JPH045880B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an intermediate medium-filled liquefied gas vaporizer, which vaporizes liquefied natural gas (LNG) or liquefied petroleum gas (LPG) and uses it as a large amount of gas. It is suitable for city gas, electricity fuel, etc.

[Background of the Invention] In recent years, many storage facilities for liquefied natural gas (LNG), for example, are being constructed, and the stored liquefied gas is gasified and supplied as city gas or as fuel for electric power generation facilities. Since such storage facilities are often located on coastal reclaimed land, readily available seawater is used as the heating source for gasification.
It is vaporized by exchanging heat with LNG. Typical types of heat exchangers include open rack vaporizers that directly exchange heat with seawater to gasify it, and vaporizers that burn vaporized LNG in liquid as fuel to produce hot water and use that heat to vaporize it. There are submerged vaporizers, intermediate medium enclosed types that use an intermediate medium to indirectly vaporize LNG using seawater as a heating source, and the present invention relates to an intermediate medium enclosed type liquefied gas vaporizer among these. .

Intermediate-filled liquefied gas vaporizers convert LNG into heat by exchanging heat between LNG and an inexpensive and abundant heat source such as seawater or hot wastewater through an intermediate filling medium with appropriate physical properties (e.g., propane, fluorocarbons, etc.). It evaporates. This method has been adopted because it avoids freezing of seawater, is compact, and is economical.

By the way, if the seawater temperature drops, the temperature of the intermediate encapsulation medium will drop, so unless the LNG supply amount is reduced to an amount proportional to the seawater temperature, the seawater will freeze, making it impossible to vaporize LNG and making it impossible to supply it as fuel. Once they have no choice but to shut off the seawater and the seawater freezes, it takes a very long time for the ice to melt.
In addition, in order to prevent seawater from freezing, LNG is always
Pay attention to the supply amount and seawater temperature, and avoid uneconomical usage methods such as increasing or decreasing the supply amount or operating at low loads.

[Purpose of the invention]

The object of the present invention is to use an intermediate medium enclosed type to prevent seawater from freezing even when the temperature of the seawater decreases, and to ensure the maximum amount of vaporization.

[Summary of the invention]

The present invention detects the temperature or pressure of the intermediate medium in an intermediate medium-filled liquefied gas vaporizer, and controls the detected value so that it does not fall below a set value, thereby achieving stable vaporization before seawater freezes. By maintaining the LNG condition and controlling the amount of LNG vaporized, stable vaporization operation is possible.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In the figure, 1 is a heat exchanger, 2 is a seawater line pipe group, 3 is an LNG line pipe group, 4 is a heater, and 5 is a heat exchanger.
is a flow rate controller, 6 is an automatic valve installed in the LNG conduit 10, 7 is a pressure regulator connected to the heat exchanger 1, and 8 is a pressure regulator connected to the heat exchanger 1.
1 is a selector which receives a pressure signal from the pressure regulator 7 and, when the signal is lower than a set value, sends this lowering signal to the automatic valve 6 with priority over the contact of the flow rate regulator 5; 9 is an intermediate medium; 11 and 12 are Conduits 13 to 17 are conduits for seawater.

LNG to be vaporized enters heat exchanger 1 via conduit 10. Here, an intermediate medium 9 is sealed, and the seawater passes through conduits 13 and 14 to the seawater line tube group 2 of the heat exchanger 1, boils the intermediate medium 9, and causes the conduit 1 to boil.
It is discharged from 5. The intermediate medium 9 boiled by seawater in the heat exchanger 1 contacts the upper LNG line tube group 3 and is condensed again by the LNG refrigerant. With the above operations, heat exchange between seawater and LNG is performed via the intermediate medium 9. In the heat exchanger 1, when the seawater temperature decreases, the temperature of the intermediate medium 9 also decreases. If the temperature of the intermediate medium 9 decreases, there is a risk that the seawater passing through the seawater line pipe group 2 will freeze. From the above, it is necessary to prevent the temperature of the intermediate medium 9 from falling below a certain level, and for this purpose, continuous vaporization becomes possible by reducing the amount of LNG supplied to the heat exchanger 1.

From the above, the pressure of the intermediate medium 9 of the heat exchanger 1 is detected by the pressure regulator 7 in the present invention, because there is a risk that the pressure of the intermediate medium 9 will decrease and the seawater in the seawater line pipe group 2 will freeze. If the detected pressure is below the pressure setting value of the pressure regulator 7, the pressure drop signal is received from the pressure regulator 7 with priority over the signal of the flow rate regulator 5, and the selector 8 automatically selects this signal with priority. The LNG flow rate is reduced to prevent the temperature of the intermediate medium 9 from decreasing, thereby making it possible to continue the LNG vaporization operation.

The LNG vaporized in the heat exchanger 1 is heated in the heater 4 and supplied to the consumer.

In the above embodiment, the pressure of the intermediate medium 9 of the heat exchanger 1 is detected by the pressure regulator 7, but this is because the intermediate medium is saturated, so the pressure regulator is used, which is the main point of the present invention. The purpose of this is to adjust the temperature of the intermediate medium 9, and a temperature controller may be used instead of the pressure controller 7.

〔Effect of the invention〕

According to the present invention, in an intermediate medium-filled liquefied gas vaporizer, by controlling the temperature of the intermediate medium so as not to fall below a certain value (temperature), the temperature of the intermediate medium decreases and the seawater that is the heating source is heated. Freezing can be prevented, thereby allowing continuous vaporization operation. Conversely, when the seawater temperature is high, if the temperature of the intermediate medium is controlled within a range where the seawater does not freeze, the amount of liquefied gas vaporized can be increased within that range, and the capacity of the vaporizer can be fully utilized. There are some effects that can be used.

[Brief explanation of drawings]

The figure is a flow sheet showing one embodiment of the present invention. 1... Heat exchanger, 2... Seawater line pipe group, 3...
...LNG line pipe group, 4... Heater, 5... Flow rate controller, 6... Automatic valve, 7... Pressure regulator, 8...
...Selector, 9...Intermediate medium.

Claims (1)

[Scope of Claims] 1. In an intermediate medium-filled liquefied gas vaporizer equipped with a heat exchanger that vaporizes liquefied gas using an intermediate medium using a heat source for heating, the temperature of the intermediate medium provided in the heat exchanger is Alternatively, if the pressure detection instrument and the intermediate medium temperature or pressure signal detected by the instrument are lower than the set value, priority is given to the signal from the flow controller that regulates the supply flow rate of liquefied gas to the heat exchanger. It is characterized by comprising a selector that outputs a lever reduction signal preferentially to an automatic valve described below, and an automatic valve that controls the supply flow rate of liquefied gas to the heat exchanger based on the output signal from the selector. Intermediate-filled liquefied gas vaporizer.