Utilization of heat from catalytic slurry

The accident rate in catalytic units is too high; heat exchange between the slurry and other units will inevitably increase the frequency of accidents in both types of units. In my opinion, given the high thermal value of the slurry, it is better to generate steam, as this is effective in reducing the energy consumption in catalytic processes.

Steam can be generated, and this steam can then be made full use of to avoid interference with other devices

Moreover, the catalytic slurry exchanges heat with other units, depending on the layout of the units. The design institute once designed for us a line coming from atmospheric and vacuum distillation for heat exchange with oil slurry. On the surface, it seems like energy is being utilized efficiently, but in reality the pipeline is over a thousand meters long and also requires heat tracing, making it completely uneconomical; therefore it was simply cancelled.

The most classic approach is to combine it with atmospheric and vacuum distillation, which can replace part of the fuel, resulting in good economic benefits. It should be noted that catalytic steam is generated by the heat from catalytic charring, and the production of steam is essentially a waste. The best approach for thermal integration is to transport the vacuum distillate bottom oil via pipelines to the catalytic unit for heat exchange with the catalytic slurry. The flow path of the catalytic slurry is modified such that after being drawn off, it first exchanges heat with the vacuum distillate bottom oil, then with the feedstock, and finally returns to the tower after passing through an evaporator. The evaporator is retained as a means of regulation for returning to the tower, making control easier. Due to the large distances between the units in Chinese refineries, heat losses resulting from the long-distance transmission of high-temperature heat are relatively significant; therefore, it is necessary to enhance insulation, and the insulation work must be carried out rigorously to ensure its effectiveness. If calculations show that this combination of heat sources is not economical (good insulation usually makes it quite economical), it is possible to consider generating medium-pressure steam (3.5 MPa); generating low-pressure steam would be the least economical option. Some personal experience.

Our device’s oil slurry is primarily used for two purposes: exchanging heat with the raw material to raise its preheating temperature, and exchanging heat with deoxygenated water to produce saturated steam, which is then superheated to generate 3.5 MPa steam

We exchange heat with the crude bottom oil from the atmospheric and vacuum distillation units; thermal integration yields better benefits, but it requires a short distance between the two units.

Well, some distillation units and catalytic units are located together, allowing for thermal integration; however, in many cases the catalytic units and distillation units are far apart from each other, which makes such integration impractical. Additionally, there are safety concerns – the slurry system is the part most prone to problems. If there are issues with the slurry system in a catalytic unit, then the distillation unit loses its heat source, which has wide-ranging consequences! Overall, it is more reasonable to use steam. Of course, if a leak in the tube bundle of the slurry steam generator is detected, the steam pipeline system must be shut down promptly; otherwise, the consequences can be severe.

I have a question: Is medium-pressure steam or low-pressure steam generated, and how is the pressure of this steam controlled?