Title of Invention

A ROTARY REGENERATIVE GAS COOLER FOR HEAT RECOVERY IN CEMENT PLANT

Abstract

This invention relates to rotary regenerative gas cooler (RGC) integrated in cement plant for waste heat recovery. The said rotary regenerative gas cooler comprising a cellular rotor (01), a rotor housing (02) and heating elements (03), and rotor being composed of multiple sectors, preferably twelve, said rotor housing comprising of a pair of pedestals circular housing shell and support beams, restrained sector plates mounted at the top and bottom support beams, provided with sealing surface for radial seals and passage for air or gas flow, said heating elements being provided with multi layers, the said rotary gas cooler being supported by support bearing (05) at bottom and guide bearing (4) at top, the said rotary gas cooler being adapted with a drive mechanism (6) as herein defined, access doors (07), cleaning device (08) and lubricating oil circulating arrangement (09) The said RGC operates integretedly in cement plant as shown in Fig 1.

Full Text

BACKGROUND OF THE INVENTION: The present invention relates to Heat Recovery System for Cement Plant Application. The present invention particularly relates to Rotary Regenerative Gas Cooler integrated in cement plant for waste heat recovery. The Rotary Regenerative Gas Cooler (RGC) has various applications like its Utility and Industrial Boilers, Steel Plants, Fertilizer industry and Cement Plants. Most of the cement plants, in order to have effective air pollution control install Gas Conditioning Towers (GCT) to cool the flue gas coining out of the Rotary Kiln before its entry in to the Electrostatic Precipitator. However, in most of the cases, the Gas Conditioning Towers do not perform optionally resulting in poor control over the air pollution. Further, there is no waste heat recovery system available in the cement plant, instead the kiln exhaust gas is cooled by spraying water in the Gas Conditioning Towers. High capacity Pumps are used to supply the water to the Gas Conditioning Towers which lead to high power consumption. Rotary Gas Cooler can be used in place of GCT to extract the heat from the kiln gas and the extracted heat is transferred to the incoming cold air. The hot air coming out of the Rotary Gas cooler can be used for drying purpose as well as for combustion in the combustor. SUMMARY OF THE INVENTION: The cost of fuel in any industry is spiraluig due to considerable quantum of heat energy left unused in the flue gases. Recovery of the unused heat energy in the flue gasses economises the fuel cost. The Rotary Regenerative Gas Cooler according to the invention is ideally suited for this purpose. The advantages of Rotary Regenerative Gas Cooler (RGC) over other types of heat exchanges are • Its simple, sound and proven design • Ease o f in stallatio n and maintenance • Flexibility of application The basic rotary gas cooler regenerative principle is simple by itself. It consists of a cylindrical rotor packed with specially profiled heat transfer elements and a housing divided into two sections-one for air flow and the other for gas flow. The rotor rotates at 1 to 3 rpm. As the heat transfer surfaces pass through the counter flowing exhaust gas'and incoming air streams, heat is absorbed uniformly and released to the air. Unlike recuperative type Airpreheaters, heat need not pass through tube or plate walls. Instead, heat is simply absorbed by and released from the same surfaces as t he entire mass of heat transfer surface rotates. The direct method of heat transfer surfaces rotates. This direct method of heat transfer results in uniformly higher metal temperatures than in recuperative Airpreh eaters. RGC can be used in two applications given below: a) Replacement for gas conditioning tower, and b) For cooling the clinker cooler exhaust gases before/ after dust removal equipment. In cement plants, the rotary kiln exhaust gas is cooled in the Gas Conditioning Tower approximately from 350° C to 150° C by spraying water before sending the gases to dust collecting equipment. The water spray caused settlement of dust at the bottom of the GCT, which is removed by the screw conveyor provided for this purpose. The RGC can be used in place of GCT to cool the kiln exhaust gases. The Rotary Gas Cooler takes away the heat from kiln exhaust gasses and transfers it to the incoming cold air. The hot air coming out of the Gas Cooler can be used for any drying operation or in any combustor in the cement plant or heating the condensate of the boiler. This system requires a cooling air fan, ducting and structures. But, this saves enormous quantity of water Dumoinc Dower reauired for water sDrav and eliminates the screw conveyor dust removal system and associated problems. The RGC can be used to cool the hot dust laden gases to less than 140° C before / after sending the gases to filter house / ESP handling at temperatures less than 140° C with reduced volume. The reduced temperature allows the normal inexpensive Filter fabrics (Polyester). Also, filter house /ESP downsized for low flue gas volumes. The present invention is illustrated herein below with reference to accompanying drawings, wherein Figure 1 represents the heat recovery system plant and Figure 2 represents the perspective view of the rotary regenerative gas cooler in heat recovery system plant. Heat recovery system in cement plants as in Fig-1 consists of Rotary kiln (1), Preheaters (2), Kiln Gas Cooler (RGC) (3), Cold air Fans (4), Condensate Heaters (5) and stack (6) in kiln gas path and Clinker Cooler (7). Electrostatic Precipitator (8), Clinker Gas Cooler (RGC) (9), Cold air Fan (10), Condensate Heater (ii), ID Fan (12) and Stack (13) in clinker gas path. The exhaust gas coming from the Rotary Kiln (1) is passed through the preheaters (2) where it heat the incoming lime power and then to kiln Gas Cooler (RGC) (3). The Rotary Gas Cooler (3) takes away the heat from the kiln exhaust gases and transfers to the incoming cold air supplied by the cold air Fan (4). The hot air coming out of the Rotary Gas Cooler (3) is passed through the Condensate Heater (5) to heat the condensate from the boiler and then to atmosphere through stack (6). Similarly, the hot gas from Clinker cooler (7) is passed through the Electrostatic Precipitator (8) and then to Clinker Gas Cooler (RGC) (9). The Rotary Gas Cooler (9) takes away the heat from the hot gas and transfers it to the incoming cold air supplied by the Cold air Fan (10). The hot air coming out of the Gas Cooler (9) is passed through the Condensate Heater (11) to heat the condensate from the Condensate Heater (5) and then to atmosphere through stack (13). The cold gas from the RGC is passed through the ID Fan (12) and stack (13) to atmosphere. The hot air coming from coming from the RGC can also be used for any drying operation or in any combustor in the cement plant. This system requires a cooling air fan, ducting and structures. But, this saves enormous quantity of water, pumping power required for water spray and eliminates the screw conveyor dust removal system and associated problems occur while using the Gas Conditioning Tower (GCT). In this project, the heat recovered from the Kiln and Clinker cooler gasses are used for heating the condensate of Boiler. Total waste heat recovered in this 6.5 million Kcal/hr is utilized for heating the condensate resulting in a fuel saving of around 50 Tons of coal per day. DESCRIPTION OF ROTARY GAS COOLER (RGC): Each RGC as shown in flgure-2, shall consist of the following salient components / assemblies. 1. Cellular Rotor (01) 2. Rotor Housing and Sealing system (02) 3. Heating elements (03) 4. Guide Bearing (04) 5. Support Bearing (05) 6. Drive Mechanism including Auxiliary Drive (06) 7.Access Doors (07) 8.Cleaning Device (08) 7. Lubricating Oil Circulation system (09) 1. CELLAR ROTOR: The vertical rotor is made up of 12 sectors. The rotor consists of a central rotor post and cellular rotor shipped in shipped in separate pieces to be assembled at site for completeness of rotor. The baskets containing heating elements are to be installed in the completed rotor. The baskets containing heating elements are to be installed in the completed rotor at site. 2. ROTOR HOUSING AND SEALING SYSTEM: The housing is round in shape and consists of the following: Two main pedestals, circular housing shell and support beams called centre sections. The above assembly forms an integral structure to take axial and radial loads and also form a gas tight enclosure for the flow of fluids. Restrained sector plates mounted at the top and bottom support beams provide sealing surface for radial seals and passage for air and gas flows. 3. HEATING ELEMENTS: Each RGC is provided with multi-layers of heating elements with open profile to suit the dust laden hot gas. The cold end elements are basketed for easy removal and replacement from the sides. Hot end elements are removable from the top of the gas ducts. 4 GUIDE BEARING: The guide bearing is of spherical roller type and is located at the top centre section. The guide bearing has a water jacketed housing. The bearing housings are designed to act as oil reservoirs for provision of integral oil circulation system. 5. SUPPORT BEARING: The support bearine is of spherical roller thrust bearing type and is located at the bottom centre section. The bearing are designed to act as oil reservoirs for provision of integral oil circulation system. 6. DRIVE MECHANISM INCLUDING AUXILIARY DRIVE: The drive system envisaged is of peripheral pin rack-pinion type. It consists of a two input speed reducer with built in overrunning clutch, one electric motor for main drive, an air motor which is used as emergency drive, fluid coupling and a pinion for meshing with the pin rack of the rotor. Normally drive is through the electric motor and in the event of electrical trip-out, the air motor comes in to operation automatically, compressed air being admitted through solenoid valve. The air line is fitted with necessary filter with necessary filter lubricator. 7. ACCESS DOORS: Adequate number of access doors are provided, both at the inlet and ducts and also in the housing panels, for inspection and maintenance, 8. CLEANING DEVICE: The RGC is provided with a single nozzle swiveling arm type power driven cleaning device at gas in let / outlet side, for on-load cleaning of RGC elements. The cleaning device unit is iocated on the housing waii with the swiveling arm nozzle traversing horizontally in an area across the radius of the rotor, a short distance away from the elements packs. Medium used is compressed air. 9. LUBRICATING OIL CIRCULATION SYSTEM: Both the support and guide bearing are provided with oil circulation system. The oil circulation system consists of oil pimp, oil cooler, pressure and temperature indicators and flow switches. The lubricating oil system proposed is a proven design. The heat recovery system of the present invention is found to have the following advantages. 1. The Rotary Gas Cooler (RGC) regenerative principle is simple by itself, there by providing convenient heat recovery, as it consists of cylindrical rotor packed with specially profiled heat transfer elements and a housing divided into two sections-one for air flow and the other for gas flow. 2. The design consisting of Rotary Gas Cooler that rotates 1 to 3 rpm and the heat transfer surface pass through the counter flowing exhaust gas and incoming cold air streams, during that time it absorbs heat from the gas uniformly and released it to the incoming cold air. 3. The Rotary Gas Cooler id capable of being used in place of Gas Conditioning Tower (GCT) to cool the kiln exhaust gasses. The Rotary Gas Cooler does not require water spray, where as GCT requires enormous quantity of water to cool the kihi exhaust gasses. Because of water is directly mixed wife the kiln exhaust gas, the quantity of gas coming out of GCT is increased. To handle the increased gas quantity it requires larger size Fan and increased power consumption. If we use RGC in place of GCT, the Fan and Electrostatic Precipitator can be down sized to handle the low flue gas volume and thus less power consumption. 4. By using the above RGC in place of GCT, the hot air coming out of the RGC can be used for any drying operation or in any combustor in the cement plant or heating the condensate of the boiler and thus it saves fuel consumption. 5. By using the above RGC in place of GCT, Rotary Gas Cooler saves enormous quantity of water, pumping power required for water spray and eliminates the screw conveyor dust removal system and associated problems in cement plants. In the specification as narrated herein above though a specific embodiment has been illustrated with reference to the drawings, but many embodiments can be construed within the scope of the invention. WE CLAIM 1. A rotary regenerative gas cooler for heat recovery in cement plant characterized by a cellular rotor (1), a rotor housing (2) and heating elements (3), and rotor being composed of multiple sectors, preferably twelve, said rotor housing comprising of a pair of pedestals circular housing shell and support beams, restrained sector plates mounted at the top and bottom support beams, provided with sealing surface for radial seals and passage for air or gas flow, said heating elements being provided with multi layers, the said rotary gas cooler being supported by support bearings (5) at bottom and guide bearing (4) at top, the said rotary gas cooler being adapted with a drive mechanism (6) access doors (7), cleaning device (8) and lubricating oil circulating arrangement as herein described. 2. A rotary regenerative gas cooler as claimed in claim 1 or 2 wherein said cellular rotor has a central rotor post and a cellular rotor. 3. A rotary regenerative gas cooler as claimed in claim 1 or 2 wherein said rotor housing has support beams. 4. A rotary regenerative gas cooler as claimed in the preceding claims wherein said cooler is provided multi layers of heating elements. 5. A rotary gas cooler as claimed in any of the preceding claims wherein said lubricating oil circulating arrangement comprises an oil pump, an oil cooler, pressure and temperature indicators and flow switches. 6. A rotary gas cooler as claimed in any of the preceding claims wherein said drive mechanism is a peripheral pin rack-pinion type, consisting of two input speed reducers with built in over running clutch, an electric motor for the main drive and an air motor used as emergency drive fluid coupling and a pinion for meshing with pin rack of the rotor. 7. A rotary gas cooler as claimed in any of the preceding claims wherein said rotary gas cooler is provided with a single nozzle swiveling arm type power driven cleaning device at gas inlet/outlet side, for load cleaning of cooler elements with compressed air, said cleaning device unit located on the housing wall with swiveling arm nozzle. 8. A rotary regenerative gas cooler for heat recovery in cement plant substantially as herein described with reference to the drawings accompanying the complete specification.

Documents:

179-del-2003-abstract.pdf

179-del-2003-claims.pdf

179-del-2003-complete specification (granted).pdf

179-del-2003-correspondence-others.pdf

179-del-2003-correspondence-po.pdf

179-del-2003-description (complete).pdf

179-del-2003-drawings.pdf

179-del-2003-form-1.pdf

179-del-2003-form-19.pdf

179-del-2003-form-2.pdf

179-del-2003-form-3.pdf

179-del-2003-form-4.pdf

179-del-2003-form-5.pdf

179-del-2003-gpa.pdf

179-del-2003-pa.pdf

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