The ability to operate a reliable system requires early and continuous testing from the system level down to the components that make up the system and the ability to deal with failure and malfunction. Bulk solids silos are storage vessels with several equipment running together to ensure safe and dependable raw material storage. Silo Equipment Health Monitoring System is a condition monitoring system that detects the failures of equipment installed on storage silos. Consequently it prevents any damages or losses due to malfunctioning equipment.
Pressure Relief Valve Condition Monitoring
Pressure relief valves are mechanical valves open at a pre-set pressure level to allow air to vent from the silo during silo filling with pneumatic conveying systems. During air vent, some amount of fine dust also escapes together with air and solidifies on moving surfaces of pressure relief valve. Accumulated and solidified dust on the pressure relief valve prevents it from functioning or reduces its function and completely blocks it up over time. As it is a small equipment installed at the top of the silo, any problem regarding the pressure relief valve can not be noticed on time. Consequently if the pressure relief valve does not operate when needed, the over-pressure could easily rupture the silo or blow the filter housing off the top. If the silo is located in a designated ex-hazardous area (due to ATEX reguklations), the over-pressure encountered during silo loading could be sufficient to stimulate an explosion resulting in costly damage and loss of product. Similar to over-pressure, under-pressure (vacuum) is also imposes a danger during silo discharge. When the product in the silo is unloaded rapidly without enough venting, silo may implode and collapse like a soda can.
Pressure Relief Valve Health and Condition Monitoring System makes tests on PRV periodically and just before silo filling or discharging to ensure it is operational whenever needed. A definite amount of air pressure or vacuum is applied on the internal side of PRV. Pressure level is continuously measured and valve position is checked. If the valve does not operate at the defined pressure level, system gives alarm and prevents the silo filling or discharging. The pressure level that the valve starts to open is also another indication of valves health. If this level increases at each consequent test, this means that valve is becoming clogged in the foreseenable future.
Jet Filter (Dust Collector) Condition Monitoring
Silo top jet filter is a dedusting system used to evacuate pneumatic conveying air in bulk solid silos while keeping dust inside. The smooth operation of silo jet filter is imperative for safe and efficient silo filling. For this reason, automatic filter cleaning systems are used to keep filter elements (bag or cartridge type) clean and maintain filter efficiency. In general, this is achieved either by reverse pulse jet cleaning or mechanical shaking. Depending on application and type of handled material jet filter design and capacity changes. In some applications a dust collection fan is used to provide additional vacuum to collect dust efficiently.
Dust collector condition monitoring system collects the process data from dust collector to detect problems before happening. Differential pressure, pulse valve pressure, dust emmision and fan motor vibration are some of the important process values that show current health of the fan and possible failures before happening. Following data is collected from dedusting equipment depending on type of dust collector:
Differential pressure (also known as pressure drop) between clean and dirty air sides.
Pressure of process air supply
Pressure in pulse valve header (compressed air tank)
Pulse valve operating signals
Air flow rate
Dust collector fan motor vibration
Fan motor casing temperature
Fan motor electric current
Dust emmission at jet filter outlet
Pinch Valve Condition Monitoring
A pinch valve functions as a shut-off valve and prevents the product flow completely with the aid of proper sealing. Actuation of the valve, the pinching action is accomplished by air pressure applied on the sleeve. The flexible sleeve tightly closes the line with the help of actuation pressure. When the pinch valve is in open position, bulk material flows freely through the full bore of the valve. Since there is no change in cross sectional area through the pinch valve, pressure drop is kept minimum. In silo applications pinch valve is used to protect silo from over-pressurizing and over-filling by blocking product flow through silo filling pipeline.
Pinch valve condition monitoring system monitors the health of pinch valve by monitoring supplied pressure and it’s opening and closing action. Recorded data is used to detect any failure on the valve and provides safe silo operation.