Process to recover energy from hot has

A process to recover energy from a gas, obtained from a smelting reduction process used to continuously prepare steel, having a temperature of above 650° C. and an absolute pressure of more than 1.7 bar and comprising non-solidified alkali containing compounds and particles by performing the following steps:

• (a) cooling the gas to a temperature of below 550° C. by means of a shell-tube heat exchanger, wherein the hot gas is passed at the shell side and coolant water is passed at the tube side, wherein steam is formed, from which steam energy is recovered, and wherein the shell-tube heat exchanger comprises a membrane wall positioned in an elongated vessel, which elongated membrane wall is open at either side for gas to enter and leave the inner part of the space surrounded by said membrane wall, which inner space is provided with a plurality of heat exchanging tubes, which tubes are interconnected at their exterior in a group wise manner and positioned in said inner space such that a plurality of channels for passage of hot gas exist, which passages run parallel to the elongated walls of the membrane wall,
• (b) separating the particles from the gas by means of one or more sequentially arranged centrifugal separation devices to a dust level of below 400 mg/Nm3,
• (c) expanding the gas in an expander to recover energy.