JP3547169B2 - Liquefied gas supply equipment - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a liquefied gas supply system, and more particularly to a liquefied gas supply system suitable for storing, transporting, and supplying a cryogenic liquid fuel such as liquefied natural gas (LNG).
[0002]
[Prior art]
FIG. 12 shows the concept of a liquefied gas supply facility in a conventional LNG terminal or the like. The semi-underground tank 1 stores liquid LNG unloaded from an LNG transport ship. In the tank 1, a primary (first-stage) pump 2 is provided submerged in the liquid, and the liquid LNG is pumped to the ground surface by the pump 2. A part of the pumped LNG (liquid) is gasified by the vaporizer 6 and sent out as fuel for the boiler or gas turbine in the base. Here, the vaporizer 6 allows seawater and waste heat to flow in from its inlet 6A and flows out from an outlet 6B, and performs heat exchange during this to gasify liquid LNG. Most of the LNG (liquid) pumped by the pump 2 is pressurized by the secondary (second stage) pump 3 and remains in a liquid state at another LNG terminal by the pipeline 9 by the pipeline 9. After being pressurized, it is heated and gasified by a heat exchanger (not shown), and is pumped to a demand area for power generation gas or city gas.
[0003]
[Problems to be solved by the invention]
In such a liquefied gas supply system, demand for LNG, which is a clean energy source from the viewpoint of environmental protection, increases, and the service area expands, thereby increasing the capacity and scale of the equipment and increasing the handling pressure. ing. For this reason, the secondary pump 3, which is the main pump for pressurizing and feeding LNG, is increasing its handling flow rate, head, and consequently drive horsepower. For this reason, the motor for driving the pump 3 is also about several hundreds to several thousand kW, requiring high-voltage and large-capacity power supply equipment, and the power transmission and distribution equipment for supplying power to the motor has to be large. In addition, the increase in the number of pump stages and the increase in size thereof are also causing problems in equipment space and maintenance. In addition, the LNG is transported to a remote power station, and the power generated by the LNG at the power station is drawn into a pump for pressurizing and pumping the LNG at the LNG terminal via a long transmission and distribution line from the power station. Power must be supplied to the motor to rotate the pump. For this reason, from the viewpoint of energy saving, supply of power to the pump for pressurizing and pumping LNG requires transportation loss until the LNG is sent as gas or liquid to the power plant, loss of power generation efficiency at the power plant, and transmission of power. Inevitably, a loss in the distribution line, a loss when the motor is driven to rotate, and the like are inevitably involved. On the other hand, it is not preferable to consume a large amount of electric power in the course of environmental cleaning.
[0004]
The present invention has been made in view of the problems of the related art, and has as its object to provide a self-contained liquefied gas supply facility that does not require external energy supply.
[0005]
[Means for Solving the Problems]
The liquefied gas supply equipment of the present invention is a liquefied gas storage tank, a first-stage pump submerged in the storage tank, a second-stage pump that pressurizes and sends the liquid discharged from the first-stage pump, A heat exchanger that heats a part of the liquid discharged from the second-stage pump to form a high-pressure gas, and supplies a high-pressure gas supplied from the heat exchanger to expand and reduce the pressure of the gas. wherein an expansion turbine for driving a second stage pump, Ri Do from the previous SL piping system for the connected feeding the outlet of the second stage pump, the heat of the discharge liquid in the first stage pump It is characterized by comprising a piping system for heating through an exchanger to produce high-pressure gas, supplying the gas to the expansion turbine, and starting the second-stage pump .
[0006]
Further, the heat exchanger comprises a burner, preferably Rukoto with a connection pipe to be burned in at least a part of the burner of the gas discharged from the exhaust port of the expansion turbine, also of the first stage pump It is preferable that a piping system for heating the discharged liquid through the heat exchanger to generate high-pressure gas and supply the gas to the expansion turbine to start the second-stage pump is provided with a check valve.
[0007]
Further, in the method for starting the liquefied gas supply equipment according to the present invention, the discharge port of the first-stage pump is connected to an air supply port of the expansion turbine via a heat exchanger to discharge the first-stage pump. The second stage pump is started by gasifying the liquid and supplying the gas to the expansion turbine.
[0008]
[Action]
Since the heat exchanger that heats a part of the liquid discharged from the second-stage pump and gasifies the liquid by high pressure is provided, a part of the self-liquid pressurized by the second-stage pump can be gasified at high pressure. Then, the high-pressure gas supplied from the heat exchanger is supplied to the expansion turbine to expand and reduce the pressure of the gas, whereby the impeller of the expansion turbine can be driven to rotate. Since the main shaft of the expansion turbine is directly connected to the main shaft of the second stage pump, the pump can be rotationally driven by the liquid itself pressurized by the second stage pump. That is, it is possible to configure a self-contained liquefied gas pressurized pumping system that does not require supply of energy from the outside.
[0009]
Since the heat exchanger has a burner and at least a part of the gas discharged from the exhaust port of the expansion turbine is provided with a connection pipe that is burned by the burner, high heat is applied to the liquid pressurized by the second-stage pump. And supply it to the expansion turbine as a high-temperature, high-pressure gas. Since the fuel of the burner is the liquefied gas itself discharged from the exhaust port of the expansion turbine, a high-temperature and high-pressure gas can be produced by its own liquid. With such a configuration, the output of the expansion turbine can be increased or the size of the expansion turbine can be reduced, which is one step ahead of the above-described configuration from the viewpoint of energy saving.
[0010]
Further, since the discharge port of the first-stage pump is connected to the pipe connected to the air supply port of the expansion turbine via the heat exchanger, even when the second-stage (secondary) pump is not rotating, High-pressure gas can be supplied to the supply port of the expansion turbine. Since the second-stage pump is a self-contained pump, once stopped, gas is not supplied to the supply port of the expansion turbine, and the pump itself cannot be restarted. For this reason, the high-pressure gas can be supplied to the supply port of the expansion turbine by the above-described connection pipe, so that the self-contained pump can be easily started.
[0011]
【Example】
Hereinafter, first and second embodiments of the present invention will be described with reference to the accompanying drawings. The same reference numerals in the drawings indicate the same or corresponding parts.
[0012]
FIG. 1 shows a configuration of a liquefied gas supply facility according to a first embodiment of the present invention. In the figure, solid arrows indicate liquid flows, and dotted arrows indicate gas flows. A liquefied gas (liquid) such as LNG is stored in a semi-underground tank 1 and the liquid is pumped to the surface by a primary pump 2 submerged in the liquid. The secondary pump 3 that pressurizes the liquid discharged from the primary pump 2 and feeds the liquid to the pipeline 9 has an expansion turbine 5 and a main shaft connected thereto, and the pump 3 is driven by the turbine 5 . In addition, the expansion turbine 5 and the pump 3 may have one common main shaft, and may be an integrated turbine driven pump in which each is sealed. A part of the liquid discharged from the pump 3 is connected to the vaporizer 6 and the heat exchanger 7 by piping, and the outlet of the heat exchanger 7 is connected to the supply port of the expansion turbine 5 by piping. That is, one discharge port of the pump 3 is connected to the supply port of the turbine 5 through the valve V ₂ , the carburetor 6, and the heat exchanger 7. Further, the exhaust port of the turbine 5 is connected to a gas delivery pipe 8 through a heat exchanger 7. A pipe L ₂ provided with a valve V ₁ is connected to an outlet of the primary pump 2 at an inlet of the vaporizer 6. Further, the inlet of the vaporizer 6 is connected through a pipe L ₃ from the discharge port of the pump 3 via a valve V _2.
[0013]
Next, the operation of the liquefied gas supply equipment of the present embodiment will be described.
FIG. 6 is a pressure / enthalpy diagram illustrating the thermodynamic states S ₁ , S _2, etc. of the liquefied gas in each part of the liquefied gas supply equipment shown in FIG. In Figure 1, like stored in semi-underground tanks 1 liquid LNG is supersaturated S ₁ of the pressure P ₀ in the vicinity near atmospheric pressure. Then, pressurized to a pressure _{P 1} on the primary pump, a state _{S 1.} Then, be taken into account losses by secondary (second stage) pump 3 is pressurized to polytropic manner the pressure P _3, extracts a part of the liquid wkg it became state P _3, vaporized through a valve V ₂ It flows into the vessel 6. Liquid wkg state _{S 3} receives the heat from the vaporizer 6 and the heat exchanger 7 (enthalpy _{i 3} → _i 4), only the heat exchanger loss goes to a low state _{S 4} of the pressure. At the outlet of the heat exchanger 7, the liquid in the state S ₃ at the discharge port of the pump 3 becomes high-pressure gas in the state S ₄ and is pushed through the supply port 5 of the expansion turbine 5. Then, the polytropic expansion in the turbine 5 from the state S ₄ to the state S ₅ which is shifted entropy constant line by a turbine loss. With this expansion, the impeller of the turbine 5 is rotated, and the impeller of the pump 3 directly connected to the main shaft of the turbine 5 is rotationally driven. At the exhaust port of the turbine 5, the gas is reduced in pressure to P ₅ , radiates heat in the heat exchanger 7 and is sent out to the pipeline 8. This gas may be delivered for power generation at a predetermined pressure, or for city gas, or may be used as fuel for turbines or boilers in LNG terminals. On the other hand, the pump 3 to the sucked once state S ₃ to the pressurized part wkg is extracted residual liquid (W-w) kg is in the state S _1, is re-pressurized further by a pump 3, a state S ₂ becomes , From the pipeline 9 to another LNG terminal or the like as a high-pressure liquid.
[0014]
That is, the combination of the pump 3, the expansion turbine 5, and the heat exchangers 6, 7 makes use of the difference in gradient between the isentropic line in the supersaturated liquid range and the isentropic line in the overheated state as shown in FIG. Thus, the expansion turbine can be driven. This means that the enthalpies of the states S ₁ , S ₂ , S ₃ , S ₄ , and S ₅ are i ₁ , i ₂ , i ₃ , i ₄ , and i ₅ , respectively, and the total inflow amount of the pump is Wkg and the extraction amount is wkg. When
W (i ₃ −i ₁ ) + (W−w) (i ₂ −i ₃ ) ≦ w (i ₄ −i ₁ )
Then, it is established as a system. That is, by appropriately selecting the pressurizing pressure P ₃ of the pump 3 and the amount of heat (enthalpy i ₃ → i ₄ ) to be applied by the heat exchanger so that this system is established, a self-contained external power ( It is possible to perform a pump operation using self-liquid that does not require supply of energy).
[0015]
FIG. 2 shows a liquid flow and a gas flow when the pump is activated. Since the pump 3 is a self-contained pump operated by its own liquid, it cannot be automatically restarted once stopped. Therefore, from the pipe L ₂ to open the valve V ₁ was at startup from the air supply opening to 汲 viewed raised liquid in the primary pump 2 to the vaporizer 6, a turbine 5 and high pressure gasification gives heat through the heat exchanger 7 Push in. Then, discharging was expanded in the turbine 5 by vacuum to drive the pump 3 gas to the outside by opening the valve V _5. Therefore, the pump 3 is activated by gasifying the liquid pumped by the primary pump 2 and supplying the gas to the turbine 5. As the rotational speed of the expansion turbine 5 gradually increases, pressing pressure of the secondary pump 3 gradually increases, the discharge fluid in the secondary pump 3 through valve V ₂ of the pipe L _3, is introduced into a vaporizer 6, normal Driving state.
[0016]
FIG. 3 shows a liquid flow and a gas flow during a steady operation. Activated secondary pump 3 was rises pressure gradually rotated up, downstream check valve (not shown) of the valve V ₁ is gradually closed gradually. Thus, the liquid of the total amount Wkg the flow of the liquid pumped by the primary pump 2 enters the suction port of the pump 3, of which, is extracted in a state S ₃ which wkg is pressurized, the remainder (W-w) The kg is re-pressurized, and is pressurized and sent to the pipeline 9 as a liquid in the state S ₂ of the pressure P ₂ . The extracted liquid wkg is provided with heat by a vaporizer 6 and a heat exchanger 7, gasified, expanded in a turbine 5 and rotationally driven by a pump 3, and decompressed. Delivered as gas. In the heat exchanger 7, the exhaust gas of the turbine 5 imparts heat to the supply gas. As a control method of the rotation speed of the pump 3, a rotation speed detector is attached to the shaft of the pump 3, the rotation speed of the pump shaft is measured, and the heating temperature of the vaporizer 6 or the heat exchanger 7, It can be performed by controlling the flow rate, the temperature of the waste heat source, the flow rate, the discharge pressure of the secondary pump, the flow rate, and the like.
[0017]
FIG. 4 shows the liquid and gas flows when the turbine / pump is closed. Even when the secondary pump 3 and the expansion turbine 5 are stopped for maintenance or the like, it is necessary to continue sending fuel to utilities such as a boiler and a turbine in the LNG terminal. During stoppage of such a turbine / pump, closes the valve V ₂ of the pipe L _2, by opening the valve V ₆ of the bypass pipe, the liquid pumped by the primary pump as shown in the figure, the carburetor 6 , A valve V ₆ , and gasification through a heat exchanger 7 to supply a fuel gas from a pipeline 8.
[0018]
FIG. 5 shows a control system of the liquefied gas supply facility. The rotation sensor 11 is a rotation detector that detects the number of rotations of the shaft of the expansion turbine 5 or the pump 3. The detected rotational speed information are is sent to the controller 12, controls the opening of such valves V _2, V _7. The opening / closing control (open: O, closed: C) in the startup, steady operation, and rotation speed control states of these valves is as shown in the table in the figure. Speed control, the adjustment of the extraction amount wkg by adjusting the opening of the valve V _2, applied heat due to seawater adjustment of the opening degree of the valve V ₇ of warming fluid such as to the vaporizer 6 (i ₃ → i ₄₎ Or the amount of waste heat flowing into the vaporizer ₈ can be adjusted by adjusting the valve V8 to adjust the amount of heat applied (i ₃ → i ₄ ).
[0019]
7 to 11 show a liquefied gas supply facility according to a second embodiment of the present invention. The second embodiment has the same basic configuration as the first embodiment, except that the heat exchanger 7 in the first embodiment is replaced with a combustion heater 17 to reduce the amount of gas discharged from the expansion turbine 5. In this case, the air supply gas is actively heated by burning the section. That is, the combustion heater 17 to provide an amount of heat to the supply air gas turbine 5 as shown in FIG. 7 is provided with a burner, comprising a pipe L ₄ branching from the pipe L ₅ connected to an exhaust port of the expansion turbine 5, The inflow amount is adjusted by the valve V ₄ , and the fuel is burned by the burner in the combustion heater 17. Therefore, by heating the supply gas to the expansion turbine 5 with the combustion heater 17, the temperature and pressure can be further increased. For this reason, the output of the expansion turbine 5 increases, and the output of the pump 3 can be further increased. Further, if the output is fixed, the shapes of the turbine 5 and the pump 3 can be further reduced. Part of the gas decompressed by the work performed by the expansion turbine 5 is burned in the heating combustor 17, so that the gas is self-contained.
[0020]
FIG. 8 shows the flow of liquid and the flow of gas at the time of startup of the second embodiment, and corresponds to FIG. 2 of the first embodiment. FIG. 9 shows the flow of liquid and the flow of gas during steady operation of the second embodiment, and corresponds to FIG. 3 of the first embodiment. FIG. 10 shows the flow of liquid and the flow of gas when the pump / turbine of the second embodiment is stopped, and corresponds to FIG. 4 of the first embodiment. FIG. 11 is an explanatory diagram of the control system of the second embodiment, and corresponds to FIG. 5 of the first embodiment. In the present embodiment, it relates largely to the adjustment of the opening degree adjustment is imparted heat amount of the valve V ₄ for adjusting the flow rate of the gas flowing into the heating burner 17, plays an important role in regulating the output of the turbine / pump.
[0021]
In each embodiment described above, an example has been described in which feed applied pressure was pressurized state S ₂ in the secondary pump liquid as it is to the outside, pressure is converted into the gaseous state through a vaporizer You may make it pressure-feed. Also, an example has been described in which wkg is extracted from the liquid Wkg by the secondary pump and gasified, and the remaining (W−w) kg is repressurized and sent. The remaining wkg may be gasified by pressurizing and feeding the remaining wkg. Thus, various modified embodiments are possible without departing from the gist of the present invention.
[0022]
【The invention's effect】
As described above, according to the liquefied gas supply equipment of the present invention, when the liquefied gas is pumped under pressure, it is not necessary to externally supply electric power or other fuel to drive the pump. With such a self-contained system, a system with extremely low energy loss is realized, and power transmission and distribution equipment is not required. Therefore, the size of the liquefied gas supply facility can be reduced, that is, the area of the liquefied gas supply base can be reduced, and it is possible to contribute to clean and beautify the environment. In addition, a large amount of liquefied gas such as LNG can be pumped under pressure, which contributes to energy saving and, consequently, the preservation of the global environment.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a configuration of a liquefied gas supply facility according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a flow of a liquid and a flow of a gas at the time of startup in the facility.
FIG. 3 is an explanatory diagram showing a flow of a liquid and a flow of a gas in a steady state in the facility.
FIG. 4 is an explanatory diagram showing a flow of liquid and a flow of gas when the pump / turbine is stopped in the facility.
FIG. 5 is an explanatory diagram of a control system in the facility.
FIG. 6 is a pressure-enthalpy diagram showing a thermodynamic state of a liquefied gas.
FIG. 7 is an explanatory diagram showing a configuration of a liquefied gas supply facility according to a second embodiment of the present invention.
FIG. 8 is an explanatory diagram showing a flow of a liquid and a flow of a gas at the time of startup in the facility.
FIG. 9 is an explanatory diagram showing a liquid flow and a gas flow in a steady state in the facility.
FIG. 10 is an explanatory diagram showing a flow of liquid and a flow of gas when the pump / turbine is stopped in the facility.
FIG. 11 is an explanatory diagram of a control system in the facility.
FIG. 12 is an explanatory diagram showing a configuration of a conventional liquefied gas supply facility.
[Explanation of symbols]
Reference Signs List 1 semi-underground tank 2 primary (first stage) pump 3 secondary (second stage) pump 5 expansion turbine 6 carburetor 7 heat exchanger 8 gas pipeline (delivery pipe)
9 liquid pipeline (delivery pipe)
17 Heated combustor

Claims (3)

A liquefied gas storage tank, a first-stage pump submerged in the storage tank, a second-stage pump for pressurizing and sending the discharge liquid of the first-stage pump, and a discharge liquid of the second-stage pump A heat exchanger for heating a part of the gas to produce a high-pressure gas, and an expansion for supplying the high-pressure gas supplied from the heat exchanger and expanding and reducing the pressure of the gas to drive the second-stage pump. a turbine, Ri Do and a piping system for the connected feeding before Symbol outlet of the second stage pump,
A liquefied gas supply comprising a piping system for heating the discharge liquid of the first-stage pump through the heat exchanger to gasify the high-pressure gas, supplying the high-pressure gas to the expansion turbine, and starting the second-stage pump. Facility. The discharge system of the first-stage pump is heated through the heat exchanger to high-pressure gas, and supplied to the expansion turbine to start the second-stage pump. The liquefied gas supply facility according to claim 1, wherein A liquefied gas storage tank, a first-stage pump submerged in the storage tank, a second-stage pump for pressurizing and sending the discharge liquid of the first-stage pump, and a discharge liquid of the second-stage pump A heat exchanger for heating a part of the gas to produce a high-pressure gas, and an expansion for supplying the high-pressure gas supplied from the heat exchanger and expanding and reducing the pressure of the gas to drive the second-stage pump. A turbine and a piping system for sending liquid connected to a discharge port of the second stage pump,
A discharge port of the first-stage pump is connected to a supply port of the expansion turbine via a heat exchanger, and gas discharged from the first-stage pump is gasified and supplied to the expansion turbine. Starting the to that liquefied gas supply installation, characterized in that to start the second stage pump by.

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