High Production Well Operating Plant in a Traditional Design: Piping & Instrumentation Challenges

During the exploration design phase of recent pre-salt development in Santos Basin, it was identified great potential for the production of some wells, generating great expectation by how it would perform in the production phase, above the average of 30,000 bpd. The Subsea and Topside design were developed based on this expectation and therefore, diameters were limited considering the premises of 45,000 bpd production from the well to the FPSO. As a result of first oil production the expectation not only became a reality but also was largely supersede, confirming a very high production potential of up to 65,000 bpd per well, some of which are at the world top list of highest production wells for deep and ultra-deep waters. Despite the outstanding high potential of the well, full production was then, not able to be achieved due to limitations considered in the design's premises of 45,000 bpd per well, what overcome the already great expectation. In this scenario, there was intense effort to make the real production potential of the wells viable. To fit the design to the new dynamic flow conditions, a multidisciplinary technical assessment team was mobilized involving several disciplines such as: Subsea Equipment, Wells, Risers, Process, Piping, Instrumentation and Automation, in addition to Operational Safety, a non-negotiable value. After technical discussions between those different disciplines, alternative proposals were raised that could make possible a safe operation under this new challenging condition. The defined actions were implemented and currently the wells already operate on high levels of production. On the FPSO with those high production wells, due to this individual increase in the production, whose potentials exceed by 45% the design capacity, generating a significant increase in the profitability of the asset, contributing to revenues anticipation in the company's cash flow. This article presents the piping and instrumentation study to deal with a high flow velocity issue. The methodology adopted to overcome the challenges in vibration and erosion considered an unusual design approach, leading to some field test to check the effectiveness of the solution. This alternative approach allowed this increment in production rate per well piping branch.

Model development and control of an auto-refrigerated polystyrene polymerization reactor

Dynamic model development and control of an existing operating industrial continuous bulk free radical styrene polymerization process are carried out to evaluate the performance of auto-refrigerated CSTRs (continuous stirred tank reactors). One of the most difficult tasks in polymerization processes is to control the high viscosity reactor contents and heat removal. In this study, temperature control of an auto-refrigerated CSTR is carried out using an alternative control scheme which makes use of a vacuum system connected to the condenser and has not been addressed in the literature (i.e. to the best of our knowledge). The developed model is then verified using some experimental data of the real operating plant. To show the heat removal potential of this control scheme, a common control strategy used in some previous studies is also simulated. Simulation results show a faster dynamics and superior performance of the first control scheme which is already implemented in our operating plant. Besides, a nonlinear model predictive control (NMPC) is developed for the polymerization process under study to provide a better temperature control while satisfying the input/output and the heat exchanger capacity constraints on the heat removal. Then, a comparison has been also made with the conventional proportional-integral (PI) controller utilizing some common tuning rules. Some robustness and stability analyses of the control schemes investigated are also provided through some simulations. Simulation results clearly show the superiority of the NMPC strategy from all aspects.

NEW METHOD EVALUATION OF DETAIL MATERIAL AND HEAT FLOWS FOR SINGLE STRING CEMENT CLINKER PLANT

Material flow in each main equipment of a cement clinker plant, which is very useful for controlling the process, is impossible to be measured during operation due to very high temperatures. This paper intends to overcome the difficulties associated with the measurement of these material flow values. This study presents a new method of calculating material flow (gas and solid) in each main equipment of a single string conventional suspension preheater type of a cement clinker plant. Using the proposed method, mass flow rate at a clinker cooler, kiln, suspension preheater (SP) and even each cyclone separator can be calculated with a heat conservation error less than 1 %. With the application of the least square method for solving the overdetermined system of mass and heat conservation equations obtained in the cyclones of SP, the flow of gas and solid materials entering and exiting each cyclone that cannot be measured directly in the operating plant can be approached. Based on the operation temperature data of gas and solid flows monitored in the control room of an Indonesian cement plant as a case study, the mass flow rate of gas and solid entering and exiting as well as separation efficiency of each cyclone can be calculated. The results show that the separation efficiencies of cyclones 1, 2, 3 and 4 are 95 %, 91.89 %, 84.09% and 79.51% respectively. Finally, this study will be very useful by providing data that are impossible to gather by a direct measurement in an operating plant, due to a very high process temperature constraint, for operational control needs, new equipment design, process simulation using computational fluid dynamics (CFD) software and even modification of existing equipment. The proposed method can be applied to all types of modern cement clinker plant configurations, either with or without a calciner including the double strings.

Optimizing for Viability – Revamping Vacuum Distillation Unit in a Brownfield Project

Revamping an existing column in an operating plant for a higher throughput is always a challenge especially when the column is already operating at its rated capacity. This is particularly true for a Vacuum Distillation Unit (VDU) column which involves multiple product and pump-around streams and associated auxiliary units like a steam ejector system. Optimizing the design and operation of the column, hence, is inevitable to ensure the viability of a brownfield project as it avoids major modifications required to the column and its associated auxiliary systems. This paper discusses how optimization was done on the design and operation of an existing VDU column in an oil refinery, avoiding major modifications of the associated ejector, steam, cooling water, sour water systems and heat exchanger network, allowing a brownfield project to stay commercially viable.

A Code Case Concerning the Effect of Embrittlement on Index Temperature Metrics

The ASME Section XI Working Groups on Operating Plant Criteria (WGOPC) and on Flaw Evaluation (WGFE) have undertaken an effort to develop a new Code Case (Record # 19-1113) to address the following inquiry: What method(s) are acceptable for obtaining RTNDT, RTTo and/or T0 that account for embrittlement for analytical evaluations performed in accordance with Nonmandatory Appendices A, E, G, or K in lieu of the current requirements of these Appendices? Accounting for embrittlement in Code calculations in an appropriate manner is a critical element to the operating safety of nuclear power plants. The intent of responding to this inquiry is to ensure that Code guidance on this matter is comprehensive, up-to-date with the current state of knowledge and applications, and appropriate for international use. The work on the Code Case aims to unify guidance on the following topics throughout the Code, and to fill gaps as needed: • Source of embrittlement data, • Forecasting of embrittlement trends, • Accounting for embrittlement in the inter-relationships between various toughness properties, and • Accounting for uncertainties associated with embrittlement. This paper outlines the overall structure of the Code Case, and summarizes the progress achieved to date.

The Non-Effect of Yield Strength on RTT0 and on the Master Curve

During the August 2018 ASME Committee Week, a Code Change Inquiry was presented to the Working Group on Operating Plant Criteria (WGOPC): Question 1: Is it the intent of G-2110 to limit RTT0 use to ferritic materials with specified minimum room temperature yield strengths 50 ksi or less? Question 2: If the reply to Question 1 is “No”, is it the intent of G-2110 that G-2110(b) requirement must be met before RTT0 may be used for ferritic materials above 50 ksi but not exceeding 90 ksi? During that meeting the WGOPC replied “no” to both questions. This paper provides an evaluation of available fracture toughness data augmented by an understanding of the underlying mechanisms of cleavage fracture to demonstrate the veracity of the WGOPC’s answer with regards to RTT0 and, more generally, with respect to the Master Curve.

Geometallurgical Studies on Gold Ore for Enhanced Comminution and Leaching

Many gold processing plants are experiencing challenges as mining pits are becoming deeper, rocks are getting harder and more complex polymetallic and refractory ores are being encountered. The variations in the characteristics of ores lead to deviations from the established parameters, and these affect gold extraction efficiency. This paper presents a study where geological characteristics of the ore types from some mining pits were used to ascertain the influence of ore blends on improving the performances of comminution and leaching circuits. To achieve this, mineralogical, comminution, gravity recoverable gold and leaching investigations were conducted on fresh and weathered ore samples and their blends. Mineralogical study showed that the main rock types associated with the mine pits were dolerite, phyllites, conglomerates and sandstone. The dominant minerals were quartz, plagioclase, with traces of pyrites. The Crushability Work Indices of the rocks were between 30 and 37 KWh/t, which are generally higher than the maximum design value of 31.9 kWh/t, and this situation will pose throughput challenges in that section. The Bond Ball Mill Work Indices of the blends tested were between 16.4 kWh/t and 9.6 kWh/t and a blend ratio of 85% fresh and 15% weathered was found to have a Bond Ball Work Index almost equal to the design value of 14 kWh/t. With gold assays of 2.5 g/t for dolerite, 2.1 g/t for phyllite, 3.7 g/t for sandstone and 3.4 g/t for conglomerate, the gravity recoverable gold was in the order of sandstone 36% > phyllite (31.5%) > dolerite (29.5%) > conglomerate (18%). The overall gold recoveries were in the sequence of conglomerate (95%), sandstone (94%), phyllite (92%) and dolerite (87%). This information could be utilised in developing a proactive plant operations strategies for an operating plant in order to ultimately manage the plant and enhance achievement of set targets. Keywords: Geometallurgy; Ore Blends; Characterisation; Communition Circuit Performance; Gold Recovery

ASME Section XI Appendix L Flaw Tolerance Evaluation of Pressurized Water Reactor Piping Systems to Support Second License Renewal (80-Years Operation)

One of the goals of ASME Section XI is to ensure that systems and components remain in safe operation throughout the service life, which can include plant license extensions and renewals. This goal is maintained through requirements on periodic inspections and operating plant criteria as contained in Section XI IWB-2500 and IWB-3700, respectively. Operating plant fatigue concerns can be caused from operating conditions or specific transients not considered in the original design transients. ASME Section XI IWB-3740, Operating Plant Fatigue Assessments, provides guidance on analytical evaluation procedures that can be used when the calculated fatigue usage exceeds the fatigue usage limit defined in the original Construction Code. One of the options provided in Section XI Appendix L is through the use of a flaw tolerance analysis. The flaw tolerance evaluation involves postulation of a flaw and predicting its future growth, and thereby establishing the period of service for which it would remain acceptable to the structural integrity requirements of Section XI. The flaw tolerance approach has the advantage of not requiring knowledge of the cyclic service history, tracking future cycles, or installing systems to monitor transients and cycles. Furthermore, the flaw tolerance can also justify an inservice inspection period of 10 years, which would match a plant’s typical Section XI in-service inspection interval. The goal of this paper is to demonstrate a flaw tolerance evaluation based on ASME Section XI Appendix L for several auxiliary piping systems for a typical PWR (Pressurized Water Reactor) nuclear power plant. The flaw tolerance evaluation considers the applicable piping geometry, materials, loadings, crack growth mechanism, such as fatigue crack growth, and the inspection detection capabilities. The purpose of the Section XI Appendix L evaluation is to demonstrate that a reactor coolant piping system continues to maintain its structural integrity and ensures safe operation of the plant.