In this blog post, we’re going to discuss ozone mass transfer. This is an important topic for anyone working in the water treatment industry, as it affects the efficiency and performance of ozone-based water treatment systems. We’ll provide an overview of what ozone mass transfer is and how it works, as well as some tips for optimizing your system’s performance. We hope you find this information helpful!
The movement of an ozone gas phase into water is known as osmosis. In most cases, O3 needs to be dissolved in water for use.
Ozone gas is slightly soluble in the liquid. High mass transfer efficiencies, however, may be achieved using appropriate techniques and equipment. Ozone can be transferred through either a bubbling or a mixing process with a venturi mass transfer system.
Ozone mass has traditionally been dispersed in water using diffusion stones. Venturi-based mass transfer systems are now the preferred way to dissolve ozone in water due to their simplicity, economy, and effectiveness. A venturi injector has an efficiency of around 90% and can achieve a dissolvability of up to 99% when dissolved into water.
Venturi Injection
A venturi works by accelerating liquid through a narrowing restriction in a pipe or tube, thereby generating a negative pressure or vacuum. A little difference in pressure between the intake and exhaust sides is enough to create a vacuum at the suction port.
Internal mixing vanes generate hundreds of thousands of micro-bubbles in Venturi injectors, greatly increasing the amount of surface area for ozone gas to touch.
In an integrated ozone system, the injector pump pulls process water through the venturi, creating a vacuum that draws in the ozonated air produced by the ozone generator.
Design Considerations
Ozone resistance is an important consideration when purchasing venturi injectors. Because some venturi injectors aren’t made of materials that are resistant to ozone, look for one that is.
An injection system must take into account the gas-to-liquid proportion and pressure. The gas-to-liquid proportion is measured in volume units.
The solubility of a solution is defined as the amount of dissolved gas per unit volume. The higher the proportion of liquid to gas, the more soluble the solution will be. We suggest a ratio of 1:2 for this experiment. The pressure of water has a significant effect on how much ozone gas dissolves in liquid. Higher pressures increase the solubility rate of ozone gas in liquid significantly.
Other important considerations:
- Venturi injectors’ outlets should be above their inlets (water flowing upward).
- Never restrict the venturi outlet.
- Install pressure gauges directly at the venturi inlet and outlet to verify water pressures
Optimizing Ozone Mass Transfer
To meet the demands of each ozone application, the components and operating conditions of venturi-based mass transfer systems must be optimized. A well-designed and optimized venturi-based mass transfer system may achieve a flow rate of up to 98% ozone gas into the solution.
If the differential pressure does not support the gas volume to the venturi, mass transfer efficiency is reduced, and water receives a smaller dose of gas. Gas-to-liquid ratio and pressure at the mixing zone at the discharge end of the injector into the mass transfer vessel have an impact on mass transfer.
If the venturi suction exceeds the output of the ozone generator, exceeding the venturi’s discharge pressure, operation of an ozonator at a particularly high vacuum may damage the cell and oxygen concentrator.
To ensure a safe system, the performance characteristics of the ozone destruct system (maximum flow rate and catalyst capacity) must be compatible with the amount of ozone off-gas that may be produced by the mass transfer vessel.
A truly effective mass transfer system requires careful planning in order to balance the functions of the components and fulfill the application’s overall needs.
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