Selection of the system
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I have been involved in a large-scale refining and chemical integration project, which includes atmospheric distillation, coking, hydrogen production, sulfur processing and related facilities, as well as various supporting systems. The processing capacity is around 8 million tons per batch. Let’s discuss which brands of DCS and SIS are used there; for unit control, is ITCC or 505 plus 3 taken as 2 used? Can domestic DCS systems such as those made by Zhongkong and HollySys be employed?
DCS from Honeywell is good; the use of 505 plus 3, then taking the best of the two for unit control is a fairly mature approach.
Although I have no experience with large-scale integrated refining projects like yours, I have used the systems from Hilscher and ABICOR BINZEL, and I am aware of some of their application areas. Hilscher is more commonly used in thermal power applications, while ABICOR BINZEL is more frequently utilized in the chemical industry. Both companies have a presence in these two fields, but in large-scale integrated refining projects, their use is likely minimal or non-existent; therefore, I do not recommend them. However, it should be fine to use them in specific areas – selecting the appropriate system based on each company’s strengths in its respective fields can meet the requirements.
I support domestic products. . . . . . . . .
If you’re really worried, for catalysts, you can consider foreign brands. . . . . It is recommended not to set prices too low in tenders, as this will affect quality; don’t assume that domestic products are necessarily inferior. . . . . .
Without domestic products, the selling price of foreign DCS in China is 10 times that in other parts of the world; it has been the same for 15 years. . . . . . . . . . . .
Based on our company’s experience in design, I’d like to say a few words. DCS, SIS: 1. You need to determine the data requirements for this factory based on your financial capabilities, and then the design institute will design the entire factory network. If the requirements are high, the likelihood of using a domestic system is very low. The advantages of imported DCS lie more in the upper-level software such as ODS. If only control at one level is emphasized, the domestically produced Zhejiang University Zhongkong system should be sufficient for oil refining plants. 2. If there are a large number of devices and a high count of points, such as over 20,000 points, DCS and SIS can be considered as separate framework protocols. In this way, the entire plant uses the same DCS system and the same SIS. 3. If financial conditions permit, do not simply win the bid at a low price. Due to low prices, manufacturers are often reluctant to include high-quality equipment in the total cost – items such as operator keyboards, terminal boards, relay boards, and multi-pin cables (referred to as ELCO cables by Honeywell and KS cables by Yokogawa) – and these can only be offered as optional additions. Regarding control systems: Many of the current control system manufacturers use TRICONEX. The reason is naturally the low cost; the overall price of the entire unit is low, making it easy to win bids. In terms of anti-surge performance, CCC is the best but also the most expensive; the 505E model is also good. The scanning speed of the HIMA interlocks is slightly slower than that of TRICONEX, but it is still sufficient for most purposes. But TRICONEX just has a high degree of integration and is hassle-free. You can ask their equipment manufacturers to submit quotes for TRICONEX, CCC+505E+HIMA respectively.
Let’s talk more specifically about the system. 1. For SIS, I personally prefer the 2oo3 voting system. I also remember that TRICONEX has a faster scanning speed compared to HIMA’s H51Q; it seems that HIMA now has METRIX as well, but I’m not sure how it performs. ICS is similar to TRICONEX, but it is more expensive than TRICONEX; in some aspects its performance is also better than that of TRICONEX. 2. For a small DCS system, using an EMERSON system is feasible; for systems with up to 400 I/O points, one DELTA V unit is sufficient (although it is stated that the maximum number of I/O points per system is 750). If a system has a relatively high number of points, Yokogawa and Honeywell are still the better choices. These two are evenly matched. The difference lies in the network structure: Hony has a server-based structure, with historical data and such needing to be stored on those servers. Yokogawa is similar to a peer-to-peer structure. There is only one main engineer station responsible for storing the configuration data, but this data can be transmitted to other ordinary engineer stations, ensuring that in the event the main engineer station fails, another station can take over as the main engineer station to carry out configuration tasks.
From a personal perspective, I tend to support domestic brands. It’s not necessary to set prices at rock bottom; domestic brands are just as good as foreign ones, and if there is any difference, it can be made up for through better service. If the technical requirements are indeed high, appropriate brands should be considered. I have always believed that difficulty determines technology, technology determines price, and price determines quality! Low prices are a crucial factor preventing domestic brands from achieving proper development. Take the water meters I’m familiar with as an example: even a slight difference in precision can result in a price difference of five times or more. There is also a significant difference in price for instruments with the same level of precision. Moreover, even when one manages to develop its own technology, it may still not gain recognition from users. To put it nicely, foreign countries have better technology; to put it bluntly, it’s a form of worshipping foreign things and showing excessive admiration for them, haha. If I complain, please don’t take it personally!
Finally, let’s talk about the unit system. 1. Small units do not require any particularly sophisticated anti-surge control systems; Siemens’ S7-300, S7-400, or AB’s PLCs can be used as alternatives. Or go directly to DCS. If there are certain requirements regarding anti-surge protection for the unit, but only one anti-surge circuit is available, it is possible to consider purchasing CCC’s Series 3 anti-surge controller, which is a highly integrated compact PLC that can be installed in a cabinet. 2. Important units. If it’s a foreign manufacturer of control systems, they probably use TRICONEX. In the case of SHENGU, since it is integrated by SHENGU itself (which is different from foreign units), they may use CCC’s anti-surge system, HIMA’s interlock system, and 505E speed control (or some other speed control method) in their quotes. So when dealing with Shen Gu, you can ask them to provide an additional quote option. In the case of a combination of SHENGU and HANGQI, if there is a requirement for zero-speed cranking, it is essential to clarify during negotiations how zero speed will be fed into the system – one method involves using Bentley’s 50-card interface, another involves using a probe along with a secondary meter to generate a 4-20mA signal, and yet another method involves feeding the signal directly into the system through the probe.