JPS61107927A - Concentration of heavy carbon methane - Google Patents

Abstract

PURPOSE:To highly concentrate heavy carbon methane in methane gas through simple operation by increasing the proportion of heavy carbon methane with the help of a gas permeable membrane and condensing propane gas through cooling. CONSTITUTION:Methane gas and propane gas are interdiffused through a gas permeable membrane 4. Next, methane gas is supplied to the first separation tank 5 so that mainly propane is liquefied and separated. After this process, methane gas produced by concentrating heavy carbon methane is supplied as a feedstock to the (n+1) stage of concentration process from a flow passage 7. In addition, propane gas is supplied to the second separation tank 8 for liquefaction and separation. Methane gas produced through the concentration of light carbon methane is supplied as a feedstock to the (n-1) stage of concentration process from a flow passage 10. Further, liquefied propane from the first and second separation processes is supplied to an evaporation tank 11 for evaporation and the vapor is supplied to an interdiffusion process from a flow passage 3. Thus the same methane gas is subjected to a repeated cycle of the above concentration processes to obtain a required high concentration of heavy carbon methane in methane.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to methane containing 13 carbon atoms, that is, heavy carbon methane, at a high concentration, in order to be used as a tracer for isotope testing. Concerning a concentration method for obtaining methane gas.

[Prior art]

Conventionally, there was no concentration method as described above, and there were similar concentration methods as follows. In other words, by utilizing the boiling point difference between heavy carbon type carbon oxide, which consists of carbon with an atomic weight of 13, and heavy carbon type carbon oxide, which consists of carbon with an atomic weight of 12, heavy carbon type carbon oxide is concentrated by distillation. The process was repeated many times for the same carbon monoxide to obtain carbon monoxide containing a high concentration of heavy carbon-carbon oxides (no literature available).

[Problem that the invention seeks to solve]

However, the vapor pressure ratio of heavy carbon type carbon oxide and heavy carbon type carbon oxide is 0.993 at 81°IC, which is close to 1°, and the difference in boiling point is extremely small, making temperature control in the distillation process extremely difficult, making industrialization difficult. Furthermore, since -carbon oxide is highly toxic, there are drawbacks such as troublesome management to prevent leakage from equipment.

The purpose of the present invention is to simplify the concentration operation, eliminate the need to take too strict measures to prevent gas leakage, and, moreover, to economically advantageously obtain a gas containing multiple heavy carbons. be.

[Means to solve the problem]

The characteristic means of the present invention includes a step of interdiffusing methane gas and propane produced from liquefied natural gas through a gas-permeable membrane, in which heavy carbon methane gas permeates more preferentially than heavy carbon methane gas, and the step of interdiffusion. The concentration step consisting of the first separation step of cooling the methane gas with liquefied natural gas and separating liquefied propane from the methane gas is repeated many times for the same methane gas, and in each concentration step, the mutual diffusion is a second separation step in which the propane gas from the step is cooled with liquefied natural gas to separate the liquefied propane from the methane gas; and a second separation step in which the liquefied propane from the first and second separation steps is heated with water and vaporized. Te, PuC7
A propane recovery and utilization step is performed to supply the methane gas to the mutual diffusion step, and the methane gas from the second separation step is transferred to the first stage of the concentration step. The purpose is to perform a methane recovery and utilization process to be supplied to the above-mentioned interdiffusion process, and its effects are as follows.

[Effect]

In other words, after increasing the ratio of methane to heavy carbon methane in the gas through a gas permeable membrane, the propane gas in the methane gas is cooled and condensed to reduce the concentration of heavy carbon methane in the methane gas. On the other hand, the difference between the condensation temperatures of methane and propane is extremely large at 119.4 d@g, and therefore, during concentration, it is only necessary to control the temperature in the first separation step quite roughly. Also,
For the same reason, it is only necessary to perform very rough temperature control in the second separation step, and in the propane recovery and utilization step, it is sufficient to heat the liquefied propane to a temperature higher than its vaporization temperature, and the temperature control can also be done very roughly. , Overall, heavy carbon methane can be concentrated with simple operations.

In addition, since methane and propane are extremely weakly toxic, there is no need to take strict precautions against gas leaks from equipment when dealing with carbon monoxide, and it is easy to manage gas leaks. It's safe.

The methane gas with a low concentration of heavy carbon methane that comes out of the second separation process for the first concentration process can be used as is as fuel, etc., so there is no need for any special equipment for exhaust gas treatment. .

Furthermore, since methane as a raw material and propane as a contact medium are obtained from liquefied natural gas, and the cold heat of liquefied natural gas is used as an energy source in the first and second separation steps, overall liquefied natural gas is less expensive. It can be used very rationally, and since the process of recovering and using propane only requires heat from seawater, river water, etc., overall,
The f14 cost of valuable energy such as electricity and oil becomes extremely small, and operating costs can be kept sufficiently low.

〔Effect of the invention〕

As a result, methane gas, which is useful as a heavy carbon source, can be obtained with advantages in terms of production management, equipment, and cost, making it possible to carry out the process on an industrial scale.

〔Example〕

Next, examples will be shown.

First, the n-th stage of the concentration process will be explained with reference to FIG.

The methane gas from the first separation tank on the (n-1) stage and the second separation tank on the (n + 1) stage is transferred from the flow path (11) to the diffusion tank (
Propane gas is supplied to the first compartment (2a) in the diffusion tank (2), and the propane gas to be used in the future is supplied from the channel (3) to the second compartment (2b) in the diffusion tank (2). Methane gas and propane gas are allowed to interdiffuse through a gas permeable membrane (4) through which the gas permeates more preferentially than heavy carbon methane gas, and the methane gas from the interdiffusion process is supplied to the first separation tank (5) and piped. Cooling with liquefied natural gas in path (6), mainly liquefies propane and separates it from methane gas, and its glI1
1. Heavy carbon methane from separation process? The resulting methane gas is supplied from the flow path (7) to the (n+1)th stage concentration step as a raw material.

Note that methane gas and propane gas are produced by distilling liquefied natural gas.

The propane gas from the interdiffusion process is transferred to the second separation tank (8).
The methane gas concentrated in heavy carbon methane from the second separation step is supplied to the flow path (10) and cooled by the liquefied natural gas in the pipe (9) to liquefy and separate mainly propane from the methane gas. ) to the (n-1)th stage concentration step, a methane recovery and utilization step is performed to supply it as a raw material.

The liquefied particles from the first and second separation steps are supplied to an evaporation tank (B) and heated and vaporized with water such as seawater or river water in the pipe (2) to produce propane gas. A propane recovery and utilization step is performed to supply the interdiffusion step from the channel (3).

In addition, in the first stage concentration step, the methane gas from the second separation step is recovered from the flow path (l(g)) to the fuel supply equipment.

The above-mentioned concentration step is repeated many times for the same methane gas, and the concentration of heavy carbon methane in the methane is made to a desired high concentration, for example, 5 Oqk or more, and the high concentration heavy carbon methane is An example of the equipment is shown below using $2FQ to Figure 4.

A diffusion tank (2), a second separation tank (8) below it, and an evaporation tank (B) are formed integrally and partitioned by a partition (to),
A first compartment (2a) and a second compartment (2b) below it are formed in the diffusion tank (2) by the gas permeable membrane (4), and the second compartment (2b) is connected to the second separation tank (2). 8), a flow path α→ for supplying propane gas, and a flow path for supplying all K propane gas from the evaporator tank (B) to the second compartment (2b) (a circulation fan (15m), (15b) is connected to Kl). A large number (TL) or Tm of integrally formed tanks as described above are provided.
) are arranged horizontally in parallel.

A first separation tank (6) is arranged above each of the tanks (T, ) or Tm), and the first compartment (2a) and the first separation tank (
5) with a pipe (to), and the methane gas is connected to the first pipe on the upstream side.
It is configured so that it is sequentially supplied from the separation tank (5) to the first compartment (2a) on the downstream side.

The first separation chamber 1 (51) on the upstream side and the first compartment chamber (2
a) is connected with a pipe for forming a flow path (7), and methane gas is supplied as a raw material to the vJ1 compartment (2a) on the downstream side.

Pipe line (with pump fP) that supplies liquefied propane in the second separation tank (8) to the spray nozzle (17a) in the evaporation tank (B)
) is installed, and the liquefied propane in the first separation tank (5) is transferred to the spray nozzle in the evaporation tank (b). A gravity flow pipe line (6) is provided to supply the fuel to the fuel tank 17b), and the evaporator tank (b) is configured to generate propane gas.

The liquefied natural gas is supplied to all of the first separation tank (5) and passes through the liquefied natural gas supply pipe (9), and the water supply pipe @ passes through to all of the evaporation tank (b). It is.

The methane gas pipe (barrel) connected to the second separation tank (8) K on the most upstream side and the pipe for forming the flow path (7) connected to the first separation tank (6) on the most downstream side are collected separately. Gas holder (20
a) and (20b).

[Other actual flow side]

Next, another example will be described.

As the gas permeable membrane (4), any membrane can be used as long as it allows heavy carbon methane to permeate preferentially over heavy carbon methane.

The number of times the concentration step is repeated may be appropriately selected depending on the concentration performance of the gas permeable membrane (4) and the desired concentration of heavy carbon methane, and can be selected within a wide range from a relatively small number of times to an extremely large number of times. .

The specific configuration of the equipment used and the purpose of the recovered methane gas do not matter.

FIG. 1 is a flow sheet illustrating the method of the present invention.

2 to 4 illustrate the equipment used in the method of the present invention, FIG. 2 is a schematic vertical sectional view, and FIG.
4 is a view taken along the ff-IF arrow in FIG. 2.

(4) ... is a suction permeable membrane.

Claims (1)

[Claims] A step in which methane gas and propane gas produced from liquefied natural gas are interdiffused through a gas permeable membrane (4) through which light carbon methane gas permeates more preferentially than heavy carbon methane gas, and the methane gas from the interdiffusion step is transferred to liquefied natural gas. A concentration step consisting of a first separation step of separating liquefied propane from methane gas by cooling with gas is repeated many times for the same methane gas, and in each concentration step, the propane gas from the interdiffusion step is liquefied. a second separation step in which liquefied propane is separated from methane gas by cooling with natural gas; and a second separation step in which liquefied propane from the first and second separation steps is heated with water to vaporize it, and the propane gas is separated from the interdiffusion step. We conduct a propane recovery and utilization process to supply
and a heavy carbon methane concentration method in which, in the second and subsequent stages of the concentration step, a methane recovery and utilization step is performed in which methane gas from the second separation step is supplied to the interdiffusion step in the previous stage of the concentration step.