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OAR Box 1313 

Prepped by LaTeia Shed 

Document Number: 

67) ll-B-41 

Docket Number: 

A-88-02 

Printed 6/12/2008 9:03:30 AM Sheet 67 of 99 
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MRI® MIDWEST RESEARCH INSTITUTE 

Suite CT 

A-88-0 2 "01 Harnso n 0ak s Bouievar, 

Carv. NC. 27? 1 

Date: May 20, 1988 

(Finalized June 30, 1988) 

Subject: Site Visit—Saco Defense Inc., Saco, Maine 

Chromium Electroplating NESHAP 

EPA Contract 68-02-3817; ESD Project 85/02a 

MRI Project 7717-K 

From: Randy Strait 

To: Andrew Smith 

ESD/ISB/SSS (MD-13) 

U. S. Environmental Protection Agency 

Research Triangle Park, N.C. 27711 

I. Purpose 

The purpose of this site visit was to evaluate the operating 

condition of the single packed-bed horizontal-flow scrubber used to 

control chromium emissions from three hard chromium plating tanks. The 

scrubber is being evaluated as a candidate for conducting emission tests 

to determine the extent to which cleaning the scrubber can improve 

scrubber performance. 

II. Place and Date 

Saco Defense Inc. 

291 North Street 

Saco, Maine 04072 

March 31, 1988 

(207) 283-3611 

III. Attendees 

Saco Defense Inc. 

Robert Noonan, Senior Environmental Engineer 

Duall Industries, Inc. 

Ron DeFrenn, Field Representative 

Midwest Research Institute 

Randy Strait 

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IV. Discussion 

In March 1988, plant personnel hired an industrial hygiene 

consultant to evaluate the ventilation rates on three hard chromium 

plating tanks (identified as Tanks 22, 23, and 24) that are controlled by 

the single packed-bed scrubber being evaluated for testing. The combined 

de|ign airflow rate for the three tanks is3340 cubic meters per minute 

(m /min) (12,000 cubic feet per minute [ft /min]), or 113 m /min 

(4,000 ft /min) for each tank. The surface area of each tank is 

1.5 square meters (16 square feet). Therefore, the3design2ventilat1gn 

rate for each tank js 76 m ,/nrin per square meter (m /min/m ) (250 ft/min 

per square foot [ft /min/ft ]) of tank surface area. Results of the 

ventilation stydy indicated that the actual ventilation rate for each tank 

was about 4| m /min/m (16^ ft /min/ft ) and the actual airflow rate was 

about 70 ft /min (2,560 ft /min). Plant personnel indicated that the low 

ventilation rates for the tanks may be caused by a makeup air deficit in 

the plant and/or a decrease in the operating performance of the scrubber 

fan. Therefore, plant personnel requested Duall Industries, Inc., to 

inspect the scrubber to determine if the scrubber was operating at its 

design specifications. 

Mr. Ron DeFrenn, Field Representative for Duall Industries, Inc., 

(Duall) measured the airflow rate to the scrubber and visually inspected 

the packed bed, packing media, water recirculation system, mist 

eliminator, and fan of the scrubber to determine whether the scrubber was 

operating according to design specifications. This report summarizes the 

results of Mr. DeFrenn's evaluation of the scrubber. 

V. Results 

A. Airflow Rate 

The3scrubber is designed for an airflow rate^ of 340 cubic meters per 

minute (m /min) (12,000 cubic feet per minute [ft /min]). A pitot tube 

was used to take a velocity traverse in the ductwork at the inlet of the 

scrubber. The ductwork is 0.61 m (2.0 ft) in diameter. Because plant 

personnel indicated that the plant was experiencing a makeup air deficit, 

a velocity traverse was taken with the doors in the plant closed and 

another traverse was taken with the doors in the plant opened. The 

airflow velocity and airflow rate measured with the plant doors closed was 

634 meters per minut| (m/min) (2,080 feet per minute [ft/min]) and 

184 m /min (6,500 ft /min), respectively. The airflow velocity and 

airflow rate measured with the plant doors opened was 670 m/min 

(2,200 ft/min) and 198 m /min (7,000 ft /min), respectively. 

B. Packed Bed 

The packed bed is 0.3 m (1.0 ft) in depth, 1.6 m (5.3 ft) in height, 

and 1.7 m (5.5 ft) in width. The design face velocity of the airflow 

through the packed bed is 125 m/min (410 ft/min). The frame of the packed 

bed is warped. Both sides of the frame are buckled outward which has 

allowed the packing media to settle, leaving about 0.46 m (1.5 ft) of 
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space between the top of the scrubber and the packing media. 

Consequently, the contaminated air passes over the top of the packing 

media. Warping of the packed-bed frame typically occurs when the strands 

of polypropylene that tie the walls of the packed bed together break as a 

result of wear. 

C. Packing Media 

The packing media used in the packed bed was manufactured by 

Protak. The packing media is made of polypropylene and consists of three 

concentric rings that form a sphere. Each sphere is 6.35 centimeters 

(2.5 inches) in diameter. The packing media §as3a surface area-to-volume 

ratio of 128 square meters per cubic meter (m /m ) (39 square feet per 

cubic foot [ft /ft ]) and a void space of 90.6 percent. Mr. DeFrenn 

indicated that the packing media is very dirty. A thin layer of chromic 

acid residue has accumulated on the surface of the packing media. 

Although this type of packing media no longer is manufactured, the surface 

area-to-volume ratio and percent void space is similar to that for the 

Glitch ballast rings currently used bv Dyall. G]itc^ ballast rings have a 

surface area-to-volume ratio of 144 m /m (44 ft /ft ) and a void space of 

91 percent. 

D. Water Recirculation System 

The scrubber was designed with a self-contained recirculation 

system. Four spray nozzles are located at the inlet of the scrubber 

upstream of the packed bed. Four spray nozzles also are located over the 

top of the packed bed to allow for continuous flooding of the packing 

media. The design water flow rate to the scrubber is 132 liters per 

minute (35 gallons per minute). 

Currently, the self-contained water recirculation system is 

disconnected. Water is supplied to the scrubber from a rinse tank located 

ne<t to the chromium plating tanks. The scrubber water is pumped from the 

rinse tank, through the spray nozzles, and then drained back to the rinse 

tank. The water line to the scrubber also is used to supply water to a 

second scrubber. The water pump is located next to the rinse tank. The 

rinse tank is the last of three rinse tanks used in a countercurrent rinse 

system. The chromic acid concentration of the rinse water that is pumped 

to the scrubber is 1.1 grams per liter (0.15 ounce per gallon). 

Three of four spray nozzles at the inlet of the scrubber are 

partially plugged and one nozzle is broken off of the spray header. No 

water is supplied to the four spray nozzles located over the top of the 

packed bed. 

E. Mist Eliminator 

A chevron-blade mist eliminator with a single set of overlappingtype blades is located downstream of the packed bed. The mist eliminator 

is 0.20 m (0.67 ft) in depth, 1.6 m (5.3 ft) in height, and 1.6 m (5.3 ft) 

in width. The design face velocity of the airflow through the mist 

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eliminator is 130 m/min (430 ft/min). The structural integrity of the 

mist eliminator appeared to be sound. None of the blades had collapsed. 

However, there is some buildup of chromic acid residue on the blades. 

F. Fan 

The fan (Serial No. 5615) is designed to pull 340 m3/nrin 

(12,000 ft /min) of air. It is a Type NH blower, Class II, Size 99, with 

a static pressure of 1.0 kilopascals (4.0 inches of water column). The 

design specifications of the fan motor (Serial No. 556591) are 15 horsepower, 1,750 revolutions per minute, 40/20 amperes, 230/160 volts, and 

60 cycles. 

The fan wheel is unbalanced and the fan belts need to be replaced. 

The fan wheel is coated with chromic acid residue as a result of the 

contaminated air bypassing the packing media. A crack in the fan housing 

also will need to be repaired. 

VI. Conclusions 

Results of the evaluation indicate that the scrubber is in poor 

operating condition and should not be tested until the scrubber has been 

reconditioned to operate at design specifications. The low airflow rate 

to the scrubber probably is caused by the poor operating condition of the 

fan rather than a makeup air deficit in the plant because the difference 

in the airflow rate to the |crubber with3the plant doors closed and the 

plant doors opened was 14 m /min (500 ft /min). Duall recommends the 

following repairs to the scrubber before testing: 

1. The fan wheel should be cleaned and balanced, fan belts 

replaced, bearings greased, and the crack in the fan housing repaired to 

ensure that the scrubber is operated at the design airflow rate; 

2. The packed-bed frame should be restored such that its structural 

integrity and dimensions meet design specifications; 

3. The remote water recirculation system for the scrubber should be 

disconnected and the self-contained recirculation system should be 

reconnected to ensure that all spray nozzles located at the inlet of the 

scrubber and over the packed bed are adequately supplied with water; and 

4. New spray headers and spray nozzles should be installed to 

ensure that the scrubber is operated at the design water flow rate. 

The cost of reconditioning the scrubber will be about $4,000. After 

the scrubber has been restored to its design operating condition, the 

scrubber can be tested before and after the scrubber is cleaned to 

determine if cleaning can improve scrubber performance. Cleaning of the 

scrubber will involve washing all chromic acid buildup from the surface of 

the packing media, inside walls, and mist elimination section of the 

scrubber. Plant personnel are restoring the scrubber to its design 

operating specifications and will assist in the cleaning of the 

scrubber. 

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