StarDesal

TM

Technology Description: 

  • Cascade Water Solutions LLC was organized in July 2017 around the patents and working knowledge of Mark Holtzapple at Texas A&M who has developed the StarDesal™ process for recovering freshwater from oilfield brine, brackish and salt water with concentrations up to 260,000 ppm. 

  • The equipment is in a trailer-mounted container and delivered to the oilfield site where water is recovered from the brine using vapor-compression distillation.  During World War II, this robust desalination technology was used to desalinate seawater on ships, so it is well proven.

  • As shown in the adjacent figure, saltwater is pumped and then preheated in a sensible heat exchanger.  Next, this hot salt water enters a latent heat exchanger where water evaporates, leaving concentrated salt behind.  The water vapors above the salt solution are removed and compressed with a StarRotor™ compressor to form high-pressure, high-temperature steam, which enters the other side of the latent heat exchanger.  The steam is hotter than the salt water, so it transfers heat from the steam to the salt water; consequently, the steam condenses forming distilled water.  The boiling salt solution is so concentrated that salt precipitates and is recovered.  The heat in the latent heat exchanger is recycled repeatedly.  The primary energy input is the shaft work needed to drive the StarRotor™ compressor.  Compared to traditional evaporation methods, vapor compression is very energy efficient.

StarDesal Competitive Advantages: 

The following are advantages of the StarDesal™ system:

  • EfficientStarRotor™ compressors are well suited for vapor-compression distillation.  As shown in the adjacent figure, StarRotor™ compressors are exceptionally efficient.    

  • ScalableStarRotor™ compressors are efficient, even at small scale. This important feature allows the vapor-compression system to be operated at a small scale in a distributed manner.  In contrast, other distillation approaches require large centralized plants.

  • DistributedBecause StarDesal™ can operate efficiently at small scale, it can be employed in a distributed manner at the wellsite.  In contrast, to be efficient, other distillation technologies must operate in large centralized plants that require oilfield brine to be transported long distances typically by trucks.

 

  • RobustThe heat exchangers are robust and have successfully evaporated every oilfield brine that has been tested (Marcellus, Woodford, Haynesville, Fayetteville, and Bryan, TX.) 

 

  • PortableThe equipment is in a trailer-mounted container and delivered to the oil well, thus minimizing the transport of water via trucks or pipelines. 

  • AdaptableStarDesal™ units will be produced in three capacities: 20, 40, and 80 bbl/h.  Large capacities are deployed early in the life of the well when large amounts of flowback water are produced from the fracking process.  Later in the life of the well, water production decreases so smaller units will be deployed.

 

  • Easy servicingThe equipment will be highly instrumented and remotely monitored so that servicing needs are readily identified.  In many cases, field servicing is easily accomplished by swapping out non-functioning parts.

  • EnvironmentalThe recovered water is salt free and can be recycled to nearby oil wells without draining local water reserves.  The water can also be used for crop irrigation, or drinking water for animals or humans.

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StarDesal™ Competition:  

  • Reverse osmosisReverse osmosis (RO) membranes foul readily and must be replaced frequently.  Most oilfield brines require significant pretreatment to avoid damaging the membranes.  RO is not able to produce high-concentration salt solutions, so the disposal volume is not reduced significantly.  RO is commonly viewed as the most energy efficient desalination technology; however, StarDesal™ is equally efficient for the same operating conditions. 

 

  • Multi-effect evaporatorsThis technology is robust and can produce high salt concentrations; however, it is not energy efficient.

 

  • Centralized vapor-compression distillationUsing conventional technology, vapor-compression distillation can be practiced at large scale in centralized facilities.  The water must be trucked to the facility, which is expensive and damages roads.

 

StarDesal™ Applications:

  • Oilfield brineAs described previously, StarDesal™ can be used to process oilfield brine at the well site, thus avoiding costs of transporting water via truck.

  • Mineral recoveryMany important minerals (e.g., lithium) are produced by “solution mining,” meaning water is pumped below the earth to dissolve valuable minerals.  Traditionally, the salt-laden water is pumped to the surface and evaporated in large open-air ponds, which is costly and negatively impacts the environment.  StarDesal™ has less negative impact on the environment and produces product immediately whereas open ponds can take years to produce the first product.

 

  • Municipal water desalinationBrackish, salt water and the brine that exits municipal water desalination plants can be concentrated further to form dry salt separated from the remaining distilled water.  This salt can be a source of valuable minerals (e.g., de-icing salt, potassium fertilizer, magnesium metals, lithium, gold).  This technology enables “zero-discharge” desalination, which reduces environmental damage from discharging concentrated brine into the ocean.

 

Markets

 

StarDesal™ can be used anywhere that oilfields have issues disposing of brine or sourcing water for fracking, water floods, or steam floods. 

 

Below is some relevant market information for the United States:

  • In 2012 (the most recent year for which data are available), the United States produced 21.2 billion bbl of oilfield water.  Assuming a disposal cost of $2/bbl, the total market is about $40 billion annually.  (Note: Disposal costs vary widely at each site, so this disposal cost of $2/bbl is for illustrative purposes only.)

 

 

 

 

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