Armfield

• Understanding the principles of crystallisation
• Understanding crystallisation driving force
• Mass and energy balance
• Batch operation
• Continuous operation (option)
• Evaluation of crystallisation efficiency and crystallisation kinetics
• Study of the effect of different parameters such as agitation rate and cooling rate
• Crystal size distribution

The UOP14-MKII introduces students to the fundamentals of crystallisation using a solution-cooling method. It is a benchtop unit with a clear crystallisation reactor, which enables visualisation of the crystallisation phenomena.

The equipment consists of a jacketed crystallisation vessel provided with temperature control and agitation.

The solution is heated by circulating hot water through the jacket from the hot water vessel in a closed-loop system and the solution is cooled by circulating cold water from mains water supply or a chiller.

At the end of the batch operation, the crystals and mother liquor are collected using the beaker supplied, filtered, washed and then dried in the oven. The dried crystals are then sieved using the set of sieves supplied to analyse the crystal size distribution.

A conductivity sensor is included, which enables crystallisation to be monitored.

Different cooling rates can be investigated by the application of different water flow rates. A needle valve and flow meter are provided to vary the water flow rate quickly and easily to enable investigation of different crystallisation conditions, such as fast and slow cooling rates.

The instruction manual included contains experiments, providing a thorough grounding in the operation of crystallisation systems in the context of unit operations for chemical engineering students.

The equipment is supplied complete with a USB computer interface and data logging software.

The system may also be used in a continuous mode when used with the Armfield Crystallisation Unit UOP14-11 Continuous Feed Accessory.

UOP14-11 Continuous Feed Accessory (optional)

This benchtop item is designed to form a continuous crystallisation system together with the UOP14-MKII. The module can be used for teaching continuous crystallisation and demonstrating its advantages over the batch process. A variable-speed peristaltic feed pump controls the flow rate of the hot solution pumped from the feed tank to the reactor. The feed solution temperature is maintained by the controller linked to two heating elements.

The UOP14-11 is self-contained and can be added at any time to turn a standard batch crystalliser into a continuous system.

UOP14-12 Buchner Filtration Accessory (optional)

The vacuum filtration unit is available as an optional addition that is used to remove the crystals suspended in the solution. The crystals are filtered through the Buchner funnel with the aid of a vacuum. The Buchner funnel is fitted with a round piece of filter paper attached to the Buchner flask where permeate is collected.

The reduced pressure is obtained using an ejector vacuum pump attached to a cold mains water supply.

On opening the armSOFT desktop software, the user is taken to the process screen, which shows a diagram of the equipment/process. The screen shows readings from the equipment, updated in real-time, in engineering units.

This screen will also show any calculated variables and controls that the user may need. Users can navigate to the other parts of the software using the tabs at the bottom of the screen. The Data tab offers a number of options for processing and displaying the data from the equipment. Graphs, results table, bar charts, etc are all available via a second set of tabs to the left of the screen. Users can also select data-filtering options.

Results are saved in a log which can be viewed and manipulated with the armSOFT Results Viewer. Results can be printed or exported to a generic spreadsheet format which can be opened in a wide range of packages for further analysis.

The software also includes facilities for closed loop control. The software uses a PID control algorithm to adjust an output in response to changes in one of the inputs. For example, the pump speed may be varied in order to regulate a flow rate.

For further information on the advanced features of the sophisticated Armfield software visit: www.discoverarmfield.co.uk/data/armsoft

Technical Data UOP14-MKII

• 2l jacketed crystallisation vessel
• Hot water pump
• Flow meter 0.05-3 l/min 
• Three temperature sensors
• Conductivity probe 0-600mS
• Low level liquid sensor
• Cold water supply pressure regulator
• Heater capacity 2kW
• Pressure regulator 0-2 bar

Technical data UOP14-11 (optional)

• Feed pump 0.5-10 l/hr
• 20l feed tank vessel
• Temperature controller
• Temperature sensor

• Software requires a computer running Windows XP or above with a USB port (computer not supplied by Armfield)
• Laboratory oven to dry the crystals sample
• Potassium chloride
• Laboratory balance

• UOP14-11 Continuous Feed Accessory
• UOP14-12 Buchner Filtration Kit

Single phase electrical supply:

Cold water supply: 1 l/min @ 1 bar

• UOP14-MkII Crystallisation Unit
• UOP14-11 Continuous Feed Accessory
• UOP14-12 Buchner Filtration Accessory