Saturday, January 8 2022

Condensate Corrosion and Protection

Condensate recovery is amongst the areas of energy source conservation hence widely employed in companies today. Condensate still is made up of about 20% of fats steam, in fact it is distilled normal water, almost free from dissolved solids. Therefore , their recovery provides advantages to boilers that include reducing energy costs, lowering chemical treatment, conserving water, and increasing boiler efficiency. Non-contaminated condensate, which can be the product in noncontact steam application, comes back to steam boiler's system as foodstuff water. There is two types in condensate obtaining system during boilers - the pressurized condensate program and the gravity-vented condensate system. The show steam right from high pressure condensate is restored by going back this condensate to the deaerator while the gravity-vented condensate dividends to the boiler feed reservoir.

Oxygen Harm

Often people says due to its pureness in characteristics; steam condensate requires no chemical treatment, but is that so? Condensate is rust and can be polluted by rusts, something that few people are knowledgeable. Sometimes, condensate can be slightly acidic. This is exactly why condensate piping deteriorates faster than water vapor piping. Air corrosion develops in condensate piping since pitting, which is the most dangerous form of corrosion.

condensation reaction of oxygen harm is:

4Fe + 6H2O + 3O2 → 4Fe(OH)3
Carbonic stomach acid thins condensate pipes to result in grooving at the bottom section of the pipes. The end result is, each time a condensate tube has mostly pitting, the condensate is rich in oxygen, however if the pipe outlet is thinning, the condensate pipe suffers from carbonic acid solution attack. Nonetheless where perform oxygen and carbon dioxide during condensate dispatch originate from? Are generally not all contained oxygen and carbon dioxide through boiler mineral water arrested by artificial means by the deaerator and chemically by sodium sulphite or DEHA from the boiler? Truly, there are two main reasons with this phenomenon. First, when vapor condenses, the flow quantity shrinks thus allowing much needed oxygen to integrate and melt. Secondly, air can also be driven into condensate system because of condensate pushes, leaking high temperature exchangers, and vents from condensate acquiring tanks.

Acid solution Corrosion

Carbon can mess up in the same way because oxygen, having said that, the main method of obtaining carbon dioxide through steam is the breakdown of bicarbonate and carbonate alkalinity in central heating boiler water to make carbon dioxide.

Listed below are the tendencies that transpire:

Carbonate kind of reaction: CO3 plus H2O → CO2 + 2OH
Bicarbonate reaction: 2HCO3 + heat → AS WELL AS + 2H2O
Carbon dioxide integrates with vapor, condenses through condensate to make weak carbonic acid, and lowers the pH. Condensate is so genuine that possibly small amount of poor carbonic acid can drop the ph level to four. 5.

The reaction is:

In Malaysia, there was a case in a petrochemical industry where less than 20% of the condensate was go back into the central heating boiler because of carbonic acid infiltration. In boiler, acidic condensate lowers pH, erodes metal, increases reduce iron, and increases the total dissolved solid waste (TDS) as iron bicarbonate. Iron bicarbonate mixes with boiler standard water to form iron bars oxide and carbon dioxide, and consequently the carbon mixes with steam once again. That is why a number of people cannot preserve a high pH in their central heating boiler despite duplicity the dosage of caustic soda. This problem in condensate recovery is normally disadvantageous to steam boilers and have to be prevented.


Protection in after-boiler condensate lines is required. Corrosion through condensate range can be decreased by volatile amines seeing that corrosion inhibitors. Volatile amines commonly used designed for condensate range protection today are normalizing amines and filming amines. Neutralizing amines react with carbonic acid and carbon to increase condensate pH to 9. Among the commonly used normalizing amines is definitely cyclohexylamine. Recording amines, however, form protecting films at metal surfaces and safeguard from much needed oxygen attack, the same way magnetite film does. One of filming amines is octyldecylamine. Having oil-like property, recording amines jacket the metallic surface with one-molecule wide. Filming amines have no impact on condensate ph level. Carbon dioxide and oxygen are definitely more corrosive in combination. Accordingly, each time a system encounters both fresh air and acid solution attacks, different both amines is always advised.

Besides chemical type treatment, condensate quality monitoring should be included on the daily or regular basis. Create a test of condensate to monitor iron bars content, solidity, and TDS. Check for coloring and order. Any modification indicates the wrong type of treatment or perhaps contamination. Condensate is not cured to remove damage, therefore , to stop iron hydroxide infiltration; permanent magnet filter might be applied to eliminate it from condensate. Total golf club in furnace feed drinking water for choice pressure central heating boiler should be minimal than 0. 05 ppm, and virtually any increase could mean straightener hydroxide infiltration from the condensate line. Meant for boiler functioning below zwanzig bars, a recommended alkalinity standing is one hundred and forty to seven-hundred ppm. In case the alkalinity level exceeds 700 ppm, bicarbonate and carbonate will breakdown producing carbon and drive in steam, as stated just before. However , the most effective method is to eliminate the alkaline firmness (carbonate and bicarbonate) convincinglydecisively, definitively, determinately, once and for all, once for all by using the reverse-osmosis system or perhaps demineralization.


Finally, condensate is corrosive and harmful to condensate piping. The danger happens when a large number of steam designers, based on fantastic boiler normal water field-test results, feel comfortable with the boiler mineral water treatments. A handful of engineers do not seriously consider or simply realize the potential damage that may happen to the condensate lines. This is a heavy negligence. In the event that leaks after leaks will be detected, it can be too late and costly repairs would be inescapable. It is the take care of condensate profit that makes it unneeded to replace condensate piping for quite some time.