© MANTRA Innovative Systems 2013
Tomorrow's Energy Solutions.
TEXTILE FACILITY LOOKS TO RECOVER ENERGY FROM WASTEWATER DISCHARGE & DRYER EXHAUST SYSTEMS
Energy consumption in the textile industry is most commonly found in the forms of: electricity, as a common power source for machinery and control systems; oil as fuel for boilers which generate steam; liquefied petroleum gas; coal; and city gas.
The production processes involved in dyeing and finishing, fiber production, spinning, weaving, and clothing manufacturing utilize vast amounts of energy that can be recovered to reduce the operational costs of a facility.
The textile manufacturing industry has one of the lowest efficiencies in energy utilization because it is largely antiquated. As a whole, the textile industry spends between 4-6% of net income on capital expansion and modernization.
- Provide the energy for 80,000 gallons per day of makeup water for the boilers with the temperature of the process water to be increased from an ambient temperature of 50°F to 120°F.
- Reduce the temperature of the discharged wasterwater to less than 110°F to comply with the local municipal wastewater requirements. The facility was currently operating with a wastewater discharge volume in excess of 175,000gpd and an average temperature of 130°F.
Wastewater temp in: 130° F
Wastewater temp out: 110° F
Process air temp in: 60° F
Process air temp out: 130° F
Water mass flow: 148,000 Kg/h
Air mass flow: 30,000 SCFM
Energy recovered: 712 kW/h
Payback period: 12 months
After reviewing the client’s processes, MANTRA was able to indentify two major areas where energy could be recovered. MANTRA designed a unique two-stage energy transfer unit that was capable of meeting all of the criteria established by the company.
The design proposed required the heat transfer unit to be inserted directly into the wastewater collection system. The wastewater flow of 175,000gpd at 130°F provided a usable energy source of 1909 kW.
The energy recovery system designed is a water-to-water heat exchanger that provides a constant 3,333gph of makeup process water at 125°F utilizing 658 kW/h
The wastewater discharge temperature was reduced from 130°F to 100°F saving the company the cost of cooling the wastewater before discharging it into the municipal wastewater system.
Each system had a target return on investment of 24 months and the actual returns on investment were 12 and 13 months.
This textile manufacturer sought a means by which it could reduce operating costs by recovering and reusing some of the massive amounts of energy used in production. After an evaluation, MANTRA identified the wastewater discharge and dryer exhaust systems as available sources for energy recovery. Another objective of this project was to use the energy transfer technology to reduce the temperature of the liquid waste stream before discharge in order to comply with local regulations.
Wastewater temp in: 130° F
Process water temp post exchanger: 50° F
Outlet wastewater temp: 100° F
Return process water temp: 125° F
Wastewater mass flow: 148,000 Kg/h
Process water flow rate: 13,600 SCFM
Energy recovered: 658 kW/h
Payback period: 13 months