RU1772523C - Boiler with circulating layer - Google Patents

Abstract

The invention relates to a power system and can be used in power boilers burning solid fuel. The purpose of the invention is to simplify the design of the boiler and increase its efficiency. The boiler contains a shielded firebox 1 and two traps of circulating particles. The first trap is made in the form of an ash collecting beam b located on the scallop of the furnace screen 3 or on the first rows of pipes of the radiation-convective heating surface 4. The second trap 7, more efficient, is installed behind radiation-convective surfaces 4.

Description

The invention relates to a power system and can be used in boilers burning solid fuel.

Of the known technical solutions, the closest in technical essence to the claimed object (prototype) is a boiler with a circulating layer containing a furnace adjacent to the gas duct, in which at least two traps of circulating particles are connected in series, connected by return channels with a flow regulator to the firebox. The traps of circulating particles are made in the form of cooled gold-picking beams - a radiation-convective heating surface of the boiler, under which prefabricated bins with bypass windows and vibration base are installed.

The disadvantages of this boiler are low efficiency due to the narrow range of load regulation, because controlling only the total flow rate of circulating particles affects the burnup of coal in the furnace and does not affect the redistribution of heat in the radiation-convective heating surfaces of the boiler, as well as the complexity of the design, because when particles are captured only in the ash collection beam due to a sharp increase in turbulence, the efficiency of particle capture is significantly reduced in the third and subsequent rows and a large number of collection rows have to be installed; complex bins with vibration base.

The aim of the invention is to simplify the design of the boiler and increase its efficiency.

This goal is achieved in that in a boiler with a circulating layer containing a furnace adjacent to the gas duct, in which at least two traps of circulating particles are connected in series, connected by return channels with a flow regulator to the furnace, and the first particle trap along the gas made in the form of a radiation-convective tube bundle, according to the invention, the second particle trap is made in the form of an uncooled ash collector, in the channel of which

said flow regulator is installed; in addition, return channels are located adjacent to the furnace wall, made in the form of a screen of pipes equipped with

from the side of the channels upwardly facing fenders.

The combination of known and new features makes it possible to simplify the design of the boiler and increase its efficiency.

Instead of many catching

of the cooled beam behind the radiation-convective heating surfaces, an uncooled trap is installed. Moreover, due to a decrease in the volume of flue

gases and the absence of cooling pipes, the second trap is reduced in size, simplified in design and at the same time its particle capture efficiency is increased. Two stages of capture

give two streams of particles and allow independent control of the combustion process (by the flow of particles through the first trap) and the heat absorption of the radiation-convective heating surface (by the stream of particles

through the second trap) and thus expand the range of regulation of the load of the boiler, as well as its efficiency. The location of the return channels adjacent to the reverse side of the furnace screens increases their heat absorption, reducing their dimensions,

The drawing shows a longitudinal section of a boiler with a circulating layer.

The boiler contains a furnace 1 formed by

front 2, rear 3 and side screens. The furnace is adjacent to the flue with radiation-convective heating surfaces 4 (usually a superheater) and convective shaft 5. At the exit of the furnace

1 screen 3 (rear screen in the diagram) is spread into a festoon and an ash collecting beam is located on it - the first trap b, which can also be made on the first pipe rows of the radiation-convective heating surface 4. The first trap 6 can be made, for example, by installing the front generatrix of a chess bunch of festoon tubes or on the first rows of tubes of a radiation-convective surface 4

V-shaped ribs, height-partitioned by fender elements

The second trap 7 of circulating particles is installed in a stream of chilled gases, where their volume is reduced by about half compared with the volume of gases behind the furnace, so it can be made uncooled, has a small size and increased collection efficiency compared to the first trap 6.

The second trap 7 through the circulating particles return channel 8 through the flow regulator 9 is connected to the circulating particles return channel 10. In the drawing, the return channel 10 of the circulating particles adjoins the back side of the rear screen 3, which has breaker elements 11 installed with an inclination upward from the screen and connects the catcher of circulating particles 6, 7 through the motion inducer (in the diagram, ejector 12) to the furnace 1. This further simplifies the design of the boiler, as by increasing the heat absorption, the surface of the racing screens can be reduced, and the other three walls of the return channel 10 can be fixed directly to the screen 3. The return channel 10 of the circulating particles can also be implemented as an independent structure. In addition to the main elements indicated, the boiler has a fuel hopper 13 with a feeder 14, an air distribution grill 15, a fan 16, etc.

The proposed boiler operates as follows.

The crushed fuel supplied by the feed 14 from the fuel hopper 13 burns out in the furnace 1 in the flow of air heated by the fan 16 through the air distribution grill 15. Due to the flow of circulating particles, which is formed from coal ash and particles of the desiccant and heat sink to the front 2, the rear 3 and side screens, in the furnace 1, the isothermal mode of low-temperature combustion is maintained with reduced emission of harmful sulfur and nitrogen oxides, which makes this method of combustion preferred among existing ones. Typically, the parameters of the combustion process are maintained at a temperature of 800 ... 980 ° C, a gas velocity of 3 ... 8 m / s, an entrained particle size of up to 1 ... 3 mm, a dust content of the flue gas stream at the outlet of the furnace 2. ..20 kg / m3.

Next, the flue gas stream is first cleaned of large particles in the first scavenger b of circulating particles, made in the form of an ash collecting beam. Due to the large size of the entrained particles, large

part (75-95%) of the circulating particles. This reduces the heat capacity of the dusty gas stream by 2,., 10 times, i.e. almost to the level of pure flue gases, which is easier and more frequent, and also protects subsequent constructions from particle wear.

The dust content of the gas flow by small particles in front of the second trap 7 of circulating particles in this case will be greater than during pulverized coal Volumetric thermal radiation of a dusty stream and its degree of blackness increase with increasing particle concentration and decreasing particle size. The fraction of the radiation component at a temperature of 900 ... 500 ° C under these conditions turns out to be greater or close to the contribution of the convective component. Therefore, the flow regulator 9, which is installed in the canopy for returning 8 small particles, can effectively regulate the perception of radiation-convective heating surfaces 4 and steam overheating. Since the bulk of the circulating particles (70-95%) is captured by the first trap 6, this regulation has little effect It affects the furnace process itself, which significantly expands the range of regulation of the boiler load and, accordingly, its efficiency,

After separation of the streams, the flue gases are cooled in the convection shaft 5, they are sanitized from the fly ash and discharged into the atmosphere, and the circulating particles through the discharge channel 10 by the ejector 12 are returned to the furnace 1. When the return channel 10 is formed, the circulating particles are adjacent to the back wall of the screen 3 further cooled. The efficiency of their cooling and thermal perception of the screen increase with the mixing of the downward flow with fenders 11.

Using the proposed boiler with a circulating layer in comparison with the use of the prototype provides:

simplification of the boiler design, as well as the possibility of reconstruction of existing energy pulverized coal and gas-oil boilers, as the use of a two-stage trap of circulating particles in the form of a cooled ash-collecting beam and an inertial trap of the labyrinth type allows it to be placed directly in the boiler flues;

additional simplification of the boiler design when performing the return channel of circulating particles adjacent to the furnace screen;

increase in profitability since the use of a flow controller, which is installed in the return path of small particles,

it is possible to effectively regulate the heat input of radiation-convective heating surfaces and thereby deeply regulate the operation of the boiler without significantly affecting the combustion process.

Claims (2)

SUMMARY OF THE INVENTION 1. A circulating bed boiler comprising a firebox adjacent the top to a gas duct in which at least two traps of circulating particles are connected in series, connected by return channels with a flow regulator & firebox, the first one along the way The gas particle trap is made in the form of a radiation-convective tube bundle, which, in order to increase the economy and simplify the design, the second particle trap is made in the form of an uncooled ash collector, on the return line of which a flow regulator is installed. 2. The boiler according to claim 1, characterized in that the return channel of the first particle trap is located adjacent to the furnace wall, made in the form of a screen of pipes equipped with inclined fenders on the side of this channel. fifteen