JPH0555180B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for metering a catalyst used in the FCC process (fluid catalytic cracking process).

[Background of the invention]

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 solely by the above-mentioned regeneration, 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, in a conventional catalyst supply device, a rotor case with a fixed volume is divided into several spaces by a rotor rotating inside the case, and a predetermined amount of catalyst particles is delivered 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, new catalyst is supplied by manually controlling the opening of the valve in the middle of the pipe from the catalyst hopper to the catalyst regenerator while monitoring the catalyst activity in the reactor.
The reality was that it was done intermittently. however,
Precise control of the catalyst supply amount is difficult with such manual valve operation, and from the perspective of maintaining catalyst activity, it is necessary to set an extra target value to account for variations in the catalyst supply amount. Ta. 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 is as much as 40% higher than 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. be 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, air is used as the regeneration gas in the reactor system, particularly in the regenerator, so the introduction of pressurized air into the regenerator is not a hindrance due to 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.

[Summary of the invention]

An object of the present invention is to provide a method for metering and supplying an FCC catalyst which basically employs the above-mentioned method including the use of a metering tank and air pressure feeding, but which enables more accurate weighing and smooth operation. do.

That is, the method for metering and supplying an FCC catalyst according to the present invention is a method for quantitatively supplying an FCC catalyst into a regenerator of an FCC device, and includes the following steps (a), (b), and (c). It is characterized by this.

(b) A step of transferring a certain amount of the FCC catalyst in the catalyst hopper into a measuring tank maintained at the same pressure as in the catalyst hopper; (b) Accurately measuring the amount of FCC catalyst transferred into the measuring tank. In this process, the pressure inside the metering tank is maintained in a pressurized state while the metering tank itself is kept in a floating state, and the pressure inside the metering tank and the pressure downstream of the outlet side of the metering tank are set to the same pressure. (c) A step of transferring the FCC catalyst in the metering tank to the regenerator while maintaining the pressure in the metering tank in a pressurized state.

However, in each of the above steps (a), (b), and (c), the pressurized state is maintained at least higher than the pressure inside the regenerator.

As is clear from the above, in the case of the method of the present invention,
The weight of the metering tank containing the catalyst can be measured by keeping the metering tank floating, e.g.
Since the catalyst can be supported and measured by the weighing device placed in the above locations, it is possible to install a pipe for discharging the catalyst at the bottom of the weighing tank, which allows smooth discharging and weighing of the catalyst by using a relatively small amount of pressurized air. It also becomes possible to improve accuracy. In addition, the floating state of the weighing tank is ensured, and the pressure inside the weighing tank and the downstream side of the outlet side of the weighing tank are kept the same, taking into account leakage from the valve, making it possible to further improve weighing accuracy. Become.

Furthermore, in the method of the invention, the pressure in the metering tank is at least equal to the pressure in the regenerator (usually
Since the pressurized state is maintained at a pressure higher than approximately 2 kg/cm ² ), smooth metering and supply of pressurized air is possible without backflow from the regenerator side.

〔Example〕

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 layout diagram of an apparatus for carrying out the FCC catalyst supply method according to the 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, in a pipe 3 extending from the catalyst hopper 1 to the top of the metering tank 2, a restriction orifice 4, a flow control valve 5, a closing lid 6, and a bellows 7 are inserted 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 control 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 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 apparatus according to the above embodiment, 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, pressurized air will flow through the pressure equalization pipe (although a valve must be inserted into the pressure equalization pipe 18 and 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. Further, in order to maintain a good floating state of the metering tank 2, it is preferable that the bellows 7, 10 and the flexible pipe 14 be provided as close to the metering tank 2 as possible.

Above, one preferred embodiment of the method of metering FCC catalyst 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, it is desirable that the number of scales 12a, 12b, . . . serving as the weighing means be at least three in consideration of the holding stability of the weighing tank 2, but it is also 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 method, it is possible to carry out metering using a metering tank in the catalyst transport path from the catalyst hopper to the reactor system, to ensure a floating state and an equal pressure state in the metering tank, and for example, at three or more locations on the side wall of the metering tank. By placing a scale at the position to support and measure the weight of the weighing tank together with the catalyst content, it becomes possible to smoothly and automatically measure and supply the FCC catalyst. Furthermore, according to the method of the present invention, there is no need to oversupply a catalyst to maintain the necessary reaction activity, so 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 drawings are used to carry out the method of the invention.
FIG. 2 is a schematic layout diagram of each part of the FCC catalyst metering and feeding device. 1...Catalyst hopper, 2...Measuring tank, 5...
Automatic opening/closing valve (flow control valve), 6, 9, 11... Automatic opening/closing 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 method for quantitatively supplying an FCC catalyst into a regenerator of an FCC device, which comprises the following steps (a), (b) and
(c) A method for metering and supplying an FCC catalyst. (b) A step of transferring a certain amount of the FCC catalyst in the catalyst hopper into a measuring tank maintained at the same pressure as in the catalyst hopper; (b) Accurately measuring the amount of FCC catalyst transferred into the measuring tank. In this process, the pressure inside the metering tank is maintained in a pressurized state while the metering tank itself is kept in a floating state, and the pressure inside the metering tank and the pressure downstream of the outlet side of the metering tank are set to the same pressure. (c) A step of transferring the FCC catalyst in the metering tank to the regenerator while maintaining the pressure in the metering tank in a pressurized state. However, in each of the above steps (a), (b), and (c), the pressurized state is maintained at least higher than the pressure inside the regenerator.