High Pressure Chem-SCAN Operating Manual

Transcription

1 GAS INLET VALVES REACTIVE GAS PRESSURE RELIEF VALVE INERT GAS VENT VENT VALVE REACTOR INLET VALVES PRESSURE TRANSDUCERS REACTORS STIRRER & THERMOWELL HEATING JACKET STIRRER MOTORS High Pressure Chem-SCAN Operating Manual Version 2, 17/01/ Moxon Street, Barnet, Herts EN5 5TS, England Telephone: +44 (0) Fax: +44(0)

2 Contents 1. Introduction Gas Dosing System Uptake Calculation Temperature and Agitation Control The Reactors 5 2. Software Mimic Window Plan Controls Standard Plans Simultaneous Operation: 1 Reaction Step Plan Consecutive Operation Calibration Properties 13 1

3 HP ChemSCAN LICENSE FROM SYMYX Symyx Technologies, Inc ( Symyx ) has granted to HEL a limited license to make, sell, lease, offer for sale or lease, export and import the High Pressure ChemSCAN under U.S. Patent Nos 6,306,658, 6,455,316,6,548,026 and European Patent No: Symyx has additional U.S. and foreign patents pending. Purchasers, Lessees and Users of the High Pressure ChemSCAN do not obtain any license or other rights under or to any patents owned by Symyx. Using the HPCS in and of itself does not impinge upon any Symyx patents. However, if the user s chemistry involves a particular method which happens to be covered by a Symyx (or someone else s) patent then the user may need a license from Symyx (or other patent holder) to perform such method in a country where patent coverage applies. Note that such a caution applies all the time: it is not only or exclusively relevant to the use of the HPCS. 2

4 1. Introduction The high pressure Chem-SCAN system has been designed for the rapid screening of chemical reactions on a 2-10ml scale. The system is completely automated, allowing for unattended operation and data collection as well as real time data interpretation. Chem-SCAN consists of eight reactors that can be run simultaneously or consecutively and can be controlled at the same pressure or at separate pressures. The reactors are heated using an oil-filled jacket that can be raised or lowered into position. Agitation is given by a magnetic stirrer suspended inside each cell; the stirrer motors and coupling are housed underneath the heating jacket. Pressure is applied to the reactors through a series of solenoid valves that operate using a shunting mechanism. The gas is charged through one of two inlet valves and then on to each reactor through a dedicated reactor valve (see Figure One). The pressure in the reactors is continuously monitored using transducers that are located on the top of each reactor. By recording the pressure fluctuations with time in each reactor and interpreting any pressure drop as gas consumption, Chem-SCAN is able to screen reaction rates and catalytic activity during gaseous phase reactions, such as hydrogenations and oxidations. Figure one: layout of Chem-SCAN GAS INLET VALVES REACTIVE GAS PRESSURE RELIEF VALVE INERT GAS VENT VENT VALVE REACTOR INLET VALVES PRESSURE TRANSDUCERS REACTORS STIRRER & THERMOWELL HEATING JACKET STIRRER MOTORS 1.1 Gas Dosing System. The dosing system consists of two gas inlet valves, one for an inert gas and the other for the reactive gas (i.e. hydrogen or oxygen). This allows the user to purge the system with inert gas (to remove residual air) as well as dose the reactive gas. Gas is charged using a 3

5 shunting system. Firstly, the relevant inlet valve opens to allow a volume of gas from the supply into the common feed lines. This valve then closes and the reactor inlet valves open to pressurise the reactors. The inlet valves open and close until the required pressure in each of the reactors has been reached. The pressure control and purge sequences are both automated when using the plan operation mode of the software (section 2). The user can select the frequency at which the reactors are re-pressurised by defining a maximum allowable pressure drop. The system will re-charge gas to the reactor as soon as this margin has been exceeded. This parameter means that Chem-SCAN can operate either to maintain a fixed pressure during a reaction or to run a reaction with a single dose of gas. The length of time that the reactor inlet valves are open or closed can be edited within the calibration parameters of the software. This fine control of the shunt system is an important requirement for running the reactors simultaneously at different pressures. The small bore of the feed restricts the flow of gas to the reactor and when used in combination with a rapid shunt speed, a given reactor can be controlled at a considerably lower pressure than the supply pressure. In practice it is possible to run some reactors at the supply pressure and some reactors at a pressure of up to 20bar lower. 1.2 Uptake Calculation Each reactor has an individually assigned pressure transducer, used to both control and measure the pressure of gas in the reactor. During a reaction in which gas is consumed, the pressure in the reactor will decrease as the volume of gas diminishes. The software uses the ideal gas equation to convert this pressure drop into a volume of gas up taken by the reaction. The amount of gas uptake with time can be displayed graphically as the screening experiment progresses, giving the user a real time assessment of reaction rates and catalytic activity. To perform the calculation the software requires the volume of the whole reactor and the volume of the sample within the reactor. From this the software calculates the dead volume above the sample. The pressure drop across this volume is then used to determine the uptake. The software displays the uptake either as a molar quantity or as a volume in millilitres, calculated from the molar amount. 1.3 Temperature and Agitation Control The Chem-SCAN reactors are all heated from a common oil jacket, fed from a Julabo oil circulator unit. The jacket can be raised to surround the reactors or lowered during cooling using a winch mechanism at the side of the unit. The temperature in the reactors can be controlled either by setting the temperature of the circulating oil or via a PID control loop between the jacket temperature and the temperature of reactor one. 4

6 Reactor agitation is magnetically driven, the speed of stirring being controlled by the software. Each reactor contains an anchor type stirrer with the magnets housed inside the arms of the stirrer (Figure Two). The stirrer motors and magnetic coupling are contained inside and underneath the heating jacket. Stirring will thus only commence when the jacket is raised to accommodate the reactors. The stirrers cannot be individually controlled as Chem-SCAN only allows all stirrers to be on (or off) simultaneously at the same speed. 1.4 The Reactors The actual reactors used on Chem-SCAN are shown schematically on Figure Two. The reactor lids are mounted on a top plate with the reactor body then being screwed into place beneath. C-spanner grooves in the top of the reactor cells allow the user to tighten the reactors. Once tightened, the reactors will be able to hold 100bar pressure. Figure Two: cross sectional schematic of the reactor cells and stirrers Thermowell for thermocouple housing Optional glass insert PTFE stirrer with encapsulated magnets Reactor cell The temperature inside the reactors is measured using K-type thermocouples. The thermocouples are housed in a thermowell inside the stirrer shaft. This avoids the possibility of the stirrers catching the thermocouple if alternatively positioned inside the confined space of the reactor cell. There are two ports available on the lids of the reactors. One is used for the gas feed line, which is also linked to the pressure transducer. The other port is spare and could be used for liquid addition or sampling. A further option is to have glass inserts for the reactors. This could be used for easier cleaning of the reaction vessels and for use with corrosive substances. 5

7 2. Software This section should be read along with the WinISO operating manual. The software controls outlined below are described in more detail within the WinISO manual. 2.1 Mimic Screen The mimic screen (Figure Three) represents a schematic overview of the system. The mimic has two purposes, firstly to activate devices such as the valves or the circulator and secondly to view the current state of these devices. When a valve is active, its colour on the mimic will change from red to green. The stirrer icons will rotate when the stirrers are switched on and the circulator pump will spin and give a reading. Text above the reactor icons gives the current pressure and temperature in the reactors. Figure Three: Chem-SCAN mimic screen Devices and controls available via the mimic screen are as follows: 6

8 Device Description Function Julabo HD oil circulator unit enter a temperature set point Vent vent valve set open or closed Reactive gas reactive gas inlet valve set open or closed Inert gas inert gas inlet valve set open or closed Chemscan shunt reactor inlet valves open or close individual valves or open or close all valves together Stirrer array reactor stirrers activate all stirrers to set speed The devices outlined above can be accessed by selection with the mouse or more readily by using the controls drop-down menu in the centre of the icons panel. It is important to note that whilst valves can be opened and a circulator temperature set, the mimic screen will not support automated control of pressure or reactor temperature. The automated control of devices only occurs via the Plan Control function. The mimic screen for the Chem-SCAN features vector driven graphics. On the right hand side of the icon panel on the window, there are a number of functions that allow the user to scale or move the graphics. The two magnifying glass icons allow enlargement or shrinking of the graphics, whilst the arrows can be used to move the graphics around the window. The fit icon is for automatically scaling the graphics for the size of the window. 2.2 Plan Controls Under plan control, all the devices outlined above and their associated functions can be controlled automatically. The plan controls allow the user to automate pressure and temperature regulation as well as access the uptake calculation feature of the software. The automated controls available are described below. Control R1/Block Temp Pressure 1 to 8: Julabo HD: Valves: Chemscan Shunt: Function Automated temperature control of reactor 1. This reactor is then used to control the temperature of the heating block and thus approximately the temperature of the other reactors. Automated control of reactor pressure. The shunt valves are activated by the software to feed reactive gas to the reactor up to a user defined pressure. The pressure is then maintained according to the defined pressure drop. Alternative method for temperature control by setting a fixed oil temperature and then allowing the reactors to heat up. Vent, reactive gas and inert gas valves can all be set to open or close automatically. Automated control of the reactor inlet valves. The valves can be opened individually or all together. The chemscan shunt control is only used for purging and venting reactors. It should be turned off 7

9 Stirrer Array: during reaction steps as this function cannot be used for pressure control. Automated stirrer speed control. Note that a % output of the power to the motor is set and maintained, not a speed in rpm. The plan edit window, where these controls are edited, is shown in Figure Four. Figure Four: Plan edit window The software has been configured to include logic termination parameters for each step of the experimental plan. This feature allows a greater degree of control over the experiment and enables the user to terminate a step based upon a combination of several conditions. For example, a particular step could be terminated if the time reached 30mins AND the temperature reached 50 C AND the pressure exceeded 10bar. Likewise, a reaction step may be completed if the time exceeded one hour OR if the uptake rate dropped to below 0.02ml / min AND this happened for 5mins. The logic termination also allows the user to define a target step to which the plan will proceed on reaching a certain termination condition. For example, in step one, if the pressure reached 50bar, the plan could go to step four (a vent step say) rather than step two. Likewise, if the pressure did not reach 50bar but the step time of 10mins was exceeded, then the plan would just proceed to step two as normal. 8

10 When running standard plans (see section 2.3), the termination window includes a feature known as the Step Count. This allows the use of repeat steps in the plan and is thus used principally for the purge sequences. The repeat steps greatly simplify the plan. For example, rather than writing say six steps for three gas charges and three vents, the plan could contain just one charge and one vent step with the Step Count and target destination set so that these steps are repeated a desired number of times before the plan proceeds to the next stage of the experiment. 2.3 Standard Plans To simplify writing plans for screening experiments, Chem-SCAN has been supplied with a standard plan for use when running all the reactors simultaneously. The plan can be tailored for an individual experiment by using a Plan Configuration Form. The plan is named 1 Reaction Step and is explained in detail below. To access the plan, load it into WinISO from the default WinISO directory in the C drive of the PC Simultaneous Operation: 1 Reaction Step Plan This plan allows the user to run up to eight reactors simultaneously. The reactor pressures can be identical or individual but all reactors will be at the same temperature. The plan comprises the following eight steps: Step One: Step Two: Step Three: Step Four: Step Five: Step Six: Inert gas purge. Inert gas valve open. Chemscan shunt on and set to open all reactor inlet valves. Stirrers and temperature control on or off. Step terminates on step count OR step time. Vents all reactors. Inert gas valve shut, vent and all reactor inlet valves open; stirring and temperature as previous step. Step terminates on step time. Reactive gas purge. Reactive gas valve and all reactor inlet valves open; temperature control on or off. Step terminates on step count OR step time. Vents all reactors. Reactive gas valve shut, vent and all reactor inlet valves open. Step terminates on step time. Preparation step: reactors are charged to pressure and heated to required temperature. Reactive gas valve open but chemscan shunt now off. Pressure control on reactors 1 to 8 active, pressure maintained to pressure drop setting. Temperature control on or off. Stirrers off. Step terminates on step time AND temperature stability AND reactor pressure OR on step time. Reaction step: stirrers and pressure control activated. Uptake measured. 9

11 Step Seven: Step Eight: Reactive gas valve open, chemscan shunt remains off. Pressure control on all reactors active to maintain set point and pressure drop value. Stirring on and temperature control on or off. Step terminates on step time AND uptake rate OR on step time. Cool down. Reactive gas valve shut, pressure control on all reactors off. Temperature control on or off. Step terminates on temperature OR step time. Depressurise all reactors. Chemscan shunt on to open all reactor inlet valves. Vent valve open. Step terminates on step time. Plan Configuration Form. The plan can be customised very simply by using the Configuration Form. This is accessed via the Configure Plan option under the Plan Menu. The Configuration Form allows the user to input all the desired experimental conditions. The number and nature of the purge sequences can also be set and a separate page is present for entering the sample volumes. The form for the 1ReactionStep plan consists of four pages, each page dedicated to a particular stage of the experiment and is detailed below. Page One: is for setting the inert and reactive gas purge sequences. Set reactor temperature. Set stirrer speed (enter zero for no agitation) Set number of purges (each purge consists of a gas charge step followed by a vent step) Figure 5: page one of the plan configuration form Page Two: is for configuring the reaction step. Set reactor temperature Set stirrer speed Set reactor pressure: yes or no for all reactors at same pressure. If no then click above pressure and enter individual reactor pressures Set termination conditions: enter final uptake rate and reaction time. 10

12 Note: The Preparation step is automatically configured based upon the conditions set for the reaction step (i.e. reactor pressures and temperatures are automatically entered). The reaction step will terminate if the uptake rate is below for user-defined value for a period of 1min. Otherwise the step will terminate on reaction time. Figure 6: page two of the plan configuration form All pressures same (above) or Set individual reactor pressures Page Three: is for defining the conditions of the post reaction step. Set final temperature 11

13 Set final stirrer speed Figure 7: page three of the plan configuration form Page Four: is for entering the sample volumes. Retain the volumes entered for the previous experiment or input a new set of volumes. Figure 8: page four of the plan configuration form After editing the main controls in the plan using the configuration form, it may be desirable to further edit the plan using the plan edit window. For instance, the standard plan contains default settings for step times on the purge steps and a default output file. These would probably require editing to suit the particular set of experimental conditions. In addition, the safety parameters should always be edited prior to running the plan. The user can of course add or delete steps in the standard plan as appropriate Consecutive operation As the chemscan shunt allows the user to open reactors individually, it is possible to write a plan whereby less than eight reactors are run together. Furthermore, plans could be written in which one reactor is screened after another. For example, the user could configure a plan in which each reactor in turn is purged, pressurised and controlled at reaction pressure, just by selecting the appropriate control in the plan and using the correct step sequence and termination parameters. This mode of operation would enable the reactors to be heated to different temperatures or charged to different pressures during each preparation step. 12

14 2.4 Calibration Properties The GenCalibForm, found under the Set Up > Devices / Controls sub menu can be used for viewing and editing calibration properties. For Chem-SCAN the user may wish to edit the speed of the valve operation as well as the volume of the reactors. To edit the valve operating speeds, scroll down to find the Chem-SCAN Shunt entries (see Figure 11). Here, the length of time that the valves are open or closed can be set. This can be changed to introduce fine control to the pressure control. Figure 11: editing the shunt valve settings To change the reactor volumes (see figure 12), scroll down the GenCalibForm to find the Reactor Gas Feed entries. The reactor volumes can be entered here. This would be important if using the optional glass inserts with the reactor cells. Figure 12: editing the reactor volumes 13