JP2646003B2 - Decompression steam heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for heating an object to be heated at a relatively low temperature (normally 100 ° C. or lower).
The present invention relates to a reduced-pressure steam heating device capable of performing a heat treatment safely and effectively.

[Related Art] In the steps of reaction and drying, for example, in the case of pharmaceuticals and the like, there are very many cases where an object to be heated is heated at a relatively low temperature of 100 ° C or lower.

In such a case, although hot water heating has conventionally been the mainstream, in hot water heating, uneven temperature due to drift is likely to occur,
Since there are problems such as an increase in the space for installing the apparatus and difficulty in operation at a heating temperature of around 100 ° C., a heating system using reduced-pressure steam has recently been put into practical use.

As an example of such a reduced-pressure steam heating device, a system shown in FIG. 5 is generally known. In this heating device, a pressure reducing valve, a pressure automatic control valve, or a temperature automatic control valve 2 (hereinafter sometimes collectively referred to as a control valve) is connected to the steam inlet side of the indirect heating vessel 2, and the steam outlet side is connected to the steam outlet side. The water-sealed vacuum pump 3 is connected via a steam trap 4.

In the heating device configured as described above, first, the non-condensable gas after the secondary side of the pressure reducing valve 1 is exhausted by the water-sealed vacuum pump 3 to be kept in a vacuum, and steam is supplied to the pressure reducing valve 1. The amount of steam to be supplied is adjusted by the pressure reducing valve 1 so that the pressure on the secondary side becomes a predetermined pressure.

On the other hand, the steam supplied to the indirect heating vessel 2 through the pressure reducing valve 1 is heat-exchanged to maintain the indirect heating vessel 2 at a predetermined temperature, becomes a drain, passes through the steam trap 4 and passes through the water ring vacuum pump 3. Is discharged from

[Problems to be Solved by the Invention] In the above-described conventional reduced-pressure steam heating apparatus, since the steam trap 4 is used, non-condensable gas generated by pressure reduction and non-condensation contained in steam are used. The intermittent discharge of the oxidizing gas cannot be performed smoothly, causing a decrease in the heat transfer coefficient. Further, there is a problem that a temperature change peculiar to the steam trap operation is unavoidable and the temperature stability is lacking.

Further, when the unsealed vacuum pump 3 is used as the depressurizing pump and water is used as the sealing liquid, there is a problem that the exhaust amount and the ultimate vacuum degree greatly change depending on the temperature of the sealing liquid. Therefore, in a system with large load fluctuations, if the drain amount fluctuates greatly, the sealing water temperature will fluctuate as a result,
Exhaust capacity also changes. That is, when the load is large, the sealing water temperature rises and the amount of exhaust gas decreases, and as a result, the non-condensable gas cannot be discharged smoothly, causing a decrease in the heat transfer coefficient. When the size is reduced, there are various problems to be solved, such as a decrease in the sealing water temperature and an increase in the amount of exhaust gas, which results in the injection of live steam and a decrease in thermal efficiency.

Means for Solving the Problems The present invention has been made to solve the above problems, and is provided with a control valve on the steam inlet side of the indirect heating vessel and a water ring vacuum pump on the steam outlet side. A reduced-pressure steam heating device, wherein a heating mechanism is used to heat an object to be heated at a relatively low temperature by the indirect heating container, wherein a throttle mechanism is provided between the indirect heating container and a water ring vacuum pump. And a reduced-pressure steam heating device provided with a control device for controlling the sealing temperature of the water-sealed vacuum pump.

[Operation] By providing a throttle mechanism, non-condensable gas contained in steam and non-condensable gas leaking into the system from outside the system can be smoothly and continuously discharged, and furthermore, the live steam is water-sealed vacuum. Prevents pumps from being sucked in large quantities.

Further, by controlling the water sealing temperature of the water sealing type vacuum pump, it is possible to reduce the suction of live steam and to discharge the non-condensable gas generated in the system more smoothly and continuously.

Embodiment of the Invention FIG. 1 is a system diagram of an embodiment of the present invention, in which a pressure reducing valve 1 is attached to a steam inlet side of an indirect heating vessel 2 and a water ring vacuum pump 3 is attached to a steam outlet side. A throttle mechanism 5 (orifice in this embodiment) is provided between the container 2 and the water-sealed vacuum pump 3. Reference numeral 6 denotes a supply port of the sealed liquid of the water-sealed vacuum pump 3. In this embodiment, water is supplied from the supply port 6 to maintain the vacuum.

In the reduced-pressure steam heating device configured as described above, first, the non-condensable gas after the secondary side of the reduced-pressure valve 1 is exhausted by the water-sealed vacuum pump 3 to maintain the vacuum,
Steam is supplied to the pressure reducing valve 1. The amount of steam to be supplied is adjusted by the pressure reducing valve 1 so that the pressure on the secondary side becomes a predetermined pressure. That is, when the heat load of the indirect heating vessel 2 increases, the pressure on the secondary side of the pressure reducing valve 1 decreases. Therefore, the pressure reducing valve 1 opens to maintain a predetermined pressure, and conversely, when the heat load decreases, the pressure reducing valve 1 decreases. The pressure on the secondary side rises, and the pressure reducing valve 1 is throttled to maintain a predetermined pressure, and the pressure is always kept constant.

On the other hand, the steam supplied to the indirect heating vessel 2 through the pressure reducing valve 1 is subjected to heat exchange to maintain the indirect heating vessel 2 at a predetermined temperature. It is discharged from the vacuum pump 3. Here, the throttle mechanism 5 enables smooth and continuous discharge of non-condensable gas contained in steam and non-condensable gas leaked from outside the system into the system. A large amount is prevented from being sucked into the sealed vacuum pump 3.

FIG. 2 is a system diagram showing another embodiment of the present invention. In the present embodiment, three indirect heating vessels 2a, 2b, 2c are juxtaposed, and automatic temperature control valves 1a, 1b are respectively provided on the steam inlet side.
And an automatic pressure control valve 1c, and each indirect heating vessel 2a-2c
Are connected to the primary side of a distributor 7 via throttle mechanisms (needle valves in this embodiment) 5a, 5b, 5c, respectively, and a water ring vacuum pump is connected to the secondary side of the distributor 7. 3 are connected.

Here, each automatic control valve 1a-1c and water ring type vacuum pump 3
Is the same as that of the embodiment of FIG.
By providing the squeezing mechanism 5a to 5c for each of the indirect heating vessels 2a to 2c, it becomes possible to reduce the intake of live steam even if each of the indirect heating vessels 2a to 2c is set to a different heating temperature. , Economical operation can be performed. This is because the use of the needle valves in the throttle mechanisms 5a to 5c allows the optimum throttle opening to be set for any temperature setting and load fluctuation.

FIG. 3 is a system diagram showing still another embodiment of the present invention. In this embodiment, the basic configuration is the same as that of the embodiment shown in FIG. 1. However, by controlling the water sealing temperature of the water ring vacuum pump 3, the suction of live steam is further reduced. .

In the figure, reference numeral 8 denotes a gas-liquid separation tank, which is connected to the secondary side of the water-sealed vacuum pump 3 and separates the drain and the sealed water discharged from the water-sealed vacuum pump 3 into gas-liquid and is separated. The non-condensable gas is released into the body through the gas outlet 9,
The sealed water mixed with drain is discharged from the lower part and the sealed water supply port 6
And supplied to the water-sealed vacuum pump 3 again. Further, the sealed water mixed with the overflowed drain is discharged from the drain discharge port 10. An automatic flow control valve 11 detects the temperature of the sealed water in the gas-liquid separation tank 8, opens and closes the automatic flow control valve 11 by a signal corresponding to a deviation from a set value, and opens a sealed vacuum from the supply port 6. The flow rate of the sealed water supplied to the pump 3 is controlled.

In this embodiment configured as described above, the non-condensable gas and the sealed water mixed with the drain discharged from the water-sealed vacuum pump 3 are separated in the gas-liquid separation tank 7, and the separated drain is mixed. The sealed water circulated as the sealed water of the water-sealed vacuum pump 3 and the sealed water mixed with the drain corresponding to the amount of drain generated is overflowed from the gas-liquid separation tank 10 and discharged. It is.

By the way, when the sealing water is circulated, the sealing water temperature reaches a temperature equilibrium with the secondary pressure of the automatic pressure control valve (pressure reducing valve) 1c, and finally the gas exhaust capacity is completely lost, so that live steam is lost. , But the non-condensable gas generated in the system cannot be exhausted.

In the present embodiment, a cooling water supply port 6 is provided in a water sealing circuit connecting the gas-liquid separation tank 8 and the water ring vacuum pump 3, and an automatic flow rate control valve 11 is provided in the cooling water supply path.
The water-sealing vacuum is adjusted by adjusting the amount of the water to be sealed so that the water-sealing temperature is slightly lower than the heating temperature of the indirect heating vessel 2 (the temperature of steam which is in equilibrium with the operating pressure) by the automatic flow rate control valve 11. The exhaust capacity of the pump 3 is restored, and the exhaust capacity can be freely controlled. This makes it possible to reduce the intake of live steam and smoothly and continuously discharge the non-condensable gas generated in the system.

FIG. 4 is a system diagram of another embodiment of the present invention. In this embodiment, the temperature control of the sealed water shown in the embodiment of FIG. 3 is indirectly performed. That is, in this embodiment,
A heat exchanger 12 connected between the cooling water inlet 6a and the cooling water outlet 13 is provided in the water sealing circuit, and an automatic flow rate control valve 11 is provided at the cooling water inlet 6a. Indirect cooling and automatic flow control valve 11
Is opened and closed to adjust the flow rate and control the temperature of the cooling water supplied to the heat exchanger 12.

[Effects of the Invention] As is apparent from the above description, the present invention relates to a decompression steam heating device in which a control valve is attached to the steam inlet side of the indirect heating vessel and a water ring vacuum pump is attached to the steam outlet side. A throttle mechanism is provided between the heating vessel and the water ring vacuum pump, so that non-condensable gas generated in the system during operation is smoothly discharged to prevent a decrease in heat transfer heat coefficient, Was prevented from being sucked into the water ring vacuum pump. Also, with this configuration,
A plurality of indirect heating vessels having different heating temperatures can be drawn in by one water-sealed vacuum pump. Further, by controlling the water seal temperature of the water seal vacuum pump, the suction of live steam can be reduced, and efficient and economical operation can be achieved.

[Brief description of the drawings]

1 to 4 are a system diagram of an embodiment of the present invention and FIG.
The figure is a system diagram of an example of a conventional reduced pressure steam heating device. 1: pressure reducing valve, 1a, 1b: automatic temperature control valve, 1c: automatic pressure control valve, 2-2c: indirect heating vessel, 3: water ring vacuum pump, 5-5
c: throttle mechanism, 8: gas-liquid separation tank, 11: automatic flow control valve, 1
1: heat exchanger.

Claims (2)

(57) [Claims] 1. A control valve is provided on a steam inlet side of an indirect heating vessel.
Further, in a device which is provided with a water ring vacuum pump on the steam outlet side and heats an object to be heated at a relatively low temperature by the indirect heating container, a throttle mechanism is provided between the indirect heating container and the water ring vacuum pump. A reduced pressure steam heating device characterized by comprising: 2. A reduced-pressure steam heating apparatus according to claim 1, further comprising a control device for controlling a sealing temperature of said water-sealed vacuum pump.