Are all the external heat exchangers in your plant currently generating steam?

The design of external heat exchangers usually has a specific design point, and the range of adjustment is not large, typically around 30%. Therefore, at low processing rates, as long as the bed temperature can be controlled, the external heat exchanger can be shut down. . . Our office currently has external pickup enabled. . . The first few times, since I didn’t fully understand the nuances regarding the load on the external heat exchanger and when to turn it on or off, the tube bundles had to be replaced twice. After learning from those experiences, no further problems occurred. What’s meant by \"learning from experience\" is that one needs to determine whether to operate the external heat exchanger at full capacity, at reduced capacity, or not at all, depending on the processing volume. If the designed capacity of the external heat exchanger does not match the actual processing volume of the system, then it’s necessary to adjust its operation accordingly. . . By the time it is realized that the cost of repairing the external heat exchanger is not equal to the economic value of the steam generated from the recovered heat, it will be too late to regret it. . . Haha. . . :lol

Processing capacity is one aspect, and the properties of the raw materials are another. The residual carbon content of the raw materials we process is around 8. The external heat exchanger operates at nearly full load.

The external heat exchanger of our unit is always on. The current processing capacity is 150 tons per hour, with about 3 units of raw material residue. It can produce about 35 tons of steam per hour, with relatively stable operation. According to changes in the properties of the raw materials, adjust the opening degree of the external intake to change the heat absorbed by it, thereby ensuring stable temperatures in the secondary stage.

In simple terms, it’s a matter of coking. When the level of coking is 5%, it’s possible to maintain thermal balance without removing heat. However, when the amount of coking becomes too high (due to excessive depth, large feed rates, heavy feed materials, high recycling ratios, or high activity), it becomes necessary to remove excess heat in order to maintain thermal balance, provided that there is the capability to do so. Although there is an economic crisis and the volume of processing has decreased a bit, we are still able to carry on with slag mixing, and external heat extraction allows us to produce around 15 tons per hour of steam at 3.5 MPA.

We use heavy oil catalysis; the heat exchanger is basically operating at full capacity to generate steam, producing 140 tons of steam per hour. If it is shut down, the plant will likely have to cease operations as well.

The external heat exchanger is originally used to regulate the bed temperature. If the oil pressure is high, we use our device; if it’s low, we manually turn it off. The oil level has been low these past few days, and on top of that it’s raining; the poor boilers are completely overwhelmed. :lol

The external heat exchanger is primarily used to regulate the bed temperature. When there is a high amount of coke formation, it is necessary to use this heat exchanger. However, if the processing capacity of the unit is low and the bed temperature is low, the external heat exchanger can be omitted; in such cases, it is important to carry out regular maintenance to maintain an appropriate level of hot water circulation, thereby preventing the tube bundle from becoming deformed due to catalyst leakage caused by faulty control valves. During the first startup of our unit’s DCC plant, since operations were carried out according to the DCC II procedures and coke formation was low, the external heat exchanger was kept in use throughout. But during maintenance, it was found that the tube bundle had become deformed.

It’s still producing steam – what’s the situation with such a low processing capacity on the part of the poster? Can it be operated smoothly?