Khan S.,University of Leeds |
Ma C.Y.,University of Leeds |
Mahmud T.,University of Leeds |
Penchev R.Y.,University of Leeds |
And 11 more authors.
Organic Process Research and Development | Year: 2011
A measurement-based closed-loop control system using in-process ATR-FTIR spectroscopy coupled with a multivariate chemometric PLS calibration model is developed, validated, and applied to the monitoring and control of supersaturation in a 250- L industrial pilot-plant crystalliser. Supersaturation control experiments are carried out on seeded batch cooling crystallisation of β-l-glutamic acid from aqueous solutions using two methods of seeding involving addition of seeds to the solution and generation of seeds within the solution. The generic applicability of the approach is demonstrated through this challenging system reflecting this molecule's weak chromophore for infrared and relatively low solubility compared with previous solute-solvent systems. Based on the laboratory experiments, the system was fully tested and optimised prior to a series of trials carried out in an industrial pilot plant at Syngenta, Münchwillen, Switzerland. Good control of the supersaturation is achieved at three levels, 1.1, 1.2, and 1.3, within a prescribed range of ±0.025. The average product crystal size is found to decrease with increasing supersaturation. Comparison between product crystals produced at the 20- and 250-L scales indicates that secondary nucleation is more prevalent at the smaller-scale size. For the same level of supersaturation, the rate of depletion of solute is faster at the 20-L scale size than at 250-L scale, and hence a higher cooling rate is required to maintain the desired supersaturation. However, for a given crystalliser scale size, as expected, the mean cooling rate required to maintain a constant supersaturation is found to increase with increasing supersaturation level. © 2011 American Chemical Society.
Kossoy A.A.,ChemInform Saint Petersburg CISP Ltd. |
Singh J.,HEL Ltd |
Koludarova E.Y.,ChemInform Saint Petersburg CISP Ltd.
Journal of Loss Prevention in the Process Industries | Year: 2015
The paper represents some results of comparative analysis of the methods used for processing and interpreting data of adiabatic calorimetry as well as applying it to practical situations. Specifically two approaches are compared - approximate method based on evaluation of simplified kinetics and a more comprehensive, simulation-based method that utilizes the evaluation of more detailed kinetic models.The analysis is focused on two important types of data processing - correction of experimental results on thermal inertia (phi-factor correction) and estimation of adiabatic time to maximum rate (TMR).The most widely cited method for phi-factor correction is considered and its improvement is proposed to enable more precise prediction of the adiabatic time scale. A procedure for phi-factor correction of pressure response is also proposed. The limitations of this enhanced Fisher's method are discussed by comparison with simulation-based method. All the illustrative materials are based on real examples.As an example of application, the simplified method will be used to predict TMR and its limitations will be discussed. © 2014 Elsevier Ltd.
Singh J.,HEL Ltd.
Chemical Engineer | Year: 2011
The increasing importance of battery testing to make electric cars safe is discussed. The need to develop safe batteries from the outset is a major part of the development effort and safety testing involves adaptation of classic chemical engineering techniques. Tests on an adiabatic reaction calorimeter has found that any heat generated by the exothermic reaction leads to an increase in temperature and, potentially, an exponential rise in the rate of heating in accordance with the Arrhenius law relating reaction rate to temperature. Methods for thermal-abuse testing require the battery to be heated in 5 to 10°C steps until self-heating is detected. The challenge of calibration of the system while testing a battery was overcome by a mathematical model of the heat-loss characteristics of the battery-testing calorimeters (BTC) chamber and this is used for temperature control, without the need for any lengthy calibration.
Singh J.,HEL Ltd
Institution of Chemical Engineers Symposium Series | Year: 2012
This article presents the adaptation of a well known Adiabatic Reaction Calorimeter (ARC*), to test the thermal safety of complete batteries and their components over a wide range of conditions. The resulting device, BTC, conforms to the basic design principles of the ARC* but focuses particularly on of flexibility of operation, allowing a wide range of tests to be performed easily and safely. Typical range of tests that are performed will be described and resulting thermal runaway data from commercial Li-ion batteries presented. A new development in this field, the measurement of heat generated while holding the battery temperature constant, using isothermal calorimeter, will also be discussed as this can be used to generate the basis for thermal management systems for high energy battery applications such as electric vehicles. © 2012 HEL Ltd.
Singh J.,HEL Ltd.
Chemical Engineer | Year: 2011
The push towards electric vehicles means that rechargeable batteries will become a very common feature of the roads in years to come. While the dream of electric cars running on renewably generated power could be some years away, governments are encouraging car drivers to switch to battery power already, and even rewarding them. The large amounts of money being poured into battery research is based very largely around the use of highly reactive chemicals such as lithium, and this has brought to attention the potential safety issues that could make the flammability hazards of petroleum fuels look like mere child's play. If a prototype Li-ion battery is heated beyond its safe temperature (while safely contained inside a steel test cell that can withstand > 200 bar internal pressure, naturally), this will result in an impressive explosion. The need to develop safe batteries from the outset is a major part of the development effort and safety testing involves adaptation of classic chemical engineering techniques. Batteries can lead to problems, either due to internal malfunction within the battery itself, e.g., internal shorting or chemical degradation, or as a result of external problems during legitimate use. The latter includes inadvertently taking the battery to an unsafe temperature and charging it too fast or at too high a voltage. These problems are collectively called battery "abuse", which, in turn, has resulted in "abuse testing" procedures that must be carried out before batteries can be shipped or used in different applications.
Singh J.,HEL Ltd. |
Tee D.,HEL Ltd.
Institution of Chemical Engineers Symposium Series | Year: 2011
Extensive on-going research into the development of large scale batteries for applications such as motor vehicles has raised issues about safety, bearing in mind the potentially explosive and toxic nature of the chemicals involved. This article presents the total redesign and testing of a well known Adiabatic Reaction Calorimeter (ARC*), to test the thermal safety of complete batteries and their components over a wide range of condition, often referred to as "abuse" testing. The resulting device, BTC, conforms to the basic design principles of the ARC* but focuses particularly on the safety aspects and flexibility of operation, allowing a wide range of tests to be performed easily. This paper will describe the important features of the BTC and show that the robust design has been achieved without compromising on accuracy of the results. © Crown Copyright 2011.