Petroleum Refining Applications

Isomerization


Application

Isomerization in a variety of process configurations alters the arrangement of atoms to convert normal butane into isobutane, and normal pentane and hexane into high octane gasoline components. Isomerization is similar to catalytic reforming in that the hydrocarbon molecules are rearranged, though isomerization only converts normal paraffins to isoparaffins.

Challenges

Near the end of the process, reactor effluent is cooled and separated into the liquid product isomerate and a recycle hydrogen-gas stream. Isomerate is caustic-washed and waterwashed, acid stripped, and stabilized before going to storage. Stabilizer bottoms and wash tanks require level monitoring.

Suitable Products

Aurora® Magnetic Level Indicator

Atlas™ Magnetic Level Indicator

Eclipse® Guided Wave Radar

Catalytic Reformers

Application

Catalytic reforming upgrades low-octane naphthas into high-octane gasoline blending components called reformates. Using heat and pressure with platinum catalysts to rearrange hydrocarbon molecules, this process converts low-octane gasoline fractions into petrochemical feedstocks and higher octane stocks suitable for finished gasoline blending.

Challenges

A hydrogen-rich gas stream is removed from the separator for recycling. Liquid product monitored for level at the bottom of the separator is sent to a stabilizer. Where stabilizer fouling has occurred due to the formation of ammonium chloride and iron salts, a monitored water wash system should also be included.

Suitable Products

Atlas™ Magnetic Level Indicator

Aurora® Magnetic Level Indicator

Eclipse® GuidedWave Radar

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Coking Operations

Application

Coking is the final means of converting the heaviest products of atmospheric and vacuum distillation. Feed is heated and cracked into light gases, gasoline blendstocks, distillates, and gas oil. Level applications for delayed and continuous (contact or fluid) coking include the fractionator, light gas oil stripper, steam, condensate, blowdown and settling drums, and vent gas knockout drums.

Challenges

Process conditions that level instrumentation must contend with include high temperatures, high pressures, foaming, and steam. An interface level gauge in drums that are susceptible to foaming will help avoid foamover and increase coke drum output.

Suitable Products

Eclipse® Guided Wave Radar

Atlas™ Magnetic Level Indicator

Aurora® Magnetic Level Indicator

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Alkylation Tanks

Application

Storage and wash vessels in the alkylation unit include those for fresh and depleted acid and water, an acid analyzer settling pot, and a number of wash tanks. Caustic washes neutralize free acid carried over from the reaction zone and neutralize alkyl sulfates in the net effluent. Water washes decompose remaining esters and remove caustic and salt that might have carried over from the caustic wash.

Challenges

Interface level control in caustic and water washes prevents corrosion and fouling of the deisobutanizer and other downstream units. Levels rising above high set points can cause carryover of caustic or water, while too low levels can cause hydrocarbon carryunder.

Suitable Products

Aurora® Magnetic Level Indicator

Atlas™ Magnetic Level Indicator

Eclipse® Guided Wave Radar

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Acid Settling Tanks

Application

Alkylation is a combining process that creates alkylate, a premium, high-octane blending stock. A large acid settler tank within the unit allows for separation of the acid/hydrocarbon emulsion created in the reactor. Sight glasses have traditionally measured settler level, but these are susceptible to plugging and require diligent flushing at regular intervals.

Challenges

Interface level control of the settler is required. Product acid cross-contamination causes overall efficiency problems and can result in hazardous conditions. Inaccurate settler level indication is a frequent cause of physical acid carryover in the reactor effluent. Release of acid can cause extreme hazards to both process and personnel.

Suitable Products

Eclipse® Guided Wave Radar

Atlas™ Magnetic Level Indicator

Aurora® Magnetic Level Indicator

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Finished Product Storage

Application

Finished refinery products stored in tanks with capacities that often exceed 100,000gallons are motor gasoline, jet fuel,diesel fuel, fuel oils, and LPG. Marketed products also include feedstocks for textiles, tires, pharmaceuticals and plastics.

Challenges

Tank monitoring uses buoyancy, pressure, servo-driven, and radar. Tanks may be provided with automatic overflow control and alarm systems. Automated tank gauging networks with proprietary protocols are a vital part of tank farm architecture. Today, thousands of tanks can be linked in a network offering enhanced data acquisition, field calibration and remote diagnostics.

Suitable Products

Aurora® Magnetic Level Indicator

Atlas™ Magnetic Level Indicator

Eclipse® Guided Wave Radar

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Blending Operations

Application

Mixing finished gasoline requires level monitoring of blending stocks, in-line blending, additive storage, dilution systems and injection systems. Blend stocks are straight-run gasoline, alkylate, reformate, benzene, toluene and xylene. Additives include octane boosters, metal deactivators, anti-oxidant and knock agents, gum and rust inhibitors, and detergents.

Challenges

Level is normally measured only for inventory control and, in some cases, custody transfer. The precision of level indication that is required varies. If level is used only for internal inventory control, a less accurate measurement can be used. If level is used for custody transfer, highly accurate measurements are required.

Suitable Products

Eclipse® Guided Wave Radar

Atlas™ Magnetic Level Indicator

Aurora® Magnetic Level Indicator

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Column Reboilers

Application

A heat exchanger positioned near the bottom of the distillation column re-heats and vaporizes liquid and reintroduces the vapor several trays higher. This improves separation by introducing more heat into the column. For effective functioning of the reboiling process, level monitoring of the reboiler is required.

Challenges

In some steam reboilers, the level must be controlled so that only a percentage of tubes are covered. This allows a control scheme to regulate the heat transfer in the reboiler by controlling the percentage of the reboiler tubes covered by liquid. This is a critical control loop as heat transfer into the liquid is a strong function of the percentage of tubes covered.

Suitable Products

Aurora® Magnetic Level Indicator

Atlas™ Magnetic Level Indicator

Eclipse® Guided Wave Radar

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Solvent Extraction

Application

The heavy fraction remaining following the distillation of crudes is called petroleum resids. A variety of solvent-extraction processes yield deasphalted oil (DAO) from these resids. These oils serve as downstream feedstocks for catalytic crackers and hydrocrackers. Depending upon the system configuration, level monitoring of the separator, preflash, stripper and hot oil phases may include surge and flash drums, separators and strippers.

Challenges

Level control is critical because interface level control of the separator feeds the flash drum, whose level feeds the stripper, etc. Application extremes include high temperatures, high pressures, and the presence of steam.

Suitable Products

Eclipse® Guided Wave Radar

Atlas™ Magnetic Level Indicator

Aurora® Magnetic Level Indicator

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Reflux Accumulators

Application

A heat exchanger removes vapor from the upper parts of the fractionator, cools it to a liquid, and pumps it into an accumulator (reflux drum). Reflux pumps then draw liquid from the bottom of the accumulator and pump part of it back (reflux) where it is reintroduced at a lower point in the column. This refluxing process improves separation in the column by assuring sufficient downward liquid flow meeting the rising vapor.

Challenges

Accurate and reliable level monitoring and control is necessary for the reflux accumulator to serve as a distribution point for reflux and distillate, and prevent excessive reflux from returning back to the tower.

Suitable Products

Eclipse® Guided Wave Radar

Atlas™ Magnetic Level Indicator

Aurora® Magnetic Level Indicator

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Distillation Columns

Application

Following desalination, crude oil enters the distillation column where fractional distillation separates hydrocarbons into separate streams, cuts or fractions. For optimum operation of the distillation column, level controls must contend with occurrences of foaming, bubbling and moderate-to-high temperatures.

Challenges

Sight glasses and displacer systems mounted in external chambers have traditionally provided distillation level measurement. Today, radar retrofitted in these existing chambers is gaining popularity due to radar's less demanding maintenance schedule and ease of retrofit. High product temperatures necessitate temperature-tolerant level sensors.

Suitable Products

Aurora® Magnetic Level Indicator

Atlas™ Magnetic Level Indicator

Eclipse® Guided Wave Radar

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Preflash Drums

Application

Located in the preheat train of the distillation column, a preflash drum system separates the vapors generated by preheating before entering the heater or main column. This prevents higher heater firing or pressure drops and reduces vapor loading of the column to avoid flooding.

Challenges

Preflash drums create moderate foam that can affect measurement accuracy of liquid levels and decrease distillate production in the atmospheric column. Too low of a preflash drum level will cause pump cavitation of the flashed crude. Too high of a level will cause liquid carryover to the distillation column.

Suitable Products

Eclipse® Guided Wave Radar

Atlas™ Magnetic Level Indicator

Aurora® Magnetic Level Indicator

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Crude Desalting

Application

Salt in the crude stream presents serious corrosion and scaling problems and must be removed. Salt is dissolved within the remnant brine of the crude oil. Desalting removes both salt and the residual free water. Though the refinery is the most economical place for desalting, pipeline requirements often necessitate field desalting.

Challenges

Level instrumentation is integral to single and two-stage desalting systems, multiple orifice plate mixers, and the settler tank of a chemical desalter. Interface level control keeps free water from hitting the desalter electrodes and prevents expensive damage. The Interface level should be kept constant otherwise electrical field changes will disturb electrical coalescence.

Suitable Products

Eclipse® Guided Wave Radar

Atlas™ Magnetic Level Indicator

Aurora® Magnetic Level Indicator

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Crude Dewatering

Application

All unrefined crude oil stored in tanks has a percentage of water entrained within it, and while stored in tanks, separation naturally occurs with water collecting at the bottom of the tank beneath the oil. The two fluids are very distinct except for a "black water" or "rag" interface layer which is an emulsion of mixed oil and water. To dewater the tank, water is drawn off of the bottom of the tank and is then sent off to water treatment.

Challenges

Level controls designed for interface detection will sense the beginning of the oil/water interface during dewatering procedures and provide feedback to a control system which will terminate water draw-off when appropriate.

Suitable Products
Eclipse® Guided Wave Radar
 

Crude Storage

Application

Upon arrival at the refinery terminal, crude oil is pumped into above-ground storage tanks with capacities of thousands to millions of gallons. Raw crude is stored in floating-or fixed-roof tanks field-built to API standards. Tank level measurement by non-contact radar has gained share over mechanical float type and servo gauges due to its accuracy, low maintenance, no moving parts and fast set-up.

Challenges

Upon arrival at the refinery terminal, crude oil is pumped into above-ground storage tanks with capacities of thousands to millions of gallons. Raw crude is stored in floating-or fixed-roof tanks field-built to API standards. Tank level measurement by non-contact radar has gained share over mechanical float type and servo gauges due to its accuracy, low maintenance, no moving parts and fast set-up.

Suitable Products

Eclipse® Guided Wave Radar

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Hydrocracking

Application

Heavier feedstock difficult to process by cat cracking or reforming can be converted by hydrocracking. By combining catalytic cracking and hydrogenation to crack feedstock in the presence of hydrogen, hydrocracking produces gasoline and distillate blending streams. About a dozen different hydrocracking process schemes are in current use.

Challenges

Level controls for the catalyst stripper, separator liquid and flash drum liquid must contend with severe process conditions to maintain optimum operation of the hydrocracker. These conditions include elevated temperatures and pressures, the presence of steam and high pressure hydrogen, and aggressive corrosives.

Suitable Products

Aurora® Magnetic Level Indicator

Atlas™ Magnetic Level Indicator

Eclipse® Guided Wave Radar

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Catalytic Strippers

Application

Variations in cat cracking include Selective Component Cracking (SCC) for polypropylene production, a two-vessel and external-reactor design for processing heavy residue feeds, and a UOP process for converting gas oils and resid feedstocks. All crackers employ a steam stripper to remove hydrocarbons entrained in the spent catalyst.

Challenges

Stripper level control allows sufficient residence time for stripping steam to displace hydrocarbons for recovery. It also maintains sufficient pressure to keep air in the regenerator from reverse flow into the reaction system, thereby causing a hazard. A waste heat recovery steam drum would also require monitoring.

Suitable Products

Eclipse® Guided Wave Radar

Atlas™ Magnetic Level Indicator

Aurora® Magnetic Level Indicator

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Chemical Storage and Feed

Application

From acids to water treatment additives, a wide array of chemicals are stored at a refinery in vessels that range in size from plastic totes to large steel tanks. Chemicals such as sulfuric and hydrochloric acid, sodium hydroxide, liquid catalysts, blending additives and water treatment chemicals are essential to a refinery's day-to-day operation.

Challenges

Liquid solution storage and day tanks require stringent level monitoring to ensure ongoing chemical processing. The nature of the chemical, the geometry of the holding vessel, and the presence of mixers or other hardware will determine the most suitable level technology for the storage or feed application.

Suitable Products

Aurora® Magnetic Level Indicator

Atlas™ Magnetic Level Indicator

Eclipse® Guided Wave Radar

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Hydrodesulfurization

Application

Catalytic Hydrotreating treats hydrocarbon liquids in the presence of hydrogen. This process removes 90 percent of the sulfur, nitrogen, oxygen, and metals from feedstocks. Hydrotreating can also provide hydrodearomatization (HDAr), heavy diesel hydrocracking (HDHDC), dewaxing, and performance enhancements of pyrolysis gasoline and diesel.

Challenges

Hydrotreatment will necessitate level indication of liquid/gas separators and water wash tanks. Level devices suited for high temperatures and pressures are essential in removing contaminants that can have detrimental effects on equipment, catalysts, and the quality of the finished product.

Suitable Products

Atlas™ Magnetic Level Indicator

Aurora® Magnetic Level Indicator

Eclipse® Guided Wave Radar

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