JPS61187902A - Steam condensing device - Google Patents

Abstract

PURPOSE:To make installation cost inexpensive and to reduce sticking of scale by providing an eductor for bleed, a tank for receiving driving water for the eductor, a water circulating pump, a heat exchanger for cooling the driving water and a vent for discharging noncondensible gas. CONSTITUTION:Circulated water circulated by a water circulating pump 5 is fed to an eductor 70 for bleed through a heat exchanger type cooler 6, where the steam separated in a steam/water separator 4 is sucked in the eductor and mixed with afore-mentioned circulated water in a condensing tank 8. The steam is condensed in the circulated water, and the noncondensible gas in the steam rises upward through the liquid in the tank, separating the gas from liquid, and discharged to a tank vent system 8'. On one hand, the temp. of the circulated water rises by the condensation, and increased circulated water is sent to a condensate receiving tank 10 through an overflow line 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a steam condensing device, and more particularly to a steam condensing device suitable for condensing steam from a radioactive waste liquid concentrator.

[Background of the invention]

In conventional waste liquid concentration plants,
As described in No. 7677, the vapor that evaporates in the waste liquid concentrator is sent to the condenser together with non-condensable gas such as air used for measurement of the waste liquid concentrator, where the vapor condenses and becomes non-condensable. Separated from gas. Non-condensable gas is degassed by a vacuum pump, and the condensed liquid is further cooled in a condenser before being transferred to a tank or the like.

FIG. 6 shows a conventional example, in which steam evaporates from an evaporator 3 of a waste liquid concentrator equipped with a recirculation bonder 1 and a heater 2, passes through a steam-water separator 4, and is transferred to a horizontal condenser. Enter 30 and condense. The water condensed here is cooled in the condenser 30,
The condensed water is sent to the condensed water receiving tank 10. In addition, the non-condensable gas that has entered the condenser 30 together with the steam is extracted from the vent of the condenser by the bleed eductor 7, and is removed from the circulating water tank 3.
Enter 1. The driving water for the bleed eductor 7 is repeatedly circulated by the circulating water pump 32 such that it enters the bleed eductor 7 again from the circulating water tank 31 through the circulating water cooler 33.

Conventionally, as the condenser 30, a horizontal 11U-shaped heat exchanger type condenser as shown in Fig. 7 has been mainly used. Steam containing reactive gases enters the condenser shell from the steam inlet nozzle 34 on the condenser shell side, condenses with cooling water flowing through the heat transfer tubes, and is further cooled in the drain cooling zone 35 at the lower part of the shell. It is sent to receiving tank 1o. The cooling water is supplied to the cooling water inlet pipe stand 36.
The water enters the condenser water chamber 37 from there, passes through the U-shaped heat transfer tube 38, and exits from the cooling water outlet pipe holder 39.

However, the conventional device described above suffers from the following six problems.

(1) Mist is included in the steam from the concentrator, but
Since this steam flows to the condenser shell side, it is condensed and then mist enters the drain, and this mist tends to adhere as scale to the inner surface of the condenser shell side and the heat exchanger tubes, especially in the drain cooling zone where the flow rate is low.

(2) As described above, scale is deposited on the heat exchanger type condenser body side, so when cleaning it, it is necessary to pull out the heat exchanger tube bundle and clean it, which is complicated.

Furthermore, it is difficult to clean scale adhering to the surface of the heat exchanger tubes inside the tube bundle.

(3) In the drain cooling zone of the condenser, heat transfer efficiency decreases due to natural convection heat transfer and due to the wall thickness of the heat transfer tubes and scale adhesion to the heat transfer tubes.

(4) Since the non-condensable gas is degassed at a temperature close to 100°C, the amount of entrained vapor is large.

(5) When operating the concentrator under negative pressure, a bleed eductor is used instead of a vacuum pump, but in this case, a circulation pump and a circulating water tank are required to drive the eductor.

[Purpose of the invention]

An object of the present invention is to provide a steam condensing device that has low equipment cost, less scale adhesion, high heat transfer efficiency, and easy maintenance.

[Summary of the invention]

The steam condensing device of the present invention includes an oil/vapor eductor for extracting the steam to be condensed, a tank for receiving the eductor driving water discharged from the eductor, and a circulation system in which water in the tank is returned to the eductor as driving water via a circulation line. The tank is characterized by a heat exchanger disposed in the circulation line for cooling the next drive water, and a vent pipe for exhausting non-condensable gas from the tank.

[Embodiments of the invention]

One embodiment of the present invention will be described in detail with reference to FIG.

In FIG. 1, the waste liquid enters the rainbow heater 2 in the recirculation II f1, where it is heated and sent to the evaporator 3, where it becomes vapor. The evaporated and concentrated liquid is further returned to the recirculation pump, and the above process is repeated to perform concentration. The waste liquid concentrator described above is similar to the conventional example shown in FIG. On the other hand, the evaporated steam is sent from the upper part of the evaporator 3 to a steam/water separator 4, where droplets are removed. Here, the droplets are removed and the vapor is sent to a steam condenser.

The steam condensing device includes a circulation bomb f5, a drain cooler 6, and an eductor 70 for air extraction. It consists of a condensing tank 8.

The circulating water (drain) circulated by the circulation bonder 5 is cooled by a heat exchanger type drain cooler 6 and then sent to the eductor 70 for air extraction. Here, the steam from the steam separator 4 is sucked into the bleed eductor by the negative pressure obtained by flowing circulating water into the bleed eductor 7, and is transferred to the drain cooler 6 in the condensation tank 8. Mix with cooled circulating water.

The structure of the bleed eductor 70 is as shown in FIG.
However, when it passes through the eductor nozzle 27t, the flow rate increases, and the surrounding pressure becomes negative along with this. Steam enters here from the steam inlet nozzle 28, is sucked together with driving water from the eductor nozzle 27, and is discharged through the fluid outlet 29.

The steam mixed with circulating water in the bleed eductor 70 condenses in the circulating water. The temperature of the circulating water increases due to this condensation, and the circulating water enters the condensation tank 8 as it is.

The non-condensable gas contained in the steam is sucked into the bleed eductor 70 together with the steam, mixes with circulating water, and enters the condensation tank 8 . Here, the non-condensable gas rises completely in the liquid in the tank 8, enters the gas phase from the water surface, and is separated from water and steam.

The separated non-condensable gases are discharged to tank vent system 8'. On the other hand, the condensed water is sent to the circulation bonder 5 again and circulated. 9. Drainage increased due to condensation is transferred to condensation tank 8.
The condensed water is sent from the overflow line 9 to the condensed water receiving tank 10.

Figure 3 shows the eductor 7 for bleed air in the tank shown in Figure 1.
This is a detailed view of the friend condensation tank 8 installed.

This condensation tank 8 includes a tank body 14 and an oil/gas eductor 7.
0, a bubble suction prevention plate 15, a cutting board 16, a cleaning spray 17, and a lid plate 18.

The condensed water comes out from the outlet pipe stub 19 of the tank, passes through the circulation pump 5 and the drain cooler 6, and enters the circulation water inlet 2, as shown in FIG.
0 to the bleed air eductor 7. On the other hand, steam containing non-condensable gas passes through the steam port 21 and the eductor 7 for extraction.
Sent to 0. The mixed circulating water and steam flow into the water in the tank 14 from the condensed water outlet 22 while being condensed. The steam condenses in the tank and becomes condensed water, but the non-condensable gas entrained with the steam goes to the bleed eductor 70.
The condensed water flows out from the condensed water outlet 22 and spreads into the water in the tank. Since the condensate outlet 22 of the oil/vapor eductor 70 is installed facing downward or diagonally downward, even non-condensable gas can be removed from the bottom of the tank! It enters up to @S and then floats to the tank liquid level due to buoyancy. A baffle plate 16 is provided horizontally or slightly diagonally in the condensate in the tank to catch the floating non-condensable gas. This increases the contact time of the non-condensable gas with the condensate in the tank and reduces the temperature of the non-condensable gas to the temperature of the condensate. In this way, the non-condensable gas whose temperature has decreased enters the atmosphere at the liquid level and is discharged from the vent 23. Due to this,
Since the temperature of the non-condensable gas is kept low, pent 23
It is possible to reduce the amount of vapor in the non-condensable gas discharged.

A bubble suction prevention plate 15 is provided above the outlet nozzle stub 19 to prevent non-condensable gas from being sucked into the tank. In the figure, 7
1 is a support for a bleed eductor.

Since the liquid level of the tank rises due to the condensed water condensed in the tank, this is transferred from the overflow 24 to the condensed water receiving tank 10 (FIG. 1).

A cleaning spray 17t is provided on the tank top lid 18, and cleaning water is sent in from the cleaning water inlet 25 to remove scale from the inner surface of the tank.

In the above embodiment, the bleed eductor 70 is replaced by the condensation tank 8.
Since the fluid outlet of the eductor is directly in the liquid in the tank 8, pressure loss is small and air extraction efficiency is high.

Figure 4 shows a bleed air eductor 7 installed outside the 1m tank 8.
An embodiment is shown in which the water coming out of the outlet of the tank 8 is guided into the water in the tank 8 through a pipe. This is because the bleed eductor 70 is located outside the condensation tank 8, which is convenient for maintenance.

In the embodiment shown in FIG. 4, as a means of keeping the liquid level in the tank 8 constant, instead of drawing out the condensed water from the overflow line 9 shown in FIG. The liquid level in the tank 8 is controlled by adjusting the opening degree of the AO valve 12 based on the signal from the measurement. A.O.
After passing through the valve 12, the condensate is sent to the condensate receiving tank 10 via a transfer line 13f. According to this, the condensed liquid cooled by the drain cooler 6 is sent to the condensed water receiving tank 10, which is advantageous when a relatively low temperature condensed liquid is required in the condensed water receiving tank 10.

Furthermore, since the discharge pressure of the circulation pump 5 is applied to the transfer line 13, the diameter of the transfer line piping can be made smaller compared to the configuration shown in FIG. In addition, the flow velocity in the pipe can be increased, which is advantageous in preventing scale buildup in the transfer line pipe, and improves maintainability. Furthermore, WI4
In the figure, 9' is a preliminarily provided overflow pipe.

According to the embodiment described above, since the condensed water is circulated by the circulation pump 5, the flow velocity in the heat exchanger tube of the drain cooler 6 and in the condensation tank 8 is high, so that scale adhesion there is prevented.
Heat exchanger type condenser 3 in the prior art shown in Figs. 6 and 7
The scale adhesion can be reduced to 1/2 to 1/4 of the scale adhesion within 0. That is, as is clear from FIG. 5, in the conventional condenser 30 described above, the flow rate in the drain cooling zone is about 0.5rrI/S, and the scale CaSO4
The adhesion amount is 37g/1000Ji' (CaSO410
In contrast, in the embodiment of the present invention, 37JF of 00II adheres in the heat exchanger tube of the drain cooler 6.
11Q/3, the flow rate becomes IIV/s in the condensing tank 8, and the amount of CaSO4 attached to these is 8. ! i+/1
000.9,15Ii/1000 N, and the scale adhesion prevention effect is greatly improved.

〔Effect of the invention〕

The present invention includes the following effects.

(1) Steam is condensed and condensed in a condensation tank that contains water that receives water from the extraction eductor that is cooled and operated by driving water, and the condensation tank that receives the water from its outlet. Since a heat exchanger type condenser is not required, equipment costs for the entire device can be reduced by about 20%.

(2) The condensed water (driving water) is forced to circulate through the air extraction eductor, the condensation tank, the driving water cooler, and then the extraction eductor again through the circulation filter.
The flow velocity in these is high, and therefore scale build-up in the tank and cooler is greatly reduced compared to scale build-up in heat exchanger type condensers in the prior art. Ru. This reduction in scale adhesion, together with the high flow rate, helps to increase the heat transfer efficiency (it is also possible to increase the p thermal efficiency by 10 or more compared to the conventional method).

(3) Since the non-condensable gas in the steam is extracted together with the steam in the steam bleed eductor and cooled in the condensing tank, there is no need for a means for extracting non-condensable gas from the condenser and its There is no need to separately install a cooling means, the equipment is simplified, and the amount of entrained steam contained in the vent from the condensing tank can be reduced by cooling the non-condensable gas. . That is, in the conventional technology, the vent temperature from the condenser is 100°C,
In the present invention, the vent temperature from the condensation tank is 50°C.
Therefore, due to the difference in saturated vapor amount, the amount of entrained vapor during venting is 17.61 in the conventional technology.
G' is 9 (99°C), and in the present invention, 0.08625 is 9/
9 (50° C.), and the present invention can reduce the amount of entrained steam by 99 degrees.

(4) As mentioned in (2) above, since there is less scale adhesion, less maintenance is required for scale removal. Also, when performing maintenance, in the present invention, the condensing tank is a simple tank with no built-in heat transfer tubes, so maintenance and cleaning can be performed simply by removing the tank lid sheet metal, and the drain cooler (condensed water By removing the ice chamber (cooler), the inner surfaces of the heat transfer tubes can be easily cleaned. Conventional condensers flow steam through the shell side, so the tube bundle is pulled out and cleaned to remove scale that adheres to the outside surface of the heat transfer tubes. Cleaning takes 90 hours and the present invention is 1/1 compared to the conventional method! It is possible to clean the same amount of time as before in a time of .

[Brief explanation of the drawing]

Fig. 1 is an overall view of one embodiment of the present invention, Fig. 2 is a cross-sectional view of the bleed eductor, Fig. 3 is a cross-sectional view of the condensation tank of Fig. 1, and Fig. 4 is another embodiment of the present invention. FIG. 5 is a diagram showing the relationship between the flow rate and the amount of Ca5O4 deposited, and FIG. 6 is an overall diagram of a conventional steam condensing facility. FIG. 7 is a sectional view of a conventional condenser. 1... Recirculation pump, 2... Heater, 3...
Evaporator, 4... Steam water separator, 5... Circulation
l/pump, 6...Drain cooler, 7...Bleed air eductor, 8...Condensation tank, 8'...Vent pipe, 9.9'...Overflow line, ]0... Condensed water receiving tank, 11...Liquid level gauge, 12.
・・AO valve 13・Transfer line, 14・
...Tank body, 15...Bubble suction prevention plate, 1
6... Baffle board, 17... Cleaning spray, 18... Lid plate, 19... Outlet pipe stand,
20... Circulating water inlet, 21... Steam inlet, 22
...Condensed water outlet, 23...Vent, 24...
・Overflow, 25...Washing water inlet, 26...
Driving water inlet, 27... Eductor nozzle, 28...
...Steam inlet nozzle, 29...Fluid outlet, 30...
Horizontal condenser, 31... Circulating water tank, 32...
Circulating water pump, 33... Circulating water cooler, 34...
Steam inlet pipe stand, 35... Drain cooling zone, 36... Cooling water inlet pipe stand, 37... Condenser ice chamber, 3
8... Heat exchanger tube, 39... Cooling water outlet nozzle stand,
70... Eductor for bleed air, 71... Support body. Figure 1 Figure 4 Figure 8 speed -/sec)

Claims (1)

[Claims] 1. A bleed eductor that receives driving water and extracts steam to be condensed, a tank that receives the driving water discharged from the eductor, and returns the driving water in the tank to the eductor via a circulation line. A steam condensing device comprising a circulation pump, a drive water cooling heat exchanger provided in the circulation line, and a vent for discharging non-condensable gas from the tank. 2. The steam condensing device according to claim 1, wherein the eductor is provided within the tank, and a driving water outlet of the eductor is located in water within the tank. 3. The steam condensing device according to claim 1, wherein the eductor is provided outside the tank, and the driving water discharged from the eductor is guided into water inside the tank through a pipe. 4. The tank is provided with a baffle plate for lengthening the residence time of the non-condensable gas rising in the water in the tank, as set forth in claim 1, 2 or 3. steam condensing equipment.