JPH04300203A - Control of inert gas purification device - Google Patents

Abstract

PURPOSE:To stabilize the operation of the subject device by determining the flow volume of an inert gas passing through a catalyst tank as a function of the total volume of oxygen gas fed into an inert gas purification device. CONSTITUTION:In an inert gas purification device for adding hydrogen gas 5 to an inert gas 1 containing oxygen gas, reacting the oxygen gas in the inert gas with the added hydrogen gas and removing the oxygen gas as the resultant water, the following means is adopted. The flow volume 32 of the inert gas fed in an inert gas purification device and the concentration 31 of the oxygen gas in the inert gas are detected, respectively, and the total volume of the fed oxygen gas is computed 33 from the detected flow volume and the oxygen concentration. The flow volume of the inert gas passing through the catalyst tank 6 is computed on the basis of the computed total volume of the oxygen gas. The computed result is inputted as the setting value of a controller 34 for detecting and controlling 36, 35 and 23 the flow volume of the inert gas passing through the catalyst tank 6, and the control valve 23 of an inert gas compressor 3 is controlled by the output of the controller 34.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is an inert gas purification device, such as an argon purification device, which reacts oxygen contained in an inert gas with hydrogen and removes it in the form of moisture to obtain an oxygen-free gas. The present invention relates to a control method.

0002

2. Description of the Related Art An example of a conventional inert gas purification apparatus of this type is described in Japanese Patent Application Laid-open No. 77539/1983.

In FIG. 3, crude argon gas from, for example, a crude argon rectification column (not shown) is fed through a pipe 1, passes through a pipe 2, and is sent to an argon blower 3 to meet the pressure required for the operation of the apparatus, for example. Increase the pressure to 1kg/cm2G,
After mixing the hydrogen gas supplied from the pipe 5 in the pipe 4,
Oxygen and added hydrogen in the crude argon gas undergo a reaction of 2H2+O2→2H2O in the palladium catalyst tank 6, and are cooled by cooling water supplied from the pipe 9 in the argon precooler 8 via the pipe 7. Moisture generated during the reaction is condensed and removed from the drain trap 10 in the form of drain.

On the other hand, argon gas is passed from pipe 11 to pipe 12 to a dehumidification tower 13 where moisture is almost completely removed.
4 to subsequent equipment such as an argon rectification column (not shown).

The reaction in the palladium catalyst tank 6 described above is an exothermic reaction, and the amount of heat generated is proportional to the absolute amount of oxygen in the crude argon gas. When the absolute amount of oxygen is large, the amount of heat generated by the reaction is large, and when it is small, The amount of heat generated by the reaction is also small.

On the other hand, the reaction temperature in the palladium catalyst tank 6 usually needs to be maintained at around 250 to 300°C during operation; if the temperature rises above this, the equipment will be in a dangerous state, and conversely, if it falls below this temperature, the reaction will occur. may be insufficient.

In order to prevent an abnormal rise in reaction temperature, the capacity of the argon blower 3 is selected to be, for example, about 1.5 to 3.0 times the amount of crude argon gas supplied from the pipe 1, that is, the processing capacity of the apparatus. , a bypass circuit consisting of a pipe 15, an automatic control valve 16, and a pipe 17 is provided, and a pressure regulator 18 is installed. By decreasing the amount of argon gas and increasing the opening degree when the amount is low, the amount of bypass is automatically controlled so that the amount of bypass is always equal to the capacity of the argon blower 3 minus the amount of crude argon gas supplied.

With this configuration, the amount of argon gas passing through the palladium catalyst tank 6 can be set regardless of the amount of crude argon gas fed through the pipe 1. Therefore, the amount of heat removed from the palladium catalyst tank 6 is inevitably determined, and by balancing it with the amount of heat generated by the reaction, the reaction temperature of the palladium catalyst tank 6 becomes constant.

However, when the absolute amount of oxygen contained in the crude argon gas fed through the pipe 1 increases,
The calorific value increases, and when the amount of argon gas passing through the palladium catalyst tank 6 is constant, the proportion of heat carried away by the passing argon gas decreases compared to the calorific value. Therefore, the reaction temperature of the palladium catalyst tank 6 inevitably rises.

On the other hand, when the absolute amount of oxygen contained in the crude argon gas fed through the tube 1 decreases, the calorific value also decreases, and when the amount of argon gas passing through the palladium catalyst tank 6 is constant, , the proportion of heat carried away by the passing argon gas increases compared to the calorific value. Therefore, the reaction temperature of the palladium catalyst tank 6 inevitably decreases.

[0011] As a countermeasure against this problem, the prior art provides a pipe 19, an automatic control valve 23, and a pipe 21 in the argon blower 3, and also provides a temperature controller 24 in the palladium catalyst tank 6.
If the temperature drops below the set value, the automatic control valve 23
The bypass flow rate of the argon blower 3 flowing in the line from the pipe 19 to the automatic control valve 23 to the pipe 21 was increased. As a result, the flow rate of argon gas flowing out from the palladium catalyst tank 6 is reduced, so the amount of heat carried away by the argon gas is reduced, and a drop in temperature can be prevented. Conversely, if the temperature rises above the set value, the opening degree of the automatic control valve 23 is automatically reduced by the action of the temperature controller 24, and the argon flowing in the line from the pipe 19 to the automatic control valve 23 to the pipe 21 is The bypass flow rate of blower 3 decreases. As a result, the flow rate of argon gas flowing out from the palladium catalyst tank 6 increases, so the amount of heat carried away by the argon gas increases, making it possible to prevent a rise in temperature.

0012

[Problems to be Solved by the Invention] In the above-mentioned prior art, the temperature of the palladium catalyst tank is controlled by feedback using a temperature controller, and on the other hand, the specific heat of the palladium catalyst is quite large, and the amount of palladium catalyst itself is large. Not only is the response to control extremely slow, making it difficult to adjust control parameters, but it also sometimes causes significant hunting and loss of control, and in the worst case scenario, the protection device is activated and the equipment is forced to stop. That's what happened.

An object of the present invention is to provide a control method for an inert gas purification apparatus that eliminates the drawbacks of the above-mentioned prior art and allows stable operation.

[0014]

[Means for solving the problem] In order to achieve the above object, hydrogen gas is added to an inert gas containing oxygen, and the oxygen in the inert gas and the added hydrogen are converted into 2H2+O2→2 in a catalyst tank.
In an inert gas purification system that removes oxygen in the inert gas in the form of water by performing a H2O reaction, the flow rate passing through the catalyst tank is a function of the total amount of oxygen supplied to the inert gas purification system. It's up to you to decide.

[0015]

[Effect] The amount of heat generated in the palladium catalyst tank is determined by the total amount of oxygen supplied to the inert gas purification equipment, and the amount of heat removed from the palladium catalyst tank is determined by the amount and temperature of the gas passing through the catalyst tank. By determining the flow rate of oxygen as a function of the total amount of oxygen supplied to the inert gas purifier, the temperature of the palladium catalyst tank can be determined uniquely from the balance between the calorific value in the palladium catalyst tank and the amount of heat carried away by the passing gas. It is to be determined.

[0016]

[Embodiment] An embodiment of the present invention will be explained below with reference to FIG.

Since the operation of the apparatus shown in FIG. 1 is the same as that of the prior art, a detailed explanation will be omitted, and the main points of the present invention will be explained in detail. Note that the same parts as in FIG. 3 are indicated by the same symbols.

In FIG. 1, crude argon gas from, for example, a crude argon rectification column (not shown) is fed through a pipe 1, and the total amount of oxygen in the crude argon gas is measured with an oxygen analyzer 31. Based on the oxygen concentration in the crude argon gas and the crude argon gas flow rate measured by the flow meter 32, the calculator 3
3, it is configured to be determined by calculating (total oxygen amount=crude argon gas flow rate×oxygen concentration in crude argon gas).

On the other hand, the flow rate of the argon gas entering the palladium catalyst tank 6 is measured by a flow meter 36, and is compared and controlled by a controller 35 with a set value from a calculator 34, so that, for example, the measured value is higher than the set value. If the argon blower 3 is large, the automatic control valve 23 is operated in the opening direction to increase the bypass air volume of the argon blower 3.
, the flow rate of the argon gas entering the palladium catalyst tank 6 decreases, and conversely, if the measured value is smaller than the set value, the automatic control valve 23 is operated in the closing direction. By reducing the bypass air volume of the argon blower 3, the processing capacity of the argon blower 3 appears to be increased, and the flow rate of the argon gas entering the palladium catalyst tank 6 is configured to increase.

The computing unit 34 is configured to output a function (for example, multiplied by a certain ratio) of the total oxygen amount determined by the computing unit 33 to become the setting value of the controller 35.

Here, the amount of reaction heat generated in the palladium catalyst tank 6 is proportional to the total amount of oxygen supplied to the palladium catalyst tank 6, and the amount of heat taken out from the palladium catalyst tank 6 flows through the palladium catalyst tank 6. As mentioned above, it is proportional to the product of the argon gas flow rate and the temperature.

Furthermore, the following relational expression holds true here.

Amount of reaction heat generated in the palladium catalyst tank 6 =K
1×WO2 ---(1) Amount of heat taken out from palladium catalyst tank 6 = K2×WAR×T---(
2) However, K1, K2: Proportional constant WO2: Total amount of oxygen supplied to the palladium catalyst tank 6 WAR: Argon gas flow rate flowing through the palladium catalyst tank 6 T: Reaction temperature of the palladium catalyst tank 6 Generated in the palladium catalyst tank 6 The reaction heat amount and the heat amount taken out from the palladium catalyst tank 6 are equal (1) and (
2) The following relational expression holds true.

[0024] K1×WO2=K2×WAR×T --
-(3)T=(WO2/WAR)×(K1/K2)--
-(4) Equation (4) shows that once the ratio of the total amount of oxygen supplied to the palladium catalyst tank 6 to the flow rate of the argon gas flowing through the palladium catalyst tank 6 is determined, the reaction temperature of the palladium catalyst tank 6 is uniquely determined. This shows that the calculation unit 3
By setting the constant 4 to an appropriate value, constant temperature control becomes possible.

Further, in this embodiment, the total amount of oxygen supplied to the palladium catalyst tank 6 is determined by the flow rate of the crude argon gas supplied to the inert gas purification device and the oxygen concentration in the crude argon gas. However, as shown in another embodiment in FIG. 2, the total amount of oxygen supplied to the palladium catalyst tank 6 is determined by the flow rate of the crude argon gas flowing through the palladium catalyst tank 6 and the oxygen concentration in the crude argon gas. Needless to say, the same effect can be obtained by doing so. In addition, in the case of this embodiment, the number 32 flowmeter is omitted, and the number 36 is omitted.
It is also possible to use it as a flow meter.

In each of the embodiments, the installation location of the argon gas flow meter flowing through the palladium catalyst tank 6 was explained on the inlet side of the palladium catalyst tank 6, but it was explained that the flowmeter was installed in the part from the pipe 7 to the pipe 11 on the outlet side. It is clear that similar effects can be obtained.

Furthermore, when installing between the bypass pipe 19 of the argon blower 3 and the hydrogen supply pipe 5, there is no problem as long as the amount of hydrogen to be supplied and mixed is corrected, and in reality, the amount of hydrogen is smaller than the total amount. The amount is small and can be safely ignored.

[0028] Also, the bypass piping 1 of the argon blower 3
The flow rate of the argon gas flowing through the palladium catalyst tank 6 can also be determined by installing a flow meter at the part 9 or 21 and subtracting it from the air volume of the mechanical capacity of the argon blower 3. Furthermore, according to this embodiment, from the ratio of air volume,
The flowmeter can be smaller than the above-mentioned installation location.

In addition, the flow rate of the argon gas flowing through the palladium catalyst tank 6 can be determined by installing a flow meter at each branch point of this system diagram and performing addition and subtraction, and it is possible to implement the present invention. This method is not very practical.

[0030]

Effects of the Invention As explained above, according to the present invention, since it does not rely on process feedback control, there is no need to adjust control parameters, which was difficult, and there is no temperature hunting, which naturally maintains a constant temperature. reached and stable operation can continue.

[Brief explanation of drawings]

FIG. 1 is a system diagram of an inert gas purification apparatus showing one embodiment of the present invention.

FIG. 2 is a system diagram of an inert gas purification apparatus showing another embodiment of the present invention.

FIG. 3 is a system diagram of an inert gas purification apparatus showing an example of the conventional technology.

[Explanation of symbols]

1, 2, 4, 5, 7, 9, 11, 12, 14, 15, 1
7, 19, 21... Pipe, 3... Argon blower, 6... Palladium catalyst tank, 8... Argon precooler, 10... Drain trap, 13... Dehumidification tower, 16, 23... Automatic control valve, 1
8... Pressure controller, 24... Temperature controller, 31... Oxygen concentration detector, 32, 36... Flow rate detector, 33, 34... Arithmetic unit,
35...Flow rate controller.

Claims (5)

[Claims] Claim 1: Inert gas purification in which hydrogen gas is added to an inert gas containing oxygen, and the oxygen in the inert gas is reacted with the added hydrogen in a catalyst tank to remove the oxygen in the inert gas as water. 1. A method of controlling an inert gas purification apparatus, characterized in that the flow rate passing through the catalyst tank is controlled as a function of the total amount of oxygen supplied to the catalyst tank. Claim 2: An inert gas compressor (hereinafter referred to as a compressor) equipped with an automatic bypass control valve (hereinafter referred to as a control valve) and a catalyst tank, which adds hydrogen gas to an inert gas containing oxygen. In an inert gas purification device that removes oxygen in the inert gas as moisture by reacting oxygen in the inert gas with added hydrogen in a catalyst tank, the inert gas supplied to the inert gas purification device The flow rate of the inert gas and the oxygen concentration in the inert gas are respectively detected, and the total amount of oxygen to be supplied is calculated based on the detected flow rate of the inert gas and the oxygen concentration in the inert gas. Calculate the flow rate that should pass through the catalyst tank from the total amount of oxygen, input the calculation result as a setting value of a control device that detects and controls the flow rate that passes through the catalyst tank, and control the control valve with the output from the control device. A method for controlling an inert gas purification device, characterized by: Claim 3: An inert gas compressor (hereinafter referred to as a compressor) equipped with an automatic bypass control valve (hereinafter referred to as a control valve) and a catalyst tank, which adds hydrogen gas to an inert gas containing oxygen. In an inert gas purification device that removes oxygen in the inert gas as moisture by reacting oxygen in an inert gas with added hydrogen in a catalyst tank, the flow rate of the inert gas passing through the catalyst tank and the inert gas are Detects the oxygen concentration in the active gas,
The total amount of oxygen to be supplied is calculated from the detected flow rate of the inert gas and the oxygen concentration in the inert gas, and the flow rate to be passed through the catalyst tank is calculated from the calculated total amount of oxygen. A method for controlling an inert gas purification device, comprising inputting a calculation result as a setting value of a control device that detects and controls a flow rate passing through a catalyst tank, and operating a control valve using an output from the control device. 4. The inert gas purification apparatus according to claim 2 or 3, wherein the flow rate passing through the catalyst tank is detected by a flow meter provided at the inlet or outlet pipe of the catalyst tank. control method. 5. The flow rate passing through the catalyst tank is determined by calculation from the processing capacity of the compressor and a value detected by a flow meter provided in the compressor bypass piping.
Or the method for controlling an inert gas purification device according to claim 3.