure-formed while being heated in a temperature range and a pressure range to obtain a semi-carbonized solid matter or pre-semi-carbonized solid matter and then cooled to produce biocoke. The method of producing the biocokes may include, but is not limited to, a filling step comprising the substeps of: feeding the pulverized biomass to the reaction container; and then pressing the pulverized biomass in the reaction container by lowering a pressurizing member from above the reaction container at a pressure lower than the pressure range; and a reaction step comprising the substeps of pressurizing the pulverized biomass in the pressure range by increasing a pressure of the pressurizing member to the pressure range; heating the pulverized biomass by means of a heating device to the temperature range and keeping such state for a prescribed period of time to form a shaped matter of the pulverized biomass in the reaction container; and then cooling the shaped matter by switching from the heating device to a cooling device; an ejecting step comprising the substeps of: reducing the pressure of the pressurizing member; and then releasing the bottom part of the reaction container to eject the shaped matter having been cooled.
In the first aspect of the present invention, in the filling step, the pressurizing member is operated first in the first pressure stage to press the pulverized biomass. Next in the reaction step, the pressure of the pressurizing member is increased and in synchronization with this, the heating device is actuated to heat and pressurize the pulverized biomass in an substantially-sealed state in the temperature and pressure range of obtaining the semi-carbonized or pre-semi carbonized solid matter. After keeping the pressurized and heated state for a prescribed period of time, the heating device is switched to the cooling device to cool the pulverized biomass while still maintaining the pressurized state, thereby producing the shaped matter of biocokes. In this manner, the pressurizing member and the heating device and the cooling device are controlled in conjunction. Thus, it is possible to produce biocokes in a short amount of time and efficiently. Further, the biomass of a small grain size is used and thus, bulk density is low. On the other hand, by using unprocessed biomass, it requires a large reaction container. However, in the first aspect of the present invention, the pulverized biomass is pressed at low pressure by the pressurizing member in the filling step and thus, it is possible to input a larger amount of the pulverized biomass. As a result, the reaction container can be downsized.
In the filling step, the pressure of the pressurizing member and an amount of the pulverized biomass filled in the reaction container may be detected in the substep of pressing the pulverized biomass, and the substep of feeding and the substep of pressing may be performed repeatedly until both of the detected pressure of the pressurizing member and the detected amount of the filled pulverized biomass are within a set pressure range and a set amount range of the filling step that are set in advance. By this, it is possible to produce biocokes of the same size without measuring an input amount of the pulverized biomass before inputting to the reaction container, thereby enhancing a product value of the produced biocokes.
In the filling step, the amount of the filled pulverized biomass may be estimated by detecting a position of an upper end of the pulverized biomass fed in the reaction container using a position sensor or by detecting a period during the pressurizing member lowering from an initial position to the upper end of the pulverized biomass. By this, it is possible to detect the amount of the pulverized biomass filled in the reaction container. Particularly, detection can be preferred with precision by using the position sensor, whereas the device can be produced at low cost by using the period of lowering the pressurizing member.
In the filling step, a number of times of lowering the pressurizing member may be counted by a counter in the filling step, and after completing the filling step, when the detected number of times is lower than an expected number of times of lowering the pressurizing member expected in a normal operation state, it may be determined that there is an abnormality in the substep of pressing. In such a case that the number of times of lowering the pressurizing member is lower than the expected number of times expected in the normal operation state, it is assumed that the pressurizing member failed to lower properly due to occurrence of abnormality such as the pressurizing member getting stuck near the inlet of the reaction container. Therefore, it is possible to detect abnormalities during pressurizing the pulverized biomass in a simple manner by counting the number of times of lowering the pressurizing member.
In the above method of producing the biocokes, the heating device and the cooling device may be a cooling/heating medium circulating unit which introduces one of a heating medium and a cooling medium to an outer periphery of the reaction container so as to perform one of heating and cooling of the pulverized biomass, and in the reaction step, the heating medium may be circulated for a set period of time and then the heating medium may be replaced by the cooling medium. In this manner, the cooling/heating medium circulating unit is used as the heating device and the cooling device. Thus, the pulverized biomass is heated or cooled rapidly and switching between heating and cooling of the pulverized biomass can be performed smoothly.
In the ejecting step, the shaped matter may be pushed and ejected from an open bottom of the reaction container by lowering the pressurizing member at a low pressure. By pushing and ejecting the shaped matter of the pulverized biomass by means of the pressurizing member, the biocokes which is shaped in a consolidated manner within the reaction container can be easily ejected.
A second aspect of the present invention is an apparatus of producing biocokes which may include, but is not limited to: a reaction container in which pulverized biomass is fed and pressed and which has a cylindrical shape with a bottom part; a pressurizing member which pressurizes the pulverized biomass in the reaction container; a heating device which heats the pulverized biomass within a temperature range and keeping such state for a prescribed period of time to form a shaped matter of the pulverized biomass in the reaction container, the pulverized biomass in a substantially-packed state being pressure-formed by the pressurizing member while being heated by the heating device within a temperature range and a pressure range in which the pulverized biomass is processed into one of a semi-carbonized solid matter and a pre-semi-carbonized solid matter so as to produce the shaped matter of the pulverized biomass; a cooling device which cools the shaped matter of the pulverized biomass; and a control unit which controls a pressure of the pressurizing member and controls switching between the heating device and the cooling device. The control unit may control a pressure loaded on the pulverized biomass to a first pressure stage which is below the pressure range and a second pressure stage which is within the pressure range, the pulverized biomass being pressed during filling in the reacting container in the first pressure stage and being then pressurized within the pressure range in the second pressure stage, and the heating device may be controlled to operate at the second pressure stage of the pressurizing member for a prescribed period of time and then switched to the cooling device after the prescribed period of time.
The apparatus of producing the biocokes may also include: a pressure detecting device which detects the pressure of the pressurizing member; and a filling-amount detecting device which detects an amount of the pulverized biomass pressed in the reaction container. The control unit may perform a control in the first pressure stage such that feeding of the pulverized biomass and the pressing of the pulverized biomass in the reaction container are performed repeatedly until the pressure detected by the pressure detecting device and the amount of the filled pulverized biomass detected by the filling-amount detecting device are within a set pressure range and a set amount range that are set in advance.
The filling-amount detecting device may be one of a position sensor which detects a position of an upper end the pulverized biomass fed in the reaction container and a device which detects a period during the pressurizing member lowering from an initial position to the upper end of the pulverized biomass so as to estimate the amount of the filled pulverized biomass based on one of the detected position and the detected period. Further, the control unit may include a counter which counts a number of times of lowering the pressurizing member when switching the pressure stages of the pressurizing member, the control unit stopping the pressurizing member when it is determined that there is an abnormality during the pressing in such a case that the detected number of times is lower than an expected number of times of lowering the pressurizing member expected in a normal operation state. Furthermore, the heating device and the cooling device may be a cooling/heating medium circulating unit which introduces one of a heating medium and a cooling medium to an outer periphery of the reaction container so as to perform one of heating and cooling of the pulverized biomass.
In the present invention, in the filling step, the pressurizing member is operated first in the first pressure stage to press the pulverized biomass. Next in the reaction step, the pressure of the pressurizing member is increased and in synchronization with this, the heating device is actuated to heat and pressurize the pulverized biomass in an substantially-sealed state within the temperature and pressure range of obtaining the semi-carbonized or pre-semi carbonized solid matter. After keeping the pressurized and heated state for a prescribed period of time, the heating device is switched to the cooling device to cool the pulverized biomass while still maintaining the pressurized state, thereby producing the shaped matter of biocokes. In this manner, the pressurizing member and the heating device and the cooling device are controlled in conjunction. Thus, it is possible to produce biocokes in a short amount of time and efficiently. Further, the biomass of a small grain size is used and thus, bulk density is low. On the other hand, by using unprocessed biomass, it requires a large reaction container. However, in the first aspect of the present invention, the pulverized biomass is pressed at low pressure by the pressurizing member in the filling step and thus, it is possible to input a larger amount of the pulverized biomass. As a result, the reaction container can be downsized.
In the filling step, the pressure of the pressurizing member and the amount of the pulverized biomass filled in the reaction container is detected in the substep of pressing the pulverized biomass, and the substep of feeding and the substep of pressing are performed repeatedly until both of the detected pressure of the pressurizing member and the detected amount of the filled pulverized biomass are within the set pressure range and the set amount range of the filling step that are set in advance. Thus, it is possible to produce biocokes of the same size without measuring an input amount of the pulverized biomass before inputting to the reaction container, thereby enhancing a product value of the produced biocokes. Further, in the filling step, the amount of the filled pulverized biomass is estimated by detecting a position of an upper end of the pulverized biomass fed in the reaction container using a position sensor or by detecting a period during the pressurizing member lowering from an initial position to the upper end of the pulverized biomass. Thus, it is possible to easily detect the filling amount of the pulverized biomass.
Further, the cooling/heating medium circulating unit is used as the heating device and the cooling device. Thus, the pulverized biomass can be heated or cooled rapidly and switching between heating and cooling of the pulverized biomass can be performed smoothly. In the ejecting step, the shaped matter is pushed and ejected from an open bottom of the reaction container by lowering the pressurizing member at a low pressure. Thus, it is possible to easily eject the biocokes which is shaped in a consolidated manner within the reaction container.
The invention will be described with reference to certain preferred embodiments thereof, wherein:
A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings. It is intended, however, that unless particularly specified, dimensions, materials, shape, its relative positions and the like shall be interpreted as illustrative only and not limitative of the scope of the present invention. In the present invention, biomass used as raw material for producing biocokes is organic matter attributed to photosynthesis. The biomass may be ligneous matters, grass plant, crops, agricultural matters, or the like. For example, biomass may be lumber waste, thinned lumber, pruned branches, plants, agricultural waste and kitchen waste such as coffee grinds and used tea leaves.
In a preferred embodiment of the present invention, pulverized biomass whose moisture content is adjusted to a prescribed percentage of moisture content as needed, is used as a raw material. The pulverized biomass may be biomass of a small grain size such as used tea leaves and coffee grinds without being processed or biomass of a large grain size such as lumber waste which has been pulverized to a prescribed grain size or smaller. In a biocokes-producing apparatus of the preferred embodiment, pulverized biomass in a substantially packed state is pressure-formed while being heated in a temperature range and a pressure range to obtain a semi-carbonized solid matter or pre-semi-carbonized solid matter and after a certain period of time, cooled while keeping a state of pressurization. As a result, biocokes are produced. The above-described temperature and pressure ranges are set within such ranges as to obtain the semi-carbonized solid matter or the pre-semi-carbonized solid matter by inducing the pulverized biomass to react at a low temperature while inducing thermal decomposition of hemicellulose and maintaining a structure of cellulose and lignin within the pulverized biomass. Specifically, in the above-described temperature and pressure ranges, hemicellulose within the pulverized biomass is thermally decomposed and lignin is induced to thermally harden. The pulverized biomass is mainly composed of lignin, cellulose and hemicellulose.
A basic structure of the biocokes-producing apparatus of the preferred embodiment is explained in reference to
The ejecting part 5 has an opening that is the same in diameter as that of the reaction container. Below the ejecting part, an ejecting device is provided to open and close the ejecting part 4. The ejecting device has a bottom cover 9 to cover the ejecting part 5 and a hydraulic ejection mechanism 10 to control releasing of the ejecting part 5. After completing the reaction step within the reaction container 2, the ejecting device drives the hydraulic ejection mechanism 10 to slid the bottom cover 9 and release the ejecting part 5, thereby ejecting the biocokes from the cylinder 2. Over the reaction container 2, a pressurizing device is provided to pressurize the pulverized biomass 11 within the cylinder 2 to a prescribed pressure. The pressurizing device includes a pressurizing piston (a pressurizing member) 6 and a hydraulic pressurization mechanism 8 (see
The hydraulic pressurization mechanism 8, the hydraulic ejection mechanism 10 and the cooling/heating medium circulation mechanism are controlled by a control unit 100. The control unit 100 is constituted of a microcomputer which includes a CPU, a ROM, a RAM and an I/O interface. The control unit 100 further includes a counter 101 and a timer 102. The counter 101 counts a number of times of lowering the pressurizing piston 6 of the hydraulic pressurization mechanism 8. The timer 102 detects a period of time of a prescribed control.
An example of the cooling/heating medium circuit 30 having the cooling/heating medium circulation mechanism is explained in reference to
By using the cooling/heating medium circuit 30, the temperature-regulating device can obtain high thermal efficiency and safety. It is also possible to use a cooling/heating medium circuit of a different structure. In the cooling/heating medium circuit 30, silicon oil is used as the cooling and heating medium. The medium inlet 4a and the medium outlet 4b of the reaction container 2 are connected to the cooling/heating medium circuit shown in the drawing. The cooling/heating medium circuit 30 is configured by combining a cooling medium circuit and a heating-medium circuit. The medium outlet 4b is connected to a medium ejection line 41 and branches into a heating-medium return line 42 and a cooling medium return line 43 at a three-way valve 45 disposed in the medium ejection line 41. The heating-medium return line 42 is connected to a heating-medium tank 31. The heating-medium tank 31 is equipped with a heater 31a and a stirrer 31b to raise a temperature of the heating medium having been cooled. Preferably N2 gas is supplied from a N2 gas cylinder as needed and it is kept in an inert atmosphere inside the tank to ensure the safety. An outlet side of the heating-medium tank 31 is connected to a cooling/heating medium supply line 40 via a three-way valve 46. With the above structure, during heating of the reaction container 2, the three-way valves 45 and 46 are controlled to circulate the heating medium toward the heating-medium tank 31 and thus, the heating-medium circuit is formed by the heating-medium tank 31, the cooling/heating medium supply line 40, the cooling/heating medium path 4 (the reaction container 2), the medium ejection line 41 and the heating-medium return line 42.
The cooling-medium return line 43 is connecting to a cooling/heating medium exchanger 36. The heating/cooling medium exchanger 36 cools the cooling medium by heat exchange with cooling water such as clean water. Preferably, a cooling-medium tank 35 is provided on an upstream side of the cooling/heating medium exchanger 36 in the cooling-medium return line 43. The cooling-medium tank 35 is capable of cooling the cooling medium at least to a boiling temperature or below, preferably to 80° C. or below. The cooling-medium tank 35 is preferably provided with a stirrer 35a. This suppresses a temperature change of the cooling-medium at the outlet of the cooling-medium tank 35, thereby enhancing the cooling performance. With the above structure, during cooling of the reaction container 2, the three-way valves 45 and 46 are controlled to switch from the heating-medium tank side to the cooling-medium tank side to circulate the cooling medium to the heating-medium tank 31 and thus, the cooling-medium circuit is formed by the cooling-medium tank 35, the cooling/heating medium exchanger 36, the cooling/heating medium supply line 40, the cooling/heating medium path 4 (the reaction container 2), the medium ejection line 41 and the cooling-medium return line 43. In this manner, the cooling/heating medium circulation mechanism with the cooling/heating medium circuit 30 is used as the heating device and the cooling device for heating and cooling the pulverized biomass 11 in the reaction container 2. Thus, the pulverized biomass 11 is heated or cooled rapidly and switching between heating and cooling of the pulverized biomass 11 can be performed smoothly.
A process of producing biocokes in relation to the preferred embodiment is explained in reference to
On the other hand, in such a case that the period of pressurization detected by the timer 102 has passed beyond the preset prescribed period when the hydraulic pressure P of the pressurizing cylinder 7 is higher than the prescribed pressure P1, a filling amount of the pulverized biomass 11 in the reaction container 2 is detected so that the pulverized biomass 11 is shaped into a target size. The detection of the filling amount of the pulverized biomass 11 is performed as below. The position sensor 20 detects a position H of an upper end of the pulverized biomass 11 fed in the reaction container 2. Then, it is determined whether or not the detected position H is not less than a preset filling amount H1, i.e. H≧H1.
Alternatively, the filling amount of the pulverized biomass 11 may be estimated by detecting a period during the pressurizing member 6 lowering from the initial position H1 to the upper end H of the pulverized biomass by means of the timer 102. In this case, the period during the pressurization member 6 lowering from the initial position Hi to the upper end H is obtained in advance as a set period T1. In a step S8, it is determined whether or not the detected period T is not greater than the set period T1, T≦T1. In this manner, by using the position sensor or the period T during the pressurizing member 6 lowering from H1 to H, it is possible to detect the filling amount of pulverized biomass 11. Particularly, detection can be preferred with precision by using the position sensor 20, whereas the device can be produced at low cost by using the period of lowering the pressurizing piston 6.
As shown in a stage (ii) of
When it is determined in the step S8 that the filling amount of the pulverized biomass 11 has reached the target filling amount, the process advances to a step S9 to determine whether or not the number of filling the pulverized biomass detected by the counter 101, X0 is less than the prescribed number of filling, Xa. In such a case that X0 is less than the prescribed number of filling, Xa, it is assumed that the pressurizing piston 6 failed to lower properly due to occurrence of abnormality such as the pressurizing piston 6 getting stuck near the inlet of the reaction container 2 and the device is halted in a step S10. In such a case that X0 is not less than the prescribed number of filling, Xa, the process advances to the reaction step. In this manner, the number of filling the pulverized biomass detected by the counter 101, X0 is counted by the counter 101 so as to detect abnormality during pressing the pulverized biomass 11 easily in real time.
In the reaction step, in a step S13, the pressurizing cylinder 7 is driven downward at high pressure to lower the pressurizing piston 6 as shown in
In the ejecting step, in a step S18, the pressurizing cylinder 7 is depressurized as shown in
In the preferred embodiment, first in the filling step, the pressurizing piston 6 is operated in the first pressure stage to press the pulverized biomass 11. Next in the reaction step, the pressure of the pressurizing piston 6 is increased in synchronization with feeding of the heating medium to the cooling/heating medium path 4 to pressurize and heat the pulverized biomass in the reaction container in the temperature and pressure range to obtain the semi-carbonized or pre-semi carbonized solid matter. After keeping the pressurized and heated state for a prescribed period of time, the cooling/heating medium path 4 is switched from the heating medium to the cooling medium to cool the pulverized biomass while still maintaining the pressurized state, thereby producing the shaped matter of biocokes 19. In this manner, the hydraulic pressurization mechanism 8, the hydraulic ejection mechanism 10 and the cooling/heating medium circulation mechanism are controlled in conjunction by the control unit 100. Thus, it is possible to produce biocokes in a short amount of time and efficiently.
With the biocokes-producing apparatus in relation to the preferred embodiment, it is possible to efficiently produce biocokes having high hardness and high density which can be used as an alternative to coal cokes. Further, the biocokes produced according to the preferred embodiment can be used as a heat source, a reducing agent or the like in a Cupola furnace or a blast furnace for a casing manufacture or an iron manufacture, and can be used as a burning fuel such as a power boiler fuel and slaked lime, and also as a material utilizing the high compressive strength of the biocoke.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-083887 | Mar 2009 | JP | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2010/054821 | Mar 2010 | US |
| Child | 13250444 | US |
