Tuesday, July 25, 2017

Fieldbus Equipped Instrumentation - Part Two

Since automatic control decisions in FOUNDATION fieldbus are implemented and executed at the field instrument level, the reliance on digital signals (as opposed to analog) allows for a streamlined configuration of direct control system ports. If the central control device were to become overloaded for any reason, tasks related to control decisions could still be implemented by operators in the field. This decentralization of the system places less burden and emphasis on the overall central control unit, to the point where, theoretically, the central control unit could stop functioning and the instrumentation would continue performing process tasks thanks to the increased autonomy. Allowing for the instrumentation to function at such an increased level of operation provides a proverbial safety net for any system related issues, with the capacity for independent functionality serving as both a precaution and an example for how process technology continues to evolve from analog solutions to fully end to end digital instrumentation.

Even in terms of the FOUNDATION instrumentation itself, there were two levels of networks being developed at this increased level of operation, initially: the first, H1, was considered low speed, while H2 was considered high speed. As the design process unfolded, existing Ethernet technology was discovered to fulfill the needs of the high speed framework, meaning the H2 development was stopped since the existing technology would allow for the H1 network to perform to the desired standards. The physical layer of the H1 constitutes, typically, a two-wire twisted pair ungrounded network cable, a 100 ohm (typical) characteristic impedance, DC power being conveyed over the same two wires as digital data, at least a 31.25 kbps data rate, differential voltage signaling with a defined threshold for both maximum and minimum peak receive rates, and Manchester encoding. Optical fiber can be used on some installations in lieu of the twisted pair cable.

Most of these specifications were exactly designed to withstand extremely challenging process control environments while still not abandoning the philosophy of being easy to build and implement, especially in terms of new system establishment. The most crucial aspects of many process control systems are streamlined together, allowing for consistent communication and synchronization. All aspects are viewable from both the legacy central controller and also via each individual device. Despite the data rate of 31.25 kbps being relatively slow, what is sacrificed in terms of speed is more than made up for in terms of the system being compatible with imperfect cables and other hiccups which may destabilize a network with faster speeds. The evolved technology, ease of installation, and durability have made the H1 network a widely used implementation of the FOUNDATION fieldbus technology. Fieldbus is currently considered one of a few widely adopted industrial process control communications protocols.

For more information contact Flow-Tech in Maryland at 410-666-3200; in Virginia at 804-752-3450, or visit http://www.flowtechonline.com.

Saturday, July 22, 2017

Fieldbus Equipped Instrumentation - Part One

Autonomous control and digital instrumentation are two capabilities enabling highly precise or complex execution of process control functions. FOUNDATION fieldbus instrumentation elevates the level of control afforded to digital field instrumentation where, instead of only communicating with each other, instruments involved in particular process control systems can independently facilitate algorithms typically reserved for instruments solely dedicated to controlling other instruments. Fieldbus capable instrumentation has become the standard instrumentation for many process industry installations due to the fact the FOUNDATION design principle streamlines process systems. A large contributor to FOUNDATION's success has been faster installation as opposed to operational controllers which do not feature the fieldbus configuration. Newer process companies, or process control professionals seeking to establish a new system, have gravitated towards fieldbus due to the combined advantages of system conciseness and ease of implementation.

In a typical digital control system, dedicated controllers communicate with field instrumentation (the HART protocol is a prime example of digital communication at work in the industry). The host system controls configuration of instruments and serves as a central hub where all relevant control decisions are made from a single dedicated controller. Typically, these networks connect controllers and field devices through coupling devices and other buses which streamline many different instruments into a complete system.

FOUNDATION fieldbus approaches the same network scheme with an important difference. Whereas in a legacy or more conventional system, either algorithmic or manual decisions would need to be implemented via the dedicated system level controllers, instruments utilizing FOUNDATION fieldbus architecture can execute control algorithms at the local device level. The dedicated controller hub is still present, so that operators can view and monitor the entire network concurrently and make status changes. Algorithmic execution of control functions becomes entirely device reliant thanks to the FOUNDATION protocol. Additionally, even though FOUNDATION implements an advanced configuration, some operators use the capabilities introduced in the fieldbus upgrade to implement specific algorithms via each device while concurrently maintaining algorithms in the central controller. This dual algorithmic configuration allows for several advantages, including the ability for increased system precision.

Since individual devices in the control process are calibrated and able to execute their own control functions, issues in the process with particular devices can be isolated and dealt with in a more specified manner by technicians using the instruments in the field. The central operator retains the capacity to use the control hub to alter and direct the control system.

For more information contact Flow-Tech in Maryland at 410-666-3200; in Virginia at 804-752-3450, or visit http://www.flowtechonline.com.

Watch for Part Two of this series to be posted soon.

Saturday, July 15, 2017

Solving Critical Process Applications for the Water and Wastewater Industry

Thermal Dispersion and Coriolis technology
From the early 1960s, Fluid Components International recognized the need for flow and level instrumentation which met specific customer requirements and demands for the Water and Wastewater Industry. By utilizing Thermal Dispersion and Coriolis technology exclusively in all FCI flow, level, interface, temperature switches and mass flow meters, our products solve typical Water and Wastewater Industry application challenges with standard product features such as:
  • No moving parts
  • All welded materials of construction 
  • Direct mass flow measurement
  • No pressure drop
  • Explosion-proof design
  • Wide flow range
  • Low flow capability
The document below outlines where and how Thermal Dispersion and Coriolis technology are used throughout water treatment facilities around the USA.

For more information on any water treatment process application, contact Flow-Tech at 410-666-3200 in Maryland, or 804-752-3450 in Virginia, or visit http://www.flowtechonline.com.

Sunday, July 9, 2017

The Yokogawa TDLS8000 Tunable Diode Laser Spectrometer

TDLS8000
The Yokogawa TDLS8000
The Yokogawa TDLS8000 can quickly make in-situ measurements of gas concentrations in combustion and heating processes that are employed in the oil, petrochemical, electric power, iron and steel, and other industries.

Companies are always looking for ways to optimize processes by saving energy, reducing CO2 emissions, and improving safety and one way to do this is by optimizing the air-fuel ratio in the combustion process. To accomplish this, sensors are needed that can continuously monitor the concentration of O2 and CO+CH4 in the radiant section of fired heaters.

Product Features

  1. Highly reliable measurement - The TDLS8000's laser module includes a newly developed reference cell board that improves the reliability of absorption peak detection, which is an important step in the spectral area method. In addition, the receiving unit employs a new auto gain function that can automatically optimize detection sensitivity depending on the measurement object. By increasing the signal-to-noise ratio (S/N ratio), this improves the reliability of measurements taken in coal combustion and other processes where there is high particulate loading. Designed to meet the requirements for SIL2 certification (certification pending) defined by the International Electrotechnical Commission (IEC), the TDLS8000 will play a key support role in ensuring the safe operation of plants.
  2. Improved operability and maintenance efficiency - The TDLS8000 comes with a large 7.5-inch LCD touch screen that can display a greater variety of data. The touch screen replaces the push button interface used with preceding models, making the setting of parameters easier and more intuitive. The light source module containing the laser diode is fully sealed and damage resistant. To facilitate troubleshooting and reduce downtime, this module is able to store up to 50 days' worth of raw data that can be accessed anywhere in the world by, for example, a Yokogawa response center.
  3. Compact size - The redesigned TDLS8000 is just three-quarters the size and weight of the preceding model, allowing it to be installed in a greater variety of locations.