There have been far too many accidents and fires related to biodiesel production.
Because the process of making biodiesel is relatively simple does not mean that it does
not involve hazardous chemicals.
Fires and explosions are the main type of serious accidents that have occurred producing
biodiesel and methanol is consistently the main reason.
This video attempts to improve the awareness of methanol in biodiesel production so that
future accidents can be avoided.
Methanol, technically known as methyl alcohol, is a colorless alcohol with the chemical formula
CH3OH.
It is the simplest alcohol with its molecule only having a single carbon.
Methanol is a volatile solvent widely used as a feedstock
to produce chemicals to make adhesives, plywood, windshield washer fluid, and many other products.
About 40% of the methanol on the market is used as a fuel or fuel additive
It is also used for producing biodiesel via the transesterification reaction.
Methanol is highly toxic when ingested,
inhaled or even absorbed in the skin.
Ingestion of even one or two ounces of methanol may cause death and lesser amounts are known
to have caused irreversible blindness.
Since methanol absorbs through the skin and other tissues directly into the blood stream,
users must not breathe methanol vapors or allow vapors or liquid to contact skin.
Personnel working with methanol must wear protective
clothing, chemically resistant gloves, a breathing mask that captures organic vapors and a full
face shield.
The cartridge in the breathing mask should also be changed regularly.
Although understanding the toxicity of methanol is clearly important, the single largest safety
hazard of methanol with biodiesel production has proven to be it is an easily ignited liquid
and sometimes explodes in air.
Methanol burns with a low-temperature flame that may be invisible and is slightly heavier than
air so that it may migrate near the ground and collect in confined spaces and low-lying areas.
In certain specific circumstances, methanol vapor may explode rather than burn on ignition.
Here is a demonstration that shows part of the reason methanol can be so dangerous.
Hello, I'm Keegan Duff with the University of Idaho
The following are a series of simulated indutrial accidents.
This 300 gallon reactor tank we use to make biodiesel.
For our purposes today the tank is empty, and there's no fuel load except what we put on externally.
This fire is with anhydrous methanol.
This fire is not visible to the human eye.
An operator could easily walk up to the fire and be engulfed and not even realize that there was a fire.
I can feel the heat waves coming off of the reactor, but I can't actually see any of the flame.
It's essential for any biodiesel plant using ethanol or methanol
To have a monitoring program to detect the presence of vapors
It's also essential any firefighting team that's going to put out a fire with methanol or ethanol to have access to infrared cameras.
A good start to properly handling methanol is to carefully read the Methanol Institute’s,
“Methanol Safe Handling Manual” which is available on their website (methanol.org).
It is also important and typically required to have a material safety data sheet, or MSDS,
for methyl alcohol available in a prominent location where methanol is being stored and
used.
Federal regulations require a process safety management, or PSM program, if more than 10,000
pounds (or 1,517 gallons) of methanol is present in a production facility. All but the
smallest of plants have more than this.
But even small plants should implement a program for employees.
Methanol must be stored in a well-ventilated dedicated location, where it is protected
from heat and ignition sources.
Methanol is an electrically conductive, polar compound so all storage materials, including
totes and drums, should be grounded to avoid hazards associated with static discharge and
all electrical systems must be fully enclosed and explosion proof.
Plastic containers cannot be grounded and should not be used for methanol.
In recent years, attention has been drawn to the hazard of using personal electronic
items, such as cell phones and laptop computers, in potentially explosive atmospheres.
The energy necessary to ignite methanol vapors may be similar to the energy produced by static
electricity and by sparks generated by low-voltage electrical devices when they are turned on.
As a rule, electronic devices such as cell phones and laptops should not be used within 20 feet of a potentially
explosive atmosphere.
Normally methanol vapor, being only slightly heavier than air, will dissipate from ventilated
locations, but do not expect it to dissipate from non-ventilated locations and enclosed
spaces.
The concentration of methanol in air necessary for combustion is approximately four times
greater than that for gasoline.
However, methanol releases less vapor than gasoline and the temperature of methanol
must be elevated in order to generate vapor concentrations necessary to support combustion
in air.
In order to prevent the methanol from absorbing moisture, it must be stored in a sealed container.
The sealed container should have an allowance for thermal expansion; otherwise, changes
in temperature may cause the methanol to expand and rupture the container.
Methanol containers are also subject to Boiling Liquid Expanding Vapor Explosion (BLEVE) when
heated externally.
Methanol storage requires appropriate secondary containment.
The National Fire Protection Association standards require secondary containment of at least
110% of the volume of the largest methanol storage tank but best practice dictates considerably
more.
Methanol is totally miscible in water and can be diluted with four parts water to one-part
methanol and still be considered to be a flammable liquid.
This has important consequences for firefighting.
Insufficient freeboard within the secondary containment area can result in overflow and
a so-called “running fire.”
Running fires are difficult to control.
Methanol storage tanks should be labeled with a label that includes a hazard symbol.
All piping and valves subject to carrying methanol should be consistently labeled, and
direction of flow should be indicated.
Each piece of plant equipment needs to be evaluated for safety.
Operator and employee safety training is essential.
Understanding the basics of the entire process, access to Material Data Safety Sheet information,
and knowledge of each material used is necessary for every employee.
A variety of precautions must be observed during the production of biodiesel.
For instance, it is desirable to preheat the waste oil prior to the transesterification reaction.
This must be done carefully to prevent oil spattering and accidental ignition when the
catalyst is added.
A closed reactor, whether batch or continuous, is preferable to a reactor that is open to
the atmosphere.
Temperature control throughout the process is critical to safe and efficient operation.
If the temperature rises too high, and agitation is too vigorous, then fire and/or explosion
are possible.
If the temperature is too low and agitation too gentle, then the reaction will not go
to completion.
The main reactor and other processing equipment will be laden with methanol vapors at various
times during biodiesel production and the best practice is to transfer all methanol-laden
fluids via tubing into closed vessels, and to vent all vessels to the outdoors.
Methanol fumes will also be present when glycerol is drained from the reactor, and when raw
biodiesel is pumped from the reactor to wash tanks, especially if these fluids are drained
while hot.
Both glycerol and waste water will contain significant methanol
Never grind or weld a container that contains or used to contain methanol or glycerol.
Methanol recovery has some inherent safety concerns,
and should only be carried out by advanced producers who fully understand the safety
issues involved with handling methanol and hot liquids.
Methanol fires are best extinguished by oxygen starvation with dry chemical powder, carbon
dioxide, and alcohol-resistant foam.
It is good practice to have two fire extinguishers at opposite ends of the workspace.
When using a portable extinguisher, it is necessary to aim at the base of the flames,
not at the flames themselves.
If ignited, methanol vapor can flash back to its source.
Water is a second choice to extinguish a methanol fire.
Water in the form of a fine mist will absorb vapors, quench heat, and provide a curtain
shield for upwind advancement.
However, with large methanol pool fires the volume of water must be 4 to 5 times the volume
of the methanol pool and secondary containment should be capable of holding a volume 4-5
times larger than that of the methanol pool.
Biodiesel production plant is a chemical plant and must be treated accordingly.
There is nothing more important than the safe handling of methanol in order to protect your
health and that of your co-workers, your workplace, the environment, and your community.