Liquefaction Performance Research Articles

Experimental Study on Distillation Column Parameters for Liquefaction Device of Low Concentration Coalbed Methane

The input-output ratio and comprehensive energy consumption of low concentration coalbed methane cryogenic liquefaction devices are determined by the process parameters in control of the distillation column. In order to accurately control the actual operation process of the distillation column, the effect of the operating temperature of the distillation column on the liquefaction performance of a cold box was studied experimentally, and the optimal control parameters of the distillation column were obtained. The results show that the recovery rate of methane decreases with the increase in temperature at the top of the distillation column, and when this temperature is higher than −178 °C, the methane recovery rate drops sharply to below 90%. When the temperature at the bottom of the distillation column rises from −154 °C to −142.7 °C, the purity of LNG products is improved, and when this temperature is increased to −143.5 °C, the purity of products at the bottom of the distillation column reaches the standard, and can be stored safely. In actual operation, the evaporation temperature at the bottom of the column should not be higher than −140 °C. In the process of industrial plant design, measures should be taken to reduce the interaction of the temperature regulation at the top and bottom of the distillation column. When selecting the refrigerant circulation compressor, the leakage of the refrigerant should be considered to maintain the operating pressure of the refrigeration cycle.

Geotechnical characterization and liquefaction evaluation of gravelly reclamations and hydraulic fills (Port of Wellington, New Zealand)

In the 2016 Mw7.8 Kaikōura earthquake, widespread liquefaction occurred in the reclamations at CentrePort, Wellington (New Zealand), while less intense shaking during two earthquakes in 2013 produced only some liquefaction manifestation over isolated areas of the port. The two types of reclamations, comprised of end-dumped gravelly fills and hydraulically placed silty-sandy fills, are not well represented in current empirical simplified liquefaction procedures. Comprehensive CPT investigations are presented and used to characterize the fills, and then perform CPT-based liquefaction evaluation for the three earthquakes that affected the port in 2013 and 2016. The results of the analyses are compared to observations of liquefaction performance and are examined in relation to the soil and deposit characteristics of the fills. The CPT-based liquefaction assessment was generally consistent with observations, though clear shortcomings and limitations of these procedures were also evident. The paper scrutinizes conventional engineering procedures for liquefaction assessment when applied to non-conventional or problematic soils for such assessment, with reference to a well-documented case history.

Liquefaction performance and deformation of slightly sloping site in floodplains of the lower reaches of Yangtze River

Serious seismic damage is expected owing to the occurrence of lateral displacement following soil liquefaction after a strong earthquake. Currently, there is a need for increased research on the lateral deformation occurring inside a liquefied foundation and its spatial distribution characteristics. Considering the initial geostatic stress of a slightly sloping site, a finite-element model that reflects the liquefaction-induced slippage of the liquefiable site with a slightly inclined ground was designed. According to the results, the steeper the ground slope is, the weaker the soil liquefaction in the slope body will be. As the ground inclination and the intensity of input ground motion vary, the lateral slippage of the liquefiable soil layer transforms from the liquefaction-induced slipping along a single sliding surface to that along multiple sliding surfaces. The dominant lateral displacement of liquefiable soil layers in the slope body changes as well, from liquefaction-induced slippage of soil to largely large single-direction accumulated shear deformation of softening soil, as a result of the drastically reduced intensity of the liquefiable soil. In addition, a similar linear relationship is found among the maximum lateral displacement, the ground settlement near the slope crest, and the ground uplift near the slope foot.

Plasma-enabled liquefaction of lignocellulosic biomass: Balancing feedstock content for maximum energy yield

Plasma-enabled liquefaction (PEL) is an emerging technology to transform renewable biomass into value-added fuels and chemicals through the plasma-induced highly-reactive chemical reactions. However, biomass dramatically ranges in the feedstock content in terms of hemicelluloses, cellulose, lignin, and ash, strongly affecting the liquefaction performance. Here, we performed the liquefaction of three typical lignocellulosic materials (sawdust, corncob and rice straw) with different feedstock contents in a PEL system. The influence of the catalyst content and the reaction time on the degradation of each biomass was investigated to understand the effect of the feedstock content on liquefaction yield. The results confirmed that the chemical contents of the lignocellulosic biomass especially the amount of lignin and ash significantly affected the liquefaction yield, the quality of liquid products and the distributions of the chemicals obtained. Compared with the PEL performance of corncob and rice straw, the higher energy yield (liquid fuels) was achieved in the PEL of sawdust, owing to higher content of lignin and less ash inside. Moreover, possible reaction pathways of lignocellulose biomass liquefaction were deduced based on the chemical analysis. Overall, this work demonstrated that the proposed PEL strategy could be a promising approach for rapid biomass conversion with high energy efficiencies.

Hydrothermal Liquefaction of Polycarbonate (PC) Plastics in Sub-/Supercritical Water and Reaction Pathway Exploration

Plastic pollution is one of the most important environmental issues being faced today. In this work, the hydrothermal liquefaction performance of polycarbonate (PC) in sub-/supercritical water was investigated using a quartz tube reactor. Response surface methodology (RSM) was employed to demonstrate the correlation between reaction conditions and liquefaction efficiency of PC. The conversion selectivity and product recovery efficiency of PC were also analyzed. Moreover, according to the experimental results, the liquefaction reaction pathways of PC were speculated. In addition, based on the established reaction pathways, the lumped parameter method was also used to calculate the liquefaction kinetics of PC. The results showed that phenol was the largest liquefied product of PC, followed by 4-isopropylphenol (IPrP) and 4-isopropenylphenol (IPP), and the recovery efficiency of these three components determined the level of liquefaction efficiency. The PC liquefaction favored a mild reaction temperature, long residence time, and low feedstock concentration. Finally, for identified products, a 57.70 wt % carbon liquefaction efficiency was obtained with a 5 wt % feedstock concentration at 400 °C for 60 min. The liquefaction pathways showed that in the initial stage of depolymerization, 4-tert-butylphenol was first formed as a structural regulator, and phenol and IPP were the primary liquefied products. The IPrP, 4-ethylphenol, and p-cresol were the secondary products. The kinetic results indicated that the liquefied intermediates were easily converted to form phenol and IPP, and the IPP and IPrP were not directly converted to phenol, but there was a clear conversion relationship between them.

Five-stage sequential extraction of Hefeng coal and direct liquefaction performance of the extraction residue

Ultrasonic-assisted extraction (UAE) and direct liquefaction of the corresponding residue were conducted on an acid-washed ashless Hefeng bituminous coal (HBCAW). Petroleum ether (PE), carbon disulfide (CDS), methanol (MeOH), acetone and isometric CDS/acetone mixture (IMCDSAM) were used to sequentially extract HBCAW via UAE to obtain extracts (E1–E5). Gas chromatograph/mass spectrometer (GC–MS) analysis showed that most of the free molecules were extracted in the first two stages, and E1 and E2 were mainly consisted of aliphatics and alkanes. PE presented a strong extraction ability for the low polar compounds, and the average molecular weight of E2 was higher than E1. While E3 is more varied containing more complex molecules than E1 and E2. IMCDSAM was more favorable for the diffusion and dissolution of alcohols. Direct liquefaction performance suggested that the oil yields of Hefeng bituminous coal (HBC), HBCAW and the fifth stage extraction raffinate (ER5) were 66.00%, 63.57% and 44.11%, respectively, and that the conversion of ER5 was only 69.67%, much lower than HBC and HBCAW (82.75% and 82.68%). Higher yield of gaseous product for ER5 might be resulted from the looser coal structure by UAE process, resulting in more small molecules during the direct coal liquefaction.

Liquefaction performances of bread crusts in subcritical water

Hydrothermal liquefaction of bread crusts in subcritical water were performed in a micro-batch reactor. The influences of temperature (300 – 360 °C) and residence time (10-30 min) on bio-oil yield, boiling point distribution and functional groups in bio-oil were investigated. The results showed that bio-oil yield increased with increasing temperature and reaction time. Maximum bio-oil yield of 22.69wt% was obtained at 360 °C, 30min. The longer reaction time promoted the degradation of diesel to jet fuel and naphtha. The naphtha (C7-10) and jet fuel (C11-C15) increased to 29.9%, 51.82% at 30min from 20.49% and 36.14%, respectively. FT-IR analysis showed that esters, ketones, amides, acids and aldehydes were present in the bio-oil.

Comparative Study of the Catalytic Performances of Na2CO3 and γ-FeOOH in Hydroliquefaction To Propose a Two-Stage Lignite Catalytic Liquefaction Process

High oxygen content in lignite increases hydrogen consumption during hydroliquefaction, and simultaneously the produced water decreases hydrogen partial pressure, which negatively affects lignite liquefaction behaviors. Therefore, the liquefaction performances and oxygen-removal behaviors of Xilinhaote (XL) lignite during liquefaction at different temperatures in the presence of Na2CO3 (NC) and FeOOH (FO) were investigated. Results showed that the oxygen contents of liquefaction residues (LRs) obtained at 330–380 °C were 9.37–13.84% without catalyst and decreased to 7.90–13.02% and 6.38–11.73% with the addition of FO and NC, respectively. The addition of NC could promote the polarized breakdown of aromatic Caryl–Calkyl ether bonds via ionic pathways in the presence of water, which facilitated the depolymerization of lignite macromolecular structures, resulting in significant increase in coal conversions at 330–380 °C. To enhance liquefaction performance, an optimized two-stage catalytic liquefaction process for lignite with high oxygen content was proposed, which integrated the deoxygenation treatment of lignite over Na2CO3 and the hydrogenation of Na2CO3-treated lignite over iron catalyst. In the two-stage catalytic liquefaction processes, coal conversions and oil yields significantly increased to 90.66–92.73% and 52.73–57.56%, respectively, compared to 84.61% and 43.52% in single-stage liquefaction of XL over FO at 450 °C. Furthermore, in the two-stage catalytic liquefaction process, the treatment of XL over NC in stage I presented higher coal conversion (92.73%) and oil yield (57.56%) than those over FO in stage I (90.66% and 52.73%). Surprisingly, H2 consumption of the former (2.17%) was lower than that of the latter (2.91%).

Experimental investigation of the sloshing influence on FLNG liquefaction system

ABSTRACT With the exploitation of oil and gas resources in the ocean, the application of FLNG is more and more extensive. The FLNG ships will face with sloshing, which will exert an influence on the performance of the system. In order to study the effect of sloshing on the double mixed refrigerant liquefaction process, a sloshing platform of six degrees of freedom is built to perform the sloshing experiment of DMR system. The experimental on yaw, roll and pitch is carried out by measuring the temperature, pressure, flow and pressure difference at key nodes to analyze the effects of three different sloshing forms on the overall liquefaction performance and the equipment. It can be found that sloshing will reduce liquefaction performance and increase power consumption. The sloshing has an adverse effect on the distribution of fluid in the heat exchanger and reduces the heat transfer effect. In addition, the sloshing has a greater impact on the wound tube heat exchanger than the plate fin heat exchanger. The effect of the yaw is negligible and the effect of the roll is biggest. The research results can provide reference and guidance for offshore FLNG production.

Experimental study of flow distribution in plate–fin heat exchanger and its influence on natural gas liquefaction performance

The mal-distribution of gas–liquid mixtures has serious influences on the heat-transfer performance of plate–fin heat exchangers (PFHEs), which would result in an adverse effect on the stable and efficient operation of a natural gas liquefaction plant. Therefore, it is necessary to investigate the phase distribution performance of PFHEs and its influence on the natural gas liquefaction performance. In this study, a two-phase flow distribution experimental system was built to investigate the flow distribution characteristics of a PFHE under different working conditions. The effects of gas–liquid ratio, tilt angle, and sloshing on the gas–liquid distribution were studied. In addition, the influences of mal-distribution of the feed gas, nitrogen refrigerant, and mixed refrigerant (MR) on the heat transfer and natural gas liquefaction performance were analyzed through the Aspen Muse software. The results showed that the greater the gas–liquid ratio and tilt angle, the more uneven the liquid flow distribution. The efficiency of the MR process in the tilt condition was reduced by 5.2% to 18.5% compared to that in the horizontal condition. Compared with the tilt working condition, the sloshing could reduce the unevenness of the flow distribution. To satisfy the natural gas liquefaction rate of more than 90%, the critical standard deviation values of flow distribution unevenness of the feed gas, nitrogen refrigerant, MR, and MR under the tilt condition were 8.33, 2.95, 4.42 (liquid phase), and 1.42 (liquid phase), respectively. In the process design, to ensure the output and liquefaction rate, the amount of the refrigerant circulation and power consumption should be kept at the margin of approximately 6% and 4% for the nitrogen expander and MR liquefaction processes, respectively.

Influences of operating parameters on liquefaction performances of Tetra Pak in sub-/supercritical water

Liquefaction performances of waste Tetra Pak in sub-/supercritical water were evaluated in micro-batch reactors. The influences of temperature (300–420 °C), pressure (16–24 MPa), residence time (5–60 min) and feed concentration (5–40 wt%) on bio-oil yield, high heating value (HHV), and functional groups in bio-oil were investigated. The results showed that bio-oil yield firstly increased with increasing temperature and then decreased when the temperature exceeded 360 °C. Reaction time longer than 30 min gave a negative effect on bio-oil yield. The influence of pressure on bio-oil yield increased markedly from 16 MPa to 22 MPa, and then stabilized. The feed concentration higher than 20 wt% showed little influence on bio-oil yield. Maximum bio-oil yield of 35.55% was found at 360 °C, 22 MPa, 30 min and feed concentration of 20 wt%. HHV and energy recovery efficiency increased significantly with temperature, and maximum HHV of 48.747 MJ/kg and energy recovery efficiency of 46.49% were found at 420 °C, 20 MPa, 30 min and feed concentration of 20 wt%. The main compounds in bio-oil and morphology of the solid residue were also analyzed, and the possible liquefaction pathways of Tetra Pak were proposed.

Experimental Study on Seismic Response Characteristics of Liquefiable Soil Layers

ABSTRACT This study evaluates the effect of excess pore water pressure (EPWP) in liquefiable sand sub-layers on the seismic response of the soil profile. A series of shaking table tests were conducted to evaluate the liquefaction performance of a loose to dense subsurface sandy layer on the site effect phenomena. The results confirmed that the liquefied subsurface layer could attenuate or amplify the main characteristics of the seismic site response from 10% to 60%, primarily depending on the level of EPWP and soil softening in the layer. It is important to consider the detrimental effects of liquefaction-induced settlement in these estimations.

Effects of sulfur additive on the transformation behaviors of γ‐Fe2O3 and coal liquefaction performances under mild conditions

AbstractIn this paper, the effects of sulfur on liquefaction performances of coal and the transformation behaviors of γ‐Fe2O3 at the S/Fe atomic ratio of 0–1.3 under mild conditions were investigated. Compared with traditional liquefaction processes, the oil yield and coal conversion were insensitive to the addition of sulfur under mild conditions (temperature of 430°C, reaction pressure of 8.5–13.8 MPa). The optimum S/Fe atomic ratios at the initial H2 pressures of 4.0 and 8.0 MPa were 0.6 and 1.0, which were lower than those of traditional liquefaction processes. As the S/Fe atomic ratio increased from 0 to 0.6 (at the initial H2 pressure of 4.0 MPa), the oil yield and coal conversion increased by 4.0% and 3.8%, and this could be attributed to the synergistic effects between the relatively sulfur‐rich structure of pyrrhotite (Fe0.8917S) and the relatively high partial pressure of H2S. In addition, over 85% of sulfur was retained in the solid products, and the effect of S/Fe atomic ratio on the sulfur distribution was tiny. However, increasing H2 pressure was conducive to the transfer of sulfur to the gaseous products.

Liquefaction Hazards from “Inherited Vulnerabilities”

AbstractThis paper discusses two forms of soil liquefaction that are particularly damaging for engineering structures and communities: liquefaction of reclaimed land and urban liquefaction. Case histories from recent New Zealand earthquakes are used to illustrate characteristics of liquefaction manifestation and associated damage to land and structures. Liquefaction of gravelly fills at Wellington port and influence of finer sand‐silt fractions on the liquefaction performance of well‐graded gravelly reclamations are discussed. The importance of cross‐interactions between different layers and system response effects of liquefiable deposits are elucidated through 55 case history sites from Christchurch involving a wide range of observations from no liquefaction to severe liquefaction manifestation.

Depositional environment effects on observed liquefaction performance in silt swamps during the Canterbury earthquake sequence

Stratified silty soils deposited in back-swamp settings are shown through regional CPT-based analyses to have mitigating effects on the manifestation of liquefaction in Christchurch. Liquefaction triggering within these deposits is inadequately captured by simplified liquefaction assessment methodologies. Differing near-surface geology and depositional environments indicated in historical documents explain in part the limitations of current liquefaction evaluation procedures in southwest Christchurch. The historical swamp areas are shown through a regional CPT study to contain stratified silt/sand deposits or thick silt layers. Consideration of depositional environment distinguishes between liquefaction performances that are not able to be differentiated through the CPT-based liquefaction triggering assessment alone. CPT resolution is shown to be insufficient to capture the thin layering at these stratified sites, and the simplified liquefaction assessment methods do not take into account the effects of the stratification on pore water pressure movement within a soil profile. Instead, continuous sampling and careful logging of high-quality samples provide important insights on stratification at these silty soil swamp sites and in discerning differences in stratigraphy resulting from differences in depositional environment.

Efficient hydro-liquefaction of woody biomass over ionic liquid nickel based catalyst

The effective hydro-liquefaction process of sawdust is proposed over different ionic liquid Ni-based catalysts at 320 °C. This study investigated the relationship between ionic liquid composition and catalytic performance. The maximum sawdust conversion of 83.11% and liquid yield of 52.38% were achieved over the catalytic system including nickel chloride and 1-butyl-3-methyllimidazolium bromide ([Bmim]Br), suggesting that the anion in ionic liquid played an vital role on the sawdust hydro-liquefaction. The defined impact index was provided to further evaluate the liquefaction performance using ionic liquid Ni-based catalyst. The largest impact index obtained from [Bmim]Br/NiCl2 was in agreement with its excellent catalytic liquefaction performance. The analysis of ionic liquid Ni-based catalyst indicated the coordination interaction between ionic liquid and nickel chloride, which would be favorable to feedstock conversion and improve the bio-oil quality.According to the component distribution, the introduced ionic liquid Ni-based catalytic system was beneficial to sawdust cracking, resulting in the increased amount of smaller compounds. Additionally, the oil compositions highly depended on the employed type of ionic liquid.

Bio-oil Production by Thermochemical Catalytic Liquefaction of Bloom-Forming Cyanobacteria: Optimization Using Response Surface Methodology (RSM)

Experimental research on the thermochemical catalytic liquefaction of bloom-forming cyanobacteria (BC) was carried out to determine the effects of solvent, catalyst, reaction time, temperature, the ratio of raw material to solvent, and catalyst dosage on liquefaction performance. The liquefaction conditions were optimized by central composite design (CCD) experiments as follows: concentrated H2SO4 content, 6.6%; reaction temperature, 175 °C; reaction time, 30 min; and ratio of material to solvent, 1:4. The liquefaction yield and oil yield (chloroform phase) reached 93.85% and 37.96% under the above-mentioned conditions. The ultimate analysis and calorific value of the oil were determined, and the chemical composition of the oil was investigated using gas chromatography–mass spectrometry (GC-MS) techniques and Fourier-transform infrared (FT-IR) spectroscopy. The analysis of bio-oil composition showed that bio-oil from BC mainly contains ethyl palmitate, which is the main component of palm oil biodiesel, wi...

Seismic liquefaction performance of strip foundations: Effect of ground improvement dimensions

Evidence from field case studies, as well as from experimental and theoretical research, suggest that the detrimental effects of seismic liquefaction on the performance of surface foundations on level ground may be mitigated in presence of a non-liquefiable soil crust of adequate dimensions and shear strength. This paper refers to the case where the non-liquefiable crust is not natural, but it has been artificially created by ground improvement, and focuses upon the effect of the size (thickness and width) of the improved area on the seismic settlement and the degraded post-seismic bearing capacity of the foundation. Size effects are evaluated numerically, starting from the reference case of an infinitely extending improved soil crust and progressing to more realistic cases of ground improvement of gradually decreasing lateral extend of improved soil. Guidelines are provided for a cost-effective design of ground improvement, based on the rate of seismic settlement reduction with increasing dimensions of the improved ground.

Membrane-assisted CO2 Liquefaction: Performance Modelling of CO2 Capture from Flue Gas in Cement Production

CEMCAP is an international R&D project under the Horizon 2020 Programme preparing the ground for the large-scale implementation of CO2 capture in the European cement industry. This paper concerns the performance modeling of membrane-assisted CO2 liquefaction as a possible retrofit application for post combustion CO2 capture. For the relatively large CO2 concentrations that are typical for the flue gas in conventional cement kilns, it may be possible to capture CO2 by combining a single membrane unit for bulk separation and a CO2 liquefaction train in which the waste stream is recycled and mixed with the feed to the membrane system. The required membrane surface area is strongly correlated with the CO2 concentration in the cement kiln flue gas, as well as targeted CO2 recovery, pressure ratio across the membrane, membrane separation factor and CO2 permeance. Specifications for flue gas pre-conditioning and an overall techno-economic evaluation are planned to follow the evaluation of experimental results for membrane performance under realistic conditions, as well as for CO2 liquefaction performance.

Using GIS to measure the impact of the Canterbury earthquakes on house prices in Christchurch, NZ

PurposeCanterbury, New Zealand, experienced two significant earthquakes in 2010 and 2011 with a devastating impact on both houses and land. Negative media attention to the potential financial risks of living near or on the new Technical Category 3 (TC3) land or on land in a flood zone has fuelled the perception of uncertainty over the negative property price impacts. This research aims to determine if residents’ perceptions of the risks associated with various types of land zones (e.g. TC1, TC2 and TC3) are reflected in property prices.Design/methodology/approachThis research analyses sale price patterns and the relationship between sale prices and house characteristics before and after both earthquakes. A three-step approach was taken by applying: an average trend analysis, Geographic Information Systems’ (GIS) hotspot analysis to identify possible spatial differentiations between the before and after-effects of the earthquakes and hedonic modelling to quantify the effect of house characteristics on sale price while controlling for and comparing three land zones (TC1 to TC3).FindingsThe data suggest that average sale prices increased after both quakes in TC1 and TC2 in contrast to TC3 zones, while close to 8,000 structures were demolished in red zones from 2010-2013 (supply was reduced). The econometric modelling suggests that higher sale prices are achieved by: newer houses across all land zones and more recent sale agreements only in TC1 and TC2 zones. Other observations include the effect of certain exterior façade materials on sale prices on the overall data set and in the individual TC1 and TC3 zones. In conclusion, the results suggest that although caution might exist for the TC3 zone, the quality of the house can override the stigma attached to the TC3 zones.Research limitations/implicationsA confounding factor in the research was that approximately 7,800 homes were rezoned red and/or demolished between 2010 and 2013 changing the supply and demand balance. Further, banks and other lenders updated their requirements for new lending on properties in the Canterbury region, requiring a number of reports from professionals such as structural engineers, geotechnical engineers and valuers before any new lending would be approved. Additionally, immediately after the September and February earthquakes, there was a 21-day stand-down period for earthquake-cover in Canterbury and without adequate insurance cover banks would not advance mortgage money, causing a short-term slowdown in the residential property market.Practical/implicationsThe outcomes of this research will be of interest to government agencies tasked with assessing compensation for affected property owners. For example, the Earthquake Commission (EQC) developed a Diminution of Value Methodology for Increased Flooding Vulnerability that formed the basis of a High Court declaratory judgment decision in December 2014 that cleared the way for the EQC to start settling properties with increased flooding vulnerability. The EQC methodology was informed by the results of similar studies to this one, from around the world. Homeowners and rating valuers will also be interested in the results to understand how house prices have been affected by market perceptions towards earthquake damage, particularly in the worst-affected areas.Originality/valueThis study fills a research void regarding the price impacts of residents’ perceptions of the risks associated with various types of land zones that reflect the expected future liquefaction performance of the land.