In the food industry, there is typically a requirement for electric power, process steam as well as cooling capability. Based on actual requirements of a specific site, a study was performed to define two different Combined Heat and Power (CHP) options and to compare them over a one year period regarding the extent to which they satisfy the operator’s needs.
CHP is defined as the sequential generation of two different forms of usable energy from a single fuel source. It is mechanical energy and thermal energy. The mechanical energy may be used either to drive a generator to produce electricity, or to drive rotating equipment such as a compressor. Thermal energy can be used either directly for process applications or indirectly to produce steam, hot water (district heating), or chilled water for cooling purposes. Combined Heat and Power technologies are proven, reliable and cost-effective. MAN can offer different CHP concepts adapted to specific customer requirements.
This paper presents the results of a comparative study based on the typical requirements of the food industry. The CHP system has to cover the demand for power, saturated steam at two pressure levels, and cooling. Two different CHP options were studied and compared regarding technical and economic considerations.
The first system proposed is based on a MAN’s gas turbine (model: THM1304-10N) in the 10 MW class, a Waste Heat Recovery Unit for steam production and one Absorption Chiller (ammonia/water) for cooling process. A share of the steam produced is used for driving the chiller.
The second system includes a combined cycle with MAN’s new MGT6100 gas turbine in the 6 MW class. A Waste Heat Recovery Unit and a back pressure steam turbine with two extractions at two intermediate pressure levels are used. A part of the saturated steam at the outlet of the steam turbine drives the absorption chiller and the remainder is used for the third steam process.
For both options, a supplementary firing is also considered. A technical and economical comparison between the two solutions is provided in order to show the advantages and the disadvantages of each system with regard to the requirements of the specified application.