CN104595136B - A kind of solar energy auxiliary reheating backheat heat power generating system and emission reduction expansion method - Google Patents

Abstract

The invention discloses a solar energy assisted reheat heat recovery thermal power generation system. Boiler, steam turbine, condenser, main circulation pump, heat recovery heater, and boiler are connected in sequence to form a main circulation loop; the concentrating mirror field focuses sunlight on the solar heat absorber; solar heat absorber, solar high temperature reheater, solar energy The heat recovery reheater, secondary circulation pump, and solar heat absorber are connected in sequence to form a secondary cycle solar heating circuit; the inlet of the low-pressure cylinder of the steam turbine is connected in sequence with the high-temperature solar reheater and the outlet of the high-pressure cylinder of the steam turbine to form a reheat circuit; the low-pressure cylinder of the steam turbine The regenerative steam extraction port is sequentially connected with the solar regenerative reheater and the regenerative heater; the steam turbine is connected with the generator. The present invention utilizes the secondary cycle of solar energy to realize the purpose of reducing coal consumption and increasing the total power of the system by increasing the reheating surface and regenerative reheating. Based on the full use of solar energy, the original system can operate independently, realizing the function of using solar heat storage to meet the peak and valley energy supply of the regulation system.

Description

A solar-assisted reheating heat recovery thermal power generation system and method for reducing emission and expanding capacity

technical field

The invention relates to a thermal power generation system and solar energy technology, in particular to a solar-assisted reheating heat generation system and a method for reducing emission and expanding capacity.

Background technique

In my country's energy structure, thermal power accounts for more than 70% of the installed capacity of electricity, and coal-fired units are the main thermal power generation units. In recent years, coal-fired power plant boilers have developed rapidly in the direction of large capacity and high parameters, and both manufacturing and operation management have approached the advanced level abroad; while coal-fired industrial boilers have a large number of reserves, wide distribution, high energy consumption, heavy pollution, and energy efficiency. Compared with foreign countries, there is a certain gap in the overall level of pollution control, and the potential for energy saving and emission reduction is huge.

Large-scale coal-fired power plants have achieved a certain degree of control over the emission reduction of SO _x , NO _x , dust and other pollutants through desulfurization and denitrification technology. At present, coal-fired power plants across the country emit 1.5 million tons of soot a year, and this figure was about 4 million tons in 1980. Over the past 30 years, the installed capacity of coal-fired power plants in my country has increased more than ten times, but the total amount of smoke and dust emissions has dropped significantly. Sulfur dioxide emissions from electricity dropped from 13 million tons in 2005 to 8.83 million tons in 2012, and nitrogen oxide emissions dropped to over 9 million tons.

However, with the increasing pressure on the environment, the emission reduction reform encountered difficulties again.

First of all, on January 1, 2012, the Ministry of Environmental Protection implemented the latest "Emission Standards of Air Pollutants for Thermal Power Plants". According to regulations, the smoke and dust emission limit is reduced from 50 mg/m3 to 30 mg/m3; from January 1, 2012, the nitrogen oxide emission standard of newly built thermal power units is 100 mg/m3; on July 1, 2014 From now on, the nitrogen oxide emission standard of existing thermal power units is 100 mg/m3. The strictness of this "limited time and limited quantity" environmental protection renovation standard can be called "the most in the world". Strict standards are not matched with reasonable compensation mechanisms. Most of the power companies interviewed said that the state subsidy is lower than the investment in environmental protection, and the enterprise's enthusiasm for transformation has been severely frustrated.

Secondly, at present, the capacity of most coal-fired industrial boilers in my country is relatively small. Equipped with effective dust removal devices, there are basically no desulfurization and denitrification facilities, and the emission exceeds the standard seriously. The pollution emission problem needs to be solved urgently.

Finally, since coal is a full-carbon-based fossil fuel, existing technical ideas still cannot achieve an effective reduction of _CO2 emissions. Even with _CO2 absorption technology, how to deal with the recovered _CO2 is a major challenge.

Based on the above pressures and difficulties, it is imperative to adopt new energy-saving boilers. Replacing the existing low-efficiency boilers with new energy-saving boilers is an effective means to solve the current excessive emissions of SOx, NOx, and CO2.

As a clean and renewable energy source, solar energy plays an important role in reducing pollutant emissions. How to use the system equipment of the existing coal-fired power station, combined with the solar energy technology to realize the pollutant discharge standard of the existing unit and at the same time improve the economy of solar energy utilization is of great significance.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, and provide a solar-assisted reheating heat generation system and a method for reducing emission and expanding capacity.

To achieve the above object, the present invention adopts the following technical solutions:

The solar assisted reheat heat recovery thermal power generation system includes a boiler, a solar high temperature reheater, a steam turbine, a generator, a condenser, a main circulation pump, a solar heat recovery reheater, a heat recovery heater, a solar heat absorber, a condenser field, The secondary circulation pump; the boiler is connected in sequence with the steam turbine, condenser, main circulation pump, recuperation heater, and boiler to form the main circulation loop; the concentrating mirror field focuses the sunlight on the solar heat absorber; Heater, solar heat recovery reheater, secondary circulation pump, and solar heat absorber are connected in sequence to form a secondary cycle solar heating circuit; the inlet of the low-pressure cylinder of the steam turbine is connected in sequence with the high-temperature solar reheater and the outlet of the high-pressure cylinder of the steam turbine to form a reheating circuit ; The steam turbine low-pressure cylinder regenerative steam outlet is connected to the solar regenerative reheater and the regenerative heater in sequence; the steam turbine is connected to the generator.

The solar high-temperature reheater is a high-temperature solar heat storage heat exchanger, the heat storage temperature is 500°C-1300°C, and the heat storage working medium includes high-temperature lava and graphite.

The solar heat recovery reheater is a medium-high temperature solar heat storage heat exchanger, the heat storage temperature is 250°C-500°C, and the heat storage working medium includes high-temperature lava, graphite and heat transfer oil.

The emission reduction and capacity expansion method of the solar assisted reheating thermal power generation system is as follows: on the basis of the existing thermal power generation system, by adding concentrating mirror field, solar heat absorber, solar high temperature reheater, solar energy recuperation reheater, The secondary circulation pump is the solar secondary circulation loop of the main equipment, to achieve the purpose of increasing the reheating surface of the original system and increasing the reheating and reheating process. The reheating surface is increased by the solar high temperature reheater to achieve the effect of increasing the reheating circulation flow of the boiler under the same coal combustion and flow conditions, and using the design margin of the steam turbine to increase the power of the system; at the same time, the boiler flow can also be reduced accordingly and coal consumption, use the solar high temperature reheater to increase the reheating cycle flow to ensure the system power remains unchanged, and the purpose of reducing coal consumption and emissions; the steam turbine low-pressure cylinder is reheated and extracted by the solar reheater to heat the temperature and parameters The steam parameters of the high-pressure cylinder of the steam turbine are the same, on the one hand, the cascade utilization of solar energy is realized, and the working temperature and operation safety of the secondary circulation pump are guaranteed. The purpose of reducing boiler coal consumption, and ultimately achieve the purpose of reducing emissions and increasing efficiency.

The present invention has the beneficial effect compared with prior art:

1) On the basis of the existing thermal cycle, a relatively independent solar secondary cycle is added, and the solar secondary cycle is used to reduce coal consumption and increase the total power of the system by increasing the reheating surface and reheating and reheating;

2) This system has very little changes to the existing power station system. Moreover, the solar secondary cycle can operate independently from the main cycle as an independent unit. Therefore, on the basis of ensuring the full use of solar energy, it also ensures the original system. It can operate independently, and at the same time, it can also realize the function of using solar heat storage to meet the peak and valley energy supply of the regulation system;

3) Through two-stage heat storage, the system realizes the cascade utilization of solar energy and improves the utilization rate of solar energy on the one hand. Moreover, through two-stage heat storage, the inlet temperature of the heat absorber is reduced, ensuring that the secondary circulation pump can Working under relatively low temperature conditions improves the stability and life of the pump and reduces investment costs.

Description of drawings

Figure 1 is a schematic diagram of a solar-assisted reheating heat generation system;

In the figure: boiler 1, solar high temperature reheater 2, steam turbine 3, generator 4, condenser 5, main circulation pump 6, solar recuperator reheater 7, recuperation heater 8, solar heat absorber 9, condenser mirror field 10, secondary circulation pump 11.

detailed description

As shown in Figure 1, the solar assisted reheat heat recovery thermal power generation system includes a boiler 1, a solar high temperature reheater 2, a steam turbine 3, a generator 4, a condenser 5, a main circulation pump 6, a solar heat recovery reheater 7, Regeneration heater 8, solar heat absorber 9, concentrator field 10, secondary circulation pump 11; boiler 1 is connected with steam turbine 3, condenser 5, main circulation pump 6, recovery heater 8, and boiler 1 in order to form the main circulation Loop; Concentrating mirror field 10 focuses sunlight onto the solar heat absorber 9; The connection forms a secondary cycle solar heating circuit; the inlet of the steam turbine 3 low-pressure cylinder is connected with the solar high-temperature reheater 2 and the outlet of the steam turbine 3 high-pressure cylinder in sequence to form a reheat circuit; the steam turbine 3 low-pressure cylinder reheating exhaust port and the solar reheater 7. The regenerative heater 8 is connected in sequence; the steam turbine 3 is connected with the generator 4 .

The solar high-temperature reheater 2 is a high-temperature solar heat storage heat exchanger, the heat storage temperature is 500°C-1300°C, and the heat storage working fluid includes high-temperature lava and graphite.

The solar heat recovery reheater 7 is a medium-high temperature solar heat storage heat exchanger, the heat storage temperature is 250°C-500°C, and the heat storage working medium includes high-temperature lava, graphite and heat transfer oil.

The emission reduction and capacity expansion method of the solar assisted reheating thermal power generation system is: on the basis of the existing thermal power generation system, by adding the concentrating mirror field 10, the solar heat absorber 9, the solar high temperature reheater 2, and the solar heat recovery The heater 7 and the secondary circulation pump 11 are the solar secondary circulation loops of the main equipment to achieve the purpose of increasing the reheating surface of the original system and increasing the reheating and reheating process. The reheating surface is increased through the solar high temperature reheater 2, so as to achieve the effect of increasing the reheating circulation flow rate of the boiler 1 under the same coal combustion and flow rate conditions, and using the design margin of the steam turbine 3 to increase the power of the system; Reduce boiler 1 flow and coal consumption, use solar high-temperature reheater 2 to increase reheating circulation flow, in order to ensure system power remains unchanged, coal consumption and emission reduction; The temperature and parameters of hot extraction steam are heated to be the same as the steam parameters of the steam turbine 3 high-pressure cylinder. On the one hand, the cascade utilization of solar energy is realized, and the working temperature and operation safety of the secondary circulation pump 11 are guaranteed. At the same time, the regeneration heating of the original system is improved. capacity, and ultimately achieve the purpose of improving solar energy utilization and reducing boiler coal consumption, and ultimately achieve the purpose of reducing emissions and increasing efficiency.

The implementation process of the solar assisted reheating heat recovery thermal power generation system is as follows: by installing a concentrating mirror around the existing power station, the reflected light is focused on the solar heat absorber to heat the heat exchange working medium, and the heated heat exchange working medium passes through the The secondary circulation pump flow successively flows into the solar high temperature reheater and the solar regenerative reheater for heating, and finally flows back to the solar heat absorber to form the secondary circulation solar heating circuit. The solar high-temperature reheater realizes solar reheating by heating the steam at the outlet of the high-pressure cylinder of the steam turbine and then entering the inlet of the low-pressure cylinder. The solar recuperation reheater heats the low-pressure cylinder reheating exhaust steam and then flows into the regenerating heater to heat the boiler to make up water.

When the coal consumption of the boiler is reduced, that is, the heat generated by the boiler combustion is reduced. Therefore, it is necessary to reduce the boiler circulation flow accordingly to ensure the pressure and parameters of the steam at the boiler outlet. The amount of hot extraction steam can increase the reheat cycle ratio to ensure that the power of the steam turbine does not decrease, so as to achieve the purpose of reducing coal consumption and emissions.

When the coal consumption remains unchanged, since the solar high-temperature reheater provides more heat exchange surface and heat exchange capacity, considering that the existing steam turbine unit has a large margin in design, it can be improved by increasing the reheater Heat cycle flow to achieve the purpose of increasing steam turbine power.

Moreover, the solar heat recovery reheater increases the steam parameters of the low-pressure cylinder of the steam turbine by heating, on the one hand, it ensures the temperature of the solar cycle inlet, on the other hand, it increases the reheat temperature, thereby increasing the boiler inlet temperature, and also leads to the reduction of boiler coal consumption , to achieve the purpose of emission reduction.

Moreover, during the entire implementation process, the main cycle of the boiler system can operate independently of the secondary cycle of solar energy, which also ensures that the boiler system can operate normally and stably when solar energy is insufficient. In addition, the continuous operation of the solar system and the flexible arrangement of the solar energy utilization period are also guaranteed through the heat storage method, so as to achieve the peak and valley balance of the entire system.

In the present invention, the solar heat storage heat exchanger is used as a reheater to increase the reheating surface of the existing thermal power generation system, and the regenerative reheater is used to increase the reheating temperature of the system, so as to realize partial function substitution of solar energy for coal burning, and achieve emission reduction and The purpose of capacity expansion is to achieve the purpose of economical utilization of solar energy and emission reduction of existing power stations.

Claims (4)

1. a kind of solar energy aids in reheating backheat heat power generating system, it is characterised in that including boiler（1）, solar energy high temperature reheating Device（2）, steam turbine（3）, generator（4）, condenser（5）, main circulation pump（6）, solar energy backheat reheater（7）, backheat heating Device（8）, solar heat absorber（9）, condenser（10）, secondary circulating pump（11）；Boiler（1）With steam turbine（3）, condenser（5）、 Main circulation pump（6）, bleeder heater（8）It is sequentially connected with composition main circulation loop；Condenser（10）By solar light focusing to too Positive energy heat dump（9）On；Solar heat absorber（9）, solar energy high temperature reheater（2）, solar energy backheat reheater（7）, secondary follow Ring pump（11）It is sequentially connected with composition time circulating solar energy heating circuit；Steam turbine（3）Low pressure (LP) cylinder entrance and solar energy high temperature reheating Device（2）, steam turbine（3）High pressure cylinder outlet is sequentially connected with composition reheat loop；Steam turbine（3）Low pressure (LP) cylinder regenerative steam mouthful and the sun Can backheat reheater（7）, bleeder heater（8）It is sequentially connected with；Steam turbine（3）With generator（4）Connection.

2. solar energy according to claim 1 aids in reheating backheat heat power generating system, it is characterised in that the described sun Can high temperature reheater（2）For high temperature solar regenerative heat exchanger, regenerator temperature is 500 DEG C ~ 1300 DEG C, and accumulation of heat working medium includes high temperature Lava and graphite.

3. solar energy according to claim 1 aids in reheating backheat heat power generating system, it is characterised in that the described sun Can backheat reheater（7）For high temperature solar heat-preservation heat exchanger, regenerator temperature is 250 DEG C ~ 500 DEG C, and accumulation of heat working medium includes height Warm lava, graphite and conduction oil.

4. solar energy according to claim 1 aids in the emission reduction expansion method of reheating backheat heat power generating system, its feature It is：On the basis of existing heat power generating system, by increasing with condenser（10）, solar heat absorber（9）, solar energy High temperature reheater（2）, solar energy backheat reheater（7）, secondary circulating pump（11）For the solar energy time circulation loop of capital equipment, reach To increase original system reheating face and the purpose of increase backheat thermal process again, pass through solar energy high temperature reheater（2）Increase reheating Face, to reach boiler（1）Under identical coal-fired and flow condition, increase reheat vapor cycle flow, utilize steam turbine（3）Design more than Measure the effect of the power of raising system；Simultaneously also can be by accordingly reducing boiler（1）Flow and Coal-fired capacity are high using solar energy Warm reheater（2）Increase reheat vapor cycle flow, to ensure that system power is constant, the purpose of coal consumption and discharge reduction；Pass through the sun Can backheat reheater（7）By steam turbine（3）Low pressure (LP) cylinder regenerative steam temperature and parameter are heated to and steam turbine（3）High pressure cylinder steam Parameter is identical, on the one hand realizes the cascade utilization of solar energy, it is ensured that secondary circulating pump（11）Operating temperature and operation safety, Meanwhile, the backheat heating efficiency of original system is improved, the mesh for improving solar energy utilization ratio and reducing boiler coal consumption is finally reached , it is finally reached the purpose of emission reduction synergy.