PT Lab

Unit for the collection of experimental data of vapor-liquid equilibrium (VLE) and of vapor-liquid-liquid equilibrium (VLLE) of multicomponent mixtures.

The facility is composed of a unit for Vapor-Liquid Equilibria Fisher® Labodest® VLLE 602 and a gas chromatograph Agilent 7820A, with a TCD detector. The VLLE unit is an all-glass recirculating still that ensures that both the liquid phase and the vapor phase are in contact during boiling and in contact with the temperature probe. The system can be used at atmospheric pressure, vacuum and overpressure conditions up to 400 kPa. The equilibrium temperature is measured with a digital temperature logging module and a Pt 100 resistance thermometer. The accuracy is ±0.1 K and the resolution is 0.01 K. A precision pressure transmitter is used to measure and control the pressure in the equilibrium cell, with a pressure accuracy of ±10 Pa. This apparatus allows reaching pressures higher than atmospheric pressure (up to 400 kPa) by injection of high purity nitrogen, under pressure control of two manual valves and under automatic control.

Unit for the collection of experimental data of solubility of gases in liquid solvents.

The unit consists in two sections, one for the collection of experimental data at pressures up to 50 bar (on the left side) and one for the collection of experimental points for systems forming two liquid phases up to 8 bar (on the right side). Each section operates with two cylindrical vessels: - the first one (D1), that is common to both the sections, is filled in with the gas to be absorbed into the solvent, i.e., CO2; - the second one, one for each section (D2 for the high-pressure tests and D3 for the biphasic solvent tests), is filled in with the solvent and is the unit where the phase equilibrium occurs. The vessel D1 is equipped with a temperature and a pressure sensor (TE10 and PT20, ranging from 0 to 60 barg, with a precision equal to 0.2% of the maximum value) and it is connected directly to the gas feeding line of CO2 and of N2. The CO2 bottle and the N2 bottle are stored in an external dedicated room. The vessel D2 and the vessel D3 are connected to the vessel D1 and are provided with a magnetic stirrer to mix the liquid inside the unit and with a temperature sensor and pressure transducers (several pressure transducers are installed with different operating range, each one with a precision equal to 0.2% of the maximum value), to determine the variation of the operating conditions during time. They are located in a steel container with a removable lid where the thermostatic oil circulates after opening the valve, to keep the temperature at the given value set on the thermostatic bath. A “too full” tank is present so that if the circulation tube gets clogged and oil starts accumulating in the tubes or in the vessel, it can exit without flooding. In addition, a vacuum pump is installed for decreasing the pressure before and after the charging of the solvent mixture at the beginning of the experimental test. A N2 line is present to improve the efficiency of the discharge procedure (to avoid additional solubility of CO2 if using this gas for the discharge) and to make the system inert before the beginning of a new experiment.

The Process Thermodynamics laboratory – PT lab of Politecnico di Milano has been created within the ICE (Ingegneria Chimica – Energia) collaboration.

It is held by Prof. Stefania Moioli (GASP – Group on Advanced Separation Processes and GAS Processing) and Prof. Davide Bonalumi (GECOS - Group of Energy Conversion Systems).

It is an experimental facility for the collection of data of:

• vapor-liquid equilibrium (VLE), vapor-liquid-liquid equilibrium (VLLE) of multicomponent mixtures;
• liquid-liquid equilibrium (LLE) of multicomponent mixtures;
• solubility and diffusivity of gases (e.g., CO2) in liquids (solvents);
• properties (density, viscosity, pH, etc.) of liquids.