CN107327326A - A kind of integral combined circulating power generation system of integrated garbage gas steam - Google Patents

Abstract

The invention discloses an overall combined cycle power generation system integrating garbage-gas-steam, which includes a garbage incinerator, a waste heat boiler, a compressor, a combustion chamber, a turbine, a steam turbine and a generator connected in sequence; the outlet steam of the garbage incinerator and the The steam with similar temperature in the waste heat boiler is mixed and enters the high temperature section of the waste heat boiler for heating and superheating. Using the high temperature flue gas at the outlet of the turbine as a heat source, the mixed steam in the heat recovery boiler enters the steam turbine to do work, and the exhaust steam after work is condensed into water and then enters the Waste heat boiler and waste incinerator constitute a thermal cycle. The invention turns discarded garbage into an energy source, complements multiple sources, improves the parameters of the steam generated by the garbage incinerator in the waste heat boiler, improves the thermal efficiency and power of the steam generated by the garbage incinerator in the steam cycle power generation, and avoids the incineration of the incinerator at the same time. The problem of aggravated corrosion under high temperature conditions, prolonging the life of the waste incinerator, has the characteristics of high operational reliability and low pollutant discharge.

Description

An overall combined cycle power generation system integrating garbage-gas-steam

technical field

The invention relates to an integrated combined cycle power generation system with multiple sources (energy sources of garbage, gas and steam) complementary, in particular to an integrated combined cycle power generation system integrating garbage, gas and steam.

Background technique

With the continuous advancement of my country's urbanization process, the garbage generated in cities is also increasing, and the problem of garbage disposal is imminent. According to relevant data, my country's urban waste is increasing at an annual growth rate of 8-10%, while at the same time, the growth rate of waste disposal lags behind the speed of waste production. Garbage has encroached on and polluted large areas of land in the suburbs of cities, and the city is besieged by garbage. The phenomenon is serious, and about 1/3 of the cities in our country are surrounded by garbage. There are no more than three methods of garbage disposal: landfill, composting, and incineration for power generation. Landfill treatment occupies a large amount of land resources, which is likely to cause soil and water pollution. Among them, methane and other gases produced by landfill fermentation can easily cause fires and greenhouse effects. Composting is costly with little reduction. At the same time, the processing cycle of both is long, which makes it difficult to adapt to the current urban development requirements. Compared with the former two, incineration power generation has the characteristics of small footprint, high degree of reduction, small impact on the environment, and recycling of resources. The national "Twelfth Five-Year Plan" lists waste incineration as a priority area for development.

Since our country has not really implemented garbage classification in an all-round way, the garbage is always in a state of mixed collection, resulting in a low average calorific value of the garbage, and at the same time it contains more chlorine, alkali metals, sulfur and other components, which are likely to cause corrosion of the incinerator , affecting the life and operation safety of the unit, especially on units with higher parameters, such as the Guangzhou Likeng waste incineration power plant that uses sub-high temperature and high pressure. Therefore, in order to reduce corrosion, waste incinerators are generally limited to medium-temperature and medium-pressure boilers, and their main steam parameters are 4MPa/400°C. In order to prevent low-temperature corrosion at the outlet of the waste incinerator, the exhaust gas temperature is relatively high. The triple impact of lower waste calorific value and main steam parameters and higher exhaust gas temperature makes its power generation efficiency only about 10-20%. On the premise of reducing equipment corrosion and operating safely, how to further improve the efficiency of waste incineration power generation system is imminent.

Patent literature (US Patent of Invention, Application Publication No. US005724807A, Application No. 790247) discloses a garbage-gas turbine combined cycle power generation system. This garbage-gas turbine combined cycle power generation system consists of a gas turbine, a garbage incinerator, and a steam turbine. The purpose is to increase the steam temperature at the outlet of the waste incinerator while reducing the high temperature corrosion of the waste incinerator. The way to achieve this is to use the high-temperature gas discharged from the gas turbine to superheat the steam generated by the waste incinerator, and the high-temperature steam generated enters the steam turbine to do work. Air. The power generation system increases the temperature of the steam, increases the working capacity of the steam turbine, and also improves the thermal efficiency of the steam power generation system generated by the waste incinerator, avoiding the problem of aggravated corrosion of the incinerator due to the increase in the temperature of the steam, and extending the life of the waste incinerator It will not be shortened by increasing the temperature of the steam. The whole system is compact and occupies a relatively small area.

However, as mentioned above, the high-temperature gas discharged from the gas turbine is used to heat the steam generated by the waste incinerator, and after it is overheated, it is used to heat the feed water and air entering the incinerator. Because the temperature difference between the gas and the feed water and air entering the incinerator is large large, caused by heat transfer From the point of view of rational and comprehensive energy utilization according to energy grades, such a configuration method is very unreasonable, and the real cascade utilization of energy according to grades has not been realized.

The patent literature (US Patent of Invention, Application Publication No. US6604354B2, Application No. 09/988,143) discloses a combined cycle power generation system for retrofitting existing low-capacity steam cycle power generation units. This patent is also applicable to waste incineration steam cycle power generation units. This combined cycle power generation system consists of a gas turbine, a waste heat boiler, a steam turbine and an existing low-capacity boiler. The purpose is to solve the problems of low power and low thermal efficiency of the currently operating steam cycle generator sets, which are facing elimination, and use the high cycle thermal efficiency of the gas-steam combined cycle to improve the power and thermal efficiency of the entire device to achieve high efficiency, environmental protection and economical operation. The steam generated by the waste heat boiler and the steam generated by the operating boiler are mixed together and enter the steam turbine to do work, and the exhausted steam after the work is condensed and pressurized, and then enters the waste heat boiler and the currently operating boiler. The steam turbine and the gas turbine respectively drive generators to generate electricity. The system improves the output of the whole device, and the system is simple, while reducing the number of steam turbines, avoiding the extra high equipment cost and construction cost brought by the new power plant.

As mentioned above, this combined cycle power generation system simply mixes the steam from the waste heat boiler and the existing boiler, and does not improve the main steam parameters at the outlet of the currently operating boiler, and the efficiency of the currently operating steam power generation system has not been improved. At the same time, because the parameters of the two steams are prone to temperature deviation and pressure difference during operation, the operation during mixing is difficult and inconvenient to operate, and once the parameters of the two steams deviate during operation, simple mixing will increase the irreversible loss and increase the energy. Depreciation, the thermal efficiency of the whole device decreases. In addition, this method also limits the optimal selection of steam parameters at the outlet of the waste heat boiler of the newly added combined cycle power generation system, so that it must be consistent with the steam parameters of the boiler outlet of the original low-capacity steam cycle power generation unit, which is not conducive to comprehensive With the optimal selection of the parameters of each component, the entire device has not reached the optimal matching of parameters, and the thermal efficiency is not optimal. In addition, due to the increase in steam flow, the original steam turbine also needs to be expanded and replaced.

Contents of the invention

For the garbage-gas turbine combined cycle power generation system of Patent Document 1 (Application Publication No. US005724807A), although it can avoid the aggravation of high-temperature corrosion of the garbage incinerator, the lifespan is not shortened, the initial temperature of the steam cycle increases, and the working capacity of the steam turbine increases. The thermal efficiency is improved, the system is compact, etc., the gas is used to heat the feed water and air entering the incinerator, but due to the large temperature difference between the gas and the feed water and air entering the incinerator, the heat transfer caused From the point of view of reasonable and comprehensive energy consumption according to the energy grade, such a configuration method is very unreasonable, and the utilization rate of gas energy is low. Patent Document 2 (Application Publication No. US6604354B2) aims at the problem of low power and low thermal efficiency of the currently operating steam cycle power generating units, which are faced with the problem of elimination. , the system is simple, and the number of steam turbine configurations is reduced at the same time, which avoids the extra high equipment and construction costs brought about by the new power plant. However, due to the temperature deviation and pressure difference between the two steam parameters during operation, it is more difficult to operate during mixing. Large, inconvenient operation, and simple mixing will increase the irreversible loss, the energy of the mixed steam at the outlet of the waste heat boiler will depreciate, and the thermal efficiency of the entire device will decrease. In addition, due to the increase in steam flow, the original steam turbine also needs to be expanded and replaced; and the main steam parameters at the outlet of the currently operating boiler have not been improved, and the efficiency of the currently operating steam power generation system has not been improved. In view of the problems existing in the above patents, the present invention provides a comprehensive combined cycle power generation system of garbage-gas-steam that is complementary and integrated with multiple sources (garbage, gas, and steam energy) to improve the thermal efficiency and energy of the steam cycle power generation generated by garbage incineration. The cascades are rationally used to realize the safe, efficient and environmentally friendly operation of the unit. The system consists of gas turbine, waste heat boiler, steam turbine, waste incinerator and related flue gas treatment equipment and auxiliary equipment. The steam at the outlet of the waste incinerator and the steam at a similar temperature in the waste heat boiler are mixed together and enter the high temperature section of the waste heat boiler for heating. The heated mixed steam enters the steam turbine to do work. form a thermal cycle. The steam turbine and the gas turbine respectively drive the generator to generate electricity and realize the grid-connected operation with the outside world.

The gas-steam combined cycle power generation system has the characteristics of short construction period, low investment, high operation reliability, and low pollution emissions. Due to the combination of Brayton and Rankine cycles, its energy can be utilized in steps and the power generation efficiency is high. The exhaust gas temperature of the gas turbine is 550-650°C, and the temperature of the main steam of the medium-temperature and medium-pressure incinerator is 400°C. In the waste heat boiler, the exhaust gas of the turbine is used to further heat the main steam of the incinerator to improve the waste incinerator. The main steam parameters improve the thermal efficiency and power of the steam cycle power generation generated by the waste incinerator, and at the same time avoid the problem of intensified corrosion of the incinerator under high temperature conditions and prolong the life of the waste incinerator. Due to the installation of the waste heat boiler, the heat transfer temperature difference between the gas and the steam in the waste heat boiler is small, and the heat transfer The loss is small, and the energy cascade utilization is realized. At the same time, the system is generally located in the suburbs of the city, which is conducive to the effective integration of resources, turning waste garbage into energy, compact integration of waste incineration units and gas-steam combined cycle units, reducing the number of steam turbines and generators and other equipment, making the area occupied Relatively small, less investment, high equipment utilization.

In order to achieve the above object, the concrete technical scheme that the present invention adopts is as follows:

An overall combined cycle power generation system integrating garbage-gas-steam, including a garbage incinerator, a waste heat boiler, and a compressor, a combustion chamber, a turbine, a steam turbine and a generator connected in sequence; the outlet steam of the garbage incinerator and the waste heat boiler The steam with similar temperature is mixed and enters the high-temperature section of the waste heat boiler for heating and superheating. The high-temperature flue gas from the turbine outlet is used as a heat source to heat the mixed steam in the waste heat boiler and enter the steam turbine to do work. The exhaust steam after work is condensed into water and then enters the waste heat boiler and The waste incinerator constitutes a thermal cycle.

In the present invention, in the third superheater of the high-temperature section of the waste heat boiler, the parameters of this part of the steam generated by the waste incinerator are increased, and the thermal efficiency and power of this part of the steam generated by the waste incinerator in the steam cycle power generation are improved, and at the same time, the incinerator is avoided. The problem of aggravated corrosion at high temperature prolongs the life of the waste incinerator.

Preferably, the steam turbine has a high-pressure cylinder, a medium-pressure cylinder and a low-pressure cylinder connected coaxially in sequence.

As preferably, the first economizer, the first evaporator and the first superheater connected in sequence are set in the garbage incinerator, and the part of the condensed water after the steam turbine works passes through the first economizer, the first evaporator and the first superheater successively. After the first superheater, the outlet steam of the waste incinerator is formed.

Preferably, a second economizer, a second evaporator, a second superheater, a reheater and a third superheater are installed in the waste heat boiler, wherein the second economizer, the second evaporator and the second The superheaters are connected in sequence, the outlets of the first superheater and the second superheater are respectively connected to the inlet of the third superheater through pipes, the outlet of the third superheater is connected to the high-pressure cylinder, and the outlet of the high-pressure cylinder is connected to the inlet of the reheater , the outlet of the reheater is connected to the inlet of the medium-pressure cylinder, and the outlet of the medium-pressure cylinder is connected to the inlet of the low-pressure cylinder through pipes;

A condenser and a feedwater pump are connected in sequence at the outlet of the low-pressure cylinder for condensing exhaust steam after the steam turbine has done work into water and sending it to the first economizer and the second economizer.

Preferably, the integrated combined cycle power generation system operates in parallel with the external power grid.

The advantages of the present invention are: the system is generally located in the suburbs of the city, which is beneficial to the effective integration of resources, turning waste garbage into energy, multi-source (garbage, gas, steam energy) complementary, garbage incineration unit and gas-steam combined cycle unit Compact integration reduces the number of equipment such as steam turbines and generators, resulting in a relatively small footprint, low investment, and high equipment utilization. Further improve the main steam parameters generated by the waste incinerator, improve the thermal efficiency and power of the steam generated by the waste incinerator in the steam cycle power generation, and at the same time avoid the problem of intensified corrosion of the incinerator under high temperature conditions, and prolong the life of the waste incinerator. Due to the installation of the waste heat boiler, the thermal energy cascade can be rationally utilized by rationally designing the heat exchange mode. The heat transfer temperature difference between the flue gas and the steam in the waste heat boiler is small, and the heat transfer The loss is small, and the energy cascade utilization is realized. The system also has the characteristics of high operational reliability and less pollutant discharge.

Description of drawings

Fig. 1 is a diagram of an overall combined cycle power generation system integrating garbage-gas-steam in the present invention.

detailed description

The present invention will be more fully described with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. In fact, the present invention can be embodied in many different forms, and can be applied to power generation in different forms such as single pressure, double pressure, triple pressure, with or without reheating, natural circulation, control circulation, direct current, single shaft, multi-shaft, etc. system. It should not be construed as limited to the embodiments set forth herein; rather, the embodiments of the invention should be considered as provided so that this disclosure will satisfy applicable legal requirements. This embodiment further describes the substantive features of the present invention in conjunction with the accompanying drawings and specific implementation methods of the description below:

The integrated garbage-gas-steam overall combined cycle power generation system diagram is shown in Figure 1. Its working process and principle are as follows: the air in the atmospheric environment is filtered and then enters the compressor 1 for compression and boosting, and the generated high-pressure air enters the combustion chamber. The fuel is mixed and burned in the chamber 2, and the high-temperature and high-pressure gas generated enters the turbine 3 to convert heat energy into mechanical energy. The flue gas discharged from the turbine 3 enters the waste heat boiler 4, which is equipped with a second economizer 5, a second evaporator 6, a second superheater 7, a third superheater 9 and a reheater 8, and the waste heat boiler 4 The water in the flue gas absorbs most of the heat. The flue gas is discharged from the waste heat boiler 4 and enters the flue gas treatment equipment, and is discharged into the atmosphere after being treated.

Garbage enters the incinerator 10 and burns under the cooperation of the primary and secondary air. The solid waste generated is discharged from the lower end of the furnace, and the high-temperature flue gas generated passes through the first evaporator 12, the first superheater 13 and the second evaporator in the furnace. The economizer 11 exhausts the smoke into the atmosphere after passing through the flue gas treatment equipment. The water pressurized by the water pump 14 enters the second economizer 5 in the waste heat boiler 4 and the first economizer 11 in the waste incinerator 10 respectively. The water entering the second economizer 5 passes through the second evaporator 6 and the second superheater 7 in turn to form higher temperature steam. At the same time, the water entering the first economizer 11 passes through the first evaporator 12 and the first superheater 13 in turn to form higher temperature steam. After the water vapor produced by the two is mixed, it enters the third superheater 9 together for superheating, produces higher temperature superheated steam, enters the high-pressure cylinder 16 of the steam turbine to do work, and the water vapor at the outlet of the high-pressure cylinder enters the reheater 8 of the waste heat boiler Reheating, the temperature of the water vapor generated by the reheater 8 is close to the temperature of the main steam, and then the water vapor at the outlet of the reheater 8 enters the medium-pressure cylinder 17 and the low-pressure cylinder 18 to do work, and the exhausted steam in the low-pressure cylinder 18 of the steam turbine enters the condensing steam 15 condenses into liquid water, and the liquid water is sent to the feed pump 14 for pressurization, wherein the net output of the turbine 3 and the output of the high-pressure cylinder 16, medium-pressure cylinder 17 and low-pressure cylinder 18 of the steam turbine jointly drive the generator 19 to generate electricity. This completes the cycle and generates electricity.

In the following, the parameters of a gas-steam combined cycle generator set and a sub-high temperature and high pressure 6.5MPa/450℃ waste incineration generator set that processes 450t of garbage per day will be calculated and analyzed.

Table 1 Parameters of a gas-steam combined cycle generator set

Table 2 Parameters of waste incinerator power generation system

①Traditional gas-steam combined cycle generator set and waste incineration generator set separate system:

For the gas-steam combined cycle generator set, it can be obtained from the heat balance that the heat absorbed by the water vapor is equal to the heat difference between the inlet and outlet of the waste heat boiler, then:

Calculate the water vapor flow rate m _stream1 = 96.613kg/s

Then the work done by the steam turbine:

P _st1 ＝m _stream1 [(h _hs1 -h _hs2 )+(h _re -h _ls2 ]/1000 (2)

Get P _st1 = 147MW;

For waste incineration power generation units, the total heat of the boiler is obtained from the heat balance equation:

Heat absorbed by water vapor:

Q _ws = Q _w η _z (4)

Calculate Q _w =44.528MW, Q _ws =36.657MW.

Then the work done by the steam turbine is:

P _st2 ＝m _stream [(h _hs1 -h _hs2 )+(h _re -h _ls2 ]/1000 (5)

Obtain the work P _st2 of the steam turbine of the waste incinerator = 11.264MW;

Assume that the mechanical efficiency η _m of the unit is 0.99, and the generator efficiency η _g is 0.96.

Total output of discrete system:

P _e1 ＝(P _gt +P _st1 +P _st2 )η _m η _g (6)

The total output P _e1 = 402.983MW;

Total Power Generation Efficiency:

Calculate the total power generation efficiency η _e1 = 55.81%;

Total heat rate:

Obtain the total heat consumption rate q ₁ =6450.46kJ/KW.h;

② Integrated garbage-gas-steam combined cycle power generation system:

The steam generated by the waste incinerator is heated up to t _hs1 560°C by the superheater of the waste heat boiler. This part of the steam passes through the high-pressure cylinder and then enters the reheater of the waste heat boiler for heating. The heat absorbed by the steam in the waste heat boiler is Q _ws :

Q _ws ＝D _w (h _hs1 -h _ws0 +h _re -h _hs2 )/3.6 (9)

Calculate the water vapor produced by the waste incinerator to absorb heat in the waste heat boiler Q _ws = 8.910MW

From the heat balance, the water entering the waste heat boiler economizer is heated in the waste heat boiler, and the amount of steam generated m _{stream1 is} :

It is obtained that the water entering the waste heat boiler economizer is heated in the waste heat boiler, and the amount of steam generated m _stream1 = 94.27kg/s

Then the steam turbine work P _st :

P _st ＝(m _stream1 +D _w )[(h _hs1 -h _hs2 )+(h _re -h _ls2 )]/1000 (11)

Obtain steam turbine work P _st = 163.528MW;

Assume that the mechanical efficiency η _m of the unit is 0.99, and the generator efficiency η _g is 0.96.

The total output of the integrated overall system:

P _e2 ＝(P _gt +P _st )η _m η _g (12)

The total output P _e2 = 407.986MW;

Total power generation efficiency:

The total power generation efficiency η _e2 = 56.50%;

Total heat rate:

Get the total heat rate q ₂ =6371.5kJ/KW.h;

The following table shows the comparison of the main economic indicators of the discrete system and the overall integrated system. The comparison shows that the total power generation thermal efficiency of the unit has increased by 1.2%, and the total output of the unit has increased by 5.003MW.

Table 3 Comparison of the traditional discrete system and the integrated garbage-gas-steam cycle power generation system as a whole system

The above descriptions are only examples of the preferred implementation of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention within.

Claims (5)

1. An overall combined cycle power generation system integrating garbage-gas-steam, including a garbage incinerator (10), a waste heat boiler (4) and a compressor (1), a combustion chamber (2), and a turbine (3) connected in sequence ), steam turbine and generator (19), characterized in that: The steam at the outlet of the waste incinerator (10) is mixed with the steam at a similar temperature in the waste heat boiler (4) and then enters the third superheater (9) in the high temperature section of the waste heat boiler (4) for heating and superheating, using the high temperature at the outlet of the turbine (3) The flue gas is used as a heat source to heat the mixed steam in the waste heat boiler (4) and enter the steam turbine to do work. The waste steam after work is condensed into water and then enters the waste heat boiler (4) and the waste incineration (10) furnace to form a thermodynamic cycle. 2. The integrated combined cycle power generation system according to claim 1, characterized in that: the steam turbine has a high-pressure cylinder (16), a medium-pressure cylinder (17) and a low-pressure cylinder (18) connected coaxially in sequence. 3. The integrated combined cycle power generation system according to claim 2, characterized in that: the first economizer (11), the first evaporator (12) and the second A superheater (13), part of the condensed water after the steam turbine has done work passes through the first economizer (11), the first evaporator (12) and the first superheater (13) in turn to form the outlet of the waste incinerator (10) steam. 4. The integrated combined cycle power generation system according to claim 3, characterized in that: a second economizer (5), a second evaporator (6), and a second superheater are installed in the waste heat boiler (4) (7), reheater (8) and third superheater (9), wherein the second economizer (5), second evaporator (6) and second superheater (7) are connected in sequence, the first superheater The outlet of the device (13) and the second superheater (7) is respectively connected with the inlet of the third superheater (9) through pipelines, and the outlet of the third superheater (9) is connected with the high-pressure cylinder (16), and the high-pressure cylinder (16 ) is connected to the inlet of the reheater (8), the outlet of the reheater (8) is connected to the inlet of the medium pressure cylinder (17), and the outlet of the medium pressure cylinder (17) passes through the pipeline and the low pressure cylinder (18) import connection; A condenser (15) and a feed water pump (14) are sequentially connected at the outlet of the low-pressure cylinder (18), used to condense exhaust steam after the steam turbine has done work into water and then pump it into the first economizer (5 ) and the second economizer (11). 5. The integrated combined cycle power generation system according to claim 4, characterized in that: said integrated combined cycle power generation system operates in parallel with an external power grid.