Treatment and disposal are two main approaches for water cycle management in the oil and gas industry. Freeze concentration has been identified as one of the methods to separate water from wastewater samples. The conventional method used for solution movement in progressive freezing technique is stirring by a stirrer. However, the stirrer requires frequent maintenance as it needs to be cleaned and requires longer cleaning time due to the complex structure of a stirrer. Thus, the new solution movement for progressive freezing is proposed, which is circular moving progressive freezing. This study aims to remove water from the wastewater sample (i.e., produced water). To optimize and investigate the effect of coolant temperature, freezing time and rotation speed, response surface methodology (RSM) was applied to determine the efficiency of the process and central composite design (CCD) was used to design the experiment. From the results, the optimum parameters were determined at the freezing time of 22.79 min, coolant temperature of −14.89 °C and rotation speed of 59 rpm. To evaluate the accuracy of the optimization process, a validation experiment was performed and water removal value of 89.67% was achieved.

Optimization of progressive freezing on synthetic produced water by circular moving cylindrical crystallizer via Response Surface Methodology

In this industrial era, salt recovery from seawater has become an important issue from the environment perspective. Few freezing technologies have been proposed as capable way to separate the salt from the seawater because of the energy used in the previous technologies is higher. A study of Progressive Freeze Concentration (PFC) and Eutectic Freeze Concentration (EFC) method have been carrying out and further investigated on their performance in recovering the salt. For the PFC method, pure water crystallizes into crystal and the concentrate is left behind as in liquid form while for the EFC method, both ice crystals and salt crystallize at the same time when the initial concentration of water salt mixture is exactly the same as eutectic concentration. In EFC, salt sinks to the bottom while ice floats at the top of the crystallizer and both are separated by gravity separation. Effective partition constant and solute recovery are calculated to evaluate the efficiency of PFC and EFC. In this study, the PFC method has shown an effective partition constant of 0.28 and recovered solute of 0.88 g of sodium chloride per 1 g of initial sodium chloride while for EFC method, effective partition constant and solute recovery obtained are 0.59 and 0.66. Overall, both techniques are applicable for the seawater desalination process.

Study of progressive freeze concentration and eutectic freeze crystallization technique for salt recovery

Behaviours of ice crystal growth at two different operating parameters namely coolant temperature and circulation time were investigated for progressive freeze concentration (PFC) of glucose solution through a vertical finned crystallizer (VFC). Two determinant parameters which are ice production rate (mu), and water recovery (WR) were used to illustrate the behaviours of ice crystal growth in this study. From the result, higher ice production rate (mu) and water recovery (WR) were achieved at lower coolant temperature. On the other hand, longer circulation time resulted in lower ice production rate (mu), but at the same time increased the water recovery (WR). The maximum ice production rate (mu) and water recovery (WR) attained through this study were 1.522 gm-2s-1 and 51.131 %, respectively.

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Behaviour of Ice Crystal Growth in a Vertical Finned Cylindrical Freeze Concentrator

Progressive freeze concentration (PFC) has emerged as a viable technology for concentration of liquid solution. In this study, a newly designed spiral finned crystallizer to improve productivity of PFC process was proposed. The spiral fin is presented based on the advantage of additional surface area to the spiral finned crystallizer. The performance of spiral finned crystallizer was analysed by the system efficiency and the effect of circulation flowrate. It was found that the efficiency of the system has significantly improved in terms of a lower effective partition constant and a higher recovered solute. An effective partition constant of 0.35 and a recovered solute of approximately 0.96 g of glucose per 1 g of initial glucose were obtained. Thus, spiral finned crystallizer for PFC system is evidently an effective system to concentrate solution and to produce pure ice crystal.

https://www.akademiabaru.com/wvcarmea/docu/131.pdf

Amran Nurul Aini

Papers

Behaviour of Ice Crystal Growth in a Vertical Finned Cylindrical Freeze Concentrator

Effect of Circulation Flowrate on the Performance of a Spiral Finned Freeze Concentrator