WO2023016984A2

WO2023016984A2 - Method for the switching or alternating operation of diesel engines with diesel fuel or a diesel-fuel-and-water emulsion

Info

Publication number: WO2023016984A2
Application number: PCT/EP2022/072225
Authority: WO
Inventors: Ulrich Hilger; Roman Taniel
Original assignee: aqdisol GmbH
Priority date: 2021-08-10
Filing date: 2022-08-08
Publication date: 2023-02-16
Also published as: WO2023016984A3

Abstract

The invention relates to a method for the switching or alternating operation of diesel engines (400), more particularly for the switching operation of marine engines, wherein the diesel engine (400) is operated, in a diesel fuel mode, by the injection of a pure diesel fuel into a combustion chamber of the diesel engine (400) or, in an emulsion mode, by the injection of a diesel-fuel-and-water emulsion, more particularly in accordance with the engine load of the diesel engine (400) and/or the engine power, more particularly as a retrofitting and/or conversion method for retrofitting and/or converting a diesel engine system designed for operation with pure diesel fuel to the switching operation with diesel fuel or with a diesel-fuel-and-water emulsion.

Description

Process for switching or alternating operation of diesel engines with diesel fuel or a diesel fuel-water emulsion

The invention relates to a method for switchover or alternating operation of diesel engines, in particular for switchover operation of ship engines, the diesel engine being operated in diesel fuel mode by injecting pure diesel fuel into a combustion chamber of the diesel engine or in emulsion mode by injecting a diesel fuel-water emulsion , in particular as a function of the engine load of the diesel engine and/or the engine output, in particular as a retrofitting and/or conversion method for retrofitting and/or converting a diesel engine system set up for operation with pure diesel fuel to switchover operation with diesel fuel or with a diesel fuel/water solution -Emulsion.

In addition, the present invention relates to an emulsion circulation system for a diesel engine system, in particular a ship engine system, in particular for retrofitting and/or converting a diesel engine system set up for operation with diesel fuel to switchover operation between diesel fuel operation by injecting pure diesel fuel into a combustion chamber of the diesel engine and emulsion operation by injecting a diesel fuel-water emulsion, in particular for diesel fuel operation or for emulsion operation depending on the engine load of the diesel engine and/or the engine power.

The invention further relates to a retrofitting and/or conversion method for retrofitting and/or converting a diesel engine system set up for operation with diesel fuel to switchover operation of a diesel engine of the diesel engine system with diesel fuel or with a diesel fuel-water emulsion.

Finally, the present invention relates to an injection pump for a diesel engine of a diesel engine system and a diesel engine system with a diesel engine and with an emulsion circulation system and/or with an injection pump.

For the operation of stationary systems, for example for power generation, and the propulsion of ships, for example, for economic reasons mainly used diesel engines. The excellent economy of diesel engines is based on their typically very good level of efficiency and their high level of reliability. These advantages contribute significantly to the relatively low operating costs and low total costs over the entire engine life.

In addition to the economic advantages of diesel engines, ecological challenges are playing an increasingly important role. In particular, the nitrogen oxide (NOx) and soot and particle emissions are considered to be critical pollutant components, which often have comparatively high values, especially in the older engine generations found in sea and inland waterway vessels. A short-term improvement in the emission behavior of existing shipping fleets, for example due to the increased number of new ships being built, is not to be expected due to the long service lives of ships.

However, regulatory measures to promote low-emission propulsion technologies could result in the use of reduced-emission ship propulsion systems being required to ensure freight traffic in the long term. The emission reductions required for this could in principle be achieved by retrofitting existing ships with modern low-emission engines and additionally required exhaust gas after-treatment systems, consisting of relatively large diesel particle filters and DeNOx catalytic converter systems. The replacement of the entire drive train required for this, as well as the exhaust gas aftertreatment systems that can usually hardly be integrated into the existing engine room of older ships, are generally limited to special cases as very cost-intensive retrofitting measures. The same applies to retrofitting engines in older ships with a diesel particle filter and, if possible, also with a DeNOx system.

Methods for using water are attracting increasing interest as a significantly more cost-effective measure for reducing particle and nitrogen oxide emissions within the engine. Here, the effect of the high vaporization enthalpy and higher heat capacity is used to lower the temperature of the cylinder charge and thus on the diesel engine mixture formation and combustion processes to reduce soot and nitrogen oxide emissions. In principle, this also allows one Achieve relief from the technically complex and cost-intensive exhaust gas aftertreatment systems.

Suitable methods for supplying the water into the combustion chamber of the diesel engine are water injection to humidify the intake air, stratified and direct water injection, and injection of a diesel/water emulsion.

Intake air humidification is a simple water injection system. In typically supercharged diesel engines, the water can be injected into the intake system before and after a turbocharger or after an intercooler. The evaporation of the water causes the air sucked into the cylinders to cool, with the thermodynamic efficiency of the cooling decisively depending on the temperature level of the intake air. In addition, in engines with intensive intercooling, some of the water injected into the cylinder will reach the cylinder in liquid form and only lead to a reduction in the charge temperature there. The reduction in nitrogen oxide emissions is then essentially achieved through the lower temperature of the cylinder charge, with a noticeable reduction in NOx emissions only occurring with a relatively high use of water. In addition, the water introduced into the intake system and at least partially evaporated partially displaces the intake air and thus the oxygen required for combustion, so that the local combustion air ratio decreases, particularly in the area of higher engine loads, and thus an increase in soot and particle emissions . This means that intake air humidification is out of the question as the sole method of reducing emissions.

Direct water injection takes place using an additional injector integrated in the cylinder head, through which water is injected into the combustion chamber. By using a water injection system that is decoupled from the diesel injection, water injection quantities and pressure as well as the timing of the water injection can be freely selected. With this method, too, the focus of application is on reducing nitrogen oxides. On the other hand, the disadvantage is the increased expense for a water injection system and the installation space for the additional injector, which is usually not available in series diesel engines with four-valve technology. Stratified water injection is a form of direct injection of diesel fuel and water through a common injector. Stratification can be in the injector or but already take place in the injection system before the injector. The ratio of water and diesel fuel can be quickly adjusted to the engine requirements. The stratified water injection as well as the direct injection of water require a considerable need for adaptation of the engine and injection systems and are therefore less suitable for retrofitting, in particular of ship and stationary engines.

With emulsion injection, an emulsion of diesel fuel and water is injected into the combustion chamber via the injector in the engine's cylinder head. The injection pump designed for diesel operation is generally used here. This means that a costly modification of the cylinder head and, if necessary, a more complex injection system, as in the case of stratified water injection, or the use of an additionally required high-pressure water injection, as in the case of direct water injection, can be dispensed with. There is also a need to supply the engine with a fuel-water emulsion that has a sufficiently homogeneous distribution of the water in the diesel fuel. Emulsions of diesel fuel and water consist of two components that are insoluble in one another. Water forms the disperse phase and is present as droplets in a diesel phase. The water droplets present in the emulsion have a strong tendency to irreversibly coalesce, resulting in high thermodynamic instability of the diesel-water emulsion.

One way to form a stable emulsion of diesel fuel and water is to use emulsifiers, which allow coalescence and aggregation of the water droplets in the mixture, at least over longer periods of time, for example when storing a ready-made emulsion. In the case of larger diesel engines with a relatively high diesel consumption, a higher emulsifier consumption must also be taken into account, which leads to high operating costs.

Another advantageous variant of emulsion injection consists in producing the diesel fuel-water emulsion in the vicinity of the diesel engine, for example on board a ship (on-board), and then within a short period of time, during which the water droplets have not yet coalesced, or to the injection pumps. As a result, the use of an emulsifier to stabilize the emulsion can be completely dispensed with. Also, one Adaptation of the water content in the emulsion to the respective operating conditions of the engine is relatively easy to implement.

The very favorable influence of the diesel-water emulsions on the soot and nitrogen oxide emission behavior can essentially be attributed to the fact that the higher heat of vaporization of the water in conjunction with an increased proportion of inert gas in the form of water vapor leads to reduced combustion chamber temperatures. Since the mixture formation processes that take place in the cylinder, such as the evaporation of fuel droplets and the chemical pre-reactions, are highly temperature-dependent, a reduced charge temperature leads to a slowdown in the mixture formation processes and thus to a longer ignition delay, namely the time interval between the start of fuel injection and the start of combustion. A longer ignition delay means that a longer period of time is available for the mixing and preparation of the injected emulsion fuel with the combustion air in the cylinder, which means that a larger proportion of ignitable prepared fuel-air mixture is present at the beginning of the combustion process. When this "premixed mixture" is burned, there is a significantly lower soot concentration due to the lower proportion of over-enriched mixture zones. During the further diffusion-controlled combustion process, due to the OH radicals formed in emulsion operation through dissociation of the water molecules, there is also an improved post-oxidation of the soot produced, so that overall there is a significantly reduced soot emission.

At the same time, when an emulsion fuel-combustion air mixture is formed, the charge temperatures drop, which, due to heat transport processes, leads to lower combustion temperatures in the mixture zones relevant for the formation of nitrogen oxides in the outer area of the injection jets. Since the NOx formation reactions are highly temperature-dependent, these reduced combustion temperatures lead to a significant reduction in nitrogen oxide emissions, with a corresponding decrease in NOx formation taking place with an increasing water content in the emulsion due to the greater reduction in combustion temperatures.

The lengthening of the ignition delay in emulsion operation at the beginning of combustion also leads to a larger proportion of ignitable prepared mixture with correspondingly higher fuel conversion rates in the first phase of the Combustion and thus to an overall favorable reduction in the overall duration of the combustion process for the thermodynamic process efficiency.

An important prerequisite for using the full emission reduction potential of diesel-water emulsion injection is to control the water content in the emulsion depending on the operating point in such a way that the greatest possible reduction in soot and NOx emissions is achieved with a thermodynamically favorable combustion process at the same time. When the engine is operated in the upper performance range up to full load and thus relatively high combustion chamber temperatures, the emulsion can contain a larger proportion of water in order to achieve a significant reduction in NOx and particle emissions. With a water content of 50% to more than 60%, NOx reductions of more than 50% can be achieved with only slight reductions in consumption. At lower engine loads with correspondingly lower combustion chamber temperatures, a reduction in the proportion of water in the emulsion is necessary in order to avoid excessively lengthening the ignition delay and combustion duration with correspondingly increased emissions of unburned fuel up to and including ignition misfires.

DE 44 12965 A1 discloses a method and a device for operating a diesel engine with a diesel fuel-water emulsion to reduce nitrogen oxide and soot emissions. With increasing water content, an increasing reduction in nitrogen oxide and soot emissions is achieved. At low engine loads, however, increased hydrocarbon (HC) and carbon monoxide (CO) emissions occur as a result of deteriorated combustion, so that the higher water content in the emulsion, which is advantageous for high engine loads, must be reduced in the low-load range. An emulsion supply system is therefore proposed that allows the water content in the emulsion to be adjusted to the engine operating range. However, the generation of the emulsion before the injection pump of the diesel engine leads to a sluggish response, e.g. due to the storage of an emulsion in the emulsifying device and the transport lines, so that the emulsion does not have the desired optimum water content when the engine load changes.

In the proposed emulsification supply system, water is injected under pressure into a mixing chamber in a ratio specified by a control unit and mixed with diesel fuel. The mixing chamber is in a "recirculation system" to supply the engine injection pump and return of excess fuel to the mixing chamber. Due to a relatively large storage volume, this type of emulsifying system has a relatively high responsiveness to changes in the water content in the emulsion. Therefore, according to DE 44 129 65 A1, an additional reservoir divided by a membrane is introduced, in which diesel fuel and emulsion fuel are temporarily stored separately. With the stored diesel fuel, the injection pump can then be flushed when the load is reduced by appropriately switched valves, thus achieving rapid displacement of the emulsion. Conversely, when the engine load increases, the stored emulsion can reduce the proportion of diesel in the injection pump and thus quickly switch to emulsion operation with a higher proportion of water. This emulsification supply system also allows switching to pure diesel operation by displacing the emulsion fuel from the injection pump. In addition to the relatively complex structure of the emulsion supply, it is very difficult to set a composition of the fuel during load changes that is defined by the engine characteristics map.

EP 0 742 363 B1 discloses a method for mixing and pumping diesel fuel-water emulsions, which is designed for use, for example, in large ship diesel engines. The aim of this process is to reduce nitrogen oxide and soot emissions as cost-effectively as possible using the existing fuel injection system, which is designed for diesel operation.

The emulsion supply system consists of a diesel pump and a water pump for dosing the water content in the emulsion, which is then formed in an emulsification plant, depending on the operating point. This emulsion is then fed through a delivery line to the injection pumps of the diesel engine. In a further variant, an increase in the emulsion throughput in the injection pumps is proposed to improve the control behavior. The excess quantity that is then not injected is fed back into a separation plant, in which the emulsion fuel is separated again into the components diesel fuel and water and stored in buffer tanks. The amount of fuel and water that is used is fed from the storage tanks into the buffer tanks, from which diesel fuel and water are then fed to the dosing system. The known method for operating the diesel engine with an emulsion fuel is based on utilizing the maximum delivery capacity of the injection pumps designed for diesel fuel operation. The lower fuel requirement of the engine in the lower load range and the resulting overcapacity of the injection pumps allows the water content in the emulsion to be increased up to the limit of the pumps' delivery capacity. Accordingly, the engine performance is determined at least in the lower load range by the water content in the emulsion fuel. However, it must be taken into account that, at least at very low engine loads, there is a combustion-related quantity limit for the water content. This mode of operation should be possible up to about 50% of the engine load. If the engine load is increased further, the proportion of water in the emulsion must be reduced, with only pure diesel fuel being injected in the full-load range. With this concept, an injection quantity that is as constant as possible should be achieved so that the atomization of the fuel through the injection nozzles corresponds to the optimum design conditions over the entire load range of the engine.

This proposed method for operation with emulsion fuels requires complex engine control to avoid excessive water content in the emulsion and for load control. In particular, the water content in the low load range must be adjusted so that the ignition delay does not become too long, which would result in excessive pollutant emissions from incomplete combustion. At high engine loads and the associated higher nitrogen oxide emissions, the water content in the emulsion is too low. Overall, this well-known concept does not achieve the emission-reducing potential of fuel-water injection. Taking into account the area of application for large engines, the proposed emulsion process could only be used in conjunction with other exhaust gas aftertreatment processes for a sufficient reduction in nitrogen oxides.

It is known that the greatest reduction in nitrogen oxide emissions and soot emissions can be achieved with emulsion injection in relation to the use of water. With a water content of up to 60%, soot and NOx reductions of well over 50% can be achieved, depending on how the injection system is tuned. However, such a high proportion of water leads to a significant reduction in the energy content of the emulsion. An operation with higher engine power, as is often necessary for the mountain journey of ships on inland waters, is only possible with a simultaneous significant reduction in the water content in the emulsion. This means that the potential for reducing emissions is used much less effectively.

It is known from DE 10 2018 126 095 A1 to provide water injection in the intake line of the engine in addition to the emulsion injection method in order to achieve a reduction in combustion chamber temperatures, which is primarily necessary to reduce NOx emissions, despite limited water content in the emulsion. In this method, which can be used additively, the water injection should take place, for example, upstream or downstream of the exhaust gas turbocharger or downstream of the intercooler, and thus cooling of the air sucked into the combustion chamber. This is intended to bring about a reduction in the combustion temperatures in the NOx formation zones in the combustion chamber. Due to the evaporation of the injected water, which occurs for the most part or even completely in the intake system, and the associated increase in volume, part of the intake fresh charge is displaced. This means that less oxygen gets into the combustion chamber, so that if large quantities of water are injected, soot emissions can increase again.

According to DE 10 2018 126 095 A1, a further limitation of the amount of water injected into the intake line results from the risk of liquid water separating out due to condensation. Therefore, the relative humidity of the charge air should be below the saturation line existing at the respective charge air temperature. However, in ship engines, for example, the intake air temperature behind the intercooler, which is generally supplied with cold river or sea water, is around 40°C at such a low level that even with relatively small amounts of injected water, condensation of the water in the intake line can occur .

Document EP 2 772 640 A1 discloses a method for switching or alternating operation of diesel engines, with the diesel engine in diesel fuel operation by injecting a pure diesel fuel into a combustion chamber of the diesel engine or in emulsion operation by injecting a diesel fuel-water emulsion is operated. There is an emulsion circulation system for a diesel fuel-water emulsion provided that a metering unit for metering emulsifying water and diesel fuel in the emulsion circulation system and an emulsifying unit for emulsifying emulsifying water and Has diesel fuel. In addition, a switching device for operating the diesel engine with diesel fuel or with a diesel fuel-water emulsion is provided, with emulsion operation taking a diesel fuel-water emulsion from a circulation line of the emulsion circulation system via at least one extraction point and feeding it to an injection pump of the diesel engine.

DE 338 449 A discloses a method for operating ship and boat engines with direct water injection, the heat of the combustion products being used to distill sea water and the distilled sea water being used as injection water for the engine.

DE 10 2019 209 639 A1 discloses a component for an injector for fuel and/or water injection in Otto engines, which has a metallic base material and a coating arranged at least in sections on the base material, the coating comprising at least one oxide of at least one valve metal or wherein the coating is a ceramic coating.

DE 10 2010 003 886 A1 relates to a high-pressure pump with a pump assembly and a drive shaft, which has at least one cam assigned to the pump assembly. Here, the pump assembly includes a roller running on a running surface of the cam and a roller shoe that receives the roller. At least one anti-corrosion layer is provided on the roller, the roller shoe or the cam. This can prevent vibration cracking corrosion from occurring during operation, which can lead to breakouts near the surface under load and consequently to failure of the high-pressure pump.

The object of the present invention is to provide a method for switchover operation of a diesel engine and an emulsion circulation system for diesel engine systems, in particular for ship engine systems, which compared to the prior art improve the operation of diesel engines with pure diesel fuel in diesel fuel operation or allow with diesel fuel-water emulsions in an emulsion operation and in particular a simplified and inexpensive retrofitting and / or conversion of existing diesel engine systems, especially ship engine systems, for optional Enable operation with diesel fuel or with diesel fuel-water emulsions.

The object of the present invention is, in particular, to specify an emulsion injection method that is particularly suitable for retrofitting and/or converting larger diesel engines and a correspondingly designed and set up, in particular retrofitted and/or converted, diesel engine system that allows diesel engines with a Operating point adjustable composition of a fuel-water emulsion to operate with high efficiency and disadvantages of performance at higher, required for improved exhaust emission behavior, to avoid or at least reduce water content in the emulsion. In particular, the disadvantages of an injection system tailored to large injection quantities for alternating operation with pure diesel fuel or with diesel fuel-water emulsions are to be avoided.

Finally, another object of the present invention is to provide an injection pump for diesel engines of a diesel engine system and a diesel engine system that enable simplified and economical diesel fuel operation or emulsion operation of the diesel engine.

The above objects are achieved according to the invention by a method for switchover operation of diesel engines with the features of claim 1, claim 5 or claim 10, an emulsion circulation system with the features of claim 11, a retrofitting and / or conversion method for retrofitting and / or converting a diesel engine system set up for operation with pure diesel fuel to switchover operation with the features of claim 12, by an injection pump with the features of claim 15 and by a diesel engine system with the features of claim 16. Advantageous configurations of the invention are the subject matter of the dependent claims.

In order to solve the aforementioned problems, the invention provides an emulsion circulation system for a diesel fuel-water emulsion in a method for switching or alternating operation of diesel engines of the type mentioned at the outset. The emulsion circulation system can be used when retrofitting or converting a diesel engine system that is designed and set up for operation with pure diesel fuel, or also when a new diesel engine system is installed be integrated into the system periphery. According to the invention, the emulsion circulation system has a metering unit for metering emulsification water and diesel fuel into the emulsion circulation system and an emulsification unit for emulsifying emulsification water and diesel fuel. A PLC-based controller can be provided to control the dosing unit and/or the emulsifying unit.

The emulsion circulation system also has at least one switchover device, in particular designed as a valve device, more particularly as a switchover valve, for operating the diesel engine with diesel fuel or with a diesel fuel-water emulsion in particular as a function of load and/or power. According to the invention it is further provided that in emulsion operation a diesel fuel-water emulsion is taken from a circulating line of the emulsion circulating system via at least one extraction point and fed to an injection pump of the diesel engine.

According to a first aspect of the invention, the diesel fuel-water emulsion is fed into the circulating line of the emulsifying unit at a constant flow rate during emulsion operation.

In the methods known from the prior art, due to the removal of diesel fuel-water emulsion from a circulating line in emulsion operation, there are fluctuations in the flow rate, especially in the area upstream of the emulsifying unit, which has disadvantages in the production of the emulsion, especially when using static mixers. In order to ensure that the emulsifying unit or the mixer of diesel fuel and emulsifying water works at the optimum operating point, even if different amounts of the diesel fuel-water emulsion are removed from the circulation line in emulsion operation, volume compensation of the emulsion circulation system is carried out according to the invention in emulsion operation taken and supplied to the injection pump by metering in diesel fuel and/or by metering in a regulated quantity of emulsifying water into the emulsion circulation system, so that in emulsion operation the diesel fuel-water emulsion is fed at a constant flow rate in the circulation line of the emulsifying unit. As a result, changes in the flow rate of the diesel fuel-water emulsion in the circulation line due to the removal of diesel fuel-water emulsion can be compensated for. The volume compensation preferably takes place continuously. Preferably, an automatic volume compensation is provided by controlled dosing of water and/or diesel fuel, which can preferably be added via the dosing unit. Alternatively, it can also be supplied via a storage device in which a diesel fuel/water emulsion with a specific composition is stored.

The emulsion circulation system forms a closed system, with diesel fuel and/or emulsifying water and/or a diesel fuel-water emulsion being fed back into the emulsion circulation system to ensure constant volume between the dosing unit and emulsifying unit. In this way, the emulsion losses occurring in emulsion operation due to the removal of emulsion from the emulsion circulation system can be compensated.

In emulsion operation, the flow rate of the diesel fuel-water emulsion in the circulating line is preferably kept constant by volume equalization in the line section from the dosing unit to the emulsifying unit, in particular to the extraction point. A "constant" flow rate within the meaning of the invention is related to the line cross-section at the respective location of the circulating line. According to the invention, the flow rate can change when the line cross-section changes in the circulation line. At the respective location of the circulating line, i.e. with a constant line cross-section, the flow rate in emulsion operation remains constant due to the volume compensation described, with a decrease in flow rate due to the emulsion removal from the circulating system of the order of less than 10%, preferably less than 5%, can fall under the term "constant flow rate".

For example, it is possible for the flow velocity and/or the pressure in the circulating line to be measured at at least one point in the circulating line, preferably at different points. If there is a (slight) decrease in flow velocity and/or line pressure due to the removal of the emulsion from the circulating line, this can automatically lead to diesel fuel and/or emulsifying water being fed into the circulating line via the dosing unit. Following the law of communicating tubes, backfeed can occur simply due to a decrease in the line pressure in the circulation line. If there is a drop in pressure in the circulating line due to the volume being removed via the engine's injection pump, diesel fuel and/or emulsifying water can be pumped out of the fuel supply line or the water supply line simply because of the existing differential pressure between the circulating line and the fuel supply line or the water supply line. In particular, no pump is required to establish the volume compensation.

In particular, the volume equalization ensures a constant inflow speed of the emulsifying unit.

In emulsion operation in particular, a constant flow rate of the diesel fuel-water emulsion in the circulation line from the dosing unit to the emulsifying unit, in particular to the extraction point, of at least 2.0 m/s, preferably at least 2.5 m/s, more preferably at least 3 .0 m/s to 5.0 m/s.

In emulsion mode, a volume flow of a diesel fuel-water emulsion can be provided or adjusted in the circulation line from the dosing unit to the emulsifying unit, in particular up to the extraction point, which is at least 1.5 times the volume flow, preferably at least twice the more preferably at least 2.5 times to at least 3 times or more, at maximum emulsion removal or the maximum engine consumption in emulsion operation.

The flow rate of the emulsion in the circulation line of the circulation system is preferably kept constant, at least from the dosing unit to the emulsifying unit and beyond to the extraction point(s) of the injection pump, which is achieved in particular by the above-described volume or quantity equalization of the emulsion circulation system in Emulsion mode extracted diesel fuel water emulsion can be achieved by supplying fuel and / or emulsifying water via the metering unit. In this way, a constant inflow velocity can be set or guaranteed in the emulsion circulation system upstream of the emulsifying unit, independently of the emulsion removal by the diesel engine. The constant inflow speed allows the advantageous use of very robust and maintenance-free working mechanical mixers. The energy required for the mixing process can be provided by the kinetic energy of the flow. The inventive method can in this Connection provide a preferably only fluidic emulsification of fuel and emulsifying water in a mechanical mixer. Accordingly, the emulsifying unit of the dosing and emulsifying device of the emissions circulation system according to the invention has at least one mechanical mixer or exclusively mechanical mixers for the emulsification. It is expedient if the mixer is arranged downstream of the dosing unit, in particular downstream of a circulation pump of the emulsion circulation system. Since the mixing quality of the emulsion produced with a mechanical mixer depends to a large extent on the kinetic energy of the flow, the constant flow conditions mean that the mixer design can be optimally adjusted for uniformly good comminution and homogenization of the water droplets present in the raw emulsion at the mixer inlet.

In principle, emulsifying devices that require the supply of external energy can also be used. If, instead of a mechanical mixer, emulsifying devices that are largely insensitive to the inflow velocity, such as rotor, stator and/or high-pressure emulsifying devices, are used, in which the energy required for emulsification is not supplied or is not supplied solely via the flow energy of the material flow to be mixed , the excess emulsion quantity in the circulation system can be reduced or adjusted to the emulsion consumption. However, the high flow rate to the injection pumps required for low transport delay must be maintained by appropriate design of the pipe cross-sections.

The emulsion circulation system has, in particular, a circulation line designed as a ring line or as a circulation line, in which the dosing unit, the emulsifying unit and the switching device and, preferably, a circulation pump are fluidically integrated and in which a diesel fuel-water emulsion circulates in emulsion mode.

A "constant" flow rate of the diesel fuel-water emulsion in the circulating line should preferably also be present within the meaning of the invention if there are changes in the flow rate of less than +/- 10 percent, preferably less than +/- 5 percent, more preferably less than 2%, comm. Appropriate switchover valves can be used to switch quickly, cylinder by cylinder, between the fuel supply to the injection pump from the emulsion circulation system and a fuel supply line for pure diesel operation. Alternatively, the changeover can also be achieved by a centrally arranged changeover valve in conjunction with non-return valves on the injection pumps.

According to the device, a correspondingly designed and set up emulsion circulation system for diesel engine systems, in particular ship engine systems, is proposed that has a dosing and emulsifying device with a dosing and premixing unit, preferably a circulating pump, and an emulsifying unit downstream of the dosing unit. In the metering unit, diesel fuel and/or emulsifying water is metered in at a required fuel-water ratio, in particular in accordance with the set engine load and/or the engine output. The supply of an injection pump or several injection pumps of the diesel engine with pure diesel fuel or with a diesel fuel-water emulsion takes place via the switching device using a valve device via one or more tapping points in the emulsion circulation system. The extraction can take place via at least one valve which connects a circulating line of the circulating system to an injection pump or also to several injection pumps and via which the diesel fuel-water emulsion is fed to the injection pump or injection pumps. The switchover device preferably has at least one switchover valve that can be connected or switched to a circulation line of the circulation system or a diesel fuel supply line, depending on the operation. In emulsion operation, a diesel fuel-water emulsion can then be taken from the circulation line via the switching valve and fed to the injection pump, while in diesel fuel operation, pure diesel fuel is taken from the diesel fuel supply line and pure diesel fuel is fed to the injection pump.

In the context of the present description of the invention, the term “pure diesel fuel” or “diesel fuel on its own is to be understood as non-water-enriched diesel fuel, in particular to be understood as fuel that is not present in the form of a diesel fuel-water emulsion.

According to the invention, a modular emulsion circulation system is proposed that has a dosing and emulsifying device integrated therein. The emulsion circulation system according to the invention advantageously consists of individual modules adapted to the emulsion consumption of the engine, which are adapted to the small space available in ships.

The dosing and emulsifying device is set up or designed to produce an emulsion fuel with variable water proportions and allows a set water proportion of the emulsion to be changed when the load or performance of the diesel engine changes with a slight time delay. The emulsion circulation system according to the invention has a switching system with at least one switching device, so that load- and/or output-dependent operation of the diesel engine with diesel fuel or with emulsion is made possible. In particular in connection with an injection system according to the invention described below, which is designed to utilize the combustion-technically possible emission-reducing properties of diesel-water emulsions, in particular at high engine loads up to reaching the nominal load, the injection of emulsion fuels with correspondingly high water contents of at least 45 to 50% or more may be possible, in particular with an intended increase in the delivery capacity of the injection pump(s) of the injection system compared to the delivery capacity of injection pumps designed for pure diesel operation.

The emulsion circulation system according to the invention has, at least in a line section of a circulation line in which a fuel-water emulsion is conducted from the metering unit to the engine during emulsion operation, at least after the metering unit and a (changeover) valve of the circulation line, an area with a high flow rate of the pumped Emulsion to ensure rapid emulsion transport to the diesel engine injection pump. This ensures a short dwell time for the emulsion on the way to the injection pump, which on the one hand prevents coagulation of the emulsion and on the other hand enables a correspondingly short time delay between the operating point-dependent change in the water content in the metering unit and the availability of the changed emulsion composition at the injection pump of the diesel engine. The required relatively high transport speed of the emulsion can be achieved by a high, constant flow rate of a circulating pump of the emulsion circulating system in conjunction with appropriately designed pipe cross-sections. The quantity of emulsion not consumed by the diesel engine can remain in the circulation system, so that an emulsion admission pressure required for filling the pump elements of the injection pumps is obtained via an overflow regulator or a pressure control valve. The volume content of the emulsion circulation system is preferably kept constant. For this purpose, as described above, a preferably continuous equalization of the diesel fuel-water emulsion taken from the emulsion circulation system in emulsion operation and fed to the injection pump(s) can be achieved by metering diesel fuel and/or by metering a controlled amount of emulsifying water into the emulsion circulation system via the Dosing unit may be provided, wherein the regulation of the amount of emulsifying water can take place according to a diesel fuel/emulsifying water ratio predetermined by the load point and/or the power of the diesel engine. For this purpose, a correspondingly designed and set up measuring, control and/or regulating device can be provided.

The amount of emulsifying water, which is supplied via the dosing unit to compensate for the diesel fuel-water emulsion taken from the emulsion circulation system in emulsion operation and fed to the injection pump(s), depends on the performance-related diesel fuel consumption and, on the other hand, corresponds to the amount required for an optimal reduction of the soot and nitrogen oxide emissions for the respective operating point required water proportion. The water content can be precisely controlled by comparing measured volume flows of diesel fuel and water supplied via the metering unit with the target values for the water content stored in an electronic control unit, for example in an engine load/speed map. Depending on the engine mode of operation and the sensors used, the map operating points can be defined either, as with directly driven ship propellers, according to the propeller performance curve only by the engine speed or, in simplified form, by the measured diesel fuel volume flow or by a combination of engine speed and engine load or fuel delivery quantity of the injection pumps.

The proposed dosing concept can be used particularly advantageously when retrofitting diesel engines if, for example, the existing diesel supply system continues to be used and therefore no additional diesel pre-supply pump and no additional dosing pump for the emulsion water are required.

The engine at operating temperature is generally operated with a composition of the water-diesel emulsion that is adapted to the load condition. Here, at high engine loads and correspondingly high combustion and engine temperatures, the greatest possible reduction in NOx and soot emissions is sought through a high water content in the emulsion of at least 40% to 50% or more. The upper limit of the water content is essentially given by a delayed combustion process with a corresponding deterioration in the thermal efficiency as well as increasing carbon monoxide and soot emissions.

The water content in the emulsion fuel is increased via the dosing unit, with which an additional amount of water is added to the emulsion in the circulation system. This emulsion formed with a higher proportion of water reaches the injection pumps of the engine after a short time delay due to the high transport speed provided according to the invention in the circulating system. In this way, good transient behavior of the diesel engine with regard to exhaust emissions can be achieved, for example in ship operation.

When the engine load is reduced, an emulsion with too high a water content for the lower load point can be present in the circulation system. When the engine load is reduced, for example by a maximum of up to 50 percent to 70 percent compared to full load, the emulsion in the circulation system, which still has a higher water content corresponding to the previous higher load point, can be mixed with the dosing unit, based on the supplied diesel fuel, lower water content are added. Due to the fact that the emulsion is removed by the engine when the load is not reduced to values that are too low, the excess water content in the circulating emulsion is then reduced as a result of engine consumption, with the reduction in combustion temperature occurring due to the excess water content only having a minor effect on the engine due to thermal inertia combustion process.

Diesel fuel can be taken from a diesel tank with a fuel pump and fed to the metering unit with a constant admission pressure of the fuel pump via a fuel supply line. In the metering unit, the diesel fuel can be metered into a circulating line of the emulsion circulating system, the circulating line being connected to the fuel supply line. If the pressure in the circulating line before the dosing unit drops due to the volume being removed via the engine's injection pump, diesel fuel can flow out of the fuel supply line simply because of the differential pressure between the circulation line and the fuel supply line are replenished. Particularly preferably, no pump is required to meter diesel fuel from the fuel supply line into the circulation line. A regulated supply of emulsifying water into the circulating line increases the line pressure so that correspondingly less diesel fuel is replenished. If no emulsifying water is pumped into the emulsion circulation system, only diesel fuel is preferably supplied. In this context, the emulsion circulation system according to the invention can provide that a diesel fuel supply line connected to a diesel tank opens into a circulation line of the emulsion circulation system and that automatic metering of diesel fuel into the circulation line is preferably only based on the resulting differential pressure between a fuel admission pressure in the diesel fuel supply line and the pressure level in the circulation line he follows.

In the event of a greater reduction in engine load to very low or near-zero load load values or engine power and/or when a certain speed jump is reached depending on the nominal speed, for example when the speed decreases by 50 to 100 rpm in relation to a nominal speed of 800 to 1,200 ,00 rpm, in particular 1,000 rpm, and/or with a speed decrease of 10 to 25 rpm based on a nominal speed of 150 to 300 rpm, in particular 200 to 250 rpm, increases due to the then im Circulation system too high a water content in connection with the correspondingly low fuel quantities taken from the emulsion circulation system due to engine consumption, the time delay before the water content in the emulsion is adjusted. In order to ensure a rapid change in the water content of the emulsion in the circulation system up to pure diesel operation and thus a consistently good combustion process and good emission behavior, it can be provided according to an alternative aspect of the invention that depending on the load point and / or the power of the diesel engine, in particular when the power changes to no-load or low-load operation, and/or when a certain speed jump is reached, the diesel fuel-water emulsion contained in the emulsion circulation system is preferably completely discharged from the emulsion circulation system and then, more preferably, stored.

The complete discharge can affect all emulsion-carrying lines of the emulsion circulation system, at least a ring line with which the fuel is conveyed back from the metering unit to the diesel engine and from the diesel engine in the direction of the metering unit. A switching valve can be used for removal be provided. For example, it can be provided that the emulsion circulation system is supplied with an emulsion adapted to the actual load point and/or the actual performance of the diesel engine by flushing the emulsion circulation system with a diesel fuel-water emulsion with a modified water content or with pure diesel fuel.

A diesel fuel-water emulsion with a changed water content can be produced by appropriate dosing of emulsifying water and diesel fuel via the dosing unit and emulsification in the emulsifying unit and fed to the emulsion circulating system, preferably essentially at the same time as the discharge or drainage of a diesel fuel-water emulsion from the emulsion circulating system or pure diesel fuel can be fed to the emulsion circulation system substantially contemporaneously with the discharge.

In the case of load changes, in particular in the event of a load decrease, the diesel engine can be supplied with a diesel fuel-water emulsion with a modified water content and adapted to the current load point and/or the current output of the diesel engine, or pure diesel fuel, with the delay in the supply of an adapted diesel fuel Water emulsion and / or pure diesel fuel for diesel engine can be specified essentially only by the transport speed of the emulsion or diesel fuel in the emulsion circulation system.

Preferably, the delay time in an adjustment of the generated diesel fuel-water emulsion or the supply of pure diesel fuel starting at the time of a load point change to the time at which a diesel fuel-water emulsion with the water content adapted to the changed load point is present on the engine and is fed in, less than 10 seconds, preferably less than 6 seconds, more preferably less than 4 seconds, up to less than 1.0 seconds, the delay time depending on the distance from the location at which the diesel fuel-water emulsion is generated, from the installation order of the engine. The smallest possible distance is preferably provided in order to achieve a short delay time.

While the diesel fuel-water emulsion contained in the emulsion circulation system is quickly removed at higher speeds due to the higher engine consumption, according to the invention, in particular when there is a load decrease and/or in In the lower to medium load range, the emulsion contained in the emulsion circulation system is discharged and replaced by an emulsion with a modified water content, which is then fed to the engine. In particular, the ejection takes place only in no-load or extremely low-load operation. The discharge of the diesel fuel-water emulsion present in the emulsion circulation system with an unadapted water content and the formation of an emulsion with an adapted water content and supply to the engine or the supply of pure diesel fuel to the engine can preferably take place essentially at the same time. This ensures that the engine is supplied with as little interruption as possible with a diesel fuel/water emulsion adapted to the load point and/or the power of the diesel engine, or else with pure diesel fuel. An adjustment of the composition of the diesel fuel-water emulsion in the emulsion circulation system to a changed load point and/or a changed performance of the diesel engine, in particular in the lower and medium speed range, can be particularly preferred by discharging the diesel fuel-water emulsion contained in the emulsion circulation system and preferably forming it at the same time an emulsion with an adjusted water content and supply line to the diesel engine via the emulsion circulation system can be provided if the speed decreases by at least 70 percent to 90 percent compared to the nominal speed of the diesel engine at which the diesel engine achieves maximum power.

Preferably, at the same time as the diesel fuel-water emulsion present in the emulsion circulation system is discharged, a fuel-water emulsion with a changed water content corresponding to the changed load point and/or the changed performance of the diesel fuel machine can be produced in the metering and emulsifying device and fed to the emulsion circulation system. For a quick adjustment of the water content in the emulsion supplied to the engine, the emulsion volume present in a circulation line can be completely discharged and stored in an intermediate emulsion storage tank or emulsion collection tank, while at the same time the diesel-water emulsion corresponding to the load point or the engine line is made available by the metering unit and reaches the motor at high transport speed. As a result, the time delay with which the respective emulsion reaches the engine is the same at high and also very low engine loads and only depends on the transport speed in the emulsion circulation system. If the emulsion volume from the emulsion circulation system is completely fed into the emulsion collection tank and the emulsifying water supply to the dosing unit is interrupted at the same time, the discharged circulation volume can also be completely replaced with pure diesel fuel. As a result, emulsion operation can be ended very quickly and converted to diesel operation. In addition, it prevents water residues from remaining in the emulsion-carrying lines and the injection system, which means that the engine can be started up again without any problems even if the engine has been idle for a long time.

The emulsifying circulating system according to the invention can provide a device for rinsing the circulating system using a switching valve and for filling an emulsion collection container with level monitoring. The flushing process can be monitored by a flow meter and the flushing process is preferably continued until the entire volume of the circulating system has been flushed into the collection container. The volume of the collection container can be measured in such a way that, for example, five or more, further for example ten, consecutive flushing processes are possible. Furthermore, a device for metering back the contents of the collection container into the circulating system can only be provided when the emulsion is in operation.

The emulsion circulation system according to the invention can have a control and/or regulating device for controlling and/or regulating the metering of diesel fuel and/or emulsifying water into the emulsion circulation system depending on the diesel fuel-water emulsion taken from the emulsion circulation system in emulsion operation. In particular, the emulsion circulation system according to the invention can provide an emulsion collection container or buffer and a measuring, control and/or regulating device with which the filling and/or emptying of the emulsion collection container is carried out as a function of fill level measurements in the container and/or flow measurements in a circulation line of the emulsion circulation system is controlled and/or regulated.

An expedient development of the method according to the invention can provide for the diesel fuel-water emulsion discharged from the emulsion circulation system to be stored and for the stored diesel fuel-water emulsion to be fed back into the emulsion circulation system with a time delay, with the feed-back preferably being carried out using a volumetric Consumption of the diesel engine related volume flow of 2.5% to 15%, preferably from 5% to 10%. To empty the emulsion collection tank, which serves as an intermediate store, the storage contents are then preferably continuously removed from the collection tank during emulsion operation of the diesel engine, for example by a metering pump, and can, preferably, be pumped into the water inlet of the metering unit. Due to the small amount of recirculated storage content, the deviation in the resulting water metering has no or only a negligible effect on the operating behavior of the diesel engine. It goes without saying that a corresponding adjustment of the measurement, control and/or regulation system is provided in order to control and/or regulate the previously described partial emptying of the emulsion collection container.

River water, brackish water or sea water can be used as emulsifying water, in particular with river water, brackish water or sea water being treated before use, in particular desalinated, further in particular using a reverse osmosis process, with the treated river water, brackish water or sea water being stored and/or with river water , brackish water or seawater is taken from the environment during operation of the diesel engine and processed "on board" and/or as required. For water treatment, in particular desalination, a diesel engine system according to the invention can have a water treatment system. Desalination can preferably be carried out using a reverse osmosis system which, in contrast to ion exchangers, does not require any auxiliary substances such as salts or bases. The membranes of the reverse osmosis system, like a pump to generate the required water pressure, can be adapted to the salt content of the raw water. This enables system operation, for example in the area of use of a ship in river water, brackish water or sea water, or even blue water. To control and/or regulate the raw water supply and desalination of the emulsion water, a correspondingly designed measuring, control and/or regulating device can be provided, for example a PLC-based controller.

Another possibility for the targeted lowering of the charge temperatures and thus in particular for the reduction of nitrogen oxides is to supply water to the engine's intake system. Known methods use the heat of vaporization to reduce the intake air temperature by humidifying the intake air with water injected into the intake system, for example upstream or downstream of the intercooler. Since, in particular, supercharged ship engines with are equipped with at least one charge air cooler that can work with sea or river water as a cooling medium, relatively low charge air temperatures of less than 50 °C are already achieved. Therefore, the temperature reduction that can be achieved through condensation of the injected water is already severely limited in the intake manifold or in the air plenum.

A further aspect of the present invention relates to a method for switching operation of a diesel engine, with a direct supply of water being provided adjacent to the combustion chamber or a combustion chamber or cylinder of the diesel engine. In particular, the present invention relates to a method in which a direct supply of water into an inlet port of a cylinder head of the diesel engine is provided. Accordingly, the diesel engine can have at least one cylinder head with a valve arrangement having at least one inlet valve, preferably several inlet valves arranged one behind the other in the direction of flow, with water being fed directly into an inlet channel inside the cylinder head. Directly feeding water into the intake port inside the cylinder head directly adjacent to the combustion chamber or a combustion chamber of the diesel engine ensures that the water gets into the combustion chamber during an intake process and evaporates there or very close to the combustion chamber.

According to the invention, water is injected beyond a connection plane of the cylinder head for an intake manifold. In an intake manifold or intake air plenum, an intake port injection nozzle can be arranged, which can extend from the outside through the intake port of the intake manifold to the connection level or beyond into the interior of the cylinder head, so that an atomizer nozzle for water injection can be injected directly into the intake port on the Connection level is or in the area of the intake port inside the cylinder head and thus beyond a connection level of the cylinder head for the intake manifold.

Clocked water injection is particularly preferred.

The droplet size of the water injected can be, for example, between 10 and 100 μm, based on the Sauter diameter of the droplets. A particularly effective water injection can be achieved when the central axis of the intake port injection nozzle or the main flow direction of the injected water lies on the central axis of the intake port or is arranged centrally to or in the intake port.

A control and/or regulation device for the automatic control and/or regulation of the water injection can be provided.

The water that is brought in just before the intake valves can get into the cylinder as liquid droplets during the intake process, where it essentially leads to a significant reduction in charge temperatures due to rapid and complete evaporation. The water in the intake port is preferably atomized with a nozzle immediately before it enters the combustion chamber. A reduction in the gas temperatures in the combustion zones of the fuel-air mixture that are relevant for NOx formation is thus also achieved via heat transport processes. Due to the direct cooling of the cylinder charge, a comparatively small amount of water is required for NOx reduction compared to the supply into the intake air plenum further away from the combustion chamber, for example behind the intercooler. In addition, the limitation of the injected water quantity is independent of the saturation of the air humidified in the intake manifold and largely only dependent on the influence on the combustion process. Since the method according to the invention can be applied precisely and quickly to an operating point via a map control, there is the advantageous possibility of supplementing the emulsion injection, which has a somewhat slower control behavior.

Water is preferably supplied via the intake duct only in the medium load range to the full load range of the diesel engine. The usable speed range of the diesel engine can be, for example, in the range between 600 rpm and 1,000 rpm, with a water supply preferably being provided via the inlet channel only in the speed range between 700 rpm until the rated speed of, for example, 1,000 rpm is reached can be. Particularly preferred in the medium load range to high load range is a ratio of the amount of water introduced into the intake port to the amount of water supplied to the combustion chamber with the diesel fuel-water emulsion of 0.5 to less than or equal to 1.0, in particular substantially the same amount of water is supplied via the inlet channel and via the emulsion, with, preferably, deviations of +/- 10 percent being tolerable. Idle at lower At engine speeds up to the medium load range, the ratio of the water quantity supplied via the intake port to the water quantity supplied via the diesel fuel-water emulsion can be less than 0.5. When idling up to the medium load range, there is no need for a water supply via the intake port. For example, no water supply can be provided via the inlet channel in the lower speed range of, for example, less than 700 rpm.

According to the device, the diesel engine system according to the invention accordingly has a water injection device, designed and arranged for water injection into the inlet port of a cylinder head of the diesel engine adjacent to the inlet into the combustion chamber, so that the injected water during operation of the diesel engine preferably predominantly in liquid form during an intake process in the Combustion chamber reached.

The water pressure of up to 16 bar provided by an emulsifying water supply can preferably be used for continuous atomization of the water and for volume regulation. Instead of a continuous injection of the water, an intermittent injection can also be provided for further improved atomization of the water.

The calorific value of the emulsion fuel decreases with increasing water content. In order to achieve a performance behavior corresponding to basic diesel operation, it can therefore be provided according to the invention to increase the fuel quantity injected into the combustion chamber of the diesel engine in emulsion operation.

A large proportion of larger diesel engines for stationary or mobile use, for example as ship propulsion systems, are equipped with pump-line-nozzle (PLD) injection systems in which an injection pump supplies one cylinder with fuel via an injection line and the injector. An injection pump consists of a housing in which a pump element consisting of a pump cylinder and a pump piston are integrated. The pump piston is driven via a roller tappet mounted in the engine block, for example, by a special cam of the engine camshaft assigned to each pump. The flow rate and thus the engine output are regulated by a pump element that works according to the well-known overflow principle in conjunction with a bevel edge control to change the useful stroke. The rotation of the pump piston required for this takes place via a driver sleeve through an im Pump housing slidably mounted control rod, which is driven by an engine speed controller, for example. With this type of controller, which is often used in ship operation, for example, the engine speed is controlled at a constant value in accordance with a specified setpoint and within the power limits of the engine.

The pumping of the fuel that has previously been sucked into the pressure chamber of the pump element through the inlet bores begins when the inlet bores are closed by the upward movement of the pump piston. After the pressure has built up, it is pumped via a pressure valve into the injection line and then injected by the injector. Depending on the position of the control edge and the corresponding useful stroke, the end of delivery is reached when the fuel pressure in the pressure chamber of the pump element is reduced through the inlet bores released by the pump piston via an overflow groove into the suction chamber.

A further aspect of the invention, which can preferably be combined with the aforementioned aspects, relates to a retrofitting and/or conversion method for retrofitting and/or converting a diesel engine system set up for operation with diesel fuel to switchover operation of a diesel engine of the diesel engine system with or with diesel fuel a diesel fuel-water emulsion, in particular for diesel fuel operation or emulsion operation depending on the engine load of the diesel engine and/or the engine power, in particular for retrofitting and/or converting ship engines, with an injection pump selected and set up to operate the diesel engine with pure diesel fuel Diesel engine is replaced by a retrofit and / or replacement injection pump, which has a certain enlarged inner diameter of a pump cylinder of the injection pump and an enlarged outer diameter of a pump piston of the one may have injection pump. The increase in the outside diameter of the pump piston of the injection pump is preferably limited to 5 percent to 20 percent, preferably up to 10 percent, based on the diameter of an injection pump set up to operate with pure diesel fuel.

Alternatively or in particular additionally, an injection pump with a pump piston with a control edge geometry that is equally adapted to operation with a diesel fuel/water emulsion and operation with pure diesel fuel can be provided. An increase in the inner diameter of the pump cylinder of the injection pump and the outer diameter of the pump piston as well as a modification of the control edge geometry of a pump element are preferably provided, which works according to the known overflow principle in conjunction with a bevel edge control for changing the useful stroke. When converting to diesel fuel/water emulsion operation, an increase in the piston diameter with a corresponding adjustment of the position of the control edge can be considered to increase the maximum injection quantity for economic reasons. Since the sensitivity of the engine controller is adjusted to the basic diesel operation, the larger the piston diameter, the greater the change in the flow rate in relation to the travel of the control rod. In the event of changes, for example in the engine speed, this leads to brief overshoots in accordance with the dynamic control behavior and thus to a greater increase in the injection quantity, combined with the risk of increased soot formation. In addition, due to the limited control accuracy, there are large fluctuations in the fuel injection quantities.

The increase in the inner diameter of the pump cylinder and/or the outer diameter of the pump piston and/or the modification of the control edge geometry described above are to be understood in relation to the inner diameter of the pump cylinder and outer diameter of the pump piston as well as the control edge geometry of the pump piston of an injection pump that is designed for pure diesel fuel operation .

By changing the control edge geometry according to the invention or by using an injection pump with a pump piston that has such an adapted control edge geometry, the change in the delivery rate related to the control rod travel can be adapted to diesel or emulsion operation (alternating operation). Preferably, the modification of the control edge geometry at a lower control edge can provide a first control edge section with a lower control edge gradient for a lower delivery volume in diesel fuel operation and a second control edge section with a larger control edge gradient for a larger delivery volume in emulsion operation. The pump piston can have a lower control edge slope suitable for diesel operation, so that, for example, an increase in the control rod travel required to increase the delivery rate causes a reduced delivery rate change compared to a straight control edge. For bigger Delivery quantities, such as are required for emulsion operation, the pump piston is twisted by a corresponding further increase in the control rod travel in the area of a significantly steeper control edge. This achieves the quantity increase required for the higher load range of the engine. In this case, the area of the control edge in the lower area of the piston torsion angle, which is used in diesel operation, has a lower gradient, while a steeper control edge is provided for controlling the much larger injection quantities in emulsion operation, corresponding to the larger torsion angle of the pump piston. Despite the larger pump piston diameter in the area of smaller control rod travel, an injection quantity profile that is largely comparable to that of the basic diesel injection pump is achieved, while in the subsequent area the additional injection quantities required for emulsion operation can be provided when the control rod travel is increased. The injection nozzle used in the emulsion injection system can be adapted to a larger injection quantity spread, so that low-emission combustion can also be achieved in diesel operation.

In order to prevent the pump controller from overshooting in areas of the control edge in pure diesel operation, in which too large quantities of diesel fuel can be associated with corresponding disadvantages in terms of soot or particle emissions, a limitation of the control rod travel controlled by the engine map can be provided. In emulsion operation, this limitation of the amount of diesel can be withdrawn depending on the engine load and the proportion of water, for example in a stepwise or continuously controlled manner. The control rod travel of a control rod provided for rotating the pump piston can accordingly be limited according to the invention to limit the delivery volume in diesel fuel operation and a larger control rod travel, in particular the maximum control rod travel, can be released for a larger delivery volume flow in emulsion operation.

With the fuel-water emulsion process according to the invention, it is possible to achieve a considerable reduction in soot and nitrogen oxide emissions and possibly somewhat more favorable fuel consumption values due to the high proportion of water that can be used, particularly at high engine outputs. However, the improvement in emission behavior that can actually be achieved depends on the tuning of the injection system and the combustion process. Especially when retrofitting or converting older engines with relatively high initial values for the nitrogen oxide emissions, it can be advantageous to use further measures to improve the pollutant emission behavior in addition to emulsion operation. The invention therefore preferably provides a further and/or alternative possibility for modifying the control edge geometry of a pump piston of the injection pump. An additional control edge can be arranged on the upper edge of the pump piston in the torsion area for high emulsion injection quantities. As a result, in emulsion operation, a delay in the start of delivery is used to further reduce nitrogen oxide emissions.

According to the invention, the pump piston can have a first upper control edge for the start of injection formed by the transition from an end face to the outer surface of the pump piston, the modification of the control edge geometry in addition to the first upper control edge at least one upper area that is recessed axially with respect to the first upper control edge and has at least one second upper control edge can provide for retarding the start of injection, and wherein, preferably, the second upper control edge is arranged in the area axially above a lower control edge for emulsion operation, so that the start of injection is retarded in emulsion operation.

Due to high NOx emissions in the upper load range in particular, a delay in the start of fuel delivery can be provided for further reducing the combustion temperatures and thus the NOx emissions. A longer ignition delay in emulsion operation with a correspondingly larger proportion of premixed fuel-air mixture and the resulting shorter combustion period, especially in the higher load range, allows the injection to be moderately shifted in the "retarded" direction, with a limit essentially being set by the delay that is too great the start of injection occurring deterioration in efficiency is given. In pure diesel operation, on the other hand, even a slight delay in the start of injection does not make sense because of the delayed combustion that occurs and the correspondingly worse efficiency behavior and increasing soot emissions.

The start of delivery can be delayed according to the invention by an additional "overhead" control edge, which separates the pressure chamber of the pump element from the inlet bore somewhat later during the upward movement of the pump piston, so that the injection pressure can build up. The start of delivery can be shifted by approx. 2 to 5 degrees reach crank angle. Since the retardation of the start of delivery should only take place in the upper load range of emulsion operation, the upper control edge is accordingly arranged above the control edge for regulating the quantity of the emulsion fuel. The retardation can thus advantageously be limited to the upper load range in emulsion operation.

With a combination of increasing the piston diameter and increasing the useful stroke by adjusting the control edge on the pump piston to end the pumping process, the diameter adjustment on the pump piston can be smaller. This also allows the load on a roller tappet to drive the pump piston to be reduced.

A switchable or controllable control rod travel limiter can be used to limit the diesel fuel injection quantities in the corresponding control edge area. In the case of a map-dependent larger injection quantity in emulsion operation, an increased or the entire control rod travel is released. The release can take place in particular as a function of the charging pressure and/or the water content of the emulsion. A method according to the invention can accordingly provide that a modification of the control rod travel of a control rod provided for rotating the pump piston is provided, with the control rod travel being limited to limit the delivery volume flow in diesel fuel operation and with a larger control rod travel, in particular the maximum control rod travel, being required for a larger delivery volume flow in emulsion operation. is provided. An SBS-based controller can be provided to control the control rod stops.

An injection pump according to the invention for a diesel engine provides a pump piston with a modified control edge geometry and/or with a previously described limitation of the control rod travel.

A pump piston of an injection pump and/or a valve needle of an injection valve of the diesel engine can have a wear-reducing coating and/or an anti-corrosion coating in certain areas. To reduce the increased wear on the pump piston in emulsion operation and on the valve needle of the injection valve in the injector, the corresponding surfaces can be provided with a wear-reducing coating, in particular a CLD or carbon-like diamond coating. This wear protection Layering in connection with compared to standard pump element and nozzle fits lead to a comparatively considerably longer service life of these components. In this context, the invention relates to a retrofitting and/or conversion method, in which an injection pump of the diesel engine that is set up for operation with diesel fuel is replaced by a retrofitting and/or replacement injection pump that has a pump piston with a wear-reducing coating and/or anti-corrosion coating provided at least in certain areas having. Alternatively or additionally, as part of retrofitting and/or conversion, an injection valve of the diesel engine that is set up for operation with diesel fuel can be replaced with a retrofit and/or replacement injection valve that has a valve needle with a wear-reducing coating and/or anti-corrosion coating provided at least in certain areas.

The coatings also provide very good corrosion protection. All other components of the injection system and the emulsion supply system that come into contact with the diesel-water emulsion fuel, such as emulsion-carrying pipes and valves, can be protected by using stainless steels or pipes or a surface coating with e.g. Nickel must be protected against corrosion and consist of corrosion-resistant steels, especially in the area of higher pressures. In the low-pressure area, for example in the area of emulsion water treatment, plastic pipes and/or corrugated hoses, for example made of EPDM or Teflon, can be used as flexible connections.

In addition, a cooling device can be provided in order to protect the fuel-water emulsion in the emulsion circulation system against excessive heating and thus to avoid a reduction in the emulsion stability.

The invention is explained below by way of example with reference to the drawing. Show in the drawing

1 shows a system diagram of an embodiment of a diesel engine system with an emulsion circulation system of the type according to the invention for supplying the diesel engine with a fuel-water emulsion for a 6-cylinder engine and provided emulsifying water supply devices; 2 shows a basic illustration of a fuel injection pump with a pump piston with a control edge geometry modified according to the invention;

FIG. 2A shows an individual illustration of the pump piston of the fuel injection pump from FIG. 2;

3 shows an example of the course of the injection quantity as a function of the travel of the control rod when using a pump piston with a modified control edge course according to FIG. 2 provided according to the invention;

4 shows a basic illustration of a further pump piston for a fuel injection pump with a control edge geometry modified according to the invention;

5 shows a schematic diagram of an additional water injection into the intake port of a cylinder head of a diesel engine, for example the diesel engine system shown in FIG. 1, and

6 shows a schematic representation of a control device for a fuel-water emulsion supply system.

Fig. 1 shows a schematic representation of an emulsion supply system that is particularly suitable for retrofitting ship engines, consisting of the components of a pump unit (100) for removing the raw water and the components of an emulsifying water treatment (200) for the subsequent treatment and storage of the desalinated water to supply a Emulsification plant (300). The emulsifying system (300) supplies a diesel engine (400) in emulsion operation with a diesel fuel-water emulsion via a circulation line designed as a ring line (401). A fuel-water metering unit (314), an emulsion circulation pump (306) and an emulsifier (309) are fluidically integrated into the circulation line (401) and form components of an emulsion circulation system. In addition, the emulsion circulation system has a number of changeover valves (405.1-6), which are provided to supply the cylinders of the diesel engine (400) with a diesel fuel-water emulsion in emulsion mode or with pure diesel fuel in diesel mode of the diesel engine (400). In emulsion operation, the diesel fuel-water Emulsion from the circulation line (401) and the supply line. The diesel engine (400) is supplied by removing emulsion fuel from the circulating line (401) and feeding it to the fuel injection pump (402) of the diesel engine (400).

All system components are individually scalable and can therefore be adapted to the required emulsion fuel requirement of the engine(s) as well as to the available installation space and the extraction options for sea or river water, for example. The emulsion supply system is controlled or regulated by a PLC-based control and regulation unit (500) based on a PLC, which is connected to sensors and actuators.

The control and regulation unit (500) of all components of the emulsification supply system is operated via an operating unit (501).

Further parts and components of the pump unit (100), the emulsifying water treatment (200), the emulsifying system (300) and the diesel engine (400) can be found in the list of reference numbers.

As a central component of the emulsion supply system, the emulsification system (300) includes components of the emulsion circulation system and components of an emulsion storage unit (314). The circulating line (401) forms an emulsion circuit and is designed as a ring line. Within the emulsifying system (300), the emulsion circulating in the circulation line (401) in the fuel-water dosing unit (301) can be supplied with diesel fuel via a fuel pump (409) from a fuel tank (408) and emulsifying water. The emulsifying water is metered by a water metering valve (303) which, according to a measured diesel fuel throughput, feeds an amount of water corresponding to the operating point to the emulsion circulation system. To regulate the proportion of water, a target value from a characteristic map that is stored in the control and regulation unit (500) is compared with measured diesel and water volume flows and corrected accordingly. A water volume measuring unit (302) and a fuel volume measuring device (304) are provided for this purpose. The supplied and pre-mixed mixture of diesel fuel and emulsifying water reaches the emulsifier (309) via an emulsion circulation pump (306), which is preferably designed as a flow-mechanical mixer. With this very low-maintenance mixer design, emulsification takes place without the addition of additional energy the kinetic energy of the flow. The corresponding pressure losses are compensated for by the emulsion circulation pump (306).

By designing the circulation line (401) and the emulsion circulation system for a volume flow between the metering unit (301) and the diesel engine (400), which is preferably 1.5 to 2 times or greater multiple of the maximum emulsion consumption of the diesel engine (400) in Corresponds to emulsion operation, a constant high flow rate is achieved regardless of the fuel extraction by the diesel engine (400). Accordingly, there is a relatively short time lag between the increase in the proportion of water in the dosing unit (301) and the entry of the emulsion into the fuel injection pumps (402) of the diesel engine (400).

With the emulsion circulation system, it is possible very quickly to operate the diesel engine (400) either in pure diesel fuel operation or in emulsion operation. In diesel fuel operation, pure diesel fuel is fed to the fuel injection pumps (402) via the switching valves (405) via a fuel supply line (404), which is already present in retrofitted diesel engines (400). This allows the diesel engine (400) to be switched very quickly from emulsion operation to pure diesel operation. This possibility of switching the operating mode is necessary for reasons of operational safety in ship operation. In addition, the direct switchover between diesel and emulsion operation via the switchover valves (405) advantageously enables, in addition to an emergency shutdown of the emulsion supply required for safety reasons, the starting process of the diesel process (400) in diesel operation as well as the operation of the emulsion circuit pump (306) to replace the emulsion contained in the circulation system by diesel fuel.

When changing to operating points with lower engine loads, the water content in the emulsion must be reduced. The emulsion volume contained in the circulation system with the water content corresponding to the higher engine load can generally be replaced by an emulsion with a lower water content due to the consumption of the diesel engine (400). However, given the low volumetric fuel consumption in the low-load range, this adaptation process to low water proportions proceeds slowly, so that the emulsion fuel contained in the circulating system is discharged into the emulsion (temporary) storage unit (314). About a purge valve (310) is the entire or at least a sufficiently large proportion of the emulsion fuel contained in the circulation system is fed into an emulsion collection tank (315) or flushed out. In this case, after reaching an emulsion volume detected by an emulsion flushing quantity measuring device (317) or after a predetermined time, the discharge of the emulsion from the circulating system is terminated. Parallel to the discharge of the circulating volume, diesel fuel is supplied via the metering unit (301) and water is supplied corresponding to the lower load point. If the water supply is shut off, the entire circulation system can also be filled with diesel fuel. On the one hand, this enables the engine to be restarted in pure diesel operation and, on the other hand, the emulsion remaining in the circulation system is prevented from disintegrating if the engine is not running for a long time.

Pure diesel operation of the diesel engine (400) is nevertheless possible for special operating states, for example in the low-load range or in warm-up phases that may be required, as well as in emergency operation. The injection system of the diesel engine (400) is therefore designed and set up both for diesel operation and for emulsion operation with a very high proportion of water. Accordingly, the delivery capacity of the fuel injection pumps (402) can be adapted to injection quantities that are up to 50 or 60% larger in emulsion operation. The increase in the delivery quantity of the fuel injection pumps (402) can be achieved with a constant cam lift, in particular via a larger pump piston diameter of the fuel injection pumps (402).

To improve the engine control behavior in diesel operation and to represent large injection quantities in emulsion operation, the control edge geometry of the pump piston of the fuel injection pump (402) according to FIG. 2 can have a modified profile. Fig. 2 shows schematically a diesel engine (601) with an injection pump housing (602) in which an intermediate tappet (603) for a pump piston (612) of an injection pump of the diesel engine (601) and a pump cylinder (604) are accommodated. The pump piston (612) is movably guided in the pump cylinder (604). In the embodiment of the fuel inlet pump (402) shown, the pump cylinder (604) has two bores (605, 611) for the fuel inlet and outlet. These bores (605, 611) are connected to a suction chamber (610) surrounding the pump cylinder (604). When delivery begins, the fuel pressure in a pump working chamber or pressure chamber (609) is increased during the stroke movement of the pump piston (612) until a pressure valve (606) opens and fuel or a fuel-water emulsion is injected via an injection pressure line to a Injector flows. Incidentally, Fig. 2 shows a pressure valve holder (607) and an injection power connection (608).

The pump piston (612) has an axial longitudinal groove (617) on the outside of its piston skirt. The pump piston (612) also has a control groove area (618). The upper edge of the control groove area (618) facing the pressure chamber (609) forms a lower control edge (613, 614) and the edge of the end face (619) of the pump piston (612) forms an upper control edge (620). During the pump stroke, the two control edges (613, 614, 620) interact with the control bores (605, 611) in such a way that the start and end of delivery of the fuel injection pump are determined during the pump piston stroke by releasing or closing the control bores (605, 611). are.

According to FIG. 2A, a flatter control edge section (613) is provided for the diesel operating range, so that the change in quantity when the pump piston rotates with a control rod (not shown) is lower in accordance with the higher energy content of the diesel fuel. On the other hand, in emulsion operation at high engine loads and larger proportions of water, a greater increase in the delivery volume is provided, so that the control edge in the emulsion operating range has a control edge section (614) with a steeper progression.

Due to the faster combustion process in emulsion operation and thus without a thermodynamically unfavorable delay in the end of combustion, a further reduction in NOx emissions can be achieved by starting delivery later. According to Fig. 4, the control edge geometry of the pump piston (612) for retarding the start of injection can, in addition to the first upper control edge (620), have an overhead area (621) that is recessed axially with respect to the first upper control edge (620) and has at least one second upper control edge (616) exhibit. During the upward movement of the pump piston (612), the second upper control edge (616) causes the bores (605, 611) in the pump cylinder (604) to close later and thus to a later start of the injection pressure build-up in the pressure chamber (609).

Figure 5 shows a section through part of the intake system of a larger diesel engine (400). The charge air, compressed and cooled by an exhaust gas turbocharger, flows through an air collector (702) to the intake manifold outlets or intake manifolds (703) of the cylinders of the diesel engine (400). According to FIG. 5, another possibility for reducing nitrogen oxides is water injection directly into an intake port (710) in a cylinder head (701) of the diesel engine 400. In this case, treated and pressurized clean water (707) is used, for example a supply line (214) according to Fig. 1 is taken, via a pressurized water volume control (320) and optionally a further pressure increase of an atomizer nozzle (706) shown in Fig. 5. The pure water drawn off via the supply line (214) reaches the atomizer nozzle (706) via a water supply line (705).

The intake manifold (703) delimits an intake channel (711) for the charge air. An intake port injection nozzle (712) is guided through the intake manifold (703), and the atomizer nozzle (706) is arranged at the cylinder-side end of this nozzle. The atomizer nozzle (706) is designed as a mist nozzle and is aligned with the inlet channel (710) in the cylinder head (701) of the diesel engine (400).

As a result, pure water (707) is directly fed into the intake port (710) of the cylinder head (701) immediately adjacent to a first intake valve (713), with part of the intake air water feed (708) also being fed into the intake area of a second intake valve (714) arrived.

Water is injected beyond a connection plane Y of the cylinder head (701) for an intake manifold flange (704) of the intake manifold (703). The distance between the connection plane Y and the center axis X of the first inlet valve (713) can be between 100 and 150 mm or less. The nozzle exit of the atomizer nozzle (706) is on the Y connection level in the embodiment shown, so that water is injected beyond the Y connection level. However, the outlet opening of the atomizer nozzle (706) can also lie beyond the connection plane Y in the area within the inlet channel (710) of the cylinder head (701), ie it can be shifted to the left with reference to FIG. The distance between the nozzle opening and the first inlet valve (713) is selected in such a way that pure water (707) enters the combustion chamber as water mist (709) and thus preferably predominantly in liquid form during an intake process of the diesel engine (400). The arrow (708) in Fig. 5 shows schematically the intake air water supply to the intake valves (713, 714) of the diesel engine (400). As can also be seen from FIG. 5, the central axis Z of the intake port injection nozzle (712) can be arranged on the central axis of the inlet port (710), so that the atomizer nozzle (706) is arranged centrally to or in the inlet port (710).

The dosing unit (301) shown in FIG. 1 is supplied with treated emulsifying water (214) from an emulsifying water reservoir (211). For this purpose, in the case of a ship installation, the pump unit (100) sucks in water or raw water (201) from the outside via a feed pump (103) and feeds it to a fine filter (202). The filtered raw water (201) is fed to a desalination plant (205) for subsequent desalination, which includes a reverse osmosis (RO) plant (206). With the help of a conductivity sensor (209), the conductance of the pure water (208) obtained by reverse osmosis or of the permeate is determined and the degree of desalination is thus determined. The conductance of the emulsifying water should preferably not exceed 20 pS/cm, since the salts fed to the diesel engine (400) with the emulsifying water can contribute to an increase in the particle emissions produced during combustion and to deposits in the injection system. A conductance of 20 pS/cm corresponds to that of distilled water. In special cases, a mixed-bed ion exchanger can also be installed downstream of the RO system (206) to ensure a very low salt content.

The membranes used in the RO system (206) are matched to the salt content of the raw water (201) sucked in via the pump unit (100). Therefore, the salt content or the corresponding conductivity of the raw water (201) is continuously monitored by a conductivity sensor (104) of the pump unit (100). If the permissible salt content is exceeded, the electronic control (500) of the emulsion supply system causes the delivery rate of the feed pump (103) to be reduced and the bypass valve 105 to the disposal line 106 to open. The feed pump (103) is not switched on again until the measured conductance is again below a permissible value. Shorter interruptions in the water supply can be bridged by the emulsifying water reservoir (211).

When retrofitting ship engines, the desalination system (205) to be used can be adapted accordingly due to the modular design of the emulsion supply system according to FIG. The control of the emulsion supply system as well as the control rod travel limitation provided on the fuel injection pumps (402) is carried out by the central control and regulation unit (500) with interfaces to an operating unit (501) and to the power supply. The individual measurement inputs and control outputs are shown in FIG. It goes without saying that the signal inputs and control outputs shown are selected as examples.

The engine speed is essentially required for the operating point-dependent control of the proportion of water when using ship engines. The corresponding engine power results from the propeller curve, taking into account the propeller design. The engine load or the engine torque can be determined via the injection quantity detected by means of a control rod displacement sensor. The proportion of water is then stored in a map as a function of the engine speed and possibly the engine load in the control and regulation unit (500).

The water content in the emulsion is regulated by measuring the flow rate of the supplied diesel fuel and emulsifying water, with the water content being adjusted by the metering valve (303) controlled by the control and regulation unit (500). Furthermore, for the advantageous limitation of the injection quantities, particularly in diesel operation, a control rod travel limitation controlled via the engine characteristics map is used. In addition, the control and monitoring of the emulsifying water treatment (200) based on the guide values of raw and emulsifying water as well as the pump monitoring are integrated in the control and regulation unit (500). Finally, some temperatures and system pressures for monitoring the emulsion supply system and the diesel engine (400) are recorded in the control and regulation unit (500) and fault messages are displayed if faults occur.

The operating states of the emulsion supply system, including an emergency control, are switched via the control and regulation unit (500) or the operating unit (501). In this way, all safety requirements, for example in ship operations, can be met. Switching on the emulsion mode, which is generally done manually, is controlled or regulated according to a sequence program stored in the control and regulation unit (500), the circulating pumps of the circulatory system, which initially only contains diesel fuel, being switched on first. Then the changeover to emulsion operation takes place via the corresponding changeover valves (405) in front of the injection pumps (402) and then the setting of the water content corresponding to the operating point. If the engine speed falls below a limit, corresponding to a very low load or if the emulsion mode is switched off, the emulsion in the circulating system is then discharged via the flushing valve (310) into the emulsion buffer store (314) and replaced by an emulsion with a correspondingly lower water content or by diesel fuel. The duration of the rinsing process is specified by the emulsion rinsing quantity measurement or is time-controlled. When switched off, the emulsion system is always filled with pure diesel fuel to avoid emulsion separation and accumulation of water in parts of the system and any deposits that may occur.

3 shows an example of the course of the injection quantity as a function of the control rod travel of a control rod used to rotate the pump piston (612), the pump piston (612) having a control edge geometry of the type shown in FIGS. 2 and 2A. The injection quantity curve is shown schematically for an emulsion injection pump with an optimized control edge according to FIGS. 2 and 2A in comparison to the injection quantity curve when using a diesel injection pump with a standard control edge for diesel operation. Despite the larger pump piston diameter in area A, the emulsion injection pump achieves an injection quantity curve that is largely comparable to that of the basic diesel injection pump, while in area B the additional injection quantities required for emulsion operation can be provided. A pump characteristics map is assigned to area A, which controls the operation of the diesel engine (400) with pure diesel fuel, and area B is the operating area in emulsion operation of the diesel engine (400).

Reference number:

100 pump unit 311 cooler

101 main plant valve 312 emulsifying water supply

102 raw water filter 40 313 pressure regulator

103 feed pump 314 emulsion storage unit

104 conductivity sensor 315 emulsion collection tank

105 bypass valve 316 return dosing pump

106 return manifold 317 emulsion flushing quantity measurement unit

45 direction

200 processing 318 level sensor

201 raw water 319 supply line

202 fine filter 32Q pressurized water volume control

203 pretreated emulsifying water

204 backwash water 50 400 diesel engine

205 desalination plant 401 circulation line

206 RO system 402 fuel injection pumps

207 concentrate drain 403 fuel injector

208 pure water 404 fuel supply line

209 conductivity sensor 55 405 switching valve

210 emulsifying water supply 406 injection nozzle leakage collection

211 emulsifying water storage line

212 level measurement 408 fuel tank

213 clean water pump 409 fuel pump

214 emulsifying water

500 control and regulation unit

300 emulsifying plant 501 control unit

301 fuel-water metering unit

302 water volume measuring device 601 diesel engine

303 water metering valve ⁶⁵ 602 injection pump housing

304 Fuel volume measuring device 603 Intermediate tappet

305 pre-mixer 604 pump cylinder

306 emulsion circulation pump 605 bore

307 vent valve 606 pressure valve

308 fuel supply ⁷⁰ 607 pressure valve holder

309 emulsification unit 608 injection power connection

310 purge valve 609 pressure chamber 610 suction chamber 702 air collector

611 bore 15 703 intake manifold

612 pump piston 704 intake manifold flange

613 control edge section 705 water supply line 614 control edge section 706 atomizing nozzle

616 control edge 707 pure water

617 longitudinal groove 20 708 intake air

618 control groove area 709 water mist

619 face 710 intake port 620 upper control edge 711 intake port

621 area 712 intake port injector

25 713 intake valve

701 cylinder head

Claims

45 patent claims:

1 . Method for switching or alternating operation of diesel engines (400), in particular for switching operation of ship engines, the diesel engine (400) in diesel fuel operation by injecting a pure diesel fuel into a combustion chamber of the diesel engine (400) or in emulsion operation by injecting a diesel fuel Water emulsion is operated, in particular as a function of the engine load of the diesel engine (400) and/or the engine power, in particular as a retrofitting and/or conversion method for retrofitting and/or converting a diesel engine system set up for operation with pure diesel fuel to switchover operation with diesel fuel or with a diesel fuel-water emulsion,

- where an emulsion circulation system for a diesel fuel-water emulsion is provided and/or retrofitted,

- wherein the emulsion circulation system has a metering unit (301) for metering emulsifying water and diesel fuel into the emulsion circulation system and an emulsifying unit (309) for emulsifying emulsifying water and diesel fuel,

- wherein the emulsion circulation system further comprises at least one switching device (405) for load- and/or power-dependent operation of the diesel engine (400) with diesel fuel or with a diesel fuel-water emulsion,

- wherein in emulsion operation a diesel fuel-water emulsion is taken from a circulating line (401) of the emulsion circulating system via at least one extraction point and fed to an injection pump (402) of the diesel engine (400) and

- wherein in emulsion operation a volume equalization of the diesel fuel-water emulsion taken from the emulsion circulation system in emulsion operation and fed to the injection pump (402) is provided by metering diesel fuel and/or by metering a controlled amount of emulsifying water (214) into the emulsion circulation system, so that the diesel fuel - water emulsion is fed to the emulsifying unit (309) in emulsion mode at a constant flow rate. 46

2. The method according to claim 1, characterized in that the flow rate of the diesel fuel-water emulsion in the circulating line (401) in emulsion operation is kept constant by volume compensation from the dosing unit (301) to the emulsifying unit (309), in particular to the extraction point .

3. The method according to claim 1 or 2, characterized in that a constant flow rate from the dosing unit (301) to the emulsifying unit (309), in particular to the removal point, of at least 2.0 m/s is achieved by the volume compensation in emulsion operation.

4. The method according to any one of the preceding claims, characterized in that in emulsion operation a volume flow of a diesel fuel-water emulsion is provided in the circulation line (401) from the dosing unit (301) to the emulsifying unit (309), in particular to the extraction point, which corresponds to at least 1.5 times the volume flow at maximum emulsion removal in emulsion operation.

5. Method for switching or alternating operation of diesel engines (400), in particular for switching operation of ship engines, the diesel engine (400) in diesel fuel operation by injecting a pure diesel fuel into a combustion chamber of the diesel engine (400) or in emulsion operation by injecting a Diesel fuel-water emulsion is operated, in particular as a function of the engine load of the diesel engine (400) and/or the engine power, in particular as a retrofitting and/or conversion method for retrofitting and/or converting a diesel engine system set up for operation with pure diesel fuel switchover operation with diesel fuel or with a diesel fuel-water emulsion, in particular according to one of the preceding claims,

- wherein the emulsion circulation system has a metering unit (301) for metering emulsifying water and diesel fuel into the emulsion circulation system and an emulsifying unit (309) for emulsifying emulsifying water and diesel fuel, 47

- Wherein a load point and/or power change of the diesel engine (400), in particular when changing to no-load or low-load operation, more particularly when a certain absolute value of the speed change is reached, the diesel fuel-water emulsion contained in the emulsion circulation system is preferably completely removed from the Emulsion circulation system is derived.

6. The method according to claim 5, characterized in that a diesel fuel-water emulsion with a changed water content is preferably essentially simultaneously with the discharge of a diesel fuel-water emulsion from the emulsion circulation system by appropriate metering of emulsifying water and diesel fuel via the metering unit (301) and Emulsification is generated in the emulsifying unit (309) and fed to the emulsion circulation system, or that essentially non-water-enriched diesel fuel is fed to the emulsion circulation system essentially at the same time as a diesel fuel-water emulsion is discharged from the emulsion circulation system.

7. The method according to any one of the preceding claims 5 or 6, characterized in that the diesel fuel-water emulsion derived from the emulsion circulation system is stored and that the stored diesel fuel-water emulsion is fed back into the emulsion circulation system, with preferably the feeding back with a volumetric flow of 2.5% to 15%, preferably 5% to 10%, based on the volumetric consumption of the diesel engine.

8. The method according to any one of the preceding claims, characterized in that a preferably only mechanical emulsification of fuel and emulsifying water is provided in a fluid mechanical mixer (309).

9. The method according to any one of the preceding claims, characterized in that river water, brackish water or sea water is used as emulsifying water, in particular wherein river water, brackish water or sea water is further processed, in particular on-board, in particular desalinated, further in particular according to the reverse osmosis process, wherein , Preferably, the treated river water, brackish water or sea water is stored and / or wherein river water, brackish water or sea water is removed from the environment during operation of the diesel engine (400) and treated.

10. A method for switching or alternating operation of diesel engines (400), in particular for switching ship engines, the diesel engine (400) in diesel fuel operation by injecting a pure diesel fuel into a combustion chamber of the diesel engine (400) or in emulsion operation by injecting a Diesel fuel-water emulsion is operated, in particular as a function of the engine load of the diesel engine (400) and/or the engine power, in particular as a retrofitting and/or conversion method for retrofitting and/or converting a diesel engine system set up for operation with pure diesel fuel switchover operation with diesel fuel or with a diesel fuel-water emulsion, in particular according to one of the preceding method claims,

- wherein the diesel engine (400) has at least one cylinder head (701) with a valve arrangement having at least one intake valve (713), preferably a plurality of intake valves (713, 714) arranged one behind the other in the direction of flow, and wherein water is injected directly into the intake port (710) of the cylinder head (701) is provided.

11. Emulsion circulation system for a diesel engine system, in particular a ship engine system, in particular for retrofitting and/or converting a diesel engine system set up for operation with diesel fuel to switchover operation between diesel fuel operation by injecting a diesel fuel into a combustion chamber of a diesel engine (400) and emulsion operation by injecting a Diesel fuel-water emulsion, in particular for diesel fuel operation or for emulsion operation depending on the engine load of the diesel engine (400) and / or the engine power, with a Metering unit (301) for metering emulsifying water and diesel fuel into the emulsion circulation system and an emulsifying unit (309) for emulsifying emulsifying water and diesel fuel and with a switchover device (405) for load- and/or power-dependent operation of the diesel engine (400) with diesel fuel or with one Diesel fuel-water emulsion, wherein the emulsion circulation system is set up and designed to carry out a method according to one of the preceding claims.

12. Retrofitting and/or conversion method for retrofitting and/or converting a diesel engine system set up for operation with diesel fuel to switchover operation of a diesel engine (400) of the diesel engine system with diesel fuel or with a diesel fuel-water emulsion, in particular for diesel fuel operation or emulsion operation as a function on the engine load of the diesel engine (400) and/or the engine power, in particular for retrofitting and/or converting ship engines, in particular with the method features of one of the preceding claims 1 to 10,

- An injection pump of the diesel engine (400) set up for operation with diesel fuel being modified by a retrofit and/or replacement injection pump (402) with an increased delivery volume of the injection pump (402) and/or with an injection pump set up for operation with diesel fuel Control edge geometry of a pump piston (612) of the injection pump is exchanged.

13. Retrofitting and/or conversion method according to Claim 12, characterized in that a modification of the control rod travel of a control rod provided for rotating the pump piston (612) is provided, with the control rod travel being limited to limit the delivery volume flow in diesel fuel operation and with a larger delivery volume flow in emulsion operation, a larger control rod travel, in particular the maximum control rod travel, is provided or released.

14. Retrofitting and/or conversion method according to one of the preceding claims 12 or 13, wherein an injection pump of the diesel engine (400) which is set up for operation with diesel fuel is replaced by a retrofit and/or replacement injection pump (402) which has a pump piston ( 612) with a wear-reducing coating and/or anti-corrosion coating at least in certain areas, and/or

- An injection valve of the diesel engine (400) that is set up for operation with diesel fuel is replaced by a retrofit and/or replacement injection valve that has a valve needle with a wear-reducing coating and/or anti-corrosion coating that is at least partially visible.

15. Injection pump (402) for a diesel engine (400) of a diesel engine system, with a pump piston (612) with modified control edge geometry according to claim 12 and/or designed to limit the control rod travel according to claim 13.

16. Diesel engine system with a diesel engine (400) and with an emulsion circulation system according to claim 11 and/or with an injection pump (402) according to claim 15 and/or set up and designed for the direct supply of water into an inlet port (711) of a cylinder head (701) the diesel engine (400) of claim 10.