JP2014085035A - Composite boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite boiler which can balance reduction of a manufacturing cost and space-saving while attempting improvement of a heat recovery efficiency of a waste gas heat.SOLUTION: A composite boiler comprises: multiple main engine smoke tubes 37 draining main engine waste gas into vertical directions; a furnace 47 provided with an oil burning unit 33; multiple oil burning smoke tubes 41 draining oil burning waste gas into the vertical directions; and a drum 30. A plumb partition wall 34 partitioning off the inside of the drum 30 in a low pressure steam generating water room 31 and a high pressure steam generating water room 32, and being substantially parallel for the multiple main engine smoke tubes 37 is provided. The low pressure steam generating water room 31 comprises: a low-pressure steam room 38 which can contain low pressure steam; and a low pressure steam deriving unit 39 which can derive the low pressure steam from the low-pressure steam room 38. The high pressure steam generating water room 32 comprises: a high-pressure steam room 44 which can contain high pressure steam which is higher in pressure than the low pressure steam; and a high pressure steam deriving unit 45 which can derive the high pressure steam from the high-pressure steam room 44.

Description

  The present invention relates to a composite boiler in which a main engine smoke pipe for flowing main engine exhaust gas in the vertical direction and an oil soot smoke pipe for flowing oil tank exhaust gas in the vertical direction are housed in a drum, and in particular, generates steam of different vapor pressures from within a single drum. It relates to possible composite boilers.

  Conventionally, a ship equipped with a diesel engine as a main engine is equipped with a waste heat recovery system aiming at energy saving. This waste heat recovery system generates steam by recovering the calorific value of the exhaust gas of the main engine with an exhaust gas economizer, and the generated steam is used as a power medium for driving the steam turbine of the engine for power generation, as well as in the kitchen and heating of the ship. Used as a heating medium for a heating device.

  In a large waste heat recovery system mounted on a large vessel such as a large container ship or a crude oil transport ship, a water pipe type exhaust gas economizer that can downsize the exhaust gas economizer itself is the mainstream. In this waste heat recovery system, a water / steam circulation circuit is formed between the auxiliary boiler drum or the independent drum and the exhaust gas economizer by water supply / drainage piping, and the auxiliary boiler drum or the independent drum is used as a steam separator. The economizer body is provided with only a heat exchanger that generates steam, thereby omitting the air / water separation function from the exhaust gas economizer body.

In recent years, propulsion performance and diesel engine performance have improved significantly, and even ships with the same transportation capacity tend to have lower engine output than before, and the main engine exhaust gas temperature discharged from the engine tends to decrease. is there. Therefore, especially for small ships such as bulk ships with a main engine output of 10,000 to 20,000 kW or less, sufficient steam capacity required to make the various heaters function in the ship is sufficiently secured by collecting the exhaust gas heat quantity. It has become difficult.
This is because, as will be described below, a steam pressure of 0.6 to 0.7 MPaG is necessary to secure the main propulsion function as a ship, so the exhaust gas economizer equipped in the exhaust system of the main engine Is one of the main factors that is designed to generate steam with a vapor pressure of at least 0.6 to 0.7 MPaG.

Since A heavy oil or light oil, which is a low-sulfur fuel, is expensive, generally low-cost residual oil (C heavy oil) is used as fuel oil in diesel engines.
When this residual oil is used as fuel oil, the residual oil supplied by the fuel oil supply device has a viscosity (10 to 15 cSt) that can be sprayed into the main engine (combustion chamber). When the viscosity of the residual oil is 380 to 700 cSt, it is necessary to heat the temperature of the residual oil to about 135 to 150 ° C. That is, in order to heat the residual oil to the target temperature in accordance with the above requirement, the fuel oil heater generates steam at a heating steam temperature that is about 15 ° C. or more higher than the target temperature of the residual oil (for example, 150 ° C.). Must be generated. The vapor pressure corresponding to the saturated vapor temperature of 165 ° C. is 0.6 MPaG.

On the other hand, heating devices other than those for heating fuel oil, for example, various heating devices such as ship heating and purifiers, can be used at a heating medium temperature lower than that of the main engine fuel oil heater. Their main functions can be secured with a vapor pressure of 3 MPaG.
However, as described above, the exhaust gas economizer is set so as to generate steam having a vapor pressure of 0.6 to 0.7 MPaG. Therefore, after increasing the pressure of the steam to the set pressure, a part of the steam In order to reduce the material cost of the equipment in the system, the pressure is reduced to 0.4 MPaG or less and then supplied to various heating devices. That is, although the high vapor pressure is not required, the exhaust gas economizer is pressurized to 0.6 to 0.7 MPaG as a vapor to be supplied to a heating device other than the fuel oil heater. As a result, the heat recovery efficiency is reduced, resulting in a shortage of exhaust gas heat to cover the required amount of steam in the ship.

Therefore, in order to increase the heat recovery efficiency of the exhaust gas heat quantity, various technologies have been proposed in which a plurality of steam generation mechanisms are installed in series in the exhaust gas passage so that steam at a plurality of pressures can be generated.
The water pipe waste heat recovery system of Patent Document 1 includes a steam turbine that drives a generator, an auxiliary boiler that generates steam, and high-pressure steam generation means that recovers heat from exhaust gas from a diesel main engine to generate high-pressure steam. A low-pressure steam generating means disposed downstream of the high-pressure steam generating means to generate low-pressure steam, a steam supply line for introducing the steam into the steam turbine inlet, and a high-pressure steam separator, and the high-pressure steam to the steam turbine A high-pressure steam line to be introduced into the upper stage and a low-pressure steam line having a low-pressure steam separator to introduce low-pressure steam into the lower stage of the steam turbine, and when the high-pressure steam and the low-pressure steam increase or decrease, supply steam from the steam supply line The amount is controlled to increase or decrease.

  The water pipe steam system of Patent Document 2 is an upstream can body that is installed in an exhaust gas passage and generates high-pressure steam from the exhaust gas, and a middle-flow can body that generates medium-pressure steam from the exhaust gas that flows downstream from the upstream can body. A downstream can body that generates low-pressure steam by exhaust gas flowing downstream from the middle-flow can body, a steam separator provided for each of the can bodies, and the high-pressure steam to boost the low-pressure steam And a booster mechanism.

In small bulk carriers that do not require large boilers, composite boilers (exhaust gas combined auxiliary boilers) are widely used to save space and reduce equipment costs.
This composite boiler accommodates an exhaust gas inlet smoke chamber (main engine exhaust gas introduction section), a plurality of main engine smoke pipes, an oil tank section, a plurality of oil tank smoke pipes, etc. in a drum, and has an auxiliary boiler function in a single device. A natural circulation exhaust gas economizer that combines exhaust gas economizer functions. Therefore, during the voyage, the waste heat of the main engine exhaust gas can be recovered and steam can be generated, and during berthing, fuel oil is burned by the burner of the oil tank section independently of the operation of the main engine. Steam can be generated. Further, when the main engine is decelerating (low load) and the required steam amount on the ship is insufficient, the insufficient steam can be increased by tracking.

JP 2007-1339 A JP 2010-266074 A

Since the water pipe type waste heat recovery system disclosed in Patent Document 1 and Patent Document 2 can generate steam at multiple pressures in this system, a necessary amount of high-pressure steam is eliminated while omitting unnecessary boosting steps. The heat recovery efficiency of the exhaust gas calorie can be improved.
On the other hand, in terms of the structure, the techniques of Patent Documents 1 and 2 require that steam-water separators corresponding to a plurality of steam generating means (steam generating mechanisms) that generate steam at a plurality of pressures are provided corresponding to each steam pressure. In addition, it is necessary to separately install a piping system for communicating the steam generating means corresponding to each steam pressure and the steam separator. Therefore, the production cost increases with the increase in size of the equipment, and there is a risk that the installation area occupied by the equipment may be disadvantageous in terms of space.

In the case of large ships with ample space in the ship, the amount of exhaust gas discharged is large, so it is possible to secure the required amount of steam in the ship by recovering the amount of heat of exhaust gas. It is not impossible to adopt a waste heat recovery system.
However, depending on the specifications, there are many cases where even a large vessel is difficult in terms of space, and in such a vessel, it is not easy to adopt a large waste heat recovery system. In addition, it is difficult for small and medium-sized ships to secure the heat quantity of exhaust gas to cover the required amount of steam in the ship, and since there are many space restrictions, it is difficult to adopt a large-scale waste heat recovery system.

  In a smoke pipe type composite boiler, a plurality of smoke pipes, oil bottles and the like are accommodated in a single drum, and this drum is integrally provided with a steam-water separation function, which is advantageous in terms of space saving. However, when multiple pressure steam is generated with the aim of improving the heat recovery efficiency of the exhaust gas heat quantity, it is necessary to install multiple composite boilers corresponding to the generated multiple steam pressures, and to provide a piping system for each of these multiple composite boilers Therefore, as in the techniques of Patent Documents 1 and 2, there remain problems to be solved in terms of suppressing manufacturing costs and saving space.

An object of the present invention is to provide a composite boiler that can achieve both reduction in production cost and space saving while improving heat recovery efficiency of exhaust gas heat quantity.

  The composite boiler according to claim 1 includes a plurality of main engine smoke pipes that cause main engine exhaust gas to flow vertically from the exhaust gas inlet smoke chamber to the exhaust gas outlet smoke chamber, a furnace provided in an oil tank section, and oil fired exhaust gas to the furnace. A composite boiler comprising a plurality of oil smoke tubes that flow in the vertical direction from the top and a drum that houses at least the plurality of main device smoke tubes, a furnace, and a plurality of oil smoke tubes inside the drum. Partitioning into a low-pressure steam generating water chamber in which a smoke pipe is disposed and a high-pressure steam generating water chamber in which the furnace and a plurality of oil smoke smoke tubes are disposed, and a partition wall substantially parallel to the plurality of main engine smoke tubes The low-pressure steam generating water chamber includes a low-pressure steam chamber that can store low-pressure steam generated by heat exchange between the main engine smoke pipe and water, and a low-pressure steam deriving unit that can derive low-pressure steam from the low-pressure steam chamber. The high-pressure steam A raw water chamber is a high-pressure steam chamber that can store high-pressure steam that is at least a high-pressure steam generated by heat exchange between the oil smoke tube and water and has a pressure higher than that of the low-pressure steam, and a high-pressure steam from the high-pressure steam chamber. It is characterized by having a high-pressure steam lead-out section that can be led out.

The invention of claim 2 is characterized in that, in the invention of claim 1, some of the main engine smoke pipes are arranged inside the high pressure steam generating water chamber.
According to a third aspect of the present invention, in the second aspect of the invention, the high pressure steam generating water chamber includes a high pressure side exhaust gas outlet smoke chamber communicated with the partial main smoke tube among the plurality of main smoke tubes, and the low pressure The steam generating water chamber includes a low-pressure side exhaust gas outlet smoke chamber communicated with the remaining main-unit smoke tubes excluding the partial main-unit smoke tubes among the plurality of main-unit smoke tubes, and is discharged from the high-pressure side exhaust gas outlet smoke chamber An exhaust gas merging section for merging main engine exhaust gas with main engine exhaust gas discharged from the low-pressure side exhaust gas outlet smoke chamber is provided.
The invention of claim 4 is characterized in that, in the invention of claim 3, a flow rate adjusting means capable of adjusting a flow rate of main engine exhaust gas discharged from the high-pressure side exhaust gas outlet smoke chamber is provided in the exhaust gas merging portion.
The invention of claim 5 is the invention according to any one of claims 1 to 4, wherein the high-pressure steam is a heating medium for a main engine fuel oil heater, and the vapor pressure is 0.6 to 0.7 MPaG. The low-pressure steam is a heating medium of a heating device other than the main engine fuel oil heater, and the vapor pressure is set to 0.3 to 0.4 MPaG.

  The invention of claim 6 includes a plurality of main engine smoke pipes for flowing main engine exhaust gas vertically from the exhaust gas inlet smoke chamber to the exhaust gas outlet smoke chamber, a furnace provided in the oil tank section, and oil tank exhaust gas from the furnace. In a composite boiler comprising a plurality of oil soot pipes flowing in the vertical direction and at least a plurality of main engine smoke pipes, a furnace and a drum containing therein a plurality of oil soot smoke pipes, at least low-pressure steam generating water in the drum And a partition wall that is substantially orthogonal to the plurality of main engine smoke pipes, and the low pressure steam generation water chamber is configured to supply low pressure steam generated by heat exchange between the main engine smoke pipes and water. A low-pressure steam chamber that can be accommodated, and a low-pressure steam outlet that can extract low-pressure steam from the low-pressure steam chamber, and the high-pressure steam generation water chamber is generated by heat exchange with the main engine smoke pipe and the oil smoke pipe. High pressure steam A high pressure steam chamber there are capable of accommodating high-pressure steam pressure higher than the low pressure steam in, is characterized by comprising a high pressure steam outlet part can be derived high pressure steam from the high pressure steam chamber.

A seventh aspect of the invention is characterized in that, in the sixth aspect of the invention, the high-pressure steam generating water chamber is disposed closer to the exhaust gas inlet smoke chamber than the low-pressure steam generating water chamber.
The invention according to claim 8 is the invention according to any one of claims 1 to 7, wherein a part of the high-pressure steam derived from the high-pressure steam deriving unit is bypassed to the low-pressure steam derived from the low-pressure steam deriving unit. A steam bypass passage is provided, and decompression means for decompressing high-pressure steam is provided in the steam bypass passage.

According to the first aspect of the present invention, the low pressure steam generating water chamber and the high pressure steam generating water chamber are formed in the single drum by the partition wall substantially parallel to the main engine smoke pipe, and the steam and water can be separated into both steam generating water chambers. Since each of the steam chambers is provided, it is possible to omit the steam / water separator and the piping system respectively corresponding to both the steam generation water chambers while suppressing the overall height of the composite boiler.
Since the low-pressure steam generating water chamber has an exhaust gas economizer function and an air-water separation function, and the high-pressure steam generating water chamber has an auxiliary boiler function and an air-water separation function, it is possible to generate multiple pressure steam with a simple configuration, A necessary amount of high-pressure steam can be generated while omitting an unnecessary pressure increase stroke.
Therefore, it is possible to achieve both reduction in production cost and space saving while improving the heat recovery efficiency of the exhaust gas heat quantity.

According to the invention of claim 2, since a part of the calorific value of the main engine exhaust gas is used for the generation of high-pressure steam, the exhaust gas calorific value can be further effectively used. That is, high-pressure steam can be generated by a part of exhaust gas heat quantity without using fuel oil.
According to the invention of claim 3, the passage of the main engine exhaust gas can be made common, and further space saving can be achieved.
According to the invention of claim 4, the amount of heat of the main engine exhaust gas supplied to the high-pressure steam generating water chamber can be adjusted with a simple configuration.
According to the fifth aspect of the present invention, the required amount of steam can be covered by the amount of steam obtained by collecting the exhaust gas calorific value.

According to the invention of claim 6, the low pressure steam generating water chamber and the high pressure steam generating water chamber are formed in the single drum by the partition wall substantially orthogonal to the main engine smoke pipe, and the steam and water can be separated into both steam generating water chambers. Since each of the steam chambers is provided, it is possible to omit the steam separator and the piping system respectively corresponding to both steam generating water chambers while suppressing the drum diameter of the composite boiler.
Since the low-pressure steam generating water chamber has an exhaust gas economizer function and an air-water separation function, and the high-pressure steam generating water chamber has an auxiliary boiler function and an air-water separation function, it is possible to generate multiple pressure steam with a simple configuration, A necessary amount of high-pressure steam can be generated while omitting an unnecessary pressure increase stroke.
Therefore, it is possible to achieve both reduction in production cost and space saving while improving the heat recovery efficiency of the exhaust gas heat quantity.

According to the seventh aspect of the present invention, the heat quantity of the main engine exhaust gas can be preferentially supplied to the high-pressure steam generation water chamber among the both steam generation water chambers, and high-pressure steam can be efficiently generated.
According to the eighth aspect of the invention, when the low-pressure steam is insufficient, the excess high-pressure steam can be supplied to devices other than the fuel oil heater, and the energy efficiency can be improved.

It is a steam circulation system diagram which shows the whole structure of the waste-heat recovery system which concerns on Example 1 of this invention. 1 is a plan view of a composite boiler according to Embodiment 1. FIG. It is the III-III sectional view taken on the line of FIG. It is the IV-IV sectional view taken on the line of FIG. 3 is a table showing the analysis result of the amount of steam generated by the composite boiler according to Example 1. 6 is a plan view of a composite boiler according to Embodiment 2. FIG. It is the VII-VII sectional view taken on the line of FIG. FIG. 8 is a diagram corresponding to FIG. 7 according to the third embodiment. 10 is a plan view of a composite boiler according to Embodiment 4. FIG. FIG. 10 is a sectional view taken along line XX in FIG. 9.

  Hereinafter, embodiments of the present invention will be described based on examples.

Example 1 is demonstrated based on FIGS. 1-5 As shown in FIG. 1, the ship of a present Example is provided with the main engine 1, the waste heat recovery system S, etc. As shown in FIG. The main engine 1 is, for example, an internal combustion engine of a two-stroke diesel engine with an output of 7,000 kW, and is a main power generation mechanism for obtaining a propulsive force of a ship. In the main engine 1, combustion air supercharged by the supercharger 1a is supplied to the combustion chamber, and simultaneously with the supply air, residual oil (C heavy oil) as fuel is supplied from the main engine fuel oil supply device 2 to the combustion chamber. And sprayed.
The main engine exhaust gas is supplied to the waste heat recovery system S after driving the supercharger 1a.

As shown in FIG. 1, the waste heat recovery system S includes a composite boiler 3 that generates low-pressure steam and high-pressure steam, an excess steam condenser / drain cooler 4, a feed water tank 5, and the feed water tank 5. A water supply pump 6 that can supply water to the composite boiler 3 is provided.
This waste heat recovery system S supplies high-pressure steam as a heating medium to the main engine fuel oil heater 7, and the low-pressure steam as a heating medium is a heating device other than the main engine fuel oil heater 7, specifically, The fuel oil tank heating device 8, the purifier fuel oil heater 9, the purifier lubricating oil heater 10, the heating heater 11, the fresh water heater 12, and the other heating devices 13 are supplied.

First, the steam circulation system of the waste heat recovery system S constituted by a low-pressure steam system pipe and a high-pressure steam system pipe will be briefly described.
As shown in FIG. 1, low-pressure steam flows from the composite boiler 3 through the low-pressure steam passage 21 and is supplied to the heaters 8 to 13, and high-pressure steam flows from the composite boiler 3 through the high-pressure steam passage 22 to heat the main engine fuel oil. To the vessel 7. The heaters 8 to 13 are connected in parallel to the low pressure steam passage 21. The steam that has finished heat exchange as the heating medium in the main engine fuel oil heater 7 and each of the heaters 8 to 13 flows through the drain passage 23 and is drained to the surplus steam condenser / drain cooler 4. In the surplus steam condenser / drain cooler 4, the relieved steam or drain is cooled by seawater to condense or cool.

  The surplus steam condenser / drain cooler 4 is relieved through the relief passages 24 a and 24 b, respectively, from the low pressure steam passage 21 and the high pressure steam passage 22. Surplus steam dump valves 25a and 25b are provided as relief valves in the middle of the relief passages 24a and 24b, respectively. These surplus steam dump valves 25a and 25b have a steam pressure (for example, the low pressure side) slightly higher than the planned normal steam pressure (for example, the low pressure side 0.3 to 0.4 MPaG, the high pressure side 0.6 to 0.7 MPaG). Relief pressures are set so that excess steam flows downstream when the pressure is 0.4 to 0.5 MPaG and the high pressure side is 0.7 to 0.8 MPaG.

The return passage 26 a communicates the excess steam condenser / drain cooler 4 with the water supply tank 5 and returns the condensed water to the water supply tank 5. The return passage 26 b connects the water supply tank 5 to the water supply pump 6 and supplies water stored in the water supply tank 5 to the water supply pump 6.
The water discharged from the water supply pump 6 at the set pressure flows through the water supply passage 27 and is branched into a low-pressure side water supply passage 28 and a high-pressure side water supply passage 29 in the middle of the water supply passage 27. In these low pressure side water supply passage 28 and high pressure side water supply passage 29, water supply control valves 28a, 29a are respectively installed.

Next, the composite boiler 3 will be described.
As shown in FIGS. 1 to 4, the vertical smoke tube type composite boiler 3 is capable of generating steam having a set pressure and a cylindrical drum 30 arranged so that an axial center (center line) extends in the vertical direction. The interior of the low-pressure steam generating water chamber 31, the high-pressure steam generating water chamber 32 capable of generating steam at a higher pressure than the steam generated in the low-pressure steam generating water chamber 31, the oil bottle portion 33, and the drum 30 is partitioned. A vertical partition wall 34 and the like are integrally provided.
The composite boiler 3 of the present embodiment heat-exchanges exhaust gas and water to produce low pressure, for example, low pressure steam of 0.3 to 0.4 MPaG and high pressure, for example, high pressure steam of 0.6 to 0.7 MPaG. Configured to generate. When the vapor pressure is 0.3 MPaG, the saturated vapor temperature is 144 ° C., and when the vapor pressure is 0.6 MPaG, the saturated vapor temperature is 165 ° C.

  The drum 30 is formed as a casing of the composite boiler 3 and is configured to be able to accommodate water for steam generation supplied from the water supply pump 6. The drum 30 is provided with an exhaust gas inlet smoke chamber 35 through which the main engine exhaust gas can be introduced from the main engine 1 via the main engine exhaust gas introduction passage 14 communicated with the main engine 1. A lower end is formed.

  As shown in FIGS. 1, 3, and 4, the low pressure steam generating water chamber 31 includes one side portion of the drum 30, a vertical partition wall 34, an exhaust gas inlet smoke chamber 35, a low pressure side exhaust gas outlet smoke chamber 36, A plurality of low-pressure main machine smoke pipes 37 that flow part of the main engine exhaust gas in a substantially straight shape in the axial direction of the drum 30 from the exhaust gas inlet smoke chamber 35 to the low-pressure side exhaust gas outlet smoke chamber 36, and the plurality of low-pressure main machine smoke pipes 37 A low-pressure steam chamber 38 that can store low-pressure steam generated by heat exchange with water, and a low-pressure steam lead-out section 39 that can lead out the low-pressure steam from the low-pressure steam chamber 38 to the low-pressure steam passage 21. The downstream end of the low-pressure side water supply passage 28 is connected to the lower portion of the peripheral wall of the low-pressure steam generating water chamber 31.

The vertical partition wall 34 is provided substantially parallel to the plurality of low-pressure main engine smoke pipes 37, and blocks the interior of the drum 30 into the low-pressure steam generating water chamber 31 and the high-pressure steam generating water chamber 32.
The main engine exhaust gas outlet passage 15 communicates with the low pressure side exhaust gas outlet smoke chamber 36 to discharge the main engine exhaust gas after heat exchange with water from the low pressure side exhaust gas outlet smoke chamber 36 to the outside.
The low pressure steam chamber 38 has a gas-liquid separation function. The standard water level of the low-pressure steam generating water chamber 31 is set at a position above the plurality of low-pressure main engine smoke pipes 37 in order to completely cool the plurality of low-pressure main engine smoke pipes 37. Therefore, the space formed between the upper wall of the composite boiler 3 and the water surface corresponds to the low pressure steam chamber 38.

  As shown in FIGS. 1, 3, and 4, the high pressure steam generating water chamber 32 includes an oil tank exhaust gas from the other side of the drum 30, an oil tank section 33, an oil tank exhaust gas outlet smoke chamber 40, and a furnace 47. A plurality of oil-smoke pipes 41 flowing the oil-smoke exhaust gas in the direction of the axial center of the drum 30 over the outlet smoke chamber 40, the vertical partition wall 34, the exhaust gas inlet smoke chamber 35, and the high-pressure side exhaust gas outlet smoke A plurality of high-pressure main unit smoke pipes 43 that flow the remainder of the main engine exhaust gas in a substantially straight shape in the axial direction of the drum 30 from the exhaust gas inlet smoke chamber 35 to the high-pressure side exhaust gas outlet smoke chamber 42; The high-pressure steam chamber 44 capable of accommodating high-pressure steam generated by heat exchange between the smoke pipe 41 and the plurality of high-pressure main engine smoke pipes 43 and water, and high-pressure steam derivation capable of deriving high-pressure steam from the high-pressure steam chamber 44 to the high-pressure steam passage 22 Part 45 and the like. The downstream end of the high-pressure side water supply passage 29 is connected to the lower side of the peripheral wall of the high-pressure steam generating water chamber 32. The number of low-pressure main machine smoke pipes 37 and high-pressure main machine smoke pipes 43 is set according to the distribution amount (for example, low-pressure steam side: 80%, high-pressure steam side: 20%) through which the main engine exhaust gas flows.

As shown in FIGS. 1 and 3, the oil tank portion 33 includes a fuel oil burner 46 protruding outward in the radial direction of the drum 30, a furnace 47 installed on the upper wall of the exhaust gas inlet smoke chamber 35 in the drum 30, and the like. It has. Combustion by the fuel oil burner 46 is completed inside the furnace 47, and the soot exhaust gas flows from the furnace 47 through the plurality of soot smoke pipes 41 to the oil soot exhaust gas outlet smoke chamber 40.
The oil soot exhaust gas outlet smoke chamber 40 communicates with the oil soot exhaust gas outlet passage 16 and discharges the oil soot exhaust gas after heat exchange with water from the oil soot exhaust gas exit smoke chamber 40 to the outside.

As shown in FIGS. 1 and 4, an exhaust gas merging passage 48 (exhaust gas merging portion) communicates with the high pressure side exhaust gas outlet smoke chamber 42. The exhaust gas merging passage 48 connects the main engine exhaust gas in the high pressure side exhaust gas outlet smoke chamber 42 to the main engine exhaust gas in the low pressure side exhaust gas outlet smoke chamber 36 by connecting the high pressure side exhaust gas outlet smoke chamber 42 to the main engine exhaust gas outlet passage 15. To the outside.
The high-pressure steam chamber 44 has a gas-liquid separation function. The standard water level of the high pressure steam generating water chamber 32 is set at a position higher than the plurality of oil soot smoke tubes 41 and the plurality of high pressure main engine smoke tubes 43 in order to completely cool the plurality of oil soot smoke tubes 41 and the plurality of high pressure main engine smoke tubes 43. The Therefore, similarly to the low-pressure steam chamber 38, a space formed between the upper wall of the composite boiler 3 and the water surface corresponds to the high-pressure steam chamber 44.

As shown in FIG. 1, the steam bypass passage 49 is configured to connect the high-pressure steam passage 22 to the low-pressure steam passage 21 and to bypass a part of the high-pressure steam led out from the high-pressure steam lead-out portion 45 to the low-pressure steam passage 21. Has been. In the middle of the steam bypass passage 49, a pressure reducing valve 50 (pressure reducing means) capable of arbitrarily adjusting the set pressure is installed.
Thereby, when the low pressure steam supplied to each heater 8-13 runs short, high pressure steam can be decompressed and the amount of low pressure steam can be replenished.

Next, based on FIG. 5, the performance analysis result regarding the generated steam amount of the composite boiler 3 will be described.
The precondition is that the main engine 1 is a diesel engine with an output of 7,000 kW, the feed water temperature is 60 ° C., the set steam pressure in the low pressure steam generating water chamber 31 is 0.3 MPaG, and the set steam pressure in the high pressure steam generating water chamber 32 is 0. The amount of generated steam was calculated when 80% of the main engine exhaust gas flowed to the low-pressure steam generating water chamber 31 and the remaining 20% flowed to the high-pressure steam generating water chamber 32.

As shown in FIG. 5, the composite boiler 3 can simultaneously generate high pressure steam of 106 kg / hr and low pressure steam of 784 kg / hr.
Usually, in a ship having the same conditions as above, the steam consumption of the main engine fuel oil heater is about 90 kg / hr and the steam consumption of other heaters is about 560 kg / hr during the voyage. The required amount of steam in the ship is about 650 kg / hr. Thus, it can be seen that the composite boiler 3 can sufficiently cover the necessary steam amount in the ship required by the main engine fuel oil heater and other heaters by the steam amount obtained by recovering the exhaust gas calorific value.
Here, in a conventional composite boiler that does not have a low-pressure side steam generation part, it is equivalent to flowing 100% exhaust gas to the high-pressure side, and therefore only 531 kg / hr of steam can be generated, so it can be said that it does not cover all of the necessary amount of steam. .

  According to this composite boiler 3, the low-pressure steam generating water chamber 31 and the high-pressure steam generating water chamber 32 are formed in the single drum 30 by the vertical partition wall 34 substantially parallel to the main engine smoke pipes 37, 43, and both steam generating waters are formed. Since the steam chambers 38 and 44 capable of separating water from each other are provided in the chambers 31 and 32, respectively, the steam / water separator and the piping system corresponding to both the steam generating water chambers 31 and 32 are omitted while suppressing the overall height of the composite boiler 3. can do. Since the low-pressure steam generating water chamber 31 has an exhaust gas economizer function and a steam / water separation function, and the high-pressure steam generating water chamber 32 has an auxiliary boiler function and a steam / water separation function, it is possible to generate steam at multiple pressures with a simple configuration. It is possible to generate a necessary amount of high-pressure steam while omitting an unnecessary pressure increasing step. Therefore, it is possible to achieve both reduction in production cost and space saving while improving the heat recovery efficiency of the exhaust gas heat quantity.

A part of the main machine smoke pipes 43 among the plurality of main machine smoke pipes 37, 43 is disposed inside the high-pressure steam generating water chamber 32. Thereby, since a part of heat quantity of main machine exhaust gas is utilized for the production | generation of a high pressure steam, the exhaust gas heat quantity can be used more effectively. That is, high-pressure steam can be generated by a part of exhaust gas heat quantity without using fuel oil.
The high-pressure steam generating water chamber 32 includes a high-pressure side exhaust gas outlet smoke chamber 42 that communicates with some of the main engine smoke tubes 37, 43, and the low-pressure steam generating water chamber 31 includes a plurality of main engine smoke tubes 37. 43, the main engine exhaust gas discharged from the low pressure side exhaust gas outlet smoke chamber 36 is provided with the low pressure side exhaust gas outlet smoke chamber 36 communicated with the remaining main engine smoke pipe 37. Since the exhaust gas merging passage 48 to be joined to the main engine exhaust gas passage is provided, the main engine exhaust gas passage can be shared, and further space saving can be achieved.

A steam bypass passage 49 for bypassing a part of the high-pressure steam derived from the high-pressure steam deriving unit 45 to the low-pressure steam derived from the low-pressure steam deriving unit 39 is provided, and a pressure reducing valve 50 for depressurizing the high-pressure steam in the steam bypass passage 49. Therefore, when low-pressure steam is insufficient, surplus high-pressure steam can be supplied to the heaters 8 to 13 other than those for heating the fuel oil, and energy efficiency can be improved.
The high-pressure steam is a heating medium for the main engine fuel oil heater, the vapor pressure of which is set to 0.6 to 0.7 MPaG, and the low pressure steam is a heater 8 to 13 other than the main engine fuel oil heater 7. Since the vapor pressure is set to 0.3 to 0.4 MPaG, the necessary vapor amount can be covered with the vapor amount obtained by collecting the exhaust gas heat amount.

  Next, a composite boiler 3A according to the second embodiment will be described with reference to FIGS. Only the configuration different from that of the composite boiler 3 of the first embodiment will be described, and the same members as those of the first embodiment are denoted by the same reference numerals and description thereof will be omitted.

As shown in FIG. 7, the composite boiler 3 </ b> A includes a main engine exhaust gas outlet smoke chamber 51 and an oil tank exhaust gas outlet smoke chamber 40 as exhaust gas outlet smoke chambers, and a plurality of high pressure main engine smoke pipes 43 </ b> A include high pressure steam generating water chambers 32. It is arranged at a position close to the inner vertical partition wall 34.
The main engine exhaust gas outlet smoke chamber 51 is disposed so as to straddle the upper portions of the two steam generation water chambers 31 and 32, and accommodates main engine exhaust gas passing through the plurality of low pressure main engine smoke pipes 37 and main engine exhaust gas passing through the plurality of high pressure main engine smoke pipes 43A. It is configured to be possible. The main exhaust gas outlet smoke chamber 51 communicates with the upper ends of a plurality of low-pressure main engine smoke pipes 37 and a plurality of high-pressure main engine smoke pipes 43A. Have joined.

  As shown in FIGS. 6 and 7, the main engine exhaust gas outlet smoke chamber 51 communicates with the main engine exhaust gas outlet passage 15 via a cylindrical exhaust gas junction 52 formed integrally with the upper wall of the main engine exhaust gas outlet smoke chamber 51. Has been. As a result, the exhaust gas outlet smoke chamber of the main engine exhaust gas passing through the low pressure main engine smoke pipe 37 and the main engine exhaust gas passing through the high pressure main engine smoke pipe 43A can be shared, and the main engine exhaust gas passage on the downstream side of the exhaust gas outlet smoke chamber can be shared. Production costs can be reduced and space can be saved.

  Next, a composite boiler 3B according to Example 3 will be described with reference to FIG. Only the configuration different from that of the composite boiler 3 of the first embodiment will be described, and the same members as those of the first embodiment are denoted by the same reference numerals and description thereof will be omitted.

  As shown in FIG. 8, an exhaust gas merging passage 48 </ b> A (exhaust gas merging portion) communicates with the high pressure side exhaust gas outlet smoke chamber 42. The exhaust gas merging passage 48A communicates the high-pressure side exhaust gas outlet smoke chamber 42 with the main engine exhaust gas outlet passage 15 so that the main engine exhaust gas flowing through the high-pressure side exhaust gas outlet smoke chamber 42 becomes the main engine exhaust gas flowing through the low-pressure side exhaust gas outlet smoke chamber 36. Combine and discharge to the outside.

An exhaust gas flow rate adjusting damper 53 (flow rate adjusting means) capable of adjusting the flow rate of the main engine exhaust gas discharged from the high pressure side exhaust gas outlet smoke chamber 42 is provided in the middle of the exhaust gas merging passage 48A. The exhaust gas flow adjustment damper 53 shuts off the exhaust gas merging passage 48A when the low-pressure steam generation request is high or when the high-pressure steam generation request is low, and when the low-pressure steam generation request is low or when the high-pressure steam generation request is high, The merge passage 48A is opened.
Thereby, even if the flow distribution of the main engine exhaust gas flowing through the low-pressure main engine smoke pipe 37 and the high-pressure main engine smoke pipe 43 is structurally preset, the main apparatus supplied to the high-pressure steam generating water chamber 32 with a simple configuration. The amount of heat of the exhaust gas can be adjusted. Note that the exhaust gas flow rate adjustment damper 53 is not limited to two-stage switching between fully closed (blocking) and fully opened (opened), but may be multistage switched or linearly adjusted according to the vapor pressure generation request.

  Next, a composite boiler 3C according to the fourth embodiment will be described with reference to FIGS. Only the configuration different from that of the composite boiler 3 of the first embodiment will be described, and the same members as those of the first embodiment are denoted by the same reference numerals and description thereof will be omitted.

  As shown in FIGS. 9 and 10, the composite boiler 3 </ b> C includes a drum 30 </ b> A that has an axial center extending in the vertical direction, a low-pressure steam generation water chamber 61 that can generate steam at a set pressure, and the low-pressure steam. An intermediate pressure steam generation water chamber 71 capable of generating steam having a pressure higher than that of the steam generated in the generation water chamber 61, and steam having a pressure higher than that of the steam generated in the intermediate pressure steam generation water chamber 71 can be generated. A high-pressure steam generating water chamber 81, an oil bottle portion 33A, and horizontal partition walls 54 and 55 for partitioning the interior of the drum 30A are integrally provided.

  The low pressure steam generating water chamber 61 includes an upper stage portion of the drum 30A, a low pressure side exhaust gas outlet smoke chamber 62, a horizontal partition wall 54 substantially orthogonal to the axis of the drum 30A, and a substantially orthogonal shape to the horizontal partition wall 54. A plurality of low-pressure main engine smoke pipes 63, a low-pressure steam chamber 64 formed between the lower wall of the low-pressure side exhaust gas outlet smoke chamber 62 and the supplied water surface, and a peripheral wall corresponding to the low-pressure steam chamber 64 A low-pressure steam outlet 65 provided in the upper part, a water supply part (not shown) provided in the lower part of the peripheral wall of the low-pressure steam generating water chamber 61, and the like are provided.

The low pressure side exhaust gas outlet smoke chamber 62 and the horizontal partition wall 54 form an upper wall and a lower wall of the low pressure steam generating water chamber 61, respectively. The low pressure side exhaust gas outlet smoke chamber 62 discharges the main engine exhaust gas introduced from the plurality of low pressure main engine smoke pipes 63 through the main engine exhaust gas outlet passage 15 to the outside.
The plurality of low-pressure main engine smoke pipes 63 are configured to flow the main engine exhaust gas introduced from the plurality of medium-pressure main machine smoke pipes 73 through the intermediate pressure side exhaust gas outlet smoke chamber 72 in the vertical direction.
A low pressure steam passage 66 communicates with the low pressure steam outlet 65.

  The intermediate pressure steam generating water chamber 71 includes a middle portion of the drum 30A, an intermediate pressure side exhaust gas outlet smoke chamber 72, a horizontal partition wall 55 substantially orthogonal to the axis of the drum 30A, and substantially orthogonal to the horizontal partition wall 55. A plurality of medium-pressure main machine smoke pipes 73 arranged in a shape, an intermediate-pressure steam chamber 74 formed between the partition wall 54 and the supplied water surface, and an upper portion of the peripheral wall corresponding to the intermediate-pressure steam chamber 74 An intermediate pressure steam lead-out part 75 provided, a water supply part (not shown) provided in the lower part of the peripheral wall of the intermediate pressure steam generation water chamber 71 and the like are provided.

The horizontal partition wall 54 and the horizontal partition wall 55 form an upper wall and a lower wall of the intermediate pressure steam generating water chamber 71, respectively. The medium-pressure side exhaust gas outlet smoke chamber 72 is configured to also serve as the exhaust gas inlet smoke chamber of the low-pressure steam generating water chamber 61, and the main engine exhaust gas introduced from the plurality of medium-pressure main engine smoke pipes 73 is led to the low-pressure main engine smoke pipe 63. The plurality of medium-pressure main machine smoke pipes 73 are configured to flow the main machine exhaust gas introduced from the plurality of high-pressure main machine smoke pipes 83 through the high-pressure side exhaust gas outlet smoke chamber 82 in the vertical direction. An intermediate pressure steam passage 76 communicates with the intermediate pressure steam outlet 75.
A bypass passage 77 for bypassing a part of the intermediate pressure steam to the low pressure steam passage 66 is provided in the middle of the intermediate pressure steam passage 76, and a pressure reducing valve 77 a for reducing the intermediate pressure steam is disposed in the bypass passage 77. ing.

  The high pressure steam generating water chamber 81 includes a lower stage portion of the drum 30 </ b> A, a high pressure side exhaust gas outlet smoke chamber 82, a plurality of high pressure main engine smoke pipes 83 disposed substantially orthogonal to the horizontal partition wall 55, and the horizontal partition wall 55. A high-pressure steam chamber 84 formed between the water surface and the supplied water surface, a high-pressure steam lead-out portion 85 provided in the upper portion of the peripheral wall corresponding to the high-pressure steam chamber 84, an exhaust gas inlet smoke chamber 86, an oil tank A part 33A, an oil soot exhaust gas outlet smoke chamber 40A, a plurality of oil soot smoke pipes 41A, and a water supply part (not shown) provided in the lower part of the peripheral wall of the high-pressure steam generating water chamber 81 are provided.

The horizontal partition wall 55 and the exhaust gas inlet smoke chamber 86 form an upper wall and a lower wall of the high-pressure steam generating water chamber 81, respectively. The high-pressure side exhaust gas outlet smoke chamber 82 is configured to also serve as the exhaust gas inlet smoke chamber of the intermediate-pressure steam generating water chamber 71, and the main engine exhaust gas introduced from the plurality of high-pressure main engine smoke pipes 83 is led to the intermediate pressure main engine smoke pipe 73. . The plurality of high-pressure main engine smoke pipes 83 are configured to flow the main engine exhaust gas introduced from the main engine exhaust gas introduction passage 14 through the exhaust gas inlet smoke chamber 86 in the vertical direction. A high pressure steam passage 86 communicates with the high pressure steam outlet 85.
A bypass passage 87 for bypassing a part of the high-pressure steam to the intermediate-pressure steam passage 76 is provided in the middle of the high-pressure steam passage 86, and a pressure reducing valve 87 a for reducing the high-pressure steam is provided in the bypass passage 87. .

As shown in FIG. 10, the oil tank portion 33A includes a fuel oil burner 46 protruding radially outward from the drum 30A, a furnace 47 mounted on the upper wall of the exhaust gas inlet smoke chamber 86 in the drum 30A, and the like. ing. Combustion by the fuel oil burner 46 is completed inside the furnace 47, and the soot exhaust gas flows from the furnace 47 through the plurality of soot smoke pipes 41A to the oil soot exhaust gas outlet smoke chamber 40A.
The oil soot exhaust gas outlet smoke chamber 40A communicates with the oil soot exhaust gas outlet passage 16A, and the oil soot exhaust gas after heat exchange with water is discharged from the oil soot exhaust gas exit smoke chamber 40A to the outside.

As described above, the low pressure steam generating water chamber 61, the intermediate pressure steam generating water chamber 71, and the high pressure steam generating water chamber 81 are formed in the single drum by the horizontal partition walls 54, 55 substantially orthogonal to the main engine smoke pipes 63, 73, 83. The steam generating water chambers 61, 71, 81 are provided with the steam chambers 64, 74, 84, respectively, which can be separated into steam, so that the steam generating water chambers 61, 71, 81 are suppressed while suppressing the drum diameter of the composite boiler 3 </ b> C. It is possible to omit the steam separator and the piping system corresponding to each.
Since the low and medium pressure steam generating water chambers 61 and 71 have an exhaust gas economizer function and a steam-water separation function, and the high-pressure steam generation water chamber 81 has an auxiliary boiler function and a steam-water separation function, steam of multiple pressures can be configured with a simple configuration. It is possible to generate a necessary amount of high-pressure steam while omitting an unnecessary pressurizing step. Therefore, it is possible to achieve both reduction in production cost and space saving while improving the heat recovery efficiency of the exhaust gas heat quantity.

  Since the high pressure steam generating water chamber 81 is disposed at a position closer to the exhaust gas inlet smoke chamber 86 than the low and medium pressure steam generating water chambers 61 and 71, the high pressure steam generating water chamber 61 and 71 generates high pressure steam. The amount of heat of the main engine exhaust gas can be preferentially supplied to the water chamber 81, and high-pressure steam can be efficiently generated.

Next, a modification in which the above embodiment is partially changed will be described.
1] In the first to third embodiments, the example in which the vertical partition wall is divided into two in the drum in parallel to the drum axis has been described, but may be divided into three or more. In this case, the inside of the drum may be divided by a plurality of parallel vertical partition walls, and the inside of the drum may be divided radially, for example, in a Y shape from the drum axis.

2] In the fourth embodiment, the example in which the two horizontal partition walls are divided into three in the drum perpendicularly to the drum axis has been described, but may be divided into two by a single horizontal partition wall, Moreover, you may divide | segment into four or more divisions by three or more horizontal partition walls. Further, the example in which the exhaust gas outlet smoke chamber for main engine exhaust gas is provided for each steam generating water chamber has been described. However, the exhaust gas outlet smoke chamber for main engine exhaust gas may be provided at least in the uppermost steam generation water chamber. The exhaust gas outlet smoke chamber for main engine exhaust gas in the generation water chamber may be omitted.

3) In addition, those skilled in the art can implement the present invention by adding various modifications to the embodiments without departing from the spirit of the present invention, and the present invention includes such modifications. is there.

  The present invention relates to a composite boiler in which a main engine smoke pipe for flowing main engine exhaust gas in the vertical direction and an oil soot pipe for flowing oil soot exhaust gas in the vertical direction are accommodated in a drum, and steam of different vapor pressures can be generated from a single drum. Therefore, it is possible to achieve both reduction in production cost and space saving while improving the heat recovery efficiency of the exhaust gas calorific value.

S Waste heat recovery system 1 Main engine 3, 3A, 3B Composite boiler, 3C
30, 30A Drum 31, 61 Low pressure steam generating water chamber 32, 81 High pressure steam generating water chamber 33, 33A Oil tank 34 Vertical partition wall 35, 86 Exhaust gas inlet smoke chamber 36, 62 Low pressure side exhaust gas outlet smoke chamber 37, 63 Low pressure Main machine smoke pipe 38, 64 Low pressure steam chamber 39, 65 Low pressure steam outlet 40, 40A Oil soot exhaust gas outlet smoke chamber 41, 41A Oil soot smoke pipe 42, 82 High pressure side exhaust gas outlet smoke chamber 43, 43A, 83 High pressure main engine smoke pipe 44, 84 High pressure steam chambers 45, 85 High pressure steam outlet 48, 48A Exhaust gas confluence passage 51 Main engine exhaust gas outlet smoke chamber 52 Exhaust gas confluence 53 53 Exhaust gas flow rate adjustment dampers 54, 55 Horizontal partition walls

Claims (8)

A plurality of main engine smoke pipes flowing main engine exhaust gas from the exhaust gas inlet smoke chamber to the exhaust gas outlet smoke chamber in the vertical direction, a furnace provided in the oil tank section, and a plurality of oils flowing the oil fired exhaust gas from the furnace in the vertical direction In a composite boiler comprising a soot tube, and a drum containing at least the plurality of main engine smoke tubes, a furnace, and a plurality of oil soot tubes,
The drum is partitioned into a low pressure steam generating water chamber in which the plurality of main engine smoke pipes are arranged and a high pressure steam generating water chamber in which the furnace and a plurality of oil smoke smoke pipes are arranged, and the plurality of main engine smoke pipes A partition wall substantially parallel to the
The low-pressure steam generating water chamber includes a low-pressure steam chamber capable of storing low-pressure steam generated by heat exchange between the main engine smoke pipe and water, and a low-pressure steam deriving unit capable of deriving low-pressure steam from the low-pressure steam chamber;
The high-pressure steam generating water chamber is a high-pressure steam chamber that can store high-pressure steam that is generated by heat exchange of water with at least the oil smoke tube and has a pressure higher than that of the low-pressure steam. A composite boiler comprising a high-pressure steam deriving unit capable of deriving high-pressure steam.   2. The composite boiler according to claim 1, wherein some of the plurality of main engine smoke pipes are disposed inside the high-pressure steam generating water chamber. The high-pressure steam generating water chamber includes a high-pressure side exhaust gas outlet smoke chamber communicated with the partial main-engine smoke pipe among the plurality of main-engine smoke pipes;
The low-pressure steam generating water chamber comprises a low-pressure side exhaust gas outlet smoke chamber communicated with the remaining main-unit smoke pipes excluding the partial main-unit smoke pipes of the plurality of main-engine smoke pipes;
The composite boiler according to claim 2, further comprising an exhaust gas merging portion that joins main engine exhaust gas discharged from the high-pressure side exhaust gas outlet smoke chamber to main engine exhaust gas discharged from the low-pressure side exhaust gas outlet smoke chamber.   The composite boiler according to claim 3, wherein a flow rate adjusting means capable of adjusting a flow rate of main engine exhaust gas discharged from the high-pressure side exhaust gas outlet smoke chamber is provided at the exhaust gas merging portion.   The high-pressure steam is a heating medium for a main engine fuel oil heater, the vapor pressure of which is set to 0.6 to 0.7 MPaG, and the low-pressure steam is a heating medium for a heating device other than the main engine fuel oil heater. And the vapor pressure is set to 0.3-0.4 MPaG, The composite boiler in any one of Claims 1-4 characterized by the above-mentioned. A plurality of main engine smoke pipes flowing main engine exhaust gas from the exhaust gas inlet smoke chamber to the exhaust gas outlet smoke chamber in the vertical direction, a furnace provided in the oil tank section, and a plurality of oils flowing the oil fired exhaust gas from the furnace in the vertical direction In a composite boiler comprising a soot tube, and a drum containing at least the plurality of main engine smoke tubes, a furnace, and a plurality of oil soot tubes,
Partitioning the inside of the drum into at least a low-pressure steam generating water chamber and a high-pressure steam generating water chamber and providing a partition wall substantially orthogonal to the plurality of main engine smoke pipes;
The low-pressure steam generating water chamber includes a low-pressure steam chamber capable of storing low-pressure steam generated by heat exchange between the main engine smoke pipe and water, and a low-pressure steam deriving unit capable of deriving low-pressure steam from the low-pressure steam chamber;
The high-pressure steam generating water chamber is a high-pressure steam chamber that can store high-pressure steam that is high-pressure steam generated by heat exchange with the main engine smoke pipe and oil smoke pipe, and has a pressure higher than that of the low-pressure steam; A composite boiler comprising a high-pressure steam lead-out portion capable of leading out high-pressure steam from a chamber.   The composite boiler according to claim 6, wherein the high-pressure steam generating water chamber is disposed closer to the exhaust gas inlet smoke chamber than the low-pressure steam generating water chamber. A steam bypass passage for bypassing a part of the high-pressure steam derived from the high-pressure steam deriving section to the low-pressure steam derived from the low-pressure steam deriving section is provided, and a decompression means for depressurizing the high-pressure steam is provided in the steam bypass path. The composite boiler according to any one of claims 1 to 7, characterized in that: