News. Petrochemicals. Measure Sticky Samples Precisely With Heated Automation Units. Edition 02/2011

Transcription

1 Petrochemicals Weighing Analytical and solutions Analysis in the Laboratory laboratory 13 News Edition 02/2011 Measure Sticky Samples Precisely With Heated Automation Units The density, is commonly used to characterize petroleum products. Many petroleum products are highly viscous or solid at room temperature and therefore difficult to measure. The heated SC1H and SC30H automation units, in combination with the LiquiPhysics Excellence density meters, not only allow such determinations to be automated but also ensure measurement result reproducibility. Challenges in measurement More density determinations are probably performed in the petroleum oil industry than in any other industry. Hydrometers, along with digital density meters, are still used in many petrochemical laboratories in order to determine density. The reason for this is almost always the same: many samples are highly viscous or even solid at room temperature. Such samples are usually heated first to liquefy them and keep them warm enough to measure. The measured density values are converted to a reference temperature of 15 C or 60 F using official API temperature compensation tables. Hot samples can usually only be injected into the measuring cell of a digital density meter using protective gloves. As a rule, the sample is heated together with a glass syringe and the hot syringe is filled with the sample. The measuring cell is then filled using the syringe. One must be extremely careful not to inject too much sample as it will otherwise solidify at the cell outlet. For these reasons, it often seems easier to heat a larger amount of sample in an oil bath and to then determine the density manually using a hydrometer. However, density determinations of dark and viscous samples using hydrometers often yield poorly reproducible results. The reason for this are: Accurate thermo stating of the samples is not possible. Evaporation of volatile components cannot be avoided (open vessel). It is difficult to read the result because the hydrometer scale is often smeared with dark samples.

2 Density Determination The results (density at the reference temperature) must be determined from tables using linear interpolation. Improved accuracy With the LiquiPhysics Excellence density meters and the heated SC1H and SC30H automations units, METTLER TOLEDO offers ideal systems for petrochemical laboratories needing to perform accurate density determinations of highly viscous samples or even samples that are solid at room temperature. These systems allow the determinations to be performed automatically. The main advantages are: Hot samples are directly filled into vials. Hot syringes do not have to be handled. During measurement, samples are always in a heated environment and the measuring cell is filled automatically. Sample solidification at the cell outlet can safely be ruled out. The measurement cell is cleaned automatically after each measurement. Cleaning requires only small amounts of solvents and operators are not exposed to toxic solvents. Measured values are automatically converted to the desired reference temperatures according to ASTM D Even measurements of sample series can be completely automated with the SC30H sample changer. The systems are electrically heated. An external thermostat is not required. The new LiquiPhysics Excellence DM40 and DM45 density meters offer all the features necessary for hassle free density determinations at different temperatures. Text: Christian Iserland, Manager Business Area Density and Refractometry Publisher Mettler-Toledo AG Laboratory Division Im Langacher CH-8606 Greifensee, Switzerland Production Segment Marketing LAB Global MarCom Switzerland Subject to technical changes. Mettler-Toledo AG 08/11 Printed in Switzerland. 2

3 Accurate Standard Solutions Support Error-Free Fuel Analysis Excellence XP Analytical Balance The composition of gasoline or diesel is dependent upon the source of the crude oil, the refining method and the intended use. A German testing laboratory uses specially developed methods in LabX software to support their gas chromatography and HPLC analyses of these fuels. Complex samples Gasoline contains a mixture of hydrocarbons, including oxygenated hydrocarbons such as alcohols and ethers, as well as other additives in small amounts. Diesel is also a complex mix of hydrocarbons, obtained from the fractional distillation of crude oil, but typically has a higher number of carbon atoms per molecule than gasoline. The various constituents of both gasoline and diesel affect their performance as a fuel and are governed by strict regulations. The testing lab uses two different methods for preparing fuel solutions: one for preparing fuel formulations, and another for preparing fuel calibration solutions. The two processes are essentially the same. However, tolerance levels are much stricter for the calibration solutions and the results are displayed in parts per million (ppm) rather than as a volume percentage as for the formulation. Simple solution Each fuel solution can require up to 8 different individual components, all of which must be carefully weighed-in. The process is complex and prone to error. It is easy for the analyst to make a mistake in the dosage or even overlook a component. METTLER TOLEDO s new One Click Weighing Solutions, powered by LabX software, completely eliminates these types of error and makes the whole process much easier and faster. The methods were developed in close cooperation with the company and implemented in the software. The user simply calls up the method with one click on the Excellence XP/XS Balance touchscreen and LabX provides full step-by-step guidance directly on the balance. Secure process The required weight of each component is indicated on the balance display. The balance s SmartTrac guide helps to weigh-in the correct amount. If the value falls within the allowable tolerance, the balance display turns green. Upon confirmation, LabX saves the value and instructions for the next component appear on the display. LabX can be connected via the company network so no PC is required in the vicinity of the balance. It is also extremely simple to install any number of additional process safety measures e.g. secure identification of individual components with scanned barcodes or stepwise calculation and total weight control. Error-free conversion All measurement values need to be converted because weighing-in is conducted in mass units but volume percentages and ppm are specified in the standards. Step by step guidance This is usually carried out manually but with LabX this is no longer necessary. LabX stores the purity and density of all components and performs all the necessary calculations automatically. Potential transcription or calculation errors are eliminated. Documentation can also be tailored to individual customer demands to include mass percentages, tolerances, volume percentages or any other relevant data. Text: Stefan Christian, Group Leader Product Management Excellence Balances 3

4 Characterization of Diesel Exhaust Particulates Better Characterization of Diesel Exhaust Particulates The increasing number of environmental zones in large towns with stricter motor vehicle entry allowances, in combination with discussions concerning particulate emissions, is drawing increasing attention to pollutants released from diesel exhaust particulates. Particle filters in diesel vehicles have to be pyrolytically purged of the soot particles that have accumulated. This purge process can be optimized using the results of TGA/FTIR analyses. TGA/FTIR hyphenation for combustion analysis In order to determine both the quantity and type of gases released during such a heating process, a combination of thermogravimetric analysis (TGA) and a gas analyzer is ideal. TGA is an experimental technique in which the weight of a sample is measured as a function of temperature or time in isothermal experiments. The Fourier transform infrared spectroscopy (FT-IR) excels in gas analysis, which can be used to continuously examine a gas flow both qualitatively and, with the appropriate calibration, quantitatively. phase IR spectra can be of huge benefit here. If the gas types have been identified in this way, height profiles can be created across specific absorption bands as a function of the measuring time. These can then be compared with the TGA and DTG curves as shown in the following diagram. Combustion analysis The exhaust particulate sample was heated to 800 C at a rate of 20 K/min under nitrogen atmospheres followed by a switch to an oxygen purging gas to determine the carbon content via combustion. TGA/DSC 1 How it works The sample gas is rinsed from the furnace of a TGA/DSC 1 using a carrier gas stream (usually consisting of nitrogen or argon) and channeled into a gas vessel in the IR beam path via a heated transfer tube. IR spectra are recorded and saved as series at short intervals. Single spectra are then analyzed at particular points in the measurement in relation to typical IR absorption bands of functional groups in the gas mixture. A comprehensive library of gas Since carbon dioxide continues to accumulate after changing to oxygen at 800 C, the height profile for the wave number 2360cm -1 is hidden in this phase of the measurement. It is clear that, initially, both free and associated water from the diesel exhaust particulates accumulate to a combined total of 3.2%. With further heating, carbon dioxide is identified as the main gas emission together with low quantities of aliphatic hydrocarbons. Above 300 C, carbon monoxide 4

5 Figure 1: TGA and time differentiated curves (DTG, dashed-and-dotted line) above. The latter corresponds to the speed of the mass change. Height profiles of the typical IR absorption bands for the identified gas types below. and methane are also present. The total amount of gas released between 150 C and 800 C in this example is 27.3%. The carbon content following combustion in oxygen atmospheres is 67.6% leaving a residue of less than 2%. The diagrams on the right side show IR single spectra with the reference spectra of the identified gases. Conclusion As this example has shown, TGA combined with a FTIR spectrometer allows not only the quantity of the released gases to be determined but also the nature (identity) of the evolved gases formed in the TGA to be investigated online. This allows diesel exhaust particles to be analyzed more accurately. Based on this information, the regeneration (purge) process in catalytic converters of diesel vehicles can be greatly optimized. Figure 2: IR single spectra resulting from the combustion of diesel (black) and reference spectra of hexane (blue). Text: Dr. Dirk Neff, Product Manager, M-T Germany Figure 3: IR single spectra resulting from the combustion of diesel (black) and reference spectra of methane (green), carbon monoxide (brown) and carbon dioxide (red). 5

6 Weighing in Petrochemical Samples Robust Balances Withstanding Harsh Conditions Oily substances, sticky and acidic samples, corrosive atmospheres, and drafts the life of a laboratory balance in the petrochemical industry is certainly no picnic. XP and XS Analytical Balances from METTLER TOLEDO deliver precise and reliable results under these demanding conditions. With a long lifetime, these balances have simple yet innovative features designed to make daily laboratory processes so much easier. An Excellence Analytical Balance in use in a petrochemical lab. Demand robustness and high performance Numerous analyses are carried out every day in petrochemical laboratories and competence centers around the world. Metal, salt and sulfur content, concentration of volatile hydrocarbons and solid residue are the main attributes of interest. Typical analysis methods include x-ray fluorescence as well as traditional methods such as Karl Fischer titration. The samples are often extremely oily or sticky and may even contain harmful volatile hydrocarbons and highly toxic components such as polynuclear aromatic hydrocarbons (PAHs). This means working with highly acidic solutions and exposure to corrosive vapors. Laboratory personnel, therefore, need to wear thick rubber gloves and conduct the sample preparation in special extraction cabinets. However, the balances placed in these cabinets are unprotected. The seals, displays, metal surfaces or electronic parts are often attacked by solvents or highly corrosive vapors. METTLER TOLEDO balances deliver perfect results over their long lifespan for three important reasons: innovative solutions, the highest quality materials and exceptional production quality. 6

7 Know-how Convenient functions make life easier Special features of XP and XS Analytical Balances, such as our SmartSens infrared sensors, SmartGrid weighing pan, and ErgoClip tare container holders, ensure that each balance performs to its full potential in the harsh conditions of the petrochemical industry. Automatic opening of the weighing chamber door facilitates simple handling and the touchscreen is easy to use even when wearing thick rubber gloves. Extraction cabinets generate a permanent airflow around the balance to remove potentially dangerous vapors from the cabinet. XP and XS Analytical Balances are unaffected by these air currents as the SmartGrid weighing pan is uniquely suspended from the rear of the balance, inside the balance s own weighing chamber. The balance settles quickly and provides reproducible measurements. The SmartGrid system is extremely easy to clean: the weighing pan and tray below simply lift off. None of the balance mechanism is underneath so any spilled sample material cannot enter the balance interior. The robust balance housing is chemically resistant and the terminal also has a protective cover. connected balances. LabX guides the users through each process with step by step instructions on the balance. Laboratory managers can be sure that each method and SOP has been followed precisely. It is no coincidence that XP and XS Analytical Balances from METTLER TOLEDO have an excellent reputation in the petrochemical industry with such innovative solutions, high production quality and absolute durability. Text: Daniel Fuchs, Head of Market Management Team Make the most of your balance with professional accessories Everyday laboratory routines become easier and quicker with help from simple accessories. Sophisticated applications require special accessories to match specific process needs. METELR TOLEDO s accessories are developed with the clear focus of meeting application requirements and/or specific weighing tasks. These helpful options are presented all together in one easy reference booklet. Download the new Excellence Accessories booklet to see the comprehensive range designed especially for your balance. Perfect network integration All balances can be linked through LabX software. Barcoded samples can be immediately identified in the analysis and all data is collected and saved automatically to ensure a high level of security. This is of particular benefit in the competence centers where hundreds of balances are often in use simultaneously. Developed analysis methods and standard operating procedures (SOPs) can be implemented directly into the software and then be called up when required by all Excellence Plus XP205 lab-excellence-accessories 7

8 One Click Operation Simplify Your Daily Routines With One Click Many lab instruments require multiple steps to get an analysis or other processes started. This can be a true hassle especially for routine operations, but also makes it hard to use instruments for infrequent users. Therefore METTLER TOLEDO has worked with its broad user base to develop One Click operation: All your routine tasks are executed at the press of One Click! See how it works Karl Fischer Titrator The home screen of the instrument shows all the key tasks of a certain user If a key is pressed, the complete routine is started. No further confirmations and configurations are needed: Just One Click. All the common routines of a user can be a One Click operation e.g. measurement, calibration routines, data evaluation, cleaning procedures etc. The home button on the instrument brings the user always to the home screen, nobody can get lost in the user interface Refractometer 8

9 Analytical Balance Excellence Titrator Density Meter Melting Point One common operation interface across all key Lab instruments Most of the METTLER TOLEDO instruments share the same One Click user interface. This means e.g. that once you know using a titrator it s very easy to use a density meter or melting point instrument as well. Key benefits of One Click operation: Easier and faster execution of tasks Each user sees only the functions/actions he needs Routine users e.g. in production only see what they need and are not confused by unneeded functionality Operation mistakes are avoided SOP are automatically followed Less training is needed See One Click in action in this short video: 9

10 Product News All 5 glass panels are removable, for easy access and cleaning. The draft shield mounts easily onto the balance. Increased Weighing Performance in Drafty Environments Up to 2 unused glass panels can be conveniently stored at the back of the draft shield frame. The optional draft shield fits both NewClassic and Excellence Balances. Petrochemical production lines are often very drafty places. There can be air currents from heaters and ventilators, people walking by and plenty of other contributors to air turbulence making it difficult for a balance to deliver quick and precise results. Fitting the new, handy draft shield for precision balances noticeably increases weighing accuracy resulting in faster settling times. Chemical Resistant The housing of the NewClassic balance is resistant to most chemicals, incl. acetone. The protective cover, supplied as standard, offers protection against stains and scratches. Dishwasher Safe Wash the glass panels of the draft shield easily and conveniently in the dishwasher. 10

11 Level Sensor for Solutions and Waste Security in Your Lab Various solutions are involved in the preparation and analysis of petrochemicals samples. Solvents and other auxiliary reagents can often be very toxic and the operators handling them need to take particular care. The innovative LevelSens is simple to install and use and greatly increases security through solution monitoring. Placed on the outside of the waste bottle, it reliably detects the solution level inside without coming into contact with chemicals. V30 Compact Volumetric KF Titrator Prevents overflow Waste solution is often pumped into a waste bottle after each measurement. LevelSens interrupts the series when this bottle is full. Overflow is reliably prevented to increase security in the laboratory. Solution monitoring If a titrant, solvent or auxiliary reagent bottle runs dry, the titration is not performed correctly. LevelSens interrupts the series and the instrument prompts via a displayed message in order to prevent lost samples and wasted time. Easy installation LevelSens is easily attached onto the outside of a bottle. It has no contact with reagents and isn t damaged by aggressive chemicals. Its plug and play set up is very simple with no complicated settings to deal with. 11

12 Hints & Tips Comprehensive Guide for Day-to-Day Titration Practice What is the most effective way to get the best titration results? METTLER TOLEDO's Hints & Tips brochure, which forms part of the 'Good Titration Practice ', provides information on the parameters that influence the accuracy and repeatability of titration results. It also recommends correct titration practices for secure operation and to maintain quality results. Content highlights: Important aspects of general, coulometric and volumetric titration systems. Hints and Tips for daily use. Theoretical description of GTP influencing factors, e.g. types of errors, reagent handling, how to get the best titration results. Simply sign up to receive a free hard copy of the brochure! To estimate titration result reliability go to: Mettler-Toledo AG Laboratory Division Im Langacher CH-8606 Greifensee, Switzerland For more information