I. Overview:

The new water film deaerator is installed in a horizontal tank and a vertical deaerator head, connected by welding. The new spiral film deaerator is the latest thermal deaerator developed and manufactured by our company (Patent No.: ZL 2010 2 0265898.2), which has won the first Innovation Award for New Technology, New Products, and Scientific and Technological Research Achievements from the Power Department and is listed as a key product for promotion and application. This product fundamentally differs from spray-filled and water film deaerators, especially after the second improvement in 2004. The product performance has become even more perfect, with a dissolved oxygen removal rate of 100%. When operating under design conditions, the high-pressure deaerator can control the dissolved oxygen level below 5 μg/L, and the low-pressure deaerator below 10 μg/L. The heat and mass transfer method of the new spiral film deaerator is different from the existing spray plate, atomization, and spiral film types, as it combines the heat and mass transfer methods of the three forms into one. It boasts high heat transfer efficiency and deaeration capacity.

Section II: Technical Status:

Currently, the three common types of oxygen removal systems on the market are the spray disk type, spray type, and spray packing type. The spray disk type has been gradually phased out due to its low oxygen removal efficiency and tendency to vibrate during operation. The spray type and spray packing type, with some advantages, are still used by some customers, but their drawbacks are also becoming apparent during operation. Particularly, both types of oxygen removal systems cannot operate beyond their capacity under special conditions, and the oxygen heads are prone to vibration at low water temperatures, which is increasingly drawing attention from the technical community.

The spray-type deaerator operates on a principle similar to that of the atomizing nozzle. The spray-filled deaerator sprays water through membrane holes, then downward along the tube mouth. It meets with heated steam rising from the deaerator head, forming a heat exchange zone. After a brief pause, the atomized water falls onto the Ω-shaped packing for further heating, finally descending into the lower water tank to complete the heat exchange process. Since the heat exchange in the spray-type deaerator primarily occurs at the 300mm lower end of the nozzle, the deaerated water in this section is in an atomized state, thus the deaeration efficiency in the upper section is nearly equivalent to that of the spray type. The Ω-shaped packing layer serves as the deep deaeration zone for the deaerated water. The dispersible and deformable characteristics of the "Ω" packing often lead to its detachment from the spray holes into the water tank or deformation into lumps, affecting water flow and significantly reducing the deaerator's output. These drawbacks of the spray-filled deaerator, although it can meet the national deaeration requirements initially, result in substandard deaerated water once issues arise with the packing layer, with some exceeding standards by three times or more, and the dissolved oxygen in the low-pressure deaerator effluent reaching 50μg/L. Moreover, frequent replacement of the packing is required, leading to extended downtime and high maintenance costs.

The disadvantages of the above three types of deaerators are as follows:

Due to the imbalance in the exchange process, it is prone to vibration during operation.

2. The dissolved oxygen is not up to standard when there is a change in load, and it cannot be adjusted with the load.

3. High failure rate, short maintenance cycle, and high maintenance costs.

4. High exhaust gas volume, high consumption of new steam, and not energy-saving.

5. Nozzle prone to detachment.

6. The packing is prone to falling off, or it deforms and compacts into a block, resulting in a small exchange area, which affects output.

III. Technical Features of the New Water Film Oxygen Remover

The new generation spiral membrane oxygen removal unit is an upgraded product of the spray and water film types, combining the advantages of various oxygen removal units and undergoing a deep optimization design.

Low steam flow, meets energy-saving requirements (steam flow data of various deaerators: tray-type 5%, spray packing 3%, rotating film 1%). Energy-saving economy is quite remarkable.

(1) Technical Performance:

The research and pursuit indicators for thermal deaerators across various countries are primarily the spray density (also known as heavy flow rate), as well as the temperature rise and the concentration difference of dissolved oxygen. The efficiency of the water film deaerator is significantly higher than that of other deaerator models. The efficiency of various deaerators is summarized in Table 1-1:

Table 1-1 Efficiency Ratios of Various Oxygen Removers

(II) Utilizes an advanced five-stage deoxygenation principle, as follows:

1. Primary Deoxygenation

The high-efficiency defoamer is an improvement on the original rotating membrane deaerator, replacing the simple rotating membrane tube with a water preheater. The upper section is the water chamber, and the lower section is the steam chamber. The water in the water chamber is injected into the tube wall through tangential membrane holes, where it intersects with the steam flow reversing and exchanging heat as it rapidly spirals down the tube wall. This heat exchange section is the first stage of the new water film deaerator, also known as the preheating section, where 80% of the heat exchange takes place.

2. Secondary Deoxygenation

Deoxygenated water, after being preheated through the tube wall and spun down to the membrane tube outlet, is specially designed to continue membrane skirt atomization and ejection, where it mixes with secondary heated steam. This section is the second heating stage, and it is the deoxygenated water saturation section. In this section, the water is nearly or has reached saturation, with oxygen and other gases dissolved in the water overflowing from the boiling water. The oxygen content in this section typically approaches about 15 μg/L.

3. Triple Deoxygenation

The demister is designed with an additional water distribution grating at the lower section, which redistributes the water and facilitates a thorough steam-water mixing exchange. This ensures even water flow distribution, reducing the surface tension of the water film for further oxygen removal.

4.四级脱氧

The deaerators of this type are all filled with high-efficiency, regular woven wire mesh, which not only boasts an extremely high heat transfer efficiency but also features a long service life, resistance to high temperatures without deformation or shedding, and is made of stainless steel. The water undergoes deep deaeration in this section, and when it falls into the water tank, the oxygen content has reached 10 μg/L.

5. Five-level Deoxygenation

The bottom reboiling unit of the new water film deaerator not only serves as a tank preheating device during the unit start-up, but also, due to its rational design, can achieve even heating. It can be continuously operated without vibration for normal operation, providing auxiliary deaeration effects.

The five-stage deoxygenation principle of the new water film deoxygenator ensures the deoxygenation efficiency during normal operation of the equipment. Its features are as follows:

Dissolved oxygen levels can reach below 10 μg/L, significantly lower than the national standard of 15 μg/L.

2. The excess deoxygenation space allows the deoxygenator to operate significantly beyond its rated capacity (usually exceeding 50% of the rated output).

3. Due to its extremely high heat exchange efficiency, it can operate with low-temperature incoming water (full makeup water).