Process and apparatus for the continuous replacement of the catalyst in a moving-bed unit

A process for continuously replacing a first catalyst of solid particles circulating as a moving bed with particles of a second catalyst in a hydrocarbon treating unit having at least one processing reactor, without the necessity of interrupting treatment occurring in such unit, said process comprising

• withdrawing solid particles, initially composed of the first catalyst, downstream of each reactor relative to the direction of catalyst circulation;
• injecting simultaneously the second catalyst upstream of each reactor at essentially the same volume flow rate as the rate of withdrawal of the first catalyst, with said injecting including injecting a quantity of particles of a third solid substance prior to the injection of the second catalyst, said third substance having a bulk density sufficiently sensibly different from that of the first and second catalysts and said injecting of said third substance being in an amount such that the third substance effectively serves as a marker between the first and second catalysts;
• measuring bulk density continuously or at effective intervals to sense bulk density of the solid particles withdrawn downstream of each reactor sufficiently to detect the occurrence of a change in bulk density, and
• interrupting the withdrawal of the solid particles and the injection of the second catalyst when the bulk density of the withdrawn solid particles has been sensed to be different from that of the first catalyst and becomes equal to that of the marker.

A process for continuously replacing a first catalyst of solid particles circulating as a moving bed with particles of a second catalyst in a hydrocarbon treating unit having at least one processing reactor and treatment occurring in the unit, without interrupting the treatment occurring in such unit, said process comprising

• withdrawing the first catalyst downstream of each reactor relative to the direction of catalyst circulation;
• injecting simultaneously the second catalyst upstream of each reactor at essentially the same volume flow rate as the rate of withdrawal of the first catalyst, with said second catalyst particles having a bulk density sensibly different from that of the first catalyst;
• measuring continuously or at effective intervals the bulk density of the catalyst withdrawn downstream of each reactor sufficiently to detect such sensible change in bulk density, and
• interrupting the withdrawal of the first catalyst and the injection of the second catalyst when the measured bulk density of the withdrawn catalyst after having been measured as different from that of the second catalyst becomes equal to that of the second catalyst.

A process for continuously replacing a first catalyst of solid particles circulating as a moving bed with particles of a second catalyst in a hydrocarbon treating unit having at least one processing reactor and treatment occurring in the unit, without interrupting the treatment occurring in such unit, said process comprising

• withdrawing solid particles, initially composed of the first catalyst, downstream of each reactor relative to the direction of catalyst circulation;
• injecting simultaneously the second catalyst upstream of each reactor at essentially the same volume flow rate as the rate of withdrawal of the first catalyst, with said injecting including injecting a quantity of particles of a third solid substance prior to the injection of the second catalyst, said third substance having a bulk density sufficiently sensibly different from that of the first and second catalysts and said injecting of said third substance being in an amount such that the third substance effectively serves as a marker between the first and second catalysts;
• measuring bulk density continuously or at effective intervals to sense bulk density of the solid particles withdrawn downstream of each reactor sufficiently to detect the occurrence of a change in bulk density, and
• interrupting the withdrawal of the solid particles and the injection of the second catalyst when the bulk density of the withdrawn solid particles has been sensed to be different from that of the first catalyst and becomes equal to that of the marker.