Adding gas from biomass to the gas grid - SGC

In all countries gas in a distribution grid (low-pressure grid) has to be odorised. With someexceptions, the gas in a transport grid (high pressure) is not odorised.The addition of propane and odorant are simple low cost process steps. The propane additionrequires a feed back control loop to maintain the Wobbe number within the local contractual limits.The measurement equipment in this control system can also provide data on the delivered calorificvalue of the gas. § 4.4 describes the addition of propane.The addition of the odorant requires a flow proportional dosing system. Even simple odorisationequipment performs quite well. § 4.6 describes the addition of the odorant.5.4 PROCESS INTEGRATIONThe production of pipeline quality gas from syngas only needs proven technology in astraightforward process using basic process equipment at moderate pressure and temperatureconditions. The combination of gasification of biomass and the production of pipeline quality gas isnew and requires an integral concept. This concept may use:• gasification of biomass with water as main reagent• oxygen (not air) as additional reagent• recovery in the balance of plant of the heat evolved in the gasification step in the methanation.All the pyrolysis processes (appendix 2: Batelle/Ferco, Brightstar, EVN, Gibros, Noell, Thermoselectand Thermogenics) meet these requirements fairly well. Table 22 gives a survey of the impact of theconversion and upgrading steps.WaterCleanSyngasConversionConverted syngasRemovalcarbon dioxidepipelinequalitygascarbon dioxideFigure 11: Schematic process flow diagram for the production of pipeline quality gas from cleansyngas originating from pyrolysis based processespage: 54