FIELD: oil and gas industry.
SUBSTANCE: present invention relates to the field of catalytic cracking of petroleum fractions. Method for catalytic cracking of heavy hydrocarbon fractions of the VGO type or atmospheric distillation residue using a fluidised bed catalytic cracking unit comprising a reaction section operating in an upstream or downstream mode, and a catalyst regeneration section that burns coke deposited on the catalyst in the reaction section with combustion air, preliminarily compressed using a MAB (main air blower) compressor, wherein said regeneration section regenerates regenerator flue gases, which carry out heat exchange in a waste heat boiler (WHB) before entering the electrostatic precipitator (ESP), then into the economiser (ECO), wherein said method also uses a heat exchanger which enables to produce high pressure (HP) steam due to the heat introduced by the regenerated catalyst, said heat exchanger is referred to as a "catcooler" (catalyst cooler), wherein the method is characterised in that said combustion air is preheated downstream of the MAB compressor to a temperature of 200–350 °C, preferably up to 250–200 °C, in an APH heat exchanger with flue gases with regeneration located downstream of the WHB and upstream of the economiser (ECO) wherein the temperature of the flue gases collected at that point ranges from 300 to 650 °C, wherein excess heat introduced by the combustion air is converted into high-pressure steam (from 45 to 100 bar, preferably from 50 to 70 bar) at the level of the external heat exchanger (catcooler) on the hot catalyst taken in the regenerator. Also disclosed is a version of the catalytic cracking method of heavy hydrocarbon fractions such as VGO or atmospheric distillation residue using a fluidised bed catalytic cracking unit, wherein said method does not use a heat exchanger of the "catcooler" type, and this method differs in that the combustion air is preheated downstream of the MAB compressor to a temperature of 200–350 °C, preferably up to 250–300 °C, in an APH heat exchanger with regeneration flue gases located downstream the WHB and upstream of the economiser (ECO), wherein the temperature of the flue gases collected at that point ranges from 300 to 650 °C, and the excess heat introduced by the combustion air reduces the fuel consumption in the preheating furnace of said combustion air.
EFFECT: improved energy efficiency of the unit.
6 cl, 4 ex, 2 dwg
