JPS59129385A - Cooling water system for condenser - Google Patents

Abstract

PURPOSE:To unnecessitate to reduce a load on a plant at the time of transferring to a back washing operation or to a forward washing operation, by a method wherein a back washing valve connecting a water-supplying pipe and a water-discharging pipe to each other and a bypass pipe led out from a rear water chamber are provided for a 1- tube-nest 2-pass condenser. CONSTITUTION:The water-supplying pipe 10 and the water-discharging pipe 11 in the 1-tube-nest 2-pass condenser are connected to each other by the back washing valve 9 provided with 4 ports, and the first valve 13 is incorporated in the water-discharging pipe 12 on the downstream side of the valve 9. The bypass pipe 15 is led out from the rear water chamber 3, and the second valve 16 is incorporated in the pipe 15, the outlet end of which is led to the water-discharging side. In a back washing condition, a stop valve 8 and the first valve 13 are opened, while the second valve 16 is closed. Therefore, cooling water introduced into a cooling water pipe 7 through an intake pump 6 is introduced into the condenser 1 through the stop valve 8, the back washing valve 9, the pipe 10 and an inlet water chamber 2a, absorbs heat at an inlet tube nest 5a from a turbine exhaust gas flowing on the outside of the tube nest 5a, then again absorbs heat when flowing through a tube nest 5b after flowing through the rear water chamber 3, and is discharged through the first valve 13.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a cooling water system in a tube bundle cobus condenser.

[Technical background of the invention]

In a power generation plant, the turbine exhaust gas that has completed its work in the turbine is led to a condenser, where it is cooled and condensed to form water, which is then reintroduced into the boiler or heat exchanger.

When the turbine exhaust discharge is small, the condenser has a single tube bundle configuration, and when the number of required cooling water needles is small, the number of condenser cooling pipes is small and the length of the cooling pipes is long. Therefore, a tube bundle Upass type condenser is used, in which the tube bundle is divided into two sections and the cooling water flows back and forth within the tube bundle.

Seawater is usually used as cooling water for condensers, but
Since seawater contains foreign substances such as shellfish and wood chips, there is a risk that these foreign substances may clog the cooling pipes or block the artificial side of the cooling pipes.

Therefore, in power plants, in order to remove foreign matter,
A so-called backwash operation, in which cooling water flows from the opposite direction of the cooling pipes, should be performed. The number of times this backwashing operation is performed varies depending on the wrinkles of the foreign material, but in most cases, it is performed at a rate of 787 times.

In a system that performs backwash operation, a backwash valve is used that is equipped with V boats and changes the direction of water flow by switching a built-in valve body.

FIG. 1 shows the cooling water system of a /tube bundle λ/cross-type four-water tank equipped with this backwash valve. In the same figure, the condenser/ is the front water tank! The rear water chamber β is divided into an inlet ice chamber, 28, and an outlet ice chamber, 21) by a cutting board. The multiple cooling pipes arranged in P9 connect the inlet pipe bundle 3'a that connects the inlet ice chamber 28 and the rear water chamber 3, and the rear A chamber 3 and the outlet water chamber c. It is separated by V' from the outlet tube bundle jb.

- At the time of a washing failure, the cooling water introduced into the cooling water pipe 7 by the water intake pump B is transferred to the stop valve g, the backwash valve 7, and the pipe 10.
It flows into the inlet ice chamber 28 through the water heater, flows through the inlet pipe bundle 3-a in the water heater, the rear water chamber 3, and the outlet pipe bundle S1:1, exchanges heat with the turbine exhaust gas, and then exits. Himuro 2b,
The water is drained through the pipe//, the backwash valve, the pipe/2, and the first valve 13.

During backwash operation, as shown in FIG. 2, the direction of the flow of cooling water is reversed by rotating the valve body 7a of the backwash valve qO. In other words, the backwash valve 7 is activated by the water intake pump B.
The cooling water sent to the pipe flows out from the outlet ice chamber,
2b, outlet tube bundle b, rear water chamber 3, inlet tube bundle ja
[After flowing through ij and performing heat exchange, it flows through inlet ice chamber ja, piping /θ, backwash valve, piping /, 2, and first valve /3 to be drained.

By the way, when the backwash valve shifts from the normal wash state to the backwash state, as shown in Fig. 3, the cooling water that has also flowed into the cooling water pipe 7 is diverted to the pipe 10° where there is a lot of resistance. A state in which water is drained directly from the pipe 12 without flowing in is traced.

Figure 3 shows how the flow of cooling water flowing into the condenser/condenser changes depending on the displacement of the valve body a of the valve. As is clear from this figure, when the valve body is facing the normal flush side, the
The cooling water that was flowing as a forward flow gradually decreases according to the displacement of the valve body, and once the flow rate reaches zero, it begins to flow to the backwash side and increases by 700%.

[Problems with back technology]

The condenser is installed for the purpose of condensing the turbine exhaust gas, so if the condition of the cooling water flow meter occurs even for a short time as mentioned above, it will not be able to bear 100% of the load, and the degree of vacuum will decrease. This will cause the power plant to trip.

In order to avoid this situation, conventionally, the set load of the power generation plant is lowered by about a factor of 30 before starting the backwash operation, and then the backwash operation is started. This also applies to the transition from backwash operation to forward wash operation.

However, increasing or decreasing the load each time the transition to backwash operation or forward wash operation complicates the operation of the power plant, and load control cannot be performed in a short period of time. The thermal efficiency of the plant decreases, which becomes a bottleneck in improving plant thermal efficiency. In addition, the number of plant load operations for switching between forward and backwash operations is much greater than load operations for other reasons, which is a factor in lowering the reliability probability of the power plant.

[Purpose of the invention]

The present invention has been made to eliminate the drawbacks of the prior art described above, and aims to provide a cooling water system for a condenser that eliminates the need to reduce the plant load when transitioning to backwash operation and forward wash operation. This is the purpose.

In order to achieve the above object, the present invention introduces the cooling water introduced into the water supply pipe from the water intake pump into the inlet pipe bundle of the condenser through the inlet ice chamber, and directs the cooling water flowing out from the inlet pipe bundle through the rear water chamber. The cooling water that infiltrated the outlet pipe bundle and flowed out from this outlet pipe bundle into the outlet water chamber was discharged through the drainage pipe./In the pipe bundle 2 bus condenser; The above water supply pipe and water extraction pipe were equipped with four boats. Connected by a backwash valve, a first valve is installed on the water pipe downstream of this backwash valve, and a bypass pipe is led out from the rear ice chamber, and a second valve is installed on the pipe of this bypass pipe. It is characterized in that the outlet end of the built-in pipe is guided to the water discharge side.

[Embodiments of the invention]

Hereinafter, embodiments of the present invention and their effects will be described with reference to FIGS. 5 to 1. In addition, in these figures, white valves indicate an open state, and black valves indicate a closed state.

In Figure 5, ascitic organ / is / tube bundle! The bus-type condenser is equipped with a front water chamber λ and a rear water chamber 3, and the front ice chamber 2 is an inlet ice chamber separated by a partition plate. It is divided into a and an outlet ice chamber, 21). In addition, a plurality of cooling pipes arranged inside the condenser are connected to an inlet pipe bundle 'ja' which connects the inlet ice chamber 2a and the rear water chamber 3, and the rear water chamber 3.
and an outlet pipe bundle tb that connects the outlet water 54.2'D. A cooling water pipe 7 is connected to the discharge side of the water intake pump t, and a backwash valve is connected to the outlet end of the pipe via a stop valve g. This backwash valve valve and the inlet ice chamber 2a are connected by a water supply pipe 10, and
The backwash valve and the outlet ice chamber (2'l) are connected by a drainage pipe. Further, a drainage pipe /= is connected to the outlet port of the backwash valve, and the outlet end is led to the water discharge side, while a first valve 13 is installed on the pipe. The backwash valve has V boats, and the valve body is located at a position.

The flow path is switched according to ρ.

According to the invention, the rear water chamber 3 of the condenser/
A bypass pipe 5 is led out, and its pipe end is connected to the drainage pipe 1 on the downstream side of the first valve t3, and a second valve 6 is installed on the pipe.

Next, the operating procedure from forward washing to backwashing will be explained with reference to Fig. 5 to Fig. 1/7. Fig. 5 shows the state during normal washing, and Fig. 71 shows the state during backwashing. FIGS. z to 70 show states during transition.

/) During normal washing (g (see Figure 5) In this state, the stop valve and the first valve /3 are open, and the first valve /A is closed. Therefore, the cooling from the water intake pump B The cooling water introduced into the water pipe 7 is connected to the stop valve g,
It is introduced into the condenser/condenser through the backwash valve, the water supply pipe 10, the inlet ice chamber 2a, absorbs heat from the turbine exhaust gas flowing outside of it in the inlet tube bundle ja, passes through the rear water chamber 3, and enters the outlet tube bundle tb.
When flowing through the water, the water absorbs heat from the turbine exhaust again, and then is discharged into the sea via the extraction pipe, the backwash valve, the drain pipe 12, and the first valve/3.

2) During transition (states shown in FIGS. 2 to 70) First, the first valve /A is fully opened from the state shown in FIG. Then, the cooling water introduced into the rear water chamber 3 from the inlet pipe bundle ja is divided into parts, and a part of it is passed through the outlet pipe bundle 5'b to the drain pipe //, the backwash valve, and the first valve /3. Drainage pipe 1 via
The remaining part flows through the bypass pipe IS from the rear water chamber 3, and joins the flow in the drain pipe /2 through the first valve /6. During this time, a portion of the cooling water flows through the outlet tube bundle 5'l:lK, but all of the cooling water flows through the artificial tube bundle ja (see FIG. 2).

Next, change the valve body a of the backwash valve to its handle 5 and open the first valve 13.
fully close. Then, the cooling water that was introduced into the rear ice chamber 3 from the inlet pipe bundle 5a flows out from the bypass pipe 15, passes through the first valve 6, and is discharged into the drain pipe.
During this time, the amount of cooling water flowing through the outlet tube bundle, rb, becomes zero (see FIG. 7).

Next, when the valve body a of the backwash valve is switched to the neutral position as shown in Fig. is divided, flows in parallel in the water supply pipe 10 and the drainage pipe //, flows into the inlet ice chamber 2a and the outlet ice chamber 2b, flows in the direction of the arrow in the inlet pipe bundle ja and the outlet pipe bundle j'b, Rear water chamber 3
and flows out into the drainage pipe/2 via the bypass pipe/S and the second valve/6 (see Fig. g). In this state, 50% of the total amount of cooling water flows through each of the inlet tube bundle ta and the outlet tube bundle jb, and backwashing in the outlet tube bundle jb is started.

Next, turn the valve body 9a of the backwash valve clockwise! When the needles of the cooling water discharged from the water intake pump 2 are turned i'' and placed in the position shown in the figure, all the needles of the cooling water discharged from the water intake pump 2 are introduced into the outlet ice chamber 2b through the stop valve g, the backwash valve, and the drain pipe l/. The entire amount flows through the outlet pipe bundle jb in the backwashing direction, passes through the rear water chamber 3, the bypass pipe 15, and the first valve/6, and is discharged from the drain pipe tl (see Figure 3).

Furthermore, when only the downward valve 13 is fully opened from the state shown in FIG. Flow in the direction, inlet ice chamber, 2a, water supply pipe IO1 backwash valve, 1st
is discharged through the valve 13 and the drain pipe/2. In this state, although the flow meter decreases, the remaining cooling water flows through the bypass pipe 15 and is discharged from the drain pipe /U via the second valve /l (see Figure 1O).

Finally, when only the second valve/B is fully closed from the state shown in FIG. flows in the backwash direction inside the inlet pipe bundle ja, and the water supply pipe IO1 backwash square? ,
The water is drained through the first valve 13, Watosui Saichi/ko. In this state, all of the cooling water flows in the backwash direction within the inlet tube bundle ja and the outlet tube bundle jb (see Figure 1).

In addition, the valve operation from backwashing to forward washing can be performed by performing the above-mentioned operation in reverse, and the flow of cooling water is also the same.

In this way, except during the transient period shown in Fig. In this case, regular condensing performance will always be exhibited.

By the way, the vacuum of four water vessels (earth, soil,
Generally, the rated operation special clause is 7.20 WmHF! , is set and operated. On the other hand, trip signals in power plants due to less than the vacuum level of the condenser are generally OQOw, iHg
.

It is set around 100100 for rated operation.
It has a margin of more than t. Therefore, even if the condensing performance of the condenser temporarily decreases and the degree of vacuum of the condenser decreases, this does not pose a particular problem as long as the trip signal does not occur. According to performance studies, if half of the condenser tube bundle exhibits normal condensing performance for a short period of time during a backwash transient, normal operation of the power plant is possible due to the margin until the trip signal is generated. It is. In fact, in many power plants that have two pipe bundles and are equipped with backwash valves, the supply of cooling water to the condenser to one pipe bundle is temporarily stopped during a transient period of backwash operation. , the other one exhibits normal condensing performance, so it is operated without reducing the load on the power plant.

In the present invention, even when transitioning from forward washing to backwashing or from backwashing to normal washing, half of the tube bundles always exhibit normal condensing performance, so the transition can be made without reducing the load on the power plant. It becomes possible to do so.

Even in the broken state shown in Fig. g, the cooling water outlet of the entire water container is maintained as specified. At this time, the flow velocity in the cooling pipe is approximately half of the specified value. Generally, the condensing performance of a condenser is
It is known that it is proportional to the cooling area and proportional to the fourth power of the flow velocity in the cooling pipe. Therefore, the state shown in Fig. g is approximately 7.5% compared to the state in which half of the tube bundle is exhibiting normal condensing performance (for example, the state shown in Fig. 3). It can be seen that the condensation performance is j times higher. Therefore, even in the state shown in Fig. r, there is no need to change the load during a transient period.

In the above-described embodiment, the outlet side of the bypass pipe 15 was connected to the 1st water pipe % 12, but the bypass pipe 15 was directly led to the water discharge side and the No. 6 valve was installed on the pipe. It may be provided. In addition, stop valve r, first (D valve i
, 3. Each of the second valves/A is composed of an lenoid valve,
It can also be operated fully automatically using a sequential system @ VC.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, there is no need to reduce the load of the power generation plant during the transition from the forward washing state to the backwashing state or from the backwashing state to the normal washing state. The number of times is reduced, making continuous operation of the plant easier. Additionally, the thermal efficiency of the power plant throughout the year is increased, and the reliability of the power plant is improved, extending the plant life.

[Brief explanation of the drawing]

Figure 1 is a system diagram showing the cooling system of a conventional condenser.
Figure 3 is an explanatory diagram of the operation during backwashing, Figure 3 is an explanatory diagram showing the neutral position of the valve body of the backwash valve in a conventional condenser cooling system, and Figure 3 is the valve position and cooling of the backwash valve. A line diagram showing the relationship of water flow 1, Fig. 5 is a system diagram showing the state of the cooling system of the condenser according to the present invention during normal washing, and Figs. FIG. 1 is a system diagram showing a state during backwashing of the cooling system of a condenser according to the present invention. /... Condenser 1.2a... Inlet ice chamber, 2D/Outlet ice chamber, 3... Rear ice chamber, JA/Inlet tube bundle, JB/Outlet tube bundle, 2... Water intake pump, Ri/Backwash valve, 10. Water supply piping,
//・Water piping, /, 2-1゛Water piping, /3...1st
valve, 15. Baibanu piping, /6. Rabbit λ valve. Applicant's agent Kiyoshi Inomata 1st M Congee 2 Figure 3 Half 4 figures '$15 Figure 8 Figure 11

Claims (1)

[Claims] The cooling water introduced into the water supply piping from the water intake pump is guided through the inlet ice chamber to the inlet tube bundle of the condenser, and the cooling water flowing out from this inlet tube bundle is introduced into the outlet tube bundle through the rear ice chamber, and from this outlet tube bundle into the outlet water chamber. Outflowed cooling water is discharged through drainage piping/in the tube bundle Yupas condenser; the above water supply piping and drainage piping are connected by a backwash valve equipped with four boats, and the downstream side of this backwash valve is A first valve is installed in the drainage pipe-F, while a bypass pipe is led out from the rear ice chamber, and a second valve is installed on the pipe path of the bypass pipe, and its outlet end is guided to the water discharge side. Condenser cooling water system.