JPH0616229Y2 - Decompression boiler type vaporizer - Google Patents

Description

[Detailed Description of the Invention] Industrial Field of Use This invention relates to a liquefied natural gas (hereinafter referred to as LNG) vaporizer, which uses steam generated in a depressurized can to generate heat in a heat transfer tube.
The present invention relates to a decompression boiler type carburetor that prevents boiling vibration and unnecessary temperature rise at a low load by using steam from a high-pressure boiler as a steam generation heat source of a decompression boiler when heating LNG to vaporize it.

BACKGROUND ART As an LNG vaporizer, an open rack vaporizer has been put into practical use, which uses seawater as a heat medium to sprinkle water on a panel-shaped heat transfer tube that is vertically arranged to vaporize LNG at elevated temperatures.

Also, as a vaporizer using burner combustion heat as a heat source,
There is an underwater combustion type.

This is because the high-temperature combustion gas generated by the underwater combustion burner is guided below the heat exchanger for vaporizing LNG immersed in the water tank and ejected into the water, and the temperature of the LNG is raised and vaporized using water as an intermediate heat medium. Become.

In such an underwater combustion method, due to the influence of moisture in the water tank,
Burner ignition failure is likely to occur, and the heat exchanger structure is complicated and expensive in order to cope with a severe circulating water flow,
Further, there is a problem that the capacity of the blower and the electric motor becomes excessive in order to generate and maintain the circulating water flow.

In addition, a decompression boiler is put into practical use as a device that uses burner combustion heat (Japanese Patent Publication No. 52-47083, Japanese Patent Laid-Open No. 62-245003,
Japanese Examined Japanese Patent Publication No. 62-2667).

As shown in FIG. 2, this is a depressurized can body that contains water (2) as a heat medium and has a predetermined depressurized atmosphere inside the can body.
(1) and a burner (3) installed at the bottom of the can body where water has accumulated
Burner tube (4) for transferring the combustion heat of
Comprised of heat transfer tubes (5) arranged in the upper space of (1),
The water (2) heated by the burner tube (4) boils under reduced pressure to generate steam, and the heat transfer tube is generated by the condensation heat transfer of this steam.
It has the effect of raising the temperature of the fluid in (5) and is often used as a hot water boiler for water supply and heating.

Therefore, as an LNG vaporizer, instead of the underwater combustion type,
By applying a decompression boiler, the influence of moisture can be eliminated, the burner ignitability is improved, and unlike the underwater combustion type,
It is considered that the discharge pressure corresponding to the head of the aquarium drops.

Further, it is considered that the heat exchanger structure is simplified and the cost is reduced, the capacity of the blower and the electric motor is reduced, and the cost is reduced.

Problems of the Prior Art Therefore, the inventors have made various studies to apply the pressure reducing boiler to the LNG vaporizer.

However, in the depressurization boiler, when the steam temperature and pressure in the can drop, boiling vibration and noise are generated due to bubble rupture, so the operating temperature is usually restricted, that is, about 60 ° C. is the lower limit.

Therefore, when the decompression boiler is used as a vaporizer of LNG, the vaporized natural gas (hereinafter referred to as NG) rises to the operating temperature in the can as the load becomes low.

On the other hand, the vaporized gas line should be kept at room temperature, that is, above 20 ℃.
Since it is not necessary to raise the temperature of NG, raising the temperature to such a lower limit temperature of operation is a waste of energy, and it is necessary to attach a heat insulating facility to the line for safety measures such as preventing burns.

Purpose of the invention This invention, when applied to the LNG vaporizer of the pressure reducing boiler,
An object of the present invention is to provide a decompression boiler type carburetor for LNG having a configuration capable of preventing boiling vibration due to low load and unnecessary temperature rise of NG.

Outline of the Invention In this invention, a burner pipe that transfers the combustion heat of a combustion burner is arranged in the lower part of a closed and high-pressure can body, water is retained in the lower part of the can body including the same part, and the upper space of the can body is The steam generated in the high-pressure boiler is introduced into the high-pressure boiler that has become a steam chamber and the lower part of the closed and decompressed can, and heat is transferred to the water that has accumulated in the lower part of the can, and the condensed water after heat transfer is transferred to the high-pressure boiler. In order to maintain the vaporized gas temperature to be kept constant, it consists of a steam circulation system piping for returning, the upper space inside the can becomes a steam chamber, and a decompression boiler with a bundle of heat transfer tubes through which liquefied natural gas flows. A decompression boiler type carburetor having means for controlling a fuel control valve of a burner according to the vapor temperature of the decompression boiler and the vaporized gas temperature derived therefrom.

DISCLOSURE BASED ON DRAWING OF THE INVENTION FIG. 1 is a circuit diagram showing the structure of a decompression boiler type carburetor according to this invention.

In the drawings, the heated fluid pipe is shown as a single pipe for easy understanding, but the present invention can use any known single pipe or bundle of pipes.

The decompression boiler type carburetor shown in FIG. 1 is composed of a high pressure boiler (10) and a decompression boiler (20) which are connected by piping.

The high-pressure boiler (10) contains water (2) as a heat medium in the can body, and a burner tube for transferring the combustion heat of the burner (11) to the water at the bottom of the can body where water has accumulated. (12) is provided, and the upper part of the can is a steam chamber.

It should be noted that the burner tube (12) may have any known structure such as an exhaust gas reversal type in which combustion gas makes a U-turn.

The decompression boiler (20), which is composed of a closed can separate from the high-pressure boiler (10), stores water (2a) as a heat medium in the can,
In addition, a vacuum pump (not shown) is connected and arranged in order to create an atmosphere at a predetermined atmospheric pressure or less inside the can.

The decompression boiler (20) has an inlet pipe section (15) for introducing steam generated in the steam chamber of the high pressure boiler (10), and a heat transfer tube section (16) for transferring steam heat to water retained in the lower part of the can body. ), And a steam circulation system pipe constituted of a concentrated water return pipe part (17) for returning condensed water after heat transfer to the high-pressure boiler (10).

In addition, LNG of the fluid to be heated is stored in the upper chamber of the decompression boiler (20).
A heat transfer tube (30) through which heat flows is arranged.

The heat transfer pipe (30) is connected to the LNG supply pipe (6) through the control valve (31) and heats and evaporates the LNG in the pipe with the steam generated in the room. Flow through tube (32).

Further, the fuel system of the burner (11) of the high pressure boiler (10) is provided with a fuel control valve (14), and a thermometer (13) and a decompression boiler (20) arranged in the steam chamber of the high pressure boiler (10). Thermometer (21) for measuring the steam temperature inside, and outlet pipe outside the can of the decompression boiler (20)
To adjust the opening of the fuel control valve (14) and adjust the combustion state of the burner (11) according to each measurement value of the thermometer (33) that measures the temperature of NG passing through (32) The control system of is provided.

In this configuration, the combustion heat of the burner (11) heats the water (2) through the burner pipe (12), and the generated steam is transferred to the decompression boiler (20) through the steam introduction pipe section (15). Introduced into the heat pipe section (16), further heating the water (2a) in the decompression boiler (20),
Due to the condensation heat transfer of steam generated under reduced pressure, the heat transfer tube (3
It has the effect of raising the temperature of LNG in 0).

The temperature and pressure of the steam chamber of the decompression boiler (20) are appropriately adjusted to a lower limit of about 60 ° C. by controlling the combustion of the burner (11) of the high pressure boiler (10) according to the LNG load.

Here, the control system mainly uses high pressure according to the steam temperature so that the NG temperature passing through the outlet pipe (32) and the steam temperature in the decompression boiler (20) do not exceed the boiling temperature of water under atmospheric pressure. The opening / closing degree of the fuel control valve (14) of the boiler (10) is controlled, the amount of steam generated in the high pressure boiler (10) is adjusted, and the NG temperature is kept constant.

If the pressure difference is large and the gravity head cannot be used, it may be returned by a pump.

With the above configuration and control, the NG outlet temperature can be controlled to be constant during vaporization of LNG, and boiling vibrations that occur in the low pressure region of the pressure reducing boiler, for example, 0.07 kg / cm ² abs, 40 ° C can be prevented. .

Therefore, the NG temperature becomes constant regardless of LNG load fluctuations.

With the configuration of the present invention, when the decompression boiler is applied to the vaporizer for LNG, boiling vibration and unnecessary temperature rise of NG, which are problems at low load, are suppressed, and fuel loss is reduced.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing the structure of a decompression boiler type vaporizer according to the present invention. FIG. 2 is a circuit explanatory diagram showing a configuration of a conventional pressure reducing boiler. 1,20 …… Decompression boiler section, 2,2a …… Water, 3,11 …… Burner, 4,12 …… Burner tube, 5,30 …… Heat transfer tube, 6 …… LNG
Supply pipe, 10 ... High-pressure boiler, 13,21,33 ... Thermometer, 14 ...
… Fuel control valve, 15 …… Steam introduction pipe part, 16 …… Heat transfer pipe part,
17 …… Condensed water return pipe section, 31 …… Control valve, 32 …… Outlet pipe.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Creator Nobuhiko Tsui 15-10 Miyamatsu-cho, Hiratsuka-shi, Kanagawa 320-10 Tokyo Gas Apart 320 (72) Creator: Yoji Sato 2-6, Nishi-Nagasumoto-dori, Amagasaki-shi, Hyogo Sumitomo Precision Industries Co., Ltd. (72) Inventor Hitotani Shoya 2-6 Nishi-Nansuhondori, Amagasaki-shi, Hyogo Sumitomo Precision Industries Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. A hermetically sealed and high-pressure can body is provided with a burner tube for transferring heat of combustion of a combustion burner in a lower part thereof, water is retained in a lower part of the can body including the same, and an upper space of the can body is a steam chamber. The steam generated in the high-pressure boiler is introduced into the closed high-pressure boiler and the lower part of the closed and decompressed can, and the heat is transferred to the water accumulated in the lower part of the can, and the condensed water after heat transfer is returned to the high-pressure boiler. It consists of a decompression boiler equipped with a circulation pipe, the upper space inside the can becomes a steam chamber, and a bundle of heat transfer tubes through which liquefied natural gas flows. A decompression boiler type carburetor comprising means for controlling a fuel control valve of a burner according to a steam temperature of a boiler and a vaporized gas temperature derived from the boiler.