Chemical Technology April 2016

17 / 40

15
FOCUS ON CONTROL &AUTOMATION
Chemical Technology • April 2016
Babcock’s new flagship branch in Middel-
burg has been described as one of the most
advanced yellow-metal facilities of its kind,
and for good reason. The design team spent
several months planning the infrastructure
of the facility to ensure that every detail was
designed around Babcock’s specific require-
ments. All aspects of the new facility were
custom engineered with efficiency in mind,
from extra-large workshop bays to accom-
modate massive 150-tonne rigid trucks, to
a bespoke oil separation system to manage
the hydrocarbon water waste mix generated
by the facility.
Babcock is the exclusive distributor of
leading international brands and equipment
including Volvo Construction Equipment,
Terex Trucks, SDLG construction equipment,
Tadano mobile cranes and Winget concrete
handling machinery. The new branch in
Middelburg serves as a regional hub for
sales, parts, service and support and was
purpose-built to accommodate the full range
of construction equipment represented by
Babcock, including the mammoth TR100
trucks, the largest of the Terex rigid dump
truck range.
Requiring 138 litres of engine oil to be
replaced during a service, these trucks
alone call for an efficient used oil waste
management system. The facility gener-
ates approximately 4 000 litres of used oil
per month from servicing and maintaining
predominantly mining construction equip-
ment and trucks, as well as hydrocarbon
contaminated water from cleaning and
washing, so an efficient hydrocarbon waste
management system is critical to prevent
environmental oil contamination and to
manage hydrocarbon waste in a safe and
environmentally friendly manner.
“Due to the high levels of sediment pres-
ent on construction equipment, comprising
mostly clay and coal dust as well as the
usual oil, grease and hydraulic hydrocar-
bons, classic underground grease traps are
insufficient and unreliable. They are actually
an outdated design and an environmental
hazard in environments that have a high
sediment load in the waste water,” says
Michael de Weijer, Babcock’s Project Man-
ager for the new branch.
“Instead, the facility was designed with
this in mind, and all workshops and wash
bays drain into a common oil separation
system integrated into the building. All used
water that can contain oil, sand and coal
dust from the workshops, spray booths,
wash bays and boiler shop drain directly
into a subterranean system comprising a
common settling tank, an accumulation
sump and oil separator, located in the refuse
area,” explains de Weijer.
“As oil, coal and sediment combine with
water in the cleaning and servicing of this
equipment, high sediment loads can block
the drain pipes, so even the gradient of the
drainage system was increased to 4,5 % to
speed up the flow rate and reduce possible
sediment blockage. When the hydrocarbon
contaminated waste reaches the settling
tank, the flow rate reduces and the water-
borne sediments settle in a 1,25-metre-
deep chamber. The sediment-free water
and hydrocarbon waste is skimmed off the
surface of the settling tank by flowing over
a small dam wall into a second chamber
acting as a sump.
The sump is emptied by a simple com-
pressed air double-diaphragm pump
activated by limit switches and this water
hydrocarbon mix is then pumped into a
classic oil/water separator. Oil is trapped in
a central chamber in the separator while oil-
free water is discharged into the municipal
waste. The separated hydrocarbon waste
in the oil trap is pumped into one of three
integrated used oil tanks, which collectively
hold up to 7 500 l of oil. When all three tanks
are full, the site’s used oil is removed and
recycled by commercial used oil vendors. It
takes about two months for all three tanks
to fill up. An alarm has been installed for a
pending overflow warning condition, but if
there is a spill, the oil just goes back into
the sump,” says de Weijer.
Usually built underground, Babcock
specified that the settling tank, sump and
separator be installed above ground for
ease of access, servicing and inspection
should this be required, for conducting hy-
drocarbon contamination tests by municipal
authorities.
To avoid an overload of water entering
the oil/water separator which has a design
capacity of 2 000 l/hr, all non-hydrocarbon
contaminated storm water is discharged to
the site’s storm water system.
Another bespoke feature at the facility
is an integrated piped lubrication system
that pipes the five most common oils and
compressed air directly to the workshop
bays and returns the used oil to the used
oil storage tanks.
For more information contact:
Michael de Weijer at:
Babcock custom engineers hydrocarbon waste management system
PETROCHEMICALS