Design of a wastewater purification system based on freezing
Choudhury, Tuhin (2018)
Diplomityö
Choudhury, Tuhin
2018
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe201801222163
https://urn.fi/URN:NBN:fi-fe201801222163
Tiivistelmä
Freeze crystallization is a natural and environmental friendly alternative to other conventional wastewater purification processes. In this study, the main objective is to determine the critical issues with direct and indirect form of freeze crystallization and to develop a pilot plant model for a freezing based wastewater purification plant. For this purpose, experimental studies were conducted on crystallization and separation of wastewater by direct contact freezing (DCF). Cold air from a vortex tube was used as the refrigerant for convenience. The main issues identified were formation of ice lumps at the point of dispersion and insufficient heat transfer at four bar pressure. The issue was mitigated by using Teflon as base material due to its ice-phobic properties. To further resolve the issue, polyurethane coating was used and as per calculation, air pressure of 20 bar is required through multiple inlet points in order maintain continuous ice production. Furthermore, experiments suggested that the usage of a universal stirrer with dynamic axial and radial flow also improves the ice formation rate.
The second phase of the research comprised of designing a pilot plant model for the wastewater purification plant for a production rate of 10 kg ice per hour. Based on the experimental learning, an energy efficient process flow for the plant was created by utilizing the cold energy from brine concentrate and pure water for precooling purpose and the total power consumption of the plant was estimated. Lastly, the crystallizer and separator for the DCF based plant were modeled and assemble into the pilot plant layout including secondary mechanical components such as pumps, compressor, heat exchangers and piping.
The second phase of the research comprised of designing a pilot plant model for the wastewater purification plant for a production rate of 10 kg ice per hour. Based on the experimental learning, an energy efficient process flow for the plant was created by utilizing the cold energy from brine concentrate and pure water for precooling purpose and the total power consumption of the plant was estimated. Lastly, the crystallizer and separator for the DCF based plant were modeled and assemble into the pilot plant layout including secondary mechanical components such as pumps, compressor, heat exchangers and piping.