Cookin' Up a Fine Elixir

End-users, system integrators and suppliers are implementing ISA-88-based solutions in many new and unexpected applications

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Similarly, Dr. Carl Lawton, of the University of Massachusetts Lowell’s Bio Manufacturing Center (BMC), reports that his facility is optimizing its pilot plant’s new batch bioreactor with help from Invensys Foxboro’s InFusion solution. The center received $50 million in initial state and other financing and is expected to receive hundred of millions more as its missions and projects multiply as part of the Massachusetts Life Sciences Initiative.

“There hasn’t been a lot of process control in biopharmaceutical manufacturing yet, and so the joke is that potato chip makers are more advanced than us,” says Lawton. 

Lawton adds that one overall effort in his field is to get away from using the typical 1,000-gallon, stainless-steel vessels to focus on short-run, pilot production that can confirm proper process development and resolve commercial production issues. This allows developers to reduce costs of their initial engineering runs, and conduct more of them. For example, Lawton BMC has been working with Nova Biomedical, Waltham, Mass., on a joint glucose feedback control system. Though also still in the pilot stage, this project could improve several biopharmaceutical manufacturing processes.

Big time batch

Figure 3
Air Products’ plant in Wichita, Kan., uses Siemens E&A’s PCS 7 and Simatic Batch software to improve product consistency, reduce downtime and maintenance costs, and gather historical data.
In addition, InFusion is being used to automate the IT functions on a 190-liter bioreactor that Wyeth, Madison, N.J., recently donated to BMC. Control capabilities required on the reactor include an accurate process control system that can be validated; flexible and scalable functions that can be modified with minimal cost; compliance with FDA 21 CFR Part 11 and ISA-88; and supervisory control and data acquisition (SCADA) functions.

“We can use the system we’re building now with InFusion to make good laboratory practices (GLP) materials, and then move into good manufacturing practice (GMP) areas,” adds Lawton.

In addition, AstraZeneca recently rebuilt its 20-year-old beta blocker pharmaceutical batch plant in Sodertalje, Sweden, and implemented a batch protocol-focused system controlled by ABB’s System 800xA and SattLine system based on eight System 800xA servers (Figure 2). AstraZeneca’s new automation system includes batch and information management modules incorporating functions for batch production, modelling, execution, batch control and reporting for traceability and GMP-based validation.

“From here we can control the entire plant,” says operator Ann Lindholtz, from AstraZeneca’s control room, where she uses her signature to approve increasing pressure in a vessel to 265 kPa by opening a valve. This continues a pharmaceutical process according to its recipe in the application’s electronic batch protocol.” Batch not only rocks—it rules.

Check our Batch Manufacturing Guide, click here.

Tips for Engineering a Batch Project

The following recommendations for successfully implementing a batch project are from “Tips and Tricks to Applying S88 Batch Standards to Chemical Plant Batch Systems” by P. Hunter Vegas of Avid Solutions Inc. in Winston Salem, N.C. 

Do not try to learn batch on the fly. Decisions you make now will haunt you for the life of the system. Find someone who has successfully programmed similar systems, and check beyond initial references with whoever is maintaining the batch system your candidate installed. If the project budget is tight, consider hiring your candidate for a few days to help lay out the general recipe structure and phase definitions.

Select a few products representative of the required recipes. Lay them out using sequential function charts (SFCs), and note the number of parallel phases. Also, remember the puzzle-piece phase technique. Does it make sense to split up a task into smaller pieces? Once the basic phase function is determined, identify the required phase parameters. If a phase needs different parameters in different recipes, consider creating one phase that uses all the phase parameters and dummy out the unused ones. 

If setpoint ramping or stepping is required for reactor heating/cooling, consider creating a reactor profile phase (RPP), rather than making a heating/cooling phase with built-in ramping. RPP runs parallel to the heating/cooling phase and is mode synchronized with it. As RPP runs, it writes setpoints to the heating/cooling phase. This lets developers use the same heating/cooling phases for all recipes.

A recipe often requires verification that raw materials are available before starting the charge phase. Rather than programming this function into your charge phases, create a weight-check phase with a minimum and maximum allowable range for a weight or level. If the reading of interest isn’t in range, then the phase goes to hold. 

Now the phases can be programmed with minimal rework. Issues to consider at this stage include:

  • Consider remote versus local mode for valves and pumps. Nearly all control systems have Remote/Local modes—or sometimes Manual/Auto and even Cascade modes—for valves and pumps. Generally, the valve orpump is controlled by the computer in one mode and by the operator in another. Sometimes the valve or pump has a mode, where it can be controlled by either. Some designers require operators to place each device in Remote or Cascade mode, or the batch won’t function. Others allow the computer or operator to move valves. It’s crucial to handle the modes cleanly in programming. If all the valves and pumps must be in Remote/Cascade mode, check this before starting the phase. Force the phase to hold if a required valve/pump mode is incorrect. If the control system allows computer or operator control, then the pump and valve status should be monitored, so the phase will go to Hold if a valve or pump changes state unexpectedly. 
  • Reset valves on every restart. A typical material charge phase will allocate the header, reset the totalizer, close all valves on the header, open valves as necessary on the header, start the pump and begin monitoring the totalizer, valve positions and pump status. If the phase goes to Hold, then on restart, the phase should follow the same sequence as the initial start without allocating the header and resetting the totalizer. Instead of programming the restart sequence in the “Restart Logic” area of the block, include a Restart bypass on the header allocation and totalizer reset and rerun the phase “Run” logic from the beginning. That way there’s only one logic set to maintain in the phase.
  • Delay reading and writing report parameters. Many phases write report parameters at the end of the phase to track actual charge amounts versus setpoints, etc. If the phase does this, it’s best to delay a few seconds after the charge is complete before obtaining the final totalizer value. This will capture any “dribble flow.”
  • Add lots of phase messaging. There’s nothing more frustrating than a batch control system that lacks phase messaging or has useless phase messages, such as “Phase on Hold.” It doesn’t take much effort to add lines in the phase to indicate what’s going on as the logic proceeds, and it’s critical that the phase logic tells the operator why it went to hold. You’ll get fewer 2:00 a.m. calls if you give the operator tools to troubleshoot and correct his problems!
  • Keep phase programming simple! A large, unwieldy phase may be a logic masterpiece, but make sure it’s not a nightmare to troubleshoot and modify.
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