Why is it worthwhile to return as much condensate as possible to the boiler?
- It is cold and dense, so it pumps more easily
- It is hot and pure, saving fuel and treatment
- It is high in oxygen, which protects the tubes
- It is high in hardness, which coats the shell
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B. It is hot and pure, saving fuel and treatment
Condensate is nearly distilled water that still holds a good deal of heat, so reusing it cuts fuel, makeup water and chemical use. It is not cold; it normally returns well above the makeup water temperature.
Reference: Feedwater systems: condensate return
On the feedwater line to a boiler, which arrangement of valves is correct?
- Stop valve next to the boiler, then the check valve
- Check valve next to the boiler, then the stop valve
- Two check valves in series and no stop valve
- A single stop valve and no check valve at all
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A. Stop valve next to the boiler, then the check valve
The stop valve goes between the check valve and the boiler so the check valve can be isolated and repaired without draining the boiler. With the check valve nearest the boiler there would be no way to work on it under pressure.
Reference: ASME BPVC Section I, PG-58.3 (feedwater piping valves)
What is the purpose of the check valve in a boiler feedwater line?
- To throttle the feedwater flow to match the load
- To stop boiler water flowing back out the feed line
- To relieve any excess pressure in the feed pump casing
- To strain out scale before it reaches the boiler
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B. To stop boiler water flowing back out the feed line
The check valve opens only toward the boiler, so boiler pressure cannot push water back through the feed line when the pump stops. Throttling flow is the job of the feedwater regulating valve.
Reference: ASME BPVC Section I, PG-58.3