Seawater is pumped into the system via a seawater pump to a condenser. The performance and capital cost of the system are proportional to the number of effects contained in a unit. In the plate channels of an effect, the seawater on one side is heated up and partially evaporated to distillate vapour, which is used in the next effect on the other side, the distillate vapour from the previous effect is condensed, giving up its latent heat, into pure distillate.īy maintaining a partial pressure difference across the effects, the process is able to yield maximum efficiency from available low-grade thermal energy sources. Each effect is fitted with heat transfer surfaces based on patented Alfa Laval plates.
ENERGY BALANCE EVAPORATOR SERIES
The Alfa Laval MEP desalination process consists of a series of evaporation and condensation chambers known as effects. The fact that this system requires less power, and better facilitates the switch to LNG, also means it can make vessels significantly more environmentally friendly. As more ship owners look to make the shift to LNG due to emissions regulations, MEP is the ideal solution to further reduce costs. This technology works exceptionally well LNG fuelled ships, as they will typically have more excess heat available, and MEP works on waste heat recovery. This enables the production of much higher volumes of fresh water than other desalination technologies. Its lightweight, space-saving design takes up less floor space while offering much higher thermal efficiency in relation to its volume and weight compared to other evaporators. Straightforward operation and automated control provide maximum uptime at less cost compared to technologies such as reverse osmosis (RO) and multi-stage flash (MSF). Corrosion-resistant titanium heat transfer surfaces and non-coated materials withstand seawater and brines. A continuous thin film of water over the entire plate surface also minimizes the risk of deposit build-up (scale) and thereby downtime. Compared to traditional shell and tube technology, the Plate Technology gives higher thermal efficiency. All plates are identical with two gasket configurations being utilised in order to form both a condensing and an evaporating plate channel.
The thermal energy required to heat the inlet gas, the energy used for water evaporation in the BCE and the energy conserved from water vapor condensation were estimated in an overall energy balance analysis. The BCE method, as one of the most simple and accurate techniques, offers a novel way to determine Δ H vap values of salt solutions based on its energy balance equation, which had error less than 3%. Also, the experimental and theoretical techniques used for determining Δ H vap values of salt solutions were reviewed for the operation conditions and their accuracies compared to the literature data. Based on the analysis of derivation and Δ H vap values comparison, it is demonstrated that the original balance equation has high accuracy and precision, within 2% over 19-55 ☌ using improved systems. In this paper, the originally derived energy balance was reviewed on the basis of its physics in the BCE process and compared with new proposed energy balance equations in terms of obtained the enthalpy of vaporization (Δ H vap) values of salt solutions from BCE experiments. More importantly, it opened a new field for the thermodynamics study in the form of heat and vapor transfer in the bubbles. The energy balance and utilization involved in each BCE process form the fundamental theory of these applications. The heat supplied from warm/hot dry bubbles is to vaporize the water in various salt solutions until the solution temperature reaches steady state, which was derived into the energy balance of the BCE. Bubble column evaporator (BCE) systems have been studied and developed for many applications, such as thermal desalination, sterilization, evaporative cooling and controlled precipitation.