Small Decentralized Hydropower Program National ... - Cd3wd.com

corriente lo llene de pedregullo durante el period0 de
la creciente.
La regla es simplemente suministrar un area de
escape mucho mayor que lo que parezca necesario en
un principio. Se debe dirigir la zanja de la descarga
agua abajo por una corta distancia antes de que se
una a la corriente principal.
Historia de Algunos Casos
Una turbina Francis de 25 kW fu& instalada en un
lugar remoto en un pais de1 norte de Africa para fun-
cionamiento sin ninguna conecci6n a ninguna otra
fuente de generacibn. La unidad fu6 colocada sobre
la corriente, oper6 bien por aproximadamente cinco
meses y entonces una gran tormenta caus6 el creci-
miento de1 agua en la corriente de donde se tomaba
el agua, por medio de un canal de 600 metros a una
antecamara de madera y cafietias de presi6n de
acero, para la turbina. Me encontraba yo en el pais y
me pidieron que inspeccionara la turbina sin d&rseme
descripci6n de1 dtio, ~610 me dijeron que no
funcionaba.
Al llegar a la villa, donde no habia habido luz desdz
varios meses atras, observe que la salida era casi
paralel;l. a! flujo de corriente principal. El canal de
600 metros estaba parcialmente lleno de pedregullo
casi a todo lo largo. La rejilla protectora contra
basura se habia derrumbado dejando paso a una ca-
rnionada de grava que descend% por la ctieria
depresi6n a la turbina. Al pie de la caiietia de
presidjn, un coda de radio largo alimentaba el agua (y
la grava) directamente en la caja de las compuertas y
de1 rotor. La mkquina estaba desttida.
Solucih. Rediseiiar la salida a 90 grados, in&alar
las piletas de sedimentaci6n a cada extremo de1
canal, mantene: limpia la rejilla de protecci6n contra
basura y reforzar 10s soportes.
Una turbina vertical a helice de 100 kW habia fun-
cionado bien por aproximadamente cinco ties im-
pulsando a un generador con eje horizontal a trav&
de una caja de engranajes de angulo 3:l. La caja
engranajes habia sufrido una falla. El fabricante
habia suministrado piezas de repuesto para recon-
strucci6n en el campo, pagando el costo. Como una
semana despu& de haber comenzado a funcionar, la
caja de engranajes producia ta.1 ruido que el operador
decidid cerrar el sistema.
Al llegar al lugar encontre que la caja de engranaje
habia sufrido dafio que ya no se podia reparar. La
turbina estaba en una caja de presidn de 9 pies de
week after start-up the gear box became so noisy
that the operator shut the system down.
Upon arrival at the site, I found the gear box to
be damaged beyond repair. The turbine was in a
9 foot diameter pressure case with a single side
inlet. The client was a mining company with
machine-shop facilities. Penstock was 5 feet in
diameter, nearly vertical and supported on con-
crete piers crossed by two 24 inch l-beams on
about 14 foot spans.
I set up dial indicators on the hub of the gear
box, reading on the hub of the turbine. Next I
blocked rotation of the turbine and filled the
penstock and pressure casing. The turbine hub
moved 105 thousandths of an inch with respect
to the gear hub. The entire system lacked rigidity.
Solution. I ordered a thrustit bearing for the
generator and mounted it vertically, installed
Timken roller tail-shaft bearing on turbine shaft
and installed 15G H.P. industrial “Vee-Belt” drive
from spares client had on hand for Ball-Mill
drives. Unit has now been in operation for a little
over three years without further trouble.
A comment: It is probable that this system
col:ld have been stiffened to control the deflec-
tions that were damaging the gear box. The time
element spelled out the solution that was used.
The cause of the damage was the failure to pro-
vide adequated support for the penstock.
The client was a large U.S. paper company,
engaged in generating his own power with a pair
of vertical shaft Kaplan turbines. During the
period of adequate water, he ran both units and
generated very little steam electricity. During the
summertime, he ran one unit only and shut the
other one down. About three years after start-up,
with one unit running, lightning struck the power
line between the power plant and the paper mill.
Damage was confined to the spider and keys
that attached the umbrella-type generator to the
vertical turbine shaft. The spare unit was running
when I arrived at the site.
Solution. The spider had to be replaced and it
took the rest of the summer. By autumn both
were running and ran throughout the winter.
Calculations made with respect to the failed
spider revealed no design weaknesses. We could
see that the forces generated by the lightning
could reoccur. We recommended that both units
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