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MHI and Tokyo Gas Develop New 1,000kW Gas Engine Cogeneration System
Featuring Higher Output and Efficiency and Lower Running Costs

Mitsubishi Heavy Industries, Ltd.
Tokyo Gas Co., Ltd.
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Tokyo, October 28, 2013 - Mitsubishi Heavy Industries, Ltd. (MHI) and Tokyo Gas Co., Ltd. have jointly developed a new 1,000kW gas engine cogeneration system. Both companies are scheduled to begin sales of the system on November 1, 2013.

The new system is developed based on the conventional 930kW gas engine cogeneration system, but the engine maintenance interval has been extended compared to the conventional system as the friction wear of the engine components is reduced by lowering the engine speed from 1,500 revolutions per minute (rpm) to 1,000 rpm, which ultimately results in reduction in engine maintenance frequency and cost. Also, the use of new long-stroke pistons has made it possible to increase generating output while reducing the engine's rated speed. Furthermore, the upgraded engine control technologies have contributed to achieve generating efficiency of 42.3% — the highest level in the 1,000kW class* — as well as overall efficiency of 78.5%.

Through these efforts for reducing maintenance cost and improving both generating and overall efficiency, the system running cost is considerably reduced. As a result, recovery of initial investment can be recovered approximately three years sooner than the conventional system. Moreover, the width of the enclosure has been reduced by 500 millimeters (mm) compared to the conventional system to serve more customers with various installation conditions.

In recent years, business continuity plans (BCP) and electric power conservation efforts have helped growing customer interest in energy-saving and environmentally friendly gas engine cogeneration systems. In response, MHI and Tokyo Gas have utilized their extensive experience in gas engine cogeneration development and adopted the unique concept of lowering engine speed while increasing output and efficiency to introduce this highly efficient new system to the market.

Working together, MHI and Tokyo Gas will continue to promote cogeneration systems for large-scale applications including urban redevelopment and industrial applications at mid-size factories to expand the business.

*Among gas cogeneration systems with an output up to 1,000kW sold by Japanese manufacturers as of October 1, 2013. (Source: Tokyo Gas Co., Ltd. market research; comparison based on lower heating values)

External view of the new 1,000kW gas engine cogeneration system

Configuration diagram of the new 1,000kW gas engine cogeneration system

Main features

1) Lower maintenance costs by lowered engine speed
 Engine speed has been reduced from 1,500 rpm to 1,000 rpm, resulting in reduced wear rate of components and extending the replacement interval for spark plugs and other consumables. Consequently, compared to the conventional system, the minimum oil change interval and other basic maintenance work have been extended to 1.5 times, and the minimum interval for top overhaul has been extended to 1.9 times, reducing overall maintenance costs by approximately 30%.

2) Higher output by lowered engine speed 
 Although lowering engine speed normally means lowered output, this new system is able to generate higher output as the engine's piston stroke is approximately 20% extended from the conventional system. In addition, the use of high efficiency turbocharger has increased the amount of compressed fuel-air mixture supplied into cylinders, which results in raising the mean effective pressure by 30% from than the conventional system. This enables the new system to deliver higher output (1,000kW, up from 930kW) with lower rated speed.

    [New long-stroke piston (conceptual drawing, inside engine cylinder)]

3) Increased generating efficiency and overall efficiency
 Improved engine control systems aids achieving generating efficiency of 42.3%, the highest level in the 1,000kW class. In addition, thermal efficiency has been improved by upgrading the one-stage intercooler used on the conventional system to a two-stage intercooler system to achieve overall efficiency of 78.5%.

    [Two-stage intercooler (conceptual diagram)]

4) Smaller dimension
 The overall width of the enclosure has been reduced by 15% (from 3,000mm to 2,500mm) to suit indoor installation such as hospitals and commercial facilities. Although high-output, high-efficiency systems generally require increased ventilation and capacity for auxiliary equipment, optimal arrangement of components within the new system ensures that space requirements are no greater than that of the conventional system.

Specification overview
Item Unit New System Conventional System
Engine model GS16R2 GS16R
Dimensions of enclosure
(width x height x depth)
mm 2,500 x 4,600 x 7,500 3,000 x 4,400 x 6,300
Generating output kW 1,000 930
Rated engine speed rpm 1,000 1,500
Generating efficiency % 42.3 40.0
Steam recovery efficiency % 17.3 14.8
Hot water recovery efficiency % 18.9 18.3
Overall efficiency % 78.5 73.2

Efficiency values assume the use of city gas 13A with a lower heating value (LHV) of 40.63MJ/Nm3 and tolerance of +5%.