Thermal vapor compression (TVC) excels when high-temperature and high-pressure steam surpasses evaporator requirements. TVC enables low-pressure waste steam from the evaporator to rise to higher pressures. The core distinction between TVC and conventional evaporators lies in TVC's partial utilization of the latent heat of vaporization. As the evaporator doubles as a partial condenser, nearly half the latent heat is recycled, with minimal heat rejection to cooling water.

Vapor from the evaporator's mist eliminator flows to the thermovapor compressor. Motive steam elevates the flashing vapor to a higher pressure, serving as the heating medium for the system. The upgraded vapor condenses in the forced circulation or falling film heat exchanger, driving evaporation. Depending on the quality, condensate can return to the boiler or another water recycle loop. By reusing low-pressure, flashing vapor, the system reduces steam consumption. It's designed for automatic steady-state operation, demanding minimal operator attention, and seamlessly integrates with various Aquatech evaporator body configurations. Using an ejector ensures a low-maintenance design, as steam compression involves no moving parts.

Key benefits of TVC:

• Lower energy consumption
• Reduce steam consumption
• Reduce cooling water consumption

Mechanical vapor compression (MVC) is a highly efficient process that harnesses mechanical energy to drive evaporation and condensation. What sets it apart from conventional evaporators is its full utilization of the latent heat of vaporization. In this innovative system, the evaporator doubles as the condenser, ensuring the complete recycling of latent heat without any heat rejection to cooling water.  This design usually eliminates the need for outside heat sources like steam. An MVC system is also known as an open-cycle heat pump.

The process begins as the evaporated vapor flows through a mist eliminator, eventually reaching the compressor's suction. The compressor increases the saturation pressure through its work on the water vapor, causing condensation at a higher saturated temperature. The compressed vapor flows to the evaporator's heating side, transferring the latent heat of vaporization back to the liquid film on the tube side.

Key benefits of MVC:

• Reduce overall energy consumption for evaporation 
• Idea for situations with limited steam or cooling water availability 
• Meet lower air emissions requirements while maintaining efficiency 

A multiple-effect evaporator is a heat-efficient apparatus that utilizes steam to evaporate water effectively. In a multiple effect evaporator, water is boiled in a sequence of vessels operating at progressively lower pressure levels. As the boiling point of the water decreases with pressure, the vapor produced in one vessel can heat the next vessel. Only the first vessel requires a source of external heat.

Multiple effect steam is used to evaporate water from the first effect. The vapor produced from the first effect is used as a heating medium for the second effect. Vapor from the second effect is used as a heating medium in the third effect. The vapor produced on each effect passes through a mist eliminator. After mist elimination, the vapor on the last effect at the lowest pressure flows to an air-cooled or water-cooled condenser. The vapor is condensed on the outside of the tubes, transferring heat to the circulating brine inside the tubes. Condensed vapor (distillate) is collected in the distillate tank and pumped out of the system through the feed/distillate preheaters. The excess vapor is released into the atmosphere through a vent. Steam condensate condensed in the first effect evaporator is recycled back to the boiler. 

The product from the first effect flows to the second effect evaporator system. The product from the second effect is further concentrated in the third effect. The feed is concentrated to approximately 5% of total solids in the evaporators. The Blowdown from the third effect is collected in the blowdown tank and pumped to the evaporation plant battery limits. 

Vertical falling film evaporators are designed with a very low delta T (temperature difference between the heating medium and the boiling brine) and a high circulation rate.  The two main benefits are a reduced scaling rate and a lower steam requirement. Energy efficiency is maximized by utilizing the outgoing distillate and vent steam to preheat the incoming feed.

Due to the low delta T used in vertical tube falling film (VTFF) evaporator units, they are well suited for heat-sensitive products that require gentle processing (i.e., Food & Beverage Product Concentration). 

VTFF evaporators use vertical tube bundles with brine evaporating from a thin film inside the tubes. A proprietary distribution system using spray nozzles ensures that each tube has a sufficient liquid film on the inside. This design eliminates plugging associated with conventional insert distributors. Tubes can be inspected through the manway with no disassembly required. Brine is distributed in a thin film down the inside of the tubes. The brine absorbs heat from condensing water vapor on the outside of the tubes. The latent heat of vaporization transfers from the water vapor through the tube wall to the thin brine film inside the tube. 

The brine is introduced at the top of the vessel and flows downward as a falling film. The brine is uniformly and generously directed to the full circumference of each tube as a thin film. Because the recirculation rate is many times greater than the evaporation rate, only a small change in concentration occurs down the tube length as evaporation takes place. The recirculation rate is chosen conservatively to ensure the heat transfer surface is well-wetted and localized drying is not encountered. 

The vapor condensing on the tube bundle is primarily water vapor but can also contain air and other non-condensable. These non-condensable will stay near the tube walls and impede heat transfer unless swept away by sufficiently high vapor velocities. A vent on the evaporator body continuously removes the non-condensable to maintain high heat transfer coefficients and to prevent loss of driving force (differential temperature) through excess sub-cooling of the heating vapor. 

Falling film evaporators use vertical tube bundles with brine evaporating from a thin film inside the tubes. Brine is distributed in a thin film down the inside of the tubes. The brine absorbs heat from condensing water vapor on the outside of the tubes. The latent heat of vaporization transfers from the water vapor through the tube wall to the thin brine film inside the tube.

Falling Film Evaporators are a very energy-efficient evaporator design that can operate with a very low-temperature difference between the brine and motive steam due to the high heat transfer coefficient of the thin brine film.

The SprayFilm® technology revolutionizes how liquor for evaporation interacts with the heating tube bundle. This SprayFilm evaporator design provides easy access to both the tube and shell sides, facilitating the removal of deposits using chemical or mechanical cleaning methods.

As the feed enters the SprayFilm evaporator, it undergoes preheating, benefiting from the heat transferred by the outgoing distillate water stream. The feed mixes with the resident concentrate within the evaporator body. The concentrate circulates over the heat transfer surface, where a portion of the water vaporizes, while the remaining liquid becomes more concentrated as it descends along the exterior of the heat transfer tubes.

During this evaporation process, vapor is generated and passes through chevron mist eliminators, effectively removing entrained water droplets. This vapor then proceeds to the inlet of the vapor compressor, where it undergoes pressurization, increasing vapor pressure and saturation temperature. The vapor enters the tube side of the SprayFilm evaporator, transferring its latent heat of vaporization through the tubes as it condenses. Finally, the distillate flows into a hotwell and is pumped through the feed/distillate preheater.

MoVap offers a convenient, mobile solution for on-site flow back water treatment at the well pad, producing ultra-clean water with total dissolved solids (TDS) below 500 ppm. This not only allows for efficient recycling and reuse without the expense of transporting water to off-site treatment facilities but also significantly reduces wastewater volumes, leading to cost savings on disposal.

 Our options include MoPress, a mobile filter press, a generator to power MoVap, and frac tanks for flexible water storage solutions. 

Key benefits of mobile evaporation:

• Ultra-clean water with TDS <500 ppm
• Reduce wastewater volumes
• Comply with PA DEP regulations for treated water
• Mitigate down-hole scaling concerns

Aquatech’s HEVAP™ High-Efficiency Evaporation technology is used to process wastewater and achieve zero-liquid discharge (ZLD) at a high availability. Conventional crystallizer designs struggle with high concentrations of silica and organics, and those systems can be plagued with premature cleaning cycles and lower availabilities. To overcome these challenges, Aquatech’s HEVAP technology specifically conditions the feedwater to the ZLD system so that the evaporation process can operate at high availability.  

HEVAP^TM Technology includes the following primary process steps. The feed water to the system is a mixture of RO reject, backwash waste, cooling tower blowdown, DRI blowdown, and treated wastewater.

• Hardness Removal - A softening water clarifier system treats the blended wastewater streams, reducing the hardness content to less than 10 mg/L as CaCO3. Calcium and Magnesium ions (along with smaller concentrations of iron and aluminum) are conventionally the bad actors in produced water evaporation systems, which initiate alkaline and silicate scale formation due to their multi-valent charge structure. Removing these species upstream of the evaporation systems mitigates scale formation on the heat transfer surfaces.  
• Alkalinity Removal - Produced water contains carbon alkalinity (i.e., bicarbonate and carbonate), which tends to come with residual hardness to form scale.  Acid injection converts the alkalinity to carbonic acid/carbon dioxide, degassed in the deaerator by a counter-current steam stripping action.  
• Silica Solubilization - Silica is solubilized and rendered non-scaling by increasing the pH with Sodium Hydroxide (Caustic) dosed downstream of the deaerator (after alkalinity removal).  
• Evaporation - The conditioned feed, now free from scaling compounds, can concentrate in the evaporation system at a very high recovery without scaling.