inlet – intended to eliminate the need for post-carbon filtration. However, the carbon bed had been offline for more than a year, further reducing contamination control effectiveness. Overall, poor filtration practices, bypassing of filters, and infrequent or neglected filter replacements in various parts of the system contributed to rapid filter plugging, limited filter life, and elevated maintenance costs, prompting the refinery to consult Transcend Solutions for remediation and optimisation. Analytical technique The plant attempted to assess filter performance by measuring total suspended
Figure 2 Photo of two high-pressure membrane sample holders. The holder on the left is opened, showing the inside of the filter housing with the membrane support screen (bottom left). The holder in the middle is assembled and ready to use in sampling. The Teflon-tape- wrapped fitting shown on the right is prepared to be attached to a process sample port with a high-pressure, braided hose attached to direct process fluid flow from the sample port to the filter housing inlet. Flow control valves are not shown
solids (TSS) using bottle samples. However, the results were inconclusive – effluent TSS appeared higher than influent. This discrepancy arose due to the reactivity of dissolved hydrogen sulphide and iron with air during sampling and analysis, which caused artefact formation. To address this, an online TSS measurement method was developed that avoids air exposure and preserves sample integrity (see Figure 2 ). This approach uses a high-pressure gravimetric kit with a pre-weighed membrane housed in a pressurised holder. Sampling ports are purged before connecting the kit to eliminate dead- zone contaminants. Once connected, valves are sequentially opened to allow a defined volume of fluid to pass through the membrane. After sampling, the system is flushed to prevent ex- situ reactions, and the membrane is sent to the Transcend Solutions IDEA Labs for analysis. In the lab, the membrane is rinsed with appropriate solvents (for example, water, acetone, or hexane), dried, and reweighed. The gravimetric TSS concentration is calculated from the weight gain per volume filtered. Additionally, photomicrographic analysis is performed to
The quench water, recirculated at 1,800 gal/ min, used slip-stream filtration with cotton string-wound filters. Similarly, lean and recovered amine streams were filtered using outdated cotton filters that had not been replaced for an unknown duration. A full-flow rich amine filter housing was installed 16 months prior, equipped with 21 cellulose-based 10-micron 'absolute' rated elements (see Figure 1 ). However, the system lacked a standby filter, and filtration had to be shut down for two to four hours during element replacement. Initially, plant operators left the rich filter bypass valve partially open during operation, undermining filtration. After this protocol was eliminated, the filter run life averaged just 28 hours over five months, resulting in 120 element replacements in 153 days. A broader two-year analysis (excluding bypass periods) showed an average filter life of 34 hours. The plant design included a loop that allowed a portion of rich amine effluent to circulate through a carbon bed and back to the rich filter
Refining India
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