A Case Study of Using the Strengite Process to Precommissioning Clean Two Closed Loop Systems at Astra Zeneca Macclesfield
Precommission cleaning of closed loop systems is necessary to insure short and long term smooth system operation. Failure to correctly clean systems can lead to fouling of heat exchange surfaces, poor valve operation, higher energy costs, and a wide range of other problems. Good precommissioning cleaning should remove debris, oils/greases, corrosion films such as rust, and mill scale created during pipe formation. The standard method for precommission cleaning of closed loop systems is to introduce a cleaner and circulate for a period of time. This solubilises oils/greases and strips any corrosion/mill scale from the pipework. The resulting solution is then flushed to drain using a continuous fill and drain method. Typically at least ten times the system volume is flushed to drain to complete the removal of the released contaminants. The process of cleaning causes metal ions such as copper, lead (from solders), and zinc to be dissolved, and transferred to the waste water. The discharge limit for copper and zinc is normally only 3 ppm. The process of cleaning closed loop systems virtually always breaks discharge regulations by many times over. It is not unusual for closed loop cleaning to create dissolved metal levels of over 1000 ppm. Closed loop cleaning is the largest source of toxic heavy metals to the sewage system. Alternative closed loop cleaning methods that do not create discharge rely solely on water velocity and filtration to remove corrosion films/deposits. They do not use chemical cleaners to clean pipe work surfaces. These methods are incapable of removing any corrosion or mill scale from pipework. This often leads to problems when systems become operational.
A Challenging Cleaning Requirement
Astra Zenica at Macclesfield installed an extension to their syringe filling line. This required extending both the chilled water and the low temperature hot water systems. The production area lacked a flushing water supply or a flushing drain. Additionally a cleaning process that could be operated without mess or disruption was required. The systems needed to be cleaned to a high specfication. All corrosion products, mill scale, oils and greases needed to be removed. The combined volume of both systems was between 2000 to 3000 litres. Cleaning the system using any of the standard or alternative closed loop cleaning methods would have been either impossible, or would have failed to clean the system sufficiently.
The Strengite Process: High Quality Closed Loop Cleaning Without Discharge
The extensions to the chilled and heating systems were connected together and cleaned as one system. The Strengite Process was used to clean the combined water system as it could deliver a high quality precommissioning clean that removed corrosion deposits, mill scale, oils and greases without discharge. Strengite C5 cleaner was introduced to the system and circulated for several days for cleaning action to occur. After this, the Strengite equipment was set up on a side stream to the system. Strengite’s Pink Purity product was then injected within the Strengite equipment to cause dissolved contaminants such as iron and copper to come out of solution. These were then directly removed by simple filtration within the Strengite equipment. Multiple water passes were made through the Strengite equipment with a further precipitation polishing product added to aid removal of fine contaminant particles. The system water was then pH adjusted to 7.6. A specially designed corrosion inhibitor product which builds upon the ions that remain in solution at the end of the Strengite cleaning was then added. Final water samples taken 10 days after the clean had iron levels of 1.8 ppm ppm total iron and 0.7 ppm soluble iron. The copper levels were <0.2 ppm total and <0.2 ppm soluble copper. Throughout the entire Strengite cleaning process there was no consumption or discharge of water. In total 20,000 to 30,000 litres of water supply and pollution was avoided.
Soluble metals become insoluble and are removed on filter bags.
The Strengite Process offers a more sustainable way to clean closed loop systems without water consumption or pollution. The Strengite Process is a patented process. The technology, equipment and products for the Strengite Process are only available to licenced and trained water treatment specialists who operate to a high standard and skill level.
Strengite equipment used to clean the system.