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Pilot unit for drill cuttings treatment
Induction Thermal Desorption Unit
(ITDU)
Technical specification
2015
Table of contents
1. Introduction .............................................................................................................................. 2 2. Objective and scope ................................................................................................................. 3 2.1. Final product of pilot unit ITDU .......................................................................................... 4 3. Cuttings treatment process ....................................................................................................... 5
3.1. Pretreatment screening .......................................................................................................... 5 3.2. Treatment process technology .............................................................................................. 5 3.3. Feed hopper to supply material to the unit ........................................................................... 6 3.4. Process chamber ................................................................................................................... 7 3.5. Discharge system .................................................................................................................. 7
3.6. Gas line ................................................................................................................................. 8 3.7. Scrubber ................................................................................................................................ 8 3.8. Condenser - Separator ........................................................................................................... 8
3.9. Control panel ........................................................................................................................ 9 4. Pilot unit design history ......................................................................................................... 10
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1. Introduction
One of the main environmental concerns is pollution caused by oil and gas industry. Drilling
process wastes pose the highest risk to natural environment. These wastes contain lots of various
chemical agents with different level of environmental hazard. Lots of cuttings pits appear during oil
and gas well drilling.
Photo 1. Drilling rig with cuttings pit Photo 2. Oil drill cuttings sample
Content of oil products in drill cuttings is in the range from 2000 to 13870 mg/kg where 5,6% - gums,
20,1 % - polycyclic aromatic hydrocarbons.
When drill cuttings are heated at temperature 300 С°, toxicity level of drill cuttings is decreased by 10
times and at 500 С° drill cuttings are totally detoxified.
Photo 3. Graduated cylinder shows content of mineral oil and water obtained in the lab by using retort
from drill cuttings. Sample of drill cuttings was taken for analysis from cuttings pit.
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2. Objective and scope
Pilot unit ITDU was designed for experimental and test work. Main purpose of ITDU is to treat
different oily wastes such as:
soil contaminated by emergency spill of oil and oil products;
solid phase obtained after pretreatment of liquid oil wastes (oil sludge) such as after “three
phase” centrifuging;
solid bottom sediments from oil storage tanks and heavy oil products (residual fuel oil)
waste catalysts used during oil treatment and etc.;
typical cuttings, drill cuttings or waste drilling mud;
Photo 4. Cuttings pit in Africa Photo 5. Cuttings pit in Russia (Siberia)
Photo 6. Cuttings pit
Proposed desorption system can provide treatment of drill cuttings containing:
Hydrocarbons 15%
Water 15%
Content of hydrocarbons in treated material is less than 1% normally from 0.5 to 0.1%.
Average capacity of pilot ITDU based on feed material is up to 100 kg/hour. Content of such feed
material can be different.
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2.1. Final product of pilot unit ITDU
Final product of the unit includes the following:
Treated drill cuttings (dry solid phase in the form of fine grained sand and fine dust)
Treated non-condensable gas to be filtrated by using chemical solution and carbon
filter before discharging to the atmosphere
Treated hydrocarbon phase (oil, fluid paraffin, diesel, synthetic and mineral oil)
Process water. Water has peculiar odor and requires additional treatment.
Photo 7. Samples taken during treatment of oily cuttings (technical water, oil and dry
solid phase)
Photo 8. Clay, water and diesel Photo 9. Dry clay after ITDU treatment
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3. Cuttings treatment process
Cuttings treatment process using ITDU involves transferring of heat to the material resulting in rise of
temperature higher than evaporation point of volatile compounds contained in the treated material.
Process of hydrocarbons extraction from drill cuttings involves heating of the material through
process chamber wall. High temperature in process chamber allows to heat drill cuttings up to boiling
temperature of liquid phase which is then transferred into gas phase.
Next process step is gas condensation. Gas vapor is transferred from gas phase into liquid phase due
to cooling in the condenser. Last process step is separation where liquid phase is separated into two
fractions water and oil.
3.1. Pretreatment screening
ITDU can treat not only drill cuttings but also different oily wastes such as: contaminated soil, bottom
sediments from oil storage tanks, old cuttings from pits. Prior to loading the material to feed system, all
large foreign objects (metal, stones and etc.) shall be removed from feed material.
Photo 10. Abandoned cuttings pit with debris Photo 11. Abandoned cuttings pit with debris
Generally incinerators or pyrolysis cycle plants are used for disposal or removal of contaminated
debris.
Induction Thermal Desorption Unit consists of the following process modules:
1. Feed hopper
2. Feed conveyor
3. Process chamber
4. Induction unit
5. Discharge system
6. Scrubber
7. Condenser
8. Oil/water separator
9. Cooling system
10. Control panel
11. Non-condensable gas treatment system
3.2. Treatment process technology
Drill cuttings are loaded to ITDU feed hopper by additional equipment and then feeding directly to
ITDU process chamber by double-screw conveyor. Indirect heating of feed material takes place into
process chamber. Process chamber is heated by induction to operating temperature, which may vary
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from 300 С° to 550 С° depending on chemical contaminants of feed material. High temperature allows
drying of drill cuttings ensuring maximum removal of hydrocarbons. Specially designed shape of
inductors allows to maximum heat process area where material is passing.
ITDU process technology is characterized as continuous process – 24 hours/day. ITDU is referred to
“explosion hazardous” category.
Photo 12. Installation of pilot unit ITDU
3.3. Feed hopper to supply material to the unit
Feed hopper with capacity 0,2 - 0,3 m3 is cone
shaped. Feed conveyor is double-screw conveyor
allowing to feed material with different viscosity.
Feed rate is monitored by control system – frequency
converter which allows controlling material volume
in process chamber to maintain desired operating
temperature. There is always some level of material
in the hopper. Inlet material prevents air to come into
process chamber and does not let gas to come out
from chamber as well.
Photo 13. Clay and water for initial tests
Level transmitter is installed on top of the
hopper. This transmitter shuts down feeding
conveyor if material level in the hopper is
decreased (Critical level or minimum level
required to keep chamber sealing).
Photo 14. ITDU feed hopper
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3.4. Process chamber
Drying of feed material takes place in process
chamber.
Process chamber is equipped with induction heating
system. Induction allows heating of process chamber
to operating temperature (300 - 500 С°) quickly and
within the accuracy of about 1 С°. Process chamber is
equipped with special mixing screw which prevents
material from sticking when moving in process
chamber. Mixing screw ensures effective mixing of
the material resulting in hydrocarbons removal and
improvement of heat exchange. Speed of mixing
screw is varied from 10 to 50 rotations per minute
depending on initial characteristic of treated material.
Photo 15. Process chamber without screw
Material is heated due to heat transfer through process chamber walls. Process chamber is heated by
inductors installed directly on process chamber. At temperature 300 С° water and hydrocarbons
components are transferred into gas phase. Water and hydrocarbon vapors are leaving process chamber
to scrubber via gas line and then to condenser-separator. Operating pressure in process chamber is in
the range from 20 to 60 mbar. Treated material in the form of solid phase is discharged from process
chamber via outlet box. Solid phase fraction is similar to fine grained sand. Outlet box has screw
conveyor, on-off position of which is controlled by level switch. It ensures continuous availability of
dry material in outlet box preventing entry of atmospheric air and discharge of gases from process
chamber.
3.5. Discharge system
Treated material is discharged by screw
conveyor from outlet box-1 to outlet box-2.
System of discharging solid phase from
process chamber includes angled screw
conveyor connected with outlet box. Outlet
box-1 and Outlet box-2 are used as seal to
block air entry to process chamber. Both
boxes are equipped with level switches
controlling sufficient quantity of dry material
to keep low pressure in process chamber and
avoid vapor leak.
Photo 19. Dried cuttings discharge system
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3.6. Gas line
Water and hydrocarbon vapors carry out ultra-fine particles to gas cleaning pipe, most of particles hit
flights of cleaning screw and settle down to the bottom. Gas pipe is equipped with special type of
screw to be able to clean gas pipe from layer of
collected particles.
Cleaning screw of gas system is generally off and
is started by timer for a short period to clean gas
pipe.
Photo 16. Gas line with installed screw
3.7. Scrubber
After passing through gas line, water and hydrocarbon
vapors are moved to oil scrubber for removal of remaining
solid particles. The main purpose of scrubber is to clean
vapors from remaining solid particles by spraying hot oil.
Scrubber is continuously filled with condensed oil (oil,
diesel or liquid fuel). Level switch controls oil level in
scrubber, surplus oil is pumped into filtration tank.
Photo 17. Scrubber
3.8. Condenser - Separator
Condenser is closed tank with several spray nozzles where vapor condensation takes place due to
water spraying. Spray nozzles can operate both in automatic and manual modes.
Water from separator is circulated in the system via heat exchanger in continuous mode maintaining
operating temperature of condenser.
Separator is installed under condenser and is used for separation of water and hydrocarbon phase.
There is divide wall in the middle of condenser which allows condensed liquid to flow from condenser
to separator section. Divide wall enters separator section at an angle forming hydraulic seal. Separator
is used to separate condensed liquid into water and oil phases (oil, diesel or liquid fuel).
Process water is pumped from one side of separator and recovered oil is pumped from another side to
storage tanks. Small quantity of gas which isn’t condensed in vapor condenser will be discharged from
the unit via carbon filter.
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Recovered oil can be used for preparation of
oil drilling mud, as heating oil and also as
fuel for diesel generators depending on
quality of recovered oil.
Process water produced during desorption
has peculiar strong odor and is unsuitable
for reuse. Process water requires additional
treatment for further use on a drilling rig or
disposal. Process water was treated by using
carbon filter in laboratory conditions.
Another treatment test was done by using
ozone and process water was cleaned 60 -
70%.
Practically process water is mixed with
treated water and then it is treated in
bioreactor by bacteria.
Photo 18. Condenser – separator
Mixture of diesel fuel, used motor oil, water and dry clay was used as feed material during ITDU
testing.
3.9. Control panel
Control panel of the unit is divided into two parts. Computer is installed on top of the panel for
operation and adjustment of induction equipment. Automatic starters for electrical equipment are
located at the bottom of control panel. The unit can operate both in automatic and manual modes. The
unit is equipped with audible alarm. In case of emergency shutdown or power supply interruption, the
unit is in safe operation mode. ITDU is equipped with emergency shutdown buttons.
Photo 19. Assembled pilot unit
During testing of the unit control panel was forcibly switched off for safety check.
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4. Pilot unit design history
In 2014 four specialists of different disciplines from different countries joined into one team to design
and manufacture pilot Induction Thermal Desorption Unit. 1. Vladimir Gargoma – Russia, Belgorod, International specialist, 15 years of work
experience with different type of TDU.
2. Evgeny Krokhmal – Russia, Tomsk, Director LLC “Ambit”, 14 years of work experience,
design and operation of induction equipment
3. Dmitry Kolganov – Ukraine, Odessa – Individual entrepreneur, 7 years of work
experience, UTD design and operation (pyrolysis plants for tires and plastic disposal)
4. Tore Ausland – Norway, Moss – CEO “Quality Group AS”
In 2015 pilot unit was tested in Tomsk in workshop of “Ambit” company. First successful results
were obtained in March, 2015. In June, 2015 Norwegian company “Quality Group AS” made decision
to manufacture ITDU-1.5 with capacity 1.5 - 2 tons/hour.
Photo 20. Vladimir, Tore, Evgeny and Dmitry
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