JPS6051523A - Recovery of power for preparing gas - Google Patents

Abstract

PURPOSE:To set an adsorbent to an optimum low temp. condition in reduced power cost, in a product gas supply system from each adsorbing/desorbing tower, by recovering power from an adsorbing process while cooling stock gas by low temp. gas after recovery and the outlet gas of an adsorbing tower. CONSTITUTION:Each of parallelly arranged adsorbing/desorbing towers 1, 2 is acted as an adsorbing tower when a stock gas charging compressor 3 is cooperated and acted as a desorbing tower when a suction vacuum pump 5 is cooperated. By utilizing high temp. and high pressure product gas 7 after adsorption is finished, power is recovered by a power recovery apparatus 11 and, by utilizing gas lowered in the temp. thereof in an expansion process after recovery, the inlet and outlet of the stock gas charging compressor 3 and cooled by a cooler 4. In addition, the cooler 4, which performs heat exchange of the adsorbing/desorbing towers 1, 2 by utilizing temp. lowering due to heat adsorption at the time of gas desorption, is provided and the inlet or outlet of the stock gas charging compressor 3 is similarly cooled.

Description

[Detailed description of the invention] The present invention relates to a power recovery method for gas production.

In gas production using adsorption/desorption agents, the gas is pressurized during the gas adsorption process, and the adsorbed gas is desorbed by suctioning to below atmospheric pressure during the gas desorption process, and pure gas is separated.0 Figure 1 shows the conventional method. Give an example.

The raw material gas 8 is pressurized and supplied to the adsorption/desorption tower 1 in the adiabatic tank 10 by the raw material gas forcing compressor 3. Specific gases are selectively adsorbed in the adsorption/desorption tower 1, and the residue becomes the product gas 7. will be supplied. At this time, the adsorption temperature condition is set by the cooler 4. The adsorption tower 1, which has completed adsorption, and the desorption tower 2, which has completed suction desorption by the suction vacuum pump 5, are connected by opening the pressure equalization valve 6 to equalize the pressure. Get into the process. During this time, product gas 7 is not supplied.

After completing the adsorption, the column 1 is connected to the suction vacuum pump 5 after the pressure equalization process, and returns to its original state by suctioning and desorbing the adsorbed gas 8. At the same time, in this process, adsorption is performed in another adsorption/desorption tower 2, and the product gas 7 is supplied.

Adsorbents usually differ in the type and selectivity of adsorbed gases and adsorption/desorption performance depending on the temperature and pressure conditions.
In the above-mentioned conventional method, the initial price and operating cost of the raw material gas push compressor 3 for adsorption and the suction vacuum pump 5 for desorption are large, and most of the costs are Reducing these power costs has become a major issue.

Furthermore, since the working fluid is moved intermittently, there is also a drawback that supply of the product gas 7, heat utilization, and power recovery cannot be carried out continuously.

In a pressure swing type gas production method, the present invention recovers power by using the pressurizing force and heat generated during gas adsorption, and adsorbs raw material gas by using the power recovery device and the low temperature gas at the outlet from the desorption tower. The present invention provides a power recovery method for gas production that can cool the system and bring it close to the optimal low-temperature operating conditions of the adsorbent.

That is, the present invention, when producing product gas from raw material gas using a gas adsorbent, uses adsorption/desorption towers in parallel that continuously repeat the process of adsorbing the raw material gas with a compressor and desorbing it with a vacuum pump. If multiple units are installed, each unit is operated with a phase difference in the above process, and a power recovery device is connected to the product gas supply system from the winter clothes/desorption tower to reduce the pressure and heat generated by the high-pressure gas during the adsorption process. A power recovery method for gas production, characterized in that power is recovered and a raw material gas intake or outlet system to the compressor is cooled by exhaust gas from the power recovery device and outlet gas from the desorption tower. It is related to.

The present invention is characterized by the following points.

1) Continuous power recovery and heat utilization are possible by installing multiple adsorption/desorption towers.

2) The high pressure gas and heat generated during the adsorption process are used to recover power from a recovery turbine, etc.

3) The low-temperature gas at the outlet of the power recovery device or desorption tower can be used to cool the raw material intake gas and operate under the optimal adsorption/desorption conditions for the low-temperature adsorbent. 4) The outlet of the power recovery device or desorption tower The raw material gas compressor inlet is cooled using the low-temperature gas.

FIG. 2 is a diagram showing an embodiment of the present invention, in which there is one adsorption/desorption tower.

The adsorption/desorption towers 1 and 2 act together with the adsorption tower (7) when the feed gas forced compressor 3 is operated, and the suction vacuum pump 5
When linked together, it acts as a desorption tower.

When the feed gas forced compressor 3 and the adsorption/desorption tower 1 are connected, a specific gas is selectively adsorbed by the adsorption/desorption tower 1,
The remainder comes out as product gas 7.

On the other hand, the adsorption/desorption tower 2 containing the remaining residue, which has been completely adsorbed, is sucked by the suction vacuum pump 5, and the adsorbed gas 9 is desorbed and released.

Gas that is not adsorbed by the adsorbent remains in the adsorption/desorption towers 1 and 2, but this is mixed and pressure-equalized in the adsorption/desorption towers 1 and 2 by the pressure equalization valve 6, and the product gas purity is increased before being absorbed and desorbed. These adsorbed gases 9 are suctioned, desorbed and eliminated from the tower 2 by a suction vacuum pump 5.

When desorption is completed in the adsorption/desorption tower 2, the suction vacuum pump 5 is switched to the raw material gas forced compressor 3, and the original cycle returns.

The adsorbent has better selective absorption when operated at a relatively low temperature. The winter clothing/desorption towers 1 and 2 are installed within a heat insulating structure 10.

Furthermore, as a property of the adsorbent, when gas is adsorbed, the temperature is high due to heat generation, and when gas is desorbed, the temperature is low due to heat absorption. For this reason, the temperature of the product gas 7 during adsorption is high, so the power recovery device 11 recovers the power by utilizing this relatively high temperature and high pressure product gas 7.
The gas that has become low temperature during the expansion process after the power recovery device 11 is used to cool the raw material gas forced compressor 3 through a cooler 4, which is a heat exchanger, for example.

Note that the cooler 4 can also be installed to cool the outlet of the compressor 3.

Furthermore, by utilizing the temperature drop due to heat absorption during gas desorption, a cooler 4 is installed at the outlet of the adsorption/desorption tower 1.2 to perform heat exchange, and the raw material gas forced compressor 3 or outlet is similarly installed. Cooling.

Further, during the pressure equalization process of the adsorption/desorption tower 1.2, the raw material gas 8 entering can also be cooled.

As mentioned above, when there is one adsorption/desorption tower 1 and one adsorption/desorption tower 2,
During the cycle, there is a pressure equalization process in the suction/deMation towers 1 and 2, so the product gas 7 is intermittently discharged. Therefore, as an example of constantly supplying working fluid, multiple adsorption/desorption towers (A) to (H) are installed as shown in Figure 3, and the phase of each tower (A) to (H) is adjusted. Shift and operate,
The number of columns (A) to (H) may be selected so that the intermittent time during pressure equalization is covered by the columns (A) to (H).

Figure 4 shows the continuous working fluid supply method for winter clothing and equipment in the case of Figure 3.
It is a figure showing the operation mode of a desorption tower.

In Figure 3.4, each group (A), (B), ... (H
) with adsorption valves (AI), (Bt), ... (Ht)
and detachment valve (A2)l (B2)l...(Hl)
Connect. Each adsorption valve (At) to (Ht) is connected to the raw material gas compressor 3, and each desorption valve (A2) to (Hl) is connected to the cooler 4 by suction vacuum pumps (5A), (5B), (sc
) is connected to

Adsorption valves (A1) to (Hl) in each group (A) to (H)
1 Desorption valves (A2) to (Hl) and pressure equalization valves (6A), (
6B).

If (6C) and (60) are properly adjusted by a switching method, the intermittent flow period can be eliminated as shown in FIG.

Using the continuously supplied product gas 7, the power recovery device 11 performs expansion work and recovers power. The low-temperature product gas passes through the cooler 4 to the raw material gas inlet system 1.
It is also possible to cool the raw material gas outlet system by changing the installation position of the cooler 4. Similarly, the raw material gas inlet system can be cooled by using the continuously drawn low-temperature desorption gas. 14 or cool the outlet system.

In addition, each pump (5A), (5B), (sc) is driven by a morph (M) and gears (G1), ((h), (Gs) and linked together.

According to the present invention described in detail above, the following effects can be achieved.

1) The power recovery device 11 performs energy conversion and recovers power using the heat generated and pressurized force during the adsorption process of the product gas 7 that is continuously supplied.

2) The expansion work is performed by the power recovery device 11, and the low-temperature product gas 7 is used to cool the raw material suction gas pressure machine 3 or output 1, and the required power of the compressor 3 is reduced. (In addition, cooling the inlet of the compressor 3 is more effective in significantly reducing the power required for compression*3 than cooling the outlet.) At the same time, it provides low-temperature conditions that match the adsorption/desorption characteristics of the low-temperature adsorbent, improving adsorption/desorption performance and reducing the amount of adsorbent waste. Since the raw material intake gas 8 is cooled by the low-temperature desorption gas 9, the power required for the intake gas compression 4133 is reduced. Furthermore, the optimum conditions for the low-temperature adsorbent can be provided without requiring the power of a separate cooler 4.

As described above, by performing power recovery and cooling using the product gas 7 and cooling using the desorption gas 9, and by providing a thorough method of power recovery and heat utilization, it is possible to reduce running costs and reduce the running cost per unit of power source (1 kg of product gas). power costs) can be reduced.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a conventional gas production method, FIG. 2 is a diagram showing one embodiment of the method of the present invention, FIG. 3 is a diagram showing another embodiment of the method of the present invention, and FIG. This is a diagram showing the driving mode in the case of Figure 3.

Claims (1)

[Claims] When producing product gas from raw material gas using a gas adsorbent, multiple adsorption/desorption towers are installed in parallel to continuously repeat the process of adsorbing raw material waste with a compressor and desorbing it with a vacuum pump. The system is operated by creating a phase difference in the above process, and a power recovery device is connected to the product gas supply system from the valley adsorption/desorption tower to recover the power from the pressurized gas and heat generated during the adsorption process. . A power recovery method for gas production, characterized in that a raw material gas inlet system or outlet system to the compressor is cooled by exhaust gas from the power recovery device and outlet gas from the desorption tower.