I. Product Uses and Advantages

Deaerators are one of the key equipment in boilers and heating systems. The severe losses caused by oxygen corrosion to boiler feed water pipes, economizers, and other auxiliary equipment each year have drawn increasing attention from the National Electric Power Department. The Department has issued the GB1576-2001 "Water Quality Standards for Industrial Boilers" and the "Technical Supervision Regulations for Safety of Pressure-Reducing Deaerators in Power Stations," which establish departmental standards for oxygen content in deaerators. Specifically, 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 spiral membrane oxygen removal unit differs from the existing spray and spray plate types in its heat transfer, mass transfer methods, and oxygen removal capabilities. It is a new type of thermal oxygen removal unit that has won the Power Ministry's New Technology and New Product Science and Technology Innovation Award and has been listed as a key promotion product by the Power Ministry. The spiral membrane oxygen removal unit has been proven to have the following advantages after use:

High deoxygenation capability, with a 100% qualified oxygen content in the water after deoxygenation.

2: Stable operation with no vibration. Suitable for vacuum start and sliding pressure operation, reducing the need for complex manual adjustments during startup and operation.

3: High adaptability, not stringent requirements for water quality and temperature; can operate at 150% capacity for short periods.

4: Steam volume less than 0.1% of the inlet water volume; no additional exhaust cooler required. Optimized equipment, reduced heat consumption, and consumes 1/3 less energy than other types of the same output 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 membrane oxygen scavenger consists of an oxygen scavenging head and a water tank. The oxygen scavenging head is composed of the outer shell, rotating film assembly, water grating, liquid-vapor mesh, steam distribution plate, and steam-water separator into six main parts. The water tank is made up of the main body and accessories.

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

2. Membrane Assembly: Comprising a water chamber, membrane tube, condensate outlet pipe, and make-up water inlet pipe. Both the membrane 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 membrane deaerator, from which 98% of the oxygen is removed.

3. Water Distributor Grating: The water for deoxygenation after the membrane formation section and the condensate introduced from the drain pipes are reduced in flow and redistributed here, causing the water to fall evenly in a sprinkling 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 year-round without the need for maintenance.

4. Filling Liquid-Vapor Grid: Composed of spaced flat steel bands and a cylindrical shell, internally fitted with two layers of specially designed 0.3mm stainless steel flat O-shaped wire mesh. Here, water is in full contact with the secondary steam, heated to saturation temperature and deeply deoxygenated to ensure the oxygen content of the deoxygenated water.

5. Steam Distribution Plate: The main heating steam is introduced here, the uniform distribution structure ensures excellent heating quality, maintaining an even distribution of heating steam. It rises to heat softened water without throttling, working at saturation temperature to achieve deaeration.

6. Air/Water Separator: Composed of stainless steel filling for the internal network, the shell is designed with a ventilation structure, which effectively separates and recirculates water from the air during exhaust, an indispensable component for ensuring exhaust without water.

7. Water Tank: Welded from a cylindrical body and stamped elliptical heads, internally equipped with reinforcing rings. The base is mounted on a prefabricated worktable, with one end fixed and the other for installing an expansion roller assembly. The tank is fitted with a manway, safety valve connection, drain outlet, reboiler pipe connection, water seal cylinder port, level gauge interface, pressure gauge port, temperature gauge port, and water intake.

The basic principle of deaerator thermal deaeration: In the 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. This causes the partial pressure of steam above the water surface to gradually increase, while the partial pressure of dissolved gases decreases, causing the dissolved gases to continuously escape. When the water is heated to the boiling temperature at the corresponding pressure, the surface is entirely steam, and the partial pressure of dissolved gases is zero, meaning water no longer has the ability to dissolve gases, including oxygen, which can then 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 exclusion, which is greatly related to the size of the water and steam contact surface area.

Principle of the Rotating Disc Oxygen Remover (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 unit within the deaerator, and under a certain pressure difference, they are obliquely sprayed into the inner cavity through small holes in the membrane tubes, forming a jet. Due to the inner cavity being filled with rising heated steam, the water absorbs a large amount of heated steam during its jet motion (experiments prove that the jet motion has an entrainment effect); this results in a violent mixing and heating effect over a very short distance, significantly increasing the water temperature. As the rotating water continues to spiral down along the inner wall of the membrane tube, it forms a swirling water film skirt. (The critical Reynolds number of the water decreases significantly during rotation, leading to turbulent swirling.) 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 diffuse freely within the inner cavity and must rise with the steam, exiting through the exhaust pipe into the atmosphere. The feed water from the rough deaeration section and the condensate introduced from the drain pipes are mixed here for secondary distribution, falling in a uniform rain-like pattern onto the liquid-vapor net below. After deep deaeration, the water flows into the water tank. The oxygen content in the water within the tank is 0-7 μg/L at high pressure and less than 15 μg/L at low pressure, meeting the departmental operational standards.

Due to the oxygenator's continuous turbulence in water and its ample heat exchange surface area, the better the heat transfer and mass transfer efficiency, the smaller the exhaust steam volume (meaning less steam used for heating, leading to lower energy loss and significant economic benefits). The excellent deoxygenation effect allows the oxygenator to operate beyond its capacity (usually up to 50% over the rated output) or meet operating standards under low water temperature full replenishment.

4. Installation, Operation, and Maintenance

1. Installation, operation, and maintenance of deaerators, water tanks, and accessories should be carried out according to the CYD(G) type deaerator system diagram and <<Technical Supervision Regulations for the Safety of Power Plant Deaerators>>.

2. The deaerator should be placed above the feed pump, and the difference in elevation between the lowest water level of the deaerator tank and the centerline of the feed pump should be no 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, a water level transmitter on the deaerator, to monitor signals such as incoming water temperature, flow rate, and deaerator water level. These signals are then input to the calculation and processing module to control the hydraulic and thermal balance of the deaerator's water inlet and heating steam. This ensures the deaeration effect is achieved, maintaining the deaeration temperature at (104±1.5℃). Adjust the electric actuator regulating valve installed on the steam pipe to control the steam flow, which automatically adjusts the steam flow rate based on the temperature of the deaerated water. After topping up is complete, the electric actuator automatically closes.

4. The lower part 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 start-up. For the first use, gradually open the reboiling heating tube valve at the bottom of the water tank when the water level exceeds half, to heat the water inside the tank and maintain it in a boiling state. The reboiling tube should be turned off immediately after the unit is started and loaded. Additionally, a prevent-rotation plate is installed at the outlet tank opening to prevent water from swirling at low water levels, thereby increasing the effective volume of the water tank. Tests have shown that water swirling has a significant impact on pump cavitation. Without a prevent-rotation plate, the water level in the tank must be maintained at three times the pipe diameter. With a prevent-rotation plate, it can be reduced to below 1.5 times.

5. After on-site welding of the deaerator and water tank, a hydrostatic test should be conducted. The pressure parameters for the hydrostatic test are: atmospheric deaerator, 0.2 Mpa; pressure deaerator, 0.75 Mpa. Accumulate the condensate steam in the intermediate storage tank as much as possible before sending it to the deaerator. Then, evenly distribute these condensates into the deaerator to ensure stable deaerator load.

6. Oxygen Scavenger with Protective and Alarm Systems

(1) The water tank and deaerator are equipped with an adequate number of full-blow safety valves, which should meet the design technical specifications.

(2) The oxygen-removing membrane should be equipped with both local and remote water level gauges, along with high and low water level alarms and action devices for dangerous high and low water levels. The water level change control of the oxygen-removing unit: when the water level drops, the softening water pump (condensate pump) automatically starts to replenish the oxygen-removing unit; when the water level rises, the pump automatically stops.

7. Preheat the deaerator shell for 10-15 minutes using auxiliary steam before starting up in cold condition. Under a certain steam pressure, introduce demineralized water into the deaerator head while adjusting and increasing the steam inlet valve to heat the feedwater in the film-forming section to near the steam saturation temperature for deaerator operation (i.e., 102-104°C).

8. Adjust the water level regulation 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 within the deaerators, each deaerator tank must have a connecting pipe for steam and water to equalize. Aim to make 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 open and drain water freely. It should automatically close when the water level decreases. During operation, regularly check the responsiveness of the electromagnetic water level regulation system and the suppleness of the feed water regulating valve.

9. Gently open the top exhaust valve, open the valves on the steam pipe, supply steam for heating, and record the steam pressure and temperature. Adjust the exhaust valve opening to about 2/3, allowing the exhaust flow to be around 2-3kg per ton of deaerated water.

10. When operating the deaerator, the inlet valve should be opened first, followed by the heating steam inlet valve; when shutting down, do the opposite.

12. During the operation of the deaerator, if water in the exhaust steam is detected, the following methods can be adopted for handling:

Adjust the heating steam inlet valve

b. Inspect pressure adjustment device

c. Manual降压operation

d. Gradually close the secondary heating steam cutoff valve.

13. Test the oxygen content of the water in the sampling tank to ensure it meets the standard. If it does not, adjust the water inflow, air inflow, and exhaust gas flow to achieve compliance. Once qualified, you can supply water to the boiler.

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

15. Cautionary Notes

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

b. During operation, attention should be paid to ensure that the pressure within the deaerator does not drop sharply, and a vacuum should not be formed.

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

d. The deaerator should be inspected regularly to prevent nozzle clogging, packing corrosion or compaction, and instrument failure.

e. If the deaerator has been 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, it automatically opens to relieve pressure when the internal pressure of the equipment exceeds the allowable limit, serving as a safety protection function.

Pressure Gauge — Installed at the top of the deaerator, monitoring the pressure within the equipment.

·Thermometer — Located below the water tank, monitoring the water temperature inside the tank.

· Butterfly valve - Installed on the heating steam pipeline, utilizes an automatic regulator to adjust the flow of heating steam, maintaining the pressure within the oxygen-removing vessel at the rated level.

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

· Stop valve—Installed on the refilling 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 --- Installed on the topping-up pipe, it regulates the flow rate of topping-up water using an electric water level control system to maintain the normal water level of the tank.

·Electrical contact level monitoring—Composed 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 and outputs a 4-20mA signal to the control room to regulate the water level valve.

· Magnetic Flip Level Gauge --- Installed on the water tank, it monitors the water level in situ and can also be connected remotely to output a 4-20mA signal to the control room for adjusting the water level valve.

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

·Electric gate valve - Installed on the drain pipe of the water tank, it automatically opens when the water level in the tank exceeds a certain limit, utilizing the electric water level regulating system to discharge the excess water to the overflow tank.

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

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

Section 6: Order Provision Data

1: Oxygen separator output (T/H) and effective tank volume (m³).

2: Oxygen Remover Operating Pressure, Temperature...

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

Section 7: Renovation

Our factory offers a complete supply of new-type water film deaerators while also undertaking the retrofitting of deaerators with spray plate and spray packing designs for power plants. Specifically, this includes:

The retrofitting cost is about half the price of replacing the degasser head.

2. Fast progress, easy to process and on-site modification and installation. Utilize the shell head part of the original deaerator, remove all the spray plate or spray packing components inside, retain the lower steam inlet plate, then install the liquid-gas mesh and water grating at a certain position above the lower steam inlet plate. Finally, use the annular pressure plate for sealing and fixing to prevent water-gas short circuit during future operation.

3. Next, disconnect and weld the joint between the head and the cylinder to fit it into the film former. Connect the other components at the pipe opening according to the provided modification plan, and the job is complete. After passing the inspection, it can be put into operation.

4. During the modification process, it is generally not necessary to increase the diameter of the deaerator head. Instead, adjust its height appropriately based on specific circumstances, usually by either increasing or welding it at the original height.