Pressure after the steam trap
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I would like to ask fellow sailors: if the pressure behind the steam trap is lower than the pressure before it, will there be significant flashing of condensate after it passes through the steam trap? Is it the pressure of the condensate behind the steam trap that determines the pressure in the condensate drainage system, or is it the pressure of the drainage system that determines the pressure behind the steam trap? I appreciate your guidance
Some water will definitely vaporize behind the steam trap, but not in large quantities. The resistance of the steam trap can be estimated at 30~50 Kpa; you can calculate the amount of flashing. Additionally, all steam traps will have some degree of steam leakage. So you will see some groundwater tanks that collect condensed steam starting to emit white vapor into the air. The pressure comes from the boiler, of course; it’s similar to how the pressure of a liquid comes from the pump. So the pressure is determined by the boiler; as for how much pressure remains when the steam condenses into water, it depends on the pressure loss in the pipes leading to it.
Agree with the person above! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !
The pressure behind the check valve is the back pressure plus flow resistance. Apart from constant-temperature traps, most traps discharge water as soon as it appears, so steam flashing is inevitable afterward.
This post was last edited by Still in the Mood for Youth on 2015-9-14 at 10:54. The principle of flashing is based on the law of conservation of energy. For example, the saturated temperature of condensed water at 5 bar is 159°C; therefore, 1 KG of water contains 671 KJ of energy. Behind the steam trap, the pressure is at atmospheric level, so the water can hold at most 419 KJ of energy. This results in a violation of the law of conservation of energy, with an excess of 671–419 = 252 KJ of heat. Such excess heat inevitably causes the water to become superheated, leading to flashing. The pressure is determined by the pressure behind the valve
Vaporization does occur, but not in large amounts. If the pressure behind the steam trap is too high, it indicates that the steam trap is not functioning properly and steam is getting through.
I have a question: the pressure of the condensate after steam condensation should be the same as the steam pressure, and since there is only a small pressure drop across the steam trap, the pressure after the steam trap, minus the losses in the pipes, shouldn’t be very low either. So I’m not sure how to determine the pressure in the condensate collection system
Currently, the steam volume is 60 kilograms. The condensate goes to the condensate flash tank, whose capacity is 6 kilograms. Could the pressure of the condensate after passing through the check valve and due to pressure drops in the pipes be higher than the pressure in the condensate flash tank (the design pressure)? That would be unreasonable
Does the flash tank have a vent pipe for the flash vapor waste gas, so that overpressure does not occur? Could the experts upstairs give an example calculation?
There is some flashing after the steam trap; it’s a backpressure relief and vaporization process, but it’s not significant.
The back pressure behind the steam trap is related to your system downstream of the valve