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OAR Box UIO 

Prepped by Ryan Dugan 

Document Number: 

2) IV-B-1 

Docket Number: 

A-82-39 

Printed 4/14/2008 1:23:55 PM Sheet 2 of 156 
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%r ** 

i 

* l PRO* 0 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY / |/-~S^ / 

Office of Air Quality Planning and Standards 

Research Triangle Park, North Carolina 27711 

20 M t«* 

MEMORANDUM 

SUBJECT: Requirement of Continuous Opacity Monitors (COM's) in the 

Caleiner and Dryer New Source Performance Standards (NSPS) 

FROM: Bil l Harnett iAuirHdAiY^i H IW/TMUV\" C ^ U ^O ^ 

Standards Preparation Section, SDB (MD-13) ?ctr*>\-^° 

TO: Doug Bell , Chief ^ \9% 

Standards Preparation Section , SDB (MD-13) ^$> \ 

r.\ 

c

r

-

INTRODUCTION 

On April 23, 1986, the New Source Performance Standard for Calciners 

and Dryers in Mineral Industries was proposed in the Federal Register 

(51 FR 15438). To ensure proper operation and maintenance of the control 

devices, one aspect of the standard requires the use of COM's by most of 

the industries affected. During the public comment period, several 

industries commented that the increased capital and operating costs 

associated with continuous opacity monitoring are not commensurate with 

the benefits. As a result of these comments, the COM requirements have 

been reexamined for all industries. This memorandun disucssed the assumptions and analyses associated with this reexamination. 

BACKGROUND 

The proposed standard states that new, modified, and reconstructed 

calciners and dryers meet emission levels of 0.04 gr/dscf and 0.025 gr/dscf 

respectively. The control devices that can be used to meet the emission 

limits are electrostatic precipitators, baghouses, and wet scrubbers. 

As proposed, owners or operators of affected facilities which use 

electrostatic precipitators (ESP's) and baghouses (3H's) to comply with 

the standards would be required to install COM's to neasure and record the 

opacity of emissions from the control device. For scrubbers, pressure 

drop and liquid flow rate monitoring devices were required. Ue received 

no negative comments concerning the monitoring requirements for scrubbers 

and their requirements will remain the same. 

Development of the proposed COM provisions was based on the following 

analysis and assumptions: First, as a matter of policy and past experience, 

we assume that COM's are useful and beneficial and should be required in 
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cases where the cost is reasonable. The utility and benefits derive both 

from EPA's enhanced enforcement ability and from industries ability to better 

maintain control systems when emission data are available. The reasonableness of the cost impact of the standard was evaluated using a criterion 

of cost effectiveness less than or equal to $3,000/Mg ($2,700/ton) of 

particulate matter (PM) removed. 

At proposal, to calculate the cost effectiveness (CE) of installing 

and operating a COM, the annual operating cost of the COM was added to 

the incremental annual operating cost of the PM control device and then 

divided by the incremental emission reduction achieved by the control 

device above baseline (See Attachment 1 for example). With the exception 

of the four process units listed below, all of the cost effectiveness 

values were less than or equal to $3,000/Mg. 

The four process units that failed to meet this criterion were: 

1. Gypsum flash calciners 

2. Gypsum kettle calciners 

3. Perlite rotary dryers 

4. Perlite expansion furnaces 

The proposed standard allows weekly visible emission readings as an 

alternative to a COM for these process units. 

The COM requirements resulting from the analysis described above 

prompted comments from several industries, including Alumina, Ball Clay, 

Fire Clay, Kaolin, and Lightweight Aggregate. The comments generally 

stated that the costs of monitoring devices are excessive and that the 

benefits, if any, are small and do not offset the costs. As a result 

of these comments, the basis of the proposed COM requirements has been 

reevaluated and alternative decision criteria have been investigated. 

The next sections presents the results of this work and a recommendation 

on how to proceed. 

ANALYSIS 

Several commenters on the proposed COM requirements stated that broken 

bags in a collector are apparent without the need for a COM and the increased 

capital and operating costs associated with COM's do not produce emission 

reduction benefits. These commenters felt that this requirement should 

only apply to major sources of pollution. 

It is true that a sudden increase in emissions Trom a BH or ESP would 

indicate a sudden failure of the control device which would require immediate 

attention by the source operator. However, the purpose of a COM or other 

monitoring alternatives such as daily visible emissions observations is to 

alert the operator to the need for maintenance to correct causes of more 

.* ' * ' 
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subtle and gradual deterioration of the control device efficiency that 

occurs over time. Without COM's, operators have essentially no tools that 

they can use to properly set up or optimize ESP's or fabric filter systems, 

or to assume that necessary maintenance is performed. The ESP rapping 

cycles, fabric filter cleaning cycles, broken rapper welds and bag deterioration are examples of items that effect emissions and that cannot be 

evaluated or detected except with COM's (See Attachment 3). These items 

do not show up as catastrophic failures. Because the material collectedby the control equipment is a saleable product in a number of the industries 

covered by this NSPS, the COM has the benefit of saving money as well as 

preventing pollution. The reporting of excursions as recorded by COM's 

also helps State and local enforcement programs identify sources which 

are having repeated maintenance problems with their control devices. 

However, as the amount of emissions from an individual source decrease," 

the benefits of monitoring also decrease and at some point it is no 

longer reasonable to require a COM or other monitoring alternative. In 

fact, in the extreme case of a small fabric filter system on a transfer 

point, the cost of a COM could exceed the fabric filter cost but because 

of the small emission benefit possible as a result of improved maintenance, 

the potential benefit of the COM would be small. 

An alternative approach to assessing the reasonableness of the monitoring 

requirements based only on the cost effectiveness of the control device and 

the monitoring alternative as was done at proposal would be to consider 

other factors in addition to cost effectiveness such as the significance of 

the source's emissions and the other benefits of monitoring requirements 

as discussed above. 

The Agency has previously addressed the significance of an emission 

source's potential to emit PM in the development of the prevention of 

significant deterioration (PSD) of air quality program. In the PSD rules, 

the Agency set de minimis levels of emissions for various pollutants. 

For PM emissions, the level was selected by evaluating the potential 

effect of different emissions levels on an area's air quality and how 

that related to the national ambient air quality standard for PM. -Ulg ^ 

anal y_siijd^wa.s_.bA5.ed_jpi! ...a _.s ou rx eis _p.ot en.tj.al~to„em.i„t_a.f_teii-a p pli catiojupjC 

TlT~ap'prbpriAte.J.ederal__reg The significance level 

""for' PM emissions was set at 22.7 Mg/yr (25 Tons/yr). This cutoff could 

be considered in determining which facilities should be required to 

install COM's if they use dry control devices. 

For calciners and dryers with emissions of less than 22.7 Mg/yr 

after NSPS controls, four monitoring alternatives were evaluated: 

(1) installation of a COM; (2) daily visible emissions observations; (3) 

weekly visible emissions observations; and (4) no monitoring requirements. 

After consideration of the costs and other benefits associated with a 

COM, it appears to be unreasonable to require COM's on the smaller emission 

sources (i.e., controlled emissions < 22.7Mg/yr). 

In lieu of COM's, we also reassessed the reasonableness of performing 

daily versus weekly visible emission observations. We determined that the 

cost of either would be similar but would not deliver the same benefits as 
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the COM's. In both cases, employees of the affected plant would need to 

be formally -certified as opacity readers twice per year. The costs 

associated with the certification would be incurred regardless of whether 

a daily or weekly monitoring requirement was imposed. The other costs 

associated with these alternatives are the annual cost of performing the 

observations and recording the results. The annual cost of weekly readings 

of visible emissions would be reduced somewhat, but because of the fixed 

cost of certification, would cost approximately 40 percent of the cost of 

doing daily observations. Moreover, a daily observation program would be 

more effective at identifying gradual deterioration of the control device 

efficiency and allowing a plant operator time to correct the problem 

prior to a complete failure of the device. A weekly observation program 

would not identify the gradual deterioration of the control device as 

quickly and, in some cases, a failure of the control device could occur 

between two weekly observations. Because requiring daily observations 

would yield substantially greater benefits than weekly observations and 

the cost difference was considered reasonable, the alternative of weekly 

observations was considered inferior for the sources with less than 22.7 

Mg/yr of emissions after NSPS control. 

As is the case with COM's, the cost of doing daily visible emission 

observations does not change with the size of the source or the control 

device. Thus, for very small sources with small control devices, the cost 

associated with daily visible emission observations can be a significant 

portion of the annualized cost of operating and maintaining the control 

equipment even though the benefits in terms of reducing excess emissions 

have decreased. At some point, visible emission monitoring requirements 

are no longer reasonable because the benefits are small but the cost of 

monitoring has substantially increased as a percent of the annualized 

cost of the control equipment. 

To determine the exact size of a source where monitoring requirements 

are no longer reasonable is more a function of judgment than analysis. 

While the costs can be estimated with reasonable certainty the actual 

reduction in excess emissions that would occur is much more uncertain. 

Consideration was given to the magnitude of the cost of daily visible 

emission observations as a percent of the annualized cost of operating 

the control equipment, the size of the source in terms of the emissions 

after NSPS control is applied, and the benefits associated with monitoring 

requirements such as identifying sources who are having control equipment 

problems for the appropriate enforcement agency so corrective action can 

be taken. Based on a consideration of all these items, we conclude it js 

unreasonable to require sources with less than 10 Mg/yr of particulate 

emissions after NSPS control to perform daily visible emission observations. 

The cost of the daily observations for the most of these small sources is 

more than 10 percent of the annualized cost of operating and maintaining 

the control device. In addition, the potential benefits in terms of 

reduced episodes of excess emissions would be much smaller for these 

sources than for the larger sources. 

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RECOMMENDATIONS 

Because of the variation in emissions after NSPS control for each size 

and type of caleiner or dryer and for each industry, the monitoring 

requirements should be based on the typical size of a particular type of 

calciner or dryer in each industry. Table 1 shows the NSPS level of 

emissions for each type and size of calciner and dryer in each industry 

and which sizes are typical (see Attachment 2). 

It is recommended that COM's be required on all dryers or calciners 

within an industry where the typical size unit has emissions after NSPS 

control equal to or above 22.7 Mg/yr. For those typical units with emissions 

less than 22.7 Mg/yr but greater than or equal to 10 Mg/yr, it is recommended 

that these sources be required to perform daily visible emission observations. 

For those industry categories where the typical size unit emits less than 

10 Mg/yr, it is recommended that no monitoring requirements be placed on 

these units. Table 1 contains a summary of the recommendations for each 

type of dryer and calciner in each industry (see Attachment 2) . 

Attachments 
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Attachment 1 

The annual cost effectiveness of control obtained by meeting NSPS 

level of emissions: 

Cost of transmissometer + Improved operations and 

maintenance cost of control device 

C/E = Incremental Emission reduction 

Example: Ball clay industry which uses a vibrating grate dryer 

process unit 

$10,688* + $5,000 

C/E = 31 tons/yr - $506/ton 

*Note: Since these calculations were made, the labor rate has 

increased and the annual cost of a continuous opacity 

monitor is now $12,800. 7...Y 

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P.8 

' , ATTACHMENT 2 

TABLE 1. NSPS EMISSIONS AND MONITORING RECOMMENDATIONS 

Industry 

Alumina 

Ball Clay 

Bentonite 

Diatomite 

Feldspar 

Fire Clay 

Fuller's 

Earth 

Gypsun 

Industrial 

Sand 

Process Unit 

Flash Calciner 

Rotary Calciner 

Rotary Dryer 

Vibrating Grate Dryer 

Fluid Bed Dryer 

Rotary Dryer 

Flash Dryer 

Rotary Dryer 

Rotary Calciner 

Fluid Bed Dryer 

Rotary Dryer 

Rotary Dryer 

Vibrating Grate Dryer 

Rotary Calciner 

Fluid Bed Dryer 

Rotary Dryer 

Rotary Calciner 

Rotary Dryer 

Flash Calciner 

Kettle Calciner 

Fluid Bed Dryer 

Rotary Dryer 

Design NSPS Emissions (Mg/Yr) 

for various sized plants 

S 

-

T74 

-

-

-

10 

T12 

-

11 

-

-

7 

-

15 

-

T8 

9 

-

-

-

9 

T7 

M 

-

91 

Tg 

Tl5 

T"27 

•

 T l4 

-

T8 

- • 

T5 

8 

TlO 

T33 

T25 

-

12 

T23 

T7 

T2 

Tl 

Tl8 

12 

L 

T87 

113 

-

30 

-

24 

21 

-

T22 

Tg 

T l 3 • 

14 

-

-

T63 

18 

30 

9' 

-

-

42 

21 

i 

Recommendation 

COM 

COM 

No Monitoring 

Daily V.E.'s 

COM 

Daily V.E.'s 

Daily V.E.'s 

No Monitoring 

Daily V.E.'s 

No Monitoring 

Daily V.E.'s 

Daily V.E.'s 

COM 

COM 

COM 

No Monitoring 

COM 

No Monitoring 

No Monitoring 

No Monitoring 

Daily V.E.'s 

No Monitoring 
P.9 

, 

Industry 

Kaolin 

Lightweight 

Aggregate 

Magnesium 

Compounds 

Perlite 

Roofing 

Granules 

Talc 

Titanium 

Dioxide 

Vermiculite 

•if 

T = Typical si 

Daily V.E.'s = 

ATTACHMENT 2 (continued) 

Process Unit 

Rotary Dryer 

Spray Dryer 

Flash Calciner 

Multiple Hearth 

Furnace 

Rotary Calciner 

Rotary Calciner 

Multiple Hearth 

Furnace 

Rotary Calciner 

Rotary Dryer 

Expansion 

Furnace 

Fluid Bed Dryer 

Rotary Dryer 

Flash Dryer 

Rotary Dryer 

Rotary Calciner 

Flash Dryer 

Fluid Bed Dryer 

Rotary Dryer 

Rotary Dryer 

(Indi rect) 

Spray Dryer 

Rotary Calciner 

Fluid Bed Dryer 

Rotary Dryer 

Expansion Furnace 

Design NSPS Emissic 

for various sized 

S 

-

-

T26 

T7 

Tl8 

34 

11 

T30 

-

T4 

Tl4 

T4 

-

Tl5 

-

1 

-

6 

27 

-

-

T4 

1 

M 

T9 

Tlfi 

-

-

-

T49 

T35 

43 

Tl5 

-

Tl3 

T22 

-

T5 

-

; 

3 

Tl 

Tl5 

T53 

-

Tn 

1 

ze; - = Data is not available; COM = Con 

Daily visible emission observation 

HIS (Mg/Yr) 

plants 

L 

-

T26 

-

-

-

66 

T49 

-

25^ 

-

29 

-

19 

-

T 28 

Tl8 

T7 

-

24 

-

Tl9 

12 

-

tinuous Opa< 

Recommendation 

No Monitoring 

COM 

COM 

No Monitoring 

Daily V.E.'s 

COM 

COM 

COM 

Daily V.E.'s 

No- Monitoring 

Daily V.E.'s 

Daily V.E.'s 

No. Monitoring 

No Monitoring 

Daily V.E.'s 

COM 

Daily V.E.'s 

Nd Monitoring 

No Monitoring 

Daily V.E.'s 

COM 

Daily V.E.'s 

Daily V.E.'s 

No Monitoring 

:ity Monitor; 
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ATTACHMENT 3 

PUUWNG 

Opacity monitoring of stack emissions: 

A design tool with promising results 

Reprintedfrom the electric utility . . . GENERATION PLANBOOK 1974 

(By the editors of Power magazine) Copyright McGraw-Hill, 1974 
P.11 

Montour Station, which went on line last 

fall with two 800-MW coal lired units, was 

the scene of PP&L's opacity-monitoring 

installation and revealing tests 

Opacity monitor is placed close to 

precipitator outlets. Savings in time and 

cost show that breeching and duct in time and 

cost show that breeching and ductwork 

are the most satisfactory locations 

Opacity monitoring of stack emissions: 

A design tool with promising results 

How can the designer make plans for evaluating performance of an electrostatic 

precipitator? Is it at all possible to 'tune' a precipitator for optimum 

performance? At least one utility believes they have found a feasible method 

of optimizing precipitator performance through continuous opacity readings 

By W A Schneider, Plant Betterment Field Assistant, Pennsylvania Power & Light Co 

Gauging precipitator performance in years past was 

generally a job of physical test for efficiency, or for outlet grain loading. This scheme, at best, provided an average figure related to several hours of operation. Dust 

testing calls for several men and considerable time to 

yield this information. Yet through real-time observation of the effects of precipitator control changes, fuel 

changes, and changes in boiler operating conditions on 

outlet dust loading—all through use of continuous opacity monitoring-a reasonable appraisal of performance 

can be made. And from an operating standpoint, should 

an existing precipitator fall short on collection ability, 

opacity monitoring will open the door to available alternative*. 

The alternatives open to the designcr-and postdesigner—are many. The search then boils down to a 

practical means for accurately evaluating these alternatives. In brief, the possible alternate paths encompass 

optimization of .existing precipitator . . . updating . . . 

modifying boiler operating conditions . . . changing flue 

gas resistivity. . ^bringing in additional collection equipment. It was the^earch through these alternatives that 

led to the opacity monitor. 

Opacity monitor consists of a light source, and a 

photocell arranged so the light must pass through the 

gas stream prior to being measured by the photocell. 

Change in light absorption caused by particulates in the 

gas is a measure ofthe quantity of dust passing between 

source and photocell. 

We weren't into our opacity-testing program long 

when we found the value in detecting effects of individual rappers, or smalt changes in precipitator power levels, as being most important in evaluating and optimizing performance. In the Lcar-Siegler RM-4 opacitytesting equipment we used, the photocell and light 

source are located in the same housing on one side of 

the gas stream, with a reflector on the other. This means 

that the light-path lengtii is at least double the width of 

the gas passage, enhancing the monitor's sensitivity. 

Selection ofthe system was based on its use of visible 

wavelengths, since accuracy of detecting submicron particles is poor with infrared. Moreover, it outputs a signal 

for optical density. As this is proportional to outlet grain 

loading, it provides a valuable feature when combined 

with high sensitivity. 

Accuracy played a major role in our monitor selection. One factor was the monitor's design feature of a 

single location for both light source and detector. This 

feature means that the unit can be checked in service 

for zero and span calibration, ln effect, it automatically 
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U^im 

Cow voltage, 

tittle sparking, 

large rapping effects 

Medium voltage, 

moderate sparking, 

small rapping effects 

High voltage, 

heavy sparking, 

moderate rapping effects 

Effects of 

voltags control changes 

at constant 

rapping Intensity 

100 

Optical-density record shows interaction between precipitator voltage and rapping 

intensity. Two monitors were used for increased detection of performance changes 

4 0 60 

Opacity, % 

i i i I i__i I I i I I 

100 60 6Q 40 20 0 

Tra«smlttoii««,*/* 

Relationship between optical density as 

measured and opacity or transmittance 

checks and outputs zero and span values periodically. 

Adjustments can be made for dust buildup on the windows, or because of bulb-intensity decay, while the instrument is on line. 

Before developing and using opacity-monitoring 

equipment, two program steps must be considered. First 

is examination of the precipitator maintenance and operation data. The second is to combine these data with 

an inspection by the manufacturer. Early identification 

of problems— particularly in alignment stabilization, 

leakage, gas distribution—can be of considerable value. 

We found that such small but important modifications 

contributed immensely to improved reliability. 

Next move brings the opacity-monitoring equipment 

fc into the act. As in any dust test, you must identify and 

control all variables known to affect precipitator performance. In our evaluation, we found the following 

most significant: Fuel resistivity and ash content; boiler 

load: boiler outlet-gas temperature; boiler excess-air 

l=-d. precipitator operating voltage; precipitator rappi.-.2 intensity and programming; and precipitator internal conditions. Each of these areas can be studied with 

opacity-monitoring equipment. The designer should 

bear in mind that the determination of the "proportionality constant" between optical density and outlet 

grain loading can be determined through dust testing 

under constant boiler and precipitator conditions with 

various fuels. 

There will be some overlapping or interaction of variables. Example: precipitator voltage and rapping at different fuel sulfur levels. It is our experience that fuel 

sulfur content is the one variable where there can be 

little practical control. Thus, all other controllable variables must,be examined with respect to the fuel's sulfur 

content. After a brief investigation of the sulfur content 

in the fuel burned, we found that—depending on the 

ran He of sulfur content—it was possible to select several 

subdivisions for describing the effect of each variable at 

various sulfur levels: low sulfur (less than 2%), medium 

sulfur (2-3%), and high sulfur (above 3%). 

Fuel resistivity, which is inversely related to fuel sulfur content, is a base for evaluation of all other variables. It is valuable lo define the effect of each variable 

with respect to fuel sulfur, since estimates of percent of 

fuel burned in each range should be available in defining the required use of each alternative. A case in point: 

the estimated requirement of a gas-conditioning agent. 

Since fuel-sulfur increases represent a simulation of 

conditioning, the fuel sulfur required to meet regulation 

can be correlated with conditioning-agent quantity requirements. 

By holding all other variables constant, a curve of 

fuel sulfur vs outlet grain loading was developed. Results indicate that, for most coals below 2% sulfur, we 

did not meet our emission standards. Therefore, conditioning agent is injected to match the resistivity of 27csulfur fuel. 

The special study of sulfur or resistivity effects also 

provides the most helpful information if additional collection equipment should be required. If high resistivity 

is the major problem, the baghouse or particulate scrubber is the more logical approach. Conversely, if high ash 

levels at low resistivity are overloading the existing precipitator, the problems of acid smut or slurry pH may 

eliminate the baghouse or scrubber. 

Boiler load. Of primary importance here is the reduction of load necessary for compliance with federal or 

local particulate-emission legislation. As the monitor 

gives a signal proportional to outlet grain loading, this 

output can be correlated to the emission rate in pounds 

per million Btu. One must be careful, however, to realize that the proportionality factor between Ib/cu ft and 

lb/MBtu depends on the boiler operating conditions 

and load. 

We feel that the determination of the load reduction 

required for compliance is valuable only in emergency 
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^* i\ix 

h^w r* 

Monitor ductwork location can ease Installation 

0.9 

0.8 

0.7 

0.6 

| 0.5 

I 0.4 

I 0.3 

S 0.2 

0.1 

^&\ I I 1—: 1 

: 0.05 0.10 0.15 0.20 0.25 0.30 0.35 

Groins/cu ft 

Testdc'.a relate optical density to outlet grain loading 

1 

-

-

~ 

1 

j-«—AllowoUe emission rate 

l 

l 

I 

I 

I 

I 

i 

I 

l 

\P 

<aP, , 

%^s 

i i 

y^o 

• 

<^ o 

I 

0.05 0.10 0.15 0.20 0.25 0.30 0.35 

Grolns/cu ft 

Fuel s•.•"ur vs grain loading, other variables constant 

situa:' .*ns. prior to the time that continuous compliance 

is ach.-:ved. 

A> ;as temperatures in a cold-end precipitator are 

drop:..! below 320 F. precipitator performance improve It is the magnitude of this increase, plus the anlicipa-.-.-d utilization, which would then be weighed 

agair. •. probable increased maintenance costs. 

Excess air. With lowered excess-air levels, gas velocities *• ithin the precipitator will be lowered, again resuhir.. in increased collection. Although not nearly so 

feas:'-.••-• as lowering outlet-gas temperature, this could 

be \-<-7. in emergency. The tradeoff of increased collection \ - boiler reliability is nearly identical lo the altern..*. . e of outlet-gas temperature reduction. 

Precipitator operating voltage. Our experience 

shov- this to be an area where much information can 

be realized. By adjusting the controls and observing 

their effects directly on the monitor output, the best 

manual operating mode can be established for each fuel 

sulfur level. After this manual adjustment, precipitator 

performance can be compared to the normal automatic 

operating mode ofthe controller for evaluation. 

Magnitude of the increased collection gained through 

the manual optimization adjustment will be a determining factor as to whether new or improved controls or redistribution of power should be considered. We observed a decrease in optical density resulting from small 

changes in control setpoints. 

It is important to recognize at this time that voltage 

levels, rapping and particle resistivity (related to fuel 

sulfur level) are all interacting variables. The approach 

to their study must include different combinations until 

the "optimum" is discovered. This is not an overnight 

process; it is greatly simplified, however, because ofthe 

real-time output of the effects of each change by opacity-monitoring equipment. 

Precipitator rapping. The opacity monitor is sensitive enough to detect individual rappers, and therefore 

to locate the problem areas specifically. The effects of 

rapping, basically on dust thickness on the plates and 

on re-entrainment, are observed by changes in overall 

optical density level and spikes. Unfortunately, the current technology of precipitator design does not include 

self-adjusting rappers, and therefore one might consider 

daily "tuning" based on outlet loading as an alternative 

for continuous increased performance. 

Internal condition. From a study of the effects of 

•each of the above, certain areas of the precipitator may 

seem to respond much better than others in attaining 

defined "optimum" operating conditions. This is a 

strong indication of internal physical difficulties. If this 

indication is further supported by maintenance records 

or the manufacturers' inspection comments, the indication ofa problem is further strengthened. 

The key to obtaining useful information for designer 

and operator, from a series of tests as described here, is 

to hold all parameters other than that being investigated as nearly constant and close to representative operating conditions as possible. If this is done, a highly 

detailed and informative picture of the performance of 

your precipitator and the feasibility of your alternatives 

can be obtained in roughly one month's time. 

If evaluated carefully, the following questions can be 

accurately answered: Can I meet my emission standard 

with my existing precipitator? Is there a modification of 

controls or rappers that will allow me to comply? Are 

changes in boiler conditions or reduction of load feasible solutions? Can flue-gas conditioning solve my 

problem? How much additional collection capability do 

I need, and what type will solve my problem? 

The burden of meeting specific particulate-emission 

regulations by"-1975 is a large one. The investment of 

time and money will also be large. We at PP&L feel, 

however, that accurate evaluation of the problem, including the existing precipitator, is a most important 

first step. The use of opacity-monitoring equipment has 

enabled us to develop a program that can be quickly 

administered, and can provide accurate answers to 

many ofthe questions inherent in the selection of the 

best alternative for increasing dust collection. •