Improving the profitability, availability and condition monitoring of FPSO terminals

The main focus of this study is to improve the profitability, availability and condition monitoring of Liquefied Natural Gas (LNG) Floating Production Storage and Offloading platforms (FPSOs). Propane pre-cooled, mixed refrigerant (C3MR) liquefaction is the key process in the production of LNG on FPSOs. LNG liquefaction system equipment has the highest failure rates among the other FPSO equipment, and thus the highest maintenance cost. Improvements in the profitability, availability and condition monitoring were made in two ways: firstly, by making recommendations for the use of redundancy in order to improve system reliability (and hence availability); and secondly, by developing an effective condition-monitoring algorithm that can be used as part of a condition-based maintenance system. C3MR liquefaction system reliability modelling was undertaken using the time-dependent Markov approach. Four different system options were studied, with varying degrees of redundancy. The results of the reliability analysis indicated that the introduction of a standby liquefaction system could be the best option for liquefaction plants in terms of reliability, availability and profitability; this is because the annual profits of medium-sized FPSOs (3MTPA) were estimated to increase by approximately US$296 million, rising from about US$1,190 million to US$1,485.98 million, if redundancy were implemented. The cost-benefit analysis results were based on the average LNG prices (US$500/ton) in 2013 and 2014. Typically, centrifugal turbines, compressors and blowers are the main items of equipment in LNG liquefaction plants. Because centrifugal equipment tops the FPSO equipment failure list, a Condition Monitoring (CM) system for such equipment was proposed and tested to reduce maintenance and shutdown costs, and also to reduce flaring. The proposed CM system was based on a novel FFT-based segmentation, feature selection and fault identification algorithm. A 20 HP industrial air compressor system with a rotational speed of 15,650 RPM was utilised to experimentally emulate five different typical centrifugal equipment machine conditions in the laboratory; this involved training and testing the proposed algorithm with a total of 105 datasets. The fault diagnosis performance of the algorithm was compared with other methods, namely standard FFT classifiers and Neural Network. A sensitivity analysis was performed in order to determine the effect of the time length and position of the signals on the diagnostic performance of the proposed fault identification algorithm. The algorithm was also checked for its ability to identify machine degradation using datasets for which the algorithm was not trained. Moreover, a characterisation table that prioritises the different fault detection techniques and signal features for the diagnosis of centrifugal equipment faults, was introduced to determine the best fault identification technique and signal feature. The results suggested that the proposed automated feature selection and fault identification algorithm is effective and competitive as it yielded a fault identification performance of 100% in 3.5 seconds only in comparison to 57.2 seconds for NN. The sensitivity analysis showed that the algorithm is robust as its fault identification performance was affected by neither the time length nor the position of signals. The characterisation study demonstrated the effectiveness of the AE spectral feature technique over the fault identification techniques and signal features tested in the course of diagnosing centrifugal equipment faults. Moreover, the algorithm performed well in the identification of machine degradation. In summary, the results of this study indicate that the proposed two-pronged approach has the potential to yield a highly reliable LNG liquefaction system with significantly improved availability and profitability profiles

Profitability, reliability and condition based monitoring of LNG floating platforms: a review

The efficiency and profitability of Floating, Production, Storage and Offloading platform (FPSO) terminals depends on various factors such as LNG liquefaction process type, system reliability and maintenance approach. This review is organized along the following research questions: (i) what are the economic benefit of FPSO and how does the liquefaction process type affect its profitability profile?, (ii) how to improve the reliability of the liquefaction system as key section? and finally (iii) what are the major CBM techniques applied on FPSO. The paper concluded the literature and identified the research shortcomings in order to improve profitability, efficiency and availability of FPSOs

Ryan-Holmes and modified Ryan-Holmes processes for LNG production

The objective of this research was to evaluate various process alternatives for the production LNG (Liquefied Natural Gas) from natural gas feeds with significant CO2 levels, typical of some of the Australian gas reserves. It is believed that the conventional amine process which is commonly utilized for treating sour natural gas may be energy-intensive, particularly if CO2 produced must be sequestrated. Consequently, two different alternatives to the amine process were investigated, which were based on the Ryan-Holmes (RH) process with one of them also using membrane in addition to distillation columns

Biogas Utilization Opportunities in Ostrobothnia Region : findings from the project

This final report summarizes the key results of the "Biogas Utilization Opportunities in Ostrobothnia Region" project, which was conducted from March 2020 - September 2022 by the University of Vaasa. Reducing greenhouse gas emissions to the atmosphere, replacing fossil fuels with renewable fuels, and reducing waste play a key role in the EU's climate recycling targets. Biogas has a vital role to play in achieving these goals. However, the utilization of biogas in Finland is still limited, and it can be stated that the biogas market and the infrastructure enabling the market operation are still developing. The overall goal of this project was to build new knowledge and create favorable conditions for biogas business and biogas use to grow through techno-economic studies, measurements, and common operation models. Screening of real-driving emissions of a biogas-fueled city bus and the well-to-wheels analysis showed that up to 90 % greenhouse gas emission savings could be achieved by switching from liquid fossil fuel to biomethane. In addition to the biogas use as a traffic fuel, we investigated the possibilities of industrial operators and the local energy sector to switch to renewable biogas in their operations. To make biogas a realistic alternative for them and other potential new end-users – such as heavy transport and the maritime sector – the production and supply of liquefied biomethane, in particular, needs to be increased. Investments in local biogas liquefaction and a regional biogas pipeline could be the next major step in promoting biogas use in Ostrobothnia. The greenhouse industry could contribute with biomass waste material to biogas production. Biogas could in return also be employed in combined heat and power applications in greenhouse operations. Nonetheless, the greenhouse industry is already utilizing a lot of other bioenergy in heating. Carbon dioxide capture at biogas production plants is technically possible, and appears to be or become implemented at several sites in Europe. In the project, three biogas scenarios were created for Ostrobothnia, based on the findings from literature, interviews, and workshops as well as the project’s own calculations. The future direction of biogas solutions in Ostrobothnia is still unclear due to legislative issues, investment costs, and lack of knowledge. With sufficient support, the biogas sector can be expected to grow considerably.fi=vertaisarvioimaton|en=nonPeerReviewed

계층구조절차와 MILP 기반의 도미노효과를 고려하는 육상과 해상에서의 화학공정 최적배치에 관한 연구

학위논문 (박사)-- 서울대학교 대학원 : 화학생물공학부, 2014. 8. 윤인섭.This thesis presents optimal layout generation and its application considering the method of criteria application to prevent accident propagation and the structural stability in the offshore plant. In the chemical plant, fire and explosion accidents occur because of the harsh operation condition and hazardous materials. Sometimes these accidents can be expanded to disaster by damage to human or properties. Thus, the risks of the chemical plant have to be considered from the design step. The developing location of the buried energy is also moving farther away from inland, and the offshore platform is spotlighted and studied more for exploitation and the corresponding safety improvement. The objective of this thesis is to propose a new method to determine the optimal layout preventing the chain reaction of accidents called domino effects and considering the stability of offshore platform. In this thesis, the methodology is suggested to improve the safety by proposing the mathematical programming-based procedure using MILP model. Also, the hierarchy procedures including main factors to be considered, which can be applied to the on/offshore plants, are suggested. The proposed methodology is verified by applications to practical case studies, which are being used or will be adopted in the onshore and offshore industries, such as the ethylene oxide production process as an onshore process in the chemical industry, the top-side of CO2 carrier as a single-floor offshore plant to be used in the Korea, and the mixed refrigerant cycle of the LNG liquefaction system on the top-side of LNG-FPSO as multi-floor offshore process for gathering the energy. Before the determination of the optimal layout, the distance related to the risks in the process is calculated from quantitative risk assessment to estimate the effects of possible accidents. In case of offshore platform, considering the structural constraints, overall weight balance is added to satisfy the proposed criteria for stability of the whole plant and it would be beneficial to select the proper distribution of equipment. The results of the case studies showed satisfying the proposed risk criteria for preventing the domino effects between the equipment under the given constraints. The suggested method in this thesis contributes to helping the systematic determination of sustainable layout of chemical processes by reducing the damage to equipment and increasing structural stability of the offshore platform.Abstract i Table of Contents v 1 Introduction 1 1.1 Research scope 3 1.2 Thesis outline 4 2 Backgrounds 6 2.1 Domino effects 6 2.2 Risk identification 7 2.2.1 Hazard and operability (HAZOP) study 8 2.2.2 HazopNaviTM 11 2.3 Quantitative risk assessment (QRA) in the chemical process 12 2.4 Layout optimization – review of mathematical approach 28 3 Safety issues in the offshore plant 30 3.1 Considerations in the design stage 30 3.2 Considerations in the layout stage 34 4 Proposed layout optimization 37 4.1 Hierarchy procedure for optimal layout 37 4.2 Overall framework 40 4.3 Mathematical models 43 4.3.1 Objective function 43 4.3.2 Distance constraints 44 4.3.3 Weight balance constraint 52 4.3.4 Protective device 55 4.3.5 Other constraints for multi-floor 55 5 Case Studies 57 5.1 Onshore plant – ethylene oxide plant 57 5.1.1 Process description 58 5.1.2 Results of risk analysis 61 5.1.3 Results of layout optimization 67 5.1.4 Summary and discussion 78 5.2 Offshore plant – CO2 liquefaction process on CO2 carrier 80 5.2.1 Process description 82 5.2.2 Results of risk analysis 87 5.2.3 Results of layout optimization 94 5.2.4 Summary and discussion 104 5.3 Offshore plant – LNG-liquefaction system in the LNG-FPSO (multi-floor) 107 5.3.1 Process description 108 5.3.2 Results of risk analysis 115 5.3.3 Results of layout optimization 118 5.3.4 Summary and discussion 131 6 Conclusion 134 Nomenclatures 137 References 138 초 록Docto