KR20090119655A - Large 2-stroke diesel engine with multiple variable turbochargers - Google Patents

Abstract

PURPOSE: A two-stroke diesel engine with a multi variable turbo charger is provided to reduce wear by reducing exhausted objects. CONSTITUTION: A two-stroke diesel engine with a multi variable turbo charger comprises a scavenging air receiver(2), a controller, an exhaust valve(4) and a variable region turbine. A variable nozzle region turbo charger is connected between the scavenging air receiver and exhaust gas receiver of an engine. The controller is connected to the variable turbo charger. The controller includes an outer pressure loop with a pressure controller and an inner speed loop with a speed controller. The pressure controller determines the desired whole nozzle region of combined turbo chargers. The speed controller controls the speed of discrete turbo chargers. The speed controller gains the speed from the discrete variable turbo charger.

Description

Large 2-stroke diesel engine with multiple variable turbochargers

The present invention relates to the control of large multi-cylinder two-stroke diesel engines, in particular a plurality of variable turbochargers, with a plurality of variable turbochargers.

Due to the surprising size of diesel engines, large two-stroke diesel engines have been provided with multiple turbochargers. Large two-stroke diesel engines are large machines with generally five to fourteen cylinders arranged in a line. A scavenging air receiver extends along the entire length of the engine and may extend beyond 30 meters.

In theory, these engines are provided with one large turbocharger. However, manufacturing turbochargers of this size is technically very difficult and consequently very expensive. Thus, these large two-stroke diesel engines are provided with two, three, four or more turbochargers. These turbochargers are evenly distributed along the length of the engine.

These engines are provided with a general turbocharger, which is not a variable type. Variable turbochargers have the advantage of providing high scavenging air pressure at partial loads without providing high pressure at high loads. Turbocharger speed is reduced relatively at high loads. This feature is similar to exhaust gas bypass but with high efficiency. As a result, the compressor side moves close to the surge line, which must be controlled very precisely to avoid surge and stalling. Suitable control systems for a single variable turbocharger are known, but such control systems are not suitable for many variable turbochargers connected in parallel, in particular when the engine is a large two-stroke diesel engine.

It is an object of the present invention to provide a large two-stroke diesel engine with a number of variable turbochargers.

The variable turbocharger can be operated with high efficiency in variable operating conditions of the engine. The optimal setting for the variable turbocharger is adjacent to the surge limit (surge line), and when operating close to the surge limit, the turbocharger must be precisely controlled to avoid stall.

The inventors of the present invention have recognized that known control systems for small engines having only a single variable turbocharger do not function for many variable turbochargers on large two-stroke diesel engines for the following reasons. One of the reasons for this is that multiple variable turbochargers affect each other so that a change in configuration for one variable turbocharger affects the operation of another variable turbocharger. In addition, the inventors will find that the operating conditions for each variable turbocharger will depend on the placement of the engine. This arrangement along the engine has a significant impact on the operation of the individual variable turbocharger due to the fact that there is a substantial pressure wave inside the scavenging air receiver. In large two-stroke diesel engines, they are large enough to affect the operation of these pulsating turbochargers; Due to pressure fluctuations, the phenomena also appear in the speed of the associated turbocharger. In general, low frequency pressure waves are most harmful near the end of the scavenging receiver. The inventors have recognized that the conditions of the individual turbochargers of the plurality of turbochargers are different for each turbocharger because only one or two of the multiple turbochargers can be overhauled at the same time. Thus, some of the many turbochargers can be serviced in recent years, while others of the many turbochargers are in a better condition, and there is a need for a control system that accounts for these differences.

The inventors have found that the mechanical tolerances are greater for variable turbochargers than for conventional turbochargers. Thus, it has been recognized that the difference between individual turbochargers in multiple turbochargers of the variable type is greater than that of a typical turbocharger.

It is an object of the present invention to provide a plurality of cylinders arranged in a row, a plurality of variable nozzle area turbochargers connected side by side between the scavenging air receiver and the exhaust gas receiver of the engine, and a controller connected to the variable turbocharger. A large two-stroke diesel engine is provided, the controller comprising an outer pressure loop including a pressure controller and an inner speed loop with a speed controller, the pressure controller determining the desired total nozzle area of the combined turbocharger. And the speed controller is configured to control the speed of the individual turbocharger.

By providing an external control loop to ensure accurate pressure in the scavenging air receiver and an internal separate speed control loop for each variable turbocharger, for multiple variable turbochargers connected side by side to large two-stroke diesel engines. A stable and flexible control system is obtained.

Preferably, the speed controller is configured to obtain substantially the same speed for each individual variable turbocharger.

The speed controller may be configured to compensate for other variable turbochargers on the influence of the changed setting of one of the variable turbochargers.

The speed controller may be configured to compensate for differences exposed to low-frequency pressure wavelengths in the scavenging air receiver caused by different arrangements of the individual turbochargers.

The speed controller can be configured to compensate for the maintenance state of the individual turbocharger.

The speed controller is provided with a low speed controller for compensating for a permanent or static difference and a high speed controller for compensating for a dynamic difference.

The controller is configured to operate the turbocharger close to what is set at the highest efficiency near the surge limit.

The controller uses indication signals for the operating state of the engine, for example inlet temperature, scavenging air temperature, exhaust receiver pressure, exhaust receiver temperature, outlet temperature and / or outlet pressure, so that the individual turbocharger You will determine the distance as precisely as possible.

Another object of the present invention is to provide a method of controlling a plurality of variable turbochargers connected side by side to a scavenging air receiver of a large two-stroke diesel engine having a plurality of cylinders arranged in a line, the scavenging air pressure Controlling the entire desired nozzle area of all variable turbochargers as in a feedback loop, and individually varying within the constraints of the entire desired nozzle area of the variable turbocharger as in multiple variable turbocharger speed feedback loops. Controlling the nozzle area of the turbocharger.

The nozzle area of the individual turbocharger can be controlled for the purpose of obtaining a uniform speed for all turbochargers.

A linear secondary regulator can be used to control the nozzle area of the individual turbocharger.

Surge-resistant dynamic algorithms with balanced response can be applied when sudden changes in operating conditions occur, i.e. in rough seas (propellers float above the surface), in case of rapid speed changes (impact stops and steering) and elsewhere. Can be. This is particularly relevant if there is a significant change in turbocharger speed or if one of the turbochargers is broken.

Static differences between the individual variable turbochargers are considered in controlling the nozzle area of the variable variable turbochargers.

Another object of the present invention is a large size comprising a plurality of variable nozzle area turbochargers connected side by side between a plurality of cylinders arranged in a row, the exhaust gas receiver and the scavenging air receiver of the engine, and a controller connected to the variable turbocharger. In providing a two-stroke diesel engine, the controller is provided with the speed of each variable turbocharger, and the variable turbocharger is provided with an actuator for changing its nozzle area, and the controller is provided with all variable turbochargers. And to determine the actual nozzle area of the variable turbocharger with the failed actuator based on the speed of the engine and the position of the failed turbocharger.

As features, advantages, characteristics, and additional objects of the large two-stroke diesel engine, the method for controlling the large two-stroke diesel engine according to the present invention will become apparent from the following description.

The teachings herein have various advantages. Other embodiments or implementations involve one or more of the following advantages. This is not an exhaustive list, but may be another advantage not described here. One advantage of the teachings herein is that the present invention provides for reliable control of many variable turbochargers in large two-stroke diesel engines. Another advantage of the teachings herein is that the present invention can control a number of variable turbochargers in large two-stroke diesel engines that can take into account static differences between individual turbochargers. Another advantage of the teachings herein is that it enables control of emergency and / or difficult operating conditions of many variable turbochargers of large two-stroke diesel engines. A further advantage of the present application is that it can provide near uniform speed of a variable turbocharger with reduced emissions and reduced wear while providing optimum engine performance. Another advantage of the present application is that it can provide a control system that can reduce the risk of stall. As a further advantage of the present application, the breakage operation is optimized. As an additional advantage of the present application, regional differences in turbocharger operating conditions can be counteracted. As an additional advantage of the present application, variable turbochargers of different sizes can be optimally used. As an additional advantage of the present application, it is possible to control a large two-stroke diesel engine in which a variable and non-variable turbocharger is mixed and reduce the cost for a variable turbocharger in a large engine.

In the description of the invention, the invention is described with reference to the exemplary embodiments shown in the drawings.

In the following description, the invention is illustrated by the preferred examples. 1-3 show a large turbocharged two-stroke diesel engine of the crosshead type with an intake and exhaust system. The engine 1 has a scavenging air receiver 2 and an exhaust gas receiver 3. Each of these receivers extends along the entire length of the engine. The engine has a plurality of cylinders (especially 5 to 14) arranged in a row. The exhaust valve belonging to the combustion chamber is represented by four. The engine 1 can be used, for example, as a stationary engine operating as a main engine of a ship sailing in the ocean or as a generator of a power station. The overall power of the engine is, for example, in the range of 5,000 to 110,000+ kW. Since the engine 1 is to be operated on heavy fuel oil, it has a heavy fuel oil system having a heated heavy fuel oil tank and a heated heavy fuel oil tube (not shown). These heated elements of the fuel injection system are heated at engine shutdown because heavy fuel oil is extremely viscous in the atmosphere. In addition, a heavy fuel oil system (not shown) is provided with a circulation system that allows heavy fuel oil to flow through the components of the heavy fuel oil system upon engine shutdown. The circulation system allows components of the heavy fuel oil system that do not have their own dedicated heating means to remain warm at engine shutdown, and this circulation promotes the de-aeration of the heavy fuel oil system. do.

The scavenging air passes from the scavenging air receiver 2 to the scavenging air port (not shown) of the individual cylinder. When the exhaust barb 4 is opened, the exhaust gas is directed to the exhaust receiver 3 through the first exhaust conduit and the variable region of the plurality of variable turbochargers 6 through the first exhaust conduit 5. It is directed to a turbine 7 (a turbocharger with a variable nozzle area) from which the exhaust gas flows through the second exhaust conduit 20. Each variable region turbine 7 drives a compressor 9, which is supplied through an air inlet 10, via a shaft 8. The compressor 9 delivers the compressed scavenging air to the scavenging air conduit 11 extending to the scavenging air receiver 2. As shown in FIG. 2, the variable turbocharger 6 is distributed almost uniformly in the longitudinal direction of the engine 1. In this embodiment, there are three variable turbochargers 6, the number of which is exemplary only, and more or smaller variable turbochargers may be present.

Each variable turbocharger 6 is provided with an actuator that controls the nozzle area of the associated variable turbocharger 6. Each actuator of the plurality of variable turbochargers is connected to a controller 50.

Intake air in the conduit 11 passes through a cooling unit for cooling charging / scavenging air leaving the compressor at a level of about 200 ° C. to 36 to 80 ° C. In one embodiment, the cooling unit 12 is present in the scrubber where a large amount of water is injected and evaporated to humidify the charging / scavenging air.

The scavenging air, which is likely to be cooled and humidified, passes through the auxiliary blower 16 driven by the electric motor 17 which presses the scavenging air under low or partly load conditions to the scavenging air receiver 2. At higher loads, the turbocharger compressor 9 carries sufficiently compressed scavenged air and the auxiliary blower 16 is bypassed through the non-return valve 15.

The variable area turbine 7 of each turbocharger 6 is connected to the controller 50 via an actuator. The controller 50 controls the nozzle area of the variable area turbine 7 and the controller 50 receives information about engine operating conditions.

4 shows the controller 50 in more detail. The controller 50 has two control loops. The first control loop is a pressure control loop configured to maintain the scavenged air pressure at a predetermined constant level, indicated as a "pressure set point" in the figure. The pressure control loop is the outer loop of the two control loops. The controller 50 also includes a variable turbocharger speed control loop that individually controls the relative speed of each variable turbocharger 6. The variable turbocharger speed control loop is an inner loop, ie it operates only within the limits set by the pressure control loop.

The pressure control loop comprises a pressure controller that receives a signal corresponding to the difference between the measured pressure at the scavenging air receiver 2 and the pressure set point. The pressure controller generates a signal with the desired totally variable turbocharger nozzle area passed to the variable turbocharger speed controller in the speed loop.

The variable turbocharger speed controller individually controls the speed of each variable turbocharger 6 in a feedback control loop. Thus, each variable turbocharger 6 receives a separate signal from the variable turbocharger speed controller for the setting of the nozzle area of the respective variable turbocharger with which the associated variable turbocharger 6 is associated and the speed controller Is part of a speed control loop that receives a signal indicative of the speed of the individual variable turbocharger 6.

The variable turbocharger speed controller receives various engine operating parameters such as inlet temperature, scavenged air temperature, exhaust receiver pressure, exhaust receiver temperature, outlet temperature and outlet pressure and accordingly controls each individual turbocharger 6. Adjust the signal.

In one embodiment, the individual speed control loop includes a PID (proportional / integral / differential) function rather than an LQR function to achieve the desired variable turbocharger speed.

Due to the variable turbocharger speed controller, the nozzle area of the combined variable turbocharger 6 is equal to that of the output signal of the pressure controller in order to maintain the desired desired air pressure. However, the nozzle area of each turbocharger 6 will vary within the constraint that the entire area of the coupled variable turbocharger 6 becomes equal to that of the output signal to the pressure controller.

The change in the setting of one of the variable turbochargers 6 will affect the other variable turbocharger 6. For example, the area of all turbochargers 6 is reduced and the variable turbocharger speed for all turbochargers 6 is increased. However, if only one of the variable turbochargers 6 is reduced, the nozzle area speed of that particular variable turbocharger 6 is reduced while the speed of the other variable turbocharger 6 is increased. Without the proper control algorithm, this effect would be unstable. Thus, the speed controller is configured to take into account that the change in the setting of one of the turbochargers 6 appears in the other turbocharger and to take into account the simultaneous change of the nozzle area in the turbocharger. In one embodiment, the variable turbocharger speed controller includes a linear quadratic regulator (LQR) that meets the aforementioned effects and provides a controller to stabilize the system.

Fast and slow control is done simultaneously for different purposes. The compensation for the permanent difference, which will be explained below, applies to the slow. Compensation for dynamic differences, eg significant load changes, applies to fast.

The variable turbocharger speed controller is generally configured to achieve substantially the same speed for each variable turbocharger 6 because the engine 1 has a speed at which all the variable turbochargers 6 are about the same speed. This is because it works most effectively when you have it.

However, there are some exceptions to the principle of operation of all variable turbochargers 6 at the same speed.

One exception, however, relates to the pressure fluctuations of the scavenging air receiver 2. In the large scavenging receiver 2, in operation, there is a large low frequency wavelength. If the turbocharger 6 is in the “eye” position, no experience is experienced with the large pressure wavelengths exhibited by the low frequency wavelengths. In practice, however, the variable turbocharger 6 must be arranged uniformly in the longitudinal direction of the engine and only some of them can be precisely placed in the "eye" position. The remaining turbochargers 6 are exposed to large low frequency pressure waves, especially when they are arranged near the longitudinal end of the extended scavenging air receiver 2. In this arrangement, the large low frequency pressure wave affects the operating conditions of the associated variable turbocharger 6. As a result, the speed of the turbocharger 6 becomes pulsing and it becomes impossible to operate a variable turbocharger exposed to this low frequency pressure wave adjacent to the surge line, because it is beyond the surge line and the associated turbocharger ( 6) The risk of stalling is too high.

Thus, the controller 50 is provided with a setting to operate any turbocharger 6 that is exposed to a large pressure swing with a large margin from the frost line. In general, this means that a variable turbocharger exposed to a large low frequency pressure wave operates at a slightly lower speed than other turbochargers of the engine 1.

Another factor is the difference in inlet temperature for the individual variable turbocharger 6. The inlet temperature is measured directly at each turbocharger 6 but can be estimated from a temperature sensor in the engine room combined with information about the temperature distribution of the engine room. This difference in inlet temperature may relate to the placement of the associated variable turbocharger 6 along the length of the engine, the controller being configured to increase the distance to the surge margin by increasing the turbocharger speed.

Another issue is involved, as the speed of the turbocharger speed results in additional wear, so that the speed of the tunable variable turbocharger is reduced. These two features drive the controller in opposite directions. However, there is no problem in surging where the wear condition exceeds about 75%, which is the worst, so that the controller is configured to achieve an optimal process while reducing speed at high loads and increasing speed at partial loads.

Another exception to the principle of operating all turbochargers of the engine at the same speed relates to the holding state of the individual variable turbocharger 6. In fact, it is impossible to service all the turbochargers of the engine 1 during one hold. This means that only one or two of the plurality of variable turbochargers 6 can wait for the next maintainer. In a better holding state the variable turbocharger 6 cannot be operated adjacent to the frost line as the newly maintained turbocharger 6. Thus, the controller 50 is provided with a maintenance state of the individual turbocharger 6 and operates the newly maintained turbocharger adjacent to the surge line than the uncharged turbocharger 6. In general, this means that a recently serviced turbocharger 6 will operate at a slightly higher speed than a turbocharger that has not been serviced recently.

In addition, the structural tolerances for variable turbochargers are slightly higher, so their characteristics are different for each turbocharger even if they are of the same type. The controller compensates for this difference. The result of mechanical tolerances in the variable turbocharger 6 results in an error in turbocharger speed, because the controller is configured to balance the speed of the variable turbocharger where the effects of the tolerances are met. .

Dynamic algorithms to prevent surges with balanced responses are applied when the speeds of the individual variable turbochargers 6 are significantly different from each other or one of the variable turbochargers 6 is broken.

The controller 50 is provided with a breakage manipulation, supervision, and diagnostic module. Such modules include both optimum response in threatening operational states (collision stops, storms, etc.) and optimal response in the event of failure of the variable turbocharger actuator.

In case of failure of the actuator of one of the variable turbochargers 6, the nozzle position is predicted by the speed of all other variable turbochargers and the position of the other turbochargers. Thus, the controller 50 knows the sum of the nozzle areas of all the variable turbochargers 6 combined and determines the proper position of the variable turbocharger 6 without defects.

In one embodiment, not shown, one or more of the turbochargers 6 are non-variable, while the other turbochargers of the engine are variable. In such a system, the controller knows the nozzle area of the non-variable turbochargers and adjusts the variable area of the remaining variable turbochargers.

In one embodiment, the system has two turbochargers. One is variable and the other is general. Variable turbochargers are generally one of two large. At light loads, the variable turbocharger is as close as possible to increase the exhaust gas receiver pressure (minimum nozzle area). This results in an increase in the amount of energy delivered to the turbocharger (first of all in a non-variable turbocharger), and the scavenged air pressure increases. The variable turbocharger is kept to the right of the surge limit. At high loads, it aims to avoid too high speed in a small (typical) turbocharger for speed and wear.

The foregoing represents an improvement over the nozzle range compared to existing variable turbocharger solutions.

The same principle can be used for systems with more than two turbochargers.

Another feature is the need to increase the dimensions when using multiple turbochargers of the general type, since they must be identical. This problem of oversizing is solved by mixing a large turbocharger and a small turbocharger, while on the one hand it is only achieved when at least one of these mixed-sized turbochargers is variable.

Various features of the foregoing may be used alone or in various combinations thereof. The teachings herein are preferably done by combining hardware and software, but can be done in hardware. The teachings herein may be embodied as computer readable code on a computer reading medium.

Although the teachings herein have been described for illustrative purposes, these detailed descriptions are for illustrative purposes, and various modifications are possible by one of ordinary skill in the art without departing from the scope of the teachings herein.

The term "comprises" as used in the claims, does not exclude other components or steps. In the claims, the singular elements do not exclude the plural elements. A single processor or other unit satisfies the functionality of multiple means as set forth in the claims.

1 is a front view of a large two-stroke diesel engine according to an embodiment of the present invention.

FIG. 2 is a side view of the two-stroke diesel engine of FIG. 1. FIG.

3 is a diagram of an intake and exhaust system of the engine of FIG. 1.

4 is a block diagram illustrating a controller for the turbocharger of the engine of FIG. 1.

Claims (14)

In large two-stroke diesel engines with multiple cylinders arranged in a row, a plurality of variable nozzle area turbochargers are connected side by side between the scavenging air receiver and the exhaust gas receiver of the engine, and a controller is connected to the variable turbocharger. Connected, The controller includes an outer pressure loop with a pressure controller and an inner speed loop with a speed controller, the pressure controller being configured to determine a desired total nozzle area of the combined turbochargers, the speed controller being each individual A large two-stroke diesel engine configured to control the speed of turbochargers. The method of claim 1, And the speed controller is configured to obtain substantially the same speed for the individual variable turbocharger. The method of claim 1, The speed controller is configured to compensate for the effect of a change in the setting of one of the variable turbochargers to the other variable turbocharger. The method according to any one of claims 1 to 3, The speed controller is configured to compensate for differences exposed to low frequency pressure wavelengths in the scavenging air receiver caused by different arrangements of individual turbochargers. The method according to any one of claims 1 to 4, The speed controller is configured to compensate for the maintenance of the individual turbochargers. The method according to any one of claims 1 to 5, And said speed controller is provided with high speed control for compensation for dynamic differences and low speed control for compensation for permanent or static differences. The method according to any one of claims 1 to 6, And the controller is configured to operate the turbocharger close to the set point with maximum efficiency adjacent to the surge limit. The method of claim 7, wherein The controller is configured to measure the distance of the individual turbochargers as accurately as possible to the surge limit, for example engine operating conditions such as inlet temperature, scavenging air temperature, exhaust receiver pressure, exhaust receiver temperature, exhaust temperature and / or outlet pressure. Large two-stroke diesel engine, characterized in that using a signal indicating. A method of controlling a plurality of variable turbochargers connected side by side to a scavenging air receiver of a large two-stroke diesel engine with multiple cylinders arranged in a row, The method, Controlling the desired total nozzle area of all variable turbochargers with a scavenging air pressure feedback loop; Controlling the nozzle area of the individual variable turbochargers within the constraints of the desired total nozzle area of the variable turbocharger with a plurality of variable turbocharger speed feedback loops. The method of claim 9, Wherein the nozzle area of the individual turbocharger is controlled to obtain a uniform speed for all turbochargers. The method of claim 10, A linear secondary regulator is used to control the nozzle area of the individual turbochargers. The method of claim 11, Dynamic algorithms to prevent surges with balanced response control multiple variable turbochargers, which are applied when the speeds of individual variable turbochargers differ significantly or when one of the variable turbochargers is broken. How to. The method of claim 12, The static difference between the individual variable turbochargers is considered by the control of the nozzle area of the individual variable turbochargers. In large two-stroke diesel engines with multiple cylinders arranged in a row, a plurality of variable nozzle area turbochargers are connected side by side between the exhaust gas receiver and the scavenging air receiver of the engine, and a controller is connected to the variable turbocharger. The controller is provided with a speed of each variable turbocharger, and the variable turbocharger is provided with an actuator to vary the nozzle area, the controller being capable of speeds of all variable turbochargers and the unbroken turbocharger of the turbocharger. A large two-stroke diesel engine configured to determine the actual nozzle area of a variable turbocharger with a broken actuator based on location.

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