CA1121743A - Gas/particle separating device - Google Patents
Gas/particle separating deviceInfo
- Publication number
- CA1121743A CA1121743A CA000275997A CA275997A CA1121743A CA 1121743 A CA1121743 A CA 1121743A CA 000275997 A CA000275997 A CA 000275997A CA 275997 A CA275997 A CA 275997A CA 1121743 A CA1121743 A CA 1121743A
- Authority
- CA
- Canada
- Prior art keywords
- cyclone separator
- vessel
- solid particles
- cylindrical
- inches
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
- B04C—APPARATUS USING FREE VORTEX FLOW, e.g. CYCLONES
- B04C5/00—Apparatus in which the axial direction of the vortex is reversed
- B04C5/24—Multiple arrangement thereof
- B04C5/28—Multiple arrangement thereof for parallel flow
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- Cyclones (AREA)
- Devices And Processes Conducted In The Presence Of Fluids And Solid Particles (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The invention provides a gas/particle separating system using a battery of cylindrical cyclone separator vessels in parallel, and fed from a common inlet for the mixture and connected to a common gas outlet. The solid particles are discharged from the bottom of each cylindrical vessel by suitable means such as a discharge valve.
The diameter of each separator is from 20 inches to 40,inches preferably 30 inches.
The invention provides a gas/particle separating system using a battery of cylindrical cyclone separator vessels in parallel, and fed from a common inlet for the mixture and connected to a common gas outlet. The solid particles are discharged from the bottom of each cylindrical vessel by suitable means such as a discharge valve.
The diameter of each separator is from 20 inches to 40,inches preferably 30 inches.
Description
Th~ present invention relates to an apparatus for and a method of separating particles from a gas stream, and is particularly useful in the field o~ recovering energy from the discharge gas flow from a fluid catalytic cracking unit regenerator vessel.
In the past it has been known to recover energy from the discharge flow from a catalytic cracking unit regeneratorvessel by passing the discharge gases through a waste heat boiler using the recovered heat to boil water to generate a steam flow which can then pass through a power recovery turbine. However, the efficiencies of the waste heat boiler and of the turbine used in the ste~m system leads to a very poor recovery rate of th~ total available energy in the outlet stream from the catalytic cracking unit regenerator.
In accordance with one aspect of the present invention we provide apparatus for separating solid particles from a gas stream comprising a plurality of cyclone separator ve~sels connected in parallel to be fed from a common gas source and to discharge to a common gas outlet, each of the cyclone separator vessels having a cylindrical separator chamber of substantially uniform internal diameter along its length of from 20 inches to 40 inches~ and being provided with means for discharging the separated solid particles from the bottom of the said cylindrical separator chamber. Such a sepaxating apparatu~ i~ capable of a very high separation efficiency coupled with a low rate of erosion by the solid 7~3 particles which enter the separator vessel by way of the inlet stream, and hence can be used to separate all or substantially all erosive solid particles from the discharge stream of a catalytic cra~king unit regenerator thereby allowing the discharge flow to enter directly into a power recovery turbine. Thu~s the recovery of energy from the fluid catalytic cracking unit regenerator discharge flow can be carried out more efficiently than hitherto by separating ou~ the solid particles from the discharge flow from the regenerator vessel, using the separating apparatus of the present invention and then passing the separated gases directly into a power recovery turbine.
The ~hoice of the particular diameter range in accordance with the present invention enables an extremely efficient separating action to be achieved with nevertheless a very low degree of erosion of the separator vessel walls so that the customary refractory or ceramic lining in the separator chamber can be avoided. For optimum results the inlet velocity to the individual separator vessels will be carefully related to the vessel diameter to give best separating efficiency with minimum erosion of the walls of the separating vessels. Although the range of diameters available in the cylindrical cyclone separator chambers of the present invention extends from 20" to 40", preferably 24" to 36", we find that a diameter of 30" gives optimum results.
f'~3 Where the assembly of cylindrical cyclone separators is to supply the power recovery turbine in a fluid catalytic cracking unit~ the avoidance of refractories or ceramics in the separator vessels is particularly advantageous since this eliminates the possibility of parts of the separator lining breaking away and constituting a safety hazard to the blades of the power recovery turbine.
In a preferred form of the present invention, therefore, each of the cylindrical cyclone separator chambers is formed of austenitic steel ~ithout any inner anti-erosion lining.
The low erosion rate in the separatin~ apparatus of the present invention results both from the fact that the separator vessels are cylindrical, rather than conical or part-conical, and from the fact that the diameter of the separator vessel proper is in the range of from 24 inches to 30 inches. ~f course a conical or part-conical solids ^ collecting hopper may be provided at one end of the cylindrical separator vessel but there will be no appreciable vortical gas flow at that part of the device so no erosion w~ll be expected.
Advantageously all of the cyclone separator vessels are fed from a common inlet manifold and they discharge to a common outlet duct by means of one or more discharge manifolds.
- ' ' ,: . : ': ' 7'~3 More advantayeously, each cyclone separator vessel has a respective solids-collecting hopper which discharges to a solids collector vessel for centralised removal of the recovered solidsO
Desirably the individual cyclone separator chambers are each pressurised to the same pressure as the exhaust duct from a catalytic cracking unit regenerator, and the system pressure is maintained along the solids discharge pipe from each cyclone separator vessel~
Alternatively, if desired, the various cyclone separator vessels can be incorporated in a main pressure vessel~ This has the advantage of simplified pressuri-sation of the separating apparatus but can often provide difficulties of maintenance or replacement of individual cyclone separators, when necessaryO
Conveniently each cylindrical cyclone separator has its respective solids-collecting hopper attached at its lower end and the main cyclone separator vessel opens into the solids-collecting hopper at a location ~0 spaced bel.ow the top of the solids hopper so as to a:Llow the swirling solid particles to be flung radially outwardly from the gas vortex in the separator, thereby to separate from the gas stream which can then escape vertica.lly upwardly along the core of the vortex towards the gas discharge duct at the top of the cylindrical cyclone separator vesselO
~ .
7~3 According to the present invention we also propose a method of ope.rating a fluid catalytic cracke~ unit comprising: discharging the product gas and entrained particulate solids from secondary cyclone separators within the regenerator chamber and conveying the stream to a gas/particle sepa:rating assembly comprising a plurality of individual cylindrical cyclone : separator vessels in parallel, each cyclone separator vessel having an internal diameter in the range from 20 inches to 40 inches, and the number of separators being chosen to suit the exhaust gas flow rate from the catalyst regenerator; recovering the particles of catalyst from the solid discharge section of each of the individual cylindrical cyclone separating vessels;
collecting the cleaned gas discharge flow from each separator of the assembly in a common discharge flow, .
passing this co~non discharge flow to an energy recovery turbine; and using the energy recovery turbine to drive .
an air compressor for supplying the inlet air to the regenerator chamber.
In order that the present invention may more readily be understood the following description is given by way of example, with reference to the accompanying drawings in which:-- ~:
~ , . . .
- Figure 1 is a side elevational view showing a cyclone separator cluster in accordance with the present nventlon;
Figure 2 is a top plan view of the cluster of S Figure 1, Figure 3A is a schematic view showing a prior art energy recovery system for a fluid catalytic cracking unit, and Figure 3B shows a possible more efficient arrangement using separating apparatus in accordance ~-with the present invention.
In Figures 1 and 2, there can be seen a cluster of individual cylindrical cyclone separator vessels 1 around a partially refractory-lined inlet manifold 2 in the form of the exhaust line ~rom a high pressure catalytic cracking unit regenerator. The individual cyclone separator vessels 1 have feed ducts 3 which introduce the particle-laden gas tangentially into the top of each separator to generate a vortex coaxially within the vessel 1.
From the top of each of the cylindrical separator vessels 1, the particles swirl round the axis of the chamber while descending towards a solids~collector hopper 4 at the foot of each cylindrical vessel 1, while the gases from the core of the vortex, now cleaned of substantially all the solids content, are discharged upwardly through exhaust duct 5 into the respectlve one of two exhaust ~ , ' ' ,"
-7'~3 manifolds 6a and 6_o sy the time the solids content has dropped into the solids-collecting hopper 4, separation will have been complete and the particles then build up in a pile in the bottom of the conical hopper section 7 before descending along the inclined dust-discharge pipe ~ into a central dust-collector vessel 9.
In accordance with the present invention, each of the cylindrical cyclone separator vessels has an inner diameter of from 20 inches to 40 inches and can consequently be matched to the desired gas throughput rate, so as to be subject to a sufficiently reduced degree of erosion (as compared with the erosion experienced in a conventional conical cyclone separator) that the walls of the cylindrical separator chamber of the vessel 1 and those of the solids-collecting hopper 4 at the foot of each vessel 1 can be formed of austenitic .cteel without the need for any refractory lining to improve the erosion-resistance properties of the chamberO The length o the cylindrical separator chamber will be designed appropriate to the degree of separation ef~iciency re~uiredO In the preferred embodiment of the apparatus the internal diameter of the cyclone separator vessels 1 is 30 inches~
Each of the separator chambers has an optimum throuyhput rate of solids-laden gas for separation, so as th~ total throughput of ~he separa~r unlt i9 required to ' ' :
.
be increased, for example in order to incorporate the separator assembly into a larger catalytic cracking plant, so the number of individual cylindrical separators of the form shown at 1 in Figure 1 has to be increased, if possible without departing from the preferred cyclone separator vessel diameter of 30 inches but definitely remainin~ within the range of values ~ from 20 inches to 40 inches.
A further feature of the present invention lies in the fact that each separator vessel together with its inlet ducting 3, its gas outlet ducting 5 and its dust outlet pipe 8 forms part of the pressurised system in the exhaust from the catalytic cracking unit regeneratorO
Thus rather than being encased within a pressure vessel, each of the separators together with its feed and discharge ducting constitutes a separate pressure vessel to which access can readily be obtained for maintenance and/
or removal when required. Equally, it is possible to incorporate adjustment means in the system connected to each individual cyclone separator vessel so that the system can be tuned for optimum separation efficiency of each individual cyclone separator vessel in the assembly.
Not only does the design of cyclone separator apparatus according to the present invention allow the use of austenitic steel without introduciny any erosion hazard, but also the austenitic material is sufficiently heat-_ g 7~3 resistant to accommodate a steady running temperature of1,450F in the inlet stream, with occasional transients up to 1800F. By choosing a cyclone separator vessel diameter in the range of 20 inches to Llo inches, it is possible to ensure that the individual cyclone separators will be free from blockage or build up of solidsO The feed rate of s`olids-laden gas through each inlet pipe 3 w.ill be carefully calculated to permit optimum separation levels to be achieved within the separator without overloading the separator to the extent that dust and other solid -particles build up in the disentrainment hopper 4 at a rate which is higher than can be accommodated by the solids discharge pipe 8.
With the austenitic steel walled cylindrical cyclone separator chambers 1 proposed in Figures 1 and 2, it is possible to maintain the internal pressure of approximately ~.0 atmospheres absolute, while nevertheless operating at the extremely high temperatures without any need for a refractory or other ceramic lining within the cylindrical cyclone separator chamber 1.
Another advantage of providing a cluster of individual cylindrical cyclone separator vessels forming separate pressure vessels of an .integrate~ assembly, lies ln the fact that a continuous pressurised feed of the _ 10 --' ~
7~3 separated solids component from the conical section 7 of the solids collecting hopper, along the solids discharge pipe and into the central solids collector vessel 9, can be established without the need for additional conveying means to transfer the collected solids to the central collector~ Furthermore, the discharge from the collector vessel 9 can be by way of pneumatic conveying using the gas pressure prevailing in the cyclone separator ehamber 1 as the conveying gas (in this case approximately 1% of the discharge gas flow entering the cyclone separator assembly will be used for conveying away the solids in the form of a pneumatically eonveyed stream).
Alternatively, a valve may be provided at the bottom of the solids collector vessel 9 and equipped with some form of air lock to preserve gas pressure within the colleetor vessel g while allowing intermittent discharge of the collected solids onto a mechanical conveyor for disposal.
For example the eollector vessel 9 may discharge through a first shut-off valve, into a disentrainment hopper whose outlet ineludes a second shut-off valve.
Figures 3A and 3B exempli.fy the advantages which can be derived using the cyclone separator assembly shown in Figures 1 and 2.
Figure 3A illustrates a conventional energy recovery system in a fluid catalytic cracker unit and shows r ,~
.'. ,. ~
~3 ~Z1743 that the regenerator vessel 10 includes both primary and secondary separators 11 and 12, respectively, of conventional form feeding a discharge pipe 13 leading to a waste heat boiler 14. The spent flue gas from the boiler 14 i~ discharged through flue 15 while water heated in the boiler is converted to steam in the line 16 to be fed to the inlet of a steam turbine 17. The shaft of the steam turbine 17 is linked to an air compressor 18 to supply air to the înlet feed to the regenerator vessel 10.
In the e~ample of Figure 3A, if the efficiency of the waste heat boiler is assumed to be 30%, and the efficiency of the combination of steam turbine 17 and compressor 18 (14%), then for every one hundred units of heat energy in the stream passing along pipe 13 from the regenerator chamber 10, thirty of these units are present in the steam line 16 and only four of these units of energy will be evident in the line from the air compressor 18.
Since the feed to the catalytic cracking regenerator chamber 10 requires twelve units o heat in the air supply~ eight of the units, i.e. 8% of the energy requirement, must be supplied from outside the system by external topping up.
A much more efficient way of recovering the energy in the line 13 can be appreciated from the alternative system illustrated in Figure 3 B where again the regenerator chamber 10 has primary and secondary 7'~3 cyclone separators 11 and 1~ of conical design, with the secondary conical cyclone separators 12 feeding a discharge line 13. This discharye line feeds a separating system 19 which is in fact the assembly or cluster of individual cyclone separating vessels 1 illustrated in Figures 1 and
In the past it has been known to recover energy from the discharge flow from a catalytic cracking unit regeneratorvessel by passing the discharge gases through a waste heat boiler using the recovered heat to boil water to generate a steam flow which can then pass through a power recovery turbine. However, the efficiencies of the waste heat boiler and of the turbine used in the ste~m system leads to a very poor recovery rate of th~ total available energy in the outlet stream from the catalytic cracking unit regenerator.
In accordance with one aspect of the present invention we provide apparatus for separating solid particles from a gas stream comprising a plurality of cyclone separator ve~sels connected in parallel to be fed from a common gas source and to discharge to a common gas outlet, each of the cyclone separator vessels having a cylindrical separator chamber of substantially uniform internal diameter along its length of from 20 inches to 40 inches~ and being provided with means for discharging the separated solid particles from the bottom of the said cylindrical separator chamber. Such a sepaxating apparatu~ i~ capable of a very high separation efficiency coupled with a low rate of erosion by the solid 7~3 particles which enter the separator vessel by way of the inlet stream, and hence can be used to separate all or substantially all erosive solid particles from the discharge stream of a catalytic cra~king unit regenerator thereby allowing the discharge flow to enter directly into a power recovery turbine. Thu~s the recovery of energy from the fluid catalytic cracking unit regenerator discharge flow can be carried out more efficiently than hitherto by separating ou~ the solid particles from the discharge flow from the regenerator vessel, using the separating apparatus of the present invention and then passing the separated gases directly into a power recovery turbine.
The ~hoice of the particular diameter range in accordance with the present invention enables an extremely efficient separating action to be achieved with nevertheless a very low degree of erosion of the separator vessel walls so that the customary refractory or ceramic lining in the separator chamber can be avoided. For optimum results the inlet velocity to the individual separator vessels will be carefully related to the vessel diameter to give best separating efficiency with minimum erosion of the walls of the separating vessels. Although the range of diameters available in the cylindrical cyclone separator chambers of the present invention extends from 20" to 40", preferably 24" to 36", we find that a diameter of 30" gives optimum results.
f'~3 Where the assembly of cylindrical cyclone separators is to supply the power recovery turbine in a fluid catalytic cracking unit~ the avoidance of refractories or ceramics in the separator vessels is particularly advantageous since this eliminates the possibility of parts of the separator lining breaking away and constituting a safety hazard to the blades of the power recovery turbine.
In a preferred form of the present invention, therefore, each of the cylindrical cyclone separator chambers is formed of austenitic steel ~ithout any inner anti-erosion lining.
The low erosion rate in the separatin~ apparatus of the present invention results both from the fact that the separator vessels are cylindrical, rather than conical or part-conical, and from the fact that the diameter of the separator vessel proper is in the range of from 24 inches to 30 inches. ~f course a conical or part-conical solids ^ collecting hopper may be provided at one end of the cylindrical separator vessel but there will be no appreciable vortical gas flow at that part of the device so no erosion w~ll be expected.
Advantageously all of the cyclone separator vessels are fed from a common inlet manifold and they discharge to a common outlet duct by means of one or more discharge manifolds.
- ' ' ,: . : ': ' 7'~3 More advantayeously, each cyclone separator vessel has a respective solids-collecting hopper which discharges to a solids collector vessel for centralised removal of the recovered solidsO
Desirably the individual cyclone separator chambers are each pressurised to the same pressure as the exhaust duct from a catalytic cracking unit regenerator, and the system pressure is maintained along the solids discharge pipe from each cyclone separator vessel~
Alternatively, if desired, the various cyclone separator vessels can be incorporated in a main pressure vessel~ This has the advantage of simplified pressuri-sation of the separating apparatus but can often provide difficulties of maintenance or replacement of individual cyclone separators, when necessaryO
Conveniently each cylindrical cyclone separator has its respective solids-collecting hopper attached at its lower end and the main cyclone separator vessel opens into the solids-collecting hopper at a location ~0 spaced bel.ow the top of the solids hopper so as to a:Llow the swirling solid particles to be flung radially outwardly from the gas vortex in the separator, thereby to separate from the gas stream which can then escape vertica.lly upwardly along the core of the vortex towards the gas discharge duct at the top of the cylindrical cyclone separator vesselO
~ .
7~3 According to the present invention we also propose a method of ope.rating a fluid catalytic cracke~ unit comprising: discharging the product gas and entrained particulate solids from secondary cyclone separators within the regenerator chamber and conveying the stream to a gas/particle sepa:rating assembly comprising a plurality of individual cylindrical cyclone : separator vessels in parallel, each cyclone separator vessel having an internal diameter in the range from 20 inches to 40 inches, and the number of separators being chosen to suit the exhaust gas flow rate from the catalyst regenerator; recovering the particles of catalyst from the solid discharge section of each of the individual cylindrical cyclone separating vessels;
collecting the cleaned gas discharge flow from each separator of the assembly in a common discharge flow, .
passing this co~non discharge flow to an energy recovery turbine; and using the energy recovery turbine to drive .
an air compressor for supplying the inlet air to the regenerator chamber.
In order that the present invention may more readily be understood the following description is given by way of example, with reference to the accompanying drawings in which:-- ~:
~ , . . .
- Figure 1 is a side elevational view showing a cyclone separator cluster in accordance with the present nventlon;
Figure 2 is a top plan view of the cluster of S Figure 1, Figure 3A is a schematic view showing a prior art energy recovery system for a fluid catalytic cracking unit, and Figure 3B shows a possible more efficient arrangement using separating apparatus in accordance ~-with the present invention.
In Figures 1 and 2, there can be seen a cluster of individual cylindrical cyclone separator vessels 1 around a partially refractory-lined inlet manifold 2 in the form of the exhaust line ~rom a high pressure catalytic cracking unit regenerator. The individual cyclone separator vessels 1 have feed ducts 3 which introduce the particle-laden gas tangentially into the top of each separator to generate a vortex coaxially within the vessel 1.
From the top of each of the cylindrical separator vessels 1, the particles swirl round the axis of the chamber while descending towards a solids~collector hopper 4 at the foot of each cylindrical vessel 1, while the gases from the core of the vortex, now cleaned of substantially all the solids content, are discharged upwardly through exhaust duct 5 into the respectlve one of two exhaust ~ , ' ' ,"
-7'~3 manifolds 6a and 6_o sy the time the solids content has dropped into the solids-collecting hopper 4, separation will have been complete and the particles then build up in a pile in the bottom of the conical hopper section 7 before descending along the inclined dust-discharge pipe ~ into a central dust-collector vessel 9.
In accordance with the present invention, each of the cylindrical cyclone separator vessels has an inner diameter of from 20 inches to 40 inches and can consequently be matched to the desired gas throughput rate, so as to be subject to a sufficiently reduced degree of erosion (as compared with the erosion experienced in a conventional conical cyclone separator) that the walls of the cylindrical separator chamber of the vessel 1 and those of the solids-collecting hopper 4 at the foot of each vessel 1 can be formed of austenitic .cteel without the need for any refractory lining to improve the erosion-resistance properties of the chamberO The length o the cylindrical separator chamber will be designed appropriate to the degree of separation ef~iciency re~uiredO In the preferred embodiment of the apparatus the internal diameter of the cyclone separator vessels 1 is 30 inches~
Each of the separator chambers has an optimum throuyhput rate of solids-laden gas for separation, so as th~ total throughput of ~he separa~r unlt i9 required to ' ' :
.
be increased, for example in order to incorporate the separator assembly into a larger catalytic cracking plant, so the number of individual cylindrical separators of the form shown at 1 in Figure 1 has to be increased, if possible without departing from the preferred cyclone separator vessel diameter of 30 inches but definitely remainin~ within the range of values ~ from 20 inches to 40 inches.
A further feature of the present invention lies in the fact that each separator vessel together with its inlet ducting 3, its gas outlet ducting 5 and its dust outlet pipe 8 forms part of the pressurised system in the exhaust from the catalytic cracking unit regeneratorO
Thus rather than being encased within a pressure vessel, each of the separators together with its feed and discharge ducting constitutes a separate pressure vessel to which access can readily be obtained for maintenance and/
or removal when required. Equally, it is possible to incorporate adjustment means in the system connected to each individual cyclone separator vessel so that the system can be tuned for optimum separation efficiency of each individual cyclone separator vessel in the assembly.
Not only does the design of cyclone separator apparatus according to the present invention allow the use of austenitic steel without introduciny any erosion hazard, but also the austenitic material is sufficiently heat-_ g 7~3 resistant to accommodate a steady running temperature of1,450F in the inlet stream, with occasional transients up to 1800F. By choosing a cyclone separator vessel diameter in the range of 20 inches to Llo inches, it is possible to ensure that the individual cyclone separators will be free from blockage or build up of solidsO The feed rate of s`olids-laden gas through each inlet pipe 3 w.ill be carefully calculated to permit optimum separation levels to be achieved within the separator without overloading the separator to the extent that dust and other solid -particles build up in the disentrainment hopper 4 at a rate which is higher than can be accommodated by the solids discharge pipe 8.
With the austenitic steel walled cylindrical cyclone separator chambers 1 proposed in Figures 1 and 2, it is possible to maintain the internal pressure of approximately ~.0 atmospheres absolute, while nevertheless operating at the extremely high temperatures without any need for a refractory or other ceramic lining within the cylindrical cyclone separator chamber 1.
Another advantage of providing a cluster of individual cylindrical cyclone separator vessels forming separate pressure vessels of an .integrate~ assembly, lies ln the fact that a continuous pressurised feed of the _ 10 --' ~
7~3 separated solids component from the conical section 7 of the solids collecting hopper, along the solids discharge pipe and into the central solids collector vessel 9, can be established without the need for additional conveying means to transfer the collected solids to the central collector~ Furthermore, the discharge from the collector vessel 9 can be by way of pneumatic conveying using the gas pressure prevailing in the cyclone separator ehamber 1 as the conveying gas (in this case approximately 1% of the discharge gas flow entering the cyclone separator assembly will be used for conveying away the solids in the form of a pneumatically eonveyed stream).
Alternatively, a valve may be provided at the bottom of the solids collector vessel 9 and equipped with some form of air lock to preserve gas pressure within the colleetor vessel g while allowing intermittent discharge of the collected solids onto a mechanical conveyor for disposal.
For example the eollector vessel 9 may discharge through a first shut-off valve, into a disentrainment hopper whose outlet ineludes a second shut-off valve.
Figures 3A and 3B exempli.fy the advantages which can be derived using the cyclone separator assembly shown in Figures 1 and 2.
Figure 3A illustrates a conventional energy recovery system in a fluid catalytic cracker unit and shows r ,~
.'. ,. ~
~3 ~Z1743 that the regenerator vessel 10 includes both primary and secondary separators 11 and 12, respectively, of conventional form feeding a discharge pipe 13 leading to a waste heat boiler 14. The spent flue gas from the boiler 14 i~ discharged through flue 15 while water heated in the boiler is converted to steam in the line 16 to be fed to the inlet of a steam turbine 17. The shaft of the steam turbine 17 is linked to an air compressor 18 to supply air to the înlet feed to the regenerator vessel 10.
In the e~ample of Figure 3A, if the efficiency of the waste heat boiler is assumed to be 30%, and the efficiency of the combination of steam turbine 17 and compressor 18 (14%), then for every one hundred units of heat energy in the stream passing along pipe 13 from the regenerator chamber 10, thirty of these units are present in the steam line 16 and only four of these units of energy will be evident in the line from the air compressor 18.
Since the feed to the catalytic cracking regenerator chamber 10 requires twelve units o heat in the air supply~ eight of the units, i.e. 8% of the energy requirement, must be supplied from outside the system by external topping up.
A much more efficient way of recovering the energy in the line 13 can be appreciated from the alternative system illustrated in Figure 3 B where again the regenerator chamber 10 has primary and secondary 7'~3 cyclone separators 11 and 1~ of conical design, with the secondary conical cyclone separators 12 feeding a discharge line 13. This discharye line feeds a separating system 19 which is in fact the assembly or cluster of individual cyclone separating vessels 1 illustrated in Figures 1 and
2 and runs with a very high separating efficiency. The solids content is removed from the discharge flow and then the flow passes on from the separating cluster 19 into a discharge line ~ towards the gas turbine 17aO
~ow that there has been no pressure loss due to the escape of flue gases ~as through flue 15 in Figure 3A) the pressure in the feed to the gas turbine 17a is much higher and so also will be the pressure in the discharge line 21 from the turbine 17a. This discharge gas stream from the turbine 17a can therefore enter the waste heat boiler 14a where again the heat energy is used to generate a flow of steam in line 16a while the waste gas is e~hausted through the flue 15a. The gas turbine 17a is linked directly by its output shaft to the input shaft of a primary air compressor 18a which supplies the total air feed requirements for the cracking regenerator chamber 10. Alternatively the turbine 17a may dri~e an electric generator for supplying electrical power for use on plant or for other purposes.
7'~3 The steam from the waste heat boiler feeds a steam turbine 17b from which part of the inlet air supply is generated by means of the directly coupled secondary air compressor 18bo The degree of efficiency of the revised system shown in Figure 3B is such that of every one hundred units of energy leavi.ng the regenarator chamber 10, twelve units will appear in the flow of air from the primary air compressor 18a into the regenerator chamber 10, while a further three units of energy will appear in the air flow from the secondary air compressor 18b.
A simple comparison of the result of the two systems shown in Figures 3A and 3B indicates that whereas in Figure 3A the energy recovery system was capable of meeting only 1/3 of the energy input requirements for the chamber 10, the system in Figure 3B enabled the primary compressdr 18a alone to meet the full energy requirements, and the secondary compressor 18b offered a surplus energy availability corresponding to 1/4 of the total energy requirements for the reactor 10 (i~e~ three units as compared with the energy require-ment of twelve units for the regenerator 103O
The system of Figure 3B is an idealised situation which has been unattainable in practice due to 1~17~3 the difficulty of combatting erosion in the primary exhaust gas turblne 17a. It has been known in the past for turbines protected by a prior art cyclone separator system, to become useless after a runnlrlg time of a mere eight hours due to erosion occurring within the conical cyclone separators~
In a practical example using the cyclone separator assembly in accordance with the present invention, a fluid catalyticcracking unit regenerator discharging solids-laden gas at a pressure of 2.5 atmospheres absolute was arranged to feed a cluster of 16 cylindrical cyclone separator vessels 1 arranged to be fed from the common exhaust line 13 (Figure 3B)~ The cluster of vessels 1 (equivalent to the schematically ~: 15 illustrated cyclone separator 19 in Figure 3B) then had its gas discharge passed through conduit 6a to a common feed line into the gas turbine 17a. Because of the much higher efficiency of separation afforded by the cyclone separator assembly in accordance with the present invention, the turbine life has been extended to a considerable extentO For example, there was no measurable loss of turbine efficiency after 27,000 hours running time.
With the cyclone separator assembly in accordance with the present invention it is generally true that the solids carryover in the air exik l.ine from the separators r~, 7~3 has only 5% in the form of particles la:rger than 10 microns in diameter.
In one particular example, the analysis of the particles dischargedfrom the cyclone separator assembly in accordance with the invention was such that 95% of the carryover was less than 10 microns:~ 94% of the carryover was known to have been less than 5 microns, and 92.5% was less than 2.5 micronsO Since particles of two microns or less i.n diameter pass through a power recovery turbine without even impacting the blades, it is clear that the efficiency of separation made possible by the cyclone separator assembly of the present invention is adequate for providing a satisfactory life to the turbine. Equally, it is known that particles of 10 : -microns or more are certain to contact a blade at some stage during a pass through a power recovery turbine and the fact that a mere 5% of the carryover is likely to be greater than 10 microns provides evidence of the fact that there is a very low likelihood of blade damage by particle impact~
..
~ow that there has been no pressure loss due to the escape of flue gases ~as through flue 15 in Figure 3A) the pressure in the feed to the gas turbine 17a is much higher and so also will be the pressure in the discharge line 21 from the turbine 17a. This discharge gas stream from the turbine 17a can therefore enter the waste heat boiler 14a where again the heat energy is used to generate a flow of steam in line 16a while the waste gas is e~hausted through the flue 15a. The gas turbine 17a is linked directly by its output shaft to the input shaft of a primary air compressor 18a which supplies the total air feed requirements for the cracking regenerator chamber 10. Alternatively the turbine 17a may dri~e an electric generator for supplying electrical power for use on plant or for other purposes.
7'~3 The steam from the waste heat boiler feeds a steam turbine 17b from which part of the inlet air supply is generated by means of the directly coupled secondary air compressor 18bo The degree of efficiency of the revised system shown in Figure 3B is such that of every one hundred units of energy leavi.ng the regenarator chamber 10, twelve units will appear in the flow of air from the primary air compressor 18a into the regenerator chamber 10, while a further three units of energy will appear in the air flow from the secondary air compressor 18b.
A simple comparison of the result of the two systems shown in Figures 3A and 3B indicates that whereas in Figure 3A the energy recovery system was capable of meeting only 1/3 of the energy input requirements for the chamber 10, the system in Figure 3B enabled the primary compressdr 18a alone to meet the full energy requirements, and the secondary compressor 18b offered a surplus energy availability corresponding to 1/4 of the total energy requirements for the reactor 10 (i~e~ three units as compared with the energy require-ment of twelve units for the regenerator 103O
The system of Figure 3B is an idealised situation which has been unattainable in practice due to 1~17~3 the difficulty of combatting erosion in the primary exhaust gas turblne 17a. It has been known in the past for turbines protected by a prior art cyclone separator system, to become useless after a runnlrlg time of a mere eight hours due to erosion occurring within the conical cyclone separators~
In a practical example using the cyclone separator assembly in accordance with the present invention, a fluid catalyticcracking unit regenerator discharging solids-laden gas at a pressure of 2.5 atmospheres absolute was arranged to feed a cluster of 16 cylindrical cyclone separator vessels 1 arranged to be fed from the common exhaust line 13 (Figure 3B)~ The cluster of vessels 1 (equivalent to the schematically ~: 15 illustrated cyclone separator 19 in Figure 3B) then had its gas discharge passed through conduit 6a to a common feed line into the gas turbine 17a. Because of the much higher efficiency of separation afforded by the cyclone separator assembly in accordance with the present invention, the turbine life has been extended to a considerable extentO For example, there was no measurable loss of turbine efficiency after 27,000 hours running time.
With the cyclone separator assembly in accordance with the present invention it is generally true that the solids carryover in the air exik l.ine from the separators r~, 7~3 has only 5% in the form of particles la:rger than 10 microns in diameter.
In one particular example, the analysis of the particles dischargedfrom the cyclone separator assembly in accordance with the invention was such that 95% of the carryover was less than 10 microns:~ 94% of the carryover was known to have been less than 5 microns, and 92.5% was less than 2.5 micronsO Since particles of two microns or less i.n diameter pass through a power recovery turbine without even impacting the blades, it is clear that the efficiency of separation made possible by the cyclone separator assembly of the present invention is adequate for providing a satisfactory life to the turbine. Equally, it is known that particles of 10 : -microns or more are certain to contact a blade at some stage during a pass through a power recovery turbine and the fact that a mere 5% of the carryover is likely to be greater than 10 microns provides evidence of the fact that there is a very low likelihood of blade damage by particle impact~
..
Claims (12)
1. Apparatus for separating solid particles from a gas stream comprising a plurality of cyclone separator vessels connected in parallel to be fed from a common gas source and to discharge to a common gas outlet, each of the cyclone separator vessels having a cylindrical separator chamber of substantially uniform internal diameter along its length of from 20 inches to 40 inches, and being provided with means for discharging the separated solid particles from the bottom of the said cylindrical separator chamber.
2. Apparatus according to claim 1, wherein the range of internal diameters of the said cylindrical separator chambers is from 24 inches to 36 inches.
3. Apparatus according to claim 2, wherein the internal diameter of each said cylindrical separator chamber is 30 inches.
4. Apparatus according to claim 1, 2 or 3, wherein each of the said cylindrical separator chambers is formed of austenitic steel without any inner anti-erosion lining.
5. Apparatus according to claim 1 wherein each cyclone separator vessel has a respective collecting hopper for separated solid particles, which hopper discharges to a collector vessel for separated solid particles for centralised removal of the separated solid particles.
6. Apparatus according to claim 5, wherein each cylindrical cyclone separator has a respective said collecting hopper for separated solid particles attached to the lower end of the cylindrical separator chamber and the said cylindrical separator chamber opens into the collecting hopper for separated solid particles at a location spaced below the top of the collecting hopper for separated solid particles so as to allow the swirling solid particles to be flung radially outwardly from the gas vortex in the cy-lindrical separator chamber, thereby to separate from the gas stream which can then escape vertically upwardly along the core of the vortex towards a gas discharge duct at the top of the cylindrical separator chamber.
7. Apparatus according to claim 6, wherein all of the cyclone separator vessels are fed from a common inlet manifold and the discharge to said common gas outlet is by means of one or more gas discharge manifolds.
8. Apparatus according to claim 1, 2 or 3 wherein said common gas source is the exhaust duct from a catalytic cracking unit regenerator, and is subjected to a system pressure; the individual said cylindrical separator chambers are each pressurized to the same pressure as said exhaust duct; said separated solid particle discharging means include respective solids discharge pipes from the cyclone separator vessels to a collector vessel; and said system pressure is maintained along each said solids discharge pipe.
9. Apparatus according to claim 1, 3 or 7 wherein the various cyclone separator vessels are incorporated in a main pressure vessel.
10. Apparatus according to claim 1, when connected to a fluidised catalytic cracker unit serving as said common gas source.
11. Apparatus according to claim 10, wherein the said f1uidised catalytic cracker unit includes a catalyst regenerator vessel and it is the catalyst regenerator vessel of the fluidised catalytic cracker unit which serves as said common gas source.
12. Apparatus according to claim 11, wherein said common gas outlet is connected to a power recovery turbine driving an air compressor supplying air to the catalyst regenerator vessel of the fluidised catalytic cracking unit.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB15141/76A GB1528658A (en) | 1976-04-13 | 1976-04-13 | Gas/particle separating apparatus and method |
| GB15141/76 | 1976-04-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1121743A true CA1121743A (en) | 1982-04-13 |
Family
ID=10053778
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000275997A Expired CA1121743A (en) | 1976-04-13 | 1977-04-12 | Gas/particle separating device |
Country Status (3)
| Country | Link |
|---|---|
| CA (1) | CA1121743A (en) |
| GB (1) | GB1528658A (en) |
| ZA (1) | ZA772247B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4687497A (en) * | 1986-09-29 | 1987-08-18 | Mobil Oil Corporation | Solids-gas separator |
-
1976
- 1976-04-13 GB GB15141/76A patent/GB1528658A/en not_active Expired
-
1977
- 1977-04-12 CA CA000275997A patent/CA1121743A/en not_active Expired
- 1977-04-13 ZA ZA00772247A patent/ZA772247B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| GB1528658A (en) | 1978-10-18 |
| ZA772247B (en) | 1978-03-29 |
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