Cleaning Heat Exchangers with High- and Ultra-high-pressure Water
a report by Wout Bol1
and Joost Ballieux2 1. International Sales Manager; 2. Director, Peinemann Equipment
High-pressure water has been used in the chemical and petrochemical industries as a cleaning agent for many years. One of the most important applications is the cleaning of heat exchangers and Peinemann have been at the forefront, forcing through the change to automatic operation. Nowadays, there are a wide range of high-pressure accessories available that can carry out heat exchanger cleaning. In most cases, heat exchangers are removed for maintenance and transported to a dedicated cleaning bay where they are cleaned both internally and externally by semi-automatic equipment. Most of the work involves cleaning heat exchanger bundles such as condensers, cooling tower bundles, evaporators and heat exchanger shells. For every cleaning job there are different types of machines. But, as with many things, you have to plan and determine your best and most suitable option before starting any heat exchanger cleaning job. For example, when a small cleaning job is required, the smaller single lance (LTC) machine could suffice, whereas with large jobs, multiple lance machines (IBC-5) would be more suitable (see Figure 1).
Unfortunately, it is not always that easy and other factors such as available space, time constraints, type of contamination deposits and budget will have to be taken into account. The various types of machines available for cleaning heat exchangers will follow later in the article.
The energy required to carry out the cleaning process is largely dictated by the contamination (deposits) to be removed. Table 1 indicates various pressure and flow rate requirements:
Technical Data for Heat Exchangers
Shell and tube exchangers are generally a bundle of tubes 1–12m (3–40ft) long, with tubes being 12.5–50mm (0.5–2 inches) in inner diameter. There can be from one hundred to several thousand tubes in a bundle, which is usually circular in shape. The diameter is usually 0.3–3.5m (1–12ft). Shell and tube bundle sizes are designated in Table 2.
How to Extract and Refit Heat Exchangers Since the development of the first so-called ‘bundle pullers’ in the late 1960s, this successful product has gone through some major changes. Whereas the first bundle pullers were huge, air-driven and slow machines, the new design is all self-contained, easy to operate and slim, making it possible to pull nearly any bundle with minimal effort. As the world changes around us, so does the size and weight of the bundles. New plants often have larger and heavier bundles than ever expected.
The aerial bundle extractor (see Figure 2 and Figure 3) is a self-contained unit, which is easily lifted in position by crane. It is equipped with an air-cooled diesel engine, which drives the hydraulic system and is operated via (wireless) remote control. Aerial bundle extractors can lift heat exchangers between one and 100 tonnes capacity, until asked
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for bigger. The bundle extractor is clamped to the exchanger by means of two hydraulic clamps at the front of the machine. With a powerful hydraulic winch, ranging from 25 to 100 tonnes pulling force, it becomes easy to pull the exchanger out of the shell without putting any stress on the foundation. The pulling winch is equipped with a vertical lifting pull hook system which can hydraulically raise and lower to make sure the bundle is always in line with the shell while pulling. Once the exchanger is pulled out, the operator balances the extractor by moving the lifting frame forwards or backwards with his remote control. The same principle applies to the self-propelled and truck-mounted extractors suitable for lower-placed heat exchanger bundles.
How to Handle Heat Exchanger Bundles
An important link in the cleaning process is the handling of the heat exchanger bundles and transport to the designated cleaning areas. For improved flexibility there are new bundle lifters (see Figure 4) available that can help with lifting heat exchanger bundles onto trailers and handle bundles in the cleaning areas in a quick and safe manner. Thanks to the large pick-up surface area and by spreading the force on the bundle, no damage is done to either the tubes or baffles. These ‘new’ systems are both safe (no more slings) and efficient. During turnarounds
An important link in the cleaning process is the handling of the heat exchanger bundles and transport to the designated cleaning areas.
it can take a long time before bundles are changed from the rollers. The latest development for lifting bundles is the Peinemann Combi Lifter (see Figure 5a and Figure 5b). This lifter can be used as an integral part of the aerial bundle extractor (main lifting frame) and also as a separate bundle lifter when disconnected from the aerial bundle extractor. After pulling out a heat exchanger, the Combi Lifter can be put on the ground and the lifter can easily remove the heat exchanger without disconnecting the crane. The bundle can be easily lowered onto a trailer for transport to the cleaning area.
Cleaning of Heat Exchangers What
Both the inside and outside of heat exchangers are prone to contamination/fouling. These are common problems for heat exchangers, especially when dealing with hard-to-clean products.
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Heat Exchangers
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