JPS5918214A - Power plant using extraction turbine - Google Patents

Abstract

PURPOSE:To improve the collection of heat from a return drain by a method wherein the return drain from a water producing plant annexed to the titled power plant is made to be supplied to a low pressure condensing system or a deaerator through a pipe according to the load condition of the turbine. CONSTITUTION:When the power plant is operated in a high load condition, a motor-driven stop valve 23 and a bypass valve 18 are closed and the return drain from an auxiliary steam pipe 22 for the deaerator led from the water producing plant 5 is flowed to the outlet port of a low pressure feed water heater 8 from a drain pipe 13 through a stop valve 14 without using the drain. Further, condensed water is supplied to a boiler 3 through a low pressure feed water heater 9, the deaerator 10 and a high pressure feed water heater 12. On the other hand, when the power plant is operated in a low load condition, the bypass valve 18 is opened and stop valves 16 and 17 are closed so as to collect the return drain from the water producing plant 5. Then, when the temperature of the condensed water bypassed the feed water heater 9 rises higher than a predetermined value, the stop valve 14 is closed and the stop valve 23 is opened so as to supply the return drain to the deaerator 10 from the auxiliary steam pipe 22.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a large-capacity extraction turbine power generation plant equipped with a water supply plant.

[Technical background of the invention and its problems]

In factories that require power and working steam, extraction turbines are used when the amount of steam is relatively small compared to the power, or when the fluctuations in the amount are significant. In this case, a portion of the inlet steam is extracted midway for work use, and the remaining steam flows into the condenser. In addition, the large-capacity extraction turbine power generation plant is equipped with a water supply plant that uses the extracted air from the turbine for water treatment, and the return drain from this water supply plant is collected into the low-pressure water line for heat recovery.

However, in an extraction turbine power generation plant, due to the necessity of installing a water production plant in parallel, it is not possible to reduce the oil and gas on the water supply plant side even if the turbine output is reduced to a partial load. As the load increases, the pressure of the heating steam for the low-pressure feedwater heater and deaerator decreases. , C: The temperature of the collected condensate returned from the water supply plant may become inversely l2 higher than the internal saturation temperature of the low-pressure feed water heater.

Normally, when operating a turbine, if it is desired to further reduce the output, this may be done by performing a cut operation that excludes the low-pressure feedwater heater. However, if the minimum load required by the turbine output is lower, the saturation temperature inside the deaerator will be lower than the condensate collected in the return drain of the desalination plant; Operation cannot be considered from the viewpoint of plant operation. Therefore, it is conceivable to use a degassing device that uses high-pressure heated steam from the turbine's pressure equipment as a backup, but this is not an effective countermeasure because it also worsens the heat rate of the turbine plant.

There is also a method of moving the extraction point for heating steam to the deaerator to the high-pressure side during basic turbine design to obtain higher extraction pressure even at partial load, but in terms of optimal design of the turbine plant, it is difficult to This is not necessarily an effective measure as it may worsen the heat rate. For this reason, there is a problem in that the operating range of a large-capacity extraction turbine power plant depends not only on the final stage exhaust temperature but also on the saturation temperature of the deaerator.

[Purpose of the invention]

An object of the present invention is to provide an extraction turbine power generation plant that effectively recovers heat from return drain from the water production plant in an extraction turbine plant that is attached to a water production plant, and that is not subject to restrictions on the operating range of the turbine power generation plant. There is something to do.

[Summary of the invention]

The present invention relates to an extraction turbine power generation plant characterized in that return drain from an attached water supply plant is used as auxiliary steam for a deaerator.

[Embodiments of the invention]

The present invention will be described below with reference to embodiments shown in the drawings. Does the drawing show the control of the degassing device of the present invention? 1 shows an overall system diagram of an extraction turbine power generation plant using an Ml device. Extraction turbine power generation plants can be broadly classified into steam turbine systems 1. Generator that will be driven 2. A boiler 3 that supplies steam to the steam turbine 1. The extraction turbine power generation plant, which is comprised of a steam turbine 1 and a bale water generator 4, and which is the object of the present invention, is also equipped with a water production plant 5 that utilizes the extraction air of the steam turbine 1.

That is, the steam of the boiler 3 is guided through the live steam pipe 6 to the high pressure turbine IT and the low pressure turbine IL, where it performs work and drives the generator 2. The steam that has worked in the turbine 1 is condensed in the condenser 4, and is degassed by the condensate pump 7 (heated through the first-stage low-pressure feedwater heater 8 and second-stage low-pressure feedwater heater 9). It enters the equipment 1tlO, where it is deaerated and heated by the steam extracted from the turbine, and then the pressure is increased by the boiler feed water pump 11 and sent to the boiler 3 via the high pressure feed water heater 12.
The return drain is collected from the drain pipe 13 to the outlet of the low pressure feed water heater 8 via the electric stop valve 14 and the check valve 15. It is controlled by the steam turbine internal control system and is open during normal high-load operation of the steam turbine. The second stage low pressure feed water heater 9 is provided with a stop valve +6.17 on both sides thereof, and a heater bypass valve 1
There are 8.

The extracted steam from the deaerator 10 and the high-pressure turbine IT is supplied from the bleed pipe 19 through the electric stop valve 20 and the check valve 2, and this extracted steam causes the condensate inside the deaerator filO to be is degassed and heated. Electric, stop valve 20Fi
It is kept open under normal high load conditions by a control device to be described later. In addition, for the deaeration rod (2), the auxiliary steam pipe 22 that leads the return drain of the desalination plant 5 is branched, and the electric stop valve 23,
The steam is returned via the check valve 24 and the flash tank 25 and is led as auxiliary steam.

The electric stop valve 23 is closed under normal high load conditions by a control device to be described later. Exposure deaerator 10 and condenser 4
or between the first stage low pressure feed water heater 8 and the internal pressure adjustment%l
26 is provided, and its electric stop valve 27 is controlled by a control device to be described later. The drain in the flash tank 25 is controlled by a drain level control device 28 and a drain level adjustment valve 29, and the excess drain is transferred to the drain pipe 3.
At 0, it is sent to the condenser and its level is controlled.

Now, the deaerator internal pressure control device 31 that controls the electric stop valves 14, 2 (1, 23, 27) has an orifice: 32 that controls the flow of waste water from the low-pressure feed water heater 9 to the deaerator 10.
The flow rate detector 33 detects this and inputs it as a flow rate signal, and the submerged water temperature signal detected by the condensate temperature detector 34 is input. Further, the pressure inside the deaerator 10, which is one input of the control device 431, is detected by the detector 35 and is inputted as an inside pressure signal. Sara(
- The flow t of the return drain separated by the auxiliary steam pipe 22 of the water supply plant 5 is detected by the orifice 36 and the detection 537, and is output as a flow rate signal by the control device 17: (11), and the temperature of this return drain is , and is detected by a detector 38 and inputted as a return drain temperature signal.

Next, the operation of the control device for the deaerator 10 of the present invention will be explained. The plant system diagram in the cutout drawing shows the heavy load operation of the extraction turbine power generation plant, and the electric cutoffs are stopped by commands from the deaerator internal pressure control device 18.
27 it is open, and the electric stop valves 2 and 3 and the bypass valve 18 are closed. However, the return drain C2 from the auxiliary steam pipe 22 for the deaerator from the fresh water production plant 5 was not used. In this state, the drain to be returned to the desalination plant 5 or drain new 1.3 to i, 1ltll stop valve 1
4 and a check valve 15 to join the outlet of the low pressure feed water heater 8. This condensate is heated by the low pressure feed water heater 9, degassed by the deaerator 1, heated by turbine bleed steam entering from the bleed pipe 19, and then passed through the high pressure feed water heater 12 to the boiler 3. sent to.

Now, when the extraction turbine power generation plant becomes a low load, the bypass valve 18 is opened, the stop valve 1h is closed, and the stop valve 1.7 is closed. The temperature of the condensate recovered in step 5 and bypassed the low-pressure feed water heater 9 is determined by the temperature of the condensate that is
When the temperature difference inside the vessel becomes crystalline, the electric stop valve 14 located at the drain pipe 1:3 of the water supply plant 5 is closed by a signal from the deaerator internal pressure control device 31, and the drain pipe 13 is closed. The electric stop valve 23 in the auxiliary steam pipe 22 branched from the auxiliary steam pipe 22 is opened, and the electric stop valve 20 in the extraction steam pipe 19+2 is closed.

The collection of the return drain from the water production plant 5 to the condensate system, which had been completely drained, and the supply of extracted steam from the sieving turbine IT to the deaerator ffff1lU were stopped, and the return drain from the water production plant 5 was stopped. Deaerator 1 following auxiliary steam pipe 22
It will be supplied to 0.

The return drain of the desalination plant 5 of the auxiliary steam tank 22 is 'F
IL 4n stop valve 13. Continuation valve 24 and orifice;
31) It passes through a groove and enters the flattening tank 2b, where it becomes flash steam, becomes steam for degassing and heating, and enters the deaerator F<HJ. During this time, the return drain flow M is detected by the detector 37 tL, and the temperature is detected by the M degree detector 38.

That is input to the first control device; Further, the condensate that enters the deaerator after passing through the low-pressure feed water heater 8 is detected by a flow rate detector 33 and a tLm:detector 34, respectively, for flow tt and temperature, and is manually input to a control device 31. .

The internal pressure of the deaerator υ1131 is manually controlled by the pressure detector 35 and the control device 311. The deaerator internal pressure control device 31 receives these signals, and the internal pressure for the deaerator is controlled by the drain and low-pressure condensate returned from the water supply plant 5.
! - Each detector 37, 38, 33, 34, 3
The input signal from step 5 is operated and the pressure regulating valve 27 is adjusted based on the result from step 7. This pressure regulating valve 2: (by means of the deaeration system, the inside of the IO is reversely connected to the one-layer water heater 4 or the first low-pressure water heater 8 through the pipe 26, and the inside of the deaeration gliT 10 is reduced to a low pressure. 6) By adjusting the pressure so that the saturated pressure is slightly lower than the saturated pressure after mixing the water and desalination return drain, flash steam C is generated in the water return drain C flash tank 25.
This makes it possible to use the degassing steam for the degassing device. At that time, the drain in the flash tank 25 is controlled by the drain level control device 28 and the regulating valve 29. It is sent to the condenser 4 as surplus drain.

〔Effect of the invention〕

As described above, according to the present invention (2), in an extraction turbine power generation plant with a water production plant attached, the return condensate from the water supply plant can be used as heating steam for deaeration in the deaerator even during low load. It has the advantage of improving heat recovery and expanding the operating range of the steam turbine without the need to limit the load on the water supply plant. 1 is a new diagram of a steam system showing an embodiment of a 1;1 turbine-generated 17. plant of the present invention.

1...Extraction steam turbine JT...High pressure turbine I
L...Low pressure turbine 2...Generator 3...Hoiler
4...I υ Water vessel 5 ・zu. water plant 8.9
...Low pressure feed water heater 1 (]...Deaeration t''-direct
1 heat...Commercial Fhi water supply heating;, 41.1...4 Water plant return drain pipe 14, 20. Niji: (,27・
・Electric+M stop valve 1b, 11...stop valve 1B・
...Bypass valve 22...Auxiliary steam 21)...
Flash tank: 31... Deaeration equipment internal pressure control device 3'/:, 3t Bi... Orifice 3: l +; 37
...Flow iif'tφ output device: 3<, 3s...Temperature 11
1- Chivalry device

Claims (1)

[Claims] (1) A plan in which a generator is driven by an extraction turbine that extracts steam from an intermediate stage) A low-pressure condensate system G2 is mixed depending on the load condition of the return drain turbine of the attached water production plant. An extraction turbine power generation plant characterized by having 11 piping configurations so that it can be supplied as auxiliary steam to a deaerator (2) Return drain from a water production plant is mixed with condensate at the outlet of a low-pressure feedwater heater when the turbine is under high load. The extraction turbine according to claim 1, wherein the extraction turbine is used as auxiliary steam for the deaerator when the condensate temperature evolution under low load becomes higher than the internal saturation temperature of the deaerator. power plant