Fluid concentration device and fluid concentration method

Abstract

1. A method for concentrating a process fluid, comprising: (a) maintaining a process fluid at a predetermined temperature value or temperature range; (b) evaporating a carrier fluid from the process fluid to obtain a concentrated process fluid; (c) monitoring at least one process variable of step (a) or (b) to detect fouling formed in either step (a) or (b); (d) reducing the formed fouling by initiating a cleaning protocol when the process variable falls outside a predetermined value or range; A method comprising:

Description

[Technical Field]

[0001] The present invention relates to an apparatus and method for concentrating a process fluid, such as sugarcane juice or wastewater.

[0002] The present invention particularly, but by no means exclusively, relates to a process fluid concentrator and method for minimizing process downtime.

[0003] The present invention is particularly (Appendix The present invention relates to, but is by no means limited to, a process fluid concentrator and method for minimizing the buildup of deposits of debris (fouling, dirt, etc.). [Background technology]

[0004] In the sugar industry, sugar is generally produced by extracting sugarcane juice and concentrating the juice until the concentrated juice becomes crystalline sugar.

[0005] A common method involves crushing sugarcane to obtain sugarcane juice, which is then concentrated by heating at high temperatures. One of the problems with this method is that the heating process can cause browning or caramelization of the juice due to, for example, the breakdown of polysaccharides into monosaccharides. To address this problem, lime (CaO) is added to clarify the final product. (Clarification) and make it white.

[0006] Another problem faced by sugar refinery operators is the susceptibility of process equipment to fouling due to the deposition of sugars and impurities from the sugarcane juice onto the equipment. The impurities include organic impurities such as proteins and inorganic impurities such as calcium- and silicon-containing minerals. Therefore, the process must be stopped periodically to manually clean the process equipment in order to maintain the quality and yield of the final product.

[0007] Attempts to avoid browning of the sugarcane juice have been made by evaporating at lower temperatures, but this slows down the evaporation rate, lengthening the processing time and still necessitating periodic interruptions to manually clean the process equipment.

[0008] It would be desirable to provide a method for concentrating process fluids, such as sugarcane juice, that reduces process downtime. Summary of the Invention

[0009] The present invention provides an improved method and apparatus for concentrating a process fluid.

[0010] The present invention is, at least in part, directed to reducing the fouling of process fluids while reducing fouling of process equipment. (mixture) This is accomplished by conducting the process under optimum conditions to concentrate the hydroxybenzoates, which may include controlling the temperature of the process fluid.

[0011] The present invention provides improved drift removal in mass transfer media (e.g., air) lines and / or carrier fluid (e.g., argon) in process fluids. solvent, For example, by providing evaporation-fill-less evaporation of water, fouling buildup can be proactively reduced.

[0012] The present invention also includes an automatic cleaning system that allows for cleaning of liquid lines containing at least one heat exchanger, further enabling the present invention to handle process fluids containing fouling substances or to eliminate the need for manual cleaning of process equipment.

[0013] As used herein, mass transfer medium refers to a fluid (usually air) that facilitates mass transfer of a carrier fluid (e.g., water) from a process fluid stream into the mass transfer medium, and heat transfer may occur in the process.

[0014] As used herein, heat transfer medium refers to a fluid (eg, water) that receives heat from or transfers heat to a process fluid.

[0015] The cleaning system is a cleaning protocol (stain removal treatment) According to Antifouling agent The system may include one or more storage tanks, valves, and pumps for storing the antifouling agent, which is circulated through the system to remove fouling from process equipment.

[0016] The cleaning protocol is based on the predetermined process variables. (parameter) may start when the thresholds fall outside their ranges.

[0017] The cleaning protocol may be initiated when a predetermined process variable exceeds a threshold range.

[0018] Cleaning protocols can be performed on a timed cycle or when sludge / scale buildup is detected.

[0019] The apparatus may include a controller in communication with a plurality of sensors that monitor process variables in various portions of the process. Preferably, the controller is a programmable logic controller.

[0020] The device may include one or more of a pressure sensor, a flow sensor, a temperature sensor, a humidity sensor, and a level sensor.

[0021] The apparatus may include pressure and flow sensors to detect fouling in process fluid, water, and air lines connected to, for example, an evaporator or heat exchanger of the apparatus, and when the sensors detect that the pressure or flow rate falls outside a predetermined threshold / threshold range, the controller initiates a cleaning protocol to remove the fouling from the apparatus.

[0022] Although the present invention is particularly suitable for the processing of sugarcane juice, the present invention is equally suitable for other applications, including the treatment of wastewater and the production of distilled water as a process by-product. Thus, although this specification primarily focuses on the application of the present invention to sugarcane processing, it will be understood that the present invention is not limited to that application.

[0023] The present invention is also suitable for zero liquid discharge of various process fluids, such as waste liquid from drying tanks and in-process fluid streams.

[0024] The cleaning system of the present invention is also applicable to energy-saving configurations, which may include pre-cooling / energy recovery heat exchangers in one or more of the process fluid lines, air lines, and water lines, which only affect the energy efficiency of the process and not the anti-fouling properties.

[0025] The present invention provides a method for concentrating a process fluid comprising: (a) maintaining a process fluid at a predetermined temperature value or temperature range; (b) evaporating the carrier fluid from the process fluid to obtain a concentrated process fluid; (c) monitoring at least one process variable of step (a) or (b) to detect fouling formed in either step (a) or (b); (d) initiating a cleaning protocol to reduce formed fouling when the process variable falls outside a predetermined value or range; The present invention provides a method comprising:

[0026] Process fluids include homogeneous solutions obtained from a process as well as heterogeneous mixtures (eg, sugar solutions obtained by crushing sugarcane or waste streams from a sugar refinery).

[0027] The carrier fluid may be a solvent capable of dissolving the solute, or the liquid medium of a suspension or slurry. Preferably, the carrier fluid is water.

[0028] Step (a) may include supplying the process fluid to a heat exchanger to maintain the process fluid at a predetermined temperature value or temperature range.

[0029] The process variables may be one or more of temperature, pressure, flow rate, humidity, and liquid level. Preferably, the process variables are pressure drop across the process equipment and mass transfer medium and process fluid flow rates.

[0030] Step (b) may include feeding the process fluid from the heat exchanger to an evaporator, which allows at least a portion of the carrier fluid to be evaporated.

[0031] Step (b) may include heating the carrier fluid without the use of an external heating source, meaning that the process fluid may be heated using heat generated by the process (e.g., by using a heat exchanger), but not using an external heater.

[0032] Step (b) may include condensing the evaporated carrier fluid.

[0033] Step (c) may include monitoring the pressure differential across the heat exchanger.

[0034] Step (c) may include monitoring the fluid flow rate through the evaporator. Preferably, step (c) includes monitoring the mass transfer medium flow rate and / or the process fluid flow rate through the evaporator.

[0035] Step (b) may involve directly contacting the process fluid with the mass transfer medium.

[0036] The mass transfer medium may be a gas. Preferably, the mass transfer medium is air.

[0037] When the mass transfer medium is a gas, the method may include humidifying the gas entering the evaporator by bubbling the gas through water.

[0038] When the mass transfer medium is a gas, the method may include spraying the process fluid onto an evaporation fill material.

[0039] Step (d) may include initiating a cleaning protocol when the pressure or flow rate falls outside a predetermined value or range to reduce fouling in the heat exchanger or evaporator.

[0040] Preferably, evaporation occurs at a temperature that does not degrade the process fluid or increase fouling of process equipment. For example, when processing sugarcane juice, evaporation occurs at a temperature in the range of 20-40°C. Temperatures in the range of 20-40°C have been found to avoid browning of the sugarcane juice and minimize sugar deposition on process equipment. In other embodiments, evaporation occurs under ambient conditions.

[0041] The process fluid may be an in-process liquid, such as sugarcane extract or wastewater.

[0042] The process fluid may be maintained at a temperature not exceeding 40°C using a heat exchanger. This ensures that the process fluid is at a temperature that does not cause excessive fouling or decomposition of the process fluid as it is concentrated in the evaporator. For example, if the process fluid is a sugar solution, the temperature may be maintained at a maximum of 20-40°C to ensure that polysaccharides in the solution do not decompose into disaccharides or monosaccharides, or to minimize caramelization.

[0043] The process fluid may be maintained at a predetermined temperature value / temperature range by countercurrent heat exchange.

[0044] The present invention also provides a method for producing concentrated sugar from sugar cane, comprising the steps of: (a) obtaining a sugar-containing extract from sugarcane; (b) maintaining the extract at a predetermined temperature value or temperature range; (c) clarifying the extract without adding lime; (d) evaporating water from the extract to form concentrated sugars; (e) monitoring the process variables of step (b) or (d) to detect fouling formed in either step (b) or (d); (f) initiating a cleaning protocol to reduce formed fouling when the process variable falls outside a predetermined value or range; The present invention provides a method comprising:

[0045] Step (a) may comprise crushing the sugarcane to obtain a sugar-containing extract (i.e., sugarcane juice). Suitably, the sugar-containing extract is formed by mixing crushed sugarcane with water.

[0046] Step (b) may comprise feeding the extract into a heat exchanger to maintain the extract at a predetermined temperature value or temperature range.

[0047] Step (d) may include feeding the extract from the heat exchanger to an evaporator.

[0048] Step (d) may include condensing the evaporated water.

[0049] Step (e) may include monitoring the pressure differential across the heat exchanger and the mass transfer medium flow rate and / or process fluid flow rate through the evaporator.

[0050] Step (f) may include initiating a cleaning protocol when the pressure or flow rate falls outside a predetermined value or range to reduce fouling in the heat exchanger or evaporator.

[0051] The evaporation step may include spraying the process fluid onto an evaporation packing and directing an airflow in a countercurrent direction through the evaporation packing. One disadvantage of this method is that the packing is prone to fouling and is difficult to clean.

[0052] A separate evaporation step is performed by transferring the mass transfer medium, preferably a bubble plate. (foam bell board) The mass transfer medium may be humidified by bubbling the mass transfer medium through water before introducing the humidified mass transfer medium into the air stream. One advantage of this method is reduced fouling and simplified maintenance of the bubble plate, e.g., with a wire brush. However, this method reduces process efficiency compared to processes using evaporative packing, typically by about 20%. This method also may increase the pressure head of a pump, preferably a fan.

[0053] The method may include recirculating a portion of the mass transfer medium (e.g., air) exiting the evaporator. Suitably, the method comprises: From the evaporator discharge will be Mass transfer medium in the drift chamber (Chamber) Circulate it inside and accompany it (carried along with the mass transfer medium)Removing the process fluid includes returning the mass transfer medium to the evaporator.

[0054] The method may include directing a portion of the mass transfer medium from the evaporator into a drift chamber to remove entrained process fluid (e.g., sugar-containing extract) before returning the purified mass transfer medium to the evaporator, thereby reducing fouling of the heat exchanger. The heat exchanger may be the evaporator coil of a heating, ventilation, and air conditioning (HVAC) system.

[0055] The method may include circulating the purified mass transfer medium through a heat exchanger before returning the purified mass transfer medium to the evaporator.

[0056] The method may include using sensors to monitor process variables of process equipment used in the method. Suitably, the method includes using sensors to monitor the pressure differential across a heat exchanger and the flow rate of the mass transfer medium and / or process fluid (e.g., sugar cane extract) in an evaporator.

[0057] When the system includes a chiller having a condenser and an evaporator coil, the flow / pressure on the liquid side of the evaporator coil or the flow and / or pressure on the vapor side of the condenser may be monitored.

[0058] Fouling on either the hot or cold side of the heat exchanger has been observed to increase the pressure differential across the heat exchanger, and when the pressure differential exceeds an acceptable threshold, a control or manual operator initiates a cleaning protocol.

[0059] The method may include humidifying the mass transfer medium prior to contact with the process fluid. The use of humidified air enhances the fouling reduction capabilities of the method.

[0060] The step of humidifying the mass transfer medium may include passing the mass transfer medium through water as bubbles, preferably using a bubble plate.

[0061] The relative humidity of the mass transfer medium may be in the range of 90 to 100%, and preferably in the range of 95 to 100%.

[0062] The method may include monitoring whether a process variable falls outside a predetermined value or range. Preferably, the method includes monitoring whether a pressure differential across a heat exchanger falls outside a predetermined range. For example, the method may determine scale / fouling buildup in a heat exchanger by measuring the normal differential pressure (PD) (e.g., 35 kPa) of the heat exchanger for a particular fluid (e.g., water) at a particular flow rate (e.g., 15 L / min, depending on the size of the heat exchanger) and monitoring for an increase in PD (for a particular flow rate for a particular fluid).

[0063] The method may include stopping the flow of process fluid into the evaporator before the start of the cleaning protocol. Preferably, the method may include redirecting the process fluid into a storage tank before the start of the cleaning protocol, thereby ensuring that the antifouling agent does not mix with and contaminate the process fluid.

[0064] The cleaning protocol may trigger a longer self-cleaning and / or release of stronger cleaning antifouling agents (eg, hotter water, more concentrated acid or base solutions).

[0065] For a 250 L / day experimental apparatus, the predetermined pressure value or pressure range of the heat exchanger may be in the range of 5 to 50 kPa, preferably in the range of 10 to 45 kPa, and more preferably 45 kPa. Preferably, the predetermined pressure value or pressure range may be linearly scalable depending on the capacity of the apparatus. The predetermined pressure value or pressure range may depend on the heat exchange method.

[0066] For a 250 L / day experimental system, the predetermined value or range of mass transfer medium flow rate for the evaporator may be in the range of 10-20 L / min, preferably 15 L / min. It has been determined that evaporator fouling can result in a reduction in the mass transfer medium flow rate through the evaporator. Therefore, when the flow rate drops below an acceptable threshold, the controller initiates a cleaning protocol. Preferably, the acceptable threshold may be a decrease of at least 0.5 L / min. The predetermined value or range of mass transfer medium flow rate for the evaporator may be linearly scalable with the capacity of the system.

[0067] The predetermined value or range of the process fluid flow rate of the evaporator may be in the range of 0.10 to 0.30 L / min, and is preferably in the range of 0.15 to 0.25 L / min.

[0068] The cleaning protocol involves the use of an antifouling solution (Anti-fouling liquid) through one or more pieces of process equipment used in the method. Preferably, the cleaning protocol includes circulating the antifouling liquid through the heat exchanger until the pressure returns to a predetermined value or range.

[0069] The antifouling liquid may be water, an acidic solution, or a basic solution. Preferably, the solution is food grade.

[0070] When the antifouling liquid is water, the water may be maintained at a temperature in the range of 20 to 40° C. Preferably, the water is maintained at a temperature in the range of 30 to 40° C. More preferably, the water is maintained at a temperature of about 35° C.

[0071] When the antifouling liquid is a basic solution, the pH of the basic solution may be in the range of 8 to 10. Preferably, the basic solution is a hydroxide solution such as a sodium hydroxide solution. More preferably, the concentration of the basic solution is 10 to 20% (0.25 to 1 M).

[0072] When the antifouling liquid is an acidic solution, the pH of the acidic solution may be in the range of 4 to 6. Preferably, the acidic solution may contain an edible acid such as acetic acid, citric acid, or malic acid. More preferably, the concentration of the acidic solution is 5 to 20% (0.25 to 1 M).

[0073] The cleaning protocol may include activating a valve to release an antifouling agent from a storage tank into the heat exchanger or evaporator.

[0074] The cleaning protocol may include subjecting the heat exchanger or evaporator fluid lines to ultrasonic treatment.

[0075] The cleaning protocol may include a rinse cycle to purge the antifouling agent before the cleaning protocol is terminated. The rinse cycle may purge the antifouling agent or waste products.

[0076] The method may include releasing the process fluid from the storage tank after a rinse cycle.

[0077] The present invention also provides an apparatus for concentrating a process fluid including a carrier fluid, the apparatus comprising: a heat exchanger for maintaining the process fluid at a predetermined temperature value or range of temperatures; an evaporator in fluid communication with the heat exchanger for receiving the process fluid and evaporating the carrier fluid from the process fluid to obtain a concentrate; at least one sensor for monitoring a process variable of the heat exchanger or evaporator to detect fouling in the heat exchanger or evaporator; a cleaning system for reducing fouling within the apparatus; a controller configured to receive a signal from a sensor or manual input by a user to initiate the cleaning system when a process variable falls outside a predetermined value or range; An apparatus is provided, comprising:

[0078] The apparatus may include a condenser for condensing the evaporated carrier fluid, and preferably the condenser may be in fluid communication with the heat exchanger.

[0079] The apparatus may include a conduit for recycling a portion of the evaporated carrier fluid as fluid to humidify the mass transfer fluid.

[0080] The apparatus may include one or more pressure sensors that monitor the pressure difference across the heat exchanger.

[0081] The apparatus may include a flow sensor that monitors the flow rate of the mass transfer medium through the evaporator.

[0082] The apparatus may include a flow sensor that monitors the flow rate of the process fluid through the evaporator.

[0083] The flow sensor may be a paddle flow sensor or an ultrasonic flow sensor.

[0084] The cleaning system may include one or more storage tanks containing the anti-fouling agent.

[0085] The control unit may have a manual override that allows the cleaning protocol to be initiated manually.

[0086] The controller may be configured to receive signals from the pressure sensor and / or the flow sensor to initiate a cleaning protocol for the cleaning system.

[0087] The heat exchanger may be an HVAC system. Preferably, the heat exchanger is an evaporator coil of an HVAC system.

[0088] The heat exchanger may be a cooler. Preferably, the heat exchanger is a cooler condenser.

[0089] The heat exchanger may be a counter-flow heat exchanger.

[0090] The apparatus may include at least two heat exchangers, preferably a cooler condenser and an evaporator coil.

[0091] The evaporator may be configured to directly contact the heat transfer medium with the process fluid.

[0092] The apparatus may include a recycle loop for recirculating a portion of the mass transfer medium from the evaporator.

[0093] The apparatus may include a drift chamber that receives at least a portion of the mass transfer medium from the evaporator and removes entrained process fluid to form a purified mass transfer medium stream that is returned to the evaporator, preferably via a condenser.

[0094] The drift chamber may include an eliminator to capture entrained process fluid, thereby reducing fouling of the heat exchanger.

[0095] The drift chamber may include multiple run-off outlets that return the captured process fluid to an evaporator or storage tank.

[0096] The eliminator may include a serpentine (eg, zigzag) path to facilitate capturing entrained process fluid.

[0097] The drift chamber may be configured to place the purified mass transfer medium in thermal communication with the process fluid.

[0098] The evaporator may be a spray tower configured to spray the process fluid into the flow of mass transfer medium. Preferably, the spray tower includes a spray nozzle for spraying the process fluid into the flow of mass transfer medium.

[0099] The evaporator may include a bubble plate to facilitate humidifying the mass transfer medium prior to contact with the process fluid. Preferably, the plate is made of stainless steel. More preferably, the plate has a plurality of 1 mm holes.

[0100] The evaporator may include an evaporative filler.

[0101] The apparatus may include at least one storage tank for containing the antifouling agent.

[0102] The cleaning system may include a water storage tank, an acid solution storage tank, and / or a basic solution storage tank, and may circulate one of these solutions through the heat exchanger and / or evaporator depending on the nature of the fouling material.

[0103] The apparatus may include a supply tank for containing the process fluid before it enters the heat exchanger.

[0104] The apparatus may include one or more interim sampling tanks for receiving process fluids when a cleaning protocol is initiated.

[0105] The apparatus may include an ultrasonic generator for cleaning the heat exchanger and / or evaporator, preferably attached to a conduit leading to the heat exchanger and transmitting mechanical vibrations to the fluid through the conduit. [Brief explanation of the drawings]

[0106] An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: [Figure 1] 1 is a flow diagram of an apparatus according to one aspect of the present invention. [Figure 2] FIG. 2 is a diagram of the spray tower of the device of FIG. 1. [Figure 3] FIG. 2 is a diagram of the drift chamber of the apparatus of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0107] The process fluid concentrator of the present invention is shown in FIG.

[0108] In this example, the apparatus is configured to process sugarcane extract (juice), but of course the apparatus may be configured to process other process fluids, including industrial process fluids such as wastewater.

[0109] The apparatus 10 comprises a cooler 14 including a heat exchanger in the form of a condenser 24 and a water-cooled evaporator coil 28, an evaporator in the form of a spray tower 16, a drift chamber 18, and a cleaning system comprising a first storage tank tower comprising a feed tank 12A1, a concentrate storage tank 12A2, and miscellaneous output interim sampling tanks 12A3 and 12A4, and a second storage tank tower comprising antifouling agent tanks 20B1-20B4 for individually storing a plurality of antifouling agents.

[0110] The control system includes a controller and multiple sensors, including pressure and flow sensors, that monitor process variables at various locations in the device and initiates a cleaning system if the process variables fall outside predetermined tolerance thresholds.

[0111] The extract from the sugarcane mill is stored in a supply tank 12A1, which is in fluid communication with a cooler 14.

[0112] The cooler 14 includes a water-cooled evaporator coil 28 to maintain the extract at a temperature in the range of 20-40°C until it is fed into the spray tower 16. The cooler 14 also includes a condenser 24 on the cold side of the cooler to condense water from the air stream exiting the drift chamber.

[0113] The supply tank 12A1 may be temperature controlled to maintain the extract within the predetermined temperature range. Maintaining the extract within this temperature range has been found to prevent (or at least minimize) browning of heat-sensitive extracts (e.g., 60% sucrose solutions). This avoids the need to use lime to whiten the final product. Lime is an undesirable additive because it promotes fouling in process equipment, particularly the spray tower 16, the liquid side of the chiller condenser 24, and the vapor side of the water-cooled evaporator coil 28.

[0114] The spray tower 16 is located downstream of the cooler 14. The upper portion of the spray tower includes a spray nozzle 26, which includes a process fluid inlet 30 for receiving and spraying the extract into the spray tower chamber. The lower portion of the spray tower 16 includes mass transfer medium inlets 32A, 32B for supplying air upward to meet the downwardly moving extract (see FIG. 2). This countercurrent fluid flow arrangement optimizes the mass transfer of water from the extract into the air stream, concentrating the extract.

[0115] Mass transfer medium inlet 32A is used when the evaporation step utilizes an evaporation packing, and mass transfer medium inlet 32B is used when the evaporation step involves bubbling a mass transfer medium through water.

[0116] When an evaporation packing is used, the evaporation packing is packed in region C of the spray tower in FIG.

[0117] Water is removed from the sugarcane extract in an air stream to concentrate the extract, which may be sent for further processing to produce sugars or sent to concentrate storage tank 12A2 for storage.

[0118] The spray tower 16 may include a bubble plate 34 (see FIG. 1) for humidifying the air fed into the spray tower. In this example, the air is passed through the bubble plate as bubbles, which humidify the air.

[0119] The drift chamber 18 is located between the cooler 14 and the spray tower 16 and receives at least a portion of the discharge airflow from the spray tower.

[0120] The drift chamber includes an eliminator 36 that captures unvaporized, entrained sugarcane extract droplets from the discharge airflow by directing the airflow in a serpentine (e.g., zigzag) path. The collected effluent is returned to the spray tower 16 via effluent outlets 38A-38F. Effluent outlets 38A-38E include horizontal fins 46 that direct the effluent from the drift chamber (see FIG. 3).

[0121] The purified air stream is then directed to a cooler 14 to reduce the temperature of the air stream before returning it to the spray tower. The purified air may be used as a heat transfer medium to cool a process fluid in the cooler 14.

[0122] The capture of sugar cane extract droplets from the airflow by the drift chamber minimizes fouling of the cooler condenser 24, particularly plugging of the cooler air fins by precipitated sugars from the entrained process fluid.

[0123] The apparatus 10 also includes a control system having a programmable logic controller (PLC) and a number of sensors located at various locations on the apparatus to monitor process variables including pressure, humidity, temperature, liquid level, and flow rate.

[0124] The controller receives a signal from the sensor and initiates a cleaning protocol when the pressure or flow rate falls outside a predetermined value or range, in one example, the predetermined thresholds are a pressure differential across the cooler of 10 kPa, an air flow rate through the spray tower of 15 L / min, and a process fluid flow rate through the spray tower of 0.25 L / min.

[0125] The PLC controls the treatment of process fluids, the monitoring of process variables, and the initiation of cleaning systems. The controller measures fouling buildup by detecting an increase in air or water pressure across the process equipment, or a decrease in process fluid, air, or water flow.

[0126] The cleaning protocol involves passing humidified air or an anti-fouling agent through the device by the cleaning system to remove fouling, and may be configured to occur periodically regardless of the signal from the sensor.

[0127] Pressure sensors PW1 and PW2, flow sensors VA and VB, level sensors Lx (where x indicates the fluid stream being monitored), humidity sensors HA1 and HA2, and temperature sensors TW1, TW2, TA1, and TA2 monitor various parts of the system and send signals to the PLC, which initiates cleaning protocols when the measured values ​​of certain process variables fall outside predetermined threshold ranges.

[0128] Particularly important sensors are the pressure sensors PW1 and PW2 and the flow sensors VA and VB.

[0129] Pressure sensors are located at various fluid inlets and outlets of the spray tower 16 and the cooler 14, allowing differential pressure values ​​to be calculated. Flow sensors are located in the process fluid lines, water lines, and air lines, respectively.

[0130] Pressure sensors PW1 and PW2 are positioned to monitor the pressure difference across the cooler 14. Specifically, the pressure sensors measure the pressure difference across the conduits that supply the sugar cane extract to the cooler 14. The pressure difference often increases in response to increased fouling (including, for example, the buildup of precipitated sugars).

[0131] Flow sensors VA and VB are positioned to monitor the air flow rate and sugarcane extract flow rate, respectively, of the spray tower 16. A decrease in flow rate through the spray tower often indicates an increase in fouling, which reduces the area through which fluid flows.

[0132] The second storage tank tower includes antifouling agent tanks 20B1-20B4. Tank 20B1 stores water (preferably maintained at 35°C), tank 20B2 stores an acetic acid solution, tank 20B3 stores sodium hydroxide, and tank 20B4 stores a cleaning solution (e.g., a non-toxic soap solution). When a cleaning protocol is activated, one or more cleaning agents are circulated through the cooler 14 and spray tower 16. The antifouling agent tanks may be temperature controlled to maintain the solutions at an optimum temperature. For sugar refining, the optimum temperature range for the cleaning agents is 20-40°C. Higher temperatures may be used in cases of particularly stubborn fouling.

[0133] The cleaning protocol may include sonicating the cooler 14 and spray tower 16 conduits.

[0134] The cleaning system allows the equipment to be quickly and efficiently cleaned of residual fouling caused by process fluids or other substances, such as lime.

[0135] The cleaning system also allows the equipment to handle process fluids containing fouling substances, such as lime-containing sugarcane solution, without the fouling adversely affecting the equipment's efficiency, due to the ability to monitor, reduce, and remove fouling buildup.

[0136] The first storage tank tower contains interim sampling tanks 12A3-12A4 that receive the sugarcane extract when a cleaning protocol is initiated or when a sample of the process fluid is required.

[0137] In operation, sugar cane is crushed and mixed with water to form a sugar-containing extract, which is clarified without the addition of lime and stored in feed tank 12A1 until the extract is ready for processing.

[0138] The optimum operating conditions for this example are given in the table below, which apply to the process fluid spray nozzle feed inlet conditions (and feed outlet conditions) and the air entering and leaving the spray tower.

[0139] [Table 1]

[0140] During processing, the extract is injected into a cooler 14 in the form of an HVAC (Heating, Ventilation, and Air Conditioning) system. The extract is cooled to a temperature of approximately 3-5°C, preferably 4°C, as it passes through an evaporator coil 28. This temperature range is below the maximum allowable temperature of the feed without spoiling or browning the extract in the feed. Ideally, the extract is cooled to approximately 30°C.

[0141] Alternatively, a heat exchanger with heating and cooling functions may be used instead of the cooler 14. In this embodiment, if the extract entering the heat exchanger is lower than a predetermined temperature, the extract is heated to the predetermined temperature by the heat exchanger.

[0142] The extract is then fed into the process fluid inlet 30 of the spray nozzle 26 located at the top of the spray tower 16 and sprayed downward into a humidified air stream within the chamber of the spray tower 16. The humidified air stream is formed by bubbling the air stream entering the spray tower through the mass transfer medium inlet 32A with a stream of water injected into the spray tower 16 through a stainless steel bubble plate 34 with multiple 1 mm holes.

[0143] The extract and humidified air streams meet in a countercurrent manner, removing water from the extract into the air stream and concentrating the extract. For a 250 L / day experimental system, approximately 0.17 L / min of water is evaporated from the extract. The concentrated sugar solution exits the spray tower through process fluid outlet 31, and is sent to concentrate storage tank 12A2 or directed for further processing, while the humidified air exits the spray tower through mass transfer medium outlet 33.

[0144] A portion of the humidified air 40 may be purified (cleaned) and recycled to the spray tower via the cooler 14. The air stream 40 is directed to a drift chamber inlet 42 and into the eliminator 36. Within the eliminator, entrained sugar solution removed from the humidified air stream is returned to the spray tower for reprocessing, while the purified air exits through an outlet 44 and enters the condenser 28 of the cooler 14. The purified air may be used to cool process fluids within the cooler before returning the purified air to the spray tower for reuse as a mass transfer medium.

[0145] The drift eliminator is employed specifically to reduce fouling within the condenser 24 as the airflow circulates through the cooler 14 .

[0146] In one example, the PLC initiates a cleaning protocol when the pressure across the cooler 14 exceeds 10 kPa, when the air flow rate of the spray tower 16 falls below 15 L / min, or when the process fluid flow rate of the spray tower 16 falls below 0.25 L / min.

[0147] Depending on the process variable that triggers the cleaning protocol, the PLC may take multiple steps to clean each relevant piece of equipment.

[0148] For example, if the trigger is water flow rate, the PLC controls the valves of the device to inject the process fluid from the spray tower into one or both of the temporary sampling tanks 12A3-12A4, and then cleans the spray tower water line by releasing an appropriate antifouling agent from its corresponding storage tank to circulate through the spray tower and remove fouling.

[0149] The antifouling agent is allowed to circulate through the spray tower for 10 minutes, or until the water flow rate returns to within the threshold range. Once this requirement is met, the PLC stops operation of the cleaning system and returns to passing process fluid through the device. Preferably, a water rinse cycle is performed to purge (remove) the antifouling agent from the device before the PLC returns to the process fluid.

[0150] If the trigger is air flow, the PLC controls the system's valves to inject process fluid from the spray tower into temporary sampling tanks 12A3-12A4, then cleans the spray tower air lines by circulating air through the spray tower for 10 minutes or until the air flow rate returns to within the threshold range. Once this requirement is met, the PLC stops operation of the cleaning system and returns to passing process fluid through the system. Preferably, a water rinse cycle is performed before the PLC returns to the process fluid.

[0151] In another example, the cleaning protocol included a rinse cycle (22°C wash water at 30 L / min (double cycle rate) for 10 minutes) once per day. The rinse cycle was found to reduce the fouling pressure rise in the cooler 14 from 66 kPa to 60 kPa with minimal disruption to operation (96.5% uptime).

[0152] To demonstrate the effectiveness of the cleaning system, in an exemplary process for concentrating thin (diluted) sugar juice based on both commercial raw sugar and industrial, inedible "sugar cake," water was extracted from a 145 L 12% sucrose feed stream at a rate of 120 L / day, producing 25 L of 65% sucrose concentrate without irreversibly clogging the apparatus 10. This process produced high-quality concentrated sugar and a wastewater stream. A cycle of over 30 days produced a small but significant amount of scale (several mm thick in a 25 mm pipe, enough to reduce water flow from 18 L / min to 16 L / min). A cleaning protocol using water (at various temperatures) and / or food-grade acetic acid reversed this buildup and restored flow rates to 18 L / min (to zero mm of scale within the flow measurement accuracy).

[0153] In a further example, after three consecutive days of 24-hour evaporation, the air pressure in the condenser rose from 60 psi to 66 psi. The cleaning protocol restored this pressure to 60 psi after 5-10 minutes.

Claims

1. 1. A method for concentrating a mixture containing a solvent, comprising: (a) maintaining the mixture at a predetermined temperature value or temperature range; (b) evaporating the solvent from the mixture in an evaporator to obtain a concentrated mixture and a gaseous fluid exiting the evaporator; (c) monitoring at least one parameter of step (a) or (b) selected from pressure, flow rate, temperature, humidity, and liquid level to detect contamination formed in either step (a) or (b); (d) initiating a soil removal process to reduce the soil formed when the parameter falls outside a predetermined value or range; (e) directing a portion of the gaseous fluid exiting the evaporator into a chamber downstream of the evaporator having a plurality of effluent outlets to remove the mixture carried with the gaseous fluid before returning the gaseous fluid to the evaporator; A method comprising:

2. 10. The method of claim 1, wherein step (a) comprises feeding the mixture to a heat exchanger to maintain the mixture at a predetermined temperature value or temperature range.

3. 3. The method of claim 1, wherein step (b) comprises feeding the mixture from a heat exchanger to the evaporator.

4. The method of any one of claims 1 to 3, wherein step (b) comprises heating the solvent without the use of an external heating source.

5. The method of any one of claims 1 to 4, wherein step (b) comprises directly contacting the mixture with the gaseous fluid.

6. The method of claim 5 , comprising humidifying the gaseous fluid prior to contacting the mixture.

7. 7. The method of any one of claims 1 to 6, wherein step (b) comprises spraying the mixture onto an evaporating packing and directing an airflow in a counter-current direction through the evaporating packing.

8. A method according to any preceding claim, wherein step (c) comprises monitoring the pressure difference across the heat exchanger.

9. The method of any one of claims 1 to 8, wherein step (c) comprises monitoring fluid flow rate through the evaporator.

10. 10. The method of claim 1, wherein step (d) comprises initiating the fouling treatment to reduce fouling in a heat exchanger or the evaporator when the pressure or flow rate falls outside a predetermined value or range.

11. A method according to any preceding claim, comprising recirculating a portion of the gaseous fluid discharged from the evaporator.

12. 12. The method of any one of claims 1 to 11, wherein the fouling removal treatment comprises circulating an antifouling liquid through one or more pieces of process equipment used in the method.

13. The method according to any one of claims 1 to 12, wherein the contamination removal treatment comprises subjecting a heat exchanger or a fluid line of the evaporator to ultrasonic treatment.

14. 1. A method for producing concentrated sugar from sugarcane, comprising: (a) obtaining a sugar-containing extract from sugarcane; (b) maintaining the extract at a predetermined temperature value or temperature range; (c) clarifying the extract without adding lime; (d) evaporating water from the extract in an evaporator to form concentrated sugars and an air stream exiting the evaporator; (e) monitoring a parameter of step (b) or (d) selected from pressure, flow rate, temperature, humidity, and liquid level to detect soiling formed in either step (b) or (d); (f) initiating a soil removal process to reduce the soil formed when the parameter falls outside a predetermined value or range; (g) directing a portion of the airflow exiting the evaporator into a chamber located downstream of the evaporator and having a plurality of effluent outlets to remove any unevaporated sugar cane extract droplets carried with the airflow exiting the evaporator before returning the airflow to the evaporator; A method comprising:

15. 15. The method of claim 14, wherein step (a) comprises crushing sugarcane to obtain the sugar-containing extract.

16. 16. The method of claim 14 or 15, wherein for step (b), the extract is held at a maximum temperature of 20°C to 40°C.

17. 1. An apparatus for concentrating a mixture containing a solvent, comprising: a heat exchanger for maintaining the mixture at a predetermined temperature value or temperature range; an evaporator in fluid communication with the heat exchanger for receiving the mixture and evaporating the solvent from the mixture to obtain a condensate and a gaseous fluid discharged from the evaporator; at least one sensor for monitoring a parameter selected from pressure, flow rate, temperature, humidity, and liquid level to detect fouling in the heat exchanger or the evaporator; a cleaning system for reducing contamination within the device; a controller configured to receive a signal from the sensor or from a manual input by a user to initiate the cleaning system when the parameter falls outside a predetermined value or range; a chamber located downstream of the evaporator and having a plurality of effluent outlets, the chamber receiving at least a portion of the gaseous fluid exiting the evaporator before returning the gaseous fluid to the evaporator; An apparatus comprising:

18. 20. The apparatus of claim 17, including one or more pressure sensors that monitor a pressure differential across the heat exchanger.

19. 19. Apparatus according to claim 17 or 18, including a flow sensor for monitoring the gaseous fluid flow rate or mixture flow rate through the evaporator.

20. 20. The apparatus of any one of claims 17 to 19, wherein the evaporator includes a bubble cap to facilitate humidifying the gaseous fluid before contacting the mixture.

21. 21. Apparatus according to any one of claims 17 to 20, comprising an ultrasonic generator for cleaning the heat exchanger and / or the evaporator.

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