# US 4,394,813 A · Exhaust gas heat recovery system in internal combustion engine

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- Number: US 4,394,813 A
- Document ID: US4394813A
- Status: Granted
- Kind: A
- Application number: 06/304,600
- Filed: 1981-09-22
- Granted: 1983-07-26
- Earliest claimed: 1980-12-25
- Assignees: Mitsui Engineering & Shipbuilding Co., Ltd.
- Inventors: Yoshiharu Tanaka; Yoshiaki Watanabe; Kou Sasaki
- Web page: https://patentgrep.com/patent/US4394813A

## CPC

- F22B 37/025: {Devices and methods for diminishing corrosion, e.g. by preventing cooling beneath the dew point}
- F01K 7/18: the turbine being of multiple-inlet-pressure type
- F01K 23/065: {the combustion taking place in an internal combustion piston engine, e.g. a diesel engine}
- F01K 23/10: with exhaust fluid of one cycle heating the fluid in another cycle (F01K17/025 takes precedence)
- F02G 5/02: Profiting from waste heat of exhaust gases
- Y02T 10/12: Improving ICE efficiencies
- F22B: METHODS OF STEAM GENERATION; STEAM BOILERS
- F01K: STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES (gas-turbine or jet-propulsion plants F02; nuclear power plants, engine arrangements therein G21D)
- F02G: HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS (steam engine plants, special vapour plants, plants operating on either hot gas or combustion-product gases together with other fluid F01K; gas-turbine plants F02C; jet-propulsion plants F02K); USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

An exhaust gas heat recovery system wherein: the system comprises an exhaust gas economizer having of heat transfer sections including a preheating section, an evaporating section and a superheating section, a feed water heater, a steam separation drum, a low pressure steam generator; and a mixed-pressure turbine; a temperature gradient of circulating water and a temperature gradient of exhaust gases are made substantially equal to each other in the preheating section of the exhaust gas economizer to prevent an exhaust gas economizer tube from being corroded by generated sulfuric acid; and low pressure steam can be effectively utilized by use of the mixed-pressure turbine.

## Claims

### Claim 1

An exhaust gas heat recovery system in an internal combustion engine, comprising: an exhaust gas economizer having heat transfer sections including a preheating section, an evaporating section and a superheating section; a feed water heater for heating water fed to said heat transfer sections of the exhaust gas economizer; a steam separation drum for separating steam and saturated water from fluid of steam-water mixture discharged from the exhaust gas economizer; a mixed-pressure turbine having a high pressure side and a low pressure side, a piping for feeding part of the steam separated in said steam separation drum to said superheating section of the exhaust gas economizer and further transferring said steam to the high pressure side of said mixed-pressure turbine; a piping for feeding part of the saturated water separated in said steam separation drum to said feed water heater and said evaporating section of the exhaust gas economizer, respectively; a low pressure steam generator provided in said piping for returning the saturated water separated in said steam separation drum to said feed water heater; a piping for feeding low pressure steam in said low pressure steam generator to the low pressure side of said mixed-pressure turbine; and a piping for condensing exhausted steam from the mixed-pressure turbine in a condenser and thereafter circulating the water thus condensed to said feed water heater.

### Claim 2 (depends on 1)

An exhaust gas heat recovery system in an internal combustion engine as set forth in claim 1, wherein said feed water heater is a mixing type feed water heater.

### Claim 3 (depends on 1)

An exhaust gas heat recovery system in an internal combustion engine as set forth in claim 1, wherein a control valve is provided at the intermediate portion of a piping interconnecting a low pressure steam generator and the steam separation drum.

### Claim 4 (depends on 3)

An exhaust gas heat recovery system in an internal combustion engine as set forth in claim 3, comprising means for feeding a part of the saturated water separated in said main steam separation drum to the evaporating section of the exhaust gas economizer through said control valve.