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US 4,100,266 AGranted
Control system for a sulfur process
AssigneePhillips Petroleum Company
InventorDexter E. Smith
Life of this patent
Estimating the term…
Abstract
Control of a process for producing free sulfur from hydrogen sulfide is accomplished by manipulating the flow rate of a feed stream containing oxygen to a furnace in such a manner that a desired proportion of the hydrogen sulfide fed to the furnace is converted to sulfur dioxide. The flow rate of a feed stream containing hydrogen sulfide to a tail gas cleanup process is also manipulated utilizing feedforward and feedback control to maintain the hydrogen sulfide and sulfur dioxide concentrations in the gas stream from the tail gas cleanup process at acceptable levels to avoid environmental polution.
Claims25
Apparatus comprising:
- a furnace means;
- first conduit means for passing a first feed stream containing hydrogen sulfide (H.sub.2 S) into said furnace means;
- second conduit means for passing a second feed stream containing oxygen into said furnace means to convert part of the H.sub.2 S contained in the first feed stream to sulfur dioxide (SO.sub.2);
- third conduit means for withdrawing the resulting gaseous reaction mixture, containing free sulfur and unreacted H.sub.2 S and SO.sub.2 gases, from said furnace means;
- first sulfur removal means to remove at least a part of the free sulfur contained in the said gaseous reaction mixture, thereby producing a denuded gaseous stream containing unreacted H.sub.2 S and SO.sub.2 ;
- a catalytic sulfur converter means to convert a portion of the unreacted H.sub.2 S and SO.sub.2 gases contained in said denuded gaseous mixture to free sulfur;
- second sulfur removal means to remove at least a portion of the free sulfur from the resulting gaseous reaction mixture produced in said catalytic sulfur converter means, thereby producing a primary tail gas stream containing unreacted H.sub.2 S and SO.sub.2 ;
- a tail gas cleanup reactor means for further reducing the concentration of H.sub.2 S and SO.sub.2 in the primary tail gas stream from said catalytic sulfur converter means;
- fourth conduit means for passing a third feed stream containing H.sub.2 S gas into said tail gas cleanup reactor means;
- means for separating at least part of the free sulfur formed in said tail gas cleanup reactor means from the resulting reaction effluent to produce a secondary tail gas stream;
- means for establishing a first signal representative of the actual flow rate of the first feed stream flowing through said first conduit means;
- means for establishing a second signal representative of the actual flow rate of the second feed stream flowing through said second conduit means;
- means for analyzing said primary tail gas stream flowing from said second sulfur removal means to said tail gas cleanup reactor means and establishing a third signal representative of the H.sub.2 S concentration in said primary tail gas stream, a fourth signal representative of the SO.sub.2 concentration in said primary tail gas stream, and a fifth signal representative of the H.sub.2 S/SO.sub.2 ratio in said primary tail gas stream;
- means for analyzing said secondary tail gas stream and establishing a sixth signal representative of the H.sub.2 S concentration in said secondary tail gas stream and a seventh signal representative of a data ready condition;
- means for establishing an eighth signal representative of the desired H.sub.2 S/SO.sub.2 ratio in said primary tail gas stream;
- means for establishing a ninth signal representative of the required volume of said second feed stream necessary to convert a required proportion of the H.sub.2 S in a known volume of said first feed stream to SO.sub.2 ;
- means for establishing a 10th signal representative of the desired H.sub.2 S concentration in said secondary tail gas stream;
- means for producing, in response to said first, said fifth, said eighth, and said ninth signals, an 11th signal representative of the required flow rate of said second feed stream and for utilizing a comparison of said 11th signal and said second signal to manipulate the flow rate of said second feed stream;
- means for producing, in response to said first, said seventh and said tenth signals, a 12th signal representative of a feed forward control signal for the H.sub.2 S/SO.sub.2 ratio in said primary tail gas stream;
- means for producing, in response to said sixth, said seventh and said tenth signals, a 13th signal representative of a feedback control signal for the H.sub.2 S concentration in said secondary tail gas stream;
- and
- means for producing, in response to said twelfth and said thirteenth signals, a 14th signal representative of the required flow rate of the third feed stream and for utilizing said 14th signal to manipulate the flow rate of said third feed stream.
19 more elements
A method for controlling the conversion of hydrogen sulfide to sulfur, comprising the steps of:
- passing a first feed stream containing hydrogen sulfide (H.sub.2 S) into a first reaction zone;
- passing a second feed stream containing oxygen into said first reaction zone;
- in said first reaction zone, converting part of the hydrogen sulfide from said first stream to sulfur dioxide and then reacting part of the thus produced sulfur dioxide with part of the remaining hydrogen sulfide to produce free sulfur;
- passing the resulting gaseous reaction mixture containing free sulfur and unreacted hydrogen sulfide and sulfur dioxide gases from said first reaction zone to a first sulfur removal zone and therein removing at least a portion of the free sulfur contained in the mixture, thereby producing a denuded stream containing unreacted hydrogen sulfide and sulfur dioxide;
- passing said denuded stream to a catalytic sulfur converter zone and therein converting a portion of the unreacted hydrogen sulfide and sulfur dioxide gases to free sulfur;
- passing the resulting gaseous effluent from said catalytic sulfur converter zone to a second sulfur removal zone and therein removing at least a portion of the free sulfur contained in the gaseous effluent to produce a primary tail gas stream containing unreacted hydrogen sulfide and sulfur dioxide;
- passing said primary tail gas stream from said second sulfur removal zone to a tail gas cleanup reaction zone;
- passing a third feed stream containing hydrogen sulfide gas into said tail gas cleanup reaction zone and therein reacting said primary tail gas stream and said third feed stream;
- separating the resulting free sulfur produced in said tail gas cleanup reaction zone to produce a secondary tail gas stream containing the remaining unreacted hydrogen sulfide and sulfur dioxide gases;
- establishing a first signal representative of the actual flow rate of said first feed stream;
- establishing a second signal representative of the actual flow rate of said second feed stream;
- establishing a third signal representative of the hydrogen sulfide concentration in the gas mixture flowing from said second sulfur removal zone, a fourth signal representative of the sulfur dioxide concentration in the gas mixture flowing from said second sulfur removal zone, and a fifth signal representative of the H.sub.2 S/SO.sub.2 ratio in the gas mixture flowing from said second sulfur removal zone;
- establishing sixth signal representative of the hydrogen sulfide concentration in said secondary tail gas steam and a seventh signal representative of a data ready signal;
- establishing an eighth signal representative of the required H.sub.2 S/SO.sub.2 ratio in said primary tail gas stream;
- establishing a ninth signal representative of the required volume of said second feed stream necessary to convert a required proportion of the hydrogen sulfide in a known volume of said first feed stream to sulfur dioxide;
- establishing a 10th signal representative of the desired hydrogen sulfide concentration in said secondary tail gas stream;
- producing, in response to said first, said fifth, said eighth and said ninth signals, an 11th signal representative of the required flow rate of said second feed stream and utilizing a comparison of said 11th signal and said second signal to manipulate the flow rate of the said second feed stream;
- producing, in response to said first, said third, and said fourth signals, a 12th signal representative of a feed forward control signal for the H.sub.2 S/SO.sub.2 ratio in said primary tail gas stream;
- producing, in response to said sixth, said seventh, and said tenth signals, a 13th signal representative of a feedback control signal for the hydrogen sulfide concentration in said secondary tail gas stream;
- and
- producing, in response to said twelfth and said thirteenth signals, a 14th signal representative of the required flow rate of said third feed stream and utilizing said 14th signal to manipulate the flow rate of said third feed stream.
18 more elements
Dependencies are inferred from the claim text.