resolution mass, ultraviolet, fluorescence, and infrared spectrometry and GLC to these hydrocarbons to elucidate many structural features of substituted naphthenic, naphtheno-aromatic, and mono- and diaromatic carboxylic acids. Extension of the investigations by these authors (11OK) revealed many classes of heteroatomic carboxylic acids. These studies show t h a t the “naphthenic acids,” which traditionally have been considered t o be primarily mononaphthenic and alkanoic acids, include a wide variety of compound classes. I n a study of the acids in the diesel oil fraction of Chernuskin crude, Kozlov et al. (69K) converted the acids to sodium salts and treated them repeatedly with aqueous calcium hydroxide until reproducible refractive index values were obtained. The regenerated fractions were studied by infrared spectra, acid number, molecular weight, boiling point, elemental composition, and surface tension. These data plus ndm data on hydrocarbons derived from the acids and the results of dehydrogenation of these hydrocarbons showed that the aliphatic acids had branched chains and the naphthenic acids contained a single cyclopentane ring. Anbrokh et al. (4K) separated the normal alkyl acids from a refinery alkali extract using urea and found that these fatty acids made up 20ojO of the acid mixture; the acids were identified by GLC of their methyl esters. Dicarboxylic acids obtained during oxidation of kukersite kerogen were converted to dimethyl esters and analyzed gas chromatographically by Mannik et al. (81K). Richter et al. (101K) reported the detection and identification of oxocarboxylic and dicarboxylic acids in complex mixtures such as oxidized Green River formation kerogen using reductive silylation and computeraided high-resolution mass spectral data. The acids that act as natural emulsion stabilizers in crude oil were separated and analyzed by Stout and Nicksic (119K)using gel permeation and ionexchange chromatography. Akhundova et al. ( S K ) used the Bjerrum procedure to measure the dissociation constants of the naphthenic acids recovered from oil well water. Starkova and Svest’yanova (127K) published a rapid method for determining the concentrations of naphthenic acid salts in which the sample is dissolved in an alcoholglycerol mixture and titrated with hydrochloric acid. Phenols were the subject of several papers. Diamond (19K) suggests the analysis of normal C1 to Clz p-alkylphenols in lubricating oils by thin-layer chromatography of a chloroform solution on polyamide with sodium hydroxide-methanol as solvent and detection with Fast blue salt B. Traces of phenols in water or acetone were deter-
mined by Cohen et al. (65K)by reacting the solutions of phenols with 1-fluoro2,4dinitrobenzene and GLC (with electron capture detection) of the resulting 2,4dinitrophenyl ethers. Argauer ( 6 K ) reacted sodium hydroxide solutions containing as little as 0.01 ppm of phenols with chloroacetic anhydride in benzene and separated the resulting chloroacetate derivatives by GLC with electron capture detection. Seifert (106K) studied the effect of phenols on the interfacial activity of crude oil by progressive esterification of the carboxylic acids under conditions that left the phenols unmethylated. Selective detection of oxygen compounds in GLC effluents was achieved by Kojima et al. ( 6 7 K ) ; the column effluent is passed over platinum-carbon a t 900 “ C to convert the oxygen to carbon monoxide, and then, after removing interfering gases, over iodic acid a t 120 “ C to convert the carbon monoxide to carbon dioxide. After removal of iodine, the carrier gas and carbon dioxide are passed into a stream of water which is monitored by an electrical conductivity cell. An integrated scheme for the separation of the oxygen and nitrogen compounds in high-boiling petroleum distillates was developed by Snyder and Buell (11SK). The scheme involves ion-exchange and adsorption chromatography on alumina, silica, and charcoal. Using this scheme to prepare fractions which were examined by highresolution mass spectrometry and other techniques, Snyder has examined 400700 O F (IBOK),700-850 OF (114K),and 850-1000 OF ( I d l K ) distillates of a California petroleum. Major oxygen compound types found included pyridones, dibenzofurans, dihydrobenzofurans, phenols, and their benzologs and aliphatic esters and ketones, sulfoxides, and carboxylic acids. Snyder (119K) summarized these investigations in an ACS Petroleum Chemistry Award address. Two methods for characterizing oxygen compounds depend on hydrogenation. Thompson et al. ( I S I K ) developed a microhydrogenation technique which removes the oxygen atom without disturbing the carbon structure; identifications of the resulting hydrocarbons are thus helpful in characterizing the parent oxygen compound. A microreactor gas chromatographic method for identifying oxygen compounds of linear structure published by Krasnoshchekova and Klesment (7OK) depends upon the hydrogenation of the sample with a platinum or palladium catalyst on molecular sieve; the adsorption of the straight-chain hydrocarbons on the molecular sieve and their disappearance from the chromatogram permits distinction of linear from cyclic or branched chains.
Samples produced by liquid-phase oxidation of n-paraffin fractions were analyzed by Brown et al. (18K) by separation on silica gel followed by potentiometric titration, gas chromatography, and mass and infrared spectrometry. Chamberlain (2dK) made detailed correlations of the nuclear magnetic resonance chemical shifts of oxygenated unsaturated aliphatics. Bartonickova (1OK) analyzed the neutral oils from the refining of phenolcresols by petroleum naphtha by comparing the gas chromatographic behavior on columns of Apiezon and PEG 400 supported on Chromosorb. Halogens. The halogen content of highly halogenated organic compounds was determined by Habashy et al. (50K) using polarography after combustion in an oxygen flask. Kainz and Wachberger (61K) determined traces of chlorine in crude oil by combustion followed by nonaqueous potentiometric titration. Neutron activation analysis was used by Elejalde and Albisu (36K) t o determine sulfur and chlorine in petroleum products. Drushel ( S S K ) suggests determination of chlorine by combustion followed by microcoulometric titration.
Analytical and Process Instrumentation W. V. Cropper American Society for Testing and Materials, Philadelphia, Pa. The applications and uses of automatic process analyzers in refineries continue to be emphasized in the technical literature more than the development of new analyzers. This emphasis on pragmatism over research reflects something of a sense of frustration because achieving optimization of process operations has, in too many cases, fallen short of expectations. Analysis instrumentation lies a t the heart of complex control schemes; much attention is therefore being given to making analyzers operate more dependably and to assure that they are installed in the right place and manner. Also, the continuing emphasis on practices is both symptom and partial cause of the more significant trend of control theory and technology to outstrip measurement technology. I n the nature of things, this imbalance will eventually be righted. I n this connection, the January 1970 issue of Instrumentation Technology heralding the 25th anniversary of the Instrument Society of America is most interesting. Staff articles (32L) that review achievements since 1945 and identify unfilled needs list the development of on-stream analyzers among the
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most significant in both categories. Also in the same issue, Professor Williams (75L) goes so far as t o state “The direct conversion (oia a parallel process simulation) of temperatures, pressures and other related variables into computed internal composition variables is a n especially attractive possibility for circumventing the difficulty of directly obtaining such data.” ,4 comprehensive survey by McWilliam (42L) deals with process control by gas chromatography. Although concerned mostly with chemical plant operations, the article contains much information that is directly applicable to petroleum refining. It directs attention t o hardware requirements, including sampling systems, points out special requirements for closed-loop control, and provides information on maintenance and calibration. The 190 cited references make this survey especially useful. Sekanovic and Jagaric (69L)discuss East European use of GLC in automatic control of refining processes. Geschke et. al. (21L) present a comprehensive discussion of the application of gas chromatographs and other process analyzers to computer-aided control of refinery distillation processes. The importance of selecting the right analysis to be performed and the right type of analyzer for each specific analysis is stressed. The trend toward singlepurpose analyzers and away from multistream, multicomponent ones is also identified. The authors also bring out the need to adjust quality-control procedures and standards to take account of the better repeatability of data from on-stream analyzers. ASTN Committee D-2 on Petroleum Products is working t o develop standard methods for validating the results of on-stream analyzers used to control quality of products, notably in continuous blending of gasolines (9L). Elemental Analysis. Rhodes and Mott (54L) devised a continuous analyzer for monitoring hydrogen in process streams, utilizing the X-ray absorption principle. Beta-radiation from a Sr-Y source is directed against an U target, and the X-radiation is picked up by a Te-doped sodium iodide scintillation detector. Because the mass concentration result is affected by the stream’s density, this latter property is measured by absorption of neutrons from a Pu-Be source; a proportional counter is the detector. The two sources and sample cells are immersed in a thermostated oil bath, and a computing network produces the analytical result a t intervals of five minutes or more. A similar laboratory instrument is used routinely in preference to the conventional methods. A rapid, automated laboratory analyzer is described by Merz (45L) for 192 R
determining hydrogen and carbon by combustion. Carbon dioxide is absorbed in amine/DMF and titrated with tributylethylammonium hydroxide; water is converted t o CO2 first by passage over carbon at 1120 “C and then over CuO, to utilize the same titration scheme. H / C ratio can obviously be derived too. An instrument patented by Sanford and Ayers (56L) utilizes coated piezoelectric crystals sensitive to HzO and CO2 (after removal of the water); electronic circuits for frequency comparison allow obtaining the result directly. The fuel-cell type of oxygen detector was described by Sarknas (58L), utilizing two concentric ZrOz electrodes containing Ce and maintained at a high temperature. The differences in O2 content of the test and reference samples produce a millivolt signal that can be calibrated directly in terms of Ozcontent as low as 0.8 ppm. This instrument has been introduced commercially. The use of oxygen analyzers on process and flue gas streams is reviewed by Tipping (68L), who also stresses the importance of the sampling system. For measuring trace amounts of nitrogen in organic samples, Shell (60L) has patented a combination GLCcombustion analyzer. An nitrogen-rich fraction is concentrated a t the top of a molecular sieve column after passing the sample in a COZ stream over hot CuO and Cu in succession; the collected X is swept out by H2; a thermal conductivity detector is employed. Dawson and Cszky (15L) describe a n on-stream analyzer for total carbon in steam condensate and plant wastewater. In this combustion-type analyzer, the sample is oxidized over Pt catalyst in a stream of 02; the resulting COZ is determined by I R ; the sample handling system is also described. Hall et al. (26L) invented a process instrument for monitoring carbon content of beaded catalyst, in which light reflectance of the pulverized sample is compared to that of a reference, producing an electric signal proportional t o coke content; the analysis cycle is about 15 minutes. For measuring carbon content of fluid catalyst, the process analyzer of Kapff and Wright (36L) measures the rate of combustion-zone progress through a heated bed; the rate is faster for carbon-rich samples. Operating intermittently, the catalyst is brought to 1000-1500 “C, then air is admitted. When the combustion front passes a first thermocouple, a timer is activated but is stopped when the front passes a second thermocouple. Continuous determination of sulfur in oil is described by Trost (69L) based on measuring the absorption of X-radiation from a tritium source; density compensation is based on
ANALYTICAL CHEMISTRY, VOL. 43, NO. 5, APRIL 1971
absorption of gamma radiation from a la7Cs source. Accuracy of = l = O . O l ~ oS has been demonstrated during a year of plant operation. Festa et al. (19L) apparently use beta radiation to produce X-rays and gamma radiation for density compensation in a generally similar though more complex device. Hasegawa (28L) discusses a continuous X-ray absorption analyzer for crude oil and fuels, but details of it are lacking. Inoue (3fL) describes an on-line continuous sulfur analyzer for fuels based on X-radiation from 66Fe and beta radiation from 9oSr. The use of 147Pm/ A1 as a radioactive source is described by Novak (49L), employing a laboratory instrument that analyzes 55 samples per shift. Despite the number of sulfur-measuring instruments that have been described in this and previous reviews, none are commercially available as of mid-1970. Maurice et al. (44L) invented a n instrumental method for determining sulfur in gaseous hydrocarbons based on combustion to SO2 and measuring the electrical conductance of the absorbing electrolyte. Rupprecht and Phillips (55L) devised a novel oxidizer-detector system for continuously measuring sulfur in hydrocarbons; this can be used in connection with GLC but requires calibration for each sulfur component. A gas chromatograph specially designed for determining tetrahydrothiophene and dimethyl sulfide in natural gas was developed by Gibbons and Goode (2%). The x 28-inch column is packed with 20% trixylylphosphate on Celite. The effluent is burned in a H-rich flame, producing violet and UV radiation; the sensor is a filtered photomultiplier. Specific Compound Determination. The search for better ways t o determine water goes on unabated. Caldwell (6L) was granted a patent on a device that uses a material capable of fluorescing in the UV region in proportion t o the amount of water reaching it. Caulier and Salesse (7L) measure water in light hydrocarbons by vaporizing the sample in a stream of warm dry gas and converting the water to acetylene which is determined by GLC and flame ionization. Varian Associates (IOL) announced a process analyzer based on N M R , capable of rapid analysis for water. Bloch (4L) invented a GLC scheme employing serial GLC analysis; in the second stage, columns having packings that differ in water-absorbing ability permit cancelling out the effect of coabsorbed hydrocarbons. A British patent was granted Gray (24L) for a gas-phase device for water determination: two Pt electrodes are sealed in a small borosilicate bead which is treated with CrzOl. The electrical resistance between the electrodes decreases with increasing water content and response
time is a few seconds. An automated coulometric titrator was applied by Hoyt (SOL) to the Karl Fischer-type reaction at all levels from a few ppm to 1 0 0 ~ o . A British patent granted to Nippon Oil Company (48L) covers a dielectric-capacitance type instrument in which a bridge circuit balances the sample circuit against a reference circuit; it is suitable for such nonpolar liquids as oil. Crompton and Cope (IQL) meter separate streams of hydrocarbon and a dilute solution of triethylaluminum through a thermostat and u3e the temperature rise when they mix to quantitate water, dissolved oxygen, or low mol w t alcohols in the sample stream. On-line GLC analysis of wet combustion gases is achieved by Archer ( I L ) using a dual-column setup with Portbpak Q and 5A molecular sieve; complete analysis for COZ, CO, Hz, 0 2 , HzO, Nz, CHI, C2H4,and CzH6 is realized. The alkylleads are determined in gasolines by an intermittent-type process analyzer invented by Leisey (4OL); they are reacted with a large excess of silver ion, producing silver which is measured photoelectrically. Podbornov (5SL) automatically monitors acidity during petrochemical processes operating above 100 'C, utilizing metal oxides as electrodes. Compound Estimation by Types. Olefins, as well as other compounds reactive with hydrogen, can be determined in gas streams by a scheme patented by Ayers ( I L ) . Following separation by GLC, the compounds are mixed with hydrogen and passed over Pd-black; the temperature change due to hydrogenation is proportional to the quantity of compound present. Other compound types that can thus be quantitated are aldehydes, ketones, alcohols, ethers, organic nitro-compounds when amines are present, and oxygen. Guillot et al. (25L) independently published an almost identical approach to the same problem, using thermal conductivity detectors. Benz et al. (SL) utilize a wide-spectrum UV source with a narrow-band detector having a pulsed output to measure olefins and aromatics in gas streams; the pulse rate is inversely proportional to concentration. Electro-reactive compounds in a nonconducting process stream are measured by a device patented by Glass and Liederman ( g S L ) , consisting of a porous separator having a detecting electrode in contact on one side and a reference electrode not in contact on the other side. A nonaqueous electrolyte flows past the reference electrode through the separator to the detector; when mercaptans, H B , acids, alkalies, or other such compounds are present, the potential between the electrodes changes proportional to concentration. Kapff (S5L)
patented an apparatus for determining the concentration of ionic contaminants in liquid hydrocarbons wherein the sample stream flows through a labyrinth on one side of a hydrophilic membrane while deionized water flows across the opposite side; the change in conductivity of the water is a measure of the ionic contaminant. The water is recycled over suitable resins. The process is continuous and accurate to parts per million. A novel GLC technique was patented by Universal Oil Products Co. (7OL, 7 l L ) to measure nonnormal hydrocarbons in liquid streams. The molecular sieve column is saturated with n-alkanes and the sample stream is injected a t 1-minute intervals; the n-alkanes are not resolved and produce a n elevated base line on which the peaks for branched alkanes, aromatics, or naphthenes are superimposed. The technique has also been applied to the analysis for HzO, COZ, CZH4, and C3He. Usatenko and Galivets (79L) describe a continuous conductimetric method for determining organic sulfur compounds in hydrogen-rich gases, based on the change of electrical conductivity of a very dilute solution of Cu-acetate by reaction with the HzS that results from hydrogenation of the sulfur compound. It is said that this device is suitable for continuous control. I n a new liquid chromatograph described by Chizhkov et al. ( I % ) , a standard GLC instrument is used as a detector for volatile and slightly volatile constituents. Analysis of Light Hydrocarbons. Permanent gases and hydrocarbons through pentane are measured by Kolb and Weideking (S8L), utilizing adsorption and partition-type GLC columns in a dual channel series-parallel arrangement with an automatic columnswitching system. The general principles have been rather widely employed, using separate chromatographs. The suiccess of the system here described hinges upon a specially designed fourway valve, the features of which are described. A comprehensive system for sampling and analyzing theentire product from the pyrolysis of hydrocarbon feed stocks to produce ethylene is described by Leitner et al. (4lL). A conditioner section separates gaseous products, water, gasoline, and fuel oil; each stream is continuously measured or weighed. The gas stream is analyzed by GLC for all constituents; the HzO is measured by volume. Density of the gasoline and fuel oil streams are measured continuously. The apparatus is designed for field use and has demonstrated its suitability for making material balances and yield determinations from individual furnaces.
Physical Properties. Two process analyzers for measuring the cloud point of distilled fuels are discussed by Nee1 and Chassagne (47L) in considerable detail. Their principle of operation, patented by Shell Internationale Research (6115)is the detection of turbidity as the sample is cooled; by using polarized light only wax crystals are seen, water crystals being transparent. A commercial version of this instrument is available. Simpson (6SL) also of Shell Internationale Research, has patented another process analyzer for determining cloud or crystallization point, in which two thermocouples located a t different distances in the sample above a cooling plate display a constant differential temperature until crystallization begins to occur, releasing heat. At that point, the temperature is recorded and a new sample is introduced. The complete analysis cycle is about 8 minutes. An instrument of this type is also commercially available. The density of liquid hydrocarbon streams is monitored by Rhodes and M o t t (54L) by passing the sample stream through a thermostated cell, where it is exposed to neutron flux of 1.9 x lo7 neutrons per sec from a 10Curie Pu-Be source. A proportional counter measures the neutron transmission, which is proportional to density. A simple computer circuit produces a readout a t intervals as short as 5 minutes. Harangozo (27L) describes a laboratory instrument, now commercially available, for measuring dropping point of waxes and greases or melting point of asphalts. The sample, solidified in a constricted tube with an open bottom, is heated a t a predetermined rate until a drop falls and is detected photoelectrically. The temperature is displayed and recorded automatically. The fouling characteristics of petroleum distillates are evaluated in an apparatus patented by Cook ( I S L ) . The sample is heated and cooled while its electrical conductivity is continuously measured. The temperature a t which the conductivity changes is a n index of the stability of the sample, hence an indication of its fouling tendency and the relative effectiveness of fouling inhibitors. Joy and Jenkinson (S&) summarize various methods for on-line measurement of particle size. The attenuation of ultrasound (above 30 KHz) is a technique potentially useful for concentrations below 0.4y0 and in the size range of 10 to 400 pm. Ultrasound-echo measurements have few theoretical limitations but require advanced electronic equipment. A calibrated hydrocyclone may be used for particulate classification; if the densities of medium and particles can be assumed constant, and the temperature and flow rate can be kept
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constant, it is possible to devise a control system. Another possibility is the comparison of two X-ray beams, one of which is insensitive t o particle-size variations and another that is sensitive; the differential signal is free of compositional effects and responsive t o small changes in size distribution. However, the sensing head (usually employing GI1 tubes) must be specifically designed for each kind of solid. Isotopes can be used as X-ray sources, but a high-voltage supply for the detector is usually required. Most of the applications discussed are taken from the minerals-processing industry but some are analogous to petroleum processes. Nakajima et al. (46L) describe two new instruments for on-line measurement of particle size, based on elutriation. Average particle size can be determined every fifteen seconds or so; cumulative size distribution is measured in another instrument as frequently as every minute. Both articles reveal the increasing importance of monitoring particle size, distribution, and concentration as well as the difficulties t’hat attend making such measurements on-line. An automatic pour point tester, patented by Esso Research & Engineering Co. (18L), has been commercialized. I n this instrument, a temperature-sensing disk is immersed just below the surface of the oil sample and is partially rotated periodically while the sample is being cooled thermoelectrically. Solidification of the oil prevents rotation, thus indicating the pour point. Each test requires as little as 4 minutes; reproducibility is about 2 O F . Shell Internationale Research (6%) patented another pour point instrument, in which the oil sample is placed in a test cell that has a flexible membrane bottom capable of being displaced about 5 mm by a moveable support plate. Sample temperature is measured by a thermocouple and is recorded as long as there is electrical contact between the membrane and the support plate. When solidification of the oil prevents the membrane from following the support plate, the pour point has been reached and the test is terminated. The Vapor-Liquid ratio of motor gasolines has become nearly as important a parameter as Reid vapor pressure. Stormont (66L) describes the automatic control of gasoline volatility during in-line blending by means of a commercial instrument developed by Union Oil Company, which expresses volatility in terms of V / L ratio at constant temperature and atmospheric pressure. A somewhat similar device patented by Webb (74L) heats the incoming sample to a constant temperature; the flow rate of the vapors produced is measured volumetrically 194R
while the liquid in the separating vessel is held at constant level by means of a positive displacement pump. The liquid withdrawal rate is thus measured, and a n electrical proportioning circuit calculates and displays the vaporliquid ratio. Plucker (69L)determines the V / L ratio of gasoline by expanding a constant volume of sample into a thermostated chamber closed by a moveable piston. The position of the piston when equilibrium is reached is proportional t o the total vapor volume, hence to the V / L ratio. An electrical circuit detects the piston’s position and produces a signal compatible with automatic control instruments. This instrument is being commercialized. Cheng and Davis (11L)have modified a commercial coaxial-cylinder rheometer for automatic on-line measurement of Newtonian and of non-Newtonian viscosities. The instrument is programmed t o change speeds automatically and to record torque-speed data on punched tape that a digital computer converts to stress-shear rate information. An automatic laboratory version of the instrument has been used to obtain stress-shear rate on lubricating oil, also. Sudakov et al. (66L) describe a capillary viscometer for continuously monitoring the viscosity of refinery process streams. Precautions are taken to achieve constant flow rate and maintain laminar flow a t the capillary entrance. A temperature-compensating device allows temperature t o vary over a 5 “ C range yet give repeatability of h0.4 cSt; accuracy is A 2 cSt. The application of two models of a commercial process viscometer is described by Walter (7SL). One model operates a t relatively low temperatures and is limited to low-viscosity, wax-free streams. Another model is used for. viscous, wax-containing oils. Besides measuring absolute viscosities over the range 0-2500 cp, other applications include measuring viscosities at 100 and 210 O F on the same stream, utilizing a small analog computer to calculttte viscosity index. The melting-point of ash from lubricating oil additives is determined by a n electronic recording apparatus devised by Suleimanova et al. (67L). Only 50 mg of ash is required, and each determination requires about 30 minutes. Good agreement with the Seger cone method was obtained. Thermal analysis of polymers and bitumens is accomplished by a sensitjive analyzer developed by Eggertsen et aZ. (17L). It consists of a small sample furnace joined directly to a high temperature flame ionization detector; the volatilization patterns of various organic materials can be determined, as well as quantitative measurement of volatiles produced and of decomposition rates.
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Titration Instruments. Helbig (29L) clovers the amperometric determination of 0, N, cyanide ion, and chromic ion in liquid streams and of SO2 in process exhaust gases. He details the conditions required for the installation of this type of process analyzer and reviews the pertinent theory of amperometric methods. An automatic coulometric titrator patented by Johansson (SSL) has two vessels connected by a conducting bridge; the reference vessel contains a n electrode immersed in a reference liquid or in a portion of the stream sample. The working vessel contains the working electrode, stirrer, indicating (pH) electrode and the sample t o be titrated. The indicating and reference electrodes are connected to the input of a differential amplifier, the output of which conkrols the generating circuit. The time integral of the differential signal is the measure of the component sought. A version of this instrument was also used to measure SO2 in air at concentrations well below 1 ppm; the SO2 was captured in the second vessel, and measurements are essentially continuous. An automatic titrator for the Karl Fischer determination of water in organic liquids was developed by Wuschke and Stewart (76L). The flow of K F reagent is automatically controlled in relation to the potential between the indicator electrodes; a timing circuit automatically delays small additions of reagent while transitory end points disappear. Applications. A sampling system for Platforming process effluent that reduces the stream pressure from 20 t o 2 kg/sq cm, removes suspended matter, degasses and dehydrates the stream, and meters it to a n on-stream analyzer is described by Kosov and Mikheeva (S9L). Markovs et al. (&L) surveyed the adaptation of commercially available analytical instruments for plant use in determining a wide variety of impurities in streams from such adsorption processes as desulfurizing ammonia plant feeds, drying cracked gases, and purifying LPG. Petrovic (61L) reviewed applications of GLC t o petroleum processing in Eastern Europe, emphasizing the use of these instruments in automatic feedback and feed forward control systems. Tipping (6%) describes how oxygen analyzers are used for monitoring process and flue-gas streams. While magnetodynamic instruments are generally the most accurate ones, precision is dependent upon the type of sampling system cmployed. Kellogg et al. (37L) surveyed five years of experience with a “pushbutton” octane test engine and determined that this semiautomated instrument improves laboratory efficiency by reducing the time needed to make a Motor or Research octane rating by
SO-SO%. With two of these test engines, one man can make four ON determinations in the time formerly needed for a single measurement. The resulting increase in precision allows optimizing octane specifications with a resulting saving in processing costs. Automatic control of a fractionating column producing an aromatic precursor stream is based on GLC analysis of the stream sample following catalytic hydrogenation, according to Boyd (6L). The automatic removal of dissolved nonvolatile substances from liquid process sample streams to be chromatographed is described by Cayanus and Villalobos (8L). A special 10-port valve simultaneously isolates the sample valve from the column and flushes the sample vaporization area with a measured amount of solvent, which is discarded to a separate vent. Smith and Villalobos (64L) utilize a somewhat similar but simpler scheme to overcome the accumulation of high-boiling residues in the inlet of a process stream GLC instrument. Steam or a suitable solvent is automatically used in each analysis cycle to remove any residue from the tubing section that forms the analyzer inlet. To pyrolyze samples of polymers and other high-molecular-weight samples prior to GLC analysis of the products, Folmer and Azarraga (BOL) employed a pulsed ruby laser. The resulting chromatograms were simpler and allow greater distinctions to be made between similar substances. Pendry (60L) developed a “StopStart” automatic gas chromatograph for handling 1- to 10-pl samples of multicomponent mixtures; when a peak is eluted the gas flow is stopped and the pressure is equalized to atmospheric, allowing the use of a conventional I R spectrometer to provide high-resolution spectra. A mass spectrometer can be similarly used to characterize the eluted material. A versatile high-speed process chromatograph was described by Sanford et al. (67L), capable of providing 14 component analyses in 4 minutes on each of 8 process streams. Experience with this and similar instruments has shown them to be highly reliable despite their complexity; they are particularly applicable to the automatic control of distillation columns for light hydrocarbons and petrochemical feed stocks. The current trend in design and application of process chromatographs appears to be toward simpler instruments to measure a few key components in only a single stream. Diets (16L) describes a computer-controlled system comprising seven high-accuracy, single stream chromatographs. The computer supervises the operations of the chromatographs, including the operation of sample valves, backflush, and
injection of standard samples. It also performs the needed calculations, employing teletypewriter printout and automatic alarm messages. Laboratory Automation. Linking advanced and automatic laboratory instruments to computers for the purposes of maximum utilization of the instruments and to avoid laborious calculations of results is a major trend. There are as many detailed schemes as there are practitioners. What is becoming increasingly clear is that large analytical service laboratories and quality-control centers can thus achieve marked increases in service capability and data-handling efficiency. Because laboratory automation of this type has entailed little development of instruments so far, a review of the literature is outside the scope of this section. It is to be expected, however, that the wedding of computers to instruments will soon bring forth a new generation of advanced automatic laboratory instruments.
Miscellaneous R. W. King Sun Oil Co., Marcus Hook, Pa.
Contamination Control. This material is intended primarily to cover methods for the analysis of contaminants in petroleum products and in the immediate refinery environment. Although some papers of wider scope are included, it does not attempt to deal comprehensively with the general analytical problems of air and water conservation that may arise from the transportation, storage, and use of petroleum products. These are better handled as a part of the broader subject of environmental pollution. Chovin ( 1 4 N ) has reviewed methods for the analysis of many of the common pollutants of industrial atmospheres. Procedures for sulfur dioxide, hydrogen sulfide, dusts, aerosols, oxides of nitrogen, ammonia, ozone, fluorine compounds, hydrocarbons, tars, carbon monoxide, nitrogen peroxide, and aldehydes are covered. Bethea and Meador (6121) have recommended a chromatographic system of three columns for the analysis of a mixture of nitric and nitrous oxides, nitrogen dioxide, chlorine, hydrogen chloride, fluoride, and sulfide, sulfur dioxide, and carbon dioxide in air. Single columns and tandem combinations are suggested for less complex mixtures. The use of infrared spectrometry for the analysis of ten of the more common gaseous air pollutants, including benzene, sulfur dioxide, hydrogen sulfide, propane, acetylene, and some of their mixtures, has been reported by Steger and Kahl (67iV). The determination of the oxides of sulfur and hydrogen sulfide in both
stack gases and industrial atmospheres has received a great deal of attention. The determination of atmospheric concentrations of sulfuric acid aerosol was described by Scaringelli and Rehme (6ZM). Schneider (53111) has developed a simple portable apparatus for determining sulfur oxides in flue gases. The sulfur trioxide is trapped in a heated sodium chloride filter, the sulfur dioxide absorbed in hydrogen peroxide solution, and the sulfur oxides are determined as sulfuric acid by titrating with sodium hydroxide. Vasil’eva et al. (6251) use gas chromatography to determine hydrogen sulfide and carbon dioxide in refinery gases. Adams ( 2 M ) described a n automated, sequential subtractive sampling system for the determination of sulfur dioxide, hydrogen sulfide, methanethiol, dimethyl sulfide, and dimethyl disulfide. The gases are analyzed by coulometric titration with bromide ion before and after passage through each subtraction reagent. Two systems that are capable of monitoring hydrogen sulfide in stack gases have been reported in the literature ( 1 O M ) . I n the device developed by Murray and Risk, the sample stream is divided into two parts and the hydrogen sulfide in one catalytically oxidized to sulfur dioxide. Comparison of the ultraviolet spectrum with that of the unoxidized stream gives direct data on the hydrogen sulfide content. The analyzer developed by Thoen and Haas is essentially a modified electrolytic titrator in association with a sampling probe, and has a sensitivity of bet’ter than 5 parts per billion a t 700 O F . The problems of monitoring sulfur dioxide concentrations in stack gases have been reviewed by Kotnick and Scheck (34M). They conclude that instruments based on wet chemical methods have serious drawbacks and describe a number of commercially available monitors based on other detection principles. Jackson and coworkers ($OM) monitor the concentration of sulfur trioxide in stacks with a device that operates by absorbing the sulfur trioxide in aqueous isopropanol, reacting the sulfate ions with solid barium chloranilate, and determining the acid chloranilate ion photometrically. Efforts to reduce atmospheric contamination have resulted in the enactment of a solvent law in Los Angeles County, termed Rule 66. It places limitations on solvent emissions and on solvent formulations used within its jurisdiction, and as a consequence, creates some analytical problems. MacPhee and Kuramoto (4SiV) describe two procedures developed for use in conjunction with the rule. For emissions, a total combustion method is used. For solvent formulations, a column-chromatographic screening is first performed to measure types of
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