DE4337068A1 - Process and apparatus for heat treating fine-grained material - Google Patents

Abstract

The invention relates to a process and an apparatus for heat treating fine-grained material in a reaction compartment to which fuel is fed at at least one point, the fuel being measured so that on the one hand the permissible volumetric heat load of the reaction compartment and on the other hand the permissible area heat load of the cross-sectional area of the reaction compartment is not exceeded in the region of the fuel feed. The minimum distance between two feed devices is determined by the permissable volumetric heat load of the volume section of the reaction chamber between the two feed devices.

Description

The invention relates to a method according to the Oberbe handle of claim 1 and a device correspond chend the generic term of claim 3 for heat act of fine-grained goods.

Such a method is used, for example, at Calcination of raw meal in cement production agile. The one introduced into the reaction space Fuel mixes with the raw meal particles containing gas stream and burns. Although it is in has proven to be particularly advantageous in practice if as large a quantity of fuel as possible is not allowed to overheat the Lead reaction chamber, because then there will be one Clumping of melted ash and raw meal particles and it also increases the consumption of refractory Materials for the lining of the reaction space.

Based on the chemical analysis of the fuels and the practical experience using these fuels in calcinators one has for the individual fuels permissible heat volume loads in the reaction chamber derived. So the permissible heat volume is load for normal reactive hard coal about 90,000 to 130,000 kcal / m³h. For oil, this value is approximately 180,000 kcal / m³h.

So far, these have been used in the operation of calcinators Limit values taken into account. These limits can however, often cannot be achieved anywhere near it  already clumping or local Overheating is coming.

The invention is therefore based on the object Method according to the preamble of claim 1 or the device according to the generic term of the Anspru ches 3 to develop in such a way that an increased Amount of fuel can be supplied without it becoming a local overheating or clumping with ashes to come.

This task is carried out with regard to the method according to the characterizing features of claim 1 solved in to which the amount of fuel supplied is such sen is that on the one hand the permissible heat volume load of the reaction space and on the other hand the perm sige thermal surface load of the cross-sectional area of the Reaction space in the area of the fuel supply is not is exceeded.

Regarding the device, the task by characterizing features of claim 3 solved, wherein the minimum distance between two feeders for fuel by the permissible heat volume loading of the volume section of the reaction chamber between the two feeders is determined.

With the method or the device according to the invention an increased amount of fuel can be burned, while improving the degree of calcination and a more uniform temperature profile is achieved.

Further embodiments of the invention are the subject of the dependent claims and are explained in more detail with reference to the following description of an embodiment and the drawing:
The device shown in the drawing for heat treatment of fine-grained material is formed by a cal cinator for the treatment of raw meal in the cement production. It essentially consists of a reaction chamber 1 forming a reaction chamber, a device 2 for introducing, and a device 3 for discharging the gas stream loaded with the raw meal particles. At the reaction chamber 1 three feed devices 4 a, 4 b, 4 c for fuel are also seen before. However, the number of feed devices is not limited to three, but rather only two or more feed devices can be provided.

Based on the chemical analysis of the fuels and the practical experience using these fuels in calculators one has limit values for the maximum allowable amount of fuel that is fed can be, so that still a satisfactory Combustion is possible. In particular, the Reactivity of different fuels Role. The burning behavior of a fuel will determined on the basis of analyzes of the flue gases. The thereby depending on the time gained curves provide information about the ignition behavior, the Main burning phase and the burnout behavior of this Fuels. The knowledge gained thereby was with practical experience in operating Calci nators compared, so that this results in limit values for result in the heat volume or heat surface load to have. Under the permissible thermal surface load  that at a certain cross-sectional area per hour supplied amount of heat understood, in which another clean combustion is possible. Under one satisfactory combustion is particularly one Combustion without local overheating or clumping too understand. With the permissible heat volume load one calls the maximum of a certain volume amount of heat that can be supplied, below which another satisfactory combustion is possible.

The following applies, for example, to the permissible thermal surface load:
Normally reactive hard coal: q _A approx. 0.5 _* 10⁶ kcal / m²h
Oil: q _A approx. 1 _* 10⁶ kcal / m²h
The following applies to the permissible heat volume load:
Normally reactive hard coal: q _V approx. 0.5 _* 10⁶ kcal / m³h oil: q _V approx. 1 _* 10⁶ kcal / m³h.

The following applies to the permissible heat volume load in relation to the entire reaction space:
Normally reactive hard coal:
q _Vtotal approx. 0.09 _* 10⁶ to 0.13 _* 10⁶ kcal / m³h
Oil: q _Vtotal approx. 0.18 _* 10⁶ kcal / m³h.

Taking into account the above limit values, a device according to the invention for the heat treatment of fine-grained material can be designed as follows:
The speed of the gas stream 5 loaded with the fine-grained material determines the cross section of the reaction chamber 1 . The minimum distances l 1 and l 2 between the first and second feed devices 4 a, 4 b and between the second and third feed devices 4 b and 4 c are determined as follows:
The maximum amount of fuel that can be introduced per hour at the first feed device 4 a is determined according to the formula:

Q₁ = A₁ _* q _A

with A₁ the cross-sectional area on the first feed device 4 a is designated.

The distance l₁ between the first and second feed device 4 a, 4 b must now be selected at least so large that the permissible heat volume load q _V in the volume between the two feed devices is not exceeded. If, for the sake of simplicity, it is assumed that the reaction chamber is cylindrical, that is to say that the cross-sectional areas A 1, A 2, A 3 are each of the same size, the volume V 1 between the first and second feed devices 4 a, 4 b results according to the formula:

V₁ = A₁ _* l₁

The minimum distance l 1 then results as follows:

Q₁ / q _V = A₁ _* l₁

it follows

l₁ = Q₁ / (q _{V *} A₁)

Assuming by way of example assumed that the cross-sectional area A₁ 6 is m² and processing at the first Zuführeinrich 4 a normal reactive coal is supplied, then the above formulas results in accordance with a minimum distance L₁ to the second feeder 4 b of

l₁ = (0.5 _* 10⁶ kcal / m²h _* 6 m²) / (0.5 _* 10⁶ kcal / m³h _* 6 m²) = 1 m

The distance 12 or the distances to further feed devices can also be calculated in an analogous manner.

With the Ge fed at all feeding devices However, the total amount of heat must not be the permissible volume load on the entire reaction chamber exceeded become. The number of feeders and / or the heat supplied to the individual feed devices this limits the quantity.

The heat quantities supplied to the individual feed devices Q 1, Q ₂ , Q 3 are therefore such that, on the one hand, the permissible heat volume load q _{Vtotal of} the reaction _space and, on the other hand, the permissible thermal surface load q _{A of} the cross-sectional area of the reaction space in the area of the fuel supply is not exceeded.

Such a device operated and designed for Heat treatment of fine-grained material stands out through a more uniform temperature profile within  the reaction chamber, better burnout conditions as well a higher degree of calcination. Although opposite conventional devices a larger amount Local overheating occurs when fuel can be supplied avoided, which also makes the refractory mate wear less materials in the reaction chamber. Finally, the devices, due to the optimal heat distribution within the reaction chamber, can be designed smaller.

In the experiments on which the invention is based, it has also been shown that the CO content after the device does not increase and the NO _x content is even reduced.

Claims (3)

1. A method for the heat treatment of fine-grained material in a reaction chamber, to which fuel is supplied at at least one point, characterized by such a dimensioning of the fuel that on the one hand the permissible heat volume _load q _{Vtotal of} the reaction chamber and on the other hand the permissible thermal surface load q _{A of} the cross-sectional area (A₁ , A₂, A₃) of the reaction space in the area of the fuel supply is not exceeded. 2. The method according to claim 1, characterized in that the permissible heat volume load q _V of the volume portion assigned to the supplied fuel (V₁, V₂, V₃) of the reaction space is not exceeded. 3. Device for the heat treatment of fine-grained material with a reaction chamber forming a reaction chamber ( 1 ) and at least two feed devices ( 4 a, 4 b, 4 c) for fuel, characterized in that the minimum was from ( 11 , 12 ) between two feeders determined by the allowable heat volume load q _{V of} the volume section (V₁, V₂) of the reaction chamber between the two feeders.