NOVELTY - A process for the densification of particulate solids (P), especially biomass, with a view to the production of pyrolysis oil for use, e.g. as fuel, involves heating and drying, flash pyrolysis in a sealed reactor with a screw conveyor or heated vibrating tube, extraction and rapid condensation of pyrolysis gases in a vertical condenser and recovery of pyrolysis oil from the bottom of the condenser.    USE - Pyrolysis oils obtained by this process are used in energy-related applications, e.g. as fuel for heating or in heat engines, for green chemistry or for fractionation etc.    ADVANTAGE - Enables the conversion of solid biomass particles under conditions favorable to pyrolysis, with high process yields, i.e. 50-80% oil of high calorific value (4000-7000 kcal/kg), and under optimum conditions with regard to energy consumption, pollution and simplicity of operation.    DETAILED DESCRIPTION - A process for the energetic densification of products (P) in the form of divided solids, especially biomass, with a view to the production of pyrolysis oils for energy-related applications, involves (a) preconditioning (P) by heating and drying to about 100 degrees C and not more than about 10% RH, (b) flash pyrolysis by circulation in a sealed reactor containing at least one screw conveyor or a vibrating tube (22) heated by the Joule effect so that the product is heated to 400-850 degrees C with a residence time of between a few seconds and a few minutes, (c) extraction of the pyrolysis gases at the top of the reactor (20) followed by rapid condensation in a vertical condenser (30) and (d) recovery of the pyrolysis oils from the bottom of the condenser (30). An INDEPENDENT CLAIM is also included for an installation for use in the above process, comprising a preconditioner (10; 60) for heating and drying as above, a pyrolysis reactor (20) connected to the preconditioner outlet and fitted with a conveyor screw or a heated vibrating tube (22), and a vertical condenser (30) with its inlet connected to an outlet (31) from the reactor (20) and fitted with a bottom outlet (35) for the condensed oils obtained.    DESCRIPTION OF DRAWING(S) - The drawing shows one version of an installation for the process according to the invention.    preconditioner (10)    double jacketed channel (11)    screw conveyor (12)    feed hopper (15)    vapor outlet (17)    pyrolysis reactor (20)    closed reactor chamber (21)    screw conveyor (22)    gate valve (23)    gas injection pipe (29)    vertical condenser (30)    outlet tap (31)    connecting pipe with means of maintaining a constant temperature (32, 33)    condenser tubes (34)    furnace (36)    outlet and pipe for non-condensable fractions (37, 38)    extractor fan (38.1)    trap for oil droplets (39)    sealed cooler (40)    residual coke (50)    powdered solid biomass (P)    pyrolysis oil. (B)