Cooling Towers, evaporative condensers and fluid coolers are a specialised heat exchanger during which air and water are brought into direct contact with one another in order to reduce the water’s temperature. The heat process water enters the cooling tower from the highest by way of spray nozzles, which is referred to as the distribution system. The water then enters the fill medium where air can be introduced by the cooling tower followers. The fill gives a better surface space for the flowing tower water. This permits for optimum contact between the air and the water, which allows for better evaporation rates. This evaporation removes heat from the remaining water, which is collected within the chilly water basin and returned to the system to absorb extra heat. It is thru this process that heat is faraway from the building through the evaporation of the water.
Water Issues with Cooling Towers?
Corrosionof cooling towers and condenser system parts resembling circulating pumps, condenser tubes and tube sheets can turn into very costly when it comes to service disruption, lack of production, elevated upkeep and capital gear alternative. The commonest types of corrosion present in cooling water equipment are;
General Corrosionoverall deterioration of the metallic surface, with an accumulation of rust and corrosion merchandise in the piping and sump. On copper condenser tubes it is noticed as a surface gouging or a uniform thinning. Typically this can be a uniform loss of metallic, not localized.
Oxygen Pittingthe second sort of corrosion most frequently encountered in heat switch equipment is pitting. Pitting is characterized by deep penetration of the metal at a small space on the floor with no obvious assault over your complete floor as in general corrosion. Oxygen pitting is caused by the presence of oxygen in the water. Corrosion takes place at a particular location on the metal floor, and corrosion products steadily accumulate over the pit, forming a blister or tubercule. Cooling towers are regularly made up with make-up water to compensate for the system water losses on account of evaporation. The make-up water is saturated with corrosive oxygen always throughout tower evaporation and therefore creates situations that are perfect for corrosion.
Galvanic Corrosionoccurs when totally different metals come in touch with each other in water. When this happens an electric present is generated similar to that of a storage battery. The more lively metal (ie. Iron) will are likely to dissolve in the water, thereby generating an electric current (an electron flow) from the less energetic metal (ie. Copper). This can be a standard prevalence in the tube sheet in cooling tower condensers as a result of copper condenser tubes involved with the ferrous iron finish plate.
Concentration Cell Corrosioncan be a form of pitting corrosion that is localized, but it’s often referred to as “under deposit corrosionor “crevice corrosionsince it happens under deposits or crevices of a steel joint. Deposits of international matter, dirt, organic matter, corrosion merchandise, scale or any substance on a metallic surface can initiate a corrosion response on account of variations within the environment over the metallic surface. Maintaining clean surfaces can best stop this type of corrosion so that the treatment inhibitors can present the required protection.
Microbiologically Influenced Corrosion (MIC)is a type of corrosion prompted or influenced by microbiological organisms or natural growths on metals. There are numerous kinds and mechanisms of MIC involving many types of microbiological organisms. The essential causes of MIC found in recirculating cooling water techniques are;
By way of the process of evaporation of the cooling water, minerals (ie. calcium, magnesium, iron, silica) in the make-up water are regularly cycled larger. When mineral concentration exceeds the solubility point, these minerals can precipitate out of resolution and promote scale deposits, reminiscent of calcium carbonate. The formation of scale deposits may end up in a lack of cooling transfer efficiency, translating in increased cooling costs. The heat power transferred from one floor to a different floor is termed as thermal conductivity. Heat transfer happens at a lower fee across supplies of low thermal conductivity than throughout materials of excessive thermal conductivity. As seen in the graph below, the thermal conductivity of calcium carbonate scale may be very low compared to the metallurgy in cooling tower systems. The energy required to transfer the same heat across any mineral scale formation such as calcium carbonate will tremendously enhance. The result is tremendously increased power costs as famous in the following desk. Scale in cooling water methods can embody international substances reminiscent of corrosion products, organic matter, and mud or dirt. Remedy packages are required to inhibit and management scale crystal formation. Cooling water systems additionally require sufficient dilution of the recirculating water (bleedoff) to prevent the focus of minerals from approaching the Saturation Level.
Cooling towers have optimum temperature and sunlight exposure to lure a wide range of life kinds and nutrient sources, causing a perfect breeding floor for biological fouling comparable to algae, fungi and bacteria. A few of these types circulate throughout the condenser system, whereas others attach themselves to handy surfaces. Corrosion is continuously found beneath these deposits. The organisms that develop in such programs consist primarily of algae, fungi and bacterial slimes.
Algaeare the most primitive type of plant life and together with fungus type the family of thallus plants. The form of algae present in open recirculating systems are the blue-green algae, inexperienced algae, and brown algae. Giant lots of algae can cause critical issues by blocking the air in cooling towers, plugging water distribution piping and screens, and accelerating corrosion by focus cell corrosion and pitting. Algae must be removed bodily earlier than a system may be cleaned for the reason that mass will present a steady supply of fabric for reproduction and biocides shall be consumed solely on the surface of the mass, leaving the interior alive for additional development.
Fungiare also a thallus plant just like the unicellular and multicellular algae. They require air, water and carbohydrates for development. Fungi and algae can grow together; the algae residing inside the fungus mass are furnished with a moist, protected atmosphere, while the fungus obtains carbohydrates from the algae.
Bacteriaare microscopic unicellular residing organisms that exhibit each plant and animal traits. They exist in rod-shaped, spiral and spherical kinds. There are lots of 1000’s of strains of micro organism, and all recirculating waters contain some bacteria. The troublesome ones, nonetheless, are bacterial slimes, iron micro organism, sulfate reducing micro organism, and pathogenic micro organism.
Cooling towers have been found to provide preferrred breeding situations for pathogenic micro organism resembling Legionella pneumophila. LegionnairesIllness is a potentially fatal form of pneumonia and is thought to be transmitted to humans by way of airborne water deposits.Tempo Chemicals Ltd.has launched a Legionella Consciousness and Threat Administration upkeep plan with ourPolicy Guideline LEG 2015-07. The purpose of this guideline is to offer info and steerage to our customers to minimize the potential for Legionella contamination of their recirculating cooling water techniques. Seek the advice of with yourPACErepresentative for ourPolicy Guideline LEG 2015-07and turn out to be familiar with this advisable cooling tower maintenance plan.
Bacterial Fouling Management
Biological fouling in cooling tower systems can be controlled by developing a water therapy program that includes the addition of Biocides. Biocides can include oxidizing and non-oxidizing type treatment products. To supply efficient control, regular assessments needs to be carried out to maintain the overall Aerobic Bacterial depend <10,000 CFU/ml with dipslide area tests. This may be monitored with a mix TTC/Malt Agar dipslide that exams for each aerobic bacteria and yeasts & mold.
Pace Chemicals Ltd.Remedy Packages for Cooling Towers
Pace Chemicals Ltd.has developed a comprehensive remedy program to inhibit:
Corrosion & Scale Inhibitors
Pace Chemicals Ltd.SCALE Professional cooling tower merchandise are advanced corrosion/scale inhibition formulations that provide;
Biological Fouling Inhibitors
Suggest dosing cooling towers with two biocides (oxidizing & non-oxidizing) with an automatic dosing system proportional to the system volume to inhibit biological fouling,
BromMax 7.1 is a stabilized oxidizing bromine biocide that provides:
MICROCIDE CA-39 or MICROCIDE WT-640biocides which will present;
Seek the advice of with yourPACE consultant for more information on new building or bettering your present water remedy. E-mail us at email@example.com if you need a survey of your cooling water system.