JPS58176405A - Adjusting device for gland steam temperature - Google Patents

Abstract

PURPOSE:To reduce a gland seal steam temperature and prevent a trouble which takes place as a result of expansion differences in the seal, by providing a feeding tube which runs from a steam adjusting device for a steam turbine to a gland seal part, passing through a condensate in a condenser via a control valve. CONSTITUTION:A steam adjusting device 7 reduces a seal steam pressure. A temperature signal T1 sent from a thermocouple 13 is compared with a target value by a control device 14 which in turn emits signals T2 and T3 indicating any difference. When a temperature T1 detected is higher than a preset value, a control valve 16 is closed and a control valve 17 is opened, thereby increasing a steam quantity to be cooled by a condensate and lowering a steam temperature to be supplyed to a gland. On the contrary, if the temperature detected is lower than a preset value, the control valve 17 is closed and the control valve 16 is opened, thereby elevating a steam temperature to be supplyed to a gland. In this manner, the gland is prevented from causing an excessive expansion difference between the high and low temperatures of seal steam.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a device for adjusting the temperature of seal steam sent to a grand seal portion of a steam turbine.

[Technical background of the invention and its problems]

In conventional steam turbines, gland steam for a steam seal supplied to a low-pressure turbine is guided into a low-pressure turbine exhaust chamber through a gland steam regulator through a gland steam piping during startup and low load.

Figure 1 shows a ground steam system during load operation of a normal steam turbine. The steam turbine consists of a high pressure turbine 1 and a low pressure turbine 2.
When the steam turbine consisting of the low-pressure packing 4 is operating at full load, the ground leak steam from the gland packing 3 of the high-pressure turbine 1 is guided to the gland packing 4 of the low-pressure turbine 2 and becomes low-pressure gland seal steam. During low-load operation, there is little gland leak steam from the gland packing 3 of the high-pressure turbine 1, so the sealing steam supplied to the gland packing 4 of the low-pressure turbine 2 cannot be supplemented, and the insufficient steam is transferred to the main steam line 5 or auxiliary steam. It is supplied from the line 6, passes through the steam regulator 7, and flows into the gland packing 4 of the low pressure turbine 2 as seal steam.

The steam from the main steam line 5 and the auxiliary steam line 6 are both high-temperature steam, and it is inappropriate to supply them as seal steam to the gland packing 4 of the low-pressure turbine 2 simply by reducing the pressure with the gland steam regulator 7. Yes, we need to cool down. In conventional turbines, the required length of the gland piping was determined in consideration of the exhaust temperature distribution and cooling effect in the space between the low-pressure semi-exhaust chamber and the condenser, and the piping was routed. However, this is unreliable and the cooling effect varies depending on the load and is unstable.

When stopping the route of gland piping, it is necessary to install a gland seal steam desuperheater to reduce the temperature, but this has disadvantages such as being expensive and requiring a new installation location and water system. .

[Purpose of the invention]

The purpose of the present invention is to reduce the gland seal steam temperature to a predetermined temperature without the need for conventional piping between the low-pressure turbine exhaust chamber and the condenser or the installation of an expensive gland seal steam desuperheater. An object of the present invention is to provide a gland steam temperature regulating device which can prevent troubles caused by differential expansion.

[Summary of the invention]

In order to achieve the above object, the present invention provides a steam regulator that reduces the pressure of seal steam sent to the grand seal section of a steam turbine, and a supply pipe that directly communicates from the steam regulator to the grand seal section via a first control valve. a supply pipe communicating from the steam regulator to the gland seal through condensate at the lower part of the condenser via a second control valve; a temperature detector for detecting the steam temperature in the gland seal; and a control thereof. Depending on the device, the opening degrees of the first and second control valves are adjusted according to the difference between the temperature detected by this temperature sensor and the temperature set in the control device, and the optimum temperature is adjusted. The feature is that the steam is sent to the gland seal section.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 2 and 3. In these figures, the same parts as in FIG. 1 are given the same reference numerals, and their explanation will be omitted.

FIG. 2 shows a portion of the low pressure turbine in the present invention. The low-pressure turbine consists of a low-pressure exhaust chamber 8.9, a low-pressure rotor 10, and a low-pressure internal casing 11,12. A gland packing is provided at the portion where the low pressure rotor 10 passes through the low pressure exhaust chambers 8 and 9, and a thermocouple 13 for detecting the temperature of the sealing steam is attached to the sealing steam supply section of the gland packing casing. The temperature signal T1 from the thermocouple 13 is compared with a preset temperature target value in the control device 14, and difference signals T and T are generated.

Grand arrangement for clan seal steam supply '1f15
is divided into two parts. One is the supply pipe 19 which is connected to the pipe 18 to the gland seal section 4 via the control valve 16, and the other is the supply pipe 19 which is connected to the pipe 18 after passing through the condensate at the lower part of the condenser via the control valve 17. A supply pipe 20 is connected to the supply pipe 20.

Next, the effect will be explained. The temperature signal T of the gland packing part 4 detected by the thermocouple 13 is sent to the control device 14 and compared with the set temperature To, and control signals T2 + TI based on the difference ΔT are sent to the control valves 16 and 17, respectively. Sent.

When the temperature difference ΔT is large, the control valve 16 is closed based on the signal <Tz times as shown in FIG. 3, and the amount of high-temperature steam is reduced.

At the same time, the control valve 17 is opened by the T signal, the amount of steam cooled by condensate increases, and the temperature of the gland supply steam decreases. On the other hand, if the detected temperature T1 is lower than the set temperature T0, the control valve 17 is further closed and the control valve 16 is further opened in the exact opposite manner to the above.

Acts to raise the gland supply steam temperature.

As described above, according to the present invention, the gland seal steam temperature can be maintained at an appropriate temperature throughout all operating conditions, including during turbine startup, low load, and full load.

〔Effect of the invention〕 According to the present invention, the following effects can be obtained.

1) The difference in excessive elongation caused by high and low seal steam temperatures can be reduced, improving performance.

3) The purpose can be achieved by combining proven conventional equipment without using expensive equipment such as a gland seal steam desuperheater or complicated water system.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a ground steam system of a conventional steam turbine, and FIGS. 2 and 3 are a block diagram and a curve diagram showing an embodiment of the present invention. 3 Gland seal section (high pressure packing) 4... Grand seal section (low pressure packing) 7 Steam regulator 13.
・Temperature detector (thermocouple) 14 Control device 16
．． 17・Control valve 19.20・Supply pipe (7317) Agent Patent attorney Noriyuki Chika (
and 1 other person) (7) Figure 2

Claims (1)

[Claims] a steam regulator that reduces the pressure of seal steam to be sent to the grand seal section of the steam turbine; a supply pipe that directly communicates from the steam regulator to the grand seal section via a first control valve; It consists of a supply pipe that passes through the condensate at the bottom of the condenser and communicates with the gland seal section via a control valve, and a temperature detector that detects the steam temperature in the gland seal section and its control device. The opening degree of the first and second control valves is adjusted according to the difference between the detected temperature and the temperature set in the control device, and steam at the optimum temperature is sent to the gland seal section. Grand steam temperature regulator.