Development and Testing of a 10 MWe Supercritical CO2 Turbine in a 1 MWe Flow Loop

Abstract

sCO2 power cycles offer improved cycle efficiencies compared with traditional steam Rankine cycles. However, the turbomachinery required to support such a cycle does not exist at a commercial scale and requires development. This paper describes a new 10 MWe scale sCO2 turbine was developed and demonstrated in an sCO2 closed-loop recompression Brayton cycle. Since this turbine was developed for Concentrating Solar Power (CSP) applications, a target inlet temperature of over 700°C was chosen using funding from the US DOE SunShot initiative and industry partners. However, it can be applied to traditional heat sources such as natural gas, coal, and nuclear power. Traditional Rankine steam cycle thermal efficiencies are typically in the 35–40% range, but can be as high as 45% for advanced ultra-supercritical steam cycles. The sCO2 cycle can approach 50% thermal efficiency using externally fired heat sources. Furthermore, this cycle is also well suited for bottoming cycle waste heat recovery applications, which typically operate at lower temperatures. The high-power density and lower thermal mass of the sCO2 cycle results in compact, high-efficiency power blocks that can respond quickly to transient environmental changes and transient operation, a particular advantage for solar, waste heat, and ship-board applications. The power density of the turbine is significantly greater than traditional steam turbines and is comparable to liquid rocket engine turbo pumps. This paper describes the design and construction of the turbine and provides additional testing of the 10 MWe turbine in a 1 MWe test facility including a description of rotordynamics, thermal management, rotor aero and mechanical design, shaft-end and casing seals, bearings, and couplings. Test data for the turbine is included, as it achieves its operational goal of 715°C, 250 bara, and 27,000 rpm.

Supercritical CO2 Power Technology: Strengths but Challenges

“…After three decades during which these pioneering works were neglected [10], a series of development programs began mainly in the USA, Japan and Korea, using test rigs of a few dozen kWe [11][12][13][14][15][16][17][18]. However, these tests revealed a series of unexpected and arduous issues, including disturbing CO 2 leaks that proved difficult to control; operation instabilities with difficulties reaching stationary loads and thermal stresses experienced by turbine materials at temperatures above 500 • C. Therefore, although significant progress has been made in understanding the general requirements of this technology in terms of hardware, systems and controls, these programs have not to date resulted in a generic prototype designs suitable for large power blocks.…”

Review of Carnot Battery Technology Commercial Development

“…No other working fluid is considered in these directly heated systems. The reason, except for being the industrial standard, can be found in its higher efficiency compared to ORC systems and the fact that CO 2 cycles at high temperatures have seen only very few demonstrators built so far (e.g., CSP application [57] or Allam cycle for gas combustion [58]). Technically, the direct heating with steam cycle can be considered as the simplest technology.…”

Demonstration of a small‐scale power generator using supercritical CO2

“…Many research institutions have achieved significant progress in experimental investigations of turbomachinery, which are summarized in Table 1. In addition, other US organizations designed and conducted experimental tests of sCO 2 power cycles from the MW‐scale to 10 MW‐scale in areas of waste heat recovery and concentrated solar power, including the Echogen 53,54 and Southwest Research Institute (in collaboration with GE Global Research) 55–57 . Universities in Europe, such as Brunel University and the University of Duisburg‐Essen, also designed and constructed sCO 2 power cycle test loops 58,59 …”

“…In addition, other US organizations designed and conducted experimental tests of sCO 2 power cycles from the MW-scale to 10 MWscale in areas of waste heat recovery and concentrated solar power, including the Echogen 53,54 and Southwest Research Institute (in collaboration with GE Global Research). [55][56][57] Universities in Europe, such as Brunel University and the University of Duisburg-Essen, also designed and constructed sCO 2 power cycle test loops. 58,59 The abovementioned research primarily focused on the power generation system from the 100 kW to MW scales.…”