JPS6256399B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an evaporative supply method for vaporizing and sending liquefied gas. More specifically, the present invention relates to a method for evaporating and supplying liquefied gas that can always take out gas under uniform conditions without causing large fluctuations in the temperature and pressure of the gas to be supplied, as well as in the supply amount.

<Conventional technology> Conventional evaporative supply of liquefied gas involves sending the liquefied gas as a liquid from a storage tank to an evaporator, and then supplying the vaporized gas there as is, or if necessary, temporarily supplying the vaporized gas to a gas holder. A method is used to store it and then supply it.

<Problems to be solved by the invention> However, the amount of evaporated gas used at the consumption site is usually not constant, and in order to absorb the accompanying load fluctuations, a large capacity gas holder is generally installed. are doing. In addition, a temporary storage tank is installed before sending the liquefied gas to the evaporator to minimize load fluctuations, but in many cases low-temperature liquefied gas is sent directly to the evaporator, This causes various problems such as local bumping, condensation of the gas, vibrations associated with this, and uneven temperature of the liquefied gas in the storage tank.

<Means for Solving the Problems> As a means to solve these drawbacks, the inventors formed a circulation system between the storage tank and the evaporator, and also caused a certain amount of liquefied gas and evaporated gas to coexist in the storage tank. Furthermore, by using the evaporated gas to preheat the liquefied gas to be supplied and absorbing load fluctuations by the latent heat of vaporization of the liquefied gas, a large-capacity gas holder unlike the conventional one is not required, and a homogeneous gas can be produced. We have developed a new liquefied gas evaporation supply method that can supply the required amount of liquefied gas at any time.

That is, the method for evaporating and supplying liquefied gas of the present invention includes (a) providing a storage tank and an evaporator, transporting the liquefied gas from the bottom of the storage tank to the evaporator, and transporting the liquefied gas containing the evaporated gas from the evaporator to the inside of the storage tank. (b) a mixing distributor is provided in the gas phase in the storage tank; , the liquefied gas supplied to the storage tank and the liquefied gas containing evaporated gas from the evaporator are introduced into the storage tank through mixing in the mixing distributor, and at this time, the supplied liquefied gas is freed from evaporated gas before being introduced into the storage tank. (c) Detects the pressure of the evaporated gas to control the flow rate of the heat medium in the evaporator, and It is characterized by controlling the liquid level, pressure, and temperature in the storage tank to be kept constant by detecting the liquid level and controlling the supply flow rate of liquefied gas.

<Actions and Effects> An example of a device for carrying out the method of the present invention is
It mainly consists of a so-called storage tank and an evaporator. The storage tank and the evaporator are connected by a liquefied gas transport pipe that transports the liquefied gas from the bottom of the storage tank to the evaporator, and a liquefied gas transport pipe that transports the evaporated gas-containing liquefied gas generated in the evaporator back to the storage tank. , thus forming the circulatory system. In the storage tank, the evaporated gas forms a gas phase and the liquefied gas forms a liquid phase, and the two phases coexist to achieve vapor-liquid equilibrium. Therefore, when the pressure in the storage tank decreases due to the supply of evaporated gas, the liquefied gas in the storage tank evaporates to compensate for the pressure drop, and thus the pressure fluctuations in the storage tank are absorbed into the liquid phase as latent heat of vaporization. Alternatively, the load fluctuation can be absorbed by diffusing from the liquid phase to the gas phase.

If the newly delivered liquefied gas is directly fed into the liquefied gas in the storage tank, undesirable phenomena such as bumping will occur as described above. The liquid is mixed with the heated liquefied gas to adjust the liquid temperature and ensure smooth supply. The liquefied gas is preheated indirectly using the evaporated gas in the storage tank as a preheating source. Specifically, the liquefied gas supply pipe may be guided to the upper part of the storage tank and passed therethrough. Furthermore, the liquefied gas introduced into the mixing and distribution device is mixed with the heated liquefied gas, and the temperature of the supplied liquefied gas is raised based on the pressure in the storage tank and the temperature in the mixing and distribution device.
In this way, the supplied liquefied gas undergoes two stages of temperature adjustment and is stored in the lower part of the storage tank, so that the liquefied gas is supplied extremely smoothly.

Furthermore, the method of the present invention is characterized in that both the amount of liquefied gas supplied into the storage tank and the amount of gas evaporated in the evaporator are automatically controlled. The amount of liquid in the storage tank is always maintained at a constant level by opening and closing the supply valve based on the signal detected by the liquid level detector. When the liquid level falls below a predetermined value, the valve opens and the supply of liquefied gas into the storage tank begins, and when the liquid level reaches the upper limit, the valve closes and the supply of liquefied gas is temporarily interrupted. In addition, the amount of evaporated gas is determined by detecting the load fluctuation due to the usage amount as a pressure change in the piping while the gas extracted from the evaporative gas outlet of the storage tank is supplied to the usage location, and based on this signal, the evaporator heats up. This is done by adjusting the flow rate of the medium. Also, during use, since the pressure at the upper part of the storage tank changes, the change in internal pressure is detected at the same time and the flow rate of the heat medium is adjusted.

The evaporator is constantly supplied with liquid liquefied gas from the bottom of the storage tank, but while the upper part of the storage tank is filled with gas and a predetermined internal pressure is maintained, there is no movement of the heat medium in the evaporator, so no evaporation occurs. Not done. When the gas starts to be used, a signal that captures changes in the gas supply pipe and storage tank internal pressure opens the heat medium circulation valve, heat exchange with the heat medium begins, evaporation of the liquefied gas occurs, and the gas is used. Continuous throughout. When the gas is no longer used and the gas supply pipe and storage tank internal pressure are restored, the heat medium circulation valve is closed again and evaporation is stopped. When the gas is used and evaporated, the liquefied gas is consumed by evaporation, the liquid level in the storage tank decreases, and the above-mentioned supply of liquefied gas begins in parallel. As described above, the liquefied gas evaporation supply device according to the present invention can be installed on-site where gas is used and can efficiently supply gas.

Further, when the evaporated gas is used, the internal pressure of the storage tank changes, and the temperature of the gas changes accordingly.
Therefore, in order to maintain the gas flow rate adjustment accuracy due to temperature changes, a control instrument can be provided and corrected as necessary.

The material of the device according to the present invention is not particularly limited, but on the low temperature side, a material that is resistant to cold brittle fracture must be used.

<Example> Next, an example of a device according to the present invention will be described with reference to the drawings. The liquefied gas sent from the pipe 1 is flow controlled by the control valve 2, passes through the pipe 3, and is transferred to the storage tank 7.
will be introduced in The liquefied gas is preheated by a preheating device 4 located above the storage tank 7. Generally, the preheating device 4 is heated by heat exchange with gas in a storage tank. The preheated liquefied gas is further fed into the mixing/distributing device 6 in the storage tank 7 . A heated liquefied gas containing vaporized gas from the evaporator 9 is separately introduced into the mixing/distributing device 6 through a pipe 11, and both are mixed and distributed into the storage tank.

On the other hand, the liquefied gas extracted from the bottom of the storage tank 7 via the pipe 8 is heated by the evaporator 9, becomes a liquefied gas containing evaporated gas, and is sent to the mixing/distributing device 6 of the storage tank 7 via the pipe 11.

In this way, the evaporated gas is stored in the upper part and the liquefied gas is stored in the lower part in the storage tank 7. The gas used is taken off via lines 13, 14 and 15.

The amount of liquefied gas in the storage tank 7 is controlled by opening and closing the control valve 2 by the liquid level control device 17. When using evaporated gas, pressure changes due to load fluctuations are detected by the control device 21, and the flow rate is adjusted by the control device 20 by opening and closing the control valve 16.
In addition, the signal captured by the control device 21 is transmitted to the control device 19.
The amount of heat medium in the evaporator 9 is adjusted by opening and closing the control valve 10.

In the figure, reference numerals 22 and 23 indicate an example of a method of detecting changes in temperature and pressure due to the use of evaporative gas and controlling the amount of gas to be used by regulating the regulating valve 16.

[Brief explanation of the drawing]

The figure shows an example of the apparatus of the present invention in a flow sheet format. 4... Liquefied gas preheating device, 6... Mixing distribution device, 7... Liquefied gas storage tank, 8... Liquefied gas transport pipe, 9... Evaporation device, 11... Liquefied gas transport pipe containing evaporated gas.

Claims (1)

[Claims] 1. A liquefied gas evaporative supply method for always supplying evaporated gas under constant conditions regardless of load fluctuations, including: (a) providing a storage tank and an evaporator, and supplying liquefied gas from the bottom of the storage tank to the evaporator; The liquefied gas containing the evaporated gas is transported from the evaporator to the inside of the storage tank, thus forming a circulation system, and the liquid phase consisting of the liquefied gas and the gas phase consisting of the evaporation gas are separated in the storage tank. (b) A mixing distributor is provided in the gas phase in the storage tank, and the liquefied gas supplied to the storage tank and the liquefied gas containing evaporated gas from the evaporator are introduced into the storage tank through mixing in the mixing distributor. At this time, the supplied liquefied gas is indirectly preheated using the evaporated gas as a preheating source before being introduced into the storage tank, while the evaporated gas is taken out from the upper part of the storage tank and supplied to the outside, and (c) the pressure of the evaporated gas is The liquid level, pressure, and temperature in the storage tank are kept constant by detecting the temperature and controlling the flow rate of the heat medium in the evaporator, and by detecting the liquid level in the storage tank and controlling the supply flow rate of liquefied gas. A liquefied gas evaporation supply method characterized by controlling the liquefied gas.