Feed Water Tanks — Maximising Boiler Efficiency
Posted on: 13 April 2020
Feed water tanks are used to remove gasses that cause corrosion mainly in boiler tanks. Oxygen and carbon dioxide are the main gasses in water that cause corrosion.
There are several types of feed water tanks:
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Feed water tank with a head- These are large vessels fitted with a headpiece usually made out of stainless steel. Although these are typically more expensive, the cost is justified by the longevity of the feedwater tank. Inner parts of the tank are also made out of acid-proof stainless steel that prevents degradation of these parts.
- Stork system feed water tank- These consist of a special nozzle and an internal chamber system to remove gases that cause corrosion from water. These gases are removed from the water flowing through the boiler and generator. One of the major advantages of this type of feed water tank is that it has a smaller height. This smaller height means that the tank is cheaper to manufacture and more cost-effective to run. This also makes the tank easier to install at heights.
Boiler Water Treatment and Issues in Feed Water Design
The way in which a feed water tank is set up and operated greatly influences the efficiency of the boiler. The feed water pump location, for instance, is critical in regulating the temperature of the water inside the boiler.
The water inside the boiler must be treated appropriately to ensure that the boiler operates efficiently. Treatment includes injecting chemicals into the water to protect the tank from molecules that cause degradation. One common mistake is injecting the chemicals into the wrong area of the tank; this can actually have a negative impact on water quality. The most appropriate point of chemical injection is underneath the waterline.
Another common issue in feed water tank design is incorrect heating of water. The water entering the tank must be heated, failure to do so can result in thermal shock. This is why it is important to look for features that ensure that water temperature is heated appropriately. Selecting a water tank fitted with a device called a steam sparger ensures that water is appropriately heated. This also helps to reduce the oxygen content of the water and hence reduces any damage to the tank from scavengers i.e. molecules that cause corrosion.
As can be seen, the feed water tank must be carefully designed and operated. When selecting a feed water tank, all of the possible issues must be taken into consideration to maximise boiler efficiency.
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