WO2017154716A1 - Engine system and control method - Google Patents

Engine system and control method Download PDF

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Publication number
WO2017154716A1
WO2017154716A1 PCT/JP2017/008224 JP2017008224W WO2017154716A1 WO 2017154716 A1 WO2017154716 A1 WO 2017154716A1 JP 2017008224 W JP2017008224 W JP 2017008224W WO 2017154716 A1 WO2017154716 A1 WO 2017154716A1
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WO
WIPO (PCT)
Prior art keywords
egr gas
flow path
egr
scavenging
gas
Prior art date
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PCT/JP2017/008224
Other languages
French (fr)
Japanese (ja)
Inventor
隆道 細野
中島　隆博
正憲 東田
郁美 大西
Original Assignee
川崎重工業株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by 川崎重工業株式会社 filed Critical 川崎重工業株式会社
Priority to CN201780008899.3A priority Critical patent/CN108495993B/en
Priority to KR1020187028570A priority patent/KR102061733B1/en
Publication of WO2017154716A1 publication Critical patent/WO2017154716A1/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B25/00—Engines characterised by using fresh charge for scavenging cylinders
    • F02B25/02—Engines characterised by using fresh charge for scavenging cylinders using unidirectional scavenging
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B29/00—Engines characterised by provision for charging or scavenging not provided for in groups F02B25/00, F02B27/00 or F02B33/00 - F02B39/00; Details thereof
    • F02B29/02—Other fluid-dynamic features of induction systems for improving quantity of charge
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B29/00—Engines characterised by provision for charging or scavenging not provided for in groups F02B25/00, F02B27/00 or F02B33/00 - F02B39/00; Details thereof
    • F02B29/04—Cooling of air intake supply
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D41/0047—Controlling exhaust gas recirculation [EGR]
    • F02D41/0065—Specific aspects of external EGR control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D43/00—Conjoint electrical control of two or more functions, e.g. ignition, fuel-air mixture, recirculation, supercharging or exhaust-gas treatment
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D45/00—Electrical control not provided for in groups F02D41/00 - F02D43/00
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
    • F02M26/22—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories with coolers in the recirculation passage
    • F02M26/33—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories with coolers in the recirculation passage controlling the temperature of the recirculated gases
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
    • F02M26/35—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories with means for cleaning or treating the recirculated gases, e.g. catalysts, condensate traps, particle filters or heaters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M35/00—Combustion-air cleaners, air intakes, intake silencers, or induction systems specially adapted for, or arranged on, internal-combustion engines
    • F02M35/10—Air intakes; Induction systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D41/0047—Controlling exhaust gas recirculation [EGR]
    • F02D41/0065—Specific aspects of external EGR control
    • F02D2041/0067—Determining the EGR temperature
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the present invention relates to an engine system and a control method.
  • Exhaust gas recirculation (EGR) technology that recirculates exhaust gas to the engine has a large NOx emission reduction effect and is widely applied to low environmental load engines. This EGR is also effective for large marine diesel engines. However, large marine diesel engines that use heavy oil as a fuel contain a lot of SOx in the exhaust gas. Therefore, when exhaust gas is recirculated, the exhaust gas (EGR gas) must be washed with a scrubber. It is general (refer patent document 1).
  • a water mist catcher is provided in the scavenging flow path, and sulfuric acid mist can be collected by the water mist catcher.
  • sulfuric acid mist with a very small particle size cannot be collected by the water mist catcher. Will flow into the engine.
  • EGR gas that is not mixed with fresh air may condense in contact with the scavenging gas downstream from the water mist catcher to generate condensed water.
  • the present invention has been made in view of the above circumstances, and an object of the present invention is to provide an engine system capable of suppressing the generation of condensed water due to condensation of EGR gas.
  • An engine system supplies an engine main body, an exhaust passage for discharging exhaust gas discharged from the engine main body to the outside, and scavenging gas obtained by mixing EGR gas with fresh air.
  • a scrubber for cleaning EGR gas with a cleaning liquid, an EGR gas cooler for cooling the EGR gas provided in the EGR flow path, and a dew point temperature of the EGR gas supplied to the scavenging flow path merge with the EGR gas.
  • the air cooler and the EG so as to maintain a non-condensing state lower than the temperature of fresh air and lower than the temperature of the scavenging gas supplied to the engine body.
  • Gas cooler or includes a control unit for controlling both.
  • the dew point temperature of the EGR gas supplied to the scavenging flow path is lower than the temperature of fresh air that merges with the EGR gas and lower than the temperature of the scavenging gas supplied to the engine body. Therefore, when the EGR gas supplied to the scavenging flow passage comes into contact with fresh air or the scavenging gas, it is possible to prevent the EGR gas from condensing and generating condensed water.
  • the control unit maintains the non-condensing state, and a difference between a temperature of fresh air that merges with the EGR gas and a dew point temperature of the EGR gas supplied to the scavenging passage is a predetermined value.
  • the difference between the temperature of the scavenging gas supplied to the engine main body and the dew point temperature of the EGR gas supplied to the scavenging flow path does not exceed the predetermined second upper limit value so as not to exceed the first upper limit value.
  • the air cooler, the EGR gas cooler, or both may be controlled.
  • the difference between the temperature of the fresh air that merges with the EGR gas and the dew point temperature of the EGR gas supplied to the scavenging flow path does not exceed the predetermined first upper limit value, and is supplied to the engine body.
  • Control is performed such that the difference between the temperature of the scavenging gas and the dew point temperature of the EGR gas supplied to the scavenging flow path does not exceed a predetermined second upper limit value, thereby preventing the EGR gas from being excessively cooled. Unnecessary consumption of energy for cooling the gas can be suppressed, and an excessive increase in the temperature of fresh air can be prevented to suppress a decrease in fuel consumption.
  • control unit controls only the EGR gas cooler when the non-condensing state can be maintained only by controlling the EGR gas cooler, and controls the non-condensing state only by controlling the EGR gas cooler. If it cannot be maintained, both the EGR gas cooler and the air cooler may be controlled.
  • An engine system includes an engine main body, an exhaust passage for discharging exhaust gas discharged from the engine main body to the outside, and scavenging gas obtained by mixing EGR gas with fresh air.
  • the control unit transmits an alarm signal.
  • an operator who knows that the EGR gas may condense due to the alarm can be condensed by condensing the EGR gas by controlling the flow rate of the cooling water using an air cooler, EGR gas cooler, or both, for example, by a manual valve. Water generation can be prevented in advance.
  • control method includes an engine main body, an exhaust passage that discharges exhaust gas discharged from the engine main body to the outside, and a scavenging gas obtained by mixing EGR gas with fresh air.
  • An engine system control method comprising: a scrubber provided in a flow path for cleaning EGR gas with a cleaning liquid; and an EGR gas cooler provided in the EGR flow path for cooling EGR gas, wherein the control method is supplied to the scavenging flow path.
  • the dew point temperature of the EGR gas is lower than the temperature of the fresh air that merges with the EGR gas, and lower than the temperature of the scavenging gas supplied to the engine body. So as to maintain the air cooler, the EGR gas cooler, or to control both.
  • FIG. 1 is an overall configuration diagram of an engine system.
  • FIG. 2 is a block diagram of a control system of the engine system.
  • FIG. 3 is a flowchart of control by the control unit of the engine system.
  • FIG. 1 is an overall configuration diagram of the engine system 100.
  • a thick dashed line indicates the flow of exhaust gas or EGR gas
  • a thick solid line indicates the flow of scavenging gas or fresh air gas.
  • the engine system 100 is a marine engine system, and includes an engine body 10, an exhaust passage 20, a scavenging passage 30, an EGR unit 40, and a control unit 50.
  • an engine body 10 an exhaust passage 20, a scavenging passage 30, an EGR unit 40, and a control unit 50.
  • the engine body 10 of the present embodiment is a so-called two-stroke diesel engine. Scavenged gas is supplied to the engine body 10 from the scavenging flow path 30 via the scavenging pipe 11. Scavenging tube 11 is configured to receive a temporary scavenging gas, the scavenging gas temperature sensor 12 in the scavenging pipe 11 for measuring the temperature T s of the scavenging gas, and measures the pressure P s of the scavenging gas A scavenging gas pressure sensor 13 is provided. Further, the exhaust gas discharged from the engine body 10 is temporarily stored in the exhaust pipe 14 and is discharged from the exhaust pipe 14 to the exhaust passage 20.
  • the exhaust flow path 20 is a flow path for discharging the exhaust gas discharged from the engine body 10 to the outside.
  • a turbine unit 22 of the supercharger 21 is provided on the exhaust flow path 20, and the turbine unit 22 rotates by the energy of the exhaust gas.
  • the turbine part 22 is connected to a compressor part 24 provided on the scavenging flow path 30 via a connecting shaft 23. Therefore, when the turbine part 22 rotates, the compressor part 24 will also rotate in connection with this. As the compressor unit 24 rotates, fresh air taken in from the outside is compressed.
  • the scavenging flow path 30 is a flow path for supplying scavenging gas to the engine body 10.
  • the scavenging flow passage 30, with an air cooler 31 for cooling the fresh air compressed by the supercharger 21 is provided, on the downstream air cooler 31 measures the temperature T a of fresh air at the outlet of the air cooler 31
  • An air temperature sensor 32 is provided. The air cooler 31 and the cooling water flows, by controlling the flow rate and temperature of the cooling water, it is possible to adjust the temperature T a of fresh air at the outlet of the air cooler 31.
  • the fresh air that has passed through the air cooler 31 merges with the EGR gas that has passed through the EGR unit 40 at the junction 33 of the scavenging flow path 30, and the fresh air and the EGR gas are mixed to generate scavenging gas.
  • the confluence 33 of the scavenging flow passage 30, the merging point pressure sensor 34 for measuring the pressure P e of the EGR gas is provided at the joining point 33.
  • a water mist catcher 35 that collects water droplets passing through the scavenging flow path 30 is provided on the downstream side of the junction 33 of the scavenging flow path 30. Note that, as described above, water droplets having an extremely small diameter may not be collected by the water mist catcher 35.
  • the EGR unit 40 is a unit that extracts a part of the exhaust gas from the exhaust passage 20 and supplies the exhaust gas to the scavenging passage 30 as EGR gas.
  • the EGR unit 40 has an EGR passage 41 that connects a portion of the exhaust passage 20 upstream of the position of the turbine portion 22 and a portion of the scavenging passage 30 downstream of the compressor portion 24 and the air cooler 31. ing.
  • a water mist catcher 44 and an EGR blower 55 that increases the pressure of the EGR gas and adjusts the flow rate of the EGR gas supplied to the scavenging passage 30 are provided.
  • an EGR gas temperature sensor 46 and an EGR gas pressure sensor 47 for measuring the temperature T g and the pressure P g of the EGR gas at the outlet of the EGR water mist catcher 44 are provided downstream of the EGR water mist catcher 44, respectively.
  • the scrubber 52 removes SOx and dust from the EGR gas using the cleaning liquid, but it is practically impossible to completely remove SOx contained in the EGR gas. For this reason, the EGR gas supplied to the scavenging flow path 30 contains a small amount of SOx, and sulfuric acid mist is generated when this SOx dissolves in water droplets in the scavenging flow path 30.
  • the control unit 50 controls the entire engine system 100, and includes a CPU, a ROM, a RAM, and the like.
  • FIG. 2 is a block diagram of a control system of engine system 100. As shown in FIG. 2, the control unit 50 is electrically connected to the scavenging gas temperature sensor 12, the scavenging gas pressure sensor 13, the air temperature sensor 32, the confluence pressure sensor 34, the EGR gas temperature sensor 46, and the EGR gas pressure sensor 47. It is connected to the. Based on the measurement signals transmitted from these devices, the control unit 50 performs the scavenging gas temperature T s , the scavenging gas pressure P s , and the fresh air temperature at the outlet of the air cooler 31 (hereinafter “new air temperature”).
  • control unit 50 performs various calculations based on the acquired various measurement values, and controls the engine system 100 as a whole.
  • the control unit 50 is electrically connected to the air cooler 31 and the EGR gas cooler 43, and transmits a control signal to these devices based on the results of various calculations and the like. And adjusting the temperature of the EGR gas.
  • the control unit 50 performs control so that the EGR gas is cooled by coming into contact with fresh air or scavenging gas, and as a result, condensed and condensed water is not generated. More specific control contents will be described later.
  • FIG. 3 is a flowchart showing a flow of control by the control unit 50.
  • the control unit 50 first receives measurement signals from various sensors and acquires various measurement values based on these measurement signals (step S1).
  • the control unit 50 based on various measured values obtained in step S1, the dew point temperature of the EGR gas at the confluence point 33 (hereinafter, simply referred to as "dew point temperature”) is calculated T e.
  • the dew point temperature T e [° C.] can be calculated by the following equation (1). In the following equations, it is assumed that the EGR gas at the outlet of the EGR water mist catcher 44 is saturated water vapor (humidity 100% RH).
  • the water vapor partial pressure P 1 of the EGR gas at the confluence point 33 in the equation (2) is determined by the absolute humidity ⁇ 0 [kg / kg] of the EGR gas at the outlet of the EGR water mist catcher 44 and the pressure of the EGR gas at the confluence point 33. It can be calculated by the following formula (3) using P e [Pa]. Among these, the value acquired in step S1 can be used as the pressure P e of the EGR gas at the junction 33. The pressure P e of the EGR gas at the confluence point 33 may use the value of the pressure P s of the scavenging gas.
  • the absolute humidity ⁇ 0 of the EGR gas at the outlet of the EGR water mist catcher 44 is expressed as follows using the water vapor pressure P 0 [Pa] and the pressure P g [Pa] of the EGR gas at the outlet of the EGR water mist catcher 44: It can be calculated by equation (4). Among them, the pressure P g of the EGR gas at the outlet of the EGR water mist catcher 44 may be a value obtained in step S1.
  • the water vapor pressure P 0 of the EGR gas at the outlet of the EGR water mist catcher 44 is expressed by the following equation (5) (Tetens equation) using the temperature T g [° C.] of the EGR gas at the outlet of the EGR water mist catcher 44. ).
  • Temperature T g of the EGR gas at the outlet of the EGR water mist catcher 44 may be a value obtained in step S1.
  • the dew point temperature T e may be calculated by a method other than the above.
  • the dew point temperature T e as long as it greater such as about 2 ° C than the temperature T g of the EGR gas at the outlet of the EGR water mist catcher 44 is found empirically, EGR gas at the outlet of the EGR water mist catcher 44 value obtained by adding 2 ° C to a temperature T g of the may be used as the dew-point temperature T e.
  • the control unit 50 determines a value obtained by subtracting the dew point temperature T e from the fresh air temperature T a is whether greater than a predetermined first lower limit value (e.g., 2 ° C) (step S3).
  • a predetermined first lower limit value e.g. 2 ° C
  • the fresh air temperature T a is higher than the dew point temperature T e, and determines whether the difference is greater than the first lower limit value. If the value obtained by subtracting the dew point temperature T e from the fresh air temperature T a is greater than the first lower limit (YES in step S3), the process proceeds to step S5.
  • the EGR gas is combined with the fresh air, (because there is room) temperature of the EGR gas even as they fell to fresh air temperature T a, the temperature for a certain degree higher than the dew-point temperature T e of the EGR gas No condensation occurs due to the EGR gas joining with fresh air.
  • the control unit 50 controls the EGR gas cooler 43 to lower the temperature of the EGR gas at the outlet of the EGR gas cooler 43 (step S4). As a result, the dew point temperature T e is reduced, it is possible to avoid condensation due to the EGR gas is combined with the fresh air.
  • step S5 the second lower limit value minus the dew point temperature T e from the temperature T s of the scavenging gas is predetermined (e.g., 2 ° C) determines greater or not than. If the value obtained by subtracting the dew point temperature T e from the temperature T s of the scavenging gas is greater than the second lower limit value (YES in step S5), there is no danger of condensation by the EGR gas is in contact with the scavenging gas. In this case, the process proceeds to step S6.
  • the first lower limit value and the second lower limit value may be the same value or different values. Further, the first lower limit value and the second lower limit value may be zero.
  • the control unit 50 controls the EGR gas cooler 43 to lower the temperature of the EGR gas at the outlet of the EGR gas cooler 43 (step S4).
  • dew point temperature T e is reduced, it is possible to EGR gas to avoid condensation caused by contact with the scavenging gas.
  • step S6 it determines the value obtained by subtracting the dew point temperature T e from the fresh air temperature T a is whether less than a predetermined first upper limit value (e.g., 5 ° C). In other words, it is determined whether or not the dew-point temperature T e is not too low than the fresh air temperature T a. Since the value obtained by subtracting the dew point temperature T e from the fresh air temperature T a is not smaller than the first upper limit value (large) (NO in step S6), and thus dew point temperature T e is less than necessary, the control unit 50 controls the EGR gas cooler 43 to increase the temperature of the EGR gas at the outlet of the EGR gas cooler 43 (step S7). Thereby, the consumption of energy for cooling the EGR gas in the EGR gas cooler 43 can be suppressed.
  • a predetermined first upper limit value e.g., 5 ° C
  • step S6 it is determined whether or not the value obtained by subtracting the dew point temperature T e from the temperature T s of the scavenging gas is smaller than a predetermined second upper limit value (e.g., 5 ° C).
  • a predetermined second upper limit value e.g., 5 ° C
  • control The unit 50 controls the EGR gas cooler 43 to increase the temperature of the EGR gas at the outlet of the EGR gas cooler 43 (step S7).
  • the first upper limit value and the second upper limit value may be the same value or different values. However, the first upper limit value is larger than the first lower limit value, and the second upper limit value is larger than the second lower limit value.
  • step S8 When the value obtained by subtracting from the temperature T s of the dew-point temperature T e of the scavenging gas is smaller than the second upper limit value (YES in step S8), it returns to step S1 to repeat the steps S1 to S8. Similarly, when the temperature of the EGR gas at the outlet of the EGR gas cooler 43 is decreased in step S4, and when the temperature of the EGR gas at the outlet of the EGR gas cooler 43 is increased in step S7, the process returns to step S1. Repeat S1 to S8.
  • control unit 50 can maintain a state (non-condensed state) in which the EGR gas does not have a possibility of condensing even when it comes into contact with fresh air or scavenging gas, and in the EGR gas cooler 43 Unnecessary energy consumption can be suppressed.
  • step S4 of the control unit 50 controls the air cooler 31, by increasing the fresh air temperature (new air temperature) T a at the outlet of the air cooler 31, EGR gas is fresh air or An uncondensed state that does not condense even when contacted with the scavenging gas can be maintained.
  • the control unit 50 controls only the EGR gas cooler 43 and only controls the EGR gas cooler 43 when the non-condensing state can be maintained only by controlling the EGR gas cooler 43 (within the range of the maximum cooling capacity of the EGR gas cooler 43). If the uncondensed state cannot be maintained, both the EGR gas cooler 43 and the air cooler 31 may be controlled. According to this configuration, since it controls the fresh air temperature T a to prevent as much as possible is increased, it is possible to suppress deterioration in fuel consumption of the engine body 10.
  • the EGR gas cooler 43 is disposed downstream of the scrubber 42, but the EGR gas cooler 43 may be disposed upstream of the scrubber 42. Further, the EGR unit 40 may have a plurality of scrubbers 42 or may have a plurality of EGR gas coolers 43. For example, a first-stage scrubber 42 (prescrubber) may be provided upstream of the EGR gas cooler 43, and a second-stage scrubber 42 (main scrubber) may be provided downstream of the EGR gas cooler 43. Even with this configuration, if measuring the temperature T g and the pressure P g of the EGR gas can be controlled similar to the control described above.
  • control part 50 demonstrated the case where the air cooler 31, the EGR gas cooler 43, or both were controlled, this control may be performed by the operator. That is, the control unit 50 may warn an operator when the EGR gas may condense, and the operator may control the air cooler 31, the EGR gas cooler 43, or both.

Abstract

An engine system according to one embodiment of the present invention is provided with: an air cooler for cooling fresh air provided to a scavenging flow channel; a scrubber for cleaning, with a cleaning fluid, EGR gas provided to an EGR flow channel; an EGR gas cooler for cooling the EGR gas provided to the EGR flow channel; and a control unit for controlling the air cooler and/or the EGR gas cooler such that a non-condensed state is maintained in which the dew point temperature of the EGR gas supplied to the scavenging flow channel is lower than the temperature of the fresh air joining with the EGR gas, and lower than the temperature of the scavenging gas supplied to an engine main body.

Description

エンジンシステム及び制御方法Engine system and control method
　本発明はエンジンシステム及び制御方法に関する。 The present invention relates to an engine system and a control method.
　排気ガスをエンジンに再循環させる排気再循環（Exhaust Gas Recirculation；ＥＧＲ）技術は、ＮＯｘ排出低減効果が大きく、低環境負荷エンジンに広く適用されている。このＥＧＲは、舶用の大型ディーゼルエンジンにおいても有効である。ただし、重油を燃料とする舶用の大型ディーゼルエンジンは、排気ガスに多くのＳＯｘが含まれることから、排気ガスを再循環させる際には、その排気ガス（ＥＧＲガス）をスクラバによって洗浄するのが一般的である（特許文献１参照）。 Exhaust gas recirculation (EGR) technology that recirculates exhaust gas to the engine has a large NOx emission reduction effect and is widely applied to low environmental load engines. This EGR is also effective for large marine diesel engines. However, large marine diesel engines that use heavy oil as a fuel contain a lot of SOx in the exhaust gas. Therefore, when exhaust gas is recirculated, the exhaust gas (EGR gas) must be washed with a scrubber. It is general (refer patent document 1).
特開２０１１－１５７９５９号公報JP 2011-157959 A
　ＥＧＲガスの洗浄は洗浄液を用いて行われるため、スクラバを通過したＥＧＲガスは飽和状態となる。そのため、ＥＧＲガスが新気と合流して接触すると温度が低下して凝結し、凝縮水が発生することがある。さらに、スクラバによる洗浄ではＥＧＲガスから完全にＳＯｘを取り除くことは難しく、ＥＧＲガスにはＳＯｘがわずかに含まれる。このＥＧＲガスに含まれるＳＯｘが上記の凝縮水に溶け込むと、掃気流路内に硫酸ミストが発生する。そして、硫酸ミストがエンジンに流入した場合には、エンジン内の腐食が進行しやすくなり、また、シリンダライナの異常摩擦が発生するという問題が生じる。 Since cleaning of the EGR gas is performed using a cleaning solution, the EGR gas that has passed through the scrubber is saturated. For this reason, when the EGR gas joins and comes in contact with fresh air, the temperature decreases and condenses, and condensed water may be generated. Furthermore, it is difficult to completely remove SOx from the EGR gas by scrubber cleaning, and the EGR gas contains a small amount of SOx. When SOx contained in the EGR gas is dissolved in the condensed water, sulfuric acid mist is generated in the scavenging flow path. And when sulfuric acid mist flows into an engine, the corrosion in an engine will advance easily and the problem that abnormal friction of a cylinder liner will generate | occur | produce will arise.
　なお、掃気流路にウォータミストキャッチャを設け、ウォータミストキャッチャによって硫酸ミストを捕集することもできるが、硫酸ミストのうち極微小粒径のものは、ウォータミストキャッチャで捕集することができず、エンジンへ流入してしまう。また、新気と混合されていないＥＧＲガスが、ウォータミストキャッチャよりも下流において掃気ガスに接触して凝結し、凝縮水が発生する場合もある。 A water mist catcher is provided in the scavenging flow path, and sulfuric acid mist can be collected by the water mist catcher. However, sulfuric acid mist with a very small particle size cannot be collected by the water mist catcher. Will flow into the engine. In addition, EGR gas that is not mixed with fresh air may condense in contact with the scavenging gas downstream from the water mist catcher to generate condensed water.
　本発明は、以上のような事情に鑑みてなされたものであり、ＥＧＲガスの凝結による凝縮水の発生を抑制できるエンジンシステムの提供を目的としている。 The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an engine system capable of suppressing the generation of condensed water due to condensation of EGR gas.
　本発明の一態様に係るエンジンシステムは、エンジン本体と、前記エンジン本体から排出された排気ガスを外部に放出する排気流路と、新気にＥＧＲガスを混合した掃気ガスを前記エンジン本体に供給する掃気流路と、前記排気流路から抽出した排気ガスをＥＧＲガスとして前記掃気流路に供給するＥＧＲ流路と、前記掃気流路に設けられ新気を冷却するエアクーラと、前記ＥＧＲ流路に設けられＥＧＲガスを洗浄液で洗浄するスクラバと、前記ＥＧＲ流路に設けられＥＧＲガスを冷却するＥＧＲガスクーラと、前記掃気流路に供給されるＥＧＲガスの露点温度が、当該ＥＧＲガスと合流する新気の温度よりも低く、かつ、前記エンジン本体に供給される掃気ガスの温度よりも低い不凝結状態を維持するように、前記エアクーラ、前記ＥＧＲガスクーラ、又はその両方を制御する制御部と、を備えている。 An engine system according to an aspect of the present invention supplies an engine main body, an exhaust passage for discharging exhaust gas discharged from the engine main body to the outside, and scavenging gas obtained by mixing EGR gas with fresh air. A scavenging flow path, an EGR flow path for supplying exhaust gas extracted from the exhaust flow path as EGR gas to the scavenging flow path, an air cooler provided in the scavenging flow path for cooling fresh air, and the EGR flow path A scrubber for cleaning EGR gas with a cleaning liquid, an EGR gas cooler for cooling the EGR gas provided in the EGR flow path, and a dew point temperature of the EGR gas supplied to the scavenging flow path merge with the EGR gas. The air cooler and the EG so as to maintain a non-condensing state lower than the temperature of fresh air and lower than the temperature of the scavenging gas supplied to the engine body. Gas cooler, or includes a control unit for controlling both.
　この構成によれば、掃気流路に供給されるＥＧＲガスの露点温度が、当該ＥＧＲガスと合流する新気の温度よりも低く、かつ、エンジン本体に供給される掃気ガスの温度よりも低くなるよう制御が行われるため、掃気流路に供給されるＥＧＲガスが新気又は掃気ガスと接触したときに、ＥＧＲガスが凝結して凝縮水が発生するのを抑えることができる。 According to this configuration, the dew point temperature of the EGR gas supplied to the scavenging flow path is lower than the temperature of fresh air that merges with the EGR gas and lower than the temperature of the scavenging gas supplied to the engine body. Therefore, when the EGR gas supplied to the scavenging flow passage comes into contact with fresh air or the scavenging gas, it is possible to prevent the EGR gas from condensing and generating condensed water.
　また、上記のエンジンシステムにおいて、前記制御部は、前記不凝結状態を維持するとともに、ＥＧＲガスと合流する新気の温度と前記掃気流路に供給されるＥＧＲガスの露点温度の差が所定の第１上限値を超えないように、かつ、前記エンジン本体に供給される掃気ガスの温度と前記掃気流路に供給されるＥＧＲガスの露点温度の差が所定の第２上限値を超えないように、前記エアクーラ、前記ＥＧＲガスクーラ、又はその両方を制御するようにしてもよい。 In the engine system, the control unit maintains the non-condensing state, and a difference between a temperature of fresh air that merges with the EGR gas and a dew point temperature of the EGR gas supplied to the scavenging passage is a predetermined value. The difference between the temperature of the scavenging gas supplied to the engine main body and the dew point temperature of the EGR gas supplied to the scavenging flow path does not exceed the predetermined second upper limit value so as not to exceed the first upper limit value. In addition, the air cooler, the EGR gas cooler, or both may be controlled.
　この構成によれば、ＥＧＲガスと合流する新気の温度と掃気流路に供給されるＥＧＲガスの露点温度の差が所定の第１上限値を超えないように、かつ、エンジン本体に供給される掃気ガスの温度と掃気流路に供給されるＥＧＲガスの露点温度の差が所定の第２上限値を超えないように制御が行われるため、ＥＧＲガスを過剰に冷却するのを防いでＥＧＲガスを冷却するためのエネルギの不要な消費を抑えることができ、また、新気の温度の過剰な上昇を防いで燃費の低下を抑えることができる。 According to this configuration, the difference between the temperature of the fresh air that merges with the EGR gas and the dew point temperature of the EGR gas supplied to the scavenging flow path does not exceed the predetermined first upper limit value, and is supplied to the engine body. Control is performed such that the difference between the temperature of the scavenging gas and the dew point temperature of the EGR gas supplied to the scavenging flow path does not exceed a predetermined second upper limit value, thereby preventing the EGR gas from being excessively cooled. Unnecessary consumption of energy for cooling the gas can be suppressed, and an excessive increase in the temperature of fresh air can be prevented to suppress a decrease in fuel consumption.
　また、上記のエンジンシステムにおいて、前記制御部は、前記ＥＧＲガスクーラの制御のみで前記不凝結状態を維持できる場合には前記ＥＧＲガスクーラのみを制御し、前記ＥＧＲガスクーラの制御のみで前記不凝結状態を維持できない場合には前記ＥＧＲガスクーラ及び前記エアクーラの両方を制御するようにしてもよい。 In the engine system, the control unit controls only the EGR gas cooler when the non-condensing state can be maintained only by controlling the EGR gas cooler, and controls the non-condensing state only by controlling the EGR gas cooler. If it cannot be maintained, both the EGR gas cooler and the air cooler may be controlled.
　この構成によれば、ＥＧＲガスクーラの制御のみで不凝結状態を維持できる場合にはＥＧＲガスクーラのみを制御するため、可能な限りエアクーラの制御を避けて、新気の温度上昇を防ぐことによりエンジン本体の燃費の低下を抑えることができる。 According to this configuration, when the non-condensing state can be maintained only by the control of the EGR gas cooler, only the EGR gas cooler is controlled. The reduction in fuel consumption can be suppressed.
　また、本発明の他の態様に係るエンジンシステムは、エンジン本体と、前記エンジン本体から排出された排気ガスを外部に放出する排気流路と、新気にＥＧＲガスを混合した掃気ガスを前記エンジン本体に供給する掃気流路と、前記排気流路から抽出した排気ガスをＥＧＲガスとして前記掃気流路に供給するＥＧＲ流路と、前記掃気流路に設けられ新気を冷却するエアクーラと、前記ＥＧＲ流路に設けられＥＧＲガスを洗浄液で洗浄するスクラバと、前記ＥＧＲ流路に設けられＥＧＲガスを冷却するＥＧＲガスクーラと、ＥＧＲガスと合流する新気の温度と前記掃気流路に供給されるＥＧＲガスの露点温度の差が所定の第１下限値以下となったとき、又は、前記エンジン本体に供給される掃気ガスの温度と前記掃気流路に供給されるＥＧＲガスの露点温度の差が所定の第２下限値以下となったとき、所定の警報信号を発信する制御部と、を備えている。 An engine system according to another aspect of the present invention includes an engine main body, an exhaust passage for discharging exhaust gas discharged from the engine main body to the outside, and scavenging gas obtained by mixing EGR gas with fresh air. A scavenging flow path for supplying to the main body, an EGR flow path for supplying the exhaust gas extracted from the exhaust flow path to the scavenging flow path as EGR gas, an air cooler provided in the scavenging flow path for cooling fresh air, A scrubber provided in the EGR flow path for cleaning the EGR gas with a cleaning liquid, an EGR gas cooler provided in the EGR flow path for cooling the EGR gas, a temperature of fresh air that merges with the EGR gas, and the scavenging flow path are supplied. When the difference between the dew point temperatures of the EGR gas becomes a predetermined first lower limit value or below, or the temperature of the scavenging gas supplied to the engine body and the EGR supplied to the scavenging flow path When the difference of the scan of the dew point temperature is equal to or less than the second lower limit value of a predetermined, and a and a control unit for transmitting a predetermined alarm signal.
　この構成によれば、ＥＧＲガスが新気又は掃気ガスと接触することで凝結するおそれがある場合、制御部が警報信号を発信することになる。これにより、警報によってＥＧＲガスが凝結するおそれがあることを知った作業者は、エアクーラ、ＥＧＲガスクーラ、又はその両方を例えば手動バルブによって冷却水の流量を制御することで、ＥＧＲガスの凝結による凝縮水の発生を事前に防ぐことができる。 According to this configuration, when the EGR gas may be condensed due to contact with fresh air or scavenging gas, the control unit transmits an alarm signal. As a result, an operator who knows that the EGR gas may condense due to the alarm can be condensed by condensing the EGR gas by controlling the flow rate of the cooling water using an air cooler, EGR gas cooler, or both, for example, by a manual valve. Water generation can be prevented in advance.
　さらに、本発明の一態様に係る制御方法は、エンジン本体と、前記エンジン本体から排出された排気ガスを外部に放出する排気流路と、新気にＥＧＲガスを混合した掃気ガスを前記エンジン本体に供給する掃気流路と、前記排気流路から抽出した排気ガスをＥＧＲガスとして前記掃気流路に供給するＥＧＲ流路と、前記掃気流路に設けられ新気を冷却するエアクーラと、前記ＥＧＲ流路に設けられＥＧＲガスを洗浄液で洗浄するスクラバと、前記ＥＧＲ流路に設けられＥＧＲガスを冷却するＥＧＲガスクーラと、を備えたエンジンシステムの制御方法であって、前記掃気流路に供給されるＥＧＲガスの露点温度が、当該ＥＧＲガスと合流する新気の温度よりも低く、かつ、前記エンジン本体に供給される掃気ガスの温度よりも低い不凝結状態を維持するように、前記エアクーラ、前記ＥＧＲガスクーラ、又はその両方を制御する。 Furthermore, the control method according to one aspect of the present invention includes an engine main body, an exhaust passage that discharges exhaust gas discharged from the engine main body to the outside, and a scavenging gas obtained by mixing EGR gas with fresh air. A scavenging passage for supplying to the scavenging passage, an EGR passage for supplying the exhaust gas extracted from the exhaust passage to the scavenging passage as EGR gas, an air cooler provided in the scavenging passage for cooling fresh air, and the EGR An engine system control method comprising: a scrubber provided in a flow path for cleaning EGR gas with a cleaning liquid; and an EGR gas cooler provided in the EGR flow path for cooling EGR gas, wherein the control method is supplied to the scavenging flow path. The dew point temperature of the EGR gas is lower than the temperature of the fresh air that merges with the EGR gas, and lower than the temperature of the scavenging gas supplied to the engine body. So as to maintain the air cooler, the EGR gas cooler, or to control both.
　以上のとおり、上記のエンジンシステムによれば、ＥＧＲガスの凝結による凝縮水の発生を抑制することができる。 As mentioned above, according to said engine system, generation | occurrence | production of the condensed water by condensation of EGR gas can be suppressed.
図１は、エンジンシステムの全体構成図である。FIG. 1 is an overall configuration diagram of an engine system. 図２は、エンジンシステムの制御系のブロック図である。FIG. 2 is a block diagram of a control system of the engine system. 図３は、エンジンシステムの制御部による制御のフローチャートである。FIG. 3 is a flowchart of control by the control unit of the engine system.
　以下、本発明の実施形態について図を参照しながら説明する。以下では、全ての図面を通じて同一又は相当する要素には同じ符号を付して、重複する説明は省略する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. Below, the same code | symbol is attached | subjected to the element which is the same or it corresponds through all the drawings, and the overlapping description is abbreviate | omitted.
　＜エンジンシステムの全体構成＞
　はじめに、実施形態に係るエンジンシステム１００の全体構成について説明する。図１は、エンジンシステム１００の全体構成図である。図１において、太く描いた破線は排気ガス又はＥＧＲガスの流れを示しており、太く描いた実線は掃気ガス又は新気ガスの流れを示している。 <Overall configuration of engine system>
First, the overall configuration of the engine system 100 according to the embodiment will be described. FIG. 1 is an overall configuration diagram of the engine system 100. In FIG. 1, a thick dashed line indicates the flow of exhaust gas or EGR gas, and a thick solid line indicates the flow of scavenging gas or fresh air gas.
　本実施形態に係るエンジンシステム１００は舶用のエンジンシステムであって、エンジン本体１０と、排気流路２０と、掃気流路３０と、ＥＧＲユニット４０と、制御部５０と、を備えている。以下、これらの各構成要素について順に説明する。 The engine system 100 according to the present embodiment is a marine engine system, and includes an engine body 10, an exhaust passage 20, a scavenging passage 30, an EGR unit 40, and a control unit 50. Hereinafter, each of these components will be described in order.
　本実施形態のエンジン本体１０は、いわゆる２ストロークディーゼルエンジンである。エンジン本体１０には、掃気管１１を介して掃気流路３０から掃気ガスが供給される。掃気管１１は一時的に掃気ガスを収容するように構成されており、掃気管１１には掃気ガスの温度Ｔｓを測定する掃気ガス温度センサ１２、及び、掃気ガスの圧力Ｐｓを測定する掃気ガス圧力センサ１３が設けられている。また、エンジン本体１０から排出された排気ガスは、排気管１４に一時的に収容され、排気管１４から排気流路２０へと排出される。 The engine body 10 of the present embodiment is a so-called two-stroke diesel engine. Scavenged gas is supplied to the engine body 10 from the scavenging flow path 30 via the scavenging pipe 11. Scavenging tube 11 is configured to receive a temporary scavenging gas, the scavenging gas temperature sensor 12 in the scavenging pipe 11 for measuring the temperature T s of the scavenging gas, and measures the pressure P s of the scavenging gas A scavenging gas pressure sensor 13 is provided. Further, the exhaust gas discharged from the engine body 10 is temporarily stored in the exhaust pipe 14 and is discharged from the exhaust pipe 14 to the exhaust passage 20.
　排気流路２０は、エンジン本体１０から排出された排気ガスを外部に放出する流路である。排気流路２０上には、過給機２１のタービン部２２が設けられており、排気ガスのエネルギによりタービン部２２は回転する。タービン部２２は連結軸２３を介して掃気流路３０上に設けられたコンプレッサ部２４に連結されている。そのため、タービン部２２が回転すると、これに伴ってコンプレッサ部２４も回転する。コンプレッサ部２４が回転することにより、外部から取り込んだ新気が圧縮される。 The exhaust flow path 20 is a flow path for discharging the exhaust gas discharged from the engine body 10 to the outside. A turbine unit 22 of the supercharger 21 is provided on the exhaust flow path 20, and the turbine unit 22 rotates by the energy of the exhaust gas. The turbine part 22 is connected to a compressor part 24 provided on the scavenging flow path 30 via a connecting shaft 23. Therefore, when the turbine part 22 rotates, the compressor part 24 will also rotate in connection with this. As the compressor unit 24 rotates, fresh air taken in from the outside is compressed.
　掃気流路３０は、エンジン本体１０に掃気ガスを供給する流路である。掃気流路３０には、過給機２１により圧縮された新気を冷却するためのエアクーラ３１が設けられているとともに、エアクーラ３１の下流にはエアクーラ３１の出口における新気の温度Ｔａを測定するエア温度センサ３２が設けられている。エアクーラ３１内には冷却水が流れており、この冷却水の流量及び温度を制御することで、エアクーラ３１の出口における新気の温度Ｔａを調整することができる。 The scavenging flow path 30 is a flow path for supplying scavenging gas to the engine body 10. The scavenging flow passage 30, with an air cooler 31 for cooling the fresh air compressed by the supercharger 21 is provided, on the downstream air cooler 31 measures the temperature T a of fresh air at the outlet of the air cooler 31 An air temperature sensor 32 is provided. The air cooler 31 and the cooling water flows, by controlling the flow rate and temperature of the cooling water, it is possible to adjust the temperature T a of fresh air at the outlet of the air cooler 31.
　エアクーラ３１を通過した新気は、掃気流路３０の合流点３３において、ＥＧＲユニット４０を通過したＥＧＲガスと合流し、新気とＥＧＲガスが混合されて掃気ガスが生成される。また、掃気流路３０の合流点３３には、合流点３３におけるＥＧＲガスの圧力Ｐｅを測定する合流点圧力センサ３４が設けられている。さらに、掃気流路３０の合流点３３よりも下流側には、掃気流路３０を通過する水滴を捕集するウォータミストキャッチャ３５が設けられている。なお、前述のとおり極微小径の水滴は、ウォータミストキャッチャ３５で捕集できない場合もある。 The fresh air that has passed through the air cooler 31 merges with the EGR gas that has passed through the EGR unit 40 at the junction 33 of the scavenging flow path 30, and the fresh air and the EGR gas are mixed to generate scavenging gas. Further, the confluence 33 of the scavenging flow passage 30, the merging point pressure sensor 34 for measuring the pressure P e of the EGR gas is provided at the joining point 33. Further, a water mist catcher 35 that collects water droplets passing through the scavenging flow path 30 is provided on the downstream side of the junction 33 of the scavenging flow path 30. Note that, as described above, water droplets having an extremely small diameter may not be collected by the water mist catcher 35.
　ＥＧＲユニット４０は、排気流路２０から排気ガスの一部を抽出し、その排気ガスをＥＧＲガスとして掃気流路３０に供給するユニットである。ＥＧＲユニット４０は、排気流路２０のタービン部２２の位置よりも上流側の部分と掃気流路３０のコンプレッサ部２４及びエアクーラ３１の位置よりも下流側の部分をつなぐＥＧＲ流路４１を有している。ＥＧＲ流路５１には上流側から順に、洗浄液を用いてＥＧＲガスを洗浄するスクラバ４２、スクラバ４２で洗浄したＥＧＲガスを冷却するＥＧＲガスクーラ４３、ＥＧＲガスクーラ４３で発生した凝縮水を捕集するＥＧＲウォータミストキャッチャ４４、ＥＧＲガスを昇圧するとともに掃気流路３０に供給するＥＧＲガスの流量を調整するＥＧＲブロワ５５が設けられている。 The EGR unit 40 is a unit that extracts a part of the exhaust gas from the exhaust passage 20 and supplies the exhaust gas to the scavenging passage 30 as EGR gas. The EGR unit 40 has an EGR passage 41 that connects a portion of the exhaust passage 20 upstream of the position of the turbine portion 22 and a portion of the scavenging passage 30 downstream of the compressor portion 24 and the air cooler 31. ing. A scrubber 42 for cleaning EGR gas using a cleaning liquid, an EGR gas cooler 43 for cooling EGR gas cleaned by the scrubber 42, and EGR for collecting condensed water generated in the EGR gas cooler 43 in order from the upstream side. A water mist catcher 44 and an EGR blower 55 that increases the pressure of the EGR gas and adjusts the flow rate of the EGR gas supplied to the scavenging passage 30 are provided.
　さらに、ＥＧＲウォータミストキャッチャ４４の下流には、ＥＧＲウォータミストキャッチャ４４の出口におけるＥＧＲガスの温度Ｔｇ及び圧力Ｐｇをそれぞれ測定するＥＧＲガス温度センサ４６及びＥＧＲガス圧力センサ４７が設けられている。また、ＥＧＲガスクーラ４３内には冷却水が流れており、この冷却水の流量及び温度を制御することで、ＥＧＲガスクーラ４３の出口におけるＥＧＲガスの温度を調整することができる。 Further, an EGR gas temperature sensor 46 and an EGR gas pressure sensor 47 for measuring the temperature T g and the pressure P g of the EGR gas at the outlet of the EGR water mist catcher 44 are provided downstream of the EGR water mist catcher 44, respectively. . Further, cooling water flows in the EGR gas cooler 43, and the temperature of the EGR gas at the outlet of the EGR gas cooler 43 can be adjusted by controlling the flow rate and temperature of the cooling water.
　なお、前述のとおり、スクラバ５２は、洗浄液を用いてＥＧＲガスからＳＯｘ及びばいじんを取り除くが、ＥＧＲガスに含まれるＳＯｘを完全に取り除くことは実質的に不可能である。そのため、掃気流路３０に供給されるＥＧＲガスには、わずかにＳＯｘが含まれており、このＳＯｘが掃気流路３０内の水滴に溶け込むと硫酸ミストが発生する。 As described above, the scrubber 52 removes SOx and dust from the EGR gas using the cleaning liquid, but it is practically impossible to completely remove SOx contained in the EGR gas. For this reason, the EGR gas supplied to the scavenging flow path 30 contains a small amount of SOx, and sulfuric acid mist is generated when this SOx dissolves in water droplets in the scavenging flow path 30.
　制御部５０は、エンジンシステム１００全体を制御する部分であって、ＣＰＵ、ＲＯＭ、ＲＡＭ等によって構成されている。図２は、エンジンシステム１００の制御系のブロック図である。図２に示すように、制御部５０は、掃気ガス温度センサ１２、掃気ガス圧力センサ１３、エア温度センサ３２、合流点圧力センサ３４、ＥＧＲガス温度センサ４６、及びＥＧＲガス圧力センサ４７と電気的に接続されている。制御部５０は、これらの機器から送信される測定信号に基づいて、それぞれ掃気ガスの温度Ｔｓ、掃気ガスの圧力Ｐｓ、エアクーラ３１の出口における新気の温度（以下、「新気温度」という）Ｔａ、合流点３３におけるＥＧＲガスの圧力Ｐｅ、ＥＧＲウォータミストキャッチャ４４の出口におけるＥＧＲガスの温度Ｔｇ、及びＥＧＲウォータミストキャッチャ４４の出口におけるＥＧＲガスの圧力Ｐｇの各種測定値を取得することができる。 The control unit 50 controls the entire engine system 100, and includes a CPU, a ROM, a RAM, and the like. FIG. 2 is a block diagram of a control system of engine system 100. As shown in FIG. 2, the control unit 50 is electrically connected to the scavenging gas temperature sensor 12, the scavenging gas pressure sensor 13, the air temperature sensor 32, the confluence pressure sensor 34, the EGR gas temperature sensor 46, and the EGR gas pressure sensor 47. It is connected to the. Based on the measurement signals transmitted from these devices, the control unit 50 performs the scavenging gas temperature T s , the scavenging gas pressure P s , and the fresh air temperature at the outlet of the air cooler 31 (hereinafter “new air temperature”). T a , various measured values of EGR gas pressure P e at the confluence 33, EGR gas temperature T g at the outlet of the EGR water mist catcher 44, and EGR gas pressure P g at the outlet of the EGR water mist catcher 44. Can be obtained.
　さらに、制御部５０は、取得した各種測定値に基づいて種々の演算を行い、エンジンシステム１００全体を制御する。本実施形態では、制御部５０は、エアクーラ３１、及びＥＧＲガスクーラ４３と電気的に接続されており、種々の演算等の結果に基づいて、これらの機器へ制御信号を送信し、新気の温度及びＥＧＲガスの温度を調整する。具体的には、制御部５０は、ＥＧＲガスが新気又は掃気ガスに接触することで冷却され、その結果、凝結して凝縮水が発生することがないように制御を行う。より具体的な制御内容については後述する。 Furthermore, the control unit 50 performs various calculations based on the acquired various measurement values, and controls the engine system 100 as a whole. In the present embodiment, the control unit 50 is electrically connected to the air cooler 31 and the EGR gas cooler 43, and transmits a control signal to these devices based on the results of various calculations and the like. And adjusting the temperature of the EGR gas. Specifically, the control unit 50 performs control so that the EGR gas is cooled by coming into contact with fresh air or scavenging gas, and as a result, condensed and condensed water is not generated. More specific control contents will be described later.
　＜制御内容＞
　次に、制御部５０による制御の内容について説明する。図３は、制御部５０による制御の流れを示したフローチャートである。図３に示すように制御が開始されると、まず制御部５０は各種センサから測定信号を受信し、これらの測定信号に基づいて各種測定値を取得する（ステップＳ１）。 <Control details>
Next, the contents of control by the control unit 50 will be described. FIG. 3 is a flowchart showing a flow of control by the control unit 50. When control is started as shown in FIG. 3, the control unit 50 first receives measurement signals from various sensors and acquires various measurement values based on these measurement signals (step S1).
　続いて、制御部５０は、ステップＳ１で取得した各種測定値に基づいて、合流点３３におけるＥＧＲガスの露点温度（以下、単に「露点温度」という）Ｔｅを算出する。露点温度Ｔe［°Ｃ］は、以下の式（１）で算出することができる。なお、以降の式では、ＥＧＲウォータミストキャッチャ４４の出口におけるＥＧＲガスが飽和水蒸気（湿度１００％ＲＨ）であると仮定している。 Subsequently, the control unit 50, based on various measured values obtained in step S1, the dew point temperature of the EGR gas at the confluence point 33 (hereinafter, simply referred to as "dew point temperature") is calculated T e. The dew point temperature T e [° C.] can be calculated by the following equation (1). In the following equations, it is assumed that the EGR gas at the outlet of the EGR water mist catcher 44 is saturated water vapor (humidity 100% RH).
Figure JPOXMLDOC01-appb-M000001
Figure JPOXMLDOC01-appb-M000001
　上記の式（１）におけるｙは、合流点３３におけるＥＧＲガスの水蒸気分圧Ｐ１［Ｐａ］を用いて以下の式（２）で表される。 In the above formula (1) y, by using the water vapor partial pressure P 1 of the EGR gas at the confluence 33 [Pa] represented by Equation (2) below.
Figure JPOXMLDOC01-appb-M000002
Figure JPOXMLDOC01-appb-M000002
　また、式（２）の合流点３３におけるＥＧＲガスの水蒸気分圧Ｐ１は、ＥＧＲウォータミストキャッチャ４４の出口におけるＥＧＲガスの絶対湿度η０［ｋｇ/ｋｇ］及び合流点３３におけるＥＧＲガスの圧力Ｐｅ［Ｐａ］を用いて、以下の式（３）で算出することができる。このうち、合流点３３におけるＥＧＲガスの圧力Ｐｅは、ステップＳ１で取得した値を用いることができる。なお、合流点３３におけるＥＧＲガスの圧力Ｐｅは、掃気ガスの圧力Ｐｓの値を用いてもよい。 Also, the water vapor partial pressure P 1 of the EGR gas at the confluence point 33 in the equation (2) is determined by the absolute humidity η 0 [kg / kg] of the EGR gas at the outlet of the EGR water mist catcher 44 and the pressure of the EGR gas at the confluence point 33. It can be calculated by the following formula (3) using P e [Pa]. Among these, the value acquired in step S1 can be used as the pressure P e of the EGR gas at the junction 33. The pressure P e of the EGR gas at the confluence point 33 may use the value of the pressure P s of the scavenging gas.
Figure JPOXMLDOC01-appb-M000003
Figure JPOXMLDOC01-appb-M000003
　また、ＥＧＲウォータミストキャッチャ４４の出口におけるＥＧＲガスの絶対湿度η０は、ＥＧＲウォータミストキャッチャ４４の出口におけるＥＧＲガスの水蒸気圧Ｐ０［Ｐａ］及び圧力Ｐｇ［Ｐａ］を用いて、以下の式（４）で算出することができる。このうち、ＥＧＲウォータミストキャッチャ４４の出口におけるＥＧＲガスの圧力Ｐｇは、ステップＳ１で取得した値を用いることができる。 The absolute humidity η 0 of the EGR gas at the outlet of the EGR water mist catcher 44 is expressed as follows using the water vapor pressure P 0 [Pa] and the pressure P g [Pa] of the EGR gas at the outlet of the EGR water mist catcher 44: It can be calculated by equation (4). Among them, the pressure P g of the EGR gas at the outlet of the EGR water mist catcher 44 may be a value obtained in step S1.
Figure JPOXMLDOC01-appb-M000004
Figure JPOXMLDOC01-appb-M000004
　また、ＥＧＲウォータミストキャッチャ４４の出口におけるＥＧＲガスの水蒸気圧Ｐ０は、ＥＧＲウォータミストキャッチャ４４の出口におけるＥＧＲガスの温度Ｔｇ［°Ｃ］を用いて以下の式（５）（Tetensの式）で算出することができる。ＥＧＲウォータミストキャッチャ４４の出口におけるＥＧＲガスの温度Ｔｇは、ステップＳ１で取得した値を用いることができる。 Further, the water vapor pressure P 0 of the EGR gas at the outlet of the EGR water mist catcher 44 is expressed by the following equation (5) (Tetens equation) using the temperature T g [° C.] of the EGR gas at the outlet of the EGR water mist catcher 44. ). Temperature T g of the EGR gas at the outlet of the EGR water mist catcher 44 may be a value obtained in step S1.
Figure JPOXMLDOC01-appb-M000005
Figure JPOXMLDOC01-appb-M000005
　以上のとおり、ステップＳ１で取得した各種測定値と上記の式（１）乃至式（５）を用いれば、露点温度Ｔｅを算出することができる。ただし、露点温度Ｔｅは上記以外の方法で算出してもよい。例えば、露点温度Ｔｅは、ＥＧＲウォータミストキャッチャ４４の出口におけるＥＧＲガスの温度Ｔｇよりも例えば約２°Ｃ高いことが経験上判明していれば、ＥＧＲウォータミストキャッチャ４４の出口におけるＥＧＲガスの温度Ｔｇに２°Ｃを加えた値を露点温度Ｔｅとしてもよい。また、本実施形態では、露点温度Ｔｅの算出にあたり、ＥＧＲウォータミストキャッチャ４４の出口におけるＥＧＲガスの温度Ｔｇ及び圧力Ｐｇを用いているが、これに代えて例えばＥＧＲウォータミストキャッチャ４４の入口におけるＥＧＲガスの温度及び圧力を用いてもよい。 As described above, the obtained various measurement values and the equation in step S1 (1) to be used the formula (5), it is possible to calculate the dew-point temperature T e. However, the dew point temperature T e may be calculated by a method other than the above. For example, the dew point temperature T e, as long as it greater such as about 2 ° C than the temperature T g of the EGR gas at the outlet of the EGR water mist catcher 44 is found empirically, EGR gas at the outlet of the EGR water mist catcher 44 value obtained by adding 2 ° C to a temperature T g of the may be used as the dew-point temperature T e. Further, in the present embodiment, in the calculation of the dew-point temperature T e, but using the temperature T g and the pressure P g of the EGR gas at the outlet of the EGR water mist catcher 44, the place of example of EGR water mist catcher 44 which The temperature and pressure of the EGR gas at the inlet may be used.
　続いて、制御部５０は、新気温度Ｔａから露点温度Ｔｅを引いた値が所定の第１下限値（例えば２°Ｃ）よりも大きいか否かを判定する（ステップＳ３）。つまり、新気温度Ｔａが露点温度Ｔｅよりも高く、かつ、その差が第１下限値よりも大きいか否かを判定する。新気温度Ｔａから露点温度Ｔｅを引いた値が第１下限値よりも大きい場合は（ステップＳ３においてＹＥＳ）、ステップＳ５へ進む。この場合、ＥＧＲガスが新気と合流して、ＥＧＲガスの温度が新気温度Ｔａまで下がったとしても、その温度はＥＧＲガスの露点温度Ｔｅよりもある程度高いため（余裕があるため）、ＥＧＲガスが新気と合流することによる凝結は生じない。 Subsequently, the control unit 50 determines a value obtained by subtracting the dew point temperature T e from the fresh air temperature T a is whether greater than a predetermined first lower limit value (e.g., 2 ° C) (step S3). In other words, the fresh air temperature T a is higher than the dew point temperature T e, and determines whether the difference is greater than the first lower limit value. If the value obtained by subtracting the dew point temperature T e from the fresh air temperature T a is greater than the first lower limit (YES in step S3), the process proceeds to step S5. In this case, the EGR gas is combined with the fresh air, (because there is room) temperature of the EGR gas even as they fell to fresh air temperature T a, the temperature for a certain degree higher than the dew-point temperature T e of the EGR gas No condensation occurs due to the EGR gas joining with fresh air.
　一方、新気温度Ｔａから露点温度Ｔｅを引いた値が第１下限値よりも大きくない場合（ステップＳ３においてＮＯ）、ＥＧＲガスが新気と合流したときにＥＧＲガスが凝結して凝縮水が発生するおそれがある。この場合、制御部５０は、ＥＧＲガスクーラ４３を制御して、ＥＧＲガスクーラ４３の出口におけるＥＧＲガスの温度を低下させる（ステップＳ４）。これにより、露点温度Ｔｅは低下し、ＥＧＲガスが新気と合流することによる凝結を回避することができる。 On the other hand, when the value obtained by subtracting the dew point temperature T e from the fresh air temperature T a is not greater than the first lower limit value (NO in step S3), and then EGR gas condenses when the EGR gas having been mixed with fresh air condenses There is a risk of water generation. In this case, the control unit 50 controls the EGR gas cooler 43 to lower the temperature of the EGR gas at the outlet of the EGR gas cooler 43 (step S4). As a result, the dew point temperature T e is reduced, it is possible to avoid condensation due to the EGR gas is combined with the fresh air.
　ステップＳ５では、掃気ガスの温度Ｔｓから露点温度Ｔｅを引いた値が所定の第２下限値（例えば、２°Ｃ）よりも大きいか否かを判定する。掃気ガスの温度Ｔｓから露点温度Ｔｅを引いた値が第２下限値よりも大きい場合は（ステップＳ５においてＹＥＳ）、ＥＧＲガスが掃気ガスと接触することによって凝結するおそれはない。この場合、ステップＳ６へ進む。なお、第１下限値及び第２下限値は互いに同じ値であってもよく、別の値であってもよい。また、第１下限値及び第２下限値はゼロであってもよい。 In step S5, the second lower limit value minus the dew point temperature T e from the temperature T s of the scavenging gas is predetermined (e.g., 2 ° C) determines greater or not than. If the value obtained by subtracting the dew point temperature T e from the temperature T s of the scavenging gas is greater than the second lower limit value (YES in step S5), there is no danger of condensation by the EGR gas is in contact with the scavenging gas. In this case, the process proceeds to step S6. Note that the first lower limit value and the second lower limit value may be the same value or different values. Further, the first lower limit value and the second lower limit value may be zero.
　一方、掃気ガスの温度Ｔｓから露点温度Ｔｅを引いた値が所定の下限値よりも大きくない場合（ステップＳ５においてＮＯ）、ＥＧＲガスが掃気ガスと接触したときにＥＧＲガスが凝結するおそれがある。この場合、制御部５０は、ＥＧＲガスクーラ４３を制御して、ＥＧＲガスクーラ４３の出口におけるＥＧＲガスの温度を低下させる（ステップＳ４）。これにより、露点温度Ｔｅは低下し、ＥＧＲガスが掃気ガスと接触することによる凝結を回避することができる。 On the other hand, a possibility if the value obtained by subtracting the dew point temperature T e from the temperature T s of the scavenging gas is not greater than the predetermined lower limit value (NO in step S5), and the EGR gas when the EGR gas is in contact with the scavenging gas condenses There is. In this case, the control unit 50 controls the EGR gas cooler 43 to lower the temperature of the EGR gas at the outlet of the EGR gas cooler 43 (step S4). Thus, dew point temperature T e is reduced, it is possible to EGR gas to avoid condensation caused by contact with the scavenging gas.
　ステップＳ６では、新気温度Ｔａから露点温度Ｔｅを引いた値が所定の第１上限値（例えば５°Ｃ）よりも小さいか否かを判定する。つまり、露点温度Ｔｅが新気温度Ｔａよりも低すぎないか否かを判定する。新気温度Ｔａから露点温度Ｔｅを引いた値が第１上限値よりも小さくない（大きい）場合（ステップＳ６においてＮＯ）、必要以上に露点温度Ｔｅが低いことになるため、制御部５０はＥＧＲガスクーラ４３を制御して、ＥＧＲガスクーラ４３の出口におけるＥＧＲガスの温度を上昇させる（ステップＳ７）。これにより、ＥＧＲガスクーラ４３におけるＥＧＲガスを冷却するためのエネルギの消費を抑えることができる。 In step S6, it determines the value obtained by subtracting the dew point temperature T e from the fresh air temperature T a is whether less than a predetermined first upper limit value (e.g., 5 ° C). In other words, it is determined whether or not the dew-point temperature T e is not too low than the fresh air temperature T a. Since the value obtained by subtracting the dew point temperature T e from the fresh air temperature T a is not smaller than the first upper limit value (large) (NO in step S6), and thus dew point temperature T e is less than necessary, the control unit 50 controls the EGR gas cooler 43 to increase the temperature of the EGR gas at the outlet of the EGR gas cooler 43 (step S7). Thereby, the consumption of energy for cooling the EGR gas in the EGR gas cooler 43 can be suppressed.
　一方、新気温度Ｔａから露点温度Ｔｅを引いた値が所定の第１上限値よりも小さい場合（ステップＳ６においてＹＥＳ）、ステップＳ８へ進む。ステップＳ８では、掃気ガスの温度Ｔｓから露点温度Ｔｅを引いた値が所定の第２上限値（例えば５°Ｃ）よりも小さいか否かを判定する。掃気ガスの温度Ｔｓから露点温度Ｔｅを引いた値が第２上限値よりも小さくない（大きい）場合（ステップＳ８においてＮＯ）、必要以上に露点温度Ｔｅが低いことになるため、制御部５０はＥＧＲガスクーラ４３を制御して、ＥＧＲガスクーラ４３の出口におけるＥＧＲガスの温度を上昇させる（ステップＳ７）。なお、第１上限値及び第２上限値は互いに同じ値であってもよく、別の値であってもよい。ただし、第１上限値は第１下限値よりも大きく、第２上限値は第２下限値よりも大きい。 On the other hand, when the value obtained by subtracting the dew point temperature T e from the fresh air temperature T a is smaller than the first upper limit value of the predetermined (YES in step S6), the process proceeds to step S8. In step S8, it is determined whether or not the value obtained by subtracting the dew point temperature T e from the temperature T s of the scavenging gas is smaller than a predetermined second upper limit value (e.g., 5 ° C). Minus the dew point temperature T e from the temperature T s of the scavenging gas is not smaller than the second upper limit value (large) (in step S8 NO), to become a dew point temperature T e is less than necessary, control The unit 50 controls the EGR gas cooler 43 to increase the temperature of the EGR gas at the outlet of the EGR gas cooler 43 (step S7). The first upper limit value and the second upper limit value may be the same value or different values. However, the first upper limit value is larger than the first lower limit value, and the second upper limit value is larger than the second lower limit value.
　また、掃気ガスの温度Ｔｓから露点温度Ｔｅを引いた値が第２上限値よりも小さい場合（ステップＳ８においてＹＥＳ）、ステップＳ１に戻ってステップＳ１乃至Ｓ８を繰り返す。同様に、ステップＳ４においてＥＧＲガスクーラ４３の出口におけるＥＧＲガスの温度を低下させた場合、及び、ステップＳ７においてＥＧＲガスクーラ４３の出口におけるＥＧＲガスの温度を上昇させた場合も、ステップＳ１に戻ってステップＳ１乃至Ｓ８を繰り返す。 When the value obtained by subtracting from the temperature T s of the dew-point temperature T e of the scavenging gas is smaller than the second upper limit value (YES in step S8), it returns to step S1 to repeat the steps S1 to S8. Similarly, when the temperature of the EGR gas at the outlet of the EGR gas cooler 43 is decreased in step S4, and when the temperature of the EGR gas at the outlet of the EGR gas cooler 43 is increased in step S7, the process returns to step S1. Repeat S1 to S8.
　制御部５０は、上記の制御を行うことにより、ＥＧＲガスが新気又は掃気ガスと接触しても凝結するおそれのない状態（不凝結状態）を維持することができ、かつ、ＥＧＲガスクーラ４３において不要なエネルギの消費を抑えることができる。 By performing the above control, the control unit 50 can maintain a state (non-condensed state) in which the EGR gas does not have a possibility of condensing even when it comes into contact with fresh air or scavenging gas, and in the EGR gas cooler 43 Unnecessary energy consumption can be suppressed.
　なお、上述した制御では、ステップＳ４においてＥＧＲガスクーラ４３のみを制御していたが、ＥＧＲガスクーラ４３のみの制御に代えて又はＥＧＲガスクーラ４３の制御とともにエアクーラ３１を制御してもよい。具体的には、上記のステップＳ４において、制御部５０はエアクーラ３１を制御し、エアクーラ３１の出口における新気の温度（新気温度）Ｔａを上昇させることによっても、ＥＧＲガスが新気又は掃気ガスと接触しても凝結しない不凝結状態を維持することができる。 In the above-described control, only the EGR gas cooler 43 is controlled in step S4. However, the air cooler 31 may be controlled in place of the control of only the EGR gas cooler 43 or together with the control of the EGR gas cooler 43. Specifically, in step S4 of the control unit 50 controls the air cooler 31, by increasing the fresh air temperature (new air temperature) T a at the outlet of the air cooler 31, EGR gas is fresh air or An uncondensed state that does not condense even when contacted with the scavenging gas can be maintained.
　ただし、新気温度Ｔａを上昇させると、エンジン本体１０の燃費が低下する。そのため、制御部５０は、ＥＧＲガスクーラ４３の制御のみで（ＥＧＲガスクーラ４３の最大冷却能力の範囲内で）不凝結状態を維持できる場合にはＥＧＲガスクーラ４３のみを制御し、ＥＧＲガスクーラ４３の制御のみで不凝結状態を維持できない場合にはＥＧＲガスクーラ４３及びエアクーラ３１の両方を制御するようにしてもよい。この構成によれば、新気温度Ｔａを極力上昇させないように制御できるため、エンジン本体１０の燃費の低下を抑えることができる。 However, increasing the fresh air temperature T a, the fuel consumption of the engine body 10 decreases. Therefore, the control unit 50 controls only the EGR gas cooler 43 and only controls the EGR gas cooler 43 when the non-condensing state can be maintained only by controlling the EGR gas cooler 43 (within the range of the maximum cooling capacity of the EGR gas cooler 43). If the uncondensed state cannot be maintained, both the EGR gas cooler 43 and the air cooler 31 may be controlled. According to this configuration, since it controls the fresh air temperature T a to prevent as much as possible is increased, it is possible to suppress deterioration in fuel consumption of the engine body 10.
　また、上記のＥＧＲユニット４０では、スクラバ４２の下流にＥＧＲガスクーラ４３が配置されていたが、スクラバ４２の上流にＥＧＲガスクーラ４３を配置してもよい。さらに、ＥＧＲユニット４０は、複数のスクラバ４２を有していてもよく、複数のＥＧＲガスクーラ４３を有していてもよい。例えば、ＥＧＲガスクーラ４３の上流に１段目のスクラバ４２（プリスクラバ）を設け、ＥＧＲガスクーラ４３の下流に２段目のスクラバ４２（メインスクラバ）を設けてもよい。このような構成であっても、ＥＧＲガスの温度Ｔｇ及び圧力Ｐｇを測定できれば、前述した制御と同様の制御を行うことができる。 In the EGR unit 40 described above, the EGR gas cooler 43 is disposed downstream of the scrubber 42, but the EGR gas cooler 43 may be disposed upstream of the scrubber 42. Further, the EGR unit 40 may have a plurality of scrubbers 42 or may have a plurality of EGR gas coolers 43. For example, a first-stage scrubber 42 (prescrubber) may be provided upstream of the EGR gas cooler 43, and a second-stage scrubber 42 (main scrubber) may be provided downstream of the EGR gas cooler 43. Even with this configuration, if measuring the temperature T g and the pressure P g of the EGR gas can be controlled similar to the control described above.
　なお、上記の実施形態では、制御部５０がエアクーラ３１、ＥＧＲガスクーラ４３、又はその両方を制御する場合について説明したが、この制御は作業者が行ってもよい。つまり、制御部５０はＥＧＲガスが凝結する可能性があるときに作業者に警告し、作業者がエアクーラ３１、ＥＧＲガスクーラ４３、又はその両方を制御するようにしてもよい。具体的には、制御部５０は、ＥＧＲガスと合流する新気の温度と掃気流路３０に供給されるＥＧＲガスの露点温度の差が所定の第１下限値以下となったとき、又は、エンジン本体１０に供給される掃気ガスの温度と掃気流路３０に供給されるＥＧＲガスの露点温度の差が所定の第２下限値以下となったとき、スピーカやディスプレイなどの報知機器に警報信号を発信してもよい。すなわち、図３のステップＳ３及びＳ５においてＮＯのとき、制御部５０はステップＳ４で所定の警報信号を発信するようにしてもよい。この場合であっても、作業者によるバルブ等の制御（操作）によって、ＥＧＲガスの凝結による凝縮水の発生を事前に防ぐことができる。 In addition, in said embodiment, although the control part 50 demonstrated the case where the air cooler 31, the EGR gas cooler 43, or both were controlled, this control may be performed by the operator. That is, the control unit 50 may warn an operator when the EGR gas may condense, and the operator may control the air cooler 31, the EGR gas cooler 43, or both. Specifically, when the difference between the temperature of the fresh air that merges with the EGR gas and the dew point temperature of the EGR gas supplied to the scavenging flow path 30 becomes equal to or less than a predetermined first lower limit value, When the difference between the temperature of the scavenging gas supplied to the engine main body 10 and the dew point temperature of the EGR gas supplied to the scavenging flow path 30 is equal to or less than a predetermined second lower limit value, an alarm signal is sent to a notification device such as a speaker or a display. May be sent. That is, when NO in steps S3 and S5 of FIG. 3, the control unit 50 may transmit a predetermined alarm signal in step S4. Even in this case, generation of condensed water due to condensation of EGR gas can be prevented in advance by control (operation) of a valve or the like by an operator.
１０　エンジン本体
２０　排気流路
３０　掃気流路
３１　エアクーラ
３５　ウォータミストキャッチャ
４１　ＥＧＲ流路
４２　スクラバ
４３　ＥＧＲガスクーラ
５０　制御部
１００　エンジンシステム DESCRIPTION OF SYMBOLS 10 Engine main body 20 Exhaust flow path 30 Scavenging flow path 31 Air cooler 35 Water mist catcher 41 EGR flow path 42 Scrubber 43 EGR gas cooler 50 Control part 100 Engine system

Claims (5)

  1. 　エンジン本体と、
    　前記エンジン本体から排出された排気ガスを外部に放出する排気流路と、
    　新気にＥＧＲガスを混合した掃気ガスを前記エンジン本体に供給する掃気流路と、
    　前記排気流路から抽出した排気ガスをＥＧＲガスとして前記掃気流路に供給するＥＧＲ流路と、
    　前記掃気流路に設けられ新気を冷却するエアクーラと、
    　前記ＥＧＲ流路に設けられＥＧＲガスを洗浄液で洗浄するスクラバと、
    　前記ＥＧＲ流路に設けられＥＧＲガスを冷却するＥＧＲガスクーラと、
    　前記掃気流路に供給されるＥＧＲガスの露点温度が、当該ＥＧＲガスと合流する新気の温度よりも低く、かつ、前記エンジン本体に供給される掃気ガスの温度よりも低い不凝結状態を維持するように、前記エアクーラ、前記ＥＧＲガスクーラ、又はその両方を制御する制御部と、を備えたエンジンシステム。     The engine body,
    An exhaust passage for discharging exhaust gas discharged from the engine body to the outside;
    A scavenging flow path for supplying a scavenging gas obtained by mixing EGR gas to fresh air to the engine body;
    An EGR flow path for supplying exhaust gas extracted from the exhaust flow path to the scavenging flow path as EGR gas;
    An air cooler that is provided in the scavenging flow path and cools fresh air;
    A scrubber provided in the EGR flow path for cleaning EGR gas with a cleaning liquid;
    An EGR gas cooler provided in the EGR flow path for cooling the EGR gas;
    Maintains a non-condensing state in which the dew point temperature of the EGR gas supplied to the scavenging flow path is lower than the temperature of fresh air that merges with the EGR gas and lower than the temperature of the scavenging gas supplied to the engine body An engine system comprising: a control unit that controls the air cooler, the EGR gas cooler, or both.
  2. 　前記制御部は、前記不凝結状態を維持するとともに、ＥＧＲガスと合流する新気の温度と前記掃気流路に供給されるＥＧＲガスの露点温度の差が所定の第１上限値を超えないように、かつ、前記エンジン本体に供給される掃気ガスの温度と前記掃気流路に供給されるＥＧＲガスの露点温度の差が所定の第２上限値を超えないように、前記エアクーラ、前記ＥＧＲガスクーラ、又はその両方を制御する請求項１に記載のエンジンシステム。 The control unit maintains the non-condensing state and prevents a difference between a temperature of fresh air that merges with the EGR gas and a dew point temperature of the EGR gas supplied to the scavenging flow path from exceeding a predetermined first upper limit value. And the air cooler and the EGR gas cooler so that the difference between the temperature of the scavenging gas supplied to the engine body and the dew point temperature of the EGR gas supplied to the scavenging flow path does not exceed a predetermined second upper limit value. The engine system according to claim 1, wherein the engine system is controlled.
  3. 　前記制御部は、前記ＥＧＲガスクーラの制御のみで前記不凝結状態を維持できる場合には前記ＥＧＲガスクーラのみを制御し、前記ＥＧＲガスクーラの制御のみで前記不凝結状態を維持できない場合には前記ＥＧＲガスクーラ及び前記エアクーラの両方を制御する、請求項１又は２に記載のエンジンシステム。 The control unit controls only the EGR gas cooler when the non-condensing state can be maintained only by controlling the EGR gas cooler, and the EGR gas cooler when the non-condensing state cannot be maintained only by controlling the EGR gas cooler. The engine system according to claim 1, wherein both the air cooler and the air cooler are controlled.
  4. 　エンジン本体と、
    　前記エンジン本体から排出された排気ガスを外部に放出する排気流路と、
    　新気にＥＧＲガスを混合した掃気ガスを前記エンジン本体に供給する掃気流路と、
    　前記排気流路から抽出した排気ガスをＥＧＲガスとして前記掃気流路に供給するＥＧＲ流路と、
    　前記掃気流路に設けられ新気を冷却するエアクーラと、
    　前記ＥＧＲ流路に設けられＥＧＲガスを洗浄液で洗浄するスクラバと、
    　前記ＥＧＲ流路に設けられＥＧＲガスを冷却するＥＧＲガスクーラと、
    　ＥＧＲガスと合流する新気の温度と前記掃気流路に供給されるＥＧＲガスの露点温度の差が所定の第１下限値以下となったとき、又は、前記エンジン本体に供給される掃気ガスの温度と前記掃気流路に供給されるＥＧＲガスの露点温度の差が所定の第２下限値以下となったとき、所定の警報信号を発信する制御部と、を備えたエンジンシステム。     The engine body,
    An exhaust passage for discharging exhaust gas discharged from the engine body to the outside;
    A scavenging flow path for supplying a scavenging gas obtained by mixing EGR gas to fresh air to the engine body;
    An EGR flow path for supplying exhaust gas extracted from the exhaust flow path to the scavenging flow path as EGR gas;
    An air cooler that is provided in the scavenging flow path and cools fresh air;
    A scrubber provided in the EGR flow path for cleaning EGR gas with a cleaning liquid;
    An EGR gas cooler provided in the EGR flow path for cooling the EGR gas;
    When the difference between the temperature of the fresh air that merges with the EGR gas and the dew point temperature of the EGR gas supplied to the scavenging flow path is equal to or less than a predetermined first lower limit value, or the scavenging gas supplied to the engine body An engine system comprising: a control unit that issues a predetermined alarm signal when a difference between a temperature and a dew point temperature of the EGR gas supplied to the scavenging flow path is equal to or less than a predetermined second lower limit value.
  5. 　エンジン本体と、
    　前記エンジン本体から排出された排気ガスを外部に放出する排気流路と、
    　新気にＥＧＲガスを混合した掃気ガスを前記エンジン本体に供給する掃気流路と、
    　前記排気流路から抽出した排気ガスをＥＧＲガスとして前記掃気流路に供給するＥＧＲ流路と、
    　前記掃気流路に設けられ新気を冷却するエアクーラと、
    　前記ＥＧＲ流路に設けられＥＧＲガスを洗浄液で洗浄するスクラバと、
    　前記ＥＧＲ流路に設けられＥＧＲガスを冷却するＥＧＲガスクーラと、を備えたエンジンシステムの制御方法であって、
    　前記掃気流路に供給されるＥＧＲガスの露点温度が、当該ＥＧＲガスと合流する新気の温度よりも低く、かつ、前記エンジン本体に供給される掃気ガスの温度よりも低い不凝結状態を維持するように、前記エアクーラ、前記ＥＧＲガスクーラ、又はその両方を制御する、制御方法。     The engine body,
    An exhaust passage for discharging exhaust gas discharged from the engine body to the outside;
    A scavenging flow path for supplying a scavenging gas obtained by mixing EGR gas to fresh air to the engine body;
    An EGR flow path for supplying exhaust gas extracted from the exhaust flow path to the scavenging flow path as EGR gas;
    An air cooler that is provided in the scavenging flow path and cools fresh air;
    A scrubber provided in the EGR flow path for cleaning EGR gas with a cleaning liquid;
    An engine system control method comprising: an EGR gas cooler provided in the EGR flow path for cooling EGR gas;
    Maintains a non-condensing state in which the dew point temperature of the EGR gas supplied to the scavenging flow path is lower than the temperature of fresh air that merges with the EGR gas and lower than the temperature of the scavenging gas supplied to the engine body A control method for controlling the air cooler, the EGR gas cooler, or both.
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