How to Clean and Maintain Your Industrial Cooling Tower
A cooling tower is an essential part of an industry’s heat rejection process; going without it could cause a detrimental setback in temperature control. Therefore, keeping it in top shape is crucial and will require you to have a cooling tower maintenance plan complete with anti-clogging measures for effective operation. Here is a step-by-step guide that will be worth your while to learn how to clean and maintain your industrial cooling tower.
How to Clean a Cooling Tower
The first phase of cleaning starts with:
Chlorination
Chlorination refers to a chemical disinfection process that helps prevent bacterial growth, such as the lethal Legionella. According to the Centers for Disease Control, the necessary free residual chlorine level should be 50mg/L. Achieving this will require you to utilize industrial supplies, with the option of diluting 0.6 pounds of calcium hypochlorite per 1,000 gallons of water being an ideal start. Another alternative would be using 10.5 pounds of NaOCl with 3%-5% chlorine per 1,000 gallons of water.
Whichever option you settle for, add 10-25 pounds of automatic dishwashing detergent to 1,000 gallons of water. This should be done within 15 minutes of adding your disinfectant. Allow the water to settle for a day, after which you can drain the system. Follow this up by refilling and disinfecting one more time.
Clean the Cooling Tower’s Hot Deck
An effective cleaning process requires a hose with a low-pressure water spray that allows you to get to all the cooling towers’ nooks. Target the nozzles, hot deck, and orifices to ensure you eliminate scale deposits that may be forming. While doing this, check for any missing nozzles or damage to them, ensuring you replace them for effectiveness during the heat exchange.
The next part will be cleaning the basin and tower surfaces of your cooling tower. These are some of the most affected areas prone to bacteria formation during the cooling process and when the heated water is ejected from the tower. After you are done cleaning, disinfecting any contact surfaces that are likely to be in the water’s pathway during cooling and evaporation.
Clean All Distribution Pans
Next, clean off any sediments, scale, and biofilm that may have begun accumulating on the distribution pans. Along with this, look for any damaged or missing components that need fixing or replacement.
Vacuum the Tower Sump
When complete draining of the cooling tower is impossible, the tower sump can act as storage for remaining debris. For a thorough cleaning process, ensure that the sump is well vacuumed, paying attention to debris and sludge that may be left behind.
Disinfect the Fan Housing and Tower Basin
When left untreated, the tower basin and fan can also harbor bacteria that contaminate the cooling tower’s air and water. Inhaling aerosols from these water sources comes with health risks, with fatalities being a common occurrence. Disinfecting the tower basin and fan will go a long way in preventing the spread of any harmful bacteria while working to kill any poisonous microorganisms.
Properly Dispose of the Debris
After cleaning out the cooling tower, properly dispose of the debris to ensure the sediments and bacteria do not pose a health hazard due to spills and runoffs. Generally, a sanitary sewer is enough for disposing of your debris. But even with this, practice diligence and check with your municipality concerning waste removal of solid debris.
How to Develop a Cooling Tower Maintenance Plan
With cleaning not being an everyday task for cooling tower personnel, developing a cooling tower maintenance plan will still allow you to get effective performance in your facility. Here are some practices that will come in handy for your maintenance plan.
Schedule Monthly Treatments
Chemical water treatment should be an essential part of your cooling tower maintenance plan to ensure that bacteria levels are kept low. Corrosion is also minimized with the proper treatment, allowing the cooling tower to work as it should without damage. Monthly disinfecting also goes a long way in preventing varying pH levels where acidic rates can increase the corrosion and the reverse alkaline levels accelerating scale deposits.
Have Regular Cooling Tower Inspections
In addition to monthly treatment, have regular inspections set in place for your cooling tower maintenance plan. This will help in revealing the presence of scale build-up and corrosion. For effective maintenance, inspect components such as the basins, nozzles, and drains.
Have Monthly or Quarterly Water Testing Mechanisms in Place
On the other hand, water testing comes in handy in checking for any levels of harmful bacteria such as Legionella. Experts can take samples of water from your tower, with tests revealing your water system’s components. Doing this ensures that your workers are safe and any other personnel that may be put in harm’s way when visiting your facility.
Perform Annual and Semi-Annual Cleaning and Winterization
Annual cleaning and winterization is the 4th step of an effective cooling tower maintenance plan that will allow you to get rid of any build-up within the system. Annual deep cleaning should be implemented for seasonal cooling towers with semi-annual cleaning working for year-long operational towers. Maintenance for both scenarios should include chemical cleaning followed by circulation for up to 24 hours depending on the cooling tower’s use. Draining and flushing are also required, allowing the tower to be emptied of all cleaning solutions.
Vacuuming is another essential part of the annual cleaning maintenance, with notable areas being the nozzles, basins, and the fill material. In addition to this, ensure the pipes are properly drained, and the tower is disinfected and sanitized. If you notice any damage to the cooling tower components, consider implementing an emergency water extraction. This will allow you to take care of any water leaks that could prove detrimental to your tower’s working system.
System Maintenance
Mechanical components are often forgotten, which is why a proper cooling tower cleaning plan needs system maintenance in its schedule. Make it a point to clean, repair and replace parts such as belts, motors, fans, and gears. Wiring in the cooling tower also requires maintenance, not forgetting the capacitors.
Components that require regular inspection during cooling tower maintenance plan
For detailed inspections during your maintenance, consider using the following checklist during these periodic intervals.
Weekly Checks
For your weekly checks, use electronic make-up or operate float to ensure that all cooling tower operations are working as they should. Check for leaks and corrosion as well to avoid damage to the cooling tower. If you operate an open cooling tower, test the water for the right levels of dissolved solids. Additionally, ensure that belts and pulleys work as they should with attention to excessive vibration in motors, pumps, and fans also essential in detecting inefficiencies in pump performance.
Monthly Checks
Monthly inspections will require you to check the motor alignment and coupling to avoid poor airflow. Be on the lookout for excessive wear and tear in motor and fan blades and ensure they are correctly fastened. Where required, adjust blowdown and chemicals in the cooling tower. Last, check the drift eliminators to ensure proper positioning is maintained and scale build-up.
Quarterly Checks
A quarterly check-in a cooling tower maintenance plan is not complete without inspection of the tower’s nozzles. If you spot any damaged nozzles, consider replacing them at this point. Along with this, inspect pulleys and belts within the cooling tower. Confirm that all bearings are lubricated as needed to prevent corrosion and damage of metallic components. If the gear reducer box’s lubricant levels are low, fill them up to the required rate.
Annual Checks
The last part of an effective cooling tower maintenance plan calls for cleaning the strainer in the sump. In addition to this, deep clean the hot deck while checking for rust, film, or corrosion. Make it a point to remove scale in the tower fill, change the oil in the gearbox if needed, and inspect fan blades for damages. Lastly, do a vibration analysis on the fan motor and compare the baseline values.
The Importance of Legionella Prevention
Prevention of Fatalities
Legionella has been found to cause deaths where patients fail to see a doctor after inhaling aerosols filled with bacteria. Where proper water conditioning systems are in place, fatalities can be prevented, with an effective cooling tower maintenance plan being an ideal solution.
Promoting a Conducive Workplace
Work environments need to protect employees and visitors within premises containing water systems. Adhering to Legionella risk assessment practices ensures that all your personnel works in a safe workplace.
Compliance with the Law
Due to the hazardous nature that Legionella brings, health and safety regulations require that businesses with water systems such as cooling towers perform regular checks on their sites. This means monthly, annual, and semi-annual inspections depending on the use of the facility. By adhering to the proper prevention mechanisms, businesses can avoid legal costs and business shutdowns.
Tips for an Effective Tower Maintenance Plan
Regularly Check the Air Handler Coils
The air handler coils are some of your tower’s visible areas that will show signs of sludge and scale formation. When this happens, effective heat transfer becomes a problem, resulting in more water usage and maintenance. By keeping your coils clean, you can reduce electricity expenses and maintenance costs for your tower.
Ensure Adequate Airflow
Where airflow in the cooling tower is restricted, the transfer of heat from the water to the air becomes a problem and can also result in fan failure. For an effective maintenance plan, check for poor motor and fan alignment, debris at the tower’s inlet or outlet, or damaged fan blades. Replace any damaged parts and clean out any material causing any obstruction.
Keep Track of the Cycles of Concentration
To get your concentration cycles, pay attention to the ratio of total dissolved solids in the tower’s blowdown water. With the average tower having 2-4 cycles, aim for the maximum concentration cycles to ensure you regulate the scale deposit. The trick here is to reduce your water usage, allowing you to get lower levels of blowdown water.
Ensure Adequate Pump Performance
Proper pump performance is crucial in maintaining evaporative cooling in the cooling tower. Where it is lacking, aspects such as loose connections or clogged strains could be the hindrance. You can also check for cavitations or failing bearings that could reduce the tower’s tower efficiency or breakdown.
Get Alternative Sources of Water
Alternative water sources will allow you to cut back on any water cost, with the added benefit of reducing energy consumption in the environment. Consider looking at treated effluent, treated blowdown water that is reused as make-up water, and moisture recovered from the cooling tower.
The Importance of Cleaning Your Cooling Tower
Reducing Treatment Costs
While it may seem like cutting down your cleaning schedule helps you save money, this will drive your expenses high. In hindsight, irregular cleaning will leave your tower with accumulated debris. This then leads to damage, with the likely outcome being expensive repair costs. Preventing this, however, requires regular cleaning, allowing you to enjoy cost reduction in the long term.
Prevention of Scale Deposits
During evaporation, water leaves behind mineral deposits in the cooling tower. Over time, the minerals form solids that settle in the bottom of the cooling tower. These scale deposits, in turn, reduce water flow, causing inefficiency in the cooling system. Along with this, the deposits can also lead to corrosion, an aspect that ends up damaging your cooling tower. The only way to avoid this is through cleaning and treating your cooling tower to ensure optimal pH balance and the prevention of scale deposits.
Prevents the Growth of Microorganisms
Microorganisms such as bacteria and algae thrive in warm conditions, which cooling towers often provide due to warm water in the tower. If your cooling tower is not cleaned, these microorganisms will flourish, with the growth of a bacteria-filled biofilm, following. Legionella also thrives in such conditions, which, as previously mentioned, is lethal when exposed to workers. Incorporating cleaning will help prevent any of this from happening, allowing you to continue operation without any interference.
Conclusion
Having a cooling tower hidden out of sight can be attributed to the laxity that comes with cleaning it, allowing health and structural hazards to develop slowly. Avoiding this calls for proper practices, an aspect that a cooling tower maintenance plan can help with. By relying on the various checks in your maintenance plan, you are assured of preventive mechanisms that will benefit your facility in the long run. Additionally, you also benefit from cost reduction, leaving you with better financial mechanisms to run your premises. Rather than let your cooling tower be the cause of impending threats, consider the above cleaning and treatment measures.