JP2019065744A - Waste treatment plant - Google Patents

Abstract

To reduce thermal loss in a waste treatment plant by giving/receiving heat between a fire grate and an internal combustion engine that are provided in the waste treatment plant and thus effectively use thermal energy.SOLUTION: A waste treatment plant 1 includes: a boiler 3 for generating steam by burning waste on a fire grate 9 provided in a combustion furnace 2; a steam turbine 4 driven by the steam generated by the boiler 3; a first power generator 7 generating power by using driving force of the steam turbine 4; a methane fermentation tank 5 generating methane-containing biogas from waste; a gas engine 6 driven by the methane-containing biogas from the methane fermentation tank 5; a second power generator 8 generating power by using the driving force of the gas engine 6; and a first coolant flow passage 31 connecting the fire grate 9 and the gas engine 6 and having a coolant flowing therein.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a waste treatment plant that generates electricity from steam generated by burning waste on a grate.

  Some waste treatment plants that process waste include a combustion furnace that burns while transferring waste on a grate. In a combustion furnace that burns waste on a grate, the grate is cooled by cooling water so that the heat of the flame burning the waste does not damage the grate.

  The cooling water cooled by heating the grate is cooled by the cooling tower and then used again for cooling the grate. For this reason, all the heat of the cooling water heated at the time of cooling of the grate is dissipated to the atmosphere through the cooling tower, and there is a problem that the waste disposal plant as a whole loses heat. For this reason, it was desired to use the heat of the cooling water heated at the time of cooling of the grate in other facilities.

  As a thing which heats other facilities using the heat of the cooling water heated at the time of cooling of a grate, there exists a thing of patent document 1, for example. In Patent Document 1, the heat of the cooling water heated at the time of cooling the grate is used as an economizer to heat the feed water of the boiler via a heat exchanger, or air preheating to preheat the combustion air to the waste incinerator. Garbage incinerators used for containers and the like are disclosed.

Unexamined-Japanese-Patent No. 2015-200440

  The waste incinerator described in Patent Document 1 is not assumed to be incorporated into a waste treatment plant provided with an internal combustion engine and the like, and Patent Document 1 does not disclose an internal combustion engine.

  Some waste treatment plants that generate electricity from steam generated by burning wastes have an internal combustion engine installed side by side. In such a waste treatment plant, it is necessary to warm up the internal combustion engine in order to start the additional internal combustion engine. There is known a method of supplying circulating water heated by a heater to an internal combustion engine when the internal combustion engine is warmed up. However, when circulating water heated by the heater is supplied to the internal combustion engine, power for heating the heater has been required.

  The present invention has been made in view of such circumstances, and heat is exchanged between a grate provided in a waste treatment plant and an internal combustion engine to provide heat in the waste treatment plant. An object of the present invention is to provide a waste treatment plant capable of effectively utilizing thermal energy with reduced loss.

In order to solve the above-mentioned subject, the waste disposal plant of the present invention adopts the following means.
According to an aspect of the present invention, there is provided a waste treatment plant comprising: a boiler generating steam by burning waste on a grate provided in a combustion furnace; a steam turbine driven by steam generated by the boiler A first generator that generates electric power by the driving force of the steam turbine, an internal combustion engine that drives a second generator that is a generator different from the first generator, the grate, and the internal combustion engine And a heat medium flow passage in which the heat medium flows.

  In the above configuration, the grate and the internal combustion engine are connected, and the heat medium flow path through which the heat medium flows is provided inside. Thereby, heat can be transferred between the grate provided in the waste treatment plant and the internal combustion engine. Therefore, the heat loss in the waste treatment plant can be reduced and the thermal energy can be used effectively.

  If the temperature of the heat medium discharged from the grate is higher than that of the internal combustion engine, the heat medium discharged from the grate heats the internal combustion engine. That is, the heat medium heated by heat exchange with the grate is supplied to the internal combustion engine, and heats the internal combustion engine by heat exchange with the internal combustion engine. Thereby, for example, when the temperature of the internal combustion engine is low and warm-up is required, such as before the start of operation of the internal combustion engine, the heat of the grate can be used to warm up the internal combustion engine. Therefore, the internal combustion engine can be warmed up without providing a heater or the like for warming up the internal combustion engine. Therefore, compared with the case where a heater etc. are provided, while simplifying the installation of a waste processing plant and reducing installation cost, the power consumption by a heater etc. can be reduced and running cost can be reduced.

  Further, in the above configuration, the heat medium flow path connects the grate and the internal combustion engine. Thereby, heat can be directly transferred between the grate and the internal combustion engine. Therefore, the heat loss can be reduced as compared to the case where heat is exchanged between the grate and the internal combustion engine through the heat exchanger or the like.

  In the waste treatment plant according to one aspect of the present invention, a temperature measurement unit that measures the temperature of the heat medium discharged from the internal combustion engine, and a flow rate that adjusts the flow rate of the heat medium supplied to the internal combustion engine Adjustment means may be provided, and the flow rate adjustment means may supply the internal combustion engine based on the temperature measured by the temperature measurement means.

In the above configuration, the amount of heat medium supplied to the internal combustion engine is adjusted based on the temperature of the heat medium discharged from the internal combustion engine. The heating state of the internal combustion engine can be determined by measuring the temperature of the heat medium discharged from the internal combustion engine. Therefore, the amount of the heat medium can be adjusted based on the heating state of the internal combustion engine, so that the internal combustion engine can be accurately heated.
Note that the meaning of “adjusting the flow rate of the heat medium supplied to the internal combustion engine” in the above configuration also includes not supplying the heat medium to the internal combustion engine. The state in which the heat medium is not supplied to the internal combustion engine means, for example, a state in which the operation of the internal combustion engine is started and it is not necessary to warm up the internal combustion engine.

  The waste treatment plant according to one aspect of the present invention further includes a feed water heating unit that heats the feed water supplied to the boiler, and the heat medium flow path branches from between the grate and the internal combustion engine. The heat transfer medium includes a branch heat medium flow passage connected to the water supply heating unit, the water supply heating unit exchanges heat between the heat medium and the water supply, and the heat medium flow passage is supplied to the internal combustion engine. The branch flow rate adjustment means may be provided to adjust the flow rate of the heat medium and the flow rate of the heat medium supplied to the feed water heating unit.

In the above configuration, the grate and the feed water heating unit are connected by the heat medium flow channel. Thereby, the heat of the grate can be used to heat the feed water.
Further, in the above configuration, the branch flow rate adjusting unit adjusts the flow rate of the heat medium supplied to the internal combustion engine and the flow rate of the heat medium supplied to the feed water heating unit. Accordingly, it is possible to prevent the situation where the heat medium is excessively supplied to the internal combustion engine and the feed water heating unit, or the situation where the heat medium is supplied when the heat medium is unnecessary. Therefore, it becomes possible to supply an appropriate amount of heat transfer medium to the place where the heat transfer medium is required in the waste treatment plant, and more preferably, the heat loss is reduced in the entire waste treatment plant to effectively utilize the heat energy. It can be used to
The meaning of "adjusting the flow rate of the heat medium supplied to the internal combustion engine and the flow rate of the heat medium supplied to the water supply heating unit" in the above configuration includes an internal combustion engine or a water supply heating unit. A state in which the heat medium is not supplied is also included. The state in which the heat medium is not supplied to the internal combustion engine means, for example, a state in which the operation of the internal combustion engine is started and it is not necessary to warm up the internal combustion engine.

  Further, the waste treatment plant according to one aspect of the present invention includes a temperature measuring unit that measures the temperature of the heat medium discharged from the internal combustion engine, and the branch is performed based on the temperature measured by the temperature measuring unit. The flow rate adjustment unit may adjust the flow rate of the heat medium supplied to the internal combustion engine and the flow rate of the heat medium supplied to the feed water heating unit.

  In the above configuration, the amount of the heat medium can be adjusted based on the heating state of the internal combustion engine, so that the internal combustion engine can be accurately heated, and the heat medium unnecessary for heating the internal combustion engine can be supplied. It can be used in the heating unit. Therefore, the heat loss in the whole waste treatment plant can be reduced, and thermal energy can be used effectively.

  Further, the waste treatment plant according to one aspect of the present invention includes a heat exchange unit that exchanges heat between the combustion exhaust gas discharged from the internal combustion engine and the heat medium supplied to the feed water heating unit. Good.

  In the above configuration, the heat exchange unit is provided to exchange heat between the combustion exhaust gas discharged from the internal combustion engine and the heat medium supplied to the feed water heating unit. Thus, after the start of operation of the internal combustion engine, the heat of the combustion exhaust gas can be used to heat the feedwater supplied to the boiler via the heat exchange unit and the feedwater heating unit. Therefore, the heat loss in the whole waste treatment plant can be reduced, and thermal energy can be used effectively.

  ADVANTAGE OF THE INVENTION According to this invention, the heat loss in the whole waste treatment plant can be reduced, and thermal energy can be used effectively.

It is a schematic block diagram which shows the waste treatment plant which concerns on 1st Embodiment of this invention, Comprising: The state which is supplying the heat medium to the internal combustion engine is shown. It is a schematic block diagram which shows the waste treatment plant which concerns on 1st Embodiment of this invention, Comprising: The state which is supplying the heat medium to the feed water heater is shown. It is a schematic block diagram which shows the waste treatment plant which concerns on 2nd Embodiment of this invention. It is a schematic block diagram which shows the waste treatment plant which concerns on 3rd Embodiment of this invention.

Hereinafter, an embodiment of a waste treatment plant according to the present invention will be described with reference to the drawings.
First Embodiment
Hereinafter, a first embodiment of the present invention will be described using FIGS. 1 and 2.
As shown in FIG. 1 and FIG. 2, the waste treatment plant 1 according to the present embodiment generates steam by combustion gas generated by burning waste on a grate 9 provided in a combustion furnace 2. , A steam turbine 4 driven by steam from the boiler 3, a methane fermentation tank 5 generating methane-containing biogas from waste, and a gas engine driven by the methane-containing biogas from the methane fermentation tank 5 It is equipped with six. In addition, the waste treatment plant 1 generates electric power by the first generator 7 and the second generator 8. The rotation shaft of the first generator 7 is connected to the rotation shaft of the steam turbine 4, and the first generator 7 generates electric power by the rotation force of the steam turbine 4. Further, the rotating shaft of the second generator 8 is connected to the rotating shaft of the gas engine 6, and the second generator 8 generates electric power by the driving force of the gas engine 6.

  The boiler 3 has a combustion furnace 2 which burns waste to generate combustion gas, a flue 11 which guides the combustion gas generated in the combustion furnace 2, and a feed water flowing inside and is installed in the flue 11 And a plurality of heat transfer tubes.

  The combustion furnace 2 transfers the waste introduced from the waste supply passage 12 onto the grate 9 by the grate 9. In the combustion furnace 2, combustion air is introduced from the furnace bottom, and after drying and thermal decomposition of wastes in the primary combustion chamber formed on the grate 9, combustion is performed on the downstream side of the grate 9 Conduct and produce combustion gas. The combustion air flows in the combustion air introducing pipe 13 communicating with the combustion furnace 2 and is introduced into the combustion furnace 2.

  The grate 9 has a grate main body 9a for transferring wastes and grate piping 9b for cooling the grate main body 9a. The grate piping 9b is provided inside or on the back side of the grate main body 9a. The grate piping 9b is provided along substantially the entire surface of the grate main body 9a, and cooling water (heat medium) flowing inside exchanges heat with the grate main body 9a. The cooling water flowing in the grate piping 9b flows into the grate piping 9b from the inlet and is discharged from the outlet.

  The combustion gas generated in the combustion furnace 2 flows in the flue 11. The combustion gas exchanges heat with the feed water flowing in a plurality of heat transfer pipes (not shown) installed in the flue 11. The combustion gas which has completed the heat exchange with the feed water flowing in the heat transfer pipe is discharged from the boiler 3 as a combustion exhaust gas. The combustion exhaust gas discharged from the boiler 3 flows in the combustion exhaust gas pipe 17, is subjected to necessary processing in the bag filter 18, and is exhausted from the chimney 20 to the atmosphere through the fan 19.

  The heat transfer tube extends into the flue 11 and is folded back a plurality of times near the wall of the flue 11. Water supply circulates inside the heat transfer tube. The upstream end of the heat transfer pipe communicates with the steam supply pipe 21, and the downstream end communicates with the water supply pipe 22. The heat exchange between the feed water flowing in the heat transfer pipe and the combustion gas flowing in the flue 11 generates steam.

  The generated steam flows in the steam supply pipe 21 and is introduced into the steam turbine 4. The steam introduced into the steam turbine 4 rotates the steam turbine 4. The rotating shaft of the first generator 7 is connected to the rotating shaft of the steam turbine 4, and when the steam turbine 4 rotates, the first generator 7 is driven to generate electric power. A part of the steam introduced into the steam turbine 4 is supplied to a second feed water heater 26 described later via the bleed steam pipe 23.

The steam that has rotated the steam turbine 4 condenses in the condenser 24 into water. The water generated by the condenser 24 flows in the water supply pipe 22 and is supplied as a water supply to a heat transfer pipe provided in the boiler 3. A first feedwater heater (feedwater heating unit) 25 and a second feedwater heater 26 are provided in the feedwater supply pipe 22 sequentially from the upstream side. The first feed water heater 25 is provided with a heat exchanger 25a, and the heat exchange between the coolant flowing through the heat exchanger 25a and the feed water supplied from the condenser 24 to the boiler 3 causes the feed water to be reduced. It is heated. In the second feed water heater 26, the feed water heated by the first feed water heater 25 is further heated by part of the steam extracted from the steam turbine 4. The water or steam after the feed water is heated by the second feed water heater 26 is returned to the condenser 24 through the discharge pipe 27.
The feed water is heated by both the first feed water heater 25 and the second feed water heater 26 because cooling water heated by the grate 6 with respect to the first feed water heater 25 is used, as shown in FIG. Only if it is supplied. As shown in FIG. 1, when the cooling water is not supplied to the first feed water heater 25, the feed water is heated only by the second feed water heater 26.

  The waste to be subjected to the methane fermentation treatment is supplied to the methane fermentation tank 5 via the methane fermentation tank waste supply passage 15. In the methane fermenter 5, the methane-containing biogas is produced from the waste subjected to the methane fermentation treatment. The generated methane-containing biogas is supplied to the gas engine 6 via the biogas supply pipe 28. Moreover, the sludge produced | generated when producing | generating methane containing biogas is discharged | emitted from the methane fermentation tank 5, distribute | circulates the inside of the sludge discharge pipe 29, and is collect | recovered by a sludge collection part (illustration omitted).

The gas engine 6 has an engine body 6a driven by methane-containing biogas and an engine pipe 6b for cooling the engine body 6a.
The engine main body 6a burns and drives the methane-containing biogas supplied from the biogas supply pipe 28 together with the air supplied from the air supply device (not shown) via the air supply pipe 38. In the engine body 6a, a piston (not shown) to be driven is converted into rotational motion by a crankshaft (not shown). The rotating shaft of the second generator 8 is connected to the rotating shaft of the engine body 6a, and the second generator 8 is driven by driving the engine body 6a to generate electric power.
The engine pipe 6b is provided inside the engine body 6a, and the cooling water flowing inside the engine pipe 6b exchanges heat with the engine body 6a. The cooling water flowing in the engine piping 6b flows into the engine piping 6b from the inlet and is discharged from the outlet.

  The combustion exhaust gas discharged from the gas engine 6 flows in the combustion exhaust gas pipe 30 for the engine, joins the combustion exhaust gas pipe 17, and is exhausted to the atmosphere from the chimney 20 through the fan 19.

Further, the waste treatment plant 1 according to the present embodiment includes a circulation flow passage (heat medium flow passage) 10 connecting the grate 9, the gas engine 6 and the first feed water heater 25. The circulation flow path 10 includes a first cooling water flow path 31 and a second cooling water flow path 32 which directly connect the grate 9 and the gas engine 6. Cooling water is circulated in the first cooling water channel 31 and the second cooling water channel 32.
The first cooling water flow path 31 connects the outlet of the grate piping 9 b provided in the grate 9 and the inlet of the engine piping 6 b. The second coolant passage 32 connects the outlet of the engine pipe 6b to the inlet of the grate pipe 9b.

  In addition, the circulation flow passage 10 branches from a first branch flow passage (branch heat transfer medium flow passage) 33 branched from an intermediate position of the first cooling water flow passage 31 and a second branched from a middle position of the second cooling water flow passage 32. And a branched flow passage (branched heat medium flow passage) 34. The first branch flow path 33 connects the middle position of the first cooling water flow path 31 and the inflow port of the heat exchanger 25 a provided in the first feed water heater 25. The second branch flow path 34 connects the discharge port of the heat exchanger 25 a and the halfway position of the second cooling water flow path 32. Cooling water is circulated in the first branch flow channel 33 and the second branch flow channel 34.

  Further, a first flow path switching valve (flow rate adjustment means, branch flow rate adjustment means) 35 is provided in the first cooling water flow path 31 at a position where the first branch flow path 33 branches. The first flow path switching valve 35 switches whether the cooling water sent from the grate pipe 9b is supplied to the engine pipe 6b or the heat exchanger 25a.

Further, a second flow path switching valve 36 is provided in the second cooling water flow path 32 at a position where the second branch flow path 34 branches. The second flow path switching valve 36 switches whether the cooling water sent from the engine pipe 6 b is supplied to the grate pipe 9 b or the heat exchanger 25 a. Further, the second flow path switching valve 36 switches whether the cooling water sent from the heat exchanger 25a is supplied to the grate piping 9b or the engine piping 6b.
Further, a thermometer (temperature measuring means) 37 is provided in the second cooling water flow passage 32 between the discharge port of the engine pipe 6 b and the second flow passage switching valve 36. The thermometer 37 measures the temperature of the cooling water discharged from the outlet of the engine pipe 6b.

  Next, the flow of the cooling water in the present embodiment will be described.

[Before starting gas engine operation]
During the operation of the boiler 3 and before the start of the operation of the gas engine 6, as shown in FIG. 1, the cooling water circulates between the grate 9 and the gas engine 6. The flow of the cooling water before the start of the operation of the gas engine 6 will be described in detail below.

  During operation of the boiler 3, the grate main body 9 a is heated by the influence of a flame or the like formed in the combustion furnace 2 of the boiler 3. At this time, the heat exchange between the cooling water flowing in the grate piping 9 b and the grate main body 9 a cools the grate main body 9 a and heats the cooling water. The heated cooling water flows into the first cooling water channel 31 from the outlet of the grate piping 9b. The temperature of the cooling water discharged from the outlet of the grate pipe 9 b is a temperature sufficient to warm up the gas engine 6. At this time, the first flow path switching valve 35 provided in the first cooling water flow path 31 is switched so as to lead the cooling water to the gas engine 6. Thereby, the cooling water which circulates the 1st cooling water channel 31 is led to engine piping 6b of gas engine 6, and flows in into engine piping 6b from an inflow mouth.

The cooling water flowing into the engine pipe 6b exchanges heat with the engine body 6a while flowing through the engine pipe 6b. At this time, since the gas engine 6 is in a state before the start of operation, the engine body 6a is in a state of lower temperature than the cooling water flowing in the engine piping 6b. Therefore, heat exchange between the engine body 6 a and the cooling water heats the engine body 6 a and cools the cooling water. The cooled cooling water flows into the second cooling water channel 32 from the outlet of the engine pipe 6b. At this time, the second flow path switching valve 36 provided in the second cooling water flow path 32 is switched so as to lead the cooling water to the grate 9. Thus, the cooling water flowing through the second cooling water flow path 32 is led to the grate piping 9 b of the grate 9 and flows into the grate piping 9 b from the inflow port.
Thus, before the start of the operation of the gas engine 6, cooling water circulates between the grate 9 and the gas engine 6 to cool the grate main body 9a and warm up the engine main body 6a. There is.

[After start of gas engine operation]
During the operation of the boiler 3 and after the start of the operation of the gas engine 6, as shown in FIG. 2, the cooling water circulates between the grate 9 and the first feed water heater 25. The flow of the cooling water after the start of the operation of the gas engine 6 will be described in detail below.

  During the operation of the boiler 3, the cooling water flows into the first cooling water flow path 31 from the outlet of the grate piping 9b in a heated state. At this time, the first flow path switching valve 35 provided in the first cooling water flow path 31 is switched so as to lead the cooling water to the first water supply heater 25 via the first branch flow path 33. Thereby, the cooling water which circulates the 1st cooling water channel 31 flows into the 1st branching channel 33 from the halfway position. Then, the cooling water flowing through the first branch flow path 33 is led to the heat exchanger 25 a of the first feed water heater 25 and flows into the heat exchanger 25 a from the inflow port.

The cooling water that has flowed into the heat exchanger 25a exchanges heat with the water supplied from the condenser 24 to the boiler 3 while flowing through the heat exchanger 25a. At this time, since the temperature of the feed water is lower than the temperature of the cooling water, the heat exchange between the feed water and the cooling water heats the feed water and cools the cooling water. The cooled cooling water flows into the second branch flow path 34 from the outlet of the heat exchanger 25a. At this time, the second flow path switching valve 36 provided in the second cooling water flow path 32 is switched so as to lead the cooling water to the grate 9. Thus, the cooling water flowing through the second branch flow channel 34 joins the second cooling water flow channel 32 from an intermediate position of the second cooling water flow channel 32 and is led to the grate 9. The cooling water led to the grate 9 flows into the grate piping 9b from the inlet.
As described above, after the start of the operation of the gas engine 6, the cooling water circulates between the grate 9 and the first feed water heater 25 to cool the grate main body 9 a and to supply the water supplied to the boiler 3. Is heating.

As described above, in the present embodiment, the first flow passage switching valve 35 and the second flow passage switching valve 36 in the state before the start of the operation of the gas engine 6 and the state after the start of the operation of the gas engine 6. The flow path of the cooling water is changed.
The change of the flow path of the cooling water confirms that the operation of the gas engine 6 has been started, and manually operates the first flow path switching valve 35 and the second flow path switching valve 36 to change the flow path. It is also good. In addition, a control device (not shown) is provided, and the control device determines whether the operation of the gas engine 6 has been started or not and determines that the operation of the gas engine 6 has been started. The flow path may be changed by operating the first flow path switching valve 35 and the second flow path switching valve 36.
When the control device determines whether or not the operation of the gas engine 6 is started, the temperature of the cooling water discharged from the engine piping 6b is measured by the thermometer 37 provided in the second cooling water flow path 32. You may judge based on. Specifically, when the temperature of the cooling water discharged from the engine piping 6b becomes equal to or higher than a predetermined temperature, it is determined that the cooling water is heated by the operation of the engine main body 6a, and the gas engine 6 is It may be determined that the driving of the vehicle has been started.

  The control device includes, for example, a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), a computer readable storage medium, and the like. Then, a series of processes for realizing various functions are stored in the form of a program, for example, in a storage medium or the like in the form of a program, and the CPU reads this program into a RAM or the like to execute information processing and arithmetic processing. Thus, various functions are realized. The program may be installed in advance in a ROM or other storage medium, may be provided as stored in a computer-readable storage medium, or may be distributed via wired or wireless communication means Etc. may be applied. The computer readable storage medium is a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory or the like.

According to the present embodiment, the following effects are achieved.
In the present embodiment, the grate 9 and the gas engine 6 are connected to each other, and the first cooling water passage 31 and the second cooling water passage 32 through which the cooling water flows are provided. Thereby, heat can be transferred between the grate 9 provided in the waste treatment plant 1 and the gas engine 6. Further, the grate 9 and the first feed water heater 25 are connected via the first branch flow path 33 and the second branch flow path 34. Thereby, heat can be transferred between the grate 9 provided in the waste treatment plant 1 and the first feed water heater 25. As mentioned above, the heat loss in the waste treatment plant 1 can be reduced, and thermal energy can be used effectively.

  Specifically, before the start of the operation of the gas engine 6, the cooling water heated by heat exchange with the grate main body 9 a is supplied to the gas engine 6 to heat the gas engine 6. Thereby, the heat of the grate 9 can be utilized to warm up the gas engine 6. Therefore, the gas engine 6 can be warmed up without providing a dedicated heater or the like for warming up the gas engine 6. Therefore, as compared with the case where a dedicated heater or the like is provided, the equipment of the waste treatment plant 1 can be simplified and the equipment cost can be reduced, and the power consumption by the heater or the like can be reduced to reduce the running cost.

  After the gas engine 6 starts operating, the cooling water heated by heat exchange with the grate main body 9a is supplied to the first feed water heater 25 to heat the feed water. Thus, the heat of the grate 9 can be used to heat the feed water before being supplied to the second feed water heater 26 (hereinafter, referred to as “preheating”). By heating the feed water before being supplied to the second feed water heater 26, the heat used when heating the feed water in the second feed water heater 26 can be reduced. That is, in the present embodiment, a part of the steam is extracted from the steam turbine 4 in the second feed water heater 26, and the feed water is heated using the steam. By preheating, the amount of steam extracted from the steam turbine 4 can be reduced. As a result, the amount of power generation of the first generator 7 driven by the steam turbine 4 is improved as much as the amount of extraction air is reduced. That is, the amount of power generation of the entire waste treatment plant 1 is improved. Therefore, the power generation efficiency of the entire waste treatment plant 1 can be improved as compared to the case where the heat generated by the gas engine 6 is not used for preheating feed water.

  Further, in the present embodiment, the cooling water from the grate 9 is supplied to the gas engine 6 before the gas engine 6 starts operation, and the gas engine 6 starts operation and the gas engine 6 generates heat. After the start of operation of a certain gas engine 6, the cooling water from the grate 9 is supplied to the first feed water heater 25. Thereby, in the situation where it is not necessary to warm up the gas engine 6 and it is not necessary to supply the cooling water to the gas engine 6, the thermal energy of the grate 9 is supplied without supplying the cooling water to the gas engine 6. It can be used to heat the Therefore, more suitably, the heat loss in the whole waste treatment plant can be reduced, and thermal energy can be used effectively.

Further, in the present embodiment, the first cooling water channel 31 and the second cooling water channel 32 directly connect the grate 9 and the gas engine 6. Thereby, heat can be directly transferred between the grate 9 and the gas engine 6. Therefore, the heat loss can be reduced as compared with the case where heat is exchanged between the grate 9 and the gas engine 6 via a heat exchanger or the like.
Similarly, the grate 9 and the first feed water heater 25 are directly connected. Thereby, heat can be directly transferred between the grate 9 and the first feed water heater 25. Therefore, the heat loss can be reduced as compared to the case where heat is exchanged between the grate 9 and the first feed water heater 25 through the heat exchanger or the like.

Second Embodiment
Hereinafter, a second embodiment of the present invention will be described with reference to FIG.
The present embodiment basically has the same structure as that of the first embodiment, and the first cooling water flow passage 31 and the second cooling water flow passage 32 have a first flow passage switching valve 35 and a second flow passage switching valve 36. It differs from the first embodiment in that a flow control valve is provided instead of being provided. Moreover, the point by which the on-off valve is provided in the 1st branch flow path 33 and the 2nd branch flow path 34 differs from 1st Embodiment. The same components as those of the first embodiment are denoted by the same reference numerals and the description thereof will be omitted.

A first flow control valve (flow control means, branch flow control means) 41 is provided in the first cooling water flow path 31 between the branch position P1 where the first branch flow path 33 branches and the inflow port of the engine pipe 6b. It is done. In addition, a second flow control valve (flow control means, branch flow control means) 42 between the branch position P2 at which the second branch flow path 34 branches to the second cooling water flow path 32 and the outlet of the engine pipe 6b. Is provided. In addition, a first on-off valve 43 is provided in the first branch flow path 33. Further, a second on-off valve 44 is provided in the second branch flow path 34. The first flow control valve 41 and the second flow control valve 42 adjust the opening degree to adjust the flow rate of the cooling water flowing through each flow path.
Moreover, the waste treatment plant 1 which concerns on this embodiment is provided with the control apparatus (illustration omitted) which controls each flow regulating valve and each on-off valve. The temperature of the cooling water measured by the thermometer 37 is sequentially transmitted from the thermometer 37 to the control device.

  Next, the flow of the cooling water in the present embodiment will be described.

[Before starting gas engine operation]
In the present embodiment, before the start of operation of the gas engine 6, as shown in FIG. 3, the cooling water from the grate 9 is distributed to both the gas engine 6 and the first feed water heater 25. That is, before the start of the operation of the gas engine 6, all of the first flow control valve 41, the second flow control valve 42, the first on-off valve 43 and the second on-off valve 44 are open. At this time, in the first cooling water flow path 31 and the second cooling water flow path 32, cooling water having a predetermined flow rate determined to be capable of suitably warming up the gas engine 6, which has been determined in advance by experiment, etc. There is. Further, in the first branch flow channel 33 and the second branch flow channel 34, the flow rate of the cooling water flowing in the first branch flow channel 33 and the second branch flow channel 34 is reduced from the total amount of circulating cooling water. Flow of cooling water is flowing. That is, surplus cooling water flows in the first branch flow path 33 and the second branch flow path 34.

Also, if the temperature of the cooling water measured by the thermometer 37 is lower than a predetermined value (about 90 degrees in this embodiment), it is determined that the gas engine 6 has not been sufficiently warmed up. The control device performs control to increase the opening degree of the first flow rate adjustment valve 41, and increases the flow rate of the cooling water supplied to the gas engine 6. In addition, while performing control which increases the opening degree of the 1st flow regulating valve 41, control which decreases the opening degree of the 2nd flow regulating valve 42 is performed, and the flow volume of the cooling water supplied to the gas engine 6 is increased. It is also good. When the flow rate of the cooling water supplied to the gas engine 6 increases, the thermal energy supplied to the gas engine 6 increases, and the temperature of the gas engine 6 rises. The above predetermined value is an example, and the threshold value for increasing the flow rate of the cooling water supplied to the gas engine 6 is not limited to 90 degrees.
Thus, cooling water is circulated between the grate 9 and the gas engine 6 and the first feed water heater 25 before the start of the operation of the gas engine 6. As a result, the grate main body 9a is cooled, the engine main body 6a is warmed up, and the feed water supplied to the boiler 3 is heated.

[After start of gas engine operation]
After the start of the operation of the gas engine 6, as in the first embodiment, the cooling water is circulated between the grate 9 and the first feed water heater 25 without being supplied to the gas engine 6. The flow of the cooling water after the start of the operation of the gas engine 6 is the same as that of the first embodiment, and thus the detailed description thereof is omitted.
After the gas engine 6 starts operating, the opening of the first flow control valve 41 is set to 0% (that is, fully closed), and the opening of the second flow control valve 42 is set to 100% (that is, fully open). Be done. Further, the second on-off valve 44 is opened, and the first on-off valve 43 is closed to prevent reverse flow.

The following effects are achieved in the present embodiment.
Further, the flow rate of the cooling water supplied to the gas engine 6 and the flow rate of the cooling water supplied to the first feed water heater 25 are adjusted by the first flow rate adjusting valve 41 and the second flow rate adjusting valve 42. Thereby, the situation where the cooling water is excessively supplied to the gas engine 6 and the first feed water heater 25 can be prevented. Therefore, it becomes possible to supply a suitable amount of cooling water to the required portion in the waste treatment plant 1, and more suitably, the heat loss in the entire waste treatment plant 1 is reduced to effectively utilize the thermal energy. can do.

  In the present embodiment, the flow rate of the cooling water supplied to the gas engine 6 is adjusted based on the temperature of the cooling water discharged from the gas engine 6. By measuring the temperature of the cooling water discharged from the gas engine 6, the warm-up state of the gas engine 6 can be determined. Therefore, the amount of cooling water can be adjusted based on the warm-up state of the gas engine 6, so that the gas engine 6 can be warmed up properly. In addition, cooling water that is not necessary for warming up the gas engine 6 can be used in the first feed water heater 25. From the above, more suitably, the heat loss in the whole waste treatment plant can be reduced to effectively utilize the thermal energy.

Third Embodiment
Hereinafter, a third embodiment of the present invention will be described with reference to FIG.
In this embodiment, there is basically the same structure as in the first embodiment, and the cooling water which exchanges heat between the combustion exhaust gas discharged from the gas engine 6 and the cooling water supplied to the first feed water heater 25. This embodiment differs from the first embodiment in that a heating unit (heat exchange unit) 51 is provided. The same components as those of the first embodiment are denoted by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 4, the waste treatment plant 1 according to the present embodiment performs a heat exchange between the combustion exhaust gas discharged from the gas engine 6 and the cooling water supplied to the first feed water heater 25. 51 and a combustion exhaust gas supply pipe 52 which branches from an intermediate position of the engine combustion exhaust gas pipe 30 and guides the combustion exhaust gas of the gas engine 6 to the cooling water heating unit 51, and the gas engine 6 discharged from the cooling water heating unit 51 And a flue gas exhaust pipe 53 for introducing the flue gas of the present invention into the flue gas pipe 17. A third flow passage switching valve 54 is provided at a position where the combustion exhaust gas supply pipe 52 branches from the engine combustion exhaust gas pipe 30. The third flow path switching valve 54 switches whether the combustion exhaust gas from the gas engine 6 flows into the combustion exhaust gas pipe 17 or into the combustion exhaust gas supply pipe 52.
Cooling water flowing through the inside of the first branch flow path 33 is supplied to the cooling water heating unit 51.

The following effects are achieved in the present embodiment.
In the above configuration, the cooling water heating unit 51 that exchanges heat between the combustion exhaust gas discharged from the gas engine 6 and the cooling water supplied to the first feed water heater 25 is provided. Since the combustion exhaust gas discharged from the gas engine 6 has a high temperature of 400 degrees to 500 degrees, the cooling water supplied to the first feed water heater 25 by the heat of the combustion exhaust gas after the start of the operation of the gas engine 6 Can be heated. By heating the cooling water supplied to the first feed water heater 25, the feed water can be further heated by the first feed water heater 25. Therefore, the thermal energy of the combustion exhaust gas of the gas engine 6 can be used to heat the feed water supplied to the boiler 3 via the cooling water heating unit 51 and the first feed water heater 25. Therefore, the heat loss in the whole waste treatment plant 1 can be reduced further, and thermal energy can be used effectively.

  The present invention is not limited to the invention according to the above-described embodiments, and appropriate modifications can be made without departing from the scope of the invention.

  For example, in each of the above embodiments, an example of applying the gas engine 6 driven by the methane-containing biogas from the methane fermentation tank 5 has been described for the internal combustion engine that supplies the cooling water heated by the grate 9. The invention is not limited to this. For example, cooling water heated by the grate 9 may be supplied to a backup engine that supplies electricity to the waste treatment plant 1 in an emergency. The backup engine is not in operation and in a standby state when the waste treatment plant is operating normally. On the other hand, when an error occurs in the waste treatment plant, the operation must be started immediately, and therefore, even in the standby state, the warm-up state must always be maintained. Therefore, the energy required for warm-up is large, and there is a problem that the cost increases when warm-up is performed by the heat of a heater or the like. It can be reduced.

  Moreover, although the said each embodiment demonstrated the example in which the single gas engine 6 was provided, two or more gas engines may be provided. In a waste treatment plant provided with a plurality of gas engines, one gas engine may be stopped for maintenance or the like, while power generation or the like may be maintained by another gas engine. By sequentially switching the gas engines to be operated in this manner, the number of times to start the operation of the gas engines also increases. Therefore, the energy required for warm-up is large, and there is a problem that the cost increases when warm-up is performed by the heat of a heater or the like. It can be reduced.

  Moreover, although the said each embodiment demonstrated the example which applies a gas engine, the kind of internal combustion engine is not limited to a gas engine. It may be an internal combustion engine that requires warm air, for example, a diesel engine.

  In the third embodiment, the third flow path switching valve 54 is provided at a position where the combustion exhaust gas supply pipe 52 branches from the engine exhaust gas pipe 30, and the combustion exhaust gas from the gas engine 6 is supplied to the combustion exhaust gas pipe 17. Although the configuration has been described that can switch whether to flow into the combustion exhaust gas supply pipe 52 or the pipe that joins the combustion exhaust gas supply pipe 52 from the third flow path switching valve 54 and the third flow path switching valve 54 Alternatively, the combustion exhaust gas may be always led to the cooling water heating unit 51. With such a configuration, the configuration of the waste treatment plant 1 is simplified by omitting the piping joining the combustion exhaust gas supply pipe 52 from the third flow passage switching valve 54 and the third flow passage switching valve 54. can do.

  Moreover, each said embodiment can be combined, respectively. For example, the first embodiment or the third embodiment may be combined with the second embodiment.

1 waste treatment plant 2 combustion furnace 3 boiler 4 steam turbine 5 methane fermenter 6 gas engine (internal combustion engine)
7 1st generator 8 2nd generator 9 grate 10 circulation channel (heat medium channel)
11 flue 12 waste supply passage 13 combustion air introduction pipe 15 methane fermentation tank waste supply passage 17 combustion exhaust gas pipe 21 steam supply pipe 22 water supply supply pipe 25 first water supply heater (water supply heating unit)
26 second feed water heater 28 biogas supply pipe 30 combustion exhaust gas pipe 31 for engine first cooling water flow path 32 second cooling water flow path 33 first branch flow path (branch heat transfer medium flow path)
34 2nd branch channel (branch heat medium channel)
35 1st flow path switching valve (flow control means, branch flow control means)
37 Thermometer (temperature measurement means)
41 1st flow control valve (flow control means, branch flow control means)
42 2nd flow control valve (flow control means, branch flow control means)
51 Cooling water heating unit (heat exchange unit)
52 Combustion exhaust gas supply pipe 53 Combustion exhaust gas discharge pipe

Claims (5)

A boiler that generates steam by burning waste on a grate provided in a combustion furnace;
A steam turbine driven by steam generated by the boiler;
A first generator that generates electric power by the driving force of the steam turbine;
An internal combustion engine for driving a second generator which is a generator different from the first generator;
A waste treatment plant comprising: a heat transfer medium flow path which connects the grate and the internal combustion engine and through which a heat transfer medium flows. Temperature measuring means for measuring the temperature of the heat medium discharged from the internal combustion engine;
Flow rate adjusting means for adjusting the flow rate of the heat medium supplied to the internal combustion engine;
The waste treatment plant according to claim 1, wherein the amount of the heat medium supplied to the internal combustion engine is adjusted by the flow rate adjusting means based on the temperature measured by the temperature measuring means. A feed water heating unit for heating feed water supplied to the boiler;
The heat medium flow path has a branch heat medium flow path branched from between the grate and the internal combustion engine and connected to the feed water heating unit,
The water supply heating unit exchanges heat between the heat medium and the water supply,
The branch flow rate adjusting means for adjusting the flow rate of the heat medium supplied to the internal combustion engine and the flow rate of the heat medium supplied to the feed water heating unit are provided in the heat medium flow path. Waste treatment plant described. Temperature measurement means for measuring the temperature of the heat medium discharged from the internal combustion engine;
Based on the temperature measured by the temperature measuring means, the branch flow rate adjusting means adjusts the flow rate of the heat medium supplied to the internal combustion engine and the flow rate of the heat medium supplied to the feed water heating unit The waste treatment plant according to claim 3. The waste disposal plant according to claim 3 or 4 provided with a heat exchange part which carries out heat exchange between the combustion exhaust gas discharged from said internal-combustion engine, and said heat carrier supplied to said feed water heating part.

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