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Posts Tagged ‘U.S. Water Services’

Every year the cooling system for an industrial plant providing comfort cooling was shut down and drained for the winter months. Historically, during this shut down period the cooling water piping and equipment would experience severe corrosion. During start-up of the cooling system the next spring, iron flakes would peel off the piping plugging strainers and heat transfer equipment. This would interfere with the efficiency of the production process and cause an increase in maintenance. 

U.S. Water Services recommended Cooling Tower Toads to solve this difficult problem. Cooling Tower Toads would provide a Vapor Corrosion Inhibitor (VCI) protective layer that would film all the metal components not allowing oxygen and water to create corrosion cells on the surface of the metal. In addition, the VCI would coat recessed and inaccessible areas such as the vapor spaces of piping providing protection to these hard to reach areas. With the ability of the VCI to replenish coatings that are disturbed or depleted, the protection would last for the entire layup season.

One box of 2.2 pound bags of Cooling Tower Toad added to the tower basin for every 1,000 gallons of water. The cooling tower basins were drained to the lowest possible operating level to reduce the amount of water that needed to be treated. A non-ionic biocide was added to sterilize the system as a routine maintenance practice prior to shut down. 

The Cooling Tower Toads were removed from their outer bags and directly added to the tower basin. The inner poly-alcohol bag dissolved in approximately 5 minutes. The system was recirculated for 8 hours and then drained.

Inspection of the cooling system piping and heat transfer equipment showed a very noticeable improvement in the inhibition of rusting and corrosion thus reducing maintenance and increasing efficiency.

Consult your U.S. Water Services representative for Cooling Tower Layup Guidelines, as well as to see how the Cooling Tower Toads can help you minimize corrosion in your system by contacting us at 1-866-663-7633 or info@uswaterservices.com.

 

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U.S. Water Services is always looking for new tools to make your facility’s boiler system more efficient. One of the tools is a U.S. Water Services boiler inspection. What is a boiler inspection you may ask? It is a thorough checkup of your internal and external boiler components in addition to the mandated inspections.

Boilers can be dangerous if not inspected and maintained properly. Each year, countless accidents, breakdowns and unnecessary shutdowns occur among industrial boilers. While boiler safety devices are designed to prevent dangerous conditions elevating into disasters, only proper boiler maintenance prevents the development of dangerous operating conditions in the first place by finding deficiencies before they become a serious problem. In addition to loss of life, boiler accidents can cause major structural damage to plants, facilities and equipment resulting in thousands to hundreds of thousands of dollars in repair and replacement losses.

Proper boiler maintenance, servicing and inspection is not only a safety issue, but also an economic matter. Regular boiler maintenance and inspections can provide system optimization. Boilers are high energy users; inefficient operation means wasted energy and increased operating costs. A boiler accounts for a large amount of the plant’s energy budget, and even a small decrease in a boiler’s efficiency can cause a sharp increase in energy costs. Proper water treatment is a key ingredient to making sure your boiler is operating properly. Raw water impurities that occur naturally in the feedwater may cause corrosion or sediment buildup, both of which reduce efficiency. Impurities lead to wasted energy because they necessitate routine blowdowns. The cleaner the water supply going into the unit, the fewer blowdowns you’ll need. U.S. Water has a complete line of boiler water chemicals designed to keep the water clean and your boiler operating at optimum efficiency.

Regular maintenance and inspection can also help extend the life of the vessel. Boiler downtime may force a manufacturing plant to shutdown operation and production, resulting in loss of income that can add up every hour the boiler is down. No plant owner wants emergency shutdowns or equipment downtime because boilers, or other equipment, weren’t serviced or inspected regularly.

U.S. Water Services Senior Regional Manager Steve Tapper has performed various boiler inspections throughout his tenure in the water treatment industry. “There are two important reasons to have U.S. Water Services inspect your company’s boilers,” Steve said. “First, when inspected by the state, the inspector is only looking to ensure the boiler meets state safety regulations. Second, because these systems shut down once or twice a year, this is the only time we can inspect the inside of the boiler to determine its efficiency and whether any modifications need to be made.”

It is important to remember that most problems don’t occur suddenly. They develop slowly overtime. So slowly sometimes, that they can be overlooked as the maintenance staff grow accustomed to the change without realizing it has taken place.  Maintaining a boiler is much like maintaining a car; you need to do it regularly to optimize efficiency and performance so that it doesn’t break down at an inopportune time. Boiler maintenance logs are probably one of the single best methods for keeping track of boiler maintenance. Boiler logs provide a continuous record of the boiler’s operation, maintenance and testing helping identify and detect changes that may have gone unnoticed.

Contact a U.S. Water Services Representative to find out more about how our Boiler Inspections can help you with prevent issues before they become problems. All of our boiler inspections follow these guidelines:

  • Personal Safety Equipment based on your procedures and ours.
  • Proper “Lockout” Procedure for boiler.
  • Inspect the steam drum from the generating tubes to the chemical feed line.
  • Inspect the bottom drum from the drum surfaces to the blowdown angle iron.
  • Inspect the fireside of boiler including but not limited to the furnace wall tubes, convection sections, superheater and refractory searching for deposits, blisters, alignment, and supports.
  • Check the headers, if present for deposits.
  • Inspect the deaerator including the storage section, sprays and trays.
  • Inspect other equipment such as the turbines, pumps and pretreatment equipment.
  • Document the results in an easy to read detailed report.
  • Set up meetings to discuss the boiler inspection’s results with you, the customer.

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Visual inspection of chiller and evaporator tubes is a great tool to determine the effectiveness of a water treatment program. Effective use of a borescope can visually determine if a water treatment program is preventing scale formation, copper corrosion and biological fouling. Used in conjunction with an Eddy Current study, any tube defects can normally be seen visually with the use of a borescope. Pictures and videos can also document the conditions of the tubes.

When Should You Borescope Your Condensers and Evaporators?

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New condenser tube with a lateral tube defect.

U.S. Water Services recommends all new condenser or evaporator tubes be Eddy Current and borescoped to establish an initial point of reference. Figure 1 shows a tube defect in a new chiller before it went into operation. Early detection allows for tubes to be replaced prior to starting the equipment preventing potential early tube failures.

 

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Condenser tube showing biological fouling and deposits

 

After the initial inspection, scoping should be done yearly on condenser tubes and every two years on evaporator tubes to track the progress of the effectiveness of the water treatment program. This allows documentation of the tube conditions. Figure 4 shows early signs of biological fouling and deposition on the hot side of the tubes that would normally have been missed during inspection without the use of a borescope.

What Is The Difference Between A Borescope Study And An Eddy Current?

Eddy Current studies determine if there is any metal loss due to corrosion or defects. Eddy Current studies do not provide a visual picture of the tube surfaces. The value of the borescope study is to observe the amount of scale formation and surface corrosion that could lead to future permanent tube damage.

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One of the most overlooked, yet costly issues facing many plants today is the presence of an ineffective water treatment system. This can often become a financial burden. A midwestern food processing company was experiencing problems with their water system. Facing continued expenditures, the company decided to have U.S. Water Services design an integrated water treatment solution for their old system. Through U.S. Water’s unique integrated approach, combining mechanical and chemical solutions in-house, we understand the balance between the two and how changes in one can affect the other. As a result, after a system survey, U.S. Water recommended four major improvements to the water treatment and feedwater systems that enabled the customer to experience a dramatic Return on Investment (ROI).

The four steps are summarized below:

1) The installation of a reverse osmosis (RO) system resulted in a 96% improvement in the quality of water fed into the boiler system. This resulted in:

  • Reduced amount of water drained from the boiler during blowdown. This saved a calculated total of $5,281 in water and sewage costs annually for this particular plant. 
  • Reduced the amount of fuel wasted in blowdown discharge. By decreasing the amount of blowdown, the system wasted less energy, which reduced fuel costs annually. 
  • Maintain acceptable corrosion rates in the condensate system, while complying with the company’s requirements regarding the feed of steam-lined treatment. Steam-line treatments are not allowed at this facility, so the condensate system was experiencing unacceptable corrosion rates. By removing the majority of alkalinity in the boiler make-up water, the RO system greatly reduced corrosion in the condensate piping.
  • The switch to high purity RO treated make-up water allowed the implementation of an advanced polymer chemistry boiler water treatment. Dramatic improvements in boiler tube cleanliness were evident within six months of making this change. Removing old scale from the heat transfer surfaces will greatly increase boiler efficiency, resulting in tens of thousands of dollars in annual fuel savings.

2) The replacement of a feedwater heater with a deaerator provided the system with a mechanical removal of over 90% of the oxygen in the feedwater. The chemical oxygen scavenger demand was reduced significantly. In addition, operator handling of all boiler chemicals was eliminated through implementation of our EZ Feed chemical delivery and storage system.

3) The entire boiler chemical feed system was automated, including chemical feed, boiler blowdown, and chemical handling. This state of the art boiler chemical feed system provides the following benefits:

  • Tighter control of boiler blowdown resulting in improved fuel efficiency
  • Improved boiler chemical feed, with consistent results that will lead to boiler efficiency savings and reduced chemical usage.
  • Complete containment of all boiler chemicals. The operators have virtually no contact with the water treatment chemicals. This improves operator safety, and reduces waste with the elimination of chemical drums.

4) Improved operation management of the boiler water treatment program by company maintenance personnel. None of the above improvements would be realized without these efforts. Though the systems are automated, they still require attention to ensure correct operation. This includes:

  • System tested regularly to ensure proper operation
  • Adjustments made to maintain service parameters
  • Conduct preventative maintenance to ensure the components of the new feed system are properly cared for.

U.S. Water Services designed an integrated water treatment plan specifically aimed at the needs of the company. Our exceptional engineering department is capable of creating an integrated system engineered to fit your company’s needs. 

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Water Use For Ethanol Production: Where Are We Today?

posted Wednesday, June 27, 2012 4:54pm

by Sara Schoenborn, Assistant Editor at Agriview

With a steadily growing global population, it has become the focus of all those involved in agriculture to learn and adapt new ways of producing more food, fiber and fuel with less natural resources. 

Last week, Todd Potas, biofuels strategic business leader with U.S. Water Services, updated attendees of the 2012 Corn Utilization and Technology Conference in Indianapolis as to the water use optimization within current ethanol facilities in the United States.

Water is a key component to the ethanol producing process, Potas said, noting that some of the properties that make it so are its abundance, it holds heat, it is low cost, it has great propensity for holding chemistry and most importantly for dry grind ethanol, it allows for fermentation. You can remove the heat with evaporated cooling and it also allows for separation through things like distillation,” he said.

“The biggest and most difficult issue with water is that you must maintain sustainability with it.” Potas continued. “It’s very critical to appreciate the resource and understand the resource and what you have available to work with. Discharge regulations are constantly changing and it’s a very dynamic environment.”

In an effort to avoid issues such as contamination and green house gas emissions, Potas said the ethanol industry is trying to take advantage of the natural hydrologic cycle (evaporation, condensation, precipitation and so forth) when using water for processing.

“Wherever we take the water from, greatly affects the quality of that water,” he said. “Lakes, streams-anything on the surface is typically the softest water available. As you go into the ground for well water, that water becomes hard and picks up contaminants.”

In terms of gallons of water per gallon of ethanol produced, there’s a lot of information available today, Potas noted, adding that 1.5 gallons of water per 1 gallon of ethanol produced is the goal number.

“I think it is possible,” he said. “In the older facilities – anything pre-2000 – they were doing about 4.5 or 4.6 gallons of water per gallon of ethanol produced. Any of the new plants built after 2000, were doing about 3.4 gallons. All with roughly the same water quality.”

As of 2008, Potas said that number dropped to 2.85 gallons with the University of Chicago reporting 2.7 gallons in 2009.

“The progression has been very rapid as the industry has matured,” Potas said.

To put the water use levels into perspective, Potas said that when compared to some other industries, this is far less than what it takes to create even a can of vegetables, which takes 9 gallons of water per can.

“Everyone needs to use water to produce their products,” Potas explained.

“You’re seeing a pattern of increased water use to produce oil. We’re seeing a decreased water pattern for ethanol,” he added. “In fact with oil sands, the water is often extracted from the ground and pumped right back down there as waste water so it’s taking it out of this hydrological cycle we’re trying to work in. With deep well injection that water is lost to the environment.”

Conversely, he added, the ethanol industry from 1996-2006 has produced ethanol with 50 percent less water on average.

So where are we today? The benchmark, Potas said is really 2.9 to 3.4 gallons of water per gallon of ethanol produced.

“The optimized facilities that are employing some of the readily available commercial strategies are achieving 2.4 to 3.0.” he said, noting that some of the facilities that have embraced “pretty much all of the strategies that are available with integrated zero liquid discharge,” are achieving 1.7 to 2.1.

“In some cases those are the same facility – 2.1 in the summer and 1.7 in the winter when cooling is optimum and efficient,” he said. “So the predication (of 1.5 gallons of water per gallon of ethanol produced) is proving to be pretty accurate.”

Potas explained that water balance is the strategy necessary to achieve this water use in the ethanol industry.

A variety of water sources are available he said, namely noting the water available from the wells and municipalities, grey water from municipal waste water treatment plants, surface lake options (which are typically very good quality soft water) and storm water.

This water is treated to various qualities for the facility with the boiler quality being the most difficult to achieve as it requires the cleanest, purest water.

“As regulations are pushing limits lower, it’s making it more and more difficult for facilities to comply,” Potas said. “It’s really a balancing act.”

For water use in the ethanol plant, the cooling tower requires 50 to 55 percent; boiler 16 to 20; treatment 14 to 18 and the processing 12 to 16.

“We really need to appreciate where the majority of the water is going,” Potas explained, adding that they like the tower to be even a higher percentage.

By running sludge through a gravity filter followed by a filter press, Potas said the leftovers can be used elsewhere. “A landfill is your least desirable option,” he stated. “Hopefully you can use it for farm soil conditioning or fertilization or you can use it as a nutrient in the distillers grains. “

Reverse osmosis works as a semi-permeable membrane under pressure, allowing pure water to go through the membrane and the dissolved solids are held back. The pure water becomes permeate for boilers and cooling towers.

“When we look at what the payoff is for this water treatment, you can get excellent water quality,” he said.

Potas said that the best opportunity to reduce water use at a facility includes the boiler system – where 20 percent of steam can be lost at the front end of the facility.

“This water increases the amount of water you need in the process, which is detrimental to your water balance,” he explained. “If you can reduce or reuse this water it can greatly save you.”

Every 100,000 pounds of steam requires about 6,500 extra gallons of water, Potas noted. If a facility is using 20,000 pounds of steam an hour to sterilize the mash in the ethanol plant, that is 11 million gallons a year.

Boiler bleed/blow down involves relatively clean water. “It’s hot so there is energy there. This water is often reintroduced into the process,” Potas said, adding that 60 percent of ethanol facilities do this.

It is important to minimize drift in cooling towers, Potas said. You only want evaporation leaving the water tower – not water droplets. This can also help with air emissions because there are particulates in those water droplets that a facility has to account for.

“From a control standpoint, the bleed water and the water in the system are the same concentration,” Potas continued. “The tighter you can hold the control on that, the better water use you are going to have, the lower discharge you’ll have on your permit, the lower chemistry you’ll use and also the better consistency you’ll have for your system.”

New water does have to be utilized, however, because at a certain level, algae, bacteria and fungi develop in the system.

A storm water collection system – which typically has quite soft water – is beneficial because as it is used, the biological concerns (total dissolved solids) become less.

“It’s very effective to reuse this water in the cooling tower system. You may need to do a little filtration to take out suspended solids,” Potas stated.

One final option (that does require capital investment) would be to collect the water vapor out of stack, which could represent up to 4 million gallons of water per year.

“If you can get 11 million gallons from the steam injection, 4 million from boiler bleed, 20 million in cooling tower, 10 million for storm water use and if we use the condensate from the stack that’s the savings of roughly 50 million gallons of water a year,” Potas said. “We’ve gone from 3.5 to 2.5 gallons with some relatively ready, commercially available technology to tighten up the water.”

“It’s very important to look at water balance, begin planning and continually improve. This can help ethanol be more profitable, greener and more sustainable in the future years.”

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A membrane autopsy is a good description of the analysis that can be performed on a fouled membrane. It can also be the key to determining how to prevent fouling of new membranes and to maximize the efficiency of this key piece of water treatment equipment. U.S. Water Services performs this analysis in-house at our location in Cambridge, Minnesota, and then issues a comprehensive seven page report of the results. The test is destructive, and the membrane element is not returned.

usws ro membrane
RO Membrane After Completed Autopsy

The procedure begins with a physical examination of the intact element. We start by looking for physical damage to various parts of the element, including the brine seal, outer casing, permeate tube and any evidence of telescoping of the membrane. We next look for evidence of gross fouling on the leading edges of the rolled membrane in the end cap. Fouling in this area can restrict water flow through the element, and the elements behind it in the array tube. If a system is experiencing leading edge fouling, it usually occurs on the first element in each array of the first bank.

The fouling is principally a result of dissolved organic material, or fine suspended solids that have made it past the pre-filter system. Next, the element is taken apart by removal of the end caps, and the membrane is unrolled. This allows a series of specific tests to determine what has happened to this particular system. Samples of the membrane will be subjected to dye testing. The dyes are chosen due to the size of their molecules, which prevent the dye from passing through normal membranes. The dyes will pass through damaged membrane sheets, and will stain the underside of the membrane composite material.

This membrane barrier damage is often caused by exposure to halogens (chlorine and bromine compounds). We use another test, called the Fujiwara analysis, to determine if halogens have reacted with the membrane’s polymer structure. Membranes that have been damaged by other oxidants, such as permanganate, ozone, or hydrogen peroxide, will not react to this test, so it’s possible to determine what type of chemical is causing the damage.

The next step is to collect foulant off of the membrane sheet, and analyze it for chemical composition. The foulant is tested for Loss On Ignitions (LOI) to determine how much is organic material. The sample is then analyzed by X-Ray Fluorescence and X-Ray Diffraction, which provides information about the relative concentrations of specific ions, such as iron, calcium, silicon, phosphorous, or barium. An example of this type of analysis is shown below:

  • Silicon, SiO2……………………………..  9.88%
  • Iron, Feo3…………………………………  22.20%
  • Calcium, CaO…………………………….  6.28%
  • Phosphorous, P2OS…………………….  11.50%
  • Barium, BaO……………………………….  9.60%
  • Magnesium, MgO…………………………  1.00%
  • Sulfur…………………………………………  2.24%
  • Strantium, mg/l……………………………..  2.19%
  • Barite, BaSO4………………………………  16%
  • Amorphous (non Crystalline)…………….  >80%
  • Unidentified………………………………….  <5%

With the information from a complete membrane autopsy, you now have the tools to determine the best approach to prevent issues in the future. If your system is running pretty well, a membrane autopsy can still be useful to develop a baseline of results for your reverse osmosis and other pre-treatment equipment.

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Sodium zeolite softening is an ion exchange method for removing hardness from water sources achieved by exchanging calcium and magnesium ions for sodium. This process is ideal when applied to domestic, commercial and industrial water softening due to useful purposes such as filtering, odor removal and ion exchange.

When a softener with fresh resin is in service, the sodium ions in the surface layer of the bed are immediately exchanged with calcium and magnesium. This will produce soft water with very little residual hardness in the waste matter. The resin bed will continue to exchange its sodium ions with calcium and magnesium ions until the hardness concentration in the waste material increases rapidly. Referred to as the “breakthrough point” it is the point at which regeneration is needed.

The following is a typical regeneration sequence:

1. Counterflow backwash the resin. Specified rates based on temperature and manufacturer’s data. Backwashing removes surface deposits and fines, classifies resin and conditions the resin bed for proper regeneration.

2. Regenerate. Brine regeneration consists of educting saturated brine from a brine tank or other source and diluting it to generally 8% to 10% by weight NaCl. The brine should elude through the resin bed, first increasing in concentration, then reaching a peak and decreasing until only dilution water is present.

3. Rinse. The fast rinse cycle compacts the resin bed as well as rinsing the final residual brine from it.

Poor regeneration practices are often the cause of problems in zeolite softener systems. An elution study is used to identify and correct softener problems. The study plots the concentration (specific gravity) of brine from a zeolite softener during regeneration along with recording cycle times. The information is then used to troubleshoot and evaluate systems.

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