Open-to-atmosphere evaporator, operating at low temperatures to concentrate brine.
Introducing the AirBreather: Lower Cost Evaporator Crystallizer
Oct 15th 2018
- A lower cost evaporator crystallizer has emerged—the SaltMaker AirBreather. It is based on the robust backbone of its closest relative—the SaltMaker MultiEffect.
- It offers four times the capacity, at four times higher thermal energy load vs the MultiEffect; it is best suited where thermal energy costs are < $5/GJ (or $5/MMBTU).
- The AirBreather optionally reduces volume with either clean water return, or volume reduction without a liquid water by-product.
- Wastewaters never contact atmosphere, so volatile organic compounds (VOCs) are not released, unlike conventional open-to- atmosphere evaporators that boil water directly to atmosphere, placing air emissions at risk and raising site concerns.
- The AirBreather decreases trucks on roads and reduces produced water volumes for offsite disposal.
- It can concentrate to any point: concentrate heavy brine or make solids and achieve true zero liquid discharge.
- It cleans itself while it operates, and is built from non-corroding, non-scaling, modular components, well suited for remote dispatch.
The Origins of the AirBreather
Saltworks originally developed the SaltMaker MultiEffect—the AirBreathers’ older ‘cousin’—in partnership with Canadian oil sands companies. They were seeking to use waste heat thermal energy to treat challenging heavy oil blowdown water. The industrial end users set out the following criteria:
- Build the most reliable and cost effective evaporative-crystallizer, re-engineering from the ground-up to be suited for oil and gas.
- Remove boiling on heat transfer surfaces, which is the origin of most scale.
- Develop a new solids management system, removing the challenges of centrifuges and driers, while producing automated bagged solids suitable for landfill disposal
- Deliver a modular, expandable plant, that can be serviced without confined spaces.
- Remove single point of failures, such as the vapor compressor in MVR systems.
- Employ 60–80 °C waste heat, which is abundant in oil sands.
Saltworks answered this challenge with the SaltMaker MultiEffect. It replaced steam and scaling heat transfer surfaces with an air humidification-dehumidification cycle, which evaporates and condenses water in successive effects. Clean water is produced by each effect, with the final effect open to atmosphere to cool the plant. The machine is designed to remain scale-free.
After having completed shale field pilots of the SaltMaker MultiEffect, the team realized that a better configuration existed for shale: leveraging waste thermal energy with an open to atmosphere evaporator that can manage volatile risk. Capacity improved four times per unit of equipment. However, thermal energy also increased four times. As engine jacket cooling water or low-cost gas may be available, this is less of a barrier in shale.
What Do I Need to Know About Open Evaporators?
Open evaporators release water vapor to atmosphere, so there is no condensed water to manage. However, evaporating water requires a lot of energy: 2400 MJ per tonne. In addition, produced water includes more than just water. It includes salt that can scale and corrode the plant, and toxic volatiles such as benzene or ammonia that can pollute the atmosphere or cause health problems. The AirBreather overcomes both challenges through innovation.
Up until recently, most open evaporators were of the submerged combustion type. Combustible gas and compressed air are injected into a large “kettle boiler.” Combustion occurs underwater and heat is transferred directly to the salty water. Water is concentrated, and vapor is released, often resulting in a tall plume rising through the sky. These large kettles must be metallic to withstand combustion temperatures, while also made of exotic materials to reduce corrosion risk related to high salinity. Emissions must also be managed since combustion is involved. Other open types may heat the water making use of direct contact with exhaust gas, or heating via a heat exchanger. Regardless, volatile emissions can still emerge.
The AirBreather overcomes this avoiding any contact of the wastewater with air. The evaporation chambers are 100% sealed from the atmosphere. We provide customers with two options: return freshwater fit for surface discharge, or reduce volume by sending only clean water to atmosphere. How we do this is a proprietary secret that we will release to customers under NDA.
When developing the AirBreather, we aimed to pack extremely high evaporation capacity into a small repeatable module. Every AirBreather AB-100 consists of 4 evaporation modules, packaged into ISO container frames. The entire plant is built around ISO container frame modules, for ease of delivery, installation, and expansion to suit project needs. The “100” in AB-100 stands for 100 tonnes/day of produced water volume reduction (600 barrels per day or 26K GPD). Larger plants can be built by simply adding AB-100s, allowing customers to grow their volume reduction capacity over time.
Evaporating water is easy; however, managing volatiles and achieving extremely high brine concentration or solids production to realize zero liquid discharge presents new challenges.
Wastewaters can contain substances with low boiling points that will evaporate with water. Examples include ammonia, or volatile organic compounds (VOCs) such as methanol, BTEX, and others. Odor may also impact neighbours. The AirBreather’s proprietary “Volatile Management System” prevents volatiles from atmosphere contact so that only safe, clean, low-temperature water vapor is released. Our pilot plants are outfitted with this same system, so we can prove the operations at your site, or ours on shipped water.
Zero Liquid Discharge (ZLD)
As saltwater is concentrated, scale can precipitate, solid salt plugs can form, and high chloride levels will corrode metallic parts. The SaltMaker AirBreather borrows SaltMaker MultiEffect technology to overcome these challenges, resulting in the first open-to-atmosphere evaporator that squeezes every last drop of liquid waste down to a solid by-product or achieves any desired brine concentration along the way. This is accomplished by:
- Corrosion, Plugging, and Scaling Resistance: High circulation rates, constantly changing saturation gradients, and non-corroding, non-stick wetted surfaces eliminate reliability challenges that plague conventional crystallizers.
- Reliable Solids Production or Slurry Brine: A circulating slurry continuously forms and grows crystals. Solid salt is discharged to an automated bagging or binning system. Alternatively, one may choose to extract the slurry brine at any pre-determined concentration.
- Intelligent Automation and Self-Cleaning: The plant has automated start, stop, and hibernate for immediate ramping from 0 to 25% capacity in one step. It operates at any capacity between 25% to 100% in dynamic capacity control mode and will detect and initiate cleaning cycles.
- One Step Treatment: No pre-treatment is required. For ZLD applications, solids are produced without the need for extra process equipment, such as centrifuges or filter presses.
Samples of solids as produced and discharged to an automated bagging system
Saltworks Technologies is a leader in the development and delivery of solutions for industrial wastewater treatment and lithium refining. By working with customers to understand their unique challenges and focusing on continuous innovation, Saltworks’ solutions provide best-in-class performance and reliability. From its headquarters in Richmond, BC, Canada, Saltworks’ team designs, builds, and operates full-scale plants, and offers comprehensive onsite and offsite testing services with its fleet of mobile pilots.
There are four fundamental types of industrial evaporators and crystallizers used for wastewater treatment, brine management, or improving water reuse. Lower your risks and improve costs by understanding the trade-offs between the different evaporator types.
Scale is a crust that forms on membranes, heat transfer surfaces, and on the inside of pipes as salts precipitate out of solution. It blocks flow, disrupts heat transfer, and increases energy requirements for water treatment systems
The many options for managing brine, a term for saline wastewater from industrial processes, fall under two categories: brine treatment and brine disposal. Brine treatment involves desalinating the brine for reuse and producing a concentrated brine (lower liquid waste volume), or residual solids (zero liquid discharge).