JP4324216B2 - Engine exhaust gas heat recovery unit and engine-driven heat pump or cogeneration system using the same - Google Patents

Description

  The present invention relates to an exhaust gas heat recovery device for an engine used in an engine-driven air conditioner, a cogeneration system, or the like.

Conventionally, as an exhaust gas heat recovery device for an engine, a configuration in which a baffle plate is provided in an exhaust gas passage to restrict an exhaust gas flow to recover heat from the engine exhaust gas is known.
JP 2002-372394 A

  However, the conventional engine exhaust gas heat recovery unit is configured to restrict the exhaust gas by the baffle plate, and the heat transfer path is exhaust gas → baffle plate → heat transfer pipe or inner cylinder part (both of the engine coolant passage). Partition wall) → Engine cooling water. That is, the kinetic energy of the exhaust gas flow rate is lost and the exhaust heat recovery rate is reduced by the amount of the baffle plate between the exhaust gas and the partition wall of the engine coolant passage.

  Further, since the passage path of the exhaust gas is complicated by the baffle plate, the pressure loss of the passage path of the exhaust gas increases or the condensed water tends to stay. In particular, depending on the engine, there is a concern that when nitrogen oxides in the exhaust gas stay, they aggregate to form nitric acid and corrode the exhaust gas passage.

  The present invention has been made in view of such circumstances, and by causing the exhaust gas to directly collide with the partition wall of the engine cooling water passage without interposing a member between the exhaust gas and the partition wall of the engine cooling water passage. It aims at providing the structure which raises the gas flow rate of a heat exchange part and enables the further improvement of a waste heat recovery rate.

An engine exhaust gas heat recovery device according to the present invention for solving the above-described problems is an engine exhaust gas heat recovery that recovers heat from exhaust gas by exchanging heat between the exhaust gas from the engine and the engine coolant. in vessels, a plurality of injection holes for the partition wall of the coolant passage in the exhaust gas inlet pipe wall, a structure for guiding the entire amount of exhaust gas the occlusion is provided in the radial direction in the exhaust gas inflow side end of the exhaust gas inlet pipe, an exhaust A cooling water inlet is provided on the opposite side of the exhaust gas inlet in the gas inflow direction, the cooling water passage is provided to the exhaust gas inlet side, and the nozzle hole is provided from the exhaust gas inlet side to the cooling water in the exhaust gas inflow direction. It is provided up to the inlet side, and the entire amount of exhaust gas collides directly with the partition wall of the cooling water passage in the entire exhaust gas inflow direction . Further, in this engine exhaust gas heat recovery device, a cutout portion that allows gas to flow is provided at one or a plurality of locations of the catalyst support joined to the catalyst outer periphery.

  In the engine exhaust gas heat recovery device, the shortest distance from each nozzle hole to the partition wall of the cooling water passage is in the range of 1.5 to 7 times the nozzle hole diameter.

Further, in the engine exhaust gas heat recovery device, the relationship between the total opening area of each nozzle hole and the exhaust gas flow rate is (total nozzle hole area / exhaust gas mass flow rate) = 2.0 to 4.5 (cm ² / (kg / min).

  An engine-driven heat pump or cogeneration system according to the present invention for solving the above-described problems uses the engine exhaust gas heat exchanger in the exhaust gas path of the engine.

  As described above, according to the present invention, it is possible to improve the exhaust heat recovery efficiency.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an engine exhaust gas heat recovery device 1 according to the present invention, and FIG. 2 shows an example of a cooling water circuit diagram of a gas engine 10 provided with the engine exhaust gas recovery device 1.

  That is, the engine exhaust gas heat recovery device 1 is provided with a plurality of nozzle holes 20 in the outer pipe 22 of the exhaust gas inflow pipe 2 toward the inner tube 31 of the cooling water passage 3. It directly collides with the inner tube 31.

  As shown in FIG. 2, the engine exhaust gas heat recovery unit 1 is provided so that the exhaust from the engine 11 to the silencer 12 passes through the exhaust gas inflow pipe 2, and the cooling water of the engine 11 is cooled. It is provided to be introduced into the engine 11 after passing through the water passage 3. The cooling water after passing through the engine 11 is configured to circulate by a pump 13. Further, the temperature of the cooling water can be controlled by the thermostat 14, and the flow can be switched to the radiator 16 or the heat exchanger 17 by the three-way valve 15.

  The exhaust gas inflow pipe 2 has a double pipe structure of an inner pipe 21 and an outer pipe 22, and one end side of the inner pipe 21 serves as an inlet 21a into which exhaust gas flows.

  The inner pipe 21 is closed at a position immediately after flowing in from the exhaust gas inlet 21a at one end thereof, and an opening 21b is provided on the outer peripheral surface on the inflow proximal end side to the closed position. Therefore, the exhaust gas flows from the inlet 21a at one end of the inner tube 21 and passes through the opening 21b to the outer tube 22.

  The outer tube 22 is provided with a plurality of injection holes 20 at equal intervals along the longitudinal direction and the circumferential direction. Therefore, the exhaust gas that has passed from the opening 21 b of the inner tube 21 to the outer tube 22 is ejected from these nozzle holes 20.

  The cooling water passage 3 is configured to cover the entire exhaust gas inflow pipe 2 with a space S between the cooling water passage 3 and the exhaust gas inflow pipe 2.

  The cooling water passage 3 is composed of an inner cylindrical pipe 31 and an outer cylindrical pipe 32, and has a double pipe structure through which cooling water passes, and an exhaust gas inlet 21a of the exhaust gas inflow pipe 2 and A cooling water inflow pipe 33 is connected to the end face of the opposite outer cylinder pipe 32 on the other end side. In addition, a drain pipe 34 is connected to the outer peripheral surface on one end side of the outer tube 32 so that the cooling water flowing from the inflow pipe 33 and passing through the cooling water passage 3 can be drained from the drain pipe 34. Has been made. Further, an exhaust pipe 35 penetrating the inner cylinder pipe 31 and the outer cylinder pipe 32 is connected to the outer peripheral surface on the other end side of the cooling water passage 3, and the space S is formed from the injection hole 20 of the exhaust gas inflow pipe 2. The ejected exhaust gas can be exhausted from the exhaust pipe 35.

  According to the engine exhaust gas heat recovery device 1 configured as described above, the exhaust gas from the engine is injected from the opening 21b of the inner tube 21 through the outer tube 22 through the nozzle hole 20. Exhaust gas injected from the nozzle hole 20 is the only partition wall between the coolant and the coolant without being disturbed by other members and losing the kinetic energy of the gas flow rate. It is possible to inject directly into the inner tube 31 at a high ejection speed. Therefore, the cooling water passing through the cooling water passage 3 can recover the exhaust heat from the exhaust gas with high thermal efficiency.

  Further, the exhaust gas heat recovery device 1 can be made an extremely simple gas passage route without complicating the passage route of the exhaust gas by a member such as a baffle plate as in the prior art. It is possible to prevent stagnation and increase in pressure loss. Therefore, corrosion due to generation of condensed water or generation of nitric acid due to aggregation of nitrogen oxides can be prevented, and excellent durability can be obtained.

  In the present embodiment, the exhaust gas inflow pipe 2 of the engine exhaust gas heat recovery device 1 has a double pipe structure of an inner pipe 21 and an outer pipe 22, but in particular such a double pipe structure. The present invention is not limited to this, and the nozzle hole 20 may be provided directly in one exhaust gas inflow pipe 2 to further simplify the configuration.

  Further, in the present embodiment, the exhaust gas inlet 21a and the cooling water inflow pipe 33 are provided so as to face the end face of the engine exhaust gas heat recovery device 1, and the cooling water drain pipe 34 and the exhaust water are exhausted. The gas exhaust pipe 35 is provided at a position opposite to the outer peripheral surface of the engine exhaust gas heat recovery device 1. The most important thing in the present invention is that the exhaust gas from the nozzle hole 20 is cooled with the cooling water. Other than the above-described exhaust gas inlet 21a, cooling water inflow pipe 33, cooling water drain pipe 34, exhaust gas exhaust pipe 35, etc. The position for providing is not particularly limited, and may be appropriately changed.

  Further, in the present embodiment, the direction of the exhaust gas ejected from the nozzle hole 20 is perpendicular to the inner tube 31 serving as the partition wall, but is limited to ejecting in the perpendicular direction. It may be one that is ejected from an oblique direction.

  Fig. 3 shows that the pressure loss when using an exhaust gas heat recovery device with a baffle plate (part number 124593-13370 manufactured by Yanmar Co., Ltd.) as shown in the prior art for a gas engine (3GPG88 manufactured by Yanmar Co.) is 100% The relationship between the pressure loss of the exhaust gas heat recovery device 1 according to the present invention and the average heat passage rate (K value) when the average heat passage rate (K value) at that time is 100% is shown. About the pressure loss of the exhaust gas heat recovery device 1 which concerns on this invention, it adjusted by increasing / decreasing the number of the nozzle holes 20. As a result, the exhaust gas heat recovery device 1 according to the present invention has an average heat passage rate (twice or more that of the conventional one) even if the pressure loss is about 40 to 80% of the pressure loss by the conventional exhaust gas heat recovery device. K value) can be obtained, and it has been confirmed that the exhaust heat recovery rate can be improved.

  FIG. 4 shows a ratio (h / D) between the distance h to the inner tube 31 where the exhaust gas from the nozzle hole 20 is injected in the exhaust gas heat recovery device 1 according to the present invention and the diameter D of the nozzle hole 20. ) Is appropriately changed, and the relationship between this ratio (h / D) and average heat passage rate (K value) is shown. As for the average heat transfer rate (K value), as in the case of FIG. 3 above, the exhaust gas heat recovery device (part number 124593-13370 manufactured by Yanmar Co., Ltd.) using a baffle plate as shown in the prior art is used for the gas engine ( The average heat passage rate (K value) when used for Yanmar 3GPG88) was 100%.

  As a result, by maintaining this ratio (h / D) in the range of 1.7 to 7, the collision speed of the exhaust gas to the inner tube 31 can be maintained, and the exhaust heat recovery rate can be improved while the exhaust gas is exhausted. It was confirmed that an increase in gas pressure loss could be prevented. When this ratio (h / D) is less than 1.7, the exhaust gas pressure loss increases. Further, when this ratio (h / D) exceeds 7, an effect can be obtained, but it becomes impossible to obtain an average heat passage rate (K value) that is twice or more of the target of the related art.

  FIG. 5 shows this ratio and the average heat passage rate (K value) when the ratio between the total sum of the area of each nozzle hole 20 and the exhaust gas mass flow rate in the exhaust gas heat recovery device 1 according to the present invention is appropriately changed. And the relationship with exhaust gas pressure loss. As in the case of FIG. 3 above, the average when using an exhaust gas heat recovery device (part number 124593-13370 made by Yanmar) with a baffle as shown in the prior art for a gas engine (3GPG88 made by Yanmar) The heat passage rate (K value) and pressure loss were 100%.

  As a result, by keeping this ratio in the range of 2.0 to 4.5, the collision speed of the exhaust gas to the inner tube 31 can be kept appropriate, and the exhaust heat recovery rate (K value) can be improved. At the same time, it was confirmed that an increase in exhaust gas pressure loss could be prevented. If this ratio is less than 2.0, exhaust gas pressure loss will increase. Moreover, when this ratio exceeds 4.5, although an effect is acquired, it becomes impossible to obtain an average heat passage rate (K value) that is twice or more the target of the related art.

  In the present embodiment, the exhaust gas from the nozzle hole 20 is injected into the inner tube 31 of the cooling water passage 3, but the exhaust gas from the nozzle hole 20 flows through the passage through which the cooling water flows. The exhaust gas heat recovery unit 1 is not particularly limited to the exhaust gas heat recovery unit 1 as long as it can be directly injected onto the partition wall. For example, the exhaust gas heat recovery unit 1 as shown in FIG. 6 may be used. . That is, the exhaust gas heat recovery device 1 eliminates the outer pipe 22 of the exhaust gas inflow pipe 2, takes a large space S as a configuration of only the inner pipe 21, and includes cooling water flowing through the cooling water passage 3 in this space S. Similarly, a plurality of cooling water pipes 4 through which cooling water flows are provided, and exhaust gas from the nozzle holes 20 provided in the inner pipe 21 is injected into each cooling water pipe 4. In FIG. 6, the same members as those in the exhaust gas heat recovery device 1 shown in FIG.

  The present invention can be used as an exhaust gas heat recovery device for various engines used in air conditioners and cogeneration systems.

(A) is sectional drawing of the engine exhaust-gas heat recovery device based on this invention, (b) is the II sectional view taken on the line of the same figure (a). It is a cooling water circuit diagram of an engine provided with the engine exhaust gas heat recovery device shown in FIG. It is a graph which shows the relationship of the average heat passage rate with respect to the exhaust gas pressure loss of the engine exhaust gas heat recovery device which concerns on this invention. It is a graph which shows the relationship of the average heat passage rate with respect to the ratio of the distance to the inner cylinder pipe in which the exhaust gas from the nozzle hole of the engine exhaust gas heat recovery device which concerns on this invention is injected, and a diameter with a nozzle hole. It is a graph which shows the relationship of the average heat passage rate with respect to the ratio of the total nozzle hole area of the engine exhaust gas heat recovery device which concerns on this invention, and exhaust gas mass flow, and exhaust gas pressure loss. (A) is sectional drawing which shows other embodiment of the engine exhaust gas heat recovery device which concerns on this invention, (b) is the II-II sectional view taken on the line of the same figure (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine exhaust gas heat recovery device 2 Exhaust gas inflow pipe 20 Injection hole 3 Coolant passage 31 Inner cylinder pipe (partition)

Claims (4)

In an engine exhaust gas heat recovery device that recovers heat from exhaust gas by exchanging heat between exhaust gas from the engine and engine cooling water,
The exhaust gas inflow pipe peripheral wall is provided with a plurality of nozzle holes directed to the partition wall of the cooling water passage, the exhaust gas inflow pipe has a closed portion at the end of the exhaust gas inflow direction , and the exhaust gas inflow direction is guided in the radial direction. A cooling water inlet is provided on the opposite side of the exhaust gas inlet, the cooling water passage is provided up to the exhaust gas inlet side, and the nozzle hole extends from the exhaust gas inlet side to the cooling water inlet side in the exhaust gas inflow direction. The engine exhaust gas heat recovery device according to claim 1 , wherein the exhaust gas total amount is made to collide directly with the partition wall of the cooling water passage in the entire exhaust gas inflow direction .   The engine exhaust gas heat recovery device according to claim 1, wherein the shortest distance from each nozzle hole to the partition wall of the cooling water passage is in a range of 1.5 to 7 times the nozzle hole diameter. 2. The relationship between the total opening area of each nozzle hole and the exhaust gas flow rate is (total nozzle hole area / exhaust gas mass flow rate) = 2.0 to 4.5 (cm ² / (kg / min)). Engine exhaust gas heat recovery device.   An engine-driven heat pump or cogeneration system using the engine exhaust gas heat recovery device according to any one of claims 1 to 3 in an exhaust gas passage of the engine.

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