SU1071874A1 - Device for removing fly ash out of boiler - Google Patents

Abstract

A DEVICE FOR REMOVING THE VOLATILE ASH FROM THE BOILER, containing a gas duct, a mechanical ash collector, and a smoke exhauster, characterized in that the gas duct is equipped with successively installed confusors and a collector for exhaust gas with an increased concentration of solid particles attached to to the ash collector, and the total area of the collector through passage is 0.6-0.8 of the total area of the confuser cross sections.

Description

J g

BUT

//

X

/ Tfpyffe

00

. The invention relates to boiler equipment, in particular to boilers burning fuel oil. Known boiler, including ash collector, located in front of the heater, and the exhaust fan connected by a duct 1. The disadvantage of such a device is the presence of significant emissions of solid particles during periods of cleaning the tail heating surfaces. The closest to the invention to the technical essence and the achieved result is a device for removing fly ash from the boiler, including its mechanical ash collector, located after the air preheater, and the exhaust fan connected by the flue 2. A disadvantage of the known device is the low average operating degree of gas purification from solid particles, therefore, there is an increased release of particulate matter into the atmosphere. The aim of the invention is to reduce particulate emissions from the combustion of liquid fuels. The goal is achieved by the fact that, in a device for removing fly ash from a boiler containing a gas duct, a mechanical ash collector and a smoke exhauster, the gas duct is equipped with successively installed confusors and a collector for removing gas with a high concentration of solid particles attached to the ash collector, and the collector flow area is 0.6-0.8 of the total confinement flow area. FIG. 1 shows the proposed device, a general view; in fig. 2 - daily work schedule of the boiler (dependence of the boiler load on the time of day); in fig. 3 - flue, longitudinal section; FIG. 4 is a section A-A in FIG. 3; in fig. 5 is a section BB in FIG. 3. The device contains a boiler 1, a main gas duct 2 with confusors 3 and a manifold for venting gas with a concentration of solid particles 4. An additional gas duct 5 connects the collector 4 to the ash collector 6. The device also contains the main smoke exhauster 7 and the auxiliary device. In the furnace of the boiler 1, fuel oil is burned. Formed flue gases. containing solids, are directed to the main gas duct 2, in which confusors 3 are located. In confuser, flue gases having a velocity of about 15 m / s in the duct accelerate and acquire a speed of 25-30 m / s at the exit of the confuser. Subsequently, the flue gases are divided into two parts. A large part of the flue gas volume (about 70%) is directed through the main exhauster 7 into the chimney at a speed of about 15 m / s. A smaller part of the gases (about 30%) is sucked off with the help of the auxiliary smoke exhauster 8 through the collector 4 and sent to the ash collector 6, and then into the chimney. The velocity of the gases at the inlet to the suction ports of the collector is in the order of 10-15 m / s. Violation of the isokineticity of gas extraction leads to a redistribution of the amount of solid particles per unit volume of the main and sucked parts of the gases. About 20 ° / o mass of solid particles is discharged into the chimney with the main part of the gases, and about 80% of the solid particles are directed into the ash collector and further into the chimney with the sucked part. The boiler operates with variable load for a day. One of the variants of the daily work schedule of the boiler is shown in FIG. 2. When the boiler is operated at reduced loads, fuel consumption is reduced and, accordingly, the volume of flue gases is reduced. This, in turn, leads to a drop in the gas velocity in the ash collector. If for electrostatic precipitators or fabric filters, reducing the velocity of gases is a favorable factor and increases the efficiency of their work, then for dry inertial devices, on the contrary: reducing the velocity of gases reduces the efficiency of operation. This is a major disadvantage of inertial ash collectors. In the proposed system, regardless of the volume of the flue gases generated, adjusting the degree of suction, it is possible to maintain the difference in the velocities of the gases at the exit from the confuser and at the inlet to the collector orifice at 15 m / s, and the optimum amount of gases is constantly directed to the ash collector. This causes the selection of the ratio of the areas of the confuser and collector flow areas. If the diffuser and collector cross section area, respectively, F.J and the volume of gases passing through them are Qj and the velocity of gases w and Wj, then. As indicated, approximately 30% of the gases are exhausted, i.e., 3Qj. The velocities of the gases are maintained, respectively, by Wj 30 m / s, Wj 15 m / s or w, 25 m / s; w, 10 m / s, from here follows - - О 6 И1И ТГ О П t m / - 1 zitilfl ЖL about 8 1 u, -o, -w, - Increasing the velocity of gases above 50 m / s leads to an unreasonable increase in power consumption due to the sharp increase in confusion resistance. A decrease in the gas velocity below 10 m / s leads to a decrease in the volume of sucked gases, a decrease in the gas velocity in the ash collector below the optimum and, as a consequence, to a decrease in the efficiency of ash collection. The table presents the results of calculating the amount of solid emissions entering the atmosphere during the day when the fuel oil boiler TGMP-314A of the 300 MW unit is operating. Hourly consumption of fuel oil B, - 72 tons. The ash content of fuel oil A - 0.07%. The amount of combustible in gong ash is 50% (when the boiler is operating with an air-excess factor of 1.025). This means that, at full load of the boiler, M. n B A 100 / Gong 100 kg / h is taken out of it. When the boiler operates at reduced loads due to the deterioration in the quality of fuel combustion, the content of combustible sushi in ash increases naturally. It has been experimentally proved that when the fuel oil boiler is operating with a load of 75% of the decommissioning method, the dustiness of the gases increases 1.5 times, and at D 50% of the decomposition it increases 2 times. This provision is taken into account when calculating emissions of solid particles from the boiler.

Boiler load,% Number of operating hours Number of emissions Hj., From the boiler, kg Efficiency of ash collection,% Number of emissions to the atmosphere: Mt.ch. (1-7) g kg Mt. h Pre Efficiency of ash collection,% Amount of emissions to the atmosphere: (1-), kg

The table shows that in one case the emission of solid particles is EMC 980 kg, and in the other ZM ;. -882 kg, i.e. 11% less. This is due to the fact that in real conditions the amount of solid emissions from boilers equipped with inertial ash collectors is determined not by the maximum but by the average operating value of the efficiency of ash collection.

The proposed device makes it possible to increase the average operating efficiency of ash collection, makes it possible to utilize this additional amount of solid combustion products of fuel oil, which contain up to 40% of valuable raw material — vanadium pentoxide (cost of vanadium is 3 rubles per 1 kg); device and

also allows you to reduce energy costs.

In the proposed device, only a part of the gases is cleaned in the ash collector having a resistance of about 100 mm. Art., while in known devices the entire volume of gases is cleaned.

The resistance of the additional device (confuser and collector for removal of a part of gases) is about 20 mm. at. Art.

In the proposed device, the reliability of the boiler operation is also repeated.

The ash collectors installed on the ear. OTHER gases () fuel oil boilers. 1000,450 device 200180 device

Claims (1)

DEVICE FOR REMOVING FLYING ASH FROM THE BOILER containing a gas duct, a mechanical ash collector, and a smoke exhauster, characterized in that, in order to reduce particulate emissions during the combustion of liquid fuel, the gas duct is equipped with sequentially installed confusers and a collector for exhausting gas with an increased concentration of solid particles connected to the ash collector, and the total flow area of the collector is 0.6-0.8 of the total flow area of the confusers.