SECOHYA Project

Experimental set up

The experimental set-up is a classical batch reactor. The cell is a pyrex cylinder that is filled with a volume of 800 mL to 1 L of water, TBAB and an anionic tracer. It is located in the stainless steel autoclave in which the pressure can be raised up to 10 MPa. The autoclave is surrounded by a cooling jacket. Two sapphire windows mounted on both sides of the reactor make possible observation. A four vertical-blade turbine impeller ensures stirring of the suspension during crystallization.

Temperature is monitored by a Pt100 probe in the bulk. Pressure is measured by mean of a pressure transducers (range: 0–10 MPa). The data acquisition unit is also connected to a personal computer through two National Instruments cards. The composition of the gas phase is determined using gas chromatography. Gas sampling is performed by the way of a ROLSITM instrument. This tool collects a controlled volume of gas (some m3) which is directly injected in the loop of a gas chromatography (VARIAN model CP-3800 GC) equipped with a thermal conductivity detector (TCD) and two analytical columns (PoraBOND Q and Molsieve 5A). A classical valve is used to take a 1-ml sample for determination of TBAB concentration by refractive index measurement. The other part of the liquid sample is directed to DIONEX ionic chromatography to measure the tracer concentration (the tracer is an ionic element which is not incorporated in the hydrate structure but concentrated in the liquid phase during crystallization).