全部
  • 全部
  • 产品管理
  • 新闻资讯
  • 介绍内容
  • 企业网点
  • 常见问题
  • 企业视频
  • 企业图册
+
  • u=1096867118,3703006433&fm=26&gp=0.jpg

High temperature and high pressure deaerator

key word:Heat exchange element


Product description

High temperature and high pressure deaerator

 

1. Introduction

1.1. Purpose

The main function of deaerator is to remove dissolved oxygen and other gases from boiler feed water, so as to prevent corrosion of thermal equipment and deterioration of heat transfer, and ensure safe and economic operation of thermal equipment. The boiler feed water is heated to saturation temperature under deaerator operation pressure by steam extraction from low pressure side of steam turbine and other drainage and residual steam, so as to improve thermal efficiency of unit,

1.2. Model meaning

1.2.1. Head deaerator

1.2.1.1. Deaerator.

G-C-**

G-S high pressure

C -- Code of deaerator

**-------Deaerator output (t/h)

1.2.1.2. Deaeration water tank

G-S-**

G --- high voltage

S -- water tank

**-------Working volume of water tank (m3)

1.2.2. Headless deaerator (integrated deaerator)

G-C-** –G-S-##

G --- high voltage

C --- deaeration code

**------Deaerator output (t/h)

G -------- high voltage

S --- water tank

##-------------Working volume of water tank (m3)

1.3. Structural features

1.3.1. Structural form. It can be divided into physical Deaerator and chemical deaerator. Pressure type thermal deaerator is widely used.

At present, the head Deaerator and headless deaerator are the most commonly used in power plants in China. The head deaerator, that is, the deaerator and the water tank, can be divided into spray type, packing type, water spraying plate type, spray packing type, spray steam spraying disc type, spray water spraying disc type and other deaerator according to different internal deaeration elements. Spray and packing should be combined with other forms to achieve better deaeration effect. The deaerator for 300MW and above units is mostly spray water dish.

1.3.1.1. spray sprinkling disc deaerator. The spray spray deaerator commonly has two forms: vertical and horizontal (see Figure 30-1). Horizontal spray water drain disc deaerator is lying on the deaeration water tank. The deaerator cylinder is also arranged horizontally along the axis of the water tank body, which is beneficial to the layout of the intake nozzle and the total height of the deaeration equipment, as well as reducing the opening diameter of the deaerator on the water tank, reducing the stress of the saddle shaped weld seam and improving the stress condition of the water tank. Compared with the vertical, it has the advantages of small space, safe and reliable connection with the water tank, and easy to arrange the electrical system. Figure 30-2 shows the combination of Deaerator and deaerator water tank.

1.3.1.2. Headless deaerator. Headless deaerator is a new design which combines the conventional deaerator with the upper Deaerator and the lower deaerator water tank. The former Deaerator and the water tank are specially designed to form an integrated deaerator which can both deaerate and store water. It is also called headless deaerator because the former deaerator with deaeration function is incorporated into the original water tank Head deaerator. Figure 30-3 shows the basic model of the headless deaerator.

1.3.2. Structure description:

1.3.2.1. spray spray disc deaerator (section is shown in Fig.30-4 ). The spray dewatering box type deaerator is divided into two parts, the upper space is the spray deaeration section, and the lower part is the deep deaeration section with the water spraying box. The water atomization depends on the pressure of the condensate pump, and the constant speed nozzle is used to spray the condensate into mist. Atomization of water droplets in the spray layer can increase the surface tension and remove the residual oxygen. Therefore, the deoxygenation effect can not be achieved by the spray deoxygenation section, and deep deoxygenation stage is needed to make up for its deficiency. The deep deoxidization of deaerator is accomplished by the drip tray. The heating steam enters from below. In the rising process, most of the steam is exothermic and condensed into water, which enters the deaeration water tank for storage together with the deaerated water. The remaining non condensing steam and the gas separated from the water are discharged from the top.

After secondary deaeration, the effluent quality of deaerator is ensured. Practice has proved that the spray dewatering box deaerator has good deaeration effect, and the oxygen content of the effluent is generally less than 0.007mg/L, which reaches the minimum value of boiler water quality standards at home and abroad.

1.3.2.2. Headless deaerator. The headless deaerator mainly consists of spray deoxygenation section, deep deoxygenation section and water storage. The spray deaeration section is to pour condensate water into the upper chamber of the shell, and through constant velocity nozzle, under the action of pressure difference, the condensed water is ejected through the conical membrane, and then enters the spray deaeration section. In this section, water and steam are fully contacted to spray and deoxidize. Most of the non condensing gases are removed in this section and discharged into the atmosphere through the exhaust pipe. The function of the deep deaeration section is to spray the condensate sprayed on the water surface of the deaerator water storage section after deaeration, and to arrange the steam pipe to the bottom of the storage section of the deaerator to heat the feed water and continuously boil it, so as to complete a very deep deep deaeration process, so that the oxygen content of the boiler feed water is not greater than 5ppb.

1.3.3. Description of important parts:

1.3.3.1. Nozzle. The nozzle is the main deaerator for spray deoxygenation. The key of atomization is the degree of water atomization, which depends on the structure of the nozzle. Although there are many types of nozzles, the principle of atomization is basically the same.

There are several kinds of nozzles commonly used in power plants.

Swirl core nozzle (see Fig. 30-5): the atomization of this kind of nozzle is better at rated output; however, at low load, due to less water and low pressure drop, the atomization is obviously deteriorated.

Jet swirl nozzle (see Fig. 30-6): when the inlet pressure is small, the outlet rotating force is very small, and the diameter of the water droplet ejected is large; when the inlet pressure increases, the spraying situation is obviously improved, the outlet rotating force is increased, and the droplet diameter is smaller, and the spraying area and height can also be greatly increased. The water is in a fine mist state, and the spray angle is close to 90 °.

Annular nozzle (see Fig. 30-7): there is a rectangular inclined hole every 60 ° on the circumference of the nozzle chamber. Condensate enters the nozzle chamber along the tangent direction of the included angle, rotates, and then sprays out in the form of mist through the nozzle hole.

Spring nozzle: also known as constant speed nozzle. See Fig. 30-8 for structure

All kinds of nozzles can get good atomization effect only when the operating condition is under the inlet pressure required by the design. When the load of deaerator decreases, the water pressure entering the nozzle will decrease, which will affect the atomization effect, especially for the nozzle with central water hole. This problem can be solved by using spring nozzle. When the inlet pressure changes, the spring will expand and expand, and the spring will affect the corresponding valve disc or valve cake, which will change the cross-sectional area of the nozzle outlet. Therefore, good atomization effect can be obtained when the load changes. At present, many deaerator often use spring nozzle.

1.3.3.2. Drip tray. The sprinkling box (see Fig. 30-9) is the main part of the deep deaeration of the spray water deaerator. The condensate ejected from the atomization area flows into the lower channel steel from both sides of the upper channel steel on the drenching pan box. The upper and lower channel steel are staggered with each other. Because in the drenching pan box, the water flows from top to bottom and the heating steam flows from bottom to top, countless water curtains can be formed through one layer of drenching pan box, so that the contact area between the condensate and steam can reach the maximum value, so as to reduce the pressure Get the best heat exchange.


1.3.4. Description of important characteristics:

1.3.4.1. Operation of deaerator. There are two operation modes of deaerator: one is that under any working condition, the working pressure of deaerator must maintain a certain constant pressure, which is called constant pressure operation deaerator; the other is that the operating pressure of deaerator changes with the change of extraction pressure of group load (working condition), which is called sliding pressure operation deaerator.

Constant pressure operation: the deaerator operating at constant pressure shall keep the pressure and temperature of the deaerator stable during operation, and the water level shall be ± 200 mm of the normal water level. Steam and water balance pipes with sufficient diameter and capable of balancing shall be installed between Deaerator in parallel operation to make their working conditions consistent. In order to ensure the safety and reliability of constant pressure operation of deaerator, the rated working pressure of constant pressure operation can be realized by heating steam pressure regulating valve. The main advantages of constant pressure deaerator are stable deaeration effect and good system safety. However, due to throttling loss of heating steam, the operation economy is poor.

Sliding pressure operation: during the sliding pressure operation of deaerator, since it is not necessary to maintain the constant pressure of deaerator, the valve on the steam extraction pipeline of deaerator is fully open, and the pressure of deaerator can be changed randomly according to the load and extraction pressure, without throttling loss of extraction steam pressure at constant pressure of deaerator, thus improving the thermal efficiency; At the same time, the steam extraction points of the steam turbine are reasonably distributed, which simplifies the system and improves the economy of the unit and the regenerative system.

1.3.4.2. Adjustment of deaerator. At the initial stage of deaerator operation, reasonable adjustment should be made to obtain the best operation condition. For the deaerator newly put into operation or after transformation, adjustment test should be carried out to identify its design characteristics; When the operation mode of deaerator is changed or the steam source and water source are changed, adjustment test shall be carried out to determine and improve the new operation mode. In addition, when the operation of deaerator deteriorates and the dissolved oxygen content in effluent can not meet the specified standard, adjustment test shall also be conducted to find out the causes and take countermeasures. According to the different conditions of various deaerator, the test contents can be selected purposefully according to the operation conditions required in the design of deaerator. The optimal operation conditions under the oxygen content of effluent in accordance with the standard can be obtained by adjusting the test.

Maintenance of deaerator. Maintenance is an effective measure to improve the service life of deaerator. Regular maintenance of deaerator is generally divided into external inspection, internal and external inspection and hydrostatic test. According to the regulations of "safety technical regulations for pressure deaerator of power station", the external inspection of deaerator should be carried out in operation at least once a year; the internal and external inspection can be carried out in combination with unit overhaul, at least once every 3-6 years; hydraulic test should be carried out according to the safety condition of deaerator combined with unit overhaul, and the interval period should be at least once every 10 years.

 

2. Main technical parameters and product appearance

2.1. Main technical parameters

2.1.1. Deaeration index of feed water. According to GB/T 12145-2008 "quality of water vapor for thermal power generating units and steam power equipment", the dissolved oxygen content in boiler feed water shall meet the specified index in table 30-1.

Table 30-1 standard of dissolved oxygen in boiler feed water

Furnace type Drum boiler Once through furnace
Boiler pressure (MPa) 3.8~5.8 5.9~12.6 12.7~15.6 15.7~18.3 5.9~183
Dissolved oxygen (ug/L) 15 7 7 7 27

2.1.2. Main characteristic parameters. The main characteristic parameters of thermal deaerator are output, design pressure, working pressure, design temperature, outlet water temperature, etc.

2.1.2.1. Output of deaerator. The output of deaerator refers to the amount of water supplied by the outlet pipe of deaerator meeting the specified dissolved oxygen content in unit time, which can be divided into rated output, maximum output and minimum output.

2.1.2.2. Design pressure. The design pressure shall be determined according to the highest working pressure of Deaerator in operation. At present, in many power plants, the design pressure of deaerator under constant pressure operation should not be less than 1.3 times of rated working pressure; the design pressure of deaerator under sliding pressure operation should not be less than 1.25 times of regenerative extraction steam pressure of deaerator under maximum continuous output power of steam turbine.

2.1.2.3. Working pressure. The working pressure refers to the gauge pressure produced by the top of Deaerator in the normal working process, and its value is determined by economic and technical comparison and practical requirements.

2.1.2.4. Design temperature. The design temperature of deaerator shall not be lower than the larger value of the following two temperatures: ① the regenerative extraction steam temperature adopted by deaerator when the steam turbine is operating under the maximum continuous output power; ② the temperature of auxiliary steam used by the deaerator during startup or low load operation.

2.1.2.5. The design temperature of the water tank shall not be lower than the saturation temperature of the medium under the maximum working pressure, and shall not be lower than 205 ℃.

2.1.2.6. Outlet water temperature. Outlet water temperature refers to the water temperature at the outlet of deaeration water tank. The deaerator is a hybrid heater. Under the steady-state operation condition, the working medium in the deaerator is always in the saturation state under the rated working pressure, and the water temperature in the water tank is average stable. Therefore, the water temperature at the outlet of the water tank is equal to the saturation temperature corresponding to the rated working pressure of the deaerator.

2.1.3. Main technical indicators (see table 30-2).

Table 30-2 main technical indexes of deaerator

Model Capacity Design pressure Design temperature Nozzle pressure drop Weight Deaeration water tank configuration Remarks
(t/h) (MPa) (℃) (MPa) t Model Effective volume
(m3)
GC-1080 1080 1 350 0.014 23 GS-150 150 300MW Unit
GC-2400 2400 1.4 371 0.0588 55.7 GS-235 235 600 MW Supercritical Unit
GC-2793 2793 1.5 380 0.014 56 GS-308 308 Equipped with 1000MW supercritical unit

2.2. Product appearance (see figure 30-10 and table 30-3)

Table 30-3 overall dimension of deaerator   (mm)

Model L W H
GC-1080 7356 2942 3590
GC-2400 10 300 2942 3690
GC-2793 15562 2908 3962

 

3. Selection method

The technical data provided by the equipment purchaser are as follows:

3.1. Design and operating conditions

3.1.1 system overview and related equipment: steam turbine model and data of various working conditions; deaerator form parameters; deaerator operation parameters: unit operation mode.

3.1.2. Original data of the project (meteorological characteristics and environmental conditions).

3.1.3. Operation mode of deaerator:  deaerator equipment layout; deaerator form and operation mode; condensate water quality into deaerator

3.2. Technical conditions:

3.2.1. Equipment performance requirements,

3.2.2. Equipment manufacturing requirements

3.2.3. Equipment material requirements

3.2.4. Instrument control requirements.

3.2.5. Relevant standards (design standards, material standards, pipeline standards, manufacturing standards, quality inspection standards, paint, packaging, transportation standards, seismic standards)

3.2.6. Equipment performance guarantee, test and requirements

 

4. Scope of supply

4.1. Deaerator body, including manhole and support

4.2. Constant speed nozzle,

4.3. Valves and accessories.

4.4. Instrument control elements.

4.5. Platform and escalator.

4.6. Special tools.

4.7. Spare parts,

4.8. Completion data used by the owner for equipment acceptance, safety review, installation, commissioning and maintenance.

Among them, 4.2 ~ 4.7 can be manufactured, purchased and configured by the supplier, or purchased or configured by itself.