JPH0816581B2 - Carbon monoxide separation and purification equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention separates carbon monoxide from a carbon monoxide-producing gas produced by oxidizing propane, butane, or the like, a by-product gas of an iron 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. Further, recently, in view of the importance of CO as described above, an apparatus for separating and recovering CO from a CO source gas produced by oxidizing propane, butane, etc. has been proposed. An adsorbent such as zeolite is mainly used for these devices, a device for concentrating and collecting CO by this adsorbent, and a COSOB (COSO) that selectively absorbs CO
Two types of equipment are used, one that uses the RB solution. However, the adsorption-separation device (based on the PSA method) that uses the above-mentioned adsorbent requires a large number of valves in the device itself, and at the same time, it is necessary to switch the adsorbent by valve operation and recycle it. Is complicated, and complicated valve operation is required. In addition, since the recovery rate of CO from the raw material gas is low, it is necessary to mix waste gas with the raw material gas again to separate and collect CO, which has a drawback that the running cost becomes high and the product CO becomes high. are doing. In addition, there is a drawback that only high-purity CO can be obtained because only CO with a purity of about 99.5% 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 large number of valves unlike the PSA apparatus described above. For example, CO separation and recovery is carried out for steelworks by-product gas such as converter gas. The composition of the converter gas is CO; 68-72 vol%, C
O ₂ ; 13 to 17 vol%, N ₂ ; 11 to 16 vol%, H ₂ ; 0.8 to 1.3 vol%, O ₂ ;
It is 0.1 vol% or less, and in addition to that, it contains trace components such as ammonia, hydrogen sulfide, and sulfur dioxide, dust, and about 7% of water. FIG. 3 shows an example of a cosorb apparatus for such a gas. In the figure, 40 is a raw material gas composed of a converter gas, and 41 is a compressor, which compresses the raw material gas to increase its pressure. 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. 42
Is a brine cooler that preliminarily dehumidifies the pressurized raw material gas. 43 is an adsorption cylinder filled with activated carbon, which is sulfur in the raw material gas,
Adsorb and remove ammonia. 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 above cosoave liquid is changed to toluene
It is a solution of CuAlCl ₄ , and the following reaction
It selectively absorbs CO at low temperatures and emits CO at high temperatures.

47 is a heat exchanger, which selectively absorbs CO in the absorption tower 45
The Cosorb liquid delivered from the bottom of 45 is heated by exchanging heat with the liquid delivered from the bottom of the stripping tower 46. The diffusion tower
46, the CO-absorbing cosorb liquid flowed down from the top of the tower, 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 , H ₂ ,
As O ₂ is dissolved, the product CO obtained from the diffusion tower 46 above
These are mixed. 50 is a water cooling tower,
The above product CO is cooled and toluene is recovered. 51 is a compressor, which boosts the pressure of the product CO. 52 is a brine cooler, which collects toluene obtained by cooling the above product CO to -10 ° C. Reference numeral 53 is a product CO storage tank, which appropriately sends the product CO.

However, in the above apparatus, trace amounts of impurities are inevitably mixed in the product CO, so that it is practically impossible to recover ultrahigh-purity carbon monoxide, and only about 99.5% 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 raw material gas supply path for guiding the raw material gas that has passed through the heat exchange means into the condenser of the condenser built-in cooler, and a monoxide in the raw material gas due to a difference in boiling point. A rectification column that liquefies carbon and stores it inside to separate and discharge impure gas, liquid nitrogen storage means that receives liquid nitrogen from outside the device and stores it, and liquid nitrogen inside this liquid nitrogen storage means Introducing path leading to the rectification column as a cold source for carbon monoxide liquefaction, withdrawal path for taking out the stored liquefied carbon monoxide in the rectification column as a product carbon monoxide as it is or in a gaseous state, and in the rectification column Of stored liquefied carbon monoxide Corresponding to the control means for controlling the liquid level of the stored liquefied carbon monoxide to a constant level by controlling the amount taken out to the take-out passage, and the upper layer of the liquid level of the stored liquefied carbon monoxide in the rectification column. A configuration is provided in which a discharge passage is provided for discharging the hydrocarbon-based liquefied gas floating from an upper part of the liquid surface of the stored liquefied carbon monoxide from the rectification column to the outside of the system.

That is, this apparatus is a 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, cooled to an ultralow temperature, and guided to the rectification column.
Cooling with the cold heat of liquid nitrogen further supplied from the liquid nitrogen storage means inside it to liquefy CO in the raw material gas, remove impure gas as a gas, and at the same time discharging it from the rectification column, Since the liquefied CO is taken out as it is or after being vaporized, ultrahigh-purity carbon monoxide can be recovered. That is, this device
Since CO absorption, emission of CO by heating and cooling of co-sorb liquid like the above-mentioned co-sorb device is not used, or absorption by adsorbent like PSA device is not used, CO ₂ , N ₂ etc. in the co-sorb liquid Does not dissolve the trace amount of impure gas, does not mix the impure gas due to poor adsorption of the adsorbent, and thus does not cause the phenomenon of impairing the purity of the product carbon monoxide due to the impure dissolved components. In addition, the stored liquefied carbon monoxide in the rectification tower is controlled by controlling the amount of the stored liquid liquefied carbon monoxide (the stored liquid liquefied carbon monoxide as it is or in a gaseous state to be taken out as product carbon monoxide) in the extraction passage. A control means for controlling the liquid level of carbon to a constant level, and extending from the portion of the rectification column corresponding to the upper layer of the liquid level of the stored liquefied carbon monoxide in the rectification column, Since the discharge path for discharging the hydrocarbon-based liquefied gas floating in the upper layer is provided outside the system, the liquid level of the stored liquefied carbon monoxide in the rectification column can be accurately controlled by the control means, and The hydrocarbon-based liquefied gas floating above the liquid surface of the stored liquefied carbon monoxide can be discharged from the discharge path to the outside of the system, and the product carbon monoxide having a higher purity can be taken out.

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 11 denotes a rectification tower, which comprises a condenser 28 built-in condenser 28 and a medium pressure tower section 13, and a large number of rectification shelves 14 are arranged in the medium pressure tower section 13. . A low temperature raw material gas feed pipe 29 extending from the heat exchanger 6 is opened in the tower portion 13 to feed the raw material gas cooled to an ultra low temperature. In the tower section 13, CO
Is partially liquefied and flows downward, and the impure gas such as H ₂ and N ₂ and the rest of CO rise above the column 13 in a mixed gas state.
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 mixed gas to the first reflux liquid pipe 15, and the impure gas (H ₂ , N ₂ ) accumulated at the top of the tower is removed by the movement of the mixed gas flowing in this flow path. Prevent the impure gas from staying at the top of the column by accommodating the mixed gas. In the condenser 28, CO is liquefied due to the difference in boiling point,
N ₂ , H _{2 and the} like are removed in a gaseous state from the condenser 28 through a waste gas pipe 30 extending upward. Reference numeral 16 denotes a second reflux liquid pipe extending from the lower portion of the condenser 28 into the upper portion of the tower portion 13, and the liquefied CO accumulated at the bottom portion of the condenser 28 flows down as a reflux liquid into a tray 17 in the tower portion 13. It is getting to let you. The liquefied CO that has flowed down into the tray 17 overflows and flows downward in the tower portion 13, and comes into countercurrent contact with the raw material gas fed into the tower portion 13 from the low temperature raw material gas feed pipe 29, CO gas in the raw material gas is liquefied by the heat of vaporization. Numeral 8 is a hydrocarbon liquefied gas discharge pipe, which discharges hydrocarbon liquefied gas 9a such as CH ₄ floating in a layer due to the difference in specific gravity to the upper layer of the liquefied CO9 accumulated at the bottom of the rectification tower section 13 to the outside of the system. It is becoming like this. 18 is a liquid nitrogen storage tank that receives the supply of liquid nitrogen from outside the device and stores it, and sends the liquid nitrogen inside to the separator section 12 of the rectification column 11 via the introduction path pipe 32, The condenser 28 in the partial condenser unit 12 serves as a cold source. 36a is the input liquid nitrogen. 31 is a rectification tower 11
A delivery pipe for delivering vaporized liquefied nitrogen after ending the action as cold in the dephlegmator section 12 of No. ₂ , which is in communication with the N ₂ gas take-out pipe 32a, and vaporizes liquefied nitrogen through the heat exchanger 6. After passing through it for heat exchange, it is sent out from the N ₂ gas extraction pipe 32a to the outside for use. Reference numeral 19 is an extraction pipe for taking out liquefied CO9 accumulated in the bottom portion of the tower portion 13 of the rectification tower 11 as product CO. 36
Is a storage tank for product CO, and from this tank 36 product CO
Are taken out as appropriate. A control valve 20 is provided on the take-out pipe 19.
Is provided. A liquid level controller 21 controls the control valve 20 according to the liquid level so that the liquid level of the stored liquefied CO9 at the bottom of the rectification column section 13 is kept at a constant level. Further, the control valve 34 provided in the introduction pipe 32 is also 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 maintained at a constant level. It is becoming like this. In addition, the heat exchanger 6 rectification tower 11
Are housed in a vacuum heat insulation container as indicated by the one-dot chain line in the figure.

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, 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 and the waste gas from the rectification column 11 to be cooled to an ultralow temperature. Then, the raw material gas cooled to the ultra low temperature is supplied to the tower section 13 of the rectification tower 11.
The liquefied CO is liquefied at the bottom of the tower 13 by liquefying the CO in the source gas by countercurrently contacting the overflowed liquefied CO from the pan 17
Collect as 9. At this time, the H ₂ and N ₂ gases in the raw material gas are
The tower section 13 rises upward. Further, a part of CO in the raw material gas is not liquefied but rises as it is along with the H ₂ and N ₂ gases as it is. The mixed gas of the ascending H ₂ , N ₂ and CO is fed from the first reflux liquid pipe 15 to the condenser 28 of the rectification column 11, where only the CO gas is liquefied due to the difference in boiling points. , And returns to the receiving tray 17 of the tower section 13 in the rectification column 11 via the second reflux liquid pipe 16 as the reflux liquid. On the other hand, the H ₂ and N ₂ gases are
Is taken out by the waste gas pipe 30 from the upper part of the heat exchanger 6 and exchanges heat with the raw material gas in the heat exchanger 6 and is released into the atmosphere. Then, the liquefied CO 9 accumulated at the bottom of the tower section 13 in the rectification tower 11
Is taken out as a liquefied product from the product liquefied CO take-out pipe 19, is once stored in the storage tank 36, and is then appropriately used. The hydrocarbon-based liquefied gas such as CH _{4 in} the upper layer of the liquefied CO 9 is discharged out of the system through the exhaust pipe 8.

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, the liquid nitrogen storage tank 18 separates the fraction of the rectification column 11 from the liquid nitrogen storage tank 18 by the control action of the liquid level gauge 22 in the partial condenser 12 of the rectification column 11. The supply amount of liquid nitrogen supplied to the compressor 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 apparatus constantly guides a part of the raw material gas in the rectification column 11 into the condenser 28 of the fractionation column part 12 in the rectification column 11 to liquefy it, so that the liquefied CO 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. , The purity recovers when the flow is resumed), and stable product liquefied CO can always be supplied.

FIG. 2 shows another embodiment of the present invention. In this device, the raw gas passed through the heat exchanger 6 is passed through the bottom storage liquefied CO9 of the rectification tower column 13 through the low temperature liquefied gas feed pipe extension 2
The liquefied OC9 is heated and vaporized by being guided to the inside of 5a, and the vaporized CO
Is taken out from the take-out pipe 37 as the product CO gas, and the liquefied CO generated in the condenser 28 is guided into the liquefied CO reservoir 38 so that it can be taken out from the pipe 39 as the product liquefied CO. A liquid level gauge 22a controls the valve 39a by the liquid level of the liquefied CO reservoir 38 to keep the liquid level constant. The other parts are substantially the same as the device of FIG.

This device has an effect that both liquid CO and gaseous CO can be supplied as product CO.

In addition, although the above embodiment shows the liquid removal and both the liquid and the gas removal, it is also possible to perform the gas removal in which only the CO gas in the tower section 13 is taken out as the product gas.

〔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 In addition to supporting complicated labor such as operation and maintenance, it becomes possible to downsize the entire device. Further, the stored liquefied carbon monoxide in the rectification column is controlled by controlling the amount of the stored liquefied carbon monoxide taken out to the take-out path (the stored liquid liquefied hydrogen monoxide is taken out as product carbon monoxide as it is or in a gaseous state). A control means for controlling the liquid level of carbon to a constant level, and extending from the portion of the rectification column corresponding to the upper layer of the liquid level of the stored liquefied carbon monoxide in the rectification column, Since the discharge path for discharging the hydrocarbon-based liquefied gas floating in the upper layer is provided outside the system, the liquid level of the stored liquefied carbon monoxide in the rectification column can be accurately controlled by the control means, and The hydrocarbon-based liquefied gas floating above the liquid surface of the stored liquefied carbon monoxide can be discharged from the discharge path to the outside of the system, and the product carbon monoxide having a higher purity can be taken out.

[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 cylinder, 6 ... Heat exchanger.

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 raw material gas supply path for guiding the raw material gas that has passed through the heat exchange means into the rectification column, and a rectification column for liquefying carbon monoxide in the raw material gas due to the difference in boiling point and separating the impure gas that is accumulated inside and discharged. A liquid nitrogen storage means for receiving and storing liquid nitrogen supplied from outside the apparatus; an introduction tower for guiding the liquid nitrogen in the liquid nitrogen storage means to the rectification tower as a cold source for liquefying carbon monoxide; By controlling the amount of liquefied carbon monoxide stored in the distillation column as it is or in the gaseous state as product carbon monoxide, and the amount of the stored liquefied carbon monoxide in the rectification column taken out to the above-mentioned outlet line. Liquid level of stored liquefied carbon monoxide Control means for constant control and hydrocarbons extending from the portion of the rectification column corresponding to the upper layer of the liquid surface of the stored liquefied carbon monoxide in the rectification passage and floating on the upper layer of the liquid surface of the stored liquefied carbon monoxide. An apparatus for separating and purifying carbon monoxide, comprising a discharge passage for discharging a system liquefied gas to the outside of the system.