Richard Stover

Richard Stover, Ph.D., Chief Technical Officer Born December 15, 1962 in Ravenna, Ohio Raised in Glen Ellyn, Illinois

Richard Stover is one of the individuals who perfected the PX-220 that has become the basis for some of the largest SWRO plants being designed today, servicing train sizes up to 25,000 cubic meters per day of permeate capacity.

It is greatly involved in seawater desalination which promotes energy recovery thus promoting to a better global welfare.

Biography

Studied chemical engineering at the University of Texas at Austin 1983 – 1986. Graduated with bachelor’s degree. Worked for 3M Company in Minnesota 1986 - 1990 as a process and chemical engineer. Responsible for product delivery, reliability, and production at a videotape manufacturing facility. Used design-of-experiments and response-surface analysis to optimize process settings and chemical formulations. Applied statistical process control to optimize product quality and reduce waste.

Travelled 10,000 miles by bicycle in Southern Europe 1990 - 1991.

Studied chemical engineering at the University of California at Berkeley 1991 – 1996. Dissertation: "Bubble Dynamics in Electrolytic Gas Evolution” (Electrochemical Engineering) with Charles Tobias and Morton Denn. Devised an optical-laser technique to record fluid dynamics during hydrolysis. Experimented with surface tension, viscosity, electrode polarity, and bubble size. Simulated experiments with a finite-difference fluid-flow model. Graduated with Ph.D.

Worked for IBM Corporation in San Jose from 1996 – 1998 as a process development engineer. Led a manufacturing engineering team in developing and implementing a process for reducing friction and contamination in advanced computer hard drives. Discovered, demonstrated, and patented a hard-drive component design feature to increase product reliability. Worked for LFR Levine Fricke in Emeryville California 1998 – 2002 as a chemical engineering and environmental consultant. Designed and implemented wastewater treatment plants using chemical, electrolytic or membrane separation processes. Ran pilot studies, supervised construction for all trades, conducted startup, and provided training and operations and maintenance support.

Joined Energy Recovery Inc. in 2002 to develop and launch the PX-220, which has since become the leading energy recovery device in seawater desalination. Dr. Stover’s numerous publications and achievements have earned him international recognition as an expert in energy recovery and process optimization in reverse osmosis systems. He holds responsibility for technical product-support services, strategic positioning of PX® technology, and managing and expanding ERI’s intellectual property holdings. In addition, in his current role as Vice President of Sales, he is responsible for strategic growth and risk management. Dr. Stover was a co-recipient of the European Desalination Society’s 2006 Sidney Loeb award for outstanding innovation. Married since 1996 with 2 children.

Project Involvements

Development of Isobaric Energy Recovery Devices

Mr. Stover has contributed a lot in the study and development of Isobaric ERD’s or Energy Recovery Devices having to explain the details by which constitutes the process of SWRO (Seawater Reverse Osmosis) in relation to Energy Recovery. Richard Stover detailed the processes involved within SWRO systems which was overviewed from its Designs up to its Operations considering technical factors such as its energy consumption, and membrane performance along with the processes involved within each stage of the SWRO like overflush and mixing. For the Operations, factors to consider were from Energy and Flux variation to its maintenance, and device life which concluded that Isobaric ERDs offer significant benefits to SWRO plant designers and operators. These include unlimited capacity, reduced high-pressure pump costs, high efficiency and operational flexibility. Among the commercially available isobaric ERDs, the PX Pressure Exchanger isobaric ERD provides the following advantages:

•minimal simple controls •fail-safe operation •maintenance free operation •corrosion avoidance •low vibration •long life

These design and operational advantages have not only made isobaric ERDs the best choice for energy recovery in SWRO systems, they have also enabled the tremendous growth and success of SWRO for desalination applications.

The 200,000 m3/day Hamma Seawater Desalination Plant – Largest Single-Train SWRO Capacity in the World and Alternative to Pressure Center Design

Richard Stover was again involved in the Hamma Seawater Desalination Plant Project. This project involves the pumping system, train size and energy recovery system configuration of the GE Infrastructure (Ionics) project in Hamma, Algeria (Hamma). The project is the first private reverse osmosis potable water project in Algeria and the largest membrane desalination plant in Africa.

The Hamma project is an SWRO plant capable of continuously producing 200,000 cubic meters of permeate per day (m3/d). The Hamma plant is intended to supply 25% of Algeria’s capital city’s population with desperately needed drinking water. The project is the first private reverse osmosis potable water project in Algeria and the largest membrane desalination plant in Africa.

The Hamma plant was designed for both high capacity and minimum operating cost. Because pumps consume most of the energy supplied to the plant, it was essential that they be designed for high operating efficiency. As described by the Hydraulic Institute, larger centrifugal pumps are generally more efficient than smaller pumps, and the peak efficiency for very large centrifugal pumps is about 89% (2). The HP pumps selected for the Hamma plant operate at 1,084 m3/hr and approximately 88% efficiency, close to the theoretical maximum for the centrifugal pumps and notably high for high-head service. The booster pumps are also large, operating at 1,351 m3/hr and 89% pump efficiency.

An alternative to large trains is to feed multiple smaller trains with the same HP pump in a process configuration known a pressure center design. One of the advantages of this design is that larger, more efficient HP pumps can be used than if the individual trains were supplied separately.

An advantage of Hamma’s dedicated high pressure pumps is that each train can be operated independently, thereby facilitating relatively easy startup, shutdown and optimization of membrane recovery rate.

In a SWRO system equipped with PX Pressure Exchanger energy recovery devices, the membrane reject is directed to the membrane feed (through the PX devices and booster pump).

Perth Seawater Desalination Plant

Richard Stover was involved in the design and operation of the Perth plant that is presented as a standard for seawater reverse osmosis plants and a model for sustainable water production from the sea.

The plant utilizes reverse osmosis; a water desalination process widely used around the world. The osmotic pressure of a salt water solution is overcome with hydraulic pressure, forcing nearly pure water through a semipermeable membrane. In seawater reverse osmosis (SWRO) systems, an operating pressure of between 60 and 70 bar is typically required. Even at these pressures, a maximum of approximately 50% of the available pure water can be extracted before the osmotic pressure of the concentrate makes additional extraction too expensive. The rejected concentrate leaves the process at nearly the same pressure as the membrane feed pressure.

As a result of the innovative design and successful performance of the performance of the plant, the PDSP was recognized as the Desalination Plant of the Year in 2007 by Global Water Intelligence. It has been heralded as a landmark in the development of the Australian water industry. It is regarded as a world-leading model for future sustainable seawater desalination plants globally.

Typically 50 to 75% of the energy consumed by an SWRO plant is used to drive the motors of the high-pressure pumps of the first pass. (Mickols et.al. 2005) Isobaric ERDs reduce the load on these pumps using the energy contained in the first-pass membrane reject stream.

The importance of isobaric ERDs for reduction of energy requirements and associated environmental impacts in SWRO technology received international recognition by desalination operators and users. The Energy Recovery, Inc. PX Pressure Exchanger® device was awarded Environmental Contribution of the Year in 2007.The energy requirements for modern SWRO were compared to those of conventional sources of water supply in Southern California by the Affordable Desalination Collaboration. Energy consumption for a small SWRO plant was measured as 3.1 kWh/m3 compared to the power required to convey surface water to Los Angeles: about 2.9 kWh/m3. However, regardless of the energy required, additional surface water capacity to meet increased demand in Southern California is simply not available. Therefore, the cost of seawater desalination was instead compared to the cost of alternative means of new supply. For this comparison, the cost of a 190 mega-liter per day plant with conveyance piping was compared to the cost of a comparable recycled water facility. The SWRO cost range was 0.63 – 0.74 USD/m3 compared to 0.81 USD/m3 for recycled water. (Dundorf et.al. 2007) In addition to the cost advantage of SWRO, other factors make it preferable to large-scale recycling including the unlimited availability of seawater, legal limits on use of recycled effluent and the challenge of overcoming the public’s aversion to “toilet-to-tap” reclaimed water. (Dingfelder 2004)

In addition to energy consumption, other potential environmental impacts to consider and manage carefully are concentrate and solids disposal. The discharge products from an SWRO process can include the seawater intake screen washings, clarified backwash effluent from the media filtration plant, reverse osmosis plant seawater concentrate stream, neutralized RO plant chemical cleaning wastewater and RO plant flushing water.

Significant concern has been raised about the potential environmental impact of concentrate discharges from desalination facilities. However, the majority of the known impacts are from thermal (distillation) facilities from which copper and other metals leached from the process are discharged. Membrane desalination facilities, which use significantly less metal and operate at much lower temperatures, do not cause such impacts. To meet the strict environmental requirements for discharge into Cockburn Sound, the seawater concentrate is returned from the PDSP 470 meters into the ocean via a 40-port diffuser at the end of the discharge pipeline. The velocity of the discharge through is 4 m/s through nozzles spaced at five meter intervals to ensure total mixing of seawater concentrate within 50 meters of each side of the pipeline. Instruments that continuously monitor plant discharges automatically shut down the process in the event of an exceedance. In addition, the intake is designed for low-flow to effectively limit uptake of marine life. (Crisp et.al. 2007)

References

Seawater Reverse Osmosis with Isobaric Energy Recovery Devices
The 200,000 m3 per day Hamma Seawater Desalination Plant
ENVIRONMENTALLY SOUND DESALINATION AT THE PERTH SEAWATER DESALINATION PLANT
ERI SALES & MARKETING TEAM
Desalination company Energy Recovery Inc. plans IPO SWRO Process Simulator