Is the control of centrifugal compressor units driven by steam turbines achieved using DCS?

My family has always used DCS, and later we used CCC

All the equipment manufacturers I’ve encountered have refused to use DCS control, claiming that the response time is not fast enough.

If your process places high demands on unit control, then the unit’s control system must meet the following requirements: the hardware itself must be controllable. 1. The speed of the controller – it should be as fast as possible; undeniably, DCS has no advantage in this regard. 2. IO scanning speed – it should be as fast as possible. No matter how fast a CPU is, if it has to deal with IO operations that take more than 200ms per cycle, the CPU’s effectiveness is essentially zero. 3. The speed of data transfer between the IO and CPU generally depends on the IO bus of the control system, which goes without explanation. 4. The issue of multi-threading versus single-threading: For a multi-threaded system, it is best if the scanning and logical processing related to unit control can be handled by a separate thread, free from interference from other programs. After all, what matters most is the speed at which the programs are executed. Speed is the only requirement for hardware. As for why the unit control requires a speed, no explanation is given. There’s also the issue of engineers from DCS manufacturers, which is uncontrollable. It is crucial that they understand the level of expertise required for crew control, on par with that of those who are professionals in this field. Are there mature unit control solutions, not just the programs themselves, but also including algorithms, piping design, etc.? In fact, performance is just one aspect; no matter how good the performance is, it doesn’t necessarily mean that one can do a good job. Technology needs to be constantly updated. Although older technologies are mature, they aren’t necessarily the best. Give new technologies a chance – they will create miracles for you. If all of the above can be achieved, there’s no need to worry about whether to use DCS, ITCC, or PLC. If your process does not require high levels of control for the unit, a Siemens 200 will suffice.

“How should “the process does not require high levels of control for the unit” be understood? Since it’s a centrifugal compression unit driven by steam, the entire plant relies on it~~ Putting aside the process requirements, the manufacturer of the unit should also consider the unit itself. I believe there is no such centrifugal unit that can be stopped or started at will; the energy consumed during starting and stopping, as well as any potential damage to the unit, must be considerable as well. I’ve basically mentioned all the advantages of ITCC over DCS to them, but for company executives who are working with this type of equipment for the first time, as well as equipment manufacturers dealing with such units for the first time, I realize that my ability to persuade them isn’t that strong~~

This post was last edited by Qingqing Zijin_ on 2015-7-29 at 15:16. Not all turbines are equipped with compressors that have high process requirements; for example, the hydrogen compressors used in oil refining have relatively low such requirements – they don’t need to be adjusted at all, as their operating point is far away from the surge line and remains stable. Such units require little adjustment, have a wide range of operation, and thus do not demand high system response times. However, in oil refining as well, the requirements for rich gas compressors are higher. The start-stop function you mentioned is the most basic requirement; if only start-stop control is needed, even the worst-quality hardware will suffice. I don’t know where your control system is used, nor which company designed it. If the operating conditions change frequently, the opening and closing of the surge valve can cause significant fluctuations in the processes downstream. Additionally, if the piping design is not professional or there are errors in the design of the valves or flow control elements, this can lead to delays in the system’s response, thereby increasing the requirements for the control system and control strategies. You can ask the company that handles the control system some questions related to the units; there’s no need to keep asking them about hardware – the only requirement for hardware is speed. You asked what he thinks about speed ； How is a turbine started? ； How is performance adjusted ； How is surge calculated? If he says that all this is determined by the equipment manufacturers, who provide the data, or that the explanations are unclear, then I advise you to be cautious. If the management and the DCS manufacturers are in cahoots, then don’t ask any questions – just do what needs to be done.

I think it would be better if you communicated with the owner’s technical staff; what the management cares about is probably just the cost.

It feels like going back 30 years. Surge control is like a black box; CCC control and similar systems are also not liked by some users. Using DCS to maintain a constant return flow (low flow rate) results in higher energy consumption, but it ensures that the operating conditions remain relatively stable, thus allowing the situation to be managed. For speed control and pumping control, I’ve never seen it implemented using DCS (really, no one dares to do that); back in the day it was the WOODWARD 505/E, and once the configuration files were ready, they would be locked away in a safe. There was once a utility operator who thought he had understood the configuration for 505; during a major maintenance period, he tried to improve his skills on his own, but ended up forgetting how to revert things back to their original state. Once the turbine was restarted, it vibrated noisily and stopped; when it was started again, it stopped once more. Inspection after opening the tank: the shaft is scratched :( That is the main compressor of the combined unit; all the downstream units are dependent on it:curse:. . . The process operation is stable; it can be considered so, but will it actually remain stable? If speed control and pumping control are \"transplanted\" into the DCS, who will provide and verify these algorithms/logic? Is Haoyuan’s device the same as yours? Which of his machines are controlled via DCS? How effective is it? It would be useful for you to conduct actual research and write a report. The personnel in charge of mechanical equipment should be involved throughout the entire process, after all, the machines belong to them. It’s rare to encounter robot homes that use DCS. Then do it this way: the machine provides its own DCS system (along with the device’s brand-specific system), along with a complete control system (similar to ITCC) and a human-machine interface. The contract for the DCS is awarded to the robot manufacturer; in case anything is needed, additional contracts can be signed. All software, hardware, and technical services are provided by the robot manufacturer, and you can then step back from the process. . . The machine is a television; the DCS is just a remote control. Our purpose is to watch TV. The remote control doesn’t work; there are also buttons on the TV itself, which makes it a bit more troublesome. . .

The last edit to this post was made by jiaguoyun on 2015-7-31 at 14:14. Another solution offered by the equipment manufacturer is to use Woodward for speed control and electrical interlocks, while all other components are handled by Siemens PLC400 systems; this setup provides full redundancy. For the shaft systems, Bentley’s 3500 secondary frame can be used. I think in this case the investment cost might not be much lower than that of the previous ITCC system (at least it certainly won’t be cheaper than domestic alternatives). With an ITCC system, the display units can be designed with dual redundancy, while all elements related to interlocks require triple redundancy. Bentley’s secondary frame can be replaced with the 1900 model (the equipment manufacturer states that it lacks phase measurement functions). Our site requirements also dictate the use of explosion-proof components, which helps to reduce costs associated with safety barriers. No matter what system is used to control the unit, the control system must be provided as part of the equipment supplied by the manufacturer – this is something that cannot be compromised under any circumstances. Otherwise, if the performance of regulation and the stability of the operation are not satisfactory, the instruments will bear all the blame~~ For leaders who are not familiar with ITCC and ask whether DCS/PLC can be used, my answer is simply “it doesn’t matter”……@HEJIYUER

This time it’s a system upgrade: low-pressure section uses turbines plus centrifuges, while the high-pressure section uses centrifuges plus reciprocating machines. Therefore, I’m concerned about the load adjustment of the reciprocating machines, as well as whether they might be prone to backflow, which could cause the centrifuges’ surge valves to operate frequently. ~~~ Does @HEJIYUER have any valuable suggestions?

Our centrifuges were also upgraded a few years ago, with the old disc-type instruments replaced by CCCs; some of the parameters related to the compressor are divided into two streams, one going to the CCC and the other to the DCS for monitoring. Control and protection are all handled by the CCC; the DCS merely displays a few key parameters. High precision is required for the control of our compressors, and robust protection measures are essential, as they are after all core equipment. Are you daring to consider just a few cases? ! Even if I were the boss, I wouldn’t have the guts:D.