Volume 26, number 1, March 2012

Powercast Manufacturing increases the competitiveness of its foundry by melting its energy bill!

Founded in 1978, Powercast Manufacturing Inc. operates a foundry that specializes in the production of molded aluminum castings. The foundry produces all kinds of parts: pumps, engine housings, pulleys, hubs, bases, drains, cover plates, frames, handles, boxes, and many more. The weight of these castings ranges from 50 g to 70 kg. Powercast serves customers in the electricity, telecommunications, transportation, lighting, and construction sectors, among others.

Until summer 2010, four reverberatory furnaces were used for smelting the aluminum. In this kind of furnace, a load placed on the hearth is heated by the vault, which radiates the heat produced by a burner. The burner is installed in the combustion chamber of the furnace, either in an adjoining compartment or in the vault, directly above the hearth. The melted load is collected in a kettle through a chute or across
a grille.

Four à réverbère

Old Powercast reverberatory furnace

The reverberatory furnaces were requiring more and more maintenance, and kettle furnaces are known for being more efficient. So, in summer 2012, in a first stage, two of the reverberatory furnaces were replaced by a kettle-type furnace. There is no vault in this type of furnace: the hearth and the kettle are one. In effect, the metal is melted directly in the kettle. A burner heats the external face of the kettle and the heat is diffused by conduction.

Four à creuset

Kettle furnace

This first modification led to a 15-20% reduction in the foundry’s total natural gas consumption. These very encouraging results convinced Powercast to go ahead and replace the remaining furnaces the following summer.

In this type of production, there are long periods of maintaining the temperature of the alloys. The kettle furnace is particularly efficient here, since the cover helps conserve heat. Also, unlike what occurs in a reverberatory furnace, the metal being smelted is not in contact with the products of combustion, so the heat losses in the chimney are limited.

Savings

It is difficult to carry out an energy efficiency analysis, since the ratio of energy consumption to aluminum production can vary considerably from one period to another for these reasons:

  1. The recording periods for the volumes of gas were slightly different from the recording periods for the quantities of aluminum produced.
  2. The effect of degree-days varies based on the level of production, since using the furnaces greatly contributes to heating the building.
  3. Over the last two years, the work being carried out in the plant has disrupted productivity, and the months of July 2010 and 2011 are not really representative of the foundry’s usual operating profile.

While the trend shows a reduction in consumption of almost 50%, an annual profile of the new installation needs to be created to demonstrate the improvement in energy efficiency. The following table is a comparison of similar periods that aims to isolate the gain in productivity by excluding variations due to the outdoor temperature.

As well as savings, the kettle furnaces offer the following advantages:

  • Less maintenance than with the old reverberatory furnaces;
  • A higher quality product due to more precise temperature controls;
  • A better quality work environment.

Conclusion

The total project required an investment of more than $200,000 by the customer. According to a model based on the figures for 2010-2011, the payback period for the investment can be shown to be well below two years. This report does not take into account the participation by the Canadian Industry Program for Energy Conservation (CIPEC, Natural Resources Canada) or by Gaz Métro, which both contributed to the project.

With energy savings of about 42%, including the furnaces and heating, the project helped Powercast increase its competitiveness, which will help the foundry increase the satisfaction of its current customers – and acquire new ones!

Charles Côté, Eng.
DATECH Group