JP3282885B2 - How to switch raw materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for switching raw materials, and can be used for switching a plurality of crude oil tanks which are a supply source of crude oil used as a raw material for an oil plant.

[0002]

2. Description of the Related Art Conventionally, in a petroleum plant, a plurality of discharge pumps are provided in parallel on a downstream side of a plurality of crude oil tanks as a supply source of crude oil as a feedstock, and a charge pump is provided on a downstream side of these discharge pumps. Crude oil supply equipment is used. In such a supply device, crude oil extracted from a crude oil tank by a delivery pump is pressure-fed by a charge pump to supply the crude oil to a desalter or the like. Further, a switching valve is provided between each delivery pump and each crude oil tank, and by switching each pipe by operating each switching valve, different types of crude oil accumulated in each oil tank can be switched. It has become. The plurality of dispensing pumps are such that each of the activated pumps delivers a predetermined flow rate of crude oil.
The flow rate is individually controlled, and at least one of the pumps is always stopped as a backup pump. When switching crude oil,
After additionally activating the stopped spare pumps, the activated dispensing pumps are sequentially stopped one by one, and the switching valves of the stopped dispensing pumps are operated to switch the crude oil.

[0003]

However, in the conventional switching method, switching is performed in a state where the flow rates of a plurality of delivery pumps are individually controlled. Therefore, when the backup pumps are started, each control system is activated by the startup of the backup pumps. There is a problem that these control operations interfere with each other to cause a hunting operation, and the control operation becomes unstable.In some cases, the charge pump stops due to a change in suction pressure, The dispense pump may have to be stopped to stop the hunting operation. On the other hand, it is conceivable to prevent the hunting operation by delaying the operation of each control system, but if the control operation is delayed,
There is a problem that the operation time of the backup pump that does not need to be operated normally becomes longer, the time during which wasteful power is consumed is prolonged, and energy is wasted.

[0004] It is an object of the present invention to provide a method of switching raw materials that can stabilize the control operation and reduce the waste of energy.

[0005]

According to the present invention, there are provided a plurality of raw material supply sources, a plurality of discharge pumps connected in parallel to the raw material supply sources, and a plurality of discharge pumps connected between the discharge pumps and the respective raw material supply sources. In switching the raw material of the raw material supply device including a connected switching valve and a charge pump provided on the discharge side of the discharge pump and feeding the raw material to another device connected downstream, control at the time of raw material switching Of raw material for controlling the suction pressure of the charge pump and the total flow rate from each dispensing pump to a predetermined value.
This is a replacement method.
Some of the pumps were stopped alternately and stopped.
By operating the dispensing pump switching valve,
When switching from one source to another source
Next, stop the target pump to be switched
The flow rate of the additional start-up pump activated for
Until the flow rate of the elephant pump reaches the
Pumps other than the additional start-up pump
And the flow rate is adjusted to the predetermined flow rate value.
Note that the flow rate must be equal to the difference
Performing a first control mode to control the pump,
After the flow rate reaches the flow rate of the switching target pump,
Pumps other than the pump to be switched including the additional startup pump
The pump flow rate is controlled collectively and this flow rate is
The difference between the predetermined flow rate value and the flow rate of the pump to be switched, etc.
A second control mode for controlling the flow rate so as to make it easier.

[0006] Here, in the above-mentioned method of switching raw materials,
To change the raw material of the raw material supply device
The multiple dispensing pumps are alternately arranged one by one
Can be stopped. Further, it is preferable that the first control mode is started after the suction pressure of the charge pump has increased by a predetermined value due to the activation of the additional activation pump.

[0007]

According to the present invention, since the total flow rate of each discharge pump is controlled to a predetermined value, the control operations do not interfere with each other, and the suction pressure of the charge pump is kept constant. The operation becomes stable, and the control operation becomes stable. And
A first control mode for collectively controlling the flow rates of a plurality of pumps other than the additional startup pump is performed when the additional startup pump is started, and the flow rates of a plurality of pumps other than the switching target pump are collectively controlled when the switching target pump is stopped. By performing the second control mode, the control is performed such that the sum of the two flow values to be controlled becomes a predetermined flow value in each mode. It will be commanded and will not interfere with each other. In addition, when the flow rate of the additionally activated pump reaches the flow rate of the pump to be switched, the mode shifts from the first control mode to the second control mode. Therefore , it is necessary to change control parameters such as target values and set values at the time of mode shift. Mode can be quickly and smoothly switched, and in the second control mode, control can be performed regardless of the operating state of the pump to be switched.
Stoppage of the pump to be switched does not cause disturbance. For this reason, stable control can be performed all the time, and the switching of the raw materials can be performed in the shortest time, thereby achieving the above object.

[0008]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a crude oil supply device 1 which is a material supply device of the present embodiment. This crude oil supply device 1 has two systems of crude oil tanks 1A and 1B, which are raw material supply sources, and supplies crude oil to a desalter and the like connected downstream via a transport line L. Each of the crude oil tanks 1A and 1B is connected in parallel with four lines of series A to D.
Discharge pumps 2A, 2B, 2C, 2D for extracting crude oil from the crude oil tanks 1A, 1B are connected to the series A to D, respectively. One of the delivery pumps 2A, 2B, 2C, and 2D is sequentially used as a backup pump so that the operation is rested in order, so that the operation time is equalized.

Discharge pump 2A and each crude oil tank 1A, 1B
Switching valves 3AA and 3BA are connected between the discharge pump 2B and the crude oil tanks 1A and 1B.
B, 3BB, switching valves 3AC, 3BC are connected between the discharge pump 2C and each crude oil tank 1A, 1B, and switching valves 3AD, 3BD are connected between the discharge pump 2D and each crude oil tank 1A, 1B. I have. Switching valve 3AA, 3AB, 3AC, 3AD
Pairs with the switching valves 3BA, 3BB, 3BC, 3BD, respectively.
When one is open, the other is set to close,
As a result, the switching between the crude oil tanks 1A and 1B is performed.

The discharge side of each of the discharge pumps 2A, 2B, 2C, 2D is
Charge pump 4 that sends crude oil to desalter etc.
It is connected to the. Flow sensors 5A, 5B, 5C, 5D and flow regulating valves 6A, 6B, 6C, 6D are connected between the discharge pumps 2A, 2B, 2C, 2D and the charge pump 4, respectively. The flow rate sensors 5A, 5B, 5C, 5D are composed of orifices, differential pressure transmitters and the like, and measure the instantaneous flow rate of crude oil flowing from the discharge pumps 2A, 2B, 2C, 2D. The flow control valves 6A, 6B, 6C, 6D adjust the flow rate of crude oil flowing from the discharge pumps 2A, 2B, 2C, 2D based on signal values measured by the flow sensors 5A, 5B, 5C, 5D. Things.

A pressure transmitter 7 is provided on the suction side of the charge pump 4 so that the suction pressure of the charge pump 4 is measured. On the other hand, two branch paths 8 are provided on the discharge side of the charge pump 4, and a desalinator is connected to each branch path 8, and in order to control the flow rate of crude oil flowing inside to a predetermined value, The flow sensor 8A and the flow control valve 8B are connected. In addition, the flow control valve
8B is a flow indication controller to which the signal of the flow sensor 8A is input.
It is controlled by 8C.

Such a crude oil supply device 1 is controlled by an instrumentation line indicated by a broken line in the figure. Next, an instrumentation system of the crude oil supply device 1 will be described. Flow sensor 5A, 5
The outputs of B, 5C, and 5D are the same series of flow indicator controllers 9A, 9B, 9
C and 9D respectively. All outputs of these flow sensors 5A, 5B, 5C, 5D are also connected to a programmable flow rate controller 10 which can be programmed arbitrarily.

The flow rate indicating controllers 9A, 9B, 9C, 9D are controllers for individual control for controlling the degree of opening of the flow control valves 6A, 6B, 6C, 6D based on one input flow signal. . The flow rate indicating controller 10 has two control systems, a control system consisting of one designated system out of the systems A to D, and a control system integrating the other three systems into one. By controlling the entire system, the overall flow rate can be reduced to a predetermined value C _Q
It is configured to keep. For example, three series A ~
When the series D is designated out of C and the amount of crude oil flowing in the series D is increased or decreased, the flow rate indicating controller 10 adds the amounts of the crude oil flowing in the series A to C to each other and calculates a flow rate value which is a sum of the amounts. together determine the Q _G, determined for these differences Delta] Q from the target value C _Q by subtracting the flow rate value Q _D flowing through the series D, the flow rate value Q _G is the flow rate control valve 6A so that ΔQ, 6B, 6C
Is controlled so that the overall flow rate value Q _T is constant. Here, the flow control valves 6A, 6B, 6C are:
They are controlled collectively and perform the same operation.

The flow rate indicating controller 10 has two control modes, a first control mode and a second control mode, and monitors the output of the flow rate sensors 5A, 5B, 5C and 5D while controlling the flow rate conditions. The operation is performed by switching the control mode according to the operation. That is, the first control mode includes the dispensing pumps 2A and 2A.
When one of the pumps B, 2C, and 2D, which was stopped as a backup pump, was additionally started, the flow rates of the other three pumps were adjusted collectively according to the increase in the flow rate of the additionally started pump.
This is a control mode to make the whole flow rate constant,
The flow is continued until the flow rate of the additionally started backup pump reaches the flow rate of the switching target pump which is stopped for switching.

[0015] The second control mode is a dispensing pump.
When stopping the pump to be switched among 2A, 2B, 2C, and 2D,
This is a control mode in which the flow rates of the other three pumps are adjusted collectively according to the decrease in the flow rate of the pump to be stopped, so that the overall flow rate is constant. After reaching the flow rate of the switching target pump that is stopped for the above, the processing is continued until the switching target pump is stopped.

A signal switch 11 is connected between the flow control valve 6A and the flow indication controller 10. Signal switch 11
Is also connected to the flow indication controller 9A,
This is a device for switching a signal input to 6A from one of the flow rate controller 9A and the flow rate controller 10 to the other. A signal switch 11 is also connected between each of the other flow control valves 6B, 6C, 6D and the flow indicator controller 10.

The output of the pressure transmitter 7 is supplied to a pressure indicating controller 12.
The deviation ΔP between the input pressure value and the set pressure value is output from the pressure indicating controller 12 to the sequence controller 20. The sequence controller 20 includes the dispensing pumps 2A, 2B, 2C, 2D and the switching valve
3AA, 3BA… 3AD, 3BD etc. operation and flow rate controller
This is to control the 10 control operations as a whole. That is, the sequence controller 20 includes the pressure indicating controller 12
, The operating state signals of the discharge pumps 2A, 2B, 2C, 2D, and the switching valves 3AA, 3BA ... 3AD, 3BD
Open / close state signal is input. The sequence controller 20 outputs start / stop signals to the discharge pumps 2A, 2B, 2C, and 2D, and switches valves 3AA, 3BA ... 3AD, 3B
An open / close signal is output to D. Pump 2
During operation of A, 2B, 2C, 2D, switching valve 3AA, 3BA… 3A
An interlock is provided to prevent D and 3BD from operating. A control signal for switching the flow control from the individual control for each of the series A to D to the group control for controlling a plurality of series A to D collectively is output to the flow rate indicating controller 10 and the signal switch 11. It has become. here,
The control signals to the flow rate indicating controller 10 and the signal switch 11 are
Output after the deviation ΔP between the suction pressure value of the charge pump 4 and the set pressure value becomes larger than a predetermined value. Upon receiving this control signal, the flow rate indicating controller 10 starts control in the first control mode. It is supposed to. Then, after the first control mode is started, the output of the deviation ΔP of suction pressure values of the charge pump 4 and the set pressure value, the flow indicating controller meter 10 to a constant total flow rate value Q _T Is controlled.

Next, a procedure for switching crude oil according to the present embodiment will be described with reference to FIG. In addition, the switching of crude oil is performed by the delivery pump
The operations are performed in the order of 2A, 2B, 2C, and 2D, the crude oil is supplied from the crude oil tank 1A, and the operation is started in a state in which the discharge pump 2D among the discharge pumps 2A, 2B, 2C, and 2D is stopped as a backup pump.

First, in switching the crude oil of the delivery pump 2A, as shown in FIG. 2, a spare pump 2D is started at time T1. When the pump 2D is started, the suction pressure of the charge pump 4 increases and the deviation ΔP from the set value immediately reaches a predetermined value, and the flow rate indicating controller 10 starts the first control mode. In the first control mode,
As shown on the time i in FIG. 2, the pump with the 2D flow increases, pump 2A, 2B, squeezed collectively flow rate value Q _A Q _B Q _C of 2C, the overall flow rate value Q _T is the target value Control is made to be C _Q. As a result, the flow rates of the pumps 2A, 2B, and 2C are controlled collectively, and mutual interference of control operations is prevented, thereby preventing the occurrence of a hunting phenomenon or the like.

[0020] At time T2, pump 2D flow value Q _D and the flow rate value Q _A is next both values Q1 pump 2A, the control mode of the flow indicating controller meter 10, the second control mode from the first control mode Move to. In the second control mode, as shown on the time b in FIG. 2, with the flow reduction of the pump 2A, increasing pump 2B, 2C, the flow rate value Q _B Q _C Q _D of 2D collectively, the overall flow rate Control is performed so that the value Q _T becomes the target value C _Q. As a result, the flow rates of the pumps 2B, 2C, and 2D are collectively controlled, mutual interference of control operations is prevented, occurrence of a hunting phenomenon or the like is prevented, and even if the pump 2A is stopped, the pumps 2B, 2C , the flow rate value Q _G and overall flow rate value Q _T total of 2D is as a second deviation without the control operation from the controllable range in the control mode is stabilized.

For each of the other delivery pumps 2B, 2C, and 2D, the switching of crude oil is performed in the same manner, and the entire switching of crude oil is completed. However, when the pump 2B is switched, the spare pump is the pump 2A, when the pump 2C is switched, the spare pump is the pump 2B, and when the pump 2D is switched, the spare pump is the pump 2C.

According to the above-described embodiment, the following effects can be obtained. That is, the first control mode for collectively controlling the flow rates of a plurality of pumps other than the standby pump is performed at the time of starting the standby pump, and the flow rates of the multiple pumps other than the target pump are collectively controlled at the time of stopping the target pump. The second control mode for controlling is performed, and in each mode, the control is performed such that the sum of the flow values of the two control systems becomes a predetermined flow value. Therefore, the control operation can be stabilized from time to time without interfering with each other.

When the flow rate of the backup pump reaches the flow rate of the pump to be switched, the mode is shifted from the first control mode to the second control mode. It is not necessary to change the control parameters such as, and the mode can be switched quickly and smoothly, and even if the pump to be switched is stopped, the entire flow rate value is out of the controllable range in the second control mode. Since the pump does not deviate, the stoppage of the switching target pump does not cause a disturbance, and the raw material can be switched in the shortest time.

Further, in performing the above-described crude oil switching procedure, it is not necessary to add any new on-site equipment to the crude oil supply device 1, and it is sufficient to add a new controller such as the flow rate indicator controller 10 or the like. It is possible to easily convert from the switching procedure to the actual switching procedure.

The present invention is not limited to the above-described embodiment, but includes the following modifications. That is, in the above embodiment, the number of the dispensing pumps was set to four, and one of them was used as a spare. However, eight small dispensing pumps were used, and two of them could be used as spare pumps. Can be appropriately set in consideration of the operation rate and the like.

The flow rate sensor can be selected from various types such as an axial flow type with a built-in turbine and the like, and an oval type positive displacement type, and the type of other instruments can be appropriately selected. Further, the present invention is not limited to a crude oil supply apparatus, and can be widely applied to a raw material supply apparatus in a food processing industry for dairy products and the like and a paint manufacturing industry.

[0027]

As described above, according to the present invention, the control operation can be stabilized and the waste of energy can be reduced.

[Brief description of the drawings]

FIG. 1 is an instrumentation flow chart showing an entire embodiment of the present invention.

FIG. 2 is a graph for explaining a procedure for switching crude oil according to the present invention.

[Explanation of symbols]

1A, 1B Crude oil tank which is a raw material supply source that supplies liquid raw material 2A, 2B, 2C, 2D Discharge pump 3AA, 3BA ‥‥‥ 3AD, 3BD Switching valve 4 Charge pump

Continuation of front page (58) Fields investigated (Int. Cl. ⁷ , DB name) F17D 1/14 B01J 4/00 C10G 21/30 C10G 49/26

Claims (3)

(57) [Claims] A plurality of feed sources, a plurality of delivery pumps connected in parallel to the feed sources, a switching valve connected between each delivery pump and each feed source, In switching the raw material of the raw material supply device having a charge pump that is provided on the discharge side of the discharge pump and sends the raw material to another device connected to the downstream side ,
A raw material switching method for controlling the raw material switching so that the suction pressure of the charge pump and the total flow rate from each of the discharging pumps become a predetermined value, and among a plurality of operating discharging pumps, That one
Parts are stopped alternately one after another, and the stopped discharge pump is switched.
By operating the valve, you can switch from one source to another.
When switching to the raw material of the raw material supply source, to stop the target pump to be switched
The flow rate of the additional startup pump started at
Before the pump flow rate is reached, the pump to be switched
The flow rates of pumps other than the additional start-up pump including
This flow rate and the predetermined flow rate value and the
Flow control so that it is equal to the difference with the flow rate of the pump
A first control mode is performed, and the flow rate of the additional startup pump is changed to the flow rate of the pump to be switched.
After reaching the volume, the switching including the additional start-up pump
If the flow rates of pumps other than the target pump are controlled collectively
In both cases, the flow rate is the predetermined flow rate value and the switching target pump.
The flow rate is controlled to be equal to the difference between
A method for switching raw materials, comprising performing a control mode . 2. The raw material switching method according to claim 1, wherein a plurality of operating discharge pumps are operated one by one.
A method for switching raw materials, comprising sequentially and alternately stopping . 3. The switching method of the material according to claim 1 or claim 2, wherein the first control mode is started after the suction pressure of the charge pump rises by a predetermined value by the activation of the additional boot pump A method for switching raw materials, comprising: