Timely Cleaning Of Heat Exchanger For Better Performance

Although cleaning heat exchanger could be a tedious, time-consuming, and costly procedure, but it is imperative that the equipment is in excellent working condition. It is already known that high temperatures can affect machinery and equipment badly, especially when there is a rise and fluctuation of temperatures constantly, which could harm the equipment if they are not kept cleaned. Heat exchangers are often taken for granted, as they keep on providing their duty till their efficiency drops gradually, and it becomes a problem. The situation arises due to it not getting cleaned properly and keeping it online. And when it comes to cleaning, few know the performance level of the exchanger, which usually results from either loss of the drawings, or there are no records of what improvements have been done after its initial cleaning. And as the exchanger is opened to find out the level of fouling, it is seen to be so severe that the time to clean is stretched than previously planned. And all these result in a loss of production. And when cleaning is done, it is mostly without any knowledge of the extent of cleaning required and what will be the effects and what extent the results will last. A widely used heat exchanger configurations seen in most of the industries is the hairpin shell-and-tube exchanger. With the presence of thousands of small-bore tubes, scaling could require major work to bring back the exchanger to its original performance. If there is even scaling in the outside of the bundle, there is a greater need of cleaning. However, working closely with people involved in designing heat exchangers will bring in a considerable improvement in heat exchanger accessibility and proper cleaning. Better design will result in an improvement in cleaning and lead to a faster, safer and cleaner working of the exchanger with better waste containment. The exchanger will get cleaned, back to its bare metal and will operate faster. It is the throughput on which plants are usually specified, and not on the ease-of-cleaning and accessibility. This leads to designing heat exchangers in an improved capacity of 30 to 40 percentages so that they can keep working, even when the level of fouling is quite heavy. Nowadays, heat exchangers are made that could clean in one of the three processes like chemical, mechanical or pressure approach. Like other industries, maintenance of refineries is usually done similarly, and this includes shutting down for a 21 day period. This is the method of cleaning adopted using high-pressure water to clean. Usually, many companies consider their heat exchangers as a separate unit and work in extending their run-time, instead of designing or re-designing them that could help in better and faster cleaning. On the optimization of a plant for cleaning, it is possible to maintain full production all through the process of cleaning. Doing minor mechanical changes could mean the exchanger or exchangers could be removed and made to undergo cleaning process, as others keep working. Redesigning of the exchanger would mean that it is possible to remove the header and cleaned using a different process, which would complete the job within few hours in place of several days. It is also possible to reduce the frequency of build-up of future fouling by having improved cleaning cycles and which would lead to a reduction of the chances of tubes corrosion due to the exchanger remaining open for cleaning for a long time and the chances of corrosion from ambient atmosphere increasing. Hence, with a smoother surface of the heat exchanger, there will be a better transfer of heat as well. If there is fouling up of the exchanger later on, it becomes easier next time to clean it using any of the systems that is adopted. This would lead to a change in cleaning heat exchanger procedure to what it has been since the 1980s. Nowadays, the usual service intervals are extended to 3 to 4 years; however, the evident operational savings are a false economy. While the shareholders are laughing their way to the bank due to longer run times, the rival refineries only have the option to go ahead with the same process or else, find themselves losing millions during occasional closures. Four years hence, there will be major cleaning and maintenance of the plant and there will be much higher capital replacement cost than what it had been.

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