Compact mechanical vapor recompression evaporator system
10046249 ยท 2018-08-14
Assignee
Inventors
Cpc classification
B01D1/2887
PERFORMING OPERATIONS; TRANSPORTING
International classification
Abstract
The system may include a vapor separator, a falling film evaporator, and a mechanical vapor recompression device. The system may also include a spin vane positioned at the inlet to the vapor separator. The falling film evaporator may surround an outer wall of the vapor separator, defining a common vessel.
Claims
1. A compact mechanical vapor recompression evaporator system comprising: a vapor separator comprising a cylindrical chamber defined by an outer wall; a falling film evaporator, wherein the outer wall of the cylindrical chamber forms an inner shell wall of the falling film evaporator, and wherein the outer wall of the cylindrical chamber extends to the bottom of the falling film evaporator; a mechanical vapor recompression device positioned above the vapor separator, adjacent an upper end of the falling film evaporator, in fluid communication with the vapor separator via a suction inlet positioned above a center axis of the vapor separator; and a spin vane positioned at the inlet to the vapor separator; wherein the falling film evaporator is configured to surround an outer wall of the vapor separator, defining a common vessel; wherein the mechanical vapor recompression device is configured to induce a draft and draw a vapor from within the falling film evaporator, through the spin vane, into the vapor separator, and into the mechanical vapor recompression device where the vapor is compressed, heated, and discharged horizontally into a shell of the falling film evaporator where the vapor condenses and forms a condensate.
2. The compact mechanical vapor recompression evaporator system of claim 1, wherein the common vessel has a diameter of about 14 feet or less and the compact mechanical vapor recompression system has a nominal water evaporation capacity of up to about 120,000 lbs/hr.
3. The compact mechanical vapor recompression evaporator system of claim 1, wherein the spin vane is stationary.
4. The compact mechanical vapor recompression evaporator system of claim 1, wherein the spin vane is configured such that all vapor entering the vapor separator must pass through the spin vane.
5. The compact mechanical vapor recompression evaporator system of claim 1, wherein the spin vane comprises a plurality of angled blades projecting out from an inner guide wall to an outer guide wall.
6. The compact mechanical vapor recompression evaporator system of claim 5, wherein the spin vane is configured to cause a vapor to exit the spin vane tangential to the plurality of angled blades producing a swirling of vapor within the vapor separator causing coalescing of entrained liquid droplets by direct collision of the droplets and by contact with an inner wall of the vapor separator.
7. The compact mechanical vapor recompression evaporator system of claim 6, wherein the coalescing of entrained liquid droplets increases the mass quantity of entrained liquid droplets disengaged from the vapor by falling or flowing due to gravity to the bottom of the vapor separator.
8. The compact mechanical vapor recompression evaporator system of claim 1, further including a spin reducer positioned in the vapor separator beneath the mechanical vapor recompression device, wherein a draft produced by the mechanical vapor recompression device draws a vapor from the falling film evaporator, through the spine vane, into the vapor separator, through the spin reducer, and into the mechanical vapor recompression device.
9. The compact mechanical vapor recompression evaporator system of claim 8, wherein the spin reducer is configured such that all vapor passing from the vapor separator to the mechanical vapor recompression device must pass through the spin reducer.
10. The compact mechanical vapor recompression evaporator system of claim 8, wherein the spin vane is configured to cause a swirling of vapor within the vapor separator and the spin reducer is configured to decrease the swirling of vapor before the vapor enters the mechanical vapor recompression device.
11. A compact mechanical vapor recompression evaporator system comprising: a vapor separator that defines a chamber by an outer wall and a spin vane; a falling film evaporator comprising a vertical tube and shell heat exchanger configured to surround the outer wall of the vapor separator forming a common vessel, wherein the outer wall of the cylindrical chamber forms an inner shell wall of the falling film evaporator, and wherein the outer wall of the cylindrical chamber extends to the bottom of the falling film evaporator; and a mechanical vapor recompression device located above the vapor separator, adjacent an upper end of the falling film evaporator, in fluid communication with the chamber via a suction inlet positioned above a center axis of the chamber and the shell of the vertical tube and shell heat exchanger and configured to induce a draft within the tubes of the vertical tube and shell heat exchanger through the spin vane and the chamber to the mechanical vapor recompression device; wherein the draft causes a vapor formed in the tubes of the vertical tube and shell heat exchanger as a result of evaporation to flow down through the tubes to the bottom of the vertical tube and shell heat exchanger, through the spin vane, into the chamber of the vapor separator, and into the mechanical vapor recompression device where it is compressed, increasing its temperature, and discharged horizontally into a shell of the vertical tube and shell heat exchanger to contact the outer walls of the tubes and form a condensate.
12. The compact mechanical vapor recompression evaporator system of claim 11, wherein the spin vane is configured such that all vapor entering the chamber must pass through the spin vane.
13. The compact mechanical vapor recompression evaporator system of claim 11, wherein the spin vane comprises a plurality of angled blades projecting out from an inner guide wall to an outer guide wall.
14. The compact mechanical vapor recompression evaporator system of claim 11, wherein the spin vane is configured to cause the vapor to exit the spin vane tangential to the plurality of angled blades producing a swirling of vapor within the chamber causing coalescing of entrained liquid droplets.
15. The compact mechanical vapor recompression evaporator system of claim 14, wherein the coalescing of entrained liquid droplets increases the mass quantity of entrained liquid droplets disengaged from the vapor by falling or flowing due to gravity to the bottom of the vapor separator.
16. The compact mechanical vapor recompression evaporator system of claim 11, further including a spin reducer positioned in the vapor separator beneath the mechanical vapor recompression device, wherein spin reducer is configured such that all vapor passing from the vapor separator to the mechanical vapor recompression device must pass through the spin reducer.
17. The compact mechanical vapor recompression evaporator system of claim 16, wherein the spin vane is configured to cause a swirling of vapor within the vapor separator and the spin reducer is configured to decrease the swirling of vapor before the vapor passes to the mechanical vapor recompression device.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
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DETAILED DESCRIPTION
(10) The present disclosure is described herein with reference to illustrative embodiments for a particular application. It is understood that the embodiments described herein are not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, embodiments, and substitution of equivalents that all fall within the scope of the present disclosure. Accordingly, the present disclosure is not limited by the foregoing or following descriptions.
(11) As described above, the first generation CC vapor separator was configured as a gravity separator, with the cylinder diameter of the chamber specified to achieve a vapor flow rise velocity inside the chamber at a rate sufficiently low enough to allow a portion of the entrained liquid droplets in the vapor flow to fall via gravity downward into a liquid sump. A disadvantage of the first generation design is that only a portion of the entrained liquid droplets fall via gravity downward against the flow of the vapor stream rising vertically upward through the separator vessel and thus separate from the vapor stream. The portion that fall via gravity and separate from the vapor stream are droplets of sufficient size and mass to fall via gravity against the rising vapor stream. In contrast, smaller droplets which are not of sufficient size or mass can therefore be entrained into the rising vapor stream and may be carried by the draft up through the vapor separator. Failure to separate the smaller entrained droplets diminishes the separation efficiency performance of the vapor separator and the overall performance of the evaporator system resulting in a lower quality condensate containing non-volatilized product constituents which carryover to the shell of the heat exchanger with the vapor flow. Significant entrainment of liquid droplets in the rising vapor stream can also result in mechanical damage to the mechanical vapor recompression device due to factors such as corrosion or erosion of mechanical surfaces and vibration damage to moving parts. Thus, the embodiments of the present disclosure are configured to address this limitation and improve the separation performance of the vapor separator. Furthermore, the present disclosure addresses this limitation while also decreasing the overall diameter of the vapor separator. By decreasing the overall diameter of the vapor separator, additional heat exchanger tubing may be added to increase the capacity of the evaporator system while still maintaining the overall diameter of the evaporator system to about 14 feet or less, making the system still of a suitable size to be transported over public roads.
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(13) As shown in
(14) As a result of the high ratio of total tube inside wall surface area-to-liquid mass, in combination with the turbulent flow of liquid 101 down the inside of the plurality of tubes, a high rate of thermal heat transfer into liquid 101 can be achieved. This transfer of the thermal energy increases the temperature of liquid 101 inside the tubes, promoting evaporation (e.g., flash evaporation) of volatile components in liquid 101 to a vapor 102 state, increasing the concentration of dissolved and suspended solids remaining in liquid 101.
(15) MVR device 130 can be configured to produce a draft within falling film evaporator 110 through vapor separator 120 and into the suction of MVR device 130. The draft can promote the flow of evaporated vapor 102 co-current with liquid 101 flowing vertically down the inside of the plurality of tubes. As shown in
(16) In some embodiments, falling film evaporator 110 may be operated under a partial vacuum inside the plurality of tubes enabling evaporation of the volatile components at a lower temperature as compared to atmospheric boiling temperature. Operating at lower temperature can be advantageous for applications where thermal exposure can degrade the quality of the materials in the product (e.g., aqueous food or dairy products).
(17) As shown in
(18) As shown in
(19) Vapor separator 120 can further comprise a spin vane 140, which was not present in the first generation CC design, which utilized a gravity vapor separator.
(20) As shown in
(21) Bottom cone 123 can meet outer guide wall 143 at the bottom edge, top edge, or in between. For example, the embodiment shown in
(22) As shown in
(23) As shown in
(24) Blades 141 can be releasably or fixedly coupled to inner guide wall 142 and outer guide wall 143 and be spaced evenly around the perimeter of inner guide wall 142. The number of blades 141 can range from one to many (e.g., 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, or more). As shown in
(25) Spin vane 140 as shown in
(26) The components of spin vane 140 (i.e., blades 141, inner guide wall 142, outer guide wall 143, etc.) can be fixedly couple by way of various methods (e.g., welding, fasteners, bonding, adhesive, etc.). According to other embodiments, components can be releasably coupled using various mechanisms (e.g., clips, pins, fasteners, slots, etc.). For example, inner guide wall 142 and blades 141 may be releasable from the remainder of spin vane 140 (i.e., outer guide wall 143).
(27) Easy removal of inner guide wall 142 and blades 141 may be advantageous for several reasons. For example, it may be beneficial to remove inner guide wall 142 and blades 141 during cleaning of evaporator system 100. Additionally, besides cleaning, easy removal of inner guide wall 142 and blades 141 can allow for easy swap out of these components based on application and/or operating parameters. For example, in a food, dairy or beverage application the design of blades 141 (e.g., number of blades, surface area of blades, pitch of blades, etc.) may affect the performance of vapor separator 120 and thus a specific spin vane 140 may be selected such that the vapor condensate is of a desired consistency and quality.
(28) Spin vane 140 can be configured such that vapor 102 drawn through spin vane 140 contacts blades 141. By contacting blades 141, vapor 102 can be forced to flow along the surface of blades 141 as vapor 102 can be drawn upward through spin vane 140. As a result, this can cause vapor 102 to exit spin vane 140 tangentially to the surface of blades 141. For example,
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(30) In some embodiments, droplet contact surfaces of spin vane 140 and vapor separator 120 may be designed to enable a thorough CIP cleaning in accordance with sanitary standards, including for example, 3-A standards for USDA inspected equipment used for processing of dairy products.
(31) As a result of the swirling of vapor 102 within chamber 121, as shown in
(32) In some embodiments, spin vane 140 may be configured such that the direction of spin of the vapor in vapor separator 120 may be the same direction of spin as MVR device 130. Matching the direction of spin may improve the vapor displacement performance of MVR device 130.
(33) As shown in
(34) Outer wall 151 may include a lower portion and an upper portion. The lower portion may extend parallel along outer wall 121A of chamber 121. The upper portion may extend from the upper edge of the lower portion radially outward to outer wall 121A of chamber 121. As shown in
(35) As shown in
(36) Spin reducer 150 can be configured such that the swirling vapor 102 within vapor separator 120 drawn through spin reducer 150 contacts the vertical partitions 152. By contacting partitions 152, vapor 102 can be redirected to flow vertically along the surface of partitions 152. As a result, spin reducer 150 can reduce the swirling of vapor 102 exiting vapor separator chamber 120. For example,
(37) As shown in
(38) As discussed herein, spin vane 140 can increase the ability of a vapor separator 120 of a specific diameter to accommodate a significantly greater flow of evaporated vapors while also removing a greater number of entrained liquid droplets from the vapor stream, increasing the system's evaporation capacity (i.e., nominal water evaporation rate (lbs/hr)). For example, the first generation CC system which did not have a spin vane had a nominal water evaporation capacity of up to 70,000 lbs/hr before the diameter of the system exceeded dimensions which allowed for reasonable transportation over public roads (i.e., diameter of about 14 feet or less). Now a comparable size system utilizing spin vane 140 may have a nominal water evaporation capacity of up to 120,000 lbs/hr. Thus, by incorporating spin vane 140 into evaporator system 100, the nominal water evaporation capacity can increase by up to about 70% without increasing the footprint of the system beyond the reasonable transportable limit (i.e., about 14 feet diameter).
(39) Evaporator system 100 can be manufactured of one or more metals, metal alloys, or super duplex alloys, for example, 304 stainless steel, 316 stainless steel, alloy 2205, alloy 2507, titanium, combinations thereof, and the like. The material selected can be based on the composition and concentration of the liquid product.
(40) Evaporator system 100, according to various embodiments, can comprise a plurality of instruments (e.g., temperature transmitters, pressure transmitters, mass flow meters, flow meters, conductivity probes and the like) and a plurality of valves (e.g., ball valves, butterfly valves, control valves, pressure relief valves, and the like). The plurality of instruments and valves can be used to control the flow rate, temperature, concentration, levels of the liquid and vapor products within evaporator system 100.
(41) Evaporator system 100 can further comprise a control system configured to interface with the plurality of instruments, plurality of valves, plurality of pumps and motors to operate evaporator system 100. The control system can include a computer, PLC, or the like that can be programmed to control evaporator system 100 manually, automatically, or a combination of both.
(42) In other embodiments, evaporator system 100 can further comprise additional preheaters and coolers, a feed system having tanks, additional heat exchangers, and the like equipment.
(43) According to various embodiments, evaporator system 100 can be configured to operate in various modes of operation. For example, evaporator system 100 can be operated in a steady state mode or semi-batch mode. Steady state mode can comprise evaporator system 100 continuously receiving liquid product and continuously discharging condensate and concentrate. Semi-Batch mode can comprise evaporator system 100 intermittently receiving liquid product while concentrating liquid product and continuously or intermittently discharging condensate, and then discharging all evaporator system 100 contents as concentrate once final concentration is achieved. Following discharge of all evaporator system 100 contents, the system can restart by refilling with fresh product.
(44) In some embodiments, liquid 101 can be recirculated through falling film evaporator 110 multiple times enabling liquid 101 to be concentrated to higher concentrations. For example, falling film evaporator 110 can be configured as a multi-pass evaporator, such that the discharge of the first pass is supplied to the inlet of the second pass and so forth. The multi-pass evaporator can include 2 or more passes (e.g., 3, 4, 5, 6 or more passes).
(45) Other embodiments of the present disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the present disclosure disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the present disclosure being indicated by the following claims.