JP2665783B2 - Method for producing 13A gas - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing 13A gas. 1
3A gas means that the WI (Wobbe index) specified in the Gas Business Act is 12600-13800 and the CP (burning rate) is 39.2-7.
It refers to those in the range of 0.0.

[Prior art] At present, those generally used as city gas are:
There are a variety of their properties, which cannot be burned with the same equipment or are very dangerous if at all. Typical of these gas types are LN
G (natural gas), LPG (commonly called propane),
There are gases obtained by steam reforming petroleum hydrocarbon feedstocks (LNG, LPG, naphtha, etc.).

These have completely different combustion speeds, calories, flame propagation speeds, etc., and cannot be burned with the same gas appliance as described above.

In recent years, many major city gas companies have been converting gas from conventional reformed gas (although there are also various types as described below) to LNG. This is due to the stable supply of raw materials, non-toxicity due to the absence of CO (carbon monoxide), suppression of gas stagnation due to low specific gravity, and increase in supply capacity due to high calories. is there.

The situation is exactly the same for small and medium-sized gas companies. That is, it is generally desirable to convert to 13A gas containing methane gas as a main component for the above various reasons.

However, since LNG has a very low boiling point, it must be stored at low temperature. Accepting LNG on its own (from abroad) and storing it in its own tank requires very large facilities. Impossible.

Therefore, it will receive supply from major gas companies and other companies that have LNG storage tanks, and supply it to general consumers.

In this case, it is needless to say that the conventional gas appliance must be converted to a 13A gas appliance.

[Problems to be Solved by the Invention] City gas is different from industrial fuel, etc.
Demand is not constant. That is, there is a large seasonal fluctuation. Comparing summer and winter, the demand in rough winter is 1.3 to 3.0 times that of summer, depending on the type of customer.

In such a situation, when the raw material gas is received from another company, the receiving company may not have the storage capacity enough to withstand the fluctuation. In particular, LNG
Most of them rely on imports and purchase them at low cost.
Often, they have contracts to constantly receive a certain amount throughout the year. Therefore, usually, the capacity of the storage tank is usually sufficient to withstand fluctuations in supply of the company.

In addition, even when supplying to other companies (here, small and medium-sized gas companies), it is conceivable that the overall capacity (storage and production) will increase, but the capacity increase will take into account the maximum fluctuation required by others. It is not possible to think about cost. Of course, those costs can be borne by small and medium-sized gas companies, but that is not actually possible.

For this reason, small and medium-sized gas companies will have a shortage of incoming LNG next to the peak, and will have to make up for that. However, as described above, LNG is not in-house, so this is not possible.

This is why conversion to 13A gas by small and medium-sized gas companies is delayed or impossible.

[Means for Solving the Problems] In view of the above situation, the present inventor has completed the treatment method of the present invention as a result of earnest research, and the feature thereof is that steam-reforming petroleum hydrocarbons. The point is that the production gas adjusted to the same calorie as the LNG to be mixed by mixing LPG with the reformed gas obtained by mixing LNG is mixed with 10 to 60% by volume LNG.

The present inventors have considered that small and medium-sized gas companies will produce 13A gas instead of other raw materials, for example, LPG, on the assumption that there is no LNG. It was too high to be possible. That is,
In 9500~11000Kcol / Nm ³ is a conventional LNG calories 13
A gas can not, we become about 13000~15000Kcal / Nm ^3. If the calories are different as described above, even if it is possible to burn with the same appliance, it cannot be carried out because of other disadvantages such as gas rate problems.

Therefore, the present inventors have focused on the fact that there is a wide range of properties that can be safely burned with a 13A appliance, and have recalled mixing other gases that are not themselves 13A. Although the calories are the same, mixing non-13A gas, of course, has resistance, but consider the mixing ratio,
If you keep it within the combustion range of 13A gas, you can burn safely.

Here, the petroleum hydrocarbon is obtained from petroleum, and LPG, naphtha, natural gas and the like are the main ones.

In steam reforming, hydrocarbons and steam are mixed to decompose hydrocarbons into hydrogen, carbon monoxide, carbon dioxide, and the like. Since this reforming reaction is an endothermic reaction, calorie must be provided from other sources, but the production method is different depending on the difference in this method.

In the low-pressure cyclic method, a reforming reaction is performed using heat obtained by a combustion reaction in a reaction furnace, and when the amount of heat is insufficient, a combustion reaction is performed again to generate heat. Therefore,
The combustion reaction and the reforming reaction are performed cyclically.

In the continuous partial combustion method, the amount of heat required for the reforming reaction is obtained by burning a part of the raw material.
Therefore, the reforming reaction and the combustion reaction occur simultaneously. For this reason, the production is performed continuously.

In the continuous partial combustion system, the reformed gas contains air. Since nitrogen gas in this air has a higher specific gravity than other components, for example, hydrogen gas or carbon monoxide gas, its gas specific gravity is higher than that of the above-mentioned cyclic type.

In the case of city gas, a large gas specific gravity is not desirable because it stays in lowlands and spreads slowly upward, especially in comparison with air.
Therefore, it is desirable to make the gas specific gravity as small as possible.

Therefore, it is conceivable to reduce the nitrogen component of the continuous partial combustion type combustion air as oxygen-enriched combustion air. That is, since it is only the oxygen in the air that supplies the calorific value by the combustion reaction, the idea is to reduce the nitrogen to reduce the specific gravity. Of course, it is difficult in terms of price and the like, but pure oxygen can be used.

The method of enriching oxygen in the air is not particularly limited, and includes a so-called PSA method in which the oxygen concentration is increased by utilizing a difference in adsorption rate due to a pressure difference, a method of using a commercially available oxygen-enriched film, and the like. .

Above all, the method using an oxygen-enriched membrane has simple equipment (about blower and oxygen-enriched membrane) and relatively high purity (25-40
%) Of oxygen is preferred.

The reformed gas referred to in the claims includes all the gases produced by the various methods as described above.

LPG refers to liquefied petroleum gas, a component of which is a mixture of propane and butane. However, only propane and butane alone are included here.

The reason for mixing LPG and air in the reformed gas is to first adjust the calories because the calories of the reformed gas are low, and to add a large amount of LPG and dilute it with air for the amount exceeding the predetermined calories . By doing so, the predetermined flammability is maintained and the gas production efficiency is improved.

The production gas referred to here is a gas that has been adjusted to the same calorie (calorific value) as LNG to be mixed by mixing LPG with the reformed gas. May be adjusted to the same calories as LNG.

LNG refers to so-called natural gas, which is mainly composed of methane, but its properties are not particularly limited.
For example, calories are not limited, and 9000-12000Kcal / Nm ³
It is sufficient if it is of the order.

The mixing ratio is 10 to 60%. Below 10%, LN
There is no point in compensating for the shortfall of G, and if it is 60% or more, 13A
This is because it is difficult to enter the range of flammability.

EXAMPLES Next, the present invention will be described in more detail based on examples. It is needless to say that LNG and other properties are merely examples, and the present invention is not limited to these.

 The composition and properties of LNG used in this example are as follows.

CH ₄ 88.5 C ₂ H ₆ 4.6 C ₃ H ₈ 5.4 nC ₄ H ₁₀ 1.5 Total 100.0 Calories: 11,000 Kcal / Nm ³ Specific gravity: 0.655 WI: 13599 CP: 41.34 Each component of the production gas by the method and the production gas using the air enriched with oxygen by the continuous partial combustion method is shown. The three production gases have already been adjusted in calories to the same as LNG by propane.

First, the mixing of LNG and production gas by the cyclic method will be described.

What is the maximum percentage of this production gas in LNG in the 13A combustion gas range?
Calculate whether you can mix up to. As the production gas is mixed with LNG, the WI becomes smaller and goes out of the range of 13A, so the limit of the mixing ratio is calculated from the limit of WI. Determining the mixing ratio is easy using specific gravity. Specific gravity and WI
Since the specific gravity is (calorie / WI) ² , (11,000 / 12,600) ² = 0.762 the mixed gas can be mixed up to the specific gravity of 0.762.

Since the specific gravity of LNG and the production gas by the cyclic method are 0.655 and 0.855, respectively, 0.762 = 0.855X + (1-X) x 0.655 X = 0.535 Therefore, the production gas of the cyclic method is 53.5% at the maximum.
Can be mixed.

The same calculation is performed for other production gases to obtain maximum mixing ratios of 28.3% and 31.2%, respectively. Table 2 shows the composition and properties of each of the maximum mixed gases. Shown in

FIG. 1 is a graph showing the combustion range of 13 A, in which the combustibility of LNG used in this example and the final mixed gas is plotted. Is the flammability point of LNG itself, and is the flammability when the production gas of the cyclic system, the production gas of the continuous partial combustion, and the production gas of the continuous partial combustion oxygen enrichment method are mixed to the maximum. Is a point.

Therefore, it can be seen that the mixture moves downward as the mixing ratio increases. The mixing ratio may be determined by selecting an appropriate part on this line.

For the production of the reformed gas, it is only necessary to use a device conventionally owned by each small and medium-sized gas company, and it is not necessary to introduce a special new device.

Mixing with LNG may be performed with a simple mixer. FIG. 2 shows a schematic flow sheet. Conventional gas production apparatus (here, plant of continuous partial combustion system) 1
The LPG2 is mixed with the reformed gas from the first mixer 3, heated to a predetermined calorie, and stored in the low-pressure water holder 4. The production gas of the holder 4 is supplied to the compressor 5
And is mixed with LNG 7 in the second mixer 6 and stored in the spherical holder 8.

In this example, all the components other than the second mixer 6 are existing devices.

Also, the flow is not limited to this example, and various other methods are conceivable.However, the point is that LPG is mixed with the reformed gas, which is the basis of the present invention, and then it is mixed with LNG to produce 13A gas. If are the same, it is needless to say that they are included in the present invention.

[Effect of the Invention] The 13A gas production method of the present invention has the following great advantages.

The company can cover the increased demand that the accepting company cannot handle.

To make up for the shortfall, companies that do not have their own LNG storage tanks will be able to convert to 13A gas. This is as small as possible for small and medium-sized gas companies from the perspective of preventing carbon monoxide poisoning and ensuring a stable supply.
This is consistent with the Ministry of International Trade and Industry's policy of wishing to convert to 13A gas.

The equipment is simple and almost conventional equipment can be used, so there is no extra cost. All that is required is to set up a receiving pipe with the recipient company.

It can be applied wherever there is any gas production equipment.

[Brief description of the drawings]

FIG. 1 is a graph showing the combustibility of each gas. FIG. 2 is a schematic flow sheet showing an example of the present invention. DESCRIPTION OF SYMBOLS 1 ... Conventional gas production apparatus 2 ... LPG 3 ... 1st mixer 4 ... Water holder 5 ... Compressor 6 ... 2nd mixer 7 ... LNG 8 ... Spherical holder

Claims (4)

(57) [Claims] 1. A production gas adjusted to the same calorie as LNG to be mixed by mixing LPG with a reformed gas obtained by steam reforming a petroleum hydrocarbon, and having a volume ratio of 10 to 60%. A method for producing 13A gas, which is mixed with LNG. 2. The method according to claim 1, wherein the reformed gas is produced by a low-pressure cyclic method. 3. The method for producing 13A gas according to claim 1, wherein the reformed gas is produced by a low pressure continuous partial combustion method. 4. The method for producing 13A gas according to claim 3, wherein the air used for the partial combustion is oxygen-enriched.