SMX® Ocean AIP STRUCTURE
At the 27th of October 2014 the French Industrial Group DCNS (Direction des Constructions Navales & Service) announced a concept of a new Conventional AIP submarine – a SMX® Ocean. The boat on the First day of the 24th International Naval Defense & Maritime Exhibition & Conference “EURONAVAL 2014”in Le Bourget (France) was represented. The new conventional submarine concept SMX® Ocean opens the new generation of convention AIP submarines. Drastic alterations had undergone an AIP system of SMX® Ocean that is one of the main parts of submarine propulsion system. In accordance with DCNS’s announcement, this system is based on a new concept as well. New AIP concept attracted interest of many visitors of exhibition. In our brief presentation we shall speak about new AIP concept only.
WHAT INNOVATIONS PROVIDE NEW POSSIBILITIES OF SMX® Ocean?
New SMX® Ocean submarine (concept) contain many different innovations. DCNS demonstrates them in many different advertizing videos. In current presentation we shall discuss innovations regarding to Air Independent Propulsion system the of SMX® Ocean submarine only. First, the SMX® Ocean submarine has layout and dimensions of hull the same as the French nuclear powered submarine SSN Barracuda (Suffren class). Such decision, accepted for conventional (diesel powered) submarine, had created conditions to increase total and submerged endurance of boat. Submarine SMX® Ocean with submerged displacement 5300 tons will be the biggest conventional boat in the world. Second, it had been announced that the SMX® Ocean submarine will operate one week submerged with average speed 14 knots. It is serious enough announcement. To provide such performance, the propulsion system has to have power up to 1.8MWe during whole operation time. Third, it is a new generation of AIP system. In accordance with announcement of DCNS, the new submarine will be fitted with integrated AIP, which comprises two powered fuel cells and diesel fuel reformer for onboard hydrogen production instead of traditional MESMA (closed cycle steam turbine) AIP system.
ATDFR and TWO IT-SOFC are the POSSIBLE COMPONENTS of SMX® Ocean
Analysis of existing information and comments make possible to define the best configuration of the new integrated AIP system and determine main performances of AIP components. Comprehensive analysis of all main types of fuel cells shows that PEMFC and SOFC only are suitable to decide such solution. PEMFC and SOFC competed against each other. Analyzing the different types of diesel-fuel reformers together with fuel cells, we have arrived at a conclusion that the best solution is integrated AIP that contains Auto-thermal Diesel-Fuel Reformer (ATDFR) and Two Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFC).We suppose that the most likely solution is realized in SMX® Ocean AIP. We had fulfilled some calculations to define main performances of fuel and liquid oxygen feeding and storage systems and show variants how to locate LOX and fuel tanks in AIP section.
ANALYSIS OF SUPPOUSED SMX® Ocean AIP STRUCTURE
Comprehensive analysis of possible variants of integrated AIP system for French submarine SMX® Ocean (Concept) in analytic report Bakst A.–Submarine SMX® Ocean Concept AIP Structure is represented. Table of Contents
2. SMX® Ocean SUBMARINE HULL DIMENSIONS
3. SMX® Ocean SUBMARINE CONCEPT GOALS
4. SMX® Ocean AIP STRUCTURE
5. ANALYSIS OF SMX® Ocean AIP COMPONENTS
6. SMX® Ocean SUBMARINE AIP PERFORMANCE CALCULATION
INTEGRATED DIESEL FUEL REFORMER – FUEL CELL (IDFR-FC) REQUIREMENTS
DIESEL FUEL PROCESSING
There are three main technologies for reforming of hydrocarbon fuels. They are Steam Reforming (SR), Partial Oxidation (POX) and Auto-thermal reforming (ATR). All these technologies are intended for a syngas (mixture CO+H2) production and use different catalysts which provide high effectiveness of processes. It should be noted that there are two different POX processes. They are: so-called Thermal Partial Oxidation (TPOX) and Catalytic Partial Oxidation (CPOX). Auto-thermal reforming (ATR) uses oxygen and steam in a reaction with diesel fuel to form syngas. The reaction takes place in a single chamber where the diesel fuel is partially oxidized. The reaction is exothermic due to the oxidation. The reactions can be described by the following equation:
Reformer Input Fuel Oxygen Water Reformer Output Hydrogen Pure Hydrogen cannot be produced from diesel fuel by reforming. SR, POX, and ATR produce so-called “Syngas” Water Gas Shift Reaction In practice, reformer’s Output is a mixture: H2, CO, CO2, H2O, CH4, C.
AIP SYSTEM CHALENGES
Pure HYDROGEN use as a fuel Proton Exchange Membrane Fuel Cells (PEMFC) and Phosphoric Acid Fuel Cells (PAFC). AIP SYSTEM CHALENGES 1. To obtain pure HYDROGEN from diesel fuel, then Carbon monoxide, Carbon dioxide, Water, Methane, Carbon and Sulfur have to be removed from reformer products. 2. Reformer products has temperature > 600°C. They have to be cooled till 80°C-100°C if they will be used in PEMFC and they have not to be cooled if they will be used in SOFC. To obtain pure HYDROGEN the reforming reactor has to be fitted with following additional equipment: – High temperature Water-Gas-Shift Reactor; – Low temperature Water-Gas-Shift Reactor; – Pressure Swing Absorber; – Heat Exchanger.
ONLINE OF PRESENTATION
1. Submarine SMX® Ocean AIP System Features 2. Marine Diesel Fuel; 3. Integrated Diesel fuel Reforming – PEMFC; 4. PEMFC Characterization; 5. Integrated Diesel fuel Reforming – SOFC; 6. SOFC Characterization; Presentation contains two parts: SR-PEMFC is the Probable Composition of Integrated AIP for Submarine SMX® Ocean. Part 1. DFATR-SOFC is the Supposed AIP Structure of Submarine SMX® Ocean (concept). Part 2. Pictures, graphs, layouts and diagrams used in the presentation are intended for text illustration only.
DIESEL FUEL AUTOTHEMPERMAL REFORMER – SOFC MARINE DIESEL FUELS
DIESEL FUEL AUTOTHEMPERMAL REFORMER – SOFC
IDFR-FC SYSTEM EFFICIENCY
There are some methods to define integrate diesel fuel reforming – fuel cell (IDFR-SOFC) efficiency. Usually it is used the simple method that described below. Reformer efficiency is defined as it follows Fuel cell efficiency IDFR-SOFC system efficiency. ATR efficiency ≈ 70%…80% Fuel Cell efficiency ≈ 50%…60% System efficiency 35%…48%
SIMPLIFIED DIAGRAMS OF SOFC
SOFC TUBULAR DESIGNS
SOFC PLANAR DESIGNS
SOFC ADVANTAGES AND DRAWBACKS
It is well known, that existing high temperature SOFCs have the maximal life time and electric efficiency among other types of fuel cells. If such fuel cell operates in borders of CHP system then AIP overall efficiency can reach up to 90%. In spite of slow starting up of SOFC and high temperature corrosion, SOFC is one of the best pretender to be source of electric power for submarine. We shall show how influence of HT-SOFCs’ drawbacks can be minimized. Currently, due to new materials application, the low or intermediate temperature SOFC (LT-SOFC / IT-SOFC) obtained fast development. In some literature sources they are called as the third generation of SOFCs. HT-SOFCs have high efficiency, high stability, fuel flexibility and internal reforming. LT-SOFCs or IT-SOFCs has lower operating temperature (500°C – 800°C), and add to existing list of advantages a longer life time, lower corrosion activity, application of metallic components instead of expensive ceramic and faster starting up mode.
THE THIRD GENERATION OF SOFC
New Materials Application List of advantages
– High cell voltage (up to 1.0V);
– High power density (up to 3.5W/cm2);
– Reduction of high temperature corrosion (bipolar plates from stainless steel);
– Reduction start up time (up to some hours); – Increasing life time (up to 40000-60000 hr);
– Cost reduction
Eric D. Wachsman Redox Power System’s Revolutionary SOFC Technology; 25 Years of Persistence
INTERMEDIATE TEMPERATURE SOFC COMPONENTS (Cont’d) ELECTROLYTE
Some crystallographic families have shown high oxide-ion mobility: fluorites (e.g.,stabilised zirconia, doped ceria or δ-Bi2O3), oxygen-deficient perovskites (e.g., doped LaGaO3),
aurivillius (e.g., Bi2MexV1-xO5.5-δ-BIMEVOX), pyrochlores (e.g., Gd2(Ti1-xZrx)O6O’), apatites (e.g.,Ln10(SiO4)6O3) or scheelites (AMoO4). Figure below shows the conductivity for representative compounds of these families.
SOFC STARTUP PERFORMANCE
The SOFC heating process shown in the right diagram is very slow. Startup durability is equaled of 9 hours. Such process provides uniform heating.
The left diagram shows startup SOFC 50-250 kW stack for measurement and simulation. Startup takes about 400 seconds (6.6 min). However, it is not the fastest startup. Projected trend of startup development is about 2 minutes.
[ 1] Large SOFC. Towards a Large SOFC Power Plant Project #019739 Final Report. 2010
SOFC RESULTS AND PROJECTED TRENDS
Potential SOFC Characteristics
Power – Hundreds of kW to MW
Cost – 1000Euro/kW
Durability – 50000 hrs
Electrical efficiency – 60%
CHP mode efficiency – 90%
SOFC COST ESTIMATION
Costs continue to decrease as power goes up
General trend continues: SOFC<LT-PEMFS<HT-PEMFS
Source: Brian D. James Andrew B. Spisak Whitney G. Colella
Cost Estimates of Stationary Fuel Cell Systems Strategic Analysys., 7Nov2012