Waste heat recovery with ORC

Waste heat and flue gas from industrial production can be recycled into electricity and heat - thereby replacing fossil fuel. The ORC process is an efficient, clean and reliable recovery method, that saves energy, costs and CO2.

Excess heat and flue gas from energy and industrial production are rarely utilized for the benefit of other than the birds, when leaving the chimney. However, it can be exploited for cogeneration of heat, electricity and even cooling in a technically uncomplicated and feasible way with the Organic Rankine Cycle (ORC) process. If the production of electricity and heat exceeds the plant's own consumption, the ORC unit can be coupled to the public power grid or nearby private companies or residential housing.

The ORC process is a proven and reliable recovery and cogeneration method. Excess and waste heat, in the form of either flue gas from various melting industries or from a combined cycle power plant, are used in a closed circuit, where a turbogenerator pre-heats an organic working fluid in a combined heat exchanger and evaporation system. As the temperature increases, the working fluid evaporates into a vapor, which power a low pressure turbine. The turbine drives a generator, which produces an amount of electricity typically corresponding to 19-20% of the total effect of the waste heat. The excess energy kan be utilized for heating and/or cooling, depending on the actual need.

A manufacturing plant can save up to 20% of its energy consumption through waste heat recovery

A fully automatic ORC unit offers a range of benefits compared to similar solutions:

  • High energy efficiency: 98% of the thermal energy is converted into electrical energy  (approx. 20%) and heat (approx. 78%)
  • Short pay back time of approx. 4-5 years. For larger units (1 MW electrical or above) the pay back period is considerably shorter
  • Simple start up plus operation and maintenance
  • Long life span plus low operational and maintenance costs.

Financial and environmental benefits

It is economically feasible to invest in a standard or customized ORC unit for recovery of flue gas and other types of waste heat. Standard units are available with production capacities from 0.5 to 3 MW. Depending on the type of industrial production and waste heat, the size of the ORC unit and the actual electricity price, up to 20% of the emitted heat can be recovered, thereby saving energy, CO2 and money.

There are substantial financial and environmental gains from installing an ORC based cogeneration unit in connection with very energy demanding industrial production such as cement and steel. In a typical cement plant recovery by use of an ORC unit of 0.5–1 MW electrical effect can replace a significant part of the plant's total electricity consumption. Steel production and other processing industries with various types of waste heat also offer considerable potential for recovery.

Good potential when decentral combined cycle power plants change from coal to bio mass 

From political hold there is an interest in encouraging power plants to use bio mass like wood chips, straw, wooden pellets, willow, animal manure or organic garden waste as an alternative to coal. When decentral combined cycle power plants are retrofitted to use bio fuel, it may be feasible to consider installing an ORC unit for recovery of the plant's flue gas. The ORC process is especially well suited for smaller, combined cycle power plants.

Thanks to Balslev's competencies within power supply and industrial automation, we offer consulting and design as well as turnkey delivery of ORC units for industrial companies and power plants.

Application areas

  • Cement industriy
  • Glass production
  • Steel production
  • Insulation production
  • Petrochemical plants
  • Refineries
  • Waste incineration plants
  • Decentral district heating plants using fossil fuel or bio mass
  • Combined cycle power plants

Balslev's services

  • Specificaiton of requirements
  • Feasibility studies
  • Conceptual design
  • Detail design and specification
  • Turnkey delivery
  • Commissioning

Peter Schiønning Smith

T +45 7217 7400

psm@remove-this.balslev.dk

 

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