Rapport (alle typer) - Danish Gas Technology Centre

DGC-report 18Among the possible required modifications are:Modification/change of control systemGas ramp for biogasModified gas ramp for natural gasNew or modified turbochargerCompressor for boosting the biogas pressureThe engine suppliers have assessed the necessary modifications and the relatedcost for different engine models. The costs related to conversion of theengines vary from around 300.000 DKK to 1.300.000 DKK depending onengine model, size and age. Possible costs for biogas boosters are not included.Furthermore, if the H 2 S content in the biogas is not sufficiently lowadditional service cost must be expected.7.1.2 Gas quality requirementsRolls Royce and GE Jenbacher have defined requirements regarding gasquality. Some of these are given in Table 4.Table 4Requirements to biogas quality given by engine manufacturesRolls-Royce GE JenbacherLowest heat value18 -[MJ/m 3 (n)]Gas temperature 20 - 40 °C 0 – 40 °CMoistureDew point: 5 °C @ 80 % relative4,3 barMax. particle size 5 µm 3 µmMax. sulphur 1520 mg/m 3 455 mg/m 3 1Max. ammonia 50 mg/m 3 32 mg/m 3Max. halogens 100 mg/m 3 65 mg/m 3 1(Cl + 2 x Fl)1 Valid for engines that are not equipped with catalysts.If the engines are equipped with CO or formaldehyde catalysts the concentrationof sulphur and halogens are lower than given in Table 4.The engine suppliers expect the electrical efficiency to decrease by around 1% point by conversion from natural gas to biogas operation. Depending onthe H 2 S concentration in the fuel it might be necessary to increase the fluegas temperature in order to avoid corrosion of heat exchangers. Jenbacherrecommends to increase the temperature after heat exchanger from around60 °C (which is normal for natural gas operation) to 180 °C if the H 2 S con-