JPH07332637A - Garbage incineration power generation system - Google Patents

Abstract

(57) [Summary] [Structure] In a waste incineration power generation system consisting of a waste pit 1 for collecting and storing waste, an incinerator 2, a boiler 3, a power generation facility, etc., heat for guiding exhaust heat generated in each part to the waste pit 1. The exchanging means and the heat exchanging means for taking out the heat collected in the waste pit 1 are provided, and the waste pit 1 is used as a heat storage tank. [Effect] Since the amount of heat generated by waste can be controlled before combustion, it is possible to perform stable combustion of waste whose heat generation changes.
Since the waste pit can be used as a heat storage tank, waste heat that fluctuates greatly can be used as a stable heat source for heat supply to the outside only by controlling the operation of the system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waste incineration power generation system, and more particularly to a waste incineration power generation system that can effectively use exhaust heat and surplus heat generated in each process of the system.

[0002]

2. Description of the Related Art A refuse incineration system can effectively use the heat of incineration. Therefore, a boiler is used to generate steam, a steam turbine is driven to generate electricity, and the energy of the refuse is recovered as electricity. It is generally done. However, when refuse is incinerated as fuel, components such as chlorine and sulfur contained in the refuse act to promote corrosion of the heat transfer tube. Since the higher the temperature is, the faster the corrosion progresses, the boiler cannot be operated at a temperature of 500 ° C. to 600 ° C. which is normally used, and the boiler is operated to generate steam of about 300 ° C. For this reason, the temperature of the steam entering the turbine becomes lower than that in the case of normal power generation, so that the power generation efficiency is low. In order to solve this problem and perform high-efficiency waste power generation, Japanese Patent Laid-Open No. 52-155882 discloses that exhaust gas of a gas turbine power generation system provided with a steam of about 300 ° C. obtained by normal waste incineration separately from a waste incinerator. There is disclosed a system for superheating to high temperature steam by utilizing. In this system, in the waste incinerator, steam is generated in a temperature range where there is little corrosion, and this steam is superheated by the gas turbine combustion exhaust gas that uses city gas with a low content of corrosion-promoting components as fuel to raise the steam temperature. The power generation efficiency can be improved while suppressing the corrosion due to the waste incineration exhaust gas. However, since these conventional refuse incineration systems are systems that place importance on power generation, effective use of exhaust heat when power demand is small and a large amount of power generation is not required is not considered so much. An example of utilizing exhaust heat of such a system is a waste incineration power generation system described in Japanese Patent Laid-Open No. 52-106045, which guides the gas turbine exhaust gas after exiting the superheater to the residual heat portion of the waste of the incinerator, It is only used for drying waste during the internal combustion process.

Further, the refuse incineration power generation system is usually continuously operated day and night, and a large amount of surplus heat is generated during the nighttime when the power demand is low. The system that uses this waste incineration waste heat for district heat supply is air conditioning and sanitary engineering, 66th
Vol. 6, No. 6. In this system, incineration waste heat is sent to the district cooling and heating energy center as hot water at a level of 45 ° C to 50 ° C, and is heated by a heat pump to be used for hot water supply. For this reason, a heat storage tank is provided in the energy center plant in order to stably supply the heat supplied from the waste incineration heat source from the cleaning plant. The heat storage equipment usually requires many places for installation and the construction cost is expensive, but it is an essential equipment for heat supply.

[0004]

As shown in the above-mentioned conventional example, the waste incineration power generation system does not take much measures for effective utilization of waste heat other than power generation. Also,
In order to use the exhaust heat externally for supplying district heat, it is necessary to provide an expensive heat storage facility in the energy center. Therefore, the present invention proposes a system in which waste heat or surplus heat in a refuse incineration power generation system is temporarily stored in its own system and is effectively used in consideration of system operation.

[0005]

According to the present invention, in order to achieve the above object, heat exchange means for recovering exhaust heat and surplus heat generated in each part of a refuse incineration power generation system and waste for collecting recovered heat are temporarily provided. There is provided heat exchange means for leading to the waste pit for storage, and further provided is heat exchange means for taking out the heat accumulated in the waste pit by the means. By these means, the waste pit, which was conventionally used as a temporary storage place for waste, can be used like a heat storage tank and operated to effectively use the waste heat and surplus heat of the waste incineration power generation system that fluctuates a lot. You can do it.

[0006]

By the above means, exhaust heat and surplus heat generated in each part of the system can be collected in the dust pit, and the heat acts to raise the temperature in the dust pit. Further, by operating the heat exchanging means for taking out this heat, the heat stored in the dust in the pit is taken away to lower the temperature. In this way, since the waste in the pit can exchange heat, the waste acts as a heat storage material, and since the waste pit is made with a certain capacity, it becomes possible to act as a heat storage tank.

Further, placing a heat exchanger in the waste pit and using exhaust heat collected from each part to raise the temperature of the waste in the pit promotes evaporation of water contained in the waste. As a result, the dust in the pit is dried, and the amount of heat generated by the dust is increased. However, when using a direct contact heat exchange means that directly guides excess steam to the waste pit without using a heat exchanger, the steam inside the pit should be moistened with this steam to reduce the heat value of the waste. Act on. By controlling these effects and using each other, they act to adjust the heat generation amount of the dust.

[0008]

EXAMPLES The present invention will be described below with reference to examples. Figure 1
Fig. 1 shows a refuse incineration power generation system configuration showing an embodiment of the present invention. The main components of this system are a waste pit 1, an incinerator 2, a boiler 3, a waste gas treatment part 4, a chimney 5, and a waste incineration facility part, and a steam turbine 7 for generating electricity with steam generated in the boiler, and a generator 8. It consists of the power generation equipment part. Next, the waste incineration process and heat utilization method in this system will be described.

In the waste incineration process, the waste collected by the waste collection vehicle or the like is collected from the waste carry-in port 12 to the waste pit 1 and temporarily stored until it is burned in the incinerator 2. The waste stored here is sequentially put into the incinerator 2 and incinerated by the waste crane 10 and the bucket 11. In this embodiment, a stalker-type incinerator is used, and the incineration ash 21 generated by burning the waste is collected in the lower part of the incinerator. The combustion gas 28 that has left the incinerator is guided to the boiler 3 in which heat transfer tubes are arranged, and generates steam. The generated steam is guided to the steam turbine 7 via the steam drum 6, and electricity is generated by the generator 8 connected to the steam turbine 7. In the conventional refuse incineration power generation system, all the steam that has exited the steam turbine is returned to the boiler via the condenser 9 and reused. It is supplied to the pit 1 and heat-exchanged directly with waste. On the other hand, the combustion gas 28 that has passed through the boiler 3 becomes combustion exhaust gas 29, and is discharged from the chimney 5 through the exhaust gas processing unit 4. The air for combusting the dust is sent to the combustion air supply port 19 provided in the combustion furnace 2 by the blower 17, but in the present embodiment, as is conventionally done, the combustion air preheater 18 produces sensible heat of the combustion exhaust gas. A part is recovered. However, in the present invention, the heat exchanger 13 is arranged further downstream, and the heat exchange means connected to the recovery heat exchanger 15 provided in the dust pit by the heat medium transport pipe 30 is provided. Furthermore, the heat exchanger 14 is also connected to the heat medium transport pipe to recover the heat of the incineration ash.
The heat recovered from each part in the waste pit by these configurations is accumulated in the waste in the pit, and this heat is transferred to the heat exchanger 16
It is used to supply heat outside the waste treatment system.

Next, the above system is operated to 200 tons per day.
The method of using heat will be described more specifically by taking the case of application to n waste treatment facilities as an example. In this case, a waste pit having a volume of about 400 m ³ is installed to temporarily store the incineration waste, and the amount of waste for about two days can be temporarily stored. The amount of heat generated by the waste collected in the pit varies depending on the type and ratio of the mixed waste, but it is generally 1
000 to 2000 kcal / kg, with an average calorific value of 15
If it is set to 00 kcal / kg, about 1250000 kcal / h of energy can be obtained by waste incineration. When burning these, 50
Combustion gas of 0 to 600 ℃ was obtained, of which 6000
00 kcal / h is used for steam generation in the boiler, and the rest is discharged as sensible heat of combustion exhaust gas. The boiler outlet temperature of the combustion exhaust gas is about 300 ° C., and this is used as a temperature lowering means to the exhaust gas treatment section for combustion air residual heat.
Bring to 200 ° C. Furthermore, from the exhaust gas of 150 ° C level that has been discharged from these exhaust gas treatment units, which has not been used before and was discarded from the chimney, heat is recovered as hot water of about 80 ° C using a water-gas heat exchanger to remove dust in the pit. Used for heating. Furthermore, in order to raise the temperature of this heat of recovery, the sensible heat of the incineration ash discharged at a temperature of 200 to 300 ° C. can be used. The amount of heat possessed by these is approximately 80,000 kcal / h, and hot water of approximately 180 ° C. can be obtained from this. This is mixed with 80 ° C. water that has been heat-recovered from the combustion exhaust gas, and hot water of 120 ° C. or higher is usually prepared to heat the dust pit. By heating the dust at this temperature, the temperature in the pit will rise from 80 ℃ to 9 ℃.
It reaches 0 ° C. The amount of heat stored at this time is 16 Gcal when the pit is full of dust. When this heat storage heat amount is used as heat supply to the outside using the heat exchanger 16, it is 80 ° C to 40 ° C.
If the temperature drop is allowed and the temperature difference between them is used for heat supply, about 8 Gcal of the heat accumulated in the waste can be used.

Further, by keeping the dust pit at 40 ° C. to 80 ° C. as described above, the water content in the dust can be evaporated, and therefore the amount of heat recovered from the exhaust heat source is adjusted and heated to cause the pit. It is possible to control the degree of drying of the waste inside. That is, by promoting drying, it is possible to increase the amount of heat generated during refuse incineration, if necessary. Further, when a large amount of a component having a large calorific value such as plastic is mixed, it is necessary to reduce the calorific value of the dust in order to prevent damage or the like due to the high temperature of the incinerator.
In order to deal with this, in the present embodiment, a part of the exhaust steam that has exited the steam turbine is branched and guided to the waste pit, and the steam and the waste are directly contacted and heat-exchanged to condense the steam so that the water content in the waste is reduced. The heating value is reduced by adding In addition, in this way, by adding steam to the waste before the incineration of the waste, the chlorine component in the waste reacts with the steam, and it becomes possible to remove chlorine, which is the corrosion promoting component of the heat transfer tube, as hydrogen chloride. Produce a positive effect.

In a waste incineration power generation system that operates fully for 24 hours, in order to more effectively operate the heat storage utilization of the waste pit according to the present invention, the excess waste heat is concentrated in the waste pit at night when power demand and heat demand are low. Heat treatment and dechlorination of waste, and during the daytime when power demand is high, efficient combustion of waste with preheated and stabilized calorific value in the pit increases power generation and stabilizes at the same time. The heat can be supplied as described above, the exhaust heat at night can be effectively used as compared with the conventional case, and it can contribute to the leveling of the electric power load. Especially when power is not generated at night, the effect of the present invention can be further enhanced by directly guiding the steam from the steam drum 6 to the dust pit 1 without passing through the steam turbine 7.

FIG. 2 shows an example in which the present invention is applied to a super refuse power generation system that superheats steam generated in a refuse incineration boiler by exhaust heat from a gas turbine.

The means for recovering heat to the dust pit in this embodiment has the same structure as that of the embodiment shown in FIG. 1, but in this embodiment, the gas turbine exhaust gas having a high temperature which has passed through the superheater 25 for steam is used. The system was introduced to the latter stage of the exhaust gas treatment unit 4 for waste combustion, and the heat was recovered in the exhaust gas sensible heat recovery heat exchanger 13. In this configuration, the heat exchanger 13 for recovering exhaust gas sensible heat is used.
Then, because it exchanges heat with the exhaust gas at about 300 ° C level,
The heat recovered is hot water of approximately 180 ° C level. In the drawing of this embodiment, a stalker type incinerator is used, so that heat recovery from incineration ash and heat recovery from combustion exhaust gas are performed simultaneously. However, when the present invention is carried out in a super-waste power generation system, sufficient recovery heat can be obtained to use the waste pit without using waste heat of incineration ash.
Therefore, the heat utilization method shown in the present embodiment is suitable for heat recovery utilization when high-temperature incineration ash is not generated. That is, since the incineration ash is collected by the cyclone, it is suitable for the heat recovery use of the super refuse incineration power generation system using the fluidized bed combustion furnace in which the generation of high temperature incineration ash from the furnace is small.

FIG. 3 shows an embodiment for more effectively utilizing the dust pit according to the present invention. This is a diagram showing a case where the equipment configuration of the plant of the refuse incineration system is viewed from above.

The dust pit 1 is used by dividing it laterally as shown in the drawing, and a heat exchange means is provided for each divided region. In the figure, the case where it is divided into four and used is shown. It is basically the same in this embodiment as in the above-described embodiment that exhaust heat and surplus heat generated in each part of the system are recovered and used in the dust pit. Therefore, a method of using the divided dust pits unique to this embodiment will be described below.

The respective garbage pits into which the area is divided are used by setting an application for each certain time zone. That is, when the dust pit is divided into four as in this embodiment, for example, each dust pit is divided into a heat storage step, a heat radiation step, a charging step and a collecting step depending on the use process. The assignment of each process at a certain time is shown in alphabetical letters corresponding to the figure. At this time, in the waste pit a in the heat storage step, only the recovery heat exchanger 15 operates by operating the valve of the heat exchange means, and the heat recovered by the exhaust gas sensible heat recovery heat exchanger 13 is collected in the waste pit a, The temperature of the waste pit is raised and the collected heat is stored. In the waste pit b, it is a process of radiating the recovered heat that has been stored, and the heat exchanger 16 operates to supply the recovered heat to heat demand areas such as district heating and cooling districts. Garbage pit c
Then, in the pit where the heat storage and heat dissipation processes have been completed, the waste remaining in the pit is in the waiting stage for incineration, and the process is to put the waste in the incinerator. The waste pit d is in the waste collecting step because the waste in the pit is incinerated and emptied in the previous step to newly collect and store the waste. As described above, in the steps c and d, the operation of the heat exchange means provided in the pit is stopped. However, although the operation monitoring and control of each process becomes complicated, by providing a means for monitoring the amount of dust in the pit, each heat exchange means is partially operated according to the amount of dust remaining in the pit. be able to. For example, in this case, in the waste pit d in the collection process, the waste collected from the stage of the waste collection process before the heat storage process is partially stored in the heat storage process by partially operating the recovery heat exchanger 15 at the same time as the waste collection. The pits can be used, and the dust pit can be used more efficiently than when each process is operated independently. In each of these steps, in the next stage, a to b, b to c, c
In this way, d is moved to d, d is moved to a, and so on, and the heat is always recovered and used in one of the waste pits where exhaust heat is divided. However, even in this case, the temperature is controlled so that the heat generation amount of the waste is stabilized at the same time as the heat recovery in the heated waste pit.

FIG. 4 shows an embodiment of the structure of a dust pit suitable for the present invention. A recovery heat exchanger 15 and a heat exchanger 16 are arranged as heat exchange means in the pit. These are fin-tube type heat exchangers including heat transfer tubes 32 and heat transfer fins 33, They are placed facing each other near the vertical wall as shown in the figure. However, it is desirable to provide a clearance between the wall surface and the heat transfer tube so that dust can move sufficiently. In this embodiment, the clearance between the wall surface and the heat transfer tube is 3
0 cm is provided. A screw feeder 31 having a structure in which a screw-shaped plate is rotated is provided between these heat exchangers in order to stir the dust in the pit. This moves the waste heated in the recovery heat exchanger one by one,
This is for uniformly heating the inside of the pit. Conventionally, heat transfer to waste is dominated by conduction heat transfer due to contact with the heat transfer tube, and it is difficult to use waste as a heat storage body because heat is difficult to transfer simply by disposing the heat transfer tube. However, as in the present embodiment, when the heat exchange means in the dust pit is a heat exchange means provided with a dust stirring mechanism, the dust can be treated like a fluid, so that the convection of the dust can be simulated. It causes heat transfer and can be used to accelerate heat transfer. For this reason, in the present embodiment, the screw feeder 31 is arranged obliquely to the heat transfer surface of the heat exchanger as shown in the drawing so that the dust in the lower part of the pit is stirred horizontally and simultaneously moves upward. I have to. With this stirring structure, the dust in the pit is also stirred in the vertical direction, so that the dust thrown into the pit above afterward can be sufficiently used for heat transfer. The same effect can be obtained even when a plurality of screw feeders are arranged vertically. With the above structure, the waste inside the pit can efficiently transfer heat while circulating between the heat recovery heat exchanger and the heat recovery heat recovery heat exchanger, and the heat storage effect of the waste pit can be used efficiently.

Further, in order to utilize the surplus steam, a steam supply pipe 35 having a large number of nozzle holes 34 is arranged at the lower portion of the pit, and the surplus steam is ejected into the pit from there. With this structure, the steam flows upward while passing through the gap of the dust and directly contacts the dust during this time, so that the dust can be heated and humidified at the same time.

In this structure, when the dust is taken out from the pit for charging the combustion furnace, the bucket is inserted between the heat exchanger and the agitator to scoop out the dust. For this reason, it is desirable to arrange them so that their intervals are larger than the bucket.

[0021]

EFFECTS OF THE INVENTION According to the present invention, exhaust heat and surplus heat generated in various places of the refuse incineration power generation system can be collected in the waste pit, and one of the effects is only temporary storage of the waste collected in the waste pit. The waste pit can be used as a heat storage tank, and the heat generation amount of waste in the pit can be controlled by adjusting the amount of heat recovered in the pit and the temperature level of the recovered heat source. In this way, it is possible to stabilize the combustion characteristics of waste that fluctuates greatly and to effectively use the surplus heat and exhaust heat generated in the waste incineration power generation system.

[Brief description of drawings]

FIG. 1 is a system diagram of a heat recovery type refuse incineration power generation system.

FIG. 2 is a system diagram of a heat recovery type super refuse power generation system.

FIG. 3 is a system diagram of a pit division type refuse incineration power generation system.

FIG. 4 is an explanatory diagram of a dust pit structure.

[Explanation of symbols]

1 ... Garbage pit, 2 ... Incinerator, 3 ... Boiler, 4 ... Exhaust gas treatment section, 5 ... Chimney, 6 ... Steam drum, 7 ... Steam turbine, 8 ... Generator, 9 ... Condenser, 10 ... Garbage crane, 1
1 ... Bucket, 12 ... Garbage entrance, 13, 14, 16 ...
Heat exchanger, 15 ... Recovery heat exchanger, 17 ... Blower, 18 ...
Combustion air preheater, 19 ... Combustion air supply port.

Claims (11)

[Claims] 1. In a refuse incineration power generation system in which collected waste is burned in an incinerator and steam is generated by using the heat to generate electric power, the generated waste is generated in the waste pit for temporary storage. A heat exchange means for introducing exhaust heat or surplus heat and a heat exchange means for extracting heat given to the dust in the waste pit by the heat exchange means are provided, and the waste pit is used for waste storage and heat storage. Characteristic refuse incineration power generation system. 2. A waste incineration power generation system in which collected waste is burned in an incinerator and steam is generated by using the heat to generate electricity by a steam turbine. Excess steam is stored in a waste pit for temporarily storing the collected waste. Is installed in the waste pit during storage of the waste while heat exchange means for direct contact with waste and sensible heat of combustion exhaust gas and / or sensible heat of waste incineration ash are provided at the same time. Alternatively, the waste incineration power generation system is characterized in that the heat generation amount of the waste is controlled by humidifying. 3. The refuse incineration power generation system according to claim 1, which uses a heat exchange means for guiding either or both of the sensible heat of the combustion exhaust gas and the sensible heat of the refuse combustion ash to the refuse in the pit at the same time. 4. The refuse incineration power generation system according to claim 1, wherein the turbine waste heat of the gas turbine power generation system is used for superheating steam generated by utilizing heat generated by combustion in a waste incinerator. 5. The power generation system according to claim 1, wherein the heat exchange means for guiding the excess heat generated by incineration is used in the waste pit for temporarily storing the collected waste, and is mainly used for power generation during a time period when the power demand is low at midnight. The excess steam that is not used is introduced into the waste pit as excess heat, the heat is stored in the waste, and the heat exchange means for extracting the heat given to the waste in the pit is used to extract the heat stored in the daytime when there is heat demand. Waste incineration power generation system to use. 6. The excess heat is introduced into the waste pit by using a heat exchange means for introducing the excess heat generated by incineration into the waste pit for temporarily storing the collected waste, and the heat is used as the waste. A waste incineration power generation system that uses the waste pit as a shock absorber to stabilize the heat supply while storing heat, while at the same time taking out the stored heat by the heat exchange means for taking out the heat given to the waste in the pit. 7. The refuse incineration power generation system according to claim 1, wherein a plurality of divided waste pit areas are provided and the waste pits are sequentially switched for each use process. 8. The waste pit area divided into four is provided, and each waste pit is divided into a heat storage step, a heat radiating step, a step of putting dust into a combustion furnace, and a step of collecting dust, and each use step. Waste incineration power generation system that sequentially switches from heat storage to heat radiation, heat radiation to input, and input to collection process. 9. The method according to claim 1, wherein a means for guiding the excess steam so as to come into direct contact with the waste is provided in the waste pit for temporarily storing the collected waste, and the waste is contained in the waste simultaneously with heating of the waste in the waste pit. A waste incineration power generation system that performs dechlorination by reacting the generated chlorine with water vapor. 10. The waste incineration power generation system according to claim 1, which has a heat exchange means provided with a heat exchanger and a stirrer in the waste pit. 11. The refuse incineration power generation system according to claim 10, comprising a heat exchanger composed of a fin-tube heat exchanger, a screw feeder, and an agitator.