JPS59188005A - Power plant using refrigeration of liquefied natural gas - Google Patents

Abstract

PURPOSE:To increase the circulating amount of re-liquefied LNG and the amount of power-generation by storing the natural gas re-liquefied by a re- liquefying device from an expansion turbine one in a receiver tank for circulating the liquefied gas inside the tank to the expansion turbine via a carburetter. CONSTITUTION:The LNG pressurized by a pump 2 is sent to a re-liquefying device 4 for re-liquefying the expanded natural gas from a duct 5 via an expansion turbine 13. In this construction, the LNG with raised temperature is supplied to the expansion turbine 13 via a carburetter 11 to make a job, and then, it is sent to an expansion turbine 17 via a heater 15 to rotate both turbines 13 and 17 to drive a generator 20. The LNG re-liquefied by a re-liquefying device 4 is introduced to a receiver tank 21, and the LNG inside the tank 21 is pressurized by a ciculation pump 8 and supplied to the carburetter 11. The liquid level of the LNG inside the tank 21 is kept constant by controlling an automatic valve 22 in accordance with the output of a liquid level adjusting unit 23.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a liquefied natural gas cold energy power generation facility, in particular, vaporizing liquefied natural gas (hereinafter abbreviated as LNG) using a heat source such as seawater, A part of the natural gas expanded by the expansion turbine is cooled and reliquefied by the above L%G, and after increasing the pressure by a pump, it is vaporized again with the above LAG and a heat source such as seawater, and then circulated to the above expansion turbine. This invention relates to the improvement of liquefied natural gas cold energy power generation equipment equipped with a t-scraping regeneration cycle.

[Background of the invention]

Conventionally, there are power generation facilities that utilize the cold energy of LNG, and those that use LNG's direct expansion method. This type of power generation equipment boosts the pressure of LNG with a pump, vaporizes it in a vaporizer using a heat source such as seawater, and flows it through an expansion turbine, a heater, an expansion turbine, and a heater in this order, and repeatedly generates cold heat. The idea is to vaporize and supply LNG while using it to generate electricity. However, according to this method, although the equipment is simple,
Since the amount of power generated through the use of cold energy is relatively small, in order to increase the amount of power generated, some of the natural gas expanded in an expansion turbine is cooled with LNG and reliquefied, and after being pressurized with a pump, it is mixed with other LNG again? Strain it, vaporize it with a heat source such as seawater, and use the expanded turpin? Some ideas have been proposed to make this circulation more efficient. By using this type P, the company that reliquefies and revaporizes circulating LNG can increase the number of expansion turbines and increase the amount of power generation.

FIG. 1 is a system diagram of an LNG cold energy power generation facility equipped with a general regeneration cycle of this type. In Figure 1, LN
G is pressurized from a conduit 1 to a predetermined pressure by an LN'G pump 2, and then enters a reliquefier 4r from a conduit 3. Here, the natural gas from the conduit 5 is reliquefied, and the LNG whose temperature has increased is sent out from the conduit 6. The LNG reliquefied in the reliquefier 4 passes through a conduit 7, is pressurized by a circulation pump 8, and then passes through an automatic valve 9. It passes through the conduit 10 to the LNG from the conduit 6, and then enters the LNG vaporizer, where it is vaporized from a heat source such as seawater, and enters the expansion tank 1310 through the conduit 12, where the expanded natural gas is It enters a natural gas heater 15 from a conduit 14, is heated by a heat source such as seawater, passes through a conduit 6, enters an expansion turbine 1.7 C, and then enters a natural gas heater 181, where it is heated to room temperature. Natural gas is supplied to the next stage of equipment from conduit 9. A portion of the natural gas expanded in the expansion turbine 13 enters the reliquefier 4 as described above via conduit 5, is reliquefied and enters the LNG vaporizer 11 (along with the LNG from conduit 6), and is then Repeat this cycle. Note that the expansion turbine 1
3.17 is connected to a generator 20r, and the rotation of the expansion turbine 13.17 is recovered as electric power.

In such a regeneration cycle e, from the viewpoint of safe operation of the circulation pump 8, the reliquefaction temperature in the reliquefier 4 is set to a supercooled state V, taking into consideration various operating conditions and control system responsiveness. I am trying to adopt a control method that will make it possible. for example,
As shown in Figure 1, the flow rate of the circulation pump is controlled by an automatic valve 9 so that the temperature of the LNG leaving the reliquefier 4 at the inlet conduit 7 of the circulation pump 80 reaches a predetermined supercooling temperature V. There is. By the way, considering the safety of the circulation pump 8, it is preferable to raise the supercooling temperature, but in this case, if the amount of heat exchanged by the reliquefaction device 4 is constant, increasing the supercooling temperature r In this case, the reliquefaction and ripening per unit flow must be increased, so the number of reliquefiers (circulation amount) must be reduced. This also reduces the turbine wind characteristics and reduces the amount of power generated. From this, the key to making the most of the features of the regeneration cycle is to make the circulation pump 8 safe and to increase the amount of circulation ff1l. However, the conventional LNG cold energy power generation equipment shown in FIG. 1 does not have a configuration that fully satisfies this requirement, and an improvement is desired.

[Purpose of the invention]

The present invention has been made in view of the above ν, and its purpose is to enable safe operation even when the reliquefaction temperature is near the saturation point. The object of the present invention is to provide an FF-type facility for utilizing liquefied natural gas cold energy, which can increase the circulation amount of reliquefied natural gas and increase power generation.

[Summary of the invention]

In the present invention, natural gas from an expansion turbine that has been reliquefied in a reliquefaction device is stored in a receiver tank t, and the liquid level of the liquefied natural gas in the receiver tank is maintained at a certain level. (7) Using a circulation pump, the liquefied natural gas passes through a vaporizer that vaporizes the supplied liquefied natural gas and the re-liquefied natural gas, and then passes through the expansion turbine t.
It is V-shaped to ensure circulation.

[Embodiments of the invention]

The present invention will be explained in detail below using the embodiment shown in FIG.

FIG. 2 is a system diagram showing an embodiment of the power generation equipment of the present invention.
Components that are the same as those in FIG. 1 are designated by the same reference numerals, and their explanation will be omitted here. In FIG. 2, LNG reliquefied by a reliquefaction device 4v trowel is led to a receiver tank 21 from a conduit 7, LNG in the receiver tank 21 is extracted by a circulation pump 8 and pressurized, and the pressurized LNG is Receiver tank 2"
An automatic valve 22° operates according to the liquid level and flow rate of LNG in the pipe 10, and the V strainer is connected to the LNG from the pipe 6 through the pipe 10 and sent to the LNG vaporizer.

Here, in order to maintain the LNG in the receiver tank 21 at a saturation temperature t, the liquid level regulator 23 is installed.If the liquid level changes, the liquid level will be adjusted by the liquid level change signal from the liquid level regulator 23. The automatic valve 22 is adjusted preferentially over the signal 1 from the flow regulator 24 until the predetermined value is returned. Therefore, when it comes to safe operation of the circulation pump 8, even if the LNG in the receiver tank 21 is saturated, the liquid level is controlled to be within a certain range. If you make a plan that satisfies the following, you can secure it without any problems.

According to the embodiment shown in FIG. 2, it is possible to operate in a state where the LNG liquefaction temperature to be reliquefied is around the saturation temperature V, and the reliquefaction temperature is 8 V compared to the conventional case.
By increasing the circulation amount of NG, the air volume of the expansion turbine 13 can be increased, and the amount of power generation can be increased.

In the embodiment shown in FIG. 2, a part of the natural gas from the expansion turbine 13 is reliquefied, but a part of the natural gas from the expansion turbine 17 is It may also be V-strained to reliquefy and the effect is the same.

In addition, there are two expansion turbines with a diameter of 13°17, and two natural gas heaters with a diameter of 15.18.
Even if the number of expansion turbines and heaters is changed depending on the boost pressure of the natural gas, the delivery temperature of the natural gas, the type and characteristics of the expansion turbine, etc., the present invention can be applied and the same effect can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, stable operation can be performed even when the reliquefaction temperature is near the saturation point, so the amount of reliquefied LNG circulated can be increased, and the amount of power generated can be increased. This has the effect of increasing the

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a conventional liquefied natural gas cold energy power generation facility, and FIG. 2 is a system diagram showing an embodiment of the liquefied natural gas cold energy power generation facility of the present invention. 2... LNG pump, 4... Reliquefier, 5,6°7.10... Conduit, 8...
Circulation pump, 11...LNG vaporizer, 13,1
7...Expansion turbine, 15.18...Natural gas heater, 2o...Development electric machine, 21...Receiver tank, 22...Automatic valve, 23・・・・・・
・・Liquid level regulator, 24・・Kuryusha regulator 1 diagram

Claims (1)

[Claims] 1. Part of the natural gas obtained by vaporizing liquefied natural gas and expanding it in an expansion turbine is re-liquefied in a re-liquefier using the liquefied natural gas, and this is vaporized together with the liquefied natural gas in a V-type vaporizer. In the liquefied natural gas cold energy power generation equipment equipped with a regeneration cycle for circulating the liquefied natural gas through the expansion turbine, the natural gas is reliquefied in the reliquefier and the natural gas from the expansion turbine is transferred to a large seaba tank. Because of this,
The liquefied natural gas in the receiver tank is circulated through the expansion turbine via the vaporizer using a circulation pump while the liquid level of the liquefied natural gas in the receiver tank is maintained constant. Liquefied natural gas cold energy power generation equipment.