JPH07200066A - Method and device for controlling changeover of compressor - Google Patents

Abstract

PURPOSE:To automatize the changeover of nonlinear compressor supply ability by applying the weighting of plant parameters and the timing of changeover of judgement to the control of a membership function constructed based on the exprience of a skilled operator. CONSTITUTION:Either one of raw material feed out pumps 3 and 4 is operated and the changeover is performed by solenoid valves 5 and 6. A raw material is sent through a buffer tank 7 from a super-heating furnace 9 to a reaction tower 10 by a pump 10. By the signals of a flow meter 11, a controller 12 controls the flow rate of hydrogen for desulfurization by a control valve 13. The reaction tower 10 is divided into plural chambers and sulfer in the raw material gradually comes into reaction with the hydrogen while being pressurized and becomes hydrogen sulfide. At the time of leaving the reaction tower 10, the raw material, the hydrogen sulfide and the residual hydrogen are mixed and taken out. Only the raw material is taken out by a separation device 14 and becomes a product. The hydrogen and the hydrogen sulfide taken out of the separation device 14 are reproduced into the hydrogen for the desulfurization by a reproducing device 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to switching control of a multistage switching compressor in a plant. For more details,
The present invention relates to a compressor switching control method to which fuzzy logic control is applied.

[0002]

2. Description of the Related Art In a plant for oil refining, for example, a large amount of fluid flows through pipes, and very large valves and compressors are used for controlling the flow rate. However, in addition to such main flow rate control, various substances such as a catalyst may be added in the production process. In such a case, the control does not need to be so precise, but the fluid must be supplied by the compressor just enough to prevent the flow rate from becoming insufficient. Then, the control was performed by a person, while looking at the reaction of the plant, the flow rate of each pipe, etc., based on experience and intuition.

For example, in a desulfurization plant for kerosene or light oil,
Hydrogen is added to a raw material containing a sulfur content, and heated and pressurized in a reaction tower to generate hydrogen sulfide, and the sulfur content is removed. The hydrogen added at this time is pressurized by a compressor and sent to the reaction tower, but a compressor whose capacity is usually switched to about 3 to 5 stages is used. In reality, hydrogen is regenerated from the generated hydrogen sulfide and reused.Therefore, the operator should check the reaction in the reaction column, the amount of recycled hydrogen returned, the amount added, etc. to prevent hydrogen shortage. I was switching the compressor. In particular, at the time of switching the raw material, the addition amount changes depending on the quality and the amount of the raw material, so that the operator has to perform a very careful control.

[0004]

By the way, in the compressor in the plant as described above, a compressor having several stages of switching ability is used because of the large flow rate and the fact that the compressor cannot directly control the flow rate. Is normal. Although there are compressors that can be linearly controlled, although they are expensive, there is not much point in making them linear because they are compressors for supplying fluid as described above.

Therefore, the compressor used in such a place is still a multi-stage compressor at present. However, if this is done, the control of this compressor will still have to rely on human intuition. Absent. Even if a linear compressor is used, it still requires human control.

However, the actual switching timing of the compressor is a result of experience and intuition while looking at various parameters, and cannot be easily done by anyone. However, even if accurate control is applied, it is useless because the control is non-linear control of several stages. The present invention provides a control method and apparatus for automatically performing compressor switching, which has such a very rough control as to timing but has a very high degree of skill.

[0007]

In order to achieve the above-mentioned object, the present invention multiplies a plant function required for compressor switching control by a membership function representing each weight and obtains the sum thereof, and then the compressor. This is a method of determining the compressor capacity by multiplying the membership function that determines the switching of the.
A compressor to be controlled, a plant parameter detecting means necessary for compressor switching control, a switching control means for performing a calculation for switching the compressor based on signals from these detecting means, and a compressor from the signal from the switching control means. It consists of switching means for switching,
In the switching control means, the control parameters detected by the plant parameter detecting means are multiplied by a membership function representing each weight, the sum is calculated, and then a membership function for determining switching of the compressor is multiplied. And outputs a compressor switching signal.

[0008]

With the above construction, the weighting of plant parameters and the timing of switching judgment can be applied to the control by the membership function constructed based on the experience of a skilled operator, so that the non-linear compressor supply capacity switching can be automated.

[0009]

EXAMPLES Examples of the present invention will be described in detail in the examples of the desulfurization plant for kerosene and light oil described above. FIG. 1 is a block diagram of a desulfurization plant to which the present invention is applied.

Reference numeral 1 is a kerosene raw material tank, and 2 is a light oil raw material tank. Both raw materials contain sulfur and cannot be shipped as a product as they are. Since the content of this sulfur content also differs depending on the origin of crude oil, even if the same kerosene cannot be processed by the same desulfurization process, desulfurization is complicated. The purpose of this desulfurization device is to remove these sulfur components.

Reference numerals 3 and 4 denote pumps for feeding the raw material, one of which is operated, and switching is performed by electromagnetic valves 5 and 6. The raw material is sent from the heating furnace 9 to the reaction tower 10 by the pump 8 via the buffer tank 7. Pump 8
Immediately after that, a flow meter 11 is attached to monitor the amount of charge to the reaction tower. The controller 12 controls the flow rate of desulfurizing hydrogen by the control valve 13 based on the signal from the flow meter 11. At this time, considering the already known sulfur content of the raw material, hydrogen proportional to the charge amount is mixed into the raw material line.

The raw material mixed with hydrogen is heated in the heating furnace 9 and then placed in the reaction tower 10. The inside of the reaction tower is divided into a plurality of chambers, and while pressurizing, the sulfur in the raw material gradually reacts with hydrogen to become hydrogen sulfide. When leaving the reaction tower 10, the raw material, hydrogen sulfide, and excess hydrogen are mixed and taken out. Although not described in detail, only the raw material is taken out by the separating device 14 to obtain a product. The reaction tower 10 may be divided into a plurality of stages.

The hydrogen and hydrogen sulfide taken out by the separator 14 are regenerated into desulfurizing hydrogen by a regenerator 15, although this will not be described in detail either. This hydrogen is returned to the original hydrogen line via compressor 16B. The original hydrogen is supplied from a hydrogen supply (not shown) and sent to the hydrogen supply line via the compressor 16A.
Since the desulfurizing hydrogen is controlled by the control valve 13 as described above, the compressor capacity is set so that the compressors 16A and 16B have a capacity higher than the flow rate supplied to the lines. The capacity setting of the compressor is actually nothing but the setting of the motor 17.

By the way, the compressors 16A, 16B
Since the (motor 17) has only an extremely rough set value of about 3 to 5 steps, if the setting is made so that the supply amount is not insufficient, excessive hydrogen will be fed, and if this is left as it is, the static pressure applied to the control valve 13 will be increased. Therefore, accurate flow rate control cannot be performed. Therefore, the compressor 16
A feedback loop is provided immediately after the output of A to return excess hydrogen to the front stage of the compressor 16A, which is called spillback.

Although the desulfurization apparatus itself is configured as described above, some configurations are added to this in the present invention. Before explaining the above, first, considering the parameters related to the supply (consumption) of hydrogen, the following various quantities are listed. (1) Spillback amount (2) Reaction tower temperature (reaction temperature) (3) Reaction tower pressure (reaction pressure) (4) Charge amount (5) Sulfur content rate Hydrogen consumption by comprehensively judging these parameters Changes, and the supply amount also changes accordingly.

Therefore, the flow rate by the control valve 13 can only supply hydrogen proportional to the charge amount in (4) and set a proportional constant in consideration of the sulfur content in (5).
No consideration was given to the increase or decrease in consumption depending on the reaction condition. That is, in the past, the operator manually set the flow rate here.

In the present invention, a sensor for detecting these parameters is provided, that is, the flowmeter 1 for measuring the spillback amount.
8. A thermometer 19 for measuring the temperature in the reaction tower and a pressure gauge 20 for measuring the pressure are newly provided, and at the same time, a signal from the flow meter 8 as a charge amount sensor is input to the controller 21 having a built-in computer. The controller outputs the motor 17 based on the control output calculated based on the input parameters.
The changeover control means 22 for changing over is changed over.

Next, the calculation by the computer in the controller 21 will be described. Controller 21
Interface of control signal, input signal,
It has a man-machine interface, an interface with a host controller, etc., and is connected to a built-in computer. Computer is CPU, RO
It has a basic configuration such as M and RAM.

In the control according to the present invention, fuzzy theory is applied, and the compressor switching judgment obtained from the operating know-how of a skilled operator is constructed as a membership function, and the switching operation is automatically performed based on this. is there. As a method, a sensor signal to be monitored is multiplied by a membership function of weighting, and a summation thereof is further multiplied by a membership function of switching judgment to construct a judgment algorithm, and while considering the mutual relationship of input signals, At this point, the operator will predict that the compressor will be switched.

FIG. 2 is a flowchart showing the above judgment. In step 23, the sensors 19, 2
From 0, 11, and 18, temperature, pressure, charge amount,
Take in the spillback amount (see arrow in the figure). At this time, a plurality of pressures and temperatures may be provided depending on the structure inside the reaction tower 10. Although the charge amount is taken from the inside of the controller 12, the function of the controller 12 itself can be taken into the controller 21 and controlled. Further, the sulfur content is also closely related to the hydrogenation here, but since it is known in advance depending on the type of oil, it can be omitted here.

At 24, the membership values Mt, Mp, Mq, and Ms are read from the memory and multiplied by the signal value obtained at 23, respectively. As the membership function at this time, for example, a function is used that determines which parameter range and at which stage the compressor motor is switched when other parameters are fixed for each parameter.

At 25, the total sum SM of the values obtained at 24 is obtained, and at 27, the membership function Md for switching judgment is added to this.
Multiply The switching signal is based on this value, is compared with the threshold value for each switching stage (28), and the switching signal is output (29).

[0023]

According to the method and apparatus for switching a compressor of the present invention, an operation that requires experience and intuition to make a judgment, regardless of the simple operation of switching several stages that are not continuous,
Since it can be automated, it has a great effect on labor saving. Also, especially in large and medium-sized plants, due to the size of the manipulated variable, etc., there are still relatively relatively rough controls as described above, rather than precise controls, which is a very effective control method for such plants. .

[0024]

[Brief description of drawings]

FIG. 1 is a configuration diagram of a plant showing an embodiment to which the present invention is applied.

FIG. 2 is a flowchart showing calculation and judgment in the computer of the present invention.

[Explanation of symbols]

 1, 2 Raw material tanks 3, 4, 8 Pump 9 Heating furnace 10 Reaction tower 14 Separation device 15 Regeneration device 16A, 16B Compressor 11, 18, 19, 20 Sensor 12, 21 Controller 17 Motor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yusuke Fukuda 2-12-19 Shibuya, Shibuya-ku, Tokyo Token International Building Yamatake Honeywell

Claims (2)

[Claims] Claim: What is claimed is: 1. A plant parameter required for switching control of a compressor is multiplied by a membership function that represents a weight, the sum of them is calculated, and then a membership function that determines switching of the compressor is multiplied to determine the compressor capacity. How to determine the compressor switching method. 2. A compressor to be controlled, a plant parameter detecting means necessary for switching control of the compressor, a switching control means for performing a calculation for switching the compressor based on signals from these detecting means, and the switching control means. Consisting of switching means for switching the compressor by the signal of, in the switching control means, the control parameter detected by the plant parameter detection means is multiplied by a membership function representing each weight, and after obtaining the sum thereof, A compressor switching control device, which further outputs a compressor switching signal by multiplying a membership function that determines switching of the compressor.