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TANWAT POWER PLANT(case study)
Power station Manager
2.1 Establishment of Tanwat:
Tanganyika wattle company (Tanwat) derives its name from the wattle tree (acacia mearnsii) from which a form of tannin known as mimosa extract used in leather industry is processed.
The company was founded in 1949 by Commonwealth Development Corporation (CDC) by gradual establishment of over 15,000 hectors of sustainable forest . Only bark which makes up about 20% of the bulk is processed leaving behind the rest as waste.
2.2 Core business.
Tannin continued to be Tanwat’s major revenue source until late 1960’s when decline in demand for leather goods brought about by availability of cheaper synthetic alternatives resulted in initiatives to explore for new forest products for long term future prospects.
3.2 Description of major equipments
3.2.1 Boilers (2units) 3.2.3 Chipping Plant (1Unit)
Make: Titan towler, Made by Mechmar of Malaysia Make: Klockner, German
Type: Water tube Type : Drum chipper
Rated output::15 tonnes per hr each Model:KTH 300X650L-6WT
Operating pressure: 30 bars
Steam temperature : 330 deg c
3.2.2 Steam turbine 3.2.4 Generator
Make: Dresser Rand, USA Make : AVK , Germany
Type :Condensing Terry turbine Rated Cap: 3125 Kva
Capacity: 2500kw Rated Terminal V: 3300 v
Rotor : speed 5345 RPM Rated frequency : 50 Hertz
4.2.1 FUEL -De-barked wattle logs (acacia mearnsii), Eucalyptas logs and saw mill wastes are chipped into small size 25 X 25 mm and conveyed to silos for storage from which they are fed into boiler furnaces at a rate proportional to energy requirement at the material time.
4.2.2 STEAM- Raw water which is only used as make up is passed through a cat-ion exchange water softener and comes out as soft water. It is mixed with condensate before being pump to thermal deaerator and finally into the boilers. Steam coming out is superheated steam at a temperature between 300- 3300C. Part of the steam is directed to the prime mover, a condensing turbine for power generation and the rest is desuperheated for using in the bark processing plant and sawn timber dry kiln.
5.1 Preventive maintenance
Direct Indirect/condition monitoring
-Cleaning -temperature measurement
-Lubrication, -vibration tests
-Programmed -abnormal sound
5.2 Planned shut down maintenance
-Done once or twice a year mainly with the purpose of cleaning cooling and feed water systems or do major replacement on chipping plant/conveying system and turbo alternator lubricating system.
-The maintenance is usually carried out for a period of less than 12 hrs
-The customers are issued with a one week notice.
5.3 Annual legal inspection
6.2 Power distribution.
7.1 Pollution of environment with boiler grits.
Solution: installed a grit arrestor on the flue gas line.
7.2 Monitoring boiler operating parameters
1) Boiler water level-lost one boiler in 1996 due loss of water
Solution: Intensive training on boiler emergency shut down procedure.
2) Steam temperature control-due lack of attemperator to stabilize super heated steam temperature.
Solution:1) Training on how reduce steam temp. manually using
super heater drain valve.
2) An alarm was installed to give a warning once
temperature exceeds 330 deg cent.
7.3 Copping with earth faults and lightning
Soln. 1) Removal of all the trees close to and leaning towards power lines.
2) Staff trained to do a quick reset before the turbine slows down.
7.4 Breakdown of major equipments and lack of standby units.
-eg chipping plant, turbine, and alternator
Sonl. 1) Emphasis on preventive maintenance.
. 2) Maintaining adequate stocks of spare parts and material.
7.5 Lack of skilled labour
The expansion of primary and secondary education in Tanzania, growing industrial an mining sectors have created very high demand for technical personnel in the recent past.
Soln.1) Intensive in house training and promotions
2) Improved remuneration package
4. PLANT OPERATIONS
4.1 Organization Structure