Maarky Thermal Systems designs quality-engineered heat transfer equipment that enables power plants to function optimally. The full range of Maarky Thermal Systems offerings includes feedwater heaters and exchangers, as well as steam surface condensers. The latter systems are critical in maximizing plant output through decreasing back-pressure.
For combined-cycle power plants, one focus is on ensuring that turbine bypass operations are seamless and allow consistent performance. With steam turbine out of service, high temperature and pressure steam from the heat recovery steam generator is directed into a pressure reducing desuperheating (PRD) valve that reduces pressure and temperature of the bypass steam to a desired value. The bypass steam at relatively low pressure and temperature is discharged into the condenser.
Optimally-engineered steam surface condenser systems offer reliable performance during normal and bypass operation. The bypass steam inlet arrangement is carefully designed so as to alleviate damage to tubes from steam impingement. The bypass steam flow patterns are carefully deciphered using the state of the art Computational Flow Dynamics (CFD) programs.
Offering leading edge heat-transfer equipment, Maarky Thermal Systems meets the needs of a global client base of power producers. In June 2016 Maarky Thermal Systems president Dr. Ranga Nadig presented at the ASME Power and Energy Conference in Charlotte, North Carolina, on the topic “Evacuation Systems for Steam Surface Condensers: Vacuum Pumps or Steam Jet Air Ejectors?”
In steam power plants, steam released from the turbine undergoes condensation within a vacuum environment that is cooled by either air or water. One common problem involves air leaking into the condenser through faulty seals, valves, and flanged connections. As this has a negative impact on condensing functions, non-condensable air that becomes trapped in the system must be continuously evacuated.
A key question plants face is whether to use motor-driven vacuum pumps or steam-driven jet air ejectors. This decision involves weighing factors such as costs, motive steam availability, and end user preferences. Some plants bridge these differences through multi-stage hybrid systems that are effective in operations requiring low suction pressure.
At an international industry conference in December 2015, Maarky Thermal Systems president Dr. Ranga Nadig delivered his paper entitled “Nitrogen Based Thermal Storage Medium for Concentrated Solar Power Plants”. The said paper is a patent pending concept of Maarky Thermal Systems.
The paper notes that in a Concentrated Solar Power Plant, thermal storage is used to negate the loss of electrical power generation at night. At daytime the thermal storage material is heated to higher temperatures and then stored in huge containers. In the evening, high pressure steam is generated using the energy from the heated material. This high pressure steam powers a turbine generator which produces electricity.
The preferred thermal storage material is molten salt. Using molten salt poses a number of difficulties. This includes having to obtain it in large amounts and transporting it to the solar plant which may be in a remote location. Inconsistencies in the salt composition can cause changes in thermal properties and melting temperature. The freezing point of molten salt is also at 550ºF needing expensive additives to lower the freezing point.
Using nitrogen has a number of advantages over molten salt. It can be simply be extracted from the air at the plant site and with 80 percent of the atmosphere composed of nitrogen the supply is abundant and free. It can be stored in huge containers and has stable thermodynamic properties. The freezing problem no longer exists as nitrogen stays in gaseous state over a wide temperature range.
Ranga Nadig is president of Maarky Thermal Systems, which is based in New Jersey. The company provides steam surface condensers, feedwater heaters, and heat exchangers – as well as consulting services to power plants worldwide. Maarky Thermal Systems is recognized worldwide for its innovative and reliable equipment designs. The company was recently invited to join the condenser section of the Heat Exchange Institute, one of the frontrunners in developing industry standards.
Since 1933, the Heat Exchange Institute has been helping to organize and represent North American manufacturers who own manufacturing facilities or are responsible for the manufacturing of products that meet the organization’s requirements. As the Institute grew, it created a set of standards to guide manufacturers.
One of these standards applies to steam surface condensers. The performance of power plants employing wet cooling is strongly dependent on the performance of the steam surface condenser. HEI standards for steam surface condensers include guielines for thermal and mechanical design that ensures structural integrity and reliable performance.