JPH0278856A - Steam supplying system - Google Patents

Abstract

PURPOSE:To provide a substantial amount of thermal transfer and further enable a heating of uniform temperature to be attained by a method wherein steam is supplied to an indirect heating container through a pressure reduced part and an item to be heated is heated further, and air is introduced into a pipe connecting a pressure reduction valve with the indirect heating container. CONSTITUTION:A pipe 23 for connecting an indirect heating container 21 with a pressure reducing valve 22 is provided with an air feeding pipe 24 and a temperature sensor 26. The air feeding pipe 24 is provided with a control valve 25, the valve is opened or closed in such a way as it shows a desired steam temperature in response to a signal from the temperature sensor 26. These temperature controlling operations are carried out by an adjusting meter 27 provided with a set temperature inputting means. When a secondary side of the pressure reducing valve 22 is sucked by a vacuum pump A to become a negative pressure, air is introduced from the air feeding pipe 24 simultaneously with a supplying of steam from the pressure reducing valve. A temperature of steam at that time becomes a saturation temperature corresponding to a partial pressure of steam inclusive and its steam contains air, so that a heat transmittance coefficient is reduced. In this system, the pressure reducing valve 22 is provided and a steam supplying pressure is stable, so that a temperature control with an adjuster meter 27 is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a steam supply system for efficiently heat-treating objects to be heated by supplying steam to an indirect heating container.

<Prior Art> Heat treatment is widely and generally carried out in various manufacturing plants, and in such heat treatment, the object to be heated is subjected to h0 at a high temperature of 100°C or higher or a low temperature of 100°C or lower. When heating with positive pressure steam, high pressure steam generated in a boiler is reduced to a desired pressure via a pressure reducing valve and steam at 100° C. or higher is supplied to the indirect heating vessel. In addition, when heating with negative pressure steam, a pressure reducing valve is placed on the primary side of the indirect heating container, a vacuum pump is placed on the secondary side, and by suctioning with the pump, negative pressure is generated after the pressure reducing valve. Steam of 100'C or less is generated and supplied to the indirect heating vessel. The pressure reducing valve here is a special pressure reducing valve that performs the opposite action of the pressure reducing valve for positive pressure. In other words, if the secondary pressure falls below the set pressure of the pressure reducing valve, the valve opening is opened against the internal force once the pressure has been set, allowing steam to flow out to the secondary side.

<Problem to be solved by the invention> The advantages of heating with steam in this way are that the enthalpy is larger than that of hot water, so the amount of heat transferred is large, and the heat transfer coefficient is large, allowing for uniform heating. This is because there is. However, in chemical factories and food factories, for reasons of work safety and product quality, it may be better not to significantly heat the heated object. In other words, although the above-mentioned advantages of steam are good, on the other hand, there is a problem that the heating rate is too fast due to the large heat transmission coefficient. 7J of temperature in hot water heating
It is difficult to use due to O heat unevenness.

Therefore, the technical problem of the present invention is to generate and supply steam that has a large amount of heat transfer, can be heated to a uniform temperature, and can be heated softly.

<Means for solving the problems> The technical means of the present invention taken to solve the above problems are as follows:
In a system that supplies steam to an indirect heating container via a pressure reducing valve to heat-treat objects to be heated, this steam supply system is equipped with a means for introducing air into piping that connects the pressure reducing valve and the indirect heating container. .

This can be applied to both positive pressure steam heating and negative pressure steam heating.

Introducing air into steam means that, according to the law of partial pressures, for example, even if the pressure of the fluid is 2 kg/ci, the partial pressure ratio of the steam is 1.5 to 3/car, and the air is 0.゜5K
If g1a/r, the temperature of the fluid is 1.5Kg/c
It becomes the saturation temperature of steam at m. By changing the air content ratio in this manner, any steam temperature can be generated.

Moreover, this steam has a low heat transmission coefficient due to air being mixed therein, allowing for soft heating.

<Example> An example showing a specific example of the above technical means will be described. (
(See Figures 1 and 2) This embodiment uses a heating system using negative pressure steam.

FIG. 1 is a schematic diagram of an ejector-type vacuum pump A used in the apparatus of the present invention. A tank 1 and a pump 2 are connected through a suction pipe 3 and a discharge pipe 4 to which a temperature sensor 10 is attached, respectively. The discharge pipe 4 is provided with an ejector part 5 and a suction port 6 is formed therein. A cooling water pipe 7 is connected to the tank 1, and an electric valve 8 is installed in conjunction with a temperature sensor 10. An electric valve 9 for fluid pressure feeding is provided between the discharge pipe 4 and the ejector part 5,
It is linked with the electrode rod 11 built into the tank 1.

The fluid in the tank 1 is sucked into the pump 2 from the suction pipe 3, is sent under pressure to the discharge pipe 4 and the ejector part 5, and is returned to the tank 1.
Return inward and circulate. At this time, a suction action is generated in the ejector part 5, and the pressure reaches a saturation pressure with respect to the temperature of the fluid flowing therein. Therefore, by arbitrarily setting the temperature using the temperature sensor 10 provided in the suction pipe 3, the electric valve 8 opens and closes, allowing the cooling water to enter the tank and maintain the desired fluid temperature. Occurs in some cases. Therefore, by adjusting the temperature sensor 10, an arbitrary degree of vacuum can be obtained.

The vacuum pressure generated in the ejector part 5 sucks fluid such as condensate or steam from the suction port 6 and forces it into the tank 1. When the liquid level in the tank 1 reaches a high level, the electrode 11 detects this, and the pressure-feeding electric valve 9 opens to force-feed the fluid to a distant location. When the water level reaches a predetermined low level, the electric valve 9 closes.

FIG. 2 shows a vacuum steam generation and heating device using the ejector type vacuum pump A described above. The pressure reducing valve 22 is connected to the primary side of the indirect heating container 21, and the vacuum pump A shown in FIG. 1 mentioned above is connected to the secondary side to reduce the pressure of the system to negative pressure. The pressure reducing valve 22 is a special pressure reducing valve, and when the pressure inside the indirect heating vessel 21 becomes lower than the set pressure, the valve that was previously closed starts opening and directs the steam on the primary side to the indirect heating vessel 21. supply When the value becomes higher than the desired value, the valve closes again and the supply amount is suppressed.

An air introduction pipe 24 and a temperature sensor 26 are provided in a pipe 23 connecting the indirect heating container 21 and the pressure reducing valve 22. A control valve 25 is attached to the introduction pipe 24 and the temperature sensor 2
Based on the signal from 6, the steam is opened and closed to introduce air to the desired steam temperature. These temperature controls are performed by a controller 27 equipped with a set temperature input means.

When the secondary side of the pressure reducing valve 22 is sucked by the vacuum pump A and becomes a negative pressure, air is introduced through the introduction pipe 24 at the same time as steam is supplied from the pressure reducing valve. The temperature of the steam at that time becomes the saturation temperature corresponding to the partial pressure (pressure) of the steam contained, and since the steam contains air, the heat transmission coefficient becomes small.

In this system, a pressure reducing valve 22 is provided, and since the supply pressure of steam is stable, temperature control using a controller 27 can be performed very easily.

In addition, as mentioned above, the vacuum pump A can be set to an arbitrary degree of vacuum, so if the desired value of the pressure inside the heating container, that is, the setting value of the pressure reducing valve, is set, it is possible to avoid excessive vacuum inside the heating container. It is possible to maintain a constant pressure without overheating.

<Effects of the Invention> According to the present invention, it is possible to generate and supply steam that has a large amount of heat transfer, can be heated at a uniform temperature, and can be heated softly, which improves productivity and product quality. Leads to improvement.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an ejector-type vacuum pump used in the device of the present invention, and Fig. 2 is a system diagram of the vacuum steam generation and heating device of the present invention using the ejector-type vacuum pump shown in Fig. 1. It is. 1: Tank 2: Pump 5: Part of ejector 10: Temperature sensor 20: Vacuum pump 21: Indirect heating container 22: Pressure reducing valve 25:
Control valve 26: Temperature sensor 27: Controller

Claims (1)

[Claims] 1. A system for heat-treating objects to be heated by supplying steam to an indirect heating container via a pressure reducing valve, characterized in that a means for introducing air into the piping connecting the pressure reducing valve and the indirect heating container is provided. steam supply system.