JPS582203A - Catalytic decomposing method for natural gas - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing synthesis gas for methanol synthesis. Natural gas is used today as the primary feedstock for synthesis gas production.

According to the chemical formula of methanol CH30H, synthesis of methanol requires H2, CO and Co2. Synthesis gas has a suitable stoichiometric composition when the following conditions are met: CO+CO2 It is theoretically possible for the CO2 concentration to be zero, ie to CO2.

For example, in the case of hydrocarbons such as Natsuta, the H/C ratio is 2, but in the case of catalytic cracking of natural gas mainly containing a large proportion of CH4, gas analysis shows that there is too much H2 for synthesis. This unsuitable ratio can be eliminated, inter alia, by reducing the pressure of the bulk of the recycle gas from time to time from the methanol synthesis recycle. Only then, the circulating gas gradually becomes H
It is possible to be rich in Vacuum gas (gntspannungsgas) from the cycle of methanol synthesis can be used as fuel gas for catalytic cracking in a steam reforming furnace, as described in Canadian Patent No. 786,393 or in Chemical Economy φ Andor Engineering-v. B) -(Chemical Economy a)
ndEngineering Review) 1971
It is used as described in FIG. 2, September 2015, Vol. 3, No. 9 (No. 41), page 30. Maintaining the methanol synthesis operation in this way has the advantage that the gas production equipment is simple, but it has the disadvantage that too much hydrogen is produced, and this hydrogen is depressurized to almost atmospheric pressure in just one step. Since it has to pass through the entire equipment for this purpose, it cannot be burned in a reformer furnace as a fuel gas.

Chemical Economy and Engineering Review September 1971 Volume 3 No. 9 (No. 41) No. 21
Another known method, according to Page
The conversion device optimally adjusts the H/C ratio for methanol synthesis. In that case, a portion of the H2-rich and CO-containing crude gas obtained in one step of catalytic cracking is
At the stage of O-generator, CO□ and H are converted by CO-converter
2. In the next CO2-absorption step, H2 becomes CO
Separated from □, this H2 can be used elsewhere, while this CO2 is directed into the main gas stream to optimally adjust the H/C ratio.

In the known process, catalytic cracking produces too much hydrogen, i.e. ballast hydrogen.
is created. Furthermore, in the case of large installations, the design of the installation, which is expanded for this ballast hydrogen, reaches the limit of the industrial feasibility of the installation. Too much natural gas and energy is used for each unit of methanol.

Another possibility to improve the unfavorable H2/CO ratio in the catalytic cracking of CH4 consists in adding CO2 directly into the syngas stream. Petroleum and petrochemicals
eum & petrochemical), 1973
From August, Volume 13, No. 8, Page 74, Figure 2,
It is known to remove CO3 from cracker flue gas by chemical scrubbing, compressing it and adding it to synthesis gas. Obtaining CO3 from unpressurized smoke gas is expensive in terms of energy and investment.

The problem underlying the invention is to eliminate the drawbacks of the known methods.

This problem is solved according to the invention by combining the above-mentioned features in the manner described above.

An additional technical advantage of the process according to the invention lies in the optimal H/C dead power for methanol synthesis; already set in the catalytic cracker. So-called ballast hydrogen (Ba
This eliminates the need for more energy plates than are necessary to compress the ballast hydrogen, and the consumption of natural gas is significantly reduced.

Furthermore, all volume-related equipment is designed only for the actually required gas charge.

A number of examples according to the invention reproduce the following data: Amount of natural gas to be cracked: 181,285N
Analysis of m/h natural gas: CH498% N2 2% Pressure crab 51.8 bar Temperature: 92°C Volumetric flow rate at the inlet of the first reformer: 607.666N
m”/h analysis: CH29, 24% N O, 60% H2070, 16% Pressure crab 45 bar Temperature: 510°C Volumetric flow rate at the outlet of the first reformer: 730.726N
m3/h analysis: CO2,78% CO□6.51% H230,90% CH415,02% N20.50% H204,29% Pressure crab 42 bar Temperature near 20℃ Oxygen #67,539% m3/h Purity:
99.5% Pressure crab 41.5% Temperature: 150℃ Analysis: CO12,06% CO26,10% H243,48% CH40,85% N2 0.42% H2037,09% Pressure crab 40.5 bar Temperature: 1000 °C Results calculated from analysis of dry synthesis gas: Co
19.17% CO29,70% H269,11% CH41,35% N20.67% The ratio thereby obtained: co + co.

The value thus obtained is a calculated value that can be reduced to as low as 2.0 due to slight differences in the calculated values of raw materials, pressures and temperatures.

According to the invention, the known and expensive procedures for increasing the required H2/CO ratio can be discarded.

Claims (1)

[Claims] A method for producing synthesis gas for methanol synthesis by catalytically cracking natural gas at a pressure and high temperature above atmospheric pressure, comprising: a) decomposing the natural gas in two steps; b) a second step; C) the remaining decomposition in the second step is carried out at a pressure of 35-55 bar and a temperature of 650-800° C. until a residual concentration of CH of 13-20%; C) the remaining decomposition in the second step is carried out by adding oxygen; 900
A method characterized in that it is carried out by a known method at a temperature of from 1200°C to 1200°C.