The rapid induction of Fiber Reinforced Plastics (FRP) into process industry due to high corrosion resistance and cost effectiveness made End Users to overlook FRP's specific design, fabrication and quality control aspects. This also affected various Utility and firewater networks in ADNOC Gas Processing plants. It is addressed by enhancing Vendor pre-qualification, relevant specifications and construction procedures. This paper presents measures adopted to ensure reliable design, supply and installation of FRP piping systems.
FRP piping systems have unique design/construction requirements that was not followed in totality in AGP past installations. Also, international standards do not offer adequate guidance on design, resins selection, fabrication methods and joint systems. Vendors were trusted upon for complete design. A campaign is initiated to engage FRP pipe manufacturer having binding single point responsibility from beginning of project for particular FRP system design to ensure desired performance of FRP piping system with extended warranty. Measures have been taken to improve quality material supply through enhanced vendor pre-qualification, ADNOC Gas Processing specifications and CONTRACTORS pre-qualification having certified site crew.
Studies revealed that material quality, velocity/surge pressure were the main contributing factors for failures which were not adequately addressed in design of FRP piping systems. Gaps noticed in previous projects were use of inadequate Codes, Composite's mechanical properties, design approach, inadequate joint preparation and QA/QC in construction phase. During manufacturing using wrong resin can be a cause for premature failure. Absence of certified personnel for project execution and
Non-compliance of manufacturer's instructions were also key lapses noted in construction phase. The gaps in design process, necessitated improvement and consolidation of ADNOC Gas Processing existing design specifications/criteria and analysis requirements which now mandate that the required hydraulic / surge / static analysis shall be carried out by pre-qualified FRP manufacturer. Material property issues were addressed by clearly specifying the material composition & properties requirements and procedural requirements for storage are incorporated into the manufacturing process, along with mandating minimum prior experience for the manufacturers for material supply and design. Certification of contractor's personnel and presence of FRP manufacturer's representative at site during construction and pre-commissioning has been emphasized as mandatory requirement. In addition Specialist 3rd party inspection/supervision must be deployed to ensure quality control during every step of construction and commissioning
Design specifications, procedures, manufacturing process, QA/QC and installation methods for FRP piping systems are available, but lacked activity interface between consultant, vendor and contractor. ADNOC Gas Processing enhanced the FRP specification ensuring single point responsibility with Vendor and procedures to ensure consistency from the design phase coherent with manufacturing process and appropriate implementation during the execution phase, in order to ensure the safety and integrity of FRP Piping systems.
Acid Gas Recovery Units (AGRUs) are one of the core and energy intensive units in gas processing. In solvent based AGRUs, the rich solvent leaving absorber column is letdown across control valve before being sent to flash vessel. This pressure letdown indicates opportunity to recover energy by utilizing hydraulic turbine. In this context, an in-house study has been carried out to evaluate techno-economic feasibility of recovering energy from four (04) amine based AGRUs at one of the gas processing sites. Pressure letdown, across amine absorber control valves at selected AGRUs, from 60 to 7 barg indicated significant potential for energy recovery. A comprehensive review of existing design and current operation of AGRUs was carried out by technical team in close co-ordination with site personnel. Design inputs were prepared after discussions with Operations and Technical Services teams to evaluate modifications needed to implement the Hydraulic Power Recovery Turbine (HPRT). Internal estimation of potential power recovery was prepared and modifications needed to develop scope definition were identified. The team consulted potential suppliers for new equipment and technical proposals were evaluated for technical feasibility after discussions with multidisciplinary engineering teams.
The key challenges relate to the feasibility of modification given the brownfield modifications, as the piping routing with existing arrangement of equipment like HP absorber, lean gas circulating pump and rich amine flash vessel etc., could lead to potential constraints of space availability and pipe-rack adequacy. In addition, competent contractors are required to implement modifications to existing lean amine circulating pump as shaft modifications are needed. Efficiency of hydraulic power recovery turbine and performance guarantees signifies the successful implementation. Overall cost, economic feasibility over its lifecycle and schedule for implementation are few of the the major factors governing the management decision.
Based on current operation, preliminary estimates indicated power recovery potential of the order of around 5MW, from the four (04) AGRUs considered in the study, duly considering the overall efficiency of HPRT. The study ascertained significant reduction in power consumption of lean amine circulating pumps by utilization of recovered hydraulic power from respective AGRUs. Economic feasibility observed sensitive to applicable power tariff and other financial basis. However, on overall basis, study established that HPRT technology represent reliable, economically feasible solutions to reduce power consumption and emissions, thereby improving energy efficiency of gas processing industry.
Albraiki, Ahmed (ADNOC Gas Processing) | Al Ahmad, Alya (ADNOC Gas Processing) | Al Awadhi, Ibrahim (ADNOC Gas Processing) | Kant Nath, Nahum (ADNOC Gas Processing) | Mohamed Ismail, Mohamed Sulaiman (ADNOC Gas Processing)
ADNOC Gas Processing (AGP) plays a strategic role in ADNOC and the UAE hydrocarbon value chain by contributing significantly for the development of the Emirates. AGP operates and manages an integrated Pipeline Network of approximately 3200km length of Pipelines with the mission of uninterrupted supply to its Customers without any impact on the upstream plants. Various fluids are transported via pipelines such as Sales gas, Crude oil, NGL, Condensate, Water, Nitrogen and associated gases wherein majority of network contains Sales Gas. Pipeline Network is scattered over Ruwais, Habshan, Buhasa, Asab, Shuwaihat, Jebel Danna, Al Maqta, Taweelah, Jebel Ali, Al Ain, Ghantoot, Al Dhabbaya, Al Romaitha, Saadiyat Island, Yas Island, Mussafah and in some other areas within the Emirate of Abu Dhabi.
The Sales gas pipeline network connects gas plant facilities to consumers/ADNOC Plants through pipeline Distribution Facilities (Manifolds). The NGL pipeline network connects NGL plant facilities with manifolds to onward supply of NGL to AGP plant for fractionation into various products such as ethane, butane, propane and naptha etc.
These manifolds are old and highly critical, hence their safety and reliability are paramount to ensure shareholders commitment to various consumers in UAE and abroad. Failure of these manifolds will have a major impact on upstream & downstream production chain. Shut down of these manifolds are not possible as there is no bypass arrangement or back up manifold for business continuity. Failure of any of the manifold will have major impact on AGP Business and reputation.
Some of theses manifolds were constructed in late 70’s and have completed their design life. In line with current business scenario and fit for purpose approach being adopted by ADNOC, it is prudent to understand methods to assess the condition of existing ageing assets and apply techniques to enhance the reliability and integrity of the same. Ageing equipment is challenging and a systematic approach is necessary to decide on the life of ageing assets. AGP is one of the largest gas processing companies in the world, and it is considered as the major energy and feedstock supplier for the majority of the power, hydro carbon, and petrochemical industries based in the UAE.
In view of the above, AGP has carried out an Integrity/Adequacy assessment study to check fitness for service of the manifolds with due consideration to business continuity, the impact on upstream/downstream production, Company reputation, asset integrity, process safety and HSE aspects etc.
This paper presents the challenges faced and best practices adopted for ensuring/enhancing Process Safety (Prevention of Loss of Containment), improve integrity/reliability of the manifolds, minimize impact on normal operation and maintenance and reduce the risk of business interruption.
AGP best practices are based on the requirements of Pipeline Codes, International Standards, industry practices, ADNOC Gas Processing Specifications/Standards, and good engineering practices etc.
The Best Practices followed in this study have ensured the safety, efficiently and reliablty of operation of these manifolds. Confidence level in assuring integrity of againg facilities is boosted. Similar approach will benefit the oil and gas industries for ensuring safety and integrity of old ageing facilities.
Electrical utilities are subject to voltage sags, poor power factor and even voltage instability as long as it suffers from shortage of its reactive power sources. The only mitigation to this problem is to have proper and fast acting reactive power control on the grid. This in turn will overcome the major concerns of network voltage instability, especially during the transient and sub-transients conditions such as major switching operation, and electrical faults. In many cases, the traditional solutions of switching capacitors is too coarse and slow to stabilize a weak network. The most advanced solution to compensate reactive power is to incorporate a STATCOM (or Static Synchronous Compensator) as a variable source of reactive power. STATCOM is an advanced power electronic system for fast capacitive/inductive reactive power supply providing reactive power compensation and, steady state and transient voltage stability, etc… These systems offer advantages compared to standard reactive power compensation solutions in demanding applications. In order to mitigate utility network power quality problems, ADNOC Gas Processing has recently introduced a STATCOM solution in two running plants. This paper deals with the design process of customized Power Quality solutions involving STATCOM Technology to resolve network quality issue up to full commissioning of the system, elaborate on challenges and difficulties faced, and highlight how it was resolved.
Expansion / Debottlenecking of Industrial or Oil & Gas plants is a common phenomenon and many a times such expansion has to be located within limited plot boundaries posing multiple challenges in locating the equipment and design & execution of supporting civil structures. In some cases, finalized supporting civil structures are not feasible to implement due to additional challenges such as additional underground utilities not identified in as-built survey that may arise during execution stage affecting project schedule. Generally, such unique design challenges are not encountered in Greenfield project development. This paper presents the typical constraints encountered in expansion projects, key parameters required to finalize the innovative solutions and measures / methods adopted to overcome the constraints in most effective and economical way in one of the major brownfield project without affecting safe functioning of existing plant. Vibration transmissibility to structures / equipment from new equipment or old equipment vice versa, physical constraints in supporting / routing new piping, underground utilities present in the plot are some of the major challenges faced during detail engineering.
A localized tube rupture was observed in the convection section of Fired heater. To address this, improve Integrity and avoid Process Safety concerns, the existing convection section required replacement. This paper presents an alternate approach followed to reduce operating costs by enhancing the heater performance and efficiency while addressing high heat flux issue.
The new convection section was designed with an increased coil surface area to enhance the heat recovery and optimize heat flux. Fin materials were changed from original carbon steel to SS410 in high temperature zone to minimize fin burn-off issues. The challenges were phenomenal, as the heater was 40 years old and new convection section is twice heavy and size than existing. In order to overcome, systematic engineering approach was adopted, from sizing new convection section with optimum heat flux, Mechanical design with FEA to verify structure integrity and foundation adequacy for increased loads. As a step toward safeguarding the tube from similar future failure, tube skin thermocouples were installed in shield tubes to facilitate continuous monitoring.
Analysis confirmed integrity of the heater with minimum modification on anchor bolt avoiding need major foundation and structural upgrade. Two furnaces have been upgraded with new convection section and continuous monitoring for period more than 1 year has confirmed performance with no tube failure ensuring 100% HSE. Post project implementation resulted in more heat recovery from flue gases due to increased. Flue gas temperature leaving convection section was reduced from 450°C to 220°C. Consequently, required fuel gas consumption was reduced considerably by 9031 MT per year for two heaters. In conclusion, similar reductions in fuel gas consumption can be achieved over the equipment's extended service life.
The implementation has led to not only to increase in heater efficiency but in turn improved the heater duty for same burner capacity, there by supporting increase in plant throughput.
Conventional approach of replacing tube with improved metallurgy would have ensured process safety and structural integrity. However, the synchronized and pre-emptive engineering approach has yielded multiple benefits for the rest of the heater as well plant operational life. This also led to improved efficiency and Optimum Energy Conservation and save operating cost up to almost 1.1Million USD/year. Even a leak can lead us to peak if the opportunity is harvested in right way.
TechnipFMC was appointed by one its major client to conduct a feasibility study for the development a highly sour gas-condensate field. Sour gas levels are in the range of 22-28%vol of H2S and 13-17%vol of CO2 and contains also organic sulphur components such as carbonyl sulphide, mercaptans and disulphides.
The study addresses the evaluation of onshore technologies for gas and condensate processing (gas sweetening, gas dehydration, NGL recovery, condensate stabilization and sweetening) for five different set of export product: sales gas, LPGs, hydrocarbon condensates, Sulphur or re-injection of the acid gases, with the objective of selecting the most attractive scheme based on economic and HSE criteria.
Using this case study, this paper aims to present the methodology, the different process configuration screened, the pros and cons of each technology, and the influence of basic technico-economic parameters on the plant architecture and technology selection.
Dara, Satyadileep (ADNOC Gas Processing) | AlWahedi, Yasser (Khalifa University) | Berrouk, Abdallah (Khalifa University) | Leyland, Simon (Process Systems Enterprise) | El Nasr, Adel (ADNOC Gas Processing) | Khan, Ibrahim (ADNOC Gas Processing) | Geuzebroek, Frank (ADNOC Gas Processing)
This study aims at high-fidelity modeling and mechanistic optimization of gas dehydration and NGL (Natural Gas Liquids) systems of a commercial natural gas plant based in Abu Dhabi, UAE. Scope of the work includes development of models, validation of models with plant data, optimization analysis and real-time validation at the plant site.
In this work, we developed a dynamic model for the gas dehydration system and a steady state model for the natural gas liquids recovery unit. An advanced process simulator that follows equation-oriented approach is employed as the modelling and optimization platform. We first show the comprehensive plant data reconciliation followed by the model validation using the operating data of the years 2016 and 2018, to ensure that the model predictions match the real plant operation. We then present how the mechanistic optimization entity result in the best operating conditions for the natural gas liquids recovery system. We also show the optimization analysis that aims at maximizing the adsorption cycle time for the dehydration unit while minimizing the total heating duty required for the regeneration of the molecular sieve beds.
Optimization analysis reveals a significant increase in the annual net revenue of natural gas liquid recovery unit as a result of modifying various process operating conditions that lead to higher liquid hydrocarbon production and lower operating costs related to steam and refrigeration. Similarly, optimization analysis of the dehydration system indicates that adsorption-step time can be increased to a higher value, which results in significant reduction of regeneration costs.
As a next step, we aim to carry out the validation tests on the plant site to verify and implement the model recommendations in the real plant to verify the model recommendations. We also plan to derive the set of operating guidelines that allow the operators to drive the plant towards optimal operation.
To the best knowledge of authors, this study is the first effort to build a holistic model comprising of the dynamic dehydration model and steady state NGL model on a common platform.
Rigorous validation of the model is performed using real plant data of two calendar years.
Scope of this study also includes real time validation of the model recommendations through tests performed at plant site.
To explore the opportunity for maximum utilization for one of gas processing facilities in line with ADNOC strategy to enhance profitability and asset utilization. A Technical study was conducted to increase the processing capacity up to 115% of its design limit. This was to identify the potential bottlenecks in the facility and suggest debottlenecking options with a reasonable investment.
The objective of the study was to assess monetization opportunity in existing gas processing facilities by recovering CO2 from the acid gas stream and utilizing it to enhance oil recovery. This could potentially lead to generating more revenues with minimum modifications and optimizing the plot footprint, energy, and overall cost, all while maintaining business continuity.
The Study was conducted in two stages:
The final selected concept for CO2 capture was as per followings:
Low pressure chemical solvent type CO2 capture Unit located downstream of the AGRU but upstream of the flash / recovered flare gas tie in; Wet CO2 compression to TEG dehydration unit and dry CO2 compression transport for injection; Reinject enriched H2S from the CO2 capture unit to condensate reservoir The selected concept UTC US$ / MT of CO2 compared by performing similar exercises for other two sites and it is observed that UTC varies depending on existing process and utilities systems configuration, feed gas quality and product specifications.
Low pressure chemical solvent type CO2 capture Unit located downstream of the AGRU but upstream of the flash / recovered flare gas tie in;
Wet CO2 compression to TEG dehydration unit and dry CO2 compression transport for injection;
Reinject enriched H2S from the CO2 capture unit to condensate reservoir
The selected concept UTC US$ / MT of CO2 compared by performing similar exercises for other two sites and it is observed that UTC varies depending on existing process and utilities systems configuration, feed gas quality and product specifications.
This concept can potentially be enhanced by taking calculated risks and applying emerging technologies with Licensors’ to ease UTC from its current level and complement other by-products to enhance overall value chain in energy sector. In addition to that this, UAE has set the National Climate Change Plan 2017–2050 that serves as a roadmap to boost nationwide actions for climate mitigation. Capturing CO2 for EOR economically will facilitate UAE to minimize carbon emission footprint.
Based on aforementioned Pre-FEED study, this paper identifies and evaluates the most viable options for the CO2 capture unit location, CO2 capture technology, CO2 dehydration and transport technology and H2S handling for the entire operating envelope. This paper also provides an overview of the CO2 dehydration unit optimum operating pressure, discussions on CO2 wet and dry compressors and the configuration of the CO2 capture train(s).