Arrays 2-stage array with 3 pressure

Figure 5.1 Two-by-one (2 1), 2-stage array with 2 pressure vessels in the first stage and 1 pressure vessel in the second stage.

The PRO and BRO unit recovery was 75% and 50%, respectively, and the overall recovery was 87.5% with the BRO feed (PRO reject) composition as TDS = 1300 ppm, hardness = 825 ppm, 504 = 360 ppm, and sihca=16ppm. The BRO unit was a one-stage array with three pressure vessels (3 0) in parallel and three elements per pressure vessel (9 elements total). The RO elements were Hydranautics ESPAl (40 cm dia.). 

A typical RO skid is shown in Figure 2.25. It is a single-pass, two-stage (4 2 array) unit with pressure vessels containing six spiral wound membrane elements (20 cm X 100 cm) in series in each vessel. There is room on the backside of the skid to double the number of vessels to make it into an 8 4 array with permeate flow rates approaching 70 m /h at 75%. The RO high-pressure pump is multi-stage, horizontal, submersible type. The skid... 

The recovery of the BRO unit increased from 50% to 70% when a small portion (<20%) of the BRO reject stream was recycled to the BRO unit inlet, as shown in Figure 3.40 [69]. Reject recycle provides additional fluid flow above the membrane, thereby reducing concentration polarisation and achieving higher flow. Thus, the overall water recovery was 92.5%. The BRO unit was a two-stage, 3 2 parallel pressure vessel array with three elements per pressure vessel (15 elements total). The RO elements were Hydranautics ESPA2+ (20 cm dia.). The average flux was 17—20 Imh. 

The UF unit is designed for a flow rate of 45 m /h with a flux of 21.6 Imh (27.8 Imh max). The membrane TMP is 15 mbar with the mean permeability 1500 Imh/bar at 20°C. The MBR operating cycle is 8 m on /2 m relaxation. CIP is with NaOCl (6 g/1 solution) annually. The UF permeate is pumped to the RO system at 20—25°C. The RO unit is a three-stage (4 2 1) array with six elements per pressure vessel. The RO elements are spiral-wound 20 cm diameter (Toray SU-720). The membranes are brackish water polyamide membrane thin-fikn composite. The feed pressure is 11—14 bar g and the product water recovery is 85%. The RO permeate is poHshed by mixed-bed ion-exchange to provide boiler feed water. The plant meets the effluent concentration limits COD <51 mg/1, (>97% removal), undetectable TSS and <5 mg/1 Total nitrogen. 

It is interesting to consider the results of the molecular dynamics simulation showing that the reaction occurs in two stages that could well correspond to the formation of the transparent yellow and to the brownish products. As a whole, the calculations indicate that the final product is a bent polycarbonyl chain with five-membered rings attached and with interconnection between the various chains in a quasi-two-dimensional array. Such a rather extended array is not much different from the suggested structure of the polymer obtained from furan at high pressure [303, 338]. In the molecular dynamics simulation the formation of carbon dioxide molecules is not observed in agreement with the experimental result that CO2 formation only occurs upon intense laser irradiation. 

Focusing on spiral wound membrane modules as the most common type of membrane modules used in industry today, an RO array or "skid" or "train" consists of a number of pressure vessels arranged in specific patterns. Figure 5.1 shows an array of 3 pressure vessels. The pressure vessels are arranged into 2 sets, with 2 pressure vessels in parallel followed by 1 single pressure vessel. The 2 sets of pressure vessels are in series. Each set of pressure vessels in parallel (even if there is only 1 vessel) is called a STAGE. 

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