JP2007292414A - Combined cycle power generation facility and water quality management method for combined cycle power generation facility - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a combined cycle power generation facility and a water quality management method for maintaining the chemical concentration of a low pressure water supply system always to an appropriate value. <P>SOLUTION: In this supply water treatment method, a pH conditioner and an oxygen scavenger are directly injected into a low pressure drum 25 to control the water quality of supply water supplied into the low pressure drum 25 from a steam turbine plant through a condensate supply pipe 32. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention maintains a water supply adjusting agent such as a pH adjusting agent and an oxygen scavenger injected into the water supply of an exhaust heat recovery boiler of a combined cycle power generation facility at an appropriate management value, and prevents corrosion of plant components. The present invention relates to a combined cycle power generation facility having means and a water quality management method for the combined cycle power generation facility.

  Conventionally, in an exhaust heat recovery boiler applied to a thermal power plant, for example, a combined cycle power plant, a limit value is provided for the dissolved oxygen concentration and pH value in the feed water, and water quality management is performed so as to maintain this limit value or less. Prevents corrosion of components.

  Of these water quality management of dissolved oxygen and pH, in order to maintain the dissolved oxygen concentration below the limit value, an oxygen scavenger such as hydrazine is injected into the low-pressure water supply system of the exhaust heat recovery boiler and dissolved in the water supply. The chemical reaction with oxygen kept the concentration low.

  Moreover, about pH value, the pH adjuster which made ammonia the mainstream was inject | poured into the low voltage | pressure water supply system like the deoxidizer, and pH value was adjusted.

  In addition, water quality control in the drum of the exhaust heat recovery boiler is injecting sodium phosphate as a cleansing agent into the can water, reducing the hardness of the can water, and adjusting the pH value of the can water.

  However, the sodium phosphate that can be injected as a cleansing agent for can water is up to the high-pressure drum and medium-pressure drum of the exhaust heat recovery boiler, and has not been injected into the low-pressure drum can water. The reason for not injecting sodium phosphate into the low pressure drum water is as follows.

  Sodium phosphate is originally a non-volatile substance that reacts with minerals in canned water to produce deposits.

  For this reason, the can water discharged from the low-pressure drum has a route that flows to the steam turbine through a heat exchanger for medium pressure and high pressure, and a route that flows directly to the steam turbine through a temperature reducer. If the deposits flow into the steam turbine, the steam flow will be affected by the deposits, resulting in damage to the heat exchanger tubes of the heat exchanger and reduced efficiency of the steam turbine. .

  From such an event, in the low pressure drum of the exhaust heat recovery boiler, hydrazine having high volatility has been conventionally used as an oxygen scavenger, and ammonia has been exclusively used as a pH adjuster.

Patent Literature 1, Patent Literature 2 and the like are disclosed as technologies using ammonia, hydrazine or the like for water quality adjustment of a thermal power plant.
JP 2002-180804 A JP-A-2005-313116

  Based on the above situation, the low-pressure drum of the exhaust heat recovery boiler relied solely on water quality management with volatile substances such as ammonia and hydrazine, but there are several problems with volatile substances. There is also corrosion and thinning of components due to ammonia.

  That is, the steam emitted from the low-pressure drum of the exhaust heat recovery boiler reaches the steam turbine through a number of heat exchangers along with the volatile substances. In this case, the chemical concentration in the steam is higher than the chemical concentration of water due to the characteristics of the chemical. In particular, the ammonia concentration is closely related to pH, and if the operation is continued for a long period of time while the pH value exceeds the limit value, it is called a so-called ammonia attack, which causes corrosion and thinning of the component equipment. It was.

  For this reason, it is necessary to sufficiently manage the water quality without exceeding the limit value of the ammonia concentration contained in the water supply.

  The present invention has been made in consideration of such circumstances, and combined cycle power generation equipment and combined cycle power generation equipment that can always maintain the chemical concentration of the low-pressure water supply system at an appropriate value without greatly changing the piping system. The purpose is to provide water quality management methods.

  In order to achieve the above object, a combined cycle power generation facility according to the present invention includes a low-pressure steam turbine, a condensate water supply pipe for supplying condensate condensed with exhaust steam of the low-pressure steam turbine to a low-pressure drum, and a pump. A combined cycle power generation facility connected to the condensate water supply pipe and having a chemical injection system for injecting a pH adjusting agent and a deoxygenating agent for water quality management into the condensate, directly to the low pressure drum, or An injection port for injecting a pH adjusting agent and a deoxygenating agent for water quality management is provided in any one of the pipes connected to the low-pressure drum.

  In addition, the water quality management method for the combined cycle power generation facility according to the present invention adds the pH adjuster and the oxygen scavenger to the condensate condensed with the exhaust steam of the low-pressure steam turbine in order to achieve the above-mentioned purpose. When performing, in addition to injecting through the chemical injection system provided in the condensate water supply pipe for supplying the condensate from the low-pressure turbine to the low-pressure drum, piping connected directly to the low-pressure drum or to the low-pressure drum The pH adjusting agent and the oxygen scavenger are injected from an injection port provided at any one of the above.

  The combined cycle power generation facility according to the present invention, when adjusting the quality of the feed water supplied from the steam turbine plant to the low pressure drum via the condensate feed water pipe, in addition to the condensate feed pipe, directly to the low pressure drum or to the low pressure drum. Since the pH adjuster and oxygen scavenger are injected into any one of the connected pipes, even highly volatile pH adjusters and oxygen scavengers can always be replenished, and the water quality concentration can be increased. It can be maintained at an appropriate value at all times to suppress the corrosion of the system and components, and to make the plant operate stably.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of a combined cycle power generation facility and a water quality management method for a combined cycle power generation facility according to the present invention will be described with reference to the drawings and reference numerals attached to the drawings.

  FIG. 1 is a schematic system diagram of a combined cycle power plant according to the present invention.

  In this combined cycle power plant, the gas turbine plant 1 and the steam turbine plant 2 are coupled by a common rotating shaft 3, and the exhaust heat recovery boiler 4 is disposed separately.

  The gas turbine plant 1 includes an air compressor 6, a combustor 7, and a gas turbine 8. The atmosphere AR sucked by the air compressor 6 is converted into high-pressure compressed air and guided to the combustor 7, where fuel F is added. Combustion gas is generated, the combustion gas is expanded by the gas turbine 8, and the generator 5 connected coaxially is driven by the power generated at that time.

  The steam turbine plant 2 includes a high-pressure turbine 9, an intermediate-pressure turbine 10, a low-pressure turbine 11, and a condenser 12, and guides the exhaust steam expanded by the high-pressure turbine 9 to the reheater 13 of the exhaust heat recovery boiler 4. Then, it is guided to the intermediate pressure turbine 10 and expanded as reheated steam, and the exhaust steam is expanded again by the low-pressure turbine 11, and then condensed into condensate by the condenser 12, and supplied as water via the pump 13 a. To the exhaust heat recovery boiler 4.

  On the other hand, the exhaust heat recovery boiler 4 has a first high pressure superheater 14, a reheater 13, and a second high pressure superheater 15 in order from the upstream side to the downstream side along the flow of the exhaust gas G of the gas turbine plant 1. A third high-pressure superheater 16, a high-pressure evaporator 18 with a high-pressure drum 17, an intermediate-pressure superheater 19, a high-pressure economizer 20, a low-pressure superheater 21, an intermediate-pressure evaporator 23 with an intermediate-pressure drum 22, A pressure-saving economizer 24, a low-pressure evaporator 26 having a low-pressure drum 25, and a low-pressure economizer 27 are accommodated, and steam is generated by heat exchange between each heat exchanger and the exhaust gas G.

  Further, the exhaust heat recovery boiler 4 preheats the condensate / feed water supplied from the condenser 12 of the steam turbine plant 2 via the pump 13a by the low pressure economizer 27 and guides it to the low pressure drum 25, where Using the density difference of the can water, it is circulated to the low-pressure evaporator 26 to generate steam, and this steam is supplied to the low-pressure turbine 11 via the low-pressure superheater 21.

  Further, the low pressure economizer 27 is diverted on the outlet side, and a part thereof is guided to the intermediate pressure drum 22 via the low pressure pump 28 and the intermediate pressure economizer 24, and again using the density difference of the can water. The steam is circulated through the intermediate pressure evaporator 23 to generate steam, and this steam is supplied to the low-temperature reheat pipe 28 a through the intermediate pressure superheater 19.

  The low temperature reheat pipe 28a guides the exhaust heat steam from the high pressure turbine 9 and the steam from the intermediate pressure superheater 19 to the reheater desuperheater 30 via the second high pressure superheater 15, where Water is sprayed to reduce the temperature of the reheated steam and is supplied to the reheater 13.

  Further, the low pressure economizer 27 guides the remainder branched on the outlet side to the high pressure drum 17 via the high pressure pump 29 and the high pressure economizer 20, and circulates the high pressure evaporator 18 to generate steam. This steam is guided to the third high pressure superheater 16.

  The third high-pressure superheater 16 includes a high-pressure superheater desuperheater 31, sprays the feed water from the high-pressure pump 29 to reduce the temperature of the superheated steam, and the steam turbine plant 2 via the first high-pressure superheater 14. To the high-pressure turbine 9.

  Further, a pH adjusting agent injection pump 33 for injecting a pH adjusting agent as a chemical injection system into a condensate water supply pipe 32 connecting the condenser 12 of the steam turbine plant 2 and the low pressure economizer 27 of the exhaust heat recovery boiler 4. And the sodium phosphate injection pump 34 for injecting sodium phosphate, the chemical is injected into the condensate water supply.

  Each of the high-pressure drum 17 and the intermediate-pressure drum 22 is provided with a high-pressure drum sodium phosphate injection pump 35 for injecting sodium phosphate and an intermediate-pressure drum sodium phosphate injection pump 36, respectively.

  In the combined cycle power generation having such a configuration, in the present embodiment, as shown in FIG. 2, each of the pH adjuster (ammonia) and the oxygen scavenger (hydrazine) is directly applied to the low pressure drum 25 of the exhaust heat recovery boiler 4. A pH adjusting agent inlet 37 and an oxygen scavenger inlet 38 for injection are provided. Each of the pH adjusting agent inlet 37 and the oxygen scavenger inlet 38 is provided with a pump (not shown).

  As described above, in this embodiment, since the pH adjusting agent and the oxygen scavenger are directly injected into the low-pressure drum 25 and the means for supplementing the highly volatile chemical is taken, the water quality management of the supplied water is maintained by maintaining the proper concentration. Well done.

  In this embodiment, the pH adjusting agent and the oxygen scavenger are directly injected into the low pressure drum 25. However, the present invention is not limited to this example, and the low pressure drum 25 and the low pressure evaporator 26 are connected as shown in FIG. A pH adjusting agent inlet 37 and an oxygen scavenger inlet 38 may be provided in the downcomer 40, respectively, and the pH adjusting agent and the oxygen absorber may be injected using the pumping force of a pump (not shown). As shown in FIG. 4, a pH adjusting agent inlet 37 and a deoxygenating agent inlet 38 are respectively provided in the medium and high pressure water supply pipe 41 connecting the low pressure drum 25, the intermediate pressure pump 28 and the high pressure pump 29, and the pump pressure is utilized. Then, a pH adjuster and an oxygen scavenger may be injected.

  Further, in the present embodiment, as shown in FIG. 5, a deaerator 42 is provided at an intermediate position connecting the low pressure economizer 27 and the low pressure drum 25, and the pH adjusting agent inlet 37 and the deoxygenation are provided in the low pressure drum 25. A pH adjusting agent and a deoxygenating agent may be introduced by using a pumping force provided with an agent injection port 38, and the pH adjusting agent between the low pressure drum 25 and the deaerator 42 as shown in FIG. An inlet 37 and an oxygen scavenger inlet 38 may be provided, and the pH adjusting agent and the oxygen scavenger may be injected into each by utilizing the pumping force of the pump. As shown in FIG. A pH adjusting agent inlet 37 and an oxygen scavenger inlet 38 are provided in the downcomer 40 connecting the vaporizer 42 and the low pressure evaporator 26, and a pH adjusting agent and an oxygen scavenger are injected into each by using the pumping force of the pump. As shown in FIG. Even if a pH adjusting agent inlet 37 and an oxygen scavenger inlet 38 are provided in the medium-high pressure water supply pipe 41 connected to the deaerator 42 and the pH adjusting agent and the oxygen scavenger are injected into each by using the pumping force of the pump. Good.

BRIEF DESCRIPTION OF THE DRAWINGS The whole schematic system diagram of the combined cycle power plant incorporating the water supply processing method and water supply processing apparatus which concern on this invention. The partial schematic system diagram of the combined cycle power generation equipment which shows 1st Embodiment incorporating the water quality management method and water quality management apparatus which concern on this invention. The partial schematic system diagram of the combined cycle power generation equipment which shows 2nd Embodiment incorporating the water quality management method and water quality management apparatus which concern on this invention. The partial schematic system diagram of the combined cycle power generation equipment which shows 3rd Embodiment incorporating the water quality management method and water quality management apparatus which concern on this invention. The partial schematic system diagram of the combined cycle power generation equipment which shows 4th Embodiment incorporating the water quality management method and water quality management apparatus which concern on this invention. The partial schematic system diagram of the combined cycle power generation equipment which shows 5th Embodiment incorporating the water quality management method and water quality management apparatus which concern on this invention. The partial schematic system diagram of the combined cycle power generation equipment which shows 6th Embodiment incorporating the water quality management method and water quality management apparatus which concern on this invention. The partial schematic system diagram of the combined cycle power generation equipment which shows 7th Embodiment incorporating the water quality management method and water quality management apparatus which concern on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas turbine plant 2 Steam turbine plant 3 Rotating shaft 4 Waste heat recovery boiler 5 Generator 6 Air compressor 7 Combustor 8 Gas turbine 9 High pressure turbine 10 Medium pressure turbine 11 Low pressure turbine 12 Condenser 13 Reheater 13a Pump 14 First high pressure superheater 15 Second high pressure superheater 16 Third high pressure superheater 17 High pressure drum 18 High pressure evaporator 19 Medium pressure superheater 20 High pressure economizer 21 Low pressure superheater 22 Medium pressure drum 23 Medium pressure evaporator 24 Medium joint Charcoal unit 25 Low pressure drum 26 Low pressure evaporator 27 Low pressure economizer 28 Low pressure pump 28a Low temperature reheat pipe 29 High pressure pump 30 Reheater temperature reducer 31 High pressure superheater temperature reducer 32 Condensate feed pipe 33 pH adjuster injection pump 34 Sodium phosphate injection pump 35 High pressure drum sodium phosphate injection pump 36 Medium pressure drum sodium phosphate injection pump 37 pH adjuster injection port 38 Deoxygenation Agent inlet 39 Pump 40 Precipitation pipe 41 Medium-high pressure water supply pipe 42 Deaerator

Claims (10)

A low pressure steam turbine;
A condensate water supply pipe for supplying condensate condensed with the exhaust steam of the low-pressure steam turbine to the low-pressure drum;
A chemical injection system that is connected to the condensate water supply pipe via a pump and injects a pH adjusting agent and an oxygen scavenger for water quality management into the condensate;
In a combined cycle power generation facility having
A combined cycle power generation characterized in that an inlet for injecting a pH adjusting agent and a deoxygenating agent for water quality management is provided either directly on the low pressure drum or on a pipe connected to the low pressure drum. Facility. In the combined cycle plant equipment according to claim 1,
The combined cycle power generation facility is characterized in that the pipe connected to the low pressure drum is a downcomer of the low pressure drum. In the combined cycle power generation facility according to claim 1,
The combined cycle power generation facility characterized in that the pipe connected to the low-pressure drum is a medium-high pressure water supply pipe connected to the downstream side of the low-pressure drum. In the combined cycle power generation facility according to claim 1,
While providing a deaerator upstream of the low-pressure drum,
The combined cycle power generation facility characterized in that the pipe connected to the low pressure drum is a pipe connecting the deaerator and the low pressure drum. In the combined cycle power generation facility according to claim 1,
While providing a deaerator upstream of the low-pressure drum,
The pipe connected to the low-pressure drum is a pipe connecting the deaerator and the low-pressure drum and a condensate water supply pipe connected to the deaerator. In the combined cycle power generation facility according to claim 5,
The combined cycle power generation facility, wherein the condensate water supply pipe includes a low-pressure economizer. When adding a pH adjuster and oxygen scavenger to the condensate where the exhaust steam from the low-pressure steam turbine is condensed,
In addition to injecting through a chemical injection system provided in a condensate water supply pipe for supplying the condensate from a low pressure turbine to a low pressure drum,
Water quality management of a combined cycle power generation facility, wherein the pH adjusting agent and the oxygen scavenger are injected directly into the low pressure drum or from an inlet provided in any one of pipes connected to the low pressure drum. Method. In the water quality management method of the combined cycle power generation facility according to claim 7,
The pipe connected to the low-pressure drum is a downcomer of the low-pressure drum, and is a water quality management method for a combined cycle power generation facility. In the water quality management method of the combined cycle power generation facility according to claim 7,
The pipe connected to the low-pressure drum is a medium-high pressure water supply pipe connected to the downstream side of the low-pressure drum, and is a water quality management method for a combined cycle power generation facility. In the water quality management method of the combined cycle power generation facility according to claim 7,
While providing a deaerator upstream of the low-pressure drum,
The pipe connected to the low-pressure drum is a pipe connected to the deaerator and the low-pressure drum.

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