DIFFERENT TERMS & ABBREVIATIONS USED IN OIL & GAS INDUSTRY (REFINERIES) & IN PETROCHEMICAL INDUSTRY INCLUDING MOST COMMONLY USED CHEMICAL INDUSTRY TERMS.
P
PACKED TOWER
A fractionating or absorber tower which is filled with small objects (packing) to effect an intimate contact between rising vapour and falling liquid.
PACKING
1. Typically PALL or RASCHIG rings of stainless steel or ceramic as used in a packed tower. May be DUMPED or STRUCTURED ‑ The latter being assembled rather than tipped in which results in lower p.d. and increased vapour/liquid contact thus greater efficiency.
2. Any material used to pack, as a layer of material put between the surfaces of a flange or used in a stuffing box to prevent leakage.
PALL RINGS
Usually of stainless steel, similar to Rashing rings, but with internal vanes (to increase surface area).
PARAFFIN‑BASE CRUDE
Crude oils which contain paraffin wax but little or no asphaltic matter.
PARAFFINS
Straight(N) or branched (ISO) open chain saturated hydrocarbons.
PARAFFIN WAX
Wax of solid consistency having a relatively pronounced crystalline structure, extracted from certain distillates of petroleum, shale oil etc. Refined paraffin wax has a very low oil content; it is white with some degree of translucency, almost tasteless and odourless and slightly greasy to the touch.
PARTIAL CONDENSER
A heat exchanger, which condenses part of a vapour stream. For example, partial condensers are used to condense the reflux liquid stream and liquid top product from the overhead vapours of a fractionation column.
PARTIAL PRESSURE
Partial pressure of a component of a mixture in vapour‑liquid equilibrium is that part of the pressure which is contributed by that component.
PENETRATION
Consistency, expressed as the distance that a standard needle or cone penetrates vertically into a sample of the material under known conditions of loading, time and temperature. A measure of the hardness and consistency of asphaltic bitumen by which a weighted special cone or needle will penetrate the sample in five seconds, the temperature, unless otherwise stated, being 25C (77F).
PERMIT TO WORK
A permit raised for any job that is carried out in the “restricted area”
PETROIL MIXTURE (2 STROKE MIX)
A lubricating system for small two‑stroke gasoline engines, in which the lubricant is mixed in suitable proportions with a gasoline to make a petrol oil mixture. During its passage through the engine some of the heavier and un-evaporated petrol oil fractions are deposited on bearing surfaces and so provide lubrication.
PETROL
Term commonly used for motor spirit or gasoline.
PETROLEUM
A material occurring naturally in the earth, predominantly composed of mixtures of chemical compounds of carbon and hydrogen with or without other nonmetallic elements such as sulphur, oxygen, nitrogen, etc. Petroleum may contain, or be composed of, such compounds in the gaseous, liquid, and/or solid state, depending on the nature of these compounds and the existing conditions of temperature and pressure.
PETROLEUM NAPHTHA
A generic term applied to refined, partly refined, or unrefined petroleum products and liquid products of natural gas, not less than 10 percent of which distill below 347F (175C), and not less than 95 percent of which distill below 464F (249C) when subjected to distillation in accordance with ASTM method D86.
PETROLEUM SPIRITS
Refined petroleum distillates with volatility, flash point, and other properties making them suitable as thinners and solvents in paints, varnishes, and similar products.
PETROLEUM WAX
See crude wax.
PHENOL
Hydroxyl derivative of aromatic hydrocarbons. Found in effluent water ‑ occurs from contact with certain crude’s.
PHOSPHATE
1. A salt of phosphoric acid.
2. At NZRC ‑ generally used to refer to TRISODIUM PHOSPHATE, an alkaline water treatment chemical. Na3Po4
pH VALUE
The logarithm of the reciprocal of the hydrogen ion concentration. This indicates the acid or alkaline condition of a substance, pure water and neutral solutions having a pH of 7. Acid solutions have a pH less than 7; alkaline solutions, a pH greater than 7.
PIG
Device sent down pipelines for various purposes. Types include Polypigs, swabs, brush pigs, go‑devils and linelogs.
PILOT PLANT
A small version of the full‑scale plant in which a laboratory pursues development work, after bench‑scale investigation of a new process has shown promise.
PIPELINE
A line of pipe with pumping machinery and apparatus for conveying a liquid or gas.
PISTON
In engines and pumps, a reciprocating device in a cylinder or tube which receives pressure from, or delivers pressure to, a fluid.
PISTON RING
A ring used to maintain a gas tight seal between the piston and the cylinder and to control cylinder wall lubrication.
PITTING
Irregular corrosion in metalwork.
PLASTICIZERS
Non‑volatile liquids or low‑melting solids which, when added to another material change certain physical and chemical properties of that material, mainly imparting greater toughness, improved stability and increased flexibility.
PLATFORMING
A reforming process which makes use of a catalyst containing platinum and excess of hydrogen. Catalytic reforming of straight‑run heavy gasoline (Naphtha) produces a product which is richer in aromatics and branched‑chain paraffins and poorer in naphthenes and straight chain paraffins. The hydrogen produced in this process is used for hydrodesulphurisation and hydrocracking.
POLYELECTROLYTE
Substance used to encourage flocculation in water treatment units.
POLYMER
A substance produced from another by polymerisation, i.e. the combination of a number of identical molecules to form a larger one.
POUR POINT
The lowest temperature at which an oil will flow in a laboratory test, measured under specified conditions.
POWER RECOVERY TURBINE
Equipment designed to utilise the energy given up where a process drops from a high to a lower pressure.
PREDILUTON (RATIO)
Butane added to short residue to aid dispersal before entering the extractor in the B.D.U.
Ratio of predilution butane to short residue.
PREHEAT
To heat, previous to some treatment; as an oil to be subsequently distilled, or as a body of gas or oil to be used as fuel.
PREHEATER
Any form of apparatus in which heat is applied to a material prior to its introduction into the main heating apparatus. The application of heat is usually accomplished by means of hot streams which have to be cooled and whose heat would otherwise be wasted. (See also HEAT EXCHANGER).
PRESSURE
The force or thrust exerted on a surface, normally expressed as force per unit area. Pressure is exerted in all directions in a system. Common examples; air pressure in a tyre, or water pressure at some depth in the ocean.
PRESSURE DROP
The decrease in pressure due to friction, which occurs when a liquid or gas passes through a pipe, vessel, or other piece of equipment.
PRESULPHIDE
To add sulphur (as DMDS or CS2) in order to initially activate a catalyst by changing the oxide sites to sulphides.
PRIMARY
A term used to describe the structure of certain classes of organic compounds, such as alcohol’s and amines. For example, a primary compound is one in which one hydrogen atom in the carbinol or amino groups is replaced by a univalent hydrocarbon radical.
PRIMARY AIR
The air required for combustion in a furnace which is mixed with the fuel (gas, oil, pulverised coal, etc.) in and through the burner (c.f. Secondary Air).
PRIMARY PROCESS
A process based on physical separation, e.g. Fractionation, gravity separation.
PRIME MOVER
Any machine capable of producing power to do work.
PROCESS INTEGRATION
A term denoting the selection and arrangement of refinery processes and the optimum use of the heat contents of the various plant streams.
PROMOTER
A substance which may considerably increase the activity of a catalyst. For example the catalytic action of iron is greatly increased when the catalyst contains a small amount of oxides of aluminium or silicon etc., e.g. C1‑ on Platformer and F‑ on hydrocracking catalysts.
PROPANE C3H8
A hydrocarbon of the paraffin series used for heating, welding and metal cutting. At ambient temperature it can be stored under pressure as a liquid.
PROPYLENE C3H6
A hydrocarbon of the olefin series. Important base material for the chemical industry. Propylene is used to make iso‑propanol, polypropylenes, plasticisers and glycol’s.
PROSS
Shell computer system for process control and optimisation. This has passed into history in 1999
PUKING
The foaming and rising of oil to the extent that part of the liquid is driven out of the vessel through the vapour line. (See also SURGE).
PURGING
The removal of one fluid from a vessel or plant by introduction and subsequent evacuation of a second fluid. A common usage of this operation is in the removal of hydrocarbon vapours or air from a plant by flushing with nitrogen.
PYROPHORIC
Takes fire spontaneously upon contact with air. Certain forms of iron sulphide exhibit this tendency. (Pyrophoric iron).
Q
QUENCH
To suddenly cool hot material discharging e.g. into a vacuum column, by injecting cool oil into the base; its purpose is to check the cracking reaction quickly to avoid coking.
QUENCH GAS
Cool gas injected between the hydrocracker reactor beds used to control reaction temperature.
QUENCHING OILS
Specially refined high‑flash mineral oils used for hardening alloy steels.
RADIANT ENERGY
Energy sent out or emitted by rays or waves.
R
RADIANT SECTION
Section of a furnace exposed to the actual combustion of the fuel.
RADIATION
The act of emitting energy, particularly rays of light or heat.
RADICAL
In chemistry, a group of atoms whose affinity for one another is so strong that, in chemical reactions, the group acts as a single atom, and is replaced or introduced into a new compound without rearrangement of the atoms bound together in the radical. It can never exist alone as a separate compound.
RAFFINATE
The product resulting from a solvent extraction process and consisting mainly of those components that are least soluble in the solvent.
RASCHIG RING
Tower packing consisting of a small, hollow cylinder with length equal to its diameter; may be made of metal, ceramic, plastic or other material.
REACTION
Any chemical change; the transformation of one or more molecules into other molecules.
REACTION TIME
The interval during which the material being processed experiences chemical change.
REACTOR
Term applied to the part of a plant where a chemical reaction takes place.
REBOILER
A special type of heat exchanger for the supply of heat to the bottom of fractionating columns.
RECIPROCATING COMPRESSOR
A displacement compressor relying on forward and backward piston movement.
RECIPROCATING PUMP
A positive displacement pump consisting of a plunger or a piston moving back and forth within a cylinder(s). With each stroke of the plunger or piston, a definite volume of liquid is drawn in through the suction valve(s) and subsequently pushed out through the discharge valves(s).
RECLAIMER
Part of the reformer process used to reclaim valuable Sulfinol solution that would otherwise be lost as condensate. Also removes impurities (notably DIPA Oxazolidone) from reclaimed Sulfinol.
RECONTACTING
Process of splitting a stream into separate gas/liquid stream and then recontacting them under pressure. This improves the quality of both streams (i.e. makes the gas lighter and the liquid denser). Mainly used for maximising C5 (Pentane) retention as a Mogas blending component.
RECYCLE GAS
Gas fed back from a later stage of process (usually from the separators) to the early stage. Usually impure and heavy.
RECYCLE OIL
Oil recycled from a later stage of the process to an earlier one. HCU second stage feed is recycled from the HCU fractionator and consists of insufficiently cracked material (i.e. heavier than gas oil).
RECYCLE RATIO
The quantity of recycle stock relative to the quantity of fresh feed. The units of quantity in this relationship vary with the plant concerned. See also combined feed ratio.
RECYCLING
a) The maintenance of reservoir pressure through re‑injection into the reservoir of the produced gas, after extraction of the condensate in a gas plant.
b) Continuously feeding back part of a substance obtained or used in a process for further processing or use.
REDUCED CRUDE
A residual product remaining after the removal, by distillation or other means, of an appreciable quantity of the more volatile components of crude oil.
REDUCTION
The removal of oxygen ‑ or addition of Hydrogen to a compound. Effectively the opposite of oxidation.
REFINERS MARGIN ‑ GROSS
The difference in value between the product value ex refinery and landed value of feedstock and blendstock.
REFINERS MARGIN ‑ NET
The gross refiners margin less fixed and variable cost of refining.
REFINERY
A plant, with all its included equipment, for manufacturing finished or semi‑finished products from crude oil.
REFINERY FUEL AND LOSS
The difference in intake and output due to the amount used as fuel and lost through tank breathing etc.
REFINING
The separation of crude oil into its component parts, and the manufacture therefrom of products needed for the market. Important processes in refining are distillation, cracking, chemical treating, and solvent extraction.
REFLUX
A part (if the top product is in the liquid state) or all (if the top product is the vapour phase) of the condensed top vapour of a fractionating column, which is returned to the top of the column. The purpose is to create an extra downward flow of liquid; if properly applied this liquid acts as an absorbing agent for the relatively heavy components which are thus rejected from the top product.
REFLUX CONDENSER
A condenser which constantly condenses vapours and returns liquid to the original distilling unit or to lower levels of a fractionating tower.
REFLUX RATIO
1. The quantity of reflux per unit quantity of distillate removed from the process as a product (forward flow).
2. For design purposes, the ratio of liquid reflux to vapour at any given point in a fractionating column. Values may range from zero to unity.
REFORMING
1. See catalytic reforming, Platforming.
2. Process for the manufacture of hydrogen from steam and light hydrocarbons.
REFRACTORY
1. Any material not easily affected by heat, such as firebrick.
2. Difficult to decompose, for example, in cracking gas oil to produce gasoline.
REFRACTORY BRICK
A brick which is used as a lining for the interior of fireboxes in furnaces and boilers. Refractory brick is constructed so that it can withstand very high temperatures, but it is not a very good insulator.
REGENERATION
1. The process of restoring a material to its original strength or properties.
2. In a catalytic process, the reactivation of the catalyst, usually done by burning off the coke deposits under carefully controlled conditions of temperature and oxygen content of the regeneration gas stream. May be done in situ or ex situ.
REGENERATOR
Term applied to the part of a catalytic cracking unit or continuously regenerable platformer (CCR) where the spent catalyst is regenerated by burning off the coke.
REID VAPOUR PRESSURE (RVP)
The pressure caused by the vapourised part of a liquid and the enclosed air and water vapour, as measured under standardised conditions in standardised apparatus: the result is given in Kilo pascals at 37.8oC, although normally reported simply as "RVP in kPa". There is no simple relation between the RVP and the true vapour pressure of the liquid. RVP gives some indication of the volatility of a liquid, e.g. gasoline. Lower in summer & higher in winter.
RELIEF VALVE
A spring loaded valve fitted on any piece of equipment or plant where normal operating pressures are above atmospheric. This type of valve automatically opens, thus relieving internal pressure when the latter exceeds the maximum permissible level.
RERUNNING
The distillation of an oil which has already been distilled. Necessary when a finished batch has been put off grade for any reason.
RESEARCH OCTANE NUMBER (RON)
The octane number of a motor gasoline determined in a special laboratory test engine, under mild engine severity conditions, giving a rough measure of the low speed knock properties of the gasoline.
RESIDENCE TIME
The average length of time a quantity of reactant spends in contact with catalyst, or within a particular part of the process.
RESIDUAL FUEL OIL
Fuel oil consisting mainly of long, short or cracked residue (in contrast to distillate fuel oil).
RESIDUE
The heavy residual liquid from the atmospheric distillation of crude oil is called long residue. If such residue if further distilled under vacuum a still heavier residual liquid results, which is called short residue.
RESIN
Organic compounds produced by polymerisation.
1. Water treatment resins are used for water softening. With a very large surface area, liken to a sponge.
2. Epoxy and polyester resins of various types are used as fillers, adhesives and coatings.
RETAINED EARNINGS
Accumulated profits not distributed to shareholders.
RETURN BEND
A U shaped pipe fitting, used to connect parallel pipes so that fluid flowing into one will return in the opposite direction through the other.
RICH ADIP
Adip containing dissolved H2S.
RING COMPOUNDS
Organic compounds in which the atoms of a molecule are arranged so as to form at least one closed ring, for example, naphthenes and aromatics. Also called cyclic compounds.
RISER
1. That portion of the bubble plate assembly which channels the vapour and causes it to flow upward to escape through the liquid.
2. Fixed vertical line used to get fire water to high levels.
ROCKET FUEL
Propellant consisting of two components, oxidiser and fuel, which react to give gaeous products and release energy. Rocket fuels are compared on the basis of specific impulse, which means the pounds of thrust produced per pound of fuel burned per second. Rocket fuels may be liquids or solids. In the latter case, the two components must be intimately premixed. In some instances the liquid system may be a single liquid, in which case it is called a mono‑propellant.
ROTAMETER
Simple flow gauge utilising a ball or float in a tapered graduated tube. The greater the flow, the more it raises the ball up the tube.
ROTARY PUMP
A positive displacement pump used mainly to pump liquids which are either too viscous or too difficult to obtain suction with a centrifugal pump. There are many types of rotary pump designs. One of the most common is the gear type, in which two gears mesh and rotate toward each other within a very close‑fitting casing. The liquid is trapped between the gear teeth and the casing and is carried around to the discharge side of the pump. The meshing gear teeth prevent the liquid from returning to the suction side.
RUNDOWN TANK
One of the tanks in which are received the condensates from the stills, agitators, or other refinery equipment, and from which the distillates are pumped to larger tanks known as work tanks or storage tanks. Rundown tanks are also known as "pans" or receiving tanks. If the condensates were received directly into the large storage tanks, possible puking of a still could unnecessarily contaminate a large quantity of distillate.
S
SAE CLASSIFICATION
The SAE devised a system for the classification of motor oils and transmission oils. It is based on the viscosity at 0 or 100oC. Motor oils are on the scale 5W ‑ 50 and transmission oils are 80‑250.
SAFEGUARDING
Total procedure for safety proofing plant. Includes relief systems, functional logic and emergency procedures.
SALT
A compound in which a metal or other positive ion exists in place of the hydrogen of an acid (e.g. sodium chloride, in which sodium replaces the hydrogen of hydrochloric acid), formed:‑
1. By direct replacement of the acid hydrogen with a metal;
2. By neutralisation of the acid with an appropriate alkali; or
3. By double decomposition.
SAMPLE
Sample of a process flow, tank etc. taken for laboratory analysis.
SATURATED HYDROCARBON
A hydrocarbon of such molecular structure that all adjacent carbon atoms are connected by not more than one valence or bond; or, diagrammatically as follows: C‑C. Each valence not taken up by adjacent carbon atoms connects with a hydrogen atom.
SATURATION TEMPERATURE
Of steam ‑ the temperature at a given pressure, at which steam exists in conjunction with water e.g. 100oC at atmospheric pressure.
SCAVENGERS
Chemical additives which remove or inactivate impurities or undesired materials in a mixture or process, e.g. hydrazine is an oxygen scavenger used in water treatment.
SCHEDULING
The day to day planning of refinery operations to meet long term programmes.
SCHOEPENTOETER
Dutch for vane trumpet ‑ an internal distribution device, may be sideways or downwards pointing.
SEAL
A device used to seal the contents of a pump/compressor from the atmosphere. Occasionally more explosive and complex then the pump itself.
SECONDARY AIR
The air which provides the oxygen necessary for the complete combustion of fuel (gas, oil, powdered coal, etc.) and which was not provided by the burner in the form of primary air.
SECONDARY PROCESS
A process based on a chemical change, e.g. Hydrocracking, Platforming, usually catalysed.
SEIZE
To stick or fail to function, as in engine bearings, because of expansion, caused by heat, friction, or scoring. Also called "freeze".
SENSIBLE HEAT
The heat added to, or taken from, a body when its temperature is changed. Note that no change in stage of the body (e.g. solid to liquid) is involved, c.f. latent Heat.
SEPARATOR
1. An apparatus in which heavy liquid impurities are separated from oil.
2. The part of a distilling apparatus in which a partial separation of the vapours is effected by means of contact with cooling surfaces.
SEPARATION INDEX
A measure of the degree of separation between components in a distillation column
SEPARATION PROCESSES
Manufacturing processes based on differences in the physical properties of the components of a mixture. See Fractionation, Primary Process.
SETTLER
A separator, a tub, pan, vat, or tank in which the partial separation of a mixture is made due to difference in density. The operation may be continuous or batch. The separation may be solids from liquid or gas; liquid from gas.
SETTLING POINT
Laboratory test determining the temperature at which solidification of a molten wax begins.
SETTLING TANK
A tank employed for separating two liquids which are not miscible. If the liquids do not form an emulsion they separate into layers according to their specific gravities, and these layers can be drawn off from different levels in the tank.
SHAREHOLDERS INVESTMENT
Retained Earnings plus Capital Reserves plus Original Equity = total investment made in the Company by Shareholders.
SHIFT REACTION
Conversion of CO to CO2 by addition of water, following general reaction CO + H2O ‑‑> CO2 + H2. Both Hi and low temperature shift reactions are used.
SHORT RESIDUE
The residue resulting from vacuum distillation of long residue. (Removal of vacuum gas oil and waxy distillate).
SIDE STRIPPER
A fractionating column for stripping undesired volatile components from a side stream which is drawn off as a liquid from a main fractionating column. Various fractions may be drawn off from one main column, and be stripped in as many side strippers.
SIDESTREAM
A liquid stream taken from any one of the intermediate trays of a trayed distillation column.
SIEVE TRAYS
Fractionating trays consisting of sieve‑like materials, generally perforated plate. The flow is essentially of the dual type, but this character may be reduced by the provision of downcomers.
SIGHT GLASS
Device used to directly show the level in a vessel, boiler, etc. by means of a glass tube.
SILVER STRIP
A very strict corrosion test for AVTUR.
SLACK WAX
See Crude wax.
SLIDE VALVE
A type of valve for controlling or shutting off the flow of catalyst in a continuous regeneration unit.
SLOPS
A term loosely used to denote:
1. Crude oil containing excessive water contamination which must be removed by settling before pumping to the crude distiller.
2. All products which are off‑specification and must be reprocessed before marketing. Such products are for example produced during the start‑up period.
SLUDGE
a) Acid sludge or acid tar: material formed during refining of oils with sulphuric acid.
b) Engine sludge: insoluble product formed from fuel combustion products and from lubricating oils in internal combustion engines and deposited on parts outside the combustion space.
c) Tank sludge: material collected at the bottom of oil storage tanks.
SMOKE POINT
The maximum height of flame measured in millimetres at which a kerosene will burn without smoking when tested in a standard lamp for this purpose.
SOLAR ENERGY
Energy produced by radiation from the sun.
SOLUBLE OIL
Oil which readily forms stable emulsions or colloidal suspensions in water. Used as a cutting fluid in machine work.
SOLUTION
A homogenous mixture of two or more chemically un-reacted fluids.
SOLVENT
A substance, usually liquid, capable of dissolving another liquid, gas or solid to form a homogenous mixture.
SOLVENT EXTRACTION
See Extraction.
SOLVENT/FEED RATIO
On the BDU, the rate of the total amount of butane (predilution and normal) to short residue.
SOOTBLOWER
A device for removal of soot from furnace tubes ‑ to increase heat transfer ‑ ‑ generally using a steam blast nozzle. However, a shot drop system (as on the HCU) does the same job and is sometimes referred to as a sootblower.
SOUR CRUDE
Crude oils containing an abnormally large amount of sulphur and sulphur compounds which break down upon refining to liberate troublesome quantities of corrosive sulphur compounds. This is a relative term.
SOUR GAS
Gas which contains objectionable amounts of contaminants, e.g. hydrogen sulphide and other corrosive sulphur compounds.
SOUR GASOLINE
Gasoline fractions which contain a certain amount of mercaptans and therefore must be sweetened.
SOUR WATER
Water which contains objectionable amounts of dissolved contaminants, e.g. hydrogen sulphide, ammonia, phenols etc.
SPACE VELOCITY
A convenient unit for expressing the relationship between feed rate and reactor volume in a flow process. It is defined as the volume or weight of feed (measured at standard conditions) per unit time per unit volume of reactor or per unit weight of catalyst.
SPADE
A solid plate inserted in a flanged joint to positively isolate one side of the flange from the other. Also called blank, banjo.
SPALLING
Flaking of the surfaces of metals or refractories, leaving new surfaces exposed.
SPARGE
Spray ‑ usually with water (originally a brewers term).
SPARK ADVANCE
In an ignition‑type internal‑combustion engine, the amount measured in degrees of crankshaft rotation, that the spark plug fires before the piston reaches the point of its traverse closest to the cylinder head.
SPECIFIC GRAVITY
The ratio of the weight of a volume of a body to the weight of an equal volume of some standard substance. In the case of liquids and solids, the standard is water, in the case of gases, the standard is hydrogen or air.
SPECIFIC HEAT
The ratio of the quantity of heat required to raise the temperature of a body by one degree to that required to raise the temperature of an equal mass of water by one degree.
SPECTACLE
Or Spec blind. A figure of 8 shaped plate that can be either put to the open or closed position, but always stays in the line.
SPHERE ‑ SEE HORTON SPHERE
SPLITTER
A fractionating tower with overhead and bottoms product streams only.
SPOT
Refers to prices of single cargoes traded on an open market basis. They can vary considerably with the supply/demand situation.
STABILISATION
The process of separating light gases from petroleum or gasoline, thus leaving the liquid stable in the sense that it can be handled or stored with less liability to change in composition.
STABILISED GASOLINE
Gasoline after subjection to fractionation by which the vapour pressure has been reduced to a specified maximum.
STABILITY
Resistance of petroleum products to chemical change. Gum stability means the resistance of a gasoline to gum forming while in storage. Oxidation stability means that the product is stable to oxidation, i.e resists the action of oxidation which forms gums, sludges etc.
STABILISER
A fractionating column designed to make a sharp separation between very volatile components and gasoline ex crude oil, casing head gasoline or pressure distillate, thus controlling the gasoline’s Reid vapour pressure.
STADIS
An anti static additive.
STANDARD PRESSURE
Pressure under which the mercury barometer stands at 760mm, or 30in. (Equivalent to approximately 14.7 psia).
STANDARD REFINERY FUEL (SRF)
A hypothetical refinery fuel with a gross calorific value of 10336 Kcal/kg. Allows all refinery fuel components to be converted to an SRF equivalent based on calorific values.
STAND‑BY
A term used to designate emergency auxiliary equipment which is not used during normal operation.
STAND PIPE
Any pipe that stands proud from a base, e.g. Fireman’s stand pipe for tapping into an underground main or a vessels internal stand pipe to avoid ingress of dirt, scale etc. from the base of the vessel.
STATIC ELECTRICITY
The electricity generated by the relative movement of unlike materials such as oil/pipeline, oil/water, plastic granules/vessel; or by the operation of equipment such as driving belts.
STEAM/AIR DECOKING
In heavy oil furnaces over the period of a process run, the differential pressure across the furnace tubes may increase until it is uneconomical to continue the run. This high pressure drop is caused by carbon built up on the inside of the tubes. We can burn this carbon off by steam/air decoking.
STEAM DISTILLATION
A distillation in which vaporisation of the volatile constituents is effected at a reduced temperature by introduction of steam directly into the charge. Steam used in this manner is termed open steam.
STEAM REFORMING
As used in the reformer for manufacture of H2 ‑ follows general formula CH4 + H20 ‑‑> 3H2 + CO.
STEEL
A solid state mixture of iron and 1‑4% carbon. Can have different structures e.g.
Austenitic ‑ strong, ductile
Pearlitic ‑ low mechanical strength, eventually occurs in furnace tubes when
subjected to flame impingement
Martensitic ‑ Very hard ‑ used in valve faces etc.
STONEWALL
The condition where a centrifugal compressor is delivering its maximum flow.
STRAIGHT‑RUN
A term applied to a product of petroleum made by distillation without conversion.
STRAINER
Alternative term for filter. Used for removal of fine material.
STRAPPING
The measurement of the external diameter of a cylindrical tank by stretching a steel tape around each course of the tank's plates and recording the measurement.
STREAM DAY
Denoting 24 hours of actual operation of a refinery unit; in contrast to a calendar day, i.e. takes into account the units availability factor.
STRIPPING
Removal of the lightest fractions from a mixture. The process is usually carried out by passing the hot liquid from a flash drum or tower into a stripping vessel or stripping section of a column, through which open steam or inert gas is passed to remove the more volatile components of the cut. A fractionating process, closely related to distillation by which undesired volatile components are separated from a liquid mixture by fractional evaporation. The desired fraction is thus purified from lower boiling components. Stripping is generally effected by the introduction of steam, by the reduction of pressure, by the vapour generated in a reboiler or a combination of these. In the laboratory nitrogen is often used as a stripping agent.
STUFFING BOX
A device affording the passage and the length wise and rotary motion of a piston rod, shaft, or some similar moving piece while maintaining a fluid‑tight seal about the moving part.
SULFINOL PROCESS
A process for removing contaminants such as carbon dioxide from gases by contacting with a regenerable solvent. Sulfinol is a three component solvent combining the chemical properties of the ADIP solvent with physical properties of sulfolane and water.
SULFOLANE
Tetrahydro ‑ Thiophene ‑ Dioxide ‑ A component of sulfinol solution.
SULPHATE
A salt of sulphuric acid, e.g. sodium sulphate, Na2SO4, or ethylsulphate (C2H5)2SO4.
SULPHIDE
Any of the compounds resulting from the combination of sulphur ions (S==) with metallic or other positive ions, or organic radicals.
SULPHUR
At NZRC, the final product from H2S removal. A non‑metallic element of lemon‑yellow colour, sometimes known as brimstone. Sold in liquid form to fertilizer works.
SULPHUR CEMENT
Hard, high melting point solid formed by the mixing of refractory brickwork and liquid sulphur.
SULPHUR DIOXIDE
A colourless gas, SO2, a by product of combustion of sulphurous fuels.
SULPHURIC ACID
Traditionally known as Oil of Vitrol. A combination of sulphur trioxide with water (SO3+H20=H2SO4). it is a eavy, strongly oily liquid, an important water treating agent.
SUPERHEATER
Apparatus which imparts heats to a liquid above that required for vapourisation. e.g. as used for adding heat to steam above the saturation temperature.
SURFACE AREA
The sum of the outer and inner surfaces. A porous solid may be said to have two different types of area ‑ one made up of the external, the geometric, or the outer surface of the particle; the other, called the inner, made up of the walls of capillaries, crevices, and cracks in the particle. The sum of these is the total surface area. The ratio of total to outer area is sometimes known as the roughness factor.
SURFACE TENSION
The force exerted by the particles of a liquid at its surface which maintains a continuous surface. The surface tension is determined by measuring the energy required to increase the surface by the unit of area. That property, due to molecular attractive forces and existing in the surface film of all liquids, which tends to bring the volume contained in the liquid surface film into a form having the least surface area.
SURFACRANTS
(Surface active agents) ie trace chemical species which can adversely affect the water shedding properties of fuel.
SURGE
1. An upheaval of fluid in a system frequently causing a carryover of liquid through the vapour lines (see also PUKING).
2. An undesirable condition of unstable flow occurring within centrifugal compressors when the surge parameter drops below a critical value. A very dangerous condition for the compressor, hence the need for surge protection (anti‑surge line).
SURGE DRUM
Vessel used to even out the flow into a unit, as the unit throughput and the feed rate may vary. See also buffer.
SURGE PARAMETER
Indication of nearness to surge condition based on process instrumentation.
SUSPENSION
A heterogeneous mixture of one or more materials ‑ distinct from a solution. The state of a solid or liquid when its particles are mixed with and buoyed in another liquid but are not dissolved by it. A suspension of a liquid in a liquid is called an emulsion.
SWEET GAS
Hydrocarbon gas free from sulphur compounds.
SWEETENING
The process by which petroleum products are improved in odour and colour by oxiding or removing the sulphur‑containing and unsaturated compounds. The conversion of the mercaptans present in sour gasoline into non‑smelling disulphides.
SYNFUEL
A fuel made by the catalytic deoxidisation of methanol using the MOBIL ZSM‑S catalyst. It is blended by NZRC into gasoline or sold as unleaded 92 RON gasoline overseas.
SYNTHESIS
The act or process of making or building up a compound by the union of simpler compounds or of its elements.
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