What are chemical inhibitors?
In order to maintain the cooling capabilities of the system and thereby maximizing the value of the cooling system as well as improving the environmental profile, it is vital to perform proper water treatment and preventive maintenance.
By adding chemical inhibitors to the cooling water, it is possible to avoid or minimize the four main issues in cooling systems, namely corrosion, scale, fouling and bacteria growth.
How do chemical corrosion inhibitors work?
Chemical inhibitors reduce corrosion by interfering with the corrosion mechanism, and can affect the reactions at either the anode or the cathode. General corrosion inhibitors protect both anodic and cathodic surfaces by coating all metal surfaces in contact with water with a film.
Which chemical corrosion inhibitors are commonly used?
- Phosphino Succinic Oligomer (PSO)
- Soluble oils
- Triazoles for copper
How do chemical scale inhibitors work?
Since most minerals are more soluble at a lower pH, adding acid to the cooling system can keep the common scale forming minerals dissolved and prevent the start of the crystallization process. This is also called threshold inhibition.
Kinetic inhibitors modify the crystal structure of the scale greatly reducing the growth speed of deposits.
Which chemical scale inhibitors are commonly used?
Organic phosphates, polyphosphates and polymeric compounds can all act as both threshold and kinetic inhibitors.
How do chemical fouling inhibitors work?
The purpose of the chemical fouling inhibitors is to keep the foulants suspended in the water flow thereby preventing them from settling on the metal surfaces. This can be accomplished in two ways. Firstly by a chemical process known as charge reinforcement, where the electrical charge of the foulants are increased thereby causing them to repel one another. Secondly wetting agents can be used to reduce the surface tension of the water, in a sense making the water wetter.
Keeping the suspended materials in the water flow mean that they can more easily be removed from the system either through blowdown or filtration.
Which chemical fouling inhibitors are commonly used?
Charge reinforcers: Anionic polymers
Wetting agents: Surfactants
How do chemical bacteria inhibitors work?
Generally three types or classes of chemicals are used to control bacteria and microbes:
- Oxidizing biocides
- Non-oxidizing biocides
Each type of chemical has a distinctly unique method of dealing with microbial control.
These biocides can be applied continuously or on a slug basis, and function by oxidizing the cellular components in microorganisms thus resulting in death of the organisms. Gaseous chlorine and liquid sodium hypochlorite are the most widely used products.
Non-oxidising biocides describe special chemical agents that function by mechanisms other than oxidation, including interference with cell metabolism and structure.
Unlike the two previous biocides, biodispersants do not kill microorganisms. By loosening microbial deposits they are kept in the circulating cooling water flow and are eventually flushed away by blowdown. They can also be applied in combination with oxidizing biocides by exposing new layers of microbial slime to attack from the oxidizing agents.
In Guldager’s laboratory facility we can perform these tests and our service technicians can perform the onsite sampling and reporting.
To cope with these issues Guldager offers a service/maintenance contract tailored to individual needs.
Guldager’s catolysis system provide inhibiting effect. Catolysis is a further development of electrolysis. By means of two electrodes in a leading medium and impressed current, aluminium can be dissolved in water and thereby a very effective inhibitor has been formed. More than 40.000 of these solutions have been sold throughout the world and protect all types of installations from cooling systems to heating systems against corrosion. The plant has been in Guldager’s programme for the last 60 years and the gained practical know-how is extensive.