Regarding the issue of fuel oil temperature
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The maximum design load of my installation is 125 t/h, but the current processing volume is 140 t/h, with further increases possible. The fuel used in our heating furnace is atmospheric residue oil, which is introduced directly from the fuel tank before it enters the furnace. Since we rely mainly on oil for heating, the temperature of the fuel oil becomes very high (approaching 300°C). I hope experts can provide some good suggestions for technical improvements
300 degrees is too high. Blending with other fuel oil components at lower temperatures can be considered. However, temperature and composition are difficult to control. The furnace temperature is prone to fluctuations. Cooling or heat exchange recovery of this heat source can be considered. Set temperature control. Consider switching to another type of fuel oil
From an economic perspective, it’s a shame to use atmospheric residue as fuel; it would be better to opt for burners suitable for using vacuum residue as fuel. Using vacuum residue as fuel has the following advantages: it has a higher calorific value, allowing for faster heating. An appropriate temperature point can be selected from the heat exchangers through which the vacuum residue passes to draw off the fuel oil stream
You can solve this problem by optimizing the heat exchange process; the normal slag coming out of the normal bottom pump can be divided into two streams and sent directly into the vacuum furnace. One is mixed with the other in the vacuum furnace after heat exchange with the heat exchanger; the fuel oil is drawn out from the outlet of the heat exchanger to lower its temperature
Slag at 300 degrees will catch fire spontaneously once it is released, which is not very reasonable from a safety perspective. Let’s look at the issue from an economic perspective as well.
Can we add a steam generator in the middle? Produces low-pressure steam exclusively....
Our fuel flow rate is only 1–1.5 tons per hour; is the steam generator easy to operate?
In fact, a branch can be taken from the bottom pump and used for the steam generator; since the fuel oil operates in a closed-loop system, any excess amount can be returned to the bottom of the atmospheric tower by adjusting the pressure in the fuel oil circulation line.
It’s really a shame to use atmospheric residue as fuel oil; it’s better to use vacuum residue instead. It should be noted that when using reduced-pressure residue as fuel oil, it seems unnecessary to pass the fuel oil through a heat exchanger for heat exchange! For example, the fuel oil used in our 1 million-ton atmospheric and vacuum distillation unit is taken directly from the outlet pipeline of the bottom suction pump. Think about it: with the outlet temperature of the bottom-reduction pump below 400 degrees, and a fuel flow rate of only 1–1.5 tons per hour, the temperature ahead of the furnace must naturally drop a bit, right? It will be much easier to ignite when the temperature is a bit higher! As for the problem of spontaneous combustion caused by fuel oil leakage, it can be resolved by proper equipment management and enhanced routine inspections. As a side note: we have been using it for over a decade without any instances of fuel oil catching fire on its own.
You can solve this problem by optimizing the heat exchange process. We use a catalytic system that operates at normal pressure with normal slag conditions; the catalyst is applied after passing through a heat exchanger at the bottom of the tower. The fuel oil is drawn out from the exit of the heat exchanger, its temperature is reduced, and then it is sent to the fuel oil tank. Don’t you keep reducing the pressure in your crude oil processing? Shouldn’t there be a constant slag heat exchange and cooling system in the tank area? From here, fuel can be poured into the fuel tank