Heat exchanger tube cleaning and general maintenance is a necessary part of keeping a system in good working order. Heat exchangers are to be found in a number of industries, notably in oil refineries and the chemical industry. Their function is to transfer heat from one source to another; usually from one liquid to another liquid. Water jetting is the most common method used for heat exchanger tube cleaning. This entails ultra high pressure water jets being directed on to the scale in order to remove it. Automated system can perform water jetting remotely, thereby ensuring the maximum safety for operators.
The two liquids are not usually in contact with each other, but have a wall of high thermal conductivity between them. In the oil industry the most common type of heat exchanger is the shell and tube design. This design entails a large circular metal pipe construction, the shell that has a bundle of tubes contained inside.
The heat exchange takes place when one liquid is introduced into the shell and another is introduced into the tubes. The two liquids are at different temperatures and heat is exchanged between them, usually for the purpose of cooling one of the liquids down.
The shell and tube design of heat exchanger is a complex one. Cleaning it may seem a daunting task, but it is actually achieved more easily than might be imagined. Heat exchanger tube cleaning is necessary for several reasons. It is required, for example, prior to an inspection of a heat exchanger tube bundle, especially if the tube bundle is made of metal.
An inspection of a tube bundle is carried out by use of an Internal Rotary Inspection System. This involves introducing a probe that has a rotating mirror that can direct an ultrasonic beam onto the wall of the tubes to measure any pitting or corrosion. The mirror is rotated by a small turbine that is driven by the pressure of water that is introduced into the tubes. The probe is drawn along the tube slowly to provide a continuous chart record of the tube’s internal condition.
During normal operation the inside of the tube bundle can become badly scaled. This has a dramatic effect on the efficiency of the unit, greatly reducing its ability to function at maximum capacity. For this reason it then becomes necessary for tube cleaning to take place in order to bring the unit back up to standard.
Water jetting is the most common method used for heat exchanger tube cleaning. This entails ultra high pressure water jets being directed on to the scale in order to remove it. Automated system can perform water jetting remotely, thereby ensuring the maximum safety for operators.
De-scaling cleaning operations are usually performed on site, which means that the heat exchanger and its tube bundles do not have to be removed. This helps to ensure a minimum of time is spent when the heat exchanger can not be in use.
C. J. Rose writes on the subject of heat exchanger and tube bundle cleaning for Sureclean, global waste management services. Topics include HP & UHP water jetting, tank/vessel cleaning, vacuum transfer/pumping, industrial painting, asbestos management/removal, HVAC/duct management, NORM management. For videos see http://www.sureclean.com/video/
