ANALYTICAL EDITION
Vol. 5 , No. 5
Ed., 3, 138 (1931).
(34) Wilson, M. M., and Wooster, F. J., IND.ENQ.CHEM.,21, 592 (1929). (35) Young,‘S., “Distillation Principles and Processes,” Macmillan, 1922.
Leipzig, 1928.
RECEIVED May 8, 1933
Robinson, C. S., “Elements of Fractional Distillation,”
McGraw-Hill. 1922. Schwartz, A. M., and Bush, M. T., IND.ENQ.CHEM.,Anal.
Thomann, Kurt, “Destillieren und Rektifizieren,”Otto Spamer,
Method for Determining the Dustiness of Coal and Coke A. R. POWELL AND C. C. RUSSELL,The Koppers Research Corporation, Pittsburgh, Pa.
T
HE treatment of s o l i d bottom slide is 61 cm. above the Dustless coal and coke for domestic fuel have fuels to allay dust a t the bottom and serves to collect the been a subject of iniense interest in the sale of time of delivery, and also d u s t a f t e r t h e fuel has been fuel. The rapid growth of interest and use of dropped. Guides are placed so to prevent dust after the fuel fuel treatment to allay dust led to the introduction that the slides move easily. A dries out in the householder’s of many materials for this purpose. The drawer 30.5 em. deep is located bin, was introduced several years ago. A rapid growth of interest at the bottom of the apparatus, necessity of a quantitative method was soon and provides a convenient means by fuel merchant a n d p r o recognized for the determination of the dustiness of removing the fuel after the ducers ensued, r e s u l t i n g i n a of solid fuels and also for comparison qf the very general adoption of some test is completed. The entire eficacy of the various materials suggested for a p p a r a t u s is made of fairly form of fuel treatment. Calcium treatment. A method and apparatus were heavy sheet metal and so conchloride was one of the materials s t r u c t e d that it is dust-tight. suggested for the purpose, but consequently developed. The top slide is made of sheet a variety of other materials has While the test is empirical and results obsteel and the bottom slide of also been proposed and offered tained with treated fuels must be compared with rather thin sheet polished on one to the trade. Spray manufacblanks of the untreated fuel sampled at the same side-for example, stainless steel turers have also interested themtime, the usefulness has been proved through use or chromium-plated brass. The selves in developing equipment inside surface of the apparatus for the small coal yard as well over a period of years. Data obtained by this is smooth from the top to the as for larger producers and dismethod are presented. lower slide. tributors. The Drinciple of fuel t r e a t METHODOF MAKINGDETERMINATIONS ment i&olvek spraying with a solution or emulsion of some material which has the property of holding dust permanently The top compartment of the box, made by the insertion of the to the individual pieces of fuel, or to agglomerate the dust so upper slide, holds the sample of fuel to be tested. A sample of that it will not rise when the fuel is handled. Calcium chlo- about 25 kg. is placed in this compartment and the cover closed It has been found more satisfactory to weigh the sample ride solutions are used because of the deliquescent properties tightly. as taken rather than try t o obtain exactly 25 kg. The lower of that salt. Other materials, such as oil, modified waste (polished) slide, which has been brushed clean, is then placed in sulfite liquor, emulsions, etc., are also utilized. Any material the guide extension in position for insertion. When ail is in readiness for the test, the up er slide is withdrawn with one quick used for fuel treatment must be both effective and cheap. motion, thus allowing the Fuel t o drop into the drawer. ExThe problem of treating fuel resolves itself into selection actly 6 seconds later, as indicated by a stop watch, the lower of a material which will allay dust, selection of a satisfactory slide is inserted and allowed to stand undisturbed for 2 minutes. method of application, and determination of the quantity of At the end of that time the slide is removed and the dust which has settled on it is carefully brushed into a weighing bottle and material necessary to make the fuel substantially dustless. weighed on an analytical balance. The weight of dust obtained It is evident that some method of quantitative determina- is reported in gram8 per metric ton of fuel. tion of the dustiness of fuel both before and after treatment In addition to the above procedure, it has been found desirable is necessary to make adequate comparisons of the effective- in some cases to determine not only the dust which will settle ness of various materials, quantities of treating agent, and in 2 minutes but also that which will settle in 10 minutes. This is accomplished by the use of two slides at the bottom. Both methods of application. The Koppers Research Corporation slides are inserted together 5 seconds after the fuel is dropped, has developed a method which has been in use since 1928, and 2 minutes later the top one is withdrawn. The second slide and, although it is empirical, it is believed that the results is withdrawn 8 minutes later. The ratio of the two values gives a size-characteristic of the dust and is important in determining obtained are satisfactory. the efficacy of various treatments. DESCRIPTION OF APPARATUS The dust tests should be made in a room free of strong The method involves dropping a weighed quantity of fuel drafts, so that no dust will be blown out of the sample or into a closed container and allowing the dust so raised to apparatus, and so that the settled dust can be transferred to settle on a polished metal plate so that it can be removed the weighing bottle without loss. and weighed. The apparatus consists of a box 1.52 meters SAMPLING high and 45.7 em. square, arranged with a cover and having In sampling fuel for the dust test, extreme care must be two horizontal slides inserted from the side. The top slide is 30.5 cm. below the top and, when inserted, makes a com- taken so that the normal amount of dust will be retained. It is obvious that the fuel can be tested as sampled with the partment in which the fuel to be tested is placed. The
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September 15, 1933
INDUSTRIAL AKD ENGINEERING CHEMISTRY
original moisture content or it can be tested after drying to remove moisture which would evaporate under storage conditions. I n either case it is desirable to have a moisture determination a t the time of the test. If the dustiness as sampled is to be determined, the test must be made immediately after sampling or else the sample should be stored in a moisture-proof container and tested as soon as practicable.
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standard amount of calcium chloride-e. g., 2 kg. per metric ton, in the case of coke. The report of results on each dust test should include: 1. Description of fuel: source, size, point of sampling, etc. 2. Moist,ure content before spraying, when samples are obtained at point of treatment. 3. Material used to lay dust. 4. Weight of dust-laying agent and total volume of material or
solution applied.
5. Length of time of storage. 6. Average temperature conditions during storage.
7. Average humidity conditions during storage.
Temperature and relative humidity at time of test. Moisture content of fuel at time of test. 10. Amount of dust in grams per metric ton. 8. 9.
AGREEMENT OF RESULTS In Table I are shown the results of duplicate and triplicate determinations made on different solid fuels, with and without treatment with a dust-laying agent. The usual dust-settling period is 2 minutes, but a few determinations with a period of 10 minutes are shown for comparison. TABLEI. AGREEMENT OF TESTS UNTREATED FUEL Coke A Coke B Coke C Cake D Coal A T R ~ A T EFUEL D Cake A Cake B Cake C Coke D Coal A
FIGURE1. GENERAL VIEW OF APPARATUS However, if it is desired to determine the dustiness which may develop when fuel is stored under dry conditions, such as in a householder's basement, the sample is dried under controlled conditions as described below. DRYINGPROCEDURE In order to determine the effectiveness of any dust-laying treatment for fuel, it is necessary to dry the sample under controlled storage conditions approximating very dry air conditions in the householder's basement. While an elaborate system of drying under controlled humidity conditions may be used, the following procedure is simple and gives satisfactory results: Each 25-kg. sample is placed in a flat-bottomed container of not less than 61 cm. diameter. Large galvanized washtubs are satisfactory. The samples are exposed t o the air for 10 days in a room whose temperature is maintained at 15' C. higher than the average outside temperature. The windows should be open but covered with muslin t o keep out the dust and permit the higher temperature to be maintained in the room. It is desirable t o obtain the relative humidity of the air in the room several times during the storage period and also at the time of the duet test. When making comparisons of the effectiveness of various materials for dust-laying, samples of untreated fuel must also be included in each series of tests for comparison. It may be desirable also t o include a sample treated with a Y
6
DUST-SETTLINQ GRAMS OF DUSTPER METRIC TON PERIOD Test 1 Test 2 Test3 Min. 2 133 140 2 131 157 2 105 124 140 131 138 1; 151 139 146 2 134 106 130
.... .. ...
{
2 2 2
j1; 2
A rather interesting point is brought out by the results obtained from Coke D. The untreated coke shows an appreciable settling of dust beyond the 2-minute period. However, this same coke after treatment shows almost negligible dust beyond the 2-minute period, indicating that treatment has decreased the more objectionable fine dust to a much greater extent than the 2-minute figures indicate for the coarser and less objectionable dust. Table I1 shows some data in regard to the effectiveness of various treating agents on coke, together with the amount required t o give the result obtained. OF VARIOUSTREATING AGENTS ON TABLE11. EFFECTIVENESS COKE
TREATING BGENT A A A B
c
D E Untreated cake (dried)
QUANTITY OF DUSTI N TREATED TREATINQ AGENT COKE(DRIED) Kg./melric Zon Crams/metric ton 0.70 10 0.45 20 0.35 29 0.90 42 1.75 21 80 1.20 1.45 50 149
..
These samples were dried as described before testing. This method has been used to determine the efficacy of treatment of various dust-laying agents, and upon that basis decisions have been made in the selection of the most satisfactory materials. RECEIVED June 27, 1933. Presented before the Division of Gas and Fuel Chemistry at ther85th Meeting of the American Chemical Society, Washington, D. C., March 26 t o 31, 1933.
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