JP2009243733A - Mixed gas composition fluctuation suppressing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mixed gas composition fluctuation suppressing device suitable as a supply device to combustion equipment requiring a high level of stability in a high generation amount such as a gas engine. <P>SOLUTION: When using fuel gas having fluctuation in the heating value, the fluctuating width needs to be suppressed to a degree in which a combustion device sensitive to fluctuation in the heating value can perform normal combustion. The invention focuses on a gas engine representing such a fuel device. According to "Advanced Technologies for Biomass Power Generation" (first publication July 31, 2006), in a heating value fluctuation limit of a gas engine, a heating value change rate is less than 1% in 30 seconds. Fig.4 is a graph showing the relation between an adsorption tower aspect ratio and a heating value fluctuation width in 30 seconds of fuel gas containing methane as the main component. When H/D≥0.5, superior combustion of the gas engine is maintained. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an apparatus for suppressing composition fluctuations of a mixed gas that requires stabilization of the composition, and in particular, suppresses composition fluctuations of the mixed gas suitable as a supply apparatus for a combustion apparatus that requires a high degree of heat generation stabilization such as a gas engine. Relates to the device.

In recent years, LNG (liquefied natural gas) satellite bases have been built with increasing demand for city gas in regions far from metropolitan areas. The LNG satellite base is a facility equipped with LNG storage tanks and vaporizers. After transporting LNG from the coastal LNG receiving base by lorry and storing it in the LNG storage tanks, the LNG is vaporized to industrial parks and residential areas. It is for supply as city gas.
In such an LNG satellite supply system, there is a case where the heat generation amount fluctuation of the supply gas accompanying the start of operation of the carburetor, load fluctuation, temperature change or the like becomes a problem. Various techniques have been disclosed. As an improvement of the vaporizer itself, a technique for purging LPG from a purge line when the LNG vaporizer is stopped has been proposed (for example, Patent Document 1).

In addition, as a calorific value adjusting device using an adsorbent, a technique has been proposed in which an adsorption tower filled with activated carbon is provided on the downstream side of the vaporizer to suppress fluctuations in the calorific value (for example, Patent Document 2). FIG. 5 shows a conventional satellite base 100 according to this method. The satellite base 100 mainly includes an LNG storage tank 101, a vaporizer 102 using outside air as a heat source, and an adsorption tower 103. The packed tower 103 is filled with activated carbon having a pore diameter of 2.0 to 3.0 nm. With such a configuration, the LNG supplied via the lorry 105 and the line 106 is temporarily stored in the LNG storage tank 101, vaporized by the vaporizer 102 to become natural gas, and further passed through the packed tower 103. Thus, when the composition ratio of the high boiling point (heavy hydrocarbon) component is high and the gas calorific value is high on the outlet side of the vaporizer, the high boiling point component is adsorbed by the adsorbent, and the composition ratio of methane which is the low boiling point component is When the gas heat generation amount is high and the gas heat generation amount is low, the adsorbed high boiling point component is desorbed to suppress the heat generation amount fluctuation.
JP-A-7-109476 JP 2005-273753 A

In the conventional calorific value adjustment method using an adsorbent, there is a limit to the amount of adsorbent adsorbed, so that the gas throughput per unit volume of the adsorption tower is limited. Therefore, when there is a combustion device (for example, a gas engine) that requires a high degree of heat generation stabilization on the downstream side, it is necessary to increase the adsorbent filling amount in order to suppress the heat generation amount fluctuation, There is a problem that the adsorption tower volume is increased and the construction work and the installation work are complicated. As described above, in the fuel gas supply apparatus including the LNG satellite base, there is a demand for downsizing the adsorption tower and improving the effect of suppressing the fluctuation in the heat generation amount of the fuel gas.
Furthermore, not only for fuel gas, but also for mixed gases such as raw material gas, by-product gas, exhaust gas, and produced gas from biomass in the chemical industry, the need to suppress composition fluctuations is increasing due to the demand for ensuring a stable supply. .

  As a result of diligent research, the inventors of the present application paid attention to the aspect ratio of the adsorption tower (tower height H / inner diameter D) (hereinafter sometimes abbreviated as H / D), and the adsorption ratio was set appropriately. It has been found that the composition variation can be suppressed within a desired range by using. Based on these findings, the present invention provides a composition fluctuation suppressing technique that makes it possible to suppress the composition fluctuation within a desired range with a smaller adsorption tower.

The gist of the present invention is as follows. That is, the composition fluctuation suppressing device for mixed gas according to the present invention is
(1) A composition fluctuation suppressing device that suppresses composition fluctuation by allowing a mixed gas whose composition fluctuates with time to pass through an adsorption tower, wherein the aspect ratio (column height / inner diameter) of the adsorption tower is It is characterized by being set to 5 or more.
In the present invention, “the gas composition varies with time” does not necessarily mean only a periodic variation, but also includes an aperiodic variation, and includes not only a continuous variation but also a single variation.
As the “adsorbent” packed in the adsorption tower, activated carbon, zeolite, silica gel, mesoporous silica, activated alumina, organometallic complex and the like can be used. Examples of the activated carbon include coal raw material activated carbon, coconut husk activated carbon, charcoal, petroleum raw material activated carbon, bamboo charcoal, phenol resin activated carbon, rayon-derived activated carbon, acrylonitrile-derived activated carbon, grass charcoal, sawdust charcoal, and peat.
(2) In the above invention, the aspect ratio is set to 0.67 or more.
(3) Each of the above inventions is characterized in that the mixed gas is a combustible gas and has a calorific value instead of the composition.
(4) The combustible gas is a fuel gas containing a hydrocarbon gas as a main component.
When using a fuel gas having a calorific value fluctuation, it is necessary to suppress the fluctuation range to such an extent that a combustion apparatus sensitive to the calorific value fluctuation can normally burn. In the present invention, attention is paid to a gas engine as a representative of such a fuel device. Regarding the limit of heat generation fluctuation of gas engines, according to “Latest Biomass Power Generation Technology” (supervised by Yoshikawa et al., CMC Publishing Co., Ltd., published on July 31, 2006), the calorific value change rate is less than 1% in 30 seconds. It is said.

FIG. 4 is a diagram showing the fluctuation range of the calorific value for 30 seconds when the aspect ratio of the adsorption tower is changed for the fuel gas containing methane as a main component. Although details of the test conditions and the like will be described later, it can be seen that when the aspect ratio is 0.5 or more, the rate of change in the calorific value is less than 1%, and good combustion of the gas engine is maintained. Furthermore, in the same figure, when the aspect ratio is less than 0.67, the calorific value fluctuation range greatly changes with a slight change in H / D. Therefore, in order to maintain stable combustion, it is more desirable to set the aspect ratio to 0.67 or more.
As for the upper limit of the aspect ratio, as described above, there is almost no change when H / D is 0.67 or more, and it can be said that there is no upper limit from the viewpoint of the calorific value fluctuation range. However, it is necessary to set a certain limit from the viewpoints of economy and seismic strength in manufacturing the adsorption tower. According to the revised 4th edition, Chemical Engineering Handbook (Chemical Engineering Association edition, Maruzen, published on October 25, 1978), the maximum height and diameter ratio of the adsorption tower is 5: 1 for the standard operating conditions of the adsorption tower. There is a description (page 882: Table 11.21). From these, it is considered appropriate that the upper limit is about H / D ≦ 5.

  In the present invention, “fuel gas” is a concept including a raw material gas, a by-product gas, a produced gas by biomass, and the like in the chemical industry.

(5) The above invention is characterized in that the fuel gas is natural gas or city gas mainly composed of methane.

Currently, city gas nationwide is classified into 13 types of gas groups based on the Wobbe index and burning rate index, and city gas companies can supply city gas of the specified gas type to consumers in the supply area. As required by the Gas Business Law. For example, 13A city gas mainly composed of methane is defined as 52.7 ≦ WI ≦ 57.8 and 35 ≦ MCP ≦ 47. Here, the Wobbe index (WI) is expressed by a numerical value (WI = Q / √s) obtained by dividing the calorific value Q (MJ / m3) of the gas by the square root of the specific gravity s of the gas with respect to the air of the gas. It is an indicator of In addition, the combustion rate index (MCP) is expressed as a function of the combustion rate of each combustible gas in the city gas (details are shown in the gas business law, and the description is omitted).
By using the gas within the range of the above 13A city gas as the fuel gas and passing through the calorific value fluctuation suppressing device according to the present invention, the device for the city gas 13A is burned well in the supply area. Can do.

  According to the present invention, even when the fuel gas accompanied by the calorific value fluctuation is supplied from the supplier, the fluctuation range is suppressed to the extent that the combustion apparatus sensitive to the calorific value fluctuation can be normally burned and supplied to the consumer. It becomes possible to do.

Hereinafter, embodiments of the present invention will be described in more detail with reference to FIGS. Needless to say, the scope of the present invention is described in the claims and is not limited to the following embodiments.
In this embodiment, an LNG vaporized gas whose composition varies at startup is used as a fuel gas, and the end-side load device is normally burned by passing through an adsorption tower set to an aspect ratio H / D = 1.0. Is.
FIG. 1 is a diagram illustrating an overall configuration of a fuel gas supply apparatus 1 according to the present embodiment. The fuel gas supply device 1 includes an LNG storage tank 4, an adsorption tower 2 provided in the path, and a gas engine 5 as a load device on the terminal side of the supply pipe L3. The LNG storage tank 4 stores LNG carried by a lorry (not shown). These devices are connected by supply pipes L1 to L3. The vaporizer 3 is supplied with LNG vaporized gas whose composition fluctuates (and the calorific value fluctuates with time). The adsorption tower 2 is filled with an adsorbent (for example, coal raw material activated carbon, coconut shell raw material activated carbon, etc.).
The fuel gas supply device 1 is configured as described above, and as a result, the LNG in the LNG storage tank 4 is vaporized by the vaporizer 3 to become natural gas, which is led to the adsorption tower 2 to allow the load device 5 to change the heat generation amount. After being controlled below the limit, the load is supplied to the load device 5 via the supply pipe L3.

FIG. 2 is a diagram comparing temporal transitions of fluctuations in heat generation at the outlet of the vaporizer 3 (FIG. 2A) and the outlet of the adsorption tower 2 (FIG. 2B) accompanying the activation of the vaporizer. Normally, a relatively high temperature (about −30 ° C.) gas remains in the vaporizer 3 before starting. When the start valve V1 is opened, the LNG in the LNG storage tank 4 flows into the lower manifold 3a of the carburetor 3 and vaporizes in contact with the pipe surface having the same temperature as the remaining relatively high temperature residual gas. In this case, among the hydrocarbons contained in LNG, the methane component having a low boiling point temperature (boiling point −161 ° C.) evaporates preferentially. The minimum heat generation amount Qmin) and the standard heat generation amount (Q0) with time. At this time, the gas near the minimum calorific value deviates from the good combustion region of the gas engine. However, since the hunting gas is guided to the adsorption tower 2, where the low calorific value component is adsorbed by the adsorbent and the ratio of the high calorific value component is increased, the calorific value at the outlet of the adsorption tower 2 is as shown in FIG. The fluctuation range is suppressed (minimum calorific value Q0 ′), and it falls within the good combustion region of the gas engine.
In this embodiment, the calorific value fluctuates at the time of start-up, supply amount change, LNG discharge pressure change, etc., but the gas is used in a normal state. However, the present invention is not limited to this. It is also possible to use a gas that varies.

Hereinafter, the content of the test conducted for confirming the effect of the present invention will be described.
(Test gas)
Flow LNG vapor (composition: CH4: 90.8%, C2H6: 5.0%, C3H8: 3.0%, i-C4H10: 0.6%, n-C4H10: 0.6%) for 2 minutes, then add to this gas for 1 minute By repeating the cycle of adding the gas (C3H8: C4H10 = 1: 1), a gas whose composition (calorific value) fluctuates periodically was prepared. The variation in calorific value of the test gas was a minimum of 44.3 MJ / m3 and a maximum of 46.8 MJ / m3.

(Test method)
As an adsorption tower, an adsorbent (coal raw material activated carbon) is placed in a test vessel (internal volume of 30 cc) having six aspect ratios (0.3, 0.5, 0.67, 1.0, 3.6, 36). ) The one filled with 12 cc was used. A test gas was allowed to flow into each test vessel under an inflow condition of a temperature of 25 ° C. and a superficial velocity of 2000 h ^{−1, and} a gas calorific value at the outlet of the vessel was measured with a calorimeter (product name: GasPT).

(Measurement result)
FIG. 3 shows the temporal transition of the calorific value fluctuation at each aspect ratio. In addition, in the same figure, the deviation from the average heat quantity after stabilization is plotted on the vertical axis so that the state of the heat generation fluctuation can be easily understood. Table 1 compares the maximum deviation of each aspect ratio. It means that the smaller the deviation from the average calorific value, the higher the calorific value fluctuation suppressing effect.

(Appropriate aspect ratio judgment)
FIG. 5 is a diagram in which the maximum value of the rate of change in calorific value for 30 seconds from 10 minutes to 50 minutes after the start of test gas inflow is plotted for each aspect ratio. From the figure, it can be seen that the rate of change in heat generation is almost constant when the aspect ratio is 0.67 or more. It can also be seen that when the aspect ratio is 0.5 or more, the rate of change allowed by the gas engine is less than 1% / 30 sec. An aspect ratio of 0.3 is smaller than the original heat generation fluctuation, but exceeds the allowable change rate, and is unsuitable for a gas engine. From the above results, it is determined that the lower limit of the aspect ratio is 0.5 or more, more preferably 0.67 or more.

  The present invention is not limited to the suppression of the calorific value of fuel gas, but also suppresses the fluctuation of the calorific value of fuel gas composed of a plurality of gas components whose calorific value fluctuates, such as raw material gas, by-product gas, exhaust gas, and produced gas from biomass Widely available.

It is a figure which shows the structure of the fuel gas supply apparatus 1 which concerns on one Embodiment of this invention. It is the figure which compared the time transition of the emitted-heat amount fluctuation | variation in the vaporizer 3 and adsorption tower 2 exit accompanying vaporizer starting. It is a figure which shows the time transition of the emitted-heat amount fluctuation | variation at the time of each aspect ratio in an Example. It is the figure which plotted the maximum value of the calorific value change rate for 30 seconds in 10 minutes-50 minutes after the start of test gas inflow about each aspect ratio. It is a figure which shows the structure of the conventional satellite base 100. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel gas supply device 2 ... Adsorption tower 3 ... Vaporizer 4 ... LNG storage tank 5 ... Load devices L1-L3 ... Supply line

Claims (5)

A composition fluctuation suppressing device that suppresses composition fluctuation by passing a mixed gas whose composition fluctuates over time through an adsorption tower filled with an adsorbent,
The aspect ratio (tower height / inner diameter) of the adsorption tower is set to 0.5 or more.
An apparatus for suppressing composition fluctuations in a mixed gas. In Claim 1, the aspect ratio is set to 0.67 or more,
An apparatus for suppressing composition fluctuations in a mixed gas. 3. The mixed gas composition fluctuation suppressing device according to claim 1, wherein the mixed gas is a combustible gas and has a calorific value instead of the composition. The composition fluctuation suppressing device for a mixed gas according to claim 3, wherein the combustible gas is a fuel gas containing a hydrocarbon gas as a main component. 5. The composition fluctuation suppressing device for mixed gas according to claim 4, wherein the fuel gas is natural gas or city gas mainly containing methane.

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