JPH045461A - Waste heat recovering device for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve total efficiency of system by inserting not only a heat reclaimer from cooling water and a heat reclaimer from exhaust gas but also a heat reclaimer from lubricating oil into the circulating circuit of the waste heat recovering heat medium from an internal combustion engine. CONSTITUTION:At the time of operation, the waste heat recovering heat medium of a circulating circuit 7 is increased in temperature by the heat exchange from lubrication oil in a heat exchanger 12, further increased in temperature by the heat exchange from engine cooling water in a heat exchanger 4, and finally increased in temperature by the heat exchange from the exhaust gas having the highest temperature in a heat exchanger 5, and releases the resulting heat in an absorption type refrigerator 3 which is a recovered heat utilizing equipment to operate the refrigerator. The lubricating oil passed through the heat exchanger 12 is further cooled by an oil cooler 8 and returned to an internal combustion engine 1, and the heat of the cooling heat medium is released to the atmosphere from a cooling tower 11. Thus, the calorific value effectively used in the absorption type refrigerator 3 is increased, while the calorific value released to the atmosphere from the cooling tower 11 is reduced, resulting in an improvement in total efficiency of the system.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a waste heat recovery device for recovering and reusing heat generated by an internal combustion engine.

<Conventional technology> It is widely practiced to recover and reuse the heat generated by internal combustion engines, but in the past, recovery from cooling water and exhaust gas were performed separately, or as shown in Figure 2. It was common to use a combination of the two.

FIG. 2(a) shows an example of a so-called co-energy system in which a generator is driven by an internal combustion engine. In the figure, 1 is an internal combustion engine, 2 is a generator, 3 is a recovery heat utilization device such as an absorption chiller, 4 is a heat exchanger from cooling water, 5 is a heat exchanger from exhaust gas, and 6 is a cooling water The circulation circuit 7' is a circulation circuit for a heat medium for waste heat recovery, and the lubricating oil is indirectly cooled by cooling water. Note that this method of recovering waste heat from both cooling water and exhaust gas is disclosed in, for example, JP-A-59-
It is described in Publication No. 176452.

Furthermore, as shown in Fig. 2(b), the lubricating oil is cooled independently in a separate system, where 8' is an oil cooler for cooling the lubricating oil, 9' is a lubricating oil circulation circuit, and 10 ' is a circulation circuit for a cooling heat medium, and 11 is a cooling tower.

<Problems to be Solved by the Invention> Figure 3 illustrates the relationship between the usage time and deterioration of lubricating oil using the usage temperature as a parameter, and the vertical axis is T B N () - Tal base based on the HCl method.・Number). As you can see from this figure, if the oil temperature is 85℃, 1
Even after 1,000 hours, the TBN is around 4 and the deterioration after that is extremely gradual, whereas at 100-105℃
The deterioration is progressing rapidly, and there is a considerable difference between the two.

In the case shown in Figure 2 (,) above, the lubricating oil is often insufficiently cooled and the temperature of the lubricating oil rises to a temperature where deterioration rapidly progresses as explained in Figure 3. Problems such as having to change the oil frequently are likely to occur. Also, if the lubricating oil is cooled in a separate system as shown in Figure 2(b),
Although the temperature rise of the lubricating oil will be lower and the problem of deterioration will disappear, the temperature of the heat transfer medium from which heat is exchanged from the lubricating oil is low, so it is not suitable for using the recovered heat, so it is either disposed of as is as shown in Figure 1, or
Even if they were used, their value would be extremely small, and in any case, another problem would arise: the overall efficiency of the system would be low.

To illustrate the above problem with a numerical example, the lubricating oil temperature and overall efficiency in a cogeneration system of the same capacity are shown in Figure 2 (a).
In the method of 108℃ and 77.6%, respectively, the same figure (b)
The result is 87℃ and 74.2% in the method (a), but the overall efficiency is high, but the lubricating oil is prone to deterioration, and (b), the lubricating oil is hard to deteriorate, but the overall efficiency is low. -ing

The present invention has focused on these problems and has been made with the aim of improving the overall efficiency of the system while suppressing the temperature rise of the lubricating oil.

〈Means for solving problems〉 In order to achieve the above objectives, this invention.

In addition to a heat recovery device from cooling water and exhaust gas, a heat recovery device from lubricating oil is also inserted in the circulation circuit for heat medium for waste heat recovery from an internal combustion engine.

<Operation> Since the lubricating oil is directly cooled by the heat medium for waste heat recovery, the lubricating oil temperature does not rise to a temperature at which it is likely to deteriorate. Moreover, since the heat recovered from the cooling water and exhaust gas is added to the heat recovered from the lubricating oil, the temperature of the heat medium for waste heat recovery becomes higher than before, increasing the waste heat recovery rate and improving the system efficiency. Overall efficiency is improved.

<Example> Next, an example of the present invention shown in FIG. 1 will be described. Although this embodiment is an example of a system in which a generator is driven by an internal combustion engine similar to that shown in FIG. 2, the present invention is applicable to systems other than such a cogeneration system.

In Fig. 1, 1 is an internal combustion engine, 2 is a generator, 3 is a recovery heat utilization device, 4 is a heat exchanger from engine cooling water, 5 is a heat exchanger from exhaust gas, and 6 is a circulation of cooling water. The circuit 11 is a cooling tower as in FIG. 2, and the recovery heat utilization device 3 is, for example, an absorption refrigerator.

7 is a circulation circuit for a heat medium for waste heat recovery; 8 is an oil cooler equipped with a heat exchanger from lubricating oil; 9 is a circulation circuit for lubricating oil;
10 is a cooling heat medium circulation circuit, 12 is a heat exchanger provided according to the present invention, and the lubricating oil circulation circuit 9 is configured to pass through this heat exchanger 12 and the oil cooler 8, and waste heat is The recovery heat medium circulation circuit 7 includes a heat exchanger 12,
The heat medium is configured to circulate in this order via the heat exchanger 4 and the heat exchanger 5. Reference numeral 13 denotes an intercooler, and the cooling heat medium circulation circuit 10 is configured to pass through the intercooler 13 and the oil cooler 8. 14.15 and 16 are circulation pumps, 17 and 1
8 is a switching valve.

In addition, water is generally used as the heat medium for waste heat recovery in the circulation circuit 7 and the heat medium for cooling in the circulation circuit 10, and in that case, they are called secondary cooling water and tertiary cooling water, respectively, with respect to engine cooling water. may be done.

This embodiment is constructed as described above, and during operation, the heat medium for waste heat recovery in the circulation circuit 7 is first heat-exchanged from the lubricating oil in the heat exchanger 12 to raise its temperature, and then transferred to the heat exchanger 4. Heat is exchanged from the engine cooling water and the temperature rises further.Finally, heat is exchanged from the exhaust gas with the highest temperature in the heat exchanger 5, and the temperature rises further.The absorption chiller 3, which is a recovery heat utilization device, uses this heat. is released to operate the refrigerator. Furthermore, the lubricating oil that has passed through the heat exchanger 12 is further cooled by the oil cooler 8 and returns to the internal combustion engine 1, and the heat of the cooling heat medium is released from the cooling tower 11 to the atmosphere.

In this way, the heat medium for waste heat recovery also recovers heat from the lubricating oil, so the heat recovered from the cooling water and exhaust gas in heat exchangers 4 and 5, respectively, is added to this recovered heat, and the waste heat is The temperature of the heat medium for heat recovery becomes higher than before. Therefore, while the amount of heat effectively used by the absorption type cold N generator 3 increases, the amount of heat released to the atmosphere by the cooling tower 11 decreases, and the overall efficiency of the system is improved.

By the way, to give a numerical example of the lubricating oil temperature and overall efficiency in the case of this method, in a system with the same capacity as the conventional method mentioned above, the values are 85°C and 76.0%, respectively, which shows that the lubricating oil temperature can be kept low. However, the effect of this invention is shown in that high overall efficiency can be obtained.

<Effects of the Invention> As is clear from the above description, the present invention is applicable to a circulation circuit for a heat medium for recovering waste heat from an internal combustion engine.

This system incorporates a heat recovery device from lubricating oil, a heat recovery device from cooling water, and a heat recovery device from exhaust gas, and prevents the lubricating oil temperature from rising to a high temperature that is likely to cause deterioration. This makes it possible to increase the heat recovery rate and improve the overall efficiency of the system.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG.
) and FIG. 2(b) are block diagrams of the conventional example, and FIG. 3 is a diagram showing the relationship between usage time and deterioration of lubricating oil. 1... Internal combustion engine, 2... Generator, 3... Recovery heat utilization machine N (absorption chiller), 4, 5, 12... Heat exchanger, 6... Cooling water circulation Circuit, 7... Circulation circuit for heat medium for waste heat recovery, 9... Circulation circuit for lubricating oil. Patent applicant Yanmar Diesel Co., Ltd. Agent
Patent Attorney Shino 1) Actually Figure 2 (a)! 1Pj1 Figure 2 Figure (b) Figure 3

Claims (1)

[Claims] (1) In the circulation circuit of the heat medium for waste heat recovery from the internal combustion engine,
A waste heat recovery device for an internal combustion engine, characterized in that a heat recovery device from lubricating oil, a heat recovery device from cooling water, and a heat recovery device from exhaust gas are inserted.