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In this study, a small-scale natural gas liquefaction device was built to verify the feasibility of optimization results of the dual nitrogen expansion natural gas liquefaction process with pre-cooling. From the thermodynamics perspective, the feasibility of using R22 instead of propane as a pre-cooling refrigerant, and nitrogen instead of natural gas as the feed gas was verified. Furthermore, a genetic algorithm was used to optimize the operational parameters of the dual nitrogen expansion liquefaction process. The operational performance and adaptability of the process were evaluated based on sensitivity experiments. The experimental results revealed that the relative error of the key node parameters between the experimental and simulation results was within 10%. Moreover, the experimental device and liquefaction process had a relatively large processing capacity (approximately between 35% and 130%), which is suitable when gas field production attenuation is relatively fast. The experimental device was insensitive to the pressure and temperature of the feed gas, and exhibited excellent adaptability.

In the field of LNG simulation study, most optimization studies have concentrated on the LNG processes at steady-state simulation, and only a few studies have reported the dynamic simulation of the LNG process, which is closer to actual operating conditions. The main purpose of this study was to design a dynamic model of propane pre-cooling double nitrogen-expander LNG process based on an actual LNG plant, to investigate the dynamic behavior of this process, which had been considered suitable for FLNG process in previous studies. Furthermore, this is one of the first studies to verify the dynamic simulation of this process through the actual operation of an LNG plant. First, the dynamic models of the main equipment used in this process were developed. Second, a dynamic simulation of this process was performed, and the dynamic behaviour was investigated. Finally, to verify the accuracy of the dynamic simulation, different types of dynamic conditions were added to the simulation to investigate the behaviour of the process, including disturbances in the feed gas flow rate and shutting down of the propane system. Further, the dynamic responses and average errors between the experimental and simulated values were obtained and discussed. The results indicated that the two-stream heat exchange model can be used to replace the multi-stream heat exchange model for dynamic simulation, with the average error of dynamic simulation being under 10%, the control system can resolve the problem of excess cooling capacity and make the entire system run stably in the case of feed gas flow rate disturbance, the whole system returns to stability within 100 min in the case of the propane system shutdown. The results can provide feasible prediction and verification methods for the construction of large experimental and liquefaction production devices in the future.

The mal-distribution of gas and liquid is the critical issue that can lead to the heat transfer deterioration in plate-fin heat exchangers, especially when the sloshing exists for the floating liquefied natural gas system. The severe sloshing motions of the sea strongly influence the uniformity of the gas–liquid distribution in heat exchangers. In this paper, a new entrance configuration is proposed to allow the distributor to provide a uniform two-phase flow before the two different fluids were mixed. As a comparison, both the uniformity and sloshing resistance are analyzed on gas–liquid distribution performances for the conventional header and the present proposed structure. Both the steady-state and the sloshing motion conditions are numerically simulated by using a CFD software FLUENT. The results show that the effectiveness of the proposed gas–liquid distributors was confirmed and the new design can significantly improve the uniformity of the gas–liquid distribution and the sloshing resistance of heat exchangers.

Liquefaction process is one of the key technologies of offshore FLNG device and is charged by a few of the company’s patent protection. Due to the special offshore operating environment, the choice of FLNG liquefaction process is different from that of onshore. It is very important that FLNG liquefaction process suitable for the marine environment and the oil and gas properties of the South China Sea. In this paper, the static and dynamic performance of propane pre-cooling and dual nitrogen expansion liquefaction process with independent intellectual property rights have been verified by experiment loop simulation with small scale 2000m3/d and middle scale 20000m3/d. Dynamic simulation experimental measures for liquefying key devices such as cold box placed on the swing experiment platform and propane separation tank and the cold box between difference of liquid level changes, are used to verify offshore adaptability of the liquefaction process. Through the static experiments of a small experimental loop with the scale of 2000m3/d simulation considers the liquefaction rate of 93%, energy consumption 0.42kw.h/m3; Dynamic experimental results through the cold box placed on the swinging platform shows that the heat transfer performance of cold box is not affected when FLNG hull roll wave reached 3.6 degrees. The mid-scale experimental simulation of 20000m3/d show that the liquefaction process has the advantages of simple debugging process, convenient operation, quick shutdown and restart, flexible operation, good adaptability to offshore operating parameters, and can realize 3 sets of refrigeration cycles simulation. The propane pre-cooling and dual nitrogen expansion liquefaction process with independent intellectual property rights through the static and dynamic experiments of small and middle scale experimental loop, is verified to the characteristics of high liquefaction rate, low energy consumption and good offshore adaptability. The liquefaction process with independent intellectual property rights can be used to as one of FLNG facility key technologies to develop offshore gas field and faraway from onshore of the South China Sea.

This paper introduces the research advances on replacement of CH4 in Natural Gas Hydrates (NGHs) by use of CO2 and discusses the advantages and disadvantages of the method on the natural gas production from such hydrates. Firstly, the feasibility of replacement is proven from the points of view of kinetics and thermodynamics, and confirmed by experiments. Then, the latest progress in CH4 replacement experiments with gaseous CO2, liquid CO2 and CO2 emulsion are presented Moreover, the superiority of CO2 emulsion for replacement of CH4 is emphasized. The latest experiment progress on preparation of CO2 emulsions are introduced. Finally, the advancements in simulation research on replacement is introduced, and the deficiencies of the simulations are pointed. The factors influencing on the replacement with different forms of CO2 are analyzed and the optimum conditions for the replacement of CH4 in hydrated with different forms of CO2 is suggested.

As one of the most promising equipment for deep far sea gas field development, FLNG has been widespread concern in the engineering sector. Due to the characteristic of LNG, the sloshing of liquid tank in FLNG is inevitable. Therefore, the sloshing load of liquid tank is one of the hotspots in engineering and academic research. In this paper, in order to simulate the sloshing load of liquid tank in FLNG, a secondary development software is proposed based on the commercial software FLUENT. The simulation results agree well with previous experimental results. This shows the accuracy of the simulation of the software. In addition, the longitudinal and transverse section of LNG tank is analyzed. The results shows that different excitation frequencies and amplitudes great influence on the sloshing load of liquid tanks, different filling levels also have a certain influence. This will be used to estimate the size of sloshing load for the FLNG equipment which may encounter in the real sea condition, and have certain significance in practical engineering.Copyright © 2014 by ASME

As one aspect of flow assurance considerations, severe slugging control strategy in deepwater riser is related to the safety of production system, therefore it’s of great significance to the development of deepwater oil and gas field. This paper summarizes commonly used severe slugging control methods briefly, then takes certain deepwater oil and gas field as an example to introduce the method of software simulation for making severe slugging control strategy of deepwater riser. Firstly the model is built with basic information such as pipeline route, production profile and fluid composition. Data of typical years is used to simulate flowing conditions to determine whether it’s within slugging zone. To mitigate slugging conditions, choking, gas lift and choking& gas lift combined methods are chosen and simulated based on the oil and gas field characteristics, and according to the results gas lift is suggested as the best solution. Factors such as riser type, gas injection location, and flexible riser depth are analyzed for better gas lift efficiency. Finally hydrate formation risk related to severe slugging is analyzed and the slug catcher size is checked. Based on the introduced software simulation procedure, severe slugging control strategy is made, which will be valuable for deepwater flow assurance design and study.Copyright © 2014 by ASME

The current status of the FLNG research project is introduced in this paper. Primary focus is placed on the six key technical areas which have been addressed in the phase I of this project, i.e. liquefaction process, LNG tank sloshing, single point mooring system, LNG tank selection and arrangement, LNG offloading and FLNG risk assessment. Firstly, the selection and design of liquefaction process is presented. Based on the result of comparison with other liquefaction process, an optimized and patented propane pre-cooled nitrogen two-expander cycle process is proposed. Secondly, LNG tank sloshing is considered through numerical simulation and model test. Thirdly, single point mooring system is discussed and considered the impact of different ballast types of FLNG, Both internal turret and external turret are analyzed. Fourthly, a comparison of three commonly used types of LNG containment system is performed considering of both the system characteristics and technical competence in China. In addition, the arrangement of LNG tank is also considered in this paper. Fifthly, both side by side offloading and tandem offloading are discussed. It is pointed out that both types of offloading should be deeply studied in further for applicability for the specified environment condition in South China Sea. Finally, the FLNG risk assessment process and framework is established. Furthermore, a full scale quantitative risk analysis covering all the major hazards of FLNG will be studied in the phase II of the project. In addition to the six key technical areas, future works during phase II of this project in the next five years from 2011 are also proposed.

LNG FPSO (LNG Floating Production Storage and Offloading Unit), is a new exploitation technology of offshore gas field. Acid gas removal process is the key link of pretreatment process which is foremost to FLNG technology, and directly affects the normal operation of subsequent processes. In this paper, based on the experience of onshore acid gas removal process technology, MDEA and DEA mixed amine solvent method has been used in acid gas removal process of offshore demonstration gas field. With the chemical simulation software HYSYS, the simulation analysis of acid gas removal process is completed and the effects of key parameters are analyzed. Finally, the recommended ranges of key parameters are given. The research results give some guidance and reference for the research of offshore floating acid gas removal process.

The transportation of heavy or waxy crude oils presents some special design problems, which must take into account the requirements for the control of asphaltene deposition on interior surfaces of the pipeline. With the asphaltene deposition of the crude oils, the effective cross-sectional area or flow passage of the pipeline will be shrunken continuously, which influences their flow properties and threatens their safe transportation. Therefore, the influence of asphaltene deposition on their flow properties should be known well to safely design and operate the pipeline. The focus in this paper is on the asphaltene deposition rate and the influence of the asphaltene deposition on flow properties. Simulations of heavy crude oil flow in different structural pipelines after various deposition patterns are presented using 3D CFD. The flow velocity of heavy crude oil increases with the reduction of the effective cross-sectional area of the pipe, which leads to its vibration and shorter service life. In the other hand, pressure and temperature in the shrunken effective cross-sectional area decrease with the increase of velocity, intensifying the asphaltene deposition and transportation difficulty. While flow properties vary depending on deposition patterns, flow rates and the pipe geometry. So the influence of asphaltene deposition on flow properties in different structural pipelines with various deposition patterns is diverse. The impact of deposition in bending and reducer pipelines is greater than that in straight ones. And the impact in serious deposition pipelines is greater than that in slight deposition ones. So flow properties change drastically in bending and reducer pipelines with serious asphaltene deposition, leading to rapid blockage of the pipelines. The results of this paper can provide a guide for safe design and transportation of heavy crude oil pipeline.

// Zhouguang Wang 1 , Yan Huang 1 , Yi Cheng 1 , Yi Tan 1,2 , Fenzan Wu 1 , Jiamin Wu 1 , Hongxue Shi 1 , Hongyu Zhang 1 , Xichong Yu 1 , Hongchang Gao 1 , Li Lin 1 , Jun Cai 2 , Jinsan Zhang 1 , Xiaokun Li 1,2 , Lu Cai 1,2 and Jian Xiao 1 1 Chinese-American Research Institute for Diabetic Complications, School of Pharmaceutical Science, Key Laboratory of Biotechnology and Pharmaceutical Engineering, Wenzhou Medical University, Wenzhou, Zhejiang, China 2 Department of Pediatrics, Children’s Hospital Research Institute, the University of Louisville, Louisville, Kentucky, USA Correspondence to: Jian Xiao, email: // Lu Cai, email: // Keywords : ER stress, inflammation, apoptosis, p-JNK, diabetes Received : June 09, 2016 Accepted : October 19, 2016 Published : October 26, 2016 Abstract We assumed that diabetic encephalopathy (DEP) may be induced by endoplasmic reticulum (ER)-mediated inflammation and apoptosis in central nervous system. To test this notion, here we investigated the neuronal ER stress and associated inflammation and apoptosis in a type 2 diabetes model induced with high-fat diet/streptozotocin in Sprague-Dawley rats. Elevated expressions of ER stress markers, including glucose-regulated protein 78 (GRP78), activating transcription factor-6 (ATF-6), X-box binding protein-1 (XBP-1), and C/EBP homologous protein, and phosphor-Jun N-terminal kinase (p-JNK) were evident in the hippocampus CA1 of diabetic rats. These changes were also accompanied with the activation of NF-κB and the increased levels of inflammatory cytokines, tumor necrosis factor-α (TNF-α) and Interleukin-6 (IL-6). Mechanistic study with in vitro cultured hippocampus neurons exposed to high glucose (HG), which induced a diabetes-like effects, shown by increased ER stress, JNK and NF-κB activation, and inflammatory response. Inhibition of ER stress by 4-phenylbutyrate (4-PBA) or blockade of JNK activity by specific inhibitor or transfection of DN-JNK attenuated HG-induced inflammation and associated apoptosis. To validate the in vitro finding, in vivo application of 4-PBA resulted in a significant reduction of diabetes-induced neuronal ER stress, inflammation and cell death, leading to the prevention of DEP. These results suggest that diabetes-induced neuronal ER stress plays the critical role for diabetes-induced neuronal inflammation and cell death, leading to the development of DEP.