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 feedwater pipes, economizers, and other auxiliary equipment annually 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 "Safety Supervision Regulations for Pressure-type Deaerators in Power Stations," which set departmental standards for the oxygen content of deaerators, namely, the oxygen content in the feedwater of low-pressure deaerators should be less than 15 μg/L, and the oxygen content in the feedwater of high-pressure deaerators should be 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 tray deoxygenators. It is a new type of thermal deoxygenator that has won the Power Ministry's New Technology and New Product Science and Technology Innovation Award 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 capability; 100% pass rate for the oxygen content in the water after deoxygenation.

2: Stable operation 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 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 one-third less energy than other types of heat exchangers with the same output.

II. Technical Specifications and Matching Parameters

CYG Series New Type Pressure Oxygen Remover

Section 3: Structure and Principle (Illustration Included)

The structure of the spiral membrane oxygen remover consists of the deoxygenation head and the water tank. The deoxygenation head is composed of six main parts: the outer shell, the spiral membrane assembly, the water grate, the liquid-gas screen, the steam distribution plate, and the steam-water separator. 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: Composed of the water chamber, membrane tube, condensate water inlet, and make-up water inlet. 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. Drip Grating: The water supplied after oxygen removal in the film formation section and the condensate introduced through the drain pipes are reduced in flow and redistributed here, causing the water to fall in a uniform drizzle, thereby protecting the lower liquid-vapor grid. The space area of the water grate 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 Network: Consists of alternating flat steel strips and a cylindrical body, internally equipped with two layers of specially designed 0.3mm thick O-shaped stainless steel flat wire mesh. Here, water is fully contacted with secondary steam, heated to saturation temperature, and undergoes deep deoxygenation to ensure the oxygen content in the deoxygenated water.

5. Steam Distribution Plate: The main heating steam is connected here, the regular distribution structure ensures excellent heating quality, allowing the heating steam to be evenly distributed. It rises to heat softened water under no throttling condition, operating at saturation temperature for deaeration.

6. Air-Water Separator: Composed of stainless steel packing, the internal network is designed with a ventilation structure. It effectively separates and recirculates water from the steam during exhaust, and is an indispensable component to ensure exhaust without water.

7. Water Tank: Welded from a cylindrical body and stamped elliptical end caps, internally fitted with reinforcing rings. The base is mounted on a prefabricated workbench, with one end fixed and the other for installing the expansion roller assembly. The tank is equipped with manholes for maintenance, safety valve connection ports, drain outlets, reboiler pipe openings, water seal cylinder openings, level gauge interfaces, pressure gauge ports, temperature gauge ports, and water intake ports.

The basic principle of thermal deaeration in a deaerator: 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 gradually increases the partial pressure of steam above the water surface while decreasing the partial pressure of dissolved gases. Consequently, dissolved gases continuously escape. When the water is heated to its boiling point at the corresponding pressure, the surface is entirely steam, and the partial pressure of dissolved gases is zero, meaning water can no longer dissolve gases, including oxygen. The effectiveness of deaeration depends on whether the feedwater is heated to the boiling point at the corresponding pressure and on the rate of gas removal, which is greatly related to the contact area between water and steam.

Principle of operation for the rotating film oxygen removal unit (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 separator in the deaerator, where, under a certain differential pressure, they are斜旋喷向 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 in the jet draws in a large amount of heated steam (tests have proven the jet's entrainment effect); this results in a violent mixing and heating process over a very short distance, significantly raising the water temperature. As the rotating water continues to spiral down along the inner wall of the membrane tubes, it forms a swirling water film skirt (the critical Reynolds number of the water in the rotating flow decreases significantly, causing turbulent swirling). At this point, the turbulent state of the water offers the most ideal heat transfer and mass transfer efficiency, reaching the saturation temperature. Oxygen is then separated out, as it cannot diffuse freely within the inner cavity and must follow the rising steam out through the exhaust pipe to the atmosphere. The water from the rough deaeration section of the feed water and the condensate introduced from the drain pipes are mixed here for a second distribution, falling evenly like rain onto the liquid-vapor grid below, and are then deeply deaerated before flowing into the water tank. The oxygen content in the water within the tank is at high pressure 0-7 mg/L and at low pressure less than 15 mg/L, meeting the departmental operating standards.

Due to the oxygenator's use of turbulent flow, maintaining water in a constant state of turbulence, and its ample heat exchange surface area, the better the heat transfer and mass transfer effects are. This results in a smaller exhaust gas volume (i.e., less steam used for heating, leading to reduced energy loss and significant economic benefits). The excess oxygen removal efficiency allows the oxygenator to operate beyond its rated capacity (typically up to 50% of the rated output) or to meet operating 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 shall be conducted according to the CYD (G) type deaerator system diagram and the "Technical Supervision Regulations for the Safety of Power Plant Deaerators."

2. The deaerator should be placed above the feed pump, with the height difference 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 and processing module. This controls the hydraulic and thermal conditions of the deaerator's incoming water and heating steam to achieve the desired deaeration effect, ensuring the deaeration temperature is maintained at (104±1.5℃). Adjust the electric actuator regulating valve installed on the steam pipe to heat the incoming steam, automatically adjusting the steam flow rate based on the temperature of the deaerated water. After the water topping up is stopped, the electric actuator automatically closes.

4. The bottom of the water tank is equipped with a redial heating tube, which is used for heating and deoxygenation during boiler water filling and unit startup. For the first use, slowly open the bottom redial heating tube valve of the water tank when the water level exceeds half, to heat the water inside the tank and maintain it in a boiling state. Stop using it after the unit is started and loaded. Additionally, a anti-rotation plate is installed at the outlet tank mouth to prevent water swirl at low water levels, thereby increasing the effective volume of the tank. Tests have shown that water swirl has a significant impact on pump cavitation. Without an anti-rotation plate, the water level in the tank must be maintained at 3 times the pipe diameter, while with an anti-rotation 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: 0.2 Mpa for atmospheric deaerators and 0.75 Mpa for pressure deaerators. Before sending the steam condensate into the deaerator, it should be accumulated in the intermediate storage tank as much as possible. Then, evenly distribute this condensate into the deaerator to ensure stable deaerator load.

6. Protective Measures and Alarms for the Rotating Membrane Oxygen Scavenger

(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 Scavenger Membrane should be equipped with both local and remote water level gauges, and have high and low water level alarms as well as dangerous high and low water level actuation devices. The oxygen scavenger's water level change control operates by automatically starting the softening water pump (condensate pump) to replenish the oxygen scavenger when the water level drops; the pump automatically stops when the water level rises.

7. For the cold start-up of the deaerator, it is recommended to preheat the shell with auxiliary steam for 10-15 minutes. Under a certain steam pressure, introduce demineralized water into the deaerator head, while adjusting and increasing the steam inlet valve to heat the feed water in the film formation section to a temperature close to the steam saturation temperature of the deaerator's operating pressure (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 inside the deaerators, each deaerator tank must have a balanced pipe for steam and water connection. Aim for consistent pressure, water temperature, and water level as much as possible.) When the water level reaches ±200mm of the normal level, the high water level drain valve (electromagnetic gate valve) should be able to open freely to drain water, and it should automatically close when the water level decreases. During operation, it is necessary to frequently check the responsiveness of the electromagnetic water level regulation system and the responsiveness of the water supply adjustment valve.

9. Gently open the top exhaust valve, open the valves on the steam pipeline, provide steam heating, and record the steam pressure and temperature. Adjust the exhaust valve to about 2/3 open to achieve an exhaust flow of approximately 2-3kg per ton of deaerated water.

10. When the deaerator is operating, the inlet water valve should be opened first, followed by the steam inlet valve, and the opposite when shutting down.

12. During the operation of the deaerator, if a phenomenon of steam discharge with water is observed, the following methods can be adopted for handling:

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 it meets the standard. If it doesn't, adjust the water inflow, air inflow, and exhaust 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 from various monitoring instruments, to ensure the deaerator operates properly.

15. Cautionary Notes

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

b. During operation, attention should be paid to ensure that the pressure within the deaerator does not drop sharply, nor should a vacuum be formed.

c. In case of short-term shutdown, prevent the deaerator from forming a vacuum or becoming air-filled. 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 are required to prevent nozzle clogging, packing corrosion or compaction, and instrument malfunction.

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

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

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

· Butterfly Valve---Installed on the heating steam pipeline, adjusts the flow of heating steam with the help of an automatic regulator, to maintain the pressure in the deaerator within the rated range.

· 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 acts as a pressure relief 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 water replenishment pipe, it uses an electric water level regulation system to adjust the flow of water replenishment to maintain the normal water level in the water tank.

·Electrical Contact Level Monitoring --- Comprises a sampling electrode tube, an electrical contact level monitor tube (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 4-20 mA 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 Container — Used in conjunction with pressure/differential pressure transmitters and level gauges, it can reflect the deaerator's (weight) water level during boiler startup, shutdown, and normal operation.

·Electric gate valve — Installed on the water outlet pipeline of the water tank, when the water level in the tank exceeds a certain limit, the electric gate valve automatically opens with the help of the electric water level regulation system, and the excess water above the limit is drained into the overflow tank.

· Pressure Automatic Regulator---Automatically adjusts the opening of the steam inlet valve to regulate steam flow and maintain stable pressure within the deaerator.

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

Section 6: Order Provision Data

1: Oxygen removal capacity (T/H) and the effective volume of the water tank (m³).

2: Oxygen separator working pressure, temperature...

3: Only replace the oxygen scavenger tower, include the installation connection diagram of the original oxygen scavenger tower.

Section 7: Renovation

Our factory not only supplies complete sets of new water film deaerators but also undertakes the modification of deaerators for power plants, including those with sprinkling tray and spray packing designs. Specifically, we offer:

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

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

3. After separating the joint between the head and the cylinder, weld and install them into the film former. Connect the other components of the pipeline opening according to the provided modification plan. The job is then complete. Upon passing the inspection, the equipment can be put into operation.

4. During the renovation process, the diameter of the deoxygenation head is generally not increased. Its height is adjusted appropriately according to the specific circumstances, usually only raised or welded at the original height.