JPH0365216B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention connects a condenser that cools methane gas and refluxes liquefied methane to the top of a distillation column connected to a feed line for raw methane. A heater that heats and returns methane gas into the distillation column is connected to the lower part of the distillation column, and a recovery path for methane gas containing less heavy carbon methane is connected to the condenser;
The present invention relates to a heavy carbon methane separation device in which a recovery path for liquefied methane containing a large amount of heavy carbon methane is connected to the heater, and specifically relates to an improvement in a condenser.

[Conventional technology]

Previously, the cryogenic liquid nitrogen needed to condense methane gas was directly supplied to the condenser's cooling pipe.

[Problem that the invention seeks to solve]

However, a large amount of nitrogen gas is generated in the condenser, and since there is generally no customer that requires a large amount of nitrogen gas, the nitrogen gas from the condenser must be released, and the operation may be interrupted due to the consumption of liquid nitrogen. The drawback was that the costs were enormous.

An object of the present invention is to significantly reduce the cost required for cooling and condensing methane gas using a condenser.

[Means for solving problems]

The characteristic configuration of the present invention is that a condenser for condensing methane gas from a distillation column and refluxing liquefied methane is integrally molded with an evaporator of a compression heat pump that uses methane as a refrigerant, and a radiator of the heat pump It consists of a heat exchanger that cools a methane refrigerant with natural gas, and a compression means that compresses, cools, and compresses the methane refrigerant in that order is interposed between the evaporator and the radiator, and the methane refrigerant of the compression means The refrigerant cooling unit and the radiator are connected in such a way that liquefied natural gas is supplied to them in that order, and the effects are as follows.

[Effect]

An example of how the heavy carbon methane separator having this configuration is used will be described below. In use, the methane gas in the condenser is approximately 0.8 ata, -163°C. On the other hand, if a compression heat pump is operated using 10ata, -150℃ liquefied natural gas (LNG) as a cold heat source, and methane is used as the refrigerant, approximately 0.35ata, -173℃ liquefied methane will be transferred to the heat pump evaporator. The methane gas in the condenser can be sufficiently cooled and condensed by the heat pump's evaporator.

Here, the methane in the condenser condenses and that in the heat pump evaporates from wet saturated steam to dry saturated steam. That is, when the pressure state is the same, changes occur in opposite directions with the same boiling point as the boundary. The boiling point of methane at 1ata is −
Note that the temperature is 164°C, in this case, due to the need for heat exchange (the boiling point of the refrigerant in the heat pump needs to be lower than that in the distillation column), the pressure inside the heat pump is set to be low, and the boiling point is lower than that in the distillation column. is lowered.

In addition, the methane refrigerant from the evaporator of the heat pump is compressed by a compression means, then cooled, and then further compressed, or further cooled and compressed repeatedly, and supplied to the radiator, and used as a cold heat source. By supplying LNG to the radiator from the methane refrigerant cooling section of the compression means, the amount of power required for the heat pump can be sufficiently reduced.

By the way, if you process raw methane containing 1.1% heavy carbon methane at 21.8 x 10 ³ g/day and obtain a product containing 99% heavy carbon methane at 100 g/day, if only one compressor is installed. requires 115PS of power, but the first compressor, methane refrigerant cooling section and second
If a compressor is installed, the first compressor has 47PS, the second
The compressor requires only 48PS of power, a total of 95PS, which can significantly reduce the consumption of expensive electricity.

In addition, natural gas (NG) from radiators is in large demand as fuel, etc., and can be recovered and used as valuable materials without being released. Overall, this reduces power consumption and does not waste LNG. Cooling and condensation of methane gas in a condenser can be carried out with significant cost savings in terms of total cost.

〔Effect of the invention〕

As a result, methane consisting of carbon with an atomic weight of 13, that is, heavy carbon methane, which is useful as a tracer for isotope testing, can now be provided at a low price by significantly reducing manufacturing costs.

Furthermore, by using methane as a refrigerant in compression heat pumps, the following effects can be obtained.

(b) The boiling point inside the condenser and evaporator is adjusted based on pressure adjustment, but the refrigerant and the substance to be cooled (mainly heavy carbon methane)
Since they are almost the same substance, this adjustment is easy, and due to the characteristics of methane, the pressure of the refrigerant in the evaporator will be on the reduced pressure side.

(b) Furthermore, it becomes necessary to change the temperature of the evaporator due to changes in operating conditions. At this time, it is necessary to adjust the refrigerant pressure. Here, since this pressure adjustment is performed by changing the amount of refrigerant, even in this case, if the configuration of the present application is adopted,
It is possible to easily separately extract methane from the distillation column and supply it to the heat pump as a refrigerant.

〔Example〕

Next, an example will be shown with reference to FIG.

A feed line 2 of raw methane is connected to the distillation column 1, and a condenser 3 is connected to the upper part of the distillation column 1, which cools the methane gas containing less heavy carbon methane from the distillation column 1 and refluxes liquefied methane to the distillation column 1. , a recovery path 4 for methane gas containing less heavy carbon methane is connected to the condenser 3.

The first compressor 5a, the methane refrigerant cooling section 5b, and the second
A compression heat pump A is provided that circulates methane as a refrigerant in the order of a compression means 5 consisting of a compressor 5c, a radiator 6, a pressure reducing valve 7, and an evaporator 8, and the evaporator 8 is integrally molded with the condenser 3. Also,
The radiator 6 is connected to the methane refrigerant cooling section 5b through the LNG supply pipe 11, and is composed of a heat exchanger that cools the methane refrigerant with LNG.
A gas holder is installed to collect NG.

A heater 9 is connected to the lower part of the distillation column 1 by heating the liquefied methane rich in heavy carbons from the distillation column 1 and returning the methane gas to the distillation column 1, and a recovery path 10 for liquefied methane rich in heavy carbon methane is connected to the heater 9. It is connected to 9.
The heating tube 9a of the heater 9 is for vaporizing liquefied methane using a liquid carbon hydrogen-based heat transfer medium.

[Another example]

Next, another embodiment will be described.

As raw material methane and methane refrigerant, for example, those produced with high purity, those obtained by vaporizing LNG, or other suitable materials can be used.

The specific configuration of the distillation column 1 can be changed as appropriate, such as a multi-stage column type or a packed column type, and
A plurality or a large number of distillation columns 1 are connected in a multistage manner, that is, the recovery path 10 is connected to the subsequent distillation column 1 and the recovery path 4 is connected to the subsequent distillation column 1.
may be installed by being connected to the distillation column 1 in the preceding stage.

The models of the condenser 3 and heater 9 can be changed as appropriate.

The specific configuration of the compression heat pump A can be changed as appropriate. For example, to form the compression means, as shown in FIG. 2, one axial flow type compressor 5a is equipped with a methane refrigerant cooling section 5b whose peripheral wall is cooled with LNG to compress and cool the methane refrigerant. The compression means 5 may be configured to be repeated many times, and in short, the compression means 5 only needs to have the function of compressing the methane refrigerant, cooling, and compressing the methane refrigerant at least once in that order.

[Brief explanation of drawings]

FIG. 1 is a flow sheet showing an embodiment of the present invention;
FIG. 2 is a flow sheet showing another embodiment of the present invention. 1... Distillation column, 2... Raw material methane supply path, 3
...Condenser, 4...Methane gas recovery path,
5...Compression means, 5b...Methane refrigerant cooling unit, 6
... Heat radiator, 8 ... Evaporator, 9 ... Heater, 10
...Liquid methane recovery path, A...Compression heat pump.

Claims (1)

[Scope of Claims] 1. A condenser 3 for cooling methane gas and refluxing liquefied methane is connected to the upper part of a distillation column 1 connected to a supply line 2 of raw material methane, and the liquefied methane is heated and the methane gas is sent to the distillation column. A heater 9 is connected to the lower part of the distillation column 1, a recovery line 4 for methane gas containing less heavy carbon methane is connected to the condenser 3, and a recovery line 10 for liquefied methane containing more heavy carbon methane is connected to the heater 9. A heavy carbon methane separator connected to a heavy carbon methane separator, wherein the condenser 3 is integrally formed with an evaporator 8 of a compression heat pump A using methane as a refrigerant,
The heat radiator 6 of the heat pump A consists of a heat exchanger that cools the methane refrigerant with liquefied natural gas, and compresses, cools, and compresses the methane refrigerant in that order between the evaporator 8 and the radiator 6. Compression means 5
The methane refrigerant cooling section 5 of the compression means 5
A heavy carbon methane separation device in which the radiator 6 and the radiator 6 are connected in such a way that liquefied natural gas is supplied to the radiator 6 in that order.