Biomass Conversion and Biorefinery

, Volume 4, Issue 1, pp 1–14

Biomass heat pipe reformer—design and performance of an indirectly heated steam gasifier

Original Article

DOI: 10.1007/s13399-013-0102-6

Cite this article as:
Karl, J. Biomass Conv. Bioref. (2014) 4: 1. doi:10.1007/s13399-013-0102-6

Abstract

Indirectly heated dual fluidized bed (DFB) gasifiers are a promising option for the production of syngas, in particular in the small- and medium-scale range. The application of so-called heat pipes solves the key challenge of indirectly heated gasifiers—the heat transfer into the gasifier's reformer part. Performance, technical challenges, and solutions for the so-called biomass heat pipe reformer are discussed, and the development of the last 10 years is summarized. An equation for the heat pipe reformer's cold gas efficiency is presented. The equation applies for any dual fluidized bed gasifier and indicates that the efficiency of the combustion process dominates the cold gas efficiency of any directly or indirectly heated allothermal steam gasification system.

Keywords

BiomassAllothermal gasificationHeat pipes

Nomenclature

a, amin

(Stoichiometric) air demand (kilogramsair/kilogramfuel)

b

Fuel-to-bed material ratio (kilogramsbed material/kilogramfuel)

cp

Specific heat (kilojoules per kilogram per Kelvin)

Hl

Lower heating value (kilojoules per kilogram)

Hi

Molar enthalpy (kilojoules per kilomole)

ΔHr

Heat of reaction (kilojoules per kilomole)

ΔHv

Heat of evaporation (kilojoules per kilomole)

\( \overset{\cdot }{m} \)

Mass flow (kilograms per second)

\( \overset{\cdot }{n} \)

Molar flow (kilomoles per second)

\( {\tilde{M}}_{{}_i} \)

Molar mass (kilograms per kilomole)

m, n

Molar fraction of hydrogen and oxygen in the fuel (–)

\( \overset{\cdot }{Q} \)

Energy flow, heat demand, heat flux (kilowatts)

\( \overset{\cdot }{q} \)

Specific heat demand (–)

\( \varDelta {\overset{\cdot }{Q}}_{\varDelta \mathrm{h},\mathrm{r}} \)

Heat of reaction for the endothermal gasification reactions (kilowatts)

\( \varDelta {\overset{\cdot }{Q}}_{\varDelta \mathrm{h},\mathrm{v}} \)

Heat of evaporation for the evaporation of the fuel's moisture (kilowatts)

\( \varDelta {\overset{\cdot }{q}}_{\varDelta \mathrm{h},\mathrm{r}} \)

Specific heat of reaction for the endothermal gasification reactions (–)

\( \varDelta {\overset{\cdot }{q}}_{\varDelta \mathrm{h},\mathrm{v}} \)

Specific heat of evaporation for the evaporation of the fuel's moisture (–)

s, smin

(Stoichiometric) steam demand (kilogramssteam/kilogramfuel)

t

Temperature (Kelvin)

w

Moisture content of fuel (kilogramswater/kilogramfuel)

xchar

Char content (kilogramschar/kilogramfuel)

Greek letter

ηcg

Cold gas efficiency (–)

ηcomb

Combustor efficiency (–)

λ

Excess air ratio (–)

σ

Excess steam ratio (–)

νI

Stoichiometric coefficient (–)

φchar

Char conversion rate (–)

Subscripts

a

Air

bm

Bed material

char

Char

comb

Combustion chamber

f

Fuel

fg

Flue gas

HP

Heat pipe

In

Input

s

Steam

sens

Sensible heat

sg

Syngas

Abbreviations

DFB

Dual fluidized bed

CHP

Combined heat and power

AER

Absorption enhanced reforming

HPR

Heat pipe reformer

BioHPR

Biomass heat pipe reformer

MBG

Moving bed gasification

SNG

Substitute natural gas

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  1. 1.Lehrstuhl für EnergieverfahrenstechnikFriedrich-Alexander-Universität Erlangen-NürnbergNurembergGermany