Why boiler feed water needs to be treated?
The primary medium for producing steam is water. In addition to extending the life of the boiler, appropriate conditioning can boost the boiler's efficiency. Boiler water treatment also guarantees dependable and secure operation. The boiler itself could be ruined if not treated properly.
Impurities in raw water and how they affect a boiler
Total alkalinity in raw water mostly refers to bicarbonates. Raw water doesn't contain any hydrogen ions. Raw water's total alkalinity is significant since it could be a source of scale.
The bicarbonate ions in raw water are the main cause of alkalinity. Bicarbonate ions break down into carbonates and carbon dioxide when heated. Further heating will decompose the carbonate into caustic and carbon dioxide, if a soluble salt forms.
Depending on the operating pressure, caustic in the boiler water might or might not be preferred. Condensate line corrosion is mostly caused by carbon dioxide.
Calcium is the primary cause of hardness in the bulk of raw water. Scale is mostly caused by calcium salts in boiler and cooling water systems.
When it comes to chloride salts, scale is not an issue, but they are extremely corrosive in an oxidising atmosphere. In crevice corrosion and pitting, chlorides are prevalent. There should always be precautions made to avoid chloride concentrations, in designs or operations.
The most common type of iron is soluble ferrous. Iron changes to ferric form and produces insoluble hydroxides or oxides, when it comes into contact with air or oxidising substances. Iron should be lowered or regulated if it is greater than 0.3 ppm.
In boiler water, magnesium typically produces silicates or hydroxides, which are acceptable sludge types. Low boiler water alkalinity frequently results in the formation of unwanted magnesium phosphate, which is gummy and scale-forming. Magnesium only precipitates in cooling water systems when the pH is greater than 10.0.
The pH of the raw water will be between 5.5 and 8.0. Corrosion can be caused by a low pH, while scale formation can be caused by a high pH.
Silica content of 70–80 ppm is not rare, and it is typically present in ground water. In high concentrations, silica can lead to scale issues in boilers and cooling water systems.
Since, silica can evaporate and deposit in low-pressure sections of turbines and super-heaters, silica control is crucial, especially in high-pressure boilers.
Soluble ferrous iron is the most prevalent form of iron. When iron comes into touch with oxygen or other oxidising agents, it transforms into ferric form and generates insoluble hydroxides or oxides. If the iron level is more than 0.3 ppm, it needs to be reduced or controlled.
Magnesium commonly creates silicates or hydroxides in boiler water, which are acceptable sludge forms. Low boiler water alkalinity commonly causes the undesired, sticky, scale-forming magnesium phosphates to occur. In cooling water systems, magnesium only precipitates when the pH is higher than 10.0.
What are the Need of Boiler Feed water Treatment?
The two main types of boiler water issues are corrosion and deposit-related, while, treatment of boiler feedwater is necessary:
a) To avoid corrosion in the steam system and boiler
b) To stop deposits and scales from forming on the heating surface
Issues with boilers brought on by poor boiler water quality
a) Foaming: It causes the majority of carryover issues with boilers and is typically caused by, an excessive concentration of particles in the boiler water.
b) Corrosion: The most prevalent instance is when oxygen attacks steel. This happens in condensate return lines, boilers, pre-boiler systems, and water supply systems.High temperature and low pH both hasten oxygen attack
Fe3O4 + 4H2 = 4H2O + 3Fe.
c) Heat transfer: It is slowed down in a boiler due to scale build-up, which causes plates and tubes to overheat, swell, and rupture.
d) Presence of oxygen:The presence of oxygen in boiler water causes corrosion and pitting due to electrochemical action.
e) CO2 in boiler water: It creates ferrous carbonate, transforms it into ferric hydroxide, and then produces rust-coloured ferric oxide.
f) Hydrolysis:As a result of hydrolysis, mineral acids, unstable Ca and Mg salts, and overheated tubes are produced.
g) Untreated water: It causes tube walls or plates to pit and thin from the water side.
h) Oxygen that has been dissolved in water: It results in corrosion of surfaces due to an excess of hydrogen or hydroxyl ions, which affect pH either negatively or positively.
h) pH: Water has a very low corrosive activity because of it is distinctly alkaline.
Process for Treating Boiler Feed Water
There are two main categories of boiler feed water treatment: exterior treatment and internal treatment.
· External treatment
Prior to being put into the boiler, raw water is treated. This is referred to as external treatment. The intention is to raise the water's quality before it is used as boiler feedwater.
From a technical standpoint, treatment procedures attempt to lower alkalinity, hardness, silica, iron, manganese, turbidity, bacteria, organic matter, and others. One of the crucial parameters is hardness, which is a crucial scaling factor. Ion exchange or another external procedure removes hardness.
· Internal treatment
In addition to external treatment, a number of water treatment systems (internal treatment) have been created, to address the issues of scale accumulation and boiler corrosion. In the event of internal treatment, chemicals are added to the boiler water, and the salts that have precipitated are eliminated, during a blowdown.
There are many sites where Netsol Water provide facilities for water treatment, including the treatment of boiler feed water. High quality standards are associated with the quality attributes and as a result, we provide you with further engineering and consultancy, while personally adjusting your system to your workflow.
Why should you select Netsol Water as the manufacturer of your water treatment systems?
We are the leading producer and supplier of commercial RO Plants, industrial RO systems, water softeners, etc., in India. Our system is exceptionally reliable and cost-effective for use in an industrial environment. We work with each of our clients to give high-quality filtration systems at affordable pricing since, we are aware that you need the best systems available, at fair and competitive prices.