Why is boiler feed water treatment important?
The most appropriate boiler feed water treatment system will help the facility avoid costly plant downtime , expensive maintenance fees, and boiler failure as a result of scaling, corrosion, and fouling of the boiler and downstream equipment . But what is a boiler feed water treatment system and how does it work?
What is dealkalization in boiler water?
Dealkalization. After the softening process, some boiler feed water treatment systems will utilize dealkalization to reduce alkalinity/pH, an impurity in boiler feed water that can cause foaming, corrosion, and embrittlement. Sodium chloride dealkalization uses a strong anion exchange resin to replace bicarbonate, sulfate, ...
What is reverse osmosis?
Reverse osmosis (RO) and nanofiltration (NF) Reverse osmosis (RO) and nanofiltration (NF) are often used down the line in the boiler feed water treatment system process so most of the harmful impurities that can foul and clog the RO/NF membranes have been removed.
Boiler Water Treatment
It is because Scale formation and corrosion are the main two factors that determine the efficiency of the internal parts and as well as lifetime of the boiler. Badly corroded and scaled boiler can fail within very short time.
SCALE FORMATION IN BOILER
Depending upon the sources boiler water contains various types of salts and impurities. Under operating conditions all the salts comes out of the water. These salts cause formation of scale inside the boiler. The more the water contains solids and salts the more the boiler is prone to scale formation.
Boiler Water Treatment for Scale Formation
Boiler Water treatment for scale formation or Scale formation can be prevented in two ways.
What is coagulant ?
BOILER COAGULANT is a liquid sludge conditioner designed to prevent the formation of solid and sticky deposits in boilers.
Dosing instructions for boiler water treatment
Normal dosage is 20ml daily/tone of boiler water capacity. Typically this equates to 0.1-0.3 liters/day. This is the recommended initial dose.
2.What is corrosion?
Before starting corrosion we should first know basic terms related corrosion.
Corrosion of boiler metal
It is an electrochemical reaction of iron where corrosion occurs at cathode as the boiler metal oxidizes and dissolves.
Why is it important to treat boiler water?
Proper treatment of make-up waste and boiler water is necessary to prevent scale, or other deposits, and corrosion within the boiler. The absence of adequate external and internal treatment can lead to operational upsets or total boiler failure. Where a choice is available, pretreatment external to the boiler is always preferred ...
What is the pH of boiler water?
pH. The pH value of the boiler water is a number between zero and fourteen. Values below seven are acidic, seven is neutral, and values above seven are alkaline. The pH factor is the most important factor influencing scale formation and the corrosive tendencies of boiler water.
Why is aeration important in water?
Aeration of the city water supply is frequently used to remove other noxious gasses. Efficient aeration results in saturation of the water with oxygen. The majority of corrosion problems are directly related to the quantity of dissolved oxygen in the boiler water. Elimination of the corrosive effect of dissolved oxygen can be accomplished both ...
What is the pH of steel?
Below a pH of 5.0 the water is acidic enough to dissolve the steel boiler plates. Under these conditions the steel gradually becomes thinner and thinner until its destruction. At a pH between 5 and 9.4 pitting of shell plates will occur at a rate depending on the amount of dissolved oxygen in the boiler.
How to remove dissolved oxygen from water?
Direct or mechanical removal of dissolved oxygen is accomplished through the use of a deaerator or by heating the water to a temperature above 180 degrees F. Heating the water can be done with a preheater or sparge tube installed in the return system.
Why do boilers get oily?
Oil causes foaming, or combines with suspended solids to form a sludge which can cause the overheating of boiler plates. If oil does get into the boiler, the boiler should be taken out of service immediately and thoroughly cleaned.
What is sodium sulfite used for?
Sulfites. Sodium sulfite is generally used for the chemical removal of dissolved oxygen within the boiler water. To assure the rapid and complete removal of the oxygen entering the boiler feedwater system the concentration of sulfite in the boiler must be maintained at a minimum of 20 PPM (parts per million).
What happens if you carry over impurities from a boiler?
Carryover of excess impurities from the boiler can cause significant downstream problems. In units equipped with steam turbines, contaminant ingress may potentially lead to catastrophic conditions such as turbine blade cracking and subsequent failure.
What causes corrosion in boilers?
Corrosion in lower-pressure boilers is frequently the result of air ingress and dissolved oxygen concentration during unit downtimes.
What are the factors that affect steam?
Even with proper chemistry control, a variety of mechanical factors may influence boiler and steam system conditions, including: 1 Fluctuations in the boiler water level, which can either expose tubes to overheating or overwhelm steam separators and introduce contaminants. 2 Failure of a water/steam separator in the drum that allows excess moisture to enter the steam system. 3 Introduction of impurities directly to the steam via the attemperator system.
Our Boiler Water Treatment Approach
Nalco Water has helped thousands of customers globally with their boiler systems through automation, service, specialty chemistries, and equipment, to drive overall reduction of total cost of operation. We focus on customers in institutional, manufacturing, food & beverage, power generation, chemical, primary metals, paper, and mining.
Boiler Water Chemicals, Programs, Products, Equipment and Services
Explore our treatment offerings related to boiler and boiler chemical treatment management and maintenance.
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Why is boiler water treatment important?
Boiler Water Treatment is necessary to Producing quality steam on demand depends on properly managed water treatment to control steam purity, deposits and corrosion. There are two main types of boiler feed water treatment Internal boiler Water Treatment method and external boiler water treatment. A boiler is the sump of the boiler system. It ultimately receives all of the pre-boiler contaminants. Boiler performance, efficiency, and service life are direct products of selecting and controlling feedwater used in the boiler.
What is boiler system?
A boiler is the sump of the boiler system. It ultimately receives all of the pre-boiler contaminants. Boiler performance, efficiency, and service life are direct products of selecting and controlling feedwater used in the boiler. When BFW boiler feedwater enters the boiler, the elevated temperatures and pressures cause the components ...
How do deposits affect boilers?
Deposits in boilers may result from hardness contamination of feed water and corrosion products from the condensate and feedwater system. Hardness contamination of the feed water may arise due to a deficient softener system. Deposits and corrosion result in efficiency losses and may result in boiler tube failures and inability to produce steam. Deposits act as insulators and slow heat transfer. Large amounts of deposits throughout the boiler could reduce the heat transfer enough to reduce the boiler efficiency significantly. Different type of deposits affects boiler efficiency differently. Thus it may be useful to analyze the deposits for its characteristics. The insulating effect of deposits causes the boiler metal temperature to rise and may lead to tube-failure by overheating.
What is external treatment?
External treatment is used to remove suspended solids, dissolved solids (particularly the calcium and magnesium ions which are major causes of scale formation), and dissolved gases (oxygen and carbon dioxide).
What is the process of removing suspended solids from water?
The external treatment processes available are ion-exchange or demineralization process, RO reverse osmosis and Deaeration. Before any of these are used, it is necessary to remove suspended solids and turbidity from the raw water, because these may foul the resins used in the subsequent treatment sections.
Recommended Guidelines For Boiler Water Treatment
- Use proper water treatment to prevent the buildup of scaleon the boiler. After scale has built up on the walls of the boiler it is almost impossible to remove it from the boiler. The introduction of acids in the pressure vessel is thoroughly discouraged, since virtually any solution that will chemically attack the scale will also attack the boiler ...
Ph
- The pH value of the boiler water is a number between zero and fourteen. Values below seven are acidic, seven is neutral, and values above seven are alkaline. The pH factor is the most important factor influencing scale formation and the corrosive tendencies of boiler water. The pH should be maintained between a minimum of 10.5 and a maximum of 11.0 to prevent acidic corrosion of b…
Dissolved Oxygen
- Dissolved oxygen is caused by the solubility of atmospheric oxygen in the supply water. Aeration of the city water supply is frequently used to remove other noxious gasses. Efficient aeration results in saturation of the water with oxygen. The majority of corrosion problems are directly related to the quantity of dissolved oxygen in the boiler water. Elimination of the corrosive effec…
Sulfites
- Sodium sulfite is generally used for the chemical removal of dissolved oxygen within the boiler water. To assure the rapid and complete removal of the oxygen entering the boiler feedwater system the concentration of sulfite in the boiler must be maintained at a minimum of 20 PPM (parts per million).
Solids
- Solids can be broken up into two categories: suspended solids and dissolved solids. Suspended solids are those which can be removed by filtration while dissolved solids are in solution with the water. The best test for the determination of solids content of the boiler water is through a conductance test. The conductance value of boiler water varies by the various ionized salts pres…
Alkalinity
- The alkalinity of boiler water should be sufficiently high enough to protect shell and plates against acidic corrosion, but not high enough to produce carryover. A minimum value for alkalinity for adequate protection is 200 PPM. High boiler alkalinity, which is in excess of 700 PPM, should be avoided. Values higher than this can lead to embrittlement of the steel.
Phosphates
- Phosphates are used to react with calcium hardness in the boiler water. In order for this reaction to take place it is important to maintain a pH at a minimum value of 9.50. It is desirable to keep the concentration of phosphates in the water to 30 - 50 PPM in order for complete reaction of the phosphates with the calcium hardness entering the boiler through the feedwater.
Hardness
- The hardness of water is caused by calcium and magnesium ions which will vary greatly throughout the country depending on the source of the water. In boilers the hardness of the water can cause the formation of scale and sludge or mud. The hardness must be removed in the makeup water to the return system. Total hardness should not exceed 50 PPM.
Oils
- Every effort should be made to prevent oils from getting into the boiler water. Oil causes foaming, or combines with suspended solids to form a sludge which can cause the overheating of boiler plates. If oil does get into the boiler, the boiler should be taken out of service immediately and thoroughly cleaned. Pick your boiler, find a dealer near you, or contact ustoday to talk with a boil…