CN115817779A - A marine electric propulsion system based on LNG - Google Patents

Abstract

The invention discloses an LNG-based marine electric propulsion system, which belongs to the technical field of ship control. The LNG power generation module in the system is used to react and generate power in an LNG reactor after low-pressure vaporization; The mass pump, heat exchanger 2, steam turbine and heat exchanger are circulated to complete the collection of mechanical work, and the steam turbine is connected to the DC generator to generate electricity; the LNG fuel cell reactor and the DC generator are connected to the electric push module for power generation. Electricity storage; heat exchanger one and LNG low-pressure vaporizer, LNG fuel cell reactor and heat exchanger two respectively construct a heat exchange cycle path to increase the potential energy difference between the high and low temperature end of the Rankine cycle module. As a pure electric system, this system fully embodies the environmental protection advantages of clean energy, and the idea of using LNG cold energy and reaction waste heat to improve the efficiency of the Rankine cycle has comprehensively improved the economy and energy saving of the system.

Description

A marine electric propulsion system based on LNG

technical field

The invention belongs to the technical field of ship control, and in particular relates to an LNG-based ship electric propulsion system.

Background technique

In recent years, out of human needs for sustainable development, the restrictive requirements for the discharge of marine pollutants have become increasingly stringent, and the control of discharge in specific areas has also become more intense. Traditional fossil fuels have made an indelible contribution to the survival and development of mankind as the main energy source for a long time, and have long been used as the main source of ship power in the field of maritime shipping. However, under the aforementioned background conditions, due to the traditional fuel There are problems such as limited reserves, low energy utilization rate and serious pollution, and the subsequent application of fossil fuels will be restricted in many ways.

In order to solve the energy supply problem in the field of marine shipping under the premise of reducing pollution, those skilled in the art have proposed a solid oxide fuel cell and organic Rankine cycle combined power generation system based on LNG (liquefied natural gas, liquefied natural gas) cold energy utilization , see the technical solution disclosed in Chinese patent CN 102628402 A, which integrates the fuel cell gas turbine combined cycle, the organic Rankine cycle and the cold energy utilization of LNG. Efficiency and environmental pollution are a new type of power generation that is contradictory. The hydrogen in the fuel is directly converted into electrical energy with the help of electrolytes and oxygen in the air, which is not limited by the Carnot cycle efficiency, and the reaction temperature of solid oxide fuel cells is very high. Therefore, the exhaust waste heat can be recovered and utilized, combined with the effective utilization of the cold energy of liquefied natural gas, the power generation capacity of the system can be greatly increased, the cascade utilization of energy can be realized, and the air pollution can be reduced while improving the utilization efficiency of energy.

However, when gas turbines and other more power equipment are involved in the entire system, and LNG is mainly supplied to the gas pipeline network, the clean advantages of LNG itself cannot be maximized, and the pollution caused by the operation of the entire system In the current environment, especially in the shipping environment, it is still a practical problem that cannot be ignored. Therefore, if a marine electric propulsion system based solely on LNG can be designed, and the Rankine cycle and LNG cold energy utilization can be systemically integrated, it will not only enable the efficient conversion of natural gas, but also actively utilize the LNG cold energy and grade waste heat system to improve the Rankine cycle The efficiency of the system will fully improve the system's economy and energy saving, so that it can play a greater role in environmental protection, energy saving and emission reduction, better adapt to the current international trend, and make outstanding contributions to the sustainable development of mankind.

Contents of the invention

The purpose of the present invention is to solve the problems of system pollution and low energy utilization in the prior art, and provide a marine electric propulsion system based on LNG. The cold energy and reaction waste heat are used to improve the efficiency of the Rankine cycle, so that the economy, energy saving and environmental protection of the system have been comprehensively improved.

The present invention is realized like this: a kind of marine electric propulsion system based on LNG comprises LNG power generation module, Rankine cycle module and electric propulsion module; LNG power generation module comprises LNG liquid storage tank, LNG low-pressure vaporizer and LNG fuel cell reactor; the medium flowing in the Rankine cycle power generation module circulates through the working medium pump, heat exchanger 2, steam turbine and heat exchanger in turn to complete the collection of mechanical work, and the steam turbine is connected to the DC generator to generate electricity ; The LNG fuel cell reactor and the DC generator are connected to the electric push module for power storage; a heat exchange circulation path is respectively constructed between the heat exchanger 1 and the LNG low-pressure vaporizer, and between the LNG fuel cell reactor and the heat exchanger 2 It is used to increase the potential energy difference between the high and low temperature ends of the Rankine cycle module.

Further, the heat exchange cycle constructed between the heat exchanger one and the LNG low-pressure vaporizer is used to exchange heat between the cold energy in the LNG low-pressure vaporizer and the medium flowing in the Rankine cycle module, and reduce the flow of the medium flowing to the heat exchanger one. temperature.

Further, the heat exchange cycle constructed between the LNG fuel cell reactor and the heat exchanger is used to exchange heat between the grade waste heat generated in the reaction process of the LNG fuel cell reactor and the medium flowing in the Rankine cycle module, and improve the flow rate to The temperature of the medium at the second place of the heat exchanger.

Further, the electric propulsion module includes an energy storage battery and an electric propeller, and the electricity stored in the energy storage battery is used to drive the electric propeller to work.

Further, the electricity generated by the LNG fuel cell reactor and the DC generator is stored in the energy storage battery.

Further, an LNG valve is provided on the connecting pipeline between the LNG liquid storage tank and the LNG low-pressure vaporizer.

Further, a reheater is provided between the LNG low-pressure vaporizer and the LNG fuel cell reactor.

Beneficial effect:

1. The marine electric propulsion system disclosed in this application uses the LNG fuel cell reactor and the DC generator as the main power source respectively to construct a pure electric power supply system, compared with the propulsion system built on solid oxide fuel , the system can maximize the clean advantages of liquefied natural gas itself, reduce the pollution of the system to the environment, and effectively solve the problem of marine pollutant discharge;

2. This application uses LNG cold energy to reduce the temperature at the low-temperature end of the Rankine cycle, and at the same time uses the grade waste heat of the LNG fuel cell reactor to increase the temperature at the high-temperature end of the Rankine cycle, thereby significantly increasing the potential energy difference between the high and low-temperature ends of the Rankine cycle , which can effectively improve the Rankine cycle efficiency;

3. The potential energy difference at the high and low temperature end of the Rankine cycle is based on the utilization of LNG cold energy and the utilization of reactor waste heat, which maximizes the utilization of LNG cold energy, so the system has obvious energy saving and economical efficiency;

4. The electric power stored in the energy storage battery in the electric propulsion system disclosed in this application comes from the electric energy generated by the DC motor in the Rankine cycle and the electric energy generated by the LNG fuel cell reactor. It can also provide double protection for the supply of marine power.

Description of drawings

Fig. 1 is a system structure diagram of an LNG-based marine electric propulsion system;

Among them, 11-LNG storage tank, 12-LNG low-pressure vaporizer, 13-LNG fuel cell reactor, 14-LNG valve, 15-reheater;

21- heat exchanger one, 22- working medium pump, 23- heat exchanger two, 24- steam turbine, 25- DC generator;

31-energy storage battery, 32-electric propeller.

Detailed ways

The preferred embodiments of the present invention are described in detail below, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, so as to define the protection scope of the present invention more clearly.

Embodiment 1. A marine electric propulsion system based on LNG

In order to further enhance the utilization of LNG cold energy and system grade waste heat, to fully improve the efficiency of the Rankine cycle, and effectively improve the economy and energy saving of the marine electric propulsion system, this embodiment discloses an LNG-based marine electric propulsion The system, including the LNG power generation module, the Rankine cycle module and the electric push module, realizes the optimization of the system through the cooperation of the three modules.

The LNG power generation module includes an LNG liquid storage tank 11, an LNG low-pressure vaporizer 12, and an LNG fuel cell reactor 13 connected in sequence. The liquefied natural gas stored in the LNG liquid storage tank 11 enters the LNG low-pressure vaporizer 12 for low-pressure gasification, and the gas formed after vaporization The gaseous natural gas is sent to the LNG fuel cell reactor 13 through the pipeline to convert the chemical energy of the natural gas into electrical energy, and complete the power generation process of the LNG fuel cell.

The Rankine cycle module includes a heat exchanger 21, a working fluid pump 22, a heat exchanger 23 and a steam turbine 24, and the medium flowing in the Rankine cycle power generation module flows through the working medium pump 22, heat exchanger 23, steam turbine 24 and The heat exchanger 21 circulates and flows to complete the collection of mechanical work, and the steam turbine 24 is connected with the DC generator 25 to realize the power generation process of the Rankine cycle.

A heat exchange cycle is constructed between the heat exchanger one 21 and the LNG low-pressure vaporizer 12, which is used to exchange heat between the cold energy in the LNG low-pressure vaporizer 12 and the medium flowing in the Rankine cycle module, and reduce the flow to the heat exchanger one 21. Medium temperature; A heat exchange cycle is also constructed between the LNG fuel cell reactor 13 and the heat exchanger 23, in order to convert the grade waste heat generated in the LNG fuel cell reactor 13 reaction process to the medium flowing in the Rankine cycle module Perform heat exchange to increase the temperature of the medium flowing to heat exchanger 223; this design can effectively increase the potential energy difference between the high and low temperature ends of the Rankine cycle and improve the efficiency of the Rankine cycle, and the composition of the temperature difference is based on the cold energy of LNG It is realized by using the waste heat of the reactor and the reactor, so it has obvious energy saving and economy.

The electric propulsion module includes an energy storage battery 31 and an electric propeller 32, and the electricity stored in the energy storage battery 31 is used to drive the electric propeller 32 to work; the electric power generated by the LNG fuel cell reactor 13 and the DC generator 25 is stored in the energy storage battery 31 together serve as the power source of the electric propeller 32, and the common supply of power at both ends can realize the maximization of power storage.

On the connecting pipeline of LNG liquid storage tank 11 and LNG low-pressure vaporizer 12, be provided with the LNG valve 14 that control flow is used, also can arrange reheater 15 between LNG low-pressure vaporizer 12 and LNG fuel cell reactor 13, reheater 15 The temperature of the gaseous natural gas can be controlled and adjusted before it flows into the reactor for reaction.

All the electrical components used in this system are electrically connected with the main controller to facilitate the overall regulation through the main control terminal, so as to improve the smoothness of the operation process. The LNG valve 14 used is also an electronic valve, which is convenient for controlling The valve opening is adjusted.

The above is only an embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the description of the present invention and the contents of the accompanying drawings, or directly or indirectly used in other related technologies fields, all of which are equally included in the scope of patent protection of the present invention.

Claims (7)

1. A marine electric propulsion system based on LNG, characterized in that it comprises an LNG power generation module, a Rankine cycle module and an electric push module; The LNG power generation module includes a sequentially connected LNG liquid storage tank, LNG low-pressure vaporizer and LNG fuel cell reactor; The medium flowing in the Rankine cycle power generation module circulates among the working fluid pump, heat exchanger 2, steam turbine and heat exchanger in sequence to complete the collection of mechanical work, and the steam turbine is connected to the DC generator to generate power; Both the LNG fuel cell reactor and the DC generator are connected with the electric push module for power storage; A heat exchange cycle path is constructed between the first heat exchanger and the LNG low-pressure vaporizer, and between the LNG fuel cell reactor and the second heat exchanger to increase the potential energy difference between the high and low temperature ends of the Rankine cycle module. 2. a kind of LNG-based marine electric propulsion system as claimed in claim 1, is characterized in that, the heat exchange cycle that constructs between heat exchanger one and LNG low-pressure vaporizer is used for the cold energy in LNG low-pressure vaporizer and Rankine The medium flowing in the circulation module performs heat exchange, reducing the temperature of the medium flowing to the heat exchanger. 3. A kind of marine electric propulsion system based on LNG as claimed in claim 1, is characterized in that, the heat exchange cycle that builds between LNG fuel cell reactor and heat exchanger two is used for LNG fuel cell reactor reaction process The generated grade waste heat exchanges heat with the medium flowing in the Rankine cycle module, increasing the temperature of the medium flowing to the second place of the heat exchanger. 4. The LNG-based marine electric propulsion system according to claim 1, wherein the electric propulsion module includes an energy storage battery and an electric propeller, and the electricity stored in the energy storage battery is used to drive the electric propeller to work. 5. A kind of LNG-based marine electric propulsion system as claimed in claim 4, characterized in that, the electricity generated by the LNG fuel cell reactor and the DC generator is all stored in the energy storage battery. 6. A kind of LNG-based marine electric propulsion system as claimed in claim 1, characterized in that an LNG valve is provided on the connecting pipeline of the LNG liquid storage tank and the LNG low-pressure vaporizer. 7. A kind of LNG-based marine electric propulsion system as claimed in claim 1, characterized in that a reheater is arranged between the LNG low-pressure vaporizer and the LNG fuel cell reactor.

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