Cellulose slow pyrolysis products in a pressurized steam flow reactor

A key strategy to achieve an acceptable degree of matter and energy recovery from vegetal waste disposal is the use of a steam-assisted pyrolysis process that operates at low heating rates and elevated pressure. This procedure, which is different from incineration and fast pyrolysis processes, is expected to reduce the production of secondary hazardous products and produce a residual char with chemical–physical properties comparable to those typical of activated carbon. However, gaseous and condensable products of the process must be demonstrated to allow for a recovery of energy to an extent that can make the process self-sustainable. To clarify these aspects and define the optimal operating conditions of the process, a multi-plate laboratory reactor was designed and constructed. This paper provides a description of the primary design criteria and operating conditions for a steam pyrolysis process. In addition, the effects of process temperature and pressure on products yields and gas and char characteristics are presented indicating the suitability of the process. In the temperature range examined, steam affects positively char and gas properties. On the other hand, pressure affects, mainly, gas yield and determines only minimal changes in char characteristics.