JP2017094314A - Tray for distillation of high load flow rate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for stably treating a gas-liquid flow rate of a high load, by improving a cap structure on a downcomer and a tray being main internal of a distillation device.SOLUTION: A distillation treatment method and a device are provided so that a liquid flow rate is increased in a downcomer 2 by installing baffles 3, 6 and remodeling an outlet ware 4, or a pressure loss of a cap 7 is reduced by a bowl cap 7, and a gas flow rate is increased by increasing the number on a tray 1, and in addition, the cap 7 is made movable by fixing by a hollow capillary and a net, and can cope even with weaving by securing stability of operation, and a bottom part of the downcomer 2 is raised to an upper stage than a liquid height on the tray 1, and a large number of caps 7 can be installed, and a lower opening part of the downcomer 2 is also installed toward the tower wall side, and the distillation effect is improved by lengthening a distance for contacting liquid with gas, and the baffle 6 is further installed above a lower opening part of the downcomer 2, and the gas is prevented from bypassing the downcomer 2-inside in low-load and operation-starting time.SELECTED DRAWING: Figure 3

Description

Industrial application fields

The present invention relates to a distillation apparatus which is a main equipment of a chemical plant, and relates to an improved downcomer and tray which are internal parts thereof.

Distillation equipment is the main equipment for obtaining final products by refining and separating raw materials from reactants and others in chemical plants, and its performance greatly affects product quality and basic unit, so it maintains a high load while maintaining performance. Developing trays that can be processed is an economically important issue. Distillation column internals include packing (called packing) in addition to trays, and due to their low pressure loss characteristics, they have a proven track record for use in the vacuum region. In many cases, the use of trays is effective for distillation of components with a large amount of dirt and distillation in a high pressure range of normal pressure or higher, particularly 0.5 MPa or higher.

Distillation is a unit operation that separates and purifies components from a mixture by utilizing the difference in component volatility in the gas-liquid mixed fluid to be handled. The gas rising from the lower tray passes through the openings composed of holes and valves on the multiple trays that constitute the distillation apparatus, and the liquid descends from the upper tray through the downcomer associated with the tray. . The component with high volatility in the liquid flow on the tray is transferred to the gas flow by distillation that gas-liquid is mixed and brought into gas-liquid contact, and instead the component with low volatility in the gas flow is in the liquid flow. Separation and purification are carried out.

The downcomer is responsible for separating the gas from the gas-liquid mixed fluid flowing in from the tray and returning it to the upper tray (hereinafter referred to as vapor release). Therefore, it is generally necessary to ensure a wide cross-sectional area so that the liquid flow rate passing through the cross-sectional area of the downcomer becomes slow.

Another role of the downcomer is to maintain the amount of liquid (hereinafter referred to as backup) so that gas does not blow from the lower tray to the upper tray even if there is pressure fluctuation due to gas-liquid mixing on the tray. This backup height is the sum of the pressure loss equivalent of the gas passing through the tray + the equivalent of the liquid height on the tray + the equivalent of the pressure loss corresponding to the downcomer's entry and exit. There is a method of raising the bottom of the liquid downcomer above the liquid height. In that case, the liquid outflow direction from the bottom of the downcomer was in a direction directly below the bottom or away from the tower wall.

The sieve tray has a round hole as the gas rises through many openings (holes and caps) on the tray and mixes with the liquid from the downcomer, and the valve tray uses the cap. is there. In the former case, the gas rises vertically in the liquid, but in the latter case, the gas collides with the cap and rises after laterally diffusing in the liquid. Since the loss is uniformly constant and the cap is closed even at a low gas flow rate, the liquid operation is prevented, so that the operation is stable. In order to increase the amount of gas processing, it is necessary to increase the number of openings on the tray, and a device that increases the number and openings by changing the cap of about 40 mm, which has been widely used in the past, to a smaller diameter. Has been done. However, in the case of a cap, an outer frame for storing the cap and a claw to be fastened to the tray floor are required, so the occupied area per cap is required to be larger than the cap area. Also, in the case of a sheave hole or a fixed cap, the opening area is the same even if the gas load changes, so that when the rising gas pressure becomes smaller than the liquid weight, especially when the gas load decreases, liquid leakage from the opening occurs. Thus, there is a problem that mass transfer becomes insufficient (hereinafter referred to as weeping), and operation is gradually disabled due to performance degradation.

The present invention treats the downcomer even at a higher liquid load so that the distillation performance can be maintained even if the load of the gas-liquid flow rate is increased based on the above-mentioned technology known as the prior art, and on the tray surface. The improved cap handles high gas loads. Another object of the present invention is to make the pressure loss uniform by moving the bowl cap up and down according to the gas load so that it can be operated even with a low load gas.

As a means for solving the above-mentioned problems, the method according to the present invention includes a vapor release baffle installed at a downcomer with a lower end in a downercomer liquid and an upper end in a gas phase on a tray. By doing so, the entrained gas in the gas-liquid mixture that has flowed into the downcomer returns to the gas phase from between the tower wall and the baffle, and becomes a gravity flow of liquid only and can flow at a higher flow rate. It is characterized by. Further, by tilting the outlet wear to the downcomer and setting it to 45 degrees on the tray side, the downcomer inflow area increases, so that the gas accompanying the inflowing fluid can easily return to the tray.

Further, as described in claim 2, a bowl cap is installed on the tray excluding the downcomer. This is because the bottom has a spherical or elliptical shape, so there is less pressure loss when the gas flows, and there is no need for a frame or claw, so there is less dead area and more caps can be installed. It becomes possible. In addition, a hollow support thin tube is provided at the bottom of the cap so that the liquid does not stay on the inner surface of the cap. Further, the thin tube is attached to the same net together with at least one cap thin tube at the bottom of the tray, so that when the cap is moved, the net is operated in the same manner so that the cap is caught on the tray and the operation is not uneven. As a result, when the gas becomes lightly loaded, the cap moves in the hole closing direction, and it is possible to prevent weeping.

Further, as described in claim 3, by raising the bottom of the downcomer above the liquid level on the tray, a larger number of caps can be installed on the lower tray surface, and the lower opening of the downcomer is provided in the tower. Installed toward the wall side, the liquid flows out toward the wall of the tower, and the liquid comes into contact with gas to increase the flow path distance to the downcomer to the lower stage to improve the distillation effect. Furthermore, a baffle is installed above the downcomer lower opening to prevent gas from bypassing the downcomer toward the upper tray when the load is low or when the operation is started.

In the drawings, the same or substantially the same elements are denoted by the same reference numerals.

In FIG. 1, a vapor release baffle is installed in parallel with the outlet wear at a distance of 10 to 50 mm from the tower wall. The depth is 1/2 the maximum downcomer length below the tray surface, the height is 1/3 to 1/2 the interstage length, and the upper end is always a gas phase portion. The left and right sides of the baffle are in close contact with the tower, and the top and bottom are kept open so that the gas can escape well from the gas-liquid mixture.

In FIG. 1 and FIG. 3, the outlet wear is inclined by 45 degrees toward the center of the tray. The vertical height is determined in advance by chemical calculation so as to satisfy the basic performance of the tray.

In FIG. 2, at least one of the hollow support tubules is extended from the bottom center of the bowl cap cut from the bottom of the hollow hemisphere or hollow semi-elliptical sphere at a height of 1/5 to 1/3 and larger than the hole. The hollow support tubules described above are installed in a common net below the tray. Caps, capillaries and nets are generally made of metal, but any other material may be used. The hollow support capillary allows the liquid in the bowl to be drained to the lower tray when the plant is stopped.

In FIG. 3, an opening is provided so that the liquid outlet flow velocity is 1.0 m / s or less, preferably about 0.5 m / s, toward the tower wall side at the bottom of the downcomer.

In FIG. 4, a bypass cut baffle having the same length or more as the maximum distance between the opening and the tower wall and a height of ½ or more of the same length and the same width as the outlet wear is placed in the downcomer above the bottom surface thereof. Install in.

It is a schematic diagram explaining the downcomer's vapor release baffle, outlet wear and bowl caps (3 pieces) in a plurality of trays. It is a schematic diagram which shows the structure of the bowl cap (two pieces) on a tray opening part, a hollow support thin tube, and a net | network. It is the figure which cut out the inside of a tower from the side, and is a fragmentary sectional view explaining the flow of the gas-liquid which flows through the liquid outlet opening part of a downcomer bottom part, a bypass cut baffle, and a bowl cap (eight pieces). It is a fragmentary sectional view explaining the positional relationship and dimension of a bypass cut baffle.

▲ 1 ▼ Tray floor ▲ 2 ▼ Downcomer ▲ 3 ▼ Vapor release baffle ▲ 4 ▼ Outlet wear ▲ 5 ▼ Downcomer liquid outlet ▲ 6 ▼ Bypass cut baffle ▲ 7 ▼ Bowl cap ▲ 8 ▼ Net

Claims (3)

A gas-liquid separation plate (hereinafter referred to as a vapor release baffle) is vertically installed in a downcomer pipe (hereinafter referred to as a downcomer) in which liquid on a tray serving as a distillation column moves to a lower tray. In addition, a structure in which the vertical weir to the downcomer (hereinafter referred to as outlet wear) is tilted 45 degrees toward the center of the tray while maintaining the vertical height. A bowl (hereinafter referred to as a bowl cap) having a sphere or a half of an ellipse radius at the lower part of the hollow hemisphere or hollow semi-ellipse is installed in the upper part of one or more holes on the tray surface. A structure in which a hollow support thin tube is provided in the center of the cap bottom, the hollow support thin tube is passed from the hole to the back side of the tray, and fixed to a net together with the hollow support thin tube of the other cap to be movable. The bottom portion of the downcomer according to claim 1 is installed above the liquid level on the lower tray, the liquid outflow opening is directed to the tower wall, and further above the opening from the tower wall to the side of the downcomer A baffle plate (hereinafter referred to as a bypass cut baffle) with a cross-sectional area equal to or larger than the opening is installed horizontally to prevent backflow of the vapor.

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