JPH0623723Y2 - Combustor injection steam drain treatment device - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial field of application) The present invention relates to a combined cycle power plant including a gas turbine and a steam turbine, and in particular, injection steam to a combustor of the gas turbine. The present invention relates to a combustor-injected steam drain treatment device that discharges drain at appropriate timing.

(Prior Art) In recent years, combined cycle power plants have come to be widely used.

This plant sends the exhaust gas from the gas turbine to an exhaust heat recovery heat exchanger to generate steam, and drives the steam turbine with this steam to combine the power obtained by the steam turbine with the power generated by the gas turbine. It aims to achieve even more efficient equipment operation and contributes to energy saving by utilizing the heat retained in the exhaust gas of the gas turbine, and also has the advantage that the time required for starting and stopping is relatively short. Has been widely adopted.

FIG. 3 shows a main part of a conventional combined cycle power generation, which is a gas turbine system including a compressor 1, a combustor 2 and a gas turbine 3, a steam turbine 4 and a condenser 5. A turbine system and an exhaust heat recovery heat exchanger 6 provided at a position connecting both systems are provided. Reference numeral 7 in the figure indicates a generator.

In the above configuration, the high pressure air from the compressor 1
Sent to where the fuel is added. The combustion gases are sent to the gas turbine 3, where the thermal energy is converted into power. The exhaust gas leaving the gas turbine 3 is sent to the exhaust heat recovery heat exchanger 6 to heat the feed water. The generated steam is sent to the steam turbine 4, and the heat energy is converted into power again. The generator 7 is turned by both the gas turbine 3 and the steam turbine 4 and produces an electrical output. Exhaust gas from the steam turbine 4 is collected by the condenser 5 as condensed water.

Further, steam is injected into the combustor 2 in order to reduce nitrogen oxides (hereinafter referred to as NO _x ) in the exhaust gas from the gas turbine 3. This injection steam system is shown in FIG. The injection steam system has two steam sources. That is, the extracted air from the steam turbine 4 is sent to the temperature reducer 10 through the extraction pipe 8 and the check valve 9. On the other hand, from the high temperature steam pipe 12 connected to the main steam pipe 11, steam is sent to the desuperheater 10 via the pressure control valve 13 when the steam pressure in the extraction pipe 8 is lower than the set pressure. The steam sent to the desuperheater 10 is mixed with cooling water by a water injection valve 14 that controls the temperature to a preset temperature. The steam whose temperature has dropped is injected into the combustor 2 through the injection steam pipe 15, the flow transmitter 16, the stop valve 17, and the flow control valve 18. Further, a drain pipe 19 is connected to the injection steam pipe 15 in front of the flow rate transmitter 16, and the steam drain is discharged to the drain pit 20a via the drain trap 20.

(Problems to be Solved by the Invention) In the above-described conventional method, the drainage of steam generated in the injection steam pipe 15 is captured by the drain trap 20. In general,
The desuperheater 10 must have a long straight pipe line in order to successfully mix the steam and the cooling water, but in the power plant, the required layout cannot be obtained, so a large amount is generated when the load changes. It is conceivable that the drain or the trap 20 will not be able to completely process it, and that a part of it will flow to the combustor 2 together with the injected steam. If a large amount of drain flows into the combustor 2, thermal contraction of the metal part will increase,
Excessive stress may damage the combustor 2.

Therefore, an object of the present invention is to provide an injection steam drain treatment device capable of promptly treating a large amount of drain generated when a plant load changes and thereby preventing the drain from flowing into a combustor together with the injection steam. is there.

[Constitution of device]

(Means for Solving the Problems) The present invention has a drain pipe having a drain trap that is branched from an injection steam pipe that guides injection steam to a combustor and has the other end connected to a drain pit to achieve the above object. This drain pipe has a drain trap and a drain valve installed in parallel.When the injected steam flowing to the combustor is condensed in large quantities due to fluctuations in the operating conditions of the plant, the drain valve is opened to discharge the drain out of the system. It is characterized by doing so.

(Function) The present invention opens the drain valve when the temperature control delay is large and the load change rate is large, the steam flow rate is reduced, and the superheat degree of the steam is reduced as a condition in which drainage is likely to occur. To

This allows the drain generated in the injection steam pipe to be promptly discharged to the outside of the system.

(Embodiment) An embodiment of the present invention will be described with reference to FIGS. 1 and 2.

In the configuration of FIG. 1, the same components as those shown in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 1, the drain pipe 19 is provided with a drain valve 21 in parallel with the drain trap 20. The drain valve 21 is a two-position operation type valve, and is opened / closed by a control signal output from the drain valve control device 22. The load signal a, the injection steam flow rate signal b output from the flow rate transmitter 16 and the injection steam pressure signal c output from the pressure transmitter 23 are input to the drain valve control device 22, and the following calculation is executed. It
FIG. 2 shows a calculation function in the drain valve control device 22. The load signal a is input to the differentiator 24, where the rate of change is calculated. The load change rate signal d is output to the comparator 25 and a deviation is obtained from the change rate target signal output from the signal generator 26, and the opening command signal e for determining the valve position based on the deviation is the OR circuit 27. Is output to.

Further, the injection steam flow rate signal b from the flow rate transmitter 16 is a comparator.
A deviation is calculated with respect to the flow rate target signal output from the signal transmitter 29, and the opening command signal f for determining the valve position based on the deviation is output to the OR circuit 27.

Further, the injection pressure signal c output from the pressure transmitter 22 is input to the calculator 30 where the saturation temperature corresponding to the pressure is calculated. The saturation temperature signal g is output to the comparator 31 to obtain a deviation from the saturation temperature target signal given from the signal transmitter 32, and is output to the OR circuit 27 as an opening degree instruction signal h for determining the valve position based on the deviation. To be done. In the OR circuit 27, when any one of the opening command signals e, f, h is input, the drain valve 21 is placed in the fully open position, while if these signals e, f, g are not given, An opening degree instruction signal i for placing in the fully closed position is output. Incidentally, reference numeral 28 in the drawing indicates a knot circuit.

The configuration of the above embodiment operates as follows. When the load change rate is large, the opening instruction signal e is output from the comparator 25 based on the load signal a, and the drain valve 22 is opened via the OR circuit 27. When the amount of injected steam is small, the comparator 28 outputs the opening degree instruction signal f based on the injected steam flow rate signal b, and the drain valve 22 is fully opened via the OR circuit 27. Further, when the saturated temperature of the injected steam is close to the saturated temperature, the opening command signal h is output from the comparator 31 based on the injected steam pressure signal c, and the drain valve 22 is opened via the OR circuit 27. As a result, under each of the above conditions, the drain valve 22 is opened to allow a large amount of drain to be discharged, and the drain is prevented from flowing into the combustor 2.

On the other hand, when the rate of change in load is small, the amount of injected steam is large, and the saturation temperature of the injected steam is lower than the saturation temperature, none of the opening instruction signals e, f, h are issued, so the drain valve 22 is The drain is not opened, and therefore, the drain is discharged within the capacity of the drain trap 20 at this time.

[Effect of device]

As described above, according to the present invention, the drain valve is installed in parallel with the drain trap, and when the drain is likely to occur, that is, when the temperature control delay is significant and the load change rate is large, the steam flow rate decreases and the steam flow velocity decreases. When the temperature reduction effect decreases, the degree of superheat of the vapor fluid decreases as the steam pressure fluctuates, and the drain valve is opened when it reaches the drain generation area. It can be discharged through the drain pipe, and it is possible to prevent the drain from entering the combustor.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a combustor injection steam drain treatment device according to the present invention, FIG. 2 is a functional block diagram of a drain valve control device according to the present invention, and FIG. 3 is a conventional combined cycle power plant. FIG. 4 is a system diagram showing a conventional combustor injection steam system. 2 ... Combustor, 8 ... Bleed pipe 15 ... Injection steam pipe, 16 ... Flow transmitter 19 ... Drain pipe, 20 ... Drain trap 21, Drain valve, 22 ... Drain valve control device 23 ... Pressure transmitter, 24 ... Differentiator 25, 28, 31 ... Comparator, 30 ... Calculator

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shoji Matsui 66-2 Horikawa-cho, Sachi-ku, Kawasaki-shi, Kanagawa Toshiba Engineering Co., Ltd. (56) Reference JP-A-63-134819 (JP, A) JP Sho 63-205424 (JP, A) Actually opened Sho 63-150039 (JP, U)

Claims (2)

[Scope of utility model registration request] 1. A drain pipe having a drain trap branched from an injection steam pipe for introducing the injection steam to a combustor and having the other end connected to a drain pit, and a drain valve provided in parallel with the drain trap of the drain pipe. Combustor injection, characterized in that, when the injection steam flowing into the combustor is condensed in a large amount due to fluctuations in operating conditions of the plant, the drain valve is opened to discharge the drain out of the system. Steam drain treatment device. 2. A drain valve determines deviations from respective target values based on a plant load signal, an injection steam flow rate signal, and an injection steam pressure signal, and opens when any one deviation is large. The combustor-injected steam drain treatment device according to claim 1, further comprising a drain valve control device having a control circuit.