Method for manufacturing EFB fibers for fuel

Abstract

The present invention provides a method for producing fuel EFB fibers that can maintain kaolin attached to the EFB fibers, prevent separation of EFB fibers and kaolin in swirling flow gasifiers, flowbed gasifiers, etc., and thus suppress the formation of clinker, slugging, and fouling. [Solution] The method for producing fuel EFB fibers involves spraying a suspension of kaolin mixed with water onto EFB fibers, which are made from pulverized EFB, to adhere the kaolin. This suspension contains at least 1 part by mass of corn starch per 100 parts by mass of water, and is configured to gelatinize the corn starch.

Description

Technical Field

[0001] The present invention relates to a method for producing fuel EFB fibers mainly used for combustion, such as in a swirling flow gasification furnace, from palm empty fruit bunches, that is, EFB (Empty Fruit Bunch).

Background Art

[0002] The fruits of the palm are contained in large numbers in the bunch-shaped palm fruit bunches, and palm oil is obtained by pressing the fruits separated from the palm fruit bunches. The remaining bunch after the fruits are removed, that is, EFB (palm empty fruit bunch), is generated in large quantities at palm oil pressing factories and has been conventionally disposed of as waste. However, in recent years, as described in, for example, Patent Document 1, it has come to be used as a biomass fuel. What is described in Patent Document 1 is a method for producing pellets from EFB fibers obtained by pulverizing EFB, and the produced pellets are burned by boilers or the like.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

[0004] The use of EFB fibers as a raw material for so-called SAF (Sustainable Aviation Fuel) is also being considered. SAF is produced by burning organic waste, for example, to gasify it, removing carbon dioxide to obtain a gas containing carbon monoxide and hydrogen, and then using the so-called Fischer-Tropsch process to bring it to a predetermined temperature and pressure under a predetermined catalyst. In gasification, for example, swirling flow gasifiers and flowbed gasifiers are used, and the use of EFB fibers as fuel supplied to such gasifiers is being considered. When supplying EFB fibers to swirling flow gasifiers, there is no need to form them into pellets; they can be used in their fibrous state.

[0005] Incidentally, EFB fibers, like other herbaceous biomass fuels such as bamboo, have a high ash content consisting of low-melting-point metals such as potassium. When such biomass fuels are burned, the ash melts and solidifies during combustion in swirling flow gasifiers, forming clinker, or vaporizes and adheres to pipes, causing slugging or fouling. Therefore, when burning EFB fibers in swirling flow gasifiers, the EFB fibers are pre-washed to reduce the ash content, or additives that raise the melting point of the ash are added. As such an additive, kaolin is proposed in Patent Document 2. The aluminum oxide contained in kaolin raises the melting point of the ash, which can suppress the formation of clinker, slugging, and fouling. [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] If kaolin is added in the required proportion beforehand when supplying EFB fibers to a swirling flow gasifier, the formation of clinker, slagging, and fouling can be suppressed. However, there are challenges that need to be addressed. Swirling flow gasifiers have a swirling flow inside them. When kaolin-added EFB fibers are supplied to such a swirling flow gasifier, phenomena similar to those in cyclone separators are likely to occur. In a swirling flow gasifier, the strong swirling flow tends to cause the trajectory to be biased according to the aerodynamic properties (particle size, shape, density) of the particles. Therefore, fine kaolin is easily separated from the fibrous EFB and may not be able to maintain sufficient adhesion within the furnace. In that case, the formation of clinker, slagging, and fouling cannot be suppressed.

[0007] The present invention aims to solve the above-mentioned problems, and specifically aims to provide a method for producing fuel EFB fibers that can maintain kaolin properly attached to the EFB fibers, prevent separation of EFB fibers and kaolin in a gasification furnace such as a swirling flow gasification furnace, and thus suppress the formation of clinker, slugging, and fouling. [Means for solving the problem]

[0008] The present invention is configured as a method for producing fuel EFB fibers, wherein a suspension of kaolin mixed with water is sprayed onto EFB fibers, which are made from pulverized EFB, to adhere the kaolin. This suspension is configured to contain 1 part by mass or more of corn starch per 100 parts by mass of water, and to gelatinize the corn starch. [Effects of the Invention]

[0009] In this invention, kaolin is attached to EFB fibers using a suspension of kaolin mixed with water and gelatinized cornstarch. Due to the adhesive properties of the cornstarch, the kaolin is difficult to detach from the EFB fibers even after drying. Therefore, even if the EFB fibers rotate in a swirling flow within a gasification furnace such as a swirling flow gasification furnace, the EFB fibers will burn with the kaolin attached. This suppresses the formation of clinker, slugging, and fouling. [Brief explanation of the drawing]

[0010] [Figure 1] This flowchart shows the method for producing EFB fibers for fuel according to this embodiment. [Figure 2A] These are photographs taken during the experiment. [Figure 2B] These are photographs taken during the experiment. [Figure 2C] These are photographs taken during the experiment. [Figure 2D] These are photographs taken during the experiment. [Modes for carrying out the invention]

[0011] <Preparation of the suspension relating to the concurrence> In the method for producing fuel EFB fibers according to an embodiment of the present invention, a suspension of water, kaolin, and cornstarch is used. In this suspension, the proportions of water, kaolin, and cornstarch are as follows: 10 parts by mass or more, preferably 15 to 25 parts by mass, more preferably 15 to 20 parts by mass, of 100 parts by mass of water, and 1 part by mass or more, preferably 1 to 2 parts by mass, of cornstarch. Increasing the proportion of kaolin relative to water is advantageous because it allows kaolin to adhere to the EFB fibers without increasing the water content, but there is a risk of clogging of the spraying device. Therefore, the above proportions are recommended. Cornstarch is mixed in to obtain adhesiveness in order to prevent kaolin from peeling off the EFB fibers. Increasing the proportion of cornstarch yields higher adhesiveness, but using large amounts of cornstarch increases costs and may cause clogging of the spraying device. Therefore, the above proportions are recommended.

[0012] The suspension will be prepared from these materials, and it is necessary to gelatinize the cornstarch. A preferred preparation method is as follows: Heat water to 60°C or higher, preferably 70°C or higher, for example 80°C, and add kaolin and cornstarch to it and mix. The cornstarch will be reliably gelatinized, or alpha-gelatinized, so the resulting suspension will have the necessary viscosity. Another preparation method is as follows: Heat a small amount of water to 60°C or higher, preferably 70°C or higher, for example 80°C, and mix in cornstarch to gelatinize it. Add the cornstarch gelatinized in this way and kaolin to room temperature water and mix. The resulting suspension will have a water temperature that is substantially at room temperature, but the gelatinized cornstarch will remain in its gelatinized state. In other words, the resulting suspension will have the necessary viscosity.

[0013] <Method for manufacturing EFB fibers for fuel according to this embodiment> A method for producing fuel EFB fibers according to an embodiment of the present invention will now be described. In the method for producing fuel EFB fibers according to this embodiment, a crushing step S1 is first performed as shown in Figure 1. That is, the EFB is crushed to produce EFB fibers. In the crushing step S1, it is preferable to add water to the EFB beforehand to increase its moisture content, and then crush it. This is to ensure that a large amount of water is separated from the EFB during crushing, and a predetermined proportion of ash such as potassium, which causes clinker, slugging, and fouling, is removed along with the water.

[0014] Next, the ash removal process S2 is carried out. The EFB fibers are immersed in a water tank for a predetermined time to increase their moisture content. Then the EFB fibers are compressed. This squeezes out a predetermined proportion of the ash contained in the EFB fibers along with the water. Kaolin is attached to the EFB fibers in a process that will be explained later, and the kaolin raises the melting point of the ash, making it less likely for clinker and other substances to be generated. The ash removal process S2 is not necessarily required, but removing some of the ash in this process can reduce the amount of kaolin needed.

[0015] Drying step S3 is performed. Since the EFB fibers are compressed, i.e., dehydrated, they are dried by supplying hot air while being agitated. Drying step S3 is not an essential step and can be omitted, but drying can increase the lower heating value per unit weight.

[0016] Finally, the kaolin spraying step S4 is performed. The suspension according to this embodiment, as described above, is sprayed onto the EFB fibers using a sprayer. To ensure uniform adhesion of kaolin to the EFB fibers, the suspension may be sprayed while stirring the EFB fibers. Alternatively, the EFB fibers may be dropped in fixed amounts, and the suspension may be sprayed from both sides. Fuel EFB fibers with kaolin attached are obtained. After performing the kaolin spraying step S4, the fuel EFB fibers may be dried as needed. This concludes the explanation of the method for manufacturing fuel EFB fibers according to this embodiment. [Examples]

[0017] In order to confirm that the fuel-use EFB fiber manufactured by the manufacturing method of the fuel-use EFB fiber according to the present embodiment is difficult to peel off kaolin, and thus to confirm that it is a fuel-use EFB fiber capable of appropriately preventing the occurrence of clinker, slugging, etc., various experiments were conducted. [Experiment 1] Purpose: To confirm that kaolin does not adhere even when added to EFB fiber as a powder. Experiment content: Kaolin was added to EFB fiber in a powder state, and then the EFB fiber was vibrated. Most of the kaolin powder dropped from the EFB fiber. Consideration: It was confirmed that kaolin is easily separated just by adding it to EFB fiber as a powder. It was found that it is not suitable for use in a swirling-flow gasification furnace or the like.

Example

[0018] [Experiment 2] Purpose: When spraying kaolin as a suspension onto EFB fiber, to confirm the strength of the adhesion of kaolin depending on the presence or absence of corn starch in the suspension and the magnitude of the corn starch formulation. And to confirm the strength of the adhesion of kaolin depending on the presence or absence of gelatinization of corn starch. Experiment content: Suspension waters A1, A2, A3, B, C, and D were prepared with the following materials and formulations. Suspension water A1: 100 parts by mass of water at 80°C, 20 parts by mass of kaolin, 1 part by mass of corn starch Suspension water A2: 100 parts by mass of water at 80°C, 20 parts by mass of kaolin, 1.5 parts by mass of corn starch Suspension water A3: 100 parts by mass of water at 80°C, 20 parts by mass of kaolin, 2 parts by mass of corn starch Suspension water B: 100 parts by mass of water at 8°C, 20 parts by mass of kaolin, 0.7 parts by mass of corn starch Suspension water C: 100 parts by mass of water at room temperature, 20 parts by mass of kaolin, without corn starch Suspension D: 100 parts by mass of water at room temperature, 20 parts by mass of kaolin, 1 part by mass of corn starch In other words, suspensions A1 to A3 are suspensions according to this embodiment, while suspensions B, C, and D are turbid waters according to comparative examples. EFB fiber A1 was obtained by spraying suspension A1 onto EFB fiber and drying it. Similarly, EFB fibers A2, A3, B, C, and D were sprayed onto EFB fiber and dried to obtain EFB fibers A2, A3, B, C, and D, respectively. A predetermined amount of each of the EFB fibers A1, A2, A3, B, C, and D were placed in a net and dropped onto a sheet five times from a height of 50 cm. The results of the investigation to see if kaolin was observed on the sheet were as follows. EFB fibers A1 to A3 were sprayed with the suspension according to this embodiment, and almost no kaolin deposits were observed on the sheet. For reference, Figure 2A shows a photograph of the sheet when an experiment was conducted with EFB fiber A1. EFB fiber B was prepared by spraying a suspension with a low cornstarch content, and some kaolin fallout was observed on the sheet. For reference, Figure 2B shows a photograph of the sheet from the experiment with EFB fiber B. EFB fiber C was sprayed with a suspension that did not contain cornstarch, and a large amount of kaolin fell onto the sheet. Furthermore, kaolin detached from EFB fiber C even when simply held and lightly shaken by hand. For reference, a photograph of what happens when shaken by hand is shown in Figure 2C. EFB fiber D was prepared by spraying a suspension of cornstarch mixed in an ungelatinized state, resulting in a large amount of kaolin falling onto the sheet. For reference, Figure 2D shows a photograph of the sheet from the experiment with EFB fiber D. Consideration: When the suspension according to this embodiment was prepared and sprayed onto EFB fibers, the kaolin had sufficient adhesion and was difficult to peel off. However, when the amount of cornstarch was small, or when the cornstarch was not gelatinized, the kaolin's adhesion was small and it was easy to peel off. [Examples]

[0019] [Experiment 3] the purpose: When kaolin is sprayed onto EFB fibers as a suspension, the preferred range of kaolin formulations is investigated. Experiment details: Suspensions X1, X2, X3, and X4 were prepared with the following formulations. Suspension x1: 100 parts by mass of water at room temperature, 15 parts by mass of kaolin Suspension x2: 100 parts by mass of water at room temperature, 20 parts by mass of kaolin Suspension x3: 100 parts by mass of water at room temperature, 25 parts by mass of kaolin Suspension x4: 100 parts by mass of water at room temperature, 33 parts by mass of kaolin An experiment was conducted in which suspensions X1, X2, X3, and X4 were placed in their respective designated sprayers and sprayed. Suspensions X1, X2, and X3 were all sprayed properly, but suspension X4 had low fluidity and could not be sprayed. After a short delay, spraying was resumed, and no problems occurred with suspensions X1 and X2, but clogging occurred with suspension X3. Consideration: While it's difficult to generalize because the ease of clogging and spraying varies depending on factors like the nozzle diameter of the sprayer, it was found that spraying is generally possible with a suspension of 25 parts by mass or less of kaolin per 100 parts by mass of water. Furthermore, considering concerns about clogging, a suspension of 20 parts by mass or less of kaolin per 100 parts by mass of water was found to be preferable. In order to efficiently add kaolin, it is preferable to use 15 parts by mass or more per 100 parts by mass of water. [Industrial applicability]

[0020] The fuel EFB fibers according to this embodiment can be used not only by burning them directly in a swirling flow gasifier or the like, but also in other ways. For example, the fuel EFB fibers according to this embodiment can be supplied to a pelletizer to produce fuel pellets. When the fuel EFB fibers are supplied to the pelletizer, they are sucked in by the pelletizer, but even under this suction, the detachment of kaolin from the fuel EFB fibers is prevented. In other words, fuel EFB pellets in which kaolin is uniformly distributed inside can be produced. Therefore, fuel pellets that can appropriately prevent the generation of clinker and the like can be produced. [Explanation of symbols]

[0021] S1 Crushing process S2 Ash removal process S3 Drying process S4 Kaolin spraying process

Claims

1. A suspension of kaolin mixed with water is sprayed onto EFB fibers, which are made from pulverized EFB, to allow the kaolin to adhere. The method for producing EFB fibers for fuel involves providing a suspension containing 1 part by mass or more of corn starch per 100 parts by mass of water, and gelatinizing the corn starch.

2. The method for producing EFB fibers for fuel according to claim 1, wherein the suspension contains 15 to 20 parts by mass of kaolin per 100 parts by mass of water.

3. The method for producing EFB fibers for fuel according to claim 1 or 2, wherein the suspension contains 1 to 2 parts by mass of corn starch per 100 parts by mass of water.

4. A method for producing fuel EFB fibers according to claim 1 or 2, wherein the EFB fibers are dried before spraying the suspension.

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