JP2955085B2 - Transformer once-through boiler - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the control of a once-through boiler having a flue evaporator.

[0002]

2. Description of the Related Art FIG. 2 is a system diagram showing an example of a conventional variable-pressure once-through boiler. In the figure, 1 is a economizer, 2 is a furnace water cooling wall, 3
Denotes a flue evaporator, 4 denotes a water separator, 5 denotes a primary superheater, 6 denotes a secondary superheater, 7 denotes a spray system, 10 denotes a flow regulating valve, and 12 denotes a spray. As shown in this figure, conventionally, the entire fluid flow rate except the spray water flow rate has passed through the flue evaporator 3.

[0003]

In a once-through boiler, a once-through operation is carried out at a normal load. However, at a low load, the furnace wall tube is disposed at a higher rate than the main steam flow in order to protect the furnace wall tube in the combustion zone. As shown in FIG. 2, the flow rate of the flow is increased, and the flow rate is recovered as saturated water (drain) by the water separator 4, and heat recovery is performed to remove the flow outside the system (deaerator / recovery). Water tank).

[0004] That is, under a load in which the flow-through operation is performed, the entire amount of steam passes through the water separator, and no drain is generated. However, when a rapid load change (load increase) operation is performed, drainage may be generated in the water separator due to a difference in heat capacity between the heat transfer tubes and the like even when the once-through operation is performed. At this time, in the once-through operation, this phenomenon affects the control of the entire boiler.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned conventional problems, the present invention is directed to a furnace water cooling wall from a downstream side.
In sequence, at least a flue evaporator and water separator
Spraying downstream from the water separator
In a variable- pressure once- through boiler having a spray system, a pipe with a flow control valve that branches off from the inlet of the flue evaporator and joins the spray system is controlled so that it can be used when the load changes.
The present invention proposes a variable-pressure once-through boiler having a water separator bypass system .

[0006]

In the present invention, the water separator bypass system is controlled in advance so as to be utilized when the load changes, so that the water separator is not drained when the load changes, so that disturbance is not given to the boiler control. Then, the boiler can be controlled without being affected by disturbance, and the control system can be stabilized.

[0007]

FIG. 1 is a system diagram showing an embodiment of the present invention. In the figure, 1 is a economizer, 2 is a furnace water cooling wall, 3 is a flue evaporator, 4 is a water separator, 5 is a primary superheater, 6 is a secondary superheater, 7 is a spray system, and 8 is a flue evaporator. A bypass system, 9 and 10 are flow regulating valves, 11 is a check valve, and 12 is a spray.

In this embodiment, a system 8 that bypasses the flue evaporator 3, the water separator 4, and the primary superheater 5 is provided. The bypass system 8 is controlled by operating the flow regulating valve 9 to reduce the flow rate of the fluid passing through the flue evaporator 3, the water separator 4, and the primary superheater 5 when the load changes. As a result, the outlet enthalpy of the flue evaporator 3 is raised, and generation of drain in the water separator 4 is prevented. Thus, the boiler control can be stabilized.

More specifically, in this embodiment, a system 8 is provided to bypass the flue evaporator 3 so that the fluid flowing into the water separator 4 is always superheated even when the load changes. It is. The bypass system 8 is supplied together with spray water to a spray 12 installed on the outlet side of the primary superheater 5, and controls the degree of superheat of the water separator inlet steam when the load changes. At this time,
Since the bypass system 8 branches off after passing through the furnace wall 2 and bypasses, the water flowing through the furnace wall 2 is not reduced, that is, without increasing the outlet fluid temperature (enthalpy) of the furnace wall 2. The inlet steam temperature of the separator 4 can be controlled.

In this embodiment, only the flue evaporator is bypassed. Alternatively, a bypass including a rear flue water cooling wall may be bypassed. In the case of a boiler having two or more sprays, if this system is applied to only one of the sprays, a spray for controlling the degree of superheat of the steam at the inlet of the water separator in an emergency such as a load change,
Since the spray for controlling the steam temperature at the boiler outlet is separate and controlled separately, the control can be performed more easily.

[0011]

According to the present invention, the present invention can be utilized when the load changes.
Water separator bypass system controlled
So are, even when the rapid load changes, the flow regulation
By operating the valve, the water separator bypass
Control the system, and when the load changes, the flue evaporator
Reduce the flow rate of fluid passing through a parator, etc.
Rise the outlet enthalpy of the
The incoming fluid can always be superheated steam.
To prevent drainage on the water separator
Therefore, it is possible to eliminate factors that cause disturbance in the steam temperature control.

[Brief description of the drawings]

FIG. 1 is a system diagram showing one embodiment of the present invention.

FIG. 2 is a system diagram showing an example of a conventional variable-pressure once-through boiler.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Energy-saving device 2 Furnace water cooling wall 3 Flue evaporator 4 Water separator 5 Primary superheater 6 Secondary superheater 7 Spray system 8 Flue evaporator bypass system 9 Flow control valve of 8 10 Flow control valve of 7 11 Check Valve 12 spray

Claims (1)

(57) [Claims] (1) From the furnace water cooling wall to the downstream side,
At least a flue evaporator and water separator
Spray that sprays downstream from the water separator
In a variable- pressure once- through boiler having a system, a line with a flow control valve that branches off from the inlet of the flue evaporator and joins the spray system is controlled so as to be utilized when the load changes.
A once- through boiler comprising a water separator bypass system .