JPH0816582B2 - Carbon monoxide separation and purification equipment - Google Patents

Description

TECHNICAL FIELD The present invention separates carbon monoxide from a carbon monoxide-producing gas produced by oxidizing propane, butane, or the like, a byproduct gas of a steel mill, or the like. The present invention relates to a carbon monoxide separation / purification device.

[Conventional technology]

Because rich in carbon monoxide (CO) is reactive, it has been used as a raw material for synthetic chemistry, especially in recent years, are considered the most important carbon source among C ₁ chemistry. CO above
Is contained in a large amount in by-product gas from factories, including steelworks, and conventionally, at best, thermal energy is only recovered as fuel. However, an increase in demand for CO in recent years has led to the development of an apparatus for separating and recovering CO from the above-mentioned by-product gas. Recently, in view of the importance of CO as described above, an apparatus for separating and recovering CO from a CO raw material gas produced by oxidizing propane, butane, or the like has been proposed. These devices mainly use an adsorbent such as zeolite, and a device that selectively absorbs and collects CO with this adsorbent and a device that uses a COSORB liquid that selectively absorbs CO Two types of devices are used. However, the adsorption separation device using the above adsorbent (based on the PSA method) requires a high-speed switching valve in the device itself, and at the same time, switches the adsorbent by valve operation.
There is a drawback that there is no adsorbent that has perfect performance as it needs to be reused, and the life and performance cannot be completely reliable. Also, from the source gas
Since the CO recovery rate is low, the waste gas must be mixed with the raw gas again.
Since CO has to be separated and collected, there is a drawback that the running cost becomes high and the product CO becomes high.
In addition, there is a drawback that only high-purity CO can be obtained because only CO with a purity of about 98.0% can be obtained.

[Problems to be solved by the invention]

The apparatus for carrying out the Cossorb method has an advantage that it does not require a high-speed switching valve unlike the PSA apparatus described above, and for example, realizes the separation and recovery of CO by targeting a steelworks byproduct gas such as a converter gas. The composition of the converter gas is CO; 68-72vol
%, CO ₂ ; 13 ~ 17vol%, N ₂ ; 11 ~ 16vol%, H ₂ ; 0.8 ~ 1.3vol
%, O ₂ ; 0.1 vol% or less, and other than that, ammonia,
It contains trace components such as hydrogen sulfide and sulfur dioxide, dust and about 7% water. FIG. 3 shows an example of a cosorb apparatus for such a gas. In the figure,
Reference numeral 40 is a supply source of a raw material gas composed of a converter gas, and 41 is a compressor, which compresses and raises the pressure of the raw material gas. In this compressor 41, dust is collected in the oil of the compressor 41 and removed by a filter installed in an oil circulation system for cooling this oil. A brine cooler 42 preliminarily dehumidifies the pressurized raw material gas. 43 is an adsorption column filled with activated carbon that adsorbs and removes sulfur and ammonia in the raw material gas. Reference numeral 44 is a set of two adsorption columns filled with synthetic zeolite for adsorbing and removing water and carbon dioxide. The pair of suction cylinders 44 are alternately switched and used. Reference numeral 45 denotes an absorption tower, in which the raw material gas from which the above impurities have been removed and dehumidified is brought into countercurrent contact with the cosorb liquid flowing down from the upper part of the tower so that CO in the raw material gas is selectively absorbed by the cosorb liquid. . The Cossorb solution is a solution of CuAlCl ₄ dissolved in toluene, and selectively absorbs CO at a low temperature and emits CO at a high temperature by the following reaction.

47 is a heat exchanger, which selectively absorbs CO in the absorption tower 45
The cossorb liquid delivered from the bottom of 45 is heated by exchanging heat with the liquid delivered from the bottom of the stripping tower 45. The diffusion tower
45, the CO-absorbing cosorb liquid flowed down from the top of the tower, and contact with the toluene vapor generated by heating the reboiler 49,
CO Absorbs CO in COSORB solution. Here, the COSORB liquid that has diffused CO is cooled and regenerated from the bottom of the diffusion tower 46 via the heat exchanger 47 and the water cooling tower 48, and is returned to the top of the absorption tower 45. Waste gas is sent from the upper part of the absorption tower 45, cooled to −10 ° C. by the brine cooler 42 ′ to recover toluene, and sent to a piping system for blast furnace gas or the like. Then, the product CO (gas) is taken out from the upper part of the stripping tower 46. In this case, a small amount of CO ₂ , N ₂ , N ₂ ,
As O ₂ is dissolved, the product CO obtained from the diffusion tower 46 above
In addition to these, the trace amount of toluene in the cossorb solution is also mixed. 50 is a water cooling tower, which cools the above product CO and recovers toluene. 51 is a compressor, which boosts the pressure of the product CO. 52 is a brine cooler,
Cool the above product CO to -10 ° C and recover toluene.
Reference numeral 53 is a product CO storage tank, which appropriately sends the product CO.

However, in the above apparatus, a trace amount of impurities are inevitably mixed in the product CO, so that it is practically impossible to recover ultra-high purity carbon monoxide, and only about 98.0% is obtained. In addition, this device also has a drawback that the recovery rate of product CO is low.

The present invention has been made in view of such circumstances,
It is an object of the present invention to provide a carbon monoxide separation and purification apparatus capable of recovering ultra-high purity carbon monoxide at a high recovery rate.

[Means for solving problems]

In order to achieve the above object, the apparatus for separating and purifying carbon monoxide of the present invention is a compression unit for compressing a raw material gas containing carbon monoxide, a removing unit for removing carbon dioxide gas and water in the raw material gas, A heat exchange means for cooling the raw material gas, a hydrocarbon-based impure gas liquefaction remover for cooling and condensing the hydrogen carbonate-based impure gas in the raw material gas to liquefy, and a liquefaction removal of the hydrocarbon-based impure gas And a rectification column that liquefies carbon monoxide in the source gas due to the difference in boiling points and collects it at the bottom and separates the impure gas and discharges it from the top. A liquid nitrogen storage means for receiving and storing liquid nitrogen from the outside of the apparatus, and a first introduction path for guiding the liquid nitrogen in the liquid nitrogen storage means into the rectification column as a cold source for carbon monoxide conversion And the stored liquid at the bottom of the rectification column Of the hydrocarbon second to lead heat exchange impure gas liquefaction remover vaporized carbon monoxide produced by the vaporization of carbon as cooling source of the hydrocarbon-based impurity gas liquefaction
And an extraction path for extracting vaporized carbon monoxide that has been heat-exchanged by the hydrocarbon-based impure gas liquefaction remover as product carbon monoxide.

That is, this device is based on the cryogenic liquefaction separation method, and the raw material gas that has passed through the compression means, the removal means, and the heat exchange means is introduced into the heat exchange means and cooled to an ultralow temperature, and this is guided to the rectification column. , Inside of which is further cooled by the cold heat of liquid nitrogen supplied from the liquid nitrogen storage means,
While liquefying CO, the impure gas is removed as a gas,
Since this is discharged from the rectification tower and liquefied CO is vaporized and taken out, it becomes possible to recover ultrahigh-purity carbon monoxide. That is, since this device does not utilize the absorption and desorption of CO by heating and cooling of the cosorb liquid as in the above-mentioned cosorb device and the adsorption by the adsorbent as in the PSA device, the CO Dissolution of trace amounts of impure gases such as ₂ , N ₂ and contamination of impure gases due to poor adsorption of the adsorbent does not occur, and therefore the phenomenon of impaired purity of product carbon monoxide caused by these impure dissolved components Does not happen.

Next, the present invention will be described in detail based on examples.

〔Example〕

FIG. 1 is a block diagram of one embodiment of the present invention. In the figure, 1 is a raw material gas compressor, 2 is a drain separator, 3 is a Freon cooler, and 4 is a set of two adsorption tubes. The adsorption column 4 is filled with synthetic zeolite or activated carbon or a mixture of both, and adsorbs and removes H ₂ O, CO _{2 and the} like in the raw material gas compressed by the raw material gas compressor 1. 5
Is a raw material gas supply pipe for sending the raw material gas from which H ₂ O, CO _2, etc. have been adsorbed and removed. Reference numeral 6 denotes a heat exchanger, into which the compressed raw material gas from which H ₂ O, CO _2, etc. have been adsorbed and removed by the adsorption cylinder 4 is fed. Reference numeral 7 denotes a hydrocarbon-based impurity gas liquefaction remover that liquefies and removes a hydrocarbon-based impurity gas such as CH ₄ by cooling and condensation. Reference numeral 8 is a pipe for feeding the compressed raw material gas cooled by the heat exchanger 6 into the hydrocarbon-based impure gas liquefaction remover 7. Reference numeral 10 denotes an exhaust pipe extending downward from the hydrocarbon-based impure gas liquefaction remover 7, which discards the hydrocarbon-based impure gas in the raw material gas cooled and condensed by the remover 7. Reference numeral 25 is a heat exchanger provided in the middle portion. In the heat exchanger 25, a part of the compressed raw material gas fed by the branch pipe 26 branched from the raw material gas supply pipe 5 is used to cool the liquid (liquefied hydrocarbon-based impure gas) passing through the discharge pipe 10. It is cooled by and returned to the pipe 8 by the return pipe 27 as shown by the arrow. Reference numeral 11 denotes a rectification column, which is composed of a condenser section 12 having a built-in condenser 28 and a medium pressure column section 13, and a large number of rectification shelves 14 are arranged in the medium pressure column section 13. . A low temperature raw material gas feed pipe 8a extending from the hydrocarbon-based impure gas liquefaction remover 7 is connected to the heater pipe 25a in the tower section 13 so as to feed the raw material gas cooled to a low temperature. I'm running. The tip of the heater pipe 25a is the tower 1
It extends through 3 to the outside and bends upward from there to the tower 1
In the central part of 3, it communicates with the inside of the tower 13, and the heater pipe 25a
The low temperature raw material gas passing through is discharged into the tower section 13. In this tower section 13, a part of CO in the raw material gas is liquefied and flows downward and collects at the bottom, and H ₂ , N _{2 and} other impure gases and C
The rest of O rises above the tower section 13 in a mixed gas state. The liquid CO accumulated at the bottom of the tower 13 exchanges heat with the raw material air flowing through the heater pipe 25a to partially vaporize it, and this vaporized gas is taken out from the take-out pipe 37, and the hydrocarbon-based impurities are impure. After being guided to the gas liquefaction remover 7 and exerting the action as cold inside it, it is further guided to the inside of the heat exchanger 6 where it also acts as cold and becomes CO gas at room temperature, and becomes the product from the main pipe 37a. It is coming out as CO gas. Reference numeral 15 is a first reflux liquid pipe that connects the upper part of the tower section 13 and the condenser 28 in the dephlegmator section 12, and sends the mixed gas rising above the tower section 13 into the condenser 28. It is supposed to enter. Reference numeral 15a is a shielding plate, which forms a flow path for guiding the above mixed gas to the first reflux liquid pipe 15, and the movement of the mixed gas flowing through this flow path causes the impure gas (H ₂ , N ₂ ) accumulated at the top of the tower. Is mixed with the mixed gas to prevent impure gas from staying at the top of the column. In the condenser 28, CO is liquefied due to the difference in boiling points, and N ₂ , H _{2 and the} like are removed in a gaseous state through a waste gas pipe 30 extending upward from the condenser 28. 16 is from the bottom of the condenser 28 to the tower 13
Is a second reflux liquid pipe extending into the upper part of the, and guides the liquefied CO accumulated in the bottom of the condenser 28 into the liquefied CO reservoir 38,
A part of it is sent from the pipe 39 to the liquid CO storage tank 100 for storage, and at the same time, the rest is passed through the pipe 16a and the tower section 13
It is made to flow down as a reflux liquid in the receiving tray 17 inside. A liquid level controller 22a controls the valve 39a by the liquid level of the liquefied CO reservoir 38 to control the amount of liquid CO fed into the liquid CO storage tank 100. Reference numeral 101 is a liquid CO inflow pipe, which is provided with a valve 102 and a liquid delivery pump P which are controlled by a liquid level controller 21 which keeps the liquid level in the tower 13 constant.
The stored liquid CO at the bottom of the rectification column section 13 is supplied to the liquefied CO reservoir 38. In this case, even if the supplied liquid CO is in a gas-liquid mixture state, it once enters the liquefied CO reservoir 38 and then flows down as a reflux liquid into the rectification column section 13, so that the reflux liquid is bubbled. There is an advantage that the phenomenon does not occur and the material flows down stably. Then, the liquefied CO that has flowed down into the tray 17 of the rectification tower tower 13 overflows and flows downward in the tower section 13, and the raw material gas fed into the tower section 13 from the low temperature raw material gas feed pipe 8a. In countercurrent contact with the CO2, the CO2 in the raw material gas is liquefied by the heat of vaporization and the impure gas with a low boiling point is transferred upward to purify CO. Reference numeral 18 denotes a liquid nitrogen storage tank which receives supply of liquid nitrogen from the outside of the device and stores the liquid nitrogen. , The cold source of the condenser 28 in the partial condenser unit 12. 36a is the input liquid nitrogen. 31
Is a delivery pipe for delivering vaporized liquefied nitrogen after finishing the action as cold in the dephlegmator section 12 of the rectification tower 11,
It is in communication with the N ₂ gas extraction pipe 32a, and after vaporized liquefied nitrogen is heat-exchanged through the heat exchanger 6, it is sent out from the N ₂ gas extraction pipe 32a to be used. There is. Control valve 34 provided in the introduction pipe 32
Is controlled by the liquid level controller 22 so that the liquid level of the liquid nitrogen in the dephlegmator section 12 of the rectification column 11 is kept at a constant level. The heat exchanger 6 and the rectification column 11 are housed in a vacuum heat insulating container as shown by the alternate long and short dash line. Further, 103 is a back-up system line equipped with an evaporator 104 and a valve 105, and when the rectification column line fails,
Alternatively, when the amount of product CO is insufficient in the rectification tower line alone, the liquid CO in the liquid CO storage tank 100 is evaporated by the evaporator 104 and sent to the main pipe 37a, and the supply of product CO gas is not interrupted. Or make sure that there is no shortage of product CO. The above liquid CO storage tank 10
Liquid CO can be taken out from 0 as a product, and
It is also possible to supply liquid CO from the outside of the device and cause it to flow down into the receiving tray 17 as a reflux liquid to realize an early operation when the device starts up.

This device is, for _{example, CO; 69.93vol%, H 2} ; 30vol%, C
C of H ₄ ; 0.03vol%, CO ₂ ; 0.03vol%, N ₂ ; 0.01vol%
The product CO is manufactured as follows for O source gas (manufactured by oxidation of propane and butane). That is, the raw material gas compressor 1 compresses the raw material gas, the drain separator 2 removes the water content in the compressed raw material gas, and the CFC cooler 3 further cools the raw material gas. Adsorbs and removes H ₂ O and CO ₂ in gas. Then, a part of the raw material gas from which H ₂ O and CO ₂ have been adsorbed and removed is sent to the heat exchanger 6 which is cooled by the nitrogen gas from the rectification tower 11, the waste gas and the product CO gas, and the ultra low temperature is reached. At the same time as the cooling, the balance is fed into the heat exchanger 25 cooled by the hydrocarbon impure gas liquefaction and cooled to an ultra-low temperature. Then, these two gases are merged and further introduced into the hydrocarbon-based impure gas liquefaction remover 7 to exchange heat with the product CO gas, and passed through the heater pipe 25a at the bottom of the rectification column 11 to the rectification column. Introduced into the tower section 13 of 11 (raw material gas temperature of about -170
℃). Then, the CO in the raw material gas is liquefied and stored as liquid CO at the bottom of the tower section 13 by making countercurrent contact with the overflow liquefied CO from the tray 17. At this time, the H ₂ and N ₂ gases in the raw material gas rise upward in the tower section 13. Further, a part of CO in the raw material gas is not liquefied but rises as it is along with the above H ₂ and N ₂ gases and the like. The mixed gas of rising H ₂ , N ₂ and CO is the first
Is sent from the reflux liquid pipe 15 to the condenser 28 of the rectification column 11,
Here, only the CO gas is liquefied due to the difference in boiling point, and is fed into the liquefied CO reservoir 38 as the reflux liquid through the second reflux liquid pipe 16, and the liquid CO storage is performed by opening / closing the valve 39a and adjusting the opening degree. In the tank 100 or in the rectification tower 11, the saucer 1 of the tower section 13
7 or both. On the other hand, H ₂ and N ₂ gas is taken out from the upper part of the condenser 28 by a waste gas pipe 30,
The heat is exchanged with the raw material gas in the heat exchanger 6 and released into the atmosphere. Then, the liquid CO accumulated at the bottom of the tower section 13 in the rectification tower 11 is sequentially vaporized by the action of the heater pipe 25a, taken out from the take-out pipe 37, the hydrocarbon-based impure gas liquefaction remover 7, heat exchange. It is taken out from the main pipe 37a as normal temperature product CO gas through the container 6.

In this way, in this device, the raw material gas from which the impurities have been removed in the adsorption column 4 is cryogenic liquefied and separated in the rectification column 11 to produce liquefied CO
Therefore, the purity of the liquefied CO product obtained is extremely high. Moreover, even if the demand amount of the product liquefied CO fluctuates, by the control action of the liquid level controller 22 in the dephlegmator section 12 of the rectification column 11, the liquid nitrogen storage tank 18 causes the rectification column 11 to move. The supply amount of liquid nitrogen supplied to the partial condenser unit 12 is automatically controlled. Therefore, it is possible to automatically and promptly respond to the fluctuation of the demand amount, and at the same time, there is no variation in purity. In particular, this device constantly guides a part of the raw material gas in the rectification tower 11 into the condenser 28 of the dephlegmator section 12 in the rectification tower 11 and liquefies it. After a predetermined amount has accumulated, the liquefied CO that is generated thereafter will always return to the inside of the tower section 13 of the rectification tower 11 as a reflux liquid. Therefore, variations in product purity due to intermittent supply of reflux liquid from the condenser 28 (Discontinuation of the flow of the reflux liquid causes the reflux liquid to disappear in the rectification shelf, leading to a gas blow-through phenomenon and lowering the product purity. , And the purity recovers when the flow is resumed), and product liquefied CO of stable purity can always be supplied.

In addition, when the demand volume increases significantly that cannot be controlled by the liquid level controller 22, or when the product CO gas cannot be obtained from the rectification tower 11 due to a failure of the rectification tower line, etc. In addition, the backup system line 103 is activated to directly vaporize the liquid CO in the liquid CO storage tank 100.
Is vaporized in the main pipe 37a as product CO gas, which reduces the purity of the product CO gas when a large increase in demand occurs, and avoids the CO supply of the product. CO gas can be supplied.

FIG. 2 shows another embodiment. In this device, the tip of a liquid CO feed pipe 101 extending from the bottom of the rectification column section 13 is connected to a pipe 39 extending from the liquid CO storage tank 100 to the rectification column section 13. Other parts are the same as those of the apparatus shown in FIG.

As a result of such a configuration, a liquid feed pump for the liquid CO feed pipe 101 becomes unnecessary, and the effect of reducing the number of parts can be obtained.

It should be noted that, in the above-mentioned embodiment, a material gas with a small amount of CO ₂ and O ₂ components (the total amount of both is 0.1% or less) is used, but a material gas with a large amount of CO ₂ and O ₂ components is used as the material gas. In order to remove the O ₂ component, a catalyst tower (Pd, Pt, Ni, etc.) is installed after the source gas compressor 1 to remove the O ₂ component, and the O ₂ component is changed to CO ₂ or H ₂ O or both, and In order to remove the CO ₂ component, it is preferable to provide the chlorofluorocarbon cooler 3 with a refrigerator for converting CO ₂ into liquefied CO ₂ .

〔The invention's effect〕

Since the apparatus for separating and purifying carbon monoxide of the present invention is configured as described above, it is possible to efficiently produce ultra-high-purity carbon monoxide. Moreover, since this device uses liquid nitrogen supplied to the liquid nitrogen storage means from outside the device as a cold source for the rectification column or the like, it does not require a rotating device such as an expansion turbine, and therefore, the rotating device This eliminates the need for troublesome operations such as operation and maintenance, and also enables downsizing of the entire device.

[Brief description of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is a block diagram of another embodiment, and FIG. 3 is a block diagram of a conventional example. 1 ... Raw material gas compressor, 4 ... Adsorption column, 6 ... Heat exchanger, 7 ... Hydrocarbon-based impure gas liquefaction remover, 8a ... Inlet pipe, 11 ... Fractionation tower, 18 ... Liquid nitrogen storage tank, 32 ...... Introduction pipe

Claims (1)

[Claims] 1. A compression means for compressing a raw material gas containing carbon monoxide, a removing means for removing carbon dioxide gas and moisture in the raw material gas, a heat exchange means for cooling the raw material gas, and A hydrocarbon-based impure gas liquefaction remover for cooling and condensing hydrogencarbonate-based impure gas in the raw material gas, and a raw material gas for guiding the raw material gas through the hydrocarbon-based impure gas liquefaction remover into the rectification column A supply channel, a rectification column that liquefies carbon monoxide in the raw material gas due to the difference in boiling point and collects it at the bottom to separate the impure gas and discharges it from the top, and receives liquid nitrogen from outside the device and stores it. A liquid nitrogen storage means, a first introduction path for guiding the liquid nitrogen in the liquid nitrogen storage means into the rectification column as a refrigeration source for carbon monoxide, and a liquid carbon monoxide stored at the bottom of the rectification column. The vaporized carbon monoxide produced by vaporization is converted to hydrocarbon. The is leading heat exchanger as cooling source of impure gas liquefaction to the hydrocarbon-based impurity gas liquefaction remover 2
And an extraction path for extracting vaporized carbon monoxide that has been heat-exchanged by the hydrocarbon-based impure gas liquefaction remover as product carbon monoxide.