KR20190141072A - Exhaust heat recovery system and ship - Google Patents

Abstract

The present invention relates to an exhaust heat recovery system and a ship. According to the present invention, the exhaust heat recovery system (40) comprises: a funnel which forms a flow path through which exhaust gas flows; a two-stage heat exchanger (43) formed inside the flow path; a three-stage heat exchanger (44) formed on a lower side in the direction of the flow of the exhaust gas than the two-stage heat exchanger (43) in the flow path; a low pressure line (52) which is accessible to the two-stage heat exchanger (43) and the three-stage heat exchanger (44) for a predetermined flow to be normally distributed therethrough; a water supply line (53) which is accessible to the three-stage heat exchanger (44); and a conversion unit (60) which converts an access status of the low pressure line (52) and the water supply line (53) between the first status, where the low pressure line (52) accesses the two-stage heat exchanger (43), with the water supply line (53) accessing the three-stage heat exchanger (44), and a second status, where the low pressure line (52) accesses both the two-stage heat exchanger (43) and the three-stage heat exchanger (44). The present invention aims to provide an exhaust heat recovery system and a ship, which are able to suppress the damage by a back fire or sulfur powder extracted.

Description

Waste heat recovery system, ship {EXHAUST HEAT RECOVERY SYSTEM AND SHIP}

The present invention relates to a heat recovery system and a ship.

For example, Patent Literature 1 discloses an economizer that generates steam by heating water by heat energy of exhaust gas generated from a cement firing plant, a metal refinery, a chemical plant, a waste incinerator boiler, or the like. The configuration provided with is disclosed. In this configuration, water is supplied to the coal mill by a pump (boiler feed pump).

Japanese Patent Publication No. 5456525

By the way, in the flue which becomes the flow path of exhaust gas, for example, it may be ignited by the unburned powder, the soot, etc. of the fuel contained in exhaust gas, and what is called a backfire may arise. Normally, since a coal mill is cooled by the water supplied in order to produce | generate steam, burnout by backfire is suppressed. However, for some reason, if a backfire is generated when the amount of water supplied to the coal mill is small, there is a possibility that it is burned out.

For example, when sulfur content is contained in exhaust gas, when exhaust gas temperature falls, sulfur content will precipitate and sulfuric acid will be produced | generated. This sulfuric acid may corrode the crusher and the flue.

This invention is made | formed in view of the said situation, and an object of this invention is to provide the heat recovery system and ship which can suppress the damage by backfire and precipitation of sulfur content.

MEANS TO SOLVE THE PROBLEM This invention employs the following means, in order to solve the said subject.

According to the first aspect of the present invention, the heat recovery system includes a flow path forming portion for forming a flow path through which exhaust gas flows, a primary heat exchanger formed in the flow path, and the primary heat exchanger in the flow path. The secondary heat exchanger formed on the downstream side in the flow direction of the exhaust gas, the first heat exchanger and the secondary heat exchanger can be connected to the first line through which a predetermined flow rate flows normally, and the secondary heat exchanger. A first state in which the second line becomes connectable, the first line is connected to the primary heat exchanger, and the second line is connected to the secondary heat exchanger, and the first line is connected to the primary line. And a switching unit for switching the connection state of the first line and the second line between the exchanger and the second state connected to the secondary heat exchanger.

In the normal state, the first line is connected to the primary heat exchanger while the second line is in the first state connected to the secondary heat exchanger. In the secondary heat exchanger formed downstream of the flow direction of the exhaust gas rather than the primary heat exchanger, in the case where damage due to precipitation of the backfire or sulfur is likely to occur, the connection state of the first line and the second line at the switching unit. Switches to the second state.

For example, when the flow rate of the water flowing through the secondary heat exchanger in the first state decreases, water is sent to the secondary heat exchanger from the first line through which the predetermined flow rate normally flows by switching to the second state. As a result, burnout by the backfire is less likely to occur in the secondary heat exchanger.

In addition, as the exhaust gas is subjected to sequential heat exchange in the primary heat exchanger and the secondary heat exchanger, the temperature of the exhaust gas decreases from the upstream side to the downstream side. For this reason, in a 1st state, the temperature of the water which flows through the secondary heat exchanger formed downstream of the flow direction of exhaust gas rather than a primary heat exchanger will become lower than the temperature of the water which flows through a primary heat exchanger. In contrast, in the second state, when water of a higher temperature than the first line is sent from the first line to the primary heat exchanger and the secondary heat exchanger, the temperature of the water flowing through the secondary heat exchanger is increased. Then, the fall of the exhaust gas temperature around the secondary heat exchanger can be suppressed, and precipitation of sulfur can be suppressed.

In this way, damage by backfire or precipitation of sulfur can be suppressed.

According to the second aspect of the present invention, the switching unit according to the first aspect may be configured to separate the second line from the secondary heat exchanger in the second state.

With this configuration, in the second state, water is supplied only to the secondary heat exchanger from the first line. This makes it possible to increase the amount of water sent to the secondary heat exchanger.

According to the 3rd aspect of this invention, the said switching part which concerns on a 1st or 2nd aspect may supply the water which passed through the said secondary heat exchanger to the said primary heat exchanger in the said 2nd state.

With this configuration, in the second state, the water whose temperature is raised is supplied to the primary heat exchanger by heat exchange with the exhaust gas in the secondary heat exchanger. Thereby, in a primary heat exchanger, water can be heated efficiently, and the effective use of thermal energy is aimed at.

According to the 4th aspect of this invention, in the said 2nd line which concerns on any one of 1st-3rd aspect, flow volume may change according to the load amount in the load apparatus connected to the said 2nd line.

In such a configuration, when the flow rate of water in the second line is reduced by the load in the load device, it is possible to switch to the second state in the switching unit and supply water from the first line to the secondary heat exchanger. . Thereby, the flow volume supplied to a secondary heat exchanger can be increased. As a result, burnout of the secondary heat exchanger can be suppressed.

According to the fifth aspect of the present invention, the heat recovery system according to the fourth aspect further includes a flow rate detection unit that detects a flow rate of water in the second line, wherein the switching unit is in the first state, You may make it switch to a said 2nd state, when the flow volume of the water in the said 2nd line detected by the said flow volume detection part is less than a predetermined threshold value.

In such a configuration, when the flow rate of water in the second line detected by the flow rate detection unit falls below a predetermined threshold in the first state, the flow rate supplied to the secondary heat exchanger is increased by switching to the second state. Can be. As a result, burnout of a secondary heat exchanger can be suppressed more reliably.

According to the sixth aspect of the present invention, the switching unit according to any one of the first to fifth aspects is configured according to the type of fuel used in the exhaust gas generating unit that generates the exhaust gas. You may selectively switch either one of the said 2nd states.

With this configuration, for example, the first state can be selected when a fuel containing a small amount of sulfur is used, and the second state can be selected when a fuel containing a large amount of sulfur is used. In the case of using a fuel having a high sulfur content, the sulfur content contained in the exhaust gas increases. In such a case, by selecting the second state, hot water flows to the secondary heat exchanger through the first line rather than through the primary heat exchanger. Thereby, the fall of the exhaust gas temperature around the secondary heat exchanger can be suppressed, and precipitation of sulfur content can be suppressed.

According to the seventh aspect of the present invention, the switching section according to the sixth aspect may select the second state when the sulfur content contained in the fuel exceeds a predetermined reference value.

When the sulfur content contained in the fuel exceeds a predetermined reference value, the fall of the exhaust gas temperature around the secondary heat exchanger is surely suppressed by selecting the second state. Thereby, precipitation of sulfur content can be suppressed more reliably.

According to the 8th aspect of this invention, the heat recovery system which concerns on any one of 1st-7th aspect may further be provided with the control part which controls the operation | movement of the said switch part.

By such a configuration, the switching unit can automatically switch between the first state and the second state according to the flow rate of water in the second line, the kind of fuel, and the like. Thereby, damage by backfire and precipitation of sulfur can be suppressed more reliably.

According to the ninth aspect of the present invention, the ship includes a heat recovery system according to any one of the first to eighth aspects.

By configuring in this way, the ship provided with the heat recovery system which can suppress the damage by backfire and precipitation of sulfur can be provided.

According to the tenth aspect of the present invention, a ship according to the ninth aspect includes a generator driven by a driving force generated by burning fuel, an electric motor driven by electric power generated by the generator, and a driving force of the electric motor. A first propulsion force generating unit for generating a propulsion force, a boiler for generating steam by heating water sent through the second line, a steam turbine driven by steam generated in the boiler, and a driving force of the steam turbine When generating propulsion force, you may provide a 2nd propulsion force generation part.

In such a configuration, when the fuel is burned in order to generate the driving force in the generator serving as the driving source of the first driving force generating portion, the exhaust gas is generated. The heat energy of this generated exhaust gas is used to heat water in the primary heat exchanger and the secondary heat exchanger of the heat recovery system. By sending the heated water to the boiler on the second propulsion force generating portion side, steam can be generated efficiently. Thereby, in the ship provided with the 1st propulsion force generation part and the 2nd propulsion force generation part, the damage by backfire and precipitation of sulfur can be suppressed, using heat energy effectively.

According to the heat recovery system and the ship, damage caused by the backfire or the precipitation of the sulfur can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows schematic structure of the stern part of the ship provided with the heat recovery system in one Embodiment of this invention.
2 is a cross-sectional view seen from the direction of the arrow AA in FIG. 1.
3 is a diagram illustrating a configuration of the heat recovery system in the above embodiment.
It is a figure which shows the flow of water at the time of making the switch part of the heat recovery system of the said embodiment into a 1st state.
It is a figure which shows the flow of water at the time of making the switching part of the heat recovery system of the said embodiment into a 2nd state.
6 is a flowchart illustrating a flow of switching control of the switching unit.

EMBODIMENT OF THE INVENTION Hereinafter, the heat recovery system and ship in one Embodiment of this invention are demonstrated based on drawing.

FIG. 1: is a figure which shows schematic structure of the stern part of the ship provided with the heat recovery system in this embodiment. FIG. 2 is a cross-sectional view seen from the arrow direction A-A of FIG. 1.

As shown in FIG. 1, the ship 10 of this embodiment includes a hull 11, a first propulsion mechanism (first propulsion force generating portion) 20, and a second propulsion mechanism (second propulsion force generating portion). 30 (refer FIG. 2) and the heat recovery system 40 are provided. In addition, in description of this embodiment, although the twin skeg line which has two skgs is demonstrated as an example, it is not limited to a twin skg line.

The ship body 11 has the inclined surface 12s in the ship bottom 12 of the stern part 11b. The inclined surface 12s is gradually inclined upward from the bow (not shown) side toward the stern portion 11b side. As shown to FIG. 1, FIG. 2, the pair of right and left skews 13A and 13B are formed in the inclined surface 12s of the ship bottom 12 at intervals in the line width direction. The pair of left and right skates 13A and 13B are formed so as to project from the inclined surface 12s toward the rear, respectively.

The first propulsion mechanism 20 includes an engine (exhaust gas generator) 21, a generator 22, an electric motor 23, a propeller shaft 24, and a propeller 25.

The engine 21 rotates an output shaft (not shown) by burning fuel. The output shaft of the engine 21 is connected to the generator 22. The engine 21 can select and use LNG (Liquefied Natural Gas), fuel oil, etc. as a fuel. In this embodiment, the engine 21 can use HFO (Heavy Fuel Oil) as fuel as fuel. The generator 22 is driven by the rotation of the output shaft of the engine 21 being transmitted to generate electric power.

The electric motor 23 rotates and drives the propeller shaft 24 around the central axis by the electric power generated by the generator 22.

The propeller shaft 24 is formed in the skeg 13A. One end 24a of the propeller shaft 24 is connected to the electric motor 23 in the hull 11, and the other end 24b protrudes from the hull 11 to the rear of the skeg 13A. .

The propeller 25 is integrally fixed to the other end 24b of the propeller shaft 24 and rotates integrally with the propeller shaft 24.

As shown in FIG. 2, the second propulsion mechanism 30 includes a main boiler (boiler) 31, a steam turbine (loading device) 32, a propeller shaft 34, and a propeller 35. Doing.

The main boiler 31 generates steam by heating water.

The steam turbine 32 rotationally drives the propeller shaft 34 around the central axis by the steam produced by the main boiler 31.

The propeller shaft 34 is formed in the skeg 13B. One end 34a of the propeller shaft 34 is connected to the steam turbine 32 in the hull 11, and the other end 34b protrudes from the hull 11 to the rear of the skeg 13B. have.

The propeller 35 is integrally fixed to the other end 34b of the propeller shaft 34 and rotates integrally with the propeller shaft 34.

The first propulsion mechanism 20 and the second propulsion mechanism 30 are driven by the electric motor 23 and the steam turbine 32 so that the propeller shafts 24 and 34 are rotated around the central axis thereof. The propellers 25 and 35 rotate in a predetermined direction to exert the propulsion force of the ship 10.

As shown in FIG. 1, the ship 10 is equipped with the funnel (flow path forming part) 18 in the upper part of the stern part 11b of the ship body 11. As shown in FIG. The funnel 18 is cylindrical and extends in the vertical direction. The funnel 18 forms a flow path 18r of exhaust gas generated by burning fuel in the engine 21.

3 is a diagram illustrating a configuration of the heat recovery system in this embodiment.

As shown in FIG. 3, the heat recovery system 40 includes a coal mill 41, a high pressure line 51, a low pressure line (first line) 52, and a water supply line (second line) 53. ), A switching unit 60, and a control unit 70.

As shown in FIG. 1, the pelletizer 41 is formed in the funnel 18, for example. The coal mill 41 recovers heat of the exhaust gas flowing through the flow path 18r of the funnel 18, and heats water for generating steam.

As shown in FIG. 3, in the present embodiment, the economizer 41 includes three stages of the first stage heat exchanger 42 and the second stage heat exchanger 1 from the flow direction upstream side of the exhaust gas to the downstream side. And a third heat exchanger (secondary heat exchanger) 44.

The 1st heat exchanger 42, the 2nd heat exchanger 43, and the 3rd heat exchanger 44 are respectively the inlet header pipe 45, the outlet header pipe 46, and the branch pipe ( 47). The inlet header pipe 45 and the outlet header pipe 46 are arranged at intervals in the water flow direction. The branch pipe 47 communicates the inlet header pipe 45 and the outlet header pipe 46. The branch pipe 47 is provided in plural numbers side by side. Thereby, the water which flowed into the inlet header pipe 45 flows branched into the some branch pipe 47. Water passing through the plurality of branch pipes 47 flows into the outlet header pipe 46.

The 1st heat exchanger 42, the 2nd heat exchanger 43, and the 3rd heat exchanger 44 are each inlet by the heat energy of the exhaust gas which flows through the flow path 18r of the funnel 18, respectively. Water flowing from the header pipe 45 to the outlet header pipe 46 via the plurality of branch pipes 47 is heated. Here, the flow path 18r of the funnel 18 by performing heat exchange with water in each of the 1st heat exchanger 42, the 2nd heat exchanger 43, and the 3rd heat exchanger 44 is performed. The temperature of the exhaust gas in) decreases gradually. That is, in the first stage heat exchanger 42, the second stage heat exchanger 43, and the third stage heat exchanger 44, the first stage heat exchanger 42 on the most upstream side of the flow direction of the exhaust gas has a high temperature side, The third stage heat exchanger 44 on the downstream side of the flow direction becomes the low temperature side.

The high pressure line 51 is equipped with the high pressure inlet side line 51A and the high pressure outlet side line 51B. The high pressure inlet side line 51A supplies the water separated from the steam in the separator 19 to the inlet header pipe 45 of the first heat exchanger 42 via the pump 19p.

The high-pressure outlet side line 51B is heated by heat exchange with the exhaust gas in the first heat exchanger 42 to supply water, in which steam and water are mixed, from the outlet header tube 46 to the separator 19. The separator 19 separates water and steam heated in the first heat exchanger 42. The steam separated by the separator 19 is supplied as inboard steam. In this way, by supplying the water heated in the first heat exchanger 42 to the separator 19, the amount of energy required to generate steam in the separator 19 is suppressed. In addition, an auxiliary boiler may be used instead of the separator 19.

The low pressure line 52 has a low pressure inlet side line 52A and a low pressure outlet side line 52B.

The low pressure inlet side line 52A supplies the water separated from the steam in the separator 55 to the inlet header tube 45 of the second heat exchanger 43 through the pump 56.

The low pressure outlet side line 52B is supplied by the second heat exchanger 43 to supply the separator 55 with water mixed with steam and water from the outlet header tube 46. The separator 55 separates water and steam heated in the second heat exchanger 43. In this way, the steam separated by the separator 55 is supplied as the steam turbine 32 or the inboard steam. In addition, the water reduced as the steam is generated is replenished by water supply from the outside.

The water supply line 53 includes a water supply inlet side line 53A and a water supply outlet side line 53B.

The feed water inlet side line 53A discharges water from the steam turbine 32 and passes water through a condenser 33 and a heater (not shown) to the inlet header tube of the third heat exchanger 44. To 45). A heater (not shown) heats the water of the water supply inlet side line 53A using, for example, water (vapor) heated in the second heat exchanger 43 as a heat source.

The water supply outlet side line 53B supplies the heated water to the deaerator 36 by heat exchanging with the exhaust gas in the third stage heat exchanger 44. In the degasser 36, oxygen is removed from the water heated in the third stage heat exchanger 44. The water having passed through the degasser 36 is supplied to the main boiler 31 via the pump 38 and the heater 39. The heater 39 uses water (vapor) heated in the first heat exchanger 42 as a heat source, and heats the water in the water supply outlet side line 53B. In this way, by supplying the water heated in the third stage heat exchanger 44 to the main boiler 31, the amount of energy required to generate steam in the main boiler 31 is suppressed.

The switching unit 60 switches the connection state between the low pressure line 52 and the water supply line 53. The switching unit 60 includes a first three-way valve 61, a second three-way valve 62, a third three-way valve 63, a first bypass line 64, and a second bypass line ( 65 and a third bypass line 66.

The first three-way valve 61 is formed in the low pressure inlet side line 52A. The second three-way valve 62 is formed in the water supply inlet side line 53A. The third three-way valve 63 is formed in the water supply outlet side line 53B.

The first bypass line 64 includes the low pressure inlet side line 52A between the first three-way valve 61 and the inlet header tube 45 of the second heat exchanger 43, and the water supply inlet side line 53A. ) Is connected to the second three-way valve 62.

The second bypass line 65 includes a water supply outlet side line 53B between the third three-way valve 63 and the outlet header tube 46 of the third heat exchanger 44, and the low pressure inlet side line 52A. Is connected to the first three-way valve 61.

The third bypass line 66 includes a water feed inlet side line 53A positioned closer to the steam turbine 32 side than the second three way valve 62, and a third three way valve formed in the feed water outlet side line 53B. 63) is connected.

The switching unit 60 switches the connection between the low pressure line 52 and the water supply line 53 by switching the first three-way valve 61, the second three-way valve 62, and the third three-way valve 63. Switch to the first state and the second state.

It is a figure which shows the flow of water at the time of making the switch part of the heat recovery system of the said embodiment into a 1st state. FIG. 5 is a diagram illustrating the flow of water when the switch is in the second state. FIG.

As shown in FIG. 4, in the first state, the first three-way valve 61, the second three-way valve 62, and the third three-way valve 63 include the low pressure inlet side line 52A and the water supply inlet side line ( 53A) and the water supply outlet side line 53B communicate with each other so that water may be passed through. That is, the first three-way valve 61, the second three-way valve 62, and the third three-way valve 63 connect the first bypass line 64 and the second bypass line 65 to the low pressure inlet side line ( 52A), the water supply inlet side line 53A and the water supply outlet side line 53B are disconnected. Thus, in the low pressure line 52, the predetermined flow rate is normally supplied by the pump 56 from the separator 55 to the second heat exchanger 43 via the low pressure inlet side line 52A. Water (vapor) heated in the second stage heat exchanger 43 is supplied to the separator 55 via the low pressure outlet side line 52B. In addition, in the water supply line 53, the water sent from the water supply inlet side line 53A to the third stage heat exchanger 44 and heated is supplied to the degasser 36 through the water supply outlet side line 53B. .

As shown in FIG. 5, in the second state, the first three-way valve 61, the second three-way valve 62, and the third three-way valve 63 connect the first bypass line 64 to the low pressure inlet side line. 52A is communicated with the water supply inlet side line 53A, and the second bypass line 65 is communicated with the water supply outlet side line 53B and the low pressure inlet side line 52A. Thereby, the water discharged from the separator 55 by the pump 56 at the predetermined | prescribed flow volume is low pressure inlet side line 52A, the 1st three-way valve 61, the 2nd bypass line 65, and the water supply outlet side. Via the line 53B, it is sent to the outlet header tube 46 of the 3rd heat exchanger 44. As shown in FIG. The water heated by heat exchange with the exhaust gas in the third stage heat exchanger 44 is supplied from the inlet header tube 45 of the third stage heat exchanger 44 to the feed water inlet side line 53A and the second three-way valve ( 62), and is sent to the inlet header tube 45 of the second heat exchanger 43 via the first bypass line 64 and the low pressure inlet side line 52A. Water heated by exchanging heat with the exhaust gas in the second heat exchanger 43 passes from the outlet header tube 46 of the second heat exchanger 43 to the separator 55 via the low pressure outlet side line 52B. Supplied. Moreover, in this 2nd state, the water sent from the steam turbine 32 to the water supply inlet side line 53A via the condenser 33 does not pass through the 3rd heat exchanger 44, but passes through a 3rd bypass. It is sent from the line 66 to the water supply outlet side line 53B, and is supplied to the degasser 36 as it is.

The control unit 70 controls the switching operation of the first three-way valve 61, the second three-way valve 62, and the third three-way valve 63, thereby connecting the low pressure line 52 and the water supply line 53. Toggle state. In this embodiment, the control part 70 is based on the flow volume of the water supply outlet side line 53B detected, for example by the flow sensor (flow rate detection part) 71 formed in the water supply outlet side line 53B. Select the first state or the second state. The control part 70 normally carries out the 1st three-way valve 61, the 2nd three-way valve 62, and the 1st so that the connection state of the low-pressure line 52 and the water supply line 53 may be said 1st state. 3 controls the switching operation of the three-way valve 63. When the flow volume of the water supply outlet side line 53B detected by the flow sensor 71 is less than the predetermined threshold, the control part 70 is the 1st three-way valve 61, the 2nd three-way valve 62, and The switching operation of the third three-way valve 63 is controlled so that the connection state between the low pressure line 52 and the water supply line 53 is in the second state. In this second state, water of a predetermined flow rate is supplied to the third heat exchanger 44 by the pump 56. For this reason, in the 3rd stage heat exchanger 44, it can suppress that the flow volume of water runs short.

In addition, although the flow volume of the water supply outlet side line 53B may be detected by the flow sensor 71 as mentioned above, you may acquire based on the data of the water supply amount of the main boiler 31, and the steam generation amount.

The control part 70 selects a 1st state or a 2nd state according to the kind of fuel burned by the engine 21, for example. Specifically, the control part 70 selects a 1st state or a 2nd state according to the quantity (concentration) of the sulfur content contained in the fuel burned by the engine 21. Therefore, the control part 70 acquires the kind of fuel burned by the engine 21 from the fuel information etc. previously registered from the exterior. The control unit 70 normally controls the first three-way valve 61 so that the connection state between the low pressure line 52 and the water supply line 53 is in the first state in the case of using a fuel with little sulfur. The switching operation of the second three-way valve 62 and the third three-way valve 63 is controlled. Moreover, when sulfur, such as an HFO, uses the fuel more than a predetermined reference value, the control part 70 will switch operation of the 1st three-way valve 61, the 2nd three-way valve 62, and the 3rd three-way valve 63. Is controlled so that the connection state of the low pressure line 52 and the water supply line 53 is in the second state. In this second state, water is supplied from the separator 55 to the third heat exchanger 44. The high temperature water heated by the second heat exchanger 43 is supplied from the separator 55. Therefore, the temperature of the 3rd heat exchanger 44 can be suppressed from becoming excessively low, and precipitation of sulfur content by the temperature fall of exhaust gas around the 3rd heat exchanger 44 can be suppressed.

Next, the flow of switching control of the switching unit 60 in the control unit 70 will be described.

6 is a flowchart illustrating a flow of switching control of the switching unit.

As shown in FIG. 6, first, the control unit 70 obtains information indicating the type of fuel to be burned by the engine 21 from fuel information registered in advance from the outside (step S1). Based on the acquired information, it is determined whether the fuel to be used is a material having a predetermined reference value or more of sulfur (step S2). As a result, if sulfur content is not more than the predetermined reference value, the control part 70 makes the connection state of the low pressure line 52 and the water supply line 53 into a 1st state (step S3).

On the other hand, in step S2, when the quantity of sulfur of the fuel used is more than a predetermined reference value, the control part 70 switches the connection state of the low pressure line 52 and the water supply line 53 to a 2nd state. (Step S4). As a result, hot water mixed with the steam generated by heating in the second heat exchanger 43 is supplied from the separator 55 to the third heat exchanger 44. Therefore, even when the sulfur rich fuel is burned, the temperature of the third stage heat exchanger 44 is excessively suppressed, and the temperature of the exhaust gas decreases around the third stage heat exchanger 44. Precipitation of sulfur can be suppressed.

When the connection state of the low pressure line 52 and the water supply line 53 becomes a 1st state by step S2, S3, the control part 70 uses the flow sensor 71 of the water supply outlet side line 53B. The flow rate of water is monitored (step S5).

Here, the flow volume of the water supply outlet side line 53B changes with the load of the main boiler 31 which produces | generates steam using the water supplied from the water supply outlet side line 53B. For example, when the propulsion force generated in the second propulsion mechanism 30 is lowered to lower the navigation speed of the vessel 10, the rotation speed of the propeller shaft 34 is lowered. When the rotation speed of the propeller shaft 34 falls, with this, the load of the steam turbine 32 will fall and the load of the main boiler 31 will also fall.

The control part 70 determines whether the flow volume of the water supply outlet side line 53B detected by the flow sensor 71 was below the predetermined threshold value (step S6). As a result of this determination, if the flow volume of the water supply outlet side line 53B does not fall below a predetermined threshold value (No in step S6), it will return to step S5 and monitoring of a flow volume will repeat every fixed time.

On the other hand, in step S6, when the flow volume of the water supply outlet side line 53B falls below a predetermined threshold (Yes in step S6), the control part 70 controls the low pressure line 52 and the water supply line 53. The connection state is switched to the second state (step S7). Thereby, the water of a predetermined flow rate is supplied to the third heat exchanger 44 by the pump 56. As a result, in the third stage heat exchanger 44, it is suppressed that the flow rate of water is insufficient.

In the heat recovery system 40 of the above-described embodiment, the low pressure line 52 is connected to the second heat exchanger 43, and the water supply line 53 is connected to the third heat exchanger 44. The connection state of the low pressure line 52 and the water supply line 53 is connected between the first state and the second state in which the low pressure line 52 is connected to the second heat exchanger 43 and the third heat exchanger 44. A switching unit 60 for switching is provided.

By such a configuration, in a normal state, the low pressure line 52 is connected to the second heat exchanger 43 and the water supply line 53 is connected to the third heat exchanger 44 in the first state. can do.

On the other hand, in the third stage heat exchanger 44 formed on the downstream side in the flow direction of the exhaust gas than the second stage heat exchanger 43, in the case where damage due to precipitation of bag fire or sulfur is likely to occur, the switching unit ( In 60, the connection state of the low pressure line 52 and the water supply line 53 can be switched to the second state. Therefore, for example, when the flow rate of the water flowing through the third heat exchanger 44 in the first state decreases, the flow is switched to the second state so that the third flow rate is reduced from the low pressure line 52 through which the predetermined flow rate normally flows. Water is sent to the heat exchanger (44). As a result, burnout by the bag fire is hardly generated in the third heat exchanger 44.

In addition, as the exhaust gas is sequentially heat exchanged in the second heat exchanger 43 and the third heat exchanger 44, the temperature of the exhaust gas decreases from the upstream side to the downstream side. Therefore, in the 1st state, the temperature of the water which flows through the 3rd stage heat exchanger 44 formed in the flow direction downstream of the exhaust gas from the 2nd stage heat exchanger 43 flows through the 2nd stage heat exchanger 43. Lower than the water temperature. Thereby, when the density | concentration of the sulfur content contained in exhaust gas is high, sulfur content will precipitate in the 3rd stage heat exchanger 44 of a low temperature side, and sulfuric acid corrosion will arise easily. In this embodiment, in such a situation, the switching part 60 switches the connection state of the low pressure line 52 and the water supply line 53 to a 2nd state. Therefore, the high temperature (for example, about 150 degreeC) water supplied from the separator 55 can be flowed into the 3rd heat exchanger 44 through the water supply line 53. FIG. Therefore, the fall of the exhaust gas temperature around the 3rd stage heat exchanger 44 can be suppressed, and precipitation of sulfur content can be suppressed.

As a result, damage by backfire or precipitation of sulfur can be suppressed.

The switching part 60 of embodiment mentioned above removes the water supply line 53 from the 3rd heat exchanger 44 in a 2nd state. With this configuration, in the second state, water is supplied only to the third heat exchanger 44 from the low pressure line 52. As a result, hotter water flows through the third heat exchanger 44. Therefore, especially when the concentration of sulfur contained in the exhaust gas is high, by switching to the second state, the temperature of the third stage heat exchanger 44 on the low temperature side can be increased more effectively, and the precipitation of sulfur can be suppressed. Can be.

The switching unit 60 further supplies the water that has passed through the third heat exchanger 44 to the second heat exchanger 43 in the second state. With this configuration, in the second state, the water whose temperature is raised by heat exchange with the exhaust gas in the third heat exchanger 44 is supplied to the second heat exchanger 43. Thereby, in the 2nd stage heat exchanger 43, water can be heated efficiently, and effective use of thermal energy is aimed at.

The flow rate of the water supply line 53 of the above-mentioned embodiment changes with the amount of load in the steam turbine 32 connected to the water supply line 53. With this configuration, when the flow rate of the water supply line 53 decreases due to the load in the steam turbine 32, the switching unit 60 switches to the second state and the third heat insulation from the low pressure line 52. Water can be supplied to the exchanger 44. Thereby, the flow volume supplied to the 3rd stage heat exchanger 44 can be increased. As a result, in particular, burnout of the third heat exchanger 44 can be suppressed.

The heat recovery system 40 of the above-described embodiment further includes a flow rate sensor 71 that detects the flow rate of the water supply line 53, and the switching unit 60 has a flow rate sensor when the first state is present. When the flow rate of the water supply line 53 detected at 71 falls below a predetermined threshold, the flow is switched to the second state.

In such a configuration, when the flow rate of the water supply line 53 detected by the flow sensor 71 in the first state falls below the predetermined threshold, the third stage heat exchanger 44 is switched to the second state. Flow rate can be increased. As a result, burnout of the 3rd heat exchanger 44 can be suppressed more reliably.

The switching unit 60 of the above-described embodiment further selectively switches either one of the first state and the second state according to the kind of fuel used in the engine 21 that generates the exhaust gas.

By configuring in this way, for example, when using a fuel with a small content of sulfur, a first state is selected, and when using a fuel with a high content of sulfur, a second state can be selected. In the case of using a fuel having a high sulfur content, the sulfur content contained in the exhaust gas increases. In such a case, by selecting the second state, hotter water flows to the third heat exchanger 44 through the feed water line 53. Thereby, the fall of the exhaust gas temperature around the 3rd stage heat exchanger 44 is suppressed, and precipitation of sulfur content can be suppressed.

The switching unit 60 further selects the second state when the sulfur content contained in the fuel exceeds a predetermined reference value. By configuring in this way, when the sulfur content contained in a fuel exceeds a predetermined reference value, the fall of the exhaust gas temperature around the 3rd stage heat exchanger 44 can be reliably suppressed by selecting a 2nd state, Precipitation of sulfur can be suppressed more reliably.

The heat recovery system 40 of the above-described embodiment further includes a control unit 70 that controls the operation of the switching unit 60. By configuring in this way, the 1st state and the 2nd state can be switched suitably by the switching part 60 according to the flow volume of the water supply line 53, a kind of fuel, etc. Thereby, damage by backfire and precipitation of sulfur can be suppressed more reliably.

The ship 10 of the above-mentioned embodiment uses the heat energy of the exhaust gas produced by burning fuel in the engine 21 used as the drive source of the 1st propulsion mechanism 20, The heat recovery system 40 Water is heated in the second stage heat exchanger (43) and the third stage heat exchanger (44). By sending the heated water to the main boiler 31 on the second propulsion device 30 side, steam can be generated efficiently. Thereby, in the ship provided with the 1st propulsion mechanism 20 and the 2nd propulsion mechanism 30, the damage by backfire and precipitation of sulfur can be suppressed, using heat energy effectively.

(Other modifications)

This invention is not limited to embodiment mentioned above, The thing which added various changes to embodiment mentioned above in the range which does not deviate from the meaning of this invention is included. That is, the specific shape, structure, etc. which were mentioned in embodiment are only an example, and can be changed suitably.

For example, in the above-described embodiment, the second stage heat exchanger 43 and the third stage heat exchanger 44 are directly connected to the low pressure line 52 in the second state. You may connect the heat exchanger 43 and the 3rd stage heat exchanger 44 in parallel.

In the above-mentioned embodiment, in the 2nd state, although the water supply line 53 was made to separate from the 3rd stage heat exchanger 44, it is not limited to this. In the second state, the water supply line 53 may be connected to the third heat exchanger 44 so that the shortage of the flow rate of the water in the water supply line 53 may be supplied from the low pressure line 52.

In the above-described embodiment, the switching from the first state to the second state is automatically performed by the control of the control unit 70, but the switching operation may be performed manually.

In the above-described embodiment, the heat recovery system 40 is provided for the coal mill 41 of the ship 10, but the present invention is not limited to the ship 10, and the present invention is not limited to other plants. It can also be applied to an array recovery system.

10: ship
11: hull
11b: Stern part
12: bottom
12s: slope
13A, 13B: Skag
18: Funnel (Euro formation)
18r: Euro
19: separator
20: first propulsion mechanism (first propulsion force generating unit)
21: engine (exhaust gas generator)
22: generator
23: electric motor
24: propeller shaft
24a: Once
24b: other end
25: propeller
30: second propulsion mechanism (second propulsion force generating unit)
31: main boiler (boiler)
32: steam turbine (loading device)
33: Avenger
34 propeller shaft
34a: Once
34b: other end
35: propeller
36: deaerator
38: pump
39: heater
40: array recovery system
41: cutter
42: first heat exchanger
43: second heat exchanger (primary heat exchanger)
44: third heat exchanger (secondary heat exchanger)
45: entrance header tube
46: outlet header tube
47: branch pipe
51: high pressure line
51A: High Pressure Inlet Line
51B: High Pressure Outlet Line
52: low pressure line (first line)
52A: Low Pressure Inlet Line
52B: Low pressure outlet line
53: water supply line (second line)
53A: Water Inlet Line
53B: water supply outlet line
55 separator
56: pump
60: switching unit
61: first three-way valve
62: second three-way valve
63: third three-way valve
64: first bypass line
65: second bypass line
66: third bypass line
70: control unit
71: flow rate sensor (quantity detection unit)

Claims (10)

A flow path forming unit forming a flow path through which the exhaust gas flows,
A primary heat exchanger formed in the flow path,
A secondary heat exchanger formed downstream of the flow direction of the exhaust gas than the primary heat exchanger in the flow path;
A first line which is connectable to the primary heat exchanger and the secondary heat exchanger, and through which a predetermined flow rate flows normally;
A second line made connectable to said secondary heat exchanger,
A first state in which the first line is connected to the primary heat exchanger, the second line is connected to the secondary heat exchanger, and the first line is connected to the primary heat exchanger and the secondary heat exchanger. And a switching unit for switching the connection state of the first line and the second line between one second state. The method of claim 1,
And the switching unit disconnects the second line from the secondary heat exchanger in the second state. The method according to claim 1 or 2,
And the switching unit supplies the water passing through the secondary heat exchanger to the primary heat exchanger in the second state. The method according to claim 1 or 2,
The heat recovery system of the second line in which the flow rate is changed in accordance with the load in the load device connected to the second line. The method of claim 4, wherein
Further provided with a flow rate detection unit for detecting the flow rate of the water in the second line,
And the switching unit switches to the second state when the flow rate of the water in the second line detected by the flow rate detection unit is lower than a predetermined threshold value in the first state. The method according to claim 1 or 2,
The switching unit selectively converts either one of the first state and the second state in accordance with a type of fuel used in the exhaust gas generation unit that generates the exhaust gas. The method of claim 6,
The conversion unit,
And the second state is selected when the sulfur content contained in the fuel exceeds a predetermined reference value. The method according to claim 1 or 2,
And a control unit for controlling the operation of the switching unit. The ship provided with the heat recovery system of Claim 1 or 2. The method of claim 9,
A generator driven by a driving force generated by burning fuel,
An electric motor driven by electric power generated by the generator,
A first propulsion force generating portion for generating propulsion by the driving force of the electric motor;
A boiler for generating steam by heating water sent through the second line;
A steam turbine driven by steam generated in the boiler;
The ship provided with the 2nd propulsion force generation part when generating the propulsion force by the drive force of the said steam turbine.

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