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Патент USA US3051668

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Aug. 28, 1962
3,051,649
T. W. LEGATSKI
PURIFICATION OF‘ LIQUEFIED PETROLEUM GASES
Filed Oct. 5, 1959
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INVENTOR.
T.W. LEGATSKI
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‘ Patented Aug. 28, 1962
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as the lique?ed petroleum gas is taken out of storage for
3,051,649
"
PURIFICATION OF LIQUEFED PETROLEUM
GASES
'
..
Theodore W. Legatski, Bartlesville, Okla, assignor t0
Phillips Petroleum Company, a corporation of Dela- '
Ware
Filed Oct. 5, 1959, Ser. No. 844,348
9 Claims. (Cl. 208--299)
distribution. It is another object of this invention to
provide a start-up procedure for fresh adsorbent beds
whereby the odorant level of the LPG passed to a place of
utilization is maintained at the proper level during the
start-up of the operation.
Other aspects, objects, as Well as the several advantages
of this invention, are apparent from a study of this dis
closure, the drawing and the appended claims.
This invention relates to the puri?cation of lique?ed
In accordance with the present invention, a method is
petroleum gases. In accordance with one aspect, this in l0 provided for the removal of heavy contaminating ma
vention relates to the-puri?cation of lique?ed petroleum
’ teri'als, such as heavy oils, greases, polymers, and the like,
gases (LPG) wherein heavy contaminating materials, such
from lique?ed petroleum gases'(LPG) which comprises
‘as heavy oils, greases, polymers, and the like contained
passing the LPG in liquid phase through a bed of activated
therein, are removed therefrom by contacting said LPG 15 charcoal, silica gel or similar adsorbent material which
with a solid adsorbent material that selectively absorbs
selectively adsorbs the heavy contaminating materials in
said contaminating materials in the presence of LPG. In
the presence of LPG.
'
accordance with another aspect, this invention relates to a
Also, in accordance with the present invention, a_ method
start-up procedure for placing fresh adsorbent beds into
is provided for starting-up or placing fresh adsorbent beds
service which are utilized for selectively adsorbing con 20 into service utilized for selectively adsorbing heavy con
taminating materials from odorized LPG without lowering
taminating materials from odorized LPG without lowering
the odorant concentration of said LPG passed to a place '
of utilization which comprises cycling a stream of odorized
LPG through a new bed of adsorbent until said adsorbent
is saturated with odorant, and then placing said bed satu 25
the odorant concentration of said LPG passed to a place of
contaminants from LPG.
selective adsorption of heavy contaminating materials
rated with odorant into adsorption service for removing
,
utilization which comprises cycling a stream of odorized
LPG through a new bed of adsorbent material until said
adsorbent is saturated with odorant, and then placing said
bed of adsorbent saturated with odorant into service for
The problem of heavyoils, greases, polymers, and other
present in said odorized LPG. The selective adsorbent
liquid materials contained in lique?ed petroleum gases has
materials that can be utilized in the practice of the present
been with the industry since its inception. These oils 30 invention preferably comprise activated charcoal, silica
accumulate in containers from which the gas is taken as a
gel, activated alumina, and similar adsorbent materials
vapor, ‘and consequently on reuse will build up to undesir
which selectively adsorb the heavy contaminating materials
able quantities in these containers. When taken from the
present in the LPG treated. These adsorbent materials
containers as a liquid, these heavy contaminating materials,
may be activated before use by calcining at temperatures
pass into the utilization system, and eventually clog regu 35 of 500 to 1,500° F. The granular adsorbent materials are
' lators, jets, carburetors, and burners, and may accumulate , used in suitable particle size for permitting ?uid ?ow With
in low points to discharge as slugs of heavy material. In
out excessive pressure drop even in relatively deep beds
accordance with the present invention, method and appa
and at ?ow rates consistent with e?icient adsorption.
ratus are provided for the removal of these contaminating
Ordinarily, the size of the adsorbent particles used in the
materials from lique?ed petroleum gases prior to ?nal 40 present invention will be in the range of 4 to 100 mesh U.S.
utilization, thus avoiding any such problems during utiliza
Standard and preferably from 8 to 50 mesh. From the
tion.
'
standpoint of adsorption rate, the ?ner particles are better,
LP gases are unique in that they clean up every surface
but the larger particles are preferable from the standpoint
with which they come in contact, all to the detriment of
of pressure drop. Thus, the actual size employed becomes
LP gas quality. The heaviest contaminants are lube oils, 45 a matter of economics.
stop-cock greases, polymers formed from LP gas ole?ns,
The temperature or" operation of the adsorption zone is
etc. One of the problems is to manufacture, store, trans
ordinarily the ambient temperature of the installation. To
port, ‘and handle the product numerous times before it
provide the greatest adsorptive capacity during adSOrptiOn,
reaches the customer and still keep it free of contaminants.
the temperature is generally kept low, preferably below
Each step in handling is a potential source of contaminants. 50 about 150° F. The operating pressure employed in the
As a. result, contacting with adsorbent charcoal, etc., has
adsorption zone is at least sufficient to maintain liquid
application as a ?nal treatment before passing the LP
phase conditions. Pressures above that necessary to main
gas to the customer. Also, subsequent to the puri?cation,
tain liquid phase has no bene?cial re?ect on the process but,
clean apparatus should be employed to avoid contamina
of course, can be used if some reason should arise in a
tion of the LP gas before it reaches the customer.
55 speci?c installation. Liquid flow rates through the adsorp
In accordance with the present invention, I have found
tion beds will generally range from 0.05 to 5 liquid volumes
that heavy contaminating materials, such as heavy oils,
greases, polymers and the like contained in lique?ed
an hour, preferably 0.1 to 2 volumes per hour.
The conditions of pressure, temperature, etc. employed
petroleum gases can be conveniently removed from said
during regeneration of the adsorbents will depend upon
gases by contacting with a solid adsorbent, such as acti 60 the adsorbent in service. The metal oxide adsorbent, such
vated charcoal, silica gel, or similar adsorbent, which selec
as silica gel, activated alumina and bauxite, can be regena
tively adsorbs the heavy materials in the presence of LPG. >
erated
by oxidation of the accumulated heavy contaminat
Also, a start-up procedure is provided for placing new
ing materials on the adsorbent with air or diluted air at
beds of adsorbent into service without reducing the odorant
750° F. to 1,200°-‘F. The clean adsorbent is then cooled
concentration of LPG passed to a place of utilization.
65 and used in another cycle. Also, the heavy contaminating
It is an object of this invention to purify lique?ed
materials adsorbed on the adsorbent can be removed by
petroleum gases. It is another object of this invention to
washing o? these materials with a volatile and readily
provide a method for the puri?cation of lique?ed petrole
um gases by removing contaminants contained therein.
adsorbable material, such as benzene, toluene, methyl or
It is another object of this invention to provide a method 70 ethyl alcohol, and the like, and then removing the adsorbed
‘ for the puri?cation of lique?ed petroleum gases for the
volatile wash liquid by heating to an elevated temperature,
removal of heavy contaminating materials present therein
such as 600 to 1,200° F. in a stream of inert gas, the clean
.
Mme '
.7 adsorbent then being 'coolee and used in the’ new adsorp-p
tion cycle.
‘Activated charcoal or icarboncan' beregenerated [after
' adsorbent with an added quantity of equilibrating odorant
' without actually affecting the odorant content of the LPG
stored in, zone. 14}. This may be accomplished 'by open
ing valves 11A, 13A and 21A and closing all other valves
use by the above methods also,rbut the oxidation withair
is not desirable "due to the oxidationiof the carbon ad 5 in the system; ‘Pump ,12;i-s_ thenrnsed to pump asmall
sorbentand rapid lossof this material.’ Therefore, .itrisl
preferable to steam thewca'nbon adsorbent at conventional
temperatures, such as 900 to 1,5()O° ,_' F.,to remove the
‘amount ,of’LPG through lines 111 ‘and l13‘jlhIOl1Vgll'adSOl'b
- ent zone 14 andllines‘ 15 1 and-21 to ‘surge tank 23. When
I? surge tank'ZShas ?lled to’ the desired level, valve 11A
is closed and valve 2'4A.-is“i~opened. Thus, a recirculating
stream of LPG is established which continuously passes,
V adsorbed heavy. contaminating materials. ‘The clean car-l
. .710.
bon is then cooledrand reused in'the‘ adsorptionv cycle. 7
In order that this invention may be more, clearly under-_ , over the adsorbentlin zone (14,‘ and equilibrating odorant
maybe ‘added to this recirculating stream through line 22.
stood, reference will be made to the‘accompanying draw
ing which diagrammatically illustrates a flow sheet of one .7 Su?icient odorantiis ‘added by this means to satisfy the
, adsorbent inzone- 14"s'o'that the recirculating stream'will
speci?c embodiment of the present invention.
7 ’
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' Referring now to the drawing, a lique?ed petroleum gas 15 contain
the desired level of odorant; QAt this time, recir
culrationrmay be stoppedand the system operated as pre»
containing heavy contaminating materials, such as'heavy
oils, greases, polymers and. the 1ike,‘is stored in storage . Vviou-sly desoribedwith passage of, LPG'to the loading rack
zone 10.
Storage zone :10 can comprise such means, ‘as
or dispensing systemf;
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'
Although the invention has been described above pril' V
large re?nery tanks, bulk station storage tanks, or under
ground storage caverns, commonly ‘employed at terminals 20 marilyntilizing‘ only one adsorbent ?lter bed zone 14, it
should be understood by. those skilled in the ant that any
7 or other locations requiring'largei-volumes of storage ca
number of beds desired can be advantageously employed.
pacity. The lique?ed petroleum gas at ambient ‘tempera
In a speci?c operatiomtwo adsorbent zones are employed,
ture, which can vary appreciably depending upon whether
one beingin' adsorption service while the other zone is
storage vzone :10is above or below-ground, is, removed
‘
from the storage, zone by way ofconduitl‘l and pressured 25 being. regenerated and saturated with odorant.
A'test of this invention was carried out when‘ dii?culty
was encountered with heavy residuesgshowiug up in LP
gas removed. fromia rented underground storage cavern.
nated LPG is passed as a liquid through adsorbent bed in
.TheLP gas removedifrom this cavern was found to con
?lter bed ‘14 wherein the heavy contaminating materials
are selectively adsorbed on the adsorbent which canbe 30; tain sl'l?icient heavy contaminants that utilization was.
V .by'pump 11-2 through conduit v13 and introduced to an’
7 upper portion of'adsorbent ?lter bed :14. The contami
causing consumers di?iculty. A vbed ofcharcoal was in
stalledat the storage point-and‘ the liquidremoved from
the cavern was passed over the charcoal adsorbent prior to
activated charcoal, silica :gel or other selective adsorbent,
materials. The puri?ed lique?ed petroleum gas is removed
from ?lterbed zone 14 through conduit'VIS'and ispassed
by way of conduit 16 to a loading rack or- other dispensing
distrtibuti-on.~
system not shown whereby the ‘puri?ed LPG'is passed to a, 35
place of utilizatio
.
I
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a
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Afterthe installation of the charcoalbed, no further
dif?culty with these heavy residues was encountered.
e
‘Reasonable variation and modi?cation are possible with
in the scope of the foregoing disclosure, drawing and
the appended claimseto the invention, the essence of which
difficult to prevent passing from the ‘bed, along with the
liquid e?luent, particularly immediately following recharg: 40 is that heavy contaminating materials, such as heavy oils,
As is well known, adsorbents, » such; as charcoal ‘and
. silica-gel, have'a small content of ?ne material which is
ing the ?lter zone with a'tresh batch of adsorbent. At
greases; polymers arid-the like, contained in lique?ed pe
such times as dif?culty is encountered with ?nes contami
nating the e?luent stream, valve VISA may be closed and
troleum gases are selectively removeditherefrom by con
tacting said LPG in the liquid phaserwith a solid adsorbent .
that selectively adsorbs said contaminating materials in
valves 18A and 20A opened,.the liquid e?luent thus being
carried ‘from line 15 through line 18 to'a ?ne solids re 45 the presence ‘of LPG and, further, 'a start-up procedure is
' . moval zone which may be a ?lter packed with felt,rcotton 7 provided for placing ?resh adsorbent .beds into service
which are utilized ‘for selectivelyadsorbing,contaminants
Waste or other suitable ?ltering medium.v The ?ltered
?‘om odorized vLPG Without lowering the odorant concen
tration of said LPG passed to a place of utilization which
, ‘In many installationsethe- LPG is cdorized in'storage 50
V comprises cycling a stream of odonizedi LPG through a
new bed of adsorbent until said adsorbent is saturated with
zone-10, and it is necessary that the odorant be present in
odorant, and then placing said bed saturated with odorant
the treated gas. Any odorant Wellhnown in the art ‘for
into selective adsorption service.
' '
'
odorizing LPG can be employedin the present invention.
material is then removed from zone 19 throughjline 20 to
line 16 to utilization as previously’ described, '
~
' ‘Suitable odorants include .the mercaptans, especially
I claim:
methyl and ethyl mercaptan. < As charcoal and silica gel 55
arehighly selective iforltheeodorantsemployed in LPG,
’
'
‘
'
1. A method for purifying ‘an odorized' lique?ed petro- -
' ileum gas containing heavycontaminating materials com
prising heavy'oils, ‘greases, polymers’, and r-the'like, before
'it is desirable to. employ astart-up procedure for freshly‘
chargedi?lter zones ‘wherein the adsorbent'pis brought to _ passing said lique?ed gas to a "place of utilization which
’ equilibrium iprior torpassage of the ?lter zone ei?nent to 60 comprises removing said’odoriz'ed lique?ed ‘gas ‘from stor
. utilization through line r16.‘v One method of accomplishing
age, passing same to anadsorp'tion zone containing a ?xed
this equilibration is by opening valves 17A, 13A and 111A " bed of aysolid adsorbent ,material, passingsaid lique?ed ,
and closing all-other valves in the system. ,Stored LPG
.gas in the liquid phase through‘ saidbedfto selectively re
is‘then pumped throughlines 1'1»and'13 through ?lter zone . movesaid contaminating materialstherefrom and to ob
‘I4 vand returned to, the storage 'zoiielthrough lines 17 until '
such time, as the ?lter ‘zone e?iuent contains thelproper '
65 tainisaid lique?ed‘gas substantially, free of said contami7 L
' natin-g'materials. Passing saidrmri?ed'lique?ed gas through
level of odorant,‘which indicates that the adsorbent within
a ?ne solids ?ltrationzone to. remove entrained ?ne ad
the'?lter zone has become saturated. .The adsorbent will,
sorbent entrained therein, andpassing" said lique?ed gas.
let course, hold asrn'all amount of the total odorant con- 7 ' to said place of utilizationas ‘a product of themethod.
tent of the LPGand thus must lower the overall content
' of the material in ‘storage.’ ‘However, in the ordinary in '70’
stall-atiom'the; storage'zone
be quiterlarige and the
2. A‘method'according to claim‘ 1. wherein a ‘fresh bed
of adsorbent‘ before being placed into service for adsorp—
' loss of odorant to the adsorbent willbeiso small as to be
immeasurable. In most instances; the above start-up pro~.
, tion of said contaminating materials from said lique?ed
‘gas is‘ treated'with a stream of ,odorized ?uid cycled
cedure will be'quite satisfactoryra'nd certainly quite simple.
- " through said adsorbent bed until said bed'is saturated with
. Inlsome. instances, it maybe desirable to saturate fresh
75'saidodorant.
’
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3,051,649
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3. A method according to claim 2 wherein ‘said odor
ized ?uid is odorized lique?ed petroleum gas.
4. A method for preheating a bed of fresh adsorbent
before said bed is placed into adsorption service to selec
tively adsorb contaminants from ‘an odorized lique?ed
6
8. A method for removing contaminants from-an odor
ized, lique?ed petroleum gas which comprises removing a
liquid stream of said lique?ed petroleum gas containing
said contaminants and an odorant from a storage zone,
passing said stream under liquid phase conditions through
‘ petroleum gas which comprises cycling a ?uid stream of
an adsorption zone containing a ?xed bed of a solid ad- ‘
odorized material through said fresh bed of adsorbent
1 until said bed of adsorbent is saturatedwith odorant,
sorbent that ‘selectively adsorbs said contaminants in the
presence of said lique?ed petroleum gas, thereby obtain
and then placing said'bed into adsorption service.
5. A method according to claim 4 wherein said cycled
ing a lique?ed petroleum gas stream as a product sub
stantially free of said contaminants, continuing said ad
sorption until said'adsorbent has become spent, regenerat~
ing vsaid adsorbent by desorbing said adsorbed 'con
taminants therefrom, ‘odorizing said regenerated adsorbent
material. is odorized lique?ed petroleum gas.
_
6. A method for ‘ removing contaminating materials
from a lique?ed petroleum gas containing same which
comprises removing odorized lique?ed petroleum gas con-V
by cycling a stream of said odorized lique?ed petroleum
taining said contaminants from a storage zone ‘for said '15 gas through said bed until said bed is saturated with
lique?ed petroleum-gas, passing said lique?edtpetroleum
odorant, and'then placing said odorized bed of adsorbent
back intoselective adsorption service, thereby avoiding
gas at ambient temperature to an‘ adsorption zone con
taining at least‘ two units wherein at least one unit is on
lowering, of the odorant concentration of said lique?ed
cycle, each of said units containing a ?xed 'bed of solid ' petroleum gas passed to a place of utilization after ad
7 adsorption cycle and at least .one unit on regeneration
adsorbent that selectively’ removes said contaminants in 20 ‘sorption of contaminants when a new or fresh bed of
adsorbent is put into service.
the presence of liquefied petroleum gas, said bed of ad-*
9. YA method according to claim 8 wherein said cycled
sorbent in each of said units having been contacted with
' stream of odorized lique?ed petroleum gas is removed
from said ‘storage zone, passed through said bed of adsorbent and then returned to said storage zone.
a cycled o'dorized stream until saturated with odorant
before being place into selective adsorption service, pass "25-
ing said contaminated lique?ed petroleum gas in the liquid
phase through one of said units in adsorption service to
References Cited in the ?le of this patent
selectively remove said contaminants, passing decon
taminated lique?ed petroleum gas through a ?lter ‘zone
UNITED STATES PATENTS
to remove entrained ?nes from said‘ lique?ed petroleum
Babcock _____________ __ July 29, 1941
gas, and passing said ?ltered lique?ed petroleum gas 30 2,250,925
2,530,300
Hirschler ___________ __ Nov. 14, 1950
substantially free of contaminants and entrained adsorbent
?nes to a place of utilization. I
2,727,367
'
7. A method according to claim 6 wherein said cycled
odorized stream is odorized lique?ed petroleum gas.
35
2,904,507
2,921,026,
McKinney _________ __'__ Dec. 20,'l955
Jahnig- ______________ __ Sept. 15, 1959‘
Fleck'et a1. _, ______ __Y__ Jan. 12,1960
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