JP2005326048A - Heat quantity fluctuation control system and method for delivered fuel gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat quantity fluctuation control system and a heat quantity fluctuation control method of a fuel gas for delivering the fuel gas while easily and surely adjusting its heat quantity and combustibility in delivering the fuel gas to a demander. <P>SOLUTION: In this heat quantity fluctuation control system and method for delivered fuel gas, a branch pipe provided with a heavy component evacuation pipe or a container, is mounted on a fuel gas outlet-side conduit pipe from a vaporizer, and the heavy component is allowed to be evacuated to the heavy component evacuation pipe or container by using LNG liquid from a storage tank in starting the vaporizer, thus the fresh LNG is filled in the pipe to the vaporizer in a replaced manner, and the rise of heat quantity is controlled. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  More particularly, the present invention relates to a heat amount fluctuation suppressing system and a heat amount fluctuation suppressing method for a delivery fuel gas, and more particularly, to a heat quantity fluctuation suppressing system and a heat amount fluctuation of a delivery fuel gas to be applied to a consumer or used for private use. It relates to a suppression method.

  There are city gas and natural gas as hydrocarbon fuel gas. Of these, natural gas contains hydrocarbon gases such as ethane, propane, and butane that are heavier than methane, especially in petroleum-based natural gas and structural natural gas, depending on the production area. As an example, methane = 90.38% (mol%, the same applies hereinafter), ethane = 4.55%, propane = 3.31%, i-butane = 0.73%, n-butane = 0.94%, i -Pentane = 0.03%, n-pentane = 0.01%.

  When supplying natural gas to a consumer in an area where a gas conduit is not laid, a small gas delivery base (hereinafter referred to as a satellite base) is installed in the vicinity of the consumer to perform gas delivery. The satellite base has a liquefied natural gas (Liquefied Natural Gas, abbreviated as “LNG” where appropriate in the present specification and claims), a LNG vaporizer, Other disaster prevention facilities are installed.

  FIG. 1 is a diagram for explaining the mode. As shown in FIG. 1, LNG transported from a LNG receiving terminal such as a port by means of transportation such as a dedicated tank lorry (automobile) or tank container (railway) is stored in the LNG storage tank of the satellite base and stored in the LNG storage tank. LNG is vaporized by a carburetor and supplied to a gas engine and other various gas combustion devices on the consumer side for consumption.

  Here, the LNG storage tank of the satellite base and the large-scale LNG storage tank of the LNG receiving base in a port or the like are different in scale and specification. The LNG storage tank at the satellite base is designed with a higher pressure than the storage tank at the receiving base. Generally, a heat insulating outer layer is filled with a heat insulating material such as pearlite, and this is maintained at normal pressure or in a vacuum state. A vertical cylindrical storage tank with room temperature insulation is used. A pressure evaporator is disposed adjacent to the LNG storage tank at the satellite base, thereby controlling the pressure of the LNG storage tank in a range of approximately 0.3 to 0.9 MPaG. The pressure is higher than 10 kPaG).

  As described above, LNG is transported from the receiving base and received in the LNG storage tank of the satellite base. At that time, since the operating pressure of the LNG storage tank is high as described above, the LNG in the LNG storage tank is held in a supercooled state after the reception. As a result, sufficient time is secured until the saturation temperature is reached due to the intrusion heat into the LNG storage tank, so that generation of boil-off gas can be ignored at the satellite base.

  By the way, as a vaporizer disposed following the LNG storage tank of the satellite base, a simple air vaporizer (with air fins) is frequently used. FIG. 2 is a diagram showing an example of an air temperature type vaporizer with air fins for the liquefied natural gas. As shown in FIG. 2, a plurality of heat transfer tubes with heat transfer fins are arranged and connected to upper and lower headers (pipe headers), respectively, and LNG is evaporated by the air around the heat transfer tubes by passing from the lower part in the heat transfer tubes. . The evaporation is facilitated by heat transfer fins.

  However, such an air-fin type air vaporizer with air fins cannot be operated continuously due to a decrease in temperature due to icing on the heat transfer fins. For this reason, it is common to ensure the number of vaporizers of 150% or more with respect to the required capacity. FIG. 3 is a diagram showing the arrangement. As shown in FIG. 3, a pressure evaporator, an LNG storage tank, and a plurality of vaporizers are sequentially arranged via a pipe. The pressure of the LNG storage tank is controlled by a pressure evaporator disposed adjacent to the LNG storage tank. LNG from the LNG storage tank is distributed from a pipe 1 to a plurality of vaporizers, and natural gas vaporized by the plurality of vaporizers is sent to a consumer from a pipe 2 provided with a delivery valve.

  In such an arrangement mode, the carburetor performs an operation of setting an appropriate operation time and an ice-breaking time and sequentially switching a plurality of carburetors at regular time intervals. However, when the carburetor is started, there is a considerable change in the calorie of the outgas, that is, the gas supplied to the consumer, in particular, an increase in the calorie. Such fluctuations in the amount of heat are not a problem for general combustion equipment such as a boiler or a combustion furnace, but are a problem for combustion equipment for cogeneration such as a gas engine.

  As described above, natural gas contains hydrocarbon gases such as ethane, propane, and butane that are heavier than methane. As a result, while light methane and ethane evaporate early in the vaporizer, the evaporation of heavy propane and butane is delayed, and these heavy components (this specification and claims) (Also referred to as “heavy” in the range) stays in the conduit upstream of the vaporizer. Due to this stagnation, a high amount of heat supply gas is generated for a certain time when the vaporizer is started.

  For this reason, currently, measures such as providing a large capacity cushion tank downstream of the vaporizer or releasing a gas with a high calorific value at the start of delivery are taken, and measures are taken to mitigate fluctuations in the calorific value. . However, when starting one of the multiple carburetors, the effect of dilution due to the gas emitted from the carburetor is obtained during operation, so the fluctuation of heat is mitigated, but the initial start, that is, the gas supply amount is zero. When the carburetor starts up from the state, the amount of heat fluctuation is extremely large, and due to the increase in heat amount due to heavy components, the type of combustion equipment used by consumers, especially gas engines, will adversely affect the operation of equipment. May become gas.

  That is, an increase in the amount of heat is caused by the fact that propane and butane, among the heavy components contained in LNG, mainly stay in a high concentration in a partial conduit upstream of the vaporizer. If it says in FIG. 3, it is a location shown with the dashed-dotted line in FIG. Of the LNG components remaining in the conduit, methane, which has a low boiling point, is easily vaporized by external heat input, whereas high boiling components, ie, heavy components (propane and butane, especially butane) are contained in the conduit. It tends to remain in a liquid state. For this reason, the ratio of the heavy component in LNG remaining in the conduit is relatively high. When the vaporizer is started, the liquid of the heavy component staying in the conduit is pushed out by the LNG from the LNG storage tank, so that a gas with a high heat quantity is locally generated at the initial start, and the heat quantity rises. .

The present invention solves the above-described problems. When a fuel gas is sent to a consumer, the calorific value fluctuation suppression system and the calorie of the fuel gas that are easily and surely adjusted for the calorific value and the combustibility are sent. The object is to provide a fluctuation suppressing method. The present inventors have developed and filed an invention that solves the same kind of problem by different means (Japanese Patent Application No. 2004-060796).
Japanese Patent Application No. 2004-060796

  The present invention is (1) a system for suppressing fluctuations in the amount of heat of fuel gas sent from a vaporizer following an LNG storage tank, and a pipe for evacuating heavy components into a pipe branched from a pipe for sending LNG from the LNG storage tank to the vaporizer Alternatively, by placing a heavy component evacuation container and evacuating the heavy component to the heavy component evacuation pipe or heavy component evacuation container using the LNG liquid from the LNG storage tank when the vaporizer is started, A system for suppressing variation in the calorific value of the delivery fuel gas is provided, in which the inside of the pipe leading to is replaced with fresh LNG to suppress an increase in the calorific value.

  The present invention is (2) a method for suppressing variation in the calorific value of fuel gas sent from a vaporizer following an LNG storage tank, and a pipe for evacuating heavy components into a pipe branched from a pipe for sending LNG from the LNG storage tank to the vaporizer Alternatively, by placing a heavy component evacuation container and evacuating the heavy component into the heavy component evacuation pipe or heavy component evacuation container using the LNG liquid from the LNG storage tank when the vaporizer is started up. The present invention provides a method for suppressing the variation in the amount of heat of the delivery fuel gas, characterized in that the inside of the pipe leading to is replaced with fresh LNG to suppress an increase in the amount of heat.

  According to the present invention, by placing the heavy component evacuation pipe or the heavy component evacuation container in the pipe branched from the pipe that sends LNG from the LNG storage tank to the vaporizer, The amount of heat generation and combustibility can be easily and reliably adjusted only by the retreat operation for heavy components. As a result, fuel gas of stable quality can be sent to consumers and private use, and at the same time, the investment and cost for adjusting the calorific value can be greatly reduced. Further, according to the present invention, it is possible to stabilize the heat quantity of the fuel gas and prevent start-up congestion and poor ignition of gas combustion equipment such as a gas engine. For example, stable operation in a cogeneration system using a gas engine is achieved. be able to.

  The present invention (1) is a system for suppressing variation in the amount of heat of the fuel gas delivered from the vaporizer following the LNG storage tank. Then, a heavy component evacuation pipe or a heavy component evacuation container is arranged in a pipe branched from a pipe following the header that distributes LNG from the LNG storage tank to a plurality of vaporizers. By using the LNG liquid from the LNG storage tank to evacuate the heavy component evacuation pipe or heavy component evacuation container, the pipe leading to the vaporizer is replaced with fresh LNG, so that the rise in heat quantity is suppressed. It is characterized by becoming.

  Moreover, this invention (2) is a calorie | heat amount fluctuation | variation suppression method of the fuel gas sent from the vaporizer | carburetor following a LNG storage tank. Then, a heavy component evacuation pipe or a heavy component evacuation container is arranged in a pipe branched from a pipe following the header that distributes LNG from the LNG storage tank to a plurality of vaporizers. By using the LNG liquid from the LNG storage tank to evacuate to the heavy component evacuation pipe or heavy component evacuation container, the pipe leading to the vaporizer is replaced with fresh LNG, and the rise in heat quantity is suppressed. It is characterized by.

  FIG. 4 is a diagram showing an example of an embodiment of the present invention. As shown in FIG. 4, an LNG storage tank, a pipe 1, a carburetor header, a plurality of carburetors, and a pipe 2 for supplying fuel from each carburetor to a consumer are provided. A pressure evaporator is disposed adjacent to the LNG storage tank, whereby the pressure of the LNG storage tank is controlled in a range of approximately 0.3 to 0.9 MPaG. Pipe 3 is arranged from the carburetor header, and automatic valve A, pipe 4, flow control mechanism (orifice or needle valve), automatic valve B, pipe 5, automatic valve C, and small carburetor are arranged in order in pipe 3. The pipe 6 from the small vaporizer is connected to the pipe 2 to the customer.

  Then, branching from the pipe 4 from the automatic valve A to the flow rate control mechanism, a heavy component evacuation pipe is arranged. 7 is the branch pipe. A liquid level gauge equipped with a liquid level switch is arranged on the heavy component retreat pipe. The outlet pipe 8 from the heavy component evacuation pipe faces the pipe 9 from the LNG storage tank. The pipe 9 is connected to the atomizing line 10, and the atomizing line 10 is connected to the pipe 5 from the automatic valve B to the automatic valve C through a flow rate control mechanism (orifice or needle valve, which is indicated as a needle valve in FIG. 4). It is. The low temperature gas from the LNG storage tank flows through the atomizing line 10 and the heavy component retreated to the heavy component retreating pipe is introduced into the small carburetor downstream evenly in small amounts. The atomizing line 10 is disposed because it may be difficult to uniformly introduce the retreated heavy portion into the downstream small vaporizer in small amounts.

  The heavy component evacuation pipe may be replaced with a heavy component evacuation container, and a liquid level gauge is arranged in the same manner as in the case of the heavy component evacuation pipe. As the automatic valves A to C, general electromagnetic valves can be employed.

  In the heat quantity fluctuation suppressing system configured in this way, the automatic valves A to C are all closed before starting. At startup, the automatic valve A is opened. This opening operation is excited by releasing the closing limit of the delivery valve. The heavy component remaining in the vaporizer header is pushed into the heavy component evacuation pipe via the pipe 1 by the liquid head of the LNG storage tank. When the liquid level switch on the heavy component evacuation pipe reaches a certain level by the liquid level switch of the heavy component evacuation pipe, that is, when the liquid level exceeds the liquid level corresponding to the volume of the vaporizer header from the LNG storage tank, Closed.

  Here, for example, when the piping specification of the vaporizer header section from the LNG storage tank is 2B (inch) × 15 m, the heavy component retreat piping may be 6B (inch) × 2 m. However, since the heavy component evacuation pipe needs to be installed at a position lower than the liquid level of the LNG storage tank, strictly speaking, the height of the heavy component evacuation pipe is determined based on this.

  After that (after closing the automatic valve A), hold the delivery gas vaporized by the vaporizer for a period of time (about 10 minutes), then open the automatic valve B and the automatic valve C and open the heavy component retreat pipe The heavy portion of the LNG is discharged from the LNG storage tank along with the low-temperature gas flowing through the pipe 9 and the atomizing line 10. The heavy portion is discharged through a flow rate control mechanism (orifice or needle valve) so as not to affect the heat quantity of the delivery gas.

  When the liquid level switch of the heavy component evacuation pipe becomes low level, the automatic valves B and C are closed. Thus, according to this heat quantity fluctuation suppressing system, it is possible to complete the delivery of the heavy portion from the heavy portion evacuation pipe in about 2 hours.

  EXAMPLES Hereinafter, although this invention is demonstrated in more detail based on an Example, it cannot be overemphasized that this invention is not restrict | limited by an Example.

The present embodiment is an example implemented using the heat quantity fluctuation suppressing system shown in FIG. The calorific value of the LNG storage tank: 45 to 45.5 MJ / m ³ N, and the vaporization capacity of the vaporizer is about 1 t / h (1200 m ³ N / h in terms of gas). The heavy component in the heavy component evacuation pipe is mostly butane, and its calorific value is about 100 MJ / m ³ N. By setting the amount of gas passing through the flow paths of the pipe 5, the pipe 10, and the pipe 2 to, for example, 1: 10: 100, the amount of heat of the gas supplied to the consumer can be supplied without greatly changing.

That is, the gas amount and heat amount of the pipe 2 are 1200 m ³ N / h (45.5 MJ / m ³ N), the gas amount and heat amount of the pipe 10 are 120 m ³ N / h (45 MJ / m ³ N), and the gas of the pipe 5 The amount and the amount of heat are 12 m ³ N / h (100 MJ / m ³ N). In this case, the calorific value of the supplied gas is 45.9 MJ / m ³ N [= (1200 × 45.5 + 120 × 45 + 12 × 100) / (1200 + 120 + 12)], and the calorific value of LNG in the LNG storage tank: 45 to 45.5 MJ There is no difference even when compared with / m ³ N. Thus, according to the present invention, it is possible to stabilize the heat amount of the fuel gas accompanying the stop-start of the carburetor, and to prevent start-up congestion and poor ignition of gas combustion equipment such as a gas engine. Stable operation in a cogeneration system using a gas turbine can be achieved.

The figure explaining the installation mode of an LNG storage tank, an LNG vaporizer, etc. in a satellite base The figure which shows the example of the air temperature type vaporizer with the air fin for LNG The figure which shows the arrangement mode which secures the number of vaporizers for continuous operation The figure which shows the example of an aspect of this invention

Explanation of symbols

1-10 Piping AC Automatic valve

Claims (6)

  A system for suppressing variation in the calorific value of fuel gas delivered from a vaporizer following an LNG storage tank, and a heavy component evacuation pipe or a heavy component evacuation container to a pipe branched from a pipe that sends LNG from the LNG storage tank to the vaporizer When the vaporizer is started, the heavy component is evacuated to the heavy component evacuation pipe or the heavy component evacuation container using the LNG liquid from the LNG storage tank, so that the pipe leading to the vaporizer is fresh. A system for suppressing variation in the calorific value of the delivery fuel gas, characterized in that the LNG is replaced with LNG to suppress an increase in the calorific value.   2. The system for suppressing variation in heat quantity of a delivery fuel gas according to claim 1, wherein the delivery fuel gas is a fuel gas for combustion equipment in a cogeneration system.   3. The system for suppressing variation in the amount of heat of a delivery fuel gas according to claim 2, wherein the combustion device is a gas engine or a gas turbine.   A method for suppressing variation in calorific value of fuel gas delivered from a vaporizer following an LNG storage tank, wherein a pipe for evacuating heavy components or a container for evacuating heavy components to a pipe branched from a pipe for sending LNG from the LNG storage tank to the vaporizer When the vaporizer is started, the heavy component is evacuated to the heavy component evacuation pipe or the heavy component evacuation container using the LNG liquid from the LNG storage tank, so that the pipe leading to the vaporizer is fresh. A method of suppressing variation in the calorific value of the delivery fuel gas, characterized in that the LNG is replaced with LNG to suppress an increase in calorific value.   5. The method for suppressing variation in heat quantity of a delivery fuel gas according to claim 4, wherein the delivery fuel gas is a fuel gas for combustion equipment in a cogeneration system. 6. The method for suppressing variation in the amount of heat of a delivery fuel gas according to claim 5, wherein the combustion device is a gas engine or a gas turbine.

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