Original equipment experienced reliability issues, resulting in downtime and maintenance costs.
by Jayant Patil
September 20, 2019

One of the largest wastewater plants in the world to use reverse osmosis technology for wastewater reclamation, a wastewater treatment and reclamation plant in Kuwait is critical to the country’s industry, agriculture and people. The Kuwaiti plant produces reclaimed water that accounts for approximately 60 percent of the country’s domestic wastewater and 20 percent of its overall water needs.

When the facility began experiencing maintenance issues and unplanned downtime on grit pumps due to mechanical seal leakages, an analysis was required to discover the root cause. The inspection included a comprehensive diagnostic check of the facility’s equipment. Experts determined that the problem was with the improperly designed mechanical seal installed during commissioning. Although the plant practiced external flushing, the slurry seal design did not perform as was needed, causing disturbance to the process and requiring costly repairs in the first two to three months of usage. The slurry seal had to be replaced every six months.

The team of application engineers also considered existing corrosion on the shaft sleeve and dimensional considerations to be addressed for corrections to last long term.

The team was searching for a more cost-effective solution that would save the plant maintenance costs and downtime. So, the plant decided not to use another standard slurry seal as a replacement. Instead, it replaced the faulty slurry seal with a single-cartridge slurry seal design.

Meant to hold up to the heavy volume and abrasive slurry challenges present at the Kuwaiti facility, the single-cartridge slurry seal had performed well in other sludge clarification and treatment facilities. It can be used on process pumps and other rotating equipment and contains primary and secondary seal face materials. The seal also features nonclogging, elastomer-encased cone springs designed to apply constant spring load in the seals. This feature is meant to eliminate dynamic O-rings. The seal operates without flush or water quenches, which allows it to work well in general-purpose, low-maintenance applications.

The plant also upgraded the shaft sleeve, and with the new seal design, the end user has seen satisfactory results. It has now been 67 months since the upgrade, and the equipment is running without leaks. This saved the facility approximately $313,000 during that time period.

A senior project engineer at the wastewater treatment and reclamation plant said he would like to carry out similar upgrades, “which will deliver significant cost-savings and performance benefits for the plant.”