Simone Colantoni

Rotary kiln slow pyrolysis for syngas and char production from biomass and waste -Part II Introducing product yields in the energy balance

A microscale electrically heated rotary kiln for slow pyrolysis of biomass and waste was designed and built at the University of Perugia. The reactor is connected to a wet scrubbing section, for tar removal, and to a monitored combustion chamber to evaluate the lower heating value of the syngas. The system allows the evaluation of gas, tar, and char yields for different pyrolysis temperature and residence time. The feeding screw conveyor and the kiln are rigidly connected; therefore a modification of the flow rate implies a modification of the inside solid motion and of residence time. Part I of the paper describes the theoretical and experimental evaluation of the working envelope of the reactor, that is, rotational speed as a function of feedstock density and humidity content, to obtain pyrolysis conditions inside the kiln. This paper describes the development and resolution of an energy balance of the reactor under pyrolysis conditions. Once the rotational speed n is fixed, the aim of the balance is to obtain the yield of wood biomass pyrolysis products such as syngas, tar, and char. Results can be used to choose the correct rotational speed of kiln and feeding screw before doing the real pyrolysis test.

Rotary Kiln Slow Pyrolysis for Syngas and Char Production From Biomass and Waste—Part I: Working Envelope of the Reactor

A microscale electrically heated rotary kiln for slow pyrolysis of biomass and waste was designed and built at the University of Perugia. The reactor is connected to a wet scrubbing section, for tar removal, and to a monitored combustion chamber to evaluate the lower heating value of the syngas. The system allows the evaluation of gas, tar, and char yields for different pyrolysis temperatures and residence times. The feeding screw conveyor and the kiln are rigidly connected; therefore, a modification of the flow rate implies a modification of the inside solid motion and of residence time. The paper provides the theoretical and experimental calculation of the relationships between residence time and flow rate used to determine the working envelope of the reactor as a function of the feedstock bulk density and moisture content, given the actual heat rate of the electric heaters. The methodology is extendable to any rotary kiln reactor with a rigidly connected feeding screw conveyor, given its geometric and energetic specifications. Part II of the paper will extend the energy balance, also introducing the yields of pyrolysis products.

Gas Turbines Fired With Biomass Pyrolysis Syngas: Analysis of the Overheating of Hot Gas Path Components

Alternative resources, such as biomass, and municipal and industrial waste are being considered as a source for the production of syngas to replace natural gas as a power turbine fuel. Pyrolysis of biomass produces a syngas composed primarily of CO, CO2, CH4, and H2 with a medium-low lower heating value that is strongly dependent on the process boundary conditions such as the pyrolysis temperature and product residence time in the reactor. The issues associated with conventional gas turbines also apply to syngas turbines with the added complexity of the fuel and impurities. At present, syngas turbines are operated at firing temperatures similar to those of turbines fired on natural gas by increasing the fuel mass flow through the turbine. While this produces a higher turbine power output, the heat transferred to the hot flow-path vanes and blades is also greater. The aim of this paper is to report on the use of numerical modeling to analyze the fundamental impact of firing gas turbines with biomass pyrolysis syngas. To complete the analysis, the results have been compared with data from the literature on gas turbines fired with coal gasification syngas. The test engine used to perform this analysis is a General Electric GE10-2 gas turbine. The performance, aerodynamics and secondary flows were computed using proprietary software, while a commercial finite element software was used to perform the thermal and local creep analyses.

Rotary Kiln Slow Pyrolysis for Syngas and Char Production From Biomass and Waste: Part 1 — Working Envelope of the Reactor

A micro scale electrically heated rotary kiln for slow pyrolysis of biomass and waste was designed and built at the University of Perugia. The reactor is connected to a scrubbing section, for tar removal, and to a monitored combustion chamber to evaluate the LHV of the syngas. The system allows the evaluation of gas, tar and char yields for different pyrolysis temperature and residence time. The feeding screw conveyor and the kiln are rigidly connected; therefore a modification of the flow rate implies a modification of the inside solid motion and of residence time. The paper provides the theoretical and experimental calculation of the relationships between Residence Time and Flow Rate used to determine the working envelope of the reactor as a function of the feedstock bulk density and moisture content, given the actual heat rate of the electric heaters. The methodology is extendable to any rotary kiln reactor with a rigidly connected feeding screw conveyor, given its geometric and energetic specifications. Part 2 of the paper will extend the energy balance introducing also the yields of pyrolysis products.Copyright

Thermodynamic Analysis and Possible Applications of the Integrated Pyrolysis Fuel Cell Plant (IPFCP)

Biomass and waste are generally considered as a very promising option for fossil fuel substitution and greenhouse effect reduction in a sustainable energy scenario. This paper examines the possible lay-out and performance of an innovative energy system based on the integration of a high temperature fuel cell with a pyrolysis reactor. The pyrolyzer converts biomass or solid waste into syngas, which is cleaned from impurities and feeds a Solid Oxide Fuel Cell (SOFC), operating at 1000°C. A combustor supplies the energy required for pyrolysis, burning the solid and liquid fraction of the pyrolysis yield, as well as the un-oxidized fuel leaving the cell anode. Literature data have been used for determining pyrolysis yield as a function of reactor temperature and evaluating its effect on the plant thermodynamic efficiency. The coupling of the system to a gas turbine using the fuel cell as its combustion chamber is also evaluated. Results show that very interesting efficiencies are obtainable in the 20%–30% range.© 2007 ASME

Rotary Kiln Slow Pyrolysis for Syngas and Char Production From Biomass and Waste: Part 2 — Introducing Product Yields in the Energy Balance

A micro scale electrically heated rotary kiln for slow pyrolysis of biomass and waste was designed and built at the University of Perugia. The reactor is connected to a scrubbing section, for tar removal, and to a monitored combustion chamber to evaluate the LHV of the syngas. The system allows the evaluation of gas, tar and char yields for different pyrolysis temperature and residence time. The feeding screw conveyor and the kiln are rigidly connected; therefore a modification of the flow rate implies a modification of the inside solid motion and of residence time. Part I of the paper describes the theoretical and experimental evaluation of the working envelope of the reactor, as a function of feedstock density and humidity content, to obtain pyrolysis conditions inside the kiln. This paper describes the development and resolution of an energy balance of the reactor under pyrolysis conditions. Once the rotational speed n is fixed, the aim of the balance is to obtain the composition of the yields of the pyrolysis of wood biomass, in terms of syngas, tar and char. Results can be used to choose the correct rotational speed before doing the real pyrolysis test.Copyright

Nozzle Guide Vane Assembly for Air-Cooled Retrofit Turbine Case Kit

Variable Guide Vanes are common to many of the Gas Turbines. Nozzle Guide Vane (NGV) is a variable nozzle present in the hot gas path of a twin-shaft gas turbine. In addition to guiding the hot gases onto the buckets, the NGV also controls the energy split between the high-pressure turbine and power turbine. The NGV is rotated to the desired position for different machine operability requirements through an actuation system. A twin shaft gas turbine equipped with NGV allows higher operational flexibility and higher efficiency at partial load/speed.MS3002F is a heavy duty gas turbine developed by GE in 1960’s with water cooling system for the turbine casing and the NGV. Over the period of time, technology has evolved and water cooling system in Gas Turbines has become obsolete, as it leads to uneven cooling of the casing and scaling that cause performance losses, unplanned outages and down-time. To cater the existing fleet with improved reliability and availability, a new product introduction program was launched to design air-cooled system to replace the water-cooled system, within the boundaries of retrofit ability. The air cooling is achieved by extracted secondary flow air; the reduction on performance due to this is compensated by increasing the firing temperature. Owing to the removal of water cooling and increased firing temperature, the turbine casing and hot gas path components including NGV have to be redesigned.The present paper discusses the redesign of the NGV assembly for new air-cooled configuration. This redesign includes geometry modification, assembly interface definition (contact geometry and coating), and material selection. The key challenge is to redesign the NGV with no cooling (neither water nor extracted secondary flow) while maintaining the steady state clearances of the NGV assembly as those of water-cooled kit. These redesigned components are validated for structural integrity under loads affecting fatigue, creep and oxidation. The verification of the functional integrity of NGV actuation system (that was originally designed for water-cooled system) for all operating conditions relevant to the new air-cooled turbine case kit is also discussed.Copyright