Published by James McDonald, PE, CWT, Technology and Marketing Manager at Chem-Aqua, Inc. in Academic
Category: Academic
I agree with most of the comments made prior to this one as to definitions.
Carry over is specifically any solid dissolved or suspended in boiler brine that becomes entrained in steam output as particles of solid material, micro-droplet mist, or generally wet steam. Physical causes include poor level control in boiler drums, poor upstream treatment of boiler make-up water, especially where high silt/clay surface waters are the source, and failure/misapplication of boiler internals (mist eliminators). Failure to use the correctly pure water for steam attemperation can also result in "carry-over" although this is actually resulting from direct contamination of the steam. Anything related to carry-over must be strictly prevented in Universal Pressure Boiler, or once-through boiler as all the water entering is converted to steam.
The impact depends upon the application, thusly for heat exchange carry-over may result in impingement attack of surfaces, leading to failure, deposit accumulation also will result in loss of heat transfer efficiency. For rotating equipment (bladed Rankine cycle turbines), deposits on blades will eventually spall off unevenly, and this gives rise to excessive vibration, or even sudden catastrophic failure of blade rows due to sudden release, gross rotor imbalance, if the problem is that severe.
Published by James Stewart
Carry over is a process to carry the Impurities and water treatment chemicals from boiler water into steam through mechanical and vaporous carryover. I.e salts of oxides, hydroxides, and silica. It can deposit in area of process for production.
Mechanical Carry-over reasons are following,
Vaporous Carry-Over (Volatility) - A distribution ratio concentration of a specific molecular compound in the steam to its concentration in the liquid water.
I have cover practical problem of boiler water treatment in my book Fundamental Boiler Chemistry & Preventive
Published by brajendra Singh, Regional Head at Ion Exchange India Limited
When it foams in Boiler upper drum the boiler water carries over along with steam. The loss in feed makeup and quality of steam matters. The steam remains wet as superheater also affected.
Published by MUHAMMAD ILYAS KHAN, DGM, Manager (Purification), Director New Ventures at (BST). at SSGC, PPL & BST
As a generalized category of carryover, I have always related it to be caused by the following but no exclusively to:
The impact, to name a few, will cause:
Published by Patrick Hall
High TDS (exceeding the recommended cycles of concentration)
surges in stream demand
poor design
contamination from condensate or improper chemical treatment
Published by Thomas Sclafani, Consulting Business Development and Strategic Sourcing