Gas hydrate concentration measurements on sucrose solutions using a new pilot test rig

Abstract

A new 750 cm3 pilot test rig based on the “isochoric pressure method” was designed and commissioned for the hydrate measurements to concentrate sucrose solutions. The reactor included an improved agitation system and enabled sampling of the sucrose solutions. The experimental method was validated be performing dissociation measurements for the CO2 + water system. Gas hydrate kinetic and sampling data were measured for the CO2 + sucrose solutions at sucrose concentrations between (12–60) oBrix, within the temperature range of (274.65–276.15) K and at pressures up to 3.70 MPa. Results showed that sucrose is a kinetic inhibitor. The data were modeled to obtain hydrate formation rate, storage capacity, gas consumption and apparent rate constant. Stage‐wise concentration measurements were performed with reactor conditions at 274.65 K, 3.70 MPa and 130 rpm mixer speed with liquid sample withdrawal. A final sucrose product of approximately 60 oBrix was obtained.

Sugar cane juice concentration via CO2 gas hydrate formation

“…The schematic representation of the experimental apparatus used in this work is presented in Figure 1. Further details on the equipment are reported in a previous article 29 . The unit consists of a 750 cm 3 stainless‐steel reactor vessel enclosed by two flanges.…”

“…Further details on the equipment are reported in a previous article. 29 The unit consists of a 750 cm 3 stainless-steel reactor vessel enclosed by two flanges. The reactor vessel houses two polycarbonate windows to view the cell contents to track the hydrate formation.…”

“…As noted in our previous publication, the withdrawn sucrose samples from the reactor using mesh sizes of 38 and 45 μm also had bubbles appearing within the syringe. 29 During sample withdrawal for the sucrose experiments, the withdrawn samples also contained bubbles, which after some time, the liquid level decreased. This foam is due to its dispersion resulting from the release of the highpressure gas into the highly viscous sugar cane juice concentrate.…”

“…A batchwise experimental procedure was followed to concentrate the sugar cane juice as similar to the sucrose solutions reported in our previous work. 29 The experiments commenced with 0.12 mass fraction sugar cane juice, same as the feed to the evaporator train in the sugar factory. The composition of the liquid product obtained from each experiment was then utilized as the feed composition for the next stage.…”

“…The optimum conditions for the concentration of sucrose solutions via CO 2 gas hydrate were 274.65 K, 3.70 MPa, mixer speed of 130 rpm using a mesh size of 26 μm. 29 Hence, concentration studies on the sugar cane stages are required to achieve a maximum composition of 0.56 mass fraction from a starting feed solution of 0.12 mass fraction. An initial pH of 6.73 was measured for 0.12 mass fraction sugar cane juice feed and the product samples showed a decrease in pH after each experimental stage.…”