Report (28) _Eu-P26 IS- OD 105
Attachment A ', 13 n, 2015
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Agilyx Tigard Feed Pre-Melt Process Descriptio Of fl(AR
BUILDING DIVISION
Agilyx is proposing to modify the mixed waste plastic(MWP) feed into the existing pyrolysis plastic
recycling unit (PRU) in two stages.The first stage (Stage 1) will be used to add a feed pre-melt process
and trial the new process.This testing period will last a maximum of 6 weeks in duration.After the new
pre-melt process is refined and proven,the new pre-melt process will be connected permanently to the
PRU in the second stage of the project.This Notice of Intent to Construct application is for the
equipment operating during the trial period in Stage 1 only.Another air permit application will be
submitted for the second stage of this project.
Overall Description for Stage 1 Pre-melt Process
Bulk MWP will be conveyed from the existing trommel feed bin,via a weigh belt to a compactor. The
MWP is compressed and fed into a double-arm mixer extruder(DAME) vessel that will mix and melt the
MSW. The DAME consists of a heat-jacketed chamber with 2 sigma-style mixers to agitate the bulk
material and an extruder screw to discharge melted material. The DAME will use a recirculating hot oil
system to provide heat transfer. The hot oil will be heated using electricity.
The DAME pre-melt vessel, which is being purchased as a used/reconditioned unit, will have a custom
top enclosure that will be vented to the existing Tigard quench tower. During Stage 1 trials,the existing
quench system, VSS and thermal oxidizer emission control device (ECD) will run to remove off-gases
created from the pre-melt process.The PRU will not be operated at the same time as the pre-melt
process.
During Stage 1, the DAME will discharge partially melted plastic into a mobile collection bin. The
collection bin also will be vented to the quench system and VSS to remove off-gas and sent through the
ECD for thermal oxidation. When the mobile collection bin is full, an empty mobile collection bin will be
rotated into its place.The full mobile collection bin will continue to cool before the plastic is removed.
During cooling, that bin also will be vented to the VSS and quench system to remove off-gases from the
melted material as it cools.
Details for Stage 1 Pre-Melt Process
In-Feed System
The existing 4-cubic yard feed bin that currently feeds the Tigard trommel will be used to feed MWP
onto the conveyor. The existing feed bin will provide enough capacity to run a pre-melt trial for
approximately 30 minutes at full design flow (1,000 Ib/hr).The trommel feed conveyor will be used to
deliver MWP to a new weigh belt.The weigh belt will provide a measure of total MWP flow into the
compactor.
Compactor
The compactor is a used Sanitech unit that uses an auger to compress the low density MWP. The
compression also removes air from the bulk material reducing the amount of oxygen introduced into the
DAM E.
DAME
The DAME will have a capacity of approximately 100-150 gallons and will have a custom top enclosure
that will seal the chamber to allow the unit to be operated under a slight negative pressure (-5 inch
W.C.). The top enclosure and slight negative pressure will allow off-gas to be removed and vented to the
quench/VSS/ECD systems.The DAME will be operated in a continuous or semi-continuous mode by
continually adding fresh MWP via the compactor, while discharging melted material via the discharge
screw into one of the mobile collection bins (MCB-1 and MCB-2).
Melt temperatures will be in the range 400-600 OF depending on the tests being performed and the type
of MWP. Oil temperatures in the heating jacket will be in the range 500-650 OF.
Discharge
In order to characterize the melt and test the ability of the DAME to discharge melted plastic material
under pressure, Stage 1 trial melts will discharge into enclosed mobile collection bins that will be filled,
swapped out, and left to cool while being vented to the VSS/Quench/ECD system. These bins will either
be a custom design or be custom-modified.
Hot Oil System
A hot oil system will be used to recirculate heated oil to the DAME.The heat transfer oil is heated
electrically and recirculates at a rate of 120 gpm. There will be an 80-gallon capacity thermal oil
expansion tank associated with the hot oil system.The expansion tank will be vented to atmosphere.
Sources of Air Emission
The three main potential points of emission from the pre-melt process are the DAME, the mobile
collection bin while it is being filled, and the mobile collection bin while it is disconnected from the
DAME and cooling. The DAME and mobile collection bins contain heated MWP that is known to off-gas,
vent moisture as steam and emit smoke in contact with air. Both the DAME and mobile collection bins
are vented under slight negative pressure to the quench tower(to remove any condensable gases) and
then onto the ECD at the back-end of the VSS (to separate the non-condensable gases). The compressed
in-feed plug (formed by the compactor) into the DAME is designed to allow a slight negative pressure to
be applied to the DAME and prevent external escape of gases.
Minor fugitive emissions may occur when a full mobile collection bin is disconnected from the DAME
and replaced with an empty collection bin.The full mobile collection bin will be reconnected to the
quench, VSS and ECD control system as soon as practicable to minimize the fugitive emission and allow
for capture of off-gas while the plastic completes cooling.These fugitive emissions will vent into the
building.
Emissions from the ECD are not expected to increase relative to existing permitted emission rates at the
Tigard facility for three reasons. First,the new pre-melt process will not fully pyrolize the plastic material
so the quantity of vapors coming from the DAME and collections bins should be less than if the plastic
were fully processed in the PRU.Secondly,the hourly and annual rates of plastic material sent through
the pre-melt process will be less than the maximum plastic processed through the PRU, so the amount
of plastic off-gassing will be less in the pre-melt process.Thirdly,the pre-melt process and PRU will not
be operated at the same time so emissions from the pre-melt process will not be in addition to
emissions from the PRU.
The thermal oil expansion tank is a categorically insignificant activity. Because of its small size and
nature of the heat transfer oil stored in the tank, emissions should be negligible.
The process flow diagram for the Stage 1 pre-melt process is provided in Attachment B.
1
Attachment B
Agilyx Tigard Stage 1 Pre-Melt Process Flow Diagram
Agilyx Tigard
Feed Pre-melt System Process Flow Diagram-Stage 1 To Atmosphere
---� Mixed Waste Plastic
Existing Thermal
-_ Off-gases Oxidizer(ECD)
--- ► Recirculating hot oil
Existing Quench/VSS
1
MWP i
Double-Arm
Feed Bin ----_. Compactor - — Mixer Mobile -
- Collection Bin Swapping
Extruder
(DAME)
(Filling) �----------------•
To Atmosphere
4i
Thermal Electric
Expansions------> Hot Oil
Tank Heater
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