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EP-4357061-B1 - COMBUSTIBLE GAS

EP4357061B1EP 4357061 B1EP4357061 B1EP 4357061B1EP-4357061-B1

Inventors

  • UEHA, Hisato
  • KITA, Norihito
  • YOSHIDA, KAZUHIRO

Dates

Publication Date
20260506
Application Date
20230509

Claims (4)

  1. A combustible gas for use as a combustion gas for gas cutting of an object, the combustible gas comprising ethylene at a concentration of 1% by volume or more and less than 15% by volume, with a remainder being hydrogen and unavoidable impurities, wherein the combustible gas is encapsulated in a container, and a pressure in the container at 35 °C is 1 MPa or more and 50 MPa or less.
  2. The combustible gas according to claim 1, wherein a concentration of the unavoidable impurities is 1.0% by volume or less.
  3. The combustible gas according to claim 1 or 2, wherein the object is steel.
  4. Use of a combustible gas as a combustion gas for gas cutting of an object, the combustible gas comprising ethylene at a concentration of 1% by volume or more and less than 15% by volume, with a remainder being hydrogen and unavoidable impurities.

Description

[TECHNICAL FIELD] The present invention relates to a combustible gas. [BACKGROUND ART] A gas cutting method of cutting an object with a combustible gas is well known. In the gas cutting method, a mixed gas in which the combustible gas is mixed with an oxygen gas is burnt, thereby preheating the object with the resulting heat. Then, at a stage in which the object has been sufficiently preheated, an oxygen gas for cutting is further supplied, and the object is cut while being oxidized. As the combustible gas, Patent Document 1 proposed a combustible gas containing 38% by volume or more and 45% by volume or less of ethylene, with the remainder being hydrogen and unavoidable impurities (see Japanese Patent No. 4848060). This combustible gas can be easily stored, transported, etc. and enables contributing to an increase in quality of a finished state after gas cutting. Patent Document 2 proposed a combustible gas containing 18 % by volume or more to less than 40 % by volume of ethylene with the remainder being hydrogen. [PRIOR ART DOCUMENTS] [PATENT DOCUMENTS] Patent Document 1: Japanese Patent No. 4848060Patent Document 2: WO2014/002295 [SUMMARY OF THE INVENTION] [PROBLEMS TO BE SOLVED BY THE INVENTION] A hydrocarbon gas contained in the combustible gas serves as a calorie source, i.e., contributes to thermal power, and increases burning intensity. Thus, as shown in FIG 1, an ethylene concentration in the conventional combustible gas is set in the vicinity of a point at which the burning intensity shows a maximum. In this manner, a hydrocarbon gas concentration is typically set such that the burning intensity becomes high. Meanwhile, owing to current environmental problems, for example, SDGs (sustainable development goals) were adopted by United Nations in 2015, and phrases such as low CO2, decarbonization, carbon neutrality, etc. have been more and more highly publicized, raising a strong demand for a reduction of a CO2 gas. Also in the combustible gas, an amount of the hydrocarbon gas, which may serve as a CO2 source, is desirably as small as possible. However, as shown in FIG 1, the burning intensity is abruptly decreased when the ethylene concentration is lowered. The present invention was made in view of the foregoing circumstances, as a result of dedicated research and development aiming, as a company which provides combustible gases, to develop a combustible gas that enables lower CO2 emission, and an object of the invention is to provide a combustible gas that enables reducing an amount of CO2 generated at a time of cutting an object. [MEANS FOR SOLVING THE PROBLEMS] Conventionally, it has been considered that a decrease in the burning intensity leads to a decrease in a cutting rate and more time is required for cutting, thereby increasing CO2 gas emissions; however, as a result of intensive study of the reduction of the CO2 gas, the inventors of the present invention have found that, as shown in FIG 2, the decrease in the cutting rate is small in a combustible gas containing ethylene and hydrogen. In other words, when the ethylene concentration is reduced, the burning intensity decreases (FIG 1), but the decrease in the cutting rate is limited (FIG 2), and the increase in the cutting time is also limited. The inventors have discovered that, since a generation amount of the CO2 gas is determined by (hydrocarbon gas content in combustible gas × cutting time), with regard to the combustible gas, a reduction in ethylene concentration brings an effect of reducing the hydrocarbon gas content much more strongly than an influence of prolongation of the cutting time, enabling largely reducing the generation amount of the CO2 gas, and have completed the present invention. That is to say, an aspect of the present invention is a combustible gas for use as a combustion gas for gas cutting of an object, the combustible gas containing ethylene at a concentration of 1% by volume or more and less than 15% by volume, with the remainder being hydrogen and unavoidable impurities. In the combustible gas, a decrease in the cutting rate is small, while the concentration of ethylene, which is a hydrocarbon gas, is suppressed to be lower than an ethylene concentration at which the burning intensity is maximized; accordingly, the generation amount of the CO2 gas can be effectively reduced. Although the reason for the decrease in the cutting rate being small has not been identified, the inventors of the present invention have focused on the fact that the hydrogen concentration increases proportionally with a decrease in the ethylene concentration. As the hydrogen concentration increases, straightness of a flame increases and flow velocity becomes higher. It is surmised that the straightness of the flame and the high flow velocity compensate for the decrease in the burning intensity, thereby inhibiting the decrease in the cutting rate. The combustible gas is encapsulated in a container, and a pressure in the container at 35 °C is