Case study

A screening system produces sand that must be sent to ten silos, located in various locations of the plant. The Customer requested a system that an operator could use in an easy and immediate way, without using electric or pneumatic drives.

As for the material, the great criticality shown by the sand is the speed of conveying in line. The pipes have included ceramic alumina-coated bends, but if the speed of the material is excessive, there will be rapid wear of the coatings but above all it may happen that the straight pipes or even the pressure vessel can be damaged.

The conveying system chosen by Rosada ILS is a D-PVS type dense-phase pressure vessel with complete pipe emptying and air assisted conveying line (ADA). The air supply has been entrusted to a proportional valve with which it is possible to set different operating pressures, allowing to optimize the air consumption according to the chosen destination as the ten transport lines have different lengths.

For the choice of the destination, Rosada ILS produces a multi-way diverter valve with manual push cart. A linkage ensures the tightening and the tightness of the feeding mouth to the line. The pressure vessel is connected to the diverter valve by means of a hose pipe.

It is a j-pack system RV model of air dilute phase pneumatic conveying.

The powders are used for the treatment of the fumes in the duct. They are stored in a silo and discharged from it in a hopper with gravimetric micro dozer.

The injection takes place by means of j-pack with a rotary valve in a pipe of stainless steel AISI connected by low pressure fast couplings The conveying air is ensured by a centrifugal blower.

The hydrated lime is a material with low flowability and under the effect of a pressure tends to compact. Therefore the system had to be able to facilitate the flow of powder through the rotary feeder, making it aerated and avoiding as much as possible constructive obstacles: restrictions of passage, anchor points that favor the formation of bridges and more.

The environmental conditions influenced significantly the functioning. In fact the condition of the air sucked through the blower can vary along the day and along the seasons. Particularly, low temperatures would have drawn unwanted cooling within the flue duct. In addition, the humidity of the air could constitute a large aggravating the state of the hydrated lime, making more difficult the sliding little by little that the material were absorbing water.

Rosada ILS has designed a dilute phase pneumatic conveying of the type with rotary valve dimensioned to ensure adequate fluidization of the powder, so as to avoid both the load lines on the loading port and on the other the jamming in the recesses in the rotor.

The conveying air is sucked by the blower through a heating battery which guarantees a minimum temperature and reduced degree of relative humidity, essentially to ensure as far as possible a fluid dry and cold.

The transition hopper is was made with an inner chamber for venting. All edges, both external and those in the inner chamber, have been The transition hopper is was made with an inner chamber for venting. All edges, both external and those in the inner chamber, have been widely rounded. This solution allows to download the hydrated lime avoiding packing on the way down, at the same time by disposing the flow of air for the flushing of the seals of the rotor and the aeration of the powder without that this hinders the loading of the compartments of the rotor of the valve.

The rotary valve The transition hopper provides to discharge the dosed hydrated lime in an ejector exhaust collector, with an original profile of the passage section from the outlet mouth of the rotary valve junction with the line of pneumatic conveyance for the purpose of facilitating the flow input of the product.

An electro-pneumatic panel allows the j-pack be managed directly by the control room.
The design of the flow processing has also led to the definition of some of the tools necessary for the proper monitoring of the parameters of the injection. A level switch on the hopper transition indicates blockages in the rotary valve. It was chosen as a function of its ability to function even in the event hydrated lime deposits are formed on the body. While a pressure switch ensures to monitor the correct pneumatic conveying pressure.

The choice of plant design that has led to the definition of the j-pack system, for the injection of hydrated lime in a flu duct, was also made on account of suitable pressure of pneumatic conveying.

Often you make the mistake to believe that in a dilute phase pneumatic conveying the choice of pressure is only the end result of a summation of pressure losses that the conveyed fluid suffers along the line. As in the pipe does not travel only the fluid but also the material to be conveyed, in general this calculation is estimated to largely excess, both in terms of flow rate of the fluid and pressure. conveying Among other things, this also implies that the choice of the blower (or compressor) is not carried out properly.
A badly executed sizing can result in excessive costs of installation and operation. It is also likely to affect the proper pneumatic conveying of material along the pipeline.

Thanks to a deep knowledge and expertise acquired over time Rosada ILS was able to ensure the reliability of the solution.

Sucked into a filter, the starch is presented as fine dust particles, that had to be put in a big bag to be stored in a designated area. The suction with the filter collector is classified in ATEX zone 22 and therefore also the recovery system must be designed to operate with the same classification.

The proposed solution is based on a dilute phase pneumatic conveying, by means of a j-pack IV model package. The component to which the pneumatic injection has been assigned is a Venturi eductor of the type in line, supplied with compressed air controlled by flow and pressure regulators. The feeding the eductor has been assigned to a rotary airlock high pressure seal, in order to contain at most the leakage of the flushing air in countercurrent pulsed by the filter above. The rotary valve discharge the powder into a conical transition chute, equipped with some fluidization plugs more a pinch of line with adjustable flow, so as to guarantee the false air necessary in order to convey the product.

The pneumatic conveying of starch has been chosen in the dilute phase with Venturi in-line eductor, fed sideways by compressed air network, regulated as in flow and pressure. This allows the material to be conveyed flows along the pipeline and along the eductor body, without deviation, as it happens with a conventional eductor.

Such a solution has the advantage of economy of supply, installation and maintenance, also because it does not require the use of a specific unit of air production at low pressure, such as a blower or other. But to understand whether the component is the optimal solution you must also consider the capacity limits and the consumption of compressed air.

The pneumatic conveying takes place in rubber hose, transferring into a cyclone automatic filter. The inlet of the big bag is provided with inflatable seal.

An instrument panel allows the management from a remote control panel.

From the point of view of the operational flow, the injection system had to be connected to a pneumatic system installed in the area ATEX 22, therefore had to be designed and constructed with suitable characteristics. The most immediate solution would be to provide for all ATEX certified machines, then certify the entire system. In this occasion our design activity has set the goal of containing the costs of supply, while maintaining compatibility with the system requirements.

The solution came with a choice of installing a rotary valve ATEX classified, also certified as an explosion-proof component.

Once installed, the component acts as a compartment against the effects of explosion that could result from the process upstream to downstream equipment, in our case eductor, the big bag filter and pneumatic components, that in turn were selected classified ATEX.

The DNA of Rosada ILS is the design of reliable and durable solutions and not the cheapest possible. Nevertheless our research is constant, also by reason of the economic aspects of a system.

The targeted search for a strategic component of higher cost has led to some savings in terms of global supply and system maintenance.

Transfer of cement dust, coming from filters and destined to silo storage.

The project consisted of a dense phase pneumatic conveying, which doubled an existing pressure vessel. For both the machines has been reviewed engineering of the line, which stretched from the original was, so that the diameters of the pipes were increased and pipe sections, diverters and line pipes with bends and wear resistant coatings on basalt and alumina ceramic supplied. When sizing and selecting the machinery and the design philosophy, it was necessary to consider the operating temperature of the dust that the pressure vessel would receive from a feeding machine, estimated at 200° C. This aspect was critical not only against wearings, which confirmed the choice of the dense phase pneumatic conveying, at a reduced speed compared to the dilute phase systems, but also with respect to the reliability of the equipment themself over the year and for the purposes of maintenance the less onerous possible.

With regard to the pressure vessel, a tank in carbon steel too, the model F-PVS has been chosen, whose bottom is equipped with a special fluidization which is added to the grafts tangential on the cone of discharge. This makes it easier particularly the initial starting of flow of the material at high temperature in the discharge below, without using excessive pressure which would also worsen the wear resistance of the collector itself.

One of the most critical components of the system is the inlet valve, which is the machine that more suffers the transition of the material during operation. it was clear from the phase commercial it was necessary select a valve that would ensure the functioning in critical condition without the need for frequent maintenance and replacement. Especially had to guarantee the pressure seal as conveying batch cycles continued over time. To do this, on the pressure vessel a spherical dome valve Dome-RILS with high temperature inflatable seal has been installed. For this component a gasket of polymeric material for high temperature has been chosen, capable of maintaining reduced hysteresis during the repeated cycles of inflation and deflation.
The dome has been made in carbon steel, on which a chrome surface was executed, in order to contain wear and promote the opening and closing under an amount of abrasive hot and tendentially packing material.

The engineering is complemented by a local electropneumatic panel and a control panel that, by means of a field transmitter, allows the monitoring of the operating pressure.

All the stages of work have affected by the beneficial effects of a regular monitoring on the territory, including a rapid expediting and logistics that have helped improve the quality of the product without a hitch of time.
It was possible to involve the customer and encourage him to take action each time that they felt the need, optimizing the relationship between the time of manufacture and the possibility of improving the final product.