What is Dry Washing?
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Dry Washing is a method used to remove the impurities from
biodiesel such as free glycerin, soap, catalyst and other trace impurities
without the use of water. There are
several different products available for the Dry Wash method and are available
at our various websites listed below.
However, this FAQ will include information on Ion Exchange Resins like
the Purolite PD 206 and the Thermax T-45 MP BD.
Purolite PD 206
Thermax T-45 MP BD
What is an Ion Exchange
Resin?
The resin beads work with a combination of Ion Exchange
(+Positive and –Negative Ions) “sites” located on the beads and
absorption. In layman’s terms they will
attract Ions like Na or K (from your catalyst) and absorb or coat them-selves
in glycerin. These leave the Biodiesel
free from impurities as it leaves the Vessel.
How do I use Purolite
or Thermax to purify my Biodiesel?
It is common practice to load the Ion Resin into a vessel to
create what is called a “Resin Bed”. This
simply means that the ion resins have been poured into a vessel and are resting
at the bottom. Most vessels are made
from Steel Pipe or rolled steel to form a cylinder. Some people may want to use PVC pipe, however
the PVC will crack after extended use.
Purolite Suggest a minimum of 24” bed depth – (How tall the
Resin Bed is)
Thermax recommends a 36” minimum.
Both Manufacturers suggests a 3-1 ratio of Resin Bed depth
(BD) to Diameter.
(EX: 24” BD = 8” diameter, or 36in BD=12” diameter).
The Manufacturers also suggest that you should allow for at
least a 50% expansion of the resin during the course of its life.
(EX: 24”BD=36”H or 36”BD=54”H)
FYI -- Purolite is 52lbs per cubic foot and Thermax is 38lbs
per cubic ft
What is the Recommended Flow Rate?
This can be factored by some simple math.
The following is a constant
2000lbs for a 15GPM
(gallon per minute) Flow Rate.
Therefore:
2000lbs = 15GPM
EX: You purchase 20lbs of Purolite
20lbs/2000 = 0.010
0.010 * 15 = 0.150 GPM or
9GPH
X= Amount of Resin you have
Y= Flow Rate of X
Y=(X/2000)*15
There will also need to be a support screen at the bottom of
the vessel to hold the beads in. Customers
can purchase the Ion Exchange Towers at www.biodieselexpertsintl.com/store
A diaphragm pump that is able to control the flow rate of
your desired column is recommended. (These can be pricy, so look for a good
used one as well). It is also possible to
use a centrifugal pump and use a globe valve to regulate flow to the tower and
recirculate that flow that does not go into the tower back to the original
tank. Also, some customers will purchase an inexpensive centrifugal pump and
use a ball valve to choke back on it to reach the desired flow rate.
How long does the
Resin Last?
This number is directly related to the quality of fuel that
is being produced. The life of the resin
typically is between 100 to 200 gallons per pound of Ion Resin. Therefore, we will use the 150 gallons per
pound as an average. For example, 20lbs,
this should last 3,000 gallons.
(20lbs*150 gallons = 3,000 gallons)
How do I know when
the resin is exhausted (used up)?
There are simple soap titrations to determine if the levels
have reached an unacceptable point. If available,
free glycerin tests can determine if the Resin Bed needs to be “washed”. They also expand upward as they are used and
some vessels will have a site glass.
What do you mean
Washed?
The Resin Beds are able to be cleaned out with methanol. This is a simple process of filling the
vessel with methanol to above the Resin Bed over night and then perform this
again about 3-4 more times (you don’t have to let it sit overnight this time,
only 20 min or so) until you see a clearer methanol. This methanol can be reused in the Base
transesterification but we would recommend using about 60% more of the used
methanol than you normally do.
The Beads will need to be dried of the excess methanol. Recommendations
are:
- Flush
Resin Bed with Demthylated Biodiesel, however you will then need to water
wash this biodiesel or remove the methanol in your own way.
- Take the
Ion Resin and spread them out in a safe area to air dry – DANGER -PLEASE
DO THIS IN A SAFE AREA
THERE WILL BE METHANOL VAPORS
- Purge
the tower with Nitrogen Gas until dry.
(Some people do this with Air, BEI does not recommend this, however
perform at your own risk)
Speaking of Methanol,
should I remove it before the resin?
The short answer is Yes.
However, it is not a necessity, it will still work, however it may not “last
as long”. A reduction of 20-25% is
commonly seen when used in this manner.
Some recommendations to remove the methanol before are:
Speaking of Methanol,
should I remove it before the resin?
The short answer is Yes. However, it is not a necessity, it will still work, however it may not “last
as long”. A reduction of 20-25% is
commonly seen when used in this manner.
Some recommendations to remove the methanol before are:
- 5%
Water wash before the Resin- let it settle out, drain and continue to
beads.
- Evaporate
the methanol out. This is commonly
called methanol recovery by flash evaporation. NOTE- THIS IS VERY
DANGEROUS SO PLEASE MAKE SURE YOU CONSULT A PROFESSIONAL. Heat and agitate the biodiesel to above
170F in a pressure vessel, pull the methanol vapors into a condenser to
covert them back to liquid form. Continue until biodiesel is free of methanol.
- Let
settle for an extended period of time in ambient or above temperatures.
- There is also a method called GL 1 Day
Process.
NEED TO KNOW MORE?
CONTACT US AND WE WILL BE GLAD TO ASSIST!
Ron
Urwin
Biodiesel Chemicals – Sales
Manager
281.317.8101
Nathan DeMartino
Biodiesel Experts
International – Sales Manager
281.992.1168