Waste heat recovery comes to sludge

Dresser-Rand Company recently designed and installed a complete waste heat recovery system at the Greater New Haven Water Pollution Control Authority (GNHWPCA). The project included engineering, construction and testing of the waste heat boiler, steam turbine generator set and condenser, ducting and valves. The system is expected to produce 4.4 million kW hours of electricity per year.

The Dresser-Rand project uses waste heat from the wastewater treatment facility to produce steam, powering a Dresser-Rand 750 kW steam turbine generator at the East Shore Water Pollution Abatement Facility. As a result of the project, GNHWPCA expects to reduce its electricity costs by one-third.

Said Peter Salvatore, Vice President, Global Field Operations at Dresser-Rand, “We estimate this type of power recovery solution could be viable for 200 similar facilities in the U.S. And while this project falls on the smaller end of the power scale, Dresser-Rand has equipment and capabilities exceeding 60MW.”

The GNHWPCAwater treatment process involves removing sludge, or sewer system waste, from the water, reducing the moisture content to a combustible level, and burning the dried sludge in a multiple hearth furnace. The resulting exhaust gas is scrubbed to remove pollutants and then released to the atmosphere.

Dresser-Rand’s waste heat recovery solution routes the exhaust gas directly from the furnace to a waste heat boiler, creating steam. The steam powers the turbine generator set, producing electricity in a closed loop cycle. The exhaust gas is returned from the boiler to the scrubber and out the exhaust stack. The process is designed such that it does not change emissions and, therefore, does not impact the facility’s air quality permit. The system simply diverts the gas upstream of the scrubber, extracts a significant amount of the otherwise wasted heat and returns the gas back to the scrubber to continue its normal exhaust path.

This project is Dresser-Rand’s first complete service installation at a sludge incineration facility.

More info:  www.nebiosolids.org