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New Tech: Water Reuse at Power Plants through Vapor Catching

At Waterline Controls, we understand the challenges faced in industry when it comes to the responsible use of water, especially when there are millions or billions of gallons involved. That’s why we were happy to see the innovative solution created by MIT researchers that deals with the problems of water reuse involving thermoelectric plants.

The Problem

Fossil fuel thermoelectric plants, which produce about 90% of our power here in the US, consume billions gallons of water per day. These plants depend on water to provide the steam to drive the electricity-generating turbines and to keep the plant cool. According to USGS, 99% of that water is surface water and most of that is freshwater extracted from rivers, lakes, and reservoirs. Reuse of that water is vital, but can be very difficult.

An Innovative Approach to Water Reuse

MIT researchers Dr. Maher Damak and Dr. Kripa Varanasi have developed an innovative way to use the water consumed by thermoelectric power plants more responsibly, as published in Science Advances. Their focus is on the water that escapes through the cooling towers. Keep in mind that the cooling towers are an integral part of keeping plant temperatures under control.

How it Works

As water vapor leaves the massive cooling towers, a beam of ions (electronically charged particles) passes through the vapor cloud. These ions cause the water droplets within the vapor to become charged. Those droplets are then attracted to a metal mesh placed over the top of the cooling tower. The mesh traps the droplets. After the trapped droplets are collected, the water can be reused. The power plant can reuse the reclaimed water, or it can be a source of potable fresh water for coastal cities (many of which use seawater to cool their thermoelectric power plants).

How it is Different

This isn’t the first time that an attempt has been made to use a mesh to capture water exiting as vapor from the cooling towers. However, previous designs have been incredibly inefficient, capturing maybe 3% of the potential water vapor escaping. Strange as it may seem, the problem with these previous mesh designs was an aerodynamic one. The mesh acts as a flow barrier, and the water vapor flows around it. Damak and Varanasi’s solution, however, attracts the flow of vapor to the mesh by electrically charging the droplets, so they are drawn to the mesh, which has a small voltage applied to it. Also, the droplets are attracted to the wire itself, and not the holes.

Testing

A full-scale test version of the device will be installed on the cooling tower of MIT’s Central Utility Plant before fall of this year. It is easy to integrate into existing equipment and does not require any significant modifications. The purpose of this test is to “de-risk” the technology so that power companies, which tend to be quite conservative when it comes to new technology, will be more comfortable considering it.

Working With Water Responsibly

Here at Waterline Controls, we are committed to the responsible use of water, one of our most precious natural resources. Because of that, we remain committed to providing technology that supports water conservation. For example, our cooling tower water level sensors and controls prevent the loss of water by providing reliable solutions to the failure/overflowing of the float valves. Our controllers are designed for 99% reliability at a 15-year life cycle. They are modularly designed so that if one component fails, only that module needs to be replaced — not the entire unit. And our electronic sensor design uses just a small amount of power, is far more dependable than float switches, and will not degrade, foul, or plate. The characteristics make our controllers an environmentally friendly, reliable solution to water conservation problems.

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Cooling Towers & Water Conservation

At Waterline Controls we are always pleased to hear about progress being made in green technology and environmental conservation. That’s why we wanted to share the great news about Infinite Cooling’s first-place win at the Houston-based Rice Business Plan Competition. Their victory is a major win in one of our nation’s largest startup competitions. Infinite Cooling’s eco-friendly design was voted number one out of a total of 42 very competitive entries. Their innovative design would enable power plants to capture and reuse water that is usually lost through their cooling towers.

Combining Water Conservation and Power Generation

Infinite Cooling is an alum of MIT’s delta ν startup accelerator and was co-founded by Karim Khalil, Kripa Varanasi, and Maher Damak. Their mission, according to the Infinite Cooling website, is to “provide novel technology to enable water-sustainable thermoelectric power.” In layman’s language, they want to help power companies use less water while still producing the same amount of power. Their recent win at the Rice Business Plan Competition was based on the presentation of an innovative solution to water consumption at power plants: a way to capture the enormous water vapor plumes as they exit power plant cooling towers.
As the name implies, the purpose of a cooling tower is to provide evaporative cooling. Part of the water is evaporated to cool the rest of the water. As a result of the evaporation, water vapor escapes the towers in a massive plume, and the cooling water must be replenished to make up for this loss. That’s where Infinite Cooling and their state-of-the-art solution comes in.
Their dome-shaped device made out of what looks like a mesh material and is retrofitted onto existing cooling towers. The device uses electric fields to charge water and then use that charge to redirect the exiting water to a collector rather than allowing it to escape into the atmosphere. This allows a significant amount of water to be captured for reuse, thereby reducing the water consumption requirements of the power plant by 20% to 30% and can capture 100% of the vapor plume. The water savings from implementing this technology could prove crucial in areas prone to drought and water shortages, such as certain parts of California.

Conclusion

We know that our environmental resources are critical. Because of that we aim to provide technology that supports water conservation and greener alternatives to traditional water level control technology. For example, our cooling tower water level sensors and controls prevent the loss of water by providing reliable solutions to the failure/overflowing of the float valves. The electronic sensor design is far more dependable than the traditional mechanical float switches and will not plate, degrade, or foul. Our controllers have a modular design, so that if a component should fail the entire unit does not need to be replaced. In addition, WLC controllers are designed for a 15-year life cycle at 99% reliability. All of these features combined provide a green solution to your water level control needs.

Commercial Cooling Tower Water Level Control
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Additional Measure Continue to be Looked at to Combat Legionnaires’ Disease

Additional Measure Continue to be Looked at to Combat Legionnaires’ Disease

Under typical operating conditions, cooling towers can propagate Legionella. Combining chillers and plastic surface cooling towers with added anti-microbial options can significantly reduce the infection risk.

NSF P453: Cooling Towers – Treatment, Operation, and Maintenance to Prevent Legionellosis

This protocol outlines proper maintenance and safety practices associated with evaporative cooling systems. It’s a simple plan with specific means and procedures to manage risks of Legionnaires’ disease. Also addressed are several health concerns associated with commercial buildings and health care facilities. NSF P453 gives the rest of the U.S. rules similar to the New York City and state regulations for cooling towers.


Disneyland, the ‘happiest place on earth’ was required to shut down two water-cooling towers after some visitors to the Anaheim, Calif., theme park contracted Legionnaires’ disease.

12 cases were discovered ‘about’ three weeks ago by the Orange County Health Care Agency.

Disneyland was informed of the cases Oct. 27. After testing found two cooling towers had high levels of Legionella bacteria, the towers were taken out of service and disinfected. They were put back in operation Nov. 5 but, but were shut down again 2 days later. At this point, tests will be required to confirm they are free from contamination, according to the park and the county health agency, before they will be put back in service.


The New York City Department of Health, while investigating an outbreak of Legionnaires’ disease in the middle of October that infected 15 people, took samples from 55 cooling towers in the area of the reported outbreak. Preliminary results determined that 10 cooling towers contained Legionella DNA. The Department has issued orders to increase or change the biocide used to the kill bacteria.

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Austin, Texas Cooling Tower Registration and Update Deadline Nearing

Austin, Texas Cooling Tower Registration and Update Deadline Nearing

The 2015 Uniform Mechanical Code and 2015 Uniform Plumbing Code (UPC) for the city of Austin, Texas includes a deadline of December 31, 2017 for registration of all Cooling Towers in the city. There are several specific rules that require upgrades to most older towers.

Section 1126.0 of the city’s UPC requires all properties with cooling towers to register them with Austin Water.

The City ordinance requirements include:

  1. Make-up and Blow-Down meters.
  2. Conductivity Controller.
  3. Drift Eliminators with a drift rate of not more than 0.005% of the tower circulating rate.
  4. Cold water basin high level alarm.
  5. Must operate at a minimum of 5 cycles of concentration.

The City ordinance requires that cooling towers must have a cold water basin high level/overflow alarm. For cooling towers of 100 tons or more, the make-up and overflow meters, and the over flow alarm shall be connected to the building’s Central energy Management System or Utility Monitoring Dashboard.

WLC 6000 SeriesWhat this means is that all towers need a modern system with alarms and sensors that can connect to a BMS. Waterline Controls model WLC-6000 Cooling Tower Water Level Controller is our most popular model for providing a high level alarm, make-up water control, low alarm and a low water level cutout.

Waterline Controls has the system to retrofit and get you compliant fast. Our Stainless Steel Electronic sensors and solid state software driven controllers offer the connectivity, accuracy and reliability you need. With a multi-wire connection for you BMS or Building Automation, we have you covered.

Commercial Cooling Tower Water Level Control
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Cooling Tower News Updates

Cooling Tower News Updates

100s Of Cooling Towers Examined After Melbourne Legionnaire’s Disease Outbreak In March That Had Six Confirmed Cases

Cleaning of large amounts of cooling towers in Melbourne Australia were undertaken after Victoria’s Department of Health and Human Services confirmed the outbreak in the Central Business District.

Just a few months ago there was discussion about many of Melbourne’s new apartment buildings posing a legionella bacteria risk due to their energy-efficient “warm water” systems.

$42 Million Cooling Tower Replacement At Nuclear Plant Being Proposed For Closure

Palisades Nuclear Power Plant

Palisades Nuclear Power Plant, which according to WBFO has divided some residents in the area of Van Buren County in Michigan over its proposed closure, is replacing a cooling tower over the next 3-4 months. While the plant may be closing down, maintenance and upkeep will continue to be an ongoing job for quite some time.

Decommissioning and cleaning up a nuclear plant can take over 50 years. The Michigan Public Services Commission will host several public meetings in May before deciding on the final outcome of the plant. Economic impacts may be hard on some of the surrounding communities as the plant employs over 130 people.

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Is Your Cooling Tower as Safe as You Think?

Is Your Cooling Tower as Safe as You Think? Is Stricter Oversight the Answer?

Legionnaire’s Disease

Legionella bacteria, the source of Legionnaire’s Disease, has been repeatedly found in inspections of cooling towers after outbreaks. Many areas are turning to tighter rules and more vigorous inspections of cooling towers as a way to prevent outbreaks.
Public officials and building owners are being held to answer for the outbreaks, with various systems being looked at to help provide answers.

Accountability

According to an AP report on March 13th, an ex-Flint Michigan Official was given probation for neglecting to report a Legionnaire’s outbreak that occurred during the much publicized water scandal there last year.

Some areas have stepped up inspections, while others have added fines and new rules. Some areas have also stepped up educational resources and outreach to help those who manage facilities become more acutely aware of the needed precautions and maintenance procedures needed.

Seeking Answers

Operating procedures, maintenance, and cleaning are critical in preventing growth of the bacteria that cause Legionnaire’s disease. Due to changes in technology over time, many older buildings can also benefit from newer systems.

Educational outreach directly to owner of buildings is a benefit of cooling tower registration systems being tried in some jurisdictions. Such information can be critical in supporting owners, who are ultimately responsible for the maintenance their buildings.

The Centers for Disease Control and Prevention reports that “…about 5,000 cases of Legionnaires’ disease are now reported each year in the United States.” Luckily there is some good news on the recovery side. Legionnaires’ disease is most often non-fatal today, thanks to better detection and treatment of the disease.

In an article at the Charleston Gazette-Mail, Janet Briscoe at Kanawha-Charleston Health Department stated “People are getting treated sooner. It’s identified sooner, so the rates of death are a lot less than what they were in the past.”

Newer technology, better education and closer oversight of cooling towers are all coming together to prevent illnesses due to Legionnaire’s Disease.

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Cooling Towers found with Legionnaire's Disease in New York

Cooling Towers found with Legionnaire’s Disease in New York

New York City has announced that 2 more people have died from Legionnaire’s disease, bringing the casualty total to 10 so far, of the one hundred people infected in the South Bronx.New York Rooftop Water Tanks
Five separate cooling towers have so far been identified as being infected, since the outbreak started last month.
Even though New York Mayor, Bill de Blasio has said he was confident they have identified all sources of the current outbreak, he has also ordered all cooling towers in New York be inspected within the next 2 weeks. The logistical nightmare of this should keep inspectors quite busy for awhile. Anyone who owns or manages a building utilizing a cooling tower is required to test and if needed disinfect it. Those who do not do so will be subject to misdemeanor charges for failing to promptly comply.
The Mayor, in an attempt to settle those with public safety concerns said “I want to emphasize at the outset that the vast majority of buildings in New York City do not have these cooling towers.” He continued with details of the scope of the issue “They tend to be found in bigger, more modern buildings, but any building that does have one of these cooling towers will be subject to this order.”
Keeping a cooling tower safe and free from bacteria or other contaminants is very important. Cleanup requires soaking the cooling tower with chlorine for 16 hours, draining it, and then scrubbing it clean.
According to Rich Parker, the president of a cleaning company dispatched to the Opera House Hotel, “The water circulates wholly within the tower and does not come into contact with air conditioning units.”
“The air conditioning units is a whole separate water system.” He expressed confidence that the system was safe and that the cleaning was because they required it, not because there was any bacteria found or suspected at the Hotel.
Four cooling towers in the South Bronx tested positive for the bacteria and were fully cleaned already. Although Mayor de Blasio says he is confident that the disease cannot be spread through drinking water, cleaning specialist know that the bacteria can breed wherever there is standing warm water that has the possibility of being inhaled as a mist. According to certified water technologist Steven Serrano, as reported by NY1’s Erin Clarke “Legionella Pneumophila thrives in a temperature between 77 degrees all the way to 115.”
The outbreak once again reminds us upkeep and maintenance of your cooling tower is of the utmost importance. The damp and warm environment that the bacteria needs to thrive is found in cooling towers, which must be cleaned regularly to prevent the bacteria from taking root.
Dr. Jay Varma, Deputy Commissioner for Disease Control for the New York City Health Department says the city delayed creating the new regulation sooner, partly due to the trouble in identifying the cause, which he said can be difficult in many cases. He did not known how often cooling towers were the source of the disease. “The challenge is we don’t know where most infections normally come from,” he said.
Officials say they are confident that they have identified and addressed this outbreak, but have not yet determine specifically if the infected towers were the cause of the infections or if it was one or several that actually infected people, though the disease was found in at least 5 towers so far. the cleaning rush will now most likely cover up the actual spear of the disease, as many people may just clean them as a precaution while waiting for available personnel to test them. Once officials notice an increase in diagnoses an outbreak may already be underway. Legionella Pneumophila has an incubation period of up to 10 days, making tracking potentially quite difficult.
Cleaning your tower regularly and maintaining it properly is not just cost effective, but potentially life saving.

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Identifying Water in Transit in Cooling Towers

Identifying Water in Transit in Cooling Towers

While our system is simple to use and install, some theories and terms can be good to review before proceeding. With this in mind, let’s talk about the ‘hidden’ water in a typical cooling tower system. The terms we will be talking about here are “Freeboard” and “Water in Transit”.
Freeboard – This is a civil engineering term used to describe the distance between the normal operating level of an environment and the space allowable to fill without overflowing any reservoir. For our purposes we will use this term to describe the distance between the minimum operating level (that is an acceptable level to allow all the other features and functions of the system to operate properly, such as pumps and valves and piping) and the overflow level (the point at which it dumps to waste and cannot be recovered).
Water In Transit – Describes the water moving through the system while it is operating, that has the potential to get back to the basin/holding tank and filling the freeboard.

Needed Calculations

[easy_cal]

How to calculate and evaluate freeboard and water in transit
The needed space can be calculated by measuring the water in transit in gallons and then figuring how much space is needed inside the basin/tank.

  1. Calculate the volume in the pipes by using the volume of a cylinder formula where the measurements are in feet.
  2. Multiple that cubic dimensions by 7.5 (since there are 7.48 gallons of water in a cubic foot).
  3. Calculate how much water is in every inch of the tank by using Length x Width x 0.0833 x 7.5 or using the volume formula where the height of 1” = 0.0833Ft.

The rule of thumb for cooling tower water in the system is one half of the GPM of the tower.

Verification

This is a good estimate and now it should be validated by setting a level in the tank as a minimum operating level and see if there is going to be enough freeboard to capture the water in transit. We all tend to want an extra 2 or 3 inches for whatever reason so add the space if you have it. This freeboard will be required to capture this water every time the system turns off. When or if the demand changes because someone adds more piping (equals more water in transit) or more water capacity in any form then the required freeboard changes in the same manner.

Dangers of Older Level Control Systems

Corrosion capacitive sensor

Corrosion on a capacitive sensor – typical after ! year


Just because the system is adding water it does not mean that the volume of water is increasing. The water that is being added is caused by the need to dump water or water evaporating, so water in is equal to water out. Typically, setting a water level in these types of environments should not be set up on a long term basis with a mechanical float switch of any sort, you should use a system like WaterLine Controls. The reason is because float switches are mechanical and set to operate at the minimum operating level but whenever the system is turned off the float switch is stressed in the opposite direction. This occurrence over time affects the set point but also has the potential for mechanics of some float switches to fail, allowing water to run freely into the tank and out the overflow.
With our WLC System there are no floats in the water, it is a sensor driven system where the water is free to move up and down the probes and this up and down movement has no effect on the probes since they do not move. Also, with a WLC system, there is the ability to send the sensor activation points to an automation system or BAC so the set points in the tank can been “seen” electronically and acted upon, if necessary – That cannot be accomplished with a mechanical float.

Some Real World Examples

Recently, we have been running into cases where the operator is replacing an old water level controller that either had water volume control issues in the past or the demand on the system has changed because someone has added volume requirement capacity. When they go to put a WLC unit in, or for that matter any level controller back in, every time the system turns off the cooling tower basin/holding tank overflows into the drains and the excess water then goes to waste.
We have been told many stories about these catastrophic float switch failures where companies lose tens of thousands of gallons of water and thousands of dollars. This next example is where the demand had changed and the level was dropped to accommodate the change. In this case the water was set in the original design to be an air barrier so as to force all the air through the fill material. When they lowered the level that barrier disappeared and air would now take the least path of resistance under the fill between the fill and the water level. More airflow along the bottom caused the fill to dry out since there was now more airflow across this area from lower resistance. This now caused all of those other issues related to dried out fill and poor air movement through the fill reducing efficiency. The only way to make this operate as designed is to add an external tank to capture the added water in transit.

Audible Alarm
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California Cooling Towers Now Need Overflow Alarms

California Cooling Towers Now Need Overflow Alarms

On July 1st, 2014, California Building Energy Efficiency Standard’s most recent revision went into effect. One of the adjustments from the 2008 standard that was implemented was “increasing cooling tower energy efficiency and water Savings” (Section 140.4.(k)2). The updates to Title 24, Part 6 aim to improve water use and conservation in large cooling towers. According to Section 110.2(e), “Open and closed circuit cooling tower installations must … Be equipped with an overflow alarm to prevent overflow of the sump in case of makeup water valve failure. Overflow alarm shall send an audible signal or provide an alert via the energy management control system to the tower operator in case of sump overflow” (California Energy Code, p. 28). This standard is now mandatory on cooling towers 150 tons or greater.

The Waterline Controls WLC series is a perfect solution for an overflow alarm. The WLC5000 and WLC6000 both include not only a high alarm, but a low alarm as well. The units have dry contacts that connect directly to the Building Management System, as well as LED indicator lights on the controller itself and optional audible alarms. What’s more, they also function as an automated water level system that is much more reliable than any mechanical float switch. All units have an Expected Useful Life (EUL) of 15 years backed by a 5 Year Limited Warranty, matching the analysis life cycle proposed during the 2013 Standard prerulemaking (Codes and Standards Enhancement Initiative, sec 2.7.6-2.11). WLC4000, 5000, and 6000 series currently in the field meet these requirements, and no updates or upgrades are necessary.

California’s Energy Commission website states “ [Our] energy efficiency standards have saved Californians more than $74 billion in reduced electricity bills since 1977”. Waterline Controls aims to help programs like these by providing an efficient and reliable water level control system to save water not only in California, but around the world. To upgrade your cooling tower with a Waterline Controls unit, visit our website at www.waterlinecontrols.com or call our toll free number at 888-905-1892.

For more information on California’s Building Energy Efficiency Standards, visit the links below.