JPS6115730B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a catalyst metering device for use in the FCC method (Fluid Catalytic Cracking).

In the FCC method, high-octane gasoline is produced by catalytically cracking diesel oil as a raw material in a fluidized bed using alumina or fine powder such as silica/alumina as a catalyst. The catalyst used in the reaction is introduced into a regenerator, where carbon and other components deposited on contact with air are removed, and then recycled to the reactor again. However, as the reaction continues, the desired catalytic activity cannot be maintained only by regeneration as described above, so it is necessary to supply new catalyst. Naturally, it is desirable to supply this new catalyst at a constant rate (feed rate), but in the past, supplying such a new catalyst at a constant rate was accompanied by great difficulties. .

For example, a conventional catalyst supply device divides a rotor case with a fixed volume into several spaces by a rotor rotating inside the case, and feeds a predetermined amount of catalyst particles according to the rotational speed of the rotor. There is a rotary valve configured to be introduced into and discharged from a rotor case. however,
As this rotary valve continues to be used, accidents frequently occur in which the catalyst gets stuck inside the rotor, where the catalyst should not originally be placed, making it difficult to use the rotary valve continuously.

For this reason, the current situation is that new catalyst is supplied intermittently by manually controlling the opening degree of a valve in the middle of the pipe from the catalyst hopper to the catalyst regenerator while monitoring the catalyst activity in the reactor. Ta. However, with such manual valve operation, it is difficult to precisely control the amount of catalyst supplied, and from the perspective of maintaining catalyst activity, it is necessary to set an extra target value to account for variations in the amount of catalyst supplied. It was hot. According to a trial calculation by the present inventors, the excessive supply amount of the catalyst due to such an excessive setting of the target value increases by as much as 40% over the optimum supply amount.

In view of this current situation, a method has also been proposed in which a metering tank is placed in the flow path from the catalyst hopper to the regenerator, and the amount of catalyst supplied is sequentially measured while new catalyst is intermittently supplied to the reactor system. ing. In this method, the catalyst introduced from the hopper into the metering tank is
The weight, including the weight of the measuring tank, is measured by a scale placed at the bottom of the measuring tank. After weighing, air is supplied from a pipe that has an opening near the bottom of the measuring tank, and the air is supplied to the regenerator through a pipe that opens at the top of the measuring tank. is pumped to.

The method described above has already been adopted as a means of transporting ordinary powder, but as a method of supplying a reaction catalyst, air for pressure feeding gas is introduced into the reactor system. Not generally available. However, in the case of the FCC method, since air is used as a regeneration gas in the reactor system, particularly in the regenerator, the introduction of pressurized air into the regenerator does not interfere with the process characteristics. The above method can be said to skillfully utilize these features of the FCC Act.

However, according to the research conducted by the present inventors, some problems were still found in the above-mentioned method. The biggest one is that a scale is placed below the weighing tank to measure the weight of the weighing tank containing the catalyst, so in order to send the weighed catalyst to the regenerator, air is blown near the bottom of the weighing tank and the top Since the catalyst is pumped out against gravity, a portion of the catalyst remains in the metering tank even after the pumping operation, reducing weighing accuracy.
Furthermore, the amount of air used for pressure feeding also increases, and the disturbance imparted to the reactor system including the regenerator increases accordingly.

An object of the present invention is to provide an FCC catalyst metering and feeding device that basically employs the above-mentioned method that includes the use of a metering tank and air pressure feeding, but is capable of more accurate weighing and smooth operation. do.

That is, the FCC catalyst metering and feeding device of the present invention is configured by connecting a catalyst hopper, a catalyst metering tank disposed below the catalyst hopper, and a regenerator in series through piping in this order; An automatic on-off valve and bellows are inserted between the metering tank and the pipe extending from the bottom of the metering tank to the regenerator, and an automatic on-off valve and bellows are inserted near the bottom of the metering tank to enable vertical displacement of the metering tank. , scales are placed at three or more locations on the side wall of the metering tank to support the metering tank and make it possible to measure the total load of the metering tank and the catalyst inside it, and a flexible pipe is placed in the upper space of the metering tank. This is characterized in that the catalyst is connected to a pressure-feeding air pipe to enable air pressure to be fed to the regenerator after measuring the catalyst.

As is clear from the above, in the case of the device of the present invention,
The weight of the weighing tank containing the catalyst is supported and measured by weighing devices placed at three or more locations on the side wall of the tank, making it possible to install pipes for discharging the catalyst at the bottom of the tank. By using a small amount of pressurized air, it is possible to smoothly discharge the catalyst and improve weighing accuracy. In addition, by installing pressure equalizing piping that ensures the floating state of the weighing tank and also takes into consideration valve leakage, it is possible to further improve weighing accuracy.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail below with reference to the drawings.

The drawing is a schematic diagram of the external layout of an FCC catalyst supply device according to an embodiment of the present invention.

Referring to the drawing, a metering tank 2 is disposed almost directly below a catalyst hopper 1, and a catalyst regenerator (not shown) is located further downstream extending from the bottom piping. Further, a restriction orifice 4, a flow control valve 5, a shutoff valve 6, and a bellows 7 are inserted in the pipe 3 extending from the catalyst hopper 1 to the top of the metering tank 2 in order from upstream to downstream. On the other hand, a shutoff valve 9, a bellows 10, and a shutoff valve 11 are sequentially inserted into a pipe 8 extending downstream from the bottom of the metering tank 2 toward the downstream side. Weighers 12a, 12b, 12c using piezoelectric elements are installed at three locations on the side wall of the weighing tank 2.
are provided at approximately equal intervals (in the figure, for convenience of explanation, they are not necessarily at equal intervals) to support the load of the measuring tank 2. Weighing devices 12a, 12
The outputs from b and 12c are sent to the control device 13,
Based on the output based on the required calculation here, the valves 5, 6,
...is opened and closed. Further, a pressurized air pipe 15 is connected to the upper space of the metering tank 2 via a flexible pipe 14, and this pipe 15 further extends to a pressurized air source (not shown) via a shutoff valve 16. . Furthermore, the shutoff valve 1 of the pressure-feeding air piping 15
6 and downstream of the bellows 10 of the catalyst transfer pipe 8 are the non-return valves 1 that allow air to flow only in a downward direction.
7 is connected by a pressure equalizing pipe 18.

Next, the operation of the above device will be explained along with the configuration of each part as necessary.

At the start of operation, valves 5, 6, 9, 11
is in a closed state, and the valve 16 is normally open at all times. For this reason, the metering tank 2 is, for example,
It is in a pressurized state of 3.5 Kg/cm ² , and air at the same pressure is also supplied to the inside of the raw material hopper 1 . first,
In this state, the weight of the weighing tank 2 itself and the weight of the small amount of catalyst that may remain in it are measured using the scales 12a, 12b, 12c,
The reading is sent to the controller 13, and the zero point adjustment of the catalyst amount is performed. For operation, first, the flow control valve 5
and fully open the shutoff valve 6. As a result, the catalyst 20 in the hopper 1 flows down to the metering tank 2 through the pipe 30 almost by its own weight. The catalyst flow rate at this time is determined by the opening area of the restriction orifice 4. The weight of the catalyst flowing down into the measuring tank 2 is measured by a weighing device 12a using a piezoelectric element,
It is obtained as the total measured value of 12b and 12c. This measured value is sent to the control device 13, and as it approaches the target value, the flow rate control valve 5 is throttled to a half-open state. This flow rate control valve must be suitable for controlling the flow rate of the solid catalyst in a fluidized state; for example, it must be of a type that controls the opening area of the rubber pipe that makes up the inner surface of the valve by compressing it from both sides. is used.

When the measured weight of the catalyst in the metering tank 2 reaches the target value, the flow rate control valve 5 and the shutoff valve 6 are closed. The shutoff valve 6 is of the type described above for the flow control valve 5 and is inferior in terms of airtightness, so it is provided to ensure a closed state.
For example, a ball valve is used.

After confirming the accurate weighing, valves 11 and 9 are sequentially opened to transfer the catalyst in the weighing tank 2 to a regenerator (not shown, internal pressure approximately 2 Kg/cm ² ), and the transfer time elapses within, for example, 30 seconds. The rear valves 9 and 11 are closed. Both valves 9 and 11 are used to air-tightly seal the flow path 8, and for example, valve 6
A ball valve similar to that used is used.

With this, one cycle of catalyst metering is completed.
A predetermined time required by the reaction system (for example, 0 to 30
minutes), then disclose the next metering/feeding operation.

As you can see from the drawing, measuring tank 2
is placed in a floating state by the bellows 7 and 10 and the flexible pipe 14, with the load or stress from other piping parts removed as much as possible. Ensure such a floating state and fill the measuring tank 2.
And the weight of the content catalyst is weighed by weighers 12a, 12b,
It is important that it can be measured by 12c. The bellows 7 and 10 are preferably of a type in which a steel pipe is inserted inside to allow the catalyst to flow, and only the upper end of the pipe is fixed to the upper end flange of the bellows.

Furthermore, in order to improve weighing accuracy, it is also necessary to consider leakage through the valve. This is because, in the apparatus of the present invention, solid catalyst particles flow through the valve, and there is a risk that the airtightness of the valve will be impaired by the solid catalyst particles getting caught. In particular, due to leakage from the valve 11, for example, 0.1 to 0.2 kg/cm ² upstream and downstream of the valve 9.
If such a pressure difference occurs, a catalyst weighing error of about 5 to 10 kg will occur, depending on the area of the measuring tank 2. For this reason, in the embodiment described above, a pressure equalizing pipe 18 is provided to prevent a pressure difference from occurring between the upstream and downstream sides of the valve 9. Such consideration for valve leakage is also required when transferring the catalyst from the raw material hopper 1 to the metering tank 2 using a pressure difference. When the valve 11 is opened to install the pressure equalization pipe 18 described above, the pressurized air will flow through this pressure equalization pipe (although it is necessary to insert the valve into the pressure equalization pipe 18 and open the valve). (This air flow can be blocked by opening and closing during one metering cycle), but since the diameter of the pressure equalizing pipe is small, even if such an air flow occurs, it hardly causes a problem. Still measuring tank 2
In order to maintain a good floating state, bellows 7,
10 and the flexible pipe 14 are preferably provided as close as possible to the metering tank 2.

Above, one preferred embodiment of the FCC catalyst metering device of the present invention has been described. However, within the scope of the present invention, the above embodiments can be implemented with various modifications. For example, the scale 12
It is desirable that the number of a, 12b, etc. is at least three in consideration of the holding stability of the metering tank 2, but it is of course possible to use four or more. In addition to the piezoelectric type, any type of scale can be used as long as it can support the weight of the weighing tank 2 and accurately measure the weight of the catalyst.

As mentioned above, the measurement and measurement of the FCC catalyst of the present invention
According to the supply device, a measuring tank is placed in the catalyst transport path from the catalyst hopper to the reactor system to ensure a floating state and an equal pressure state, and weighing devices are placed at three or more positions on the side wall. By supporting and measuring the weight of the weighing tank along with the catalyst content, it is possible to smoothly and automatically measure and supply the FCC catalyst. Furthermore, since there is no need to oversupply the catalyst to maintain the necessary reaction activity, the amount of catalyst can be saved by about 30%, which has a very large economic effect. Furthermore, since the amount of catalyst supplied can now be controlled to be constant in this way, a great advantage is obtained in that the reaction conditions including the amount of catalyst can be optimized.

[Brief explanation of the drawing]

The drawing is a schematic layout diagram of each part of the FCC catalyst metering and feeding device according to the present invention. 1...Catalyst hopper, 2...Measuring tank, 5...
Automatic on-off valve (flow control valve), 6, 9, 11... Automatic on-off valve (shutoff valve), 7, 10... Bellows, 1
2a, 12b, 12c...Weighing device, 13...Control device, 14...Flexible pipe, 15...Air piping for pressure feeding, 18...Pressure equalization piping.

Claims (1)

[Claims] 1 A catalyst hopper, a catalyst metering tank disposed below the catalyst hopper, and a catalyst regenerator are connected in series in this order by piping, and an automatic on-off valve and an automatic opening/closing valve are connected between the catalyst hopper and the metering tank. A bellows is inserted, and an automatic opening/closing valve and a bellows are inserted near the bottom of the metering tank in the piping extending from the bottom of the metering tank to the regenerator to enable vertical displacement of the metering tank, and a weighing device is installed at three or more locations on the side wall of the metering tank. is placed to support the metering tank and to make it possible to measure the total load of the metering tank and the catalyst inside it.The upper space of the metering tank is connected to a pressurized air piping via a flexible pipe to convey the catalyst after metering. An FCC catalyst metering and feeding device that enables air to be fed under pressure to a regenerator, and further comprises a metering tank upper space and a downstream side of an automatic opening/closing valve at the bottom of the metering tank connected by pressure equalizing piping.