Cool Steam Method for Desalinating Seawater

Abstract

Cool steam is an innovative distillation technology based on low-temperature thermal distillation (LTTD), which allows obtaining fresh water from non-safe water sources with substantially low energy consumption. LTTD consists of distilling at low temperatures by lowering the working pressure and making the most of low-grade heat sources (either natural or artificial) to evaporate water and then condensate it at a cooler heat sink. To perform the process, an external heat source is needed that provides the latent heat of evaporation and a temperature gradient to maintain the distillation cycle. Depending on the available temperature gradient, several stages can be implemented, leading to a multi-stage device. The cool steam device can thus be single or multi-stage, being raw water fed to every stage from the top and evaporated in contact with the warmer surface within the said stage. Acting as a heat carrier, the water vapor travels to the cooler surface and condensates in contact with it. The latent heat of condensation is then conducted through the conductive wall to the next stage. Net heat flux is then established from the heat source until the heat sink, allowing distilling water inside every parallel stage.

Mathematical Analysis of Sub-Atmospheric Vapor Pipeline (SAVP) Transmission for Seawater Desalination

“…However, the limited rate of freshwater transfer and the need for natural warm and cold sources for implementation are obvious limitations of the SAVP method; however, this method has several benefits and advantages in terms of industrial efficiency indices and economic criteria. Drastic reduction or even elimination of energy consumption, advantages such as seawater desalination with minimal energy input by eliminating the heat source and mechanical devices, the drastic reduction of energy consumption (or elimination) in the process of water transfer, the possibility of re-access to energy at destination through the use of a water turbine and finally utilizing the benefits of the Paris Convention for the advantage of not producing carbon dioxide make the SAVP desalination highly efficient and preferred over other methods [1,2]. In another invention called "desalination towers", which is significantly different from other available methods, hot air, after being blown and mixed with seawater, turns it into a two-phase evaporating fluid and stimulates it to go up a tower called the desalination tower [3,4].…”

Low-Temperature Vacuum Evaporation of Ammonia from Pig Slurry at Laboratory and Pilot-Plant Scale

“…Water vapour acts as a heat carrier, travels to the cooler surface and condensates in contact with it. This novel method avoids continuous vacuum application by using switches and solenoid valves to maintain the whole system's tightness under strict sealing conditions [18]. The recovered ammonia can be in the form of, among others, an ammonium sulphate or nitrate solution, depending on the absorption acid.…”