JPH05231595A - Vapor phase combined heating pressure reducing device for liquefied gas evaporator - Google Patents

Abstract

PURPOSE:To increase energy efficiency and improve durability of components such as vaporization cylinder and backpressure valve in a vapor phase combined heating pressure reducing system. CONSTITUTION:A backpressure valve 4a is provided in a liquid phase line 2 and set in such a way that it is opened at the predetermined pressure or less. When pressure in a liquefied gas container 1 is higher than the set pressure of the backpressure valve 4a, gas is pressure-reduced and supplied from a vapor phase line 3 by a vapor phase line pressure regulating valve 9a. When pressure in the container 1 is lower than the set pressure of the backpressure valve 4a, gas is vaporized by a vaporization cylinder 5, gas pressure is reduced by a liquid phase line pressure regulating valve 8, and gas can be also supplied by the liquid phase line 2. When inlet pressure of the vapor phase line pressure regulating valve 9a is below the set pressure of the back pressure valve 4a, the vapor phase line pressure regulating valve 9a is controled to set outlet pressure of the vapor phase line pressure line regulating valve 9a to higher pressure than the set pressure of liquid phase pressure regulating valve 8 so that the vapor phase line pressure regulating valve 9a is operated at all times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor phase combined heating and depressurization system for a liquefied gas evaporator, and in particular a vapor phase combined heating and decompression suitable for reducing the pressure rise of an LP gas consumption type evaporator. Regarding the device.

[0002]

2. Description of the Related Art Regarding equipment for vaporizing and supplying liquefied gas such as an LP gas consumption type evaporator, regardless of the gas quality, environment, conditions, etc., for example, the outlet pressure is always 10 kgf /
It is necessary to suppress the pressure rise, for example, by setting the pressure to be less than cm ^2, and therefore, several methods such as a reduced pressure heating method have been devised. Among them is the vapor phase combined heating and depressurization method,
The system is generally a system that supplies gas from either the gas phase or the liquid phase according to the pressure change in the container filled with the liquefied gas.

FIG. 7 shows an example of a conventional heating and depressurizing system using a gas phase together. In the figure, 1 is a liquefied gas storage container, and a liquid phase line 2 and a gas phase line 3 are inserted through the container 1. The liquid phase line 2 captures the gas liquid stagnating in the container 1, and the gas phase line 3 captures the vaporized gas filling the upper part of the container 1. The liquid phase line 2 is piped toward the inside of the vaporization cylinder 5 via a back pressure valve 4a serving as an opening / closing valve 4 and a check valve 4b. A heat medium 6 is filled in the vaporization cylinder 5,
Further, a heat source 7 for heating the heat medium 6 is provided. As a result, the gas liquid passing through the vaporization cylinder 5 is heated by the heat medium 6
It is heated and vaporized. The liquid phase line 2 that has bent and passed through the vaporization cylinder 5 is connected to the gas outlet side via a pressure adjusting valve 8 of the liquid phase line.

On the other hand, the gas phase line 3 joins the liquid phase line 2 at the outlet side of the pressure adjusting valve 8 of the liquid phase line via the pressure adjusting valve 9 of the gas phase line, and communicates with the gas outlet side. Has been done.

In the above apparatus, the back pressure valve 4a at the inlet of the vaporizing cylinder 5 has a container pressure set to a set pressure (for example, 10 kgf / c).
m ² ) Open in the following cases. Further, the pressure adjusting valve 8 of the liquid phase line is set to a higher value than the pressure adjusting valve 9 of the gas phase line.

The gas supply by the above system is performed as follows. That is, first, the pressure of the container is the back pressure valve 4a.
When the pressure is higher than the set pressure of, the back pressure valve 4a is closed, the vaporization cylinder 5 does not function, and the gas exclusively passes through the gas phase line 3 and through the pressure adjusting valve 9 of the gas phase line (gas outlet side (gas Consumer side).

Next, when the supply of the gas from the vapor phase line 3 continues, the evaporation of the liquid is promoted in the container 1 and the latent heat of evaporation is removed from the liquid, so that the liquid temperature is lowered and the pressure in the container 1 is increased. descend. When the pressure drop in the container 1 becomes equal to or less than the set pressure of the back pressure valve 4a, the back pressure valve 4a opens and liquid enters the vaporization cylinder 5, and the pressure adjusting valve 8 of the liquid phase line opens to open the liquid phase line 2 Gas is supplied from. Since the pressure adjusting valve 8 of the liquid phase line has a higher set pressure than the pressure adjusting valve 9 of the gas phase line, the pressure adjusting valve 9 of the gas phase line should be closed when the pressure adjusting valve 8 of the liquid phase line is opened. Then, the supply of gas from the vapor phase line 3 is stopped.

Then, the container 1 is heated by heat absorption from the outside.
When the internal liquid temperature rises, the back pressure valve 4a is closed, and the gas supply by the gas phase line 3 is restarted.

FIG. 8 shows changes with time in the pressure inside the container 1 and the vaporization cylinder 5 and the opening / closing of the back pressure valve 4a during the system operation.

[0010]

SUMMARY OF THE INVENTION The above conventional vapor phase heating and depressurizing system is used in the liquid phase line 2 or the vapor phase line 3.
Since the gas is supplied from only one of the two, the entire amount of the gas to be supplied must be generated in the vaporization cylinder 5 while the liquid phase line 2 is operating, and therefore, in order to vaporize the liquid. However, there is a problem that the energy efficiency is poor because much heat is required.

Further, as shown in FIG. 8, the internal pressure of the vaporizing cylinder 5 frequently and drastically fluctuates, so that the vaporizing cylinder 5 is easily damaged, and the back pressure valve 4a repeats opening and closing, especially at the time of starting, so that the useful life is shortened. There was a problem that it became shorter and more likely to break down.

An object of the present invention is to improve the conventional gas phase combined heating and depressurizing system to enhance the energy efficiency in gas supply and to improve the durability of components such as a vaporizing cylinder and a back pressure valve. ..

[0013]

Means for Solving the Problems The inventors changed the idea of supplying gas only from either the liquid phase line or the gas phase line in the conventional gas phase combined heating and depressurization system, and We have reached the finding that a new gas-phase combined heating and depressurization method that constantly maintains gas supply in the gas-phase line regardless of the internal pressure is effective in solving the above problems.

According to the configuration of the present invention based on the above knowledge, the gas phase line and the liquid phase line are inserted into the liquefied gas storage container, and the liquid phase line is opened when the inside of the container drops below a set pressure. After passing through the vaporizing cylinder filled with the heat medium via the on-off valve, the gas outlet is controlled through the liquid pressure line pressure control valve that controls the valve opening to adjust the outlet pressure to the set pressure. A pressure control valve of the gas phase line for controlling the valve opening so as to adjust the outlet pressure according to the pressure difference between the inlet and the outlet, in the gas phase line, A pressure adjusting valve for the gas phase line is provided in which the outlet pressure is set higher than the set pressure of the pressure adjusting valve for the liquid phase line, and the pressure of the gas phase line is adjusted by the pressure adjusting valve of the gas phase line and the liquid phase line. Front on each outlet side with regulator valve Formed by the confluence in the liquid phase line.

That is, in the prior art, in order to select the liquid phase line or the gas phase line to supply the gas, the opening and closing of the gas phase line pressure adjusting valve is controlled according to the inlet side pressure, and the liquid phase line is controlled. The set value of the pressure control valve was adjusted to be higher than the set value of the vapor phase line pressure control valve. On the other hand, the present invention contemplates and adopts a new gas-phase combined heating and depressurization method in which the gas-phase line is constantly operated and the liquid-phase line is preliminarily used. The opening and closing shall be controlled according to the inlet side pressure and the outlet side pressure, and the set value of the outlet pressure of the vapor phase line pressure adjusting valve shall be higher than the set value of the liquid phase line pressure adjusting valve when the opening and closing valve is opened. Is characterized by.

For the above adjustment, the vapor phase line pressure regulating valve according to the present invention has a primary chamber communicating with the inlet side of the vapor phase line and a secondary chamber communicating with the outlet side of the vapor phase line, The primary chamber and the secondary chamber are separated by a diaphragm,
The diaphragm is biased toward the primary chamber by the elastic means, and one end of the valve body that is movable in the biasing direction or the opposite direction is connected to the diaphragm, and the other end of the valve body is the gas outlet of the primary chamber. It is configured so that it can be fitted with the valve seat provided on the.

Furthermore, in order to suppress the fluctuation of the outlet pressure of the vapor phase line pressure regulating valve and obtain a stable gas supply pressure,
The present invention also improves the gas-phase line pressure regulating valve, that is, the primary chamber communicating with the inlet side of the gas-phase line and the secondary chamber communicating with the outlet side of the gas-phase line having a larger cross-sectional area than the primary chamber. A secondary chamber is provided, and a diaphragm that is biased toward the primary chamber and a pressing means that is connected to the diaphragm and protrudes into the primary chamber are provided in the secondary chamber, and the secondary chamber is movable in the biasing direction or the opposite direction. One end of the piston is fitted in the primary chamber so as to be able to contact the pressing means, and the other end of the piston is provided with a valve body that can be fitted in the valve seat provided in the gas outlet of the primary chamber. A pressure regulating valve for a vapor phase line is provided.

[0018]

According to the above construction, when the pressure in the container is higher than the set pressure of the back pressure valve, the back pressure valve is closed, the vaporization cylinder does not function, and the gas passes exclusively through the gas phase line and the pressure in the gas phase line. It is supplied to the gas outlet side (gas consuming side) via a regulating valve.

When the gas is continuously supplied from the gas phase line, the evaporation of the liquid is promoted in the container, and the latent heat of evaporation is removed from the liquid, so that the liquid temperature is lowered and the pressure in the container 1 is lowered.
When the pressure drop in the container falls below the set pressure of the back pressure valve, the back pressure valve opens and liquid enters the vaporizing cylinder. In that case, the outlet pressure of the liquid phase line pressure control valve is lower than the set pressure of the gas phase line pressure control valve, so the liquid phase line pressure control valve remains closed and no gas is supplied. Gas supply continues only from. Therefore, the pressure in the container further decreases, and thus the outlet pressure of the vapor phase line pressure regulating valve becomes equal to the outlet pressure of the liquid phase line pressure regulating valve.

At that time, the liquid phase line pressure adjusting valve is opened and the gas vaporized by the vaporizing cylinder is supplied to the gas outlet side (gas consuming side). At the same time, the gas line pressure control valve remains open, so gas is also supplied from the gas line. When the liquid temperature lowering continues, the container pressure also lowers, so that the outlet pressure of the pressure regulating valve of the vapor phase line lowers, that is, the gas amount from the vapor phase line pressure regulating valve decreases. When the gas supply amount in the vapor phase line decreases, the evaporation amount in the container also decreases, and the latent heat of vaporization also decreases. This process continues until the latent heat of vaporization of the liquid in the container and the amount of heat absorbed by the container from the outside or the like equilibrate, and becomes stable at the time of equilibrium.
After stabilization, gas is supplied at a constant ratio from both the vapor phase line and the liquid phase line.

Next, according to the structure of the vapor phase line pressure regulating valve according to the second aspect, the areas of the diaphragms in contact with the primary chamber and the secondary chamber are equal, and the difference between the inlet pressure and the outlet pressure is the deformation of the diaphragm. That is, it is directly reflected in the opening and closing of the valve body. Since the diaphragm is pushed toward the primary chamber by the elastic means, the pressure in the secondary chamber required for stabilizing the diaphragm is reduced by an amount corresponding to the amount of pressing by the elastic means. When the inlet pressure becomes large, the valve body will be largely opened, but the amount of gas also increases accordingly and the pressure in the secondary chamber also becomes large, so the valve body tends to close. That is, the opening / closing degree of the valve body is adjusted depending on the pressing amount of the elastic means.

Further, according to the structure of the pressure adjusting valve of the vapor phase line according to the third aspect, in addition to the pressing amount by the elastic means, the pressure load of the secondary chamber is proportional to the ratio of the area of the diaphragm and the area of the tip of the piston. Is further reduced. Therefore, the amount of outlet pressure for countering the inlet pressure is reduced, and the fluctuation of the outlet pressure is reduced regardless of the fluctuation of the inlet pressure.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. The same members as those described above are designated by the same reference numerals and the description thereof will be omitted.

FIG. 1 shows a system of a gas phase combined heating / depressurizing system according to an embodiment of the present invention. The outline of the present embodiment will be described with reference to the same drawing. An opening / closing valve 4 provided in a liquid phase line 2 is shown in FIG.
Has a back pressure valve 4a interposed in the line, one end of the check valve 4b is connected to the downstream side of the back pressure valve 4a, and the other end is connected to the back pressure valve 4a. Reference numeral 9a denotes a pressure adjusting valve of the gas phase line, and the set value of the outlet pressure of the pressure adjusting valve 9a is set higher than the set value of the pressure adjusting valve 8 of the liquid phase line when the back pressure valve 4a is opened.

Back pressure valve 4a, pressure adjusting valve 8, pressure adjusting valve 9
Regarding the setting of a, in a preferred example, when the set pressure of the back pressure valve 4a is 6 kgf / cm ² and the set pressure of the pressure adjusting valve 8 is 0.6 kgf / cm ² , the inlet pressure setting in the pressure adjusting valve 9a is set. It is the value P ₁ = 6kgf / cm ² to the outlet pressure set value P ^₂ = 1.5kgf / cm _2.

According to the above construction, the pressure inside the container is controlled by the on-off valve 4.
The gas is supplied exclusively from the gas phase line 3 until the outlet pressure of the pressure control valve 8 and the outlet pressure of the pressure control valve 9a become equal to each other from the time when the pressure is higher than the set pressure of, and thereafter, the gas phase line 3 and the liquid phase are supplied. It will be supplied from line 2.

FIG. 2 shows the structure of the pressure adjusting valve 9a for the vapor phase line. In FIG. 2, the inside of the pressure adjusting valve 9a for the vapor phase line is connected to the inlet side of the vapor phase line 2 by a diaphragm 10a. A chamber 11a and a secondary chamber 12a communicating with the outlet side are formed. The diaphragm 10a can be deformed to either side of the primary chamber 11a and the secondary chamber 12a, and the diaphragm 10a is biased toward the primary chamber 11a by a spring 13a as an elastic means. The valve body 14a is movable in the urging direction or the opposite direction, one end thereof is connected to the diaphragm 10a in the primary chamber 11a, and the other end thereof is connected to a gas outlet 15a provided outside the primary chamber 11a. It is arranged so that it can be fitted with the valve seat 16a.

In the above structure, the set value of the pressure adjusting valve 9a on the vapor phase line can be obtained as follows.

That is, the inlet pressure P ₁ is 5 kgf / cm ² and the outlet pressure P _{2 is} the set point of the pressure regulating valve 9a.
Is selected as 0.5 kgf / cm ² , 5A = 0.5A + Sp ……………………………… (1) However, A: Area of diaphragm 10a Sp: Spring 13a at set point
From the force (1) that urges the diaphragm 10a. Sp = 4.5A ……………………………… (1) If Sp is constant, the relationship between P ₁ and P ₂ is shown in Table 1. , Fig. 6
become that way.

[0030]

[Table 1]

Thus, according to this embodiment, the back pressure valve 4a
₂ is set so that the set value of the outlet pressure P ₂ of the pressure adjusting valve 9a of the gas phase line at the time of opening is higher than that of the pressure adjusting valve 8 of the liquid phase line.
As shown in Table 1, the inlet pressure P ₁ and the outlet pressure P ₂ of the pressure adjusting valve 9a of the vapor phase line are set as shown in Table 1. Therefore, gas is always supplied from the vapor phase line 3 during the operation of the apparatus. Therefore, the efficiency of energy required for the vaporization cylinder 5 and the like in the conventional vapor phase combined heating and depressurization method is improved, and further comparison between FIG. 3 and FIG.
The frequency of opening and closing the back pressure valve 4a becomes low, so that the back pressure valve 4a,
It is possible to solve the problem of deterioration of the durability of the vaporizing cylinder 5.

Next, another embodiment of the present invention will be described. This embodiment has been made in view of the problem that occurs in the vapor phase line pressure regulating valve 9a, and the technical problems in the vapor phase line pressure regulating valve 9a will be described below.

That is, in the gas-phase line pressure regulating valve 9a, the relationship between the inlet pressure P ₁ and the outlet pressure P ₂ is a linear curve with the gradient shown by the curve A in FIG. Outlet pressure P ₂ from the curve depends on the fluctuation of the inlet pressure P _1, as the amount of fluctuation of P ₁ is large, it is understood that the fluctuation amount of the outlet pressure P ₂ increases. Therefore, the gas supply pressure changes depending on the state of the inlet pressure P ₁ , and the supply pressure becomes unstable during system operation over time. A curve A in FIG. 5 shows the change over time in the fluctuation of the gas supply pressure during the system operation.

In order to solve such a problem, in the present embodiment, in the system of FIG. 1, the pressure adjusting valve 9a of the vapor phase line is used.
Is replaced with a pressure regulating valve 9b shown in FIG. Also in this embodiment, the entire system is shown in FIG.
Therefore, the description of the same contents as those described above with reference to FIG. 1 will be omitted.

In FIG. 4, the vapor line pressure adjusting valve 9b
Is a primary chamber 11b communicating with the inlet side of the vapor phase line 2,
It has a secondary chamber 12b communicating with the outlet side of the vapor phase line 2. The difference from the above-mentioned embodiment is that the primary chamber 11b and the secondary chamber 12b are formed separately, and the secondary chamber 12
The axial sectional area of b is substantially larger than the axial sectional area of the primary chamber 11b.

A diaphragm 10b is provided in the secondary chamber 12b.
And the diaphragm 10b is urged toward the primary chamber 11b by a spring 13b. As in the above, the diaphragm 10b can be deformed on either side of the primary chamber 11b and the secondary chamber 12b.
A pressing rod 17b is connected to the diaphragm 10b and projects into the primary chamber 11b. In the primary chamber 11b, a piston 18b movable in the biasing direction or the opposite direction is provided.
Is arranged, and one end of the piston 18b is fitted into the inner wall of the primary chamber 11b and can come into contact with the tip of the pressing rod 17b. The other end of the piston 18b is provided with a valve seat 16 located at a gas outlet 15b provided outside the primary chamber 11b.
A valve body 14b that can be fitted with b is formed.

In this embodiment, the ratio of the area B of the diaphragm 10b to the area B'of the tip of the piston 18b on the secondary chamber 12b side is 7: 1.6.

The set value of such a vapor phase line pressure adjusting valve 9b can be obtained as follows.

That is, as the set point of the vapor phase line pressure adjusting valve 9b, the inlet pressure P ₁ is set in the same manner as in the above embodiment.
Is 5 kgf / cm ² , and the outlet pressure P ₂ is 0.5 kgf / cm 2.
^When selected as ² , B: B '= 7: 1.6 as described above (1) Further, 5B' = 0 as in the above embodiment. .5B + Sp ……………………………… (2) However, Sp: At the set point, the force that the spring 13a biases the diaphragm 10a is (5) (1.6) from (1) and (2). / 7) B = 0.5B + Sp Sp = 0.64B (3) If Sp is constant, the relationship between P ₁ and P ₂ is shown in Table 2 and FIG. 6
become that way.

[0040]

[Table 2]

As shown in FIG. 6, P ₁ in this embodiment
The slope of the curve B showing the correlation between P and P ₂ is smaller than the slope of the curve A of the above-mentioned embodiment, so that according to this embodiment, P
It is understood that the fluctuation of P ₂ is suppressed even if ₁ largely fluctuates, and a stable gas supply pressure is obtained as shown in FIG.

Although the on-off valve 4 is composed of the back pressure valve 4a and the check valve 4b in each of the above-described embodiments, the present invention is not limited to this. For example, an electromagnetic valve may be provided in the liquid phase line 2. It is also effective to interpose one end of the check valve downstream of the solenoid valve, connect the other end of the check valve to the pressure switch, and control the solenoid valve and the pressure switch by the controller.

[0043]

According to the present invention, the outlet pressure set value of the gas phase line pressure adjusting valve is made higher than the set value of the liquid phase line pressure adjusting valve when the opening / closing means such as the back pressure valve of the liquid phase line is opened, Since the gas phase line is always functioning and gas is supplied to reduce the operation of the liquid phase line, the heat required for the vaporization tube or the like is reduced and the energy efficiency is improved. In addition, fluctuations in the internal pressure of the vaporization cylinder and the frequency of opening and closing the back pressure valve can be reduced, and the useful life of the components can be extended.
By improving the gas-phase line pressure control valve, the gas supply pressure from the gas-phase line can be stabilized.

[Brief description of drawings]

FIG. 1 is a system diagram of a gas phase combined heating and depressurizing system according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a vapor line pressure adjusting valve according to the embodiment of FIG.

FIG. 3 is a diagram showing the opening and closing of the back pressure valve during operation of the embodiment of FIG.
3 is a diagram showing changes with time in the container internal pressure and the vaporization cylinder internal pressure.

FIG. 4 is a cross-sectional view showing a vapor line pressure adjusting valve according to another embodiment of the present invention.

5 is a diagram showing a comparison of changes over time in the pressure inside the container and the gas supply pressure during operation of the pressure regulating valve shown in FIG. 2 and the pressure regulating valve shown in FIG.

FIG. 6 is a graph showing a comparison of the correlation between the inlet pressure P ₁ and the outlet pressure P ₂ in each pressure control valve.

FIG. 7 is a system diagram of a vapor phase combined heating / depressurizing system according to an example of a conventional technique.

8 is a diagram showing the opening / closing of the back pressure valve, and the changes over time in the pressure inside the container and the pressure inside the vaporizing cylinder in the example of FIG. 7. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container 2 Liquid phase line 3 Gas phase line 4 Opening / closing means 4a Back pressure valve 4b Check valve 5 Vaporizing cylinder 6 Heat medium 7 Heat source 8 Liquid phase line pressure adjusting valve 9, 9a, 9b Gas line pressure adjusting valve 10a, 10b Diaphragm 11a, 11b Primary chamber 12a, 12b Secondary chamber 13a, 13b Spring 14a, 14b Valve body 15a, 15b Gas outlet 16a, 16b Valve seat 17b Push rod 18b Piston

Claims (3)

[Claims] 1. A liquefied gas storage container is inserted with a vapor phase line and a liquid phase line, respectively, and the liquid phase line is heated by an on-off valve which is opened when the inside of the container falls below a set pressure. After passing through the vaporization cylinder filled with the medium,
Via the pressure adjusting valve of the liquid phase line that controls the valve opening to adjust the outlet pressure to the set pressure, communicate with the gas outlet side,
In the vapor phase line, a pressure regulating valve of the vapor phase line for controlling the opening of the valve so as to regulate the outlet pressure according to the pressure difference between the inlet and the outlet, the pressure of the liquid phase line when the on-off valve is opened. A pressure adjusting valve for the gas phase line is provided in which the outlet pressure is set to be higher than the set pressure of the pressure adjusting valve, and the gas phase line is provided with each of the pressure adjusting valve for the gas phase line and the pressure adjusting valve for the liquid phase line. A combined heating and depressurizing device for a vapor phase for a liquefied gas evaporator, characterized in that it joins the liquid phase line on the outlet side of the. 2. The pressure regulating valve of the vapor phase line has a primary chamber communicating with an inlet side of the vapor phase line and a secondary chamber communicating with an outlet side of the vapor phase line, Room and above 2
The secondary chamber is isolated via a diaphragm, and the diaphragm is biased toward the primary chamber by an elastic means, and one end of a valve element movable in the biasing direction or the opposite direction is moved to the diaphragm. 2. The liquefied gas evaporator according to claim 1, wherein the liquefied gas evaporator is connected to the other end of the valve body so that the other end of the valve body can be fitted with a valve seat provided on the gas outlet of the primary chamber. Gas phase combined heating and decompression device. 3. The pressure regulating valve of the vapor phase line has a larger cross-sectional area than the primary chamber communicating with the inlet side of the vapor phase line and the primary chamber communicating with the outlet side of the vapor phase line. A secondary chamber, and a diaphragm urged toward the primary chamber and a pressing means connected to the diaphragm and protruding into the primary chamber are provided in the secondary chamber, and the urging direction or its direction. One end of a piston movable in the opposite direction is fitted in the primary chamber so as to be able to contact the pressing means,
The liquefied gas evaporator according to claim 1, wherein the other end of the piston is provided with a valve body that can be fitted into a valve seat provided in the gas outlet on the primary chamber side. Combined heating and decompression device for gas phase.