GB1441552A - Heat exchange system for cooling hot dust-laden gases - Google Patents

Abstract

1441552 Gas cooling installations; tubular heat exchangers AMAX Inc 6 Nov 1974 [7 Jan 1974] 48030/74 Heading F4S Hot flue gas. having an elevated dew point (e.g. from a molybdenum sulphide roaster) is cooled in a heat exchanger 10, 10A by an air stream circulated in a substantially closed circuit, Fig. 3, and having its temperature controlled so as to maintain the temperature of the heat exchange surfaces in contact with the flue gas above the dew point temperature of said gas. The heat exchanger, Fig. 2, comprises concentric-tube elements 12, 15 or 12A, 15A with the hot gas flowing through the inner tubes and the coolant air flowing between the tubes of each element. As shown the heat exchanger comprises two element groups each in its own casing 11, 11A. The casings provide an insulating air blanket around individual elements. On the gas side the respective groups of tubes 12, 12A are interconnected by a duct 19, and on the air side the respective groups of tubes 15, 15A are interconnected by a duct 20. Expansion joints are indicated at 23, 23A, 24 and 24A; and 25 denotes heat insulation at the ends of the heat exchanger tubes 12 or 12A. In the circuit shown in Fig. 3 the coolant air is circulated by a blower B2 and the hot gas flow is maintained by a blower B-1. The quantity of air flowing is controlled by a valve V-2 in response to the flue gas temperature downstream of the heat exchangers 10, 10A as sensed by a device TC-1. A device TC-2 senses the heat exchange surface temperature on the flue gas side (e.g. at a point 31 located at the inlet of the heat exchanger or alternatively at the outlet end of the heat exchanger) and regulates the circulating air temperature by opening more or less a fresh air inlet valve V-1, at the same time closing or opening a linked valve V-4 in the circuit. An excess of air pressure in the circuit is relieved by a valve V-3 opening or closing in response to a controller PC-3. V-5 is a manually operated valve used to set a predetermined air flow in the circuit below which the flow rate is automatically regulated by the control means TC-1 &c. in the circuit. A heater H-1 is provided for heating the air during the starting-up period TI-1 is an indicator for surface temperature at the point 31A. TI-2 and TI-3 are indicators providing a check on the temperature of the circulating air- All components of the circuit may be heat insulated.