Strata was approached by a global chemical company who was developing new synthesis routes for the manufacture of high value fine chemicals. The brief was to design and construct a specialist high pressure batch reactor facility in which these reactions could be studied at an industrially relevant scale, in a safe working environment, with excellent reproducibility between batches.
The challenge was to develop a unit that would allow a research chemist, with limited process plant experience, to carry out reactions that required the safe handling, accurate dispensing and effective mixing at high pressures and temperatures of the highly toxic, flammable and corrosive process chemicals required to synthesise the new fine chemical products.
Using Strata’s extensive portfolio of pilot plant modules, a cost effective turnkey solution was configured. The initial process and instrumentation diagram (P&ID) was subjected to a detailed design review and a hazard and operability study (HAZOP) to arrive at the final process design for the High Integrity Batch Reactor Pilot Plant.
Using SolidWorks 3D CAD software, the detailed mechanical design for the pilot plant was developed. Specialist vessels were fabricated under the supervision of a Notified Body to ensure compliance with the requirements of the Pressure Equipment Directive 97/23/EC (PED). Two electrical cabinets were designed, the first to house the process control system and the second to house the control gear for the various pumps and motors fitted to the pilot plant. Each of the sub-assemblies were then constructed and tested in our workshop before the pilot plant was erected, integrity and functionally tested in the client’s laboratory facility. Finally process commissioning was completed and a typical trial reaction was undertaken with support from Strata personnel, before the pilot plant was handed over to the client.
The pilot plant comprised:
- A stirred tank reactor featuring: a clamp-ring main body flange with elastomer seal; a 2:1 aspect ratio; magnetically coupled stirrer drive with gas entraining paddle. Working limits: 70barG at 140oC;
- A liquid reactant section designed firstly to allow the solvents and reactants to be safely transferred in the pilot plant holding tanks under an inert gas blanket and then secondly be metered using coriolis mass flow controllers into the reactor;
- A gaseous reactant feed section to allow for highly toxic gaseous reactants to be handled safely and to be dispensed using a coriolis mass flow controller combined with an. electronic pressure controller into the reactor;
- Provisions for safe handling, collection and transfer of the reaction products to storage vessels under an inert blanketing gas.
In order to address the safety and environmental requirements the pilot plant has the following features:
- A dual process alarm safety shutdown system with the first level of process safety alarms being generated by the LabView computer control system and a second independent alarm system using additional process sensors and a Siemen’s PLC running a customised application;
- A custom designed multi chambered extracted enclosure is used to provide a further layer of separation between the hazardous process materials and the research chemists. The extracted enclosure is fabricated in stainless steel for good resistance to corrosion;
- The process vent system is purged with an inert gas and the emissions from all vents – whether voluntary or involuntary – are carefully managed. Before being released to atmosphere, gaseous emissions are passed through appropriate mitigation to ensure that the necessary regulatory requirements are met.
Using a custom designed computerised control system developed in the LabView graphical programming environment, the research chemist is able to plan and set up his experiments. The software interface provides, via an easy to use recipe editor, a mechanism for a research chemist to enter the parameters required for each of the process steps in a clear tabular form. Once developed, these experimental protocols can be saved, reloaded and used as the basis for the development of new experimental protocols. Alternately the research chemist can run the plant manually from the computer screen. In both cases they are able to closely follow the plants response to their instructions using the real-time trend displays. All process control parameters and actions are logged to files which can be used subsequently for in-depth analysis of each experimental reaction.
The High Integrity Batch Reactor Pilot Plant has given the client a facility to carry out batch reactions at high pressures and temperature in many different process configurations including:
- Simple ‘single charge’ of all solvents and reactants before heating the reactor to allow the reaction to proceed;
- Preliminary charge of solvent (and some reactants) before stabilising at reaction conditions (pressure and temperature) followed with stepwise addition of one or more further reaction mixture components during the reaction process;
- Preliminary charge of solvent (and some reactants) before stabilising at reaction conditions (pressure and temperature) followed by addition of the gaseous component of the reaction mixture at a variable mass flow rate in order to maintain a constant pressure in the reactor.
Using this facility has allowed the client to both understand the chemistry of the new synthesis routes to the desired fine chemicals and to generate the engineering data need to carry out preliminary design studies into a full sized production facility.
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