WO2016129432A1 - Boiler feed-water system, boiler provided with said system, and control method for boiler feed-water system - Google Patents

Boiler feed-water system, boiler provided with said system, and control method for boiler feed-water system Download PDF

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Publication number
WO2016129432A1
WO2016129432A1 PCT/JP2016/052861 JP2016052861W WO2016129432A1 WO 2016129432 A1 WO2016129432 A1 WO 2016129432A1 JP 2016052861 W JP2016052861 W JP 2016052861W WO 2016129432 A1 WO2016129432 A1 WO 2016129432A1
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Prior art keywords
water
path
boiler
temperature
feed
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PCT/JP2016/052861
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French (fr)
Japanese (ja)
Inventor
正広 天野
浩市 松下
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三菱重工業株式会社
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Application filed by 三菱重工業株式会社 filed Critical 三菱重工業株式会社
Priority to KR1020177021158A priority Critical patent/KR101844205B1/en
Priority to CN201680009315.XA priority patent/CN107208876B/en
Publication of WO2016129432A1 publication Critical patent/WO2016129432A1/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B1/00—Methods of steam generation characterised by form of heating method
    • F22B1/02—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers
    • F22B1/18—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers the heat carrier being a hot gas, e.g. waste gas such as exhaust gas of internal-combustion engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
    • F22D1/00—Feed-water heaters, i.e. economisers or like preheaters
    • F22D1/003—Feed-water heater systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
    • F22D1/00—Feed-water heaters, i.e. economisers or like preheaters
    • F22D1/02—Feed-water heaters, i.e. economisers or like preheaters with water tubes arranged in the boiler furnace, fire tubes, or flue ways
    • F22D1/12—Control devices, e.g. for regulating steam temperature

Definitions

  • the present invention relates to a boiler water supply system, a boiler including the same, and a control method of the boiler water supply system.
  • the feed water temperature supplied to the feed water heating economizer is higher than the temperature that prevents low temperature corrosion (for example, 135 ° C or higher) It is necessary to raise the water supply temperature so that
  • a deaerator (deaerator) is installed to remove dissolved oxygen in the water supply.
  • the feed water is heated when the deaerator is charged with steam for removing dissolved oxygen, it has been possible to raise the feed water temperature to such an extent that low temperature corrosion of the feed water heating economizer can be prevented. .
  • Patent Document 3 part of the water supplied to the economizer is returned from the outlet side of the economizer to the inlet side of the economizer, and the water supplied from the water supply pump and the returned water merge.
  • a technique for raising the temperature of the water flowing into the economizer is described.
  • JP 2012-177519 A Japanese Patent Laid-Open No. 7-217802 Patent No. 5117197 gazette
  • Patent Document 1 can prevent low temperature corrosion of the economizer for feed water heating by heating the feed water using a deaerator, but if a heater such as a dealator is purposely installed to heat the feed water, cost will be reduced. In addition, there is a problem that an additional arrangement space for the heater is required. Particularly in the case of a marine auxiliary boiler installed in a ship, it is not practical to install a heater for feedwater heating because the installation space in the ship is limited.
  • the present invention has been made in view of such circumstances, and it is a boiler water supply system that prevents low temperature corrosion and reduces the space and space costs, a boiler including the same, and a control method of the boiler water supply system. Intended to be provided.
  • Another object of the present invention is to provide a boiler water supply system, a boiler including the same, and a control method of the boiler water supply system, in which the lowering of the water level of the drum can be suppressed.
  • a first path which is a path for supplying water supplied to a feed water heating economizer that exchanges heat with boiler water in a steam drum of a boiler with heat exhaust gas from a furnace; And a second route which branches from the first route before heat exchange and bypasses the steam drum and merges with the first route at a junction on the inlet side of the feed water heating economizer, and the second route
  • a water supply system including a third path branched and supplying water to the steam drum, temperature detection means for detecting a water temperature between the junction and the economizer for water supply heating, the first path and the second path Flow rate adjusting means for adjusting the flow rate of water flowing through the third path and the water temperature detected by the temperature detecting means so that the water temperature detected by the temperature detecting means is equal to or higher than a predetermined temperature for preventing low temperature corrosion of the feedwater heating economizer
  • Flow And control means for adjusting the adjustment means is a boiler water supply system having
  • the water flowing through the first path is heated by heat exchange with the boiler water in the steam drum.
  • the feed water temperature flowing into the feed water heating economizer becomes equal to or higher than the predetermined temperature which prevents low temperature corrosion Can be adjusted and maintained.
  • a large-scale separate feed water heating device for example, a deaerator
  • the feedwater temperature flowing into the feedwater heating economizer can be adjusted. That is, if the flow rate of water in the second and third paths is adjusted and water is circulated in the second path and water is not circulated in the third path, the water in the first path heated by the boiler water is The two paths merge with the unheated water bypassing the steam drum and the temperature is lowered.
  • the heat recovery efficiency of the feed water heating economizer can be achieved by securing a large temperature difference with the combustion exhaust gas as the heating medium. Can be improved.
  • the first path of the boiler water supply system supplies water to a heat transfer pipe provided in boiler water in the steam drum, and water in the heat transfer pipe and the boiler water in the steam drum The heat may be exchanged.
  • the heat transfer pipe provided in the boiler water serves as a heater for heating the feed water and heats the feed water using the heat transfer pipe, the water level does not fall compared to the technique for extracting the boiler water in the steam drum. As a result, stable steam pressure can be output from the steam drum, and it is possible to avoid airing due to excessive water level drop.
  • the boiler of the boiler water supply system according to the first aspect of the present invention may be an auxiliary boiler.
  • low temperature corrosion can be prevented with respect to the feed water heating economizer provided in the auxiliary boiler.
  • an auxiliary boiler having a lower steam pressure than the main boiler is particularly useful because it is less necessary to install a deaerator.
  • the second path is closed when the temperature detected by the temperature detection means is lower than the predetermined temperature, and the first path and the third path The flow rate of water flowing to the
  • the temperature of the water flowing through the first path can be lowered by closing the second path.
  • the amount of water circulated in the first route it is possible to control the water temperature to increase.
  • the third path is closed when the temperature detected by the temperature detection means exceeds the predetermined temperature by a predetermined value or more.
  • the flow rate of water flowing to the second path may be adjusted.
  • the temperature of the water flowing through the first route is set by opening the second route. It can be lowered and controlled to lower the water temperature.
  • the flow rate in the flow rate adjusting means is set by setting the threshold value when performing control to lower the water temperature supplied to the feed water heating economizer as a temperature larger than the predetermined temperature by the predetermined value or more from the predetermined temperature. Control can be prevented from being switched frequently.
  • a second aspect of the present invention is a boiler including the boiler water supply system according to any one of the above.
  • a first path which is a path for supplying water supplied to a feed water heating economizer which exchanges heat with boiler water in a steam drum of a boiler with exhaust gas from a furnace, and the boiler water
  • a second route which branches from the first route before heat exchange and bypasses the steam drum and merges with the first route at a junction on the inlet side of the feed water heating economizer, and the second route
  • a control method for a boiler water supply system comprising a water supply system including a third path branched and supplying water to the steam drum, wherein a water temperature between the junction and the water supply heating economizer is detected, and the water temperature is detected.
  • the present invention can prevent low temperature corrosion of the feed water heating device, and can achieve cost reduction with space saving. Further, the present invention has an effect that the water level drop of the drum can be suppressed.
  • FIG. 1 shows a schematic configuration of a marine exhaust heat recovery system 1 provided with a boiler water supply system according to the present embodiment.
  • the marine exhaust heat recovery system 1 of the present embodiment includes a main engine 3, an exhaust heat recovery mechanism 4, an auxiliary boiler 10, and a feedwater heating economizer 2.
  • the main engine 3 is a ship propulsion engine, and for example, a diesel engine or a main boiler is used.
  • the main engine 3 rotates a propeller (not shown) provided on the drive shaft by driving a drive shaft (not shown). Exhaust gas from the main engine 3 is led to an exhaust heat recovery mechanism 4 via an exhaust pipe 6.
  • an exhaust gas economizer is used as the exhaust heat recovery mechanism 4.
  • the exhaust heat recovery mechanism 4 generates steam using the exhaust gas of the main engine 3 and supplies the generated steam as a miscellaneous steam to a steam turbine (not shown) or the like.
  • the exhaust gas subjected to heat exchange in the exhaust heat recovery mechanism 4 is discharged from the chimney 5 to the outside of the system.
  • the auxiliary boiler 10 includes a steam drum 11, and generates steam by burning a fuel.
  • the auxiliary boiler 10 is a boiler that is mounted on a ship and responds to the heat demand in the ship.
  • the auxiliary boiler 10 is a natural circulation type or a forced circulation type boiler.
  • the steam drum 11 is a drum (boiling water drum) that stores the steam obtained by the auxiliary boiler 10.
  • the space above the steam drum 11 is occupied by steam, and the boiler water is stored below the space.
  • the steam pressure of the auxiliary boiler 10 is 0.2 MPa or more and 6 MPa or less, and typically 2 MPa or less.
  • the water temperature in the steam drum 11 in the present embodiment is about 210 ° C. when the steam pressure of the auxiliary boiler 10 is 2 MPa.
  • the auxiliary boiler 10 is used as a power source and heating medium for a steam drive device 7 (for example, a cargo oil pump turbine (COPT: Cargo Oil Pump Turbine) that drives a crude oil unloading pump (cargo oil pump) etc.) in a ship. It is also used for hot water heating for kitchens and generation of inert gas.
  • COT Cargo Oil Pump Turbine
  • a water supply system 21 which is a water supply path is connected to the water supply heating economizer 2.
  • the feed water heating economizer 2 heats the water supplied to the steam drum 11 by exchanging heat with the exhaust gas discharged from the auxiliary boiler (boiler) 10, and supplies the heated water to the steam drum 11.
  • the boiler water supply system 20 includes a water supply system 21, a heater 23 provided in the steam drum 11, a temperature detection unit (temperature detection means) 24, and a flow rate adjustment unit (flow rate adjustment means). ), A control unit (control means) 26, and a boiler water supply path 27. 2 differs from FIG. 1 in that the feed water heating economizer 2 is positioned below the steam drum 11. However, in order to clearly show the feed water system 21, this ignores the vertical relationship of the actual arrangement. For the sake of convenience. Therefore, in general, the feed water heating economizer 2 is located above the steam drum 11.
  • the water supply system 21 includes a first path 21a, a second path 21b, and a third path 21c.
  • the first path 21a is a path for supplying water, which has been heat-exchanged with the boiler water in the steam drum 11 of the auxiliary boiler 10, to the feedwater heating economizer 2 which exchanges heat with the exhaust gas from the furnace.
  • the first path 21a includes a path 21a1 for supplying water to the steam drum 11, a heat transfer pipe 21a2 constituting the heater 23, and a path 21a3 for supplying water from the steam drum 11 to the feed water heating economizer 2 .
  • the first path 21 a is a path for supplying water to the heat transfer pipe 21 a 2 provided in the boiler water 12 in the steam drum 11 of the auxiliary boiler 10 and supplying the water heat-exchanged with the boiler water to the feed water heating economizer 2.
  • the water supply temperature of the path 21a1 supplied from the water supply source is, for example, 60 ° C. to 80 ° C., and water having a temperature lower than the water temperature in the steam drum 11 is supplied.
  • the second path 21 b includes a path 21 b 1, a path 21 b 2, and a flow rate adjustment unit 25.
  • the second path 21b branches from the path 21a1 of the first path 21a on the inlet side for supplying water to the heat transfer pipe 21a2 in the boiler water, bypasses the steam drum 11, and merges at the junction X on the inlet side of the feedwater heating economizer 2 It is a route until it merges with the route 21a3 of the first route 21a.
  • the flow rate adjusting unit 25 is provided between the junction point X and the branch point Z branched from the path 21a1 of the first path 21a.
  • the path 21 b 1 is a path from the branch point Z to the flow rate adjustment unit 25, and the path 21 b 2 is a path from the flow rate adjustment unit 25 to the junction point X.
  • the third path 21c branches from the second path 21b via the flow rate adjustment unit 25 connecting the path 21b1 and the path 21b2, joins at the junction point Y with the boiler water supply path 27, and supplies water to the steam drum 11. .
  • the boiler feed water path 27 supplies the water heat-exchanged by the feed water heating economizer 2 to the steam drum 11.
  • the third path 21c merges with the boiler water supply path 27 and supplies water to the steam drum.
  • the third path 21c and the boiler water supply path 27 are separate paths.
  • the steam drum 11 may be supplied with water.
  • the heater 23 passes the heat transfer pipe 21a2 through the boiler water 12 of the steam drum 11, and heats the water flowing through the heat transfer pipe 21a2. Thereby, the feed water is heated using the sensible heat which the boiler water in the steam drum 11 holds. In this manner, in the heat transfer pipe 21a2 of the boiler water 12 in the steam drum 11, heat is exchanged between the boiler water in the steam drum 11 (outside of the heat transfer pipe 21a2) and the water in the heat transfer pipe 21a2 to heat it indirectly Heat exchange is adopted. For this reason, unlike the technique of extracting boiler water from a steam drum and using it for adjustment of the water temperature of feed water, fluctuation of the water level of the boiler water can be prevented as much as possible.
  • the temperature detection unit 24 detects the water temperature between the junction point X and the feed water heating economizer 2, and outputs information on the detected water temperature to the control unit 26.
  • the temperature detection unit 24 is, for example, a temperature sensor such as a thermocouple.
  • the flow rate adjustment unit 25 adjusts the flow rate of water flowing through the first path 21a, the second path 21b, and the third path 21c.
  • the flow rate adjustment unit 25 is, for example, a three-way valve (control valve), and is provided at a branch point between the path 21b1 and the path 21b2 and the third path 21c in the second path 21b branched from the first path 21a. Further, the flow rate adjusting unit 25 is not limited to the three-way valve, but two-way valves (control valves) are provided in each of the second path 21b and the third path 21c, and flow is made in each path by controlling each two-way valve. The flow rate of water may be adjusted.
  • the control unit 26 adjusts the flow rate adjusting unit 25 so that the water temperature detected by the temperature detection unit 24 is equal to or higher than a predetermined temperature (for example, 135 ° C.) that prevents low temperature corrosion of the feedwater heating economizer 2.
  • a predetermined temperature for example, 135 ° C.
  • 135 ° C is used, for example.
  • the ratio of the amount of water to be circulated is appropriately adjusted arbitrarily in order to obtain a desired temperature in the temperature detection unit 24. For example, information on the change in the water temperature Tout at the outlet of the steam drum 11 when water is supplied to each path at a predetermined rate by a preliminary test or the like is obtained based on a table or the like.
  • FIG. 3 shows changes in the respective parameters when the command given to the steam driving device 7 which is a plant operated by the steam supplied from the steam drum 11 changes.
  • the amount of generated steam in the steam drum 11 corresponding to the change in load changes.
  • the steam pressure in the steam drum 11 changes.
  • a factor that changes the water temperature Tout is a change in the amount of steam generation.
  • the feed water flow rate corresponding to the change in the steam generation amount changes, and as a result, the water temperature Tout changes.
  • the load on the steam driving device 7 increases, the amount of generated steam corresponding to the increase in load increases, and the feed water flow rate increases to meet the increase in the amount of steam generation.
  • the feed water flow rate increases, the amount of water that needs to be heated by the heat transfer pipe 21a2 corresponding to the heat exchanger increases, so the water temperature Tout decreases.
  • the load of the steam drive device 7 decreases, the opposite action occurs.
  • the steam pressure in the steam drum 11 changes, and the amount of fuel input to the auxiliary boiler 10 changes so as to return to the rated pressure.
  • the load of the steam driving device 7 increases and the required amount of generated steam increases, a large amount of steam will be carried out from the inside of the steam drum 11 to the external steam driving device 7.
  • the pressure in the drum 11 is temporarily reduced.
  • the pressure in the steam drum 11 which has temporarily decreased is increased to return to the rated pressure, so the amount of fuel input to the auxiliary boiler 10 is increased.
  • the load of the steam drive device 7 decreases, the opposite action occurs.
  • the water supply system is performed so that the water temperature measured by the temperature detection unit 24 is equal to or higher than a predetermined temperature (for example, 135 ° C.) that prevents low temperature corrosion of the economizer 2 for water supply heating. Adjust the flow rate of water flowing through 21.
  • a predetermined temperature for example, 135 ° C.
  • the path 21b2 of the second path 21b is closed, and the path 21b1 of the second path 21b and the third path 21c are open.
  • the flow rate of water flowing to the third path 21c is adjusted.
  • the temperature of the water flowing through the first path 21a is not lowered by the water led from the path 21b2 of the second path 21b, so that the water temperature can be controlled to be increased.
  • the second path 21 b is opened and the third path 21 c is closed.
  • the flow rate of water flowing through the path 21b (path 21b1 and path 21b2) and the third path 21c is adjusted.
  • the temperature of the water flowing through the first path 21a can be controlled to be lowered.
  • FIGS. 4 and 5 show flow control in accordance with the difference between the temperature detected by the temperature detection unit 24 and 135 ° C. which is the target temperature (predetermined temperature).
  • the vertical axis in FIG. 4A indicates the temperature
  • the vertical axis in FIG. 4B indicates the ratio of the flow rate of the first path 21a to the flow rate of the path 21b2 of the second path 21b. As shown in FIG.
  • the temperature detection unit In order to bring the temperature detected by the sensor 24 close to the predetermined temperature, the ratio of the flow rate of the path 21b2 of the second path 21b to the flow rate of the first path 21a is increased as shown in FIG.
  • the feedwater temperature flowing into the feedwater heating economizer 2 is adjusted by appropriately adjusting the flow rate ratio between the first path 21a and the path 21b2 of the second path 21b according to the temperature difference between the detected temperature and the target temperature. It can be lowered.
  • the ratio of the flow rate of the path 21b1 and the third path 21c to the flow rate of the first path 21a is increased as shown in FIG.
  • the feedwater temperature flowing into the feedwater heating economizer 2 can be increased by appropriately adjusting the flow rate ratio of the first path 21a and the third path 21c according to the temperature difference between the detected temperature and the target temperature.
  • the auxiliary boiler 10 including the same, and the control method of the boiler water supply system 20, the water flowing through the first path 21 a is the steam drum 11. Heat is exchanged with the water in the steam drum 11 and heated in a heat transfer pipe 21a2 provided in the boiler water 12 inside. That is, the heat transfer pipe 21a2 provided in the boiler water 12 serves as the heater 23 for heating the feed water.
  • the feed water flowing into the feed water heating economizer 2 is maintained at a predetermined temperature or more to prevent low temperature corrosion by heating the feed water using the stored heat of the boiler water in the steam drum 11 of the conventionally equipped boiler can do.
  • the feed water is heated using the heat transfer pipe 21a2
  • the water level does not decrease compared to the technique of extracting the boiler water in the steam drum 11.
  • the boiler can be operated at a stable steam pressure, and the open air due to excessive water level drop can be avoided.
  • the flow rate of water in the second path 21b and the third path 21c is adjusted, and water is not circulated in the second path 21b and the path 21b1 and the second path 21b2.
  • the water of the first path 21a heated by the heat pipe 21a2 is joined with the unheated water bypassed the steam drum 11 by the second path 21b, and the temperature is lowered.
  • the heat in the feed water heating economizer 2 can be reduced by securing a large temperature difference with the combustion exhaust gas as the heating medium. Recovery efficiency can be improved.
  • the flow rate of water in the second route 21b and the third route 21c is adjusted, water will not flow in the second route 21b, and water will flow in the second route 21b1 and the third route 21c. Since the flow rate of the first path 21a is relatively decreased by the increase of the amount of water supplied to the steam drum 11 from the third path 21c, the water heated by the heat transfer pipe 21a2 becomes high temperature and the temperature is raised. In addition, the temperature of the water flowing through the first path 21a is not lowered by the water led from the path 21b2 of the second path 21b.
  • the temperature of the feed water flowing into the feed water heating economizer 2 can be adjusted to a desired temperature above the predetermined temperature which prevents low temperature corrosion.
  • a large-scale water supply heating device such as a deaerator (deaerator) is not required, and an extra arrangement space is not used.
  • indirect heat exchange is performed in which heat is exchanged between the water in the steam drum 11 (at the outside of the heat transfer tube 21a2) and the water in the heat transfer tube 21a2 in the heat transfer tube 21a2 of the boiler water 12 in the steam drum Is adopted. That is, unlike the technique of extracting boiler water from a steam drum and using it for adjustment of the water temperature of water supply, this embodiment can prevent fluctuation of the water level of boiler water as much as possible.
  • the feed water temperature on the inlet side of the feed water heating economizer 2 can be controlled, and the feed water temperature can be lowered to a predetermined temperature (for example, 135 ° C.) for preventing low temperature corrosion.
  • a predetermined temperature for example, 135 ° C.
  • the flow rate adjusting unit 25 is controlled with the predetermined temperature set to, for example, 135 ° C. as a target value, but a predetermined temperature range may be given to the target temperature.
  • the predetermined temperature may have an allowable range of 5 ° C. as a range from 135 ° C. to 140 ° C. of plus 5 ° C., and the flow rate control in the flow rate adjusting unit 25 can be prevented from being switched frequently.

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Abstract

The present invention addresses the problem of preventing low-temperature corrosion of a feed-water heating device, installing a feed-water heating device so as to save space and suppress cost, and suppressing a drop in the water level in a drum. A boiler feed-water system is provided with a feed-water system (21) that has: a first route (21a) that feeds water to a feed-water heating economizer (2) that allows water, whose heat is exchanged with boiler water located inside a steam drum (11), to exchange heat with exhaust gas from a furnace; a second route (21b) that branches off from the first route (21a) before heat exchange with the boiler water occurs, bypasses the steam drum (11), and joins with the first route (21a) at a confluence point (X); and a third route (21c) that branches off from the second route (21b) and feeds water to the steam drum (11). The boiler feed-water system is further provided with: a temperature detection unit (24) that detects the temperature of water between the confluence point (X) and the feed-water heating economizer (2); a flow-rate regulation unit (25) that regulates the flow-rate of water flowing in the feed-water system (21); and a control unit that regulates the flow-rate such the water temperature detected by the temperature detection unit (24) is kept at or above a prescribed temperature that prevents low-temperature corrosion of the feed-water heating economizer (2).

Description

ボイラ給水システム及びそれを備えたボイラ、並びにボイラ給水システムの制御方法Boiler feed system, boiler provided with the same, and control method of boiler feed system
　本発明は、ボイラ給水システム及びそれを備えたボイラ、並びにボイラ給水システムの制御方法に関するものである。 The present invention relates to a boiler water supply system, a boiler including the same, and a control method of the boiler water supply system.
　給水加熱用エコノマイザをボイラの排ガス系統に設置した場合、給水加熱用エコノマイザは低温腐食が生じるおそれがあるので、給水加熱用エコノマイザに供給される給水温度が低温腐食を防ぐ温度以上（例えば１３５℃以上）となるように給水温度を上げる必要がある。例えば下記特許文献１に示すように、ＬＮＧ（Ｌｉｑｕｅｆｉｅｄ　Ｎａｔｕｒａｌ　Ｇａｓ；液化天然ガス）船の主機に用いる主ボイラには、給水中の溶存酸素を除去するためにデアレータ（脱気器）が設置してあるが、デアレータには溶存酸素除去用の蒸気が投入されることにより給水が加熱されるので、給水加熱用エコノマイザの低温腐食を防ぐことができる程度に給水温度を上げることが可能となっていた。 When the feed water heating economizer is installed in the exhaust gas system of the boiler, low temperature corrosion may occur in the feed water heating economizer. Therefore, the feed water temperature supplied to the feed water heating economizer is higher than the temperature that prevents low temperature corrosion (for example, 135 ° C or higher) It is necessary to raise the water supply temperature so that For example, as shown in Patent Document 1 below, in the main boiler used for the main engine of a LNG (Liquefied Natural Gas) vessel, a deaerator (deaerator) is installed to remove dissolved oxygen in the water supply. However, since the feed water is heated when the deaerator is charged with steam for removing dissolved oxygen, it has been possible to raise the feed water temperature to such an extent that low temperature corrosion of the feed water heating economizer can be prevented. .
　また、ボイラ給水を加熱する方法としては、主ボイラのようなドラムボイラとは形式が相違する排熱回収ボイラ（ＨＲＳＧ；ｈｅａｔ　ｒｅｃｏｖｅｒｙ　ｓｔｅａｍ　ｇｅｎｅｒａｔｏｒ）に関するものであるが、以下のものが提案されている。
　下記特許文献２では、蒸気ドラム内の湯の一部を節炭器の給水管に戻して供給し、節炭器の給水管で、給水ポンプから送られてきた水と蒸気ドラム内の湯が混合され、湯の混合で温度上昇した水を節炭器に供給する技術が記載されている。
　下記特許文献３では、節炭器に供給された給水の一部が節炭器の出口側から節炭器の入口側に戻されて、給水ポンプから送られる給水と戻された水が合流して節炭器に流入される水を温度上昇させる技術が記載されている。 In addition, as a method of heating boiler feed water, although it relates to a heat recovery steam generator (HRSG; heat recovery steam generator) whose type is different from that of a drum boiler such as a main boiler, the following are proposed. .
In Patent Document 2 below, part of the hot water in the steam drum is returned to the water supply pipe of the economizer and supplied, and the water supplied from the water supply pump and the hot water in the steam drum are supplied by the water supply pipe of the economizer. A technique is described which supplies mixed water and heated water by mixing it to the economizer.
In Patent Document 3 below, part of the water supplied to the economizer is returned from the outlet side of the economizer to the inlet side of the economizer, and the water supplied from the water supply pump and the returned water merge. A technique for raising the temperature of the water flowing into the economizer is described.
特開２０１２－１７７５１９号公報JP 2012-177519 A 特開平７－２１７８０２号公報Japanese Patent Laid-Open No. 7-217802 特許第５１１７１９７号公報Patent No. 5117197 gazette
　しかしながら、特許文献１は、デアレータを用いて給水が加熱されることにより給水加熱用エコノマイザの低温腐食を防ぐことはできるが、給水を加熱するためにわざわざデアレータ等の加熱器を設置すると、コストがかかり、加熱器用の配置スペースも別途必要となるという問題があった。特に船内に設置される舶用補助ボイラの場合には、船内の設置スペースが限られているため、給水加熱のために加熱器を設置することは現実的でない。 However, Patent Document 1 can prevent low temperature corrosion of the economizer for feed water heating by heating the feed water using a deaerator, but if a heater such as a dealator is purposely installed to heat the feed water, cost will be reduced. In addition, there is a problem that an additional arrangement space for the heater is required. Particularly in the case of a marine auxiliary boiler installed in a ship, it is not practical to install a heater for feedwater heating because the installation space in the ship is limited.
　また、上記特許文献２のように、蒸気ドラムの水を抜き出して排ガスエコノマイザ入口側の給水管に供給すると、蒸気ドラムの水位が変化してドラム中の蒸気圧力が変動するため好ましくない。特に、蒸気ドラムの水位が過剰に下がると空焚きとなる危険性が生じる。また、上記特許文献３のように、節炭器の出口と蒸気ドラムの間の経路から分岐させて節炭器に供給された給水の一部を給水再循環系に戻す場合では、給水再循環系に戻す流量調整弁１２を開き過ぎると蒸気ドラムに十分な給水が行えなくなり、蒸気ドラムの水位が過剰に下がる危険性がある問題は解決できない。 Further, when the water of the steam drum is extracted and supplied to the feed pipe at the inlet of the exhaust gas economizer as in Patent Document 2 described above, the water level of the steam drum changes and the steam pressure in the drum fluctuates, which is not preferable. In particular, if the water level of the steam drum drops excessively, there is a risk of air-bathing. In addition, as in the case of Patent Document 3 described above, in the case where a part of the water supplied to the economizer is branched from the path between the outlet of the economizer and the steam drum and returned to the water supply recirculation system, the water supply recirculation. If the flow rate adjusting valve 12 returned to the system is opened too much, sufficient supply of water to the steam drum can not be performed, and the problem that the water level of the steam drum may be excessively lowered can not be solved.
　本発明は、このような事情に鑑みてなされたものであって、低温腐食を防止し、かつ、省スペースでコストを抑えるボイラ給水システム及びそれを備えたボイラ、並びにボイラ給水システムの制御方法を提供することを目的とする。また、本発明は、ドラムの水位低下が抑えられるボイラ給水システム及びそれを備えたボイラ、並びにボイラ給水システムの制御方法を提供することを目的とする。 The present invention has been made in view of such circumstances, and it is a boiler water supply system that prevents low temperature corrosion and reduces the space and space costs, a boiler including the same, and a control method of the boiler water supply system. Intended to be provided. Another object of the present invention is to provide a boiler water supply system, a boiler including the same, and a control method of the boiler water supply system, in which the lowering of the water level of the drum can be suppressed.
　本発明の第１態様は、ボイラの蒸気ドラム内のボイラ水と熱交換させた水を、火炉からの排ガスと熱交換する給水加熱用エコノマイザに供給する経路である第１経路と、前記ボイラ水と熱交換させる前の前記第１経路から分岐し、前記蒸気ドラムをバイパスして前記給水加熱用エコノマイザの入口側の合流点で前記第１経路と合流する第２経路と、前記第２経路から分岐し、前記蒸気ドラムに給水する第３経路とを備える給水系統と、前記合流点と前記給水加熱用エコノマイザとの間の水温を検出する温度検出手段と、前記第１経路と前記第２経路と前記第３経路とに流れる水の流量を調整する流量調整手段と、前記温度検出手段で検出される前記水温が、前記給水加熱用エコノマイザの低温腐食を防ぐ所定温度以上となるように、前記流量調整手段を調整する制御手段と、を具備するボイラ給水システムである。 According to a first aspect of the present invention, there is provided a first path, which is a path for supplying water supplied to a feed water heating economizer that exchanges heat with boiler water in a steam drum of a boiler with heat exhaust gas from a furnace; And a second route which branches from the first route before heat exchange and bypasses the steam drum and merges with the first route at a junction on the inlet side of the feed water heating economizer, and the second route A water supply system including a third path branched and supplying water to the steam drum, temperature detection means for detecting a water temperature between the junction and the economizer for water supply heating, the first path and the second path Flow rate adjusting means for adjusting the flow rate of water flowing through the third path and the water temperature detected by the temperature detecting means so that the water temperature detected by the temperature detecting means is equal to or higher than a predetermined temperature for preventing low temperature corrosion of the feedwater heating economizer Flow And control means for adjusting the adjustment means is a boiler water supply system having a.
　本発明の第１態様によれば、第１経路を流通する水は、蒸気ドラム内のボイラ水と熱交換されて加熱される。このように、従来から備えられるボイラの蒸気ドラム内のボイラ水の保有熱を用いて給水を加熱することにより、給水加熱用エコノマイザに流入する給水温度を、低温腐食を防ぐ所定温度以上となるように調整、維持できる。また、蒸気ドラム内のドラム水と熱交換させるので、大掛かりな別置きの給水加熱装置（例えば、デアレータ（脱気器））が不要となり、配置スペースを余分に使用することがない。 According to the first aspect of the present invention, the water flowing through the first path is heated by heat exchange with the boiler water in the steam drum. Thus, by heating the feed water using the stored heat of the boiler water in the steam drum of the conventionally equipped boiler, the feed water temperature flowing into the feed water heating economizer becomes equal to or higher than the predetermined temperature which prevents low temperature corrosion Can be adjusted and maintained. Further, since heat exchange is performed with the drum water in the steam drum, a large-scale separate feed water heating device (for example, a deaerator) is not necessary, and an extra arrangement space is not used.
　そして、第１経路と第２経路と第３経路とに流れる水の流量を調整する流量調整手段と、給水加熱用エコノマイザに流入する給水温度を検出する温度検出手段を用いて、以下のように給水加熱用エコノマイザに流入する給水温度を調整することができる。すなわち、第２経路と第３経路の水の流量が調整され、第２経路に水を流通させ第３経路に水を流通させなければ、ボイラ水によって加熱された第１経路の水は、第２経路によって蒸気ドラムをバイパスされた未加熱の水と合流され、温度が下げられる。このように、給水加熱用エコノマイザに流入する給水温度を下げて所定温度に近づけることができるので、加熱媒体である燃焼排ガスとの温度差を大きく確保することにより、給水加熱用エコノマイザにおける熱回収効率を向上させることができる。 And, using the flow rate adjusting means for adjusting the flow rate of water flowing to the first path, the second path and the third path, and the temperature detecting means for detecting the temperature of the feedwater flowing into the feedwater heating economizer as follows: The feedwater temperature flowing into the feedwater heating economizer can be adjusted. That is, if the flow rate of water in the second and third paths is adjusted and water is circulated in the second path and water is not circulated in the third path, the water in the first path heated by the boiler water is The two paths merge with the unheated water bypassing the steam drum and the temperature is lowered. As described above, since the temperature of the feed water flowing into the feed water heating economizer can be lowered to approach the predetermined temperature, the heat recovery efficiency of the feed water heating economizer can be achieved by securing a large temperature difference with the combustion exhaust gas as the heating medium. Can be improved.
　一方、第２経路と第３経路の水の流量が調整され、第２経路に水を流通させず第３経路に水を流通させれば、第３経路から蒸気ドラムに給水される水量が増加することによって相対的に第１経路の流量が減るので、ボイラ水によって加熱された水は高温となって温度が上げられる。また、第２経路から導かれた水で第１経路を流通した水の温度が下げられることがない。 On the other hand, if the flow rate of water in the second and third paths is adjusted, and water is circulated in the third path without flowing water in the second path, the amount of water supplied to the steam drum from the third path increases. By doing so, the flow rate of the first path is relatively reduced, so the water heated by the boiler water becomes hot and the temperature is raised. In addition, the temperature of the water flowing through the first route can not be lowered by the water led from the second route.
　本発明の第１態様の上記ボイラ給水システムの前記第１経路は、前記蒸気ドラム内のボイラ水中に設けられる伝熱管に給水し、前記伝熱管内の水と前記蒸気ドラム内の前記ボイラ水とを熱交換することとしてもよい。 The first path of the boiler water supply system according to the first aspect of the present invention supplies water to a heat transfer pipe provided in boiler water in the steam drum, and water in the heat transfer pipe and the boiler water in the steam drum The heat may be exchanged.
　ボイラ水中に設けられた伝熱管が給水を加熱する加熱器となり、伝熱管を用いて給水を加熱するので、蒸気ドラム内のボイラ水を抜き出す技術に比べて水位の低下を来すことがない。これにより、安定した蒸気圧力を蒸気ドラムから出力することができ、また過剰な水位低下による空焚きを回避することができる。 Since the heat transfer pipe provided in the boiler water serves as a heater for heating the feed water and heats the feed water using the heat transfer pipe, the water level does not fall compared to the technique for extracting the boiler water in the steam drum. As a result, stable steam pressure can be output from the steam drum, and it is possible to avoid airing due to excessive water level drop.
　本発明の第１態様の上記ボイラ給水システムの前記ボイラは、補助ボイラとしてもよい。
　本発明の第１態様により、補助ボイラに設けられる給水加熱用エコノマイザに対して、低温腐食を防止することができる。特に、主ボイラに比べて蒸気圧力が低い補助ボイラでは、デアレータを設置する必要性が低いので特に有益である。 The boiler of the boiler water supply system according to the first aspect of the present invention may be an auxiliary boiler.
According to the first aspect of the present invention, low temperature corrosion can be prevented with respect to the feed water heating economizer provided in the auxiliary boiler. In particular, an auxiliary boiler having a lower steam pressure than the main boiler is particularly useful because it is less necessary to install a deaerator.
　本発明の第１態様の上記ボイラ給水システムは、前記温度検出手段により検出された温度が前記所定温度より小さい場合に、前記第２経路を閉状態とし、前記第１経路と前記第３経路とに流れる水の流量を調整してもよい。 In the boiler water supply system according to the first aspect of the present invention, the second path is closed when the temperature detected by the temperature detection means is lower than the predetermined temperature, and the first path and the third path The flow rate of water flowing to the
　本発明の第１態様により、給水加熱用エコノマイザに給水される水温が所定温度より小さい場合に、第２経路を閉状態にすることで、第１経路を流通した水の温度が下げられることがなく、かつ、第１経路に流通させる水量が調整されることで、水温を上げる方向に制御できる。 According to the first aspect of the present invention, when the water temperature supplied to the feed water heating economizer is smaller than the predetermined temperature, the temperature of the water flowing through the first path can be lowered by closing the second path. In addition, by adjusting the amount of water circulated in the first route, it is possible to control the water temperature to increase.
　本発明の第１態様の上記ボイラ給水システムは、前記温度検出手段により検出された温度が前記所定温度より所定値以上大きくなった場合に、前記第３経路を閉状態とし、前記第１経路と前記第２経路とに流れる水の流量を調整してもよい。 In the boiler water supply system according to the first aspect of the present invention, the third path is closed when the temperature detected by the temperature detection means exceeds the predetermined temperature by a predetermined value or more. The flow rate of water flowing to the second path may be adjusted.
　本発明の第１態様により、給水加熱用エコノマイザに給水される水温が所定温度より所定値以上大きくなった場合に、第２経路を開状態とすることで第１経路を流通した水の温度を下げることができ、水温を下げる方向に制御できる。このように、給水加熱用エコノマイザに給水される水温を下げる制御を行うときの閾値を所定温度から所定値以上大きい温度として、所定温度から一定の許容範囲を持たせることにより、流量調整手段における流量制御が頻繁に切り替えられることを防ぐことができる。 According to the first aspect of the present invention, when the water temperature supplied to the feed water heating economizer is higher than the predetermined temperature by a predetermined value or more, the temperature of the water flowing through the first route is set by opening the second route. It can be lowered and controlled to lower the water temperature. Thus, the flow rate in the flow rate adjusting means is set by setting the threshold value when performing control to lower the water temperature supplied to the feed water heating economizer as a temperature larger than the predetermined temperature by the predetermined value or more from the predetermined temperature. Control can be prevented from being switched frequently.
　本発明の第２態様は、上記いずれかに記載のボイラ給水システムを具備するボイラである。 A second aspect of the present invention is a boiler including the boiler water supply system according to any one of the above.
　本発明の第３態様は、ボイラの蒸気ドラム内のボイラ水と熱交換させた水を、火炉からの排ガスと熱交換する給水加熱用エコノマイザに供給する経路である第１経路と、前記ボイラ水と熱交換させる前の前記第１経路から分岐し、前記蒸気ドラムをバイパスして前記給水加熱用エコノマイザの入口側の合流点で前記第１経路と合流する第２経路と、前記第２経路から分岐し、前記蒸気ドラムに給水する第３経路とを備える給水系統を具備するボイラ給水システムの制御方法であって、前記合流点と前記給水加熱用エコノマイザとの間の水温を検出し、前記水温が、前記給水加熱用エコノマイザの低温腐食を防ぐ所定温度以上となるように、前記第１経路と前記第２経路と前記第３経路とに流れる水の流量を調整するボイラ給水システムの制御方法である。 According to a third aspect of the present invention, there is provided a first path which is a path for supplying water supplied to a feed water heating economizer which exchanges heat with boiler water in a steam drum of a boiler with exhaust gas from a furnace, and the boiler water And a second route which branches from the first route before heat exchange and bypasses the steam drum and merges with the first route at a junction on the inlet side of the feed water heating economizer, and the second route A control method for a boiler water supply system comprising a water supply system including a third path branched and supplying water to the steam drum, wherein a water temperature between the junction and the water supply heating economizer is detected, and the water temperature is detected. Control of a boiler water supply system for adjusting the flow rate of water flowing in the first path, the second path and the third path so that the temperature is equal to or higher than a predetermined temperature that prevents low temperature corrosion of the feed water heating economizer It is a method.
　本発明は、給水加熱装置の低温腐食を防止し、かつ、省スペースでコスト低減を図ることができる。また、本発明は、ドラムの水位低下が抑えられるという効果を奏する。 The present invention can prevent low temperature corrosion of the feed water heating device, and can achieve cost reduction with space saving. Further, the present invention has an effect that the water level drop of the drum can be suppressed.
本発明に係る舶用排熱回収システムの概略構成図である。It is a schematic block diagram of the marine exhaust heat recovery system concerning the present invention. 本発明に係るボイラ給水システムの概略構成図である。It is a schematic block diagram of the boiler feed water system concerning the present invention. 蒸気によって駆動される蒸気駆動機器に与えられる指令が変化した場合の各パラメータの変化を示した説明図である。It is an explanatory view showing change of each parameter when a command given to a steam drive apparatus driven by steam changes. 第１経路と第３経路に流通させる水の流量割合を示すグラフである。It is a graph which shows the flow rate ratio of the water circulated through the 1st course and the 3rd course. 第１経路と第２経路に流通させる水の流量割合を示すグラフである。It is a graph which shows the flow rate ratio of the water circulated through the 1st course and the 2nd course.
　以下に、本発明に係るボイラ給水システム及びそれを備えたボイラ、並びにボイラ給水システムの制御方法の実施形態について、図面を参照して説明する。なお、実施形態の説明においては、本発明に係るボイラ給水システムは、例えば、タンカー船等の舶用補助ボイラ（以下、「補助ボイラ」という）に適用されるものとして説明するが、これに限定されない。 EMBODIMENT OF THE INVENTION Below, the boiler water supply system which concerns on this invention, the boiler provided with the same, and embodiment of the control method of a boiler water supply system are described with reference to drawings. In addition, in description of embodiment, although the boiler water supply system which concerns on this invention is demonstrated as what is applied to marine auxiliary boilers (henceforth "an auxiliary boiler"), such as a tanker ship, it is not limited to this .
　図１は、本実施形態のボイラ給水システムを備えた舶用排熱回収システム１の概略構成を示している。
　図１に示されるように、本実施形態の舶用排熱回収システム１は、主機関３と、排熱回収機構４と、補助ボイラ１０と、給水加熱用エコノマイザ２とを備える。
　主機関３は、船舶の推進機関であり、例えば、ディーゼルエンジンまたは主ボイラが用いられる。主機関３は図示しない駆動軸を駆動することによって、駆動軸に設けられた図示しないプロペラを回転させる。主機関３からの排ガスは排気管６を経由して排熱回収機構４に導かれる。 FIG. 1 shows a schematic configuration of a marine exhaust heat recovery system 1 provided with a boiler water supply system according to the present embodiment.
As shown in FIG. 1, the marine exhaust heat recovery system 1 of the present embodiment includes a main engine 3, an exhaust heat recovery mechanism 4, an auxiliary boiler 10, and a feedwater heating economizer 2.
The main engine 3 is a ship propulsion engine, and for example, a diesel engine or a main boiler is used. The main engine 3 rotates a propeller (not shown) provided on the drive shaft by driving a drive shaft (not shown). Exhaust gas from the main engine 3 is led to an exhaust heat recovery mechanism 4 via an exhaust pipe 6.
　排熱回収機構４は、例えば、排ガスエコノマイザが用いられる。排熱回収機構４は、主機関３の排ガスを利用して蒸気を生成し、生成した蒸気は雑用蒸気として図示しない蒸気タービン等に供給する。排熱回収機構４において、熱交換を行った排ガスは、煙突５から系外に排出される。 For example, an exhaust gas economizer is used as the exhaust heat recovery mechanism 4. The exhaust heat recovery mechanism 4 generates steam using the exhaust gas of the main engine 3 and supplies the generated steam as a miscellaneous steam to a steam turbine (not shown) or the like. The exhaust gas subjected to heat exchange in the exhaust heat recovery mechanism 4 is discharged from the chimney 5 to the outside of the system.
　補助ボイラ１０は、蒸気ドラム１１を備えており、燃料を燃焼することで蒸気を生成する。この補助ボイラ１０は、船舶に搭載され、船舶内の温熱需要に応えるボイラである。補助ボイラ１０は、自然循環型または強制循環型とされたボイラとされる。 The auxiliary boiler 10 includes a steam drum 11, and generates steam by burning a fuel. The auxiliary boiler 10 is a boiler that is mounted on a ship and responds to the heat demand in the ship. The auxiliary boiler 10 is a natural circulation type or a forced circulation type boiler.
　蒸気ドラム１１は、補助ボイラ１０にて得られた蒸気を貯留するドラム（汽水ドラム）である。蒸気ドラム１１の上方空間は蒸気が占有し、その下方にはボイラ水が貯留される。また、補助ボイラ１０の蒸気圧力は、０．２ＭＰａ以上６ＭＰａ以下であり、典型的には２ＭＰａ以下とする。本実施形態における蒸気ドラム１１内の水温は、補助ボイラ１０の蒸気圧力が２ＭＰａの場合、約２１０℃となる。補助ボイラ１０は、船舶内の蒸気駆動機器７（例えば、原油荷揚げ用ポンプ（カーゴオイルポンプ）を駆動するカーゴオイルポンプタービン（ＣＯＰＴ：Ｃａｒｇｏ　Ｏｉｌ　Ｐｕｍｐ　Ｔｕｒｂｉｎｅ）等）の動力源や加熱媒体として利用される他、厨房用の温水暖房とイナートガスの生成等に利用される。 The steam drum 11 is a drum (boiling water drum) that stores the steam obtained by the auxiliary boiler 10. The space above the steam drum 11 is occupied by steam, and the boiler water is stored below the space. Further, the steam pressure of the auxiliary boiler 10 is 0.2 MPa or more and 6 MPa or less, and typically 2 MPa or less. The water temperature in the steam drum 11 in the present embodiment is about 210 ° C. when the steam pressure of the auxiliary boiler 10 is 2 MPa. The auxiliary boiler 10 is used as a power source and heating medium for a steam drive device 7 (for example, a cargo oil pump turbine (COPT: Cargo Oil Pump Turbine) that drives a crude oil unloading pump (cargo oil pump) etc.) in a ship. It is also used for hot water heating for kitchens and generation of inert gas.
　給水加熱用エコノマイザ２には、給水の経路である給水系統２１が接続されている。給水加熱用エコノマイザ２は、給水された水を補助ボイラ（ボイラ）１０から排出された排ガスと熱交換させて加熱し、蒸気ドラム１１に加熱した水を供給する。 A water supply system 21 which is a water supply path is connected to the water supply heating economizer 2. The feed water heating economizer 2 heats the water supplied to the steam drum 11 by exchanging heat with the exhaust gas discharged from the auxiliary boiler (boiler) 10, and supplies the heated water to the steam drum 11.
　図２に示されるように、ボイラ給水システム２０は、給水系統２１と、蒸気ドラム１１内に設けられた加熱器２３と、温度検出部（温度検出手段）２４と、流量調整部（流量調整手段）２５と、制御部（制御手段）２６と、ボイラ給水経路２７とを備えている。なお、図２は、図１と異なり、蒸気ドラム１１に対して給水加熱用エコノマイザ２が下方に位置しているが、これは給水系統２１を分かり易く示すために実際の配置の上下関係を無視して便宜的に示されたものである。したがって、一般に、給水加熱用エコノマイザ２は、蒸気ドラム１１の上方に位置する。 As shown in FIG. 2, the boiler water supply system 20 includes a water supply system 21, a heater 23 provided in the steam drum 11, a temperature detection unit (temperature detection means) 24, and a flow rate adjustment unit (flow rate adjustment means). ), A control unit (control means) 26, and a boiler water supply path 27. 2 differs from FIG. 1 in that the feed water heating economizer 2 is positioned below the steam drum 11. However, in order to clearly show the feed water system 21, this ignores the vertical relationship of the actual arrangement. For the sake of convenience. Therefore, in general, the feed water heating economizer 2 is located above the steam drum 11.
　給水系統２１は、第１経路２１ａと、第２経路２１ｂと、第３経路２１ｃとを備える。
　第１経路２１ａは、補助ボイラ１０の蒸気ドラム１１内のボイラ水と熱交換させた水を、火炉からの排ガスと熱交換する給水加熱用エコノマイザ２に供給する経路である。本実施形態においては、第１経路２１ａは、蒸気ドラム１１に給水する経路２１ａ１と、加熱器２３を構成する伝熱管２１ａ２と、蒸気ドラム１１から給水加熱用エコノマイザ２に給水する経路２１ａ３とを備える。
　第１経路２１ａは、補助ボイラ１０の蒸気ドラム１１内のボイラ水中１２に設けられる伝熱管２１ａ２に給水し、ボイラ水と熱交換させた水を給水加熱用エコノマイザ２に供給する経路である。給水源から供給される経路２１ａ１の給水温度は、例えば、６０℃から８０℃であり、蒸気ドラム１１内の水温より低い温度の水が給水される。 The water supply system 21 includes a first path 21a, a second path 21b, and a third path 21c.
The first path 21a is a path for supplying water, which has been heat-exchanged with the boiler water in the steam drum 11 of the auxiliary boiler 10, to the feedwater heating economizer 2 which exchanges heat with the exhaust gas from the furnace. In the present embodiment, the first path 21a includes a path 21a1 for supplying water to the steam drum 11, a heat transfer pipe 21a2 constituting the heater 23, and a path 21a3 for supplying water from the steam drum 11 to the feed water heating economizer 2 .
The first path 21 a is a path for supplying water to the heat transfer pipe 21 a 2 provided in the boiler water 12 in the steam drum 11 of the auxiliary boiler 10 and supplying the water heat-exchanged with the boiler water to the feed water heating economizer 2. The water supply temperature of the path 21a1 supplied from the water supply source is, for example, 60 ° C. to 80 ° C., and water having a temperature lower than the water temperature in the steam drum 11 is supplied.
　第２経路２１ｂは、経路２１ｂ１と経路２１ｂ２と流量調整部２５とを備える。
　第２経路２１ｂは、ボイラ水中の伝熱管２１ａ２に給水させる入口側の第１経路２１ａの経路２１ａ１から分岐し、蒸気ドラム１１をバイパスして給水加熱用エコノマイザ２の入口側の合流点Ｘで第１経路２１ａの経路２１ａ３と合流するまでの経路である。第２経路２１ｂは、第１経路２１ａの経路２１ａ１から分岐する分岐点Ｚと合流点Ｘとの間に流量調整部２５が設けられる。経路２１ｂ１は、分岐点Ｚから流量調整部２５までの経路であり、経路２１ｂ２は、流量調整部２５から合流点Ｘまでの経路である。 The second path 21 b includes a path 21 b 1, a path 21 b 2, and a flow rate adjustment unit 25.
The second path 21b branches from the path 21a1 of the first path 21a on the inlet side for supplying water to the heat transfer pipe 21a2 in the boiler water, bypasses the steam drum 11, and merges at the junction X on the inlet side of the feedwater heating economizer 2 It is a route until it merges with the route 21a3 of the first route 21a. In the second path 21b, the flow rate adjusting unit 25 is provided between the junction point X and the branch point Z branched from the path 21a1 of the first path 21a. The path 21 b 1 is a path from the branch point Z to the flow rate adjustment unit 25, and the path 21 b 2 is a path from the flow rate adjustment unit 25 to the junction point X.
　第３経路２１ｃは、経路２１ｂ１と経路２１ｂ２とを接続する流量調整部２５を介して第２経路２１ｂから分岐し、ボイラ給水経路２７との合流点Ｙで合流して、蒸気ドラム１１に給水する。
　ボイラ給水経路２７は、給水加熱用エコノマイザ２で熱交換された水を蒸気ドラム１１に供給する。
　なお、本実施形態において、第３経路２１ｃがボイラ給水経路２７と合流して蒸気ドラムに給水しているが、これに限定されず、第３経路２１ｃとボイラ給水経路２７とがそれぞれ別々の経路で蒸気ドラム１１に給水してもよい。 The third path 21c branches from the second path 21b via the flow rate adjustment unit 25 connecting the path 21b1 and the path 21b2, joins at the junction point Y with the boiler water supply path 27, and supplies water to the steam drum 11. .
The boiler feed water path 27 supplies the water heat-exchanged by the feed water heating economizer 2 to the steam drum 11.
In the present embodiment, the third path 21c merges with the boiler water supply path 27 and supplies water to the steam drum. However, the present invention is not limited thereto. The third path 21c and the boiler water supply path 27 are separate paths. The steam drum 11 may be supplied with water.
　加熱器２３は、蒸気ドラム１１のボイラ水中１２に伝熱管２１ａ２を通し、伝熱管２１ａ２に流通する水を加熱する。これにより、蒸気ドラム１１内のボイラ水が保有する顕熱を用いて給水が加熱されるようになっている。
　このように、蒸気ドラム１１内のボイラ水中１２の伝熱管２１ａ２内で、（伝熱管２１ａ２の外側の）蒸気ドラム１１内のボイラ水と伝熱管２１ａ２内の水とを熱交換して加熱する間接式熱交換を採用している。このため、ボイラ水を蒸気ドラムから抜き出して給水の水温度の調整に使用する技術とは異なり、ボイラ水の水位の変動を可及的に防止できるようになっている。 The heater 23 passes the heat transfer pipe 21a2 through the boiler water 12 of the steam drum 11, and heats the water flowing through the heat transfer pipe 21a2. Thereby, the feed water is heated using the sensible heat which the boiler water in the steam drum 11 holds.
In this manner, in the heat transfer pipe 21a2 of the boiler water 12 in the steam drum 11, heat is exchanged between the boiler water in the steam drum 11 (outside of the heat transfer pipe 21a2) and the water in the heat transfer pipe 21a2 to heat it indirectly Heat exchange is adopted. For this reason, unlike the technique of extracting boiler water from a steam drum and using it for adjustment of the water temperature of feed water, fluctuation of the water level of the boiler water can be prevented as much as possible.
　温度検出部２４は、合流点Ｘと給水加熱用エコノマイザ２との間の水温を検出し、検出された水温の情報を制御部２６に出力する。温度検出部２４は、例えば、熱電対等の温度センサである。 The temperature detection unit 24 detects the water temperature between the junction point X and the feed water heating economizer 2, and outputs information on the detected water temperature to the control unit 26. The temperature detection unit 24 is, for example, a temperature sensor such as a thermocouple.
　流量調整部２５は、第１経路２１ａと第２経路２１ｂと第３経路２１ｃとに流れる水の流量を調整する。流量調整部２５は、例えば、三方弁（制御弁）とし、第１経路２１ａから分岐された第２経路２１ｂにおいて、経路２１ｂ１から、経路２１ｂ２と第３経路２１ｃとの分岐点に設ける。また、流量調整部２５は三方弁に限られず、第２経路２１ｂと第３経路２１ｃのそれぞれに二方弁（制御弁）を設け、それぞれの二方弁を制御することにより各経路に流通する水の流量を調整してもよい。 The flow rate adjustment unit 25 adjusts the flow rate of water flowing through the first path 21a, the second path 21b, and the third path 21c. The flow rate adjustment unit 25 is, for example, a three-way valve (control valve), and is provided at a branch point between the path 21b1 and the path 21b2 and the third path 21c in the second path 21b branched from the first path 21a. Further, the flow rate adjusting unit 25 is not limited to the three-way valve, but two-way valves (control valves) are provided in each of the second path 21b and the third path 21c, and flow is made in each path by controlling each two-way valve. The flow rate of water may be adjusted.
　制御部２６は、温度検出部２４で検出される水温が、給水加熱用エコノマイザ２の低温腐食を防ぐ所定温度（例えば、１３５℃）以上となるように、流量調整部２５を調整する。給水加熱用エコノマイザ２の低温腐食を防ぐ温度の下限値としては、燃料中の硫黄濃度等によって変化するが、例えば、１３５℃が用いられる。
　制御部２６による流量調整部２５の調整では、第１経路２１ａ及び第３経路２１ｃに水を流通させた場合には、第２経路２１ｂの経路２１ｂ２には水を流通させず、第１経路２１ａ及び第２経路２１ｂ（経路２１ｂ１及び経路２１ｂ２）に水を流通させた場合には、第３経路２１ｃには水を流通させない。つまり、第２経路２１ｂの経路２１ｂ２と、第３経路２１ｃとに同時に水を流すことはない。 The control unit 26 adjusts the flow rate adjusting unit 25 so that the water temperature detected by the temperature detection unit 24 is equal to or higher than a predetermined temperature (for example, 135 ° C.) that prevents low temperature corrosion of the feedwater heating economizer 2. As a lower limit value of temperature which prevents low temperature corrosion of economizer 2 for feed water heating, although it changes with sulfur concentration etc. in fuel, 135 ° C is used, for example.
In the adjustment of the flow rate adjustment unit 25 by the control unit 26, when water is circulated in the first path 21a and the third path 21c, the water is not circulated in the path 21b2 of the second path 21b, and the first path 21a And when water is distribute | circulated to 2nd path | route 21b (path | route 21 b1 and path | route 21 b2), water is not distribute | circulated to the 3rd path | route 21 c. That is, water does not flow simultaneously to the path 21b2 of the second path 21b and the third path 21c.
　第１経路２１ａと経路２１ｂ１と第３経路２１ｃとに水を流通させる場合、或いは、第１経路２１ａと第２経路２１ｂ（経路２１ｂ１及び経路２１ｂ２）に水を流通させる場合における、それぞれの経路に流通させる水量の比率は、温度検出部２４で所望の温度が得られるために適宜任意に調整されるものとする。例えば、事前試験等によって、各経路に所定割合で給水された場合の蒸気ドラム１１出口の水温Ｔｏｕｔの変化の情報をテーブル等で得ておき、これに基づいて決定される。 When water is caused to flow through the first route 21a, the route 21b1 and the third route 21c, or when water is caused to flow through the first route 21a and the second route 21b (the route 21b1 and the route 21b2), The ratio of the amount of water to be circulated is appropriately adjusted arbitrarily in order to obtain a desired temperature in the temperature detection unit 24. For example, information on the change in the water temperature Tout at the outlet of the steam drum 11 when water is supplied to each path at a predetermined rate by a preliminary test or the like is obtained based on a table or the like.
　次に、図３を用いて、伝熱管２１ａ２の蒸気ドラム１１の出口の水の温度である水温Ｔｏｕｔの変動について説明する。図３には、蒸気ドラム１１から供給された蒸気によって動作するプラントである蒸気駆動機器７に与えられる指令が変化した場合の各パラメータの変化が示されている。制御部２６から、蒸気駆動機器７の負荷を変化する指令が入力されると、負荷変化に対応する蒸気ドラム１１における蒸気発生量が変化する。蒸気ドラム１１内の蒸気発生量が変化すると、蒸気ドラム１１内の蒸気圧力が変化する。
　水温Ｔｏｕｔが変化する要因としては、蒸気発生量の変化が挙げられる。 Next, the fluctuation of the water temperature Tout, which is the temperature of the water at the outlet of the steam drum 11 of the heat transfer tube 21a2, will be described with reference to FIG. FIG. 3 shows changes in the respective parameters when the command given to the steam driving device 7 which is a plant operated by the steam supplied from the steam drum 11 changes. When a command to change the load of the steam driving device 7 is input from the control unit 26, the amount of generated steam in the steam drum 11 corresponding to the change in load changes. When the amount of steam generated in the steam drum 11 changes, the steam pressure in the steam drum 11 changes.
A factor that changes the water temperature Tout is a change in the amount of steam generation.
　蒸気ドラム１１における蒸気発生量が変化すると、蒸気発生量の変化に見合う給水流量が変化して、結果として水温Ｔｏｕｔが変化する。具体的には、蒸気駆動機器７の負荷が増えると、負荷増大分に相当する発生蒸気量が増え、この蒸気発生量の増大分に見合うように給水流量が増大する。給水流量が増大すると、熱交換器に相当する伝熱管２１ａ２で加熱しなければならない水量が増加するので、水温Ｔｏｕｔが下がる。蒸気駆動機器７の負荷が減少した場合は、この逆の動きとなる。 When the steam generation amount in the steam drum 11 changes, the feed water flow rate corresponding to the change in the steam generation amount changes, and as a result, the water temperature Tout changes. Specifically, when the load on the steam driving device 7 increases, the amount of generated steam corresponding to the increase in load increases, and the feed water flow rate increases to meet the increase in the amount of steam generation. When the feed water flow rate increases, the amount of water that needs to be heated by the heat transfer pipe 21a2 corresponding to the heat exchanger increases, so the water temperature Tout decreases. When the load of the steam drive device 7 decreases, the opposite action occurs.
　なお、発生蒸気量が変化すると、蒸気ドラム１１内の蒸気圧力が変化し、定格圧力に復帰するように補助ボイラ１０に投入される燃料量が変化する。具体的には、蒸気駆動機器７の負荷が増えて、要求される発生蒸気量が増えると、多くの蒸気が蒸気ドラム１１内から外部の蒸気駆動機器７へと持ち出されることになるため、蒸気ドラム１１内の圧力が一時的に減少する。そして、一時的に減少した蒸気ドラム１１内の圧力を増大させて定格圧力に復帰させるため、補助ボイラ１０に投入される燃料量が増大される。蒸気駆動機器７の負荷が減少した場合は、この逆の動きとなる。 When the amount of generated steam changes, the steam pressure in the steam drum 11 changes, and the amount of fuel input to the auxiliary boiler 10 changes so as to return to the rated pressure. Specifically, if the load of the steam driving device 7 increases and the required amount of generated steam increases, a large amount of steam will be carried out from the inside of the steam drum 11 to the external steam driving device 7. The pressure in the drum 11 is temporarily reduced. Then, the pressure in the steam drum 11 which has temporarily decreased is increased to return to the rated pressure, so the amount of fuel input to the auxiliary boiler 10 is increased. When the load of the steam drive device 7 decreases, the opposite action occurs.
　このように水温Ｔｏｕｔの温度変化が生じ得るので、温度検出部２４で計測される水温が、給水加熱用エコノマイザ２の低温腐食を防ぐ所定温度（例えば、１３５℃）以上となるように、給水系統２１を流通する水の流量を調整させる。 Thus, since the temperature change of the water temperature Tout may occur, the water supply system is performed so that the water temperature measured by the temperature detection unit 24 is equal to or higher than a predetermined temperature (for example, 135 ° C.) that prevents low temperature corrosion of the economizer 2 for water supply heating. Adjust the flow rate of water flowing through 21.
　温度検出部２４で検出された温度が所定温度より小さい場合に、第２経路２１ｂの経路２１ｂ２を閉状態とし、第２経路２１ｂの経路２１ｂ１と第３経路２１ｃとを開状態として、経路２１ｂ２と第３経路２１ｃとに流れる水の流量を調整する。これにより、第２経路２１ｂの経路２１ｂ２から導かれた水で第１経路２１ａを流通した水の温度が下げられることないので、水温を上げる方向に制御できる。 When the temperature detected by the temperature detection unit 24 is lower than the predetermined temperature, the path 21b2 of the second path 21b is closed, and the path 21b1 of the second path 21b and the third path 21c are open. The flow rate of water flowing to the third path 21c is adjusted. Thus, the temperature of the water flowing through the first path 21a is not lowered by the water led from the path 21b2 of the second path 21b, so that the water temperature can be controlled to be increased.
　また、温度検出部２４により検出された温度が所定温度（例えば、１３５℃）より大きくなった場合に、第２経路２１ｂの経路２１ｂ２を開状態とし、第３経路２１ｃを閉状態として、第２経路２１ｂ（経路２１ｂ１及び経路２１ｂ２）と第３経路２１ｃとに流れる水の流量を調整する。これにより、第１経路２１ａを流通した水の温度を下げる方向に制御できる。 Also, when the temperature detected by the temperature detection unit 24 becomes higher than a predetermined temperature (for example, 135 ° C.), the second path 21 b is opened and the third path 21 c is closed. The flow rate of water flowing through the path 21b (path 21b1 and path 21b2) and the third path 21c is adjusted. Thus, the temperature of the water flowing through the first path 21a can be controlled to be lowered.
　図４及び図５には、温度検出部２４により検出された温度と目標温度（所定温度）である１３５℃との差に応じた流量制御が示されている。
　図４（ａ）の縦軸は温度を示し、図４（ｂ）の縦軸は第１経路２１ａの流量と第２経路２１ｂの経路２１ｂ２の流量の割合を示している。
　図４（ａ）のように目標温度である１３５℃に対して、破線で示した検出温度が高い場合には、これらの温度差が大きいほど（同図において右側に行くほど）、温度検出部２４により検出される温度を所定温度に近づけるために、図４（ｂ）に示すように第１経路２１ａの流量に対する第２経路２１ｂの経路２１ｂ２の流量の割合を増大させる。このように、第１経路２１ａと第２経路２１ｂの経路２１ｂ２との流量割合を検出温度と目標温度との温度差に応じて適宜調整することによって、給水加熱用エコノマイザ２に流入する給水温度を下げることができる。 FIGS. 4 and 5 show flow control in accordance with the difference between the temperature detected by the temperature detection unit 24 and 135 ° C. which is the target temperature (predetermined temperature).
The vertical axis in FIG. 4A indicates the temperature, and the vertical axis in FIG. 4B indicates the ratio of the flow rate of the first path 21a to the flow rate of the path 21b2 of the second path 21b.
As shown in FIG. 4A, when the detected temperature indicated by the broken line is higher than the target temperature of 135 ° C., the larger the temperature difference is (the closer to the right in the figure), the temperature detection unit In order to bring the temperature detected by the sensor 24 close to the predetermined temperature, the ratio of the flow rate of the path 21b2 of the second path 21b to the flow rate of the first path 21a is increased as shown in FIG. Thus, the feedwater temperature flowing into the feedwater heating economizer 2 is adjusted by appropriately adjusting the flow rate ratio between the first path 21a and the path 21b2 of the second path 21b according to the temperature difference between the detected temperature and the target temperature. It can be lowered.
　一方、図５（ａ）のように目標温度である１３５℃に対して、破線で示した検出温度が低い場合には、これらの温度差が大きいほど（同図において右側に行くほど）、温度検出部２４により検出される温度を所定温度に近づけるために、図５（ｂ）に示すように第１経路２１ａの流量に対する経路２１ｂ１及び第３経路２１ｃの流量の割合を増大させる。このように、第１経路２１ａと第３経路２１ｃの流量割合を検出温度と目標温度との温度差に応じて適宜調整することによって、給水加熱用エコノマイザ２に流入する給水温度を上げることができる。 On the other hand, when the detected temperature indicated by the broken line is lower than the target temperature of 135 ° C. as shown in FIG. 5A, the larger the temperature difference (the closer to the right in the figure), In order to bring the temperature detected by the detection unit 24 closer to the predetermined temperature, the ratio of the flow rate of the path 21b1 and the third path 21c to the flow rate of the first path 21a is increased as shown in FIG. Thus, the feedwater temperature flowing into the feedwater heating economizer 2 can be increased by appropriately adjusting the flow rate ratio of the first path 21a and the third path 21c according to the temperature difference between the detected temperature and the target temperature. .
　以上説明してきたように、本実施形態に係るボイラ給水システム２０及びそれを備えた補助ボイラ１０、並びにボイラ給水システム２０の制御方法によれば、第１経路２１ａを流通する水は、蒸気ドラム１１内のボイラ水中１２に設けられる伝熱管２１ａ２で、蒸気ドラム１１内の水と熱交換されて加熱される。すなわち、ボイラ水中１２に設けられた伝熱管２１ａ２が給水を加熱する加熱器２３となる。このように、従来から備えられるボイラの蒸気ドラム１１内のボイラ水の保有熱を用いて給水を加熱することにより、給水加熱用エコノマイザ２に流入する給水を、低温腐食を防ぐ所定温度以上に維持することができる。また、伝熱管２１ａ２を用いて給水を加熱することとしたので、蒸気ドラム１１内のボイラ水を抜き出す技術に比べて、水位の低下を来すことがない。これにより、安定した蒸気圧力でボイラを運転することができ、また過剰な水位低下による空焚きを回避することができる。 As described above, according to the boiler water supply system 20 according to the present embodiment, the auxiliary boiler 10 including the same, and the control method of the boiler water supply system 20, the water flowing through the first path 21 a is the steam drum 11. Heat is exchanged with the water in the steam drum 11 and heated in a heat transfer pipe 21a2 provided in the boiler water 12 inside. That is, the heat transfer pipe 21a2 provided in the boiler water 12 serves as the heater 23 for heating the feed water. Thus, the feed water flowing into the feed water heating economizer 2 is maintained at a predetermined temperature or more to prevent low temperature corrosion by heating the feed water using the stored heat of the boiler water in the steam drum 11 of the conventionally equipped boiler can do. In addition, since the feed water is heated using the heat transfer pipe 21a2, the water level does not decrease compared to the technique of extracting the boiler water in the steam drum 11. Thereby, the boiler can be operated at a stable steam pressure, and the open air due to excessive water level drop can be avoided.
　そして、第２経路２１ｂの経路２１ｂ２と第３経路２１ｃの水の流量が調整され、第２経路２１ｂの経路２１ｂ１及び経路２１ｂ２に水を流通させ第３経路２１ｃに水を流通させなければ、伝熱管２１ａ２で加熱された第１経路２１ａの水は、第２経路２１ｂによって蒸気ドラム１１をバイパスされた未加熱の水と合流され、温度が下げられる。このように、給水加熱用エコノマイザ２に流入する給水温度を下げて所定温度に近づけることができるので、加熱媒体である燃焼排ガスとの温度差を大きく確保することにより、給水加熱用エコノマイザ２における熱回収効率を向上させることができる。 Then, the flow rate of water in the second path 21b and the third path 21c is adjusted, and water is not circulated in the second path 21b and the path 21b1 and the second path 21b2. The water of the first path 21a heated by the heat pipe 21a2 is joined with the unheated water bypassed the steam drum 11 by the second path 21b, and the temperature is lowered. As described above, since the temperature of the feed water flowing into the feed water heating economizer 2 can be lowered to approach the predetermined temperature, the heat in the feed water heating economizer 2 can be reduced by securing a large temperature difference with the combustion exhaust gas as the heating medium. Recovery efficiency can be improved.
　一方、第２経路２１ｂの経路２１ｂ２と第３経路２１ｃの水の流量が調整され、第２経路２１ｂの経路２１ｂ２に水を流通させず、経路２１ｂ１及び第３経路２１ｃに水を流通させれば、第３経路２１ｃから蒸気ドラム１１に給水される水量が増加することによって相対的に第１経路２１ａの流量が減るので、伝熱管２１ａ２によって加熱された水は高温となって温度が上げられる。また、第２経路２１ｂの経路２１ｂ２から導かれた水で第１経路２１ａを流通した水の温度が下げられることがない。
　このように、蒸気ドラム１１内の伝熱管２１ａ２によって給水を加熱するだけでなく、給水加熱用エコノマイザ２に流入する給水温度を、低温腐食を防ぐ所定温度以上の所望温度に調整できる。また、デアレータ（脱気器）等の大掛かりな給水加熱装置が不要となり、かつ、配置スペースを余分に使用することがない。 On the other hand, if the flow rate of water in the second route 21b and the third route 21c is adjusted, water will not flow in the second route 21b, and water will flow in the second route 21b1 and the third route 21c. Since the flow rate of the first path 21a is relatively decreased by the increase of the amount of water supplied to the steam drum 11 from the third path 21c, the water heated by the heat transfer pipe 21a2 becomes high temperature and the temperature is raised. In addition, the temperature of the water flowing through the first path 21a is not lowered by the water led from the path 21b2 of the second path 21b.
As described above, not only the feed water is heated by the heat transfer pipe 21a2 in the steam drum 11, but also the temperature of the feed water flowing into the feed water heating economizer 2 can be adjusted to a desired temperature above the predetermined temperature which prevents low temperature corrosion. In addition, a large-scale water supply heating device such as a deaerator (deaerator) is not required, and an extra arrangement space is not used.
　また、蒸気ドラム１１内のボイラ水中１２の伝熱管２１ａ２内で、（伝熱管２１ａ２の外側の）蒸気ドラム１１内の水と伝熱管２１ａ２内の水とを熱交換して加熱する間接式熱交換を採用している。つまり、本実施形態は、ボイラ水を蒸気ドラムから抜き出して給水の水温度の調整に使用する技術とは異なり、ボイラ水の水位の変動を可及的に防止できるようになっている。 In addition, indirect heat exchange is performed in which heat is exchanged between the water in the steam drum 11 (at the outside of the heat transfer tube 21a2) and the water in the heat transfer tube 21a2 in the heat transfer tube 21a2 of the boiler water 12 in the steam drum Is adopted. That is, unlike the technique of extracting boiler water from a steam drum and using it for adjustment of the water temperature of water supply, this embodiment can prevent fluctuation of the water level of boiler water as much as possible.
　また、給水加熱用エコノマイザ２の入口側の給水温度を制御することができ、給水温度が低温腐食を防止する所定温度（例えば、１３５℃）近くまで下げることができるので、給水加熱用エコノマイザ２における加熱媒体である燃焼排ガスとの温度差を大きく確保することにより、給水加熱用エコノマイザ２における熱回収効率を向上させることができる。 Further, the feed water temperature on the inlet side of the feed water heating economizer 2 can be controlled, and the feed water temperature can be lowered to a predetermined temperature (for example, 135 ° C.) for preventing low temperature corrosion. By securing a large temperature difference with the combustion exhaust gas that is the heating medium, the heat recovery efficiency of the feed water heating economizer 2 can be improved.
　以上、本発明の実施形態について説明したが、発明は上述の実施形態に限定されるものではなく、発明の要旨を逸脱しない範囲において種々変形実施が可能である。
　例えば、本実施形態では、例えば１３５℃とされた所定温度を目標値として流量調整部２５を制御することとしていたが、目標温度に対して所定の温度幅を持たせてもよい。例えば、所定温度は、１３５℃から、プラス５℃の１４０℃までの範囲として５℃の許容範囲を持たせ、流量調整部２５における流量制御が頻繁に切り替えられることを防ぐことができる。 As mentioned above, although embodiment of this invention was described, invention is not limited to the above-mentioned embodiment, A various deformation | transformation implementation is possible in the range which does not deviate from the summary of invention.
For example, in the present embodiment, the flow rate adjusting unit 25 is controlled with the predetermined temperature set to, for example, 135 ° C. as a target value, but a predetermined temperature range may be given to the target temperature. For example, the predetermined temperature may have an allowable range of 5 ° C. as a range from 135 ° C. to 140 ° C. of plus 5 ° C., and the flow rate control in the flow rate adjusting unit 25 can be prevented from being switched frequently.
１　舶用排熱回収システム
２　給水加熱用エコノマイザ
１０　補助ボイラ（ボイラ）
１１　蒸気ドラム
２０　ボイラ給水システム
２１　給水系統
２１ａ　第１経路
２１ａ２　伝熱管
２１ｂ　第２経路
２１ｃ　第３経路
２３　加熱器
２４　温度検出部（温度検出手段）
２５　流量調整部（流量調整手段）
２６　制御部（制御手段） 1 Marine exhaust heat recovery system 2 Economizer for feed water heating 10 Auxiliary boiler (boiler)
11 steam drum 20 boiler water supply system 21 water supply system 21a first route 21a2 heat transfer pipe 21b second route 21c third route 23 heater 24 temperature detection unit (temperature detection means)
25 Flow adjustment part (flow adjustment means)
26 Control unit (control means)

Claims (7)

  1. 　ボイラの蒸気ドラム内のボイラ水と熱交換させた水を、火炉からの排ガスと熱交換する給水加熱用エコノマイザに供給する経路である第１経路と、
    　前記ボイラ水と熱交換させる前の前記第１経路から分岐し、前記蒸気ドラムをバイパスして前記給水加熱用エコノマイザの入口側の合流点で前記第１経路と合流する第２経路と、
    　前記第２経路から分岐し、前記蒸気ドラムに給水する第３経路とを備える給水系統と、
    　前記合流点と前記給水加熱用エコノマイザとの間の水温を検出する温度検出手段と、
    　前記第１経路と前記第２経路と前記第３経路とに流れる水の流量を調整する流量調整手段と、
    　前記温度検出手段で検出される前記水温が、前記給水加熱用エコノマイザの低温腐食を防ぐ所定温度以上となるように、前記流量調整手段を調整する制御手段と、
    を具備するボイラ給水システム。     A first path which is a path for supplying water supplied to the feed water heating economizer which exchanges heat with the boiler water in the steam drum of the boiler and exchanges heat with exhaust gas from the furnace;
    A second path branched from the first path before heat exchange with the boiler water, bypassing the steam drum, and joining the first path at a junction on the inlet side of the feed water heating economizer;
    A water supply system comprising: a third route branched from the second route and supplying water to the steam drum;
    Temperature detection means for detecting the water temperature between the junction and the feed water heating economizer;
    Flow rate adjusting means for adjusting the flow rate of water flowing in the first path, the second path and the third path;
    Control means for adjusting the flow rate adjustment means such that the water temperature detected by the temperature detection means is equal to or higher than a predetermined temperature that prevents low temperature corrosion of the feed water heating economizer;
    Boiler water supply system equipped with.
  2. 　前記第１経路は、前記蒸気ドラム内のボイラ水中に設けられる伝熱管に給水し、前記伝熱管内の水と前記蒸気ドラム内の前記ボイラ水とを熱交換する請求項１に記載のボイラ給水システム。 The boiler feed water according to claim 1, wherein the first path supplies water to a heat transfer pipe provided in boiler water in the steam drum, and exchanges heat between water in the heat transfer pipe and the boiler water in the steam drum. system.
  3. 　前記ボイラは、補助ボイラである請求項１または請求項２に記載のボイラ給水システム。 The boiler water supply system according to claim 1, wherein the boiler is an auxiliary boiler.
  4. 　前記温度検出手段により検出された温度が前記所定温度より小さい場合に、
    　前記第２経路を閉状態とし、前記第１経路と前記第３経路とに流れる水の流量を調整する請求項１から請求項３のいずれかに記載のボイラ給水システム。     When the temperature detected by the temperature detection means is lower than the predetermined temperature,
    The boiler water supply system according to any one of claims 1 to 3, wherein the second path is closed, and the flow rate of water flowing to the first path and the third path is adjusted.
  5. 　前記温度検出手段により検出された温度が前記所定温度より所定値以上大きくなった場合に、
    　前記第３経路を閉状態とし、前記第１経路と前記第２経路とに流れる水の流量を調整する請求項１から請求項４のいずれかに記載のボイラ給水システム。     When the temperature detected by the temperature detection means is higher than the predetermined temperature by a predetermined value or more,
    The boiler feed water system according to any one of claims 1 to 4, wherein the third path is closed, and the flow rate of water flowing to the first path and the second path is adjusted.
  6. 　請求項１から請求項５のいずれかに記載のボイラ給水システムを具備するボイラ。 A boiler comprising the boiler water supply system according to any one of claims 1 to 5.
  7. 　ボイラの蒸気ドラム内のボイラ水と熱交換させた水を、火炉からの排ガスと熱交換する給水加熱用エコノマイザに供給する経路である第１経路と、前記ボイラ水と熱交換させる前の前記第１経路から分岐し、前記蒸気ドラムをバイパスして前記給水加熱用エコノマイザの入口側の合流点で前記第１経路と合流する第２経路と、前記第２経路から分岐し、前記蒸気ドラムに給水する第３経路とを備える給水系統を具備するボイラ給水システムの制御方法であって、
    　前記合流点と前記給水加熱用エコノマイザとの間の水温を検出し、前記水温が、前記給水加熱用エコノマイザの低温腐食を防ぐ所定温度以上となるように、前記第１経路と前記第２経路と前記第３経路とに流れる水の流量を調整する制御方法。
    　     A first path which is a path for supplying water, which is heat-exchanged with boiler water in a steam drum of a boiler, to a feedwater heating economizer which exchanges heat with exhaust gas from a furnace, and the first before heat-exchanged with the boiler water Branching from one path, bypassing the steam drum and joining the first path at the junction on the inlet side of the feed water heating economizer, and branching from the second path, and feeding water to the steam drum A control method of a boiler water supply system comprising a water supply system including a third path to be
    The first path and the second path are detected such that the water temperature between the junction and the feedwater heating economizer is detected, and the water temperature is equal to or higher than a predetermined temperature that prevents low temperature corrosion of the feedwater heating economizer. The control method which adjusts the flow rate of the water which flows to the 3rd above-mentioned course.
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