Cleaning of water-cooled chillers
Water-cooled chillers play a central role in commercial (HVAC) and industrial cooling systems. In fact, these heat exchangers often have the highest energy consumption in a building. Just a small amount of deposits such as scaling can have a detrimental effect on the heat transfer. It is therefore extremely important to keep these systems in good condition.
A fouled water-cooled chiller will be less efficient and still consume the same level (or even more) energy. In addition, the lifespan of the installation and components can be shortened by keeping it in a fouled condition. The chiller is connected to several other systems throughout the building and/or cooling process, such as a cooling tower, plate heat exchanger, fan coil units and more. This means that a less efficient chiller will also impact the efficiency of all the connected systems.
When the condenser tubes have hard mineral desposits, such as scaling (calcium carbonate) a high-speed rotating brush might not be the best option anymore. Scaling is a type of fouling caused by inorganic salts in the water circuit of the heat exchanger. It increases the pressure drop and insulates the heat transfer surface, thus preventing efficient heat transfer. Only a small layer of scale, less than 1 millimeter can lead to a decrease in heat transfer between 20 to 40%.
In cases like these, it would be much easier and more effective to apply the CIP (cleaning-in-place) procedure. In this technique, a flushing pump is used to circulate a chemical cleaning agent through the condenser tubes of the water-cooled chiller. A preventive maintenance strategy based on the CIP procedure offers various advantages. It increases equipment efficiency, prevents malfunctions and saves on energy costs. On this page you can find more detailed information about how a CIP works.
Application and deposits
Cleaning and maintenance of the water-cooled chiller is mostly focussed around the condenser tube bundle. These tubes (inner side) are exposed to cooling water which can contain various types of deposits, especially when directly connected to a cooling tower. It is still important to periodically clean the evaporator tubes as well. The proper way to clean the tubes depends on the deposits inside of them. Water-cooled chiller condenser tubes usually contain deposits, such as:
- Scale and other mineral deposits
When cleaning soft to medium biological deposits, such as algae and slime, a rotary tube cleaner can be very easy-to-use and offer excellent cleaning results. With this method, a tube cleaning machine is connected to a shaft and brush. The brush rotates at high speed in the tube, removing deposits almost instantly. A low pressure water flush ensures that all the loosened deposits are flushed out. You can learn more about this cleaning technology here.
Advantages of CIP
Cleaning-in-place offers various advantages for the customer and equipment. Some of them have been listed below.
- A good combination of chemical cleaner and flushing pump will offer reliable cleaning results. Even hard deposits, such as scaling can be removed easily and effectively.
- A chemical cleaning-in-place (CIP) requires little labor. When all the hoses are connected and the chemical cleaner is flowing through the tubes, the operators just need to keep an eye out on the process. Almost no manual labor is required, other than periodically checking pH- and pressure levels and reversing the flow direction.
- Cost savings. When the system is cleaned periodically, the amount of deposits will not exceed the threshold where the equipment starts to malfunction or greatly decrease in efficiency.
- A preventive CIP program keeps the water-cooled chiller condenser/evaporator tubes in optimum condition. Due to the high cleanliness of the system, it is possible to ensure a stable, high efficiency close to the original values. High cleanliness also contributes to a longer lifetime of the system and the internal components.
A good combination of the cleaning agent, the mix ratio and the type of flushing pump will ultimately determine the cleaning result of the CIP. That is why you should always consult an expert before carrying out a cleaning-in-place.
Scalebreak-MP cleaning agent
Scalebreak-MP (multi-purpose) is the most widely used chemical cleaning product of Goodway Benelux. This is because it is hazardous-free, biodegradable and can be used on almost any tube material. Some types of materials which are unharmed by Scalebreak-MP are:
- (Stainless) steel