CN111517681A

CN111517681A - Gypsum cooling and aging process

Info

Publication number: CN111517681A
Application number: CN202010307045.9A
Authority: CN
Inventors: 姜小鹏; 张云波; 唐晓娜; 谢蕾; 刘元会
Original assignee: Qingdao Quantum Yuanji Environmental Protection Technology Co ltd
Current assignee: Qingdao Quantum Yuanji Environmental Protection Technology Co ltd
Priority date: 2020-04-17
Filing date: 2020-04-17
Publication date: 2020-08-11

Abstract

The invention discloses a cooling and aging process for gypsum, which comprises the following steps: (1) quantitatively conveying the high-temperature building gypsum raw material containing soluble anhydrous calcium sulfate to a cooling chamber; (2) cold air is supplied to the cooling chamber to play a role of cooling, gas-solid mixing is carried out in the cooling chamber to generate a gas-solid mixture, meanwhile, water mist and the cold air are input to the evaporation chamber, and gaseous wet hot air flow is generated under the action of heat exchange between liquid water in the evaporation chamber and the cooling chamber; (3) the gas-solid mixture and warm air flow enter an aging chamber to carry out gas-liquid-solid three-phase mixing aging reaction, and secondary gas-solid mixing temperature reduction is carried out, part of heat of the material to be cooled is used for evaporating liquid water by fully utilizing the heat of the hot material, and a large amount of latent heat of vaporization is needed for evaporating the liquid water to absorb the heat of part of the material, so that the temperature reduction effect is realized; meanwhile, the evaporated liquid water is in direct contact with the materials in a water vapor mode, so that the conditions of adhesion, non-uniform aging and the like caused by direct contact of liquid fog drops and the materials are avoided, and the using amount of wet air is reduced.

Description

Gypsum cooling and aging process

Technical Field

The invention belongs to the field of building material preparation, and particularly relates to a process for quickly cooling and aging calcined building gypsum, in particular to a process for quickly cooling and aging building gypsum with high content of soluble anhydrous calcium sulfate.

Background

The production of building gypsum powder is a process of calcining dihydrate gypsum (DH) into hemihydrate gypsum (HH). In order to increase the conversion of hemihydrate gypsum, there must be some degree of overburning, so that the calcination process is accompanied by the formation of some amount of soluble Anhydrite (AIII) and insoluble Anhydrite (AIII). Therefore, the calcined product is composed of hemihydrate gypsum, soluble anhydrite, insoluble anhydrite, and a small amount of unreacted dihydrate gypsum and impurities.

The most significant factor affecting product performance is the content of hemihydrate, dihydrate and soluble anhydrite. Wherein, the hemihydrate gypsum is the main effective component, and the higher the content is, the better the content is; the dihydrate gypsum belongs to unreacted materials, and the content is as low as possible; too high a soluble anhydrite content can result in short setting times for the product, unstable formulations for downstream applications, reduced setting strength, and the like. Must be aged to allow the soluble anhydrite to combine with the water vapor and react to form hemihydrate gypsum, reducing or eliminating the content of the soluble anhydrite. After the building gypsum is aged, performance indexes such as standard thickness, setting time, strength and the like of the building gypsum are obviously improved.

The aging is mainly divided into natural aging and forced aging, the natural aging period is long, and the natural stacking time is more than 7 days; in addition, the discharging temperature of calcined building gypsum is usually over 140 ℃, and the building gypsum needs to be cooled and then packaged, so that stacked products occupy a large amount of sites and storage equipment, and the production period of the materials is greatly prolonged. The natural cooling aging mode is gradually replaced by the industrialized technical scheme.

The existing forced cooling and aging technical scheme mainly adopts two forms of pneumatic conveying and mechanical bin dumping, and although the two forms can also realize the functions of cooling and aging, the heat of materials is completely released and wasted, and a large amount of cold air is needed for heat exchange and steam supply, so that higher equipment and energy consumption investment are needed. Especially for high temperature, high AIII content materials, the energy consumption is multiplied. Particularly, for areas with dry inland climate, the energy consumption for aging is obviously higher than that of coastal river areas.

The technical principle of the temperature reduction and aging of the calcined building gypsum is as follows: the cooling can be realized by forcibly mixing cold air and hot materials; aging requires mixing, contacting and reacting AIII with water vapor in humid air. However, the existing technical scheme only simply utilizes the principles to solve the problems, and still has the problems of large equipment investment, low utilization rate, high energy consumption and the like. The main reasons are that: the moisture content of the air in the environment is relatively low, influenced by temperature and relative humidity, generally less than 1%, providing the same mass of water vapour, the lower the moisture content the more air is required.

Disclosure of Invention

The invention aims to solve the technical problem of providing a gypsum cooling and aging process which effectively utilizes waste heat, reduces unit energy consumption and equipment investment, and particularly organically integrates cooling and aging.

In order to achieve the purpose, the invention adopts the technical scheme that: a cooling and aging process for gypsum is characterized by comprising the following steps: (1) the high-temperature building gypsum raw material containing soluble anhydrous calcium sulfate discharged from the calcining furnace is quantitatively conveyed to a cooling chamber by a conveyor; (2) cold air is supplied to the cooling chamber to play a role of cooling, gas-solid mixing is carried out in the cooling chamber to generate a gas-solid mixture, meanwhile, water mist and the cold air are input to the evaporation chamber, and gaseous wet hot air flow is generated under the action of heat exchange between liquid water in the evaporation chamber and the cooling chamber; (3) the gas-solid mixture and the damp-heat airflow enter an aging chamber for aging reaction, and the secondary gas-solid mixture is cooled.

Further, the gas-liquid-solid three-phase material and the mixture thereof travel under the drainage of negative pressure air.

Further, the cooling chamber cools the high-temperature gypsum raw material to 80-110 ℃.

Further, the temperature of the aged gypsum after the aging reaction and mixing is reduced to 60-90 ℃.

Further, after the step (3), a gas-solid separator is used for separating the finished aged gypsum, and tail gas is purified by a dust removal device and then discharged into the atmosphere.

Furthermore, a dividing wall type heat exchange mode is adopted between the cooling chamber and the evaporation chamber, and the evaporation cooling and the humidification of the mixed humidification are organically combined.

Further, the calcined material is firstly stored in a buffer bin and then quantitatively conveyed to a cooling chamber by a conveyor.

Furthermore, the cooling chamber and the evaporation chamber independently supply air.

By implementing the technical scheme of the invention, the heat of the hot material is fully utilized, and the partial heat of the material needing to be cooled is used for evaporating liquid water, so that the moisture content in the air is multiplied, and the amount of the air needed by aging of the unit material is reduced. The evaporation of the liquid water needs a large amount of latent heat of vaporization, and the heat of a part of materials can be absorbed to carry out primary heat absorption on hot materials; and meanwhile, the wet air is mixed with the hot materials, so that the materials can be further cooled, and a dual cooling effect is realized. The method realizes the miniaturization of equipment and reduces the unit energy consumption of products by organically integrating the cooling and the aging.

The main principle of the invention is that high-temperature materials are utilized to transfer heat through the dividing wall type of the evaporation chamber, water mist in the evaporation chamber is vaporized under the action of wind, vaporized water vapor is driven by the wind to rise and cross the top of the evaporation chamber to be in contact with the materials for mixing, and the materials are aged.

According to the invention, for the materials with high AIII content, the water vapor required by aging of the materials with different AIII contents can be met only by adjusting the evaporation capacity of the water mist, and the power of pneumatic equipment is not required to be increased. The interrelationship of the material, gas and evaporated water is determined according to the material temperature and the AIII content, and heat balance and material balance matching calculation are required. The heat exchange limit and other limiting conditions are involved, and the proportion is not simply selected.

The invention not only has the advantages of large-scale continuous automatic production and the like, but also can utilize waste heat, and greatly reduce the unit energy consumption, equipment cost investment and site occupation of the prior art.

Drawings

FIG. 1 is a schematic block diagram of a cooling and aging process for gypsum.

Detailed Description

The following further describes embodiments of the present invention with reference to the drawings. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

As shown in figure 1, the gypsum cooling and aging process is realized by a cooling and aging device which comprises a cooling chamber, an evaporation chamber and an aging chamber.

The cooling and aging process of the gypsum comprises the following steps:

1. detecting a gypsum product produced by the stably-produced calcining furnace, and knowing the material temperature and the three-phase content of the gypsum product; and (4) carrying out material balance and heat balance, and matching the feeding quantity, the air quantity and the evaporation quantity. Setting equipment parameters and starting the fan, the feeding equipment and the spraying system in sequence.

2. The materials are conveyed to a buffer bin to store a certain amount of materials, and after the materials are discharged from the buffer bin, the materials are conveyed to a cooling chamber of a cooling and ageing device through a quantitative conveyor, and the powder materials are sucked into equipment under the action of negative pressure air.

3. Meanwhile, cold air required for aging is supplied from the air inlet, sufficient gas-solid mixing is carried out in the cooling chamber, the temperature of the mixed gas-solid mixed phase is about below 110 ℃ to carry out primary cooling on the materials.

4. An independent evaporation chamber is arranged in the cooling and aging device, the evaporation chamber is isolated from the cooling chamber through a pipe wall, and outlets at the upper ends of the two chambers are communicated with each other. Spraying water mist in the evaporation chamber, enabling the water mist to move upwards under the drive of cold air, exchanging heat with the tube wall of the evaporation chamber in the process, conducting heat transfer and evaporation by utilizing the heat of the material, enabling the hot and humid airflow after evaporation and temperature reduction to synchronously enter an aging chamber with the gas-solid mixture in the temperature reduction chamber at the top end of the evaporation chamber, carrying out aging reaction on the material AIII phase, and further reducing the temperature of the material to be below 90 ℃.

5. The treated material is separated from air by a gas-solid separator, the powder material is collected in a finished product bin for storage, tail gas is purified by a dust removal device and is discharged into the atmosphere after reaching the standard, and the material after dust collection also enters the finished product bin.

In order to express the invention more clearly, the production process of the invention method is described in detail below with reference to specific parameters, the parameters embodied in the case are only used for illustrating the production process, the same raw material parameters can embody different process parameters through matching of different process air and process water, but the effect of temperature reduction and aging can still be realized, and the following embodiments are specifically provided:

the cooling aging device matches the air volume ratio of the cooling chamber and the evaporation chamber according to the above incoming material parameters (the output of the calcining furnace is 14t/h, the discharging temperature of the calcining furnace is 140 ℃, the AIII content is 15%, DH 3%, HH 77%, and impurities are 5%,) and the total air volume of the system is 15000m³And h, enabling the whole system to be in a micro negative pressure state.

The material produced by the calcining furnace enters a system buffer bin as the feeding material of the method, and the material in the buffer bin is quantitatively conveyed to a cooling chamber of a cooling aging device through a conveyor (the heat required by material cooling is 9.24 × 10)⁵kj/h), simultaneously spraying fine water mist in the evaporation chamber according to ageing, wherein the amount of water required by the evaporation and ageing is 138.97kg/h, and the evaporation heat is 3.46 × 10⁵kj/h (about 37.5%) was derived from the hot mass in the cold room. The water evaporation absorbs the heat of the material and provides the required water vapor for aging. The evaporated hot and humid air and the material gas mixed air flow of the temperature reduction chamber enter the aging chamber simultaneously for aging reaction under the action of the negative pressure air flow.

The two flows in the aging chamber are further mixed for heat exchange, and simultaneously, the water vapor in the air rapidly enters the powder material to perform an aging reaction with AIII.

And separating the material gas mixed gas flow after reaction by using a separating device, collecting the material in a finished product bin, purifying tail gas by using a dust removal device, discharging the purified air into the atmosphere after the purified air reaches the standard, detecting the collected dust material, and sending the qualified dust material into the finished product bin.

At the moment, the material temperature of the finished product bin is reduced to be below 80 ℃, and the content of AIII is aged to meet the production requirement.

According to the embodiment, compared with the full air cooling process, the energy-saving consumption-reducing effect is generally over 35%, and the higher the content of the material AIII is, the better the energy-saving consumption-reducing effect is. Compared with the cooling and aging processes of mechanical dumping, suspension and the like, the unit energy consumption related by the invention is only one fraction or one tenth of the former. The invention has the advantages that the finished product keeps the DH content basically stable, and the AIII content is 0-3%.

The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. It will be apparent to those skilled in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, and the scope of protection is still within the scope of the invention.

Claims

1. A cooling and aging process for gypsum is characterized by comprising the following steps:

(1) the high-temperature building gypsum raw material containing soluble anhydrous calcium sulfate discharged from the calcining furnace is quantitatively conveyed to a cooling chamber by a conveyor;

(2) cold air is supplied to the cooling chamber to play a role of cooling, gas-solid mixing is carried out in the cooling chamber to generate a gas-solid mixture, meanwhile, water mist and the cold air are input to the evaporation chamber, and gaseous wet hot air flow is generated under the action of heat exchange between liquid water in the evaporation chamber and the cooling chamber;

(3) the gas-solid mixture and the damp-hot airflow enter an aging chamber to carry out gas-liquid-solid three-phase mixed aging reaction, and secondary gas-solid mixed cooling is carried out.

2. The cooling aging process for gypsum according to claim 1, wherein: the gas-liquid-solid three-phase material and the mixture thereof advance under the drainage of negative pressure air.

3. The cooling aging process for gypsum according to claim 1, wherein: the cooling chamber cools the high-temperature gypsum raw material to 80-110 ℃.

4. The cooling aging process for gypsum according to claim 1, wherein: the temperature of the aged gypsum after the aging reaction and mixing is reduced to 60-90 ℃.

5. The cooling aging process for gypsum according to claim 1, wherein: and after the step 3, separating the aged gypsum finished product by using a gas-solid separator, and discharging the tail gas into the atmosphere after the tail gas is purified by a dust removal device.

6. The cooling aging process for gypsum according to claim 1, wherein: and a dividing wall type heat exchange mode is adopted between the cooling chamber and the evaporation chamber, and the evaporation cooling and humidification of mixed humidification are organically combined.

7. The cooling aging process for gypsum according to claim 1, characterized in that: the calcined material is firstly stored in a buffer bin and then quantitatively conveyed to a cooling chamber by a conveyor.

8. The cooling aging process for gypsum according to claim 1, characterized in that: the cooling chamber and the evaporation chamber independently supply air.