THE FUTURE OF COMPRESSION SYSTEMS

Harry Miller, Director for Emerging Technologies at Dresser-Rand discusses integrated compression systems, magnetic bearings and waste heat recovery.

What are some recent innovations in compressor systems?

The Datum ICS (Integrated Compressor System) incorporates centrifugal separator technology to permit simultaneous separation of liquids from a gas stream and compression of the dry saturated gas. All valves, controls and intercoolers are in one compact package. The heart of the system is a Datum compressor, modified to include a rotating separator in front of the first stage centrifugal impeller. It is driven by a direct-connected, high-speed electric motor with magnetic bearings, all hermetically sealed.

What is it used for?

Our original thought for the ICS was for offshore production on fixed platforms and floating production, storage and offloading (FPSO) vessels as these platforms usually do not have much space for additional compression or separation equipment. However, it is also suitable for a range of onshore, offshore and subsea applications.

Say, for example, you have changing offshore field conditions, such as declining pressure. As a result, the compressor inlet volume increases such that it needs more stages and has to be rerated. However, rerating the separator often is not feasible on an FPSO, because they are so large and space is at a premium.

The design of the ICS overcomes this space problem by harnessing centrifugal force in a rotating separator to accomplish separation in a compact and efficient way. This typically results in a 50% reduction in footprint and weight.

For example, Petrobras had an offshore installation where a rerate of the compressors could not meet the flow at the required pressure, so the ICS was the only compact solution. Petrobras has installed one of these systems, which is sized approximately 5 meters by 4 meters by 6 meters. We anticipate that this will become the configuration of choice in the future to reduce size and footprint, increase reliability and reduce maintenance.

Any other clients you care to comment upon?

We are marinizing the ICS in a joint development project with Statoil. This involves testing in a giant water tank in our Olean, New York facility. This testing is important as the energy industry is keenly focused on subsea compression.

The purpose is to raise the technical readiness level of subsea compression and gain operating experience in conditions as similar to the field environment as possible. Subsea processing is growing and oil companies want to migrate from topside as much to subsea as possible to reduce liability, costs and topside risks, such as severe weather conditions. However, because we are dealing with a conservative industry, the transition is not expected to occur overnight.

Tell us about magnetic bearings.

We acquired our magnetic bearing technology through our acquisition of Synchrony, Inc. Synchrony created a higher tech design that costs less than the competition. Several years ago, we identified the strategic importance of being in a position to offer oil-free solutions in high-speed rotating equipment applications.

The overall value proposition for eliminating auxiliary oil systems centers around three principles:

• The resulting reduced footprint and weight in platform and FPSO applications generate overall CAPEX savings in the construction phase

• Oil-lubricated bearings in subsea applications are neither practical nor reliable

• The presence of lubrication oil in compressor and steam turbine applications is environmentally unfriendly, as it generally needs to be reconditioned and, ultimately, discarded after mixing with process gas or steam

What are you developing in waste energy recovery systems?

We have an equity position in Echogen Power Systems of Akron, Ohio. This system uses a supercritical CO2 working fluid to convert waste heat into power without creating new emissions, and does it more efficiently than existing organic Rankine cycle (ORC) technologies.

Since the technology recaptures heat that was previously released into the atmosphere, the cost per unit of electricity decreases. Currently, a 7.5 MW unit is undergoing testing. The equipment needs a turbine-driven generator, and a centrifugal CO2 pump. There is also an opportunity for us to develop our own turbomachinery to use with this process.

Echogen has been more focused on industrial sector waste heat recovery. Our interest is for oil and gas applications.

What kind of oil and gas applications are you looking at?

Most oil and gas compressors do not have waste heat recovery to supplement power generation on the platform. Waste heat recovery would enable them to generate more power on the platform. For example, a GE LM2500 gas turbine provides 30 MW of power, and we think we can recover another 6 to 8 MW. Those extra MW would be much cheaper than trying to generate them by adding turbines.

How about the emissions side?

This is a great way to convert waste heat into power without creating new emissions. It is accomplished by adding a heat exchanger to heat the CO2. As this is done in a closed loop, there are no emissions. Yet you gain more power.

What else are you developing?

The Dresser-Rand HydroAir ocean wave power generation turbine uses oscillating water column (OWC) technology to convert surface wave motion into electrical energy.

Ramgen supersonic compression technology is envisioned to be capable of high compression ratios (10:1) for medium- to-high molecular weight applications such as CO2 compression applications in a compact, single-stage package.

The Dresser-Rand Vectra power turbine family can be matched to the GE LM2500, the LM2500+ and the LM2500+G4 aeroderivative gas turbine engines for both mechanical drive and electric power generation applications.