Characteristics of boiler feed water
| Oily matter | mg/l | absence | absence | 0.05 |
| pH | > 8.5 | > 8.5 | > 8.5 | |
| TotalIron | mg/l | not specified | not specified | 0.05 |
| Total copper | not specified | not specified | not specified | 0.03 |
What will happen if pH value increases in a boiler?
pH Treatment
- Introduction. Acidic and basic (alkaline) are two extremes that describe chemicals, just like hot and cold are two extremes that describe temperature.
- Boiler pH. Natural water is usually between 6.5 and 7.5 pH. ...
- Controlling pH. ...
- pH Related Corrosion. ...
- More Information
How to control pH value of a boiler?
pH is controlled by either removing water impurities or adding other chemicals to neutralize the condition. For example, Caustic Soda, an alkaline, is added to neutralize CO3, carbonic acid. When the boiler water pH drops below about 8.5, a corrosion called acid attack can occur.
Which boiler is the best boiler?
The best combi boilers for 2 bed homes
- Worcester Bosch 2000 25kW combi boiler. This new entry-level Worcester Bosch Greenstar 2000 combi boiler has a range of great features and comes in two different sizes, making it suitable ...
- Viessmann Vitodens 050-w 25kW combi boiler. ...
- Alpha E-Tec 28kW combi boiler. ...
- Ideal Logic C24 combi boiler. ...
What is the normal psi for a boiler?
What is the correct pressure for a boiler? While not every boiler has the same pressure requirements, most central heating systems perform within the range of 1 to 2 bar, which is between 14 and 29 pounds per square inch (psi).
What is the normal pH of boiler water?
between 6.5 and 7.5 pHBoiler pH. Natural water is usually between 6.5 and 7.5 pH. A common recommendation is to maintain boiler water at 8.5 pH.
What happens if boiler pH is too high?
The correct pH measurement is essential to water treatment: pH too high or too low can lead to boiler or steam turbine scaling and corrosion, system failures, and downtime, as well as the costly replacement of equipment.
What does pH mean on boiler?
BOILER pH is a specifically designed blend of chemicals used for Boilers to adjust the pH of your system. The boiler's operational pH depends on the boiler pressure, system metals, feed water quality and type of chemical treatment in use and is generally dictated by the water's p-Alkalinity.
What is the pH of boiler blowdown?
Table 13-2. Suggested water quality limitsa.Drum Operating Pressureb, MPa (psig)Total iron (mg/L Fe)0.1000.020Total Copper (mg/L Cu)0.0500.015Total Hardness (mg/L CaCO3)0.3000.100pH range at 25° C7.5-10.08.5-9.511 more rows
What is the disadvantage of using high alkaline water in boiler?
Some examples of negative side effects include the lowering of natural stomach acidity, which helps kill bacteria and expel other undesirable pathogens from entering your bloodstream. Additionally, an overall excess of alkalinity in the body may cause gastrointestinal issues and skin irritations.
How do I lower the alkalinity in my boiler water?
The alkalinity can be removed and/or decreased in several ways:Acid feed (if the company is prepared to handle acid);Degasifier;Lime-soda softening;Hydrogen cycle ion exchange/soft water split-stream makeup; and.Dealkalization with strong base anion ion exchange resin.
How do I raise the pH level in my boiler?
This product is recommended for raising boiler water internal pH where the natural feedwater alkalinity or cycles of concentration are low. Hydroxide concentration is directly elevated to promote boiler internal softening and control of corrosion....Product Data.Specific Gravity (SG)1.35pH of product14
What is boiler alkalinity?
Alkalinity is a key control parameter for boilers (outside of the prescribed operating range, it can lead to corrosion, caustic metal embrittlement, and carryover) and cooling water systems (where it has a significant effect on chemical treatments for scale and corrosion inhibition).
Why water is alkaline in boiler?
It comes into play with steam boilers because a pH between 7 and 9 (slightly alkaline) is just right. If the pH is lower than that, the water will start eating the pipes. If it's higher than that, the water won't corrode metal, but it may begin to foam, and that's not good. Hold that thought for a moment.
What causes low pH in condensate?
There is a natural tendency for condensate to be acidic (pH 6.9 – 4.4). Low pH can damage carbon steel piping systems. This low pH is caused by carbon dioxide (almost always present) reacting with the water to form carbonic acid (similar to acid rain) as the steam condenses.
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.
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.
Why should representative samples of feedwater and boiler water be analyzed frequently?
Representative samples of feedwater and boiler water must be analyzed frequently to ensure they are in specification. The following terms and guidelines are to be used in conjunction with the advice of a water treatment specialist.
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 causes corrosion in boiler water?
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 directly and chemically.
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 ...
Is chloride a good test for feedwater?
The chloride test is unsuitable for feedwater with low incoming concentrations and the concentrations in the feedwater must be averaged over time for accuracy. High boiler solids will lead to foaming, priming, surging and carry over. These problems can be overcome by proper, daily blowdown of the boiler.
What does the number mean in a steam boiler?
The number refers to the relative concentration of hydrogen (acid) and hydroxide (base) ions in solution. Gosh, I’m such a scientist. It comes into play with steam boilers because a pH between 7 and 9 (slightly alkaline) is just right. If the pH is lower than that, the water will start eating the pipes. If it’s higher than that, the water won’t ...
What chemicals did the Dead Men use to adjust the pH of a building?
The classic, off-the-shelf chemicals the Dead Men used to adjust pH were baking soda and vinegar. Vinegar is slightly acidic (low pH), and baking soda is slightly alkaline (high pH).
Why does fresh water boil?
The challenge starts when the water boils because carbonates and bicarbonates break down and leave the boiler as carbon dioxide. This gas flows through the system with the steam, and if you’re not venting the system well, ...
Why do you have to keep an eye on the pH of your water?
And even if you fix the leaks in the system, you still have to keep an eye on the pH of the water because many people add chemicals to their boilers to avoid corrosion. These chemicals shove the pH toward the alkaline side of the scale. When the pH reaches 10, corrosion becomes impossible. That’s what makes chemical drain cleaners safe for pipes.
What does Henry's law say about water?
Henry’s Law tells us that gases dissolve in liquids in direct proportion to pressure and temperature. So the colder the water, the more oxygen it will contain. That oxygen comes out of solution as the water boils, and it can eat holes in the boiler, right at the boiler’s waterline. If you decide to feed with hot water instead of cold water, ...
Does steam boiler water corrode metal?
If it’s higher than that, the water won’t corrode metal, but it may begin to foam, and that’s not good. Hold that thought for a moment. You’re on a job and you have a steam boiler that’s taking on a lot of feed water because the system has leaks.
Do steam boilers reuse water?
But steam boilers that do only space heating reuse nearly all of the water because the condensate returns to the boiler from the piping and radiators.
What is the standard PH of boiler water?
From 10.00 to 12.00 is the standard PH of boiler water, once the PH is above is standard> 12. It means that the Utility Team (Engineers, Technicians) will have to blow the boiler down, same applies to the phosphate content and iron content of the boiler water.
What is the pH of a steam boiler?
The safe pH range for steam boilers is between 8.5pH & 12.7pH, whilst the recommended level is between 10.5pH & 12.0pH.
Why do boilers need feedwater treatment?
The need for boiler feedwater treatment is therefore required to prevent scale forming on the heat transfer surfaces and to prevent water side corrosion. The treatment should be monitored and adjusted relative to the actual steam evaporation rate throughout the course of the day.
What determines the pH of a boiler?
The boiler’s operational pH depends on the boiler pressure, system metals, feed water quality and type of chemical treatment in use and is generally dictated by the water’s p-Alkalinity.
Why do steam boilers overheat?
Modern Steam Boilers both that in the marine and industrial environment have a high heat transfer rate when new and as such produce steam at a economically effective rate, however, impurities in the feedwater can cause scale or chemical deposits to form and reduce the rate of that ideal heat transfer from the tube walls to the water, thus causing overheating of the metal surfaces whilst also reducing the steam output.
What are the problems with boilers?
Find information about the main problems occurring in boilers: scaling, foaming and priming, and corrosion.
Why is water an ideal raw material for heating and power generating processes?
It expands 1600 times as it evaporates to form steam at atmospheric pressure. The steam is capable of carrying large quantities of heat. These unique properties of water make it an ideal raw material for heating and power generating processes.
How much water is dissolved in water?
All natural waters contain varying amounts of dissolved and suspended matter and dissolved gases the amount of minerals dissolved in water varies from 30 g/l in sea water to anything from 0.005 to 1500 mg/l in fresh water supplies .
Can boiler feed water be pretreated?
If the feed water does not meet these requirements it must be pretreated to remove impurities. The impurities need not be completely removed in all cases, however, since chemical treatment inside the boiler can effectively and economically counteract them.
How much water is safe to use in a boiler?
As water is turned to steam, the solids remain behind. Unless there is 100% condensate return, the solid content tends to build up. As a rule of thumb, about 1000 ppm can be considered a safe maximum. A hard water containing 200 ppm in the feedwater would tolerate five concentrations in the boiler (200 times 5 = 1000).
What are the elements that are harmful to a steam boiler?
In a steam boiler system, there are three potentially destructive elements: oxygen, carbon dioxide, and solids . 2.2.2 As the boiler water is heated and changes to steam, free oxygen is released, carbon dioxide is released from the solids, and the solids drop out (precipitate).
How to eliminate dissolved oxygen in boiler?
3.2.2 Dissolved oxygen can be eliminated in a boiler system by utilizing a deaerator feed tank, heated feedwater, or treating the feedwater in the condensate tank. Introducing an oxygen scavenger into the feedwater system will also help eliminate any dissolved oxygen in the feedwater.
How many pounds of solids are in 1,000,000 pounds of lake water?
Lake water has approximately 180 ppm of dissolved solids. 1,000,000 pounds of this water will contain approximately 180 pounds of solids. A 100 hp boiler vaporizing 3,450 pounds of this as make-up water would leave behind 0.62 pounds of solids.
What does it mean when iron laden condensate leaks out of the boiler?
2.2.5.1 If iron-laden condensate leaks out of the system in route to the boiler, it usually will form an orange stain on the floor or other equipment. When observed, this stain is an indication that water treatment control practices should be reviewed.
Is feedwater soluble in water?
4.3.2 As more feedwater is introduced to the pH 11 boiler water, the feedwater dissolved solids are not soluble and tend to drop out of solution (precipitate) to form suspended solids.
What is the temperature of a hot water boiler?
Hot water boilers heat and circulate water at approximately 200°F. Steam heating boilers are used to generate steam at low pressures, such as 15 psig. Generally, these two basic heating systems are treated as closed systems, because makeup requirements are usually very low.
What is a boiler made of?
Most industrial boiler and feedwater systems are constructed of carbon steel. Many have copper alloy and/or stainless steel feedwater heaters and condensers. Some have stainless steel superheater elements.
What is a feedwater heater?
Feedwater heaters are generally classified as low-pressure (ahead of the deaerator), high-pressure (after the deaerator), or deaerating heaters.
Why is galvanic corrosion common in boilers?
The most common type of galvanic corrosion in a boiler system is caused by the contact of dissimilar metals, such as iron and copper . These differential cells can also be formed when deposits are present. Galvanic corrosion can occur at welds due to stresses in heat-affected zones or the use of different alloys in the welds. Anything that results in a difference in electrical potential at discrete surface locations can cause a galvanic reaction. Causes include:
What causes a boiler to evaporate?
Porous metal oxide deposits also permit the development of high boiler water concentrations. Water flows into the deposit and heat applied to the tube causes the water to evaporate, leaving a very concentrated solution. Again, corrosion may occur. Caustic attack creates irregular patterns, often referred to as gouges.
What happens when a steam layer forms between the boiler water and the tube wall?
However, as long as a high caustic concentration exists, the magnetite is constantly dissolved, causing a loss of base metal and eventual failure (see Figure 11-2). Steam blanketing is a condition that occurs when a steam layer forms between the boiler water and the tube wall.
Where does corrosion occur in a boiler?
Many corrosion problems occur in the hottest areas of the boiler-the water wall, screen, and superheater tubes. Other common problem areas include deaerators, feedwater heaters, and economizers. Methods of corrosion control vary depending upon the type of corrosion encountered.
Recommended Guidelines For Boiler Water Treatment
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...
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…