A porous sprayer is a device that can be used to introduce gases into liquids in different process applications.
The main function of a porous sprayer is to efficiently introduce gases into liquids.
It has thousands of fine holes that release countless tiny bubbles into the process liquid.
Porous sprayers produce more and smaller bubbles than any other type of sprayer, thus increasing the surface area of gas/liquid contact.
As a result, they significantly reduce the amount of gas and time required to distribute the bubbles in the liquid.
Porous sprayers have a network of pores that create a number of tiny bubbles as you pass pressurized gas through them.
The bubbles are typically between 0.5 and 10 microns and help transfer the gas efficiently into the liquid.
You can use porous sprayers in many industries to perform an unlimited number of operations in a wide range of applications.
These devices can be configured in different shapes and sizes to meet the needs and special requirements of specific industries, processes and applications.
Custom sizes and shapes can be matched with additional hardware as required to meet your specific spraying conditions.
Some of the processes and applications that require the use of a distributor include
Carbonation: to introduce carbon dioxide gas into beverages and beer for preservation
Aeration: for waste streams to meet biological oxygen demand
Bioremediation: Introducing air to promote bacterial proliferation in waste treatment
Agitation: used in various industries to promote efficient mixing of different liquids in tanks/vessels
Fermentation: Injection of oxygen to promote the growth of cells cultured in fermentation conditions
Oxygenation: to introduce oxygen in fish ponds or aquariums
Ozonation: Ozone injection for ultra-purification of water systems in the pharmaceutical industry
Oxygen bleaching: Oxygen spraying to bleach pulp in paper making
Oxygen stripping: for the production of edible wines, juices and edible oils, where nitrogen injection is used instead of oxygen to improve product life
Hydrogenation: Hydrogen injection for a wide range of hydrogen chemical processes
Dehydration: Important in the automotive industry for removing water entrained in motor oil by nitrogen injection.
Oil flotation: Removal of water from oil wells by injection in nitrogen or air.
Gas/Liquid Reaction: Used to improve process performance by injecting oxygen, air and other gases into the reactor.
pH Control: To adjust the pH of process streams or wastes by injecting ammonia or carbon dioxide.
Chlorine bleaching: spraying chlorine to bleach pulp in paper making
Column flotation: flotation of coal and separation of other solids by jet air
Expansion: introduction of nitrogen by injection when expanding mustard or salad dressing
Removal of volatiles: Removal of volatile organic compounds from waste streams by jet air
Steam Injection: Eliminate steam hammer and direct heating by injecting steam
When ordering a porous distributor for your application, you should select the distributor keeping in mind the type of process application on which you intend to use the distributor.
Static distributors are used for tank/batch processes, while dynamic distributors are designed for continuous applications in channels or pipelines.
Porous distributors are available in a variety of designs such as perforated tubes, rings, frames, plates and grids.
Porous distributors contain distributor elements that produce tiny bubbles and a connection base that connects to the gas line.
The use of a high quality and efficient porous sprayer will have the following advantages.
Efficient and gentle transfer of large amounts of gas into the liquid
Increased gas-liquid contact area
Shorter volume and time required for the liquid to dissolve the gas
Lower operating costs due to reduced time and fluid volume
Cleanable and reusable
Increased diffusion rates
Uniform and well-defined gas distribution
Lower energy costs due to reduced gas consumption
You can use different types of construction materials to make porous sprayers.
Choosing the most suitable material will depend on the operating temperature and pressure, flow rate, corrosive effects of the fluid and gas, etc.
Typically, most porous sprayers are made of stainless steel (SS) 316L.
However, you will need porous sprayers made from polypropylene, sintered porous polyethylene, ceramic, glass, SS 304L, SS 347 SS, SS 430, Monel, nickel and other alloys.
Advanced metal alloys such as Hastelloy and Inconel are suitable for making porous sprayers that operate at extremely high temperatures and under highly corrosive conditions.
Compared to other brittle materials that can break under pressure, porous metal sprayers are stronger and more resistant to mechanical shock.
You can also make metal porous sprayers using metal powder media, metal fibers or mesh for optimum economy.
There are different types of porous sprayers, including
Static Porous Sprayers
Static porous sprayers are tank sprayers that are used to introduce gas into a liquid inside a tank or container.
You can use in-can distributors for batch and continuous processes in tanks with agitation or luck agitation.
For applications with small tanks, a single porous sprayer is usually sufficient.
For large tanks, you will need to distribute multiple porous distributors together in a linear or radial pattern.
When your tank is stirred, you should use reinforcement.
Dynamic Porous Distributors
Dynamic porous sprayers are designed to be used inside pipes.
In-line (non-intrusive porous sprayers)
Side-flow porous sprayers
Tangential (invasive porous sprayers)
A good porous sprayer should be designed to support the efficient distribution of gas into the liquid at the most profitable production cost.
A high quality porous sprayer should have the following characteristics to support smooth gas transfer
Materials of construction should be non-corrosive and able to withstand extreme temperatures.
The connector design and distributor diameter should meet the requirements of the application.
The material should be able to withstand strong mechanical shocks
It should be compatible with other hardware that may be required for some specific types of applications
It should be easy to install and replace
It should be easy to clean
The construction should be robust and of high quality all-welded construction
Uniform and fine pore size contributes to the mass distribution of tiny bubbles
Should have a wide range of media pore sizes to control bubble size
Should be available in a variety of standard and custom shapes and sizes
Should have sanitary furniture if required
Designing custom porous sprayers can be challenging if you don't pay attention to the key aspects that directly affect the effectiveness of your equipment.
You can follow these tips to help you make a porous sprayer fit your application needs.
- Know your objectives and application details
You need to thoroughly outline the project output you expect to achieve and the details of your process application.
You should answer the following questions in detail.
What is the nature of your application? Are you carbonating, controlling pH, oxygenating, etc.?
What are the properties of your liquids and gases?
Is it a batch application or a continuous application?
What is the flow rate, pressure and temperature of your system?
At what rate do you want the gas to dissolve in the liquid?
- Calculate the actual volume of gas that needs to be dispersed into the liquid per minute
You need to determine the actual cubic feet per minute (ACFM) that the sprayer must supply into the liquid.
You can calculate this value based on standard CFM and gas temperature and pressure.
- Determine the proper gas exit velocity
Determining the optimum gas velocity is critical to help avoid agglomeration effects.
When gases agglomerate, bubbles become larger and they lose surface area, which increases the number of bubbles needed to achieve the desired distribution.
As a result, you will use more gas and energy to achieve the same level of injection.
The optimal velocity will help you save valuable gas and save energy costs due to reduced or no coalescence effect.
- Determine the required spray surface area
The spray surface area depends on multiple variables specific to the application.
Various aspects of the total surface area will affect the number, shape and size of porous sprayers required for your system.
You can consult with a professional to help you determine the surface area that is best for your application system.
- Determine distributor geometry and inclusions
This is the final step in designing your sprayer and will consider the intricate details to meet the needs of your typical application.
Consider the most appropriate material for constructing the porous distributor, the ideal media grade or pore size, the size of the distributor, and the number of distributor elements required.
You can work with our engineers to help you design the most efficient injection element for a reasonable budget.
The size of a porous injector is calculated based on the gas exit velocity.
You must keep the velocity below the maximum velocity to continuously produce small bubble sizes.
An inline distributor located in the tubing can support higher gas flow rates because the tubing forces can shear the bubbles away from the injector.
The temperature and pressure of the liquid will indirectly affect the size of the distributor as they affect the actual cubic feet per minute.
Compared to other types of sprayers constructed from drill pipes and other similar devices, porous sprayers have many beneficial characteristics.
A porous sprayer allows bubbles to enter the liquid smoothly and efficiently by creating hundreds of thousands of tiny bubbles.
As a result, you can save a lot of money and time because the smooth transfer of gas reduces the volume and time required to dissolve the gas.
In contrast, borehole tube distributors and related devices provide a way to transfer bubbles into the liquid dramatically and inefficiently.
Borehole jets also produce large bubbles that increase the gas/liquid contact area and the time required to dissolve a unit volume of gas.
Since drilled gas distributors produce large bubbles, you will need more gas, which can lead to higher production costs.
The in-line life of a porous sprayer varies significantly depending on the material of construction and frequency of use.
Even in oxidizing environments with temperatures above 1450°F, porous sprayers constructed with all-metal materials of construction can serve you for several years.
The efficiency of a porous sprayer's gas distribution depends on many factors.
Some of the most critical factors that directly affect performance include
Contact time between the liquid and the gas
Pressure of the gas
Temperature and pressure of the liquid
Gas flow rate versus liquid flow rate
Gas outlet velocity
Actual capacity of the air compressor
Porous metal sprayers are more reliable and have a proven performance record than sprayers constructed using other materials.
You should consider using a porous metal sprayer because it offers the following distinct advantages.
Durability: Compared to other materials, porous metal sprayers can maintain a useful life over many years of effective spraying due to their high structural integrity.
Strength: Porous sprayers made from metallic materials have unmatched tensile strength, which makes them beneficial for applications that operate at high flow rates and pressures.
Uniform porosity: Sintered metals facilitate the construction of porous sprayers with uniformly distributed, uniform pore sizes. The availability of different grades of media with different pore sizes allows you to control the size of the resulting bubbles.
Reusability: You can restore the efficiency of your metal porous sprayer to near original condition with proper periodic cleaning. You can clean the media using reverse pulse technology or other suitable methods.
Heat resistance: The robust construction and perfectly welded seams and joints can withstand very high temperatures even under oxidizing atmospheric conditions.
Multiple materials to choose from: In addition to stainless steel, you can choose from many different types of metals to meet project specifications.
Selecting a porous sprayer with the most appropriate performance will help achieve the best spray results at a reasonable production cost.
When selecting a porous sprayer, ensure that it meets the following characteristics.
The material of construction should be able to withstand the corrosive nature of the gas and process fluid.
The average pore size should be capable of producing bubbles of the desired size.
The pores should be evenly distributed to allow for fast and efficient mixing of gases into the process liquid
The material of construction should meet the cleanliness requirements of the sanitary process
The distributor should have a high tensile strength. It should be able to withstand high mechanical shocks and maximum process temperatures.
You should also ensure that the porous distributor can withstand the working pressure of the system
Yes, you can clean metal porous sprayers by different techniques.
The most appropriate method will depend on the frequency of use and the type of liquid and gas being handled.
You can determine the number and size of bubbles produced by a porous sprayer by using video analysis techniques.
There are different classification schemes for the porous media used to construct porous sprayers.
The two most important classification schemes are the ASTM and ISO classification schemes.
Thus, both standards classify porous materials into four different classes, super coarse, coarse, medium and fine.
The categories depend on the pore size of the porous media.
For example, the ISO 4793 standard classifies ultra-coarse materials from 100 to 250 microns, coarse materials from 40 to 100 microns, medium materials from 16 to 40 microns, and fine materials from 10 to 16 microns.
On the other hand, the ASMT classification is more stringent.
The fine group has porous materials with pore sizes ranging from 4 to 5.5 microns, medium from 10 to 16 microns, coarse from 40 to 60 microns, and ultra-coarse from 10 to 220 microns.
Jet steam for in-tank heating has shown some weaknesses in some process applications. These include
Rough handling: Poor mixing and condensation can lead to violent vibration and steam hammer.
Uncondensed steam collapses when it touches the cold tube, which creates space for water to rush in and fill the void.
Under severe conditions, the pressure from the water can cause thumping or steam hammer and vibration.
Energy Loss: Direct energy loss can come from uncondensed steam, resulting in reduced efficiency and increased demand for the amount of steam needed to heat the fluid.
Temperature Control Inefficiencies: When uncondensed steam escapes into the atmosphere or condenses downstream, the steam energy is not recorded in the temperature controller. This situation can lead to fluid overheating or temperature changes.
Hot Zone: Porous sprayers can create a hot zone around them that may burn heat-sensitive materials.
Clogging: The holes in the distributor should be large enough to avoid clogging by concentrated solids at the bottom of the column.
They should also be able to withstand the long runs required by industrial setups.
However, reducing the pore size for smaller bubbles and preventing clogging remains problematic.
As a result, these challenges may limit the efficiency of porous sprayers for small-scale or laboratory testing rather than full-scale operation.
Shutdown: You must also shut down the flotation operation for maintenance and repairs and to allow the slurry to penetrate the air system.