Method for stopping operation of a heat quantity adjustment device

Abstract

To provide a method for stopping operation which is capable of preventing liquid drop when the operation of a calorific value adjusting device is stopped.SOLUTION: There is provided a method for stopping operation of a calorific value adjusting device 1. The calorific value adjusting device 1 comprises: an outer cylinder 5 that is provided in a main pipe 3 through which gas flows and that receives a supply of the gas from a proximal end side and ejects the gas to a distal end side; an inner cylinder 9 arranged in the outer cylinder 5 in a coaxial direction with the outer cylinder 5 and with a space therebetween and receiving the gas from a branch pipe 7 branched from the main pipe 3; a liquid nozzle 13 that is arranged coaxially with the inner cylinder 9 and that discharges liquid into the inner cylinder 9, that adjusts a calorific value of gas by adding liquid from the liquid nozzle 13 to the gas flowing through the main pipe 3, and that is installed so that the downstream side of outer cylinder 5 faces downward. By the method, a supply of liquid to the liquid nozzle 13 is stopped, then a supply of gas to the inner cylinder 9 is stopped, and then a supply of gas to the outer cylinder 5 is stopped.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for stopping an operation of a calorific value adjusting device that adjusts the calorific value of gas by adding liquid from a liquid nozzle to the gas flowing through a mainstream pipe. [Background technology]

[0002] The calorific value of city gas is adjusted by vaporizing and mixing liquefied petroleum gas (LPG) with natural gas (NG), which is made by vaporizing liquefied natural gas (LNG). In recent years, imports of LNG with a high methane content, such as shale gas, have increased, and the calorific value of LPG tends to increase.

[0003] Such a method for adjusting the amount of heat can be carried out using, for example, the "fluid atomization nozzle device" disclosed in Patent Document 1. Patent Document 1 discloses, as an embodiment of a fluid atomization nozzle device, a calorific value adjusting device that produces city gas by adding LPG (liquid) to NG (gas). 4, this calorific value adjustment device 1 includes an outer cylinder 5 made of a Venturi tube provided in a mainstream pipe 3 through which NG flows, a branch pipe 7 branching off from the mainstream pipe 3, an inner cylinder 9 disposed within the outer cylinder 5 and receiving a supply of NG from the branch pipe 7, and a liquid nozzle 13 provided within the inner cylinder 9 and receiving a supply of LPG from a liquid supply pipe 11, and adjusts the calorific value of the NG by adding LPG from the liquid nozzle 13 to the NG flowing through the mainstream pipe 3 (see paragraph

[0042] of Patent Document 1).

[0004] Since multiple lines are provided to city gas demand destinations, and the above-mentioned calorie adjustment device 1 is provided on each line, operation of the calorie adjustment device 1 installed on some lines is stopped depending on the demand amount of the demand destination. Furthermore, the operation of the heat quantity adjustment device 1 may be stopped for maintenance.

[0005] Patent Document 1 does not mention a method for stopping the operation of the heat quantity adjustment device 1. However, since it is necessary to minimize the flow rate of gas downstream, which has unstable heat content, when shutting down the plant, the shutdown method was to (1) stop the supply of NG to the main pipe 3, (2) stop the supply of LPG from the liquid supply pipe 11 to the liquid nozzle 13, and (3) stop the supply of NG from the branch pipe 7 to the inner tube 9. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-206071 Summary of the Invention [Problem to be solved by the invention]

[0007] The installation posture of the heat quantity adjustment device disclosed in Patent Document 1 may vary depending on the layout of the installation location, and for example, the Venturi tube may be installed horizontally, vertically, diagonally downward, or the like. The heat quantity adjustment device 1 disclosed in Patent Document 1 is premised on the Venturi tube being installed horizontally, and it has not been demonstrated whether the heat quantity can be adjusted normally when the device is installed vertically, i.e., vertically or diagonally downward. Therefore, the inventors conducted an operation experiment by installing the Venturi tube facing vertically downward, and found that when operation was stopped, an unstable flow caused by gravity caused LPG that had accumulated in the vertical pipe of the liquid supply pipe 11 to fall, resulting in a liquid drop phenomenon.

[0008] If liquid dripping occurs when the plant is shut down, the LPG will flow out in an unatomized liquid state and remain in the downstream piping. This causes the remaining LPG, which has a high calorific value, to vaporize when the plant is shut down and when it is next started, which has a negative impact on calorific value adjustment.

[0009] The present invention has been made to solve the above problems, and has as its object to provide a method for shutting down an operation of a heat quantity adjustment device that can prevent liquid dripping when the device is shut down. [Means for solving the problem]

[0010] The present invention provides a calorific value adjustment device comprising: an outer cylinder disposed in a mainstream pipe through which a gas flows, receiving a supply of the gas from a base end side and spraying the gas toward a tip end side; an inner cylinder disposed within the outer cylinder coaxially with the outer cylinder and with a space between it and the inner wall of the outer cylinder, receiving a supply of the gas from a branch pipe branching off from the mainstream pipe; and a liquid nozzle disposed coaxially with the inner cylinder and discharging a liquid into the inner cylinder, the calorific value of the gas being adjusted by adding a liquid from the liquid nozzle to the gas flowing through the mainstream pipe, and a method for stopping the operation of a calorific value adjustment device disposed so that the downstream side of the outer cylinder faces downward, the method comprising stopping the supply of liquid to the liquid nozzle, then stopping the supply of gas to the inner cylinder, and then stopping the supply of gas to the outer cylinder. [Effects of the Invention]

[0011] According to the present invention, when operation is stopped, the liquid is prevented from falling and accumulating downstream of the outer cylinder in a liquid state, thereby preventing adverse effects on heat adjustment after operation is stopped or at the next startup due to liquid accumulation. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 3 is an explanatory diagram of a method for stopping the operation of the heat quantity adjustment device according to the embodiment of the present invention. [Figure 2] 1 is an explanatory diagram of a heat quantity adjustment device according to an embodiment of the present invention; [Figure 3] 1 is an explanatory diagram illustrating a conventional method for stopping the operation of a heat quantity adjustment device and the reason why liquid drops occur. [Figure 4] FIG. 1 is an explanatory diagram illustrating an overview of a conventional heat quantity adjustment device. DETAILED DESCRIPTION OF THE INVENTION

[0013] Before explaining the method for shutting down the heat quantity adjustment device according to this embodiment, an overview of the heat quantity adjustment device will be explained based on FIG. 2, and then a conventional method for shutting down the device and the reason why the liquid dripping phenomenon occurs will be outlined, and then this embodiment will be explained.

[0014] <Explanation of the heat regulator> The heat quantity adjustment device 1 according to this embodiment will be described based on FIG. 2. Since its basic structure is the same as that of the conventional example shown in FIG. 4, the same parts in FIG. 2 as those in FIG. 4 are given the same reference numerals.

[0015] As shown in FIG. 2 , the calorific value adjustment device 1 according to this embodiment includes an outer cylinder 5, such as a Venturi tube, that is provided in a mainstream pipe 3 through which a gas such as NG flows, receives a supply of gas from the base end and sprays it out toward the tip end, an inner cylinder 9 that is arranged coaxially with the outer cylinder 5 within the outer cylinder 5 with a space between it and the inner wall of the outer cylinder 5 and receives a supply of gas from a branch pipe 7 that branches off from the mainstream pipe 3, and a liquid nozzle 13 that is arranged coaxially with the inner cylinder 9 and discharges a liquid such as LPG that is supplied from a liquid supply pipe 11 into the inner cylinder 9, and adjusts the calorific value of the gas by adding liquid from the liquid nozzle 13 to the gas flowing through the mainstream pipe 3. The main pipe 3 is provided with a main valve 15, the branch pipe 7 is provided with a branch valve 17, and the liquid supply pipe 11 is provided with a liquid valve 19.

[0016] The positional relationship of liquid nozzle 13 to inner cylinder 9 in this embodiment is the same as the positional relationship of inner cylinder 9 to outer cylinder 5, in that liquid nozzle 13 is disposed within inner cylinder 9 coaxially with inner cylinder 9 and with a space between it and the inner wall of inner cylinder 9 (see FIG. 2). However, the liquid nozzle of the present invention is not limited to being disposed in this manner, and as described above, it may be any liquid nozzle that is disposed coaxially with inner cylinder 9 and that discharges liquid such as LPG supplied from liquid supply pipe 11 into inner cylinder 9.

[0017] Furthermore, it is assumed that the heat quantity adjustment device 1 of this embodiment is installed so that the downstream side of the outer cylinder 5 faces downward.

[0018] <Explanation of conventional shutdown methods and liquid dripping phenomenon> Next, the conventional method for shutting down the operation and the reason why the liquid dripping phenomenon occurs will be explained with reference to FIG. The state shown in FIG. 3(a) is the operating state, similar to FIG. 2, in which main valve 15, distribution valve 17 and liquid valve 19 are all open. When the system is shut down from this operating state, the main valve 15 is first closed as shown in Fig. 3(b). As mentioned above, this is because, in order to minimize the flow rate of gas downstream, which becomes unstable in terms of heat quantity when the system is shut down, it is necessary to stop the flow of NG in the main pipe 3, which has the highest flow rate. In this state, NG and LPG are supplied to the outer casing 5 from the branch pipe 7.

[0019] Next, the liquid valve 19 is closed (see FIG. 3(c)). At this time, as shown in FIG. 3(c), NG is flowing inside the inner cylinder 9, so the pressure inside the inner cylinder 9 is high and the pressure outside the inner cylinder 9 is low. Therefore, the pressure difference causes the LPG to be blocked at the tip of the liquid nozzle 13. In other words, in this state, LPG remains in the area from the liquid valve 19 to the tip of the liquid nozzle 13.

[0020] Next, when the distribution valve 17 is closed (see FIG. 3(d)), the blocked LPG flows out all at once due to gravity, as shown in FIG. 3(d). The amount that flows out is the amount that falls due to gravity between the liquid nozzle 13 and the liquid valve 19 in the liquid supply pipe 11.

[0021] As mentioned above, if liquid dripping occurs when the plant is shut down, LPG will flow into the downstream piping without being atomized and will remain there without vaporizing, which will have a negative impact on the adjustment of heat quantity when the plant is shut down and when it is next started up.

[0022] <Operation Shutdown Method of the Present Embodiment> The above-described conventional shut-down method is carried out from the viewpoint of minimizing the flow rate of gases downstream that cause unstable heat quantity. However, if the liquid drip phenomenon occurs, LPG will accumulate in a liquid state inside the main pipe 3 downstream of the outer cylinder 5, which will have a significant impact on the adjustment of the calorific value when the system is stopped or when it is next started up. Therefore, in this embodiment, it is possible to prevent the LPG from remaining in a liquid state on the downstream side of the outer cylinder 5 .

[0023] A method for stopping the operation of a heat quantity adjustment device according to this embodiment will be described with reference to Fig. 1. In Fig. 1, the device configuration is the same as that shown in Fig. 2 and Fig. 3, so the same reference numerals as in Fig. 3 are used and the description will be omitted. In the method for stopping the operation of the calorie adjustment device according to this embodiment, first, the liquid valve 19 is closed (see FIG. 1(b)) from the operating state shown in FIG. 1(a). In this state, as shown in FIG. 1(b), the supply of LPG is stopped, but LPG is held at the tip of the liquid nozzle 13 by the differential pressure.

[0024] Next, the branch valve 17 is closed to stop the supply of NG to the branch pipe 7 (see FIG. 1(c)). In this state, as shown in FIG. 1(c), the supply of NG to the inner cylinder 9 is stopped, eliminating the pressure difference and causing the LPG trapped in the liquid nozzle 13 to fall by gravity. However, since NG from the main pipe 3 continues to be supplied to the outer cylinder 5, the LPG that falls in liquid form is vaporized at the outlet of the inner cylinder 9 and flows downstream. Next, as shown in Figure 1(d), when the accumulated LPG has completely evaporated, the main valve 15 is closed to stop the supply of NG from the main pipe 3 to the outer cylinder 5. The time from when the minor valve 17 is closed to when the main valve 15 is closed can be determined in advance depending on the scale of the facility and the amount of accumulated LPG, but is, for example, about 2 minutes.

[0025] As described above, according to this embodiment, LPG is prevented from falling to the downstream side of the outer cylinder 5 and remaining in a liquid state, and adverse effects on heat quantity adjustment after operation is stopped or at the next operation time due to the retention of low-temperature LPG can be prevented. [Explanation of symbols]

[0026] 1 Heat adjustment device 3 Main pipe 5 outer cylinder 7 Branch Pipe 9 Inner cylinder 11 Liquid supply pipe 13 Liquid nozzle 15 Main valve 17-minute valve 19 Liquid valve

Claims

[Claim 1] A calorific value adjustment device comprising: an outer cylinder disposed in a mainstream pipe through which gaseous natural gas flows, the outer cylinder receiving a supply of the natural gas from a base end side and spraying it out toward a tip end side; an inner cylinder disposed within the outer cylinder coaxially with the outer cylinder and with a space between it and the inner wall of the outer cylinder, receiving a supply of the natural gas from a branch pipe branching off from the mainstream pipe and supplying the natural gas into the outer cylinder; and a liquid nozzle disposed coaxially with the inner cylinder and discharging liquefied petroleum gas (LPG) into the inner cylinder, the calorific value of the natural gas being adjusted by adding liquefied petroleum gas from the liquid nozzle to the natural gas flowing through the mainstream pipe, the method for stopping operation of the calorific value adjustment device being installed so that the downstream sides of the outer cylinder, the inner cylinder, and the liquid nozzle face downward, comprising: A method for stopping the operation of a heat quantity adjustment device, characterized by stopping the supply of liquefied petroleum gas to the liquid nozzle, causing the liquefied petroleum gas to be blocked at the tip of the liquid nozzle, then stopping the supply of natural gas to the inner cylinder, causing the blocked petroleum gas to fall into the outer cylinder and vaporize, and then stopping the supply of natural gas to the outer cylinder.

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