Requires an application commonly referred to as either “Degasification” or "Decarbonation" and it requires the use of a piece of water treatment equipment called either a “degasifier” or a “decarbonator”.
Both of these are similar in nature and are designed for Carbon Dioxide (CO2) removal from the incoming water. A properly designed decarbonator can remove 99.99% of the free carbon dioxide gas that is present in the water stream. One of the primary reasons for utilizing a decarbonator or degasifier for the removal of carbon dioxide gas is the raise the pH of the water without the need to add caustic. resulting in high-purity water.
The other reason is the remove the CO2 prior to treating the water with Ion Exchange which utilizes Anion or Cation resins to reduce the regeneration cycles for the resin beds. High concentrations of CO2 consume the ion charge within the resins and require more frequent regeneration cycles. The difference between anion and cation resins is that one is positively charged (anion) and the other is negatively charged (cation), cation resins, attract positive ions with their negative charge.
The term decarbonation describes the process of the removal of suspended gas or the conversion of carbonic acids into free Carbon Dioxide. Carbonic Acid (H2CO3) is stable at normal ambient anhydrous conditions. However, Carbonic Acid decomposes when not stable and in the presence of any water molecules to form carbon dioxide (CO2). The Carbonic acid breaks down when present in water and it is converted to a gas based upon certain conditions. It is common to have CO2 present in water requiring a decarbonation process when utilizing certain types of water filtration such as membrane filtration with reverse osmosis or it can be present when the need to adjust pH is required. When removing (CO2) the process is often referred to as “Decarbonation”, when removing (H2S) Hydrogen Sulfide the process is often referred to as “Degasification”.
Degasification is the most cost-effective and economical method for the removal of Hydrogen Sulfide (H2S), and Carbon Dioxide (CO2).
Each of these gases can be effectively removed from the water when utilizing a “Degasification or Decarbonation System”. A properly designed decarbonator will remove CO2 levels to as low as 99.99%. A well-engineered and manufactured “Degasification” tower can removeH2S also to 99.99% or BDL. There are certainly other variables that play a role in the removal efficiency of both a decarbonator and degasifier. These variables include items such as the total inlet water flow rate, the inlet feed temperature of the water, the ambient air temperature, and the inlet concentrations that can be expressed as parts per billion (ppb), parts per million (ppm), or Mg/l, and the desired effluent removal levels also expressed in the same method. It is also important to fully understand the actual application and the use of the water to determine how critical maintaining critical levels are and what impact variations will create for the final use. Understanding these variables will aid you in the design of the system and any additional redundant systems needed to assure full compliance with standards.
- # 1 Forced or Induced Draft Decarbonation with vertical towers. (Lowest cost highest efficiency)
- # 2 Vacuum or De-aeration (Vertical tower under a vacuum). (Higher capital/operating cost)
- #3 Membrane degasification or liquid cell (Highest capital cost and operating cost)
The capital cost is calculated with the complete system components and infrastructure required to operate and the operating cost considers the cost of operation from electrical cost, cleaning cost, repair and replacement cost, and time required to operate and maintain. So, when choosing and selecting a method to perform decarbonation first obtain an analysis of your water to allow a full and complete calculation to be performed.
Reverse Osmosis is often followed by “Degasification” to remove the remaining dissolved gases such as Hydrogen Sulfide (H2S) or Carbon Dioxide (CO2).
Membrane filtration only removes solids from the water so any free form of gas or residual solid that is converting into a gas will still be present and can cause damage downstream from its corrosive nature and will raise operating costs. Degasification is utilized to remove the free dissolved (H2S) and (CO2) gas that remains in the permeate water prior to either additional treatment such as ion exchange or pre-chlorination. Removing H2S before the addition of chlorine reduces the amount of chlorine required to achieve the necessary residual levels while also improving the water quality by lowering the TSS. This improves the clarity of the water. The Degasification process is also used to remove (CO2) to raise the pH without the need for additional chemicals such as caustic which reduces the cost of operating the treatment process. DeLoach Industries has been successfully designing and manufacturing Decarbonation and Degasification equipment for over 50 years.
Post-treatment of the airflow from a degasification or decarbonation tower can be required if the (H2S) levels are high enough to create either an odor nuisance or a harmful off-gas environment.
A degasification tower that is being utilized in a steam process prior to a boiler feed system may be located where other workers will be exposed to the off-gases creating a potentially harmful working environment. In addition, if the gases are left untreated they often create a very corrosive environment for all surrounding equipment. The (H2S) combined with water vapor or moisture will create sulfuric acid and cause corrosion on surrounding metal exteriors just as the (H2S) if left in the water will cause corrosion inside a steam boiler system. There are many types of odor control or air emission scrubbers available that attach to the off-gas system of the degasifier or decarbonator. Click the link to learn more about Industrial Water Treatment. For more information or to learn more contact the professionals at DeLoach Industries Inc. at (941) 371-4995.
