Cooling water
Cooling towers are used in most industries. Calcium deposits or corrosion are ubiquitous in these systems, leading to energy losses and high costs due to reduced conductivity. In the worst case scenario this can result in complete failure of cooling equipment, and potential disruptions in production. In order to improve performance and safety and guarantee a longer system life, the composition of the make-up water and the water in the system should be strictly controlled. Optimal water quality is crucial for reliable operation of cooling systems. The right choice of filtration equipment and chemicals, such as biocides and corrosion inhibitors maximizes the service life of systems and minimizes maintenance costs.
Operating problems in refrigeration systems
Circulating water quality problem
Poor water quality in cooling systems causes many major problems. Untreated water is the cause of scale deposits on heat transfer surfaces, formation of corrosion, as well as the development of microbial life and sediment clogging of systems. Deposits accumulated on the pipe surface cause additional thermal resistance, which reduces the heat transfer coefficient. A layer of just a few millimetres can reduce heat transfer by 20%. The use of chemical agents for water treatment and conditioning in refrigeration systems can minimize the occurrence of corrosion, reduce pollution, reduce limescale and microbial deposits, and ensure maximum safety and operational efficiency of equipment. By selecting the appropriate chemical preparations you can obtain desired water parameters without causing pollution or environmental contamination.
Refrigeration system limescale
The main factors responsible for scale formation in refrigeration systems are the quality of make-up water and how the system is run. In a system that is constantly monitored and blown down on a regular basis out and where appropriate chemicals are added, scale build-up is prevented. Naturally, the best method to control scale is to prevent it from forming by using water with the right parameters. However, if a system has already been contaminated with scale, chemicals must be used to remove it. This is where corrosion inhibitors are used, which produce a special protective film on the metal parts of the system, and biocides, i.e. preparations that inhibit the growth of bacteria, algae and fungi accumulating on the walls of the system. Water treatment and conditioning are thus essential for the operation of refrigeration systems.
Corrosion in refrigeration systems
The most important chemical factors affecting the formation of corrosion in refrigeration systems are: pH reaction and pH value, the amount of oxygen and other gases dissolved in water, salt content and the presence of microorganisms. Physical factors such as location, temperature, water flow rate in the system, heat transfer and raw material composition of the system are also important. Copper pipes will be more resistant to corrosion than systems made of steel, including galvanized steel. An effective method of controlling corrosion of refrigeration systems is the use of chemical protective measures, such as corrosion inhibitors, which form a protective film on system walls, correcting water parameters, thus eliminating the causes of corrosion.
Incorrect blowdown of systems
Cooling processes using water as a refrigerant release water vapour into the atmosphere. Since part of water thus escapes from the system, it is necessary to continuously supply make-up water, which contains salts. Even if this water is pre-treated using filtering equipment, when only pure H2O water is continuously evaporated, the salt concentration in the refrigeration system keeps increasing. Excess salt causes scale to accumulate on system walls. In order to reduce this phenomenon, system blowdown should be carried out on a regular basis. This process consists in discharging an appropriate amount of water from the system, so that after adding make-up water, circulating water with appropriate salinity is obtained.
System passivation
When commissioning new refrigeration systems, special measures must be taken to ensure that galvanized steel surfaces are properly passivated and provide full protection against corrosion. Passivation is the formation of a protective, passive oxygen layer on galvanized steel surfaces. In order to ensure the passivation of galvanized steel surfaces, the required quality parameters of circulating water must be ensured for a period of four to eight weeks from the first start-up. Incorrect passivation can be the beginning of operational problems in the system.