CN204554773U - A kind of direct current cooker starts the hydrophobic system utilizing pressure flash vessel to reclaim - Google Patents

Abstract

The utility model discloses a kind of direct current cooker and start the hydrophobic system utilizing pressure flash vessel to reclaim, wherein, the entrance of the outlet Bonding pressure flash vessel of separator storage tank, first outlet of pressure flash vessel connects the entrance of high-pressure heater, the outlet of high-pressure heater connects the first entrance of oxygen-eliminating device, second outlet of pressure flash vessel connects the second entrance of oxygen-eliminating device, 3rd outlet of pressure flash vessel connects the 3rd entrance of oxygen-eliminating device, and the 4th outlet of pressure flash vessel connects the entrance of unit rhone.The utility model has the following advantages: do not have rotary machine equipment in (1) this system, thereby reduce associated dynamical system, control system, cooling system, saved construction investment, and in running, maintenance workload is also smaller simultaneously; (2) this system is a closed system, does not contact, there is not the contaminated problem of system with air; (3) this system and vacuum system do not contact, and there is not the impact on unit vacuum.

Description

A once-through boiler start-up drain recovery system using pressure expansion vessel

Technical field:

The utility model belongs to the field of electric power, and in particular relates to a system for recovering water from a once-through boiler by using a pressure expansion vessel to drain water.

Background technique:

Before the once-through boiler of the power station turns dry, the start-up separator will separate a part of saturated water, which is stored in the water storage tank of the separator. The separated water is called once-through boiler start-up drainage. At present, there are mainly the following ways to start the drainage of hydrophobicity.

The first is to use the boiler water circulation pump to recycle the start-up drain water to the inlet of the boiler economizer. This method mainly has the following shortcomings:

(1) During the working process of the start-up system, the working medium of the boiler water circulation pump has relatively high temperature and pressure, which requires high quality of the boiler water circulation pump. At present, the boiler water circulation pumps of our domestic super (super) critical boilers mainly rely on imports . The cost of imported boiler water circulation pumps is high and the order cycle is long. At present, thermal power generation is developing rapidly, and the supply of boiler water circulation pumps often cannot meet the needs of power plant construction.

(2) The cooling water quality of the motor chamber of the boiler water circulation pump is very high. In many power plants, the filter screen in the motor chamber has been blocked, resulting in high temperature of the boiler water pump motor and having to be shut down for maintenance.

(3) The boiler water circulation pump has high requirements on the reliability of the cooling water. In some power plants, due to the leakage of the cooling water in the motor chamber, the high-temperature water in the furnace entered the furnace water circulation pump motor chamber, causing the boiler water circulation pump motor coil to burn out. , had to shut down for maintenance.

(4) The maintenance of the boiler water circulation pump is troublesome. Since boiler water circulation pumps are mainly imported, many equipment suppliers put forward strict maintenance conditions, and it is difficult for power plants to meet the maintenance requirements. There used to be a power plant that airlifted the entire boiler water pump back to the factory to clean the filter due to clogging of the filter in the motor chamber, which took a month and wasted a lot of money.

The second method is to drain the priming drain to the atmosphere expander. This method mainly has the following shortcomings:

(1) The start-up drainage of the once-through boiler is saturated high-pressure water. After the expansion of the atmospheric expansion vessel, part of the exhaust steam through the atmospheric expansion vessel is discharged into the air, and part of the water that can be recovered can only be saturated water under normal pressure, resulting in Reduced waste of water and heat.

(2) The water vapor discharged into the air condenses and falls in the surrounding environment, causing pollution to the surrounding environment.

(3) If the water quality of the saturated water in the atmospheric expansion vessel is qualified, it needs to be discharged into the condenser. However, due to the high temperature of the recycled water, after entering the condenser, the temperature of the condensed water will increase, which will reduce the efficiency of the unit. Affect the safe operation of condensate polishing.

(4) The water in the atmosphere expander must be pumped into the condenser through the drain pump, which increases the investment.

(5) The condenser is connected to the atmosphere expander. Due to internal leakage of the valve and other reasons, the vacuum of the condenser is affected, the efficiency of the unit operation is reduced, and even the safe operation of the unit is affected.

(6) The atmosphere expander is not closed, and the dust in the air will inevitably enter the atmosphere expander, which increases the secondary pollution of the start-up drainage. If contaminated water enters the condenser, it can contaminate the thermal system.

Utility model content:

The purpose of the utility model is to provide a system for recovery of once-through boiler start-up drainage using pressure expansion vessel in view of the deficiency of the prior art of drainage recovery for once-through boiler startup.

In order to achieve the above object, the utility model adopts the following technical solutions to achieve:

A system for recovering water from a once-through boiler by using a pressure expansion vessel, including a separator water storage tank, a pressure expansion vessel, a deaerator, a high-pressure heater and a unit drainage tank; wherein,

The outlet of the separator water storage tank is connected to the inlet of the pressure expansion vessel, the first outlet of the pressure expansion vessel is connected to the inlet of the high-pressure heater, the outlet of the high-pressure heater is connected to the first inlet of the deaerator, and the second outlet of the pressure expansion vessel is connected to the deaerator. The second inlet of the oxygenator, the third outlet of the pressure expansion vessel are connected to the third inlet of the deaerator, and the fourth outlet of the pressure expansion vessel is connected to the inlet of the unit drainage tank.

The further improvement of the utility model is that a water level control valve of the separator water storage tank is arranged on the pipeline connecting the outlet of the separator water storage tank to the inlet of the pressure expansion vessel, and a water level control valve of the separator water storage tank is arranged on the pipeline connecting the first outlet of the pressure expansion vessel to the inlet of the high-pressure heater. There is a main valve for adjusting the water level of the pressure expansion vessel, and the outlet of the high-pressure heater is connected to the first inlet of the deaerator. The pipeline of the second inlet is provided with an auxiliary valve for regulating the water level of the pressure expansion vessel, and the pipeline connecting the third outlet of the pressure expansion vessel to the third inlet of the deaerator is provided with a pressure regulating main valve of the pressure expansion vessel, and the fourth pressure expansion vessel A regulating valve from the pressure expansion vessel to the unit drainage tank is arranged on the pipeline where the outlet is connected to the inlet of the unit drainage tank.

The further improvement of the utility model is that it also includes an auxiliary steam header, wherein the third outlet of the pressure expansion vessel is divided into two strands, one is connected to the third inlet of the deaerator, and the other is connected to the inlet of the auxiliary steam header .

The further improvement of the utility model is that the pressure expansion vessel pressure regulating auxiliary valve is arranged on the pipeline connecting the third outlet of the pressure expansion vessel to the inlet of the auxiliary steam header.

Compared with the prior art, the utility model has the following advantages:

The utility model is a system for recovering water from once-through boilers by using pressure expansion vessels, which has the following advantages: (1) There is no rotating mechanical equipment in the system, thereby reducing the power system, control system, and cooling system related to it, saving energy. The construction investment is reduced, and the maintenance workload during operation is relatively small; (2) the system is a closed system, which has no contact with the atmosphere, and there is no problem of system contamination; (3) the system is not connected with the vacuum system, There is no effect on unit vacuum.

Description of drawings:

Fig. 1 is a structural block diagram of a system for recovering water from a once-through boiler using pressure expansion vessel in the utility model.

Detailed ways:

Below in conjunction with accompanying drawing and embodiment the utility model is described in further detail.

As shown in Figure 1, the utility model is a system for recovery of drainage by means of a pressure expansion vessel for starting a once-through boiler, including a separator water storage tank 1, a pressure expansion vessel 3, a deaerator 7, a high-pressure heater 9 and a unit drainage tank 11; in,

The outlet of the separator water tank 1 is connected to the inlet of the pressure expansion vessel 3, the first outlet of the pressure expansion vessel 3 is connected to the inlet of the high-pressure heater 9, and the outlet of the high-pressure heater 9 is connected to the first inlet of the deaerator 7, and the pressure expansion vessel The second outlet of 3 is connected to the second inlet of deaerator 7, the third outlet of pressure expansion vessel 3 is connected to the third inlet of deaerator 7, and the fourth outlet of pressure expansion vessel 3 is connected to the inlet of unit drainage tank 11.

Further, the separator water storage tank water level control valve 2 is arranged on the pipeline connecting the outlet of the separator water storage tank 1 to the inlet of the pressure expansion vessel 3, and the first outlet of the pressure expansion vessel 3 is connected to the pipeline of the inlet of the high-pressure heater 9. There is a main valve 8 for adjusting the water level of the pressure expansion vessel, the outlet of the high-pressure heater 9 is connected to the first inlet of the deaerator 7, and the pipeline from the high-pressure heater to the drain regulating valve 12 of the deaerator is arranged, and the second outlet of the pressure expansion vessel 3 The pipeline connected to the second inlet of the deaerator 7 is provided with a pressure expansion vessel water level regulating auxiliary valve 13, and the pipeline connecting the third outlet of the pressure expansion vessel 3 to the third inlet of the deaerator 7 is provided with a pressure expansion vessel pressure regulator. The main valve 6 and the fourth outlet of the pressure expansion vessel 3 are connected to the inlet of the unit drainage tank 11. A regulating valve 10 is provided from the pressure expansion vessel to the unit drainage tank.

In addition, the utility model also includes an auxiliary steam header 5, wherein the third outlet of the pressure expansion vessel 3 is divided into two strands, one is connected to the third inlet of the deaerator 7, and the other is connected to the auxiliary steam header 5. Entrance. Wherein, on the pipeline connecting the third outlet of the pressure expansion vessel 3 to the inlet of the auxiliary steam header 5, a pressure expansion vessel pressure regulating auxiliary valve 4 is arranged.

In order to further understand the utility model, an explanation is made to its working process now.

When working, the once-through boiler starts to drain and collects water in the separator water storage tank 1, and the water in the separator water storage tank 1 is discharged to the pressure expansion vessel 3 through the water level control valve 2 of the separator water storage tank to expand and reduce pressure, generating the same pressure as the steam side of the high-pressure heater. Matching saturated water and steam; saturated water enters the steam side of the high pressure heater 9 through the water level regulating main valve 8 of the pressure expansion vessel, absorbs heat through the high pressure heater 9, and returns to the deaerator through the high pressure heater to the drain regulating valve 12 of the deaerator device 7; the steam enters the deaerator 7 through the pressure expansion vessel pressure regulating main valve 6;

The water produced by the pressure expansion vessel 3 that cannot be completely recovered by the high-pressure heater 9 is directly discharged to the deaerator 7 through the secondary valve 13 for adjusting the water level of the pressure expansion vessel. The steam generated by the pressure expansion vessel 3 that cannot be completely recovered by the deaerator 7 is directly discharged to the auxiliary steam header 5 through the pressure expansion vessel pressure regulating auxiliary valve 4 .

During the start-up process, the unqualified water is discharged to the unit drainage tank 11 through the pressure expansion vessel 3 through the pressure expansion vessel to the regulating valve 10 of the unit drainage tank.

The pressure expansion vessel 3 expands and depressurizes the water in the separator water storage tank 1 to saturated water and saturated steam matching the steam side pressure of the high pressure heater 9; Heater 9 vapor side pressure. The flow rate, pressure and temperature of the water in the separator water storage tank 1 are constantly changing during the start-up process of the once-through boiler. When designing the pressure expansion vessel, it is necessary to calculate the water in the separator water storage tank 1 under various pressure conditions during the start-up process. Expanding and depressurizing to the expansion multiple n and expansion volume flow Q of the rated pressure on the steam side of the high pressure heater 9, select the maximum expansion multiple n _max and the maximum expansion volume flow Q _max to design the pressure expansion vessel. The pressure expansion vessel 3 must ensure that under various working conditions during the startup process of the once-through boiler, the water in the separator water storage tank 1 can be expanded and reduced to below the rated pressure of the steam side of the high-pressure heater 9, so as to ensure that the recovery process of the unit safe operation.

Among them, the expansion factor n is calculated according to the following steps:

1) Find out the enthalpy value h1, specific volume v1, and saturation temperature t1 of the water in the water storage tank 1 of the separator under a certain working condition according to the thermodynamic property table of water vapor, and find out the saturated water temperature at the rated pressure of the steam side of the high-pressure heater 9 Enthalpy h2, specific volume v2 of saturated water, temperature of saturated water, enthalpy h3 of saturated steam, specific volume v3 of saturated steam;

2) Assuming that the water in the separator water storage tank is expanded and depressurized to produce x share of saturated water and 1-x share of saturated steam, then: h1=h2*x+h3*1-x, by giving x value Trial calculation to ensure that the above equation holds true, and finally determine the value of x;

3) Using the formula n=(x*v2+(1-x)*v3)/v1 to calculate the expansion factor.

Follow the steps below to calculate the volume flow Q after capacity expansion:

a) Find out the enthalpy value h1, specific volume v1, and saturation temperature t1 of the water in the separator water storage tank 1 under a certain working condition according to the thermodynamic properties table of water vapor, and find out the saturated water temperature at the rated pressure of the steam side of the high-pressure heater 9 Enthalpy value h2, specific volume v2 of saturated water, temperature of saturated water, enthalpy value h3 of saturated steam, specific volume v3 of saturated steam. According to the boiler design parameters, determine the start-up drain q generated by the separator under this working condition;

b) Assuming that the water in the water storage tank of the separator is expanded and depressurized to produce x proportion of saturated water and 1-x proportion of saturated steam, then: h1=h2*x+h3*1-x. By giving a trial calculation of the value of x, the above equation is guaranteed to be true, and the value of x is finally determined;

c) Using the formula Q=q*(x*v2+(1-x)*v3), calculate the volumetric flow rate after capacity expansion.

In addition, the flow area of the pressure expansion vessel is n _max times the flow area of the pipeline from the separator water storage tank to the pressure expansion vessel, and the volume is selected to be no less than 1 minute under the condition of the maximum expansion volume flow rate Q _max .

Example:

The specific implementation of the utility model will be described below by taking the start-up drainage recovery of a once-through boiler of a 660MW supercritical unit in a power plant as an example.

Generally, a 660MW supercritical thermal power unit will be designed with three levels of high-pressure heaters, that is, No. 1 high-pressure heater, No. 2 high-pressure heater, and No. 3 high-pressure heater. The drainage of No. 1 high-pressure heater is discharged to No. 2 high-pressure heater, the drainage of No. 2 high-pressure heater is discharged to No. 3 high-pressure heater, and the drainage of No. 3 high-pressure heater is discharged to the deaerator. The high-pressure heater in the utility model refers specifically to the high-pressure heater that drains the water to the deaerator, which is No. 3 high-pressure heater in this example.

According to the boiler design parameters, the boiler feed water flow rate is 520t/h, the separator outlet steam pressure is 10MPa, and the temperature is 310°C when the once-through boiler is converted from dry to wet state;

According to the design parameters of the unit, the steam supply flow rate of the deaerator under the maximum load condition of the unit is determined to be 182t/h, the pressure is 1.1MPa, and the temperature is 355°C;

According to the design parameters of the unit, it is determined that under the maximum load condition of the unit, the flow rate of steam side drainage from No. 1 high-pressure heater to No. 2 high-pressure heater is 142t/h, the pressure is 7.2MPa, and the temperature is 263°C;

According to the design parameters of the unit, the flow rate, pressure 4.7MPa, and temperature 220°C of the drain on the steam side of No. 2 high-pressure heater to No. 3 high-pressure heater are determined under the maximum load condition of the unit;

According to the design parameters of the unit, the flow rate from the No. 3 high-pressure heater to the deaerator drain is 396t/h, the pressure is 2.26MPa, and the temperature is 189°C under the maximum load condition of the unit;

According to the design parameters of the boiler, the steam flow rate at the outlet of the separator and the saturated water flow rate of the water storage tank are determined under different pressures of the once-through boiler. Calculate the expansion volume and expansion multiple required for the isenthalpic expansion and decompression of saturated water under different pressures (higher than 2MPa) to a pressure of 2.0MPa. The calculation results are shown in Table 1:

Table 1 Summary of calculation results of saturated water capacity expansion

Start separator water tank pressure (MPa) 3 4 5 6 7 8 9 10 Once-through boiler main steam flow (t/h) 157 210 265 320 370 420 470 520 Start hydrophobic flow (t/h) 363 310 255 200 150 100 50 0 Start-up hydrophobic saturated water volume (km ³ /h) 0.443 0.387 0.329 0.264 0.202 0.138 0.071 0 Pressure inside pressure expander (MPa) 2 2 2 2 2 2 2 2 Water flow in pressure expansion vessel (t/h) 344 281 222 168 122 78 38 0 Steam flow in pressure expander (t/h) 19 29 33 32 28 twenty two 12 0 Saturated water volume (km ³ /h) 0.385 0.3 0.228 0.166 0.116 0.073 0.034 0 Vapor volume (km ³ /h) 0.098 0.298 0.429 0.522 0.539 0.464 0.287 0 Pressure expander volume (km ³ /h) 0.483 0.578 0.657 0.688 0.655 0.537 0.321 0 Expansion multiple 1.09 1.49 2 2.61 3.23 3.89 4.52 0

It can be seen from the above table that the higher the pressure, the greater the expansion factor. When the pressure is 9MPa, the maximum expansion factor is 4.52. However, due to the increase in pressure, the amount of hydrophobic water to start decreases, and the volume that needs to be expanded decreases instead. When the start-up pressure of the separator is 6MPa, the volume of the pressure expansion vessel required is the largest, which is 0.688 (km ³ /h), and its 1-minute volume is 11.47m ³ .

The flow area of the pressure expansion vessel is selected to be 5 times the flow area of the drain pipe of the separator tank, and the volume is 12m ³ (that is, the maximum volume in 1 minute) to design the pressure expansion vessel.

The water drain from the water storage tank of the steam-water separator is connected to the pressure expansion vessel after passing through the water level control valve of the water storage tank of the separator. The drainage of the pressure expansion vessel is connected to the steam side drain pipe from No. 2 high-pressure heater to No. 3 high-pressure heater, and the flow rate is designed to be 310t/h. One way is connected to the water supply pipeline of the deaerator, and the flow rate is designed to be 520t/h. One way is connected to the drainage tank of the unit, and the flow rate is designed to be 520t/h. The exhaust steam of the pressure expansion vessel is connected to the steam supply pipeline of the deaerator, and the flow rate is designed to be 40t/h. One way is connected to the auxiliary steam header of the unit, and the flow rate is designed to be 40t/h.

The pressure expansion vessel shall consider the energy dissipation measures for water entering at 10MPa pressure, and shall have safety doors, temperature, pressure, and water level measuring points; other unmentioned design factors of the pressure expansion vessel shall comply with the design standards of electric pressure vessels and pipelines.

Design a regulating valve on the pipeline from the pressure expansion vessel to the deaerator, high-pressure heater, auxiliary steam header, and unit drainage tank, and use it to adjust the flow of water entering the high-pressure heater, and the flow of water and steam entering the deaerator The flow rate, the steam flow rate entering the auxiliary steam header, and the water flow rate entering the drainage tank of the unit are further used to control the pressure and water level of the pressure expansion vessel.

During the start-up process of the unit, if the water quality is unqualified, the water will be discharged to the unit drainage tank through the pressure expansion vessel;

When the pressure in the start-up separator is less than 2MPa, the water in the water storage tank of the start-up separator enters the deaerator through the pressure expansion vessel; the steam in the pressure expansion vessel enters the deaerator through the steam pipe;

When the pressure in the start-up separator is greater than or equal to 2MPa, after the water in the water storage tank of the start-up separator is expanded and depressurized through the pressure expansion vessel, the water enters the No. 3 high-pressure heater through the pressure expansion vessel (excess water enters the deaerator); The steam in the expansion vessel enters the deaerator through the steam pipeline (excess steam enters the auxiliary steam system).

Claims (4)

1. A system for once-through boilers to start draining water and utilize pressure expansion vessels to recover, is characterized in that: comprise separator water storage tank (1), pressure expansion vessel (3), deaerator (7), high-pressure heater (9) and Unit drainage groove (11); wherein, The outlet of the separator water storage tank (1) is connected to the inlet of the pressure expansion vessel (3), the first outlet of the pressure expansion vessel (3) is connected to the inlet of the high-pressure heater (9), and the outlet of the high-pressure heater (9) is connected to the oxygen removal The first inlet of the device (7), the second outlet of the pressure expansion vessel (3) is connected to the second inlet of the deaerator (7), and the third outlet of the pressure expansion vessel (3) is connected to the second outlet of the deaerator (7). Three inlets, the fourth outlet of the pressure expansion vessel (3) is connected to the inlet of the unit drainage tank (11). 2. A kind of once-through boiler start-up drainage system according to claim 1, which utilizes a pressure expansion vessel to recover, is characterized in that: the outlet of the separator water storage tank (1) is connected to the pipeline of the inlet of the pressure expansion vessel (3). The water level control valve (2) of the separator water storage tank, the first outlet of the pressure expansion vessel (3) is connected to the inlet of the high pressure heater (9) and is provided with a pressure expansion vessel water level regulating main valve (8), a high pressure heater ( 9) The outlet of the outlet is connected to the pipeline of the first inlet of the deaerator (7) to be provided with a high-pressure heater to the drain regulating valve (12) of the deaerator, and the second outlet of the pressure expansion vessel (3) is connected to the deaerator (7 ) is provided with a pressure expansion vessel water level regulating auxiliary valve (13) on the pipeline of the second inlet of the pressure expansion vessel (3), and a pressure expansion vessel is provided on the pipeline connecting the third outlet of the pressure expansion vessel (3) to the third inlet of the deaerator (7) The pressure regulating main valve (6), the fourth outlet of the pressure expansion vessel (3) is connected to the inlet of the unit drainage tank (11) with a pressure expansion vessel to the unit drainage tank regulating valve (10). 3. A system according to claim 1, wherein a once-through boiler starts draining water and utilizes a pressure expansion vessel to recover, and is characterized in that: it also includes an auxiliary steam header (5), wherein the third outlet of the pressure expansion vessel (3) is divided into There are two strands, one is connected to the third inlet of the deaerator (7), and the other is connected to the inlet of the auxiliary steam header (5). 4. A system according to claim 3 for starting water drainage of a once-through boiler and recovering by means of a pressure expansion vessel, characterized in that: the third outlet of the pressure expansion vessel (3) is connected to the pipeline of the inlet of the auxiliary steam header (5) A pressure expansion vessel pressure regulating auxiliary valve (4) is provided.