JPS6259602B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an evaporator using an evaporator.

When condensate is stored on the heating side of the evaporator, the air from which the condensate has been separated is extracted from the heating side through the gas vent, but if the liquid level fluctuates, only one gas vent is used. In some cases, it must be installed at the highest position. Air is heavier than steam, so it accumulates at the bottom, and when the liquid level is low, a considerable amount of the supplied steam is extracted from the gas vent and exhausted.
This method has disadvantages in that it causes a decrease in efficiency and causes problems such as an excessive intake amount of the air extraction device.

The present invention eliminates the above-mentioned drawbacks of the conventional method and reduces the amount of steam discharged by providing a plurality of gas venting ports with different heights and using only the lowest gas venting port above the liquid level as the main gas venting port. It is an object of the present invention to provide an evaporation device that prevents a decrease in efficiency by reducing the amount of air taken in by the extraction device, and allows the suction amount of the extraction device to be appropriate.

The present invention provides an evaporator using an evaporator,
When a plurality of gas vent ports on the heating side are provided at different heights and the liquid level height of the condensate stored in the heating side changes, above the liquid level and above the liquid level, The evaporator is characterized in that only the gas venting port closest to the liquid surface is opened as the main gas venting port.

The present invention will be described with reference to the drawings, in which 1 is an evaporator, 2 is a raw solution inlet,
3 is a concentrate outlet, 4 is a steam inlet, 5 is a steam outlet,
6 is a condensate outlet, and 7 is a pump.

Control of the evaporation capacity of the evaporator 1 will be described.

Condensed liquid is stored on the heating side of the evaporator 1. The control mechanism 8 includes a flow rate control mechanism that detects the condensate discharge flow rate of the pump 7 and controls the flow rate to match the set flow rate by operating the regulating valve 9, and a flow rate control mechanism that detects the condensate water level stored on the heating side of the evaporator 1. Then, change the setting value of the flow rate of the flow rate control mechanism and set the adjustment valve 9.
and a water level control mechanism for controlling the condensate water level to match a set water level determined according to the load.

In the structure of this embodiment, when a steady state is reached for a certain load, the evaporation amount of the evaporator 1 matches the condensation amount, so the evaporation amount (evaporation capacity) of the evaporator 1 is adjusted to a predetermined value. To set the value,
In the control mechanism 8, the condensate discharge flow rate of the pump 7 may be set, that is, the opening degree of the regulating valve 9 may be set.

On the other hand, by changing the water level of the condensed liquid in the evaporator 1, the heat transfer area changes and the amount of evaporation can be changed. Therefore, in order to set the evaporation amount (evaporation capacity) of the evaporator 1 to a predetermined value, the water level is set in the control mechanism 8.

When changing the evaporation capacity of the evaporator 1, the required evaporation amount (=condensate discharge flow rate) in the control mechanism 8 is set, for example, in the central control room. When the discharge flow rate of the pump 7 is detected and a difference from the set flow rate is found, an instruction to change the water level is given to the water level control mechanism, and an instruction is further given to the regulating valve 9 to return the flow rate to the set value, and the current The condensate level will match the load capacity.

For example, in order to lower the evaporation capacity, the flow rate setting value is lowered, and the flow rate control mechanism issues an instruction to increase the water level to the water level control mechanism, and the water level control mechanism throttles the regulating valve 9, reducing the flow rate flowing through the pump 7 and lowering the water level. The heat transfer area decreases, and through this process, the amount of evaporation decreases. To increase the evaporation capacity, perform the reverse operation.

In the control mechanism 8, by combining a water level control mechanism in addition to a flow rate control mechanism, the water level (i.e., heat transfer area) can be confirmed, and the water level can be detected for performing gas venting control as described below. This enables safe and reliable evaporation capacity control.

If such load control is performed, other evaporators will not be affected, and the load can be easily finely adjusted.

The evaporator 1 has a two-pass structure, which increases the amount of liquid per heat transfer tube 14 to prevent the liquid film from running out. The liquid supply section 15 and the liquid extraction section 16 have partition plates 17 and 18, respectively, and the partition plate 18 of the liquid extraction section 16 has an opening 19 in the center so that evaporated vapor can be separated. .

Reference numeral 20 is a gas vent port, and 21, 21', and 21'' are gas vent valves that serve as main gas vent ports, and are provided at different heights. 22 is a gas vent pipe that is connected to the bleed device. Yes.Gas vent valve 2
1, 21', and 21'' are controlled by the liquid level control mechanism 8 in the control mechanism 8. For example, when the condensate level rises from the lowest position, the gas vent valve that is below the liquid level is turned off. Close, but always ensure that the lowest vent valve above the liquid level is open.Thus, if the liquid level is falling, open the vent valve when its mouth appears above the liquid level. Make sure to open it.The air after separating the condensate will accumulate at the bottom of the evaporator, so vent the gas from the bottom as much as possible.If you always open the upper gas vent valve, the steam inlet will be removed. The steam entering from 4 will escape directly and the efficiency will decrease, and the suction amount of the extraction device will become excessive.
This can be prevented. Since some air is blown up in the evaporator 1 and reaches the upper part, a gas vent 20 is provided to extract this air.

Note that it is preferable to use a thin film falling evaporator (FFE) as the evaporator 1.

The present invention provides an evaporator using an evaporator, in which a plurality of gas vent ports on the heating side are provided at different heights, and when the liquid level of the condensate stored in the heating side changes, the liquid By opening only the gas venting port above the surface and closest to the liquid surface as the main gas venting outlet, it is possible to provide an evaporator that prevents a decrease in efficiency and prevents an excessive intake amount of the air extraction device. This has an extremely large practical effect.

[Brief explanation of the drawing]

The drawing is a flow diagram for an embodiment of the invention. 1... Evaporator, 2... Raw solution inlet, 3... Concentrate liquid outlet, 4... Steam inlet, 5... Steam outlet, 6... Outlet, 7
...Pump, 8...Control mechanism, 9...Adjusting valve, 14...Heat transfer tube, 15...Liquid supply section, 16...Liquid extraction section, 17...
Partition plate, 18... Partition plate, 19... Opening, 20... Gas venting port, 21, 21', 21''... Gas venting valve, 22
...Gas vent pipe.

Claims (1)

[Claims] 1. In an evaporator using an evaporator, when a plurality of gas vent ports on the heating side are provided at different heights and the liquid level of the condensate stored in the heating side changes, the liquid level An evaporator characterized in that only the gas venting port located above and closest to the liquid surface is opened as the main gas venting outlet.