Keiichi Shiraishi

Improvement of the transient response of power turbine generators for energy savings in ship plants

The purpose of this paper is to present the transient response of the power turbine generator (PTG) system. A generating system has been developed that is driven by a power turbine using the exhaust gas from a diesel marine engine, this PTG system is expected to deliver energy savings. The power source should be stable in terms of both frequency and voltage for high quality. However, it is difficult to control the frequency for the PTG system by a governing, since the power turbine uses gas that must be kept constant, as well as the issue of soot. Accordingly, simulation has been employed to improve the PTG system composition and control. As a result, the overshoot shows up to 27% improvement. In subsequent verification of the simulation results conducted by observing a prototype plant, the overshoot of frequency realized the same peak. This peak value sufficiently satisfies operational requirements.

A naew control method for power turbine generators using an accurate ship plant system model

The purpose of this paper is to present a new control method for a power turbine generator (PTG) system using an accurate ship plant system model that ascertains startup characteristics. The PTG system is a waste heat recovery type generation system making use of exhaust gas from the main shipboard diesel engines. However, with the PTG systems, control during startup is not entirely clear. Startup characteristics from power turbine startup through synchronization to the system bus are ascertained using an accurate simulation model, and startup sequence control is clarified for a combination of gas valve operation and load bank. A prototype constructed on the basis of the simulation. As a result, in the startup process, so as to limit speed overshooting that is 0.83 p. u. at 100% output from main diesel engine as the severest condition. The synchronization to the system bus is attained, and highly satisfactory results are achieved.

Electro-Assist Turbo for Marine Turbocharged Diesel Engines

Turbocharged diesel engines are widely used in the marine industry and have a significant impact on global CO2 and NOx emissions. Turbochargers are an integral component of any diesel engine and they play a critical role in their performance. Mitsubishi Heavy Industries (MHI) and Calnetix Technologies have developed a unique technology called the “Electro-Assist Turbo” (EAT). The EAT unit consists of a specially designed high speed permanent magnet motor directly mounted to the turbocharger rotating assembly. The high speed motor applies torque to the turbocharger rotor enabling it maintain or vary rotor speed at low engine exhaust flow rates in order to supply sufficient charge air to maximize engine performance. Turbocharged diesel engines suffer from inherent deficiencies at low engine speeds; there is not enough energy in the exhaust to produce an optimum and readily available level of boost for the engine intake air system at off-design points. This technology proves even more important as the majority of large marine vessels are now operating in a “slow steaming” part throttle mode. To date the majority of marine diesel engines use auxiliary air blowers (AAB) to supply additional air to the engine intake during off design point operation. These AABs are inefficient and not intended nor designed to be used in constant operation. The EAT unit can provide a higher discharge pressure at the same electrical power consumption as an AAB. This more efficient design with higher discharge pressure further improves fuel efficiency and eliminates the need to run an external piece of machinery during operation, thus lowering maintenance costs.This paper will provide an overview of the design, integration and initial testing of the 100kW Electro-Assist Turbo into a Mitsubishi Exhaust-gas Turbocharger (MET)-83 marine diesel turbocharger. In addition this paper will go over the custom designed aerodynamic motor housing structure that holds the non-rotating components without penalizing performance of the turbocharger, special software developed for the variable frequency drive system that enables the flexible operation of the high speed motor, and features of the high speed permanent magnet motor that allows for operation without any active cooling. Also, this paper will provide and discuss the initial test results of the EAT integrated into the MET-83 turbocharger along with engine testing results provided by MHI. Low cost designs will be discussed that enable turbochargers currently in operation to be retrofitted and the further improvements taking place to commercialize.Copyright

Development of new turbocharger technologies for energy efficiency and low emissions

This report presents the MET-MB turbocharger, the latest model high-pressure-ratio, high-efficiency turbocharger from Mitsubishi Heavy Industries, developed to meet NOx TierII regulations. This report also describes the development a new type of variable nozzle turbocharger designed to improve low-speed performance in response to recent requirements for greater main engine fuel efficiency, as well as a hybrid turbocharger for greater fuel efficiency at high loads.

An improved model and its applied adaptive control for power turbine generator

Purpose – The purpose of this paper is to present an improved model and its applied adaptive controller for a waste heat recovery generation system using a power turbine generator (PTG) with an accurate model on shipboard that is employed by an identification method on the basis of an overall system model.Design/methodology/approach – The PTG system has been developed as a waste heat recovery type generation system making use of exhaust gas from the main shipboard diesel engines. Conventionally, control of a plant is exercised using the proportional‐integral‐derivative (PID)‐based controller. The PID controller, however, is difficult to keep in place because of fouling conditions and variations across time. Thus, the load bank controller is proposed using a PID‐based controller. The controller should take into account both the fouling conditions and variations across time because the exhaust gas contains considerable amounts of ash and soot. Hence, an accurate model needs to improve the dynamic characteri...

A new approach of model reference adaptive controller for distributed power supply using power turbine generator

The purpose of this paper is to present a new approach of model reference adaptive controller for distributed power supply using a power turbine generator (PTG) with an accurate model on shipboard that is employed by an identification method on the basis of an overall system model. The proposed controller is evaluated by comparing the conventional controller. As a result, the limit speed overshooting is improved more than 25%. Hence, it is confirmed that the proposed model has excellent property.

A new control method in startup progress for power turbine generators as waste heat recovery system using an overall shipboard system model

Purpose – The purpose of this paper is to present a new control method for a power turbine generator (PTG) as a waste heat recovery system using an overall shipboard system model that ascertains startup characteristics.Design/methodology/approach – The PTG system is a waste heat recovery‐type generation system making use of exhaust gas from the main shipboard diesel engines. With the PTG systems, control during startup is not entirely clear. Startup characteristics from power turbine startup through synchronization to the system bus are ascertained using an overall shipboard system model.Findings – A startup sequence control is clarified for a combination of gas valve operation and load bank. A prototype constructed on the basis of the simulation. As a result, in the startup process, so as to limit speed overshooting that is 0.83 p.u. at 100 percent output from main diesel engine as the severest condition. The synchronization to the system bus is attained, and highly satisfactory results are achieved.Orig...