Fuels & Lubricants Magazine

GREEN CORNER
biomass into bio pyro oil, and gas and char as side-products.
Capacity is 24 kt/y by BTG’s rotating cone technology.
14 The stream is used for electric power generation
in nearby industry. Bio pyro oil is co-feeds boiler system
for heating of Friesland Campina Company with natural
gas.
Ensyn, Canada has operated over 25 years, and with
Rapid Thermal Technology processes over 21 kt/y from
wood residues. 17 Production focus is on fuels for heating
and cooling purposes, and on refinery feedstock to
produce renewable ‘drop-in’ gasoline and diesel, and as
a chemical feedstock to produce food flavourings and
fragrances. To date, Ensyn has designed and built seven
commercial RTP plants in the United States and Canada
for use in the manufacture of more than 30 commercial
products ranging from food flavourings to adhesive resins
for construction. 18
Valmet developed technology for bio pyro oil production
in riser reactor and delivered hundreds of fluidized
bed boilers worldwide, with the intention to expand biooil
production with integrated pyrolysis technology. 15
Co-processing provides
production of products
related to standard
specifications for
transportation fuels and
therefore does not require
segregated handling and
distribution downstream of
the refinery.
Challenges in Co-processing
The principle of co-processing is adding of bio-crude in
some part of refinery streams with minimal unit modifications
and process conditions changes. Co-processing
provides production of products related to standard
specifications for transportation fuels and therefore does
not require segregated handling and distribution downstream
of the refinery, as is the case with some other
renewables, as ethanol and biodiesel. 19
A lot of challenges of co-processing in different units
is present in combination with refinery streams and in
laboratory analytics. Some of them are further: possible
incompatibility with refinery feedstock, the effect
of water forming on process parameters, catalyst and
products, changes in kinetics and conversion, including
influence on material balance and product distribution,
yield and quality.
Bio pyrolysis oil is not possible to use directly as blending
component in transport fuels without upgrading
process. 20 The first choice of bio pyro oil co-processing
is FCC unit. The bio pyro oil changes a part of standard
FCC feedstock, vacuum gas oil (VGO). From literature
is unknown the exact amount of added bio pyro oil for
co-feeding, but more than 5 % is not recommended in
this phase, due to nature of bio pyro oil and insufficient
readiness of technology. 14 The pyrolysis oil complexity
and very different properties from petroleum feedstock
and products are the main problems in co-processing.
In FCC co-processing the main challenges are connected
with unknown bio pyro influence on process
parameters, catalyst activity and product distribution
and quality. The usual FCC reactions take place during
biomass conversion. Detail mechanism is described in
2, 11
literature.
Some companies have conducted trials and demonstration
of FCC co-processing in different scale including
commercial unit. Petrobras published articles about
carried out of testing in FCC demonstration-scale unit.
The different yield distribution is obtained by adding a
different amount of bio pyro oil. A general conclusion is
that coke and gas yield increased, while gasoline and light
cycle oil varies depends on the added amount of bio pyro
oil. The most oxygen was removed as water, CO and
CO 2
during cracking process. Some amount remained in
liquid products as alkyl phenols in co-processed gasoline
and diesel products. The produced light cyclic oil was
tested and found suitable for hydrogenation as diesel
blendstock, while gasoline hydrogenation tests were also
1, 11, 21
being conducted.
Due to the high acidity, it is necessary to take care of
bio pyro oil storage and feed line material. Stainless steel
is recommended. Furthermore, bio pyro oil is not miscible
with FCC feed and request separate entrance into
the reactor. The plugging of feed nozzle or feed line was
noticed in some literature. 22
Catalyst activity can drop if bio feed contents higher
amount of alkali and earth alkali metals.
Testing results of some laboratory small scale FCC
units suggest that feed behaviour in small scale is different
from larger or commercial scale units, especially in
coke formation. There are more complicated to predict
the behaviour of bio pyro in FCC commercial units and
their influence on full system and products. 1
It is very important to know how the renewable carbon
from co-processed biomass re-distributes in the range of
Fuels&Lubricants No. 2 JUNE 2018 33