Title of Invention

A METHOD FOR CONTROLLED PREPARATION OF COAL BLEND FEED FOR COKE OVEN TO AVOID CHUTE-JAMMING.

Abstract

TITLE: A METHOD FOR CONTROLLED PREPARATION OF COAL BLEND FEED FOR COKE OVEN TO AVOID CHUTE-JAMMING. The present invention relates to a method for controlled preparation of coal blend feed for coke oven such as to avoid problems of chute jamming due to excessive moisture content in feed coal and a system for addition of oil-water emulsion through multiple spray nozzles on coal blend for coke oven. The system involves controlled feeding of an initial quantity of oil in a mixing tank by measuring and controlling the flow rate and by passing through strainers to remove any foreign particles; and also feeding an initial quantity of water depending upon the water content by measuring and controlling the flow rate and passing through strainers to remove any foreign particles; pre-mixing of the oil and water emulsion thus obtained takes place in said mixing tank by counter-flow principle. A recirculation pump subjects the pre-mixed water and oil emulsion to intense mixing. An emulsion pump operatively supply the emulsion mixture from said mixing tank to the spray points over the coal blend feed.

Full Text

Introduction in the Field of Invention: This invention relates to a method for controlled preparation of coal blend feed for coke oven such as to avoid problems of chute jamming due to excessive moisture content in feed coal and a system for addition of oil-water emulsion through multiple spray nozzles on coal blend for coke oven. Prior Art and the drawbacks: In selective crushing units of a running Steel Plant, coal is fed from silos to primary crusher units through two numbers of conveyors. The system was designed for maximum moisture level of 8.5% in feed coal. During monsoon, the moisture level in coal increases beyond 8.5%, leading to problems such as jamming of chutes and classifiers. Due to jamming, sometimes the classifiers are bypassed in order to supply coal to service bunkers continuously. This causes deterioration of coal crushing and in turn coke quality. The performance of the selected crushing unit deteriorated especially during monsoon period, because of poor fluidization of coal due to high moisture content in feed coal. Objects of the Invention: It is therefore an object of this invention to propose a method and system for system for controlled preparation of coal blend feed for coke oven such as to avoid problems of chute jamming by way of selective addition of oil-water emulsion to coal for improving the performance of coal feed supply. It is another object of the invention to propose a method and system for system for controlled preparation of coal blend feed for coke oven which will overcome the problem of chute jamming prevalent in the known systems; the jamming is primarily due to high moisture content above designed value in coal feed during monsoon period. Brief Description of the Invention: According to the basic aspect of the present invention there is provided a method for controlled preparation of coal blend feed for coke oven such as to avoid problems of chute jamming and the like comprising: controlled feeding an initial quantity of oil in a mixing tank by measuring and controlling the flow rate and by passing through strainers to remove any foreign particles; feeding an initial quality of water in the mixing tank depending upon the water content by measuring and controlling the flow rate and by passing through strainers to remove any foreign particles; pre-mixing the oil and water emulsion thus obtained in said mixing tank by counter-flow principle; subjecting the pre-mixed water and oil emulsion to intense mixing by means of a recirculation pump; operating an emulsion pump to supply the emulsion mixture to from said mixing tank to the spray points over the coal blend feed; In this invention, the water tank is preferably installed at ground level such that feed water is tapped from a main water supply line and it is controlled through a manually operated gate valve. For the sake of convenience, the oil storage tank is installed below the ground level for fire safety norms and oil is fed into the underground oil tank by gravity flow from a supply tanker. The flow rate of water into the mixing tank is controlled by means of a glove valve and the rate of water is preferably controlled by having the globe valve in a return line. The flow rate of oil into the mixing tank is controlled by means of a globe valve and the rate of oil is preferably controlled by having the globe valve in a return line. The oil and water are initially mixed in the mixing tank by counter flow principle and the mixing is intensified by re-circulation. In this method, for efficient results, preferably, the initial quantity of oil is filled in the mixing tank to the required level indicated by a low level sensor, where after the oil feed is stopped and the water feed is started until the level reached a pre-determined height, where after the feed of water is stopped. A re-circulation of the initially formed water-oil emulsion is effected as long as necessary to obtain the uniform mixture of oil-water as emulsion. The final emulsion is withdrawn from the mixing tank and fed to spray nozzles for spraying the emulsion on necessary beds of coal charge. In a preferred embodiment, the continuity of emulsion formation and spraying on the coal charge is maintained by feeding water and oil simultaneously into the mixing tank once the level of the emulsion being withdrawn reaches a pre-determined level in the tank. In a most preferred embodiment of the invention, the emulsion is sprayed on the coal charge being fed to one or more primary crushers and also on the coal charge from one or more secondary crushers to the respective pneumatic classifiers. According to another aspects of the invention there is provided a system for controlled preparation of coal blend feed for coke oven such as to avoid problems of chute jamming and the like comprising: pump and motor means operatively connected to an oil storage for controlled feeding of an initial quantity of oil into a mixing tank including means for measuring and controlling the flow rate and strainers to remove any foreign particles; pump and motor means operatively connected to a water storage unit for controlled feeding an initial quality of water in the mixing tank depending upon the oil content including means for measuring and controlling the flow rate and strainers to remove any foreign particles; means for pre-mixing the oil and water emulsion thus obtained in said mixing tank by counter-flow principle; a recirculation pump means for subjecting the pre-mixed water and oil emulsion to intense mixing; an emulsion pump adapted for controlled supply of the emulsion mixture from said mixing tank to the spray points over the coal blend feed . The pump with motor associated with water storage tank and the oil storage tank are respectively provided with necessary gate valves for isolation and removal for maintenance purpose during breakdown. There is provided a strainer element immediately after the water storage tank and oil storage tank in their respective water and oil withdrawal pipes for removing any foreign materials. There is provided flow measuring means both in the water and oil feed pipe in the mixing tank and the said means is preferably a rotameter. The re-circulation means in the mixing tank is a pipe means and is provided with pump and motor and necessary gate valve. The emulsion withdrawal means in the mixing tank is a pipe means and is provided with pump and motor and necessary gate valve. In a preferred embodiment, the emulsion withdrawal pipeline is provided with a strainer immediately after the mixing tank to remove any unwanted material. The emulsion withdrawal pipe means is provided with a return line with a globe valve for re-circulating. Th emulsion withdrawal pipe means is provided with a rotameter at its leading end to measure the quantity of emulsion sent for spraying and controlling the flow of emulsion. In this embodiment, there is provided one or more location for spraying the emulsion on the coal charge wherein the coal charge passes through is the transfer chute from the conveyor belt to the coal crusher. In a preferred embodiment, there are provided four different locations, which are transfer chutes from the conveyor belts to the primary crusher and transfer chutes from the secondary crusher to the pneumatic classifier and there are provided two primary crushers and two pneumatic classifiers. The mixing tank is preferably provided with three level indictors, namely a low level sensor meant for indicating the initial quantity of oil filled in the mixing tank, a high level sensor meant for indicating the level of initial quantity of water and oil fed into the mixing tank and an intermediate level sensor for indicating the level of emulsion as it reaches that level at the time of withdrawal of emulsion from the mixing tank. The three sets of level indicators are provided in a controlled panel and are preferably made automatically operative. Detailed Description of the Invention: The following details were studied and achieved in realizing the objects of the invention. Addition of oil-water emulsion to moist coal charge not only increased the bulk density of coal but also improved the handling and the flow properties of the coal charge. This helped in producing coke of uniform and improved quality and resulted in higher throughput of the ovens. Spraying oil-water emulsion on coal blend improves the flow-ability of coal by reducing its angle of repose. A novel system for oil-water emulsion spraying over coal blend was also designed for the first time in the industry. The following improvements were observed: a. Different types of oils, like light tar oil, fuel oil, light diesel oil, de-phenolated oil, heavy diesel oil etc. had been experimented by spraying on coal charge to accrue the full benefits of oil- water emulsion addition on coal. b. From various experiments conducted, it has been observed that the highest densities of coal were achieved with least viscous oil. c. Increase in bulk density of coal charge as a result of oil-water emulsion addition was greatly influenced by the moisture content of the coal charge. d. A change in the moisture content brought change in the bulk density and also in the carbonization time. Experimental Verification: tn the preferred embodiment, heavy diesel oil and water emulsion was tried. Heavy diesel oil and water mixture in the ratio of 1.5 to 1.6 parts was sprayed on the coal blend. The oil addition to the coal blend was around 0.02-0.03% by weight of the charge coal. The system performed successfully during trials. The process parameters in designing the oil-water emulsion spraying system were based on the considerations mentioned in Table 1. Table 1: Process parameter considered in designing a most preferred oil-water emulsion spraying system: Brief Description of the Accompanying Drawings: The invention will now be more fully described with reference to the accompanying drawings wherein, Figure 1 exhibits the schematic arrangement of the oil-water emulsion spraying system. The system (1) consisted of a 9 m3 water tank (2) installed at ground level. The tapping of water has been taken from nearby main water supply line (3) (not shown) through a manually operated gate valve (4) (not shown). A mild steel fabricated oil storage tank (5) of 6 m3 was installed below the ground level with due care of fire safety norms. Oil from oil tanker (6) (not shown) was filled in the underground oil tank (5) by gravity flow. The outlet (7) of the water tank (2) and the out let (8) of the oil tank (5) were connected to a common mild steel fabricated mixing tank (9) of 1 m3 capacity. The mixing tank was installed inside a shed. Water was pumped into the mixing tank by means of a pump (10), preferably of 2.6 m3/hr capacity. The flow rate of water was controlled manually by means of a globe valve (11), installed in the return line (12). Suitable manually operated isolation valves (13) were installed on both sides of the water pump. Similarly, oil from oil storage tank (5) was pumped into the mixing tank (9) by means of a pump (14) of 1.4 m3/hr capacity. Oil flow rate was controlled manually by means of a globe valve (15) installed in the return line (12). Suitable strainers (16) were provided in both oil and water lines before the pumps, to filter foreign materials. Motors of both oil and emulsion pump selected were of flameproof quality in order to avoid any eventual fire hazards. All safety norms had been considered in designing the system. The flow rates of oil, water and emulsion were measured by rotameters (17) installed in the respective lines. The oil and water were mixed in the mixing tank by counter flow principle. The mixing was further intensified by a re-circulation pump (18). The mixing tank was provided with three level sensors (19a, 19b, 19c) for low, intermediate and high level. The low level sensor indicated the initial quantity of oil filled in the mixing tank. After reaching this level, the oil pump was switched off. The water pump was switched on and the tank was filled with water pumped by water pump from the water tank. The water pump was then switched off when the level reached the high limit. After reaching the high limit, the re-circulation pump (18) was started and the uniform mixture of oil-water was formed. Once the level of emulsion reached the high level in the mixing tank, the sensor gave audio and visual signals in the control room. The high level signal indicated that the system was ready for operation. Subsequently, the operator could switch-on the emulsion pump (19) to supply the emulsion mixture from the mixing tank to the spray points over the feed coal. The capacity of emulsion pump was preferably designed as 4 m3/hr. The operation of the system was started with the switching on the button in the control panel. When the level of emulsion reached intermediate level sensor, the water and oil pumps were started simultaneously to feed the mixing tank at predetermined/set rates. Four different locations A, B, C and D were selected where oil-water emulsion was sprayed over the coal charge. These were the transfer chutes from conveyor belts to primary crusher and the transfer chutes from secondary crusher to a pneumatic classifier The supply of emulsion to the spray points was carried out through suitably designed pipe lines and spray nozzles A1, B1, C1 and D1. The flow rate of oil-water emulsion was controlled by a manual globe valve 20a, 20b, 20c and 20d installed in the line. There was also a provision to control the flow rate of emulsion at individual spray points by means of globe valves installed in the lines. Trials were conducted with different proportions of oil and water mixtures in the emulsions. The proportion of oil and water was varied in the mixtures to observe the effects on the operational parameters. High speed diesel oil and water were varied in the ratio of 1:5 to 1:6 in the emulsion mixture, so that the oil addition to the coal blend was around 0.02 to 0.03% of the coal charge. The comparative performance observed in the experiments carried on the existing coke ovens in a steel plant during the monsoon periods of 1999-2000 (before introduction of oil-water emulsion spray system) and 2000-2001 (after the introduction of oil-water emulsion spray system) are shown below in Table 2. Table 2: Comparison of coal/coke quality parameter before and after installation of oil- water emulsion spraying system in an experimental verification. Techno-Economic Benefits: • Oil addition has resulted in improved performance of selective crushing unit at the experiment carried out in an existing Steel Plant. • Coke quality (M 10) has improved to average 7.9 during July, August and September, 2000 compared to 9.0 during same period before installation of the system. • There is no deterioration in crushing level of coal blend during monsoon periods. • The crushing index (-3.2 mm) in July, August and September, 2000 were improved to 85.8%, 86.7%, 86% as against 82.5%, 83.8% and 85.74% during July, August and September, 1999 respectively. • Flow ability of coal has improved resulting in less jamming of chutes in coal handling plant. • There was no by-passing of classifiers during monsoon period compared to approx. 33 shifts by-passing during the same period before installation of the system. • There was no pushing droppage due to coal flow problems during the monsoon period compared to approximately 100 pushing droppage during the same period before installation of the system. We claim : 1. A method for controlled preparation of coal blend feed for coke oven such as to avoid problems of chute jamming and the like comprising: controlled feeding of an initial quantity of oil in a mixing tank by measuring and controlling the flow rate and by passing through strainers to remove any foreign particles; feeding an initial quality of water in the mixing tank depending upon the water content by measuring and controlling the flow rate and by passing through strainers to remove any foreign particles; pre-mixing the oil and water emulsion thus obtained in said mixing tank by counter-flow principle; subjecting the pre-mixed water and oil emulsion to intense mixing by means of a recirculation pump; operating an emulsion pump to supply the emulsion mixture to from said mixing tank to the spray points over the coal blend feed . 2. A method as claimed in claim 1, wherein, the water tank is preferably at ground level such that feed water is tapped from a main water supply line and it is controlled through a manually operated gate valve. 3. A method as claimed in claims 1 and 2, wherein, the oil storage tank is below the ground level preferably for fire safety norms and oil is fed into the underground oil tank by gravity flow from as supply tanker. 4. A method as claimed in claims 1 to 3, wherein, the flow rate of water into the mixing tank is operatively controlled by a globe valve and the rate of water is preferably controlled by having the globe valve in a return line. 5. A method as claimed in claims 1 to 4, wherein, the flow rate of oil into the mixing tank is operatively controlled by a globe valve and the rate of oil is preferably controlled by having the globe valve in a return line. 6. A method as claimed in claims 1 to 5, wherein, the oil and water are initially mixed in the mixing tank by counter flow principle and the mixing is intensified by re-circulation. 7. A method as claimed in claims 1 to 6, wherein, preferably, the initial quantity of oil is filled in the mixing tank to the required level indicated by a low level sensor, where after the oil feed is stopped and the water feed is started until the level reaches a pre-determined height, where after the feed of water is stopped. 8. A method as claimed in claim 7, wherein, a re-circulation of the initially formed water-oil emulsion is effected as long as necessary to obtain the uniform mixture of oil-water as emulsion. 9. A method as claimed in claims 7 and 8, wherein, the final emulsion is withdrawn from the mixing tank and fed to spray nozzles for spraying the emulsion on necessary beds of coal charge. 10. A method as claimed in claims 1 to 9, wherein, in a preferred embodiment, the continuity of emulsion formation and spraying on the coal charge is maintained by feeding water and oil simultaneously into the mixing tank once the level of the emulsion being withdrawn reaches a pre- determined level in the tank. 11. A method as claimed in claim 10, wherein, in a most preferred embodiment of the invention, the emulsion is sprayed on the coal charge being fed to one or more primary crushers and also on the coal charge from one or more secondary crushers to the respective pneumatic classifiers. 12. A system for controlled preparation of coal blend feed for coke oven such as to avoid problems of chute jamming and the like comprising: pump and motor means operatively connected to an oil storage for controlled feeding of an initial quantity of oil into a mixing tank including means for measuring and controlling the flow rate and strainers to remove any foreign particles; pump and motor means operatively connected to a water storage unit for controlled feeding an initial quality of water in the mixing tank depending upon the oil content including means for measuring and controlling the flow rate and strainers to remove any foreign particles; means for pre-mixing the oil and water emulsion thus obtained in said mixing tank by counter-flow principle; a recirculation pump means for subjecting the pre-mixed water and oil emulsion to intense mixing; an emulsion pump adapted for controlled supply of the emulsion mixture to from said mixing tank to the spray points over the coal blend feed . 13. A system as claimed in claim 12, wherein, the pump with motor associated with water storage tank and the oil storage tank are respectively provided with necessary gate valves for removal during maintenance. 14. A system as claimed in claims 12 and 13, wherein, there is provided a strainer element immediately after the water storage tank and the oil storage tank in their respective water and oil withdrawal pipes for removing any foreign materials. 15. A system as claimed in claim 14, wherein, there is provided flow measuring means both in the water and in the oil feed pipe in the mixing tank and the said means is preferably a rotameter. 16. A system as claimed in claims 12 to 15, wherein, the re-circulation means in the mixing tank is a pipe means and is provided with pump and motor and necessary gate valve at the initial emulsion formation stage. 17. A system as claimed in claims 12 to 16, wherein, there is also provided a final emulsion re-circulation pipes means necessary pump and motor and a gate valve and a globe valve. 18. A system as claimed in claim 17, wherein, there is preferably provided a strainer means immediately after the mixing tank in the final emulsion withdrawal pipe means. 19. A system as claimed in claim 18, wherein, the emulsion withdrawal pipe means is provided with a rotameter at its leading end to measure the quantity of emulsion sent for spraying. 20. A system as claimed in claims 12 to 19, wherein, in this embodiment, there is provided one or more location/s for spraying the emulsion on the coal charge wherein the coal charge is the transfer chute from the conveyor belt to a coal crusher. 21. A system as claimed in claim 20, wherein, in a preferred embodiment, there are provided four different locations which are transfer chutes from the conveyor belts to the primary crusher and transfer chutes from the secondary crusher to the pneumatic classifier and there are provided two primary crushers and two pneumatic classifier. 22. A system as claimed in claims 12 to 21, wherein, the mixing tank is preferably provided with three level indicators, namely a low level sensor meant for indicating the initial quantity of oil filed in the mixing tank, a high level sensor meant for indicating the level of initial quantity of water and oil fed into the mixing tank and an intermediate level sensor for indicating the level of emulsion as it reaches that level at the time of withdrawal of emulsion from the mixing tank. 23. A system as claimed in claim 22, wherein, the three sets of level indicators are provided in a controlled panel and are preferably made automatically operative. 24. A method for the preparation and addition of oil-water emulsion on coal blend for coke oven substantially as herein described with reference to the example. 25. A system for preparing oil-water emulsion and for feeding the same on one or more coal charges substantially as herein described with reference to the accompanying drawings. The present invention relates to a method for controlled preparation of coal blend feed for coke oven such as to avoid problems of chute jamming due to excessive moisture content in feed coal and a system for addition of oil-water emulsion through multiple spray nozzles on coal blend for coke oven. The system involves controlled feeding of an initial quantity of oil in a mixing tank by measuring and controlling the flow rate and by passing through strainers to remove any foreign particles; and also feeding an initial quantity of water depending upon the water content by measuring and controlling the flow rate and passing through strainers to remove any foreign particles; pre-mixing of the oil and water emulsion thus obtained takes place in said mixing tank by counter-flow principle. A recirculation pump subjects the pre-mixed water and oil emulsion to intense mixing. An emulsion pump operatively supply the emulsion mixture from said mixing tank to the spray points over the coal blend feed.

Documents:

709-CAL-2001-(02-02-2012)-FORM-27.pdf

709-CAL-2001-CORRESPONDENCE 1.1.pdf

709-CAL-2001-CORRESPONDENCE.pdf

709-CAL-2001-FORM 27 1.1.pdf

709-CAL-2001-FORM 27.pdf

709-cal-2001-granted-abstract.pdf

709-cal-2001-granted-claims.pdf

709-cal-2001-granted-correspondence.pdf

709-cal-2001-granted-description (complete).pdf

709-cal-2001-granted-drawings.pdf

709-cal-2001-granted-form 1.pdf

709-cal-2001-granted-form 13.pdf

709-cal-2001-granted-form 18.pdf

709-cal-2001-granted-form 2.pdf

709-cal-2001-granted-form 3.pdf

709-cal-2001-granted-letter patent.pdf

709-cal-2001-granted-pa.pdf

709-cal-2001-granted-reply to examination report.pdf

709-cal-2001-granted-specification.pdf