JP2005273952A - Desuperheater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a desuperheater having excellent reliability and durability. <P>SOLUTION: This desuperheater comprises a spray nozzle 5 having a plurality of jetting holes 16 jetting a low temperature fluid 1 to a high temperature fluid 2 flowing in a desuperheater main pipe 9. A plurality of pipes 17 communicating with the plurality of jetting holes 16 are inserted into the spray nozzle 5, and flow control valves 20 regulating the flow of the low temperature fluid 2 are installed in the pipes 17. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a temperature reducing device that injects a low-temperature fluid into a high-temperature fluid in order to perform steam temperature control of a business boiler, an industrial boiler, etc., and relates to a temperature reduction device excellent in reliability and durability. It is.

FIG. 5 is a schematic system diagram of a boiler adopting the exhaust gas recirculation combustion method.
In the figure, 51 is a boiler furnace, 52 is a water cooling wall surrounding the boiler furnace 51, 53 is a burner, 54 is a convection heat transfer section of the boiler, 55 and 56 are superheaters and reheaters disposed in the convection transfer section 54. An aging unit, 57 is a boiler flue, 58 is a economizer, 59 is an exhaust gas recirculation fan, 60 is an exhaust gas circulation system for recirculating exhaust gas from the flue 57 at the boiler outlet to the furnace bottom 61 of the boiler furnace 51, 62 Is a damper for controlling the amount of exhaust gas in the exhaust gas recirculation system 60, 63 is a temperature reducing device provided at the inlet of the superheater 55, 64 is a water injection regulating valve, 65 is a cooling water pipe, and 66 is a steam pipe.

  In such a structure, fuel and air are introduced from a fuel system (not shown) and a combustion air system into a burner 53 of a boiler furnace 51 constituted by a water-cooled wall 52 and burned, and mainly from the burner 53 by radiant heat from a high-temperature flame. The working medium (water) flowing in the water-cooled wall 52 is heated and evaporated, and this working medium is further guided to the superheater 55 and the reheater 56 of the convection heat transfer section 54, and a predetermined temperature is generated from the boiler furnace 51 by the high-temperature combustion gas. Heated to steam conditions.

  In this type of power generation boiler, it is necessary to keep the steam temperature at the outlet of the superheater 55 and the reheater 56 constant over the widest possible range in order to maintain power plant efficiency.

  As a feature of recent power demand, thermal power generation has shifted from base load to load adjustment, and is forced to start and stop frequently and load changes. For this reason, the steam flow rate and steam temperature must be adjusted as the load changes, and the steam temperature fluctuates to adjust the feed water flow rate and fuel input, and the spray water is forced by a temperature reducing device to control the steam temperature. Will be injected.

However, in this temperature reducing device, when the number of spray water injections increases, thermal stress is generated in the spray nozzle. In order to reduce the thermal stress, the spray nozzle has a double pipe structure, and the spray nozzle itself has been improved (durability and reliability). (See Patent Document 1 below)
The spray water in the re-maturation system is an intermittent control system that is introduced when the load changes in order to increase boiler efficiency. FIG. 6 shows an example of a system diagram of the reheater system.

  In the figure, the steam discharged from the high-pressure turbine is sent to the primary reheater pipe 72 through the primary reheat steam pipe 71, where it is superheated and sent to the secondary reheater 73. Moreover, when steam is sent from the primary re-maturator 72 to the secondary re-heater 73, low-temperature spray water is injected from the spray nozzle in the reheater temperature reducing device 74 so as to keep the steam temperature constant.

  In addition, spray water is injected into the entrainment tube by providing a spray hole at a spray nozzle portion which is substantially in the center of the reheater temperature reducing device 74, from which a low temperature fluid (spray water) is sprayed into a high temperature fluid. The

  In the figure, reference numeral 75 denotes a primary ripening device lower header, 76 denotes a primary ripening device upper header, 77 denotes a secondary ripening device lower header, and 78 denotes a secondary ripening device upper header.

  By the way, at the time of spray water injection, this low-temperature fluid (spray water) flows into the reheater temperature reducing device 74 in which high-temperature steam is flowing, and a thermal stress is repeatedly generated due to a large temperature difference in the spray nozzle or the like, resulting in a decrease in life. Furthermore, it was a cause of damage.

  In order to prevent this phenomenon, the conventional temperature reducing apparatus has a structure as shown in FIG. In the figure, 81 is spray water, 82 is reheater inlet steam, 83 is spray nozzle cooling steam (buffer medium), 84 is an inlet nozzle, 85 is a spray nozzle, 86 is a spray nozzle protection cylinder, 87 is an opening, and 88 is spray nozzle cooling. Steam pipe, 89 is a temperature reducing device mother pipe, 90 is a protective cylinder, 91 is a diaphragm, 92 is a spray nozzle body, 93 is a cylinder, 94 is an end plate, 95 and 96 are nozzle insertion holes, 97 is a nozzle, 99 Is the tip of the spray nozzle protection cylinder 86.

As shown in the figure, a double-pipe structure in which a spray nozzle protective cylinder 86 is provided around the spray nozzle 85 so that the reheater inlet steam (hot fluid) 82 does not directly contact the spray nozzle 85. A spray nozzle cooling steam (buffer medium having an intermediate temperature between the reheater steam temperature and the spray water temperature) 83 is allowed to flow between the spray nozzle 85 and the protective cylinder 86 to reduce thermal stress by intermittent injection of spray water. I am trying.
JP-A-1-193508

  By the way, in the conventional temperature reducing device, when the spray pressure of the spray water for cooling is sufficient, the spray water 81 does not roll back to the surface of the protective cylinder 86. However, when the spray pressure decreases, the spray water 81 sprayed from the spray nozzle 85 is It rolls back and enters the inside of the protective cylinder 86 or adheres to the outer surface. And this becomes a trigger and there exists a problem that damage, such as a crack, arises in a part of protection cylinder 86 by the thermal fatigue by repetition of high and low temperature.

  The portion where the damage occurs is slightly different depending on the opening edge of the opening 87 formed on the peripheral surface of the protective cylinder 86, the reheat steam, the spray water sprayed, the flow velocity of the intermediate temperature steam flow, etc. From 5 to 10 cm, the countermeasure for reducing the influence of the rewinding of the spray water 81 has been demanded.

  An object of the present invention is to provide a temperature reducing device that eliminates the drawbacks of the prior art and is excellent in reliability and durability.

  In order to achieve the above object, the first means of the present invention is the temperature reducing device comprising a spray nozzle having a plurality of injection holes for injecting a low temperature fluid into the high temperature fluid circulating in the temperature reducing device mother pipe. A plurality of pipes communicating with the plurality of injection holes are inserted inside the pipe, and a flow rate adjusting valve for adjusting the flow rate of the low-temperature fluid is attached to each pipe.

  According to a second means of the present invention, in the first means, a bent portion is formed in each pipe in the spray nozzle.

  According to a third means of the present invention, in the first means, a spray nozzle protection cylinder is disposed outside the spray nozzle at a predetermined interval to form a double pipe structure. A buffer fluid having an intermediate temperature between the spray nozzle and the spray nozzle protective cylinder is allowed to flow.

  The present invention has the above-described configuration, can prevent thermal fatigue cracking due to rewinding of spray water sprayed from the spray nozzle, and can provide a temperature reducing device excellent in durability and reliability.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of the temperature reducing device according to the first embodiment. In the figure, 1 is spray water, 2 is reheater inlet steam, 3 is spray nozzle cooling steam (buffer fluid), 4 is an inlet nozzle, 5 is a spray nozzle, 6 is a spray nozzle protective cylinder, 7 is an opening, and 8 is spray nozzle cooling. Steam pipe, 9 is a temperature reducing device mother pipe, 10 is a protective cylinder, 11 is a diaphragm, 12 is a spray nozzle body, 13 is a cylinder body, 14 is an end plate, 15 is a nozzle, 16 is an ejection hole, 17 is a pipe, 18 Is a distribution member.

  As shown in the figure, the spray nozzle body 12 is installed from the inlet nozzle 4 to the lower part of the temperature reducing device mother pipe 9 so as to penetrate the temperature reducing device mother pipe 9. The spray nozzle 5 has a double pipe structure in which a spray nozzle protective cylinder 6 is provided at a predetermined interval around the spray nozzle 5 so that the reheater inlet steam (high temperature steam) 2 does not directly touch the spray nozzle 5.

  An oval opening 7 is provided in a portion of the peripheral surface of the spray nozzle protective cylinder 6 that is substantially in the center of the temperature reducing device mother pipe 9, and an axial direction is provided at a position facing the opening 7 on the peripheral surface of the spray nozzle 5. Eight ejection holes 16a to 16h are formed along the line.

The directions of the eight ejection holes 16a to 16h are alternately downward and upward.

  Three pipes 17a to 17c are inserted inside the spray nozzle 5, a first distribution member 18a and a second distribution member 18b are provided at the tip of the first pipe 17a, and a third distribution member is provided at the tip of the second pipe 17b. The fourth distribution member 18d is connected to the tip of the third pipe 17c.

  As shown in FIG. 2, the four jet holes 16c to 16f located at the center of the eight jet holes 16a to 16h are connected to the first pipe. The first distribution member 18a and the second distribution member 18b connected to 17a, the third distribution member 18c connected to the second pipe 17b to the ejection hole 16g and the ejection hole 16h, and the third pipe 17c. The 4th distribution member 18d connected is connected, respectively. Appropriate means such as welding, brazing, and caulking are selected for attachment of each distribution member 18 to the spray nozzle 5.

  As shown in FIG. 1, the base ends of the pipes 17 a to 17 c arranged in the spray nozzle 5 are fixed to the injection tube base 21, and the tip ends are fixed to the spray nozzle 5 via the distribution member 18. A difference in thermal expansion occurs based on the temperature difference between the spray nozzle 5 and each of the pipes 17a to 17c generated in the process of starting up to operating and stopping the boiler device. In order to absorb this difference in thermal expansion, a bent portion 22 is formed in the middle of each of the pipes 17a to 17c, thereby forming a flexible structure.

  FIG. 3 is a supply system diagram of the spray water 1. As shown in the figure, a shut-off valve 19 is provided on the spray water 1 supply system, the downstream side is divided into three pipes 17a to 17c, and the flow rate adjusting valves 20a to 20c are individually provided on the pipes 17a to 17c. 20c is attached. The temperature detector 23 detects the outlet steam temperature of the reheater, and the steam temperature detection signal is input to the control unit 24. The opening / closing operations of the shutoff valve 19 and the flow rate adjusting valves 20a to 20c are individually controlled by the control signal from the control unit 24.

  When the shutoff valve 19 is turned on / off, the spray water 1 is intermittently injected into the temperature reducing device main pipe 9, and when the spray water 1 is injected, the amount of water injection is adjusted by the opening degree of the flow rate adjusting valves 20a to 20c. Thus, even if the injection amount of the spray water 1 changes, the spray water injection characteristics (injection pressure) of the ejection holes 16 can be controlled to be always in a good state.

  When the spray water flow rate is large, the flow rate regulating valves 20a to 20c are fully opened or close to this, and the spray water 1 is injected from the eight ejection holes 16a to 16h. At this time, since the flow rate of the spray water is large, the spray water 1 is ejected vigorously from each of the ejection holes 16a to 16h, so that the spray water 1 is not rewound.

  On the other hand, when the reheater outlet steam temperature is lowered and the spray water flow rate is decreased, based on the control signal from the control unit 24, only the flow rate adjustment valve 20a is fully opened or close to it. The spray holes 16 for spraying the spray water 1 with the 20b and 20c fully closed or close thereto are limited to the four spray holes 16c to 16f at the center. Then, even if the spray water flow rate is small, the spray water 1 is ejected vigorously from the ejection holes 16c to 16f. In this case, the spray water 1 is not rewound.

  At this time, the spray water 1 is not supplied to the pipes 17 b and 17 c, but the spray nozzle 5 in which the pipes 17 a to 17 c are accommodated is disposed in the spray nozzle protection cylinder 6, and between the spray nozzle 5 and the spray nozzle protection cylinder 6. Since the buffer fluid 3 circulates, thermal damage to the pipes 17b and 17c can be effectively prevented.

  FIG. 4 is an enlarged cross-sectional view of the vicinity of the ejection hole of the temperature reducing device according to the second embodiment.

The present embodiment is different from the first embodiment in that a pipe 17 and a distribution member 18 are individually connected to a set of two ejection holes 16. Also in this embodiment, when the flow rate of the spray water is small, the spray water 1 is sprayed out with a limited force by ejecting holes 16 for spraying the spray water 1.

  In the above-described embodiment, the case where the spray nozzle 5 and the spray nozzle protection cylinder 6 have a double pipe structure has been described. However, the present invention is not limited to this and can be applied to a temperature reducing device that does not use the spray nozzle protection cylinder 6. It is.

It is sectional drawing of the temperature decreasing apparatus which concerns on the 1st Embodiment of this invention. It is an expanded sectional view near the ejection hole in the temperature reducing device. It is a supply system diagram of spray water. It is an expanded sectional view of the jet hole vicinity of the temperature decreasing apparatus which concerns on the 2nd Embodiment of this invention. 1 is a schematic system diagram of a boiler that employs an exhaust gas recirculation combustion method. It is one system diagram of the reheater system of the boiler. It is sectional drawing of the conventional temperature reducing apparatus.

Explanation of symbols

  1: spray water, 2: reheater inlet steam, 3: spray nozzle cooling steam, 4: inlet nozzle, 5: spray nozzle, 6: spray nozzle protective cylinder, 7: spray tube insertion hole, 8: spray nozzle cooling steam pipe, 9: Temperature reducing device mother pipe, 10: protective cylinder, 11: diaphragm, 12: spray nozzle body, 13: cylinder, 14: end plate, 15: nozzle, 16a to 16h: ejection hole, 17a to 17c: pipe, 18a to 18d: Distributing member, 19: Shut-off valve, 20a to 20c: Flow rate adjusting valve, 21: Injection nozzle, 22: Bending part, 23: Temperature detector, 22: Control part.

Claims (3)

In the temperature reducing device provided with the spray nozzle having a plurality of ejection holes for ejecting the low temperature fluid to the high temperature fluid circulating in the temperature reducing device mother pipe,
A temperature reducing device, wherein a plurality of pipes communicating with the plurality of injection holes are inserted inside the spray nozzle, and a flow rate adjusting valve for adjusting a flow rate of the low-temperature fluid is attached to each pipe.   2. The temperature reducing apparatus according to claim 1, wherein a bent portion is formed in each pipe in the spray nozzle.   2. The temperature reducing device according to claim 1, wherein a spray nozzle protective cylinder is disposed outside the spray nozzle at a predetermined interval to form a double pipe structure, and is intermediate between the temperature of the hot fluid and the temperature of the cold fluid. A temperature reducing device characterized in that a buffer fluid having temperature flows between the spray nozzle and the spray nozzle protective cylinder.

Images