How to prevent coking in the oil and gas pipelines at the inlet of the fractionation tower

1. The temperature at the top of the coke tower should not exceed 420 degrees over an extended period. 2. The amount of steam used for blowing is too large (the gas velocity is too high). 3. The foam layer in the coke tower is too thick; it is necessary to inject an antifoaming agent at the appropriate time. 4. There must be a sufficient safety head height in the coke tower. 5. The quenching oil is too viscous and cannot be completely vaporized. Or the injection method is incorrect, causing the 6 coke towers to experience frequent overpressure. This post was last edited by Hongru on 2009-4-18 13:27]

If it’s a catalytic device, the first thing to focus on is proper design; in the past, the design speed for large oil and gas pipelines was relatively low, but nowadays it’s generally higher； Second, improve the operation of the lift pipe to prevent coking of unvaporized oil; third, ensure proper insulation of the pipelines.

1. Adopt a cold wall design； Increase the flow velocity of oil and gas in large pipelines, and shorten the design length of such pipelines as much as possible, in order to reduce the residence time of oil and gas within them and mitigate the tendency to coking. 2. Elbows with a large radius of curvature are used at the outlet of the settler, while elbows with a small radius of curvature are used at the inlet of the distillation tower, thereby reducing the distance between the elbows and the distillation tower inlet. The 3 pairs of large hot-wall oil and gas pipes need to have enhanced insulation. 4 Strengthen maintenance and coking removal work on large oil and gas pipelines.

1. The line speed of oil and gas pipelines is ensured. 2. The reaction temperature in the riser is moderate. 3. In coking units, the carbon tower should not be flushed frequently

(1) Appropriately increase the line speed. The flow velocity in the RFCCU reaction oil and gas pipelines is 35–45 m/s. (2) Minimize the length of oil and gas pipelines, with a residence time not exceeding 2 seconds. (3) Strengthen insulation to reduce heat loss. Maintain the reaction gas and oil in an overheated gaseous state, paying special attention to insulating pipe fittings such as flanges to reduce coking. (4) Elbows with a large radius of curvature are used at the outlet of the settler, while elbows with a small radius of curvature are used at the inlet of the fractionation tower; N-type compensation through pipe segment bending should be used as little as possible whenever the conditions for thermal compensation are met. (5) Reduce horizontal pipe sections. The horizontal pipeline before entering the fractionation tower should be as short as possible and designed with an appropriate slope leading to the tower inlet, in order to reduce the accumulation of condensate and carbonization. (6) Pay attention to inspection and coking removal. This post was last edited by Refiner on 2009-4-20 11:52.]

I think it should be approached from four aspects: first, increasing the line speed within the limits set by permission restrictions； Second, enhance insulation ； Thirdly, disturbance steam (superheated steam) can be added to the straight section at the inlet of the distillation tower ； Fourth, when the device reduces its load, other means must be used to maintain the line speed.