CN216198464U

CN216198464U - Fused salt and steam combined cycle power generation system of internal combustion engine

Info

Publication number: CN216198464U
Application number: CN202122380433.2U
Authority: CN
Inventors: 崔华; 金红光; 王永生
Original assignee: Hepp Energy Environment Technology Co ltd; Institute of Engineering Thermophysics of CAS
Current assignee: Hepp Energy Environment Technology Co ltd; Institute of Engineering Thermophysics of CAS
Priority date: 2021-02-26
Filing date: 2021-09-29
Publication date: 2022-04-05
Anticipated expiration: 2031-09-29
Also published as: CN114961986A

Abstract

The utility model discloses a fused salt and steam combined cycle power generation system of an internal combustion engine, which comprises: the internal combustion engine (1) drives the first generator (13) to generate electricity, the steam turbine (9) drives the second generator (15) to generate electricity, and an inlet and an outlet of the steam turbine (9) are communicated through a steam pipeline; the steam pipeline enters the steam-molten salt heat exchanger (5) to exchange heat with high-temperature molten salt in the molten salt pipeline, so that low-pressure saturated steam in the steam pipeline is heated into superheated steam and then conveyed to the steam turbine (9). The utility model utilizes high-temperature molten salt to heat steam in a gradient manner, ensures that the temperature of main steam does not rise rapidly to a large extent while the load of the internal combustion engine (1) is increased rapidly, and ensures that the temperature of main steam does not drop rapidly to a large extent while the load of the internal combustion engine (1) is reduced rapidly, thereby improving the main steam parameters and the thermal efficiency of the steam turbine (9), obviously improving the power generation efficiency of the internal combustion engine combined cycle, and obviously improving the peak-load and frequency modulation capability.

Description

Fused salt and steam combined cycle power generation system of internal combustion engine

Technical Field

The utility model relates to the technical field of internal combustion engines, in particular to a fused salt and steam combined cycle power generation system of an internal combustion engine.

Background

Under the influence of industrial structure adjustment and urbanization, the power consumption peak-valley difference in China is continuously increased, and the peak regulation pressure of a power system is further increased due to the increase of new energy installation machines such as wind power and photovoltaic, so that the demand of the power system on a flexible power supply is increasingly increased. Compared with a gas turbine, the gas internal combustion engine is a mature power generation technical route, has the advantages of higher start-stop speed (the start speed is 1-2 minutes, the gas turbine is 20-30 minutes), better frequency modulation and peak regulation capacity (the frequency modulation capacity reaches 30-80% of rated power/minute, the gas turbine is 4-8% of rated power/minute), stronger fuel compatibility (can be compatible with methane and a certain proportion of hydrogen), and can play an important role in the flexibility of a future power system. Moreover, the internal combustion engine has more selectable models and no requirement on the gas pressure, and can be directly connected to a municipal gas pipe network, so that the internal combustion engine is also suitable for distributed power generation and is arranged on user sides such as an industrial park.

However, the power generation efficiency of the internal combustion engine is lower than that of the gas turbine. In the combined cycle mode, the power generation efficiency of the internal combustion engine is only about 50%, and the power generation efficiency of the gas turbine can reach 55% -60%. The main reason is that the exhaust temperature of the internal combustion engine is only 350-. Because the exhaust gas temperature is low, the main steam parameters which can be generated by the waste heat boiler are low, and the efficiency of the steam turbine is lower than 30%. Meanwhile, in the combined cycle mode, the excellent frequency modulation capability of the internal combustion engine cannot be fully exerted due to the limitation of the load regulation capability of the steam turbine.

In the prior art, the flue gas is used for refrigerating or heating by converting high-temperature flue gas into cold energy by using an absorption refrigerator, or directly using the high-temperature flue gas for heating. However, since the cold load and the heat load do not exist all year round and are not consistent with the characteristics of the electric load, the system is not efficient in energy utilization when the cold load and the heat load are lacked.

The waste heat boiler and the steam turbine are added to realize combined cycle power generation, and the heat of the flue gas is used for generating steam, so that the steam turbine is pushed to generate power. However, because the temperature of the flue gas of the internal combustion engine is lower (obviously lower than that of the flue gas of the gas turbine), generally between 350 ℃ and 400 ℃, the main steam parameters which can be generated by the waste heat boiler are lower, only about 330 ℃, the efficiency of the gas turbine is lower than 30%, and the loss of the cold source accounts for a larger amount. Meanwhile, in order to avoid thermal stress damage, the temperature difference between main steam and parts of the steam turbine is not too high, so that the power regulation speed of the steam turbine is obviously slower than that of an internal combustion engine. In the combined cycle mode, the frequency modulation capability of the whole system is greatly influenced, and the excellent frequency modulation capability of the internal combustion engine cannot be fully exerted.

SUMMERY OF THE UTILITY MODEL

Objects of the utility model

The utility model aims to provide a fused salt and steam combined cycle power generation system of an internal combustion engine, which solves the problem of low combined cycle power generation efficiency of the internal combustion engine and improves the peak regulation and frequency modulation capability of the combined cycle power generation system of the internal combustion engine.

(II) technical scheme

To solve the above problems, according to an aspect of the present invention, there is provided an internal combustion engine molten salt steam combined cycle power generation system including: the internal combustion engine drives the first generator to generate electricity; the steam turbine drives the second generator to generate electricity; two ports of the steam pipeline are respectively communicated with an inlet and an outlet of the steam turbine; and the steam pipeline enters the steam-molten salt heat exchanger to exchange heat with the molten salt pipeline in the steam-molten salt heat exchanger so as to heat the low-pressure saturated steam in the steam pipeline into superheated steam and convey the superheated steam to the steam turbine.

Further, the method also comprises the following steps: the system comprises a low-temperature molten salt storage tank for storing low-temperature liquid molten salt and a high-temperature liquid molten salt storage tank for storing high-temperature molten salt; the outlet of the low-temperature molten salt storage tank is communicated with the inlet of the high-temperature molten salt storage tank through the molten salt pipeline, and the inlet of the low-temperature molten salt storage tank is communicated with the outlet of the high-temperature molten salt storage tank through the molten salt pipeline; a molten salt electric heater is arranged on the molten salt pipeline between the outlet of the low-temperature molten salt storage tank and the inlet of the high-temperature molten salt storage tank, the low-temperature liquid molten salt output from the outlet of the low-temperature molten salt storage tank is heated into high-temperature liquid molten salt, and the high-temperature liquid molten salt is stored in the high-temperature molten salt storage tank; and the molten salt pipeline between the inlet of the low-temperature molten salt storage tank and the outlet of the high-temperature molten salt storage tank enters the steam-molten salt heat exchanger, and the heat of the high-temperature liquid molten salt is transferred to the steam pipeline.

Further, the method also comprises the following steps: a molten salt circulating pump; the molten salt circulating pump is arranged at an outlet of the low-temperature molten salt storage tank so as to adjust the flow speed of the output low-temperature liquid molten salt; and/or the molten salt circulating pump is arranged at the outlet of the high-temperature molten salt storage tank so as to adjust the flow speed of the output high-temperature liquid molten salt.

Further, the method also comprises the following steps: an evaporator; the steam pipeline sequentially enters the evaporator, the steam-molten salt heat exchanger and the steam turbine; and a flue gas pipeline of the internal combustion engine enters the evaporator, low-pressure saturated steam in the steam pipeline exchanges heat with high-temperature flue gas in the flue gas pipeline to form superheated steam, and the superheated steam enters the steam-molten salt heat exchanger and then exchanges heat with high-temperature liquid molten salt in the molten salt pipeline for the second time.

Further, the method also comprises the following steps: an evaporator; the steam pipeline sequentially enters one side of the evaporator, the steam-molten salt heat exchanger and the steam turbine, and the molten salt pipeline sequentially enters the other side of the steam-molten salt heat exchanger and the evaporator; and the low-pressure saturated steam in the steam pipeline exchanges heat with the medium-temperature liquid molten salt in the molten salt pipeline in the evaporator for the first time to form superheated steam, and the superheated steam enters the steam-molten salt heat exchanger and then exchanges heat with the high-temperature liquid molten salt in the molten salt pipeline for the second time.

Further, the method also comprises the following steps: a low temperature flue gas heat exchanger; the steam pipeline sequentially penetrates through the low-temperature flue gas heat exchanger and one side of the evaporator, and the flue gas pipeline of the internal combustion engine sequentially penetrates through the evaporator and the other side of the low-temperature flue gas heat exchanger, so that high-temperature flue gas in the flue gas pipeline exchanges heat for the steam pipeline.

Further, the method also comprises the following steps: a condenser; the condenser is arranged at an outlet of the steam turbine, and the steam pipeline enters the condenser to condense low-pressure saturated steam discharged from the outlet of the steam turbine into water.

Further, the method also comprises the following steps: a water heat exchanger; a water pipeline of the internal combustion engine is communicated with the internal combustion engine and the water heat exchanger in a circulating mode; the steam pipeline sequentially enters the condenser and the water heat exchanger; and low-pressure saturated steam in the steam pipeline is condensed into water in the condenser, and the water enters the water heat exchanger and exchanges heat with cylinder sleeve water in the water pipeline.

Further, the method also comprises the following steps: a deaerator; the deaerator is arranged at the outlet of the water heat exchanger, the steam pipeline for heat exchange in the water heat exchanger enters the deaerator, and the deaerator removes dissolved oxygen and other gases in water.

Further, the low-temperature liquid molten salt is nitrate, and the storage temperature is 280 ℃; the high-temperature liquid molten salt is nitrate, and the storage temperature is 565 ℃.

(III) advantageous effects

The technical scheme of the utility model has the following beneficial technical effects:

(1) in the low ebb period of electricity consumption, the molten salt is heated by using ebb electricity or surplus renewable energy; and in the peak period of power utilization, the internal combustion engine cycle power generation system is started, and the cylinder sleeve water, the flue gas and the high-temperature molten salt of the internal combustion engine are utilized to carry out step heating on the condensed water, the feed water and the steam, so that the main steam parameters and the heat efficiency of the steam turbine are improved. The quick response capability of the fused salt-steam heat exchanger is utilized, the heat exchange quantity is adjusted according to the load change of the internal combustion engine, the steam parameter change and the influence on a steam turbine caused by the quick change of the smoke of the internal combustion engine are relieved, the frequency modulation capability of a system is improved, and the power generation efficiency of the internal combustion engine combined cycle is improved.

(2) According to the technical scheme of heating the water supply by the molten salt and the flue gas in a stepped manner, the exhaust temperature of the internal combustion engine is between 300 ℃ and 400 ℃, and the working temperature of the molten salt is between 290 ℃ and 580 ℃, so that the two have complementarity, and the continuous heating of the water supply can be realized. The high-temperature molten salt is used for heating the steam, the efficiency of the steam turbine is improved, and the combined cycle efficiency of the internal combustion engine can be improved to about 55% from 50% of the traditional combined cycle technology.

(3) Meanwhile, the utility model can dynamically adjust the heat exchange quantity of the fused salt and the steam, and the limitation of the adjusting speed of the steam turbine on the adjusting speed in the whole system is removed by utilizing the dynamic adjustment of the fused salt and the steam heat exchange, and the frequency modulation performance is far better than that of the traditional combined cycle technology.

(4) The utility model optimizes the arrangement of the heat exchanger, the evaporator and the steam-molten salt heat exchanger, and realizes higher-level utilization of the waste heat of the flue gas of the internal combustion engine and the waste heat of the water in the cylinder sleeve.

(5) The utility model adds the molten salt heat storage, stores the surplus power of the system in a high-temperature molten salt form, and solves the problem of surplus power. The peak regulation capability is better.

Drawings

FIG. 1 is a schematic diagram of a molten salt steam combined cycle power generation system of an internal combustion engine according to an embodiment of the utility model;

FIG. 2 is a schematic diagram of a molten salt and steam combined cycle power generation system of an internal combustion engine according to an embodiment of the utility model.

Reference numerals:

1-an internal combustion engine; 2-low temperature flue gas heat exchanger; 3-an evaporator; 4-a water heat exchanger; 5-steam-molten salt heat exchanger; 6-low temperature molten salt storage tank; 7-high temperature molten salt storage tank; 8-molten salt circulating pump; 9-a steam turbine; 10-a molten salt electric heater; 11-a condenser; 12-a deaerator; 13-a first generator; 14-a chimney; 15-second generator.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings in conjunction with the following detailed description. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.

The present invention will be described in detail below with reference to the accompanying drawings and examples.

The first embodiment is as follows:

fig. 1 is a schematic diagram of a molten salt and steam combined cycle power generation system of an internal combustion engine according to an embodiment of the present invention, and please refer to fig. 1.

In a first embodiment, the utility model provides a fused salt and steam combined cycle power generation system of an internal combustion engine, which comprises the following equipment: the system comprises an internal combustion engine 1, a low-temperature flue gas heat exchanger 2, an evaporator 3, a water heat exchanger 4, a steam-molten salt heat exchanger 5, a low-temperature molten salt storage tank 6, a high-temperature molten salt storage tank 7, a molten salt circulating pump 8, a steam turbine 9, a molten salt electric heater 10, a condenser 11, a deaerator 12, a first generator 13, a chimney 14 and a second generator 15.

The internal combustion engine 1 can convert chemical energy into mechanical energy and drive the first generator 13 to generate electricity; the steam turbine 9 is a rotary steam power device, and can convert steam into mechanical energy to drive the second generator 15 to generate electricity. The power regulation speed of the steam turbine 9 is significantly slower than that of the internal combustion engine 1, and the frequency modulation capability of the whole power generation system is greatly influenced in the combined cycle mode, so that the excellent frequency modulation capability of the internal combustion engine 1 cannot be fully exerted.

On the basis, the steam-molten salt heat exchanger 5 is additionally arranged, high-temperature molten salt is used for exchanging heat for steam, low-pressure saturated steam is heated into superheated steam, and the superheated steam is sent to the steam turbine 9 for power generation, so that the power regulation speed of the steam turbine 9 is increased. Specifically, two ports of the steam pipeline are respectively communicated with an inlet and an outlet of the steam turbine 9, the steam pipeline enters the steam-molten salt heat exchanger 5 and exchanges heat with the molten salt pipeline in the steam-molten salt heat exchanger 5, and low-pressure saturated steam in the steam pipeline is heated into superheated steam and conveyed to the steam turbine 9.

In this embodiment, the low-temperature molten salt storage tank 6 is used for storing low-temperature liquid molten salt, the low-temperature liquid molten salt is generally nitrate, and the storage temperature is 280 ℃. The high-temperature liquid molten salt storage tank 7 is used for storing high-temperature liquid molten salt, the high-temperature liquid molten salt is generally nitrate, and the storage temperature is 565 ℃.

An outlet of the low-temperature molten salt storage tank 6 is communicated with an inlet of the high-temperature molten salt storage tank 7 through a molten salt pipeline, and an inlet of the low-temperature molten salt storage tank 6 is communicated with an outlet of the high-temperature molten salt storage tank 7 through a molten salt pipeline; the molten salt pipeline between the outlet of the low-temperature molten salt storage tank 6 and the inlet of the high-temperature molten salt storage tank 7 is provided with a molten salt electric heater 10, and the molten salt electric heater 10 heats the low-temperature liquid molten salt output from the outlet of the molten salt storage tank 6 by using electric energy to obtain high-temperature liquid molten salt and sends the high-temperature liquid molten salt into the high-temperature molten salt storage tank 7 for storage.

And a molten salt pipeline between the inlet of the low-temperature molten salt storage tank 6 and the outlet of the high-temperature molten salt storage tank 7 enters the steam-molten salt heat exchanger 5, so that the molten salt pipeline exchanges heat with the steam pipeline, and the heat of the high-temperature liquid molten salt output from the high-temperature molten salt storage tank 7 in the molten salt pipeline is transferred to low-pressure saturated steam in the steam pipeline.

In this embodiment, the outlet of the low-temperature molten salt storage tank 6 is further provided with a molten salt circulating pump 8, and the molten salt circulating pump 8 can adjust the flow speed of the low-temperature liquid molten salt output by the low-temperature molten salt storage tank 6 as required, so as to control the temperature and the heat absorption capacity of the low-temperature liquid molten salt.

Optionally, the outlet of the high-temperature molten salt storage tank 7 is also provided with a molten salt circulating pump 8, and the molten salt circulating pump 8 can adjust the flow speed of the high-temperature liquid molten salt output by the high-temperature molten salt storage tank 7 as required, so as to control the temperature and the heat release of the high-temperature liquid molten salt.

In this embodiment, the steam pipeline output from the outlet of the steam turbine 9 sequentially enters the evaporator 3 and the steam-molten salt heat exchanger 5, and finally enters the steam turbine 9 through the inlet of the steam turbine 9. Therefore, the low-pressure saturated steam in the steam pipeline firstly enters the evaporator 3 for primary heat exchange and then enters the steam-molten salt heat exchanger 5 for secondary heat exchange.

Specifically, a flue gas pipeline of the internal combustion engine 1 enters the evaporator 3, so that high-temperature flue gas in the flue gas pipeline exchanges heat with low-pressure saturated steam in a steam pipeline, and the flue gas cooled after heat exchange is discharged to the atmospheric environment through a chimney 14; the low-pressure saturated steam after heat exchange forms superheated steam, then enters the steam-molten salt heat exchanger 5 through the steam pipeline, and carries out secondary heat exchange with high-temperature liquid molten salt in the molten salt pipeline, and the superheated steam after secondary heat exchange finally enters the steam turbine 9 for use.

In this embodiment, the low-temperature flue gas heat exchanger 2 is disposed between the evaporator 3 and the chimney 14, the steam pipeline output from the outlet of the steam turbine 9 sequentially passes through the low-temperature flue gas heat exchanger 2 and one side of the evaporator 3, and the flue gas pipeline of the internal combustion engine 1 sequentially passes through the evaporator 3 and the other side of the low-temperature flue gas heat exchanger 2, so that the high-temperature flue gas in the flue gas pipeline exchanges heat to the steam pipeline.

Specifically, high-temperature flue gas in a flue gas pipeline of the internal combustion engine 1 firstly enters the evaporator 3 for heat exchange to obtain medium-temperature flue gas, the medium-temperature flue gas enters the low-temperature flue gas heat exchanger 2 for heat exchange to obtain low-temperature flue gas, and the low-temperature flue gas is discharged through the chimney 14. A steam pipeline output from the outlet of the steam turbine 9 firstly enters the low-temperature flue gas heat exchanger 2 to exchange heat with medium-temperature flue gas in the low-temperature flue gas heat exchanger 2 for the first time, then enters the evaporator 3 to exchange heat with high-temperature flue gas for the second time, and finally enters the steam-molten salt heat exchanger 5 to exchange heat with high-temperature liquid molten salt for the third time.

In the present embodiment, a condenser 11 is provided at the outlet of the turbine 9, and a steam pipe enters the condenser 11 to condense low-pressure saturated steam discharged from the outlet of the turbine 9 into water. The water pipeline of the internal combustion engine 1 is circularly communicated with the internal combustion engine 1 and the water heat exchanger 4, the steam pipeline sequentially enters the condenser 11 and the water heat exchanger 4, low-pressure saturated steam in the steam pipeline is condensed into water in the condenser 11, and the water enters the water heat exchanger 4 to exchange heat with cylinder sleeve water in the water pipeline.

The oxygen-eliminating device 12 is arranged at the outlet of the water heat exchanger 4, a steam pipeline for completing heat exchange in the water heat exchanger 4 enters the oxygen-eliminating device 12, and the oxygen-eliminating device 12 removes dissolved oxygen and other gases in water to prevent the thermal equipment from being corroded.

Optionally, in this embodiment, a liquid molten salt is used as a heat storage medium, but this embodiment is not limited thereto, and the heat storage medium further includes: volcanic rock, magnesia brick, silicone oil, concrete, etc.

Alternatively, the present embodiment is applicable to a single internal combustion engine 1 and a plurality of internal combustion engine 1 modes.

Optionally, the liquid molten salt can be directly heated by non-electric renewable energy sources such as photo-thermal energy, methane and the like.

The operation principle of the first embodiment is as follows:

the internal combustion engine 1 generates electricity, and starts the internal combustion engine 1 to generate electricity and discharges flue gas with the temperature of 350-400 ℃ in the peak period of electricity utilization.

The water heat exchanger 4 works to heat the condensed water output by the condenser 11; specifically, the water heat exchanger 4 heats the condensed water by using the high-temperature cylinder liner water of the internal combustion engine 1, and the heated condensed water enters the deaerator 12. The deoxidized condensed water enters a low-temperature flue gas heat exchanger 2 to be further heated through medium-temperature flue gas, the heated condensed water is input into an evaporator 3, the evaporator 3 utilizes the medium-temperature flue gas of the internal combustion engine 1 to generate low-pressure saturated steam, the low-pressure saturated steam enters a steam-molten salt heat exchanger 5, the low-pressure saturated steam is heated to superheated steam by utilizing high-temperature liquid molten salt, and finally the superheated steam is sent into a steam turbine 9 to drive the steam turbine 9 to generate electricity.

The embodiment utilizes high-temperature flue gas to generate low-pressure saturated steam. The power generation efficiency of generating low-pressure saturated steam by using high-temperature flue gas is higher, while the power generation efficiency of generating low-pressure saturated steam by using liquid molten salt is reduced, but the installed capacity of the steam turbine 9 can be larger.

In the electricity consumption valley period or the renewable energy electricity surplus period, surplus electric energy or solar energy is used for heating the low-temperature liquid molten salt and sending the low-temperature liquid molten salt into the high-temperature liquid molten salt storage tank 7.

The system peak regulation operation mode of the embodiment is as follows: according to the power demand, the starting number of the internal combustion engine 1 is determined, the internal combustion engine 1 is ensured to operate in a full load or high load state, and high energy efficiency is ensured. In the electricity consumption valley period, the internal combustion engine 1 is completely stopped, and the molten salt electric heater 10 heats the molten salt by electricity.

The system frequency modulation operation mode of the embodiment: because the load regulation speed of the steam turbine 9 is far lower than that of the internal combustion engine 1, the dynamic regulation capacity of the fused salt-steam heat exchanger 5 is exerted, and when the load of the internal combustion engine 1 is rapidly increased, the gas flow is increased, the flue gas temperature is increased, and the steam temperature generated by the evaporator 3 is increased. Adjust fused salt circulating pump 8 this moment, reduce the liquid fused salt velocity of flow of high temperature, reduce the heat transfer volume of the liquid fused salt of high temperature and steam, guarantee that main steam temperature does not take place quick rise by a wide margin, avoid the thermal stress damage of steam turbine 9. So that the frequency modulation capability of the internal combustion engine 1 is fully exerted. When the load of the internal combustion engine 1 is rapidly reduced, the gas flow is reduced, the flue gas temperature is reduced, and the steam temperature generated by the evaporator 3 is reduced. At the moment, the flow speed of the high-temperature liquid fused salt is improved, the heat exchange quantity of the high-temperature liquid fused salt and the steam is increased, the temperature of the main steam is guaranteed not to drop rapidly by a large margin, and the thermal stress damage of the steam turbine 9 is avoided. So that the frequency modulation capability of the internal combustion engine 1 is fully exerted.

Example two:

fig. 2 is a schematic diagram of a molten salt and steam combined cycle power generation system of an internal combustion engine according to a second embodiment of the present invention, please see fig. 2.

In an embodiment, the utility model provides a molten salt and steam combined cycle power generation system of an internal combustion engine, comprising the following devices: the system comprises an internal combustion engine 1, a low-temperature flue gas heat exchanger 2, an evaporator 3, a water heat exchanger 4, a steam-molten salt heat exchanger 5, a low-temperature molten salt storage tank 6, a high-temperature molten salt storage tank 7, a molten salt circulating pump 8, a steam turbine 9, a molten salt electric heater 10, a condenser 11, a deaerator 12, a first generator 13, a chimney 14 and a second generator 15.

In the embodiment, a steam pipeline output from an outlet of the steam turbine 9 sequentially enters the evaporator 3 and one side of the steam-molten salt heat exchanger 5, and finally enters the steam turbine 9 through an inlet of the steam turbine 9; the molten salt pipeline sequentially enters the steam-molten salt heat exchanger 5 and the other side of the evaporator 3; the low-pressure saturated steam in the steam pipeline firstly enters the evaporator 3 for primary heat exchange and then enters the steam-molten salt heat exchanger 5 for secondary heat exchange.

Specifically, the low-pressure saturated steam in the steam pipeline forms superheated steam after primary heat exchange with the medium-temperature liquid molten salt in the molten salt pipeline in the evaporator 3, the superheated steam enters the steam-molten salt heat exchanger 5 and then carries out secondary heat exchange with the high-temperature liquid molten salt in the molten salt pipeline, and the superheated steam after the secondary heat exchange finally enters the steam turbine 9 for use.

In the embodiment, the low-temperature flue gas heat exchanger 2 is arranged between the internal combustion engine 1 and the chimney 14, a steam pipeline output from the outlet of the steam turbine 9 sequentially passes through the low-temperature flue gas heat exchanger 2, the evaporator 3 and one side of the steam-molten salt heat exchanger 5, and a flue gas pipeline of the internal combustion engine 1 passes through the other side of the low-temperature flue gas heat exchanger 2. High-temperature flue gas in a flue gas pipeline of the internal combustion engine 1 enters the low-temperature flue gas heat exchanger 2 to exchange heat with low-pressure saturated steam in a steam pipeline, and low-temperature flue gas obtained after heat exchange is discharged through a chimney 14. Therefore, a steam pipeline output from the outlet of the steam turbine 9 firstly enters the low-temperature flue gas heat exchanger 2 to exchange heat with high-temperature flue gas in the flue gas pipeline for the first time, and then enters the evaporator 3 to exchange heat with medium-temperature liquid molten salt in the evaporator 3 for the second time; the low-pressure saturated steam after heat exchange forms superheated steam, then enters the steam-molten salt heat exchanger 5 through the steam pipeline, and carries out tertiary heat exchange with high-temperature liquid molten salt in the molten salt pipeline.

The operation principle of the second embodiment is as follows:

The water heat exchanger 4 works to heat the condensed water output by the condenser 11; specifically, the water heat exchanger 4 heats the condensed water by using the high-temperature cylinder liner water of the internal combustion engine 1, and the heated condensed water enters the deaerator 12. The deoxidized condensed water enters a low-temperature flue gas heat exchanger 2 to be further heated through high-temperature flue gas, the heated condensed water is input into an evaporator 3, the evaporator 3 utilizes medium-temperature liquid molten salt to generate low-pressure saturated steam and sends the low-pressure saturated steam into a steam-molten salt heat exchanger 5, the steam-molten salt heat exchanger 5 utilizes the high-temperature liquid molten salt to heat the low-pressure saturated steam to superheated steam, and finally the superheated steam is sent into a steam turbine 9 to drive the steam turbine 9 to generate electricity.

The embodiment utilizes liquid molten salt to generate low-pressure saturated steam. The power generation efficiency of generating low-pressure saturated steam by using high-temperature flue gas is higher, while the power generation efficiency of generating low-pressure saturated steam by using liquid molten salt is reduced, but the installed capacity of the steam turbine 9 can be larger.

The system frequency modulation operation mode of the embodiment: because the load regulation speed of the steam turbine 9 is far lower than that of the internal combustion engine 1, the dynamic regulation capacity of the fused salt-steam heat exchanger 5 is exerted, when the load of the internal combustion engine 1 is increased rapidly, the gas flow is increased, the flue gas temperature is increased, the heat exchange quantity of condensed water entering the low-temperature flue gas heat exchanger 2 and high-temperature flue gas is increased, and the steam temperature generated by the evaporator 3 is increased. Adjust fused salt circulating pump 8 this moment, reduce the liquid fused salt velocity of flow of high temperature, reduce the heat transfer volume of the liquid fused salt of high temperature and steam, guarantee that main steam temperature does not take place quick rise by a wide margin, avoid the thermal stress damage of steam turbine 9. So that the frequency modulation capability of the internal combustion engine 1 is fully exerted. When the load of the internal combustion engine 1 is rapidly reduced, the gas flow is reduced, the temperature of the flue gas is reduced, the heat exchange quantity of the condensed water entering the low-temperature flue gas heat exchanger 2 and the high-temperature flue gas is reduced, and the temperature of the steam generated by the evaporator 3 is reduced. At the moment, the flow speed of the high-temperature liquid fused salt is improved, the heat exchange quantity of the high-temperature liquid fused salt and the steam is increased, the temperature of the main steam is guaranteed not to drop rapidly by a large margin, and the thermal stress damage of the steam turbine 9 is avoided. So that the frequency modulation capability of the internal combustion engine 1 is fully exerted.

Example three:

the embodiment provides main specific equipment of a fused salt and steam combined cycle power generation system of an internal combustion engine, which comprises: four 18MW internal combustion engines 1, single cycle efficiency 46% (combined cycle efficiency 50%), exhaust gas temperature 380 ℃, and single unit exhaust gas flow rate about 30 kg/s. The 140MWhth fused salt heat storage device (the low-temperature fused salt storage tank 6 and the high-temperature liquid fused salt storage tank 7) comprises 290 ℃ of low-temperature liquid fused salt, 570 ℃ of high-temperature liquid fused salt and 1500 tons of fused salt in total weight. The steam turbine 9 has main steam flow of 30t/h, main steam parameters of 540 ℃,9MPa and thermal efficiency of 40% under pure condensing conditions. A synchronous generator with the power generation of 20 MW. A 20MW molten salt electric heater 10.

The operation mode of the internal combustion engine molten salt steam combined cycle power generation system of the embodiment is as follows:

and stopping the internal combustion engine 1 and the steam turbine 9 at the electricity consumption valley or the surplus time of renewable energy, heating the liquid molten salt by using the molten salt electric heater 10, and storing the liquid molten salt, wherein the system is in an energy storage state, and the electricity consumption power is 20 MW.

In the peak of electricity consumption or the period of renewable energy source undergeneration, the internal combustion engine 1 and the steam turbine 9 are started, the high-temperature cylinder sleeve water and the flue gas of the internal combustion engine 1 respectively heat and evaporate the condensed water and the feed water, the heat exchange power is 36MW, the steam parameters are 260 ℃, 4Mpa, and the enthalpy value is 2837 kJ/kg.

And then heating the steam by using high-temperature liquid molten salt, raising the temperature, wherein the heat exchange power is 9MW, generating superheated steam with the temperature of 540 ℃ and the temperature of 9MP, driving a steam turbine 9 to generate power, and the enthalpy value of the main steam is 3487 kJ/kg.

Under the full load state, the power of four internal combustion engine 1 generator sets is 72MW, the power of one steam turbine 9 generator set is 20MW, and the total power generation power of the system reaches 92 MW.

The efficiency of the internal combustion engine molten salt steam combined cycle power generation system of the present embodiment is calculated as follows:

the primary energy input includes: natural gas and primary electricity.

Input natural gas heat Q₁156.5 MW;

the input heat of the fused salt and the steam is 8.6MW, the heat source of the fused salt is considered as primary power, about 95 percent of heat storage and heat exchange efficiency is considered, and the input heat corresponds to the primary power Q₂And 9 MW.

The single-cycle power generation efficiency of the internal combustion engine 1 is 46%, and the generated power P1 is 72 MW.

The generating efficiency of the turbine 9 unit is 40%, and the generating power is P2 and 19 MW.

Generating efficiency: η ═ P1+ P2)/(Q1+ Q2 ═ 19+72)/(156.5+9 ═ 55%.

It can be seen that the power generation efficiency of the present embodiment is 9 percentage points higher than that of a single cycle and 5 percentage points higher than that of a conventional combined cycle of the internal combustion engine.

If the waste heat of the cylinder sleeve water is further considered for heat supply, an extraction steam turbine set is adopted. Under the full load heat supply state, the power generation power of the steam turbine unit is 14MW when P3 is 14MW, the heat supply capacity H1 is 20MW, the cylinder liner water heat supply H2 is 36MW, and the comprehensive efficiency can reach 86% when (P1+ P3+ H1+ H2)/(Q1+ Q2). The method meets the requirement of the 'temporary method for distributed power generation management' of the national development and transformation commission on the efficiency of the distributed natural gas power station being higher than 75 percent, and has very good benefit in arrangement at the user side.

The economy of the internal combustion engine molten salt steam combined cycle power generation system of the embodiment is calculated as follows:

(1) analysis of investment costs

The unit kW cost of the internal combustion engine is 5000 yuan/kW, and the total cost is 3.6 million yuan;

the unit kW cost of the steam turbine set is 1500 yuan/kW, and the total cost is 3000 ten thousand yuan;

the total cost of the heat exchanger and the steam generator is 2000 ten thousand yuan;

the cost of molten salt unit MWh is 20 ten thousand yuan, and the total cost is 2800 ten thousand yuan.

Other investments were estimated at 1000 yuan/kW.

The total investment is 5.28 billion yuan.

(2) Revenue analysis

The electricity price is 0.9927, 0.8791, 0.5951 and 0.3111 yuan/kWh respectively according to the peak-valley electricity price (35kV and above) of the current large industry in 2021 of Shandong province. The actual settlement price is considered as floating 0.05 yuan/kWh under the catalog price.

Only the power generation in the flat period, the peak period and the peak period is considered, the generation hours are 5475 hours of annual power generation income, the annual power generation amount is 5 hundred million kilowatt hours, and the power charge income is 3.6 million yuan.

(3) Expenditure analysis of fused salt steam combined cycle power generation system of internal combustion engine

The gas price is 2.5 yuan/Nm 3. The annual consumption of natural gas is 9073 million cubic meters, and the expenditure of the natural gas is 2.26 million yuan.

The electricity consumption in the low ebb is 6570 ten thousand kWh, and the electricity fee expenditure is 2044 ten thousand yuan.

The expenditure of operation and maintenance is considered as 0.02 yuan/kWh, and 1000 ten thousand yuan is spent on annual operation and maintenance.

The annual expenditure of the project is 2.56 billion yuan.

(4) The project investment profitability is estimated to be about 12% preliminarily.

(5) If frequency modulation income is further considered, the annual frequency modulation income can reach 3000 ten thousand yuan; the project investment profitability will further increase.

The utility model aims to protect a fused salt steam combined cycle power generation system of an internal combustion engine, which comprises: the internal combustion engine 1 drives the first generator 13 to generate electricity, the steam turbine 9 drives the second generator 15 to generate electricity, and an inlet and an outlet of the steam turbine 9 are communicated through a steam pipeline; the steam pipeline enters the steam-molten salt heat exchanger 5 to exchange heat with high-temperature molten salt in the molten salt pipeline, so that low-pressure saturated steam in the steam pipeline is heated into superheated steam and then conveyed to the steam turbine 9. The utility model utilizes high-temperature molten salt to heat steam in a gradient manner, ensures that the temperature of main steam does not rise rapidly to a large extent while the load of the internal combustion engine 1 is increased rapidly, and ensures that the temperature of main steam does not drop rapidly to a large extent while the load of the internal combustion engine 1 is reduced rapidly, thereby improving the parameter and the thermal efficiency of the main steam of the steam turbine 9, obviously improving the power generation efficiency of the combined cycle of the internal combustion engine, and obviously improving the peak-load and frequency modulation capability.

It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explaining the principles of the utility model and are not to be construed as limiting the utility model. Therefore, any modification, equivalent replacement, improvement and the like made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundaries of the appended claims or the equivalents of such scope and boundaries.

Claims

1. An internal combustion engine fused salt steam combined cycle power generation system, comprising:

an internal combustion engine (1) for driving a first generator (13) to generate electricity;

the steam turbine (9) drives the second generator (15) to generate electricity;

two ports of the steam pipeline are respectively communicated with an inlet and an outlet of the steam turbine (9);

the steam-molten salt heat exchanger (5) is used for exchanging heat with a molten salt pipeline in the steam-molten salt heat exchanger (5) through the steam pipeline, so that low-pressure saturated steam in the steam pipeline is heated into superheated steam and conveyed to the steam turbine (9).

2. The internal combustion engine molten salt steam combined cycle power generation system of claim 1, further comprising: a low-temperature molten salt storage tank (6) for storing low-temperature liquid molten salt and a high-temperature molten salt storage tank (7) for storing high-temperature molten salt;

the outlet of the low-temperature molten salt storage tank (6) is communicated with the inlet of the high-temperature molten salt storage tank (7) through the molten salt pipeline, and the inlet of the low-temperature molten salt storage tank (6) is communicated with the outlet of the high-temperature molten salt storage tank (7) through the molten salt pipeline;

a molten salt electric heater (10) is arranged on the molten salt pipeline between the outlet of the low-temperature molten salt storage tank (6) and the inlet of the high-temperature molten salt storage tank (7), low-temperature liquid molten salt output from the outlet of the low-temperature molten salt storage tank (6) is heated into high-temperature liquid molten salt, and the high-temperature liquid molten salt is stored in the high-temperature molten salt storage tank (7);

and the molten salt pipeline between the inlet of the low-temperature molten salt storage tank (6) and the outlet of the high-temperature molten salt storage tank (7) enters the steam-molten salt heat exchanger (5) to transfer the heat of the high-temperature liquid molten salt to the steam pipeline.

3. The internal combustion engine molten salt steam combined cycle power generation system of claim 2, further comprising: a molten salt circulation pump (8);

the molten salt circulating pump (8) is arranged at the outlet of the low-temperature molten salt storage tank (6) to adjust the flow speed of the output low-temperature liquid molten salt; and/or

The molten salt circulating pump (8) is arranged at the outlet of the high-temperature molten salt storage tank (7) to adjust the flow speed of the output high-temperature liquid molten salt.

4. The internal combustion engine molten salt steam combined cycle power generation system of claim 1, further comprising: an evaporator (3);

the steam pipeline sequentially enters the evaporator (3), the steam-molten salt heat exchanger (5) and the steam turbine (9);

a flue gas pipeline of the internal combustion engine (1) enters the evaporator (3), low-pressure saturated steam in the steam pipeline exchanges heat with high-temperature flue gas in the flue gas pipeline to form superheated steam, and the superheated steam enters the steam-molten salt heat exchanger (5) and then exchanges heat with high-temperature liquid molten salt in the molten salt pipeline for the second time.

5. The internal combustion engine molten salt steam combined cycle power generation system of claim 1, further comprising: an evaporator (3);

the steam pipeline sequentially enters one side of the evaporator (3), the steam-molten salt heat exchanger (5) and the steam turbine (9), and the molten salt pipeline sequentially enters the other side of the steam-molten salt heat exchanger (5) and the evaporator (3);

the low-pressure saturated steam in the steam pipeline and the medium-temperature liquid molten salt in the molten salt pipeline form superheated steam after primary heat exchange in the evaporator (3), and the superheated steam enters the steam-molten salt heat exchanger (5) and then carries out secondary heat exchange with the high-temperature liquid molten salt in the molten salt pipeline.

6. An internal combustion engine molten salt steam combined cycle power generation system as claimed in claim 4 or 5, further comprising: a low-temperature flue gas heat exchanger (2);

the steam pipeline sequentially penetrates through the low-temperature flue gas heat exchanger (2) and one side of the evaporator (3), and the flue gas pipeline of the internal combustion engine (1) sequentially penetrates through the evaporator (3) and the other side of the low-temperature flue gas heat exchanger (2), so that high-temperature flue gas in the flue gas pipeline exchanges heat for the steam pipeline.

7. The internal combustion engine molten salt steam combined cycle power generation system of claim 1, further comprising: a condenser (11);

the condenser (11) is arranged at an outlet of the steam turbine (9), and the steam pipeline enters the condenser (11) to condense low-pressure saturated steam discharged from the outlet of the steam turbine (9) into water.

8. The internal combustion engine molten salt steam combined cycle power generation system of claim 7, further comprising: a water heat exchanger (4);

the water pipeline of the internal combustion engine (1) is communicated with the internal combustion engine (1) and the water heat exchanger (4) in a circulating mode;

the steam pipeline sequentially enters the condenser (11) and the water heat exchanger (4);

and low-pressure saturated steam in the steam pipeline is condensed into water in the condenser (11), and the water enters the water heat exchanger (4) and exchanges heat with cylinder sleeve water in the water pipeline.

9. The internal combustion engine molten salt steam combined cycle power generation system of claim 8, further comprising: a deaerator (12);

the deaerator (12) is arranged at an outlet of the water heat exchanger (4), the steam pipeline for heat exchange in the water heat exchanger (4) enters the deaerator (12), and the deaerator (12) removes dissolved oxygen and other gases in water.

10. An internal combustion engine molten salt steam combined cycle power generation system as claimed in claim 2,

the low-temperature liquid molten salt is nitrate, and the storage temperature is 280 ℃;

the high-temperature liquid molten salt is nitrate, and the storage temperature is 565 ℃.