An internal combustion engine power generation system of a heat storage combined chemical regenerative cycle

Abstract

The application provides a heat storage combined chemical regenerative cycle internal combustion engine power generation system and relates to the technical field of internal combustion engine power generation, which comprises a water system, a molten salt heat storage system and a chemical regenerative system; the water system is used for supplying superheated steam; the molten salt heat storage system comprises connected hot salt tanks and cold salt tanks and is used for heat energy storage; the chemical regenerative system comprises a chemical regenerator and is used for chemical regenerative reaction through superheated steam, fuel and heat energy; the internal combustion engine power generation system comprises connected internal combustion engines and generators and is used for power generation through synthesis gas; the chemical regenerative system is connected with the water system and the molten salt heat storage system; the internal combustion engine power generation system is connected with the water system and the chemical regenerative system; the application is suitable for power generation of the internal combustion engine and can improve the cycle efficiency of the internal combustion engine power generation through heat storage and combined chemical circulation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of internal combustion engine power generation, in particular to an internal combustion engine power generation system with heat storage and combined chemical regenerative cycle. BACKGROUND

[0002] In the future, wind power and photovoltaic power generation will gradually become the main power source. Wind power and photovoltaic power generation have significant intermittency and volatility characteristics. The demand for frequency regulation of the power system continues to increase. The power system needs to respond to the power fluctuation of wind power and photovoltaic power with greater amplitude, faster speed and higher accuracy, to ensure the power balance of the power system and realize large-scale utilization of renewable energy. With the continuous and rapid increase of the proportion of wind power and photovoltaic power generation, the existing frequency regulation power supply will not be able to meet the system peak regulation and frequency regulation demand, and the power system urgently needs to supplement new peak regulation and frequency regulation power supply.

[0003] Coal-fired units have large single-machine power generation scale and can meet the demand for large-scale frequency regulation, but due to low response speed and poor accuracy, and economic problems during frequency regulation, they cannot provide high-quality frequency regulation services alone. Gas internal combustion engine power generation is a heat engine that converts the heat energy released by fuel combustion in the machine into power. The internal combustion engine has strong compatibility for fuel and can use natural gas, LNG and synthetic gas as primary fuel. Internal combustion engine power generation is a relatively mature power generation technology. Internal combustion engine generator sets have the characteristics of fast regulation speed and high regulation accuracy. The start-stop time is less than 1 minute, and the frequency regulation rate can reach 60%-100% of the rated output per minute, which is much faster than coal-fired power generation and gas turbine power generation. The regulation performance is basically comparable to that of electrochemical energy storage. However, the single-machine power generation scale of internal combustion engine is small, with a single capacity of several hundred kilowatts to several megawatts, which is much smaller than the scale of existing large power plants, and cannot meet the demand for large-scale frequency regulation alone. At the same time, the efficiency of single-cycle internal combustion engine is low, about 45%, and the efficiency of combined cycle is slightly higher but not obvious, about 48%, and the frequency regulation performance decreases.

[0004] Therefore, the internal combustion engine power generation system needs to be further improved. SUMMARY

[0005] The present application relates to the technical field of internal combustion engine power generation, in particular to an internal combustion engine power generation system with heat storage and combined chemical regenerative cycle.

[0006] The embodiment of the present application realizes the technical scheme as follows: a heat storage combined chemical regenerative cycle internal combustion engine power generation system, comprising: a water system for supplying superheated steam; a molten salt heat storage system comprising connected hot salt tanks and cold salt tanks for heat energy storage; a chemical regenerative system comprising a chemical regenerator for chemical regenerative reaction by superheated steam, fuel and heat energy; an internal combustion engine power generation system comprising connected internal combustion engine and generator for power generation by synthesis gas; the chemical regenerative system is connected with the water system and the molten salt heat storage system, and the internal combustion engine power generation system is connected with the water system and the chemical regenerative system.

[0007] Further, the water system comprises connected preheater, saturator, flash evaporator and superheater, and the preheater is provided with make-up water.

[0008] Further, the chemical regenerator is provided with fuel, and the chemical reaction formula of the fuel is:

[0009]

[0010] wherein m is the hydrogen-carbon ratio of the fuel, determined by the quality of the fuel, and m is determined when the fuel is determined; R is the water-carbon ratio, set according to the requirement; a and b are the measurement coefficients of CO and CO2.

[0011] Further, the fuel is methane, and the chemical reaction formula of the methane is:

[0012] CH4+H2O=CO+3H2

[0013] CH4+2H2O=CO2+4H2

[0014] Further, the fuel is alkane, and the chemical reaction formula of the alkane is:

[0015] C n H 2n+2 +nH2O=nCO+(2n+1)H2

[0016] C n H 2n+2 +2nH2O=nCO2+(3n+1)H2.

[0017] Further, the fuel is alkene, and the chemical reaction formula of the alkene is:

[0018] C n H 2n +nH2O=nCO+2nH2

[0019] C n H 2n +2nH2O=nCO2+3nH2

[0020] Further, the internal combustion engine is connected with the chemical regenerator and the water system, and the generator is connected with the spot power market to provide electric energy.

[0021] The technical scheme of the present application has at least the following advantages and beneficial effects: first, through the arrangement of the water system, the preheating can be recovered by steam conversion reaction, avoiding energy waste caused by high exhaust temperature of the gas turbine; second, through the arrangement of the molten salt heat storage system, high-quality heat energy storage can be realized by using low-valley electricity or low-estimated heat; third, through the arrangement of the chemical regenerator system, the chemical regenerating reaction can be carried out by using the superheated steam of the water system and the heat energy of the molten salt heat storage system, thereby generating synthetic gas; finally, through the arrangement of the internal combustion engine power generation system, the synthetic gas can be used for power generation to provide electric energy and peak regulation and frequency modulation services, and the waste heat generated in the power generation process is injected into the water system for recycling, thereby improving the cycle efficiency of the internal combustion engine power generation system. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical scheme of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0023] Figure 1 The synthetic gas reaction equilibrium constant and temperature relationship diagram of the heat storage combined chemical regenerating cycle provided by the embodiments of the present application.

[0024] Figure 2 The structural schematic diagram of the internal combustion engine power generation system of the heat storage combined chemical regenerating cycle provided by the embodiments of the present application.

[0025] Legend: 1-water system, 2-molten salt heat storage system, 3-chemical regenerator system, 4-internal combustion engine power generation system, 11-preheater, 12-saturator, 13-flash evaporator, 14-superheater, 21-hot salt tank, 22-cold salt tank, 31-chemical regenerator, 41-internal combustion engine, 42-generator. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0027] The following detailed description of embodiments of the application provided in the accompanying drawings is not intended to limit the scope of the application claimed, but merely represents selected embodiments of the application. Based upon the embodiments in the application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of the application.

[0028] Embodiments

[0029] The present embodiment provides a heat storage combined chemical regenerative cycle internal combustion engine power generation system, comprising: a water system 1 for supplying superheated steam; a molten salt heat storage system 2 comprising a hot salt tank 21 and a cold salt tank 22 connected for heat energy storage; a chemical regenerative system 3 comprising a chemical regenerator 31 for chemical regenerative reaction by superheated steam, fuel and heat energy; an internal combustion engine power generation system 4 comprising an internal combustion engine 41 and a generator 42 connected for power generation by synthesis gas; the chemical regenerative system 3 is connected with the water system 1 and the molten salt heat storage system 2, and the internal combustion engine power generation system 4 is connected with the water system 1 and the chemical regenerative system 3.

[0030] It is worth mentioning that, first of all, through the setting of the water system 1, the preheating can be recovered by steam conversion reaction, avoiding energy waste caused by high exhaust temperature of the gas turbine; secondly, through the setting of the molten salt heat storage system 2, high-quality heat energy storage can be carried out by using off-peak electricity or low heat; thirdly, through the setting of the chemical regenerative system 3, chemical regenerative reaction can be carried out by using superheated steam of the water system 1, fuel and heat energy of the molten salt heat storage system 2, and then synthesis gas is generated; finally, through the setting of the internal combustion engine 41 power generation system 4, power generation can be carried out by using synthesis gas to provide electric energy and peak shaving and frequency modulation services, and the waste heat generated in the power generation process is injected into the water system 1 for recycling, thereby improving the cycle efficiency of the internal combustion engine 41 power generation system 4.

[0031] The heat storage combined chemical regenerative cycle internal combustion engine power generation system 4 of the present embodiment is based on chemical regenerative cycle, which combines coal-fired unit, molten salt heat storage and internal combustion engine for power generation; the synthesis gas reaction in the chemical regenerative cycle is a reversible reaction, the pressure range for generating synthesis gas in the forward direction is 3-5 MPa, and the temperature is 600-1000℃, and the higher the temperature, the higher the forward conversion efficiency, and the relationship between the synthesis gas reaction equilibrium constant and the temperature is as shown in Figure 1 .

[0032] Since the exhaust gas temperature of the internal combustion engine power generation is low, it cannot be operated alone for chemical regenerative cycle, so the molten salt heat storage is combined with the internal combustion engine exhaust gas waste heat to provide the heat for chemical regenerative cycle; at the same time, the molten salt is coupled with coal power, and when the electricity consumption is low, the molten salt stores heat and is combined with the internal combustion engine flue gas waste heat for chemical regenerative cycle, and the principle is as shown in Figure 2As shown, the internal combustion engine power generation system combined with heat storage and chemical regenerative cycle includes an internal combustion engine power generation system 4, a molten salt heat storage system 2, a water system 1, and a chemical regenerative system 3. The water system 1 includes a preheater 11, a saturator 12, a flash evaporator 13, and a superheater 14 connected in series, and the chemical regenerative system 3 includes a chemical regenerator 31.

[0033] The water system 1 mainly uses the waste heat of the internal combustion engine 41 to exchange heat and convert the make-up water into superheated steam. The make-up water is preheated by the preheater 11, then saturated steam is generated by the saturator 12, and finally superheated steam is generated by the superheater 14 to supply the chemical regenerator 31 for chemical reaction to produce synthesis gas.

[0034] The molten salt heat storage system 2 mainly uses low-valley electricity or low-valley heat to store high-quality heat energy, and the high-quality heat energy is introduced into the chemical regenerator 31 through a heat exchange device to promote the forward chemical reaction in the regenerator, thereby producing synthesis gas.

[0035] The internal combustion engine power generation system 4 mainly uses synthesis gas to generate electricity, which is connected to the spot power market through the generator 42 to provide power and peak load regulation and frequency regulation services, and the waste heat generated during the power generation process is injected into the water system 1 for cascade recycling.

[0036] The chemical regenerative system 3 mainly uses the superheated steam provided by the water system 1, fuel, and high-quality heat provided by the molten salt heat storage to perform chemical regenerative reaction, thereby producing synthesis gas and improving thermal efficiency. The specific chemical reaction formula is as follows:

[0037]

[0038] wherein m is the hydrogen-carbon ratio of the fuel, which is determined by the fuel quality; R is the water-carbon ratio, which is set according to the needs; a and b are the measurement coefficients of CO and CO2. Specifically:

[0039] For methane:

[0040] CH4+H2O=CO+3H2

[0041] CH4+2H2O=CO2+4H2

[0042] For alkanes:

[0043] C n H 2n+2 +nH2O=nCO+(2n+1)H2

[0044] C n H 2n+2 +2nH2O=nCO2+(3n+1)H2

[0045] for olefins:

[0046] C n H 2n + nH2O = nCO + 2nH2

[0047] C n H 2n + 2nH2O = nCO2+ 3nH2

[0048] It should be noted that if the simple cycle gas turbine exhaust temperature is high, the exhaust heat loss is large, and part of the fuel energy is wasted. The use of steam conversion reaction to recover turbine exhaust waste heat can overcome this shortcoming. The chemical regenerative gas turbine cycle increases the fuel heat value by absorbing exhaust waste heat, thereby improving the cycle efficiency. In addition, the fuel conversion products contain hydrogen, and mixing about 5% hydrogen in gasoline and diesel can improve the compression ratio and achieve lean combustion, which helps to increase the exhaust gas recirculation amount and reduce the use of fossil fuels during the starting process, and helps the unit flexibility operation. Such combustion effect can greatly reduce the emission of hydrocarbons and NOx in the tail gas. Hydrogen mixing combustion is an important means to achieve various tail gas emission standards. The gaseous products after fuel conversion are convenient for mixing combustion with air, among which hydrogen plays a role in strengthening combustion and reducing the temperature in the combustion core area. The thermal efficiency of this cycle can reach more than 50%, and the NOx emission can be reduced to below ppm; finally, the chemical regenerative gas turbine cycle uses excess steam injected into the combustion chamber during the fuel conversion process, so the chemical regenerative gas turbine cycle has the characteristics and advantages of steam injection cycle.

[0049] For example, a 252MW internal combustion engine power plant is configured with a 20MW water system and a 20MW chemical regenerative system supplied by a molten salt heat storage system. If this technical solution is not adopted, 131-139MW of flue gas waste heat is directly discharged, and the single cycle efficiency of the internal combustion engine power system 4 is between 45%-48%. As shown in the table, after adopting this scheme, the water system 1 uses the flue gas waste heat of the internal combustion engine power system 4 for heat exchange, and converts 418.3kJ / kg of make-up water into 3010.4kJ / kg of superheated steam; the chemical regenerative system 3 uses the superheated steam provided by the water system 1 and the high-quality heat provided by the molten salt heat storage system 2 to carry out chemical regenerative reaction to produce synthesis gas. The modified heat storage combined chemical regenerative cycle internal combustion engine power system 4 can increase the waste heat utilization by 20MW, and the overall system efficiency will be improved to 53%-56%.

[0050]

[0051]

[0052] The above merely describes the preferred embodiments of the present application, and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An internal combustion engine power generation system with thermal storage combined with chemical regenerative cycle, characterized in that, include: Water system (1), the water system (1) being used to supply superheated steam; Molten salt thermal storage system (2) includes a connected hot salt tank (21) and a cold salt tank (22) for storing thermal energy; A chemical regenerative system (3) includes a chemical regenerator (31) for carrying out a chemical regenerative reaction using the superheated steam, fuel and the heat energy; An internal combustion engine power generation system (4) includes a connected internal combustion engine (41) and a generator (42) for generating electricity using syngas; The chemical regeneration system (3) is connected to the water system (1) and the molten salt thermal storage system (2), and the internal combustion engine power generation system (4) is connected to the water system (1) and the chemical regeneration system (3); The water system (1) includes a preheater (11), a saturator (12), a flash evaporator (13) and a superheater (14) connected together, and the preheater (11) is supplied with makeup water; The chemical regenerator (31) contains fuel, and the general chemical reaction formula of the fuel is: Where m is the hydrogen-to-carbon ratio of the fuel, which is determined by the fuel quality; once the fuel is determined, m is also determined. R is the water-to-carbon ratio, which is set as needed. a and b are the measurement coefficients for CO and CO2. The fuel is methane, and the chemical reaction formula for methane is: ； The internal combustion engine (41) is connected to the chemical regenerator (31) and to the water system (1), and the generator (42) is connected to the spot electricity market to provide electrical energy.

2. The internal combustion engine power generation system with thermal storage combined with chemical regenerative cycle as described in claim 1, characterized in that, The fuel is an alkane, and the chemical reaction formula of the alkane is: 。 3. The internal combustion engine power generation system with thermal storage combined with chemical regenerative cycle as described in claim 1, characterized in that, The fuel is an olefin, and the chemical reaction formula of the olefin is: 。

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