JP2000145408A - Binary waste power generation method and its system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve high efficiency of waste power generation system such as city wastes, and to provide a method for achieving high efficiency of the city waste power generation system in particular and its system. SOLUTION: A binary waste power generation method serially connects a steam Rankine cycle and a low boiling point medium steam Rankine cycle to generate power through two stages. Topping cycle portion TP comprises a steam boiler 2 that recovers heat from gas exhausted from a waste incinerator 1, a topping turbine 5a that is driven by the steam generated in the steam boiler 2, and a topping generator 6a that generates power with the topping turbine 5a. Bottoming cycle portion BP comprises a heat exchanger 12 that generates steam of low boiling point medium using the exhaust of the topping turbine 5a as a heat source, a bottoming turbine 5b that is driven by steam generated, a bottoming generator 6b that generates power with the bottoming turbine 5b, and a capacitor 14 that returns the exhaust from the turbine 5b to liquid. Benzene, pentane, ammonia, etc., can be used as the low boiling point medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the efficiency of a waste power generation system that generates power using incineration waste heat of general waste such as household waste (hereinafter referred to as municipal waste) and industrial waste. Regarding the improvement, more specifically, a two-fluid waste power generation method and a two-fluid waste power generation method in which a steam Rankine cycle and a low-boiling-point medium steam Rankine cycle are connected in series to perform two-stage power generation and clarify the high-efficiency power generation conditions of municipal solid waste. Related to the device.

[0002]

2. Description of the Related Art The amount of generated waste such as municipal waste and industrial waste is increasing year by year, and among them, the increase in municipal waste is remarkable. Motivation to utilize unused energy as electric power has increased, and power generation systems that burn these wastes and use the waste heat thereof have become widespread. In particular, focusing on municipal solid waste, the number of power generation plants and the amount of power generation have steadily increased nationwide.

[0003] Generally, it is known that the exhaust gas of a municipal solid waste incinerator contains a high-temperature corrosive gas such as hydrogen chloride (HCl). In order to avoid corrosion, the steam temperature is usually 300
It is kept below ℃. Due to this temperature limitation, the power generation efficiency of existing municipal solid waste power generation plants is typically 12-15
%, And it is extremely difficult to exceed 18% even at the highest conditions, and it was considered that fundamental technological development was necessary to improve the power generation efficiency.

FIG. 5 is a configuration diagram of a conventional typical municipal waste power generator. The municipal solid waste A is burned in the incinerator 1, the combustion exhaust gas is sent to the steam boiler 2, and the heat supplied from the boiler feed pump 3 is heat-exchanged to steam at about 300 ° C. Part of this steam is sent to the plant 4 and used for air preheating, exhaust gas reheating, hot water supply, etc., and is returned to the steam boiler 2 via the deaerator 11.
The other steam is sent to the ejector 7 and the steam turbine 5, and power is generated by the generator 6 linked to the steam turbine 5. A part of the steam is extracted from the steam turbine 5 and sent to the deaerator 11, and the other exhausted steam is sent to the deaerator 11 via the condenser 8, the condensate pump 9 and the ejector steam condenser 10. And circulates again to the steam boiler 2. Makeup water B is supplied to the deaerator 11 to keep the water in the power generation system constant.

[0005] This conventional power generator performs a Rankine cycle using steam as a working medium. To put it simply, this Rankine cycle is composed of four processes: adiabatic compression by the feed water pump 3, isothermal superheating by the steam boiler 2, adiabatic expansion by the steam turbine 5, and isostatic cooling by the condenser 8. The three processes of isothermal heating, adiabatic expansion and isostatic cooling are shown as a Maurier diagram in FIG. The Maurier diagram is represented with enthalpy H on the vertical axis and entropy S on the horizontal axis.

The reason why the power generation efficiency of the conventional device is low will be described with reference to FIG. P ₁ is the inlet steam pressure, T ₁ of the steam turbine 5 is the inlet steam temperature, P ₂ is the outlet steam pressure, that is, exhaust pressure. As a practical condition of municipal waste generation, P ₁ is 3.0 MPa, P ₂ is 15.7KPa,
T ₁ is 295 ° C. It is 1 from the intersection I of the 3.0 MPa isobar heating line (solid line) and the 295 ° C. isothermal change line (dotted line).
Adiabatic expansion by the steam turbine occurs perpendicular to the 5.7 kPa isobar cooling line. The magnitude of the thermal drop f between the IJs gives the work, that is, the magnitude of the generated power. Actually, the entropy S is partially increased due to the friction loss, and the hatched arrow I
Since it falls according to the K-line, the thermal head is smaller.

[0007] To increase the heat drop f it is sufficient to raise the point I is, for its may be made large to P ₁ or T _1. However, the conventional municipal solid waste power generator has a limit of 300 ° C. in the boiler temperature. Therefore, it is a limit to keep T ₁ at 295 ° C. in consideration of heat loss due to a pipeline.
Therefore, there is no way but to increase the inlet steam pressure P _1. However, when gradually increasing the steam turbine inlet steam pressure P ₁ remains temperature 295 ° C., 12 to 13% wetness of the steam in the exhaust point on the line pressure 15.7kPa is in tolerance to the turbine Therefore, the steam turbine inlet steam pressure P ₁ is limited to about 3.0 MPa. Thus, the development of a method for extracting the theoretical thermal head f as large as possible has been an issue.

[0008] In order to solve this problem, in connection with measures to prevent global warming, the development of high-temperature and high-pressure steam boilers and the development of materials for corrosion-resistant superheated tubes have been promoted. Also, a super refuse power generation system in which a gas turbine power generation device is incorporated in a municipal refuse power generation plant is being introduced.

However, in the former, the steam condition is 4.0MP.
a, A corrosion-resistant superheated tube at 400 ° C has emerged, but at the same time as the equipment becomes extremely expensive, material development has not been completed yet in the higher temperature and high pressure region, and it has been established as a technology for higher efficiency. Hard to say. In the latter case, the power generation efficiency of the power plant as a whole is certainly improved, but only because the high power generation efficiency of about 30% of the gas turbine power generator itself has increased the overall power generation efficiency. In other words, the power generation efficiency of the original municipal waste power generation system has not been improved. In other words, it has been extremely difficult to achieve the high efficiency by using a conventional steam boiler having a 300 ° C. limit and using a popular steam turbine.

On the other hand, after the second oil crisis of 1978,
In terms of energy saving and utilization of unused energy,
As a medium-low temperature exhaust heat recovery system, an exhaust heat recovery power generation system using an organic medium as a working medium has been put to practical use. However, most of the organic medium is Freon-based, such as Freon 11-polyol ester oil, Florinol 85,
Freon 11-water mixture and the like. However, CFCs are substances that cause ozone depletion, and few plants are currently in operation due to problems such as corrosion of constituent materials due to working fluids and system defects.

Further, recently, as disclosed in Japanese Patent Publication No. 6-54082, a medium / low temperature exhaust heat recovery system using a mixture of a high-boiling medium and a low-boiling medium as a working medium has been proposed. . This system is a cycle having a feature of reducing exergy loss by using a change in a boiling point or a dew point accompanying a change in the concentration of a mixture. However, compared to the single-component cycle, there is a problem in plant operation of maintaining and controlling the concentration of two components, and in addition, the elemental technology of countermeasures against low-temperature corrosion of heat transfer tubes in heat exchange with medium- and low-temperature waste combustion exhaust gas is established. The problem remains.

As described above, the one-fluid waste power generation system using water, a chlorofluorocarbon-based organic medium, or a mixture medium as the working medium has been put to practical use, but as described above, each has its own problems. Was. In addition, since these perform only one-stage power generation with one fluid, there is a limit in improving the power generation efficiency.

[0013]

Under these circumstances, in the field of geothermal power generation, 150 to 200 gushing from underground.
A binary cycle power generation system that generates high-pressure low-boiling medium steam by transmitting the heat energy of medium- and high-temperature hot water to a low-boiling medium and drives the turbine with the steam was devised and developed for practical use. Is being continued.

In this power generation method, since a large amount of mineral components are contained in hot water spouted from underground, it is impossible to generate steam turbine power using steam of the hot water itself. This is because internal components such as turbines may be contaminated or corroded by mineral components, and harmful effects of fine particles contained in hot water may be considered. Then, the heat energy of the hot water is exchanged with the low-boiling-point medium, and the same problem occurs in this heat exchange. In other words, there is still a difficult problem of heat transfer reduction and corrosion due to internal contamination generated on the hot water side surface of the heat exchanger.

[0015]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a two-fluid waste power generation method according to the present invention is directed to a topping cycle in a preceding stage in which a Rankine cycle is performed using steam as a working medium. Unit and a bottoming cycle unit that performs a Rankine cycle using low-boiling-point medium steam as the working medium are connected in series, and high-temperature, high-pressure steam is generated by the waste heat of the waste incinerator, and the topping cycle is operated with this steam. To generate topping power, and as a result, heat exchange with relatively low-temperature, low-pressure steam produces low-temperature, high-pressure low-boiling-point medium steam, and the bottoming cycle is operated with the low-boiling-point medium vapor to generate bottoming power. It is characterized by performing.

Further, the two-fluid waste power generation apparatus according to the present invention comprises a topping cycle section in a preceding stage for performing a Rankine cycle using steam as a working medium and a bottoming cycle section in a latter stage for performing a Rankine cycle using low boiling medium steam as a working medium. In series, the topping cycle section is a steam boiler that recovers heat from the waste gas from the waste incinerator,
A topping turbine driven by steam generated by the boiler, and a topping generator for generating power in conjunction with the turbine, wherein the bottoming cycle unit generates heat of a low-boiling-point medium using exhaust gas of the topping turbine as a heat source. It is characterized by including an exchanger, a bottoming turbine driven by the generated low-boiling-point medium vapor, a bottoming generator that generates electric power in conjunction with the turbine, and a condenser that returns exhaust gas of the turbine to liquid.

Further, when the two-fluid waste power generation apparatus is applied to municipal solid waste power generation, the power generation efficiency is maximized for each substance of the low boiling point medium used under the condition that the steam temperature of the steam boiler is 300 ° C. or less. Physical conditions
We propose a two-fluid waste power generator that operates under these conditions.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of intensive studies on a waste power generation system capable of high-efficiency power generation, the present inventor has conceived a two-fluid waste power generation system in which a steam Rankine cycle and a low-boiling-point medium steam Rankine cycle are connected in series. And came up with a specific two-fluid waste power generation method and its device.

The direct trigger for creating the present invention is the above-described binary cycle power generation system in geothermal power generation. In this binary cycle power generation, as described above, power generation in the hot water stage is impossible, and the thermal energy of the hot water is transmitted to the low boiling medium to produce high pressure low boiling medium vapor, and this low boiling medium vapor Drives the steam turbine to generate electricity. That is, contrary to the name of binary cycle power generation, only one power generation is performed. If the former hot water stage in which power generation is not possible is replaced with a technically stable steam Rankine cycle having a long track record, power generation of the first stage is performed in this steam Rankine cycle section, and a low-boiling-point medium steam Rankine cycle is performed. A two-stage continuous power generation system in which the second-stage power generation is performed in the cycle unit can be realized.

After the first-stage power generation, the steam temperature is lowered but still in the intermediate temperature range. If the medium having a low boiling point lower than this temperature is forcibly evaporated, the second-stage power generation becomes possible. In municipal waste power generation, the boiler steam temperature has a limit of 300 ° C. However, if the selection of a low boiling point medium and the operating conditions are optimized, the heat of the steam can be efficiently converted to electricity in two stages. Becomes Even if there is a temperature limitation, increasing the boiler steam pressure can open the way to higher efficiency. Further, since the restriction may be loosened in the case of waste such as industrial waste, a higher-temperature steam boiler can be used, and the two-stage power generation system can be more effective.

In the present invention, the first-stage steam Rankine cycle is called a topping cycle, and the second-stage low-boiling-point steam Rankine cycle is called a bottoming cycle. First, in a topping cycle, high-temperature and high-pressure steam is generated by a steam boiler, and is adiabatically expanded by a topping turbine to perform first-stage topping power generation. As a result, the steam is changed to low-temperature and low-pressure steam. At this time, the inlet steam condition of the topping turbine is pressure P ₁ and temperature T _1, and the exhaust condition at the outlet is pressure P ₂ and temperature T ₂ . That is, the pressure drop by the turbine is given by P ₁ -P ₂ , and the temperature drop is given by T ₁ -T ₂ . In an approximation that ignores the loss due to the pipeline, (P ₁ , T
₁ ) can be the same as the output condition of the steam boiler, and (P ₂ , T ₂ ) can be the same as the input condition of the heat exchanger that generates the low-boiling-point medium steam.

Next, in the bottoming cycle, low-temperature, high-pressure, low-boiling-point medium vapor is formed through the heat exchanger by the heat of the exhaust steam having a temperature of about T ₂ , and is adiabatically expanded by the bottoming turbine to perform the second-stage bottoming. Generate electricity,
As a result, it is changed to a low-temperature, low-pressure, low-boiling medium vapor. Similarly, the inlet steam conditions of the bottoming turbine are pressure P ₃ and temperature T _3, and the exhaust conditions at the outlet are pressure P ₄ and temperature T ₄
And That is, the pressure drop by the bottoming turbine is P
₃ -P _4, the temperature drop becomes T ₃ -T _4.

In simple terms, the ideal condition with no line loss
In order to operate this power generation system under
T₁≦ 300 ℃, for evaporating low boiling medium
T_Two> T_Three, T_Three> Boiling point of low boiling point medium, bottoming power generation
T to increase efficiency_FourShould be lower. Also general
The inlet pressure P₁, P_ThreeIs high, exhaust pressure P_Two, P _Four
Is considered to be lower. Other related to power generation efficiency
The important physical quantity to be measured is the steam dryness of the topping exhaust
D2 and the temperature difference Δ between water and the low boiling point medium in the heat exchanger
There is T.

Firstly, the higher the topping inlet pressure P _1, it will be described with reference to FIG 1 that the topping power generation efficiency increases. Figure 1 is a Morie diagram showing the relationship between H and S, topping inlet pressure P ₁ is 5.0 MPa (solid line) and 3.0 MPa (short dashed line), topping the exhaust pressure P ₂
Is 118 kPa (solid line).
The portion of 3.0 MPa corresponds to FIG. 6, and the same symbols I, J, K, and f are used. Assuming that T ₁ = 295 ° C. for municipal solid waste power generation, at the intersections L and I between the isobaric heating line and the isotherm (dashed line), the point L is located to the left of the point I. When expanded by the topping turbine, it falls adiabatically to the points M and J, so that the thermal heads are F and f. Obviously, F> f, and the topping power generation efficiency is higher at 5.0 MPa. Therefore, it is important that the inlet pressure P ₁ be higher than the conventionally used 3.0 MPa.
This also the same in the bottoming cycle, it increases the efficiency of increasing the inlet pressure P _3.

The low boiling medium used in the present invention must have a boiling point lower than the topping exhaust temperature T ₂ . Organic media can be widely used as such a low-boiling medium. For example, propane (-42 ° C), allene (-3
4.5 ° C.), ammonia (−33.4 ° C.), isobutane (−10 ° C.), isobutylene (−6.9 ° C.), butane (−0.5 ° C.), ethyl methyl ether (6.4 ° C.),
Isoprene (34.1 ° C), ethyl ether (34.5)
° C), pentane (36 ° C), benzene (80.5 ° C) and the like. The number in parentheses is its boiling point.

When the low boiling point medium is specified, the final power generation efficiency of two-fluid municipal waste power generation, that is, the plant efficiency η (%) can be calculated from the physical properties based on the heat transfer theory. This heat transfer theory is a known theory, and will not be described in detail here. Assuming that the plant efficiency ηP ₁ on the topping side and the plant efficiency ηP ₂ on the bottoming side, ηP ₁ and ηP ₂ can be expressed by the following (1) and (2) ) Defined by the formula _{ηP 1 = (L 01 -L P1} -L P2) / Q 1 ... (1) ηP 2 = (L 02 -L P3) / Q 3 ... (2) However, in the (1) - (2) , L ₀₁ is the output of the topping generator (kJ / s), L ₀₂ is the output of the bottoming generator (kJ / s), L _P1 is the power of the boiler feed pump on the topping side (kJ / s), L _P2 is the topping Power of the deaerator feed pump on the side (kJ / s), L _P3 is the power of the feed pump on the bottoming side (kJ / s), Q ₁ is the heat input to the refuse incinerator (kJ / s), Q ₃ is The amount of heat input to the bottoming side (the amount of heat input to the heat exchanger) (kJ / s). Further, the plant efficiency η _P of the binary cycle obtained by combining the topping cycle and the bottoming cycle is defined by the following equation (3). _{η P = (ΣL 0 -ΣL P} ) / Q 1 = ηP 1 + ηP 2 · Q 3 / Q 1 ... (3) However, ΣL ₀ total generator output (kJ / s), ΣL _P is the total pump power ( kJ / s).

FIG. 2 shows that benzene (C
₆ H ₆ ), pentane (C ₅ H ₁₂ ), ammonia (N
The plant efficiency η with H ₃ ) and isobutane (C ₄ H ₁₀ ) is shown for the topping inlet steam pressure P ₁ . In FIG. 2, the symbol ◎ indicates the plant efficiency of the conventional plant. Except when the low-boiling-point medium is benzene, the plant efficiency η is a curve having an upward peak value. This is the topping steam pressure P ₁
Rise → increase in quantity of heat exchange to topping increase in steam flow → bottoming side → through the course of say an increase in the increase → bottoming output of the steam flow rate of the low-boiling medium, sequentially even plant efficiency η with increasing main steam pressure P ₁ of To rise. However, when the output of the bottoming generator rises to a certain level,
With the ratio of the pump power to total output of bottoming generator becomes large, because the output of the topping generator decreases with increasing of the main steam pressure P _1, as a result, the plant efficiency η from the middle as shown in FIG. 2 It becomes the curve of the state of going down right. Incidentally, when the low-boiling medium is benzene, although plant efficiency η as described above has a upward-sloping curve, which is topped main steam pressure P _1, the steam temperature T
Saturation pressure (about 8 MPa) at the maximum value of ₁ (about 300 ° C)
It is because it is restricted by.

As shown in FIG. 2, all four plant efficiencies result in curves with peaks at the top, with the peak giving maximum efficiency. In terms of peak value, benzene was 19.7.
%, 19.0% for pentane, 18.4% for ammonia,
It becomes 17.7% with isobutane. It has been difficult for the conventional one-fluid municipal waste power generation to have a plant efficiency exceeding 18%, but in the present invention, it is possible to exceed 18% as originally expected. Isobutane does not exceed 18%, but the two fluids easily reach almost the highest values of the prior art devices. In general, it is quite difficult to increase the power generation efficiency by 1%, but in the present invention, it can be easily exceeded.

The results obtained from the calculation results and the vicinity of the peak in FIG.
More detailed high-efficiency municipal solid waste power generation conditions, theoretical plan
The following are from the low-boiling medium with high heat efficiency. First, a low-boiling medium
When using benzene as the topping turbine
Pressure P as inlet steam condition₁= 6.5-8.2MP
a, temperature T₁Of the top = 300 ° C
Pressure P_Two= 1.0-2.5MP
a, steam dryness D2 = 88% or more, water in heat exchanger
Temperature difference ΔT = 5-30 ° C.
Pressure P_Three= 0.2-
1.5MPa, temperature T_Three= Saturated steam temperature, Botomin
Using an air-cooled condenser as exhaust conditions for g turbines
Pressure P_Four= Saturated vapor pressure, temperature T_Four= 55-80
° C, pressure P when using a water-cooled condenser_Four= Saturated
Vapor pressure, temperature T _Four= 30-50 ° C operating conditions
Light range.

When pentane is used as the low boiling point medium, the pressure P _{1 is set} as the inlet steam condition for the topping turbine.
= 5.7-7.7 MPa, maximum value of temperature T ₁ = 300 ° C.
And the pressure P ₂ =
300-700 kPa, steam dryness D2 = 88% or more, temperature difference ΔT = 5 between water and low boiling point medium in heat exchanger
30 ° C., the pressure P ₃ = 0.7 to 3.0 MPa, the temperature T ₃ = saturated steam temperature as the inlet steam condition for the bottoming turbine, and the pressure P ₄ = when using an air-cooled condenser as the exhaust condition for the bottoming turbine. saturated vapor pressure, the temperature T ₄ = 55 to 80 ° C., the pressure P ₄ = saturation vapor pressure in the case of using a water-cooled condenser, operating conditions and the temperature T ₄ = 30 to 50 ° C. is in the range of the present invention.

When ammonia is used as the low boiling point medium, the pressure P
₁ = 4.5 to 5.5 MPa, maximum value of temperature T ₁ = 300
° C and the pressure P ₂ as the exhaust condition of the topping turbine.
= 70-200 kPa, steam dryness D2 = 88% or more, and temperature difference ΔT = 5 between water and low boiling point medium in the heat exchanger.
30 ° C., pressure P ₃ = 4.0-7.0 MPa as inlet steam conditions for the bottoming turbine, temperature T ₃ = saturated steam temperature, and pressure P ₄ = when using an air-cooled condenser as the exhaust condition for the bottoming turbine. saturated vapor pressure, the temperature T ₄ = 55 to 80 ° C., the pressure P ₄ = saturation vapor pressure in the case of using a water-cooled condenser, operating conditions and the temperature T ₄ = 30-45 ° C. is in the range of the present invention.

When isobutane is used as the low boiling point medium, the pressure P
₁ = 4.5 to 5.5 MPa, maximum value of temperature T ₁ = 300
° C and the pressure P ₂ as the exhaust condition of the topping turbine.
= 70-200 kPa, steam dryness D2 = 88% or more, and temperature difference ΔT = 5 between water and low boiling point medium in the heat exchanger.
30 ° C., pressure P ₃ = 1.1 to 2.2 MPa, temperature T ₃ = saturated steam temperature as inlet steam conditions for the bottoming turbine, and pressure P ₄ = when an air-cooled condenser is used as exhaust conditions for the bottoming turbine. saturated vapor pressure, the temperature T ₄ = 55 to 80 ° C., the pressure P ₄ = saturation vapor pressure in the case of using a water-cooled condenser, operating conditions and the temperature T ₄ = 30 to 50 ° C. is in the range of the present invention.

The above operating condition is that the boiler steam temperature is 300 ° C.
The present invention relates to a two-fluid municipal solid waste power generator limited to the following, and is not necessarily a condition that gives maximum efficiency in waste such as industrial waste and public waste. But,
Even if the conditions are changed, it goes without saying that a two-fluid waste power generation system can achieve high efficiency for general waste. The only reason is that, in addition to the topping power generation using steam, the low-boiling-point medium is changed to high-pressure steam using exhaust steam having a lowered temperature, and bottoming power generation is performed using the low-boiling-point medium steam. In other words, while the conventional power generation ends with only the topping power generation, if the remaining energy is considered as the bottoming power generation, the reason why the power generation efficiency is increased can be understood.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the two-fluid waste power generation apparatus according to the present invention will be described below for each low-boiling medium. In the present embodiment, the municipal solid waste is targeted, and hence is referred to as a two-fluid type municipal solid waste generation device.

Example 1 Two-Fluid Water-Ammonia System FIG. 3 is a block diagram of a two-fluid type municipal solid waste power generator when ammonia is used as a low-boiling-point medium. Is shown. This power generation device is configured by connecting a topping cycle unit TP and a bottoming cycle unit BP in series. Topping cycle part TP is incinerator 1,
Steam boiler 2, boiler feed pump 3, plant 4, topping turbine 5a, topping generator 6a, deaerator 1
1. It is composed of a water supply pump 13. The bottoming cycle section BP includes a bottoming turbine 5b, a bottoming generator 6b, a heat exchanger 12, a condenser 14, a feedwater pump 15, and a condensate heater 16.

Next, the operation of the above configuration will be described. First, the municipal solid waste A is burned in the incinerator 1, and the combustion exhaust gas of about 900 ° C. is sent to the steam boiler 2, and the water supplied from the boiler suction pump 3 is heated to high temperature and high pressure (about 300 ° C., 5.
Heat to 1 MPa) steam. A part of the steam is sent to the plant 4 and used for preheating the air of the incinerator 1 and reheating the exhaust gas.
Reflux. The other steam is sent to the topping turbine 5a, which is a bleed / back-pressure steam turbine, and the topping generator 6a performs first-stage topping power generation. A part of the steam is extracted from the topping turbine 5a and sent to the deaerator 11 for heating. A large amount of exhaust steam having a pressure of 119 kPa is guided to the heat exchanger 12 and used for generating steam of ammonia, becomes saturated water, returns to the deaerator 11 by the feed water pump 13, and completes the topping cycle. Makeup water B is supplied to the deaerator 11 to keep the water in the topping cycle section TP constant.

On the other hand, the low-temperature, high-pressure (94.5 ° C., 5.6 MPa) ammonia vapor generated in the heat exchanger 12 drives the bottoming turbine 5b, which is a condensing steam turbine, and turns the generator 6b to produce the second steam. Staged bottoming power generation is performed. The ammonia vapor discharged from the turbine becomes a saturated liquid by the condenser 14 and is returned to the heat exchanger 12 via the feed water pump 15 and the condensate heater 16 to complete the bottoming cycle. The condensate heater 16 supplies ammonia condensate at the outlet of the condenser 14 to the bottoming turbine 5.
The heating is performed by the extraction of b, and the regeneration cycle is used to improve the power generation efficiency. Further, two types of condensers 14 of an air-cooled type and a water-cooled type can be used. In this embodiment, an air-cooled type is used.

Various physical quantities and calculation results used in Example 1 are summarized in Tables 1 and 2. Plant efficiency η
(%) Is calculated by the following equation. η = (power output-pump power) / heat input to municipal waste x 1
00 (%) In Example 1, the plant efficiency η was 18.35%. While the conventional apparatus did not exceed 18%, the first embodiment achieved a good result exceeding 18%.

Example 2 Water-Pentane Two Fluids FIG.
Is a configuration diagram of a two-fluid type municipal waste power generation device when pentane is used as a low boiling point medium, and is basically the same as FIG. Accordingly, only the differences will be described.
b, the entire amount of exhaust gas is sent to the condensate heater 16 and the condenser 1
At the same time, the preheating is performed at the same time as the condensing in step 4. The other configuration and operation are the same as those in FIG. 3, and the description thereof will be omitted.

The steam temperature at the outlet of the steam boiler 2 is 300
° C, the pressure is 6.9 MPa, the temperature of pentane vapor at the outlet of the heat exchanger 12 is 153.3 ° C, and the pressure is 1.7 MPa.
a. Along with these values, other physical quantities and calculation results are described in Tables 1 and 2. For example, in the column of Example 2 (low-boiling medium ... pentane) in Table 2,
The generator output of the bottoming cycle is calculated to be 3280 kW, and this generator output is calculated by the following various quantities. That is, the inlet steam pressure P ₃ = 1.6 MPa to the bottoming turbine, and the inlet steam temperature T ₃ = 149.9.
° C, inlet steam flow rate = 195200 kg / h, exhaust pressure P
_{When 4} = 184 kPa and the exhaust gas temperature T ₄ = 99.8 ° C, the turbine inlet (P ₃ · T ₃ ... Maurie) The enthalpy H ₁ of pentane vapor at the point L in the diagram is 673.5 kJ / kg, and the exhaust port (P ₄ · T ₄ ... J in the Maurier diagram)
Enthalpy H ₂ of pentane vapor at
9.8 kJ / kg (the enthalpy H ₂ ′ at point M in the Maurier diagram is 589.7 kJ / kg). Therefore, the output P ₂ of the bottoming turbine generator is P ₂ = 195200 kg / h × (673.5-609.
8) kJ / kcal × 0.95 / 860 kcal / kW
× 4.2 kJ / kcal = 3,280 kW. Further, when the plant efficiency η was calculated using the above equation (3), the plant efficiency η of Example 2 was 18.98%. The efficiency is even higher than ammonia, demonstrating the effectiveness of the present invention.

Example 3 Water-Benzene Two Fluids Example 3 is a two-fluid municipal solid waste power generator in which benzene is used as a low-boiling-point medium. The structure is the same as that of FIG. 4 except that the working medium is different. . Therefore, description of the configuration and operation will be omitted.

The steam temperature at the outlet of the steam boiler 2 is 300
° C, the pressure was 8.1 MPa, the temperature of benzene vapor at the outlet of the heat exchanger 12 was 202.2 ° C, and the pressure was 1.49M.
Pa. Other physical quantities and calculation results are shown in Tables 1 and 2. Plant efficiency η of Example 3
Was 19.72%. Benzene has the highest efficiency and clarifies the effectiveness of the two-fluid municipal solid waste generator.

[Conventional Example: Conventional Method of Single-Water Fluid] For comparison with the first to third embodiments, a similar test was performed on the conventional single-fluid municipal solid waste generator shown in FIG. The results are shown in Tables 1 and 2. 17.57% plant efficiency
, Which is the highest performance among the conventional devices.
-3 was the lowest.

The preconditions for the calculations in Tables 1 and 2 are as follows. Incinerator 1 is 350 tons / day and heat input is 30
Gcal / h. The amount of heat absorbed by the steam boiler 2 is 87% of the amount of heat input into the refuse. The steam heat of the plant 4 is 10% of the heat input of the refuse, that is, 3 Gcal / h. Turbine 5
The internal efficiency of a and 5b is 76%, and the efficiency of the generators 6a and 6b is 95%. The bleed pressure of the turbines 5a and 5b is set to 0.
9MPa, main steam temperature at outlet of steam boiler 2 is 300 ° C,
The final exhaust temperature of the air-cooled condenser 14 is 55 ° C.

[0045]

[Table 1]

[0046]

[Table 2]

As is clear from Tables 1 and 2, when the efficiency of the conventional example is 1.0, the output ratios of Examples 1 to 3 are 1.044, 1.080 and 1.12. Therefore, a two-fluid power generation system in which water and a low-boiling-point medium are connected can make a great contribution to increasing the power generation efficiency.

The present invention is not limited to the above-described embodiment, but includes various modifications and design changes within the technical scope thereof without departing from the technical concept of the present invention.

[0049]

As described in detail above, the present invention has completed a two-fluid waste power generation method and its apparatus in which a steam Rankine cycle and a low-boiling medium steam Rankine cycle are connected in series. The heat of combustion of waste such as industrial waste can be efficiently converted to electric power.
In particular, in the case of municipal solid waste power generation using organic media such as ammonia, isobutane, pentane, and benzene, the operating conditions that maximize the power generation efficiency of the two-fluid system could be specified, realizing a practical plant. Has the effect.

[Brief description of the drawings]

FIG. 1 is a Maurier diagram illustrating the relationship between enthalpy H and entropy S in the present invention.

FIG. 2 is a diagram showing the relationship between the theoretical plant efficiency of benzene, pentane, ammonia, and isobutane and the steam pressure at the topping turbine inlet.

FIG. 3 is a configuration diagram of a two-fluid municipal solid waste power generation device when ammonia is used as a low-boiling-point medium in the present invention.

FIG. 4 is a configuration diagram of a two-fluid municipal waste power generation device when pentane or benzene is used as a low-boiling-point medium in the present invention.

FIG. 5 is a configuration diagram of a conventional one-fluid municipal waste power generation device using water.

FIG. 6 is a Maurier diagram illustrating the relationship between enthalpy H and entropy S in a conventional example.

[Explanation of symbols]

A is municipal waste, B is makeup water, TP is a topping cycle section, BP is a bottoming cycle section, 1 is an incinerator, 2 is a steam boiler, 3 is a boiler feed pump, 4 is a plant, 5 is a steam turbine, and 5a is a topping. Turbine, 5b: bottoming turbine, 6: generator, 6a: topping generator, 6b: bottoming generator, 7: ejector, 8: condenser, 9: condensate pump, 10: ejector vapor condenser, 11: degassing , 12 is a heat exchanger, 13 is a feedwater pump, 14 is a condenser, 15 is a feedwater pump, and 16 is a condensate heater.

Claims (6)

[Claims] 1. A topping cycle section in a preceding stage for performing a Rankine cycle using steam as a working medium and a bottoming cycle section in a latter stage for performing a Rankine cycle using low-boiling-point medium steam as a working medium are connected in series to discharge a waste incinerator. High-temperature, high-pressure steam is generated by heat, and the topping cycle is operated using this steam to generate topping power. As a result, the low-temperature, high-pressure low-boiling medium steam is exchanged with the relatively low-temperature, low-pressure steam. A two-fluid waste power generation method characterized in that bottoming power is generated by operating a bottoming cycle using the generated low-boiling-point medium vapor. 2. A topping cycle section in a preceding stage for performing a Rankine cycle using steam as a working medium and a bottoming cycle section in a latter stage for performing a Rankine cycle using low boiling medium steam as a working medium are connected in series, and the topping cycle section is discarded. A steam boiler for recovering heat from exhaust gas from a waste incinerator, a topping turbine driven by steam generated by the boiler, and a topping generator for generating power in conjunction with the turbine, wherein the bottoming cycle section includes the topping turbine. A heat exchanger that generates steam of a low-boiling medium by using the exhaust gas as a heat source, a bottoming turbine driven by the generated low-boiling-point medium steam, a bottoming generator that generates electric power in conjunction with the turbine, and an exhaust gas of the turbine. Two-fluid disposal comprising a condenser returning to liquid Power generator. 3. In power generation using municipal solid waste as waste, ammonia is used as a low-boiling-point medium, and pressure P ₁ = 4.5-5.
5 MPa, the maximum value of the temperature T ₁ = 300 ° C., and the pressure P ₂ = 70 to 200 k as the exhaust condition of the topping turbine.
Pa, steam dryness D1 = 88% or more, temperature difference ΔT = 5-30 ° C. between water and low boiling point medium in the heat exchanger, and pressure P ₃ = 4.0 as inlet steam conditions for the bottoming turbine.
７7.0 MPa, temperature T ₃ = saturated steam temperature, and when using an air-cooled condenser as the exhaust condition of the bottoming turbine, pressure P ₄ = saturated steam pressure, temperature T ₄ = 55-8.
3. The two-fluid waste power generator according to claim 2, wherein the two-fluid waste power generator is operated under the operating conditions of 0 ° C., pressure P ₄ = saturated vapor pressure, and temperature T ₄ = 30 to 45 ° C. when a water-cooled condenser is used. 4. In power generation using municipal solid waste as waste, isobutane is used as a low-boiling-point medium, and pressure P ₁ = 4.5-5.
5 MPa, the maximum value of the temperature T ₁ = 300 ° C., and the pressure P ₂ = 70 to 200 k as the exhaust condition of the topping turbine.
Pa, steam dryness D1 = 88% or more, temperature difference ΔT = 5-30 ° C. between water and low boiling point medium in heat exchanger, pressure P ₃ = 1.1 as inlet steam condition for bottoming turbine.
２2.2 MPa, temperature T ₃ = saturated steam temperature, and when using an air-cooled condenser as the exhaust condition of the bottoming turbine, pressure P ₄ = saturated steam pressure, temperature T ₄ = 55-8.
3. The two-fluid waste power generator according to claim 2, wherein the two-fluid waste power generator is operated under the operating conditions of 0 ° C., pressure P ₄ = saturated vapor pressure, and temperature T ₄ = 30 to 50 ° C. when a water-cooled condenser is used. 5. In power generation using municipal solid waste as waste, pentane is used as a low-boiling medium, and pressure P ₁ = 5.7 to 7.7 is set as inlet steam conditions for a topping turbine.
MPa, the maximum value of the temperature T ₁ = 300 ° C., and the pressure P ₂ = 300 to 700 k as the exhaust condition of the topping turbine.
Pa, steam dryness D1 = 88% or more, temperature difference ΔT = 5-30 ° C. between water and low boiling point medium in the heat exchanger, and pressure P ₃ = 0.7 as inlet steam conditions for the bottoming turbine.
３3.0 MPa, temperature T ₃ = saturated steam temperature, and when using an air-cooled condenser as the exhaust condition of the bottoming turbine, pressure P ₄ = saturated steam pressure, temperature T ₄ = 55-8.
3. The two-fluid waste power generator according to claim 2, wherein the two-fluid waste power generator is operated under the operating conditions of 0 ° C., pressure P ₄ = saturated vapor pressure, and temperature T ₄ = 30 to 50 ° C. when a water-cooled condenser is used. 6. In power generation using municipal solid waste as waste, benzene is used as a low-boiling medium, and pressure P ₁ = 6.5 to 8.2 as inlet steam conditions for a topping turbine.
MPa, the maximum value of the temperature T ₁ = 300 ° C., and the pressure P ₂ = 1.0 to 2.5 M as the exhaust condition of the topping turbine.
Pa, steam dryness D1 = 88% or more, and heat exchanger 12
Temperature difference between water and the low boiling point medium ΔT = 5 to 30 ° C.,
Pressure P ₃ =
0.2 to 1.5 MPa, temperature T ₃ = saturated steam temperature,
When an air-cooled condenser is used as the exhaust condition of the bottoming turbine 5b, the pressure P ₄ = saturated vapor pressure, the temperature T ₄
3. The two-fluid waste power generation apparatus according to claim 2, which is operated under operating conditions of: 55 to 80 ° C., pressure P ₄ = saturated vapor pressure, and temperature T ₄ = 30 to 50 ° C. when a water-cooled condenser is used.