This section was edited by Executive Editor Harry Hutchinson.
| FLUID HANDLING & FLUID POWER |
WIRELESS MONITORING OF WATER USAGE
A pharmaceutical plant in Ireland is using Emerson Process Management’s Smart Wireless technology to keep track of the water it uses. By going wireless, we’re told, the company saved money on installation costs, and it has the option of expanding its network in the future at reasonable cost.
The plant, operated in Cork by GlaxoSmithKline, produces active ingredients that are used in the formulation of prescription drugs.
The Cork plant found that its water storage facility was too small, so it added two new storage tanks along with a new pipework infrastructure.
According to Emmett Martin, GlaxoSmithKline’s site services and automation manager, “Water is a considerable overhead to the plant so it is important that we monitor flow rates to manage consumption, and to help identify any usage trends.”
Wireless technology monitors GlaxoSmithKline’s water usage.
The tanks are about 300 meters from the main control room and there was no instrumentation or cabling in place. A wired installation would have required the addition of power and data cables buried in trenches.
The company avoided the acquisition and installation costs of cables by opting to try Rosemount wireless flow and pressure transmitters on the new storage tanks. According to Emerson, wireless communication lets a plant create a network and inexpensively add process instrumentation.
GlaxoSmithKline installed ten Smart Wireless devices: six Rosemount pressure transmitters, two Rosemount flow transmitters, and two Rosemount level transmitters. The Smart Wireless technology integrates with the plant’s automation equipment. Flow data is transmitted every 30 seconds and pressure and level data every 300 seconds to a Smart Wireless Gateway positioned on the control room roof.
The Gateway is connected using a serial connection to the DeltaV digital automation system that controls the plant utilities. From here the flow and pressure measurements are sent to a data historian and are available to plant operators for regular monitoring and reporting.
GlaxoSmithKline said it is able to identify water usage for different areas of the plant and has improved its understanding of the costs. The company said the information puts it in a position to consider changes.
POLYMER PIPING AIMS FOR GREATER SEA DEPTHS
Two British companies—Victrex Polymer Solutions and Magma Global Ltd.—are cooperating to develop technology designed to support increasingly deep subsea oil and gas extraction.
Magma Global introduced at the Offshore Technology Conference in Houston earlier this year a trademarked product called m-pipe, which is intended for risers, flow-lines, and jumpers in very-high-pressure and extreme-temperature environments. Victrex Polymer Solutions, a division of Victrex plc, supplies Magma Global with a proprietary PEEK polymer formulation that is the key ingredient of m-pipe.
Magma Global describes m-pipe as carbon polymer pipe that offers improved reliability, increased performance, lighter weight, and longer life than conventional unbonded flexible pipe or steel alternatives. Magma Global is marketing m-pipe as a solution to meet the challenges faced in harsh environments where existing technologies are reaching their limits, particularly in very deepwater applications.
According to Magma Global, m-pipe’s weight in water is one-tenth that of steel risers and withstands operational temperatures to 390 °F with no effect on corrosion or fatigue performance. The company said it is currently designing m-pipe to operational pressures of 20,000 psi. Surface roughness averages 0.05 µm.
The product is available with internal diameters of 2 to 24 inches. M-pipe with internal diameters up to 15 inches can be spooled.
Magma said it has carried out a wide range of structural tests including four point bend, tension, compression, creep, collapse, burst, inter laminar sheer strength, compression ring, stress cycling, and impact.
Magma told us that, for qualification of m-pipe, the company has chosen the risk-based approach advocated in Det Norske Veritas RP-A203 Qualification Procedures for New Technology, with independent assurance from Lloyd’s Register as the basis for qualification of its risers, jumpers, and spools. In addition Magma said it has made detailed reference to DNV-RP-F202, DNV-RP-F204, DNV-OS-F101, DNV-OS-C501 and DNV-OS-F201 to ensure it has fully captured industry best practice for these products.
The two companies are based in England, Victrex in Thornton Cleveleys and Magma in Portsmouth.
MIXER SEAL GETS MAJOR MAKEOVER
By Vic Lundberg
Sealing the agitator shaft entry point in a tank used for high temperature mixing of titanium tetrachloride (TiCl4) at its Henderson, Nev., plant was a crucial worker-safety issue for Titanium Metals Corp. (Timet). TiCl4 is an aggressive chemical that has a tendency to flash off to form a potentially noxious vapor and toxic white cloud. In addition, when the chemical comes into contact with water, it can become hazardous.
In late 2010, Timet sought out the engineering team at Quadna to advise the best way to seal the mixer shaft entry point. We faced two major challenges in developing an effective solution.
John Crane dry-running split seal.
The first was to determine how to maintain a strong positive seal. The seal design was of paramount importance and there were critical metallurgy issues as well. Previously, the system employed a double mechanical seal with a mineral-oil barrier fluid that provided lubrication between the inboard and outboard faces.
Timet wanted to use a split mechanical seal instead—because its installation and eventual replacement takes far less time. However, to enhance the operation, a dry seal was needed.
The problem? At the time, no manufacturer was producing a dry-running split seal.
The second obstacle was the length of the shaft. The mixing operation uses a long unsupported shaft, where it is common to experience excessive shaft run-out at the mechanical seal.
We recommended installing a sleeve bearing made of DuPont Vespel CR6100 polyimide. The additional sleeve would help the long shaft run true and minimize shaft run-out at the mechanical seal.
The typical clearance for a steady bearing for a shaft of the diameter used for this mixer (3 to 5 inches) is 0.020 in. of total clearance. The Vespel sleeve bearing was machined for a total clearance of 0.007– 0.010 in. The reduction in clearance between the bearing and shaft allowed the Vespel sleeve bearing to act as a primary seal as well as to keep shaft run-out well below maximum acceptable levels.
The reduction in clearance was possible because of the unique coefficient-of-thermal-expansion properties of Vespel. Thermal growth is largely confined to the z direction (along the shaft)—growth in the x and the y directions is extremely small. In addition, the material is chemically inert to TiCl4 and can operate without lubrication because of its very low coefficient of friction.
Quadna redesigned the mixer stuffing box for a John Crane Type 3740D cartridge split seal using the Vespel sleeve bearing. This represented one of the first John Crane dry-running beta split seal installations.
During final assembly of the bearing and split-seal system, a slight dimensional issue prevented installation of the John Crane seal. Because time was running short, the mixer had to be placed back into service. During subsequent operation the Vespel sleeve bearing alone sealed nearly 100 percent of the vapor and also demonstrated its effectiveness in reducing run-out. So, Quadna and plant officials decided to continue operating the unit without the seal while the minor dimensional issue was addressed. Then, at the first opportunity, we put in the dry-running seal to ensure complete containment of vapor. The split seal took only hours to install during a brief outage (versus the days required for a double seal) and has operated without a hitch.
Several vessels in the plant that were experiencing similar problems now have received John Crane Type 3740D dry-running split seals as well as Dupont Vespel 6100 sleeve bearings for their mixer shafts, resulting in the containment of all TiCl4 vapor.
These enhancements have provided other benefits, too. Significant savings come from eliminating the mineral-oil barrier fluid and specialized seal-support equipment to regulate flow and pressure required by double mechanical seals. In addition, seal replacement in the future will take much less time.
Quadna team members are incorporating all the modifications as standard offerings for new mixers that Timet is purchasing for the plant. Installation of these mixers should be completed by the end of 2011.
Vic Lundberg is a process engineer for Quadna, a DXP company.
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