Pressure type double body deaerator
key word：Heat exchange element
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Product description
Pressure type double body deaerator
1. Introduction
1.1. Purpose
Pressure type double body deaerator is an important auxiliary equipment of steam turbine generator set. It is composed of two connected horizontal vessels. The upper vessel is a thermal deaerator (deaerator head) and the lower vessel is a water storage tank. The two vessels are connected by connecting pipes and supports.
1.2. Model meaning
YYW-**/##
YYW -------- code of pressure deaerator
** -------- rated output of deaerator (t/h)
## -------- the effective water storage volume of deaerator water tank is (m3)
1.3. Structural features
1.3.1. Structural form:
1.3.1.1. spray packing. The internal deaerator consists of constant velocity nozzle and stainless steel ring packing
1.3.1.2. spray spray tray. The internal deaeration components of the deaerator are mainly composed of constant speed spray valves and stainless steel deaeration discs.
1.3.2. Structure description. The condensation water enters the spring nozzle through the inlet device, because the pressure of the condensate is higher than that of the deaerator, and the pressure difference between the water and steam acts on the spray nozzle ring of the spring nozzle. The nozzle spring is compressed to open the nozzle, so that the condensate water is ejected, and a conical spray like water film enters into the spray deaeration space. Fully contact and quickly heat the condensate to or near the saturation temperature of the deaerator working pressure. Most of the oxygen and non condensable gases in the condensate are removed in the spray deoxygenation section. The condensate after preliminary deoxidization is evenly sprayed on the lower drenching pan and mixed with the drainage of high-pressure heater to form a layer of water cushion, which is redistributed through the sprinkling tray and dripped to the lower packing layer through the small hole for deep deaeration, so as to make the oxygen content of boiler feed water reach the standard value. Because the partial pressure of oxygen in steam is less than that of oxygen in water, oxygen and other non condensable gases continuously precipitate in the above heat transfer process. At the same time, the steam releases heat and condenses, and oxygen and other non condensable gases are discharged through the top exhaust device. The deoxidized water that reaches the standard value flows into the deaerator tank from the outlet pipe at the bottom of the deaerator head to meet the requirements of boiler water supply.
1.3.3. Description of important parts:
The main functions of the water inlet device are as follows: the water inlet device of the water heater is composed of the water inlet device and the water inlet device of the water heater (see Fig. 29-1). Among them, spring nozzle, drenching device and packing layer device are the main deoxidizing components.
The shell is welded by the cylinder body and two standard elliptical heads at both ends. Two saddle supports are installed at the bottom of Deaerator and matched with the two upper supports on the top of water tank. The bolts and nuts are connected between them to make the deaerator stack on the water tank smoothly.
The water inlet device is welded by a main pipe and a plurality of pipe joints. The condensate is distributed to each nozzle through the main feed pipe, and then evenly flows into each spring nozzle.
In order to avoid vibration and noise of deaerator, the high-pressure heater drain pipe is made into a porous nozzle structure at a specific position which extends into the inner side of the shell to disperse energy dissipation for the high-energy medium entering the deaerator.
The intake pipe is introduced from the ends of the deaerator, and a number of small holes are arranged inside and outside the baffle plate respectively, so that the heating steam can be divided into two ways according to a certain flow ratio, one way flows through the baffle hole, and the other passes through the packing layer, and finally flows into the atomizing space of the deaerator.
The rated flow rate of spring nozzle is 50 t/h and 100 t/h, which is made of all stainless steel. The spring nozzle and water inlet device are connected by flange, bolt and nut. The flow rate of the spring nozzle increases with the increase of the pressure difference, so that the condensate can be atomized well under all kinds of load conditions, so as to meet the needs of the variable working conditions of the deaerator, and can adapt to the variable load range of 10% - 110%. The spring nozzle can avoid the steam backflow into the condensate pipeline.
The sprinkling device is used to distribute condensate water sprayed by spring spray nozzle, and is made of stainless steel perforated plate and multiple rising exhaust pipes. During normal operation, a layer of water cushion is formed on the porous plate to overcome the resistance of the small hole and the steam pressure difference between the upper and lower parts of the orifice plate, and the condensate water can be evenly poured into the packing layer below it in the form of rain after distribution (for packing type).
The packing layer device is composed of upper and lower orifice plates, side plates on both sides and annular packing. The ring packing material is stainless steel with large specific surface area, which is stacked irregularly between two orifice plates. After evenly distributed by the sprinkling device, the condensed water flows through the packing layer to form a very thin water film. The packing layer extends the contact time of steam and water, constantly updates and analyzes the water surface, increases the contact surface area of steam and water, and ensures that the condensate can fully contact with the heating steam introduced from the lower part, and the dissolved oxygen can fully escape.
1.3.3.2. The deaeration water tank is used to realize the water storage function of the equipment. It is mainly composed of shell, support, recirculation nozzle of feed pump, reboiler nozzle, etc. (see Fig. 29-2).
The water tank shell is welded by the cylinder body and two standard elliptical heads at both ends. The upper part is equipped with two upper supports to match with the deaerator support, and the lower part is supported by saddle support, one of which is fixed support and the other is sliding support.
The recirculation nozzle of feed water pump is made into a porous nozzle structure at the specific part extending into the inner side of the water tank to disperse and dissipate the energy of the high-energy medium entering the water tank, so as to avoid the vibration and noise of the deaerator.
The reboiling connecting pipe is also called pre heating steam pipe. The material of connecting pipe is stainless steel. There are a certain number of small holes in specific parts. The steam is ejected through the small holes, and the water is heated evenly. This structure can avoid the vibration and noise of deaerator.
The effect of recirculation and reboiler nozzles of feed pump is the same as that of single simple deaerator.
2. Main technical parameters and product appearance
2.1. Main technical parameters (see table 29-1 and table 29-2)
Table 29-1 main technical parameters of dual deaerator
| Item | 300MW Unit | 600MW Unit | 1000MW Unit | |||
| Deaerator | water tank | Deaerator | water tank | Deaerator | water tank | |
| Rated output (t/h) | 1080 | 1995 | 3185 | |||
| Effective volume（m3) | — | 150 | — | 235 | — | 310 |
| Equipment and materials | 16MnR+0Cr18Ni10Ti | 16MnR | 16MnR+0Cr18Ni10Ti | 16MnR | 16MnR+0Cr18Ni10Ti | 16MnR |
| Internal diameter of equipment (mm) | 2800 | 3400 | 2800 | 3400 | 3000 | 3900 |
| Total equipment length (mm) | 7850 | 21300 | 17500 | 31500 | 12400 | 32800 |
| Wall thickness of cylinder (mm) | 18+3 | 25 | 20+3 | 25 | 22+3 | 28 |
| Equipment weight (t) | 24.5 | 57.5 | 38 | 95 | 50 | 130 |
| Corrosion allowance (mm) | 0 | 1.6 | 0 | 1.6 | 0 | 1.6 |
| Coefficient of welded joint | 1 | 1 | 1 | 1 | 1 | 1 |
| Effluent oxygen content (ppb) | ≤5 | ≤5 | ≤5 | |||
| Exhaust loss (‰) | 2～3 | 2～3 | 2～3 | |||
| Output of single nozzle（t/h） | 50 | 50 | 100 | |||
| Number of spring nozzles (piece) | 16 | 32 | 22 | |||
| Total height after assembly (m) | 8.03 | 8.03 | 8.9 | |||
Table 29-2 parameters of supporting accessories
| No. | Model & Name | Suit 300WM unit | Suit 600WM unit | Suit 1000WM unit | |||
| Specification | Quantity | Specification | Quantity | Specification | Quantity | ||
| 1 | A48Y-25 spring full lift safety valve | PN2.5, DN150 | 2 | PN2.5, DN150 | 3 | PN2.5, DN200 | 4 |
| 2 | Pressure gauge | Y-150 | 1 | Y-150 | 2 | Y-150 | 2 |
| 3 | Bimetal thermometer | WSS | 2 | WSS | 2 | WSS | 2 |
| 4 | Magnetic flap water level gauge (including primary valve) | L=3400mm | 2 | L=3400mm | 2 | L=3600mm | 2 |
| 5 | Tee valve (for pressure gauge) | J11-32; PN32, DN4 | 2 | J11-32; PN32, DN4 | 2 | J11-32; PN32, DN4 | 2 |
| 6 | Balance vessel (including primary door) | Single chamber | 3 | Single chamber | 3 | Single chamber | 3 |
| 7 | Electric exhaust valve (for starting exhaust) | PN2.5, DN80 | 1 | PN2.5, DN100 | 2 | PN2.5, DN100 | 2 |
| 8 | Exhaust orifice (for operation exhaust) | PN2.5, DN100 | 1 | PN2.5, DN100 | 1 | PN2.5, DN150 | 2 |
| 9 | Deaerator emergency water discharge electric valve | PN2.5, DN200 | 1 | PN2.5, DN250 | 1 | PN2.5, DN250 | 1 |
| 10 | High water level overflow electric valve | PN2.5, DN150 | 1 | PN2.5, DN200 | 1 | PN2.5, DN200 | 1 |
2.2. Product appearance (see figure 29-3)
3. Selection method
3.1. Performance parameters
The following data shall be included in the user's inquiry:
3.1.1. Special requirements for design parameters under design conditions.
Rated output
3.1.3. Effective water storage capacity of water tank
3.1.4. Special requirements for equipment and materials
3.1.5. Spacing and quantity of supports
3.1.6. structure, such as spray filler and spray water dish.
3.1.7. Design standards and relevant standards, plus ASME and national standards.
3.1.8. Requirements for painting, marking, packaging and transportation
3.1.9. Performance guarantee value
3.1.10. Heat balance diagram of steam turbine under various operating conditions
3.2. Site conditions
If Jiaguo can provide the following site conditions, it will be helpful for model selection.
3.2.1. Main original data of the project, including meteorological characteristics and environmental conditions
3.2.2. Basic earthquake intensity.
3.2.3. Installation and operation conditions, such as indoor or outdoor
3.2.4. Overview of system and related equipment, such as unit grade, etc.
3.3. Supply requirements
3.3.1. Special requirements for structure and materials (such as single barrel type, shell material, support position and quantity, etc.).
3.3.2. Specific requirements for valves and accessories, such as exhaust valve (electric, manual, regulating mode, etc.) and other types, specifications, quantities and relevant requirements of valves to be provided.
3.3.3. Any external requirements for measuring instruments, such as liquid level switch, liquid level measuring cylinder, etc.
3.3.4. Whether platform stairs are included. If platform stairs are required, specific requirements for platform escalators shall be put forward.
4. Scope of supply
The scope of supply includes product design, procurement, manufacturing, factory testing and on-site installation and commissioning guidance (the specific scope of supply can be increased or decreased according to customer demand).
Typical supplied devices and accessories are as follows:
4.1. Deaerator body.
4.2. Support (including anchor bolts and sliding parts)
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