Pneumatic conveying systems that fill silos in industrial plants generally have their own electrical controls with SCADA, DCS or similar systems. Implementing new silo equipment or several safety devices may require substantial effort. Depending on mechanical and electrical configuration of pneumatic conveying system, a local control panel handling all silo functions might be much more convenient. Polimak silo filling control system panels have the capability of connecting to DCS or SCADA units. Start, stop, level, alarm and pressure signals can easily be transmitted between both units, providing cost efficient and practical way of implementation.
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A start signal comes from plant’s main electrical control unit to inform the silo filling control system that pneumatic conveying system will start filling the silo.
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Silo control system automatically checks silo for safety.
A self test is applied on pressure relief valve, dust collector (silo top jet filter) , process air supply and silo level. If any problem is detected (high level, malfunction in pressure relief valve or jet filter), system does not allow filling, does not send confirmation signal to main electrical control unit and keeps pinch valve closed.
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If silo is not full, jet filter and pressure relief valve self tests are passed, system starts operation. and sends confirmation signal.
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Silo top jet filter (dust collector) is operated.
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Pinch valve is opened.
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Confirmation signal is sent to main electrical control unit to start filling.
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Product level in the silo is continuously measured during silo filling.
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Silo pressure is continuously measured during silo filling.
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If the pressure inside the silo rises over the limits (overpressure), silo pressure relief valve opens to decrease the silo pressure , a signal is sent to electrical panel to stop filling. Built in pressure sensor is also available for double protection if the pressure relief valve malfunctions. In this case the signal coming from pressure sensor is used to stop filling.
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Alarm signal is sent to main electrical control unit to stop filling.
After a determined time, system closes the pinch valve to protect the silo.
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If the powdered product in the silo reaches top level, system sends signal to stop pneumatic conveying. After a definite time pinch valve is closed and dust collector is stopped.
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Process values are recorded for future use
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