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Thursday, December 27, 2012

#96 - Pictures of Extreme Cold Weather Analyzer Package

Outside Nova facility after
Dec 27, 2012 snowfall.

Last night’s snow storm that hit the North-Eastern US / Toronto / Niagara regions reminds me of our ‘extreme cold weather package’.
 
Gas analyzers and many other scientific instruments usually do not like the cold. If a gas sample has condensable moisture in it, there is a possibility of ice build-up in the wetted sample train. The electronics, valves, and detectors all prefer to function at approximately room-temperature or slightly higher.
 
Periodically, we have had requests from companies who are operating outdoors in the cold northern areas of North America and Europe. To cope with this reality, we came up with our Cold Weather Package a few years ago. The package includes a durable outdoor cabinet with a windowed door, cabinet insulation, and internal heaters. We generally specify this design for outdoor temperatures as low as -20°C (-4°F). We recommend that the analyzer be sheltered from the wind and sun. This will help stabilize the cabinet temperature and reduce temperature swings.
 
Every once in a while, we have customers who want to operate in even colder temperatures. We meet these requests by installing our ‘Extreme Cold Weather Package’. This package also has an outdoor cabinet, insulation, and heaters. We just add more of everything. The cabinet door is modified to replace the large window with a smaller window and insulation. We generally specify this design for outdoor temperatures as low as -32°C (-25°F). However, we have seen some of these packages installed on sites as low as -40°C (-40°F). We’re not sure how well these units are working. For some reason, no one ever wants to go outside and check on them when it gets that cold!
 
One thing that is really important on cold sites is heat-traced tubing. The input sample line, vent line, and drain lines should all be heat-traced to prevent ice build-up. Obviously, ice build-up in the lines will cause low flow conditions and other problems.
 
Pictured below is a cold weather unit that we sent recently to a Canadian site in Terrebonne, Quebec.
 
'Extreme Cold Weather Package' protects analyzer
from cold outdoor temperatures.


Gas analyzer display is still visible with cold
weather cabinet modifications.
 
Cold weather operation brings challenges. No doubt about that. However, we can manage those challenges by adding heat and insulation to the design.
 
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
websales 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.
 
 
 
 
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
websales at nova-gas dot com
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Thursday, December 6, 2012

#92 - Metamerism – Part 2

Last time, the topic of metamerism as related to the coatings industry was discussed. We don’t really have any issues with metamerism in manufacturing gas analyzers, but the whole idea reminded me of some challenges that we do face in the analysis of atmospheric gases.

Analytical Interference

Various methodologies lend themselves to analysis of different gases. Some methods are more or less specific than others, and there is usually no ‘magic bullet’ sensor/detector for any one gas.

Hydrogen – At Nova, we offer analysis of percent hydrogen by thermalconductivity detector. Hydrogen has a high degree of thermalconductivity, and this property can be used to measure it. However, other gases also have various degrees of thermalconductivity. The presence of several other gases in a mixture can interfere with the effectiveness of a thermalconductivity measurement. For hydrogen applications, we need to know what other gases are in the sample and the low/normal/high levels of each.

Methane & Hydrocarbons – At Nova, we offer infra-red analysis of hydrocarbons. The most common infrared analysis requested of us is methane. If the sample contains methane and enough other mixed hydrocarbons, some of the non-methane constituents will also produce a response on the infra-red detector. This is because many hydrocarbons have similar or overlapping IR spectra.

The methane reading may be compromised to an unknown degree by the non-methane hydrocarbons. For methane applications, we need to know what other gases are in the sample and the low/normal/high levels of each. We may be able to offer a methane-specific detector. In some cases, we may be able to compensate for the problem using certain calibration gas blends. Sometimes we can ignore the whole problem if the effects are not sufficient to be of concern to the end-user.



Electrochemical Sensors – At Nova, we offer analysis of various gases, including oxygen, using an electrochemical sensor. Electrochemical sensors are reactive by nature and are frequently affected by gases other the one of interest. For example, the gases carbon monoxide and hydrogen will often provoke a strong response on the same electrochemical detector. For electrochemical applications, we need to know what other gases are in the sample.

All of this really isn’t metamerism, but the ideas and potential consequences do bear some similarities. When discussing your analytical needs with Nova, we may request that you fill out an Application Questionnaire. This form is intended to assist you to provide us with critical data that may influence the type of equipment that is feasible in your application.



Nova Application Questionnaire
http://www.nova-gas.com/appq.html


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
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/

IR Spectrum:
NIST Chemistry WebBook (http://webbook.nist.gov/chemistry); COBLENTZ SOCIETY; Collection (C) 2009 copyright by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved.
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Thursday, November 29, 2012

#91 - Part 2 of “Post #5 is our most popular blog post”

I mentioned recently that Post #70, which was called “Post #5 is our most popular blog post (Syngas and Gasification)”, has itself now become our most popular post. I guess if you say something is popular, that proclamation alone is enough to pique some interest.

Another reason for the popularity is probably because of its topic - syngas and gasification. Specifically, the analysis of syngas composition.

In this application, the critical gases are H2 and CO. However, most of our gasification customers want analysis O2 / CO / CO2 / CH4 / H2. We can offer this combination of gases in any range in a single analyzer.





Here’s one that we are building now to support a Fischer-Tropsch process in which H2 & CO are converted into hydrocarbons in the presence of a catalyst.







As a follow-up to Post #5 and Post #70, we have another update to offer on this topic:

Besides having a capable analyzer for this application, it is also important to condition the sample properly before analysis. 
 

Hot Extraction and Filtration

Depending on the feedstock being used in the gasifier, the sample may have a significant amount of particulate in it. It is important to remove the particulate before condensation develops and mixes with the particulate. A heated filter that is mounted behind the probe at the extraction point is a good solution. A version of this filter can even be produced for high pressure samples or for Class 1 Division 2 Hazardous Rated Areas.
 
 
 
Tars
 
Many of our customers have reported to us that if the feedstock is comprised of woodchips or other wood-based matter, there is a strong possibility of tar being in the sample gas. These tars may condense out onto various surfaces. Especially of concern are the optical surfaces of the detectors. We have had some success in removing tars by integrating a gas cooler in a separate cabinet beside the analyzer. This encourages the condensable tars to accumulate on a non-critical surface away from the detectors. Ideally, the cooling assembly should be somewhat modular to allow easy access for cleaning or replacement.
 
Theoretically, a chemical scrubber can also remove the tars. But some of the solvents that might be used, isopropyl alcohol for example, may be carried into the analyzer and provoke a response on the infrared detector. This can be interpreted and presented by the analyzer as a falsely high CH4 reading. So we have been cautious about IR analyses where these types of scrubbers are installed. If the scrubbing solvent is water-soluble, a possibility might be to integrate a water-wash system in front of the analyzer as discussed below. (We haven’t tried this solution yet in this context, but it is an interesting idea.)
 
 
Soluble Gas Removal
 
On some projects where the feedstock is municipal waste with high variability, we have noticed the presence of other gases besides just H2, CO, & hydrocarbons. For example, there may be SO2 or NH3 in the sample gas. These gases may be detrimental to the long-term operation of the analyzer, so it is frequently best to eliminate these gases from the sample. On some gasification projects, we have supplied water-wash systems to scrub out any corrosive gases that are water-soluble.
 
 
 
Multiple Gasifiers or Multiple Sample Points on a Gasifier System
 
Sometimes analysis of multiple points with one analyzer is required. We have supplied an industrially-hardened version of our auto-sequencer for some gasification projects. This system will continually pull a sample from several sample points and send only one at a time to a single analyzer. The auto-sequencer will cycle through the sample points according to a user-defined schedule. Generally, the dwell time on each sample is a few minutes.
 
 
 
 
 
 
 
 
 
 
Not sure if this post will become as popular as the other gasification-related posts. But we will try to continue providing updates on Nova solutions for this interesting application.
 
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
websales at nova-gas dot com
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Thursday, November 22, 2012

#90 - Metamerism – Part 1

“Metamerism” is primarily a chemistry term for a type of isomerism in which chemical compounds have the same molecular weight and identical proportions of the same elements, but have different chemical properties because of radicals of different types or in different positions. Sounds complicated, but it’s basically a reference to two chemicals that you would expect to behave the same, but don’t because of minor differences.

In the coatings industry, especially in pigmentary studies, metamerism has a somewhat different meaning, but the idea is still sort of the same. Metamerism is a term used for when two colored samples appear to match under one set of lighting and viewing conditions, but not under another set. Metameric dissimilarity may also be due to differences in observers’ color perception aside from lighting or viewing conditions.

There are instruments available that simulate
various lighting and viewing conditions to
help manage unexpected metameric effects.

I have noticed that metameric effects are often more pronounced in coating systems that do not have high opacity and where the substrate is colored (non-white), or where the system is comprised of multiple layers of varying color contribution. Coatings that incorporate different types of coloring material types also seem prone to metamerism (e.g. organic/inorganic colorants or dyes/universal colorants added post-manufacture).

An example scenario might be a manufactured article whose color is designed and agreed to under the viewing conditions at the manufacturing facility, but doesn’t match expectations when the article is completed and moved to the final location. Metamerism may be the reason. (I say ‘may be’ because a legitimate manufacturing error may also be the cause.) During my time in the coatings industry, I dealt with metamerism often enough to appreciate its potential for disruption.

At Nova, we are thankful that we do not have to worry about such aesthetic complexities in our manufacturing process. Making gas analyzers is complicated enough already. But there are a couple of phenomena in gas analysis that remind me a little of metamerism. I’ll talk about those next time.

The Nova blog appears to be about gas analyzers, and yet this post discussed a completely different subject. Literary metamerism.

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
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/

Pictures:
Copyright © INTEKE INSTRUMENT CO. LIMITED
 
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Monday, November 5, 2012

#86 - New Nova Video on Youtube

Very low budget video made at Nova 'studios' and posted on YouTube.




http://www.youtube.com/watch?v=3uhQH9RcJ6U

It is a 3-min presentation intended to briefly show some of the value proposition inherent in Nova continuous gas analyzers.

NOVA Analytical Systems
1-800-295-3771
sales at nova-gas dot com
websales at nova-gas dot com

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Thursday, November 1, 2012

#85 - Caribbean Applications

A couple of my holiday shots. The pictures shown below are of the Noranda Bauxite Mine in St. Anne, Jamaica.


The last time in Jamaica, I drove by this facility and wondered what it was. I subsequently learned that it is part of a bauxite mine facility. Apparently after tourism, bauxite mining and agriculture are Jamaica’s largest industries. Coincidentally, I recently had a telephone call from the Superintendent of this very facility.
 
Copyright © 2007 – 2009 Noranda Aluminum. All Rights Reserved.
 
They apparently have a few diesel engines operating in individual rooms in the plant. The engine exhaust is obviously vented outside of the building. However, if a leak should develop in the exhaust system, it may result in dangerous accumulations of gases inside the building.
 
For the safety of their staff, they wanted to monitor the following gases:
  • Oxygen Deficiency: 0-25%, alarms will sound if the O2 levels drop to 19.5% or lower
  • Carbon Monoxide: 0-200ppm
  • Nitric Oxide: 0-100ppm
  • Sulfur Dioxide: 0-20ppm
These ranges of analysis cover the safe breathing conditions and permissible exposure limits of these gases.
 
To start, they have 3 engine rooms and they want to have some kind of centralized monitoring system. An auto-sequencer will be a good choice here. It is mounted right beside the monitor. This device is basically a series of solenoid valves and pumps which are controlled to pull different samples from different zones in a timed sequence. This will allow one monitor to be used for all three areas.


Eventually, they hope to tie the monitor / sequencer in with a PLC or a data collection system of some kind. But for now, labeled LED lights on the auto-sequencer will show which area is being sampled. And the monitor will show if any alarms are engaged.
 
We sometimes may forget that some of the Caribbean islands have other sustaining industries besides tourism. These regions no doubt struggle with a delicate balance of having profitable industry while preserving the beautiful environments that attract so many travelers.
 
We are occasionally contacted by Caribbean engineers & professionals for emissions analyzers. For example, in Trinidad and Tobago, we have sold continuous and portable flue gas analyzers into the petrochemical and gas process industries there. Legislative initiatives are apparently also moving these islands toward reductions in automotive exhaust emissions. We have also had requests from Curacao for information on emissions analyzers. Cutting back emissions is a good idea anywhere. But in areas that depend so much on pristine environmental beauty, it would seem to be nothing short of mandatory.
 
Nova Analytical Systems
1-800-295-3771
sales at nova-gas dot com
websales at nova-gas dot com
 
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Thursday, October 18, 2012

#83 - TGI Whitepaper - BOF End-Point Prediction

By Joseph Maiolo and Doug Zuliani
 
Using a process control and optimization system first developed for EAFs, an advanced statistical methodology can predict end-point carbon from off-gas composition trends and process parameters.
 
The Expert Furnace System Optimization Process (EFSOP®) developed by Tenova Goodfellow Inc. (www.tenovagroup.com) is a dynamic process control and optimization system based on the real-time measurement of off-gas composition. Originally developed for electric arc furnaces, it has been applied recently for end-point control in basic oxygen furnace steelmaking. Through a three-year funding grant from Sustainable Development Technology Canada, a not-for-profit foundation, this first EFSOP system for the BOF was installed on a 165-ton BOF, used to convert a nominal mix of 120 tons hot metal and 45 tons of scrap into high-performance automotive steel.

Figure 1: Schematic of the EFSOP system applied to a basic oxygen furnace.
 
The EFSOP installation for oxygen steelmaking is shown in Figure 1. The system is made up of: • A patented water-cooled off-gas sampling probe.

  • The EFSOP off-gas analyzer, for sample conditioning and analysis. A customized purging system keeps the probe clear of dust and eliminates plugging.
  • A passive infrared gas pyrometer(s) for off-gas temperature.
  • A supervisory control and data acquisition (SCADA) system.
The sampling probe, designed to withstand the harsh conditions of steelmaking, is installed through a port in the panels of the BOF fume system. The probe is located sufficiently downstream of the combustion gap to ensure that the sampled off-gases are mixed completely and combusted. The gases are drawn through a heated sample line to the EFSOP analyzer, where they are analyzed in real-time for oxygen, CO2, CO, and hydrogen. Two infrared pyrometers, one located at the combustion gap and a second one at the downstream sampling location, are used to measure the temperature of the off-gas at the two locations.

This first application of the EFSOP analysis system proved highly reliable, with over 99% uptime. In addition to sampling and analysis, the EFSOP analyzer performs a secondary function of controlling the back-purging of the sampling circuit. To ensure a valid off-gas sample throughout the blowing period, the system is only purged during natural breaks in the process (e.g., during charging and tapping). This is more than sufficient to keep the probe from plugging.

Composition measurements, as well as operational alarms and outputs from the analyzer are linked to the plant’s PLC network. The EFSOP SCADA computer is linked to the same network and reads and logs off-gas data, as well as all relevant process data at a frequency of one second. In total over 300 BOF parameters are sampled and logged in real time. Both historical and real-time plots of the data are made available to the operator. Off-gas data, process data, and EFSOP system alarms are emailed to Tenova Goodfellow, allowing process engineers to follow the operation remotely.

Figure 2: A profile of the measured downstream off-gas composition and temperature for a typical heat.

Figure 2 shows a sample plot of the measured off-gas composition and temperature profile for a random heat. The pattern displayed is typical and fairly consistent from one heat to the next. This BOF vessel operates with an open-combustion system (not the more common, suppressed combustion system found in most BOP shops), which explains the high levels of oxygen and CO2 indicated in the figure. Large variations in the off-gas composition at the start of the heat are typical for this shop. The variation is due to that affect of additions (e.g. lime) to the vessel at the start of the blow and pre-ignition conditions in the off-gas. The off-gas temperature is fairly constant over the course of the heat and varies from 1,600° to 1,800° Kelvin, except for the sharp decrease at the end of the heat. Very little CO and hydrogen are present, indicating complete combustion of the off-gas with air entering the combustion gap. After ignition, the CO2 ramps up as the lance is lowered and decarburization begins. The slight delay is attributed to the early oxidation of elements with a higher affinity for oxygen than for carbon (e.g. Si, Mn). Near the conclusion of the heat, both CO2 and temperature diminish significantly as carbon is depleted. The pattern is mirrored in the concentration of oxygen.

End-point detection

A primary objective of BOF steelmaking is to achieve some desired end-point temperature and grade composition at the lowest cost and in the shortest time. To do so, operators rely on standardized BOF practices and static charge models. These models are mass and energy balances that account for the initial conditions (scrap and hot metal temperatures and compositions) and the desired end-point conditions of the bath and slag, and indicate to the operator the expected total oxygen and fluxes that are required to reach that end-point. The blow is stopped once the pre-determined amount of oxygen has been reached. In addition to the charge model, the operator relies on other cues, such as the change in the color of the flame at the mouth of the vessel and a characteristic drop in the steam flow in the fume system cooling circuit, to identify when carbon has been depleted.
 
In practice, static charge models have a limited ability to predict end-point because they do not account for process dynamics. End-point accuracy also is affected by uncertainties in the initial conditions (e.g. mass, temperature and composition of the hot-metal, mass and type of scrap and fluxes added) and by variations in the efficiency of the oxygen lance, not only within a heat as the height and flow of the lance is varied, but also from heat to heat as the lance wears and the geometry of the vessel changes with refractory wear.
 
The limitations of the charge-model based end-point determination are demonstrated in Figures 3a and 3b, showing the error between the aim and measured end-point. The data was collected over one month of operation and is based on 400 heats. Temperature and bath carbon were measured by “bomb Celox” samples taken at the conclusion of the heat, as dictated by the charge model.

Figure 3: Error distribution in end-point carbon and temperature, using the charge model.

Figure 3a is a histogram of the error in carbon (measured as points of carbon, i.e. % × 100). The average error is about 0.1 points of carbon with a standard deviation of 0.8. The measured carbon at first sample was, on average, lower than the aim. This particular operation tends to over-blow its heats, with respect to carbon. Figure 3b is a histogram of the error in temperature (measured in °Celcius). As indicated in that figure, the average error in temperature is -20°C with a standard deviation of 25°. The temperature at first sample was, on average, higher than the aim; indicating that the heats are also over-blown with respect to temperature. Over-blowing impacts not only yield and productivity but also has a significant environmental impact.
 
If too much carbon is removed from the bath it must be replaced in the ladle to meet cast specifications. The extra carbon, first removed and then replaced, unnecessarily contributes to additional greenhouse gas emissions. Despite the tendency to overblow, approximately 7% of the heats were found to be more than 1 point of carbon above the aim; meaning that the operator had to re-blow the heat after the first sample.
 
EFSOP end-point detection
 
The EFSOP strategy for end-point detection uses real-time off-gas composition, along with measured process variables, to determine more accurately when the temperature and carbon end-points have been reached and signal the end of the heat. The online information is used in two ways: Advanced multivariate statistical modeling of the process; and dynamic state-space modeling of the process.
 
The statistical component, of the EFSOP end-point predictor, is based on the fact that the off-gas profile is fairly consistent, from heat to heat, with respect to shape. It is well accepted that the kinetics of decarburization are driven by the rate of mass transfer of dissolved carbon to the reaction interface between liquid metal and iron oxide. At high carbon concentrations (approximately greater than 0.3% carbon), the mass transfer rate is sufficiently high that the rate of decarburization is controlled by the rate of oxygen supply to the steel bath. Below this concentration, the rate of decarburization is limited by the rate of carbon diffusion to the reaction interface. This mechanism is evident in the off-gas profile where CO2 concentrations tend to remain fairly constant throughout the heat, and then to decrease sharply as carbon is depleted near the end of the blow.
 
This feature, along with other process inputs, was used to develop a statistical model of the profile of decreasing carbon consumption at the end of the blow. An evaluation of the methodology was conducted to determine the accuracy with which bath carbon is predicted. Over 200 heats were evaluated off-line. Figure 4 plots the results and shows the cumulative percent of heats that fall within the error interval indicated. The error is determined as the absolute difference between the predicted carbon and the measured carbon. The figure shows that the statistical model for carbon end-point is able to predict within one point of carbon about 95% of the time. This is a significant improvement over the plant’s historical operation, in which the carbon end-point was within one point of the aim for only 85% of the time.
 
The EFSOP dynamic model component makes use of real-time off-gas composition to calculate a dynamic mass and energy balance over the course of the blow — unlike the static charge model approach, in which only initial and final conditions are taken into account. The off-gas composition and temperature are used to calculate, in real-time, carbon, oxygen and enthalpy balances of the gas-phase of the process. From the carbon balance, the rate of decarburization is determined over the course of the blow. The oxygen balance provides information not only of the total rate of oxidation, but also the extent of post-combustion (CO to CO2) and the relative fraction of oxygen reacting with either bath carbon or participating in slag-forming reactions. An enthalpy balance of the gas phase makes it possible to calculate energy leaving the system with the off-gas. Any remaining energy is either lost through the walls of the vessel or attributed to heating the bath/slag or melting and heating of scrap.

Figure 4: Cumulative distribution of the prediction interval using EFSOP end-point model.
 
Predicting end-points accurately is improved with the use of dynamic off-gas information, which makes it possible to estimate the properties of the bath and slag over the course of the heat. The EFSOP advantage over static charge models, where only initial and final conditions are taken into account, is that the off-gas information provides a measure of oxygen utilization over the course of the heat and allows a dynamic evaluation of the actual efficiency of the oxygen imparted to the process for both bath refining and post combustion. Variability in the efficiency with which oxygen is delivered to the bath is not unexpected and is affected by lance wear, variations in the height of the lance, variations in the lance rate, refractory wear, among other factors.

The greatest challenge encountered in the development of the dynamic model has been tuning the model to the process. The accuracy in the initial conditions (i.e. initial mass and composition of scrap and hot metal), as well as the accuracy in the measured final bath conditions (i.e. measured end-point carbon and temperature and slag analysis), will influence significantly the predictive ability of the model. Uncertainties in the precision of the input data are common in steelmaking, however the current EFSOP installation confirms that efforts to improve input data precision will ensure a reliable tool for end-point prediction.

Future work

Off-line evaluation of the EFSOP approach to end-point prediction indicates that carbon end-point can be identified with greater accuracy than is possible with the plant’s current charge-model approach. The EFSOP off-gas based statistical model is able to predict carbon within one point of the measured value, for 95% of cases. Based on these results, the plant has implemented the EFSOP off-gas system online for end-point carbon prediction. Online trials have started and are on-going at this writing.

A dynamic model of the BOF process, based on real-time offgas measurements, has been developed and tuned. The model is being validated off-line and initial results are promising.

In a subsequent phase of this project the EFSOP off-gas analysis system will be used to control post-combustion in the BOF vessel. Building upon its successes in optimizing post-combustion in EAF steelmaking, Tenova Goodfellow aims to develop a system to control and optimize post-combustion in the BOF. The off-gas model provides a dynamic measure of the extent of post-combustion occurring naturally in the process. Intentions are to use this information, in a feedback approach, to control both oxygen flow (primary for decarburization, and secondary for post-combustion) and lance height, in a dual-flow oxygen lance. It’s expected that energy recovered through the implementation of postcombustion will allow an increase in the scrap to hot-metal ratio to increase productivity in this hot-metal short operation. A reduction in the hot-metal to scrap ratio also will provide environmental benefits by reducing greenhouse gas emissions (kilograms of CO2 per ton of steel produced) from the integrated blast furnace/BOF process, measured as total CO2 per ton of steel produced.

Joseph Maiolo is the manager of Technology & Development, and Doug Zuliani is the director of Sales & Business Development, both with Tenova Goodfellow Inc., Mississauga, ON. Contact them at goodfellow@ca.tenovagroup.com

http://www.tenovagroup.com/
6711 Mississauga Road, Suite 200
Mississauga, ON, L5N 2W3 Canada
Phone +1 (905) 567 3030
Fax +1 (905) 567 3899

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Friday, October 12, 2012

#82 - Arcelor Mittal Chooses Tenova Again

ARCELOR MITTAL ONCE AGAIN CHOOSES TENOVA MELT SHOPS TO SUPPLY A LADLE FURNACE OF 300 TONS CAPACITY.
 
Milan, August 30th, 2012 - Tenova Melt Shops has recently been contracted by Arcelor Mittal to provide the turnkey supply of a 300 tons Ladle Furnace that will operate in integrated cycle in the Arcelor Mittal plant (ex Sidmar) located at Gent, Belgium, and specialized in high quality steel for automotive sector.


 


The turnkey technology will be operative in December 2013. This contract follows the Twin Ladle Furnace of 320 tons already supplied in 2006 to Arcelor Mittal Poland for the plant located at Dabrowa Gornicza and confirms the high reliability of Tenova Melt Shops technology.
 
Arcelor Mittal, Dabrowa Gornicza, Poland
Sidmar aka Arcelor-Mittal, Gent, Belgium
 
Tenova is a worldwide supplier of advanced technologies, products and engineering services for the iron & steel and mining industries providing innovative, integrated solutions for complete process areas. Tenova's network companies operate in 26 countries on 5 continents with more than 4,900 people.
 
For more information visit the company’s website at http://www.tenovagroup.com/
 
For information on 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
websales at nova-gas dot com
 
 
Ghent photo By Peter Dedecker, some rights reserved, Copyright © 2008
Dąbrowa Górnicza photo by Petr Štefek Copyright © 2008
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Thursday, October 4, 2012

#80 - Unique Application – Portable 8 Channel CO analyzer

There is a saying that a person with two watches never knows what time it is. What about someone with 8 watches?
 
A few years ago, we had an inquiry from a major automobile manufacturer for a multi-channel carbon monoxide analyzer. It had to have 8 separate channels of gas analysis and it had to be portable. The 8 channels were to be isolated from each other and have separate displays for each reading. This instrument was essentially 8 analyzers in one. The only common parts were the cabinet and some power supply components.
 
The intended use for this unusual instrument was to monitor 8 separate zones inside an automobile while driving on the test track.
 
 
 
The analyzer was ranged as follows:
Channels 1-6: 0-500 PPM CO
Channels 7-8: 0-2000 PPM CO
 
There was an individual 0-5V recorder output for each channel. The analyzer outputs were to be connected to the customer’s data recorder so that the entire test track results could be uploaded later to a personal computer for data analysis.
 
Each channel had its own sample pump and flow meter. So the instrument actively pulled the samples to itself through a tubing bundle which was extracting from each zone of interest in the automobile.
 
The response time was about 20-30 seconds per 90% of step change. The electrochemical sensors used in this instrument were customer-replaceable.
 
We thought that this analyzer was odd enough that we would likely never build one again. We were wrong. Copies of this analyzer have been purchased several times since by major auto manufacturers around the world.

Addendum Jan 31, 2013 - We just completed another two of these units for another major auto manufacturer - this time for General Motors in the USA. Two further clarifications:
  • The instrument has the Sample In ports located on the front of the cabinet for easy access to the operator. The Vents are located on the back of the cabinet.
  • There are 0-1V recorder output connections for each channel located on the front and the back panels. Again, this is for easy access for the operator.



 
Here are the Specifications :
 
METHOD OF DETECTION:
Customer replaceable electrochemical sensors

RANGES:
Readout 1-6: 0-500 PPM
Readout 7-8: 0-2000 PPM
 
RESOLUTION:
1 PPM in PPM Range
 
ACCURACY AND REPEATABILITY:
Better than 1% of full scale, based on a 0-2000 PPM range
 
DRIFT:
Less than 1% of full scale per day
 
RESPONSE TIME (T-90):
20-30 seconds per 90% of step change
 
AMBIENT TEMP. RANGE:
0-50°C (32° to 122°F)
 
LINEARITY:
Better than 1% of full scale
 
POWER:
12 VDC and rechargeable battery option
 
OUTPUT OPTIONS:
0-5 V
 
 
 
 
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
websales at nova-gas dot com
http://www.tenovagroup.com/


Test track photo copyright © 2009 Truss, Bob & Jan of Holland
Bus test track photos Copyright © 2009, Mercedes-Benz-Blog. All rights reserved.
http://mercedes-benz-blog.blogspot.ca/2009/02/setra-s-411-hd-as-visitor-bus-at.html
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