CA1134142A - Exothermic reaction process - Google Patents
Exothermic reaction processInfo
- Publication number
- CA1134142A CA1134142A CA357,972A CA357972A CA1134142A CA 1134142 A CA1134142 A CA 1134142A CA 357972 A CA357972 A CA 357972A CA 1134142 A CA1134142 A CA 1134142A
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- shielding
- reactant gas
- pressure
- flow rate
- manifold
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Abstract
ABSTRACT OF THE DISCLOSURE
An exothermic reaction process is des-cribed, in which a reactor is used which has a refractory lining and a plurality of annular nozzles mounted in said lining. Each of said nozzles have an inner reactant gas passage and an annular shielding gas passage surrounding said reactant gas passage. A reactant gas is supplied through a reactant gas manifold and a plurality of reactant gas feed conduits connecting said reactor gas manifold to respective ones of said reactant gas passages and is used for an exothermic reaction in said reactor. A shielding fluid is supplied through a shielding fluid manifold and a plurality of shielding fluid feed conduits connecting said shielding fluid manifold to res-pective ones of said shielding fluid passages. The pressure in said reactant gas manifold is sensed and the flow in each of said shielding fluid feed conduits is controlled in dependence on the conditions in said reactant gas manifold so as to prevent a pressure rise in each of said shielding fluid feed conduits above an upper limit, which depends on the pressure in said reactant gas mani-fold, and, as long as said pressure in said shielding gas feed conduit is below said upper limit, to maintain a predetermined ratio between the flow rate in each of said shielding gas feed conduits and the flow rate in said reactant gas manifold.
An exothermic reaction process is des-cribed, in which a reactor is used which has a refractory lining and a plurality of annular nozzles mounted in said lining. Each of said nozzles have an inner reactant gas passage and an annular shielding gas passage surrounding said reactant gas passage. A reactant gas is supplied through a reactant gas manifold and a plurality of reactant gas feed conduits connecting said reactor gas manifold to respective ones of said reactant gas passages and is used for an exothermic reaction in said reactor. A shielding fluid is supplied through a shielding fluid manifold and a plurality of shielding fluid feed conduits connecting said shielding fluid manifold to res-pective ones of said shielding fluid passages. The pressure in said reactant gas manifold is sensed and the flow in each of said shielding fluid feed conduits is controlled in dependence on the conditions in said reactant gas manifold so as to prevent a pressure rise in each of said shielding fluid feed conduits above an upper limit, which depends on the pressure in said reactant gas mani-fold, and, as long as said pressure in said shielding gas feed conduit is below said upper limit, to maintain a predetermined ratio between the flow rate in each of said shielding gas feed conduits and the flow rate in said reactant gas manifold.
Description
1~3~42 This invention relates to a process and system for a controlled supply of a shielding fluid to a plurality of annular nozzles, which are mounted in the refractory lining of a refining vessel. Each of said annular nozzles defines an inner passage for a refining gas and an annular shielding fluid passage surrounding said inner passase. The inner passages of said nozzles are connected by respective refining gas feed conduits to a refining gas manifold. The annular 0 passsges of said nozzles are connected by respective shielding fluid feed conduits to a shielding fluid manifold. The pressure in the shielding fluid feed conduits i8 controlled in dependence on the pressure in the refining gas manifold.
~ hen ferrous metal is refined by means of oxygen, ~hich i9 blown into the molten metal through nozzles mounted in the refractory lining of the re-fining vessel, an overheating of the outlet end of the nozzle and the surrounding refractory must be~ ~ -Zo prevented in that a shielding fluid i~ gaseous or -;
liquid form is injected at the same time. For this purpose~ annular nozzles are provided, ~hich extend through the refractory lining and define an inner refining gas passage and an annular shielding fluid passage surrounding the refininy gas passage. In such a nozzle, the refining gas emerging from the inner refining gas passage may undesirably enter the annular passage for the shielding fluid or the shielding fluid emerging from the annular passage may undesirably enter 30 the inner refining gas passage. A disturbing fire may be f ~
~i34142 ignited in such case if the refining gas consists of pure oxygen and the shielding fluid is combustible and consists e.g., of propane OI' oil. For this reason the ratios of the pressures and ~low rates of the refining gas and shielding fluid supplied to each nozzle should be so controlled that the nozzles will not be clogged by accretion and will not be wear at an excessively high rate.
It has already been proposed (German Patent 0 Specification 2,326,754) to control the supply of the shielding fluid to each annular nozzle in dependence on the supply of refining gas in that the flow in each of the branch conduits which connect the shielding fluid manifold to respective annular nozzles is controlled by a control valve, which is adjusted in dependence on the pressure in the refining gas manifold so that the pressure of the 6hielding fluid cannot undesirably rise above the refining gas pressure and, as a result, the shielding fluid cannot enter the re-zO fining gag passage of an annular nozzle. On the otherhand, an ingress of refining gas into the annular passage for the shielding fluid can only be prevented if the pressure in the shielding fluid manifold i6 50 high that the shielding fluid will be under a sufficiently high pressure in the shielding fluid passage when the control valve is opened. ~hereas such a pre~sure control arrangement can prevent a flow of refining gas and shielding fluid into the respective other pa~age, it will not ensure a uni~orm distribution 30 of the refinlng gaa and of the shielding Fluid to the
~ hen ferrous metal is refined by means of oxygen, ~hich i9 blown into the molten metal through nozzles mounted in the refractory lining of the re-fining vessel, an overheating of the outlet end of the nozzle and the surrounding refractory must be~ ~ -Zo prevented in that a shielding fluid i~ gaseous or -;
liquid form is injected at the same time. For this purpose~ annular nozzles are provided, ~hich extend through the refractory lining and define an inner refining gas passage and an annular shielding fluid passage surrounding the refininy gas passage. In such a nozzle, the refining gas emerging from the inner refining gas passage may undesirably enter the annular passage for the shielding fluid or the shielding fluid emerging from the annular passage may undesirably enter 30 the inner refining gas passage. A disturbing fire may be f ~
~i34142 ignited in such case if the refining gas consists of pure oxygen and the shielding fluid is combustible and consists e.g., of propane OI' oil. For this reason the ratios of the pressures and ~low rates of the refining gas and shielding fluid supplied to each nozzle should be so controlled that the nozzles will not be clogged by accretion and will not be wear at an excessively high rate.
It has already been proposed (German Patent 0 Specification 2,326,754) to control the supply of the shielding fluid to each annular nozzle in dependence on the supply of refining gas in that the flow in each of the branch conduits which connect the shielding fluid manifold to respective annular nozzles is controlled by a control valve, which is adjusted in dependence on the pressure in the refining gas manifold so that the pressure of the 6hielding fluid cannot undesirably rise above the refining gas pressure and, as a result, the shielding fluid cannot enter the re-zO fining gag passage of an annular nozzle. On the otherhand, an ingress of refining gas into the annular passage for the shielding fluid can only be prevented if the pressure in the shielding fluid manifold i6 50 high that the shielding fluid will be under a sufficiently high pressure in the shielding fluid passage when the control valve is opened. ~hereas such a pre~sure control arrangement can prevent a flow of refining gas and shielding fluid into the respective other pa~age, it will not ensure a uni~orm distribution 30 of the refinlng gaa and of the shielding Fluid to the
- 2 -~3414Z
annular nozzles. To ensure a low wear and a trouble- ~-free operation, the shielding fluid should ~e uni-formly distributed so that the desired ratio of the refining gas and shielding fluid flow rates can be ensured at all nozzles.
It i5 an ohject of the invention so to improve a process of the kind described first herein-before that a uniform distribution of the refining gas and of the shielding fluid to the several annular 10 nozzles can be ensured.
This ohject is acco~plished according to the invention in that the flow rate in each shielding fluid feed conduit is controlled in dependence on the flow rate in the refining gas manifold and~he pressure in each shielding fluid feed conduit is kept below an upper limit, which depends on the pressure in the re-fining gas manifold.
It i9 apparent, that the flow in each shielding fluid feed conduit rather than the pressure 20 is primarily controlled so that a desired ratio of the flow rates of refining gas and shielding fluid can be maintained For each annular nozzle and it is ensured that the shielding fluid will produce the optimum nhielding and cooling effects. But a mere flo~
rate control cannot prevent the pressure of the shielding fluid to rise to such a high value that the shielding fluid emerging from an annular nozzle can enter the refining gas passage of the same nozzle.
For this reason the ~low rate control is combined with 30 an overriding pressure control, whlch prevents the : `
~3~142 pressure in eaGh shielding fluid feed conduit Fram rising above an upper limit, which depends on the instantaneDus refining gas pre~sure. In the process according to the invention, the pressure control serves merely to keep the pressure in the shielding fluid feed conduits leading to respective annular nozzles at values which are safe in relation to the refining gas pressure so that the flow rate control can be fully effective when the shielding 10 gas pressure is below its highest permissible value.
The conditions which ensùre a uniform distribution ~ -of the refining gas and of the shielding fluid to the several annular nozzles can thus be maintained ~-with simple means.
The control of the flow rate of the shielding fluid supplied to each annular nozzle in combination with an overriding pressure control can be effected in various waysc For instance, the flow in each ~ -shielding fluid feed con~uit may be controlled by Zo two control valves, which are connected in series, and one o~ these control valves may be actuated by a suitable pressure controller and the other by a ~low rate controller. But in such an arrangement, an adjustment of one control valve will result in an ad~ustment of the other control valve because the pressure and the flow rate cannot be changed in-dependently of each other. For this reason it will be more desirable to control the flow in each shielding fluid ~eed conduit by a single control valve, which 30 i9 sd~u~table by a control device, which comprises a ~ _ ^~
~34'1~2 flow rate controller and a pressure controller. The flow rate controller has q reference input connected to a flow rate sensor for sensing the flow rate in the refining gas manifold and another input connected to a flow rate sensor for sensing the flow rate in the shielding 989 feed conduit. The pressure controller has a reference input connected to a pressure sensor for sensing the pressure in the refining gas manifold and another input connected to à pressure sensor for 0 sensing the pressure in the shielding fluid feed conduit. The pressure control controller and the Flow ~;~
rate control controller are connected to the actuator for the con~rol valve through a minimum-selecting ~-.. ..
compar~tor.
In such an arrangement it i9 ensured in a simple manner that the control valves far con~rolling the flow in the shielding fluid feed conduits leading to the respective annular nozzles are adjusted by the -~
pressùre controller w~e~ the pressure of the shielding Zo fluid exceeds the reference value and by the flow rate controller when the pressure of the shielding ;
fluid is below the reference value. The comparator i9 connected to the flow rate controller and to the pressure controller and ascertains which of the control 51gnal~ delivered by the9e controllers corresponds to a ~maller flow area of the control valve, and the comparator passes only that control signal to the actuator for the control valve 90 that the latter is correspondingly adjuste~. The oth~r control signal, which corresponds to a larger flow area, is blocked ~L~3~1~2 by the comparator~ When the shielding gas pressure is less than the highest permissible pressure, the supply of the shielding fluid to each annular nozzle will be controlled by the associated flo~
rate controller. On the other hand, the control valve will be controlled by the pressure controller as soon as the pressure of the shielding gas reaches the reference value indicating the highest permissible pressure. The comparator connected to both controllers ~ -10 of the control system thus selects the control signal correspon~ing to the smaller flow area. ~- ;
aecause the flow rate of the refining gas in the refining gas manifold is proportional to the flow rate of the refining gas in each of the re-fining gas feed conduits leading to the respective nozzles, as the resistance to the flow of the refining gas adjacent to the annular nozzle varies hardly~and differ5 in this respect from the resistance to the ~low of the shielding fluid, the flow rate in the Z shielding fluid feed conduits leading to the several annular nozzles i9 controlled in dependence on the flow rate of the refining gas in the refining gas manifold~ A desired ratio of the flow rates in the re~ining gas and shielding fluid feed conduits can be maintained in a simple manner in that the flow rate sensor in the refining gas manifold is connected to the flow rate controller by a preFerably adjust~
able scaling circuit. ~y means of that scaling circuit, the signal representing the flow rate in the reflniny ga~ manifold can be proportionally re-~ ~134142 duced to represent theflo~ rate in each of the refining gas feed conduits leading to respective annular nozzles. The ratio of the flow rate in the refining gas manifold and in each refining gas feed conduit may change, e.g., when a nozzle has failed and this change can be taken into account by an adjustment of the scaling circuit.
Similar means may be used to convert the signal representing the pressure in the refining 10 gas manifold to a signal representing the pressure ~ -~
in each refining gas feed conduit. To this end, the pressure sensor in the refining gas manifold i8 connected to the pres9ure controller by a preferably adjustable scaling circuit.
A system according to the invention is shown by way of example on the drawingg, in which ;;
Figure 1 is a simplified olock circuit diagram showing a gystem according to the invention ^
for a controlled supply of 8 shielding fluid to a -`~
Z plurality of annular nozzles mounted in the re- ~;
fractory lining of a refining vessel and Figure 2 is a block circuit diagram showing the basic arrangement of the control system for one o~ the annular nozzles~
Annular nozzles Z are mounted in the refractory lining 1 of a refining vessel and consist each of t~o concentric tubes, which define an inner refining gas passage 3 and an annular shielding fluid passage ~, which surrounds the refining gas
annular nozzles. To ensure a low wear and a trouble- ~-free operation, the shielding fluid should ~e uni-formly distributed so that the desired ratio of the refining gas and shielding fluid flow rates can be ensured at all nozzles.
It i5 an ohject of the invention so to improve a process of the kind described first herein-before that a uniform distribution of the refining gas and of the shielding fluid to the several annular 10 nozzles can be ensured.
This ohject is acco~plished according to the invention in that the flow rate in each shielding fluid feed conduit is controlled in dependence on the flow rate in the refining gas manifold and~he pressure in each shielding fluid feed conduit is kept below an upper limit, which depends on the pressure in the re-fining gas manifold.
It i9 apparent, that the flow in each shielding fluid feed conduit rather than the pressure 20 is primarily controlled so that a desired ratio of the flow rates of refining gas and shielding fluid can be maintained For each annular nozzle and it is ensured that the shielding fluid will produce the optimum nhielding and cooling effects. But a mere flo~
rate control cannot prevent the pressure of the shielding fluid to rise to such a high value that the shielding fluid emerging from an annular nozzle can enter the refining gas passage of the same nozzle.
For this reason the ~low rate control is combined with 30 an overriding pressure control, whlch prevents the : `
~3~142 pressure in eaGh shielding fluid feed conduit Fram rising above an upper limit, which depends on the instantaneDus refining gas pre~sure. In the process according to the invention, the pressure control serves merely to keep the pressure in the shielding fluid feed conduits leading to respective annular nozzles at values which are safe in relation to the refining gas pressure so that the flow rate control can be fully effective when the shielding 10 gas pressure is below its highest permissible value.
The conditions which ensùre a uniform distribution ~ -of the refining gas and of the shielding fluid to the several annular nozzles can thus be maintained ~-with simple means.
The control of the flow rate of the shielding fluid supplied to each annular nozzle in combination with an overriding pressure control can be effected in various waysc For instance, the flow in each ~ -shielding fluid feed con~uit may be controlled by Zo two control valves, which are connected in series, and one o~ these control valves may be actuated by a suitable pressure controller and the other by a ~low rate controller. But in such an arrangement, an adjustment of one control valve will result in an ad~ustment of the other control valve because the pressure and the flow rate cannot be changed in-dependently of each other. For this reason it will be more desirable to control the flow in each shielding fluid ~eed conduit by a single control valve, which 30 i9 sd~u~table by a control device, which comprises a ~ _ ^~
~34'1~2 flow rate controller and a pressure controller. The flow rate controller has q reference input connected to a flow rate sensor for sensing the flow rate in the refining gas manifold and another input connected to a flow rate sensor for sensing the flow rate in the shielding 989 feed conduit. The pressure controller has a reference input connected to a pressure sensor for sensing the pressure in the refining gas manifold and another input connected to à pressure sensor for 0 sensing the pressure in the shielding fluid feed conduit. The pressure control controller and the Flow ~;~
rate control controller are connected to the actuator for the con~rol valve through a minimum-selecting ~-.. ..
compar~tor.
In such an arrangement it i9 ensured in a simple manner that the control valves far con~rolling the flow in the shielding fluid feed conduits leading to the respective annular nozzles are adjusted by the -~
pressùre controller w~e~ the pressure of the shielding Zo fluid exceeds the reference value and by the flow rate controller when the pressure of the shielding ;
fluid is below the reference value. The comparator i9 connected to the flow rate controller and to the pressure controller and ascertains which of the control 51gnal~ delivered by the9e controllers corresponds to a ~maller flow area of the control valve, and the comparator passes only that control signal to the actuator for the control valve 90 that the latter is correspondingly adjuste~. The oth~r control signal, which corresponds to a larger flow area, is blocked ~L~3~1~2 by the comparator~ When the shielding gas pressure is less than the highest permissible pressure, the supply of the shielding fluid to each annular nozzle will be controlled by the associated flo~
rate controller. On the other hand, the control valve will be controlled by the pressure controller as soon as the pressure of the shielding gas reaches the reference value indicating the highest permissible pressure. The comparator connected to both controllers ~ -10 of the control system thus selects the control signal correspon~ing to the smaller flow area. ~- ;
aecause the flow rate of the refining gas in the refining gas manifold is proportional to the flow rate of the refining gas in each of the re-fining gas feed conduits leading to the respective nozzles, as the resistance to the flow of the refining gas adjacent to the annular nozzle varies hardly~and differ5 in this respect from the resistance to the ~low of the shielding fluid, the flow rate in the Z shielding fluid feed conduits leading to the several annular nozzles i9 controlled in dependence on the flow rate of the refining gas in the refining gas manifold~ A desired ratio of the flow rates in the re~ining gas and shielding fluid feed conduits can be maintained in a simple manner in that the flow rate sensor in the refining gas manifold is connected to the flow rate controller by a preFerably adjust~
able scaling circuit. ~y means of that scaling circuit, the signal representing the flow rate in the reflniny ga~ manifold can be proportionally re-~ ~134142 duced to represent theflo~ rate in each of the refining gas feed conduits leading to respective annular nozzles. The ratio of the flow rate in the refining gas manifold and in each refining gas feed conduit may change, e.g., when a nozzle has failed and this change can be taken into account by an adjustment of the scaling circuit.
Similar means may be used to convert the signal representing the pressure in the refining 10 gas manifold to a signal representing the pressure ~ -~
in each refining gas feed conduit. To this end, the pressure sensor in the refining gas manifold i8 connected to the pres9ure controller by a preferably adjustable scaling circuit.
A system according to the invention is shown by way of example on the drawingg, in which ;;
Figure 1 is a simplified olock circuit diagram showing a gystem according to the invention ^
for a controlled supply of 8 shielding fluid to a -`~
Z plurality of annular nozzles mounted in the re- ~;
fractory lining of a refining vessel and Figure 2 is a block circuit diagram showing the basic arrangement of the control system for one o~ the annular nozzles~
Annular nozzles Z are mounted in the refractory lining 1 of a refining vessel and consist each of t~o concentric tubes, which define an inner refining gas passage 3 and an annular shielding fluid passage ~, which surrounds the refining gas
3 passage 3. A refining gas consisting, e.g., of oxygen ' . . . . ' ' . ~ ' .
- . . .
is supplied to the refining gas passage 3 of each annular nozzle Z by one of several feed conduits 6, which are connected to a refining gas manifold 5.
A shie~ding fluid is supplied to the annular passage
- . . .
is supplied to the refining gas passage 3 of each annular nozzle Z by one of several feed conduits 6, which are connected to a refining gas manifold 5.
A shie~ding fluid is supplied to the annular passage
4 of each annular nozzle 2 by Dne of several feeo conduits 8, which are connected to a shielding fluid manifold 7. To ensure a unifDrm distribution of the shielding fluidt~o all annular nozzles 2 in dependence on the refining gas pressure, the flow rate and 10 pressure of the shielding fluid supplied to each annular nozzle Z are controlled by a control valve 9 connected between the shielding fluid mani~old 7 and the respective feed conduit 8. For this purpose, ~ :
each control valve 9 is actuated by a separate control device 10, which receives a flow rate reference sig- ;
nal from a flow rate sensor 11 for sensing the flo~
rate in the refining gas manifold 5 and a pressure reference signal fro~ a pressure sensor 12 for sensing the pressure in the refining gas ~anifold 5. :
In the control device 10, these reference signals are compared with signals representing the actual flow rate and the actual pressure in the associated ehielding gas feed cond4it 8 and delivered by a flow rate eeneor 13 and a pressure sensor 14, which are arranged in the as~ociated feed conduit 8. The control devlce 10 comprises means for deciding whether the a~sociated control valve 9 is to be controlled in dependence on the flow rate or the pressure in the associated shielding fluid feed conduit 8. A control in dependence on pressure will not be effected unless - 8 _ .
1~L3414Z
the pressure detected hy the pressure sensor 1~
has risen to a value which has a certain ratio to the refining gas pressure sensed by the pressure sensor 12 in the manifold 5 and a further pressure rise in the feed conduit 8 might cause shielding fluid from the annular passage 4 to enter the re-fining gas passage 3. The pressure sensor 1Z
determines an upper limit for the pressure in the shieldin9 fluid feed conduits 8. As soon as the 10 pressure in a given feed conduit 8 exceeds that upper limit, the control device 10 will cause the respective control valve 9 to be actuated in a closing sense. When the pressure in a given shielding fluid feed conduit B is below the upper limit, the flow rate control will be fully effective and each control valve 9 will then be controlled to maintain a predetermined ratio between the flow rates of refining gas and shielding fluid discharged by each annular nozzle 2. This will ensure that the wear of the annular nozzles 2 and of the surrounding re~ractory 1 will be slight and uniform.
The refining gas floLJ rate may be controlled by a suitable controller 15, which actuates a control valve 16 incorporal;ed in the refining gas manifold anrl tn wi-lich a rlow rate signal is delivered by a flow rate sensor 11. Similarly, the rlow rate oF the 6hielding fluid in the manifold 7 can be additionally controlled so th~t the operation of the plant can oe continued even when the control devices 10 have ~o Failed~ [n sucil case7 the control valves 9 associaled -- '3 --,~
~34142 with the feed conduits ~ must be adju~ted by hano.
For a simple combination of a flow rate control and an overriding pressure cantrol t the Control device 10 shown in Figure Z comprises a flow rate controller 17 and a pressure controller 1~
The flow rate controller 17 is supplied at a reference input with the output signals of the flow rate sensor 11 and at another input with the output signal of the flow rate sensor 13. The pressure controller 18 is supplied at a referenGe input with the output signal of the pressure sensor 12 and at another in-put with the output signal of the pressure sensor 14.
~ecause during undisturbed operation the flow rate and pressure adjacent to the annular nozzles Z ~re in a predetermined relation to the rate and pre~sure ;
in the respective manifold, the reference signals supplied to the flow rate controller and pressure controller, respectively, must be scaled down cDrrespondingly. For this purpose, a scaling circuit 19 is connected between the flow rate sensor 11 and the flow rate controller 17 and a scaling circuit 20 is connected between the pressure sensor 12 and the presr~ure contro~er 1B.
The control signals delivered by the controllers 17 and 1~ are applied to a minimum-selecting comparator circuit 21, which transmits to the actuator 22 for the control valve only that ~ntrol signal which corresponds to a smaller flow area nf the control valve 9 than the other control ign.llO The control signal which corresponds to a ~34142 laryer flow area is blocked by the comparatorcircuit 21. In this way, the desired combined flow rate and pregsure control is e~fected. When the pressure which i9 represented by the signal that is delivered by the pressure sensor 1Z via the scaling circuit ZO to the presgure controller 1 exceeds the pressure sensed by the pressure sensor 14~ the pressure controller 18 tends to actuate the control valve 9 in an opening sense so that the 10 flow rate control by the flow rate controller 17 can be fully effective until the flow rate control tends to open the control valve 9 to such an extent that the pressure in the feed conduit ~ exceeds the reference pressure. In that case, as has been explained hereinbefore, the control valve 9 will not be opened further because the comparator circuit 21 then blocks the control signal delivered by the flow ratè controller 17 and transmits only the control signal delivered oy the pressure controlIer.
zO aecause the pressure af the refining gas may exhibit ~;`
large ~luctuations~ a reference signal depending on the actual refining gas pressure must be applied to the pressure contro~er. -, . . .
,
each control valve 9 is actuated by a separate control device 10, which receives a flow rate reference sig- ;
nal from a flow rate sensor 11 for sensing the flo~
rate in the refining gas manifold 5 and a pressure reference signal fro~ a pressure sensor 12 for sensing the pressure in the refining gas ~anifold 5. :
In the control device 10, these reference signals are compared with signals representing the actual flow rate and the actual pressure in the associated ehielding gas feed cond4it 8 and delivered by a flow rate eeneor 13 and a pressure sensor 14, which are arranged in the as~ociated feed conduit 8. The control devlce 10 comprises means for deciding whether the a~sociated control valve 9 is to be controlled in dependence on the flow rate or the pressure in the associated shielding fluid feed conduit 8. A control in dependence on pressure will not be effected unless - 8 _ .
1~L3414Z
the pressure detected hy the pressure sensor 1~
has risen to a value which has a certain ratio to the refining gas pressure sensed by the pressure sensor 12 in the manifold 5 and a further pressure rise in the feed conduit 8 might cause shielding fluid from the annular passage 4 to enter the re-fining gas passage 3. The pressure sensor 1Z
determines an upper limit for the pressure in the shieldin9 fluid feed conduits 8. As soon as the 10 pressure in a given feed conduit 8 exceeds that upper limit, the control device 10 will cause the respective control valve 9 to be actuated in a closing sense. When the pressure in a given shielding fluid feed conduit B is below the upper limit, the flow rate control will be fully effective and each control valve 9 will then be controlled to maintain a predetermined ratio between the flow rates of refining gas and shielding fluid discharged by each annular nozzle 2. This will ensure that the wear of the annular nozzles 2 and of the surrounding re~ractory 1 will be slight and uniform.
The refining gas floLJ rate may be controlled by a suitable controller 15, which actuates a control valve 16 incorporal;ed in the refining gas manifold anrl tn wi-lich a rlow rate signal is delivered by a flow rate sensor 11. Similarly, the rlow rate oF the 6hielding fluid in the manifold 7 can be additionally controlled so th~t the operation of the plant can oe continued even when the control devices 10 have ~o Failed~ [n sucil case7 the control valves 9 associaled -- '3 --,~
~34142 with the feed conduits ~ must be adju~ted by hano.
For a simple combination of a flow rate control and an overriding pressure cantrol t the Control device 10 shown in Figure Z comprises a flow rate controller 17 and a pressure controller 1~
The flow rate controller 17 is supplied at a reference input with the output signals of the flow rate sensor 11 and at another input with the output signal of the flow rate sensor 13. The pressure controller 18 is supplied at a referenGe input with the output signal of the pressure sensor 12 and at another in-put with the output signal of the pressure sensor 14.
~ecause during undisturbed operation the flow rate and pressure adjacent to the annular nozzles Z ~re in a predetermined relation to the rate and pre~sure ;
in the respective manifold, the reference signals supplied to the flow rate controller and pressure controller, respectively, must be scaled down cDrrespondingly. For this purpose, a scaling circuit 19 is connected between the flow rate sensor 11 and the flow rate controller 17 and a scaling circuit 20 is connected between the pressure sensor 12 and the presr~ure contro~er 1B.
The control signals delivered by the controllers 17 and 1~ are applied to a minimum-selecting comparator circuit 21, which transmits to the actuator 22 for the control valve only that ~ntrol signal which corresponds to a smaller flow area nf the control valve 9 than the other control ign.llO The control signal which corresponds to a ~34142 laryer flow area is blocked by the comparatorcircuit 21. In this way, the desired combined flow rate and pregsure control is e~fected. When the pressure which i9 represented by the signal that is delivered by the pressure sensor 1Z via the scaling circuit ZO to the presgure controller 1 exceeds the pressure sensed by the pressure sensor 14~ the pressure controller 18 tends to actuate the control valve 9 in an opening sense so that the 10 flow rate control by the flow rate controller 17 can be fully effective until the flow rate control tends to open the control valve 9 to such an extent that the pressure in the feed conduit ~ exceeds the reference pressure. In that case, as has been explained hereinbefore, the control valve 9 will not be opened further because the comparator circuit 21 then blocks the control signal delivered by the flow ratè controller 17 and transmits only the control signal delivered oy the pressure controlIer.
zO aecause the pressure af the refining gas may exhibit ~;`
large ~luctuations~ a reference signal depending on the actual refining gas pressure must be applied to the pressure contro~er. -, . . .
,
Claims (10)
1. In an exothermic reaction process using a reactor having a refractory lining and a plurality of annular nozzles mounted in said lining, each of said nozzles having an inner reactant gas passage and an annular shielding fluid passage surrounding said reactant gas passage, which process comprises supplying a reactant gas through a reactant gas manifold and a plurality of reactant gas feed conduits connecting said reactant gas manifold to respective ones of said reactant gas passages, using said reactant gas for an exothermic reaction in said reactor, supplying a shielding fluid through a shielding fluid manifold and a plurality of shielding fluid feed conduits connecting said shielding fluid manifold to respective ones of said shielding fluid passages, sensing the pressure in said reactant gas manifold, and controlling the flow in each of said shielding fluid feed conduits in dependence on the conditions in said reactant gas manifold, the improvement resi-ding in that the flow in each of said shielding gas feed conduits is controlled to prevent a pressure rise therein above an upper limit, which depends on the pressure in said reactant gas manifold, and, as long as said pressure in said shielding gas feed conduit is below said upper limit, to maintain a predetermined ratio between the flow rate in said shielding gas feed conduit and the flow rate in said reactant gas manifold.
2. The improvement set forth in claim 1, wherein said reactant gas comprises oxygen and is used for an oxidizing reaction in said reactor.
3. The improvement set forth in claim 1, wherein said reactant gas consists of a refining gas and is used to refine molten ferrous metal in said reactor.
4. A system for supplying a reactant gas and a shielding fluid to a reactor having a refractory lining and a plurality of annular nozzles mounted in said lining, each of said nozzles having an inner reactant gas passage and an annular shielding fluid passage surrounding said reactant gas passage, which system comprises a reactant gas manifold and a plurality of reactant gas feed conduits connected to said reactant gas manifold and adapted to be connected to respective ones of said reactant gas passages, a shielding fluid manifold and a plurality of shielding fluid feed conduits connected to said shielding fluid manifold and adapted to be connected to respective ones of said shielding fluid passages, a reactant gas pressure sensor for sensing the pressure in said reactant gas manifold, and a control system for controlling the flow in said shielding flow feed conduits in dependence on the conditions in said reactant gas manifold, the improvement residing in that said control system comprises pressure control means adapted to prevent a pressure rise in each of said shielding gas feed conduits above an upper limit, which depends on the pressure in said reactant gas manifold, and flow rate control means for maintaining a predetermined ratio between the flow rate in said shielding gas feed conduit and the flow rate in said reactant gas manifold as long as said pressure in said shielding gas feed conduit is below said upper limit.
5. A system as set forth in claim 4, wherein said pressure control means comprise, for each of said shielding gas feed conduits, a pressure sensor for sensing the pressure in the associated shielding gas feed conduit and a pressure controller, which has a reference input operatively connected to said reactant gas pressure sensor and a second input connected to the shielding gas pressure sensor for the same shielding gas feed conduit, said pressure controller being adapted to generate a pressure control signal in dependence on said pressure in said reactant gas manifold and the pressure in the associated shielding gas feed conduit, said flow rate control means comprise a reactant gas flow rate sensor for sensing the flow rate in said reactant gas manifold, and, for each of said shielding gas feed conduits, a shielding gas flow rate sensor for sensing the flow rate in the associated shielding gas feed conduit, and a flow rate controller, which has a reference input operatively connected to said reactant gas flow rate sensor and a second input operatively connected to said shielding gas flow rate sensor for the same shielding gas feed conduit, each of said flow rate controllers being adapted to generate a flow rate control signal in dependence on said flow rate in said reactant gas manifold and on said flow rate in the associated shielding gas feed conduits, and said control system comprises, for each of said shielding gas feed conduits, a control valve for controlling the flow in the associated shielding gas feed conduit, an actuator adapted to receive an actuator control signal and to control the flow area of the control valve for the same shielding gas feed con-duit in a predetermined relation to the magnitude of said actuator control signal, a comparator adapted to receive said pressure control signal and said flow rate control signal from the pressure and flow rate controllers for the same shielding gas feed conduit and to deliver to the actuator for the same shielding gas feed conduit as an actuator control signal only that of said flow rate and pressure control sig-nals which corresponds to a smaller flow area of the associated control valve.
6. The improvement set forth in claim 5, wherein the reference input of each of said flow rate controllers is connected to said reactant gas flow rate sensor by a scaling device.
7. The improvement set forth in claim 6, wherein said scaling device is adjustable.
8. The improvement set forth in claim 5, wherein the reference input of each of said pressure controllers is connected to said reactant gas pressure sensor by a scaling device.
9. The improvement set forth in claim 8, wherein said scaling device is adjustable.
10. A control signal generating circuit for use in a system for supplying a reactant gas and a shielding fluid to a reactor having a refractory lining and a plurality of annular nozzles mounted in said lining each of said nozzles having an inner reactant gas passage and an annular shielding fluid passage surrounding said reactant gas passage, which system comprises a reactant gas mainfold and a plurality of reactant gas feed conduits connected to said reactant gas manifold and adapted to be connected to respective ones of said reactant gas passages, a shielding fluid manifold and a plurality of shielding fluid feed conduits connected to said shielding fluid manifold and adapted to be connected to respective ones of said shielding fluid passages, a reactant gas pressure sensor for sensing the pressure in said reactant gas manifold, and a control system for controlling the flow in said shielding flow feed conduits in dependence on the conditions in said reactant gas manifold, said control system comprising for each of said shielding gas feed conduits a control valve for controlling the flow in the associated shielding gas feed conduit and an actuator adapted to receive an actuator control signal and to control the flow area of the control valve for the same shielding gas feed conduit in a predetermined relation to the magnitude of said control signal, said control signal generating circuit comprising for each of said shielding gas feed conduit a pressure sensor for sensing the pressure in the associated shielding gas feed conduit and a pressure controller, which has a reference input operatively connected to said reactant gas pressure sensor and a second input connected to the shielding gas pressure sensor for the same shielding gas feed conduit, said pressure controller being adapted to generate a pressure control signal in dependence on said pressure in said reactant gas mainfold and the pressure in the associated shielding gas feed conduit, said control signal generating circuit further comprising a reactant gas flow rate sensor for sensing the flow rate in said reactant gas manifold, and, for each of said shielding gas feed conduits, a shielding gas flow rate sensor for sensing the flow rate in the associated shielding gas feed conduit, and a flow rate con-troller, which has a reference input operatively connected to said reactant gas flow rate sensor and a second input operatively connected to said shielding gas flow rate sensor for the same shielding gas feed conduit, each of said flow rate controllers being adapted to generate a flow rate control signal in dependence on said flow rate in said reactant gas manifold and on said flow rate in the associated shielding gas feed conduits, and said control signal generating sircuit comprising for each of said shielding gas feed conduits a comparator adapted to receive said pressure control signal and said flow rate control signal from the pressure and flow rate controllers for the same shielding gas feed conduit and to deliver to the actuator for the same shielding gas feed conduit as an actuator control signal only that of said flow rate and pressure control signals which corresponds to a smaller flow area of the associated control valve.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA357,972A CA1134142A (en) | 1980-08-11 | 1980-08-11 | Exothermic reaction process |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA357,972A CA1134142A (en) | 1980-08-11 | 1980-08-11 | Exothermic reaction process |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1134142A true CA1134142A (en) | 1982-10-26 |
Family
ID=4117621
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA357,972A Expired CA1134142A (en) | 1980-08-11 | 1980-08-11 | Exothermic reaction process |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1134142A (en) |
-
1980
- 1980-08-11 CA CA357,972A patent/CA1134142A/en not_active Expired
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