A unique, innovative concept for the ultimate solution of material flow problems
by Gennady Carmi, Ph.D.
CEO, Flow Industries Ltd., Israel
Flow Industries’ Silo-Flow and Turbo-Flow systems employ a technology using a new, proven concept of cyclical sudden, high-pressure air discharges (up to 3000 PSI or 200 bars) for eliminating blockages and accumulations in all types of silos, hoppers, bins and bunkers, as well as buildups in calciners, riser ducts, cyclones, feedshelves, chutes and coolers.
Limitation of existing solutions
Existing solutions of bulk material flow are usually air blasters or air cannons and Cardox. An air cannon consists of a fast-acting normally-closed valve and a pressure tank. The tank may be of various capacities and is filled with air compressed up to 100 PSI (7 bar). The cannon releases the compressed air from the pressure tank into a storage or process vessel and this discharge is supposed to break down accumulations and blockages.
In many cases, the maximum pressure amplitude of 100 psi of traditional air blasters is not sufficient to do the job effectively. To overcome the disadvantage of low power discharges, plants usually install a great number of cannons. Since bulk material has usually cracks and holes, a part of the air released by the cannon immediately escapes over the paths of the least resistance, causing immediate pressure drop and making the process even less efficient. For hard buildups like in high-temperature facilities, air cannons slightly reduce the rate of buildup formation but are very inefficient to clean them or maintain the surface clean.
Cardox is a method of converting liquid carbon dioxide into gas inside the tube containing at one end a bursting disc. Gas rapidly expanding in the tube breaks the disc and creates a blast outside the tube. The method is used mostly to clean hard buildups in high-temperature facilities and creates only a single blast per charge. The method is inconvenient and expensive while has a potential to damage the refractory.
Silo-Flow™
General.
The Silo-Flow™ patented technology has been developed and marketed worldwide by Flow Industries Ltd.Silo-Flow™ devices (SFDs) are pneumatic devices for sudden multi-pulse release of air compressed at up to 3000 psi (200 bar) into the plant storage or process vessel to meet unique application requirements.
Operation.
Silo-Flow™ system consists of SFD, a control panel (CP), one or two standard high-pressure tanks and a dedicated high-pressure compressor (Figure 1). The compressor supplies air to the high-pressure tanks, which are connected to the SFD by a high-pressure tubing through a normally closed CP valve, so that in the standby mode the SFD is not under pressure. The SFD is attached to the vessel wall by a mounting socket enabling insertion of the SFD nozzle into the vessel. The system can be activated from the control room by a standalone timer or manually by opening the CP valve and allowing the compressed air from the cylinders to flow freely into the SFD. As soon as compressed air reaches the SFD, it continuously creates powerful air pulses (blasts) with the frequency of one pulse per three or four seconds as long as the air supply is activated. Each such pulse results in a shock wave followed by a high velocity air stream. The shock wave and air stream inside the plant vessel dislodge any blockage or build-ups inside. The SFD is programmed to ‘fire’ at predetermined intervals, depending on the application. In addition, air pressure is fully controlled from as low as 300 psi (20 bar) to 3000 psi (200 bar).
Figure 1:
Typical Silo-Flow™ System Configuration
Silo-Flow™ Device working principle.
The SFD working principle is based on a unique innovative concept of continuous firing of blasts triggered by the incoming high-pressure gas. Pressure of the gas flowing into the device governs the firing power. The higher the gas pressure, the stronger the firing pulse. In general, the SFD consists of two chambers separated by a piston. When air is fed into the device, the inlet chamber is filled more quickly and has a higher pressure than the pressurized chamber. This keeps the piston in a closed (charged) position (See Figure 2A). As gas continues to fill the SFD, the pressure in the pressurized chamber increases and becomes close to that of the Inlet chamber. Because of the different piston surfaces exposed to the chambers, the piston is eventually forced towards the inlet chamber and opens the discharge ports releasing the energized compressed air stored in the pressurized chamber (See Figure 2B). This burst of air is directed into the storage or process vessel through release tunnels alongside the SFD body. When the compressed air reaches the vessel and atmospheric pressure inside, the sudden jump in pressure inside the vessel creates an instant shock wave and a strong turbulent air flow throughout the material inside.
Figure 2A:
Compressed air filling the inlet chamber (top-right) first
and more slowly filling the pressurized chamber (bottom-left).
Figure 2B:
Compressed air is released from the pressurized chamber through
the release tunnels and into the vessel, creating the shock wave and turbulent air flow.
Silo-Flow replacing natural gypsum with synthetic gypsum
The availability and low cost of synthetic gypsum (a by-product of power plant activity) has enabled cement producers to reduce the demand for mined (natural) gypsum. But synthetic gypsum is a cohesive material and has much more problematic properties than natural gypsum, causing severe flow and operational problems industrywide, regardless of the gypsum bin design or cover. These flow problems significantly impact productivity, to the extent that cement manufacturers avoid replacing natural gypsum with synthetic.
Like many other cement plants, the Lehigh plant in Alabama tried to replace natural gypsum with synthetic, but experienced severe problems with the flow of synthetic gypsum in its feeder bins although there was no problem with natural gypsum flow. Despite the installed air cannons (several per bin), the gypsum bins would severely clog with the synthetic gypsum, so the plant continued using the more expensive natural material. The plant engineers were frustrated with the continued inability to use to the synthetic gypsum. When they heard that Silo-Flow technology assured continuous and stable material flow, they decided to try it at the plant.
The plant had the device fire for 25 seconds (5 ‘shots’) every 20 min at about half its maximum power (1500 psi). After several trials with various mixtures of synthetic and natural gypsum, they moved to 100% synthetic gypsum. The SFD maintained continuous material flow of 100% synthetic gypsum at all times. The plant achieved huge savings with the move to 100% synthetic gypsum and paid back the investment in less than a year.
Turbo-Flow™
Turbo-Flow™ System working principle.
Turbo-Flow™ uses the same proven and reliable SFD mechanism with an additional feature of injecting a small quantity of water into the gas blast. Turbo-Flow™ system creates repeated high impact combined air-water spray that covers a large wall area. Once the air and water supply are switched on, the TFD pulses automatically at a rate of one pulse every 3-4 seconds. Typically, the system is activated for 30-90 seconds every 30-90 minutes. The frequency of activation and pressure depend on the severity of the buildup. Typically each pulse will consume 0.5- 1.0 liters of water and 200-300 liters of air.
The air-water spray has a dual action. The first is the sheer impact of the combined air-water mass hitting the wall at high force generated by the high pressure air stored in the TFD and its high-speed release. The secondary action is that of the water droplets “exploding” into gas with the extreme temperature inside the vessel. This additional energy is released precisely at the target zone and magnifies the impact. Both actions are less extreme than water-jets, but they are delivered repeatedly and effectively. The TFD is mounted on any existing or custom-built 6” (for TFD-6 model) or 4” (for TFD-4 model) pipe and flange. For best results, its internal pipe connects to a heavy-duty nozzle that is built into the refractory and points towards the adjacent perpendicular wall. The nozzle can be as the one used currently with low-pressure air-cannons.
Turbo-Flow to solve the kiln feed shelf buildup problems
Buzzi plant in Italy, like many other plants, experienced severe buildup problems with its preheater feed shelf. These buildups affected process efficiency, raised maintenance expenses, and caused costly process interruptions. As air cannons were known for their inability to cope with the hard buildups and Cardox introduced a potential damage to refractory and safety risks for personnel, the plant searched for an efficient and safe method to prevent such buildups, and chose Turbo-Flow system. In order to compare the systems’ efficiency, Turbo-Flow was installed on one side of the feed shelf while the air cannon was installed on the other side. Both were activated for several months. Figure 3 shows the surface of the feed shelf at the end of the trial. As one can see, the surface opposite the Turbo-Flow Device is completely clean, while the surface opposite the air cannon is covered with buildup. For a complete solution to the buildup problem, the plant installed an additional Turbo-Flow Device instead of the air cannon.
Figure 3:
The clean surface against the Turbo-Flow nozzle (1),
and buildup covering the air cannon nozzle and the surface opposite it.
A Unique, Innovative Concept for the Ultimate Solution of Material Flow Problems
A unique, innovative concept for the ultimate solution of material flow problems
by Gennady Carmi, Ph.D.
CEO, Flow Industries Ltd., Israel
Flow Industries’ Silo-Flow and Turbo-Flow systems employ a technology using a new, proven concept of cyclical sudden, high-pressure air discharges (up to 3000 PSI or 200 bars) for eliminating blockages and accumulations in all types of silos, hoppers, bins and bunkers, as well as buildups in calciners, riser ducts, cyclones, feedshelves, chutes and coolers.
Limitation of existing solutions
Existing solutions of bulk material flow are usually air blasters or air cannons and Cardox. An air cannon consists of a fast-acting normally-closed valve and a pressure tank. The tank may be of various capacities and is filled with air compressed up to 100 PSI (7 bar). The cannon releases the compressed air from the pressure tank into a storage or process vessel and this discharge is supposed to break down accumulations and blockages.
In many cases, the maximum pressure amplitude of 100 psi of traditional air blasters is not sufficient to do the job effectively. To overcome the disadvantage of low power discharges, plants usually install a great number of cannons. Since bulk material has usually cracks and holes, a part of the air released by the cannon immediately escapes over the paths of the least resistance, causing immediate pressure drop and making the process even less efficient. For hard buildups like in high-temperature facilities, air cannons slightly reduce the rate of buildup formation but are very inefficient to clean them or maintain the surface clean.
Cardox is a method of converting liquid carbon dioxide into gas inside the tube containing at one end a bursting disc. Gas rapidly expanding in the tube breaks the disc and creates a blast outside the tube. The method is used mostly to clean hard buildups in high-temperature facilities and creates only a single blast per charge. The method is inconvenient and expensive while has a potential to damage the refractory.
Silo-Flow™
General.
The Silo-Flow™ patented technology has been developed and marketed worldwide by Flow Industries Ltd. Silo-Flow™ devices (SFDs) are pneumatic devices for sudden multi-pulse release of air compressed at up to 3000 psi (200 bar) into the plant storage or process vessel to meet unique application requirements.
Operation.
Silo-Flow™ system consists of SFD, a control panel (CP), one or two standard high-pressure tanks and a dedicated high-pressure compressor (Figure 1). The compressor supplies air to the high-pressure tanks, which are connected to the SFD by a high-pressure tubing through a normally closed CP valve, so that in the standby mode the SFD is not under pressure. The SFD is attached to the vessel wall by a mounting socket enabling insertion of the SFD nozzle into the vessel. The system can be activated from the control room by a standalone timer or manually by opening the CP valve and allowing the compressed air from the cylinders to flow freely into the SFD. As soon as compressed air reaches the SFD, it continuously creates powerful air pulses (blasts) with the frequency of one pulse per three or four seconds as long as the air supply is activated. Each such pulse results in a shock wave followed by a high velocity air stream. The shock wave and air stream inside the plant vessel dislodge any blockage or build-ups inside. The SFD is programmed to ‘fire’ at predetermined intervals, depending on the application. In addition, air pressure is fully controlled from as low as 300 psi (20 bar) to 3000 psi (200 bar).
Figure 1:
Typical Silo-Flow™ System Configuration
Silo-Flow™ Device working principle.
The SFD working principle is based on a unique innovative concept of continuous firing of blasts triggered by the incoming high-pressure gas. Pressure of the gas flowing into the device governs the firing power. The higher the gas pressure, the stronger the firing pulse. In general, the SFD consists of two chambers separated by a piston. When air is fed into the device, the inlet chamber is filled more quickly and has a higher pressure than the pressurized chamber. This keeps the piston in a closed (charged) position (See Figure 2A). As gas continues to fill the SFD, the pressure in the pressurized chamber increases and becomes close to that of the Inlet chamber. Because of the different piston surfaces exposed to the chambers, the piston is eventually forced towards the inlet chamber and opens the discharge ports releasing the energized compressed air stored in the pressurized chamber (See Figure 2B). This burst of air is directed into the storage or process vessel through release tunnels alongside the SFD body. When the compressed air reaches the vessel and atmospheric pressure inside, the sudden jump in pressure inside the vessel creates an instant shock wave and a strong turbulent air flow throughout the material inside.
Figure 2A:
Compressed air filling the inlet chamber (top-right) first
and more slowly filling the pressurized chamber (bottom-left).
Figure 2B:
Compressed air is released from the pressurized chamber through
the release tunnels and into the vessel, creating the shock wave and turbulent air flow.
Silo-Flow replacing natural gypsum with synthetic gypsum
The availability and low cost of synthetic gypsum (a by-product of power plant activity) has enabled cement producers to reduce the demand for mined (natural) gypsum. But synthetic gypsum is a cohesive material and has much more problematic properties than natural gypsum, causing severe flow and operational problems industrywide, regardless of the gypsum bin design or cover. These flow problems significantly impact productivity, to the extent that cement manufacturers avoid replacing natural gypsum with synthetic.
Like many other cement plants, the Lehigh plant in Alabama tried to replace natural gypsum with synthetic, but experienced severe problems with the flow of synthetic gypsum in its feeder bins although there was no problem with natural gypsum flow. Despite the installed air cannons (several per bin), the gypsum bins would severely clog with the synthetic gypsum, so the plant continued using the more expensive natural material. The plant engineers were frustrated with the continued inability to use to the synthetic gypsum. When they heard that Silo-Flow technology assured continuous and stable material flow, they decided to try it at the plant.
The plant had the device fire for 25 seconds (5 ‘shots’) every 20 min at about half its maximum power (1500 psi). After several trials with various mixtures of synthetic and natural gypsum, they moved to 100% synthetic gypsum. The SFD maintained continuous material flow of 100% synthetic gypsum at all times. The plant achieved huge savings with the move to 100% synthetic gypsum and paid back the investment in less than a year.
Turbo-Flow™
Turbo-Flow™ System working principle.
Turbo-Flow™ uses the same proven and reliable SFD mechanism with an additional feature of injecting a small quantity of water into the gas blast. Turbo-Flow™ system creates repeated high impact combined air-water spray that covers a large wall area. Once the air and water supply are switched on, the TFD pulses automatically at a rate of one pulse every 3-4 seconds. Typically, the system is activated for 30-90 seconds every 30-90 minutes. The frequency of activation and pressure depend on the severity of the buildup. Typically each pulse will consume 0.5- 1.0 liters of water and 200-300 liters of air.
The air-water spray has a dual action. The first is the sheer impact of the combined air-water mass hitting the wall at high force generated by the high pressure air stored in the TFD and its high-speed release. The secondary action is that of the water droplets “exploding” into gas with the extreme temperature inside the vessel. This additional energy is released precisely at the target zone and magnifies the impact. Both actions are less extreme than water-jets, but they are delivered repeatedly and effectively. The TFD is mounted on any existing or custom-built 6” (for TFD-6 model) or 4” (for TFD-4 model) pipe and flange. For best results, its internal pipe connects to a heavy-duty nozzle that is built into the refractory and points towards the adjacent perpendicular wall. The nozzle can be as the one used currently with low-pressure air-cannons.
Turbo-Flow to solve the kiln feed shelf buildup problems
Buzzi plant in Italy, like many other plants, experienced severe buildup problems with its preheater feed shelf. These buildups affected process efficiency, raised maintenance expenses, and caused costly process interruptions. As air cannons were known for their inability to cope with the hard buildups and Cardox introduced a potential damage to refractory and safety risks for personnel, the plant searched for an efficient and safe method to prevent such buildups, and chose Turbo-Flow system. In order to compare the systems’ efficiency, Turbo-Flow was installed on one side of the feed shelf while the air cannon was installed on the other side. Both were activated for several months. Figure 3 shows the surface of the feed shelf at the end of the trial. As one can see, the surface opposite the Turbo-Flow Device is completely clean, while the surface opposite the air cannon is covered with buildup. For a complete solution to the buildup problem, the plant installed an additional Turbo-Flow Device instead of the air cannon.
Figure 3:
The clean surface against the Turbo-Flow nozzle (1),
and buildup covering the air cannon nozzle and the surface opposite it.
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