Comparing exergy losses and evaluating the potential of catalyst-filled plate-fin and spiral-wound heat exchangers in a large-scale Claude hydrogen liquefaction process

Detailed heat exchanger designs are determined by matching intermediate temperatures in a large-scale Claude refrigeration process for liquefaction of hydrogen with a capacity of 125 tons/day. A comparison is made of catalyst filled plate-fin and spiral-wound heat exchangers by use of a flexible and robust modeling framework for multi-stream heat exchangers that incorporates conversion of ortho-to para-hydrogen in the hydrogen feed stream, accurate thermophysical models and a distributed resolution of all streams and wall temperatures. Maps of the local exergy destruction in the heat exchangers are presented, which enable the identification of several avenues to improve their performances. The heat exchanger duties vary between 1 and 31 MW and their second law energy efficiencies vary between 72.3% and 96.6%. Due to geometrical constraints imposed by the heat exchanger manufacturers, it is necessary to employ between one to four parallel plate-fin heat exchanger modules, while it is possible to use single modules in series for the spiral-wound heat exchangers. Due to the lower surface density and heat transfer coefficients in the spiral-wound heat exchangers, their weights are 2–14 times higher than those of the plate-fin heat exchangers. In the first heat exchanger, hydrogen feed gas is cooled from ambient temperature to about 120 K by use of a single mixed refrigerant cycle. Here, most of the exergy destruction occurs when the high-pressure mixed refrigerant enters the single-phase regime. A dual mixed refrigerant or a cascade process holds the potential to remove a large part of this exergy destruction and improve the efficiency. In many of the heat exchangers, uneven local exergy destruction reveals a potential for further optimization of geometrical parameters, in combination with process parameters and constraints. The framework presented makes it possible to compare different sources of exergy destruction on equal terms and enables a qualified specification on the maximum allowed pressure drops in the streams. The mole fraction of para-hydrogen is significantly closer to the equilibrium composition through the entire process for the spiral-wound heat exchangers due to the longer residence time. This reduces the exergy destruction from the conversion of ortho-hydrogen and results in a higher outlet mole fraction of para-hydrogen from the process. Because of the higher surface densities of the plate-fin heat exchangers, they are the preferred technology for hydrogen liquefaction, unless a higher conversion to heat exchange ratio is desired.publishedVersion©2019 The Authors. Published by Elsevier Ltd on behalf of Hydrogen Energy PublicationsLLC. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/

Hydrogen bunkering from a fuel island onto fishing vessels

Decarbonizing the fishing and aquaculture sector is an important goal for Norway as well as for the global shipping trade. Hydrogen is potentially a good fit for the energy demand of fishing vessels. For the fleet to switch to hydrogen as primary fuel, solutions for ensuring sufficient energy onboard must be found. One such solution could be to bunker the hydrogen at sea, in locations closer to the areas of operation of a fishing fleet. In the present work, we have investigated the bunkering of 250 bar gaseous hydrogen onto fishing vessels that require 4000 kWh of energy onboard. The first part focuses on the bunkering of a single vessel and an analysis of the technical parameters that affect and constrain the hydrogen bunkering rate. The second part focuses on the bunkering of several fishing vessels from a hydrogen refuelling station located offshore.Hydrogen bunkering from a fuel island onto fishing vesselspublishedVersio

Dynamic Analysis of Large-Scale Transfer Operations for Liquid Hydrogen

Transfer operations from onshore tanks to ship are a crucial component that needs to be understood and optimized to allow for large-scale seaborne transport of liquid hydrogen (LH2). In this work, we present a dynamic model that includes the main components required for loading operations of LH2. An important aspect for scaling-up is to quantify the effect of heat ingress in the pipelines. We implement a detailed pipeline model that we use to compare different insulation alternatives. Due to the nature of loading operations, the dynamic analysis, control strategy and controller tunings play an important role in the dynamic behaviour of the system. Here, we systematically analyse the dynamic behaviour of the system and develop a control strategy for LH2 loading operations. We implement this control strategy in the simulation model for LH2 loading. Keywords: Liquid hydrogen, Dynamics, Process control, Loading, Transfer operations, PID controlDynamic Analysis of Large-Scale Transfer Operations for Liquid HydrogenacceptedVersio

The role of process synthesis in the systematic design of energy efficient fossil fuel power plants with CO2 capture

CO2 capture and storage has a potential of reducing CO2 emissions from large point sources such as fossil fuel power plants. CO2 capture is associated with substantial capital expenditures, operational expenditures dominated by high energy use and potential operational restrictions on the underlying industrial processes. The main focus of significant research efforts worldwide is thus to reduce investment costs and improve efficiency of capture technologies. The systematic methodologies developed in our group at SINTEF/NTNU for design of energy efficient fossil fuel power plants with CO2 capture are presented and show the importance of utilizing process synthesis in the design of such plants. These methods range from targeting minimum capture work for different CO2 capture processes, optimization methods for process design of pre- and post-combustion capture processes, developing surrogate models for optimization.publishedVersion© 2013 AIDIC Servizi S.r.l. This is an open access article

Low-pressure liquid CO2 terminal - a model study of the loading of a liquid CO2 tanker

Low-pressure liquid CO2 terminal - a model study of the loading of a liquid CO2 tankeracceptedVersio

Cryogenic CO2 condensation and membrane separation of syngas for large-scale LH2 production.

acceptedVersio

Hydrogen re-liquefaction Process for Boil-off Gas Handling on a Large-scale Liquid Hydrogen Carrier

With the recent focus on hydrogen, seaborne shipping is considered an option for the large-scale transport of liquid hydrogen (LH2). For efficient shipping, boil-off gas (BOG) from the cargo tanks needs to be optimally utilized. This work suggests a BOG handling system (BHS) producing fuel for an LH2 carrier and liquefying excess BOG in a hydrogen Claude cycle. The process offers a simple configuration that does not require a refrigerant makeup facility. The simulation results of the BHS also show relatively low specific power consumption (5.7 to 2.6 kWh/kgLH2) with a good utilisation of cold energy in BOG. The sensitivity analysis with the BOG to fuel (BtF) ratio shows that a higher BtF gives a simpler configuration and a smaller size liquefier, saving capital costs. However, the optimal capacity of the BHS needs to be determined based on the techno-economic performance of the entire system of the LH2 carrier. Keywords: Hydrogen, Liquefaction, Liquid hydrogen carrier, Transport, Boil-off gas, Claude cycleacceptedVersio

A pragmatic orthotropic elasticity-based damage model with spatially distributed properties applied to short glass-fibre reinforced polymers

This article presents a simple progressive damage model for quasi-brittle materials, combining orthotropic elasticity with a scalar damage model including spatial variation of the damage initiation strain and the crack band method for softening regularization. The model’s performance is first analyzed from a numerical point of view and then demonstrated for tensile tests (, and ), open-hole tensile tests () and three-point bending ( and ) tests of short fibre-reinforced polypropylene with 15 wt.% and 30 wt.% glass fibres. Despite its simplicity, the model captures the anisotropic elastic and inelastic behaviour observed in experiments. The model is applicable for orthotropic brittle or quasi-brittle materials, where the variability in elastic properties is negligible and the orientation dependency of the fracture strain is small or not relevant for the application.publishedVersio

Large-scale production and transport of hydrogen from Norway to Europe and Japan: Value chain analysis and comparison of liquid hydrogen and ammonia as energy carriers

Low-carbon hydrogen is considered as one of the key measures to decarbonise continental Europe and Japan. Northern Norway has abundant renewable energy and natural gas resources which can be converted to low-carbon hydrogen. However, Norway is located relatively far away from these markets and finding efficient ways to transport this hydrogen to the end-user is critical. In this study, liquefied hydrogen (LH2) and ammonia (NH3), as H2-based energy carriers, are analysed and compared with respect to energy efficiency, CO2 footprint and cost. It is shown that the LH2 chain is more energy efficient and has a smaller CO2 footprint (20 and 23 kg-CO2/MWhth for Europe and Japan, respectively) than the NH3 chain (76 and 122 kg-CO2/MWhth). Furthermore, the study finds the levelized cost of hydrogen delivered to Rotterdam to be lower for LH2 (5.0 EUR/kg-H2) compared to NH3 (5.9 EUR/kg-H2), while the hydrogen costs of the two chains for transport to Japan are in a similar range (about 7 EUR/kg-H2). It is also shown that under optimistic assumptions, the costs associated with the LH2 chain (3.2 EUR/kg-H2) are close to meeting the 2030 hydrogen cost target of Japan (2.5 EUR/kg-H2). Keywords Techno-economic analysisLiquid hydrogenAmmoniaLong distance transportacceptedVersio