Abstract: A process of removing SO.sub.x from a gas stream using a fluidized bed having a mixing chamber at the lower end for mixing the gas with CaCO.sub.3, causing the gas-carbonate reaction product to rise while being cooled. Solids caught in the cyclone are separated and returned to the mixing chamber for re-use.

Abstract: Dynamic fluidized-bed reactor for carrying out a chemical or physical multi-component process, which said reactor comprises a preferably vertical, cooled or uncooled reactor chamber and a preferably horizontal cyclone that discharges the solid matter through the side of the separator chamber and the gases through one end or both ends of the separator chamber. The reactor further comprises a discharge pipe with no gas lock, which allows the solid matter to fall freely. In different applications, the reactor may include feed and discharge means for solid matter as well as a gas distributor grate. Exemplifying embodiments are a fire-tube boiler and a reactor for purification and cooling of hot gases.