US3908969A — Method and apparatus for air pollution control co…

Claim 1

Independent Claim 294 words

For use in a system for air pollution control and safe gas recovery and control of hot off-gases from a bottom blown oxygen steelmaking converter vessel utilizing injection of hydro-carbon fluid, as means to prevent bottom refractory deterioration along with process oxygen and other inert gases together with entrained finely divided materials beneath the surface of molten metal for converting ferrous metal to steel, the improvement comprising: a. said bottom blown oxygen vessel having a mouth opening and a water-cooled hood means with an inside diameter essentially equal to the vessel mouth opening, b. said water-cooled hood means having a movable skirt means advanceable and retractable to adjust and vary an air gap between said hood means and vessel mouth opening, c. said water-cooled hood means being connected through a watercooled stack means to a water-cooled duct means connected to a first venturi-scrubber for quenching hot gases and initial precleaning, d. said first venturi-scrubber being connected through ducting to a secondary wet venturi-scrubber for final cleaning, e. said second venturi-scrubber means being provided with a fixed whirl vane separator for removing entrapped water particles from the gas stream, said gas stream being made to change direction and discharge tangentially to a duct leading to an exhaust fan, f. said exhaust fan having an operating characteristic that provides an essentially constant pressure over a wide range of gas flow rates and a pressure outlet for discharging clean waste gases into a stack, g. said waste gas stack having two outlets, a shut-off valve in each of said outlets, one of said stack outlets being provided with a torch to burn cleaned waste gases for discharge to the atmosphere, the other of said stack outlets being adapted for connection to a storage reservoir for gas storage.

Claim 2

Dependent Claim 294 words

For use in a system for air pollution control and safe gas recovery and control of hot off-gases from a bottom blown oxygen steelmaking converter vessel utilizing injection of hydro-carbon fluid, as means to prevent bottom refractory deterioration along with process oxygen and other inert gases together with entrained finely divided materials beneath the surface of molten metal for converting ferrous metal to steel, the improvement comprising: a. said bottom blown oxygen vessel having a mouth opening and a water-cooled hood means with an inside diameter essentially equal to the vessel mouth opening, b. said water-cooled hood means having a movable skirt means advanceable and retractable to adjust and vary an air gap between said hood means and vessel mouth opening, c. said water-cooled hood means being connected through a watercooled stack means to a water-cooled duct means connected to a first venturi-scrubber for quenching hot gases and initial precleaning, d. said first venturi-scrubber being connected through ducting to a secondary wet venturi-scrubber for final cleaning, e. said second venturi-scrubber means being provided with a fixed whirl vane separator for removing entrapped water particles from the gas stream, said gas stream being made to change direction and discharge tangentially to a duct leading to an exhaust fan, f. said exhaust fan having an operating characteristic that provides an essentially constant pressure over a wide range of gas flow rates and a pressure outlet for discharging clean waste gases into a stack, g. said waste gas stack having two outlets, a shut-off valve in each of said outlets, one of said stack outlets being provided with a torch to burn cleaned waste gases for discharge to the atmosphere, the other of said stack outlets being adapted for connection to a storage reservoir for gas storage.

Claim 3

Dependent Claim 146 words

The apparatus set forth in claim 1 wherein: a. motive means is provided for raising and lowering said skirt in response to signals from a partial oxygen pressure sensor for assuring safe closure of the hood based on indication of stoichiometric combustion point of formation of an inert plug, b. said first venturi-scrubber being equipped with a variable throat operated by a motor, said throat being constructed and arranged to close down from a full open position to a pre-set minimum opening established through the use of conventional limit switches, c. said second venturi-scrubber being equipped with a motor operated variable throat, said throat being constructed and arranged to open to a pre-set minimum value based on signals from a set point indicator, and additionally provided for operation to control flow rate on the basis of hood pressure control and signals from a gas analysis system.

Claim 4

Dependent Claim 166 words

The apparatus set forth in claim 2 including: a. control means for controlling the position of said moveable hood skirt with respect to vessel mouth firstly at a period in the heat cycle when an inert gas plug has formed and purged the gas cleaning system of combustion air to ensure safe passage of combustible gas through said gas cleaning system, and for establishing an air gap size that provides a negative pressure equal to a pre-set value set into a pressure set value indicator, b. said control means being operable in response to control signals from a oxygen partial pressure sensor which indicates that a stoichiometric combustion point has been reached and that an inert gas plug has been formed; and a pressure sensor coupled to the hood for producing a signal to stop hood skirt downward movement based on arrival of a null point equating a pre-set negative pressure reading with an actual pressure drop value in the hood measured by said pressure sensor.

Claim 5

Dependent Claim 197 words

The apparatus set forth in claim 2 including: a. control means effective for opening and closing of the variable throat of the said secondary venturi scrubber, such that the throat opening will vary as a function of the gas evolved from the bath of said bottom blown oxygen converter process vessel, b. said control means including pressure measuring means for measuring the pressure in the substantially closed hood and for producing an electrical signal, regulator means coupled to receive said signal for comparing said signal to a pre-set negative pressure value, said regulator means being responsive to said comparison for actuating the first venturi throat operating motor, c. an infra-red sensor associated with said oxygen partial pressure sensor means for measuring the CO, CO2 and H2O, exhausting from said vessel such that in combination a direct measurement of gas calorific value is obtained and used to supervise the pre-set pressure value in the pressure control system in relation with a pre-set required gas calorific value for collection, d. the said pressure control supervision means being obtained by varying the manually pre-set negative pressure set value in the range minus 1 mm to minus 10 mm water column.

Claim 6

Dependent Claim 46 words

The invention set forth in claim 4 wherein: a. The adjustment of the system to obtain the range of said negative pressure set values being achieved through independent movements of either the said hood skirt or said variable venturi throat, or through a combination of both.

Claim 7

Dependent Claim 92 words

The invention set forth in claim 4 wherein: a. the said calorific value measurement signal from a combination of said oxygen partial pressure sensor and said infra-red sensor being for controlling the switching of off-gas from exhaust to collection in reference with a desired calorific value pre-set into a set value indicator, b. said oxygen partial pressure sensor being coupled to sample said gas at one of said water-cooled hood on the raw gas side adjacent said converter mouth opening and subsequent to the first venturi scrubber on the precleaned gas side.

Claim 8

Dependent Claim 177 words

The apparatus set forth in claim 1 wherein: a. said vessel including a position indicator to indicate degree of tilt of said vessel from vertical, a nitrogen injection valve means coupled to a source of nitrogen gas and one of said vessel bottom tuyeres and hood means, the said position indicator being electro-mechanically coupled to operate the nitrogen injection valve means for injection of inertization nitrogen into the said one of said vessel bottom tuyeres and, b. gas analysis means coupled to measure the calorific value of said off gases and for providing a signal in response thereto, c. said nitrogen injection valve means being controlled by said signal from the gas analysis means such that a direct calorific value reading will trigger injection of nitrogen in the hood for inertization where the bottom blown vessEl is turned down, c. said nitrogen injection valve means being operable during the operation of a blow when the presence of oxygen in the system is signaled by the gas analysis means simultaneously at a pre-set figure for gas calorific value.

Claim 9

Dependent Claim 101 words

The apparatus set forth in claim 1 including: a. An auxiliary hood means located on one of the charging or tapping sides of the bottom blown oxygen converter vessel to collect fumes during such periods when the vessel is tilted from a vertical position and is nonconicident with the water-cooled hood means, b. said auxiliary hood means being connected through a duct means to the inlet of the said secondary venturi scrubber means, c. said duct means being provided with a shut-off valve to progressively switch from a fully closed to a fully open position as the vessel means is tilted.

Claim 10

Dependent Claim 52 words

The invention set forth in claim 8 wherein: said vessel position indicator means is coupled to said shut-off valve to said first venturi throat means for progressively and simultaneously close the said first venturi throat means up to a preset minimum opening and to open said auxiliary hood system shut-off valve means.

Claim 11

Dependent Claim 86 words

The invention set forth in claim 9 wherein: a. the main gas cleaning system includng said water-cooled hood means, venturi scrubber means, and exhaust fan are used along with said auxiliary hood means to collect and clean fumes when said vessel is tilted from a vertical blowing position, b. said fumes collected in the auxiliary hood means being cleaned in the said second venturi scrubber means, and the fumes collected in the water-cooled hood means being cleaned both in the first and second venturi scrubber means.

Claim 12

Independent Claim 330 words

A system for collecting off-gases from a bottom-blown vessel in which molten ferrous metal is converted to steel, said vessel having a mouth through which the gases exit from the vessel, comprising: a. gas collection hood means situated over the mouth of the vessel at the beginning of a gas flow path and including skirt means that are advanceable and retractable to permit varying the gap between the vessel mouth and the hood means, b. first venturi-scrubber means having an inlet and an outlet, and first duct means connecting said inlet to said hood means, said first venturi-scrubber means including means for regulating gas flow therethrough, c. second venturi-scrubber means having an inlet and an outlet, and second duct means connecting said inlet to said outlet of said first scrubber means, said second scrubber means including means for regulating gas flow therethrough selectively whereby to permit regulation of the gas pressure in said hood means, d. exhaust fan means having an inlet connected to said second scrubber means outlet and also having an outlet, said exhaust fan being characterized by producing a substantially constant pressure on its inlet side for a wide range of gas flow rates, e. partial pressure sensor means disposed in the gas flow path, said partial pressure sensor means producing signals which are functionally related to combustibility of said gases, f. means operatively coupled with said skirt means for positioning it to create a desired gap between the skirt means and the vessel mouth, said operatively coupled means being controlled on at least one occasion by said signals, g. said operatively coupled means responding to a purging inert gas plug being formed, as indicated by said sensor means sensing that substantially stoichiometric combustion of the gases has occured, by advancing said skirt means to reduce the gap between the skirt means and the vessel mouth whereupon air flow through said gap and gas flow through the system in under control of said gas flow regulating means.

Claim 13

Independent Claim 330 words

A system for collecting off-gases from a bottom-blown vessel in which molten ferrous metal is converted to steel, said vessel having a mouth through which the gases exit from the vessel, comprising: a. gas collection hood means situated over the mouth of the vessel at the beginning of a gas flow path and including skirt means that are advanceable and retractable to permit varying the gap between the vessel mouth and the hood means, b. first venturi-scrubber means having an inlet and an outlet, and first duct means connecting said inlet to said hood means, said first venturi-scrubber means including means for regulating gas flow therethrough, c. second venturi-scrubber means having an inlet and an outlet, and second duct means connecting said inlet to said outlet of said first scrubber means, said second scrubber means including means for regulating gas flow therethrough selectively whereby to permit regulation of the gas pressure in said hood means, d. exhaust fan means having an inlet connected to said second scrubber means outlet and also having an outlet, said exhaust fan being characterized by producing a substantially constant pressure on its inlet side for a wide range of gas flow rates, e. partial pressure sensor means disposed in the gas flow path, said partial pressure sensor means producing signals which are functionally related to combustibility of said gases, f. means operatively coupled with said skirt means for positioning it to create a desired gap between the skirt means and the vessel mouth, said operatively coupled means being controlled on at least one occasion by said signals, g. said operatively coupled means responding to a purging inert gas plug being formed, as indicated by said sensor means sensing that substantially stoichiometric combustion of the gases has occured, by advancing said skirt means to reduce the gap between the skirt means and the vessel mouth whereupon air flow through said gap and gas flow through the system in under control of said gas flow regulating means.

Claim 14

Dependent Claim 23 words

The system set forth in claim 11 wherein: a. said sensor means is responsive to the partial pressure of oxygen in said gases.

Claim 15

Dependent Claim 83 words

The system set forth in claim 11 including: a. second sensor means disposed In the gas flow path, said second sensor means producing signals which are functionally related to the content of gases selected from the class of CO, CO2, and H2O and combinations thereof, b. control means responsive to said last named signals and coordinately controlling said gas flow regulator means to maintain negative pressure in said hood means when said skirt means is advanced to reduce the gap with said vessel.

Claim 16

Dependent Claim 18 words

The invention set forth in claim 13 wherein: a. said second sensor means is an infrared type sensor.

Claim 17

Dependent Claim 103 words

The system set forth in claim 11 including: a. means for presetting a set point for a first predetermined preferably negative pressure that is to be effected by said second venturi-scrubber means, and first control means controlling the flow regulating means of said second scrubber means, b. pressure sensor means sensing pressure in said hood means at least when said skirt means has reduced said gap, said pressure sensor means producing control signals to which said control means responds by maintaining the desired negative pressure in said hood means to provide finer operational gas flow corrections when said hood means gap is reduced.

Claim 18

Dependent Claim 97 words

The system set forth in claim 15 including: a. means for presetting a second set point pressure, which when attained in said hood means effects interruption of the advance of said skirt means toward said vessel, said aforesaid pressure sensor means in said hood means producing a signal which is functionally related to the actual pressure in said hood means, and b. means for comparing said last named produced signal and said second set point pressure to thereby produce a signal for controlling the aforesaid first control means to thereafter regulate the pressure in said hood means.

Claim 19

Dependent Claim 43 words

The system set forth in claim 15 wherein: a. the value of said preset first set point is adjusted to maintain the negative pressure in said hood means in the range of 1 millimeter to 10 millimeters in terms of a water column.

Claim 20

Dependent Claim 150 words

The system set forth in claim 11 including: a. second sensor means disposed in the gas flow path from said vessel, and producing signals which are functionally related to the content of gases selected from the class of CO, CO2, and H2O and combinations thereof, b. individual valve means selectively operable to direct said gases alternatively to an exhaust path or a collection path, c. valve control means operatively associated with said valve means, d. means for presetting the values of at least the CO and CO2 which shall exist when said valve means are operated to collect said gases, e. means comparing the signals corresponding to gas analysis made by said second sensor means with the values of said last named presetting means, the said control means responding to said comparison by selectively operating said valve means whereby to determine the portion of the total gases which are collected.

Claim 21

Dependent Claim 64 words

The system set forth in claim 11 including: a valve means adapted to receive inert gas under pressure and including means associated with said valve means for injecting inert gas into the gas flow path to inertize the gases therein, b. signal operative control means operatively coupled with said last named valve means to open and close the same for selective inert gas injection.

Claim 22

Dependent Claim 72 words

The system set forth in claim 19 wherein: a. said signal operated control means is operated in response to signals from the aforesaid partial pressure sensor means, b. the said partial pressure sensor means is adapted to sense the partial pressure of oxygen when said vessel is being bottom-blown, signals corresponding with approach of enough oxygen to cause combustion causing said control means to operate said valve means for inert gas injection.

Claim 23

Dependent Claim 102 words

The system set forth in claim 20 including: a. second sensor means disposed in the gas flow path from said vessel and producing signAls which are functionally related to the content of gases selected from the class of CO, CO2 and H2O and combinations thereof, said last named signals varying in accordance with the calorific value of said gases, b. said signal operative control means receiving said last named signals concurrently with said oxygen corresponding signals whereby to operate said valve means open to thereby inject inert gas if said signals correspond with oxygen and the calorific value departing from preset values.

Claim 24

Dependent Claim 130 words

The system set forth in claim 11 including: a. an auxiliary hood means adjacent said aforementioned hood means and adapted to collect emissions from the vessel when the latter is not aligned with said aforementioned hood means, b. duct means connecting said auxiliary hood means to the inlet side of said second venturi-scrubber means and valve means in the last named duct means, c. drive means operatively coupled with said last named valve means, d. means responsive to the position of said vessel and controlling said drive means in correspondence with said position to thereby operate said last named valve means for progressively diverting gases from said hood means through said auxiliary hood means to said second venturi-scrubber as said vessel tilts out of alignment with the aforementioned hood means.

Claim 25

Dependent Claim 59 words

The system set forth in claim 22 including: a. operating means coupled with the said first venturi-scrubber gas flow regulating means, b. said means responsive to the position of said vessel controlling said operating means to thereby adjust said regulating means and the gas flow through said first venturi-scrubber means concurrently with operation of said last named valve means.

Claim 26

Independent Claim 252 words

A system for collecting off-gases from a pneumatic metallurgical converter vessel, said vessel having a mouth through which the gases exit from the vessel, comprising: gas collection hood means situated over the mouth of the vessel and including skirt means advanceable and retractable to permit varying the gap between the vessel mouth and the hood means, first and second interconnected gas cleaning means connected to said hood means and including gas flow regulating means, exhaust means having an outlet and an inlet connected to said second gas cleaning means, said hood means, said gas cleaning means and said exhaust means defining a gas flow path, gas composition sensing means coupled to said gas flow path, said sensing means being operative to produce signals which are functionally related to combustibility of said gases, skirt positioning means operatively coupled to said skirt means for positioning the same to create a desired gap between the skirt means and the vessel mouth, said skirt positioning means being at least partially controlled by said signals, said gas composition sensing means being operative to produce a predetermined signal in response to a purging inert gas plug being formed indicating that substantially stoichiometric combustion of the gases has occurred, said skirt positioning means being operative in response to said predetermined signal to advance said skirt means to reduce the gap between the skirt means and the vessel mouth whereupon air flow through said gap and gas flow through the system is under control of said gas flow regulating means.

Claim 27

Independent Claim 252 words

A system for collecting off-gases from a pneumatic metallurgical converter vessel, said vessel having a mouth through which the gases exit from the vessel, comprising: gas collection hood means situated over the mouth of the vessel and including skirt means advanceable and retractable to permit varying the gap between the vessel mouth and the hood means, first and second interconnected gas cleaning means connected to said hood means and including gas flow regulating means, exhaust means having an outlet and an inlet connected to said second gas cleaning means, said hood means, said gas cleaning means and said exhaust means defining a gas flow path, gas composition sensing means coupled to said gas flow path, said sensing means being operative to produce signals which are functionally related to combustibility of said gases, skirt positioning means operatively coupled to said skirt means for positioning the same to create a desired gap between the skirt means and the vessel mouth, said skirt positioning means being at least partially controlled by said signals, said gas composition sensing means being operative to produce a predetermined signal in response to a purging inert gas plug being formed indicating that substantially stoichiometric combustion of the gases has occurred, said skirt positioning means being operative in response to said predetermined signal to advance said skirt means to reduce the gap between the skirt means and the vessel mouth whereupon air flow through said gap and gas flow through the system is under control of said gas flow regulating means.

Claim 28

Dependent Claim 24 words

The system set forth in claim 24 wherein said gas composition sensing means is responsive to the partial pressure of oxygen in said gases.

Claim 29

Dependent Claim 83 words

The system set forth in claim 24 and including second sensor means disposed in the gas flow path, said second sensor means producing signals which are functionally related to the content of gases selected from the class of CO, CO2, and H2O and combinations thereof, and control means responsive to said last named signals and coordinately controlling said gas flow regulator means to maintain negative pressure in said hood means when said skirt means is advanced tO reduce the gap with said vessel.

Claim 30

Dependent Claim 111 words

The system set forth in claim 24 including means for presetting a set point for a first predetermined preferably negative pressure that is to be effected by said gas flow regulating means, and first control means for controlling said gas flow regulating means, and pressure sensor means coupled to said hood means and to said first control means for sensing pressure in said hood means when said skirt means has reduced said gap, said pressure sensor means producing control signals to which said first control means responds by maintaining the desired negative pressure in said hood means to provide finer operational gas flow corrections when said hood means gap is reduced.

Claim 31

Dependent Claim 91 words

The system set forth in claim 24 including means for presetting a second set point pressure, which when attained in said hood means effects interruption of the advance of said skirt means toward said vessel, said aforesaid pressure sensor means producing a signal which is functionally related to the actual pressure in said hood means, and means for comparing said last named produced signal and said second set point pressure to thereby produce a signal for controlling the aforesaid first control means to thereafter regulate the pressure in said hood means.

Claim 32

Dependent Claim 42 words

The system set forth in claim 27 wherein the value of said preset first set point is adjusted to maintain the negative pressure in said hood means in the range of 1 millimeter to 10 millimeters in terms of a water column.

Claim 33

Dependent Claim 60 words

The system set forth in claim 24 including valve means adapted to receive inert gas under pressure and including means associated with said valve means for injecting inert gas into the gas flow path to inertize the gases therein, signal operative control means operatively coupled with said valve means to open and close the same for selective inert gas injection.

Claim 34

Dependent Claim 77 words

The system set forth in claim 30 wherein said signal operated control means is operated in response to signals from the aforesaid partial pressure sensor means, the said gas composition sensing means is adapted to sense the partial pressure of oxygen when said vessel is being bottom-blown and for producing signals functionally related thereto, signals corresponding with approach of enough oxygen to cause combustion causing said control means to operate said valve means for inert gas injection.

Claim 35

Dependent Claim 100 words

The system set forth in claim 31 including second sensor means disposed in the gas flow path from said vessel and producing signals which are functionally related to the content of gases selected from the class of CO, CO2 and H2O and combinations thereof, said last named signals varying in accordance with the calorific value of said gases, said signal operative control means receiving said last named signals concurrently with said oxygen related signals whereby to operate said valve means open to thereby inject inert gas if said signals correspond with oxygen and the calorific value departing from preset values.

Claim 36

Dependent Claim 218 words

The system set forth in claim 24 including an auxiliary hood means adjacent said gas collection hood means and adapted to collect emissions from the vessel when the latter in not aligned with said gas collection hood means, said gas cleaning means including series connected first and second gas cleaning sections each having an inlet and an outlet, duct means connecting said auxiliary hood means to the inlet side of said second gas cleaning section and valve means in the last named duct means, drive means operatively coupled with said last named valve means, means responsive to the position of said vessel and controlling said drive means in correspondence with said position to thereby operate said last named valve means for progressively diverting gases from said gas collection hood means through said auxiliary hood means to the inlet of said second gas cleaning section as said vessel tilts out of alignment with the gas collection hood means. 34. The system set forth in claim 33 wherein operating means is coupled with the said gas cleaning section gas flow regulating means, said means responsive to the position of said vessel controlling said operating means to thereby adjust said gas regulating means and the gas flow through said first venturi-scrubber means concurrently with operation of said last named valve means.

Claim 37

Dependent Claim 80 words

The system set forth in claim 24 wherein one of said gas cleaning means includes wet scrubber means having an inlet connected to said hood means and an outlet connected to said exhaust means, said wet scrubber means including means for selectively regulating gas flow therethrough to permit regulation of gas pressure in said hood means, said exhaust means being constructed and arranged to provide a substantially constant pressure at its inlet for a wide range of gas flow rates.

Claim 38

Dependent Claim 31 words

The system set forth in claim 35 wherein said first and second gas cleaning includes first and second wet scrubber means connected in series and each including gas flow regulating means.

Claim 39

Dependent Claim 246 words

In combination, a metallurgical converter vessel having an opening and means for injecting process gases into molten metal containable therein, means for tilting said vessel from a first process gas blowing position to alternate positions for receiving and discharging metal, gas collection hood means disposed above the opening in said vessel when the latter is in its first position and including skirt means advanceable and retractable to permit varying the gap between the vessel opening and the hood means, first gas cleaning means, means having an inlet connected to said hood means and an outlet, said first gas cleaning means including wet scrubber means and gas flow control means for regulating the gas flow therethrough, second gas cleaning means including an inlet connected to the outlet of said first gas cleaning means and an outlet, exhaust means connected to the outlet of said second gas cleaning means, an auxiliary hood means adjacent said gas collecting hood means and adapted to collect emissions from the vessel when the latter is tilted to an alternate position, duct means connecting said auxiliary hood means to the inlet of said second cleaning means and valve means connected in said duct means, valve operator means for operating said valve means to connect said auxiliary hood means to said second gas cleaning means when said vessel is tilted to its alternate position and for closing said valve means to prevent the inflow of air when said vessel is in its first position.

Claim 40

Dependent Claim 246 words

In combination, a metallurgical converter vessel having an opening and means for injecting process gases into molten metal containable therein, means for tilting said vessel from a first process gas blowing position to alternate positions for receiving and discharging metal, gas collection hood means disposed above the opening in said vessel when the latter is in its first position and including skirt means advanceable and retractable to permit varying the gap between the vessel opening and the hood means, first gas cleaning means, means having an inlet connected to said hood means and an outlet, said first gas cleaning means including wet scrubber means and gas flow control means for regulating the gas flow therethrough, second gas cleaning means including an inlet connected to the outlet of said first gas cleaning means and an outlet, exhaust means connected to the outlet of said second gas cleaning means, an auxiliary hood means adjacent said gas collecting hood means and adapted to collect emissions from the vessel when the latter is tilted to an alternate position, duct means connecting said auxiliary hood means to the inlet of said second cleaning means and valve means connected in said duct means, valve operator means for operating said valve means to connect said auxiliary hood means to said second gas cleaning means when said vessel is tilted to its alternate position and for closing said valve means to prevent the inflow of air when said vessel is in its first position.

Claim 41

Dependent Claim 42 words

The system set forth in claim 37 and including operating means coupled to said valve means and to the gas flow control means for controlling the gas flow through said first gas flow control means concurrently with operation of said valve means.

Claim 42

Dependent Claim 137 words

The system set forth in claim 38 wherein said valve operator means includes drive means operatively coupled to said valve means, vessel position responsive means coupled to said drive means for controlling said drive means in correspondence with said position to thereby place said valve means in an open position when said vessel is in an alternate position and to place said valve means in a closed position when said vessel is in its first position for diverting gases from said gas collecting hood means through said auxiliary hood means to said second gas cleaning means when said vessel is tilted out of alignment with the gas collection hood means, said operating means also being connected to said vessel position responsive means for controlling said gas flow control means in relation to the position of said vessel.

Claim 43

Dependent Claim 40 words

The system set forth in claim 39 wherein said vessel position responsive means is operative to progressively open said valve means and reduce the flow through said first gas cleaning means as said vessel is tilted toward an alternate position.

Claim 44

Dependent Claim 17 words

The system set forth in claim 40 wherein said first and second gaS cleaning means includes venturi-scrubbers.

Claim 45

Independent Claim 317 words

A system for collecting off-gases from a pneumatic metallurgical converter vessel, said vessel having an opening through which the gases exit from the vessel, gas collection hood means situated over the opening of the vessel and including skirt means advanceable and retractable to permit varying the gap between the vessel opening and the hood means, means for tilting said vessel between a first position wherein said hood is disposed above said opening and a second position wherein said vessel is oriented with said opening displaced from alignment with said hood, first venturi-scrubber means having an inlet connected to said hood and an outlet, said first venturi-scrubber means including means for regulating gas flow therethrough. second venturi-scrubber means having an inlet connected to the outlet of said first venturi-scrubber and an outlet, said second scrubber means including means for regulating gas flow therethrough selectively whereby to permit regulation of the gas pressure in said hood means, exhaust means having an inlet connected to the outlet of said second venturi-scrubber means and being constructed and arranged to produce substantially constant pressure on its inlet side for a wide range of gas flow rates, said hood means, said first and second venturi-scrubber means and said exhaust means defining a gas flow path, gas composition sensing means coupled to said gas flow path, said sensing means being operable to produce signals which are functionally related to combustibility of said gases, skirt positioning means operatively coupled to said skirt means for adjusting the gap between the skirt means and the vessel opening, said skirt positioning means being operative for initially positioning said skirt above the opening in said vessel to draw air into said hood for oxidation of combustible gases and for lowering said hood to reduce the inflow of air to said hood when said gas composition sensing means indicates that stoichiometric conditions have been reached in said gas flow path.

Claim 46

Independent Claim 317 words

A system for collecting off-gases from a pneumatic metallurgical converter vessel, said vessel having an opening through which the gases exit from the vessel, gas collection hood means situated over the opening of the vessel and including skirt means advanceable and retractable to permit varying the gap between the vessel opening and the hood means, means for tilting said vessel between a first position wherein said hood is disposed above said opening and a second position wherein said vessel is oriented with said opening displaced from alignment with said hood, first venturi-scrubber means having an inlet connected to said hood and an outlet, said first venturi-scrubber means including means for regulating gas flow therethrough. second venturi-scrubber means having an inlet connected to the outlet of said first venturi-scrubber and an outlet, said second scrubber means including means for regulating gas flow therethrough selectively whereby to permit regulation of the gas pressure in said hood means, exhaust means having an inlet connected to the outlet of said second venturi-scrubber means and being constructed and arranged to produce substantially constant pressure on its inlet side for a wide range of gas flow rates, said hood means, said first and second venturi-scrubber means and said exhaust means defining a gas flow path, gas composition sensing means coupled to said gas flow path, said sensing means being operable to produce signals which are functionally related to combustibility of said gases, skirt positioning means operatively coupled to said skirt means for adjusting the gap between the skirt means and the vessel opening, said skirt positioning means being operative for initially positioning said skirt above the opening in said vessel to draw air into said hood for oxidation of combustible gases and for lowering said hood to reduce the inflow of air to said hood when said gas composition sensing means indicates that stoichiometric conditions have been reached in said gas flow path.

Claim 47

Dependent Claim 18 words

The system set forth in claim 42 wherein said gas composition sensing means comprises partial pressure measuring means.

Claim 48

Dependent Claim 118 words

The system set forth in claim 43 and including an auxiliary hood means adjacent said gas collecting hood means and adapted to collect emission from the vessel when the latter it tilted to its second position, duct means connecting the alternate hood means to the inlet of said second gas cleaning means to the inlet of said second venturi scrubber means and valve means connected in said duct means, valve operator means for operating said valve means to connect said auxiliary hood means to said second venturi-scrubber means when said vessel is tilted to its second position and for closing said valve means to prevent the inflow of air therethrough when said vessel is in its first position.

Claim 49

Dependent Claim 52 words

The system set forth in claim 44 and including a source of a non-oxidizing gas, second valve means for coupling said source to said gas collecting hood means, said second valve means being operative to deliver said non-oxidizing gas to said hood means when said vessel is tilted to its second position.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1978-09-29	1979-03-31	1979-09-30	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1982-09-29	1983-03-31	1983-09-30	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1986-09-29	1987-03-31	1987-09-30	$7700.00	Window Closed / Lapsed

Method and apparatus for air pollution control combined with safe recovery and control of gases from a bottom-blown steel converter vessel

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