Generating electricity and mechanical work

Electricity

Many plants generate their own electricity by directing part of the steam from a process-heat boiler to a turbine.

Recovering waste heat reduces steam consumption in the plant, making it possible to use a greater portion of the steam for generating electricity (provided there is more capacity in the turbines).
This can provide a very attractive way of reducing energy costs for plants with a high consumption of electricity.

Mechanical work

Some plants use turbines to drive compressors or pumps directly. Waste heat recovery will make it possible to generate more mechanical work as described above. 

10 MW of recovered heat can be used for generating electricity worth 1,100,000 EUR per year, assuming:

• The need for 10 bar(a) process steam is reduced and the excess steam is expanded to deep
  vacuum conditions, 0.05bar(a)
• 8,400 operating hours per year (350 days)
• 80% isentropic turbine efficiency (i.e. approx. 2.25 MW electricity generation)
• Electricity priced at 60 EUR/MWh  

Reducing the need for steam in the process means more steam can be used for electricity generation.