阅读说明：本技术 生产建筑石膏的新型工艺及装备 (Novel process and equipment for producing building gypsum ) 是由 张路 张宏伟 李明 晃阳 王容飞 王连伟 杭琪 王广兴 于 2021-09-30 设计创作，主要内容包括：本发明涉及一种生产建筑石膏的新型工艺及装备,其中生产建筑石膏的新型装备包括一种生产建筑石膏的新型装备,包括进料系统、混料装置、颗粒传热烘干机、螺旋筛和沸腾式煅烧系统,以及与沸腾式煅烧系统连通的除尘系统,还包括连通混料装置与沸腾式煅烧系统的热物料返回系统；颗粒传热烘干机的出料端设有三级蒸汽余热换热装置。本发明通过蒸汽的三级梯度利用,实现生产优质建筑石膏的低温慢烧；减少系统外排湿热空气的热量,符合低碳、节能要求；通过颗粒传热烘干机,冷料和热料高效混合传热,迅速脱除吸附水,杜绝了设备的腐蚀漏气并降低了传动能耗；通过在沸腾炉内的二级慢速煅烧,避免了因过烧而产生无水石膏Ⅲ,提高了建筑石膏品质和稳定性。(The invention relates to a novel process and equipment for producing building gypsum, wherein the novel equipment for producing building gypsum comprises novel equipment for producing building gypsum, a dust removal system and a hot material return system, wherein the novel equipment comprises a feeding system, a mixing device, a particle heat transfer drying machine, a spiral screen, a boiling type calcining system, a dust removal system and a hot material return system, the dust removal system is communicated with the boiling type calcining system, and the hot material return system is communicated with the mixing device and the boiling type calcining system; the discharge end of the particle heat transfer dryer is provided with a three-level steam waste heat exchange device. According to the invention, the low-temperature slow burning for producing high-quality building gypsum is realized through three-level gradient utilization of steam; the heat of the damp and hot air exhausted by the system is reduced, and the requirements of low carbon and energy conservation are met; the cold material and the hot material are efficiently mixed and transfer heat through the particle heat transfer dryer, so that the adsorbed water is quickly removed, the corrosion and air leakage of equipment are avoided, and the transmission energy consumption is reduced; through the secondary slow calcination in the fluidized bed furnace, the anhydrous gypsum III generated by overburning is avoided, and the quality and the stability of the building gypsum are improved.)

1. A novel equipment for producing building gypsum is characterized in that: the material drying device comprises a feeding system, a material mixing device, a particle heat transfer drying machine, a material conveying spiral screen, a boiling type calcining system and a dust removing system communicated with the boiling type calcining system, wherein the feeding system, the material mixing device, the particle heat transfer drying machine, the material conveying spiral screen and the boiling type calcining system are sequentially arranged along the material conveying direction;

the system also comprises a hot material return system for communicating a feed port of the mixing device with the boiling type calcining system;

the particle heat transfer drying machine comprises a rotary drum and a stirring mixing shaft, wherein the rotary drum and the stirring mixing shaft are arranged in a rotating mode, the stirring mixing shaft extends into the rotary drum along the axial direction, a material pushing stirring blade is arranged on the stirring mixing shaft and pushes materials to the discharge end of the rotary drum from the feed end of the rotary drum, and a steam waste heat exchange device for heating the materials is arranged inside the discharge end of the particle heat transfer drying machine.

2. The new plant for the production of construction gypsum according to claim 1, characterized in that: the particle heat transfer drying machine further comprises a feeding box and a discharging box which are fixedly arranged, the feeding box and the discharging box are respectively located at two ends of the rotary drum, rotary holes matched with the rotary drum are respectively formed in the feeding box and the discharging box, a feeding hole of the particle heat transfer drying machine is formed in the feeding box, a discharging hole of the particle heat transfer drying machine is formed in the discharging box, and the steam waste heat exchange device is arranged in the discharging box.

3. The new plant for the production of construction gypsum according to claim 2, characterized in that: and the discharge box is provided with a dust and moisture collecting and exhausting air port communicated with a dust removing system.

4. The new plant for the production of construction gypsum according to claim 2, characterized in that: the boiling type calcining system comprises a first boiling furnace, a second boiling furnace and a steam supply system, wherein the first boiling furnace and the second boiling furnace are sequentially arranged along the material conveying direction and are mutually communicated, a material returning spiral is communicated with the first boiling furnace, heat exchange tubes are arranged in the first boiling furnace and the second boiling furnace, an inlet of each heat exchange tube in the first boiling furnace is communicated with the steam supply system, and an outlet of each heat exchange tube in the first boiling furnace is communicated with an inlet of each heat exchange tube in the second boiling furnace after passing through a steam trap.

5. The novel plant for producing building gypsum according to claim 4, characterized in that: the steam waste heat exchange device comprises a condensate pipe fixedly arranged in the discharge box, an inlet of the condensate pipe is communicated with an outlet of the second fluidized bed boiler after a heat exchange pipe passes through a drain valve, and an outlet of the condensate pipe extends to a water collecting tank of the steam supply system.

6. The new plant for the production of construction gypsum according to claim 1, characterized in that: the discharge hole of the particle heat transfer drying machine is communicated with the feed inlet of the material conveying spiral screen through a first spiral conveyor.

7. The new plant for the production of construction gypsum according to claim 1, characterized in that: the hot material return system comprises a return screw, a return hoister and a second screw conveyor, wherein a feed inlet of the return screw is communicated with the boiling type calcining system, a discharge outlet of the return screw is communicated with a feed inlet of the return hoister, and a discharge outlet of the return hoister is communicated with a feed inlet of the mixing device; the feed inlet of the second screw conveyor is communicated with the discharge port of the dust removal system, and the discharge port of the second screw conveyor is communicated with the feed inlet of the return screw.

8. A novel process for producing building gypsum, comprising the following aspects:

(1) after metering, screening and iron removal, the dihydrate gypsum enters a cooling aging system after sequentially passing through a mixing device, a particle heat transfer dryer, a material conveying spiral sieve and a boiling type calcining system from a feeding system, and the steam provided by a steam supply system provides calcining heat for the boiling type calcining system;

(2) in a first fluidized bed furnace of a fluidized bed calcination system, a newly-fed material is quickly mixed with a hot bed material for heat exchange, a hot bed heat source is high-temperature steam in a heat exchange pipe, and the temperature of the hot bed is 140-150 ℃; under the action of a large amount of water vapor generated by gypsum dehydration and fluidized wind from a Roots blower at the bottom of the equipment, the materials are mixed in a boiling state, and the materials are uniformly dehydrated; part of heated materials flow to the mixing device through the hot material return system, other materials overflow to a second fluidized bed furnace of the calcining system, the materials are slowly calcined through medium-temperature steam after heat exchange in the first fluidized bed furnace, the materials are mixed in a boiling state under the action of a Roots blower, the calcining temperature is 120-130 ℃, the calcining time is 80-120 minutes, semi-hydrated gypsum obtained after slow calcining enters a cooling aging system, and secondary utilization of the steam is realized;

(3) in the mixing device, hot materials flowing from a first fluidized bed furnace are mixed with cold materials introduced by a feeding system, so that the cold materials are preliminarily heated by the hot materials, the mixture of the cold materials and the hot materials is conveyed to a particle heat transfer dryer, and the temperature of the introduced hot materials is 140-150 ℃;

(4) in a particle heat transfer dryer, a stirring mixing shaft and a rotary drum rotate in the same direction to realize the full mixing and heat exchange of cold materials and hot materials, and the cold materials are preheated by the heat of the hot materials, wherein the preheating temperature is 80-90 ℃; in a discharge box of the particle heat transfer dryer, the material is further preheated by using the low-temperature steam after heat exchange in the second fluidized bed furnace, and meanwhile, the third-level utilization of the steam is realized.

Technical Field

The invention relates to the technical field of gypsum production, in particular to a conversion technology from dihydrate gypsum to hemihydrate gypsum, and specifically relates to a novel process and equipment for producing building gypsum.

Background

A large amount of industrial by-product gypsum is dihydrate gypsum containing adsorption water, and usually, hemihydrate gypsum is obtained by heating to remove adsorption water and 1.5 crystal waters, and is used for producing products such as gypsum boards and gypsum mortar, and solid wastes are utilized. At present, when the conversion of dihydrate gypsum to hemihydrate gypsum is carried out, two processes, namely a one-step process and a two-step process, are mainly adopted, wherein the one-step process completes the adsorption of water and 1.5 crystal waters in one device at the same time, and the two-step process completes the removal of the adsorption water in one device first and then removes 1.5 crystal waters in subsequent calcining devices. The one-step process mostly adopts high-temperature hot air as a heat source, and as the absorption water fluctuation of industrial byproduct gypsum is large, the temperature of the heat source is high, partial semi-hydrated gypsum can be converted into anhydrous gypsum in the process of removing absorption water and 1.5 crystal water, the building gypsum produced by the process contains a small amount of dihydrate gypsum and a large amount of anhydrous gypsum, and the anhydrous gypsum has the performances of quick setting and moisture reduction, so that the quality fluctuation of finished products is large and the degree is low. Meanwhile, the process has the advantages of high temperature of externally-exhausted humid air, large air quantity and high energy consumption. The two-step process mostly adopts a low-temperature heat source, firstly uses a dryer to remove the adsorption water, and then uses a calcinator to remove 1.5 crystal waters. Compared with a one-step method, the quality control is optimized, the temperature and the air quantity of externally discharged humid air are reduced, but the equipment maintenance rate of the drying equipment for removing adsorbed water is higher due to corrosion of materials, meanwhile, a low-temperature heat source can only meet secondary utilization, the temperature of externally discharged steam condensate water is higher than 100 ℃, and energy consumption waste is caused.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a novel process and equipment for producing building gypsum, which adopt a real low-temperature slow-burning mode, improve the content of semi-hydrated gypsum in the obtained product, greatly reduce the content of dihydrate gypsum and anhydrous gypsum, ensure the stability of the product, and simultaneously meet the aims of reducing the drying maintenance amount and saving energy of the system.

The invention is realized by the following technical scheme, and provides novel equipment for producing building gypsum, which comprises a feeding metering and conveying system, a mixing device, a particle heat transfer drying machine, a material conveying spiral sieve, a boiling type calcining system and a dust removal system, wherein the feeding metering and conveying system, the mixing device, the particle heat transfer drying machine, the material conveying spiral sieve and the boiling type calcining system are sequentially arranged along the material conveying direction;

the system also comprises a hot material return system for communicating a feed port of the mixing device with the boiling type calcining system;

the particle heat transfer drying machine comprises a rotary drum and a stirring mixing shaft, wherein the rotary drum and the stirring mixing shaft are arranged in a rotating mode, the stirring mixing shaft extends into the rotary drum along the axial direction, a material pushing stirring blade is arranged on the stirring mixing shaft and pushes materials to the discharge end of the rotary drum from the feed end of the rotary drum, and a tertiary steam waste heat exchange device for heating the materials is arranged inside the discharge end of the particle heat transfer drying machine.

When the scheme is used, materials sequentially pass through the material mixing device, the particle heat transfer dryer, the material conveying spiral screen and the boiling type calcining system by the feeding metering conveying system, dust-containing wet air generated during drying and calcining is filtered and separated by the dust removal system, and the discharged wet air meets the environmental protection requirement; by arranging the hot material returning system, part of hot materials of the boiling type calcining system are introduced into the material mixing device, the material mixing device is used for carrying out preliminary mixing heat exchange on cold materials and the hot materials, and the hot materials and the cold materials are fully mixed and heat exchanged through the differential rotation of the rotary cylinder and the stirring shaft to complete uniform drying, so that the uniformity of the heated materials is improved; the dried material is further heated through the steam waste heat exchange device, the material temperature is improved, the temperature of discharged condensed water is reduced, and system energy conservation can be realized. Conversion of hemihydrate gypsum to dihydrate gypsum is also avoided.

As optimization, the particle heat transfer drying machine further comprises a feeding box and a discharging box which are fixedly arranged, the feeding box and the discharging box are respectively located at two ends of the rotary drum, rotary holes matched with the rotary drum are respectively formed in the feeding box and the discharging box, a feeding hole of the particle heat transfer drying machine is formed in the feeding box, a discharging hole of the particle heat transfer drying machine is formed in the discharging box, and the steam waste heat exchange device is arranged in the discharging box. This optimization scheme is through setting up feeding case and ejection of compact case, makes things convenient for the feed inlet and the discharge gate setting of granule heat transfer drying-machine, realizes feeding and the ejection of compact under the revolving drum pivoted condition, also makes things convenient for steam waste heat transfer device's setting simultaneously, sets up steam waste heat transfer device at the ejection of compact case, and the material is very little to heat transfer device's corruption, and the protection maintenance of also being convenient for, material and heat transfer device pass through radiation, conduction and convection heat transfer, have improved heat transfer device's heating effect.

And as optimization, the discharge box is provided with a dust and moisture collecting and exhausting air port communicated with a dust removal system. According to the optimized scheme, the dust collection and moisture discharge port communicated with the dust removal system is arranged, so that dust and moisture enter the dust removal system to be subjected to gas-solid separation, moisture discharge air at the temperature of about 90 ℃ can meet the requirements that a dust remover does not dewfall, the temperature of a filter bag can be reduced, and the service life of the filter bag is prolonged.

As optimization, the boiling type calcining system comprises a first boiling furnace, a second boiling furnace and a steam supply system, wherein the first boiling furnace and the second boiling furnace are sequentially arranged along the material conveying direction and are mutually communicated, the material returning spiral is communicated with the first boiling furnace, steam heat exchange tubes are respectively arranged in the first boiling furnace and the second boiling furnace, an inlet of the steam heat exchange tube in the first boiling furnace is communicated with the steam supply system, and an outlet of the steam heat exchange tube in the first boiling furnace is communicated with an inlet of the steam heat exchange tube in the second boiling furnace after passing through a steam trap. According to the optimized scheme, high-temperature steam is used for calcining the material in the first fluidized bed furnace at a high temperature and a constant speed, one part of the calcined material enters the second fluidized bed furnace, and the other part of the calcined material enters the material mixing device through the hot material return system; the high-temperature steam after heat exchange in the first fluidized bed furnace is changed into condensed water, the condensed water enters a heat exchange pipe of a second fluidized bed furnace after passing through a steam trap, the condensed water is subjected to capacity expansion and steam exposure and is changed into medium-temperature steam, and the materials in the medium-temperature steam are slowly calcined to avoid overburning to generate anhydrous gypsum; the steam is used as a heat source, so that the steam is clean and environment-friendly, secondary utilization of the steam is realized, and more energy is saved.

Preferably, the steam waste heat exchange device comprises a condensate pipe fixedly arranged in the discharge box, an inlet of the condensate pipe is communicated with an outlet of a steam heat exchange pipe in the second fluidized bed boiler, and an outlet of the condensate pipe extends to a water collecting tank of the steam supply system. According to the arrangement of the optimized scheme, the material of the discharge box of the particle heat transfer drying machine is heated by utilizing the low-temperature steam or the condensed water after heat exchange in the second fluidized bed furnace, the third stage utilization of the steam is realized, and the low-carbon and energy-saving effects are further improved.

As optimization, the discharge hole of the particle heat transfer drying machine is communicated with the feed hole of the material conveying spiral screen through the first spiral conveyor, so that the material conveying amount is more conveniently controlled.

As optimization, the hot material return system comprises a return screw, a return hoister and a second screw conveyor, wherein a feed inlet of the return screw is communicated with the boiling type calcining system, a discharge outlet of the return screw is communicated with a feed inlet of the return hoister, and a discharge outlet of the return hoister is communicated with a feed inlet of the mixing device; the feed inlet of the second screw conveyor is communicated with the discharge port of the dust removal system, and the discharge port of the second screw conveyor is communicated with the feed inlet of the return screw. This optimization scheme carries the dust of the partial hot material of boiling formula calcination system and dust pelletizing system separation to the compounding device, has reduced the material waste, more makes things convenient for the arrangement of equipment and returning charge pipeline simultaneously.

The scheme also provides a novel process for producing the building gypsum, which comprises the following aspects:

1. after metering, screening and iron removal, the dihydrate gypsum enters a cooling aging system after sequentially passing through a mixing device, a particle heat transfer dryer, a material conveying spiral sieve and a boiling type calcining system from a feeding system, and the steam provided by a steam supply system provides calcining heat for the boiling type calcining system;

2. in a first fluidized bed furnace of a fluidized bed calcination system, a newly-fed material is quickly mixed with a hot bed material for heat exchange, a hot bed heat source is high-temperature steam in a steam heat exchange pipe, and the temperature of the hot bed is 140-150 ℃; under the action of a large amount of water vapor generated by gypsum dehydration and fluidized wind from a Roots blower at the bottom of the equipment, the materials are mixed in a boiling state, and the materials are uniformly dehydrated; part of heated materials flow to the mixing device through the hot material return system, other materials overflow to a second fluidized bed furnace of the calcining system, the materials are slowly calcined through medium-temperature steam after heat exchange in the first fluidized bed furnace, the materials are mixed in a boiling state under the action of a Roots blower, the calcining temperature is 120-130 ℃, the calcining time is 80-120 minutes, semi-hydrated gypsum obtained after slow calcining enters a cooling aging system, and secondary utilization of the steam is realized;

3. in the mixing device, hot materials flowing from a first fluidized bed furnace are mixed with cold materials introduced by a feeding system, so that the cold materials are preliminarily heated by the hot materials, the mixture of the cold materials and the hot materials is conveyed to a particle heat transfer dryer, and the temperature of the introduced hot materials is 140-150 ℃;

4. in a particle heat transfer dryer, a stirring mixing shaft and a rotary drum rotate in the same direction to realize the full mixing and heat exchange of cold materials and hot materials, and the cold materials are preheated by the heat of the hot materials, wherein the preheating temperature is 80-90 ℃; in a discharge box of the particle heat transfer dryer, the material is further preheated by using the low-temperature steam after heat exchange in the second fluidized bed furnace, and meanwhile, the third-level utilization of the steam is realized.

The invention has the beneficial effects that: preheating, drying and calcining are carried out by using steam to provide heat, and low-temperature slow burning for producing high-quality building gypsum is realized by three-level gradient utilization of the steam; the heat of the damp and hot air exhausted by the system is reduced, and the requirements of low carbon and energy conservation are met; the material passes through the mixing device, so that the temperature and the fluidity of the material are improved; through the particle heat transfer dryer, the cold material and the hot material are efficiently mixed and transfer heat, the adsorption water is rapidly removed, the corrosion and air leakage of the equipment are avoided, and the transmission energy consumption is reduced. Through the secondary slow calcination in the fluidized bed furnace, the anhydrous gypsum III generated by overburning is avoided, and the quality and the stability of the building gypsum are improved.

Drawings

FIG. 1 is a schematic view of the process of the present invention;

FIG. 2 is an enlarged view of the ebullated calcination system of FIG. 1;

FIG. 3 is an enlarged view of the particle heat transfer dryer system of FIG. 1;

FIG. 4 is an enlarged view of a portion of the discharge box of FIG. 3;

FIG. 5 is an enlarged view of the feed system of FIG. 1;

FIG. 6 is an enlarged view of the steam supply system of FIG. 1;

FIG. 7 is an enlarged view of the dust extraction system of FIG. 1;

FIG. 8 is an enlarged view of the hot material return system of FIG. 1;

shown in the figure:

1. the device comprises a rotary drum, 2, a stirring mixing shaft, 3, a mixing device, 4, a first feeding port, 5, a second feeding port, 6, a first screw conveyor, 7, a steam waste heat exchange device, 8, a dust and moisture collecting and discharging port, 9, a discharging box, 10, a material pushing and stirring blade, 11, a low material level meter, 12, an outlet of a condensate pipe, 13, an inlet of the condensate pipe, 14, a high material level meter, 15 and a feeding box.

Detailed Description

In order to clearly illustrate the technical features of the present solution, the present solution is explained below by way of specific embodiments.

Fig. 1 is a novel equipment for producing building gypsum, which comprises a feeding system, a mixing device 3, a particle heat transfer dryer, a material conveying spiral screen, a boiling type calcining system, a hot material returning system and a dust removing system, wherein the feeding system, the mixing device 3, the particle heat transfer dryer, the material conveying spiral screen and the boiling type calcining system are sequentially arranged along the material conveying direction, the hot material returning system and the dust removing system are communicated with the boiling type calcining system, the feeding system is a feeding metering conveying system with metering and conveying functions, and the hot material returning system is communicated with a feeding hole of the mixing device and the boiling type calcining system. The discharge end of the feeding system corresponds to the feed inlet of the mixing device, the discharge port of the mixing device corresponds to the feed inlet of the particle heat transfer drying machine, the discharge port of the particle heat transfer drying machine corresponds to the feed inlet of the material conveying spiral screen, the discharge port of the material conveying spiral screen corresponds to the feed inlet of the boiling type calcining system, materials sequentially pass through the mixing device, the particle heat transfer drying machine and the material conveying spiral screen from the feeding system and then enter the boiling type calcining system, and the materials calcined by the boiling type calcining system enter the cooling and aging system for cooling.

The hot material return system comprises a return screw, a return hoister and a second screw conveyor, wherein a feed inlet of the return screw is communicated with a first fluidized bed furnace of the fluidized bed calcining system through a return valve, a discharge outlet of the return screw is communicated with a feed inlet of the return hoister, and a discharge outlet of the return hoister is communicated with a feed inlet of the mixing device; the feed inlet of the second screw conveyor is communicated with the discharge port of the dust removal system, and the discharge port of the second screw conveyor is communicated with the feed inlet of the return screw. Part of hot materials in the first fluidized bed furnace enter the mixing device 3 through a return material screw and a return material elevator. The compounding device 3 of this embodiment is biax spiral blendor, improves the compounding effect, and first pan feeding mouth 4 and second pan feeding mouth 5 have been seted up at the top of compounding device, and the material that feed system carried is accepted to first pan feeding mouth 4, and the material that the material return elevator was carried is accepted to second pan feeding mouth 5.

This embodiment adopts heat-retaining bed granule heat transfer technique, mixes cold burden and hot material through granule heat transfer drying-machine, realizes the stoving to the material. Specifically, granule heat transfer drying-machine is including fixed feeding case 15 and the play workbin 9 that sets up, and the rotary drum 1 and the stirring mixing shaft 2 that rotate the setting, the feeding case, the play workbin is located the both ends of rotary drum respectively, and set up respectively on feeding case and play workbin with the gyration hole of rotary drum adaptation, rotary drum and the stirring mixing shaft turn to unanimously, speed is adjustable respectively, lean on the poor adjustment material velocity of flow of speed, the stirring mixing shaft extends to in the rotary drum along the axial, and install on the stirring mixing shaft and push away material stirring vane 10 of pushing the material to the rotary drum discharge end by the feed end of rotary drum to the material, the inside steam waste heat transfer device 7 that is equipped with the heating material of discharge end of granule heat transfer drying-machine. The feed inlet of granule heat transfer drying-machine sets up at feeding case top, and the discharge gate of granule heat transfer drying-machine sets up in ejection of compact incasement portion, and the top of ejection of compact case is equipped with the moisture wind gap 8 of row that gathers dust that communicates with dust pelletizing system, and the power of row's moisture comes from dust pelletizing system's draught fan. Install high charge level indicator 14 and low charge level indicator 11 on the lateral wall of ejection of compact case for detect out the high, low material level of material in the workbin, avoid appearing the material too much or lack the material, guarantee that production goes on smoothly.

The material is in compounding device, granule heat transfer drying-machine, mainly utilize the constant speed to calcine the hot material (mainly with half water gypsum, contain some dihydrate gypsum) of about 150 ℃ of section and transfer heat to the raw materials, the granule heat transfer is more rapid, can improve the mobility and the temperature of the material fast, at this stage, the material principal ingredients are half water gypsum and dihydrate gypsum still, only the hot half water gypsum is because of heat transfer cooling, no longer continue to take off the crystal water.

The steam waste heat exchange device 7 is arranged in the discharge box, the steam waste heat exchange device 7 comprises a condensate pipe fixedly arranged in the discharge box, an inlet 13 of the condensate pipe is communicated with an outlet of a steam heat exchange coil in the second fluidized bed furnace, and an outlet 12 of the condensate pipe extends to a water collecting tank of the steam supply system.

The boiling type calcining system comprises a first boiling furnace and a second boiling furnace which are sequentially arranged along the material conveying direction and are mutually communicated, and a steam supply system, wherein a material returning spiral is communicated with the first boiling furnace through a material returning valve, steam heat exchange coils are arranged in the first boiling furnace and the second boiling furnace, an inlet of the steam heat exchange coil in the first boiling furnace is communicated with the steam supply system, and an outlet of the steam heat exchange coil in the first boiling furnace is communicated with an inlet of the steam heat exchange coil in the second boiling furnace after passing through a steam trap. The upper gas collecting boxes in the first fluidized bed furnace and the second fluidized bed furnace are provided with heat exchangers, natural air in a pipe pass is heated by utilizing wet air at about 150 ℃ discharged by calcined gypsum, and the heated air enters a Roots blower at the lower part of the calcining system.

The discharge hole of the particle heat transfer drying machine is communicated with the feed inlet of the material conveying spiral screen through a first spiral conveyor. Specifically, the feed inlet of the first screw conveyer corresponds to the discharge outlet of the particle heat transfer dryer, the feed inlet of the screw sieve at the discharge outlet of the first screw conveyer corresponds to the discharge outlet of the boiling type calcining system, and a breaker can be arranged to break particles.

A novel process for producing building gypsum using the apparatus of this example includes the following:

1. after metering, screening and iron removal, the dihydrate gypsum enters a cooling and aging system after sequentially passing through a mixing device, a particle heat transfer dryer, a material conveying spiral sieve and a boiling type calcining system from a feeding system, and the steam provided by a steam supply system provides calcining heat for the boiling type calcining system.

2. Calcining at a constant speed in a first fluidized bed furnace of a fluidized bed calcining system, rapidly mixing and exchanging heat between a newly-fed material and a hot bed material, wherein a hot bed heat source is high-temperature steam in a steam heat exchange pipe, and the temperature of the hot bed is 140-150 ℃; under the action of a large amount of water vapor generated by gypsum dehydration and fluidized wind from a Roots blower at the bottom of the equipment, the materials are mixed in a boiling state, and the materials are uniformly dehydrated; part of heated materials flow to the mixing device through the hot material return system, other materials overflow to a second fluidized bed furnace of the calcining system, the materials are slowly calcined through medium-temperature steam after heat exchange in the first fluidized bed furnace, the materials are mixed in a boiling state under the action of a Roots blower, the calcining temperature is 120-130 ℃, the calcining time is 80-120 minutes, semi-hydrated gypsum obtained after slow calcining enters a cooling aging system, and secondary utilization of the steam is realized; the constant-speed calcination section has the material temperature of 140-; in the slow calcining stage, the materials are basically semi-hydrated gypsum and a small amount of residual dihydrate gypsum, and in the stage, the residual heat after steam expansion and steam exposure is used for continuously supplying dehydration reaction to the materials, and the semi-hydrated gypsum is not continuously dehydrated to generate anhydrous gypsum III due to high temperature.

Constant-speed calcination and slow-speed calcination refer to the difference of dehydration rates, which is related to the dehydration temperature, and the temperature of the material bed can be adjusted by controlling the steam pressure and flow in the heat exchange bed. The steam pressure for constant-speed calcination is high, the condensed water or medium-temperature steam after constant-speed calcination acting is used for slow-speed calcination, the temperature of the material bed is low, and the dehydration rate of the gypsum is greatly reduced. The dehydration time and the heat exchange amount of the gypsum are determined by the heat exchange volume and the heat exchange area of the calcining equipment, so that the fluidized bed furnace of the constant-speed and slow-speed calcining section needs to be designed and manufactured according to the dehydration time and the heat exchange amount of the process design.

3. In the mixing device, hot materials flowing into the first fluidized bed furnace are mixed with cold materials introduced into the feeding system, so that the cold materials are preliminarily heated by the hot materials, the mixture of the cold materials and the hot materials is conveyed to the particle heat transfer drying machine, and the temperature of the introduced hot materials is 140-150 ℃.

4. In a particle heat transfer dryer, a stirring mixing shaft and a rotary drum rotate in the same direction to realize the full mixing and heat exchange of cold materials and hot materials, and the cold materials are preheated by the heat of the hot materials, wherein the preheating temperature is 80-90 ℃; in a discharge box of the particle heat transfer dryer, the material is further preheated by using the low-temperature steam after heat exchange in the second fluidized bed furnace, and meanwhile, the third-level utilization of the steam is realized.

5. Steam supply system's steam comes from power plant's steam pipe network, and the condensate water after the steam waste heat transfer device heat transfer flows to the catch basin, carries to the power plant or is used for heating, takeaway by the catch basin.

The dihydrate gypsum is dehydrated within the range of 130-170 ℃, the hemihydrate gypsum is basically used as the main component, the temperature is low, the dehydration rate is low, and the higher the temperature is, the faster the dehydration rate is; proper dehydration time and dehydration temperature are important means for controlling the content of the hemihydrate gypsum. According to the process and the equipment, the adsorption water removal of the gypsum is completed through the mixing device and the particle heat transfer dryer, and the dried hot materials are basically dihydrate gypsum and hemihydrate gypsum because the material temperature is less than 90 ℃; the material enters a boiling type calcining system, the boiling type calcining system is a fluidized bed with two-stage steam heat exchange, the material firstly enters a first-stage steam heat exchange fluidized bed of a first boiling furnace, and exchanges heat with bed heat quickly to reach the temperature (about 150 ℃) for quick dehydration, and the temperature of a heat exchange bed can be adjusted by adjusting the steam flow through the heat evaporation of steam in the partial heat exchange. The material flows through the first-stage heat exchange bed and then enters the second-stage heat exchange bed of the second fluidized bed furnace, the steam of the bed is the secondary utilization of the condensed water from the first-stage fluidized bed heat exchanger through the steam trap (saving steam) for expanding and aerating, the vaporized heat is transferred to the fluidized bed material, the material temperature is 120-130 ℃, the residual dihydrate gypsum can be fully converted into the hemihydrate gypsum at the temperature, and the hemihydrate gypsum can not be converted into the anhydrite III due to long dehydration time.

Of course, the above description is not limited to the above examples, and the undescribed technical features of the present invention can be implemented by or using the prior art, and will not be described herein again; the above embodiments and drawings are only for illustrating the technical solutions of the present invention and not for limiting the present invention, and the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that changes, modifications, additions or substitutions within the spirit and scope of the present invention may be made by those skilled in the art without departing from the spirit of the present invention, and shall also fall within the scope of the claims of the present invention.