Power generation system

Abstract

A power generation system in which the combustion heat of hydrocarbon gas is used to heat the steam for power generation; at the same time, the exhaust heat thereof is used to dry and thy-distill low rank coal. The power generation system includes: a dry distillation step for dry-distilling low rank coal of high moisture content; a cooling step for cooling the fixed carbon obtained in the dry distillation step; a combustion step in which hydrocarbon gas obtained in the dry distillation step is used as the main fuel; and a power generation step in which there are provided a power generator moving a steam turbine by main steam generated in the combustion step and a condenser.

Claims

1. A power generation system comprising: (A) a fixed carbon production device for producing fixed carbon and hydrocarbon gas by dry-distilling and cooling low rank coal; (B) a power generator for combusting the hydrocarbon gas as a main fuel, thereby generating main steam and moving a steam turbine by the main steam and a condenser; and (C) a heat supply unit using exhaust heat from the condenser for heating of inert gas in drying; wherein (D) the fixed carbon production device conducts the dry-distilling and the cooling; and wherein the fixed carbon production device is provided with: a dry distillation furnace for dry-distilling, said dry' distillation furnace being erected in a cooling bath for cooling dry-distilled fixed carbon; a dry distillation unit which is partitioned into a rectangular or a polygonal shape in a vertical direction on a horizontal cross-section in the dry distillation furnace by a separating wall from an upper portion to a lower portion; a plurality of dry distillation mini-furnaces which are each partitioned into a rectangular or a polygonal shape in the vertical direction on the horizontal cross-section in the dry distillation unit by a partition plate from an upper portion to a lower portion: a pipe heating means for heating which is arranged on the separating wall of the dry distillation unit and the partition of each of the dry distillation mini-furnace; and a collection path for collecting fixed carbon produced in the cooling bath by feeding raw material coal from the upper portion and performing dry distillation in each of the dry distillation mini-furnaces by the pipe beating means.

2. The power generation system according to claim 1, further comprising: a dryer for drying the low rank coal prior to the dry-distilling.

3. The power generation system according to claim 2, wherein a drying temperature in the dryer is from 30C to 50 C.

4. The power generation system according to claim 1, wherein a moisture content of the low rank coal in the dry distillation furnace is 20 mass % or less in the drying.

5. The power generation system according to claim 2, wherein a grain size of the low rank coal in the dryer is from 0.1 m to 5 mm.

6. The power generation system according to claim 1, further comprising: a heat supply unit supplying exhaust heat generated in the combusting to the dry-distilling by utilizing steam, combustion exhaust gas, or a heat medium heated in the combusting.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a schematic diagram illustrating a power generation system according to an embodiment.

(2) FIG. 2 is a schematic diagram illustrating a fixed carbon production device according to an embodiment.

(3) FIG. 3 is a schematic diagram illustrating a simulated moving bed indirect heating dry distillation furnace.

(4) FIG. 4 is a graph illustrating analysis results of dry-distilled coal according to dry distillation temperatures.

(5) FIG. 5 is a graph illustrating thermogravimetric analysis results of dry-distilled coal according to dry distillation temperatures.

(6) FIG. 6 is a graph illustrating temperature change in brown coal in a dry distillation furnace.

(7) FIG. 7 is a graph illustrating changes in various combustion-related components of the fixed carbon according to the brown coal dry distillation processing temperatures.

(8) FIG. 8 is a graph illustrating the moisture content in terms of temperature and time in the case of low temperature drying.

(9) FIG. 9 is a diagram illustrating the heat balance and material balance according to an embodiment.

(10) FIG. 10 is a diagram illustrating a dry distillation unit 56 and a dry distillation mini-furnace 57 as described herein. Although one of the dry distillation mini-furnace 57 in the center part of the dry distillation unit 56 is shown as an example, 3 3 rows of dry distillation mini furnaces 57 are provide in the dry distillation unit 56 as described herein. In the blow-up at right, the arrangement of the pipe heating means 58 between the adjacent dry distillation mini-furnaces 57 is shown.

(11) FIG. 11 is a diagram providing an enlarged view of one of the dry distillation mini-furnaces 57 surrounded by the pipe heating means 58 between the adjacent dry distillation mini-furnaces 57. For ease of visualization, the center line is added along with an exemplification of the size for reference.

DESCRIPTION OF EMBODIMENTS

(12) In the following, the mode for carrying out the present invention will be described with reference to the drawings.

(13) (Embodiments)

(14) FIG. 1 is a schematic diagram illustrating a power generation system according to an embodiment.

(15) In the drawing, 1 denotes a power generation system; 2 denotes mining/coal-conveying equipment for mining and conveying low rank coal; 3 denotes a dryer for the drying step which dries the low rank coal such as brown coal which is an aggregate coal of a grain size of 1 m to 5 mm and which has a moisture content of about 60 mass % to a moisture content of 20 mass % at about 30 C. to 50 C. in an N.sub.2 gas atmosphere which has been warmed by an inert gas preheater 30 described below, the coal being conveyed from the mining/coal-conveying equipment 2; 4 denotes a dryer heat exchange unit warming the dryer by using the hot water of 60 C. to 90 C. connected to a condenser 33 described below; 5 denotes a dust collector performing dust collection on the exhaust air; 6 denotes a preprocessing device for warming the dried coal obtained by the dryer 3 to 200 C. to 350 C. as a pre-dry-distillation processing; 7 denotes a preprocessing device heat exchange unit which is supplied with reheated steam at 500 C. to 600 C. obtained at the fluidized bed combustor 13 described below by a reheated steam preprocessing supply unit 45 described below and performing heating to 200 C. to 350 C.; 8 denotes a dried coal bunker for feeding into the dry distillation furnace the dried coal warmed through preprocessing by the preprocessing device 6; 9 denotes a dry distillation furnace for vaporizing and separating the volatile content, tar component, etc., from the dried coal conveyed from the dried coal bunker 8 to dry-distill the coal into fixed carbon and hydrocarbon gas; 10 denotes a dry distillation furnace heat exchange unit supplied with reheated steam at 500 C. to 600 C. heated at the fluidized bed combustor 13 described below by a reheated steam dry distillation furnace supply unit 44 described below and performing heating to 350 C. to 500 C.; 11 denotes a cooling bath for cooling and extracting the fixed carbon obtained at the dry distillation furnace 9; 12 denotes a cooling bath heat exchange unit performing cooling to a temperature not higher than room temperature for the cooling of the cooling bath 8 from a water supply unit 38 described below; 13 denotes a fluidized bed combustor supplied with the hydrocarbon gas produced through dry distillation at the dry distillation furnace 9 as main fuel and generating heat for the main steam for a steam turbine 32 described below; 14 denotes a combustor main steam heat exchange unit generating the main steam for the steam turbine 32 described below by the heat of the fluidized bed combustor 13; 15 denotes a reheated steam heat exchange unit heating again the steam after having rotated the steam turbine 32 described below by the heat of the fluidized bed combustor 13 to create reheated steam; 16 denotes a cyclone separating solid component from the exhaust gas of the fluidized bed combustor 9 by centrifugal force; 17 denotes an ash processing device processing the ash separated by the cyclone 16; 18 denotes a combustion air preheater for performing heat exchange in order to utilize the exhaust gas supplied through piping from the cyclone 16 for the warming of O.sub.2 obtained from an O.sub.2 separator 25 described below; 19 denotes a combustion air preheater heat exchange unit of the combustion air preheater 18; and 20 denotes a CO.sub.2 separation device for separating CO.sub.2 from the exhaust gas heat-recycled by the combustion air preheater 18, the removal of dust, etc., from the exhaust gas after the separation of CO.sub.2 by the CO.sub.2 separation device 20 being performed by the dust collector 5. 21 denotes a chimney for discharging exhaust gas from which dust, etc., has been removed by the dust collector 5; 22 denotes a CO.sub.2 supply unit for supplying the CO.sub.2 separated by the CO.sub.2 separation device 20 to the cooling bath 11 and a pre-heated O.sub.2 supply unit 27 described below; 23 denotes a CCS for recycling and utilizing the CO.sub.2 having passed the cooling bath 11; 24 denotes a forced draft fan for sending air from atmosphere to an O.sub.2 separator described below; 25 denotes an O.sub.2 separator separating the O.sub.2 gas and the N.sub.2 gas from the atmospheric air forced in by the forced draft fan 24 and sending these gases to the combustion air preheater 18; 26 denotes an O.sub.2 supply unit for supplying the O.sub.2 separated by the O.sub.2 separator 25 to the combustion air preheater 18; 27 denotes a pre-heated O.sub.2 supply unit mixing the O.sub.2 warmed by the combustion air preheater 18 with the CO.sub.2 from the CO.sub.2 supply unit 22 and supplying the mixture to the fluidized bed combustor; the O.sub.2 gas obtained from the O.sub.2 separator 25 passes through the O.sub.2 supply unit 26, and is pre-heated by the combustion air preheater 18 to be used as the fuel additive of the fluidized bed combustor 13. Further, the N.sub.2 gas simultaneously obtained is heated by an inert gas preheater 30 described below and is used for the drying of low rank coal. 28 denotes an N.sub.2 gas supply unit supplying the N.sub.2 gas separated from the atmosphere by the O.sub.2 separator 25 to the inert gas preheater 30 described below; 29 denotes a dry air forced draft fan for forcing the inert gas the main component of which is the N.sub.2 gas of the N.sub.2 gas supply unit 28 into an inert gas preheater 30 described below; and 30 denotes an inert gas preheater for pre-heating the inert gas; the inert gas preheater 30 uses the exhaust heat after the heat exchange at the preprocessing device heat exchange unit 7 or the dry distillation furnace heat exchange unit 4. 31 denotes a pre-heated N.sub.2 supply unit supplying the N.sub.2 warmed by the inert gas preheater 30 to the dryer heat exchange unit 4; 32 denotes a steam turbine rotating the power generator with the main steam of the fluidized bed combustor 13; 33 denotes a condenser; 34 denotes a power generator; 35 denotes a cooling tower; 36 denotes a condenser exhaust heat supply unit supplying the exhaust heat of the condenser to the dryer heat exchange unit 4 of the dryer 3; 37 denotes a steam drive type water supply pump; 38 denotes a water supply unit sending the water of the condenser to the cooling bath heat exchange unit 12 of the cooling bath 11 and to a water supply heater 39 described below; 39 denotes a water supply heater for pre-heating the water from the preprocessing device heat exchange unit 7, the dry distillation furnace heat exchange unit 10, the cooling bath heat exchange unit 12, the inert gas preheater 30, and the water supply unit 38 with the steam (extracted steam) from the combustor main steam heat exchange unit 14 and the turbine; 40 denotes a heated water supply unit for supplying heated water from the water supply heater 39 to the combustor main steam heat exchange unit 14; 41 denotes a main steam supply unit for supplying main steam from the combustor main steam heat exchange unit 14 to the turbine; 42 denotes a reheated steam supply unit for supplying the steam having rotated the turbine to the reheated steam heat exchange unit for reheating; 43 denotes a reheated steam return unit returning a part of the reheated steam to the turbine again; 44 denotes a reheated steam dry distillation furnace supply unit for supplying reheated steam to the dry distillation furnace heat exchange unit 10; and 45 denotes a reheated steam preprocessing device supply unit for supplying reheated steam to the preprocessing device heat exchange unit 7. 55 denotes fixed carbon such as char produced.

(16) More specifically, in the present embodiment, the heated water supplied from the heated water supply unit 40 is converted to main steam at the combustor main steam heat exchange unit 14 of the fluidized bed combustor 13. This main steam is supplied to the steam turbine 32 by using the main steam supply unit 41. The steam having rotated the steam turbine 32 is supplied to the reheated steam heat exchange unit 15 by using the reheated steam supply unit 42, and is reheated at the reheated steam heat exchange unit 15 to be turned into reheated steam. A part of this reheated steam is supplied to the steam turbine 32 again by using the reheated steam return unit 43. The reheated steam is supplied to the dry distillation furnace heat exchange unit 10 and the preprocessing device heat exchange unit 7 mainly by the reheated steam dry distillation furnace supply unit 44 and the reheated steam preprocessing device supply unit 45. Further, the reheated steam used in the dry distillation furnace heat exchange unit 10 and the preprocessing device heat exchange unit 7 is supplied to the water supply heater 39 after being partly used by the inert gas preheater 30, or as it is. A part of cold water of the water supply unit 38 is used to cool the fixed carbon at the cooling bath heat exchange unit 12 and is warmed before being supplied to the water supply heating portion 39. In this way, exhaust heat is utilized between the heat media such as water and steam, so that it is possible to reduce the burden on the fluidized bed combustor 13, the cooling tower 35, and the water supply heater 39, so that the system is excellent in resource-saving efficiency.

(17) Further, as the fuel of the combustor, it is possible to use a part of the fixed carbon 55. In this case, when the fixed carbon 55 is fed into the fluidized bed combustor 13 as the requisite input heat for the dryer 3 and the dry distillation furnace 9, the requisite energy for generating the fixed carbon itself is lost; however, it is also possible to utilize it as a means for securing the heat source for the dryer 3 and the dry distillation furnace 9; thus, the system is excellent in fuel selectivity.

(18) The power generation system, arranged as described above will be described as follows in terms of each unit operation.

(19) (1) The low rank coal is coarsely crushed in advance, e.g., in a ball mill and separated and transferred in an air current, and then supplied to the dryer 3 of the power generation system.

(20) (2) In the dryer 3, the moisture content of the low rank coal the grain size of which is adjusted to 0.1 m to 5 mm is reduced to 20 mass % or less, so that the drying is performed with a drying gas the relative humidity of which is 0% to 70% and at a temperature in the dryer ranging from 30 C. to 50 C. As the drying gas, there is utilized the exhaust heat from the condenser 33 and the exhaust heat recycled from the steam turbine, the combustor bed material, and the fixed carbon.

(21) (3) As the dry distillation furnace 9, it is desirable to adopt the moving bed system indirectly heated to 350 C. to 500 C. This makes it possible to obtain fixed carbon while retaining the tar component, making it possible to prevent problems such as caulking of the tar component. Further, it is possible to extract the hydrocarbon gas of the light oil component, thus making it easier to handle the combustor.

(22) (4) The fluidized bed combustor 13 uses a fuel additive obtained by diluting the oxygen separated by the O.sub.2 separator 25 for separating oxygen from the atmosphere by carbon dioxide gas obtained as by-product or separated from the CO.sub.2 separation device 20.

(23) (5) The CO.sub.2 separation device 20 employs a solid reform catalyst such as iron or an alkaline component. More specifically, it is possible to utilize a fixed bed, etc., which employs a perovskite carrying alkaline earth catalyst. This makes it possible to decompose a heavy component such as a tar component into a light component.

(24) (6) Since there is provided a drying step for drying low rank coal of high moisture content at 30 C. to 50 C., it is possible to reduce the input heat value, so that the system is excellent in energy efficiency.

(25) (7) Since there is provided a dry distillation step for dry-distilling dried coal obtained by drying low rank coal the grain size of which is adjusted to 0.1 m to 5 mm to a moisture content of 20 mass % or less by the drying step, the specific gravity of the dried coal is reduced due to drying; thus, inclusive of the heat value for vaporizing the moisture content, it is advantageously possible to design the dry distillation furnace compact. Thus, the burden on the dry distillation furnace is small, and the equipment may be made small, so that the system is excellent in resource-saving efficiency.

(26) (8) Since there is provided a cooling bath for cooling the fixed carbon obtained in the dry distillation furnace, it is possible to solve the problems due to the tar component by fixing the tar component surfacing as a result of the cooling after the dry distillation within the fixed carbon; the system is excellent in stable operability.

(27) (9) Since there are provided a fluidized bed combustor in which hydrocarbon gas is used as the main fuel, and a power generation step in which there are provided a power generator operating a steam turbine with the main steam generated in the fluidized bed combustor and a condenser, it is possible to effectively utilize the exhaust heat by a heat medium moving between the fluidized bed combustor and the condenser. Further, since hydrocarbon gas and fixed carbon are produced by a dry distillation furnace, the system is excellent in resource-saving efficiency; since no indirect material such as oil is added, the system is light, which leads to excellent transportability; and it is possible to use subbituminous coal, brown coal, etc., which are of high moisture content and difficult to use in places other than the point of origin, in places other than the coal-producing region.

(28) (10) Since it is a complex system performing power generation using as the main fuel the hydrocarbon gas generated in the dry distillation furnace, it is possible to utilize the system for the production of fixed carbon through drying and dry distillation of low rank coal with the combustion heat of the hydrocarbon gas (volatile content) with the heating of the steam for power generation.

(29) Further, when the carbon dioxide gas is separated and recycled, the amount of N.sub.2 gas is considerably small, so that the concentration of the carbon dioxide gas is high, and it is possible to reduce the carbon dioxide gas separation energy, which leads to excellent energy-saving efficiency.

(30) (11) Since the dry distillation is performed at 350 C. to 500 C., the input heat value is small, making it possible to provide a power generation system excellent in energy efficiency. Further, the specific gravity of the dried coal is reduced due to drying, and, inclusive of the heat value for vaporizing the moisture, it is possible to design the dry distillation furnace compact, so that the system is excellent in resource-saving efficiency. Further, it is possible to make the dry distillation gas recycle system, etc., of the dry distillation furnace compact, so that the system is excellent in resource-saving efficiency.

(31) (12) Since there are provided a fluidized bed combustor in which hydrocarbon gas is used as the main fuel, and a power generation step in which there are provided a power generator operating a steam turbine with the main steam generated in the fluidized bed combustor and a condenser, it is possible to effectively utilize the exhaust heat by a heat medium moving between the fluidized bed combustor and the condenser. Further, since hydrocarbon gas and fixed carbon are produced by a dry distillation furnace, the system is excellent in resource-saving efficiency; since no indirect material such as oil is added, the system is light and transportation costs are low; and it is possible to use subbituminous coal, brown coal, etc., which are of high moisture content and difficult to use in places other than the point of origin, in places other than the coal-producing region; thus, the system is excellent in terms of usability.

(32) The fixed carbon is dry-distilled at 350 C. to 500 C., whereby the hydrocarbon gas (volatile content) is removed, and it is possible to ensure the conversion to high rank coal, making it possible to obtain a high rank coal of a fuel ratio of 2 or more, which helps to reduce the production cost of the apparatus itself; thus, the system is excellent in resource-saving efficiency and in energy-saving efficiency due to the small input heat value.

(33) (13) The combustion heat of the hydrocarbon gas (volatile content) may be used, together with the heating of the steam for power generation, for the production of fixed carbon through drying and dry distillation of low rank coal; thus, the system is excellent in resource-saving efficiency.

(34) Further, when the carbon dioxide gas is separated and recycled, the amount of nitrogen gas is considerably small, so that the concentration of the carbon dioxide gas is high, and it is possible to reduce the carbon dioxide gas separation energy, so that the system is even further excellent in resource-saving efficiency as a system.

(35) (14) Since the drying temperature in the drying step is 30 C. to 50 C., the reduction ratio of the drying time with respect to the input heat value for an increase in temperature is large, resulting in excellent energy efficiency.

(36) Further, the drying temperature is 30 C. to 50 C., and due to the excellent energy efficiency, it is possible to make the equipment volume compact; thus, the system is excellent in terms of cost.

(37) Further, due to the temperature range of 30 C. to 50 C., it is possible to perform heating to the drying temperature with the exhaust heat from the condenser, so that the system is excellent in energy efficiency.

(38) (15) Since each dry distillation mini-furnace is equipped with a pipe-shaped heating means, indirect heating by a high temperature heat medium is possible; and the temperature in the dry distillation furnace may be easily made uniform, so that the system is excellent in yield of fixed carbon. Further, there are provided dry distillation units each equipped with many rows of the dry distillation mini-furnaces, and a dry distillation furnace equipped with many rows of dry distillation units, so that the system is excellent in mass productivity.

(39) In addition, when the inner volume of the furnace is simply increased for mass production, it is difficult to make the temperature in the furnace uniform, and there are generated places where dry distillation partially progresses easily, etc.; and the yield of the high-quality fixed carbon is low.

(40) (16) There are provided dry distillation units each formed with many rows of dry distillation mini-furnaces, and a dry distillation furnace formed with many rows of dry distillation units, so that the system exhibits high rigidity; and it undergoes no deformation even when pressure is applied to the inside of the furnace due to generation of a volatile component in the dry distillation furnace or due to expansion of the raw material coal in the dry distillation furnace in the case where the interior of the furnace is not divided into rectangular sections; thus, the system is excellent in operation stability.

(41) (17) Since a pipe-shaped heating means is formed, it is possible to perform heating in a stable manner by means of high temperature heat medium such as steam, so that the system is excellent in operation stability.

(42) (18) The cooling bath for collecting fixed carbon is provided in the lower portion of the dry distillation furnace, so that it is possible to collect the product fixed carbon in a stable manner.

(43) (19) Due to the effective utilization of the exhaust heat, the system is excellent in energy-saving efficiency.

(44) (20) By using indirect heating utilizing the condenser exhaust heat of the power generator, it is possible to mitigate the latent heat loss in the dry distillation step, making it possible to make the system more compact.

(45) (21) Due to the arrangement using indirect heating utilizing the condenser exhaust heat, the heat medium employed is of high pressure and of high heat capacity, so that it is possible to make the apparatus compact, so that the system is excellent in terms of cost.

(46) FIG. 2 is a schematic diagram illustrating a fixed carbon production device according to an embodiment.

(47) In FIG. 2, 9A denotes a dry distillation furnace which has a dry distillation unit divided by a separating wall described below erected in the upper portion of the cooling bath, and dry distillation mini-furnaces divided by a partition plate described below provided in the dry distillation unit, steam piping and high temperature waste gas piping which are heated to a temperature of 500 C. to 600 C. are provided on the inner surface of the dry distillation furnace, the separating wall, and the partition plate, and dry-distills fed-dried brown coal at a temperature of 350 C. to 500 C.; 9a denotes a separating wall arranged vertically from the upper portion to the lower portion of the dry distillation furnace to divide the dry distillation furnace 9A into rectangular dry distillation units; 9b denotes partition plates arranged vertically from the upper portion to the lower portion of the dry distillation furnace to divide each dry distillation unit divided by the separating wall 9a into rectangular dry distillation mini-furnaces; 11A denotes a cooling bath for cooling and receiving the fixed carbon (product dry-distilled char); 46 denotes a fixed carbon production device consisting of the dry distillation furnace and the cooling bath; denotes dry distillation gas piping for recycling dry distillation gas produced through dry distillation which is provided in the upper portion or the lower portion; 48 denotes a dried brown coal feeding device for feeding into the dry distillation furnace dried brown coal obtained through drying of low rank coal to a moisture content of not more than 20 mass %; and 49 denotes an extraction port for the fixed carbon (product dry-distilled char).

(48) The fixed carbon production device of the power generation system of the present embodiment arranged as described above provides the following effects:

(49) (1) Each of the dry distillation mini-furnaces is equipped with a pipe-shaped heating means, so that indirect heating by a high temperature heat medium is possible; and it is easy to uniformly heat the interior of the dry distillation furnace, making it possible to prevent generation of heating spots. Further, there are provided dry distillation units each equipped with many rows of the dry distillation mini-furnaces, and a dry distillation furnace equipped with many rows of the dry distillation units, so that the device is excellent in rigidity and durability;

(50) (2) There are provided dry distillation units each formed with many rows of dry distillation mini-furnaces, and a dry distillation furnace formed with many rows of dry distillation units, so that the system exhibits high rigidity; and it undergoes no deformation even when pressure is applied to the inside of the furnace due to generation of a volatile component in the dry distillation furnace or due to expansion of the raw material coal in the dry distillation furnace in the case where the interior of the furnace is not divided into rectangular sections; thus, the device is excellent in operation stability;

(51) (3) A pipe-shaped heating means is formed on the separating wall and the partition plate of the dry distillation furnace, so that it is possible to perform heating in a stable manner with a high temperature heat medium such as steam; thus, the device is excellent in operation stability;

(52) (4) Since a cooling bath for collecting fixed carbon is provided in the lower portion of the dry distillation furnace, it is possible to cool the fixed carbon reformed in the dry distillation furnace and to collect the fixed carbon (product dry-distilled char) in a stable manner;

(53) (5) Since the dry distillation is performed at 350 C. to 600 C., the hydrocarbon gas (volatile content) is removed, and it is possible to convert to high rank coal, making it possible to obtain a high rank coal of a fuel ratio of 2 or more;

(54) (6) Since it is possible to perform the dry distillation at a low temperature of 350 C. to 600 C., the device is excellent in cost-saving efficiency in terms of the cost of the device itself and the input heat value; and

(55) (7) Since it is possible to perform the dry distillation while retaining heavy oil, there are no problems such as the clogging of the reactor.

Experiment Example 1

Dry Distillation Test

(56) In experiment example 1, the dry distillation temperature of the moving bed indirect heating dry distillation furnace was examined.

(57) FIG. 3 is a schematic view of the simulated moving bed indirect heating dry distillation furnace used for collecting test data of the present embodiment.

(58) In FIG. 3, 50 denotes a simulated moving bed indirect heating dry distillation furnace; 51 denotes a container furnace filled with a brown coal specimen (which was obtained through pre-heating and drying Loy Yang brown coal (raw coal) in the atmosphere and at room temperature to reduce its moisture content to around 20 mass %, setting the grain sizes to 0.3 mm to 0.5 mm through crushing/classification, drying the resultant coal in an inert gas atmosphere at 110 C., and removing the moisture therefrom) and partitioned in the length direction and the perpendicular direction (horizontal plane direction) with a SUS mesh; 51a denotes an inert gas feeding port through which N.sub.2 gas is caused to flow in at a rate of 200 ml/min to create an inert gas atmosphere in the container furnace 51; 51b denotes an inert gas outlet for the inert gas input from the inert gas feeding port 51a; 52 denotes an electric furnace arranged in many stages in order to form a temperature distribution; 53 denotes a motor for moving the container furnace 51 inside the electric furnace 52 at a constant speed for spuriously preparing the data regarding the carbon flowing down in the furnace; and 54 denotes the moving direction of the container furnace.

(59) The inert gas flows from the inert gas feeding port 51a toward the inert gas outlet 51b in FIG. 3 (from the upper side toward the lower side in FIG. 3).

(60) The simulated moving bed indirect heating dry distillation furnace 50 is a device simulating the brown coal conversion characteristics and the gasification characteristics in the dry distillation. The container furnaces 51 of cylindrical reactors formed of SUS are fixed in series in 15 stages, and these are raised by the motor 53 in the direction of the moving direction 54 from the lower portion toward the upper portion of the vertical electric furnaces 52 arranged in a number of stages, whereby there was obtained the test data when the brown coal filled in the container furnace 51 flowed down from the upper portion to the lower portion of the moving bed. From the upper side in FIG. 3, the container furnaces 51 were numbered as the first, second, . . . , to 15th container. There were provided nine electric furnaces 52; and the first through fourth electric furnaces as ordered from the lower side in FIG. 3 were set to 165 C., the fifth furnace was set to 300 C., the sixth furnace was set to 400 C., the seventh furnace was set to 500 C., the eighth furnace was set to 600 C., and the ninth furnace was set to 700 C., respectively. It is noted that the container furnaces 51 were raised at a rate of 6.9 mm/min within the electric furnaces 52. The temperature rise rate at this time of the container furnaces 51 was about 10 C./min. Of the fifteen container furnaces 51, the container furnaces 51 which have passed the electric furnace uppermost portion were the first through sixth container furnaces 51.

(61) FIG. 4 and (Table 1) are graphs showing the dry-distilled coal analysis results according to the dry distillation temperatures. More specifically, FIG. 4 shows the solid yields of the respective containers obtained based on the mass of the solid remaining after the completion of the experiment using the simulated moving bed indirect heating dry distillation furnace 50 of FIG. 3.

(62) At this time, the first through sixth of the container furnaces 51 have passed the electric furnaces; the seventh through eleventh container furnaces 51 correspond to 200 C. to 595 C. of the thermal decomposition zone; and the 12th to 15th container furnaces 51 are the portions heated at 165 C. and they are at a temperature of about 140 C.

(63) The carbide yield at the first container furnace 51 was 56 mass %; the carbide yield gradually increased from the second to the sixth container furnaces 51, i.e., the lower the stage; and the yield attained 58.7 mass % at the sixth container furnace 51. This resulted from the volatile component containing heavy oil generated from the upper stage container coming into contact with the brown coal carbide and half-carbide of the lower stage, with the carbide yield increasing due to sorption of the heavy oil and co-carbonization of the heavy oil and the brown coal. Further, from the 12th container furnace 51 onward, there was recognized an increase in weight by 10% to 20% of deadweight probably attributable mainly to the sorption of the heavy oil. On the downstream side of the reactor (the 12th to 15th container furnaces 51), the production gas and the condensation component were recycled, and the recycle rate of these generated products was 99% or more. As a result of the analysis of the recycled condensation component, it was found that the high boiling point heavy oil condensed due to the presence of a low temperature portion in the furnace; further, it is possible to perform selective production of light oil components through supply of heavy oil due to the brown coal particles present here; and, as shown in FIG. 4 and (Table 1), in the temperature range of 200 C. to 595 C., dry distillation rapidly progressed in the moving bed indirect heating dry distillation furnace, making it possible to retain the heavy oil component in the fixed carbon.

(64) TABLE-US-00001 TABLE 1 Container furnace number 1 2 3 4 5 6 7 8 Solid yield 56 56.4 56.9 57.5 57.9 58.7 59.3 61.4 (mass %) Container furnace number 9 10 11 12 13 14 15 Solid yield 65.7 72.4 88.9 107.9 112.4 110.4 108.9 (mass %)

Experiment Example 2

Evaluation Test Through Thermogravimetric Analysis

(65) In experiment example 2, the dry distillation temperature was examined through thermogravimetric analysis.

(66) FIG. 5, (Table 2), and (Table 3) are graphs showing the results of the dry-distilled coal thermogravimetric analysis according to the dry distillation temperatures. More specifically, in order to check the dry distillation temperature through thermal decomposition of brown coal, Loy Yang brown coal (raw coal) was pre-heated and dried at room temperature and in the atmosphere to reduce its moisture content to around 20 mass %; then, its grain sizes were set to 0.3 mm to 0.5 mm through crushing/classification, and the coal was dried in an inert gas atmosphere at 110 C. to remove moisture therefrom; the resultant coal was measured by using a thermogravimetric analysis apparatus (EXSTAR TG/DTA 6000 manufactured by SII Nanotechnology Inc.) to obtain the following results.

(67) As shown in FIG. 5, (Table 2), and (Table 3), it is recognized that the brown coal weight began to decrease at around 350 C., with the dry distillation being conspicuous from this temperature. Further, in a stationary bed dry distillation furnace, a similar specimen was dry-distilled in a nitrogen stream at 500 C., 550 C., 600 C., and 650 C., with the temperature rise rate being 10 C./min, and the retaining time at the peak temperature being zero seconds. The relationship between the fixed carbon yield and the temperature at this time is plotted in FIG. 5. By checking the graph, it is understood that the results of the thermogravimetric analysis and the temperature definition in the dry distillation furnace are in a satisfactory correlationship. The results of the dry-distilled coal thermogravimetric analysis in FIG. 5 are plotted in (Table 2), and the relationship between the fixed carbon yield and temperature in FIG. 5 is plotted in (Table 3).

(68) TABLE-US-00002 TABLE 2 Temperature ( C.) 200 300 400 500 600 700 800 Weight change 0.99 0.95 0.85 0.7 0.62 0.57 0.53 amount (mass %)

(69) TABLE-US-00003 TABLE 3 Peak temperature ( C.) 500 550 600 650 Yield of fixed carbon 0.71 0.67 0.63 0.6

Experiment Example 3

High Rank Conversion Temperature Demonstration Test

(70) In experiment example 3, the requisite temperature for conversion from low rank coal to high rank coal was examined.

(71) FIG. 6 and (Table 4) are graphs showing temperature changes in brown coal inside the dry distillation furnace. More specifically, Loy Yang brown coal (raw coal) was placed in a horizontally installed tubular furnace with N.sub.2 gas circulating therethrough; in this state, the in-furnace temperature was raised to each measurement temperature, and the temperature change time at that time and each temperature were measured.

(72) As shown in FIG. 6, it is understood that even after the moisture had vaporized at around 100 C., the temperature increased gradually; even when the set temperature was 300 C., there was a latent heat component, which shows that conversion to high rank coal occurred.

(73) TABLE-US-00004 TABLE 4 Reaction time (min) 1 2 3 4 5 6 7 8 9 10 Set temperature 300 Specimen 88 93 93 104 133 182 229 259 276 287 ( C.) 350 temperature ( C.) 96 95 95 124 187 254 296 319 333 341 400 96 115 225 315 352 371 381 386 390 392 500 97 111 265 381 453 489 500 500 500 500 600 101 127 376 525 565 578 584 588 590 592 700 114 462 626 661 675 682 685 688 690 691 800 102 464 715 753 767 774 778 782 784 786

Experiment Example 4

Dry Distillation Temperature Effect Test

(74) In experiment example 4, dry distillation temperature and the performance of the resultant fixed carbon were examined.

(75) FIG. 7 and (Table 5) are graphs showing changes in various combustion-related components of the fixed carbon at the brown coal dry distillation processing temperatures. More specifically, Loy Yang brown coal (raw coal) was pre-heated and dried at room temperature and in the atmosphere, reducing its moisture content to around 20 mass %; the resultant coal was placed in a horizontally installed tubular furnace with N.sub.2 gas circulating therethrough; in this state, the in-furnace temperature was raised to 400 C., 600 C., 700 C., and 800 C., and the inherent moisture, volatile content, ash, fixed carbon yield (%), and the fuel ratio at that time were measured.

(76) As shown in FIG. 7 and (Table 5), in the coal processed at 400 C., the fuel ratio was 2.5, thus showing that there has been realized a fuel ratio on the order of bituminous coal like Newlands coal.

(77) TABLE-US-00005 TABLE 5 Processing temperature ( C.) 400 600 700 800 Newlands coal Inherent moisture (mass %) 6.3 8.4 10.3 14.6 2.7 Volatile content (mass %) 26.3 13.0 10.2 7.3 27.3 Ash (mass %) 2.5 3.3 3.6 3.7 14.7 Fixed carbon (mass %) 64.8 75.3 76.0 74.4 55.3 Fuel ratio 2.5 5.8 7.5 10.2 2

Experiment Example 5

Drying Temperature Effect Test

(78) In experiment example 5, the drying temperature was examined.

(79) FIG. 8 and (Table 6) are graphs illustrating the moisture content in low temperature drying according to temperature and time.

(80) As the specimen, there was employed Loy Yang brown coal (raw coal); the time and the weight of each specimen when the humidity was set to 40% were measured, using the temperatures in a thermo-hygrostat (IW 222 manufactured by Yamato Scientific Co., Ltd.) as the respective measurement conditions.

(81) As shown in FIG. 8 and (Table 6), it is understood that the requisite time is greatly reduced for drying at 30 C. and for drying at 40 C. When the temperature is increased, the drying time is shortened; however, as compared with the room temperature condition, the ratio at which the drying time is shortened is higher when the temperature is around 30 C., which is somewhat higher than room temperature. Thus, when the drying temperature is high, the advantage attained is rather small as compared with the heat value consumed in order to raise the temperature. (The degree by which the drying time is shortened is reduced.) Thus, by performing drying at about 40 C., the input heat value is minimized, it is possible to perform the drying processing at high efficiency. Further, it is understood from this fact that the temperature range of 30 C. to 50 C. is most preferable. When the temperature is lower than 30 C., the drying time is too long, which undesirably results in an increase in the size of the processing device; when the temperature is 50 C. or more, the temperature difference is too small to use the exhaust heat (60 C. to 90 C.) from the condenser; thus, the equipment/system is increased in size in order to warm the dryer; further, it is necessary to add sub equipment such as a heat pump in order to raise the temperature, which leads to inferior resource-saving efficiency and is not desirable.

(82) TABLE-US-00006 TABLE 6 Drying temperature ( C.) 30 40 50 60 70 Time elapsed (min) Moisture in 50 180 120 90 70 45 brown coal (%) 40 330 210 150 120 90 30 420 270 195 160 120 20 600 360 270 220 150

(83) Next, regarding the power generation system according to the present embodiment, the heat balance and the material balance were obtained through computer simulation. The condition was as follows: as the low rank coal, there was used unprocessed brown coal produced in Victoria. The initial moisture of the brown coal was 60 mass %, the moisture of dried brown coal after the drying in the drying unit 3 was 20 mass %, the fuel ratio was 1.2, and the power generation efficiency was 30%.

(84) FIG. 9 shows the experiment results, illustrating the heat balance and the material balance in the present embodiment.

(85) As shown in FIG. 9, the heat value of the raw material brown coal is 2400 kcal/kg, and the heat value of the fixed carbon is 7000 kcal/kg, so that, by performing drying and dry distillation, the heat value per weight is increased by about 2.9 times, thus heat value efficiency is excellent. It is possible to produce a fixed carbon which is solid fuel of about 2.9 times the heat value; further, by vaporizing the moisture and performing dry distillation, it is possible to reduce the weight of the raw material coal, which is 38,500,000 tons, to 26%, which is 10,030,000 tons, which leads to excellent transportability and makes it possible to convey the coal to a place other than the coal-producing region, effectively using the coal as solid fuel.

(86) Further, the present inventors have extensively studied how to effectively utilize low rank coal such as brown coal, finally completed a complex system making it possible to produce char and raw material gas from low rank coal at high efficiency, which was filed as International Application No. PCT/JP2012/056706. In this complex system, fixed carbon is used as the main fuel. In this case, the fixed carbon is fed as the requisite input heat for the drying and dry distillation, so that the requisite energy for generating the fixed carbon itself is lost.

(87) According to the present invention, after further careful study, power generation is performed by using hydrocarbon gas as the main fuel, and fixed carbon is produced, so that it is possible to produce fixed carbon at high efficiency, so that the system is excellent in energy-saving efficiency. The fixed carbon produced allows power generation like high rank coal such as Newlands coal. Further, as compared with the raw material coal, it is possible to reduce the weight of the coal at that time to about (26%), so that it is possible to convey fixed carbon at about four times the amount by a similar means; thus, the system is excellent in energy-saving efficiency and transportability, making it possible to use the coal at a power generation plant, etc., near the place where the power is consumed, i.e., at a place other than the coal-producing region, so that the system is excellent in terms of the utilization of energy.

(88) Further, it is understood from FIG. 9 that the tar component and the by-product gas generated are utilized in terms of heat for the power generation step and the drying step, utilizing the exhaust heat of the condenser of the power generation step; thus, the exhaust heat is utilized by as much as 26.5% by the heat value base for the drying step and the dry distillation step, and by as much as 4.5% by the heat value base for the power generation step, thus building a high efficiency power generation system.

INDUSTRIAL APPLICABILITY

(89) According to the present invention, low rank coal is dried in the drying step, dry distillation is performed in the dry distillation step with the combustion heat of the combustion step while moving the dry distillation furnace; power generation is performed by using the hydrocarbon gas obtained through dry distillation as the main fuel, and, by recycling fixed carbon obtained through dry distillation, it is possible to use the fixed carbon as solid fuel that may be transported overseas. Further, the exhaust heat of the combustion step is supplied to the drying step and the dry distillation step to utilize it for temperature control and to perform the circulation or recycle of CO.sub.2 gas and power generation. As a result, power generation and the production of solid fuel are combined to provide a power generation system allowing full use of CO.sub.2, electricity, and solid fuel.

REFERENCE SIGNS LIST

(90) 1 Power generation system

(91) 2 Mining/coal-conveying equipment

(92) 3 Dryer

(93) 4 Dryer heat exchange unit

(94) 5 Dust collector

(95) 6 Preprocessing device

(96) 7 Preprocessing device heat exchange unit

(97) 8 Dried coal bunker

(98) 9, 9A Dry distillation furnace

(99) 9a Separating wall

(100) 9b Partition plate

(101) 10 Dry distillation furnace heat exchange unit

(102) 11, 11A Cooling bath

(103) 12 Cooling bath heat exchange unit

(104) 13 Fluidized bed combustor

(105) 14 Combustor main steam heat exchange unit

(106) 15 Reheated steam heat exchange unit

(107) 16 Cyclone

(108) 17 Ash processing device

(109) 18 Combustion air preheater

(110) 19 Combustion air preheater heat exchange unit

(111) 20 CO.sub.2, separation device

(112) 21 Chimney

(113) 22 CO.sub.2 supply unit

(114) 23 CCS

(115) 24 Forced draft fan

(116) 25 O.sub.2 separator

(117) 26 O.sub.2 supply unit

(118) 27 Pre-heated O.sub.2 supply unit

(119) 28 N.sub.2 supply unit

(120) 29 Dry air forced draft fan

(121) 30 Inert gas preheater

(122) 31 Pre-heated N.sub.2 supply unit

(123) 32 Steam turbine

(124) 33 Condenser

(125) 34 Power generator

(126) 35 Cooling tower

(127) 36 Condenser exhaust heat supply unit

(128) 37 Steam drive type water supply pump

(129) 38 Water supply unit

(130) 39 Water supply heater

(131) 40 Heated water supply unit

(132) 41 Main steam supply unit

(133) 42 Reheated steam supply unit

(134) 43 Reheated steam return unit

(135) 44 Reheated steam dry distillation furnace supply unit

(136) 45 Reheated steam preprocessing device supply unit

(137) 46 Fixed carbon production device

(138) 47 Dry distillation gas piping

(139) 48 Dried brown coal feeding device

(140) 49 Extraction port for fixed carbon

(141) 50 Simulated moving bed indirect heating dry distillation fur

(142) 51 Container furnace

(143) 51a Inert gas feeding port

(144) 51b Inert gas outlet

(145) 52 Electric furnace

(146) 53 Motor

(147) 54 Moving direction of container furnace

(148) 55 Fixed carbon

(149) 56 Dry distillation unit

(150) 57 Dry distillation mini-furnace

(151) 58 Pipe heating means