CN201344751Y - Spiral-plate heat exchanger used for separating silane and ammonia in silane production - Google Patents

Abstract

The utility model discloses a spiral-plate heat exchanger used for separating silane and ammonia in silane production, comprising a tank and a spiral plate; the spiral plate is formed by two metal plates, which are welded on a separation baffle and whirled into a spiral shape; the two metal plates form two spiral paths; the spiral plate is arranged in the middle section of the tank; the top and bottom of one spiral path are sealed; the bottom of the spiral path spiral centre is connected with a coolant inlet tube which extends to the outside of the tank; the upper end of the outer margin of the spiral path is connected with a coolant outlet tube, which is extends to the outside of the tank; the top and bottom of the other spiral path are opened and are communicated with each other; a gas mixture inlet tube is arranged at the bottom of the tank, and a silane gas outlet tube is arranged on the upper part of the tank. The utility model overcomes the defects that the existing spiral-plate heat exchanger can not be used for separating silane and ammonia in silane production by magnesium silicide method; not only the advantage of efficient heat exchange of the spiral-plate heat exchanger is fully used, but also the gravity is used for separating the liquid ammonia and gaseous silane.

Description

Spiral plate heat exchanger for the separation of silane and ammonia in silane production

technical field

The utility model relates to a spiral plate heat exchanger used for the separation of silane and ammonia in the production of silane by the magnesium silicide method.

technical background

There are many methods for silane production, such as UCC non-homogenization method, alloy method, halide reduction method, etc. Wherein the magnesium silicide method is a kind of silane production method, adopts liquid ammonia as reaction medium reaction equation is as follows:

A large amount of ammonia coexisting with silane must be separated first, and then the crude silane is purified by liquid nitrogen temperature rectification or molecular sieve adsorption. The low-temperature separation technology used for the separation of silane and ammonia, the heat exchanger used in the low-temperature separation is a shell-and-tube heat exchanger, which is characterized by easy cleaning, the flow direction of gas and liquid in it is straight up and down, and the gas-liquid separation is simple and easy The disadvantage is that the heat exchange time of the material is short, the heat exchange efficiency is low, and the large volume of material cannot be passed through, which may easily cause the heat exchange to be incomplete and the ammonia gas will be brought into the next purification process. The gas flow rate during the separation of silane and ammonia cannot be large, which seriously restricts the output of silane.

Introduction of existing spiral plate and shell and tube heat exchangers:

Tube and tube heat exchanger is the most widely used heat exchanger in chemical production. It is mainly composed of shell, tube, head, flange, etc. (see Figure 1). The required materials can be made of ordinary carbon steel, red copper, or stainless steel. During heat exchange, one kind of fluid enters from the connecting pipe of the head, flows in the pipe, and flows out from the outlet pipe at the other end of the head, which is called the tube side; The other connection on the shell flows out, which is called the shell side.

In the process of producing silane by the magnesium silicide method, in order to separate ammonia and silane, a low-temperature condensation separation method is used, and the condenser uses a shell and tube type. Because at low temperature conditions, due to the different liquefaction temperatures of silane and ammonia (boiling point of silane -111.5°C, ammonia -34.5°C), low-temperature condensation is used to separate the liquefaction of ammonia from silane. In addition to the function of heat, it is also necessary to separate ammonia from silane, that is to say, heat exchange is not the purpose, but the separation of ammonia and silane is the purpose. Using the tube side of the single-tube tube-and-tube condenser, the silane mixture gas is used in the tube side, and the condensing medium is used in the shell layer. Silane and ammonia gas exchange heat with the condensing medium in the tube side. After the ammonia gas is liquefied, it flows down the tube wall. The upper port of the condenser tube flows out, so as to achieve the purpose of separating ammonia and silane. That is to say, the tube side of the tube-and-tube condenser is a straight-through structural feature. When the tube side of the tube side is in a vertical state, the liquid flows downward along the tube wall under the action of the earth's gravity, so that After condensation and heat exchange, the ammonia becomes liquid, while the silane is still in the gaseous state, so that the ammonia and silane can be separated. This is a process for the separation of ammonia and silane used in the production of silane by the magnesium silicide method.

The existing spiral plate heat exchanger is a kind of high-efficiency heat exchange equipment. The medium flows in full countercurrent in the heat exchanger, and the two media can obtain the same flow characteristics. Usually used for steam condensation, liquid evaporation heat transfer. As shown in Figures 2 and 3, the structural characteristics of the existing spiral plate heat exchanger: it is made of two metal plates welded on a partition baffle and rolled into a spiral shape, and the two metal plates form two strips in the device. Spiral channel, with cover plates or heads welded on the top and bottom respectively (see Figure 2). Its characteristics: ①The heat transfer coefficient is large, and a higher flow rate can be selected (20m/s for liquid 2m/s gas). The fluid allows a higher flow rate in the spiral plate, and the fluid flows along the spiral direction, and the stagnant layer is thin. Therefore, the heat transfer coefficient is large and the heat transfer efficiency is high. The heat transfer coefficient is about twice that of the tube-and-tube heat exchanger, and the heat transfer efficiency is three times that of the tube-and-tube heat exchanger. In addition, due to the high flow rate, dirt is not easy to stay. ②Recoverable low-temperature heat energy. ③The heat loss is small. The outer surface area is small, and the fluid close to normal temperature flows out (in) from the edge channel, and heat preservation is not required. ④ Self-cleaning dirt. The medium goes through a single channel, which allows a higher flow rate than other heat exchangers. Due to the high flow rate of the fluid, the suspended solids in the fluid are not easy to settle down. ⑤Compact structure. The heat transfer area per unit volume is about three times that of the shell and tube heat exchanger. For example, a spiral plate heat exchanger with a heat transfer area of about ^100m2 has a diameter and height of only about 1.3m and 1.4m, and its volume It is only a fraction of the shell and tube heat exchanger. ⑥ low price. The equipment cost of the spiral plate heat exchanger required by the same process is only 1/2 to 1/3 of that of the spiral plate heat exchanger.

Although the existing spiral plate heat exchanger has many advantages compared with the shell and tube heat exchanger, the characteristic of silane production by magnesium silicide method is that the separation of silane and ammonia is required, and heat exchange is not the purpose. The structural feature of the spiral plate heat exchanger is two spiral channels, and the two media flow countercurrently. For the method of separating liquid ammonia and gaseous silane by gravity, it is obvious that the existing spiral plate heat exchanger cannot do it.

Contents of the invention

The technical problem to be solved by the utility model is to improve the structure of the existing spiral plate heat exchanger, and provide a spiral plate heat exchanger for the separation of silane and ammonia in the production of silane, so as to realize the production of silane in the magnesium silicide method A spiral plate heat exchanger is used for the separation of silane and ammonia.

The basic idea is: use the condensing medium to go through one of the spiral channels, and the upper and lower ends of the other channel are not closed, but its inlet and outlet are closed, so that ammonia and silane enter from the lower part of the spiral plate heat exchanger, and go through the upper and lower openings. The axial direction of the spiral plate flows from bottom to top and flows out from the upper part of the heat exchanger. In this way, the flow direction of the mixed gas of ammonia and silane is not the helical flow, but flows from bottom to top between the unwelded plate seams of the spiral plate for heat exchange. After heat exchange, the ammonia gas is converted into a liquid state, flows down from the upper part of the spiral plate along the plate wall, and gaseous silane flows out from the upper outlet.

The utility model is a spiral plate heat exchanger used for the separation of silane and ammonia in silane production, including a tank body and a spiral plate; the spiral plate is formed by welding two metal plates on a partition baffle and coiling them into a spiral shape. Two metal plates form two spiral passages; the spiral plate is placed in the middle of the tank body; its characteristic is that the top and bottom of one spiral passage are sealed, and the bottom end of the spiral center of the spiral passage is connected to the refrigerant inlet pipe, carrying The refrigerant inlet pipe passes through the outside of the tank, the outer edge of the spiral channel is connected to the refrigerant outlet pipe, and the refrigerant outlet pipe passes through the tank body; the top and bottom of the other spiral channel are open and penetrate up and down; the bottom of the tank body is equipped with The mixed gas enters the pipe (which is also the outlet of liquid ammonia), and the upper part of the tank body is provided with a silane gas exit pipe.

The utility model overcomes the defect that the existing spiral plate heat exchanger cannot be used for the separation of silane and ammonia in the production of silane by the magnesium silicide method, and not only makes full use of the high-efficiency heat exchange characteristics of the spiral plate heat The purpose of gravity to separate liquid ammonia from gaseous silane.

Description of drawings

Fig. 1 is a schematic structural diagram of an existing tube-and-tube heat exchanger;

Fig. 2 is a structural schematic diagram of an existing spiral plate heat exchanger;

Fig. 3 is a structural schematic diagram (top view) of the spiral plate of the existing spiral plate heat exchanger;

Fig. 4 is the structural representation of the spiral plate heat exchanger used for the separation of silane and ammonia in the production of silane according to the utility model;

Fig. 5 is a schematic view of the spiral plate structure (overlooking) of the spiral plate heat exchanger used for the separation of silane and ammonia in the production of silane according to the present invention.

Detailed ways

Below in conjunction with accompanying drawing and embodiment, the utility model is described in further detail.

As shown in Figures 4 and 5, the spiral plate heat exchanger used for the separation of silane and ammonia in silane production includes a tank body 1 and a spiral plate 2; the spiral plate is welded on a partition baffle 3 by two metal plates and Rolled into a spiral shape, two metal plates form two spiral channels; the spiral plate is placed in the middle of the tank body; among them, the top and bottom of a spiral channel 10 are respectively welded with a cover plate or a head 4, the spiral channel The bottom end of the spiral center is connected with the refrigerant inlet pipe 5, and the refrigerant inlet pipe passes through the outside of the tank, and the outer edge of the spiral passage is connected with the refrigerant outlet pipe 6, and the refrigerant outlet pipe passes through the outside of the tank; The top and bottom are openings 7, which are connected up and down; the bottom of the tank is provided with a mixed gas inlet pipe 8 (also an outlet for liquid ammonia), and the upper part of the tank is provided with a silane gas outlet pipe 9. When actually preparing the device, it is only necessary to remove the top and bottom cover plates or caps 4 of one spiral channel of the prior art to make it open.

In the production of silane by the magnesium silicide method, the brine (condensing medium) is adopted to go through the spiral channel 10. Since the upper and lower ends of the spiral channel 11 are not closed (if it is modified from an existing spiral plate, its inlet pipe and outlet pipe are closed), Let the mixed gas of ammonia and silane enter from the lower part of the spiral plate heat exchanger, follow the axial direction of the spiral channel 11, flow from bottom to top, and flow out from the upper part of the heat exchanger. In this way, the flow direction of the mixed gas of ammonia and silane is not the helical flow, but flows from bottom to top between the unwelded plate seams of the spiral plate for heat exchange. After heat exchange, the ammonia gas is converted into a liquid state, flows down from the upper part of the spiral plate along the plate wall, and gaseous silane flows out from the upper outlet.

Two spiral plate heat exchangers can be connected in series to form a secondary heat exchange. The heat exchange efficiency is higher and more thorough. In the case of other equipment and inconvenient processes, it can make the separation of silane and ammonia more thorough, and can improve the efficiency of silane. output.

Claims (1)

1, a kind ofly is used for the spiral-plate heat exchanger that production of silane silane separates with ammonia, comprises tank body (1) and spiral plate (2); Spiral plate is welded on a separation baffles (3) by two metallic plates and goes up and be rolled into that screw type forms, and two metallic plates constitute two helical ducts; Spiral plate places the tank body stage casing; It is characterized in that: wherein, article one, the top of helical duct and bottom are for sealing, and the spiral center bottom termination refrigerating medium inlet pipe (5) of this helical duct is outside the logical tank body of refrigerating medium inlet pipe, the outer rim upper end of helical duct is carried cryogen and is gone out pipe (6), and refrigerating medium goes out outside the logical tank body of pipe; The top of another helical duct and bottom are uncovered, up/down perforation; Tank base is provided with gaseous mixture inlet pipe (8), and tank body top is established silane gas and gone out pipe (9).

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