The polypropylene plant has a design capacity of 1280,000 TPY. It contains (4) reaction trains, each of which has capacity of 32,000 TPY. The reaction area consists of four reactor trains. (3) of the (4) trains have two reactors, (1) primary and (1) secondary each. One train has only (1) primary reactor. Propylene, ethylene and other comonomers are fed into the reactor(s). Hydrogen is added to control the molecular weight. The reaction is exothermic. Reactor cooling is achieved by evaporation of liquefied reactor gas, which is injected into the reactor. Flash evaporation of the liquid in the polymer bed ensures the most efficient heat removal. The polymer powder is discharged from the reactor(s) and separated from the gas in a discharge cyclone at atmospheric pressure. Any unreacted monomer separated from the powder is compressed and either recycled or returned to the upstream olefins unit for recovery.