Mechanical Technology March 2015

Mechanical Technology — March 2015

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Power, energy and energy management

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he Zest WEG Group, through

subsidiary company Zest Energy

and its technology providers has

successfully completed a bench-

mark steam turbo generator set contract

at Mondi Richards Bay that showcases

the Group’s value addition, innovation

and customer focus. The original contract

was awarded in May 2012 and partially

handed over in December 2013, with

final hand over in March 2014. This

contract has been followed by a five year

Long Term Service Agreement (LTSA),

where Zest Energy will be responsible

for the overall maintenance of the steam

turbo generator set.

Coenraad Vrey, managing director at

Zest Energy, explains: “Essentially for

the duration of the 24-month warranty

period we have had to guarantee a mini-

mum 98% availability, which has been

linked to the execution of the LTSA. This

means Zest Energy will co-ordinate the

actual servicing under the supervision of

our technology provider’s international

service technicians. The agreement also

includes the supply of all the necessary

replacement parts and consumables.”

The scope of work included the de-

sign, manufacture and delivery as well as

complete installation and commissioning

of the steam turbo generator set and as-

sociated equipment. Original equipment

manufacturer (OEM) supervision services

were also provided during installation and

commissioning, with 24/7 on call sup-

port for a period of four weeks following

handover. The flagship project achieved a

number of records: the largest ever steam

turbine manufactured by technology

provider TGM Turbinas. “Not only was

this the first project to utilise a combina-

tion of a TGM turbine with a WEG EM

alternator, it was also a first reference for

both equipment manufacturers in South

Africa,” Vrey says.

“Throughout the execution of this

project, the Zest WEG Group has proved

its ability to be involved in large scale

projects, not only from a standalone prod-

uct supply perspective, but also from an

integrated solutions point of view. This is

an important achievement that will drive

sustainable growth within the Group,”

says Alastair Gerrard, general manager

at Zest Energy.

Zest Energy supplied the turbo genera-

tor set equipment and took the overall

lead on the package, which included

steam technology from TGM Turbinas

of Brazil and generator technology from

WEG Electric Machinery of the United

States. Local subcontractor TGS (Turbine

Generator Services) undertook the me-

chanical installation portion of the scope.

Bosch Projects was appointed by Mondi

as the official engineering, procurement

and construction management (EPCM)

contractor on the project. However, the

steam turbo generator set was not only

the system supplied by the Zest WEG

Group to Mondi for this project.

Zest WEG Group power division sup-

plied two 132 kV/11 kV, 35/50 MVA

ONAF power transformers; two

11 kV/550 V, 2.5 MVA transformers;

one 11 kV/400 V, 1 MVA transformer;

and an 11 kV, 300 A for 10s NEC/NER

(neutral earthing compensator/resistor)

for protection against earth faults. Zest

WEG Group motors division supplied

two 1.2 MW, two pole 11 kV compres-

sor motors and two 560 kW, 12 pole

525 V booster pump motors, while Zest

WEG Group subsidiary, EnI Electrical,

completed the Mondi upgrade project

on the electrical, instrumentation and

control installation side.

Mondi already had a 38 MW extrac-

tion back pressure steam turbine and a

34.3 MW extraction condensing steam

turbine and required a new 48 MW

multi-extraction condensing steam

turbine to take up the additional high

pressure steam from the plant at full

load. The power generated is used on

site with the excess being exported to

the national grid.

Zest Energy has applied its experience in electrical infrastructure, substations

and power generation to install a 48 MW steam turbo generator set for Mondi

in Richards Bay, with all the electrical integration scope carried out inhouse.”

Several firsts for Mondi’s

48 MW cogen plant

The beginning of 2013 saw the design

and engineering phase of the project

under full swing, with close scrutiny of

the finer design details to ensure that no

crucial element had been overlooked.

Major long lead items such as the turbine

casings and forged rotor shaft had al-

ready been delivered to turbine manufac-

turer TGM Turbinas, while WEG Electric

Machinery clocked up similar progress.

The Zest Energy project team was

then faced with the formidable task of

transporting the completely manufac-

tured and assembled pieces of equipment

to their final destination in Richards Bay,

a task complicated by weather condi-

tions and road transport restrictions.

The process was finally completed in

August 2013.

Once on site, professional rigging

sub-contractor Lovemore Brothers, under

the supervision of TGS, was tasked with

lifting and positioning the equipment in