The coal, nuclear, natural gas, and oil industries are all familiar with the importance of water in production. From running complex systems of equipment, to cleansing their systems (and in the case of coal), to the product itself, water is an indispensable commodity.
A source of major concern since the mid-1900s, however, is the rate of consumption of water resources such applications require. Modern innovators have developed treatments and systems to address the ever growing industrial need for water without putting our planet's ecosystems at risk.
Industrial Application of Water
One of the greatest industrial applications of water is in thermoelectric power plants where, according to the USGS, "one of the main uses of water in the power industry is to cool the power-producing equipment.”
A report on industrial water usage by the Union of Concerned Scientists explains the process:
"Thermoelectric power plants boil water to create steam, which then spins turbines to generate electricity. The heat used to boil water can come from burning of a fuel, from nuclear reactions, or directly from the sun or geothermal heat sources underground.Once steam has passed through a turbine, it must be cooled back into water before it can be reused to produce more electricity. Colder water cools the steam more effectively and allows more efficient electricity generation”
The great paradox is that the cooling process heats the water in a basic exchange of thermal energy from solid to liquid. This heated water then becomes a threat to any natural ecosystem it may be dumped in, not only due to its heat but also because it may be contaminated during the flushing process.
Thus the treatment of cooling water has several goals. Of course, the water must be cooled to be effective in re-use, purged of contaminants for environmental safety and to prevent equipment damage, but most simply the modern goal for cooling water is the ability to reuse it.
The Advantages of Cooling Water Treatment
At Plymouth Technology, we know that when left uncontrolled, corrosion and deposition can lead to unscheduled maintenance, production down time and equipment failure. Moreover, businesses risk exposing their employees and community to serious health risks without effective treatment to control microbiological growth. However, as in the case of many serious risks, putting practical and preventative measures in place creates systems of control and greatly reduces risk.
1. Lowering water withdrawals
In an article appraising industrial and thermoelectric water systems, the Union of Concerned Scientists applauds wet-recirculating, or closed-loop, systems because they reuse cooling water and reduce the water withdrawals required to run the plant.
Closed loop systems, the UCS explains, "reuse cooling water in a second cycle rather than immediately discharging it back to the original water source. Most commonly, wet-recirculating systems use cooling towers to expose water to ambient air. Some of the water evaporates; the rest is then sent back to the condenser in the power plant.”
Significantly reducing the amount of new water required, the second cycle usage of cooling water as well as processes that merge treated water with fresh water are two techniques that have drastically reduced the water withdrawals of such plants.
2. Reducing wastewater amounts
Recently the National Energy Technology Laboratory (NETL), a branch of the U.S. Department of Energy (DOE), examined the produced water of recirculated cooling systems such as the one described above.
The NETL reports that "Oil and gas production generates wastewater: up to seven or eight barrels for every barrel of oil in the San Juan basin.”
Noting that "the need for further energy sources has caused oil and gas producers in the state to infill existing well fields and increase the pumping of water to enhance production,” the report focuses on a project in New Mexico to reduce the produced wastewater from plants by treating "the water for use as make-up water for re-circulating cooling systems in power generating stations.”
A recent blog post by the National Resources Defense Council states that the wastewater of oil and gas produced water threaten human drinking water as they "can contain benzene and other volatile organic compounds, heavy metals, radioactive materials, and more, and can be quite toxic.”
A major threat to environmental safety, it is essential to collect and treat the water from cooling systems.
3. Controlling biofouling and corrosion
If cooling water is treated, biofouling can be reduced or entirely prevented. A study on cooling water published by Hydrocarbon Engineering explains that it contains "the perfect ambience for all kinds of microorganisms, namely bacteria, algae and fungi, to thrive.” Because "cooling water typically has a moderate pH, mild temperatures,” it contains many of the "nutrients for microorganisms to survive and reproduce.
This microbiological growth easily becomes critical, especially with regards to hydrocarbon ingress, which increases the total organic carbon (TOC) and chemical oxygen demand (COD) of the water.” This combination of characteristics leads to biofouling, which can have costly effects on a business in the form of either maintenance and repair to expensive systems or in the halting or delay of production.
Another way in which cooling water treatment can increase efficiency and reduce the risk of revenue loss is in preventing corrosion. The increase of chemical oxygen demand, mentioned in the Hydrocarbon Engineering article, is hazardous to the metal of equipment and systems through which cooling water is flushed. High oxygen rates in water increase the risk of corrosion in the metal that in turn can cause cracks and ruptures in pipelines and parts.
A Quick Google image search on corrosion and biofouling produce enough chilling evidence to see the benefits of cooling water treatment, especially in the prevention of Microbiologically Influenced Corrosion (MIC). A recent study reveals that in the United States alone, corrosion damage is estimated to cost $276 billion/year, and the cost of corrosion in other countries generally accounts for 1-5% of the Gross National Product. MIC is estimated to cause 50% of the total cost of corrosion. http://cfm.mines.edu/research.html
4. Create clean energy options
Mexico is currently exploring how treating cooling water can create clean energy options and reduce greenhouse emissions. Among their areas of advancement, a Comtex article noted this spring, is an exploration of "combined heat and power” for industrial application.
Tecochill is a product line from the Mexican-based Tecogen company with "water-cooled engine-driven chillers, ranging from 150 to 400 tons of cooling capacity” in which "a natural gas engine drives a variable-speed single-screw rotary compressor, connected to a standard vapor compression refrigeration system utilizing environmentally-friendly HFC-134a refrigerant, delivering a highly-efficient cooling system, while capturing the waste heat for additional uses, such as hot water.”
A larger product line even uses "two engines for up to 400 tons of cooling capacity.” Tecogen is booming as these machines support the "effort to contain costs, lower emissions and hedge higher electricity rates” at industrial and thermoelectric sites
Such innovations are greatly increasing our ability to manage resource and energy consumption.
At Plymouth, we focus on controlling corrosion, scale, deposits, and microbiological fouling in closed, open evaporative, once through and closed loop cooling systems. By properly treating cooling water we see reduced corrosion rates, increased water conservation, prolonged equipment life, and reduced energy costs.