Nova Analytical Systems: steel heat treat

Showing posts with label steel heat treat. Show all posts

Wednesday, March 18, 2015

#208 - Tenova Core Receives Order from Bilstein Group for Bell-Type Furnaces

From industrialheating.com:

Tenova Core has been contracted by Bilstein Cold Rolled Steel LP for the design and supply of HPH (high-performance hydrogen) bell-type furnaces for installation at its facility in Bowling Green, Ky. The furnaces will be used to anneal steel strip coils in a 100% hydrogen atmosphere. The project scope includes: HPH heating hoods, annealing bases and JET cooling hoods as well as associated equipment and process-control systems.

A special high-performance recirculation system ensures effective gas circulation and superior temperature uniformity. The annealing-base design is optimized for obtaining the lowest dew point possible and can be used for annealing almost any grade of steel strip coil. It also provides many years of dependable operation while requiring minimal maintenance. JET cooling requires no cooling water and ensures homogeneous cooling of all coils.

A bell furnace is a batch-operated heat-treatment furnace in which products are heated under a movable dome. It is used for heat treatment of sheet and light-section rolled products in a controlled gaseous medium. Tenova’s HPH system uses hydrogen as the atmosphere gas and features high-convection technology. The advantages of hydrogen compared with nitrogen include lower density, higher thermal conductivity and improved reduction potential, resulting in enhanced strip cleanliness. As a result, this technology has established itself as a standard throughout the world.

Bell furnaces are classified according to use (treatment of coils of narrow strip, sheets, rods, and so on). The most common bell furnaces are the single-stack and multistack types used for annealing coils of cold-rolled steel strip. In multistack bell furnaces, three to eight stacks, each of which has its own muffle for protection against the effects of the hot air and products of combustion, are mounted on a rectangular stand under the heating dome. Each stack is 3–5 m high and contains three to five coils with a total weight of up to 180 tons.

The bell furnace dome is heated by gas or electrical resistance heaters. Upon completion of the heating process, the dome is transferred by crane to another stand and the products are left to cool under the muffles on the first stand. Heat exchange under the muffle is intensified by forced circulation of controlled gas. Cooling is accelerated by wetting the muffle with water or blowing cold air over it.

During treatment in a bell furnace the coils of strip are loose, with spaces between the coil loops so that the gas circulates between the loops and flows over the entire surface of the strip, which makes possible thermochemical treatment and acceleration of heating and cooling.

For more information, contact Tenova Core at:

Tenova Core

Cherrington Corporate Center

100 Corporate Center Drive

Coraopolis, PA 15108-3185

Phone: (412) 262-2240

Fax: (412) 262-2055
core@tenova.com

Plant photo of bell furnaces from Tenova Core.
Bell furnace diagram from Industrial Heating article The Annealing Process Revealed (Part Three: Annealing of Steel Coils) Some information from Tenova Core website and from The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

Thursday, January 23, 2014

#168 - Nova Analyzers from the Field – Episode 4

We received this beauty into our service department recently. This is a continuous H2 / CO2 analyzer that has been connected to a heat treat furnace for about 14yrs now.

As can be seen, the unit is covered inside and out with black grime. The tubing has turned yellowish-brown. The jet black bowl filters at the bottom of the picture were actually transparent when they were new. It is a small miracle that the detectors were able to function for so many years in such harsh conditions.

Some of the black grime may be soot resulting from combustion of fuel in a low O2 environment. Some furnaces are operated this way intentionally to produce a certain atmosphere around the metal products that are being heat treated. However, most of the surfaces on / in this analyzer are also quite tacky / sticky.

Some types of metal heat treating, such as sintering, employ waxes and binders as part of the manufacturing process that later burn off in the heat treat furnace. These oil vapor products can later condense onto cooler surfaces and gradually accumulate there. That may be what is coating the various surfaces of this analyzer. This coating is probably also present on the optical surfaces in the detector assembly.

Infra-red detectors need to ‘see’ through a set of glass barriers and then through a volume of the sample gas. Some vapors deposit a colored film which will eventually become opaque like the black bowl filters mentioned above. If the detector can’t see through its window, it cannot make measurements.

Even non-optical detectors are sensitive to oil vapor contamination. We see this issue in the power industry on large generators. Electric generators are sealed with oil which can be vaporized over time and be pulled into a hydrogen purity analyzer. Oil-contaminated hydrogen detectors will not function properly. So we always provide an oil vapor filter assembly with the generator atmosphere analyzers. Maybe that would have been a good investment on this analyzer from the field.

I notice that this particular analyzer has a water-cooled condenser mounted on the left side of the cabinet (not visible in this picture). The purpose of this component is to help remove water from the sample gas. The condenser is basically a tube within a tube. Cold water is filtered and flowed into one end of the outer tube, and out at the other end.

The cold water surrounds the inner tube and keeps it cool. On the inside of the inner tube, the cool tubing wall causes moisture in the sample gas to condense out. The condensed water runs down and is collected and drained in the condensate traps which mount on the bottom of the analyzer. The dried sample gas continues on into the analyzer. Of course, this whole concept only works if there is a continuous supply of cold water. In some regions, this cannot be guaranteed.

Another quirk of this analyzer is the fact that there is only a display for the H2 reading even though there is also a CO2 detector. In this application, the H2 reading was critical, but the CO2 reading was not. However, the presence of CO2 will interfere with accurate an accurate H2 reading. So we measure the CO2 and actively compensate the H2 reading. This keeps the H2 reading accurate even if the CO2 levels vary continuously.

It is hard to say what the future of this particular analyzer will be. I assumed that it was un-repairable. However, the owner wanted to try replacing the tubing and some of the other internal components. They probably also had to clean the optical surfaces in the detector as much as possible. How much longer the analyzer will stay functional, is anyone’s guess. But we are pleased to see that a Nova instrument has remained operational in adverse conditions for this long.

A new version of this equipment is still readily available. Check here in the heat treat section of our website.

Episode 1 - old portable flue gas with dual CO channel
Episode 2 - portable ppm H2 analyzer for university metallurgical lab
Episode 3 - ex-proof H2 analyzer in South Africa

If a system like this is of interest to you, contact Nova for details.

1-800-295-3771

sales at nova-gas dot com

websales at nova-gas dot com

http://www.nova-gas.com/

https://twitter.com/NOVAGAS

http://www.linkedin.com/company/nova-analytical-systems-inc-

http://www.tenovagroup.com/

Thursday, June 20, 2013

#127 - Tenova Expands Further into Heat Treatment Furnaces

Milan, April 22th 2013 – LOI Thermprocess GmbH has signed an agreement with the European Capital S.A. SICAR for the acquisition of MTH. The acquisition remains subject to usual conditions precedent including the approval by the relevant antitrust authorities.

MTH is a holding company based in Menden, Germany, and controls the companies Schmetz (Germany, established in 1945), BMI (France, 1947), Mahler (Germany, 1950), IVA/RIVA (Germany/Poland,1984) and Huisen-MTH (China, 2006).

MTH employs 321 employees working in the fields of manufacturing and service for vacuum and atmospheric furnaces for wide a range of markets (Heat Treatment Centers, Aerospace, Machine Tooling and Automotive) with a strong focus on Germany, Western Europe and Asia/China.

MTH’s product portfolio encompasses horizontal and vertical vacuum furnaces, supplied by the German company Schmetz and the French company BMI. Batch and continuous type atmospheric furnaces are covered by the two German companies IVA and Mahler. The Chinese company Huisen, with its recently extended workshop and pre-assembly workshop, near Shanghai covers the entire product range for Chinese and Asian customers.

The acquisition of the MTH and its entire portfolio of highly specialized personnel will contribute to furthering Tenova’s engineering know-how, capability and experience, especially in the field of after-sales service where MTH is a leading company.

Furthermore, the acquisition of MTH will also provide a unique opportunity for Tenova, through its subsidiary company LOI Thermprocess GmbH, to expand the furnace business in the fields of heat treatment equipment and services for parts and components. The vision is to create a worldwide furnace company covering the entire range of equipment and services for heat treatment processes in steel, automotive, aerospace and machine tool industries.