Putting it all Together: Closing the Gaps
3.1 Identifying energy management opportunities (EMOs)
After some time, a picture starts to emerge about what can be done in a foundry to improve the way it handles energy use. A list of inputs may include the following:
- Results of the initial energy audit;
- Results of energy and material balances;
- Review of literature, including Internet sources;
- Information about applicable ideas from other foundries and other industries;
- Consultations with NRCan’s CANMET and Office of Energy Efficiency;
- Equipment supplier recommendations;
- Consultants’ advice; and
- A fresh look at the way the foundry manages its production and operations.
It all could result in a very long list of energy management opportunities (EMOs). The EMOs fall into these broad categories:
- Organizational changes – the changes in planning and scheduling production in a way that allow for a partial or across-the-board levelling of energy use, hence its better utilization;
- Process changes – improvements in process equipment and technological changes that result in reduced energy consumption;
- Energy efficiency of melting and fuel substitution – maximizing the efficiency of use and selecting the best source of energy (e.g., electrical power or natural gas);
- Electric power management – measures resulting in reduced electricity consumption, including power demand and power factor management, and cogeneration; and
- Heat recovery – re-use of waste heat streams and their integration and prevention of heat losses in all forms (e.g., heat exchanger, insulation).
The influence of the first category, organizational change, on energy conservation is often hidden. The point is to try to even out the timing, type and size of production orders to achieve a more steady-state production output. Granted, this may be a tall order, but one in which the marketing and sales departments can help production staff a lot.
The process change category will probably be the largest and most capital intensive. The improvements include changes to throughput capacity, improved quality (product characteristics) and process controls but, typically, efficiency of energy utilization has not been the driving reason. This can be used to justify other projects and upgrade activities (e.g., variable speed drives, high-efficiency motors).
The energy efficiency of melting and fuel substitution category concerns improvement upgrades to burner systems, monitoring and control of flue gas composition, and furnace lining and insulation. Fuel substitution is a consideration dependent on fuel market availability (e.g., natural gas in Quebec) and cost prognosis, and the type of metal cast. It can have a beneficial impact on both castings quality and cost (e.g., using electricity in melting aluminum).
Electrical power management can improve the profit of the foundry quite significantly by controlling power demand and power factor, and by comprehensive monitoring and control of electrical energy consumption in general (see Monitoring and Targeting methodology, see Section 2.1.8, “Managing energy as raw material,” page 30).
Heat recovery includes projects that are best viewed in the context of the entire foundry; several energy systems may be involved, and synergies are achievable.