remained effective. Within a week, both inlet and outlet TSS returned to non-detectable levels. The use of media spacers – despite reducing overall media volume – was shown to improve filter effectiveness by preventing pleat collapse and maintaining available media area, supporting longer run life (see Table 3 ). Run B2 was not included due to a system upset. The comparison of the double spacer element configurations to the single spacer element configurations clearly illustrated the benefit of the double spacer design in increasing available media.
Analysis of the effect of media grades on removal efficiency
Sample #
Inlet (mg/L)
Outlet (mg/L)
Novalite X
Novalite Y
removal removal efficiency (%) efficiency (%)
3,4 5,6 7,8
1.3 8.0
0.5 1.1 0.7 0.3 ND 1.1 ND
62% 86% 94%
11.2
9,10
0.9 1.0 8.0 ND
67%
11,12 13,14 15,16
80-100%¹
94%
50-100%¹
Average efficiency (from average effluent and influent over the available samples)
89%
84-97%¹
1. Removal efficiencies provided as a range when effluent samples are 'non-detectable'. The lower efficiency corresponds to our use of the calculated effluent concentration, and the upper from the ND reporting.
Table 4
Choice of media grade Evaluation of Novalite Grade X and Grade Y, along with their removal efficiencies, is shown in Table 4 , derived from the gravimetric analysis. From Table 4, Grade Y media with double spacers had an average run life of 253 hours compared to 161 hours for Grade X. In the context of removal efficiencies (84% vs 89%, as shown in Table 5 ), it appears that Grade Y offers better value. However, note that during an upset condition and its immediate aftermath, the Grade X elements allow for better removal of contaminants, thereby preventing settling in
dead spots, which traditionally leads to future process upsets. Effect of differential pressure on efficiency The Transcend Solutions elements were designed to be operated at higher differential pressure. In addition, the differential pressure occasionally fluctuated during the run life of all the Novalite elements. It was unclear whether the differential pressure fluctuations were caused by some other equipment or liquid level fluctuations. Regardless, the results are shown in Table 5. The data are plotted in Figure 4 using the lower measured values of efficiency. Figure 4 illustrates that removal efficiencies tended to
Effect of differential pressure on removal efficiency
Sample #
Inlet
Outlet (mg/l)
DP
Removal efficiency
(mg/l)
100
3,4 5,6 7,8
1.3 8.0
0.5 1.1 0.7 0.3 ND 1.1 ND
5
62% 86% 94% 67%
30 40 10 20 50 60 70 80 90
25 30 18
11.2
9,10
0.9 1.0 8.0
11,12 13,14 15,16
6
80-100%¹
30 15
94%
N
50-100%¹
1. Efficiencies provided as a range when effluent samples are 'non-detectable'. The lower efficiency corresponds to our use of the calculated effluent concentration, and the upper from the ND reporting.
0
0
5
10
15
20
25
30
35
Di erential pressure (psid)
Figure 4 Effect of differential pressure on TSS measured removal efficiency
Table 5
Refining India
63
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