JPH11179135A - Nitrogen gas manufacturing apparatus and its operating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce power of an apparatus in an ordinary operation and a low operation ratio by a method wherein when nitrogen gas of a required pressure is obtained with a pressure swing type gas separator, a nitrogen gas compressor is provided in a downstream side of the gas separator. SOLUTION: Air is pressurized to a required pressure with an air compressor 1, and supplied to a pressure swing system (PSA system) gas separator 3 via a piping 2. Nitrogen gas to be manufactured with the gas separator 3 passes through a piping 4 to be pressurized up to a necessary pressure with a nitrogen gas compressor 5, and is supplied to a nitrogen gas tank 7 via a piping 6. Instead of controlling a capacity of the air compressor 1 to a minimum limit of a pressure wherein the PSA system gas separator 3 can efficiently separate gas, a capacity of the nitrogen gas compressor 5 is raised to achieve a specific capacity, and the nitrogen gas compressor 5 is stopped in standby operation. An operation cost can be controlled by reducing power of the compressor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing nitrogen gas from air by a pressure swing type (PSA) gas separation method using an adsorbent.

[0002]

2. Description of the Related Art An example of a conventionally used PSA type gas separation apparatus will be described with reference to FIG. This is a case where nitrogen is produced from the atmosphere. Air is pressurized by an air compressor 1 and supplied to a PSA-type gas separation device 3 through a pipe 2.

[0003] The nitrogen gas produced by the PSA type gas separation device 3 is supplied to a nitrogen gas tank 7 via a pipe 4. In the PSA-type gas separator 3, nitrogen gas is produced at a pressure of about 2 kg / cm ² lower than the pressure of the supplied air, so that in the air compressor 1, the pressure required in the nitrogen gas tank 7 is 2 kg / cm ^2. The air is pressurized about G higher.

[0004]

In a conventional nitrogen gas producing apparatus using a PSA-type gas separating apparatus, a large part of the operating cost is the power of the compressor. In particular, the air compressor has a large flow rate, which causes an increase in operating costs.

[0005] Further, the PSA-type gas separation apparatus requires continuous operation to maintain its performance, so that the production amount decreases.
Alternatively, even when it becomes unnecessary, it is necessary to release the produced nitrogen gas to the outside by performing a standby operation and operating the PSA-type gas separation device. The present invention has been made to solve the above problems, and has as its object to reduce the power of a device having a low operating rate during normal operation.

[0006]

The nitrogen gas producing apparatus according to the present invention produces nitrogen gas from air by a PSA type gas separation apparatus and obtains nitrogen gas at a required pressure (in order to improve operation efficiency). A) a nitrogen gas compressor is provided downstream of the PSA-type gas separation device;

In producing nitrogen gas by the nitrogen gas producing apparatus, the pressure of the air supplied to the PSA type gas separating apparatus is set to about 5 kg / cm ² G at which the PSA type gas separating apparatus can efficiently separate gas. An operation method of the nitrogen gas producing apparatus, characterized by operating.

Here, the concept of the present invention will be described. In the PSA-type gas separation apparatus, the separation capacity is improved when the pressure of the supplied air is increased. However, when the pressure is 5 kg / cm ² G or more, the separation capacity is almost saturated, and does not increase much. Usually, when 5 kg / cm ² G time is 100%, 10 kg / cm ² G
It is about 113% at cm ² G.

However, conventionally, a PSA-type gas separation device requires two
Considering that the supply pressure of kg / cm ² G about nitrogen gas is lowered, was pressurized with an air compressor to about 10 kg / cm ² G in order to ensure the supply pressure (usually 7kg / cm ² G). As a result, the operating cost of the air compressor was enormous.

The present apparatus has been made in order to solve such a problem. The pressure of the air compressor is reduced to 5 kg / cm, which is the pressure at which the PSA type gas separation apparatus can efficiently separate gas.
^The operating cost is kept down to about ² G or by using the existing compressed air supply equipment if available, and the pressure drop is compensated for by a low flow rate nitrogen gas compressor installed downstream of the PSA gas separator. It is intended to realize reduction of the number.
In addition, by stopping the nitrogen gas compressor during the standby operation, it is possible to reduce the operating cost of a device having a low operation rate.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One example of the embodiment will be described with reference to FIG. The air is pressurized to about 5 kg / cm ² G by the air compressor 1, and the PSA gas separation device 3
Supplied to

The nitrogen gas produced by the PSA type gas separation device 3 passes through a pipe 4, is pressurized to a required pressure by a nitrogen gas compressor 5, and is passed through a pipe 6 to a nitrogen gas tank 7.
Supplied to

In this apparatus, the capacity of the air compressor 1 is
Instead of keeping the pressure at a minimum of about 5 kg / cm ² G, which is a pressure at which the gas separation apparatus 3 can efficiently separate gas, a predetermined capacity is achieved by increasing the capacity of the nitrogen gas compressor 5. It is possible to reduce the total operating cost of the compressor as compared with the conventional case.

Further, since the nitrogen gas compressor 5 can be stopped during the standby operation, the operation cost of the apparatus having a low operation rate can be reduced from the conventional method. Example 1 Nitrogen gas purity 99.9%, 7.5 from air
When producing nitrogen gas of kg / cm ² G and 340 Nm ³ / h and supplying it to a nitrogen gas tank.

In FIG. 1, the required flow rate of the air compressor 1 is 1,302 Nm ³ / h, from 1 kg / cm ² G to 5 kg / h.
Pressurize to cm ² G. The required production capacity of the PSA type gas separation device 3 is 340 Nm ³ / h, and 3 kg / cm ² G of nitrogen gas is produced. The required flow rate of the nitrogen gas compressor 5 is 34
0 Nm ³ / h, 7.5 kg of nitrogen gas of 3 kg / cm ² G.
Pressurize to kg / cm ² G.

In this case, the air compressor 1 has 132 kW,
The nitrogen gas compressor 5 uses 13 kW of power, and the compressor uses a total of 145 kW of power. When the operating rate is 50%, the compressor uses 139 kW of power on average.

A description will be given in comparison with the case of the prior art shown in FIG. In FIG. 2, the required flow rate of the air compressor 1 is 1, 1
48 Nm ³ / h, from 1 kg / cm ² G to 9.5 kg / cm
Pressurized to ² G.

The required production capacity of the PSA type gas separation device 3 is 340 Nm ³ / h, and 7.5 kg / cm ² G of nitrogen gas is produced. The air compressor 1 uses a power of 159 kW (the same applies when the operation rate is 50%).

As described above, in the case of the present invention, the power is 91% as compared with the prior art. When the operation rate is 50%, the power is 87% as compared with the conventional technology. Example 2 The purity of nitrogen gas in the case of Example 1 was 99.9.
%, But the purity of the nitrogen gas in this case is 99%.

Nitrogen gas purity from air: 99%, 7.5 kg /
cm ² G, if manufactures nitrogen gas 340 nm ³ / h supplied to a nitrogen gas tank. In FIG. 1, an air compressor 1
Required flow rate is 1,030 Nm ³ / h, and 1 kg / cm ²
Pressurized from G to 5 kg / cm ² G. The required production capacity of the PSA type gas separation device 3 is 340 Nm ³ / h, and 3 kg /
cm ² G of nitrogen gas is produced.

The required flow rate of the nitrogen gas compressor 5 is 340 Nm
³ / h, and 7.5 kg / cm ^{2 of} 3 kg / cm ² G nitrogen gas.
Pressurized to ² G. In this case, the air compressor 1
The kW, nitrogen gas compressor 5 uses 13 kW of power, and the compressor uses a total of 117 kW of power.

When the operation rate is 50%, the compressor uses an average power of 111 kW. A description will be given in comparison with the case of the prior art shown in FIG. In FIG. 2, the required flow rate of the air compressor 1 is 909 Nm ³ / h, and 1 kg / cm ² G
To 9.5 kg / cm ² G. The required production capacity of the PSA type gas separation device 3 is 340 Nm ³ / h;
5 kg / cm ² G of nitrogen gas is produced.

The air compressor 1 uses a power of 126 kW (the same applies when the operation rate is 50%). As described above, in the case of the present invention, the power is 93% as compared with the prior art. When the operating rate is 50%, the power is 88% as compared with the conventional technology.

[0024]

As described above, according to the present invention, the pressure in the air compressor is controlled to about 5 kg / cm ² G, which is the pressure at which the PSA type gas separation device can efficiently separate the gas. Since the pressure is increased to a required pressure by the nitrogen gas compressor, the power of the compressor is reduced, and the operating cost can be suppressed to about 91 to 93% as compared with the related art. Also,
Because the nitrogen gas compressor can be stopped during standby operation,
There is an effect that the operating cost of the device when the operation rate is low is further reduced by about several percent.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Air compressor, 2, 4, 6 ... Piping, 3 ... PSA type gas separation apparatus, 5 ... Nitrogen gas compressor, 7 ... Nitrogen gas tank.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshiyuki Kitano 1-1-2, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Toshio Kumazawa 25, Shintomi, Futtsu-shi, Chiba Tokyo Electric Power Company Inside Futtsu Thermal Power Plant (72) Inventor Koji Nakayama 25 Shintomi, Futtsu City, Chiba Prefecture Tokyo Electric Power Company Futtsu Thermal Power Plant Co., Ltd. (72) Inventor Koichi Hokari 25, Shintomi, Futtsu City, Chiba Prefecture Tokyo Electric Power Company Futtsu Thermal Power Plant (72) Inventor Nobuharu Nakagiri 25, Shintomi, Futtsu City, Chiba Prefecture Tokyo Electric Power Company Futtsu Thermal Power Plant (72) Invention No. 25 Shintomi, Futtsu City, Chiba Prefecture Inside the Futtsu Thermal Power Plant of Tokyo Electric Power Company (72) Inventor Masamitsu Takagi Prefecture Futtsu Shintomi 25 address TEPCO stock company Futtsu thermal power construction plant

Claims (2)

[Claims] When a nitrogen gas is produced from air by a PSA-type gas separation device and nitrogen gas at a required pressure is supplied, nitrogen gas is supplied downstream of the PSA-type gas separation device (to improve operation efficiency). A nitrogen gas producing apparatus comprising a gas compressor. 2. When nitrogen gas is produced by the nitrogen gas producing apparatus according to claim 1, the pressure of air supplied to the PSA-type gas separating apparatus is set to 5 kg / cm so that the PSA-type gas separating apparatus can efficiently perform gas separation. ^A method for operating a nitrogen gas producing apparatus, wherein the apparatus is operated at about ² G.