JPH07225004A - Steam heating apparatus - Google Patents

Abstract

PURPOSE:To accurately set heating temperature by using a vacuum pressure reducing valve capable of precisely setting minute pressure. CONSTITUTION:A vacuum pressure reducing valve 51 is arranged on the primary side of a jacket part 53. An ejector 59 is connected to the secondary side of the jacket part 53. Upper part of the vacuum pressure reducing valve 51 is connected to the vicinity of a suction port of the jacket part 59 by means of a pressure reducing pipe line 73.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to heating an object to be heated in a heat exchanger with steam, and particularly, the heating temperature thereof is 100.
The present invention relates to a steam heating device suitable for a relatively low temperature of about C or lower. Specifically, it is used for steam heating of various reaction kettles used for polymerization reaction, food distilling devices, concentrating devices, sterilizing devices, and the like. The object to be heated in these cases often suffers thermal damage due to a slight temperature rise, and it is necessary to maintain the heating temperature accurately.

[0002]

2. Description of the Related Art As a conventional steam heating apparatus, a pressure reducing valve for vacuum is arranged on the primary side of a heat exchanger and a pressure reducing pump is arranged on the secondary side of the heat exchanger to reduce the pressure inside the heat exchanger. As a state, there has been used one that heats an object to be heated with steam at a temperature of about 100 ° C. or lower by supplying low-pressure, that is, low-temperature heating steam from a vacuum pressure reducing valve. The heating steam generated in a boiler or the like has a correlation between its pressure and temperature, and the temperature can be proportionally lowered by lowering the pressure.

As the vacuum pressure reducing valve used in the above-mentioned conventional steam heating device, for example, the one disclosed in Japanese Utility Model Laid-Open No. 63-14311 has been used. This is because the secondary side, that is, the outlet side pressure is received on one surface of the diaphragm as the pressure receiving response portion, the pressure setting spring is coupled to the other surface, and the pressure setting spring is arranged in a tensioned state.
The outlet side, that is, the heat exchanger side is set and maintained at a predetermined vacuum pressure below atmospheric pressure.

[0004]

The conventional steam heating device using the vacuum pressure reducing valve described above has a problem that the heating temperature cannot be accurately set. This is because it is not possible to accurately set a minute pressure in the vacuum pressure reducing valve, and thus it is not possible to accurately set the heating steam temperature.

The pressure of the vacuum pressure reducing valve is set by changing the spring load of the pressure setting spring by an external operation. When setting a minute pressure, the spring length is minutely changed to reduce the spring load. This is because it must be changed, and it is difficult to minutely change the length of this spring with high accuracy. The spring length is usually changed by a screw mechanism connected to the spring, but it is practically impossible to make a fine displacement with high precision due to play in the screw mechanism. In particular, when the spring constant of the pressure setting spring is large, the spring load changes greatly even with a slight change in the spring length, which makes it difficult to set the pressure more accurately.

Therefore, a technical problem of the present invention is that the spring load of the vacuum pressure reducing valve in the steam heating device can be minutely changed without minutely changing the spring length, so that the minute pressure, that is, the temperature can be controlled. It is to be able to perform the setting accurately.

[0007]

[Technical Means for Solving the Problems] The technical means of the present invention taken to solve the above-mentioned problems are a heat exchanger, a vacuum pressure reducing valve disposed on the primary side of the heat exchanger, It consists of a decompression pump arranged on the secondary side of the heat exchanger, and heats the object to be steamed by decompressing the inside of the heat exchanger, and the pressure on the outlet side of the pressure receiving part of the vacuum pressure reducing valve is applied. The desired vacuum pressure is applied to the opposite side to the opposite side.

[0008]

[Operation] The heated steam whose pressure has been reduced to a predetermined pressure, that is, the temperature by the vacuum pressure reducing valve, is supplied to the heat exchanger which is maintained in a reduced pressure state by the pressure reducing pump, so that the object to be heated is steam-heated. To do. Condensate generated by heating is sucked by the decompression pump and removed from the system.

By applying a desired vacuum pressure to the side opposite to the side to which the outlet side pressure of the pressure receiving valve of the vacuum pressure reducing valve is applied, the vacuum pressure acts on both sides of the pressure receiving valve to cancel them. Therefore, the load received by the pressure receiving response part becomes small. The smaller the load is, the smaller the spring load of the pressure setting spring of the vacuum pressure reducing valve may be, and the smaller spring load can also make the spring constant smaller. Therefore, since the spring constant is small, it is not necessary to change the spring length minutely when the spring load is minutely changed to set the minute pressure, that is, the temperature. By changing it, the spring load can be minutely changed, the difficulty of minutely changing the spring length is eliminated, and the minute pressure, that is, the temperature can be set accurately.

[0010]

EXAMPLES Examples showing specific examples of the above technical means will be described. FIG. 1 shows the overall configuration of the steam heating device. In this embodiment, an example in which the reaction kettle 50 is used as the heat exchanger is shown. The reaction vessel 50 is provided with an agitator 54, an object to be heated inlet 55 and an object to be heated outlet 56, and a jacket portion 53 is provided over substantially the entire circumference. A steam supply pipe 52 is connected to the jacket portion 53 via a vacuum pressure reducing valve 51. The lower portion of the jacket portion 53 is provided with a steam trap 57 and a bypass valve 5.
8 to the ejector 59.

A tank 60 and a circulation pump 61 are sequentially provided on the outlet side of the ejector 59 and communicated with each other through a circulation path 62. The water in the tank 60 is circulated by the circulation pump 61, and the ejector 59
To generate suction force on the ejector 59 and the tank 6
0, the circulation pump 61, and the circulation path 62 constitute a decompression pump. A cooling water supply pipe 63 is connected to the upper portion of the tank 60 via a valve 64. In the tank 60, level sensors 65 and 66 for detecting the water level in the tank and a temperature sensor 67 for detecting the water temperature are attached. The valve 64 is controlled to open and close based on the detection values of the temperature sensor 67 and the level sensor 66. The circulation path 62 is branched to provide a surplus water discharge path 69 via a valve 68. The level sensor 65 opens and closes the valve 68 to discharge excess water.

The circulation passage 62 is branched to connect the passage 71 to the jacket portion 53 via the valve 70. By opening the valve 70, the water in the circulation path 62 can be supplied to the jacket portion 53 to heat the reaction kettle 50 with low-temperature hot water, or to cool it with cooling water. The cooling water supply pipe 63 is also branched and can be cooled by connecting to the jacket portion 53 via the valve 72.

The pressure reducing pipe 73 is taken out from the vicinity of the suction port of the ejector 59 and connected to the upper portion of the vacuum pressure reducing valve 51.
The vacuum pressure reducing valve 51 has an inlet 2 and an outlet 3 formed in a valve casing 1 as shown in the detailed structure of FIG.
A valve port 5 is formed in the valve seat member 4 attached to the. The inlet 2 is connected to the steam supply pipe 52, and the outlet 3 is connected to the jacket portion 53. A flat plate-shaped main valve body 6 is arranged so as to face the valve opening 5 by a coil spring 17 so as to be biased in the valve closing direction, and the upper surface thereof is joined to the connecting rod 8 of the piston 7.

The upper portion of the piston 7 is connected to the pilot valve chamber 14 via the communication passage 13. A pilot valve body 15 is arranged at the end of the pilot valve chamber 14 with a coil spring 16 biasing the valve body 15 in the valve closing direction. The pressure on the inlet side acts on the pilot valve body 15 through the inlet pressure communication passage 20. A pilot valve rod 18 is continuously provided on the upper portion of the pilot valve body 15 and is joined to a diaphragm 19 as a pressure receiving response portion via the lower diaphragm retainer 10. Lower chamber 30 of diaphragm 19
The pressure on the outlet side is exerted by the outlet pressure communication passage 31. The upper diaphragm retainer 2 is provided on the upper surface of the diaphragm 19.
A coil spring 22 for pressure setting is arranged via 1. The upper diaphragm retainer 21 and the lower diaphragm retainer 10 are arranged so as to sandwich the diaphragm 19 by screwing.

A substantially cylindrical female screw member 32 is arranged above the coil spring 22, and a pressure adjusting screw 23 is threaded through the center thereof. The pressure adjusting screw 23 is attached to the center of the upper part of the upper casing 33, and a recess groove is formed in a part of the pressure adjusting screw 23 so that the retaining ring 25 is fitted thereto. Mount it so that it will not be displaced. Female screw member 32 and upper casing 33
A guide member 34 is disposed between the female screw member 32 and the female screw member 32 so that the female screw member 32 is vertically displaceable and does not rotate. The coil spring 22 arranged between the female screw member 32 and the upper diaphragm retainer 21 is attached at both ends by welding. An urging spring 35 that urges the female screw member 32 downward is arranged above the female screw member 32.

The upper surface of the diaphragm 19 and the upper casing 3
3 to form a closed vacuum pressure chamber 36, and the ejector 5 through the communication hole 37 and the pressure adjusting valve 38 by the pressure reducing pipe 73.
Connect with the suction port of 9. Therefore, the vacuum pressure chamber 36 can be maintained at a desired vacuum pressure by the suction force of the ejector 59. A desired vacuum pressure can be arbitrarily set by using the pressure adjusting valve 38 as a primary pressure adjusting valve, but it is not always necessary if the suction force of the ejector 59 is stable.

Next, the operation will be described. Reaction kettle 5 shown in FIG.
When the object to be heated in 0 is steam-heated, the circulation pump 61 is driven to generate a suction force in the ejector 59 to bring the inside of the jacket portion 53 into a predetermined vacuum state. The steam reduced in temperature to a predetermined pressure, that is, the temperature, is supplied from the vacuum pressure reducing valve 51 to the jacket portion 53 to heat the object to be heated with steam. Condensate generated by heating the object to be heated is sucked by the ejector 59 through the steam trap 57 and reaches the tank 60.

In the vacuum pressure reducing valve 51 shown in FIG. 2, when the pressure on the outlet 3 side, that is, the pressure on the jacket portion 53 becomes lower than the pressure set by the coil spring 22, the spring load of the coil spring 22 is overcome and the diaphragm 19 is displaced downward. The pilot valve body 15 is opened via the pilot valve rod 18, the high-pressure fluid on the inlet 2 side acts on the upper surface of the piston 7 through the communication passages 20 and 13, and the piston 7 is displaced downward. By opening the main valve body 6 and replenishing the outlet 3 side with the high pressure steam on the inlet 2 side, the pressure on the outlet 3 side is raised to the set pressure. When the set pressure is reached, the pilot valve body 15 closes in balance with the spring load that pushes the diaphragm 19 upward, and the main valve body 6 also closes to maintain the set pressure.

The vacuum pressure chamber 36 of the vacuum pressure reducing valve 51 is maintained at a desired vacuum pressure. For example, when the vacuum pressure on the outlet 3 side is 30 to 100 torr or less, the vacuum pressure acts on the upper and lower surfaces of the diaphragm 19 if the inside of the vacuum pressure chamber 36 is maintained at 100 torr or more. By offsetting each other, the load applied to the diaphragm 19 becomes smaller by that amount, and the spring load of the coil spring 22 that balances as the load becomes smaller can also be made smaller. If the spring load of the coil spring 22 can be reduced, the spring constant also becomes small, and the displacement amount of the spring, that is, the tension amount in this embodiment can be increased when a predetermined load is applied. Therefore, it is necessary to make a minute change. Disappears,
The pressure can be set accurately.

[0020]

EFFECT OF THE INVENTION By applying a desired vacuum pressure to the side opposite to the side to which the pressure on the outlet side of the pressure receiving valve of the pressure reducing valve for vacuum in the steam heating device is applied, a pressure is set when a minute pressure, that is, a temperature is set. Since it is not necessary to minutely change the length of the setting spring and the difficulty is eliminated, the minute pressure, that is, the temperature can be accurately set. Therefore, the heating temperature in the heat exchanger can be accurately set, and heat damage to the object to be heated can be prevented.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a steam heating device of the present invention.

FIG. 2 is a cross-sectional view of a vacuum pressure reducing valve used in the steam heating apparatus of the present invention.

[Explanation of symbols]

 2 Inlet 3 Outlet 5 Valve port 6 Main valve body 7 Piston 19 Diaphragm 22 Coil spring 36 Vacuum pressure chamber 37 Communication hole 50 Reactor 51 51 Vacuum reducing valve 52 Steam supply pipe 53 Jacket 59 Ejector 60 Tank 61 Circulating pump 62 Circulating path 73 Decompression line

Claims (1)

[Claims] 1. A heat exchanger, a vacuum pressure reducing valve arranged on the primary side of the heat exchanger, and a pressure reducing pump arranged on the secondary side of the heat exchanger, wherein the inside of the heat exchanger is decompressed. A steam heating apparatus for heating an object to be heated by steam, wherein a desired vacuum pressure is applied to a side opposite to a side to which an outlet side pressure of a pressure receiving portion of a vacuum pressure reducing valve is applied.