Valve Magazine - Spring 2012

become much more efficient and reliable. A case in point is an energy company in Wyoming that had a solar panel riddled with bullet holes. In earlier times, that panel would not have functioned. Yet, in this case, they did not need to replace the panel until a significant portion of its surface area was damaged because of the latest generation of solar panels, which employs self-healing technology.

Today, battery racks can be as simple as a pair of marine-grade gel cells wired to deliver 24 volts direct current (VDC), or racks of batteries wired to deliver 48, 96 or 110 VDC. A typical electric motor operator would reach the limits of battery storage and energy transfer capacity very quickly. But if speed is not an issue, then trading horsepower for gear reduction would allow some very large valves and gates to be operated this way.

Most importantly today, however, is that users don’t have to be in the sun-belt to make solar work. Canada has many successful remote solar sites.

HIGH SPEED AND FORCE,
CRITICAL CONTROL

High speed, high force and critical control, which are all necessary requirements for dependable valve actuator operation, can be accomplished with an appropriate hydraulic operating system. By combining solar electric battery storage with hydraulic accumulator storage, very high operating forces and flexible speed control are possible. Full pipeline and station diagnostics are available as well.

Only a few years ago, communication
options in remote areas were very limit-
ed. Satellite receivers were expensive
and required a license; cellular towers
had not yet spanned the country; and
data capacity was limited. Radio sys-
tems were complicated and required
intensive maintenance. Today, however,
wireless technology covers even the
most remote parts of the country, and
most new pipelines are built with fiber-
optics for supervisory control and data
acquisition (SCADA) along their full
length. This allows the same level of
data acquisition and control at remote
sites as in a plant connected to the grid,
including both power and control redun-
dancies for critical operations.

CONTROLLING HYDRAULIC
SYSTEM LEAKS

An important factor when considering solar power for valve actuation applications is the potential for leaks. If the equipment is not properly designed for the environment, operating conditions, and pressure and temperature cycling, hydraulic systems can leak. In addition, the fluid itself needs attention. So-called “food-grade” hydraulic oils are readily available, and many can be rated for arctic or tropical conditions.

Hydraulic systems also are capable of great pressure and very high forces. More than a few pipeline gates with bent stems have been the unfortunate result of a lack of understanding about valve operation.

This is where a specialist engineering company with experience in remote solar-power applications comes into play. A valve automation center or even a company that specializes in general hydraulic equipment may not suffice in a remote situation.

Another potential pitfall is a segregated scope of supply. Buying an actuator from one vendor, a solar power supply from another and then having yet another company perform instrumentation could spell trouble. An integrated scope of supply from a source that maintains disciplines in-house and has years of field experience can stand up to the rigors of remote isolated duty.

EXAMPLES OF SUCCESS
In northern Argentina, 39 solar-pow-
ered actuators were field installed on an
existing 24-inch product pipeline’s
through-conduit gate valves. The actua-
tors were installed along with a new
pipeline SCADA system, which allows
the pipeline dispatcher to monitor pres-
sures and flow at each valve site and
close sectional block valves if needed.