Tuesday, December 30, 2014

Heat Exchangers for Liquid-Gas Vaporization

Tube bundle for heating
Tube bundle for heat transfer.
Hydrocarbon and non-hydrocarbon based gases can be more efficiently stored and transported in a liquified state, providing higher media density and corresponding product weight per container. Upon reaching their final destination, the liquid can be reheated, returning to a gaseous state for distribution and use. Typical liquified gases include natural gas, oxygen, butane, propane, and nitrogen.

There are several ways to affect the physical change from liquid to gas, and picking the best option is dependent on criteria such as; 1) available energy sources; 2) plant location; 3) climate conditions; and 4) plant infrastructure.

The change from liquid to gas phase usually requires one or more vessels properly sized and designed to accommodate the vastly increased volume of the evaported liquid, handle the storage or distribution pressure of the gas, and be compatible with the process media. In most plants today, the gradual process of warming the liquified gases is done with steam-heated or oil-heated "heat exchangers" or "tube bundles".

Some heat exchanger systems may, instead of steam, use steam-heated intermediary fluids such as oil, water, or glycol-water solution to provide a smoother rate of heat transfer to the evaporating liquid. This method can employ two heat exchangers, one transferring heat from steam to the intermediary fluid, then another to transfer heat from the intermediary fluid to the liquified gaseous product to evaporate it.

Steam heated, closed-loop circulation systems play an important role in providing an efficient, low-cost and compact method to accommodate liquid vaporization. Steam is available in many industrial plants, providing a comparatively inexpensive and readily available source of heat energy. Heat exchangers are available in a range of pre-engineered capacities and forms, but it is quite common for these components to be custom fabricated to meet very specific requirements. Engineers can design their own systems from the component level, or provide performance requirements to the manufacturer and have a skid mounted unit produced, ready for connection to electric power (for control systems), energy source (steam, oil or water) and process inlet and outlet lines.

These systems can be quite technical, with numerous design considerations. The path to maximized safety and efficiency includes consultation with a heat exchanger expert as part of specification and design process. A combination of your high level process knowledge and their product and application expertise will yield the best outcome.

Wednesday, December 24, 2014

Happy Holidays and Happy New Year from Mountain States Engineering and Controls

Happy Holidays from MSEC
We at Mountain States Engineering and Controls believe the magic of the holidays never really ends, and the most important gifts we share are family and friends. Thank you for a wonderful 2014 and we wish you peace, love, and prosperity in the upcoming year.

Tuesday, December 23, 2014

High Performance Butterfly Valve Exploded View

Here is a short video that quickly displays the components of a high performance butterfly valve. High performance butterfly valves are used in the oil and gas, commercial HVAC, chemical processing, mining, pharmaceutical, water & wastewater industries. High performance butterfly valves come in wafer and lug bodies, have bodies made of carbon steel, stainless steel, or other alloys, and work under higher pressures and temperatures than "rubber lined" butterfly valves.

Wednesday, December 10, 2014

Improving Maintenance and Reliability of Bubbler Systems

According to Wikipedia "an air bubbler system uses a tube with an opening below the surface of the liquid level. A fixed flow of air is passed through the tube. Pressure in the tube is proportional to the depth (and density) of the liquid over the outlet of the tube."

A common problem with many bubbler systems used in water and wastewater systems is long term accuracy and reliability issues. The need for scheduled maintenance is required because of the possibility of  tampering, failed solenoids, changing air flow rates, or clogged downpipes due to crystal formation - particularly in wastewater applications with high entrapped solids.

A better approach is to use a level transmitter for purge control. This solution offers a highly engineered single component that is easily retrofitted to bubbler installations. These purge transmitters automatically maintain an extremely low flow continuous purge (less than 0.02 scfm) regardless of liquid depth, and minimizing formations of crystals in the downpipe. The lag time during dynamic level changes is also eliminated. Furthermore, bubbler operation is tamperproof because there is no external regulator or needle valve (or rotameter) – internally a fixed differential is maintained over a precision flow orifice.

Transmitter purge (or bubbler) technology works reliably in the presence of vapors, and, unlike ultrasonics, can be used in media temperatures of more than 350°F. Bubblers are normally used in applications where foam, solid debris, sewage sludge, or turbulence make ultrasonic, radar, or float switch devices ineffective. The purge transmitter is relative compact in size and allows for installations in tanks where other systems won’t fit.

The purge control transmitters require a compressed air supply (35-150 psig/2.4-10.3 bar) and provide a two-wire 4-20mA output that can be transmitted over substantial distances. The transmitter can be mounted directly outdoors or within small enclosed spaces at the measuring point or up to a hundred feet away.

More information on the purge transmitter may be download here.