JPS6346387A - Condenser cooling water supplier - Google Patents

Abstract

PURPOSE:To reduce power for circulating water pumps (CWP) and to employ a steam turbine at a high efficiency by supplying cooling water in an optimum quantity in accordance with the operating conditions of steam turbines to respective condensers, in equipments for supply cooling water to a plurality of condensers using a common cooling water master pipe for a plurality of CWPs. CONSTITUTION:In equipments for supplying cooling water to a plurality of condensers 7, 10 and 13 by use of a common cooling water master pipe 6 by means of a plurality of moving-vane type circulating water pumps (CWP) 2 and 4, when the flow rate of cooling water is controlled to supply cooling water in an optimum quantity in accordance with the operating conditions of respective steam turbines 8, 11 and 14 on the basis of outputs 20, 23 and 26, a cooling water inlet temperature 17 and vacuum degrees 19, 22 and 25 and the like of the condensers, cooling water in an optimum quantity in accordance with the operating conditions of respective steam turbines is supplied to respective condensers 7, 10 and 13. Accordingly, it becomes possible to use a cooling water system including optimum CWPs 2 and 4 and cooling water blow rate adjusting valves 9, 12 and 15 in accordance with the operating conditions of respective steam turbines 9, 12 and 15.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention provides a condenser cooling water system that is improved to supply an optimum cooling water flow rate to a plurality of condensers in a steam turbine plant. Regarding the supply device.

(Prior art) In a steam turbine plant, there is equipment that supplies cooling water to multiple condensers using a common cooling water main pipe using one or more movable vane circulating water pumps (hereinafter abbreviated as CWP). 1. For example, FIG. 3 shows an installation having two movable airfoil CWPs, one common cooling water main pipe, a condenser, and three steam turbines.

In FIG. 3, seawater pumped up from the water intake 1 by movable vanes CWP2 and 4 having movable vanes 3 and 5, respectively, passes through a common cooling water main pipe 6, and passes through each condenser 7,
Supplied to 10.13. The cooling water supplied to each condenser 7, 10.13 is heat exchanged with the exhaust steam of each steam turbine 8.11.14, and the cooling water flow rate control valve 9.12.15
The water flows to the water outlet 16 via the water outlet. In addition, the common cooling water main pipe 6
There is a temperature detector 17 on the cooling water pipe of each condenser, a flow rate detector 18, 21.24 on the cooling water pipe of each condenser, and a vacuum degree detector 1 on each condenser.
9, 22.25 has been installed.

And each steam turbine 8, 11.14 has a generator 20, 2
3.26 is directly connected.

In this way, in the conventional system, each condenser 7°10, 1
The movable blade opening degree is controlled using only the total required flow rate of cooling water in step 3, and even though a flow rate detector 18°21.24 is attached, it is not used for control and is only used for general monitoring. The cooling water valves of each condenser 7, 10° 13 were used at a constant opening. The flow rate of cooling water flowing into the common cooling water main pipe 6 in this installation is adjusted by controlling the movable airfoils CWP2 and 4. The control system for these movable airfoils CWP2 and CWP4 is shown in FIG. In FIG. 4, the output of the generators 20, 23.26 directly connected to each steam turbine 8, 11.14 is input to an adder 27 and output as a total generator output. This total generator output and cooling water inlet temperature 17
is input to the function generator 28. The function generator 28 calculates the condenser 7, 10° 13 based on the generator output and the cooling water temperature.
Calculates and outputs the minimum flow rate required to obtain the optimal degree of vacuum.

The cooling water flow rate calculated by this function generator 28 and the CWP
The number of operating vehicles is input to the function generator 29.

The function generator 29 calculates and outputs the CWP movable blade opening degree based on the amount of cooling water calculated by the function generator 28 and the number Mo of operating CWPs required to secure this amount. In this case, the CWP system head is set to be constant. The movable blade opening calculated by the function generator 29 is input to the adder 30. Further, the adder 30 receives an advance signal SO for proactively securing the cooling water flow rate when the load of the steam turbine increases. The output of the adder 30 passes through a change rate limiter 31, an upper limit limiter 32, and is input to controllers 33 and 34 of each CWP movable blade, thereby controlling the movable blade opening degree of each CWP 2, 4. In addition,
Limit value CW of rate of change limiter 31 and upper/lower limit limiter 32
It is set based on the number of P's vehicles in operation.

However, in the above system, each steam turbine 8.11
．． There is no problem if the steam turbines 8, 14 are operating at the same load, but if the steam turbines 8, 11.14 are operating at different loads, each condenser 7, 1
Since the cooling water flow rate of 0.13 is evenly distributed, the following interlayer occurs. In other words, the condenser of a steam turbine operating at a high load will not be able to secure the necessary cooling water flow rate, and the condenser of a steam turbine operating at a low load will not be able to secure the required cooling water flow rate. Cooling water may be supplied. If the required cooling water flow rate cannot be secured,
The condenser vacuum is reduced and the steam turbine operates very inefficiently. Furthermore, supplying cooling water in excess of the required cooling water flow rate leads to a decrease in efficiency in terms of CWP operation.

An object of the present invention was to solve the above-mentioned problems in a steam turbine plant in which cooling water is supplied to a plurality of condensers using a common cooling water main pipe in one or more CWPs. An object of the present invention is to provide a condenser cooling water supply device that can reduce the power of CWP and operate a steam turbine with high efficiency.

[Structure of the invention]

(Means for Solving Problems) A condenser cooling water supply system for a steam turbine plant according to the present invention supplies cooling water to a plurality of condensers using a common cooling water main pipe by a plurality of CWPs. In the equipment that
CWP uses the vacuum degree of each condenser, the cooling water flow rate to each condenser, the output of each generator, and the cooling water temperature in the common cooling water main pipe to supply the optimal cooling water flow rate to each condenser. The invention is characterized in that it is configured to control the opening degrees of the cooling water flow rate control valves of the movable blades and the condenser.

(Function) In other words, a cooling water flow rate corresponding to the operating status of each steam turbine is supplied to each condenser based on the generator output, cooling water inlet temperature, and vacuum degree of the condenser, and at the same time, the required cooling of each condenser is The opening degree of the movable blades is controlled based on the maximum cooling water flow rate among the water flow rates and the number of CWPs in operation, so that the optimum amount of cooling water is obtained.

(Example) The present invention will be described below with reference to an example shown in FIGS. 1 and 2. The cooling water supply equipment for the condenser of the steam turbine plant to which the present invention is applied is the same as the system shown in FIG. 3, and the same parts are given the same reference numerals and the explanation thereof will be omitted. Furthermore, the present invention is characterized by an improvement in the control system for the cooling water supply equipment, and the same parts as those in the conventional system shown in FIG. 4 are given the same reference numerals and the explanation thereof will be omitted.

A first diagram showing a control system for a cooling water supply device according to the present invention.
In the figure, the cooling water flow rate control valves 9, 12, and 15 of each condenser 7, 10, and 13 shown in FIG.
, 4, and an opening control system for the movable blades 3 and 5 is arranged in each row. That is, each generator output 20° 23, 26 and cooling water inlet temperature 17 are the function generators 35, 45.5 of each column.
5, and each function generator 35, 45.55 calculates and outputs the cooling water flow rate required for each condenser 7, 10.13 based on these inputs.

On the other hand, each generator output 20, 23, 26 and cooling water inlet temperature 17 are input to the function generator 36, 46.56, and each function generator 36, 46.56 generates each output based on these inputs. Outputs the optimum degree of vacuum for condensers 7, 10, and 13. The values obtained by each of the function generators 36, 46.56 and the actual degree of vacuum 19, 22.25 of each condenser are input to the subtractor 37, 47.57.
．． From 57 onwards, the main focus is on the difference between the optimum degree of vacuum and the actual degree of vacuum. To prevent the control signal from being perturbed by condenser pressure fluctuations, this difference signal is passed through dead band circuits 38, 48, 58.
to the function generators 39, 49.59. The function generators 39, 49, 59 receive this difference signal and the cooling water inlet temperature 17 as inputs and output a correction signal for the required cooling water flow rate.

In the adders 40, 50, 60, the function generator 3
Each condenser 7,10.13 output from 5,45°55
Function generators 39, 49, 5 are used to determine the required cooling water flow rate for
9 and a preceding signal sO for ensuring the flow rate of cooling water in advance when the load of the steam turbines 8, 11.14 increases, and this output is sent to each condenser 7, 10.1.
This is the final required cooling water flow rate for 3. The difference between the value of the adder 40°50, 60 and the measured actual cooling water flow rate is output from the subtractor 41,51. ,52,
62 and the controller 44, 5 of each cooling water flow rate control valve 9° 12.15 via the upper limit limiter 43, 53, 63.
Sent on 4.64.

On the other hand, simultaneously with the operation of the valve opening control system for each cooling water flow rate control valve 9, 12, 15, the opening control system for the movable blades 3, 5 of the movable CWPs 2, 4 also starts operating. That is, the final required cooling water flow rate corrected by the adders 40, 50, and 60 of each control system is added by the adder 65 and becomes 3.
The total cooling water flow rate required for the two condensers 7, 10.13 is calculated. On the other hand, the high value selector 66 selects the maximum cooling water flow rate among the required cooling water flow rates for each condenser from the adders 40, 50, 60 of each control system, and outputs it to the function generator 67. This function generator 67 calculates the cwp required for the cooling water flow rate control valve opening degree of the control system selected by the high value selector 66 to be fully open based on the maximum cooling water flow rate selected by the high value selector 66. Outputs the total head.

The function generator 68 adds the CWP total head outputted from the function generator 67 to the total value signal of the cooling water flow rate required for the three condensers 7, 10.13 calculated by the adder 65 and the CWP. The CWP movable blade opening degree is calculated and output based on the number of operating vehicles Mo. The CWP movable blade opening degree calculated by the function generator 68 is input to the upper and lower limit limiter 70 via the rate of change limiter 69, and is input to the controller 71 of each CWP movable blade.
and 72, and the movable blade opening degree 3 of each CWP2 and 4 is inputted to
Control 5 with M. Note that the rate of change limiter 69. The upper and lower limit limiters and the limit values of 70 are set depending on the number of CWPs in operation.

In this way, in one embodiment shown in FIG.
In 2 and 4, a common cooling water main pipe 6 is used to connect multiple condensers 7,
In the equipment that supplies cooling water to 10.13, 9! Based on the electric machine output 20.23, 26, cooling water inlet temperature 17, and condenser vacuum degree 19, 22, 25, etc., determine the optimal cooling water flow rate according to the operating status of each steam turbine 8, 11.14. It controls the flow rate of cooling water to be supplied to each condenser, and each condenser 7, 10.13 has a steam turbine 8,
11. The optimum flow rate of cooling water according to the operating state of 14 will be supplied. Therefore, each steam turbine 8,1
It becomes possible to operate the cooling water system including the CWPs 2 and 4 and the cooling water flow rate control valve 9.12.15 in an optimal manner according to the operating state of 1.14.

Furthermore, the conventional control system shown in FIG.
Find the opening degree of the movable blades 3 and 5 of CWP2 and 4 from
The control system according to the embodiment of the present invention shown in FIG. This is a closed-loop control system in which the opening degree of each cooling water flow rate regulating valve 9, 12, and 15 is feedback-controlled using the total value. As a result, the control system of the present invention has superior features such as being able to perform more stable and better control than conventional control systems, and having less influence of disturbances entering the control system on control results. have

Next, in another embodiment of the present invention shown in FIG. 2, in order to preserve the environment at the site where a steam turbine plant is constructed,
It is agreed that the temperature difference between the inlet and outlet of the cooling water should be kept within 7 degrees Celsius. A device is added to correct the difference in outlet temperature to within 7°C.

That is, in FIG. 2, the difference between the outlet temperature and the inlet temperature of the cooling water is calculated by subtractors 72, 74.76 and input to function generators 73, 75.77. This function generator 73°7
5 and 77 output a signal for additively correcting the required flow rate of cooling water according to the temperature difference between the entrance and exit of the cooling water, and adders 40 and 5
Send to 0.60. In particular, when the temperature difference between the inlet and outlet of the cooling water exceeds 7°C, the function generators 73, 75, and 77 output a large value, increasing the required flow rate of the cooling water and increasing the flow rate of the cooling water, resulting in cooling. This controls the temperature difference between the water inlet and outlet to within 7°C.

Other cooling water flow control valves 9.12.15 and Cw
The operation and effect of the opening degree control system for the p movable blades 3 and 5 are the same as those in the embodiment shown in FIG. 1, and therefore the explanation thereof will be omitted.

〔Effect of the invention〕

As described above, in the present invention, in a facility that supplies cooling water to a plurality of condensers using a common cooling water main pipe in a plurality of CWPs, the optimum cooling water flow rate according to the operating state of each steam turbine can be determined. By configuring this to supply each condenser, it is possible to reduce the power of the CWP and operate the steam turbine with high efficiency.

[Brief explanation of the drawing]

Fig. 1 is a control system diagram showing one embodiment of a condenser cooling water supply system for a steam turbine plant according to the present invention, Fig. 2 is a control system diagram showing another embodiment of the present invention, and Fig. 3 is a conventional control system diagram. FIG. 4 is a system diagram showing a cooling water supply facility for a condenser, and FIG. 4 is a control system diagram showing a conventional cooling water flow rate control device. 2.4...Movable airfoil CWP 3.5-CWP(7) Possible a1 6...Common cooling water main pipe 7,10.13...
Condenser 8.11.14...Steam turbine 9.12.15...Condenser cooling water adjustment valve 17...Cooling water inlet temperature detector 18.21, 24...Cooling water flow rate detection Vessel 19.22,
25... Vacuum level detector 20.23.26... Generator 38.48, 58... Dead band circuit 66... High value selector 42.52, 62, 69... Change rate limiter 43 .53
, 63, 70... Upper and lower limit limiter agent patent attorney rules
Yudo Chika Hirofumi Mitsumata

Claims (2)

[Claims] (1) In a steam turbine plant where multiple movable vane circulating water pumps supply cooling water to multiple condensers using a common cooling water main pipe, the degree of vacuum of each condenser, The movable blades of the movable vane circulating water pump and each A condenser cooling water supply device characterized in that it is configured to control the opening degree of a cooling water flow rate control valve of a condenser. (2) In a steam turbine plant that supplies cooling water to multiple condensers using a common cooling water main pipe using multiple movable vane circulating water pumps, the cooling water flow rate required by each condenser is A condenser cooling system characterized in that the required head of the movable vane circulating water pump is determined using the maximum cooling water flow rate, and the movable vane opening of the movable vane circulating water pump is controlled. Water supply device.