Preventing Combustible Dust Explosions

Dust explosions are lethal. When a cloud of dust ignites, it creates a fireball that can cause serious damage and take lives. Combustible dust has caused explosions all over the world in all types of facilities, from sugar processing plants to coal mines. Any time dust collects, explosion is possible.

So how do you prevent combustible dust explosions?

Preventing explosion is simple: you have to remove one or more of the five factors that lead to dust explosions. One of those factors is an ignition source. A common ignition source in dust explosions are system components that are out of alignment. For example, belts or bearings that are inefficiently situated can overheat.

Taking moving parts like these out of the equation significantly reduces possible ignition sources. Pneumatic conveying keeps moving parts to a minimum. Fewer moving parts mean less friction and less risk.

Nol-Tec can help you reduce risk even further by eliminating oxygen from convey lines and replacing it with inert gasses. We also take steps to prevent dust from accumulating. By taking these three steps, we remove three of the five factors necessary to create an explosion.

For more information about preventing combustible dust explosions, contact Nol-Tec at 651-318-2438.

Combustible Dust: Preventing Accumulation

Dust explosions happen when five factors are present:

  • Oxygen
  • Ignition source
  • Dispersion of dust particles
  • Confinement of a dust cloud in a small space
  • Combustible dust

When dust gathers, it can become volatile. This applies to virtually any type of dust. Explosions have happened at flour mills, sugar processing plants, coal mines and even custard factories. For any application that can create clouds of accumulated dust, explosion prevention measures are absolutely necessary.

Removing one or more of the five elements of a dust explosion is essential. The dust is the fuel for dust explosions, so preventing dust from accumulating is a very important aspect of explosion mitigation. Dense phase pressure or vacuum pneumatic conveying help to move product through convey lines without causing it to break down – which means the material can move through the convey lines without creating a lot of dust.

It’s also important to make sure dust doesn’t collect in covey lines. Nol-Tec’s unique Air Assist technology moves material past critical chokepoints where dust accumulation is common.

To learn more about combustible dust mitigation, contact Nol-Tec today at 651-318-2438.

Minimize Dust Explosion

The site of the Washburn “A” Mill, which exploded in 1878, is not far from Nol-Tec’s Lino Lakes headquarters. Situated along the Mississippi river in Minneapolis, the Washburn “A” Mill was the largest flour mill in the world when it was destroyed by a cloud of dust that ignited. The explosion not only brought down the “A” mill – it also brought five other mills down with it. 18 mill workers died.

In the 19th century, the technologies we use to minimize dust explosion risks simply didn’t exist. Unfortunately, dust explosions still happen in facilities where dust collection equipment is not well maintained or not up to date.

That’s why the Nol-Tec team is working hard to get out the message that dust explosions – and the deaths they cause – are preventable.

How to Minimize Dust Explosion Risk

At Nol-Tec, we’ve discovered that commonly-used explosion panels, venting systems, and explosion suppression systems help to mitigate explosions, but cause a whole host of other inefficiencies. For example, suppression systems use a chemical agent to stop explosions in convey lines. But the chemical contaminates the convey lines, which means all materials have to be tossed out and the convey lines have to be scrubbed. The result: downtime and increased costs.

Our team has worked hard to find better alternatives that both mitigate explosion risk and help keep plants up and running. One innovative solution is to use inert gasses, rather than oxygen, in our convey lines. Since oxygen is one of the 5 elements necessary to create a dust explosion, removing oxygen removes the risk!

For more information about preventing dust explosions, contact Nol-Tec Systems at
651-318-2438.

A Behind-the-Scenes Look at Nol-Tec

Nol-Tec Systems was established in 1983, and has since grown to be one of the most knowledgeable solution providers in the dry bulk materials handling industry. We balance the technical expertise of our staff with original ideas in order to provide custom-engineered pneumatic conveying solutions, bulk material handling, dry sorbent injection and emissions control solutions, and integrated control systems.

Our customers are industry leaders, and come in a variety of sizes and industries from small foundries to multi-national food manufacturers. Our work ranges from projects with large utilities for mercury abatement, to pneumatic conveying systems for plastic pellets, to pneumatic material handling for proppant (frac sand) suppliers, and more. We can handle dry bulk materials quickly, efficiently, and with a system specifically designed for your particular needs.

The diversity of our employees is one of our biggest assets. Collectively, they have more than 100 years of experience in the industry, and have handled countless materials in a wide variety of applications. Our staff members provide excellent service to fulfill your ever-changing project needs.

Learn about Nol-Tec’s passion for partnership with our customers and how our exceptional staff makes the difference in handling success for them by watching our new introductory video.

Introduction to Nol-Tec Systems

 

 

Test Results for Mercury Abatement Trials

In our last two blogs, we’ve discussed the evolving mercury abatement market, some of the challenges presented, and the technology Nol-Tec has developed – our Gen 3 system – to meet those challenges. We’ve had proven success with these new systems – proven through our on-site testing program.

Utilizing a large fleet of portable, self-contained testing equipment, Nol-Tec ran tests on site of both power plants and industrial boilers, in real-world conditions. Most tests were for mercury compliance with MATS standards. However, EGUs and IBs also wanted to control SO3 emissions that are not directly included in MATS, but necessary nonetheless for enhanced Hg removal.  Many tests included injecting both alkaline products and Hg sorbents. This helped us prove not only that Nol-Tec’s systems can produce the correct levels of mercury abatement, but also provide the flexibility our customers demand.

At multiple test sites, Nol-Tec proved again and again that our Gen 3 could meet the challenges presented by powder activated carbon (PAC) and mercury abatement standards. We used a variety of PAC formulations, as well as mixing different kinds of sorbents with PAC to meet requirements. We ran systems at higher injection rates than a standard eductor system could handle. We worked with fluctuating pressures (a reality in pneumatic conveying) and long convey distances. In every case, we were able to bring mercury and other pollutant levels into compliance with EPA standards, efficiently and effectively.  PAC and activated carbon injection do work for mercury abatement when used with a correctly designed pneumatic convey system.

More test result details can be found in the August 2014 issue of Air Pollution Control Magazine or on our website at this link. And you can get more information about Nol-Tec’s ACI systems at this link.

Flexible Technology for Mercury Abatement

In our last blog post, we discussed the evolving mercury abatement market, use of powder activated carbon (PAC), designer sorbents and some of the challenges that activated carbon injection (ACI) presents to utilities and industrial boiler owners. Ideally, power producers need a system that allows them to inject any sorbent they want, at whatever rate they want, through a system convey routing that they choose.  And of course, reliability is critical to the success of meeting MATS.

Since that last post, we’ve added a short primer on what mercury is, how it effects us, and methods of treatment. View that document under our Technical Information tab.

Eductor technology has long been a standard in ACI technology. However, an eductor system will not perform reliably if the system pressure exceeds 3 PSI.   Higher injection rates, longer conveying distances, and the use of designer sorbents will dictate that an alternative be utilized.

A viable alternative to the eductor design incorporates the use of a zero clearance rotary airlock (RAL) to meter product into the dilute pressure conveying system.  The zero clearance RAL greatly improves the feeding of PAC due to reduced leakage.  This technology provides a slight increase in system pressure capability, up to 6 PSI.  However, this design is not entirely reliable at the top end of its pressure range.  Some RAL leakage will still occur and material abrasion (especially with some designer sorbents) can reduce the life of the RAL.

By listening to customer needs, Nol-Tec Systems has designed and innovated a convey system which is able to meet the need to convey higher rates, longer distances, and different sorbent types. This pressurized continuous transport system provides the capability to meter material at system  pressures up to 12 PSI.  Nol-Tec’s Gen 3 systems meet the mercury abatement challenges our customers are facing.  For further information, visit our ACI web page.

How do we know we’re meeting our customers’ needs? Because in 2013, Nol-Tec invested a lot of time and effort in to field testing. Next post, we’ll discuss some of those test results.

The Evolving Mercury Abatement Market

Due to the increasingly stringent EPA regulation on mercury and the many variables surrounding in-duct capture technology, the mercury abatement market continues to change and grow. Injecting powdered activated carbon into flue gases is showing proven results in meeting the increasing compliance  standards for mercury abatement.

But because the EPA standards regulate emissions on many pollutants, technology must be able to handle activated carbon injection (ACI) and a combination of other non-carbon designer sorbents (e.g. amended silicates). These designer sorbents are being developed with finer particle sizes and unique chemistry  so as to increase removal rates not only for mercury abatement, but for SO2, SO3, HCl, and HF as well. The physical material handling properties of the new sorbents impact the pneumatic conveying system design. ACI/sorbent injection rates are being increased to meet the newest compliance standards. There is also an increasing demand for longer conveying distances, so as to allow placement of multiple silos in one offloading location. Therefore, the ACI system must be designed properly to convey various sorbents, at increased injection rates over longer distances. For further information on ACI, check out our web page at this link.

Nol-Tec has been working to meet these new challenges. In our next post, we’ll take a look at technology developments that are allowing energy producers (utilities and industrial plants) to meet mercury abatement standards, while addressing these other issues.

 

Dry Sorbent Technology for MATS and MACT Compliance

The EPA has instituted stringent regulations for both utilities and industrial boiler operators for the mitigation of air pollutants. Deadlines are approaching in both MATS and MACT and users must work with trusted suppliers to develop cost-effective solutions. Nol-Tec can provide dry sorbent injection (DSI) systems that meet both effectiveness and time frame considerations.

DSI uses a pneumatic conveying system to inject dry sorbent materials into system ductwork in a controlled manner. The pollutants in the plant emissions interact with the sorbent chemicals and become inert or non-polluting. DSI is an industry standard for mitigating sulfur trioxide or SO3. It is now also being applied effectively to sulfur dioxide (SO2), mercury (Hg), and hydrochloric acid (HCl) emissions.

One very attractive reason to use DSI is that it can be a low capital cost solution. It allows utilities and industrial boilers to supplement their current mitigation systems affordably – or to use DSI as an interim solution until larger, more costly solutions can be evaluated and installed, if needed.

Additionally, DSI systems can be quickly installed and started up. Often, the time frame from purchase order to commissioning is less than one year. This relatively quick project execution can allow energy generators to quickly meet the latest EPA standards – an important factor as deadlines draw near.

There are numerous variables to be considered to determine if your system is a good candidate for successful DSI mitigation. Removal level requirements, boiler size, flow rate, and sulfur levels in the fuel if coal is being used are only a few points to take into account. Nol-Tec has been specializing in DSI systems – design, testing, installation, and operations – for years. We can help you make the right decisions for your operation, your mitigation requirements, and your budget.

What is Resistive Splitting and Why Use It?

For utilities and industrial boilers, capital costs are one large consideration when installing air pollution mitigation. However, ongoing maintenance and materials costs can have an even great impact over time. Dry sorbent injection (DSI) systems keep capital costs in check, but sorbent effectiveness must be boosted for cost effectiveness. Here’s where Nol-Tec’s state-of-the-industry resistive splitter design comes in.

Our innovative Sorb-N-Ject® system designs make the most of sorbent materials. With our resistive splitter technology, sorbent materials do not take the path of least resistance and are instead dispersed equally through each injection lance. Non-resistive splitting, on the other hand, leaves gaps in the sorbent flow, so pollutants may or may not interact with the chemical. The process of resistive splitting fills the duct with a consistent flow of sorbent, so flue gases stream through a curtain of sorbent. This ensures maximum contact between gases and sorbent, which results in efficient chemical interaction and mitigation—and decreases sorbent usage.

Nol-Tec’s in-house experts developed this resistive splitting technology, based on our 30 years of experience in the pneumatic conveying industry. Resistive splitting increases the effectiveness of your sorbent, decreasing overhead costs. It reduces abrasion on the equipment, so a broader range of sorbents can be considered, while lowering your maintenance costs. And we’ve designed it to install easily at the main convey pipe, which lowers the costs to begin using the technology.

Remaining competitive today means keeping costs down and efficiency up. With the innovation and proven success of resistive splitting, that’s exactly what Nol-Tec helps you achieve.

Please Contact Us for more information and be sure to read our blog about DSI Regulations.

Food, dairy, and pharmaceutical manufacturing

Food, dairy, and pharmaceutical manufacturing can demand strict sanitation, rigorous materials cross contamination concerns, and precise measurement of ingredients. Properly designed dry bulk materials handling equipment can play a major role in meeting these requirements.

Every step of the process is important, and the conveying system design should be executed so that you’re working efficiently and keeping costs as low as possible. Limiting wasted ingredients is a key to success in cost containment. It’s also important that your system designer understands the flow properties of ingredients and how dry materials will react with certain equipment. Some material transfer methods can cause material breakage or compaction. Either condition negatively impacts your system’s efficiency.

Dense phase pneumatic transporter conveying systems can ensure precise measurement of ingredients, efficient transfer throughout the process, and work to minimize product attrition. Ingredients are valuable – so using the right equipment can help provide their most efficient use.

New Technologies

New technologies such as conveying line air injection and pneumatic blending result in an improved batch quality. Keeping materials moving without blockages is key. And air injection, such as Nol-Tec’s Air Assist, makes sure that materials flow reliably by distributing conveying energy throughout the system to avoid potential obstructions. Advanced blending cone technology uses compressed air to mix ingredients together with minimal material degradation and equipment wear.

Automation

As previously mentioned, in the food, dairy, and pharmaceutical industries, it’s required that the ingredient measurements are precise, and that all materials are blended properly. With the use of an automated system, this consistency is guaranteed, and leaves minimal room for error. In addition to accuracy, automation reduces expenses related to labor and the cost of ingredients, offers reporting of ingredients weights and variances, and can be programmed to meet your production needs.

Nol-Tec Systems has more than 30 years of experience in dry materials handling – so we know how ingredients flow. Every decision made impacts your end result, and our knowledge and expertise can aid in creating a system design for your specific needs.