Renovation of deaerator head in rotary membrane deaerator

With the rapid development of power industry production and the continuous progress of science and technology, the spray pan type spray packing type and rotary film type deaerators put into operation in our early years are increasingly insufficient, which are mainly manifested in poor deoxidation rate, uneven heat exchange, low adaptation energy, large steam consumption, and cannot change with the change of working conditions and loads.

-The improved rotary membrane deaerator is a type of fully integrated deaerator that has been widely studied in recent years. The deaerator uses advanced stainless steel corrugated packing instead of the original woven Ω - shaped mesh fine wire stainless steel mesh and O-ring packing. The corrugated liquid vapor mesh has the characteristics of water flow impact without deformation, packing not falling off, high separation rate, small air resistance, and can perform secondary deaeration on feedwater.

The renovation design of the deaerator head of the rotary film deaerator mainly involves changing the original jet type to the rotary film type, which is a high-energy water film deaerator that combines rotary film and bubble boiling condensation. It has high deaeration rate, uniform heat exchange, low steam consumption, stable operation, adaptability to energy, and does not require strict water quality and temperature requirements, and can operate at full capacity.

Rotary membrane deaerator (Also known as membrane deaerator, it is a type of thermal deaerator that uses steam to heat the boiler feedwater to the saturation temperature at the corresponding deaerator working pressure, removing dissolved oxygen and other gases from the feedwater, preventing and reducing corrosion of the boiler feedwater pipe, economizer, and other auxiliary equipment. It can be used for constant pressure, sliding pressure, and other operation methods. The rotary membrane deaerator is suitable for deaeration of various types of power systems, boilers, industrial boiler feedwater, and thermal power plant feedwater.).

Applicable scope:

While supplying the complete set of - type rotary film deaerator, our company also undertakes the technical transformation work of the spray pan type and spray filler type rotary film deaerator in relevant power plants.

According to our company's previous technical transformation of deaerators in power plants, thermal power plants and self owned power plants in all regions, it is successful to transform the spray pan type, spray packing type and rotary film type deaerators into - type rotary jet film deaerators.

From the schematic diagram, it can be seen that the modification of the original deaerator is very convenient. That is to use the shell head part of the original deaerator head to remove all the water spray pan type or spray packing type and rotary membrane type components in the original head, keep the lower steam inlet plate, and then add a regular liquid steam screen and grate at the upper fixed position of the lower steam inlet plate, and then seal the annular pressure plate to prevent water vapor short circuit in future operation. Then, untie the interface between the head and the cylinder and weld it into the rotary jet film ejector, Connect other components of the pipeline according to the provided renovation plan diagram, and it is considered completed. After passing the acceptance inspection, it will be put into operation.

In the renovation process, the diameter of the deoxygenation head is generally not increased, and its height is appropriately changed according to the specific situation. Generally, it is only increased or welded according to the original height.

Function of rotary membrane deaerator -:

A rotary membrane deaerator is a type of thermal deaerator that utilizes the dissolution of gas in water. By heating steam, the supply water and condensate (including hydrophobic) entering the deaerator are heated to a saturation temperature relative to the internal pressure of the deaerator. According to Henry's law and Dalton's law, non condensable gases such as oxygen and carbon dioxide dissolved in water precipitate from the water, making the oxygen content of the water reach the specified standard.

The rotary membrane deaerator is fundamentally different from other types of thermal deaerator in terms of energy. The difference lies in the fact that the rotary membrane deaerator uses a membrane generator composed of a jet rotary membrane tube (referred to as the membrane generator) as a steam water heat exchange device. The water film formed by the membrane generator has a high heat storage coefficient, and it varies with water load or Reynolds Re, and is proportional to the temperature difference. The heat and mass exchange is sufficient, and the flow is, And the design of the membrane tube takes into account both liquid heat and mass transfer and vapor mass transfer, resulting in good deaeration performance of the membrane deaerator.

Rotary membrane deaerator junction---

The rotary membrane deaerator designed and manufactured by our company consists of two main components: a deaerator head and a water tank. The heating and deaeration of water supply are mainly completed at the deaerator head, and the water tank is used for water storage and buffering.

The deaeration head consists of two deaeration components:

--The deoxygenation component is composed of a cylinder, a partition, a rotating film tube, a flow tube, and a tube assembly welded into a body, which is divided into a water chamber, a steam chamber, and a water film skirt chamber.

The second deoxygenation component consists of two parts: the castor group and the filler.

The deaeration water tank is equipped with a distribution pipe, a reboiler pipe, an anti rotation plate, and various pipe sockets. Install on-site instruments, level gauges, and safety valves on the deaerator to meet the needs of on-site debugging and operation.

Rotary membrane deaerator with horizontal water storage tank, supported by double saddle. The deaeration head is connected to the water tank in a reverse skirt arc shape.

The deaerator provided by our company has the following features--

Deoxygenation - fruit-

In a relatively short period of time, the deoxygenated water dissolved oxygen content can meet the requirements of my 银行卡Water and Steam Standards for Thermal Power Plants银行卡.

Adaptation - Strong

Suitable for operation under conditions such as high dissolved oxygen content in inlet water, low inlet water temperature, and large pressure changes.

Stable--

When the load changes; Instantaneous replenishment water volume - variable time; When using different parameters of steam; When the inlet water temperature drops; The deoxygenated water quality can still maintain the qualified standard, and the deaerator will not vibrate, and the water inlet is not prone to vaporization and other situations.

Energy saving - fruit-

The exhaust steam volume of the membrane deaerator is less than 1 ‰ of the inlet water volume, which is 1/2 to 1/3 less than other types of thermal deaerator with the same output. There is no need to add an additional sewage cooler, which simplifies the equipment and reduces heat consumption.

Deaerator renovation:

While supplying the complete set of - type water film deaerator, our factory also undertook the transformation of the spray pan type and spray filler type deaerator in relevant power plants. The transformation into - type water film deaerator was successful, and the result was -. Specifically manifested in:

The renovation cost is low, about half of the cost of replacing the deaerator head. Progress: Easy to process and install on-site modifications. Deaerator with output below 220T/H can be completed within a week. Deaerator with output above 220T/H can be completed within half a month.

From the graph, it can be seen that the modification of the original deaerator is very convenient. That is to use the shell head part of the original deaerator head to remove all the water spray tray or spray packing parts in the original deaerator head, keep the lower steam inlet plate, and then install a liquid steam network and a water grate at the location above the lower steam inlet plate, and then seal and fix the annular pressure plate to prevent water vapor short circuit in future operation.

After loosening the interface between the head and the cylinder, weld and install it into the membrane separator. Connect other components of the pipeline according to the provided renovation plan, which is considered completion. After passing the acceptance inspection, it will be put into operation.

During the renovation process, the height should be appropriately adjusted according to the specific situation. Generally, the diameter of the deoxygenation head is not increased, but only increased or welded according to the original height.

Principle of rotary membrane deaerator:

-The heat and mass transfer methods of the improved rotary film deaerator are different from the existing drip tray, rotary film, and atomization methods. The main method is to reduce the three heat transfer methods of jet, rotary film, and hanging foam to a single body heat and mass transfer method, which has a high efficiency- The type rotary jet membrane tube has great analytical ability and causes the liquid film to rotate and suck a large amount of steam without the tube wall, enhancing heat and mass transfer functions. The opposed bubble boiling is changed to a suspended bubble boiling, which improves the flooding (splashing) of steam at high flow rates in each layer and can maintain the vapor (gas) channel; Shrink the three types of heat and mass transfer devices into a single unit and complete them within its components. Due to its high efficiency and certain unique functions, it has surpassed the technological capabilities of existing deaerators.

Application and model of rotary membrane deaerator:

CY -, CYG - series - type rotary jet membrane deaerator (hereinafter referred to as deaerator) is a type of deaerator that uses a steam turbine to extract steam to heat the boiler feedwater to the saturation temperature at the corresponding deaerator working pressure; Remove oxygen and other gases dissolved in the feedwater to prevent and reduce corrosion of boiler pipelines, economizers, and other ancillary equipment.

Its model consists of two parts: Chinese Pinyin and the main data (processing water volume T/H) of the deaerator.

For example, CYG-225T/H represents a high-pressure rotary jet membrane deaerator with a processing water volume of 225T/H.

Rotary membrane deaerator structure -

The structure of the deaerator mainly consists of an outer shell, a steam water separator, a rotary jet membrane separator, a water spray grate, a regular liquid vapor network, and a water tank.

1. Shell: It is made by welding the cylinder body and stamped elliptical head.

2. Soda water separator: This device replaces the original design of the straw cap cone structure inside the deaerator, eliminating the phenomenon of steam carrying water in the deaerator.

3. - Type rotary jet membrane generator: composed of water chamber, steam chamber, membrane generator, condensate connection pipe, supplementary water pipe, drainage connection pipe, and primary steam inlet connection pipe- A water film guiding device has been added to the rotary film tube of the type of rotary film ejector, which can effectively lower the film even during low load operation, maintaining a stable rotary film skirt.

Condensed water, chemical make-up water, is sprayed out in a spiral shape at a fixed angle through a membrane tube, forming a water film skirt. It is then heated to a saturation temperature close to the working pressure of the deaerator (i.e. - saturation temperature 2-3 ℃) in contact with the heating steam introduced by the secondary heating steam pipe and the secondary heating steam rising from the water tank through the liquid vapor network, and subjected to coarse deaeration- After this process, the membrane can remove about 90-95% of the oxygen content in the feedwater.

4. Water shower grate: It is composed of several layers of angled steel components arranged in a staggered manner. It is subjected to secondary distribution through membrane initiation, coarse deoxygenation of water supply, and high pressure heater drainage here. It evenly drips and falls onto the liquid vapor network installed below it.

5. Regular packing liquid vapor network: It is a cylindrical body composed of SW type mesh corrugated packing units with the same opening size. The regular packing maintains the outer surface of the wire mesh corrugated packing and the orifice plate corrugated packing, and has a large specific surface area, small pressure drop, large operating elasticity, high separation rate, low energy consumption, and never falls off. The feedwater is in full contact with the secondary steam here, heated to saturation temperature and subjected to degree deaeration. The low-pressure atmospheric deaerator is ≤ 10PPb, and the high-pressure deaerator is ≤ 5PPb.

6. Water tank: The deoxygenated water is collected into the water supply tank of the lower container of the deoxygenation head. The deoxygenation water tank is equipped with a scientifically designed strong heat exchange and reboiling device, which has strong heat exchange, quickly increases water temperature, deoxygenation, reduces water tank vibration, reduces noise, etc., improves the use of equipment, and ensures the safety and reliability of equipment operation.

Installation, operation, and maintenance of rotary membrane deaerator:

1. The installation of deaerator, water tank and accessories should be carried out according to the MCY-MCYG deaerator system diagram and this manual.

2. After welding the deaerator and water tank, a water pressure test should be conducted, and the pressure parameters of the water pressure test should comply with relevant regulations.

3. When officially put into operation, the safety valve should be adjusted. When the pressure inside the equipment reaches the specified value, the safety valve will automatically open.

4. Adjust the pressure automatic regulator to maintain the deaerator pressure within the specified range and the water tank outlet temperature within the specified temperature range. If the pressure of the deaerator exceeds the above range during operation, check if the automatic pressure regulator has malfunctioned. The butterfly valve has a positive water level of ± 200mm, which is the limit water level. The high water level discharge valve (electric gate valve) should be opened to discharge water, and it should automatically close when the water level drops. During operation, it is necessary to check whether the electric water level control system is flexible and whether the action of the supply water control valve is flexible.

5. During operation, the feed water should be heated to a saturation temperature close to the operating pressure of the deaerator (i.e. - saturation temperature 2-3 ℃) during membrane formation.

6. Adjust the opening of the exhaust valve to achieve an exhaust volume of approximately 2-3kg per ton of deoxygenated water.

7. The water level gauge of the water tank should be regularly flushed to prevent contamination.

8. When the deaerator is running, the inlet valve should be opened, followed by the heating steam valve. When stopping, the opposite is true. The inlet valve should be closed, followed by the inlet valve.

9. When checking the deaerator, the water in the water tank should be drained and cleaned.

10. When the deaerator is shut down for a long time, appropriate anti-corrosion measures should be taken.

Case study of improved rotary membrane deaerator and deaerator tower renovation:

Deaerator is one of the essential equipment in thermal power plants. It ensures the quality of boiler feedwater, especially the dissolved oxygen content that meets the requirements of equipment operation; However, due to various reasons, many deaerators fail to meet the required standards, resulting in corrosion damage to the system and seriously affecting equipment and safe operation. Therefore, it is urgent to renovate these deaerators. The proposed internal renovation plan for the deaerator can effectively address the issue of dissolved oxygen in the feedwater and bring gratifying economic benefits to the power plant.

-Units with a capacity of 100 MW and above are equipped with spray packing deaerator. These deaerators, especially those for 100 MW and 200 MW units, have been in operation for a considerable number of years. The spring nozzles have malfunctioned and the internal components have rusted and damaged; In addition, the deaerator packing produced after the 1970s uses Ω type packing, which is not as good as the target type stainless steel wire mesh material in terms of heat and mass transfer, energy diffusion, and energy. Therefore, the deaeration efficiency of many deaerators has decreased significantly, and some have strict standards. Especially when the demand for grid load decreases and the number of units frequently operate under partial or low load conditions, the dissolved oxygen standard is particularly strict. Therefore, in response to the urgent requirements for the renovation of deaerator in these power plants, it is recommended to adopt an internal renovation plan for deaerator, that is, only the key components inside the deaerator will be chemically modified when the deaerator shell and water tank shell meet the design strength requirements- The investment in the internal renovation plan is only 10% to 20% of the equipment cost, and the deoxygenation results can fully meet the operational requirements. Moreover, due to the use of chemical measures in components such as the steam inlet device and packing, its deoxygenation results, load adaptation, thermal economy, and other indicators are attractive. The successful renovation of the deaerator of the 200 MW unit in Shaoguan Power Plant has provided an economical, simple, and effective way for the renovation of similar equipment.

Overview of improved rotary membrane deaerator and deaerator tower renovation equipment

Unit 9 of Shaoguan Power Plant is a 200 MW unit produced by Harbin Steam Turbine Works, equipped with GWC-670 high-pressure spray packing deaerator produced by Harbin Boiler Works; The designed output is 670 t/h, with a maximum output of 700 t/h and a rated operating pressure/temperature of 0.49 MPa/158 ℃. After years of operation, the main problems with the renovation of the deaerator are: (1) the oxygen content in the feedwater is strict and unstable, such as 1.8-128.6 in November 1995 μ G/L, 0.2-15.3 in September 1996 μ G/L; (2) The Ω type packing is lost, and during operation, the Ω type packing falls off and enters the inlet of the feedwater pump, affecting safe operation; (3) The atomization nozzle spring is lost and detached, losing its adjustment function. Therefore, Shaoguan Power Plant has decided to renovate the deaerator of Unit 9. After a technical and economic analysis of the renovation plan, the Thermal Power Research Institute proposed a partial renovation plan for the deoxygenation head.

In July 1997, during the overhaul of the unit, the deaerator of Unit 9 was renovated. Since the deaerator was put into operation in August 1997, the equipment has been operating well. In order to assess and evaluate the thermal energy of the renovated deaerator, personnel from Shaoguan Power Plant and Thermal Research Institute jointly organized an energy test in March 1998- The design of the deaerator renovation is reasonable and effective, meeting the design requirements and meeting the requirements of the power plant for water quality, ensuring the safe and stable operation of the unit.

Design of 2 improved rotary membrane deaerator and deaerator tower renovation

Design of improved rotary membrane deaerator and deaeration tower renovation structure

The shell and external connecting pipes of the deaerator remain unchanged, and only partial modifications are made to the interior of the deaerator. (1) Adjust, repair or replace the spray spring nozzle with a new type spring nozzle;

Improved rotary membrane deaerator and retrofitted deaerator tower - energy test

Unit load variation test

The deaerator is a fixed sliding pressure operated deaerator. When the unit load changes, the operating conditions of the deaerator also vary with the different extraction parameters of Group 4, and the corresponding deaeration results of the deaerator are also different. To evaluate the deoxygenation results of the deaerator under different loads, especially at low loads, the test outline requires that the test should be conducted under 200, 180, 150, and 120 MW operating conditions. However, due to grid load reasons, the test should be completed at 135, 150, 160, and 170 MW loads respectively (see Table 2).

Table 2 Results of Variable Load Test for Improved Rotary Membrane Deaerator and Deaeration Tower Renovation

Exhaust valve opening test

Low pressure feedwater is heated and sprayed in the deaerator, and its non condensable gas, especially oxygen, continuously precipitates and accumulates in the deaerator- These gases must be discharged through exhaust devices to achieve the purpose of deoxygenation. However, the exhaust device will also discharge some steam while discharging non condensable gases, which will increase the heat loss of the unit. So, the purpose of the experiment is to determine the appropriate opening of the exhaust valve in order to fully discharge non condensable gases and reduce the amount of steam discharged. The test exhaust valves have two main openings × 1 lap, 2 × 1/2 turn, 2 × 1/4 turn (GWC670 deaerator is designed with two exhaust valves of the same specification arranged symmetrically), and the test results are shown in Table 3.

Table 3 Exhaust valve opening test for improved rotary membrane deaerator and deaerator tower renovation

Conclusion on the improvement of rotary membrane deaerator and deaeration tower renovation

Since the start-up and operation of the deaerator of Unit 9 after renovation, it has been proven through performance tests and long-term operational tests that the deaerator meets the requirements of the renovation design and can operate safely and stably while meeting the requirements of different water supply conditions.

5.1 The deoxygenation effect of the renovated deaerator is good, and the oxygen content in the effluent of the deaerator can reach 2-3% under rated operating conditions μ G/L.

5.2 The load adaptation of the deaerator is - able to operate at 60% to - rated conditions, and the oxygen content in the effluent of the deaerator is less than 7% μ G/L.

5.3 The design of the deaerator renovation adopts a degree of deaeration method that combines gas-liquid mesh packing and water grate. Its heat and mass transfer are good, especially the ability to precipitate non condensable gases is enhanced. Therefore, the exhaust valve opening after the deaerator renovation is only half of the renovation, reducing exhaust loss and improving system thermal economy.

5.4 Adopting a type of packing device avoids the impact of Ω packing loss on the operation of the boiler feedwater pump, and improves the safety of power plant operation.

5.5 Economic benefits. The internal renovation cost of the deaerator is only 10% to 20% of the equipment, saving about 200000 to 1 million yuan in funds; The renovated deaerator saves over 700 tons of standard coal annually, equivalent to approximately 150000 yuan, due to a decrease in exhaust volume; In addition, the improvement of water quality has extended the use of power generation equipment, and its economic benefits are particularly prominent.

-Special specifications can be arranged separately according to user needs for design schemes! Interested parties contact us!

Notice on Ordering for Improved Rotary Membrane Deaerator and Deaerator Tower Renovation

1. Order a complete set of - type rotary membrane deaerator and provide the following parameters:

Output of deaerator

The height, cylinder diameter, and wall thickness of the deaerator

The working pressure and temperature of each feedwater of the deaerator

2. The following data is required for the technical transformation of the - type deoxygenation equipment:

The height, cylinder diameter, and wall thickness of the existing deaerator

The working pressure and temperature of each feedwater of the existing deaerator

The output of the existing deaerator

Improved rotary membrane deaerator and deaerator tower retrofit model:

The CY series rotary jet membrane deaerator model consists of two parts: Chinese spelling letters and the main data (processing water volume T/H) of the deaerator. For example, CY-225T/H represents a high-pressure rotary membrane deaerator with a processing water volume of 225T/H.

CYG-系列-型压力式除氧器