JPH10267212A - Variable pressure once through boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable highly efficient circulation in a boiler without increasing the amount of heated steam to a deaerator by connecting a water separator drain system to the deaerator to achieve an effective utilization of a drain. SOLUTION: A variable pressure once through boiler 22 has a steam generation system 30 which reaches an evaporator 5 via a boiler feed pump 11 and a fuel economizer 4 from a deaerator 7 and a water separator drain system 31 which is connected to the steam generation system 30 through a water separator 1 and has a water separator drain tank 2 and a condenser 6. A high temperature drain is sent to the deaerator 7 from the water separator drain tank 2 to raise the temperature of the feed water stored in a water storage tank 7B of the deaerator 7, that is, enabling recovery of heat of the drain in the deaerator 7. This constitution enables raising of the temperature of the boiler feed water without requiring a large amount of heated steam for raising the pressure of the deaerator 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a once-through boiler for performing a variable pressure operation, and more particularly to a once-through boiler using a water separator drain system.

[0002]

2. Description of the Related Art FIG. 2 is a view for explaining an evaporation generation system and a water separator drain system of a general variable-pressure once-through boiler. As shown in FIG. 2, a variable-pressure once-through boiler 20 (hereinafter simply referred to as "boiler") is used. 20 ") is a water separator 1, a water separator drain tank 2,
Boiler circulation pump 3, economizer 4, evaporator 5, condenser 6,
It comprises a deaerator 7 and a boiler feed pump 11. In the figure, reference numeral 8 denotes a heating steam supply path, and 9
Indicates a boiler water supply channel.

Here, the deaerator 7 removes dissolved gas from feed water heated by the heating steam supplied from the heating steam supply passage 8, and has a feed water deaerator 7A and a water storage tank 7B. After the supply water is degassed by bringing heated steam into contact with the water supply deaerator 7A, the deaerated water supply is stored in the water storage tank 7B.

A boiler feed pump (BFP) 11
Pressurizes the water supplied from the deaerator 7, and pressurized boiler water is supplied through a boiler water supply passage 9. The boiler water is supplied from a drain supplied from a boiler circulation pump 3 described later. And come to join. Thereafter, the boiler feedwater is heated by the economizer 4 and converted into steam by the evaporator 5, and the steam is sent to the superheater (not shown) via the water separator 1.

Further, the water separator 1 separates a mixture of steam and water from the evaporator 5, and sends the steam from the evaporator 5 to the superheater, as described above, while the water from the evaporator 5 does not become steam. (Drain) is returned to the water separator drain tank 2 at the subsequent stage. The water separator drain tank 2 stores the drain from the water separator 1. As described above, the drain is a water separator drain system (water separator 1 and water separator drain tank 2).
Sent by

Further, a boiler circulation pump (BCP) 3
Pressurizes the drain from the water separator drain tank 2 and supplies the pressurized drain to the boiler water supply passage 9 as described above in a so-called wet operation range from the start of the variable pressure once-through boiler 20 to a low load. Thereby, heat recovery of the boiler is performed. That is, since the drain from the water separator drain tank 2 is high-temperature water, the temperature of the boiler feedwater sent to the economizer 4 can be increased by joining the pressurized drain with the boiler feedwater, and consequently, The amount of steam sent to the superheater via the economizer 4 and the evaporator 5 can be increased. That is, the steam sent from the superheater to the turbine (not shown) can be increased, so that the turbine can be operated more efficiently.

Further, the condenser 6 cools the steam after finishing the work in the turbine and returns the steam to water, and the steam sent from other parts (for example, as shown in FIG. 2). The drain from the water separator drain tank 2 is received and returned to water. The water returned by the condenser 6 is used again as water supply to the deaerator 7. Thus, the water used in the variable pressure once-through boiler 20 is efficiently circulated by the boiler circulation pump 3.

With the above configuration, when the dissolved gas is removed from the feed water heated by the heating steam from the heating steam supply path 8 in the deaerator 7, the gas is pressurized by the boiler feed pump 11, and this pressurization is performed. The boiler feedwater merges with the drain sent from the boiler circulation pump 3 and saves energy.
, And converted into steam by the evaporator 5 and sent to the superheater (not shown) via the water separator 1.

At this time, the water (drain) which has not been turned into steam in the evaporator 5 is sent to the water separator drain tank 2 and then pressurized by the boiler circulation pump (BCP) 3 to join the boiler feed water again. . In this way, the water supplied from the deaerator 7 circulates in the boiler 20, thereby increasing the temperature and improving the boiler efficiency.

[0010]

However, the variable-pressure once-through boiler 2 provided with the boiler circulation pump 3 as described above.
At 0, the boiler feed water from the boiler feed pump 11 is supplied by the boiler circulation pump 3 to the economizer 4, the evaporator 5,
Since the water is circulated (boiler circulated) in the water separator 1 and the water separator drain tank 2, there is an advantage that heat can be recovered by high-temperature drain (although the heat efficiency for converting into steam is good), Since the boiler circulation pump 3 is provided, there is a problem in that the boiler is expensive and the cost of the entire boiler is increased.

Therefore, as shown in FIG. 3, a variable-pressure once-through boiler 21 having no boiler circulation pump has been considered, but this type of variable-pressure once-through boiler 21 (this type of variable-pressure once-through boiler 21 is also simply referred to as Boiler 21), the boiler feedwater which does not receive the pressurized drain from the boiler circulation pump directly flows into the economizer 4, that is, there is no heat recovery by the boiler circulation pump in the wet operation range. Therefore, when the boiler feedwater temperature is the same as that of the boiler (boiler with boiler circulation pump) 20 shown in FIG. 2, the boiler feedwater temperature sent to the inlet of the economizer 4 is lower than that of the boiler with boiler circulation pump 20. It will get worse.

Therefore, the amount of heat must be increased accordingly, and therefore, the amount of fuel supplied to the boiler (boiler without boiler circulation pump) 21 needs to be increased. However, since the steam temperature and the gas temperature of the boiler without boiler feed pump 21 are limited, it is not possible to charge the fuel excessively. Further, in order to increase the temperature of water supplied to the boiler 21 without a boiler water supply pump, the pressure of the deaerator 7 can be increased to increase the temperature of the boiler water. There is a problem that needs to be. In FIG. 3, the same reference numerals as those in FIG. 2 indicate substantially the same parts.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and aims to effectively use drain generated in a water separator drain system without increasing cost, so that heating steam to a deaerator is heated. It is an object of the present invention to provide a variable-pressure once-through boiler capable of performing efficient boiler circulation without increasing the amount of boiler.

[0014]

In order to achieve the above object, a variable-pressure once-through boiler according to the present invention comprises a steam generation system from a deaerator to an evaporator via a boiler feed pump and a steam generation system. A variable-pressure once-through boiler provided with a connected water separator drain system is characterized in that the water separator drain system is connected to the deaerator.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating an evaporation generation system and a water separator drain system of a variable-pressure once-through boiler as one embodiment of the present invention. As shown in FIG. 1, the variable-pressure once-through boiler 22 ( Hereinafter, the boiler 22 is simply referred to as a “boiler 22”. A steam generation system 30 from the deaerator 7 to the evaporator 5 through the boiler feed pump 11 and the economizer 4 and a water generation system 30 It is provided with a water separator drain system 31 having a water separator drain tank 2 and a condenser 6 connected through a separator 1. Reference numeral 8 denotes a heating steam supply path, and reference numeral 9 denotes a boiler water supply path.

Here, the deaerator 7 removes dissolved gas from the feed water heated by the heating steam supplied from the heating steam supply passage 8, and has a feed water deaerator 7A and a water storage tank 7B. I have. The feedwater deaerator 7A heats water (feedwater) supplied from the outside by heating steam supplied from a steam turbine (not shown) through a heating steam supply path 8,
Dissolved gas is removed from the heated feed water, and the water storage tank 7B stores the feed water from the feed water deaerator 7A.

A boiler feed pump (BFP) 11
Is to pressurize the feedwater from which the dissolved gas has been removed in the deaerator 7, and the feedwater pressurized in the boiler feed pump 11 is sent to the subsequent economizer 4 as boiler feedwater (high-pressure water). Has become. Furthermore, the economizer 4 raises the temperature of the boiler feed water from the boiler feed pump 11 and uses the residual heat of the flue gas to preheat the feed water before entering the evaporator 5.

The evaporator 5 converts the boiler feed water preheated in the economizer 4 into steam, and the steam is supplied to a superheater (not shown) via a water separator 1 described later.
To be sent to As described above, a portion from the deaerator 7 to the evaporator 5 via the boiler feed pump 11 and the economizer 4 is configured as a steam generation system 30.

Further, a water separator (WS) 1
Is for separating a mixture of steam and water from the evaporator 5 and, as described above, sends the steam from the evaporator 5 to the superheater while water (water separator drain; water that has not become steam). To the subsequent water separator drain tank 2
To return to In addition, the above-mentioned superheater superheats the steam from the evaporator 5 to the saturation temperature or more.
The superheated steam is sent to a turbine (not shown).

The water separator drain tank (WS drain tank) 2 stores the water separator drain (hereinafter, may be simply referred to as “drain”) separated by the water separator 1, and is connected via a connection pipe 10. And connected to the deaerator 7. Thereby, the drain from the water separator drain tank 2 can be sent to the deaerator 7 through the connection pipe 10.

That is, in the present embodiment, the temperature of the supply water stored in the water storage tank 7B of the deaerator 7 is increased by sending the high-temperature drain from the water separator drain tank 2 to the deaerator 7. Is available. That is, since the heat of the drain can be recovered in the deaerator 7, the boiler feedwater temperature can be increased without requiring a large amount of heated steam for increasing the pressure of the deaerator 7.

As described above, by circulating the water used in the boiler 22, high-temperature boiler feedwater can be sent to the economizer 4, and as a result, the steam generated by the evaporator 5 The amount can be increased. Further, the water separator drain tank 2 is provided with a detecting device (not shown) for detecting the amount of drain sent, and the detecting device detects the amount of drain sent from the water separator 1. When a decrease (or zero) is detected, a valve (not shown) of a pipe connected to the deaerator 7 is closed.

That is, in the boiler 22, since the amount of boiler feedwater evaporated from the evaporator 5 is small in a wet operation region (a large amount of drain) with a low load from the start thereof, the boiler is separated in the water separator 1. In the water separator drain tank 2, a valve is opened to send high-temperature drain to the deaerator 7.

Thereafter, when the boiler load rises and the evaporation amount of the boiler feed water in the evaporator 5 increases (when the operation range becomes high load), the amount of drain separated in the water separator 1 decreases. In the separator drain tank 2, the valve is closed. As described above, the water separator 1 and the water separator drain tank 2 are connected to the water separator drain system 31 connected to the steam generation system 30.
Is configured as

The condenser 6 mainly cools the steam after finishing the work in the turbine and returns the steam to water, and the steam and the like sent from other parts (for example, as shown in FIG. 1) , The drain from the water separator drain tank 2 is received and returned to water. Specifically, the condenser 6 cools (performs heat exchange) using seawater, and the water returned in this manner is used as water supply to the deaerator 7. It is. That is, the water returned in the condenser 6 is also sent to the deaerator 7, and the boiler 22 operates by circulating the used water.

With the above-described configuration, when the water heated by the heating steam is supplied to the variable-pressure once-through boiler 22 of the present invention, as shown in FIG. And stored in the water storage tank 7B. Then, the water supply stored in the water storage tank 7B is
After being pressurized by the boiler feed pump 11, the water is sent to the economizer 4 as boiler feed water, and the water temperature is raised. And the boiler feed water whose temperature has been raised in the economizer 4 is
It is converted into steam in the evaporator 5 and sent to the superheater via the water separator 1.

On the other hand, the water (drain) which has not been converted into steam in the evaporator 5 is returned to the water separator drain tank 2 via the water separator 1, and is transferred from the water separator drain tank 2 to the water storage tank 7 B of the deaerator 7. Sent. At this time, the water supply from the condenser 6 is supplied to the water supply deaerator 7A of the deaerator 7. And the water storage tank 7B
In, the drain from the water separator drain tank 2 and the feed water are mixed, and the water from the water storage tank 7B is turned into steam again through the boiler feed pump 11, the economizer 4 and the evaporator 5, and the water that is not turned into steam is removed again. The boiler feedwater is sent to the gasifier 7 and the circulation of the boiler feedwater is repeated.

When the boiler load increases and the amount of steam supplied to the boiler in the evaporator 5 increases (the amount of drain decreases), a valve (shown in the figure) to the deaerator 7 of the water separator drain tank 2 Abbreviation) is closed. As described above, according to the variable-pressure once-through boiler as one embodiment of the present invention, the water separator drain can be mixed with the water supply to the deaerator 7 in a low-load wet operation range from the start of the variable-pressure once-through boiler. Thus, efficient boiler circulation can be performed without increasing the amount of heated steam to the deaerator 7, and this can greatly contribute to improving the performance of the present apparatus.

Further, according to the present invention, the valve can be opened and closed in the water separator drain tank 2 in accordance with the amount of drain generated. The drain can be sent, and the boiler can be operated efficiently.

[0030]

As described above in detail, according to the variable-pressure once-through boiler of the present invention, the water separator drain can be mixed with the water supply to the deaerator, so that the amount of steam heated to the deaerator is increased. Without this, efficient boiler circulation can be performed, which can greatly contribute to improving the performance of the present apparatus.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a steam generation system and a water separator drain system of a variable-pressure once-through boiler according to one embodiment of the present invention.

FIG. 2 is a diagram for explaining a steam generation system and a water separator drain system of a general variable-pressure once-through boiler.

FIG. 3 is a diagram for explaining a steam generation system and a water separator drain system of a general variable-pressure once-through boiler.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Water separator (WS) 2 Water separator drain tank (WS drain tank) 3 Boiler circulation pump (BCP) 4 Energy saving device 5 Evaporator 6 Condenser 7 Deaerator 7A Feed water deaerator 7B Water tank 8 Heating steam supply Road 9 Boiler water supply line 10 Connection piping 11 Boiler water supply pump (BFP) 20, 21, 22 Variable-pressure once-through boiler 30 Steam generation system 31 Water separator drain system

Claims (1)

[Claims] 1. A variable-pressure once-through boiler comprising a steam generation system from a deaerator to an evaporator via a boiler feed pump, and a water separator drain system connected to the steam generation system. A once-through boiler, characterized in that a system is connected to the deaerator.