The pharmaceutical industry represents a different set of challenges for process control than the bulk chemicals and plastics sectors. Instead of gargantuan plants where large reactors make tonnes upon tonnes of relatively low-value products on a continuous basis, a pharmaceutical plant is smaller, with products produced in batches. But while each batch may only be a couple of hundred or even tens of kilos, the complex chemicals produced, active ingredients for drugs, are likely to be extremely valuable.
For the process-control engineer, this is a tricky prospect. In a continuous reactor, the conditions — temperature, pressure, concentration and so on — must be kept constant, so the task of the control system is to keep everything within certain set-points. But in a batch reaction, the system never reaches this steady state: everything continually changes. Moreover, a pharmaceutical plant has to be flexible; day to day, a single reactor may produce a range of different products.
To handle this sort of situation,Honeywell
has devised a new version of its Experian Process Knowledge System specifically for small manufacturing sites. Aimed at pharmaceutical and speciality chemicals operations, as well as other batch-process users such as in the food, beverage and toiletry industries, the new Experian LS system is claimed to save up to $20,000 (£14,500) in support costs.
In general, small batch systems are controlled by programmable logic controllers (PLCs), which are arrays of computerised electronic switches that are configured to handle relatively small numbers of inputs and outputs from sensors, valves and so on. Larger plants are controlled by distributed control systems (DCSs), which are capable of many more inputs and outputs and incorporate more processing power, allowing complex analysis of the process variables to give the operators better control over the process. But DCSs tend to be too large and expensive to be practical for smaller plants.
Over recent years, increasing processing power and falling prices have brought the abilities of PLCs and DCSs closer together, but there is still a gap, which Honeywell is aiming to fill with the Experian LS. 'Many applications in the food and beverage, speciality chemical, pharmaceutical and life sciences industries would benefit from the functionality of a DCS, but the installed base has been limited because of the perceptions of lack of scalability, great complexity and high costs,' said Craig Resnick, an analyst with market researcher ARC Advisory Service. 'Experian LS appears to address these issues by being designed to be a "DCS for the masses" — one that can be specified, purchased, installed and maintained in a scalable fashion by organisations that have not utilised DCSs in the past.'
The scalability is a vital part of the thinking behind the system. Experian can operate on anything from a single PC and controller, to multiple stations around a larger site, Honeywell claims. Systems can be configured using a simple drag-and-drop interface, with batch-control functionality built-in. Various control algorithms are built into the system, so do not have to be custom-coded; displays are also pre-configured.
For the operator, Experian LS allows the configuration of automation to be changed without stopping production, while the progress of the process can be displayed in terms of the run time and the status of the process sequence. This, Honeywell claims, reduces the engineering effort needed to configure the system, speeds up changeovers from one recipe to another and helps users to modify the production levels of their processes to meet market demands.
The development was a direct response to customer demands, according to Harsh Chitale, who is in charge of Honeywell's strategy. 'For many years, smaller manufacturers faced a dilemma,' Chitale explained. 'They needed to quickly adapt their processes to market changes, but doing so could reduce the system reliability and increase lifecycle costs.' Resnick pointed out that operators face other pressures as well, particularly in the pharma and life sciences sectors, and noted the 'unprecedented pressures to cut costs while simultaneously meeting increased regulations and sustainability objectives', all of which depend strongly on close control of the inputs and the conditions of their processes.
'Smaller manufacturers tell us they need DCS functionality, such as the system reliability and flexibility that PLCs can't offer, but many leading DCSs are just too big for their operations,' Chitale added. 'Experian LS offers the best of both worlds — it provides agility to respond to product mix changes and offers advanced optimisation and batch technology found in larger DCSs.'
Pharmaceuticals seems to be bucking the trend of the credit crunch, with plant expansions and diversification into new technology areas. Bristol-Myers Squibb, for example, is building a $750m (£540m) facility in Devens, Massachusetts, to produce drug ingredients from cell cultures and has awarded the automation contract to Emerson.
Far from the small set-ups targeted by Honeywell, the BMS plant will have 120,000 litres of bioreactor capacity and the control system is at a similar scale. Using the Syncade Smart Operations Management software on Emerson's trademark DeltaV digital automation, the system will handle recipe management, material tracking, data capture and exceptions reporting, as well as automating production equipment and weighing and dispensing.
The Syncade system integrates recipe design and execution for manual and automatic processes. It also automatically generates electronic batch records, including electronic signatures, which are essential for regulatory compliance. According to Emerson, it will help the company respond quickly to changes in product demand and will also speed up technology transfer from research and development into production.