阅读说明：本技术 一种离心工序饱和蒸汽代替水洗晶体方法 (Method for replacing water washing crystal with saturated steam in centrifugal process ) 是由 韩承勇 韩先卓 钟礼杰 刘峰 于 2020-12-28 设计创作，主要内容包括：本发明公开了一种离心工序饱和蒸汽代替水洗晶体方法,包括步骤：(1)在立式结晶釜内泵入糖醇溶液进行蒸发,蒸发至折光后放料进入卧式结晶槽,进行降温结晶；(2)降温结晶后得到离心前的晶体和母液的混合溶液,混合溶液在卧式结晶槽中保温；(3)混合溶液移至离心机进行离心,然后开启饱和蒸汽阀门,使用饱和蒸汽对晶体进行吹洗,观察母液管道是否有母液流出,如果没有液体流出,即可停止吹洗；(4)停止蒸汽吹洗,刮刀刮料进入冷却工序,使用振动流化床对吹洗干净后的高温晶体进行降温,得到晶体。本发明使用饱和蒸汽对晶体进行吹洗,蒸汽温度低于结晶体熔点,那么无论怎样吹洗,晶体都没有损耗,而且收率会有提高。(The invention discloses a method for replacing water washing crystals with saturated steam in a centrifugal process, which comprises the following steps: (1) pumping sugar alcohol solution into a vertical crystallization kettle for evaporation, discharging the material after the evaporation is carried out until the refraction, and then feeding the material into a horizontal crystallization tank for cooling crystallization; (2) cooling and crystallizing to obtain a mixed solution of crystals and mother liquor before centrifugation, and keeping the temperature of the mixed solution in a horizontal crystallizing tank; (3) the mixed solution is moved to a centrifuge for centrifugation, then a saturated steam valve is opened, the crystals are purged by using saturated steam, whether mother liquor flows out of a mother liquor pipeline or not is observed, and if no liquid flows out, purging can be stopped; (4) stopping steam blowing and washing, scraping materials by a scraper, entering a cooling process, and cooling the high-temperature crystal which is blown and washed clean by using a vibrating fluidized bed to obtain the crystal. The present invention uses saturated steam to blow the crystal, and the steam temperature is lower than the melting point of the crystal, so no matter how the crystal is blown, the crystal is not lost, and the yield is improved.)

1. A method for washing crystals by saturated steam instead of water in a centrifugal process is characterized by comprising the following steps:

(1) pumping sugar alcohol solution into a vertical crystallization kettle for evaporation, discharging the material after the evaporation is carried out until the refraction, and then feeding the material into a horizontal crystallization tank for cooling crystallization;

(2) cooling and crystallizing to obtain a mixed solution of crystals and mother liquor before centrifugation, and keeping the temperature of the mixed solution in a horizontal crystallizing tank;

(3) the mixed solution is moved to a centrifugal machine for centrifugation, then a saturated steam valve is opened, the saturated steam is used for purging the crystals for 10-20 minutes, whether the mother liquor flows out of the mother liquor pipeline or not is observed, and if no liquid flows out, the purging can be stopped;

(4) stopping steam blowing and washing, enabling scraper scrapes to enter a cooling process, and cooling the blown and washed high-temperature crystal by using a vibrating fluidized bed to obtain the crystal with the water content of 0-0.3% and the temperature of less than or equal to 30 ℃.

2. The method for washing the crystal by using saturated steam instead of water in the centrifugal procedure according to claim 1, which is characterized in that: the centrifugation in the step (3) is divided into three steps: starting at a low speed of 5HZ, distributing at a medium speed of 35HZ, and throwing and centrifuging at a high speed of 50 HZ.

3. The method for washing the crystal by using saturated steam instead of water in the centrifugal procedure according to claim 2, which is characterized in that: the centrifugation is specifically as follows: after 5HZ low-speed operation is started and stable, the centrifugal machine is adjusted to the middle speed of 35HZ, after the rotating speed is stable, the material distribution motor is started, after the rotating speed of the material distribution turntable is stable, the material distribution valve is opened to start material distribution, the material distribution is stopped when the position of the rotary drum 4/5 is reached, the material distribution valve is closed, the compressed air valve is closed, the washing water valve is opened to clean the material distribution pipeline, and the valve is closed after the washing water valve is washed clean; then, removing the liquid at a high speed of 50Hz for 10-20 minutes.

4. The method for washing the crystal by using saturated steam instead of water in the centrifugal procedure according to claim 1, which is characterized in that: the temperature of the cooling air of the vibrated fluidized bed in the step (4) is less than or equal to 18 ℃.

5. The method for washing the crystal by using saturated steam instead of water in the centrifugal procedure according to claim 1, which is characterized in that: and (4) blowing the crystals by saturated steam in the step (3), wherein the temperature of the saturated steam is lower than the melting point temperature of the crystals by more than 5 ℃.

Technical Field

The invention relates to the technical field of sugar alcohol preparation, and particularly relates to a method for replacing water washing crystals with saturated steam in a centrifugal process.

Background

The melting point is substantially the temperature at which the two phases of solid and liquid of the substance can coexist and be in equilibrium, and taking the case of melting ice into water, the melting point of ice is 0 ℃ at one atmosphere, and at a temperature of 0 ℃, ice and water can coexist, and the coexisting state of ice and water can be kept stable for a long period of time if there is no heat exchange with the outside. The melting point and the freezing point of the crystalline material are the same at a given pressure. When the temperature of the crystal exceeds the melting temperature, the crystal slowly melts into a liquid state, i.e., a molten state, and if the temperature is not higher than the melting point of the crystal, the crystal does not assume a molten state, but a solid state, regardless of how the crystal is heated.

When using water to wash the crystal layer among the prior art, the initial time water has washed away the mother liquor that is the crystal surface, can be that the crystal layer is thicker, and water still will continue to wash, and such result is that pivoted crystal inboard has been washed, but the outer end crystal still has not been washed, consequently need continue to add water and wash, just so led to the crystal part of the first contact washing water to dissolve, the crystal of outside can just be washed clean, consequently caused certain crystal loss, reduced the yield.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to provide a method for replacing water washing crystals with saturated steam in a centrifugal process aiming at the defects in the prior art.

The technical scheme is as follows: the invention relates to a method for replacing water washing crystals with saturated steam in a centrifugal process, which comprises the following steps:

(1) pumping sugar alcohol solution into a vertical crystallization kettle for evaporation, discharging the material after the evaporation is carried out until the refraction, and then feeding the material into a horizontal crystallization tank for cooling crystallization;

(2) cooling and crystallizing to obtain a mixed solution of crystals and mother liquor before centrifugation, and keeping the temperature of the mixed solution in a horizontal crystallizing tank;

(3) the mixed solution is moved to a centrifugal machine for centrifugation, then a saturated steam valve is opened, the saturated steam is used for purging the crystals for 10-20 minutes, whether the mother liquor flows out of the mother liquor pipeline or not is observed, and if no liquid flows out, the purging can be stopped;

(4) stopping steam blowing and washing, enabling scraper scrapes to enter a cooling process, and cooling the blown and washed high-temperature crystal by using a vibrating fluidized bed to obtain the crystal with the water content of 0-0.3% and the temperature of less than or equal to 30 ℃.

Further, the centrifugation in the step (3) is divided into three steps: starting at a low speed of 5HZ, distributing at a medium speed of 35HZ, and throwing and centrifuging at a high speed of 50 HZ.

Further, the centrifugation is specifically as follows: after 5HZ low-speed operation is started and stable, the centrifugal machine is adjusted to the middle speed of 35HZ, after the rotating speed is stable, the material distribution motor is started, after the rotating speed of the material distribution turntable is stable, the material distribution valve is opened to start material distribution, the material distribution is stopped when the position of the rotary drum 4/5 is reached, the material distribution valve is closed, the compressed air valve is closed, the washing water valve is opened to clean the material distribution pipeline, and the valve is closed after the washing water valve is washed clean; then, removing the liquid at a high speed of 50Hz for 10-20 minutes.

Further, the temperature of the cooling air of the vibrated fluidized bed in the step (4) is less than or equal to 18 ℃.

Further, in the step (3), saturated steam is used for purging the crystals, and the temperature of the saturated steam is lower than the melting point temperature of the crystals by more than 5 ℃.

The invention has the beneficial effects that:

(1) saturated steam is used for purging the crystals, and the steam temperature is lower than the melting point of the crystals, so no matter how the crystals are purged, the crystals are not lost, and the yield is improved;

(2) after the purging is finished, the mother solution is purged completely, and a steam drying effect is also performed, so that the steam utilization rate is improved, the energy consumption is reduced, and the production cost is reduced;

(3) the crystal content is kept above 99 percent and is far higher than the national standard material, and then the crystal only needs to be cooled and then packaged.

Detailed Description

The invention is further described below with reference to examples:

example 1

Taking maltitol as an example (crystalline maltitol having a melting point of Tr135 ℃ C.)

(1) Pumping a maltitol solution into a vertical crystallization kettle for evaporation, discharging the material after the maltitol solution is evaporated to refract light, and feeding the material into a horizontal crystallization tank for cooling and crystallization;

(2) cooling and crystallizing to obtain a mixed solution of crystals and mother liquor before centrifugation, and keeping the temperature of the mixed solution in a horizontal crystallizing tank;

(3) the mixed solution is moved to a centrifuge for centrifugation, and the centrifugation is divided into three steps: 5HZ low-speed start, 35HZ intermediate speed cloth, 50HZ high-speed material throwing centrifugation specifically are: after 5HZ low-speed operation is started and stable, the centrifugal machine is adjusted to the medium speed of 35HZ, after the rotating speed is stable, the material distribution motor is started, after the rotating speed of the material distribution turntable is stable, the material distribution is started by opening the material discharge valve, the material distribution is stopped when the material reaches the position of the rotary drum 4/5, the material discharge valve is closed, the compressed air valve is closed, the washing water valve is opened to clean the material discharge pipeline, and the valve is closed after the washing water valve is washed clean; then removing liquid at a high speed of 50Hz for 10 minutes;

then, a saturated steam valve is opened, the temperature Tb of the saturated steam is 129 ℃, the saturated steam is used for purging the crystals for 15 minutes, no liquid flows out of a mother liquid pipeline, and purging is stopped;

(4) stopping steam purging, adjusting the rotating speed of the centrifuge, reducing the rotating speed to 5Hz, opening a discharging switch after the low speed is stable, pushing a scraper of a scraper oil tank to act under the action of hydraulic oil, scraping materials on a rotary drum by the scraper, entering a discharging hopper, cooling the centrifugally purged high-temperature crystals by using a vibrating fluidized bed, and obtaining the maltitol crystals at the cooling wind temperature of 18 ℃ by using the vibrating fluidized bed, wherein the total yield is 73%, and the usage amount of the maltitol crystal steam per unit with the content of 99.0-99.9% at the temperature of 28 ℃ is 2.4 tons per ton of crystals.

Comparative example 1 aqueous maltitol rinse

Pumping a maltitol solution into a vertical crystallization kettle for evaporation, discharging the material after the maltitol solution is evaporated to refract light, and feeding the material into a horizontal crystallization tank for cooling and crystallization; cooling and crystallizing to obtain a mixed solution of crystals and mother liquor before centrifugation, adjusting the speed of the centrifuge to 35Hz, opening a steam valve after the rotating speed is stable, heating the centrifuge to about 40 ℃, and closing the steam valve;

opening a material distribution motor, opening a material discharge valve to start material distribution after the rotating speed of a material distribution turntable is stable, stopping material distribution when the position of a rotating drum 4/5 is reached, closing the material discharge valve, closing a compressed air valve, opening a washing water valve to clean a material discharge pipeline, closing the valve after the material discharge pipeline is washed clean, performing liquid removal at a high speed of 50Hz, opening a water spraying washing switch to wash the material for 20 minutes after 10 minutes of liquid removal is finished, and then performing spin-drying on the material by using a centrifugal machine for 32 minutes;

regulating the rotating speed, reducing the rotating speed to 5Hz at a low speed, opening a discharging switch after the low speed is stable, pushing a scraper to act by a scraper oil tank under the action of hydraulic oil, scraping materials on a rotary drum by the scraper, entering a discharging hopper, cooling the centrifugally blasted crystal by using a vibrating fluidized bed, and obtaining the maltitol crystals with the total yield of 65 percent and the unit maltitol crystal water usage amount of 3.5 tons/ton crystals and the content of 98.5-99.5 percent by using the vibrating fluidized bed at the cooling wind temperature of 18 DEG C

Thus, it can be seen that: firstly, the method does not need to carry out centrifugal operation after saturated steam is used for purging crystals, so that the centrifugal time is shortened; moreover, the water content of the obtained maltitol crystals is extremely low, and the cost is lower compared with the cost consumed by water leaching.

Example 2

Taking erythritol as an example (crystalline erythritol having a melting point: Tr126 ℃ C.)

(1) Pumping erythritol solution into a vertical crystallization kettle for evaporation, discharging materials after evaporation until refraction, entering a horizontal crystallization tank, and cooling and crystallizing;

(2) cooling and crystallizing to obtain a mixed solution of crystals and mother liquor before centrifugation, and keeping the temperature of the mixed solution in a horizontal crystallizing tank;

(3) the mixed solution is moved to a centrifuge for centrifugation, and the centrifugation is divided into three steps: 5HZ low-speed start, 35HZ intermediate speed cloth, 50HZ high-speed material throwing centrifugation specifically are: after 5HZ low-speed operation is started and stable, the centrifugal machine is adjusted to the medium speed of 35HZ, after the rotating speed is stable, the material distribution motor is started, after the rotating speed of the material distribution turntable is stable, the material distribution is started by opening the material discharge valve, the material distribution is stopped when the material reaches the position of the rotary drum 4/5, the material discharge valve is closed, the compressed air valve is closed, the washing water valve is opened to clean the material discharge pipeline, and the valve is closed after the washing water valve is washed clean; then removing liquid at a high speed of 50Hz for 12 minutes;

then, a saturated steam valve is opened, the temperature Tb of the saturated steam is 118 ℃, the saturated steam is used for purging the crystals for 18 minutes, no liquid flows out of a mother liquid pipeline, and purging is stopped;

(4) stopping steam purging, adjusting the rotating speed of the centrifuge, reducing the rotating speed to 5Hz, opening a discharging switch after the low speed is stable, pushing a scraper of a scraper oil tank to act under the action of hydraulic oil, scraping materials on a rotary drum by the scraper, entering a discharging hopper, cooling the centrifugally purged high-temperature crystal by using a vibrating fluidized bed, and obtaining the erythritol crystal at the cooling wind temperature of 18 ℃ by using the vibrating fluidized bed, wherein the total yield is 61.8%, and the usage amount of the erythritol crystal steam at 25 ℃ and the content of 99.0-99.9% per unit is 2.7 tons per ton of crystal.

Comparative example 2 aqueous erythritol elution

Pumping erythritol solution into a vertical crystallization kettle for evaporation, discharging materials after evaporation until refraction, entering a horizontal crystallization tank, and cooling and crystallizing; cooling and crystallizing to obtain a mixed solution of crystals and mother liquor before centrifugation, adjusting the speed of the centrifuge to 35Hz, opening a steam valve after the rotating speed is stable, heating the centrifuge to about 40 ℃, and closing the steam valve;

opening a material distribution motor, opening a material discharge valve to start material distribution after the rotating speed of a material distribution turntable is stable, stopping material distribution when the position of a rotating drum 4/5 is reached, closing the material discharge valve, closing a compressed air valve, opening a washing water valve to clean a material discharge pipeline, closing the valve after the material discharge pipeline is washed clean, performing liquid removal at a high speed of 50Hz, opening a water spraying washing switch to wash the material for 26 minutes after 10 minutes of liquid removal is finished, and then performing spin-drying on the material by using a centrifugal machine for 38 minutes;

adjusting the rotating speed, reducing the rotating speed to 5Hz at a low speed, opening a discharging switch after the low speed is stable, pushing a scraper to act under the action of hydraulic oil by a scraper oil tank, scraping materials on a rotary drum by the scraper, entering a discharging hopper, cooling the centrifugally blasted crystal by using a vibrating fluidized bed, and obtaining the erythritol crystal with the total yield of 53.5 percent and the unit erythritol crystal water usage amount of 4.5 tons/ton crystals with the content of 99-99.5 percent at the cooling wind temperature of 18 ℃ by using the vibrating fluidized bed

Thus, it can be seen that: firstly, the method does not need to carry out centrifugal operation after saturated steam is used for purging crystals, so that the centrifugal time is shortened; and the water content of the obtained erythritol crystals is extremely low, so that the cost is lower compared with the cost consumed by water leaching.

Example 3

Taking xylitol as an example (melting point of crystalline xylitol: Tr150-152 ℃)

(1) Pumping xylitol solution into a vertical crystallization kettle for evaporation, discharging the material after evaporation until refraction, and entering a horizontal crystallization tank for cooling crystallization;

(2) cooling and crystallizing to obtain a mixed solution of crystals and mother liquor before centrifugation, and keeping the temperature of the mixed solution in a horizontal crystallizing tank;

(3) the mixed solution is moved to a centrifuge for centrifugation, and the centrifugation is divided into three steps: 5HZ low-speed start, 35HZ intermediate speed cloth, 50HZ high-speed material throwing centrifugation specifically are: after 5HZ low-speed operation is started and stable, the centrifugal machine is adjusted to the medium speed of 35HZ, after the rotating speed is stable, the material distribution motor is started, after the rotating speed of the material distribution turntable is stable, the material distribution is started by opening the material discharge valve, the material distribution is stopped when the material reaches the position of the rotary drum 4/5, the material discharge valve is closed, the compressed air valve is closed, the washing water valve is opened to clean the material discharge pipeline, and the valve is closed after the washing water valve is washed clean; then removing liquid at a high speed of 50Hz for 20 minutes;

then, a saturated steam valve is opened, the temperature Tb of the saturated steam is 145 ℃, the saturated steam is used for purging the crystals for 18 minutes, no liquid flows out of a mother liquid pipeline, and purging is stopped;

(4) stopping steam blowing, adjusting the rotating speed of the centrifugal machine, reducing the rotating speed to 5Hz, opening a discharging switch after the low speed is stable, pushing a scraper of a scraper oil tank to act under the action of hydraulic oil, scraping materials on a rotary drum by the scraper, entering a discharging hopper, cooling the centrifugally blown and cleaned high-temperature crystals by using a vibrating fluidized bed, wherein the temperature of cooling air of the vibrating fluidized bed is 18 ℃, obtaining xylitol crystals, the total yield is 88.9%, and the content of xylitol crystals at 27 ℃ is 99.0-99.9%, and the using amount of unit xylitol crystal steam is 3.1 ton/ton crystals.

Comparative example 2 aqueous xylitol drip washing

Pumping xylitol solution into a vertical crystallization kettle for evaporation, discharging the material after evaporation until refraction, and entering a horizontal crystallization tank for cooling crystallization; cooling and crystallizing to obtain a mixed solution of crystals and mother liquor before centrifugation, adjusting the speed of the centrifuge to 35Hz, opening a steam valve after the rotating speed is stable, heating the centrifuge to about 40 ℃, and closing the steam valve;

opening a material distribution motor, opening a material discharge valve to start material distribution after the rotating speed of a material distribution turntable is stable, stopping material distribution when the position of a rotating drum 4/5 is reached, closing the material discharge valve, closing a compressed air valve, opening a washing water valve to clean a material discharge pipeline, closing the valve after the material discharge pipeline is washed clean, performing liquid removal at a high speed of 50Hz, opening a water spraying washing switch to wash the material for 32 minutes after the liquid removal is completed for 10 minutes, and then performing spin-drying on the material by using a centrifugal machine for 26 minutes;

regulating the rotating speed, reducing the rotating speed to 5Hz at a low speed, opening a discharging switch after the low speed is stable, pushing a scraper to act by a scraper oil tank under the action of hydraulic oil, scraping materials on a rotary drum by the scraper, entering a discharging hopper, cooling the centrifugally blasted crystal by using a vibrating fluidized bed, and obtaining the xylitol crystal with the total yield of 83 percent and the unit xylitol crystal water usage of 98.5-99.2 percent per ton of crystal at the temperature of 18 ℃ by using the cooling air of the vibrating fluidized bed

Thus, it can be seen that: firstly, the method does not need to carry out centrifugal operation after saturated steam is used for purging crystals, so that the centrifugal time is shortened; and the obtained xylitol crystal has extremely low water content and lower cost compared with water leaching consumption.