Patent ID: 6996989

Claim:
A process to recover energy from a hot gas, obtained from a smelting reduction process used to continuously prepare steel, wherein the hot gas has 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 hot gas to provide a cooled gas having a temperature of below 550° C. by means of a shell-tube heat exchanger, wherein the hot gas is passed at the shell side of the shell-tube heat exchanger and coolant water is passed at the tube side of the shell-tube heat exchanger, wherein steam is formed, from which steam energy is recovered, and wherein the shell-tube heat exchanger includes an elongated membrane wall formed by a plurality of elongated tubes connected together so as to form the elongated membrane wall, wherein the elongated membrane wall further defines a tubular space having at one end of the tubular space an inlet opening for receiving the hot gas into the tubular space and at an opposite end of the tubular space an outlet opening for discharging the cooled gas from the tubular space, wherein a plurality of heat exchanging tubes providing the tube side of the shell-tube heat exchanger that pass through the tubular space thereby defining a plurality of channels for the passage of the hot gas within the tubular space and between the plurality of heat exchanging tubes, (b) separating the particles from the cooled gas by means of one or more sequentially arranged centrifugal separation devices to a dust level of below 400 mg/Nm3 to give a reduced dust gas, (c) expanding the reduced dust gas in an expander to recover energy.