High pressure boiler

Subject-Power Plant Engineering,
Chapter 1- High-Pressure Boiler,
(Fluidized bed boiler, Indian Boiler Regulation Act)
By Prof. Kokare Amol Yashwant.

1. Chapter No. 2- High Pressure Boiler (Fluidized Bed Boiler, Indian Boiler Regulation Act 1920) Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y. Dnyan , Kala, Krida and Krishi Prathisthan’s

2. Unit No.2- High Pressure Boiler CO b- Select High Pressure Boiler for Power Generation capacity of Plants. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

3. A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exist the boiler for use in various Process or Heating applications or for Power generation. In Steam Power Plant, typically called Thermal Power Plant, water is heated to get steam for Power generation. What is Boiler? Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

4. A boiler is called a high-pressure boiler when it operates with a steam pressure above 80 bars. The modern high pressure boiler: Steam capacities – 30 to 650 tons/hour and above Pressure – up to 160 bar Maximum steam temperature – 540 ° C Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

5. Types of High Pressure Boiler La-Mont boiler Loeffler boiler Benson boiler Schmidt-Hartman boiler Velox boiler Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

6. Unique Feature of High Pressure Boiler Method of water circulation: Forced circulation , using pump Types of Turbine: Water Tube Boilers, with flow through several sets of parallel system of turbine – to reduce pressure loss occurring in single tube system and to have better control over quality of steam. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

7. - Improve method of heating: Saving of heat by evaporation of water above critical pressure of steam . Heating of water by mixing with superheated steam , to give high heat transfer coefficients. Increase in overall heat transfer coefficients by increasing water velocity inside the tube and increasing gas velocity above sonic velocity . - Compactness: Large number of small size tubes and number of pass are used which increases the heat transfer area, hence size and weight of boiler is reduced. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

8. Advantages of High Pressure Boiler over Conventional Boiler Due to forced circulation of water, evaporative capacity of boiler is increased and size of drum is reduced. Smaller diameter tube are used, which increases heat transfer rate and reduce fuel consumption. Pressurised combustion is used which increases the rate of firing of fuel thus increasing the rate of heat release. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

9. These boiler is compact and hence less floor space is required. Due to high velocity of water through tubes, the scale formation tendency is eliminated. Due to uniform heating of all parts, there is less chances of overheating . High pressure and temperature of steam lead to increase the plant efficiency. The steam can be raised quickly to meet the variable load. A very rapid start from cold is possible. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

10. La-Mont Boiler Types of boiler: Water tube , forced circulation , High Pressure boiler Steam Generating Capacity: 45 to 50 tones/hour Pressure : 120 atm. Temp.: 500 ° C Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

11. Principle: This boiler works on basic principle of forced circulation maintained by steam driven Centrifugal pump. If the water is circulate by a pump inside the tube, the heat transfer rate from gas to the water is increase . Various part of boiler: Economizer Centrifugal pump Evaporator tube Grate Furnace Super heater Water steam separator drum Air preheater Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

12. Working : A feed pump forces the water into the economizer where the temperature of water is increases. This water forced into the evaporator tube by using centrifugal pump driven by steam turbine. Water passes 10-15 times into the evaporator tube. The mixture of saturated steam and water is formed inside the tube. This mixture sends to the steam separator drum which is outside the boiler. Steam from the separator sends Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

13. to the economizer, where the saturated steam converts into superheated steam. The water again sends to the economizer where it again passes by the evaporator tubes. The air from the air preheater enter into the furnace where fuel burn. The fuel gases first heat the evaporator tube then passes by the super heater . These gases from the super heater again use to preheat the air into air preheater before exhaust into atmosphere. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

14. - Difficulties: The deposition of salt and sediments on the inner surfaces of the water tubes, which reduces the heat transfer rate . There also formation of bubbling at the inner surfaces of water tube. It leads to increase the heat flow resistance. - Advantages: High Pressure Boiler Flexible in design Easily start Higher heat transfer rate Reassemble in natural circulation Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

15. Benson Boiler Type of boiler: High Pressure, Forced circulation, Once through and Water tube boiler . Principle: This boiler works on the basic principle of critical pressure of water . Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

16. Advantages : The benson boiler does not use water- steam separator, which reduce the total cost of boiler. This boiler can transport easily from one station to another. It is economical and have higher efficiency . This boiler can use over the pressure above 350 bar without changing evaporator . This can be start easily and can reach its maximum load capacity within 10 minutes. - Disadvantages: Danger of overheating Salt deposition and sediment on the inner surface of water tube. inner surface of water tube. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

17. Loeffler Boiler Type of boiler: High Pressure, Forced circulation, Water tube boiler , Generating Capacity: 100 tones/hour Pressure: 140 bar Principle: This boiler working principle is to evaporate the feed water by the use of superheated steam from the super heater. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

18. Advantages: The evaporator tubes in this boiler carries superheated steam , therefore there is no salt deposition on the surface of tubes . Compact in design. High steam generating capacity. Suitable for marine application. Disadvantages : Bubbles are formed at inner surface of tube, which reduce the heat transfer rate. Evaporating drum is use, which increase the cost of boiler. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

19. Schmidt-Hartmann Boiler Pressure in primary circuit: 100 bar Pressure in secondary circuit: 60 bar In this boiler, working operation is similar to an electric transformer. Two pressures are used to effect an interchange of energy. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

20. - Advantages: Any deposits in evaporator drum due to impure water can simply brushed off by remove the submerged tube as of the drum or by blowing off water. As it can use impure water there is no necessity of water softening plant eventually reduces cost . It can utilize impure water for creation of steam. - Disadvantages: Evaporating drum is use which increase size of plant by cost. Due to deposits in evaporator drum because of impure water plant has to stop often for cleaning . Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

21. Velox Boiler Principle: When the velocity of the gas is greater than the speed of sound, its heat is transfer rate is also increase. So more heat is transfer from gas to water as compare when the heat transfer at the subsonic speed. Dnyan , Kala, Krida and Krishi Prathisthan’s Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

22. Advantages : This boiler has high heat transfer rate. It has great flexibility. It is compact in design . It is easy to control. It is fully a utomatic. It has thermal efficiency about 90-95 % Disadvantages: Need extra ground as of horizontal construction. Fuel oil burning power station lies in the high cost of fuel . It can only operate on liquid or gaseous f uels. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

23. Ramsin Boiler Principle: One through boiler. Forced circulation. Dnyan , Kala, Krida and Krishi Prathisthan’s Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

24. Advantages : This boiler has high heat transfer rate. It has great flexibility. It is compact in design . It is easy to control. It is fully a utomatic. Disadvantages: Fuel oil burning power station lies in the high cost of fuel . Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

25. FBC BOILER FLUDIZED BED COMBUSTION BOILER Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

26. INTRODUCTION  In 1921, the first fluidized bed being used successfully in Germany.  Fluidized bed combustion has emerged as a feasible alternative and has significant advantages over conventional firing system and offers multiple benefits – compact boiler design, fuel flexibility, higher combustion efficiency and reduced emission of noxious pollutants such as SOx and NOx .  The fuels burnt in these boilers include coal, washery rejects, rice husk, wood chips & other agricultural wastes.  The fluidized bed boilers have a wide capacity range0.5 T/ hr to over 100 T/hr. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

27. MECHANISM Fluidization of solids  Sand particles resting on a mesh (left) become fluidized when air is blown through (right) and take on the appearance and some of the properties of a boiling fluid.  Granular solids remain in layers when one is poured on to another (left), but rapid mixing occurs on fluidization (right).  A bed of stationary particles supports objects whatever their density (left). On fluidization, an object of lower density (the green ball) floats while the higher density (red ball) sinks.  In a bed of stationary particles (left), heat is transferred slowly and there are big differences in temperature. In a fluidised bed (right), rapid mixing ensures uniformity of temperature. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

28. CHARACTERISTICS OF FLUDIZED BED  Fluidization depends largely on the particle size and the air velocity.  Combustion process requires the three “T”s that is Time, Temperature and Turbulence. In FBC, turbulence is promoted by fluidization.  If sand particles in a fluidized state is heated to the ignition temperatures of coal, the coal will burn rapidly and bed attains a uniform temperature.  The fluidized bed combustion (FBC) takes place at about 840OC to 950OC. Since this temperature is much below the ash fusion temperature, melting of ash and associated problems are avoided.  The lower combustion temperature is achieved because of high coefficient of heat transfer due to rapid mixing in the fluidized bed.  Limestone is used as particle bed, control of sulphur dioxide and nitrogen oxide emissions in the combustion chamber . Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

29. Types of Fluidized Bed Combustion Boilers There are three basic types of fluidized bed combustion boilers: Atmospheric classic Fluidized Bed Combustion System (AFBC) Atmospheric circulating (fast) Fluidized Bed Combustion system(CFBC) Pressurized Fluidized Bed Combustion System (PFBC). Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

30. 1.AFBC / Bubbling Bed Coal is crushed to a size of 1 – 10 mm depending on the rank of coal. The atmospheric air, which acts as both the fluidization air and combustion air. The velocity of fluidizing air is ranges from 1.2 to 3.7 m /sec. Almost all AFBC/ bubbling bed boilers use in-bed evaporator for extracting the heat from the bed to maintain the bed temperature. The bed depth is 0.9 m to 1.5 m deep. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

31. FUEL FEEDING SYSTEM For feeding fuel, sorbents like limestone , usually two methods are followed: under bed pneumatic feeding and over-bed feeding. Under Bed Pneumatic Feeding If the fuel is coal, it is crushed to 1-6 mm size and pneumatically transported from feed hopper to the combustor through a feed pipe piercing the distributor. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

32. Over-Bed Feeding  The crushed coal, 6-10 mm size is conveyed from coal bunker to a spreader by a screw conveyor. The spreader distributes the coal over the surface of the bed uniformly.  This type of fuel feeding system accepts over size fuel also and eliminates transport lines, when compared to under-bed feeding system Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

33. 2 . Air Distributor  Purpose is to introduce the fluidizing air through the bed cross section, keeping the solid particles in constant motion.  The distributor, is constructed from metal plate having a number nozzles or nozzles with bubble caps .  The distributor plate is protected from high temperature of the furnace by: i) Refractory Lining ii) A Static Layer of the Bed Material iii) Water Cooled Tubes. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

34. 3. Bed & In-Bed Heat Transfer Surface: a ) Bed  The bed material can be sand, ash, crushed refractory or limestone, with an average size of about 1 mm. Depending on the bed height these are of two types: shallow bed and deep bed. b ) In-Bed Heat Transfer Surface  In a fluidized in-bed heat transfer process, it is necessary to transfer heat between the bed material and an immersed surface, which could be that of a tube bundle, or a coil. The heat exchanger orientation can be horizontal, vertical or inclined. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

35. 4. Ash Handling System Bottom ash removal  In the FBC boilers, the bottom ash constitutes roughly 30 - 40 % of the total ash, the rest being the fly ash.  Ash from the boiler furnace outlet falls into the crusher, where large ash particle is crushed to small size. Finally ash is carried by high velocity air to delivery point . Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

36. b) Fly ash removal The amount of fly ash to be handled in FBC boiler is relatively very high, when compared to conventional boilers. Fly ash carried away by the flue gas is removed in number of stages; firstly in convection section, then from the bottom of air preheater/economizer and finally a major portion is removed in dust collectors. The types of dust collectors used are cyclone, bag filters, electrostatic precipitators (ESP’s) . To diminish the SOx , recycling of fly ash is practiced in some of the units. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

37. 2. Circulating Fluidized Bed Combustion (CFBC) Taller boiler structure Coal is crushed to a size of 6 –12 mm depending on the rank of coal. The fluidizing velocity in circulating beds ranges from 3.7 to 9 m/sec. Combustion efficiency as high as 99.5%. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

38. 3.Pressurised Fluid Bed Combustion Combined cycle i.e Rankine & Brayton cycle using steam & gas turbine. Operating temp. & pressure is 860OC & 16-18 bars. The fuel is fed along with the sorbent and is maintained in fluidized condition in the pressurized combustion chamber. The pressurized flue gases are cleaned off & are expanded into a gas turbine. In addition, the excess air requirements of the boiler are met by the gas turbine compressor. Power generated by steam cycle and that generated by gas turbine which is of the order of 80:20 Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

39. Advantages of FBC boiler over Conventional boiler: High Efficiency. Combustion efficiency of over 95% Overall operating efficiency is 84% 2 . Fuel Flexibility. 3 . Ability to Burn Low Grade Fuel. 4.Pollution Control. SOx formation is minimised by addition of limestone for high sulphur coals. CaCO3 (solid) + SO2 (gas) → CaSO3 (solid) + CO2 (gas) SO3 + CaCO3 = CaSO3 + CO3 Low combustion temperature eliminates NOx formation. NOx formation takes place around1500o C 5 . Easier Ash Removal – No Clinker Formation 6 . Simple Operation, Quick Start-Up Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

40. 7. No Slagging in the Furnace-No Soot Blowing 8. Provisions of Automatic Coal and Ash Handling System 9. Provision of Automatic Ignition System 10.High Reliability and low maintenance costs. Disadvantages of FBC boiler over Conventional boiler: The only disadvantage is that, a large amount of power will be required to lift up the silica surface. So motor of force draft fan will b twice bigger than that of other conventional system . System required 50% more Dolomite and limestone. Erosion problem cause and Problem associate with distribution of coal and dolomite. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

41. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y. Sr. No Comparison Aspect Water Tube Boiler Fire Tube Boiler 1. Contents in tube Water Hot gases 2. Pressure of steam generated 165 bar (high) 24.5 bar (low) 3. Rate of steam generated High Low 4. Floor area Less More 5. Overall Efficiency 90 % (High) 75% (Low) 6. Direction of water circulation Well defined Not Definite dir 7. Operating cost High Less 8. Bursting chances Less More 9. Construction Complex Simple 10 . Application, Ex. Large power plant High press. boiler Small plant, Cochran, Lancashire

42. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y. Sr. No Comparison Aspect Conventional Boiler Once Through Boiler 1. Sub-critical or supercritical Both Sub-critical 2. Orientation of boiler tube Generally Vertical Generally Spiral 3. Efficiency at Part load High Poor 4. Circulation ratio One Four 5. Requirement of Circulation pump No even at high pressure Required for High Pressure 6. Uniform of water flow Uniform Not Uniform 7. Provision of blow down Not due to absence of drum Yes 8. Need of monitoring temp. temp. of tube monitor avoid overheating Not required due to mixture of water and steam at saturated condition 9. Start-up time Low High

43. INDIAN BOILER REGULATION ACT (IBR) Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

44. INDIAN BOILER REGULATION ACT (IBR) Regulations Act 1920". It is an Act of Law: "It governs the manufacture, installation, operation and maintenance of Steam Boilers ". To prevent hazards and explosions, some rules and regulations were introduced as mandatory to follow by industrial sectors . In India, IBR Act was established, which specified that, a Government Inspector would be responsible and would have to certify all steam boilers as 'suitable from the safety point of view. Every part of IBR approved steam system has to be manufactured, installed, tested, operated and maintained under the watchful eye of local inspector. Every customer, who runs an IBR boiler, must carry out an annual IBR inspection in Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

45. presence of an IBR The local BR office is a state government department and maintains satellite offices close to each inspector. In the IBR act, a steam boiler is defined as, "a vessel containing greater than 22.5 liters of water, which is IBR Boiler and IBR System. An IBR license is required to manufacture steam equipment This is a factory approval, even before, the company starts manufacturing valve or pipe etc. This license is also given to workshops, where adequate infrastructure for pressurized joint welding and testing is available. The product drawing is submitted for provisional IBR approval along with the necessary fees paid. Once the approval is received, raw materials have to be purchased from IBR approved vendors. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.

46. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y. The inspector has to be called to inspect and approve the material before manufacturing, Before commencing manufacture of a boiler or boiler component, every manufacturer shall engage an procedures as specified by IBR. Inspecting Authority for carrying out inspection at various stages of manufacture as per I.B.R. regulations. The Inspecting Authority shall follow necessary procedure for inspection and certification of boiler or If inspector finds the boiler or the boiler component conforming to the standards prescribed by boiler component. Regulations , he/she shall issue a 'certificate of approval' and stamp the boiler or boiler component. But, if inspector finds the boiler or boiler component not conforming to the standards prescribed by regulations, then 'certificate of

47. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y. refuse' has to be issued for non-conformance. Provided that, no certificate shall be refused unless the Inspecting Authority had informed the manufacturer to carry out necessary modifications or rectifications. But, if inspecting Authority finds that, inspite of giving necessary action. Conditions for Repairing Boiler and Boiler Component: No person shall repair any boiler or boiler component or both, unless he has necessary facilities for repairs , in the premises . Design &drawings of boiler or boiler components should be confirming to the 'IBR‘ regulations. The materials, mountings and fittings used in the repair of such IBR approved boiler or boiler component should conform to the regulations.

48. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y. 4. Person (engaged in welding) has a "Welder certificate" issued by a Competent Authority. Report of Accidents: Accident in "Boiler Act" is defined as, "an explosion of a boiler or steam pipe or any damage to a boiler or steam pipe" If any accident occurs due to a boiler or boiler component, the owner shall report the same in writing to the Inspector within twenty-four hours. Every such report shall contain a true description regarding nature of accident, damage to the boiler or to the boiler component or injury to any person. The report must specify all details, so that, inspector can judge the severity of the accident. Every person shall be bound to answer truly to the best of his knowledge and answer every question put to him in writing by the Inspector.

49. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y. Renewal of Certificate: The owner of any boiler, which is not registered under IBR, may submit application to the Inspector along with documents as prescribed by regulations to obtain certificate of registration. Every such application shall be accompanied by the prescribed fee paid. The Inspector shall fix a date (within thirty days or a specified period from the date of receipt), for the examination of boiler. certificate authorizing the use of a boiler is ceased after expiry of the granted period or when any accident occurs to the boiler, or when the boiler is to be shifted from one place to other.

50. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y. Penalties for Illegal Use of Boiler: Any owner of a boiler, who uses the boiler either without certificate of approval, shall be punishable with fine up to one lakh rupees, or in the case of a continuing offence, along with fine, additional one thousand rupees per day may be charged after the first day of conviction. authority may be punished. Also if any person, who has transferred boiler from one state to another without reporting to competent authority may punished. The owner is liable to punish, if he makes any structural changes, addition or renewal in IBR system without obtaining prior sanction of the Chief Inspector, or fails to report about an accident. Provisions under Boiler Act for Remedial Measure: Prohibitions of use of unregistered or uncertified boiler 2 . Renewal of certificate from time to time. 3 . Modification and Renewal to boiler . 4 . Modification or changes in steam pipes.

51. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y. Maintenance Procedure For Major Components Of High Pressure And Fbc Boilers • Maintenance of high pressure and FBC boilers can be done in two stages: ( A) Boiler inspection: The boilers are required to be tested regularly as per Indian Boilers Act. Before inspection, boiler should be made empty and all manhole doors, caps, mud drums, fire bars, front end bridge plates, oil burners etc. should be removed and boiler should be cleaned. All tubes, smoke boxes and external flues should be cleaned and checked. All the steam and water connections should be disconnected and then, it should be made ready for conducting the following tests : .

52. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y. (a) Hydraulic Test: This test is conducted to find out leakages in steam boiler. For this test, the mountings should be fitted tightly except the safety valves. The openings of the safety valves should be closed. All the joints should be made tight and leak-proof. Boiler should be filled with water and inspector's gauges should be fitted to the boiler. Generally, the boilers are tested at a pressure equal to twice the working pressure of the boiler. During this test, no part of boiler should deflect. ( b) Steam Test: This test is conducted to check whether the safety valves operate properly to relieve the steam, when the steam pressure inside the boiler exceeds the rated pressure. This operation is tested keeping the feed valve and steam stop valve closed.

53. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y. (B ) Boiler Maintenance: 1 . The combustion equipment should be so adjusted that, the temperature in the furnace does not follow: exceed the designed value. The air supply to the furnace should be in correct proportion. 2 . The water level in the boiler should not be allowed to fall beyond the minimum level. 3 . The temperature should change slowly and uniformly in the various parts of the boiler. Rapid changes in temperature lead to unequal expansion. 4 . The water used for steam generation should be free from scale forming impurities, because the scale deposited on tube and boiler shell does not allow the heat transfer to take place effectively and sometimes causes over heating of tubes and boiler shell, which may result in failure of tubes and boiler explosion.

54. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y. 5 . Soot and ash deposited in tubes on gas side should be removed regularly 6 . Bearings of pumps, stokers, pulverizes and fans etc., should be lubricated regularly. 7 . Oil or scale in the tubes is undesirable. Hence, such tubes should be traced or located to solve the problem. 8 . All stays should be in even tension and they should be properly adjusted. 9 . The tube leakage is caused due to extreme overheating of tubes as it is exposed to high temperature. The boiler should be stopped, when such leakage is noted and it must be immediately repaired.  

55. Babasaheb Phadtare Poly. (DME) Prof. Kokare A.Y.