JP2013234274A - Apparatus and method for drying solid fuel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove water from an aqueous solid fuel efficiently with a small amount of solvent, as compared with a conventional dipping method.SOLUTION: An apparatus 100 for drying a solid fuel includes: a steam generating part 110 for generating steam of a water-soluble solvent (for example, methanol) which has lower boiling point than water; and a contact part 130 for bringing the steam into contact with aqueous solid fuels (for example, peat, lignite, brown coal, and subbituminous coal), to remove water from the aqueous solid fuel. Thus the aqueous solid fuel can be dried efficiently with a small amount of solvent.

Description

  The present invention relates to a solid fuel drying apparatus and a solid fuel drying method for removing water from a hydrated solid fuel containing a large amount of water such as lignite.

  In recent years, a technology for generating gasification gas by gasifying gasification raw materials such as coal, biomass, and tire chips instead of petroleum has been developed. The gasified gas thus generated is used for power generation systems, hydrogen production, synthetic fuel (synthetic petroleum) production, chemical fertilizer (urea) and other chemical products. Among gasification raw materials used as raw materials for gasification gas, coal, in particular, has a recoverable period of about 150 years, which is more than three times the extractable period of oil, and reserves are unevenly distributed compared to oil. Therefore, it is expected as a natural resource that can be supplied stably over a long period of time.

  Coal is classified into peat, lignite, lignite, sub-bituminous coal, bituminous coal, semi-anthracite, anthracite, in order of increasing carbon content. The water content is higher than semi-anthracite and anthracite (hereinafter referred to as anthracite). Therefore, compared with anthracite, water-containing solid fuel has a low calorific value per unit weight, and therefore has low energy efficiency as a fuel for transportation costs.

  Therefore, a technology (immersion method) has been developed that immerses the hydrated solid fuel in a solvent such as methanol and dissolves the water in the hydrated solid fuel in methanol, thereby removing the water from the hydrated solid fuel and drying the hydrated solid fuel. (For example, Patent Document 1).

US Pat. No. 4,014,104

  However, in the technique of Patent Document 1 described above, a large amount of methanol is required for the hydrated solid fuel to be dried. Moreover, in the technique of Patent Document 1, there is a limit to the drying of the hydrous solid fuel.

  Then, in view of such a subject, this invention aims at providing the solid fuel drying apparatus and solid fuel drying method which can remove water from a water-containing solid fuel efficiently with a small amount of solvent.

  In order to solve the above-mentioned problems, the solid fuel drying device of the present invention comprises a steam generation unit that generates a water-soluble solvent vapor having a boiling point lower than that of water, and the water-containing solid fuel by contacting the steam and the water-containing solid fuel. And a contact portion for removing water from the fuel.

  Moreover, the solid-liquid separation part which isolate | separates the liquid mixture of the said water-soluble solvent and water obtained by making the said steam and the said water-containing solid fuel contact in the said contact part from the said water-containing solid fuel from which water was removed. The vapor generation unit may generate the vapor of the water-soluble solvent by fractionating the mixed liquid separated in the solid-liquid separation unit.

  Moreover, the said contact part is good also as making it contact with the said vapor | steam, moving the said water-containing solid fuel.

  In order to solve the above-mentioned problem, the solid fuel drying method of the present invention includes a step of producing a vapor of a water-soluble solvent having a boiling point lower than that of water, and bringing the produced vapor and a hydrous solid fuel into contact with each other. Removing water from the fuel.

  According to the present invention, water can be efficiently removed from a hydrous solid fuel with a small amount of solvent.

It is a figure for demonstrating the structure of a solid fuel drying apparatus. It is a flowchart for demonstrating the flow of a process of the solid fuel drying method. It is a figure for demonstrating the structure of the solid fuel drying apparatus of the modification 1. FIG. It is a figure for demonstrating the structure of the solid fuel drying apparatus of the modification 2. FIG. It is a graph which shows the time change of the moisture content in the water-containing solid fuel of an Example and a comparative example.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

(Solid fuel drying device 100)
FIG. 1 is a diagram for explaining a configuration of a solid fuel drying apparatus 100 according to the present embodiment. As shown in FIG. 1, the solid fuel drying apparatus 100 includes a steam generation unit 110, a steam supply pipe 120, a discharge pipe 122, a contact part 130, a solid-liquid separation part 140, and a return pipe 150. Composed. In FIG. 1, the flow of liquid is indicated by solid arrows, and the flow of gas (vapor) is indicated by broken arrows.

  The steam generation unit 110 generates a water-soluble solvent vapor having a boiling point lower than that of water. In the present embodiment, methanol will be described as an example of a water-soluble solvent having a boiling point lower than that of water, but acetone, ethanol, or the like may be used.

  In the present embodiment, the steam generation unit 110 is configured by, for example, a distillation tower, and includes a main body 112, a reboiler 114, and a reflux unit 116. Note that the steam generator 110 only needs to be able to generate a water-soluble solvent vapor having a boiling point lower than that of water, and is not limited to the configuration shown in FIG. 1, and the main body 112 is packed even if the main body 112 is a multistage distillation column. It may be a distillation column filled with a material. Each function part which comprises the steam generation part 110 is divided and demonstrated at the time of the driving | operation start of the solid fuel drying apparatus 100, and a driving | operation.

  At the start of operation of the solid fuel drying apparatus 100, the main body 112 stores liquid methanol. The reboiler 114 takes out the liquid methanol stored in the main body 112 to the outside, heats it, generates methanol vapor, and returns it to the main body 112. The reflux unit 116 is not operated at the start of operation.

  During operation of the solid fuel drying apparatus 100, the main body 112 stores a mixed liquid (mixed liquid of methanol and water) described later. The reboiler 114 takes out and heats the liquid mixture stored in the main body 112 to generate a mixed vapor of methanol vapor and water vapor, and returns it to the main body 112. The reflux unit 116 condenses the mixed vapor and returns it to the main body 112. With the configuration including the reflux unit 116, the condensed liquid mixture and the mixed vapor can be brought into countercurrent contact in the main body 112, and the water vapor in contact with the condensed liquid mixture is liquefied due to the difference in boiling point between methanol and water. Falls vertically downward to improve the purity of methanol in the mixed steam. Thus, in the steam generation unit 110, the mixed liquid is separated (fractionated) into methanol vapor and water, and the fractionated methanol vapor is sent to the steam supply pipe 120 described later, and the water is discharged from the discharge pipe 122 to the outside. Will be discharged.

  The steam supply pipe 120 is a pipe that connects the upper part of the steam generation part 110 and the main body 132 of the contact part 130, and the methanol steam generated in the steam generation part 110 (hereinafter simply referred to as steam) is supplied as steam. It passes through the tube 120 and is supplied to the main body 132.

  The contact unit 130 removes water from the hydrated solid fuel by bringing the steam and the hydrated solid fuel into contact with each other. More specifically, the contact unit 130 includes a main body 132 and a transport unit 134 provided in the main body 132.

  The main body 132 is formed in a cylindrical shape, and an introduction port 132a and a discharge port 132b are provided at both ends thereof. The transport unit 134 is a screw feeder in which the drive unit 134a rotates the helical screw 134b and feeds the hydrous solid fuel (or solid fuel) in the direction of the rotation axis, and the hydrous solid fuel (from the introduction port 132a) 1 is conveyed to the discharge port 132b. In addition, the hydrated solid fuel introduced from the inlet 132a has a temperature of about room temperature (for example, 25 ° C.).

  In addition, as described above, the steam supply pipe 120 is connected to the main body 132, and the steam is introduced into the main body 132 through the steam supply pipe 120. In addition, the connection position of the steam supply pipe 120 in the main body 132 is better in the vicinity of the inlet 132a than in the outlet 132b.

  As described above, when steam is supplied to the main body 132, the water-containing solid fuel comes into contact with the steam (exposed to the steam) while being transported from the introduction port 132a to the discharge port 132b by the transport unit 134. become.

  Then, water is removed from the hydrous solid fuel for the following reasons (1) and (2). (1) Since steam is higher in temperature than hydrous solid fuel, when it comes into contact with hydrous solid fuel, it is condensed into methanol (liquid). Then, water in the hydrated solid fuel is dissolved in the condensed methanol, whereby water is removed from the hydrated solid fuel (the hydrated solid fuel is dehydrated).

  (2) When methanol is condensed, latent heat is imparted to the hydrous solid fuel. If it does so, the temperature of the water in a hydrous solid fuel will rise, and water will evaporate. Thereby, the water in the hydrated solid fuel is removed.

  In this way, in the contact portion 130, water is removed from the hydrated solid fuel as it is conveyed from the inlet 132a to the outlet 132b (shown by a gray circle to a black circle in FIG. 1). .

  Further, since the contact part 130 includes the transport part 134, the hydrated solid fuel can be moved while contacting the steam, so that the hydrated solid fuel can be dehydrated continuously.

  The solid-liquid separation unit 140 includes a net, a filter, and the like, and a mixed liquid of methanol and water obtained by bringing steam into contact with the hydrated solid fuel in the contact unit 130 is converted into a solid fuel (hydrated water from which water has been removed). Separated from solid fuel).

  Then, the liquid mixture separated in the solid-liquid separation unit 140 is returned to the main body 112 of the steam generation unit 110 through the return pipe 150.

(Solid fuel drying method)
Next, a solid fuel drying method using the solid fuel drying apparatus 100 will be described. FIG. 2 is a flowchart for explaining the processing flow of the solid fuel drying method.

  As shown in FIG. 2, the steam generation unit 110 generates steam (S200), and the contact unit 130 brings the steam generated in the steam generation step S200 into contact with the hydrated solid fuel, so that water is generated from the hydrated solid fuel. (S210), the solid-liquid separation unit 140 separates the solid fuel and the mixed liquid (S220), and returns the mixed liquid separated in the separation step S220 to the main body 112 of the steam generation unit 110 (S230). .

  As described above, according to the solid fuel drying apparatus 100 and the solid fuel drying method using the solid fuel drying apparatus 100 according to the present embodiment, the water-containing solid fuel has a simple configuration in which the steam is brought into contact with the water-containing solid fuel such as lignite. Water can be removed from. That is, the water-containing solid fuel can be dehydrated (dried).

  In addition, since vapor is more diffusive than liquid, methanol (vapor) is more efficiently applied to the surface of water-containing solid fuel than the conventional technology of immersing and drying water-containing solid fuel in liquid methanol. Can be contacted. Therefore, water can be efficiently removed from the hydrated solid fuel with a small amount of solvent. Thereby, the cost required for methanol (water-soluble solvent) can be reduced.

  In the conventional technique of immersing and drying the hydrous solid fuel in methanol, the mixture of water and methanol after distillation is distilled to distill methanol. A condenser was required because it had to condense. Further, in the conventional technique of immersing and drying the hydrous solid fuel in liquid methanol, a storage tank for temporarily storing liquid methanol is required.

  However, since the solid fuel drying apparatus 100 according to the present embodiment fractionates methanol in the steam generating unit 110 and then sends it to the contact unit 130 as it is without condensing, it does not require a cooler or a storage tank. Space saving can be achieved.

(Modification 1)
FIG. 3 is a diagram for explaining the configuration of the solid fuel drying apparatus 300 of the first modification. As shown in FIG. 3, the solid fuel drying apparatus 300 includes a steam generation unit 110, a steam supply pipe 120, a discharge pipe 122, a contact part 330, a solid-liquid separation part 140, and a return pipe 150. Composed. Note that the steam generator 110, the steam supply pipe 120, the discharge pipe 122, the solid-liquid separation section 140, and the return pipe 150 in the solid fuel drying apparatus 100 described above have substantially the same functions, and thus have the same reference numerals. Thus, the redundant description will be omitted, and the contact portion 330 having a different configuration will be described in detail. In FIG. 3, the flow of liquid is indicated by solid arrows, and the flow of gas (vapor) is indicated by broken arrows.

  The contact portion 330 includes a main body 332 formed in a cylindrical shape and a drive unit (not shown) that rotationally drives the main body 332. At both ends of the main body 332, an introduction portion 332a that is rotatably installed with respect to the main body portion 332 and a discharge portion 332b that is rotatably installed with respect to the main body portion 332 are provided. The long axis is installed at a predetermined angle from the horizontal. Then, in a state where the introduction part 332a and the discharge part 332b are fixed, the drive part rotates the main body 332 about the long axis of the main body 332 as a rotation axis.

  Thus, when steam is supplied to the main body 332, the hydrous solid fuel comes into contact with the steam while moving from the introduction part 332a to the discharge part 332b. In other words, the hydrated solid fuel moves while in contact with the steam.

  That is, also in the solid fuel drying apparatus 300, the contact portion 330 can move the hydrated solid fuel while bringing the vapor into contact with each other, so that the hydrated solid fuel can be dehydrated continuously.

(Modification 2)
In the solid fuel drying device 100 described above, the structure in which the transport direction of the hydrated solid fuel and the direction of the flow of the steam are substantially the same in the contact unit 130 has been described. The conveyance direction and the direction of steam flow may be opposed to each other.

  FIG. 4 is a diagram for explaining the configuration of the solid fuel drying apparatus 400 of the second modification. As shown in FIG. 4, the solid fuel drying apparatus 400 includes a steam generation unit 110, a steam supply pipe 420, a discharge pipe 122, a contact part 130, a solid container 440, and a return pipe 450. Is done. In addition, since the steam generation unit 110, the discharge pipe 122, and the contact unit 130 in the solid fuel drying apparatus 100 described above have substantially the same functions, the same reference numerals are given and redundant descriptions are omitted, and the configurations are different. The steam supply pipe 420, the solid container 440, and the return pipe 450 will be described in detail. In FIG. 4, the flow of liquid is indicated by solid arrows, and the flow of gas (vapor) is indicated by broken arrows.

  The steam supply pipe 420 is a pipe that connects the upper part of the steam generation unit 110 and the main body 132 of the contact unit 130, and the steam generated in the steam generation unit 110 passes through the steam supply pipe 120 and is supplied to the main body 132. Is done. In the second modification, the steam supply pipe 420 supplies steam to the downstream side in the transport direction (the discharge port 132b side) of the contact portion 130.

  The solid storage unit 440 stores solid fuel (hydrated solid fuel from which water has been removed) discharged from the discharge port 132 b of the contact unit 130. Here, as will be described later, since the mixed liquid of methanol and water obtained by bringing the vapor into contact with the hydrated solid fuel in the contact portion 130 is discharged from the upstream side in the transport direction in the contact portion 130, The mixed liquid hardly adheres to the solid fuel discharged from 132b.

  The return pipe 450 is a pipe that connects the upstream side in the conveyance direction (inlet port 132a side) and the main body 112 of the steam generation part 110 to the contact part 130, and is obtained by bringing the steam into contact with the hydrated solid fuel in the contact part 130. The obtained mixed liquid of methanol and water is returned to the main body 112.

  That is, in the solid fuel drying apparatus 400, the transport direction of the hydrated solid fuel and the direction of the flow of the steam are opposed to each other in the contact portion 130.

  As described above, also in the solid fuel drying apparatus 400 according to the second modification, water can be removed from the hydrated solid fuel with a simple configuration in which the steam is brought into contact with the hydrated solid fuel such as lignite. That is, the water-containing solid fuel can be dehydrated (dried).

(Example)
As an example, a vapor of methanol at 70 ° C. to 80 ° C. was brought into contact with 120 g of hydrous solid fuel at 0.75 ml / min (liquid conversion). That is, 150 ml (liquid conversion) of methanol vapor was brought into contact with the hydrous solid fuel in 200 minutes. As a comparative example, 120 g of a hydrated solid fuel was immersed in 150 ml of methanol at room temperature (about 25 ° C.). Lignite having a water content of 40% was used as the water-containing solid fuel.

  FIG. 5 is a graph showing the change over time of the moisture content in the hydrous solid fuel of the example and the comparative example. In FIG. 5, an Example is shown by a white circle and a continuous line, and a comparative example is shown by a black square and a broken line. As shown in FIG. 5, in the comparative example, the water content decreased from 40% to 20% in 30 minutes after being immersed, but after 30 minutes, the water content was hardly decreased. Even when immersed for more than 100 minutes, the water content was reduced only to about 18%.

  Dehydration by liquid immersion (comparative example) is performed by diffusing water in a hydrous solid fuel into a liquid solvent. That is, when the concentration of water in the liquid in the hydrated solid fuel is substantially equal to the concentration of water dissolved in the liquid solvent, the diffusion of water from the hydrated solid fuel to the liquid solvent stops. Referring to FIG. 5, in the comparative example, the water of the hydrated solid fuel diffuses (dissolves) in methanol for 30 minutes after being immersed in methanol, but almost no decrease in the moisture content is observed after 30 minutes or more. I can't. In 30 minutes after immersion in methanol, the concentration of water in the liquid in the water-containing solid fuel and the concentration of water dissolved in methanol are substantially equal (equilibrium), and further dehydration proceeds. This is probably because they do not. That is, the critical dehydration rate in the comparative example is 22% (40% -18%).

  On the other hand, in Examples, although the moisture content cannot be decreased rapidly after starting contact with steam, the moisture content can be decreased as the contact time is increased, and 200 minutes. (150 ml), it was found that the water content can be reduced to about 8%. Moreover, the temperature of the hydrous solid fuel was maintained at about 50 ° C to 60 ° C.

  In this example, since the flow rate of methanol vapor was as small as about 0.75 ml / min, it took a longer time than the comparative example to obtain the same dehydration rate as the comparative example. However, if the flow rate of methanol vapor is increased, the same dehydration rate as in the comparative example can be obtained in a shorter time than in the comparative example.

  From the above results, the technique (Example) for bringing the hydrated solid fuel and the steam into contact with each other according to the present embodiment is smaller in amount than the conventional technique (Comparative Example) in which the hydrated solid fuel is immersed in liquid methanol. It was found that the same degree of dehydration can be performed with methanol. More specifically, the comparative example requires 150 ml of methanol at the intersection of the solid line showing the example in FIG. 5 and the broken line showing the comparative example (water content of about 18% when about 110 minutes have passed). In contrast, the example requires only 82.5 ml (0.75 ml x 110 minutes) of methanol.

  Further, in the example, the longer the contact time between the steam and the hydrated solid fuel, the lower the moisture content, that is, the moisture content can be 18% or less (here, 8%). it can. This is because, in the comparative example, the liquid solvent in which the hydrated solid fuel is immersed is not changed, but in the example, fresh (water-free) steam always comes into contact with the hydrated solid fuel. That is, in the example, it is possible to improve the critical dehydration rate to 32% (40% -8%) compared to the comparative example.

  Furthermore, in the Example, since the temperature of the water-containing solid fuel was maintained at about 50 ° C. to 60 ° C., it was found that the latent heat of steam was imparted to the water-containing solid fuel. Thereby, it is considered that the latent heat imparted to the steam also contributes to the reduction of the moisture content.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Is done.

  For example, in the above-described embodiment, the configuration in which the reflux unit 116 is not operated when the operation of the solid fuel drying apparatuses 100, 300, and 400 is started has been described as an example. The reflux unit 116 may be operated at the start of operation.

  Further, in the above-described embodiment, the contact portions 130 and 330 that can move the hydrous solid fuel while contacting the steam have been described. However, the contact portion is not necessarily a hydrous solid if the steam and the hydrous solid fuel can be contacted. There is no need to move the fuel.

  Note that the steps of the solid fuel drying method of the present specification do not necessarily have to be processed in time series in the order described in the flowchart, and may include processing in parallel or by a subroutine.

  INDUSTRIAL APPLICABILITY The present invention can be used in a solid fuel drying apparatus and a solid fuel drying method for removing water from a water-containing solid fuel containing a large amount of water such as lignite.

DESCRIPTION OF SYMBOLS 100, 300, 400 ... Solid fuel drying apparatus 110 ... Steam generation part 130, 330 ... Contact part 140 ... Solid-liquid separation part

Claims (4)

A steam generating section for generating a water-soluble solvent vapor having a lower boiling point than water;
A contact portion for removing water from the hydrated solid fuel by bringing the steam into contact with the hydrated solid fuel;
A solid fuel drying apparatus comprising: A solid-liquid separation unit for separating a mixed liquid of the water-soluble solvent and water obtained by bringing the steam and the hydrous solid fuel into contact with each other in the contact unit from the hydrous solid fuel from which water has been removed; ,
2. The solid fuel drying apparatus according to claim 1, wherein the vapor generation unit fractionates the mixed liquid separated in the solid-liquid separation unit to generate vapor of the water-soluble solvent.   3. The solid fuel drying apparatus according to claim 1, wherein the contact portion contacts the steam while moving the hydrated solid fuel. 4. Producing a water-soluble solvent vapor having a boiling point lower than that of water;
Removing water from the hydrated solid fuel by contacting the generated steam with the hydrated solid fuel;
A solid fuel drying method comprising: