Because Fluid CokingTM is a process in which solids circulation takes place, the new lab-scale cold flow recirculating fluidized bed was designed with a standpipe and a riser for solids recirculation. The test material is coke provided by Syncrude Canada Ltd.; and air is used to fluidize the coke.
The diameters of the stripper and standpipe of the fluidized bed are geometrically similar to those of Cui et al. (2006), but scaled down by a factor of 1/10 (impingement box scaled with a factor of 1/33). Figure 3-1 presents the design [Figure 3-1-a)] and final construction of the setup [Figure 3-1-b)], the stripper section has an outside diameter (O.D.) of 20.32 cm (8 in) and a wall thickness of 0.64 cm (¼ in); the standpipe has an O.D. of 7.62 cm (3 in) with the same wall thickness. The impingement box has an O.D. of 30.48 cm (12 in) with a wall thickness of 0.64 cm (¼ in). These components were fabricated from acrylic (Johnson Industrial Plastics Edmonton, Alberta) and constructed at the University of Saskatchewan Engineering workshop.
a) b)
Figure 3-1. a) Blueprint of the new fluidized bed. b) New fluidized bed photo.
The riser section, which connects the standpipe outlet to the inlet of the impingement box, is fabricated from a single, clear, flexible, food grade 185.42 cm (73
Horizontal Angle Frames
Height Coordinate Z 0.00cm
in) PVC tube supported by a clear, rigid PVC helix obtained from Green Line (Saskatoon, Saskatchewan, Canada). To control the solids flow of solids that circulates through the riser a 6.35 cm (2 ½ in) pinch valve from EVR (Sudbury, ON) is used at the bottom of the fluidized bed. Below the pinch valve exists a ball valve, for quick solid shutdown and later there is a quick connector “T” to retrieve the fluid material and radioactive tracer-agglomerate in a fast, clean and secure way. The external frame is made of 5.08 cm x 5.08 cm (2 in x 2 in) angle iron. In addition, one 0.64 cm (¼ in) thick iron sheet, 92.71 cm x 92.71 cm (36 ½ in x 36 ½ in), is used as a base for the scintillation detectors. It also has three 5.08 cm x 5.08 cm (2 in x 2 in) horizontal angle frames [Figure 3-1-b)] to support the tensors, which was used to raise and lower the upper section of the bed; the iron sheet (in the middle of the setup), where the detectors are mounted; and the frame that support the valve that is used to control the flow of solids. Six metal vertical structures to mount the detectors are placed at 60 ° angles around the periphery of the stripper section.
The riser entered into the bed from the top, and into a 6.35 cm (2 ½ in) 90 degree elbow (tangential to the bed) in order to create a circular motion mimicking the entrance of a cyclone, in order to minimize losses of coke to the cyclone.
The fluidization gas is a compressed air coming from the Institute for Chemicals and Fuels from Alternative Resources (ICFAR) compressors. The setup has three valves that supply air to the fluidized bed (one for air going to the standpipe, another one for air going to the sparger and a third one that works as a relief valve). Two orifice plates, for measuring the air flow, are located in a long copper pipe of 5.08 cm (2 in) diameter {0.64 cm (¼ in) orifice for the sparger and 3.18 cm (1 ¼ in) for the riser}, both constructed in accordance with McCabe et al. (1993) design guidelines. In order to measure the flow rates of air through the sparger and through the standpipe with these two orifice meters, two U-tube water manometers are installed at the side of the fluidized bed.
Figure 3-2 displays the sparger loop, which supplies compressed air to fluidize the bed inside the reactor. It consists of two loops (one internal and one external) in order to equalize the pressure along the sparger. The internal loop has nine 1.59 cm (5/8 in)
diameter holes per side [constructed using the distributor design guidelines presented by Kunii and Levenspiel (1991)] covered with mesh to prevent particles from entering the sparger tube when the bed is not operating. In order to connect the blower setup to the fluidized bed, two flexible hoses with quick connectors are used. The bed is equipped with wheels that have brake assemblies, so they can easily be moved around the pilot plant.
Figure 3-2. Sparger loop air feedstock.
The fluidized bed operates with two rows of sheds in the middle of the measurement zone. The top sheds reduce the cross sectional area by 47.4%, and the bottom sheds reduce the cross sectional area by 40.4 %. The sheds are constructed from a single 2.54 cm (1 in) thick round acrylic block. The sheds are mounted on an apron with the edges “sandwiched” between flanges. This design has four sets of tensors that enables the lift of the upper part of the bed and allows easy removal of the shed rows, which is important for the present work because different sheds or baffle geometries will be tested.
Figure 3-3. Fluidized bed apparatus components and instrumentations: (1) Compressed
air inlet; (2) orifice plates for flow measurement; (3) ball valves; (4) pinch valve; (5) elbow pressure taps for solids flow measurement; (6) 6.35 cm I.D. riser
(8) three top-row sheds and two complete I.D. disengagement zone; (10) cyclone; (11)
detectors in a four layer array; (13) USB hubs; (14) slave computers; (15) Ethernet hub and (16) server computer.
Twelve NaI scintillation sensors (Advance Measurement Technology, Inc., Ridge, TN) surround the
layer. The detectors communicate with the computer via two Adaptec (Milpitas, CA, U.S.A.) and two 4
accelerate data acquisition
T41), which run a program created in the LabWindows CVI p Instruments, Austin, TX)
(depending on the radiation emitted by the tracer). The “ (Dell Inspiron N5040) timestamp
so that they all take a reading at the same time and send
zed bed apparatus components and instrumentations: (1) Compressed air inlet; (2) orifice plates for flow measurement; (3) ball valves; (4) pinch valve; (5) elbow pressure taps for solids flow measurement; (6) 6.35 cm I.D. riser; (7) loop sparger; row sheds and two complete bottom-row shed plus two half; (9) 29.21 cm I.D. disengagement zone; (10) cyclone; (11) γ-rays emitter; (12) twelve NaI Scintillation
detectors in a four layer array; (13) USB hubs; (14) slave computers; (15) Ethernet hub and (16) server computer.
Twelve NaI scintillation sensors (Advance Measurement Technology, Inc., Ridge, TN) surround the fluidized bed in an array of four layers of three sensors per layer. The detectors communicate with the computer via two Adaptec XHub
(Milpitas, CA, U.S.A.) and two 4-StarTech USB hubs, three sensors per hub. To cquisition (DAQ), four “slave” (or client) computers (IBM ThinkPad run a program created in the LabWindows CVI platform (National Austin, TX), collect the detectors signals every 12 to 25 milliseconds (depending on the radiation emitted by the tracer). The “server” (or m
(Dell Inspiron N5040) timestamps the DAQ event and synchronies the
at they all take a reading at the same time and send the information back
zed bed apparatus components and instrumentations: (1) Compressed air inlet; (2) orifice plates for flow measurement; (3) ball valves; (4) pinch valve; (5) ; (7) loop sparger; row shed plus two half; (9) 29.21 cm rays emitter; (12) twelve NaI Scintillation detectors in a four layer array; (13) USB hubs; (14) slave computers; (15) Ethernet hub
Twelve NaI scintillation sensors (Advance Measurement Technology, Inc., Oak fluidized bed in an array of four layers of three sensors per XHub-7plus hubs StarTech USB hubs, three sensors per hub. To lient) computers (IBM ThinkPad latform (National collect the detectors signals every 12 to 25 milliseconds master) computer the DAQ event and synchronies the client computers information back to the
server computer. Figure 3-3 presents the schematics of the complete fluidized bed with all its components.
The bed is equipped with five pressure taps that are located in the measurement zone of the fluidized bed to measure the axial pressure profile along the bed [Figure 3-4- a)]. In addition, the bed is equipped with a National Instruments USB-6008 DAQ and with Omega PX16X pressure transducers to measure the differential pressures [Figure 3-4-b)]. The collected data is stored and processed with an IBM Lenovo ThinkCentre with two Intel core CPU processors 6400 at 2.13 GHz.
a) b)
Figure 3-4. a) Pressure taps along the fluidized bed. b) NI-DAQ and pressure
transducers.
A set of pressure taps are located in the elbow [Figure 3-5-a)], in order to measure the flowrate of solids flowing into the riser. The solids flow was calibrated with a non- mechanical valve [Figure 3-5-b)] that uses the angle of repose to interrupt the flow of solids above the shed zone: the rate of removal of solids from the fluidized bed below the valve was determined by measuring the time it took the bed surface to drop by about 18 cm and using the change in bed pressure drop to determine the accurate solids flowrate into the recirculating line and through the elbow. The calibration was performed by changing the air velocity that flows in the riser, as well as the pressure drop measured from the elbow pressure taps (this variable was modified, by adjusting the pinch valve at
the bottom of the fluidized bed). Equation (3.1) presents the result of the calibration of solids as a function of these two variables.
a) b)
Figure 3-5. a) Pressure tap to measure the flow of solids in the riser. b) Non-mechanical
valve to divide the bed in two. P U P U P U P U P U P U F r r r r r r s ∆ + ∆ − ∆ + − ∆ − ∆ − + ∆ + − = 2 2 3 3 2 2 007 . 0 002 . 0 03 . 0 005 . 0 07 . 0 14 . 0 11 . 0 65 . 0 85 . 0 10 . 2 (3.1) Where:
• Fs is the flow of solids in kg/s.
• Ur is the air velocity in the riser measured with the orifice plate/water manometer • ∆P is the pressure drop measured with the elbow orifice taps.