Condensate Return

1- If 98 barg condensate is returning and after steam trap it directly goes to Flash Vessel which is at 5 barg. What would be the pressure at the down stream of the Trap, is it 98 barg or 5 barg.

Depends on size and length of pipe to some extent but basically near the low end of the range.

2- LP condensate of 5 barg goes directly to Condensate Return Tank after passing through Control Valve. What would be the Pressure at the down stream of the Control Valve.

Essentially that of the C. R. Tank.

Thanks Stan . All I know that's its an ICI Plant.But i'm wondering at 98 bar condensate pressure?

At such a high steam pressure they must be driving a turbine and a back pressure steam may be coming out at 5 bar from the top of a tank/ Flash Vessel and therefore, the condensate coming out from the bottom if installed with a drain trap will be anywhere between 5-25 psi (sized at inlet 5 Bar) depending on the backpressure due to the length of the pipes etc.

They also mention a Control valve ? Why do they a need a Valve? If they are controlling it with a temperature controller then what happens when it goes shut?What is this valve actually doing unless they are supplementing steam shortfall- maybe.These are some of the things I need to see.As far as the pressure is concerned this will be 20-35% less then the inlet due to the control valve orifice differential lossses.

Anyway thanks, when I see the system, I'll keep your views handy.

As stated in the former reply, the downstream pressure in each case will be 5 barg, except for the pressure drop due to piping to the flash vessel. You can calculate the temperature just downstream of the valve, if important, if you know the temperature of the condensate at 98 barg. Once the condensate flashes in the valve, you will have a mixuture of water at saturation temperature and steam. This is an adiabatic process where heat (BTUs or calories, not temperature) is neither lost nor gained. You can do a heat balance by taking enthalpy of the condensate from a set of steam tables, and subtracting the enthalpy of water at saturation temperature at 5 barg. The missing enthalpy is in the steam.

Bernie Katz

PS: Your application is tough for a valve to take. 98 barg is 1420 PSIG. There are multistage and "torturous path" valves made for the purpose. The old way is to use a valve with a stellited plug and seat, but the noise will be horrendous.

Berniek buddy Thanks. Agree with bth Stan & You. Best Rgds