JPH0663607B2 - Turbine plant with feedwater heater drain injection device - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a feedwater heater drain injection device for recovering the heat retained by a feedwater heater drain in a condensate system of a turbine plant to improve the thermal efficiency of the plant. The present invention relates to a turbine plant.

[Technical Background of the Invention and its Problems] As is well known, in a so-called regenerative cycle type turbine plant that heats condensed water or feed water sent to a reactor or a boiler by steam extracted from a steam turbine, a feed water heater is It is an indispensable device. In this feed water heater, in addition to the above-mentioned bleed air, a high-temperature fluid condensed by condensate or heat exchange with the feed water in the upper feed water heater, that is, a drain, is introduced to heat the condensate or feed water. Is configured to be sequentially heated by drain and steam. Condensed water or heating of the feed water by such a feed water heater is roughly divided into a high pressure system and a low pressure system according to the extracted steam pressure of the steam turbine, but the feed water heater drain of each system is heated at the last part of the system. When the collection was completed, the conventional method was to discard it in a condenser or the like. However, in recent years, it has been proposed that the drain of the feed water heater, which has completed this heat recovery, be recovered in a place other than the feed water heater, and it is attracting attention as a move to further improve the thermal efficiency. As an example of this technique, a case where it is applied to a low pressure system will be described with reference to FIG.

That is, the condensate system extracts condensate from the condenser 1 via the low-pressure condensate pump 2, purifies the condensate through the condensate purifier 3, and further boosts the pressure with the high-pressure condensate pump 4 to supply water heater (not shown). In this system, the feed water heater drain injection device 5, for example, the drain water heater 6 is extracted from the drain tank 6 via the drain pump 7 and is purified through the drain purification device 8. After that, it is a general configuration to provide a device for injection into the condensate system. In the figure, reference numeral 9 indicates a drain discharge pipe having a relief valve 10 for releasing the drain of the feed water heater to the condenser 1 in accordance with the abnormal stop of the drain pump 7, and reference numeral 11 indicates a control valve. From this, it is said that the drain of the feed water heater, which has been conventionally discarded in the condenser 1, is introduced into the condensate, so that the heat retained therein is given to the condensate and effective heat recovery can be achieved.

However, when the drain pump 7 is abnormally stopped, the feed water heater drain injection device 5 escapes the drain water heater 6 from the drain tank 6 to the condenser 1, so that when the turbine output is maintained, The amount of condensate that must be treated by the water-based condensate purification device 3 will significantly increase. Normally, the treatment capacity of the condensate purification device 3 is a substantially constant value per unit time, and an increase in the amount of condensate causes an immediate shortage of the capacity of the condensate purification device 3 and the quality of the condensate or feed water sent to the reactor etc. It will decrease. Especially in a nuclear turbine plant, water quality is strictly controlled in order to reduce the amount of substances activated in the nuclear reactor, and if the water quality cannot be reduced due to insufficient capacity of the condensate purification device 3, turbine output Will need to be restricted. Therefore, what can be considered to maintain the turbine output is to increase the capacity of the condensate purification device 3 that compensates for the insufficient capacity. But,
Since the capacity of the condensate purification device 3 is increased, abnormal stop of the drain pump 7 does not occur so frequently, so the increased capacity part is idle during normal times, which impairs economic efficiency. There is.

[Object of the Invention] An object of the present invention is to provide a feed water heater drain injection device capable of maintaining the turbine output at the time of abnormal stop of the drain pump, while at the same time preventing the condensate or the quality of the feed water from deteriorating. It is to provide a turbine plant having.

[Summary of the Invention] The present invention collects a drain generated by heat exchange with condensate in a low-pressure feed water heater into a drain tank, injects the drain into condensate flowing through a condensate system through a drain pump, and drains the drain. In a turbine plant having a feed water heater drain configured to escape the drain from the drain tank to the condenser in accordance with the abnormal stop of the pump, in the condensate system, branched from the upstream side of the condensate purification apparatus, First and second bypass pipes each having a first and a second condensate stop valve, which reach the downstream side of the condensate purification device, are provided, and an emergency condensate purification is provided in the path of the first bypass pipe. The device is arranged so that when the drain pump stops abnormally,
It is characterized in that almost all the increasing condensate water is purified through an emergency purifying device, and the remaining part of the condensate water is directly introduced into the condensate water without being purified.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIG.
In addition, the same reference numerals are given to the portions shown in FIG. 2 in the drawing, and the description thereof will be omitted.

In FIG. 1, the present invention relates to first and second bypass pipes 12 that connect the upstream side and the downstream side of the condensate purification device 3, respectively.
An emergency condensate purification device 14 and a first condensate stop valve 15 are provided in the path of the first bypass pipe 12, and a second condensate stop valve 15 is provided in the second bypass pipe 12.
The second condensate stop valves 16 are arranged in the respective paths of the bypass pipes 13. Further, a flow meter 17 for detecting the condensate flow rate is provided on the downstream side of the condensate purification device 3. In addition to these, the present invention is provided with the control devices 18 and 19 constituting the control part as follows. That is, when the stop signal of the drain pump 7 is input, the control device 18 transmits the stop signal to the relief valve 10 and the control valve 11 to change the valve opening degrees thereof. At the same time, this signal is also transmitted to the standby unit of the low-pressure condensate pump 2 and the first condensate stop valve 15, respectively, so that the standby unit is started and the valve opening degree of the first condensate stop valve 15 is set to the fully open position. It is something to do. On the other hand, the control device 19 sets the valve opening degree of the second condensate stop valve 16 to the fully open position when the condensate flow rate detected by the flow meter 17 exceeds a predetermined value.

The present invention has the above-described structure, and when one of the drain pumps 7 is abnormally stopped, a signal for opening the relief valve 10 is issued, and a part of the water supply heater drain from the drain tank 6 is condensed. 1 to prevent the water level in the drain tank 6 from rising. At this time, at the same time, the valve opening of the control valve 11 is throttled to reduce the drainage of the feed water heater flowing to the condensate system, and the condensate amount also decreases accordingly. However, the stop signal of the drain pump 7 causes the low pressure condensate pump 2 A signal is issued to activate the standby machine of the above, and the amount of condensate required to maintain the turbine output is secured. Although the capacity of the condensate purification device 3 becomes insufficient due to the increase of the amount of condensate passing through the condensate system, the low pressure condensate pump 2
At the same time that the standby machine is started up, a signal to open the condensate stop valve 15 provided in the first bypass pipe 12 is also issued, so a part of the condensate is guided to the emergency condensate purification device 14, Here, the water is purified and sent again into the condensate on the downstream side of the condensate purification device 3. As a result, even if the capacity of the condensate purification device 3 is the same as the conventional one, there is no hindrance in maintaining the turbine output, while the condensate is purified by the emergency purification device 14, so there is no concern that the water quality will deteriorate. . The capacity of the emergency purification device 14 is determined in consideration of the discharge amount of one drain pump 7, but it is not necessary to make the capacity so large. To this end, the flow rate after the condensate is merged on the downstream side of the condensate purifier 3 is monitored by the flow meter 17, and even if the condensate purifier 3 and the emergency purifier 14 are combined in terms of capacity. If not enough, use condensate that does not purify only the shortage to suppress capacity increase. That is, when the condensate flow rate exceeds a predetermined value, a signal for opening the second condensate stop valve 16 provided in the second bypass pipe 13 is issued, so that condensate purification is performed. A minimum amount of condensate flow is formed that bypasses both the device 3 and the emergency condensate purification device 14, thereby always ensuring the required amount of condensate.

[Effects of the Invention] As described above, the present invention includes the first and second condensate stop valves that branch from the upstream side of the condensate purification device in the condensate system and reach the downstream side of the condensate purification device. Since the first and second bypass pipes are provided, and the emergency condensate purification device is arranged in the path of the first bypass pipe, it is possible to maintain the turbine output when the drain pump is abnormally stopped. It has an excellent effect that it is possible to prevent deterioration of the water quality of the supplied water.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of a turbine plant of a feed water heater drain injection device according to the present invention, and FIG. 2 is a system diagram showing an example of a turbine plant having a feed water heater drain injection device of the prior art. . 1 …… Condenser 3 …… Condensate Purifier 5 …… Supply Heater Drain Injector 6 …… Drain Tank 7 …… Drain Pump 8 …… Drain Purifier 10 …… Relief Valve 12 …… First Bypass Pipe 13 …… Second bypass pipe 14 …… Emergency condensate purification device 15 …… First condensate stop valve 16 …… Second condensate stop valve 17 …… Flowmeter 18, 19 …… Control device

Claims (1)

[Claims] 1. A drain tank collects drain generated by heat exchange with condensate by a low-pressure feed water heater, and injects the drain into condensate flowing through a condensate system through a drain pump.
In a turbine plant having a feed water heater drain injection device configured to allow drain to escape from the drain tank to a condenser in accordance with an abnormal stop of the drain pump, branch from the upstream side of the condensate purification device in the condensate system. First and second bypass pipes having first and second condensate stop valves, respectively, which reach the downstream side of the condensate purification device, are provided, and the emergency passage is provided in the path of the first bypass pipe. A condensate purification device is installed so that when an abnormal stop of the drain pump occurs, almost all of the increasing condensate is purified through the emergency condensate purification, and the remaining part of the condensate is not treated as it is. A turbine plant having a feed water heater drain injection device characterized by being introduced into water.