JP2008231357A - Mixed gas feeder, calorific value adjustment apparatus, and its variation adjustment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mixed gas feeder suitable for stabilization of a calorific value of a fuel gas such as town gas, and its composition variation adjustment method. <P>SOLUTION: In the initial setting stage, a switching valve Va is set to the opened state and a switching valve Vb is set in the closed state. A composition ratio of the fuel gas and an environment temperature at a periphery of a packed column are measured. Calorific value variation width ΔHa, ΔHb after passing through the packed column is operated based on these measurement value and a determination table, and ΔHa is further compared with ΔHb. When ΔHa is smaller than ΔHb, the switching valve Va is made opened and it passes through the packed column 2a. At the time of ΔHa>ΔHb, Vb is set in the opened state and Va is set in the closed state. The mixed gas is set so as to pass through the packed column 2b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a mixed gas supply device, a calorific value adjustment device, and a variation adjustment method thereof, and more particularly to a mixed gas supply device, a calorific value adjustment device, and the like suitable for stabilizing the calorific value of fuel gas such as city gas.

  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 terminal by lorry and storing it in the LNG storage tank, 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 adjustment device using an adsorbent, a technique for suppressing the calorific value by providing an adsorbent packed tower filled with activated carbon on the downstream side of the vaporizer has been proposed (for example, Patent Document 2). FIG. 7 shows a conventional calorific value adjusting device 100 using such an adsorbent packed tower. A conventional calorific value adjusting device 100 mainly includes an LNG storage tank 101, a vaporizer 102 using outside air as a heat source, and an adsorbent packed tower 103. The adsorbent 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 tank 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 adsorbent 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 calorific value is high and the gas calorific value is low, the adsorbed high boiling point component is desorbed to suppress the calorific value.

JP-A-7-109476 JP 2005-273753 A

In general, it is known that the amount of adsorbent adsorbed decreases at a high temperature and increases at a low temperature. However, with regard to the calorific value fluctuation adjusting method using an adsorbent, Patent Document 2 discloses a technique for stably supplying natural gas by heating the packed tower to a set temperature (35 ° C.) in winter. However, there is no disclosure of a calorific value adjustment method over the environmental temperature range assumed in practice. The same applies to the composition variation suppressing technique.
In addition to temperature, the amount of adsorbent adsorbed generally varies depending on the type of gas to be adsorbed. For example, propane and butane adsorb more butane having a high boiling point. However, regarding the calorific value adjustment method using the adsorbent, the fluctuation of the calorific value is caused by an increase in propane and butane (Patent Document 2), but a specific composition ratio at the time of fluctuation is not shown. In addition, there is no disclosure of a method over the range of the composition ratio at the time of fluctuation assumed in practice. The same applies to the composition variation suppressing technique.

The present invention is for solving such problems, and in a mixed gas supply apparatus using an adsorbent, composition fluctuations are within a certain range within a wide range of practically assumed temperatures and mixed gas composition ratios. It is an object of the present invention to provide a mixed gas supply device that can supply gas while suppressing the pressure to the minimum. The gist of the present invention is as follows. That is,
The invention of claim 1 includes a supply line that supplies a mixed gas whose composition changes over time, a parallel pipe section that includes a plurality of branch pipes in the supply line path, and each branch pipe path. A plurality of packed towers that are arranged and filled with adsorbents each having different adsorption characteristics, an optimal packed tower selection means that selects a packed tower that minimizes the amount of composition fluctuation at the outlet of the packed tower, and a mixed gas flow path are selected. It is a mixed gas supply apparatus characterized by comprising flow path switching means for switching appropriately on the optimum packed tower side.

In the present invention, the “composition variation amount” is an amount in which the concentration of a component temporarily changes from the concentration to be supplied when attention is paid to a certain component in the mixed gas. That is, it is not necessarily limited to the composition variation amount of all components in the mixed gas, and may be a variation amount focusing on the variation of the control target.
In the present invention, the “mixed gas” is a concept including a raw material gas, a by-product gas, an exhaust gas, a produced gas by biomass, and the like in the chemical industry.
In addition, as the “adsorbent” used in the present invention, 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.

In the above invention, as the optimum packed tower selection means, it is possible to use a difference in the composition fluctuation amount with respect to the combination of the composition ratio of the mixed gas and the environmental temperature for each adsorbent (claim 2).

  According to the present invention, it is possible to select an optimum packed column corresponding to any combination of composition ratio and ambient temperature. The calorific value fluctuation range can be obtained by obtaining adsorption characteristics under each condition for each adsorbent used in advance.

The invention of claim 3 is a supply line for supplying fuel gas in which the calorific value of the component fluctuates over time,
A parallel pipe section having a plurality of branch pipes in the supply line path, a plurality of packed towers arranged in each branch pipe path and filled with adsorbents having different adsorption characteristics, and fuel for each adsorbent Select the optimum packed tower selection means and fuel gas flow path to select the packed tower that minimizes the amount of heat generation fluctuation at the outlet of the packed tower using the difference in the composition fluctuation amount with respect to the combination of the gas composition ratio and the environmental temperature. A fuel gas calorific value adjustment device comprising a flow path switching means for switching appropriately on the optimum packed tower side.
In the said invention, it can be set as city gas which has methane as a main component as "fuel gas" (Claim 4).
Currently, city gas nationwide is classified into 14 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 Wobbbe index (WI) is a numerical value obtained by dividing the calorific value H (MJ / m3) of the gas by the square root of the specific gravity s of the gas with respect to air.
WI = H / √s
This is an index of complete combustibility of gas equipment.
The combustion rate index (MCP) is expressed by the following equation.

上式において、Ｓｉ、ｆｉはそれぞれ都市ガス中の各可燃性ガスの燃焼速度及び係数、Ａｉは都市ガス中の各可燃性ガスの含有率（体積百分率）、Ｋは減衰係数である。各係数の具体的数値についてはガス事業法に示されているため、ここでは省略する。
従って、本発明において燃料ガス供給装置通過後の混合ガスのＷＩ及びＭＣＰを、例えば１３Ａ都市ガスの範囲とするように、適宜、充填塔を切り替えることにより、供給域内で都市ガス１３Ａ用機器を良好に燃焼させることができる。

In the above equation, Si and fi are the burning rate and coefficient of each combustible gas in the city gas, Ai is the content (volume percentage) of each combustible gas in the city gas, and K is the attenuation coefficient. Specific numerical values for each coefficient are shown in the Gas Business Law, and are therefore omitted here.
Therefore, in the present invention, by appropriately switching the packed tower so that the WI and MCP of the mixed gas after passing through the fuel gas supply device are in the range of, for example, 13A city gas, the equipment for city gas 13A is improved in the supply area. Can be burned.

According to a fifth aspect of the present invention, in the mixed gas supply apparatus, the composition fluctuation suppressing method is characterized by appropriately switching the flow path to a packed tower that minimizes the composition fluctuation width in response to the composition fluctuation of the mixed gas. It is.
According to a sixth aspect of the present invention, in each of the calorific value adjustment devices, the flow path is appropriately switched to a packed tower that minimizes the calorific value fluctuation range in response to fluctuations in the calorific value of the fuel gas. This is a method for suppressing variation in quantity.

According to the present invention, it is possible to provide a mixed gas supply apparatus that can supply gas while minimizing composition fluctuations in a wide range of environmental temperatures and fluctuation gas composition ratios.
Further, in the invention using fuel gas as a mixed gas, even when a gas with fluctuation in calorific value is supplied from a supplier, heat is generated within a wide range of environmental temperatures and gas composition ratios at the time of fluctuation. It is possible to supply to customers with minimal fluctuations in quantity.

Hereinafter, an embodiment 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 the present embodiment, the amount of heat generated is adjusted by using a fuel gas (LNG raw material) whose composition changes over time as a “mixed gas”.
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, a vaporizer 3, two adsorbent packed towers 2a and 2b arranged in parallel in the path of the branch pipes L3 and L4, and a load device at the end of the supply line. 5 (for example, a gas engine). The LNG storage tank 4 stores LNG carried by a tank truck (not shown). The devices are connected by pipes L1 to L5. The packed tower 2a is filled with the adsorbent Xa, and the packed tower 2a is filled with the adsorbent Xb. The adsorbents Xa and Xb have different adsorption characteristics as will be described later. Switching valves Va and Vb are disposed on the upstream side of the packed towers of the branch pipes L3 and L4, respectively. A gas composition measuring unit 6 is disposed in the pipe L2 path, and is configured to measure the composition of the mixed gas passing therethrough. Furthermore, temperature sensors Sa and Sb are disposed inside the packed tower, and are configured to measure the environmental temperature of the adsorbent.

Furthermore, the fuel gas supply apparatus 1 includes a control unit 7 that performs heat generation amount adjustment control. Based on the heat generation amount fluctuation range after passing through the adsorbents Xa and Xb with respect to the combination of the mixed gas composition and the environmental temperature (hereinafter referred to as supply conditions), the control unit 7 minimizes the fluctuation range when passing through any packed tower. An operation table for selecting the above is provided. Thus, the optimum packed tower is selected based on the measured values from the gas composition measuring device 6 and the temperature sensors Sa and Sb.
Next, the contents of the calculation table for selecting the optimum packed tower will be described. As a premise, the supplied fuel gas is based on the composition shown in Table 1, and a mixed gas of propane and butane having an arbitrary composition is added at the time of fluctuation.

FIG. 2 is a diagram conceptually showing the calculation table. That is, as the calculation table, data plotting the temperature dependence of the calorific value fluctuation range ΔH for the adsorbents Xa and Xb using the propane concentration r in the fluctuation component as a parameter is used. The calorific value fluctuation range ΔH is a physical quantity represented by ΔH = (Hmax−Hmin) / 2, that is, 1/2 of the difference between the calorific value maximum value Hmax and the minimum value Hmin.
In the figure, the smaller the value of ΔH after passing through the packed tower, the higher the calorific value fluctuation suppressing performance. For example, when the environmental temperature = T1 and r = 0.6, the heat generation amount fluctuation range is ΔHa for the adsorbent Xa and ΔHb for the adsorbent Xb. Therefore, by comparing ΔHa and ΔHb, the adsorbent packed tower having a smaller value is the optimum packed tower.
The control unit 7 is configured to select the optimum packed tower using the calculation table based on the measured values from the gas composition measuring device 6 and the temperature sensors Sa and Sb.

Next, the heat generation amount adjustment control flow in this embodiment will be described with reference to FIG. In the initial setting stage, the switching valve Va is set to open and Vb is closed (S101). The composition ratio of the fuel gas and the ambient temperature around the packed tower are measured (S102). Next, based on the measured values and the above-described calculation table, the heat generation amount fluctuation range after passing through the packed tower is calculated (S103), and ΔHa and ΔHb are compared (S104). When ΔHa is smaller, the switching valve Va is opened so as to pass through the packed tower 2a (S105). When ΔHa> ΔHb, Vb is open and Va is closed, and the mixed gas is set so as to pass through the packed tower 2b (S106).
By performing the above control at a predetermined interval, the load gas is supplied with the fuel gas in which the calorific value fluctuation is suppressed.

  Moreover, although the form which arrange | positions two adsorbent packed towers in parallel was shown in this embodiment, it can also be set as the form which arrange | positions three or more packed towers in parallel, and is filled with a respectively different adsorbent.

In order to confirm the effect of suppressing the amount of heat generation fluctuation according to the present invention, the following tests were conducted.
(Test adsorption material)
Two types of adsorbents, ie, coal raw material activated carbon and coconut shell raw material activated carbon were used (hereinafter, the coal raw material activated carbon may be abbreviated as activated carbon A and the coconut shell raw material activated carbon may be referred to as activated carbon B). The physical properties of the activated carbons A and B are shown in Table 2, and the pore size distribution (by nitrogen adsorption DFT method) is shown in FIG. FIG. 5 shows the pressure-adsorption amount characteristics of activated carbons A and B with respect to methane and propane.

(Test gas)
Three types of test gases shown in Table 3 were used. In the figure, for example, the test gas 2 is periodically flown by flowing a 100% LNG vaporized gas for 2 minutes and then adding a gas for addition (propane: butane≈1: 1) to this gas for 1 minute. It is a gas whose composition (calorific value) varies. The composition of the LNG vaporized gas is CH4: 90.8%, C2H6: 5.0%, C3H8: 3.0%, i-C4H10: 0.6%, and n-C4H10: 0.6%. The right column of the table shows the maximum value and minimum value of the calorific value on the inlet side of each test gas, and the calorific value fluctuation range ΔH ₀ .

(Test equipment and test method)
Filled containers (total volume 30 cc) with coal-activated carbon or coconut shell activated carbon and kept the container temperature at 2 ° C., 25 ° C., 40 ° C., 60 ° C., 80 ° C. The test gas flowed into the packed container at a superficial velocity of 2000 h- ¹ . During this time, the calorific value of the gas before and after the container was measured with a calorimeter (product name: GasPT, manufactured by Advantica), and the fluctuation range ΔH was determined for each temperature condition.

(Measurement result)
FIG. 6 is a graph comparing the temperature dependence of the fluctuation range ΔH of the coal raw material activated carbon and the coconut shell raw material activated carbon for the test gas 1. From this figure, it can be seen that the coal raw activated carbon has a smaller fluctuation range (higher suppression performance) at about 40 ° C. or less, but reverses when this temperature is exceeded.
FIG. 7 is a diagram showing a similar comparison for the test gas 2. In this case, about 20 ° C. is the temperature at which the material with high suppression performance changes. FIG. 8 is a diagram showing a similar comparison for the test gas 3. In this case, it is understood that the fluctuation range of the coal raw material activated carbon is smaller in most temperature ranges.
Based on the measurement results, when the activated carbon having a small fluctuation range under each condition is selected using the composition ratio of the additive gas and the environmental temperature as a matrix, Table 4 is obtained. Table 4 can also be used as the “packed tower determination table” described above.
In this example, the composition ratio of the additive gas was measured in three steps and the temperature was measured in five steps. However, by obtaining measurement data that further subdivides each element, it is possible to select with higher accuracy. Become.

  The present invention is not limited to the suppression of fluctuations in the calorific value of fuel gas, but is widely applicable to the suppression of the composition of mixed gas composed of a plurality of gas components whose composition varies, such as raw material gas, by-product gas, exhaust gas, and produced gas by biomass in the chemical industry. Is 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 a figure which shows notionally the calorific value fluctuation width calculation table in a packed tower exit. It is a figure which shows the emitted-heat amount adjustment control flow in the fuel gas supply apparatus. It is a figure which shows the pore size distribution of activated carbon A and B which are test adsorption materials. It is a figure which shows the pressure-adsorption amount characteristic with respect to methane and propane of activated carbon A and B. It is the figure which compared the temperature dependence of the fluctuation range in the packed tower exit of the coal raw material activated carbon and the coconut shell raw material activated carbon about the test gas 1. FIG. It is the figure which compared the temperature dependence of the fluctuation range in the packed tower exit of the coal raw material activated carbon and the coconut shell raw material activated carbon about the test gas 2. FIG. It is the figure which compared the temperature dependence of the fluctuation range in the packed tower exit of the coal raw material activated carbon and the coconut shell raw material activated carbon about the test gas 3. FIG. It is a figure which shows the structure of the conventional calorific value adjustment apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel gas supply apparatus 2a, 2b ... Packing tower 3 ... Vaporizer 4 ... LNG storage tank 5 ... Load device 6 ... Gas composition measurement part 7- ... Control units L1 to L5 ... Pipe Sa, Sb ... Temperature sensors Va, Vb ... Switch valves Xa, Xb ... Adsorbents

Claims (6)

A supply line for supplying a mixed gas whose component composition varies over time;
A parallel pipe section having a plurality of branch pipes in the supply line path;
A plurality of packed towers arranged in each branch pipe path and filled with adsorbents having different adsorption characteristics;
An optimum packed column selecting means for selecting a packed column that minimizes the amount of composition fluctuation at the packed column outlet;
A flow path switching means for appropriately switching the mixed gas flow path to the selected optimum packed tower side; and
A mixed gas supply apparatus comprising: 2. The mixed gas supply apparatus according to claim 1, wherein the optimum packed column selecting unit is a unit that uses a difference in composition variation with respect to a combination of a mixed gas composition ratio and an environmental temperature for each adsorbent. 3. A supply line for supplying fuel gas in which the calorific value of the component fluctuates over time;
A parallel pipe section having a plurality of branch pipes in the supply line path;
A plurality of packed towers arranged in each branch pipe path and filled with adsorbents having different adsorption characteristics;
Optimum packed tower selection means for selecting a packed tower that minimizes the calorific value fluctuation amount at the outlet of the packed tower using the difference in the composition fluctuation amount with respect to the combination of the fuel gas composition ratio and the environmental temperature for each adsorbent;
A flow path switching means for appropriately switching the fuel gas flow path to the selected optimum packed tower side; and
An apparatus for adjusting a calorific value of fuel gas, comprising: The calorific value adjusting device according to claim 3, wherein the fuel gas is a city gas mainly composed of methane. The mixed gas supply apparatus according to claim 1 or 2,
A composition fluctuation adjusting method, wherein the flow path is appropriately switched to a packed tower that minimizes the composition fluctuation width corresponding to the composition fluctuation of the mixed gas. In the calorific value adjusting device according to claim 3 or 4,
A calorific value fluctuation adjusting method, wherein the flow path is appropriately switched to a packed tower that minimizes the calorific value fluctuation range in response to the calorific value fluctuation of the fuel gas.

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