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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