New bag house filtration for improved emission control – an Egyptian case study: Salvatore Gallo, Boldrocchi (Italy)
Filmed at Cemtech MEA 2015, 8-11 February, Grand Hyatt Dubai, UAE
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So first of all, the first parameter, important parameter is the air to cloth ratio. It measures the velocity of the gas passing through the bag surface that we usually keep below one cubic meter per square meter. And second parameter is the can velocity, that is velocity of the gas, approaching gas from the bottom to the top approaching the free empty space among the bags.
And you can see, that can velocity parameter should be kept below 1.3 for kiln and raw mill and the clinker cooler integrated system and we have to take care to keep below one meter per second on the coal mill and bypass and cement mill. It can be, can be also varies. And the other two parameters are related to the inlet flange gas velocity to optimize distribution inside and the hopper flange velocity that it should be below the five meter per second.
Well, now we will explain how we found to improve the dust emission control and pollution control with our systems. So, we developed two key points. The first one is improving the optimization of the gas distribution inside the back filters and we will see how is possible to do it. And the second point we will see that we realised a special ventory system to optimise and say compress of their system.
So, first point we realize through the CFD simulation what the CFD simulation is the computation of through aerodynamics. So it's the process development inside distribution through 3D modelling and the assistant aided by the computer. And the three main steps, the three main stages which is for the executional, see if the simulation the first one is the three modeling design that means that we have to design in three dimensions the bag filter, the bag house casing, hopper and [xx] want to realize.
Second stage is the Iteration steps. Iteration steps means that we have to repeat and repeat the process distribution particles of gas and dusty gas inside the filters. To understand as you can see by red color, yellow coloring, velocity inside. So to take control about this distribution and then basing on the results that we got from the iteration step to apply modification architecture and modification on the filter.
This is to optimized distribution so that means that our filters are always tailor made design. So, each filter is checked by CFD simulation. Let's go in details about high dust bag filter technology. This is a picture showing our testing control room in our headquarter, Boldrocchi headquarter in Milan. You can see here that we're testing different length of specs starting from six to 12.
We have seen in the last years that many companies bag houses, company suppliers are fabricated and installing bags starting from 6-12 meters, for many reasons. For layout reasons, for dust reasons, etc., but as it's written here we can choose any length. But the importance is not the length that we use, but the importance is how much each bag works during the operation in the cycle, cleaning cycle because you can see that we can install bags 12 meter length. But if the gas is approaching part of these bags, it means that we are not using the full surface.