817 P PARTICULATE EMISSIONS EMISSION STANDARDS Allowable levels of particulate emissions are specified in several different ways, having somewhat different meth- odologies of measurement and different philosophies of important criteria for control. Permissible emission rates are in a state of great legislative flux both as to the definition of the suitable measurement and to the actual amount to be allowed. This section summarizes the various types of quan- titative standards that are used in regulating particulate emis- sions. For a detailed survey of standards, the reader should consult works by Stern, 1 Greenwood et al. , 2 and the Public Health Service. 3 A recent National Research Council report proposes future studies on the nature of particulate emissions, their effect on exposed populations and their control 4 . Friedrich and Reis 5 have reported the results of a 10-year multinational European study on characteristics, ambient concentrations and sources of air pollutants. The following paragraphs give an overview of standards for ambient particulate pollution and source emission. The precise and practical methodology of making accurate and/ or legally satisfactory measurements is beyond the scope of this article. Books such as those by Katz, 6 Powals et al. , 7 Brenchly et al. , 8 and Hawksley et al. 9 should be consulted for detailed sampling procedures. In the Federal Register USEPA announced the implementation of the PM-10 regu- lations (i.e., portion of total suspended particulate matter of 10 µ m or less particle diameter). 40,41 Ringlemann Number Perhaps the first attempt at quantifying particulate emis- sions was developed late in the 19th century by Maximilian Ringlemann. He developed the concept of characterizing a visible smoke plume according to its opacity or optical den- sity and originated the chart shown in Figure 1 as a conve- nient scale for estimation of opacity. The chart consists of four grids of black lines on a white background, having frac- tional black areas of 20, 40, 60 and 80% which are assigned Ringlemann Numbers of 1–4. (Ringlemann 0 would be all white and Ringlemann 5 all black.) For rating a smoke plume, the chart is held at eye level at a distance such that chart lines merge into shades of grey. The shade of the smoke plume is compared to the chart and rated accordingly. The history and use of the Ringlemann chart is covered by Kudlich 8 and by Weisburd. 9 In actual practice, opacity is seldom determined by use of the chart, although the term Ringlemann Number persists. Instead, observers are trained at a “smoke school.” 10 Test plumes are generated and the actual percentage of light atten- uation is measured spec-trophotometrically within the stack. Observers calibrate their perception of the emerging plume against the measured opacity. Trained observers can usu- ally make readings correct to Ϯ 1/2 Ringlemann number. 11,13 Thus, with proper procedures, determination of a Ringlemann Number is fairly objective and reproducible. The Ringlemann concept was developed specifically for black plumes, which attenuate skylight reaching the observ- er’s eye and appear darker than the sky. White plumes, on the other hand, reflect sunlight and appear brighter than the background sky so that comparison to a Ringlemann chart is meaningless. The smoke school approach is quite applicable, however. Observations of a white plume are calibrated against the measured light attenuation. Readings of white plumes are somewhat more subject to variation due to relative locations of observer, plume, and sun. It has been found that observa- tions of equivalent opacity taken with the observer facing the sun are about 1 Ringlemann number higher 13 than those FIGURE 1 Ringlemann’s scale for grading the density of smoke. C016_001_r03.indd 817C016_001_r03.indd 817 11/18/2005 1:15:33 PM11/18/2005 1:15:33 PM © 2006 by Taylor & Francis Group, LLC 818 PARTICULATE EMISSIONS taken in the prescribed method with the sun at the observer’s back. Nevertheless, when properly made, observations of Ringlemann numbers are reproducible among observers and agree well with actual plume opacity. Opacity regulations specify a maximum Ringlemann number allowable on a long-term basis but often permit this to be exceeded for short prescribed periods of time. For instance, a typical requirement specifies that emissions shall not exceed Ringlemann 1, except that for up to 3 min/hr emis- sions up to Ringlemann 3 are permitted. This allowance is of considerable importance to such operation as soot blowing or rapping of electrostatic precipitator plates, which produce puffs to smoke despite on overall very low emission level. Federation regulations of the Environmental Protection Agency 14 specify that opacity observations be made from a point perpendicular to the plume, at a distance of between two stack heights and one quarter of a mile, and with the sun at the observer’s back. For official certification, an observer under test must assign opacity readings in 5% increments (1/4 Ringlemann number) to 25 plumes, with an error not to exceed 15% on any single reading and an average error (excluding algebraic sign of individual errors) not to exceed 7.5%. Annual testing is required for certification. In view of previous studies, 11,13 this is a very high standard of perfor- mance and probably represent the limits of visual quantifica- tion of opacity. Perhaps the greatest advantage of the Ringlemann Number approach is that it requires no instrumentation and very little time and manpower. Readings can usually be made by con- trol authorities or other interested parties without entering the premises of the subject source. Monitoring can be done very frequently to insure continual, if not continuous, compliance of the source. Finally, in terms of public awareness of par- ticulate emissions, plume appearance is a logical candidate for regulation. Air pollution is, to a great extent, an aesthetic nuisance affecting the senses, and to the extend that plume appearance can be regulated and improved, the visual impact of pollution is reduced. The Ringlemann Number concept has drawbacks reflecting its simple, unsophisticated basis. Most serious is that, at pres- ent, there is no really quantitative relationship between stack appearance and the concentration of emissions. Additional factors; such as particle size distribution, refractive index, stack diameter, color of plume and sky, and the time of day, all have a marked effect on appearance. On a constant weight concentration basis, small particles and large smoke stacks will produce a poor Ringlemann Number. Plumes that have a high color contrast against the sky have a very strong visual impact that does not correspond closely to the nature of the emissions. For example, a white plume may be highly visible against a deep blue sky, but the same emission can be practically invis- ible against a cloudy background. As a result, it is often dif- ficult to predict whether or not proposed control devices for a yet unbuilt plant will produce satisfactory appearance. Certain experience factors are presented in Table 1 for emissions, mea- sured on a weight concentration basis, which the Industrial Gas Cleaning Institute has estimated will give a Ringlemann 1 or a clear stack. A second objection is that Ringlemann number is a purely aesthetic measurement which has no direct bearing on physiological effects, ambient dirt, atmospheric corro- sion, or any of the other very real and costly effects of par- ticulate air pollution. There is some concern that regulations of very low Ringlemann numbers will impose very costly control measures upon sources without producing a com- mensurate improvement in the quality of the environment. Thus a high concentration of steam will produce a visually prominent plume, but produce virtually no other undesirable effects. Opacity restrictions are usually waived if opacity is due entirely to steam but not if any other particles are pres- ent, even if steam may be the major offender. Instrumental Opacity Many factors affecting the visual appearance of a smoke plume are external variables, independent of the nature of the emissions. In addition, visual reading cannot be taken at all at night; and manpower costs for continuous daytime moni- toring would be prohibitive. For these reasons, instrumental measurements of plume opacity are sometimes desirable. A typical stack mounted opacity meter is shown in path traversing the smoke stack, and a phototube receiver which responds to the incident light intensity and, hence, to the light attenuation caused by the presence of smoke. Various techniques including beam splitting, chopper stabi- lization, and filter comparison are used to maintain stable baselines and calibrations. At present, however, there is no way to distinguish between dust particles within the gas stream and those which have been deposited on surfaces in the optical path. Optical surfaces must be clean for mean- ingful measurements, and cleanliness is difficult to insure for long periods of time in dusty atmosphere. The tendency, therefore, is for such meters to read high, indicating more smoke than is actually present. For this reason, and because of reluctance to have a continuous record of emissions, there has not been a very strong push by industries to supplant Ringlemann observations with opacity meters. Stack mounted opacity meters, of course, will not detect detached plumes, which may contribute to a visual Ringlemann observation. Detached plumes are due to particles formed by condensation or chemical reaction after gas leaves the stack and are thus beyond detection of such a meter. At present, Texas is the only state with emissions control regulations based on use of opacity meters, 15 as described by McKee. 11 The Texas regulations is written so that smoke of greater optical density (light attenuation per unit length of light path) is permitted from low velocity stacks or small diameter ones. Basically, a minimum transmittance of 70% is allowed across the entire (circular) stack diameter if the stack has an exit velocity of 40 ft/sec, and adjustment equa- tions are provided for transmittance and/or optical path length if non-standard velocity or path length is used. Perhaps the greatest dissatisfaction with emission regula- tions based either on visual observation number or on instru- mental opacity is due to the fact that there is presently no C016_001_r03.indd 818C016_001_r03.indd 818 11/18/2005 1:15:34 PM11/18/2005 1:15:34 PM © 2006 by Taylor & Francis Group, LLC Figure 2. It consists, basically, of a light source, an optical PARTICULATE EMISSIONS 819 TABLE 1 Industrial process emissions expected to produce visually clear (or near clear) stack Industrial classification Process Grains/ACF @Stack exit temp. (°F) Utilities and industrial power plant fuel fired boilers Coal—pulverized 0.02 @ 260–320 Coal—cyclone 0.01 @ 260–320 Coal—stoker 0.05 @ 350–450 Oil 0.003 @ 300–400 Wood and bark 0.05 @ 400 Bagasse Fluid 0.04 @ 400 Fluid code 0.015 @ 300–350 Pulp and paper Kraft recovery boiler 0.02 @ 275–350 Soda recovery boiler 0.02 @ 275–350 Lime kiln 0.02 @ 400 Rock products—kiln Cement—dry 0.015 @ 450–600 Cement—wet 0.015 @ 450–600 Gypsum 0.02 @ 500 Alumina 0.02 @ 400 Lime 0.02 @ 500–600 Bauxite 0.02 @ 400–450 Magnesium oxide 0.01 @ 550 Steel Basic oxygen furnace 0.01 @ 450 Open hearth 0.01–0.015 ≈450–600 Electric furnace 0.015 @ 400–600 Sintering 0.025 @ 300 Ore roasters 0.02 @ 400–500 Cupola 0.015 @ 0.02 ≈250–400 Pyrites roaster 0.02 @ 400–500 Taconite roaster 0.02 @ 300 Hot scarfing 0.025 @ 250 Mining and metallurgical Zinc roaster 0.01 @ 450 Zinc smelter 0.01 @ 400 Copper roaster 0.01 @ 500 Copper reverberatory furnace 0.015 @ 550 Copper converter 0.01 @ 500 Aluminum—Hall process 0.075 @ 300 Soderberg process 0.003 @ 200 Ilmenite dryer 0.02 @ 300 Titanium dioxide process 0.01 @ 300 Molybdenum roaster 0.01 @ 300 Ore beneficiation 0.02 @ 400 Miscellaneous Refinery cataly stregenerator 0.015 @ 475 Incinerators—Municipal 0.015 @ 500 Apartment 0.02 @ 350 Spray drying 0.01 @ 400 Precious meal—refining 0.01 @ 400 C016_001_r03.indd 819C016_001_r03.indd 819 11/18/2005 1:15:34 PM11/18/2005 1:15:34 PM © 2006 by Taylor & Francis Group, LLC 820 PARTICULATE EMISSIONS quantitative procedure for design of equipment to produce complying plumes. Equipment vendors will usually guar- antee collection efficiency and emission concentrations by weight, but they will not give a guarantee to meet a specified opacity. This is indeed a serious problem at a time when a large precipitator installation can cost several million dollars and take twenty months to fabricate and install. Overdesign by a very conceivable factor of two can be very expensive in unneeded equipment. Underdesign can mean years of delay or operation under variance or with penalty payments. Some progress has been made in applying classical theo- ries of light scattering and transmission to the problem of predicting opacity. This effort has been greatly hampered by paucity of data giving simultaneous values of light attenua- tion, particle size distribution, and particle concentration in a stack. Perhaps the most comprehensive work to date has been that of Ensor and Pilat. 16 Weight Limits on Particulates Perhaps the least equivocal method of characterizing and specifying limits on particulate emissions is according to weight, either in terms of a rate (weight of emissions per unit time) or in terms of concentration (weight per unit volume). Measurement of emission weights must be done by iso- kinetic sampling of the gas stream, as outlined in the follow- ing section on measurement. Although the principles of such measurement are simple, they are difficult and time consum- ing when applied with accurate methodology to commer- cial installations. For this reason, such measurements have not previously been required in many jurisdictions and are almost never used as a continual monitoring technique. Limits on weight rate of emissions are usually dependent on process size. Los Angeles, for instance, permits emissions to be proportional to process weight, up to 40 lbs/hr particu- lates for a plant processing 60,000 lbs/hr of material. Larger plants are limited to 40 lbs/hr. For furnaces, the determining factor is often heat input in BTU/hr rather than process weight. In cases where a particular plant location may have several independent units carrying out the same or similar processes, regulations often require that the capacities be combined for the purposes of calculating combined emissions. Concentration limits are usually independent of process size. For instance, the EPA specifies incinerator emission of 0.08 grains particulates per standard cubic foot of flue gas (0.18 gm/NM 3 ) Dilution of the flue gas with excess air is usu- ally prohibited, or else correction must be made to standard excess air or CO 2 . Ground Level Concentrations of Suspended Particulates A limit on ground level concentration of particulates is an attempt to regulate emissions in accordance with their impact on population. A smoke stack acts as a dispersing device, and such regulations give incentive to build taller stacks in optimum locations. In theory, ground level concentrations can be measured directly. Usually, however, emissions are measured in the stack, and plume dispersion equations are then used to cal- culate concentration profiles. Plume dispersion depends on stack height, plume buoyancy (i.e. density relative to ambi- ent air), and wind velocity, and wind patterns. In addition, plumes are never stationary but tend to meander; and cor- rection factors are usually applied to adjust for the sampling time at a fixed location. Dispersion calculations are usually easier than direct ground level measurements; and in cases where many different sources are present, calculation offers the only practical way to assess the contributions of a spe- cific source. A recent evaluation of plume dispersion models is given by Carpenter et al. 15 In some states, a plume dispersion model is incorporated into a chart which gives an allowable weight rate of emissions as a function of effective stack height and distance from prop- erty lines. An example of this approach is shown in Figure 3. FIGURE 3 Emission requirements for fine particles based on plume dispersion model (New Jersey Air Pollution Code). FIGURE 2 Stack mounted opacity meter (Bailey Meter Co.). SPOTLAMP LIGHT SOURCE SPACED FLANGES FOR AIR INLET SMOKE OR DUST PASSAGE BOLOMETER SPACED FLANGES FOR AIR INLET C016_001_r03.indd 820C016_001_r03.indd 820 11/18/2005 1:15:34 PM11/18/2005 1:15:34 PM © 2006 by Taylor & Francis Group, LLC PARTICULATE EMISSIONS 821 The particular regulation shown also accounts for differing toxicity of certain particulates and allocates the emission factors of Table 2 accordingly. Very often permissible ground level concentrations are set according to other sources in the area. Thus a plant would be allowed greater emissions in a rural area than in a heavily industrialized neighbourhood. Dust fall A variant on the ground level concentration limit is a dustfall limit. This basically superimposes a particle settling velocity on ground level concentration to obtain dustfall rates in weight per unit area per unit time. This is a meaningful regulation only for large particles and is not widely legislated at present. Federal Clean Air Statutes and Regulations The major federal statutes covering air pollution are PL 88– 206 (The Clean Air Act of 1963), PL 90–148 (The Air Quality Act of 1967) PL 92–157, PL 93–115, PL 95–95 (The Clean Air amendments of 1977), and PL 95–190, Administrative stan- dards formulated by the Environmental Protection Agency (EPA) are given in the Code of Federal Regulations Title 40, parts 50, 51, 52, 53, 58, 60, 61, and 81. The EPA has established National Ambient Air Quality Standards (NAAQS). For suspended particulate matter the primary standard (necessary to protect the public health with an adequate margin of safety) is 75 µ g/M 3 annual geometric mean with a level of 260 µ g/M 3 not to be exceeded more than once per year. All states have been required to file state implementation plants (SIP) for achieving NAAWS. It is only through the SIP’s that existing pollution sources are regulated. The EPA requires no specific state regulations for limits on existing sources, but suggestions are made for “emission limitations obtainable with reasonable available technology.” Some of the reasonable limits proposed for particulates are: 1) Ringlemann 1 or less, except for brief periods such as shoot blowing or start-up. 2) Reasonable precautions to control fugitive dust, including use of water during grading or demo- lition, sprinkling of dusty surfaces, use of hoods and vents, covering of piles of dust, etc. 3) Incinerator emission less than 0.2 lbs/100 lbs refuse charged. 4) Fuel burner emissions less than 0.3 lbs/million BTU heat input. 5) For process industries, emission rates E in lbs/hr and Process weight P in tons/hr according to the relationships: E = 3.59 P 0.62 for P р 30 tons/hr. E = 17.31 P 0.16 for P у 30 tons/hr. “Process weight” includes all materials introduced to the process except liquid and gaseous fuels and combustion air. Limits should be set on the basis of combined process weights of all similar units at a plant. In considering what emission limits should be estab- lished, the states are encouraged to take into account local condition, social and economic impact, and alternate control strategies and adoption of the above measures is not manda- tory. It is expected, however, that such measures will become the norm in many areas. For new or substantially modified pollution sources, the EPA has established new source performance standards. The standards for particulate emissions and opacity are given in Table 3. Owners may submit plants of new sources to the EPA for technical advice. They must provide ports, plat- forms, access, and necessary utilities for performing required tests, and the EPA must be allowed to conduct tests at rea- sonable times. Required records and reports are available to the public except where trade secrets would be divulged. The states are in no way precluded from establishing more stringent standards or additional procedures. The EPA test method specified for particulates measures only materials collectable on a dry filter at 250°F an does not include so called condensables. TABLE 2 Pollution Control Code) Material Effect factor Fine Solid Particles All materials not specifically listed hereunder 1.0 Antimony 0.9 A-naphthylthiourea 0.5 Arsenic 0.9 Barium 0.9 Beryllium 0.003 Cadmium 0.2 Chromium 0.2 Cobalt 0.9 Copper 0.2 Hafnium 0.9 Lead 0.3 Lead arsenate 0.3 Lithium hydride 0.04 Phosphorus 0.2 Selenium 0.2 Silver 0.1 Tellurium 0.2 Thallium 0.2 Uranium (soluble) 0.1 Uranium (insoluble) 0.4 Vanadium 0.2 C016_001_r03.indd 821C016_001_r03.indd 821 11/18/2005 1:15:34 PM11/18/2005 1:15:34 PM © 2006 by Taylor & Francis Group, LLC Emission effect factors (for use with Fig. 3) (New Jersey Air Chapter 1, Sub-chapter C, with regulations on particulates in 822 PARTICULATE EMISSIONS In addition to new source performance standards, major new stationary sources and major modifications are usually subject to a “Prevention of Significant Deterioration” review. If a particulate source of more than 25 tons/year is located in an area which attains NAAQS or is unclassifiable with respects to particulates, the owner must demonstrate that the source will not violate NAAQS or PSD concentration incre- ments. This requires modelling and preconstruction moni- toring of ambient air quality. If the new or expanded source is to be located in an area which does not meet NAAQS, then emission from other sources must be reduced to offset the new source. The regulation regarding emission offsets and prevention of significant deterioration are relatively recent. A summary of federal regulations as of 1981 has recently been published as a quick guide to this rapidly changing field. 18 In recent years, regulation of particulate emissions from mobile sources has been initiated. The burden is essentially on manufacturers of diesel engines. Because the emission requirements and test procedures are quite complex and because the target is highly specific, a comprehensive discus- sion is beyond the scope of this article. Some representative standards are: Diesel engines for urban buses, 0.019 grams/ megajoule, and other diesel engines for road use, 0.037 grams/ megajoule: 19 Non-road diesel engines, 1 gram/kilowatt-hour for sizes less than 8 kilowatts in tier 1 down to 0.2 grams/ kilowatt-hour for units larger than 560 kilowatts in tier 2. 20 Locomotives, 0.36 grams/bhp-hr for switching service in tier 1 down to 0.1 grams/bhp-hr for line service in tier 3. 21 Marine diesel engines, 0.2 grams/KwH to 0.5 grams/KwH, depending on displacement and tier. 22 Note that the emission units above are as specified in the printed regulation. Particulate emission standards are also being promulgated by agencies other than the Environmental Protection Agency. In general, these are workplace standards. An example would be the standard for mobile diesel-powered transporta- tion equipment promulgated by the Mine Safety and Health Administration. This specifies that the exhaust “shall not con- tain black smoke.” 23 MEASUREMENT OF PARTICULATE EMISSIONS As a first step in any program for control of particulate emis- sions, a determination must be made of the quantity and nature of particles being emitted by the subject source. The quantity of emissions determines the collection efficiency and size of required cleanup equipment. The particle size and chemical properties of the emitted dust strongly influence the type of equipment to be used. Sampling for this purpose has been mainly a matter of industrial concern. A last step in most control programs consists of measuring pollutants in the cleaned gas stream to ensure that cleanup equipment being used actually permits the pertinent emission targets to be met. With increasing public concern and legislation on air pollution, sampling for this purpose is increasingly required by statute to determine compliance with the pertinent emis- sion regulations. To this end the local pollution control authority may issue a comprehensive sampling manual which sets forth in considerable detail the procedures to be used in obtaining raw data and the computations involved in calculating the pertinent emission levels. Complete and comprehensive source testing procedures are beyond the scope of this paper. References 24–28 give detailed instruction for performance of such tests. Sampling of gas streams, especially for particulates, is simple only in concept. Actual measurement require special- ized equipment, trained personnel, careful experimental and computational techniques, and a considerable expenditure of time and manpower. Matters of technique and equipment are covered in source testing manuals as mentioned above and are briefly summarized later in this paper. Two addi- tional complicating factors are usually present. First is the frequent inaccessibility of sampling points. These points are often located in duct work 50–100 ft above ground level. Scaffolding must often be installed around the points, and several hundred pounds of equipment must be lifted to that level. Probe clearances are often critical, for in order to make a sample traverse on 12 ft dia. stack, a 14 ft probe is needed, and clearance must be available for insertion into the sam- pling port as well as a means for suspending the probe from above. At least one professional stack sampler is an ama- teur mountain climber and puts his hobby to good use on the job. A second complicating factor is the adverse physical conditions frequently encountered. A somewhat extreme but illustrative example is a refinery stream recently sampled. Gas temperature was 1200°F requiring special probes and gas- kets and protective clothing for the workers. The gas stream contained 10% carbon monoxide creating potential hazards of poisoning and explosion especially since duct pressure was slightly above that of the atmosphere. Temperature in the work area was in excess of 120°F contributing further to the difficulty of the job. In preparation for a sampling program, work platforms or scaffolding and valved sample ports must be installed. All special fittings for adapting the sampling probes to the ports should be anticipated and fabricated. Arrangements must be made with plant operating personnel to maintain steady operating conditions during the test. The test must be carefully planned as to number and exact location of tra- verse sample points, and probes should be premarked for these locations. Flow nomographs for sampling nozzles should be made; and all filters, impingers, and other ele- ment of sampling trains should be tared. With that advance preparation a 3 man sampling team would require 1–2 days to position their equipment and make gas flow measure- ments and 2 sample transverses at right angles in a large duct or stack. Measurement of Gas Flow Rates A preliminary step in determination of emission rates from a stack is measurement of the gas flow rate. Detailed pro- cedures in wide use including the necessary attention to technique have been published by the ASME, 20 ASTM, 19 the Environmental Protection Agency, referred to as EPA, 21 C016_001_r03.indd 822C016_001_r03.indd 822 11/18/2005 1:15:34 PM11/18/2005 1:15:34 PM © 2006 by Taylor & Francis Group, LLC PARTICULATE EMISSIONS 823 TABLE 3 Federal Limits of Particulate Emissions from New Stationary Sources (Through 2004 Codified in CFR, Title 40. Chapter 1/Part 60) Subpart Source Particulate Emissions Opacity (%) D Fossil fired steam generators 13 ng/j 20* (27% for 6 min/hr) Da Electric utility steam generators 43 ng/j 20* (27% for 6 min/hr) Db Industrial/commercial/institutional 22 to 86 ng/j 20* steam generators depending on fuel, size, construction date (27% for 6 min/hr) Dc Small industrial/commercial steam generators 22 to 43 ng/j 20* depending on fuel, size (27% for 6 min/hr) E Incinerators 0.18 g/dscm — F Portland cement kiln 0.15 kg/ton 20* clinker cooler 0.05 kg/ton 10* other facilities — 10 G Nitric acid — 10 H Sulfuric Acid 0.075 kg/ton 10 I Hot mix asphalt 90 mg/dscm 20 J Refinery—fluid catalytic cracker regenerator 1 kg/1000 kg coke burned 30* (6 min/hr exception) L Secondary lead smelters cupola or reverberatory furnace 50 mg/dscm 20 pot furnace — 10 M Secondary brass and bronze production 50 mg/dscm 20 N Basic oxygen steel, primary emission 50 mg/dscm 10 with closed hooding 68 mg/dscm (20% once per production cycle) Na Basic oxygen steel, secondary emissions from shop roof — 10 (20% once per production cycle) from control device 23 mg/dscm 5 O Sewage plant sludge incinerator 0.65 g/kg dry sludge 20 P Primary copper smelters, dryer 50 mg/dscm 20* sulfuric acid plant — 20 Q Primary zinc smelters, sintering 50 mg/dscm 20* sulfuric acid plant — 20 R Primary lead smelters, sintering or furnaces 50 mg/dscm 20* sulfuric acid plant — 20 S Primary aluminum reduction pot room — 10 Anode bake plant — 20 Y Coal preparation thermal dryer 0.07 g/dscm 20 pneumatic coal cleaning 0.04 g/dscm 10 conveying, storage, loading — 20 (continued) C016_001_r03.indd 823C016_001_r03.indd 823 11/18/2005 1:15:34 PM11/18/2005 1:15:34 PM © 2006 by Taylor & Francis Group, LLC 824 PARTICULATE EMISSIONS TABLE 3 (continued) Subpart Source Particulate Emissions Opacity (%) Z Ferroalloy production control device; silicon, ferrosilicon, 0.45 kg/MW-hr 15* calcium silicon or silicomanganese zirconium alloys control device; production of other alloys 0.23 kg/MW-hr 15* uncontrolled emissions from arc furnace — Not visible uncontrolled emissions from tapping station — Not visible for more than 40% of tap period dust handling equipment — 10 AA Electric arc steel plants control device 12 mg/dscm 3* shop exit due to arc furnace operation — 6 except during charging — 20 except during tapping — 40 dust handling equipment — 10 BB Kraft pulp mills recovery furnace smelt dissolving tank lime kiln, gas fired oil fired 10 g/dscm 0.1 g/kg black liquor solids 0.15 g/dscm 0.30 g/dscm 35 — — — CC Glass manufacture, standard process container glass pressed & blown glass, borosilisate pressed & blown glass, soda lime & lead pressed & blown glass, other compositions wool fiberglass flat glass Gas fuel l0.1 g/kg glass 0.5 g/kg 0.1 g/kg 0.25 g/kg 0.25 g/kg 0.225 g/kg Oil fuel l0.13 g/kg glass 0.65 g/kg 0.13 g/kg 0.325 g/kg 0.325 g/kg 0.225 g/kg — — — — — — Glass manufacture, modified process container, flat, pressed, blown glass, soda lime container, flat, pressed, blown glass, borosilicate textile and wood fiberglass 0.5 g/kg 1.0 g/kg 0.5 g/kg * * * DD Grain elevators column dryer, plate perforation >2.4 mm rack dryer, exhaust screen filter cans thru 50 mesh other facilities fugitive, truck unloading, railcar loading/unloading fugitive, grain handling fugitive, truck loading fugitive, barge or ship loading — — 0.023 g/dscm — — — — 0 0 0 5 0 10 20 GG Lime rotary kiln 0.30 g/kg stone feed 15* LL Metallic mineral processing stack emissions fugitive emissions 0.05 g/dscm — 7 10 NN Phosphate rock dyer calciner, unbeneficiated rock calciner, beneficiated rock rock grinder 0.03 g/kg rock 0.12 g/kg rock 0.055 g/kg rock 0.0006 g/kg rock 10* 10* 10* 0* PP Ammonium sulfate manufacture, dryer 0.15 g/kg product 15 (continued) C016_001_r03.indd 824C016_001_r03.indd 824 11/18/2005 1:15:34 PM11/18/2005 1:15:34 PM © 2006 by Taylor & Francis Group, LLC PARTICULATE EMISSIONS 825 TABLE 3 (continued) Subpart Source Particulate Emissions Opacity (%) UU Asphalt roofing shingle of mineral-surfaced roll saturated felt or smooth surfaced roll Asphalt blowing still with catalyst addition with catalyst addition, #6 oil afterburner no catalyst no catalyst, #6 oil afterburner Asphalt storage tank Asphalt roofing mineral handling and storage 0.04 g/kg 0.4 g/kg 0.67 g/kg 0.71 g/kg 0.60 g/kg 0.64 g/kg 20 20 — — — — 0 1 AAA Residential wood heaters with catalytic combustor no catalytic combustor 4.1 g/hr 7.5 g/hr — — OOO Nonmetallic mineral processing stack or transfer point on belt conveyors fugitive emissions crusher fugitive emissions 0.05 g/dscm — — 7 10 15 PPP Wool fiberglass insulation 5.5 g/kg UUU Calciners & dryers in mineral industries 0.092 g/dscm 10* *Continous monitoring by capacity meters required The above standards apply to current construction. Existing unmodified units may have lower standards. Many applications require continuous monitoring of operating variables for process and control equipment. the Lost Angeles Air Pollution Control district, referred to as APCD, 21 and the Western Precipitation Division, referred to as WP. 21 This article will only treat the general procedures and not significant differences between popu- lar techniques. Velocity Traverse Points Because of flow non-uniformity, which almost invariably occurs in large stacks, the stack cross section in the sampling plane must be divided into a number of smaller areas and gas velocity determined sepa- rately in each area. Circular ducts are divided by concentric circles, and 2 velocity traverses are made at right angles. Figure 4 shows a typical example. Location of the sample points can be determined from the formula RD n N n ϭ Ϫ21 2 where R n = distance from center of duct to the “ n th” point from the center D = duct diameter n = sample point number, counting from center N = total number of measurement points in the duct. The number of sample points along one diameter is N /2. For rectangular ducts the cross section is divided into N equal rectangular areas such that the ratio of length to width of the areas is between one and two. Sample points are at the center of each area. The number of traverse points required is usually speci- fied in the applicable test code as a function of duct area or diameter. Representative requirements are shown in Table 4. S-6 S-5 S-4 E-4E-5E-6 E-3 E-2 E-1 EAST S-3 S-2 S-1 SOUTH R 3 R 2 R 1 FIGURE 4 Velocity and sampling traverse positions in circular ducts. C016_001_r03.indd 825C016_001_r03.indd 825 11/18/2005 1:15:35 PM11/18/2005 1:15:35 PM © 2006 by Taylor & Francis Group, LLC 826 PARTICULATE EMISSIONS Very often more points are required if the flow is highly non- uniform or if the sampling point is near an elbow or other flow disturbance. Figure 5 shows the EPA adjustment for flow nonuniformity. Velocity Measurement Velocity measurements in dusty gases are made with a type S (special or staubscheibe) pitot tube, shown in Figure 6, and a draft gage manometer. Gas velocity is given by VCgh LL ϭ 2 rr/ g where V = gas velocity C = pitot tube calibration coefficient. This would be 1.0 for an ideal pitot tube, but type S tubes deviate con- siderably. g = acceleration of gravity h L = liquid height differential in manometer ␳ L = density of manometer liquid ␳ g = gas density. It is necessary to measure the temperature and the pres- sure of the gas stream and estimate or measure its molecular weight in order to calculate density. Gas Analysis For precise work gas composition is needed for three reasons (1) so that molecular weight and gas density may be known for duct velocity calculations, (2) so that duct flow rates at duct condition can be converted to standard- ized conditions used for emission specifications. Standard conditions are usually 70°F, 29.91 in. mercury barometric pressure, moisture free basis with gas volume adjusted to TABLE 4 Required traverse points Code Duct sizes Number of points EPA 8 2 ft dia. 12 minimum More according to Figure 2 if near flow disturbance WP 17 <2 ft 2 >2–25 ft 2 25 ft 2 4 12 20 or more APCD 14 and ASTM 15 1–2 ft 2 (rectangular) 2–12 ft 2 >12 ft 2 1–2 ft dia. 2–4 ft 4–6 ft >6 ft 4 6–24 24 12 16 20 24 or more These numbers should be doubled where only 4–6 duct diameters of straight duct are upstream. ASME 16 <25 ft 2 >25 ft 2 8–12 12–20 Double or triple these numbers for high nonuniform flow. MINIMUM NUMBER OF TRAVERSE POINTS NUMBER OF DUCT DIAMETERS DOWNSTREAM* (DISTANCE B) DISTURBANCE SAMPLING DISTURBANCE *FROM POINT OF ANY TYPE OF DISTURBANCE (BEND, EXPANSION, CONTRACTION, ETC.) NUMBER OF DUCT DIAMETERS UPSTREAM* (DISTANCE A) SITE A B 23 4 5 6 7 8 9 10 0 10 20 30 40 50 0.5 1.0 1.5 2.0 2.5 FIGURE 5 Sampling points required in vicinity of flow distur- bance (EPA). TUBLING ADAPTER PIPE COUPLING STAINLESS STEEL TUBLING FIGURE 6 Type S Pitot tube for use in dusty gas stream. 12% CO 2 . Some codes differ from this, however. (3) For iso- kinetic sampling moisture content at stack conditions must be known in order to adjust for the fact that probe gas flow is measured in a dry gas meter at ambient conditions. C016_001_r03.indd 826C016_001_r03.indd 826 11/18/2005 1:15:35 PM11/18/2005 1:15:35 PM © 2006 by Taylor & Francis Group, LLC [...]... Griswold, S.S., W.H Parmelee, and L.H McEwen, Training of Air pollution Inspectors, 51st annual meeting APCA, Philadelphia, May 28, 1958 13 Conner, W.D and J.R Hodkinson (1967), Optical Properties and Visual Effects of Smoke-Stack Plumes, PHS Publication No 999-AP-30 14 Environmental Protection Agency, Standards of performance for new stationary sources, Code of Federal Regulations 40 CFR, Part 60 15 McKee,... Kingsbury, and J.G Cleland, “A Handbook of Key Federal Regulations and Criteria for Multimedia Environmental Control” prepared for U.S Environmental Protection Agency Research Triangle Institute, Research Triangle N.C 1979 3 National Center for Air Pollution Control (1968), A Compilation of Selected Air Pollution Emission Control Regulations and Ordinance, Public Health Service Publication No 999-AP-43 Washington... Friedrich, R and Reis, S (2004) “Emissions of Air Pollutants” Springer, Berlin 6 Katz, M ed “Methods of Air Sampling and Analysis” American Public Health Association, Washington, 1977 7 Powals, R.J., L.V Zaner, and K.F Sporck, “Handbook of Stack Sampling and Analysis” Technomic Pub Co Westport Ct., 1978 8 Brenchley, D.L., C.D Turley, and R.F Yarmak “Industrial Source Sampling Ann Arbor Science, Ann... collect smaller and smaller particles, and the size distribution of aspirated particles can be obtained from the weight collected on each stage and the size “cut point” calibration of the stage Several studies of calibrations have been published,3 3-3 7 and discrepancies have been pointed out.38 Impactors must be operated at constant known gas flow rate and for this reason are not capable of giving true... the long-normal distribution Commercial graph paper is available having one logarithmic scale and one cumulative normal probability scale If particle size is plotted vs cumulative percentage of sample at or below that size, the log-normal distribution gives a straight line A large percentage of emissions and ambient particulate distributions have log-normal distributions, and plotting on log-probability... sample train operation and on standard conditions for reporting emissions, and these are spelled out in detail in the specific test codes to be used Results are usually expressed both as grains per cubic foot (using standard conditions defined in the code) and as lbs/hr from the whole stack Measurement and Representation of Particle Size A determination of the emitted particle size and size distribution... is centrifugal sedimentation This is the standard test method of the Industrial Gas Cleaning Institute, and use of such devices of the Bahco type has been standardized by the ASME.32 The Bahco analyzer consists of a rapidly spinning rotor and a superimposed radial gas flow from circumference to center Larger particles are centrifuged to the outside diameter of the rotor, while small ones are carried... with the gas flow and by withdrawing gas so that velocity just within the tip of the probe equals that in the main gas stream Several recent studies29–31 have measured effects of probe size, alignment, and velocity on accuracy of sampling The sampled gas is drawn through a train of filters, impingers, and a gas meter by means of a pump or ejector Typical probes are shown in Figure 7, and several types... optically is about 0.5µ which is near the wavelength of visible light Electron microscopes may be used for sizing of smaller particles Counting is a laborious procedure, and sample counts are often small enough to cause statistical errors at the very small and very large ends of the distribution This method requires the smallest sample size and is capable of giving satisfactory results Care must be taken... sampling time or volume is often set by regulation Examples are: Bay area24—Sample gas volume = 20 L0.8, where volume is in standard cubic ft, and L is duct equivalent dia in ft A maximum sampling rate of 3 SCFM is specified and a minimum time of 30 min ASME27—Minimum of 2hr with at least 10 min at each traverse point through two complete circuits APCD25—5–10 min/point for a total run of at least 1 hr Industrial . as a function of duct area or diameter. Representative requirements are shown in Table 4. S-6 S-5 S-4 E-4E-5E-6 E-3 E-2 E-1 EAST S-3 S-2 S-1 SOUTH R 3 R 2 R 1 FIGURE 4 Velocity and sampling. and Visual Effects of Smoke-Stack Plumes, PHS Publication No. 999-AP-30. 14. Environmental Protection Agency, Standards of performance for new stationary sources, Code of Federal Regulations. concentrations and sources of air pollutants. The following paragraphs give an overview of standards for ambient particulate pollution and source emission. The precise and practical methodology of making