Method and arrangement for cleansing a flow of hot contaminated gas

Claim 3

A method according to claim 1, including the steps of further cooling the gas flow in a third stage, subsequent to extracting dust from said gas flow in said first dust separator, said gas flow being cooled in said third stage to a third temperature at which at least the major part of the gaseous contaminants present in the gas are converted to their respective liquid phases.

Claim 4

A method according to claim 2, including cooling the gas flow in the third stage alternatively in at least two parallel-connected heat exchangers.

Claim 5

A method according to claim 3, including disconnecting at least one heat exchanger and cleaning said at least one disconnected heat exchanger.

Claim 6

A method according to claim 3, characterized by cleansing the gas of contaminant condensates in a further dust separator, subsequent to further cooling the gas in said third stage.

Claim 7

A method according to claim 3, including cleansing the gas of contaminant condensates in a filter, subsequent to further cooling of the gas in said third stage, said filter being in the form of an electrostatic dust precipitator operating as a wet electrofilter.

Claim 8

A method according to claim 3, including cleansing the gas of contaminant condensates in a filter, subsequent to further cooling the gas in said third stage, said filter being an electrostatic dust precipitator for extracting dry contaminants.

Claim 9

A method according to claim 3, including cleansing the gas of contaminant condensates in a filter, subsequent to further cooling the gas in said third stage, said filter being a barrier filter.

Claim 10

A method according to claim 2, characterized by cleansing the gas of contaminant condensates in a further dust separator, subsequent to further cooling the gas in said third stage.

Claim 11

A method according to claim 9, including moderately heating the gas subsequent to passing the gas through said further dust separator, and utilizing part of the heated gas as the colder gas flow in said second cooling stage.

Claim 12

A method according to claim 2, including cleansing the gas of contaminant condensates in a filter, subsequent to further cooling of the gas in said third stage, said filter being in the form of an electrostatic dust precipitator operating as a wet electrofilter.

Claim 13

A method according to claim 11, including moderately heating the gas subsequent to passing the gas through said filter, and utilizing part of the heated gas as the colder gas flow in said second cooling stage.

Claim 14

A method according to claim 2, including cleansing the gas of contaminant condensates in a filter, subsequent to further cooling the gas in said third stage, said filter being an electrostatic dust precipitator for extracting dry contaminants.

Claim 15

A method according to claim 2, including cleansing the gas of contaminant condensates in a filter, subsequent to further cooling the gas in said third stage, said filter being a barrier filter.

Claim 16

A method according to claim 1, characterized by cooling the gas flow in said first stage to a temperature of 250°-400° C.

Claim 17

A method according to claim 1, characterized by cooling the gas flow in said second stage in a manner such that at most 10% of the gaseous contaminants present in the gas are converted to their respective liquid phases.

Claim 18

A method according to claim 1, characterized by cooling the gas flow in said second stage by supplying thereto a flow of cold, previously cleansed gas.

Claim 19

A method according to claim 1, including moderately heating the gas subsequent to passing the gas through a further dust separator, and utilizing part of the heated gas as the colder gas flow in said second cooling stage.

Claim 20

A method according to claim 18, wherein the first dust separator is a barrier filter.

Claim 21

A method according to claim 19, including further cooling the gas in a second heat exchanger subsequent to said treatment in said first dust separator.

Claim 22

A method according to claim 18, including heating wall surfaces of the second cooling stage to prevent condensation of gaseous contaminants on the wall surfaces of the second cooling stage.

Claim 23

A method according to claim 18, including forming the first dust separator as a plurality of separators connected in parallel.

Claim 24

An arrangement for improved separation of contaminants, particularly gaseous contaminants, from a flow of process gas generated in a metallurgical industrial plant and which is contaminated with solid dust particles dispersed throughout the gas flow and with gaseous combustile contaminants that are dispersed throughout said gas flow, comprising a first heat exchanger to which said flow of process gas is fed and in which the process gas is cooled to a temperature above a predetermined temperature at which the gaseous contaminants pass into liquid phases; a cooling mixer disposed downstream of and in communication with said first heat exchanger so as to receive said cooled process gas and further cool said process gas to a further temperature to condense a part of the gaseous contaminants present, the condensed contaminants being bound to said solid dust particles by at least one of an adsorption and absorption process so as to form liquid laden particles; and a first dust separator disposed downstream of and in communication with said cooling mixer so as to receive said further cooled process gas and to separate said liquid laden particles from the process gas.

Claim 25

An arrangement for improved separation of contaminants, particularly gaseous contaminants, from a flow of process gas generated in a metallurgical industrial plant and which is contaminated with solid dust particles dispersed throughout the gas flow and with gaseous combustile contaminants that are dispersed throughout said gas flow, comprising a first heat exchanger to which said flow of process gas is fed and in which the process gas is cooled to a temperature above a predetermined temperature at which the gaseous contaminants pass into liquid phases; a cooling mixer disposed downstream of and in communication with said first heat exchanger so as to receive said cooled process gas and further cool said process gas to a further temperature to condense a part of the gaseous contaminants present, the condensed contaminants being bound to said solid dust particles by at least one of an adsorption and absorption process so as to form liquid laden particles; and a first dust separator disposed downstream of and in communication with said cooling mixer so as to receive said further cooled process gas and to separate said liquid laden particles from the process gas.

Claim 26

An arrangement according to claim 23, wherein a second heat exchanger is disposed downstream of and in communication with said first dust separator further cool said process gas to a temperature at which at least the major part of the gaseous contaminants pass into their respective liquid phases.

Claim 27

An arrangement according to claim 24, the second heat exchanger comprises one or more heat exchangers connected in parallel.

Claim 28

An arrangement according to claim 24, comprising a further dust separator disposed downstream of and in communication with said second heat exchanger so as to cleanse said process gas of condensed contaminants subsequent to passing from the second heat exchanger.