JPH033045B2

JPH033045B2 -

Info

Publication number: JPH033045B2
Application number: JP7084882A
Authority: JP
Inventors: Hiroshi Uchida
Original assignee: Tokyo Shibaura Electric Co Ltd
Current assignee: Toshiba Corp
Priority date: 1982-04-27
Filing date: 1982-04-27
Publication date: 1991-01-17
Also published as: JPS58187505A

Description

[Detailed description of the invention]

〔発明の技術分野〕本発明は、タービン起動時における主蒸気リー
ド管のウオーミング装置に関する。〔発明の技術的背景〕一般に、蒸気タービンにおいては、第１図に示
すように、主蒸気管１から蒸気タービン２に向う
蒸気は、主蒸気止め弁３または主蒸気止め弁バイ
パス弁４を流過した後、複数本（この例ではNo.１
からNo.４までの４ライン）の主蒸気リード管５−
１〜５−４に分流し、夫々蒸気加減弁６−１〜６
−４を経て、蒸気タービン２の各第１段落ノズル
室７−１〜７−４に導入される。各主蒸気リード管５−１〜５−４にはドレン管
８−１〜８−４が接続され、ドレンは各々ドレン
元弁９−１〜９−４およびドレン弁１０−１〜１
０−４を通して排出されるように構成されてい
る。上述の如き蒸気タービンにおいては、起動に先
立つて、主蒸気管１、主蒸気リード管５−１〜５
−４、および蒸気タービン２は蒸気によつてウオ
ーミングされるが、起動前のウオーミングでは多
量の蒸気を流すとタービンが回転を始めるので、
必要最小限の蒸気量で長時間の暖機を行なうよう
にしている。この場合、ウオーミングによる温度上昇は、ウ
オーミング蒸気圧力に相当する飽和温度までしか
期待できない。一方、タービン起動後は、主蒸気温度は急速に
上昇するので、遅れて開弁される蒸気加減弁に連
なる主蒸気リード管には、大きな熱応力を発生す
る可能性がある。これを３アドミツシヨン型の蒸気タービンの例
で説明すると、第２図Ａに示すように起動直後
は、蒸気加減弁６−１〜６−４は、No.１〜No.４の
４弁とも全開のいわゆる全周噴射運転が行なわ
れ、主蒸気リード管５−１〜５−４と第１段落ノ
ズル室７−１〜７−４は一様に暖機される。この時、各主蒸気リード管に発生したドレン
は、ドレン管８−１〜８−４、ドレン元弁９−１
〜９−４、およびドレン弁１０−１〜１０−４を
介して排出される。その後、第２図ＢおよびＣに示すように主蒸気
温度とタービン負荷が上昇すると、タービン効率
向上のため、蒸気加減弁６−１〜６−４は部分噴
射運転への切替（弁切替）が行なわれ、No.１〜No.
２の蒸気加減弁が全開した後、No.３の蒸気加減弁
が開きはじめ、それが全開した後、No.４の蒸気加
減弁が開となる。弁切替が終了すると、主蒸気リード管ドレン弁
１０−１〜１０−４は全開となる。〔背景技術の問題点〕このような従来方法では、主蒸気リード管の暖
機は十分に行なわれるように思われるが、弁切替
後に蒸気の流れている主蒸気リード管は蒸気加減
弁６−１，６−２に接続されたNo.１，２ライン５
−１，５−２のみである。他の主蒸気リード管５−３，５−４は蒸気ター
ビンの負荷上昇のため、蒸気加減弁６−１，６−
２が開となつた際には蒸気が流入することになる
が、この時点での主蒸気温度は弁切替時のものよ
りかなり高く、そのため、主蒸気リード管５−
３，５−４には大きな温度変化に依る熱応力が生
じることになる。〔発明の目的〕本発明は、従来方法における上述の如き不都合
を解消するため、弁切替後においても全ての主蒸
気リード管の暖機を適切に行ない、主蒸気リード
管に生ずる熱応力を大幅に低減することを目的と
するものである。〔発明の概要〕本発明の蒸気タービンの暖管装置は主蒸気管か
ら分岐して蒸気タービンの第１段落ノズル室の
夫々に蒸気を導く複数本の主蒸気リード管と、こ
れらの主蒸気リード弁に夫々設けた蒸気加減弁
と、前記各主蒸気リード管から分岐したドレン管
とから成る蒸気タービンの暖管装置において、部
分噴射運転への切替後、遅れて開弁される蒸気加
減弁のラインに連なるドレン管にオリフイスを設
けたものである。〔発明の実施例〕以下、第３図を参照して本発明の一実施例を説
明する。なお、第３図においては、第１図におけると同
一の部材にはそれと同じ番号を付し、詳細な説明
は省略する。第３図は４個の蒸気加減弁６−１〜６−４を備
えた３アドミツシヨン型の蒸気タービンを例示す
るもので、４本の主蒸気リード管から分岐した各
ドレン管８−１〜８−４のうち、８−３と８−４
にだけオリフイス１１−３，１１−４が設置され
ている。また４本のドレン管８−１〜８−４は個々にド
レン元弁とドレン弁を通すことなく、集合ドレン
管１２に連結され、この集合ドレン管にドレン元
弁９とドレン弁１０が介挿されている。上述の蒸気タービンの暖管装置において、弁切
替までの状態は第１図の場合と同様である。弁切替により、ドレン弁１０は閉となるが、そ
の場合でもNo.３、No.４ラインの蒸気加減弁６−
３，６−４を通過した蒸気はドレン管８−３，８
−４に設けられたオリフイス１１−３，１１−４
を通つて流れるので、主蒸気リード管５−３，５
−４は暖機されることになる。上記において、オリフイス１１−３，１１−４
の径は、主蒸気リード管の容量、タービンの負荷
上昇時間と主蒸気温度の上昇特性などに基いて定
められる。また、ウオーミング効果は、その時間にも依存
するので蒸気加減弁の開弁順序によりオリフイス
径が左右される。一般に、主蒸気リード管は各ラインとも配管
径、肉厚、および長さがほぼ等しいので、早い時
期に開く蒸気加減弁ほど、そのオリフイス径を大
きくすることが必要である。従つて第３図の実施例の場合、オリフイス１３
−３の径は、オリフイス１３−４の径よりも大き
くしなければならないことになる。第４図は、蒸気加減弁の開弁順序とタービン負
荷の関係を示したもので、Ａ，Ｂ，Ｃは４個の蒸
気加減弁を備えた蒸気タービンにおいて、２アド
ミツシヨン、３アドミツシヨン、４アドミツシヨ
ンの場合の開弁順序を示している。第４図Ａの２アドミツシヨンの場合にはNo.４ラ
インのドレン管８−４にのみオリフイス１１−４
が設けられ、同図Ｂの３アドミツシヨンの場合に
は前述のようにNo.３，No.４のラインのドレン管８
−３，８−４にオリフイス１１−３，１１−４が
設けられる。また同図Ｃの４アドミツシヨンの場合には、No.
２，No.３，No.４のラインのドレン管８−２，８−
３，８−４にオリフイス１１−２，１１−３，１
１−４を設けることになる。次表はアドミツシヨンが異なつた場合のオリフ
イス径の選定例を示している。 [Technical Field of the Invention] The present invention relates to a main steam lead pipe warming device during turbine startup. [Technical Background of the Invention] Generally, in a steam turbine, as shown in FIG. After the
4 lines from No. 4) main steam lead pipe 5-
1 to 5-4, and steam control valves 6-1 to 6, respectively.
-4, and is introduced into each of the first stage nozzle chambers 7-1 to 7-4 of the steam turbine 2. Drain pipes 8-1 to 8-4 are connected to each main steam lead pipe 5-1 to 5-4, and drains are connected to drain source valves 9-1 to 9-4 and drain valves 10-1 to 10-1, respectively.
0-4. In the steam turbine as described above, prior to startup, the main steam pipe 1 and the main steam lead pipes 5-1 to 5-5 are
-4 and the steam turbine 2 are warmed by steam, but during warming before startup, if a large amount of steam is flowed, the turbine starts rotating.
Warm-up is performed for a long time using the minimum amount of steam required. In this case, a temperature increase due to warming can only be expected up to a saturation temperature corresponding to the warming steam pressure. On the other hand, after the turbine is started, the main steam temperature rises rapidly, so there is a possibility that a large thermal stress will be generated in the main steam lead pipe connected to the steam control valve that opens late. To explain this using an example of a 3-admission type steam turbine, as shown in Figure 2A, immediately after startup, all four steam control valves 6-1 to 6-4, No. 1 to No. 4, are fully open. A so-called all-round injection operation is performed, and the main steam lead pipes 5-1 to 5-4 and the first stage nozzle chambers 7-1 to 7-4 are uniformly warmed up. At this time, the drain generated in each main steam lead pipe is drained from drain pipes 8-1 to 8-4 and drain source valve 9-1.
to 9-4, and drain valves 10-1 to 10-4. After that, when the main steam temperature and turbine load rise as shown in Figure 2 B and C, the steam control valves 6-1 to 6-4 are switched to partial injection operation (valve switching) to improve turbine efficiency. Conducted, No.1~No.
After the No. 2 steam adjustment valve is fully opened, the No. 3 steam adjustment valve begins to open, and after it is fully opened, the No. 4 steam adjustment valve is opened. When the valve switching is completed, the main steam lead pipe drain valves 10-1 to 10-4 are fully opened. [Problems in the Background Art] In such a conventional method, it seems that the main steam lead pipe is sufficiently warmed up, but after the valve is switched, the main steam lead pipe through which steam flows is connected to the steam control valve 6- No. 1, 2 line 5 connected to 1, 6-2
-1, 5-2 only. The other main steam lead pipes 5-3, 5-4 are operated by steam control valves 6-1, 6-4 due to an increase in the load of the steam turbine.
2 opens, steam will flow in, but the main steam temperature at this point is much higher than that at the time of valve switching, so the main steam lead pipe 5-
3 and 5-4, thermal stress will occur due to large temperature changes. [Object of the Invention] In order to eliminate the above-mentioned inconveniences in the conventional method, the present invention properly warms up all main steam lead pipes even after valve switching, and significantly reduces thermal stress occurring in the main steam lead pipes. The purpose is to reduce the [Summary of the Invention] The steam turbine warm pipe device of the present invention includes a plurality of main steam lead pipes that branch from a main steam pipe and guide steam to each of the first stage nozzle chambers of the steam turbine, and these main steam leads. In a steam turbine warm pipe system consisting of a steam control valve provided in each valve and a drain pipe branched from each of the main steam lead pipes, the steam control valve is opened with a delay after switching to partial injection operation. An orifice is installed in the drain pipe connected to the line. [Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIG. In FIG. 3, the same members as in FIG. 1 are given the same numbers, and detailed explanations are omitted. FIG. 3 illustrates a three-admission type steam turbine equipped with four steam control valves 6-1 to 6-4, each of which has drain pipes 8-1 to 8 branched from four main steam lead pipes. -4, 8-3 and 8-4
Orifices 11-3 and 11-4 are installed only in. Further, the four drain pipes 8-1 to 8-4 are connected to a collective drain pipe 12 without passing through the drain valves individually, and the drain main valve 9 and the drain valve 10 are connected to the collective drain pipe. It is inserted. In the steam turbine warm pipe system described above, the conditions up to the valve switching are the same as those shown in FIG. By switching the valve, the drain valve 10 is closed, but even in that case, the steam control valve 6- of the No. 3 and No. 4 lines is closed.
The steam that has passed through 3 and 6-4 is drained to drain pipes 8-3 and 8.
Orifice 11-3, 11-4 installed in -4
The main steam lead pipes 5-3, 5
-4 will be warmed up. In the above, orifices 11-3, 11-4
The diameter of the main steam lead pipe is determined based on the capacity of the main steam lead pipe, the turbine load rise time, the rise characteristics of the main steam temperature, etc. Furthermore, since the warming effect also depends on the time, the orifice diameter is influenced by the opening order of the steam control valves. Generally, each line of the main steam lead pipe has approximately the same pipe diameter, wall thickness, and length, so the earlier the steam control valve opens, the larger the orifice diameter needs to be. Therefore, in the embodiment of FIG. 3, the orifice 13
The diameter of -3 must be larger than the diameter of orifice 13-4. Figure 4 shows the relationship between the opening order of the steam control valves and the turbine load. The valve opening order in the case of is shown. In the case of 2 admissions in Figure 4A, there is an orifice 11-4 only in the drain pipe 8-4 of the No. 4 line.
In the case of the 3 admission shown in Figure B, the drain pipes 8 of the No. 3 and No. 4 lines are installed as described above.
-3, 8-4 are provided with orifices 11-3, 11-4. In addition, in the case of 4 admissions in Figure C, No.
2, No. 3, No. 4 line drain pipe 8-2, 8-
Orifice 11-2, 11-3, 1 on 3, 8-4
1-4 will be provided. The following table shows examples of orifice diameter selection for different admissions.

〔Effect of the invention〕

上述の如く、本発明は２以上のアドミツシヨン
で弁切替後の開弁を行なう蒸気タービンにおい
て、遅れて開弁される蒸気加減弁に連なる主蒸気
リード管に導入される蒸気を、そのラインのドレ
ン管に設けたオリフイスに流すようにしたから、
上記主蒸気リード管は開弁時まで高温蒸気によつ
て暖機され、従つて開弁時に高温蒸気が導入され
た際にも急激な熱応力を受けることがない。それ故、熱応力による主蒸気リード管等の劣化
は防止され、蒸気タービンの信頼性を向上させる
ことができる。 As described above, in a steam turbine in which the valve is opened after switching at two or more admissions, the steam introduced into the main steam lead pipe connected to the steam control valve that opens with a delay is transferred to the drain of that line. I made it flow through an orifice installed in the pipe, so
The main steam lead pipe is warmed up by high-temperature steam until the valve is opened, and therefore is not subjected to sudden thermal stress even when high-temperature steam is introduced at the time of opening the valve. Therefore, deterioration of the main steam lead pipe and the like due to thermal stress is prevented, and the reliability of the steam turbine can be improved.

[Brief explanation of the drawing]

第１図は従来の蒸気タービンの暖管装置を示す
系統図、第２図は蒸気加減弁の開度、主蒸気温度
および負荷の関係を示すグラフ、第３図は本発明
の蒸気タービンの暖管装置の実施例を示す系統
図、第４図は２〜３アドミツシヨンにおけるター
ビン負荷と蒸気加減弁の開弁順序を示すグラフで
ある。１……主蒸気管、２……蒸気タービン、３……
主蒸気止め弁、４……主蒸気止め弁バイパス弁、
５−１〜５−４……主蒸気リード管、６−１〜６
−４……蒸気加減弁、７−１〜７−４……第１段
落ノズル室、８−１〜８−４……ドレン管、９，
９−１〜９−４……ドレン元弁、１０，１０−１
〜１０−４……ドレン弁、１１−３，１１−４…
…オリフイス、１２……集合ドレン管。 Fig. 1 is a system diagram showing a conventional steam turbine heating pipe device, Fig. 2 is a graph showing the relationship between the opening degree of the steam control valve, main steam temperature, and load, and Fig. 3 is a diagram showing the heating pipe system of the steam turbine of the present invention. FIG. 4, which is a system diagram showing an embodiment of the pipe device, is a graph showing the turbine load and the opening order of the steam control valves in the second to third admissions. 1...Main steam pipe, 2...Steam turbine, 3...
Main steam stop valve, 4... Main steam stop valve bypass valve,
5-1 to 5-4...Main steam lead pipe, 6-1 to 6
-4... Steam control valve, 7-1 to 7-4... First stage nozzle chamber, 8-1 to 8-4... Drain pipe, 9,
9-1 to 9-4... Drain main valve, 10, 10-1
~10-4...Drain valve, 11-3, 11-4...
...Orifice, 12...Collective drain pipe.

Claims

[Scope of Claims] 1. A plurality of main steam lead pipes that branch from the main steam pipe and guide steam to each of the first stage nozzle chambers of the steam turbine, and a steam control valve provided in each of these main steam lead pipes. and a drain pipe branched from each of the main steam lead pipes, in which an orifice is installed in the drain pipe connected to the line of the steam control valve that is opened late after switching to partial injection operation. A warm pipe device for a steam turbine, characterized in that it is provided with: 2. The warm pipe device for a steam turbine according to claim 1, wherein the earlier the opening/closing order of the steam control valve is, the larger the diameter of the orifice of the line connected thereto. 3. The other end side of the drain pipe branched from each main steam lead pipe is connected to a collecting drain pipe, and a drain valve is attached to the collecting drain pipe. The steam turbine warm pipe device according to item 2.