SU59432A2 - Suspended combustion furnace in crushed fuel - Google Patents

Description

The copyright certificate No. 9818 describes a shaft furnace for burning in a suspended state peat breeze with air supply into it from the bottom, made in the form of two adjacent and connected mines, from which the first is intended for heating and distillation of fuel, and the second for burning products coming in from the first mine.

In the proposed shaft furnace, in order to facilitate the preparation of the fuel and to ensure the required gas residence time in the gasification shaft, circulation of unburned large fuel particles was used to burn them, for which a truncated, inverted and open cone was placed in the gasification shaft. The drawing shows a schematic longitudinal section of a burner in a suspended state of crushed fuel.

The crushed fuel enters from below into a cone-shaped round shaft 1. The latter has the shape of a truncated cone, which expands upwards and passes into the cylinder. Coming into

the lower part of the air, yf, in an amount of not more than 50% of all that is necessary for burning, creates in it a stream with a gradually falling speed.

The dimensions of this shaft are so crowded that the highest speed setting in the very cross section of the cone ensures the rise of particles of the largest size, i.e., equal to or greater than the critical velocity of the particle. At an ambient temperature of 1000 ° for particles of 10 mm, the critical velocity is 40 m / s. The smallest speed in the upper section of the cone ensures the weighing of particles 0.55 mm in size, which corresponds to a speed of about 5 m / s in the same conditions.

The flow velocities in the intermediate sections will vary from 40 to 5 m / s.

Having fallen into the mine, the particles of fuel will rise to a certain level and ostaps, respectively, at their critical speeds. In suspension, in the mine, fractions that are more than 0.5 mm thick will be dried due to heat transfer from neighboring burning particles and radiation of a cladding, sublimation of volatile

and gasification or combustion. Gasification products and fuel particles smaller than 0.5 mm will be carried to the second shaft 2, where the usual dust process with the introduction of secondary air is organized.

In the first shaft, due to the presence of high particle blowing speeds, the combustion reaction is significantly accelerated. The resulting heat stress of the furnace volume will significantly exceed the loads of modern pulverized coal furnaces.

As they burn out, the fuel particles, due to the mutual continuous collision, are freed from the ash crust formed on the surface, which will also increase the intensity of burning. The ash dust will be carried out from the first mine to the second, from where normal slag removal is provided. Decreasing in size, the particles move to zones with lower speeds and, finally, having burned down to 0.5 mm, fly out of the first shaft to the second, where they burn down.

The theoretically required residence time of a particle in the first shaft, in the condition of stationary soaring in the upstream, can be arbitrarily large, and, therefore, all particles will be burned out to a specified size.

But in practice, due to the nonstationarity of the temperature field along the height of the chamber and the change in the physical properties of the particles themselves during combustion (for example, swelling), deviations from this rule are possible.

In order to facilitate the preparation of the fuel and to ensure the necessary residence time of the fuel in the gasification mine, the circulation of burning gases is organized.

particles. For this purpose, a truncated cone 6 opened on both sides is placed in mine I.

Outside the cone 6, an annular space 3 is formed, where the fuel particles return to the lower base of the cone and through the annular slot 4 are again captured by the ejecting flow, together with part of the hot flue gases.

In order to prevent slagging, the walls of the cone are covered with screen tubes 5 and the temperature in the first shaft is maintained no higher than 1000 to 1100 ° C.

Load control of the furnace is made by changing the number of gasification mines in operation. For this purpose, several gasification mines (for example, four) are used, operating in parallel for one common, secondary mine.

Such regulation allows changing the load over a wide range, without reducing the economy and not violating the principle of combustion.

The pressure of the air entering the shaft is not higher than 100-150 mm. with.

In view of the large thermal stresses of the first shaft, the overall dimensions of the proposed double shaft furnace will not exceed the dimensions of the existing coal-burning furnaces,

The subject matter of the invention.

The combustion chamber in a suspended state of crushed fuel according to the author's certificate No. 9818, characterized with the use of a truncated inverted cone open on both sides, placed in the gasification shaft for circulating burned large particles of fuel, with a view to after-burning them.

E dependent copyright certificate

No. 59482

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