Title of Invention

AN IMPROVED MOTOR OPERATED RAW COAL ISOLATION DEVICE .

Abstract

The present invention relates to an improved motor operated raw coal isolation device adaptable to open and close the outlet of a raw coal storage bunker disposed below the bunker in a thermal power plant. The device comprising a fabricate corrosion resistance body (06) having at least two accesss ports with one molded gasket (07) and other one with rigid cover (08) and an end cover (09) for internal access to the body (06) equipped with molded gasket(10) assuring dust tight integrity and at least two hand wheels (11) provided integral with the body (06) and at least two corrosion resistance lined (13) isolators (12) and are supported by a plurality of suitable shaped racks (14) and a plurality of rollers (15)resting away from coal stream and each insulator is allowed to overlap the other at the centre of opening and a plurality of pinions (16) are provided on an operating shaft (17) such that a positive engagement is achieved between the insulators (12) via the rack (14) and a drive means (18) for driving the isolators(12), the drive means being actuated by an electric motor from the control room.

Full Text

FIELD OF INVENTION The present invention generally relates to the field of steam generation system. The present invention in particular relates to pulverizers, feeding raw coal to the boilers of steam generation system. More particularly, the present invention relates to a motor-operated raw coal isolation device to prevent flowing of ignited raw coal to the pulverizer from the storage bunker. BACKGROUND OF THE INVENTION Thermal power plants use Fossil fuels like coal to generate steam for Power generation. The fuel coal is delivered from coal mines to the power plant through rail, ship or by road transportation. The coal received at power plant is called raw coal. This raw coal is stored in storage yards. The raw coal cannot be fired directly in large capacity boilers / steam generators. The raw coal has to be pulverized so as to make it burn efficiently in a boiler furnace. In modern utility steam generating stations, the unit load is directly linked to the pulverizer. The pulverizer dynamically responds to the load. Hence, the pulverizer operation necessarily calls for a temporary storage arrangement. This storage arrangement is called as raw coal bin or raw coal bunker. The raw coal is susceptible to a risk of accidental ignition. If the coal is accidentally ignited, it will cause to develop a big fire hazard. With this fire in the bunker, if raw coal is admitted to pulverizer it will lead to catastrophic accident. To obviate this problem, it is desirable that an isolation device capable of preventing the flow of burning coal from raw coal bunker to the pulverizer, is provided. The raw coal bunkers are normally designed for storage capacity of ten to fifteen hours of boiler operation. As the raw coal is generally stored in a vertical column, any isolation device when provided needs to move against such vertical column of raw coal. In addition, monsoon brings more hardships by the way of increased moisture in the raw coal which results in coal column compaction. Due to such, the existing isolation devices available in market are suffering with the following setbacks. i) When the bunker isolation device is operated, arch formulation takes place which leads to mild to heavy choking of raw coal. ii) The isolation device cannot be closed to its full capacity (100%) since the entrapped coal between the isolation device plate (across the section) and the wall on the opposite end acts as a barrier. The opening size determines the flowabiiity of raw coal into the down stream. Bigger the opening, smoother will be the raw coal flow. During monsoon season, the flowabiiity of coal is very much affected due to increase in surface moisture. The arch formulation at the bunker outlet is common phenomena which almost interrupts the coal flow resulting starvation of coal into the pulverizer circuit. During boiler operation the raw coal flows in to the down stream, therefore during the normal condition, the isolation device can be easily closed as flowing raw coal does not pose severe problems in piercing through column of coal. However, when coal flow is interrupted due to reason beyond control, the closure of isolation device to its full capacity is impossible. Power station engineers resort a crude way of operation by manipulating the isolation device to move forward and backward and there by inching towards complete closure of the opening. Such a remedy is not reliable, safe and a technical solution. Isolation device is used to Open / Close at the bunker outlet by moving from one end to another. When the bunker outlet dimensions exceeds certain limit, the force required to shear the vertical coal column increases exponentially which may result halting the movement midway. Added to that, if the coal column is established, it may further aggravate the situation. OBJECTS OF THE INVENTION It is therefore an object of the invention to provide a motor-operated improved raw coal isolation device which eliminates the disadvantages of the prior art. Another object of the invention is to provide a motor-operated improved raw coal isolation device which ensures free and smooth flow of moistured raw coal even in monsoon periods. A further object of the invention is to provide a motor-operated improved raw coal isolation device which moves towards the center from the ends, and having its moving parts with smaller overlapping such that a full closer of the device is always ensured. Yet another object of the invention is to provide a motor-operated improved raw coal isolation device which does not require the coal column to be sheared in the direction of the opening, thereby allowing a complete closure of the device. A still further object of the invention is to provide a motor-operated improved raw coal isolation device which prevents flow of burning coal from the raw-coal bunker to the pulverizer thereby avoiding any catastrophic accident in a steam generation system. BRIEF DESCRIPTION OF THE INVENTION The motor-operated improved raw coal isolation device comprises: Corrosion resistant body: As the body of the device comes in contact with coal, it is made of corrosion resistant steel. The corrosion resistant steel body prevents rusting and withstands comparatively for a longer period. The body is made of sufficient thickness to withstand the corrosion. The isolation device is equipped with two access ports, each having a molded gasket under a rigid cover, providing a dust-tight closure. Covers are designed for easy removal. Inside surfaces of the covers flush with the body, to assure good coal flow. The body of the coal isolation device is a fabricated steel plate, with all joints in contact with the coal flow welded inside and out, and ground smooth to eliminate any edges on which coal could accumulate. The end cover, provided for isolation removal and interior access, is equipped with molded gasket, assuring dust-tight integrity of the isolation device. Two hand wheels are provided for manual operation. Indicators are provided for the wheel to indicate the 'open" and "close" directions. Corrosion resistant Isolator: There are atleast two isolators lined with corresion resistant steel, The isolators are supported by "L" shaped racks. The isolator is allowed to overlap each other at the center of the opening. The isolator by its design keeps the supporting rollers completely away from coal stream. The isolator edge is beveled so that the coal column is easily sheared. This design minimizes the potential corrosion from moisture in the coal, and contributed to reliable operation and long life. Rack and Pinion: To assure closure of the isolator without choking, pinions on the operating shaft engage "L" shaped racks which run down each side of the isolator. As the pinions are located above the racks, positive tooth engagement is ensured. Drive systems: There are two actuators to drive the two isolators. The actuators are synchronized to operate in tandem. The safe torque value is set on the actuator so that the actuator trips when the torque level exceeds. The actuators are operable remotely and locally. rack (14) which run down each side of the isolator. As the pinions are suitably located, positive tooth engagement is ensured. A Drive means (18): The drive means comprises a plurality of actuators (18) which drive the isolators (12). The actuators (18) are synchronized. Safe torque value is set on the actuator. The actuator (18) trips when the specific level exceeds. The actuators (18) are operable by an electric motor (not shown) from the control room or near to its fixation. WE CLAIM 1. An improved motor-operated raw coal isolation device adaptable to open or close the outlet of a raw coal storage bunker dispose of beneath the bunker in a thermal power plant, the device comprising - a fabricated corrosion resistance body (06) having at least two access ports with one molded gasket (07) and the other one with rigid cover (08) and an end cover (03) for internal access to the body (06) equipped with molded gasket (10) assuring dust-tight integrity; - at least two hand wheels (11) are provided on the body (06) integrated with actuator (18) for manual operation with an indicators to indicate open and close direction; - at least two corrosion resistance lined (13) isolators (12) and are supported by a plurality of suitable shaped racks (14) and a plurality of rollers (15) resting away from coal stream and each isolators is allowed to overlap the other at the centre of opening; - a plurality of pinions (16) are provided on an operating shaft (17) such that a positive engagement is achieved between the isolators (12) via the racks (14); and - a drive means (18) for driving the insulators (12), the device means being actuated by an electric motor from the control room. 2. The device as claimed in claim 1, wherein the rigid covers (08) and the end cover (09) each are respectively provided with molded gaskets (07,10). 3. The device as claimed in claim 1, wherein the isolators (12) are provided with corrosion resistant steel (13). 4. An improved motor operated raw coal isolation device adaptable to open or close the outlet of a raw coal storage bunker in a thermal power plant as substantially described herein with reference to the accompanying drawings. The present invention relates to an improved motor operated raw coal isolation device adaptable to open and close the outlet of a raw coal storage bunker disposed below the bunker in a thermal power plant. The device comprising a fabricate corrosion resistance body (06) having at least two accesss ports with one molded gasket (07) and other one with rigid cover (08) and an end cover (09) for internal access to the body (06) equipped with molded gasket(10) assuring dust tight integrity and at least two hand wheels (11) provided integral with the body (06) and at least two corrosion resistance lined (13) isolators (12) and are supported by a plurality of suitable shaped racks (14) and a plurality of rollers (15)resting away from coal stream and each insulator is allowed to overlap the other at the centre of opening and a plurality of pinions (16) are provided on an operating shaft (17) such that a positive engagement is achieved between the insulators (12) via the rack (14) and a drive means (18) for driving the isolators(12), the drive means being actuated by an electric motor from the control room.

Documents:

452-KOL-2005-FORM 27.pdf

452-KOL-2005-FORM-27.pdf

452-kol-2005-granted-abstract.pdf

452-kol-2005-granted-claims.pdf

452-kol-2005-granted-correspondence.pdf

452-kol-2005-granted-description (complete).pdf

452-kol-2005-granted-drawings.pdf

452-kol-2005-granted-examination report.pdf

452-kol-2005-granted-form 1.pdf

452-kol-2005-granted-form 18.pdf

452-kol-2005-granted-form 2.pdf

452-kol-2005-granted-form 3.pdf

452-kol-2005-granted-form 5.pdf

452-kol-2005-granted-gpa.pdf

452-kol-2005-granted-reply to examination report.pdf

452-kol-2005-granted-specification.pdf