By a News Reporter-Staff News Editor at Drug Week — A patent application by the inventors VANDENDOREN, Alain (Brussels, BE); MOTE, Jessica A. (Kaycee, WY), filed on December 18, 2013, was made available online on July 3, 2014, according to news reporting originating from Washington, D.C., by NewsRx correspondents (see also Solvay Sa).
This patent application is assigned to Solvay Sa.
The following quote was obtained by the news editors from the background information supplied by the inventors: “Evaporative ponds dimensioning relies mainly among parameters to local water precipitations from rain, ambient air temperature during the year, and the wind velocity conditions forcing heat convection.
“One way to accelerate the evaporation is to increase the temperature of the liquor relatively to the ambient air temperature and its associated dew point. Another way to accelerate the evaporation is to increase the contact surface between air and the liquor comprising water to be partially evaporated. Among those ways, spraying systems enable to divide a liquor into droplets having more evaporation specific surface area than the more or less flat surface of the corresponding liquor stored in a pond. Though operating spraying devices with aqueous solutions comprising water and sodium carbonate and optionally other soluble salts such as sodium bicarbonate, sodium chloride, or sodium sulfate leads to fast scaling and clogging of those spraying devices at the outlet of the spraying devices when water is evaporated.
“Among the industries using evaporative ponds, soda ash production from natural ores or from alkaline lakes is one of them. The main natural ores comprising sodium carbonate are: trona, nahcolite or wegscheiderite ores. Those natural ores can be found in different geographical areas such as Brazil, China, Kazakhstan, Mexico, Turkey, USA (Wyoming, Colorado, California). Alkaline lakes are found mainly in Africa. Those natural ores can be mechanically mined, for instance using longwall equipments, or be mined by solution mining with water.
“The production of soda ash and its derivatives from natural ore or from alkaline lakes, results in the production of purge streams containing sodium carbonate. Indeed most of the natural deposits contain impurities such as insoluble particles (sand, clay, calcium carbonate, feldspar, . . . ) and soluble salts mainly evaporite salts (sodium chloride, sodium sulfate, . . . ).
“The impurities must be removed from the process lines to guarantee a final product quality required for main uses of soda ash: such as glass production, or food and pharmaceutical production of refined sodium bicarbonate. Most of the soluble impurities such as soluble salts or less soluble compounds are removed from the production process as aqueous solutions or aqueous suspension comprising aqueous solution in different purge streams containing sodium carbonate.
“Generally the soluble impurities are removed by a purge control during the crystallization steps in order to guarantee the final soda ash or soda ash derivative quality.
“Moreover when using a solution mining an higher amount of water is used per ton of soda ash or soda ash derivatives compared to a conventional dry mining operation, increasing therefore the needs to control the water balance and the evaporation energy optimization when combining evaporative ponds and industrial evaporators fed with steam from a steam generator.
“U.S. Pat. No. 1,859,275 (1932) discloses a manufacturing process of sodium carbonate from salt residues of alkaline waters in Owens Lake (California). The document teaches to avoid the building and operating of evaporation ponds to store summer brine of the lake. It teaches to use steam to melt crystals of sodium carbonate decahydrate and sodium chloride in a sodium sulfate rich brine and reach the three solid phases sodium carbonate monohydrate, Na.sub.2CO.sub.3.2Na.sub.2SO.sub.4 double salt, and sodium chloride to precipitate double salt to decrease sodium sulfate concentration of the brine. The double salt is removed from the resulting brine and purified sodium carbonate decahydrate is then crystallized. The document is silent on the use of indirect heating by using a heat exchanger to enhance the evaporation of the evaporation pond, silent on the use of spraying device and on spraying conditions.
“US2003/0143149 discloses a process for recovering the sodium carbonate from evaporative pond water using heat to heat a sodium carbonate recovery stream before introducing it to an evaporation pond (20). The pond liquor is heated at 120-140.degree. F. (49-60.degree. C.) before being causticized with caustic or quicklime. The described process is silent on the use of spraying device and spraying conditions. It is also silent on multi-ponds operation.
“The present invention aims to propose an improved method for increasing the evaporation rate of an evaporative pond containing a sodium carbonate solution using spraying device and low temperature heat or waste heat, in particular from a steam generator or from a soda ash plant.”
In addition to the background information obtained for this patent application, NewsRx journalists also obtained the inventors’ summary information for this patent application: “The invention relates to a method for increasing the evaporation rate of an evaporative pond containing pond liquor comprising water and at least 1\% by weight of sodium carbonate, said evaporative pond being in contact with an ambient air at an ambient air temperature of more than 0.degree. C., the method comprising the following steps: feeding part of the pond liquor to a heat exchanger, heating the pond liquor in the heat exchanger with heat and producing a heated pond liquor, feeding the heated pond liquor into a spraying device at a temperature called hereafter ‘operating temperature’ of at least 10.degree. C., preferably at least 15.degree. C., more preferably at least 20.degree. C. above the ambient air temperature, spraying the heated pond liquor into an open area of the evaporative pond with the spraying device, so as to evaporate at least part of the water of the pond liquor when sprayed.
“A first advantage of the present invention is to improve the operation conditions of enhance evaporation devices using spraying systems for pond liquors containing sodium carbonate.
“A second advantage of the present invention is the increased evaporation rate of an evaporative pond containing a sodium carbonate pond liquor increasing the annual evaporation rate per surface unit of pond.
“A third advantage of the present invention is the increased period of time during the year during which evaporation takes place, in particular in the off-season for instance in northern hemisphere (in southern hemisphere seasons should be inversed): early spring (March-April) and late fall (October-November). This almost double the time period of efficient evaporation compared to the main evaporation period (May to September in northern hemisphere, November to March in southern hemisphere) when only natural evaporation is used without using enhanced evaporation systems and heat.
“A fourth advantage of the present invention is to increase the convection locally in the evaporative pond areas where the pond liquor is removed to be fed into the spraying device and where the pond liquor is sprayed back; this generates a more uniform concentrations of the pond liquor in the evaporative pond and this improves also the convection and evaporation at the ambient air/pond liquor interfaces, in particular during off-season where sodium decahydrate crystals are generated on surface of the ponds during colder nights or days.
“A fifth advantage of the present invention is the possibility of combined synergy between evaporative ponds of liquors containing sodium carbonate and low temperature heat or waste heat from a steam generator and in particular from a soda ash plant using a steam generator, decreasing therefore the carbon foot print of such processes.
“A sixth advantage of the present invention is the possibility of combined synergy between such enhanced evaporation devices with increased concentration of sodium chloride or sodium sulfate in the generated sodium carbonate liquor in the evaporative pond, that enables to reduce the clogging speed of enhanced evaporative devices. This is also particularly advantageous when enhanced evaporation devices are combined with multi-ponds management techniques such as techniques using at least one decahydrate sodium carbonate crystallizing pond associated with an evaporative pond and/or an evaporative-double salt crystallizing pond.
BRIEF DESCRIPTION OF THE DRAWINGS
“FIG. 1 is a schematic illustration of an embodiment of the method in accordance with the principles of the present invention.
“FIG. 2 is a schematic illustration of an embodiment of the method in accordance with the principles of the present invention.”
URL and more information on this patent application, see: VANDENDOREN, Alain; MOTE, Jessica A. Method for Increasing Evaporation Rate of an Evaporative Pond. Filed December 18, 2013 and posted July 3, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=\%2Fnetahtml\%2FPTO\%2Fsearch-adv.html&r=7364&p=148&f=G&l=50&d=PG01&S1=20140626.PD.&OS=PD/20140626&RS=PD/20140626
Keywords for this news article include: Anions, Alkalies, Chemicals, Chemistry, Solvay Sa, Carbonic Acid, Sodium Sulfate, Sodium Chloride, Sodium Carbonate, Sodium Compounds, Hydrochloric Acid.
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