JP3807788B2 - Gas balance control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas balance control device in an energy supply system, and more particularly to a gas balance control device for blending a plurality of gases having different purity in a balanced manner and supplying the gas to a gas consuming device.
[0002]
[Prior art]
In a refinery, hydrogen is generated in a catalytic reformer (PL) and a hydrogen production device (HY), and is mainly consumed in a heavy oil desulfurization device (RH) and a kerosene oil desulfurization device (2DH). In this case, in the catalytic reformer, hydrogen is generated as a by-product when low-octane straight-run gasoline is made into a high-octane gasoline material. Therefore, cheap hydrogen generated from this catalytic reformer is mainly used, and the required total hydrogen A shortage with respect to the amount is generated in the hydrogen production apparatus.
[0003]
Here, hydrogen generated in the catalytic reformer (hereinafter also referred to as PL hydrogen) has a lower purity than hydrogen generated in the hydrogen production apparatus (hereinafter also referred to as HY hydrogen) (60 to 80). %) PL hydrogen alone cannot operate hydrogen consuming equipment such as heavy oil desulfurization equipment and kerosene oil desulfurization equipment. On the other hand, although HY hydrogen has a high purity (99% or more), HY hydrogen is generated through a catalyst by adding a large amount of heat to butane or naphtha, and thus is more expensive than PL hydrogen.
Therefore, it is desired to make maximum use of PL hydrogen within a range in which hydrogen purity capable of operating the hydrogen consuming apparatus can be maintained.
[0004]
However, the purity and generation amount of PL hydrogen differs depending on the operation mode of the catalytic reformer and the raw material of the catalytic reformer, and it is necessary depending on the sulfur content of the raw material processed in the heavy oil desulfurizer and kerosene oil desulfurizer. The amount of hydrogen to be changed changes.
[0005]
On the other hand, in the operation of the heavy oil desulfurization apparatus and the kerosene oil desulfurization apparatus, it is necessary to maintain the hydrogen purity in the apparatus above a certain level regardless of the above-described situation of the catalytic reforming apparatus.
Furthermore, the change in the purity of hydrogen in each apparatus such as a heavy oil desulfurization apparatus and a kerosene oil desulfurization apparatus has a very large time delay and a non-linear response to changes in the amount of PL hydrogen fed.
For this reason, the conventional existing control method cannot automate the amount of PL hydrogen fed and manually adjusts it. During this manual adjustment period, a large amount of HY hydrogen was fed in consideration of safety.
As a result, PL hydrogen became surplus, and surplus PL hydrogen was used as an alternative to inexpensive fuel gas and was not effectively used.
[0006]
Under such circumstances, the pressure control of the hydrogen consuming apparatus has been conventionally performed in order to automate some control.
That is, for example, in kerosene oil desulfurization equipment, it is necessary to maintain an economical hydrogen purity of 80%. However, if only PL hydrogen is fed into the kerosene oil desulfurization equipment, the standard internal pressure of the equipment is 50 kg / It can not be maintained cm ^2. For this reason, while mainly supplying PL hydrogen, HY hydrogen is also supplied so that the internal pressure of the apparatus does not drop below 50 kg / cm ^{2. In} this case, the hydrogen purity is 80% or more, which is not economical.
[0007]
As described above, conventionally, the internal pressure of the kerosene oil desulfurization apparatus is observed. When the internal pressure is lower than 50 kg / cm ² , the supply amount of HY hydrogen from the hydrogen production apparatus is increased, and when the internal pressure is higher than 50 kg / cm ² , The balance of hydrogen was indirectly controlled by reducing the supply amount.
This pressure control is performed by a conventionally used DCS (distributed instrumentation computer) control system.
[0008]
[Problems to be solved by the invention]
However, in this pressure control method, since pressure control is the main purpose, accurate control of the hydrogen purity cannot be performed. Therefore, in consideration of safety, HY hydrogen is supplied in excess, and PL hydrogen still remains. Was surplus.
[0009]
Note that multivariable predictive control is an effective control method for a system with a large time delay (a system that takes time for the operation to take effect). However, this method is effective for a system showing a linear response, but is not suitable for a nonlinear system such as hydrogen balance control.
[0010]
In addition, a method using mathematical programming, in which the entire system is converted into a mathematical model and the optimum PL hydrogen feed amount is calculated by mathematical programming, can be considered. However, this method is not practical for a system with a time delay because it requires an optimization calculation while predicting the future each time the system state changes.
[0011]
Furthermore, it is conceivable to use a control method for correcting the statistical model by fuzzy reasoning. As this control method, for example, Yanagishita, Ito, Kanno “Application of fuzzy theory to water plant chemical injection control”, system and control, vol. 28, no. 10, pp. 597-604 (1984).
However, in this case, the model is fixed, and all differences between the model and the actual state are corrected by fuzzy reasoning, so various cases must be assumed for fuzzy reasoning, which is very complicated and impractical. .
[0012]
The present invention has been made in view of the above circumstances, and has a large time delay and automates the balance (purity) control of hydrogen that forms a nonlinear control system. An object of the present invention is to provide a control device that optimizes the mixing ratio of hydrogen according to the conditions of the hydrogen consuming device.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, a gas balance control device according to claim 1 of the present invention is an energy supply system in which a plurality of gases are mixed and supplied to a gas consuming device, wherein the gas purity in the gas consuming device is a predetermined purity. A gas balance control device including a purity control unit that controls the gas pressure in the gas consuming device to be a predetermined pressure, and the purity control unit is in a steady state. The gas consumption prediction amount is obtained, the difference between the predicted gas consumption amount and the actual gas consumption amount is compensated, and the change in the purity of the supply gas is controlled by fuzzy control .
[0014]
In addition, the gas balance control device according to claim 2 performs the fuzzy control according to a fuzzy control rule created based on characteristics of a transient gas consumption prediction model created based on data of a transient state obtained in advance. The configuration is to be performed.
[0015]
In addition, the gas balance control device according to claim 3 uses a high purity gas and a low purity gas having different purity as the plurality of gases, and the purity control unit has a gas purity in the gas consuming device of a predetermined purity. The low-purity gas is supplied while being controlled so that the pressure control unit supplies the high-purity gas while controlling the pressure in the hydrogen consuming apparatus to be a predetermined pressure.
[0016]
According to a fourth aspect of the present invention, when there are a plurality of gas consuming devices , the gas balance control device determines the priority of the gas consuming devices that supply the gas, and performs the gas distribution control based on the priority. It is set as the structure provided with a part.
[0017]
In the gas balance control device according to claim 5, the gas is hydrogen gas, the high purity gas is hydrogen gas generated from a hydrogen production device, and the low purity gas is generated from a catalytic reforming device. The configuration is as follows.
[0018]
[Embodiments of the Invention]
Hereinafter, an embodiment of the gas balance control device of the present invention will be described.
First, a hydrogen balance control system to which the control device of the present invention is applied will be described.
FIG. 1 is a block diagram showing the entire hydrogen balance control system.
[0019]
In the figure, reference numeral 1 denotes a catalytic reformer (PL), which generates low-cost low-purity hydrogen as a by-product when producing a high-octane gasoline material. A hydrogen production apparatus 2 generates a high-priced, high-cost hydrogen through a catalyst by adding a large amount of heat to butane or naphtha.
3 and 4 are a heavy oil desulfurization device (RH) and a kerosene oil desulfurization device (2DH) as hydrogen consumption devices.
[0020]
Here, the generation amount and purity of PL hydrogen vary depending on the operation mode of the catalytic reformer and the raw material of the catalytic reformer. On the other hand, the amount of hydrogen consumed in heavy oil desulfurization equipment and kerosene oil desulfurization equipment varies depending on the sulfur content in the raw material to be treated.
Note that no matter how high the purity of PL hydrogen, the purity in the hydrogen consuming apparatus cannot be maintained at 80% with only PL hydrogen. Therefore, high purity HY hydrogen is added so that the purity in the hydrogen consuming apparatus is 80%.
[0021]
The control device of the present embodiment performs the balance control of hydrogen in the process as described above, and is provided between the hydrogen consumption device including the catalytic reforming device 1 and the heavy oil desulfurization device 3 and the kerosene oil desulfurization device 4. The purity control unit 10 arranged controls the supply amount of PL hydrogen to control the hydrogen purity in the heavy oil desulfurization device 3 and the kerosene oil desulfurization device 4, and the hydrogen production device 2 and the heavy oil desulfurization device 3 The pressure control unit 20 disposed between the kerosene oil desulfurization device 4 controls the supply amount of HY hydrogen to control the pressure in the heavy oil desulfurization device 3 and the kerosene oil desulfurization device 4.
[0022]
Here, the purity control and the pressure control are performed independently, respectively, the purity control is performed by a purity control unit described later, and the pressure control is performed by a pressure control unit using DCS described above.
Although the purity control and the pressure control are performed independently, they interfere with each other because the controlled object is the same, but in the present invention, the pressure control with a quick response is made to follow the purity control, so that there is a problem in practice. Don't be.
[0023]
That is, as will be described later, the purity control unit slowly adjusts the supply amount of PL hydrogen to the hydrogen consuming device in order to control the hydrogen purity. For example, the hydrogen purity is low due to various factors at this time. In this case, the purity control unit reduces the supply amount of PL hydrogen to increase the hydrogen purity to an appropriate level, and the pressure temporarily decreases.
Therefore, the hydrogen pressure is always set to the reference pressure by increasing the pressure by pressure control with a fast response speed.
[0024]
Next, the purity control unit will be described.
FIG. 2 is a block diagram showing an embodiment of the purity control unit.
The purity control unit 10 is for sending the maximum amount of PL hydrogen from the catalytic reformer 1 while observing the state of the heavy oil desulfurization device 3 and the kerosene oil desulfurization device 4. It consists of a fuzzy control unit 12.
Here, the hydrogen consumption prediction model unit 11 predicts a standard hydrogen consumption based on the hydrogen consumption prediction model, and compensates for the difference between the predicted steady-state hydrogen consumption prediction and the actual hydrogen consumption. It has become.
Further, the fuzzy controller 12 appropriately controls the standard hydrogen consumption by catching changes in the PL hydrogen purity and the hydrogen purity of the hydrogen consuming apparatus.
[0025]
Specifically, the hydrogen consumption prediction model unit 11 includes a steady state hydrogen consumption prediction model unit 11a and a correction unit 11b. The steady state hydrogen consumption prediction model unit 11a is a standard using statistical methods and fuzzy inference. To calculate the correct hydrogen consumption. Further, the correction unit 11b constantly monitors an error between the predicted consumption calculated by the hydrogen consumption prediction model unit 11a and the amount actually consumed by the heavy oil desulfurization device 3 and the kerosene oil desulfurization device 4 to predict the amount. Is adjusted to approach actual consumption. As a result, hydrogen consumption can be accurately predicted at a time close to the present time.
[0026]
The fuzzy control unit 12 grasps a change in the situation such as when the purity of supplied hydrogen changes, and changes the amount of hydrogen sent to the apparatus in a feed-forward manner in order to immediately respond to the change.
[0027]
The control method of PL hydrogen performed by the purity control unit is as follows.
First, in the steady state hydrogen consumption prediction model unit 11a, the prediction model is created by statistically processing the steady state operation data shown in FIG.
Specifically, the operation data is decomposed into a plurality of sections, and the decomposed sections are expressed by a linear model. And the whole (especially between linear models) is complemented by fuzzy reasoning.
For example, when the hydrogen consuming device is a kerosene oil desulfurization device 4, the hydrogen concentration at the outlet is measured, the amount of hydrogen supplied is determined based on a linear model, and complemented by the following fuzzy inference.
The throughput of IF 2DH is high
Hydrogen consumption = a ₁ x treatment amount + a ₂ x desulfurization rate + ...
IF 2DH throughput is medium THEN
Hydrogen consumption = b ₁ × throughput + b ₂ × desulfurization rate + ...
The throughput of IF 2DH is low
Hydrogen consumption = c ₁ × treatment amount + c ₂ × desulfurization rate +.
Here, a ₁ , a ₂ ..., B ₁ , b ₂ ..., C ₁ , c ₂ .
Hereinafter, such a model for predicting hydrogen consumption is referred to as a fuzzy model.
[0028]
The predicted hydrogen consumption in this way makes a difference with the measured actual hydrogen consumption. For this reason, in the correction | amendment part 11b, it correct | amends so that prediction may approximate actual consumption.
That is, the correction unit 11b repeats the following steps (exponential averaging method).
The n-th predicted hydrogen consumption amount y _i (bar) is obtained by y _i (bar) = fuzzy model + e _i (bar).
When the measured hydrogen consumption at this time is y _i , the error e _i is obtained by e _i = y _i −y _i (bar), and the (n + 1) th correction e _{i + 1} is e _{i + 1} (bar). = E _i (bar) + ae _i
However, a is a real number of 0 <a ≦ 1.
By introducing this error e _i (bar), the prediction matches the actual hydrogen consumption in the near future.
[0029]
For example, when the processing amount of kerosene desulfurization equipment or the properties of raw materials change, the hydrogen consumption prediction model section predicts the total hydrogen consumption required by the kerosene desulfurization equipment, and further supplies the PL hydrogen supply (standard PL hydrogen Supply amount).
Even if this PL hydrogen supply amount (standard PL hydrogen supply amount) is supplied, the hydrogen purity in the apparatus may not be maintained at 80% because the purity of PL hydrogen changes. Therefore, a correction amount (PL hydrogen supply amount to be added or subtracted) for maintaining the purity at 80% with respect to the standard PL hydrogen supply amount is calculated using fuzzy inference. The fuzzy control rule is shown in FIG.
[0030]
In creating this fuzzy control rule, it is necessary to take into account the time delay and non-linearity of the effect on the equipment purity due to the change in the PL hydrogen supply amount. Therefore, based on the data in the transient state, a transient state hydrogen consumption model is created using a neural network, and a fuzzy control rule is created based on the characteristics of this model.
[0031]
In this control rule, the center line of the row is the hydrogen purity of the kerosene oil desulfurizer, which is 80% of the target purity. Therefore, if the hydrogen purity of the kerosene desulfurization unit is lower than 80%, the supply amount of PL hydrogen will be reduced.
That is, when going to the right from the center, the supply amount of PL hydrogen is reduced from the center value. In this control rule, the center line of the row means that the hydrogen purity of PL hydrogen does not change.
[0032]
Therefore, if the hydrogen purity of PL hydrogen in the kerosene desulfurization unit is improving, the supply amount of PL hydrogen will be increased. For example, if there is room for hydrogen purity in the kerosene oil desulfurization device (hydrogen purity in the kerosene oil desulfurization device exceeds 80%) and there is no change in the PL hydrogen purity, the PL hydrogen supply should be Will increase a little.
In this way, the feed amount of PL hydrogen when the purity of PL hydrogen changes is controlled in a feed-forward manner based on the fuzzy control rules.
While performing such hydrogen purity control, pressure control with quick response changes the supply amount of HY hydrogen and always maintains the apparatus pressure at 50 kg / cm ² .
[0033]
The purity control of the hydrogen for the heavy oil desulfurization apparatus 3 is also performed by the same purity control unit 10 as described above.
[0034]
When the sum of PL hydrogen required for purity control in kerosene desulfurization equipment and PL hydrogen required for purity control in heavy oil desulfurization equipment exceeds the amount of PL hydrogen actually generated, If PL hydrogen is used in accordance with purity control, the amount of HY hydrogen consumed is extremely reduced, which may break the lower limit of device restrictions of the hydrogen generator. Therefore, a management control unit 15 that determines the priority order of the hydrogen consuming devices that use PL hydrogen and instructs the upper and lower limits of the use of PL hydrogen is provided.
[0035]
For example, if priority is given to the supply amount of PL hydrogen to the heavy oil desulfurization device 3, the management control unit 15 uses the PL hydrogen amount required for the purity control of the heavy oil desulfurization device as the upper limit of the heavy oil desulfurization device. The purity control unit on the side of the desulfurization unit is instructed, and the upper limit of the purity control unit of the kerosene desulfurization unit requires (the amount of PL hydrogen actually generated)-(purity control of the heavy oil desulfurization unit) Specify the amount of PL hydrogen.
And each purity control part 10 and 10 is controlled to supply PL hydrogen within the range.
[0036]
Although the case where hydrogen gas is used as the gas has been described in the above embodiment, the present invention can be applied to balance control between gases other than hydrogen gas, for example, off-gas generated in a plant, fuel oil, and fuel gas. That is.
[0037]
【The invention's effect】
According to the gas balance control device according to claims 1 and 2 configured as described above, the purity control of the gas can be performed automatically and more accurately.
Further, according to the gas balance control device of the third aspect , the distribution of the low-purity and inexpensive gas and the high-purity and expensive gas can be optimized according to the conditions of the consuming device.
According to the gas balance control device of the fourth aspect, even when there are a plurality of consumption devices, appropriate control can be performed according to the conditions of the fuel consumption device.
Moreover, according to the gas balance control apparatus which concerns on Claim 5 , the cheap low purity hydrogen gas which generate | occur | produces from a catalytic reformer can be distributed appropriately and supplied.
[Brief description of the drawings]
FIG. 1 shows a block diagram of a system for carrying out hydrogen gas balance control according to an embodiment of the present invention.
FIG. 2 is a detailed block diagram of a purity control unit in FIG.
FIG. 3 is an explanatory diagram of a model creation example in a steady state hydrogen consumption prediction model of a purity control unit.
FIG. 4 is a table showing an example of a fuzzy control rule in a fuzzy control unit of a purity control unit.
[Explanation of symbols]
1 catalytic reformer (PL)
2 Hydrogen production equipment (HY)
3 Heavy oil desulfurization equipment (RH)
4 Kerosene oil desulfurization equipment (2DH)
10 Purity Control Unit 11 Hydrogen Consumption Prediction Model Unit 11a Steady State Hydrogen Consumption Prediction Model Unit 11b Correction Unit 12 Fuzzy Control Unit

Claims (5)

In an energy supply system that mixes multiple gases and supplies them to a gas consuming device,
A purity control unit for controlling the gas purity in the gas consuming apparatus to be a predetermined purity;
A gas balance control device comprising: a pressure control unit that controls the gas pressure in the gas consuming device to be a predetermined pressure ,
The purity control unit is
A gas balance control characterized by obtaining a steady state gas consumption prediction amount, compensating for the difference between the predicted gas consumption amount and the actual gas consumption amount, and controlling the change in the purity of the supply gas by fuzzy control apparatus. The fuzzy control is
2. The gas balance control apparatus according to claim 1, wherein the control is performed according to a fuzzy control rule created based on characteristics of a transient gas consumption prediction model created based on data of a transient state obtained in advance. The plurality of gases are a high purity gas and a low purity gas having different purities,
The purity control unit supplies the low purity gas while controlling the gas purity so that the gas purity in the gas consuming apparatus becomes a predetermined purity,
3. The gas balance control device according to claim 1, wherein the pressure control unit supplies the high-purity gas while controlling the pressure in the hydrogen consuming device to be a predetermined pressure. If there are multiple gas consuming devices,
4. The gas balance control device according to claim 1, further comprising a management control unit that determines a priority order of the gas consuming devices that supply the gas, and performs gas distribution control based on the priority order. The gas is hydrogen gas;
5. The gas balance control according to claim 1, wherein the high purity gas is a hydrogen gas generated from a hydrogen production device, and the low purity gas is a hydrogen gas generated from a catalytic reforming device. apparatus.

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