JPH0783004A - Casing cooling/heating device - Google Patents

Abstract

PURPOSE:To increase the cooling or heating effect of the tightening bolts and flanges of a casing while thermal energy to be lost uselessly is being maintained small. CONSTITUTION:Center holes 11 respectively penetrating axially are pierced at adjoining tightening bolts 7. These center holes 11 are connected to each other by means of a connection pipe 12 to be provided separately from flanges 1a, 1b. Also, a connection hole 3 is provided for connecting bolt holes 2 mutually, according to the conventional technique.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casing cooling and heating apparatus suitable for recovering heat energy from steam used for cooling or heating a casing for a steam turbine and a fastening bolt for a flange.

[0002]

2. Description of the Related Art In a steam turbine, a casing plays a very important role in expanding and working as steam as a working medium. This casing generally has a structure in which it is vertically divided into two parts at the position of the turbine shaft, and the upper half part is called the upper half casing and the lower half part is called the lower half casing to distinguish the two. In order to prevent the high-temperature and high-pressure steam flowing inside from the split part of the upper and lower half casings, that is, the joint surface, to leak out, the joint surface must be in close contact, and many tightening bolts are used there. To be done. Normally, bolt holes that penetrate in the vertical direction are drilled in the flanges that project to the outside of both casings, and tightening bolts are inserted there to ensure close contact with the joint surface.However, the steam conditions of the steam turbine will increase further. Along with this, the tightening force by the tightening bolts has become strong, and the flange thickness and area tend to increase in order to maintain rigidity against this force.

As the thickness and area of the flange increase, the heat capacity of the flange portion increases and the heat conduction decreases, resulting in a difference in steam temperature between the inside and outside of the double casing or a temperature between the steam and the atmosphere outside. Because there is a difference,
Large thermal stress is generated in the flange portion, causing deformation.

The most effective measure for reducing the thermal stress generated in the casing is to feed low-temperature steam for cooling into bolt holes formed in the flange. Hereinafter, this method will be described with reference to the drawings.

In FIG. 4 (a), the casing shows the upper half casing 1, but the lower half casing has a similar structure. A large number of bolt holes 2 are formed in the flange 1a of the upper half casing 1. Communication holes 3 are formed between the bolt holes 2 and the adjacent bolt holes 2, respectively, so that cooling steam can flow from the steam inlet 4 to the steam outlet 5. In this example, the cooling steam is extracted from a suitable turbine stage in the casing for cooling, and there is also a method of introducing the cooling steam from outside the casing. This method is shown in FIG.
In the figure, reference numeral 6 is an external steam introducing pipe connected to the steam inlet 4, and the low temperature steam is supplied to the casing through the external steam introducing pipe 6.

The cooling action in both of the above-mentioned systems will be described with reference to FIG.

This figure shows a cross section of the flange 1a together with the flange 1b of the upper half casing. Both the flanges 1a and 1b are firmly tightened by a flange tightening bolt 7 and a nut 8 inserted through a bolt hole 2. Has been.

The cooling steam enters the bolt hole 2 from the communication hole 3 of the flange 1b and flows from the top to the bottom while rotating around the tightening bolt 7 to cool, and then passes through the communication hole 3 of the flange 1a to the next tightening bolt. It flows to the bolt hole 2 with 7. Further, while flowing around the tightening bolt 7, it flows from the bottom to the top to be cooled, and then flows to the communication hole 3 of the flange 1b. In this way, it becomes possible to cool both the flanges 1a and 1b and the tightening bolt 7. It should be noted that this system may be used for a heating action so as to keep the vapor temperature higher than the flange metal temperature, in addition to providing the cooling action to the flange portion.

[0009]

As described above, the rigidity is maintained by increasing the thickness and area of the flange of the casing in accordance with the improvement of the steam condition of the steam turbine.
A method of feeding cooling steam is used to reduce the thermal stress in this portion, but when the steam conditions of the steam turbine become higher in temperature and pressure, the flanges 1a and 1b are less likely to deform, that is, more At the same time as taking into consideration the adoption of a highly rigid shape, the method of feeding cooling steam to the tightening bolt 7 must be devised more than before.

That is, as is apparent from FIG. 5, the cooling of the shaft portion of the tightening bolt 7 has a cooling effect by keeping contact with cold steam, but the tightening bolt 7 screwed with the nut 8 is used. No steam flows through the screw part of the, the contact with cold steam is not achieved, and the cooling effect is impaired.

Further, it is conceivable that the flow rate of the cooling steam used increases with the change of the method of feeding the cooling steam, and on the other hand, even if it is dealt with by simply increasing the flange thickness and the area. The flow rate of cooling steam sent to the casing flange needs to be increased more than ever.

At this time, if the extracted steam of the steam turbine as shown in FIG. 4 (a) is used to cover this, the above-mentioned increase will occur even though the heat energy consumed by the extracted air is large even in the conventional case. When the amount is added, the heat energy that is wasted is finally increased, which is a problem that cannot be ignored.

Therefore, an object of the present invention is to provide a casing cooling device which further enhances the cooling or heating effect of the flange of the casing and the tightening bolts while keeping the heat energy wasted as little as possible. is there.

[0014]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a steam extracted from a steam turbine stage into flanges of the upper and lower casings and a plurality of fastening bolts integrally connecting both flanges. Alternatively, in a casing cooling / heating device for cooling or heating by sending steam supplied from the outside, at least the fastening bolt is cooled or heated axially from the inside in parallel with the first cooling passage for the flange and the outer surface of the fastening bolt. The second cooling passage is provided.

[0015]

The present invention mainly provides a passage (referred to as a first passage) for obtaining a cooling effect on the outer surface of the flange and the tightening bolt.
A second cooling passage is provided for cooling the tightening bolt independent of the first cooling passage from the inside in the axial direction. Both cooling passages are parallel to each other, and cooling steam can flow in each.

Cooling steam extracted from a suitable steam turbine stage is introduced into the second cooling passage. The cooling steam flows into the tightening bolt, flows along the axial direction, and cools from the inside.

As described above, the tightening bolt is cooled from the inside as well as the outer surface by the cooling steam flowing through the first and second cooling passages, so that the screw bolt can be effectively cooled including the screw portion.

The cooling steam introduced to the second cooling passage is the first
The heat energy consumed except for work increases because the air is extracted separately from the one used for the cooling passage.

Therefore, in the present invention, the thermal energy of all the steam used for cooling the flange of the casing and the tightening bolt is recovered in the condensate of the condensate system. Therefore, all used steam is collected in the feed water heater.
This recovery improves the thermal efficiency in the turbine cycle as follows.

The energy balance in the feed water heater is determined by the following equation.

G ₁ · (h ₂ −h ₁ ) = G ₂ · (h ₃ −h ₄ ) ... (1) where G ₁ = condensate flow rate h ₁ = feed water heater outlet feed enthalpy h ₁ = feed water Heater inlet feed water enthalpy G ₂ = cooling steam amount h ₃ = feed water heater inlet steam enthalpy h ₄ = feed water heater outlet drain enthalpy On the other hand, the turbine room heat consumption rate HR can be calculated by the following equation.

[0022] _{HR = (G M · h M} -G T · h T) / L .................. (2) Here, G _M = main steam flow rate h _M = main steam enthalpy L = generator output G _T = being equal inflow and outflow of steam in the boiler inlet feedwater flow rate h _T = boiler inlet feedwater enthalpy _{boiler, G M = G T ............................................. (} 3) Becomes Further, in accordance with the turbine cycle prior _{art, G T = G 1, h} T = h 1 ..................... (4) next, in accordance with the turbine cycle present _{invention, G T = G 1, h} T = h 2 ………………… (5) In consideration of the above, when calculating the turbine chamber heat consumption rate HR _{1 in the} turbine cycle according to the related art and the turbine chamber heat consumption rate HR ₂ in the turbine cycle according to the present invention, HR ₁ = {G ₁ (h _M −h ₁ )} / L ……………… (6) HR ₂ = {G ₁ · (h _M −h ₂ )} / L ……………… (7). Therefore, the ratio that contributes to the improvement of thermal efficiency ΔH
R is as follows.

ΔHR = (HR ₁ −HR ₂ ) / HR ₁ = (h ₂ −h ₁ ) / (h _M −h ₁ ) ……………………………… (8) = (G ₂ / G ₁ ) × (h ₃ −h ₄ / h _M −h ₁ ) ………… (9) In an attempt, improve the thermal efficiency of a 100 MW class steam turbine with a main steam pressure of 250 atg and a main steam temperature of 550 ° C. Calculate. Assuming the values are as follows: G ₁ = 300,000 (kg / hr) G ₂ = 1,000 (kg / hr) h _M = 800 (kcal / kg) h ₁ = 100 (kcal _{/ kg) h 3 = 700 (} kcal / kg) h 4 = 150 (kcal / kg) △ HR = (1,000 / 300,000) × (700-150 / 800-
100) = 0.003 = 0.3%.

Thus, by recovering the steam used for cooling the flange of the casing and the tightening bolts to the condensate of the condensate system, wasteful heat energy can be greatly reduced.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the flange 1 along with the flange 1b.
2 shows two cooling passages for the cooling steam formed in a. The second cooling passage has a central hole 11 that penetrates the tightening bolt 7 in the axial direction. Further, these center holes 11 are communication pipes 12 provided slightly apart from the flanges 1a and 1b.
Are communicating with each other. In the present embodiment, the passage for cooling steam, which includes the bolt hole 2 and the communication hole 3 communicating with the bolt hole according to the conventional technique, is referred to as a first cooling passage.

In FIG. 2, the steam outlet 5 of the flange 1a
And, the steam pipe 15 is connected from the steam header 13 connected to the connecting pipe described later to the condensate feed water heater 14, and the cooling steam is exchanged with the condensate flowing in the feed water heater 14. is doing. In the figure, reference numeral 16 is a condensate pump, which raises the pressure of the condensate and sends it to the feed water heater 14.

Next, the operation of the above configuration will be described.

Cooling steam flowing out of the casing 1 through the flanges 1a, 1b of the casing 1 and the fastening bolts 7 through the first and second cooling passages is collected in the steam header 13 and then passed through the steam pipe 15 to feed water heater 14. Will be collected. Condensate is supplied to the feed water heater 14, and the steam comes into contact with the condensate flowing in the heat transfer tube across a wall surface to lose sensible heat and condense to form drain. This drain further flows out from the inside of the feed water heater and flows to a device for receiving the lower temperature drain on the downstream side, for example, another feed water heater or the like.

On the other hand, the cooling action in the casing 1 is
In addition to the flow through the conventional bolt hole 2, the flow through the central hole 11 that axially penetrates the tightening bolt 7 is maintained, thereby greatly improving. That is, the connecting pipe 12 below the flange 1a
The cooling steam flowing from flows from the lower side to the upper side in the center hole 11 of the tightening bolt 7, and cools the tightening bolt 7 from the inside during this. The cooling steam flows from the center hole 11 to the flange 1b.
The central hole 1 of the next tightening bolt 7 that reaches the upstream connecting pipe 12
The inside of 1 is made to flow from the upper side to the lower side, and similarly, the tightening bolt 7 is cooled from the inside.

As described above, the tightening bolt 7 can cool the entire area including the threaded portion screwed with the nut 8 by the flow of the cooling steam formed inside. The amount of extracted steam is increased by this independent second cooling passage,
The heat energy other than that lost in the above cooling can be recovered by the heat recovery means of FIG. 2, and the heat energy is not wasted.

Another embodiment of the present invention will be described with reference to FIG.

In this embodiment, apart from the steam header 13, a steam outlet 1 communicating with a bolt hole 2 in the middle of the flow direction of the cooling steam.
7 and a steam header 18 connected to a connecting pipe (not shown)
The steam pipe 20 is connected from the intermediate steam header 18 to the condensate system feed water heater 19.

This is because the flow rate of the cooling steam is reduced in the portion of the tightening bolt 7 where the thermal stress is not so severe that heat is exchanged with the condensate flowing through the condensate system at a high temperature, and more heat is transferred to the turbine cycle. The cooling steam flowing from the steam outlet 17 and the connecting pipe is intended for recovery, and the steam header 1
8, then feed water heater 19 through steam pipe 20
Will be collected.

According to this embodiment, it is possible to recover high-temperature heat energy, and it is possible to further improve thermal efficiency by reducing the amount of heat consumed for cooling.

In the above two embodiments, the cooling action is mainly described, but it goes without saying that each of the above embodiments can be applied for the heating action or the warming action for flowing the high temperature steam.

Further, the steam embodiment can be applied to not only the cooling function obtained by the extracted steam in the casing 1 but also the method of introducing the cooling steam from the outside (see FIG. 4B). .

Further, the structure of the flanges 1a and 1b of the casing 1 may be the same as that shown in FIG. 5 when it is limited to obtaining a heating action.

[0039]

As described above, in the present invention, the fastening bolt is cooled or heated from the inside in the axial direction in parallel with the first cooling passage for cooling or heating the flange of the casing and the outer surface of the fastening bolt. Since the second cooling passage is provided, the tightening bolt can be cooled from the inside together with the outer surface, and the cooling effect can be further enhanced.

Moreover, since the steam used for cooling in the first and second cooling passages is both collected in the feed water heater of the condensate system and heat-exchanged with the condensate, the heat energy consumed except for work. Can be kept low.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a casing cooling and heating device according to the present invention.

FIG. 2 is a system diagram showing an embodiment of a casing cooling / heating device according to the present invention.

FIG. 3 is a system diagram showing another embodiment of the present invention.

FIG. 4 is a system diagram showing an example of a conventional device.

FIG. 5 is a cross-sectional view showing an example of a conventional device.

[Explanation of symbols] 1a, 1b ... Flange 2 ... Bolt hole 3 ... Contact hole 7 ... Tightening bolt 11 ... Center hole 12 ... Contact pipe 13, 18 ... Steam header 14, 19 … Water heater

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsuyoshi Fukui 1-1-1, Shibaura, Minato-ku, Tokyo Inside Toshiba Head Office

Claims (3)

[Claims] 1. Cooling or heating by sending steam extracted from a steam turbine stage or steam supplied from the outside to flanges of upper and lower casings and a plurality of tightening bolts integrally connecting both flanges. In the casing cooling / heating device for a vehicle, a second cooling passage for cooling or heating at least the fastening bolt along the axial direction from the inside is provided in parallel with the first cooling passage for the flange and the outer surface of the fastening bolt. A casing cooling and heating device. 2. The steam used for cooling or heating in the first and second cooling passages is collected by a condensate feed water heater and heat-exchanged with the condensate. The casing cooling and heating device according to 1. 3. Among the steams passing through the first and second cooling passages, the steam to be continuously used for cooling or heating remains, and the other steam is recovered from the middle of the cooling passage to a condensate feed water heater and recovered. The casing cooling / heating device according to claim 2, wherein heat exchange with water is performed.