Impulse Line Blocking Diagnosis

下載 (568 KB)

Introduction

Impulse Line Blocking Diagnosis in DP Transmitters

Figure1. Connected to impulse lines

Figure 1 Connected to
impulse lines

Differential pressure (DP) flowmeters composed of an orifice plate, a DP transmitter, and other components are widely used in many applications because they are reliable and require no wet calibration. The simple design of orifice plates and modern DP transmitters make them extremely reliable. However, the impulse lines which transmit process pressure to the DP transmitter are vulnerable to blockages caused by fluid condensation, freezing, or corrosion. Impulse line blocking is a problem that must be addressed to ensure efficient operation and maintenance.

Yokogawa's EJX series DP transmitter is equipped with a silicon resonant sensor that can rapidly detect both static pressure and differential pressure. These features enable the development of a diagnostic technique which detects fluctuations in static and differential pressures. By using a digital communications network such as fieldbus, operators can determine whether an impulse line at a specific installation site has been blocked. Such information can significantly reduce maintenance workload and cost.

Expected Benefits

  • Informs operators/maintenance engineers that a blockage is forming in an impulse line before the process is disrupted.
  • Predicts when the impulse line will be blocked and suggests a corrective action, based on blockage thresholds.
  • Blockage thresholds are determined based on blocking substance, flowrate variation, and the time required for taking corrective action.

Impulse-line-blocking Diagnostic Technique

(1) Fluctuation of differential, static pressures

Table 1. Fluctuating component values in impulse lines

Table 1 Fluctuating component values in impulse lines

Fluctuating components of differential, static pressures generally decrease when an impulse line is blocked.

Fluctuating components are calculated as the square summation of the difference of differential and static pressures that are sampled at very short time intervals. The amplitudes of fluctuating components are derived from the root of the square summation. Since these components are affected by flowrate changes, they are provided as fluctuation components through flowrate compensation.

Table1 shows the value of the fluctuating components when blocking occurs on the Hi-side, Lo-side, and both sides. The values for when no blocking occurs are also shown. When both sides of impulse lines are blocked, all fluctuating components decrease. When one side of an impulse line is blocked, the corresponding fluctuating component decreases. In this case the fluctuating component of differential pressure is larger than when no blockage occurs.

(2) Blocking diagnosis using water flow test rig

Figure 2. Blocking factor F with H and L side blocking

Figure 2 Blocking factor F with H and L side blocking

Blocking factor F is determined as the correlation function between the amplitudes of fluctuating components. It approaches +1 for high side blocking and -1 for low side blocking. Figure2 shows the Blocking factor F for each blocking type.

Conclusion

Operators must receive diagnostic information before a line block leads to a malfunction. Yokogawa provides predictive diagnostics based on trend analysis of the blocking factor, which improves maintenance efficiency and reduces maintenance costs.

Note:

This diagnostic function is currently available for low viscous liquids only.

產業別

相關產品&解決方案

EJX110A

EJX-A系列的傳統安裝型差壓傳送器。

EJX115A

Differential Pressure Transmitter attached to an IFO assembly based on the EJX-A Series.

EJX118A

EJX-A系列的毛細管隔膜式差壓傳送器。

EJX120A

EJX-A系列的傳統安裝型微差壓傳送器。

 

EJX130A

EJX-A系列的傳統安裝式高靜壓差壓傳送器。

EJX210A

Flanged-mounted Differential Pressure Transmitter designed for Liquid-level applications based on the EJX-A Series.

EJX430A

EJX-A系列的傳統安裝表壓傳送器,需配定導壓配管。

EJX438A

EJX438A是EJX-A系列中的法蘭安裝型表壓傳送器。

EJX440A

EJX-A 系列傳統安裝型表壓傳送器,需配定導壓配管。

EJX510A

In-Line Mount Absolute Pressure Transmitter based on the EJX-A Series.

EJX530A

 EJX-A 系列表壓傳送器,可直接安裝於管路上。

EJX610A

High Performance In-Line Mount Absolute Pressure Transmitter based on the EJX-A Series.

EJX630A

EJA-A系列高性能表壓傳送器,可直接安裝於管路上。

EJX910A

This transmitter precisely measures differential pressure, static pressure, and process temperature; then uses these values in a high-perfomance on-board flow computer to deliver fully compensated Mass Flow.

EJX930A

Designed specifically for high static pressure applications, this transmitter precisely measures differential pressure, static pressure, and process temperature; then uses these values in a high-perfomance on-board flow computer to deliver fully compensated Mass Flow.

×

Have Questions?

Contact a Yokogawa Expert to learn how we can help you solve your challenges.

置頂