Solar collector field and thermal energy storage for auxiliary component in organic rankine cycle for bottoming unit to utilize exhaust steam from back pressure turbine of Ulumbu geothermal power plant

Abstract The intermittency of wind and solar energy can disrupt the dynamic balance utilities must maintain to meet fluctuating demand. This work examines the use of thermal energy storage (TES) to increase the operational flexibility of a baseload power plant and thus incentivize renewable energy and decarbonize the grid. A first and second law thermodynamic model of a nuclear power plant establishes the impacts of TES on the capacity factor and thermal efficiency of the plant. Four storage options, which are distinguished by the location within the cycle where steam is diverted for charging and whether discharge of the TES is via the primary or a secondary Rankine cycle, are considered. TES is compared to steam bypass, which is an alternative to provide baseload flexibility. TES is significantly better than steam bypass. The storage option with the greatest thermodynamic benefit is charged by diverting superheated steam at the outlet of the moisture separator/reheater (MSR) to the TES. The TES is discharged for peaking power through an optimized secondary cycle. TES increases the capacity factor as much as 15% compared to steam bypass at representative charging mass flowrates. The storage option that diverts steam from the steam generator to charge the TES and discharges the TES to the primary cycle extends the discharge power to a lower range and does not require a secondary cycle. In this case, the capacity factor and efficiency are as much as 8% greater than that of steam bypass.

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Addressing Industrial Waste Heat Supply Variability With Organic Rankine Cycle Systems Incorporating Thermal Energy Storage

10.21203/rs.3.rs-658624/v1 ◽

2021 ◽

Author(s):

Bipul Krishna Saha ◽

Basab Chakraborty ◽

Rohan Dutta

Keyword(s):

Power Generation ◽

Energy Storage ◽

Thermal Energy ◽

Thermal Energy Storage ◽

Power Plants ◽

Waste Heat ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Working Fluid ◽

Low Grade

Abstract Industrial low-grade waste heat is lost, wasted and deposited in the atmosphere and is not put to any practical use. Different technologies are available to enable waste heat recovery, which can enhance system energy efficiency and reduce total energy consumption. Power plants are energy-intensive plants with low-grade waste heat. In the case of such plants, recovery of low-grade waste heat is gaining considerable interest. However, in such plants, power generation often varies based on market demand. Such variations may adversely influence any recovery system's performance and the economy, including the Organic Rankine Cycle (ORC). ORC technologies coupled with Cryogenic Energy Storage (CES) may be used for power generation by utilizing the waste heat from such power plants. The heat of compression in a CES may be stored in thermal energy storage systems and utilized in ORC or Regenerative ORC (RORC) for power generation during the system's discharge cycle. This may compensate for the variation of the waste heat from the power plant, and thereby, the ORC system may always work under-designed capacity. This paper presents the thermo-economic analysis of such an ORC system. In the analysis, a steady-state simulation of the ORC system has been developed in a commercial process simulator after validating the results with experimental data for a typical coke-oven plant. Forty-nine different working fluids were evaluated for power generation parameters, first law efficiencies, purchase equipment cost, and fixed investment payback period to identify the best working fluid.

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