PRODUCTION • PROCESSING • HANDLING
Coolers and their problems M
Femke Schaefer discusses what can be done to tackle the issues of capacity, noise, energy consumption, plot space, pollution and cross-winds in coolers
any oil and gas applications rely on air-cooled coolers, particularly in areas where water-cooling is either not available or no longer allowed. In air-cooled coolers, the ambient air is
used to cool (part of) a process. Tat is why coolers are always positioned outside. However, this also makes them more sensitive to factors that affect their capacity, such as cross-winds, pollution by dust and pollen, and air pollution. Furthermore, because they are situated outside, the noise of the fans results in coolers often being one of the greatest causes of noise in a process. Besides that, they take up a lot of space and consume a lot of energy. However, there are a number of solutions to these three problems – and even for all three problems at the same time.
CAPACITY PROBLEMS DUE TO POLLUTION Pollution of the bundles of tubes is a well-known problem that occurs everywhere where bundles are located close to trees, roads, agricultural land and cities – in other words, practically everywhere on land. And what if your bundle looks like the one in the photo on the right? Well, you’ve probably long- since resigned yourself to the fact that your cooling capacity is limited or that it has become a bottleneck in your process, yet you need to find a solution fast because you have very little cooling capacity left! Tere are solutions, but they’re often temporary or they only clean the bundles on the outside (because deep cleaning is difficult), which means that your cooling capacity will still not be optimal and is likely to deteriorate again in the course of time anyway. But suppose there were some as yet unknown solutions that might yield unprecedented benefits? And suppose you could take them just that little bit further? So let’s say you are the proud owner of some polluted bundles, as shown in the photo. Tis bundle evidently needs cleaning, and the most obvious way to do that would be to use water. However, if you don’t choose the right method (high-pressure water or foam on the inside of the machine), there is a good chance that you’ll only manage to clean the first row and not the rows behind. Added to that, the fins often get sprayed flat, and this actually reduces heat transfer. Other
44
www.engineerlive.com
solutions are also possible, but many of them require the equipment to be switched off as it cannot be cleaned while the fans are still running. Tis could cost you a lot and is therefore an unappealing prospect for oil and gas projects, where downtimes can be considerably more costly than in other sectors.
ALTERNATIVE SOLUTION Te alternative here is dry cleaning, which is ideal for induced and forced-draft cooling bundles. A special (non-toxic, biologically degradable) powder is sprayed on the bundles using low air pressure (5-6 bar), and in effect this blows the dirt off the fins. With this method, you no longer need to walk over the bundles, the fins remain undamaged, all the rows of fins are actually cleaned, and, if you use induced draft, you don’t even have to switch off the fans. Bronswerk recently managed and supervised a project whereby bundles were cleaned using this method. Te result was a very satisfied and enthusiastic customer thanks to the efficient maintenance solution and the ultimate result, as shown in the second photo. Te lower costs and increased effectiveness of the process added up to efficiency in terms of minimal downtime, greater reliability and availability and maximum output of the asset.
ONE STEP FURTHER After dry cleaning, the cooling capacity returns to the desired level – that is, if you don’t take into account cross-winds or wind in general. Te maximum wind speed at which an A-frame cooler is tested and which it must withstand to officially
A prime example of heavily fouled tubes
The visible difference that efficient cleaning makes
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56