Municipal Incineration of Refuse with 2 Percent and 4 Percent

Additions of Four Plastics: Polyethylene, Polyurethane,

Polystyrene and Polyvinyl Chloride

ELMER R. KAISER and ARRIGO A. CAROTTI New York University

Bronx, New York

ABSTRACT

Tests were conducted in a municipal incinerator with four plastics added to normal refuse in amounts equal to 2 and 4 percent of the base refuse. The plastics burned without smoke or dripping through the grate. P lastics improved combustion and helped to burn wet refuse. The emissions of noxious gases due to plastics were minor, except that hydrogen chloride increased when chlorinated plastics were added. A gas scrubber reduced the chloride content of the flue gas.

INTRODUCTION

Plastics are synthetic materials, usually petroleum based. The major constituents of plastics are carbon and hydrogen, although some also contain nitrogen and oxygen as basic ingredients. Included in the 1 2 broad categories of plastics families is vinyl, a group of chlori­nated hydrocarbons composing 20 percent of the pro­duction.

The U.S. production of plastics materials (resins) dur­ing 1970 has been estimated by The Society of the Plas­tics Industry at 9.35 million tons, an increase of 2 per­cent above the 1969 total.

Like other materials, plastics enter the national waste stream at several points from manufacture to final con­sumer use. Solid waste from households and small com­merical establishments in the eastern urban areas cur­rently contains 2-3 percent of film, bottles , and other shapes produced from a variety of different plastics

formulations. Niessen and Chansky [1] reported 1.4 percent as a national average. Industrial wastes fluctu­ate widely as to their content of plastics, but over-all, it is reasonable to assume that plastics constitute 2 per­cent of municipal refuse .

Questions have been raised relative to the future role of plastics in incinerators, particularly as the amount of plastics mixed in with other refuse being burned in­creases. Will the plastics melt and clog the grates or drip through the grate openings, carrying fire into the ash pits or wind-boxes? Will the higher calorific value of plastics cause excessive incinerator temperatures and furnace damage? Will plastics increase the air pollution from incinerators?

On the positive side, other questions have also been asked: Will the presence of plastics in refuse aid in the combustion of wet refuse? Will the higher calorific value of plastics facilitate the use of the incineration process to generate steam and power? What improvements in incinerator design and operation can be effected to ben­efit the incineration of plastics?

As the test data will show, plastics provided heat units that assisted in the burning of wet refuse . Plastics are largely hydrocarbons with calorific values several times higher than that of normal refuse. Since they burn readily at incinerator temperatures when mixed with household and commerical refuse, and do not drip through the grates, the extra heat would be useful for steam generation . The use of gas scrubbers of corrosion­proof design would remove particulate matter from the flue gas and also remove most of the acid gas produced by vinyl plastics.

230

OBJECTIVES AND SCOPE OF INVESTIGATION

Recognizing the importance of the subject and the questions being raised, The Society of the Plastics In­dustry, guided by its Solid Waste Management Com­mittee, proposed a series of tests on a typical full-scale, municipal incinerator. Test procedure involved the ad­dition to the normal refuse of selected quantities of major plastics materials equal to 2 and 4 percent of the refuse weight. This procedure, in effect, doubled or tripled the amount of plastics materials currently found in such refuse. Thus, assuming present trends, changes in incinerator performance could be forecast for the years in the future (i.e., 19 80-1990) when plastics con­sumption and discard may be at two or three times present levels. Whether recycling of wastes will change this prediction remains to be seen.

Four types of plastics were selected for the tests: Polyethylene, polystyrene, polyurethane, and polyvinyl chloride. Seven thousand pounds of each plastic, in the form of film, sheet, bottles, foam, and manufacturing scrap, were supplied by a number of plastics processors.

Through the cooperation of town officials, the in­cinerator plant of the Town of Babylon, N. Y., was made available for the tests. It was recognized that a working incinerator plant and the daily refuse receipts could not be controlled to the degree possible with a small in­cinerator in a laboratory. Also, the tests would be limited to one type of incinerator furnace: an all-refrac­tory, continuous-feed unit with oscillating or rocking grate. But the importance of using a large-Size typical working facility and achieving realistic results under norm-a! working conditions was deemed paramount.

This paper is an abbreviated report of the investiga­tion. A complete report is available from The Society of the Plastics Industry, 250 Park Avenue, New York, N. Y. 10017.

INCINERATOR PLANT

The incinerator plant consisted of two identical fur­naces, each rated at 200 tons/ 24-h ( 8.33 tons/h of refuse). Each furnace was 8 ft wide inside and had four independently controlled grate sections or zones each 9 ft 4 in. long. The fire-active, horizontally-projected grate area was 27 2 ft2. Hence, the average rated burn­ing rate was 61.3 Ib/ft2 -h. The furnaces normally op­erated three shifts a day, at about 90-95 percent of rating, with shutdowns on weekends for lack of refuse.

As shown in Figs. I a and I b, each furnace was re­fractory lined and had continuous feeding of refuse from a chute that was kept filled by a crane and grapple. The refuse was moved progressively down the sloping

231

Flynn and Emrich stoker grate by the rocking action of grate castings, powered by hydraulic cylinders and crank arms. The grates had slotted openings 3/4 x 6 in., comprising 20 percent of the total grate area. The rate of refuse movement on the grate was controlled by an automatic timer which actuated the hydraulic cylinders in accordance with a preset schedule.

Air was supplied under the two central grate zones of each furnace by a centrifugal blower. No underfire air was supplied to the first (feeding) zone, while furnace room air was induced to the fourth zone by natural draft.

Forced air was also supplied over the fire bed by numerous nozzles in the sidewalls to promote burnout of gases, vapors and particulate matter evolved from the refuse bed. The total air supplied was 200 to 300 per­cent of stoichiometric requirements for controlling the furnace temperature.

Ash, glass, small metal, and a minor amount of com­bustible sifted through the grate openings, fell through the windboxes, down 1 2-in. pipes, and into a wet conveyor. Most of the residue dropped off the end of the grate into a hopper, where it was spray quenched and discharged periodically for removal by truck. Siftings and grate residue were hauled to a nearby sanitary landfill.

Furnace temperature was measured continually by a thermocouple in the furnace roof (arch) which was con­nected to a controller-recorder on the panel board. The controller was set for 1700 F during the tests. The tem­perature was prevented from exceeding 1700 F longer than short periods by increasing the amount of over­fire air. Buoyancy caused the hottest furnace gases to flow along the top of the furnace to the flue exit, while cooler gases left the furnace at lower levels in the flue. Turbulence in the flue produced a gas mixture at the point of sampling with a temperature usually in the 1000-1300 F range.

The flue gases from the two furnaces converged and dropped into a lower passage, where they were sprayed with water to knock down the larger particles of fly ash and to cool the gases to roughly 600 F. The fly ash was sluiced out to a treatment plant. A gas cleaning system of higher efficiency is currently under consideration.

Natural draft for the furnaces is provided by a 1 26-ft brick chimney of 1 2.5 ft inside diameter. The stack gases are normally barely visible in warm weather, in­creasing in density due to vapor fog produced during cold weather when the gases mix with the winter atmos­phere.

These furnaces represent the best of typical modern U.S. design, and are similar in most respects to other in­cinerators built during the last decade. The furnaces were updated in several respects in the Spring of 1970. Incinerator plants built recently or now in the planning

UFUSE PIT

-..rm-IT-·I . �

I I I

I I

TOWN OF BABYLON, N.Y., INCINERATOR

2 FURNACES - 200 TONS/DAY EACH

Scal. 0""; 10 Ib 2'0

FURNACE

Fig. 1a Cross-section of furnaces and flues.

F"t

" II I, II

TOWN OF BABYLON, N.Y, INCINERATOR

>< tl---4.'I SECTION 8-8 (," "� III io

)

FlII'n No I Furn.Ho 2

"

n

�sproy NOli'" /

SETTLING CHAMaER >--. ', ' i;

Fig. 1 b Cross-section of test furnaces and plant.

23 2

"

stage will have gas scrubbers or electrostatic precipitators for removal of dust from the flue gases.

PLAN OF TESTS

The plant was available for test purposes on condition that the normal operation would not be interrupted. This was agreed and all experimental work was carried out during normal operating conditions.

The initial plan was to conduct a series of three tests on successive days with the same furnace. No plastics would be added the first day, 2 percent plastics added the second day, and 4 percent plastics the third day. Data would be taken during six hours of "steady-state" operation each day during daylight hours. The furnace was to be "conditioned" on the second and third days by adding plastic to the normal refuse feed an hour before beginning the test run.

The above plan was followed for the tests on poly­ethylene, polystyrene and polyurethane. As these plas­tics contained little or no chlorine or sulfur, day-to-day variations in the normal refuse feed were not deemed sufficient during three days of the same week to affect the comparative results sought. However, difference in chloride emissions in the earlier tests were substantial. Hence, when the tests on polyvinyl chloride were or­ganized, one furnace was operated without PVC addi­tions while the other was charged with the same base refuse plus PVC. It was felt that alternate grapple loads from the pit to each incinerator, approximately 50 to each furnace, would reduce differences in the chlorine content to each furnace to a negligible level.

The sponsors understood the limitations of testing on full-scale furnaces as compared to laboratory fur­naces in which the refuse composition and air rates could be kept constant. Variations in results of the control runs were expected. Plastics in all tests were a minor part of the refuse, but the techniques used would discern important effects and their general magnitude.

Dates of tests series:

Polyethylene Polystyrene Polyurethane Polyvinyl chloride

[

July 27-29,1970 Sept. 8-10,1970 Sept. 28-30, 1970 Nov. 17-18, 1970

INSTRUMENTATION

Use was made of the gauges, recorders and controls of the Babylon plant which included:

(1) Strip chart potentiometer with Cr-AI thermo­couple in furnace arch;

(2) Gauges for furnace and chimney draft and pres­sure of supply air, underfire and over fire; and

(3) Sequence timer and automatic control of stoker strokes.

Instrumentation installed by NYU included: (1) Water-jacketed sampling probe for flue gas samp­

ling. Probe projected into the center of the hot flue and contained four glass sampling tubes of 12 mm bore. One probe per furnace.

(2) Continuous sampling train to collect representa­tive sample of flue gas for Orsat analysis.

(3) Continuous sampling train for collection of flue gas for NOx, CC, CN-, S02, organic acids, aldehydes, phosgene, etc., analysis.

233

(4) Continuous sampling of flue gas for miniature scrubber train, including impinger bottles in constant temperature water bath, integrating gas meter, thermom­eter, vacuum gauges, condenser in ice water, catch bottles, etc., as shown in Fig. 2.

(5) Sampling for odor of stack gas. Analysis of ASTM syringe technique for threshold of perception.

(6) Photoelectric smoke meter with direct aspiration of flue gas four times an hour.

The temperature near the sampling point in the hot flue was measured at 20-min. intervals by portable po­tentiometer and Cr-AI thermocouple. This temperature represented the true gas temperature while the arch thermocouple was influenced by flame radiation, con­vection, and radiation to colder parts of the furnace.

Miniature Scrubber

Though not a normal part of the Babylon incinerator, a miniature scrubber was used for testing in this project. This activity was initiated out of awareness that gas scrubbers are currently being installed on a number of U.S. municipal and on-site incinerators. They are effec­tive and economical for removing particulate matter from flue gas. They are also known to capture HCI, which is one of several causes of corrosion of carbon and stainless steels used in scrubber construction.

A continuous steady stream of flue gas from the probe was passed through two Greenburg-Smith im­pingers in parallel. The impingers were submerged in a water bath maintained at 175-180 F. Scrubbers normally operate adiabatically at about 170 F. The pressure drop through the impingers was 1.2 in. of mercury to obtain a flow of 0.75 cfm through both units, as well as intimate contact of small gas bubbles with the water in the im­pinger. Flue dust and moisture condensed by the probe were drained into the impingers. Distilled water was added to the impingers to make up evaporative losses and to provide overflow of impinger water, thus simu­lating run-off water from the scrubber.

The miniature scrubber was followed by a glass tubu­lar condenser in ice water to condense moisture and to

GAS SAMPLER AND ORSAT

B AIR BLEED MW MAKE-UP WATER

C CONDENSATE OF IMPINGER OVERFLOW

F GLASS WOOL FILTER

GM GAS METER

H HEATER

I IMPINGER

IB ICE BATK

M He MANOMETER

R ROTAMETERS

S STIRRER

T THERMOMETER

V VACUUM GAGE

VP VACUUM PUMP

WB WATER BATH

C

GAS SCRUBBER TRAIN

Fig. 2 Flue·gas sampling trains and scrubber.

thereby trap HCl that escaped the scrubber. The result­ant gas was measured by a dry gas meter. After measur­ing the impinger water and the condensate, samples of both were analyzed for chlorine content.

ANALYTICAL METHODS

Nitric Oxide, NO

Subcommittee 3, B. E. Saltzman, et a1. "Tentative Method of Analysis for Nitrogen Dioxide Content of the Atmosphere (Griess-Saltzman Reaction)," Inter­society Committee, first edition, Manual of Methods of Ambient Air Sampling and Analysis, vol. 6, no. 2, H.L.S., 106-113, April 1969. Evacuated Bottle Method for concentrations up to 100 ppm. This is a version of the ASTM Method D 1607, adopted 1960 and revised 1969. Adapted from "Selected Methods for the Measure­ment of Air Pollutants," PHS Publication No. 999-AP- ll, May 1965.

Nitric oxide, NO, was converted to an equivalent amount of nitrogen dioxide, N02, by passage through a bubbler containing acid permanganate. The N02 was absorbed in an azo dye-forming reagent. A stable pink color is produced within 15 minutes which may be read visually or in an appropriate instrument at 500 mJ..L.

Chlorides, CI

Acid gases and mists were trapped in 1.5 N aq. NaOH contained in a Greenburg-Smith impinger. The

234

impinger content was maintained at O°C to improve gas solubility and to minimize water vapor transport to downstream rotameters. In each case, the liquid col­lected in the O°C trap immediately following the probe, Fig. 2, was combined with the alkaline collection media.

The chloride concentration was conventionally quan­titated volumetrically via Volhard titration and potenti­ometrically using the silver electrode.

Cyanide, CN

Hydrogen cyanide was quantitatively collected as an acid gas and/or mist (see Chloride, Cr: above).

The CN- concentration was quantitated spectrophoto­metrically using the method of V. Kratocheil, "Collection of Czech. Chern. Communications," vol. 25, p. 299 (1960); (Ana/. Abstrcs., vol. 7, no. 3679, "The Use of Dimedone in the Photometric Detmn. of CN-".

CN- is quantitatively converted to cyanogen chloride with chloramine T. Cyanogen chloride reacts with pyridene to form glutacon aldehyde. The latter forms a violet-colored complex with dimedone which absorbs in the region of 5 80-5 85 mu. The method is specific for CN- and extremely sensitive.

Fluoride, F-

Hydrogen fluoride and other volatile inorganic fluorides were quantitatively collected as described under chloride, Cl- above.

The F- concentration was quantitated spectrophoto­metrically using the method of R. Greenhalgh and J. P. Riley, Anal. Chirn. Acta, vol. 25, p. 179 (1961).

In an aqueous solution of pH 4.5, F- forms a colored complex, with lanthanum-aHzarin-complexone, which absorbes in the region of 622 mJ.1. The method is spe­cific and extremely sensitive.

-Phosphate, P04 =

Volatile phosphorous compounds (e.g. phosphorous acids, oxides and halides) were quantitatively collected as described under Chloride, Cl-, above.

The P04 == concentration was conventionally quanti­tated gravimetrically via the phosphomolybdate.

Organic Acids as CH3 COOH

Volatile organic acids were quantitatively collected as described under Chloride, Cl-, above.

Following acidification with sulfuric acid, the organic acids were recovered via steam distillation. The distillate, which was free of Cl-, S04 =, and N03 - was concen­trated and then titrated with standard base. The results were reported as acetic acid.

Aldehydes (and ketones) as CH2 0

Aldehydes and ketones were quantitatively absorbed in I percent aq. sodium bisulfite, NaHS03 , contained in a midget impinger in a O°C bath. The total concentra-

I tion of -CHO + � = 0 was in each case quantitated via the method of F. H. Goldman and H. Yagoda of the Division of Industrial Hygiene, National Institute of Health, Bethesda, Md., Industrial and Eng. Chern.,

vol. 15, no. 6, pp. 37i37 8 (1943). After excess, unreacted bisulfite is destroyed with

0.1 and 0.01 N12 solutions, the bisulfite-aldehyde and the bisulfite-ketone addition compounds are dissociated in mild alkaline solution. The liberated bisulfite is then quantitatively titrated with standard iodine solution of predetermined concentration using starch as an indicator. The results are reported as formaldehyde, CH20.

Sulfur Dioxide, S02

Sulfur dioxide was quantitatively collected and oxi­dized in two Greenburg-Smith impingers connected in series, each containing dilute hydrogen peroxide at pHS.

The combined liquid content was in each case volu­metrically analyzed quantitatively for sulfate ..

235

Phosgene, COCI2

Samples were taken directly from the probe into an evacuated, 16.2-liter, stainless steel tank over a period of 6 h.

Small aliquots from the 16.2-liter sample were initial­ly quantitated using Kitigawa gas detection tubes spe­cific for COCl2 (limit of sensitivity = 0.5 ppm).

Phosgene is also quantitated gas chromatographically, following concentration (of the remaining sample) at -IIOC, using a 6 ft x 1/4 in. n-hexadecane coated on a chromosorb, (R), column at 30C isothermal, in con­junction with a thermal conductivity detector .

Chlorine, CI2

The element was quantitatively collected together with other acid gases in the impinger containing aqueous alkali (see Chloride, Cl-: above). After each test about 50 ml of the resulting impinger solution, still alkaline, was packed in ice (O°C) and analyzed a few hours later on arrival at the laboratory.

The hypochlorite concentration of each sample was quantitatively determined spectrophotometically via oxidation of [- to [2 in alkaline solution in the presence of starch (sensitivity limit = 0.2 ppm).

Fly Ash

Samples of fly ash were manually removed from the f100r of the hot fl ue below the first down comer. I n each case, the entire sample was thoroughly mixed. An aliquot portion of each was then ground, mixed again and ex­tracted with distilled water. The water soluble extract was quantitatively analyzed for Cl- via the method de­scribed above. A second portion was also ground, mixed, fused with f1ux and the reSUlting mixture analyzed for P04== via the method described above.

PLAST ICS AND MUN ICIPAL REFUSE

Seven thousand pounds of each of the four types of plastics were delivered to the Babylon Incinerator by truck from processors in nearby states. The materials of each type were received successively as needed. To expedite weighing and handling of the large volume of plastics during each test, the plastics were reloaded at the incinerator into plastic bags of 7 ft3 capacity. As well as possible, each bag received an assortment of each type of bottle, film, sheet, or scrap in the propor-

tion supplied. The loaded bags were stored on the charg­ing floor for accessibility during testing.

The charging procedure during the test was conducted by three or four men. After each grapple load (about 2000 lb) of normal refuse was charged to the test furnace hopper, a weighed quantity of the plastic was distributed over the top of the load by emptying the bags. Forty pounds were required for each load during the 2 percent test, and 80 lb -during the 4 percent test. Partial mixing of plastics and refuse was supplemented by additional stirring by the action of the grates.

Polyethylene

Polyethylene was in the form of film and seven types of new bottles, ranging from one pint to one gallon. A small quantity was in the form of molding machine scrap, which was cut into pieces not exceeding 1 lb each. In preparation for testing and to expedite handling and charging, plastic bags of 7 ft3 capacity were each filled with an assortment of the bottles and film. Rolls of film were slit axially, producing sheets, that were bagged as pads of not over one-half inch thickness, mixed with bottles.

Polystyrene

Polystyrene was received as bales of white foamed sheet, yellow foam trimmings from tray production, and some stiff sheet scrap. Mainly by hand tearing and manual manipulation, the material was broken down into pieces seldom exceeding 10 in. in width and 20 in. in length.

Polyurethane

Polyurethane foam weighing 2 Ib/ft3 was received in the form of slabs of several colors 20 in. thick by 4 ft wide and up to 1 2 ft in length. It was chain sawed into blocks ranging from one fourth to I ft3 . Bagging was not necessary for ease of charging into the hopper.

Polyvinyl Chloride

Five types of PVC bottles, from 6 to 24 tl oz capacity, PVC film, sheet, and heavy molding scrap were received from processors. Reloading into plastic bags was done to facilitate weighing and charging.

Analyses of Plastics

Representative samples of each plastic were taken and chopped in a Wiley Mill to pass 2 mm round open­ings. The samples were analyzed by ASTM methods

236

D- 271-6 8 and D- 2361-66 by a commercial laboratory, which also determined the calorific values. The analyses were calculated to a single, typical moisture content for comparative purposes, as reported in Table 1.

It should be pointed out that the analyses represent commercial products rather than pure polymers. Since plastics are generally compounded before use into formulations that include the base polymer plus pig­ments, plasticizers, stabilizers and other agents, it was decided to work with the actual products that might show up in municipal refuse.

Proximate analyses of the plastics were also con­ducted at the same laboratory by the ASME method D 271-6 8. The volatile matter is the weight loss by rapid destructive distillation in the absence of air. The fixed carbon is the combustible portion of the char re­maining after the volatile matter has been released. See Table 2 for the data.

The data show that polyethylene is most highly volatile and polyvinyl chloride least volatile. Fixed carbon is burned on the grate by exposure to air and high temperature. The volatile matter is burned in the furnace space above the point of origin.

Table 1

Ultimate Analysis, Wt %

Polyethylene Polystyrene Polyurethane

Moisture 0.20 0.20 0.20

Carbon 84.38 86.94 63. 14

Hydrogen 14.14 8.42 6.25

Oxygen 0.00 3.96 17.6 1

Nitrogen 0.06 0.2 1 5.98

Sulfur 0.03 0.02 0.02

Chlorine tr tr 2.42

Ash 1. 19 0.45 4.38

100.00 100_00 100.00

Higher heating value, Btu/lb

Moisture

Volatile matter

fixed carbon

Ash

19,687 16,419 1 1,203

Table 2 Proximate Analyses of Test Plastics, Wt %

Polyethylene Polystyrene Polyurethane

0.20 0.20 0.20

98.54 98.67 87. 12

0.07 0.68 8.30

1. 19 0.45 4.38

100.00 100.00 100.00

Polyvinyl

Chloride

0.20

45.04

5.60

1.56

0.08

0. 14

45.32

2.06

100.00

9,754

Polyvinyl

Chloride

0.20

86.89

10.85

2.06

100.00

Table 3

Semi-Quantitative Spectrographic Analyses of

Mineral Matter in Test Plastics

Polyvinyl

Percentage Polyethylene Polystyrene Polyurethane Chloride

1.00 to 10.00 Phosphorus

0.10 to 1.00 Ti tanium Titanium

0.01 to 0.10 Aluminum Silicon, Silicon Lead, Tin, Phosphorus, Silicon,

Aluminum, Titanium

0.001 to 0.01 Silicon, I ron, I ron, Cadmium, Magnesium , Iron,

Iron, Lead, C hromium, Magnesium, Magnesium, Magnesium Aluminum, Cal- Lead, Tin Chromium,

Lead cium, Cadmium, Calcium Cobalt

0.0001 to Tin, C h romium , Tin, Nickel, Boron, Nickel 0.001 Nickel, Molybdenum, N ickel, Vanadium

Molybdenum, C opper Copper, C opper C obal t , Silver Calcium, Vanadium, C opper

Table 4 The inorganic mineral matter in the plastics was sub­jected to semi-quantitative spectrographic analysis to determine whether any unusual or highly toxic elements were present. The findings are given in Table 3. These same elements are found in normal, non-plastic, refuse.

Physical Composition of Typical Municipal Refuse, %

Refuse

Household refuse predominated, but minor quanti­ties of commercial and industrial waste were also deliv­ered to the incinerator from the surrounding area. The refuse was not sampled during the project, itself a major undertaking. From extensive prior experience in a simi­lar Long Island Community (Oceanside), a reasonable judgmcnt of the refuse could be madc. For example, during the polyethylene and polystyrene tests, late July and early September, minor amounts of lawn clippings (grass) were present, but not during the polyurethane and PVC tests of late September and mid-November. The moisture content of the incoming refuse varied with weather conditions despite the use of closed gar­bage cans and trucks. However, when the refuse was dusty during unloading, or dry loads of commercial and industrial waste were received at the pit, water was sprayed on the refuse in controlled amounts.

Municipal refuse is a heterogeneous mixture that can be sampled and hand sorted into relatively homoge­neous components. After determining the chemical analyses and calorific values of the components, the

Currugated boxboard 6 Textiles 3

Newspaper 13 Wood 3

Magazine, books 2 Food was te 10

All other paper 26 Grass, leaves 5

Plastic shapes 2 Dirt, under I in. 6

Plas tic f ilm Glass, ceramics, s tones 12

Metal -1Q 100

Table 5

Chemical Analysis of a Typical Municipal Refuse, %

237

Moisture 25.00

Carbon

Hydrogen

Oxygen

Nitrogen

Sulfur

25.54

3.34

22.00

0.52

(l.10

Chlorine 0.50

"Inerts"* 23.00

100.00

* G lass, metal, ash.

Btu/lb of ref use (higher val ue): 4577 for o rganic matter only. 150 Btu/lb additional he<lt Illay be released f rom the pa rti<ll oxi­dation of me tals.

composite analysis and calorific value are readily cal­culated. One test was conducted to establish the plas­tics content.

The physical composition of the normal refuse re­ceived at the Babylon incinerator is approximately as given in Table 4, with variations as explained above.

Table 6

General Combustion Performance During

Polyethylene Series

Test No. A·1 A·2

PE added, % of refuse None 2%

Refuse, Ib/h 15,660 14 ,667 Polyethylene, Iblh 0 293

Total, lb/h 15,660 14,960

Furnace arch, F 1689 1687 Flue gas, F 13 15 1160 Flue gas analysis

(O rsat), dry vol. %

CO2 6.48 5.2 CO 0.0 0.0 O2 13.81 15.2

N2 79.71 79.6 Burnout f rom end of g rate, ft 8.13 8.93

Smoke, Ringelmann 0.014 0. 10 O do r Uni ts of fl ue gas 2.0 J.5

Table 7

Concentrations of Noxious Chemical Species in the

A·3

4%

14,333

573

14,906

1709

1200

5.7

0.0

14.2

80. 1

12. 1

0.03

1.0

Flue Gases During the Polyethylene Series, in ppm by

Volume of Dry Gas, Actual and Corrected to 12% CO2

Test No. A-1 A-2

PE added None 2%

C 1-, actual* 217 126

co rrected 402 291

F-, act ual 2.6 3.5

corrected 3.8 8.1

C'N-, actual <0.02 <0.01

corrected <0.04 <0.02

NO, act ual 28.6 40.1

co rrected 53.0 92.7

P04= 0.54 0.54

corrected 1.00 1.25

S02. actual 31.7 35.4

corrected 58.7 8 1.6

Organic acids,

as C H3C O O H, act ual 58.3 17.1

corrected 108 39.4

Aldehydes, as HC' HO, actual 1.5 1.7

corrected 2.8 3.9

* Avenlge of scrubber and NaO H/impinge r methods.

Tests we re not run for phosgene and free chlorine, as the polyethylene contained no chlorine.

A-3

4%

201

424

5.7

10.5

<0.01

< 0.02

39.9

84.0

0.45

0.95

33.2

70.3

5.5 I 1.6

1.2

2.5

23 8

The performance of an incinerator is highly depend­ent on the chemical analysis of the refuse. For the pur­pose of this project the analysis given in Table 5 was assumed for the base refuse. The analysis is based on samples taken on Long Island at Oceanside.

In a recent investigation [ 2] of the chlorine contents of refuse components, all organic fractions were found to contain some chlorine, probably largely as common salt (NaCt). Less than half of the chlorine was present in chlorinated plastics.

TEST FIND INGS

The test results are reported in this section by each of the major plastics involved. The series of test runs for each plastic included one or two blank or control runs with normal refuse and one run each with 2 per­cent and 4 percent plastic addition.

The mechanical stokers of both furnaces operated at the same constant rate of grate action for each test, but the tonnage moved per unit of time varied within limits because of normal fluctuations in refuse compo­sition. Based on the long-term experience of the plant and the weighing of two grapple loads, the average grapple load weight was assumed to be 2000 lb.

Polyethylene (PE)

Three tests were run in Furnace No. I on three suc­cessive days with general results as given in Table 6. The additional polyethylene caused no significant difference in the normally low smoke density. Combustion was actually improved by adding this plastic, as shown by a lower odor concentration in the flue gas and by a short­ening of the active fuel bed. Burnout occurred at a greater distance from the end of the grate when more polyethylene was added. The further the burnout from the end of the grate, the more rapid and complete the burnout. Thus, this distance in feet is a convenient and quantitat ive index of rate of burnout. No evidence of melted polyethylene was found in the grate siftings and no clogging of grates was reported.

Table 7 presents the concentrations of chemical species in the flue gases. In general, the noxious gases were present in very low amounts.

Probably most significant of the data in Table 7 is the decrease in organic acids in the flue gas because of the better combustion resulting from the increased poly­ethylene in the refuse. The variation in chloride, fluoride, and phosphate ions, and in sulfur dioxide, reflect the normal variations in refuse analysis.

Chlorides were captured by the miniature flue gas scrubber and condensation train. The scrubber efficiency was over 80 percent, showing the effectiveness of water

scrubbers in removing chlorides from flue gas. The con­cen tra tions of chlorides were comparable to those re­ported in Table 7.

The scrubber impinger and overflow water had a final pH of 1.2-2.0 while the condensate had pH 3.0. Also significant, the chlorides were over 90 percent He!.

The amount of nitric oxide produced was higher dur­ing the tests with polyethylene than during the control tests, possibly because of sligh tly higher fuel bed tem­peratures due to the high calorific value of the plastic. It is not clear why the amount of NO during Test A-2 was not intermediate between that of Tests A-I and A-3.

Polystyrene (PS)

Three tests were run in Furnace No.1 on successive days, with general results as given in Table 8. The ad­ditional polystyrene burned clean; no smoke was de­tected by meter or by inspection of the stack discharge. Witltin the limits of measurement, less odor was de­tected in the flue gas when PS was added to the refuse.

Burnout occurred rapidly, well short of the end of the grate in all runs of the series. The low ash content of the plastic and a calorific value over three times that of normal refuse would favor PS additions during the burning of wet refuse. Because of the high heat release from the plastic, more excess air was added to the fur­nace to control the furnace arch temperature, a normal opera ting proced ure.

No melted plastic was found in the grate siftings and no clogging of grates by plastics was noted by the opera­tors.

The concentrations of noxious species in the flue gas are listed in Table 9.

239

Table 9

Concentration s of Noxious Chemical Species in the

Flue Gases During the Polystyrene Series, in ppm by

Volume of Dry Gas, Actual an d Corrected to 12% CO2

Test No.

PS added

CI-, actual*

corrected

F-, actual

corrected

CN-, actual

corrected

NO, actual

corrected

P04=

corrected

S02, actual

currected

Organic acids,

as CH3COOH, actual

corrected

Aldehydes, as HCHO, actual

corrected

8-1

None

223

438

7.0

13.7

<0.01

<0.02

35.3

69.2

0.54

1.06

44.8

87.9

41.7

81.8

1.2

2.4

8-2

2%

242

475

5.9

11.6

<0.01

<0.02

40.2

79.2

1.3

2.6

32.4

63.5

54.1

106.1

1.6

3.1

* Average of scrubber and NaOH/impinger methods.

8-3

4%

226

450

6.5

13.0

<0.01

<0.01

37.6

75.0

0.21

0.42

31.1

62.0

77.5

154.5

1.4

2.8

Tests were not run for phosgene and free chlorine, as the poly­styrene contained no chlorine.

As the polystyrene contained only 0.0 2 percent suI-fur as compared with 0.10 percent for refuse, the S02

concentrations in the flue gas decreased as more PS was added to the refuse.

The concentration of organic acids in the flue gas in-creased with the addition of PS to the refuse, which in-dicates that turbulence in the furnace was not fully ade-quate. The increase of NO during the PS runs was slight, and within normal variations.

Chlorides in the flue gas were removed with "'Iicien-cies of 8 2.7 to 94.4 percent by the miniature scrubber. The chlorides were over 90 percent HC!. The scrubber water had a pH of 1.6 to 1. 8. The base refuse was the sole source of the chlorides. The other noxious gases were in low concentration and did not vary significant-ly as the result of PS additions.

Polyurethane (PU)

The three tests of the PU series were conducted in Furnace No. 2 on successive days. Table 10 presents the general combustion results.

The low arch and flue-gas temperature are the result of the unevenly wet and dry condition of the base refuse. Despite the nitrogen and chlorine content of the plastics, the blocks burned rapidly. After the furnace heat had

Table 11

Concentrations of Noxious Chemical Species in the Flue Gases

During the Polyurethane Series, in ppm by Volume of Dry Gas,

Actual and Corrected to 12% CO2

Test No. C-l C-2 C-3

PU added None 2"k 4%

CI-, actual* 248 320 319

corrected 530 689 751

F-, actual 5.0 16.8 12.6

corrected 10.7 36.2 29.7

CN-, actual <0.01 <0.01 <0.01

corrected <0.02 <0.02 <0.02

NO, actual 32.2 39.6 39.5

corrected 68.8 85.3 93.0

P04 = , actual 0.3 1 4.7 5.5

corrected 0.66 10.1 12.9

S02, actual 26. 1 34.4 32.7

corrected 55.7 74.0 77.0

O rganic acids

as CH3COOH, actual 73.9 78.5 73. 1

corrected 158 169 172

Aldehydes, as HCHO, actual 5.2 5.1 5.2

corrected 1 1. 1 1 1.0 12.2

* Average of scrubber and NaOH/impinger methods.

Tests were not run for phosgene and free chlorine, as the polyurethane contained only a small amount of c hlorine.

240

Table 12

General Combustion Performance During PVC Series

Test No. 0-1 0-2 0-3 0-4

PVC added, % of refuse None 2% None 4%

Refuse, Ib/h 15,667 17,000 17,000 14,667

PVC, lb/h 0 --..liQ. 0 587

Total,lb/h 15,667 17,340 17,000 15,254

F urnace arch, F 1 13 1 1585 1704 1697

Flue gas, F 856 1024 1 105 1 155

Flue gas analysis (Orsat),

dry vol. % CO2 3.64 4.92 4.99 5.36

CO 0.0 0.0 0.0

02 16.46 15.13 15.20 14.92

N2 79.9 79.95 79.81 79.72

Burnout, ft from end of grate 2 0 12 11.8

Smoke, Ringelmann 0. 189 0.036 0.086 0.043

Odor Units of flue gas 20* 25 2 20

* I t should be noted tha t the burning of normal refuse in this case resul ted in an odor level well above that recorded for all other control samples. The cause was wet refuse that did not produce suffic iently high tempera tures to burn all the odorous organic gases.

Table 13

Concentrations of Noxious Chemical Species in the

Flue Gases During the Polyvinyl Chloride Series, in ppm by

Volume of Dry Gas, Actual and Corrected to 12% CO2

Test No. 0-1 0-2 0-3 0-4

PVC added None 2"10 None 4%

CI-, ac tual* 138 816 304 1354

corrccted 455 1990 732 3030

F-, actual 0.92 4.6 2.3 2.8

corrected 3.03 I I.2 5.5 6.3

CN-, actual <0.0 1 <0.0 1 <0.0 1 <0.0 1

corrected <0.03 <0.02 <0.02 <0.02

NO, actual 25.3 40.6 23.3 46.2

corrected 83.4 99.1 56. 1 103

P04 =, ac tual 0.27 0.0 0. 15 0.0

corrected 0.89 0.0 0.36 0.0

S02, actual 39.8 37.6 32.9 38.6

corrected 132 9 1.7 79.1 86.4

O rganic acids as

C H3COOH, actual 30.3 26.4 48.2 44.4

corrected 100 64.5 116 99.3

Alde hydes, as HC HO, actual 1.8 3.8 1.9 5.2

corre.:ted 5.9 9.3 4.6 11.6

Phosgene (COCl2) ac tual not detected

Cl2, ac tua.1 not detected

* Average of scrubber and NaOH/impinger methods.

devolatilized the foam blocks on the top of the fuel bed, some of the light char was lofted by jets of flame and air from below. Such char continued to burn in suspen­sion but may have contributed some soot to the flue gases.

While PU apparently hastened burnout of the refuse, the effect is obscured by the fact that a lower tonnage was charged when the plastic was being added. The slight­ly greater smoke density shown in the meter readings when PU was added may have been caused as much by the cooler furnace and flue gas temperatures as by the foam addition. The odor concentration in the flue gas was low in all tests of the series.

No evidence of melted polyurethane was found in the grate siftings, and the plastic did not clog the grates. Ex­posure to combustion temperatures converted PU to gas and a fragile, foamy char rather than a melt.

Table II reports the concentrations of noxious chem­ical species during the three PU tests. The chlorides in­creased, as would be expected because of the chlorine contribution of the polyurethane. The nitric oxide con­centration also increased slightly, indicating that some of the PU nitrogen may have oxidized or have been re­leased from the plastic in oxidized form. Likewise, phos­phorus in the PU probably increased the phosphate in the gases.

Organic acids were higher in the series because the gas temperatures were not high enough nor the turbu­lence adequate for burnout.

The efficiency of the miniature scrubber ranged from 79.7 to 86.9 percent during the series. The pH of the impinger and overflow water was 1.6-1.7, while that of the condenser water was 2.2 to 2.7.

Polyvinyl Chloride (PVC)

Control Test No. I was run simultaneously with Test No. 2, the latter with 2 percent addition of PVC to the base refuse. On the next day, control Test No.3 was run simultaneously with Test No.4, which had a 4 per­cent addition of PVC. As alternate grapple loads from the same refuse supply were fired to both furnaces, the variations in base refuse would hopefully have been kept to the maximum possible under the circumstances. Table 1 2 reports the general combustion results.

In actual practice wetter refuse was charged to Fur­nace No. I (Test D-I ), which depressed the arch and flue-gas temperatures. The burnout was near the end of the grate and some combustible was lost with the residue. The same wet refuse caused a similar effect in Furnace No.2 (Test D-2) but to a lesser extent. The traces of light smoke and the higher odor level for the flue gas were largely due to inadequate heat, indicated by re­duced temperatures.

241

Tests D-3 and D4 proceeded normally; tempera­tures were high and burnout was good. The odor con­centration increased in the flue gas samples when PVC was added and the presence of HCI was evident in the odor test.

PVC was not found in the grate siftings and there was no clogging of the grates during the PVC series.

Table 13 lists the concentrations of noxious chem­ical species in the flue gases during the four tests of the series. Of primary interest is the marked increase in chloride concentration, over 90 percent hydrogen chloride. No phosgene or free chlorine was detected.

Scrubber efficiencies of 81.9 to 94.4 percent were obtained in removing chlorides during the series. The pH of the impinger and over flow water ranged between 1.6 and 1.8, while the condensate pH was 1 .7 to 2.8.

Fly ash was collected in a small steel tub set on the floor of the flue during each of the four tests. The fly ash was caught and kept hot until removed at the end of each run. Analyses of the fly ash are given in Table 14. No significant differences were found between tests with and without PVC additions, as regards the metal. Water soluble Cl- in the PVC series fly ash ranged between 0.34 and 2.80 percent, while total phosphorus ranged between 0.69 and 0.79 percent. Hence, it must be concluded that CI and P are distributed between the flue gas and fly ash in the hot flue.

Elements sought but not detected included arsenic, barium, boron, bismuth, cadmium, cobalt, lithium, niobium, silver, tantalum and tungsten. No determina­tions were made for carbon, mercury, potassium, sulfur or tellurium.

CHLORIDE EM ISS IONS

Table 15 was produced by converting the chlorine and chloride data to pounds per hour for all tests. The conversion of ppm to pounds per hour was calculated by the following equation:

Lb CI/h = Scfm of dry flue gas x 60 x ppm x density of CI 1,000,000

= Scfm x ppm x 60 x 0.092Ib/ft3

1,000 ,000

= Scfm x ppm 181,000

Fig. 3 is a graphical presentation of the data in columns 3 and 8 of Table 15. The diagonal 100 percent line represents total conversion of refuse chlorine to gaseous chloride. The highest yield was 85 percent. Most of the points are scattered about the 62.5 percent line, which line representing Swedish findings of 60 to 65 percent conversion of refuse chlorine to HC!.

Table 14

Semi-quantitative Spectrographic Analysis of Fly Ash, %

Test No. 0-1 0-2 0-3 0-4

PVC added 0% 2% 0% 4%

Aluminum >10 >10 >10 > 1 0

Antimony <0 .0 1 <0.01 - - - not detected - - -

Calcium I to 10 1 to 10 1 to 10 1 to 10

Chromium 0.5 to 1 .0 0.5 to 1 .0 0.5 to 1 .0 0.5 to 1 .0

Copper 0 .05 to 0 . 1 0.05 t o 0.1 0.05 to 0 . 1 0.05 t o 0 . 1

Iron I to 10 I to 10 1 to 10 1 to 10

Lead 0 . 1 to 1 .0 0 . 1 to 1.0 0.1 to 1 .0 0 . 1 to 0.5

Magnesium 1 to 5 1 to 5 1 to 5 1 to 5

Manganese 0 .0 1 to 0 . 1 0.0 1 to 0 . 1 0.0 1 to 0 . 1 0.0 1 to 0 . 1

Molybdenum <0.0 1 <0.01 <0.0 1 <0 .0 1

Nickel 0.0 1 to 0.05 om to 0. 1 0.0 1 to 0 . 1 0.0 1 t o 0. 1

Sodium 5 to 10 5 to 10 5 to 10 5 to 10

Silicon > 10 > 1 0 > 10 > 1 0

Tin 0.0 1 to 0 . 1 0.0 1 t o 0 . 1 0.0 1 to 0. 1 0 .01 to 0 . 1

Titanium > 10 > 10 > 10 > 10

Vanadium <0.0 1 <0.0 1 <0.0 1 <0.0 1

Zinc 0.0 1 to 0 . 1 0 .01 t o 0 . 1 0.0 1 t o 0.1 0.01 to 0.1

Zirconium 0.0 1 to 0 .5 0.05 to 0 . 1 0 .0 1 to 0 . 1 0.0 1 to 0 . 1

Table 15

Comparison of Chlorine Input to Chloride in Flue Gas

- - - Lb/h - - - -

CI * in CI in - - - - Ppm of Chloride - - - - Dry CI- in

base added Total CI Flue Gas, Flue Gas,

Test No. refuse plastics charged NaOH/lmp. Scrubber Avg. Scfm Lb/h

Col. 2 3 4 5 6 7 8

A- I 78 0 78 220 2 1 3 217 30,100 36.1

A-2 73 0 73 1 14 138 126 37,700 26.3

A-3 72 0 72 20 1 20 1 36,000 40.0

B-1 82 0 82 190 256 223 33,800 4 1 .6

B-2 73 0 73 2 17 266 242 31,900 42.6

B-3 72 0 72 226 225 226 34 ,000 42.5

C-l 77 0 77 276 220 248 34,300 47.0

C-2 67 6.5 73.5 265 376 320 3 1 ,400 55.5

C-3 60 12 72 3 1 9 319 32,800 57.8

D - l 78 0 78 138 138 5 1 ,700 39.4

D-2 85 154 . 1 239 . 1 890 742 8 1 6 44,700 202

D-3 85 0 85 304 304 42,900 7 1 .9

D-4 73 266 339 1087 1620 1354 37,400 280

* Assuming 0.5% chlorine in base refuse.

242

350 ------------------------------, 0-4 ..

a: :J: ..... m

FIGURE 3. C HLOR I D E I N F LUE GASES'

300 ..J

o w (!) a:

250 � o w (I) ;:)

200 t!:i a: z w

150 � a: o ..J :J: o

o

VS. C HLO RINE IN REFUSE

S YMBOLS • PE SERIES , P S SERIES • PU SERIES .. PVC SERIES

50 100 150 200 250 CHLORIDE IN FLUE GASES , LB / H R

Fig. 3

If the chlorine content of the base refuse had been assumed as 0.4 percent instead of 0.5 percent, two of the points (Test D-2 and D-3) would have been to the right of the 100 percent line, i.e. the yield would have exceeded the input. Therefore, the original assumption of 0.5 percent chlorine in the base refuse was reasonable on the basis of percent knowledge. This is not to pre­clude the possibility of lower chlorine contents during the PE and PS series.

The nature of the chloride caught in the scrubber water and in the condensate was investigated to deter­mine whether it was exclusively HCl or whether ap­preciable amounts of other chlorides were present. While some fine dust entered the sampling probe, and was carried along into the scrubber, most of the fly ash in the gas entering the probe escaped capture because the probe was at right angles to the gas flow.

According to the March 1971 report "Plastics in Solid Waste" of the National Industrial Pollution Con­trol Council, PVC makes up less than 0.15 percent of all collected household, commerical and industrial waste.

243

TESTS FOR CHEM ICAL ATTACK OF GRATES

B Y PLASTICS

Cast iron and ferrous alloys used in grate construction are subjected to a harsh environment of heating, cooling, oxidation by air and moisture, and mechanical stresses. The grate surfaces are not completely flushed by cool ambient air on the upper side, but come into direct con­tact with raw organic refuse, with vapors such as acetic acid and steam from the pyrolysis of cellulose, and with incandescent carbon.

To determine whether soluble iron salts are produced from the combustion of the four test plastics on iron grates, tests were conducted in a muffle furnace. Sections of used Flynn and Emrich stoker grates identical to those used in the Babylon incinerator, were saw-cut to include one air slot and the adjacent iron ribs. The grate sections were heated in a muffle furnace to about 600 F to drive off any oil vapors and again washed and dried.

Strips of plastics, 1/4 x 1/ 2 x 1 in. long, were laid on the two ribs of the grate casting, after which the cast­ing was inserted in a muffle furnace heated to 1000 F. A cold iron plate 1/4 in. thick was positioned under the grate and a small air tube was inserted into the grate to provide combustion air. The furnace door was lowered part way and the power was left on to maintain furnace temperature.

The grate specimen was left in place 8 min , during which time the plastiC burned to a char deposit. The grate was removed and cooled by distilled wa ter, in which it was rewashed. The wash water was analyzed for water-soluble iron and chlorides.

The process was repeated for each plastic and for a control blank.

Reagents used for testing for water-soluble chlorides included silver nitrate (AgN03) which produced a white precipitate of silver chloride. Ammonium thiocyanate (NH4 SCN) was used to detect soluble iron (Fe+++), which produced the red iron thiocyanate. Ammonium hydroxide also shows the presence of a precipitate when soluble iron is present.

The tests were also performed on scrapings of scale from the grate castings prepared from a used Flynn and Emrich grate. By extraction with water, clearly positive evidence of Cl- was obtained. Washings containing pieces of scale were acidulated with a few drops of nitric acid. The resulting acid washing also tested positive for chlor­ide, with the further observation that the Cl- containing substance(s) apparently had a greater solubility in dilute HN03 than in water.

Effect of Polyethylene Plastic

No PE sample was burned on the grate casting as the PE plastics contained no chlorine.

Effect of Polystyrene Plastic

The casting was cleaned and subjected to a blank test in the muffle furnace, with no indication of Cl- present.

When PS was burned on the casting in the muffle furnace, some molten PS adhered to the iron and a loose char was also produced. The test for Fe+++ was weakly positive; the test for Cl- was negative.

Effect of Polyurethane Plastic

The casting was cleaned and subjected to a blank test in the n1'.Jffle furnace. A very weak indication of Fe+++ was noted but no Cl-.

When PU was burned on the casting the washings showed a very weak indication of Fe+++ and no indica­tion of Cl-, the latter despite the small amount of chlorine in the plastic.

Effect of Polyvinyl Chloride Plastic

The control test without PVC showed a very weak in­dication of Fe+++ but no chloride. When PVC was burned on the casting, and the char was removed, the casting wasrungs showed positive for Fe+++ and Cl-, evidence of slight chloride attack of the grate metal by burning PVC.

RES UL TS OF TESTS ON REFRACTORY BRIC KS

In all test cases, involving all four plastics, no distinct visual changes were noted on the surfaces of any of the

, new firebricks exposed to the hot flue gases which could be attributed to any of the plastics.

Each brick was washed with water after exposure during the full period of a test, and each washing was analyzed. The analytical results were essentially identical in all cases. No one specie was present in any greater amount than in wasrung from the blanks.

POTENTIAL CORROSION OF INCINERATOR

S YSTEMS BY H YDROGEN CHLORIDE AND

OTHER ACIDS

Historically, corrosion by pitting has been experi­enced in flue-gas scrubbers and associated pumps and piping of municipal incinerators. Stainless steel has

corroded less rapidly than mild steel in contact with the acid scrubber water. It is also known that fly ash in contact with scrubber water is helpful toward neutralizing the acid. Sodium carbonate treatment of scrubber water is feasible for maintaining a nearly neu­tral scrubber water, one which will reduce chloride (hydrogen ion) attack of iron.

Gas scrubbers l ined, with acid brick, rubber, and/or plastics are resistant to chloride attack, as are plastic piping and pipe linings.

Chloride attack of certain grades of stainless steel is known to occur under stress when wet with HCl as in scrubbers and fans.

Chloride attack and boiler tube wastage have been reported in Europe under special conditions of incin­erator/boiler design and operation, but these have been solved by protective ceramic coatings of affected areas. Battelle Memorial Institute is investigating boiler and scrubber corrosion from incinerator flue gases.

AC KNOWLEDGMENTS

The investigation was sponsored by The Society of the Plastics Industry, Inc., and monitored by the SPI Plastic Waste Management Committee. SP I members contributed the plastics burned on the tests. The Society committee and staff gave constant encouragement and assistance.

The Town of Babylon, New York, permitted the use of the town incinerator for the tests. Special thanks are given to Superintendent N. Paul DeGeorge and Foreman Ralph Ottavo. Refuse analyses were performed by Fuel Engineering Company of New York, Thornwood, New York. Chemical analysis of gaseous samples were conducted by Schwartzkopf Microanalytical labora­tory, Woodside, N.Y. and by Gollob Analytical Service Corp., Berkeley Heights, N.J.

Assisting on the tests were Edward Kaplin, research scientist; Daniel Kasner, associate research scientist; Donald Wilcox, associate research scientist; Charles Zimmer, senior technician; M . Cytter, gradua te student.

REFERENCES

[ 1 ] W. R. Niessen and S. H. Chansky, "The Nature of Refuse," Proceedings of the 1 9 70 National incinerator Can· ference, ASME, New York, N. Y . , 1970, pp. 1-24.

[ 2 ] E . R. Kaiser and A. A . Carolti, "Plastics in M unicipal Refuse Incineration ," report to SPI, April 1970.

244