System for Energy Recovery and Reduction of Deposits on the Membrane Surfaces in (Variable Power and Variable Production) Reverse Osmosis Desalination Systems

Abstract

A method and a device for desalination, that operates with reverse osmosis membranes (7) and pressure vessels (9) and (20) that are connected to the high pressure circuit via valves (17) and with the low pressure circuit via valves (10). The proposed system includes the operation of a water intake pump (2) and high pressure pump (5) and a circulating pump, when vessel (9) is connected to the high pressure circuit, vessel (20) is fed with fresh salty water in the low pressure, next vessel (20) is connected to the high pressure, vessel (9) is disconnected, then vessel (9) is rinsed, vessel (9) becomes complete with salty water in the low pressure, then vessel (9) is connected in the high pressure, next vessel (20) disconnected, vessel (20) is rinsed, vessel (20) becomes complete with fresh salty water in the low pressure. The process is repeated with alternation of vessels (9) and (20). The proposed method doesn't have loses due to the exchange of the medium, as in other energy recovery systems, such as turbines or other pumps having efficiency smaller than one. In addition the circulation speed and flow is increased. Because of the high circulation and flow the concentration polarization is reduced. Which means that the effect of local increase in the concentration, near the surface of the membrane, is reduced and therefore the efficiency of the membranes is improved and the deposits decrease. Additional optimizing can be accomplished: a) with the use of a mechanism based on the Bernoulli's Principle under conditions of pressure so as to avoid the use of a high pressure circulator with ultimate goal the reduction of cost and b) by using a centrifugal separator for the removal of solids and part of the organisms that exist in the water, before entering the membranes, so as to avoid the chemical processing of the water before entering the membranes and to avoid deposits on the membranes. The application of our method and system to units having varying power supply or varying water production (powered by renewable energy sources) and in applications where there are high concentrations of dissolved substances and therefore required higher pressures to overcome the osmotic pressure, such as the desalination of sea water, processing of organic dilutions and waste water processing.

Dependencies are inferred from the claim text.