Prereforming features

Prereforming is used for low-temperature steam reforming of hydrocarbon feedstocks ranging from natural gas to heavy naphtha. 

Converting higher hydrocarbons in the prereformer results in stable and mild operating conditions for a downstream tubular reformer and thus ensures reliable operation of the tubular reformer.

Prereforming allows operation at low steam to carbon ratio and thereby reduces the overall energy consumption. The prereformer also increases the lifetime of the tubular reformer and the shift catalysts, as the sulphur present in the hydrocarbon feed and process steam is absorbed by the prereforming catalyst.

Prereforming process layout

The prereformer is placed upstream of the tubular reforming unit. In order to obtain the required steam to carbon ratio, feedstock is mixed with process steam before entering the prereformer. In the prereformer, all higher hydrocarbons are converted into a mixture of carbon oxides, hydrogen and methane at equilibrium based on the methanation and water gas shift reactions.

Focal points

Prereforming may be used in the debottlenecking of existing plants, and the majority of new Topsoe licensed plant designs include a prereforming step.

Topsoe offers prereforming catalysts which cover the entire range of feedstocks from natural gas to heavy naphtha.