Waste mash and slurry blending combustion system of circulating fluidized bed boiler with lignin residues as fuel

Abstract

The utility model discloses a waste mash and slurry blending combustion system of a circulating fluidized bed boiler with lignin residues as fuel. An effective treatment and utilization way is explored for harmless combustion treatment of waste mash and slurry. Aiming at the characteristics that the circulating fluidized bed boiler takes lignin residues as fuel and high-concentration waste mash slurry needs to be mixed and combusted in a hearth for combusting the lignin residues, the ignition sequence of the circulating fluidized bed boiler, the opportunity for adding the mixed-combusted waste mash slurry into the hearth and the control of the doping amount are explored through a plurality of tests; meanwhile, a blending combustion conveying system suitable for blending combustion of waste mash thick slurry is designed, and high-efficiency combustion of harmful substances in the hearth is achieved through effective regulation and control of the screw pump.

Description

Technical Field

[0001] The present invention relates to a circulating fluidized bed boiler using lignin residue as fuel, and particularly to a waste mash thick slurry co-firing system of a circulating fluidized bed boiler using lignin residue as fuel. Background Art

[0002] With the rapid development of biomass energy technology, the process of producing cellulose fuel ethanol from straw raw materials has become increasingly mature. The waste mash slurry generated after producing fuel ethanol from straw is a high-concentration organic wastewater, which has a pungent odor and corrosiveness. Once it enters natural water bodies, it will damage the ecological balance of the water bodies, cause water quality deterioration, and pollute the surrounding environment. The existing technology is to press the waste mash slurry into lignin residue through a plate and frame mechanism, and then distill and concentrate the filtrate into a thick slurry of waste mash slurry. In order to harmlessly treat the waste mash slurry generated from producing fuel ethanol from straw, boiler manufacturers have developed a circulating fluidized bed boiler using lignin residue as fuel. This kind of boiler uses lignin residue as fuel and is supplemented by co-firing concentrated waste mash slurry to achieve the combustion treatment of harmful substances. During the combustion process of the circulating fluidized bed using lignin residue as fuel, the concentrated waste mash slurry is sprayed into the burning furnace through a spray gun to achieve the co-firing of the concentrated waste mash slurry. Since the temperature in the furnace is as high as more than 600 degrees Celsius and the concentration of the concentrated waste mash slurry is also relatively high, how to make the waste mash slurry sprayed into the furnace generate an atomized form that is easy to burn, and overcome the defect that the nozzle is easily carbonized at high temperatures, resulting in nozzle blockage, has become a technical problem that needs to be solved on site. In particular, how to achieve the co-firing of the waste mash thick slurry in the circulating fluidized bed boiler and cleanly treat the harmful pollutants through the boiler combustion method has become an urgent problem that needs to be solved on site. Summary of the Invention

[0003] The present invention provides a waste mash slurry co-firing system for a circulating fluidized bed boiler using lignin residue as fuel, and explores an effective way for the harmless combustion treatment and utilization of waste mash slurry.

[0004] The present invention solves the above technical problems through the following technical solutions:

[0005] The general idea of the present invention: Aiming at the characteristics that the circulating fluidized bed boiler uses lignin residue as fuel and high-concentration waste mash slurry needs to be co-fired in the furnace for burning lignin residue, the present invention has explored the ignition sequence of the circulating fluidized bed boiler, the timing of adding the co-fired waste mash slurry into the furnace, and the control of the incorporation amount through several experiments. At the same time, a co-firing conveying system suitable for co-firing waste mash thick slurry is designed, and through the effective regulation of the screw pump, the high-efficiency combustion of harmful substances in the furnace is achieved.

[0006] A waste mash slurry co-firing system for a circulating fluidized bed boiler with lignin residue as fuel, comprising a thick slurry tank, a spray gun barrel and the furnace of the circulating fluidized bed boiler. There is waste mash thick slurry in the thick slurry tank. A secondary air furnace air inlet is arranged on the furnace of the circulating fluidized bed boiler. The fuel of the circulating fluidized bed boiler is lignin residue. A spray gun barrel is arranged on the secondary air furnace air inlet. The nozzle of the spray gun barrel is inserted into the furnace of the circulating fluidized bed boiler. A compressed air access pipe and a thick slurry access pipe are respectively connected to the tail end of the spray gun barrel. The compressed air access pipe is communicated with the compressed air input pipeline through a compressed air access hose; the thick slurry access pipe is communicated with the thick slurry supply branch pipe through a thick slurry access hose. The other end of the thick slurry supply branch pipe is communicated with the thick slurry supply main pipeline through a first stop valve. The other end of the thick slurry supply main pipeline is communicated with the thick slurry tank. A screw pump is arranged on the thick slurry supply main pipeline.

[0007] The spray gun barrel is fixedly connected to the secondary air furnace air inlet through a flange; a mixing chamber pipe is connected to the right port of the spray gun barrel. A compressed air access pipe is connected to the right port of the mixing chamber pipe. A thick slurry access pipe is connected to the pipe wall of the mixing chamber pipe. The central axis of the spray gun barrel, the central axis of the mixing chamber pipe and the central axis of the compressed air access pipe coincide. The central axis of the thick slurry access pipe forms a 90-degree angle with the central axis of the mixing chamber pipe; a nozzle base sleeve is connected to the left port of the spray gun barrel. An external thread is arranged on the outer side surface of the left end of the nozzle base sleeve. A nozzle conical cover is connected to the left end of the nozzle base sleeve. An internal thread is arranged on the inner side of the right end of the nozzle conical cover. The internal thread is screwed with the external thread. A cylindrical spray port is arranged at the left end of the nozzle conical cover; between the nozzle conical cover and the nozzle base sleeve, a nozzle inner atomizing conical jacket and a cylindrical swirl pad are successively arranged along the left-to-right direction. An outlet annular sleeve is connected to the left end of the nozzle inner atomizing conical jacket. The outlet annular sleeve is movably sleeved in the cylindrical spray port; a conical protrusion is arranged at the center of the left side surface of the cylindrical swirl pad. Cylindrical through holes for generating swirl are equally spaced on the concentric circumference outside the conical protrusion. The central axes of the cylindrical through holes are all inclined in the clockwise direction and form a 45-degree angle with the central axis of the cylindrical swirl pad. The central axes of the cylindrical through holes are all arranged on the same concentric circumference outside the conical protrusion.

[0008] An annular liquid storage chamber is arranged on the inner cavity side wall of the mixing chamber pipe. Liquid inlet cylindrical through holes are equally spaced in arc on a concentric circumference of the inner side wall of the annular liquid storage chamber. The central axes of the liquid inlet cylindrical through holes deviate from the central axis of the mixing chamber pipe, and the central axes of the liquid inlet cylindrical through holes are all arranged in an inclined manner in the clockwise direction; the thick slurry access pipe is communicated with the annular liquid storage chamber.

[0009] A pressure transmitter, a diaphragm pressure gauge and a steam purging pipeline are respectively arranged on the thick slurry supply branch pipeline.

[0010] Two thick slurry supply branch pipelines are connected in parallel at the outlet of the main thick slurry supply pipeline. Each thick slurry supply branch pipeline is connected to a spray gun barrel, and the spray head of each spray gun barrel is arranged in the furnace of the circulating fluidized bed boiler.

[0011] A co-firing method for a co-firing system of waste mash slurry in a fluidized bed boiler using lignin residue as fuel, characterized by including the following steps:

[0012] First step, ignite the furnace bottom material in the furnace of the circulating fluidized bed boiler through oil ignition;

[0013] Second step, when the temperature in the furnace of the circulating fluidized bed boiler reaches 400 °C, add lignin residue fuel into the furnace of the circulating fluidized bed boiler through the lignin residue feeding port;

[0014] Third step, when the temperature in the furnace of the circulating fluidized bed boiler reaches 500 °C, spray the waste mash thick slurry in the thick slurry tank into the furnace of the circulating fluidized bed boiler through the spray gun barrel. At this time, the pressure of the compressed air in the compressed air access pipe should be maintained at 0.6 - 0.8 MPa, the pressure of the waste mash slurry thick slurry transported in the thick slurry access pipe should be maintained at 0.3 - 0.4 MPa, and the amount of the waste mash slurry thick slurry transported into the furnace of the circulating fluidized bed boiler should be maintained at 1.5 - 2 tons per hour.

[0015] The concentration of the waste mash thick slurry in the thick slurry tank is 40% - 50%; a stirrer is arranged in the thick slurry tank, and a steam coil heat exchanger is arranged at the bottom of the thick slurry tank; the temperature of the steam in the steam purging pipeline is 120 °C, and the pressure of the steam is 0.8 MPa; the temperature of the compressed air in the compressed air access pipe is 75 °C.

[0016] The waste mash slurry is filtered into lignin residue through a plate and frame filter, and the filtrate is distilled and concentrated into thick slurry. The present invention uses a screw pump pipeline transportation system and a thick slurry spray gun injection system to return to the circulating fluidized bed boiler for combustion, which not only realizes the environmental protection treatment of harmful slurry but also provides energy steam. Description of the Drawings

[0017] Figure 1 is the structural schematic diagram of the present invention;

[0018] Figure 2 is the structural schematic diagram of the spray gun of the present invention;

[0019] Figure 3 is the mating relationship diagram of the spray head conical cover 8, the spray head base sleeve 6, the nozzle inner atomization conical jacket 11 and the cylindrical swirl spacer 12 of the present invention. Detailed Embodiment

[0020] The present invention will be described in detail below with reference to the drawings:

[0021] A waste mash slurry co-firing system for a circulating fluidized bed boiler using lignin residue as fuel, comprising a thick slurry tank 25, a spray gun barrel 1 and a circulating fluidized bed boiler furnace 36. There is waste mash thick slurry in the thick slurry tank 25. A secondary air furnace air inlet 24 is provided on the circulating fluidized bed boiler furnace 36. The fuel of the circulating fluidized bed boiler is lignin residue. A spray gun barrel 1 is provided on the secondary air furnace air inlet 24. The nozzle of the spray gun barrel 1 is inserted into the circulating fluidized bed boiler furnace 36. A compressed air access pipe 3 and a thick slurry access pipe 4 are respectively connected to the tail end of the spray gun barrel 1. The compressed air access pipe 3 is communicated with a compressed air input pipeline 35 through a compressed air access hose 33. The thick slurry access pipe 4 is communicated with a thick slurry supply branch pipe 28 through a thick slurry access hose 30. The other end of the thick slurry supply branch pipe 28 is communicated with a thick slurry supply main pipeline 26 through a first stop valve 29. The other end of the thick slurry supply main pipeline 26 is communicated with the thick slurry tank 25. A screw pump 27 is provided on the thick slurry supply main pipeline 26. Compressed air enters the spray gun barrel 1 through the compressed air access pipe 3 and is mixed with the waste mash slurry thick slurry from the thick slurry supply branch pipe 28, and then is sprayed into the circulating fluidized bed boiler furnace 36 through the nozzle and burned. The spraying amount is regulated by the screw pump 27.

[0022] The spray gun tube 1 is fixedly connected to the secondary air furnace inlet 24 through a flange 5; a mixing chamber tube 2 is connected to the right end of the spray gun tube 1, a compressed air inlet tube 3 is connected to the right end of the mixing chamber tube 2, and a concentrated slurry inlet tube 4 is connected to the tube wall of the mixing chamber tube 2. The central axis of the spray gun tube 1, the central axis of the mixing chamber tube 2 and the central axis of the compressed air inlet tube 3 coincide with each other, and the central axis of the concentrated slurry inlet tube 4 is 90 degrees to the central axis of the mixing chamber tube 2. This structure makes the compressed air The air becomes the mainstream medium in the cavity of the spray gun tube 1, and the waste mash slurry becomes an appendage attached to the compressed air flow; the left end of the spray gun tube 1 is connected to the nozzle base sleeve 6, and the outer surface of the left end of the nozzle base sleeve 6 is provided with an external thread 7, the left end of the nozzle base sleeve 6 is connected to the nozzle cone cover 8, and the inner side of the right end of the nozzle cone cover 8 is provided with an internal thread 9, the internal thread 9 and the external thread 7 are screwed together, and a cylindrical nozzle 10 is provided at the left end of the nozzle cone cover 8; the nozzle cone cover 8 and the nozzle base are connected. Between the sleeves 6, from left to right, there are arranged in sequence a nozzle atomizing cone jacket 11 and a cylindrical swirl pad 12, the left end of the nozzle atomizing cone jacket 11 is connected to an outlet annular sleeve 15, and the outlet annular sleeve 15 is movably sleeved in the cylindrical nozzle 10; a conical protrusion 13 is provided at the center of the left vertical surface of the cylindrical swirl pad 12, and cylindrical through holes 14 for generating swirl are evenly spaced on the concentric circle outside the conical protrusion 13, and the central axis of each cylindrical through hole 14 is along the clockwise direction. The needle direction is inclined and forms an angle of 45 degrees with the central axis of the cylindrical swirl pad 12. The central axes of each cylindrical through hole 14 are arranged on the same concentric circle outside the conical protrusion 13; the waste mash slurry concentrated by compressed air in the spray gun tube 1 generates a swirling fluid after passing through a group of cylindrical through holes 14, and is accelerated by the contraction of the atomizing conical jacket 11 in the nozzle under the guidance of the conical protrusion 13 to realize double-fluid conical atomization. Finally, it is sprayed into the furnace through the cylindrical nozzle 10 to make the droplets fully burn.

[0023] An annular liquid storage chamber 16 is provided on the inner sidewall of the inner cavity of the mixing chamber tube 2. Liquid inlet cylindrical through holes 17 are equidistantly arranged at equal angular intervals on a concentric circumference of the inner sidewall of the annular liquid storage chamber 16. The central axis of the liquid inlet cylindrical through hole 17 deviates from the central axis of the mixing chamber tube 2, and the central axes of the liquid inlet cylindrical through holes 17 are all arranged obliquely in the clockwise direction; the thick slurry access tube 4 is communicated with the annular liquid storage chamber 16; since the pressure in the annular liquid storage chamber 16 is less than the pressure in the mixing chamber tube 2, when high-speed compressed air passes through the annular liquid storage chamber 16, a negative pressure is generated on the liquid inlet cylindrical through holes 17 arranged at equal angular intervals on a concentric circumference of the inner sidewall of the annular liquid storage chamber 16, sucking the thick slurry of waste mash slurry in the annular liquid storage chamber 16 into the inner cavity of the mixing chamber tube 2. Since the central axes of the liquid inlet cylindrical through holes 17 deviate from the central axis of the mixing chamber tube 2 and the central axes of the liquid inlet cylindrical through holes 17 are all arranged obliquely in the clockwise direction, the thick slurry of waste mash slurry entering the inner cavity of the mixing chamber tube 2 enters in a swirling flow form, is conveyed to the left side of the spray gun barrel 1 under the entrainment of high-pressure gas, and while mixing with the high-pressure gas, a preliminary swirling flow transportation prototype is formed. Then, through a group of cylindrical through holes 14 on the cylindrical swirling flow cushion block 12, accelerated swirling flow is realized. Finally, after the contraction and acceleration of the atomizing conical jacket 11 in the nozzle, it is atomized and sprayed into the furnace through the cylindrical nozzle 10.

[0024] A pressure transmitter 31, a diaphragm pressure gauge 32 and a steam purging pipeline 34 are respectively arranged on the thick slurry supply branch pipeline 28; to realize the monitoring of the pressure in the thick slurry supply branch pipeline 28 and the cleaning of the spray gun barrel 1.

[0025] Two thick slurry supply branch pipelines are connected in parallel at the outlet of the thick slurry supply main pipeline 26. Each thick slurry supply branch pipeline is connected with a spray gun barrel 1, and the nozzle of each spray gun barrel 1 is arranged in the circulating fluidized bed boiler furnace 36; the two spray guns spray the thick waste mash slurry into the furnace simultaneously.

[0026] A co-firing method for a co-firing system of waste mash slurry in a fluidized bed boiler using lignin residue as fuel, characterized by including the following steps:

[0027] The first step, ignite the furnace bottom material in the circulating fluidized bed boiler furnace 36 through fuel ignition;

[0028] The second step, when the temperature in the circulating fluidized bed boiler furnace 36 reaches 400 degrees Celsius, add the lignin residue fuel into the circulating fluidized bed boiler furnace 36 through the lignin residue feed port 23;

[0029] Step 3: When the temperature in the furnace 36 of the circulating fluidized bed boiler reaches 500 °C, the waste mash thick slurry in the thick slurry tank 25 is sprayed into the furnace 36 of the circulating fluidized bed boiler through the spray gun tube 1. At this time, the pressure of the compressed air in the compressed air access pipe 3 should be maintained at 0.6 - 0.8 MPa, the pressure of the waste mash slurry thick slurry conveyed in the thick slurry access pipe 4 should be maintained at 0.3 - 0.4 MPa, and the amount of the waste mash slurry thick slurry conveyed into the furnace 36 of the circulating fluidized bed boiler should be maintained at 1.5 - 2 tons per hour.

[0030] The concentration of the waste mash thick slurry in the thick slurry tank 25 is 40% - 50%; a stirrer is provided in the thick slurry tank 25, and a steam coil heat exchanger is provided at the bottom of the thick slurry tank 25; the temperature of the steam in the steam purge pipeline 34 is 120 °C, and the pressure of the steam is 0.8 MPa; the temperature of the compressed air in the compressed air access pipe 3 is 75 °C.

[0031] The waste mash slurry (with a water content of 87% - 88%) in the process workshop enters the waste mash storage tank through a pipeline, and then is pumped to a plate and frame diaphragm filter press by a solid-liquid two-phase flow grouting pump. After pressing, the water content of the filter cake is about 45 - 55%. The filtrate after pressing is collected through a guide trough and returned to the process workshop for evaporation and concentration into thick slurry (with a water content of 40% - 50%) and enters the thick slurry tank 25. It is frequency-converted and adjusted by a screw pump 27, and after passing through the thick slurry supply main pipeline and atomized by a spray gun, it enters the boiler for efficient combustion; the system is equipped with a flow meter to monitor whether the flow rate of the thick slurry entering the furnace exceeds the rated flow rate to prevent boiler coking; the compressed air at the nozzle ensures the atomization combustion effect of the nozzle; the spray gun has a diameter of Φ32×3 (DN25) and is made of 316L. It is inserted from the secondary air port, and there is a primary hot air cooling spray gun sleeve outside. It is required to be inserted horizontally. After being atomized by compressed air, it is scattered into the material in a fan shape. When it enters the furnace and is disturbed by high-temperature flue gas, it is disrupted and burned in an atomized state.

[0032] The slurry injection starts when the furnace temperature is greater than 600 °C, and the slurry injection amount value is gradually increased. The ratio of the thick slurry to the lignin residue is 1:3; when the load decreases, the amount of the blended slurry gradually decreases. When the flow rate of the blended slurry decreases to a certain value, one spray gun is cut off, and only one spray gun is left for blended combustion. The cut-off spray gun needs to be cleaned and purged to prevent carbonization at the end; initially, the slurry injection starts conservatively at a load of more than 60%. After stable operation, gradually explore the lower limit; after each shutdown, the spray gun and the pipeline must be purged in time to prevent the thick slurry from solidifying and blocking the pipeline.

Claims

1. A waste mash slurry co-firing system for a circulating fluidized bed boiler using lignin residue as fuel, comprising a thick slurry tank (25), a spray gun barrel (1) and a circulating fluidized bed boiler furnace (36). Waste mash thick slurry is provided in the thick slurry tank (25), and a secondary air furnace air inlet (24) is provided on the circulating fluidized bed boiler furnace (36). The fuel of the circulating fluidized bed boiler is lignin residue, and it is characterized in that, A spray gun barrel (1) is arranged at the secondary air furnace inlet (24). The nozzle of the spray gun barrel (1) is inserted into the furnace (36) of the circulating fluidized bed boiler. At the tail end of the spray gun barrel (1), a compressed air access pipe (3) and a thick slurry access pipe (4) are respectively connected. The compressed air access pipe (3) is communicated with a compressed air input pipeline (35) through a compressed air access hose (33); the thick slurry access pipe (4) is communicated with a thick slurry supply branch pipe (28) through a thick slurry access hose (30). The other end of the thick slurry supply branch pipe (28) is communicated with a thick slurry supply main pipeline (26) through a first stop valve (29). The other end of the thick slurry supply main pipeline (26) is communicated with a thick slurry tank (25). A screw pump (27) is arranged on the thick slurry supply main pipeline (26).

2. The waste mash slurry co-firing system of a circulating fluidized bed boiler using lignin residue as fuel according to claim 1, characterized in that, The spray gun barrel (1) is fixedly connected to the secondary air furnace inlet (24) through a flange (5); a mixing chamber pipe (2) is connected to the right port of the spray gun barrel (1). A compressed air access pipe (3) is connected to the right port of the mixing chamber pipe (2). A thick slurry access pipe (4) is connected to the pipe wall of the mixing chamber pipe (2). The central axes of the spray gun barrel (1), the mixing chamber pipe (2), and the compressed air access pipe (3) coincide. The central axis of the thick slurry access pipe (4) forms a 90-degree angle with the central axis of the mixing chamber pipe (2); a nozzle base sleeve (6) is connected to the left port of the spray gun barrel (1). An external thread (7) is arranged on the outer side surface of the left end of the nozzle base sleeve (6). A nozzle conical cover (8) is connected to the left end of the nozzle base sleeve (6). An internal thread (9) is arranged on the inner side of the right end of the nozzle conical cover (8). The internal thread (9) is screwed with the external thread (7). A cylindrical nozzle (10) is arranged at the left end of the nozzle conical cover (8); between the nozzle conical cover (8) and the nozzle base sleeve (6), a nozzle inner atomizing conical jacket (11) and a cylindrical swirl spacer (12) are sequentially arranged in the left-to-right direction. An outlet annular sleeve (15) is connected to the left end of the nozzle inner atomizing conical jacket (11). The outlet annular sleeve (15) is movably sleeved in the cylindrical nozzle (10); a conical protrusion (13) is arranged at the center of the left side surface of the cylindrical swirl spacer (12). Cylindrical through holes (14) for generating swirl are equally spaced on the concentric circumference outside the conical protrusion (13). The central axes of the cylindrical through holes (14) are all inclined in the clockwise direction and form a 45-degree angle with the central axis of the cylindrical swirl spacer (12). The central axes of the cylindrical through holes (14) are all arranged on the same concentric circumference outside the conical protrusion (13).

3. The waste mash slurry co-firing system of a circulating fluidized bed boiler using lignin residue as fuel according to claim 2, characterized in that, An annular liquid storage chamber (16) is arranged on the side wall of the inner cavity of the mixing chamber tube (2). Liquid inlet cylindrical through holes (17) are arranged at equal angular intervals on a concentric circumference of the inner side wall of the annular liquid storage chamber (16). The central axis of each liquid inlet cylindrical through hole (17) deviates from the central axis of the mixing chamber tube (2), and the central axes of the liquid inlet cylindrical through holes (17) are all arranged obliquely in the clockwise direction. The thick slurry access pipe (4) is communicated with the annular liquid storage chamber (16).

4. A waste mash slurry co-firing system for a circulating fluidized bed boiler using lignin residue as fuel according to claim 3, characterized in that, A pressure transmitter (31), a diaphragm pressure gauge (32) and a steam purging pipeline (34) are respectively arranged on the thick slurry supply shunt pipe (28).

5. The waste mash slurry co-firing system of a circulating fluidized bed boiler using lignin residue as fuel according to claim 1, characterized in that, Two thick slurry supply branch pipelines are connected in parallel at the outlet of the thick slurry supply main pipeline (26). Each thick slurry supply branch pipeline is connected with a spray gun barrel (1), and the nozzle of each spray gun barrel (1) is arranged in the furnace (36) of the circulating fluidized bed boiler.

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