EQUIPMENT
BUILD A MODEL. Three-dimensional models show operation of electrostatic precipitators. This model helped determine flue design for a unit being added to existing equipment
GET PERFORMANCE DATA. D a t a from models aid design of new equipment. Here, effects on gas flow are studied by making a velocity traverse across the precipitator plates
Models Create N e w Sales A p p r o a c h Transparent models throw light on precipitator design problems, point w a y to lower cost JYlODELS HAVE COME OF AGE in the electrostatic precipitator field. And, this aging might mean dollars to companies that plan to install gas or smoke cleaning systems in their plants. With transparent models, ResearchCottrell takes a three-dimensional look at design and operating characteristics of electrostatic precipitators and auxiliary equipment. These scaled miniatures correlate directly with full-scale units. T h e results, then, point the way to better designs and, in turn, to lower construction and operating costs of plant units, says R-C. • N e w Sales Approach. ResearchCottrell points out the models also 102
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mean a n e w approach to electrostatic precipitator sales. Before, these units were sold on a "flange-to-flange" basis. Consequently, R-C explains, the p r e cipitator maker would submit a bid based on a unit designed t o fill the space available. He had little, if anything, to say about flues before or after the precipitator. Nor did t h e precipitator maker h a v e any say about blowers or other parts of the gas cleaning system. Each p a r t manufacturer would design a unit to take u p as little space as possible. His bid was often based on equipment which had short ducts and sharp, right angle turns, comments R-C.
B u t models may change bid practices. R-C figured flue design w a s very important to a precipitator's efficiency. T o prove it they t u r n e d to scaled working models. Company research workers could then watch and study gas flow patterns and also measure velocity and pressure changes. Titanium tetrachlor i d e "smoke" was used as the gas in t h e s e studies. Now the model studies can mean dollar savings to industry. For example, the greater the pressure drop through the flues, the larger t h e fan a n d m o t o r must b e to draw the gas t h r o u g h t h e system. E a c h inch of pressure drop c a n cost from $40,000 to $80,000, adds
PAY OFF IN REDUCED COST. Models correlate directly with full-scale units, give data on flues, blowers, a n d t h e like. Result is b e t t e r design and lower cost for a final precipitator like this one at a Standard Oil ( Calif. ) refinery
R-C. Their models, they claim, show it's possible to r e d u c e pressure loss b y V4 to one inch or m o r e . • No M o r e O v e r d e s i g n i n g . Smaller precipitators would m e a n lower construction cost. But manufacturers often build in a "safety factor" or extra capacity to account for uneven gas flow. Through models, R-C m a d e changes in flue designs (for example, eliminated sharp corners) w h i c h make it possible to bring t h e gas to the precipitator evenly distributed a n d without turbulence. W i t h gases arriving in such a state, smaller precipitators could b e m a d e and the "safety factor" forgotten. Also, larger units could handle still larger gas volumes. R-C's researchers, with their models, have found still more tricks to precipitator and auxiliary e q u i p m e n t design: • Drop-out h o p p e r s to trap dusts in flues are n o longer n e e d e d . T h e y increase turbulence a n d pressure drop.
• Baffles, flow splitters, and vanes have little or no effect on guiding gas flow. • Perforated plates used to distribute gases en route to the precipitator should not b e placed over hoppers. The gases will flow u n d e r the plates and sweep dust out of the hopper. Research-Cottrell has integrated model studies with its customer contracts. T h e company will build a model, study flue designs, and m a k e recommendations with or without a guarantee. Or, R-C will design, fabricate, and build t h e flues with a performance guarantee. T h e models can b e built in six t o eight weeks after prehminary drawings h a v e been made. Their cost will vary between 1 and 2% of t h e full scale precipitator. But this figure is small comp a r e d to the overall savings realized, explains R-C. m
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«3f J. BISHOP & CO. PLATINUM WORKS Malvern, MARCH
3,
Pennsylvania 1958
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