The Fiber Accelerator - Pulp and Paper Canada

MACHINE DESIGN
Gain by operating Fiber Accelerator instead of pressure cyclone
or steam loss by blow line dilution (based on a real case)
Steam in blow line
q 1
20 t/h
Pressure 4 bar(a)
enthalpy 2738 kJ/kg
q 2
Blowline dilution 5 l/s
18,0 t/h
temp 35 °C
enthalpy 147,0 kJ/kg
Steam loss 3,8 t/h
Energy cost (operating cost Fiber accelarator)
q 3
16,2 t/h
q 4
enthalpy 602 kJ/kg
Specific energy consumption 6 KWh/ton, FA1000/1100
Pulp production 25 ton/h
Energy price 0,3 SEK/kWh
Operating time 350 days/year 378000 SEK/years
Energy saving/recover
Steam gain 3,8 t/h
Live steam cost 75 SEK/t 2418148 SEK/year
Generated steam Fiber accelerator
1260 t/year 94500 SEK/year
Fibre gain
Fibre loss pressure cyclone 5 kg/ton
Fibre loss FA 0,5 kg/ton
Wood price 300 SEK/ton 283500 SEK/year
Energy loss (energy used on loss fibre)
Spec. energy pulp 1100 KWh/ton
Energy price 300 SEK/ton steam generated (1MW=1ton steam)
Power on lost fibre 124 KW 233888 SEK/year
Cost 3788000 SEK/year Savings 3030036 SEK/year
Gain 2652036 SEK/year
FIG. 19. Example of energy balance and cost calculation fir a typical TMP system
to be equipped with Fiber Accelerator.
Since the start-up, almost two years ago, the Fiber Accelerator
has practically been in continuous operation with 100%
availability.
INSTALLATION OF THE
FA-1100 UNIT AT ORTVIKEN
A new FA-1100 Fiber Accelerator was installed after the primary
refiner on a new double-disc TMP line in the Ortviken mill of
the SCA Company during the fall of 2001. This line was started
up at the end of October 2001. Figures 15 and 16 shows photographs
of the installation.
And details of the operating parameters are provided in
Fig. 17.
EXPERIENCE WITH THE
FA-1100 UNIT AT ORTVIKEN
Since the presentation of the Fiber Accelerator at the PAPTAC
Annual Meeting 2002, the FA-1100 Unit at Ortviken has been
equipped with a “Frequency Control” Variable Speed Drive and
data has been collected at various speed.
The diagram, Fig. 18, shows the fibre carry-over in grams per
ton of pulp produced at various speeds of rotation and at two
different levels of pulp consistency in the blow-line.
When these data were collected the pulping capacity was 285
air-dried tonnes/day (adt/d), pulp freeness in the blow-line at
150 to 170 mL CSF and the steam flow 22 t/h.
The maximum capacity, so far, of this Unit at Ortviken has
been 355 adt/d with a steam flow of 27.5 t/h.
CONCLUSION
For each individual application a calculation should be made to
determine the optimal operating parameters with regard to
steam and pulp capacity, blow-line velocity, size of the Fiber
Accelerator unit, speed of rotation and motor size. It is also advisable
to make an energy balance and a cost calculation. Such a calculation
for a typical existing TMP system is shown in Fig. 19.
In this case the calculation clearly illustrates the energy losses
caused by blow-line dilution. In the upper section of the figure,
the calculated steam loss due to the dilution was 3.8 t/h.
The pulp production capacity of the plant was 25 t/h, the steam
flow from the refiner was 20 t/h and in this case the blow-line
dilution was 5 L/s, which is a rather normal figure.
The three lower sections shown in this figure deal with the
savings achieved by using a Fiber Accelerator instead of the pressure
cyclone. The first section shows the energy cost for running
the Fiber Accelerator with the specific energy consumption 6
kWh/t pulp. The middle section demonstrates the energy gain
by avoiding dilution, the gain from steam generated by the energy
input in the Fiber Accelerator and the gain from wood cost
due to reduced fibre losses with the Fiber Accelerator.
In this case there is no recovery of carried-over fibres and the
fibre loss is conservatively calculated at 5 kg/t pulp for the pressure
cyclone, and 500 g/t for the Fiber Accelerator. The third
section of the calculation shows the energy loss due to the fibres
which are lost from the system. The cost, the accrued savings
and the financial gain achieved by using the Fiber Accelerator
are summarised on the right side of the diagram. These relative
figures are illustrative but for comparison it may be noted that
the exchange rate at the time that this paper was prepared was
6.70 Swedish Kronor (SEK) to 1.00 Canadian Dollar.
In summary, the Fiber Accelerator is a new efficient device
capable of replacing conventional equipment for the effective
separation of steam and fibre in TMP and CTMP plants. Two
sizes are available, designed to meet the capacity requirements
of most existing TMP plants today. From the operating experience
gained to date, it is evident that the Fiber Accelerator will
solve many of the problems currently associated with energy
recovery. Some of the advantages are:
• Very little fibre carry-over, no fouling of reboiler, minimum
loss of fibres;
• No build-up of fibres in the system;
• Uniform feed through, undisturbed and consistent process;
• Short fibre retention time at high temperature, minimum of
fibre darkening;
• Low pressure drop, optimal energy recovery;
• No requirement for blow-line dilution and thus no energy loss;
• Immediate start-up of the system with heat recovery; and
• No requirement for a scrubber.
Résumé: La présente communication porte sur le Fiber Accelerator, un
nouveau dispositif pouvant remplacer les épurateurs sous pression dans les
circuits de PTM, afin de réduire la teneur en fibres de la vapeur produite par
les raffineurs et acheminée au récupérateur de chaleur. À l’opposé de l’épurateur
sous pression, ce nouveau dispositif permet à la pâte de circuler à une
vitesse supérieure à celle de la conduite de décharge et réduit considérablement
la quantité de fibres transportées au récupérateur de chaleur.
Les données opérationnelles d’un prototype en usine ainsi que d’une unité
commerciale installée en permanence font l’objet de discussion.
Reference: RYRBERG, K.-G., OBITZ, L., ENGLUND, R. The Fiber
Accelerator: A new device for energy recovery in TMP and CTMP
plants. Pulp & Paper Canada 105(2): T26-29 (February, 2004). Paper presented
at the 88th Annual Meeting in Montreal, QC, on January 28 to
31, 2002. Not to be reproduced without permission of PAPTAC.
Manuscript received on November 29, 2001. Revised manuscript
approved for publication by the Review Panel on December 4, 2002.
Keywords: THERMOMECHANICAL PULPING, MACHINE DE-
SIGN, STEAM, HEAT RECOVERY, FIBERS, ENTRAINMENT, VELOCI-
TY, ACCELERATION, BLOWLINE REFINING.
Pulp & Paper Canada T 29 105:2 (2004) ❘❘❘ 27