JPH0510681B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a hydrogen demand fluctuation control device that can effectively respond to changes in the hydrogen demand of a hydrogen generator used in an oil refinery.

<Prior Art> In petroleum refining, hydrodesulfurization, hydrocracking, etc. of heavy oil have come to be carried out on a large scale, resulting in a rapid increase in hydrogen consumption. For this reason, various hydrogen production methods have been developed, and currently
Steam reforming (steam reforming) methods that use LPG or naphtha as raw materials have become mainstream. This produces hydrogen by reacting raw material hydrocarbons with steam at around 800°C using a catalyst.

FIG. 3 is a block diagram showing the configuration of a conventional hydrogen production apparatus.

10 is a hydrogen generator, to which LPG as a raw material is supplied via a flow line 11. The flow rate line 11 is provided with a flow rate detection unit 12 and an operation valve 13, and a flow rate controller 1 is installed so that the flow rate set value SP ₁ is reached.
4 controls the flow rate of LPG. These components constitute a flow rate control system 15 that controls the flow rate of raw materials.

16 is a boiler, and boiler water is supplied via a flow line 17. The flow rate line 17 is provided with a flow rate detection section 18 and an operation valve 19, and the flow rate of the boiler feed water is controlled by a flow rate controller 20 so as to reach a flow rate set value _SP2 . These components constitute a flow rate control system 21 that controls the flow rate of boiler feed water. A fuel line 2 supplies fuel to the boiler 16.
2 is provided. Steam generated in the boiler 16 is supplied to the hydrogen generator 10 via a flow line 23. The flow rate line 23 includes a flow rate detection section 24.
A control valve 25 is provided, and a flow rate controller 26 controls the steam flow rate so that the flow rate setting value _SP3 is reached. The flow rate detection section 24, the operation valve 25, and the flow rate controller 26 constitute a flow rate control system 27.

The hydrogen generator 10 mixes LPG supplied from the flow line 11 and steam supplied from the flow line 23 and heats the mixture under a catalyst to cause a chemical reaction and generate hydrogen. The generated hydrogen is supplied to the downstream hydrogen purification device 28 and purified into high quality hydrogen. In addition, the chemical reaction that generates hydrogen generates off-gas with low hydrogen content, which is discharged to the flare via the flow line 30.

In the above configuration, the hydrogen generator needs to supply hydrogen that matches the hydrogen demand of the load, but this hydrogen demand is set by the operator as a flow rate setting value in the flow controller 14, and the hydrogen generator is set accordingly. The operator sets the flow rate setting values SP ₃ and SP ₂ so that the steam and boiler feed water will be the same.
In this case, if the hydrogen generator 1 is not operated properly,
During the reaction at 0, carbon is precipitated which causes various troubles. However, since the minimum steam/carbon ratio that does not cause carbon precipitation corresponding to the reaction temperature and pressure in the equilibrium state is known, the operator can monitor it to achieve a steam/carbon ratio higher than this to meet the LPG amount. This problem can be solved by controlling the amount of steam. In this case, the boiler feed water is also adjusted according to the amount of steam.

In addition, even when changing the hydrogen demand, the flow rate set value is always set higher than the minimum steam/carbon ratio.
Since it is necessary to change SP ₁ , SP ₂ , and SP ₃ , the operator takes a long time to make the changes.

<Problems to be solved by the invention> However, in such conventional hydrogen generators, hydrogen-containing off-gas is released into the flare, which causes loss and reduces efficiency, and even during steady operation, the operator has to control the LPG flow rate. Since the steam flow rate is manually controlled, the steam/carbon ratio fluctuates and is not constant. Therefore, the steam/carbon ratio must be maintained a little high, resulting in steam loss. Furthermore, even when the hydrogen demand changes, the steam/carbon ratio does not change. Since the motor must be operated while always maintaining the value higher than a predetermined value, the driving operation requires time and is prone to operational errors.

<Means for solving the problems> In order to solve these problems, the present invention has the following features:
hydrogen generating means 10 for generating hydrogen using hydrocarbons as raw materials and steam in the presence of a catalyst;
A flow rate control means 15 that controls the flow rate of the hydrocarbon to be supplied to the previous hydrogen generation means given the set flow rate Q _SH , and a hydrogen flow rate Q contained in the flow rate of the previous hydrocarbon using the correction value AD ₁ . Hydrogen flow rate calculation means 32 that calculates _H , and hydrogen demand amount control means 33 that sets the previously set flow rate Q _SH to the previous flow rate control means so that this hydrogen flow rate Q _H becomes the specified hydrogen demand amount SP ₄ .
, a steam flow rate control means 26 for controlling the flow rate of the steam to be supplied to the hydrogen generation means, and a means for switching the set flow rate based on the steam/carbon ratio calculated from the flow rates of the hydrocarbon and the steam. The steam/carbon ratio control means 35 sets the flow rate setting value SP ₆ to the previous steam flow rate control means via SW ₂ , and when increasing the specified hydrogen demand SP ₄ , it sets it to the previous hydrocarbon flow rate change. The previous switching means SW ₂ is switched in advance to set the previous steam flow rate setting value SP ₆ as a larger setting value SP ₆ ' in the previous steam flow rate control means 26, and the previous specified hydrogen demand SP ₄ is set. When decreasing it, the previous hydrocarbon flow rate is changed prior to the previous steam flow rate change, and the smaller hydrogen demand amount is set as the previous designated hydrogen demand amount SP ₄ ' in the hydrogen demand amount control means 33. This configuration includes demand amount changing means 40.

<Function> During steady operation, the hydrogen flow rate is calculated from the flow rate of hydrocarbons in the flow rate detected by the flow rate control means, and the flow rate control means is set so that the specified hydrogen demand is achieved. The steam/carbon ratio is calculated from the flow rate, and the steam flow rate control means is set to a predetermined steam flow rate for automatic operation.When changing the hydrogen demand amount, the demand amount changing means follows a predetermined change procedure. Automatically operates by changing the hydrocarbon flow rate and steam flow rate.

<Example> Hereinafter, an example of the present invention will be described based on the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention. Note that parts having the same functions as those shown in FIG. 3 are designated by the same reference numerals, and their explanations will be omitted as appropriate.

Off gas from the hydrogen generator 10 is supplied through the flow line 30
It is collected at the connection point 31 of the flow rate line 11 via the LPG flow rate line 11, added to the LPG flow rate supplied as a raw material, and sent to the flow rate detection section 12.

The flow rate Q _L detected by the flow rate detection unit 12 is input to the hydrogen amount calculation unit 32 and is auxiliary data that is input separately.
The hydrogen flow rate Q _H included in the flow rate Q _L is calculated using AD ₁ and output to the hydrogen demand control controller 33 . Auxiliary data AD ₁ is, for example, LPG temperature, pressure,
This includes the hydrogen content of off-gas.

The hydrogen demand flow rate is set to the hydrogen demand control controller 33 from the outside as a set value SP ₄ via the switch SW ₁ , and the hydrogen demand control controller 33 sets the flow rate controller 14 to the set value SP ₄ . Set flow rate Q _SH
Output.

In this manner, the flow rate in the flow line 11 is controlled to the required hydrogen flow rate.

34 is a steam/carbon ratio calculation section, which includes the flow rate Q _L detected by the flow rate detection section 12 and the flow rate detection section 2.
The auxiliary data such as the steam flow rate Q _S detected in step 4 and the LPG component are input, and the steam/carbon ratio calculation is executed. This calculation result is input to the steam/carbon ratio control controller 35. On the other hand, the optimum steam/carbon ratio is set as a set value SP ₅ in the steam/carbon ratio control controller 35, and the steam flow rate that achieves this ratio is set in the flow controller ₂₆ via the switch SW2. Set as setting value SP ₆ .

Therefore, the flow rate of steam in flow line 23 is controlled to provide the required steam/carbon ratio.

With this configuration, LPG is used during steady operation.
while controlling the supply amount to the target demand amount.
In response to LPG flow rate fluctuations, the steam flow rate is controlled to follow these fluctuations at a predetermined steam/carbon ratio.

Next, the case of changing the hydrogen demand amount will be explained. Even in this changing process, it is necessary to control the steam/carbon ratio so that it is always greater than a predetermined value.

The set value of the hydrogen demand controller 33 is set via switch SW ₁ , and the set value SP ₄ ' is sent to the timer 36 and the first-order delay circuit.
From LAG1, the set value of the flow rate controller 26 is sent to the set value SP through switch SW ₂ , and the set value SP ₆ ' is sent to the timer 37, and the set value of the flow rate controller 20 is sent to the set value SP from the first-order delay circuit LAG2 through switch SW ₃ . ₂ ' is timer 38,
Each is set from the first-order delay circuit LAG3.

Reference numeral 39 is a setting device for setting changes in hydrogen demand, and is set by the operator. The change sequence unit 40 is activated by setting the hydrogen demand amount to the setting device 39, and the timer 36 is activated according to this sequence.
The set value SP ₄ ' is sent to the hydrogen demand controller 33 via
The set value SP ₆ ′ is changed to the flow rate controller 26 via the steam optimum amount calculation unit 41 and the timer 37, and the set value SP ₂ ′ is changed to the flow rate controller 20 via the boiler optimum amount calculation unit 42 and the timer 38. It is set according to the procedure in the sequence section 40. The operations and sequence procedures of each of these parts are executed by a microcomputer having read-on memory, random access memory, and a processor.

Next, this change procedure will be explained using the flowchart shown in FIG.

When changing the hydrogen demand amount, it is determined in steps whether this change loop is normal or not. If there is an abnormality, the alarm device ANN will issue an alarm to the outside, preventing the process from proceeding beyond the step, and if there is no abnormality, the process will proceed to the step. The step waits for loop change settings. In this step, it is determined whether the change range of the hydrogen demand amount is within the minimum change range or the maximum change range. If the change exceeds the predetermined range, the alarm ANN will issue an alarm, and the process will return to the step to wait until another change is made. If the change width is within the predetermined range, the process moves to step.

In this step, a decision is made whether to increase or decrease the hydrogen demand. this is,
This is because the steam/carbon ratio must always be kept larger than a predetermined value, so the operating procedure changes depending on whether it is increased or decreased.

If the hydrogen demand is to be increased, proceed to step. In step, the steam flow rate corresponding to the hydrogen demand is calculated by the steam optimum amount calculation section 41,
The set value SP ₆ ' is set in the flow rate controller 26 through the first-order delay circuit LAG2 and the switch _SW2 . After determining whether the timer 37 has timed up (step), it is determined whether the steam flow rate is within a predetermined deviation. The decision in this step is to wait for this period to elapse, since changing process parameters requires time for the process to respond to the change.

Next, the process moves to step, where the boiler water supply and hydrogen flow rates are calculated, and the hydrogen demand control controller 33 and flow rate controller switches SW ₁ and SW are sent through the primary delay circuits LAG 1 and ₃ to the switches SW ₁ and SW 3. ₃ , hydrogen demand control controller 33, flow rate controller 20
are set as set values SP ₄ ′ and SP ₂ ′, respectively.
After determining whether the timer 36, 38 has timed up (step), it is determined whether the flow rates of boiler feed water and hydrogen are within a predetermined deviation or not. is finished and normal operation begins.

In the above procedure, the steam flow rate is increased in advance in step ~, and then the LPG flow rate and the accompanying boiler feed water are increased in step ~. In this way the steam/carbon ratio is always kept above a predetermined value.

On the other hand, when the hydrogen demand is to be reduced, the hydrogen flow rate is first reduced as shown in steps '-' and '-', and after that the steam flow rate is reduced, and then the process moves to the termination process '. Here, '~' indicate the processing corresponding to ~, respectively. By following such a procedure, the steam/carbon ratio is always maintained greater than a predetermined value.

<Effects of the Invention> As explained above in detail with the examples, according to the present invention, appropriate control corresponding to hydrogen demand is performed, so overproduction is suppressed, flare loss is recovered, and efficiency is improved. Since the steam/carbon ratio can be controlled to maintain an appropriate ratio, the amount of steam can be used effectively and energy can be saved.
In addition, by monitoring the steam/carbon ratio, abnormalities in process conditions can be detected early, and changes in hydrogen demand can be made with just a start-up operation. It saves money and labor, and since the operator can change the hydrogen flow rate trend record simply by monitoring it, it prevents erroneous operation, and it is possible to force a stop in case of an emergency, which improves safety, etc. There are various effects.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention;
FIG. 2 is a flowchart showing the procedure for changing the hydrogen demand amount in FIG. 1, and FIG. 3 is a block diagram showing the configuration of a conventional hydrogen production apparatus. 10...Hydrogen generator, 15, 21, 27...Flow rate control system, 16...Boiler, 32...Hydrogen amount calculation unit, 3
3...Hydrogen demand controller, 34...Steam/carbon ratio calculation unit, 36, 37, 38...Timer, 39...Setter,
40... Change sequence section, 41... Steam optimum amount calculation section, 42... Boiler feed water optimum amount calculation section.

Claims (1)

[Claims] 1 Hydrogen generation means 10 for generating hydrogen using hydrocarbons as raw materials and steam in the presence of a catalyst
, a flow rate control means 15 that is given a set flow rate Q _SH and controls the flow rate of the hydrocarbon supplied to the hydrogen generating means, and a flow rate control means 15 that controls the flow rate of the hydrocarbons supplied to the hydrogen generation means, and a flow rate control means 15 that controls the flow rate of hydrogen contained in the flow rate of the hydrocarbons using the correction value _{AD 1} . a hydrogen flow rate calculation means 32 for calculating the hydrogen flow rate; a hydrogen demand amount control means 33 for setting the set flow rate Q _SH in the flow rate control means so that the hydrogen flow rate Q _H becomes the designated hydrogen demand amount _SP 4; The steam flow rate control means 26 controls the flow rate of the steam supplied to the steam flow rate control means 26, and the steam flow rate control means ₂₆ controls the steam flow rate through the switching means SW2, which sets a set flow rate based on the steam/carbon ratio calculated from the flow rates of the hydrocarbon and the steam. a steam/carbon ratio control means 35 for setting a flow rate set value SP ₆ in the means; and when increasing the specified hydrogen demand amount SP ₄ , switching the switching means SW ₂ prior to changing the flow rate of the hydrocarbon; Steam flow setpoint SP ₆ larger setpoint
When SP ₆ ' is set in the steam flow rate control means 26 and the specified hydrogen demand amount SP ₄ is to be decreased, the flow rate of the hydrocarbon is changed prior to changing the flow rate of the steam, and the flow rate is sent to the hydrogen demand amount control means 33. A hydrogen demand fluctuation control device characterized by comprising: demand amount changing means 40 for setting a smaller hydrogen demand amount as the specified hydrogen demand amount SP ₄ ′.