JPH0622429Y2 - Flow controller for heat quantity adjustment of city gas - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] This invention is a heat quantity adjustment in the heat quantity adjustment of city gas necessary when supplying it as city gas in a state where the quantity of heat is adjusted from a liquefied natural gas storage facility. Regarding the improvement of the device that controls the flow rate of gas, LNG vaporized gas from the storage tank B
When OG (evaporated gas) is also mixed and supplied, the amount of heat can be efficiently adjusted.

[Prior Art] When supplying liquefied natural gas (LNG) as city gas, it has to be adjusted to a certain amount of heat before being supplied.

Therefore, the conventional method of adjusting the heat quantity is LN
Liquefied petroleum gas (NPG), such as butane or propane, is mixed with G vaporized gas as a calorific value adjusting gas.

Therefore, LNG stored in the LNG storage facility in the liquid state is vaporized by using seawater or the like as a heat source.
A vaporized gas is produced and liquefied petroleum gas (LPG) having a constant calorific value with respect to the LNG vaporized gas, such as butane or propane, is mixed as a calorific value adjusting gas.

The heat quantity adjusting device for this purpose, as shown in the schematic configuration in FIG. 2, detects the flow rate of the LNG vaporized gas vaporized by the LNG vaporizer 1 by the flow rate detector 2 and calculates the ratio controller 3
The control signal of the ratio controller 3 to the LP
The flow rate of the calorific value adjusting gas from the G vaporizer 4 is output to the controller 7 of the flow rate adjusting valve 6 for detecting the flow rate of the calorific value adjusting gas to adjust the flow rate of the calorie adjusting gas to obtain the LNG vaporized gas. The calorific value adjusting gas is mixed in the mixer 8, the calorific value of the mixed city gas is measured by the calorimeter 9, and the calorific value correction signal is fed back to the ratio controller 3 based on the detected value. It has become.

On the other hand, in the LNG storage facility, the liquefied natural gas is vaporized by the heat entering from the outside, and BOG (vaporized gas) is generated. If this is not treated in some form, the pressure rise of the storage facility will occur. Therefore, if a reliquefaction device is provided to liquefy and return it to the storage facility, or as shown in FIG. 2, after pressurizing with the BOG compressor 10, if a thermal power plant or the like is adjacent, It is processed by supplying it as fuel.

[Problems to be Solved by the Invention] However, at an LNG base where such large consumption facilities for BOG (evaporative gas) are not adjacent to each other, it is dangerous to release BOG (evaporative gas) into the atmosphere. Since this wastes energy resources, it is possible to use this BOG (evaporated gas) as a raw material for city gas.

However, the amount of BOG (evaporated gas) generated fluctuates greatly, a large amount is generated when LNG is received, and the amount is decreased during the winter season, etc.
If this BOG (evaporated gas) is mixed with LNG vaporized gas and then the calorific value adjusting gas is mixed to adjust the calorific value, the control range by the ratio controller must be enlarged, and the equipment becomes large in scale. However, there are problems such as poor controllability.

The present invention has been made in view of the problems of the prior art, and even when BOG (evaporated gas) is used as a raw material of city gas, the flow rate of the heat quantity adjusting gas required for easily and efficiently adjusting the heat quantity is controlled. The present invention aims to provide a flow rate control device for adjusting the calorific value of city gas.

[Means for Solving the Problems] In order to solve the above problems, the flow rate control device for adjusting the calorific value of city gas of the present invention is an L-type device that vaporizes liquefied natural gas.
In the flow rate control device in the heat quantity adjustment of the city gas that mixes the NG vaporized gas and the BOG (evaporated gas) from the storage tank with the heat quantity adjusting gas for adjusting the heat quantity and supplies the adjusted heat quantity to the city gas conduit, the BOG ( A two-step heat amount adjusting mechanism is provided, which includes a rough adjusting mechanism that roughly adjusts the heat amount of only the evaporative gas) and a fine adjusting mechanism that finely adjusts the heat amount of the mixed gas of the coarsely adjusted BOG gas and the LNG vaporized gas after the rough adjustment. BO for detecting the flow rate of BOG (evaporated gas) by the coarse adjustment mechanism of the first stage
The G flow rate detector, the first flow rate control valve for the heat quantity adjusting gas, and the mixing amount of the heat quantity adjusting gas to be mixed based on the detection signal of the BOG flow rate detector are output to the first flow rate adjusting valve in the first period, and the heat quantity of the first stage And a controller for performing rough adjustment of the above, while the fine adjustment mechanism of the second stage detects the flow rate of the mixed gas of the coarse adjustment gas adjusted by the coarse adjustment mechanism and the LNG vaporized gas. Controller, a second flow rate control valve for heat quantity adjusting gas, a heat quantity adjustment to be mixed based on a detection signal from the mixed gas flow rate detector and a detection signal from a calorimeter for detecting the heat quantity of finally mixed city gas It is characterized in that it is configured by a controller for outputting the mixed amount of gas to the second flow rate control valve to finely adjust the heat amount in the second stage.

[Operation] According to the flow rate control device in the heat quantity adjustment of the city gas, the heat quantity of BOG (evaporated gas), which has a large variation in the generated amount, is adjusted to a substantially constant value by the coarse adjustment mechanism of the first stage, and after the coarse adjustment is performed. The coarse adjustment gas and the LNG vaporized gas are mixed, and the heat amount is adjusted for the mixed gas by the fine adjustment mechanism in the second step. The flow rate of the heat adjustment gas to be mixed is adjusted in two steps. Thus, the controllability of the heat quantity can be improved and the heat quantity can be controlled in a small control range.

[Embodiment] An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic block diagram of an embodiment of a flow rate control device for adjusting the heat quantity of city gas of the present invention.

In the flow rate control device 20 in the heat quantity adjustment of the city gas, after the first-stage coarse adjustment mechanism 30 for adjusting the heat quantity of the evaporative gas (BOG), the LNG vaporized gas, and the coarse adjustment gas after the heat quantity adjustment are mixed. , And a second-stage fine adjustment mechanism 40 for adjusting the amount of heat to produce city gas.

The coarse adjustment mechanism 30 of the first stage of the flow rate control device 20 in this heat quantity adjustment has an L level as shown in FIG.
BOG (evaporated gas) from an NG tank or the like is pressurized by the BOG compressor 31 and sent to the mixer 32, and the flow rate to the mixer 32 is detected by the BOG flow rate detector 33. There is.

On the other hand, as the heat quantity adjusting gas which is mixed with this BOG (evaporated gas) to adjust the heat quantity, butane or the like vaporized by the LPG vaporizer 34 is used, and the LPG flow rate detector 35 and the flow rate adjusting valve (first flow rate adjusting valve) are used. Mixer 32 through 36
To be sent to.

Then, the detection signal from the BOG flow rate detector 33 is input to the ratio control controller 37, and the control signal from this ratio control controller 37 is detected together with the detection signal from the LPG flow rate detector 35. Of the BOG (evaporated gas) is controlled to a substantially constant value by controlling the flow rate control valve 36 to control the mixture amount of the heat amount adjusting gas by ratio control.

In the coarse adjustment mechanism 30 of the first stage, the amount of heat of BOG (evaporated gas) is a constant value whose main component is methane.
Since the amount of OG (evaporated gas) generated fluctuates greatly, the control range for adjusting the amount of heat is wide, and the amount of heat adjusted gas such as butane with a constant amount of heat is adjusted based on the flow rate of BOG (evaporated gas). The amount of heat is adjusted by controlling the ratio.

Next, the fine adjustment mechanism 40 in the second stage adjusts the heat amount in the final stage after the LNG vaporized gas from the LNG vaporizer 41 and the coarsely adjusted gas from the mixer 32 whose heat amount has been adjusted are mixed. Yes, the mixed gas is sent to the mixer 42 via the flow rate detector 43.

Further, the heat quantity adjusting gas vaporized in the LPG vaporizer 34 is branched and sent to the mixer 42 via the LPG flow rate detector 44 and the flow rate adjusting valve (second flow rate adjusting valve) 45.

Then, the flow rate detection signal of the mixed gas from the flow rate detector 43 is input to the ratio control controller 46, and the control signal from this ratio control controller 46 is detected together with the detection signal from the LPG flow rate detector 44. It is sent to the controller 47 of the regulating valve 45, and the flow regulating valve 45 is controlled to control the calorific value of the mixed gas by the ratio control of the calorific value of the mixed gas to a substantially constant value to obtain the city gas of a predetermined calorific value. Has become.

Furthermore, a signal from the composition correction controller 48 and a detection signal from a calorimeter 49 that measures the amount of heat of city gas before being supplied to the city gas conduit are input to the ratio controller 46. We are trying to improve the control accuracy.

In the second stage fine adjustment mechanism 40, the coarse adjustment gas and LN
The calorific value of the mixed gas of the G vaporized gas is constant regardless of the mixed quantity of the roughly adjusted gas, and the calorific value of this mixed gas is also within a certain range. Therefore, the control range for the calorific value adjustment is made small, The amount of heat is finely adjusted by proportionally controlling the mixing amount of a heat amount adjusting gas such as butane having a constant amount of heat based on the flow rate of the gas.

As described above, the flow rate of the heat quantity adjusting gas is adjusted and controlled so that the BOG (evaporated gas) having a large change in the flow rate has a heat quantity in a certain range by the coarse adjusting mechanism 30 of the first step, and thereafter, the fine adjustment of the second step is performed. Since the adjustment mechanism 40 finely adjusts the flow rate of the heat quantity adjusting gas to obtain a predetermined heat quantity, it is necessary to control the flow rate of the minute heat quantity adjusting gas over a wide range by the control device having a large control range. However, it suffices to perform control for fine adjustment within a narrow range after rough adjustment, and it is possible to easily and accurately control the calorific value adjusting gas and keep the calorific value of city gas constant.

Therefore, there is no need to install a large-capacity mixing tank, BOG (evaporative gas) can be easily used as city gas, and LNG mass-emission facilities such as power plants are not adjacent to each other. It is effective as a base.

[Effect of the Invention] As described above in detail with reference to the embodiment, according to the flow rate control device for adjusting the heat quantity of city gas of the present invention, the heat quantity of BOG (evaporated gas), which has a large fluctuation in the generated quantity, can be reduced to the first quantity. The coarse adjustment mechanism of the stage adjusts to a substantially constant value, the coarse adjustment gas after the coarse adjustment and the LNG vaporized gas are mixed, and the flow rate of the heat adjustment gas is controlled by the fine adjustment mechanism of the second stage for this mixed gas. Therefore, even if BOG (evaporated gas) having a large fluctuation range is mixed, the controllability can be improved by adjusting the flow rate in two stages as compared with the case of directly controlling the flow rate of the calorific value adjusting gas. It is possible to improve and control the flow rate in a small control range, so that the heat quantity can be kept constant.

In addition, the control range of the portion where the control accuracy is required can be narrowed, and it is not necessary to increase the precision in the portion where the fluctuation range is large, and the control device can be simplified.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of a flow rate control device for adjusting the heat quantity of city gas of the present invention, and FIG. 2 is a schematic configuration diagram of a conventional device. 20: Flow rate control device for heat quantity adjustment of city gas, 3
0: first-stage coarse adjustment mechanism, 40: second-stage fine adjustment mechanism, 31: BOG compressor, 32: mixer, 33: BOG
Flow rate detector, 34: LPG vaporizer, 35: LPG flow rate detector, 36: Flow rate control valve (first flow rate control valve), 37: Ratio control controller, 38: Controller, 41: LN
G vaporizer, 42: mixer, 43: flow rate detector, 44: L
PG flow rate detector, 45: flow rate control valve (second flow rate control valve), 46: ratio control controller, 47: controller, 48: controller for composition correction, 49: calorimeter.

(72) Inventor Masayuki Asai 19-18 Sakurada-cho, Atsuta-ku, Nagoya-shi, Aichi Toho Gas Co., Ltd. (72) Takashi Yagi 3-2-16 Toyosu, Koto-ku, Tokyo Ishikawajima Harima Heavy Industries In Toyosu General Office Co., Ltd. (72) Kenji Fujita 3-21-16 Toyosu, Koto-ku, Tokyo Ishikawajima Harima Heavy Industries Co., Ltd. In Toyosu General Office

Claims (1)

[Scope of utility model registration request] 1. A city in which LNG vaporized gas obtained by vaporizing liquefied natural gas and BOG (evaporated gas) from a storage tank are mixed with a heat amount adjusting gas for heat amount adjustment, and the heat amount is adjusted to be supplied to a city gas conduit. In a flow rate control device for gas heat quantity adjustment, a coarse adjustment mechanism that roughly adjusts the heat quantity of only BOG (evaporated gas) and a fine adjustment mechanism that finely adjusts the heat quantity of a mixed gas of the rough adjusted gas after the rough adjustment and the LNG vaporized gas. A two-step heat amount adjustment mechanism is provided, and the first-step coarse adjustment mechanism is
The BOG flow rate detector for detecting the flow rate of (evaporated gas), the first flow rate adjustment valve for the heat amount adjustment gas, and the first flow rate adjustment for the mixing amount of the heat amount adjustment gas to be mixed based on the detection signal of the BOG flow rate detector. And a controller for performing a coarse adjustment of the amount of heat in the first step, while the fine adjustment mechanism in the second step is a mixed gas of the coarse adjustment gas adjusted by the coarse adjustment mechanism and the LNG vaporized gas. From the mixed gas flow rate detector for detecting the flow rate of the mixed gas, the second flow rate control valve for the calorific value adjusting gas, and the calorimeter for detecting the detection signal of the mixed gas flow rate detector and the calorific value of the finally mixed city gas. In the heat quantity adjustment of city gas, the controller is configured to output the mixed quantity of the heat quantity adjusting gas to be mixed based on the detection signal to the second flow rate adjusting valve and finely adjust the heat quantity in the second stage. Flow control device.