DESC:FIELD
The present disclosure relates to a decanter system, particularly, to a down-comer arrangement for a decanter system.
DEFINITION(S)
‘Supernatant’ - the clear fluid above a sediment or precipitate settled at the bottom of a reservoir of a gravity based decanter system
BACKGROUND
A decanter system is used in various applications such as phase separation in case of chemical reactors wherein settled down precipitates are required to be separated. The decanter systems are also used in waste water treatment or biological reactors wherein settled down sediments or sludge are required to be separated. The decanter system is used for the separation of liquids in a mixture of liquids having different densities or for phase separation, wherein a top layer of liquid referred to as supernatant from which a precipitate or sediment has settled is removed from a reservoir. The decanter system for wastewater systems, may be a fixed type decanter or a floating type decanter. The decanter system is mounted in a reservoir that holds a mixture of liquids having different densities, and generally includes a tray, a scum entry prevention mechanism or a scum barrier, a down-comer, and an outlet of the reservoir.
The precipitate in case of a chemical liquid reaction mixture or sludge in case of waste water, settles down at the bottom of the reservoir and the supernatant at the top that is free from scum and precipitates seeps into the tray through the scum entry prevention mechanism. More specifically, the tray floats up and down with the changing liquid levels in the reservoir. The scum entry prevention mechanism or the scum barrier generally includes a valve or a flap functionally coupled to the tray and restrains suspended solids such as surface scum, floating debris, and foam from entering the tray of the decanter system, i.e., the main function of the scum entry prevention mechanism is to ensure that scum free supernatant or clear supernatant enters into the tray of the decanter system. In case of conventional scum entry prevention mechanisms, the gap between the flap and the opening configured on the tray, decides the amount of scum entering into the tray which is proportional to the area of opening left uncovered by the flap. The scum mostly contains foam resulting from bubbling / turbulence and other light particles carried with the liquid.
The down-comer is a tubular arrangement having a plurality of connecting pipes that forms fluid communication between the tray and outlet of the reservoir, thereby facilitating evacuation of the clear supernatant received in the tray from the reservoir via the outlet of the reservoir. More specifically, a manual/automated valve is in fluid communication with the tubular arrangement of the down-comer and facilitates evacuation of the clear supernatant from the reservoir. The down-comer is in fluid communication with the tray and receives clear supernatant from the tray, an operative bottom header is in fluid communication with the down-comer and facilitates the discharge of the clear supernatant therethrough. The connecting pipes are generally straight pipes and transfer the clear supernatant collected in the tray to the bottom header, thereby evacuating the clear supernatant from the reservoir. In case floatables such as surface scum, floating debris and foam carried with the supernatant reaches the tubular elements of the down-comer, it may block the interior of the tubular elements of the down-comer, thereby requiring cleaning, maintenance, and interrupted operations of the decanter system. Such interruptions in the operations of the decanter system are undesirable. Further, such blocking of the tubular elements of the down-comer may result in frequent maintenance thereof. In order to prevent the scum from entering the tray and ultimately entering the tubular elements of the down-comer, the scum entry prevention mechanism is provided. Generally, the scum entry prevention mechanism includes a flap that is adapted to close an opening formed on the tray, thereby preventing floatable such as surface scum, floating debris and foam from entering the tray.
In case of the conventionally known tubular arrangement for the down-comer, the tubular elements connecting the tray to the outlet of the reservoir are generally straight pipes that are inclined at an angle in the range of 16-45 degree with respect to the vertical walls of the reservoir, as such a slanted configuration of the connecting pipes assist the flow through the connecting pipes. However, the conventionally known tubular arrangement for the down-comer has various limitations, for example, the conventional down-comers do not function effectively in case the angle inclination of the connecting pipes is less than 20 degrees with respect to the vertical wall of the reservoir, more specifically, in case of conventional down-comers, back pressure is observed in the bottom section of the connecting pipes, also referred to as the arm pipes. Further, in case of the conventional down-comers, the arm pipes are over–sized and bulky, and the arm pipes and the down-comer pipes are most of the time in full flow condition, where the free drain is not observed in the bottom header. Further, the flow though the tubular connecting pipes is not smooth in case of conventionally known down-comers, and the discharge of the clear supernatant collected in the tray via the connecting pipes and the outlet of the reservoir may not be at a uniform rate. Further, in case of conventionally known tubular arrangement for the down-comer, free drain is not observed in the operative bottom header.
In order to overcome the above limitations of the conventionally known tubular arrangement for the down-comer, there is a need to alter the configuration of the tubular arrangement for the down-comer for a decanter system. More particularly, there is a need for a down-comer arrangement having a configuration that eliminates the chances of flow separation, back pressure, and frequent blocking of the tubular connecting pipes of the down-comer and drawbacks associated there-with. Further, there is a need for a tubular arrangement for down-comer that is having a compact configuration. Still further, there is a need for a tubular arrangement for a down-comer that is having such a configuration that back pressure in the bottom section of the connecting pipes is eliminated. Furthermore, there is a need for a tubular arrangement for down-comer that prevents separation of flow through the connecting pipes of the down-comer. Still further, there is a need for a tubular arrangement for a down-comer that is having a configuration such that the flow of the clear supernatant through the connecting pipes is assisted by the configuration of the connecting pipes under gravity. Still further, there is a need for a tubular arrangement for a down-comer that is having a configuration that assists in quick evacuation of the clear supernatant from the reservoir. Furthermore, there is a need for a tubular arrangement for a down-comer that is having a configuration that achieves the desired draining water velocities and draining water flow within desired decanting time.
SUMMARY
The present disclosure discloses a decanter system having a tubular arrangement for down-comer for drawing supernatant from a reservoir at uniform flow rate. The tubular arrangement for the down-comer comprises a tray configured to receive the supernatant from the reservoir. At least one bottom header is configured to receive the supernatant from the tray and discharge it therefrom. The arrangement further comprises a plurality of connecting pipes that is configured to transfer the supernatant from the tray to the bottom headers. The plurality of connecting pipes further comprises a plurality of straight connecting pipes extending from the tray in an operative vertically downward direction, wherein an operative top end of the plurality of straight connecting pipes is in fluid communication with the tray and an operative bottom end thereof is in fluid communication with one of the bottom headers. The plurality of connecting pipes further comprises a plurality of bent connecting pipes extending in an operative downward direction from the tray and terminating in an operative end of the bottom header. The plurality of bent connecting pipes is in fluid communication with the tray and the bottom headers. The plurality of bent connecting pipes have a straight portion, a first bent portion extending from the straight portion at a pre-determined angle with respect to said straight portion, and a second bent portion extending from the first bent portion to be terminated in the bottom header.
OBJECTS
Some of the objects of the present disclosure which at least one embodiment is adapted to provide, are described herein below:
It is an object of the system of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
An object of the present disclosure is to provide a tubular arrangement for down-comer that is having compact configuration.
Another object of the present disclosure is to provide a tubular arrangement for down-comer that is having such a configuration that back pressure in the bottom section of the connecting pipes eliminated due to partially full flow conditions even in the lowest angle of dcantation.
Still another object of the present disclosure is to provide a tubular arrangement for down-comer that is having such a configuration that operates effectively irrespective of lower angle of inclination of the connecting pipes.
Yet another object of the present invention is to provide a tubular arrangement for down-comer for a decanter system that achieves uniform, smooth flow through the tubular elements of the tubular arrangement for down-comer.
Another object of the present disclosure is to provide a tubular arrangement for down-comer for a decanter system that achieves optimized arm pipe and bottom header size, thereby resulting in material saving.
Still another object of the present disclosure is to provide a tubular arrangement for down-comer for a decanter system that achieves shortest draining path for supernatant flow, minimal arm and header pipe length, thereby minimizes the friction losses faced by the supernatant flow through the draining path.
Again, an object of the present disclosure is to provide a tubular arrangement for down-comer that prevents separation of flow through the connecting pipes of the down-comer.
Another object of the present disclosure is to provide a tubular arrangement for down-comer that is simple in construction.
Another object of the present disclosure is to provide a tubular arrangement for down-comer for a decanter system that is having such a configuration that tray overflow is prevented.
Still another object of the present disclosure is to provide a tubular arrangement for a down-comer for a decanter system that is reliable and cost effective.
Further object of the present disclosure is to provide a tubular arrangement for down-comer that allows the flow there-through to be free flowing under gravity.
Again, an object of the present disclosure is to provide a tubular arrangement for down-comer that is efficient in evacuating the clear supernatant from the reservoir.
Another object of the present disclosure is to provide a tubular arrangement for a down-comer having such a configuration that kinetic energy of arm pipe flow is utilized to aid bottom header drainage.
Yet another object of the present disclosure is to provide a tubular arrangement for down-comer that facilitates quick evacuation the clear supernatant from the reservoir at a uniform rate.
Other objects and advantages of the present disclosure will be apparent from the following description when read in conjunction with the accompanying figures, which are not intended to limit the scope of the present disclosure.
Another object of the present disclosure is to provide a tubular arrangement for optimized bottom header length and thus reduce the material loading on the bottom header
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
A tubular arrangement for a decanter system for supernatant evacuation of the present disclosure will now be explained in relation to the non-limiting accompanying drawings, in which:
Figure 1 illustrates a schematic representation of a conventional tubular arrangement for a down-comer for a decanter system, wherein straight and parallel tubular connecting pipes connect a tray of the down-comer to a bottom header that directs clear supernatant collected in the tray to an outlet of the reservoir;
Figure 2a illustrates a front view of the conventional tubular arrangement of Figure 1;
Figure 2b illustrates a side view of the conventional tubular arrangement of Figure 1;
Figure 2c illustrates the plan of the conventional tray arrangement of Figure 1;
Figure 2d illustrates side view of the conventional tray arrangement of Figure 1;
Figure 3 illustrates a front view of a tubular arrangement for a down-comer for a decanter system in accordance with an embodiment of the present disclosure, wherein outwardly disposed tubular elements are straight and parallel to each other while inwardly disposed tubular elements are diverging outwardly;
Figure 4 illustrates a front view of the tubular arrangement of Figure 3;
Figure 5 illustrates a rear view of the tubular arrangement of Figure 3;
Figure 6a illustrates a left hand side view of the tubular arrangement of Figure 3;
Figure 6b illustrates a left hand side view of the tubular arrangement of Figure 3 with an enlarged view depicting tray orientation with respect to the connecting pipes;
Figure 7 illustrates a right hand side view of the tubular arrangement of Figure 3;
Figure 8 illustrates a top view of the tubular arrangement of Figure 3;
Figure 9 illustrates a bottom view of the tubular arrangement of Figure 3;
Figure 10 illustrates an isometric view of the tubular arrangement of Figure 3;
Figure 11 illustrates a side view of decanter system comprising the tray, the tubular arrangement of the down-comer and the bottom header, wherein the decanter system is in lowermost position making an angle of 5 degrees;
Figure 12 illustrates a front view of the tubular arrangement in another configuration illustrating the extended tray configuration;
Figure 13 illustrates a front view of the tubular arrangement in accordance with another embodiment, wherein adjacent tubular elements are connected to each other by additional tubular arm elements;
Figure 14a illustrates a schematic representation depicting water distribution in a 3-d simulation model of a conventional tubular arrangement for a down-comer for a decanter system in accordance with the prior art under pre-determined set of simulation conditions or boundary conditions;
Figure 14b illustrates a schematic representation depicting velocity profile on a central plane of a 3-d simulation model of the tubular arrangement of Figure 14a;
Figure 14c illustrates a schematic representation depicting pressure contours on central planes of a 3-d simulation model of the tubular arrangement of Figure 14a;
Figure 14d illustrates a schematic representation depicting velocity profile on the front plane of a 3-d simulation model of the tubular arrangement of Figure 14a;
Figure 14e illustrates a schematic representation depicting pressure on the front plane of a 3-d simulation model of the tubular arrangement of Figure 14a;
Figure 14f illustrates a schematic representation depicting water distribution on the front plane of a 3-d simulation model of the tubular arrangement of Figure 14a;
Figure 14g illustrates a schematic representation depicting water interface inside a tray of a 3-d simulation model of the tubular arrangement of Figure 14a along with an enlarged view depicting water interface inside the tray;
Figure 14h illustrates a schematic representation depicting water distribution in a bottom header of a 3-d simulation model of the tubular arrangement of Figure 14a;
Figure 14i illustrates a schematic representation depicting velocity profile, in m/sec in a bottom header of a 3-d simulation model of the tubular arrangement of Figure 14a;
Figure 15a illustrates a schematic representation depicting water distribution in a 3-d simulation model of a tubular arrangement for a down-comer for a decanter system in accordance with an embodiment of the present disclosure under same set of simulation conditions or boundary conditions as were in case of simulation done on 3-d simulation model of a tubular arrangement of the prior art;
Figure 15b illustrates a schematic representation depicting velocity profile on a central plane of a 3-d simulation model of the tubular arrangement of Figure 15a;
Figure 15c illustrates a schematic representation depicting pressure contours on central plane of a 3-d simulation model of the tubular arrangement of Figure 15a;
Figure 15d illustrates a schematic representation depicting velocity profile on the front plane of a 3-d simulation model of the tubular arrangement of Figure 15a;
Figure 15e illustrates a schematic representation depicting pressure on the front plane of a 3-d simulation model of the tubular arrangement of Figure 15a;
Figure 15f illustrates a schematic representation depicting water distribution on the front plane of a 3-d simulation model of the tubular arrangement of Figure 15a;
Figure 15g illustrates a schematic representation depicting water interface inside a tray of a 3-d model simulation of the tubular arrangement of Figure 15a along with an enlarged view depicting water interface inside the tray;
Figure 15h illustrates a schematic representation depicting water distribution in a bottom header of a 3-d simulation model of the tubular arrangement of Figure 15a;
Figure 15i illustrates a schematic representation depicting velocity profile, in m/sec in a bottom header of a 3-d simulation model of the tubular arrangement of Figure 15a;
Figure 16 illustrates a front view of the tubular arrangement with conical tray outlet at the intersection of the connecting pipes and tray and without additional arm elements disposed between adjacent tubular elements of the tubular arrangement for a down-comer;
Figure 17a illustrates a front view of a tubular arrangement in accordance with another embodiment, wherein there are no conical tray outlet at the intersection of the connecting pipes and tray and adjacent tubular elements are connected to each other by additional tubular arm elements;
Figure 17b illustrates an enlarged view depicting details of the additional tubular arm elements disposed between adjacent connecting pipes of the tubular arrangement of Figure 17a;
Figure 18a illustrates a schematic representation depicting water distribution in a 3-d simulation model of a tubular arrangement for a down-comer for a decanter system in accordance with an embodiment of the present disclosure under same set of simulation conditions or end conditions as were case of simulation done on 3-d model of a tubular arrangement of the prior art;
Figure 18b illustrates a schematic representation depicting velocity profile on a central plane of a 3-d simulation model of the tubular arrangement of Figure 18a;
Figure 18c illustrates a schematic representation depicting pressure contours on central plane of a 3-d simulation model of the tubular arrangement of Figure 18a;
Figure 18d illustrates a schematic representation depicting velocity profile on the front plane of a 3-d simulation model of the tubular arrangement of Figure 18a;
Figure 18e illustrates a schematic representation depicting pressure on the front plane of a 3-d simulation model of the tubular arrangement of Figure 18a;
Figure 18f illustrates a schematic representation depicting water distribution on the front plane of a 3-d simulation model of the tubular arrangement of Figure 18a;
Figure 18g illustrates a schematic representation depicting water interface inside a tray of a 3-d simulation model of the tubular arrangement of Figure 18a along with an enlarged view depicting water interface inside the tray; and
Figure 18h illustrates a schematic representation depicting water distribution in a bottom header of a 3-d simulation model of the tubular arrangement of Figure 18a.
DETAILED DESCRIPTION
The tubular arrangement for a decanter system for supernatant evacuation of the present disclosure will now be described with reference to the embodiments which do not limit the scope and ambit of the disclosure. The description relates purely to the exemplary preferred embodiments of the disclosed system and its suggested applications.
The system herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The present disclosure envisages a tubular arrangement with improved weir configuration for a down-comer for a decanter system used for separating supernatant from sewage sludge in a sludge tank/ biological reactor.
Referring to Figure 1, a conventional tubular arrangement 10 for a down-comer for a decanter system is illustrated, wherein straight and parallel tubular connecting pipes 16 connect a tray 12 of the down-comer to a bottom header 14 that facilitates the discharge of the clear supernatant therethrough. Figure 2a illustrates a front view of the conventional tubular arrangement 10. Figure 2b illustrates a side view of the conventional tubular arrangement 10. Figure 2c illustrates a bottom view of the conventional tubular arrangement 10. Figure 2d illustrates another view of the conventional tubular arrangement 10.
Figure 3 illustrates a front view of a tubular arrangement 100 for a down-comer for a decanter system in accordance with an embodiment of the present disclosure. The tubular arrangement 100 includes a plurality of straight connecting pipes 116o and a plurality of bent connecting pipes 116i forms fluid communication between a tray 112, also referred to as collection tray 112 and a bottom header 114 for facilitating the drawing of the clear supernatant collected in the tray 112, wherein outwardly disposed plurality of straight connecting pipes 116o are straight and parallel to each other while inwardly disposed plurality of bent connecting pipes 116i are provided with bends “B” and are diverging outwardly. The plurality of bent connecting pipes 116i has a straight portion extending in an operative vertically downward direction from the tray 112, a first bent portion extending from an operative end of the straight portion at a pre-determined angle with respect to the straight portion, and a second bent portion extending from the first bent portion in an operative horizontal direction to be terminated in an operative the bottom header 114. The plurality of straight connecting pipes 116i and the plurality of bent connecting pipes 116o are also collectively referred to as connecting pipes 116 or tubular arrangement 116 hereinafter.Such a configuration of the connecting pipes / tubular elements 116 assists the flow of the clear supernatant through the connecting pipes 116 and hence reduces the frictional losses of the flow and prevents overflow of the tray resulting in uniform discharge through-out at constant pressure drop. Further, such a configuration of the tubular elements or connecting pipes 116 facilitates achieving shortest draining path for supernatant flow, minimal arm and header pipe length, thereby minimizing the friction losses faced by the supernatant flow through the draining path. Figure 3 also illustrates an enlarged view depicting connection between a tray 112 and the operative top end of the connecting pipes 116, wherein a conical tray outlet 118 is configured on an operative bottom of the tray 112 for directing clear supernatant collected in the tray 112 to the connecting pipes 116. The conical tray outlet 118 is having a converging configuration, wherein such a configuration assists in directing the clear supernatant to the connecting pipes 116 and prevents separation of flow of the supernatant entering the connecting pipes 116. The collecting tray 112 and flap are either shear cut or laser cut and bent. The collecting pipes 116 are either directly purchased or rolled from suitable thickness plates. The main drain pipe connected to the bottom header and the outlet to reservoir is manufactured the same way as the collecting pipes 116. All sub components of the decanter system are machined to their shape and size as required like the hinges, breathing pipes, and flanges.
Figure 4 illustrates a front view of the tubular arrangement 100. Figure 5 illustrates a rear view of the tubular arrangement 100. Figure 6a illustrates a left hand side view of the tubular arrangement 100. Figure 6b illustrates a left hand side view of the tubular arrangement 100 with an enlarged view depicting orientation of the tray 112 with respect to the connecting pipes 116. Figure 7 illustrates a right hand side view of the tubular arrangement 100. Figure 8 illustrates a top view of the tubular arrangement 100. Figure 9 illustrates a bottom view of the tubular arrangement 100. Figure 10 illustrates an isometric view of the tubular arrangement 100. Figure 11 illustrates a decanter system comprising the tray 112, the tubular arrangement 116 of the down-comer and the bottom header 114, wherein the decanter system is in lowermost position making a least angle. Figure 12 illustrates a front view of the tubular arrangement 100’ in another configuration illustrating the extended tray configuration. Figure 13 illustrates a front view of the tubular arrangement 200 in accordance with another embodiment, wherein adjacent tubular elements 216 are connected to each other by additional tubular arm elements 218. More specifically, an inverted Y shaped tubular arm element 218 connects adjacent tubular elements 216 of the tubular arrangement disposed between the tray 212 and the bottom header 214. More specifically, the additional tubular arm elements are disposed between the plurality of straight connecting pipes 216o and said plurality of bent connecting pipes 216i such that an operative top end 218a of the plurality of additional tubular arm element 218 is in fluid communication with the tray 212, and a first operative bottom end 218b is in fluid communication with the plurality of straight pipes 216i and a second operative bottom end 218c is in fluid communication with said plurality of bent connecting pipes 216o; such a configuration of the tubular arrangement facilitates in achieving laminar smooth flow through the tubular elements of the tubular arrangement for the down-comer.
Figure 14a illustrates a schematic representation depicting water distribution in a 3-d simulation model, particularly Computational Fluid Dynamic (CFD) model of a tubular arrangement 10 for a down-comer for a decanter system in accordance with the prior art under pre-determined set of simulation conditions or end conditions. More specifically, the simulation tests were conducted on the Computational Fluid Dynamic (CFD) model of the tubular arrangement 10 under end conditions such as air density = 1.225 kg/m3 and viscosity is 1.789 X10-5 Pa. s, water density 998.2 kg/m3 and viscosity 0.001 Pa.s, the Computational Fluid Dynamic (CFD) model considered for the simulation analysis is multi-phase VOF model for interface prediction, K- turbulence model, the inlet water flow rate is 0.104 m3/s and outlet pressure as atmospheric pressure.
Figure 14b illustrates a schematic representation depicting the velocity profile on a central plane of a 3-d simulation model of the tubular arrangement 10. Figure 14c illustrates a schematic representation depicting pressure contours on central plane of a 3-d simulation model of the tubular arrangement 10. Figure 14d illustrates a schematic representation depicting velocity profile on the front plane of a 3-d simulation model of the tubular arrangement 10. Figure 14e illustrates a schematic representation depicting pressure on the front plane of a 3-d simulation model of the tubular arrangement 10. Figure 14f illustrates a schematic representation depicting water distribution on the front plane of a 3-d simulation model of the tubular arrangement 10. Figure 14g illustrates a schematic representation depicting water interface inside a tray of a 3-d simulation model of the tubular arrangement 10 along with an enlarged view depicting water interface inside the tray 12. Figure 14h illustrates a schematic representation depicting water distribution in a bottom header of a 3-d simulation model of the conventional tubular arrangement 10. Figure 14i illustrates a schematic representation depicting velocity profile, in m/sec in a bottom header of a 3-d simulation model of the tubular arrangement 10.
Based on the simulation results is was observed that even at 10 degree angle of inclination of the conventional tubular arrangement 10 with respect to vertical, the average liquid holdup in the down-comer is 73 percent, the average liquid holdup in the connecting pipes 16a and 16d (i.e. side connecting pipes) is 73 percent and the average liquid holdup in the connecting pipes 16b and 16c (i.e. central connecting pipes) is 79.6 percent. Further, the average fluid velocity in the connecting pipes 16a and 16d i.e. side connecting pipes) is 2.59 m/sec and the average fluid velocity in the connecting pipes 16b and 16c (i.e. central connecting pipes) is 2.43 m/s. Still further, the average holdup in the bottom header is 93.4 percent and the average velocity in bottom header is 0.542 m/sec., the bottom outlet volume flow rate is 0.043m3/s and the tray volume overflow rate is 0.0614 m3/s. Based on the observation of the aforementioned simulation results obtained for the conventional tubular arrangement 10, it is concluded that the at an angle 10°, the connecting pipes are 70-80% filled, further, complete filling of the bottom header 14 is observed, this implies that the size of the bottom header 14 in case of the conventional tubular arrangement 10 is inadequate. Further, it is concluded that in case of the conventional tubular arrangement 10, the tray 12 is observed to be over flooded and pipe diameter of 80mm is inadequate to drain the liquid for given the flow rate.
The following table provides test results depicting variation in Rh (in m), S (in m/m), Flow velocity (in m/s) and flow rate (m3/s) with change in connecting pipe diameter based on assumption that the connecting pipes of the conventional tubular arrangement is 70 percent filled and inlet flow rate through the pipes is 187.5 m3/hr or 0.052 m3/s.
Pipe diameter,
mtrs Rh,
mtrs S
m/m V,
m/sec Q,
m3/sec
0.1 0.05 0.016 1.433484 0.007877
0.15 0.075 0.024 2.299933 0.028436
0.2 0.1 0.032 3.216575 0.0707
0.25 0.125 0.04 4.172447 0.143297
0.3 0.15 0.048 5.16079 0.255227
0.4 0.2 0.064 7.217632 0.634574
Figure 15a illustrates a schematic representation depicting water distribution in a 3-d simulation model of a tubular arrangement 100 for a down-comer for a decanter system in accordance with an embodiment of the present disclosure under the same set of simulation conditions or end conditions as were in case of simulation done on the 3-d simulation model of the tubular arrangement 10 of the prior art. More specifically, the simulation tests were conducted on the Computational Fluid Dynamic (CFD) model of the tubular arrangement 100 under end conditions such as air density = 1.225 kg/m3 and viscosity is 1.789 X10-5 Pa. s, water density 998.2 kg/m3 and viscosity 0.001 Pa.s, the Computational Fluid Dynamic (CFD) model considered for the simulation analysis is multi-phase VOF model for interface prediction, K- turbulence model, the inlet water flow rate is 0.104 m3/s and outlet pressure as atmospheric pressure.
Figure 15b illustrates a schematic representation depicting velocity profile on a central plane of a 3-d simulation model of the tubular arrangement 100. Figure 15c illustrates a schematic representation depicting pressure contours on central plane of a 3-d simulation model of the tubular arrangement 100. Figure 15d illustrates a schematic representation depicting velocity profile on the front plane of a 3-d simulation model of the tubular arrangement 100. Figure 15e illustrates a schematic representation depicting pressure on the front plane of a 3-d simulation model of the tubular arrangement 100. Figure 15f illustrates a schematic representation depicting water distribution on the front plane of a 3-d simulation model of the tubular arrangement 100. Figure 15g illustrates a schematic representation depicting water interface inside a tray of a 3-d model simulation of the tubular arrangement 100 along with an enlarged view depicting water interface inside the tray 112. Figure 15h illustrates a schematic representation depicting water distribution in a bottom header of a 3-d simulation model of the tubular arrangement 100. Figure 15i illustrates a schematic representation depicting velocity profile, in m/sec in a bottom header 114 of a 3-d simulation model of the tubular arrangement 100.
Based on the simulation results it was observed that at 16 degree angle of inclination of the tubular arrangement 100 with respect to vertical, the average liquid holdup in the down-comer is 60.6 percent, the average liquid holdup in the connecting pipes 116o (i.e. plurality of straight connecting pipes) is 51.3 percent and the average liquid holdup in the connecting pipes 116i (i.e. plurality of bent connecting pipes) is 45.15 percent. Further, the average fluid velocity in the connecting pipes 116o (i.e. plurality of straight connecting pipes) is 2.59 m/sec and the average fluid velocity in the connecting pipes 116i (i.e. plurality of bent connecting pipes) is 2.67 m/s. Still further, the average holdup in the bottom header is 62.7 percent and average velocity in bottom header 114 is 1.33 m/sec., the bottom outlet mass flow rate is 37.23 kg/sec. and the tray mass over flow rate is 14.33 kg/sec. Based on the above observation of simulation results obtained for the tubular arrangement 100, it is concluded that in case the tubular arrangement is at the angle of 16° with respect to the vertical, the connecting pipes are 50% filled, further, draining in the bottom header pipe 114 is also observed smoother and central arm pipe ,i.e., plurality of bent connecting pipes 116i is aiding in the drainage from the bottom header pipe 114. However, the angle is not limited to 16o, and may be any angle from a range of 5o to 75o. Further, it was observed that the flow resistance at the entrance of the connecting pipes 116 is observed and tray over flow of 30% is observed because of this flow resistance. In order to prevent flow resistance at the entrance of the connecting pipes 116, conical tray outlet 118 at the intersection of the connecting pipes 116 and tray is suggested. Further arming is disposed between the adjacent connecting pipes to achieve laminar smooth flow through the connecting pipes of the tubular arrangement 100.
Figure 16 illustrates a front view of the tubular arrangement 100 with conical tray outlet 118 at the intersection of the connecting pipes 116 and tray 112 and without additional arm elements disposed between adjacent tubular elements of the tubular arrangement 200 for a down-comer.
Figure 17a illustrates a front view of a tubular arrangement 200 in accordance with another embodiment, wherein there is no conical tray outlet at the intersection of the connecting pipes 216 and tray 212 and the adjacent tubular elements/connecting pipes 216 connecting the tray 212 to the operative bottom header 214 are connected to each other by additional tubular arm elements 218. Figure 17b illustrates an enlarged view depicting details of the additional tubular arm elements 218 disposed between connecting pipes 216 of the tubular arrangement 200.
Figure 18a illustrates a schematic representation depicting water distribution in a 3-d simulation model of a tubular arrangement 200 for a down-comer for a decanter system under the same set of simulation conditions or end conditions as were in case of simulation done on 3-d model of a tubular arrangement of the prior art. More specifically, the simulation tests were conducted on the Computational Fluid Dynamic (CFD) model of the tubular arrangement 200 under end conditions such as air density = 1.225 kg/m3 and viscosity is 1.789 X10-5 Pa. s, water density 998.2 kg/m3 and viscosity 0.001 Pa.s, the Computational Fluid Dynamic (CFD) model considered for the simulation analysis is multi-phase VOF model for interface prediction, K- turbulence model, the inlet water flow rate is 0.104 m3/s and outlet pressure as atmospheric pressure. More specifically, the simulation tests were conducted on the Computational Fluid Dynamic (CFD) model of the tubular arrangement wherein conical tray outlet is provided at the intersection of the connecting pipes and tray. Further, simulation tests were conducted on the Computational Fluid Dynamic (CFD) model of the tubular arrangement wherein additional tubular arm elements 218 are disposed between adjacent connecting pipes 216 of the tubular arrangement 200.
Figure 18b illustrates a schematic representation depicting velocity profile on a central plane of a 3-d simulation model of the tubular arrangement 200. Figure 18c illustrates a schematic representation depicting pressure contours on central plane of a 3-d simulation model of the tubular arrangement 200. Figure 18d illustrates a schematic representation depicting velocity profile on the front plane of a 3-d simulation model of the tubular arrangement 200. Figure 18e illustrates a schematic representation depicting pressure on the front plane of a 3-d simulation model of the tubular arrangement 200. Figure 18f illustrates a schematic representation depicting water distribution on the front plane of a 3-d simulation model of the tubular arrangement 200. Figure 18g illustrates a schematic representation depicting water interface inside a tray of a 3-d simulation model of the tubular arrangement 200 along with an enlarged view depicting water interface inside the tray 212. Figure 18h illustrates a schematic representation depicting water distribution in a bottom header of a 3-d simulation model of the tubular arrangement 200.
There could be various alternatives for the configuration of the lifting mechanism for handling the tubular arrangement. For example, the lifting mechanism/mobility of the tubular arrangement for forward motion and reverse motion could be addressed alternatively by adding a hydraulic cylinder pull design in place of electro-mechanical (gear box, rack and pinion design), thereby reducing the torques during decanter operation, resulting in lower cost and more reliability to the system at all hydraulic loads.
Based on the simulation results, it was observed that in case the conical tray outlet 118 is provided at the intersection of the connecting pipes 116 and the tray 112, the average liquid holdup in the down-comer is 58.27 percent, the average liquid holdup in the connecting pipes 116o (i.e. plurality of straight connecting pipes) is 68.41 percent and the average liquid holdup in the connecting pipes 116i (i.e. plurality of bent connecting pipes) is 60.61 percent. Further, the average fluid velocity in the connecting pipes 116o (i.e. plurality of straight connecting pipes) is 2. 9 m/sec and the average fluid velocity in the connecting pipes 116i (i.e. plurality of bent connecting pipes) is 2.98 m/s. Still further, the average holdup in bottom header 114 is 68.62 percent and average velocity in bottom header 114 is 1.66 m/sec., the bottom outlet mass flow rate is 52 percent and tray mass over flow rate is 0 percent.
Further, in case of arming, i.e., inverted y shaped additional tubular arm element 218 is disposed between the adjacent connecting pipes 216 to achieve laminar smooth flow through the connecting pipes 216 of the tubular arrangement 200, the average liquid holdup in the down-comer is 63 percent, the average liquid holdup in the connecting pipes 216o (i.e. plurality of straight connecting pipes) is 59. 1 percent and the average liquid holdup in the connecting pipes 216i (i.e. plurality of bent connecting pipes) is 53.8 percent. Further, the average fluid velocity in the connecting pipes 216o (i.e. plurality of straight connecting pipes) is 2.6 m/sec and the average fluid velocity in the connecting pipes 216i (i.e. plurality of bent connecting pipes) is 2.59 m/s. Still further, the average holdup in the bottom header 114 is 64.42 percent and average velocity in bottom header 214 is 1.77 m/sec., the bottom outlet mass flow rate is 52 percent and tray mass over flow rate is 0 percent.
Based on the above observation of the simulation results obtained for the tubular arrangements, it is concluded that in cases wherein the tubular arrangement is provided with additional arming, i.e., inverted y shaped additional tubular element disposed between the adjacent connecting pipes and conical tray outlet is disposed at the intersection of the connecting pipes and tray, adequate draining without tray overflow is achieved. Further, the liquid holdup in case of tubular arrangement provided with additional arming is higher thereby suggesting more resistance. Further, flow velocity in the connecting pipes in case of tubular arrangement with conical tray outlet is higher than the tubular arrangement with additional arm configuration.
TECHNICAL ADVANCEMENTS AND ECONOMIC SIGNIFICANCE
The technical advantages of the tubular arrangement for down-comer for a decanter system envisaged by the present disclosure include the realization of:
? a tubular arrangement for down-comer for a decanter system that achieves shortest draining path for supernatant flow, minimal arm and header pipe length, thereby minimizes the friction losses faced by the supernatant flow through the draining path;
? a tubular arrangement for down-comer that is having such a configuration that the tubular arrangement operates effectively irrespective of lower angle of inclination of the connecting pipes;
? a tubular arrangement for down-comer for a decanter system that is having such a configuration that tray overflow is prevented;
? a tubular arrangement for down-comer that is having such a configuration that achieves the desired draining water velocities, draining water flow within desired decanting time;
? a tubular arrangement for down-comer for a decanter system that achieves optimized arm pipe and bottom header size, thereby resulting in material saving;
? a tubular arrangement for down-comer for a decanter system that is reliable and has extended service life;
? a tubular arrangement for down-comer for a decanter system that facilitates evacuation of the clear from a reservoir;
? a tubular arrangement for down-comer for a decanter system that achieves laminar smooth flow through the tubular elements of the tubular arrangement for down-comer;
? a tubular arrangement for a down-comer for a decanter system that is reliable and cost effective;
? a tubular arrangement for a down-comer having such a configuration that eliminates chances of flow separation, back pressure and frequent blocking of the tubular connecting pipes of the down-comer;
? a tubular arrangement for down-comer that is having compact configuration;
? a tubular arrangement for down-comer that prevents separation of flow through the connecting pipes of the down-comer;
? a tubular arrangement for a down-comer having such a configuration that kinetic energy of arm pipe flow is utilized to aid bottom header drainage;
? a tubular arrangement for down-comer that is having such a configuration that the flow of the clear supernatant through the connecting pipes is assisted by the configuration of the connecting pipes and accordingly uniform discharge for evacuating the clear supernatant from the reservoir is achieved;
? a tubular arrangement for down-comer that is having such a configuration that assists in quick evacuation of the clear supernatant from the reservoir;
? a tubular arrangement for down-comer that is simple in construction; and
? a tubular arrangement for down-comer that is efficient in evacuating the clear supernatant from the reservoir.
? a tubular arrangement for the bottom header with optimized length
? the lifting mechanism/mobility of the tubular arrangement for forward motion and reverse motion could be addressed alternatively by adding a hydraulic cylinder pull design in place of electro-mechanical (gear box, rack and pinion design, thereby reducing the torques during decanter operation, resulting in lower cost and more reliability to the system at all hydraulic loads.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein. ,CLAIMS:1. A decanter system comprising in the form of a tubular arrangement for down-comer for evacuating supernatant from a reservoir, said arrangement comprising;
• a tray configured to receive a supernatant from said reservoir;
• at least one bottom header configured to receive said supernatant from said tray and discharge said supernatant therefrom;
• a plurality of connecting pipes configured to transfer said supernatant from said tray to said at least one bottom header, said plurality of connecting pipes comprising:
o a plurality of straight connecting pipes extending from said tray in an operative vertically downward direction, wherein an operative top end of said plurality of straight connecting pipes is in fluid communication with said tray and an operative bottom end of said plurality of straight connecting pipes is in fluid communication with one of said bottom header;
o a plurality of bent connecting pipes extending in an operative downward direction from said tray and terminating in an operative end of said at least one bottom header, said plurality of bent connecting pipes is in fluid communication with said tray and said bottom header, said plurality of bent connecting pipes having;
- a straight portion extending in an operative vertically downward direction from said tray, wherein an operative top end of said straight portion is in fluid communication with said tray;
- a first bent portion extending from an operative bottom end of said straight portion at a pre-determined angle with respect to said straight portion; and
- a second bent portion extending from an operative bottom end of said first bent portion in an operative horizontal direction terminated in said operative end of said at least one bottom header.
2. The decanter system as claimed in claim 1, wherein said tubular arrangement for down-comer comprises a conical tray outlet disposed at the intersection of said plurality of connecting pipes and said tray.

3. The decanter system as claimed in claim 1, wherein said tubular arrangement for down-comer comprises a plurality of tubular arm elements, wherein said tubular arm element has an inverted Y-shaped configuration and disposed between said plurality of straight connecting pipes and said plurality of bent connecting pipes such that an operative top end of said tubular arm element is in fluid communication with said tray, and a first operative bottom end of said tubular arm element is in fluid communication with said straight connecting pipes and a second operative bottom end of said tubular arm element is in fluid communication with said bent connecting pipes.

4. The decanter system as claimed in claim 1, wherein said tubular arrangement for down-comer is inclined at an angle in a range of 5-75 degrees with respect to the vertical.