TECHNICAL FIELD

The present invention relates in general to production of coke pieces having a size suitable for handling in further use thereof.

In more detail, the present invention relates to a coke crusher that is suitable for producing such coke pieces from large petroleum coke chunks cut from a coke drum of a delayed coker. There is a co-pending patent application PCT/EP201 1 /062061 of July 14, 201 1 , titled

"Closed Coke Slurry System and Method for Gaining Sellable Petroleum Coke Pieces Out of Solidified Petroleum Coke in a Coke Drum Unit", filed by the same applicant of the present application, the disclosure thereof shall herein be incorporated by reference. A coker is part of a refinery that converts residual oil from the crude unit vacuum or atmospheric column into gas oil that can be made into light products, weak fuel gas and petroleum coke. The liquid petroleum coke solidifies as it cools. Usually solidification takes place in coke drums. Once such drum is filled with solidified coke, the coke drum is steamed to further reduce hydrocarbon content of the petroleum coke, and water quenched for cooling. Then, top and bottom heads of the coke drum can be removed, i.e. the drum can be unheaded, to ream out the solidified petroleum coke from the coke drum by hydrodynamic cutting. The cutting process produces inter alia large chunks of petroleum coke. From the coke drum outlet the so-called "green petroleum coke" may be transferred directly into rail cars or into a pit or pad with cranes or end loaders for further handling, e.g. further processing such as calcification or selling. The produced petroleum coke chunks widely vary in size. However, large chunks are not optimal for further handling, i.e. large chunks of petroleum coke need to be reduced to smaller pieces.

It is well known to pulverize various materials by compression between rotating drums of a so called rolling drum crusher. Indeed, the use of rolling drum crushers for crushing petroleum coke is basically known. But a crusher for petroleum coke in a coking unit of a refinery has to face rough conditions. For instance, in a delayed coker system as disclosed in the above-incorporated patent applications a coke slurry portion of the system is preferably closed to the environment. Further, usually such refineries are struggling to reach best productivity and thus, are continuously operated. Therefore, any forced stoppage of the coking unit caused by a faulty coke crusher is significantly harming productivity. Thus, it may be an objective of the present invention to provide an improved coke crusher suitable for use in a refinery, particular in a coker unit thereof for crushing coke.

One or all of the above problems is/are alleviated, or, one or all of the above objects are solved by the features of the independent claims. Further embodiments and developments are defined by the respective dependent claims.

Accordingly, a coke crusher for crushing petroleum coke is basically configured for installation underneath a respective coke drum so that coke chunks cut out of the coke drum during decoking can be fed directly into an inlet of the crusher. In this vertical configuration coke chunks aggregate just on and above the crusher rolls and form a coke column of coke chunks. The coke column, on the one hand, supports feeding the coke chunks into the crusher by means of its own weight, but, on the other hand, the crusher is subject to high input loads.

Basically, the coke crusher comprises a main housing and a pair of crushing rolls arranged in said main housing for rotation about parallel axes. Said crushing rolls are cylindrical shaped and have a predetermined diameter and a predetermined spacing from each other so as to define a crushing window there between, i.e. between the rolls.

According to an aspect, each of said crushing rolls is toothed by comprising on its cylinder surface a predetermined pattern of seizing teeth and crushing teeth. Each of said teeth, i.e. seizing and crushing teeth, projects radially with a maximum height of up to half of the predetermined spacing, i.e. the crushing rolls are arranged such that the teeth of the opposed crushing rolls do not mesh in operation. By this feature the crushing rolls of the crusher can be individually operated so as each crushing roll can rotate with an individual number of rotations per minute, i.e. with different rotational speeds .In this connection, it has been found that without meshing between the teeth of the opposite crusher rolls the crusher produces less amount of coke fines. It is assumed, when the teeth of the crusher rolls do not mesh, grinding of coke pieces between meshing teeth does not take place; such grinding would generate smaller coke pieces as well as more coke fines.

According to a further aspect, the seizing and crushing teeth respectively comprise a tip configuration with beveled compression surfaces that beveled compression surfaces basically have a wedge-like shape providing for a wedge effect. Thus, the teeth disintegrate the coke chunks in the crushing window rather by splitting and cleaving than by sole compression that would happen between only flat or plane surfaces of opposite crushing roll surfaces.

That is to say, the wedge effect tip configuration together with non-meshing teeth between the two crusher rolls achieves a significant reduction of generated coke fines. Further, said seizing teeth are configured so as in operation of the crusher coke chunks are nipped and dragged into said crushing window by means of said seizing teeth and shattered and disintegrated between said crushing rolls into coke pieces of a predetermined maximum size corresponding to said predetermined spacing by means of said seiz- ing teeth and said crushing teeth.

In certain embodiments, each of said seizing teeth comprise a shovel blade-like operating portion that is directed into the respective direction of rotation of the respective crushing roll. Said shovel blade-like operating portion may be tilted into the respective direction of rotation, i.e. the shovel blade-like operating portion encloses a clearance angle or operating angle smaller 90 degrees with the respective surface of the respective crushing roll. The inclination of the seizing teeth into the direction of rotation, i.e. the clearance angle, further improves the efficiency of the crusher by improved discharging or sliding coke chips away from the seizing teeth which are produced by the seizing teeth cutting and milling the coke chunks that are pressed onto the crushing rolls by the weight of the cokes chunk column.

Further, each of said seizing teeth may comprise a pointing tip, which forms the most extending part of said seizing teeth with respect to the respective surface of the respective crushing roll and a leading point of the seizing tooth with respect to the respective direction of rotation. Furthermore, each of said seizing teeth may be configured with, in particular three, inclined compression surfaces that run from said tip with a decreasing distance to the respective surface of the respective crushing roll, i.e. said inclined compression surfaces are beveled with respect to the respective surface of the respective crushing roll. In a particular embodiment, one of the compression surfaces is a trailing surface with respect to the direction of rotation and is oriented basically parallel to the respective axis of rotation; the other two inclined compression surfaces form with respect to the axial direction of the respective crushing roll a left and a right compression surface, that respectively run transversely to the respective axis of rotation. The inventors have found that by having seizing teeth comprising the tip and the inclined compression surfaces the effect of disintegration of coke chunks is primarily caused by the wedge effect of the teeth instead of compression. It is assumed that this further reduces the generated amount of coke fines since the coke chunks are primarily splinted. In certain embodiments, each of said crushing teeth comprise a wedge-like operating portion that is directed into the respective direction of rotation of the respective crushing roll, i.e. forms a leading edge of the respective crushing tooth. Further, each of said crushing teeth may comprise a tip, which forms the most extending part of the respective crushing tooth with respect to the respective surface of the respective crushing roll, whereby the leading edge runs form the tip down to the surface of the crushing roll. A further aspect of the crusher concerns configuration of the crusher input, i.e. upstream inlet. In certain embodiments, the crusher comprises an upstream inlet arranged at or part of an inlet unit attached to the main housing.

Said upstream inlet may comprise a, e.g. circular-shaped, input opening for receiving coke chunks to be crushed. Said inlet is adapted so as to direct the coke chunks onto said crushing rolls. The input opening can be centered beyond the predetermined spacing, i.e. the center of the inlet is located over said crushing window. The inlet may have a diameter that corresponds to the length of said crushing rolls; thereby the full length of the crushing window can be charged with petroleum coke chunks produced in the decoking process.

Further, preferably the edges of the inlet opening as viewed from the side in direction of the axes of rotation are respectively located just over a respective one of the axes of rotation of the crushing rolls. Thus, the crushing rolls have to move coke chunks only into the direction of gravity when moving coke chunks towards the crushing window.

In certain embodiments, the crusher may comprise a, in particular telescopic, chute for coupling the upstream inlet of the crusher to a bottom outlet of a coke drum or an automatic unheading unit mounted to the bottom outlet of the coke drum. Preferably, such chute comprises, preferably at the end opposite to the crusher, an, in particular circular, input aperture; in other words, the input aperture is preferably located at the upstream inlet of the chute and thus, adjacent to the outlet flange of the coke drum. The input aperture is configured to reduce an inner diameter of the chute so as a ratio of the input diameter of the input aperture to the spacing of the crushing rolls corresponds to the crushing ratio of the crusher. Thereby, only coke chunks having a size that the crusher is designed to disintegrate may pass through the chute into the crusher inlet opening.

For example, it may happen that coke chunks having a size greater as the predetermined maximum input size are produced during ream out of the coke drum. Such coke chunks could block the crusher but will already be withheld at the input aperture. In such a case the on-going crushing operation of the crusher will empty the inner space of the chute so that the withheld coke chunks may easily cut by means of the coke cutting means used in the coke cutting process for decoking the coke drum. Thus, the coke crusher can be reliable operated continuously without getting blocked.

In a particular embodiment the crushing ratio of the crusher is 10 to 1 . Thus, in accordance with the afore-mentioned design criterion, the input aperture is configured to have a diameter that is ten times of the predetermined spacing of the crushing rolls, i.e. the width of the crushing window. Thus, it is secured that the crushing rolls are charged with that maximum chunk size only the crusher is designed to disintegrate. In this particular embodiment, the crusher is configured to disintegrate coke chunks up to 10 times bigger as the predetermined crushing window. A particular feature of the crusher is the two tooth types, i.e. the seizing teeth and the crushing teeth, which preferably are both integral elements of said crushing rolls. In certain embodiments the seizing teeth and the crushing teeth are arranged alternately on parallel circumferential lines being perpendicular to the respective axis of rotation of said crushing rolls. Preferably, the teeth of each type are regular spaced to each other on the circumferential lines. Further, it has been found that the alternating arrangement of seizing and crushing teeth also leads to further reduction of produced coke fines.

One further aspect concerns the configuration of the two types of teeth as well as the arrangement of said teeth, i.e. the tooth pattern, on the crushing rolls.

In one embodiment said seizing teeth and crushing teeth, respectively, are arranged aligned and regular spaced in axial direction of said crushing rolls. In other words, the crushing rolls comprise axial rows of teeth of the same type.

In another embodiment said seizing teeth and crushing teeth, respectively, are arranged alternately and regular spaced also in the axial direction of said crushing rolls. In other words, the crushing rolls comprise axial rows of teeth of both types in an alternating sequence. Thereby, each kind of tooth of the tooth pattern on the crusher rolls is part of a V-shaped tooth formation where the tip of the "V" is pointing into the direction of rotation of the respective crusher roll. It has been found that the tooth pattern with V-shaped formation provides for a further improved drag-in ability of the crusher. Moreover, it has been found that the alternating arrangement of seizing and crushing teeth in the axial direction of said crushing rolls also provides for a further reduction produced coke fines.

Preferably, the crushing teeth have a smaller height as the seizing teeth. Good results have been achieved with seizing teeth having a height of around 80% to 95% of the half of the width of the crushing window of the crusher and crushing teeth having a height around 50% to 60% of the height of the seizing teeth.

In particular embodiments, each of said crushing teeth is a conic solid. Thus, each crushing tooth has a tip or apex and provides beveled compression surfaces with respect to the crushing roll, which beveled compression surfaces provide for a wedge effect by which coke chunks in the crushing window are rather splinted by cleaving than pulverized by compression. Preferably, the conic solid has an oblique axis that is tilted into the rotational direction of the respective crushing roll. By means of the oblique configuration also the crushing teeth support the nipping and dragging effect of the seizing teeth once coke chunks some in the sphere of influence of the crushing teeth.

In certain embodiments each crushing tooth comprises a pyramidal shape having a quadratic base that corresponds to an interface to the crushing roll. The base has four corners, two of which are located on a line that is perpendicular to said axis of rotation of said crushing rolls. By this particular orientation of the crushing tooth on the crushing rolls, each crushing tooth comprises a leading edge that runs from the surface of the respective crushing roll to the apex of the pyramid, which provides for a wedge effect supporting the fragmentation of the coke chunks between the crushing rolls. Moreover, it has been found that by means of the oblique configuration of the pyramid shaped crushing teeth, the teeth are more resistant to shearing forces.

In one embodiment, the base of the conic solid comprises four edges with a length of about 40 mm (1 .57 in). Further, respective opposite ones of the four corners are spaced by about 50 mm (1 .97 in). Furthermore, the base point of the oblique axis and the base point of the height of the conic solid are spaced by about 5 mm (0.20 in). Moreover, all crushing teeth comprise an equal height, which is about 35 mm (1 .38 in).

In particular embodiments, each of said seizing teeth is comprised of a truncated first conic solid as main body and a tip thereon formed by a second conic solid. Thus, each seizing tooth has the second conic solid as tip that provides beveled compression surfaces with respect to the crushing roll. The beveled compression surfaces of the seizing teeth also provide for the mentioned wedge effect by which coke chunks in the crushing window are rather splinted by cleaving than pulverized by compression. The truncated first conic solid preferably has a first oblique axis and the second conic solid preferably has a second oblique axis. Both first and second oblique axes are both tilted into the rotational direction of the respective crushing roll. By this configuration the seizing teeth comprise the clearance angle that provides for discharging or sliding coke chips away from the seizing teeth. Such coke chips are produced by the seizing teeth when cutting and milling the coke chunks pressed onto the crushing rolls by pressure caused by the weight of the cokes column loaded onto the crusher.

In certain embodiments, each seizing tooth comprises a rectangular base that corresponds to an interface to the crushing roll. The rectangular base comprises four edges, two of which are preferably located parallel to any circumferential line on the respective crushing roll being perpendicular to said axes of rotation of said crushing rolls. By this particular orientation of the seizing teeth, both the truncated first conic solid and the second conic solid on top provide a respective leading surface facing and being tilted into the rotational direction of the corresponding roll. Preferably, both respective leading surfaces of the truncated first conic solid and the second conic solid are part of a common plane. The leading surface of the seizing teeth provides for a working surface for nipping the input coke chunks.

In one embodiment, the base of the truncated first conic solid is rectangular and comprises two longitudinal edges being parallel to said circumferential line and having an equal length of about 60 mm (2.36 in) and two cross-edges having an equal length of about 50 mm (1 .97 in). Further, the base of the second conic solid, i.e. the interface to the main body, is also rectangular with two longitudinal edges having equal length of about 25 mm (0.98 in) and two cross-edges with equal length of about 40 mm (1 .57 in). Furthermore, all seizing teeth comprise an equal total height of about 60 mm (2.36 in), whereby the truncated first conic solid has a height of about 50 mm (1 .97 in) and the second conic solid has a height extending from the interface plane to the truncated first conic solid of about 10 mm (0.39 in).

Preferably, all teeth on the crushing rolls comprise smooth transition surfaces between said respective tooth and the surface of the corresponding crushing roll. Most preferably, the transition surfaces have a common transition radius of preferably 10 mm (0.39 in).

Preferably, each of said crushing rolls is casted integrally with said seizing and crushing teeth. In a certain embodiment the crushing rolls made as a cast hollow drum with respective axial abutting faces which comprise respective axial bushings for receiving a respective driving shaft coupled to the respective driving means. Inside the crushing drums there may be provided supporting elements to stiffen the cylinder-shaped wall of the crushing roll drum.

As mentioned above, each of the two crushing rolls comprises a predetermined number of circumferential lines with a respective predetermined number of alternating seizing teeth and crushing teeth. In one embodiment, each crushing roll comprises preferably nine circumferential lines of teeth and each of said circumferential lines comprises preferably twenty seizing teeth and twenty crushing teeth.

A further aspect of the invention concerns the installation of the crushing rolls into the main housing to establish the roll crusher.

In particular embodiments, the main housing comprises respective shaft openings for passing through respective ends of said driving shafts for rotating the associated crushing roll coupled to the associated shaft. Further, the crusher comprises respective bearing units removable mounted outside the main housing adjacent to the respective shaft openings. Each bearing unit is adapted for receiving a respective one of the ends of said driving shafts. By this configuration, the driving shafts can be removable installed by inserting the shaft from one side through a first one of said shaft openings, then through the associated crushing roll already located inside the main housing, and next through the second one of said shaft openings opposite to the first one. Finally, at each of said respective ends of the driving shafts one respective bearing unit is installed for supporting the rotating driving shafts in operation. Each of the driving shafts, at one end thereof, is passed through the respective bearing unit to be coupleable to an associated driving means. In one embodiment, respective hydraulic motors are coupled as driving means for rotating the crushing rolls in operation.

In certain embodiments, each of the crushing rolls is individually driven by means of its own driving means, e.g. as mentioned by means of an individual hydraulic motor. Thus, in operation the crushing rolls can perform an individually controlled rotation in opposite, i.e. counter-wise, directions. Further, the inventors have found that it is not necessary that the rotation of the crushing rolls is synchronously timed. Indeed, it has been found that a relative motion between the crushing rolls can be advantageous, particular in the case of soft coke types, where it has been found that the crusher can be operated more efficiently when the crushing rolls are operated at different rotational speeds, i.e. rotations per minute. Thus, it is a further advantageous feature of the crusher that the rotational speed of each crushing roll can be controlled individually.

Preferably, at each driving shaft one first bearing unit is a self-aligning radial bearing with an inner ring that moves independently of an outer ring - like a cylindrical roller bearing - enabling the driving shaft to move smoothly without inducing internal axial loads. Since both the inner and outer rings of such bearing can be mounted with an interference fit, problems associated with a loose outer ring, such as fretting corrosion and distortion of the ring are avoided. The self-aligning bearing is established by a single row roller bearing with relatively long, barrel shaped rollers, whilst the inner and outer ring raceways are correspondingly concave and symmetrical. The bearing has been designed so that the rollers will always position themselves in the raceways for optimum load carrying performance.

Preferably, at each driving shaft one second bearing unit is configured as self-aligning axial bearing with two rows of barrel-shaped rollers with a common sphered raceway in an outer ring and two raceways inclined at an angle to a bearing axis in an inner ring to enable deflections or bending of the driving shaft in operation. For example, the second bearing unit may be a double row spherical roller bearing for locating the associated driving shaft axially in both directions. Thus, the second bearing unit is self-aligning and insensitive to misalignment of the driving shaft relative to the housing of the bearing unit, as well as to deflections or bending of the driving shaft in operation of the crusher.

Preferably, at each of the shaft openings are provided sealing units, e.g. slide ring seal- ings, for sealing the main housing to prevent water and cokes fines form leaking out of the housing. Additional sealing units, e.g. slide ring sealings, may be provided for sealing the bearing units to prevent water and coke fines from intruding into the bearings of the bearing units.

Due to the fact that the sealing function is separated from the bearing function the overall construction becomes more reliable. The bearing units are located outside the main housing and thus perfectly shielded from the abrasive and erosive material processed in the crusher. Thus, the bearing units can be optimized with respect to rotatable supporting the respective driving shaft. On the other hand, the sealing units are not subject to any bearing forces exerted by the respective driving shafts at all. Thus, the sealing units can be optimized for sealing the gap between the main housing and the respective rotating driving shaft in the respective shaft opening. For an automated control of the sealing units the respective slide ring seals may be configured to be loaded or biased with a predetermined gas or fluid pressure. By monitoring the pressure any leakage of one of the seals can immediately be detected by a corresponding pressure loss. Preferably, the seals of the sealing units are biased by compressed air the pressure of which is continuously monitored.

In one embodiment, each crushing roll has an axial length of preferably about 1500 mm (59.06 in) and an outer diameter of preferably about 1 330 mm (52.36 in) and an inner diameter of preferably about 1090 mm (42.91 in).

A further aspect of the invention relates to a delayed coking system comprising at least one coke crusher according to any one of above discussed embodiments and at least one coke drum having a bottom outlet coupleable to the upstream inlet of the coke crusher. The system may further comprise an unheading sliding valve by which the bottom outlet of the coke drum can be unheaded to open the coke drum to the inlet or the telescopic chute, if any, of the coke crusher.

Finally, the invention also concerns the use of a coke crusher according to any one of above discussed embodiments in a coke production unit, such as a delayed coker of a refinery or the like.

SHORT DESCRIPTION OF THE DRAWING FIGURES Objects and features of the invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appending claims only. It should be further understood that the drawings are merely inten- ded to conceptually illustrate the structures and the procedures described herein. For the illustration it is noted that the descriptive terms "left", "right", "bottom" and "top" refer to the illustrations with the references characters read in regular orientation. The invention is now described in more detail below with regard to the exemplary embodiments shown in the accompanying drawings, in which:

Fig. 1 shows a schematic diagram of a delayed coking system 2 with closed coke slurry, in which two coke crushers according to the invention are used;

Fig. 2 shows a cross-sectional side view of a coke crusher of the invention;

Fig. 3 shows another cross-sectional side view of the coke crusher of Fig. 2; shows enlarged views of details A and B of Fig. 3; Fig. 5 shows a side view of a crushing roll of the coke crusher of the invention;

Fig. 6 shows the cross-sectional view A-B of Fig. 5;

Fig. 7 shows the cross-sectional view C-D of Figs. 6;

Fig. 8a shows enlarged the view F of Fig. 7;

Fig. 8b is a view from above on the seizing tooth in Fig. 8a;

Fig. 9a shows enlarged the view G of Fig. 7; and

Fig. 9b is a view from above on the crushing tooth in Fig. 9a. DESCRIPTION OF EMBODIMENTS

Fig. 1 shows a schematic connection diagram of a delayed coking system 2 for production of petroleum coke, in the following herein called "pet coke" for short. Delayed coking is a thermal cracking process used in petroleum refineries to upgrade and convert petroleum residuum, i.e. bottoms from atmospheric and vacuum distillation of crude oil, into liquid and gas leaving behind pet coke. A furnace (not shown), e.g. a fired heater with tubes for passing through the petroleum residuum, is used to reach thermal cracking temperatures of about 485 to 505°C (905 to 941 °F). Since the petroleum residu- um stays only short time in the furnace, coking of the feed material is delayed until it reaches coke drums located downstream of the furnace. Basically, three physical structures of pet coke can be produced by delayed coking, namely shot, sponge, or needle coke. The respective physical structures and chemical properties of the pet coke determine the end use of the material. For instance, pet coke may be burned as fuel, calcined for use in the aluminum, chemical, or steel industries, or gasified to produce steam, electricity, or gas feedstock for the petrochemicals industry.

Now with reference to Fig. 1 , the exemplary delayed coking system 2 comprises two coke drums 4 and 8 forming a drum unit shown in the left hand part of Fig. 1 . The diamet- ers of the coke drums 4, 8 may range from 4 to 9 meters (1 3 to 30 ft) with the straight side being up to 40 m (1 31 ft) with top blind flange closure having a diameter of about 1 ,5 m (4.9 ft) and bottom blind flange having a diameter of about up to 2 m (6.6 ft) . In the bottom of the each coke drum also a respective inlet nozzle (not shown in Fig. 1 ) is attached for filling the coke drum during the delayed coking cycle.

The two coke drums 4 and 8 provide for a semi-batch mode operation of the system 2. That is to say, in the operating coke drum, heated petroleum residuum from the furnace (not shown) is injected into the bottom of the drum where the petroleum coke is going to solidify. In Fig. 1 , the left coke drum 4 is already filled with pet coke, i.e. the pet coke therein has solidified and formed a coke bed, and is gone offline, i.e. has been decoupled from the furnace. Then the coke drum 4 has been steamed, vented, and cooled prior to opening by a quenching cycle. Finally, both the top flange and the bottom are removed, i.e. un- headed, for the following coke drum decoking cycle.

After the drum is opened, as it is illustrated in Fig. 1 , in the decoking cycle the solidified pet coke is cut from the coke drum 4 using high pressure water ejected by means of a hydraulic coke cutting system comprising a coke cutting unit 58. Thereby, high pressure water (up to 300 bars / 4.350 psi) is used to cut the pet coke out of the coke drum 4. Usually derricks (not shown) are built on top of the coke drums 4, 8 so that a drill stem can be moved with a winch and cable into the drum. The high pressure water flows through a drilling hose to cutting unit 58 at the top of the drill stem. The drill stem is rotated, e.g. with an air motor at the top through a rotary joint. Down facing cutting nozzles are used for cutting a pilot hole into the coke bed all way down to the bottom outlet of the drum. Outward facing cutting nozzles are used for cutting the coke out of the coke drum 4 by spiraling downward at four to six RPM with vertical movement of one-half meter per revolution of the cutting unit 58. The coke cutting unit 58 may have both nozzles incorporated as a single drilling/cutting head.

In the cutting process, firstly, the pilot hole, having e.g. approximately one meter in diameter, is drilled from the top of the coke drum 4 to the bottom. Then, usually a vertical section of about four meter is cut by moving the cutting unit 58 up and down until the pet coke is all cut out of the section. Normally around 15 to 20 minutes are required to drill out the pilot hole and three to four hours to cut the whole coke bed.

Each of the two coke drums 4 and 8, respectively, is coupled with an associated coke crusher 6 and 10, respectively, installed underneath. The coke crushers 6, 10 are exemplary embodiments of the invention, i.e. the crushers are particularly adapted for crushing large coke chunks produced in the decoking cycle into coke pieces of a predetermined size.

The coke bed within the coke drum 4 is schematically depicted in Fig. 1 during ream out operation with the vertical pilot channel. Coke chunks collect at the bottom of the drum 4. Likewise, coke pieces flow through the slurry pipe 12 which are produced by the left coke crusher 6 by crushing and grinding the coke chunks into a predetermined maximum size. As a result, the coke slurry within the slurry pit 14 is a mixture of coke pieces having the predetermined size, smaller coke particles, and water.

The coke crushers 6 and 10 can be coupled to the respective coke drums 4 and 8 by an associated telescopic chute 7 and 9, respectively, being a transition element that can remotely be pulled up. When the coke crushers 6 and 10 are not coupled to the coke drums 4 and 8, the bottom of the coke drums 4 and 8 is closed. For said purpose, the telescopic chutes can be pulled back with respect to the bottom of the coke drums 4 and 8 thus do not connecting to the same. Alternatively, the respective upstream inlet of the coke crushers 4, 10 may be connected to a bottom outlet of the associated coke drum via an automated unheading unit, e.g. an automated slide valve. In such case, the respective coke crusher may also stay permanently coupled to the respective unheading unit associated thereto via the respective telescopic chute 7 and 9, respectively.

Telescopic chutes 7 and 9 may be configured such that they allow for automatic raising and lowering and for a secure remote docketing without bolting. In order to avoid that steam is released to the atmosphere, the chutes may comprise a steam tight construction.

The coke crushers 6 and 10 are mounted below the respective coke drums 4 and 8 such that coke chunks cut out of the coke bed get directly by effect of gravity into the upstream inlet of the respective coke crusher 6, 10. There the coke chunks are crushed into coke pieces of a predetermined maximum size of, according to one embodiment, preferably about 100 mm (4 in). Coke pieces of such size are suitable for further handling in further use thereof. Further, coke pieces of such size are suitable for being pumped as coke- water mixture which is also called coke slurry herein.

The coke crushers 6 and 10 are both exemplary embodiments of the invention, which are discussed in detail below in connection with Figs. 2 to 8. Basically, the coke crushers 6 and 10 provide for a rigid construction and are built of high abrasive-resistant materials. The coke crushers 6 and 10 have maximum pull-in ability by using two counter-wise rotating crushing rolls having large roll diameters and an optimized teeth pattern. The coke crushers 6 and 10 each comprise separate direct roll drives for each of its crushing rolls with high torque. Thereby, the coke crushers 6 and 10 have almost unlimited swallow ability for peak cutting loads. The coke crushers 6 and 10 are reversible and allow for a fully automated, self-controlling operation.

The outlets of the coke crushers 6 and 10 are both connected to a slurry pipe 12 that is formed as a closed, oblique pipe, and made from corrosion and abrasive resistant material. The coke slurry is transported - by effect of gravity and transport water - down through the slurry pipe 12 into a slurry pit 14 which is formed for example as a tight concrete pump pit.

In the middle of Fig. 1 , two dewatering bins 18 and 20 are shown, which similar to the pair of coke drums 4, 8 allow for batch mode operation. During decoking of the left coke drum 4, coke slurry is pumped from the slurry pit 14, particularly from a bottom portion thereof, via a slurry line 16 to the upper portion of the left dewatering bin 18. The coke pieces collecting in the dewatering bin 18 from bottom to top are schematically illustrated in Fig. 1.

In the illustration of the system in Fig. 1 , quench water lines and cooling lines are omitted for simplicity. Further parts of Fig. 1 are not relevant for the invention described herein so that for identification of parts not described herein in detail reference is made to the list of reference sign as well as to the applications incorporated by reference.

Now with respect to the Fig. 2 to 9, the special construction as well as the function of a roll crusher of the invention will be described. The roll crusher is adapted to be used as a coke crusher in a delay coking system such as discussed in connection with Fig. 1. The coke crusher is particular suitable for use in a delay coking system having a closed coke slurry system.

Fig. 2 shows a cross-sectional side view of a coke crusher 100 according to the invention in direction of the axes of rotation of the crushing rolls. Fig. 3 shows a further cross- sectional side view of the coke crusher of Fig. 2 perpendicular thereto.

Accordingly, the coke crusher 100 for crushing petroleum coke comprises a main housing 102, in which a pair of crushing rolls 104, 106 is arranged for rotation about respective parallel axes 108, 1 10. The crushing rolls 104, 106 have a predetermined diameter d (cf. Fig. 5) and a predetermined spacing W from each other there between. The predetermined spacing W, being the shortest distance between the surfaces 1 18, 120 of both crushing rolls 104, 106 defines a crushing window 1 12.

Each of the crushing rolls 104, 106 is basically cylindrical shaped and toothed by comprising on its surface 1 18 and 120, respectively, seizing teeth 1 14 and crushing teeth 1 16, which are described in more detail in connection with Figs. 5 to 9. Each of the teeth 1 14, 1 16 projects radially with respect to the respective axis of rotation 108, 1 10. The teeth 1 14, 1 16 have a maximum height of up to half of the predetermined spacing W. Further, the teeth 1 14, 1 16 are arranged in a predetermined tooth pattern (cf. also Figs. 5 to 7). By the special configuration of the teeth 1 14, 1 1 6 together with the special arrangement pattern thereof on the surfaces 1 18, 120 of the rolls 104, 106 the crusher 100 is able to nip and drag coke chunks into the crushing window 1 12 mainly by means of the seizing teeth 1 14 and to shatter and disintegrate the coke chunks by compression between the crushing rolls 104, 106 into coke pieces. In the compression both types of teeth cooperate.

The crushing rolls 104, 106 are driven in operation independently by individual hydraulic motors (not shown) so that a relative motion between the crushing rolls 104, 106 can be controlled by different rotational speeds of the respective crushing roll 104, 106. Further, the crushing rolls 104, 106 are rotated in opposite directions 122, 124, i.e. are counter-wise rotated. As mentioned above, it has been found that particular in the situation of crushing soft types of coke chunks, running the crushing rolls at different rotations per minute provides for an increased through put.

An upstream inlet 126 of the main housing 102 comprises a, preferably circular, input opening 128 for receiving the coke chunks cut out from the coke drum 4. The input opening 128 is adapted to direct the coke chunks onto the crushing rolls 104, 106. Further, the input opening 128 has a diameter D that corresponds roughly with the length of the crushing rolls 104, 106.

Furthermore, the input opening 128 has a center 1 30 that is located straight above of the crushing window 1 12, more precisely, preferably above the geometric center of the crushing window 1 12.

As illustrated in the left bottom corner portion of Fig. 1 , the crusher 6, which may be a crusher 100 as described in connection with Figs. 2 to 9, further comprises a chute 7 for coupling the upstream inlet 126 of the crusher 6 to a bottom outlet 1 1 of the coke drum 4. The chute 7 has an inner diameter corresponding to the diameter D of the input opening 128 of the crusher 100. Further, the chute 7 comprises an input aperture 1 3, wherein a ratio of the input diameter of the Input aperture 1 3 to the predetermined spacing W of the crushing rolls 104, 106 is adapted to the crushing ratio of the crusher 100. That is to say, the crusher 100 is configured to have a predetermined crushing ratio that is defined by the maximum coke chunk size that can be nipped and dragged by the crusher 100 into the crushing window 1 12 divided by the predetermined spacing W, For better distinguishabil- ity, it is referred to the chute 9 coupling the right crusher 10 in Fig. 1 with the right coke drum 8. The chute 9 also comprises the discussed input aperture 1 3.

As explained in the summary of the invention, by means of the input aperture 1 3 it can be secured that the crushing rolls 104, 106 are charged only with coke chunks of a maximum size, which still can be nipped and dragged in by the crusher 100. In one embodiment of the crusher a crushing ratio is achieved of 10 to 1 , i.e. the input aperture 1 3 has a diameter that is ten times larger as the predetermined spacing W of the crushing rolls 104, 106. Thus, by only feeding chunks of pet coke that are up to 10 times bigger as the predetermined crushing window 1 12 to the crusher 100, the crusher 100 can be reliable operated continuously without getting blocked.

If one or more coke chunks having a size greater as the predetermined maximum input size are produced during decoking of the coke drum 4, such coke chunks will be withhold at the input aperture 1 3. Thus, the on-going crushing operation of the crusher 100 will clear the inner space of the chute 7 so that the coke chunk(s) withheld at or in the input aperture 1 3 can be cut by means of the coke cutting means 58 used in the coke cutting process for decoking the coke drum.

Each of the crushing rolls 104, 106 comprises an axial through boring with respective left and right axial bushings for receiving a respective driving shaft that is coupleable to a respective driving means. Fig. 4 shows enlarged views of details of Fig. 3 marked by A and B, respectively. It is noted that in Figs. 3 an axial cross-section of the left crushing roll 104 and in Fig. 4 details A and B thereof are shown. Thus, left crushing rolls 104 comprises an axial through boring 1 32 with a left axial bushing 1 34 and right axial bushing 1 36 for re- ceiving its associated driving shaft 1 38 that is coupleable to a driving means (not shown) via a drive coupling unit 140.

In a particular embodiment, each of the crushing rolls 104, 106 has an axial length of about 1500 mm (59.06 in), an outer diameter of about 1 330 mm (52.36 in), and an inner diameter of about 1090 mm (42.91 in).

Figs. 3 and 4 illustrate exemplary by means of the axial cross-section of the left driving shaft 1 38 how the crushing rolls 104, 106 are installed in the main housing 102 of the crusher 100. It goes without saying, that the following description is valid for the installation of the right driving shaft, correspondingly.

Accordingly, the main housing comprises respective shaft openings 142, 144 for passing through respective ends 1 6, 148 of the left driving shaft 1 38. Further, the main housing 102 is provided with respective console structures 164, 166 just below the respective shaft opening on which respective bearing units 150, 152 are mounted outside the main housing 102 adjacent to the respective shaft openings 142, 144 so that the bearing units 150, 152 can receive a respective one of the ends of the left driving shaft 1 38.

By this construction, the driving shaft 1 38 is removable installed. For installation, the driving shaft 1 38 is inserted, for example, from the left side of the main housing 102 through the left one as a first one of the shaft openings 142, next through the axial trough boring 1 32 of the crushing roll 104, and finally through the right one as a second one of the shaft openings 144. Then, on each side of the main housing 102 sealing units 160, 162 are installed at each of the shaft openings 142, 144 for sealing space between the main housing 102 and the driving shaft 1 38. For rotatable supporting the driving shaft 1 38 at each of its ends 146, 148 a left bearing unit 150 and a right bearing unit 152 is installed on the console structure 164 and 166, respectively, below the shaft opening 142 and 144, respectively. As discussed above, this arrangement advantageously allows for separating the sealing function and the bearing function.

The left bearing unit 150 of the driving shaft 138 is configured as a self-aligning radial bearing. For that purpose, the bearing of the bearing unit 150 comprises an inner ring 154 that is configured so as to move independently of an outer ring 156 of the bearing.

Between the inner ring 154 and the outer ring 156 there are provided barrel shaped rollers 158, which can move in correspondingly shaped raceways in the rings 154, 156, i.e. the raceways of the inner ring 154 and the outer ring 156 are correspondingly concave and symmetrical to receive the barrel shaped rollers 158. As a result, the driving shaft 138 is enabled to move in the bearing unit 150 smoothly without inducing internal axial loads.

The right bearing unit 152 of the driving shaft 1 38 is configured as self-aligning axial bearing. In detail, the bearing unit 152 is arranged as a double row spherical roller bearing comprising two rows of barrel-shaped rollers 159 with a common sphered raceway in an outer ring 157 and two raceways inclined at an angle to the driving shaft 1 38, corresponding to the bearing axis, located in an inner ring 155 so that the driving shaft 1 38 may be deflected or bend in operation of the crusher 100.

The right end 148 of the driving shaft 1 38 is passed through the right bearing unit 152 for coupling to an associated driving means (not shown) by means of the drive coupling 140. Preferably, the driving means is a hydraulic motor which is able to provide high torque, on the one hand, and is able to absorb sudden and high impulse stress caused by the greatly varying loads produced by the coke chunks fed into the crusher 100.

Fig. 5 shows a side view of the left crushing roll 104 of the coke crusher 100 as illustrated in Fig. 2 to 4. Fig. 6 shows a corresponding cross-sectional view of the crushing roll 104 of Fig. 5.

The crushing roll 104 shown in Figs. 5 and 6 is casted integrally with the seizing teeth 1 14 and crushing teeth 1 16 in one pour. This is possible due to the special configured teeth 1 14, 1 16, which are highly wear resistant and thus, need not to be exchangeable.

Further, the crushing roll 104 is casted from cast iron with a hollow drum-like shape in one pour; basically, there may be applications in which the rolls also may be casted solidly in one pour. The crushing roll 104 comprises respective axial abutting faces 1 72 and 1 4 (cf. Fig. 6), one face 1 72 thereof is illustrated in Fig. 5.

Moreover, Figs. 5 and 6 show the axial through boring 1 32 with respective axial bushings 1 34, 136 at each of the abutting faces 1 72, 1 74 and extending into the interior 1 76 of the drum-shaped roll 104. As discussed in connection with Figs. 2 to 4 the axial through boring 1 32 is provided for receiving the associated driving shaft 1 38.

There is provided a form-locking or positive locking joint between the driving shaft 1 38 and the crushing roll 104 so as high torque from the driving means may be transferred via the driving shaft 1 38 to the crushing roll 104. In detail, the bushings 1 34, 1 36 are provided with respective clamping collars which allow an easy separation of the driving shaft 1 38 from the crushing roll 104; e.g. the driving shaft may be disassembled from the crushing roll 104 for repair or replacement.

As afore-mentioned, the sizing teeth 1 14 and the crushing teeth 1 16 are both integral elements of the crushing rolls 104, 106 and are arranged alternately and regular spaced on parallel circumferential lines 1 70 running perpendicular to the respective axis 108 of rotation of the crushing roll 104. As depicted in Fig. 5, the seizing teeth 1 14 are regularly spaced by an angle of 18 degrees as illustrated by way of example between seizing teeth 1 14a, 1 14b. Same way, the crushing teeth 1 16 are regularly spaced by an angle of 18 degrees as illustrated by way of example between crushing teeth 1 16a, 1 16b. Further, the seizing teeth 1 14 and the crushing teeth 1 16, respectively, are arranged alternately, aligned and regular spaced in axial direction of the crushing roll 104. Thus, each crushing roll comprises axial rows comprised of alternating crushing teeth 1 16 and seizing teeth 1 14. This alternating arrangement of the teeth axial direction also provides for a further reduction of the amount of produced coke fines. In other words, the crushing roll 104 comprises axial rows of teeth of both types in an alternating sequence. Thereby, the seizing teeth 1 14 and the crushing teeth 1 16, respectively, are part of a V-shaped tooth formation where the tip of the "V" is pointing into the direction of rotation of the crusher roll 104. The V-shaped tooth formation provides the crusher 100 with improved drag-in ability.

A further aspect of the crusher 100 relates to the two types of special configured teeth, namely the seizing teeth 1 14 and the crushing teeth 1 14, as well as the particular arrangement of the teeth on the respective crushing roll, i.e. the tooth pattern. Fig. 7 shows the cross-sectional view C-D as a detail of the crushing roll 104 and marked in Fig. 6. Figs. 8a, 8b and 9a, 9b show respective enlarged views F and G, respectively, of a seizing tooth 1 14 and a crushing tooth 1 16, respectively, of the crushing roll 104 as marked in Fig. 7.

As particularly illustrated in Fig. 7 together with Figs. 8a and 8b, from a functional point of view, a seizing tooth 1 14 comprises a shovel blade-like operating portion 231 that is directed into the respective direction of rotation 182. The shovel blade-like operating portion 231 is tilted into the respective direction of rotation of the respective crushing roll 104. By this construction, the seizing teeth 1 14 are able to cut into coke chunks and to exert high force on the coke chunks to convey them into the crushing window 1 12.

Further, the seizing tooth 1 14 further comprises a tip 214 that forms the most extending part of the seizing tooth 1 14 with respect to the surface 1 18 of the crushing roll 104 and a leading point 21 1 of the seizing tooth 1 14 with respect to the respective direction of rotation 182.

Furthermore, the seizing tooth 1 14 is configured with compression surfaces 215a, 215b, 215c running from the tip 214 with a decreasing distance to the respective surface 1 18 of the crushing roll 104. As illustrated in Figs. 7 and 8b, the compression surfaces 215a, 215b, 215c are beveled with respect to the respective surface 1 18 of the respective crushing roll 104. Moreover, a rear compression surface 215b is a trailing surface with respect to the direction of rotation 182 and is oriented basically parallel to the respective axis of rotation 108 (cf. Fig. 2). The other two compression surfaces 215a, 215b form with respect to the axial direction of the respective crushing roll 104 a left and a right compression surface, that respectively run transversely to the respective axis of rotation 108 (cf. Fig. 2).

Due to this certain configuration, the seizing teeth 1 14 have found to be highly resistive against wear, it is assumed that by the provision of the compression surfaces 215a, 215b, 215c, sharp cutting edges are avoided at the seizing teeth 1 14 which are most likely subject to wear in continuous operation. The seizing teeth 1 14 of the invention are configured to be dull-edged and to exert mainly compression to coke chunks once moved into the crushing window 1 12 (cf. Fig. 2).

In more detail, each of the seizing teeth 1 14 is comprised of a truncated first conic solid 210 as main body with a first oblique axis 212 and a second conic solid 216 with a second oblique axis 218 as tip of the seizing tooth 1 14. The first oblique axis 212 and the second oblique axis 218 are both tilted into the rotational direction 182 of the crushing roll 104.

In the certain embodiments, the base or food print of the seizing teeth 1 14 has a polygon shape with corners and edges. In the embodiment shown in the figures, each seizing tooth 1 14 comprises a rectangular base 220 with four edges 222a, 222b, 222c, 222d. With respect to the arrangement of the seizing teeth 1 14 on the crushing roll 104, a left edge 222a and a right edge 222b (cf. Fig. 8b) are located in parallel to a circumferential line 188 of the crushing roll 104 and perpendicular to the axis 108 of rotation of the crush - ing roll 104. In the illustrated particular embodiment, the base 220 of the truncated first conic solid

210 is rectangular shaped and comprises two longitudinal edges 222a and 222b parallel to the circumferential line 188. The two longitudinal edges 222a and 222b have an equal length of about 60 mm (2.36 in). Further, there are two cross-edges 222c and 222d having an equal length of about 50 mm (1.97 in).

A tip base 224 of the second conic solid 218 being the interface to the truncated first conic solid 212 is also rectangular with two longitudinal edges 226a and 226b. In the illustrated particular embodiment, the two longitudinal edges 226a and 226b have an equal length of about 25 mm (0.98 in). Further, there are two cross-edges, a leading cross-edge 226c and a trailing cross-edge 226d. In the illustrated particular embodiment, the leading cross-edge 226c and the trailing cross-edge 226d have an equal length of about 40 mm (1.57 in).

All seizing teeth 1 14 of each crushing roll 104, 106 comprise a same equal total height 228. In the illustrated particular embodiment, the total height 228 is about 60 mm (2.36 in), of which the truncated first conic solid 212 has a height of about 50 mm

(1 .97 in) and the second conic solid 21 8 has a height 230 of about 10 mm (0.39 in) extending from the interface with the truncated first conic solid 212.

A particular feature of the seizing teeth 214 enables the crushing roll 104 to grasp coke chunks and to feed the chunks into the crushing window both the truncated first conic solid 212 and the second conic solid 218 provide for respective leading surfaces, namely main body leading surface 232 and a tip leading surface 234 that are oriented, i.e. are facing, and tilted into the rotational direction 182 of the crushing roll 104. Both leading sur- faces 232, 234 form a common plane 236 that functions as the shovel blade-like operation portion 231 .

As particularly illustrated in Fig. 7 together with Figs. 9a and 9b, from a functional point of view, each of the crushing teeth 1 16 comprises a wedge-like operating portion 281 that is directed into the respective direction of rotation 1 82 of the crushing roll 104. The crushing tooth 1 16 further has a tip 201 that forms the most extending part of the crushing tooth 1 16 with respect to the respective surface 1 18 of the crushing roll 104. In more detail, any one of the crushing teeth 1 16 has basically the shape of a conic solid with an oblique axis 180 tilted into the rotational direction 182 of crushing roll 104. In the certain embodiments, the base or food print of the crushing teeth 1 16 has a polygon shape with corners and edges. In the embodiment shown in the figures, each crushing tooth 1 16 comprises a quadratic base 1 84 with four corners 186a, 186b, 1 86c, and 186d resulting in a pyramidal shape. In other words, each crushing tooth 1 16 is a pyramid with a quadratic shaped food print (base 184).

With respect to the arrangement of the pyramidal shaped crushing teeth 1 16, two corners 186a, 186b of the base 184 are located on a circumferential line 188 of the crush- ing roll 104, which is running traversal to the axis 108 of rotation of the crushing rolls 104, 106. Thus, each crushing tooth 1 16 has a leading edge 200 that is directed into the direction of rotation 182 and runs from the leading corner 186b up to the apex 202 of the crushing tooth 1 16. In the illustrated particular embodiment, the quadratic base 184 of the conic solid comprises four edges 190a, 1 0b, 190c, and 190d with a length of about 40 mm

(1 .57 in). In each pair of opposite ones of the four corners, i.e. leading corner 1 86b and tri- aling corner 186a as well as left corner 186c and right corner 1 86d, are spaced by a distance of about 50 mm (1 .97 in). As mentioned above, each crushing tooth 1 1 6 has an ob- lique axis 1 80 that is tilted so that the apex 200 of each crushing tooth 1 16 is shifted by a predetermined amount 1 8 into the direction of rotation 182. The base point 192 of the oblique axis 182 and the base point 194 of the height 196 of the conic solid preferably have a distance of about 5 mm (0.20 in) corresponding to that predetermined amount 1 98. Furthermore, all crushing teeth 1 1 6 comprise an equal height 196 of about 35 mm (1 .38 in).

In the particular embodiment illustrated in Figs. 5 to 9b, each crushing roll 104 comprises preferably nine circumferential lines 1 88 and on each of the circumferential lines 188 twenty seizing teeth 1 14 and twenty crushing teeth 1 16.

Preferably, transition surfaces 238 between the teeth 1 14, 1 1 6 and the surface of the crushing roll 104 have a common transition radius, preferably of 10 mm (0.39 in). Now with reference to Figs. 2 and 3, the integration of the coke crusher 100 in a delayed coking system as sketched in Fig. 1 is shortly described.

Accordingly, the coke crusher 100 as described in detail above in connection with Figs. 2 to 9b can be installed adjacent, i.e. underneath an associated coke drum 4 having a bottom outlet that can be coupled to the upstream inlet 128 of the coke crusher 100.

The coking system 2 may be provided with an unheading sliding valve by which the bottom outlet of the coke drum 4 can be unheaded to open the coke drum 4 to the upstream inlet 128 of the coke crusher 100, i.e. to the telescopic chute 7 of the coke crusher 100.

As explained in connection with Fig. 1 , for further handling of the pet coke pieces of a maximum seize produced by the combination of the coke drum 4 and the coke crusher 100, the pet coke pieces are supplied into the slurry pipe 12. In the slurry pipe 12 the pet coke slurry is preferably transferred by means of effect of gravity into the slurry pit 14. To this effect, the coke crusher 100 is preferably installed at an elevated position in the delayed coking system 2.

As shown in Figs. 2 and 3, the main housing 102 of the coke crusher 100 is open downward to the bottom. This is particular advantageous since the crushing rolls 104 and 106 may rotate freely in the bottom part of the main housing 102 thereby jamming of the crusher 100 is unlikely.

For supplying the produced coke pieces to the slurry pipe 12 (cf. Fig. 1 ) the coke crusher 100 is set up on a support frame 250 that has an rectangular opening 252 located just underneath the main housing 102 and matching nearly the cross-section area of the main housing 102. The opening 252 has two edges 254a, 254b that run parallel to the crushing rolls 104, 106 and that are hopper-like tapered or chamfered. The other edges 255a, 255b of the opening 252 are running just straight to the bottom. Thus, the opening 252 corresponds to the crusher outlet 256.

The crusher outlet 256 is coupled with a hopper 260 having a circle-shaped outlet flange 262 for connecting with the slurry pipe 12. Thus, the hopper 260 serves as an interface for coupling the coke crusher 100 with the slurry pipe 12 transforming the shape of the rectangular crusher outlet 256 into a circular form.

To achieve the elevated location, the hopper 260 is mounted into an through hole 272 of a console construction 270. The console construction 270 may be made of concrete and be a part of a refinery facility. The support frame 250 of the coke crusher 100 is mounted on the console construction 270 so that the crusher outlet 256 fits/connects to the hopper inlet 264. Summarizing, it has been presented an improved coke crusher 100 for crushing petroleum coke. The crusher 100 has a main housing 102 and a pair of crushing rolls 104, 106 arranged in said main housing 102 for rotation about parallel axes 108, 1 10, said crushing rolls 104, 106 having a predetermined diameter d and a predetermined spacing W there between from each other defining a crushing window 1 12. Each of said crushing rolls 104, 106 being cylindrical shaped and toothed comprising on its surface 1 1 8, 120 seizing teeth 1 14 and crushing teeth 1 16.

As to the achieved improvements, the coke crusher 100 of the present invention has shown to be highly reliable, i.e. during the process of cutting solidified coke out of a coke drum large petroleum coke chunks cannot jam or block the coke crusher 100. Further, the coke crusher 100 achieves a high pull-in ability to nip and drag in large coke chunks without getting blocked. Furthermore, during cutting out of the solidified coke from the coke drum, the coke crusher 100 is able to process high peak loads by providing for almost unlimited swallow ability. Moreover, the coke crusher 100 allows for continuous loading during decoking so that the coupled coke drum can be cleared without delay. Last but not least, it has been found that the coke crusher 100 produces significantly less coke fines as expected from the experience with available crushers in the field.

It is assumed that the improvements are particular achieved by the design of the crusher rolls 104, 106. Thus, teeth on the crusher rolls 104, 106 are arranged in a predetermined tooth pattern or formation and project radially with a maximum height of up to half of the predetermined spacing W such that the crusher 100 is operateable to nip and drag coke chunks into said crushing window 1 12 by means of said seizing teeth 1 14 and to disintegrate the coke chunks primarily between said crushing rolls 104, 106 by splitting and cleaving into coke pieces of a predetermined maximum size. To that effect, the seizing teeth 1 14 and crushing teeth 1 16 respectively comprise a tip configuration with beveled compression surfaces providing for a wedge effect so that coke chunks are disintegrated in the crushing window 1 12 primarily by splitting or cleaving.

Finally, the coke crusher 100 is particular useful in a refinery as maintenance time can be reduced by avoiding tooth replacement or the like, i.e. the coke crusher 100 has nearly an unlimited lifespan. A particular field of use for the crusher 100 is in a delayed coking system 2 that comprises at least such a coke crusher 100 and an associated coke drum 4 having a bottom outlet that is coupleable to the upstream inlet 1 28 of the coke crusher 100 for feeding coke chunks thereto. REFERENCE SIGNS AS USED IN THE DRAWINGS

2 petroleum coke handling system

4 left coke drum

6 left coke crusher

7 left chute

8 right coke drum

9 right chute

10 right coke crusher

1 1 coke drum bottom outlet

12 slurry pipe

1 3 input aperture

14 slurry pit

16 slurry line

18 left dewatering bin

20 right dewatering bin

22 drain water line

24 drain water pit

26 drain water line

28 water settling tank

29 clean water tank

30 cold quench water line

32 cooling water line

34 hot quench water line

36 vapor discharging line

38 vent

40 overflow line

42 safety valve

44 overflow line to slurry pit

46 overflow line to water settling tank

48 line to clean water tank

50 balancing line

52 conveyor belt

54 line to slurry pit

55 transport water line

56 transport water line

58 coke cutting unit

100 coke crusher

102 main housing

104 left crushing roll

106 right crushing roll

108 left axis of rotation

1 10 right axis of rotation 1 12 crushing window

1 14 seizing tooth

1 16 crushing tooth

1 18 surface of left crushing roll

120 surface of right crushing roll

122 direction of rotation of left roll

124 direction of rotation of right roll

126 upstream inlet of crusher

128 input opening of crusher inlet

1 30 center of crusher input opening

1 32 axial through boring

1 34 left axial bushing

1 36 right axial bushing

1 38 driving shaft

140 drive coupling unit

142 left shaft opening

144 right shaft opening

146 left end of left driving shaft

148 right end of left driving shaft

150 left bearing unit

152 right bearing unit

154 inner ring of left bearing unit

156 outer ring of left bearing unit

158 barrel shaped rollers

160 left sealing unit

162 right sealing unit

164 left console structure

166 right console structure

1 70 circumferential line

1 72 abutting face of left crushing roll

1 74 abutting face of left crushing roll

1 76 interior of crushing roll

1 80 oblique axis of crushing tooth

181 wedge-like operating portion of crushing tooth

1 82 direction of rotation

184 quadratic base of crushing tooth

186a, b, c, d corners of quadratic base of crushing tooth

1 88 circumferential line

1 0a, b, c, d edges of quadratic base

1 92 base point of oblique axis

194 base point of height

196 crushing tooth height

1 98 distance between base point and height 200 leading edge of crushing tooth

201 tip of crushing tooth

202 apex of crushing tooth

204 trailing edge of crushing tooth

210 truncated first conic solid of seizing tooth

21 1 leading point of seizing tooth

212 first oblique axis of seizing tooth

214 tip of seizing tooth

215a, b, c compression surfaces of seizing tooth

216 second conic solid of seizing tooth

218 second oblique axis of seizing tooth

220 rectangular base of seizing tooth

222a, b, c, d edges of base of seizing tooth

224 tip base of seizing tooth

226a, b longitudinal edges of tip base of seizing tooth

226c, d cross-edges of tip base of seizing tooth

228 total height of seizing tooth

230 height of second conic solid of seizing tooth

231 shovel blade-like operating portion of seizing tooth

232 leading surface of truncated first conic solid of seizing tooth

234 leading surface of second conic solid of seizing tooth

236 common plane formed by leading surfaces of seizing tooth

238 transition surface

250 support frame

252 rectangular opening in support frame

254a, b axial edges of opening in support frame

255a, b straight edges of opening in support frame

256 crusher outlet

260 hopper

262 outlet flange of hopper d diameter of crushing roll

W spacing between crushing rolls

D diameter of input opening

L axial length of crushing roll(s)

* * *