JPH0774349B2 - Method for producing high calorie gas from LPG reformed gas - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing high-calorie city gas using liquefied petroleum gas (LPG) as a raw material.

[Conventional technology]

In order to reform LPG to obtain a quality suitable for city gas, steam reforming LPG has been conventionally used, and then CO conversion was performed with a copper-zinc catalyst to reduce the CO concentration (Japan Gas Association, "The 37th Urban Symposium Abstracts, P14-15,"
1989 ").

The outline of the flow sheet is shown in FIG. That is, LP
G enters the steam reforming tower 1 together with steam from the upper left of the drawing for reforming, and then CO shift is carried out in the first CO shift tower 2 in which a copper-zinc catalyst is filled with a zinc oxide catalyst as a desulfurizing agent. The off gas undergoes heat exchange in the heat exchanger 3. Therefore, lower the CO concentration to 5% or less and
G was added to the product gas. Table 1 shows an example of changes in gas composition and the like in this method.

[Problems to be Solved by the Invention] This method has a problem that it is difficult to enter the standard value of high-calorie gas such as 12A and 13A.

[Means for Solving the Problems]

The present invention provides a method for producing high-calorie gas that solves the above-mentioned problems.

That is, in the present invention, the reformed gas of liquefied petroleum gas is brought into contact with a catalyst containing iron oxide as a main component to remove sulfur compounds,
After the conversion, it is brought into contact with a nickel-alumina-based catalyst to react carbon monoxide and hydrogen in the gas to produce methane, and liquefied petroleum gas is added.
The present invention relates to a method for producing high-calorie gas that falls within the A or 13A standard.

The method of the present invention is applied to a gas obtained by cracking LPG by steam reforming or the like, or a gas obtained by further reforming it. For example, in the process of FIG.
The steam reformed gas at the position indicated by the mark is preferable.

The catalyst containing iron oxide as the main component is iron oxide (α-Fe
₂ O ₃ ) and zinc oxide (ZnO) and copper oxide (CuO) are supported,
A basic compound is added to this. Carrier is Ca
O, SiO ₂ , Al ₂ O ₃ , MgO, TiO _{2 and the} like are used alone or in a suitable mixture.

Iron oxide is mainly composed of α-Fe ₂ O ₃ , and ultrafine powder having a particle size of 60 μm or less is preferable. Such ultrafine iron oxide powder can be obtained by spraying a solution of iron powder dissolved in dilute hydrochloric acid or the like with fuel at 700 to 800 ° C. and roasting. ZnO and C
As uO, commercially available products can be used as they are.

The basic compound added to this is suitably an oxide or carbonate of an alkali metal or alkaline earth metal. Examples of oxides are CaO, MgO, etc., and examples of carbonates are NaHC
O _3, Na ₂ CO _3, may be mentioned CaCO _3, K ₂ CO ₃ and the like.

The composition of the catalyst is about 30 to 80% by weight of iron oxide, about 2 to 15% by weight of zinc oxide, about 2 to 15% by weight of copper oxide, and about 10 to 10% of carrier.
About 30% by weight, and about 1 to 10% by weight of the additive of the basic compound are suitable.

As a method for producing this catalyst, after iron oxide, zinc oxide and copper oxide are mixed, a carrier and an additive of a basic compound are added to water and mixed and granulated. Just bake. The carrier and basic compound may be added together with iron oxide or the like. A particle size of 5 to 20 mm is appropriate, 7
It is preferably about 15 mm.

This catalyst is capable of simultaneously decomposing organic sulfur, NOx and dienes at a relatively low pressure of 120 to 300 ° C and atmospheric pressure or higher. The flow velocity of the mixed gas is 100-1000hr ^{-1 in} space velocity (SV)
It can be used in a range of about 650 hr ^-1 , and very good removal results can be obtained at 650 hr ^-1 or less. In addition, the catalyst is regenerated by feeding a small amount of air and water vapor into sulfides such as Fe ₂ S ₃ and FeS which are regenerated into Fe ₂ O ₃ and can be continuously used for a long time.

LPG or its reformed gas is fed to the iron oxide catalyst tower at 100 to 20
The mixture is heated to about 0 ° C, preferably about 120 to 200 ° C and fed. Then, sulfur compounds and the like are removed in this tower, and then CO is converted. This off-gas is brought into contact with a nickel-alumina-based catalyst to react carbon monoxide and carbon dioxide in the mixed gas with hydrogen to generate methane.

Since this reaction raises the temperature by about 200 to 300 ° C, the heat is recovered by heat exchange or the like, and then the heat amount is adjusted to gasify the product. The amount of heat is adjusted by adding LPG.

[Action]

By reacting the iron oxide catalyst with the LPG reformed gas, H
₂ S, COS, CS ₂ , mercaptan, NOx, etc. are removed, and after the CO conversion, the nickel-alumina catalyst is reacted to react CO in the gas with H ₂ to change it to CH ₄ , and by adding LPG. We are preparing a gas that can be used as a high-calorie city gas.

〔Example〕

The apparatus shown in FIG. 1 was connected to the outlet of the steel reforming tower 1 of the conventional process shown in FIG. In this apparatus, a catalyst tower 4 filled with an iron oxide-based catalyst, a CO shift tower 5 and a catalyst tower 6 filled with a nickel-alumina-based catalyst are connected in series, and a heat exchanger is provided on the outlet side of each catalyst tower. 7 and 8 are connected. Then, LPG can be added at the outlet of the heat exchanger 8 for heat quantity adjustment, and then taken out as a product gas.

High-calorie gas was produced from LPG using such an apparatus. The composition of the steam reformed gas extracted from the process of FIG. 2 is as shown in Table 2.

The catalyst packed in the catalyst tower 4 was produced as follows. That is, in the steel industry, waste acid (FeCl ₂ 20 to 30%) generated when a steel sheet is pickled with hydrochloric acid is spray roasted at 700 to 800 ° C. to produce α-Fe ₂ O ₃ powder having a particle size of 60 μm or less. Obtained. To 50% by weight of this pickling dust, 5% by weight of ZnO and 5% by weight of CuO were added and mixed uniformly, and Portland cement (CaO 64%, SiO22
%, Al ₂ O ₃ 5%, etc.), sinter ore 23% by weight, and sodium bicarbonate 2% by weight, and water is added to the mixture to obtain a uniform mixture of 7 to 15%.
Granulated to a particle size of about mm.

A commercially available product was used as the nickel-alumina-based catalyst in the catalyst tower 6.

SV of catalyst tower 4 is 600 / hr, and SV of catalyst tower 6 is 5000 / hr
The gas temperature is around 200 ° C at the inlet of the catalyst tower 4 and 3 at the outlet.
The temperature was around 00 ° C, the catalyst tower 6 inlet was around 300 ° C, the outlet was around 500 ° C, and the heat exchanger 7 outlet was around 200 ° C. The pressure was 3 kg / cm ² and the amount of LPG mixed was changed in four stages.

The operation results are shown in Table 2.

Next, the results of obtaining the relationship between Cp and WI by adding LPG to the off gas of the catalyst tower 6 in various proportions are shown by the solid line in FIG. On the other hand, the relationship between Cp and WI when LPG is added to the reformed gas that has just been CO-transformed is shown by the dotted line in the figure.

〔The invention's effect〕

By the method of the present invention, a high-calorie gas that meets the standards such as 12A and 13A can be easily produced. In the manufacturing process, the life of each catalyst can be greatly extended, and since the sulfur content and the like are almost completely removed from the product gas, problems such as pipe corrosion do not occur at all.

[Brief description of drawings]

FIG. 1 is a flow sheet showing a modified portion used in an embodiment of the present invention in the process of producing high-calorie city gas from LPG, and FIG. 2 is a flow sheet of a conventional example. FIG. 3 is a graph showing the relationship between Cp and WI when the amount of LPG added was changed for the gas obtained in the example of the present invention and the gas of the comparative example.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazutsugu Kitajima 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. Chome 26-1 Fukuyama Gas Co., Ltd. (72) Inventor Hidenori Eguchi 2-26-1 Minatekicho, Fukuyama City, Hiroshima Prefecture Fukuyama Gas Co., Ltd. (56) Reference JP-A-60-264304 ( JP, A) JP 58-16324 (JP, A) JP 59-4183 (JP, B1)

Claims (1)

[Claims] 1. A reformed gas of liquefied petroleum gas is brought into contact with a catalyst containing iron oxide as a main component to remove sulfur compounds. After CO conversion, the reformed gas is brought into contact with a nickel-alumina-based catalyst to form carbon monoxide in the gas. 12A or 1 of city gas characterized by reacting hydrogen with hydrogen to generate methane and adding liquefied petroleum gas
Production method of high-calorie gas that meets the standard of 3A