JPH0633865B2 - Seawater flow control method for LNG vaporizer - Google Patents

Description

The present invention relates to a seawater flow rate control method in an LNG vaporizer.

(Prior Art) In an open rack vaporizer, which is an LNG vaporizer that uses seawater as a heating source, the temperature of seawater fluctuates depending on the season, so in the past, the flow rate of seawater supplied to the LNG vaporizer was determined by the operator. Based on the temperature of seawater, a safety factor is added to set a sufficiently large amount, or the temperature of the gas in the gas header pipe of the LNG vaporizer is measured and set based on this measured temperature. .

On the other hand, when the flow rate of seawater is insufficient with respect to the LNG load, the vaporization panel gradually freezes on ice, and if left unattended, the inconvenience of the low-temperature liquid flowing into the room temperature piping occurs. In addition, conventionally, an operator monitors the icing condition of the vaporization panel by patrol or monitors the temperature of the gas in the gas header pipe.

(Problems to be Solved by the Invention) As described above, the flow rate of seawater set by the operator based on the temperature of the seawater is an amount with a sufficient margin in consideration of the safety factor. Further, even when the flow rate is set based on the temperature of the gas in the gas header pipe, the temperature of the gas at this position is an average temperature obtained by mixing the temperatures of the gases from the tubes of the vaporization panel. Therefore, when the flow rate of seawater is partially insufficient in the vaporization panel and ice is accumulating,
There is a large time delay until this is detected, and therefore the flow rate of seawater set by this method must also have a sufficient margin. As described above, in the conventional method, seawater is supplied with a sufficiently large amount set regardless of which method is applied, and thus the amount of electric power required to operate the seawater pump is consumed more than necessary. .

On the other hand, with regard to the monitoring of the insufficient flow rate of seawater, the monitoring by workers' patrol has a limited monitoring frequency, and continuous monitoring is practically impossible. However, there is a risk of overlooking the abnormality because there are individual differences in determining the abnormality. Further, in the monitoring based on the temperature of the gas in the gas header pipe, since the time delay until the detection is large as described above, it is also difficult to take prompt measures.

An object of the present invention is to solve the above problems by rationally utilizing an optical fiber distributed temperature measuring device known as a distributed temperature measuring device.

(Means for Solving the Problems) In order to solve the above problems, a seawater flow rate control method in an LNG vaporizer according to the present invention first comprises an optical fiber as a sensor of an optical fiber distributed temperature measuring device. In the LNG vaporizer to be monitored, it is installed so as to correspond to all the outlet sides of the tubes of the vaporization panel, and the average value of the temperature measured values of the outlet sides of these tubes and seawater measured by an appropriate temperature sensor The seawater flow rate control device provided in the seawater supply path to the LNG vaporizer is controlled based on the temperature.

Further, in the seawater flow rate control method in the LNG vaporizer of the present invention, the optical fiber as the sensor of the optical fiber distribution type temperature measuring device is used for all the outlet sides of the tubes of the vaporization panel in the LNG vaporizer to be monitored. And, the seawater supply route is installed in a suitable place, and the seawater flow rate control device provided in the seawater supply route is controlled from the average value of the temperature measurement values on the outlet side of the plurality of tubes and the seawater temperature. is there.

Further, in the above configuration, when the temperature measurement values on the outlet side of the plurality of tubes are not uniform, the seawater flow rate of the seawater supply route is controlled according to the minimum value of the temperature measurement values on the outlet side. It is a thing.

(Operation) In the above-described present invention, in the LNG vaporizer to be monitored, it is possible to constantly measure all the temperatures on the outlet side of the tube of the vaporization panel and the change tendency thereof. Therefore, if the temperature distribution on the outlet side is within a predetermined uniform range, that is, if the temperature distribution of the vaporization panel is uniform,
It is possible to set the required amount of seawater from the average value of the measured values of the temperature on the outlet side and the temperature of the seawater measured by an appropriate temperature sensor, and this set value is the average value and the temperature of the seawater. It can be changed in response to mobilization. In this way, by controlling the seawater flow rate control device provided in the seawater supply route with this set value, the LNG vaporizer can be operated with the minimum required flow rate of seawater throughout the year.

During such operation, if the temperature on the outlet side of the tube partially falls and the temperature distribution on the outlet side deviates from the predetermined uniform range, the temperature on these outlet sides The required amount of seawater is set from the lowest measured value and the temperature of the seawater. For this reason, the seawater is supplied at a flow rate corresponding to the portion of the vaporization panel where the flow rate is insufficient, and operation is performed in the direction in which the insufficient flow rate is eliminated.

On the other hand, it is considered that the partial decrease in the temperature on the outlet side of the tube is caused by the breakage of seawater in the vaporization panel, so an alarm is issued by the seawater flow control means that performs the above operation. A worker can inspect the LNG vaporizer and quickly perform a predetermined process.

(Example) Next, the Example of this invention is described about figures.

FIG. 1 is an explanatory view showing the configuration of the present invention, and reference numeral 1 is LN.
G vaporizer, or open rack vaporizer.
As is well known, this open rack vaporizer is a vaporization panel 5 in which tubes 4 having fins are continuously arranged in rows between an upper gas header pipe 2 and a lower liquid header pipe 3.
The seawater troughs 6 formed on the upper side of the vaporization panel 5 allow the seawater to flow down uniformly in a curtain shape.

Reference numeral 7 is a seawater supply path for supplying seawater to the seawater trough 6, 8 is a seawater pump, and 9 is a seawater flow rate control device including an orifice 10, a flow rate control valve 11 and a controller 12.

Reference numeral 12 is a seawater flow rate control means, and this seawater flow rate control means 12 is provided with an optical fiber distributed temperature measuring device known as a distributed temperature measuring device. This measuring device is composed of a measuring device main body 14 and an optical fiber 15 as a sensor. This optical fiber distributed temperature measuring device utilizes a phenomenon in which the intensity of the backscattered light of the laser pulse light propagating in the optical fiber changes depending on the temperature of the optical fiber, and the temperature around the optical fiber is controlled. It is measured in a distributed manner.

In the LNG vaporizer 1 to be monitored, however, the optical fiber 15 as the sensor is used for all of the outlets of the tubes 4 of the vaporization panel 5 and the appropriate places of the seawater supply path 7, for example, the seawater trough 6. I have installed it. Then, the flow rate control means 12 derives a predetermined seawater flow rate on the basis of all the temperatures on the outlet side of the tube 4 of the vaporization panel 5 and the temperature of the seawater detected by these sensors, and calculates the predetermined seawater flow rate. The controller 12 of the control device 9 is set. The temperature of seawater may be measured by another suitable temperature sensor 16 as indicated by a phantom line in FIG. 1 instead of being measured by the optical fiber distributed temperature measuring device. Further, in the embodiment shown in FIG. 2, the optical fiber 15 is installed by a sheet 17 having a good heat conduction so that the predetermined length portions thereof are collectively brought into contact with the periphery of the outlet side of the tube 4. However, the optical fiber 15
The installation method of is appropriate. Further, the optical fiber 15 can be continuously installed by one to correspond to a plurality of predetermined LNG vaporizers 1, and the number of LNG vaporizers to be measured is large, and one optical fiber 15 is provided for all of them. If it cannot be installed correspondingly, if a plurality of systems are configured through the switch, the common measurement device main body can perform temperature measurement corresponding to all of the large number of LNG vaporizers to be measured.

In the above structure, the seawater flow rate control means 13 is identified by the body 14 of the optical fiber distributed temperature measuring device in correspondence with the distance from the reference position along the optical fiber 15 to the tube 4 of the vaporization panel 5. Measure the temperature of all of the outlets and the temperature of seawater, and their trends, at all times.

When the temperature distribution on the outlet side measured in this way is within a predetermined uniform range, the temperature distribution of the vaporization panel 5 is uniform, and it is considered that the operating state is normal.
In this case, the required amount of seawater is derived from the average value of the measured temperatures on the outlet side and the temperature of seawater, and is set in the controller 12 of the seawater flow rate control device 9. This set value is changed in accordance with the fluctuation of the average value and the temperature of seawater, and by controlling the seawater flow rate control device 9 provided in the seawater supply route 7 with this set value, the minimum necessary value is set throughout the year. The LNG vaporizer 1 can be operated with a flow rate of seawater.

In such an operation, when the temperature on the outlet side of the tube 4 partially falls and the temperature distribution on the outlet side deviates from a predetermined uniform range, the seawater flow rate control means 1
3 derives a required amount of seawater from the minimum value of the temperature measurement values on the outlet side and the temperature of the seawater, and sets it in the controller 12 of the seawater flow rate control device 9. In this way, by controlling the seawater flow rate control device 9 with this set value, seawater of a flow rate corresponding to the portion of the vaporization panel 5 having a shortage of flow rate is supplied, and operation is performed in a direction in which the shortage of flow rate is eliminated.

On the other hand, such a partial decrease in temperature on the outlet side of the tube 4 is considered to be caused by breakage of the water curtain of the seawater in the vaporization panel 5, so the seawater flow rate control means 13
Issues an appropriate alarm. Therefore, the worker receives an alarm from the upper part, can inspect the sprinkling state of the seawater trough 6 of the corresponding LNG vaporizer 1, and can quickly perform a predetermined process.

(Advantages of the Invention) As described above, the present invention reasonably utilizes the optical fiber distributed temperature measuring device to measure all temperatures on the outlet side of the tube of the vaporization panel of the LNG vaporizer to be monitored. However, since the flow rate of the seawater flowing through the seawater supply route is set based on this measured value and the seawater temperature that is appropriately measured, it is possible to operate the LNG vaporizer with the minimum necessary flow rate of seawater throughout the year, and therefore the seawater pump. There is an effect that it is possible to reduce the power consumption for operating the. Further, the present invention, by measuring all the temperature of the outlet side of the tube, it is possible to continuously and automatically monitor the insufficient flow rate of seawater, and early detection and quick countermeasures are possible, There is no problem of individual differences in judgment or oversight,
There is an effect that reliability can be improved.

[Brief description of drawings]

FIG. 1 is a system explanatory view showing the configuration of the present invention, and FIGS. 2 (a) and 2 (b) are enlarged explanatory views of a main part showing an example of an installed state of an optical fiber. Reference numeral 1 ... LNG vaporizer, 2 ... Gas header tube, 3 ...
… Liquid header tube, 4… Tube, 5… Vaporization panel,
6 ... Seawater trough, 7 ... Seawater supply route, 8 ... Seawater pump, 9 ... Seawater flow control device, 10 ... Orifice,
11 ... Flow control valve, 12 ... Controller, 13 ... Seawater flow control means, 14 ... Optical fiber distributed temperature measuring device main body, 15 ... Optical fiber, 16 ... Temperature sensor, 17 ...
… Sheet.

Claims (5)

[Claims] 1. An optical fiber as a sensor of an optical fiber distributed temperature measuring device is installed in the LNG vaporizer to be monitored so as to correspond to all of the outlet sides of the tubes of a vaporization panel, An LNG vaporizer characterized by controlling a seawater flow rate control device provided in a seawater supply path to the LNG vaporizer, based on an average value of temperature measurement values on the outlet side and the temperature of seawater measured by an appropriate temperature sensor. Control method of seawater flow rate 2. An optical fiber serving as a sensor of an optical fiber distributed temperature measuring device, in an LNG vaporizer to be monitored, corresponding to all of the outlet sides of the tubes of the vaporization panel and the proper position of the seawater supply route. The seawater flow rate in the LNG vaporizer, which is installed and controls the seawater flow rate control device provided in the seawater supply path based on the average value of the temperature measurement values on the outlet side of the plurality of tubes and the seawater temperature. Control method 3. The method according to claim 1 or 2, wherein
When the temperature measurement values on the outlet side of the plurality of tubes are non-uniform, the seawater flow rate of the seawater supply path is controlled in accordance with the minimum value of the temperature measurement values on the outlet side.
Seawater flow control method in NG vaporizer 4. The optical fiber according to claim 1 or 2, wherein a sheet having a good thermal conductivity is used to install the predetermined length portions together so as to be in contact with the periphery of the outlet side of the tube.
Seawater flow control method in NG vaporizer 5. The LNG vaporizer according to claim 2, wherein the common optical fiber is installed so as to correspond to all of the outlet sides of the tubes of the vaporization panel and the proper positions of the seawater supply route. Seawater flow control method