Waste heat re-use produces significant savings

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Using dissipated heat from a central air compressor to provide heat for plating significantly improved energy efficiency at ASSA ABLOY Zhongshan’s manufacturing site.

Challenge

At ASSA ABLOY Zhongshan’s manufacturing site in China, there is a central air compressor whose total power is about 300KW. However, it generates a lot of heat and nearly 60 percent of electric energy was wasted due to heat dissipation.
In the meantime, the site also has a plating process which requires 0.5 tons of diesel every day to heat up water to 82°C. ASSA ABLOY Zhongshan wanted to reduce the diesel consumed in order to save energy.

Solution

A waste heat recovery system was installed to utilize the heat generated from the air compressor to heat up water, which is then supplied to the plating line. Using the waste heat, no extra energy is needed for the water to reach 82°C. The system not only reuses the waste heat generated from the central air compressor, but also reduces the amount of diesel consumed in the plating line.

Result

After the waste heat recovery system was installed in June 2014, it became the major source of heat for the plating line, and diesel is the auxiliary source. The diesel consumed was reduced by 0.3 tons every day. The new system results in an estimated cost saving of CNY 675,000 (EUR 88,700) per year through reduction of diesel consumed.

In addition to cost savings, the waste heat recovery system helps reduce the emission of poisonous gases like carbon dioxide, sulphur dioxide and nitrogen oxides, because less diesel is burnt. Now the site has become a cleaner and safer workplace.