JPH036294A - Production of 13a gas as lng substitute - Google Patents

Abstract

PURPOSE:To obtain a substitute for natural gas and to improve gasification efficiency, etc., by mixing a reformate gas obtained by the steam reformation of a petroleum hydrocarbon with propane and air and specifying the combustion range and specific gravity of the gas. CONSTITUTION:A reformate gas is prepared by the steam reformation of a petroleum hydrocarbon such as LPG or naphtha by the low-pressure cyclic process, intermediate to high pressure continuous external heating process, continuous partial combustion process, etc. The formed gas is mixed with propane and air to produce the subject gas which satisfies the requirement of the combustion range as 13A gas, i.e., WI of 12,600-13,800 and CP of 39.2-70.0, and has a specific gravity of 1 or less.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Utilization] The present invention relates to a method for producing LNG substitute 13A gas. 13A gas is defined in the Gas Business Law and has a Wl (Wotsube Index) of 12,800 to 13.
800 with a CP (burning rate) in the range of 39.2 to 70.0. Wl and CP are determined by the following formulas.

Here, Hs C0% CmHnSCH4 is the concentration (volume %) of hydrogen gas, -carbon oxide gas, hydrocarbon gas other than methane gas, and methane gas, respectively. K is a coefficient determined by the oxygen concentration, and in the case of zero oxygen, it is 0.99.
In the case of 5%, it is set as 1.14.

[Prior Art] The concept of city gas does not refer to one type of gas, but refers to gas used by ordinary households, and has various properties. Typical types of these gases include LNG (natural gas), LPG (commonly referred to as propane), and petroleum-based hydrocarbon feedstock (LNG).
, LPG, naphtha, etc.) obtained by steam reforming.

In order to properly burn gas, it is necessary to use an appliance that matches the combustion rate and calories. Using an appliance that does not match the combustion rate and calories will cause incomplete combustion, flame lift, etc.
Phenomena such as extinguishing of flame due to backfire occur.

This flammability range for the various gases mentioned above is very different, and there is no appliance that can properly combust them all. Therefore, this flammability is very important for gas supply companies.

Recently, many major city gas companies are converting their gas from conventional reformed gas (there are various types as described below) to LNG (13A gas), but most Small and medium-sized city gas companies produce and supply the above-mentioned reformed gas type gas because they are unable to make a profit due to the enormous cost of capital investment.

Since the reformed gas itself has a low calorie and has a low gasification efficiency (total supplied gas calorie/total raw material calorie), the amount of heat is adjusted by LPG and air. This uses LPG to increase the calorie content of the reformed gas above the calorie value to be supplied, and then dilutes it with air to a predetermined calorie level. In this way, the LPG during thermal N adjustment is simply vaporized using waste heat, so the gasification efficiency is approximately 100%. Therefore, ■
- Tar gasification efficiency will increase.

However, companies that manufacture such reformed gases have various problems as described below.

[Problem to be solved by the invention] The above problems will be explained.

fl) With the increase in the number of consumers, the capacity of supply pipes is becoming insufficient, and it is becoming necessary to increase the size of main pipes.

(2) As mentioned above, since raw materials are reformed in reformed gases, the gasification efficiency is naturally lower than that of LPG or LNG.

(3) Recently, as major gas companies have switched to natural gas, most of the newly developed gas appliances are for 13A, which is in high demand, and there are concerns that conventional 50.60 etc. specification appliances will not be developed. be.

(4) In addition, the conversion to natural gas will ensure a stable supply of raw materials, non-toxicity as it does not contain CO (-carbon oxide), gas diffusivity due to its low specific gravity, and increased supply capacity due to its high calorific value. This is strongly recommended by the Ministry of International Trade and Industry.

Therefore, even small and medium-sized gas utilities will have to switch to natural gas eventually. In such a case, the longer the conversion is delayed, the more the number of consumers will increase, and the more it will cost to convert gas appliances to natural gas.

Of course, it would be good if we could switch to natural gas right now, but LN
Many gas utilities have not implemented this because the cost of equipment such as gas storage tanks is enormous and unprofitable.

As a way to overcome these drawbacks, all steam reforming is stopped and the feed gas is a mixture of propane and air, which has a much higher calorie content than the conventional one (15,
0OOKcal/Nm3) and put it in the 13A combustion range.

This method has high calories, no problems with combustion range, uses the same equipment as major gas companies, and has extremely high gasification efficiency. Although it seems that all of the above-mentioned drawbacks have been solved, this gas has the fatal drawback of having a specific gravity of 1 (assuming air is 1) or more.

Due to its inherent nature, combustion gas has the risk of explosion, and of course, if a large amount remains indoors, there is also the risk of oxygen deficiency. That is, it is desirable for the leaked gas to quickly rise and diffuse, and it is extremely dangerous for the gas to remain near the ground surface. Furthermore, even if the leakage occurs in an underground conduit, the leakage does not reach the surface and spread, but remains underground, causing a major accident.

Therefore, gas utilities that have traditionally supplied reformed gas have a strong desire to maintain a gas specific gravity of 1 or less even when converting to an LNG alternative gas system. be.

[Means for solving the problem] In view of the above-mentioned current situation, the present inventor has completed the treatment method of the present invention as a result of intensive research. Propane and air are mixed into the reformed gas obtained by doing this, and the combustion range of the gas after mixing with vi is within the range of 13A, and its specific gravity is 1 or less.

Here, petroleum-based hydrocarbons refer to hydrocarbons separated or produced from petroleum, and representative examples thereof include LPG (mainly containing liquefied petroleum gas, propane, or butane), naphtha, and the like.

Steam reforming refers to a reaction in which raw material hydrocarbons are decomposed by steam to produce hydrogen, carbon oxide, carbon dioxide, and the like. Since this steam reforming reaction is an endothermic reaction, it is necessary to provide heat in order to continue the reaction. Depending on the method of applying this heat, there are cyclic methods, external heat continuous methods, continuous partial combustion methods, etc.

In the cyclic method, before raw materials are introduced into the reactor, fuel is introduced into the furnace and burned to raise the temperature inside the furnace, allowing the furnace to retain a certain amount of heat, and then raw materials and steam are introduced to reform the reactor. When a fuel reaction occurs and the temperature inside the furnace drops below a certain level, the fuel is combusted again to raise the temperature. Therefore, the feature is that gas production is performed cyclically. The external heat continuous method is a method in which the amount of heat necessary for the reforming reaction is continuously applied from outside the reactor (often in the form of a tube or vibrator). In this method, since the reactor is of a tube type or the like, the reaction is often carried out at medium or high pressure. The continuous partial combustion method is one in which the amount of heat required for steam reforming is obtained by burning part of the raw material. That is, it is manufactured by mixing air with the raw material and steam and partially combusting it.

The reformed gas referred to in the claims includes all gases produced by the various methods described above,
Gas used for completely different purposes is not included, and the calorie of the gas produced from the reactor is 4000 cal/Nm3.
It is as follows. In addition, the medium pressure referred to in this specification refers to IKg/cm2G or more as defined by the Gas Business Act and 10Kg/cm2G or more.
The concept refers to less than m2G, below this is called low pressure, and above this is called high pressure, and also includes gas obtained by converting gas from the reactor to CO. CO transformation is a reaction represented by CO+H2O-CO2+) (2), which transforms toxic carbon monoxide into carbon dioxide and hydrogen using water vapor.The transformation rate of CO and the rate of passage through the transformer are also There is no particular limitation, and the usual one may be used.

Furthermore, when the specific gravity of the reformed gas is high, carbon dioxide in the reformed gas may be removed. That is, this is a method of washing with an amine solution or a potassium carbonate solution.

This is because removing carbon dioxide, which has a high specific gravity, lowers the specific gravity of the reformed gas.

Furthermore, in the continuous partial combustion method, in order to further lower the specific gravity of the reformed gas and to lower the concentration of nitrogen gas in the introduced air, it is also conceivable to use oxygen-enriched air. As a method, it is convenient to use a commercially available oxygen enrichment membrane.

Propane as used herein means that the main component is propane gas, and does not refer only to pure propane. For example, propane or industrial propane may be used. Further, the mixed amount of air may be almost O depending on the amount of propane.

The above concept is completely different from the conventional simple adjustment of heat amount. That is, the currently implemented caloric joint described above is merely aimed at improving gasification efficiency.

However, the method of the present invention uses reformed gas, propane, and air to produce gas that falls within the 13A flammability range (13A gas).
The purpose is to produce a product having a specific gravity of 1 or less. In other words, the goal is to significantly change the combustibility of conventional gas and make it the same as that of natural gas.

The flammability is not determined based on the properties of the gas being produced, but rather the flammability is changed to match the flammability of the gas planned to be adopted in the future, and flammability conversion in this sense has not been done at all in the past. .

Next is the mixture ratio of reformed gas, propane, and air.
This varies depending on the composition of the reformed gas, but any ratio may be used as long as it falls within the 13A combustion range and the specific gravity is 1 or less. Of course, it goes without saying that there are limits.

13A combustion range, wr is 12600-1380
0, CP is 39.2 to 70.0, and specific gravity <1.0
Consider the range that satisfies the following.

For example, if the calorie is fixed, only propane is mixed with the reformed gas to produce gas adjusted to the calorie. Of course, in this case, the air is 0. If propane and air are appropriately increased beyond this, the specific gravity will increase, and as is clear from the above-mentioned calculation formulas for wi and CP,
Wl and cp become smaller. Therefore, if the specific gravity is 1 or more or Wl or CP is below the lower limit at the time of air ○, the gas cannot be adjusted to the 13A gas of the present invention.

Therefore, at the time of air 〇, the specific gravity is 1 or less, Wl and CP
is assumed to be lower ■ or higher.

Then, propane is further mixed with this gas, and the calorie content is adjusted with air. The mixing limit of propane (that is, the mixing limit of air) is the specific gravity of 1.
or until Wl or CP reaches the lower limit.

This is actually a very limited range, and the amount of air mixed is often about 0 to several percent.

Also, if the calorie to be set is increased, the change depending on the amount of propane mixed will be the same as above, but WISCP will become thicker according to the calorie, so this is an advantage, but the specific gravity will increase, so it will not actually work. In this case, the air mixing range does not change much.

Therefore, depending on the type of reformed gas, increasing the set calorie means that if there is a problem with the specific gravity, the amount of propane that can be mixed will decrease, and if there is a problem with Wl or CP,
This means that the amount of mixture will increase.

[Example] Next, the mixing ratio of each component will be explained based on an example.

First, the cyclic reformed gas is used as the reformed gas.
Select O-transformed gas and CO-transformed gas from continuous external heat reformed gas. Then, 12,500 and 13,500Kc61/Nm3 are selected as the final gas calories.

Table-1 shows the components of the above two types of reformed gas and the components of propane and air to be mixed. -2 is produced gas by medium pressure continuous external heating method.
It is an O-transformed gas. Each component described here is a normal value and is based on a currently practiced manufacturing method.

P-1 is the composition of propane, and A-1 is the composition of air. Of course, this is not a strict thing, but a matter of convenience. Moreover, the efficiency in the table is the gasification efficiency described above. still,%
is volume %.

Table 2 shows an example in which the final calorie is 12,500 Kcal/Nm3 using cyclic reformed gas as one component; G-1 has the calorie adjusted only with propane; G-3... each has an increased amount of propane. Of course, in order to match the calories, the amount of air mixed will increase accordingly. In this Table-2, G-1 and Table 1 have a specific gravity of 1 or less and fall within the range of 13A. There are only 2. Of course, this does not mean that the mixing ratio is 2 points.

Next, using the same reformed gas, 13,500Kcal
/Nm3 is shown in Table 3. In this case, the WI increases as a whole, and there is some margin up to the lower limit, but the specific gravity becomes a problem. In this example, only G-6 is within the 13A range.

Tables 4 and 5 show that the reformed gas of medium pressure continuous external heating method is
Calories were adjusted in the same way as above using O-transformed gas (S-2), and Table 4 shows 12,500 Kc.
al/Nm3, Table-5 is 13,500 Kcal/Nm
3.

Similar to the above, those having a specific gravity of 1 or less and falling within the flammability range of 13A are G-12 and G-16, respectively.

FIG. 1 is a schematic flow sheet for carrying out the manufacturing method of the present invention. The reformer 1 may be a normal one, and the propane and air mixer 2.3 may be a normal one for adjusting the amount of heat.

Therefore, in reality, any gas company that has the reformer 1 can implement it without requiring any special equipment.

In this case, as a method for introducing propane into the mixer 2, the liquid may be introduced by an injection method, or a paper riser may be provided separately and the propane may be introduced after being vaporized.

Figure 2 shows the flammability of the gases in Tables 2 and 3 above.
This is shown on a graph along with the flammability range of 3A. This graph shows calories of 12.500 and 13.50.
13.000.14,000.15.000K other than 0
Cal/Nll3 is also shown.

All dotted line portions have a specific gravity of 1 or more and are not included in the gas of the present invention.

From this, it can be clearly seen that as the amount of propane mixed increases, the graph moves toward the lower left and deviates from the range of 13A.

After all, the range of the gas of the present invention is on the solid line and within the range of 13A.

FIG. 3 similarly shows the combustibility of the gases shown in Tables 4 and 5, and the rest is the same as FIG. 2.

[Effects of the Invention] The method for producing LNG substitute 13A gas of the present invention has the following great advantages.

■ 13A gas can be produced.

This is in line with the policy of conversion to LNG recommended by the Ministry of International Trade and Industry.

■ Existing equipment can be used as is, so it can be implemented with only minor changes.

■ Since 13A gas equipment can be used, equipment developed by major gas companies can be adopted.

■ Of course, it is necessary to convert the equipment now, but the cost is lower compared to conversion after the number of customers increases in the future.
Construction such as conversion is also easy.

■ Since the amount of propane mixed in is very large, the gasification efficiency is improved compared to the gas production method before conversion.

■ Since the calorie content is higher than before, there is more room in the conduit.

[Brief explanation of drawings]

FIG. 1 is a schematic flow sheet showing one example of the present invention;
Figures 3 and 3 are graphs showing flammability. Patent applicant Kyushu Gas ■ Figure 2 Figure 1 Series 3 0 1J

Claims (4)

[Claims] 1. Propane and air are mixed into the reformed gas obtained by steam reforming petroleum hydrocarbons, and the combustion range of the gas after mixing is within the range of 13A, and the specific gravity is 1 or less. A method for producing 13A gas as an LNG substitute. 2. The method for producing LNG substitute 13A gas according to claim 1, wherein the reformed gas is produced by a low-pressure cyclic method. 3. The method for producing LNG substitute 13A gas according to claim 1, wherein the reformed gas is produced by a medium-high pressure continuous external heating method. 4. The method for producing LNG substitute 13A gas according to claim 1, wherein the reformed gas is produced by a continuous partial combustion method.