A question about Honeywell’s PKS

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Some time ago, during a technical exchange regarding the pressure swing adsorption process, the manufacturer of this technology raised a rather difficult issue. Below is a detailed description of it. Experts, does anyone know what’s going on here? In the control software package of the PSA unit, not only are the regular control requirements of the system met, but also an automatic arbitrary switching between multiple towers and an adaptive optimization control system, which are essential, are incorporated. To achieve automatic and arbitrary switching between multiple towers as well as adaptive optimization control functions, the control system used for PSA devices is required to possess, in addition to conventional control functions, the following capabilities: 1. The control system must have strong secondary development capabilities ； 2. Advanced programming languages are required, such as languages like BASIC, PASCAL, C, and similar advanced languages ； 3. It must provide the capability to define array variables with at least one dimension ； 4. It must have the capability to write subroutines; the main program should be able to call these subroutines and pass relevant real (actual points defined in the database) and row parameters ； 5. The PSA program utilizes a large number of variables and arrays during its development, requiring the creation of complex mathematical models; as a result, the size of the program is quite large. The main CPU must provide sufficient storage capacity for such high-level language programs, with a minimum storage capacity of 4MB generally being required ； 6. On the human-machine interface, the acquisition rate for all pressure data and timer data is ≤2 seconds. 7. On the human-machine interface, each real-time trend chart shall display no less than 16 data curves simultaneously, with a time resolution of ≤2 seconds, and the real-time trend display duration shall be no less than 40 minutes. 8. On the human-machine interface, each historical trend chart shall display no less than 16 data curves simultaneously, with a time resolution of ≤2 seconds, and the real-time trend display shall cover a period of at least 24 hours. 9. Historical data shall be retained for no less than 6 months. HONEYWELL found that it was not possible to develop the PSA program using PKS’s own software, as the PKS system did not have tools for programming in high-level languages; PKS only allowed programming using CM and SM (function blocks and sequential control blocks). Later, they used a formula management software originally designed for the food industry to carry out the programming, and they managed to complete it after all. However, the volume of code generated was unprecedentedly large. How to maintain it in the future is a major issue. As far as is known, this software is being used for the first time in the country. Its core functionality relies on the traditional function blocks and sequence blocks of the DCS system; since recipe-based software also does not provide advanced programming tools, it only offers functions for managing multiple recipes and scheduling multiple projects, thereby using different combinations of recipes to control the processes. Programs written with this software require at least 20 times more time for major modifications compared to programs written in high-level languages. Even if such a program is developed, maintenance is first and foremost a major problem. In fact, we just went to check this program some time ago, and there are still quite a few issues that require further modifications.