JPS63233269A - Remote utilizing method of lng cold heat - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for utilizing liquefied natural gas (LNG) cold energy in a remote location.

[Prior art]

LNG is one of the three pillars of primary energy in Japan as an alternative to oil, and its annual consumption is approximately 2.5 billion yen.
It's over 1,000,000 hen. Most of the electricity is used for electricity and city gas. However, since LNG is used as a gas at temperatures above 0°C, -], LNG stored in a tank at 60°C must be
It is heated by evaporation using LNG vaporization equipment. That is, -16
Approximately 207 Kcal/Kg of latent heat plus sensible heat until it becomes a liquid at 0°C or a gas at 60°C can be used as cold energy.

However, due to the cold nature of LNG, the economically usable heat transfer distance is relatively small, making it unusable in remote areas. In other words, if the location is not within several kilometers from the LNG terminal, heat loss and piping costs will be relatively high, and the power cost for returning the LNG will also be high, thus losing economic advantage. In addition, since LNG is flammable, it is necessary to transport LNG in conduits.
There is also a safety issue in the intermediate zone between the NG base and the cold energy use area, and in the end, LNG cold energy use is
It has been limited to cold power generation within the base, or cold heat sources for liquid oxygen, liquid nitrogen, liquid argon, and liquid carbon dioxide production equipment, if there happens to be a user in an adjacent location. However, although there is no problem with the demand for cold energy power generation, there are economic problems, and it is difficult to conveniently locate other cold energy utilization facilities in adjacent areas, so the use of LNG cold energy has not progressed as much as expected. The current situation is that this is not the case.

In other words, most of the potential LNG cold energy is being wasted into the ocean. In particular, even if all of the demand for cold energy in Japan is combined, the existing cold energy utilization facilities cannot even match the amount of NG cold energy generated, so it is necessary to find new sources of demand for cold energy. To this end, it is absolutely necessary to find a way to safely use NG cooling and heating in remote areas.

〔the purpose〕

The present invention has been made in view of the current situation as described below, and the main purpose of the present invention is to enable the use of LNG cold energy to be used safely in remote areas. The purpose of this is to create new demand, that is, new uses, and to secure enough uses to meet the NG cold heat generation area.

〔composition〕

The present invention is a method of utilizing the cold energy of liquefied natural gas, in which an LNG cold heat recovery heat exchanger is installed on the side of the liquefied natural gas vaporization equipment, the air is liquefied by the recovered cold energy, and the resulting liquefied air is This is a method of using LNG cold energy in a remote location, which is characterized by transporting LNG by tank truck or dedicated pipe to a remote usage facility, vaporizing the liquefied air at the remote usage facility, and using the resulting cold energy. .

Figure 1 shows 1. A system diagram of a system in which an NG cold heat recovery heat exchanger is installed and converts air into liquid air using recovered cold heat is shown.

In Fig. 1, raw air flows from intake port l to filter 2.
, it enters the air compressor 3, where it reaches about 2.5, /
It is compressed to aK. Next, it is washed and cooled in a water washing tower 4, and sent to a river tank heat exchanger 10 through a line 5 and a valve 6. Also, this river tank heat exchanger IO
Cold gas is introduced through lines 17 and 20 from the air liquefier 21. This river tank heat exchanger 10
In this step, heat exchange takes place between the introduced feed air and the low temperature gas, where the feed air is cooled to approximately -180° C., which is its liquefaction temperature. This cooled air is passed through valve 11 and line 18 to air liquefaction group 21. Furthermore, through this heat exchange, moisture and carbon dioxide contained in the air are removed by adhering to the tube walls of the heat exchanger.

After a certain period of time has elapsed, low-temperature gas is directly introduced into the flow path a where the raw material air was flowing through the valve 12, and moisture and carbon dioxide adhering there are purged out of the system through the valve 7. During this time, the raw material air flows through a separate line and path and is introduced into the air liquefaction group 21.

The cold gas leaving the river tank heat exchanger 10 is introduced into a heat exchanger 27 where it is cooled by a heat exchanger between it and the LNG introduced through line 31 before being compressed in a compressor 28 to approximately Boosted to 50kg#JG. This pressurized gas is 1. , NG heat exchanger 29 cools the gas to about -140° C., and the cold heat accompanying the evaporation of L and NG is sufficiently transferred to the low-temperature gas. This sufficiently cooled low-humidity gas is then circulated to the air liquefaction unit 21 via the expansion valve 25.

The cold gas passing through the expansion valve further lowers its temperature due to the Joule-1 Hemson effect and liquefies the cooling air in the air liquefaction group 21. Note that the low-temperature gas passing through the line 17 described above is a gas that is almost in equilibrium with the liquefied air, and contains 9% nitrogen.
Contains more than 1 part.

The liquefied air remaining at the bottom of the air liquefaction unit 21 is stored in a liquefied air tank 24 via a filter 23 by a pump 22. The liquefied air tank 24 has a temperature of -190°C and a pressure of 0.
．． The liquefied air stored here is maintained at approximately normal pressure of 0.5 kg/ciG and is sent to remote locations by tanker truck or the like depending on demand.

Note that air can be liquefied with a lower pressure gas by using an expander instead of the expansion valve 25, but the selection is within the skill of those skilled in the art.

LNG enters from line 13 at approximately -160°C, and after cooling the gas sufficiently in LNG heat exchangers 27 and 29 provided on the suction and discharge sides of the circulating gas compressor, most of the gas evaporates and flows into line 32. Exit the system. At this time, the low-temperature gas and LNG will directly exchange heat, but the low-temperature gas is rich in nitrogen gas as mentioned above, and the LNG (
The flammability limit for methane (mostly methane) is also narrow at 5 to 1 part.
Even in the event of a leak, the danger can be avoided by providing a device to detect the C114 concentration in the low temperature gas.

In the following manner, LNG cold energy is converted into cold energy as liquefied air.

The liquefied air obtained as described above contains LNG cold energy, and is transported from the tank 24 on the LNG base side to a remote location by a tank truck or the like. In this case, the tank truck is kept cold, but during this transportation time, a small amount of it evaporates due to heat loss, so it is sealed up to the tank's pressure resistance, but if it exceeds it, a mechanism is set in place to release it to the outside air using a release valve. do. However, since the released gas has a composition similar to that of air, there is no danger in releasing it as is, and the tank has the advantage of being able to be opened to the atmosphere and requiring only a normal pressure tank.

The liquefied air transported by the tank truck to the cold energy consumer side is once received into the liquefied air receiving tank 40 shown in FIG. 2, and then distributed to the respective demand equipment. Second
In the example of the ultra-low temperature warehouse 41 shown in the figure, pipes with spray nozzles 42 are installed on the ceiling, and temperature control valves 4
3, the liquefied air from line 44 is boiled and evaporated into the warehouse to cool the interior of the warehouse. By controlling the valve 43, the temperature can be adjusted between -50 and 100 degrees depending on the contents.
Can be kept at ℃. The vaporized air is purged from the movable looper 45 to the outside of the warehouse. Since the movable looper 45 is equipped with a pressure regulator, the pressure inside the warehouse is maintained at a slight pressure. Moreover, this purge air can also be used as air for air curtains provided for entering and exiting the warehouse.

In addition to being transported by tanker trucks, liquefied air may also be transported by pump directly through pipes, etc. if the demand points are relatively close together or if a new industrial complex is being formed in a remote location.

Since the liquefied air receiving tank 40 is normally open to atmospheric pressure, 0.3 to 0.6% of the liquefied air is lost to evaporation per day with normal cold storage, but the supply from the tank truck and the load on the demand side must be carefully adjusted. Tobacco losses are kept to a minimum.

The method of the present invention is also particularly effective in food cryopreservation techniques. Liquefied air boils and evaporates at -190°C under atmospheric pressure, so 48% of the food that comes into contact with it evaporates.
It absorbs the latent heat of vaporization of Kca Q /kg and becomes low-temperature air, and this air is generally heated to -20°C, so if the specific heat is simply set to 0.25 kca Q /kg °C, the sensible heat of 44 Kca Q /kg is obtained. I also have to take
In total, food can be frozen with a total amount of heat of 92 Kca Q /kg. For example, food with a thickness of 1 to 3 cm is 1
When freezing 1 kg of food, which is rapidly frozen in 0 to 15 minutes, when spraying with a liquefied air spray freezing device at a pressure of 0.35 kg/cdG, the required amount of liquefied air is 0.8 to 1
．． It weighs about 2 kg.

Furthermore, according to the method of the present invention, a large amount of cold energy can be obtained at low cost, so that it can be used for, for example, sports where artificial snow is made or for leisure purposes.

〔effect〕

According to the method of the invention, liquefied air can be produced in quantities corresponding to at least 50% of vaporized LNG, so that in the near future approximately 1.5 million tons of liquefied air can be supplied per year. This is a total of 1 for oxygen and nitrogen in 1982.
This is almost the same as the production volume of 1.8 billion Nrri'.

With the prospect of such a huge supply, it is possible to create a market of its own.

For one, by creating a network of liquefied air service stations throughout the country, the liquefied air obtained by the method of the present invention can be used as a cold source for refrigerated vehicles. For example, a 6- to 8-ton refrigerator truck has a 3.75KIN refrigerator, but the method of the present invention does not require such an expensive machine, but simply installs piping on the ceiling of the vehicle and liquefies it with a spray nozzle. It is sufficient to spray 5 to 1.5 kg/H of air, and the equipment cost is reduced to 11 J. The liquefied air cylinder loaded in such a car costs approximately 100 km for 10 hours of driving.
F, capacity is sufficient, and as an on-vehicle tank, a maximum of 1.20Q is sufficient, so there is no particular practical problem. The liquefied air that evaporates inside the car needs to be exhausted outside the car, but before that, some of it can be guided into the driver's seat to air-condition the driver's seat.

An advantage of the present invention is that the use of LNG cold energy can be made according to time variations during use.

Conventional cold energy utilization has been a fixed and constant usage, so if it is to match the usage pattern of a thermal power plant, for example, the number of LNG fuels used must be kept within a small flow rate range. This star is generally 20-30%, so in reality only a small portion of the potential company is available. However, in the present invention, cold energy is replaced with liquefied air and stored, so during the daytime, for example, liquefied air is generated depending on the power generation site, and at night, for example, -
It is also possible not to create liquefied air. The liquefied air manufacturing process of the present invention is a process that mainly involves only a compressor, as shown in Figure 1, so meteor control of this device is extremely easy, and since it is handled with air, it is abnormal. Sometimes it can be easily released out of the system. You can also drive with great peace of mind.

Another advantage of the present invention is that there are very few locational restrictions. As mentioned above, there is an extremely large demand for liquefied air, and its uses are nearly limitless as long as economic efficiency allows. Since such excellent cold energy can be produced in one corner of an LNG terminal, thermal power plants and city gas production plants that use LNG will have new valuable products.

In terms of economics, compared to producing normal liquefied nitrogen or oxygen, it is thought that LNG can be supplied at a price of about 173 yen at present, considering the use of cold energy and the fact that air separation is not required. However, it is expected that the number will increase to 174 to 115 if further technological development and distribution network improvements are made.

Comparing the method of the present invention with conventional methods that use refrigerants such as chlorofluorocarbons, it is estimated that the present invention is currently more economical on a calorific basis, especially for demands that require ultra-low temperatures below -40°C. .

Furthermore, one of the advantages of the present invention is that it has excellent safety = 11-. In order to make maximum use of LNG cooling energy, the object to be cooled must be 1. directly immersed in NG, or
It would be possible to use a method of spraying NG, but since LNG is flammable and forms an explosive mixture with air, this is completely impossible.

However, in the present invention, since the object to be cooled is air, the cooling method with the highest efficiency described in item 1 can be carried out as a matter of course, and the range of applications is greatly expanded. For example, the method of the present invention can be used to excavate a tunnel, and the construction can be carried out with the spring area completely frozen. Since it is air that evaporates at this time, it does not pose any danger to personnel such as oxygen deprivation even in interior spaces such as tunnels, and on the contrary, it is completely safe as it is equivalent to replenishing fresh air.

Also, environmentally, the present invention provides extremely superior cooling and heat utilization. Most of the current cooling and heating systems use chlorine-containing or fluorine-containing organic compounds such as fluorocarbons as refrigerants. Even widespread technologies such as air conditioning are no exception. However, although such refrigerants are safe in themselves, in the long run they leak out of the system and diffuse into the atmosphere. Scholars have suggested that such refrigerants block radiation from the sun or suppress radiation from the earth, nitriding the earth. In the present invention, since the air itself provides cold heat, whether it is brought into direct contact with the object to be cooled or indirectly cooled with a heat exchanger, there is no physical impact on the environment. There isn't.

[Brief explanation of drawings]

Figure 1 shows a system diagram of a system in which an NG cold heat recovery heat exchanger is installed on the LNG vaporization equipment side and converts air into liquefied air using the recovered cold heat, and Figure 2 shows a system for a liquefied air vaporization system in a remote location. Show the diagram. 3...Air compressor, 4...Air cleaner, 10...
Reversing heat exchanger, 21... Air liquefaction tower, 24...
...Liquefied air tank, 28...Low temperature gas compressor, 27
．． 29... LNG heat exchanger, 40... Liquefied air receiving tank, 41... Ultra-low temperature warehouse, 42... Spray nozzle. (1 other person)

Claims (2)

[Claims] (1) In a method that utilizes the cold energy of liquefied natural gas, a liquefied natural gas cold energy recovery heat exchanger is installed on the side of the liquefied natural gas vaporization equipment, and the recovered cold energy liquefies air, and the resulting liquefied air A method for using LNG cold energy in a remote location, which is characterized by vaporizing LNG in a remote location and using the cold energy. (2) Ultra-low-temperature warehouses, ultra-low-temperature laboratories, artificial snow-making equipment, where cooling equipment used in remote locations directly evaporates liquid air;
The method according to claim 1, which is a food freezing device, a soil improvement method facility, an automatic freezing bundle, a low-temperature grinding facility, or an ice skating rink facility.