JPS60259802A - Waste-heat recovery heat pump system of marine diesel main engine - 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 1. Field of Industrial Application The present invention relates to a system for recovering a high-temperature, highly useful heat source from a relatively low-temperature waste heat source in a diesel propulsion plant for a ship or the like.

R Conventional Technology In a diesel propulsion plant for a ship, heat from the exhaust gas is conventionally recovered by an economizer to generate steam to drive a turbine generator, thereby providing the necessary electricity on board the ship during the voyage.

In this case, when the exhaust gas temperature falls below the dew point of sulfuric acid, sulfurous acid in the exhaust gas condenses as sulfuric acid, corroding the materials in contact with the gas. Therefore, the water supplied to the economizer needs to be heated above 130°C, which is the dew point of sulfuric acid, and for this reason, the water is extracted from an appropriate temperature in the intermediate stage of the turbine, which is driven by the steam generated by the economizer. ,
The steam heats the water supply.

FIG. 2 shows a conventional general exhaust gas power generation system. I
0 is an exhaust gas economizer, through which the exhaust gas of the diesel engine passes in the direction of the arrow, and passes through the superheated section 15. of the economizer 10 in order from the high temperature side. Evaporation section 14. A preheating section 13 is arranged. The steam generated here drives the turbine 1 and the direct-coupled generator 16, and then becomes condensed water in the condenser 2 by cooling with seawater. This condensate is sent to the feed water preheater 5a by the condensate pump 3, where it is heated to about 130° C. or higher, which is the dew point of sulfuric acid, by steam extracted from the intermediate stage of the turbine 1. This high-temperature water is sent to the preheating section 13 of the economizer 10 by the water supply pump 9 and then to the evaporation section.

After passing through the superheating section, it becomes steam again and circulates.

C.9 Problems to be Solved by the Invention In the prior art described above, feed water is heated by extraction air, and this steam does not participate in turbine drive. Therefore, if possible, it is desirable to heat the feed water using another heat source to increase the turbine output.

In addition, energy saving has recently been strongly advocated, and the efficiency of diesel engines has improved significantly, and the exhaust gas temperature at the outlet of the two engines has tended to decrease. On the other hand, the rise in fuel costs has led to an increase in the use of inferior fuels such as C heavy oil.

As these fuels have relatively high sulfur content.

(3) The dew point of sulfuric acid in exhaust gas is also on the rise.

Therefore, a decrease in the economizer inlet gas temperature and an increase in the economizer outlet gas humidity tend to decrease the recovered energy, and from this point of view as well, it is a problem that is required to increase the turbine output.

Means for solving the 20-year condylar point In a marine diesel propulsion plant, in addition to the exhaust gas heat recovered by the economizer mentioned above, the heat of the cylinder jacket cooling water, the compressed air heat at the turbocharger outlet, and the lubricating oil heat are used. etc. These are not very hot, so they are usually cooled with seawater.

That heat is dumped overboard.

The present invention divides these relatively low-temperature waste heat into a portion that is used as is at low temperature and a portion that is used to obtain a high heat source using a heat pump, depending on the temperature level,
The heat pump system itself uses the same working medium as the medium of the power generation system, and as a result, it is a direct contact type that allows both media to mix and come into contact, resulting in high heat exchange efficiency and compactness of the device (4). It uses a condenser to effectively recover waste heat with the addition of a small amount of power.

E. Embodiment FIG. 1 shows an embodiment in which the present invention is applied to a marine economizer power generation plant. In the same figure, tfl, t, ... ta,
T+...T4 indicates the temperature of the fluid at that portion.

The steam generated by the exhaust gas economizer is sent to the turbine l at a temperature to to drive the generator 16. The steam leaving the turbine 1 reaches the condenser 2.

It is cooled by seawater and condensed, and the condensate pump 3 lowers the temperature to t2=
It is sent to the heat exchanger 4 at about 35°C.

The cylinder jacket cooling water is heated in the cylinder and enters the heat exchanger 4 at Tl=80°C, so the condensate is heated to a temperature t3 of about 70°C and enters the direct contact condenser 5. . Here, high-pressure, high-temperature steam is sent from the compressor 8 at a temperature t7, contacts and mixes with the condensate, and is condensed to become hot water at about 140° C., which is sent to the economizer preheating section by the water pump 9.

A portion of the hot water condensed in the condenser 5 expands through the pressure reducing valve 6, is heated in the heat exchanger 7 by the supercharger outlet air Ta = approximately 120°C, and is vaporized into steam at a temperature of approximately t6-110°C. The air is then sucked into the compressor 8, where the pressure is increased to a temperature t7, and the air enters the condenser 5, returning to the cycle described above.

Heat exchanger? A part of the low-pressure steam generated can be directly sent to the low-pressure section of the turbine 1 and used for power generation without passing through an economizer, or can be used as miscellaneous steam for heating fuel oil onboard the ship.

As shown in FIG. 8, the heat exchanger 7 has a high temperature part 7a and a low temperature part 7a for waste heat. Divide the water from heat exchanger 4 into 7b.
After raising the temperature through the heat pump, it is sent to the condenser.

Alternatively, the high temperature section 7a may be used only as an evaporation section to make the evaporation temperature as high as possible. There are other waste heat sources, and their combinations are not limited to those listed above. Among waste heat sources, those with relatively low temperatures are used to directly heat the water supply, and those with high temperatures are used in the evaporation section of the heat pump system. It is preferable.

The above explanation was about a marine diesel propulsion plant, but this system can of course also be applied to land-based chemical plants, industrial plants, etc.
There are many types of waste heat sources depending on their characteristics, and the routes to high heat sources after recovery are also diverse, but these multi-source waste heat sources can be combined.

By applying a heat pump system that uses a direct contact condenser as in the case of the marine vessel described above, it is possible to recover and utilize the available high-temperature heat source from the relatively low-temperature waste heat source.

3 Effects of the Invention The only additions to the prior art in the present invention are a compressor and a condenser, but the condenser is a direct contact type condenser in which the working medium of the heat pump and the working medium of the power generation system are the same. The structure is simple, compact, and inexpensive. In addition, the heat pump system has an evaporation temperature ta and a condensation temperature t4.
When , the coefficient of performance εh = t4/(t4- ta
), the smaller the difference between t4 and 76, the more advantageous it is, but in the case of the present invention, it is 5 or more.

(7) Depending on the method, a coefficient of performance of 8 to 9 can be expected, and the power required for the compressor is small compared to the waste heat recovery energy obtained.

In other words, relatively low-temperature waste heat that was conventionally discarded can be recovered as a high-temperature heat source using a heat pump system that has fewer components and is simpler and cheaper than a general heat pump, and has a high coefficient of performance and consumes less power. This heats the exhaust gas economizer feed water, which was conventionally heated by bleed steam. Furthermore, the low-pressure steam generated in the evaporation section of the heat pump system can be guided to the turbine low-pressure section to increase the amount of power generation, or can be used as miscellaneous steam.

[Brief explanation of drawings]

FIG. 1 is a system diagram according to an embodiment of the present invention, FIG. 2 is a system diagram according to the prior art, and FIG. 3 is a system diagram of an embodiment of the present invention different from that shown in FIG. ■... Steam turbine, 2... Condenser, 8... Condensate pump, 4... Heat exchanger, 5... Direct contact condenser (8) 5a... Feed water heater , 6...expansion valve? ...Heat exchanger, 7a...High temperature section, 7b...Low temperature section, 8...
Compressor, 9... Water supply pump, 10... Exhaust gas economizer, 11... Evaporation drum, 12... Circulation pump. 13... Preheating section, 14... Evaporation section, 15... Superheating section. 16... Generator patent applicant Mitsui Engineering & Shipbuilding Co., Ltd. Figure 1 T3 T4 TI T2

Claims (1)

[Claims] In a power generation system that utilizes exhaust gas heat from marine diesel main machinery, a heat pump system that uses the same working medium as the power generation system and a direct contact condenser,
Relatively low-temperature waste heat sources from diesel main machinery are combined according to their temperature levels, recovered as a high-temperature heat source, and used to heat the economizer feed water of the power generation system. 1 Waste heat recovery heat pump system for marine diesel main machinery, characterized in that part of it is guided to the turbine low pressure part of the power generation system and recovered as motive power or used as miscellaneous steam