JPS58151353A - Method of burning cement raw material using powdery raw material containing combustible content - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] The present invention relates to a method for firing cement raw materials that uses powder raw materials containing combustible components such as oil shale, botanicals, and low-grade coal in addition to the usual non-combustible main powder raw materials. It is.

Conventionally, several proposals have been made regarding methods for firing cement raw materials that use raw materials containing combustible components such as those described above in addition to ordinary raw materials.

Among these, the first method is to use conventional equipment.
One example is one that supplies powdered raw material containing combustible matter to the upper stage of a preheater consisting of a suspension preheater. However, when raw materials containing combustible components are supplied to the upper stage of the preheater, the temperature of the exhaust gas rises, resulting in increased heat output as sensible heat, and unburned components remain in the dust contained in the exhaust gas. Therefore, it is impossible for the supplied combustibles to contribute in full.

Normally, the contribution is only around 50%. Also, unless the calorie content of the feedstock is kept at about 100 Kcal per kg of clinker, the preheater exhaust gas will become too high, which will cause problems in operation. Therefore, it is preferable to supply the raw material containing combustible components to the lower stage of the preheater separately from other raw materials.

Therefore, a method has been proposed in which a centrifugal furnace is provided that is separate from the gas flow flowing from the rotary kiln to the cyclone at the lowermost stage of the preheater, and raw materials containing flammable components are supplied to the centrifugal furnace. However, in this method using a centrifugal furnace, if room temperature air is used as the combustion air in the centrifugal furnace, the fuel consumption of the all-zero system will increase, and if high temperature exhaust from the clinker cooler is used, the fuel consumption will increase after the preheater. Either a dedicated exhaust gas fan for the centrifugal furnace is required, or a fan needs to be inserted in the gas flow from the clinker cooler to the centrifugal furnace. The clinker dust contained in the airflow causes severe wear and tear, making it unusable. Another disadvantage is that the cost of providing a separate centrifugal furnace and associated equipment is increased.

As a way to overcome this drawback, raw materials containing combustible components are
A method was proposed in which the fuel was fed into a conduit leading from the rotary kiln to the lowest cyclone of the preheater and burned in this conduit. However, from the point of view of mixing, the raw materials supplied to the straight gas flow in the conduit tend to cause one-sided flow, and therefore, the mixing of the two types of raw materials cannot be good in the conduit, and the mixing is difficult. In bad cases, the quality of cement clinker will deteriorate.

Furthermore, structures such as a stirring plate for increasing the mixing effect are expected to be difficult in terms of materials because they are used in high-temperature gas from a rotary kiln at a temperature of 1000 to 1200°C. On the other hand, in terms of the combustion of combustibles, the air required for combustion is primarily the exhaust gas of the rotary kiln, so the concentration of fluorine in the exhaust gas is 10 to 16%, and low-grade solid fuel However, the flammable components of the raw materials have poor combustibility, and the time required for combustion is significantly longer than in the atmosphere. In addition, in order to improve the mixing effect, placing the supply ports of calcareous raw materials and clay raw materials containing combustibles close together may improve the mixing, but it will cause the calcareous raw materials to burn in an atmosphere where an endothermic reaction occurs due to decarboxylation. This means that combustion will worsen.

The present invention aims to solve the above-mentioned problems and eliminate the drawbacks.

For this reason, the present invention is characterized in that the powder raw material containing combustible materials is supplied to the recirculation region, and the other powder raw materials are supplied to the suspension preheater.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram showing an example of cement clinker manufacturing equipment for implementing the present invention.

In FIG. 1, 1 is a preheater consisting of a suspension preheater, 2 is a supply port for powder raw materials other than powder raw materials containing combustible components, which are supplied to the upper stage of the preheater 1, and 3 is a supply port for the preheater 1.
The lowest cyclone among the cyclones that make up the
4 is a cyclone directly above the cyclone 6; 5 is a calcining furnace; 6 is a duct connecting the calcining furnace 5 and the lowermost cyclone 3; 7 is a chute for guiding the raw material from the cyclone 4 to the calcining furnace 5. , 8 is a supply port for a powder raw material containing combustible matter, 9 is an auxiliary burner, 10 is a duct that guides the high-temperature cooler exhaust from a clinker cooler 14 (described later) to the calciner 5, and 11 is a kiln of a rotary kiln 16 (described later). The exhaust gas is transferred to the calciner 5.
A kiln riser duct 12 is a chute that supplies the raw material from the lowermost cyclone 3 to the rotary kiln 13. That is, the calcining furnace 5 is provided in the middle of the gas flow from the rotary kiln 13 to the lowermost cyclone 3 of the preheater 1, and therefore, the kiln exhaust gas from the rotary kiln 13 passes through the kiln riser duct 11 to the calcining furnace. 5, and the high temperature cooler exhaust from the clinker cooler 14 is supplied to the calciner 5 through a duct 10 as combustion air for the calciner 5.

2 is an enlarged vertical sectional view of the calcining furnace 5 shown in FIG. 1, and FIG. 3 is a sectional plan view taken along the line MA-A in FIG. 2.

15 shown in FIGS. 2 and 5 is a vortex chamber, and the calcining furnace 5
The clinker cooler 1 explained in FIG.
This is provided to make the cooler exhaust air 19 from 4 into a swirling flow. 16 is a raw material inlet for introducing the raw material into the calciner 5 from the chute 7 explained in FIG. 1; 17 is a raw material inlet for introducing the raw material from the chute 7 into the middle of the kiln rising duct 11; shows the flow of kiln exhaust gas.

Next, an embodiment of the present invention will be described with reference to FIG.

The raw materials for cement clinker are composed of calcareous raw materials and clay raw materials. In addition, other auxiliary raw materials are often added because it is necessary to adjust the quality of clinker. The clay raw material and the calcareous raw material containing combustible components are separately pulverized by a pulverizer.

The lid, if necessary, will add clay raw materials that do not contain combustible content, but these additives will be crushed at the same time as the clay raw materials that contain combustible matter, and will not be mixed with calcareous raw materials. Even if they are crushed at the same time, there is no particular relationship with the present invention. From now on, even though other raw materials may be added to the clay raw material containing combustible matter, this will be referred to as "clay raw material containing combustible matter," and the main material will be crushed in a separate series. Raw materials with calcareous components are called "other raw materials."

First, other raw materials are supplied to the raw material supply port 2 in the upper part of the preheater 1, and as they descend inside the preheater 1, they undergo heat exchange with the gas flow! 2 The temperature rises. And cyclone 4
The other raw materials collected in the above pass through the chute 7 and are supplied to the calciner 5. On the other hand, the clay raw material containing combustible matter is supplied from the supply port 8 to the lower part of the calciner 5. The supplied clay raw material containing combustible matter is burned in the calcining furnace 5 and simultaneously mixed with the other raw materials mentioned above, as will be described later.

Due to the equipment shown in Figure 1, approximately 50 to 60% of the heat required to produce cement clinker is consumed in the calciner 5.
However, it is also possible to replace all the heated rice cake with the combustible content of the raw materials. However, since the combustible content in the raw materials usually fluctuates, 10 to 20% of the heat consumed in the calciner 5
Normally, this is supplemented with an auxiliary burner 9 such as heavy oil or gas.

The auxiliary raw materials undergo a calcination reaction and a calcination reaction inside the calcination furnace 5, pass through a duct 6, are introduced into the cyclone 3, are collected, pass through a chute 12, and enter a rotary kiln 13. The rotary kiln 13 and the subsequent clinker cooler 14 are similar to normal equipment. High-temperature cooler exhaust from the clinker cooler 14 passes through the duct 10, is introduced into a vortex chamber provided at the bottom of the calciner 5, which will be described later, and is used as secondary air for combustion in the calciner 5. . Although not shown in the drawings, the cooler exhaust amount can be determined by controlling the opening degree of a damper provided in the middle of the duct 10.
It is possible to increase or decrease the amount as desired; therefore, the minimum necessary amount is introduced into the calcining furnace 5.

Next, the function and effect of the calcining furnace 5 will be explained with reference to FIG. It forms part of the calcining furnace 5 and is provided at the bottom of it.
As shown in FIG. 3, the inlet of the cooler exhaust 19, which is the hot air from the clinker cooler 14, is in the tangential direction of the vortex chamber 15, so the cooler exhaust 19 does not swirl. It has a structure in which the calcining furnace 5 is raised.

Since the clay raw material containing combustible components is supplied from the supply port 8 installed on the ceiling of the vortex chamber 15, the first thing it comes into contact with is the cooler exhaust 19 from the clinker cooler 14, and this exhaust Since the hot air has a temperature of 600 to 750°C, and the ignition temperature of the combustibles is about 500°C, the combustibles can self-combust. Also, since the hot air is originally taken from the atmosphere, it has a high oxygen concentration and burns quickly. Thereafter, it merges with the kiln exhaust gas flow 18 and proceeds to the upper part of the calciner 5, but the swirling of the hot air has the advantage that mixing of the kiln exhaust gas and the hot air is good. On the other hand, other raw materials are usually supplied in half amounts from the chineto 7 to the supply ports 16 and 17, and mixed with the raw materials from the supply port 8 in the swirling gas in the calciner 5. In this mixing, the swirling of the gas flow is very effective.

The purpose of the auxiliary burner 9 is to compensate for fluctuations in the combustible content of the raw material, but it can also be used for the purpose of promoting the combustion of the combustible content, so its position is determined while considering the position of the supply port 8. be done.

As described above, the present invention supplies the powdered raw material containing combustibles to the lower swirl chamber of the calciner, so there is no problem with the conventional method of supplying the raw material to the upper stage of the preheater, and it also There is no need to install a separate equipment, and since the supply location is the high-temperature cooler exhaust with high oxygen concentration before mixing with the kiln exhaust gas, combustion is good and the total amount of heat held by the combustibles is effectively utilized. Not only can it be used, but it is also the swirling area for the cooler exhaust air, so it has good diffusion and good mixing with other raw materials that are supplied to the upper stage of the preheater and reach the calciner. , You can get good quality promotion/・Tokuri・Power.

[Brief explanation of the drawing]

The drawings show an example of an apparatus for carrying out the present invention, in which Fig. 1 is a schematic explanatory diagram of the entire equipment, Fig. 2 is an enlarged vertical cross-sectional view of the calciner, and Fig. 3 is a cutting line of Fig. 2. FIG. 3 is a cross-sectional plan view taken along line A-A. 1... Preheater, 2... Other raw material supply ports, 5...
・Calcination furnace, 8... Supply port for raw materials containing combustibles, 9...
・Auxiliary burner, 13...Rotary kiln, 14...
Clinker cooler. 15... Vortex chamber, 18... Kiln exhaust gas flow. 19... Cooler exhaust.

Claims (1)

[Claims] 1. Suspension preheater and rotary kiln,
A calcining furnace provided in the middle of the gas flow from the rotary kiln to the lowermost cyclone of the preheater, and a clinker cooler provided subsequent to the rotary kiln, and the calcining furnace includes: In a method of firing cement raw materials using a cement firing equipment having a vortex chamber in the lower part of which introduces high-temperature cooler exhaust air from the clinker cooler as combustion air to create a swirling flow, the powder raw materials containing combustible components are A cement raw material using a powder raw material containing combustible content, characterized in that the powder raw material is supplied to the swirl region of the cooler exhaust gas before being mixed with the kiln exhaust gas in the vortex chamber of the furnace, and other powder raw materials are supplied to the suspension preheater. Firing method.