Condensate is exhausted heat steam and for the reasons already expressed, returning it to the boiler results in meaningful energy savings. Actually, condensate cannot be allowed to accumulate in equipment, especially heat exchangers. These devices are designed to operate non-flooded and accumulated condensate inhibits heat transfer performance and induces corrosion. Prompt condensate removal, just after formation, is provided by steam traps. Besides heat transfer problems, simultaneous flow of steam and water in the same pipe may lead to erosion and water hammer in the pipework. Water hammer occurs when slugs of water travel down the pipe at steam speed, that is usually much higher than water velocity design. Reaching pipe accessories and direction changes may lead to disruption of the pipe and eventually accidents. Condensate is saturated water at a pipe inlet, but with flow, pressure drops and steam evolutes. If the pipe is long, there are chances that water hammer will happen.
Above all considerations over condensate recovery observed in this text, a single utmost warning prevails for condensate flow. Prevent near saturation condensate to flow just by system pressure differential. It may be not enough to avoid water hammer conditions and at the least, may not allow condensate to flow to a proper collection spot. Best practice here is to always have an extra driver for this flow. One is to take advantage of gravity, making condensate flow from higher to lower grounds. Condensate recovery lines must always be connected to pipe headers by the top. Never connect condensate from different steam pressures to the same header without good analyses. There might be moments that some streams will be facing a higher pressure ahead, and they will not flow, creating a dead spot where corrosion pops. And if there is chance that no nearby recovery header can stand the pressure of the condensate generated, flash it.
When condensate at a high pressure is released to a lower pressure, it produces flash steam at a lower temperature and low pressure condensate. This steam can be as useful as that produced by a boiler, being sent to a heating process or simply vented to atmosphere. The residual hot condensate can then be pumped to a collecting tank and eventually treatment and then back to a boiler. The pumped condensate pipe is fully flooded, meaning that water hammer is less likely to occur. These cares begins in design and system improvement and are fundamental to grant huge and continuous energy savings.
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