Thursday, April 20, 2017

Standalone Process Temperature Controllers

industrial process controllers 1/4 DIN 1/8 DIN 1/16 DIN
Industrial process controllers can be applied to temperature
or other control parameters.
Courtesy Chino
The regulation of temperature is a common operation throughout many facets of modern life. Environmental control in commercial, industrial, and institutional buildings, even residential spaces, uses the regulation of temperature as the primary measure of successful operation. There are also countless applications for the control of temperature found throughout manufacturing, processing, and research. Everywhere that temperature needs to be regulated, a device or method is needed that will control the delivery of a heating or cooling means.

For industrial process applications, the temperature control function is found in two basic forms. It can reside as an operational feature within a programmable logic controller or other centralized process control device or system. Another form is a standalone process temperature controller, with self-contained input, output, processing, and user interface. A temperature switch could be considered as a rudimentary, yet very effective standalone temperature controller. Depending upon the needs of the application, one may have an advantage over the other. The evolution of both forms, integrated and standalone, has resulted in each offering consistently greater levels of functionality.

There are two basic means of temperature control, regardless of the actual device used. Open loop control delivers a predetermined amount of output action without regard to the process condition. Its simplicity makes open loop control economical. Best applications for this type of control action are processes that are well understood and that can tolerate a potentially wide variation in temperature. A change in the process condition will not be detected, or responded to, by open loop control. The second temperature control method, and the one most employed for industrial process control, is closed loop.

Closed loop control relies on an input that represents the process condition, an algorithm or internal mechanical means to produce an output action related to the process condition, and some type of output device that delivers the output action. Closed loop controllers require less process knowledge on the part of the operator than open loop to regulate temperature. The controllers rely on the internal processing and comparison of input (process temperature) to a setpoint value. The difference between the two is the deviation or error. Generally, a greater error will produce a greater change in the output of the controller, delivering more heating or cooling to the process and driving the process temperature toward the setpoint.

The current product offering for standalone closed loop temperature controllers ranges from very simple on/off regulators to highly developed products with multiple inputs and outputs, as well as many auxiliary functions and communications. The range of product features almost assures a unit is available for every application. Evaluating the staggering range of products available and producing a good match between process requirements and product capabilities can be facilitated by reaching out to a process control products specialist. Combine your own process knowledge and experience with their product application expertise to develop effective solution options.

Thursday, April 13, 2017

Continuous On-Line Conductivity Monitoring for Water-Steam Cycle

continuous conductivity monitor for condensate, ion exchange, feedwater, steam
Continuous conductivity
monitoring system
Courtesy Swan AnalyticalInstruments
Specific conductivity measurements of water used in industrial processes can reveal important information about the water quality and its suitability for a particular use. Condensate and feedwater, as well as other process uses of water, routinely use specific conductivity measurement to confirm or analyze process performance.

Continuous conductivity measurement that delivers real time data is the most beneficial setup for monitoring water quality. The instrumentation will be an integral part of a larger control and monitoring system, so a variety of selectable output signals is advantageous. Programmable function relays that can respond when certain conditions occur provide the operator with additional automatic response options for coordinating other operations or alerting when conditions are out of a desired range.

Processing operations will benefit from products that minimize the amount of user time required to keep instrumentation in operation. Whether calibration, repair, adjustment, or required maintenance, any instrument that reduces the amount of "customer involvement" is worth considering.

The AMI CACE from Swan Analytical Instruments is a continuous on-line conductivity monitor targeted at water-steam cycle applications. It incorporates a host of technological and user friendly features that make it an advantageous choice for feedwater and condensate monitoring. Detail is provided by the datasheet included below. Share all your analytical and steam system monitoring requirements and challenges with instrumentation specialists. The combination of your own process knowledge and experience with their product application expertise will yield an effective solution.


Tuesday, April 4, 2017

Gas Density Meter Provides Continuous Inline Density Monitoring

gas density meter product configurations
Gas Density Meters
Courtesy Thermo Scientific
Gas density measurement is crucial when looking at the molecular makeup of a sample, when quantifying variables which make up a whole. Custody transfer operations and other fiscally related operations can also require gas density measurement to properly determine delivered gas quantities. The Thermo Fisher Sarasota gas density instruments are specifically designed to deliver high accuracy continuous inline measurement of density and density related variables. Employed in large scale processing, gas density measurement is often found in the gas, chemical, and petrochemical industries, along with power generation operations.

Thermo Scientific’s Sarasota line of gas density instruments provide a measurement that can, with the use of auxiliary flow computers or other electronics from the company or third party vendors, provide additional data for specific gravity, calorific value, or molecular weight. Three basic meter styles provide for direct insertion, bypass, or pocket mounting arrangements. Two versions of each type are offered, with the first providing a frequency output and 4-wire PT 100 temperature sensor output for use by a flow converter or other computational device. The second version has an onboard HART compliant density converter with 4-20 mA output.

As the measured gas flows through the meter, it interferes with the base frequency of the vibrating sensor tube in proportion to the density of the gas. The instrument measures the change in vibration frequency, which is used to calculate the density. The onboard precision RTD provides for temperature compensation. Other features include:
  • Readings unaffected by pressure
  • Available for use in hazardous environments
  • Third party certifications
  • Connection options
  • Wide temperature range operation
  • Interfaces with Thermo Fisher flow computers, or other brands
  • Continuous online density monitoring
There are numerous industrial applications for the density meters, including energy management, flue gas analysis, custody transfer, burner control, stack emissions analysis, process and quality control, and more. A specialized retractor enables removal of the direct insertion gas density meter from the piping system under operating conditions up to 2500 psi.

Variants of the instrument accommodate a wide range of application and installation requirements. More detail is provided in the datasheet included below. Share your gas density and other process measurement requirements and challenges with product application experts. The combination of your process knowledge and their product application expertise will produce effective solutions.