JPS6016802Y2 - Two-stage pressure type exhaust gas economizer - Google Patents

Description

[Detailed description of the invention] This invention relates to a two-stage pressure type exhaust gas economizer, and its purpose is to increase the amount of high-pressure steam generated for driving turbines, etc., and at the same time to increase the amount of high-pressure steam generated for driving turbines, etc. The aim is to measure waste heat recovery.

Exhaust heat recovery by an exhaust gas economizer has conventionally been carried out using a single-stage pressure system.

A typical system is shown in FIGS. 1 and 3.

That is, in these, a steam superheating heat exchanger tube group 2 and a steam generation heat exchanger tube group 3 are arranged in order from the inlet side in the exhaust gas passage 1, and these heat exchanger tube groups 2 and 3 are used to separate steam and water common to both. connected to device 4.

Therefore, the can water in the steam water separator 4 is sent to the steam generation heat transfer tube group 3 by the can water circulation pump 5, where the waste heat is recovered and turned into steam and returned to the steam water separator 4.

Next, a part of this steam passes through the steam superheating heat exchanger tube group 2, is superheated by high-temperature exhaust gas, and is then used as a high-pressure working fluid for the turbine 6 and the like.

The other part of the steam is sent to the heating equipment 7 as a heat source for oil, water, etc. without being overheated and is used at low pressure.

The fluid discharged from the turbine 6 and the like passes through a condenser 8 and is collected into a drain tank 10 by a condensate pump 9.

Further, drain discharged from the heating equipment 7 is also collected in the drain tank 10.

Then, the hot water collected in the drain tank 10 is again supplied to the steam water separator 4 by the water supply pump 11.
The amount of water supplied is controlled by a water supply control valve 12 so as to keep the water level of the steam/water separator 4 constant.

In the system shown in FIG. 3, a feed water heater 13 is provided in order to increase the amount of boiling water evaporated or to reduce the heat transfer area of the steam generation heat transfer tube group 3. In order to preheat the feed water by the circulation can water heading towards the steam generation heat exchanger tube group 3, and to control the amount of evaporation within the steam generation heat exchanger tube group 3, the circulation can water temperature control valve 14 and the feed water heater 13 are used. A bypass path 15 is provided for.

Therefore, in the system shown in FIG. 1, the exhaust gas temperatures T□, T2. T3, and the steam temperature T at the inlet and outlet of each heat exchanger tube group 2, 3,
Th has a relationship as shown in FIG.

Further, in the system shown in FIG. 3, the relationship is as shown in FIG. 4.

In addition, in FIG. 4, t. indicates the inlet can water temperature of the steam generation heat exchanger tube group 3.

Comparing these two systems, both are single-stage pressure systems because the steam/water separator 4 is common to each of the heat exchanger tube groups 2 and 3.

On the other hand, in the system shown in FIG. 3, although it is possible to increase the amount of evaporation and to partially control it, the preheating of the water supplied to the steam-water separator 4 is circulated to the heat exchanger tube group 3 for steam generation. The method uses heat recovery from canned water, so
Exhaust gas temperature T.

It is impossible to make the temperature difference between the temperature Tc and the can water temperature Tc too large, or the temperature difference between the exhaust gas temperature T3 and the can water temperature Tc.

Therefore, there are limitations on recovering exhaust heat from the low-temperature region of the exhaust gas.

Furthermore, for the same reason, the amount of high-pressure steam generated is also limited in relation to the amount of evaporation.

The present invention has been devised in view of the above, and examples thereof will be described below with reference to FIGS. 5 and 6.

In FIG. 5, 20 is an exhaust gas passage, and this passage 20
A heat exchanger tube group 21 for steam superheating, a heat exchanger tube group 22 for high-pressure steam generation, and a heat exchanger tube group 23 for low-pressure steam generation are arranged inside in this order from the inlet side.

The high-pressure steam generation heat exchanger tube group 22 is connected between the liquid phase part and the gas phase part of a dedicated high-pressure side steam-water separator 24, and a canned water circulation pump 25 is interposed on the inlet side thereof.

On the other hand, the low-pressure steam generation heat transfer tube group 23 is connected between the liquid phase part and the gas phase part of the low-pressure side steam separator 26 dedicated for it, and a can water circulation pump 27 is installed in the can water circulation pipe 28 on the inlet side. is forced to intervene.

29 is a drain tank, and a water supply pump 31 and a water supply adjustment valve 32 are interposed in a water supply pipe 30 leading from the drain tank 29 to the high pressure side steam water separator 24, and this water supply pipe 3
0 and the can water circulation pipe 28 is provided with a feed water heater 33.

Further, a bypass pipe 34 for the feed water heater 33 is attached to the can water circulation pipe 28, and a circulating can water temperature control valve 35 is interposed at the connection between the bypass pipe 34 and the can water circulation pipe 28.

Note that the bypass pipe 34 may be attached to the water supply pipe 30 side.

The water supply pipe 30 has a low pressure water supply pipe 3 on the inlet side of the water supply heater 33.
6 is branched and connected, and a water supply control valve 37 is interposed therebetween.

Note that this low-pressure water supply pipe may be branched from the outlet side of the feed water heater 33.

The steam superheating heat exchanger tube group 21 has an inlet connected to the gas phase portion of the high-pressure side steam separator 24 and an outlet connected to the turbine 38 .

The outlet of the turbine 38 is connected to the drain tank 29 via a condenser 39 and a condensate pump 40.

Further, the inlet of a heating coil 41 disposed in the liquid phase of the low pressure side steam separator 26 is connected to the gas phase portion of the high pressure side steam water separator 24 , and a pressure regulating valve 43 is connected to the connecting pipe 42 . is forced to intervene.

The opening degree of this pressure regulating valve 43 is automatically controlled according to the gas phase pressure of the low pressure side steam/water separator 26.

The outlet of the heating coil 41 is connected to the drain tank 29.

On the other hand, a low pressure steam pipe 45 leading to various heating devices 44 is connected to the gas phase portion of the low pressure side steam/water separator 26.

Further, the drain of the heating equipment 44 is configured to be led to the drain tank 29.

When such a system is used for marine purposes, the exhaust gas G
is the exhaust gas from the main diesel engine, and the drum of the auxiliary boiler also serves as the high pressure side steam/water separator 24.

Therefore, when the diesel engine is stopped, steam is retained in the high-pressure steam separator 24 by operating the burner of the auxiliary boiler.

Furthermore, heating equipment 44 refers to equipment for heating oil, water, etc. inside the ship.

According to this system, superheated steam (temperature th) generated in the steam superheating heat exchanger tube group 21 is provided as a working fluid for the turbine 38, and is then collected in the drain tank 29 via the condenser 39 and the condensate pump 40. Ru.

Also, part of the steam (temperature 1.) in the high-pressure side steam separator 24 is sent to the steam superheating heat exchanger tube group 21, and the other part is sent to the heating coil 41 via the connecting pipe 42. After heating the liquid phase in the low pressure side steam separator 26, the drain tank 2
It will be collected on 9th.

Air is supplied to the heating coil 41 from the high-pressure side steam separator 24 when the diesel engine is stopped.

That is, when the diesel engine is stopped, steam is generated in the high-pressure side steam/water separator 24 by operating the auxiliary boiler, but the steam pressure in the low-pressure side steam/water separator 26 decreases as the output of the diesel engine decreases.

Therefore, due to this decrease in steam pressure, the pressure regulating valve 43 is operated, and high temperature steam is sent to the heating coil 41.

If the heating coil 41 in the low-pressure steam separator 26 is omitted, the steam pressure will decrease as the output of the diesel engine decreases, and the water temperature in the circulation tank will also decrease, causing the heat exchanger tube group for low-pressure steam generation to decrease. 23 drops below the dew point temperature of the sulfur content in the exhaust gas G, causing low-temperature corrosion.

Furthermore, while the diesel engine is stopped, the inside of the low-pressure side steam-water separator 26 is cooled by natural heat radiation and becomes vacuum, making it difficult to start up the canned water circulation pump 27 and to operate it normally.

In addition, the circulating can water sent to the low-pressure steam generation heat transfer tube group 23 has a low temperature Tr because the feed water heater 33 preheats the water fed to the high-pressure side steam-water separator 24 and recovers the heat.

Therefore, according to such a two-stage pressure system, in the heat exchanger tube group 23 for low-pressure steam generation, the lower temperature region of the exhaust gas G (
Since heat recovery at the temperature T3) becomes possible and the supply water on the high-pressure side is preheated by the circulating water on the low-pressure side, the amount of steam generated in the high-pressure steam generation heat exchanger tube group 22 increases.

The exhaust gas temperature curve and steam temperature in such a system have a relationship as shown in FIG.

As is clear from the above explanation, according to the present invention, a group of heat exchanger tubes for steam generation and a steam separator are provided on the high pressure side and the low pressure side, respectively, and the water supplied to the high pressure side steam separator is supplied with low pressure steam. Since it is preheated by heat exchange with the circulating tank water to the generation heat exchanger tube group, the amount of steam generated in the high pressure steam generation heat exchanger tube group increases, and heat recovery in the lower temperature region of the exhaust gas is possible. It can be measured.

Furthermore, as shown in the illustrated example, by providing a bypass pipe and a circulation tank water temperature control valve, it is possible to easily control the evaporation ratio on the high-pressure side and low-pressure side, and also to separate the steam and water on the high-pressure side and the low-pressure side. Even if the amount of water supplied to the vessel suddenly changes, there will be almost no fluctuation in the liquid level in the high-pressure side steam separator, and even if fluctuations occur in the low-pressure side steam separator, no problem will occur.

[Brief explanation of the drawing]

1 and 3 are explanatory diagrams of a conventional example, and FIGS. 2 and 4 are temperature diagrams for the systems shown in FIGS. 1 and 3, respectively. FIG. 5 is an explanatory diagram of a system according to an embodiment of the present invention, and FIG. 6 is a temperature diagram thereof. 20... Exhaust gas passage, 22... Heat transfer tube group for high pressure steam generation, 23... Heat transfer tube group for low pressure steam generation, 24... High pressure side air Water separator, 25...
... High pressure side can water circulation pump, 26 ... Low pressure side steam water separator, 27 ... Low pressure side can water circulation pump, 28 ... Can water circulation pipe, 30. ... Water supply pipe, 33 ... Water heater, G ... Exhaust gas, T□, T2. T3. To...Exhaust gas temperature,
tstt1? tr...Steam temperature.

Claims (1)

[Claim for Utility Model Registration] A high-pressure side steam-water separator, a low-pressure-side steam-water separator, and a steam superheating heat exchanger tube group whose inlet is connected to the gas phase section of the high-pressure side steam-water separator and whose outlet is connected to the turbine. , a group of high-pressure steam generation heat transfer tubes whose inlets are connected to the liquid phase section of the high-pressure side steam-water separator and whose outlets are connected to the gas-phase section of the separator; and whose inlets are connected to the gas-phase section of the high-pressure side steam-water separator. a heating coil arranged in the liquid phase section of the low-pressure side steam-water separator; a group of heat exchanger tubes for generating low-pressure steam, low-pressure steam pipes from the gas phase section of the low-pressure side steam/water separator to the heating equipment, a drain tank that collects condensate from the turbine, heating coil, and heating equipment, and a drain. A water supply pipe leading from the tank to the high pressure side steam water separator, a feed water heater interposed between the water supply pipe and the can water circulation pipe, a bypass pipe for the feed water heater attached to the water supply pipe or the can water circulation pipe, It is equipped with a low-pressure water supply pipe that branches from the water supply pipe and reaches the low-pressure side steam separator, and in the exhaust gas passage, a group of heat transfer tubes for steam superheating, a group of heat transfer tubes for high-pressure steam generation, and a group of heat transfer tubes for low-pressure steam generation are installed in the exhaust gas passage in order from the inlet side. Two-stage pressure type exhaust gas economizer-0 characterized by the arrangement of a group of heat tubes