Ship Propulsion System with Auxiliary Drive Energy Recovery
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Solution Overview
Problem
Large ships with two propulsion trains face inefficiencies and increased fuel consumption when operating at reduced speeds, as their propulsion engines are not optimized for slow steaming, leading to wasted advantages and higher maintenance costs.
Innovation Solution
A propulsion system with two drive trains, where one main drive powers both propeller shafts directly and the second is powered by electrical energy generated from the first, using auxiliary drives and energy recovery from exhaust gases, optimizing efficiency and reducing fuel consumption at low speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If two main propulsion engines are operated at reduced speeds for slow steaming, then fuel consumption increases because the engines are not operating within their optimal operating range, but operating at higher speeds would reduce fuel efficiency
Solution Approach 1:
The propulsion system is segmented into two independent drive trains, each with its own main propulsion engine and auxiliary drive. This allows selective operation of one or both main drives depending on speed requirements, enabling optimal operating points to be maintained while providing redundancy for reliability.
Solution Approach 2:
The auxiliary drives are designed with multi-functionality, serving both as propulsion assistance and as generators for electrical energy production. When one main drive operates optimally, the auxiliary drive can generate electricity to power the second propeller shaft, maintaining system reliability without compromising fuel efficiency.
2Reliability
If both propeller shafts are driven directly by separate main drives, then propulsion redundancy is maintained, but specific fuel consumption increases at low speeds due to suboptimal engine operation
Solution Approach 1:
The system dynamically reconfigures its power transmission path based on operating conditions. At low speeds, the auxiliary drive switches between motor and generator modes, allowing the main drive to operate at optimal points while still providing propulsion to both shafts through electrical coupling, thus maintaining redundancy without fuel penalty.
Solution Approach 2:
The auxiliary drive acts as an intermediary between the single operating main drive and the second propeller shaft. By converting mechanical energy to electrical energy and back, it enables the main drive to operate at optimal speeds while still delivering power to both propellers, reducing specific fuel consumption while maintaining propulsion capability.
3Use of energy by moving object
If electrical energy is generated from exhaust gases and onboard power, then energy efficiency is improved, but the complexity of the energy management system increases
Solution Approach 1:
The auxiliary drive serves itself by automatically switching between motor and generator modes based on system needs. When the main drive operates at optimal speed, the auxiliary drive autonomously generates electricity; when additional propulsion is needed, it automatically draws electricity. This self-regulating behavior reduces the complexity of external energy management control.
Solution Approach 2:
The system recovers waste heat energy from exhaust gases and converts it to electrical energy through the auxiliary drive operating as a generator. This recovered energy is then utilized to power the second propeller shaft or contribute to onboard power needs, improving overall energy efficiency by utilizing previously wasted thermal energy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration improves propulsion efficiency, reduces specific fuel consumption, and enhances operational safety by allowing the ship to operate effectively with only one main drive at low speeds, while also reducing maintenance needs and utilizing energy from exhaust gases.
Implementation Method 1
a first auxiliary drive (35) is operated as a generator for generating electrical energy from rotations of a first propeller shaft (31)
Implementation Method 2
the second auxiliary drive (45) is operated as a motor driven by the first auxiliary drive (35) for driving a second propeller shaft (41)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a propulsion system (2) for a ship with two drive trains (3, 4). Each drive train (3, 4) comprises a propeller shaft (31, 41), a main drive (33, 43) designed as an internal combustion engine for driving the propeller shaft (31, 41), and a secondary drive (35, 45) designed as a rotating electric machine, which can be operated either as a drive for the propeller shaft (31, 41) or as a generator driven by the propeller shaft (31, 41).The auxiliary drives (35, 45) are designed and connected in such a way that both propeller shafts (31, 41) can only be driven by means of work performed by exactly one main drive (33, 43), in that a first auxiliary drive (35, 45) is operated as a generator to generate electrical energy from rotations of a first propeller shaft (31, 41) driven directly by the main drive (33, 43), and the second auxiliary drive (35, 45) is operated as a drive of the second propeller shaft (31, 41) driven by the first auxiliary drive (35, 45).