Process water distillation system and method of operating a process water distillation system

Abstract

A process water distillation system includes an evaporator, a condenser, and a compressor configured to generate a desired pressure in at least one region of the process water distillation system during operation of the process water distillation system and to transport vapor from the evaporator to the condenser. The condenser is in thermal contact with the evaporator such that, at least during certain operating phases of the process water distillation system, thermal energy released upon condensation of the vapor transported to the condenser is transferred to a fluid in the evaporator. Moreover, the process water distillation system includes a concentrate collection region configured to receive concentrate produced during operation of the process water distillation system and an energy source configured to supply energy to the process water distillation system. A control device is configured to control the supply of energy from the energy source to the process water distillation system in accordance with progress of a distillation process in the process water distillation system.

Description

Technical Field

[0001] This invention relates to a process water distillation system and a method for operating the process water distillation system. Background Technology

[0002] Vacuum distillation represents an effective and economical method for purifying contaminated liquids, such as those used as washing solutions in immersion, spraying, and ultrasonic cleaning systems; as process solutions in surface finishing processes such as electroplating, pickling, anodizing, vibratory grinding, degreasing, phosphating, polishing, powder coating, or painting; or generated in drilling, cutting, grinding, and drawing applications, as well as in die casting. These fluids can be contaminated, for example, with solvents, oils, waxes, hydraulic fluids, and / or coolants.

[0003] DE 10 2005 049 923 B4 discloses a distillation system for purifying industrial wastewater / process water. The distillation system includes a vessel with an evaporator / condenser unit and a vapor compressor that provides the required pressure ratio for evaporation / condensation in the distillation system. The evaporator unit evaporates the contaminated liquid supplied to the vessel, where undesirable components (e.g., silicones, siloxanes, glycols, waxes, oils, amines, emulsifiers, surfactants, salts, etc.) are collected in an evaporator reservoir in the bottom region of the vessel. Meanwhile, purified water vapor rises in the vessel and is extracted by the vapor compressor above a mist separator, and delivered to the evaporator / condenser unit. In the condenser of the evaporator / condenser unit, the water vapor condenses into a purified distillate, which is ultimately supplied to a distillate cooler. The distillate cooler also serves as a preheater for the contaminated liquid to be supplied to the vessel or the evaporator of the evaporator / condenser unit, respectively. Summary of the Invention

[0004] The objective of this invention is to provide a process water distillation system that effectively and efficiently purifies wastewater. Furthermore, this invention aims to provide a method for operating such a process water distillation system.

[0005] A process water distillation system includes an evaporator, a condenser, and a compressor. The compressor is configured to generate a desired pressure in at least one region of the process water distillation system during operation and to deliver steam from the evaporator to the condenser. The condenser is in thermal contact with the evaporator, such that, at least during certain operating phases of the process water distillation system, the heat energy released during the condensation of the steam delivered to the condenser is transferred to the fluid in the evaporator.

[0006] For example, the evaporator can be located in the tube bundle receiving area of ​​the distillation vessel in a process water distillation system. The condenser can be defined, for example, by the internal volume of the tubes of the tube bundle. The condensate in the tubes of the tube bundle is then surrounded by the fluid to be evaporated in the evaporator, so that heat energy can be continuously transferred from the condensate in the condenser to the fluid to be evaporated in the evaporator.

[0007] Furthermore, the process water distillation system includes a concentrate collection area configured to receive concentrates generated during operation of the process water distillation system. The concentrates typically contain low-volatility impurities that do not evaporate during the distillation process occurring within the process water distillation system and are therefore collected in the concentrate collection area. For example, the concentrate collection area may be located in a storage tank within the distillation vessel.

[0008] As the distillation process proceeds, the composition of the concentrate collected in the concentrate collection area typically changes, making the concentrate rich in low-volatile components, such as oily impurities. This resulting increase in the boiling point of the concentrate reduces the temperature difference between the evaporator and the condenser, thus slowing down heat transfer and energy recovery between them. Consequently, the distillation process slows down and eventually stops.

[0009] Therefore, the process water distillation system is additionally equipped with an energy source configured to supply energy to the process water distillation system. Furthermore, a control device is provided, configured to control the energy supply from the energy source to the process water distillation system based on the progress of the distillation process within the system. For example, the progress of the distillation process can be detected by determining whether the distillation process is still running or has stopped and / or by determining the rate of the distillation process; the control device uses this progress as a control parameter to control the energy supply from the energy source.

[0010] In the process water distillation system described herein, the use of additional energy provided by an energy source enables the distillation process to be maintained even when it is in thermodynamic equilibrium without external energy input. As mentioned above, the distillation process increasingly stops due to the increased boiling point of the concentrate and the resulting slowdown in heat transfer between the condenser and evaporator. The input of additional energy alters the thermodynamic equilibrium to allow the distillation process to continue, resulting in an increase in the concentration or thickening of the concentrate. Therefore, the process water distillation system is particularly effective and efficient in purifying wastewater.

[0011] In a preferred embodiment of the process water distillation system, the energy source includes a hot gas source configured to supply hot gas to the process water distillation system. The hot gas supplied by the hot gas source can be used to provide thermal energy to facilitate or sustain the heat transfer process between the condenser and the evaporator, so that the compression, superheating, and condensation of water vapor in the condenser can be optimally and therefore particularly efficiently utilized to compensate for the increase in the boiling point of the concentrate.

[0012] The heat source can be configured to supply heat to the evaporator and / or condenser. The heat can be introduced directly into the evaporator and / or condenser. Alternatively, if it is to prevent the heat from mixing with the steam / water in the evaporator and / or condenser, the heat can only have thermal contact with the evaporator and / or condenser.

[0013] In a particularly preferred embodiment of the process water distillation system, the heat source includes an external steam source, i.e., a steam source formed separately from the evaporator of the process water distillation system, which is configured to supply water vapor to the process water distillation system. The water vapor supplied by the external steam source (e.g., an external steam generator) can be particularly easily integrated into the heat transfer process between the condenser and evaporator because the water vapor does not introduce any substances that are not already present there into the condenser and / or evaporator.

[0014] A heat source can be connected to the evaporator section of the distillation vessel in a process water distillation system. For example, the heat source can be directly connected to the distillation vessel of the process water distillation system via a heat supply line. Alternatively, the heat supply line can lead to the pipeline through which the process water to be purified is supplied to the evaporator during operation of the process water distillation system.

[0015] Additionally or alternatively, the heat source can be configured to supply heat to the condenser. Preferably, the heat source is then connected to the condenser of the process water distillation system. For example, the heat source can be directly connected to the condenser of the process water distillation system via a heat supply line. However, alternatively, the heat supply line can lead to a line through which steam to be condensed from the evaporator is supplied to the condenser during operation of the process water distillation system.

[0016] Additionally or alternatively, the process water distillation system may include an electric heating device configured to supply heat energy to the process water distillation system. Specifically, the electric heating device is configured to supply heat energy to the evaporator. The electric heating device can perform a dual function: firstly, as a start-up heater during the preheating phase of the process water distillation system's operation; and secondly, supplying additional energy to the entire system during the distillation phase of the process water distillation system's operation, which can be used to compensate for the increase in the boiling point of the concentrate.

[0017] Preferably, the heat source is configured to supply the process water distillation system with hot gas, particularly water vapor, at a pressure above atmospheric pressure. Specifically, the heat source can be configured to supply the process water distillation system with hot gas at a pressure of at least 2 bar. Additionally or alternatively, the heat source can be configured to supply the process water distillation system with saturated water vapor. The saturated water vapor can be condensed in the condenser of the process water distillation system, thereby supplying additional energy to the process water distillation system.

[0018] Preferably, the process water distillation system further includes at least one temperature sensor configured to measure the temperature within the process water distillation system and transmit a signal representing the temperature within the process water distillation system to a control device. Multiple temperature sensors may also be provided if desired or necessary, and these sensors may be installed in different areas of the process water distillation system. Specifically, the process water distillation system may include a first temperature sensor configured to sense the temperature in the evaporator. Furthermore, a second temperature sensor may be provided, configured to sense the temperature in the condenser. For example, the second temperature sensor may be positioned to sense the temperature in the exhaust line connected to the condenser. The temperature difference between the evaporator and condenser is an indicator of heat transfer between the condenser and evaporator, and therefore an indicator of the progress of the distillation process in the process water distillation system. If the temperature difference decreases, it can be assumed that heat transfer is reduced and therefore the distillation process slows down.

[0019] Furthermore, the process water distillation system may include at least one pressure sensor configured to measure the pressure within the process water distillation system and transmit a signal representing the pressure within the process water distillation system to a control device. Multiple pressure sensors may be provided if desired or required, and these pressure sensors may be installed in different areas of the process water distillation system. Specifically, the process water distillation system may include a first pressure sensor configured to sense the pressure in the evaporator. Additionally, a second pressure sensor may be provided, configured to sense the pressure in the condenser.

[0020] Preferably, the control device is configured to control the operation of the process water distillation system based on signals transmitted by at least one temperature sensor and / or at least one pressure sensor. Specifically, the control device can use the signals transmitted by at least one temperature sensor and / or at least one pressure sensor to draw conclusions about the progress of the distillation process in the process water distillation system and accordingly control the energy supply from the energy source.

[0021] In a preferred embodiment of the process water distillation system, the control device is configured to control the operation of the process water distillation system at the start of operation during the preheating phase, namely, that the pressure in the process water distillation system is reduced to below atmospheric pressure during the depressurization step. For this purpose, the compressor is correspondingly controlled by the control device. Furthermore, the process water to be purified is supplied to the process water distillation system. To deliver the process water to the process water distillation system, the vacuum already present in the system can be used. However, alternatively, an additional delivery device, such as a diaphragm pump, can be used to deliver the process water to the process water distillation system.

[0022] Subsequently, the compressor can deliver fluid from the evaporator to the condenser in a closed recirculation loop, where the fluid is heated by compression within the compressor. As the fluid flows through the condenser, the heat energy released during condensation is transferred to the fluid in the evaporator. This heating process uses a water distillation system, particularly the evaporator.

[0023] Furthermore, under the control of the control device, thermal energy and / or hot gas can be supplied from the energy source to the process water distillation system. The additional energy provided by the energy source can shorten the time required to reach the desired operating temperature in the process water distillation system, thereby shortening the system's preheating phase.

[0024] Specifically, the control device can be configured to control the operation of the process water distillation system at the start of operation during the preheating phase in such a way that heat energy from an electrically heated device from the energy source is supplied to the evaporator of the process water distillation system. This results in additional heat input to the evaporator, thereby allowing the operating temperature required for continuous distillation in the process water distillation system to be reached more quickly. Additionally or alternatively, hot gas from a heat source from the energy source can be supplied to the condenser of the process water distillation system. This additional heat input also allows the operating temperature for continuous distillation to be reached more quickly. Furthermore, supplying hot gas to the condenser prevents the process water in the evaporator from being diluted in an undesirable manner, especially when steam is used as the hot gas.

[0025] After the preheating stage is completed, once the desired operating temperature for continuous distillation has been reached in the process water distillation system, i.e., in the evaporator and condenser, the operation of the process water distillation system can transition to the distillation stage. The control device is preferably configured to control the operation of the process water distillation system during the distillation stage in such a way that fluid recirculation between the evaporator and condenser is interrupted. This can be achieved, for example, by closing a bypass valve between the evaporator and condenser. Furthermore, under the control of the control device, the distillate can be discharged from the condenser during the distillation stage.

[0026] Meanwhile, as described above, during the distillation stage, the concentrate is collected in the concentrate collection area of ​​the process water distillation system. As distillation proceeds and thus the amount of distillate discharged from the condenser increases, the concentration of low-volatile impurities in the concentrate increases, and consequently, the boiling point of the concentrate increases. Therefore, the distillation process slows down. Depending on the progress of the distillation process in the process water distillation system, hot gas from the energy source is therefore preferably supplied to the evaporator and / or condenser of the process water distillation system under the control of a control device to compensate for the increase in the boiling point of the concentrate and to sustain the distillation process by additionally inputting energy into the system.

[0027] Specifically, the control device can be configured to control the operation of the process water distillation system during the distillation stage in such a way that when the pressure in the evaporator drops below a pressure threshold and / or the temperature in the evaporator drops below a temperature threshold, hot gas from the energy source is supplied to the evaporator of the process water distillation system. By supplying hot gas, particularly steam, the pressure and / or temperature in the evaporator can be increased, thereby maintaining the distillation process. When the temperature in the evaporator exceeds the maximum permissible value, the supply of hot gas from the energy source to the evaporator of the process water distillation system is preferably interrupted under the control of the control device.

[0028] During this operational phase of the process water distillation system, the compressor preferably operates continuously at a constant speed, such that the pressure in the evaporator is controlled substantially by supplying hot gas from the energy source to the evaporator. The temperature threshold in the evaporator may, for example, be a temperature corresponding to the temperature of the process water in the process water distillation system. Above this temperature threshold, hot gas begins to be supplied from the energy source to the evaporator under the control of the control device.

[0029] Furthermore, the control device can be configured to control the operation of the process water distillation system during the distillation stage in such a way that, when the temperature in the condenser drops below a temperature threshold, hot gas from the energy source is supplied to the condenser of the process water distillation system. By supplying hot gas, the temperature in the condenser can be increased, thereby providing heat transfer from the fluid flowing through the condenser to the fluid in the evaporator, which is necessary to maintain the distillation process in the process water distillation system. When the temperature in the condenser exceeds a permissible maximum value, the supply of hot gas from the energy source to the condenser of the process water distillation system is preferably interrupted under the control of the control device. The permissible maximum value can be, for example, a temperature above which complete condensation no longer occurs in the condenser.

[0030] Furthermore, the control system can be configured to control the operation of the process water distillation system during the distillation stage in such a way that fluid recirculation between the evaporator and condenser is interrupted, the distillate is discharged from the condenser, and simultaneously, heat energy is supplied from an electric heating device of the energy source to the evaporator of the process water distillation system. This continuous input of additional heat energy to the evaporator promotes the evaporation process in the evaporator.

[0031] Finally, the control device is preferably configured to control the operation of the process water distillation system during the compensation phase (during which the increase in the boiling point of the concentrate must be compensated to maintain the distillation process) in such a way that the pressure difference between the evaporator and the condenser is increased by the compressor until the pressure difference reaches its permissible maximum value. The compensation phase preferably begins when the distillation process can no longer be sustained, despite the input of additional energy from the energy source. The compensation phase ends when the permissible maximum pressure difference is reached and it is impossible to further advance the distillation process.

[0032] Furthermore, a method for operating a process water distillation system is described, the process water distillation system including an evaporator, a condenser, and a compressor, the compressor being configured to generate a desired pressure in at least one region of the process water distillation system during operation and to deliver steam from the evaporator to the condenser. The condenser is in thermal contact with the evaporator, such that, at least during a certain phase of operation of the process water distillation system, the heat energy released during the condensation of the steam delivered to the condenser is transferred to the fluid in the evaporator. The process water distillation system also includes a concentrate collection area and an energy source, the concentrate collection area being configured to receive concentrate generated during the operation of the process water distillation system, and the energy source being configured to supply energy to the process water distillation system. A control device controls the energy supply from the energy source to the process water distillation system according to the progress of the distillation process.

[0033] The energy source may include a heat source configured to supply heat to the process water distillation system, particularly to the evaporator and / or condenser. Preferably, the heat source includes an external steam source, such as an external steam generator, configured to supply steam to the process water distillation system. Additionally or alternatively, the energy source may include an electric heating device configured to supply heat energy to the process water distillation system, particularly to the evaporator.

[0034] The heat source is preferably configured to supply the process water distillation system with heat, particularly water vapor and / or saturated water vapor, at a pressure above atmospheric pressure, especially at a pressure of at least 2 bar.

[0035] The process water distillation system preferably further includes at least one temperature sensor configured to transmit a signal representing the temperature in the process water distillation system to a control device. Additionally or alternatively, the process water distillation system may include at least one pressure sensor configured to transmit a signal representing the pressure in the process water distillation system to the control device. The control device preferably controls the operation of the process water distillation system based on the signals transmitted by the at least one temperature sensor and / or the at least one pressure sensor.

[0036] During the preheating phase, at the start of operation, the control device can control the operation of the process water distillation system in the following manner: during the depressurization step, the pressure in the process water distillation system is reduced to below atmospheric pressure, the process water to be purified is supplied to the process water distillation system, the compressor delivers fluid from the evaporator to the condenser in a closed recirculation loop, wherein the fluid is heated by compression in the compressor and releases heat energy into the fluid in the evaporator as the fluid flows through the condenser, and heat energy and / or hot gas from the energy source are supplied to the process water distillation system.

[0037] Additionally or alternatively, during the preheating phase at the start of operation, the control device may control the operation of the process water distillation system in such a way that heat energy from an electric heating device from an energy source is supplied to the evaporator of the process water distillation system, and / or hot gas from a hot gas source from an energy source is supplied to the condenser of the process water distillation system.

[0038] During the distillation stage, the control device can control the operation of the process water distillation system in such a way that the fluid recirculation between the evaporator and the condenser is interrupted, the distillate is discharged from the condenser, and hot gas from the energy source is supplied to the evaporator and / or condenser of the process water distillation system according to the progress of the distillation process in the process water distillation system.

[0039] Additionally or alternatively, during the distillation stage, the control device can control the operation of the process water distillation system in such a way that when the pressure in the evaporator drops below a pressure threshold and / or the temperature in the evaporator drops below a temperature threshold, hot gas from the energy source is supplied to the evaporator of the process water distillation system. Under the control of the control device, when the temperature in the evaporator exceeds the maximum allowable value, the supply of hot gas from the energy source to the evaporator of the process water distillation system can be interrupted.

[0040] Furthermore, during the distillation stage, the control device can control the operation of the process water distillation system in such a way that when the temperature in the condenser drops below a threshold, water vapor from an external steam generator of the energy source is supplied to the condenser of the process water distillation system. Under the control of the control device, when the temperature in the condenser exceeds the maximum allowable value, the supply of hot gas from the energy source to the condenser of the process water distillation system can be interrupted.

[0041] Furthermore, during the distillation stage, the control device can control the operation of the process water distillation system in such a way that the fluid recirculation between the evaporator and the condenser is interrupted, the distillate is discharged from the condenser, and heat energy from the electric heating device of the energy source is supplied to the evaporator of the process water distillation system.

[0042] During the compensation phase, the control device can control the operation of the process water distillation system in such a way that the pressure difference between the evaporator and the condenser is increased by the compressor until the pressure difference reaches the maximum allowable value. Attached Figure Description

[0043] The preferred embodiments of the invention will now be explained in more detail with reference to the accompanying schematic diagrams, wherein...

[0044] Figure 1 The process water distillation system is shown. Detailed Implementation

[0045] Figure 1 The process water distillation system 10 shown includes a distillation vessel 12 having a first vessel section 12a, a second vessel section 12b, and a third vessel section 12c. The process water to be purified may contain impurities such as silicones, siloxanes, glycols, emulsifiers, surfactants, salts, and light liquids such as gasoline, benzene, lubricants, or oils, and is supplied to the first vessel section 12a of the distillation vessel 12 via a process water supply line 14.

[0046] Tube bundle 16 is disposed in the second container section 12b. In the evaporator 18 located in the region of the receiving tube bundle 16 in the second container section, process water is heated and evaporated, with low-volatility impurities collected in the concentrate collection area 20 of the first container section 12a. The concentrate collection area 20 is disposed in a storage tank of the first container section 12a. During operation of the process water distillation system 10, the concentrate collection area 20 of the first container section 12a is mixed with process water supplied to the first container section 12a via the process water supply line 14, such that the concentrated process water can be conveyed from the first container section 12a to the evaporator 18 via the supply line 24. After the distillation process is complete, the concentrate can be discharged from the concentrate collection area 20 of the first container section 12a via the concentrate discharge line 26 from the distillation vessel 12 via the first conveying device 25.

[0047] In the process water distillation system 10 shown herein, evaporation occurs at a pressure reduced compared to atmospheric pressure, where a compressor 28, designed here as a vapor compressor, ensures that the desired pressure conditions are set in the process water distillation system 10. A pulsation damper 30 is provided downstream of the compressor 28. During operation of the process water distillation system 10, water vapor formed in the evaporator 18 fills a portion of the first container section 12a and the third container section 12c. The water vapor passes through a demister 32 provided in the third container section 12c and is delivered to the condenser 34 via the compressor 28.

[0048] The condenser 34 is defined by the internal volume of the tubes of the tube bundle 14, around which the fluid to be evaporated in the evaporator flows during operation of the process water distillation system 10. The condenser 34 is thus in thermal contact with the evaporator 18, such that, at least during certain operating phases of the process water distillation system 10, the heat energy released during the condensation of the vapor delivered to the condenser 34 can be transferred to the fluid in the evaporator 18.

[0049] The distillate, cooled and condensed in condenser 34, eventually enters heat exchanger 38 via connecting conduit 36, where it is further cooled. In heat exchanger 38, the distillate comes into thermal contact with the process water to be supplied to the distillation vessel 12 of the process water distillation system 10. Therefore, in the process water distillation system 10, heat exchanger 38 serves as a process water preheater / distillate cooler. After flowing through heat exchanger 38, the distillate is discharged from the process water distillation system 10 via distillate discharge line 39.

[0050] Furthermore, the process water distillation system 10 includes an energy source configured to supply energy to the process water distillation system 10. In an embodiment of the process water distillation system 10 shown herein, the energy source includes a hot gas source 41 configured as an external steam source or external steam generator to supply hot gas (i.e., water vapor) to the process water distillation system 10. The hot gas source 41 is configured to supply hot gas, i.e., water vapor and / or saturated water vapor, having a pressure of at least 2 bar above atmospheric pressure to the process water distillation system 10.

[0051] A heat source 41 is connected to the evaporator 18 via a first heat supply line 44 and to the condenser 34 via a second heat supply line 45. Specifically, the first heat supply line 44 leads to the upper region of the third container section 12c, which is filled with water vapor during operation of the process water distillation system 10. Alternatively, however, the first heat supply line 44 may lead to the line through which the process water to be purified is supplied to the evaporator 18 during operation of the process water distillation system 10. For example, it is also conceivable to connect the first heat supply line 44 upstream of the evaporator 18 to the supply line 24.

[0052] The second hot gas supply line 45, downstream of the compressor 28 and downstream of the pulsation damper 30, leads to the steam discharge line 46 that connects the evaporator 18 to the condenser 34. Alternatively, the second hot gas supply line 45 may also be directly connected to the condenser 34 and, for example, lead to one of the plurality of pipes in the tube bundle 16.

[0053] Furthermore, the energy source includes an electric heating device 47, which is configured to supply heat energy to the process water distillation system 10. In the embodiment of the process water distillation system 10 shown herein, the electric heating device 47 is disposed in the concentrate collection area 20, i.e., in the storage tank of the first container section 12a, and is thereby configured to supply heat energy to the evaporator 18.

[0054] The operation of the process water distillation system 10 is controlled by a control device 49. Among other things, the control device 49 is configured to control the energy supply from an energy source, which includes a heat source 41 and an electric heating device 47, to the process water distillation system 10. For this purpose, the control device 49 accordingly controls the heat source 41, a first heat supply valve 50 arranged in a first heat supply line 44, and a second heat supply valve 51 arranged in a second heat supply line 45, so as to allow or interrupt the generation of heat in the heat source 41, and, as needed, allow or interrupt the conduction of the generated heat from the heat source 41 to the evaporator 18 or the condenser 34.

[0055] The process water distillation system 10 also includes at least one temperature sensor 52, 54, configured to measure the temperature within the process water distillation system 10 and transmit a signal representing the temperature within the process water distillation system 10 to the control device 49. Specifically, the process water distillation system 10 includes a first temperature sensor 54 for sensing the temperature in the evaporator 18. A second temperature sensor 54 is used to sense the temperature in the condenser 34. Here, the second temperature sensor 54 is located in the exhaust line 55 connected to the condenser 34.

[0056] Furthermore, the process water distillation system 10 includes at least one pressure sensor 56, 58, configured to measure the pressure in the process water distillation system 10 and transmit a signal representing the pressure in the process water distillation system 10 to the control device 49. Specifically, the process water distillation system 10 includes a first pressure sensor 56 and a second pressure sensor 58, the first pressure sensor for sensing the pressure in the evaporator 18 and the second pressure sensor for sensing the pressure in the condenser 34. The control device 49 controls the operation of the process water distillation system 10 based on the signals transmitted by the sensors 52, 54, 56, 58. Specifically, the control device 49 determines the progress of the distillation process in the process water distillation system 10 based on the signals transmitted by the sensors 52, 54, 56, 58, and accordingly controls the energy supply from the energy source, namely, the operation of the hot gas source 41 and the operation of the electric heating device 47.

[0057] During the preheating phase, at the start of operation of the process water distillation system 10, the control device 49 controls the operation of the process water distillation system 10 in the following manner: First, in the pressure reduction step, the pressure in the process water distillation system 10 is reduced to below atmospheric pressure by corresponding control of the compressor 28. Furthermore, under the control of the control device 49, process water is supplied to the process water distillation system 10 by opening the process water supply valve 59 arranged in the process water supply line 14 and utilizing the negative pressure established in the process water distillation system 10. This supplies the process water to be purified to the process water distillation system 10.

[0058] During the preheating phase, a bypass valve 60 located in the bypass line 62 connecting the evaporator 18 to the condenser 34 is opened. The compressor 28 thus delivers fluid from the evaporator 18 to the condenser 34 in a closed recirculation loop. The fluid heated by compression in the compressor 28 condenses as it flows through the condenser 34. The heat released during condensation is transferred to the fluid awaiting evaporation in the evaporator 18. This heating process uses the water distillation system 10, particularly the evaporator 18.

[0059] During the preheating phase, the preheating process is assisted by supplying heat energy and / or hot gas to the process water distillation system 10 under the control of the control device 49. Specifically, during the preheating phase, the electric heating device 47 is operated under the control of the control device 49, causing it to release heat energy to the evaporator 18. Therefore, during the preheating phase, the electric heating device 47 serves as a start-up heater. Furthermore, under the control of the control device 49, the hot gas source 41 is operated, and hot gas is supplied to the condenser 34 of the process water distillation system 10 by opening the second hot gas supply valve 51. By supplying additional energy to the process water distillation system 10, the operating temperature required for continuous distillation in the process water distillation system 10 can be reached more quickly, thereby shortening the start-up process.

[0060] After the preheating stage is completed, i.e., when the desired operating temperature for continuous distillation is reached in the process water distillation system 10, the operation of the process water distillation system 10 transitions to the distillation stage. For this purpose, under the control of the control device 49, the bypass valve 60 is first closed, thereby interrupting the fluid recirculation between the evaporator 18 and the condenser 34. Furthermore, under the control of the control device 49, the distillate discharge valve 64, located in the connecting line 36, is opened, allowing the distillate to be discharged from the condenser 34.

[0061] During the distillation stage, the concentrate is collected in the concentrate collection area 20, and as distillation proceeds and the distillate is thus discharged from the condenser 34, the concentration of low-volatile impurities in the concentrate increases, and therefore the boiling point of the concentrate increases. Consequently, the distillation process slows down. Therefore, based on the progress of the distillation process in the process water distillation system 10 monitored by sensors 52, 54, 56, and 58, hot gas is supplied from the hot gas source 41 to the evaporator 18 and / or condenser 34 of the process water distillation system under the control of the control device 49. Furthermore, under the control of the control device 49, the electric heating device 47 remains operational, thereby introducing additional heat energy from the electric heating device 47 into the evaporator 18. This additional energy input to the system can compensate for the increase in the boiling point of the concentrate for at least a certain period of time and sustain the distillation process.

[0062] As described above, during the preheating stage, hot gas from the heat source 41 is not supplied to the evaporator 18, but only to the condenser 34, to prevent the process water to be evaporated from being diluted by the hot gas supplied by the heat source 41 (i.e., water vapor generated by the steam generator). On the other hand, during the distillation stage, the hot gas generated by the heat source 41 can be supplied to either the evaporator 18 or the condenser 34. In order to supply the hot gas generated by the heat source 41 to the evaporator 18, under the control of the control device 49, the first hot gas supply valve 50 arranged in the first hot gas supply line 44 is opened, while the second hot gas supply valve 51 arranged in the second hot gas supply line 45 is closed. On the other hand, by opening the second hot gas supply valve 51 while the first hot gas supply valve 50 is closed, steam is supplied from the heat source 41 to the condenser 34 as described above.

[0063] When the pressure in evaporator 18 drops below a pressure threshold and / or the temperature in evaporator 18 drops below a temperature threshold, hot gas is supplied from heat source 41 to evaporator 18 during the distillation phase under the control of control device 49. The temperature threshold in evaporator 18 may be, for example, a temperature corresponding to the temperature of the process water in process water distillation system 10; below this temperature threshold, hot gas is supplied from heat source 41 to evaporator 18. During the distillation phase, compressor 48 operates continuously at a constant speed, such that the pressure in evaporator 18 is essentially controlled by the supply of hot gas from heat source 41 to evaporator 18. By supplying hot gas, particularly steam, the pressure and temperature in evaporator 18 can be increased, thus allowing the distillation process to be maintained for a longer period even if the boiling point of the concentrate in concentrate collection zone 20 increases. When the temperature in evaporator 18 exceeds the maximum permissible value, the supply of hot gas from heat source 41 to evaporator 18 is interrupted.

[0064] When the temperature in condenser 34 drops below a temperature threshold, hot gas is supplied from heat source 41 to condenser 34 during the distillation stage under the control of control device 49. By supplying hot gas, particularly steam, the temperature in condenser 34 can be increased, thereby ensuring heat transfer from the fluid flowing through condenser 34 to the fluid in the evaporator, which is necessary to maintain the distillation process in the process water distillation system. On the other hand, when the temperature in condenser 34 exceeds a permissible maximum value, the hot gas supply from heat source 41 to condenser 34 of the process water distillation system is interrupted under the control of control device 49. The permissible maximum value is selected as a temperature above which complete condensation no longer occurs in condenser 34.

[0065] In the operation of the process water distillation system 10, a compensation phase follows the distillation stage. This compensation phase begins when the distillation process can no longer be sustained, despite the input of additional energy from the energy source. During the compensation phase (during which the increase in the boiling point of the concentrate must be compensated for to maintain the distillation process), the control device 49 controls the operation of the process water distillation system 10, and in particular controls the operation of the compressor 28 in such a way that the pressure difference between the evaporator 18 and the condenser 34 is increased by the compressor until the pressure difference reaches a permissible maximum value. The permissible maximum value of the pressure difference between the evaporator 18 and the condenser 34 is, for example, determined by the design of the process water distillation system 10. When the permissible maximum value of the pressure difference is reached and the distillation process can no longer be further promoted, the compensation phase, and thus the entire distillation process, ends.

Claims

1. A process water distillation system (10), comprising: - Evaporator (18) - Condenser (34). - Compressor (28), the compressor being configured to generate a desired pressure in at least one region of the process water distillation system (10) during operation of the process water distillation system (10) and to deliver steam from the evaporator (18) to the condenser (34); the condenser (34) being in thermal contact with the evaporator (18) such that, at least during a certain phase of operation of the process water distillation system (10), the heat energy released during the condensation of the steam delivered to the condenser (34) is transferred to the fluid in the evaporator (18). - Concentrate collection area (20), which is configured to receive concentrates generated during the operation of the process water distillation system (10). - An energy source configured to supply energy to the process water distillation system (10), - Control device (49), the control device being configured to control the energy supply from the energy source to the process water distillation system (10) according to the progress of the distillation process in the process water distillation system (10), and - At least one temperature sensor (52, 54) configured to transmit a signal representing the temperature in the process water distillation system (10) to the control device (49). The energy source includes a heat source (41) configured to supply heat to the process water distillation system (10), and the heat source (41) includes an external steam source configured to supply steam to the process water distillation system (10). The control device (49) is configured such that: (i) During the distillation stage, when the pressure in the evaporator (18) drops below a pressure threshold and / or the temperature in the evaporator (18) drops below a temperature threshold, water vapor from an external steam source of the energy source is supplied to the evaporator (18) of the process water distillation system (10); and (ii) During the distillation stage, when the temperature in the condenser (34) drops below the temperature threshold, water vapor from an external steam source of the energy source is supplied to the condenser (34) of the process water distillation system (10).

2. The process water distillation system (10) according to claim 1, wherein, The heat source is configured to supply the heat to the evaporator (18) and / or the condenser (34).

3. The process water distillation system (10) according to claim 1, wherein: - The energy source includes an electric heating device (47) configured to supply heat energy to the process water distillation system (10).

4. The process water distillation system (10) according to claim 3, wherein, The electric heating device is configured to supply heat energy to the evaporator (18).

5. The process water distillation system (10) according to claim 3, wherein, The heat source (41) is configured to supply hot gas at a pressure above atmospheric pressure and / or saturated steam to the process water distillation system (10).

6. The process water distillation system (10) according to claim 5, wherein, The heat source (41) is configured to supply heat at a pressure of at least 2 bar to the process water distillation system (10).

7. The process water distillation system (10) according to claim 5, wherein, The hot gas described is water vapor, which is heated at a pressure higher than atmospheric pressure.

8. The process water distillation system (10) according to claim 1, further comprising: - At least one pressure sensor (56, 58) configured to transmit a signal representing the pressure in the process water distillation system (10) to the control device (49). The control device (49) is configured to control the operation of the process water distillation system (10) based on signals transmitted by the at least one temperature sensor (52, 54) and / or the at least one pressure sensor (56, 58).

9. The process water distillation system (10) according to claim 1, wherein, The control device (49) is configured to control the operation of the process water distillation system (10) at the start of operation during the preheating phase in such a way as follows: - In the depressurization step, the pressure in the process water distillation system (10) is reduced to below atmospheric pressure. - The process water to be purified is supplied to the process water distillation system (10). - The compressor (28) delivers fluid from the evaporator (18) to the condenser (34) in a closed recirculation loop, wherein the fluid is heated by compression in the compressor (28) and releases heat to the fluid in the evaporator (18) as it flows through the condenser (34), and - Thermal energy and / or hot gas from the energy source are supplied to the process water distillation system (10).

10. The process water distillation system (10) according to claim 9, wherein, The control device (49) is configured to control the operation of the process water distillation system (10) at the start of operation during the preheating phase in such a way as follows: - Thermal energy from the electric heating device (47) of the energy source is supplied to the evaporator (18) of the process water distillation system (10), and / or - Hot gas from the heat source (41) of the energy source is supplied to the condenser (34) of the process water distillation system (10).

11. The process water distillation system (10) according to claim 1, wherein, The control device (49) is configured to control the operation of the process water distillation system (10) during the distillation stage in the following manner: - The recirculation of fluid between the evaporator (18) and the condenser (34) is interrupted. - The distillate is discharged from the condenser (34), and - Hot gas from the hot gas source (41) of the energy source is supplied to the evaporator (18) and / or condenser (34) of the process water distillation system (10) according to the progress of the distillation process in the process water distillation system (10).

12. The process water distillation system (10) according to claim 11, wherein, The control device (49) is configured to control the operation of the process water distillation system (10) during the distillation stage in the following manner: When the temperature in the evaporator (18) exceeds the maximum allowable value, the supply of hot gas from the heat source (41) of the energy source to the evaporator (18) of the process water distillation system (10) is interrupted.

13. The process water distillation system (10) according to claim 11, wherein, The control device (49) is configured to control the operation of the process water distillation system (10) during the distillation stage in the following manner: When the temperature in the condenser (34) exceeds the maximum allowable value, the supply of hot gas from the heat source (41) of the energy source to the condenser (34) of the process water distillation system (10) is interrupted.

14. The process water distillation system (10) according to claim 1, wherein, The control device (49) is configured to control the operation of the process water distillation system (10) during the distillation stage in the following manner: - The recirculation of fluid between the evaporator (18) and the condenser (34) is interrupted. - The distillate is discharged from the condenser (34), and - Thermal energy from the electric heating device (47) of the energy source is supplied to the evaporator (18) of the process water distillation system (10).

15. The process water distillation system (10) according to claim 1, wherein, The control device (49) is configured to control the operation of the process water distillation system (10) during the compensation phase in the following manner: The pressure difference between the evaporator (18) and the condenser (34) is increased by the compressor (28) until the pressure difference reaches the maximum allowable value.

16. A method for controlling a process water distillation system (10), the process water distillation system comprising: - Evaporator (18) - Condenser (34). - Compressor (28), the compressor being configured to generate a desired pressure in at least one region of the process water distillation system (10) during operation of the process water distillation system (10) and to deliver steam from the evaporator (18) to the condenser (34); the condenser (34) being in thermal contact with the evaporator (18) such that, at least during a certain phase of operation of the process water distillation system (10), the heat energy released during the condensation of the steam delivered to the condenser (34) is transferred to the fluid in the evaporator (18). - Concentrate collection area (20), which is configured to receive concentrates generated during the operation of the process water distillation system (10). - An energy source configured to supply energy to the process water distillation system (10), - At least one temperature sensor (52, 54) configured to transmit a signal representing the temperature in the process water distillation system (10) to the control device (49). The control device (49) controls the energy supply from the energy source to the process water distillation system (10) based on the progress of the distillation process in the process water distillation system (10). The energy source includes a heat source (41) configured to supply heat to the process water distillation system (10), and the heat source (41) includes an external steam source configured to supply steam to the process water distillation system (10). The control device (49) controls the operation of the process water distillation system (10) during the distillation stage in the following manner: (i) When the pressure in the evaporator (18) drops below a pressure threshold and / or the temperature in the evaporator (18) drops below a temperature threshold, water vapor from an external steam source of the energy source is supplied to the evaporator (18) of the process water distillation system (10); and (ii) When the temperature in the condenser (34) drops below the temperature threshold, water vapor from an external steam source from the energy source is supplied to the condenser (34) of the process water distillation system (10).

17. The method according to claim 16, wherein, The heat source is configured to supply heat to the evaporator (18) and / or the condenser (34).

18. The method of claim 16, wherein: - The energy source includes an electric heating device (47) configured to supply heat energy to the process water distillation system (10).

19. The method according to claim 18, wherein, The electric heating device is configured to supply heat energy to the evaporator (18).

20. The method according to claim 18, wherein, The heat source (41) is configured to supply hot gas at a pressure above atmospheric pressure and / or saturated steam to the process water distillation system (10).

21. The method according to claim 20, wherein, The heat source (41) is configured to supply heat at a pressure of at least 2 bar to the process water distillation system (10).

22. The method according to claim 20, wherein, The hot gas described is water vapor, which is heated at a pressure higher than atmospheric pressure.

23. The method according to claim 16, wherein, The process water distillation system (10) further includes: - At least one pressure sensor (56, 58) configured to transmit a signal representing the pressure in the process water distillation system (10) to the control device (49). The control device (49) controls the operation of the process water distillation system (10) based on signals transmitted by the at least one temperature sensor (52, 54) and / or the at least one pressure sensor (56, 58).

24. The method of claim 16, wherein: The control device (49) controls the operation of the process water distillation system (10) at the start of operation during the preheating phase in the following manner: - In the depressurization step, the pressure in the process water distillation system (10) is reduced to below atmospheric pressure. - The process water to be purified is supplied to the process water distillation system (10). - The compressor (28) delivers fluid from the evaporator (18) to the condenser (34) in a closed recirculation loop, wherein the fluid is heated by compression in the compressor (28) and releases heat to the fluid in the evaporator (18) as it flows through the condenser (34), and - Thermal energy and / or hot gas from the energy source are supplied to the process water distillation system (10), and / or The control device (49) controls the operation of the process water distillation system (10) at the start of operation during the preheating phase in the following manner: - Thermal energy from the electric heating device (47) of the energy source is supplied to the evaporator (18) of the process water distillation system (10), and / or - Hot gas from the heat source (41) of the energy source is supplied to the condenser (34) of the process water distillation system (10).

25. The method according to claim 16, wherein: The control device (49) controls the operation of the process water distillation system (10) during the distillation stage in the following manner: - The recirculation of fluid between the evaporator (18) and the condenser (34) is interrupted. - The distillate is discharged from the condenser (34), and - Hot gas from the heat source (41) of the energy source is supplied to the evaporator (18) and / or condenser (34) of the process water distillation system (10) according to the progress of the distillation process in the process water distillation system (10), and / or The control device (49) controls the operation of the process water distillation system (10) during the distillation stage in the following manner: - When the temperature in the evaporator (18) exceeds the maximum allowable value, the supply of hot gas from the heat source (41) of the energy source to the evaporator (18) of the process water distillation system (10) is interrupted, and / or The control device (49) controls the operation of the process water distillation system (10) during the distillation stage in the following manner: - When the temperature in the condenser (34) exceeds the maximum allowable value, the supply of hot gas from the heat source (41) of the energy source to the condenser (34) of the process water distillation system (10) is interrupted, and / or The control device (49) controls the operation of the process water distillation system (10) during the distillation stage in the following manner: - The recirculation of fluid between the evaporator (18) and the condenser (34) is interrupted. - The distillate is discharged from the condenser (34), and - Thermal energy from the electric heating device (47) of the energy source is supplied to the evaporator (18) of the process water distillation system (10).

26. The method of claim 16, wherein: The control device (49) controls the operation of the process water distillation system (10) during the compensation phase in the following manner: The pressure difference between the evaporator (18) and the condenser (34) is increased by the compressor (28) until the pressure difference reaches the maximum allowable value.

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