JPS60155802A - Economizer for exhaust gas - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust gas economizer that recovers heat from high-temperature exhaust gas.

For example, a tea cell engine (
Hereinafter referred to as the "Teesel main engine". ) exhaust gas economizer 2 is connected to the exhaust gas outlet of the tea cell main engine 1, as shown in Fig.
, a high pressure evaporation section 4, a low pressure evaporation section 5, and a preheating section 6.

For water supply, low-pressure saturated water after brackish water separation in a low-pressure brackish water separator 11 is led to an atmospheric pressure drain tank 7 and heated to approximately 90°C.
After being heated to , the water is guided by the water supply pump 8 to the preheating section 6 of the exhaust gas economizer. Here, the feed water is heated to near the saturation temperature of the low-pressure evaporator 6, and then guided to the auxiliary boiler 9, which serves as a brackish water separator of the high-pressure evaporator 4, and the low-pressure evaporator 5.

The feed water led to the low-pressure evaporator 5 is taken out as a brackish water mixture, and the brackish water is separated in a low-pressure brackish water separator 11, and the steam is supplied to an onboard service steam usage site 15 for heating fuel oil, etc. - As mentioned above, the 17 liters is led to the large air tank 7 and used for heating the water supply.

On the other hand, the saturated water in the auxiliary boiler 9 is guided to the high-pressure evaporator 4 by the boiler water circulation pump 10 and taken out as a first brackish water mixture, and is returned to the steam tram of the auxiliary boiler where the brackish water is separated.

The steam from which the brackish water has been separated is led to the superheating section 3, heated to a predetermined temperature, and then supplied to the generator turbine 12, which is then used to drive the condenser 13 and condensate pump 1.
4 and returns to the atmospheric pressure drain tank 7.

In the above system, the feed water is led to the preheating section of the exhaust gas economizer at about 90° C., so the gas side surface temperature of the preheating section is in the low-temperature corrosion region. For this reason, although low-temperature corrosion-resistant steel is used for the preheating section tube, it still
Partial selective corrosion occurs in the region of ~120°C. As a countermeasure to this problem, overlay repair is performed only on the areas where selective corrosion has occurred to extend the service life, but the repair costs are considerable, and overlay repair itself is not a complete solution. Even if it is repaired once, it will corrode again after 3 to 4 years and will need to be repaired again. In addition, to reduce low-temperature corrosion, it is sufficient to raise the water supply temperature to the preheating section to 120°C or higher, but if a steam-type water heater is installed, steam is used for the water heater, so the power generation will be reduced accordingly. There is a shortage of steam for driving the machine turbine or on-board → novice steam, resulting in losses.Also, the amount of water supplied remains the same, but only the temperature of the supplied water increases, so the required amount of heat absorption in the preheating section decreases, and as a result, the amount of heat absorbed in the preheating section decreases. It is necessary to plug some of the tubes in the prefabricated version to reduce the heat transfer area.

In view of the above points, the present invention has been made with the following objectives: 1) To provide an exhaust gas economizer that increases the temperature of water supplied to the preheating section without substantially reducing the heat recovery rate and reduces low-temperature corrosion. It is characterized by comprising piping that communicates the outlet and inlet of the water supply heating element, and a recirculation pump interposed in the piping.

According to the present invention, by driving the recirculation pump, high-temperature feed water is supplied from the outlet to the inlet of the water supply heating section through the piping described in 1. Therefore, low-temperature corrosion of the water supply heating element is reduced, and the water supply flow rate of the water supply heating element increases due to circulation, so the amount of heat recovery does not decrease even if the inlet temperature increases by 1. Furthermore, it is possible to prevent low-temperature corrosion without affecting other equipment.

An embodiment of the present invention will be described below with reference to FIG. Components in FIG. 2 denoted by the same reference numerals as those in FIG. 1 have the same functions as those in FIG. 1, and a description thereof will be omitted.

The one in FIG. 2 is the same as the one in FIG. 1, but includes a recirculation line 19 for returning a portion of the high water at the outlet of the preheating section to the inlet of the preheating section and mixing it with the supply water. A recirculation pump 16, an orifice 17 for flow rate adjustment, and a needle valve 18 are added to the recirculation line 19. In the figure, water is supplied from the atmospheric pressure drain tank 7 to the preheating section 6 of the exhaust gas economizer 2 by the water supply pump 8, but the preheating section recirculation pump 16 is installed in the recirculation line 19 that communicates the outlet and inlet of the preheating section. A part of the preheated high-temperature water supply (140 to 150°C) is guided through the flow rate adjustment needle valve 18 and the orifice 17 to the preheating section inlet water supply line, and the water supply from the atmospheric pressure drain tank 7 (approximately 90 °C ℃), the water supply temperature at the inlet of the preheating section is raised to 120.degree.

The effects of the exhaust gas economizer as described above are as follows.

1) By connecting the water supply lines entering and exiting the preheating section with a recirculation pump, the temperature of the water supply at the entrance of the preheating section can be easily raised to a predetermined temperature without being affected by other factors, so the system is simple.

11) Even if the preheating section inlet water supply temperature is increased with the recirculation pump, the preheating section water supply amount (circulation amount) will increase, so the preheating section outlet water temperature will only be slightly lower than when the recirculation pump is not used. There is no need to cut the heat transfer area of the preheating section, and therefore the amount of waste heat recovered is almost 1"L.

111) With the above, the temperature of the water supply entering the preheating section can be raised to 120° C. or higher in a simple and effective manner, and low-temperature corrosion of the preheating section tube can be greatly reduced.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an example of a conventional exhaust gas economizer, and FIG. 2 is a system diagram of an embodiment of the present invention. ■... Tea cell main engine, 2... Exhaust gas economizer, 6... Preheating section, 16... Recirculation pump, 19...
・Recirculation line. 1 area of bamboo

Claims (1)

[Claims] An exhaust gas economizer characterized by comprising a pipe that communicates an outlet and an inlet of a water supply preheating section, and a recirculation pump installed in the pipe.