air dust purification installations

When they talk aboutair dust purification installations, many immediately imagine some kind of box with a filter inside. This, of course, is the basis, but if you stop there, you will get a bunch of problems. In fact, effective cleaning is always a system where the filter unit itself is only one of the components, and often not the most capricious. The main mistake is to underestimate the preparation of air in front of the filter and the organization of aspiration. This is where I’ll probably start.

Where does dust come from and why is it difficult to catch?

Worked with different shops - foundries, crushing plants, and bulk materials transfer areas. The main lesson: dust is different, and so is its behavior. Heavy metal dust from grinding and light coal dust are two very different things. The first can be caught with a correctly calculated flow rate in the air duct. The second is a complete headache: it hovers, penetrates into the slightest cracks, and if the aspiration system does not create sufficient vacuum right in the formation zone, then all the filters will work idle. I often see how they install a powerful filter, but skimp on covering the emission sources or on the diameter of the air ducts. The result is that dust remains in the workshop.

Another nuance is humidity. If there is moisture in the air (say, in winter or from technological processes), fine dust begins to stick together, forming clumps. This, on the one hand, facilitates capture, but on the other, it threatens to clog the air ducts and the filter element itself. It is necessary to install either heating of the tract or frequent regeneration. Without this, the installation quickly loses performance.

I remember an incident at one of the transshipment terminals. We installed a standard cyclone-hose system. The dust was from coal, it seemed nothing complicated. But they didn’t take into account that in winter the coal arrives frozen, with ice chips. That ice dust did not separate in the cyclone; it went further into the sleeves, where it melted and tightly clogged the fabric. I had to redo the intake assembly and install a flow preheater. Trifle? On paper - yes. In practice, this is a simple and expensive repair.

The heart of the system: filter elements and their selection

This is where those same people actually liveair dust purification installations. Bag filters, cartridge filters, electric precipitators - each has its own niche. Sleeves are good for large volumes and non-stick dust, cartridges are good for fine cleaning, but they are more expensive to maintain. Electrostatic precipitators are effective for certain types of aerosols, but are complex and demanding to operate.

A key parameter that is often not looked at is not just efficiency (for good filters it is already 99.9%), but resistance to abrasion and the ability to regenerate. If the dust is abrasive (like quartz), a regular needle-punched sleeve will not last long. You need fabric with a special coating or a special cartridge design. And regeneration... Pulse blowing with compressed air is standard. But the pressure, pulse duration, sequence of cleaning sections - this is adjusted for specific dust. Too little blowing - the filter quickly becomes clogged, resistance increases, and the fan is overloaded. Too strong or frequent - destroys the tissue, reduces the resource. You find the balance only experimentally, observing the pressure drop across the filter.

There was experience with filters for the magnetite concentrate grinding section. The dust is heavy and magnetic. It would seem that magnetic separators can be used. But the composition also contained non-magnetic impurities. We settled on bag filters with special synthetic fabric. It was interesting that part of the captured magnetic dust magnetized the sleeves themselves, which ultimately helped to hold the next layer. An unexpected side effect that ended up increasing the intervals between regenerations. But I had to make sure that the layer did not become too thick - otherwise the cleaning would stop working.

Equipment and implementation: from drawing to workshop

A good theory breaks down against the harsh reality of installation and operation. When designing a system, you need to imagine in advance how it will be serviced. Will there be access to the hatches to replace the hoses? Will there be dead zones where dust will accumulate? How is the unloading of collected dust from the bunker organized? I often see beautiful 3D models where everything is compact, and then you arrive at the site and realize that in order to remove the cartridge, you need to disassemble half of the installation. This is wrong.

Here, by the way, it is worth mentioning the approach of some manufacturers who have their own heavy engineering. For example,LONGI Corporation(official website -https://www.ljmagnet.ru). This is not a specific air purification profile, but their experience in creating mining equipment, such as magnetic or gravitational separation equipment, is very important. They understand what dust is on an industrial scale, how it behaves in a flow, and what loads the equipment in the workshop experiences. When such a company undertakes developmentair dust purification installations, it does not come from abstract standards, but from the physics of the process and operating conditions. Their Fushun facility, with an area of ​​140,000 m2 and a staff of engineers, is not just a production facility, but an accumulated base for working with bulk media. This means that when designing, they can take into account nuances that are purely ?ventilation? the company will not be obvious: vibrations, abrasive wear, the need for integration with other technological equipment.

When installing your system, always require contractors to observe two things: the tightness of the welded seams of the air ducts (check by crimping!) and accurate balancing of the network. If there are several aspiration points on one line, but they are configured incorrectly, the air will follow the path of least resistance, and the farthest or most “difficult” ones will follow the path of least resistance. the points will stop working. Then you will puzzle over why there is dust in one corner of the workshop, but not in the other.

Economy and security: what is the priority?

The customer always wants to save money. And often savings are made on materials: use cheaper fabric for filters, use thin metal for the housing, use a simpler fan. This is a false economy. Cheap fabric will wear out faster, the housing will rust or suffer from vibration, and a weak fan will not provide the required flow rate with the increased resistance of a clogged filter. As a result, in a year or two - a major overhaul instead of the planned replacement of consumables.

But there is another side - energy consumption. Modern installations are designed to reduce it. Frequency converters on fans that regulate performance depending on demand, pressure sensors that optimize regeneration cycles. This is no longer a luxury, but a necessity. The initial investment is higher, but it pays for itself through savings on electricity. You need to be able to convey this to those who count money.

And, of course, safety. Dust is not only a sanitary MPC standard. This is an explosive hazard. Many organic and some metal dusts form explosive mixtures. The installation must have appropriate explosion-proof versions of electric motors, pressure relief valves, and fire extinguishing systems. This is not an item on which you can cut the budget. One incident with a fire in the filter will wipe out all the savings. I always insist on a full set of automatic protective equipment, even if the customer winces. I explain with examples; fortunately, there are plenty of them in the history of the industry.

Looking to the future: what's changing?

The trend of recent years is intellectualization. Simple timers for regeneration are becoming a thing of the past. In their place are systems based on differential pressure sensors, which “understand” when the filter really needs cleaning. Remote monitoring of parameters appears: filter resistance, temperature, pressure in the pulse system. This allows you to move from planned preventive maintenance to repair based on actual condition. Greatly saves filter life and prevents sudden stops.

Another trend is hybrid solutions. Not justair dust purification installations, but a combination of methods. For example, preliminary separation of a large fraction in a cyclone or multicyclone, then fine cleaning in a bag filter. Or the use of electrostatics for pre-agglomeration of small particles before the filter. This improves the overall efficiency and life of the main filter element.

What will remain the same? The importance of proper design and understanding of technology. Even the most advanced filter will not cope if the aspiration system is designed in isolation from the real source of dust. And here you come back to experience again. To companies that grew out of industry like the sameLONGI. Their story, which began in 1993, and the path to the largest enterprise with the production of thousands of pieces of mining equipment per year is a story about a deep immersion in industrial processes. Such background is invaluable when it comes not to a box with a filter, but to a comprehensive solution to the problem of dust in the workshop. After all, in the end, it is important not to sell the installation, but to keep the workshop clean, the equipment to work without overload, and people to be in safe conditions. Everything else is tools to achieve this goal.