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Nishat's self generation power plant.

Nishat's Self Generation Power Plant

Nishat Mills is one of the oldest and largest textile mills in Faisalabad. The products of Nishat Mills ranges from spinning to finished products. A considerable part of the Mill activity is diverted towards the export. Non-availability of Power has been one of the problems seriously affecting the smooth operation of the Nishat Mills. This non-availability has become a permanent feature during the summer months, and in addition, sudden failures, and dips/fluctuations in voltage create problems of their own. The result of all these is loss of production.

As an interim relief Nishat Mills installed high speed diesel engines, unit capacity about 1000 kW, to provide power during emergencies and loadshedding. Due to the high demand of the Mills, a number of these sets had to be operated during loadshedding; this resulted in operational and maintenance problems. Long periods of loadshedding aggravated this problem even further. The use of diesel as a fuel also resulted in high operational cost. With this background Nishat Mills Management decided to seek out alternate possibilities.

Self Generation

In 1988 Jafri and Associates were invited to conduct a feasibility study of a base load self-generation unit to eliminate the problems related to power faced by the Mills. Initially a detailed survey of electrical loads of the Mills was made to assess the maximum demand. It was established that the Mills had a high load factor and the total demand was about 11 MW, including the immediate expansion plans. Various possible sites for the Powerhouse were also considered.

The power distribution system of the Mills was also studied in details. Currently WAPDA supplies power at 11 kV from two different grid stations. There are five load centres in the Mills. The feasibility established that the generation voltage of 11 kV would be most suitable; and the existing transformer rooms shall be the best location to provide the necessary hookup between the captive power plant and the various units of the Mills.

Boiler house and the steam system was also studied to consider possibility of cogeneration option. The study recommended that the maximum waste heat be recovered from the power generation plant to raise steam. The study considered various prime movers: diesel engines, steam turbines and the gas turbines. The conclusion was that diesel engine operating on heavy fuel oil was the best option. These engines are rugged and are of a proven technology. The unit size recommended by the study was 4 MW; four units were recommended, with one as a standby. The rate of return on investment was found to be about 20 per cent; the payback period of the loan was estimated to be five years. (incidentally this would now become more attractive because of the rise in electricity prices and reduction in the fuel prices).

Tender Document

Based on the findings of the Feasibility Study, a Tender Document was prepared by Jafri and Associates. Suppliers of established repute, long experience, and support in Pakistan were invited to participate in the Tender. The key feature of the Tender Document was its completeness; all technical and commercial aspects were covered in details. In the technical specifications, special emphasis was placed on items related to the furnace oil purification plant, supply of spares, proven record of the engine and generator, make of the auxiliary systems. Due to the scarcity and poor quality of water, air-cooled radiators were recommended for the cooling system. On receipt of the tenders a detailed evaluation report was prepared for Nishat Mills, and based on this report two technically best bidders were invited for the detailed discussions and negotiations.

After a tough competition, the work was awarded to a consortium of Krupp MaK (West Germany) and AEG (Pakistan); the engines and the auxiliary systems being supplied by Krupp MaK while the generator and the panels to be supplied by AEG. The overall responsibility of the work being with Krupp MaK. The nominal unit size of 6000 kW was also considered to be better option during the financial negotiations.

One of the key features of Krupp/AEG bid is the supply of local products for the control and distribution panels. This is being done for the first time in Pakistan. Large storage tanks and some other fabricated items shall be provided by a local company, M/s. Engineering Kinetics (Private) Limited of Lahore. The supervision of this work shall be carried out by Jafri and Associates and this would ensure quality of the product.

Technical Features

Some technical features of the Powerhouse, the engine, and the auxiliary units are briefly described below: Location: Due to the limitation of space at the Mills, the location of the power plant was one of the most critical aspects of the project. The feasibility had considered several sites and had recommended one which was optimal considering the load centres and ease of fuel movement. Despite the space limitation, the engine hall can accommodate four engines (additional space for the fourth engine has been placed for future expansion) and a service bay. The engine and generators shall be mounted on heavy foundations. The 5 ton overhead crane shall facilitate the maintenance.

The engine hall has been provided with ventilation facility and the design stipulates slight over-pressure in the hall to keep the hall free of dust. A tankfarm has been built on one side of the Powerhouse building. A containment wall around the tanks has been provided to contain the accidental spillage of oil.

Engine: The power plant is based on three 5880 kW units, one of the units shall be standby. The engines are four stroke, solid injection compression ignition type and operate on 600 rpm. The configuration is Vee with a total of 16 cylinders. The weight of each engine is about 52 tons dry.

Generator: Three synchronous generators shall generate about 6 MW power each and are connected in parallel. The generators are complete in all respects with necessary control and protections.

Fuel Oil System

The system has a capability of burning heavy fuel of viscosity 380 cSt, while the currently available fuel has a viscosity of about 180 cSt. Specifying a system which could meet more difficult fuel than what is available, ensures no difficulty in the future when the quality of available fuel is expected to deteriorate. Stored furnace oil shall be supplied to the settling tanks, therefrom it shall be supplied to the purifiers, which shall after purification, supply this oil to the day tanks. Two of the three purifiers shall be in operation at any one time. The purifiers have been fabricated by Westphalia of West Germany and shall be assembled at the site.

Lube Oil System

The system provides the lubricating oil to the engines. The system is complete with automatic back-flushing filters and self cleaning separators. Separate lube oil and refuse tanks have also been provided.

Radiator Cooling System

Due to scarcity and poor quality of water, the cooling system has been based on the air-cooled radiators. These radiators have separate sections for the cooling of jacket water, lubricating oil and the after-cooler. The radiators have been manufactured by AEG of Germany.

Waste Heat Boilers

Three waste heat boilers, one for each engine, has been provided to generate enough steam for the heating of the furnace oil tanks and pipelines. Some surplus steam shall be directed to the Mills for use as the process steam. With the waste heat recovery, the overall efficiency of the plant would be about 45 per cent, which results in an overall energy conservation.

Oil Storage

Two fairly large oil tanks, each 1800 cubic meter, have been provided for the storage of the furnace oil. This storage is considered enough for about six weeks supply. Two smaller diesel oil tanks each of 250 cubic meter have also been provided.

11 kV Switchgear

The 11 kV switchgear consists of three alternator panels, one transformer panel (for the Powerhouse use), five distribution panels and three generator neutral panels. These panels are connected to a single busbar. The busbar rated current is 1200 A.

Erection work

The erection work is being done by local workmen and only one expatriate supervisor shall be present at the site. This is indeed a credit to the local expertise. The mechanical and electrical work shall be supervised by Jafri and Associates. Ninety percent of the civil work has been completed. The electrical and mechanical work is expected to be completed by September this year.

Conclusion

The step taken by Nishat Mills is indeed pioneering and bold. It is expected that the project shall enable Nishat Mills to get rid of the unstable power supply position. This would mean higher production by the Mills. The self generation unit of Nishat Mills shall help solve the shortage of power in the area. The mill load shall ultimately be taken off from WAPDA and shall be available for other consumers. The precedent set by Nishat Mills would also encourage other large power consumers to set up similar plants and contribute towards self-reliance and higher productivity.

PHOTO : Oil bath filters placed on their foundations

PHOTO : Radiators in the process of erection on the steel frame

PHOTO : View of engine placed on wooden beams and steel sheet.
COPYRIGHT 1991 Economic and Industrial Publications
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1991 Gale, Cengage Learning. All rights reserved.

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Title Annotation:Nishat Mills, a textile mill
Publication:Economic Review
Date:Mar 1, 1991
Words:1537
Previous Article:World energy outlook.
Next Article:Karachi Electric Supply Corporation.
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