Distillation apparatus and method for operating the distillation apparatus

Abstract

To provide a distillation apparatus that can shorten starting time.SOLUTION: There is provided a distillation apparatus 1, including: one or more packed columns D each having a regulating filling material in the column and concentrating a high-boiling point component to a liquid side and a low-boiling point component to a gas side by gas-liquid contact in the column; one or more evaporators R each vaporizing at least a part of descending liquid in the packed column and introducing a part thereof as ascending gas into the packed columns; one or more condensers C for liquefying at least a part of the ascending gas of the packed columns and introducing a part thereof into the packed columns as reflux liquid; a liquid feed path L5 located between at least one evaporator R and an upper part of at least one packed column D; one or more liquid storage containers H located in the liquid feed path; and one or more gas feed paths L7 located in a lower part of the packed columns D to which the liquid feed path L5 is connected.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a distillation apparatus and a method for operating a distillation apparatus. [Background technology]

[0002] Figure 3 is a system diagram showing an example of the configuration of a conventional distillation apparatus. As shown in Figure 3, the conventional distillation apparatus 101 includes a packed tower D containing a metal sheet-like structured packing inside the tower to increase the gas-liquid contact area, a condenser C located above the packed tower D that liquefies the gas flowing from the top of the packed tower D and returns it as reflux, and a reboiler R located below the packed tower D that gasifies the liquid at the bottom of the packed tower D and returns it as ascending gas. In the distillation apparatus 101, raw material F is supplied to the packed tower D, and high-boiling-point components are concentrated in the liquid side and low-boiling-point components are concentrated in the gas side through gas-liquid contact within the packed tower D. In the distillation apparatus 101, a portion of the liquid at the bottom of the packed tower D is extracted as product P, and a portion of the liquid liquefied by the condenser C is discharged to the outside of the system as waste liquid W1.

[0003] It is generally known that liquids with high surface tension have poor wettability with metal surfaces. For example, when distilling an aqueous solution containing a large amount of water, if a packed column D having metal sheet-like structured packing as shown in Figure 3 is used, the "Height Equivalent to a Theoretical Plate (HETP)," an index of distillation performance (performance of the packing), will be a poor value of 200 mm or more (see Non-Patent Document 1).

[0004] This is presumably because the liquid does not spread over the entire surface of the packing due to poor wettability of the liquid to the metal surface, reducing the contact area between the gas and liquid and making it difficult for distillation separation to proceed. It is known that this condition is particularly likely to occur when starting up a distillation apparatus by simply increasing the gas load in the packed column and maintaining a steady state once the operating load is reached.

[0005] Incidentally, it is known that in laboratory-scale packed columns with a column diameter of 50 mm or less that use random packing Dixon rings, which are formed by rolling mesh-like metal plates, applying a load greater than the normal operating load above the loading point during start-up causes a liquid film to form over the entire surface of the packing, resulting in good distillation performance with a HETP of 100 mm or less (see Non-Patent Document 2). Generally, when distilling liquids with high surface tension, mesh-like packing is mainly used as the structured packing, but it is also known that good distillation performance can be obtained in packed columns that use structured packing made of mesh-like metal plates by performing a similar start-up procedure.

[0006] Therefore, when starting up a distillation apparatus, the packed column is operated under overload conditions to quickly achieve "wetting of the packing material." In this case, a larger holdup (liquid volume) than usual must be created in the packed column. Therefore, in conventional distillation apparatuses, it was necessary to operate the column using more ascending gas and descending liquid than in normal operation during startup.

[0007] That is, in conventional distillation apparatuses, although they are not used in steady-state operation, it was necessary to increase the evaporation capacity of the reboiler R and the condensation capacity of the condenser C for startup. Furthermore, when liquid nitrogen or the like is used as a cooling source for the condenser C, the supply equipment system itself had to be designed to accommodate startup. Furthermore, when transitioning to steady-state operation after startup, it was necessary to enlarge the reboiler R in order to recover the cold fluid present in the packed tower. [Prior art documents] [Non-patent literature]

[0008] [Non-Patent Document 1] Hirose Eiichi, Watari Kazuo, Structured packing and low liquid load liquid distributor in systems with high surface tension, Separation Technology, Vol. 44, No. 1, pp. 38-42 [Non-patent document 2] OG Dixon, High efficiency laboratory fractionation, I. Gauze Ring Packing and Flooding Technique for Laboratory Columns, JSCL, 68, March, 1949, p. 88-91. Summary of the Invention [Problem to be solved by the invention]

[0009] As described above, in the conventional distillation apparatus and its operating method, it is necessary to temporarily apply a load to the reboiler R that is greater than the load during steady operation, which results in a larger vessel constituting the reboiler R. In other words, the vessel constituting the reboiler R is started up with an excess amount of liquid stored in it in order to spread a liquid film on the surface of the structured packing, which results in a large amount of liquid being held in the entire apparatus. This poses the problem of a long "start-up time" from the start of startup until a steady concentration distribution is formed in the packed tower.

[0010] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a distillation apparatus and an operating method thereof that can shorten the start-up time. [Means for solving the problem]

[0011] In order to solve the above problems, the present invention has the following configuration. [1] One or more packed towers having structured packings in the tower, which concentrate high-boiling components in the liquid side and low-boiling components in the gas side by gas-liquid contact in the tower; one or more evaporators for vaporizing at least a portion of the descending liquid in the packed tower and introducing the vaporized portion into the packed tower as an ascending gas; one or more condensers for liquefying at least a portion of the ascending gas in the packed tower and introducing the liquefied gas into the packed tower as reflux; a liquid supply path located between at least one of the evaporators and an upper portion of at least one of the packed towers; one or more liquid reservoirs located in the liquid supply path; and one or more gas supply lines located at the bottom of the packed tower to which the liquid supply lines are connected. [2] The distillation apparatus according to [1], further comprising a pumping device located in the liquid supply path. [3] a gas discharge path located above the packed tower, to which the liquid supply path and the gas supply path are connected; The distillation apparatus according to [1] or [2], further comprising: a gas-liquid distributor located in the gas discharge path. [4] The distillation apparatus according to [3], further comprising an exhaust device located in the gas exhaust path. [5] The distillation apparatus according to [1], further comprising a differential pressure meter for measuring the differential pressure between the top and bottom of the packed column to which the liquid supply path and the gas supply path are connected. [6] A distillation method using a distillation apparatus equipped with one or more packed towers, in which at least a portion of a liquid located at the bottom of the packed tower is vaporized by an evaporator, and a portion of the vapor is introduced into the packed tower as an ascending gas, and at least a portion of a gas located at the top of the packed tower is liquefied by a condenser, and a portion of the vapor is introduced into the packed tower as a descending liquid, When starting the distillation apparatus, In at least one of the packed towers, a part of the liquid introduced into the evaporator is supplied as a start-up liquid to an upper part of the packed tower, and a start-up gas is supplied from a lower part of the packed tower; When the distillation apparatus is operated in a steady state, For the above startup liquid A distillation method in which a portion of the liquid used as the distillation agent is discharged to the outside of the evaporator. [7] The distillation method according to [6], wherein a portion of the gas used as the start-up gas is discharged above the packed column. [8] The distillation method according to [6] or [7], wherein when the distillation apparatus is started, the distillation load in the packed column is set to be greater than the distillation load at the loading point. [9] The distillation method according to [8], wherein the state of the distillation load in the packed tower is monitored by measuring the differential pressure between the top and bottom of the packed tower. [Effects of the Invention]

[0012] The distillation apparatus and distillation method of the present invention can shorten the start-up time. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a system diagram showing an example of the configuration of a distillation apparatus according to one embodiment of the present invention. [Figure 2] FIG. 2 is a system diagram showing another example of the configuration of a distillation apparatus according to one embodiment of the present invention. [Figure 3] FIG. 1 is a system diagram showing the configuration of a conventional distillation apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0014] A distillation apparatus and a distillation method according to an embodiment of the present invention will be described in detail below with reference to the drawings. Note that the drawings used in the following description may show characteristic portions enlarged for convenience in order to make the characteristics easier to understand, and the dimensional proportions of the respective components may not necessarily be the same as those in reality.

[0015] The meanings and definitions of terms used in this specification are as follows. A numerical range expressed by "to" means that the numerical values ​​before and after "to" are the lower and upper limits of the numerical range. The upper part of the packed tower (also referred to as the upper part of the packed tower) refers to the vertical direction upward from the center of the packed tower, and the lower part of the packed tower (also referred to as the lower part of the packed tower) refers to the vertical direction downward from the center of the packed tower. The loading phenomenon occurs when, in a packed column where gas and liquid are in countercurrent contact, the liquid phase state is kept constant and the gas phase flow rate is increased, and when a certain flow rate is reached, the liquid holdup in the column begins to increase, and at the same time, the rate of increase in pressure drop also increases. The loading point is the point at which the loading phenomenon occurs. The F factor (Fs) is an index that indicates the operating load (distillation load) of a packed column. The normal operating load of a packed column is around Fs = 1.0, and a value exceeding 1 indicates a high operating load.

[0016] <Distillation apparatus> First, the configuration of a distillation apparatus according to one embodiment of the present invention will be described. Here, Fig. 1 is a system diagram showing the configuration of a distillation apparatus 1 according to one embodiment of the present invention. As shown in FIG. 1, the distillation apparatus 1 of this embodiment is generally configured to include a packed column D, a reboiler (evaporator) R, a condenser C, a spare liquid container (liquid storage container) H, and paths L1 to L11.

[0017] Packed tower D is a tower arranged with its axis oriented vertically, and high-boiling components are concentrated in the liquid side and low-boiling components in the gas side by gas-liquid contact within the tower. Here, packed tower D has structured packing inside the tower to increase the contact area between gas and liquid as described above.

[0018] The structured packing is not particularly limited and can be appropriately selected depending on the components to be distilled. When distilling a liquid with high surface tension, it is preferable to use mesh-type packing as the structured packing.

[0019] A path L1 for introducing raw material F into packed tower D is connected to the center of packed tower D. A path L2 is located at the top of the packed tower D. Here, the base end of the path L2 is connected to the top of the packed tower D, and the tip of the path L2 is connected to the upper part of the packed tower D. In addition, a condenser C is arranged in the path L2.

[0020] The condenser C is located on the path L2 and liquefies at least a part of the ascending gas flowing from the top of the packed tower D, and introduces a part of the liquefied gas as a reflux liquid into the upper part of the packed tower D. The cooling source of the condenser C can be, for example, liquefied gas or water.

[0021] Path L2 branches into path (gas discharge path) L8 at branch point a located on the primary side of capacitor C. Path L2 also branches into path L3 at branch point b located on the secondary side of capacitor C.

[0022] Path L8 is a gas discharge path located above packed tower D and branching off from path L2 at branch point a. Path L8 is equipped with, in order from the primary side, a gate valve V1, a gas-liquid separator T, and a vacuum exhaust pump (exhaust device) P1.

[0023] The gate valve V1 is a valve that blocks the flow of a fluid. It is preferable that the gate valve V1 can be adjusted to any opening from a fully closed state (0% opening) to a fully open state (100% opening). The same applies to the gate valves V2 to V6 described below.

[0024] By opening the gate valve V1 (opening degree more than 0%), at least a part of the ascending gas flowing from the top of the packed tower D via the path L2 is introduced into the path L8.

[0025] The gas-liquid separator T is located on the secondary side of the gate valve V1 in the path L8 and has the function of separating the fluid flowing through the path L8 into a liquid and a gas. The gas-liquid separator T is not particularly limited, but may be a container that has a cooling source for cooling the gas in its inner space and is capable of storing a liquid. The gas-liquid separator T is also connected to the path L9.

[0026] The path L9 is located between the gas-liquid separator T and the packed tower D. A gate valve V2 is also located on the path L9. By opening the gate valve V2, the liquid separated by the gas-liquid separator T can be returned to a position near the top of the packed tower D.

[0027] The vacuum exhaust pump P1 is located on the secondary side of the gas-liquid separator T in the path 8, and is a pump for discharging the gas separated by the gas-liquid separator T to the outside of the system as exhaust gas W2. The vacuum exhaust pump P1 is not particularly limited, but may be, for example, a rotary pump.

[0028] Path L3 is a liquid discharge path that branches off from path L2 at branch point b. A portion of the liquid liquefied by condenser C is introduced as a reflux liquid into the upper part of packed tower D via path L2, and the remainder is discharged to the outside of the system as waste liquid W1 via path L3.

[0029] A path L4 is located at the bottom of the packed tower D. Here, the base end of the path L4 is connected to the bottom of the packed tower D, and the tip of the path L4 is connected to the lower part of the packed tower D. A reboiler (evaporator) R is arranged in the path L4. In addition, the path L4 branches off from a path (product discharge path) L11 at a branch point c located on the primary side of the reboiler R.

[0030] The path L11 is a liquid extraction path that branches off from the path L4 at the branch point c. That is, the path L11 is a path for extracting, as a product P, a portion of the liquid that is extracted via the path L4 from the liquid stored in the bottom of the packed tower D.

[0031] The reboiler (evaporator) R is located on the path L4 and vaporizes at least a portion of the descending liquid flowing from the bottom of the packed tower D, and introduces a portion of the descending liquid as an ascending gas below the packed tower D. That is, the reboiler R has a container for storing the liquid and a heat source for heating the liquid. The heat source of the reboiler R can be, for example, the same type of gas as the cooling source of the condenser C, water, a heater, or the like.

[0032] To the vessel that constitutes the reboiler R, a path (liquid supply path) L5 and a path L10 are connected. Path L5 is a liquid supply path located between reboiler R and packed tower D, with its base end connected to a container that constitutes reboiler R and its tip connected to a position near the top of packed tower D. Also, on path L5, in order from the base end side (primary side), there are located gate valve V3, spare liquid container (liquid storage container) H, gate valve V5, liquid lifting pump (pressure transfer device) P2, liquid flow meter Q2, and flow control valve CV1.

[0033] The spare liquid container H is located on the downstream side of the reboiler R in the line L5, and is a container capable of storing the same substance as the liquid being distilled in the packed column D inside.

[0034] The size (volume) of the spare liquid container H is not particularly limited, and can be selected appropriately depending on the size of the distillation apparatus 1. Specifically, for example, when concentrating heavy water using a packed tower D with a packing length of 30 m and a tower diameter of 0.2 m, if the amount of holdup liquid during normal operation is about 30 L, the capacity of the spare liquid container H can be set to 50 to 100 L.

[0035] The liquid lifting pump P2 is located on the secondary side of the spare liquid container H and is a pump that lifts the liquid in the containers that make up the reboiler R and the spare liquid container H to a position near the top of the packed tower D. The liquid lifting pump P2 is not particularly limited, but for example, a magnetic pump can be used.

[0036] The liquid flow meter Q2 is located on the secondary side of the liquid lifting pump P2 and measures the flow rate of the liquid flowing through the path L5. The liquid flow meter Q2 is not particularly limited, but may be, for example, a thermal conduction type.

[0037] The flow control valve CV1 is located on the secondary side of the liquid flow meter Q2 and is a valve that adjusts its opening continuously or in stages from fully closed (0%) to fully open (100%) depending on the flow rate. The same applies to the flow control valve CV2.

[0038] According to the distillation apparatus 1 of this embodiment, by opening the gate valve V3 of the path L5 and closing the gate valve V5, a portion of the liquid in the container that constitutes the reboiler R can be stored in the spare liquid container H.

[0039] Furthermore, according to the distillation apparatus 1 of this embodiment, by opening the gate valves V3 and V5 of the path L5, at least a portion of the liquid stored in the container constituting the reboiler R and the spare liquid container H can be pumped from the bottom side of the packed tower D to a position near the top side by the liquid pumping pump 2, and introduced into the packed tower D at a required flow rate by the liquid flow meter Q2 and the flow control valve CV2 to a position near the top side.

[0040] Path L5 merges with path L10 at a junction d located between gate valve V5 and liquid pump P2, and branches off into path L6 at a branch point e located between liquid pump P2 and liquid flow meter Q2.

[0041] Path L6 is a liquid discharge path that branches off from path L5 at branch point e. Path L6 is also provided with a gate valve V6. By opening gate valve V6, a portion of the liquid flowing through path L5 is discharged to the outside of the system via path L6 as waste liquid W3.

[0042] The path L10 is a liquid supply path located between the reboiler R and the junction d of the path L5, and has a base end connected to a container constituting the reboiler R and a tip end connected to the junction d of the path L5. A gate valve V4 is also disposed in the path L10.

[0043] According to the distillation apparatus 1 of this embodiment, by opening the gate valve V4, a portion of the liquid in the containers constituting the reboiler R can be supplied to the liquid lifting pump P2 without passing through the spare liquid container H. In other words, the path L10 is a bypass path that bypasses the spare liquid container H.

[0044] A path (gas supply path) L7 for introducing the ascending gas G into the packed tower D is connected to the bottom of the packed tower D. In addition, a gas flow meter Q3 and a flow control valve CV2 are located in this order from the primary side on the path L7.

[0045] The gas flow meter Q3 measures the flow rate of the gas flowing through the path L7. The gas flow meter Q3 is not particularly limited, but may be, for example, a differential pressure type.

[0046] The distillation apparatus 1 of this embodiment includes the path L7, the gas flow meter Q3, and the flow control valve CV2, and therefore the ascending gas G, whose flow rate is controlled to a required value, can be introduced into the packed tower D from the lower part of the packed tower D (i.e., a position near the top of the tower).

[0047] The distillation apparatus 1 of this embodiment is provided with a differential pressure gauge Q1 that measures the differential pressure between the top and bottom of the packed tower D.

[0048] <Distillation method> Next, the configuration of a distillation method according to one embodiment of the present invention will be described using the above-described distillation apparatus 1 as an example. The distillation method of this embodiment uses a distillation apparatus 1 equipped with a packed packed tower D, in which at least a portion of the liquid located at the bottom of the packed tower is vaporized by a reboiler (evaporator) R and introduced into the packed tower D as an ascending gas, and at least a portion of the gas located at the top of the packed tower D is liquefied by a condenser (condenser) C and introduced into the packed tower D as a descending liquid.When starting up the distillation apparatus 1, a portion of the liquid introduced into the reboiler R is supplied to the top of the packed tower D as a start-up liquid, and the ascending gas G is supplied from the bottom of the packed tower D as a start-up gas.When the distillation apparatus 1 is in steady-state operation, a portion of the liquid used as the start-up fluid is led out of the reboiler R and stored in a spare liquid container H. Hereinafter, the start-up method for starting the distillation apparatus 1 and the operating method for steady-state operation of the distillation apparatus 1 will be specifically described, taking as an example the case of concentrating deuterium by distilling pure water.

[0049] (How to start up a distillation apparatus) In the distillation method of this embodiment, when the distillation apparatus 1 is started up, an operation is performed to intentionally maintain a high load operating state of the packed tower D by the methods shown in Step 1 and Step 2 below.

[0050] "Step 1" First, the heat load of the packed tower D is increased above that during steady operation (i.e., the output of the reboiler R is increased), and the aperture of the flow control valve CV1 located on the line L5 connected near the top of the packed tower D is adjusted to inject a liquid having approximately the same composition as the substance to be distilled (water when concentrating deuterium by distilling pure water) into the packed tower D at a flow rate adjusted to the flow rate when all the gas with an Fs of 1.5 or more is liquefied. This liquid is supplied from a container constituting the reboiler R installed in the packed tower D or from a spare liquid container H using the line L5 and the liquid lifting pump P2 with the gate valves V3 to V5 open.

[0051] "Step 2" Next, the opening of flow control valve CV2 located on line L7 connected near the bottom of packed tower D is adjusted to introduce ascending gas G into packed tower D as start-up gas. Ascending gas G can be a gasified process fluid (water vapor when concentrating deuterium by distilling pure water) or an inert gas with a boiling point lower than that of water, such as nitrogen or argon. The flow rate of ascending gas G is adjusted to 1.5 or more in terms of Fs before injection. The introduced ascending gas G is exhausted as exhaust gas W2 by vacuum exhaust pump P1 through line L8, which branches off from line L2 connecting the top of packed tower D and condenser C. When part of the ascending gas G is exhausted, it passes through gas-liquid separator T, and the liquid component is recovered in packed tower D via line L9.

[0052] In the distillation method of this embodiment, when the distillation apparatus 1 is started, the operating load (distillation load) in the packed column D is set to be larger than the operating load (distillation load) at the loading point. Whether the operating load (distillation load) in the packed tower D has reached the loading point or above can be confirmed by using the differential pressure gauge Q1 to measure the differential pressure between the top and bottom of the packed tower D. In other words, the state of the operating load (distillation load) in the packed tower D can be monitored using the differential pressure gauge Q1.

[0053] The value of the differential pressure gauge Q1 varies depending on the type of packing in the packed tower D. Specifically, when concentrating deuterium by distilling pure water, it is determined that the loading point has been reached when the value of the differential pressure gauge Q1 reaches 1 kPa / m or more.

[0054] Next, after the operating load (distillation load) in packed tower D reaches or exceeds the loading point, steps 1 and 2 are maintained until a sufficient time has passed (two hours or more in the case of concentrating deuterium by distillation of pure water) for a liquid film to form on the packing in packed tower D. This improves the distillation performance of packed tower D.

[0055] (Transition to normal operation) In the distillation method of this embodiment, after the start-up operation of the distillation apparatus 1 is completed, an operation is performed to return to a steady operating state, that is, a normal operating load (distillation load; Fs = approximately 1.0). Specifically, when the heat load of the reboiler R is reduced to the normal operating load after the start-up operation is completed, most of the liquid that has spread over the packing in the packed tower D returns to the container that makes up the reboiler R, so that the amount of liquid necessary for distillation remains in the container of the reboiler R, and the excess liquid is recovered in the spare liquid container H.

[0056] In the conventional operation method of a distillation apparatus, it was necessary to charge a liquid amount into the reboiler R vessel at the time of starting the apparatus that was at least twice the holdup (about 3% of the packed column volume) during normal operation. Furthermore, in the conventional operation method of the distillation apparatus, when starting up the apparatus, it was necessary to apply a load to the reboiler R that was 1.5 times or more the normal operating load (1.5 or more in terms of Fs) to increase the amount of ascending gas.

[0057] In contrast, the distillation method of the present embodiment can significantly reduce the amount of liquid retained during the preparation process, thereby shortening the start-up time. Furthermore, in the distillation method of this embodiment, the required heat load of the reboiler R can be reduced to 70% or less when the apparatus is started up.

[0058] As described above, according to the distillation apparatus 1 and distillation method (start-up method) of this embodiment, the amount of liquid held in the reboiler R can be reduced, and the start-up time can be shortened.

[0059] Specifically, for example, when concentrating heavy water using a packed tower with a packing length of 30 m and a tower diameter of 0.2 m, the amount of liquid held can be reduced by about 30 L, making it possible to shorten the start-up time by about two weeks. The required heat load of the reboiler R can be reduced, which reduces equipment costs.

[0060] In addition, when concentrating heavy water using a packed tower with a packing length of 30 m and a tower diameter of 0.2 m, the heat load during normal operation is 22.5 kW and the heat load during startup operation is 50 kW, making it possible to reduce the heat load by approximately 27.5 kW.

[0061] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0062] In the present invention, it is preferable to design the evaporation capacity of the reboiler R and the condensation capacity of the condenser C assuming steady operation. In the present invention, when the operating pressure in the packed tower D is lower than atmospheric pressure, the fluid in the packed tower D may be sucked by the vacuum exhaust pump P1.

[0063] Furthermore, in the distillation apparatus 1 of the above-described embodiment, the reboiler R and the spare liquid container H are separated by the gate valve V3 as an example, but the present invention is not limited to this. The reboiler R and the spare liquid container H may be directly connected by a path L5 without the gate valve V3.

[0064] In the above-described embodiment, the distillation apparatus 1 is described as having one packed tower D, but the present invention is not limited to this. The present invention can also be implemented in a case where the number of packed towers is two or more, and each packed tower is provided with a path (liquid supply path) L5 located between the container constituting the reboiler R and the packed tower, and a path (gas supply path) L7 connected near the bottom of the packed tower.

[0065] In this case, the ascending gas G may be supplied to each packed tower simultaneously. Furthermore, the liquid supply path L5 and the gas supply path L7 may be shared by multiple packed towers, and the liquid fluid may be supplied to each packed tower simultaneously. In other words, each packed tower may be started simultaneously.

[0066] Alternatively, each packed tower may be started partially. In this case, part of the ascending gas G in the packed tower that has already started may be supplied as the ascending gas G to the packed tower to be started. Also, the liquid fluid recovered in the spare liquid container H from the packed tower that has already started may be supplied to the packed tower to be started.

[0067] Figure 2 is a system diagram showing another example of a distillation apparatus according to one embodiment of the present invention. As shown in Figure 2, distillation apparatus 21 differs in configuration from distillation apparatus 1 shown in Figure 1 in that it includes packed towers D1 to D3 connected in series instead of packed tower D, paths 51 to 53 instead of path 5, and paths 71 to 73 instead of path 7. The other components of distillation apparatus 21 are the same as those of distillation apparatus 1, and therefore the same reference numerals are used and their description will be omitted.

[0068] As shown in FIG. 2, a path L2 and a path L9 are connected to the upper part of the packed tower D1. A path L1 for introducing raw material F into packed tower D1 is connected to the center of packed tower D1.

[0069] Between the packed tower D1 and the packed tower D2, a path L12 and a path L21 are located. The base end of the path L12 is connected to the bottom of the packed tower D1, and the tip end is connected to the top of the packed tower D2, so that the path L12 can supply a portion of the liquid stored at the bottom of the packed tower D1 as a descending liquid to a position near the top of the packed tower D2. The base end of the path L21 is connected to the top of the packed tower D2, and the tip end is connected to a position near the bottom of the packed tower D1, so that the path L21 can supply a part of the gas stored at the top of the packed tower D2 as an ascending gas to a position near the bottom of the packed tower D1.

[0070] Between the packed tower D2 and the packed tower D3, the path L23 and the path L32 are located. The base end of the path L23 is connected to the bottom of the packed tower D2, and the tip end is connected to the top side of the packed tower D3, so that the path L23 can supply a portion of the liquid stored at the bottom of the packed tower D2 as a descending liquid to a position near the top side of the packed tower D3. The base end of the path L32 is connected to the top of the packed tower D3, and the tip end is connected to a position near the bottom of the packed tower D2, so that the path L32 can supply a part of the gas stored at the top of the packed tower D3 as an ascending gas to a position near the bottom of the packed tower D2.

[0071] A path L4 is connected to the bottom of the packed tower D3. In addition, a branch point c and a reboiler R are located on the path L4.

[0072] Paths (gas supply paths) L71-73 are connected to the bottom of the packed towers D1-D3, respectively, for introducing the ascending gas G into the packed towers D1-D3. Gas flow meters Q3-1-3-3 and flow control valves CV2-1-2-3 are located on the paths L71-73, in this order from the primary side.

[0073] A path (liquid supply path) L51 is connected to the reboiler R. The path L51 branches into a path L53 at a branch point f and into a path L52 at a branch point g.

[0074] Paths (liquid supply paths) L51-53 are connected to the tops of the packed towers D1-D3, respectively, for introducing a portion of the liquid stored in the reboiler R or the spare liquid container H into the packed towers D1-D3 as descending liquid. In addition, liquid flow meters Q2-1-2-3 and flow control valves CV1-1-1-3 are located on the paths L51-53, in order from the primary side.

[0075] As shown in FIG. 2, in the case of a distillation apparatus 21 comprising three packed towers D1 to D3, the packed towers D1 to D3 may be started simultaneously, or any part of the towers may be started sequentially.

[0076] 2, the distillation apparatus 21 has been described as an example in which the liquid stored at the bottom of packed tower D3 is introduced into spare liquid container H via path L51, but this is not limiting. For example, the distillation apparatus 21 may be configured such that the liquid stored at the bottom of one or both of packed towers D1 and D2 is introduced into spare liquid container H via a path not shown.

[0077] In addition, in the distillation apparatus 21 shown in FIG. 2, a configuration in which the vacuum exhaust pump P1 is connected only to the packed tower D1 has been described as an example, but it may also be configured to be connected to the top of one or both of the packed towers D1 and D2.

[0078] Furthermore, while the distillation apparatuses 1 and 21 in the above-described embodiments have been described as examples in which deuterium is concentrated by distilling pure water, the present invention is not limited to this. For example, the present invention may be applied to an apparatus and method for separating oxygen isotopes by using oxygen gas as the raw material F and successively using multiple packed columns. Furthermore, the present invention may be applied to the distillation of an aqueous solution containing a hydrocarbon substance with a low concentration of the target component. [Example]

[0079] The effects of the present invention will be explained below using examples, but the present invention is not limited to the configurations of the examples.

[0080] <Example> In a distillation apparatus 1 equipped with a packed column D having a packed length of 30 m and a column diameter of 0.2 m and containing metallic mesh-like structured packing, as shown in Figure 1, pure water, a substance with a high surface tension, was distilled and deuterium was concentrated. When starting up the distillation unit, the following methods (1) and (2) were used to intentionally maintain a high operating load. After improving the distillation performance, the unit was returned to a normal operating load (Fs = approximately 1.0).

[0081] (1) A liquid (water) with approximately the same composition as the substance to be distilled was injected into the packed tower D via a flow control valve CV1 located near the top of the packed tower D, and the flow rate was adjusted to the amount required for liquefying all of the gas with an Fs of 1.5 or more. This liquid was supplied from the reboiler R or spare liquid container H attached to the packed tower D using a lifting pump P2. Reboiler R and spare liquid container H were equipped with gate valves V3 to V5 to allow liquid to be added and removed. After the start-up operation was completed, the heat load of reboiler R was reduced to the normal operating load, and most of the liquid that had spread over the packing in packed tower D returned to reboiler R. Only the amount of liquid necessary for distillation was retained, and the remainder was recovered in spare liquid container H.

[0082] (2) Rising gas G was injected into packed tower D through flow control valve CV2 located near the bottom of packed tower D. The rising gas G used here was a gasified process fluid (steam). The rising gas G was injected at a flow rate of 1.5 or more in terms of Fs. The injected ascending gas G was exhausted by the built-in vacuum exhaust pump P1. During the exhaust, the liquid component was recovered in the packed tower D by passing it through a gas-liquid separator T.

[0083] Whether the loading point or above was reached due to high load operation was determined from the value of the differential pressure gauge Q1 installed in the packed tower D. When the differential pressure value of the differential pressure gauge Q1 reached 1 kPa / m or more, (1) and (2) were maintained for at least two hours, and then operations were carried out to return to normal operating conditions (i.e., operations to reduce the heat load of the reboiler R to the normal operating load, or operations to stop the injection of liquid and the injection of the ascending gas G). The total time required for this operation was approximately 3 hours.

[0084] <Comparative Example> In a distillation apparatus 101 equipped with a packed column D having a packed length of 30 m and a column diameter of 0.2 m and containing metallic mesh-like structured packing, as shown in Figure 3, pure water, a substance with a high surface tension, was distilled and deuterium was concentrated.

[0085] When starting up the distillation unit, the heat load of the reboiler R was gradually increased to a load 1.5 times or more the normal operating load (1.5 or more in terms of Fs), and after maintaining this state for more than two hours, the load was returned to the normal operating load (Fs = around 1.0). The total time required for this operation was approximately 3 hours.

[0086] In the start-up method of the comparative example, in addition to the minimum amount of liquid required for the reboiler R during normal operation, it was necessary to charge into the container constituting the reboiler R an amount of liquid (60 L or more) that was more than twice the holdup during normal operation (approximately 3% of the packed tower volume). In contrast, in the Example, only the minimum amount of liquid required for the reboiler R during normal operation was required, so the amount of liquid held during normal operation could be reduced by 60 L or more compared to the Comparative Example. This reduction in the amount of held liquid reduced the start-up time required to reach the product concentration by more than one month.

[0087] Furthermore, in the comparative example, it was necessary to apply a load of 1.5 times or more the operating load (1.5 or more in terms of Fs) to the reboiler R to increase the amount of ascending gas, but in the present invention, the required heat load of the reboiler R could be reduced to 70% or less of that in the comparative example. [Explanation of symbols]

[0088] 1, 21 Distillation apparatus C Condenser CV1 flow control valve CV2 flow control valve D Packed tower D1 Packed tower D2 packed tower D3 Packed tower H Spare liquid container (liquid storage container) L1~L11, L12~L73 routes P1 Vacuum exhaust pump (exhaust device) P2 Lifting pump (pressure transfer device) Q1 Differential pressure gauge Q2 Liquid flow meter Q3 Gas Flow Meter R Reboiler (evaporator) T Gas-liquid separator V1~V6 gate valves

Claims

1. one or more packed towers having structured packing therein, wherein high boiling point components are concentrated in the liquid side and low boiling point components are concentrated in the gas side by gas-liquid contact in the tower; one or more evaporators for vaporizing at least a portion of the descending liquid in the packed tower and introducing the vaporized portion into the packed tower as an ascending gas; one or more condensers for liquefying at least a portion of the gas rising in the packed tower and introducing the liquefied gas into the packed tower as reflux; a liquid supply path located between at least one of the evaporators and an upper portion of at least one of the packed towers; one or more liquid reservoirs located in the liquid supply path; and one or more gas supply lines located at a lower portion of the packed column to which the liquid supply lines are connected.

2. The distillation apparatus of claim 1 , further comprising a pumping device located in the liquid supply path.

3. a gas discharge path located above the packed tower, to which the liquid supply path and the gas supply path are connected; The distillation apparatus according to claim 1 or 2, further comprising: a gas-liquid distributor located in the gas discharge path.

4. The distillation apparatus according to claim 3 , further comprising an exhaust device located in the gas exhaust path.

5. 2. The distillation apparatus according to claim 1, further comprising a differential pressure meter for measuring a differential pressure between an upper portion and a lower portion of the packed column to which the liquid supply line and the gas supply line are connected.

6. A distillation method using a distillation apparatus equipped with one or more packed towers, the method comprising the steps of: vaporizing at least a portion of a liquid located in a lower portion of a packed tower using an evaporator, introducing the vaporized portion into the packed tower as an ascending gas; liquefying at least a portion of a gas located in an upper portion of the packed tower using a condenser, and introducing the liquefied portion into the packed tower as a descending liquid; When starting the distillation apparatus, In at least one of the packed towers, a part of the liquid introduced into the evaporator is supplied to an upper part of the packed tower as a start-up liquid, and a start-up gas is supplied from a lower part of the packed tower; When the distillation apparatus is operated in a steady state, A distillation method in which a portion of the liquid used as the starting liquid is led out of the evaporator.

7. 7. The distillation method according to claim 6, wherein a portion of the gas used as the starting gas is discharged to the top of the packed column.

8. The distillation method according to claim 6 or 7, wherein when the distillation apparatus is started, the distillation load in the packed column is set to be greater than the distillation load at the loading point.

9. The distillation method according to claim 8, wherein the state of the distillation load in the packed tower is monitored by measuring the differential pressure between the top and bottom of the packed tower.

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