Патент USA US2404061код для вставки
Patented July 16, 1946 2,404,061 UNITED STATES._.,..'.UPATEN.T orrlcs ‘ '_'2,404,061 METHOD iron, FILTERING Julian P. Hamilton, Pelly, and Charles F. Jones, Goose Creek, Tex., assignors to Standard Oil Development Company, a corporation of Dela .Ware No Drawing. Application October 19,1943, Serial No. 506,898 5 Claims. (01. aloe-201) 2' . : - "The present‘ invention is directed to a method for ?ltering in which a sheet ?ltering surface is be’ absolutely inert but may contain ‘a’ minor precoated with a ?ltering aid before the ?ltering rials. operation is begun. supplementing the preceding postulate, is that amount of oxygen ‘which oxidizes these'mate I The present'invention is particularly applica ble to the ?ltration of asphaltic or gummy ma 5 the tarry, or resinous materials are relatively ?uid at the temperatures of the order of ‘600° 'F. em terials by-means of rotary ?lters.- An example of such an operation, is the ?ltration of' cracked tars- in petroleum re?neries through a rotating ?ltering element with the ?ltering element pro vided with a'precoatingo'f ?ltering aid, such as ployedfor the ?ltering step but are substantially solid at the temperatures ‘of‘the order of‘_250° F. commonlyused for washing and discharging the 9 ?lter; iltwillibe understood that-these postulates explaining the formation of the (residual heel in the ?lterduring conventional ?ltering operations diatomaceous earth, before the tar is passed through the ?lter. ' ' ' 'Anothelr'explanation, Or an explanation are suggested only byway “of explanation and are in, no wise intended to‘ limit the, present, inven . It has been known to the art to ?lter tarry or resinous material, such ‘as. hot. cracking coal 15 tars, througharotary' ?lter. _ In this operation tion. . I . , ._ v f . We have .now discovered that a greatly in. it has been ‘customary 'to deposit preliminarily upon the ?lter screen adiatomaceaus'earth pre creased ?ltering capacity may be obtained when ?ltering cracked tars and other tarry or resinous .coat with a thickness of the order of three inches. material. ’ In accordance with our discovery, As the ?lter, surface revolved the precoat was the ?ltering operation is terminated before the resinous or tarry materials being separated from the filtrate penetrate through the precoat torthe ?lter screen. The charge remaining within the ?lter shell ‘is discharged therefrom, being @re placed, for example, with gas oil and the portion of the precoat into which the resinous ‘and tarry -materials have penetrated is trimmed __0f_fiby. the trimmed o? at a rate of from,0.001 to 0.003 inch per revolution of the ?lter drum until the pre coat remaining was no more, than one-quarter of an inch thick. It has then been customary to displace the hot cracking tar with a cooler ,25 liquid to coolthe‘?lter shell, as m‘uchyof this cooler liquid being drawn through the ?lter as possible and the remainder pumpedout. The ?lter screen and remaining precoat was then sprayed vwith gas oll?to remove asmuch of the precoat and depositedgsolids as possible. In such ?lter knife or‘ doctor. ~ After the removal-'of'the plugged portion of the precoat-the.remaindercf 30 .the‘precoat, free from binding and plugging ma terials, is either. removed entirely by washing or, a procedure, however, substantial amounts of re alternatively, it is left on‘the ?lter ‘screen as a sidual materials from the tar penetratethrough base and anew layer of precoat deposited on the -‘ the precoat to the screen and theresidual heel 35 ?lter and the ?ltering cycle repeated. is plugged and bound to the ?lter screen by these tarry or resinous materials. This contaminated ‘I The improvement in the capacity of the ?lter by the employment of the present invention is indicated in the following table, in which the heel cannot be removed from‘ the ?lter by wash ing with‘ gas oil or a similar solvent and,‘ ac conventional procedure is shown under the head ing “Old operation” with runs 1, 2 and ‘3' and the employment of the present invention shown under the'heading “Newv operation” with runs use of steel brushes. In such operations the time 4, 5 and 6. Whereas, the ?ltering time per, cycle required to openlthe ?lter and clean the screen under the old operation is somewhat longer than was large withrespe‘ct to the total ?ltering cycle.‘ The exact nature of the tarry or resinous ‘ma 45 under the new operation, the turnaround time has terials which penetrate below the surface of the ..been so reduced under the new operation that cordingly, it’has been necessary to open the ?lter and remove the remainder of the precoat and 40 the tarry materials plugging the" screen, by the nrecoat and ‘act to plug and bind the residual heel to the ?lter screen is not known. As a pos the total time per cycle is much less under the new operation and gives a greatly increased ca tulate, it is suggested ‘that the hot cracking coal “pacity factor. The three runs carried out un— '_ ?ltered include viscousor resinous liquids which ' penetrate into the precoat and forma coating on. the surfaces of the particlescomprising the pre the new operation had an-average‘cycle time of‘ der the old operating conditions had an aver tens or viscosity breaker bottoms conventionally 50 _' age oycle time of 85 hours, while the runs under r 53.7 hours and the capacity factor of the ?lter was increased from 62.1 per cent under the old .rcome coked atthe vhigh temperature of ?ltraa 55. _ operation to 81.7 per cent under the new opera _ coat.‘ These tarry or resinous materials may be _ tion, orthe gas employed-"in the ?lter-may-not . tion. 2,404,061 Ta'bZeI Old operation, average New operation, average Run No. l ' ' . 2 51.0 52.8 50.0 2.5 4.5 3.5 2.0 2.5 1.0 2.5 2.0 Turnaroundtime ______________________ __d0____ 15.0 6.5 57-0 26.1 2.07 3.2 0.7 1.9 Cycletime ______________________ _-do_.__ 74,8 66.5 114-0 350 56.0 49.7 65.7 53.7 wepercent__ 72.9 -79.8 Cycle time """""""""" " ' 44.8 62,1 75.8 ‘83.4 _ Capacity factor: 4.0 3.6 3.0 6 53.0 _ ' 5 2.0 Coolingtime... 3.5 4 54.5 giftiii?gé?iiIII: 3.3 3 41.5 48.5 87.1 3.3 46.7 1.8 81.7 While we have disclosed speci?c examples of the application of the present invention to the ?ltration of viscosity breaker bottoms and other A slurry of diatomaceous earth in gas 011 was viscous cracked tars consisting of asphaltic ma forced into the ?lter shell and gas oil passed through the ?lter medium until a diatomaceous terial, it is to be understood that the invention is earth precoating three inches thick formed on not limited to the ?ltration of this speci?c ma the ?lter screen. The slurry was then displaced terial but may be applied generally to the treat from the ?lter shell and viscosity breaker bot ment of materials, having incorporated therein toms at 600° F. passed through the ?lter while tarry or resinous matter capable of penetrat the screen was rotated at a uniform rate and the ing a precoat to aconsiderable depth and which precoat trimmed off at the rate of 0.001 to 01103 25 may combine with the solid particles of the pre inch per revolution of the ?lter until a layer of coat during the ?ltering operations and act to precoat one-quarter inch thick remained. The plug the precoat and bind it to the ?lter screen. ?lter shell was then cooled by replacing the vis It will also be understood that the method of the cosity breaker bottoms with cracked tar at 250° present invention is by no means limited to the F. This tar was drawn through the ?lter in a 30 speci?c temperatures given in the examples ‘but normal manner and the residual tar in the ?lter thatv it may be practiced over a wide range of shell then pumped out. The ?lter screen was temperatures. then sprayed with gas oil to remove as much of Having fully described the present invention, the precoat as possible and the ?lter then opened and the ?lter screen scrubbed by hand with steel 35 what we desire to claim is: 1. A method for?ltering wherein a viscous liq, brushes. After this operation the screen was uicl containing solids and substantial amounts of closed and the cycle was repeated. Runs 1, 2 and 3 in the above table were conducted as follows: . tarry materials capable of penetrating through Example 2.-New operations a substantial thickness of precoat is passed The precoat was formed on the ?lter screen in 40 through a moving ?lter screen provided with a the same manner as in Example 1. The viscosity breaker bottoms at 600° F. were then passed through the ?lter medium while the precoat was progressively removed by the ?lter knife until about three-quarters of an inch of the precoat 45 substantial thickness of precoat, comprising the steps of continuously removing a thin layer of precoat and deposited solids from the ?ltering element while the w‘scous liquid is being passed through the element, terminating the ?ltration remained on the ?lter. Cracked tar at 250° F. of viscous liquid while a substantial thickness of was then charged to the ?lter to cool it down the precoat adjacent the screen is uncontami with the tar being drawn through the ?lter but nated with the tarry materials, removing alayer no precoat being removed during the cooling op of the remaining precoat, having a thickness of eration. The residual tar was then pumped out 50 the order of 1/2 inch and including at least that from the bottom of the ?lter shell and the knife portion of the remaining precoat contaminated blades advanced to remove approximately one by the tarry materials, subsequently providing the half inch thickness of the precoat, leaving a layer ?lter screen with the precoat layer of substantial only about one-fourth inch thickness ofthe pre thickness and repeating the cycle. coat on the ?lter shell. A slurry of diatomaceous 55 2. A method for ?ltering comprising the steps earth in gas oil was then pumped into the ?lter of depositing a relatively thick layer of ?lter aid shell and new precoat deposited directly upon on a rotating ?ltering element, passing a viscous the one-fourth inch layer of precoat to build up tar containing solids and substantial amounts of another precoat three inches in thickness and the ?ltering cycle was then repeated. The char 60 tarry materials capable of penetrating through a substantial depth of precoat therethrough and acteristics of the viscosity breaker bottoms, continuously removing a thin layer of precoat cracking coal tar and gas oil passed to the ?lter and deposited solids from the moving ?ltering in the above examples are as follows: element to provide a freshly exposed layer of pre Table II coat with every revolution of the ?lter, termi 65 Viscosity- - breaker Ora-‘3km bottoms Gravity, "APL _ 7. _____ ___ _______ ._ Viscosity: coal tar 12.0 11. 0 Gas oil 32.0 ~ SSF at 122° F_ SU at 100° F“ Sediment: By extraction, wt. percent_.__. By hot ?ltration, wt. percent. 0. 25 1.0 0. 05 ________ __ 0.06 ________ __ nating ?ltration of the tar while the remaining precoat layer is of substantial thickness and be— fore the tarry materials deposited thereon have penetrated that portion of the precoat adjacent the ?lter screen, removing the tar from contact 70 with the ?ltering element, removing a layer of the remaining precoat having a. thickness of the order of 11; inch and including at least the con taminated portions of the precoat remaining on the screen, providing a new precoat layer of ap 75 proximately the same thickness of the layer‘at 5 2,404,001 the beginning of the cycle and repeating the penetrating cycle. 3. A process in accordance with claim 2 in which a thin layer of uncontaminated precoat of 600° F. in contact with said ?ltering element ' and ?ltering tar from said pool through said ?l tering element and continuously removing a thin layer of the precoat and deposited solids from said ?tlering element while the viscous tar is being ?ltered, terminating the ?ltration of said precoat layer. tar when the precoat layer has been reduced to 4. A method in accordance with claim 2 in a thickness of the order of 3/; inch, replacing which all of the precoat layer is removed from the tar in the pool with low viscosity tar at about the ?lter screen, and the new precoat layer is 10 250° F. to cool the ?lter, removing the low vis built up directly on the ?lter screen. cosity tar from said pool, removing a layer of 5. A method for ?ltering comprising the steps said precoat having a thickness of the order of of depositing a layer of ?lter aid on a rotating 1/2 inch and including a contaminated portion, ?ltering element to a thickness of approximately subsequently depositing a new layer of precoat 3 inches, forming a pool of highly viscous tar 15 on said ?ltering element to a depth of approxi is retained on the ?lter screen and additional precoat is deposited thereon to build up the new containing solids and asphaltic material capable of penetrating a substantial depth into a, layer of precoat and at a temperature of the order mately 3 inches and repeating the cycle. JULIAN P. HAMILTON. CHARLES F. JONES.