JP4528339B2 - Large two-cycle diesel engine with multiple variable turbochargers - Google Patents

Description

  The present application relates to a large-sized multi-cylinder two-cycle diesel engine including a plurality of variable turbochargers, and specifically to control of a plurality of variable turbochargers.

  Large two-cycle diesel engines are equipped with multiple turbochargers because of their enormous size. Large two-cycle diesel engines are typically huge machines with 5 to 14 cylinders arranged in a row. The scavenging chamber extends along the entire length of the engine, and its length can exceed 30m.

  Theoretically, such an engine may be equipped with a single giant turbocharger, however, that size turbocharger is technically very cumbersome and consequently expensive. Therefore, such large two-cycle diesel engines are typically equipped with two, three, four, and more turbochargers. These turbochargers are evenly distributed along the length of the engine.

  Such known engines are equipped with a conventional turbocharger, that is, such a turbocharger is not variable. The variable turbocharger has the advantage of being able to provide high scavenging pressure at partial load without applying too high pressure at high load. Turbocharger speed decreases with relatively high loads. This feature is similar to exhaust bypass but has higher efficiency. As a result, as the compressor side approaches the surge line, it must be very precisely controlled to avoid surging and stalling. Although suitable control systems for a single variable turbocharger are known, these known control systems are unsuitable for multiple variable turbochargers connected in parallel, specifically the engine Inappropriate for large two-cycle diesel engines.

An object of the present invention is to provide a large two-cycle diesel engine having a plurality of variable turbochargers.
The variable turbocharger can operate with higher efficiency in the runnable operating state of the engine. The optimal setting for a variable turbocharger is generally close to the surge limit (surge line) and when operating near the surge limit, the turbocharger must be accurately controlled to avoid stall .

  The inventor of the present invention has shown that known control systems used in small engines having only a single variable turbocharger do not work for multiple variable turbochargers in a large two-cycle diesel engine for the following reasons: discovered. One reason for this is the fact that multiple variable turbochargers interact with each other, so changing the settings of one variable turbocharger will affect the operation of the other variable turbochargers. Furthermore, the inventors have discovered that the operating state of each variable turbocharger depends on its placement along the engine. Due to the fact that there are significant pressure fluctuations in the scavenging chamber, this arrangement along the engine can significantly affect the operation of the individual variable turbochargers. In large two-cycle diesel engines, such fluctuations are large enough to affect the operation of the turbocharger, and pressure fluctuations cause the corresponding turbocharger speed fluctuations. In general, the low frequency pressure fluctuation is greatest near both ends of the scavenging chamber. In addition, since the present inventor generally provides only one or two of the plurality of turbochargers at the same time, the state of each turbocharger in the plurality of turbochargers is determined by the turbocharger. I found a change. Thus, some of the multiple turbochargers have just been serviced, while others in the multiple turbochargers are not so good, so there is a need for a control system that takes into account such differences. .

  The inventors of the present application have also found that the mechanical tolerance of the variable turbocharger is larger than the mechanical tolerance of the conventional turbocharger. Therefore, the difference between the individual turbochargers in the plurality of variable turbochargers is larger than that of the conventional turbocharger.

  The above object is achieved by combining a plurality of cylinders arranged in a row, a plurality of variable nozzle area turbochargers connected in parallel between an engine exhaust chamber and a scavenging chamber, and a control combined with the plurality of variable turbochargers. A large two-cycle diesel engine having an apparatus, wherein the controller has an outer pressure loop with a pressure controller and an inner speed loop with a speed controller, the pressure controller being a combination of the plurality of turbochargers As achieved by a large two-stroke diesel engine configured to determine a desired total nozzle area, and wherein the speed controller is configured to individually control the speed of each of the plurality of turbochargers.

  By providing an outer control loop that ensures proper pressure in the scavenging chamber and an inner speed control loop for each of the plurality of variable turbochargers, a plurality of two-cycle diesel engine connected in parallel to the scavenging chamber A stable and flexible control system for the variable turbocharger can be obtained.

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

  The speed controller can be configured to compensate for the effects on the other variable turbochargers due to the setting change of one of the variable turbochargers.

  The speed controller can be configured to compensate for differences in exposure to low frequency pressure waves in the scavenging chamber caused by each of the plurality of turbochargers being arranged differently.

  The speed controller can be configured to compensate for the maintenance state of each of the plurality of turbochargers.

  The speed controller can be configured with high speed control to compensate for dynamic differences and low speed control to compensate for permanent or static differences.

  The controller can be configured to operate the turbocharger in a state close to a setting that provides maximum efficiency close to the surge limit.

  The controller uses a signal indicative of the operating state of the engine, such as, for example, inlet temperature, scavenging temperature, exhaust chamber pressure, exhaust chamber temperature, outlet temperature, and / or outlet pressure, for each of the plurality of turbochargers. The distance to the surge limit can be determined as accurately as possible.

  Another object of the present invention is a method for controlling a plurality of variable turbochargers connected in parallel to a scavenging chamber of a large two-stroke diesel engine having a plurality of cylinders arranged in a row. Collectively controlling a desired total nozzle area for the entire variable turbocharger in a scavenging pressure feedback loop; and under the restriction of the desired total nozzle area for the entire plurality of variable turbochargers, the plurality of variable turbochargers Controlling each nozzle area together in a plurality of variable turbocharger speed feedback loops.

  The nozzle area of each of the plurality of turbochargers can be controlled in order to obtain all uniform speeds of the turbocharger.

  A linear secondary regulator can be used to control the nozzle area of each of the plurality of turbochargers.

  Dynamic tolerance with a balanced response in the event of abrupt changes in operating conditions, i.e., rough waves (propellers out on the sea), rapid speed changes (rapid stop and maneuver) and other cases A surge algorithm can be applied. This is particularly relevant if there is a significant difference in turbocharger speed or if one of the turbochargers has a failure.

  Static differences between individual variable turbochargers can be taken into account in controlling the nozzle area of the individual variable turbocharger.

  Another object of the present invention is combined with a plurality of cylinders arranged in a row, a plurality of variable nozzle area turbochargers connected in parallel between an engine exhaust chamber and a scavenging chamber, and the variable turbocharger. A large two-cycle diesel engine comprising a control device, wherein the control device is provided with the speed of each of the plurality of variable turbochargers, and the variable turbocharger has its nozzle area changed And the controller determines the actual nozzle area of the variable turbocharger having the failed actuator based on the speed for all of the variable turbocharger and the position of the non-failed turbocharger. Configured.

  Further objects, features, advantages, and characteristics of the large two-cycle diesel engine, and methods for controlling the large two-cycle diesel engine according to the present invention will become apparent from the detailed description.

Detailed Description of the Preferred Embodiment

  In the following detailed description, the present invention will be described in more detail with reference to exemplary embodiments shown in the drawings.

  In the following detailed description, the present invention will be described using preferred embodiments. 1 to 3 show a crosshead type large turbocharged two-cycle diesel engine 1 having an intake and exhaust system. The engine 1 has a scavenging chamber 2 and an exhaust chamber 3. Each of these air chambers extends along the entire length of the engine. The engine has a plurality of cylinders (generally 5 to 14) arranged in a row. The exhaust valve present in the combustion chamber is indicated by 4. The engine 1 may be used, for example, as a main engine of an ocean-going ship or as a fixed engine that operates a generator of a power plant. The total output of the engine may be in the range of 5,000 to 110,000 + kW, for example. Since the engine 1 generally operates on heavy oil, the engine 1 includes a heavy oil system including a heated heavy oil tank and a heated heavy oil pipe (not shown). These heating elements of the fuel injection system are heated even when the engine is stopped because heavy oil is very sticky at ambient temperature. In addition, a heavy oil system (not shown) includes a recirculation system that allows heavy oil to flow from the components of the heavy oil system during engine shutdown. Recirculation allows the components of the heavy oil system to be kept warm during engine shutdown without the dedicated heating means, and recirculation facilitates degassing of the heavy oil system.

  Scavenging is sent from the scavenging chamber 2 to individual cylinder scavenging ports (not shown). When the exhaust valve 4 is opened, the exhaust flows out of the first exhaust conduit into the exhaust chamber 3 and then passes through the first exhaust conduit 5 to change one of the variable turbochargers 6 Outflow to area turbine 7 (turbocharger with variable nozzle area). Exhaust gas flows from the variable turbocharger 6 through the second exhaust conduit 20. Each of the variable area turbines 7 drives a compressor 9 supplied from the air inlet 10 via the shaft 8. The compressor 9 supplies pressurized scavenging to a scavenging conduit 11 connected to the scavenging chamber 2. As can be seen in FIG. 2, the variable turbochargers 6 are distributed substantially evenly along the length of the engine 1. In this embodiment, there are three variable turbochargers 6, but this number is merely exemplary and there may be several or more variable turbochargers.

  Each variable turbocharger 6 is provided with an actuator, and this actuator controls the nozzle area of the corresponding variable turbocharger 6. The actuators of the plurality of variable turbochargers 6 are connected to the control device 50.

  Intake in conduit 11 passes through a cooler 12 that cools the charge / scavenge, which is about 200 ° C in the compressor, to a level of 36 to 80 ° C. In an embodiment, the cooler 12 can be a washer, in which a large amount of water is injected and evaporated to humidify the supply / scavenging.

  The scavenged air that is believed to be cooled and humidified passes through an auxiliary blower 16 that is driven by an electric motor 17. The electric motor 17 pressurizes the scavenging flow in a low load or partial load state and sends it to the scavenging chamber 2. At higher loads, the turbocharger compressor 9 provides fully pressurized scavenging, and then one or more auxiliary blowers 16 are bypassed via check valves 15.

  Each variable area turbine 7 of the turbocharger 6 is connected to the control device 50 via an actuator. The control device 50 controls the nozzle area of the variable area turbine 7, and the control device 50 receives information related to the operating state of the engine.

  FIG. 4 shows the control device 50 in more detail. The control device 50 includes two control loops. The first control loop is a pressure control loop and is configured to maintain the scavenging pressure at a predetermined control level indicated by “pressure set point” in the figure. The pressure control loop is the outer loop of the two control loops. Further, the control device 50 includes a variable turbocharger speed control loop, and controls the relative speed of each variable turbocharger 6 individually. The variable turbocharger speed control loop is the inner loop. It can only operate within the limits set by the pressure control loop.

  The pressure control loop includes a pressure controller that receives a signal corresponding to the difference between the pressure set point and the measured pressure in the scavenging chamber 2. The pressure controller generates a signal having the total nozzle area of the desired variable turbocharger and is delivered to the variable turbocharger speed controller in the speed loop.

  The variable turbocharger speed controller controls the speed of each variable turbocharger 6 in a feedback control loop. Thus, each variable turbocharger 6 is part of a speed control loop, in which the corresponding variable turbocharger 6 receives individual signals from the variable turbocharger speed controller and The nozzle area of the variable turbocharger 6 is set, and the speed controller receives a signal indicating the speed of each individual variable turbocharger 6.

  The variable turbocharger speed controller receives various engine operating parameters such as inlet temperature, scavenging temperature, exhaust chamber pressure, exhaust chamber temperature, outlet temperature, and outlet pressure, and provides control signals for individual variable turbochargers 6 as appropriate. adjust.

  Each speed control loop includes a PID (proportional / integral / derivative) function to obtain the desired variable turbocharger speed in embodiments that do not include LQR.

  The variable turbocharger speed controller makes the combined variable turbocharger 6 nozzle area equal to the nozzle area of the output signal of the pressure controller that maintains the desired scavenging pressure. However, the nozzle area of each individual variable turbocharger 6 can be varied within the limit that the total area of the combined variable turbocharger 6 is equal to the nozzle area of the output signal to the output signal pressure controller. .

  Changing the setting of one of the variable turbochargers 6 affects the other variable turbochargers 6. For example, as the area of all variable turbochargers 6 decreases, the speed of the variable turbochargers of all turbochargers increases. However, if the nozzle area of one of the variable turbochargers 6 decreases, the speed of a particular variable turbocharger 6 decreases while the speed of the other variable turbocharger 6 increases. Such an action without an appropriate control algorithm can lead to an unstable situation. Thus, the speed controller is configured to take into account the effect of setting changes in one of the turbochargers 6 on the other turbocharger, and also takes into account the effects of simultaneous changes in the role of the turbocharger nozzle area Configured as follows. As used herein, a variable turbocharger speed controller, in an embodiment, includes a linear quadratic regulator (LQR) to provide a controller that offsets the above effects and stabilizes the system. To do.

  Depending on the different objectives, both fast and slow controls are implemented simultaneously. Low speed is applied to compensate for the permanent differences described below. For example, high speed is applied to compensate for a dynamic difference such as a large load change.

  Since engine 1 operates most efficiently when all speeds of variable turbocharger 6 are approximately the same, variable turbocharger speed controllers are typically substantially the same speed for each of variable turbocharger 6. Configured to provide.

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

  One of the exceptions relates to pressure fluctuations in the scavenging chamber 2. In the large scavenging chamber 2, there is a large standing low frequency during engine operation. If the turbocharger 6 is placed just in the “center”, no large pressure fluctuations due to low frequencies are observed. However, in practice, the variable turbocharger 6 must be distributed along the length of the engine, and only some of them can be "centered". The remaining variable turbocharger 6 is exposed to large low-frequency pressure fluctuations, particularly when arranged near both longitudinal ends of the elongated scavenging chamber 2. In such an arrangement, large low frequency pressure fluctuations affect the operating conditions of the corresponding variable turbocharger 6. Therefore, the risk of crossing the surge line and the risk of stalling the relevant turbocharger 6 are increased, so the speed of the relevant turbocharger 6 may fluctuate and can be exposed to such low frequency pressure fluctuations. The turbocharger may not be able to operate in a state close to the surge line.

  Thus, for any turbocharger 6 that is exposed to large pressure swings, the controller 50 includes settings that allow it to operate with considerable margin from the surge line. In general, this means that in practice, the variable turbocharger 6 exposed to large low frequency pressure fluctuations operates at a slightly slower speed than the other turbochargers of the engine 1.

  Another factor is the difference in inlet temperature of the individual variable turbochargers 6. The inlet temperature is sometimes measured directly for each turbocharger 6, but it can be estimated from the temperature sensor in the engine compartment, together with knowledge about the temperature distribution in the engine compartment. Also, such inlet temperature differences are related to the placement of the corresponding variable turbocharger 6 along the length of the engine, and the controller can increase the distance to the surge margin by increasing the turbocharger speed. Configured to increase.

  Another problem is of concern because turbocharger speed fluctuations cause excessive wear. Therefore, the variable variable turbocharger speed should be reduced. These two aspects are forced to control in the opposite direction. However, there is no problem with surging beyond the 75% load, which is considered to be the most severe wear, so the controller achieves the optimal procedure by increasing speed at partial load and decreasing speed at high load. Configured to do.

  Another exception to the principle of operating all turbochargers of the engine at the same speed relates to the maintenance status of the individual variable turbochargers 6. In practice, it is usually not possible to service all turbochargers of engine 1 during a single maintenance. This means that only one or two variable turbochargers 6 are serviced, while the other variable turbochargers 6 are not serviced until the next maintenance. The variable turbocharger 6 in poor maintenance state cannot operate in a state close to a surge line like a turbocharger just maintained. Accordingly, the control device 50 is provided with a maintenance state relating to the individual turbocharger 6, and operates the turbocharger just maintained in a state closer to the surge line than the turbocharger 6 not maintained. In general, this means that, in practical terms, a newly-developed variable turbocharger 6 operates at a slightly higher speed than an unmaintained turbocharger 6.

  Furthermore, because the structural tolerances of variable turbochargers are relatively large, their characteristics may vary depending on the turbocharger, even for the same type of turbocharger. The controller compensates for these differences. Although the mechanical tolerances of the variable turbocharger 6 typically result in turbocharger speed deviations, the effects of the tolerances are offset because the controller is configured to balance the speed of the variable turbocharger.

  If the speed of the individual variable turbochargers 6 is significantly different from each other, or if one of the variable turbochargers 6 fails, a dynamic anti-surge algorithm with a balanced response is applied.

  The control device 50 comprises a fault handling, monitoring and diagnostic module. The module includes both an optimal response for difficult operating conditions (sudden stops, rough waves, etc.) and an optimal response in the event of a variable turbocharger actuator failure.

  In the event of an actuator failure in one of the variable turbochargers 6, its nozzle position is estimated by the speed of all other variable turbochargers and the position of the other variable turbocharger 6. Therefore, the control device 50 can grasp the sum of the nozzle areas of all the combined variable turbochargers 6 and determine an appropriate position of the variable turbocharger 6 without any defects.

  In an embodiment (not shown), one or more of the turbochargers 6 are non-variable, but other turbocharger variable types of the engine. In such a system, the control device recognizes the nozzle area of the non-variable turbocharger and adjusts the variable area of the remaining variable turbochargers as appropriate.

  In an embodiment, the system has two turbochargers. One is variable and the other is conventional. A variable turbocharger is generally the larger of the two. At low loads, the variable turbocharger is closed as much as possible (minimum nozzle area) to increase the pressure in the exhaust chamber. This increases the amount of energy supplied to the turbocharger (mainly the smaller non-variable turbocharger) and increases the scavenging pressure. Of course, the variable turbocharger must be maintained to the right of the surge limit. At high loads, avoiding excessive speed is important for small (conventional) turbochargers in terms of excessive speed and wear.

  The above is improved by increasing the nozzle range over the existing variable turbocharger solution.

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

  In another aspect, when using multiple conventional turbochargers, these turbochargers must be the same and therefore need to be oversized. This excess dimensional problem can be avoided by combining large and small turbochargers, but can only be achieved if at least one of the combined size turbochargers is variable.

  The various aspects relating to the above can be used alone or in various combinations. The teachings of this application are preferably implemented by a combination of hardware and software, but can also be implemented in hardware. The teachings of the present application may also be embodied as computer readable code on a computer readable medium.

  The teachings of the present application have many advantages. Various embodiments or implementations can provide one or more of the following advantages. Note that this is not a comprehensive description and there are other advantages not described herein. One advantage of the teachings of the present application is to provide stable control of multiple variable turbochargers in a large two-cycle diesel engine. Another advantage of the teachings of the present application is to provide control of multiple variable turbochargers in a large two-stroke diesel engine that can account for static differences between individual turbochargers. Yet another advantage of the teachings of the present application provides for control of emergency and / or difficult operating conditions of multiple variable turbochargers of a large two-cycle diesel engine. A further advantage of the present invention is that it reduces wear as well as providing optimum engine performance and emissions reduction by making the variable turbocharger speed substantially uniform. Another advantage of the present invention is to provide a control system that reduces the risk of stalling. A further advantage of the present invention is that fault handling is optimized. Another advantage of the present invention is that local differences in turbocharger operating conditions can be offset. Another advantage of the present invention is that it allows optimal utilization of different sized variable turbochargers. A further advantage of the present invention is that it allows cost savings for large engine variable turbochargers by providing control of a large two-stroke diesel engine through a combination of variable and non-variable turbochargers.

  Although the teachings of the present application have been described in detail for purposes of illustration, such details are not intended solely for that purpose, and can be varied by those skilled in the art without departing from the scope of the teachings of the present application. Please understand that.

  The term “comprising”, used in the claims, does not exclude other elements or steps. The singular terms used in the claims do not exclude the plural. A single processor or other unit may fulfill the functions of several means recited in the claims.

1 is a front view of a large two-cycle diesel engine according to an embodiment of the present invention. FIG. 2 is a side view of the two-cycle diesel engine of FIG. 2 is a schematic diagram of the intake and exhaust system of the engine of FIG. FIG. 2 is a block diagram showing a control device for a turbocharger of the engine of FIG.

Claims (14)

A large size having a plurality of cylinders arranged in a row, a plurality of variable nozzle area turbochargers connected in parallel between the exhaust chamber and the scavenging chamber of the engine, and a control device combined with the plurality of variable turbochargers A two-cycle diesel engine,
The controller has an outer pressure loop with a pressure controller and an inner speed loop with a speed controller;
The pressure controller is configured to determine a desired total nozzle area as a combination of the plurality of turbochargers;
The speed controller is configured to individually control the speed of each of the plurality of turbochargers;
Large two-cycle diesel engine.   The large two-stroke diesel engine of claim 1, wherein the speed controller is configured to provide a substantially equal speed for each of the plurality of variable turbochargers.   The large two-stroke diesel engine of claim 1, wherein the speed controller is configured to compensate for an effect on other variable turbochargers due to a setting change of one of the plurality of variable turbochargers.   4. The speed controller of claim 1, wherein the speed controller is configured to compensate for differences in exposure to low frequency pressure waves in the scavenging chamber caused by each of the plurality of turbochargers being arranged differently. A large two-cycle diesel engine according to any one of the above.   The large-sized two-cycle diesel engine according to any one of claims 1 to 4, wherein the speed controller is configured to compensate for a maintenance state of each of the plurality of turbochargers.   The large speed two-stroke diesel engine according to any one of claims 1 to 5, wherein the speed controller includes a high speed control for compensating for a dynamic difference and a low speed control for compensating for a permanent or static difference. The large-sized two-cycle diesel engine according to any one of claims 1 to 6 , wherein the control device is configured to operate the turbocharger in a state close to a setting at which the maximum efficiency is close to a surge limit.   The controller uses the signals indicating the operating state of the engine, such as an inlet temperature, a scavenging temperature, an exhaust chamber pressure, an exhaust chamber temperature, an outlet temperature, and / or an outlet pressure, for example. The large two-stroke diesel engine according to claim 7, wherein the distance to each of the surge limits can be determined as accurately as possible. A method for controlling a plurality of variable turbochargers connected in parallel to a scavenging chamber of a large two-cycle diesel engine having a plurality of cylinders in a row,
Collectively controlling a desired total nozzle area for the entire plurality of variable turbochargers in a scavenging pressure feedback loop;
Controlling the nozzle area of each of the plurality of variable turbochargers collectively in a plurality of variable turbocharger speed feedback loops, under a desired total nozzle area limitation on the entirety of the plurality of variable turbochargers;
Including methods.   The method of claim 9, wherein the nozzle area of each of the plurality of turbochargers is controlled for the purpose of obtaining all uniform speeds of the turbocharger.   The method of claim 10, wherein a linear secondary regulator is used to control the nozzle area of each of the plurality of turbochargers.   12. A dynamic surge tolerant algorithm with a balanced response is applied if the speeds of the individual variable turbochargers are significantly different, or if one of the variable turbochargers fails. The method described.   The method of claim 12, wherein static differences between individual variable turbochargers are considered in controlling the nozzle area of the individual variable turbochargers.   Large-size 2 comprising a plurality of cylinders arranged in a row, a plurality of variable nozzle area turbochargers connected in parallel between the exhaust chamber and the scavenging chamber of the engine, and a control device combined with the variable turbocharger In the cycle diesel engine, the control device is provided with a speed of each of the plurality of variable turbochargers, and the variable turbocharger is provided with an actuator that changes a nozzle area thereof. A large two-cycle diesel engine configured to determine the actual nozzle area of a variable turbocharger having a failed actuator based on the speed for all of the variable turbochargers and the position of a non-failed turbocharger.

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