Operational Experience of a Centrifugal Particle Receiver Prototype

The centrifugal particle receiver “CentRec” is a solar tower receiver development by DLR based on a direct absorption receiver concept especially suitable for high temperature process heat and electricity generation applications. Ceramic particles are used as heat transfer and storage medium for temperatures up to 1000°C. A centrifugal particle receiver system including a CentRec receiver prototype has been tested up to 965°C average receiver outlet temperature in the research platform of DLR’s test facility Juelich Solar Tower, Germany. This paper describes the first test results with a focus on first operational experiences

Oxidationskinetik innovativer Kohlenstoffmaterialien hinsichtlich schwerer Lufteinbruchstörfälle in HTR's und Graphitentsorgung oder Aufarbeitung

Currently future nuclear reactor concepts of the Fourth Generation (Gen IV) are underdevelopment. To some extend they apply with new, innovative materials developed just for thispurpose.This thesis work aims at a concept of Generation IV Very High Temperature Reactors (VHTR) inthe framework of the European project RAPHAEL (ReActor for Process heat, Hydrogen AndELectricity generation). The concept named ANTARES (AREVA New Technology based onadvanced gas-cooled Reactors for Energy Supply) was developed by AREVA NP. It is a heliumcooled, graphite moderated modular reactor for electricity and hydrogen production, by providingthe necessary process heat due to its high working temperature.Particular attention is given here to oxidation kinetics of newly developed carbon materials (NBG-17) with still unknown but needed information in context of severe air ingress accident in VHTR’s.Special interest is paid to the Boudouard reaction, the oxidation of carbon by CO2. In case of anair ingress accident, carbon dioxide is produced in the primary reaction of atmospheric oxygenwith reflector graphite. From there CO2 could flow into the reactor core causing further damage byconversion into CO. The purpose of this thesis is to ascertain if and to what degree this couldhappen.First of all oxidation kinetic data of the Boudouard reaction with NBG-17 is determined byexperiments in a thermo gravimetric facility. The measurements are evaluated and converted intoa common formula and a Langmuir-Hinshelwood similar oxidation kinetic equation, as input forthe computer code REACT/THERMIX. This code is then applied to analyse severe air ingressaccidents for several air flow rates. The results are discussed for two accident situations, in whicha certain graphite burn off is achieved. All cases show much more damage to the graphite bottomreflector than to the reactor core. Thus the bottom reflector will lose its structural integrity muchearlier than the core itself will be damaged by oxidation

Oxidationskinetik innovativer Kohlenstoffmaterialienhinsichtlich schwerer Lufteinbruchstörfälle inHTR’s und Graphitentsorgung oder Aufarbeitung

Currently future nuclear reactor concepts of the Fourth Generation (Gen IV) are underdevelopment. To some extend they apply with new, innovative materials developed just for thispurpose.This thesis work aims at a concept of Generation IV Very High Temperature Reactors (VHTR) inthe framework of the European project RAPHAEL (ReActor for Process heat, Hydrogen AndELectricity generation). The concept named ANTARES (AREVA New Technology based onadvanced gas-cooled Reactors for Energy Supply) was developed by AREVA NP. It is a heliumcooled, graphite moderated modular reactor for electricity and hydrogen production, by providingthe necessary process heat due to its high working temperature.Particular attention is given here to oxidation kinetics of newly developed carbon materials (NBG-17) with still unknown but needed information in context of severe air ingress accident in VHTR’s.Special interest is paid to the Boudouard reaction, the oxidation of carbon by CO2. In case of anair ingress accident, carbon dioxide is produced in the primary reaction of atmospheric oxygenwith reflector graphite. From there CO2 could flow into the reactor core causing further damage byconversion into CO. The purpose of this thesis is to ascertain if and to what degree this couldhappen.First of all oxidation kinetic data of the Boudouard reaction with NBG-17 is determined byexperiments in a thermo gravimetric facility. The measurements are evaluated and converted intoa common formula and a Langmuir-Hinshelwood similar oxidation kinetic equation, as input forthe computer code REACT/THERMIX. This code is then applied to analyse severe air ingressaccidents for several air flow rates. The results are discussed for two accident situations, in whicha certain graphite burn off is achieved. All cases show much more damage to the graphite bottomreflector than to the reactor core. Thus the bottom reflector will lose its structural integrity muchearlier than the core itself will be damaged by oxidation

Abteilung für Großanlagen und Solare Materialforschung�

Vorstellung des Instituts für Solarforschung und er Abteilung Großanlagen und Solare Materialforschun

First On-Sun Tests of a Centrifugal Particle Receiver System

One direct absorption receiver concept currently investigated at the DLR is the Centrifugal Particle Receiver (CentRec®). Successful tests and promising results of this receiver design have been achieved in a Proof-of-Concept scale with 7.5 kW thermal power and 900°C particle temperature in 2014. Based on these results the prototype has been scaled up to 2.5 MW thermal power for a future pilot plant. Lab tests have been carried out with infrared heaters. In a next step the prototype has been prepared to be tested on-sun in a test setup in the Juelich Solar Tower, Germany. The tests aim to demonstrate high temperature operation and to evaluate the performance of the system. The test setup consists of a centrifugal receiver integrated into the tower and a closed loop particle transport system. The transport system includes an air cooling system to cool down the particles at the receiver outlet, cold particle storage, belt bucket elevator, hopper and particle metering system. While the 2.5 MWth receiver prototype has been developed in a former project, the further infrastructure for the on-sun tests needed to be designed, manufactured and installed. The system is equipped with measurement instrumentation, data acquisition system and control software. Manufacturing of all main components has been completed. Installation of the test setup started in November 2016 and finished in June 2017. Cold and hot commissioning have been carried out from July 2017 until September 2017. On-sun tests started in September 2017. Receiver tests up to 775°C/1,430°F receiver outlet temperature and more than 900°C/1,650°F particle temperature in the receiver have already been achieved. Tests up to 900°C particle outlet temperature are planned at different load levels and will be conducted until summer 2018. This paper describes the test setup for a centrifugal particle receiver system, presenting design, installation and commissioning of the system. It presents test results of first onsun tests and gives an outlook on further steps regarding solar tests planned for 2018

Experimental evaluation of a pilot-scale thermochemical storage System for a concentrated solar power plant

A first of its kind pilot-scale redox-based thermochemical storage system has been set up and operated under near-realistic conditions inside a solar power tower plant. The storage unit is made of inert honeycomb supports (cordierite) coated with 88 kg of redox active material (cobalt oxide). An experimental campaign has been carried out consisting of 22 thermochemical charge-discharge cycles. The heat absorbed or released by the chemical reaction became clearly evident through the temperature Evolution inside the reactive material. It allows to store or release energy at constant temperature when crossing respectively the reduction/oxidation temperature of the Co3O4/CoO pair. A storage performance factor (PF) was defined to evaluate how each experiment approaches the ideal behavior. During the complete campaign no measurable cycle-to-cycle degradation was observed and the system average capacity was very close to the ideal case of PF = 0.84. The advantage of thermochemical storage could be quantified by comparing the storage capacity, to that of a sensible-only storage unit made of uncoated cordierite honeycombs. The thermochemical system offered almost double storage capacity (47.0 kW h) cf. the same volume of the sensible-only case (25.3 kW h)