Generating Thermal Energy from the Sun

With the rising cost of electricity from fossil fuels, solar thermal energy (STE) currently leads the way as the most cost-effective solar technology. Major solar thermal power industry players are striving to make the economics of solar power a mainstream renewable energy source. While only 600 megawatts of solar thermal power was up and running worldwide in October 2009, another 400 megawatts is under construction and there are 14,000 megawatts of similar solar thermal projects being developed.

Solar thermal electric energy generation concentrates the light from the sun to create heat, and that heat is used to run a heat engine, which turns a generator to make electricity. Various methods exist to concentrate the solar radiation, including parabolic troughs, power towers with mirrors that track the sun, parabolic dishes, and Fresnel reflectors. A fluid (also called heat transfer fluid) like synthetic oil, molten salt and pressurized steam passes through the receiver and becomes very hot. The fluid containing the heat is transported to a boiler to produce steam which can then be used in the process or to generate electricity.

SIERRA'S SOLUTION

In California, a national brand of wheat snack chips is embracing solar thermal energy as an efficient and viable energy source for its factory. The installation of Sierra’s InnovaMass® 241 Multivariable Mass Vortex meters has greatly increased the efficiency of their thermal energy production, proving that investing in renewable energy directly impacts the bottom line.

The solar collector field at the chip manufacturing plant is comprised of a huge array of concave mirrors. These mirrors track the position of the sun throughout the day, focusing the sun’s energy on a black tube that runs along the focus of the array. This black tube is surrounded by a second glass tube vacuum chamber that protects it from the air, allowing it to absorb solar energy more effectively. As super-heated water passes through the black tube, the solar energy heats it up to 450°F. This is where Sierra’s 241 takes over to measure hot water, steam and condensate flow in the system. The water then runs through a boiler system that uses its heat to generate steam. The steam cooks the wheat and heats the cooking oil used in the manufacturing process. Cooled water flows back through the tube to the solar concentrator field to repeat the process.

InnovaMass® 241 vortex meters are optimized for high temperature and saturated steam applications up to 330,000 pounds/hour. The ability to sense all process conditions in a single installation location greatly improves measurement accuracy and eliminates the costly requirement for additional line penetrations associated with traditional mass flow measurement systems. With a +/- 1.5% accuracy for gases and a 30:1 turndown ratio, the InnovaMass® captures an industry edge for most steam generation and distribution applications.

Here’s what makes Sierra’s InnovaMass® 241 an ideal choice: » Measures mass flow directly with one meter to measure five process variables » Able to handle high temperatures and pressures whereas dP devices give erroneous readings in environments with varying pressure conditions » Onboard diagnostics and field configuration » Insertion design makes installation easy