JPS594536B2 - Internal combustion engine with exhaust gas recirculation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an internal combustion engine with an exhaust gas recirculation device.

According to the invention, the method of operating an internal combustion engine with an exhaust gas recirculation device comprises a process of supplying the engine with hydrocarbon fuel and pure oxygen, recirculating the exhaust gas from the outlet manifold of the engine to the inlet manifold of the engine. a step of treating at least a portion of the exhaust gas of the recirculation step to liquefy CO2, and a step of removing liquefied CO□ from the recirculation gas.

The internal combustion engine of the present invention includes a hydrocarbon fuel supply means, a pure oxygen supply means in communication with the engine inlet manifold, and a gas recirculation device for recirculating exhaust gas from the engine outlet manifold to the engine inlet manifold. The apparatus includes means for liquefying 002 from at least a portion of the recycled exhaust gas and means for removing liquefied CO2 from the exhaust gas.

Since the only components fed to the engine of the invention are oxygen and hydrocarbon fuel, the exhaust gas recirculated to the engine contains exclusively unburned oxygen, CO and the unliquefied remainder of CO□. Certain points will be appreciated.

Although the entire amount of CO2 gas contained in the exhaust gas can be removed from the exhaust gas by the method of the present invention, the method of the present invention also removes the CO2 gas contained in the exhaust gas.
It is also possible to use only a portion of the CO2 gas, thereby removing the remaining CO2 gas and passing it through the engine again.

The non-recirculated C02 gas may be removed from the exhaust gas in liquefied form and stored in storage means suitable for this purpose or pumped into the atmosphere.

The internal combustion engine of the present invention requires that the power energy be generated from liquid hydrocarbon fuel (due to the unavailability of an adequate supply of electrical energy from external sources) and that the emissions leaving the internal combustion engine are It is particularly convenient for use in sealed enclosures when release to the atmosphere is not possible.

By using an internal combustion engine that operates on a mixture of hydrocarbon fuel and pure oxygen, CO2 is the only emission that must be disposed of.

With the technique of the invention, the C02 gas is removed from the exhaust gas in liquefied form and therefore requires only a small space for storage.

This internal combustion engine is therefore very suitable for use in sealed locations where exhaust gases must not or cannot escape.

The internal combustion engine of the present invention also provides liquefied C when used in underwater operations.
Since it can be pumped from a diving bell into the surrounding (high pressure) water at a relatively low cost, it can be placed in a diving bell and used advantageously for underwater work.

The invention will now be explained in more detail with reference to embodiments shown diagrammatically in the accompanying drawings, in which: FIG.

In FIG. 1, only one cylinder of a reciprocating internal combustion engine 2 is shown diagrammatically.

Engine 2 includes an outlet manifold 3 and an inlet manifold 4, which include a cooler 6, a compressor 7, a cooler 8, a separator 9, a control valve 10, and a heater 11, all of which are interconnected as shown. They communicate with each other via recirculation devices connected by conduits.

The direction of fluid flow through these conduits is indicated by arrows 12.

A short circuit conduit 13 is provided in the recirculation device 5, this short circuit bypassing the compressor 7, the chilled book separator 9 and the control valve 10.

The fluid passing through the shorting conduit 13 is directed in the direction of arrow 14;
The ratio of flow rates through the short circuit 13 and the short circuit of the recirculation device 5 is controlled by a valve 15.

Separator 9 has two outlets.

The first outlet 16 communicates with the recirculation line 5 and is used to deliver substantially CO2-free exhaust gas to the engine 2, as will be explained in more detail below.

A second outlet 17 directs liquefied CO2 to conduit 18 and pump 1
9 to the storage tank 20 for liquefied CO2.

This storage tank is preferably of a pressure-resistant type.

The liquid oxygen storage tank 21 communicates with the recirculation line 5 by a conduit 22 and through this line into the inlet manifold 4 of the engine 2 .

The fuel storage tank 23 is connected to the engine 2 via a conduit 24.

The details of the fuel injection system of the engine 2 are not shown as these are self-explanatory.

A fuel flow measuring device 25 is provided in conduit 24 and a signal representative of the fuel flow rate is sent via signal path 27 to a controller 26.

The controller further connects the gas passing through the short circuit 13 and the circuit 12
A signal is received representative of the oxygen content in a gas mixture consisting of gases originating from the gas mixture.

These latter signals originate from the oxygen content measuring means 28 and are transmitted via a signal path 29 to the controller 26.

The controller 26 determines that the amount of oxygen delivered to the engine 2 from the reservoir 21 depends on the fuel flow rate requested by the engine 2 and the amount of oxygen already present in the mixture of C02 and 0□ coming from circuits 13 and 16.
The control valve 10 is controlled in such a way that it always meets 2%.

Next, the operation of the internal combustion engine shown in FIG. 1 will be explained.

Fuel is supplied to the engine 2 from a fuel reservoir 23, and pure oxygen is supplied after evaporation from the oxygen reservoir 21 through a conduit 22 and a portion of the recirculation line 5 to the inlet manifold 4 of the engine 2.

The engine 2 is started and the exhaust gas containing CO□, H2O1, unburned 02 and other combustion products is discharged through the outlet manifold 3 into the recirculation line 5.

These exhaust gases pass through a water-cooled heat exchanger 6 (in which the gases are also cleaned) and are then divided into two separate streams by a valve 15.

The portion of the exhaust gas recirculation system 5 that passes through the short circuit first enters the compressor 7 where the pressure is increased to a level sufficient to cause liquefaction of the 002 in the cooler 8.

The mixture of liquefied CO2 and unliquefied exhaust gas then passes through a separator 9 where the liquefied CO2 is separated from the gas and sent through an outlet 17 to a pump 19 and the liquefied C02 is fed into a storage tank 20 via a conduit 18. The CO□ is then stored there under conditions of pressure and temperature adjusted to keep the CO□ in liquid form.

The exhaust gas, which has been at least partially freed from CO2, is directed to the inlet manifold 4 of the engine 2 via the outlet 16 of the separator 9.

On its way to this inlet manifold, this gas is first mixed with a fresh feed of pure oxygen obtained by evaporation of an equivalent portion of liquid oxygen stored in the oxygen reservoir 21.

The evaporated oxygen gas flows through the conduit 22 into the recirculation line 5 and is mixed with the gas coming from the separator 9 before being passed through the control valve 1.
0 and is then mixed by conduit 13 with the exhaust gas which is the short circuit part of the recirculation system.

The resulting gas mixture then passes through device 28 for measuring the oxygen content.

After the % of oxygen can be monitored, the mixture is transferred to engine 2.
is heated by a heater 11 before entering the inlet manifold 4.

After this mixture enters the cylinder of the engine 2, it enters the fuel tank 23.
The exhaust gas produced is recirculated through the recirculation line 5 as described above.

By controlling the valve 15, the amount of exhaust gas that is not subjected to CO7 removal treatment can be adjusted.

The amount of oxygen supplied by the oxygen supply means 21 to replenish the oxygen consumed in burning fuel in the engine 2 is equal to the amount of oxygen contained in the gas supplied to the inlet manifold 4. is controlled by the control valve 10 in relation to the amount of fuel supplied to the engine 2.

The cooling fluid that cools the gas stream passing through the cooler 6 may be of any suitable nature, such as seawater or CO2.
It may also be a refrigerant used in a cooling circuit used to liquefy a gas.

The latter method will be explained later with reference to FIG.

Compressor 7 may be of any type suitable for this purpose.

It may be driven either by the internal combustion engine 2 or by another prime mover (not shown).

The compression of the gas passing through the compressor 7 is such as to liquefy most of the CO2 component of this gas when it is passed through the cooling process in the cooler 8 installed in series with the compressor 7. It must be of sufficient altitude.

This cooler 8 is formed by any type of heat exchanger suitable for this purpose and forms part of a refrigeration system (either a vapor compression or an absorption refrigeration system).

The heater 11 brings the temperature of the recirculated and cooled exhaust gas and pure oxygen gas (formed by evaporation of liquid oxygen) to the desired value necessary for sufficient combustion of the fuel in the cylinder 1 of the engine 2. used for elevating.

Any fluid suitable for this purpose can be used to heat this gas in heater 11.

The fluid may be exhaust gas discharged from the outlet manifold 3 of the engine 2.

This fluid may also be cooling water that is passed through the engine 2 to cool the walls of the cylinders 1 of the engine 2.

Advantageously, temperature control means are provided for controlling the temperature of the gas leaving the heater 11.

The above temperature control involves bringing at least a portion of this cooling water into heat exchange contact with a relatively low temperature fluid, such as ambient air or water (for example, when using the engine 2 inside a deep-sea diving bell). This includes controlling the temperature of the cooling water for the machine by passing water through it.

Furthermore, the electrical power means may be arranged in the heater 11 or in another heater (not shown) installed in series with the heater 11.

Next, another side of the internal combustion engine of the present invention will be explained with reference to FIG.

The internal combustion engine 30 is of the reciprocating type and includes an outlet manifold 31 which is separated from the outlet section of each cylinder (which is not sooted) and by a conduit 32 leading to a boiler 33 of a ψ refrigeration system to be described below.

The conduit 32 leads, via suitable heat exchange means in the boiler 33, to a conduit 34 which leads to a gas scrubbing device 35 in which the gas is brought into intimate contact with the water supplied via the supply conduit 36. ing.

After carrying out the cleaning action (to reduce the temperature of the gun and remove all solids and shuttle impurities from the gas), water is discharged via conduit 37.

Gas cleaning device 35 (inside 17, through conduit 38, conduit 3
It communicates with a valve 39 which is arranged to divide the gun flow passing through 8 into conduits 40 and 41.

The gas passing through conduit 40, which may be of any suitable type, enters dryer 42 and then passes through cooler 43 and is drained.

Cooling liquid is supplied to this cooler 43 via conduit 44 and is discharged via conduit 45.

Any suitable coolant source available for cooling purposes can be used.

After cooling, the exhaust gas is passed through a compressor 47 where at least a large portion of the CO□ component in the gas is transferred to coolers 48 and 4.
The exhaust gas is compressed to a pressure sufficient to be liquefied at step 9.

Cooler 48 is a precooler through which fluid is passed (through inlet 50 and outlet 51) at a relatively low temperature.

However, the cooler 49 forms part of an absorption refrigeration system, as already explained, which brings it to a temperature low enough to liquefy most of the CO□ contained in the exhaust gases coming from the engine 30. It is arranged to cool the gas passing through it.

The liquid CO2 and gaseous oxygen then flow through conduit 52 to a separator 53, where the liquid CO2 is separated from the gas, and the liquid CO2 is passed through a pump 54 in the middle of conduit 55.
2 is sent to a storage tank 56 which is provided to store .

The remaining gaseous mixture consisting of CO2 and oxygen is transferred to tank 58.
It exits the separator 53 through a conduit 57 leading to.

In this tank, the treated exhaust gas is fed through conduit 59 to tank 58 and supplemented with gaseous oxygen generated from a liquid oxygen source 60.

The resulting gas mixture is passed through conduit 62 to a regulating valve 61 which controls the supply of the gas mixture through conduit 41 (through conduit 41) to the exhaust gas main stream, thereby adjusting the required amount at inlet lower 2 of engine 30. Ensure pressure.

The main stream of this exhaust gas is passed through the dryer 42, the cooler 43, and the compressor 4.
7, short-circuiting the gas treatment device including the coolers 48, 49 and the separator 53 and passing through the conduit 41 to the mixing device 6.
3.

The gas mixture produced after mixing passes through a conduit 64 to a measuring means 65 adapted to measure the oxygen content in the mixture and then flows via a conduit 66 to a heater 67 where the mixture is is heated to an appropriate temperature.

Heater 67 is operated by passing a relatively hot fluid through it.

This fluid is introduced into heater 67 through conduit 68 and discharged via outlet 69.

An electrically operated auxiliary heater 70 communicates with heater 68 via conduit 71 .

This auxiliary heater can be used either in place of the Calo heater 67 or to support the heating action of the heater 67.

Gas is then supplied via conduit 73 to inlet manifold 72 of engine 30.

Fuel is supplied to engine 30 from fuel reservoir 75 via conduit 74 leading to a suitable engine portion (not shown) for distributing fuel fluid within the cylinders of engine 30.

The fuel flow rate is measured by measuring means 76, which sends a signal via line 77 to a controller 78 indicating the fuel flow rate.

This controller 78 further receives signals from the oxygen content measuring means 65 via line 79 and controls a control valve 61 via line 80 to control the amount of the treated exhaust gas and the pure water added thereto. The supply of the gas mixture consisting of oxygen is adjusted in such a way that it is sufficient to provide a product gas mixture in conduit 66 with an oxygen content followed by the fuel flow rate.

The recirculation system shown in Figure 2 includes power heating means 33 and cooling means 49 forming part of an absorption refrigeration system.

The boiler 33 of this refrigeration system communicates with the absorber 83 via conduits 81 and 82.

Fluid flow through the refrigeration system is indicated by arrows.

After leaving boiler 33 via conduit 84, the refrigerating fluid passes through rectifier 85, conduit 86, cooler 81, conduit 88 and evaporator 49, and from evaporator 49 via conduit 89 to absorber 83. be returned.

The cooler 87 includes an inlet 90 and an outlet 91 for cooling fluid and may be of any type suitable for this purpose.

Absorption refrigeration systems are known per se, and the refrigeration system shown in FIG. 2 does not need to be described in further detail.

During operation of an internal combustion engine equipped with an exhaust gas recirculation device as shown in FIG. It is possible to control the ratio of exhaust gas that is recycled to the engine 30 and untreated (excluding heating in heaters 67 and 70).

Valve 39 can be designed to automatically control this ratio so that the absolute pressure in recirculation conduit 41 is held constant.

As shown in FIG. 1, control valve 15 is conveniently operated in a manner similar to that described with respect to control valve 39 above.

The internal combustion engine of the invention can be most advantageously used in submarines or diving bells.

Advantageously, all of the liquid components used in prime movers 2 and 30 are not discharged from the various circuits, so their overall weight remains unchanged, and separate ballast controls for the submarine or diving bell are not required. it is obvious.

However, if the above-mentioned separate ballast control is not considered to be a significant issue, the liquefied CO□ need not be stored in liquefied form, but rather discharged into the surrounding water and discharged through the exhaust gas recirculation system. can be done.

Since engine emissions are in liquid form insofar as they react with oxygen to form CO2, they are relatively small compared to the volume of CO3 components in the exhaust gas after leaving the engine. The pumping energy required to remove CO2 from a ship or diving bell, which occupies a small volume and especially when the ship or diving bell operates in deep water, is
Compared to the energy required to pump O2 to waste against the high external pressures exerted outside the submarine or diving bell, it is obviously advantageous to release much less liquefied CO2. This is a good thing.

A further advantage of the exhaust gas recirculation system of the present invention is that in engines equipped with an exhaust gas recirculation system, the compression ratios allowed are relatively high in order to improve the thermodynamic efficiency of the engine. .

It is recognized that compression ratios that are considerably higher than those normally used in internal combustion engines using air as the working gas and combustible carrier are acceptable in internal combustion engines.

This relatively high allowable compression ratio is due to the different thermodynamic properties of air and the mixture of CO2 and oxygen, and in particular the Cp/C of nitrogen (which is the main gaseous component of air) vs.
This is the result of different Cv values.

By using an internal combustion engine that can operate on either recirculated gas or fresh air, low compression is required to avoid overstressing the engine components during periods when the engine is running on fuel supplied to the engine by fresh air. ratio must be applied.

However, the use of the above-mentioned engine in combination with an exhaust gas recirculation system results in very low operating efficiency due to the low temperature obtained at top dead center.

However, by designing an engine only for CO2 and oxygen as combustible carriers, high compression ratios (e.g. 18 or higher, e.g. 28-28
55), the top dead center temperature is CO
When a mixture of □ and oxygen is used as the working gas and combustible carrier, the loads on engine components (eg, shafts, bearings, pistons, and ronds) are not unduly high, but temperatures are sufficient to cause combustion.

The compression ratio of the mixture of CO□ and oxygen is 55 and the compression ratio is 17.
5 was found to reach the same top dead center temperature as using air.

At that time, the maximum pressure was 100% higher.

As a result of experimental research on individual engines, it has been found that the optimum values are approximately the same at a compression ratio of 30.

The invention is not limited to the use of any particular type of engine.

The engine may be reciprocating, such as a commercially available diesel or ignited internal combustion engine.

However, if desired, the agency may also, for example,
n k e l ) A rotary type engine such as a J-type internal combustion engine may be used.

Furthermore, the present invention provides a special cooling technology used to cool the compressed exhaust gas to a temperature low enough to cause liquefaction of a small portion of the CO2 component contained in the exhaust gas. or the application of the device.

The refrigeration system comprises a vapor compression or condensation refrigeration system of any suitable construction.

All other heat exchange equipment used to treat the recirculated exhaust gas and pure oxygen (unlike the cooling means for liquefying the C02) may be of conventional type, suitable for this purpose and available. Any cooling and heating fluid can be used.

Therefore, when the invention is used on a submarine or diving bell, it is obvious to use relatively cold sea water for cooling, since sea water is available in abundance in this case.

If necessary, a filter is inserted into the cooling water supply pipe.

If desired, valves for closing the various conduits of the recirculation device and its short circuits can be provided at convenient locations on the recirculation device.

The same applies to safety controls used to prevent overheating, cooling and overpressurization.

Pressure reducers and non-return valves are also used in the conduits to ensure that fluid flow flows in the correct direction through these conduits.

Therefore, it is preferable to introduce pressure reduction means into the conduit 62 using the flow sheet shown in FIG.

Furthermore, any type of storage tank for storing liquid fuel, liquid oxygen and liquid CO2 can be used.

A double-walled toroidal storage tank is preferably used to store the liquefied gas at the desired low temperature and high pressure.

The space between the walls is preferably evacuated to increase the thermal insulation of the reservoir.

1 and 2 and that the controller installed for controlling the supply of oxygen to the untreated recirculated exhaust gas may be of any type suitable for this purpose. it is obvious.

The control functions are provided by a computer which is either specially designed for this purpose or which forms part of a computer center performing various functions on a ship or diving bell equipped with an internal combustion engine of the invention. It can be implemented.

The measuring device may be of any type suitable for this purpose.

Flow rate measuring means (instruments 25 and 7 in Figures 1 and 2)
6) may be constituted by a fuel injection pump.

The oxygen content measuring means (see 28 and 65 in Figures 1 and 2 respectively) also measures the CO of the gas passing therethrough.
2 content may be included.

In summary, it is clear that the internal combustion engine of the present invention requires only oxygen and hydrocarbon fuel for its operation.

Since no air is required, the engine can be used in a sealed enclosure, all the more so since all engine exhaust can be liquefied and stored in the enclosure.

Under special circumstances, the engine's effluent may be discharged in only small amounts, even if the enclosure is located in an area of high pressure (e.g. at the bottom of a sea or ocean), since it is in the liquid phase. It is possible to dispose of this from a sealed enclosure with only energy consumption.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the basics of the internal combustion engine of the present invention, and FIG. 2 is a more detailed diagram. 1...Cylinder, 2...Internal combustion engine, 3...
... Outlet manifold, 4... Inlet manifold, 5... Recirculation device, 6... Cooler, 7... Compressor, 8... ...Cooler, 9.
...Separator, 10...Control valve, 11...
... Heater, 12 ... Circuit, 13 ...
...Short conduit, 14...Arrow, 15...
・Valve, 16...outlet, 17...outlet,
18... Conduit, 19... Pump, 20
... CO2 storage tank, 21 ... Liquid oxygen storage tank, 22 ... Conduit, 23 ... Fuel storage tank, 24 ... Conduit, 25. ... Fuel flow rate measuring device, 26 ... Controller, 27 ... Signal path, 28 ... Oxygen content measuring means, 29 ...
...Signal road, 30...Internal combustion engine, 31...
... Outlet manifold, 32 ... Conduit, 33
...Boiler, 34... Conduit, 35.
... Gas cleaning device, 36 ... Supply conduit,
37... Conduit, 38... Conduit, 39.
... Valve, 40 ... Conduit, 41 ...
- Conduit, 42... Dryer, 43... Cooler, 44... Conduit, 45... Conduit,
46... Conduit, 47... Compressor, 48
...Cooler, 49...Cooler, 50.
...Entrance, 51...Exit, 52...
... Conduit, 53 ... Separator, 54 ...
pump, 55... conduit, 56... storage tank, 57... conduit, 58... tank, 59.
... Conduit, 60 ... Liquid oxygen supply source, 6
1... Control valve, 62... Conduit, 63.
... Mixing device, 64 ... Conduit, 65 ...
... Measuring means, 66 ... Conduit, 67 ...
... Heater, 68 ... Conduit, 69 ...
・Outlet, 70... Auxiliary heater, 71...
・Conduit, 72... Inlet manifold, 73...
... conduit, 74... conduit, 75...
Fuel tank, 76... Measuring means, 77...
Conduit, 78... Controller, 79... Conduit, 80... Conduit, 81... Conduit, 82
... Conduit, 83 ... Absorber, 84 ...
... Conduit, 85 ... Rectifier, 86 ...
... Conduit, 87 ... Cooler, 88 ...
Conduit, 89...Conduit, 90...Inlet,
91...Exit.

Claims (1)

[Claims] 1. An internal combustion engine having a hydrocarbon fuel supply means, a pure oxygen supply means in communication with an inlet manifold of the internal combustion engine, and a gas recirculation device for recirculating exhaust gas from the outlet manifold of the internal combustion engine to the inlet manifold of the internal combustion engine. wherein the gas recirculation device includes means for liquefying CO2 from at least a portion of the recirculated exhaust gas;
means for removing O2 from the exhaust gas, and further comprising means within the internal combustion engine for measuring the oxygen content in the gas recirculation system "in the part closest to the internal combustion engine inlet manifold"; means for measuring the flow rate of fuel entering the engine; valve means for controlling the passage between the pure oxygen supply means and the internal combustion engine inlet manifold; and for controlling said valve means operated in conjunction with said measuring means. An internal combustion engine characterized in that it is also provided with a control means.