JP2001193417A - Directly contacting type condenser for axial-flow exhaust turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adopt an axial-flow exhaust type steam turbine by providing a directly contacting type condenser, capable of preventing water induction in a steam turbine power generating plane where the directly contacting type condenser is adopted. SOLUTION: In the directly contacting type condenser formed in a type where a cooling water line and a circulating water line are disposed between a cooling tower, and the direct contacting type condenser and a circulating water pump is interposed in the circulating water line, an erecting part is formed on the cooling water line, a siphon breaker composed of a branch pipe and a valve is connected to the vicinity of the top part of the erective part, and thereby, water is prevented from flowing from the cooling water line and the circulating water line at the time of circulating water pump trip, and also water induction is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct contact type condensing device used for a geothermal power plant or the like.

[0002]

2. Description of the Related Art A condensing device cools and condenses the exhaust gas of a steam turbine, creates a vacuum, increases the heat drop of steam in the steam turbine, increases the thermal efficiency, and collects the condensed water. Conventionally, in a geothermal power plant or the like, as shown in FIG. 3, a downward exhaust type arrangement in which a steam turbine 1 is disposed above a condenser 2 is generally used. In order to shorten the process (in the case of a downward exhaust type, the steam turbine must be installed after installing the condenser), as shown in FIG. Placement is increasing. .

However, in this arrangement, since the steam turbine 1 and the condenser 2 are joined through the turbine exhaust duct 3 with little difference in level, the steam turbine 1 is installed in a circulating water line. When a circulating water pump (not shown) trips (failure stop) or the like occurs, a phenomenon in which water flows from the condenser 2 to the steam turbine 1 side, that is, a so-called water retention may occur.

[0004] Especially in a direct contact condenser commonly used in geothermal power plants, the cooling water is sprayed directly into the condenser, so that when the circulating water pump trips, the water level of the condenser is reduced. This is dangerous because it is expected to rise sharply, and there is a high possibility of causing war-tion.

[0005] For this reason, when a type in which the steam turbine 1 and the condenser 2 are arranged at the same level as shown in FIG. 4 is adopted, the steam turbine 1 and the condenser 2 are arranged at a certain height. The exhaust pipe (turbine exhaust duct 3) is connected to prevent the water in the condenser 2 from easily flowing into the steam turbine 1 side.

[0006]

However, in this method, the pressure loss from the outlet of the last blade of the steam turbine to the condenser is increased, and the performance of the plant is reduced. Furthermore, since the turbine exhaust duct must be arranged at a certain height, the height of the turbine building must be increased,
There were problems such as the effect of reducing construction costs being reduced.

On the other hand, in order to improve the plant performance, it is effective to employ a so-called axial exhaust turbine which discharges the exhaust of the steam turbine in the axial direction of the turbine. In the case of using an axial exhaust turbine in a plant that uses a turbine, the risk of the above-mentioned war reduction becomes more and more, and the adoption of an axial exhaust turbine in a plant that employs a direct contact condenser has not been realized. Was.

[0008]

According to the first aspect of the present invention, a cooling water line and a circulating water line are arranged between a cooling tower and a direct contact condenser. In the direct contact type condenser in which a circulating water pump is interposed in the circulating water line, a rising portion is formed in the cooling water line, and the cooling water line includes a branch pipe and a valve near the top of the rising portion. A siphon breaker is connected.

The invention according to a second aspect is characterized in that the branch pipe is connected to a pressurized gas supply source or is open to the atmosphere.

According to a third aspect of the present invention, the pressurized gas is nitrogen gas or air.

According to a fourth aspect of the present invention, the valve of the siphon breaker is opened when the circulating water pump trips.

The invention according to claim 5 is characterized in that a check valve is interposed in the circulating water line.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIG. Reference numeral 11 denotes an axial exhaust type steam turbine, 12 denotes a direct contact type jet spray condenser, and the steam turbine 11 and the condenser 12 are connected by a turbine exhaust duct 13. Is arranged slightly higher than the condenser 12.

A cooling tower 14 is provided with a cooling water line 15 and a circulating water line 16 between the cooling tower 12 and the condenser 12.
A rising portion 17 is provided at an intermediate portion of the cooling water line 15, and a siphon breaker 20 including a branch pipe 18 and a valve 19 is connected near the top of the rising portion 17. The branch pipe 18 is connected to a nitrogen gas reservoir (not shown). When there is no nitrogen gas supply source in the plant, a configuration in which the plant is connected to a compressed air reservoir may be adopted. If there is room in the apparatus, the diameter of the branch pipe may be increased to directly suction the atmosphere. Circulating water line 16
Is provided with a circulating water pump 21 and a check valve 22.

In the above-described apparatus, the main steam flows into the steam turbine 11 from the main steam pipe 23, and after working, flows into the condenser 12 through the turbine exhaust duct 13 as turbine exhaust. The condenser 12 has a plurality of watering pipes 2
The steam condenses upon coming into contact with the cooling water sprinkled from 4 and becomes condensed water, which accumulates in the lower part of the condenser together with the cooling water. The mixed water of the cooling water and the condensed water (hereinafter simply referred to as “condensed water”) reaches the cooling tower 14 via the circulating water line 16, the circulating water pump 21, and the check valve 22, where it is air-cooled and the temperature is Descend.

The cooling water cooled in the cooling tower 14 passes through a cooling water line 15 and is again sprinkled into the condenser 12 from a sprinkling pipe 24 of the condenser 12. At this time, assuming that the transfer pressure of the cooling water from the cooling tower 14 to the condenser 12 is P, P = atmospheric pressure−condenser internal pressure + cooling tower cold water tank head−pressure loss. Cooling water is sent by pressure P from the cooling tower to the condenser without power.

In such an apparatus, the circulating water pump 2
When 1 is tripped, the condensate stops being discharged from the condenser 12, while the condenser 12 tries to keep cooling water flowing from the cooling tower 14. Also, the condensate tends to flow backward from the circulating water line 16 to the condenser 12 from the cooling tower 14 side due to the pressure P.

At this time, in response to the trip signal of the circulating water pump 21, the valve 19 is rapidly and fully opened, and high-pressure nitrogen gas flows from the nitrogen gas reservoir (not shown) into the cooling water line 15 and flows into the cooling tower 12 of the cooling water. Is stopped. In addition, since the check valve 22 is provided in the circulating water line 16, backflow of the condensed water from the cooling tower 14 side to the condenser 12 through the circulating water line 16 is prevented.

As described above, the siphon breaker 20 is provided in the cooling water line 15 and the check valve 2 is provided in the circulating water line 16.
Since the cooling water 2 is provided, the cooling water is prevented from flowing into the condenser 12, the backflow of the circulating water is prevented, and the risk of water induction into the steam turbine 11 is reduced.

Although the position of the steam turbine 11 is determined in consideration of the maximum rise level of the water level of the condenser 12, it is not necessary to arrange the turbine exhaust duct 13 at a high position as in the prior art. Costs can be reduced. Further, since the installation of the steam turbine 11 and the condenser 12 can be performed almost independently, an effect of shortening the process can be obtained.

The condenser 12 of the jet spray type shown in FIG. 1 has good heat exchange efficiency and can improve plant performance. Further, since the risk of water induction is reduced by the present invention, the steam turbine 11 can adopt an axial exhaust type. When the axial exhaust type is adopted, the steam turbine exhaust is exhausted almost straight from the steam turbine toward the condenser, so the pressure loss in the turbine exhaust duct is smaller than in the conventional type, which is advantageous in terms of performance. Become.

By expanding the shape of the turbine exhaust duct from the steam turbine to the condenser, a pressure recovery effect can be obtained. (Dynamic pressure decreases by decreasing the flow velocity of the turbine exhaust from the outlet of the steam turbine final blade toward the condenser. On the other hand, the sum of the dynamic pressure and the static pressure of the fluid is kept constant. The static pressure at the outlet is smaller than the pressure inside the condenser.) On the other hand, the pressure inside the condenser is determined by the heat balance around the condenser. If the conditions are the same, there is no difference between the axial exhaust type and the conventional type.

Therefore, if the conditions on the condenser side are the same,
When the axial exhaust type is adopted, the heat drop of the steam inside the turbine is increased and the plant performance is improved as compared with the conventional type.

Next, a second embodiment of the present invention will be described with reference to FIG. This example shows a case where the condenser 25 is of a downward sprinkling type. The cooling water is supplied to the header 2 provided on the condenser 25.
6 is temporarily stored and then sprinkled downward into the condenser 25. Other configurations and operations are the same as those shown in FIG. 1, and are denoted by the same reference numerals and description thereof is omitted. However, in the same manner as in FIG. 1, the risk of water induction is reduced.

The downsprinkling method in FIG. 2 does not require a sprinkler pipe in the condenser as compared with the jet spraying method in FIG. 1, so the structure is simpler and the pressure loss can be reduced. It is necessary to take measures such as increasing the strength of the wall or providing sufficient columns for the provision at the top.

[0026]

In summary, according to the present invention, the axial exhaust steam turbine can be adopted in a plant using a direct contact condenser by reducing the risk of water induction. When an axial exhaust type turbine is adopted, the turbine exhaust is exhausted almost straight from the steam turbine toward the condenser, so that the pressure loss in the turbine exhaust duct is reduced and the performance is advantageous compared to the conventional type. A plant can be realized. Further, by increasing the shape of the turbine exhaust duct from the steam turbine to the condenser, a pressure recovery effect can be obtained, so that plant performance can be improved.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a first embodiment of the present invention.

FIG. 2 is a system diagram showing a second embodiment of the present invention.

FIG. 3 is an explanatory view showing a conventional downward exhaust type.

FIG. 4 is an explanatory view showing a conventional same-level arrangement.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Steam turbine 12 Condenser 13 Turbine exhaust duct 14 Cooling tower 15 Cooling water line 16 Circulating water line 17 Rising part 18 Branch pipe 19 Valve 20 Siphon breaker 21 Circulating water pump 22 Check valve 23 Main steam pipe 24 Sprinkling pipe 25 Condenser Water bowl 26 header

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Akira Yamada 5-717-1, Fukahori-cho, Nagasaki-shi, Nagasaki Prefecture Inside Nagasaki Research Laboratory, Mitsubishi Heavy Industries, Ltd. (72) Ryutaro Mori 5-717 Fukahori-cho, Nagasaki-city, Nagasaki Prefecture No. 1 Inside the Nagasaki Research Laboratory of Mitsubishi Heavy Industries, Ltd.

Claims (5)

[Claims] 1. A direct contact type condenser in which a cooling water line and a circulating water line are arranged between a cooling tower and a direct contact condenser, and a circulating water pump is interposed in the circulating water line. In the apparatus, a rising portion is formed in the cooling water line, and a siphon breaker including a branch pipe and a valve is connected near a top portion of the rising portion, wherein a direct contact condensate for an axial exhaust turbine is provided. apparatus. 2. The direct condensing device for an axial exhaust turbine according to claim 1, wherein the branch pipe is connected to a pressurized gas supply source or is open to the atmosphere. 3. The direct contact condenser according to claim 2, wherein the pressurized gas is nitrogen gas or air. 4. A direct contact condenser for an axial exhaust turbine according to claim 1, wherein the valve of the siphon breaker is opened when the circulating water pump is tripped. 5. The direct contact condenser for an axial exhaust turbine according to claim 4, wherein a check valve is interposed in the circulating water line.