Technical solutions for boiler water treatment

the technical solution of boiler water treatment
the water source of industrial boiler water is generally tap water and groundwater, these seemingly clear and transparent water, but there are many impurities, they will produce heat conductivity in the process of the boiler, and corrosion of boiler metal, seriously endanger the operation of the boiler

Industrial boiler water treatment is designed to remove these harmful impurities from the water or to avoid the harm they cause to the boiler



boiler water treatment mainly includes the treatment of recharge water (i.e., boiler supplementary water), condensation water (i.e., condensation water from steam turbine condensation or process recovery), water deoxygenation, ammonia supply and pot-replenishing treatment

four

parts



,

boiler water treatment

---
resupply water treatment

due to steam use (heating or power generation) and condensate recovery degree, the boiler supply water volume is not the same

The supply water of the boiler of the coagulation power station is generally less than 3% less than the evaporation amount, and the supply water of the heating boiler can be as high as 100%

The replenishment water treatment process is as follows:



(1) pretreatment: When raw water is surface water, the purpose of pretreatment is to remove suspended substances, colloids and organic matter from the water

Usually in the raw water to add coagulants (e.g

aluminum sulfate, etc.) so that the above impurities condensed into large particles, from the weight and sink, and then filtered into clean water

When water is replenished with groundwater or urban water, the pretreatment of raw water can be eliminated and filtered only

Commonly used clarification equipment includes pulse-type, hydraulic acceleration and mechanical stirring clarifiers, and filtration equipment includes siphon filter cells, valveless filters and single- or dual-flow mechanical filters

In order to further remove organic matter from the water, an activated carbon filter can also be added



(2) softening: the use of natural or artificial ion exchanger, calcium, magnesium hard salt into a salt without hard scale, to prevent the boiler tube inner wall into calcium magnesium hard scale

Water with calcium-magnesium heavy carbonate and high alkalinity can also be solved by hydrogen-sodium ion exchange or in pretreatment (e.g

lime plus, etc.)

For some industrial boilers, such treatment is usually sufficient, although the salt content of the water is not necessarily significantly reduced



(3) De-salting: With the continuous improvement of boiler parameters and the emergence of DC boilers,

if the

requires the boiler to all salt in the water are de-cut

At this point
to

to use the method of de-salting

Chemical desalting uses a variety of ion exchange agents, the use of

z
common is the cation exchange resin and anion exchange resin, referred to as "yang resin" and "yin resin." In an ion exchanger, when salt water flows through the resin, the cations and anions in the salt are removed after they are transformed with the cations (H-plus) and anions (OH-) in the resin, respectively



When the alkalinity of water is high, in order to reduce the burden of anion exchanger and improve the economics of system operation, after the cation exchanger is generally required to series decarbonators to remove carbon dioxide

Water with a particularly high salt content can also be reverseostomebic or electrodialysis process, first to dilute water quality, and then into the ion exchanger for deep de-salting

For boilers or DC boilers with high pressure or above, trace amounts of silicon in the water must also be removed, while medium and low-pressure boilers must be treated according to the content



second,

boiler water treatment

---
condensation water treatment



condensate in the cycle process, will be caused by the turbine condenser cooling water leakage and system corrosion products caused by pollution, and sometimes need to be treated

The typical process is related to the amount of condensate handled and the contamination of the boiler parameters, furnace type (e.g

whether there is a pot or separator) and condensate

With the improvement of boiler parameters, the treatment of condensate generally increases gradually

The supercritical pressure boiler should be treated in full, the treatment volume of ultra-high pressure and subcritical pressure boiler is 25 to 100%, and the boiler below pressure with the pot is generally not treated

Commonly used condensed water treatment equipment include cellulose cover filters and electromagnetic filters

Condensate in which the corrosion products (copper oxide, iron oxide, etc.) are removed, and then into the mixing bed or powder resin cover filter for deep desalting



third,

boiler water treatment

---
water supply water deoxygenation



the dissolved oxygen in the boiler water will corrode the thermal system of the metal

Corrosion products form copper iron scale at higher thermal loads of boilers, which makes heat transfer worse and even causes burst pipes or deposits in high-pressure cylinders of steam turbines, reducing turbine efficiency

Therefore, after softening or de-salting the recharge of water and condensate, before entering the boiler is generally deoxygenated

Common methods of deoxygenation are thermal deoxygenation and vacuum deoxygenation, sometimes supplemented by chemical deoxygenation

The so-called thermal deoxygenation, that is, when the water is heated in the deoxygenator to boiling, the solubility of the gas in the water is reduced, so that the gas escapes from the water and discharges into the atmosphere

According to the operating pressure, the use of more thermal deoxygenators has 0.12 mPa and 0.6 mPa

When thermal deoxygenation, the water must be heated to a saturated temperature, and the surface area of the deoxygenation water should be large (e.g

with a dorsesome or atomized dispersal device) so that the escaping gas can be discharged quickly

Vacuum deoxygenation is often carried out in a steam turbine condenser

Chemical deoxygenation is the addition of hyphenyl or sodium sulphate to the water to further reduce the oxygen content in the water



four,

boiler water treatment

---
ammonia and pot-replenished treatment



after resupply water treatment, condensation water treatment and water deoxygenation boiler water supply, generally requires the addition of ammonia or organicamine to improve the pH of the water supply, to prevent acidic water corrosion of metal parts

Boilers with pots are generally handled in pots

When treated, add trisodium phosphate or other chemical agents to the pot to turn salt impurities in the water that can form scale into sludge that can be discharged during sewage discharge to prevent or slow down the formation of scale





The general trend of boiler water treatment

:



(1) With the rapid development of the chemical industry, chemical desalting is more and more widely used to improve the quality of boiler water supply

(2) The development of a variety of high-capacity, high-flow and high-efficiency new water treatment equipment, in order to reduce the investment and operating costs of water treatment equipment

(3) Improve the degree of automation of water treatment equipment