JP2593076B2 - Industrial process control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a power recovery process using a turbine provided in a fluid catalytic cracking device at an oil refinery or a blast furnace exhaust gas treatment device at an iron ore smelter, or a gas compressor. The present invention relates to a method for controlling an industrial process such as a gas transfer process.

[Prior Art] A general control method will be described.

For a very general control system, one control variable has one operating terminal to control it. This is shown in FIG. 6 (A).

In rare cases, one control variable may be controlled by two operation terminals. Fig. 6 (B)
However, this is merely a modification, and for the sake of control (for example, when the flow path is divided or control is required even in a low flow rate region), only two operation ends are provided.

That is, the operation ends A and B have continuity (this continuity is important), and the control system uses the operation end B if the operation end A cannot be controlled.

The case to which the present invention is applied is a very special control system.

This is a case in which two control terminals p and q have two operating terminals A and B, but they are not independent and the operating terminals A and B are not independent.
Can control both control variables p and q. However,
If different control signals come to one operation terminal at the same time,
Since control is not possible, this signal is
The control system is selected by the selector. (In this case, a low selector for selecting a low value is added, and the smaller one of the control systems px and qx can operate the operation terminal A.) Also, the operation terminal B controls only the control variable p. You can do it. This is illustrated in the same manner as in the previous section.
The result is as shown in FIG.

The control problem will be specifically described to make it easier to understand.

For example, suppose that the operation terminal A controls the control variable q, and the control amount is 40%. At the same time, it is assumed that the control variable p is controlled by the operation terminal B, and the control amount is 60%.

Now, the control amounts px and qx are determined by the deviation between the set value and the measured value of the controller, and the magnitude and the sustainability are adjusted to those suitable for the process by the proportional band, the integration time, and the differentiation time. ing. Therefore, the operation ends A and B are delicately controlled in response to the process fluctuation, and the fluctuation is absorbed.

As the above-mentioned industrial process, for example, JP-A-56-88920
In a fluid catalytic cracking device as described in
A power recovery process includes a regeneration tower and a turbine as a gas supply source. In this power recovery process, the control variable p is the gas supply pressure, the control variable q is the turbine load, the operation end A is an inlet valve provided in the turbine inlet flow path, and the operation end B is provided in the turbine bypass flow path. (1) The operation end A is driven by a lower control amount of the gas supply pressure control amount px output by the pressure controller and the turbine load control amount qx output by the load controller, and 2) The operation end A operates under the condition that the control amount px is in the range of 0% to 50%, and the operation end B operates under the condition that the control amount px is within the range of 50% to 100% (the operation end). Switching level p ₀ is 50%
Example).

The operating end A is fully closed when the output px of the pressure regulator changes from 0% to 50%, and is fully open. The operating end B is fully closed when the output px of the pressure regulator changes from 50% to 100%. It becomes fully open from.

[Problems to be Solved by the Invention] By the way, in the control method of the conventional industrial process, for example, the power circuit process will be described as an example. And controlling the gas supply pressure p at the operation end B, and controlling the gas supply pressure p at the operation end A to control the turbine load q.
Is one of two states, which are fluctuating within the set range of the allowable load.

In the above state, the gas supply pressure p is controlled at the operation end B, the output px of the pressure regulator is 50% or more, and the turbine load q is set at the operation end A. It is controlled and the output qx of the load regulator is less than 50%. Under this condition, when the exhaust gas from the regenerator is reduced due to a process change, if the pressure px cannot be controlled even if the output px of the pressure regulator is reduced to 50% and the operation terminal B is fully closed, the operation terminal A is immediately turned off. Pressure must be controlled by squeezing. However, in order to control the pressure at the operating end A, the output px of the pressure regulator must be lower than the output qx of the load regulator. In the conventional control method, the above px is reduced by 50%. It takes a time delay to change the value to less than or equal to the value of qx, and as a result, the gas supply pressure is greatly reduced. That is, the operation end A is
It is controlled around 40% by the control amount qx as shown in the figure.
At this time, the operation end B was controlled at around 60% by the control amount px. However, suppose the process fluctuates and the pressure drops. First, the controller lowers the control amount px as a control operation for maintaining the set value. As a result, the operation end B starts to move in the closing direction, but the pressure does not recover even if the operation end B is fully closed. Therefore, further reduce the control amount,
The operation end A is to be closed. However, since the operation end A is already in the 40% state, the operation end A is kept until the control amount decreases.
Cannot be moved (time delay). That is, continuity is not maintained as described above. In this case, when the control amount is between 40% and 50%, the control variable px becomes an uncontrollable region. During this time, the process is expected to fluctuate greatly.

(Problems in state (2)) In the above state, the gas supply pressure p is controlled at the operation end A, the output px of the pressure regulator is 50% or less, and the turbine load q is the allowable load. It fluctuates within the range. Under this condition, when the exhaust gas from the regeneration tower suddenly increases due to a process change, the output px of the pressure regulator increases and the operating end A is opened, but the turbine load q also increases. Reaches a permissible set value, the output qx of the load controller drives the operation terminal A prior to the output px of the pressure regulator, and the operation terminal A is maintained at a constant low opening. At this time, the operating end B must be opened immediately to control the pressure. However, in order to control the pressure by opening the operation terminal B, the output of the pressure regulator is required.
px must be set to 50% or more, and in the conventional control method, it takes time to change the above-mentioned px from the state where qx was prioritized to 50% or more, resulting in a large increase in gas supply pressure. Would lead to a significant rise. That is, it is assumed that the operation terminal A is controlled by the control amount px and is 30% (the control amount of the control variable q is 40%). Thereafter, the pressure gradually increases and the operation end A opens, but when the pressure reaches 40%, the control right of the operation end is transferred to the control amount qx (the smaller one is selected). In this case, it is necessary to control the operating end B. However, as described above, the operating ends A and B cannot be operated between 40% and 50% (time delay), and an uncontrollable area is created. Will be. Further, when the load of the generator or the like is interrupted in the above state, the output qx of the load adjuster is forcibly reduced to 0% by the operation of the safety protection mechanism.
And the operation end A is fully closed. In this case, the pressure regulator must immediately open the operating end B to control the pressure. However, also in this case, as described above, there is a time delay in increasing the output px of the pressure regulator to 50% or more, and as a result, a large increase in gas supply pressure is caused.

That is, in the control method of the conventional factory process, there is a time delay in switching between the control by the operation terminal A and the control by the operation terminal B in accordance with the process change, and the control variable p is quickly and highly controlled. Cannot control to accuracy.

An object of the present invention is to enable the control by the operation terminal A and the control by the operation terminal B to be immediately switched to each other in response to a process change, and to enable the control variable p to be controlled quickly and with high accuracy.

[Means for Solving the Problems] The present invention has two control variables p and q as control targets, and has an operation terminal A for controlling both control variables p and q.
An operation terminal B for controlling only the control variable p is provided, and the operation terminal A is driven by a lower control amount of the control amount px for the control variable p and the control amount qx for the control variable q, and control amount px is controls the control variable p at only operating end a when in the predetermined low-level side than the operation terminal switching level p ₀ for variable p, the control amount px for control variables p in advance When the operation switching level p ₀ is higher than the operation switching level p ₀ , the operation terminal B
In the industrial process control method for controlling the control variable p, the control variable px for the control variable p and the control variable qx for the control variable q are always compared, If the control amount px is below the operating end switching level p ₀ is the controlled variable px forcibly changed to control the amount qx below, so as to control the variable p can be immediately controlled by the operation terminal a, the operating end Under the operation state of only A, the control amount px is relatively controlled by the control amount qx.
When exceeded, change in the control amount px force the operation end switch level p ₀ or more, which was to be controlled control variables p immediately at the operating end B.

[Operation] The present invention is implemented by a control circuit as shown in FIG. 1 is an industrial process, 2 is a first regulator, which outputs a control variable px for a control variable p, and 3 is a second regulator, which outputs a control variable qx for a control variable q. Reference numeral 4 denotes a comparison operation unit which compares the control amount px with the control amount qx and outputs a lower control amount px or qx as a control amount for the operation terminal A.

The normal operation state of the industrial process to which the present invention is applied is a state in which the control variable q is controlled at the operation end A and a control variable p is controlled at the operation end B, p is controlled, and the control variable q becomes one of two states within a set allowable range.

In the above state, the control variable p is controlled by the operation terminal B, the output px of the first controller is at or above the operation terminal switching level p ₀ , the control variable q is controlled by the operation terminal A, output qx 2 regulator has a less controlled element switching level p _0.
Under this condition, the output px of the first controller is changed due to a process change.
Is less than the operating end switching level p ₀ , the operating end A must immediately control the control variable p. However, in the present invention, the control amount px is forcibly changed to be equal to or less than the control amount qx according to the mode so that the control amount px jumps over the gap region C shown in FIG. 2 (see the solid line arrow in FIG. 2). As a result, the control variable p can be immediately controlled at the operation terminal A without a time delay.

In the above state, the control variable p is controlled by the operation terminal A, and the internal force px of the first regulator is controlled by the operation terminal switching level p _0.
Here, the control variable q fluctuates within an allowable range. In this state, if the output px of the first controller relatively exceeds the output qx of the second controller due to a process change, the control variable p must be immediately controlled at the operation terminal B. However, according to the present invention, the control amount px is forcibly set to the operating end switching level p ₀ or more by the mode so that the control amount px jumps over the gap region C shown in FIG. 2 (see the broken line arrow in FIG. 2). Since it is changed, the control variable p can be immediately controlled by the operation terminal B without time delay.

That is, according to the present invention, the control by the operation terminal A and the control by the operation terminal B can be immediately switched to each other with respect to the process change, and the control variable p can be quickly and accurately controlled.

[Embodiment] FIG. 3 is a control circuit diagram showing a power recovery process according to a first embodiment of the present invention, and FIG. 4 is a diagram showing a relationship between operation amounts of operation terminals A and B and a control amount px. is there.

In the power recovery process 10, in a fluidized catalytic cracking apparatus, part or all of exhaust gas of a regeneration tower 11 as a gas supply source is discharged through a turbine 12, and the remaining exhaust gas is bypassed to the turbine 12. For example, a generator 13 as a turbine load is directly connected to the turbine 12. In the power recovery process 10, the control variable p of the present invention is used.
Is a gas supply pressure (may be a pressure difference between a regeneration tower and a reaction tower), a control variable q is a turbine load, an operation end A is an inlet valve provided in a turbine inlet flow path, and an operation end B is a bypass provided in a turbine bypass flow path. (1) The operating end A is a gas supply pressure control amount px output by the pressure controller 14 and a turbine load control amount qx output by the load controller 15
Are compared with each other in the comparison computing unit 16 and are driven with a lower control amount than the comparison computing unit 16 outputs. actuated, the operating end B control amount px is operated in a state where the range of 50% to 100% (operating end switching level p ₀ 50%
Example).

That is, when the pressure in the regeneration tower 11 increases in the above process, the operation end A is first opened to control the pressure. When the pressure cannot be controlled only by the operation end A and the pressure still rises, the operation end B is subsequently opened to control the pressure. When the output px of the pressure regulator 14 changes from 0% to 50%, the operation end A is fully closed to fully open, and the operation end B is when the output px of the pressure regulator 14 is 50% to 10%.
When it changes to 0%, it changes from fully closed to fully open. Load controller 15
The operating end A is operated to keep the turbine load (or turbine rotation speed) within an allowable range. In addition, 17 is a pressure detector and 18 is a load detector.

Thus, the power recovery process 10 includes a pressure regulator 14
Takes the output qx of the load controller 15, and controls the control amount px and the control amount.
qx is constantly compared with the control amount px
Is less than the operation end switching level p ₀ (50%), the control amount px is forcibly changed to the control amount qx or less so that the gas supply pressure p can be immediately controlled at the operation end A, When the control amount px relatively exceeds the control amount qx under the operation state of only the operation end A, the control amount px is forcibly changed to the operation end switching level p _0.
(50%) or more so that the gas supply pressure p can be immediately controlled at the operation end B.

Hereinafter, the operation of the power recovery process 10 having the above configuration will be described.

The normal operation state of the power recovery process 10 includes a state in which the turbine load q is controlled at the operation end A, a gas supply pressure p is controlled at the operation end B, and a gas supply pressure p at the operation end A. And the turbine load q
Is one of two states, which are fluctuating within the set range of the allowable load.

In the above state, the gas supply pressure p is controlled at the operation end B, and the output px of the pressure regulator 14 is 50% or more.
The turbine load q is controlled by the operation terminal A, and the load controller 15
Is less than 50%. Under this condition, if the exhaust gas of the regeneration tower 11 decreases due to a process change, and if the output qx of the pressure regulator 14 is reduced to 50% and the operation end B cannot be fully controlled even when the operation end B is fully closed, the operation end immediately The pressure must be controlled by restricting A. However, in the power recovery process 10, depending on the mode, the control amount px is forcibly set below the control amount qx so as to jump over the gap region C shown in FIG. 4 (see the solid line arrow in FIG. 4). Therefore, the gas supply pressure p can be immediately controlled at the operating end A without a time delay.

In the above state, the gas supply pressure p is controlled at the operating end A, the output px of the pressure regulator 14 is 50% or less, and the turbine load q fluctuates within the allowable load range. . Under this condition, when the exhaust gas of the regenerator 11 increases rapidly due to a process change, the output px of the pressure regulator 14 increases and the operating end A is opened, but the turbine load q also increases. When the load q reaches the allowable set value, the output qx of the load controller 15 drives the operation terminal A in preference to the output px of the pressure controller 14, and the operation terminal A is maintained at a constant low opening. I will. At this time, the operating end B must be opened immediately to control the pressure. However,
In the this power recovery process 10, by that mode, the control amount px is as jump the gap region C shown in FIG. 2 forcibly operating end switching level p ₀ in (second see FIG dotted arrow) ( 50%) or more, the gas supply p can be immediately controlled at the operating end B without time delay.

Further, when the load of the generator 13 is interrupted in the above state, the operation of the safety protection mechanism causes the load controller 15 to operate.
Is forced to 0%, and the operation terminal A is fully closed.
In this case, the pressure regulator 14 must immediately open the operating end B to control the pressure. However, in the power recovery process 10, the control amount px
To the operating terminal switching level p ₀ (50%) or more, the gas supply pressure p is immediately changed to the operating terminal B without time delay.
Can be controlled.

That is, according to the power recovery process 10, the control by the operation end A and the control by the operation end B can be immediately switched to each other in response to the process change, and the gas supply pressure p can be quickly and accurately controlled. can do. Therefore, rapid pressure fluctuations in the gas supply source can be quickly controlled, and even when the exhaust gas from the regeneration tower 11 is small, the operation can be continued without opening the operation end B, and the maximum amount of power is always recovered,
A large increase in power generation can be expected.

FIG. 5 is a control circuit diagram showing a gas transfer process according to a second embodiment of the present invention.

In the gas transfer process 20, a gas from a gas supply source 21 is transferred by a centrifugal compressor 22 having a constant rotation. In the gas transfer process 20, the control variable p of the present invention is the suction pressure of the compressor 22, the control variable q is the output flow rate of the compressor 22, and the operating end A is the gas between the inlet and the outlet of the compressor 22. The recycle valve provided in the recycle flow passage, the operation end B is a bypass valve provided in the compressor bypass flow passage, (1) The operation end A is a suction pressure control amount output by the pressure regulator 23
Comparator for comparing px with flow control amount qx output by flow controller 24
25, the operation is performed with a control amount lower than the output of the comparison arithmetic unit 25, and (2) the operation terminal A operates under the condition that the suction pressure control amount px is in the range of 0% to 50%. , The operation end B has a suction pressure control amount px of 50%
Operating under conditions in the range of 100% (example operating end switching level p ₀ is set to 50%). 26 is a pressure detector and 27 is a flow rate detector. That is, when the suction pressure p rises in the above process, the operation end A is closed, and subsequently the operation end B is opened to control the suction pressure p to be constant. The operation end A is fully closed from the fully open state when the control amount px output from the pressure regulator 23 changes from 0% to 50%, and the operation end B is 50% when the control amount px output from the pressure regulator 23 is 50%. It changes from fully closed to fully open when converting to ~ 100%. The flow regulator 24 is for preventing surge of the compressor 22. In case of a decrease in flow due to closing of the valve at the gas transfer destination, the operation end A is opened to prevent surge by preventing the flow from dropping below the allowable set value. I do.

Thus, this gas transfer process 20 is
Takes the output qx of the load adjuster 24, and controls the control amount px and the control amount.
qx and the control variable px under the operating state of the operating end B
If it becomes less than p ₀ (50%), the control amount px is forcibly changed to the control amount qx or less so that the suction pressure p can be immediately controlled at the operation end A. When the control amount px relatively exceeds the control amount qx under the state, the control amount px is forcibly changed to the operating end switching level p ₀ (50%) or more, and the suction pressure p is immediately changed to the operating end switching level. B can be controlled.

Hereinafter, the operation of the gas transfer process 20 having the above configuration will be described.

In the normal operation state of the gas transfer process 20, the outlet flow rate of the compressor 22 is sufficiently larger than the surge flow rate,
The value fluctuates at a value larger than the allowable set value.
Output qx is at 100%. Also, the output px of the pressure regulator 23
Is not more than 50%. Therefore, by opening the operation end A, the pressure is controlled while a part of the gas is recycled.

In the above state, if the outlet flow rate of the compressor 22 decreases due to closing of the valve at the gas transfer destination, etc.
The output qx suddenly drops from 100%, and this output qx drives the operating end A in preference to the output px of the pressure regulator 23. The operating end A is opened to reduce the outlet flow q of the compressor 22. Maintain the flow rate at or above the surge generation point. At this time, since more gas than necessary is recycled to the compressor 22 and the suction pressure p rises, the operating end B must be immediately opened to control the pressure. However, in the gas transfer process 20, depending on the mode, the control amount px is forcibly set to the operating end switching level.
Since the pressure is changed to p ₀ (50%) or more, the suction pressure p can be immediately controlled at the operation end B without time delay.

Also, as described above, the outlet flow rate q of the compressor 22 is controlled at the operation end A to prevent surge, and the compressor 22 is controlled at the operation end B.
When the amount of gas supplied from the gas supply source 21 is reduced due to a process change while controlling the suction pressure p of the gas supply, the output px of the pressure regulator 23 is reduced to 50%, and If the pressure cannot be controlled even after closing, the operating end A
The pressure must be controlled at. However, in the gas transfer process 20, the control amount px is forcibly changed to be equal to or less than the output qx of the flow rate regulator 24 by the mode, so that the suction pressure p is immediately transmitted to the operation terminal A without time delay. Control.

That is, according to the gas transfer process 20, the control by the operation end A and the control by the operation end B can be immediately switched to each other in response to a process change, and the suction pressure p of the compressor 22 can be quickly and accurately controlled. can do.

As described above, the present invention has been described with respect to an industrial process for recovering or transferring gas from a gas supply source by a turbine or a compressor. However, the present invention is not limited to these, and is widely used in general industrial processes such as an energy generator using high-pressure water. Applicable to

[Effects of the Invention] As described above, according to the present invention, the control by the operation terminal A and the control by the operation terminal B can be immediately switched to each other in response to a process change, and the control variable p can be quickly and accurately adjusted. Can be controlled.

[Brief description of the drawings]

FIG. 1 is a control circuit diagram showing an industrial process according to the present invention,
FIG. 2 is a diagram showing the relationship between the operation amounts of the operation terminals A and B and the control amount px, FIG. 3 is a control circuit diagram showing a power recovery process according to the first embodiment of the present invention, and FIG. FIG. 5 is a diagram showing the relationship between the operation amounts of the operation ends A and B and the control amount px, FIG. 5 is a control circuit diagram showing a gas transfer process according to a second embodiment of the present invention, and FIG. FIG. 7 is a diagram showing the relationship between the operation amount and the control amount in the control method of the present invention. 1 ... industrial process, 2 ... first regulator, 3 ... second regulator, 4 ... comparator, 10 ... power recovery process, 11 ... regeneration tower (gas supply source), 12 ... Turbine, 13 Generator, 14 Pressure regulator, 15 Load regulator, 16 Comparator, 20 Gas transfer process, 21 Gas supply source, 22 Compressor, 23 …… Pressure controller, 24 …… Flow controller, 25 …… Comparator.

Claims (3)

(57) [Claims] 1. An operation terminal A for controlling two control variables p and q with two control variables p and q as control objects, and
An operation terminal B for controlling only the control variable p is provided, and the operation terminal A is driven by a lower control amount of the control amount px for the control variable p and the control amount qx for the control variable q, and control amount px is controls the control variable p at only operating end a when in the predetermined low-level side than the operation terminal switching level p ₀ for variable p, the control amount px for control variables p in advance In the industrial process control method in which the control variable p is controlled even at the control terminal B when the control terminal switching level p _{0 is} on the higher level side, the control variable px and the control variable q for the control variable p
The control amount px is always compared with the control amount qx, and if the control amount px becomes less than the operation end switching level p ₀ under the operating state of the operation end B, the control amount px is forcibly changed to the control amount qx or less. Then, the control variable p can be immediately controlled by the operation end A, and the control amount px is relatively controlled by the control amount qx under the operation state of only the operation end A.
If it exceeds, the control amount px forcibly changed to the operation end switch level p ₀ or more, the control of industrial processes, characterized in that to allow controlled by immediately operating end B of the control variables p Method. 2. The method according to claim 1, wherein the industrial process includes a gas supply turbine, the control variable p is a gas supply pressure, the control variable q is a turbine load, and the operating end A is provided in a turbine inlet flow path. The method for controlling an industrial process, wherein the inlet valve to be operated and the operation end B are bypass valves provided in the turbine bypass flow path. 3. The method according to claim 1, wherein the industrial process includes a gas supply source and a compressor, wherein a control variable p is a suction pressure of the compressor, a control variable q is an outlet flow rate of the compressor,
Is a recycle valve provided in a gas recycle channel between the inlet and the outlet of the compressor, and a control valve for an industrial process in which the operating end B is a bypass valve provided in a compressor bypass channel.