Showing posts with label process control. Show all posts
Showing posts with label process control. Show all posts

Problems with Measuring Level of High Density Pulp Stock

Level Measurement in Pulp Stock
Level Measurement in Pulp Stock has posed problems for a wide range of level measurement technologies. In most pulp mills this is the most challenging application on site.

The environment in the high-density pulp tank is very corrosive to most common metals and the clouds of dense steam vapors that rise from the stock and foaming surface of the level are a constant source of signal loss for many non-contact technologies.

Due to the size of the vessel and density of the stock, mechanical devices are typically short  lived.Stock coatings that form on all interior surfaces add additional mechanical stress and the pulp coating deposits can adversely affect accurate level measurement performance.

One of the challenges of a level measurement device is to control the level in the stock tank, thereby helping to control the average pulp density by controlling the speed of the pump.The response time of the level measurement system is critical in controlling the pump speed and reducing pump oscillations and surges that will eventually reduce the life of the pump.Too slow of a response from the level instrument will allow the level to rise above it ’s optimum density level and cause excessive loading and wear on the pump.

Piping Specialties, Inc.
PSI Controls

The Azbil AX Series of Vortex Inline Flow Meters

Azbil AX Series
The AX Series of Vortex inline flowmeters measure flows of liquid, gas, and steam by measuring the rate at which vortices are alternately shed from a bluff body; this rate has been shown to be directly proportional to the flow velocity.

As flow passes a bluff body in the stream, vortices create pressure differentials which are measured by a piezoelectric crystal sensor, which converts these pulses into electrical signals. The meter uses an all-welded sensor design to create a strong unit and minimize potential leakage.

The Azbil AX Series can be configured to measure anything from simple volumetric flow of liquids and saturated steam up through multivariable measurements, including mass flow rate, pressure, temperature and density of liquids and steam.

Insertion style vortex meters measure fl ow by detecting the local velocity at a strategically located position within the pipe. Using local velocity, calculated by measuring the rate at which vortices are alternately shed from a bluff body within the sensor, the Azbil AX2300 uses parameters such as fluid type, pipe size, and Reynolds number to calculate accurate measurements.

Download the Azbil AX Series Vortex Flow Meter brochure here.

Piping Specialties / PSI Controls: New England's Preferred Source for Industrial Valves, Valve Automation, and Process Instrumentation

Founded in 1975, with offices in Portland, Maine and Danvers, Massachusetts, PSI has earned their reputation as New England's premier supplier of industrial valves, valve automation, process instrumentation and specialty process equipment.

PSI specializes in engineered products for these industries:

  • Power Generation
  • Pulp & Paper
  • LNG / LPG / Natural Gas / Gas Storage & Distribution
  • Pharmaceutical / BioTech
  • Food and Beverage
  • HVAC
  • Water & Wastewater

Piping Specialties, Inc / PSI Controls

What is a Piping and Instrumentation Diagram (P&ID)?

Piping and  instrumentation diagrams (P&ID's) are schematic representations of a process control system and used to illustrate the piping system, process flow, installed equipment, and process instrumentation and functional relationships therein. They are also known as "process and control flow diagrams".

They are intended to provide a “picture” of all the process piping, including the physical branches, valves, equipment, instrumentation and interlocks. By using a standard set of internationally recognized symbols, each component of the process system - instruments, piping, motors, pumps - is recognized on paper or computer screen.

P&ID’s may be very detailed and are generally the primary source from where instrument and equipment lists are generated. They are also used as a handy reference for maintenance planning and system upgrades. Furthermore, P&ID’s also play an important early role in plant safety planning by providing a thorough understanding of the operability and relationships of all components in the system.

Watch the short video below for more information.

For more information contact:
Piping Specialties / PSI

Don't Overlook the Importance of Scheduled Calibration for Your Plant's Process Instrumentation

Calibration Process Instrumentation
Calibration is an essential part of keeping process measurement instrumentation delivering reliable and actionable information. All instruments utilized in process control are dependent on variables which translate from input to output. Calibration ensures the instrument is properly detecting and processing the input so that the output accurately represents a process condition. Typically, calibration involves the technician simulating an environmental condition and applying it to the measurement instrument. An input with a known quantity is introduced to the instrument, at which point the technician observes how the instrument responds, comparing instrument output to the known input signal.

Even if instruments are designed to withstand harsh physical conditions and last for long periods of time, routine calibration as defined by manufacturer, industry, and operator standards is necessary to periodically validate measurement performance. Information provided by measurement instruments is used for process control and decision making, so a difference between an instruments output signal and the actual process condition can impact process output or facility overall performance and safety.

Calibration Process InstrumentationIn all cases, the operation of a measurement instrument should be referenced, or traceable, to a universally recognized and verified measurement standard. Maintaining the reference path between a field instrument and a recognized physical standard requires careful attention to detail and uncompromising adherence to procedure.

Instrument ranging is where a certain range of simulated input conditions are applied to an instrument and verifying that the relationship between input and output stays within a specified tolerance across the entire range of input values. Calibration and ranging differ in that calibration focuses more on whether or not the instrument is sensing the input variable accurately, whereas ranging focuses more on the instruments input and output. The difference is important to note because re-ranging and re-calibration are distinct procedures.

In order to calibrate an instrument correctly, a reference point is necessary. In some cases, the reference point can be produced by a portable instrument, allowing in-place calibration of a transmitter or sensor. In other cases, precisely manufactured or engineered standards exist that can be used for bench calibration. Documentation of each operation, verifying that proper procedure was followed and calibration values recorded, should be maintained on file for inspection.

As measurement instruments age, they are more susceptible to declination in stability. Any time maintenance is performed, calibration should be a required step since the calibration parameters are sourced from pre-set calibration data which allows for all the instruments in a system to function as a process control unit.

Typical calibration timetables vary depending on specifics related to equipment and use. Generally, calibration is performed at predetermined time intervals, with notable changes in instrument performance also being a reliable indicator for when an instrument may need a tune-up. A typical type of recalibration regarding the use of analog and smart instruments is the zero and span adjustment, where the zero and span values define the instruments specific range. Accuracy at specific input value points may also be included, if deemed significant.

The management of calibration and maintenance operations for process measurement instrumentation is a significant factor in facility and process operation. It can be performed with properly trained and equipped in-house personnel, or with the engagement of subcontractors. Calibration operations can be a significant cost center, with benefits accruing from increases in efficiency gained through the use of better calibration instrumentation that reduces task time.

Understanding How Control Valves Work

Control valveUnderstanding industrial control valve design and operation is very important if you work as a process engineer, a plant maintenance person, or if you design process control loops.

Control valves are used extensively in power plants, pulp and paper mills, chemical manufacturing, petro-chemical processing, HVAC and steam distribution systems.

There are many types, manufacturers, body styles, and specialized features, but the they all share some basics operating principles. The video below explains components, operation, and fundamentals.

Piping Specialties / PSI Controls

Instructional Video: Inserting K-Patents Generation 2.1 SAFE-DRIVE™ Process Refractometer PR-23-SD

This video is intended for individuals installing, commissioning, operating, and/ or servicing the K-Patents Safe-DriveTM Process Refractometer PR-23-SD, generation 2 model. The purpose of this video is to provide a quick guide for the above mentioned tasks in the form of K-Patents recommended best practices.

K-Patents SAFE-DRIVE™ design allows for safe and easy insertion and retraction of the sensor under full operating pressure without having to shut down the process.

Below the video is the document "Best Practices for the Safe-DriveTM Process Refractometer PR-23-SD Generation 2" for your convenience.

For more information, visit or call 800-223-1468.



Welcome to the PSI Controls and Piping Specialties Blog

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PSI Team