CN1718556A

CN1718556A - Predecomposition kiln by pass air relief and coal gangue dewatering technology

Info

Publication number: CN1718556A
Application number: CNA2004100123934A
Authority: CN
Inventors: 杨克锐; 张彩文
Original assignee: Hebei University of Science and Technology
Current assignee: Hebei University of Technology; Hebei University of Science and Technology
Priority date: 2004-07-09
Filing date: 2004-07-09
Publication date: 2006-01-11
Anticipated expiration: 2024-07-09
Also published as: CN1312070C

Abstract

A process for dewatering the coal gangue by the discharged hot fume of predecomposing kiln includes such steps as introducing said hot fume to preheating-dewatering pipe, introducing cold air for cooling it to proper temp, adding coal gangue powder, thermally converting the kaolin in coal gangue powder to metakaolin, stage-one cyclone separation for separating dewatered coal gangue powder from fume, cooling the powder, stage-two cyclone separation to obtain product, introducing the fume to moistening tower, moistening, electric dusting, and exhausting the air.

Description

Predecomposition kiln bypass air release and coal gangue dehydrationprocess

Technical Field

The invention relates to a coal gangue dehydration process, in particular to a predecomposition kiln bypass air release and coal gangue dehydration process.

Background

The precalciner kiln is the most advanced cement calcining equipment in the world at present and is also the leading kiln type of the key development in China at present. However, with the rapid consumption of mineral resources for cement production in our country, the quality raw materials are gradually reduced, and the harmful elements such as alkali, chlorine, sulfur and the like in the cement raw materials are continuously improved, so that the calcining conditions in the kiln are gradually worsened, the quality of clinker and cement is reduced, and even the alkali-aggregate reaction of concrete is caused, thereby causing serious engineering accidents. On the other hand, the cement industry is an industrial sector consuming a large amount of raw materials and energy, and the development goal of the cement industry in this century is to realize greenization and high performance according to the national sustainable development strategy. The key point is to save resources and energy, and one of the important measures is to use a large amount of industrial waste residues for cement production. The coal gangue is the industrial waste residue with the largest discharge amount and the lowest utilization rate at present. The main reason for low utilization rate is that the volcanic ash activity of the spontaneous combustion coal gangue is too low, so the most important measure is to improve the volcanic ash activity of the coal gangue to improve the utilization rate of the coal gangue.

Disclosure of Invention

The invention aims to provide a predecomposition kiln bypass air release and coal gangue dehydration process which can perform coal gangue dehydration while performing bypass air release of a predecomposition kiln, effectively reduce the content of harmful elements in materials in the predecomposition kiln by utilizing the high-temperature environment of the bypass air release and greatly improve the activity of volcanic ash of the predecomposition kiln.

The technical scheme for realizing the aim of the invention is as follows: the coal gangue dehydration process is carried out according to the following steps that a, hot flue gas with the temperature of about 1000 ℃ is led out from the pre-decomposition kiln and enters a pre-heating dehydration pipe 1, and then is led into a primary cyclone separator 2 through the pre-heating dehydration pipe 1; b. in the dehydration tube 1, opening the electric valve L to introduce cold air so that the temperature of the dehydration tube 1 reaches the dehydration temperature of the coal gangue; c. adding the coal gangue powder into the preheating dehydration pipe 1, and removing free water and removing crystals from the mineral kaolinite of the coal gangue powder under the action of hot flue gas to obtain metakaolinite; d. the dehydrated product and the high alkali kiln dust led out from the kiln tail are mixed with the airflow and enter a first-stage cyclone separator 2 for gas-solid separation; e. the dehydrated coal gangue powder from the primary cyclone separator 2 enters a cooling pipe from a feed opening, is cooled and then enters a secondary cyclone separator 3, and the temperature of the coal gangue powder passing through the secondary cyclone separators 3 and 4 is 65-70 ℃, so that a finished product is obtained; f. and introducing the waste gas discharged from the primary cyclone separator 2 into a humidifying tower 7 for humidifying, and discharging the gas after dust is collected by an electric dust collector, wherein the dust is a product.

By adopting the process, the alkali content of the materials in the kiln can be effectively reduced, the safe operation of the kiln is ensured, and the quality of clinker and cement is improved. And can also obtain a high-quality cement admixture or concrete admixture. The mixed material has high specific surface area and the characteristic of silica fume, so that the mixed material can exert various effects, improve the construction performance of concrete and improve the durability of the concrete. The process has low power consumption and no influence on the kiln.

Drawings

FIG. 1 is a schematic process flow diagram of the present invention.

FIG. 2 is a schematic diagram of a 4-unit cooling process according to the present invention.

Detailed Description

The invention is further described with reference to the following figures and examples. Referring to fig. 1, the invention comprises two parts, namely a predecomposition kiln consisting of a rotary kiln 12 and a decomposition kiln 13, and a coal gangue dehydration device for coal gangue dehydration consisting of a preheating dehydration pipe and a cyclone separator. The coal gangue dehydration process is carried out according to the following steps,

1. dewatering by induced air

Firstly, hot flue gas with the temperature of about 1000 ℃ is led out from the position 11 with the highest content of harmful elements in the pre-decomposition kiln, the hot flue gas is led into a preheating and dehydrating pipe 1, and the hot flue gas enters a primary cyclone separator 2 through the preheating and dehydrating pipe 1. In order to adjust the temperature, an electric valve L is additionally arranged in the dehydration tube 1, the electric valve L is opened to introduce cold air or introduce hot air from a tertiary air pipe of the pre-decomposition kiln, so that the temperature of the dehydration tube 1 reaches the dehydration temperature of the coal gangue of 850 ℃, and air required by combustible combustion is met, thereby being suitable for the dehydration requirement of the coal gangue. Meanwhile, coal gangue powder which is ground and has the fineness of 0.08mm and the screen residue of which is 10 to 15 percent is added from the M part of the preheating dehydration pipe 1, volatile matters and fixed carbon of the coal gangue are combusted under the action of hot flue gas, and free water and crystal water are removed from main mineral kaolinite to form metakaolinite. The reaction formula is as follows:

other minerals are also changed correspondingly to be in an activated state. Meanwhile, the gangue powder absorbs harmful elements such as chlorine, sulfur, alkali and the like in the flue gas in the contact of the flue gas, so that the content of the harmful elements in the flue gas is greatly reduced.

The dehydrated products and high-alkali kiln dust led out from the kiln tail are mixed with airflow and enter a primary cyclone separator 2, and gas-solid separation is carried out in the primary cyclone separator 2.

The dehydrated coal gangue powder from the primary cyclone separator 2 has the temperature of 800 ℃, enters a cooling pipe from a feed opening, enters the second and third cyclone separators 3 and 4 after being cooled by cold air sucked in a workshop, and has the temperature of 65-70 ℃ after passingthrough the second and third cyclone separators 3 and 4 to obtain a finished product. The finished products are sent to a coal gangue warehouse for storage through a single bin pump 6, and part of the products are collected by a dust collector.

2. Treating exhaust gases

Example 1, as shown in fig. 1, the exhaust gas from the primary cyclone 2 was directly introduced into a quench chamber, sprayed with water and mixed with cold air, and then introduced into an electric precipitator after the temperature was reduced. The waste gas from the secondary and tertiary cyclone separators 3 and 4, namely the gangue powder cooling system, has the temperature of about 150 ℃, and can be directly used for grinding and drying the gangue.

Example 2: as shown in fig. 2, the exhaust gas discharged from the primary cyclone separator 2 is introduced into a humidifying tower 7, humidified, then collected by an electric dust collector 8, and then discharged by a smoke exhaust fan 9 and a chimney 10.

Example 3: as shown in FIG. 2, the exhaust gas from the primary cyclone 2 directly enters the cyclone connecting pipes of 14 to 15 stages of the decomposing kiln and then enters the preheater system of the pre-decomposing kiln again.

The invention can also be used for the hot gas of the predecomposition kiln grate cooler, and other hot gases can also be used.

Claims

1. A process for the by-pass ventilation and coal gangue dehydration of a pre-decomposition kiln comprises a rotary kiln and a decomposition kiln connected with the rotary kiln, and is characterized by also comprising a coal gangue dehydration device which is used for coal gangue dehydration and consists of a preheating dehydration pipe and a cyclone separator, wherein the coal gangue dehydration process is carried out according to the following steps,

a. firstly, hot flue gas is led out from a predecomposition kiln, enters a preheating dehydration pipe (1), and is led into a first-stage cyclone separator (2) through the preheating dehydration pipe (1);

b. in the dehydration tube (1), opening the electric valve L to introduce cold air so that the temperature of the dehydration tube (1) reaches the dehydration temperature of the coal gangue and provide air required by combustion of combustible substances of the coal gangue;

c. adding the gangue powder into a preheating dehydration pipe (1), quickly removing free water and crystal water from kaolinite which is a leading mineral of the gangue powder under the action of hot flue gas to form metakaolin, and absorbing harmful substances in air flow;

d. the dehydrated product and the high alkali kiln dust led out from the kiln tail are mixed with the airflow and enter a first-stage cyclone separator (2) for gas-solid separation;

e. the dehydrated coal gangue powder from the primary cyclone separator (2) enters a cooling pipe from a feed opening, is cooled and then enters a secondary cyclone separator (3), and the temperature of the coal gangue powder passing through the secondary cyclone separators (3) and (4) is 65-70 ℃, so that a finished product is obtained;

f. and introducing waste gas discharged from the primary cyclone separator (2) into a humidifying tower (7) for humidifying, and discharging the gas after dust is collected by an electric dust collector, wherein the collected dust is a product.

2. The process for the by-pass ventilation and coal gangue dehydration of the pre-decomposition kiln as claimed in claim 1, wherein the exhaust gas from the primary cyclone 2 is directly introduced into the cyclone connecting pipes of 14 to 15 stages of the decomposition kiln, and the gas flow is returned to the preheater of the pre-decomposition kiln.