Application of Machine
Four of the papers presented at the Division of Petroleurn Chemistry, 132nd Meeting,
Transmission and Remote Calculation of Mass Spectrometer Data C. H. MIHM, L. W. POLLOCK, and R. 0. SHELTON Research and Development Department, Process Development Division, Phillips Petroleum Automatic computing facilities available for calculation of mass spectrometer data were located about 350 miles from the mass spectrometer. A data-transmission system between the computer facilities and the mass spectrometer was installed. The calculation time for samples of mass spectrometer data has been reduced from several hours to about 1 minute per sample b y use of the automatic computer. Transmission of the mass spectrometer data, calculation of the sample composition and related engineering calculations, and transmission of the results to the spectrometer laboratory are handled routinely b y nontechnical personnel. Calculations can b e made available to plant engineers within 24 hours after sample analysis. The accuracy of results has been increased b y automatic computation.
P
R-ithin the petroleum and petrochemical industry have increased requirements for analysis of process streams. The laboratory mass spectrometer is a fast and versatile instrument for providing accurate compositions for many of these process streams. The mass spectrometer ionizes gases to produce a series of ions of varying mass. The ions are separated and the concentration of each ion mass number is determined. A set of simultaneous linear equations is obtained (3) by combining calibrations obtained from the “mass spectrum” for each component in the sample and the ‘hiass spectrum” for the unknown sample. For a sample containing n components, a set of n equations with n unknowns must be solved to obtain the sample composition. The normal output from a mass spectrometer is a strip chart tracing, which ROCEBS DEVELOPAIEXTS
874
a
ANALYTICAL CHEMISTRY
plots the peaks occurring a t specified ion mass number ( 1 , 8 ) . The strip charts are read manually and recorded. This manual reading and subsequent solution of simultaneous equations have been the delaying factors in obtaining mass spectrometer analyses. The mass spectrum for a typical sample can be obtained in a few minutes. Nanual reading of the peak heights and subsequent calculations often take 1 to 2 hours per sample. Further computations to obtain process yields. conversion, or other process information derived from the compositions increase the time required to obtain the desired information from the mass spectrometer data for process control and evaluation. An increase in the number of mass spectrometer analyses a t Phillips facilities in the Borger, Tex., area necessitated more rapid methods to obtain the peak height reading, perform the composition calculations, and complete the related extended engineering calculations. The follo~vingchanges were made in processing the. mass spectrometer data. The mass spectrometer was equipped with a Spectro-Sadie, a n analog to digital converter which automatically converts the peak heights into digital form, which are then recorded by a n automatic typewriter and punched into I B N cards. A program m s developed t o calculate the sample composition and to perform other extended computations on a n automatic digital computer. The automatic computing facilities available for this purpose were located some 350 miles from the mass spectrometer at Borger. As the mass spectronieter computations alone did not justify the installation of separate computer facilities a t Borger, a datatransmission system was needed be-
Co., Bartlesville, Okla. tween the computer facilities in Bartlesville and the mass spectrometer laboratory. For the past 18 months a Datatron, a medium-size internally programmed digital computer, has, been used for the calculations. The calculation time, including extended calculations, has been reduced from several hours, in many cases, to about 1 minute per sample by use of the automatic computer. EQUIPMENT
Mass
Spectrometer
Laboratory.
Figure 1 shows the flow of information through the equipment in t h e mass spectrometer laboratory. The information flons from t h e mass spectrometer t o a Spectro-Sadic, where i t is digitalized and then punched in IBM cards. The cards are next manually loaded into the card feed of the transmitter (indicated by dashed lines on the floiv chart). Information on the cards is then transmitted to the computing center via a leased Teletype line for computation. Figure 2 shon-s the flow of computed results. After the analyses have been computed, the results are transmitted to the mass spectrometer laboratory and automatically punched into IBlL cards. The information on the punched cards is listed n i t h a standard IBLI line printer to yield the final printed results.
SPECTRO-SADIC. The Spectro-Sadie is a standard electronic device manufactured by Consolidated Electrodynamics Corp., Pasadena, Calif. It receives analog data directly from the mass spectrometer and converts it into digital form. The digital data are printed on a n electric typewriter along with simultaneous punched card output. The punched cards are produced through an I B N Type 523 summary punch. The Spectro-Sadic automatically scans peaks and records peak
TRANSMISSION EQUIPMENT CENTER
V I A TELETYPE PUNCH
rq '\
2I-I TYPEWRITER
Figure 1.
'
TO COMPUTER CENTER VIA TELETYPE TRANSMISSION LINE
PUNCH
PRINTED RESULTS
Figure 2. Flow of results through mass spectrometer laboratory
must he solved for each compound analyzed, a sample containing 20 compounds requires solution of 20 siniultaneous equations. The unknovins in the equations are the concentrations of the various compounds. and tlie coefficients of the unknowns are constants predeterniiried by a calibration procedure. A symbolic mass spectrometer matrix for four components is shown in Figure 4.
Data flow through mass spectrometer laboratory
Y
TAPE
FROM SPECTROMETER LABORATORY VIA TELETYPE TRANSMISSION LINE
CARDS
TRANSMISSION LINE
CARDS
COMPUTER
++ ++ + A,4X< = + A*,X* P+ A32X2 ++ r z d , ++ PB A,,X1 + P4 d'!-llXl
AXX1
dl2X2 1122x2
A31X1
A4J2
REPRODUCER
Trl .-
SPECTROMETER
{
~
~
B
o
~
~
T
o
R
Y
TELETYPE TRANSMISSION LINE
Figure 3.
Data flow in computer center
heights a t a rate of approximately one every 10 seconds. Saniple and peak identities are punched simultaneously with actual peak values. The peak readings are punched as three-digit numbers plus two digit scale or multiplying factors. I B M TRASSCEIVER. The transmitting and receiring equipment consists of a n International Business Machine Transceiver. designed t o transmit information from punched cards over teletype or telephone lines, or by microwave. The system utilizes a standard 60-word-per-minute leased Teletype circuit. After each digit is received and punched a t the receiving station, a check signal is relayed back to the sending station to detect line errorb. The transmission (and receiving) speed of the Transceirer is 240 digits per minute. Data for a typical mass spectrometer sample might require 1.5 niiriutes for transmission (usually unattended). A standard Model 015 Teletype senderreceiver supplements and coordinates the transceiving equipment. ALXILIARY EQUIPMEST.Standard I B J I card equipment is used for manual key punching and for card tabulation. The key punch is used to punch identifying and supplementary information in cards from tlie Spectro-Sadie. An alphabetical line printer prints out final ansners and yields a printed, fully identified form in multiple copies. Computer Laboratory.
Figure 3
indicates t h e information flon in the computer iooni. X a s s spectrometer sample d a t a a l e received by t h e Teletype from t h e mass spectiometer laboratoiy, and, on punched cards, processed in the computer, and t h e conip u t t d iesults a l e punched in new cards. The information on the answer cards is transmitted back to the mass spectrometer laboratory. CovPuTLR. The Datatron, a medium-speed, magnetic-drum, electronic computer manufactured by the Electro Data Division, Burroughs Corp., is used for the Inass spectrometer calculation. The installation includes paper tape input-output, punched card input-output, electric typewiter and line printer output. automatic floating decimal point indicator, and magnetic tape auxiliary storage. I t i drum storage capacity is 4080 words. AUXILIARYEQUIP~IEST.After the answer cards have been produced by the computer, alphabetic identities are added to these cards. This step utilizes niaster decks and standard I B J I sorting and reproducing machines.
CALCULATION METHODS
Analyses. The basic problem involved in mass spectrometer calculations is the solution of a set of siniultaneouc equations. As one equation
P I
-413x3
-423x3 -433x3
= 1 1 3 4 x 4 = -444x4 =
X , = concentration of component z A , , = peak contribution of pure coniponent J to peak z as determined by calibration P , = total peak reading Figure 4.
Mass Spectrometer Matrix
The coefficient's of the unknon-ns are usually referred to as the calibration mat,rix. I t is semipermanent, with nen- calibrations required only \ h e n the characteristics of the mass spectrometer itself change. Ae t,he calibration niatris changes infrequently and many samples are computed from the same calibration! it is well to invert the calibration matrix and perform a matrix by rector multiplicatioii to obtain answers; calibration matrices are usually \yell conditioned and require no special precaut,ions Gr techniques to invert. Usually standard elimination trchniques may he used for the matrix inversion. Once a matrix is inverted, the inverse is filed for use with all sample analyses of that specific type. The pcak readings for a giwn sample are multiplied by the appropriate calibraticn inverse to yield the saniple coniposit'ion. The compositions thuc obtained are unnormalized-that is. t'hej- probably do not total 100%. These compositions are then normalized slid are usually calculated and reported on an air- and water-free basis. At t'his stage, the actual analysis calculations are complete. Special Calculations. Because saniple analyses are usually used in further computations, the mass spectrometer routine can be extended to include VOL. 30, NO. 5 , M A Y 1958
875
Table I. Sample Tabulation of Mass Spectrometer Results"
Hydrogen Methane Ethylene Ethane Air Propylene Isobutane Propane Butenes n-Butane Pentenes Total Air Gas specific gravity 0
Mass 002 016 026 030 032
(0512 31 effluent gas refining) Unnorm., Mole % Mole % Wt. % 8.38 9.58 0.45 13.86 15.84 5.93 2.33 2.66 1.74
0*2
043 044 056
058
070 ... 032
1.01
3.40 9.34 34.67 1.56 14.22 1.37 0.76
90.90 3.74
1.15
0.80
10.67 39.62 1.78 16.25 1.57 0.87 99.99 3.74 1.477
10:49 53.84 1.83 21.31 2.13 1.42 99.94
...
Sample Card KO. 01
02 03 04 05
06 07 08 09
10 11
12
13
14
NO.
6400 6400 6400 6400 6400 6400 6400 6400 6400 6400 6400 6400 6400 6400
Headings not included in original tabulation.
these special calculations. Calculations routinely performed a t Phillips on a single-sample basis-conversion of composition units, specific gravities, gross heating values, and net heating values-involve a relatively minor extension of the mass spectrometer routine but represent a considerable manpower saving. ilnalyses of plant streams are often used to calculate plant material balances, yields, and other process factors. The Phillips mass spectrometer routine includes some of these calculations. These computations usually require several sample analyses as load data. One such calculation for an ammonia plant requires the analysis of four samples and performs material balances, yield calculations, efficiency determinations, and other calculations, performed automatically as a feature of the basic mass spectrometer routine. Similar calculations are being performed for two other petrochemical plants in the Borger area. COMPUTER ROUTINE
For maximum efficiency, a computer routine should require little manual intervention, incorporate checking features, and require no technica! manpower for its operation. The mass spectrometer routine includes all three features. To ensure automaticity, all mass spectrometer calculations are performed by a single general-purpose routine which will handle any number of components up to 20. Each sample fed to the computer contains identity codes which are used by the computer to select the proper subroutine specifying the calculation sequence to be performed. Checking features in the routine include a check to ensure use of the proper calibration inverse, and a check to assure that the 876
0
ANALYTICAL CHEMISTRY
data are in proper sequence. A printed description is made of any error that is detected. As a result of the many computational alternatives, the machine routine is lengthy, requiring more than 4000 computer storage locations. Inversion of calibration matrices is a separate operation. Calibration data are fed into the computer from cards. The inverse is computed and punched in paper tape ready for the main routine. About 70 such inverses are contained in the present library. Data to be calculated arrive in the computer room in the form of punched cards via the transmission equipment. Each sample is identified by number and by codes to indicate the required calculations. The cards also contain peak readings and scaling factors as punched from the Spectro-Sadic. They are sorted to allow all samples of a specific type to be run a t the same time, and are placed in the computer input card reader. The main mass spectrometer routine and the appropriate calibration inverse are loaded into the computer. The computer is placed in continuous automatic operation. The mass spectrometer data are then automatically loaded and computed, with the operation continuing until all samples have been calculated. Computer time per sample varies from 20 t o 60 seconds, depending on the sample size and the special calculations performed. The major portion of this time is required for input and output. All the computer room operations are handled by nontechnical computer operators. A flow diagram of the machine room procedure is shown in Figure 3.
spectrometer data has become completely routine. Transmission of the data to the computing center, calculation of the sample compositions and related engineering calculations, and transmission of the results to the spectrometer laboratory are acconiplished without attention from technical personnel, except when revisions are made in the computer routine The number of routine mass spectrometer samples has doubled since the data reduction and computation system was established. This increased sample load rrould have required the addition of several personnel to the spectrometer laboratory staff for data reduction and calculations. The calculations for the normal sample load of about 75 per day, including related engineering calculations, require less than 1 hour of computer time. The accuracy and dependability of results have also been increased by automatic computation. The rental charges for the computer and related equipment, prorated on the basis of computer usage, average about 50 cents per sample. Transmission equipment and line rental also average about 50 cents per sample. The calculation of mass spectrometer analysis is usually scheduled once in each 24-hour period in the computer center. The frequency of calculation largely establishes the time between sample analysis and availability of calculated results. The compositions obtained from the mass spectrometer data are available at the mass spectrometer laboratory and to the plant engineers within 24 hours. These data are utilized in the commercial plants for process control and evaluation. Typical results provided to the plant staff are shown in Table I. Multiple copies of these results are obtained directly from the line printer, thus eliminating manual reproduction errors. The success of the mass spectrometer calculations and the benefits to the plants as a result of the automation of these calculations have developed much interest in further computer applications. LITERATURE CITED
(1) Bronq, R. A., Melpolder, F. W., Division of Petroleum Chemistry, 127th lleeting, ACS, Symposium 32, pp. 25-42, April 1955. (2) Dudenbostel, B. F., Jr., Priestley, William, Jr., ANAL. CHEM. 26, 1275-8 (1954). (3) Faden, B. R., Applied Science Department, International Business Machines, Tech. News Letter No. 10, pp. 165-72, October 1955.
RESULTS
The automatic computation of mass
RECEIVED for review September 3, 1957. Accepted February 3, 1958.
