电站锅炉汽机数据表(参考版)英文

Plant will be designed suitable for entire range of ambient and other environmental conditions. The various parts / components / assemblies of equipment and systems will be of proven materials with well established physical and chemical properties appropriate to the service as intended. All equipment and systems installed will comply with latest statutes, regulations and safety codes, as applicable in the area.

The brief salient design details have been placed as Annexure 5 at the end of this section.

4.1 Operational Capabilities of the Units

Operating Capability

Loading Rates (MW/minute) From 0% to 30% Rated Output 1% of rated output per minute - Under cold start From 30% to 50% Rated Output 3% of rated output per minute - Under cold start From 50% Rated Output to 5% of rated output per minute 100% BMCR

Start-Up and Shutdown Time Warmth Condition Cold Warm Hot

Maximum number of Start-Ups Start Up Condition Hot Start-Ups per year Warm Start-Ups per year Cold Start-Ups per year No of Start-ups 4500 1000 200 4.2 Steam Generator & Accessories

The boilers will be pulverized fuel fired, assisted circulation type. The boiler is be designed for SH/RH outlet conditions of 541oC / 541oC and capable of meeting

Start-up Notice Time (minutes) 580 170 110 the guaranteed performance while supplying steam for sootblowing, auxiliary steam system and heating of heavy fuel oil and excess air of 20% and meeting all environmental conditions as specified elsewhere in this specification. The offered boiler BMCR capacity is 2060 t/h steam generation. Each of capacity able to operate a turbo-generator set of 600MW, complete with superheaters, reheaters, economizer, air preheaters, two forced draft fans, two induced draft fans, two primary air fans and seven (7) mills will be provided. One concrete chimneys will be for three boilers. Supporting steel structure, soot blowing units, platform, galleries and stair ways, and all boiler internal steam, vent and drains piping, blow down / drain vessels, valves, fittings, fuel gas ducts and air ducts, dampers, lagging and refractory, casing, foundation bolts, boiler elevator etc.…, all other parts and works necessary for reliable and efficient operation of the boiler plant, will be provided with full detailed specifications..

The design of the Boiler and all the auxiliaries takes into account the worst figures of the range of coal specified.

4.2.1 Basic Design Data

The steam generator (SG) would be designed for firing 100% coal and would be natural circulation drum type. The SG would be of two pass design, radiant, single reheat, balanced draft, outdoor type, rated to deliver 2060 t/ hr of superheated steam at 175 ata, 540 C when supplied with feed water at a temperature of 246 C at the economiser inlet. The reheat steam temperature would also be 540.C. The performance figures for boiler is indicated below .

Boiler Design Parameters

Design Parameter Steam flow rate at superheater outlet Steam pressure at superheater outlet Steam temperature at superheater outlet Steam flow rate of reheater outlet Steam temperature of reheater outlet Steam pressure of reheater outlet Steam temperature of reheater inlet Steam pressure of reheater inlet Temperature of feed water Flue gas temperature at APH outlet Boiler efficiency (Based on HHV) 4.2.2 Overall System Description

From the raw coal bunker the raw coal is put into coal mill by the weighing coal feeder to be translated into coal powder. The coal powder is sent to burner in boiler furnace by hot air supplied by primary air fan. The oxygen for burning is supplied by forced draft fan. The air supplied by primary air fan and forced draft fan are both heated by air pre-heater. After Combusting the boiler flue gas will pass through electrostatic precipitator and induced draft fans then enter the chimney and will be discharged to atmosphere. Please refer to design description of each system for detailed description of all system.

Unit TPH MPa Deg C TPH Deg C MPa Deg C MPa Deg C Deg C % 100% BMCR 2060 17.5 541 1725.78 541 3.916 335.10 4.106 281.2 135 100% TMCR 1879.17 17.34 541 1579.60 541 3.577 325.30 3.762 275.1 134 85.2 LDO/HFO is considered as start-up fuel and accordingly start-up oil firing system with 3x50% pumping unit with strainer unit, start-up oil burners with igniters and scanners have been considered for low load operation upto 30%. The boiler pressure parts will comprise of drum, water walls, super heaters, economizer, reheater and inter stage attemperation system.

Two nos. of Rotary regenerative Air Preheaters (trisector type) per steam generator will be provided with a set of Soot Blowers required at the hot end and cold end.

The draft system for the boiler will be suitable for producing balanced draft with sub atmospheric pressure conditions in the furnace. The system will comprise of 2x50% axial type FD fans, 2x50% radial type ID fans and 2x50% PA fans (Cold air) of axial type for each unit.

Boiler will be provided with Air flue gas system and air ductwork comprises of duct, dampers, and expansion joints supports etc.

Provision for chemical dosing and blow down tanks have been envisaged for boiler to maintain the drum water and main steam chemistry.

4.2.3 Pulverised Coal System

Boiler adopts direct-fired tangential system with intermediate speed mill. There are 7 mills altogether, 5 ones operating at BMCR, and another two are standby for design coal.For the worst coal ,there are 6 mills operating and 1 mill standby at BMCR..These will be of sufficient capacity to attain the MCR of the steam generator when boiler firing the design coal and the worst coal with any one mill out of service. In other words, the total number of mills with its associated feeders will be such that when firing the specified worst coal, six mills will be in operation and one will be standby. When firing the specified performance coal, five mills will be in operation and two mills out of service.

Because of the positive pressure in the mill and coal feeder, two sealing air fan are furnished to supply the sealing air to avoid the powder leaking.

Each boiler will be furnished with seven sets of raw coal bunker, five of them has enough capability(design coal) to supply one boiler firing coal not less than 8 hours at BMCR condition.

4.2.4 Arrangement & Technical Details

The boiler will be of a drum type subcritical controlled circulation unit with single reheat. It is outdoor-arranged and has a single furnace of reverse U-form and full pendant structure steel, dry bottom type water-cooled, balanced draft furnace and is designed to seven mills and tangential firing burner. Light fuel oil will be used for start-up.

Main superheater steam temperature will be controlled by spray water attemperation and reheater steam temperature will be controlled by nozzles tilt. All the designs will be in accordance with IBR（India Boiler Regulation）, ASME ―Boiler and Pressure Vessel Code‖ and ―National Fire Protection Association Code‖. Material of the main pressure parts will be selected according to ASTM or its equivalent standards. Furnace （primary）

Type Furnace Dimension

Water cooled membrane wall Hyper bottom type Width Depth Height (low water header to roof tube) Furnace Volume Radiant heating surface (Including division panels) 18542 mm 17448 mm 67000 mm 17852 m 9104 m2 3

Coal Combustion System Description Tilting tangential firing system

The tangential firing system is based on the concept of a single flame envelope, both the fuel and air streams for each corner of the furnace are aimed tangent to the circumference of a circle in the center of the furnace. The resulting flame pattern forms a large swirl in the furnace.

Fuel and air nozzles tilt in unison to raise or lower the flame in the furnace to control furnace heat absorption and heat absorption in the superheater and reheater sections. Windbox assemblies

Windbox assembles are installed in each of the four corners. Each windbox will be divided into several compartments. The compartments are designed for pulverized coal container, mechanical atomized HFO burner are located in two-layer compartments. They are of class 2 category as defined in NFPA code 8502. The top compartments are used to admit overfire air (OFA). Air and fuel nozzle tilts

The air and fuel streams are vertically adjustable by means of the movable nozzle tips in each windbox compartment. The oil and auxiliary air compartment nozzle tips can be tilted upward or downward through a total angle of approximately 60 degrees (30 degrees up, 30 degrees down). The coal compartment nozzle tips can be tilted upward or downward through a total angle of 54 degree (27 degrees up, 27 degrees down) when operated in parallel mode. Wide range coal nozzle design

The wide range coal nozzle assembly is the advance design for improving ignition stability throughout a greater load range and can be made to achieve a low load operation while maintaining a stable coal flame without the use of support fuels on tangential fired boiler. This unique design works by inducing both turbulence and recirculation to the discharging coal/air mixture. As a result, the coal particles ignite and stability local to the coal nozzle tip discharge.

Each assembly consists of a coal nozzle and the nozzle tip similar in appearance to the standard coal nozzle/nozzle tip design. The wide range coal nozzles contain an internal horizontal spliter plate which separaters the coal/air mixture into fuel-rich and lean streams. This measures that the proper air to fuel ratios required for combustion are available over a greater range of pulverizer operation.

The wide range coal nozzle tips differ from the standard design by incorporating an irregular ―V—‖ shaped bluff body diffuser. The diffuser produces a lower pressure zone which induces turbulence and causes a high recirculation pattern to form. The trailing edge of the bluff body is equipped with a raised surface which shears the coal/air stream, furnace increasing the fuel eddy formation into a recirculation zone. It is these features which enhance the formation of the stable ignition point over a widerange of unit load. Low NOx coal burners

There are two methods for controlling NOx emission in the coal burners. One of them, as described above, the overfire air (OFA) is the remaining auxiliary air that is introduced to the furnace through OFA ports located at the top of the windbox. Another is the offset concentric firing system (CFS). Both OFA and CFS can be referred to as ―staging‖ techniques. OFA is a type of ―vertical staging‖ for controlling emissions, while CFS can be thought of as a ―horizontal staging‖ technique-unique to tangential firing. The CFS and OFA retard the conversion of fuel bound nitrogen at different times during the combustion history of coal particle within the furnace, thereby the low NOx coal burners can control NOx emissions effectively. LDO gun

The LDO burners are the wide-range mechanical atomizing type, retractable mechanisms by air operated, will to provided to maintain 35 percent BMCR for blow-down and 15 percent for normal operating condition. The oil gun is a double barreled gun, the inner barrel supplies oil to the atomizer and the outer barrel conveys the fuel oil away from the atomizer.

The minimum turndown ratio is 4:1 without changing the size of the burner tips. The boiler load can controlled automatically while maintaining good combustion conditions.

When the atomizer is withdraw completely from the burner, the fuel oil is to be automatically shutoff. The safety shutoff valve is to be arranged so that it is not possible to remove the atomizer without first shutoff the fuel. A quick automatic closing valve, solenoid operated, is to be provided in the oil supply to each burner arranged to shutoff the supply of oil to the unit on flame failure, draft failure, low oil pressure or low drum water level, or any cause of master fuel trip. Water Circulation System

Circulation pumps plus internally rifled tubes will be used. As result of using this type of circulation, the mass flow rate and fluid flow in water wall tubes are decreased because of the effect of the internally rifled tubes, and meanwhile the circulation ratio falls from 4 to 2. Consequently this type of circulation is characterized by the smaller diameters of wall tubes, the less tube weight, the higher reliability of circulation, the lower investment and lower plant town power consumption. Using reasonable heat release rate

The boiler design ensures sufficient weight flow velocity in water wall tubes under various loading to prevent departure from nucleate boiling (DNB). A part of tubes with internal spirals are used. Using membrane type construction

The membrane type construction for water wall is employed to ensure air tightness of the furnace. The width of the fins fulfils the working conditions. During variable pressure operation, the water distribution and heating of the water wall tubes are uniform to ensure even steam production along the width of the furnace and even water level along the full length of the drum. Sufficient dynamic head is produced to prevent stagnation, reverse flow, unstable hydrodynamic values etc. due to abnormal water circulation. The design of the furnace employs balanced draft, and provides adequate sustaining capability of explosion and implosion. The boiler has an expansion center to permit free expansion of boiler parts. The thermal expansion of water walls and main headers of other heating surfaces is indicated by three dimensional indicators.

The boiler roof employs gas-tight, all welded metallic construction, ensuring the free expansion of various heating surfaces without cracking and leaking under variable pressure operation.

The junctions of water wall and ash slag hopper employ qualified sealing construction, ensuring the free expansion of water walls. In the sealing water through effective washing equipment is provided to prevent ash accumulation that affects expansion.

Doors and holes are installed to facilitate the operators inspection and the access of maintenance personnel, and be able to withstand the thermal radiation without deformation. During operation, these accesses are shut tight and opening should be avoided. The clearance at the throat of ash hopper is 1400mm. The hopper slope is 55 degrees, the water wall tubes near the hopper and its supporting structure can withstand the impingement of large clinker and sustain the dead weight of an accumulation of clinkers up to the lowest level of burners during abnormal conditions.

The boiler employs suspended type construction. The steam/water pipes, flue gas ducts and steel structure connected with the boiler proper ensure the free thermal expansion of boiler water walls and the rear flue gas shaft. Drum and Its Internals Drum

Design Pressure Number of Supply Inside Diameter Overall Length Material 19.95 One (one) 1778 28854 mm DIWI353 mm Mpa Water Separating System Turbo Separator, Corrugate Dryer And Drying screen 112 pcs

The drum will be of fusion welded construction fabricated form carbon steel plate, and equipped with two suitable diameter manholes. The inside surface of the drum will be shop shotblasted leaving smooth, clean surface. When the boiler is operated within the visible range of drum gauge glass, standard steam quality and reliable water circulation is ensured. Drum Internals

Necessary internals for limiting the solid carryover in the steam leaving the drum to that specified herein. Drum Connections

The necessary welding end inlet and outlet connections and nozzles to accommodated the required valves and accessories provided for connecting up piping for acid cleaning reverse flushing of superheater, nitrogen conservation during boiler shutting down, hydrostatic test ,chemical injection, continuous blowdown, sampling of steam and water, emergency drain, safety valves and vent valves and auxiliary steam. Drum Supports

The necessary drum supports will be furnished on both sides of the drum, ample space provided for maintenance persons.

The design and manufacture of the drum conforms to ASME boiler and pressure vessel code. Water Quality

CONSTITUENT PH Value Colour Temperature Total Suspended Solids (mg/1) Total dissolved solids (mg/1) Oil & Grease(mg/1) Potassium (K) Chlorides as C1(mg/1) Calcium (Ca++) VALUE 6.5 – 7.8 Colourless 32°C Less then 100 80 Less then 2 Less then 3 11-17 About 19 Sulphate as SO4 Sodium as Na (mg/1) Zinc as Zn (mg/1) Iron as Fe (mg/1) Bicarbonate as HCO3(mg/1) Silica, ppm Total Methyloranye Alkalinity experienced as CaCo3 Dissolved CO2 Dissolved O2 Turbidity (in Silica scale) 3 – 5 13 0 – 10 1.8 – 2.2 44 6 48 7.2 2.00 100ppm Oil System

The equipment will include following described LDO system. Fuel Oil is be received in road tankers and Contractor is provide all plant and machineries for oil unloading, storage, heating and feeding to boiler, for power plant requirement. The plant is be suitable for operation over the entire life and perform as specified with LDO having composition. The size and number of oil handling equipment is be based on oil as a supporting fuel. The complete piping, valves and fittings for the equipment described above will be supplied. Air preheater

Number of supply : Two (2) Type :

Regenerative Ljungstrom Trisector Airheater

The rate of air leakage on BMCR is less than 8% and after one year will be less than 10%.

Boiler Structural Steel Work Structure Steel of Boiler House

We will provide all structural steel required for the steam generator and all other equipment within the scope of this contract.

Permanent enclosures will be supplied to give protection against the weather for plant and personnel in areas where considered necessary e.g. drum, burner, galleries. Platforms, Walkways and Stairs

All walkways and stairs will be constructed and provided and will be supported entirely from frames and steelwork provided in this contract, checkered plating of 5mm thickness will provided in front of each burner. Two (2) sets of stairs and walkways are to be provided for the boiler on each side. They are to extend from the basement level to the highest part of the units. Walkways are also provided along the front and rear of the unit as necessary.

The seller will average his construction procedure so that the major part of these walkways and stairs are installed at the same time as the unit structure in order to provide safe access to the plan equipment during assembly.

Soot Blowing System

The boiler will be accompanied with a complete set of a programmable automatic sequential steam operated sootblowing equipment for cleaning the furnace waterwalls, superheaters, reheaters, economizer and air heater while boiler is on operation.

The sootblowing system will include as follows:

(a) Steam and drain piping system including valves, fitting, supports, steam pressure reducing valve and thermal drain valve.

(b) A microprocessor based type programmable controller with color CRT monitor and operator keyboard.

(c) Sootblower quantity - Wall sootblower 100, Long retractable sootblower 40 . AH sootblower 2

Soot Blower Specification Table

Number Location Wall sootblower 100 Water Wall Long retractable Soot blower 40 SH.RH.ECO AH sootblower 2 Regenerative air preheater Rotative Angle Travel Blowing Time Steam Consumption (per blower) Effective blowing radius Motor 0.18 KW 1.1 KW 0.18 KW 1.5-2.0 m 1.5-2.5 m Approx. 2m 360 deg 267 mm Approx. 3 min Approx. 650 kg/min 360 deg 9300 mm Approx. 4-6 min Approx. 40-80 kg/min / 6000 mm Approx. 23 min Approx. 70 kg/min

Temperature Probe

Retractable furnace temperature probe with approximate travel 8 meters complete with totally enclosed motor, limit switches, position transmitters and position indicator, remote control switches, local push-button station. Pressure Part material

Pressure part Low temperature super heater Inlet header Outlet header Panel Super heater Tubes component Tubes Material SA 210C, 15 Cr Mo G SA-106C SA-335P12 15 Cr Mo G, 12Cr 1Mo VG, SA-213TP 304H Inlet header Outlet header Platen Super heater Tubes SA-106C SA-335P12 12Cr 1Mo VG, SA 213 T91, SA-213TP 347H Inlet header Outlet header Finishing Super heater Tubes Inlet header Outlet header Wall Re-heater Tubes Inlet header Outlet header Platen Re-heater Tubes SA-335P12 SA-335P22 12Cr 1Mo VG, SA 213 T23 SA-335P22 SA-335P91 15 Cr Mo G SA-106B SA-106B 12 Cr 1 Mo V G, SA-213T 91, SA-213TP 304H Inlet header Outlet header Finishing Re-heater Economiser Water wall Tubes Inlet header Outlet header Tubes Inlet header Outlet header Tubes Inlet header Outlet header SA-106B - SA-213T 91, SA-213TP 304H - SA-335P22 SA 210A1 WB 36 WB 36 SA 210 A1 SA-106C SA-106B Pressure part Drum component Material SA 299 A Air & Flue gas System

Ducts will be properly reinforced and be of welded construction for gas and air tightness. Suitable supports, expansion joints and access doors with bolted and hinged covers will be provided in all ducts where required. Hangers for ducts and connections to the supporting steel for ducts and hoppers will be included.

Ducts will have bolted connections to equipment, expansion joints and access door frames. While designing hangers/supports adequate dust load will be considered. Required ladder/staging for maintenance work inside will also be included.

Design will ensure uniform distribution to various sections and prevention of accumulation at any point. Turning vanes, splitter plates etc., will be used, if required to streamline the flow.

Sections of duct requiring disassembly for regular maintenance of any part of steam generator will be sized conveniently. Bolted joints wherever used will be made leakproof using suitable gaskets and sealing compounds. Cross-connections with sufficient number of power operated dampers will be provided such that, to the limits of their capacity, the boiler may continue to operate safely following the loss of any one F.D. fan, I.D. fan or air heater (if applicable).

All dampers will be provided with suitable control linkage and so arranged as to facilitate local manual operation from a gallery or floor level. The main isolating dampers will be fitted with a locking device in the fully open and shut positions. Necessary platforms/stair-case, if required for manual operation of the damper, will also be provided.

Duct work will be insulated and the duct design will include adequate fixing cleats for the purpose.

Gas and air ducts will be designed for wind loads as specified and dead weight including weight of insulation and lining. Proper drainage of ducts will be ensured by pitching and lagging.

The flues, ducts and windbox will be designed to be capable of withstanding a transient internal pressure of not less than 900 millimeters water, with stresses not exceeding minimum yield.

The measurement of air flows to the firing equipment will be taken as follows:

i) Primary air flow to the pulverizers will be measured using venturis, or electronic mass gas flow grids, located in the individual pulverizer inlet ducts.

ii) Combustion air will be measured using pressure taps or an electronic mass gas flow grid, located on the forced draft fan inlet elbow.

In designing the flue gas system, the proper gas velocity, gas distribution in the ductwork, minimizing draft loss, and minimizing dust deposition on the floors of the breeching and on the surfaces of corrective devices such as turning vanes, distribution plates, expansion joints, etc. will be considered The use of internal stiffeners, bracings, etc., exposed to the gas path will be minimized to limit their erosion. In cases where such components must be utilized, protection against erosion (e.g. shielding) will be provided.

Air ducts and windbox ducts with a cross-sectional area of 0.186M2 (2 ft²) and less will be fabricated of not thinner than 3 millimeters (1/8 inch) steel plate, and those with a cross-sectional area of more than 0.186m2 (2 ft²) will be fabricated of not thinner 5 millimeters (3/16 inch) steel plate. Air ducts and windbox ducts will be reinforced with steel angles and straps having a minimum thickness of 6 millimeters (1/4 inch).

Gas ducts will be constructed of steel not less than 6 millimeters thick. Gas ducts will be furnished with supports to carry weight of duct, insulation, dust 600 millimeters (24 inches) deep on the bottom, and vertical live load on horizontal projection of roof surface of 0.02 bar (40 lbs per sq ft). Gas ducts will be reinforced with steel angles and straps having a minimum thickness of 6.35 millimeters (1/4 inch). Ducts will also be designed for the wind loads specified in General Technical specification (Vol-IIA). Access doors will be fabricated of steel plate with a positive closing mechanism, and will be gas and airtight. The minimum size opening will not be less than 375 millimeters (15 inches) on vertical and 525 millimeters (21 inches) on the horizontal axis. Steel plate bolted over any of the access openings is not acceptable.

The ducts and windbox will be welded wherever practicable. Where not welded, the ducts and windbox will have bolts not less than 8 millimeters (5/16 inch) in diameter spaced not more than 75 millimeters (3 inches) apart, and joints will be seal-welded in the field.

Expansion joints in the ducts will be provided as required by the design to permit the free movement of the ducts without distortion and without inducing stresses at the air heaters or fans. Provisions will be made to prevent accumulation of fly ash in corrugations. The flexible elements for the flues will be stainless steel for gas temperatures above 538oC (1,000 F), Corten (or equal such as LACR steel) for temperatures of 427-538 oC (800-1,000 F), and carbon steel for temperatures below 427 oC (800 F). Where temperatures under all conditions permit, a non-metallic type may be used and will have pillows and shed plates. For air ducts, the expansion joint flexible element will be carbon steel.

Distribution plates and other corrective devices, such as teardrop vanes, will be incorporated as required on duct transition pieces.

Permanent scaffold brackets will be provided where scaffolds would be required for maintenance. Access platforms will be provided at all hopper outlets.

Spring hanger assemblies, where required, will be preset for the movement and loading anticipated. All hanger and tie rod assemblies will be adjustable.

Dampers will be of the balanced multiple leaf type. Dampers will be provided in separate, flanged duct sections with rigid shaft mounted leafs on bearings arranged so as to be protected from excessive temperatures. Bearing lubrication will be capable of being accomplished from permanent access platforms, which will be provided. Dampers will operate freely in all positions and will make tight seals when closed. Each damper will have an external position indicator. Manual operators for dampers will be provided with dust tight gear operators. Automatic controlled dampers will have a lever with a clamping device for manual operation. Dampers will be suitable for throttling to 10% of maximum rating.

Power operators will be provided for dampers with automatic controls and for dampers requiring non-modulating remote manual or automatic actuation. These will include dampers in the burner and igniter control system which require remote operation or setting during normal start-up, shut-down or post-emergency trip operation for the purpose of preventing fires or explosion due to retained fuel in the ducts, fuel pipes, furnace or steam generator passes.

When air cylinders are furnished for on-ff type dampers, they will be equipped with integrally mounted and piped/tubed solenoid valve actuators, and if required, an air filter/regulator with an indicating gauge assembly suitable for the services.

Position indication will be provided for all power operated dampers. Indication will include ―damper full open‖ and ―damper full closed‖ position indication.

When air cylinders are furnished for modulating type Dampers, they will be equipped with integrally mounted and piped/tubed Electropneumatic Actuators and Air filter Regulators with indicating gauge assembly suitable for the services. The assembly will contain also a Position Transmitter for remote monitoring of the Damper Position.

Acoustic insulation will be used on air and gas ducts to restrict the noise level to less than 85 dBA at a distance of 1.0 M.

5.4 Fuel Oil System

The Fuel Oil System will consist of Light Diesel Oil (LDO) System and Heavy Fuel Oil System (HFO).

The Fuel Oil Handling System will include the following system:

a)

Fuel Oil unloading and storage system meant for unloading of Heavy Fuel Oil (HFO) from rail tankers and Light Diesel Oil (LDO) from Road Tanker and Storage of the same to bulk storage tank. A bypass line for each pumping station is also provided in the event of road tankers having their own onboard unloading facilities.

Fuel oil pressurising system for both HFO and LDO and heating of HFO -meant for supply of oil at required atomising pressure and temperature from the storage tanks to the burners of the boiler; and return oil to the storage tanks. Fuel oil from bulk storage tank will be forwarded to the pressurising units.

b)

5.4.1 Major Design Criteria

Fuel Oil Unloading, Storage and transfer system

a)

Road Tankers will be positioned by the side of the unloading manifold and unloading pumps will be used for unloading of oil & storage of the same. Before unloading HFO, it will be heated by steam, in the tanker, to make it flow able, if necessary. HFO will be heated in the bulk storage tank and day storage tank to maintain a suitable temperature by supplying steam through floor coil heaters. Floor Coil heaters will be sized to raise the temperature of HFO from 20C to 50 C in 4 hours. Tanks will also be provided with suction heaters with steam as the heating source to heat the oil before sending it to heating and pressurising unit. No such heating is required for LDO. Two (2X100%) LDO unloading pump and two (2X100%) HFO unloading positive displacement, multiple screw type heavy duty fuel oil pump sets, will be provided.

Two (2) LDO Storage tank having a capacity of 500 cu.m and Two (2) HFO storage tank each having capacity 2000 cu.m, tanks will be designed in accordance with API-650.

Three nos (3) LDO pressurising pumps and three nos (3 HFO pressurising pumps each having 50% capacity for each unit. positive displacement, multiple screw type heavy duty fuel oil pump sets with flame proof motors and auxiliaries, relief valves, isolation valves and non-return valves and suction simplex

b)

c)

d)

e)

strainer for each pump. The pumps will transfer the oil from storage tank to furnace.

f)

Heating arrangement for oil heaters including arrangements for temperature control. Suction heaters will be capable of raising the temperature of HFO from 50 C to 60 C at rated capacity. Complete HFO piping valves, strainers, each unit heating units & pressurising pump skids from the outlet of the storage tanks upto the oil burners of each unit and return oil piping from burners to storage tanks will be electric traced.

g)

5.5 Compressed Air Facilities

The Plant will require compressed air as service air for cleaning, maintenance of the plant and equipment and for operation of certain ancillaries of the plant and tools. Besides, completely dry and oil free control air will be required for use in controls and instruments. Both these requirements will be met by Oil free water cooled rotary screw compressor and air receivers of adequate capacity will be provided.

Each air compressor will be driven by its own electric induction motor. Each compressor draws atmospheric air through highly effective suction filter and discharge into an independent air receiver, which in turn are interconnected. In the event of an emergency the service air could be drawn, through suitable valving arrangement, to the instrument air system but not in the other direction. Normally both the systems will operate independently. For producing totally moisture free dry instrument air, compressed air from the air receivers will pass through suitable silica gel air dryers and electric heaters (alternately heatless drier) and the moisture free dry air will then be distributed through a network of piping. Bidder will provide interconnection of Service air (SA) and Instrument air (IA) headers with a Non-return valve. Instrument air will be drawn from Service air header when IA pressure drops beyond a preset value. In such events SA supply to all its consumers need to be stooped automatically through a solenoid operated isolation valve.

Compressors will be cooled by DM water, which will be supplied from the closed cycle cooling water pump provided by BTG bidder. The BTG Bidder would provide one common supply and return line from its CCW system with isolation valves at the terminal point near the boiler.

All the compressors and air drying units will be housed within a compressed house. Necessary handling and maintenance facilities will be provided.

Three (3) oil free screw type service air compressors (Two working, one for each unit and one common stand by), each having a capacity of 40

NM3/min and a discharge pressure of 8.5 kg / cm2 (g) would be provided for meeting the plant instrument air requirements.

The air-drying plants of matching number and capacity will be provided and these will be capable of achieving a dew point of (-) 40 deg. C at atmospheric pressure. Individual air receiver will be provided near each air compressor and further unit air receivers will be provided near main plant of each unit.

Also three (4) oil free type instrument screw compressors (Three working, one for each unit and one common stand by), each having a capacity of 100% and a discharge pressure of 8.5 kg / cm2 (g) would be provided for meeting the plant service air requirements. The requirement of the compressed air for the fly ash conveying would be met through separate dedicated compressors.

Three nos Service Air Receivers and Three nos Instrument Air Receivers Instrument air (12 cum capacity each)

The compressed air system would include accessories such as moisture separators and air receivers. The discharge lines of all the compressors would be headered. Desiccant type air driers one for each instrument air compressor unit of matching capacity would be provided.