JPS5839789B2 - Heating equipment for powder and granular raw materials such as cement - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heating device for a granular raw material such as cement, which comprises at least a suspension preheater and a reaction furnace, and may further include a calciner.

In a conventional firing device for cement raw materials, etc., in which a calciner is installed between a suspension preheater and a reactor such as an o-tari kiln, waste gas is collected by the second stage cyclone from the bottom that makes up the suspension preheater. The raw material is fed into the calciner through the raw material chute, collected again by the cyclone at the bottom, and fed into the rotary kiln.

In this case, a flap damper is installed in the middle of the raw material chute, and the collected raw material and pulverized coal fuel are introduced from above.

Therefore, the raw material and pulverized coal fuel input from the flap damper into the calciner are not sufficiently mixed.

As a result, uniform combustion may not occur in the calciner, resulting in incomplete combustion locally or overheating of some raw materials, which may lead to accidents such as coating adhesion and cyclone blockage. Became.

In addition, the raw materials that were mixed in advance before being charged into the suspension preheater were segregated in the cyclone, resulting in uneven quality of the products produced in the reactor.

Therefore, the main object of the present invention is to solve the above-mentioned problems by providing a heating device for feeding a powdered raw material such as cement into a reactor or calciner after mixing.

The present invention will be explained in detail below based on examples.

FIG. 1 is a system diagram of a cement raw material firing apparatus according to an embodiment of the present invention.

The calcining furnace 10 is disposed between the suspension preheater 20 and the rotary kiln 30.

The raw material powder is introduced into the duct 21 as its path is shown by the solid line arrow, is blown up by hot gas from below, undergoes heat exchange, is collected by the cyclone 22, and falls to the lower stage. Through this process, the process goes from tact 23 to cyclone 24 to duct 25 to cyclone 26, and as a result, it is preheated to about 600 to 700°C, and the limestone in the raw material is decarboxylated to about 10 to 40%.

The raw material powder from the cyclone 26 passes through the chute 2γ, and the pulverized coal fuel passes through the chute 27a to the mixer 6.
After the two are mixed together, they are introduced into a calcining furnace 10 and decarboxylated to about 90%, for example.

The raw material calcined in this way is sent to the duct 28 along with the exhaust gas.
It reaches the cyclone 29, where it is collected, guided through the chute 61, mixed by the mixer 62, and then sent to the rotary kiln 30.

In the rotary kiln 30, the raw material is burned by the burner 31 to become clinker, and is cooled by the clinker cooler 40 to become a product.

The path of hot gas is indicated by a dashed arrow.

900-110 from the raw material inlet side of rotary kiln 30
The combustion exhaust gas at about 0°C passes through the riser 11 to the calciner 10.
However, air was extracted from the clinker cooler 40.
Secondary combustion air at a high temperature of about 0.000 to 800° C. passes from the dust chamber 50 through a secondary air duct 51, is further branched into ducts 12 and 13, and reaches the calcining furnace 10.

The hot gas from the calcining furnace 10 is transferred from the duct 28 to the cyclone 2.
The powder is guided along the route 9→duct 25→cyclone 26→duct 23→cyclone 24→duct 21→cyclone 22, exchanges heat with the raw material powder, and is drawn and discharged to the outside.

FIG. 2 shows a cross section of mixer 60.

The powder raw material from the chute 27 and the pulverized coal fuel from the chute 27a are charged into the mixer 60 from above in FIG. 2, mixed while swirling like an arrow, and discharged downward in FIG. Then, the calcining furnace 10 is reached.

Inside the cylindrical housing 63 of the mixer 60, a plurality of pieces (four pieces in the figure) are in close contact with the inner wall of the housing 63 and have a length that is, for example, about 1.5 times the inner diameter of the housing 63.
The elements 64 to 61 are fixedly arranged in a straight line in this order.

Elements 64 to 67 are both made of ceramics and have the shape of a flat plate twisted 1800 degrees.

Element 64.66 is a right twist, element 6
5°67 is a left twist, and these elements 64~
The axial edges of 67 are orthogonal.

The mixture of powdered raw material and pulverized coal fuel charged from above in FIG.
2) 2, third element 66 (1/2) 3,...
It is divided into...

Since the elements 64 to 67 are arranged in a right-handed twist and a left-handed twist, the flow of the mixture is reversed, and the mixture flows from the center to the inner wall of the housing 63 along the twisted plane of the elements 64 to 67. The mixing effect is improved because the flow moves from the center to the center.

Furthermore, since the flow is divided, reversed, and converted as described above, no velocity change occurs in the axial direction, resulting in a so-called piston flow.

This type of mixer 60 has advantages such as no moving parts, low manufacturing cost, low friction, low failure rate, excellent corrosion resistance, easy maintenance and inspection, and easy heat retention and heat transfer operations. be.

Further, according to the mixer 60 having the structure shown in the second figure, since the mixer 60 is filled with a mixture, the gas from the calciner 10 does not easily flow to the shoe 27.2γa, which has been conventionally required. This eliminates the need for a flap damper.

Furthermore, since it is possible to continuously charge the calciner 10,
Stable operation becomes possible and control of the furnace internal pressure becomes easier.

Instead of the mixer 60 having the structure shown in the second figure, a mixer having another structure may be used.

For example, it may be an injector, a so-called rotating container mixer that mixes powder by placing it in a container that rotates around a horizontal axis, or a mixing blade that moves within a fixed container. It may also be a so-called fixed mixer that mixes powder and granules.

The fixed mixer may be a mixer having the structure shown in the third figure.

In FIG. 3, the powder raw material and pulverized coal fuel input from the input lower 0 are mixed by the screws 7L72, 73, discharged from the output lower 4, and guided to the calcining furnace 10.

Mixer 6 having the structure of FIG. 2 or 3 or other structure
0 is disposed between the suspension preheater 20 and the calciner 10 as described above, the combustion of the pulverized coal fuel in the calciner 10 is promoted, and unburned carbon such as - oxidized carbon CO is As a result, heat absorption of the raw material is quickly and efficiently performed, and the raw material is heated uniformly.

Therefore, the heat consumption of the calciner 10 is reduced, and problems such as coating adhesion and cyclone blockage do not occur.

In addition, due to stable combustion, the amount of secondary air supplied is less than the upper limit of secondary air that must be supplied at all times during combustion fluctuations (therefore, heat consumption is even lower). (I will be working on it.

Furthermore, complete combustion of the pulverized coal fuel and highly efficient heat exchange make it possible to easily achieve a desired calcining rate.

As the mixer 62, a mixer having a structure similar to that of the mixer 60 may be used.

This mixer 62 uniformly mixes the relatively light CaO collected by the cyclone 29 and heavy CaCO3, etc. to prevent segregation, and feeds the mixture to the kiln 30.

By mixing the raw materials by the mixer 62 in this manner, the reaction time to form clinker in the kiln 30 is shortened, and the kiln 30 can be made smaller.

FIG. 4 shows another embodiment of the invention.

In this embodiment, in order to smelt copper metal, copper oxide is heated to, for example, 800°C by a suspension preheater 80.
After being heated, the coke is guided through a chute 81 to a mixer 82, into which coke as a reducing agent and additives such as NaCl are charged through a chute 83.

After the copper oxide, the reducing agent, and the additive are uniformly mixed by a mixer 82, they are charged into a reactor 84 to obtain metallic copper.

Even in such an apparatus, the reaction in the reactor 84 is quickly carried out due to the mixing action of the mixer 82, and the reactor 84 is made smaller.

The suspension preheater 80 may be equipped with an auxiliary combustion furnace.

The invention may also be implemented as a device for heating mixed raw materials such as glass.

As described above, according to the present invention, raw materials and the like are mixed in advance by a mixer before being introduced into the reactor or calciner, so segregation of the raw materials is prevented and the reaction in the reactor or calciner is predictable. The process progresses smoothly, there is no fluctuation in the pressure inside the furnace, and stable operation is possible.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a cement raw material firing apparatus according to an embodiment of the present invention, FIG. 2 is a sectional view of a mixer 60, FIG. 3 is a simplified diagram showing another structure of the mixer 60, and FIG. 4 1 is a system diagram of a metal copper smelting apparatus according to another embodiment of the present invention. 10...Calcination furnace, 20,80...Suspension preheater, 30...Rotary kiln, 60°62.82...Mixer, 80...
...Reactor.

Claims (1)

[Claims] 1. In a heating device for granular raw materials such as cement which may be biased between a suspension preheater and a reactor and may further include a calciner, the raw material communicates with the raw material input port of at least one of the reactor or the calciner. A heating device for powdery raw materials such as cement, characterized by having a mixer disposed in the middle of a chute.