JPS59221503A - Reheater for turbine power device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a steam turbine power plant that reheats cycle steam at low pressure by using a part of steam supplied to a steam turbine power generation cycle. In particular, the present invention relates to means for reducing thermal stress within the reheater during startup.

[Background of the invention]

In steam turbine power plants that operate on a substantially saturated supply of steam, such as power plants supplied with steam by boiling water or pressurized water nuclear reactors, moisture is typically removed from the steam by using a moisture separator reheater. and may be placed in a pressure vessel separate from the high-pressure turbine; typically a portion of the steam input to the steam turbine is removed from the high-pressure turbine.
As a fluid for heating low-temperature cycle steam, it is introduced into a reheater with an additional reheating function.

In the reheat stage, which has the highest temperature in the reheater, part of the steam from the steam source that supplies the high-pressure turbine is used as the heating fluid for reheating, so the temperature on the "tube side" of the reheater tube bundle increases with the load. It never changes. On the other hand, the temperature through which the cycle steam to be reheated varies over a wide range with load, as the cycle steam is performing work in the high pressure turbine.

Therefore, at startup and under partial load, a considerable temperature difference occurs between the outer shell side and the tube side, and thermal stress is generated at various parts within the reheater due to the temperature difference.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a reheater for a turbine power unit that reduces thermal stress within the reheater caused by a temperature difference in the valley of the reheater when a steam turbine is started.

[Summary of the invention]

The key point of the present invention is to preheat the entire reheater to the same heating temperature before starting the steam turbine to minimize the generation of thermal stress within the reheater that occurs during startup.

[Embodiments of the invention]

Embodiments of the invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, the steam turbine power plant includes a high-pressure turbine section 1, a low-pressure turbine section 2, and a moisture separation reheater 4 that serves as a steam separator and a reheater.

In practice, several moisture separator reheaters are used, but only one is shown for clarity of illustration. Main steam line 5
The incoming steam expands and becomes more humid while passing through the high pressure turbine 1. This high-humidity cycle steam flows through a 6-ft line into the moisture separator reheater 4 through a plurality of inlets at the bottom of the pressure shell of the moisture separator reheater 4, and enters the moisture separator reheater 4 through a plurality of inlets at the top of the pressure shell. After flowing out from the outlet, it flows into the low pressure turbine 2 through line 9 and is further led to condenser 3 through line 10.

The moisture separator reheater 4 has a plurality of moisture separation elements (not shown) for removing moisture from the cycle steam, and the moisture separation reheater 4 has a plurality of moisture separation elements (not shown) for removing moisture from the cycle steam. and the main steam line 5.
A second stage reheater (not shown) is provided for reheating the cycle steam with steam introduced from the steam line to the branch line 7. Here, the second
The steam flowing from the reheater line 11 flows into the main steam line 5.
Therefore, the steam temperature is approximately constant regardless of the operating conditions of the turbine. On the other hand, since the raw steam and cycle steam guided to the first reheater perform work in the high-pressure turbine 1, the steam temperature changes together with the operating conditions of the turbine.

According to the present invention, lines 11 and 12 branched from the main steam line 5 and a line 13 connecting the outlet of the moisture separation reheater 4 and the condenser are separately provided in addition to the turbine normal operation line. , the moisture separator reheater 4 can be warmed up with main steam line steam, which is the highest steam temperature in the turbine system, prior to starting the turbine.

High pressure turbine 1, moisture separation reheater 4, low pressure turbine 2,
In the line connecting the ascites device 3, gate valves 15, 16, 17, 18, 20, 22 are installed in each line to separate the normal operation line and the moisture separation reheater warm-up line.
．． 24 will be provided. First, before warming up the moisture separator reheater 4, after closing each gate valve, the warm-up lines 11, 12, 13 of the moisture separator reheater and the line 7 leading to the second stage reheater are opened.
Open the gate valves 15, 20, 22, and 24. Thereafter, the main steam is gradually transferred to the moisture separator reheater 4 through the warm-up lines 11, 12, 13 of the moisture separator reheater and the flow control valves 19, 21° 23 of the second stage reheater line 7. Line steam is introduced to preheat the moisture separator reheater.

When steam is introduced, the pressure is reduced by the pressure reducing valve 25 in the line 13 and then the steam is introduced into the condenser 3. After preheating and before normal turbine operation,
The gate valves of warm-up lines 7.11, 12, and 13 are closed and the turbine enters normal operation. Here, the second stage reheater line 7 is shared during normal operation and during warm-up. In addition, the warm-up operation is performed using existing operating techniques such as warming up the high-pressure turbine section, and there are no particular operational problems. In addition, 14 in the figure is a gate valve.

FIG. 2 shows the temperature of each part when steam initially flows into the moisture separation reheater 4.

That is, regarding the second stage reheater temperature 101, second stage reheater temperature 102, cycle steam temperature 103, and moisture separation reheater shell temperatures 104 and 105, the horizontal axis represents time and the vertical axis represents temperature. Shown. The temperature of the outer shell when the warm-up of the present invention is not performed is shown by a line 104, which is the temperature difference from the second stage reheater temperature 101, which is the maximum temperature part in the moisture separation reheater 4. Excessive thermal stress occurs at ΔTl. On the other hand, if the warm-up shown in the present invention is used, the outer shell temperature becomes as shown by the line 105, the temperature difference from the second stage reheater temperature 101 becomes ΔT2, and the thermal stress is reduced.

〔Effect of the invention〕

According to this research, it is possible to avoid excessive thermal stress generated in the moisture separator reheater when starting the turbine, and it is possible to start the turbine quickly and safely.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of a steam turbine power plant according to an embodiment of the present invention, and Fig. g2 is a graph showing temperatures and times at various parts in a moisture separation reheater.

Claims (1)

[Claims] 1. In a reheater for a turbine power unit that reheats cycle steam from a high-pressure turbine using steam from a steam source located within a tube bundle, a cycle steam inflow portion and a heating steam inflow portion of the reheater; A gate valve and a flow rate control valve are installed in the bypass line of the high-pressure turbine that connects the steam source, a low-pressure bin bypass line that connects the cycle steam outlet of the reheater and the water coverer, A reheater for a turbine power unit characterized by comprising a gate valve and a pressure reducing valve provided in a bypass line connecting a cycle steam outlet and a condenser.