Systems and Methods for Measuring Particle Accumulation on Reactor Surfaces

Abstract

Systems and methods for monitoring a particle/fluid mixture are provided. The method can include flowing a mixture comprising charged particles and a fluid past a particle accumulation probe. The method can also include measuring electrical signals detected by the probe as some charged particles pass the probe without contacting the probe while other charged particles contact the probe. The measured electrical signals can be manipulated to provide an output. The method can also include determining from the output if the charged particles contacting the probe have, on average, a different charge than the charged particles that pass the probe without contacting the probe.

1 . A method for monitoring a particle/fluid mixture, comprising:
 flowing a mixture comprising charged particles and a fluid past a particle accumulation probe;   measuring electrical signals detected by the probe as some charged particles pass the probe without contacting the probe while other charged particles contact the probe;   manipulating the measured electrical signal to provide an output; and   determining from the output if the charged particles contacting the probe have, on average, a different charge than the charged particles that pass the probe without contacting the probe.   
     
     
         2 . The method of  claim 1 , wherein manipulating the measured electrical signal comprises using the absolute autocorrelation method on the measured electrical signal, and determining the absolute autocorrelation vector of the electrical signal. 
     
     
         3 . The method of  claim 2 , wherein the absolute autocorrelation of the electrical signal comprises an approaching curve, a leaving curve, and a curve at zero lag time. 
     
     
         4 . The method of  claim 1 , wherein the charged particles comprise catalyst particles and polymer particles, and wherein the fluid comprises one or more hydrocarbons. 
     
     
         5 . The method of  claim 1 , wherein the charged particles comprise primarily polymer particles having, on average, a negative charge and a minority of catalyst particles having, on average, a positive charge, wherein the output indicates the charged particles contacting the probe are, on average, negatively charged polymer particles, and wherein the output indicates that catalyst particles are not segregating out of the mixture in an amount sufficient to cause the formation of agglomerations. 
     
     
         6 . The method of  claim 1 , wherein the charged particles comprise primarily polymer particles having, on average, a negative charge and a minority of catalyst particles having, on average, a positive charge, wherein the output indicates the charged particles contacting the probe are, on average, positively charged catalyst particles, and wherein the output indicates that the catalyst particles are segregating out of the mixture in an amount sufficient to cause the formation of agglomerations. 
     
     
         7 . The method of  claim 1 , wherein the charged particles comprise primarily polymer particles having, on average, a positive charge and a minority of catalyst particles having, on average, a negative charge, wherein the output indicates the charged particles contacting the probe are, on average, positively charged polymer particles, and wherein the output indicates that catalyst particles are not segregating out of the mixture in an amount sufficient to cause the formation of agglomerations. 
     
     
         8 . The method of  claim 1 , wherein the charged particles comprise primarily polymer particles having, on average, a positive charge and a minority of catalyst particles having, on average, a negative charge, wherein the output indicates the charged particles contacting the probe are, on average, negatively charged catalyst particles, and wherein the output indicates that the catalyst particles are segregating out of the mixture in an amount sufficient to cause the formation of agglomerations. 
     
     
         9 . The method of  claim 1 , wherein the charged particles comprise catalyst particles, and said catalyst particles comprise one or more metallocene catalysts. 
     
     
         10 . The method of  claim 1 , wherein the flowing mixture is located within a polymerization system. 
     
     
         11 . The method of  claim 1 , wherein the flowing mixture is located within a cycle line of a gas phase polymerization reactor. 
     
     
         12 . The method of  claim 1 , wherein the particle accumulation probe is in communication with an internal volume of a polymerization reactor or a cycle line of the polymerization reactor. 
     
     
         13 . The method of  claim 1 , further comprising altering one or more process parameters if the charged particles contacting the probe have, on average, a positive charge. 
     
     
         14 . The method, further comprising introducing one or more continuity additives to the mixture if the charged particles contacting the probe have, on average, a negative charge. 
     
     
         15 . The method of  claim 1 , wherein manipulating the measured electrical signal is carried out using a processor. 
     
     
         16 . The method of  claim 1 , wherein the electrical signal is measured at a sampling frequency of about 100 Hz or more. 
     
     
         17 . A system for monitoring a particle/fluid mixture, comprising:
 a fluid conveying structure having a flow path for flowing a mixture comprising charged particles and a fluid through the fluid conveying structure;   a particle accumulation probe in communication with the flow path and adapted to detect at least one electrical signal generated as the charged particles pass the probe without contacting the probe and as the charged particles contact the probe;   an electrometer in communication with the particle accumulation probe and adapted to measure the electrical signal detected by the probe; and   a processor in communication with the electrometer, wherein the processor receives the measured electrical signal, manipulates the electrical signal, and provides an output indicating (i) whether the charged particles contacting the probe are, on average, positively charged or negatively charged and (ii) whether the charged particles passing the probe are, on average, positively charged or negatively charged.   
     
     
         18 . The system of  claim 17 , wherein the fluid conveying structure comprises a polymerization reactor or a cycle line of a polymerization reactor. 
     
     
         19 . The system of  claim 17 , wherein the fluid conveying structure comprises a gas phase polymerization reactor or a cycle line of the gas phase polymerization reactor. 
     
     
         20 . The system of  claim 17 , wherein the particle accumulation probe is configured to detect both positive and negative charges.