JPS5915610A - Steam turbine - Google Patents

Abstract

PURPOSE:To improve efficiency of a steam turbine plant, by taking off extraction steam from the side approximate to a steam inlet of a low pressure turbine in a high exhaust vacuum side and the side approximate to a low pressure turbine in a low exhaust vacuum side. CONSTITUTION:Driving steam 5 is allowed to circultively flow in a high pressure turbine 6, reheater 7 and an intermediate pressure turbine 8 successively, and fed to low pressure turbines 4H, 4L. A plural number of feed water heating extraction pipes 10a-10f are provided to a place approximate to a steam inlet J of a high exhaust vacuum side low pressure turbine 4H. Extraction pipes 11a-11d are provided to a place approximate to a steam outlet R of a low exhaust vacuum side low pressre turbine 4L. A less quantity of the extraction pipes 11a-11d than the quantity of the extraction pipes 10a-10f can almost equalize an inflow of steam and a flow speed of exhaust of the low pressure turbines 4H, 4L. While a flow path of steam in a condenser 1 is never blocked. In this way, efficiency of a steam turbine plant can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-flow exhaust steam turbine equipped with a multi-pressure condenser.

In a steam turbine flint, when the amount of cooling water for the condenser is limited and the temperature of the cooling water is relatively low, it is recommended to divide the inside of the condenser into multiple rooms and install a multi-pressure condenser with a different degree of vacuum in each of the multiple rooms. It is considered advantageous to provide this. In this case, the room on the cooling water inlet side has a high degree of vacuum, and the room on the cooling water outlet side has a low degree of vacuum.

Therefore, when installing a multi-pressure condenser, it is necessary to distinguish between low-pressure turbines connected to a high-vacuum condenser and low-pressure turbines connected to a low-vacuum condenser among multiple low-pressure turbines. Therefore, the efficiency of the steam turbine plant cannot be increased unless the operating conditions of both low-pressure turbines are well balanced. The technical problems will be explained next with reference to FIG.

Generally, the exhaust loss of a steam turbine has a large effect on the efficiency of the steam turbine. The relationship between the exhaust loss and the exhaust flow rate exhibits a U-shaped characteristic as shown in FIG.

Considering only that the steam turbine operates at point M, where the exhaust loss is the minimum value, the exhaust flow velocity can be expressed as V corresponding to point M in ``2''.
Just set it to M.

Here, the exhaust flow velocity V of the turbine is determined by the following equation.

However, G: Exhaust flow rate■ = Exhaust specific volume must be increased, but the value for this person is determined by the following equation.

A=nX+rXDXL ------・
(2) However, n: Number of target exhaust flow paths D: Average diameter of the final stage blade L: Length of the final stage blade Therefore, if you try to increase the value of A, the turbine will become larger and heavier, which will increase the equipment cost. This causes an increase in operating costs.

Second, the above value of L (last stage blade length) is, for example, 26
inch, 30 inch, or 33.5 inch, which are internally standardized by manufacturers, and attempting to design and manufacture products of other dimensions would require a large amount of management costs and be uneconomical.

Due to the above-mentioned circumstances, especially the characteristic curve in Figure 1 is not V-shaped but U-shaped.
Considering the shape of the turbine, it is actually most economical to select a flow velocity VN that is slightly larger than the flow velocity VM that minimizes the turbine exhaust loss, thereby finding a compromise between making the turbine smaller.

Taking into consideration the relationship between exhaust flow velocity and exhaust loss as described above, it seems that the characteristics of the low pressure turbine that should be used in combination with the multipressure condenser described above are lacking.

In Figure 2, 1 is a multipressure capacitor,
Its interior is divided into two chambers by a partition wall 2. 3 indicates a cooling water pipe, and W indicates the cooling water flow direction.

Therefore, the IH on the upstream side of the cooling water is a high vacuum post-ice chamber, and the IL on the downstream side is a low vacuum condensation chamber.

4H is a low pressure turbine on the high exhaust vacuum side, and 4L is a low pressure turbine on the low exhaust vacuum side.

The driving steam 5 is a high pressure turbine 6, a reheater 7. It sequentially flows through the intermediate pressure turbine 8 and is supplied to the low pressure turbines 4H and 4L via the crossover pipe 9.

Low-pressure turbines 4H and 4L each have a high-vacuum condensate chamber I.
H and low vacuum condensate chamber IL are configured in a double flow type, making a total of four flow type exhaust types.

For convenience of study, the pressure inside the high vacuum condensate chamber IH is 0.06K.
g/cm' (absolute pressure), and the pressure in the low vacuum condensate chamber IL is assumed to be 0.08 to 9/Crn'' (absolute pressure).

In this case, the specific volume M of steam flowing into the high vacuum condensation chamber IH
v o = 24.2rn”7Kg, low vacuum condensate chamber IL
Specific volume of steam flowing into V t, = 18.4 m3
//Ky.

Therefore, if the exhaust flow rates G of both low-pressure turbines 4H and 4L are equal, the ratio of the exhaust flow speeds of both low-pressure turbines Vllll/
VL is approximately 1.3/1.

In this way, if we apply the fact that there is a large difference in the exhaust flow speeds of the two low-pressure turbines to the exhaust loss curve in Fig.
N), the other exhaust flow velocity is underflow velocity V++
, or excessive flow velocity V? It is understood that this results in a large exhaust loss.

In order to eliminate the above-mentioned problems using the conventional technology and make the exhaust flow speeds of both low-pressure turbines 4H and 4L almost equal, (
b) A method of setting the steam inflow rate of the high exhaust vacuum side low pressure turbine 4H to 1/1.3 of the steam inflow rate of the low exhaust vacuum side low pressure turbine 4L, and (b) All oil from the low pressure turbine is highly exhausted. A possible method is to provide them in a concentrated manner in the low pressure turbine 4H on the vacuum side.

However, if you try to create a difference in the amount of steam inflow between the two low-pressure turbines as in (a) above, unless the low-pressure turbines are made into special specifications, the stage heat drop will be too small or too large in both low-pressure turbines, resulting in turbine efficiency. lower. Furthermore, if the low-pressure turbine is made to have special specifications, manufacturing costs will increase significantly. On the other hand, if the bleed pipes are installed in a concentrated manner in the low pressure turbine 4H on the high exhaust vacuum side as in (b) above, the steam flow path in the high vacuum condensation chamber IH will be blocked and the turbine efficiency will be reduced.

The present invention has been made in view of the above-mentioned circumstances, and provides a multi-flow exhaust type steam turbine with a steam turbine gland equipped with a multi-pressure condenser, in which the steam inflow amount of a plurality of low-pressure turbines is made approximately equal, and the exhaust flow rate is It is an object of the present invention to provide a steam turbine in which the steam flow path in the condensing chamber can be made almost equal, and there is no risk of the steam flow path in the condensing chamber being unevenly blocked by the bleed pipe.

As is clear from FiiJS's explanation, if the exhaust flow speeds of multiple low-pressure turbines can be made approximately equal, it is possible to set the exhaust flow speed to reduce exhaust loss as explained with reference to Figure 1. If the amount of steam inflow into the turbines can be made uniform, it is possible to set the stage heat drop appropriately without using a specially designed low-pressure turbine.
If there is no risk of unevenly blocking the steam flow path with the bleed pipe, there is no risk of a decrease in efficiency due to the narrowness of the steam flow path, which greatly contributes to improving the efficiency of the steam turbine plant as a whole.

In order to achieve the above object, the steam turbine of the present invention includes:
In a steam turbine plant equipped with a multi-pressure condenser, air is extracted for heating feed water from multiple locations on the side close to the steam inlet of the low-pressure turbine on the high exhaust vacuum side, and air is extracted for heating the feed water from multiple locations on the side close to the steam outlet of the low-pressure turbine on the low exhaust vacuum side. The present invention is characterized in that the number of air bleeds in the low pressure turbine on the low exhaust vacuum side is smaller than the number of oil air in the low pressure turbine on the high exhaust vacuum side.

Next, one embodiment of the present invention will be described with reference to FIG. This embodiment is an improved version of the steam turbine shown in FIG. 2 by applying the present invention. The multipressure condenser 1, high vacuum condenser
, low vacuum condenser IL, bulkhead 2, cooling water pipe 3, high pressure turbine 6, reheater 7, intermediate pressure turbine 8, and crossover pipe 9 are the same as in the conventional steam turbine (Fig. 2). It is a component.

In this embodiment, the high exhaust vacuum side low pressure turbine 4H and the low exhaust vacuum side low pressure turbine 4L are respectively conventional devices (
The components are similar to the high exhaust vacuum side low pressure turbine 4H and the low exhaust vacuum side low pressure turbine 4L in FIG. 2), but as described below, the installation state of the bleed pipe is different.

In the embodiment shown in FIG. 3, J is the steam inlet of the high exhaust vacuum side low pressure turbine 4H, and K is the steam outlet. Q is the steam population of the low pressure turbine 4L on the low exhaust vacuum side, and R is the steam outlet.

A plurality of air bleed pipes 10a (six in this example) are located near the steam population J of the high exhaust vacuum side low pressure turbine 4H,
10b...10f are provided.

Bleed pipes 11a...lid are provided near the steam outlet R of the low exhaust vacuum side low pressure turbine 4L. The number of air bleed pipes provided in this low exhaust vacuum side low pressure turbine 4L is also smaller than the number of air bleed pipes provided in the above-mentioned high exhaust vacuum side low pressure turbine 4H.

The steam extracted from each of the above-mentioned bleed pipes is used to heat the feed water.

The main specifications in this actual example are as follows.

Steam flow rate flowing into crossover pipe 9: 100 tons/
The steam flow rate flowing into the low pressure turbines 4H and 4L is 500 tons/hour, and the bleed pressure in the bleed pipes 10a and 10b is 5.4 Kq/7.
m" The bleed pressure of the bleed pipes 10c and 10d is 2.7 kg/♂ The bleed pressure of the bleed pipes 10e and 10f is 1.2 Kg/♂ The bleed pressure of the bleed pipes 118 to 11d is 0.5 Kq
/cyn' Bleeding flow rate of air bleed pipes 10a and 10b = 50
Bleed air flow rate in bleed pipes 10c and 10d: 5 tons/h Bleed air flow i in bleed pipes 10e and 10e: 501-tons/h Accordingly, the exhaust flow rate of the low pressure turbine 4H on the high exhaust vacuum side is 500 tons/h. -(50X3)=350) At 77 o'clock, the exhaust flow rate of the low pressure turbine 4L on the low exhaust vacuum side is 500-50
=450) 77 o'clock.

As mentioned earlier, the specific volume of steam V I+ on the high vacuum side is 2
4.2m” 7Kg, specific volume of steam on the low vacuum side VL is 1
Since it is 8.4m”7Kg, we can convert these values into the above (
1) Substituting into the equation to calculate the exhaust flow velocity VR of the high exhaust vacuum side low pressure turbine 4H and the exhaust flow velocity VL of the low exhaust vacuum side low pressure turbine 4L, VR=350X24.2X0.90 /A=7623/
AVL=450X18.4X0.91/A=7535
/A, and VH and VL are almost equal.

Therefore, the effect of a steam turbine plant using a multi-brella condenser can be maximized by setting the final stage annulus area A so that these VH and VLO values become the VN values shown in Figure 1. I can do it.

On the other hand, when the diameters of the bleed pipes provided in the exhaust chambers of the low-pressure turbines 4L and 4H are set so that the flow velocity in the pipes is 50 m/sec, the following results are obtained.

Air bleed pipes 11a to 11d: Diameter 536 mm x 4 air bleed pipes 1
0a and 10b: 293 mm diameter x 2 bleed pipes 10C and 10d: 382 mm diameter x 2 bleed pipes 10e and 10f
: Diameter 527 ran
That is, air is extracted from the low pressure stage in the stage of the turbine, and air is extracted from the high pressure stage near the steam population J of the high exhaust vacuum side low pressure turbine 4H, that is, the high pressure stage in the stage of the turbine, and the air is extracted from the high pressure stage in the high exhaust vacuum side low pressure turbine 4H. If the number of air extracted from the low exhaust vacuum side low pressure turbine 4L is made smaller than the number of air extracted from the low pressure turbine 4H, both low pressure turbines 4H.

The volumes of the 4L bleed exhaust pipes can be made almost equal, and it is possible to prevent the steam flow/path from being unevenly blocked.

A trial calculation and comparison of the subtotal cross-sectional area of the bleed pipe in this example (approximate estimate ignoring the wall thickness of the pipe) shows that the cross-sectional area of the bleed pipe in the high vacuum condensate chamber IH: approximately 800 cm, and the low vacuum condensate The cross-sectional area of the air bleed pipe in the water chamber IL is about 90 mm and p1 are approximately equal, so the efficiency of the high exhaust vacuum side low pressure turbine 4H and the low exhaust vacuum side low pressure turbine 4L can be kept to the same level.

The above embodiment describes the case where two low-pressure turbines are installed in a multi-pressure condenser divided into two chambers, but the present invention provides a case in which three or more low-pressure turbines are installed in a multi-pressure condenser divided into three or more chambers. It can also be applied to a steam turbine plant with a turbine installed, and the same effect as above can be obtained. Since independent oil and air systems are provided for each of the multiple low-pressure turbines, there is no need to specify the stage pressure between each low-pressure turbine, so there is no possibility of a reduction in turbine internal efficiency due to constraints on the turbine stage pressure. None.

As described in detail above, the present invention provides a steam turbine plant equipped with a multi-pressure condenser, in which extraction air for heating feed water is taken from multiple locations on the side close to the steam inlet of a low-pressure turbine on the high-exhaust vacuum side, and Extract air from the side near the steam outlet of the low-pressure turbine on the vacuum side, and
By making the number of air bleeds in the low pressure turbine on the low exhaust vacuum side smaller than the number of oil air in the low pressure turbine on the high exhaust vacuum side, the steam inflow amount and exhaust flow velocity of the plurality of low pressure turbines can be made almost equal. Moreover, since there is no risk of the steam flow path in the condenser being unevenly blocked by the bleed pipe, the efficiency of the steam turbine plant can be improved.

[Brief explanation of the drawing]

Figure 1 is a chart showing the relationship between exhaust flow velocity and loss of air;
The figure is a schematic sectional view of an emitter steam turbine plant equipped with a multipressure condenser, and FIG. 3 is a schematic sectional view of an embodiment of the steam turbine of the present invention. 1...Multi-pressure capacitor, IH...High vacuum condensate chamber, IL...Low vacuum condensate chamber, 2...Partition wall, 3
... Cooling water pipe, 4H ... High exhaust vacuum side low pressure turbine, 4 L ... Low exhaust vacuum side low pressure turbine, 5 ... Drive steam, 6 ... High pressure turbine, 7 ... Reheater , 8・
...Intermediate pressure turbine, 9...Crossover pipe, 10a
, 10b, 10c. 10d, 10e, 10f... Bleed pipes provided in the high exhaust vacuum low pressure turbine, lla, llb, llc. lid...Air bleed pipe installed in a low exhaust vacuum low pressure turbine. Agent Patent Attorney Masami Akimoto

Claims (1)

[Claims] 1. In a steam turbine plant equipped with a multi-pressure condenser, the extraction air for heating the feed water is taken from multiple locations near the steam inlet of the low-pressure turbine on the high exhaust vacuum side, and is also extracted from the steam outlet of the low-pressure turbine on the low exhaust vacuum side. A steam turbine characterized in that air is extracted from a nearby side, and the number of air bleeds in the low pressure turbine on the low exhaust vacuum side is smaller than the number of oil air in the low pressure turbine on the high exhaust vacuum side.