Cooling tower Filtration

Common issues with Heating and Cooling Systems

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The Problem

Heating and Cooling Systems whether they are conventional or alternative systems involve water.  Over a period of time this water picks up particulate contamination.  Controlled tests have shown that the combination of scale and biofilm build up can occur in months rather than years on a newly installed system.  This build-up on particulate causes a number of problems within the system resulting in expensive maintenance, repair or even replacement of essential components as well as reduced system performance leading to an increase in energy consumption.

The more common issues experienced by particulate build-up are:-

  • Shortened productive life to chillers and boilers, leading to increased system down-time while expensive repairs, maintenance or even replacement is carried out.
  • Increased wear on pumps and valves leading to premature failure of components and system downtime.
  • Build-up inside boilers leading to system downtime requiring expensive maintenance, repair or replacement.
  • A build-up of solids no thicker than a human hair on pipework can reduce heat transfer and cooling efficiency by up to 30%.
  • Reduction in system efficiency leads to an increase in energy consumption.

 

The Solution

The most effective method of avoiding these issues and reduce risk is to remove the contaminants from the system before the opportunity to “build-up” and latch on to pipework or component surfaces.

This is done through filtration of the process water with-in the system.  When filtering this water down to below 1 micron the following benefits can be experienced.

  • Increased heating/cooling in areas of the system previously suffering from poor performance at system extremities.
  • Reduced system maintenance requirement and increased reliability on system components such as valves and pumps.
  • Increased/maintained system performance due to a reduced level of solids of solids present in the water.
  • A higher level of protection provided to boilers and chillers leading to high reliability and reduced downtime.
  • Higher control over biological contaminants leading to increased effectiveness of chemical dosing operations.
  • Higher/maintained system performance leads to reduction in power consumption providing energy savings.

Through experience filtration to grades of approximately 1 micron is required to effectively deal with the whole scope of issues mentioned earlier (including bacterial contaminants.)

 

Filtration Technologies

There is a wide range of filtration technologies available on the market suited to a whole host of various applications.  Through experience Hydro-Gen have found that the correct solution for this application is a high efficiency filtration connected in side-stream configuration to the system filtering down to less than one micron.

Connecting a filtration in side-stream holds several benefits over in-line filtration methods including:-

  • Smaller unit requirement.  Smaller footprint.
  • Increased return on investment
  • Smaller unit cost
  • Unit functions independently to Heating/Cooling Systems –no interference.

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Technologies on the market

Screen filter technology – Screen filters are an effective method of removing larger particulate (generally down to 20-30 micron) of in-line systems, however as a large percentage of particulate is smaller than this, this would solve only part of the problem.

Hydro-cyclone technology- Due to the nature of this technology this can be effective when the SG (specific gravity) of the particulate is 1.7 or greater, through experience a large amount of particulate in these systems are below SG 1.0, so this would be ineffective.

Bag and Cartridge Filtration:-  Although bags and cartridge are available in a wide range of filtration degrees as these systems are not self-cleaning and as such can create a large amount of consumable waste (usually going to landfill) and require a relatively high degree of hands on maintenance and supervision to maintain their performance.

 

The Correct Technology.

The filtration technology that meets all of these requirements is the Velocitek OVF system supplied by Hydro-Gen Ltd 

The Velocitek system is a high efficiency self-cleaning media filter.   Thanks to patented technology this filtration system can achieve filtration down to 0.45 micron.  The Velocitek can achieve high efficiency removal rate of over 86% at 1.0 micron in one single pass, where conventional filters have to undertake multiple passes to achieve anywhere near this efficiency which is less than ideal when used as side-stream filtration.

The Velocitek is a fully automated system with self-initiated cleaning process when required with minimal maintenance.  As this is a high efficiency filtration system, this technology is suited to side-stream connection providing an increased level of filtration at a small unit size.

 

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