KNOW-HOW ECONOMICS This symposium on Know-How Economics i s indicative of the ever deeper and wider interest in chemical engineering economics. It was suggested by the increasing use of the term know-how. While originally “know-how” applied to that intimate process knowledge derived from extensive operating experience, it has now broadened to mean that organized knowledge concerning the manufacture and sale of a chemical which is necessary to its chemical success. Know-how thus includes knowledge of the things to be done and those to be avoided; it is the knowledge of use and application as well as the ability to produce economically. Know-how has its origins in the research laboratory; it i s enlarged in the pilot plant, comes to maturity in full scale manufacture, and receives its final economic finishing and refinement in the sale and use of the products. Know-how is obviously valuable and equally obviously costs money to acquire. This symposium i s believed to be the first public discussion as to the costs involved in acquiring knowhow. It i s too much to expect that this pioneering effort can give the definitive statements on these matters. Rather it i s the purpose to make a preliminary exploration of know-how economics with the hope of stimulating discussion and further study of this important phase of chemical engineering economics, JAMES H. BOYD, Chairman
OTHER ARTICLES Costs in Developing Process Know-How J. S. Rearick , , Process Know-How through Licensing Gustaf Egloff , Costs in Developing Marketing Know-How Ralph L. Ericsson and Lester E. Johnson. ,
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Importance of Know-How in
Chemical Development A. W. FLEER, Shell Chemical Corp., New York, N.
987
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The Symposium on Know-How Economics was a presentation o f the ACS Division o f Chemical Marketing and Economics at the 726th Meeting o f the American Chemicol Society, N e w York, N. Y.
Y.
A. J. JOHNSON AND C. R. NELSON, Shell Developmenf Coo, Emeryville, Calif.
Information is presented to account for the rapid increase in industrial chemical research expenditures over the past few years. Although licensing is a means of minimizing research expenses and shortening the time required to complete process developments, the most important source of information on which to base such improvements is one’s own research and development know-how on related processes. As an example of the utilization of ,know-how and the savings afforded by its use, the Shell ethyl chloride commercial process development i s described. A research idea to integrate the substitutive chlorination of ethane with the hydrochlorination of ethylene for the production of ethyl chloride appeared to have considerable merit for application in a new plant projected for the Associated Ethyl Co., Ltd., of Great Britain. By utilizing know-how accumulated from previous development and design work on the chlorination and hydrochlorination processes at the Emeryville Research Center of the Shell Development Co., the assigned project was completed within the desired 12-month period. It has been estimated that a project of this complexity carried out in the absence of such knowhow would have required at least 3 years for completion.
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KNOW-HOW ECONOMICS
T
HE ever-mounting cost in time, manpower, and money re-
quired for present-day chemical development places a premium on complete utilization b y management of all tools that may shorten t h e task of completing assigned projects. The manner in which research and development have become so costly can be established although such findings provide few clues toward means of minimizing the effort. New processes may be brought to successful operation in the shortest possible time and with the most effective use of money and manpower through knowhow-the complete utilization of accumulated knowledge and skills in the fields of both exploratory and bench scale research, pilot plant investigation, process design, and commercial plant operation. The cost of industrial research has been increasing at a staggering rate (Figure 1). For many years the chemical industry classification provided the largest segment of industrial research, on the order of 20% of the total. However, in the last few years, because of extensive governmental support t o aeronautical and electrical research, the chemical industries now provide little more than 10% of the total or approximately $300,000,000 per year. The over-all industrial research expenditure has been made possible by a rapid increase in the number of scientists and engineers employed (Figure 2). Almost as significant as the increase in research workers is the greatly increased cost per professional scientist or engineer. As shown in Figure 3, the annual average cost of a professional in industry has increased from $6300 in 1927 t o $21,500 in 1952. Although a large part of this increase is due t o inflationary forces, it is also influenced by a material shift in the fraction of research effort performed by each professional worker. T h e ratio of professional employees to total research workers has declined from 0.6 in 1927 t o 0.4 in 1952. The unit cost of a research worker, however, does not completely explain the increases noted. A number of forces have combined to increase the complexity of research projects over the past years. It is possible t o obtain some measure of the increasing complexity of process development by referring to past experience. It is obviously impossible to compare identical projects, but some typical examples taken over a period of years give some indication of the changes a t Shell's Emeryville Research Center. -4s shown in Table I, in the period 1933-38 pilot plant developments averaged 14 man-years, but in the period 1944-48 this had increased to 50 man-years per project. And when one examines figures t h a t include not only the pilot plant development but also the research prior to it and the engineering effort that followed, the total manpower utilized per project increased from 55 man-years in the period 1928-38 to 160 man-years in the period 1946-53.
Table 1.
Chemical Project Manpower Requirements NO.
Period 1933-38 1944-48 1928-3 8 1939-45 1946-53
Projects Pilot Plant Investigations 16 11 Commercial Projects 24 13 26
Man-Years Project 14 60 55 125 160
One may then ask what are the factors that have contributed t o this greatly increased research cost, both in manpower and dollars. One of the reasons for increased research expenditure is the increased demand for chemical products. The petrochemical field with which Shell Chemical is concerned has increased its output manyfold in the past years (Figure 4). Since the cost of chemical research has averaged approximately 3% May 1955
5,000~
z b3
100
50
///
10
1926
'30
'34
'38
'42
'46
'50
'54
Year
Figure 1.
Research performed by industry
."""
:; :j
2
,/
10
1926'30
Figure 2.
(34
I36 '42 Year
'46
'50
-54
Research scientists and engineers employed by industry
of sales for a number of years, this increased production would alone account for much of the increase in research expenditure. Forward estimates of petrochemicals requirements as supplied by the Paley Report ( 2 ) and shown on the same figure give some indication of what research effort will expand t o in the nottoo-distant future. It should be pointed out that the classification "petrochemical" is somewhat arbitrary, and statistics provided are not always consistent but give the order of magnitude, which is what we are concerned with here. KOone in this field need be told that during the period of this expansion, competition has increased materially. T h e few companies, including Shell Chemical, engaged in petrochemical manufacturing in the year 1931 have been joined by many others, until a t the present time there are approximately 140 individual companies operating 300 plants (Figure 5) It might appear that competition has increased out of proportion t o the demand for products in this field. This rivalry has made it necessary for management to establish with certainty that capital expenditures will be made only for processes t h a t are economically superior. This has led to a great increase in the use of process engineering evaluations, necessitating more detailed development and engineering efforts. Sufficient data must be made available for assessment over a range of variables. One must certainly include a comparison with competitors' positions, if at all possible. The rapidly increasing cost of construction also must be considered and every effort made t o design plants requiring a minimum of capital investment consistent with reasonable manufacturing costs. The magnitude of this effect is indicated by the sizable increase in the cost of construction over the past years. Perhaps the most reliable index of construction costs is that provided by the Engineering News Record. The increase in
INDUSTRIAL AND ENGINEERING CHEMISTRY
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ENGINEERING, DESIGN, AND PROCESS DEVELOPMENT their index from 100 in the year 1913 to a value of 622 in June of 1954 is shown in Figure 6. This figure shows that the cost of construction has more than doubled since the beginning of 1946. A study made on the relation between capital outlay and research expenditures in the chemical industry showed that the major chemical companies expend for research a sum equivalent t o 15 to 4501, of funds expended for capital expansion with the average on the order of 3301,. It is obvious that the same forces t h a t increase the costs of construction have more than a linear effect on the cost of doing research. I
I
;.t
o o/
18
6’
1 04 1
/ 6
1926
‘30
I ’34
I ‘38
I ’4L
I ‘46
I 150
I54
Year
Figure 3.
Research expenditure per professional in industry
With this background, showing the influence of rapidly increasing markets, greater competition, and inflationary forces on research and development expenditures, there is a real incentive for research and development management to minimize expense b y utilization of any available knowledge bearing on a specific problem. Among the sources of data available are the chemical Literature, of which the papers in this symposium are examples. If chemical industry would exchange more information through increased publication, duplication of research and development effort could be materially reduced. When one considers the total expenditure in this field of $300,000,000 annually, even a small fraction shared would represent a real saving to everyone. T h e Shell Development Co. has made a considerable contribution to this literature, having published over 400 articles during the past 10 years. Approximately one third of these relate t o chemical products and processes. Disclosures in the patent literature also provide knowledge which can be used effectively. Patents in the chemical field are being issued a t the rate of more than 6000 annually. Shell Development has been granted over 1600 patents over the past 10 years, of which approximately 850 are in the chemical classification. Another source of know-how, discussed in another article in this symposium, is available t o development management in the form of licensing. The Shell Development Co. participates b y licensing processes in both the chemical and refining fields and has made over twenty processes available to industry in the past 10 years. Having research carried out “to order” by independent laboratories is one answer for companies t h a t do not have research departments. It is also often used by companies, both large and small, including our own, when a problem arises that is outside the scope of their own laboratories-when costly equipment not applicable to the company’s usual projects is required or when the employment of extra temporary personnel would be necessary. The most important source of information on which t o base process development, however, is the utilization of one’s own research and development know-how on related processes. This source is obviously available in proportion t o the extent of prior experience in the field involved, whether it applies t o exploratory 984
or bench scale research, pilot plant investigation, process design, or commercial operating experience. As an example of the utilization of know-how available within the Shell Group, and the savings afforded by its use, the new Shell ethyl chloride commercial process development is described. Shell Ethyl Chloride Process
‘
I n the year 1949 the Associated Ethyl Go., Ltd., in which Shell has a part interest, decided t o erect new tetraethyllead facilities a t Ellesmere Port, Cheshire, England. Shell Development was approached for assistance in the choice of a process for the manufacture of ethyl chloride. Although Shell Chemical was manufacturing ethyl chloride via hydrochlorination a t Houston, Tex., and other processes were available, none met the specific requirements of this particular location. The amount of ethyl chloride required necessitated utilization of more ethylene than could be made available using the dry gas from a catalytic cracking plant in the nearby Shell refinery. Although the ethane available in the same stream or propane could be cracked t o produce more than enough additional ethylene, a saving could be effected if such cracking facilities could be avoided. There was, in addition, the problem that chlorine was available but not hydrogen chloride. I n addition t o a cracking plant for additional ethylene, therefore, facilities would have been required t o produce hydrogen chloride from chlorine, and hydrogen as well, since no by-product hydrogen was available. A conventional process for the hydrochlorination of ethylene, therefore, had numerous obvious disadvantages, It was conceivable that Shell’s integrated process in which ethane is first substitutively chlorinated and the resulting hydrogen chloride reacted with the ethylene would provide the desired solution t o their problem. However, the work which led t o the Vaughan and Rust patent ( 3 ) of 1941 consisted only of exploratory research. Furthermore, the availability of hydrogen chlo-
Figure 4.
U. S. petrochemical production (2)
1926’30
I34
138
‘42
‘46
’50
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Year
Figure
5. U. S. petrochemical companies
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KNOW-H 0 W ECONOMICS ride from other chlorination reactions had led to the employment of a n ethylene hydrochlorination reaction a t Houston in 1947, and as a result the projected integrated process of the abovementioned patent had not been developed further. I n fact, the major accomplishment up t o this time had been an understanding of the fundamentals of the reactions involved. This had come about some time earlier when an investigation had been made t o follow up research on high temperature chlorination, first disclosed in the basic patent of Groll, Hearne, Burgin, and LaFrance ( I ) on the chlorination of propylene. The work of Vaughan and Rust led t o the understanding t h a t a t temperatures of the order 400" C. a free radical chain reaction took place, resulting in chlorination of the ethane t o the virtual exclusion of any ethylene present in a mixture: Clz
---f
operating conditions, Reactions 3 and 4 very nearly counterbalance each other, with Reaction 3 predominating slightly. The net result is that, normally, from 1 t o 4% more moles of hydrogen chloride are produced than moles of chlorine fed. Ethylene Hydrochlorination Reaction. This reaction is carried out in t h e vapor phase a t elevated pressure in a reactor packed with catalyst. The main reaction
HCI
(6)
proceeds without any appreciable side reactions. It is a n exothermic reaction, although the heat evolved is less than in the chlorination reaction.
800
2c1
+ CzH4 +CzHsCl
-
+ C ~ He B HC1 + CzH5 CzH5 + Clz C2H5C1+ C1 (chain carrier) C1
--f
A further complication was the desire on the part of the Associated Ethyl Co. t o proceed with construction in one year. The challenge t o take on such a project was accepted with the hope and expectation t h a t the accumulated background of knowledge in all phases of research, development, design, and operation could be brought t o bear to confirm quickly, on a pilot plant scale, that a commercially attractive process did indeed exist, based on the patent of Vaughan and Rust. Before discussing the successful completion of the project and our concept of the time and monetary saving obtained b y the utilization of this know-how, the process involved is described briefly. The process is a combination of substitutive chlorination of ethane and hydrochlorination of ethylene. It is an unusually economical process, because the first reaction produces the hydrogen ch oride required for the second, resulting in complete utilization of the chlorine fed and a high over-all yield of the desired product, ethyl chloride. The chlorination of ethane is a high temperature, vapor phase, noncatalytic reaction. The hydrochlorination of ethylene also is carried out in the vapor phase but at a lower temperature and in the presence of a granular catalyst. The principal variables in these two reactions are as follows: Ethane Chlorination Reaction. The reaction is carried out in the presence of ethylene a t or above 400' C. The over-all reaction is exothermic. The principal product, ethyl chloride, is formed as shown. Clz
+ CzHB --+ CzHsC1 + HC1
(1)
The ethyl chloride can undergo further chlorination C2H5C1
+ Clz
CzHaC12 (1,l-dichloroethane)
+ HCl
(2)
and cracking C*H&l+
CzH4
+ HC1
(3)
Chlorine adds t o the ethylenic double bond as follows: CSHl
+ Cl, --+ CzHdC12 (1,2-&chloroethane)
(4)
There is also a small amount of cracking of the dichloroethanes to vinyl chloride, which also contributes slightly t o HCl production: CzH4C12 ---+CzHaCl
+ HCl
(5)
These reactions are the more important ones, although there are other minor side reactions. Reactions 1 and 2 produce one mole of hydrogen chloride per mole of chlorine fed. Reaction 3 produces hydrogen chloride without directly consuming chlorine, and Reaction 4 consume8 chlorine without producing hydrogen chloride. Under usual May 1955
100 1913'19
125
'31
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'43
'49
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'
7
Year
Figure 6.
Engineering News Record Construction Cost Index (1913 = 100)
An outline of the flow for the ethyl chloride process is given in Figure 7 . Chlorine, ethane, and a recycle gas stream are fed t o the chlorination reactor. The chlorine enters as a vapor. T h e combined ethane and recycle are preheated. The heat given off in the reactor is sufficient t o cause a n adiabatic' temperature rise to the desired reaction temperature. The reactor exit stream is then cooled and sent t o t h e first ethyl chloride column where t h e inerts, unreacted ethane, hydrogen chloride, and some of the ethyl chloride are taken overhead. The rest of the ethyl chloride and other chlorinated by-products leave as bottom product and are sent to crude ethyl chloride storage. T h e overhead stream from this first column plus fresh ethylene is compressed, preheated, and fed t o the hydrochlorination reactor, where from 50 to 80% of the ethylene and the hydrogen chlorine combine. The variation is caused b y declining catalyst activity. I n this reaction, temperature is a more critical variable than it is in chlorination, and the reactor is isothermal with the heat of reaction removed by circulating oil. T h e hydrochlorinator exit stream is cooled and fed to the second ethyl chloride column where crude ethyl chloride is taken out as bottoms and the ethane, inerts, unreacted ethylene, and hydrogen chloride are recycled t o the chlorinator. It is necessary t o vent a portion of this stream t o keep the concentration of inerts from building up. T h e crude ethyl chloride is fed to the ethyl chloride distillation unit, where it is purified in a straightforward manner by passing first through a heavy-ends column and then through a light-ends column. This description covers the essential features of t h e process but there are two or three items worthy of further discussion. First, consider the chlorination reaction. T h e feed t o the reactor consists of chlorine, fresh ethane, and the recycle stream-ethane, hydrogen chloride, ethylene, and inerts. I n the reaction t h e chlorine disappears completely. T h e inerts, of course, remain essentially unchanged. Some of the ethylene reacts, but some ethylene is formed by ethyl chloride cracking. These two reactions usually balance out, and for all practical purposes the moles of ethylene in equal the moles of ethylene out. T h e moles of
INDUSTRIAL AND ENGINEERING CHEMISTRY
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Recycle
ELhare
c-101
3
-1-
L Chlorination Re*CtOl
Figure 7.
F i r s t EC Calurnr
Hydrochlorinstlon Feed Cornprcsrpr
Hydrochlorinatron Reactor
Simplified flow diagram of crude ethyl
hydrogen chloride are increased by a number of moles slightly higher than the number of moles of chlorine fed. I n the hydrochlorination reaction the addition of fresh ethylene to the gas stream from the first ethyl chloride column is automatically controlled so that the ethylene-to-hydrogen chloride ratio in the hydrochlorinator fed is 1: 1. This ratio is not particularly critical, but 1: 1 appears to be optimum. Since this is the ratio in which ethylene and hydrogen chloride react, the ratiosin thereactor exit, recycle, and vent gas streams are also 1: 1. A rather interesting observation can now be made: The fresh ethylene demand for hydrochlorination is set by hydrogen chloride production and, speaking practically, is exactly equal t o hydrogen chloride production. But, as mentioned earlier, its production is very nearly equal t o the chlorine fed, mole per mole. The net result in that the moles of fresh ethylene make-up will be very nearly equal to the moles of chlorine fed, and the ratio of ethylene to chlorine (moles/mole or pound/pound) will be constant. Since both ethylene and ethane are present in the feed streams t o both reactors, it is apparent that it is not necessary for the fresh ethane stream to be pure with respect to ethylene nor for the ethylene stream to be pure with respect to ethane. It is, of course, desirable that the chlorinator feed stream contain a minimum of ethylene, but it is an important advantage of this process that neither the ethane nor the ethylene feed streams need be very highly purified with respect to each other. The ethyl chloride produced in this plant is required for the production of tetraethyllead, which is made by reacting ethyl chloride with a lead sodium alloy. The purity required is very high, and the plant has been designed t o produce finished ethyl chloride suitable for the tetraethyllead reaction. One of the more important problems studied in the pilot plant was the development of a stable control system that would give economical utilization of feed materials. The problem was to admit just the right amount of ethylene to react with hydrogen chloride produced in chlorination, to admit the proper amount of ethane t o keep the ethane-to-chlorine and ethylene-to-ethane ratios steady, and to control the recycle pressure. A completely satisfactory control system was finally achieved. Development of Integrated Ethyl Chloride Process
As soon as ethyl chloride requirements for the projected Associated Ethyl Company’s tetraethyllead plant were established, economic comparison of conventional processes was made with 986
C-102 vent Cas
..
I-
1
Ethylene
-
chloride process. This comparison conclusively established that for conditions at Ellesmere Port, where no hydrogen chloride or hydrogen were available, the Shell process was the most attractive and the decision was reached to proceed with the development of the integrated ethyl chloride process. I n view of the one-year time limit, the development program was initiated in parallel groups. While bench scale research to expand our knowledge of these reactions was being initiated, the pilot plant was being designed and was completed even I before much data became available. Second EC Column It was possible to do this by utilizCrude Ethyl 150 ing know-how accumulated from preChloride StOIape vious development and design work chloride unit on chlorination processes. As bench scale work progressed, an operating program for t h e pilot plant was more exactly defined. Bench scale research progressed for almost 12 months after authorization of the development program. Construction of the pilot plant was completed 4 months from the start of the project. One of the major questions in connection with the operation of a pilot plant was the supply of ethylene and ethane streams for integrated operation. In view of the size of the pilot plant, supply of cylinder ethane and ethylene was out of the question. Manufacture of ethane and ethylene a t the location of the pilot plant would require considerable facilities. Eventually, the problem was solved by leasing Navy helium tank cars and shipping ethane and ethylene of required specification from Shell Chemical’s Houston ethylene plant. Operation of the pilot plant continued for 8 months, and the total pilot plant program from the start of construction to the completion of the project was exactly 12 months. T h e procesz evaluations, as mentioned before, were started before the research authorization and proceeded during construction and operation of the pilot plant. The final process design was completed simultaneously with the completion of pilot plant operation. The process design and the mechanical engineering design were accompanied by a complete set of specifications for all process facilities; these considerably reduced the time required by the contractor t o finalize his plans and begin actual construction. The Associated Ethyl Co. was given, in addition t o the process and mechanical engineering designs, operating, analytical, and basic data manuals. Shell Chemical engineering and operating personnel, experienced in the operation of both chlorination and hydrochlorination units at the Houston plant, were consulted during preparation of the final process and mechanical design. Assistance was provided t o Associated Ethyl and its contractor throughout the construction period. Both Shell Development and Shell Chemical personnel provided assistance during initial stages of plant operation, which began late in 1953. By the earlg part of 1954 the unit had passed its performance test, meeting all requirements both as t o yields, production, and product quality. As this is a large unit, with a capacity of 100 metric tons per day (the largest in Europe) and produces ethyl chloride which must meet the exacting purity requirements for tetraethyllead manufacture, it is believed that the project chosen as an example has been a successful one. Sufficient information regarding this process has been given to enable the reader to estimate the magnitude of such a project if carried out in his own research and development organization. 4
n
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KNOW-HOW ECONOMICS It is the considered judgment of Shell Development management that without the effective utilization of the cumulative know-how of past years, both in research, development, and operation of chlorination and hydrochlorination reactions, a project of this nature could not have been completed for less than $1,500,000. Far more than this amount has been spent in amassing the knowhow utilized. T h e project was actually completed for much less than this amount, including both research and development expense and all phases of engineering. T h e entire project was completed successfully within the desired period of one year, whereas a project of this complexity could normally be expected to require 3 years or more from inception to completion of a design suitable for construction purposes. It has been shown by this example that it is possible to save a major portion of the expense in time and money required to
complete development projects by the use of know-how. In addition, it has been shown how one may license a process with a considerable saving in time and expense and with the additional insurance of assistance from personnel who have both designed and operated identical or related plants. literature Cited (1) Groll, H. P. A , , Hearne, G. W., Eurgin, J., and LaFrance, D.
S., (to Shell Development Co.), U. S.Patent 2,130,084 (1938). (2) “Resources for Freedom,” President’s Materials Policy Comm. (U. S.Govt. Printing Office, Washington 25, D. C.), Vol. IV, 1952. (3) Vaughan, W. E., and Rust, F. F. (to Shell Development Co.), U. S. Patent 2,246,082 (1941). RECEIVED for review dugust 9, 1954.
ACCEPTED February 7, 1955.
Costs in Developing Process Know-How J. S. REARICK
The C. W. Nofsinger Co., Kansas City, Mo. The development of process and engineering data on a pilot plant scale i s an important aspect of “know-how.” Some of the factors affecting equipment and operating cost are defined and discussed. Unit prices for a few commonly used equipment items are given together with an analysis of typical operations.
A
S THE use of continuous processing has become more wide-
spread in the chemical industry, the pilot plant has assumed a position of key importance in process development. The evolution of sound techniques for design and operation has improved the reliability of pilot plant data and increased its utility, both for the evaluation of new processes and for the engineering design of the full scale plants. As processing schemes have become more complex and as operating conditions have become more severe, the acquisition of pilot plant know-how has become increasingly expensive. “Know-how” is a particularly apt term for the practical experience essential to successful pilot plant design and operation. T h e value of such information has long been recognized in the petroleum industry and provision for exchange of pilot plant know-how is included in many licensing agreements. Factors Affecting Development Costs
One of the more important cost factors in developing process know-how is the scope of the program; this involves not only the pilot plant itself, but also such auxiliary work as development of analytical methods, experimental determination of thermodynamic data, or application tests of the final product. I n a catalytic process, it may be necessary to carry on studies t o determine stability and life of the catalyst. T h e scale of the pilot plant work also has an important bearing on process development costs from the standpoint of both investment and operation. T h e pilot plant size will generally be the compromise that most nearly satisfies various requirements ( 3 , 7’). If samples of the product are required for evaluation, the output of the plant should provide the necessary amount in a reasonable length of time. Availability of feed stock or problems of disposal of waste products may act to limit the size of the plant. On the other hand, a given minimum capacity may be necessary t o permit utilization of representative equipment May 1955
of certain types. If the over-all process can be broken down into several separate steps, it may be desirable to carry these out on different scales (4). The degree of integration is also a factor that requires study. Generally, for any particular situation, there is an optimum balance between the increased complexity of the completely integrated operation and the disadvantages of individual processing steps. Operations involving recycle streams must usually be integrated, but frequently it is more economical to separate product finishing or purification operations. The anticipated duration of the program will normally affect the relationship between investment and operating cost, since the longer the period of operation the greater the expenditure that can be justified to reduce operational manpower and expense. If the urgency is great, costs may be considerably larger than if time is available for a more orderly development program. Finally, there are a number of factors which are specific to the particular organization carrying on the work, rather than t o the process itself. These include cost accounting practices, experience in similar work, extent of current activities, labor situation, philosophy of operation, and similar intangibles. Equipment Costs
Occasionally, the only purpose of a pilot plant is to produce large samples of the product for market development or similar purposes. T h e function of such a plant is to provide product rather than process know-how. For the situation under consideration here, however, the extent of the pilot plant facilities and, indeed, even the necessity for a pilot plant a t all, is determined by the area of uncertainty in the design of the full scale plant. A recent study of twelve types of equipment representing seven unit operations indicated that for only three were pilot plant tests considered necessary ( 5 ) , provided certain characteristics of the materials were known. ,4n analysis of a processing
INDUSTRIAL AND ENGINEERING CHEMISTRY
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