Low temperature ignition method for nanocarbon hydrocarbon fuel

Abstract

The application provides a low-temperature ignition method of nano-carbon hydrogen fuel. The method comprises the following steps: firstly, pre-ignition is carried out in a boiler by using an ignition gun, auxiliary fuel is sprayed into the oil gun by an oil supply pump, air is supplied through an air supply port, the auxiliary fuel is ignited and burned, and the hearth temperature of the boiler is heated to 180-610 DEG C; then, the nano-carbon hydrogen fuel is sprayed into the fuel spray gun by a slurry supply pump, the nano-carbon hydrogen fuel and the auxiliary fuel are mixed and burned in the hearth at low temperature; the slurry pressure in front of the burner of the boiler is controlled to be 0.4-0.6 MPa, the air supply tank pressure is controlled to be 0.6-0.7 MPa, and the air-assisted combustion time is 5-10 min; finally, after the hearth temperature is stable, the flow of the mixed auxiliary fuel is gradually reduced, and the nano-carbon hydrogen fuel is self-sustaining combustion. The application can ensure the low-temperature ignition of the nano-carbon hydrogen fuel, the stable combustion, the normal subsequent temperature rising operation, the low energy consumption and the high safety coefficient.

Description

Technical Field

[0001] The present invention relates to the technical field of environmentally friendly fuels, and in particular to a low-temperature ignition method for nano-hydrocarbon fuels. Background Art

[0002] Nanocarbon fuel is a coal-based liquid fuel with micro-nano particle size, high specific surface area and surface activity, produced using advanced nano-crushing technology and equipment through pre-treatment, refinement, nano-processing, and hydrogenation. It is a new, efficient, clean, and environmentally friendly fuel. Compared with traditional coal-water slurries, it boasts high combustion efficiency, high ash activity, and low pollutant emissions. As a new fuel, nanocarbon fuel has micro-nano particle size. Its physical and chemical properties differ significantly from those of conventional coal-based liquid fuels, such as coal-water slurries, and its combustion characteristics are also significantly different from those of conventional coal-water slurries.

[0003] Patent CN 114002370 A discloses a system and method for testing the combustion performance of nanocarbon fuels. This system uses fuel oil and air to ignite the nanocarbon fuels. However, the ignition temperature is relatively high (850-1200°C), resulting in high energy consumption and a low safety factor during the actual ignition process. Currently, no suitable low-temperature ignition method for nanocarbon fuels exists. Summary of the Invention

[0004] The main purpose of the present invention is to provide a low-temperature ignition method for nano-hydrocarbon fuel, so as to solve the problem that there is no low-energy consumption, high-safety low-temperature ignition method suitable for nano-hydrocarbon fuel in the prior art.

[0005] To achieve the above-mentioned object, according to one aspect of the present invention, a low-temperature ignition method for nano-hydrocarbon fuel is provided, comprising the following steps: step S1, in a boiler, pre-ignition is performed using an ignition gun, auxiliary fuel is pumped into the oil gun via an oil supply pump, air is supplied through an air supply port, and the auxiliary fuel is ignited and burned, so that the furnace temperature of the boiler is heated to 180-610°C; step S2, nano-hydrocarbon fuel is pumped into the fuel spray gun via a slurry supply pump, and the nano-hydrocarbon fuel and the auxiliary fuel are ignited and mixed in the furnace at low temperature; the slurry pressure before the burner of the boiler is controlled to be 0.4-0.6 MPa, the pressure of the air supply tank is controlled to be 0.6-0.7 MPa, and the air-combustion time is controlled to be 5-10 minutes; step S3, after the furnace temperature stabilizes, the flow rate of the auxiliary fuel is gradually reduced until the nano-hydrocarbon fuel self-sustains combustion.

[0006] Furthermore, in step S1, the auxiliary fuel is one or more of diesel, heavy oil and natural gas, and the oil supply pressure of the oil supply pump is 0.4 to 0.6 MPa: Preferably, before pre-ignition, step S1 also includes the step of using a blower and an induced draft fan to purge the boiler; more preferably, the frequency of the blower is 8 to 12 Hz, the frequency of the induced draft fan is 18 to 22 Hz, the furnace negative pressure is -10 to -25 Pa, and the purge time is 8 to 12 minutes.

[0007] Furthermore, when pre-ignition is unsuccessful, the ignition gun is turned off, and the purge step is repeated before pre-ignition is performed; when pre-ignition is successful, the ignition gun is withdrawn, and the frequency of the blower and induced draft fan is adjusted to maintain the oxygen content of the furnace flue gas at 10-12%.

[0008] Furthermore, in step S1, during the rising process of the furnace temperature, a cooling system is used for temperature control, and the cooling system includes a boiler circulating water pump and a cooling circulating water pump; preferably, the operating frequency of the cooling system is adjusted so that the boiler circulating water temperature is ≤75°C.

[0009] Furthermore, in step S2, the frequency of the slurry supply pump is controlled to be 8-12 Hz. After the nano-hydrocarbon fuel reflux occurs, the frequency of the slurry supply pump is controlled to be 18-22 Hz to perform low-temperature ignition and mixing.

[0010] Furthermore, in step S3, after the furnace temperature is stabilized, the oxygen content of the furnace flue gas is 9-11%.

[0011] Furthermore, in step S3, the oil supply pressure of the oil supply pump is controlled to be 0.25-0.35 MPa to gradually reduce the flow rate of the auxiliary fuel for blending.

[0012] Furthermore, in step S3, the oxygen content of the flue gas in the furnace is controlled to be 8-13% to enable the nano-hydrocarbon fuel to self-sustain combustion.

[0013] Furthermore, after step S3, the low-temperature ignition method further includes: stopping feeding the nano-hydrocarbon fuel, and stopping air supply when the furnace temperature drops below 350°C; and stopping the cooling system and allowing natural cooling when the furnace temperature drops below 150°C.

[0014] Furthermore, the mass concentration of the nano-hydrocarbon fuel is 20-60%.

[0015] The application of the technical solution of the present invention can well ensure the successful low-temperature ignition of nano-hydrocarbon fuel, stable combustion, and ensure the subsequent normal temperature rise operation, with low energy consumption and high safety factor. DETAILED DESCRIPTION

[0016] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0017] It should be noted that the low-temperature ignition method of the present invention can be performed using a conventional boiler system or using the nano-hydrocarbon fuel combustion performance test system in Chinese patent CN 114002370A.

[0018] Explanation of terms:

[0019] Oxygen content: refers to the weight percentage of oxygen in the boiler furnace, which can indirectly characterize the combustion state of nano-hydrocarbon fuel. The higher the oxygen content, the more incomplete the combustion.

[0020] As described in the background of the present invention, there is a problem in the prior art that there is no low-energy consumption, high-safety low-temperature ignition method suitable for nano-hydrocarbon fuel. In order to solve the above problem, in a typical embodiment of the present invention, a low-temperature ignition method for nano-hydrocarbon fuel is provided, comprising the following steps: step S1, in a boiler, using an ignition gun for pre-ignition, pumping auxiliary fuel into the oil gun through an oil supply pump, supplying air through an air supply port, igniting and burning the auxiliary fuel, so that the furnace temperature is heated to 180-610°C; step S2, pumping nano-hydrocarbon fuel into the fuel spray gun through a slurry supply pump, and igniting and mixing the nano-hydrocarbon fuel and the auxiliary fuel in the furnace at low temperature; controlling the slurry pressure before the burner of the boiler to 0.4-0.6MPa, the pressure of the air supply tank to 0.6-0.7MPa, and the air-combustion time to 5-10min; step S3, after the furnace temperature stabilizes, gradually reducing the flow rate of the auxiliary fuel to be mixed until the nano-hydrocarbon fuel self-sustains combustion.

[0021] The present invention first uses an ignition gun to perform pre-ignition in the boiler, injects auxiliary fuel into the oil gun, supplies air to assist combustion, and ignites and burns the auxiliary fuel to heat the furnace temperature to a low temperature of 180-610°C; then injects nanocarbon fuel into the fuel spray gun, and the nanocarbon fuel and the auxiliary fuel are ignited and mixed in the furnace at a low temperature. During this process, the boiler's burner front slurry pressure is controlled to be 0.4-0.6MPa, the air supply tank pressure is 0.6-0.7MPa, and the air burning time is 5-10min to maintain a stable combustion state. When the nanocarbon fuel is ignited at a low temperature, the air supply can be divided into primary air and secondary air according to actual needs. The primary air volume can be reduced according to the on-site situation to quickly evaporate the water content of the nanocarbon fuel, increase the secondary air volume, and meet the oxygen demand for the combustion of the nanocarbon fuel. Finally, after the furnace temperature stabilizes, the flow rate of the auxiliary fuel mixed is gradually reduced until the nanocarbon fuel self-sustains combustion and ignites successfully.

[0022] The method of the present invention can well ensure the successful low-temperature ignition of nano-hydrocarbon fuel and stable combustion, can ensure the subsequent normal temperature rise operation, has low energy consumption, high safety factor, and is more in line with production practice.

[0023] In a preferred embodiment, in step S1, the auxiliary fuel is one or more of diesel, heavy oil and natural gas, the oil supply pressure of the oil pump is 0.4~0.6MPa, and the oil gun atomization effect is better: preferably, before pre-ignition, step S1 also includes the step of using a blower and an induced draft fan to purge the boiler; more preferably, the frequency of the blower is 8~12Hz, the frequency of the induced draft fan is 18~22Hz, the furnace negative pressure is -10~-25pa, and the purge time is 8~12min, so as to further remove residues in the boiler, avoid deflagration, better ensure equipment safety, and further reduce costs.

[0024] Specifically, in a preferred embodiment, when pre-ignition is unsuccessful, the ignition gun is turned off, and the purge step is repeated before pre-ignition is performed; when pre-ignition is successful, the ignition gun is withdrawn, and the frequency of the blower and the induced draft fan is adjusted to maintain the oxygen content of the furnace flue gas at 10-12%, which can further ensure that the auxiliary fuel in the furnace is fully burned and the flame is more stable. When nano-hydrocarbon fuel is ignited at low temperature, the oil gun co-firing time should be appropriately extended. However, the "oil slurry competes for oxygen" phenomenon is prone to occur during oil gun co-firing, and the oil gun output should be appropriately reduced, and the oil should be decisively withdrawn when the furnace temperature rises rapidly. If the furnace temperature increases slowly, close attention should be paid to changes in the oxygen content. If "the oxygen content increases and the negative pressure in the furnace increases", the slurry should be cut off in time to prevent the accumulation of combustibles.

[0025] In a preferred embodiment, in step S1, during the rising process of the furnace temperature, a cooling system is used for temperature control. The cooling system includes a boiler circulating water pump and a cooling circulating water pump, which makes temperature control easier. Preferably, the operating frequency of the cooling system is adjusted so that the boiler circulating water temperature is ≤75°C, which can dissipate heat from the boiler faster and make it easier to control the heating rate of the boiler.

[0026] To further ensure the stability of the reflux of the nano-hydrocarbon fuel, in a preferred embodiment, in step S2, the frequency of the slurry pump is controlled to 8-12 Hz. After the reflux of the nano-hydrocarbon fuel occurs, the frequency of the slurry pump is controlled to 18-22 Hz to perform low-temperature ignition and blending.

[0027] In a preferred embodiment, in step S3, after the furnace temperature is stabilized, the oxygen content of the furnace flue gas is 9-11%, which can further ensure the stable ignition of the nano-hydrocarbon fuel.

[0028] During the specific operation, in a preferred embodiment, in step S3, the oil supply pressure of the oil supply pump is controlled to be 0.25-0.35 MPa, so as to gradually reduce the flow rate of the auxiliary fuel to be blended and burnt, thereby achieving the oil withdrawal operation.

[0029] In a preferred embodiment, in step S3, the oxygen content of the furnace flue gas is controlled to be 8-13% to enable the nano-hydrocarbon fuel to stably and self-sustainably burn, further ensuring the safe and stable operation of the ignition system.

[0030] After low-temperature ignition and combustion are completed, in a preferred embodiment, after step S3, the low-temperature ignition method further includes: stopping the introduction of nano-hydrocarbon fuel, and when the furnace temperature drops below 350°C, stopping the air supply to achieve faster cooling. When the furnace temperature drops below 150°C, stopping the cooling system to allow natural cooling can further prevent the desalted water in the water cooling pipe from vaporizing after the pump is stopped, which could damage the boiler body.

[0031] In a preferred embodiment, the mass concentration of the nano-hydrocarbon fuel is 20-60%, which is more in line with production practice and has a wider range of applications.

[0032] The present application is further described in detail below with reference to specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in this application.

[0033] Example 1

[0034] 1. Preparation before ignition

[0035] (1) Check that the boiler fire door is closed, the explosion-proof door operates normally, the fire inspection observation hole is free of stains, the primary and secondary air regulating valves are flexible, and the liquid level of the boiler expansion tank is normal and within the range of 300-350mm;

[0036] (2) Check that the valves and switches of the boiler circulating water system and the cooling circulating water system are in the correct position, and that the circulating water pump is tested at 5Hz and operates normally, and the flow rate display is normal;

[0037] (3) Check that the cooling tower water supply is normal and start the cooling tower fan; the compressed air pressure and flow are normal;

[0038] (4) Check that the valves of the platform slurry supply system are switched correctly and that the stirring device is operating normally.

[0039] 2. Ignition operation

[0040] (1) Start the blower and induced draft fan to purge the boiler. The blower frequency is set to 10 Hz, the induced draft fan frequency is 20 Hz, the furnace negative pressure is controlled at -15 Pa, and the purge time is 10 minutes;

[0041] (2) Start the boiler circulating water pump, heat exchanger circulating pump, and cooling tower fan, and observe for 1 minute after the flow rate stabilizes to confirm that the circulating cooling system is operating normally;

[0042] (3) Before starting the fuel supply pump (diesel pump), open the return valve of the diesel tank to prevent excessive pressure from damaging the diesel pump during startup. Adjust the opening of the return valve to keep the fuel supply pressure at 0.5MPa to ensure the atomization effect of the oil gun.

[0043] (4) Check and clean the fuel injection nozzle to ensure that the fuel gun atomization is normal.

[0044] (5) After the two oil guns (No. 1 and No. 2) are installed in place, ignition is performed. The DCS system (distributed control system) controls the ignition gun and the oil gun. First, turn on the ignition gun. After the ignition gun operates normally, open the fuel injection valve and perform fuel injection ignition. Observe the fire situation in time through the scene and video.

[0045] 1) If ignition fails, immediately close the oil valve, purge the boiler again, check the ignition system, and ignite again after eliminating any problems.

[0046] 2) If the ignition is successful, remove the ignition gun in time, pay attention to the ignition stability, adjust the fuel pump pressure to ensure the atomization effect of the diesel entering the furnace, and adjust the blower and induced draft fan frequency to ensure sufficient and stable combustion of the diesel entering the furnace.

[0047] 3. Boiler heating

[0048] (1) The boiler is ignited normally, and after adjusting the blower and induced draft fan frequencies, the oxygen content in the flue gas is detected to be 11%, ensuring that the diesel in the furnace is fully burned and the flame is stable.

[0049] (2) During the boiler heating process, always pay attention to the boiler circulating water temperature and circulating cooling water temperature. The maximum boiler circulating water temperature should not exceed 75℃.

[0050] (3) Control the temperature of the circulating water in the furnace by adjusting the operating frequency of the boiler circulating water pump and the cooling circulating water pump. At the same time, pay more attention to the cooling water replenishment.

[0051] (4) During the boiler heating process, the heating rate can be reduced by removing an oil gun. The furnace temperature can be controlled to a certain extent by controlling the boiler circulating water flow and induced draft volume. Increasing the circulating water flow and increasing the induced draft fan frequency can dissipate heat from the boiler faster and slow down the boiler heating rate to a certain extent.

[0052] (5) During the operation of the boiler, it is necessary to always pay attention to the inlet temperature of the bag filter, which should not exceed 180°C to avoid damaging the bags.

[0053] (6) Maintain the stability of various index parameters, and all temperature measuring points in the furnace tend to be stable. After the overall temperature reaches the set ignition temperature of 610℃, the temperature rise is completed and the conditions for slurry casting are met.

[0054] 4. Slurry casting and ignition

[0055] When the furnace temperature rises to the set ignition temperature of 610°C, prepare to add nano-hydrocarbon fuel slurry (50wt%). Open the inlet and outlet valves of the slurry pump and filter, open the slurry pump outlet return valve, turn on the slurry pump and filter, confirm normal operation, set the slurry pump frequency to 10Hz, and observe whether there is backflow. Gradually increase the slurry pump operating frequency to 20Hz to ensure stable backflow. Adjust the slurry pressure before the burner to about 0.5MPa, maintain the air supply tank pressure at 0.65MPa, and burn for 8 minutes. The oil-slurry mixed combustion is stable.

[0056] 5. Oil withdrawal operations

[0057] (1) Manually remove the No. 2 oil gun.

[0058] (2) Observe that the oxygen content is maintained at about 10%, confirm that the coal slurry has been stably ignited and the furnace temperature is stable.

[0059] (3) Slowly open the diesel return valve, reduce the pressure in the fuel supply pipeline to 0.3 MPa, and reduce the fuel injection volume of the No. 1 fuel gun.

[0060] (4) Observe the combustion in the furnace and check whether the flame is bright.

[0061] (5) Remove the No. 1 oil gun.

[0062] (6) Manually close the main oil valve and stop the oil pump.

[0063] (7) During the oil removal process, attention should be paid to the ignition of the coal slurry and the changes in the furnace temperature. If the ignition condition deteriorates or the furnace temperature tends to decrease, the oil removal operation should be stopped.

[0064] (8) After the oil is removed, if the ignition condition of the coal slurry worsens and there is a possibility of flameout, the slurry supply should be stopped immediately and the slurry gun should be removed.

[0065] 6. Stable combustion of coal-based nanocarbon fuel

[0066] (1) After the oil gun is removed, the coal-based nano-hydrocarbon fuel burns stably. The temperature changes at each temperature measuring point are observed to determine whether it is ignited.

[0067] (2) Pay attention to the slurry pump frequency, slurry supply pressure, blower frequency, induced draft fan frequency, boiler circulating water inlet and outlet temperature, cooling circulating water inlet and outlet temperature. The bag filter inlet temperature should not exceed 180℃. The overall system is required to operate stably.

[0068] (3) During the combustion process, according to the fuel combustion situation, timely adjust the frequency of the slurry pump, blower, and induced draft fan to maintain the operating oxygen content at 10%; at the same time, pay close attention to the changes in the furnace temperature, boiler circulating water, bag filter inlet temperature, etc., and make timely adjustments to ensure safe and stable platform operation.

[0069] 7. Remove slurry and stop the furnace

[0070] (1) After the test, close the slurry inlet three-way valve and the slurry begins to flow back; at the same time, pull out the slurry gun, cool it down and clean it thoroughly, and clean the slurry supply pipeline at the same time.

[0071] (2) After stopping the fuel supply, the furnace temperature begins to drop. Since the furnace has good thermal insulation performance, the overall cooling process is relatively smooth. It is necessary to continue to keep the boiler circulating water pump and the cooling circulating water pump running to prevent the desalted water in the water cooling pipe from vaporizing after stopping the pump, which may cause damage to the boiler body.

[0072] (3) When the furnace temperature drops below 350°C, stop the blower and induced draft fan.

[0073] (4) When the overall furnace temperature drops below 150°C, stop the boiler circulating water pump and cooling circulating water pump and allow natural cooling.

[0074] (5) After the test, check and confirm the system, close the cooling water valve to prevent water leakage, open the ash discharger to clean the ash residue generated during the experiment, open the bag dust collector ash discharge valve to carry out ash cleaning operations.

[0075] The furnace temperature data at different measuring points during the ignition process are shown in Table 1. It can be seen that when the furnace temperature rose to 610°C, the addition of nano-hydrocarbon fuel successfully ignited the furnace, and the furnace temperature rose steadily. Subsequently, the auxiliary fuel oil was gradually removed, and the furnace temperature fluctuated slightly before beginning to rise and gradually stabilizing. The nano-hydrocarbon fuel was able to maintain stable combustion.

[0076] Example 2

[0077] The difference from Example 1 is that a 51% mass concentration of nanocarbon fuel was used, and the ignition temperature was set at 436°C. The furnace temperature data during the ignition process are shown in Table 2. It can be seen that with a raw coal calorific value of 4000 kcal, the 51% mass concentration of nanocarbon fuel slurry successfully ignited at a furnace temperature of 436°C, and stable combustion was achieved after the oil was removed. The flame was golden yellow, with a clear outline and stable flame. The oxygen content decreased from 15.3% to 11.9%, and the furnace pressure was stable, achieving stable combustion.

[0078] Example 3

[0079] The difference from Example 1 is that a 50.6% mass concentration of nanocarbon fuel was used, and the ignition temperature was set at 288°C. The furnace temperature data during the ignition process are shown in Table 3. As can be seen, with a raw coal with a calorific value of 4000 kcal and a 50.6% mass concentration of nanocarbon fuel, low-temperature ignition at a furnace temperature of 288°C was successful on the test platform, and stable combustion was achieved after the oil was removed. The flame stabilized when its color gradually changed from dark red to yellow; the oxygen content decreased from 14.8% to 12.4%; and the furnace pressure remained stable, indicating stable combustion.

[0080] Example 4

[0081] The difference from Example 1 is that a 49.8% mass concentration of nanocarbon fuel was used, and the ignition temperature was set at 200°C. The furnace temperature data during the ignition process are shown in Table 4. This shows that with a raw coal calorific value of 4000 kcal and a 49.8% mass concentration of nanocarbon fuel, low-temperature ignition at a furnace temperature of 200°C was achieved on the test platform, and stable combustion was achieved after the oil was removed.

[0082] Example 5

[0083] The difference from Example 1 is that a 50% mass concentration of nanocarbon fuel was used, and the ignition temperature was set at 180°C. The furnace temperature data during the ignition process are shown in Table 5. This shows that with a raw coal calorific value of 4000 kcal and a 50% mass concentration of nanocarbon fuel, low-temperature ignition at a furnace temperature of 180°C can be achieved on the test platform, and stable combustion can be achieved after the oil is removed.

[0084] Table 1

[0085] Working conditions ℃ Measuring point A Measuring point B Measuring point C Measuring point D Measuring point E Measuring point F Measuring point G Measuring point H Measuring point I Measuring point J When ignited 78.93 97.31 88.6 75.71 57.86 57.64 57.71 64.57 55.66 58.32 Fuel 115.06 219.24 238.26 281.59 223.05 227.93 246.97 355.99 248.19 298.66 When feeding 610.45 592.51 586.99 582.91 581.72 503.52 524.32 601.13 432.99 438.26 When withdrawing oil 608.26 616.85 599.52 577.18 586.31 515.77 546.51 607.11 446.12 464.51 When pulping stops 617.24 638.05 628.72 642.31 635.31 525.39 564.92 652.11 468.19 481.79

[0086] Table 2

[0087] Working conditions ℃ Measuring point A Measuring point B Measuring point C Measuring point D Measuring point E Measuring point F Measuring point G Measuring point H Measuring point I Measuring point J When ignited 30.98 25.58 31.59 33.17 25.58 31.86 31.9 26.31 31.13 28.78 Fuel 117.18 220.24 103.12 201.19 196.65 109.91 175.24 179.98 73.04 145.65 When feeding 310.79 425.39 318.19 428.13 436.53 307.86 435.26 423.51 207.18 319.24 When withdrawing oil 325.17 463.26 359.18 443.58 460.79 332.98 492.15 440.99 223.7 359.38 When pulping stops 390.26 478.18 428.52 454.64 471.39 381.98 539.26 507.99 307.11 431.18

[0088] Table 3

[0089] Working conditions ℃ Measuring point A Measuring point B Measuring point C Measuring point D Measuring point E Measuring point F Measuring point G Measuring point H Measuring point I Measuring point J When ignited 55.51 73.73 56.78 60.37 49.51 44.04 48.38 55.32 47.77 36.59 When feeding 128.59 271.12 288.52 172.73 163.53 153.78 178.91 203.05 140.06 154.86 Oil-slurry mixed firing 133.05 278.32 296.51 178.71 169.51 159.72 191.31 209.45 146.51 161.59 When withdrawing oil 141.26 289.45 306.06 192.04 180.78 174.51 207.18 227.44 162.91 180.98 When pulping stops 145.51 290.45 308.25 200.05 185.92 180.44 211.65 235.37 169.77 185.11

[0090] Table 4

[0091] Working conditions ℃ Measuring point A Measuring point B Measuring point C Measuring point D Measuring point E Measuring point F Measuring point G Measuring point H Measuring point I Measuring point J When ignited 32.52 30.32 35.37 36.72 28.39 33.25 35.52 30.66 33.91 36.79 When feeding 99.04 201.1 165.3 131.0 126.9 112.5 148.1 170.5 60.3 124.9 When withdrawing oil 104.9 211.1 176.1 140.2 146.4 120.7 176.3 193.5 64.84 134.1 When pulping stops 131.7 235.5 185.1 178.5 165.8 150.1 198.4 220.9 90.38 159.4

[0092] Table 5

[0093] Working conditions ℃ Measuring point A Measuring point B Measuring point C Measuring point D Measuring point E Measuring point F Measuring point G Measuring point H Measuring point I Measuring point J When ignited 32.71 31.32 34.91 35.91 27.46 32.59 34.05 30.05 32.25 27.71 When feeding 85.37 180.2 146.8 114.5 111.5 98.92 131.9 152.9 54.32 113.5 When withdrawing oil 91.78 189.7 156.3 122.7 119.1 105.2 140.2 161.8 57.2 119.3 When pulping stops 122.4 230.3 188.7 164.2 157.5 143.1 187.5 208.1 78.59 153.1

[0094] As can be seen from the above, the present invention can well ensure the successful low-temperature ignition of nano-hydrocarbon fuel, stable combustion, and subsequent normal temperature rise operation, with low energy consumption and high safety factor.

[0095] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A low-temperature ignition method for nano-hydrocarbon fuel, characterized in that: The following steps are involved: Step S1: Pre-ignition is performed in the boiler using an ignition gun. Auxiliary fuel is pumped into the oil gun via an oil supply pump, and air is supplied through an air supply port to ignite and burn the auxiliary fuel, thereby heating the furnace temperature of the boiler to 180-610°C. Step S2: pumping the nano-hydrocarbon fuel into the fuel spray gun through the slurry supply pump, igniting and burning the nano-hydrocarbon fuel and the auxiliary fuel at low temperature in the furnace; controlling the slurry pressure before the burner of the boiler to 0.4-0.6 MPa, the pressure of the air supply tank to 0.6-0.7 MPa, and the air-assisted combustion time to 5-10 minutes; Step S3, after the furnace temperature stabilizes, gradually reducing the flow rate of the auxiliary fuel until the nano-hydrocarbon fuel self-sustains combustion; In step S1, the auxiliary fuel is one or more of diesel, heavy oil and natural gas, and the oil supply pressure of the oil supply pump is 0.4-0.6 MPa; In step S2, the frequency of the slurry supply pump is controlled to 8-12 Hz, and after the nano-hydrocarbon fuel reflux occurs, the frequency of the slurry supply pump is controlled to 18-22 Hz to perform the low-temperature ignition and blending; In step S3, the oil supply pressure of the oil supply pump is controlled to be 0.25-0.35 MPa to gradually reduce the flow rate of the auxiliary fuel for blending.

2. The low temperature ignition method according to claim 1, characterized in that: Before the pre-ignition, the step S1 further includes the step of using a blower and an induced draft fan to purge the boiler.

3. The low temperature ignition method according to claim 2, characterized in that: The frequency of the blower is 8~12Hz, the frequency of the induced draft fan is 18~22Hz, the furnace negative pressure is -10~-25Pa, and the purge time is 8~12min.

4. The low temperature ignition method according to claim 2, characterized in that: When the pre-ignition is unsuccessful, turning off the ignition gun, repeating the purge step, and then performing the pre-ignition; When the pre-ignition is successful, the ignition gun is withdrawn, and the frequencies of the blower and the induced draft fan are adjusted to maintain the oxygen content of the furnace flue gas at 10-12%.

5. The low temperature ignition method according to any one of claims 1 to 4, characterized in that: In the step S1, during the rising process of the furnace temperature, a cooling system is used to control the temperature, and the cooling system includes a boiler circulating water pump and a cooling circulating water pump.

6. The low temperature ignition method according to claim 5, characterized in that: The operating frequency of the cooling system is adjusted so that the boiler circulating water temperature is ≤75°C.

7. The low temperature ignition method according to any one of claims 1 to 4, characterized in that: In step S3, after the furnace temperature is stabilized, the oxygen content of the furnace flue gas is 9-11%.

8. The low temperature ignition method according to any one of claims 1 to 4, characterized in that: In step S3, the oxygen content of the furnace flue gas is controlled to be 8-13% to enable the nano-hydrocarbon fuel to self-sustain combustion.

9. The low temperature ignition method according to claim 5, characterized in that: After step S3, the low-temperature ignition method further includes: stopping the feeding of the nano-hydrocarbon fuel, and stopping the air supply when the furnace temperature drops below 350° C.; and stopping the cooling system and allowing natural cooling when the furnace temperature drops below 150° C.

10. The low temperature ignition method according to any one of claims 1 to 4, characterized in that: The mass concentration of the nano-hydrocarbon fuel is 20-60%.