1、外文资料Seawater desalination by reverse osmosis (case study)M. Abou Rayana*, I. Khaledb“Mansoura University, Mansoura, EgyptTel. +20 (3) 5920641; Fax +203 5920641; email: mrayaDesalination Sector Sinai Development Organization South Sinai, EgyptReceived 9 ApriI 2002; accepted 16 April 2002AbstractThis
2、paper presents a case study of the operation and maintenance of 2000 m3/d desalination plant erected in 1995. The results have been obtained over 6 years of operation. The plant consists of four units with a capacity 500 m3/d each. The results obtained are used to evaluate and develop the optimum pl
3、ant operating pressure and temperature. The daily feed salinity, temperature and pressure were recorded, and finally the tota cost for product of potabIe water was calculated. Recommendations were issued regarding the optimum operating conditions and the most pertinent operating problems. A technoec
4、onomical analysis is undertaken in order to evaluate the cost of the water produced and technical reliability of the technology. The objective is to present field results of the reverse osmoses plant operation in order to evaluate the reliability of this technology in comparison with other technolog
5、ies.Keywords: Seawater desalination; Reverse osmosis; Economic evaluation1. IntroductionThe present study gives an outline description of a reverse osmosis (RO) technology. The considered plant has been constructed on the site of Dahab city in south of Sinai, Egypt. The required electrical power for
6、 the plants is supplied to the site from 8 generators, 500 KVA each.The saline water is supplied from 8 beachwells on the beach of the Aquaba gulf. The salinity of feed seawater is in the order of 44,000 ppm. The station consists of 4 units; each unit plant has maximum capacity of 500 m3/d. The plan
7、t started production in November 1995. The objectives of this study are: (l) The analysis of the performance in order to evaluate the determining operating factors.(2) The evaluation of the reverse osmosis efftciency under the actual operating conditions.(3) The determination of the optimum operatin
8、g parameters.(4) The evaluation ofthe overall system reliability for long-term automatic operation.(5) The evaluation of the operation since 1995 to 2002 in order to explore the necessary maintenance work and the reliability of the technology.(6) The establishment of the best maintenance procedure f
9、or the membrane system.The plant is still working under continuous operation without any significant operational problems.2. General plant overviewThe plant consists of 4 units. Each 500 m3/dunit consists of1) Intake2) Multi media filters3) Cartridge filters4) Chemical system5) RO unit2.1. IntakeThe
10、 intake is a beachwell system. The RO unit requires 75 m3/h flowrate of raw seawater for one unit producing 500 m3/d. Based on the permeability of the soil, one beachwell can deliver a discharge of 75 m3/h. Safety margins and standby requirements for only 50% capacity are considered:(l) For one 500
11、m3/d unit 2 wells are required.(2) For four 500 m3/d units 8 wells are required.The beachwells are constructed according to the standard. The wells is equipped with submersible pumps. The following specification are applied: mechanical digging with a 10-inch diameter and depth of about 15 m. Applyin
12、g bentonite and taking various samples, each 1 m length to determine the quality of penetrating subsoil, the thickness and quality of water layer in order to assure the best design to the well casing. There are 10 -inch diameter PVC pipes The well flushing and cleaning is done via high pressure pump
13、s. The pump is a multistage submersible motor pumping set suitable for water application, particularly resistant to erosion and saline water, with the following characteristics:l The nominal discharge at due point 75 m3/hl The suction from the well improves water quality, particularly regarding fine
14、 surrounding materials. The sand is acting as a natural filter.2.2.1. Seawater chlorination systemThe seawater chlorination system is a complete automatically as well as manually actuated sodium hypochlorine solution dosing plant. The proposed plant comprises the following:a) PE solution tanks: Chem
15、ically resistant PE transparent cylindrical tank of 500 bit capacity. The tank is equipped with a seawater level gauge, drain valve and top cover. The post-chlorination is particularly important in order to disinfect the water introduced to the potable water network.b) Electrically activated agitato
16、r with stainless steel shaft and mixing blades mounted vertically. A small electric motor of fraction of horse power was used. The pump capacity is 27 L/h.2.2.2. DischargeThe outfall system includes one buried PVC pipe from the plant up to the seashore. The remaining part from the pipe (offshore pipes) is high-density PE laid down on the seabed with special covering. At the end of the outfall pipe a dis
