JPH03131317A - Apparatus for minimizing fluctuation of continuous refining in pressure swing adsorption - Google Patents

Abstract

PURPOSE:To minimize the fluctuation of pressure and that of a flow rate in pressure swing adsorption continuously performing the refining of gas by setting the rising pressure of an adsorbing tower to predetermined pressure during a predetermined time and controlling the flow rate of raised pressure gas so as to perform continuous quantification. CONSTITUTION:An operation means 14 always continuously operates a raised pressure gas flow rate set value from the values read by respective reading means 11a-11c, 12, 13, 18, 19 and the pressure raising process setting time and pressure raising process advance time set according to an adsorbing process change over sequence program. A raised gas flow rate controller 15 compares the raised pressure gas flow rate set value operated by the operation means 14 with the raised pressure gas real flow rate read by a raised pressure gas flow rate reading means 16 and controls the opening degree of a flow rate control valve 17 so that the raised pressure gas real flow rate becomes same to the raised pressure gas flow rate set value. As a result, the fluctuation of pressure and that of a flow rate can be minimized without arranging a surge tank.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention applies pressure swing adsorption (hereinafter referred to as PSA) to J,
The present invention relates to a device that minimizes flow rate fluctuations and pressure horn fluctuations of purified gas in continuous purification of mixed gases.

(Background of the invention and prior art) Fluctuations in flow rate and pressure in continuous purification PSA are
This is because the pressurized gas flow rate is not continuous and constant, and PS
This occurs because the pressure is not increased to a predetermined level in the J push-off M-IJ cycle time of A.

The flow rate ff1 of the R pressure gas is adjusted by repeatedly performing recycling in which the pressure of the refined gas increases and the differential pressure of the adsorption tower performing the culm decreases as the pressure increases.
It is difficult to maintain a constant flow rate unless flow control is performed. However, even if a flow control valve is installed and controlled to maintain the pressurized gas flow rate at a constant flow rate, if the pressure is increased to a predetermined pressure earlier than the predetermined time, the pressurized gas will not flow and the pressure of the refined gas will change. The flow rate is h rfl-. In addition, if the pressure cannot be raised to a predetermined pressure within a predetermined time, the purified gas causes large flow rate fluctuations and pressure fluctuations due to the difference in the pressure of the purified gas at the next adsorption point.

However, increasing the pressure to a predetermined pressure in a predetermined time and finding a constant value of the gas flow rate requires changing the pressure of the purified gas, changing the adsorption process switching period of the adsorption tower, and changing the outside temperature. This was difficult because the pressurized gas m changes with changes in the adsorption amount of the adsorbent.

Accordingly, a device for controlling the pressurized gas flow rate is described, for example, in Japanese Patent Application No. 17fl 1983-63019. According to this device, the pressurized gas flow rate is controlled by using the H valve at the outlet of purified gas connected to the outlet of the adsorption tower as a control valve, so that part of the purified gas is pressurized during the pressurization process. (2) The flow is made to flow back to the adsorption tower where the culm is processed, and the control valve is operated according to changes in the pressure of the adsorption tower or the flow rate of the purified gas to maintain a constant flow rate of the pressurized gas.

(Problem to be Solved by the Invention) However, in the above-mentioned conventional device for controlling the pressurized gas flow h1, the control valve has the function of a switching valve that requires the flow resistance to be as small as possible in the adsorption process, and In the process, a small flow rate of pressurized gas is mixed with the primary side pressure of the flow rate control valve.
A GJ must have both the ability to adjust the flow rate at a constant rate even if the differential pressure on the next side differs significantly between the initial and final stages of the pressure increase process, but currently valves that satisfy both of the above functions are available. is difficult. Furthermore, since the pressurization process is not performed continuously, the flow rate of purified gas rapidly increases during the period when the pressurization gas process is not performed. Furthermore, since there is no method for increasing the pressure to a predetermined pressure in a predetermined time, pressure and flow rate fluctuations occur when switching between adsorption steps.

Therefore, when incorporating a PSA that performs continuous purification into a process that dislikes fluctuations in pressure and flow rate, pressure fluctuations and flow rate 17. Very large 4 to reduce fluctuations
Noge tanks are required, which increases the construction cost by 1~ and secures the site for installation, which becomes a big problem.

The present invention has been made in view of the above-mentioned problems faced by the prior art.The main purpose of the present invention is to increase the flow rate of pressurized gas to a predetermined pressure in a predetermined period of time, and In addition, by controlling the amount continuously, pressure fluctuations and flow rate fluctuations can be minimized without installing a surge tank in a PSA that continuously performs gas purification.

(Means for Achieving the Object) The technical means taken by the present invention to achieve the above object is to selectively select from a supplied mixed gas by pressure swing adsorption using three or more adsorption towers in cycles. A continuous purification device for mixed gas that removes one or more gas components and uses a part of the RR gas to boost the pressure. An adsorption tower pressure reading means that constantly reads the pressure and converts it into an electrical signal, a purified gas pressure reading means installed in the purified gas pipe (-J) that constantly reads the purified gas pressure and converts it into an electrical signal, and a purified gas pressure reading means that constantly reads the purified gas pressure and converts it into an electrical signal; A shielding agent depletion reading means is installed that constantly reads the adsorbent temperature from the processing surface gas temperature and converts it into an electrical signal, and the back pressure process is executed according to the adsorption tower process switching sequence program in pressure swing adsorption. boosting adsorption tower pressure reading means for identifying the adsorption tower to be used and reading the detected value of the pressure horn reading means of the adsorption tower by selecting from among the detected values of the pressure reading means of each of the adsorption towers; and the adsorption tower process switching. Sequence sp [21' culm progress time reading means that reads the pressure increase based on 1 gram and the culm progress time, the values read by each of the above reading means, the pressure increase process setting time and side pressure set in the adsorption process switching sequence program] A calculation means is installed to constantly and continuously calculate the pressurized gas flow rate setting value from the culm advancement time, and a pressurizing gas pipe is installed in the pressurizing gas pipe that branches from the purified gas pipe and connects to the adsorption tower that performs the first step of pressurizing. A pressurized gas flow rate reading means for reading the actual flow rate of gas and converting it into an electric signal, a flow rate control valve installed in the pressurized gas pipeline, and a pressurized gas flow rate setting value and pressurization calculated by the calculating means. a booster gas flow n1 regulator that compares the actual booster gas flow rate read by the gas flow reading means and controls the opening degree of the flow rate control valve so that the actual booster gas flow rate becomes the same as the back pressure gas flow setting value; It is equipped with.

(Function) In the device configured as below-F to minimize fluctuations in continuous purification in pressure swing adsorption, the pressurized gas flow rate setting value is set such that the pressurized gas flow rate is a constant amount and a predetermined pressure is reached in a predetermined time. is calculated, and the actual flow rate of the pressurized gas is controlled to match the set value. The calculation of the pressurized gas flow rate setting value is continuously performed from the beginning to the end of the pressurization process, including changing the adsorption tower process time, changing the purified gas pressure, changing the humidity of the gas before treatment, and changing the adsorbent. The p-pressure gas flow setting value is successively corrected in accordance with the regeneration process and temporal fluctuations in adsorption performance of the adsorbent due to outside temperature, etc., and the back pressure gas flow rate is continuously controlled based on the correction.

(Example> Embodiments of the present invention will be described below based on the drawings.

Figure 1 shows the suction Wt of the three towers A, B, and G? S (9a>
FIG. 1 is a diagram of a PSA apparatus that continuously purifies a mixed gas, that is, a pre-processing gas, using cycles of (9b) and (9C). .

It is clear from the figure that J, sea urchin, and each adsorption 325 (9a)
(9b) (9C) connect the lower part of each to the pre-treatment gas pipe (1)
To.

A part of the purified gas pipe (2) is connected to the pre-processing gas pipe (1) through the switching valve (5a> (5b) (5c) and the purified gas outlet switching valve (6a><6b) (6c), respectively. are arranged in parallel.

In addition, each adsorption tower (9a) (9b) (9c) is downstream of the pre-treatment gas inlet switching valve (5a) (5b) (5c) of the gas pipe (4) 1 pre-treatment gas pipe (1). The purified gas outlet switching valves (6a) (6b) of the purified gas pipe (2) communicate with the pressurized gas pipe (3) through the
) (6c) are connected via the upstream side.

The desorption gas pipe (4) and the promotion gas pipe (3) each have a desorption gas outlet switching valve (8a) (8b) for each adsorption tower (9a) (9b) (9c).
(8c) R pressure gas inlet switching valve (7a) (7b)
(7c) is set up. C1 This PSA device repeatedly performs the steps of adsorption, desorption (depressurization), and pressure increase by switching the switching valve.

The pre-processing gas pipe (1) extends from the gas generator and connects and supplies the mixed gas (pre-processing gas) generated in the device to the PSA device.

In addition, the pressurized gas pipe (3) is branched from the purified gas pipe (2), and uses part of the purified gas as pressurized gas to boost the pressure]
It is fed to the adsorption tower where the process is carried out.

In the figure, the A adsorption tower (9a) is in the adsorption process, in which one or more gases are selectively removed by an adsorbent from the pre-treatment gas introduced from the pre-treatment gas pipe (1), and the purified gas is The purified gas is continuously delivered through the purified gas line (2).

The B adsorption tower (9b) is in the desorption process, and in the adsorption process, which is the previous process, the gas immediately before the process is adsorbed by the adsorbent.
The second gas is discharged through the de-6 gas pipe (4).

In addition, at the beginning of this desorption process, B @W j? S(9
In b), the pressure is still high at 0 after the adsorption step, and the pressure in the 6 C absorption towers (9C) is low after the 12 step. Therefore, before the B adsorption tower (9b) performs the 151 output of desorption gas, the folding gas inlet truncated valve (7b) (7C
) and perform pressure equalization with the C adsorption tower (9C).

C @ Arrival tower (9C) is a pressurization process, and purified gas pipe (2
) A part of the purified gas is introduced into the C adsorption tower (9C) for pressurization through the pressurization gas pipe (3) branched from the pressurization gas pipe (3).

In the present invention, the pressure of the adsorption tower is increased using the pressure-boosting gas and flow control valve (17) provided in the pressure-boosting gas pipe (3) so as to prevent pressure fluctuations and flow rate fluctuations of the purified gas. A predetermined pressure (purified gas pressure) is set at a predetermined time (process switching time) and the flow rate is adjusted so that it becomes a continuous fixed amount.

The control means for controlling the flow rate of the pressurized gas as described above is constituted by a combi coater.

That is, as is well known, the combi coater is equipped with a CPU, a memory in which a program is stored, and a memory in which control data is stored. The pressure, adsorbent temperature, and back pressure gas flow rate of the adsorption tower performing the process are input via the A/D converter, and the control output signal is input to the back pressure gas flow tit control valve ( 17) is output.

Therefore, the PSA device has a means for reading the pressure of the purified gas in the first stage, and a purified gas pipe that converts the pressure of the purified gas into an electrical signal is installed downstream of the pressurized gas pipe (3) branch of the purified gas pipe (2). A pressure gauge (12) is installed in each adsorption tower (9a)<qb) (9c) as a means of reading the pressure of the adsorption tower,
The adsorption tower pressure it (
Connect 11a), (11b), and (11C), respectively.

Also, as a means of reading the adsorbent temperature, the pre-treatment gas pipe (
In 1), a pre-processing gas thermometer (18) is installed which converts the depletion of the pre-processing gas (which approximates the temperature of the adsorbent and regularly affects it) into an electrical signal.

Further, as a means for reading the flow rate of the pressurized gas, a pressurized gas flow meter (16) that converts the flow rate of the pressurized gas into an electrical signal is connected to the pressurized gas pipe (3).

When controlling the boosting gas flow rate according to the present invention, the boosting gas flow 11 set value is used to boost the pressure of the adsorption tower at a constant flow rate and to a predetermined pressure in a predetermined process time based on the input data from each of the above-mentioned reading means. The calculated value is compared with the actual boosting gas flow rate, and the boosting gas flow rate control valve (17) is opened so that the actual boosting gas flow rate matches the calculated boosting gas flow rate set value. Adjust the degree.

The control human input signal is constantly inputted throughout the entire period from the beginning to the end of the pressurization process, and thereby the pressurized gas flow rate set value is successively corrected.

Here, the principle of calculating the back pressure gas flow rate will be explained below.

VOI-: Boosting crab that boosts the pressure in the adsorption tower during the specified boosting period 1. m [Nm/II culm 1 V: Filling IJ of adsorbent packed in the adsorption tower [1T
11] Pl: Pressure of purified gas [g/cm2G] 3 P2: Pressure of adsorption tower performing pressure increasing step [Kg/cn
+2G] TSP: Specified boost period [5ec11” PV:
Progression time of gastric HT [scc] f: Adsorption amount of pressurized gas on adsorbent [Nm-oas/m-adsorbent/Kg10f] QSP: Pressurized gas meteor setting value [N/h] t: Adsorbent temperature [°C ] Then, the pressurizing gas ff1VOL necessary for pressurizing the adsorption tower is
is the relationship between the adsorption uX of the adsorbent and the suction pressure.VOL=(
Pl-P2>・V-1'・・・・・・・・・・・・・・・
・■, and from the relationship between the pressurized gas flow hl and the pressurization], VOL= QSP (TSP-TPV) /3600-
−・・−・−・−・−・■ From this, the unknown back pressure gas flow rate is as follows.

QPS-(Pi-1)2)・V-f/((TSPTPV
＞ /3600)・・・・・・・・・・・・・・・・・・
......■Here, f is a value determined by the temperature of the adsorbent packed in the adsorption tower, and can be approximated as follows.

f=a1・t+a2・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・■ However, al, a
2 is a constant determined by the type of adsorbent and the conditions of use, and 2 is a constant determined by the device and can be determined in advance.

Therefore, each of the above variables P1. P2. 'T°SP, T'P
V.

t is the calculation formula for ■■ above.
SP can be calculated.

In addition, the pressure P1 of the purified gas is measured using a gas pressure gauge manufactured by 'rN (
12), adsorbent temperature 1] is the pre-treatment gas temperature 1t (18
), the pressure P2 of the adsorption tower performing one culm of pressurization can be read directly from each adsorption tower pressure gauge 1 (11a).
(11b) Select and read the value read in (11c) from the sequence program for cutting.

Also, the defined back pressure period TSP, t? The progress time TPν of each pressure step is read from the step switching sequence program.

Such a calculation is performed by the calculating means (14) of the 21-input processor, and based on the calculated value and the read value of the pressurized gas flow rate (16) 5, the pressurized gas flow rate regulator (15) adjusts the boosted gas flow rate. The flow rate adjustment valve (17) is operated to control the flow rate of the pressurized gas.

At this time, the pressure of the adsorption tower performing the pressure increasing step is J3 when the pressure equalization T culm is completed, and as shown in FIG. This is caused by fluctuations in the adsorption capacity of the adsorbent, fluctuations in the final pressure value in the desorption process, etc., but as mentioned above, in order to calculate Pl and P2 by reading their opposite sides, A pressurized gas flow 1i is calculated, and upon completion of pressurization, the pressure is increased to a predetermined pressure by a constant amount.

J: Also, the adsorption capacity of the C1 adsorbent changes due to a change in the temperature of the pre-treatment gas, and the pressurized gas adsorption 1f of the adsorbent fluctuates. Therefore, the accuracy of calculation does not decrease due to changes in the adsorption capacity of the adsorbent.

In addition, when the viscosity is high and the pressure has been increased, the
In order to increase the pressure, the value of the pressurizing gas flow rate at the time when the R pressure progresses is always calculated 6 times continuously from the initial stage to the final stage of the culm. That is, the calculation and control of the pressurized gas flow rate during the pressurization step is shown in FIG.

■、■、■、■...Pl, P2. TSP.

Reading of the TPV, calculation of the value of the back pressure gas flow rate by the calculation means (14), and flow fft 11Ill fall by the pressurized gas flow section regulator (15) are repeatedly performed.

As a result, even if the adsorption capacity fluctuates over time due to various reasons, the relationship between the pressure in the adsorption tower that performs pressurization and the backpressure progress time can be established by connecting the initial pressure value of pressurization with the target pressure at the completion of pressurization in a straight line. The flow rate of the pressurized gas will be controlled to maintain a pressurized trajectory.

Next, an example of the control procedure will be explained according to the feature 1-1-chart 1- shown in FIG. Note that the number 1 (step) shown in FIG. 2 is shown.

First, in step O, the adsorbent filling amount V is read from the control data stored in the memory, and then ()'C''P
"SA is in operation or stopped" [The "in" flag is read from a separate PSA process switching sequence program, and when it is in operation, it shifts to O, and when it is stopped, the pressure increases] - Which adsorption tower is in the culm? is read from the process switching sequence program.

That is, in O, first the adsorption tower in the pressure increasing step is A adsorption tower (
9a), and if it is not the A adsorption tower (9a), then it is read whether it is the B adsorption tower (9b).

When the adsorption tower is a Δ adsorption tower (9a), the pressure of the A W absorption tower (9a) is set to 0, and when the adsorption tower is a B adsorption tower (9b), the pressure P2 of the B adsorption tower (9b) is set to O. The adsorption tower pressure gauges (11a) and (11b) read O.

If it is neither A nor B adsorption tower (9a) (9b), it means that it is C adsorption tower (9C), so it is read from "K" (11c) and shifts to O.

(12) Read like that.

8 Read the boosting process setting [, 1 interval TSP, and boosting process progress time TPv from the program.

Furthermore, in (), the pre-treatment gas temperature 1 is read from the pre-treatment gas thermometer, and in 4E), the temperature coefficients al and a2 of the adsorbent are read from the control data stored in the memory, and these pre-treatment gas temperature t and the adsorbent are Calculate the pressurized gas flow rate setting value QSP of the adsorbent based on the temperature coefficients a, , a2 of QSP←
(P+ P2)Vf/ ((-rsP--1-PV)
73600) L, ko17) m calculated value d1; The regulator (15) is the transmitted pressurized gas flow setting value QS.
P and the actual booster gas flow rate detected by the booster gas flow rate number (16) are constantly compared, and the inter-valve telegraph g is determined according to the difference between the two.
is output to the 27-pressure gas flow suspension control valve (17).

9 The pressurized gas flow rate control valve (17) receives the valve opening degree signal from the pressurized gas flow rate regulator (15), varies the valve opening degree, and adjusts the pressurized gas flow rate.

As a result of the above, the flow rate of the pressurized gas is automatically controlled so that the back pressure of the adsorption tower is brought to a predetermined pressure in a predetermined process switching cycle time, and the flow rate is continuously constant.

As a result of implementing this control device on a continuous M-made PSA, PSΔ
Fluctuations in the flow rate and pressure of purified gas could be suppressed to 2% or less without installing 4 nozzle tanks before and after.

(Effects) Since the present invention is configured as described above, it produces the effects described below.

1> Since the flow rate of the Pingtan gas is controlled so that the pressure in the adsorption tower is increased to a predetermined pressure in a predetermined process switching cycle time and the flow rate is continuously constant, continuous purification PSA is performed so that the flow rate of the purified gas 1.
Fluctuations in pressure can be minimized even without the need for a energy tank, reducing equipment installation area and construction costs.

2> Temporal fluctuations in the adsorption performance of the adsorbent due to changes in each process time of the adsorption tower, changes in the pressure of purified gas, temperature of the gas before treatment, regeneration of the adsorbent, and outside air temperature, etc. On the other hand, since C is also automatically calculated and controlled, the pressurized gas flow rate is fixed in any case, and the purified gas flow rate and pressure after treatment are also fixed and constant.

[Brief explanation of the drawing]

Fig. 1 is a flow sheet explaining the operating principle of the device for minimizing fluctuations in continuous purification in pressure swing adsorption of the present invention, Fig. 2 is a reflow chart showing the control procedure, and Fig. 3 is a flowchart explaining the operating principle of the device for minimizing fluctuations in continuous purification in pressure swing adsorption, and Fig. 3 is a reflow chart showing the control procedure. A graph showing the relationship between the variation in equalized pressure in the pressurization step and the pressure increase curve when the PSA method is carried out. Figure 4 shows the relationship between the pressure rise curve and the variation in equalized pressure in the pressure rise process when the PSA method is carried out. , is a graph showing the relationship between fluctuations in the adsorption characteristics of the adsorbent packed in the adsorption tower and the pressure increase curve. In the figure 1: Pre-treatment gas pipe 2: Purified gas pipe 1 3: Back pressure gas pipe 4: Desorption gas pipe! 1a-5c: Immediately before treatment gas on [] off tV valve 6a-6C
: Purified gas outlet switching valves 78 to 7C: Boosting gas inlet switching valves 8a to 8C: Desorption gas outlet switching valves 98 to 9C: Injection towers 11a to 11C: Adsorption tower pressure drop (adsorption tower pressure horn reading means) 12 : Purified gas pressure drop (purified gas pressure reading means) 13: Means for selecting and reading the pressure of the adsorption tower to be promoted 14: R pressure gas flow rate calculation means 15: Boosting gas flow rate regulator 16: Boosting gas flow meter (boosting gas flow meter) Gas flow rate reading means) 17: Boosting gas flow rate control valve 18: Pre-treatment gas hot stone 51 (adsorbent temperature reading means) 2 19:14 Seventh process progress time reading means Applicant: Seibu Gas Co., Ltd. Particularly 1 Applicant: Mitsubishi Oil Chemical 1-Engineering stock representative! ″+1 Masanai 3

Claims (1)

[Scope of Claim] A continuous purification device for a mixed gas that selectively removes one or more gas components from a supplied mixed gas by pressure swing adsorption using three or more adsorption towers in cycles. , in which a part of the purified gas is used for pressurization, an adsorption tower pressure reading means is provided in each adsorption tower and constantly reads the pressure of each adsorption tower and converts it into an electric signal, and an adsorption tower pressure reading means is provided in the purified gas pipeline and is used to increase the pressure of the purified gas. Purified gas pressure reading means for constantly reading gas pressure and converting it into an electrical signal; and adsorption state temperature reading means provided in the pre-processing gas pipeline for constantly reading the adsorption state temperature from the pre-processing gas temperature and converting it into an electrical signal. , identify the adsorption tower that executes the pressure increasing step based on the adsorption tower process switching sequence program in pressure swing adsorption, and select the detected value of the pressure reading means of the adsorption tower from among the detected values of the pressure reading means of each of the adsorption towers. Pressure boosting adsorption tower pressure reading means for selectively reading; Pressurization step progress time reading means for reading the pressurization process progress time based on the adsorption tower process switching sequence program; and the values read by each of the reading means and the adsorption process step switching sequence. A calculation means that constantly and continuously calculates the pressurized gas flow rate setting value from the pressurization process set time and pressurization process progress time set in the program, and a pressurization unit that branches from the purified gas pipe and connects to the adsorption tower that executes the pressurization process. a pressurized gas flow rate reading means provided in the gas pipe that constantly reads the actual flow rate of the pressurized gas and converts it into an electrical signal; a flow rate control valve provided in the pressurized gas pipe; and a pressurized gas calculated by the calculation means. A boost gas flow rate regulator that compares the flow rate set value and the actual boost gas flow rate read by the boost gas flow rate reading means, and controls the opening degree of the flow rate control valve so that the actual boost gas flow rate becomes the same as the boost gas flow rate set value. An apparatus for minimizing fluctuations in continuous purification in pressure swing adsorption, characterized by comprising: