Pond, solar

Solar evaporation Solarization Solar panels Solar ponds Solar power systems Solar radiation Solar salt... 

At Great Salt Lake Minerals Corporation (Utah), solar-evaporated brines are winter-chilled to —3° C in solar ponds. At this low temperature, a relatively pure Glauber s salt precipitates. Ponds are drained and the salt is loaded into tmcks and hauled to a processing plant. At the plant, Glauber s salt is dissolved in hot water. The resulting Hquor is filtered to remove insolubles. The filtrate is then combined with soHd-phase sodium chloride, which precipitates anhydrous sodium sulfate of 99.5—99.7% purity. Great Salt Lake Minerals Corporation discontinued sodium sulfate production in 1993 when it transferred production and sales to North American Chemical Corporation (Trona, California). 

A third source of brine is found underground. Underground brines ate primarily the result of ancient terminal lakes that have dried up and left brine entrained in their salt beds. These deposits may be completely underground or start at the surface. Some of these beds ate hundreds of meters thick. The salt bed at the Salat de Atacama in Chile is over 300 m thick. Its bed is impregnated with brine that is being pumped to solar ponds and serves as feedstock to produce lithium chloride, potassium chloride, and magnesium chloride. Seades Lake in California is a similar ancient terminal lake. Brine from its deposit is processed to recover soda ash, borax, sodium sulfate, potassium chloride, and potassium sulfate. 

Solar Evaporation. Recovery of salts by solar evaporation (1 3) is favored in hot dry climates. Solar evaporation is also used in temperate 2ones where evaporation exceeds rainfall and in areas where seasons of hot and dry weather occur. Other factors (4,5) affecting solar pond selection are wind, humidity, cloud cover, and land terrain. 

Solar ponds are typically 15—50 cm deep. They are usually built over flat areas, where silts and clays have settled to make a tight soil base to prevent leakage through the bottom of the pond. In areas where soils are not tight, artificial liners of mbber or poly(vinyl chloride) (PVC) are used. 

Until the 1970s, solar ponds were constmcted and operated as more of an art than a science. Since then, rising land value, environmental conscientiousness, limited space, and rising costs have forced a scientific approach to solar pond optimization, design, and operation to make ponds more productive. 

Where possible, solar salt is replacing vacuum salt because of rising energy costs. For example, in July the 81 x 10 (20,000 acres) of solar ponds... 

In 1981, seven faciUties extracted minerals from Great Salt Lake brine, but flooding in 1983 and 1984 reduced the number to five. By 1992, four companies were operating. AH Great Salt Lake mineral extracting faciUties have solar ponds as the first stage in processing minerals from brine. 

Recovery Process. Lithium is extracted from brine at Silver Peak Marsh, Nevada, and at the Salar de Atacama, Chile. Both processes were developed by Foote Mineral Corp. The process at Silver Peak consists of pumping shallow underground wells to solar ponds where brines are concentrated to over 5000 ppm. Lithium ion is then removed by precipitation with soda ash to form a high purity lithium carbonate [554-13-2]. At the Atacama, virgin brine with nearly 3000 ppm lithium is concentrated to near saturation in lithium chloride [7447-41 -8]. This brine is then shipped to Antofagasta, Chile where it is combined with soda ash to form lithium carbonate. 

Recovery Process. The Texas Gulf, Cane Creek potash operation (60) of Moab, Utah produces KCl by solution mining (61—64). Brine is pumped from underground to 1.6 x 10 (400 acres) of solar ponds where a mixture of KCl and NaCl is crystallized in a salt mass called sylvinite. 

Production of KCl at the Wendover, Utah operation employs a large 7000 acre complex of solar ponds. Both shallow brine wells and deeper wells are used to pump brine into the pond complex. In the preconcentration ponds water is evaporated and sodium chloride is crystallized. Later the brine is transferred to production ponds where sylvinite is deposited. Brine is then transferred to other ponds where camaUite is crystallized. Sylvinite is removed from drained ponds with self-loading scrapers and taken to the plant were KCl is separated by flotation with an amine oil collector. The camaUite,... 

Great Salt Lake Minerals Corp. near Ogden, Utah, produces potassium sulfate and several other products from Great Salt Lake brines. Presently 81 X 10 (20,000 acres) is divided into 80 solar ponds with 81 million m of expansion scheduled in 1992. Two years are requked to process brine... 

Recovery Process. Figure 5 shows a typical scheme for processing sodium chlodde. There are two main processes. One is to flood solar ponds with brine and evaporate the water leaving sodium chlodde crystallized on the pond floor. The other is to artificially evaporate the brine in evaporative crystallizers. Industrial salt is made from solar ponds, whereas food-grade salt, prepared for human consumption, is mosdy produced in the crystallizers. 

A solar pond does not concentrate solar radiation, hut collects solar energy in the pond s water by absorbing both the direct and diffuse components of sunlight. Solar ponds contain salt in high concentrations near the bottom, with decreasing concentrations closer to the surface. This variation in concentration, known as a salt-density gradient, suppresses the natural tendency of hot water to rise, thus... 

BASE AND METHODOLOGY FOR THE ESTIMATION OF WORKER INJURY RATES. THERMAL ENERGY STORAGE SYSTEMS. ROUTINE FAILURE HAZARDS. OFF-NORMAL EVENTS. SOLAR PONDS. (1979) (Spon-... 

Build a small-scale model of a solar pond and test how it traps and stores solar energy. 

Construct a small-scale solar pond using simple materials. 

Collect temperature data as the solar pond model heats and cools. 

Water is transparent to visible light but opaque to infrared radiation. How do you think these properties will affect your solar pond model ... 

If you used only tap water in your model, convection currents would bring warmer, less dense water from the bottom to the surface. Do you think this will happen with your solar pond model Explain your answer. 

The next day, prepare the solar pond model. Place the black plastic dish on the lab bench where you want to run the experiment. Use a small piece of waterproof tape to attach one of the temperature probes to the bottom of the black plastic dish. Plug this probe into Channel 1 of the CBL System. Slowly pour the 100 mL of saturated salt solution into the dish. 

Position the 150-watt lightbulb about 15 to 20 cm over the top of the solar pond model. Turn on the light. Press ENTER on the calculator to begin collecting data. After about 6 to 8 minutes, turn off the lightbulb and move it away from the solar pond model. Do not disturb the experiment until the calculator is finished with its 30-minute run. 

Comparing and Contrasting Which layer of your solar pond model did the best job of trapping and storing heat ... 

The El Paso Solar Pond was the first in the world to successfully use solar pond technology to store and supply heat for industrial processes. It was built with three main layers a top layer that contains little salt, a middle layer with a salt content that increases with depth, and a very salty bottom layer that stores the heat. Which layer has the greatest density The least density Why doesn t the storage layer in the El Paso Solar Pond cool by convection ... 

Finkelstein, E. J. Heat Recovery Syst. 3 (1983) 431-437. On solar ponds critique, physical fundamentals and engineering aspects. 

Much of this chapter has been concerned with various modifications to the simple Rankine cycle at high temperature. In the following five sections, the Rankine cycle that makes possible use of energy sources at low temperature, such as solar, geothermal, ocean thermal, solar pond, and waste heat, will be discussed. Because of the small temperature range available, only a simple Rankine cycle can be used and the cycle efficiency will be low. This is not critical economically, because the fuel is free. 

A solar pond heat engine is a small-scale, inverse OTEC system. In this system, a shallow (l-2m deep) pond saturated with a salt is used as the primary solar collector. As the surface waters of the pond are heated by the solar radiation, the solubility of this warm water increases and the... 

A proposal is made to use a solar pond supply of bottom pond hot water at 100 kPa and 80° C to operate a steam turbine. The 100 kPa-pressure bottom pond water is throttled into a flash evaporator chamber, which forms liquid and vapor at a lower pressure of 20kPa. The liquid is discarded while the saturated vapor feeds the turbine and exits at lOkPa. Cooling water is available at 15°C. Find the turbine power per unit geothermal hot-water mass flow rate. The turbine efficiency is 80%. Find the power produced by the solar pond power plant. 

Review Problems 2.11 Solar Pond Heat Engines... 

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