RU2786859C1 - Method and experimental system with independent supply air source for two-stroke ice - Google Patents

Abstract

FIELD: engine building.

SUBSTANCE: inventions group relates to engine building. A method with an independent source of charge air for a two-stroke internal combustion engine with a direct-flow valve gas exchange system, wherein an independent source of charge air is formed from a starting air cylinder with a volume of 5 m³ filled with atmospheric air at a pressure of 30 bar. Charge air is supplied at a constant pressure of 3.1 bar at all engine loads through the pressure reducing valve to the air receiver and from it to the cylinders. The processes of filling cylinders with air, compression, fuel supply, formation of a fuel mixture, its further ignition and expansion, as well as the release of gases are disclosed, the exhaust gases leaving the cylinders when the exhaust organs of each cylinder are opened are sent to the exhaust manifold and from it through the flow path of the turbine GTN with dismantled rotor and nozzle apparatus into the utilization boiler or into the atmosphere. Also disclosed is an experimental system with an independent source of charge air of a two-stroke internal combustion engine.

EFFECT: increasing the indicator efficiency by increasing the boost pressure in the engine.

2 cl, 3 dwg

Description

FIELD OF TECHNOLOGY

SUBSTANCE: group of inventions relates to diesel internal combustion engines, both two-stroke and four-stroke, both marine and coastal, used in coastal power plants, in particular, to means of supplying charge air, and can be used when conducting experiments on the introduction of technologies to increase indicator Efficiency based on the modernization of engine boost, reducing fuel consumption and improving the environmental parameters of exhaust gases.

BACKGROUND OF THE INVENTION

The indicator efficiency of the engine is directly related to the energy of the supplied heat and useful work per unit of time, i.e. with fuel quality, characterized by the net calorific value, the amount of fuel supplied to the cylinders per unit of time and the indicator power.

An increase in the indicated power of engines is achieved by adjusting the quantities that affect it. The indicator power N _IND of the internal combustion engine is determined by the expression N _IND - k⋅P _MI ⋅n⋅i, where P _MI is the average indicator pressure (kg/cm ² ); n - engine speed (rpm); i - number of engine cylinders; k=1.745⋅D ² ⋅S⋅m - cylinder constant determined by cylinder diameter - D, piston stroke - S and engine cycle - m.

Traditionally, to increase the indicated power of engines, ICE manufacturers are developing in areas related to the optimization of the parameters that determine the indicated power. These areas are:

a) Increasing power by increasing the cylinder diameter - D. The method was used for about 50 years, which led to the largest diameter of 90 cm for MAN-B&W and SULZER engines and to an increase in engine weight. A further increase in the cylinder diameter would be unprofitable.

b) Increasing power by increasing the piston stroke - S. The method has been used for about 40 years, which led to the creation of long- and super-long-stroke models of the LMC and SMC type (S / D> 3÷4 ratio, respectively) of MAN-B&W and SULZER engines, and also to increase the mass of the engine. A further increase in the piston stroke was unprofitable.

c) Increasing power by increasing the speed - n. The method is not applicable for low-speed and medium-speed engines.

d) Increasing power by increasing the number of cylinders - i. The method was used up to a certain point, and also leads to an increase in the mass of the engine. Further increase in the number of cylinders is unprofitable.

e) Increasing efficiency (indicator efficiency - η _IND ) by forcing the engine to boost. The method has been used for about 40 years, resulting in an increase in boost pressure from 1 bar to 2.9 bar. A further increase in boost pressure was not possible due to the need to increase the structural super strength of the metal of the components and parts of the core, cylinder liner, cylinder covers, parts and components of the translational and rotational movement of the engine. Because with an increase in charge air pressure by 1 bar, the compression pressure and combustion pressure will increase by 38 ÷ 40 bar, for which all the parts and assemblies listed earlier are not ready for their strength characteristics.

It follows that when designing diesel engines, the parameters that determine the power of a diesel engine cannot be chosen arbitrarily, rather complex coordination of their values with each other is required, depending on the purpose of the diesel engine. [1] Voznitsky I.V., Punda A.S. "Marine internal combustion engines", volume 2, p. 54. - MORKNIGA, M. 2008

A special place among these parameters is occupied by the value of the average indicator pressure P _MI , which depends on the level of boosting the diesel engine by boost. An increase in the degree of boost at a constant average indicator pressure leads to a decrease in the duration of fuel combustion in the cylinder - an increase in the speed and intensity of combustion, a decrease in the duration of fuel injection into the cylinder and, as a result, to fuel consumption, [2] Fomin Yu.Ya. Marine diesels. Fuel supply in marine diesel engines”, pp. 15-19.-V/O “Mortekhinformreklama”, M. 1988. However, the implementation of these technical measures leads to the complication of the design and operation of pressurization systems.

The following patent documents characterizing the prior art are known.

Known "System for cooling fresh charge and exhaust gases of a marine diesel engine supplied to the intake" according to the patent of the Russian Federation No. 108107 for a utility model, IPC F02G 5/00. Published September 10, 2011, Bull. No. 25. The purpose of this system is to cool the fresh charge of charge air and exhaust gases supplied to the intake. Exhaust gas cooling can increase ignition delay, reduce heat generation and significantly reduce NOx emissions. Efficient cooling of a fresh charge of charge air solves not only the problem of increasing the amount of air entering the cylinders, but also the task of reducing the operating cycle temperatures and thermal loads of the diesel engine when boosting it. Thus, the proposed utility model allows you to maintain optimal operating parameters of the systems in all operating modes of the diesel engine and will contribute to obtaining a significant economic effect and the formation of integrated automation systems for water transport ships.

In the development of this system, a “System for cooling a fresh charge and exhaust gases of a marine diesel engine supplied to the intake” was proposed according to the patent of the Russian Federation No. 2466289 for the invention, IPC F02G 5/02, F02B 29/04, F02M 25/07. Published November 10, 2012, Bull. No. 31. The system for cooling a fresh charge of charge air and exhaust gases of a marine diesel engine supplied to the inlet contains: exhaust, suction and recirculation pipelines, a waste boiler, a control unit, temperature and load sensors, elements for supplying and controlling heat carriers and coolants, heat exchangers for exhaust gases and fresh air charge. The exhaust gas heat exchanger is installed on the recirculation pipe. The fresh charge heat exchanger is installed on the suction pipe. The exhaust gas and fresh charge heat exchangers can be connected to an absorption chiller. The refrigerant can be supplied to the heat exchangers through electronic three-way valves, depending on the load of the diesel engine. The technical result consists in increasing the amount of air entering the cylinders, and in reducing the temperatures of the working cycle and the thermal loads of the diesel engine when it is boosted by supercharging.

Known "Method of operation of a marine low-speed diesel engine and the device of the combustion chamber for its implementation" according to the patent of the Russian Federation No. 2256806 for the invention, IPC F02B 3/02. Published July 20, 2005

This technical solution relates to marine low-speed two-stroke diesel engines with a direct-flow-valve gas exchange scheme and was developed in order to increase the indicator efficiency of a diesel engine and reduce fuel consumption. The invention provides an increase in the indicator work of gases per cycle by reducing the angle of the beginning of the opening and, accordingly, the end of the closing of the exhaust valve (counting the angles relative to the bottom dead center), improving the quality of mixture formation by changing the shape of the combustion chamber. Fuel injection is carried out in the direction perpendicular to the axis of the cylinder, and the spray jets are directed towards each other with a length not exceeding the radius of the cylinder sleeve. With an increased diameter of the exhaust valve (flow area), the exhaust gas release begins later at a smaller angle of rotation of the crankshaft relative to the bottom dead center. The device of the combustion chamber contains a semi-cap type cylinder cover with an exhaust valve in the center, a piston, the bottom of which is made flat, two nozzles for fuel injection are located on diametrically opposite sides of the cylindrical part of the cylinder cover perpendicular to the axis.

CRITIQUE OF ANALOGUES

The described patents are aimed at increasing the indicator efficiency, however, in the first case, the use of cooled exhaust gases in the combustion process, on the contrary, leads to a decrease in the amount of fresh air charge, an integral component of combustion, to an increase in the duration of combustion (decrease in the combustion rate), and hence to an increase in the temperature of the exhaust gases. gases in the final result, i.e. to an increase in heat losses with exhaust gases and, as a result, to an increase in fuel consumption, i.e. to an increase in the input energy with the same useful work of the piston. All these factors, on the contrary, reduce the indicator efficiency. Moreover, it is very doubtful that in this case the concentration of nitrogen oxides harmful to the atmosphere NOx will decrease. In the second case, the constructive solution does not allow to solve this problem effectively enough.

As a prototype, a traditional gas turbine pressurization system at a constant gas pressure in front of the turbine was adopted. The system includes a gas turbine, compressor, cylinders, exhaust manifold, air receiver, air cooler. Combustion products from all cylinders are sent to one common exhaust manifold, from where gases enter one or two turbines. This system does not provide the highest possible indicator efficiency, because there is no technical possibility to increase the boost pressure more than 2.9 bar. With a further increase in boost pressure, the components and parts of the core, cylinder liner, cylinder covers, parts and components of the translational and rotational motion of the engine do not withstand due to their strength characteristics, because when the charge air pressure is increased by 1 bar, the compression and combustion pressures increase by 38÷40 bar. The fuel supply advance angle is 10÷12° before TDC, which also does not provide optimal mixing of fuel and fresh air charge. A further increase in the advance angle of the fuel supply is also not possible for the same reasons of the strength characteristics of parts and assemblies of the core, cylinder liner, cylinder covers, parts and assemblies of the translational and rotational motion of the engine, because its increase by 1° to TDC leads to an increase in the maximum combustion pressure by 3 bar.

[3] Voznitsky I.V., Punda A.S. Marine internal combustion engines. Theory and operation of engines. Volume. 2, pp. 166÷167. -MORKNIGA, M. 2008

TECHNICAL PROBLEM

The technical objective of the proposed group of inventions is to increase the efficiency of both two-stroke and four-stroke internal combustion engines, reduce fuel consumption, reduce harmful emissions into the atmosphere through the use of an independent source of charge air.

To achieve the stated technical task, a method is proposed with an independent source of charge air for a two-stroke engine with a direct-flow valve gas exchange scheme, including charge air supply, fuel injection, mixture formation, combustion, engine piston stroke from top dead center (TDC) to bottom dead center (BDC). ), the exhaust gas outlet, characterized in that an independent source of charge air is formed from a stationary starting air cylinder with a volume of 5 m ³ located in the engine room (MO), compressed to a pressure of 30 bar and air is supplied as charge air with a constant pressure of 3.1 bar at all engine loads through the pressure reducing valve into the air receiver and from it into the under-piston spaces of the cylinders, while when the piston is at BDC, the charge air displaces the residual exhaust gases that exit through the open exhaust valve and fills the cylinder through the purge windows of the sleeve, when the piston moves from NM T to TDC, first close the purge windows when it is in the position of 140.5 ° to TDC, then when it reaches its position of 102.4 ° to TDC, the exhaust valve begins to compress a fresh charge of air and, when the piston is at TDC, they reach a compression pressure equal to combustion pressure value of 140.2 bar at 100% load of the standard boost system, then at the same moment fuel is supplied to the cylinder through the nozzle from the high pressure fuel pump, and the fuel supply advance angle is preliminarily adjusted to a value equal to 0 ° before TDC, the fuel is mixed with a fresh compressed charge of air until a fuel mixture is formed; when the piston moves from TDC to BDC on the expansion line 12.5° after TDC, the fuel mixture is ignited and thermal energy is supplied for the piston stroke from 12.5° after TDC to the opening of the exhaust valve when the piston position reaches 102.4° after TDC, and the exhaust gases leaving the cylinders when the exhaust organs of each cylinder are opened are sent to the exhaust manifold and from it through the flow path of the GTN turbine with the dismantled rotor and nozzle apparatus into the utilization boiler or into the atmosphere.

To achieve the stated technical task, an experimental system with an independent source of charge air for two-stroke internal combustion engines is also proposed, containing an engine exhaust manifold connected to the exhaust manifolds of each cylinder having purge and exhaust ports for internal combustion engines with a loop gas exchange system or purge ports and an exhaust valve for internal combustion engines with direct-flow-valve gas exchange system, a gas turbocharger - GTN, outside air taken from the MO through the air filter and compressed in the compressor part of the GTN, an air cooler of the GTN, an auxiliary blower and an air receiver of the engine, characterized in that it is equipped with a charge air supply module, including one located in the engine compartment (MO) starting air cylinder with a pressure of 30 bar, a pressure reducing valve to create the necessary increased constant boost pressure, a steel plug 10 mm thick with sealing material (high-temperature paronite gasket 3 mm thick or high-temperature silicone sealant) between the flow parts of the turbine and the turbocharger compressor after dismantling the turbocharger rotor and the nozzle apparatus, the cap of the turbocharger flow path, the cap from the turbocharger compressor to the air cooler, moreover, charge air of constant pressure at all engine loads comes from a starting air cylinder with a volume of 5 m ³ through the pressure reducing valve into the air receiver and out of it into the under-piston spaces of the cylinders, the GTN remains in the system, but with the dismantled rotor and nozzle apparatus for the unhindered release of exhaust gases.

TECHNICAL RESULT

The technical result consists in increasing the indicator efficiency by increasing the boost pressure in the engine. In the proposed method and system, the engine is boosted by boost by increasing the boost pressure to 3.1 bar, in contrast to the standard pressure of 2 bar at a given load of 87% MEM, and by changing the fuel supply advance angle to 0° to TDC, in contrast to standard fuel feed advance angle of 12.5° to TDC, i.e. it becomes technically possible to supply fuel at the moment when ignition occurs at 12 ÷ 13 ° after TDC.

SUMMARY OF THE INVENTION

The essence of the proposed group of inventions is as follows. It is proposed to use an independent source of charge air - without the use of turbines (as an experimental system). The starting air cylinder in all engines, both marine and coastal, used in coastal power plants, is designed to start the internal combustion engine. In the proposed solution, it is also used for pressurization during the operation of the internal combustion engine. The use of air from a pressurization cylinder without the participation of a gas turbine pump is fundamentally new for increasing the boost pressure in an experimental system, since already installed gas turbine pumps are not provided with sufficiently effective pressurization.

An independent source of charge air includes a cylinder of starting air compressed to 30 bar. This makes it possible to supply an increased constant charge air pressure of 3.1 bar, in contrast to the standard 2 bar, without the use of a turbocharger from the starting air cylinder through a pressure reducing valve, in addition, a modified fuel feed advance angle to a value equal to 0° before TDC ensures efficient mixing fuel with charge air and efficient combustion with a higher speed and intensity of heat transfer, while it is possible to reduce the duration of injection and combustion of fuel in the cylinder (reduce cyclic supply or fuel consumption).

Conditions for improving mixture formation are created, the completeness of fuel combustion increases, the exhaust gas temperature and fuel consumption decrease, both of which lead to a decrease in SOx, CO ₂ , COx and NOx emissions into the atmosphere.

The possibility of using an independent source of inflatable air is achieved by the combination of all the features of the claims.

The pressure reducing valve allows the supply of charge air at a constant pressure of 3.1 bar as opposed to 2 bar.

The implementation of the ignition of the fuel mixture and the supply of thermal energy for the piston stroke on the expansion line from 12.5 ° after TDC to the opening of the exhaust valve when the piston reaches 102.4 ° after TDC provides the best conditions for burning the fuel mixture - the fuel burns out almost completely, time combustion is minimal.

The use of plugs in the system ensures the tightness of the system after dismantling the turbine rotor and nozzle apparatus.

GRAPHIC MATERIALS

The essence of the invention is illustrated by graphic materials, which show: in Fig. 1 is a schematic diagram of the method; in fig. 2 - schematic diagram of the system; in fig. 3 - (a) - standard working indicator diagram, (b) - indicator diagram of the experimental system.

In FIG. 1 and 2 are shown:

1 - cylinder sleeve;

1a - outlet windows of the cylinder sleeve of a two-stroke internal combustion engine with a loop gas exchange system; 1b - exhaust valve of a two-stroke internal combustion engine with a direct-flow valve gas exchange system;

1c - purge windows of the cylinder sleeve;

2 - air receiver of the engine;

3 - air cooler GTN;

4 - a plug between the flow parts of the turbine and the GTN compressor;

5 - air filter GTN;

6 - auxiliary blower;

7 - plug of the flow part of the GTN turbine;

8 - exhaust manifold of the engine;

9 - plug from the GTN compressor to the air cooler;

10 - starting air cylinder;

11 - pressure reducing valve.

OPERATION OF THE METHOD AND SYSTEM

The method and system work as follows. Charge air of constant pressure of 3.1 bar at all engine loads comes from the starting air cylinder 10 with a volume of 5 m ³ through the pressure reducing valve 11 into the air receiver 2 and from it into the under-piston spaces of the cylinders 1; when the piston is at BDC, the charge air displaces the residual exhaust gases that exit through exhaust valves 1b (for internal combustion engines with a direct-flow valve gas exchange system) and fills cylinder 1 through purge windows 1c of the cylinder bushing 1. When the piston moves from BDC to TDC, first with the same the piston closes the purge windows 1c when its position reaches 140.5 ° to TDC, then when its position reaches 102.4 ° to TDC, the exhaust valve 1b closes using a mechanical-hydraulic camshaft system (for internal combustion engines with a direct-flow valve gas exchange system), fresh the air charge begins to compress and, when the piston is at TDC, reaches a compression pressure equal to the combustion pressure value of 140.2 bar at 100% load of the standard boost system, then at this moment fuel is supplied to the cylinder through the nozzle from the high pressure fuel pump with an already changed advance angle fuel supply from 12.5° to TDC of the standard turbo system to 0° to TDC, mixed with fresh compressed charge of air and forms a fuel mixture. When the piston moves from TDC to BDC on the expansion line 12.5° after TDC, the fuel mixture is ignited with the supply of thermal energy to carry out the piston stroke from 12.5° after TDC to the opening of the exhaust valve when the piston reaches 102.4° after TDC (for internal combustion engines with direct-flow-valve gas exchange system). Exhaust gases exiting cylinders 1 when the exhaust organs of each cylinder are opened enter the exhaust manifold and from it through the flow path of the GTN turbine (with the rotor and nozzle apparatus dismantled) into the utilization boiler or into the atmosphere.

The operation of the HYUNDAI MAN-B&W 6S50MC marine engine (MEM 11640 hp at 127 rpm) was tested on the test bench during its forcing through the charge air. An external source - a cylinder of starting air through a pressure reducing valve, created a constant boost pressure, and adjusted the advance angle of the fuel supply. The indicator diagram showed a constant average indicator pressure with reduced fuel consumption, and, consequently, an increase in indicator efficiency. The test results are shown in the table.

On the indicator diagrams (Fig. 3(a) and (b)) the dashed line indicates their collapsed form, according to which the areas of the diagrams are determined, and the average indicator pressures of the cycles are determined from the area. On the abscissa axis there is a scale of crankshaft rotation angles from "-180°" to "180°". On the ordinate axis there is a pressure scale of the working fluid (air and working gases) in the cylinder from "0 bar" to "150 bar". The compression stroke occurs from BDC (bottom dead center, corresponding to "-180 °" pkv) to TDC (top dead center - TDC - top dead center, corresponding to "0 °" pkv), and the ignition and expansion strokes from TDC (top dead center - TDC - top dead center, corresponding to "0°" pkv) to BDC (bottom dead center, corresponding to "180°" pkv). In the piston position at TDC (top dead center - TDC - top dead center, corresponding to "0 °" pkv), the compression pressure corresponds to the value of 103.62 bar of the standard boost system (Fig. 3(a)) and 140.2 bar of the experimental boost system (Fig. 3(b)). At a piston position of ≈20° after TDC, the combustion pressure corresponds to 121.4 bar of the standard boost system (FIG. 3(a)) and 140.2 bar of the test boost system (FIG. 3(b)).

The areas of both indicator diagrams, and hence the average indicator pressures, are the same. However, fuel consumption differs by 1.91 times in favor of the experimental system.

The proposed group of inventions is aimed at increasing the efficiency of both two-stroke and four-stroke internal combustion engines, saving hydrocarbon resources, reducing harmful emissions of NOx, SOx, CO and CO ₂ with exhaust gases into the atmosphere.

Claims (2)

1. A method with an independent source of charge air for a two-stroke internal combustion engine with a direct-flow valve gas exchange system, including the supply of charge air, fuel injection, mixture formation, combustion, engine piston stroke from top dead center (TDC) to bottom dead center (BDC), exhaust gases, characterized in that an independent source of charge air is formed from a starting air cylinder with a volume of 5 m ³ located in the engine room (MO), filled with atmospheric air at a pressure of 30 bar, charge air is supplied with a constant boost pressure of 3.1 bar at all engine loads through the pressure reducing valve into the air receiver and from it into the under-piston spaces of the cylinders, while when the cylinder piston is at BDC, the charge air displaces the residual exhaust gases that exit through the open exhaust valve and fill the cylinder through the purge windows of the sleeve, when the piston moves from BDC to TDC first close the purge ok on when it is in the position of 140.5 ° to TDC, then when it reaches its position of 102.4 ° to TDC, the exhaust valve begins to compress a fresh charge of air and, when the piston is at TDC, a compression pressure equal to the value of the combustion pressure of 140.2 bar is reached at 100% load of the pressurization system, then at the same moment fuel is supplied to the cylinder through the nozzle from the high-pressure fuel pump, and the advance angle of the fuel supply is preliminarily adjusted to a value equal to 0 ° to TDC, the fuel is mixed with a fresh compressed air charge until a fuel mixtures; when the piston moves from TDC to BDC on the expansion line 12.5° after TDC, the fuel mixture is ignited and thermal energy is supplied for the piston stroke from 12.5° after TDC to the opening of the exhaust valve when the piston position reaches 102.4° after TDC, and the exhaust gases leaving the cylinders when the exhaust organs of each cylinder are opened are sent to the exhaust manifold and from it through the flow path of the turbine of the gas turbocharger (GPU) with the rotor and nozzle dismantled into the utilization boiler or into the atmosphere. 2. An experimental system with an independent source of charge air for a two-stroke internal combustion engine, containing an engine exhaust gas manifold connected to the exhaust manifolds of each cylinder having purge and exhaust ports for an internal combustion engine with a loop gas exchange system or purge ports and an exhaust valve for an internal combustion engine with a direct-flow valve gas exchange system , a gas turbocharger (GPU), outside air taken from the MO through an air filter and compressed in the compressor part of the GTN, an air cooler of the GTN, an auxiliary blower and an engine air receiver, characterized in that it is equipped with a charge air supply module, including one located in the engine room (MO) starting air cylinder with a pressure of 30 bar, a pressure reducing valve for creating the necessary increased constant boost pressure, a 10 mm thick steel plug with sealing material between the turbine and GTN compressor flow parts after dismantling the GTN rotor and nozzle apparatus, a flow hour plug ty GTN, a plug from the GTN compressor to the air cooler, and charge air of constant pressure at all engine loads comes from a starting air cylinder with a volume of ⁵ m rotor and nozzle apparatus for the unimpeded release of exhaust gases.

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