Title of Invention

AN IMPROVED SYSTEM TO PRODUCE LOW ASH CLEAN COAL AND SUPERCLEAN COALS

Abstract

An improved system to produce low ash clean coal and superclean coal from high ash coals, comprising: at least a feed-preparation zone, an extraction zone, a solvent recovery zone, a precipitation zone, and an organic water separation zone, the feed-preparation zone (C) enabling mixing of specific quanti ties of coal (A), and solvent (B) to produce a coal slurry; the extraction zone allows extraction of the coal-solvent mixture through maintaining the temperature and pressure inside the reactor at prepderemined level, and allowing a varying residence time of the coal slurry corresponding to the process parameters, a filter unit (D) for filtrating the extracted coal-solvent mixture; a flash-unit (F) for receiving the filtrate from the filter unit (D) and allowing a recovery of the solvent (B) in the flash-unit (F), a sudden-pressure-drop in the flash-unit allowing a boiling off the solvent (B) thereby making it possible to recover a substantial portion of the solvent (B); and a storage means to receive the residue (E) fromthe filter unit (D) for storing,

Full Text

FIELD OF THE IVNETION The invention relates to an improved system to produce low ash clean coal from high ash coals for metallurgical applications. The invention further relates to a process to produce low ash clean coal with economic yield including producing of superclean coal from high ash coal. BACKGROUND OF THE INVENTION The known process operation involves chemical beneficiation of coal by dissolving organic matter of coal in various organic solvents. As coal constitutes a heterogeneous mixture of organic and inorganic components, a step of solvolysis of the coal varies corresponding to its constituents, maturity, and structural characteristics. Main advantages of the solvolysis process are i) ease of recovery of the solvent in the main process stream, ii) a higher solvolytic efficiency of the recovered solvents as compared to that of fresh solvent, Hi) 95-98% recovery of the solvent, iv) improved coking properties of clean coal, and v) availability of industrial organic solvents. However, the operating cost of this process is high because of high cost of solvents and energy requirements in the process. Organo-refining or, solvent-refining, or, solvent extraction of coal is a well- established technology. Abundant literature is available on the subject. However, the primary objective in most of those cases is to provide a process to produce an ultra clean coal or a super clean coal with ash content less than 0,2%. The ahs content of this parent coal ( Run of Mine) is 25%. Exploratory study revealed that it is possible to extract 50% of the parent coal through this process of extraction of coal under reflux conditions at atmospheric pressure. The coa) contains almost 4% ash. The yield and the ash content of the super clean coal as obtainable is satisfactory according to the study reports. However, in an industrial set up to implement the studied process, the main concerning factor apart from yield is the ultimate economic viability of the process. As the process consumes a significant amount of heat for extraction, recovery of solvent is possible only after consumption of a large amount of heat, the combined effect of two heat consumption, leads the process towards uneconomic. Now if the said two heat consumptions are arranged on priority basis, then heat consumption for extraction is to be considered first. This is because the extraction is solely dependent upon the extraction temperature. This is the reason that this process is often called as thermal extraction process. So only the heat required for solvent recovery is left behind for minimization. Effective or optimized process of solvent recovery could be the only option to establish the process-feasibility. OBJECTS OF THE INVENTION It is therefore an object of the invention to propose an improved process to produce low ash clean coal from high-ash coal, maintaining the process economy. Another object of the invention is to propose an improved process to produce low ash clean coal from high-ash coal, which minimizes the heat-requirement for solvent recovery. A further object of the invention is to propose an improved process to produce low ash clean coal from high-ash coal, which enables higher extraction from the parent coal. A still further object of the invention is to propose a system to produce low-ash clean coal from high-ash coal. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING Figure - 1 - schematically shows a system for industrially implementing the improved process according to the invention. SUMMARY OF THE INVENTION The system of the invention has five different zone namely, (i) feed preparation zone (ii) extraction zone (iii) solvent recovery zone (iv) Precipitation zone (v) Organic water separation zone. Coal and solvent including co-solvent are mixed thoroughly in a coal-feed preparation zone. Coal slurry is then pumped into a reactor. In the reactor a temperature around 250° to 350°C is maintained by circulating hot thermic fluid. A high pressure is maintained by inducing a pressure about 3 to 4 atm. inside the a reactor. The high pressure elevates the boiling point of the solvent. Residence time in the reactor may vary form 1 h to 1.5 h which depends on the techno economics of the process and its specific requirement. Extracted coal- solvent mixture is then passed through a filter unit and the filtrate is then passed to a flash unit. In the flash unit, due to the sudden pressure drop in pressure, at least 70% of the solvent gets boiled off as the temperature of the solvent is in the reactor is much higher than the atmospheric boiling point of the solvent. Thus, a recovery of 70% of the solvent without introducing any external heat source can be achieved, as the reactor is maintained at a high pressure and temperature for flashing. The residue from the filter unit is taken off and stored for latter use. The filtrate contains little but coal extracts which is fed to the water in a precipitating tank. In the precipitating tank, the coal gets precipitated as water acts as an anti solvent. This slurry becomes filtered by another rotary drum filter and the super clean coal is collected as residue. The fi\trate contains water and organic mixture which is fed to a distillation unit and water and organic mixtures is separated. This way 50% yield of clean coal having less than 4% ash is produced. As the solvent of use are organic and are flammable in nature, it may catch fire in contact with oxygen at high temperature. Therefore, there a is provision for Nitrogen flashing in the reactor and the Rotary drum filter unit. DETAIL DESCRIPTION OF THE INVENTION Figure - 1 shows the inventive system. In the system, coal (A), and solvent (B) are mixed thoroughly in a feed - preparation zone of a reactor (C) to produce a coal slurry. The coal slurry is then extracted in the reactor (C). In the extraction unit (C), the temperature is raised (about 250 °C) to facilitate the extraction at a high pressure. The range of temperature and pressure variation is (250 °C to 300 °C) and ( 3 atm. to 10 atm.). At the high pressure boiling of the liquid gets shifted to higher zone. Due to the thermal impact, the coal structure is relaxed and the process of extraction is enhanced. After extraction, the total slurry is then fed to a centrifuge filter (D), which is capable of withstanding high pressure and temperature. After filtration, the extract is then allowed to be flushed in a flush chamber (F) where due to sudden release of pressure, the solvent vapor comes out. As the extract remains much above than its boiling point (202 °C), at least 70% of the solvent is flushed out. The solvent vapor is then cooled and collected in a vessel (G) and sent for recycling. This way evaporation of the solvent is eliminated and a large amount of energy is saved. The main advantages of the invention achieved 1. Generally solvent recovery is done by an evaporator which is normally used instead of a flush chamber (F). But according to the invention, the extraction temperature and pressure is used for recovery of atteast 70% solvent which could have been otherwise achieved by a costly evaporator. The invention thus eliminates the requirement of a costly equipment, and also helps to avoid an energy intensive operative. The flush chamber is a simple vessel which gives same amount of solvent without adding extra heat into the system. Main novelty of the process Elimination of an evaporator from the process operation by a flash chamber including maintaining a reactor Temperature and Pressure, according to the invention allows atleast 70% of the solvent be recovered. WE CLAIM 1. An improved system to produce low ash clean coal and superclean coal from high ash coals, comprising : - at least a feed-preparation zone, an extraction zone, a solvent recovery zone, a precipitation zone, and an organic water separation zone, the feed-preparation zone (C) enabling mixing of specific quantities of coal (A), and solvent (B) to produce a coal slurry; - the extraction zone allows extraction of the coal-solvent mixture through maintaining the temperature and pressure inside the reactor at prepderemined level, and allowing a varying residence time of the coal- slurry corresponding to the process parameters, - a filter unit (D) for filtrating the extracted coal-solvent mixture; - a flash-unit (F) for receiving the filtrate from the filter unit (D) and allowing a recovery of the solvent (B) in the flash - unit (F), a sudden- pressure-drop in the flash-unit allowing a boiling off of the solvent (B) thereby making it possible to recover a substantial portion of the solvent (B); and - a storage means to receive the residue (E) from the filter unit (D) for storing, 2. The system as claimed in claim 1, further comprising: - a precipitating tank (H) having water therein for precipitating the further coal-extracts received as the filtrate; - a second filter unit for filtering the slurry received from the precipitating tank (H) which allows collection of super clean coal as a residue (I); and - a distillation unit (J) which receives water and organic mixture from the second filter unit for separation of water and the organic mixture. 3. The system as claimed in claim 1, wherein the reactor (C) is maintained at a temperature between 250 °C to 350 °C, and wherein a pressure between 3 atm to 4 atm is induced and maintained inside the reactor (C). 4. The system as claimed in claim 1, wherein the coal slurry is subjected to a residence time inside the reactor (C) between 1 hour to 1.5 hours. 5. The system as claimed in claim 1, wherein the flash unit (F) enables recovery of at least 70% of the solvent due to sudden pressure drop leading to vaporization of the solvent which after cooling off is collected in a vessel (G). 6. A process to produce low ash clean and superdean coa! from high ash coals in a system as claimed in claim 1, the process comprising the steps of: - - providing coal (A), solvent (B), and co-solvent at predetermined quantity corresponding to the technical capacities of the system; - mixing the coal (A), solvent (B), and the co-solvent in the reactor (C) of the system to produce coal slurry; - pumping-in the produced coal slurry in the feed-zone of the reactor (C); - inducing a pressure and temperature so as to maintain the reactor (C) at a specified temperature and pressure and allowing a prefixed residence time of the coal slurry; - extracting the coal-solvent mixture and passing the mixture to a filter unit (D); - passing the filtrate from the filter unit (D) to a flash-unit (F) which enables to generate a sudden pressure-drop of the extracted mixture inside the flash unit (F); - recovering a substantial quantity of the solvent (B) which gets vaporized, and collecting the solvent in a vessel (G) after cooling off the vapor; and - storing the residue (E) from the filter unit (F). 7. The process as claimed in claim 6, further comprising: - feeding the filtrate containing still-remaining coal extracts into a precipitating tank (H) having water therein; - passing the coal slurry from the tank (H) to a rotary drum filter for filtering; - collecting super clean coal as a residue (I) from the rotary drum filter; and - separating the filtrate in a distillation unit (J) so as to separate water and the organic mixture containing the filtrate. 8. An improved system to produce low ash clean coal and superdean coal from high ash coals, as substantially described and illustrated herein with reference to the accompanying drawings. 9. A process to produce low ash clean and superdean coat from high ash coals as substantially described and illustrated herein with reference to the accompanying drawings. An improved system to produce low ash clean coal and superclean coal from high ash coals, comprising: at least a feed-preparation zone, an extraction zone, a solvent recovery zone, a precipitation zone, and an organic water separation zone, the feed-preparation zone (C) enabling mixing of specific quanti ties of coal (A), and solvent (B) to produce a coal slurry; the extraction zone allows extraction of the coal-solvent mixture through maintaining the temperature and pressure inside the reactor at prepderemined level, and allowing a varying residence time of the coal slurry corresponding to the process parameters, a filter unit (D) for filtrating the extracted coal-solvent mixture; a flash-unit (F) for receiving the filtrate from the filter unit (D) and allowing a recovery of the solvent (B) in the flash-unit (F), a sudden-pressure-drop in the flash-unit allowing a boiling off the solvent (B) thereby making it possible to recover a substantial portion of the solvent (B); and a storage means to receive the residue (E) fromthe filter unit (D) for storing,

Documents:

1194-KOL-2009-(15-01-2014)-CLAIMS.pdf

1194-KOL-2009-(15-01-2014)-CORRESPONDENCE.pdf

1194-KOL-2009-(15-01-2014)-FORM-1.pdf

1194-KOL-2009-(15-01-2014)-FORM-2.pdf

1194-kol-2009-abstract.pdf

1194-kol-2009-claims.pdf

1194-KOL-2009-CORRESPONDENCE-1.1.pdf

1194-kol-2009-correspondence.pdf

1194-kol-2009-description (complete).pdf

1194-kol-2009-drawings.pdf

1194-KOL-2009-FORM 1-1.1.pdf

1194-kol-2009-form 1.pdf

1194-KOL-2009-FORM 18.pdf

1194-kol-2009-form 2.pdf

1194-kol-2009-form 3.pdf

1194-kol-2009-gpa.pdf

1194-KOL-2009-PETITION UNDER RULE 137.pdf

1194-kol-2009-specification.pdf

abstract-1194-kol-2009.jpg