JPH04316794A - Heating and vaporizing method for low temperature liquefied gas and their equipment - Google Patents

Abstract

PURPOSE:To get a compact equipment and also to easily regulate temperature of low temperature liquefied gas by leading the fluid of the low temperature liquefied gas into the heat exchanger tube arranged in warm water and by blowing out air together with steam into the warm water by means of the ejectors which utilize the steam as a driving source. CONSTITUTION:An warm water tank 1 is filled with warm water 2, for example, of 20 deg.C, and a heat exchanger tube 3 is arranged in the tank 1. LNG is supplied into the heat exchanger tube 3, and vaporized gas G of 0 deg.C and over is extracted. In such an equipment, the ejectors 4 and 5 which utilize steam S as a driving source are provided. Air A in the atmosphere is sucked and compressed by operation of the ejectors 4 and 5, and the air A and the steam S are blown out together from the header 6 arranged at the bottom of the warm water tank 1 for agitating the warm water tank 1 and also as the heat source for heating and evaporating LNG. And, quantity of heat to be supplied to LNG in the heat exchanger tube 3 through the warm water in the warm water tank 1 is controlled by regulating the volume of the steam to be supplied to the ejectors 4 and 5.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is directed to low-temperature liquefied gases whose liquid temperature is below zero, such as liquid Oxygen, liquid nitrogen, liquefied natural gas (
LNG), liquefied petroleum gas (LPG), etc.
The present invention relates to a method and apparatus for heating and vaporizing low-temperature liquefied gas, which safely and reliably supplies vaporized gas and the like.

0002

[Prior Art] Low-temperature liquefied gas, such as LNG and LPG
Our vaporizers safely and reliably raise the temperature of liquefied gas,
Vaporization is an absolute requirement for vaporization equipment. Conventionally, LNG has been heated and vaporized using an open rack vaporizer (hereinafter referred to as ORV) or a submerged combustion vaporizer (hereinafter referred to as SMV).

[0003] The ORV has fins 12 as shown in FIG.
LNG is flowed from below to above in the attached heat exchanger tube 11 as shown by the arrow, and seawater Ws is dropped from above outside the heat exchanger tube 11, and the heat of the seawater Ws is used to heat LNG at, for example, -160℃ to 0℃ or higher. The SMV burns fuel F together with air A in a combustion tube 14 in a water tank 13 as shown in FIG. The high-temperature combustion gas is blown out and comes into direct contact with water W, thereby transferring heat to the heat transfer tube 11 installed in the water tank 13, heating the LNG flowing therein, vaporizing it, and taking it out as vaporized gas G. However, at this time, the combustion gas has the function of stirring the water W in the water tank 13 and increasing the heat transfer coefficient.

As described above, due to the difference in heating sources, ORVs, which have high equipment costs but low operating costs, are used for base load, that is, continuous operation, while SMVs, which have low equipment costs but high operating costs, are used for peak load applications. It is used for demand. However, SMVs require a blower for combustion air, complex control of combustion equipment, etc., safety must be ensured against the use of open flames, and measures against drainage and exhaust gas may be required. .

[0005] Therefore, especially for LNG, it is necessary to develop a vaporizer that has equipment costs comparable to or even cheaper than SMV, that does not have a negative impact on the environment, that can safely and reliably raise the temperature and vaporize instantly when necessary. is requested. In response to such a request, the present applicant has previously proposed, as shown in FIG. We have proposed a device that sucks air A through an ejector 17 and supplies it into the hot water tank 13 as an agitation source (Japanese Unexamined Patent Publication No. 63-163098, hereinafter referred to as the prior invention).

[0006]

The apparatus of FIG. 5 requires two types of ejectors 16 and 17 and a cold water reservoir 18. However, if the amount of steam supplied by the ejector 17 is adjusted, the heat source supply ejector 16 and the cold water reservoir 18 become unnecessary, and the apparatus can be made more compact. That is, an object of the present invention is to provide an improved method and apparatus for the prior invention.

[0007]

[Means for Solving the Problems] A method for heating and vaporizing low-temperature liquefied gas according to the present invention that achieves the above-mentioned objects passes a low-temperature liquefied gas fluid through a heat transfer tube installed in hot water, and uses steam as a driving source. This method is characterized in that air is blown out into the hot water together with steam by an ejector. Furthermore, the low temperature liquefied gas heating/vaporization device of the present invention includes a hot water tank in which a heat transfer tube through which a fluid of low temperature liquefied gas flows is installed in hot water, an ejector for mixing and transporting steam and air, and a mixed gas of the steam and air. It is characterized by being equipped with a header that blows out water into the hot water.

According to the method and apparatus of the present invention,
The ejector can have two functions: supplying steam as a heating source and supplying air for stirring hot water, and the device can be made smaller.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the apparatus of the present invention will be described below with reference to the drawings. In FIG. 1, a hot water tank 1 is filled with hot water 2 at, for example, 20° C., and a heat transfer tube 3 is installed in this hot water. LNG is supplied to the heat exchanger tube 3, and vaporized gas G having a temperature of 0° C. or higher is taken out. In addition, air A in the atmosphere is sucked in and compressed by ejectors 4 and 5 using steam S as a driving source, and the air A and steam S are blown out together from a header 6 installed at the bottom of the hot water tank 1. While stirring in step 1,
Serves as a heat source for NG heating vaporization. That is, the heat possessed by the low-pressure steam S from the ejectors 4 and 5 is transferred through the heat exchanger tube 3 installed in the hot water tank 1 to the LN that passes through the inside of the heat exchanger tube 3.
This is transmitted to G, causing the LNG to heat up and vaporize.

On the other hand, the air A mixed with steam S from the ejectors 4 and 5 has the function of improving the heat transfer coefficient from the hot water 2 to the heat transfer tubes 3 because it violently stirs the hot water 2 in the hot water tank 1. Moreover, it also has the effect of equalizing the temperature of the hot water 2 within the group of heat exchanger tubes 3 in the hot water tank 1. An outline of the ejector 4 is shown in FIG.

Although FIG. 1 shows the case where two ejectors 4 and 5 are provided, the device of the present invention is not limited to this, and can be adjusted according to the required amount of vaporized gas G or the load adjustment range. The number of ejectors to be installed can be determined accordingly. On the other hand, the hot water 2 increased in volume by the steam condensed by applying heat to the heat transfer tube is discharged from the drain port 7.

[0012] Since this waste water is clean condensed water of steam S, it can be sent as is to the pure water production process. In addition, the steam ejector system includes a hot water temperature adjustment mechanism in the hot water tank 1.
(TIC), it is possible to easily maintain the hot water temperature required to prevent freezing in winter and to maintain standby operation even when the vaporizer is stopped.

Next, the operation of the above-described apparatus of the present invention will be described. The hot water tank 1 was filled with hot water at a temperature of 20°C, LNG was supplied to the heat exchanger tube 3 at a rate of 100 T/H, and the vaporized gas G at a temperature of 0°C or higher was taken out. Steam S of 3K or more was supplied to the ejectors 4 and 5 at 16 T/H, respectively. When the pressure of steam S is 7K or more, the number of ejectors in a two-stage configuration as shown in Figure 1 is controlled and the steam pressure (flow rate) at the ejector inlet is controlled.
The control makes it possible to adjust the load in the range of about 30-100 T/H, which can be equivalent to the load adjustment range of SMV. In addition, the amount of water discharged from drain port 7 is 3
It was 2T/H.

[0014]

According to the method and apparatus of the present invention, by adjusting the amount of steam supplied to the steam ejector,
The amount of heat supplied to the low-temperature liquefied gas in the heat transfer tube via the hot water in the hot water tank can be controlled. Further, the amount of air that is simultaneously sucked in and used for stirring the hot water can also be controlled by providing a control valve in the air A suction pipe.

[0015] Therefore, it is possible to select the optimum amount of steam or the number of installed ejectors for vaporizing a predetermined amount of low-temperature liquefied gas. Further, since only the ejector for air suction is used and no ejector for water suction is used, the number of types of ejectors is reduced, and the size of the device can be reduced accordingly.

[0016] Furthermore, the waste water from the equipment is steam condensed water that can be sent to the pure water production process, and the gas discharged is a small amount of steam that is discharged by the steam pressure of air and hot water. Since it is non-polluting and has no negative impact on the environment, it also has no moving parts such as air blowers, making it maintenance-free and extending the life of the equipment. There is an effect that can be expected.

On the other hand, the driving source of the ejector is steam, which cannot be a source of ignition, so the safety of the device is maintained, and the structure is simple, so the device can be made smaller, and its operation is easy. Since it only requires opening and closing of the steam control valve, it has the advantage of being able to easily perform instantaneous operation and rapid load operation, and is also economical because it can effectively use inexpensive low-pressure steam and waste steam from factories, etc. There is also an advantage.

Further, by providing a hot water temperature adjustment mechanism in the hot water tank, it is possible to prevent harmful effects caused by freezing of water. Note that the device of the present invention can be effectively applied as a device for heating vaporization of low-temperature liquefied gas, such as liquefied light hydrocarbons such as liquefied natural gas, liquefied petroleum gas, liquefied ethylene, and liquefied propylene. In particular, it can be effectively applied as equipment for power plants and the like where inexpensive low-pressure steam can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the device of the invention.

FIG. 2 is a schematic diagram of an ejector used in the device of the present invention.

FIG. 3 is an explanatory diagram of main parts of a conventional LNG vaporization device.

FIG. 4 is a schematic diagram of a conventional LNG vaporization device.

FIG. 5 is a schematic diagram of an LNG vaporization device previously proposed by the applicant.

[Explanation of symbols]

Claims (2)

[Claims] 1. Heating of low-temperature liquefied gas, characterized in that the low-temperature liquefied gas fluid is passed through a heat transfer tube installed in hot water, and air is blown out together with the steam into the hot water by an ejector using steam as a driving source.・Vaporization method. 2. A hot water tank in which a heat transfer tube through which a fluid of low-temperature liquefied gas flows is installed in hot water, an ejector for mixing and transporting steam and air, and a header for blowing out the mixed gas of steam and air from the bottom of the hot water tank. A heating/vaporizing device for low-temperature liquefied gas.