U.S. patent application number 11/048265 was filed with the patent office on 2005-09-01 for system for removal of methanol from crude biodiesel fuel.
Invention is credited to Lastella, Joseph P..
Application Number | 20050188607 11/048265 |
Document ID | / |
Family ID | 34889762 |
Filed Date | 2005-09-01 |
United States Patent
Application |
20050188607 |
Kind Code |
A1 |
Lastella, Joseph P. |
September 1, 2005 |
System for removal of methanol from crude biodiesel fuel
Abstract
A method of removing methanol and other substances from crude
biodiesel, includes mixing a silicone based adsorbent with the
crude biodiesel. The silicone based absorbent may be a magnesium
silicate adsorbent with a formula of 2 MgO:65:02 nH.sub.2O. A plant
for making biodiesel fuel has a first section for making crude
biodiesel fuel methanol therein, and a second section for removing
the methanol from the crude biodiesel, the second section has a
tank for mixing the crude biodiesel and the silicone based
adsorbent for the methanol, and a filter for filtering the
adsorbent mixed with methanol from the crude biodiesel thereby
producing biodiesel.
Inventors: |
Lastella, Joseph P.;
(Bakersfield, CA) |
Correspondence
Address: |
LAW OFFICES OF DAVID L. HOFFMAN
27023 MCBEAN PKWY
SUITE 422
VALENCIA
CA
91355
US
|
Family ID: |
34889762 |
Appl. No.: |
11/048265 |
Filed: |
January 31, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60540751 |
Jan 31, 2004 |
|
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Current U.S.
Class: |
44/605 |
Current CPC
Class: |
Y02E 50/10 20130101;
C10G 2400/04 20130101; C10L 1/026 20130101; Y02E 50/13
20130101 |
Class at
Publication: |
044/605 |
International
Class: |
C10L 005/00 |
Claims
What is claimed is:
1. A method of removing methanol and other substances from crude
boidiesel, the method including a step of mixing the crude
biodiesel with a silicone based adsorbent.
2. The method of claim 1, wherein the silicone based absorbent
comprises a magnesium silicate adsorbent.
3. The method of claim 2, wherein the magnesium silicate adsorbent
has the formula 2 MgO:65:02 nH.sub.2O.
4. The method of claim 1, further comprising a step of filtering
the crude biodiesel and adsorbent to separate the biodiesel from
the adsorbent mixed with methanol and other substances.
5. The method of claim 1, wherein the amount of adsorbent mixed
with the crude biodiesel is no more than one weight percent.
6. The method of claim 1, wherein the amount of adsorbent mixed
with the crude biodiesel is 0.4 to 0.8 weight percent.
7. The method of claim 1, further comprising a step of adding water
to the crude biodiesel in addition to the adsorbent.
8. The method of claim 7, wherein the amount of water is about one
weight percent.
9. A method of forming crude biodiesel by a process including the
steps of adding methanol to a reaction vessel where esterification
takes place, and heating the reaction vessel to at least about
140.degree. F., sealing the top of the vessel, placing a condensing
coil outside of the vessel and in communication with an upper
portion of the vessel containing methanol vapor, for condensing
methanol which escapes from the vessel in the condensing coil.
10. The method of claim 9, wherein a negative pressure is applied
to the coil for creating a negative pressure at the top of the
vessel, and air is allowed into the top of the vessel.
11. The method of claim 7, wherein the amount of adsorbent is less
than 0.4 weight percent.
12. The method of claim 1, wherein the crude biodiesel is formed by
a continuous flow process.
13. The method of claim 1, wherein the crude biodiesel is formed by
a batch process.
14. The method of claim 1, wherein there is a step of heating the
crude biodiesel before mixing in the adsorbent to demethalate the
crude biodiesel.
15. The method of claim 1, wherein in the step of removing
methanol, glycerin and one of potassium and sodium hydroxide are
removed.
16. A plant for making biodiesel fuel, the plant comprising: a
first section for making crude biodiesel fuel having methanol
therein, and a second section for removing the methanol from the
crude biodiesel, the second section comprising a tank for mixing
the crude biodiesel and a silicone based adsorbent for the
methanol, and a filter for filtering the adsorbent mixed with
methanol from the crude biodiesel thereby producing purer
biodiesel.
17. The plant of claim 16, wherein there is a means for heating the
crude biodiesel to dementhalate it prior to the tank.
18. The plant of claim 17, wherein the means for dementhalating
comprises, a chamber disposed at an angle, the chamber comprising
means for heating the crude biodiesel fuel proximate a low end of
the chamber to create methanol vapor, and having means for
condensing methanol vapor, and means for removing the biodiesel,
both proximate a high end of the chamber.
19. The plant of claim 18, further comprising means for removing
glycerin proximate a low end of the chamber.
20. The plant of claim 18, further comprising means for
recirculating biodiesel from above a low end of the chamber back to
the low end of the chamber to the means for heating.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority under 35 U.S.C. .sctn.
119(e) from U.S. Provisional Patent Application No. 60/540,751
filed Jan. 31, 2004, incorporated by reference herein.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a system for removal of
methanol and other substances from crude biodiesel fuel.
SUMMARY OF THE INVENTION
[0003] In a process of making biodiesel fuel from soy bean oil,
yellow grease or other raw material containing fatty acid esters,
generally the raw material is processed with about ten percent
methanol and about one percent potassium hydroxide or sodium
hydroxide.
[0004] In U.S. patent application Ser. No. 10/235,065, filed Sep.
4, 2002, in the name of the present inventor (referred to herein as
"Continuous Flow Application"), and incorporated by reference
herein, there is disclosed a continuous flow process for forming
biodiesel from yellow grease, vegetable oil, soy bean oil, or other
raw material having fatty acid esters. The Continuous Flow
Application also contains a description of the conventional batch
process.
[0005] In either the continuous or batch process, or any other
process for making biodiesel, the raw material is processed with
methanol and preferably with a catalyst such as sulfuric acid
(H.sub.2S) in a reaction vessel, such as RV1 shown in the attached
FIG. 1. FIG. 1 is a schematic diagram of a biodiesel plant in
accordance with the Continuous Flow Application.
[0006] The methanol reacts with the fatty acid in the oil and
produces a methyl ester material. Then, the methyl ester material
(treated raw material) is sent to a settling tank ST1 where the
sulfuric acid, methanol and water can be removed by gravity
separation, settle to the bottom and may be drained, refined and
reused. The treated raw material is then reheated in a batch
process, or kept heated in a continuous process, and mixed in a
second reaction vessel RV2 with more methanol, and also with a
catalyst, such as potassium hydroxide (KOH) or sodium hydroxide
(NaOH). A reaction known as esterification takes place, creating a
mixture of raw or crude biodiesel fuel, and excess methanol, and
catalyst. This mixture is sent to a second settling tank ST2. In
that tank, the crude biodiesel fuel rises to the top, while the
methanol, glycerol and some fatty acid soap sink to the bottom of
the tank.
[0007] To minimize the amount of soap, excessive methanol is
typically used. That is, more methanol is used than is necessary to
react with the amount of raw material. It is desireable to recover
this methanol. Moreover, it is desirable to remove any entrained
methanol and any other unreacted substances from the crude
biodiesel. This is done conventionally by mixing the crude
biodiesel with water at mixer 51, then separating out the water
having methanol and glycerol from the biodiesel at separator 52
(e.g., a centrifuge or a separator tank).
[0008] In this water rinse and dry cycle, the water attracts excess
methanol and glycerol. Therefore, the biodiesel (oil) comes out
with "impurities" removed or minimized, and water with entrained
methanol and glycerol 42 also comes out of the rinse/dry process.
The rinse/dry process may be performed multiple times, typically
two to four times, on the biodiesel (oil), each time producing more
contaminated water.
[0009] Water with methanol is not easily disposable, since the
methanol therein makes the water contaminated, i.e., a hazardous
material, e.g., under EPA standards. The contaminated water can be
boiled and condensed (distilled) to remove the methanol. This
distillation process is expensive, because of the relatively high
amount of methanol and the large amount of water.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a schematic diagram of a biodiesel plant in
accordance with a continuous flow process, one type of process to
which the system of the present invention may be applied;
[0011] FIG. 2 is a view similar to FIG. 1 showing a modification of
the plant in accordance with a first embodiment of the
invention;
[0012] FIG. 3 is a view similar to FIG. 2 showing a modification of
the plant in accordance with a second embodiment of the
invention;
[0013] FIG. 4 is a partial schematic view of a condenser and
related equipment in the embodiment of FIG. 3;
[0014] FIG. 4A is a partial schematic view of a condenser and
related equipment similar to FIG. 4 with modifications;
[0015] FIG. 5 is a schematic view of a mixing tank and related
equipment in the embodiment of FIG. 3;
[0016] FIG. 6 is a schematic view of an overall biodiesel plant
structure in accordance with a third embodiment of the
invention;
[0017] FIG. 7 is a schematic view of a batch process plant having
crude biodiesel, methanol and other impurity separation structure
similar to that of the first embodiment of the invention; and
[0018] FIG. 8 is a schematic view of a batch process plant having
crude biodiesel, methanol and other impurity separation structure
similar to that of the second embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0019] With reference to FIG. 1, it has been proposed to use a
methanol removing substance in place of the water rinse (separator
52) to remove methanol from the biodiesel, e.g., a silicone based
gel adsorbent of a type explained below, previously used to reclaim
oils in the food industry. FIG. 2 shows such an arrangement. After
settling in ST2, crude biodiesel with entrained impurities
including methanol and glycerol (glycerin) leaves the crude
biodiesel portion 101 of the plant and enters the crude biodesel
with methanol separation portion 201 of the plant. Specifically,
the crude biodiesel with methanol and other impurities enters a
tank 60 where it mixes and reacts with silicone gel 61. The
biodiesel fuel, after about ten to fifteen minutes or more, is then
passed through a filter 62 and is finished biodiesel 64 ready for
use. It may then be cleaned, stored, shipped, or otherwise handled,
as is conventional.
[0020] The present inventor has experimented with such silicone
based gel, and found that this process removes methanol and
glycerol. However, in doing so, a relatively large amount of gel
must be used, making the process relatively expensive.
[0021] As explained above, after settlement in tank ST2, the crude
biodiesel still has some methanol entrained in it. It is better to
err on the side of too much methanol in the crude biodiesel portion
10', rather than too little, because if there is too little the
process makes a lot of soap. Generally, two to four percent
methanol is entrained in the biodiesel. The methanol is relatively
valuable, and can be reused in the transestestification process. To
meet ASTM standards, currently D6751, the biodiesel is
conventionally processed by vacuum distillation, which is very
expensive and in some cases may still not be sufficient to meet the
standards.
[0022] More specifically, the conventional process of removing
methanol from crude biodiesel is to perform wash and dry cycles as
explained above and further explained below.
[0023] The crude biodiesel is mixed with ten to thirty percent
water which has an affinity for the trapped methanol. The water
grabs the methanol and any glycerin (which is a small amount).
Then, the water with the methanol (and any glycerin) is separated
from the biodiesel, e.g., by centrifuge or gravity separation.
Alternatively, separation of the biodiesel is achieved by putting
the biodiesel and water in a settling tank to sit for several hours
or more. The water with methanol and glycerin dropout from the
biodiesel, which goes to the top.
[0024] Typically, two or four cycles of this process are performed.
To remove the methanol (and glycerin and sometimes other by
products) from the water, a large and complex condensing system
must be used. The water cannot be disposed of without a special
permit, because the water is contaminated.
[0025] The biodiesel also still has entrained water, so it must
still be heated and run through a vacuum evaporator to get rid of
the remaining water.
[0026] Use of water washing and a vacuum "flash" evaporator
("falling fill vacuum flash evaporator") is very expensive, yet it
is still industry standard.
[0027] In accordance with a preferred embodiment of the present
invention as shown in FIG. 3, the crude biodiesel (formed at the
separator ST2) is sent to crude biodiesel with methanol removal
apparatus 201a which starts with a heat exchanger 82 which boils
off the entrained methanol. With reference to FIGS. 3 and 4, crude
biodiesel is heated in the exchanger to at or about 240.degree. F.
or more, e.g., most preferably about 240.degree. F. to about
280.degree. F., well above the boiling point of 149.degree. F. (at
one atmosphere) of methanol alone.
[0028] At this high temperature, the methanol evaporates and is
sent to a condenser 85, and may then be reused (at 12a). In the
heat exchanger, the crude biodiesel is preferably heated by
numerous pipes 82a, and is re-circulated from an outlet 83a via a
pump 83. The biodiesel is sprayed on to any exposed heated pipes
82a by a spray nozzle 83b after traveling through recirculation
pipe 83c. The heated fluid in the pipes is preferably at about
250.degree. F. or higher, i.e., at least a temperature high enough
to boil methanol from crude biodiesel. This temperature is well
above the normal methanol boiling point of about 149.degree. F.
[0029] Remaining liquid is continuously re-circulated, preferably
by a high volume pump at about eight to about ten times the speed
that the crude biodiesel is entering the heat exchanger. The heat
exchanger is preferably an elongated tank, and preferably is set at
an angle, such as shown in FIG. 4. The angle is selected to
maintain most of the biodiesel near the bottom end so it is has
sufficient residence time to be heated by the pipes located at and
near the low end.
[0030] In addition, the outlet 83a is roughly about half way or so
up the tank. This helps ensure that the biodiesel will have
sufficient residence time in the tank, and be sprayed over and over
again onto the heated pipes. A partition 89 placed above the pump
has apertures to allow methanol vapor to pass, and to slowly allow
liquid biodiesel to pass, and also to help ensure sufficient
residence time in the tank.
[0031] It is important to note that while one could remove a lot or
perhaps all or virtually all of methanol using the heat exchanger,
a more preferred embodiment of the invention allows the biodiesel
to exit the tank at outlet 87a with a small amount of methanol
still in it, e.g., less than one percent or other small percent of
the entrained methanol.
[0032] The methanol vapor passes through an outlet 87b condensed by
being sent through a tube or pipe to a condenser. Any entrained
glycerin, liberated by the heating, falls to the bottom and may be
drained, e.g., periodically.
[0033] The demethalated biodiesel 84 is sent to a tank 88 (FIGS. 3
and 5) for mixing with a methanol-removing substance, preferably, a
magnesium silicate adsorbent, e.g., 2 MgO.65:02 nH.sub.2O (CAS
Number 1343-88-0), referred to above as gel (although it can be in
powder form). Suitable compounds, often synthetics, are available
commercially, such as Magnesol.RTM. (e.g., R60) sold by The Dallas
Group in Indianapolis, Ind.
[0034] The adsorbent is mixed with the biodiesel. After a period of
time, e.g., about ten to fifteen minutes, is passed through a
filter 90 (FIG. 3) such as a plate filter 90a, e.g. a star filter
press, and a fine filter 90b (e.g., about two microns) producing
finished biodiesel fuel. While the gel (adsorbent) could be used on
crude biodiesel without the heating and condensing of the crude
biodiesel to boil off some methanol, the gel might have to be used
in a relatively large amount of anywhere from about one to four
weight percent of the crude biodiesel. By contrast, by first
boiling off some methanol, the gel need only be used in an amount
of less than one weight percent, e.g., at or about 0.4 to at or
about 0.8 weight percent, or even less, where the biodiesel is at a
temperature of at or about 150.degree. F. to 200.degree. F.
[0035] Another overall view of the biodiesel plant process is shown
in FIG. 6, which is preferably for use of soy bean oil as raw
material. If yellow grease is used, an additional stage of
treatment with H.sub.2S and methanol may be provided before
entering the reactor where the soybean oil is shown entering.
[0036] Heat exchanger 82 may be a conventional heat exchanger
raised at one end and modified as shown in the drawings and
described herein, including the angle, which need only be
relatively small. For example, stand 91 as shown in FIG. 4 need
only raise one end about three feet for a thirty four foot long
tank 87. A larger or smaller height will also work, but preferably
the height that one end is raised is about the same as the diameter
of the tank.
[0037] With this angle, the heat exchanger with separator 89 is
filled about one half way with liquid biodiesel and is used herein
as a methanol (vapor) extractor. The low end of the tank 87 allows
glycerin to collect there (due to its high specific weight relative
to the biodiesel). The glycerin thus can be periodically removed as
needed.
[0038] The high volume pump circulating and re-circulating the
biodiesel fluid serves to mix the fluid and help ensure residence
time and thereby sufficient heating. In addition, the spray onto
exposed pipes of the heated pipes greatly increases the heating
effect and thereby increases the speed of methanol removal.
[0039] The partition upstream from the recirculation outlet and
pump enable a partial separation of new biodiesel fluid entering
the heat exchanger from the demethalated biodiesel exiting the tank
at outlet 87a, deterring mixing and increasing residence time.
[0040] The angling of the vapor tube down to the cooling tower
(condenser) enables condensing to start in the tube, as liquid will
flow down the tube to the cooling tower. Accordingly, extending the
vertical portion of the vapor recovery tube from the vapor outlet
87b of the tank, e.g., about eight or nine feet, provides height
for the inclined portion to go down into the cooling tower. To
prevent or minimize condensing in the vertical portion, insulation
95 may be used on tube 97.
[0041] FIG. 4a shows a similar structure as FIG. 4 where like
reference numerals have been given like numbers, as throughout the
drawings. One important variation is that a heat exchanger 205 is
added to preheat the crude biodiesel with impurities. This
preheating is preferably above 140.degree. F. and may be as much as
220.degree. F. or more. At 220.degree. F., the methanol and
glycerin are separated out very quickly, e.g., about seven minutes.
The other changes to the structure of FIG. 4 as shown in FIG. 4A
mainly concern the positioning of the elements having a
corresponding number to FIG. 4 but with one hundred added to
it.
[0042] In tank 187, heat exchanger pipes 182a are provided at both
the low and high ends of the tank. Recirculation pipe 183c sprays
biofuel on the pipes at the high end at nozzle 183b. Demethalated
biodiesel is taken at the outlet 187a.
[0043] The present inventor has also found that the esterification
reaction creating the crude biodiesel which rises to the top of the
reactor RV2, and the glycerin by product which falls to the bottom
of RV2 may be sped up by heating RV2 well above the conventional
110.degree. F. In the past, in the batch process, this reaction
took several hours at 110.degree. F.
[0044] In the process of the continuous flow Application, whether
by batch or continuous flow, the reaction in RV2 takes about one to
two hours at 140.degree. F. to 145.degree. F. It has also been
found that this process can be accelerated even more, to only about
eighteen minutes, if heated well above 140.degree. F., e.g., from
at or about 156.degree. F. to at or about 158.degree. F. Because
methanol boils at 149.degree. F., raising the temperature to
140.degree. F. and certainly to 156.degree. F. or more can cause
substantial methanol loss. That is extremely undesirable because
methanol is a health hazard, and also potentially explosive. If a
sealed top is placed on the tank, the pressure build up may be
considerable. Therefore, in accordance with another aspect of the
invention, the inventor places a condensing coil at the top of the
tank, which is connected to a vacuum pump and scrubber. The vacuum
pump maintains a slight negative pressure at the top of the tank.
Therefore, no methanol fumes can escape. A small amount of fresh
air is allowed to enter into the top of the tank which is under
negative pressure. Any methanol vapor will be sucked into the
condensing coil at the top of the tank along with some fresh air.
As the methanol vapors rises, it condenses in the coils and becomes
a liquid and returns as a liquid into the top of the reactor, and
gets remixed with the incoming soy oil and methanol catalyst. Only
very small amounts of methanol vapor will reach the scrubber.
[0045] The present inventor has also discovered that the gel
attracts methanol first from impurities in the crude biodiesel.
After all the methanol has been bonded to the gel, then the free
gel attracts glycerin. After all the glycerin has been bonded to
the gel, then the free gel attracts potassium (or sodium)
hydroxide. By contrast, the biodiesel industry would likely teach
that adding water at this stage would be undesirable, because it
would form an emulsion.
[0046] Therefore, as shown in FIG. 2, a modification of this
embodiment of the invention is to add water 61a to the gel and
crude biodiesel mixture in the mixing tank 60. Preferably, the
amount of water added is about one percent weight of the contents
of tank 60. The result of adding water is that methanol, glycerin
and potassium (or sodium) hydroxide are attracted to the water at
the same time, and the gel then attracts the water with the
methanol, glycerin and potassium (or sodium) hydroxide. For
example, the water and gel are added to the tank 60, and then the
contents are mixed, e.g., for ten minutes.
[0047] When the water is used, the amount of gel used may be
reduced from the amount needed without water, to reach the same
level of impurity removal. Therefore, the amount of gel may be
reduced below 0.4 to 0.8 weight percent, i.e., below 0.4 weight
percent.
[0048] It is noted that the gel will also attract some biodiesel.
This biodiesel could be reclaimed, but normally the amount is
negligible.
[0049] FIG. 7 shows a biodiesel plant which is a batch process
plant. Yellow grease 2', sulfuric acid 4', and methanol 6' are
added to a first reaction vessel RV1'. The resultant liquid is
drained at draining mechanism 103 after several hours. They are
drained first and may be reused at unit 12'. The remaining mixture
may be drained at mechanism 104 and added to reaction vessel RV2'
along with potassium (or sodium) hydroxide and methanol. After
several hours the contents are drained by draining mechanism 106
and added to second settlement tank ST2'. After several hours
glycerol 40' is drained out, followed by removing the crude
biodiesel with methanol and other impurities at mechanism 108. The
remainder of the structure is the same as section 201 of FIG.
2.
[0050] In FIG. 8, batch plant 101 is followed by sending the crude
biodiesel to section 201a, which is the same as unit 201a of FIG.
3.
[0051] Due to the fast reaction, glycerin accumulates quickly at
the bottom of the reactor tank and/or separator tank. Accordingly,
the height of these tanks may be increased to help pressure push
the glycerin out of the bottom of RV2 and/or ST2.
[0052] Although the invention has been described using specific
terms, devices, and/or methods, such description is for
illustrative purposes of the preferred embodiment(s) only. Changes
may be made to the preferred embodiment(s) by those of ordinary
skill in the art without departing from the scope of the present
invention, which is set forth in the following claims. In addition,
it should be understood that aspects of the preferred embodiment(s)
generally may be interchanged in whole or in part.
* * * * *