WO2023276755A1

WO2023276755A1 - Solid fuel production system and solid fuel production method

Info

Publication number: WO2023276755A1
Application number: PCT/JP2022/024517
Authority: WO
Inventors: Masaharu Yamashita; Akihiko Kosugi; Keng Hua CHUAH
Original assignee: Ihi Corporation; Japan International Research Center For Agricultural Sciences; Opteraz Sdn Bhd
Priority date: 2021-07-02
Filing date: 2022-06-20
Publication date: 2023-01-05
Also published as: AU2022304349A1; JP2023533425A; JP7388669B2

Abstract

A solid fuel production system (1) includes a continuous explosion unit (13) configured to explode a lignocellulosic biomass by using water contained in the lignocellulosic biomass. The solid fuel production system (1) includes a dryer (14) configured to dry the lignocellulosic biomass exploded in the continuous explosion unit (13). The solid fuel production system (1) includes a shaping unit (15) configured to shape the lignocellulosic biomass dried in the dryer (14) into a solid fuel.

Description

SOLID FUEL PRODUCTION SYSTEM AND SOLID FUEL PRODUCTION METHOD

The present disclosure relates to a solid fuel production system and a solid fuel production method.

Palm oil is a vegetable oil collected from oil palm fruit and is used in many applications such as food and fuel. Methods of effectively using old palm trunks, palm empty fruit bunches, fronds, mesocarp fiber, and the like have been explored and methods of using them as a solid fuel have been proposed.

Patent Literature 1discloses a solid fuel production method including a juice extraction step in which a sugar solution is extracted from a biomass and a pomace fuel conversion step in which a pomace obtained in the juice extraction step is converted into a solid fuel.

Japanese Patent No. 6403347

In the conventional technique, the solid fuel is produced by mainly using trunks of oil palm as a raw material. Meanwhile, when a solid fuel is produced by using a fibrous biomass as a raw material, sufficient bonding force between fibers cannot be obtained and shaping of a firm solid fuel is sometimes difficult.

Accordingly, an object of the present disclosure is to provide a solid fuel production system and a solid fuel production method that can shape a raw material into a firm solid fuel even if the raw material used contains a fibrous biomass.

A solid fuel production system according to the present disclosure includes a continuous explosion unit configured to explode a lignocellulosic biomass by using water contained in the lignocellulosic biomass. The solid fuel production system includes a dryer configured to dry the lignocellulosic biomass exploded in the continuous explosion unit. The solid fuel production system includes a shaping unit configured to shape the lignocellulosic biomass dried in the dryer into a solid fuel.

The continuous explosion unit may include an extruder.

The lignocellulosic biomass may include a fibrous biomass

The lignocellulosic biomass may include at least one kind selected from the group consisting of empty fruit bunches of oil palm, fronds of oil palm, and mesocarp fiber of oil palm.

The solid fuel production system may further include a grinder configured to grind the lignocellulosic biomass exploded in the continuous explosion unit, and the dryer may dry the lignocellulosic biomass exploded in the continuous explosion unit and grinded in the grinder.

The grinder may include a millstone type grinder.

The grinder may include a wet grinder.

The grinder may remove ash in the lignocellulosic biomass exploded in the continuous explosion unit by using a removal solution containing water.

The solid fuel production system may further include a remover configured to remove ash in the lignocellulosic biomass exploded in the continuous explosion unit by using a removal solution containing water. The grinder may grind the lignocellulosic biomass that has been exploded in the continuous explosion unit and from which the ash has been removed in the remover. The dryer may dry the lignocellulosic biomass exploded in the continuous explosion unit and grinded in the grinder.

The solid fuel production system may further include a remover configured to remove ash in the lignocellulosic biomass by using a removal solution containing water, and the continuous explosion unit may explode the lignocellulosic biomass from which the ash has been removed in the remover.

The solid fuel production system may further include a collector configured to collect palm oil from the lignocellulosic biomass exploded in the continuous explosion unit.

A solid fuel production method according to the present disclosure includes an explosion step of exploding a lignocellulosic biomass with a continuous explosion unit by using water contained in the lignocellulosic biomass. The solid fuel production method includes a drying step of drying the exploded lignocellulosic biomass. The solid fuel production method includes a shaping step of shaping the dried lignocellulosic biomass into a solid fuel.

The present disclosure can provide a solid fuel production system and a solid fuel production method that can shape a raw material into a firm solid fuel even if the raw material used contains a fibrous biomass.

Fig. 1 is a schematic diagram illustrating a solid fuel production system according to one embodiment. Fig. 2 is a schematic diagram illustrating a solid fuel production system according to one embodiment. Fig. 3 is a schematic diagram illustrating a solid fuel production system according to one embodiment. Fig. 4 is a schematic diagram illustrating a solid fuel production system according to one embodiment.

Several exemplary embodiments are described below with reference to the drawings. Note that dimension ratios in the drawings are exaggerated for the sake of description and are sometimes different from actual ratios.

(First Embodiment)
First, a solid fuel production system 1 and a solid fuel production method according to a first embodiment are described by using Fig. 1. In the embodiment, a solid fuel is produced by using lignocellulosic biomass (hereinafter, also referred to as "biomass") as a raw material. As illustrated in Fig. 1, the solid fuel production system 1 includes a remover 11, a dewatering unit 12, a continuous explosion unit 13, a dryer 14, a shaping unit 15, a bioreactor 16, a power generation unit 17, a heater 18, and a steam generator 19. The solid fuel production method according to the embodiment includes a removal step, a dewatering step, an explosion step, a drying step, a shaping step, a methane fermentation step, a power generation step, a heating step, and a steam generation step.

The lignocellulosic biomass is a biomass containing lignocellulose. The lignocellulose may include at least one kind selected from the group consisting of cellulose, hemicellulose, and lignin. The lignocellulosic biomass may include at least one kind selected from the group consisting of wood and grass biomasses, processed products thereof, and waste products thereof. The wood and grass biomasses may include at least one kind of herbaceous biomass and woody biomass. The herbaceous biomass may include at least one kind selected from the group consisting of oil palm, rice, wheat, banana, sugar cane, corn, cassava, sago palm, nipa palm, yam, sorghum, and potato. The woody biomass may include at least one kind selected from the group consisting of cedar, cypress, pine, eucalyptus, and beech.

The lignocellulosic biomass may include a fibrous biomass. The fibrous biomass has long fibers and contains only a small amount of a binder component that is capable of bonding the fibers to one another. Accordingly, the productivity of the solid fuel sometimes decreases unless the binder component or the like is added to the fibrous biomass. However, in the solid fuel production system 1, the biomass is exploded in the continuous explosion unit 13 as described later and this enables shaping of a firm solid fuel.

The lignocellulosic biomass may include at least one kind selected from the group consisting of empty fruit bunches (EFB) of oil palm, oil palm fronds (OPF), and mesocarp fiber (MCF) of oil palm. These biomasses contain fibrous biomasses and are difficult to be shaped into a solid fuel as described above. However, the solid fuel production system 1 is capable of shaping these biomasses into a firm solid fuel and the biomasses can be effectively used as energy resources. Note that, according to the embodiment, the solid fuel production system 1 can shape a biomass into a firm solid fuel even if the biomass contains no fibrous biomass. Accordingly, the biomass may include an oil palm trunk (OPT) and the like.

The removal step is performed in the remover 11. The remover 11 removes ash in the lignocellulosic biomass by using a removal solution containing water. When the solid fuel is combusted in a combustor, the ash may attach to the combustor and become a substance that causes a decrease in combustion efficiency of the combustor. Accordingly, the ash is removed from the biomass before the shaping of the solid fuel to enable production of a solid fuel with a small amount of ash. Moreover, the removal solution contains water and the ash can dissolve into water. Accordingly, the ash can be efficiently removed from the biomass.

Moreover, the biomass contains sap in addition to the ash. Accordingly, in the remover 11, sugar such as glucose, sucrose, and fructose contained in the sap of the biomass can be extracted into the removal solution by means of osmotic pressure. The removal solution containing sugar can be transferred to the bioreactor 16 and used as a raw material for production of biogas. The removal solution may be fresh water such as tap water, groundwater, river water, lake water, or pure water. These waters enable efficient extraction of ash or sugar by means of osmotic pressure.

The remover 11 may include a water tank and remove the ash by immersing the biomass into the removal solution in the water tank. Moreover, the configuration may be such that the remover 11 further includes a conveyance unit such as a belt conveyor and part of the conveyance unit is arranged in the removal solution. Then, the configuration may be such that the biomass is placed on the conveyance unit and the conveyance unit is driven at predetermined speed to automatically continuously perform immersing of the biomass into the removal solution and take-out of the biomass from the removal solution. The remover 11 may also remove the ash by pouring the removal solution onto the biomass.

The longer the time the biomass is in contact with the removal solution is, the greater the amount of ash and sugar extracted from the biomass tends to be. The immersing time of the biomass in the removal solution may be 5 minutes or more, 15 minutes or more, or 30 minutes or more. Although the upper limit of the immersing time is not limited to particular time, the immersing time may be 24 hours or less, 12 hours or less, or 3 hours or less. The temperature of the removal solution may be 5°C or higher and 80°C or lower. The biomass which is a solid content is supplied to the dewatering unit 12 and the removal solution is supplied to the bioreactor 16.

The dewatering step is performed in the dewatering unit 12. In the dewatering unit 12, the biomass which is the solid content and the removal solution which is a liquid content containing the ash and the sugar are separated from each other. The water content rate of the biomass which is the solid content may be 25 mass% or more and 75 mass% or less. The dewatering unit 12 may include at least one type of separator selected from the group consisting of a rotary screen, a centrifugal separator, a screw press, and a filter press. The solid content contains at least one kind selected from the group consisting of cellulose, hemicellulose, and lignin. Moreover, the liquid content contains the ash and the sugar. The biomass which is the solid content is supplied to the continuous explosion unit 13 and the removal solution which is the liquid content is supplied to the bioreactor 16.

The explosion step is performed in the continuous explosion unit 13. The continuous explosion unit 13 explodes the lignocellulosic biomass from which the ash has been removed in the remover 11. The continuous explosion unit 13 explodes the lignocellulosic biomass by using water contained in the lignocellulosic biomass. Specifically, the continuous explosion unit 13 heats and pressurizes the biomass and then rapidly depressurizes the heated and pressurized biomass. This depressurization causes the water contained in the biomass to expand and the biomass is exploded. Fibers of the biomass are thereby defibrated and broke into fine pieces. Accordingly, the biomass becomes soft and has sizes suitable for the shaping of the solid fuel. When the fibrous biomass is supplied to the continuous explosion unit 13, the average length of the fibers of the supplied biomass may be, for example, 5 mm or more and 50 mm or less and the average length of the fibers of the exploded biomass may be about 2 mm or more and 3 mm or less.

Assume the case where the biomass is cut by using a cutter instead of the continuous explosion unit 13. In this case, in order to operate the cutter efficiently, the biomass needs to be dried to such an extent that the water content rate of the biomass falls to or below 5 mass%. However, if the biomass is dried to such an extent that the water content rate falls to the aforementioned level, in order to bond pieces of the biomass together, the biomass needs to be humidified to such an extent that the water content rate of the biomass reaches a predetermined range. However, when the biomass is humidified in steam, for example, only the outer surfaces of aggregations of the fibrous biomass tend to be humidified and the center portions thereof are less likely to be humidified. Accordingly, the biomass is less likely to be uniformly humidified and the pieces of the biomass may be unevenly bonded together. In contrast, since the continuous explosion unit 13 explodes the biomass in the embodiment, the biomass does not have to be dried to such an extent that the water content rate of the biomass falls to or below 5 mass%. Accordingly, the re-humidification of the biomass is unnecessary and it is possible to make the water content rate of the biomass uniform and suppress occurrence of unevenness in binding of pieces of the biomass.

Moreover, exploding the biomass in the continuous explosion unit 13 causes at least one kind selected from the group consisting of cellulose, hemicellulose, and lignin contained in the biomass to be decomposed or chemically change and changes in the properties of a fiber structure can be expected. For example, a bonding property of the pieces of the biomass in the case where the fibrous biomass is exploded in the continuous explosion unit 13 is higher than that in the case where the biomass is cut without use of the continuous explosion unit 13, when the water content rates in the biomasses of the respective cases are the same level. This is assumed to be because sugar such as xylose is produced from hemicellulose by the explosion and such components function as a binder.

The pressure in the pressurization of the biomass in the continuous explosion unit 13 may be 0.7 MPaG or higher. When the pressure is 0.7 MPaG or higher, the water in the biomass is moderately pressurized and heated. Accordingly, the water in the biomass expands after discharging of the biomass and the biomass is moderately exploded. The pressure in the continuous explosion unit 13 is not limited to particular pressure and may be, for example, 10 MPaG or less.

The temperature in the heating of the biomass in the continuous explosion unit 13 may be 100°C or higher. In the case where the aforementioned temperature is 100°C or higher, the water in the biomass that is maintained in a liquid state due to the pressurization vaporizes after the discharging of the biomass and the biomass is moderately broke into pieces. The aforementioned temperature may be 200°C or lower. When the aforementioned temperature is 200°C or lower, excessive explosion of the biomass can be suppressed.

The water content rate of the biomass supplied to the continuous explosion unit 13 may be 25 mass% or more and 75 mass% or less. When the water content rate is within this range, the vaporization of the water in the biomass can cause the biomass to be effectively exploded. Note that the water content rate may be 35 mass% or more and 65 mass% or less.

The continuous explosion unit 13 may include an extruder. The extruder allows continuous explosion of the biomass to be performed in a simple operation. The extruder generally includes a hopper, a cylinder, and a screw provided in the cylinder. The biomass supplied from the hopper is supplied to the screw in the cylinder. The biomass is pressurized and heated in the cylinder by rotation of the screw. When the biomass is discharged from a discharge port of the extruder, the pressure in the biomass is released and the biomass is exploded. The extruder may be a single-screw explosion machine or a multi-screw explosion machine such as a twin-screw explosion machine. The extruder may include a heater. However, since the water in the biomass is heated by the pressurization in some cases, the extruder does not have to include a heater.

The drying step is performed in the dryer 14. The dryer 14 dries the lignocellulosic biomass exploded in the continuous explosion unit 13. The dryer 14 dries the biomass to such an extent that, for example, the water content rate of the biomass becomes about 10 mass% or more and 20 mass% or less. Adjusting the water content rate of the biomass within this range enables easy shaping of the biomass into the solid fuel in the shaping unit 15. The dryer 14 may use steam generated in the steam generator 19 to be described later as a heat source necessary for the drying.

The shaping step is performed in the shaping unit 15. The shaping unit 15 shapes the lignocellulosic biomass dried in the dryer 14 into the solid fuel. Since the solid fuel shaped by the shaping unit 15 can be easily carried, the biomass can be effectively used as fuel. The shaping unit 15 may be a pelletizer and press and shape the biomass into a pellet shape. An L/D ratio (compression ratio) that is a ratio of the length to the diameter of a mold for shaping the biomass into a pellet may be 4 or more and 5.5 or less.

The methane fermentation step is performed in the bioreactor 16. In the bioreactor 16, a biogas containing methane and carbon dioxide is produced from the removal solution containing the sugar by actions of microbes such as methanogens. Moreover, a digestion liquid is produced by the methane fermentation in the bioreactor 16. The digestion liquid can be treated by a publicly known activated sludge treatment method.

The power generation step is performed in the power generation unit 17. The power generation unit 17 generates electric power by using the biogas produced in the bioreactor 16 as fuel. The power generation unit 17 may include a power generator and a gas engine or a gas turbine. The gas engine or the gas turbine operates by using the biogas as fuel to drive the power generator and electric power can be thus obtained. The electric power generated in the power generation unit 17 can be used to drive the solid fuel production system 1. An amount of electric power required to drive the solid fuel production system 1 can be thereby reduced.

The heating step is performed in the heater 18. The heater 18 uses heat generated in the power generation unit 17 to heat water and produces hot water. The hot water produced in the heater 18 can be used as the removal solution to be supplied to the remover 11.

The steam generation step is performed in the steam generator 19. The steam generator 19 generates steam by using the biogas produced in the bioreactor 16 as fuel. The steam generator 19 may include a once-through boiler and generate steam by using the biogas as fuel in the once-through boiler. The steam generated in the steam generator 19 may be supplied to the dryer 14 and used to dry the biomass. An amount of energy supplied from the outside can be thereby reduced.

As described above, the solid fuel production system 1 and the solid fuel production method according to the embodiment can shape a raw material into a firm solid fuel even if the raw material used contains a fibrous biomass.

(Second Embodiment)
Next, a solid fuel production system 1 and a solid fuel production method according to a second embodiment are described by using Fig. 2. As illustrated in Fig. 2, the solid fuel production system 1 of the embodiment greatly differs from that in the first embodiment in the point that it includes a grinder 20 and arrangement of the dewatering unit 12 is changed. The other points are the same as those in the aforementioned embodiment unless otherwise noted and description thereof is thus omitted.

As in the aforementioned embodiment, the remover 11 removes the ash in the lignocellulosic biomass by using the removal solution containing water. In the embodiment, the biomass from which the ash has been removed in the remover 11 is not dewatered in the dewatering unit 12 but is supplied to the continuous explosion unit 13. The continuous explosion unit 13 explodes the lignocellulosic biomass from which the ash has been removed in the remover 11.

As in the aforementioned embodiment, the continuous explosion unit 13 explodes the lignocellulosic biomass by using the water contained in the lignocellulosic biomass. If a biomass such as a fibrous biomass is put into the grinder 20 without being exploded in the continuous explosion unit 13, the fibrous biomass may get entangled and clogged in the grinder 20 due to its shape. In contrast, in the solid fuel production system 1 according to the embodiment, since the biomass is exploded in the continuous explosion unit 13, the biomass is broken into fine pieces. Thus, clogging in the grinder 20 can be suppressed even if a biomass such as a fibrous biomass is used.

The grinder 20 grinds the lignocellulosic biomass exploded in the continuous explosion unit 13. Grinding the biomass with the grinder 20 can destroy vascular bundles and parenchyma of the lignocellulosic biomass and turn the biomass into a slurry form to improve dewatering efficiency of the biomass in the dewatering unit 12. Moreover, grinding with the grinder 20 can promote the extraction of ash and sugar into the removal solution.

The grinder 20 may remove the ash in the lignocellulosic biomass exploded in the continuous explosion unit 13 by using the removal solution containing water. The grinder 20 removes the ash from the biomass before the shaping of the solid fuel to enable production of a solid fuel with only a small amount of ash, like the remover 11. Since the biomass is grinded and broken into fine pieces in the grinder 20, the ash can be efficiency removed. The removal solution may be fresh water such as tap water, groundwater, river water, lake water, or pure water as described earlier. Moreover, in the grinder 20, the sugar contained in the sap of the biomass can be extracted into the removal solution by means of osmotic pressure. The temperature of the removal solution may be 5°C or higher and 80°C or lower. The grinder 20 may use the hot water produced in the heater 18 as the removal solution.

The grinder 20 may include a millstone type grinder. The biomass can be finely grinded by using the millstone type grinder. The millstone type grinder may include an upper grinder and a lower grinder. The millstone type grinder may be configured such that the upper grinder and the lower grinder are arranged to face each other with a clearance provided therebetween and one of the upper grinder and the lower grinder is provided to be rotatable. The upper grinder and the lower grinder may each have an annular shape with an opening in a center portion. The millstone type grinder may be configured such that, when the biomass is supplied from the opening in the center portion of the annular shape, the biomass is discharged from an outer peripheral side of the annular shape as grinded objects while being grinded in the clearance by the rotation of the one of the upper grinder and the lower grinder. The clearance may be 50 μm or more and 1000 μm or less.

The grinder 20 may include a wet grinder or a dry grinder. When the grinder 20 is the wet grinder, the grinder 20 can grind a mixture of the biomass and the removal solution to grind the biomass into fine pieces as well as to remove the ash and collect the sugar by using the removal solution. When the grinder 20 is the wet grinder, the amount of the removal solution added to the biomass may be 0.1 or more and 10 or less in mass ratio. Moreover, the grinder 20 may be a continuous grinder or a batch grinder.

In the dewatering unit 12, the biomass which is the solid content and the removal solution which is the liquid content containing the ash and the sugar are separated from each other as in the aforementioned embodiment. The dewatering unit 12 may include at least one type of separator selected from the group consisting of a rotary screen, a centrifugal separator, a screw press, and a filter press. The biomass which is the solid content is supplied to the dryer 14 and the removal solution which is the liquid content is supplied to the bioreactor 16.

The dryer 14 dries the lignocellulosic biomass exploded in the continuous explosion unit 13 and grinded in the grinder 20. The shaping unit 15 shapes the lignocellulosic biomass dried in the dryer 14 into the solid fuel.

As described above, the solid fuel production system 1 and the solid fuel production method according to the embodiment can shape a raw material into a firm solid fuel even if the raw material used contains a fibrous biomass. Moreover, since the biomass is exploded, clogging in the grinder 20 can be suppressed even if a biomass such as a fibrous biomass is used.

(Third Embodiment)
Next, a solid fuel production system 1 and a solid fuel production method according to a third embodiment are described by using Fig. 3. As illustrated in Fig. 3, the solid fuel production system 1 of the embodiment greatly differs from that in the second embodiment in the point that arrangement of the remover 11 and the continuous explosion unit 13 is different. The other points are the same as those in the second embodiment unless otherwise noted and description thereof is thus omitted.

In the embodiment, first, the continuous explosion unit 13 explodes the lignocellulosic biomass by using the water contained in the lignocellulosic biomass as in the aforementioned embodiment. Then, the biomass exploded in the continuous explosion unit 13 is supplied to the remover 11.

The remover 11 removes the ash in the lignocellulosic biomass exploded in the continuous explosion unit 13 by using the removal solution containing water. Since the remover 11 according to the embodiment is the same as that in the aforementioned embodiment except for the aforementioned point, description thereof is omitted.

The grinder 20 grinds the lignocellulosic biomass that has been exploded in the continuous explosion unit 13 and from which the ash has been removed in the remover 11. The grinder 20 removes the ash in the biomass exploded in the continuous explosion unit 13 by using the removal solution. The dryer 14 dries the lignocellulosic biomass exploded in the continuous explosion unit 13 and grinded in the grinder 20. The shaping unit 15 shapes the lignocellulosic biomass dried in the dryer 14 into the solid fuel.

The solid fuel production system 1 and the solid fuel production method according to the embodiment can shape a raw material into a solid fuel even if the raw material used contains a fibrous biomass. Moreover, since the biomass is exploded, the clogging in the grinder 20 can be suppressed even if a biomass such as a fibrous biomass is used. Furthermore, since the solid fuel production system 1 causes the continuous explosion unit 13 to explode the biomass and then continuously immerses the biomass, it is possible to increase the contact area between the biomass and the removal solution and improve the removal efficiency of the ash.

(Fourth Embodiment)
Next, a solid fuel production system 1 and a solid fuel production method according to a fourth embodiment are described by using Fig. 4. As illustrated in Fig. 4, the solid fuel production system 1 according the embodiment greatly differs from that in the third embodiment in the point that it further includes a collector 21. The other points are the same as those in the third embodiment unless otherwise noted and description thereof is thus omitted.

The continuous explosion unit 13 explodes the lignocellulosic biomass by using the water contained in the lignocellulosic biomass. The biomass exploded in the continuous explosion unit 13 is supplied to the remover 11. The collector 21 collects the palm oil from at least either the removal solution obtained in the remover 11 or the removal solution obtained in the dewatering unit 12

The collector 21 collects the palm oil from the lignocellulosic biomass exploded in the continuous explosion unit 13. The collector 21 may include a centrifugal separator such as a decanter-type three-phase centrifugal separator. The three-phase centrifugal separator can separate an immersion liquid, obtained by the immersing of the biomass, into three phases of a solid content, a light liquid containing the palm oil, and a heavy liquid heavier than the light liquid and containing sugar. The heavy liquid can be supplied to the bioreactor 16 and used as a raw material of the methane fermentation.

In particular, when the biomass contains the mesocarp fiber of oil palm, the explosion destroys the fibers, and separation and free movement of the palm oil from insides of the fibers to surfaces thereof is promoted even if the fibers are the mesocarp fiber after juice extraction. Accordingly, the amount of palm oil collected per unit of raw material can be improved by collecting the separated palm oil. The mesocarp fiber before the explosion and that after the explosion were immersed in water at a mass ratio of mesocarp fiber:water = 1:3. As illustrated in Table 1, it was confirmed that the amount of palm oil collected from the mesocarp fiber after the explosion was greater than the amount of palm oil collected from the mesocarp fiber before the explosion. Note that, in Table 1, TCOD means Total Chemical Oxygen Demand and SCOD means Soluble Chemical Oxygen Demand.

As described above, in the solid fuel production system 1 and the solid fuel production method according to the embodiment, it is possible to shape the biomass into the solid fuel and collect more palm oil from the mesocarp fiber after the juice extraction, which has been conventionally difficult.

The solid fuel production system 1 and the solid fuel production method are described above based on the first to fourth embodiments. Specifically, the solid fuel production system 1 according to the embodiments includes the continuous explosion unit 13 configured to explode the lignocellulosic biomass by using the water contained in the lignocellulosic biomass and the dryer 14 configured to dry the lignocellulosic biomass exploded in the continuous explosion unit 13. The solid fuel production system 1 includes the shaping unit 15 configured to shape the lignocellulosic biomass dried in the dryer 14 into the solid fuel.

Moreover, the solid fuel production method according to the embodiment includes the explosion step of exploding the lignocellulosic biomass with the continuous explosion unit 13 by using the water contained in the lignocellulosic biomass and the drying step of drying the exploded lignocellulosic biomass. The aforementioned method includes the shaping step of shaping the dried lignocellulosic biomass into the solid fuel.

In the solid fuel production system 1 and the solid fuel production method according to the embodiments, the biomass is broken into fine pieces by the explosion and the bonding property between the pieces of biomass also improves due to the reaction caused by the explosion. Accordingly, the biomass does not have to be dried to such an extent that the water content rate falls to or below 5 mass% or less. Thus, a raw material can be shaped into a firm solid fuel even if the raw material used contains a fibrous biomass.

Moreover, since the solid fuel production system 1 crushes the biomass into a chip shape with the maximum dimension of about 2 to 3 mm, the solid fuel production system 1 can use not only the fibrous biomass but also a chip-shaped biomass such as old palm trunks as the raw material of the solid fuel. Thus, the solid fuel production system 1 can be used to shape the fibrous biomass and the chip-shaped biomass into a firm solid fuel without being modified to have dedicated specifications suitable for these kinds of biomass. Specifically, the solid fuel production system 1 can shape into a firm solid fuel, not only the fibrous biomass but also the chip-shaped biomass and even a biomass including the fibrous biomass and the chip-shaped biomass mixed together. This enables efficient production of the solid fuel and can promote effective usage of biological resources that would otherwise be wasted.

The embodiments are described below in further details by using examples and a comparative example. However, the embodiments are not limited to these examples.

(Example 1)
A solid fuel was produced with the same configuration as that in the first embodiment. Specifically, first, fibrous palm empty fruit bunches after crushing and oil extraction were immersed in water. Next, the palm empty fruit bunches were subjected to a dewatering treatment. The palm empty fruit bunches subjected to the dewatering treatment were continuously exploded by using an extruder B55 manufactured by Mori Machinery Corporation. An opening of an outlet gate of the extruder was opened at a rate of 100% and inverter control was set to 50 Hz. Next, the continuously exploded biomass was dried to such an extent that the water content rate was within the range of 12 mass% to 15 mass%. Then, the dried biomass was shaped into pellets.

(Example 2)
A solid fuel was produced with the same configuration as that in the second embodiment. Specifically, first, fibrous palm empty fruit bunches after crushing and oil extraction were immersed in water. Next, the immersed palm empty fruit bunches were taken out and the taken-out palm empty fruit bunches were continuously exploded in the same conditions as those in Example 1. Then, the continuously exploded biomass was mixed with water and the mixture was grinded with a super mass collider that is a millstone type grinder manufactured by Masuko Sangyo Co., Ltd. Next, the grinded biomass was dewatered to such an extent that the water content rate was 50 mass%. An obtained solid content was dried in the same conditions as those in Example 1 and was shaped into pellets.

(Example 3)
A solid fuel was produced with by the same configuration as that in the third embodiment. Specifically, first, fibrous palm empty fruit bunches after crushing and oil extraction were continuously exploded in the same conditions as those in Example 1. Next, the continuously exploded biomass was immersed in water in the same conditions as those in Example 1 and then grinded in the same conditions as those in Example 2. Then, the grinded biomass was dewatered to such an extent that the water content rate thereof was 50 mass%. An obtained solid content was dried in the same conditions as those in Example 1 and was shaped into pellets.

(Comparative Example 1)
Fibrous palm empty fruit bunches after crushing and oil extraction were immersed and dewatered in the same conditions as those in Example 1. Next, the dewatered biomass was dried to such an extent that the water content rate fell to or below 5 mass%, and the dried biomass was cut with a fiber cutter. Then, the cut biomass was humidified to such an extent that the water content rate reached 12 mass% to 15 mass%, and the humidified biomass was shaped into pellets in the same conditions as those in Example 1.

(Evaluation)
(L/D Ratio)
The L/D ratio (ratio of length to diameter) of a mold optimal for the shaping of the pellets was evaluated.

(Bulk Density)
A bulk density in the case where the pellets were shaped in a mold with a L/D ratio of 6 was measured.

(Durability)
The shaped pellets were put in a container, and the container was sealed. The container was rotated for a predetermined period at a predetermined rotation speed such that the pellets collided with one another. Then, the pellets were taken out of the container and the mass of the pellets not pulverized was measured. Next, the rate of the mass of the pellets not pulverized to the mass of the pellets before supplying to the container was calculated and was regarded as durability.

(Yield)
Yield was evaluated from an input amount of the raw material and a production amount of the pellets.

(Power Consumption of Pelletizer)
Power consumption of the pelletizer was evaluated relative to that in Comparative Example 1.

(Drying Energy)
Drying energy used in the drying of the biomass was evaluated relative to that in Comparative Example 1.

(Potassium Content Rate)
The content rate by mass of potassium in the pellets was evaluated.

As illustrated in Table 2, the L/D ratio of the optimal mold decreased and the bulk density was improved in the methods of Examples 1 to 3 in comparison to those in Comparative Example 1. From these results, it was found that the shaping properties of the pellets were improved by the methods of Examples 1 to 3. Moreover, in the methods of Examples 1 to 3, the durability, the yield, and the power consumption of the pelletizer were also improved with the improvements in shaping properties of the pellets. Furthermore, since the biomass was exploded in Examples 1 to 3, there was no need to dry the biomass to such an extent that the water content rate fell to or below 5 mass%. Thus, in the methods of Examples 1 to 3, it was possible to reduce the drying energy by about 20% relative to that in Comparative Example 1. Moreover, in the Examples 2 and 3, the ash was removed not only by immersing the biomass but also by subjecting the biomass to wet grinding. Accordingly, it was possible to reduce the potassium content rate of the pellets to 500 ppm or less by mass. Moreover, in Example 3, since it was possible to reduce the L/D ratio of the pellets from that in Example 2, it was possible to further reduce the power consumption of the pelletizer.

Oil palm fronds and oil palm mesocarp fiber were shaped into pellets in the same method as that in Example 3. It was possible to shape the oil palm fronds and the oil palm mesocarp fiber into pellets like the palm empty fruit bunches.

The entire contents of Malaysian Patent Application No. PI2021003802 (filed July 2, 2021) are incorporated herein by reference.

Although several embodiments are described above, the embodiments may be changed or modified based on the aforementioned disclosed contents. All component elements in the aforementioned embodiments and all features described in the scope of the claims can be individually extracted and combined as long as they do not contradict with one another.

The present disclosure can contribute to, for example, goal 12 "Ensure sustainable consumption and production patterns", goal 13 "Take urgent action to combat climate change and its impacts", goal 15 "Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss" and goal 17 "Strengthen the means of implementation and revitalize the global partnership for sustainable development" of sustainable development goals (SDGs) led by the United Nations.

1 SOLID FUEL PRODUCTION SYSTEM
11 REMOVER
13 CONTINUOUS EXPLOSION UNIT
14 DRYER
15 SHAPING UNIT
20 GRINDER
21 COLLECTOR

Claims

A solid fuel production system comprising:
a continuous explosion unit configured to explode a lignocellulosic biomass by using water contained in the lignocellulosic biomass;
a dryer configured to dry the lignocellulosic biomass exploded in the continuous explosion unit; and
a shaping unit configured to shape the lignocellulosic biomass dried in the dryer into a solid fuel.
The solid fuel production system according to claim 1, wherein the continuous explosion unit includes an extruder.
The solid fuel production system according to claim 1 or 2, wherein the lignocellulosic biomass includes a fibrous biomass.
The solid fuel production system according to any one of claims 1 to 3, wherein the lignocellulosic biomass includes at least one kind selected from the group consisting of empty fruit bunches of oil palm, fronds of oil palm, and mesocarp fiber of oil palm.
The solid fuel production system according to any one of claims 1 to 4, further comprising a grinder configured to grind the lignocellulosic biomass exploded in the continuous explosion unit, wherein
the dryer dries the lignocellulosic biomass exploded in the continuous explosion unit and grinded in the grinder.
The solid fuel production system according to claim 5, wherein the grinder includes a millstone type grinder.
The solid fuel production system according to claim 5 or 6, wherein the grinder includes a wet grinder.
The solid fuel production system according to any one of claims 5 to 7, wherein the grinder removes ash in the lignocellulosic biomass exploded in the continuous explosion unit by using a removal solution containing water.
The solid fuel production system according to any one of claims 5 to 8, further comprising a remover configured to remove ash in the lignocellulosic biomass exploded in the continuous explosion unit by using a removal solution containing water, wherein
the grinder grinds the lignocellulosic biomass that has been exploded in the continuous explosion unit and from which the ash has been removed in the remover, and
the dryer dries the lignocellulosic biomass exploded in the continuous explosion unit and grinded in the grinder.
The solid fuel production system according to any one of claims 1 to 8, further comprising a remover configured to remove ash in the lignocellulosic biomass by using a removal solution containing water, wherein
the continuous explosion unit explodes the lignocellulosic biomass from which the ash has been removed in the remover.
The solid fuel production system according to any one of claims 1 to 10, further comprising a collector configured to collect palm oil from the lignocellulosic biomass exploded in the continuous explosion unit.
A solid fuel production method comprising:
an explosion step of exploding a lignocellulosic biomass with a continuous explosion unit by using water contained in the lignocellulosic biomass;
a drying step of drying the exploded lignocellulosic biomass; and
a shaping step of shaping the dried lignocellulosic biomass into a solid fuel.