PRODUCTION Waste Brines Go Underground Du Pont's a diponitrile plant sends 100 g a l . per min. of waste products to subsurface disposal units GALVESTON, TEX.—During two and a half years, 100 million gallons of waste concentrated sodium chloride brine have b e e n returned underground in D u Pont's subsurface disposal system. Waste brine from adiponitrile ( a nylon intermediate) production also contains dissolved metallic: salts and organic compounds ira small amounts. Using techniques similar t o oil well salt water injection, this brine is disposed of in a way which doe?s not pollute other underground w a t e r s . H. O. Henkel of D u P o n t ' s Victoria, Tex., plant disclosed t h e development of its brine disposal --wells at the A I C h E South Texas Section annual technical meeting. Henkel points to economic considerations ^which rule out piping or barging t h e brixie o u t into the Gulf of Mexico. High salt content also rules out solar evaporation and submerged combustion. D u Pont initially ixnnounded its waste brine in diked ba.sins when t h e Victoria plant opened i n 1951. But growing quantities of birine forced t h e company t o drill its first well two years later. As time went o n , pressure required to inject the waste brine underground rose to about 120 p.s.i.g. for 100 gallons per minute of brine. A second well was drilled in 1954 to ensure adequate well infection capacity for outages a n d increased brine rates. Chemical changes i n brine composition and alternating well usage caused well head pressure to drop—fears lessened that No. 1 well woxild ÏDe permanently plugged. • Cost Experiences. Henkel says disposal wells are expensive, particularly if the brine is more corrosive than natural brine. T h e total cost of D u Pont's first well w a s i n t h e neighborhood of $250,000, but the second well cost much less. T h e second well's lower cost is attributed to applying experiences w i t h the first well. In the second well, sand formations were already known, s o less coring and exploratory work n e e d e d t o b e done. Less expensive p i p i n g with a baked phenolic resin lining was substituted for aluminum-broxize piping for t h e "well string. Then, a casing oil seal was used for the NO. 2 well, eliminating 4854
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need for a packer and casing pressurizing equipment. Both wells were drilled over 4500 feet deep. To reduce t h e possibility of contaminating usable fresh water, No. 1 well is equipped with a cemented steel surface casing extending 2500 feet down from the surface, and No. 2 well liras a similar casing 2000 feet down. These casings meet state law requirements. Both wells also have 7-inch o.d. steel inner casings extending their total depth. These casings are cemented in and are lined with a phenolic resin for protection against corrosion. No. 1 well has the annulus between the string a n d casing filled with inhibited fresh water under automatically controlled pressure. Experiences with this well showed that No. 2 well could use oil for the filler between string and casing. Diesel oil w a s used proving simpler and more versatile t h a n a packer seal. And Diesel oil eliminated the need for a corrosion inhibitor which was necessary with water. • Preiniection T r e a t m e n t . Before waste brine can b e injected underground, it must be m a d e free from suspended solids, stable, and unreactive with the natural brine and underground sand in t h e well. Otherwise, precipitates would plug well sands prematurely, indicates Henkel.
Du Pont scientists established t w o criteria for evaluating untreated brine quality for underground injection. First, no precipitate should form while the brine stands eight hours at 60° C , the approximate temperature a t 4000 to 5000 feet below the surface. Second, the brine w h e n passing through well sand cores, should not decrease sand permeability. Stability t o precipitate formation is a criterion for treated and natural brines from the well also. Precipitate usually has been caused by metal precipitation or organic materials degradation, or both. Most precipitates are removed in a baffled settling basin providing about 16 hours holdup. Remaining solids are removed in a pressure filter packed with graded anthracite coal. Then a final polishing filtration using precoated, porous carbon tube filters takes out small particles. These tubes will hold a n y solid particles larger than 15 microns. Both filters have back washing facilities. Well sands require very stable brine, free of suspended solids. Screen analysis of a typical sand sample showed nearly 100% passing through 100-mesh and 20% through 200-mesh. Perforation of the sands is necessary, initially, and after well head pressures become relatively high. The brine as it comes from the manufacturing process is cooled and neutralized with caustic solution. After settling a n d filtration, the brine is pumped t o the wells at 7.5 t o 8.0 pH and 30° t o 40° C . Well pumps are capable of delivering 250 gallons per minute at about 1O00 feet head. • Well Performance Calculations. Because o f the time required to drill a well, knowledge of existing well capacity is important. Henkel explains how Du Pont engineers measure well performance—they developed an index expressed b y dividing flow to a well by
DuPont's P r e i n j e c t i o n Brine T r e a t m e n t
HOT W A S T E B R I N E
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BAFFLES
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POROCARBON FILTERS (Four)
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•^37.5-8-0 pH PUMPS
TO No· 2
"S>
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THEBIGSHIPMENT THAT DIDN'T PAY OFF!
It was the vital first order o f a n all-important new account. But the shipment was returned with a terse "merchandise spoiled due to seepage." This can't happen with products properly c a p p e d with the new Polyseal C l o s u r e d The Polyseal Closure prevents leaking, evaporation, contamination, binding or back-off of the cap. Your shipment arrives a t its destination exactly as it was first bottled protected from chemical o r compositional balance change· The users of Polyseal h a v e found that capping their products with the new Polyseal Closure is less expensive to their firm in the long run. A t the 25th Exposition of the Chemical Industry, Philadelphia, Dec. 5 to 9 Booth 528, see how the Polyseal Closure \ prevents spoilage.
ITS
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Closure in o p e n position.
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The P o l y - s e a l d o s u r ilways in the .right .position over 'the open finish o f the container.
Closure in fully seated position. (Tension is locked in the structure of the cone.) Note the complete conforming action of the liner to the vertical and horizontal areas of the finish. Surface irregulari ties are minimized.
The polyethylene liner is secured permanently
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'become dislodged or fall out.
THE POLYSEAL CORPORATION Chrysler Building 405 Lexington Avenue, New York 17, Ν. Υ. Telephone MUrray Hill 5-4172 t U . S. Patent Pending
©1955
protruding
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Eastman
triethyl phosphate may be the answer to your search far: α n o n - c o r r o s i v e solvent w i t h l o w t o x i c i t y α fine lubricant additive a m i l d e t h y l a t i n g agent
CHARACTERISTICS Color, Α Ρ Η Λ
10 max.
Specific Gravity, 20°/2O°C Acidity, as H3PO4
Î .067-1.072 0 . 0 3 % max.
Boiling R a n g e . . 9 7 % between 2 0 9 ^ 2 1 8 ° C Flesh Point. Weight Per Gallon, 2 0 ° C .
240°F . . 8 . 9 0 lbs
a starting m a t e r i a l for insecticide m a n u f a c t u r e a useful catalyst f o r : the dehydration of g l y c o l s the synthesis oF esters the polymerization o f certain m o n o m e r s
Eastman triethyl phosphate is soluble in w a t e r and most organic solvents. It is very resistant to hydrolysis a t ordinary temperatures. !t is quite useful as an ethylating agent, for all three of its ethyl groups are available.
Eastman CHEMICAL PRODUCTS, INC. KINGSP0RT, TENNESSEE A subsidiary of EASTMAN KODAK COMPANY
Triethyl phosphate reacts with phosphorus pentoxide or o x y trichloride to yield poly esters which have unusual properties a s insecticides. These complex esters also show some promise as rodenticides. W e ' l l b e g l a d to send you detailed information and sample quantities of Eastman triethyl phosphate for your evaluation. Write to Eastman Chemical Products, Inc., Chemicals Division, Kingsport, Tennessee.
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7,
1955
PRODUCTÎON
Outstanding Ο pportuni
ty
FOR YOUNG SCIENTISTS •
Chemical Engineers
•
Organic Chemists
•
Physical Chemists
9 mechanical Engineers
D u Pont's N o . 1 b r i n e disposal we!ï nt Vîotorî.a. Tex, net pressure forcing brine into the well. Net pressure equals the sum of pressures forcing brine into the sand (well head pressure and brine column p r e s s u r e ) , less bottom hole pressure. Bottom hole pressure changes very little. Effectively, then, the index measures the sand formation's brine receiving ability—roughly comparable to s a n d permeability. Daily evaluation of well performance by the index found it to b e reasonably reliable regardless of flow rate fluctuations. Performance index for No. 1 w e l l was very high initially. For the first two months of operation, t h e fluid level in the well string was below t h e point where pressure was measured; essentially a vacuum existed. T h e n the well index dropped. Henkel believes the drop c a m e from plugging of both casing perforations and possibly adjacent sand. Efforts to open t h e well h a d temporary success. In 1954 plant process changes w e r e made, altering the brine chemical composition. Then apparently the plugging began to dissolve a n d the index for No. 1 well climbed. When N o . 2 well was drilled and received most of the brine, the index continued t o climb, indicating more plug dissolution wliile standing unused. N o w with both wells operating alternately, and with n e w brine composition, t h e indexes h a v e been steady or just slightly d r o p p i n g . • Disposal System O p e r a t i o n . Poor injected brine stability causes well plugging. Therefore, Du Pont tries to keep t h e brine producing manufacturing step under control. I t shoots for a minimum variation in brine composi-
tion and minimum concentration of precipitate-forming substances. S u s p e n d e d solids in the brine cause well plugging. A constant check is made b y D u Pont on the polishing filters to b e sure that no suspended solids leak through. Air en trainmen t in the injected brine causes temporary well capacity loss. Air decreases brine specific gravity a n d hence decreases well string static pressure. Air also restricts brine flow through well sands giving the effect of well plugging. Further, Henkel points out that air will oxidize ferrous iron in natural brines to precipitating ferric iron. T o minimize air entrainment possibilities, wells are usually operated with flows high enough to give pressures at t h e well h e a d s rather than low flow with a vacuum at the well head. Henkel concludes that Du Pont's first venture in subsurface waste disposal has b e e n successful. "And t h e r e is every indication that w e can continue successfully this method of disposal, " h e said.
ί Beck m α η I n s t r u m e n t s has cut break age costs in shipping its scientific in struments to just about an absolute minimum. Solution to w h a t was a per plexing problem is b y the use of "bis cuits" m a d e of compressed sugar cane. The biscuits are scooped out so that the two opposing sides of the instru ment can b e securely cradled in t h e m . The instrument is t h e n slipped into a paper carton box, a small accessory box placed b e t w e e n t h e biscuits, and car ton is r e a d y for shipment.
One of the world's largest manufac turers of man-made fibers has an op portunity for young scientists. Its principal production is ccllulosic fibers, but its extensive research facilities con stantly explore the entire field of manmade fibers. Courtaulds ^Alabama) i n c > has a new production plant and research facilities in Mobile, Alabama. It is anxious to obtain several young men w h o have not placed a ceiling on their professional attainment. The Company wants young men of proven scholarship and unlimited ability t o grow. The oppor tunity for advancement is great because the Mobile operation is young and the staff is still quite small. Courtaulds needs four CHEMICAL ENGINEERS whose interests arc in rhe direction of plant technical prob lems or research. These men should be recent honor graduates, with a desire ro further their professional growth in a substantial company which is sym pathetic to academic and professional attainment. An opportunity can be provided for such young scientists to associate with some of the outstanding people in the man-made fiber field. Courtaulds needs the same type of scientists in ORGANIC CHEMISTRY and PHYSICAL CHEMISTRY, and can provide the same opportunities as noted above. MECHANICAL ENGINEERS arc needed in the Engineering Department for design work on new plant and modifications calling for a great deal of automation. Qualification standards for all appoint ments are extremely rigid, because the opportunity for growth is great and the remuneration is comparable.
Send full particulars
to:
Director of Industrial Relations Courtaulds (Alabama) Inc. P. O . Box 1076 Mobile, Alabama
NOV.
7,
1955
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