RU2096688C1 - Boiler oilless starting system - Google Patents

Abstract

FIELD: thermal power stations. SUBSTANCE: system has main and additional lines for pulverized fuel feed from bin 1 to boiler starting burner 5. Additional line 9 has rated-length heat treatment section 10 in the form of vertical loop with transfer gas duct 11 and gate valve 12 to control pulverized fuel residence time in hot-gas zone, these gases being additionally heated in additional heater 13 mounted at inlet of line 9. Throttling device 16 in the form of contracted duct of rated sectional area preventing fire jump from burner 5 to heat treatment section is installed at outlet of line 10. Preignition chamber 14 is installed upstream of burner 5 and connected to throttling device. Burner incorporates flame sensors 18 connected through actuator to pulverized fuel feeders 2, 3. Crossover tube 15 connecting pre-combustion chamber 14 to burner 5 houses electric ignition device 8. EFFECT: improved design. 1 dwg

Description

 The invention relates to a power system and can be used in thermal power plants for kindling a boiler.

 The known scheme of boiler dust preparation (D. M. Khzmalyan, Ya. A. Kagan. "Energy" Moscow, 1976, p. 291, Fig. 14 4b) containing a dust bin with a dust collector and a dust supply line to the boiler burner connected to hot air lines.

 A disadvantage of the known scheme is the lack of heat treatment of fuel before burning, which complicates the process of kindling and burning of dust, since when dust enters the furnace, this process occurs in the volume of the furnace, which reduces its volume for combustion, and the afterburning is delayed to convective surfaces.

 The known scheme of the boiler kindling dust system (Journal of Electric Stations N 10, 1991, p. 40 42. article "The kindling chamber vacuum systems of steam boilers" N. Seulin and others), containing the kindling dust bin with dust, connected to the boiler burner by a line supply of dust connected to hot air.

 A disadvantage of the known scheme is the lack of heat treatment of dust to a kindling burner, which complicates the ignition process and destabilizes combustion.

 There is a known scheme of oil-free kindling of a boiler (Felker A.A. Pronin M.S. et al. About oil-free kindling of steam boilers burning Kansk-Achinsk drill coals. Magazine "Teploenergetika", 1991, N 3, p. 22 25, Fig. 2 , 3) containing a kindling dust bin, dust collectors, a line for supplying dust to a kindling burner of a boiler furnace connected to a hot air line, and an electric firing device installed in a kindling burner.

 A disadvantage of the known scheme is the unreliability of ignition due to the lack of emission of the required amount of hot gases or dust at the time of its contact with the hot surface of the electro-filling device in view of the short time, contact, which is hundredths of a second.

 The objective of the invention is to increase the reliability of dust ignition during the kindling of the boiler and reduce energy consumption in this case due to the combustion of hot gases formed during thermal decomposition of dust to a kindling burner.

 The problem is solved in that in the oil-free kindling circuit of the boiler, comprising a kindling dust bin with dust collectors, a dust supply line to the boiler ignition burner connected to a hot air line, and an electroslave device according to the invention, an additional thermal line is placed between the ignition dust bin and the ignition burner dust decomposition, including the heat treatment area of the calculated length in the form of a vertical loop with a bypass duct and a gate, communicating at the inlet with a hot air line through an additional An additional electric air heater and with a kindling burner at the outlet through a pre-ignition chamber installed in front of the kindling burner and connected to it with a bypass pipe in which the said electric firing device is placed, and a throttling device in the form of a narrowed channel of the calculated section is made in front of the preliminary ignition chamber in the heat treatment output section.

 Reliability of ignition in the boiler’s kindling burner is ensured by the fact that combustible gases produced in an additional line of thermal decomposition of dust ignite before the burner due to dust contact with hot air, additionally heated in an electric air heater, and the contact time is determined by the length of the heat treatment section, which can vary with using an adjusting gate mounted on the bypass duct.

 Reducing energy costs is achieved by heating the main dust entering the ignition burner due to the heat of combustion of combustible gases in the pre-ignition chamber installed in front of the ignition burner and the bypass pipe connected to it, in which the electric filling device is located. Burning gases, leaving the pre-ignition chamber through an overflow pipe with an electro-filling device, ignite and enter the ignition burner, in which the bulk of the dust entering the burner is dried. This contributes to the release of hot volatiles from the main dust and its ignition. Plugging a torch in a kindling burner is unlikely, as it is constantly illuminated by a torch exiting the pre-ignition chamber. If there is no flame in the burner, the flame detector disables the dust collectors in automatic mode to prevent the entry of non-combustible dust into the boiler.

 The existing kindling schemes do not provide for the preliminary production of combustible gases from dust, which leads to unreliable ignition, since the contact time of the dust with the electro-filling device is not enough to form the dose of gases needed for kindling. As tests on a semi-industrial test bench have shown, dust contact with hot coolant is required for 1 second to form the combustible gas needed for the fuse. Existing igniters with their length of 0.5 m and the speed of the air mixture of 20 m / s give a contact time of 0.025 seconds, which is not enough for the fuse.

 The advantage of the oil-free kindling scheme is its simplicity: thermal decomposition of dust occurs during transport of an insignificant part of the dust over a separate section from the dust bin to the burner in the presence of air additionally heated in an electric air heater. The inclusion of an electric heater, an electric kindling device is carried out only at the time of ignition of the burner. After ignition of dust in the burner, these systems are turned off.

 Due to the fact that only part of the dust is subjected to thermal destruction, the kindling circuit has high efficiency.

 A throttling device in the form of a channel with a narrowed design cross-section installed in front of the preliminary ignition chamber eliminates the breakthrough of the flame at the heat treatment section, since the speed of the air mixture in the constriction is greater than the speed of flame propagation.

 The drawing shows a diagram of an open kindling of the boiler.

 The circuit contains a dust kindling hopper 1 with dust collectors 2 and 3, a dust supply line 4 to a kindling burner 5 of a boiler furnace 6, connected to a hot air line 7 (from dust from an adjacent working boiler), and an electric firing device 8. Between a kindling dust bin 1 and a kindling burner 5 there is an additional line 9 for thermal decomposition of dust, including a heat treatment section 10 of the calculated length made in the form of a vertical loop with a bypass duct 11 and a gate 12, communicating at the inlet with the hot air line 7 through an additional a self-heating heater 13 and with a kindling burner 5 at the outlet through a pre-ignition chamber 14 installed in front of the kindling burner 5 and connected to it by a bypass pipe 15, in which the said electric firing device is placed, while a throttling device is installed in front of the preliminary ignition chamber 14 at the heat treatment outlet 16 in the form of a narrowed channel of the calculated section. The kindling burner 5 has secondary air nozzles 17 and flame sensors 18, also installed in the preliminary ignition chamber 14, connected by an actuator to the feeders 2 and 3 in automatic mode.

 The scheme of oil-free kindling of the boiler works as follows.

 The hot air line 7 is turned on with an electric air heater 13 and an electrozapalny device 8 and the entire dust system is warming up. Gate 12 is blocked. The feeder 3 is turned on (in manual mode) and the dust is supplied through the thermal decomposition line 9 to the pre-ignition chamber 14, where the ignition of the combustible gases formed in line 9 takes place from the electro-ignition device 8 through which combustible gases pass before entering the ignition burner 5. In the absence of ignition in the pre-ignition chamber 14, the flame sensors 18 automatically turn off the dust collector 3. The dust system is purged with hot air and is transferred to a more severe thermal mode dust deposits (increase in air temperature using an electric air heater 13, decrease in the amount of dust, increase in temperature of the electro-dropping device 8) and the dust collector 3 is turned on again. When igniting combustible gases in the preliminary ignition chamber 14, the dust collector 2 is turned on and dust is supplied with hot air through the supply line 4 dust into the kindling burner 5 firebox 6 boiler. 0 if there is no flame in the burner 5, the dust collector 2 is switched off by the sensor 18 installed in the burner 5. In this case, the dust collector 3, which supplies dust to the preliminary ignition chamber 14, can work if there is a flame in it. After additional heating of the kindling burner 5, the dust collector 2 is switched on again with a lower supply of dust. When the dust is ignited in the kindling burner 5, the dust collector 2 and 3 are transferred to a complete supply of dust, while the gate 12 can be opened and the electric air heater 13 is turned off. Ignition will occur due to the thermal inertia of the electrosalve device 8, which can also be turned off. When the flame is opened, the process is repeated as described. After the boiler enters the operating mode, the kindling burner 5 can be used to illuminate the torch at peak loads of the boiler or during deep unloading of mills in the absence of load (at night) as a standby burner.

 Due to the presence of the pre-ignition chamber and the production of combustible gases to the burner, flame separation at the burner 5 is unlikely, since in the event of a flame breaking off, it is again ignited due to the constant presence of flame in the pre-ignition chamber 14. The throttling device 16 eliminates the breakthrough of the flame on the plot 10 of the heat treatment of dust. The gate 12 controls the heat treatment time: when the gate is closed, the time increases, since the dust goes along a longer path through the entire loop, which allows working on different angles.

Claims (1)

 The scheme of the oil-free kindling of the boiler, containing a kindling dust bin with dust collectors, a line for supplying dust to the kindling burner of the boiler furnace connected to the hot air line, and an electric firing device, characterized in that between the kindling dust bin and the kindling burner there is an additional line for thermal decomposition of dust, including plot of heat treatment of the estimated length, made in the form of a vertical loop with a bypass duct and gate, communicating at the inlet with a hot air line through an additional An electric air heater and with a kindling burner at the outlet through a pre-ignition chamber installed in front of the kindling burner and connected to it by a bypass pipe in which the said electric firing device is placed, and a throttling device in the form of a narrowed channel of the calculated section is made in front of the preliminary ignition chamber in the heat treatment output section.