Continuous Eutectic Freeze Crystallization

Chivavava, Jemitias; Jooste, Debbie; Aspeling, Benita; Peters, Edward M.; Ndoro, Dereck; Heydenrych, Hilton; Pascual, Marcos Rodriguez; Lewis, Alison

doi:10.1039/9781788013581-00508

Cited by 2 publications

(1 citation statement)

References 32 publications

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“…Eutectic point is the operational point where the composition of a solution that consist of lowest temperature of crystallization than any other composition of the same wastewater with the composition and temperature being below that of the solvent and solute which crystallize out from the wastewater. Depending on the concentration of salt, different wastewater/brine have different eutectic compositions and temperatures [17].…”

Section: ) Freeze Crystallization As An Alternative To Evaporationmentioning

confidence: 99%

Treatment of Flue Gas Desulphurisation Effluent with Freeze Crystallization

2022

35th JOHANNESBURG International Conference on “Chemical, Biological and Environmental Engineering” (ICCBEE-22) Nov. 28-29, 2022

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Kusile was the first power station of Eskom to implement a wet flue gas desulfurization system for the control of SO2 and other greenhouse gasses. The waste water from the flue gas desulfurization (FGD) plant contained a high total dissolved solids (TDS) concentration of 50 000 mg/L due to: (i) absorption of SO2, chloride and boron from the coal to the FGD waste water, (ii) dissolution of sodium, potassium, magnesium, manganese and calcium form the limestone when reacted with the acid gasses from the combustion chamber. A large portion of the calcium sulphate in solution precipitated as gypsum due to its limited solubility.The study focused on disposal, electrical and chemical cost of three FGD waste water management methods. It was found that the cost for a 4 800MW plant will amount to R9.7 million per month for disposal at a toxic waste disposal site, R11.41 million per month when pre-treated with lime/sodium carbonate followed by evaporation and R0.96 million per month when treated with Freeze crystallization. Freeze crystallization was found to be the most cost effective as it did not need chemical pre-treatment and it consumes less energy than evaporation (330kJ/kg in the case of freeze versus 2 260kJ/kg in the case of evaporation). Energy usage was found to be 100 kWh/kg ice. The TDS of the Feed amounted to 50 000 mg/L compared to less than 3 000 mg/L in the melted ice.

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Section: ) Freeze Crystallization As An Alternative To Evaporationmentioning

confidence: 99%

Treatment of Flue Gas Desulphurisation Effluent with Freeze Crystallization

2022

35th JOHANNESBURG International Conference on “Chemical, Biological and Environmental Engineering” (ICCBEE-22) Nov. 28-29, 2022

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Effect of Heat Transfer Driving Force and Ice Seed Loading on the Production of Ice and Salt from a Dilute Brine Treated Using Eutectic Freeze Crystallization

2022

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Eutectic Freeze Crystallization (EFC) is a separation technology that separates solute from solvent by cooling the brine to a temperature below its eutectic point, such that ice and salt simultaneously crystallize out of the solution. Achieving consistent production of ice and salt at high production rates has been a challenge for EFC. This is due to heat transfer limitations, which are more severe when EFC is applied to dilute brines. This work investigated the effect of the heat transfer driving force, ΔTLMTD, and ice seed loading (SL) on the production of ice and salt from a dilute brine. A 1.45 L stirred crystallizer was used for the experiments at varying coolant temperatures to investigate the effect of ΔTLMTD, and at varying seed masses to investigate the effect of seed loading. It was found that, as the ΔTLMTD increased, the yield of ice and salt increased. This was attributed to the increase in the heat transfer rate as ΔTLMTD and heat transfer rate are directly related. The ice yield was divided between ice in suspension and ice formed on the wall (scale layer), with a majority of the total ice yield being scale ice. Increasing the seed loading (SL) increased the yield of ice in suspension and decreased the yield of scale ice. The seeds allowed for increased surface area for crystallization in the bulk. This allowed for most of the supersaturation to be consumed in the bulk, leaving little supersaturation for crystallization at the wall. This reduced the propensity for scale formation. The reduction in the scale layer increased the heat transfer rate between the bulk and the coolant, allowing for more ice to be formed in suspension.

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Continuous Eutectic Freeze Crystallization

Cited by 2 publications

References 32 publications

Treatment of Flue Gas Desulphurisation Effluent with Freeze Crystallization

Treatment of Flue Gas Desulphurisation Effluent with Freeze Crystallization

Effect of Heat Transfer Driving Force and Ice Seed Loading on the Production of Ice and Salt from a Dilute Brine Treated Using Eutectic Freeze Crystallization

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