CCI & DRAG® Handle the Pressure of Earth-Friendly Technology

For a moment, imagine your day without your alarm clock, coffeemaker, computer, telephone or television. Imagine the chaos that would ensue without electronic medical equipment, communications systems, or trafic lights. In our modern world, we rely on electricity nearly every minute of every day. And every day, we consume more and more of this resource, driving demand ever higher.

As the world faces an energy-production dilemma, Geodynamics Ltd. is one company making efforts to bring us into a new age of clean, renewable energy. One source of such energy is hot fractured rock (HFR)geothermal energy, the only known source of renewable energy with the capacity to carry large base loads.

HFR geothermal projects are currently underway in France, Switzerland, Germany, California, and Japan. Now, Australia is joining the quest to develop renewable energy as Geodynamics carries out its Habanero #1 and Habanero #2 projects in Innaminka. And CCI is getting on board as well, as its severe service control valve technology will play a critical role in this earth-friendly endeavor.

Geodynamics’ projects entail drilled wells for HFR geothermal energy at a site in Cooper Creek which, at a depth of 3.1 miles (5 km) underground, is the hottest place on earth outside volcanic centers. The Habanero #1 well was completed in October 2003 and, at a depth of 2.75 miles (4.42 km), it is one of the deepest wells ever drilled onshore Australia. The Habanero #2 well, completed in December 2004, was drilled 2.7 miles (4.35 km) deep.

Deep within these wells lie special high heat-producing granites; the heat inside these granites is trapped by overlaying rocks, which act as an insulator. Heat is extracted by pumping high-pressure water down and circulating it through these rocks in an engineered underground reservoir that acts like a heat exchanger.

Water returning from the underground heat exchanger is extremely hot - greater than 480ºF (250ºC). At the surface after pressure reduction, it interacts with another heat exchanger in closed loops (to keep the water source for the turbine clean for improved reliability), where steam is generated at a small turbine. The primary water exiting the heat exchanger is then re-injected into the ground to pick up more heat. Approximately 275 megawatts of heat will be available through this process for at least 30 years; the energy available from this source is generated at a small turbine. The primary water exiting the heat exchanger is then re-injected into the ground to pick up more heat. Approximately 275 megawatts of heat will be available through this process for at least 30 years; the energy available is equivalent to burning 50 billion barrels of oil. The process is cost effective, too – the estimated cost is approximately $30 per megawatt hour, about half the cost of generating energy through oil or gas.

With such a unique process, those at the Geodynamics site knew they needed a unique production choke valve capable of handling extremely high temperatures and pressure drops. The site engineer knew of DRAG®’s reputation for handling high pressure drops and chose CCI based on its advanced engineering capabilities.

To handle the severe pressure drop inherent in the process, CCI designed its valve with proven DRAG® technology, making this choke the first-ever DRAG® valve selected for this duty. The valve will handle superheated water that is forced back up through the choke that modulates the flow to the closed-loop heat exchanger. CCI’s DRAG® disk stack controls flowing velocities through the valve trim by forcing the process fluid to follow a tortuous path of right-angle turns. The resistance to flow provided by these turns limits the trim exit velocity to a safe level, regardless of the pressure drop. The flow passages also expand in size to accommodate flashing and reduce discharge velocities for outstanding control.

The unique geothermal process also called for carefully selected valve material to endure such extreme conditions. First, the DRAG® trim had to be able to withstand solid components picked up from the injected water, so CCI offered tungsten carbide for the disk stack and valve trim. Fifty to 500 times more erosion resistant than conventional metals, this trim will handle the granite particulates and other entrained solids in the fluid. Additionally, to accommodate the intense high pressure, temperature, and corrosive fluids involved in the process, CCI built the valve body out of duplex stainless steel, a high-strength material that will resist stress corrosion cracking.

The choke valve wasn’t alone in handling pressure during the course of this project. Delivery was critical, and CCI stepped it up to get the valve to the customer by early November 2004 so that Geodynamics could stick to its project time line.

Thrilled with this expedited delivery, Geodynamics was also happy to witness the outstanding performance of its DRAG® choke valve. Since its installation, the customized valve has been operating without a hitch, taking on extreme temperatures and pressure drops like a champ.

This spring, the first steam was produced at the Geodynamics site, making for an exciting occasion that even captured media attention as five major Australian television networks gathered in Cooper Creek to capture the moment. CCI is proud that its DRAG® production choke valve played a critical role in the success of this ground-breaking project.

Published in SOLUTIONS Summer 2005