Applied Solutions

Catalysts are the driving force behind advancements in the chemical industry. And like many other chemical manufacturers, Dow Chemical is continuously developing new catalysts in order to improve product quality and maintain a competitive price position.

The company recently developed a reactive catalyst for use in one of its production facilities. Indications were that this new catalyst could save the company millions of euros once it reached full-scale production. The challenge was transferring the recipe using this new reactive catalyst from the laboratory to the pilot plant and, ultimately, to the production level.

Reactive catalysts are injected into a chemical process through a flowmeter. It is imperative that the precise amount of catalyst be injected into the reactor; too much or too little catalyst threatens batch quality. This crucial point is magnified when delivering a reactive catalyst because less is required to stimulate the desired chemical reaction. Hence, a highly accurate flowmeter is necessary for precise injection. Process engineers in the chemical industry prefer Coriolis meters because they measure direct mass, which delivers highly accurate and repeatable results.

Injecting a smaller amount of catalyst is not a problem at the production level because Coriolis meters are widely used at these higher flow rates. But until recently there was no Coriolis meter capable of measuring and controlling the extremely low flows necessary to test reactive catalysts in laboratory and pilot plant processes. This caused scale-up issues.

A process could be perfected on a smaller scale in the laboratory or pilot plant but lose valuable time during start-up at the production level because the flowmeter systems weren’t operating on the same principles of measurement. Process engineers spent days, even weeks, adjusting the catalyst injection process at higher flow rates.

Instrumentation experts at the Dow Terneuzen site in the Netherlands have solved this scale-up issue using the QUANTIM Coriolis mass flow controller from Brooks Instrument.

The operating range of the catalyst injection process was 1-1000 g/hr with a line size of 1/8". Due to the physical properties of the catalyst, the process was required to overcome one disadvantage. The pressure drop over the QUANTIM meter was already three bar at 100 g/hr. Dow decided to use the QUANTIM meter for the lowest part from 20-100 g/hr and use a Micro Motion CMF10 for the range from 100-200 g/hr. The QUANTIM meter double-checked the CMF at the lower flow range. Both meters were installed in series with an automatically controlled bypass and solenoid valve over the QUANTIM meter for flow rates above 100 g/hr.

In 2002, Dow built a pilot plant system with a 50-liter reactor to fully test the process. The system has been running for almost two years and the results have been excellent. Using the QUANTIM Coriolis mass flowmeter has decreased the total testing time by several months.

The first full-scale production reactor to be modified for use of the new catalyst is scheduled in the first part of 2004.

For More Information: www.emersonprocess.com/brooks/

CiDRA
Sonar-Based Meter Saves $75,000 in Pulp & Paper Application

In the pulp and paper industry, production rate is measured as outcome of the volumetric stock flow rate and consistency. The most critical production rate control point in the papermaking process is the thick stock feed to machine in order to generate optimized and stable basis weight for the produced paper or board.

The SONARtrac flowmeter by CiDRA was compared to the existing magmeter in a pulp & paper application for a four-week period. The existing magmeter on the line was spiking. Mill personnel suspected the problem was due to either entrained air or nonconductive chemical charges passing the magmeter electrodes. The nonconductive charges may have originated from chemical injection prior to the magmeter location.

The spiking magmeter, when left unfiltered, caused occasional breaks on the board machine.

When filtering was implemented to shield from the spiking, the quality of the board was negatively affected leading to "off standard" quality production. Off standard board is recycled in the process through broke handling. Since broke can be used only to replace lower quality fibers in the board basic layer, the increased broke production includes loss of expensive high-quality chemical fibers and results in increased chemical pulp consumption.

Recently, the control of this line was turned over to the SONARtrac meter. The measurement principle of the SONARtrac meter is immune to entrained air and unmixed chemicals passing through the sensing zone. The customer estimates that the SONARtrac meter will result in a savings in excess of $75,000 annually.

For More Information: www.cidra.com

Controlotron
Utility Minimizes Downtime with Low-Flow Chemical Meter

It is common for many water utilities to add fluoride to potable water for its cavity prevention benefits. However, excessive amounts of fluoride in drinking water can have serious consequences. Because of fluoride”s toxic nature, regulating agencies may require water utilities to report on the amount of fluoride added to the treated water. As a result, one water utility installed an electromagnetic flowmeter in its fluoride feed line to measure instantaneous and total flow.

After a short period of time, the utility began to experience two major problems with the magmeters. First, due to the low feed rates (170 to 390 ml/min), the magmeter required a small 0.118-inch orifice to obtain a sufficient flow velocity. This small opening was prone to clogging. As the magmeter began to clog, the meter”s accuracy decreased. Electrode fouling and eventual total clogging of the meter then caused the meter to stop operating. Maintenance time and meter downtime were excessive.

The second and more critical problem was that the magmeter”s electrodes would fail due to the corrosive nature of fluoride. This situation created two difficulties. The failed electrodes required replacement, increasing maintenance cost and downtime. Even worse, the flowmeter”s analog output would drive downscale to four mA DC. Since the meter was utilized as the primary element in a feedback control loop, the four mA DC output signal indicated that the fluoride flow rate was below the established set point. As a result, the controller”s output to the fluoride feed pump increased the pump”s stroke length to increase the amount of fluoride being added. Due to the electrode failure, the magmeter did not respond to the increased fluoride flow and ultimately caused the controller to drive the pump to full scale, creating a dangerous overfeed situation. When this situation occurred, the utility was forced to dump its four million gallon clear well.

The utility decided that the magmeter had to be replaced to minimize downtime and (more importantly) to avoid the possibility of further over-fluoride conditions. The utility began a research project to determine the best possible solution considering the difficult combination of very low flow rates and a highly corrosive liquid. The utility considered a number of different flowmeter designs in the evaluation process. Their search led them to evaluate a unique flowmeter manufactured by Controlotron, a firm primarily known for clamp-on transit-time and Doppler flowmeters. Controlotron provided a System 1020FT in-line CPVC transit-time flow tube flowmeter for evaluation. The 1020FT was designed specifically for chemical feed applications both in chemical compatibility and had the ability to handle flow rates as low as 1 GPH.

Upon installation of the 1020FT flowmeter, the utility began to measure the meter”s accuracy performance based on batch sample runs. The initial evaluation indicated an accuracy of approximately 1 percent of rate over the entire flow range. Further testing over time confirmed the meter”s performance. Additional testing was performed to evaluate the meter”s ability to avoid the two primary problems associated with the original magmeter (i.e., clogging and corrosion). The lengthy evaluation indicated that the Controlotron 1020FT did not suffer the negative effects that so adversely limited the performance of the magmeter.

The 1020FT flowmeter”s ability to handle the difficult application conditions was the result of two specific design features. First, the 3/8" bore diameter of the flow tube avoided the small restriction required by the magmeter and was therefore able to avoid the conditions that caused the clogging. Even with the large 3/8" bore, the 1020FT meter was able to provide the required accuracy at the low flow velocities. Secondly, the transducers used to make the flow measurement were non-wetted and embedded in the flow tube walls. The wetted surfaces were made entirely of CPVC that provided excellent corrosion resistance to the fluoride at operating temperature.

After completion of the evaluation process, the utility decided to replace the existing magmeter with the Controlotron System 1020FT flowmeter. Since the time of installation, the 1020FT system has maintained consistent performance within the required accuracy and without the downtime and over-fluoride conditions the utility experienced with the magmeter. As a result, the utility has installed additional 1020FT systems on polymer and alum feed lines with comparable performance.

For More Information: www.controlotron.com

Endress+Hauser
Vortex Meter Improves Efficiency of Steam Process

A Denmark-based producer of functional ingredients for the food industry and a major supplier of ingredients for nonfood applications recently implemented the Endress+Hauser Proline Prowirl 73 vortex flowmeter to help it more accurately measure its steam use. Specifically, the Proline Prowirl 73 vortex flowmeters help the company to evaluate the consumption of steam used in various applications. Energy balancing is an important task and high accuracy measurement is one of the most important steps.

The company under consideration here is producing a large variety of food ingredients out of vegetable oils and animals fats for various food products. Steam is used for a number of applications in this environment. Typically it is used for heating kettles or tanks for intermediate products. These products are either heated to a certain point or kept at a defined storage temperature depending on the nature of the application. This also applies to various production points, where the product has to be heat-traced in pipes or valves; steam is the main heat source in these cases as well.

Further, for some production operations vacuum is needed. The vacuum is created through steam injectors that work using the Venturi principle. This technology is often used for steam generation instead of a mechanical pump. Other typical points of steam use are for washdown of process equipment and sterilization.

The steam measurement with Prowirl 73 is used to study the amount of energy consumed. The measurement includes the determination of the difference between the steam entering the system and the condensate return. An Endress+Hauser electromagnetic flowmeter PROline Promag 53 is used to measure the amount of condensate recovered. Both measurements are fed back to the DCS where the energy balance is calculated. PROline Prowirl provides for that direct 4-20mA current signal with a lbs/hr value, which can be used without further calculation. Next, the efficiency of the system is determined and possible alterations are considered to improve efficiency.

The PROline Prowirl 73 was selected for this application for various reasons. The most important point was that it introduces direct mass measurement without the need of an additional thermometer and flow computer. For measurement of saturated steam, data is implemented within the instrument. Direct mass flow measurement is possible for other fluids (density information can be entered directly). Superheated steam, compressed air, water, and gas measurement are all supported.

For determining used energy, the high accuracy and reliability of the meter were also crucial selling points for this application. PROline Prowirl guarantees a measurement accuracy of better ± 1.7 percent on steam mass flow in a single unit.

For More Information: www.us.endress.com

Fluid Components International
Flare Meter Helps Achieve Regulatory Compliance

Emissions of volatile organic compounds (VOCs) at oil refineries, chemical plants, wastewater treatment facilities, landfills, and fossil-fuel electric power operations must be monitored and reported regularly to meet clean air regulations imposed by local air pollution regulating agencies such as the U.S. EPA. Failing to report or to meet standards can result in expensive fines. It also should be noted that VOCs pose a safety hazard to plant personnel and equipment, which also requires monitoring and control.

Whether a normal by-product of plant processes or as an emergency release, flare gases are typically piped into a flare system where they are burned in the open air. This process may include mixing additional fuel, air, or steam to ensure an effective blend to achieve greater than 98 percent destruction of VOCs, such as stipulated in EPA 40 CFR Section 60.18. Other regulations, such as those invoked by regional air quality management districts, often impose more stringent requirements and/or data reporting of flaring operations and events.

Selecting the right flare gas flowmeter enhances processes, helps meet safety and clean air regulatory requirements, simplifies maintenance, and reduces costs.

With an industry-first sensing element combining precision thermal mass flow and gas composition sensors, the new state-of-the-art GF03 Flowmeter from Fluid Components International delivers a superior, lowest-total-cost solution to accurate flow measurement in flaring and other variable, mixed gas composition systems.

The new GF03 Flowmeter achieves the accuracy, range, and resolution required to meet the most stringent air pollution regulations at total installed costs of up to 50 percent less than alternative technologies. It is designed specifically for flare systems, and similar variable gas applications, for regulatory emissions monitoring and reporting, continuous and event flow volume measurement, process leak detection/isolation and reduction, tributary and vent gas monitoring, loss control, material balancing, and pilot/purge gas monitoring.

Flow measurement with the GF03 Flowmeter helps improve process efficiency and plant safety, as well as reporting the gas flow rate and the totalization of gas emissions to remain compliant with all current air quality regulations. Its advanced single-sensing element, single-insertion point design provides significant cost reduction advantages in purchase price, installation labor and maintenance.

To match the capabilities of a single GF03 Flowmeter, alternative technologies such as time-of-flight Ultrasonic systems require inserting four sensors (two flow sensors plus a pressure transmitter and a temperature sensor) with precision alignment of the two flow sensors in the piping—all at a significantly higher cost. Other flow sensing technologies, such as orifice plates and Venturi tubes, do not meet today’s emission reporting regulations, are difficult to install and prone to excessive maintenance.

For More Information: www.fluidcomponents.com

KROHNE
Coriolis Meter Attracts Food & Beverage Industry

KROHNE’s single straight-tube Coriolis mass flowmeter, the OPTIMASS Series 7000, is a uniquely constructed flowmeter that offers simple installation and superior performance in density and mass flow.

The food and beverage industry benefits from this single straight-tube design because it provides the lowest possible pressure drop, and processing facilities can achieve both higher processing yields and significant reductions in operational pumping costs.

Offering a new, patented hygienic design, OPTIMASS Series 7000 meets the most stringent hygienic requirements and complies with a broad range of industry standards, including EHEDG, 3-A, and FDA.

In addition to its sanitary design, OPTIMASS Series 7000 offers self-draining capabilities and a small footprint. Due to these advantages, the flowmeter has received significant uptake in the food and beverage industry, where users are migrating away from dual or bent-tube flowmeters to single straight-tube Coriolis mass flowmeters.

For instance, a beer brewing facility is using the single straight-tube OPTIMASS to measure the exact dosing of hop extract to keep the amount used to the required minimum. Due to the very high viscosity and the subsequent need to reduce pressure drop, the brewer chose KROHNE’s OPTIMASS Series 7000 because its operating point lies in the lower range of the flow rate.

Incorporating its new, patented Adaptive Sensor Technology (AST), the OPTIMASS Series 7000 intelligently tunes itself, independent of external forces and fluid density, to produce an inherently balanced meter in even the most demanding processes. It delivers accurate metering for a wide range of flow rates, in seven different full-bore tube diameters (1/4", 3/8", 1/2", one inch, 1 ½", two inches, and three inches).

The corrosion-resistant OPTIMASS Series 7000 is the first of its kind to provide wetted parts in titanium, stainless steel, or Hastelloy, allowing it to withstand the harshest conditions. The single straight-tube design is resistant to blocking or fouling, allowing the meter to handle high viscosity fluids with ease, as well as maintain a high level of accuracy, even in the presence of entrained air.

For More Information: www.krohne.com

Magnetrol
Loop-Powered Radar Provides High Range

The Pulsar Radar transmitter by Magnetrol is based on pulse burst radar technology together with equivalent time sampling circuitry. Short bursts of 5.8 or 6.3 GHz microwave energy are emitted and subsequently reflected from the liquid level surface. Distance is calculated by the equation: D = Transit time (round-trip)/2. Liquid level is then calculated by applying the tank height value.

Application
Media: Liquids and slurries; hydrocarbons to water-based media (dielectric 1.7–100)

Vessels: Most process or storage vessels up to rated temperature and pressure. Pits and pumps as well as nonmetallic tanks such as plastic, glass-lined, and concrete.

Conditions: Virtually all level measurement and control applications including process conditions exhibiting varying specific gravity and dielectric, visible vapors, high fill/empty rates, turbulence, low to moderate foam, and buildup.

Pulsar is a top-mounted, downward-looking pulse burst radar operating at 5.8 GHz (Europe) or 6.3 GHz. Unlike true pulse devices, which transmit a single, sharp (fast rise-time) waveform of wide-band energy, Pulsar emits short bursts of 5.8 or 6.3 GHz energy and measures the transit time of the signal reflected off the liquid surface. Distance is calculated utilizing the equation distance equals the speed of light multiplied by the transit time divided by two (Distance = C x Transit Time/2), then developing the level value by factoring in tank height and sensor offset information. The exact reference point for distance and level calculations is the sensor reference point (bottom of an NPT thread, top of a BSP thread, or face of a flange). The exact level measurement is extracted from false target reflections and other background noise via the use of sophisticated signal processing.

The new Pulsar circuitry is extremely energy efficient so no duty cycling is necessary to accomplish effective measurement. For this reason Pulsar can track high rates of change (180 inches [450 cm] per minute) that were heretofore impossible with existing loop-powered radar transmitters. ETS (Equivalent Time Sampling) is used to measure the high-speed, low-power EM (electromagnetic) energy.

ETS is a critical key in the application of radar to vessel level measurement technology. The high speed EM energy (1000 ft/µs) is difficult to measure over short distances and at the resolution required in the process industry. ETS captures the EM signals in real time (nanoseconds) and reconstructs them in equivalent time (milliseconds), which is much easier to measure with today’s technology.

ETS is accomplished by scanning the vessel to collect thousands of samples. The round-trip event on a 65-foot (20 meter) tank takes only 133 nanoseconds in real time. After it is reconstructed in equivalent time it measures 200 milliseconds.

For More Information: www.magnetrol.com

Rosemount
Orifice Plate Technology Saves Plant $11,000

The Rosemount 1595 Conditioning Orifice Plate was recently introduced into the inlet water pipe that runs to the economizer (the process that uses the waste heat from the plant to produce steam) at an ammonia plant in the Midwest. Dynamic flow conditions were causing inaccurate measurement at the DP measurement point.

The three-inch diameter inlet water pipe runs approximately 20 feet above ground level for about 50 feet to the DP flowmeter. After the DP measurement point, the water feed pipe makes a 90-degree turn that extends 50 feet to the top of the economizer. The measurement point meets all DP Flow requirements; however the dynamic condition of the flow caused inaccurate measurement.

There were two potential solutions that would correct the inaccurate measurement:

1. The first solution required that an outage be scheduled so that the DP measurement point could be moved away from its current location in close proximity to the elbow. To move the DP measurement point away from the elbow would require the DP flowmeter to be removed from the system and a large section of vertical pipe run cut out. The orifice flanges would have to be removed and re-installed in the section of pipe that was removed. Next, the meter section would have to be lifted back into place and welded in. The pipe then would require an inspection and certification before the re-installation of the DP transmitter and orifice plate. The estimated cost of this solution would be $10,000 to $12,500, including labor and procurement costs.
2. The second solution was to install a 1595 Conditioning Orifice Plate. Designed for applications with limited pipe run, the 1595 Conditioning Orifice Plate only requires two pipe diameters from an upstream disturbance (double elbows, valves, and reducers), thus eliminating errors caused by upstream disturbances and downstream restrictions. This unique design achieves 0.5 percent accuracy, making it the best performing primary element. Of the three betas available (0.20, 0.40, and 0.65), 0.65 was chosen because it closely matched the original beta of 0.69 and adjusted the inches of water range. The cost for this solution was approximately $500, plus labor.

Solution number two was selected and after two months of operation the measurement was normal. The 1595 Conditioning Orifice Plate has eliminated the anomaly in the operating condition that had previously hindered measurement point. By requiring less straight-run, the company saved approximately $11,000 by reducing material costs, construction costs, and procurement costs.

For More Information: www.rosemount.com