What is the principle of the deaerator of the boiler? 5

Vacuum deoxygenation works by applying Henry's law, according to Henry's law, in a closed container, any gas is present on the surface of the water at the same time, the solubility of the gas is proportional to its own partial pressure, and the solubility of the gas is only related to its own partial pressure. At a certain pressure, as the water temperature increases, the partial pressure of water vapor increases, while the partial pressure of air and oxygen decreases. At 100, the partial pressure of oxygen is reduced to zero, and the dissolved oxygen in the water is also reduced to zero.

When the pressure on the surface of the water is less than the atmospheric pressure, the solubility of oxygen can reach zero at lower water temperatures. In this way, the oxygen molecules in the space on the water surface are discharged, or converted into other gases, so that the partial pressure of oxygen is zero, and the oxygen in the water continues to escape to achieve the effect of oxygen removal.

According to Henry's law: the concentration of a certain gas dissolved in water is proportional to the partial pressure of the gas on the surface of the gas and liquid, if the water is heated to boiling, the surface of the gas and liquid is almost 100% water vapor, and at the same time, the original dissolved in the water and other gases such as oxygen will escape from the water, as long as the water is divided into small enough water droplets and the gas on the liquid surface is pumped out in time, the oxygen and other dissolved gases in the water can be removed, and the escaped gas will not be re-dissolved in the water. The deaerator heats the water (with steam) to the boiling point at this pressure, and continuously extracts the escaping gases to achieve the purpose of oxygen removal (in fact, the removal of all dissolved gases).

Principle of water seal device of atmospheric deaerator:

1) Before the deaerator is put into use, the outer sleeve of the water seal cylinder must be filled with water, so that the overflow nozzle connected to the overflow port of the deaerator in the outer sleeve is sealed by the water in the outer sleeve to ensure that it is not connected with the atmosphere, and the deaerator works in the saturation state of the degree to carry out thermal deoxygenation during normal operation, when the water level of the water tank rises more than the overflow port reaches the action value of the water seal cylinder, the water in the water seal cylinder is pressed out, and the excess water overflows through the overflow pipe of the outer sleeve to ensure that the water tank drops to the normal water level.

2) When the pressure in the deaerator rises and the water in the water seal device overflows, that is, the water seal device acts, first presses the water in the outer sleeve of the water seal device, and then discharges the overpressure steam from this channel, which plays a role in preventing the overpressure of the deaerator. There is a demineralized water pipe connected to the outer sleeve, which is used when the normal pressure is restored after the overpressure action of the water tank, because the water level in the water seal cylinder is discharged due to overpressure, the overflow port of the deaerator is connected to the atmosphere, and the steam will be emitted from the overflow pipe of the outer sleeve, and it must pass through the desalination water pipe at this time.

Supplementing upstairs, there is also Dalton's law of partial pressure.

The working principle of the deaerator is:The condensate and supplementary water first enter the water chamber of the inner spinning membrane group of the deaeration head, and spray obliquely from the small hole of the membrane tube to the inner hole under a certain water level difference pressure to form a jet, because the inner hole is filled with rising heating steam, the water will suck a large amount of heating steam into it in the jet movement (the test proves that the jet movement has the effect of coiling and suctioning);

In a very short period of time and a small stroke, the water temperature is greatly increased, and the rotating water continues to rotate down along the inner hole wall of the membrane tube, forming a tumbling water film skirt, (the critical Reynolds number of the water in the rotating flow decreases a lot, that is, turbulent tumbling), at this time, the water heat and mass transfer effect in the turbulent state is the most ideal, and the water temperature reaches the saturation temperature. The oxygen is separated, because the oxygen cannot be diffused at will in the inner hole, and the rising steam can only be discharged from the exhaust pipe to the atmosphere (although the old deaerator heats the water and separates the oxygen, the specific gravity of oxygen is greater than that of the heated steam, and part of the oxygen is brought into the water tank by the downstream water, which is also a reason for the poor deoxygenation effect).

The feed water that has been coarsely deoxygenated by the membrane section and the water introduced by the trap pipe are mixed here for secondary distribution, and fall into the liquid vapor net installed under it in a uniform rain-like manner, and then flow into the water tank after deep deoxygenation. The oxygen content of the water in the tank is 0-7 ɡ l at high pressure, and less than 15 ɡ l at low pressure, which meets the operating standard issued by the ministry.

The main function of the deaerator is to remove oxygen and other non-condensable gases in the boiler feed water to ensure the quality of the feed water. If oxygen is dissolved in the water, the metal in contact with the water will be corroded, and if there is gas accumulation in the heat exchanger, the thermal resistance of heat transfer will increase, and the heat transfer effect of the equipment will be reduced. Therefore, any gas dissolved in the water is unfavorable, especially oxygen, which will directly threaten the safe operation of the equipment.

Thermal deoxygenation is used in thermal power plants, and the deaerator itself is a hybrid heater in the feed water recuperation system, and at the same time, the hydrophobic, chemical water replenishment of the high-pressure heater and the high-pressure hydrophobic and exhaust steam with qualified water quality in all parts of the plant can be fed into the deaerator for utilization, so as to reduce the loss of steam and water in the power plant.

The deaeration equipment is mainly composed of two parts, the deaeration tower head, the deaeration water tank, and the pipe and external parts, and its main components, the deaerator (deaeration tower head) is composed of the shell, the steam separator, the new type of membrane spinner, the water grate, the heat storage packing liquid vapor network and other components. The following is an introduction to the structural principle of the deaeration tower head.

1.Shell: It is welded by barrel body and stamped oval head. The medium and small low-pressure deaerators are equipped with a pair of flange connections for assembly and maintenance, and the high-pressure deaerator is equipped with a manhole for maintenance.

2.Soda separator: This device replaces the straw hat cone structure design in the original old deaerator, so that the deaerator eliminates the phenomenon of exhaust steam with water.

3.Rotary membrane group: It is composed of a water chamber, a steam chamber, a rotary tube, a condensate pipe, a supplementary water pipe and a primary steam inlet pipe.

Condensate, chemical water replenishment, spiral sprayed out at a certain angle through the film spinner, forming a water film skirt, and heat exchange with the heating steam introduced by a heating steam to take over, forming a deoxygenation, the feed water is heated to a saturation temperature close to the working pressure of the deaerator that is lower than the saturation temperature 2-3, and crude deoxygenation is carried out. Generally, about 90-95% of the oxygen content in the feed water can be removed through this rotary membrane section.

4.Water grate: It is composed of several layers of staggered angular steel, and the feed water that is coarsely deoxygenated through the rotating membrane section is redistributed here, and falls to the liquid vapor net installed under it in the form of uniform rain.

5.Regenerative packing liquid vapor mesh: It is composed of flat steel strips and a cylindrical body, which is equipped with a certain height of special stainless steel wire mesh, where the feed water is in full contact with the secondary steam, heated to saturation temperature and carried out deep deoxygenation, low-pressure atmospheric deaerator is less than 10ug l, high-pressure deaerator is less than 5ug l (ministerial standards are 15ug l, 7ug l).

6.The feed water of the water tank deoxygenation is collected into the lower container of the deaerator, that is, the water tank, and the deoxygenation water tank is equipped with the latest scientific design of the powerful heat exchange and re-boiling device, which has the advantages of strong heat exchange, rapid increase of water temperature, deeper deoxygenation, reduction of water tank vibration, reduction of accent, etc., which improves the service life of the equipment and ensures the safety and reliability of the operation of the equipment.

The main function of the deaerator is to use it to remove oxygen and other gases in the boiler feed water and ensure the quality of the feed water. At the same time, the deaerator itself is a hybrid heater in the feedwater recuperation heating system, which plays the role of heating the feedwater and increasing the temperature of the feedwater.

The principle of the deaerator is that the water is sprayed out in a spiral shape through the membrane pipe at a certain angle for heat exchange and deoxygenation, and the feed water is heated to the saturation temperature under the corresponding working pressure of the deaerator, so as to remove the oxygen and other gases dissolved in the feed water, and prevent and reduce the corrosion of the boiler feed pipe, economizer and other auxiliary equipment.

The deaerator is one of the key equipment of the boiler and heating system, if the deaerator has poor deaeration capacity, it will cause serious losses to the corrosion of the boiler feed water pipeline, economizer and other ancillary equipment, and the economic loss caused will be dozens or hundreds of times the cost of the deaerator.

1.Oxygen removal. 2.Heater.

3.It is used as a water tank to collect condensate and other incoming water to ensure the amount of water supplied to the boiler.