Double-circuit gas recirculation system of an internal combustion engine with gas turbine supercharging

The invention relates to engine construction, in particular, the exhaust gas part (Exhaust gas) recirculation system according to a two-circuit scheme, which is used in accordance with the proposed invention, as well as to a gas turbine supercharged diesel engine recirculation control system, where the recirculated gases are discharged from the exhaust system (ICE) of a vehicle through a dual-circuit exhaust gas recirculation system (EG) of a gas turbine supercharged internal combustion engine in the intake manifold turbocharger cuts.

Turbocharging is the primary means of increasing the torque and power of an internal combustion engine. Exhaust gas recirculation is a common means for improving the quality of exhaust gases, i.e. reducing the content of nitrogen oxides and other harmful substances in the exhaust gases. When combining exhaust gas recirculation along an external circuit, i.e. when directing some of the exhaust gases from the engine exhaust manifold to the engine intake manifold with a turbocharger, it is necessary to increase the pressure of the exhaust gases recirculated to the intake manifold to a pressure level that is at least the same as the charge air pressure in the intake manifold .

In conventional systems that regulate the specified parameters of nitrogen oxides in a diesel engine, part of the exhaust gases are recirculated from the vehicle exhaust system to the compressor inlet of the turbocharger and regulate the flow of fresh air and recirculated exhaust gases to the diesel engine through the design of a double-circuit exhaust gas recirculation system, operation which is regulated by the coordinated work of two-position and multi-position dampers controlled by ktronnym control unit.

In order to reduce the content of emissions of harmful substances from exhaust gases, especially nitrogen oxides (NO_x), exhaust gas recirculation systems have been used for many years in many types of internal combustion engines. Such systems make it possible to recirculate part of the exhaust gases into the engine intake system, where they mix with the intake air and are fed further into the engine's combustion chamber. Recirculating exhaust gases replace part of the intake air and reduce the NO content._x in the exhaust gases of the car.

Information is fed to the control device from the engine crankshaft speed sensor and the engine load sensor in order to adjust the air / fuel ratio in the internal combustion engine.

Known exhaust gas recirculation system of an internal combustion engine, presented in US patent US 7979196 B2, applicant CATERPILLAR INC, publ. 12.07.2011, where exhaust gas is recirculated through an external circuit, with recirculating gases taken from the diesel particulate filter and the exhaust gas treatment system, recirculating gases are supplied through a heat exchanger to the inlet of the turbocharger compressor. Such a single-circuit scheme reduces the possibilities and lowers the efficiency of the use of the engine system due to the insufficiency of recirculation drops and high gas temperatures when recirculating gases along the recirculation circuit. The single-circuit system is effective only at full load, when the recirculation pressure drop is high at high loads and speeds.

The analogue of the presented technical solution of the engine exhaust gas recirculation system is US patent number US6899090 B2, applicants ARNOLD STEVEN DON, HONEYWELL INTERNATIONAL, INC., Publ. 05/31/2005, where exhaust gas is recirculated through an external circuit, with recirculating gases taken after the diesel particulate filter and other components of the exhaust after-treatment system. Such a scheme reduces the possibilities and lowers the efficiency of use of the engine system due to the insufficiency of recirculation drops in low and medium load modes and rotational frequencies. The single-circuit system is effective only at full load and high engine speeds when the recirculation pressure drop is high. In other engine operating modes, the exhaust gas recirculation system,

Closest to the invention to the technical essence and the achieved result is the exhaust gas recirculation system of an internal combustion engine with two gas recirculation circuits, presented in US patent No. US 9624874 B2, the applicant DOOSAN INFRACORE CO., LTD publ. 04/18/2017, where the exhaust gas recirculation is carried out on the external circuit, but with the selection of recirculating gases after the turbine compressor output and to the exhaust gas after-treatment system. When the engine operates at partial loads (low speeds and low and medium loads), the efficiency of the recirculation system is extremely low due to the limited charge air consumption.

High-charged internal combustion engines of vehicles of the CU, using natural gas as fuel, operate under all operating conditions with the values ​​of the coefficient of excess air 1.5 ... 5 times smaller compared with those of diesel engines. As a result, the exhaust temperature of the first by 150 ° ... 300 higher than that of the second. In the invention, adopted for the prototype, the scheme of passage of recirculating gases, consisting of external and internal intercollector circuits of passage of recirculating gases with their own means of cooling on each of the circuits and the general cooling system for the main recirculation channel, described in the prototype, is meaningless in the case of high-loaded vehicles because the efficiency of the internal intercollector circuit is close to zero due to the low recirculation difference,

An internal combustion engine system with a vehicle exhaust system and loop recirculation form an engine recirculation system. The exhaust gas recirculation system on the external circuit returns part of the exhaust gases to the cylinders of a diesel internal combustion engine. Increasing the proportion of triatomic gases (CO₂H₂O) increases the heat capacity of the charge, which leads to a decrease in the temperature of combustion and a decrease in the amount of nitrogen oxides NO_x in exhaust gases.

The objective of the proposed invention is to increase the efficient operation of the exhaust gas recirculation system in all engine operating modes, while achieving the following technical results: reducing emissions of nitrogen oxides, hydrocarbons, suspended particles and improving fuel efficiency by expanding the capabilities of the range of use of exhaust gas recirculation around the outside operating modes of the engine, this increases the efficiency of the engine system, its compactness, durability awn exchanger recirculated gases.

This technical problem is solved by the fact that a dual-circuit exhaust gas recirculation system (EG) of a gas turbine supercharged internal combustion engine contains pipeline-controlled means for controlling gas exchange of exhaust gases of the internal combustion engine and air entering the engine, an electronic control unit for gas exchange control means, a turbo compressor, an exhaust gas processing unit, located in the exhaust pipe after the turbocharger, and two exhaust gas recirculation circuits communicated with a cooling exchanger recirculating gases, the system is provided with means for controlling gas exchange in the form of at least three and two multiposition two-position valves and two multiposition valves are arranged on the exhaust path, and the third - mainly recirculation channel, The primary exhaust gas recirculation loop inlet is located after the exhaust gas treatment unit, up to the second multi-position damper, and the primary exhaust gas recirculation loop output is connected to the main recirculation channel with adjustable first dual damper, the secondary exhaust gas recirculation inlet is located downstream of the turbocharger to the first multi-position damper and to the unit exhaust gas treatment, and the output of the secondary circuit recirculation of exhaust gas communicated with the main recirculation channel with the possibility of regulating its second vuhpozitsionnoy damper, wherein the main recirculation channel is connected to the inlet path with the possibility of regulating the third multiposition valve. and the output of the primary exhaust gas recirculation circuit is in communication with the main recirculation channel with the ability to control the first on-off valve, the input of the secondary exhaust gas recirculation circuit is located after the turbine of the turbocompressor to the first multi-position damper and to the exhaust gas processing unit, and the output of the secondary exhaust gas recirculation circuit is connected to the main recirculation channel with possibility regulation of its second two-way valve, the main recirculation channel is connected to the intake tract with the ability to regulate the third multi-position damper. and the output of the primary exhaust gas recirculation circuit is in communication with the main recirculation channel with the ability to control the first on-off valve, the input of the secondary exhaust gas recirculation circuit is located after the turbine of the turbocompressor to the first multi-position damper and to the exhaust gas processing unit, and the output of the secondary exhaust gas recirculation circuit is connected to the main recirculation channel with possibility regulation of its second two-way valve, the main recirculation channel is connected to the intake tract with the ability to regulate the third multi-position damper.

The technical result is achieved as a result of creating a dual-circuit multi-mode exhaust gas recirculation system for each circuit, by combining sections of the recirculation circuits to ensure that recirculating gases can pass through the heat exchanger for recirculating gases common to all recirculation circuits.

When the engine is not running or the gas engine is started at idle, both gas recirculation circuits are blocked, all two-position and third multi-position dampers are closed.

At low and medium loads at low and medium frequencies of rotation of the gas and diesel engines, a second small gas recirculation circuit operates with the selection of recirculating gases to the exhaust gas treatment unit of the exhaust gas cleaning system. Recirculating gases in these modes at elevated, relative to the first circuit, recirculation drops come from the turbine outlet through the second small gas recirculation loop to the compressor inlet and further to the internal combustion engine. Increased pressure drops of recirculating gases are achieved by a corresponding intermediate position of the multi-position dampers, which is set using a signal from the electronic control unit.

At high loads at high speeds of diesel and gas engines, i.e. At high air flow rates, the first large gas recirculation circuit works, which allows for supplying a sufficient volume of recirculation gases with high efficiency with a high flow rate of the fuel-air mixture. At the same time, completely purified recirculated gases are taken from the output of the exhaust gas treatment unit of the post-treatment system. , which allows to achieve an additional technical result, which lies in the fact that extends the service life and efficient operation of the total for Vuh contours of the heat exchanger cooling recirculating gases, located on the main recirculation channel.

The description is illustrated by drawings.

The figure 1 shows the engine system with the location of its valves in the first position.

The figure 2 shows the engine system with the location of its valves in the second position.

The figure 3 shows the engine system with the location of its valves in the third position.

The figure 4 shows schematically the electrical connection of the control devices that set the mode of operation of the electronic control unit and all valves.

The two-circuit exhaust gas recirculation system (exhaust gas) of a gas turbine supercharged internal combustion engine contains pipeline-connected means for controlling the gas exchange of exhaust gases of the internal combustion engine and air entering the engine, the electronic unit 1 for controlling the gas exchange control means, the turbocharger 2, the exhaust gas treatment unit 3 located in the exhaust duct 4 after the turbocharger 2, and two exhaust gas recirculation circuits, primary exhaust gas recirculation circuit 5 and secondary circuit 6 recirculation and exhaust gases communicated with the heat exchanger 7 cooling recirculating gases.

Moreover, the system is equipped with means of regulating gas exchange in the form of at least three multi-position 8, 9 and 10 and two 11 and 12 two-position dampers, two multi-position dampers, the first 8 and second 9 are placed on the exhaust path 4, and the third 10 mainly recirculation channel 16 The inlet 13 of the primary exhaust gas recirculation loop 5 is located after the turbine 14 of the turbocharger 2 and after the exhaust gas treatment unit 3, before the second multiple flap 9, and the outlet 15 of the primary exhaust gas recirculation loop 5 is connected to the main recirculation channel 16 regulating it with the first two-way valve 11, the input 17 of the secondary circuit 6 of the exhaust gas recirculation is located after the turbine 14 of the turbocharger 2 before the first multi-position valve 8 and up to the exhaust gas treatment unit 3,

The interaction and the order of operation of the dampers in the engine exhaust gas recirculation system is as follows.

It should be noted that the operation of all dampers in all modes is governed by the electronic control unit 1 and the dependence of the position of multi-position dampers ensuring optimal exhaust gas for recycling is not a subject of protection in this proposal and is not included in the scope of this application, but is presented as a know-how and subject another application for the method of control and operation of a dual-circuit exhaust gas recirculation system.

A gas engine may have a fourth multi-position damper in the intake path to regulate the incoming air.

On a number of modes, for example, when the engine is not running or when starting the gas engine, both gas recirculation circuits are blocked; for this purpose, the multi-position valve 10, the two-position valves 11 and 12 become closed (see Fig. 1). The first 8 and second 9 multi-position dampers, installed in the system to create enhanced pressure drops for recirculation, are either fully open or the shutter 8 or 9 is positioned in an intermediate position depending on the start conditions (Fig. 1).

In the starting and heating modes of a gas or diesel engine, the first two-position valve 11 is fully closed, and the second two-position valve 12 and the second multi-position valve 9 are fully open. Accordingly, the multi-position dampers of the first 8 and third 10 are in one of the middle positionable positions depending on the conditions of the engine start and warm-up (Fig. 2).

On the modes of small and medium loads at low and medium frequencies of rotation of the gas or diesel engines, a secondary small circuit 6 of gas recirculation operates (Fig. 2). The second two-position valve 12 and the second multi-position valve 9 are fully open, and the first two-position valve 11 is fully closed. The multi-position dampers of the third 10 and first 8 to enhance the recirculation differential are in one of the necessary middle positionable positions. When this recirculating gases with a high content of hydrocarbons in these modes come from the output of the turbine 14 to the input of the compressor 20 through the second two-position valve 12, the main recirculation channel 16, the third multi-position valve 10,

At high loads at high speeds of gas or diesel engines, i.e. At high air flow rates, the first large gas recirculation loop 6 operates (Figure 3). The first two-position valve 11 and the first multi-position valve 8 are fully open, while the second two-position valve 12 is fully closed. The third multi-position damper 10 and the second multi-position 9 are in one of the positioned positions depending on the engine operating conditions. At the same time, completely purified recirculated gases are taken from the inlet 13 of the primary exhaust gas recirculation loop 5 after the exhaust gas treatment unit 3 of the after-treatment system, which prolongs the effective service life of the heat exchanger 7 of the recirculating gas cooling.

The positioning of all dampers is monitored by signals from the position sensors of their electropneumatic actuators and carried out by the electronic control unit 1, depending on the signals from the crankshaft speed sensors of the engine, load, detonation, coolant temperature, air flow, pressure and charge air temperature, which are widely known and usually included in the modern engine equipment, and the drawings are conventionally not shown.

Thus, the creation of a two-circuit exhaust gas recirculation system (EG) of an internal combustion engine with gas turbine supercharging, which contains piping-related means for controlling gas exchange of exhaust gases of the internal combustion engine and air entering the engine, an electronic control unit for means for regulating gas exchange, a turbocharger, an exhaust gas treatment unit located in exhaust manifold after the turbocharger, and two exhaust gas recirculation circuits communicating with the cooling exchanger recirculating their gases, and the system is equipped with means for regulating gas exchange in the form of at least three multi-position and two two-position dampers, two multi-position dampers are located in the exhaust tract, and the third mainly in the recirculation channel, The primary exhaust gas recirculation loop inlet is located after the exhaust gas treatment unit, up to the second multi-position damper, and the primary exhaust gas recirculation loop output is connected to the main recirculation channel with adjustable first dual damper, the secondary exhaust gas recirculation inlet is located downstream of the turbocharger to the first multi-position damper and to the unit exhaust gas treatment, and the output of the secondary circuit recirculation of exhaust gas communicated with the main recirculation channel with the possibility of regulating its second vuhpozitsionnoy damper, wherein the main recirculation channel is connected to the inlet path with the possibility of regulating the third multiposition valve, achieves new technical results described below. and the output of the primary exhaust gas recirculation circuit is in communication with the main recirculation channel with the ability to control the first on-off valve, the input of the secondary exhaust gas recirculation circuit is located after the turbine of the turbocompressor to the first multi-position damper and to the exhaust gas processing unit, and the output of the secondary exhaust gas recirculation circuit is connected to the main recirculation channel with possibility regulation of its second two-way valve, the main recirculation channel is connected to the intake tract with the ability to regulate the third multi-position damper, allows to achieve new technical results described below. and the output of the primary exhaust gas recirculation circuit is in communication with the main recirculation channel with the ability to control the first on-off valve, the input of the secondary exhaust gas recirculation circuit is located after the turbine of the turbocompressor to the first multi-position damper and to the exhaust gas processing unit, and the output of the secondary exhaust gas recirculation circuit is connected to the main recirculation channel with possibility regulation of its second two-way valve, the main recirculation channel is connected to the intake tract with the ability to regulate the third multi-position damper, allows to achieve new technical results described below.

Purchasing dual-EGR (exhaust gas) of the internal combustion engine turbocharged multiposition valve, bred in a primary recirculation channel before on-off valve and after the exhaust gas processing unit main system subsequent exhaust gas processing, and - on-off valve in the other secondary recirculation passage, two multiposition dampers - amplifiers recirculation drops to the required optimal limits in both recirculation circuits after to at each point where recirculating gases are taken, it improves the energy efficiency of the recirculating gases in each of the two recirculation circuits,

As a result of this improvement, the efficiency of the dual-circuit exhaust gas recirculation system (EG) of an internal combustion engine with gas turbine supercharging, its compactness, durability of the heat exchanger of recirculating gases cooling is reduced, emissions of nitrogen oxides and suspended hydrocarbon particles into the atmosphere are reduced and the fuel efficiency of the engine is improved.

When the engine is not running or the gas engine is starting up and at idle speeds, both gas recirculation circuits are blocked, all dampers are closed.

At low and medium loads at low and medium frequencies of rotation of the gas and diesel engines, a second small gas recirculation circuit with recirculating gases to the exhaust gas treatment unit is operating. Recirculating gases in these modes at elevated, relative to the primary circuit, recirculation drops come from the turbine outlet and then through the second small gas recirculation loop to the compressor inlet. Increased pressure drops of the recirculation gases are achieved by the corresponding intermediate position of the multi-position dampers, which is set using a signal from the electronic control unit.

At high loads and at high speeds of diesel and gas engines, i.e. at high air flow rates, the first, large gas recirculation circuit works, which allows to supply a sufficient volume of recirculation gases with high efficiency with a high flow rate of the fuel-air mixture. In addition, completely purified recirculating gases are extracted from the output of the exhaust gas treatment unit of the exhaust gas aftertreatment system, which carry the pollution accumulated in the heat exchanger of the recirculating gases, which makes it possible to achieve an additional technical result that extends the service life and efficient the work of the common for the two circuits of the heat exchanger cooling recirculating gases,