Tranter compact heat exchangers as condensate sub-coolers enable summertime cooling tower water to condense flash steam.
In summer many power plants lack the cooling capacity to condense adequately the steam outflow from the steam turbine. This results in steam flashing from the condensate and applying backpressure back through the turbine steam outlet. This backpressure can reduce turbine output by 20% or more, degrading the overall thermal efficiency of the power plant. Fuel consumption rises, along with carbon footprint.
Flashing the steam to relieve backpressure is wasteful in terms of energy and boiler treatment chemicals to replace this specially treated, highpurity feedwater. Reduced output is expensive for the utility, often making necessary the purchase of power from competitors to meet load requirements. The revenue opportunity is lost forever under these conditions.
Extra condensate cooling during hot months
Utilities are finding that replacing shell and tube exchangers with Tranter welded plate heat exchangers (WPHEs) installed downstream of the condenser eliminates the flashing and backpressure during the hot season. The exchanger’s efficient plate technology results in a small footprint than traditional shell and tubes. The increased turbulence of plate technology promotes higher heat transfer rates than with tubes, enabling the exchanger to make better use of lower grade cooling streams than is possible with shell and tube units.
Tranter WPHEs meet pressure and temperature challenges up to 100 barg (1450 psig) with lower hold-up volume, less weight and a significantly smaller footprint (usually 80% less area) than the S&T exchangers.
Impressive savings
In one recent installation, a Tranter WPHE condensate sub-cooler enabled the generating station to run at full output during the hot months, a performance rarely attained during the previous 35 years of operation. As a result, the customer achieved payback for the unit and its installation within the first year of operation.
Tranter WPHEs can reduce backpressure at the steam turbine outlet in seasonal condensate sub-cooling service.
Tranter WPHE condensate sub-cooler operating conditions
| PROPERTY | HOT SIDE | COLD SIDE |
| Fluid name | Condensate | Cooling Water |
| Flow rate, litres/min (GPM) | 4540 (1200) | 1515 (400) |
| Inlet temperature1, °C (°F) | 49 (120) | 18 (65) |
| Outlet temperature, °C (°F) | 39 (102) | 48 (118) |
| Total heat exchanged, kJ/hr (Btu/h) | 955 (10,492,905 | |
| Design/test pressure, barg (psig) | 31/40 (450/585) | |
| Design temperature, °C (°F) | 149 (300) | |
| Total installation space required, m2 (ft2) | <1.5 (<16) | |
1Unit brought on line when ambient temperature exceeds 10°C (50°F) and condenser outlet temperature exceeds 49°C (120°F)
