Influence from fuel type on the performance of an air-blown cyclone gasifier

Abstract

h i g h l i g h t sPerformance of an air-blown cyclone gasifier have been investigated for different fuels. Cleaning system performance have been investigated with SMPS. Carbon conversion varied between 70% and 95% for the different fuels. Entrained flow gasification of biomass using the cyclone principle has been proposed in combination with a gas engine as a method for combined heat and power production in small to medium scale (<20 MW). This type of gasifier also has the potential to operate using ash rich fuels since the reactor temperature is lower than the ash melting temperature and the ash can be separated after being collected at the bottom of the cyclone. The purpose of this work was to assess the fuel flexibility of cyclone gasification by performing tests with five different types of fuels; torrefied spruce, peat, rice husk, bark and wood. All of the fuels were dried to below 15% moisture content and milled to a powder with a maximum particle size of around 1 mm. The experiments were carried out in a 500 kW th pilot gasifier with a 3-step gas cleaning process consisting of a multi-cyclone for removal of coarse particles, a bio-scrubber for tar removal and a wet electrostatic precipitator for removal of fine particles and droplets from the oil scrubber (aerosols). The lower heating value (LHV) of the clean producer gas was 4.09, 4.54, 4.84 and 4.57 MJ/Nm 3 for peat, rice husk, bark and wood, respectively, at a fuel load of 400 kW and an equivalence ratio of 0.27. Torrefied fuel was gasified at an equivalence ratio of 0.2 which resulted in a LHV of 5.75 MJ/Nm 3 which can be compared to 5.50 MJ/Nm 3 for wood powder that was gasified at the same equivalence ratio. A particle sampling system was designed in order to collect ultrafine particles upstream and downstream the gasifier cleaning device. The results revealed that the gas cleaning successfully removed >99.9% of the particulate matter smaller than 1 lm. a r t i c l e i n f o

Online Characterization of Syngas Particulates Using Aerosol Mass Spectrometry in Entrained-Flow Biomass Gasification

“…The use of the second dilution setup made sure that a sufficient total dilution ratio could be achieved at all time and to lower the particle concentration to a level suitable for the particle analysis instruments. This dilution system is described in detail elsewhere (Nilsson et al 2011(Nilsson et al , 2013Risberg et al 2014). The dilution probe was 300 mm in length and consisted of an outer tube (i. d. 12 mm) surrounding an inner tube (i.d.…”

Numerical modeling of a 500 kW air-blown cyclone gasifier

“…The gas can either be fed to a gas engine (12) to produce electricity or it can be flared (13). The char and ash that was collected in the char bin (5) was quenched with nitrogen and the amount was measured by weighing after the experiment was completed. The product gas composition was analyzed, using a micro-gas chromatograph (Varian 490-GC) with two thermal conductivity detectors (TCD), with respect to CO, H 2 , CO 2 , N 2 , O 2 , CH 4 , C 2 H 4 and C 2 H 2 .…”

“…One possible technology that has the potential to overcome these problems is cyclone gasification in combination with a gas engine that drives a generator, followed by heat recovery from the engine exhaust gases. The cyclone configuration has been shown to work well with a variety of fuels and with ash contents up to 20% [5]. In this scenario, it will be very important to optimize plants of different scales so that the efficiency is maximized with the constraint that the plant size should be as small as possible to keep investment costs down.…”

“…Ideally, this should be done with a suitable computer model since it would be too costly to do the optimization experimentally. However, although several experimental studies have been carried out on cyclone gasification for example by Risberg et al [5] and Zhao et al [6], only a few numerical simulations have been published. One example is the work by Gao et al [7] who simulated a 100 kW cyclone gasifier, using the commercial CFD code Fluent and implementing models of biomass pyrolysis, oxidation and reduction.…”

Turbulence Modelling of a Single-Phase Flow Cyclone Gasifier

“…In a cyclone gasifier, pulverized biomass fuel is fed together with air tangentially Engineering along the inside surface of a cyclone geometry [1] [2] [3]. Partial combustion inside the cyclone gasifier generates a high temperature that results in conversion of the powder to a medium heating value gas and possibly also a small char residue.…”