DK178133B1 - Large turbocharged diesel engine with energy recovery device - Google Patents

Abstract

Large turbocharged diesel engine, equipped with exhaust gas boilers and a power turbine for energy recovery in the exhaust gases. One of the boilers may be an integral part of the exhaust gas receivers. Part of the exhaust gas flow before the turbocharger turbine seen in the direction of the flow is branched to the power turbine. The engine contains a preheater boiler at the low pressure side of the turbocharger turbine, while a superheat boiler is located at the high pressure side of the turbocharger turbine. The engine can be operated with highly humidified rinsing air in order to increase the amount of energy in the recoverable exhaust gases. The engine can also be operated as a heat pump, the exhaust gas leaving the engine having a temperature lower than the ambient temperature.

Description

LARGE TURBOLED DIESEL ENGINE WITH ENERGY RECOVERY EQUIPMENT

FIELD OF THE INVENTION

The present invention relates to a large turbocharged diesel engine with one or more boilers heated with exhaust gas, and more particularly to a large turbocharged diesel engine equipped with an exhaust turbine powered by exhaust gas which branches before the turbocharger turbine in the direction of flow.

BACKGROUND OF THE INVENTION

EP 0 434 419 presents a large turbocharged two-stroke diesel engine in which heat energy from the exhaust gas is recovered by a combination of a boiler on the low-pressure side of the turbocharger and a boiler on the high-pressure side of the turbocharger. At lower engine loads, the recovery of the heat energy from the exhaust gases before being directed to the turbocharger is reduced by passing a portion of the exhaust gas directly into the turbocharger, bypassing the first boiler in the direction of flow. However, when a boiler is placed between the exhaust gas receiver and the turbine in the turbocharger, the overall design becomes relatively bulky and complicated. In addition, the increased length of flow path between the exhaust valves and the turbocharger reduces the reaction of the turbocharger in connection with accelerations. Furthermore, this engine only regains heat while no precautions have been taken to convert the recovered energy into a more usable form of energy such as rotational power or electricity.

PRESENTING THE INVENTION

In the light of the foregoing, the object of the present invention is to provide a turbocharged diesel engine of the type mentioned earlier which is more compact and less complicated to construct. This object is achieved according to claim 1 by providing a turbocharged diesel engine of the said type, containing a plurality of cylinders, each connected to an exhaust gas receiver via their respective manifold pipes, a first exhaust gas pipe seen in the direction of flow to direct the exhaust gases from the exhaust gas receiver. to the turbine inlet of the turbocharger, another exhaust gas tube seen in the direction of flow to direct the exhaust gases from the outlet of the turbine of the turbocharger into the atmosphere, one or more boilers heated with the exhaust gas, or heat exchangers to recover the heat energy from the exhaust gases; at least one of these boilers or heat exchangers is located within said exhaust gas receiver.

By physically placing one of the boilers within the exhaust gas receiver, there is effectively a smaller component in the system that requires space in the narrow area at the top of a large turbocharged diesel engine. Thus, this measure creates more space around the engine and also reduces the extent of the pipeline system. In addition, a boiler housing is dispensed with, as the exhaust gas receiver housing now fulfills two functions: providing a cavity for receiving and assembling the exhaust gases from individual cylinders and providing a cavity for placing a boiler. A further advantage is that the pressure drop through the boiler has the opportunity to be three times greater than in the traditional designs without a reduction in engine performance. An increased pressure drop, in turn, enables an increased gas velocity, which enables a significant reduction of the heat exchanger surface (when all other parameters are the same), thus resulting in a much smaller boiler.

The large turbocharged diesel engine can additionally contain a preheater / evaporator boiler on the low pressure side of the turbocharger. In this case, the boiler located within the exhaust gas receiver is used to superheat steam produced by the boiler on the low pressure side of the turbocharger. In this connection, the quality of the steam is improved, especially when the superheated steam is to be used in a steam turbine.

The large turbocharged diesel engine may additionally contain a steam turbine powered by steam produced by the boiler or boilers. In this connection, the energy to be recovered from the exhaust gases is converted into a more usable form of energy. The power turbine can operate an electric generator which serves to convert the rotary power to electricity.

The exhaust gas receiver may contain a plurality of boilers or several stages within a single boiler. The energy of the exhaust gas can thus be more efficiently transferred to the steam.

The plurality of boilers may constitute a multi-stage superheated steam system which contains preheat / evaporator boilers and superheat / evaporator boilers.

Further objects, features, advantages and characteristics of the charged internal combustion engine according to the invention will be apparent from the detailed description.

BRIEF DESCRIPTION OF THE INVENTION

In the following detailed part of the present description, the invention is explained in more detail with reference to the exemplary embodiments shown in the drawings, in which: Figure 1 shows a partial side view of a large turbocharged diesel engine according to a first embodiment of the invention; Figure 2 is a longitudinal cross-section through the engine of Figure 1; Figure 3 is a schematic diagram of a large turbocharged diesel engine with heat energy recovery measures according to another embodiment of the invention; Figure 3a is a diagram showing the operating parameters of the engine of Figure 3; a large turbocharged diesel engine with heat energy recovery measures according to a third embodiment of the invention; Figure 4a is a diagram showing the operating parameters of the engine of Figure 4; Figure 5 schematically shows a large turbocharged diesel engine with heat energy recovery measures according to a third embodiment.Figure 5a is a diagram showing the operating parameters of the motor of Figure 5; Figure 6 shows another embodiment of the invention in which the motor is operated as a heat pump; Figure 7 shows a further embodiment of the invention which does not use a turbocharger, but instead provided with a turbine and fan connected electrically to each other, and Figure 8 shows another embodiment of the invention using exhaust gas recirculation.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the following detailed description, the large turbocharged diesel engine according to the invention is described in the form of a large two-stroke diesel engine by means of the preferred embodiments.

The design and operation of large turbocharged diesel engines such as large crosshead type two-stroke diesel engines are well known in themselves and should not require further explanation in the present context. Further details relating to the operation of the charging and exhaust gas systems are given below.

Figure 1 shows a first embodiment of a top region of a large two-stroke diesel engine 1 according to the invention. This engine is provided with a plurality of cylinders arranged side by side in a row. Each cylinder is provided with an exhaust valve (not shown) connected to its cylinder cover. The exhaust ducts can be opened and closed by means of the exhaust valve. Manifold pipes connect the respective exhaust ducts with an exhaust gas receiver 3. The exhaust gas receiver 3 is located parallel to the row of cylinders. The manifold tubes 40 open into the exhaust gas receiver 3, and an exhaust pipe leads from the exhaust gas receiver to the turbine in a turbocharger. In engines with a very large number of cylinders (for example, 10 or more cylinders) the exhaust gas receiver can be split longitudinally into two or more parts (not shown).

In this embodiment, the exhaust gas receiver 3 has a cylindrical housing 42 which, as shown in FIG. 2, is provided at its ends with removable covers 44. The cylindrical housing 42 contains a heat exchanger 23 through which the exhaust gases can flow to produce superheated steam. Thus, the heat exchanger 23 acts as a boiler. In addition, the cylindrical housing 42 contains a manifold 46 into which the manifold tubes 40 release the exhaust gases.

As shown in FIG. 2, the cylindrical housing 42 for the exhaust gas receiver is divided into two heat exchanger portions 50a and 50b and collector conduit portions 46a and 46b, juxtaposed with a central outlet chamber 52 which exits the exhaust gases via an exhaust pipe. Accordingly, the construction of the exhaust gas receiver 3 is symmetrical with respect to its central radial plane.

Both sections 50a, 50b of the heat exchanger arrangement consist of several successive heat exchange elements which are well known in themselves and which are separated by spacers 49. Each section 50a, 50b contains two heat exchange elements 57a, 58a, 57b, 58b, each of which in particular, a large number of tubes extending in the direction of gas flow indicated by an arrow drawn as a fully drawn line, parallel to the longitudinal axis of the cylindrical housing. The flow directions in the respective heat exchanger portions 50a and 50b are opposite each other and point towards each other.

The cross-sectional contour of the eccentrically placed heat exchanger elements 57a, 58a, 57b, 58b is in the form of a ring segment adjacent to the inner circumference of the cylindrical housing 42. The ring segments can be divided into sub-segments to facilitate mounting (not shown).

The cylindrical housing 42 for the exhaust gas receiver 3 is provided with a partition 63 separating the heat exchanger elements from the rest of the cross-section of the interior of the exhaust gas receiver 3, and in this connection the cross-section of the interior of the exhaust gas receiver divides into a channel for receiving the heat exchanger elements and collecting and passing the exhaust gases toward the duct with the heat exchanger elements 57a, 58a, 57b, 58b.

In the latter channel (which the manifold pipes 40 open into) the exhaust gas is directed in the direction of the arrow, shown in broken lines.

The heaters can be retracted into the duct to receive the heaters. The longitudinal exterior heating elements are separated from the interior heating elements by spacers 49. The assembled unit is held in place by locking plates 66.

The collecting ducts 46a, 46b have a funnel-shaped cross-sectional shape which opens in a radially outward direction. The manifold tubes 40 are positioned so as to blow the exhaust gases into the respective collecting ducts 46a, 46b.

The connecting ducts 46a, 46b are separated from the central outlet chamber 52 by means of side walls 69 which are connected to the frontal ends of the connecting ducts. The collecting ducts 46a, 46b are open at their opposite ends at some distance from the removable covers 44. In this connection, counterflow chambers 71a, 71b are formed in the region at the ends of the exhaust gas receiver housing 42. The counterflow chambers 71a, 71b connect the conduits 46a, 46b , in which the heat exchanger sections are recorded. Thus, flow paths are formed on both sides of the outlet chamber 52 connecting the take-up channels 46a, 46b through the channels containing the heat exchanger elements with the outlet chamber. The exhaust gases leaving the manifold tubes 40 in the respective collecting ducts 46a, 46b flow, as shown in FIG. 2, with the arrows plotted in dotted lines, to the counterflow chambers 71a, 71b and from them, as shown in FIG. the arrows drawn in solid lines through the respective heat exchanger elements 57a, 58a, 57b, 58b toward the outlet chamber 52.

Thus, the housing 42 of the exhaust gas receiver 3 serves to contain both an exhaust gas cavity and a boiler for recovering heat energy from the exhaust gases. By integrating the boiler inside the exhaust gas receiver, the space needed for an exhaust boiler can be saved and the housing of an exhaust gas boiler can be waived.

Figure 3 shows another embodiment of a large cross-head type turbocharged two-stroke diesel engine 1 with its intake and exhaust systems. The engine 1 contains a charge air receiver 2 and an exhaust gas receiver 3. The exhaust gas receiver 3 may be of the type described in the first embodiment, but this is not necessarily the case. The engine is equipped with exhaust valves (one or more for each cylinder) not shown. The motor 1 can e.g. is used as a main engine in a seagoing vessel or as a stationary engine for operating a generator in a power plant. For example, the overall power output of the engine can range from 5,000 to 110,000 kW, but the invention can also be used in four-stroke diesel engines with a power of, for example, 1,000 kW.

The charging air flows from the charging air receiver 2 to the rinsing air openings (not shown) on the respective cylinders. When the exhaust valve 4 is opened, the exhaust gas flows through manifold tubes and into the exhaust receiver 3 and thence through a first exhaust pipe 5 to a turbine 6 of a turbocharger, from which the exhaust gas flows through a second exhaust pipe 7. By means of a shaft 8, the turbine 6 a compressor 9 supplied via an air inlet 10. Compressor 9 supplies charged air under pressure to a charge air line 11 which leads to the charge air receiver 2.

The suction air in conduit 11 passes through an intermediate cooler 12 to cool the rinsing air - leaving compressor 9 at a temperature of about 200 ° C - to a temperature of about 36 ° C.

The cooled flushing air is fed through an auxiliary fan 16 driven by an electric motor 17 which pressurizes the flushing air flow (often only under low or partial load conditions) and to the flushing receiver 2. At higher loads, the amount of flushing air supplied by the the turbocharger compressor 9 is sufficient to operate the engine and the auxiliary fan 16 is stopped. In this mode, the auxiliary fan 16 is bypassed by the wire 15.

A first boiler 23, preferably in the form of a heat exchanger e.g. of the pipe or fins type, is placed in the first exhaust line 5, ie. prior to turbine 6 viewed in the direction of flow, and uses heat energy in the exhaust gases to produce steam. The exhaust gases, when they arrive at the exhaust gas receiver 3, have a temperature of about 455 ° C and the temperature at the entrance to the first boiler 23 is only slightly lower. The first boiler 23 may be an integral part of the exhaust gas receiver 3, as shown and explained with reference to the first embodiment above.

Following the boiler 23 in the direction of the flow, the exhaust line is branched off, the greater part of the exhaust gases continuing via the exhaust pipe 5 towards the turbine 6, and a smaller part of the exhaust gases flowing through a line 30 towards a power turbine 31. The additional power turbine 31 drives an electric generator 32.

Thus, an excess energy in the exhaust gas stream is converted into electrical energy, ie. energy with a high exergy. The amount of exhaust gas which branches to the power turbine 31 can be controlled via a variable flow controller (not shown) in line 30. The exhaust gases exiting the power turbine 31 are directed to another exhaust line 7 and fed back to the main gas flow.

The second exhaust conduit 7 directs the exhaust gases to the inlet of another boiler 20 containing a heat exchanger, e.g. of the pipe or fins type. A third exhaust line 21 conducts charging air from the outlet of the second boiler 20 into the atmosphere. Before the exhaust gases reach the atmosphere, they can be purified in an SCR reactor (not shown) to reduce e.g. NOx levels and pass through a silencer (not shown) to reduce noise pollution.

The second boiler 20 uses the heat in the exhaust gas stream to produce steam under pressure. At this point, the exhaust gas temperature is lower than when it exits the cylinders, typically the temperature at the outlet of the turbocharger turbine 6 is in the range between 250 and 300 ° C.

A conduit 22 conducts the steam produced in the second boiler 20 to the inlet of the first boiler 23. The first boiler is heated with exhaust gases having a temperature of about 450 ° C, thus being a very effective medium for evaporating. / overheat the water / steam entering the first boiler 23.

The superheated steam is passed via line 34 to a steam turbine 37 which converts the energy of the steam into rotary mechanical power. The steam turbine 37 drives an electric generator 35 to produce electrical energy that can be used aboard a seagoing vessel, e.g. to operate refrigeration equipment, or added to the electricity produced in a stationary power plant. Although not shown in this or any of the other embodiments, it is understood that the boilers and steam turbine are part of a steam circuit including a capacitor, a cooler and other components well known in the art of steam power.

An example of the operating parameters of the second embodiment with a MAN B & W® 12K98ME engine is given in Table 1 below. This is a 12-cylinder engine with a 98 cm cylinder bore. It should be noted that the turbocharger compressor plus a possible auxiliary fan requires a power output of approximately 25000 kW. This force is extracted from the exhaust gas and / or supplied by the auxiliary fans.

It is possible to define an optimum value based on the energy extraction from the total system based on energy equations. Ultimately, this depends on conditions such as the nature of the boiler, the nature of the steam turbine and the conditions for using the large two-stroke diesel engine. On seagoing vessels, the focus is mainly on the provision of rotational power, while an application in a stationary power station focuses equally on heat production (for heating neighborhoods) and electricity generation.

The system can be operated at various operating locations with a variable amount of force extracted from the exhaust gas by the first boiler 23 and the power turbine 31.

The force extracted in the first boiler 23 before the turbocharger turbine 6 seen in the flow direction reduces the power available to the turbocharger turbine 6 and the power turbine 31, while the force extracted in the second boiler 20 has no influence on the power of the turbocharger and the power turbine.

In the example of Table 1, an amount of 10,000 kW of energy is extracted in the first boiler 23 for supply to the steam turbine 37 (this amount is selected at random for this example, and other quantities can also be selected, as shown in Figure 3A ).

Figure 3A is a diagram showing the calculation results for different values of the amount of power extracted at the first boiler 23. The diagram shows the power of the individual components as a percentage of the engine shaft power to illustrate the fact that the invention can be used at different engine sizes. . The diagram shows that the power that can be extracted from the power turbine is reduced as the power extracted in the first boiler 23 before the turbocharger turbine 6 seen in the direction of the current increases. The optimum operating point can be determined according to the type of force required (thermal or rotational power / electricity).

If both heating and rotational power are required, such as in stationary power plants that supply both electricity and heat, the optimum operating point is as close as possible to the maximum power extraction via the first boiler 23. This operating point requires the auxiliary blower 16 to be operated even under conditions of full load.

On a seagoing vessel, the required energy is the driving force, ie. rotational force to drive the propeller screw (not shown). The amount of heat energy needed in the vessel is typically relatively low, while the amount of electricity needed varies according to the nature of the vessel. On bulk cargo ships, the amount of electricity needed is relatively low.

Container vessels with freight to be cooled or freight vessels carrying liquefied natural gas need a considerable amount of electrical energy. In these situations, it is advantageous from an overall energy efficiency point of view to operate with 5,000 to 10,000 kW extracted from the first boiler.

Figure 4 shows a third embodiment of the invention. This embodiment is substantially similar to the second embodiment except that the purge air cooler 12a is of a different type. The rinsing air cooler is a washer into which large amounts of water are injected and evaporated. The injected water is preferably relatively hot, e.g. by heating seawater (when the engine is installed in a seagoing vessel) or river water (when the engine is installed in a stationary power plant near a river) with waste heat from the (water) cooling system (not shown) in the engine 1. The washer 12a is operated with it For example, air leaving the washer outlet has a temperature of about 70 ° C and a relative humidity of substantially 100%. The absolute humidity of the rinsing air is about five times higher than that of the rinsing air leaving the intermediate cooler 12 in the second embodiment. Consequently, the amount of energy contained in the purge air and, moreover, in the exhaust gases is substantially increased. Thus, more energy is available for extraction from the exhaust gases by the boilers 20, 23 and the power turbine 31.

An example of the operating parameters of a third embodiment with a MAN B & W® 12K98ME engine is shown in Table 1.

In order to produce this flushing air condition, the turbocharger's compressor and the possible auxiliary blower need a power supply of about 25,000 kW, and in addition, a water injection of about 7.5 kg / s must be provided, which evaporates in the compressor's exhaust air.

This power supply (25,000 kW) must be extracted from the exhaust gas and / or supplied by auxiliary fans.

In this example, 10,000 kW is extracted in the first boiler 23 for delivery to the steam turbine 37 (this amount is selected at random for this example, and other quantities can also be selected, as shown in Figure 4A).

Figure 4A is a diagram showing the calculation results for different values of the amount of energy extracted within the first boiler. The diagram shows the power of the various components as a percentage of the motor shaft power to illustrate the fact that the invention can be applied to different engine sizes. The diagram shows that the power that can be extracted from the power turbine 31 is reduced as the power extracted in the first boiler 23 before the turbocharger turbine 6 seen in the direction of the flow increases. In the present example, more than 25,000 kW can be extracted in the first boiler 23 without the need to apply power to the auxiliary fan 16. In the engine of the second embodiment, only about 14,000 kW can be extracted in the first boiler without is necessary to add power to the auxiliary fan 16. Since the fuel efficiency of the engine itself is only slightly degraded due to the humid and hot rinsing air, the overall fuel efficiency of the engine 1 in combination with the exhaust gas recovery system of the present invention is considerably more efficient than that of a traditional engine. with an exhaust gas recovery system (e.g., the second embodiment). The ideal operating point of the motor according to the third embodiment corresponds to the operating points of the motor according to the second embodiment.

In a variation of the third embodiment, the engine is operated with a very low exhaust gas temperature at the outlet.

These temperatures can be as low as -40 ° C, which means that the water in the exhaust gas undergoes two phase changes: from steam to liquid and from liquid to solid, e.g. contains the exhaust gas leaving the engine, snow or a similar form of ice. In this way, the engine acts as a heat pump, which is particularly interesting for applications where both mechanical energy and heat are needed, such as a combined heat and power plant used to supply electricity and neighborhood heating. This operating state is obtained by extracting a very large amount of energy at the first boiler 23, in the example in Table 1, 72,000 kW is extracted. In addition, the effective area of the turbine 6 is reduced by about one-third compared to the example / embodiment described above, which results in an exhaust gas temperature of -25 ° C. As a consequence of the reduced effective turbine area, the amount of energy available to the compressor 9 is significantly reduced (the temperature drop of the exhaust gas through the turbine (due to gas expansion) increases as the effective turbine area is reduced). In this way, the capacity and energy consumption of the auxiliary fan are increased. In this embodiment, the auxiliary fan 16 is operative in all load conditions, e.g. also at full load, since the power produced by the turbine 6 is not even at full engine load sufficient for compressor 9 to produce all the necessary flushing air.

When the engine is running on heavy fuel oil or diesel fuel, the components of the exhaust section, after the dew point, are designed in the direction of flow with corrosion-resistant materials to withstand the acidic deposits resulting from the sulfur content of these fuels (the condensate contains sulfuric acid).

When operating the engine with natural gas or other fuel that is essentially sulfur-free, such measures are not required.

An example of the operating parameters for this variant of the third embodiment with a MAN B & W® 12K98ME engine is shown in Table 1 of the column "3 cold".

In this variant of the third embodiment, there is no other boiler at the low pressure side due to the low temperatures of the exhaust gas after the turbocharger turbine. Thus, the system contains only the first boiler 23 at the high pressure side of the turbine.

In another variant of this embodiment (not shown), the engine is provided with a second turbine for operation with higher exhaust gas temperatures at both the high and low pressure side of the turbine (for example, between 50 and 200 ° C at the low pressure side and between 150 and 350 ° C at the high pressure side) when the heat demand is less and a higher focus is placed on the rotational force, e.g. in connection with operation in the summer of a combined power and heat plant. The system can either switch to another turbine with a larger effective turbine range than the turbine used to obtain exhaust gas temperatures below ambient temperature, or the other turbine may also have a relatively small effective turbine range, and the two turbines each having a small effective area, is used in parallel and each receives a portion of the exhaust gas flow. During operation with higher exhaust gas temperatures, the turbine with the larger efficient turbine area or the two turbines with a small effective turbine area in parallel operation provides a sufficient amount of power to the compressor, so that the auxiliary fan only needs to be active under low load conditions. The force extracted at the boiler 23 is similarly lowered to obtain that the temperature of the exhaust gases exiting the boiler 23 meets the desired temperature of the exhaust gas at the low pressure side of the turbine 6. Alternatively, a single turbine with a variable efficient turbine (not shown) may be used instead of two turbines to achieve the required flexibility in the efficient turbine range. Thus, this other variant is capable of operating in a mode that focuses on heat production and a very high overall energy efficiency, while the other side focuses on the production of rotational power, and the system is optimized in this mode to have maximum efficiency of the amount. of rotational force that can be extracted from the fuel.

Figure 5 shows a fourth embodiment of the invention. This embodiment is substantially similar to the second embodiment except that the first boiler 23 is located in the exhaust gas stream branched from the exhaust gas line 5. Accordingly, only the branched portion of the exhaust gases passes through the first boiler 23. A conduit 30 directs the exhaust gases from the outlet on the first boiler 23 and to the power turbine 31. The advantage of this embodiment lies in that the exhaust gases can flow from the exhaust gas receiver 3 directly to the turbocharger turbine 6, which means that the engine has a better reaction in connection with accelerations. The outlet of the power turbine 31 is either connected to the inlet of the second boiler 20 or the last part of the exhaust line 21 as shown by the dotted line. The choice of connection depends on the outlet temperature at the power turbine 31. If the outlet temperature at the power turbine 31 is considerably lower than at the turbocharger turbine 6, the outlet on the power turbine is connected to the last part of the exhaust line 21.

An example of the operating parameters of the fourth embodiment with a MAN B & W® 12K98ME engine is shown in Table 1 in column "4".

In this example, 20% of the exhaust gases are branched off against the power turbine, the potential power turbine power take-off (POPT) or the auxiliary blower power supply.

It is possible to determine an optimal value in terms of the power extraction from the overall system. Ultimately, this depends on circumstances such as the nature of the boiler, the nature of the steam turbine, and the conditions of use of the large two-stroke diesel engine. In seagoing vessels, the main focus is on providing rotational power, while when used in a stationary power plant, focus is equally on heat production. (district heating) and electricity generation.

The power available in the exhaust gas flow (160 kg / s) at 455 ° C and 3.35 bar (abs.) Can be utilized in four devices.

1) The first boiler 23 before the turbocharger turbine 6 seen in the direction of flow; 2) the power turbine 31; 3) the second boiler 20 after the turbocharger turbine 6 seen in the direction of flow; and 4) the turbocharger turbine 6.

The system can be operated at various operating points with a variable amount of power extracted from the exhaust gas at the first boiler 23 and the power turbine 31.

The force extracted in the first boiler 23 before the turbocharger turbine 6 seen in the flow direction reduces the power available to the turbocharger turbine 6 and the power turbine 31, while the force extracted in the second boiler 20 has no influence on the force. in the turbocharger and power turbine.

The results for other amounts of energy extracted from the first boiler 23 are shown in the diagram of Figure 5A.

In a variant of the fourth embodiment (not shown), the cooling unit 12 is replaced by a cooling and wetting unit 12a which adds a significant amount of water (steam) to the charging air. In this embodiment, the charging air is not cooled to such a low temperature as in the embodiments without wetting the charging air. The operating parameters for this embodiment are shown in Table 1 in the column "4 humid".

Figure 6 shows a fifth embodiment of the invention. This embodiment is substantially similar to the second embodiment, except that the second boiler 20 is not provided. In addition, the engine is operated at a very low exhaust gas temperature at the outlet. These temperatures can be as low as -40 ° C, which means that the water in the exhaust gas undergoes two phase changes: from steam to liquid and from liquid to solid, e.g. contains the gas leaving the engine, snow or a similar kind of ice. In this way, the engine acts as a heat pump, which is particularly interesting in applications where both mechanical energy and heat are needed, such as in a combined heat and power plant used to supply electricity and heat neighborhoods.

The low temperature of the exhaust gas is obtained by extracting a large amount of energy at the boiler 23 so that the temperature of the exhaust gases leaving the boiler 23 is relatively low. The subsequent expansion of the exhaust gas in the turbocharger causes a further decrease in the exhaust gas temperature. This drop in temperature is not limited to the ambient temperature but can drop significantly below ambient temperature. In this way, the combustion engine is converted into a so-called heat pump, in which low-temperature heat energy is extracted from the surroundings to produce high-temperature heat.

When the engine is running on heavy fuel oil or diesel fuel, the components of the exhaust section after the dew point are constructed in the direction of flow with corrosion-resistant materials so that they can withstand the acidic deposits resulting from the sulfur content of these fuels (the condensate contains SO3 - sulfuric acid).

When operating with natural gas (LNG), LPG, DME, alcohol or other fuel that is essentially sulfur-free, such measures are not required.

In the fifth embodiment, there is no boiler on the low pressure side due to the low temperatures of the exhaust gas after the turbocharger turbine. Thus, the system contains only the first boiler 23 at the high pressure side of the turbine.

An example of the operating parameters of the fifth embodiment using a MAN B & W® 12K98ME engine is shown in Table 1 of the column "5 & 6".

The power available in the exhaust gas stream (160 kg / s at 455 ° C and 3.30 bar (abs.) Is utilized in three devices.

1) The first boiler 23 before the turbocharger turbine 6 seen in the direction of flow; 2) the power turbine 31; and 3) the turbocharger turbine 6

The system can be operated at various operating points with a variable amount of power extracted from the exhaust gas at the first boiler 23 and the power turbine 31.

The force extracted in the first boiler 23 before the turbocharger turbine 6 seen in the direction of flow reduces the power available to the turbocharger turbine 6 and the power turbine 31.

In a variant of the fifth embodiment (not shown), as described above, in connection with the third embodiment, two turbines are provided to also allow the engine to operate at higher exhaust gas temperatures, focusing on the efficiency of the amount of rotational force extracted from the engine. the fuel in relation to the total fuel energy (calculated in relation to the combined heat and power produced by the engine).

Figure 7 shows a sixth embodiment of the invention. This embodiment is similar to the embodiment of Figure 6, except that the turbocharger 8 is omitted. An electrically driven fan 16 '(which can no longer be referred to as "auxiliary fan") pressurizes the purge air. On the exhaust side, an extended power turbine 31' assumes the function of the turbocharger's turbine and delivers electricity via electric generator 32 'to electric drive motor 17', supplying the fan 16 '. Excess electrical energy generated by the extended generator 32' can be used for other purposes. The handling of the electrical energy generated by the generator 32 'can be done by a control unit (not shown) operating The absence of a fixed connection between the turbine and the compressor allows for a more flexible operation of this engine, since the power generated by the power turbine can be more flexibly distributed than by a turbine. a fixed shaft connection between the turbine and the compressor An accumulator system (not shown) such as an electricity Battery can be used to compensate for fluctuations in the amount of energy required for the fan 16 ', thereby improving the engine's response to accelerations, as the delivered fan power can be increased at the same time as an increase in the amount of fuel injected without it being necessary to wait for the reaction of the turbine to the increased exhaust gas flow.

The motor according to the sixth embodiment can be operated flexibly over a range of force values which can be extracted from the boiler 23. In a "winter" setting or operating condition where large amounts of heat are needed for heating the quarters, the motor is thus operated as a heat pump. with exhaust gas temperatures at the outlet well below 0 ° C, and a "summer" setting or operating condition where the engine is not operated as a heat pump and exhaust gas temperatures within a range of between 50 and 200 ° C. For the summer setting, another turbine (not shown) is used in combination with the power turbine 31 'or instead of the power turbine 31', so that the overall effective turbine area is increased. Alternatively, a single turbine with a variable efficient turbine can be used. The change of operating state is also determined by the amount of energy extracted at the boiler 23. The greater the amount of energy extracted at the boiler 23, the lower the temperature of the exhaust gas leaving the turbine.

In the "winter" setting, the different temperatures and pressures correspond to the example provided for the fifth embodiment, cf. Table 1.

In a variation of the sixth embodiment (not shown), turbine 31 'operates a hydraulic pump and fan 16 is driven by a hydraulic motor (instead of an electric generator or motor, respectively). The hydraulic pump and motor may be positive displacement devices, optionally with a variable stroke to provide flexibility. The hydraulic pump and motor are connected to each other via wires and valves controlled by the control unit 27 so that the hydraulic energy supplied by the pump is used to supply the hydraulic motor.

Another variation of the sixth embodiment (not shown) is operated with exhaust gas of 180 ° C and another boiler on the low pressure side of the power turbine 31 'to maximize the efficiency of the "summer" setting. In this case, the engine parameters correspond to the engine parameters of the third embodiment (see Table 1) in the column "3 cold".

Not only can the engine be operated at the two extremes mentioned above, in fact, the engine can be operated at exhaust gas temperatures exiting the turbine at any desired intermediate temperature by adjusting the amount of energy extracted at the boiler 23 and selecting the suitably efficient turbine area corresponding thereto. For this purpose, the engine may also contain two turbines with different efficient turbine ranges, one turbine with a small efficient turbine range and one turbine with a larger efficient turbine range. In this variant, the engine can only be operated with the turbine with the small efficient turbine range at very low exhaust gas temperatures at its low pressure side (winter setting in a combined heat and power plant), only with the turbine with the larger efficient turbine range for intermediate temperatures of the exhaust gas at this low pressure side ( spring / autumn setting in a combined heat and power plant) and with both turbines parallel to high exhaust gas temperatures at the low pressure side of the turbines (summer setting in a combined heat and power plant).

Figure 8 shows a seventh embodiment of the invention. This embodiment is similar to the fourth embodiment. However, the air flow to the turbocharger 8 and the exhaust gas flow from the turbocharger / power turbine in the seventh embodiment is reduced by 20%, with 20% of the exhaust gas being recycled via the first boiler 23, the recirculation line 19, a blower 18 and a washer 18a, back to the flushing system at the conduit 11 before the intermediate cooler 12 seen in the direction of flow. The outlet of the power turbine 31 is either connected to the inlet of the second boiler 20 or the last part of the exhaust line 21 as shown by the dotted line. The choice of connection depends on the outlet temperature at the power turbine 31. If the outlet temperature at the power turbine 31 is significantly lower than the outlet temperature at the turbocharger turbine 6, the outlet at the power turbine is connected to the last part of the exhaust line 21.

An example of the operating parameters of this embodiment using the same engine as in the previous embodiments is shown in Table 1, column "7".

To produce this airflow of 128 kg / s with a flushing air pressure of 3, 6 bar, the turbocharger compressor requires a power supply of approximately 20,000 kW.

The power must be extracted from the exhaust gas at the turbocharger turbine. The exhaust gas contains 22,400 kW. The turbocharger's turbine needs only 20000/22400 x 100% = 89% of the exhaust gas flow to produce the required 20,000 kW. The remaining current of 11% can be used in the power turbine 31. In addition, the exhaust gas recirculation flow represents 20% of the total exhaust gas flow, and all the energy in the streamline can be used in the first boiler 23.

The inlet temperature of the second boiler 20 is variable and depends on the force extracted in the boiler 1 and should not be lower than about 300 ° C since temperatures lower than 300 ° C result in outlet temperatures lower than 180 ° C (if natural gas or other sulfur-free fuel is used, temperatures may be selected lower with condensation and possible freezing of the exhaust gas to maximize overall energy efficiency).

The power of the turbine 31 depends only on the inlet temperature of the power turbine or on how much power is actually extracted in the power boiler inlet string of the first boiler 23.

In addition, the boiler inlet temperature is now a mixture of the turbocharger outlet temperature and the power turbine outlet temperature.

This embodiment is particularly advantageous in that it obtains low ΝΟχ values for the exhaust gas.

TABLE 1

The embodiments described above have been shown with a two stage steam system. However, the system can also be implemented as a single-stage system or as a multi-stage system.

The embodiment in which the boiler is located within the exhaust gas receiver as shown with reference to Figures 1 and 2 can be combined with the other embodiments shown in Figures 3, 3a, 4, 4a, 5-8.

The examples above all relate to an engine running at its maximum continuous engine output (MCR). It should be noted that these motors can run under different loads, which may result in other values for the temperatures and pressures of the intake and exhaust systems.

Although the embodiments and examples above are based on a specific model of a large two-stroke diesel engine, other sizes and types of internal combustion engines may advantageously be used in connection with the inventions described herein.

Typically, the temperatures of the exhaust gases leaving the cylinders in a large two-stroke diesel engine are between 400 and 500 ° C. The pressure in the exhaust gases leaving the cylinders on such an engine is usually higher than 2 bar and is typically between 3 and 4 bar.

The concept of expanding the exhaust gas via the turbine to temperatures lower than ambient temperature can be specifically used for two-stroke and four-stroke internal combustion engines.

The term "contains" as used in the claims does not exclude other elements or steps. The term "one" or "one" as used in the claims does not exclude a majority.

Reference numerals as used in the claims are not to be construed as limiting the scope of the invention.

Although the present invention has been described in detail for the purpose of illustrating it, it should be understood that such details serve this purpose only and that variations in it may be performed by those skilled in the art without departing from the scope of the invention.

Claims (8)

A large turbocharged diesel engine comprising: a plurality of cylinders, each connected to an exhaust gas receiver via their respective manifold tubes, a first exhaust gas line seen in the direction of flow to exhaust the exhaust gases from the exhaust gas receiver to the inlet of the turbocharger turbine, a second exhaust gas line in the direction of flow to direct the exhaust gases from the outlet of the turbocharger turbine into the atmosphere, one or more boilers heated with exhaust gas, or heat exchangers for recovering heat energy from the exhaust gases, characterized in that at least one of the boilers or heat exchangers is located in the exhaust gas receiver. The engine of claim 1, further comprising a preheater boiler on the low-pressure side of the turbocharger and wherein the boiler located within the exhaust gas receiver is used to superheat steam produced by the boiler at the low-pressure side of the turbocharger. An engine according to claim 1 or 2, further comprising a steam turbine powered by steam produced by the boiler or boilers. The engine of claim 3, wherein the power turbine drives an electric generator. An engine according to any one of claims 1 to 4, wherein the exhaust gas receiver contains a plurality of boilers. The engine of claim 5, wherein said plurality of boilers forms a system which produces superheated steam with several steam stages and which contains preheating and superheating boilers. The engine of claim 1, wherein the exhaust gas receiver is divided transversely into an exhaust gas collector duct and a heat exchange duct. An engine according to claim 7, wherein the heat exchange channel has a substantially annular cross-section into which substantially annular segment-shaped boiler sections are accommodated.