System design configurations RO system design LPT 2016
System design - configuration Topic 1. Standard system configurations Topic 2. Seawater system configurations Topic 4. Something you should know using LewaPlus Topic 5. Summary 2
System design - configuration Topic 1. Standard system configurations Topic 2. Seawater system configurations Topic 4. Something you should know using LewaPlus Topic 5. Summary 3
Various configurations are possible to reach requested water quality like single and double pass Single pass Single pass system The water passed the RO membrane once Recovery rate : BW: 60-85% SW:40-55% Most common for RO processes In Seawater RO processes it is used if a Boron level above 0.4ppm is accepted Double pass The water passed the RO membrane twice Recovery rate in pass 2: up to 95% The concentrate of pass 2 is usually used for recirculation to pass 1 or pass 2. In Seawater RO process a split partial configuration is used to lower the size of pass 2. 4
Concentrate can be added to the feed or substitute some parts of it depending on the task Concentrate recirculation within a pass The concentrate is usually added to the feed flow to ensure the min. cross-flow velocity Concentrate recirculation from second pass to the first pass The concentrate of pass 2 is added to the feed flow of pass 1 to ensure the min. cross-flow velocity The concentrate of pass 2 substitute parts of the feed flow of pass 1 to dilute the feed to get a better permeate quality 5
Permeate blending and recirculation are seldom in single pass systems Permeate blending If lower permeate quality is required (approx.100ppm TDS) To decrease the element number by decreasing feed flow Permeate recirculation An option to adjust the permeate quality by the same arrangement in case that conditions are greatly changed (ex. 5-30 C) 6
Possibilities to compensate unbalanced flows in a system e.g. if the single element recovery rate is above 15% Permeate throttling Permeate pressure is settled to reduce the flux The reason is to diminish the flow unbalance at high average feed concentration (usually first stage) The capital costs for throttling are lower compare to the booster pump The operational costs may be higher since more pressure is needed Booster pump To diminish the flow unbalances at high average feed concentrations the pressure in the second stage is increased with a booster pump The pressure in stage one can be reduced to reach the same average permeate flux Less energy may be needed compare to throttling 7
System design - configuration Topic 1. Standard system configurations Topic 2. Seawater system configurations Topic 4. Something you should know using LewaPlus Topic 5. Summary 8
In 2 pass SW system permeate blending and spilt partial is common Conventional double pass in SW Split partial system Most of the permeate of pass 1 are treated in Pass 2. Depending on the water quality some permeate from pass 1 is used for blending. The low salinity permeate of the first elements in pass 1 is used for blending. Since this water quality is better compared to the conventional part more permeate for blending can be used. Therefore the size of pass 2 can be reduced. 9
In the Turbocharger the concentrate pressure moves a turbine which adds pressure to the feed Example: Turbocharger adds here 22 bar to the feed pressure Q f = 124 m 3 /hr P m = 48 bar Q f = 124 m 3 /hr P m = 70 bar Q f = 62 m 3 /hr P m = 67 bar Q f = 62 m 3 /hr P m = 0,3 bar Q f = 62 m 3 /hr P m = 0,5 bar Pressure and Flow rate influence the pressure boost P = T ef R cf (P c P e ) P pressure boost T ef turbocharger efficiency R cf ratio of concentrate to feed flow (or interstage flow) P c concentrate pressure at the RO unit exit P e concentrate pressure at the turbocharger exit 10
The isobaric device has no moving parts but the feed water is mixed with the concentrate to a certain extend Isobaric devices are very energy efficient 11
Hybrid System is combination of S - HR/HF with higher Permeate TDS but a lower energy consumption HR HR HR HF HF HF HF Calculated operational pressure: 62 bar 12
HR type as lead elements lead to lower lead elements flux and lower fouling Comparison of different hybrid configurations (S400HR x 7 + S400HF x 0) Permeate TDS [mg/l] 131 (S400HF x 7 + S400HR x 0) Permeate TDS [mg/l] 185 HR HR HR HR HR HR HR Pressure [bar] 60,3 HF HF HF HF HF HF HF Pressure [bar] 54,9 Lead El. Flux [lmh] 28,16 Lead El. Flux [lmh] 31,45 (S400HR x 6 + S400HF x 1) Permeate TDS [mg/l] 139 (S400HF x 6 + S400HR x 1) Permeate TDS [mg/l] 177 HR HR HR HR HR HR HF Pressure [bar] 59,4 HF HF HF HF HF HF HR Pressure [bar] 55,4 Lead El. Flux [lmh] 27,45 Lead El. Flux [lmh] 31,99 (S400HR x 5 + S400HF x 2) Permeate TDS [mg/l] 147 (S400HF x 5 + S400HR x 2) Permeate TDS [mg/l] 169 HR HR HR HR HR HF HF Pressure [bar] 58,5 HF HF HF HF HF HR HR Pressure [bar] 56 Lead El. Flux [lmh] 26,79 Lead El. Flux [lmh] 32,58 (S400HR x 4 + S400HF x 3) Permeate TDS [mg/l] 154 (S400HF x 4 + S400HR x 3) Permeate TDS [mg/l] 161 HR HR HR HR HF HF HF Pressure [bar] 57,7 HF HF HF HF HR HR HR Pressure [bar] 56,7 Lead El. Flux [lmh] 26,17 Lead El. Flux [lmh] 33,23 (S400HR x 3 + S400HF x 4) Permeate TDS [mg/l] 162 (S400HF x 3 + S400HR x 4) Permeate TDS [mg/l] 154 HR HR HR HF HF HF HF Pressure [bar] 56,9 HF HF HF HR HR HR HR Pressure [bar] 57,4 Lead El. Flux [lmh] 25,59 Lead El. Flux [lmh] 33,95 Product flow 4.5 m3/h, Recovery 45%, Feed TDS 32000 mg/l NaCl, Feed ph 8.2, Temperature 25 C, after 3 years 13
System design - configuration Topic 1. Standard system configurations Topic 2. Seawater system configurations Topic 4. Something you should know using LewaPlus Topic 5. Summary 14
Element deviation using different design software may be caused due to different calculation models Comparison of element simulations calculated by different software Check the definition of fouling in the program Are they using a fouling factor, flux decline ratio or the flux decline per year? Check whether the program does include the salt passage increase Can you change the age of the membrane? Pay attention on the temperature effect How is the temperature effect calculated? Action Set the fouling factor to 1,0 the flux decline/year to 0 Use the same salt passage increase of set the membrane age to 0 Adjust the temperature to standard conditions (25 C) 15
LewaPlus is more than just a design tool it offers direct support Use our product scout to get direct datasheets and MSDS on your computer Find explanations and definitions in our help function 16
System design - configuration Topic 1. Standard system configurations Topic 2. Seawater system configurations Topic 4. Something you should know using LewaPlus Topic 5. Summary 17
Why use LewaPlus for system design? The software offers you everything you need for system design It covers almost all RO design configurations More then 10.000 configurations are possible to optimize the system Optimization of the whole system is possible not only improvements of the RO part LewaPlus saves not only all your design projects it is also a library for data sheets You can easy compare different design and can transport it to Excle. 18
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