Vertical Heat Exchanger Cleaned In-Situ
Heat Transfer improves using remote tube cleaning system
INEOS is a leading European polyvinyl chloride manufacturer and is currently ranked fifth worldwide. The company’s activities are vertically integrated and include the manufacture of EDC (ethylene dichloride), VCM (vinyl chloride monomer – the monomer used to produce PVC) and PVC resins. Production capacity now stands at 1.4 million tonnes per annum of PVC resins, and 1.1 million tonnes per annum of VCM. INEOS contacted Tube Tech when a vertical condenser, handling a vinyl polymer on the tube side and water on the shell side, had become blocked.
A vertical cooling condenser handling a vinyl polymer on the tube side and hot water on the shell had become blocked. The problem was exacerbated by the process overfilling the condenser, which resulted in a large deposit of polymer on the lower tube face and blockages climbing to the top tube plate. The condenser has 295 tubes and the client believed that just 5% were blocked. When the tube plate was flooded by Tube Tech it was found that 10% were completely blocked from top to bottom and a further 5% suffered severe restrictions allowing only a slow drain away at the lower end of the bundle.
Traditional Local Contractors
In-situ cleaning at the traditional 1000-Bar water pressure was not effective nor was unblocking the condenser in situ with flexible ultra-high pressure (UHP) water jetting hoses as it was considered too dangerous. Using the usual site specific methods the condenser tube bundle would have to be lifted out from the heat exchanger shell, requiring two large cranes plus the ever present danger of damage to the bundle during the lift. It would then have had to be laid down horizontally to enable safe horizontal water-jetting using rigid lances, the usual practice
The Tube Tech Solution
Tube Tech were certain that the bundle could be cleaned in-situ and decided to use its semi-remote tube cleaning system the SafeDrill. The severity of the blockages necessitated round-the-clock working: the deposits had high impact polymer compound-like properties and were initially difficult to penetrate even with tube cleaning powers of SafeDrill, but the system rose to the challenge and the blocked tubes were cleaned back to bare metal. Where a passage down the tube was apparent it was safe to use Tube Tech’s remotely operated SafeFlex, for the cleaning, a system which prevents the jetting head exiting any tube in an uncontrolled and hazardous way whilst under pressure.
Tube Tech comment
“This job presented an interesting challenge for us as polymer from one plant to another differs in so many different ways and reacts differently when attacked with different cleaning systems. We were, however, convinced the bundle could be cleaned in situ. We knew from the client’s experience that ordinary high-pressure water could not clean the blocked or restricted condenser tubes satisfactorily and if left they would continue to seriously hinder production, plus it was perceived that it was too dangerous to use ultra-high pressure water with the condenser vertical. A low pressure, semi remote option had to be the answer, which is why we suggested to the client that we use our unique SafeDrill to unblock and remove the severe restrictions.” Scott Donson, Senior Technical Sales Engineer
“Since the clean we have been experiencing a heat transfer improvement of ~17% (taken off initial batches). That means we can run the process faster and catalyst levels have been increased on every batch since the clean which was conducted in a very controlled manner. We were attracted by the different method Tube Tech was proposing to use and were happy with the way the job went – the Tube Tech team worked well throughout the night and kept the Process Manager well informed regarding the blocked tubes and an estimated time for completion.”
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