Lachine
Quebec, Canada - Ground-source heat pump
| Summary Due to the implementation of the water treatment system at the Lachine steel factory sludge disposal is necessary. The sludge is contaminated with lead and zinc from the process and has high water content (50%). Three options were looked at for an effective way to drain the sludge for a more economic transfer and landfill disposal. A gas dryer seemed very expensive and complex to both install and operate. A heated screw conveyor performed well but required further development. A heat pump appeared most advantageous with its high energy-efficiency and instant installation. It has been estimated that a more than 40% weight reduction in sludge is achieved with the system. |
Industry / process
| Industry type: | Steel manufacturing | |||
| Location: | Lachine, Québec, Canada | |||
| Description of the process: | No data | |||
Heat pump system
| Application: | Sludge drying | |||
| Heat pump type(s): | No data | |||
| Heat pump installed capacity (kW) | No data | |||
| Drive energy: | No data | |||
| Refrigerant: | No data | |||
| Heat pump system completion date: | January 1996 | |||
| Description of the heat flows: The system consists of a compressor, heat exchangers and ventilator. The dry air becomes moist when circulated through the sludge. Air is then passed through a condenser (evaporator of heat pump), which extracts water from it. After this the air is passed through a heat exchanger (condenser of heat pump), which heats the air to a set temperature. The system operates in a closed loop. Its components are placed in a compact cabinet, which is connected by three flexible pipes to the tank containing the sludge. Once drained, the sludge is transferred to a landfill site. |
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Performance
| Energy | |
| Heat pump drive energy (kWh/year): | 123 600 (heat pump’s efficiency for recovering thermal energy is 98%) |
| Fuel: | No data |
| Energy output, useful heating (kWh/year): | No data |
| Energy output, useful cooling (kWh/year): | No data |
| Energy cost (CAD/kWh) : | 0.037 |
| Coefficient of performance (COP): | No data |
| Heat pump cost breakdown | |
| Heat pump only (CAD): | Heat pump total CAD 45 000 |
| Installation (CAD): | |
| Capital cost (excluding heat pump) (CAD): | |
| Maintenance: | No data |
| Alternative system (if has been considered) | |
| Type: | Gas dryer |
| Energy input (kWh/year): | 420 000 (efficiency for recovering thermal energy is 50%) |
| Capital cost (CAD): | 100 000 |
| Installation cost (CAD): | 20 000 |
| Maintenance cost: | Energy cost CAD 7200/year |
| Annual CO2 emissions (kg CO2/year): | No data |
| Payback | About 1 year based on transfer and landfill charges. |
| CO2 emissions | The annual CO2 emissions are 51 tons less than for a conventional gas dryer. |
Operational experience and other comments
Very little maintenance is necessary.
The company saves CAD 50 000 each year in transfer and landfill charges.
Contacts
This case study is from Caddet web site
http://www.caddet.org.
| Last updated: 1 March 2004 |
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