Desalination Maintenance

Other plant-scale applications to pollution control include the flotation of suspended sewage particles by depressurizing so as to release dissolved air [Jenkins, Scherfig, and Eckhoff, Applications of Adsorptive Bubble Separation Techniques to Wastewater Treatment, in Lemlich (ed.). Adsorptive Bubble Separation Techniques, Academic, New York, 1972, chap. 14 and Richter, Internat. Chem. Eng, 16,614 (1976)]. Dissolved-air flotation is also employed in treating waste-water from pulp and paper mills [Coertze, Prog. Water TechnoL, 10, 449(1978) and Severeid, TAPPl 62(2), 61, 1979]. In addition, there is the flotation, with electrolytically released bubbles [Chambers and Cottrell, Chem. Eng, 83(16), 95 (1976)], of oily iron dust [Ellwood, Chem. Eng, 75(16), 82 (1968)] and of a variety of wastes from surface-treatment processes at the maintenance and overhaul base of an airline [Roth and Ferguson, Desalination, 23, 49 (1977)]. 

For this reason, two pass seawater desalination process have been necessarily employed till quite recently, and the results obtained have been satisfactory to some extent with regard to water quality and practical operation. However, one pass process has advantages over two pass process for simple and compact plant, simple operation, easy maintenance and lower energy consumption. 

Compliance with proper operational procedures and following a careful maintenance program can also reduce desalination costs by minimizing the replacement of damaged membranes, reducing the use of cleaning chemicals, and reducing the... 

Pervov, A.G. et al., RO and NF membrane systems for drinking water production and their maintenance techniques. Desalination, 132, 315, 2000. 

Small-scale reactors have more advantages than large-scale reactors in variety of energy utilization, construction, maintenance and adoption of innovative technologies, while the latter have scale merits in construction cost. The nuclear energy utilization of small-scale reactors are ship propulsion, electricity generation, heat supply, and sea water desalination, etc. Construction and maintenance for small-scale reactors can be made in factories exclusive use for them, but not at the site of the plant. In small-scale reactors, the safety can be enhanced sometimes by new technologies. 

Characterization of uncertainties in the operation and economies of the proposed seawater desalination plant in the Gaza Strip was made by using a Bayesian belief network (BBN) approach [80]. In particular, the model was used to (1) characterize the different uncertainties involved in the RO process, (2) optimize the RO process reliability and cost, and (3) study how uncertainty in unit capital cost, unit operation and maintenance (O M) cost, and permeate quality was related to different input variables. The minimum specific capital cost was found to be 0.224 0.064 US /m, and the minimum O M cost was found to be 0.59 0.11 US /m. This unit cost was for a production capacity of 140,000 mVday. 

To justify the assumptions, the estimated cost in power consumption, labor, and membrane replacement was compared with that in a seawater reverse osmosis desalination (SWRO) plant (Atikol et al., 2005). For SWRO, the reported cost for power was 0.04 US m, we estimated 0.022 US m for our system. The lower cost in energy consumption is mainly due to the low operating pressure and significantly higher water recovery in this system. The cost for pre-treatment was assumed to be lower than seawater plant due to the significantly much better water quality in the drinking water sources. The maintenance cost was adopted from the... 

Let s consider a simplified example. Assume you inherit a desalinator. You produce 100,000 gal/day, which you sell at 12. per 1,000 gal. Your electric bill to run the desalinator is 13,500/month. The cost of labor to run the desalinator is 10.50/hour. The cost of space at the local pier is 2,4(X) per month. In this idealized example we will neglect all other costs, such as maintenance. We will also assume the desalinator is operating 24 hours a day, 52 weeks/year. We now calculate the profit (or loss). For the revenue we have... 

Table 3.8 compares the estimated costs of potable water production through seawater desalination cogeneration with conventional and VHTR power plants (Sato et al., 2014). The conventional plant is based on a modem gas turbine combined cycle (GTCC) power plant at 55% power generation efficiency. The VHTR cogeneration system is that described in Section 3.4.2.2. The costs were evaluated by an original equipment manufacturer (OEM) vendor active in the Middle East desalination plant constmction. The vendor carried out the plant equipment design and evaluated the required operation and maintenance. The cost estimation was then developed based on the vendor construction and operation know-how of comparable-scale MSF plants. 

In service, transient, and shutdown conditions—maintenance procedures Care has to be taken of the possible change of conditions during shutdown and/or transient periods, which are not necessarily less prone to the development of crevice corrosion. An example is the case of desalination plants where concentrated chloride solutions may become very dangerous... 

Seawater desalination by reverse osmosis is the most effective method for the production of freshwater among various desalination technologies. HoUow-fiber RO membranes and flat-sheet membranes have been developed for brackish water and seawater desahnation by a two-pass process since 1976 (Ohya, 1976). In spite of a satisfactory result of two-pass seawater desalination processes, the one-pass process has the advantages of simple and compact plant, simple operation, easy maintenance, and the lowest energy consumption. Although several one-pass seawater desalination systems by reverse osmosis have been... 

This provides mechanical stability to the fiber array in the RO element. The fibers at one end of the element are precisely cut so that product water can be discharged from the bore of the fibers. Toyobo RO modules for seawater desalination have configurations in the doubleelement type as shown above. Because the permeate water of each element in a pressure vessel can be obtained directly, the quality of each permeate water can also be measured directly. This feamre allows easier maintenance of an RO plant (Kannari, 1995). 

Key Operating and maintenance (Q M) cost elements for the Ashkelon SWRO project are shown in Table 3.7 (Velter, 2004). The difference between the first 5 years is attributed to the use of new equipment at the first years of the plant operations and used equipment after that time. An O M cost breakdown based on experience with seawater desalination in Spain is shown in Figure 3.22 (Medina, 2004). 

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