CA1312804C - Method and apparatus for treating waste material - Google Patents

Abstract

METHOD AND APPARATUS FOR TREATING WASTE MATERIAL

ABSTRACT

Preheated diluent and steam are introduced into a container carrying waste material typically comprised of a sludge mixture of liquid and solid material including hydrocarbons. The material is thereby heated to a pumpable state and piped to a heating pot where additional steam and diluent are added to maintain the flow characteristics of the material which is then delivered to a remote blending manifold. In the manifold, additional steam and diluent is added to optimize separability of the desired reclaimed material from the waste, whereupon the material is then delivered to a separator, preferably of the vibration screen type. The separator delivers waste material in the mixture to a solids box for disposal whereas valuable reclaimed hydrocarbons are delivered to a recovery tank for re-use, thereby avoiding disposal thereof and reducing the volume of waste material to be disposed of.

Description

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METHOD AND AypARATus FOR TREATI~G WASTE MATERIAL

BAC~GROUN~ OF THE INVENTION

This invention relates to the treatment of waste material and, more particularly, relates to the methods ` 5 and apparatus for removing solid and liquid mixtures from various containers and the subsequent separation thereof.
In the petrochemical industry and other industries, vast quantities of waste material, both solid and liquid in combination, are produced by various processes which accumulate in containers such as tanks, vats, ponds, and the like. Typically, at some point in time in the production cycly, it is necessary to clear out the container by removal of the sludge which remains.
Thus, methods and apparatus have long been known in the art for attempting to efficiently remove such material while at the same time seeking to retain any valuable materials in the sludge for re-use.
A principal technique for cleaning out these industrial containers has been to vacuum out as much material as possible with a vacuum truck or other such apparatus. Workmen are thereafter placed inside the container to remove the remaining material with shovels, buckets, etc. In some instances when part of the material has solidified, an aperture is cut into the tank, vessel9 ~5 or other container 7 whereupon mechanical e~uipment such as a front-end loader or the like is used to remove the remaining material.
Several serious drawbac~s exist with such methods ; and apparatus. First, the techniques are extremely labor intensive, and the conditions are frequently dangerous under which the individuals must work. Also, when the waste material is thereby removed and disposed, valuable residual material is lost. Still further, particularly ~ 3 ~

when a substantial amount of material has hecome solid, removal of this material, often under difficult and hazardous conditions within a tank, is extremely difficult. Still further, the volume of material which is disposed is typically unnecessarily high in ~hat otherh~ise re-cyclable material is thereby lost, adding to the cost and difficulty of the cleaning operation due to the highly restrictive and costly modern constraints on waste disposal in volume, for example.
Yet an additional technique employed frequently in petroleum related processes, involves the flooding of ~he tank with water or the liXe, whereupon the liquid effluent is thereafter collected. Whereas in this technique an effort is maid to avoid the aforementioned waste of valuable materials in that valuable hydrocarbons are sought to be reclaimed from the liquid, such material remaining in the solid matter left behind is nevertheless disposed of, which can often include a surprising volume of useful material. Moreover, the aforementioned difficult problem still remained of evacuating the solid material left behind from the sludge which remained in the tank.
Accordingly, a novel method and apparatus was long sought after in the waste removal, treatment, and disposal industry which was safe, efficient, reduced manpower and the volume of solids required for disposal while at the same time providing for recap~ure of valuable materials. These and other objects have been provided in the novel subject invention which overcome the hereinbefore described problems of other techniques as well as others.

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SUMMARY OF THE; INVE,NTION

The invention in one aspect pertains to a method for removing waste material having solid and liquid phase components from a storage container and separating the components, comprising heating a diluent, injecting a first quantity of steam and heated diluent into the container in an amount sufficient to cause a portion of the waste material to flow from the container, - injecting a second quantity of steam and diluent into the flow of waste material in an amount sufficient to maintain flow, separating the liquid and solid phases of the waste material, and collecting volumes of the separated liquid and solid phases of the waste material.

Another aspect of the invention comprehends apparatus for removing waste material having solid and liquid phase components from a storage container and separating the components, comprising means for heating a diluent, means for injecting a first quantity of steam and diluent into the container, means for establishing a flow of waste material from the container, means for injecting a second quantity of steam and diluent into the flow of waste material, means for separating the liquid and solid phases of the waste material, and means for collecting the separate liquid and solid phases.

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More particularly, diluent such as diesel or light cycle oil is pumped from a storage tank to a heating vat where it is steam heated to 20 degrees or less Fare~heit ~han the lowest flash point of material to be removed. The heated diluent is thence delivered by a centrifugal pump to the container to be cleaned. ~lore particularly, the container - in a preferred embodiment has disposed therein a wash manifold preferrably internal of and central to the container whereby the heated diluent is delivered to such manifold and thence in a radially outwards direction from a plurality of ports defined by the manifold against the material within the container.
h plurality of ports such as manways or the li~e disposd in the container about the p~riphery thereof receive steam which is thereby introduced into the container. The combination of the steam and heated diluent acting against the material contained within the container vessel agitate and motivate such material, and in particular render the solids and highly viscous material therein into a pumpable state. The mobile sludge is thence evacuated from the container by means of pumping it thro~gh one of the manways through piping to a heating pot adjacent the container.
In the heating pot additional steam and heated diluent are added to the sludge to maintain its mobility from which it is subsequently transferred to a blending manifold. In the blending manifold, a final quantity of diluent and steam are added in functional relation to the particular waste material characteristics which causes a thorough blending of the steam, diluent, and waste sludge for optimum solids separation. From the manifold~ the sludge is pumped to a separator comprised of a vibrating screen with two sections of screen cloth arranged in s~rial fashion, the first being substantially horizontal .

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and the second being disposed at an incline of about five degrees relative to the first, thereby allowing for maximum retention of sludge on the screen cloths for maximum separation of the liquid phase of the sludge.
Solids separated by the vibrating screen in the separator are deposited into a solids box for subsequent transfer to a disposal site. Remaining liquid material is pumped from the separator to a recovery tank and may ~- contain hydrocarbons including such material from the - solid waste matter originally within the container. These hydrocarbons or other valuable material recovered from the waste matter removed from the container may thence be separated from the material in the recovery tank for recycling and reuse as desired.
The structure of the present invention as well as the features, advantages, benefits, and ohjects thereof over other designs known in the art may be better understood with reference to ~he following detailed description in conjunction with the drawings, wherein:

BRIEF ~ESCRIPTION OF THE ~RAWINGS

Figure 1 is a schematic illustration of the process and apparatus of the present lnvention.

DETAILED DESCRIPTI~N OF THE PREFERRE~-EMB~DIMENT

Referring now to Figure 1 of the accompanying drawings, there will be seen depicted therein a system adapted for practicing the benefits of the present invention as taught herein.
The invention in the form depicted in the aforesaid drawing is for separating and removing hydrocarbons such as oil or the like and solids which are - comingled in a sludge from tanks, ponds, pits, vessels and ~ 3 ~

other containers. I~owever the teachings of the present invention are e~jually applicahle to non petro-chemical applications wherein it is desirable to remove solid waste material and reclaim other chemicals from a storage container and accordingly is not intended to be limited to removal of waste and subsequent separation of merely hydrocarbons from the solids.
In typical applications of the subject invention, - situations are encountered wherein at ambient temperature sludge has solidified (i.e. the temperature is below the pour point) in a container such as a pond, pit, tan~, or other vessel depicted in figure 1 generally as tank 30.
It is accordingly desirable to provide means for evacuating the tank 30 of the sludge, including the solid ; 15 material.
Thus, a storage 12 is provided containing a diluent selected in a manner well known in the art dependent upon the contents of the tank 30 which will break up the material suitably. A representative such material found to be effective in many petrochemical applications is diesel fuel or light crude oil. The diluent is pumped through pipe 14 by means of any ~ appropriate pump 16 through pipe 18 to a heating vat 20 in ; which steam is being inJected ( shown schematically as arrow 22). When the diluent has thereby been heated to the desired temperature, it is thence pumped through pipe 2~ by means of centrifugal pump 26 and from pump 26 through pipe 28 to a manway 32 extending through the wall of tank 30.
Still referring to Figure 1, an internal conduit 48 is shown internally of the tank 30 terminating in a wash manifold 50 which interconnects the pipe 28 and manifold 50. The manifold is basically comprised of a termination wit~ a plurality of apertures whereby when the heated diluent is delivered to the manifold, it is ejected ':

, ~' under pressure through the apertures and against the walls of the tank 30 in various radial directions shown by the arrows 5Z. In a preferred embodiment, the manifold 50 is located generally in the center of the tank 30.
It will be noted in the application depicted in Figure 1 that a plurality of additional manways 34,36, and 38 have been provided. It is contemplated in the present invention that in addition to heated diluent, steam will be injected into the tank 30 for purposes to be hereinafter described. Accordingly, a plurality of distribution headers or spargers ( not shown) are provided, each for a corresponding one of the manways.
The purpose of the spargers is to distribute steam being introducted as shown by arrows 40,42,44, and 46 into the interstices of tank 30 in a dispersal pattern such as that shown by the lines forming a square therein. Although the steam source and conduits to deliver such steam at the locations shown by the arrows has not been depicted, this may be effected in a number of ways well known in the art.
It has been found that due to the combination of heat, diluent, and the mixing effect with the waste ; material in the tank 30, as well as the force being exerted on such material by the steam and diluent, the sludge contained therein, and in particular the solid portions thereof, are rendered into a pumpable state.
Accordingly, a second pump 56 is provided whereby such waste material is evacuated from the tank 30. More particularly, such material is pumped through pipe 54 by means of pump 56 through pipe 58 to a heating pot 60.
The purpose of pot 60 is to maintain the pumpability of the waste material which has exited the tank 30, inasmuch as this material must be transported to a location somewhat removed from the tank for further treatment as will be descrlbed hereinafter. .~ccordinely, : .
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as schematically illustrated by arrows 62 and 64, steam and additional heated diluent, respectively, are introduced in the heating pot 60 to bring the flowing waste material in pipe 58 to ~he desired conditions for optimum solids separation.
From the heating pot 60, the waste material is directed by means of pipe 66 to a blending manifold 68, the purpose of which is to make any final adjustments in temperature of the material by steam addition (shown by arrow 70) and/or heated diluent ( shown by arrow 72) to maintain flow and conditions for optimum solids separation. I~ will be noted that the pot 60 may be located nominally approximately 100 yards from the tank 30 so long as the flow of material in the piping is ~ 15 maintained.
; With further reference to the manifold 68, when it has brought the material to the desired temperature and viscosity, it is thence pumped through pipe 74 to a separator 76. The separator is a vibrating screen ha~ing two sections of screen cloth in series, the first of which is disposed in a generally horizontal position while the following screen is aligned nominally at a 5 degree incline with respect to the first screen. The purpose of this incline is to permit maximum retention of waste material on the screen temporarily to insure that maximum separation of the liquid phase contained therein occurs prior to the solids separated by the screens being deposited through pipe 78 to a solids box 80. The liquid phase, in turn, is pumped by means of pump 8~ throuoh pipe 82 and pipe 86 into a recovered oil tank 88. Solids contained in the box 80 are thence transferred to a disposal site by conventional means. It will be appreciated that the screen mesh size may be determined in - a conventional manner known in the art from laboratory ~ 35 testing of samples of the pumped waste material for :

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particle sizes in order to enhance the solid and liquid separating function of the separator 76. Moreover, as aforesaid, it will be recalled that the temperature of the diluent, and volume thereof, as well as the volume of steam employed introduced at locations proximate to reference numbers 40-46, 50, 62-62, and 70-72, may all be adjusted a~ desired to facilitate maximum pumpability of the waste material as well as separability of the solids - and liquid phases of the material.
Once the tan~ 30 has been substantially evacuated in the manner just described, in some applications it may be desirable for technicians to enter the tank 30 by means of the manways 32-38 and using hoses 52, to further introduce pressurized heated diluent against the remaining sludge to further ensure proper sludge motivation of the remaining material through the pump 56 for subsequent treatment in the manner just described.
Several features of the present invention may now be noted. First, the agitating and motivating effect of the steam and heated diluent makes possible the pumping of solids material contained within the tank 30. This is significant for several reasons. In the prior art it has been convention to simply remove the solids material from within the tank 30 for disposal. However in many processes this solid material contains valuable liquids suitable for recycling which are otherwise lost. By heating the solids wi~hin the tank 30 according to the present method and apparatus, not only are these solids rendered pumpable, simplifying their removal in a more sa~e and efficient manner, but because of this they enter the portion of the system which can recapture these materials from the waste. Moreover, many of these valuable liquid materials are in a solid form in ambient temperature conditions, and by introduction of heat in the diluent and steam, they are brought from a solid phase to 11 3~28~

a liquid phase for recapture and recycling from the tank 88. It has been found in some applications that the volume of solids waste material from box 80 which m~st be disposed of may be reduced by as much as 95% which, in addition to the recapture of hydrocarbons from tank 88, is valuable in itself in terms of cost savings, availability of disposal sites, and the like.
: It is apparent that the present invention is one well adapted to obtain all of the advantages and features hereinabove set fort, together with other ad~antages which ; will become apparent from the description of the apparatus and method. Moreover, the foregoing disclosure and description of the invention in only illustrative and explanatory thereof and admits of various changes in size, shape, and material composition of compnents and details of illustrated construction without depaIting from the scope and spirit thereof.

Claims (20)

1. A method for removing waste material having solid and liquid phase components from a storage container and separating the components, comprising:
heating a diluent;
injecting a first quantity of steam and heated diluent into the container in an amount sufficient to cause a portion of the waste material to flow from the container;
injecting a second quantity of steam and diluent into the flow of waste material in an amount sufficient to maintain flow;
separating the liquid and solid phases of the waste material; and collecting volumes of the separated liquid and solid phases of the waste material.

2. The method of Claim 1 wherein the first quantity of steam and diluent are injected directly against the waste material.

3. The method of Claim 2 further including the step of:
injecting a third quantity of steam and diluent into the flow of waste material injected with the second quantity of steam and diluent.

4. The method of Claim 3 wherein the third quantity of steam and diluent is in an amount functionally related to the waste material in the container to optimize the separating of the liquid and solid phases.

5. The method of Claim 4 wherein the step of separating the liquid and solid phases comprises:
introducing the flow of waste material through a screen disposed at a preselected angle relative to horizontal; and vibrating the screen.

6. The method of Claim 5 wherein the angle is about five degrees, and wherein the step of collecting the liquid and solid phases comprises:
collecting as the liquid phase the material that flows through the screen; and collecting as the solid phase the material that flows off the screen.

7. The method of Claim 6 wherein:
the step of injection of the second quantity of steam and diluent is adjacent the container; and wherein the step of injecting the third quantity of steam and diluent, the separating and collecting of the solid and liquid phases is remotely of the container relative to the step of injecting the second quantity of steam and diluent.

8. The method of Claim 1 wherein the step of injecting a first quantity of heated diluent is at a generally central location within the container.

9. The method of Claim 1 wherein the step of injecting a first quantity of steam is at a plurality of locations disposed radially outwards of and about the central location and within the container.

10. The method of Claim 9 wherein the waste material includes at least one hydrocarbon; and wherein the diluent is heated to a temperature no higher than about twenty degrees Fahrenheit less than the flash point of the hydrocarbon in the diluent having the lowest flash point.

11. Apparatus for removing waste material having solid and liquid phase components from a storage container and separating said components, comprising:
means for heating a diluent;
means for injecting a first quantity of steam and diluent into the container;

means for establishing a flow of waste material from the container;
means for injecting a second quantity of steam and diluent into the flow of waste material;
means for separating the liquid and solid phases of the waste material; and means for collecting the separated liquid and solid phases.

12. The apparatus of Claim 11 further including:
means for injecting a third quantity of steam and diluent into the flow of waste material injected with the second quantity of steam and diluent.

13. The apparatus of Claim 12 wherein the means for separating comprises a plurality of screens.

14. The apparatus of Claim 13 wherein the plurality of screens comprises a first screen disposed in a substantially horizontal position and a second screen disposed in a position inclined with respect to said first screen at a preselected angle.

15. The apparatus of Claim 14 wherein the angle is about five degrees; and wherein the flow of waste material is through the first screen and then onto the second screen.

16. The apparatus of Claim 15 wherein the means for collecting the liquid phase material comprises a container for containing material flowing through the first and second screens; and wherein the means for collecting the solid phase material comprises a solids box for containing material flowing off at least one of the screens.

17. The apparatus of Claim 16 further including:
means for injecting a third quantity of steam and diluent into the flow of waste material disposed between the means for injecting the second quantity of steam and diluent and the means for separating.

18. The apparatus of Claim 17 wherein the means for injecting the first quantity of steam and diluent comprises:
a wash manifold means disposed centrally within the container for injecting the diluent; and a plurality of spargers disposed radially outwards of and about the wash manifold and within the container.

19. The apparatus of Claim 18 wherein:
the means for injecting the second quantity comprises a heating pot;
the means for injecting the third quantity comprises a blending manifold and wherein the apparatus further includes:
piping means interconnecting the container to the heating pot, the heating pot to the blending manifold, and the manifold to the means for separating in order to establish fluid communication and flow of the waste material from the container, through the heating pot, and thence through the manifold to the separator.

20. The apparatus of Claim 19 wherein the means for heating the diluent comprises a heating vat containing the diluent heated within the vat by steam to a temperature of about 20 degrees Fahrenheit below the flash point of the diluent and wherein the means for injecting the heated diluent into the container comprises the wash manifold and a pipe providing fluid intercommunication between the vat and the manifold.