ED 2000 & WATER TREATMENT PROGRAM

 

The water treatment program is a key facet in maintaining the cooling system at 100% efficiency. There is no replacement for the service, knowledge or expertise required to maintain the water treatment program, but only new tools to assist in making the process easier. The ED 2000 is one of those tools.

There are several goals of water treatment --- scale control, corrosion control, control of biological fouling and the economics of water use. Changes in water quality, field operators or other unforeseen events require constant monitoring of the water treatment program to insure that the balance of treatment chemicals are maintained to match the quality of the make-up water at an identified cycle of concentration. There is a very small margin of error.

The ED 2000 assists in one facet of this program….scale control. The ED 2000 Anti-Fouling System allows for an increased margin of error in maintaining quality condenser water, thus mitigating the risk of failure. If there is a fluctuation in water quality, the bleed is not properly maintained for a short period or there is a shortage of personnel to perform the monthly maintenance checks, the chances of failure with ED 2000 installed are greatly reduced.

The ED 2000 assists in one facet of this program….scale control.

The ED 2000 System is designed to enhance a chemical-based cooling water treatment program. When designing and implementing a cooling treatment program, the following items must be considered:

Scale Control:  ED 2000 is used much like a cooling water inhibitor program in that it causes crystal distortion of the calcium and magnesium ions in the cooling water making them non-adherent to heat transfer surfaces. A chemical treatment program using phosphonates, such as ATMP and HEDP, is very similar. The difference is the ED 2000 causes nucleation of the distorted crystals and uses filtration to remove them.  The chemical program uses a dispersant to retard crystal growth and disperse it throughout the system for removal through the tower bleed. 

A chemical chelating program keeps the hardness causing mineral ions in the bulk solution and is designed to perform in an opposite manner to the ED 2000.  Any polymer used in this form may retard the ability of ED 2000 to provide the desired treatment results.  

Filtration, a very important component to assisting in this process will be discussed further in the fouling control section. 

If the current filtration is less than 5% of the recirculation rate or greater than 15 microns, the cycles of concentration must be decreased to compensate for the reduced filtration rate. In this case, the cycles of concentration should be reduced or the filtration rate increased.

Corrosion Control:  Monomolecular calcium carbonate is an effective corrosion inhibitor. This is a prevalent corrosion inhibitor in alkaline chemistry programs and the key to mitigating corrosion using ED 2000. The cooling water treatment program treated with ED 2000 can be run on the alkaline side and corrosion will be controlled. An oxidizing biocide will stimulate corrosion to both ferrous and copper-based alloys, therefore a non-oxidizing biocide program should be considered. It is recommended that corrosion coupons should be utilized to track the corrosion trends and allow for monitoring and adjustments to the program.

Microbio Control: Control of microbiological growth (i.e. algae, fungi and bacteria) is an important consideration in maintaining a cooling system’s performance. Biofilm contributes to both fouling and scale formation on the condenser tubes since it acts as glue for foulants and an insulator to heat transfer. This process can occur quickly if bio-growth goes unmonitored and uncontrolled. Testing for algae and bacteria should be made on a regular basis using simple on-site BART test and Paddle test kits. The decision to use an oxidizing biocide versus a non-oxidizing biocide will dictate further steps. Corrosion potential increases with the use of an oxidizing biocide. Triazole for copper corrosion has been used as a supplement when oxidizing biocides have been used and should be continued if oxidizing biocide use will continue. As recommended previously, corrosion coupons should also be used to monitor program performance.

 

Fouling Control: The cooling tower can be thought of as a large air scrubber and as such is a collection point for both airborne and waterborne contaminants If not mechanically filtered, these containments will collect in the condenser water basin, heat exchangers and other low flow areas as fouling.  It has been proven that side stream filtration is a very useful tool in mitigating the accumulation of these suspended solids in the condenser water. Typically, a minimum of a 5% filtration rate is recommended. Additionally, side stream filtration will remove the distorted hardness crystals formed through the ED 2000 treatment. Effective system filtration enhances overall system performance relative to the control of scale, corrosion, and fouling, from all sources (i.e. microbio, airborne and waterborne).

 

System Control: Any cooling water treatment program is only as good as its overall system control relative to cooling tower chemistry and conductivity control. This is the most important base-line control factor. An automatic 24/7-type controller can be utilized, maintained and calibrated on a periodic basis. Should this basic control function be inoperable or subject to variation, so will the control of scale, corrosion, and fouling.