High-pressure reverse osmosis modules

FIG. 22-50 Cutaway view of high-pressure hollow-fine-fiber reverse-osmosis module. Courtesy DuPont.)... 

Fig. 23. Two types of hollow-fiber modules used for gas separation, reverse osmosis, and ultrafiltration applications, (a) Shell-side feed modules are generally used for high pressure appHcations up to - 7 MPa (1000 psig). Fouling on the feed side of the membrane can be a problem with this design, and pretreatment of the feed stream to remove particulates is required, (b) Bore-side feed modules are generally used for medium pressure feed streams up to - 1 MPa (150 psig), where good flow control to minimise fouling and concentration polarization on the feed side of the membrane is desired.

Figure 3.42 Exploded view and cross-section drawings of a spiral-wound module. Feed solution passes across the membrane surface. A portion passes through the membrane and enters the membrane envelope where it spirals inward to the central perforated collection pipe. One solution enters the module (the feed) and two solutions leave (the residue and the permeate). Spiral-wound modules are the most common module design for reverse osmosis and ultrafiltration as well as for high-pressure gas separation applications in the natural gas industry...

Figure 5.24 Flow schematic of a typical brackish water reverse osmosis plant. The plant contains seven pressure vessels each containing six membrane modules. The pressure vessels are in a Christmas tree array to maintain a high feed velocity through the modules...

The reverse osmosis plant is formed by three blocks of Toray polyamide membranes rolled in spiral, each 7.5 m long, 2.4 m wide, and 2.35 m high. Each block contains two filtering stages the first composed of eight membrane modules that work at 15 bar and the second composed of five membrane modules at 23 bar. In total, there are 13 pressure tubes, each formed of six membrane units. 

Membrane installation, capacity of 1 mVh pure permeate, was composed of three stages of RO (Figure 25.3) preceded by pretreatment with polypropylene (PP) depth filters. The first two stages were used for purification, the third one for final concentration. Two types of spiral-wound reverse osmosis (SWRO) modules were used in the installation SU-720R and SU-810 (TORAY). Both types of modules worked under a pressure of 20 bar and with high salt... 

In addition, the ability to work in a wide range of operative conditions is another key aspect for the development of advanced membranes. Chemical stability is of particular importance when the membrane interfaces are exposed to aggressive solvents, such as in several organic solvent nanofiltration (OSN) applications [21]. Resistance to fouling is also important in water filtration because this phenomenon can threaten the continuous operability of the membrane module [22]. In high-temperature (eg, precombustion CO2 capture from syngas [23] or polymer electrolyte membranes for fuel cells [24]) and high-pressure (eg, reverse osmosis and nanofiltration membranes for... 

Reverse Osmosis Membrane modules must be replaced periodically and high-pressure pumps require maintenance. Operation must be dosely monitored. 

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