Method for afterburning low-calorific-value combustible gas in tail gas of gas turbine

Abstract

The invention discloses a method for afterburning low-heat-value combustible gas in tail gas of a gas turbine. A heat accumulating type flameless combustion furnace is arranged below a tail gas channel between a gas turbine outlet of the GTCC and a waste heat pot. Low-heat-value combustible gases such as various volatile organic compounds, combustible waste gas and tail gas in a chemical production system are heated by utilizing a small amount of fuel gas tail gas and then are introduced into the heat accumulating type flameless combustion furnace; chemical heat of low-calorific-value combustible gas is converted into physical sensible heat higher than the tail gas temperature of the gas turbine in the heat accumulating type flameless combustion furnace under the conditions of the tail gas temperature and oxygen concentration of the gas turbine by utilizing the temperature and oxygen of the tail gas of the gas turbine, so that the high-level enthalpy of the tail gas of the gas turbine is increased or even greatly increased; and further, preconditions are created for high-efficiency conversion of the low-heating-value fuel gas. The method is used for high-efficiency recycling of low-calorific-value and ultralow-calorific-value fuel gas such as chemical and metallurgical tail gas and coal bed gas, and meanwhile, various VOCs released by chemical production are subjected to low-cost innocent treatment together with the high-efficiency recycling of the low-calorific-value and ultralow-calorific-value fuel gas.

Description

Technical Field

[0001] The present invention relates to the technical field of power generation, and in particular to a system and method for supplementary combustion of exhaust gas from a combustion engine of a GTCC Brayton-Rankine combined cycle. Background Art

[0002] Low calorific value gas can be divided into three categories according to the calorific value of the gas fuel itself. The calorific value is greater than 3600kcal / Nm 3 High calorific value fuel, calorific value is 1500~3600kcal / Nm 3 The fuel is medium calorific value fuel, and the calorific value is less than 1500kcal / Nm 3 Low calorific value fuel. In industrial production, a large number of fuels, especially those with calorific value of 200-800kcal / Nm 3 Ultra-low calorific value gas fuels mainly include various product tail gases in the petrochemical production process, blast furnace gas in the steel industry, smelting tail gases in the metallurgical industry; low-concentration gas (coalbed methane) and semi-coke (semi-coke) tail gases in coal mining; various absorption, separation, and distillation separation tail gases in organic chemicals, natural gas chemicals, and coal chemicals, product synthesis tail gases, volatile organic compounds (VOCs), etc. In addition, the combustible gases with components such as H2, CO, N2, CO2, and CH4 produced by pyrolysis and gasification of biomass, the biogas produced by the breeding industry, and the combustible gases mainly composed of CH4 and CO2 produced by landfills usually have low calorific values ​​before the non-combustible components are removed, and they are also low calorific value gases.

[0003] Due to the low calorific value and economic value of these tail gases, it is impossible to transport them for sale over long distances or to centrally process them. The heat recovery method for these low calorific value gases is usually to install a small-scale open flame combustion boiler near the installation site or in the system, or to use a regenerative flameless combustion boiler to convert them into process steam or generate electricity, or simply burn them into a flare.

[0004] At present, the relatively mature low calorific value gas heat recovery methods in the steel industry mainly include gas steam combined cycle (CCPP) and subcritical gas power generation (BTG). CCPP is used for low calorific value blast furnace gas power generation. Since the blast furnace gas at normal pressure needs to be compressed before entering the low calorific value gas turbine, although the overall power generation thermal efficiency can reach 45%, the investment is nearly 2 times higher than that of subcritical gas power generation (BTG), and the increased investment needs more than 10 years to recover the increased power generation benefits; although subcritical gas power generation (BTG) has low investment, the power generation thermal efficiency is only 40%. Both have unsatisfactory aspects under the need for energy conservation, emission reduction and cost reduction. Since the amount of low calorific value tail gas in the chemical industry is far less than that of blast furnace gas, and the calorific value and gas volume are constantly fluctuating, CCPP and BTG technologies have not been applied in the chemical industry and other industries.

[0005] CN104976616B is a low calorific value gas high temperature air combustion furnace with water-cooled wall. The pressurized air is heated by a heat storage heat exchanger, and then burned with low calorific value coal gas in a 1400℃ radiation water-cooled wall combustion furnace. After radiating the heat to the circulating water in the water-cooled wall, the remaining heat heats the heat storage furnace again, and then goes to the expander to do work after the temperature drops to 600℃. This method of first exchanging high-level heat energy to the liquid water working medium of the water-cooled wall will significantly reduce the thermal efficiency due to the huge condensation heat loss of the water working medium; the energy recovery of the 600℃ flue gas entering the expander to do work is not entirely reasonable due to the low temperature.

[0006] CN109323251B discloses a flameless combustion system and method for low calorific value fuel gas, wherein an air cooling pipe is arranged between the air supply device and the burner, and the middle section of the air cooling pipe extends into the furnace along the inner wall of the furnace, and the normal temperature air is preheated in the furnace and then transported to the burner. This method of heating the combustion air by heat release from the combustion of low calorific value fuel does not make better use of the chemical heat in the low calorific value fuel gas.

[0007] CN108954374B combined cycle waste heat boiler supplementary combustion air system, because the supplementary combustion gas and oil fuels cannot rely on the residual oxygen in the exhaust gas of the gas engine for full combustion, proposes a method of adding supplementary combustion air which is simple and feasible. However, it not only fails to fully utilize the large amount of high-concentration oxygen in the exhaust gas of the gas engine, but the added supplementary combustion air also increases the total flue gas flow, exhaust heat and total resistance, which is obviously not ideal.

[0008] As a traditional power generation equipment, GTCC combined cycle power generation fueled by natural gas or oil has been widely used in Europe and the United States, where oil and natural gas are the main energy sources. Due to its high energy conversion efficiency, rapid load regulation, small footprint, and excellent environmental protection effect, it is not only used as a basic power supply equipment, but also has become a peak-shaving power supply with fast regulation rate and low cost to help large-scale access to the grid for wind and solar power in the current era of the rise of wind and solar power. It is precisely because of the many advantages of combined cycle power generation that it is also widely used in various industries such as petroleum refining and natural gas chemical industry. The combustion of gas turbine exhaust gas is also widely used, and its main purpose is to adjust the steam production of waste heat boilers. The fuel is usually a liquid or gas fuel that is the same as the gas turbine fuel or has a higher calorific value. There is no case of using low calorific value, even ultra-low calorific value fuel, or low calorific value gas with VOCs volatile organic compounds for combustion. Summary of the invention

[0009] The purpose of the present invention is to provide a method for the society to utilize the temperature of the exhaust gas of the gas turbine and the oxygen therein to convert the chemical combustion heat of low calorific value combustible gas, or low calorific value fuel gas into which VOCs volatile organic compounds are introduced, or combustible liquid, or combustible powder into physical sensible heat higher than the temperature of the exhaust gas of the gas turbine under the conditions of the temperature and oxygen concentration of the exhaust gas of the gas turbine, thereby increasing or even substantially increasing the high-order thermal enthalpy of the exhaust gas of the gas turbine, thereby creating key prerequisites for improving the energy conversion efficiency, steam pressure, effective energy and steam thermal cycle efficiency of the waste heat boiler, and also utilizing the temperature and residual oxygen of the exhaust gas of the gas turbine to improve the energy conversion efficiency of the low calorific value fuel gas while converting the VOCs volatile organic compounds that pollute the environment into CO2 and H2O.

[0010] 1. A method for supplementing combustion of low calorific value combustible gas with exhaust gas from a combustion engine, characterized in that a regenerative flameless combustion furnace (5) is arranged below an exhaust gas passage (2) between an outlet of a gas turbine (1) and a waste heat boiler (3) (see Figure 1 , Figure 2 ); a small amount of high-temperature exhaust gas (6A) of the combustion engine is drawn out from the side wall of the exhaust passage (2) and passes through the heat exchanger (6) to heat the normal-temperature low-calorific value fuel gas (6D) into high-temperature low-calorific value fuel gas (6E); the high-temperature low-calorific value fuel gas (6E) passes through the low-calorific value fuel gas distribution pipe (5F) and the low-calorific value fuel gas branch pipe (5D), and is mixed with the high-temperature exhaust gas (6A) of the combustion engine from the combustion engine exhaust gas downward passage (5C) on the other side of the heat storage type flameless combustion furnace (5) at the bottom of the heat storage type flameless combustion furnace (5), and then passes through the lower chamber (5S) to enter the heat storage section (5R). While being heated by the heat storage bricks, the oxygen in the combustion engine exhaust gas and the combustible components in the low-calorific value fuel gas are mixed in the heat storage section (5R). The two gases meet in the hot section (5R) space or on the surface of the heat storage bricks to chemically burn and release heat energy, thereby realizing that the low calorific value fuel gas utilizes the residual oxygen in the exhaust gas of the combustion engine to stably burn without flame at 800-900°C above the exhaust temperature of the combustion engine, and while heating the heat storage bricks, the temperature of the exhaust gas of the combustion engine is increased to 800-900°C to become high-temperature flue gas (5E); the high-temperature flue gas (5E) then enters the high-temperature flue gas distribution pipe (5P) arranged in the exhaust gas channel (2), and is distributed in the exhaust gas of the combustion engine flowing outside the high-temperature flue gas distribution pipe (5P), thereby realizing the purpose of supplementary combustion with the low calorific value combustible gas and heating all the exhaust gas of the combustion engine entering the waste heat boiler (3).

[0011] 2. A method for supplementing combustion of low calorific value combustible gas with exhaust gas of a combustion engine, characterized in that a venturi injector (5U), a low calorific value gas branch pipe (5D), and a low calorific value gas distribution pipe (5F) (see Figure 3 , Figure 4); utilizing the negative pressure generated by the high-speed ejection of low calorific value combustible exhaust gas from the nozzle of the venturi ejector (5U) to draw in the exhaust gas of the engine that flows into the lower part of the partition (GB) through the exhaust gas downward passage (5C) of the engine, and mix with it and make it rise; the mixed exhaust gas of the engine and the low calorific value combustion gas is called a mixed gas, and while the mixed gas is mixed again in the lower chamber (5S) above the partition (GB), the kinetic energy of the ejected gas is converted into static pressure energy, which becomes the driving pressure for pushing the high-temperature flue gas (5E) upward; the mixed gas enters the heat storage section (5R), and while being heated by the heat storage bricks of the heat storage section (5R), the combustible components in the mixed gas meet with oxygen on the surface of the heat storage bricks and chemically burn to release heat energy, thereby realizing that the low calorific value combustion gas utilizes the residual oxygen in the exhaust gas of the engine to stably burn without flames above the exhaust temperature of the engine, and while heating the heat storage bricks, the temperature of the exhaust gas of the engine is raised to 800-900°C to become high-temperature flue gas.

[0012] 3. A method for supplementing combustion of low calorific value combustible gas with exhaust gas of a gas turbine, characterized in that a regenerative flameless combustion furnace (5) is arranged below the exhaust gas passage (2) between the exhaust gas outlet of the gas turbine (1) and the waste heat boiler (3) (see Figure 1 , Figure 2 ), and a partition groove (5V) is provided below the lower chamber (5S) of the regenerative flameless combustion furnace (5) (see Figure 5 , Figure 6 ); the exhaust gas (RJWQ) of the engine flowing through the exhaust duct (5H) and the exhaust gas descending channel (5C) of the engine, and the low calorific value gas (GRZRQ) flowing through the low calorific value gas distribution pipe (5F) and the low calorific value gas branch pipe (5D) can enter the separation groove (5V) through both sides of the furnace body (5B), and then rise into the lower chamber (5S) to mix and then enter the heat storage section (5R) (see Figure 5 , Figure 6 ); The mixed gas turbine exhaust gas and low calorific value fuel gas are called mixed gas. When the mixed gas is heated by the heat storage bricks of the heat storage section (5R), the combustible components in the mixed gas meet with oxygen on the surface of the heat storage bricks and undergo chemical combustion to release heat energy, thereby achieving stable flameless combustion above the exhaust temperature of the fuel turbine by utilizing the residual oxygen in the fuel turbine exhaust gas. While heating the heat storage bricks, the fuel turbine exhaust gas temperature is raised to 800-900°C to become high-temperature flue gas.

[0013] 4. A method for stably burning low calorific value fuel gas with a low calorific value fuel gas in the exhaust gas of the gas turbine when the gas turbine is stopped, characterized in that a regenerative flameless combustion furnace (5) is arranged below the exhaust gas passage (2) between the exhaust gas outlet of the gas turbine (1) and the waste heat boiler (3) (see Figure 1 , Figure 2 , Figure 7 ); Installed at the bottom of the partition groove (5V) of the regenerative flameless combustion furnace (5) to provide high calorific value (calorific value ≥ 1500kcal / Nm3 ) The high calorific value gas distribution pipe (5L) of the gas is installed in the exhaust gas tank (RJWQC) of the gas turbine, and the high calorific value gas branch pipe (5L) and the burner (5W) are installed (see Figure 7 , Figure 8 , Fig. 9 ); Install the combustion air distribution pipe (5I) and the combustion air branch pipe (5J) on the outside of the engine exhaust gas downward passage (5K) (see Figure 7 ); a duct door (5G) is provided at the air inlet of the engine exhaust duct (5H); and a liftable flue gas damper (2A) is provided at the engine exhaust outlet;

[0014] During the shutdown period of the gas turbine, there is no exhaust gas from the gas turbine, and the duct door (5G) is closed to prevent the combustion air from flowing back into the exhaust channel (2); the flue gas gate (2A) is closed to prevent the high-temperature flue gas (5E) from flowing back into the gas turbine; the high calorific value gas is sent to the burner (5W) through the high calorific value gas distribution pipe (5L) and the high calorific value gas branch pipe (5M), and the combustion air is sent to the gas turbine exhaust tank (RJWQC) through the combustion air distribution pipe (5I) and the combustion air branch pipe (5J), and the high calorific value gas is burned on the burner (5W) in the gas turbine exhaust tank (RJWQC) through the installed electronic ignition device to form a permanent light. The low calorific value gas is sent to the low calorific value gas tank (DRZRQC) through the low calorific value gas distribution pipe (5F) and the low calorific value gas branch pipe (5D) by a fan. After the low calorific value gas rises in the tank, it mixes with the combustion-supporting air heated by the long-burning flame (5N) in the lower chamber (5S), rises, and enters the heat storage section (5R). The combustible components in the low calorific value gas meet with oxygen on the surface of the heat storage brick and chemically burn to release heat energy, thereby realizing stable flameless combustion of the low calorific value gas on the surface of the heat storage brick during the shutdown of the exhaust gas of the gas turbine. While heating the heat storage brick, the flue gas temperature rises to 800-900°C to become high-temperature flue gas.

[0015] 5. A method for supplementing combustion of low calorific value combustible gas with exhaust gas from a combustion engine, characterized in that a high-temperature flue gas distribution pipe (5P) with a streamlined cross section is arranged above the regenerative flameless combustion furnace (5) (see Figure 1 , Figure 7 , Fig.11 ), so that the high-temperature flue gas (5E) leaving the regenerative flameless combustion furnace can flow to the upper space of the exhaust gas channel (2), be evenly mixed with the fuel gas exhaust in the upper space and heated up before entering the waste heat boiler (3); the high-temperature flue gas distribution pipe (5P) with a streamlined cross section has the following functions: ① reducing the occupation of the chimney on the flue flow cross section to reduce the flow resistance of the engine exhaust gas; ② using the low density of the high-temperature flue gas (5E) to reduce the pressure of the regenerative section (5R) and the lower chamber (5S) in the combustion furnace, so that the engine exhaust gas enters the lower chamber (5S) of the combustion furnace to obtain the required pressure difference power; ③ the low-pressure areas on both sides of the streamlined high-temperature flue gas distribution pipe (5P) are provided with high-temperature flue gas outlets (5Q) along the height direction (see Fig.10 , Fig.11 ), so that part of the high-temperature flue gas (5E) flows out of the pipe during the ascending process and mixes with the exhaust gas of the combustion engine at different heights, thereby heating the exhaust gas of the combustion engine at different heights and making the exhaust gas temperature of the combustion engine entering the waste heat boiler uniform; at the same time, the flow velocity of the high-temperature flue gas (5E) in the streamlined high-temperature flue gas distribution pipe (5P) is reduced along the height, thereby reducing the flow resistance.

[0016] 6. A method for supplementing combustion of low calorific value combustible gas with exhaust gas of a combustion engine, characterized in that a heat exchanger (6) is arranged in the process before the low calorific value combustible gas enters the regenerative flameless combustion furnace (5) (see Figure 2 ); The heat exchanger is divided into three sections: high temperature, medium temperature and low temperature; the high temperature section adopts shell and tube heat exchange, the medium temperature section adopts circulation to hot liquid heat exchange, and the low temperature section adopts heat pipe heat exchange.

[0017] 7. A method for supplementing combustion of low calorific value combustible gas with exhaust gas from a combustion engine, characterized in that a heat exchanger (6) is arranged in the process before the low calorific value fuel gas enters the regenerative flameless combustion furnace (5), and the heat exchanger is in the form of a fixed bed switching type regenerative heat exchanger, or a rotating type regenerative heat exchanger, or a regenerative heat exchanger of a combination of a fixed bed type and a rotating bed type, or a combination of a high temperature section with regenerative heat exchange and a low temperature section with partition wall heat exchange.

[0018] 9. A method for supplementing combustion of low calorific value combustible gas with exhaust gas of a combustion engine, characterized in that when the resistance of the heat exchanger (6) and its pipeline is lower than the pressure of the exhaust gas of the combustion engine, the low temperature exhaust gas (6B) of the combustion engine is directly sent to the chimney (4) through the pipeline (see Figure 2 ) and controls its flow rate through its valve (6C).

[0019] 9. A method for supplementing combustion of low calorific value combustible gas with exhaust gas of a combustion engine, characterized in that when the resistance of the heat exchanger (6) and its pipeline is higher than the exhaust gas pressure of the combustion engine, the low temperature exhaust gas (6B) of the combustion engine is sent into the chimney (4) through the fan (C-6) (see Figure 2 The dotted line part) and its flow rate is controlled by the fan (C-6).

[0020] 10. A method for supplementing combustion of low calorific value combustible gas with exhaust gas from a combustion engine, characterized in that the low calorific value fuel gas does not pass through a heat exchanger (6), but directly enters a low calorific value fuel gas distribution pipe (5F) through a low calorific value fuel gas shortcut pipe (6F).

[0021] 11. A method for supplementing combustion of low calorific value combustible gas with engine exhaust gas, characterized in that the engine exhaust gas flow rate is controlled by controlling the opening and closing degree of a duct door (5G), thereby achieving regulation of the engine exhaust gas flow rate according to the needs of the low calorific value fuel gas flow rate, temperature, calorific value, and temperature of the heat storage section of the combustion furnace.

[0022] 12. A method for supplementing combustion of low calorific value combustible gas with engine exhaust gas, characterized in that a engine exhaust gas downward passage (5C) flowing under the partition (GB) is provided only on one side of the regenerative flameless combustion furnace.

[0023] 13. A method for supplementing combustion of low calorific value combustible gas with combustion engine exhaust gas, characterized in that a low calorific value fuel gas outlet pipe (5Y) and an outlet hole (5X) are arranged below the lower chamber (5S) to achieve mixing of the low calorific value fuel gas and combustion-supporting combustion engine exhaust gas.

[0024] 14. A method for supplementing combustion of low calorific value combustible gas with engine exhaust gas, characterized in that the supplementary combustion material entering the heat storage flameless combustion furnace is a combustible liquid or a combustible powder, and its chemical combustion heat is converted into physical sensible heat higher than the engine exhaust gas temperature under the conditions of its engine exhaust gas temperature and oxygen concentration.

[0025] 15. A method for supplementing combustion of low calorific value combustible gas with exhaust gas from a gas engine, characterized in that the combustible components of the supplementary combustion material entering the regenerative flameless combustion furnace come from the induced gas from coal gasification, flash exhaust gas, vented air from a degassing tank, low-temperature methanol-washed exhaust gas, PSA exhaust gas, coal gas water expansion gas, acid gas from a phenol-ammonia recovery deacidification tower, volatile organic compounds (VOCs) emitted from breathing valves of tanks in tank areas, liquid nitrogen-washed exhaust gas, and product synthesis exhaust gas.

[0026] The positive effects of the present invention are:

[0027] The present invention is particularly suitable for low calorific value products in the chemical industry with small output, fluctuating composition and gas volume, and even low calorific value products with calorific value as low as 200kcal / Nm 3 Various separation and purification tail gas, coal-bed methane and other industrial tail gas with ultra-low calorific value can all use the temperature of about 600°C of the engine tail gas and 10% of residual oxygen to perform high-temperature combustion and heat release in a regenerative flameless combustion furnace above the engine tail gas temperature. It not only effectively increases the high-level thermal enthalpy of the engine tail gas, but also creates key prerequisites for improving the energy conversion efficiency, steam pressure, effective energy and steam thermal cycle efficiency of the waste heat boiler; the disclosure of the present invention, in particular, provides a feasible technical solution for the efficient combustion and utilization of extremely large amounts of ultra-low calorific value coal-bed methane containing 2-5% methane, which cannot be burned by traditional processes.

[0028] Since the superheated steam pressure in the current GTCC combined cycle is mostly around 15MPa, it is 2 to 10 times higher than the pressure of the small-scale waste heat boilers in the chemical industry that only produce saturated steam. Therefore, the low calorific value industrial tail gas in the chemical industry adopts the present invention, and the high-pressure superheated steam produced by the low calorific value industrial tail gas can be used in chemical production after the pressure is reduced to the chemical process pressure after the steam turbine works, which will undoubtedly greatly improve the energy conversion efficiency of the low calorific value gas;

[0029] The use of a Venturi ejector to extract the exhaust gas from the gas turbine at high temperature greatly reduces the power consumption of the fan of the low calorific value gas. After the low calorific value exhaust gas entering the regenerative combustion furnace is pressurized at normal temperature and pressure, the high temperature of the gas turbine exhaust gas is used to increase the temperature of the low calorific value gas to a temperature close to the temperature of the gas turbine exhaust gas through a heat exchanger. Its volume expands by about 2.7 times, increasing the amount of power gas entering the Venturi ejector by 1.7 times. This can not only fully guarantee the total amount of gas turbine exhaust gas extracted and overcome the need for gas flow resistance, but also effectively reduce the low calorific value gas pressurization pressure, thereby reducing its fan power consumption;

[0030] Since the volatile organic compounds (VOCs) waste gas, odor, and various separation, purification, and synthesis tail gases in industrial production equipment such as coal chemical, petroleum, and natural gas contain combustible components in different concentrations, these waste gases and tail gases can all become low calorific value fuel gas after proper mixing and treatment. The heat storage flameless combustion method of the present invention can be used to convert the chemical combustion heat into high-temperature thermal enthalpy while converting the organic matter that pollutes the environment into CO2 and water vapor. Therefore, the investment, land occupation and operating costs of equipment specially used to treat volatile organic compounds (VOCs) waste gas and odor can be saved. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 , a simplified diagram illustrating the relative position relationship between the regenerative flameless combustion furnace and the exhaust gas channel of the gas turbine.

[0032] Figure 2 , a simplified diagram illustrating the planar layout of the heat exchanger and its related processes and the high-temperature flue gas distribution pipe in the present invention.

[0033] Figure 3 , illustrating the relevant structural schematic diagram of a regenerative flameless combustion furnace that uses a venturi ejector to extract the exhaust gas of a combustion engine.

[0034] Figure 4 , a simplified diagram illustrating the structural relationship between the low calorific value gas distribution pipe, branch pipe, ejector, and partition.

[0035] Figure 5 , a schematic diagram of the relevant structure of a regenerative flameless combustion furnace using a partition tank for gravity mixed combustion.

[0036] Figure 6 , a top view schematic diagram of the separation groove located below the lower cavity and the way in which the engine exhaust gas and low calorific value fuel gas enter the separation groove.

[0037] Figure 7 , a simplified diagram of the relevant structures required for the operation of the regenerative flameless combustion furnace when the gas turbine is shut down.

[0038] Figure 8 , a front view schematic diagram of the relationship between the components, structure, layout and partition wall of the ever-burning flame in the partition groove.

[0039] Fig. 9 , schematic diagram of the way combustion air and low calorific value gas enter the separation groove and the layout of the burner distribution pipe.

[0040] Fig.10 , schematic diagram of the high-temperature flue gas outlet on the wall of the high-temperature flue gas distribution pipe.

[0041] Fig.11 , schematic diagram of the streamlined cross-sectional shape of the high-temperature flue gas distribution pipe and the positions of the high-temperature flue gas outlets on both sides.

[0042] Fig.12 , schematic diagram of low calorific value fuel gas entering the heat storage section after mixing with the exhaust gas of the gas turbine through the pipe holes.

[0043] Fig.13 , a top view of the low calorific value fuel gas mixing with the exhaust gas of the gas turbine in the form of pipe holes for gas outlet.

[0044] In the figure:

[0045] 1. Gas engine or gas turbine;

[0046] 2. Exhaust channel;

[0047] 2A. Smoke damper;

[0048] 2B. Explosion-proof membrane;

[0049] 3. Waste heat boiler;

[0050] 4. Chimney;

[0051] 5. Regenerative flameless combustion furnace

[0052] 5A. Insulated wall;

[0053] 5B.Furnace body;

[0054] 5C. Gas turbine exhaust downward passage;

[0055] 5D. Low calorific value gas branch pipe;

[0056] 5E. High temperature flue gas and outlet;

[0057] 5F. Low calorific value gas distribution pipe;

[0058] 5G. Duct door;

[0059] 5H. Gas turbine exhaust duct;

[0060] 5I. Combustion air distribution pipe;

[0061] 5J. Combustion air branch pipe;

[0062] 5K. Partition wall;

[0063] 5L. High calorific value gas distribution pipe;

[0064] 5M. High calorific value gas branch pipe;

[0065] 5N. Eternal flame;

[0066] 5P. High temperature flue gas distribution pipe;

[0067] 5Q. High temperature flue gas outlet;

[0068] 5R. Heat storage section;

[0069] 5S. Lower cavity;

[0070] 5T. External wall;

[0071] 5U. Venturi ejector;

[0072] 5V.Separator slot;

[0073] 5W. Burner;

[0074] 5X. Low calorific value gas outlet;

[0075] 5Y. Low calorific value gas outlet pipe;

[0076] 6. Heat exchanger;

[0077] 6A. High temperature exhaust gas and pipelines of gas turbine;

[0078] 6B. Gas turbine low temperature exhaust gas and pipelines;

[0079] 6C.Valve;

[0080] 6D. Normal temperature low calorific value gas and pipelines;

[0081] 6E. High temperature low calorific value gas and pipelines;

[0082] 6F. Low calorific value gas shortcut pipe, the low calorific value gas directly enters the low calorific value gas distribution pipe (5F) without passing through the heat exchanger (6);

[0083] C-6. induced draft fan;

[0084] ZRKQ. Combustion air;

[0085] DRZRQ. Low calorific value gas;

[0086] RJWQC. Gas turbine tail gas tank;

[0087] DRZRQC. Low calorific value gas tank;

[0088] GB. Partition;

[0089] Relevant airflow direction. DETAILED DESCRIPTION

[0090] Implementation 1:

[0091] The chemical enthalpy of coal-bed methane with a methane content of 3% is 256.86 kcal / Nm 3 (1027kJ / Nm 3 ), gas volume 720000Nm 3 / h, after the fan is pressurized to a gauge pressure of 10kPa (0.1bar), the temperature rises from 27℃ to 37℃, and the shaft power is about 2800kw; it is sent to the heat exchanger through the pipeline, which is an optional heat storage heat exchanger, and exchanges heat with the 593℃ MHPS701F4 engine exhaust gas to raise the coalbed methane temperature to 550℃. After the heat exchange, the engine exhaust gas temperature drops to 70℃, and is sent to the waste heat boiler through the induced draft fan, and then heated up and exhausted to the chimney; the 550℃ coalbed methane is sent to the Venturi ejector through the low calorific value gas distribution pipe, and in its high-speed spray The negative pressure generated by the exhaust gas draws in about 2.5 times the volume of the coal-bed methane, and after mixing, it enters the regenerative flameless combustion furnace through the lower cavity. The methane and oxygen in the mixed gas meet on the surface of its regenerative bricks for chemical combustion and releases heat, which raises the temperature of the flue gas after combustion to about 820°C; the 820°C flue gas passes through the streamlined flue gas distribution pipe arranged in the exhaust gas channel, and mixes and heats the exhaust gas of the gas turbine that does not participate in the combustion on the entire exhaust gas inlet section of the waste heat boiler, so that the exhaust gas of the two MHPS701F4 units totals 1180Nm 3 / s The flue gas temperature rises to about 725℃, realizing the supplementary combustion of GTCC combined cycle gas turbine exhaust gas with ultra-low calorific value coalbed methane.

[0092] Implementation 2:

[0093] Low calorific value fuel gas composed of various process waste gases and tail gases containing volatile organic compounds (VOCs) produced by coal chemical processes, with a chemical enthalpy of 777 kcal / Nm 3 , gas volume is 144000Nm 3 / h, volume flow rate 40Nm per second 3 / h, density 1.65kg / Nm 3 , weight flow rate per second 66kg / s, temperature 27℃;

[0094] The low calorific value gas is pressurized by 20kPa through the fan, the fan efficiency is 80%, and the temperature rise is 17.5℃; the shaft power of the low calorific value gas fan is about 1050kw, and the fan outlet temperature is 44.5℃. After heat exchange with the 593℃ tail gas of the MHPS701F4 gas turbine through the fixed bed switching regenerative heat exchanger, the temperature rises to 550℃ and enters the low calorific value gas distribution pipe of the regenerative flameless combustion furnace;

[0095] The exhaust gas from the gas turbine passes through the fixed bed heat storage heat exchanger, and the temperature is reduced to 70℃ when it leaves the heat exchanger. The mass flow rate is about 67.53kg / s, and it is directly sent to the chimney through the pipeline for discharge.

[0096] The low calorific value gas with a temperature rising to 550°C enters the Venturi injector through the distribution pipe and the low calorific value gas branch pipe, and sucks in the engine exhaust gas about 6 times the injection mass to become a mixed gas. The mixed gas enters the heat storage section through the lower cavity. While the mixed gas is heated, its combustible components react chemically with oxygen to release heat, generating 850°C high-temperature flue gas, which then leaves the heat storage section and enters the high-temperature flue gas distribution pipe arranged on the cross-section of the gas turbine exhaust gas channel. While the high-temperature flue gas rises along the distribution pipe, part of the high-temperature flue gas flows into the gas turbine exhaust gas channel through outlets at different heights on the wall of the distribution pipe, and mixes with the gas turbine exhaust gas that does not participate in the combustion, so that the average temperature of the mixed gas reaches about 750°C; the 850°C high-temperature flue gas flowing out of the top of the distribution pipe mixes with the gas turbine exhaust gas at the top of the gas turbine exhaust gas channel, so that the temperature of the gas turbine exhaust gas after mixing with the top is also raised to about 750°C; thereby, the low calorific value fuel gas is used to supplement the gas turbine exhaust gas, so that the temperature of the gas turbine exhaust gas entering the waste heat boiler is raised to 750°C, and various VOCs volatile organic compounds, process combustible waste gas, and tail gas in the entire coal chemical production system are all purified in this embodiment, so that the coal chemical production of this device can achieve clean production.

[0097] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for supplementing combustion of low calorific value combustible gas with exhaust gas from a combustion engine, characterized in that: A regenerative flameless combustion furnace (5) is arranged below the exhaust gas channel (2) between the gas turbine (1) outlet and the waste heat boiler (3); a small amount of high-temperature exhaust gas (6A) of the combustion engine is drawn out from the side wall of the exhaust gas channel (2) and is used to heat the normal-temperature low-calorific value combustion gas (6D) into high-temperature low-calorific value combustion gas (6E) through a heat exchanger (6); the high-temperature low-calorific value combustion gas (6E) is mixed with the high-temperature exhaust gas (6A) of the combustion engine from the exhaust gas downward channel (5C) on the other side of the regenerative flameless combustion furnace (5) at the bottom of the regenerative flameless combustion furnace (5) through a low-calorific value combustion gas distribution pipe (5F) and a low-calorific value combustion gas branch pipe (5D), and then moves upward through a lower chamber (5S) into a regenerative section (5R), where it is heated by the regenerative bricks. The oxygen in the exhaust gas of the gas turbine meets the combustible components in the low calorific value fuel gas in the heat storage section (5R) space or on the surface of the heat storage bricks to chemically burn and release heat energy, thereby realizing the stable flameless combustion of the low calorific value fuel gas using the exhaust gas of the gas turbine at 800-900°C above the exhaust temperature of the gas turbine, and while heating the heat storage bricks, the temperature of the exhaust gas of the gas turbine is increased to 800-900°C to become high-temperature flue gas (5E); the high-temperature flue gas (5E) then enters the high-temperature flue gas distribution pipe (5P) arranged in the exhaust gas channel (2), and is distributed in the exhaust gas of the gas turbine flowing outside the high-temperature flue gas distribution pipe (5P), thereby realizing the purpose of supplementary combustion with the low calorific value combustible gas and heating all the exhaust gas of the gas turbine entering the waste heat boiler (3).

2. The method for supplementary combustion of low calorific value combustible gas with exhaust gas from a combustion engine according to claim 1, characterized in that: A venturi ejector (5U), a low calorific value gas branch pipe (5D), and a low calorific value gas distribution pipe (5F) are installed below the lower chamber (5S) of the regenerative flameless combustion furnace (5); the low calorific value combustible tail gas is ejected at high speed from the nozzle of the venturi ejector (5U) to generate negative pressure, and the engine tail gas flowing into the lower part of the partition (GB) through the engine tail gas downward passage (5C) is sucked, mixed with the tail gas, and rises; the mixed engine tail gas and the low calorific value gas are called mixed gas, and the mixed gas is mixed again in the lower chamber (5S) above the partition (GB) At the same time, the kinetic energy of the injected gas is converted into static pressure energy, which becomes the driving pressure for pushing the high-temperature flue gas (5E) upward; the mixed gas enters the heat storage section (5R), and while being heated by the heat storage bricks of the heat storage section (5R), the combustible components in the mixed gas meet with oxygen on the surface of the heat storage bricks to chemically burn and release heat energy, thereby achieving stable flameless combustion above the exhaust temperature of the gas turbine using the residual oxygen in the exhaust gas of the gas turbine, and while heating the heat storage bricks, the temperature of the exhaust gas of the gas turbine is increased to 800-900°C to become high-temperature flue gas.

3. The method for supplementary combustion of low calorific value combustible gas in exhaust gas of a combustion engine according to claim 1, characterized in that: A regenerative flameless combustion furnace (5) is arranged below the exhaust gas passage (2) between the exhaust gas outlet of the gas turbine (1) and the waste heat boiler (3), and a separation groove (5V) is arranged below the lower chamber (5S) of the regenerative flameless combustion furnace (5); the exhaust gas (RJWQ) of the gas turbine flowing through the exhaust gas duct (5H) and the exhaust gas descending passage (5C) of the gas turbine, and the low calorific value gas (GRZRQ) flowing through the low calorific value gas distribution pipe (5F) and the low calorific value gas branch pipe (5D) can enter the separation groove (5V) through both sides of the furnace body (5B) After passing through the partition (5V), it rises and enters the lower chamber (5S) for mixing and then enters the heat storage section (5R); the mixed gas of the engine exhaust gas and the low calorific value fuel gas is called mixed gas. While the mixed gas is heated by the heat storage bricks of the heat storage section (5R), the combustible components in the mixed gas meet with oxygen on the surface of the heat storage bricks and undergo chemical combustion to release heat energy, thereby achieving stable flameless combustion above the exhaust temperature of the engine by utilizing the residual oxygen in the engine exhaust gas of the low calorific value fuel gas, and while heating the heat storage bricks, the engine exhaust gas temperature is raised to 800-900°C to become high-temperature flue gas.

4. The method for supplementary combustion of low calorific value combustible gas in exhaust gas of a combustion engine according to claim 1, characterized in that: A regenerative flameless combustion furnace (5) is arranged below the exhaust gas passage (2) between the exhaust gas outlet of the gas turbine (1) and the waste heat boiler (3); a heat storage device providing high calorific value (calorific value ≥ 1500 kcal / Nm 3 ) a high calorific value gas distribution pipe (5L) for the gas, a high calorific value gas branch pipe (5L) and a burner (5W) are installed in the gas engine tail gas tank (RJWQC); a combustion air distribution pipe (5I) and a combustion air branch pipe (5J) are installed outside the gas engine tail gas downward passage (5C); a duct door (5G) is provided at the air inlet of the gas engine tail gas duct (5H); and a liftable smoke gate (2A) is provided at the gas engine tail gas outlet; During the shutdown period of the gas turbine, there is no exhaust gas from the gas turbine, and the duct door (5G) is closed to prevent the combustion air from flowing back into the exhaust channel (2); the flue gas gate (2A) is closed to prevent the high-temperature flue gas (5E) from flowing back into the gas turbine; the high calorific value gas is sent to the burner (5W) through the high calorific value gas distribution pipe (5L) and the high calorific value gas branch pipe (5M), and the combustion air is sent to the gas turbine exhaust tank (RJWQC) through the combustion air distribution pipe (5I) and the combustion air branch pipe (5J), and the high calorific value gas is burned on the burner (5W) in the gas turbine exhaust tank (RJWQC) through the installed electronic ignition device to form a permanent light. The low calorific value gas is sent to the low calorific value gas tank (DRZRQC) through the low calorific value gas distribution pipe (5F) and the low calorific value gas branch pipe (5D) by a fan. After the low calorific value gas rises in the tank, it mixes with the combustion-supporting air heated by the long-burning flame (5N) in the lower chamber (5S), rises, and enters the heat storage section (5R). The combustible components in the low calorific value gas meet with oxygen on the surface of the heat storage brick and chemically burn to release heat energy, thereby realizing stable flameless combustion of the low calorific value gas on the surface of the heat storage brick during the shutdown of the exhaust gas of the gas turbine. While heating the heat storage brick, the flue gas temperature rises to 800-900°C to become high-temperature flue gas.

5. The method for supplementary combustion of low calorific value combustible gas in exhaust gas of a combustion engine according to claim 1, characterized in that: A high-temperature flue gas distribution pipe (5P) with a streamlined cross section is arranged above the regenerative flameless combustion furnace (5) so that the high-temperature flue gas (5E) leaving the regenerative flameless combustion furnace can flow to the upper space of the tail gas channel (2) and be evenly mixed with the fuel gas tail gas in the upper space before entering the waste heat boiler (3) after being heated. The high-temperature flue gas distribution pipe (5P) with a streamlined cross section has the following functions:

1. reducing the occupation of the chimney on the flue flow cross section to reduce the flow resistance of the engine tail gas; 2. using the low density of the high-temperature flue gas (5E) to reduce the heat storage section (5R) and the lower chamber (5 S) so that the exhaust gas of the combustion engine enters the lower chamber (5S) of the combustion furnace and obtains the necessary pressure difference power; ③ the low-pressure areas on both sides of the streamlined high-temperature flue gas distribution pipe (5P) are provided with high-temperature flue gas outlets (5Q) along the height direction, so that part of the high-temperature flue gas (5E) flows out of the pipe during the rising process and mixes with the exhaust gas of the combustion engine at different heights, thereby heating the exhaust gas of the combustion engine at different heights to uniformly increase the temperature of the exhaust gas of the combustion engine entering the waste heat boiler; at the same time, the flow velocity of the high-temperature flue gas (5E) in the streamlined high-temperature flue gas distribution pipe (5P) is reduced along the height to reduce the flow resistance.

6. The method for supplementary combustion of low calorific value combustible gas with exhaust gas from a combustion engine according to claim 1, characterized in that: A heat exchanger (6) is arranged in the process before the low calorific value fuel gas enters the regenerative flameless combustion furnace (5); the heat exchanger is divided into three sections of high temperature, medium temperature and low temperature; the high temperature section adopts a shell and tube heat exchange method, the medium temperature section adopts a circulation to hot liquid heat exchange method, and the low temperature section adopts a heat pipe heat exchange method.

7. The method for supplementary combustion of low calorific value combustible gas in exhaust gas of a combustion engine according to claim 1, characterized in that: A heat exchanger (6) is arranged in the process before the low calorific value fuel gas enters the regenerative flameless combustion furnace (5). The heat exchanger is in the form of a fixed bed switching type regenerative heat exchanger, or a rotary type regenerative heat exchanger, or a regenerative heat exchanger of a combination of a fixed bed type and a rotary bed type, or a combination of a high temperature section with regenerative heat exchange and a low temperature section with partition wall heat exchange.

8. The method for supplementary combustion of low calorific value combustible gas with exhaust gas from a combustion engine according to claim 1, characterized in that: When the resistance of the heat exchanger (6) and its pipeline is lower than the pressure of the exhaust gas from the engine, the low-temperature exhaust gas (6B) from the engine after heat exchange is directly sent to the chimney (4) through the pipeline, and its flow rate is controlled by its valve (6C).

9. The method for supplementary combustion of low calorific value combustible gas with exhaust gas from a combustion engine according to claim 1, characterized in that: When the resistance of the heat exchanger (6) and its pipeline is higher than the exhaust pressure of the engine, the low-temperature exhaust gas (6B) of the engine is sent into the chimney (4) through the fan (C-6), and its flow rate is controlled by the fan (C-6).

10. The method for supplementary combustion of low calorific value combustible gas with exhaust gas from a combustion engine according to claim 1, characterized in that: The low calorific value fuel gas does not pass through the heat exchanger (6), but directly enters the low calorific value fuel gas distribution pipe (5F) through the low calorific value fuel gas shortcut pipe (6F).

11. The method for supplementary combustion of low calorific value combustible gas with exhaust gas from a combustion engine according to claim 1, characterized in that: The exhaust gas flow of the gas turbine is controlled by controlling the opening and closing degree of the duct door (5G), so as to adjust the exhaust gas flow of the gas turbine according to the needs of the low calorific value fuel gas flow, temperature, calorific value, and temperature of the heat storage section of the combustion furnace.

12. The method for supplementary combustion of low calorific value combustible gas with exhaust gas from a combustion engine according to claim 1, characterized in that: The combustion engine exhaust gas downward passage (5C) flowing under the partition plate (GB) is provided only on one side of the regenerative flameless combustion furnace.

13. The method for supplementary combustion of low calorific value combustible gas with exhaust gas from a combustion engine according to claim 1, characterized in that: A low calorific value fuel gas outlet pipe (5Y) and an outlet hole (5X) are arranged below the lower chamber (5S) to achieve mixing of the low calorific value fuel gas and combustion-supporting engine exhaust gas.

14. The method for supplementary combustion of low calorific value combustible gas with exhaust gas from a combustion engine according to claim 1, characterized in that: The supplementary fuel entering the regenerative flameless combustion furnace is a combustible liquid or a combustible powder. Its chemical combustion heat is converted into physical sensible heat higher than the temperature of the engine exhaust gas under the conditions of the engine exhaust gas temperature and oxygen concentration.

15. A method for supplementing combustion of low calorific value combustible gas with exhaust gas from a combustion engine, characterized in that: The combustible components of the supplementary fuel entering the regenerative flameless combustion furnace come from the induced gas from coal gasification, flash exhaust gas, vented air from the degassing tank, low-temperature methanol washing tail gas, PSA tail gas, coal gas water expansion gas, phenol-ammonia recovery deacidification tower acid gas, volatile organic compounds (VOCs) emitted from the breathing valve of the tank in the tank area, liquid nitrogen washing tail gas, and product synthesis tail gas.

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