What are Steam Condensate Return Pumps?
Steam condensate pumps are mechanical, non-electric pumps which recycle condensate to the boiler feed tank. They utilize a float valve to inject high-pressure steam to push accumulated condensate through the condensate return system.
Steam condensate return pumps efficiently conserve energy and reduce CO2/NOX emissions by collecting and returning hot condensate for reuse as boiler feedwater. This treated condensate reduces the need to add cold make-up water and water treatment chemicals and reduces energy loss from boiler blowdown.
Resources
Steam Condensate Pump Operation
1. Pump body is empty.
- Condensate flows by gravity from reservoir through the inlet check valve
- The internal float begins to rise as the pump body fills
2. Condensate has filled the pump body.
- With a “Snap Action”, the float and internal linkage are engaged to simultaneously close the outlet exhaust port and open the inlet steam port
3. Steam flows into the pump body.
- The inlet check valve is closed and the outlet check valve is open as condensate is forced out of the pump body into the condensate return system
- The float falls as the liquid level in the pump body drops
- At the lowest tripping position, the linkage simultaneously closes the steam inlet port and opens the exhaust port to repeat the filling cycle
Advantages and Disadvantages Versus Centrifugal Pumps
Advantages of a Steam Condensate Pump:
- Condensate can be returned at temperatures well above the 210F limit of the conventional electrical pump. This results in less flash steam loss together with sensible heat savings and up to 20% reduced energy costs.
- Increased reliability - Steam motive pumps have no seals to wear out
- No cavitation
- Excels in hazardous and wet locations
Disadvantages of a Steam Condensate Pump:
- Higher initial cost
- Less compact - steam-operated pumps require a larger receiving tank which increases the size and required headroom
Why Return Condensate?
Recycling condensate to the boiler is a common method of meeting profitability and sustainability goals with a fast return on investment. Maximizing condensate return improves key performance indicators including boiler blowoff and makeup water rates.
- Condensate is significantly warmer than makeup water. Less fuel is needed to generate steam, saving energy costs and reducing CO2 emissions.
- Condensate is already treated so chemical treatment and blowoff can be reduced.
- Recycled condensate reduces the amount of new water needed, reducing costs and assisting sustainability targets.
One paper plant reduced its makeup water rate from 35% to roughly 17%, saving more than $300,000 annually.
FAQs
- Total Condensate Load coming from the steam traps
- Total Backpressure on the pump (condensate return pressure + the hydraulic head pressure to lift the condensate to the condensate return line)
- Inlet Motive Steam Pressure
- Height of Existing Equipment (will be used to determine the available fill head between the bottom of the vented receiver and the top of the pump)
Steam condensate pumps do not contain seals or impellors which are prone to damage in condensate service.
Steam traps require positive pressure differential to drain condensate. When the pressure within the heat exchanger drops too low, the condensate accumulates flooding the heat exchanger. This heat exchanger stall causes challenges controlling the process temperature as well as water hammer damage and corrosion within the heat exchanger.
The Yarway™ CondenSaver™ pump trap option uses steam to remove condensate in all conditions, eliminating heat exchanger stall.