NISCO Fan Co. now offers gas-tight and zero leakage steam-jacketed blowers for Sulfur Recovery in Chemical Industry.

Hydrogen Sulfide H2S is a main source of sulfur. In high concentrations it can be lethal. It occurs in natural gas, oil, volcanic emissions, and some mineral springs. In oil rfining processes its presence is undesirable, and it must be removed. The Clause process is one of the methods used to remove the hydrogene sulphide, and while doing so, recover elementary sulfur.

In pactice this sulfur removal process requires a gas-tight, zero leakage, high temperature and high pressure blower for intermittent duty that must handle toxic gases and must be capable of being brought on line immediately upon demand. To do this the following features on the blower must be provided:

- Double welded casing construction;
- Steam flows between the housing walls to maintain a constant 285 F gas temperature inside the fan (because below 285 F sulfur will change from a gaseous to a solid state and will "freeze" to the blower surfaces causing damage or destruction);
- A mechanical shaft seal with heat tracing and purge by air or nitrogen;
- To assure tight tolerances between the shaft and shaft seal, the housing should be supported at the centerline, and grows concentric to the fan shaft when exposed to heat.: since this support isolates housing from the drive and mounting bases, housing thermal growth doesn't cause forces to be applied to these bases.
- To prevent the shaft from taking a permanent set when the blower is idle but still exposed to the high temperature, a turning gear is provided to keep the blower rotating at a very slow speed of 25 - 40 RPM; alternatively a VFD speed control can be used

Steam jacketed construction can also be used in other thermally critical chemical processes. As to air-tifgt and zero-emission construction, it is used in the following industries:

* Pollution Control
* Pulp and Paper Industry
* Printing and Converting
* Chemical Plants
* Power Generation
* Research and Development
* Petroleum
* Food Processing
* Paint and Ink Industries

for containment of hazardous organic and inorganic compounds in industrial process plants and other critical applications. Special construction and shaft sealing devices are available for blower service requiring zero or minimal gas leakage into and out of casing.

NISCO Fan Co. has a lot of experince with gas-tight and zero-leakage construction on fans and blowers, including: multistage lip shaft seals; Buna-N, Viton and Teflon seals; mechanical shaft seals; special fan housing gasketings; single and double carbon ring seals; hermetically sealed blowers; magnetofluidic and ferrofluidic seals; and packed stuffing boxes with barrier liquids and purgeable seals.

Specific code welding processes and special fan design features are used too - to ensure complete gas tight integrity.

Some special materials and alloys frequently used in gas tight fans, especially for service in hazardous, abrasive, corrosive and high temperature environments, include:

Corten, ASTM A36 Carbon Steel, Hastelloy, Inconel, Stainless Steels of different kinds, Titanium, Monel, Aluminum, Teflon, Rubber Lining. These materials are typical for industrial applications requiring high strength alloys and super alloys too.

NISCO Fan Co. is a world wide distributor of industrial process ans OEM fans and blowers, as well as fan components; including high pressure blowers, high temperature fans, spark resistant and explosion proof ventilators, tubeaxial and vaneaxial high pressure ventilators. NISCO also does existing fans and blowers repairs, re-build, as well as dynamical wheels balancing.