I. Product Applications and Advantages

The deaerator is one of the key equipment in boilers and heating systems. The severe losses caused by oxygen corrosion to the boiler feed water pipes, economizers, and other auxiliary equipment annually have drawn increasing attention from the National Power Department. The department has issued the GB1576-2001 "Water Quality Standard for Industrial Boilers" and the "Safety Supervision Regulations for Pressure Deaerators in Power Stations," which set departmental standards for oxygen content in deaerators, i.e., the oxygen content in feed water for low-pressure deaerators should be less than 15 μg/L, and for high-pressure deaerators, less than 7 μg/L.

The heat transfer, mass transfer methods, and deoxygenation capacity of the spiral membrane deoxygenator differ from those of the existing spray and spray plate deoxygenators. It is a new type of thermal deoxygenator, which has won the Science and Technology Innovation Award for New Technology and New Products from the Power Ministry and is listed as a key promotion product by the Power Ministry. The spiral membrane deoxygenator has been proven to have the following advantages after use:

High deoxygenation capacity; after deoxygenation, the water meets the oxygen content qualification rate of one hundred percent.

2: Operation is stable with no vibration. Suitable for vacuum start-up and sliding pressure operation, reducing the need for complex manual adjustments during start-up and operation.

3: High adaptability; not stringent requirements for water quality and temperature; can operate beyond capacity by 50% for short periods.

4: Steam volume less than 0.1% of the inlet water volume; no additional exhaust cooler required. Optimized equipment reduces heat consumption, with energy savings of 1/3 compared to other types of the same output thermal deaerators.

II. Technical Specifications and Matching Parameters

CYG Series New Type Pressure Oxygen Remover

Section 3: Structure and Principle (Illustration Included)

The structure of the rotary film oxygenator consists of the deoxygenation head and the water tank. The deoxygenation head is composed of the outer shell, the rotary film assembly, the water grating, the liquid-gas mesh, the steam distribution plate, and the steam-water separator, which are the six main parts. The water tank is made up of the main body and its accessories.

1. Housing: Welded from the cylinder body and stamped elliptical end caps.

2. Membrane Assembly: Comprising a water chamber, film-forming tube, condensate connection, and make-up water connection. Both the film-forming tube and the drain pipe are made of stainless steel, requiring no maintenance throughout the year. It is also a major component of the rotating film deaerator, where 98% of the oxygen is removed.

3. Drip Grating: The water supplied for oxygen removal in the film-forming section and the condensate introduced from the drain pipes are here subjected to flow reduction and secondary distribution, allowing the water to fall in a uniform drizzle pattern, thereby protecting the lower liquid-vapor network. The grating's open area is not less than 50% of the total cross-section. Made of stainless steel, it operates continuously without the need for maintenance.

4. Filling Liquid-Vapor Mesh: Composed of spaced flat steel strips and a cylindrical body, it houses two layers of specially designed 0.3mm thick stainless steel O-shaped mesh. Here, water comes into full contact with the secondary steam, heating it to saturation temperature and performing deep deoxygenation to ensure the oxygen content of the deoxygenated water.

5. Steam Distribution Plate: The main heating steam is introduced here, and the uniform distribution structure ensures excellent heating quality, making the heating steam uniformly distributed. It rises to heat the softened water without throttling, working at saturated temperature for deaeration.

6. Air-Water Separator: Composed of stainless steel filling, the inner network is designed with a ventilation-type structure, which effectively separates and returns the water carried by the exhaust gas during oxygen排放, an indispensable component to ensure exhaust gas is water-free.

7. Water Tank: Consists of a cylinder body and a welded stamped elliptical end cover, internally fitted with reinforcing rings. The base is fixed to a prefabricated workbench, with one end fixed and the other for installing the expansion roller assembly. The tank is equipped with a manhole for maintenance, safety valve connection ports, drain outlets, boil-over pipe openings, water seal cylinder openings, level gauge interfaces, pressure gauge openings, temperature gauge openings, and water intake ports.

Deaerator Thermal Deaeration Basic Principle: In a container, the amount of gas dissolved in water is proportional to the partial pressure of the gas above the water surface. The main method of thermal deaeration is to use steam to heat the feedwater, raising its temperature and gradually increasing the partial pressure of steam above the water surface, while decreasing the partial pressure of dissolved gases. This causes the dissolved gases to continuously escape. When the water is heated to the boiling temperature at the corresponding pressure, the surface is entirely steam, the partial pressure of dissolved gases is zero, and the water no longer has the ability to dissolve gases, meaning that gases dissolved in the water, including oxygen, can be removed. The effectiveness of deaeration depends on whether the feedwater is heated to the boiling temperature at the corresponding pressure and on the rate of dissolved gas expulsion, which is greatly related to the contact surface area between water and steam.

Principle of operation for the rotary vacuum degasser (jet, entrainment, turbulence, heat transfer, mass transfer, water film skirt, rain-like, saturated)

Condensate and make-up water first enter the water chamber of the internal spiral membrane assembly in the deaerator, and under a certain differential pressure of water level, they are obliquely spun from the small holes of the membrane tubes towards the inner cavity, forming a jet. Due to the inner cavity being filled with rising heated steam, the water in the jet motion draws in a large amount of heated steam (experiments prove that the jet motion has an entrainment effect); this results in a violent mixing and heating effect over an extremely short distance, significantly increasing the water temperature. The rotating water continues to spiral down along the inner wall of the membrane tube, forming a swirling water film skirt (the critical Reynolds number of water in rotational flow decreases significantly, causing turbulent churning). At this point, the turbulent state of the water achieves the most ideal heat transfer and mass transfer effects, reaching the saturation temperature. Oxygen is then separated out, as it cannot freely diffuse within the inner cavity and can only be carried upwards with the steam through the exhaust pipe and released into the atmosphere. The feed water from the demisting section of the coarse deaerator and the condensate introduced through the drain pipes mix here for a secondary distribution, falling in a uniform rain-like pattern onto the liquid-vapor net below, before undergoing deep deaeration and then flowing into the water tank. The oxygen content in the water within the tank is at high pressure 0-7 μg/L and at low pressure less than 15 μg/L, meeting the departmental operational standards.

Due to the oxygen removal unit's constant turbulence of water during operation and its ample heat exchange surface area, the better the heat transfer and mass transfer efficiency, the smaller the exhaust gas volume (meaning less steam used for heating, resulting in lower energy loss and significant economic benefits). The excellent oxygen removal effect allows for the unit to operate beyond its capacity (usually up to 50% over the rated output) or to meet operational standards under low water temperatures with full make-up water.

4. Installation, Operation, and Maintenance

1. The installation, operation, and maintenance of deaerators, water tanks, and accessories should be carried out according to the CYD(G) type deaerator system diagram and the "Safety Supervision Regulations for Deaerators in Power Stations."

2. The deaerator should be placed above the feed pump, with the difference in height between the lowest water level of the deaerator tank and the centerline of the feed pump not less than 6 to 7 meters. The bottom plate of the tank support should be in firm contact with the concrete.

3. Install temperature transmitters and flow sensors on the deaerator's inlet water pipe, and a water level transmitter on the deaerator. Monitor signals such as incoming water temperature, flow rate, and deaerator water level, and input these signals to the calculation processing module. This controls the hydraulic and thermal conditions of the deaerator's incoming water and heating steam for optimal deaeration. It ensures the deaeration temperature is maintained at 104±1.5°C. Adjust the electric actuator regulating valve installed on the steam pipe to control the steam flow, which automatically adjusts based on the incoming water temperature. After topping up is complete, the electric actuator automatically shuts off.

4. The bottom of the water tank is equipped with a reboiling tube, which is used for heating and deoxygenation during the boiler's water filling and unit startup. For the first use, when the water level in the tank exceeds half, slowly open the reboiling heating tube valve at the bottom of the tank to heat the water inside, maintaining a boiling state of the water in the tank. The unit should stop being used once it starts up with a load. Additionally, a anti-rotation plate is installed at the outlet tank opening to prevent water whirl at low water levels, thereby increasing the effective volume of the tank. Tests have proven that water whirl has a significant impact on pump cavitation. Without an anti-rotation plate, the water level in the tank must be maintained at three times the pipe diameter, while with the plate, it can be reduced to below 1.5 times.

5. After the deaerator and water tank are field-welded, a hydrostatic test should be conducted. The pressure parameters for the hydrostatic test are: 0.2Mpa for atmospheric deaerators and 0.75Mpa for pressure deaerators. Prior to feeding into the deaerator, the condensed steam should be accumulated in the intermediate storage tank as much as possible, and then evenly delivered to the deaerator to ensure stable deaerator load.

6. Protection and Alarm for the Rotating Membrane Oxygen Remover

(1) Sufficient full-blow safety valves are installed on the water tank and deaerator, with the number and specifications meeting the design technical specifications.

(2) Oxygen Remover with Rotating Membrane should be equipped with local and remote water level gauges, and have high and low water level alarms, as well as safety high and low water level operation devices. The control of oxygen remover water level changes: when the water level decreases, the softening pump (condensate pump) is automatically started to replenish water to the oxygen remover; when the water level rises, the pump automatically stops.

7. To start the deaerator in cold condition, it is advisable to preheat the shell with auxiliary steam for 10-15 minutes first. Under a certain steam pressure, feed the demineralized water into the deaerator head while adjusting and increasing the steam inlet valve to heat the feedwater in the film formation section to a temperature close to the gas saturation temperature for the deaerator's operating pressure (i.e., 102-104℃).

8. Adjust the water level control system to maintain the water level in the water tank within ±100mm of the normal level. (When both deaerators need to operate in parallel, to balance the pressure and water level inside the deaerators, each deaerator must have a connecting pipe for steam and water balance. Aim to keep pressure, water temperature, and water level as consistent as possible.) When the water level reaches ±200mm of the normal level, the high-level drain valve (electromagnetic gate valve) should be able to open freely to drain water, and should automatically close when the water level decreases. During operation, it is important to frequently check the responsiveness of the electromagnetic water level control system and the responsiveness of the makeup water regulating valve.

9. Gently open the top exhaust valve, open the valves on the steam pipeline, supply steam for heating, and record the steam pressure and temperature. Adjust the exhaust valve to be generally open to about 2/3, so that the exhaust flow is approximately 2-3 kg per ton of deoxygenated water.

10. When the deaerator is in operation, the inlet valve should be opened first, followed by the steam inlet valve. When shutting down, do the opposite.

12. When operating the deaerator, if water in the exhaust steam is observed, the following methods can be employed to address the issue:

Adjust the heating steam inlet valve

b. Inspect pressure adjustment device

c. Manual pressure reduction operation

d. Gradually close the secondary heating steam cutoff valve.

13. Test the oxygen content of the water in the sampling tank to ensure compliance. If it does not meet the standard, adjust the water inflow, air inflow, and exhaust gas flow to achieve compliance. Once this is done, water can be supplied to the boiler.

14. Regularly test the oxygen content of the incoming and outgoing water at set intervals, record the readings of various monitoring instruments, to ensure the normal operation of the deaerator.

15. Cautionary Notes

a. When the degasser experiences severe vibration and water ejection, water hammer has occurred. Reduce the water inflow accordingly.

b. During operation, it is crucial to ensure that the pressure inside the deaerator does not drop sharply, and a vacuum should not be created.

c. In case of short-term shutdown, prevent the deaerator from forming a vacuum or being filled with air. Gently open the bypass steam valve to introduce a small amount of steam, maintaining a heated state within the deaerator head, and expel a trace of steam from the air exhaust.

d. Regular inspections of the deaerator should be conducted to prevent nozzle clogging, packing corrosion or compaction, and instrument failure.

e. If the deaerator is out of service for an extended period, the water in the tank should be drained to prevent corrosion of the vessel.

Five. Oxygen Remover General Accessories

·Safety Valve --- Installed on the water tank, the safety valve automatically opens to relieve pressure when the internal pressure of the equipment exceeds the allowable limit, serving as a safety protection.

· Pressure Gauge --- Installed at the top of the deaerator, monitoring the pressure inside the equipment.

Thermometer — installed below the water tank, monitoring the water temperature inside the tank.

· Butterfly valve --- Installed in the heating steam piping, it adjusts the flow of heating steam with the aid of an automatic regulator to maintain the pressure inside the deaerator within the rated range.

· Water-seal pipe --- When the liquid level rises, the pressure difference exceeds the pressure of the water column, causing the balance to be disrupted, and the liquid flows out through the water seal. It also acts as a pressure relief when the operating equipment's air pressure exceeds the safe limit.

· Stop valve --- Installed on the replenishment pipe, it adjusts the flow of make-up water with the help of an electric water level control system to maintain the normal water level of the tank.

·Adjustable valve—mounted on the topping-up pipe, it adjusts the flow rate of the topping-up water using an electric water level control system to maintain the normal water level of the tank.

·Electrical Contact Level Monitoring --- Consists of a sampling electrode point, an electrical contact level monitor cylinder (primary instrument), ultra-pure ceramic electrodes, and a display instrument (secondary instrument). Installed on a water tank, it monitors the water level inside the tank and outputs a 4-20mA signal to the control room to regulate the water level valve.

· Magnetic Float Level Gauge --- Installed on the water tank for on-site monitoring of the water level inside, also capable of connecting remotely and outputting a 4-20mA signal to the control room to adjust the water level valve.

·Balanced Vessel — Used in conjunction with pressure/pressure difference transmitters and level gauges, it can reflect the water level (weight) of the deaerator during boiler startup, shutdown, and normal operation.

·Electromagnetic Gate Valve --- Installed on the water tank drain pipeline, it automatically opens when the water level in the tank exceeds a certain limit, utilizing the electric water level control system to discharge the excess water above the limit into the drain tank.

·Pressure Automatic Regulator --- Automatically adjusts the opening of the heating steam inlet valve, regulating steam flow while maintaining stable pressure inside the deaerator.

· Electric Water Level Regulation System --- Automatically adjusts the flow of supply water and controls the overflow valve (electric gate valve) at the maximum water level.

Section 6: Order Provision Data

1: Oxygenator output (T/H) and equipped water tank effective volume (m³).

2: Oxygen removal unit operating pressure, temperature...

3: Only provide the installation connection diagram for the original deaerator tower, replacing the deaerator tower.

7. Renovation

Our factory not only supplies the complete set of new water film deaerator but also undertakes the renovation of deaerators for power plants involving spray plate and spray packing deaerators. Specifically, this includes:

Low改造cost, approximately half the price of replacing the deaerator head.

2. Fast progress, easy to process and on-site modification installation. Utilize the original deaerator head's shell section, remove all the spray tray or spray packing components inside the original deaerator head, retain the lower steam inlet disk, then install a liquid-gas mesh and a water grate at a certain position above the lower steam inlet disk. Finally, seal and secure it with a circular pressure plate to prevent water-gas short-circuiting during future operation.

3. After separating the interface between the head and the cylinder, weld and install them into the film former. Connect the other pipeline components according to the provided modification scheme diagram, and the job is complete. Once inspection is passed, the equipment can be put into operation.

4. During the modification process, the diameter of the deaerator head is generally not increased; instead, its height is appropriately adjusted based on the specific circumstances, usually only raised or installed and welded at the original height.