Liquid solutions throttle

Solution Throttling to 0.5 bar. At inlet conditions water is a compressed liquid. Recall that for compressed liquid away from the critical point, an isotherm is also a line of constant volume, constant enthalpy, and constant entropy. The enthalpy at state 1 is then approximately equal to that of the saturated liquid at 60 "C. Using steam tables we find if,= if<6o °C) = 251.1 kJAg- At the exit, water is still compressed liquid because it is above the saturation pressure, which at 60 °C is 0.1992 bar. Since a line of constant enthalpy in the compressed region is also a line of constant temperature, T. = T, = 60 "C. 

The liquid mass flow rate with the concentration Xq is fed in to the first effect with the pressure p. The concentration increases due to the evaporation of the solvent. The hquid mass flow rate L with the concentration x, is throttled by means of a valve and assumes the pressure P2 The vapor mass flow rate G, = Zq leaving the first effect enters the heating element of the second effect and is condensed according to the progress of heat transfer. It is assumed that the entering liquid solution is imdercooled and that a certain increase of its enthalpy is necessary to start boiling at pressure. The heat flow rates Q and Qi based on the mass flow rates Zq and L, respectively, can be expressed by the following enthalpy differences ... 

On a laboratory scale, supercritical fluids may be contacted with a substrate on a once-through basis. Typically, the pressurized fluid is heated and passed through a chamber containing a solid or liquid sample. The desired solute selectively dissolves in the pressurized fluid and is transported out of the chamber and through a throttle into a container where the pressurized fluid evaporates at atmospheric pressure, leaving a solute residue in the container. 

Before proceeding to offer a solution to a general problem, we will try to estimate the volume of liquid phase formed on the basis of a simplified statement. Assume that coagulation and condensation growth of drops in the throttle are absent and that the flow is adiabatic. The distribution of flow parameters is then described by the following equations ... 

I have spent many fruitless hours trying to set such a control valve. In practice, operating personnel will not be able to put such a control valve in a proper position routinely. Even if the control valve is set correctly, a small increase in the condenser operating temperature will cause vapor to start blowing through the throttle valve again. The only permanent solution is to install an accumulator drum between the condenser and the throttle valve. The throttle valve will then be controlled by the accumulator drum liquid level. 

Samples of liquid and suspended solids will be taken from the high- and low-pressure. systems of the HRE-2. Solution from the high-pressure system is reduced in temperature and pressure from 300°C and 2000 psi to approximately 80°C and 1 atm by a cooler and throttling valve before... 

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