Device and method for extracting sucralose powder from sucralose mother liquor

Abstract

The present invention relates to the technical field of sucralose production, and discloses a device and method for extracting sucralose powdered sugar from sucralose mother liquor, comprising a sucralose mother liquor storage tank, a delivery pump group, a swirl propulsion drying pipe, a diaphragm compressor, a high-temperature compressed air storage tank, a separator, and a buffer air bag. The swirl propulsion drying pipe inlet end cap is provided with a spray gun, the inlet and outlet of the delivery pump group are respectively connected to the sucralose mother liquor storage tank outlet and the spray gun inlet, the swirl propulsion drying pipe outlet is connected to the separator, the separator gas phase outlet is connected to the buffer air bag inlet, the diaphragm compressor inlet is connected to the air pipeline, and the outlet is connected to the high-temperature compressed air storage tank inlet. The present invention sprays the sucralose mother liquor first by swirl propulsion drying to obtain solid sugar powder removed from tetramethyl urea and a hot air flow. The swirl propulsion drying pipe is simple to manufacture and occupies a small area. The air flow rotates and advances at high speed in the pipe, and the drying material simultaneously sweeps the pipe wall, thereby avoiding the phenomenon of sugar powder sticking to the wall.

Description

Technical Field

[0001] The present invention relates to a sucralose production technology, and in particular to a device and method for extracting sucralose powder from sucralose mother liquor. Background Art

[0002] Sucralose (CAS No. 56038-13-2), commonly known as sucralose, is a high-intensity sweetener with a molecular formula of C12H19Cl3O8. It is highly stable, stable to light, heat, and pH, highly soluble in water, low in calories, highly safe, and virtually non-absorbable by the human body. It is one of the most ideal sweeteners with a promising market. The current industrial synthesis method for sucralose is to use sucrose as the raw material, esterify sucrose to produce sucrose-6-ethyl ester, then chlorinate the sucrose-6-ethyl ester to produce sucralose-6-ethyl ester, and finally de-esterify the sucralose-6-ethyl ester to obtain sucralose.

[0003] During the sucralose production process, the mother liquor from multiple crystallizations (liquid chromatography analysis shows sucralose content of 85% to 95%) is often plagued by complex impurities and difficult to crystallize. This results in a dark brown color, high viscosity, and high yield. Extracting the sucralose product from this mother liquor poses a major challenge for manufacturers, aiming to improve yield and minimize contamination.

[0004] Patent application number 201910029069.X discloses a method for extracting sucralose from multiple mother liquors, and patent application number 202111393590.5 discloses a method for treating sucralose crystallization mother liquors. Both methods use an oxidant to treat the sucralose mother liquors, reacting at a relatively low temperature for a relatively long time. Alkali is then used to destroy excess oxidant, and the pH is then adjusted to neutral. These methods involve complex procedures and require extensive equipment.

[0005] Experiments have shown that sucralose mother liquor contains a component that hinders crystallization: tetramethylurea, with a content of approximately 4% to 9%. When the content of this substance is reduced to <0.5%, the crystallization speed will be accelerated and the crystallization rate will also increase.

[0006] Tetramethylurea is a byproduct of the sucralose production process, generated by the decomposition and recombination of dimethylformamide (DMF). At standard atmospheric pressure, tetramethylurea has a boiling point of 175°C.

[0007] Oxidants such as hydrogen peroxide can slowly decompose tetramethyl urea, thereby achieving the purpose of reducing the content of tetramethyl urea by chemical methods.

[0008] Physical distillation can also reduce tetramethylurea content, but the effect is minimal. During the evaporation and concentration process, the sucralose mother liquor becomes increasingly viscous, eventually becoming a paste. Tetramethylurea has a high boiling point (175°C), and when mixed with the mother liquor, it requires continuous addition of water or solvents such as ethyl acetate, followed by dilution and reconcentration, and this cycle is repeated to achieve the desired reduction in tetramethylurea content. Overall, physical distillation is slow to achieve results in removing tetramethylurea and is unsuitable for scale-up production.

[0009] By using the physical method of spray drying the mother liquor, the mother liquor is turned into extremely tiny mist droplets, the surface area is increased, and it is instantly exposed to the hot air flow, the solvent evaporates, and solid sugar powder is obtained. The solvent turns into gas and is discharged with the hot air flow, thereby achieving the purpose of solid-liquid separation.

[0010] Conventional spray drying process Figure 4 As shown in the figure, the spray drying method was applied to the process of removing tetramethylurea from sucralose mother liquor, and four problems were found:

[0011] 1) Traditional spray drying equipment is prone to wall sticking. The sticky material is difficult to clean and easily absorbs high-boiling-point tetramethylurea. Even if it is cleaned, the purpose of removing tetramethylurea is not achieved.

[0012] 2) Traditional spray equipment is relatively large and occupies a large area of ​​factory buildings;

[0013] 3) Tetramethylurea has a high boiling point and is not easy to vaporize. Spray drying equipment is large in size and requires a large amount of hot air. If the temperature is not properly controlled, tetramethylurea will be wrapped in the solid sugar powder, seriously affecting the subsequent crystallization and purification work.

[0014] 4) The exhaust gas from traditional spray drying equipment has a high temperature and contains some organic compounds. Direct discharge into the atmosphere will cause environmental pollution and requires cooling, absorption, and purification treatment, which is a complicated process. Not only is the heat of the exhaust gas itself wasted, but additional energy is also required to cool it down.

[0015] Patent application number 201520260188.3 discloses a fluidized drying system that uses a cyclone drying tube, a cyclone separator, and a fluidized bed to dry PVB resin. The problems with the airflow drying tube are:

[0016] 1) The cyclone drying tube is designed to process solid PVB particles, but cannot dry liquid spray;

[0017] 2) The energy utilization rate is low and it is easy to pollute the atmosphere. The exhaust gas discharged after drying contains a large amount of heat and organic matter, and direct discharge will pollute the atmosphere.

[0018] In view of the above problems, we have developed a method for extracting sucralose powdered sugar from sucralose mother liquor. Cyclone propulsion drying is used to remove tetramethylurea in the mother liquor to obtain solid sugar powder that is easy to crystallize. The sugar powder is then dissolved, crystallized, and filtered to obtain a product with a higher content of sucralose. The hot gas discharged after drying contains a certain amount of organic solvent components, which are uniformly collected and entered into a buffer gas bag. It is then transported by a blower to a sucralose waste liquid incinerator. While the gas meets the emission standards, the heat is fully utilized. Summary of the Invention

[0019] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a device and method for extracting sucralose powder from sucralose mother liquor.

[0020] To achieve the above-mentioned object, the technical solution of the present invention is: a device for extracting sucralose powder from sucralose mother liquor, comprising a sucralose mother liquor storage tank, a delivery pump group, a swirl propulsion drying tube, a diaphragm compressor, a high-temperature compressed air storage tank, a separator, and a buffer air bag. The inlet end cover of the swirl propulsion drying tube is equipped with a spray gun. The inlet and outlet of the delivery pump group are connected to the outlet of the sucralose mother liquor storage tank and the inlet of the spray gun respectively through pipelines. The outlet of the swirl propulsion drying tube is connected to the inlet of the separator along a tangential direction. The top of the separator is a gas phase outlet. The gas phase outlet of the separator is connected to the inlet of the buffer air bag through a pipeline. The outlet of the buffer air bag is connected to a sucralose waste liquid incinerator through a pipeline. The inlet of the diaphragm compressor is connected to an air pipeline, and the outlet is connected to the inlet of the high-temperature compressed air storage tank through a pipeline. The inlet end cover of the swirl propulsion drying tube is uniformly distributed with three air inlet pipes around the spray gun tip. The outlet pipeline of the high-temperature compressed air storage tank is divided into three branches, which are respectively connected to the inlets of the three air inlets.

[0021] Furthermore, the spray gun head is located at the center of the inlet end cover of the swirl propulsion drying tube, the three air inlet pipe outlets are facing the tube wall of the swirl propulsion drying tube, and the line between the center of the inlet end cover of the swirl propulsion drying tube and the air inlet pipe inlet is the center line. The angle between the air inlet pipe outlet and the center line is α, 30°≤α≤60°.

[0022] Furthermore, a blower is provided on the outlet pipeline of the buffer air bag.

[0023] Furthermore, the spray gun inlet is also connected to a normal temperature compressed air pipeline.

[0024] Furthermore, a screen is provided at the upper end of the separator near the gas phase outlet, a V-shaped powdered sugar outlet is provided at the lower end of the separator, and a powdered sugar feed cart is provided at the lower end of the powdered sugar outlet.

[0025] Furthermore, the delivery pump group is composed of two centrifugal pumps connected in parallel.

[0026] Furthermore, a first thermometer and a first flow meter are provided on the inlet air pipeline of the diaphragm compressor, a second thermometer and a first pressure gauge are provided on the high-temperature compressed air storage tank, a second flow meter is provided on the outlet pipeline of the delivery pump group, a third thermometer and a second pressure gauge are provided on the upper end of the separator, and a fourth thermometer is provided at the powdered sugar outlet.

[0027] Another technical solution of the present invention is: a method for extracting sucralose powder from sucralose mother liquor, comprising the following steps:

[0028] 1) Compression: The diaphragm compressor compresses the air adiabatically. The compressed air enters the high-temperature compressed air storage tank. The first thermometer displays the atmospheric temperature. The flow rate of the first flowmeter is adjusted to 1875-3000 kg / h. The pressure displayed by the first pressure gauge is 6-8 bar. The temperature displayed by the second thermometer is 285-340°C.

[0029] 2) Cyclone propulsion drying: Compressed air in the high-temperature compressed air storage tank is ejected toward the wall of the cyclone propulsion drying tube through three air inlet pipes on the inlet end cap of the cyclone propulsion drying tube, forming a high-temperature, high-speed rotating airflow. The sucralose mother liquor is delivered to the spray gun via a delivery pump assembly. The flow rate of the second flow meter is adjusted to 100 kg / h. Simultaneously, room-temperature compressed air is supplied to the spray gun. The spray gun sprays the sucralose mother liquor into the cyclone propulsion drying tube in the form of a mist. The misted sucralose mother liquor is pushed toward the outlet of the cyclone propulsion drying tube by the high-temperature, high-speed rotating airflow. During this process, the sucralose mother liquor changes from a mist to solid sugar powder, and the solvent changes to a gas. The solvent includes tetramethyl urea.

[0030] 3) Gas-solid separation: Solid powdered sugar and air flow enter the separator along a tangential direction. The powdered sugar descends and enters the powdered sugar feed car through a V-shaped powdered sugar outlet. The air flow rises, passes through a screen, enters a buffer air bag, and is then transported by a blower to a sucralose waste liquid incinerator for harmless treatment. The third thermometer in the separator shows a temperature of 185-215°C, the second pressure gauge shows a pressure of 10-50 kPa, and the fourth thermometer shows a temperature of 80-150°C.

[0031] 4) Dissolution and crystallization: The powdered sugar collected from the powdered sugar truck was heated and dissolved in ethyl acetate, then cooled to crystallize, and filtered to obtain sucralose solid.

[0032] From a macroscopic perspective, the work done by the diaphragm compressor increases the air pressure and temperature. Part of the heat is used to dry the mother liquor, while the rest enters the incinerator to generate steam. The energy utilization rate is higher than that of traditional spray drying equipment.

[0033] The swirl-driven drying tube is considered as a heat exchange module (MIX). The four input streams are: mother liquor stream A (replaced by water because water has a higher specific heat and the results are more reliable), tetramethylurea stream B, oxygen stream C, and nitrogen stream D; the output stream is E. (The room temperature compressed air used by the spray gun is negligible due to its small amount). Figure 5 As shown, the temperature data of each stream was calculated using thermodynamic software, and the results are shown in Tables 1 and 2.

[0034] Table 1 Temperature distribution of each stream in the swirl propulsion drying tube when the high-temperature compressed air temperature is 285℃

[0035]

[0036] Table 2 Temperature distribution of each stream in the swirl propulsion drying tube when the high-temperature compressed air temperature is 340℃

[0037]

[0038] According to the data in Tables 1 and 2, when the air flow rate (C+D) is between 1875-3000 kg / h and the temperature is between 285-340°C, the air flow temperature at the outlet of the swirl propulsion drying tube is about 194°C, which is greater than the boiling point of tetramethylurea, 175°C. At this time, tetramethylurea is in gaseous state.

[0039] Beneficial effects of the present invention:

[0040] 1) The present invention is rationally designed and simple to implement. The sucralose mother liquor is sprayed and first subjected to swirl propulsion drying to produce solid sugar powder from which tetramethylurea has been removed, along with a hot air flow. The swirl propulsion drying tube is simple to manufacture and occupies a small footprint. The airflow rotates at high speed within the tube, simultaneously sweeping the tube wall while drying the material, thus preventing the sugar powder from adhering to the wall.

[0041] 2) The present invention can ensure that tetramethylurea always exists in a gaseous state in the separator by controlling the flow rate, temperature, and pressure parameters, thereby preventing the high-boiling-point tetramethylurea from becoming liquid and being wrapped in the solid powdered sugar;

[0042] 3) The present invention collects the hot air flow and organic solvent gas finally discharged into a buffer gas bag and transports them to the sucralose waste liquid incinerator by a blower to produce steam. While the gas meets the emission standards, the heat is fully utilized. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic diagram of the structure of the device of the present invention;

[0044] Figure 2 This is a cross-sectional view of the inlet end cover of the swirl propulsion drying tube of the present invention;

[0045] Figure 3 It is a cross-sectional view of the separator inlet of the present invention;

[0046] Figure 4 This is a schematic diagram of the traditional spray drying process;

[0047] Figure 5 This is a flow chart when the swirl propulsion drying tube is regarded as a MIX.

[0048] In the figure: 1. Diaphragm compressor; 2. High-temperature compressed air storage tank; 3. Sucralose mother liquor storage tank; 4. Delivery pump group; 5. Spray gun; 6. Cyclone propulsion drying tube; 7. Separator; 8. Buffer air bag; 9. Blower; 10. Air inlet pipe; 11. Screen; 12. Powdered sugar outlet; 13. Powdered sugar material cart; T1, first thermometer; T2, second thermometer; T3, third thermometer; T4, fourth thermometer; F1, first flowmeter; F2, second flowmeter; P1, first pressure gauge; P2, second pressure gauge. DETAILED DESCRIPTION

[0049] Example 1:

[0050] like Figures 1 to 3 As shown, a device for extracting sucralose powder from sucralose mother liquor includes a sucralose mother liquor storage tank 3, a delivery pump group 4, a swirl propulsion drying tube 6, a diaphragm compressor 1, a high-temperature compressed air storage tank 2, a separator 7, and a buffer air bag 8. A spray gun 5 is installed at the center of the inlet end cover of the swirl propulsion drying tube 6. The inlet and outlet of the delivery pump group 4 are connected to the outlet of the sucralose mother liquor storage tank 3 and the inlet of the spray gun 5 through pipelines, respectively. The inlet of the spray gun 5 is also connected to a normal temperature compressed air pipeline. The outlet of the swirl propulsion drying tube 6 is connected to the inlet of the separator 7 along a tangential direction. The top of the separator 7 is a gas phase outlet. A screen 11 is provided at the upper end of the separator 7 near the gas phase outlet. A V-shaped powdered sugar outlet 12 is provided at the lower end of the separator 7. A powdered sugar trolley 13 is provided below the powdered sugar outlet 12. The gas phase outlet of the separator 7 is connected to the inlet of a buffer gas bag 8 via a pipeline. The outlet of the buffer gas bag 8 is connected to the sucralose waste liquid incinerator via a pipeline. The inlet of the diaphragm compressor 1 is connected to an air pipeline, and the outlet is connected to the inlet of the high-temperature compressed air storage tank 2 via a pipeline. The inlet end cap of the swirl propulsion drying tube 6 is uniformly distributed with three air inlet pipes 10 around the gun head 5. The outlet pipe of the high-temperature compressed air storage tank 2 is divided into three branches, each connected to the inlet of the three air inlet pipes 10. The outlets of the three air inlet pipes 10 face the wall of the swirl propulsion drying tube 6. The line connecting the center of the inlet end cap of the swirl propulsion drying tube 6 and the inlet of the air inlet pipe 10 is the center line. The angle between the outlet of the air inlet pipe 10 and the center line is α, and 30°≤α≤60°.

[0051] A blower 9 is provided on the outlet pipeline of the buffer gas bag 8 .

[0052] The delivery pump group 4 is composed of two centrifugal pumps connected in parallel.

[0053] A first thermometer T1 and a first flowmeter F1 are provided on the inlet air pipeline of the diaphragm compressor 1, a second thermometer T2 and a first pressure gauge P1 are provided on the high-temperature compressed air storage tank 2, a second flowmeter F2 is provided on the outlet pipeline of the delivery pump group 4, a third thermometer T3 and a second pressure gauge P2 are provided on the upper end of the separator 7, and a fourth thermometer T4 is provided at the powdered sugar outlet 12.

[0054] A method for extracting sucralose powdered sugar from sucralose mother liquor comprises the following steps:

[0055] 1) Compression: The diaphragm compressor 1 compresses the air adiabatically, and the compressed air enters the high-temperature compressed air storage tank 2. The first thermometer T1 displays the atmospheric temperature. The flow rate of the first flowmeter F1 is adjusted to 1903 kg / h. The pressure displayed by the first pressure gauge P1 is 7.8 bar. The temperature displayed by the second thermometer T2 is 335°C.

[0056] 2) Cyclone propulsion drying: Compressed air in the high-temperature compressed air storage tank 2 is ejected toward the wall of the cyclone propulsion drying tube 6 through three air inlet pipes 10 on the inlet end cap of the cyclone propulsion drying tube 6, forming a high-temperature, high-speed rotating airflow. The sucralose mother liquor is delivered to the spray gun 5 via the delivery pump assembly 4. The flow rate of the second flowmeter F2 is adjusted to 100 kg / h. Simultaneously, room-temperature compressed air at a pressure of 4 bar is supplied to the spray gun 5. The spray gun 5 sprays the sucralose mother liquor into the cyclone propulsion drying tube 6 in the form of a mist. The misted sucralose mother liquor is pushed toward the outlet of the cyclone propulsion drying tube 6 by the high-temperature, high-speed rotating airflow. During this process, the sucralose mother liquor changes from a mist to solid sugar powder, and the solvent, which includes tetramethyl urea, changes to a gas.

[0057] 3) Gas-Solid Separation: Solid powdered sugar and air flow enter separator 7 along a tangential direction. The powdered sugar descends and enters powdered sugar trolley 13 through V-shaped powdered sugar outlet 12. Analysis shows a tetramethylurea content of 0.21% in the powdered sugar. The air flow rises, passes through screen 11, and enters buffer air bag 8. It is then transported by blower 9 to a sucralose waste liquid incinerator for harmless treatment. In separator 7, the third thermometer T3 indicates a temperature of 213° C., the second pressure gauge P2 indicates a pressure of 20 kPa, and the fourth thermometer T4 indicates a temperature of 95° C.

[0058] 4) Dissolution and Crystallization: 100 g of powdered sugar collected from the powdered sugar cart 13 was dissolved in 200 g of ethyl acetate at 70° C., then cooled to allow crystallization. The sucralose solid was filtered and weighed after drying, with a sucralose crystal content of 99.2% by weight.

[0059] Examples 2 to 4:

[0060] The apparatus for extracting sucralose powder from sucralose mother liquor is the same as that in Example 1. The method for extracting sucralose powder from sucralose mother liquor differs from Example 1 in terms of the parameter values ​​in Table 3.

[0061] Table 3 Parameter values ​​in Examples 1 to 4

[0062]

[0063] The above-described embodiments are only preferred solutions of the present invention and are not intended to limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

[0064] In the description of the present invention, it should be understood that the terms indicating orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings and are only used to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, they cannot be understood as limiting the present invention.

Claims

1. A method for extracting sucralose powder from sucralose mother liquor, characterized by: The device used in the method includes a sucralose mother liquor storage tank, a delivery pump group, a swirl propulsion drying tube, a diaphragm compressor, a high-temperature compressed air storage tank, a separator, and a buffer air bag. The inlet end cap of the swirl propulsion drying tube is equipped with a spray gun. The inlet and outlet of the delivery pump group are respectively connected to the outlet of the sucralose mother liquor storage tank and the inlet of the spray gun through pipelines. The outlet of the swirl propulsion drying tube is connected to the inlet of the separator along a tangential direction. The top of the separator is a gas phase outlet. The gas phase outlet of the separator is connected to the inlet of the buffer air bag through a pipeline. The outlet of the buffer air bag is connected to a sucralose waste liquid incinerator through a pipeline. The inlet of the diaphragm compressor is connected to an air pipeline, and the outlet is connected to the inlet of the high-temperature compressed air storage tank through a pipeline. The inlet end cap of the swirl propulsion drying tube is uniformly distributed with three air inlet pipes around the spray gun tip. The outlet pipeline of the high-temperature compressed air storage tank is divided into three branches, which are respectively connected to the inlets of the three air inlets. The method comprises the following steps: 1) Compression gas production: The diaphragm compressor compresses the air adiabatically. The compressed air enters the high-temperature compressed air storage tank. The first thermometer displays the atmospheric temperature. The flow rate of the first flowmeter is adjusted to 1875-3000 kg / h. The pressure displayed by the first pressure gauge is 6-8 bar. The temperature displayed by the second thermometer is 285-340°C. 2) Cyclone propulsion drying: Compressed air in the high-temperature compressed air storage tank is ejected toward the wall of the cyclone propulsion drying tube through three air inlet pipes on the inlet end cap of the cyclone propulsion drying tube, forming a high-temperature, high-speed rotating airflow. The sucralose mother liquor is delivered to the spray gun via a delivery pump assembly. The flow rate of the second flow meter is adjusted to 100 kg / h. Simultaneously, room-temperature compressed air is supplied to the spray gun. The spray gun sprays the sucralose mother liquor into the cyclone propulsion drying tube in the form of a mist. The misted sucralose mother liquor is pushed toward the outlet of the cyclone propulsion drying tube by the high-temperature, high-speed rotating airflow. During this process, the sucralose mother liquor changes from a mist to solid sugar powder, and the solvent, which includes tetramethyl urea, changes to a gas. 3) Gas-Solid Separation: Solid powdered sugar and air flow enter the separator tangentially. The powdered sugar descends and enters the powdered sugar feed truck through a V-shaped powdered sugar outlet. The airflow rises, passes through a screen, and enters a buffer air bag. It is then transported by a blower to the sucralose waste liquid incinerator for harmless treatment. The third thermometer in the separator displays a temperature of 185-215°C, the second pressure gauge displays a pressure of 10-50 kPa, and the fourth thermometer displays a temperature of 80-150°C. 4) Dissolution and crystallization: The powdered sugar collected from the powdered sugar truck is heated and dissolved in ethyl acetate, then cooled to crystallize, and filtered to obtain sucralose solid.

2. The method for extracting sucralose powder from sucralose mother liquor according to claim 1, wherein: The spray gun head is located at the center of the inlet end cover of the swirl propulsion drying tube, and the three air inlet pipe outlets face the tube wall of the swirl propulsion drying tube. The line connecting the center of the inlet end cover of the swirl propulsion drying tube and the inlet of the air inlet pipe is the center line. The angle between the air inlet pipe outlet and the center line is α, 30°≤α≤60°.

3. The method for extracting sucralose powder from sucralose mother liquor according to claim 1, wherein: A blower is provided on the outlet pipeline of the buffer air bag.

4. The method for extracting sucralose powder from sucralose mother liquor according to claim 1, wherein: The spray gun inlet is also connected to a normal temperature compressed air pipeline.

5. The method for extracting sucralose powder from sucralose mother liquor according to claim 1, wherein: A screen is provided at the upper end of the separator near the gas phase outlet, a V-shaped powdered sugar outlet is provided at the lower end of the separator, and a powdered sugar trolley is provided at the lower end of the powdered sugar outlet.

6. The method for extracting sucralose powder from sucralose mother liquor according to claim 1, wherein: The delivery pump group is composed of two centrifugal pumps connected in parallel.

7. The method for extracting sucralose powder from sucralose mother liquor according to claim 5, wherein: A first thermometer and a first flow meter are provided on the inlet air pipeline of the diaphragm compressor, a second thermometer and a first pressure gauge are provided on the high-temperature compressed air storage tank, a second flow meter is provided on the outlet pipeline of the delivery pump group, a third thermometer and a second pressure gauge are provided on the upper end of the separator, and a fourth thermometer is provided at the powdered sugar outlet.

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