Nova Analytical Systems: sample conditioning

Wednesday, May 29, 2013

#124 - Particulate Removal from Sample Gases under Different Conditions

We have been using the heated filter concept for many years as an efficient way to extract a dusty gas sample and filter it prior to transportation to a gas analyzer. One of the reasons why we filter dusty applications at the extraction point is to avoid development of a dust / condensate slurry which would plug the sample tubing in and after the filter.

Our customers have had various combinations of conditions that have given rise to different configurations of heated filters as follows:

The standard heated filter is attached to a flue gas duct using a mounting flange. This configuration is suitable for samples at basically atmospheric pressure. The installation must be in a non-hazardous area. The cabinet requires a supply of instrument air or nitrogen to allow a blowback of the filter and the probe. This pushes the accumulated dust back into the flue gas duct.
The standard heated filter is also available in a hazardous area configuration. The heater is rated for hazardous areas and the electrical contacts are sealed in a small explosion-proof junction box.
Some high pressure processes, such as Direct Reduction of Iron (DRI), also require dust removal before gas analysis. We can provide a high pressure configuration of the heated filter system. However, this system does not allow blowback because of the high pressure in the process.
A version of the high pressure configuration is available that is suitable for hazardous areas.
Some sample points on a DRI process are also quite hot. It may be necessary to cool the sample slightly before it enters the filter. We can provide water-cooled spool pieces that are mounted between the probe and the filter valve.
We have also developed a vertical design which can be mounted on a duct or silo where the extraction probe is required to point downward into the gas atmosphere.

NOVA Heated filter system mounted vertically on a
process application at one of the US National Labs.
(Not our standard configuration, but worked
very well for this project.)

For information on these and other gas analyzer systems, give Mike or Dave at Nova a call, or send us an e-mail.

1-800-295-3771

sales at nova-gas dot com

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Thursday, December 20, 2012

#95 - Multi-Point Conditioning Systems for Mass Spectroscopy in DRI Plants

One of the unique projects we have worked on this year has been the development of conditioning systems for mass spectrometers at steel plants. The specific application is DRI (Direct Reduced Iron) plants, where iron ore is directly reduced to iron without the typical processes involving blast furnaces, coke ovens, basic oxygen furnaces, and other support plants. The DRI product can be used in electric arc furnaces (EAF) as a flexible additive to provide additional control over the end product or where the price and availability of scrap metal requires it.

DRI plants are quite large. The DRI product is fed into
bins which are positioned to feed directly into electric arc furnaces.

Mass spectroscopy is used by some steel makers to obtain analysis of their process gases. The main advantage of this technique is that it is versatile in terms of analytical capability. Numerous types of gases may be measured by a mass spectrometer.

Two challenges in coupling mass spectroscopy and steel processes such as DRI are the location and condition of the gas samples. Steel plants are usually sprawling industrial complexes with distances to some sample points being more than 250m (820ft). The condition of the sample is frequently hot, dusty, and under high pressure. For best analysis, the sample should be left intact, while managing the unwanted conditions.

Our solution to this dilemma has been to establish a primary conditioning system and a secondary conditioning system.

Primary Conditioning System

The initial task is to extract the sample while regulating it to a manageable pressure. Next, the sample needs to be filtered to remove particulate while it is still near the process temperature. A probe, flange-mounted isolation valve, and heated filter will accomplish these tasks.

Most projects have multiple sample points throughout the plant that require analysis. A primary conditioning cabinet needs to be mounted at each sample point.

Each sample line running from the primary conditioning cabinets needs to be maintained at a temperature above the dew point of the sample.

Secondary Conditioning System

The various sample streams must be collected, finish filtered, and distributed to the mass spectrometer. The entire cabinet and each sample line running to the mass spectrometer must be heated & temperature controlled. Each sample stream must have individual flow control and be alarmed for Low Flow condition.

In many cases, the entire system must be suitable for hazardous rated areas. Some systems must have provision to have each sample stream shut off in the event of a shelter atmosphere alarm.

The system configuration we have developed is designed for 8 simultaneous sample streams. We can accommodate more streams by adding cabinets as needed. The highest number of streams we have worked on so far is 13.

CUSTOMER: Al Nasser Industrial Enterprises

PLANT LOCATION: Abu Dhabi, UAE

Cooperating with us is HYL, a partner of Nova’s in the Tenova Group. HYL actively develops projects for direct reduction plants worldwide under the Energiron brand name. They started up the world's first successful direct reduction plant in 1957. Over 40 DR modules have been supplied worldwide since then.