Successful Installation of Ozone Generators

Interview conducted by Alessandro PiroliniMar 30 2015

 

How would you define a successful installation of an ozone generator, and what are the main considerations you must make when optimizing an installation?

When choosing an ozone generator, it is important to look at the cost for the complete system, not only the ozone generators. If you choose a generator that produces ozone at a lower concentration, the cost for oxygen equipment and production will be unnecessary high.

I therefore recommend installing and running the ozone generators at concentrations at or above 13% wt. The higher concentration and following lower gas flow will, in many ways, benefit you in the design of the rest of the system.

We always recommend to filter the oxygen in two steps and have the pressure regulator just before the ozone generator. This way the input gas pressure does not depend on the filter status. Before attaching the oxygen connection to the generator is should always be purged. No exceptions!

To minimize the risk of water being pushed backwards in the ozone pipe, causing potential damage, we recommend all installations to be equipped with a backflow protection system. The standard check valve is just not enough. It has to be an active solution that closes automatically, is opened only when told to by the generator or control system and sends feedback to the generator or control system with system status. Otherwise, if it closes and the generators doesn’t stop, the risk for damage to power supplies and reactors are imminent.

If your system has need for redundancy, a system controller that allows multiple units to work as one will minimize the need for redundant capacity. By adding a “back up unit”, but instead of having it in standby, running all units at all times but at reduced duty level, the need for redundant capacity is kept to a minimum.

At the same time, the time for recovery after a failure is minimal. When running an ozone system of multiple units, the need for redundancy can be as low as 20%. That is 5 units for the demand and 1 units for backup capacity, all units running at the same time, but at a reduced duty level of 83% (5/6). A design like this reduces CAPEX by 40%.

With the previously mentioned higher ozone concentration of at least 13% wt, the gas volume is only 50% of the standard ozone generators running at 6-7% wt, and only 25% of the air fed units.

What is the primary function of the Primozone® LOX-booster and how does it work?

When using LOX instead of on-site generated oxygen, it is important to have an optimal amount of nitrogen mixed in to the LOX, which is often neglected. An incorrect amount of nitrogen can lead to reduced capacity and production of nitrogen byproducts that can transform into dangerous products like nitric acid when they come into contact with water.

Using a Primozone® LOX-booster, or equivalent, that seamlessly adjusts the nitrogen level according to the gas flow will improve the ozone production and decrease the need for maintenance.

How do you ensure that an ozone generator doesn’t overheat during operation?

When cooling an ozone generator system, the preferred solution is using a closed loop. Wether the water in the loop is cooled electrically with a chiller or a heat exchanger is not really important, but more dependent on the situation.

Using a closed loop reduces the risk for bio fouling and lime scale in the ozone generator, which over time will build up and decrease the cooling effect. Using cooling water for the complete system, including the power supplies, will decrease the demand for air conditioning the ozone generator room.

The air conditioning system can actually be minimized by introducing an airdryer system like the Primozone® GD. The GD dries the ambient air before it is introduced inside the generator casing.

What are the challenges with distributing ozone to more than one injection point?

Instead of using multiple units when having more than one injection point, a single ozone generator (system) together with an ozone distribution system is a great solution. These used to be a pain to adjust until the Primozone® ODM came along.

The ODM is controlled by a system controller, and you set the demand for each injection point at the system controller. It not only adjusts the flow at each injection point, but also adjusts the ozone production accordingly i.e. it is a 5 second adjustment at the system controller instead of a day’s work to adjust the system.

In what ways can you optimize the dissolution of ozone in water?

As the dissolution system is dependent on the gas volume, it is important to keep the gas volume as low as possible. This way, the cost for booster pumps and injectors is decreased to a minimum.

But the biggest savings is not in CAPEX but in OPEX, as bigger pumps need more power and over time this is a huge cost. Also, of course, the cost for oxygen is reduced by the same ratio as the gas volume.

As for a mass transfer system, I prefer using a static mixer like Statiflo GDS, as it not only is a more energy efficient solution, but also gives a better dissolution than a venturi injector based solution. Dome diffusers are cheap but tend to waste the hard earned money that you have invested into producing ozone, as the mass transfer is very poor.

For more information on mass transfer and the importance and benefits in high concentration and pressure, please read Arash Golshenas article here.

What is the Primozone® BFP backflow protector and how does it prevent ozone generators from being filled with water?

Prior to the mass transfer system, a back flow protector should always be installed. It is important that BFP not only closes when affected by water, but is controlled by the ozone generator or system controller.

A good backflow protector should be completely integrated in the system: open when ozone production starts, closed when it stops or water is coming and providing feedback to the ozone generator or system controller. This is how the Primozone® BFP backflow protector works.

What about residual ozone. How would you recommend destructing that?

When taking care of the non-dissolved and reacted ozone, the higher concentration comes in again, because of the smaller volumes that have to be treated.

With the smaller gas volumes, the energy required for heating the off gas is reduced, the amount of catalysts is reduced, and money is saved. When operating an ozone destructor, it is important to know that the unit is working at its best.

With the Primozone® DXF ozone destructor, this is easy. This unit has, for example, high and low temperature alarms, which I think are a must! You don’t want unheated moist air passing through the catalyst, neither do you want the unit to overheat.

When the unit has a built in fan, the Primozone unit has the possibility of entering a set point value and also having a reading fed back to the control system. If the system is properly integrated, the system controller will automatically adjust the set point for the ozone destructor fan and heater elements according to the production of ozone.

How do you see the ozone generation market progressing over the next decade?

The market for municipal and industrial ozone systems will continue to grow but the grounds for the decision making will change. The end customer will demand more energy efficient solutions and the only way to get there is to use a higher concentration of ozone. Higher ozone concentration reduces the cost for LOX or oxygen generation as well as the energy cost for the dissolution system and ozone destruction units.

How will Primozone® be a part of this change?

Primozone is already setting the standard by redefining ozone technology™ and changing the way ozone solutions are designed.

We strive to always provide the most energy and cost efficient solutions, and are setting a benchmark in the market. We will continue to offer this and meet the customers demand.

About Jesper Kedström

Jesper Kedström is a Sales manager focusing on the industrial projects, but is also involved in municipal projects.

He is managing Primozone's partner program, assisting Primozone's partners in their work, keeping them up to date with technical information and running technical training for engineering companies.

Jesper has a Bachelor of Science degree in computer engineering at Linnaeus University and has, from previous employments, experience from waste water treatment, both industrial and municipal.