JPH04313601A - Boiler equipment - Google Patents

Abstract

PURPOSE:To equalize the exhaust gas from a gas turbine in amount to the exhaust gas from a boiler which is sent to a feedwater heater. CONSTITUTION:A boiler 3 is designed to be fed with the exhaust gas from a gas turbine 1 and with air from a pressurized-draft blower 4; on the outlet side of the boiler 3 there are provided a feedwater heater 5 and an air heater 6 in parallel, the former heater 5 for heating the feedwater to the boiler 3 and the latter heater 6 for heating the air fed to the boiler 3 from the pressurized-draft blower 4; and with a damper 8 provided between the boiler 3 and the air heater 6, by adjusting the damper opening the air from the pressurized-draft blower 4 is designed to be made equal in amount to the exhaust gas from the boiler which is sent to the air heater 6. This arrangement enables equalizing the exhaust gas from the boiler 3, which is sent to the feedwater heater 5, in amount to the exhaust gas from the gas turbine 1, which is sent to the boiler 3.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to boiler equipment.

0002

[Prior Art] In recent years, a gas turbine is used to drive a generator, and unburned oxygen in the turbine exhaust gas from the gas turbine is used to burn fuel in a boiler, and the steam generated by the boiler is used to drive the generator. 2. Description of the Related Art A so-called exhaust reburning combined cycle boiler equipment has been put into practical use, which heats feed water supplied to a boiler using boiler exhaust gas. According to the boiler equipment, the thermal efficiency of the equipment can be improved by recovering heat from a large amount of boiler exhaust gas to the water supply.

[0003] The flow mainly in the gas system of the boiler equipment is shown in FIG. It is a boiler that burns fuel using oxygen or the unburned oxygen and air supplied by the strong pressure ventilator 4, and heats and evaporates the supplied water to generate steam. Air can be fed to the boiler 3 when the amount of oxygen is insufficient from the turbine exhaust gas from the gas turbine 1 alone under high load.

5 is a feed water heater that heats the feed water to be fed to the boiler 3 using the boiler exhaust gas discharged from the boiler 3;
6 is an air heater that is arranged in parallel with the feed water heater 5 and heats the air sent from the strong pressure draft fan 4 and supplied to the boiler 3 using boiler exhaust gas from the boiler 3; 7 is a feed water heater A damper 5 is provided on the inlet side of the air heater 6, and a damper 8 is provided on the gas inlet side of the air heater 6.

In the boiler equipment described above, when the boiler load is low, the combustion gas in the boiler 3 is unburned oxygen in the turbine exhaust gas discharged from the gas turbine 1 after driving the generator 2, and strong pressure ventilation is used. The machine 4 is either stopped or rotating at the minimum rotation speed. Therefore, the damper 7 opens,
The damper 8 is closed or slightly opened, and most of the boiler exhaust gas is sent to the feed water heater 5, where the feed water supplied to the boiler 3 is heated.

[0006] Also, the steam generated by heating in the boiler 3 is sent to a steam turbine (not shown), which drives a generator, and condenses into water in a condenser, which heats the feed water. It is heated in the vessel 5 and supplied to the boiler 3.

[0007] When the boiler load is high, the combustion gas in the boiler 3 is insufficient due to the unburned oxygen in the turbine exhaust gas.

Therefore, the gas turbine 1 is operated at maximum load, and the air volume of the strong pressure fan 4 increases in response to the boiler load. Air sent from the boiler 4 and heated by the air heater 6 is sent to the boiler 3 and used for fuel combustion, and a part of the boiler exhaust gas discharged from the boiler 3 is sent to the feed water heater 5, and the remaining part is sent to the feed water heater 5. The exhaust gas is sent to the air heater 6, and the feed water and air supplied to the boiler 3 are heated.

[0009] When the boiler load is between a low load and a high load, both the gas turbine 1 and the strong pressure fan 4 are operated at a load and air volume corresponding to the boiler load, and the turbine exhaust gas corresponding to the boiler load is and air is fed to the boiler 3.

0010

[Problems to be Solved by the Invention] In the boiler equipment described above, in order to increase heat recovery efficiency, the gas turbine load, that is, the amount of turbine exhaust gas sent from the gas turbine 1 to the boiler 3 is equal to the amount of gas sent to the feedwater heater 5. It is desirable to operate so that they are approximately equal.

[0011] Thus, when the boiler is under low load, only the gas turbine exhaust gas is used as combustion gas for the boiler 3,
Since almost all of the boiler exhaust gas passes through the feedwater heater 5, the amount of turbine exhaust gas supplied to the boiler 3 is equal to the amount of gas sent to the feedwater heater 5, which poses no particular problem in terms of boiler equipment operation. At an intermediate load between a high load and a high load, air from the strong pressure fan 4 is supplied to the boiler 3 as combustion gas in addition to the turbine exhaust gas.
It is necessary to control the opening degrees of the dampers 7 and 8 so that the amount of turbine exhaust gas sent to the boiler exhaust gas and the amount of boiler exhaust gas sent to the feedwater heater 5 are equal, and various means are considered as means for this control. However, the reality is that no simple and reliable means have yet been proposed.

The present invention has been made in view of the above-mentioned circumstances, with the object of making it possible to adjust the amount of boiler exhaust gas sent to the feed water heater 5 in accordance with the gas turbine load (turbine exhaust gas amount). .

[0013]

[Means for Solving the Problems] The present invention uses turbine exhaust gas from a gas turbine as combustion gas when the boiler load is low, and uses turbine exhaust gas from the gas turbine when the boiler load is high. and a boiler that uses air from the ventilator as combustion gas; a feedwater heater that heats the feed water to the boiler using the boiler exhaust gas from the boiler; an air heater that heats the air to be fed with boiler exhaust gas; a damper that is installed between the boiler and the air heater and adjusts the amount of boiler exhaust gas that is sent to the air heater;
an air amount detector that detects the amount of air fed to the boiler by the ventilator; A control device is provided to control the opening degree of the damper.

[0014]

[Operation] When the boiler load is low, the damper is almost fully closed, and the turbine exhaust gas from the gas turbine is used as combustion gas for the boiler, and all of the boiler exhaust gas is sent to the feed water heater. Heating of the feed water takes place.

[0015] When the boiler load is high or between low and high loads, the turbine exhaust gas from the gas turbine and the air from the ventilator are used as combustion gas for the boiler and are discharged from the boiler. Part of the boiler exhaust gas is sent to the feed water heater to heat the feed water, and the remaining boiler exhaust gas is sent to the air heater to heat the air that is sent to the boiler as combustion gas. Heating takes place. At this time, the amount of air is detected by the air amount detector, and the opening degree of the damper is controlled so that the amount of air and the amount of boiler exhaust gas sent to the air heater are approximately equal, so the amount of air is sent to the feed water heater. The amount of boiler exhaust gas generated is approximately equal to the amount of turbine exhaust gas from the turbine.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the present invention.

In this embodiment, the basic configuration of the boiler equipment is approximately the same as that shown in FIG. 5, and in the figure, the same components as shown in FIG. There is.

In the figure, reference numeral 9 indicates a connection from the strong pressure fan 4 to the air heater 6.
a strong pressure fan air amount detector installed in the system path 10 leading to;
11 is a control device that outputs a damper opening command VD to adjust the opening degree of the damper 8 based on the strong pressure ventilator air amount QA detected by the strong pressure ventilator air amount detector 9; is the strong pressure ventilation air amount QA (
The relationship between the damper 8 (Kg/hr) and the opening degree X (%) of the damper 8 is input.

During boiler operation, a boiler load command is given to the gas turbine 1, the strong pressure fan 4, and the damper 7. As a result, the gas turbine 1 and the strong pressure fan 4 are operated with a predetermined load, and the damper 7 is given the boiler load command. It opens to the opening degree that corresponds to the command. Further, the strong pressure ventilator air amount QA detected by the strong pressure ventilator air amount detector 9 is given to the control device 11.

[0021] When the boiler load is low, the high-pressure fan 4 is stopped or rotated at the minimum rotational speed according to the boiler load command. Therefore, the strong pressure ventilator air amount QA detected by the strong pressure ventilator air amount detector 9 is zero or very small, and the damper 8 is closed or almost closed by the opening command VD from the control device 11. is in a state.

Therefore, only the turbine exhaust gas from the gas turbine 1 is fed to the boiler 3 as combustion gas, and the amount of air fed to the boiler 3 by the strong pressure fan 4 is zero or very small. be.

Further, the boiler exhaust gas discharged from the boiler 3 passes through the damper 7 which is opened to a predetermined opening degree, and the entire amount or substantially the entire amount is sent to the feed water heater 5, where it exits from the feed water heater 5 and is sent to the rear. . Therefore, when the boiler 3 is under low load, the turbine exhaust gas from the gas turbine 1 is sent to the feedwater heater 5 as boiler exhaust gas from the boiler 3, and the amount of turbine exhaust gas and the boiler exhaust gas sent to the feedwater heater 5 are The amounts are approximately equal.

When the boiler load is high, the gas turbine 1 is operated at the maximum load according to the boiler load command, the damper 7 is opened to the maximum opening degree, and the high-pressure fan 4 is driven at a rotation speed corresponding to the boiler load. be done.

The strong pressure ventilator air amount QA detected by the strong pressure ventilator air amount detector 9 is given to the control device 11, and from the control device 11, the damper 8 corresponding to the strong pressure ventilator air amount QA is sent. The opening degree X is given to the damper 8 as the opening degree command VD, and the damper 8 is controlled to a predetermined opening degree X. Therefore, during high load, the maximum amount of turbine exhaust gas is supplied from the gas turbine 1 and the air corresponding to the boiler load is supplied from the strong pressure fan 4 to the boiler 3 as combustion gas.

Also, some of the boiler exhaust gas discharged from the boiler 3 passes through the feed water heater 5 and is then sent to the boiler 3.
The remaining exhaust gas passes through the air heater 6 and heats the air from the high-pressure draft fan 4, which is supplied as combustion gas to the boiler 3. The boiler exhaust gases are combined and sent to the rear.

When the boiler load is an intermediate load between a low load and a high load, the gas turbine 1 and the strong pressure fan 4 are operated at a load corresponding to the boiler load command, and the opening degree X of the damper 8 is the same as in the case of a high load. It is controlled by the strong pressure ventilation air amount QA.

When the boiler load is high or between a low load and a high load, the amount of boiler exhaust gas introduced into the air heater 6 is controlled in accordance with the amount of air in the strong pressure fan 4, so that the water supply is The amount of boiler exhaust gas introduced into the heater 5 is approximately equal to the amount of turbine exhaust gas from the gas turbine 1, and the thermal efficiency of the boiler equipment can be improved.

That is, the boiler exhaust gas amount QB (Kg/hr) at the outlet of the boiler 3 is the turbine exhaust gas amount from the gas turbine 1, the turbine exhaust gas amount QT (Kg/hr), and the strong pressure ventilation air amount from the strong pressure ventilation fan 4. QA (Kg/hr)
, the amount of boiler exhaust gas introduced into the feedwater heater 5 is the amount of boiler exhaust gas introduced into the feedwater heater QW (Kg/hr), and the amount of boiler exhaust gas introduced into the air heater 6 is expressed as QH (Kg/hr).
hr), it is expressed as QB=QT+QA =QW+QH, and since the opening degree X of the damper 8 is controlled so that QA=QH, QT=QW, and the same amount of boiler exhaust gas as the turbine exhaust gas amount flows into the feedwater heater. 5 will be supplied.

FIG. 3 shows another embodiment of the present invention, in which the amount of boiler exhaust gas fed to the air heater 6 is modified depending on the temperature of the boiler exhaust gas.

In the figure, 12 is a gas temperature detector provided on the gas outlet side of the air heater 6, 13 is a gain adjuster that determines the correction gain C based on the gas temperature detected by the gas temperature detector 12, and 14 is a multiplier that multiplies the opening command VD from the control device 11 by a correction gain C to obtain a corrected opening command VDC for the damper 8. In addition to the position shown in FIG. 3, the gas temperature detector 12 can also be provided at the gas outlet side of the feed water heater 5 or at a position where the gas from the feed water heater 5 and the gas from the air heater 6 join.

In this embodiment, the temperature of the gas discharged from the air heater 6 is detected, and as shown in FIG. When the temperature is higher than the predetermined temperature TO, a gain (C>1) larger than 1 is applied, and when the temperature is low, a gain (C<1) smaller than 1 is applied from the gain adjuster 13 to the multiplier 14.
The opening command VD from the control device 11 is multiplied by a gain C to obtain a corrected opening command VDC, and the opening X of the damper 8 is adjusted in accordance with the result. By doing this, the turbine exhaust gas of the gas turbine 1 and the feed water heater 5 are
It is possible to perform control such that the amounts of boiler exhaust gas fed to the boiler exhaust gases are equalized even more accurately.

It should be noted that the present invention is not limited to the above-described embodiments, and it goes without saying that various changes can be made without departing from the gist of the present invention.

[0034]

[Effects of the Invention] According to the boiler equipment of the present invention, the amount of exhaust gas from the turbine and the amount of boiler exhaust gas sent to the feed water heater can be easily and reliably equalized, and as a result, the heat recovery efficiency is improved. Various excellent effects can be achieved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a gas system in an embodiment of boiler equipment of the present invention.

FIG. 2 is a graph showing the relationship between the amount of strong-pressure ventilator air in the boiler equipment of the present invention and the damper opening degree for adjusting the boiler exhaust gas sent to the air heater.

FIG. 3 is a block diagram of a gas system in another embodiment of the boiler equipment of the present invention.

FIG. 4 is a graph showing the relationship between the temperature of the gas discharged from the air heater and the gain in the boiler equipment of the present invention.

FIG. 5 is a block diagram of a gas system in an example of conventional boiler equipment.

[Explanation of symbols]

1 Gas turbine 3 Boiler 4 Strong pressure draft fan (ventilator) 5 Feed water heater 6 Air heater 8 Damper 9 Strong pressure draft fan air amount detector (air amount detector) 1
1 Control device

Claims (1)

[Claims] [Claim 1] When the boiler load is low, turbine exhaust gas from the gas turbine is used as combustion gas,
A boiler that uses turbine exhaust gas from a gas turbine and air from a ventilator as combustion gas when the boiler load is high; a feed water heater that heats water to be fed to the boiler using the boiler exhaust gas from the boiler; An air heater that is installed in parallel with the heater and uses boiler exhaust gas to heat the air that is sent from the ventilator to the boiler, and an air heater that is installed between the boiler and the air heater and the amount of boiler exhaust gas that is sent to the air heater. an air amount detector that detects the amount of air sent to the boiler by the ventilation fan, and an air amount detector that detects the amount of air detected by the air amount detector and boiler exhaust gas that is sent from the boiler to the air heater. A boiler facility characterized in that a control device is provided for controlling the opening degree of the damper so that the amounts are substantially equal.