Boiler water treatment is a type of industrial water treatment focused on the removal or chemical modification of substances potentially damaging to the boiler. Varying types of treatment are used at different locations to avoid scale, corrosion, or foaming. Steam is required by many industrial and municipal operations used to drive turbines or engines, supply heat and process certain materials. A boiler is a closed vessel with an arrangement of drum vessels and tubes with a furnace or other heat source to generate the steam.
External treatment of raw water supplies intended as boiler feed water focuses on removal of impurities before they reach the boiler.
Internal treatment within the boiler is focused on limiting the tendency of water to dissolve the boiler, and maintaining impurities in forms least likely to cause trouble before they can be removed from the boiler in boiler blowdown.
A typical boiler has a lower drum/vessel known as the mud drum and an upper drum/vessel called the steam drum. These two drums are connected by a series of tubes where water is circulated. The tubes closest to the heat source are called raisers, and they circulate water from the bottom mud drum to the top steam drum where steam is generated. The tubes away from the heat source are called downcomers, and they circulate the water back down to the mud drum. As steam is removed from the boiler, an equal amount of fresh pretreated water replaces the water removed as steam.
Although we can remove most of the scale-causing contaminates through pretreatment, some contaminates still find their way into a boiler. Within the boiler is a a continuous blowdown located just below the interface of steam and water separation. This continuous blowdown controls the water chemistry within the boiler and prevents scale contaminates from becoming saturated. In addition, there's also a blowdown valve on the bottom of the mud drum, which is periodically opened to remove any larger particles that may settle out in the boiler.
Once steam is generated, it completes its function and condenses: this condensed steam is known as condensate. Condensate is of very high quality water and often returns to the boiler since ver little pretreatment is needed for condensate. Although condensate is very high quality water, it is also extremely corrosive.
Power industry boilers generate steam under very high pressure. This steam is heated to produce superheated steam which in turn spins a turbine to produce electricity. Power generation requires extremely high quality water and steam, which is needed to ensure an energy efficient operation.
Deposits in a high pressure boiler can be catastrophic causing incorrect heating (hot spots) which can cause metal failure: deposits on turbine blades can cause loss of balance disrupting electricity generation.
Preheats feed water. Using exhaust heat from combustion
a. Steam drum releases steam
b. Feedwater line brings feedwater into boiler
c. Continuous blowdown continuously removes contaminants
d. Riser brings hot water to steam drum, boiler tubes closest to heat source
e. Downcomers bring less hot water to mud drum, boiler tubes furthest from the heat source
f. Mud drum is the bottom drum, heavier solids area
g. Manual bottom blowdown manually removes heavier contaminants
Brenntag offers many products to properly treat boiler water issues such as scaling or corrosion including: