Papers by Keyword: Refinery

Abstract: The rotary experiment apparatus was built to study the erosion-corrosionresistance of carbon steel, 15CrMo steel, duplex stainless steel 2205, nickel based alloy 825 and stainless steel 316L which are commonly used in the sour water environment of refinery. Based on the electrochemical test, the carbon steel and alloys corrosion rates in different ammonium hydrosulfide concentration, fluid velocity and temperature were obtained. The corrosion products film morphology was analyzed by scanning electron microscope (SEM) to find the reasons for corrosion rates difference of carbon steel and alloys. The results showed that the corrosion rates of carbon steel and alloys were increasing with fluid velocity, ammonium hydrosulfide concentration and temperature increase, when the velocity exceeds 6 m/s the corrosion rates essentially unchanged. The maximum corrosion rate of carbon steel at 60 °C and 10 wt% ammonium hydrosulfide concentration was as high as 6.5 mm/year, while the nickel based alloys 825 and stainless steel 316L were less than 1.5 mm/year. The corrosion product films of carbon steel and 15CrMo steel was loose and cracking which can easy to fall off from the substrate when subjected to fluid impact and the corrosive media can easily penetrate into the bottom of corrosion product and continue to corrode substrate. However, the corrosion film of nickel based alloys 825 and stainless steel 316L was dense and tightly bonded to substrate making it has a good corrosion resistance.

Abstract: Refinery units have the feature of operating inertia, long time transition period exists when production modes switch, during which product quality may decline and energy cost raises. The operating inertia have received significant attentions in actual refineries, while few literatures have given enough focus on it which is usually omitted to make scheduling easy. The core of this paper is to deal with the scheduling optimization problem of production modes switch considering operating inertia. By expression of the transition process, a mixed integer linear programming model was built based on a continuous time representation. The model optimizes unit operations by minimizing energy consuming. The formulation approach was used to address the scheduling of a refinery. Case study illustrates the model’s feasibility and efficiency.

Abstract: Stainless steels (SS) possess excellent corrosion, creep and high temperature oxidation resistance and are invariably used in refinery for construction of heater tubes, tube supports, Heat exchanger bundles, piping and internal lining of pressure vessels. Ferritic stainless steel type 405 is used for column strip-lining, martensitic stainless steel type 410 is used for column trays and heater tubes and austenitic stainless steel family is used very extensively for lining, piping, heat exchanger, heater tubes and tube supports. On-stream and turnaround condition monitoring of plant and equipment are carried out for health assessment and mitigation of premature failure. However, catastrophic failures of stainless steel due to stress corrosion cracking, thermal fatigue and stress relaxation cracking are encountered in addition to bulging and cracking of strip-lining. Field repairs of these components are required to be done. Stainless steels are difficult to weld due to low thermal conductivity, higher coefficient of thermal expansion, fissuring and solidification cracking problem during welding. Lower heat input and fast cooling facilitate the welding process. Welding of service exposed stainless steels is more challenging, as it has already undergone metallurgical degradation. Welding of stainless steels is carried out using TIG and SMAW process with matching electrode after establishing the welding specification procedures and welders qualification. Field repairs of stainless steels components are also attempted with original procedures and in case of difficulties, a buttering layer of inconel (ERNiCr3) or ER 309Mo is provided on the welding surface before using matching electrodes. Quality assurance of weld joint is ensured by stage-wise inspection and non-destructive testing. Dye penetrant test of root run and radiographic examination of final weld joint are most common. Post weld heat treatment is done as per code requirement. This Paper highlights three case studies on field repairs of stainless steel components in refinery. 1. Welding procedure followed for repair of bulged and cracked SS 316 strip-lining and cladding on carbon steel backing material. It is a dissimilar welding of SS 316L with degraded carbon steel. 2. Field welding of SS 347 Piping components, which has undergone thermal relaxation cracking at fillet joints. 3. Welding repair of SS 310 cast heater tube support conforming to A 297 Gr HK 40. The Paper also presents brief failure analysis with reasons and remedies.

Abstract: People used to evaluate the energy consumption of the refineries in the quantity respect. There is a need to add quality indicators in the evaluation indicators. The energy consumption indicators about the energy quality are discussed in this paper. And the indicators were used in evaluating the performance of a realistic energy-saving-project. The result shows that choosing appropriate energy with the right quality can save energy resources.

Abstract: Refineries are major CO₂ emitters, so it is imperative for them to conserve energy and reduce CO₂ emissions; biomass is undoutedly of great significance to alleviate the dual pressures resulting from energy crisis and emissions constraints. This paper, by analyzing emission reduction potential of our national petrochemical enterprises and the three main emissions reduction measures-Fuel alternative, carbon utilization and process optimization-taken by refineries in China, proposes that, under the dual pressures from energy crisis and greenhouse effects, importance should be attached to the development and utilization of biomass energy and new refining systems suitable for biomass energy should be built; what’s more, three proposals are suggested for setting up them, including establishing new refining system at remote areas to ensure the adequate supply of raw materials, and creating matched power generation system and new device structure for biomass characteristics. Thereby, a major breakthrough can be made to ease the energy crisis, to truly achieve the aim of energy conservation and “Eat the grass and produce the milk”.

Abstract: In this paper, the hydrogen distribution network of a complex refinery is optimized by the hydrogen surplus pinch method. By plotting the hydrogen purity profiles and hydrogen surplus diagrams, the hydrogen pinch with hydrogen purity of 87% is identified. The corresponding minimum hydrogen utility consumption is 17730.5 Nm3/h. Moreover, the optimal hydrogen distribution network with minimum utility consumption is designed. Compared with the current hydrogen network, the hydrogen utility consumption can be reduced by 10.45%.

Abstract: The main obstacle which prevents the rapid spread of Acoustic Emission (AE) testing on refinery structures in Russia is the complexity of this NDT tool. The lack of well- defined methods of data analysis and the huge amount of AE data collected within each test are the major problems. The possibility of mistakes in a period of testing and data analysis leading to erroneous conclusions related to the condition of the structure sometimes negatively affects the image of the AE method. However, the correct application of AE can bring unique opportunities in the inspection of structures in the industry. Some examples of successful applications and the unique possibilities of AE testing are presented in this paper.

Abstract: Recently, regulatory bodies quite often encourage to adopt risk-based inspection (RBI) and management programs because they can enhance safety simultaneously with deregulation in Korea. RBI is an integrated methodology that factors risk into inspection and maintenance decision making. This paper describes an example of how to use known risk assessment codes (API 580, API 581 BRD) to address such safety analysis requirements for risk management in the refining industry. Specifically, this paper reports the methodology and the results of application to the refinery units using the KGS-RBITM program, developed by the Korea Gas Safety Corporation in reference of API Codes and ASME PC (Post Construction) with a suitable consideration of Korean situation. The results of the risk and reliability assessment using KGS-RBITM program are useful in determining whether the detected defects are tolerable or required to be repaired. The subsequent decisions are to manage the future inspection, repair and maintenance planning in the risk reduction control.