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Steam generation for the purposes of thermal recovery includes facilities to treat the water (produced water or fresh water), generate the steam, and transport it to the injection wells. A steamflood uses high-quality steam injected into an oil reservoir. The quality of steam is defined as the weight percent of steam in the vapor phase to the total weight of steam. The higher the steam quality, the more heat is carried by this steam. High-quality steam provides heat to reduce oil viscosity, which mobilizes and sweeps the crude to the producing wells.
Abstract Objective/Scope 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. Methods, Procedures, Process 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. Results, Observations &Conclusions 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. Novel/Additive Information 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.
Abstract This paper will address the major considerations for the design of hydrogen plants based on the steam reforming process, which is the most commonly applied technology for hydrogen generation. In refineries hydrogen is an essential utility to prepare clean transportation fuels. It is not only used for hydro treatment of finished products, but also for deeper hydro conversion of heavier and sourer crude fractions, for instance in hydrocrackers. In most refineries a hydrogen plant is present that feds into a network that serves the various consumers. Often recovered hydrogen from off gas streams from hydro processing units or catalytic reformers is (re-)injected in the network. Steam reforming is an endothermic process where hydrogen is generated by reaction of steam with hydrocarbons over a Ni-based catalyst. Usually the reactor is a direct fired multi-tube reactor, operating at temperatures around 850 - 920 C, and pressures around 25-35 barg. Due to the high reaction temperatures, the heat recovery from flue gases and process gas is an essential part of the design of the hydrogen plant, and determines largely the overall efficiency of the plant. Following topics are addressed: –Plant flowsheet –Process design optimization –Feedstock flexibility –Hydrogen generation vs. hydrogen recovery –Furnace mechanical design (furnace types, design aspects of radiant and convection section, internals, supporting, piping manifolds, ducting, etc) –Furnace operations and safeguarding –Managing NOx emissions Hydrogen production is an essential part of nowadays refinery set-ups. The design of the hydrogen plant shall be carefully optimized between technology licensor and end-user, as it is a large energy consumer, represents substantial investment cost and is deeply integrated into the refinery.
The costs of steam generators vary appreciably with the type of fuel. A costcomparison between oil-fired equipment and a gas-fired unit indicates that theoil-fired equipment, when installed, can cost as much as 25 percent more than acomparable gas-fired unit. The cost analysis also shows why the operating andmaintenance costs may run 22 per cent higher. Essential operating andmaintenance techniques are discussed to emphasize the necessity of maintaininghigh thermal efficiency, which tends to reduce the over-all operating andmaintenance costs.
FUEL FOR THE STEAM GENERATOR represents one of the most significantoperating costs in stimulating the production of heavy oil; however, there area number of related costs associated with the firing of particular fuels thatare often inadvertently overlooked in the initial economic or feasibilitystudies. It is the purpose of this paper to point out some of these costs,which in turn may reflect a more realistic operating cost estimate of the steamgenerators. To illustrate where and how some of these costs occur, a comparisonhas been made between a gasfired generator and one that is fired with leasecrude. Included in this comparison is a description of the equipment andits function, along with the operating and maintenance techniques that aregenerally practiced to achieve the maximum level of performance.
The once through generator (see Figure 1) was specifically)7 developed forthermal recovery applications and provides features not available inconventional ste:3tm boilers. Among the important advantages are thefollowing:
STEAM GENERATOR DESIGN
The basic design of this type of generator does not change appreciablywhether it is gas-fired or oil-fired, except where additional components (seeFigure 1) are necessary and essential in the firing of crude oil. Theseadditional facilities include a pilot gas system (usually LPG), atomizing aircompressor system, atomizing steam system, electric and hot-water-to-oil heatexchangers, electric and pneumatic controls, soot blowers, -t pump and heatset, an adequate fuel storage tank and all the necessary piping and materialsto hook up these facilities. Perhaps one distinct design difference would bethe "L"-type convection section, as shown in Figure 2. This design featureshorizontal tubes with longitudinal welded fins and is mounted in a position forparallel flow of flue gases rather than the cross-flow design of theconventional economizer sections. This "L"-type convection section wasprimarily developed for oilfired generators, burning poorer grades of crude oilor pitch, as this design is less susceptible to fouling.
ABSTRACT Successes with steam injection as a means of increasing recovery from certain types of oil reservoirs have brought an entirely new line of equipment to the oil fields. This paper discusses operating principles and characteristics of equipment needed to carry out an oilfield steaming program, except for the steam generator. Water-treating and handling equipment, flow lines, well heads, down-hole tools, and accessory items are covered. INTRODUCTION Whether oil production is stimulated through the steam-soak (huff-and-puff) method or by well-to-well steam drive, there is more to the operation than just putting steam into the ground. Careful engineering of all phases of the operation is needed to avoid physical damage to surface equipment and injection wells, and chemical and mechanical damage to the reservoir Proper selection and application of equipment is one of the first steps in this careful engineering design, which covers the full range of operations from water treatment on the surface to injection of steam into the reservoir many feet underground. WATER TREATMENT Two major differences between industrials team boilers and oil-field steam generators dictate the differences in feed-water treatment, Fig 1. Conventional industrial steam systems usually operate oil a closed cycle in which steam used for turbine operation, heating of buildings, etc is returned to the holler for conversion to steam again Oil-field steamers operate on a "once-through" basis, where all steam generated is injected into the reservoir, and never recycled. Only a small amount of makeup water is needed to replace that which is accidentally lost from a conventional boiler system, or that which is used to "blow down" the boiler but feed water for an oil-field steam generator must be continuously replaced on a 100-percent basis. Cost of water treatment for a conventional boiler system, on a unit basis, is not too important because of the small number of 'units involved, but this same cost might be prohibitive in the oil fields. Conventional steam boilers take the steam to the dry saturated condition, or into the super-heat region, whereas oil-field steam is "wet" - generally about 80-percent quality (80-percent in the vapor phase, 20-percent in the liquid phase). The first of these differences is a disadvantage; the second is a distinct advantage The water-handling portion of a steam-injection system involves filtration, chemical treatment, storage, deaeration, conversion to steam, separation (optional), and metering (Fig 2) A description of equipment needed to treat feed water for oil-field steamers is impossible without some discussion of water-conditioning fundamentals, but no attempt will be made to cover the subject in detail as this has been clone adequately in recent publications Filters Feed water should be free of excessive suspended matter (non-ionic solids) to prevent contamination of subsequent treating equipment and plugging of parts of the system, including the sand face of the injection well Fig. 1 - Oil-field Steam-generating ProceduresRequire Unique Water-treatment (Available in full paper) Fig. 2 - Basic Components of a Steam-injection System, to the Well Head(Available in full paper)