Operation of a horizontal tube brine concentrator

Abstract

An apparatus to concentrate solutions was developed and described in this paper. In the development advantage was taken of all know-how accumulated during the development of sea water evaporators and the development of techniques to treat sea water and product water. The purpose of the developed concentrator is to concentrate effluents from inland power plants cooling towers, industry cooling towers, industrial waste water and other solutions. A pilot plant at the Research Center in Tel-Baruch, near Tel Aviv has been operated since the middle of 1977. The plant is a single effect concentrator coupled to a condenser, with a capacity of up to 400 kg vapour per hour. The prevention of scale (CaSO 4, CaCO 3 or other constitutents) has been carried out by combined techniques of seeding process plus a threshold treat- ment. Two series of runs were conducted in this period. During the first half of the period the plant operated with sea water feed. The unit ran continuously (excluding weekends) for 1100 hours during which the internals, including heat transfer tubes remained clean as at startup. This was also demonstrated by the steady thermal conditions of the plant. This run demonstrated the ability of the process to overcome the tough problem of CaSO 4 scaling. In the second half of this period tap water was fed into the concentrator since there is no possibility to catch industrial effluents in Tel Baruch. Startup was done without cleaning of the heat transfer surfaces after the previous run with sea water. The unit ran continuously for 1500 hours with the same success in keeping performance steady as before. It is to be noted that the concentration of clean tap water is more complicated than the concentration of an effluent in which the suspended solids and other non-mineral constituents may assist in performance of self-seeding. It is believed that the process developed may lead to the achievement of “the zero discharge concept” for waste water treatment. The immediate applications of this process are: 1. Concentrating blow-downs from power plants and industrial cooling towers, as well as brines from membrane processes. 2. Industrial waste water ultimate disposal which combine chemical recycling and high quality water rennovation. 3. Concentrators for the food, canning and pharmaceutical industry.