Injection of additive into a unit for synthesising hydrocarbons starting from synthesis gas enabling a homogenous concentration of catalyst to be controlled and maintained

摘要

The invention relates to a process for synthesising hydrocarbons starting from a feedstock containing synthesis gas. In the process a solid Fischer-Tropsch catalyst is employed in a three-phase reaction section operated so that the catalyst is maintained in suspension in a liquid phase by the circulation of a gaseous phase from the bottom to the top of the reaction section. The process utilizes conditions to control and maintain the homogeneity of the concentration of catalyst particles in the reaction section.

主权项

1. A process for synthesizing hydrocarbons starting from a feedstock containing synthesis gas, comprising:
reacting said feedstock in a three-phase reaction section in which solid Fischer-Tropsch catalyst particles are maintained in suspension in a liquid phase by circulation of a gaseous phase from the bottom to the top of said reaction section, the catalyst suspension in the liquid phase forming a slurry, wherein the following stages are carried to control and maintain homogeneity of the concentration of said solid Fischer-Tropsch catalyst particles in said reaction section: (a) measuring the differential pressures ΔPi between two consecutive pressure measuring points spaced apart by Δhi and calculating the pressure drops per meter ΔGi=ΔPi/Δhi for all i between 1 and n-1, wherein i is a natural number between 1 and n-1 and n represents the number of pressure measuring points disposed along the longitudinal axis of the reactor and being at least equal to 3 wherein measurement point 1 is the lowest measurement point and measurement point n is the highest measurement point in said reaction section, (b) calculating a value corresponding to the difference between two consecutive pressure drops per meter divided by their mean (ΔGi+1—ΔGi)/((ΔGi+1+ΔGi)/2), for each pressure drop per meter ΔGi in the catalyst suspension in the liquid phase, (c) injecting at least one additive comprising at least one organosilicon polymer at least at the bottom of said reaction section when at least one of the values calculated in the stage (b) is greater than or equal to 5%.