Tuesday, May 31, 2016

Accurately Weigh Process Tanks in Hot, High Vibration Areas

tank weighing
Accurately weigh process tanks
in hot, high vibration ambient
conditions.
Most load cells are designed to handle vertical force and cannot discern errors introduced from side loading and/or torque loading. In real world conditions, though, load cells see much more than vertical loading, and unfortunately, can output erroneous values. While they are excellent for static weighing situations, such as scales, load cells typically can’t handle the rigors of process vessel applications.

A case in point is a chemical manufacturer with an several, existing three cubic meter batching tanks. It was decided the tanks needed modifications to provide more accurate weighing of the individual ingredients. The existing load cells were experiencing errors due to thermal expansion of the vessel, and the resultant side loads from expansion. Additionally there was a problem with vibration in the plant. A better solution was needed, and whatever the solution would be, the customer made it clear the new weighing system must provide system accuracy in the range of ±0.1%.

load cell problems
Typical areas of concern when using load cells for weighing.
An approach to deal mechanically with the thermal cycling while using the same type of load cell was discussed. It involved several mechanical modifications that required significant and costly structural changes.

BLH KIS Sensor
BLH KIS Sensor
Another suggestion was to evaluate a unique load cell design that was particularly tolerant against thermal expansion, vibration, and high lateral forces - the BLH Nobel KIS series.  The KIS load cell offered some obvious advantages over rebuilding the tanks supports and frame, namely time and expense. Beyond the short installation time and easy modification, the KIS also offers excellent reliability and accuracy.

The customer decided to “take the easy way out” and just replace the old, error-prone load cells with
BLH Instrument
BLH Instrument
KIS load cells. Installation and start-up was very easy, taking very little time. After installation, the customer was pleasantly surprised by the high accuracy of the new KIS load cells, despite the thermal expansion of the vessel and the inherent vibration.







For more information on any process weighing application, contact:

Arjay Automation
1178 E. Cliff Road
Burnsville, MN 55337-1577
Phone (800) 761-1749
Fax (612) 861-4292

Monday, May 23, 2016

Process Control Basics: The Piping and Instrumentation Diagram (P&ID)

piping &instrumentation diagram
Sample piping &instrumentation diagram
P&ID's (piping &instrumentation diagrams), or Process and Control Flow Diagrams, 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.

Intended to provide a “picture” of all of piping including the physical branches, valves, equipment, instrumentation and interlocks. The P&ID uses a set of standard symbols representing each component of the system such as instruments, piping, motors, pumps, etc.

P&ID’s can be very detailed and are generally the primary source from where instrument and equipment lists are generated and are very handy reference for maintenance and upgrades. P&ID’s also play an important early role in safety planning through a better understanding of the operability and relationships of all components in the system.


For more information, contact:
Arjay Automation
www.arjaynet.com
1178 E. Cliff Road
Burnsville, MN 55337-1577
Phone (800) 761-1749
Fax (612) 861-4292


Tuesday, May 10, 2016

Industry Application eBooks Available from Yokogawa

Yokogawa, an internationally recognized process automation and control provider, strives for customer satisfaction through operational excellence, bringing long-term success to its customers. Now available are collections of actual cases in which Yokogawa helped leading companies in a variety of industries address specific challenges and achieve their goals. The new e-books were redesigned and subdivided into six sectors including LNG, Oil & Gas, Chemical, Pharmaceutical, and Renewable Energy.

Browse the e-books online for insight into the breadth and depth of Yokogawa's capabilities and their commitment to their customer's success. Depending on your screen size, you may need to scroll down the page to see the e-books at the link. The books can be browsed using the online reader, or downloaded as a PDF file.



Wednesday, May 4, 2016

Smart Motor Operators Make Better Sense When Replacing Old Disconnect Switches

Electrical generating substations have hundreds of aging disconnect switches. Many motor operators have reached the end of their useful life and need to be replaced. Instead of replacing them with the same 40 year old technology, engineers should consider replacing them with smart motor operators. Smart motor operators are grid friendly, much more efficient, safer, and mitigate some of the more common problems in substations, namely bounce, knocking, arc flashing, and maintaining contact pressure.

Bounce
Different makes and designs of air break disconnect switches provide their own level of bounce in their operations. From minor bouncing on high quality switches, to major bouncing on poorly designed air breaks. The problem can be so bad that entire structures oscillate causing major concerns to their users.

Knocking
There are some disconnect switches designs that do not have an efficient speed reducing mechanism and allow the isolators to knock hard into the jaw while closing, most likely several times, before moving into the contact fingers. As a result, the air break and insulators undergo undesirable vibrations and movement, and in some situations, knocking shortens the contact finger lifespan.

Electric Arcs
Large electric arcs are produced on high voltage switches during operation, injecting undesirable harmonics into the grid, tending to damage the power transformer’s solid insulation. This undesirable arc also causes early degradation of the main switch contacts causing pitting and wear.

Optimal Contact Pressure
Positioning of traditional motor operators typically use cam switches, which are very difficult to adjust, provide inadequate position precision and poor reliability. Overtime they tend to misalign, resulting in a and gradual change in closing position and causing the motor operator to stop outside the optimal closing range. This adversely effects the contact quality which causes overheating resulting in damaged the main contacts.

A better solution to traditional motor operators - the “smart” motor operator.

One manufacturer, EHT of  Boucherville, Canada, offers their IMCC Smart Motor Operator, a smart and robust motor operating mechanism for controlling and monitoring disconnect switches. It offers variable speed control, real time and condition based monitoring, alarm notification, IEC 61850/DNP3 communication, and optical positioning.

The IMCC, significantly reduces (or completely removes) bouncing. By configuring and fine-tuning the system to work with a given design, the IMCC Motor Operator neutralizes the various forces that occur during operations like compression, resistance and slack. The forces are neutralized by using smooth acceleration and deceleration along with precise position measurement.

Knocking is virtually eliminated through the IMCC’s variable speed capabilities by reducing speed before entering the jaw. Additionally, the variable speed controller reduces arcing time typically by over 50%.

With a smart design such as the IMCC, cam switches are replaced with an easy to configure, robust optical positioning system. Because of the optical controls, optimal positioning and contact pressure is assured, protecting the contact fingers from overheating, and more importantly, averting problems from the mechanism stopping in the middle of an operation due to a faulty cam alignment.


For more information, contact:
Arjay Automation
1178 E. Cliff Road
Burnsville, MN 55337-1577
Phone (800) 761-1749
Fax (612) 861-4292
www.arjaynet.com