A Pb/Zn Based Chemical Looping System for Hydrogen and Power Production With Carbon Capture

2011 ◽  
Author(s):  
Niall R. McGlashan ◽  
Peter R. N. Childs ◽  
Andrew L. Heyes
Keyword(s):  
Power System ◽  
Flue Gas ◽  
Power Output ◽  
Carbon Capture ◽  
Oxygen Carrier ◽  
Fluid Phase ◽  
Chemical Looping Combustion ◽  
Inlet Temperature ◽  
Chemical Looping ◽  
Lower Efficiency

This paper describes an extension of a novel, carbon-burning, fluid phase chemical looping combustion system proposed previously. The system generates both power and H2 with ‘inherent’ carbon capture using chemical looping combustion (CLC) to perform the main energy release from the fuel. A mixed Pb and Zn based oxygen carrier is used, and due to the thermodynamics of the carbothermic reduction of PbO and ZnO respectively, the system generates a flue gas which consists of a mixture of CO2 and CO. By product H2 is generated from this flue gas using the water-gas shift reaction (WGSR). By varying the proportion of Pb to Zn circulating in the chemical loop, the ratio of CO2 to CO can be controlled, which in turn enables the ratio between the amount of H2 produced to the amount of power generated to be adjusted. By this means, the power output from the system can be ‘turned down’ in periods of low electricity demand without requiring plant shutdown. To facilitate the adjustment of the Pb/Zn ratio, use is made of the two metal’s mutual insolubility, as this means they form in to two liquid layers at the base of the reduction reactor. The amount of Pb and Zn rich liquid drawn from the two layers and subsequently circulated around the system is controlled thereby varying the Pb/Zn ratio. To drive the endothermic reduction of ZnO formed in the oxidiser, hot Zn vapour is ‘blown’ into the reducer where it condenses, releasing latent heat. The Zn vapour to produce this ‘blast’ of hot gas is generated in a flash vessel fed with hot liquid metal extracted from the oxidiser. A mass and energy balance has been conducted for a power system, operating on the Pb/Zn cycle. In the analysis, reactions are assumed to reach equilibrium and losses associated with turbomachinery are considered; however, pressure losses in equipment and pipework are assumed to be negligible. The analysis reveals that a power system with a second law efficiency of between 62% and 68% can be constructed with a peak turbine inlet temperature of only ca. 1850 K. The efficiency varies as the ratio between power and H2 production varies, with the lower efficiency occurring at the maximum power output condition.

scholarly journals Efficient Production of Clean Power and Hydrogen Through Synergistic Integration of Chemical Looping Combustion and Reforming

Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3443
Author(s):  
Mohammed N. Khan ◽  
Schalk Cloete ◽  
Shahriar Amini
Keyword(s):  
Oxygen Carrier ◽  
Combined Cycle ◽  
Chemical Looping Combustion ◽  
Inlet Temperature ◽  
Efficient Production ◽  
Chemical Looping ◽  
Reactor Outlet ◽  
Point Energy ◽  
Highly Efficient ◽  
Energy Penalty

Chemical looping combustion (CLC) technology generates power while capturing CO2 inherently with no direct energy penalty. However, previous studies have shown significant energy penalties due to low turbine inlet temperature (TIT) relative to a standard natural gas combined cycle plant. The low TIT is limited by the oxygen carrier material used in the CLC process. Therefore, in the current study, an additional combustor is included downstream of the CLC air reactor to raise the TIT. The efficient production of clean hydrogen for firing the added combustor is key to the success of this strategy. Therefore, the highly efficient membrane-assisted chemical looping reforming (MA-CLR) technology was selected. Five different integrations between CLC and MA-CLR were investigated, capitalizing on the steam in the CLC fuel reactor outlet stream to achieve highly efficient reforming in MA-CLR. This integration reduced the energy penalty as low as 3.6%-points for power production only (case 2) and 1.9%-points for power and hydrogen co-production (case 4)—a large improvement over the 8%-point energy penalty typically imposed by post-combustion CO2 capture or CLC without added firing.

scholarly journals Transient Cold Flow Simulation of Fast-Fluidized Bed Air Reactor with Hematite as an Oxygen Carrier for Chemical Looping Combustion

2021 ◽  
Vol 11 (5) ◽  
pp. 2288
Author(s):  
Pulkit Kumar ◽  
Ajit K. Parwani ◽  
Dileep Kumar Gupta ◽  
Vivek Vitankar
Keyword(s):  
Fluidized Bed ◽  
Carbon Capture ◽  
Oxygen Carrier ◽  
Stable Solution ◽  
Flow Simulation ◽  
Chemical Looping Combustion ◽  
Chemical Looping ◽  
Discrete Phase Model ◽  
Particle Injection ◽  
Cold Flow

Chemical looping combustion (CLC) is the most reliable carbon capture technology for curtailing CO2 insertion into the atmosphere. This paper presents the cold flow simulation results necessary to understand the hydrodynamic viability of the fast-fluidized bed air reactor. Hematite is selected as an oxygen carrier due to its easy availability and active nature during the reactions. The dense discrete phase model (DDPM) approach using the commercial software Ansys Fluent is applied in the simulation. An accurate and stable solution is achieved using the second-order upwind numerical scheme. A pressure difference of 150 kPa is obtained between the outlet and inlet of the selected air reactor, which is necessary for the movement of the particle. The stable circulating rate of hematite is achieved after 28 s of particle injection inside the air reactor. The results have been validated from the experimental results taken from the literature.

An Innovative Gas Turbine Cycle With Methanol-Fueled Chemical-Looping Combustion

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Hongguang Jin ◽  
Xiaosong Zhang ◽  
Hui Hong ◽  
Wei Han
Keyword(s):  
Low Temperature ◽  
Gas Turbine ◽  
Carbon Capture ◽  
Power Plants ◽  
Waste Heat ◽  
Carbon Capture And Storage ◽  
Chemical Looping Combustion ◽  
Inlet Temperature ◽  
Chemical Looping ◽  
Gas Turbine Cycle

In this paper, a novel gas turbine cycle integrating methanol decomposition and the chemical-looping combustion (CLC) is proposed. Two types of methanol-fueled power plants, including the new gas turbine cycle with CLC combustion and a chemically intercooled gas turbine cycle, have been investigated with the aid of the T-Q diagram. In the proposed system, methanol fuel is decomposed into syngas mainly containing H2 and CO by recovering low-temperature thermal energy from an intercooler of the air compressor. After the decomposition of methanol, the resulting product of syngas is divided into two parts: the part reacting with Fe2O3 is sent into the CLC subsystem, and the other part is introduced into a supplement combustor to enhance the inlet temperatures of the gas turbine to 1100–1500°C. As a result, the new methanol-fueled gas turbine cycle with CLC had a breakthrough in thermodynamic and environmental performance. The thermal efficiency of the new system can achieve 60.6% with 70% of CO2 recovery at a gas turbine inlet temperature of 1300°C. It would be expected to be at least about 10.7 percentage points higher than that of the chemically intercooled gas turbine cycle with the same recovery of CO2 and is environmentally superior due to the recovery of CO2. The promising results obtained here indicated that this novel gas turbine cycle with methanol-fueled chemical-looping combustion could provide a promising approach of both effective use of alternative fuel and recovering low-temperature waste heat and offer a technical probability of blending a combination of the chemical-looping combustion and the advanced gas turbine for carbon capture and storage.

Multicycle Study on Chemical Looping Combustion with a CaSO4-CaO Mixed Oxygen Carrier

2019 ◽  
Vol 17 (10) ◽  
Author(s):  
Pu Sixu ◽  
Zheng Min ◽  
Liu Yulou ◽  
Zhao Zhitong ◽  
Sarma Pisupati
Keyword(s):  
Environmental Factor ◽  
Carbon Capture ◽  
Oxygen Carrier ◽  
Total Carbon ◽  
Molar Ratio ◽  
Chemical Looping Combustion ◽  
Chemical Looping ◽  
Molar Ratios ◽  
Fuel Reactor ◽  
High Concentrations

Abstract Chemical looping combustion (CLC) is a carbon capture technology which enables CO2 capture with low net efficiency penalty. Calcium sulfate (CaSO4) is an optional oxygen carrier for commercial use, but its usage is limited due to sulfur dioxide (SO2) emission. This study approaches this issue by adding CaO species into the CaSO4 oxygen carrier to inhibit the release of SO2 from CaSO4 oxygen carrier. In this study, the cyclical tests of a CaSO4-based oxygen carrier under alternating reducing and oxidizing conditions were performed at 900 °C and 800 °C respectively in a tubular furnace reactor at atmospheric pressure. The effects of reducing gas concentration and molar ratio of CaO/CaSO4 on the performance of CaSO4-CaO oxygen carrier were studied in terms of CO2 yields, Environmental factors of SO2 and COS, molar ratios of gas sulfides to CO2 generated in fuel reactor, and molar ratios of SO2 and COS to total carbon inlet. The use of CaO additive increased the yields of CO2 obviously. The release of COS in the fuel reactor and SO2 in the air reactor decreased, but while the overall release of SO2 in the fuel reactor increased. However, for per mole CO2 generation, less gas sulfides released from the fuel reactor. High concentrations of CO were beneficial for CO2 production and a low SO2 environmental factor, and meanwhile, the molar ratios of SO2 released to inlet CO {{\text{n}}_{{\text{S}}{{\text{O}}_2}}}/{{\text{n}}_{{\text{CO}}}} decreased. However, it led to a drop in CO2 yield and an increase in COS environmental factor. As a whole, the use of CaO additive and higher CO concentration both accelerated the parallel CaSO4 reductions in fuel reactor, especially the selectivity of CaSO4 reduction to CaS.

Simulation of Chemical Looping Hydrogen Production Using Solid Fuel

2013 ◽  
Vol 724-725 ◽  
pp. 1254-1257 ◽  
Author(s):  
Long Fei Wang ◽  
Shu Zhong Wang ◽  
Ming Luo
Keyword(s):  
Hydrogen Production ◽  
Solid Fuel ◽  
Flue Gas ◽  
Carbon Capture ◽  
Oxygen Carrier ◽  
Chemical Looping ◽  
Gas Composition ◽  
Reactor Performance ◽  
Simulation Results ◽  
Effects Of Temperature

Chemical looping hydrogen production (CLH) has become a promising technology for hydrogen production with inherent separation of carbon dioxide. This paper simulated the three reactors of CLH process of coal as solid fuel using Aspen Plus. The effects of temperature, oxygen carrier/coal ratio, steam/coal ratio, and the air/coal ratio on the gas composition in specific reactor were discussed. Simulation results showed that the temperature had a great effect on the reactor performance. The optimized OC/coal ratio in the OC/coal ratio in this paper was 19.1. The CO2 fraction in the flue gas of FR reached 87.5% when the vapor was condensed at the temperature of 950 °C. The fraction of dry-based H2 in the SR was almost 100% when the SR temperature was 815 °C and the steam/coal ratio was 18.8. The simulation confirmed that the CLH process showed high potential in hydrogen production and the carbon capture.

A Thermodynamic Analysis of Chemical Looping Combustion

2011 ◽  
Author(s):  
Andrew L. Heyes ◽  
Loukas Botsis ◽  
Niall R. McGlashan ◽  
Peter R. N. Childs
Keyword(s):  
Carbon Dioxide ◽  
Thermodynamic Analysis ◽  
Gas Turbines ◽  
Carbon Capture ◽  
Oxygen Carrier ◽  
Inert Gases ◽  
Chemical Looping Combustion ◽  
Chemical Looping ◽  
Oxygen Carriers ◽  
And Storage

Recently, interest has grown in chemical looping combustion (CLC) because it is seen as a technique that may allow cost-effective carbon capture and storage (CCS). In CLC the overall reaction by which chemical energy is released is between a hydrocarbon and air as in conventional combustors. However, the reaction is completed in two separate oxidation and reduction steps occurring in different reaction vessels. In the oxidizer (or air reactor) an oxygen carrier, usually a metal, is exothermically oxidized in air resulting in an oxide and a hot air stream (oxygen depleted). The exhaust gasses may be expanded through a turbine to produce work, while the oxide passes to the reduction vessel (or fuel reactor). Here, it reacts with the fuel, is reduced and the metal regenerated. The metal then returns to the oxidizer to complete the loop. The exhaust gasses from the reducer contain only carbon dioxide and water so that, after expansion and work extraction, the water may be condensed leaving a stream of pure CO2 ready for storage. Hydrocarbon fuels will continue to be used for decades, so, in the face of ambitious emission reduction targets, CCS is an important technology and methods, such as CLC, that offer automatic CO2 separation (so-called inherent carbon capture) are particularly attractive. Despite this obvious advantage CLC was not originally conceived for the purposes of CCS, but rather as a means to produce pure carbon dioxide free from contamination by inert gases such as nitrogen. In the context of power generation it was then proposed as a means to improve the exergetic efficiency of energy conversion processes using hydrocarbons. Combustion is usually a highly irreversible process and necessitates the rejection of large quantities of heat from power cycles leading to the low thermal efficiency of gas turbines and the like. The two-stage reaction approach of CLC can reduce the irreversibility and the extent of heat rejection and hence provide improved cycle efficiency. Ideally, both goals would be simultaneously achieved thereby offsetting both the cost of carbon capture and of compression, transportation and storage. In the paper we present a thermodynamic analysis of CLC to illustrate its potential for improving efficiency. We will then develop a methodology for selecting oxygen carriers based on their thermodynamic properties and review several candidate materials. In particular, we will compare, from a thermodynamic perspective, solid phase oxygen carriers as used in fluidised bed based reaction systems and the liquid/vapour phase carriers previously suggested by the authors. Finally, comments on practical implementations of CLC in power plant will be presented.

Reactivity of a NiO/Al2O3 oxygen carrier prepared by impregnation for chemical-looping combustion

Fuel ◽  
2010 ◽  
Vol 89 (11) ◽  
pp. 3399-3409 ◽  
Author(s):  
Cristina Dueso ◽  
Alberto Abad ◽  
Francisco García-Labiano ◽  
Luis F. de Diego ◽  
Pilar Gayán ◽  
...  
Keyword(s):  
Oxygen Carrier ◽  
Chemical Looping Combustion ◽  
Chemical Looping
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