Energy Calculation

Dear Abdul shakoor

To calculate the mass flowrate of steam required to vaporize the liquid; you don't need the size of the heat exchanger just do an energy balance:

Q= massflowrate of steam x (h1-h2) steam = massflowrate liquid x (h1 - h2 )

Steam data from steam tables :

At t= 320 °C; P= 28 Psia (superheated steam) h=1199.4 btu/lbm

at saturated vapor state and P= 28 Psia T= 246.4 F and h= 1162.9 btu/lbm

at saturated liquid state and P= 28 Psia T= 246.4 F and h= 214.9 btu/lbm

Then you have to identify the liquid (water? hydrocarbon?) to determine its specific heat or the enthalpy variation.

Important :

-Don't forget shell and tube sides head losses

- the inlet steam should be near its saturated vapor state

- the outlet steam should be near its satirated vapor state

For the control of the heat exchanger it depends on the parameter you want to maintain constant. Let's suppose that the controlled parameter is the oultlet liquid temperature in this case we install a temperature control valve in the outlet water condensate pipe and with a TIC controller in order to keep the controlled parameter constant.

Send me your e-mail to bouzidkamelbenalli@yahoo.fr with additional information (nature of liquid, parameter to control)

Regards

BOUZID KAMEL

PROCESS ENGINEER, SONATRACH, ALGERIA

In addition to other replies, the temperature of the condensate will be at, or just below, the saturation temperature of the steam being used at the pressure supplied. There is no point in re-heating it locally as it will boil, and there is a steam supply to the process already. Why not just use more steam (rhetorical question)? Sub-cooling will involve using a source of "coolth", such as a cooling water loop, and a heat exchanger. Why does the condensate temperature need to be reduced (rhetorical question)? If the condensate were to be returned to the boiler for re-use at the highest possible temperature then economies in boiler operation will ensue. BTW: "Don't try and lift condensate" applies. If the condensate is to be re-used, a return pump (such as a steam-powered "Ogden Pump") will prove a valuable piece of equipment to install, if indeed it isn't installed already.