Here in the Phoenix metropolitan area, opposed water situations require clever water therapy strategies to adequately maintain water cooled equipment. Proper management of the characteristics of the cooling tower sump water together with maintaining good tower hygiene in general accomplishes no less than 4 optimistic things.
- 1) It avoids losing excess water.
- 2) It inhibits scale formation.
- Three) It controls biological development.
- 4) It reduces the corrosion fee of metallic components within the tower.
Let’s focus on how a cooling tower operates to grasp why correct water therapy is necessary.
Most residents within the valley are conversant in an evaporative cooler. Water from the evaporative cooler sump is circulated by a pump over pads in the evaporative cooler and outside air is drawn by means of the pads. As the air is drawn by means of the wet pads among the water evaporates and cools the air. The cooler air is then circulated into the space the place cooling is desired. Within the strategy of cooling the air, the water being recirculated across the pads is also cooled.
That is exactly the identical precept being employed in the cooling tower, but on a a lot grander scale. Rejecting giant portions of heat from a building’s mechanical system requires a lot of water to be evaporated. For example, a one hundred ton water cooled chiller working at full capability for 24 hours would require the evaporation of more than 4 thousand gallons of water. That brings us to the subject of the characteristics of the make up water. Make up water is the water supply that replaces the water being evaporated in the cooling tower.
Right here within the metro area, water conditions vary extensively because our water comes from a number of different wells in addition to floor sources. The water quality could change rapidly over a brief period of time because different sources are utilized for the water provide. Every well has different water traits and they often vary broadly from one side of town to the opposite. Water that comes from surface sources, just like the Central Arizona Project will normally have considerably completely different characteristics than effectively water. Floor water quality may also be influenced by weather situations corresponding to drought or elevated runoff.
As water evaporates in the cooling tower all the non-unstable parts keep behind in the sump of the cooling tower. There is definitely much more in water than what we’d name hardness (carbonates). There are also chlorides, suspended mud particles and biological microorganisms. As increasingly more water is added to replenish the water that’s being evaporated, these dissolved and suspended components within the sump water proceed to accumulate. If no measures are taken to control the focus of these components within the water, the answer finally will increase in focus to a point where “stuff” begins coming out of answer. This “stuff” finally ends up getting deposited on the surfaces that the water comes involved with.
Have you ever ever seen an evaporative cooler where the pads have not been modified for a protracted whereas? I’ve seen them so encrusted with mineral deposits that the blower may not pull air via them. I’ve also seen them produce a bounty of biological development within the sump water. That is exactly what’s going to happen in a cooling tower with out adequate attention to hygiene and an applicable water treatment strategy.
When solids which are dissolved in water come out of solution they’re deposited first on heat alternate surfaces and surfaces where the water is being evaporated. Heat exchangers, water cooled condensers, drift eliminators, the tube bundle in closed circuit cooling towers and the fill in open cooling towers are a couple of examples of surfaces the place this occurs.
Deposition of mineral scale, dirt and biological fouling on any heat trade surfaces may end up in diminished heat switch, decreased tower efficiency and elevated vitality prices. While reducing deposition of those is necessary with regard to the cooling tower, it is completely critical to avoid scaling or fouling in the water cooled condenser. Scaling and fouling in the condenser significantly reduces heat transfer capability and can critically affect power prices, performance and reliability.
A two half technique is usually employed to handle the mineral content material of the sump water. Half one is to maintain the sump water pH inside allowable limits and to feed the right type and amount of chemicals to assist the water keep extra of the dissolved solids in resolution. Half two is intentionally sending a few of the sump water down the drain (blow down). Blow down reduces the extremely concentrated mineral content of the sump water by diluting it with the recent make up water being added to replace the deliberately wasted water.
Biological progress can also change into a major well being danger depending on the actual organism involved. Permitting mud and biological development to accumulate within the sump of a cooling tower can speed up corrosion of the sump and shorten the life cycle of the cooling tower. It may also present a haven for microbes to flee the effects of a biocide.
Proper water treatment technique and good cooling tower hygiene will not be a one dimension matches all resolution. The quality of the make up water will require an adjustment of the type of the chemicals and biocide utilized. It might also require changing feed and blow down rates for correct control. As well as, these requirements may be altered by the characteristics of each particular person cooling tower installation.
In keeping with Alan Bateman of DB Water Technologies, there are several things a good cooling tower water treatment program should address with a purpose to be effective. They’re complete dissolved solids (TDS), hardness, pH, chlorides, suspended solids, an appropriate technique for biological control and a proper blow down strategy. Each cooling tower manufacturer publishes suggestions for maintaining correct water situations of the sump water. The advice of a professional water treatment skilled is advised to ensure that every item above is included in your general technique for cooling tower water treatment.