JP5039861B1 - Product gas supply method and product gas supply system - Google Patents

Abstract

When a product gas obtained by the PSA method is compressed and supplied to a consumer side, the product gas is supplied at a stable gas pressure while suppressing power consumption even if the amount of gas consumed fluctuates. To provide a suitable method.
A method of separating a product gas enriched in a target gas by a PSA method from a mixed gas containing the target gas, compressing the product gas, and supplying the product gas at a first pressure. The step of separating the product gas from the mixed gas at 1; the step of compressing the product gas by the compressor 2; the step of measuring the flow rate of the product gas through the compressor 2 by the flow meter 5; Adjusting the flow rate of the product gas that has passed through the compressor 2 so as to become a predetermined flow rate setting value that is equal to or higher than the flow rate measurement value in the flow meter 31 upstream of the flow meter 5 according to the fluctuation; Adjusting the pressure of the product gas to and from the flow meter 31 to a second pressure greater than the first pressure.
[Selection] Figure 1

Description

  The present invention is suitable for separating a product gas enriched in a target gas from a mixed gas containing a target gas and unnecessary gas by a pressure fluctuation adsorption gas separation method and supplying the product gas to a consumer side at a predetermined pressure. It relates to a method and a system.

  Separating and recovering target oxygen and nitrogen from mixed gas containing oxygen and nitrogen such as air, recovering and purifying expensive argon from silicon crystal furnace, recovering and generating hydrogen from hydrogen-containing gas, biogas As a method for recovering methane for fuel from carbon dioxide or recovering carbon dioxide from carbon dioxide-containing gas with high purity, a pressure fluctuation adsorption gas separation method (PSA method) is known. For example, oxygen-enriched oxygen gas (product gas) obtained by the PSA method is used in fields that consume large amounts of oxygen, such as chemical reactions, electric furnace steelmaking, garbage incineration, papermaking, and oxygen aeration in water treatment facilities. ing. In the separation of oxygen gas by the PSA method, for example, a cycle including an adsorption step and a desorption step is repeatedly performed in each adsorption tower using a PSA gas separation apparatus having at least one adsorption tower filled with an adsorbent. .

  For example, when oxygen gas obtained by the PSA method is used for chemical production, the pressure of the oxygen gas affects the chemical reaction. Therefore, it is required to supply the oxygen gas while maintaining a stable consumption gas pressure. . In addition, since the pressure of oxygen gas used in the manufacture of chemical products usually requires a high pressure of several hundred kPa (gauge pressure) or higher, oxygen gas separated by the PSA method is blown or compressed (compressed). After being compressed by means), it is supplied to the consumer side. On the other hand, the oxygen gas consumption (consumption gas amount) in the chemical reaction is not always constant and may vary.

  If the oxygen gas consumption (gas consumption) fluctuates, the gas flow differential pressure will change even if only the oxygen gas supply (gas delivered from the compressor) is adjusted. It cannot be kept constant. That is, when the amount of consumed gas increases, the flow differential pressure in the pipe increases, so that the consumed gas pressure drops while the pressure of oxygen gas (supply gas pressure) passing through the compressor (compression means) remains constant. On the other hand, when the amount of consumed gas decreases, the flow differential pressure decreases, so that the consumed gas pressure increases if the pressure of oxygen gas (supply gas pressure) that has passed through the compressor (compression means) remains constant. For this reason, in order to maintain the consumption gas pressure constant regardless of fluctuations in the consumption gas amount, the oxygen gas supply amount (supply gas amount) must be adjusted, and the supply gas pressure must be adjusted to match the consumption gas amount. is required.

  In Patent Document 1, the generation amount of oxygen gas is adjusted by changing the switching timing of the cycle executed in the PSA gas separation device in accordance with the fluctuation of the consumption amount (consumption gas amount) of oxygen gas input and set in advance. A method for adjusting the supply amount and supply gas pressure of oxygen gas by controlling the rotational speed of a blower for compressing the separated oxygen gas is also shown. However, in this method, it is necessary to input the gas consumption amount in advance. Moreover, since it is necessary to adjust the rotation speed of the blower according to the set value of the consumed gas amount, when the consumed gas amount fluctuates arbitrarily, it was not possible to cope with the adjustment of the consumed gas pressure. .

  In order to solve such a problem, a countermeasure may be taken such that a buffer tank is provided on the downstream side of the compressor or the like, and a pressure adjusting valve is further installed at the outlet of the buffer tank. When a buffer tank is installed, oxygen gas (product gas) is stored in the buffer tank to absorb fluctuations in the amount of gas consumed, and even if the amount of gas consumed increases or decreases, the gas pressure is adjusted so that it is always constant. Was. However, in this case, if the amount of gas consumed decreases, the supply gas pressure of the product gas that has passed through the blower or compressor will be raised to a pressure that is much higher than the consumption gas pressure, resulting in excessive consumption power of the compressor or the like. It was.

JP 2000-356323 A

  The present invention has been conceived under such circumstances, and when the product gas obtained by the PSA method is compressed and supplied to the consumption side, the consumption power is changed even if the consumption gas amount fluctuates. It is an object of the present invention to provide a method and system suitable for supplying product gas at a stable consumption gas pressure while suppressing the above.

  A product gas supply method provided by the first aspect of the present invention separates a product gas enriched in a target gas by a pressure fluctuation adsorption gas separation method from a mixed gas containing the target gas and an unnecessary gas, A method of compressing and supplying a product gas at a first pressure, the step of separating the product gas from the mixed gas by a pressure fluctuation adsorption gas separation method, and the step of compressing the product gas by a compression means Measuring the flow rate of the product gas that has passed through the compression means at the first measurement point, and changing the first measurement point according to a variation in the flow rate measurement value of the product gas at the first measurement point. Adjusting the flow rate of the product gas that has passed through the compression means so that a predetermined flow rate set value that is greater than or equal to the flow rate measurement value at a second measurement point that is upstream of the first measurement point; Adjusting the pressure of the product gas at a third measurement point between the measurement point and the second measurement point to a second pressure that is greater than the first pressure. Features.

  Preferably, the pressure adjustment to the second pressure is performed by releasing a part of the product gas to the outside.

  Preferably, the flow rate of the product gas at the second measurement point is adjusted by circulating a part of the product gas that has passed through the compression means upstream of the second measurement point to the suction side of the compression means. To do.

  Preferably, in the step of setting a plurality of flow rate setting values each assigned corresponding to the flow rate measurement value within a predetermined range and adjusting the flow rate, the flow rate measurement value decreases below the predetermined range. When the flow rate of the product gas at the second measurement point is decreased so that the current flow rate set value becomes the next lower flow rate set value, the flow rate measured value increases beyond the predetermined range. At this time, the flow rate of the product gas at the second measurement point is increased so that the current flow rate setting value becomes the next highest flow rate setting value.

  Preferably, the second pressure is in a range of 1 to 10% higher than the first pressure in terms of gauge pressure.

  Preferably, the flow rate measurement value is an amount of gas that has passed through the first measurement point per unit time.

  A product gas supply system provided by the second aspect of the present invention separates a product gas enriched in a target gas by a pressure fluctuation adsorption method from a mixed gas containing the target gas and an unnecessary gas, and supplies the product gas. A system for compressing and supplying the product gas by a pressure fluctuation adsorption gas separation method using an adsorption tower filled with an adsorbent that selectively adsorbs the unnecessary gas from the mixed gas. Pressure separation adsorption type gas separation device for separation, compression means for compressing the product gas, flow rate measurement means for measuring the flow rate of the product gas passing through the compression means, and through the compression means Based on the flow rate adjustment means for adjusting the flow rate of the product gas before the product gas is supplied to the flow rate measurement means, and the flow rate measurement value measured by the flow rate measurement means, Control means for adjusting the flow rate by the flow rate adjusting means, and pressure adjusting means for adjusting the pressure of the product gas before the product gas that has passed through the flow rate adjusting means is supplied to the flow rate measuring means. It is characterized by providing.

  Preferably, the flow rate adjusting means derives a gas flow meter for measuring the flow rate of the product gas that has passed through the compression means, and the product gas that has passed through the compression means from the upstream side of the gas flow meter, A bypass for circulating to the suction side of the compression means, and a flow rate adjusting valve for adjusting the flow rate of the product gas flowing through the bypass.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

1 is a schematic configuration diagram of a product gas supply system that can be used to execute a product gas supply method according to the present invention. It is a flowchart which shows an example of the process sequence for adjusting a consumption gas pressure according to the consumption gas quantity in the product gas supply method which concerns on this invention. It is a schematic block diagram of the product gas supply system which can be used in order to perform the product gas supply method which concerns on a comparative example. The change of the internal pressure of the buffer tank in the product gas supply method which concerns on a comparative example is represented.

  A product gas supply method according to a preferred embodiment of the present invention will be specifically described with reference to the drawings.

  FIG. 1 shows a schematic configuration of a product gas supply system X that can be used to execute the product gas supply method according to the present embodiment. The product gas supply system X includes a PSA gas separation device 1, a compressor 2, a flow rate adjustment mechanism 3, a pressure adjustment mechanism 4, a consumption gas flow meter 5, a pipe 6 connecting them, a control device 7, The product gas enriched in the target gas is separated from the mixed gas containing the target gas and the unnecessary gas, and the product gas can be compressed and supplied to the consumer side. In this embodiment, the case where oxygen is separated from air (mixed gas) containing oxygen as a target gas and nitrogen as an unnecessary gas in the PSA gas separation apparatus 1 will be described.

  The PSA gas separation apparatus 1 includes at least one adsorption tower (not shown) filled with an adsorbent mainly for preferentially adsorbing nitrogen (unnecessary gas), and pressure fluctuation adsorption performed using the adsorption tower. Oxygen-enriched gas (product gas) can be taken out from air, which is an oxygen / nitrogen-containing gas, by the gas separation method. Examples of the adsorbent packed in the adsorption tower include Ca-A type zeolite, Ca-X type zeolite, and Li-X type zeolite, which can be used alone or in combination. Good.

  In the pressure fluctuation adsorption gas separation method executed by the PSA gas separation apparatus 1, a cycle including an adsorption step, a desorption step, and a regeneration step is repeated for a single adsorption tower. In the adsorption step, air is introduced into an adsorption tower having a predetermined high pressure in the tower, nitrogen and other components (carbon dioxide, moisture, etc.) in the air are adsorbed by the adsorbent, and oxygen is adsorbed from the adsorption tower. This is a process for deriving an enriched gas (product gas). The desorption step is a step for depressurizing the inside of the adsorption tower to desorb nitrogen from the adsorbent and discharging the nitrogen out of the tower. The regeneration step is a step for recovering the adsorption performance of the adsorbent for nitrogen, for example, by passing a cleaning gas through the tower in order to provide the adsorption column in the second adsorption step. As such a PSA gas separation apparatus 1, a known PSA oxygen separation apparatus can be used.

  The compressor 2 is for compressing the oxygen-enriched gas (product gas) separated by the PSA gas separation device 1 and sending it to the consumer side.

  The flow rate adjusting mechanism 3 is for adjusting the flow rate of the product gas that has passed through the compressor 2, and includes a supply gas flow meter 31, a bypass pipe 32, and a bypass valve 33. The supply gas flow meter 31 is for measuring the instantaneous flow rate of the product gas passing through the pipe 6 through the compressor 2 at the second measurement point. The bypass pipe 32 is connected to the pipe 6 and circulates part of the product gas that has passed through the compressor 2 to the suction side of the compressor 2 again. One end of the bypass pipe 32 is connected to the discharge side (downstream side) of the compressor 2 and the upstream side of the supply gas flow meter 31, and the other end of the bypass pipe 32 is connected to the suction side (upstream side) of the compressor 2. It is connected to the. The bypass valve 33 is provided in the bypass pipe 32. The bypass valve 33 is for adjusting the flow rate of the product gas flowing through the bypass pipe 32, and is a valve capable of adjusting the opening degree. The degree of opening of the bypass valve 33 is adjusted by a signal from the control device 7 described later.

  The consumption gas flow meter 5 is for measuring the flow rate (consumption gas amount) of the product gas sent to the consumption side via the compressor 2 at the first measurement point. The consumption gas flow meter 5 is provided on the downstream side of the supply gas flow meter 31 described above, and measures the amount of gas that has passed per unit time (integrated average gas amount or moving average gas amount). Here, the integrated average gas amount is, for example, the integrated gas amount that has passed during a certain measurement time, such as 1 to 30 cycles, preferably 5 to 10 cycles, for the above-described cycle executed by the PSA gas separation device 1. It is. The moving average gas amount indicates an integrated gas amount measured while shifting the measurement start time and the measurement end time as time passes while maintaining the measurement time constant.

  The pressure adjusting mechanism 4 is for adjusting the pressure of the product gas (second pressure) at a third measurement point that is an intermediate part between the supply gas flow meter 31 and the consumption gas flow meter 5. The pressure adjustment mechanism 4 includes a discharge pipe 41 connected to the pipe 6, a purge valve 42, and a pressure controller 43. The discharge pipe 41 is for releasing a part of the product gas that has passed through the supply gas flow meter 31 to the outside, and one end is connected between the supply gas flow meter 31 and the consumption gas flow meter 5. At the same time, the other end is open to the outside. The purge valve 42 is provided in the discharge pipe 41 and is a valve whose opening degree can be adjusted. The pressure controller 43 constantly measures the pressure of the product gas flowing through the pipe 6 and adjusts the opening of the purge valve 42 according to the measured pressure, thereby adjusting the pressure of the product gas to a desired value. It is for controlling. The pressure adjustment mechanism 4 is configured such that the opening degree of the purge valve 42 is adjusted as desired according to the pressure measured by the pressure controller 43.

  The control device 7 is for adjusting the flow rate of the product gas by the flow rate adjusting mechanism 3 based on the consumed gas amount (flow rate measurement value) of the product gas measured by the consumed gas flow meter 5. The control device 7 opens the bypass valve 33 so that the flow rate measured by the supply gas flow meter 31 becomes a predetermined flow rate set value that is equal to or higher than the flow rate measured value in accordance with the fluctuation of the consumed gas amount (flow rate measured value). Adjust the degree. In the control device 7, the opening degree of the bypass valve 33 is adjusted by executing a predetermined program.

  In the present embodiment, the following control is performed by the control device 7. The control device 7 is input and set with a plurality of flow rate setting values assigned in correspondence with the consumption gas amount (flow rate measurement value) within a predetermined range. When the consumption gas amount (flow rate measurement value) measured by the consumption gas flow meter 5 decreases beyond a predetermined range, the control device 7 causes the current flow rate setting value to become the next smaller flow rate setting value. A signal is sent to the supply gas flow meter 31 to adjust the opening in the direction in which the bypass valve 33 is opened, and the flow rate of the product gas flowing through the bypass pipe 32 is increased. Thereby, the flow rate of the product gas passing through the supply gas flow meter 31 is reduced. On the other hand, when the gas consumption (flow rate measurement value) increases beyond the predetermined range, the control device 7 sends a signal to the supply gas flow meter 31 so that the current flow rate set value becomes the next highest flow rate set value. To adjust the opening degree in the direction of closing the bypass valve 33, the flow rate of the product gas flowing through the bypass pipe 32 is decreased. As a result, the flow rate of the product gas passing through the supply gas flow meter 31 increases.

  The product gas that has passed through the consumption gas flow meter 5 is constantly consumed for a predetermined application.

  During operation of the product gas supply system X having the above configuration, air (mixed gas) is introduced into the PSA gas separation device 1. In the PSA gas separation apparatus 1, a cycle including an adsorption process, a desorption process, and a regeneration process is repeated for each adsorption tower, and a product gas enriched in oxygen is continuously taken out.

The product gas from the PSA gas separation device 1 is compressed by the compressor 2 and supplied to the consumption side at a predetermined consumption gas pressure. The consumption gas pressure is 0.2 MPa (gauge pressure), for example, although it varies depending on the usage on the consumption side. In addition, the consumption amount of the product gas (consumption gas amount) in the consuming equipment or the like may vary. The supply amount (supply gas amount) of the product gas sent to the consumption side via the compressor 2 and the supply gas flow meter 31 is set so as to correspond to the maximum consumption amount of the product gas on the consumption side. For example, when the maximum consumption of the product gas on the consumption side is 200 Nm ³ / h, the acquisition amount of the product gas taken out from the PSA gas separation device 1 is 200 Nm ³ / h, and the product gas flowing through the compressor 2 The flow rate is 200 Nm ³ / h.

  In the pressure adjustment mechanism 4, the pressure of the product gas in the pressure controller 43 (the supply gas pressure of the product gas in the intermediate portion between the supply gas flow meter 31 and the consumption gas flow meter 5. However, it is adjusted so that it may become a range 1-10% higher than consumption gas pressure (1st pressure) as a gauge pressure, Preferably it is adjusted so that it may become about 5% higher than consumption gas pressure. When the consumption gas pressure is 0.2 MPa (gauge pressure), the intermediate pressure is adjusted to 0.21 MPa (gauge pressure). Thus, adjusting the intermediate part pressure to be slightly higher than the consumption gas pressure takes into consideration that an appropriate gas flow differential pressure is generated between the upstream side and the downstream side of the consumption gas flow meter 5. It is what.

  For example, if the amount of gas consumed on the consumption side decreases and the amount of gas supplied becomes greater than the amount of gas consumed, the intermediate pressure increases, so the opening of the purge valve 42 is adjusted in the direction to open the purge valve 42. . As a result, a part of the excessive product gas that has increased the intermediate pressure is discharged to the outside through the discharge pipe 41. As described above, the intermediate pressure is adjusted by releasing a part of the product gas to the outside.

FIG. 2 is a flowchart showing an example of a processing procedure for adjusting the consumption gas pressure in accordance with the consumption gas amount when the product gas supply system X is in operation. FIG. 2 shows the case where the maximum consumption amount of the product gas on the consumption side is 200 Nm ³ / h.

  Prior to the operation of the product gas supply system X, the measurement time of the consumption gas flow meter 5 is input to the control device 7. This measurement time is preferably such that fluctuations in the amount of product gas generated in the PSA gas separation device 1 are averaged. As such measurement time, about the said cycle performed with the PSA gas separation apparatus 1, they are 1 cycle or more and 30 cycles or less, Preferably the time of 5 to 10 cycles is mentioned. The consumed gas amount (flow rate measurement value) measured by the consumed gas flow meter 5 is a gas amount per unit time, but it is preferable to measure the above-mentioned moving average gas amount by the consumed gas flow meter 5.

Further, a plurality of flow rate setting values assigned according to the consumption gas amount within a predetermined range are input to the control device 7. Here, the flow rate set value is set as a load set gas amount (load factor) with respect to the maximum consumption amount 200 Nm ³ / h of the product gas. For example, 100% load ^{(200Nm 3 / h), 90} % load ^{(180Nm 3 / h), 80} % load ^{(160Nm 3 / h), 70} % load ^{(140Nm 3 / h), 60} % load (120 Nm ³ / h ), Etc., in 10% increments. When setting the load factor as the flow rate setting value in increments of 10%, for example, “180 Nm ³ / h <consumed gas amount ≦ 200 Nm” at 100% load as the “predetermined range of consumed gas amount” corresponding to each load factor. ³ / h ", the 90% load" 160 Nm ³ / h <gas consumption ≦ 180 Nm ³ / h ", the 80% load" 140 Nm ³ / h <gas consumption ≦ 160 Nm ³ / h ", the 70% load" 120 nm ³ / h <gas consumption ≦ 140 Nm ³ / h ", is 60% load" 100 Nm ³ / h <gas consumption ≦ 120 nm ³ / h ", are.

  After the start of the operation of the product gas supply system X, the measurement of the consumption gas amount by the consumption gas flow meter 5 and the adjustment of the intermediate pressure are always performed (S10). Then, the current load factor (flow rate setting value) is determined. When the current load factor is 80%, NO is determined in the determination whether the load is 100% (S11), NO is determined in the determination whether the load is 90% (S12), and the load is 80%. Whether or not (S13) is YES. Next, it progresses to determination of intermediate part pressure.

Here, when the actual gas consumption (flow rate measured by the gas consumption flow meter 5) is 160 Nm ³ / h, the supply gas flow meter 31 receives an 80% load setting signal from the control device 7 and bypass valve. The opening of 33 is adjusted, and the amount of supply gas passing through the supply gas flow meter 31 is already 160 Nm ³ / h. For this reason, the intermediate pressure does not increase, and the purge valve 42 is closed. As a result, the amount of gas discharged from the discharge pipe 41 becomes 0 Nm ³ / h, and the amount of gas supplied and the amount of gas consumed are well balanced.

At this time, the intermediate pressure is adjusted to 0.21 MPa (gauge pressure), which is slightly higher than the consumption gas pressure of 0.2 MPa (gauge pressure) by the pressure adjusting mechanism 4. In the determination (S24) of whether or not “21 MPaG”, the process proceeds to the next determination (S25) of whether or not “consumed gas amount> 140 Nm ³ / h”. Here, since the gas consumption ^{(160Nm 3 / h)> 140Nm} 3 / h, S25 is determined to be YES, 80% load is continued (S37). Next, the process returns to the determination of the current load factor.

Thereafter, when the amount of gas consumed (measured flow rate) increases to 170 Nm ³ / h, the current load factor is determined as YES in the determination of whether or not the load is 80% (S13). At this time, the actual amount of gas consumed (170 Nm ³ / h) is larger than the amount of gas supplied at 80% load (160 Nm ³ / h). (140 Nm ³ / h <consumed gas amount ≦ 160 Nm ³ / h) ”. For this reason, the intermediate portion pressure drops and the determination of whether or not “intermediate portion pressure <0.21 MPaG” is satisfied (S24), YES, and the load factor is changed to 90% load (S36). Here, the supply gas flow meter 31 receives a 90% load setting signal from the control device 7 and adjusts the opening degree in a direction to close the bypass valve 33, thereby reducing the amount of product gas circulating through the bypass pipe 32. . By such processing, the amount of the supply gas passing through the supply gas flow meter 31 is increased to 180 Nm ³ / h.

At this time, the amount of feed gas (180Nm ³ / h) is consumed gas amount (170Nm ³ / h) greater than, it means that the product gas is excessively supplied 10 Nm ³ / h, the intermediate portion pressure increases. Therefore, the opening degree of the purge valve 42 is adjusted by the pressure controller 43 in the direction in which the purge valve 42 is opened, and the excessively supplied product gas is discharged to the outside through the discharge pipe 41. Thus, the intermediate pressure is adjusted to 0.21 MPa (gauge pressure), which is slightly higher than 0.2 MPa (gauge pressure), which is the consumption gas pressure, by the pressure adjusting mechanism 4. Thereafter, returning to the determination of the current load factor, if the consumed gas amount remains at 170 Nm ³ / h, the determination of whether or not the load is 90% is YES (S12), and “intermediate pressure <0.21 MPaG NO in the determination (S22) or not, and YES in the next determination (S23) whether or not "consumed gas amount> 160 Nm ³ / h", and 90% load is continued (S34). ). Thereafter, returning to the determination of the current load factor, the same processing operation is repeated.

Thereafter, when the amount of gas consumed (measured flow rate) decreases to 150 Nm ³ / h, the current load factor is determined as YES in the determination of whether or not the load is 90% (S12). At this time, the actual amount of gas consumed (150 Nm ³ / h) is smaller than the amount of gas supplied at 90% load (180 Nm ³ / h). It decreases below (160 Nm ³ / h <consumed gas amount ≦ 180 Nm ³ / h) ”. For this reason, the intermediate part pressure rises to 0.21 MPaG or more. Therefore, it is NO in the next determination of whether or not “intermediate pressure <0.21 MPaG” (S22), and the next determination of whether or not “consumption gas amount> 160 Nm ³ / h” (S23). Move on. Here, since the consumption gas amount (150 Nm ³ / h) <160 Nm ³ / h, S23 is determined to be NO, and the load factor is changed to 80% load (S35). Here, the supply gas flow meter 31 receives an 80% load setting signal from the control device 7 and adjusts the opening in the direction in which the bypass valve 33 is opened, thereby increasing the amount of product gas circulating through the bypass pipe 32. . By such processing, the amount of the supply gas passing through the supply gas flow meter 31 is reduced to 160 Nm ³ / h.

At this time, the supply gas amount (160 Nm ³ / h) is larger than the consumption gas amount (150 Nm ³ / h), and the product gas is supplied in excess of 10 Nm ³ / h, so the intermediate pressure increases. Therefore, the purge valve 42 is opened by the pressure controller 43 in the same manner as in the case where the amount of consumed gas is 170 Nm ³ / h, and the excessively supplied product gas continues to be discharged to the outside via the discharge pipe 41. Thus, the intermediate pressure is maintained at 0.21 MPa (gauge pressure), which is slightly higher than 0.2 MPa (gauge pressure), which is the consumption gas pressure, by the pressure adjusting mechanism 4. Thereafter, returning to the determination of the current load factor, if the consumed gas amount remains at 150 Nm ³ / h, YES in the determination of 80% load (S 13) and “intermediate pressure <0.21 MPaG”. (NO in the determination (S24)), YES is determined in the next determination (S25) as to whether or not “consumed gas amount> 140 Nm ³ / h”, and the 80% load is continued (S37). Thereafter, returning to the determination of the current load factor, the same processing operation is repeated.

  As described above, according to the product gas supply method performed using the product gas supply system X, even if the consumption gas amount fluctuates, the supply gas amount and the intermediate part pressure are appropriately adjusted, so that the stable consumption gas pressure can be obtained. Product gas can continue to be supplied to the consumer.

  In the present embodiment, the intermediate pressure (second pressure) is adjusted to be slightly higher than the consumption gas pressure (first pressure). Such a method is suitable for suppressing power consumption by the compressor 2.

  In the method described above with reference to the flowchart of FIG. 2, the case where the load factor as the flow rate setting value is set in increments of 10% has been described as an example. However, if the load factor is set more finely (for example, in increments of 5%). Thus, the amount of gas discharged excessively can be reduced, and the supply gas amount can be smoothly adjusted in accordance with the fluctuation of the consumption gas amount.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention.

  The product gas supply method according to the present invention is not limited to the case where oxygen is used as the target gas as in the above-described embodiment, but can also be applied to cases where other component gases are used as the target gas.

  Next, the usefulness of the present invention will be described with reference to examples and comparative examples.

〔Example〕
In the present embodiment, the product gas supply system X shown in FIG. 1 is used to separate the oxygen-enriched gas, which is the product gas, from the air as the mixed gas, and supply it to the consumer side under the conditions shown below. did.

In this example, a two-column PSA oxygen separation device including two adsorption towers was used as the PSA gas separation device 1. Each adsorption tower of this apparatus was filled with zeolite molecular sieve as an adsorbent. This device was used to separate product gas from air. The acquisition amount of the product gas taken out from the PSA gas separation device 1 was 200 Nm ³ / h.

As the compressor 2, a compressor having a capacity of 200 Nm ³ / h was used.

During operation of the product gas supply system X in this embodiment, while the intermediate portion pressure (second pressure) is adjusted to be 0.21 MPa, 150 Nm ³ / h of gas consumption of the product gas from 200 Nm ³ / h For 10 minutes, and then the gas consumption is increased from 150 Nm ³ / h to 170 Nm ³ / h for 10 minutes, and then the gas consumption is restored from 170 Nm ³ / h to the original 200 Nm ³ / h for 10 minutes. Driving continued for a minute. During this 30 minutes, the product gas was continuously consumed while measuring the power consumption of the compressor 2.

  The adjustment of the supply gas amount and the adjustment of the intermediate pressure accompanying the change in the consumption gas amount were performed in accordance with the processing procedure of the flowchart shown in FIG.

  As a result, even if the amount of gas consumed fluctuates, the gas pressure is stable at 0.2 MPa (gauge pressure), and the accumulated power consumption for 30 minutes in the compressor 2 is 4.3 kW, which is an average consumption per hour. The power was 8.6 kWh.

[Comparative Example]
In this comparative example, using the product gas supply system Y shown in FIG. 3, the oxygen-enriched gas as the product gas is separated from the air as the mixed gas under the conditions shown below, compressed and supplied to the consumer side did.

The configuration and gas separation mode of the PSA gas separation apparatus 101 used in this comparative example were the same as those in the above example, and the amount of product gas taken out from the PSA gas separation apparatus 101 was 200 Nm ³ / h. A compressor 102 is provided on the downstream side of the PSA gas separation apparatus 101. The compressor 102 is the same as the compressor 2 of the above embodiment. Connected to the pipe 103 is a bypass pipe 104 for recirculating the product gas that has passed through the compressor 102 into the compressor 102 and circulating it. The bypass pipe 104 is provided with a switching valve 105 that can be switched between an open state and a closed state. A gas flow meter 106 for measuring the amount of product gas supplied is provided downstream of the compressor 101, and a buffer tank 107 is provided downstream of the gas flow meter 106. The buffer tank 107 has an internal capacity of 22 m ³ and can absorb fluctuations in the amount of gas consumed at an internal pressure with a maximum pressure of 0.9 MPa (gauge pressure) and a minimum pressure of 0.21 MPa (gauge pressure). I was able to do it. A pressure regulating valve 108 and a consumption gas flow meter 109 are provided at the outlet of the buffer tank 107, and the consumption gas pressure is reduced to 0.2 MPa (gauge pressure) so that the consumption gas can be sent stably. I was able to do it.

During operation of the product gas supply system Y in this comparative example, the switching valve 105 is first closed, the consumption gas amount is reduced from 200 Nm ³ / h to 150 Nm ³ / h for 10 minutes, and then the consumption gas amount is 150 Nm. ^The operation was continued for 10 minutes by increasing from ³ / h to 170 Nm ³ / h, and then returning the consumption gas from 170 Nm ³ / h to the original 200 Nm ³ / h. During the 30 minutes, the product gas was continuously consumed while measuring the power consumption of the compressor 102.

The change in the internal pressure of the buffer tank 107 in this comparative example is shown in FIG. As shown in the figure, the internal pressure of the buffer tank 107 continues to rise when the amount of gas consumed is 150 Nm ³ / h and 170 Nm ³ / h, and a maximum pressure of 0.9 MPa (20 MPa 20 minutes after the start of measurement) Reached the gauge pressure). After that, the switching valve 105 was opened for 4 minutes so that the pressures on the discharge side and the suction side of the compressor 102 were equalized to be in an unloaded state. The switching valve 105 was closed when the internal pressure of the buffer tank 107 dropped to 0.21 MPa. For the remaining 6 minutes, the amount of gas consumed and the amount of gas supplied were balanced, and the internal pressure of the buffer tank 107 was constant.

  As a result, even if the amount of gas consumed fluctuates, the gas pressure is stable at 0.2 MPa (gauge pressure), and the accumulated power consumption for 30 minutes in the compressor 102 is 6.4 kW, and the average consumption per hour The power was 12.8 kWh.

  As can be understood by comparing the above-described example and the comparative example, in the case of the example, even when the amount of consumed gas fluctuates, the product gas is supplied at a stable consumed gas pressure while suppressing the consumed power. It was possible.

X Product Gas Supply System 1 PSA Gas Separator 2 Compressor 3 Flow Control Mechanism 31 Supply Gas Flow Meter 32 Bypass Pipe 33 Bypass Valve 4 Pressure Control Mechanism 41 Release Pipe 42 Purge Valve 43 Pressure Controller 5 Consumption Gas Flow Meter 6 Pipe 7 Control device

Claims (7)

This is a method in which a product gas enriched in a target gas is separated from a mixed gas containing a target gas and an unnecessary gas by a pressure fluctuation adsorption gas separation method, and the product gas is compressed and supplied at a first pressure. And
Separating the product gas from the mixed gas by a pressure fluctuation adsorption gas separation method;
Compressing the product gas by a compression means;
Measuring the flow rate of the product gas through the compression means at a first measurement point;
A predetermined flow rate setting value that is greater than or equal to the flow rate measurement value at a second measurement point upstream of the first measurement point in response to a change in the flow rate measurement value of the product gas at the first measurement point. Adjusting the flow rate of the product gas through the compression means at the second measurement point so that
Adjusting the pressure of the product gas at a third measurement point between the first measurement point and the second measurement point to a second pressure that is greater than the first pressure; only including,
The pressure adjustment to the second pressure is performed via a discharge pipe branching from a pipe connecting the first measurement point and the second measurement point, and a purge valve with an adjustable opening degree provided in the discharge pipe. A method for supplying a product gas, wherein a part of the product gas is discharged to the outside .   The flow rate of the product gas at the second measurement point is adjusted by circulating a part of the product gas that has passed through the compression means upstream of the second measurement point to the suction side of the compression means. The product gas supply method according to claim 1, wherein the product gas supply method is performed. A plurality of flow rate setting values each assigned corresponding to the flow rate measurement value within a predetermined range are set,
In the step of adjusting the flow rate, when the flow rate measurement value decreases below the predetermined range, the flow rate set value at the second measurement point is set to be the next lower flow rate set value from the current flow rate set value. When the flow rate of the product gas is decreased and the flow rate measurement value is increased beyond the predetermined range, the flow rate set value is set to the next highest flow rate set value from the current flow rate set value. The product gas supply method according to claim 1 or 2 , wherein the flow rate of the product gas is increased. Said second pressure is in the gauge pressure in 1-10% range higher than the first pressure, the product gas supply method according to any one of claims 1 to 3. The product gas supply method according to any one of claims 1 to 4 , wherein the flow rate measurement value is a gas amount that has passed through the first measurement point per unit time. A system for separating a product gas enriched in a target gas from a mixed gas containing a target gas and an unnecessary gas by a pressure fluctuation adsorption method, and compressing and supplying the product gas,
A pressure fluctuation adsorption gas separation device for separating the product gas by a pressure fluctuation adsorption gas separation method performed using an adsorption tower filled with an adsorbent that selectively adsorbs the unnecessary gas from the mixed gas; ,
Compression means for compressing the product gas;
A flow rate measuring means for measuring the flow rate of the product gas that has passed through the compression means at a first measurement point ;
A flow rate adjusting means for adjusting the flow rate of the product gas before the product gas having passed through the compression means is supplied to the flow rate measuring means;
Based on the flow rate measurement value at the first measurement point measured by the flow rate measurement means , a predetermined flow rate that is equal to or higher than the flow rate measurement value at a second measurement point upstream of the first measurement point. and control means for performing a flow control in the I Ri said second measurement point in the flow rate control means so that the setting value,
Pressure adjusting means for adjusting the pressure of the product gas before the product gas passed through the flow rate adjusting means is supplied to the flow rate measuring means ,
The pressure adjusting means is configured to supply the product gas via a discharge pipe branching from a pipe connecting the first measurement point and the second measurement point, and a purge valve provided in the discharge pipe. A product gas supply system for adjusting a pressure of the product gas before being supplied to the flow rate measuring means by discharging a part thereof to the outside . The flow rate adjusting means is a gas flow meter for measuring the flow rate of the product gas that has passed through the compression means, and the product gas that has passed through the compression means is led out from the upstream side of the gas flow meter. The product gas supply system according to claim 6 , further comprising: a bypass for circulating to the suction side of the gas and a flow rate adjusting valve for adjusting a flow rate of the product gas flowing through the bypass.

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