A 'pinch' technology analysis of energy integration in the Huntly power station : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology

Abstract

Most processing industries use combinations of heat exchangers for heating and/or cooling process streams. A large amount of the energy used by the processing industries is used just for process heat. In the industrial nations of Western Europe approximately one third of the national energy use is for process heat (Smith, 1981). The design of most industrial processes is based on a long period of development with many evolutions and improvements leading to a current flowsheet. It is often assumed that these flowsheets are more or less optimal, with no significant "faults" left in them. This is of course not true. An analysis carried out by the New Zealand Dairy Research Institute (NZDRI) showed that theoretical minimum energy consumptions are 25 -30% lower than the actual energy consumption of the most efficient of New Zealand's dairy processing plants (Lovell-Smith and Baldwin,1988). For instance, the average energy use per tonne of casein powder produced in New Zealand is 16.9 GJ/tonne but the optimal energy usage is only 9.9 GJ/tonne. Recently, Linnhoff March Limited claimed that 2.5% energy saving in Huntly Power Station is possible but unproven. In terms of money this means about NZ$ 80 million of total saving over the station operating life( ≈ 30 years). [From Introduction]