The DeltaV system helps Thermex convert old tires to clean-burning
fuel
Discarded tires have accumulated throughout North America
in unsightly, mountainous quantities. In 1998, Thermex Technologies,
Inc., Montreal, developed a way to convert and cleanly recycle
the thermosetting rubber compounds that make up old car and
truck tires. Thermex selected the DeltaV digital automation system
because it could provide many of the features of a large,
traditional process control system at significantly lower
cost, said Thermex vice president and COO Normand Hupper.
Thermo-Sub, the packaged Thermex OEM process, gassifies the
old tires by a tightly controlled process that converts whole
tire carcasses into a continuous supply of clean burning,
gaseous, boiler fuel. The patented energy recovery system
offers great potential as a supplemental industrial energy
source for tire manufacturers, paper mills, chemical and cement
plants, waste treatment, and other industrial processes requiring
steam.
Fast Commissioning
As a venture capital OEM with limited resources, Thermex had
to quickly activate the Montreal demonstration plant. Configuring
the Thermo-Sub's controls and preparing the DeltaV workstation's
pages were among the most important assignments, and were
accomplished in just two months, Hupper reports.
Thermex chose the DeltaV system's easy and highly graphical
function-block diagram language for configuring most areas
of the process. What-you-see-is-what-executes logic presentation
saved time because the program could download directly into
a process controller without a compiling step. The logic runs
exactly as visualized, and as-built documentation was automatically
provided. The combination of features quickened checkout and
startup. Because the control system is not address-based like
a PLC, engineers could move tags between controllers without
modification. And because there is only one database, Thermex
eliminated the time and effort of preparing and mapping separate
PLC and OI databases.
DeltaV handles discretes volume
The DeltaV system economically handles large numbers
of discrete points in addition to analog channels. Even though
the chambers and boiler require substantial numbers of PID
loops and instrument inputs, the energy-recovery package as
a whole is 70% discrete -- an unusually high percentage in
a package, primarily due to the extensive materials handling
requirements.
The integrated automation eliminates customers' need for
highly trained staff operators to manually trim the process.
The process profile, including ramping, is always under close
control and gas output is more stable than can be practically
maintained by manual control. Boiler emissions are also constantly
monitored and carefully controlled. Full automation is also
essential because no two batches of tires have exactly the
same process characteristics.
Rigorous, documented emissions control
Automation is only one of Thermex's control requirements.
Boiler emissions and critical process variables must be recorded
because of public concern over toxic or polluting emissions
from waste-recycling facilities. Thermex and its customers
must be able to prove to EPA and other governing bodies that
they've kept emissions within allowable limits.
Remote Diagnostics
Modem communications between Thermex offices in Montreal and
customers anywhere in the world will provide support to Thermo-Sub
installations. The company will perform remote diagnostics,
troubleshoot, and recommend corrective action.
Flexibility Crucial
Because the pilot plant in Montreal is a research tool, engineers
are constantly making control system adjustments. When the
first European and US Thermo-Sub units are installed, they
may need to quickly adapt to unforeseen local conditions.
The DeltaV system's ease of use, flexibility, and speed in
making on-site control alterations are essential.
The DeltaV system also allows Thermex the option to add advanced
control functions like neural networks and fuzzy logic for
even more sophisticated control and smoother energy output.
Fast process automation payback
Hupper estimates a two-year investment payback for North American
installations, including avoided fuel costs, income from a
50 cent per tire tipping fee, and sales of residual steel
and carbon black. And with higher energy costs in Europe,
he says, payback there should be even faster.
back to top
|
