Claims:We claim:
1. An equipment for treating a material to separate an oil from the material; the equipment comprising two or more thermal evaporators optionally connected sequentially.
2. The equipment claimed in claim 1, wherein each of the thermal evaporators comprises a jacketed body, two hollow shafts and a plurality of hollow paddles attached to the shafts, wherein a hot fluid is circulated through the jacket, the shafts and the paddles to heat the material.
3. The equipment claimed in any of the claims 1 and 2, wherein the equipment further comprises two or more filters, two or more scrubbers and two or more condensers, and two or more receivers.
4. The equipment claimed in any of the claims 1 to 3, wherein the equipment comprises two thermal evaporators, each of the thermal evaporator attached to one each of the equipment of claim 3.
5. The equipment claimed in claim 5, wherein the material in the first thermal evaporator is heated to a temperature ranging up to 200° C with a vapor temperature ranging from up to 120° C.
6. The equipment claimed in claim 5, wherein the material in the second thermal evaporator is heated to a temperature ranging up to 230° C with a vapor temperature ranging up to 160° C.
7. The equipment claimed in any of the claims 1 to 7, wherein the material is heated under negative pressure up to 300 mm Hg in each of the thermal evaporators.
8. The equipment claimed in any of the claims 1 to 8, wherein the equipment is for processing the oil mixed with the material or absorbed, adsorbed and/or adhered to the material.
9. The equipment claimed in any of the claims 1 to 9, wherein the material comprises drill cuttings, oil-contaminated soils, and/or oily sludge from oil tanks and tank bottoms.
10. The equipment claimed in any of the claims 1 to 10, wherein the oil comprises hydrocarbons, synthetic base oil, organic materials and/or mineral or non-mineral oils.
11. The equipment claimed in any of the claims 1 to 11, wherein the equipment reduces the oil content of the material to less than 0.5%.
12. A method of treating a material to separate oil from the material; the method comprising heating the material to evaporate the oil in two or more thermal evaporators optionally connected sequentially.
13. The method claimed in claim 13, wherein each of the thermal evaporators comprising a jacketed body, two hollow shafts and a plurality of hollow paddles attached to the shafts, wherein a hot fluid is circulated through the jacket, the shafts and the paddles to heat the material.
14. The method claimed in claim 16, wherein the material is heated to a temperature ranging up to 200° C in the first thermal evaporator with a vapor temperature ranging up to 120° C.
15. The method claimed in claim 16, wherein the material is heated to a temperature ranging up to 230° C in the second thermal evaporator with a vapor temperature ranging up to 160° C.
16. The method claimed in any of the claims 13 to 18, wherein the material is heated under negative pressure up to 300 mm Hg in in each of the thermal evaporators.

Dated this on 20th day of March, 2018

Subhajit Saha
Patent Agent (IN/PA-1937)
Agent for the applicant
, Description:FORM – 2

THE PATENTS ACT, 1970
(39 of 1970)
AND
THE PATENTS RULES, 2003

COMPLETE SPECIFICATION

(See Section 10; rule 13)

TITLE OF THE INVENTION

AN EQUIPMENT AND METHOD FOR TREATING MATERIAL

SAR Chandra Environ Solutions Private Limited
4B1, APIIC Industrial Park,
Vakalapudi, Kakinada,
Andhra Pradesh, India - 530005

An Indian National

The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
[1] The present invention relates to an equipment and a method for treating a material to separate an oil from the material. Particularly, the present invention relates to a method of treating drill cuttings, oil-contaminated soils, oily sludge or tank bottom sludge from oil tanks.

BACKGROUND OF THE INVENTION
[2] The removal or recovery of oily fractions from materials such as waste products is useful in the processing of waste generated by oil and gas up-stream /mid-stream/own-stream industry. When an oil or gas well is drilled into a formation containing valuable hydrocarbons to be recovered, the drilling process generates drill cuttings (small chips of rock etc.) which are washed back to the surface and recovered from the well by the circulation of drilling mud in the well. In addition to washing the drill cuttings back to the surface, drilling mud (also called drilling fluid) is used to cool the drill bit and to resist blow outs during the drilling operation. The drill cuttings recovered at the surface are usually contaminated by synthetic base oil used in drill mud preparation and may be hydrocarbons from the reservoir, which permeate the rock that was drilled in order to form the bore hole, and also by the drilling mud that is pumped down the hole in order to wash the cuttings out of the well. The contamination of the cuttings by the drilling mud and the hydrocarbons that permeate the cuttings currently present challenges for the operator, because the environmental concerns dictate that the hydrocarbons contaminating the cuttings must be removed or reduced below the threshold value before the cuttings can be safely disposed of. In addition, efficiency savings can be made by recycling the used drilling mud for subsequent use in future cycles, and by recovering the synthetic base oil /hydrocarbons on the drill cuttings for export from the well with the other valuable production fluids. Therefore, it is useful to be able to separate and typically recover the oily materials contaminating the waste drill cuttings before disposal of the cuttings.
[3] Various methods are known for the removal of oily contaminants from drill cuttings. The one known methods (TCC® of ThermTech) uses frictional energy to evaporate the various fractions or such hydrocarbons from the cuttings as gasses, and to separate the hydrocarbons from the mixture of vapors by distillation. The known methods are operated at higher temperature which is very close to the flash point of the synthetic base oil /hydrocarbons, which have safety concerns. The operational cost of the known method is also very high due to more fuel required to heat at higher temperature. The method is also difficult in operational part and maintenance. Other known method is wet process which uses acids for such separation. The wet process is also associated with issues e.g. maintenance, lack of safety, additional /residual waste, high cost etc.
[4] Typically, it is also desirable to evaporate the hydrocarbons at temperatures lower than their atmospheric boiling points to avoid changing the molecular characteristics or "cracking" the hydrocarbons, so that more of the valuable longer chain hydrocarbons are recovered from the distillation process can be exported from the well along with the other valuable production fluids for downstream processing and refining. Therefore, there is an urgent need of a method of treating material to separate oil from the material at lower temperature to increase the safety in process and to recover valuable longer chain hydrocarbons.
[5] The present invention relates to an equipment and method for treating a material to separate an oil from the material by heating the material at negative pressure to evaporate the oil, wherein the negative pressure lowers down the boiling points of volatiles thus conserving energy as well improving safety and ease of operation.

SUMMARY OF THE INVENTION
[6] According to the present invention there is provided an equipment and method for treating a material to separate an oil from the material. The equipment comprises two or more thermal evaporators optionally connected sequentially. The method comprises of heating the material in the equipment of the present invention at negative pressure to evaporate the oil, wherein the negative pressure lowers down the boiling points of volatiles thus conserving energy as well as improving safety and ease of operation. Typically the oil is recovered from the gas phase evaporates in separate step such as condensation / distillation, occurring after the evaporation of the oil and the removal of gas phase evaporates from the material.
[7] Typically the material can comprise solids, liquids and/or gases in any ratio. Generally, the material can comprises drill cuttings, oil-contaminated soils, bleaching earth and/or oily sludge from oil tanks and tank bottoms.
[8] Typically, the material being treated in the thermal evaporators is heated at negative pressure. The negative pressure lowers down the boiling point of the oil/liquid adsorbed over the material. Thus, the hot vapor of the oil/liquid can be formed at relatively lower temperature and it changes phase into a gas phase.
[9] The oil can be separated from the gas phase evaporates removed from the thermal evaporator by condensation /distillation. Typically a condensation /distillation device can be connected to an outlet of the thermal evaporator, through which the gas phase evaporates can be removed. Typically, the thermal evaporator can have more than one unit and therefore more than one outlet, preferably in series, and the same (or a separate) separation device such as a distillation device can optionally be connected to each outlet.
[10] The oil can comprise hydrocarbons, synthetic base oil, organic materials and/or mineral or non-mineral oils. Optionally the material is mixed with additives to improve the separation and/or the recovery of the oil from the material before and/ or during the process.
[11] The material is typically treated in two thermal evaporators optionally connected sequentially. The material being treated is typically fed into the thermal evaporators and is heated to a desired temperature. The material may be pre-heated before being fed into the thermal evaporators. The material may already contain water. The thermal evaporators typically have at least one inlet and at least one outlet to feed in and transport out all the phases (solids, liquids and gasses/vapor).
[12] The preheating temperature, the heating rate, the vapor flow rate and the process temperature and pressure can be varied in different examples of the invention, depending on the oil content of the material or the desired result.
[13] The thermal evaporator comprising a jacketed body, two shafts and a plurality of hollow paddles attached to the shafts, wherein a hot fluid is circulating through the jacket and the hollow space of shafts and paddles to heat the material.
[14] The various aspects of the present invention can be practiced alone or in combination with one or more of the other aspects, as will be appreciated by those skilled in the relevant arts. The various aspects of the invention can optionally be provided in combination with one or more of the optional features of the other aspects of the invention. Also, optional features described in relation to one aspect can typically be combined alone or together with other features in different aspects of the invention. Any subject matter described in this specification can be combined with any other subject matter in the specification to form a novel combination.
[15] Various aspects of the invention will now be described in detail with reference to the accompanying figure. Still other aspects, features, and advantages of the present invention are readily apparent from the entire description thereof, including the figure, which illustrates a number of exemplary aspects and implementations. Any subject matter described in the specification can be combined with any other subject matter in the specification to form a novel combination. The invention is also capable of other and different examples and aspects, and its several details can be modified in various respects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and not as restrictive. Furthermore, the terminology and phraseology used herein is solely used for descriptive purposes and should not be construed as limiting in scope.

BRIEF DESCRIPTION OF THE DRAWINGS
[16] Figure-1 is a view of an equipment for treating a material for separating oil from the material;

DETAILED DESCRIPTION
[17] The present invention relates to an equipment and a method of treating a material to separate an oil from the material. Particularly, the present invention relates to an equipment and a method of treating drill cuttings, oil-contaminated soils, bleaching earth and/or oily sludge from oil tanks and tank bottoms.
[18] Definitions: It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. As used in this specification and the appended claims, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a thermal evaporator" includes one or more such thermal evaporator and the like.
[19] Unless defined otherwise, all technical, scientific or other terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although other methods and materials similar, or equivalent, to those described herein can be used in the practice of the present invention, the preferred materials and methods are described herein.
[20] In describing and claiming the present invention, the following terminology will be used in accordance with the definitions set out below.
[21] In the present invention, the term “material” refers to a solid or semisolid sludge material adsorbed with liquid or gases on its surface. The material includes but not limited to drill cuttings, oil-contaminated soils, bleaching earth and/or oily sludge from oil tanks and tank bottoms. The oil, liquid and/or gases may be mixed, absorbed, adsorbed or adhered with the material.
[22] In the present invention, the term “drill cutting” refers to broken bits of solid material removed from a borehole drilled by rotary, percussion, or auger methods. Boreholes drilled in this way include oil or gas wells, water wells, and holes drilled for geotechnical investigations or mineral exploration.
I. Equipment for treating a material:
[23] Referring to fig. 1, where fig. 1 describes construction of the equipment for treating a material to separate an oil from the material. The equipment comprises a Vibratory Feeder (1), a Redlar Conveyer-1 (2), a pre-conditioner (3), a Lump Breaker (4), a Redlar Conveyer-2 (5), an Inlet Rotary Air Lock Valve (Inlet RAV) (6), two Stage-1 and Stage-2 Thermal Evaporators (7, 17) connected in a series, two Stage-1 and Stage-2 Dust Collectors (8, 18), two Stage-1 and Stage-2 Scrubbers (9, 19), two Oil Collection Tanks (10, 20), two Oil Circulation Pumps (11, 21), two Filters (12, 22), two Stage-1 and Stage-2 Condensers (13, 23), two Stage-1 and Stage-2 Receivers (14, 24), an Outlet RAV (15), and a Skips (16) connected to each other substantially as shown in fig. 1.
A. Vibratory Feeder (1):
[24] The Vibratory Feeder (1) is equipped with electrical motors driven vibrators for providing required vibrations. The vibrations can be adjusted such that the material gains momentum and falls on to the vibratory screen. The Vibratory Feeder (1) provides the material required movement to feed it to the pre-conditioner feed hopper with the help of Redlar Conveyor-1 (2).
B. Redlar Conveyor-1 (2):
[25] Redlar Conveyor-1 (2) is preferably a redlar chain conveyor system consisting flat blades which moves the material to the jacketed pre conditioner feed hopper.
C. Pre-conditioner (3):
[26] The Pre-conditioner (3) comprises of two shafts fitted with inclined flat blades rotating in opposite direction. The blades are designed to help in moving the material forward. The pre-conditioner (3) imparts strong agitation to the material so as to bring uniformity and homogeneity to the material. The Pre-conditioner (3) is jacketed and has circulating hot fluid/oil in the jacket to pre-heat the material.
D. Lump Breaker (4):
[27] The Lump Breaker (4) in breaking the lumps to a smaller size before the material goes further.
E. Redlar Conveyor-2 (5):
[28] Redlar Conveyor-2 (5) is preferably a redlar chain conveyor system consisting flat blades which moves the material from the Lump Breaker (4) to the Thermal Evaporator through evaporator feed hopper.
F. Inlet Rotary Air Lock Valve (inlet RAV) (6):
[29] The evaporator feed hopper is equipped with an Inlet Rotary Air Lock Valve (inlet RAV) (6). The inlet RAV (6) provides continuous feed and simultaneously provides vacuum or negative pressure seal in the Thermal Evaporator (7) that follows the RAV (6). The purpose of RAV (6) is to provide continuous feeding and also ensure pressure sealing of the system. The material collected between the RAV (6) valves from the feed hopper is continuously fed into the Thermal Evaporator (7) at a constant flow rate. One or more variable frequency drives (VFDs) are used to adjust the speed of the hollow rotor shaft of the Thermal Evaporators (7) with feed collecting in hopper in order to avoid possible chocking from material accumulation in its entire length of the operation.
G. Thermal Evaporators (7, 17):
[30] The each Thermal Evaporator (7, 17) comprises a jacketed body, two hollow shafts and a plurality of hollow paddles. A hot fluid, preferably a hot oil is circulated through the jacket of the body and hollow passage or shaft and paddles of the Thermal Evaporators (7, 17) to heat the material in the Thermal Evaporators (7, 17). The angle of the paddles is also designed to help mixing the material while simultaneously moving the material forward. The paddles arrangement and sizes are designed / fabricated in such a way that the material is always in contact with the surface of the blades to enable heat transfer. The Thermal Evaporators (7, 17) in addition is provided with feed ports to receive material continuously and with a discharge port. The rotating hollow paddle shafts ensure the received material continuously moves forward as well as attain the required temperatures to dry the solids. The Thermal Evaporators (7, 17) are also connected to scrubbing, condensing and vacuum system so that Thermal Evaporators (7, 17) always operates under vacuum. Since the oil used for lubrication in drilling has high boiling points, it is necessary to operate Thermal Evaporators (7, 17) under vacuum to take advantage of proportionate fall in boiling points at lower pressures. The Thermal Evaporators (7, 17) are also equipped with supporting auxiliary equipment to ensure safe operations. Both the Thermal Evaporators (7, 17) are provided with a rupture disc/safety valve to protect the equipment.
[31] The number of Thermal Evaporator (7) can be increased or decreased depending upon oil and moisture content of the material. With the material containing higher oil moisture content, the number of Thermal Evaporator (7) can be increased to two or more in series.
[32] It is designed such that each thermal evaporator can reduce moisture up to 20% and oil anywhere between 4 to 6%. A two stage thermal evaporator is observed to reduce oil content in the solids from 12% to 0.5%. The design is such that when oil content increases for every 4 to 6 % increase, another stage can be added and final oil content in the solids be kept less than 0.5% for its safe disposal.
[33] The method of the present invention includes one or more Thermal Evaporators to treat the material.
[34] The exemplary method of the present invention includes two Thermal Evaporators (7, 17) to treat the material.
i. Stage-I Thermal Evaporator (7):
[35] The Stage-I Thermal Evaporator (7) is connected to the feed hopper through the Inlet RAV (6). The Stage-I Thermal Evaporator (7) is connected to Stage-II Thermal Evaporation (17) through pipe at the outlet.
ii. Stage-II Thermal Evaporator (17):
[36] The Stage-II Thermal Evaporator (17) is connected to the Stage-I Thermal Evaporator (7) from the inlet. The Stage-II Thermal Evaporator (17) is connected to Skips (16) through an Outlet RAV (15).
H. Outlet Rotary Air Lock Valve (Outlet RAV) (15):
[37] The Thermal Evaporator (17) is fitted with an Outlet RAV (15) is fixed at the bottom of the Thermal Evaporator (17) to control flow of the treated material in the thermal evaporator chamber and provide vacuum seal in the chamber that is behind the outlet RAV (15). The outlet RAV (15) also provides continuous and constant flow rate and also ensure vacuum sealing of the system. The speeds are adjusted with the VFD’s provided to the system in order to avoid possible chocking of material accumulation in its entire length of the operation.

I. Skips (16):
[38] The dried solids will be discharged from outlet RAV (15) and get collected in to metal Skips (16). The collected material is tested by quality control lab for further disposal and into a land fill after meeting the required standards or designated use as per the regulatory requirements.
J. Dust Collectors (8, 18):
[39] The Dust Collectors (8, 18) are designed with higher diameter to reduce the particle velocity. The Dust Collectors (8, 18) are provided with Jacketing arrangement to circulate the hot fluid which maintains the vapor temperature during the process. In a preferred embodiment, the Dust Collectors (8, 18) are made of carbon steel. The oil and moisture evaporated from the Stage-I and Stage-II Thermal Evaporation are collected by the Dust Collectors (8, 18) respectively. Dust Collectors obstruct dust particles in the in the evaporated oil and moisture coming after Stage-I and Stage-II Thermal Evaporation.
K. Scrubbers (9, 19):
[40] The packed bed wet scrubbers (9, 19) are used to scrub the dust particles that are carried with the volatiles from dust collectors (8, 18) respectively.
[41] The dust laden vapors enter the Scrubber at the lower end of packing; the packing used is stainless steel (SS) Saddle Rings. Vapors travel upwards and the dust settles on the SS rings. At Bottom a hand hole is provided for cleaning Purpose.
L. Oil Collection Tanks (10, 20):
[42] The dust laden scrubbed oil from the scrubber gets collected in the Oil Collection Tank (10, 20), from where it is pumped through filter and recycled in to scrubber as scrubbing medium.
M. Oil Circulation Pumps (11, 21):
[43] The duct laden scrubbed medium oil is pumped with the help of Oil Circulation Pump (11, 21).
N. Filters (12, 22):
[44] The Filters (12, 22) are Pressure Leaf Filters. The oil is pumped through the Filters (12, 22) using circulation pump where the dust particles get separated. The clean oil will be recycled in to scrubber as scrubbing medium.
O. Condensers (13, 23):
[45] The Condensers (9, 19) used in the present invention are constructed from carbon steel with 15 sq. meter area. The Condensers (13, 23) are surface condenser with tube side condensate and shell side cooling water to condense the vapors generated in Thermal Evaporators (7, 17). The condensers (13, 23) are mounted vertically on condensate Receiver (14, 24) for easy tubes cleaning. The each of the Condensers (13, 23) has 43 tubes. The Condensers (13, 23) condense the vapor coming from the Scrubber (9, 19) and the vapors generated in Thermal Evaporator (7, 17). The Condensers (9, 19) are mounted directly on the Receivers (14, 24) respectively. The Condensers (9, 19) are tested under pressure of 3 Kg/cm2 Pneumatic. The Approximate Weight of the Condensers (9, 19) including Skid, Sprockets is 1 Metric Tons for Each.
P. Receivers (14, 24):
[46] The condensate liquid is allowed to collect into the vertical condensate Receivers (14, 24). The Receivers (14, 24) are preferably made from carbon steel. The Condensate Receiver has the following Specification and the features of the Equipment are 1) The Receivers (14, 24) are to Collect condensate from Condenser (13, 23) respectively which is mounted on its top. 2) It has one 8” Hand hole on top Dish End and 6” Nozzle on bottom dish end for cleaning purpose. Collection of Condensate from Condensers (13, 23) mounted on Receivers (14, 24) is done by the above featured equipment with 2KL Capacity. The Approximate Weight of the Equipment including Skid, Sprockets is 1 Metric Tons for Each.
II. Method of treating a material:
[47] Referring to fig. 1, where fig. 1 describes construction of the equipment for treating a material to separate an oil from the material; the method of the present invention is explained. The feed material bagged in an exemplary capacity of one ton bag is dumped on the Vibratory Feeder (1) with the help of crane after weighing. Prior to bagging in the bags the semi wet material is mixed with already treated dry solids to impart free flowing properties to the material. The Vibratory Feeder (1) is equipped with electrical motors driven vibrators for providing required vibrations. The vibrations can be adjusted such that the material gains momentum and falls on to the vibratory screen. Then, the material is moved to the pre-conditioner feed hopper with the help of Redlar Conveyor-1 (2). The material is further moved to pre-conditioner (3).The strong agitation created by the rotation brings uniformity and homogeneity to the material. The material is also pre-heated in this stage by circulating hot fluid/oil in the jacket. This warm and homogeneous material helps in maintaining the process operating smoothly and in a steady state.
[48] In the next step, the pre-conditioned material is passed to the Lump Breaker (4), which helps in breaking the lumps into smaller size before the material goes for further processing. The material coming from the Lump breaker (4) is carried to the evaporation feed hopper through the RedlarConveyor-2(5).
[49] The material is then, fed into Thermal Evaporator (7) through evaporator feed hopper. The Inlet RAV (6) controls the flow of material in the Thermal Evaporator (7). The Inlet RAV (6) provides continuous feed and simultaneously provides vacuum or negative pressure seal in the Thermal Evaporator (7). The material collected between the Inlet RAV (6) valves from the feed hopper is continuously fed into the Thermal Evaporator (7) at a constant flow rate. The speed of the hollow rotor shaft of the Thermal Evaporators (7) is adjusted through one or more variable frequency drives (VFDs) with feed collecting in hopper in order to avoid possible chocking from material accumulation in its entire length of the operation.
[50] The number of Thermal Evaporators (7) can be increased or decreased depending upon oil and moisture content of the material. With the material containing higher oil moisture content, the number of Thermal Evaporators can be increased to two or more in series.
[51] The method of the present invention includes one or more Thermal Evaporators (7) to treat the material.
[52] In a specific embodiment, the method of the present invention includes two Thermal Evaporators (7, 17) to treat the material.
[53] The thermal evaporation is carried out in two stages in the exemplary method of the present invention.
A. Stage-I: Thermal Evaporation
[54] The material entered from Inlet RAV (6) via feed hopper to Thermal Evaporator (7) for Stage-I Thermal Evaporating wherein the material is heated to a temperature ranging up to 200° C, preferably between 180° C and 200° C at negative pressure up to 300 mm Hg using vacuum system with a retention time of approx. 45 minutes. The heat energy required to the material is provided indirectly by circulating hot thermic fluid oil through jacket of the body and hollow shafts and paddles of the thermal evaporator. The heat given to the system will enable the moisture and oil to evaporate. The average vapor temperature is adjusted ranging up to 120° C, preferably between 110° C and 120° C. The hot material move forward by the hollow paddle conveyor and gets discharged through a pipe into Stage-II Thermal Evaporation (Thermal Evaporator (17)).

B. Stage-II: Thermal Evaporation
[55] The hot material enters into Thermal Evaporator (17) for Stage-II Thermal Evaporation, wherein the materials gains further heat to reach a temperature ranging up to 230° C, preferably between of 200° C and 230° C at negative pressure ranging up to 300 mmHg. Left out moisture remaining within the particles along with hydrocarbons gets evaporated in this Stage-II Thermal Evaporating. The average vapor temperature is adjusted ranging up to 160° C, preferably between 140° C and 160° C. Left out hydrocarbons gets evaporated in this stage leaving the dried oil-free solids discharged from the Thermal Evaporator (17) through outlet RAV (16) and Skips (16). The collected material is tested by quality control lab for further disposal and into a land fill after meeting the required standards.
[56] It is designed such that each thermal evaporator can reduce moisture up to 20% and oil anywhere between 4 to 6%. A two stage thermal evaporator is observed to reduce oil content in the solids from 12% to 0.5%. The design is such that when oil content increases for every 4 to 6 % increase, another stage can be added and final oil content in the solids be kept less than 0.5% for its safe disposal.
[57] The oil and moisture evaporated from the Stage-I and Stage-II Thermal Evaporation are collected by the Dust Collectors (8, 18) respectively. Dust Collectors (8, 18) obstruct dust particles in the in the evaporated oil and moisture coming after Stage-I and Stage-II Thermal Evaporation.
[58] The packed bed wet Scrubbers (9, 19) are used to scrub the dust particles that are carried with the volatiles from dust collectors (8, 18) respectively. The fine particles become light and the vacuum/negative pressure applied to the system for collecting the volatile vapors carry forward the fine and hot dust particles along with the vapors. Scrubbing is done to eliminate these dust particles carrying forward to the condenser and vacuum system. Recovered base oil is used as the scrubbing medium. The Scrubbers (9, 19) receive dust particles vapor coming from Dust Collectors (8, 18). The scrubbing medium is sprayed from the top to clean the vapors coming from the Thermal Evaporators (7, 17).
[59] The dust particles scrubbed to recovered oil which also acts as a scrubbing media and the hot vapors get condensed and collected. The vapors from both Thermal Evaporators (7, 17) are scrubbed using recovered base oil as scrubbing medium so as to remove dust from vapors. The oil under circulation is continuously passed through filter cloth by using leaf filter to obtain filtered oil. The oil under circulation as scrubbing medium through the scrubber gets thickened with the fines over a period of time which is then transferred, to a scrubber oil settling tank. The fines are allowed to settle down and the settled fines are sent to filter press for further separation of oil and fines. The oil obtained is free of fines as top layer from the settling tank and is re-circulated back into the scrubber as scrubbing medium.
[60] The dust laden scrubber oil from the scrubber gets collected in the Oil Collection Tank (10, 20), from where it is pumped through filter and recycled in to scrubber as scrubbing medium.
[61] The dust laden scrubbed medium oil is pumped with the help of Oil Circulation Pump (11, 21).
[62] The oil pumped through the circulation pump will pass through Pressure Leaf Filters (12, 22) where the dust particles get separated. The clean oil will be recycled in to scrubber as scrubbing medium.
[63] The uncondensed vapors from the scrubber are mostly dust free and enter into the shell and tube condenser (13, 23) for condensation. Cooling Tower water is circulated through the condenser for removal of heat energy and condensing the liquid.
[64] The condensate liquid is allowed to collect into the vertical Condensate Receivers (14, 24).

[65] The present description is the best presently-contemplated method for carrying out the present invention. Various modifications to the preferred embodiment will be readily apparent to those skilled in the art and the generic principles of the present invention may be applied to other embodiments, and some features of the present invention may be used without the corresponding use of other features. Accordingly, the present invention is not intended to be limited to the embodiment shown but is to be accorded the widest scope consistent with the principles and features described herein.