JPS62283848A - Method and apparatus for removing volatile contents in cement burning facilities - 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 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to the removal of volatile components such as alkali contained in raw materials in cement firing equipment.

<Prior Art> A conventional cement firing facility has a configuration as shown in FIG. 2, for example.

In FIG. 2, 1 is a suspension preheater, 2 is a firing furnace, in this example a rotary kiln, 3 is a tarinka cooler, 4 is a powder material transporter, 5 is a main exhaust fan, and 6 is a calciner.

That is, the powder raw material is introduced into the suspension preheater 1 by the transport R4, exchanges heat with high-temperature gas in each cyclone, reaches the calciner 6, is calcined here in the calciner burner 8, and is input into the rotary kiln 2. be done.

The raw material input into the rotary kiln 2 is
It gradually flows down due to the rotation of the kiln burner 9, and the kiln burner 9
, is heated to 450° C. and fired to become tarinka for cement, and is then put into the tarinka cooler 3 as shown by arrow 14, where it is cooled and becomes tarinka 18.

The air sent to the cooler 3 by the cooling air blower 10 exchanges heat with the high-temperature tarinka and is divided into three parts, and the highest temperature air is sent to the rotary kiln 2 as shown by the arrow 15. It becomes secondary air for combustion. The next medium-temperature air becomes secondary air for combustion in the calciner 6 as shown by arrow 7.

The remaining low-temperature excess air from the cooler reaches the dust collector 11 as shown by arrow 16, where it is removed with dust and discharged out of the system.

The exhaust gas from the rotary kiln 2 exchanges heat with the raw material in the calciner 6 and the suspension preheater 1, and then passes through the main exhaust fan 5.
induced by.

In the above explanation, a cement firing equipment equipped with a calcining furnace 6 has been described, but there is also a cement firing equipment without the calcining furnace 6 and consisting of a kiln and a suspension preheater. In addition to rotary kilns, there are also fluidized bed kilns.

N contained in raw materials in such cement firing equipment
Alkaline components such as az○, K2O, SO3, etc. are approximately 1,
It has the property of evaporating at around 400°C (hereinafter referred to as volatile content), and when passing through the operating temperature zone of the rotary kiln 2 at 450°C, it evaporates from the raw material, becomes a gas, and enters the combustion gas of the rotary kiln. The gas in this kiln is approximately +,000~+,+0 at the gas outlet side 13 of the rotary kiln.
Although the temperature is 0°C, heat is exchanged with the raw material in the suspension preheater 1, and the temperature is cooled to approximately 350°C, and then the main discharge I! Attracted by 1 aircraft 5.

On the other hand, since the vaporized volatile matter condenses at 800 to 850°C, it adheres to the raw materials and furnace walls that are in this temperature range. The volatile matter adhering to the raw material flows down again and is heated/evaporated in the rotary kiln 2 as described above, and enters the kiln gas.

Thus, the volatile matter is circulated between the rotary kiln and the suspension preheater, so that the rotary kiln and the suspension preheater are operated in a concentrated state. When this volatile content increases, the following problems occur.

(1) Volatile matter adheres to the inner walls of the suspension preheater 1 and the riser duct 19 and gradually grows, obstructing the gas flow and making it impossible to operate.

■ When volatile content increases in the raw materials in the suspension preheater, the raw materials become sticky and stick to each other, making suspension system operation impossible.

■ Alkaline content in the product's talin content increases.

The alkali in the talin eventually becomes the alkali in the cement, which is currently the cause of the alkali problem. In the United States, this alkali content is regulated at 0.6% or less.

As a countermeasure for the above (1) to ■, the conventional rising duct 19
It has been put into practical use to take out a portion of the kiln exhaust gas outside the system to avoid concentration of volatile components.

As shown in FIG. 3, part of the kiln exhaust gas at +,000 to i, 100°C is drawn into the cooling tower 21 from the middle of the rising duct 19 through the duct 20, and the water pressurized by the pump 22 is sent to the nozzle 23. The high temperature gas is sprayed from about 350℃.
Rapidly cool to ℃. Since this kiln exhaust gas contains a large amount of dust, volatile matter in the airflow adheres to the surface of the rapidly cooled dust. The gas exiting the cooling tower 21 is further collected through an electric precipitator 25, and is drawn out by an exhaust fan 26 and disposed of outside the system. Relatively large particles fall to the bottom of the cooling tower 21 and are taken out of the yarn by a conveyor 29 as dust. Further, the dust collected by the electrostatic precipitator 25 is also taken out of the system by the conveyor 30. To prevent alkali from adhering to the duct 20, send I! At 18 and 27, cold air is blown from the outer periphery to the outlet of the rising duct 19, and the high temperature gas is guided to the cooling tower 21 so as to be surrounded by the cold air. 21 cooling towers in Arab countries without water
Instead of injecting water, the air volume of the blower 27 is increased to 350℃
It is cooled down to.

<Problems to be Solved by the Invention> The conventional volatile matter removal apparatus as described above has the following problems.

(1) High-temperature kiln exhaust gas is extracted and disposed of outside the system, and that amount becomes heat loss, which worsens the unit heat energy consumption.

■ Since volatile matter is removed by attaching it to the dust in the kiln exhaust gas, a large amount of dust is generated, the processing cost is high, and it becomes a source of dust pollution. Furthermore, since the dust in the kiln exhaust gas is originally a raw material for cement, the product yield deteriorates.

■ Electrostatic precipitators are expensive, so the entire devolatilization device is expensive.

<Object of the Invention> The present invention was devised in view of the problems of conventional devolatilization devices. Volatiles are removed by evaporation on the surface of coarse grains, and the kiln exhaust gas is returned to the suspension preheater, resulting in low thermal energy consumption, less dust generation, and less volatile matter in inexpensive cement firing equipment. The object of the present invention is to provide a removal method and apparatus.

Means for Solving the Problems In order to achieve the above object, the method for removing volatile matter in cement firing equipment according to the first invention of the present application is to remove volatile matter from the vicinity of the firing furnace exhaust gas outlet of cement firing equipment equipped with a firing furnace and a suspension preheater. In a method for removing volatile matter in cement firing equipment, which reduces the concentration of volatile matter circulating between the kiln and suspension preheater by extracting a part of the kiln flue gas, a part of the kiln flue gas discharged above is transferred to an adsorption tower. It is brought into contact with low-temperature coarse particles that fall in a pattern while flowing through the adsorption tower, and the volatile matter is adsorbed on its surface. The feature is that the temperature is returned to a portion of the temperature range approximately equal to .

Further, the volatile matter removal device for cement firing equipment according to the second invention of the present application is a cement firing equipment equipped with a firing furnace and a suspension preheater. In a volatile matter removal device in a cement firing facility that reduces the concentration of volatile matter circulating in cement, an adsorption tower that receives the extracted firing furnace exhaust gas, a cooling means for cooling or cleaning the coarse particles sent from the adsorption tower, and a device for removing volatile matter from the cooling means. It is equipped with a return means for returning the cooled coarse particles to the adsorption tower, and a duct for returning the calcining furnace exhaust gas treated in the adsorption tower to a part of the suspension preheater pipe system in a temperature range approximately equal to the temperature of the exhaust gas, and the adsorption tower The apparatus is characterized in that it is equipped with a dispersing means for causing low-temperature coarse particles to fall in a pattern, and the volatile matter in the firing furnace exhaust gas is adsorbed onto the surface of the low-temperature coarse particles falling in a pattern.

<Operation> A part of the exhaust gas from the calcining furnace at a high temperature of about 1,000°C is extracted and guided to an adsorption tower, where it is brought into contact with low-temperature coarse particles that fall in a pattern while the gas rises inside the tower. Volatile matter that comes into contact with the coarse particles condenses as the temperature decreases and is adsorbed on the surface of the coarse particles.

The treated kiln exhaust gas has a temperature of about 700° C. to 850° C., and is returned to a portion of the suspension preheater pipe system having a substantially equal temperature range. On the other hand, since the temperature of the coarse particles that have adsorbed volatile matter has risen to about 500° C., they are cooled to around room temperature by a cooling means and guided to the adsorption tower again. If sand or the like is available in large quantities, it may be possible to cool it naturally while it is piled up outdoors without installing a special cooler, and recycle some of it while replenishing it.

<Embodiment> An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a flow sheet of the devolatilization device in the cement firing equipment of the present invention. In Fig. 1, 1 is a suspension preheater, the first stage cyclone 1c, the second stage cyclone 1c,
It consists of a stage cyclone 2c, a third stage cyclone 3C, a fourth stage cyclone 4C, and a pipe system connecting them. 2 is a firing furnace, in this example a rotary kiln, 3 is a cooler,
6 is a calcining furnace, 13 is a rotary kiln exhaust gas outlet, 19
is a rising duct. 40 is a central outlet duct for extracting part of the kiln exhaust gas from the rising duct 19; 41;
4 is an adsorption tower, 43 is a return duct returning from the adsorption tower 41 to the suspension preheater, 44 is a seal damper such as a double flap, 45 is a cooling means, and 46 is a return means, which includes a packet elevator 46a, a hopper 46b1, and a quantitative supply 1146c.
, a packet elevator 46d, and a seal damper 46e. 48 is a dispersing means provided at the top of the adsorption tower 41 to cause coarse particles to fall in a mountain shape within the adsorption tower.

Although the cement firing apparatus in FIG. 1 is equipped with a calcining furnace 6, the calcining furnace 6 may not be provided, and the number of stages of the suspension preheater 1 may be increased or decreased. Also, the firing furnace is flow 1)
316 type may be used. The adsorption tower has a gas inlet 41a at the bottom, a gas outlet 41b at the top, and a coarse particle inlet 41 at the top.
C1 has a coarse grain outlet 41d at the bottom, and a coarse grain inlet 41 at the top.
A dispersing means 48 is provided near c.

The dispersion means 48 is a means for uniformly distributing the received coarse particles in a mountain shape within the adsorption tower 41, and for example, a vibrating screen or the like is used.

The coarse particles falling in the adsorption tower 41 are made of sand, iron powder, iron balls, etc. having a weight sufficient to prevent them from being carried away by the gas, such as sand, iron powder, or iron balls having an average diameter of about 1+n+n. The height of the adsorption tower 41 is determined by the material and shape of the coarse particles so that while the coarse particles fall through the adsorption tower 41, the volatile matter in the kiln exhaust gas has a sufficient retention time to be adsorbed on the surface of the coarse particles. It can be decided according to.

In addition, in FIG. 1, the kiln exhaust gas flows upward in the adsorption tower 41,
Although this is a countercurrent type in which the coarse particles flow downward, a parallel flow type in which the kiln exhaust gas flows downward may also be used.

The cooling means 45 is a means for cooling the coarse particles that have become high temperature in the adsorption tower 41 to room temperature, and includes a rotary cooler that circulates cold air in the rotary drum, and a shower provided in the rotary drum to cool the coarse particles and adsorb them onto the surface of the coarse particles. A rotary washer that cleans the volatile matter that is left behind, a pond washer that runs a drag conveyor on the bottom of the bond that stores water and scrapes out the coarse grains that are thrown into the pond, and a natural cooling type that simply piles up the coarse grains outdoors. etc., as appropriate depending on the situation. When cleaning, it can be reused as many times as desired, but when simply cooling, the particle size of the coarse grains gradually increases due to the adsorption of volatile matter, so some of the coarse grains must be replaced with new ones for reuse. Become.

The return means 46 is a means for returning the cooled coarse particles to the top of the adsorption tower 41, and as shown in the figure, there is a packet elevator 46a,
466 etc. are used. Although the hopper 46b is provided to temporarily store coarse particles and improve the stability of operation of the volatile matter removal device, it may be omitted.

The action will be explained below.

1,000 from kiln 2 to calciner 6 in cement firing equipment.
Exhaust gas at about 0° C. is sent, and the exhaust gas contains volatile components such as alkali components. Approximately 10 to 30% of the exhaust gas is extracted from the riser 19 through the duct 40 and sent to the gas port 41a of the adsorption tower 41. Adsorption tower 4
While the exhaust gas at 1,000° C. rises inside the adsorption tower 41, it comes into contact with coarse particles raining down from the top of the adsorption tower 41 in a counterflow state. Since the coarse grains are at room temperature or slightly higher than normal temperature, when they come into contact with exhaust gas, the gas near the assembled grains is cooled and the volatile matter contained therein is adsorbed on the surface. Exhaust gas after treatment is 85
It is cooled to about 0° C. and is returned from the adsorption tower 41 to the pipe system of the suspension preheater 1 through a return duct 43. Suspension preheater 4th pipe of 1
At the exit of stage cyclone 4C, the temperature is about 850°C, so it is returned there. On the other hand, the coarse particles that have descended inside the adsorption tower 41 are heated to about 400 to 500°C and are heated to a coarse particle outlet 4 at the bottom.
1d, and is sent to the cooling means 45 via the seal damper 44. The coarse particles are cooled or washed by the cooling means 45, and the coarse particles after treatment are sent to the adsorption tower 4 by the return means 46.
1. Returned to the top. The returned coarse particles are uniformly dropped into the adsorption tower 41 in a mountain shape by the dispersing means 48. The coarse particles are thus recycled.

<Modification> FIG. 4 is a flow sheet of a modification of the present invention. The difference from Fig. 1 is that the kiln exhaust gas is cooled to about 700°C in the adsorption tower 41, and is therefore returned to the third stage cyclone outlet (exit temperature 750°C) in the pipe system of the suspension preheater 1. ing.

It goes without saying that the present invention is not limited to the above-described embodiments or modified examples, and that various modifications can be made within the scope of the claims.

<Effects of the Invention> As described above, the method and device for removing volatile matter in cement firing equipment of the present invention has the following effects.

(1) Volatile matter in the kiln exhaust gas is removed without significantly lowering the temperature of the exhaust gas, resulting in less loss of thermal energy and improved fuel consumption for firing.

■ Unlike the conventional method in which volatile matter is adsorbed using dust from kiln exhaust gas as a nucleus, this method adsorbs volatile matter into coarse particles, so the amount of dust generated is small and there is less risk of dust pollution, and the dust in the exhaust gas is lost. Product yield is also improved.

(3) Equipment costs are low because an electric precipitator for removing volatile matter is not required.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet of the volatile matter removal device in the cement firing equipment of the present invention, FIG. 2 is a flow sheet of the conventional cement firing equipment, and FIG. 3 is a flow sheet of the volatile matter removal device in the conventional cement firing equipment. FIG. 4 is a flow sheet of a modification of the present invention. 1... Suspension preheater 2...
・Rotary kiln 41...Adsorption tower 45...Cooling means 46...Returning means 48...Dispersion means Fig. 2

Claims (2)

[Claims] (1) Cement firing equipment that reduces the concentration of volatile matter circulating between the kiln and the suspension preheater by extracting part of the kiln exhaust gas from the vicinity of the kiln furnace exhaust gas outlet of the cement kiln equipment equipped with a kiln and a suspension preheater. In the volatile matter removal method, a part of the above-mentioned extracted firing furnace exhaust gas is led to an adsorption tower, and while flowing in the adsorption tower, it is brought into contact with low-temperature coarse particles that fall in the form of rain, and the volatile matter is adsorbed on the surface thereof. A method for removing volatile matter in cement firing equipment, characterized in that the treated firing furnace exhaust gas from the adsorption tower is returned to a part of the suspension preheater pipe system in a temperature range approximately equal to the temperature of the exhaust gas. (2) Cement firing that reduces the concentration of volatile matter circulating between the firing furnace and suspension preheater by extracting a part of the firing furnace exhaust gas from the vicinity of the firing furnace exhaust gas outlet of cement firing equipment equipped with a firing furnace and suspension preheater. In a devolatilization device in a facility, an adsorption tower receives the extracted calciner exhaust gas, a cooling means for cooling or washing the coarse particles sent from the adsorption tower, and a return return for returning the cooled coarse particles from the cooling means to the adsorption tower. means and
It is equipped with a duct that returns the firing furnace exhaust gas after being treated in the adsorption tower to a part of the suspension preheater pipe system in a temperature range that is approximately equal to the exhaust gas temperature. 1. A device for removing volatile matter in cement firing equipment, characterized in that the volatile matter in the exhaust gas of the firing furnace is adsorbed onto the surface of low-temperature coarse grains that are dropped in a continuous manner.