JPH0634894B2 - Method of equalizing the constant air volume of the adsorber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] In the present invention, when the pressures of a plurality of cylinders of an adsorber (including a dryer) are equalized, the pressure of the cylinders to be equalized The present invention relates to a constant air flow equalizing method for controlling so that a gas of a constant air flow always flows in the process of increasing the pressure in a sequential manner.

[Conventional technology]

In the gas separation method by PSA (pressure fluctuation adsorption) method, when a plurality of adsorbers are pressure-equalized, and when an adsorber, a drier, etc. are used to remove carbon dioxide, water, etc., When equalizing the pressure of an adsorber or a drier, conventionally, a pressure equalizing valve provided between the cylinders is electromagnetically operated or manually operated to open the pressure gas into the cylinder to be pressure-equalized. .

[Problems to be solved by the invention]

However, when the pressure equalizing valve is suddenly opened, a large amount of gas initially flows because the pressure in the cylinder to be pressure-equalized is initially near atmospheric pressure and the pressure difference is large, but the pressure difference decreases over time. It became difficult to flow and had the following drawbacks.

At the beginning of the pressure equalization, a large amount of gas flows from the adsorption column in the adsorption step to the adsorption column in the pressure equalization step, so that the flow rate of the purified gas decreases, causing confusion in the downstream device or the supply destination.

As the pressure equalization progresses, it becomes difficult for gas to flow, and pressure equalization takes time.

Dynamic pressure is applied at the start of pressure equalization, which adversely affects the adsorbent, the cylinder body, and others.

And these problems occur similarly for all devices that perform adsorption separation, but in the air separation device, a large amount of gas flows at the beginning of pressure equalization, so the amount of air entering the rectification column decreases and the rectification is disturbed. Is happening. In particular, when argon is collected at the same time, the gas composition in the argon raw material gas extraction section in the middle stage of the upper column of the double rectification column fluctuates, causing a troublesome problem.

In order to eliminate such inconvenience, it is conceivable to install a flow meter such as an orifice on the downstream side of the balance valve and manually adjust the valve opening, but it is necessary for a person to operate the valve at all times during operation of the device. It is almost impossible to achieve perfection.

Therefore, the present invention reduces the turbulence given to the downstream gas supply destination by varying the supply gas amount from the start of pressure equalization to the end of pressure equalization, thereby increasing the yield of the apparatus and adjusting the flow rate from the pressure equalizing valve. An object of the present invention is to provide a method for equalizing the constant air volume of an adsorber, which eliminates the troublesomeness which has been caused by providing an orifice or the like on the downstream side of the balance valve, and further eliminates the mechanical problems that have been given to the adsorbent, the cylinder body, etc. To aim. Further, in the case of the air separation device, the turbulence that has been introduced into the rectification column is reduced, and in particular, the purpose is to improve the yield when collecting argon.

[Means for solving problems]

In order to solve the above problems, the present invention uses a plurality of adsorption cylinders, an adsorption step of supplying a raw material gas composed of a plurality of components under pressure to adsorb an adsorbed component, and an adsorption cylinder that has completed the adsorption step. And a desorption process for desorbing the adsorbed components to be adsorbed,
In a gas separation method by a PSA (pressure fluctuation adsorption) method in which a raw material gas is continuously separated by repeating alternately in each adsorption cylinder, and a raw material gas is supplied to air or a plurality of adsorption cylinders provided in a gas separation device. Is supplied under pressure,
Adsorption process for adsorbing moisture and impurities in the carbon dioxide tower, and impurities adsorbed in the adsorption column after the adsorption process (adsorbed components)
In the air or gas separation method of supplying the raw material gas to the rectifying column continuously by alternately repeating the desorption step of desorbing and liquefying in the rectifying column,
When the gas is introduced into the adsorption column after the desorption process from the adsorption column during the adsorption process to equalize the pressure of the adsorption column, the secondary pressure behind the balance valve is detected, and this is compared and calculated by the program setting device. In addition, the valve opening of the balance valve is automatically controlled so that the required Cv value corresponding to the secondary pressure is obtained, so that a constant amount of gas flows through the balance valve. To do.

[Work]

Therefore, when equalizing the pressure of the adsorber, a constant amount of gas always automatically flows to the side of the adsorption cylinder where the pressure should be equalized, regardless of the pressure of the adsorption cylinder to be equalized, and prevents disturbance to the entire device. You can

〔Example〕

FIG. 1 is a system diagram of an adsorption cylinder, in which adsorption is performed under pressure and desorption is performed at normal pressure.

An adsorbent is filled in the pair of adsorption cylinders 1 and 2,
The compressed raw material gas entering from the pipe 3 passes through the adsorption layer of the adsorption column 1 through the valve 4, and impurities such as water and carbon dioxide are adsorbed at this time, and the dehumidified body passes through the check valve 5 and rectifies from the pipe 6. It has been sent to the tower.

At this time, one of the adsorption cylinders 2 is in the process of regeneration, and the dehumidified body returned to normal pressure passes through the adsorption cylinder 2 in the reverse direction from the pipe 7 through the check valve 8 to absorb the water adsorbed in the adsorption layer. , While adsorbed components such as carbon dioxide are removed through the valve 9 through the pipe 10.

After the regeneration (desorption) is completed, the pressure in the adsorption cylinder 2 is equalized. This pressure equalization step is performed by opening the balance valve 11 and sending the compressed gas that has passed through the adsorption cylinder 1 to the adsorption cylinder 2 side. In this embodiment, at the time of this pressure equalization, a constant flow rate is always flowed regardless of the pressure of the cylinder to be pressure-equalized in the process of increasing the pressure from near atmospheric pressure to the working pressure, and the apparatus is not fluctuated.

An adsorber for adsorbing and removing moisture and carbon dioxide from raw material air will be described below by taking an air separation device of a type using an adsorber for removing impurities as an example. Raw air flow rate is 11,0
The pressure is 00 Nm ³ / h and the pressure is 30 kg / cm ² . About 30 kg / cm ² from one atmospheric pressure to the one adsorption cylinder 2 whose regeneration is finished.
The following table shows the calculation of each Cv value (flow coefficient) in the process of equalizing pressure up to. The suction cylinders 1 and 2 have a diameter of 1700 mm and a flow rate of 5200 mm, and if the pressure is equalized in 15 minutes, the flow rate Q will be 1095 m ³ / h.

As shown in this calculation, in order to make the gas flowing through the balance valve a constant air flow in the pressure equalizing step, the Cv value may be changed as shown in the above table. The Cv value is a flow coefficient when determining the valve aperture, and is expressed as a function of the valve passage area. Therefore, in order to secure the required area of the valve, a command may be given from the outside so as to obtain the Cv value in the above table.

That is, the air amount is 11,000 Nm ³ / h, the pressure is 30 kg / cm ² ,
When equalizing the pressure of the adsorber at a temperature of 5 ° C. and a switching cycle of 12 hours, the balance valve 11 has a minimum Cv value of 2.36 and a maximum Cv.
A valve with a value of 5.9 should be selected. If selected in this way, the flow rate will be remarkably reduced during pressure equalization, and the remarkable disturbance of the rectification state in the rectification column when collecting argon will be eliminated, and the device can be operated stably.

FIG. 2 shows an embodiment of the method of the present invention. The balance valve 11 is divided into two chambers by partitioning the inside of the valve box 22 with a diaphragm 23, the upper part is the working air pressure chamber 24, and the lower part is the gas inlet 2.
5 and the gas outlet 26 to form a gas flow chamber 27, and the diaphragm 23 is formed substantially at the center of the diaphragm 23.
The valve shaft 28 is vertically provided so as to move up and down according to the movement of the valve 23, and the valve element 29 can be opened and closed with respect to the valve seat 30 by the movement of the diaphragm 23.

The lower portion of the valve shaft 28 is connected to a balance rod 33 that is biased upward by a balance spring 32 attached to the valve box bottom portion 31, and the working air pressure chamber 24.
When the compressed air is sent to the valve 29,
Is closely closed to the valve seat 30.

The working air to the working air pressure chamber is the working air pressure introducing pipe 3
4 and the working air pipe 35, and the feeding amount of the working air is adjusted by connecting one end to the gas outlet 26 side and the other end of the pressure detecting pipe 36 for detecting the secondary pressure. Is connected to a program setting device 37 interposed between the working air pressure introducing pipe 34 and the working air pipe 35, so that the program setting device 37 detects the secondary pressure.

The program setting device 37 is a setting device that supplies air pressure for automatically opening the valve element 29 so that a constant flow rate flows during the balance time regardless of the secondary pressure within the determined balance time. It has the following functions.

Calculate the flow rate per unit time from the capacity of the adsorption column and the balance time.

The required Cv value for each pressure corresponding to the above flow rate is calculated.

Calculate the valve lift corresponding to the Cv value.

An operating pressure that gives a valve lift for flowing a constant flow rate for each pressure is sent to the operating air pipe 35.

With the above function, a constant air flow can be always sent to the side of the adsorption cylinder 2 where pressure should be equalized. Therefore, as shown in the table, the secondary pressure is made equal to the primary pressure while keeping the primary pressure constant. be able to.

〔The invention's effect〕

As described above, according to the present invention, the Cv value of the balance valve is obtained in advance so that a constant amount of gas always flows when the pressure of the adsorption cylinder is equalized, and the command of the valve operation amount is given so that the Cv value becomes the value. Since the valve opening is automatically controlled, a constant air flow can be always sent to the side of the adsorption cylinder to be pressure-equalized, and the primary pressure, that is, the pressure in the adsorption cylinder that delivers gas for pressure equalization, can be controlled. The pressure can be equalized while keeping the pressure constant. Therefore, the influence of the PSA (pressure fluctuation adsorption) separation device, the air separation device, the gas separation device, etc. on the device at the time of pressure equalization becomes very small. This effect is great especially when the demand for argon in the air separation device is high and the argon collecting operation is performed under severe conditions, and not only the yield but also the mental burden on the operator is reduced. Also,
The automatic control eliminates the trouble of adjusting the flow rate by the orifice or the like.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is a system diagram of an adsorption cylinder, and FIG. 2 is a sectional view for explaining an embodiment of a constant air flow equalizing method. 1, 2 ... Adsorption cylinder, 22 ... Valve box, 23 ... Diaphragm, 24 ... Working air pressure chamber, 25 ... Gas inlet, 26 ...
... Gas outlet, 27 ... Gas distribution chamber, 28 ... Valve shaft, 29 ...
... valve, 30 ... valve seat, 31 ... bottom, 32 ... balance spring, 33 ... balance rod, 34 ... operating air pressure introducing pipe, 35 ... operating air pipe, 36 ... secondary pressure Detector tube, 37 ... Program setting device

Claims (1)

[Claims] 1. An adsorption step of supplying a raw material gas composed of a plurality of components to a plurality of adsorption cylinders under pressure to adsorb an adsorbed component,
In the gas separation method in which the raw material gas is continuously separated by alternately repeating the desorption process of desorbing the adsorbed component adsorbed in the adsorption column after the adsorption process, the adsorption column after the desorption process is completed When the gas is introduced from the adsorption cylinder during the adsorption process to equalize the pressure of the adsorption cylinder, the secondary pressure behind the balance valve is detected, and this is compared and calculated by the program setting device and is equivalent to the secondary pressure. The valve opening of the balance valve is automatically controlled so as to obtain a required Cv value so that a constant amount of gas flows through the balance valve at all times. Pressure method.