Question

Foaming is a phenomenon that occurs in the boiler feed water due to ________
1. manganese
2. sodium chloride
3. oil
4. nitrogen peroxide

Answer 1

Correct Answer - Option 3 : oil

Explanation:

Foaming:

Definition

• ​Boiler water carry-over is the contamination of the steam with boiler-water solids. Bubbles or froth actually build up on the surface of the boiler water and pass out with the steam. This is called foaming and it is caused by a high concentration of any solids in the boiler water.

Causes

• Alkalis, oils, fats, greases, certain types of organic matter and suspended solids are particularly conducive to foaming.

Process

• Suspended solids collect in the surface film surrounding a steam bubble and make it tougher. The steam bubble, therefore, resists breaking and builds up foam. It is believed that the finer the suspended particles the greater their collection in the bubble.

Measures

• Maintain the concentration of solids in the boiler water at reasonably low levels.
• Avoiding high water levels, excessive boiler loads, and sudden load changes
• Very often contaminated condensate returned to the boiler system causes carry-over problems. In these cases, the condensate should be temporarily wasted until the source of contamination is found and eliminated.
• The use of chemical anti-foaming and anti-priming agents, mixtures of surface-active agents that modify the surface tension of a liquid.
• Remove foam and prevent the carry-over of fine water particles in the stream, can be very effective in preventing carry-over due to high concentrations of impurities in the boiler water.