JPS6158722B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drain recovery device that pumps condensate generated in steam-using equipment or the like to a boiler.

Conventionally, hot water was mixed with cold water in a water supply tank to lower the temperature, and then the water was pumped to the boiler using a water supply pump. However, due to the cavitation of the pump, only relatively low-temperature water could be sent. Ta. In addition, a circulation passage connecting the discharge port and suction port of the water supply pump was installed, and an ejector was interposed therebetween to suck in condensate, thereby increasing the pressure at the pump suction port to prevent cavitation of the pump. However, there were problems in that it was difficult to control and the pump efficiency was extremely low.

An object of the present invention is to provide a drain recovery device with a simple structure that can pump condensate to a boiler or the like with high pump efficiency without causing cavitation in the water supply pump. The drain recovery device according to the present invention has an ejector placed between the water supply pump and the boiler, sucks condensate from steam-using equipment, etc., and sends it under pressure to the boiler, etc. A connecting bypass passage is provided, and make-up water is pumped through the bypass passage to compensate for the lack of condensate recovery through the ejector. Therefore, according to the present invention, high-temperature condensate is sucked into the ejector on the downstream side of the water supply pump, and since the water supply pump only pumps low-temperature make-up water, cavitation does not occur, and the system has a circulation path through the ejector. The high-temperature condensate is drawn in by a simple ejector with no moving parts, and the shortfall in condensate recovery through the ejector is compensated for by pumping make-up water through the bypass passage. supplemented and water supply is reliable. Furthermore, as described above, since condensate recovery through the ejector is performed with priority over make-up water through the bypass passage, heat recovery efficiency is also high.

Next, the illustrated embodiment will be described in detail. Boiler 1
When the water level is between the high water level UL and the medium water level ML as shown in the figure, the signal from the water level detector 2 indicates that the water tank 3
A water supply pump 5 disposed in a pressure feeding passage 4 communicating with the boiler 1 is driven, and make-up water is forced into the ejector 6. At this time, an electrically operated on-off valve 8 in a passage 7 that connects the water supply pump 5 and the boiler and bypasses the ejector 6 is closed. In addition, water supply pump 5
In this embodiment, the boiler is always operated when the boiler water level is lower than the high water level UL. Therefore, steam generated in the boiler 1 and transported through the transport pipe 9 becomes condensate in the steam-using equipment 10, is selectively discharged in the steam trap 11, is introduced into the drain tank 12, and is further , suction port 1 of ejector 6
3, is sucked into the jet stream of make-up water pumped by the water supply pump 5, and is pumped from the day user 14 to the boiler 1. Here, the check valve 15 is used to prevent backflow from the boiler 1 to the ejector 6, the check valve 16 is used to prevent backflow from the ejector 6 to the water supply pump 5, and the check valve 17 is used to prevent backflow from the ejector 6 to the drain tank 12. It is mediated. Part of the re-evaporated steam in the drain tank 12 may be discharged to the water supply tank 3 or the like in order to create a pressure difference before and after the steam trap 11. When the amount of condensate recovered is less than the amount of evaporation in the boiler 1, the water level in the boiler 1 gradually decreases. When the boiler water level drops to the low water level LL, the on-off valve 8 is opened in response to a signal from the water level detector 2, and a portion of the make-up water pressurized by the feed water pump 5 is sent to the boiler 1 through the bypass passage 7. It can be done. When the boiler water level rises to the intermediate water level, the on-off valve 8 is closed again by a signal from the liquid level detector 2, and only condensate water recovery through the ejector 6 is performed. If the recovery amount increases, the boiler water level will be in a state between the high water level UL and the medium water level ML as shown in the figure. In this way, the water supply pump 5 is connected to the water supply tank 3.
Cavitation does not occur because only make-up water is pumped, and the pump efficiency is high because water passing through the ejector is not circulated.Also, since the bypass passage 7 is opened only at abnormally low water levels in the boiler 1, condensate recovery through the ejector 6 is possible. It is preferentially carried out, has a good heat recovery rate, and has a simple structure.

[Brief explanation of the drawing]

The figure is a schematic diagram of a drain recovery device according to an embodiment of the present invention. 1 is a boiler, 2 is a water level detector, 5 is a water supply pump, 6 is an ejector, 10 is a steam-using device, 11 is a steam trap, 7 is a bypass passage, 8 is an electrically operated on-off valve, 12 is a drain tank, 15 ,1
6 and 17 are check valves.

Claims (1)

[Claims] 1. An ejector is placed between the water supply pump and the pressure destination such as a boiler, and the ejector sucks condensate from steam-using equipment, etc. and pumps it to the pressure destination such as the boiler, and then between the water supply pump and the pressure destination such as the boiler. A drain recovery device characterized in that an ejector bypass passage is provided to connect the ejector, and make-up water is pumped through the bypass passage to a destination such as a boiler to compensate for the shortage of condensate recovery through the ejector.