CN112520697A - Method for absorbing hydrogen chloride by STC circulating spraying - Google Patents
Method for absorbing hydrogen chloride by STC circulating spraying Download PDFInfo
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- CN112520697A CN112520697A CN202011401036.2A CN202011401036A CN112520697A CN 112520697 A CN112520697 A CN 112520697A CN 202011401036 A CN202011401036 A CN 202011401036A CN 112520697 A CN112520697 A CN 112520697A
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen; Reversible storage of hydrogen
- C01B3/50—Separation of hydrogen or hydrogen-containing gases from gaseous mixtures, e.g. purification
- C01B3/52—Separation of hydrogen or hydrogen-containing gases from gaseous mixtures, e.g. purification by contacting with liquids; Regeneration of used liquids
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/08—Compounds containing halogen
- C01B33/107—Halogenated silanes
- C01B33/10778—Purification
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B7/00—Halogens; Halogen acids
- C01B7/01—Chlorine; Hydrogen chloride
- C01B7/07—Purification ; Separation
- C01B7/0706—Purification ; Separation of hydrogen chloride
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Abstract
The invention belongs to the technical field of tail gas treatment, and particularly relates to a method for absorbing hydrogen chloride by STC circulating spraying. The method comprises the following steps: hydrogen, hydrogen chloride, dichlorosilane, trichlorosilane and silicon tetrachloride in tail gas sent out by a reduction workshop enter a leaching tower after low-temperature condensation; after non-condensable hydrogen and hydrogen chloride are compressed and pressurized, the hydrogen chloride is dissolved in the silicon tetrachloride by using the silicon tetrachloride as an absorbent under the conditions of high pressure and low temperature, the hydrogen chloride is absorbed, and the hydrogen is separated out; removing trace chlorosilane still contained in the separated hydrogen through an adsorption tower so as to obtain pure hydrogen without other impurities; the hydrogen chloride absorbed by the silicon tetrachloride is desorbed and separated by an analytical tower under the condition of temperature rise, and the like. In the method, pure STC is used for absorbing hydrogen chloride to improve the quality of hydrogen, so that the silane content in the obtained hydrogen is obviously less than 0.02 percent; the circulation volume is small, and the electric quantity consumption is reduced to achieve the purposes of quality improvement and efficiency improvement.
Description
Technical Field
The invention belongs to the technical field of tail gas treatment, and particularly relates to a method for absorbing hydrogen chloride by STC circulating spraying.
Background
Polycrystalline silicon is widely used as a chemical material in semiconductor devices, solar cells, and the like. With the rapid development of the electronic information industry and the solar photovoltaic industry, the market demand for polysilicon is increasing. However, in the mainstream process for preparing the polysilicon at present, trichlorosilane is reduced into crystalline silicon by hydrogen in a reducing furnace, and the reduction tail gas contains a large amount of unreacted hydrogen, hydrogen chloride, dichlorosilane, silicon trichloride and silicon tetrachloride, and many of the tail gas can be recycled as raw materials.
At present, the processes for treating and recovering tail gas include wet recovery, membrane separation recovery and dry recovery.
The absorption tower temperature required by the existing process is lower, and the refrigeration load of a refrigerator needs to be increased so as to achieve stable and lower spraying temperature and ensure the product quality of recovered hydrogen. Meanwhile, the existing process needs larger liquid phase circulating spraying amount under the condition of large air quantity. Both of these items require greater electrical energy to be consumed to achieve the desired quality of recovered hydrogen. Therefore, the invention can reduce the power consumption while achieving the same level of quality of recovered hydrogen.
Disclosure of Invention
The invention aims to provide a method for absorbing hydrogen chloride by STC circulating spraying, aiming at the defects of the prior art. The method utilizes the principle that the solubility of hydrogen in silicon tetrachloride is low, and the solubility of hydrogen chloride in STC is higher than that of TCS, and uses pure STC to absorb hydrogen chloride to improve the quality of hydrogen and reduce the consumption of electric quantity so as to achieve the purposes of quality improvement and efficiency improvement.
In order to achieve the above purpose, the specific technical scheme of the invention is as follows:
a method for absorbing hydrogen chloride by STC cyclic spraying comprises the following steps: hydrogen, hydrogen chloride, dichlorosilane, trichlorosilane and silicon tetrachloride in tail gas sent out by a reduction workshop are condensed at low temperature and then enter a leaching tower for condensation; after non-condensable hydrogen and hydrogen chloride are compressed and pressurized, the hydrogen chloride is dissolved in the silicon tetrachloride by using the silicon tetrachloride as an absorbent under the conditions of high pressure and low temperature, the hydrogen chloride is absorbed, and the hydrogen is separated out; removing trace hydrogen chloride still contained in the separated hydrogen through an adsorption tower so as to obtain pure hydrogen without other impurities, and storing the pure hydrogen in a hydrogen tank for the next process; the hydrogen chloride absorbed by the silicon tetrachloride is resolved and separated by a resolving tower under the condition of temperature rise; cooling the separated hydrogen chloride into liquid, sending one part of the liquid to a low-pressure condensation section, and sending the other part of the liquid to a cold hydrogenation process after heat exchange; one part of the separated silicon tetrachloride is used for recycling in the absorption tower, and the other part is sent to the rectification and purification process.
As a preferred embodiment of the present application, the absorbent used in the absorption tower is pure silicon tetrachloride, and the purity thereof is 99.99% or more.
As a preferred embodiment of the present application, the temperature of the tail gas entering the absorber is from-45 ℃ to-55 ℃; it is further preferred that the temperature of the off-gas entering the absorber is from-48 ℃ to-52 ℃.
As a preferred embodiment of the present application, the circulation flow rate of the lean solution is 100m3/h-300m3H; it is further preferable that the lean solution has a circulation flow rate of 150m3/h。
As a better embodiment in the application, the spraying speed of the silicon tetrachloride is 10-20T/h.
As a better implementation mode in the application, silicon tetrachloride in the desorption tower and the absorption tower needs to be continuously supplemented by pumps so as to ensure the concentration of the silicon tetrachloride.
As a preferred embodiment of the present application, the feeding amount of the reduction tail gas is 0 to 150T.
The main scheme and the further selection schemes can be freely combined to form a plurality of schemes which are all adopted and claimed by the invention; in the invention, the selection (each non-conflict selection) and other selections can be freely combined. The skilled person in the art can understand that there are many combinations, which are all the technical solutions to be protected by the present invention, according to the prior art and the common general knowledge after understanding the scheme of the present invention, and the technical solutions are not exhaustive herein.
Compared with the prior art, the invention has the beneficial effects that:
in the method, pure STC is used for absorbing hydrogen chloride to improve the quality of hydrogen, so that the content of silane in the obtained hydrogen is obviously less than 0.02 percent.
And (II) the circulation volume is small, and the electricity consumption is reduced to achieve the purposes of quality improvement and efficiency improvement.
And (III) the spraying temperature of the system can be correspondingly increased to be higher than minus 45 ℃ to minus 40 ℃, and the refrigeration load can be greatly reduced. The power consumption of one refrigerating machine can be saved by 1200 KW/h. Meanwhile, the use of a liquid phase silane circulating pump is saved, and the electric quantity is saved by 135 KW/h. The electricity consumption can be saved by 534 ten thousand yuan per year by calculating 8000h and 0.5 yuan per year.
Drawings
FIG. 1 is a schematic diagram of a process flow for absorbing hydrogen chloride by STC cyclic spraying in example 1 of the present invention.
Detailed Description
A method for absorbing hydrogen chloride by STC cyclic spraying comprises the following steps: hydrogen, hydrogen chloride, dichlorosilane, silicon trichloride and silicon tetrachloride in tail gas sent out by a reduction workshop are condensed at low temperature and then enter an absorption tower for condensation; after non-condensable hydrogen and hydrogen chloride are compressed and pressurized, the hydrogen chloride is dissolved in the silicon tetrachloride by using the silicon tetrachloride as an absorbent under the conditions of high pressure and low temperature, the hydrogen chloride is absorbed, and the hydrogen is separated out; removing trace hydrogen chloride still contained in the separated hydrogen through an adsorption tower so as to obtain pure hydrogen without other impurities, and storing the pure hydrogen in a hydrogen tank for the next process; the hydrogen chloride absorbed by the silicon tetrachloride is resolved and separated by a resolving tower under the condition of temperature rise; cooling the separated hydrogen chloride into liquid, sending one part of the liquid to a low-pressure condensation section, and sending the other part of the liquid to a cold hydrogenation process after heat exchange; one part of the separated silicon tetrachloride is used for recycling in the absorption tower, and the other part is sent to the rectification and purification process.
As a preferred embodiment of the present application, the absorbent used in the absorption tower is pure silicon tetrachloride, and the purity thereof is 99.99% or more.
As a preferred embodiment of the present application, the temperature of the tail gas entering the absorber is from-45 ℃ to-55 ℃; it is further preferred that the temperature of the off-gas entering the absorber is from-48 ℃ to-52 ℃.
As a preferred embodiment of the present application, the circulation flow rate of the lean solution is 100m3/h-300m3H; it is further preferable that the lean solution has a circulation flow rate of 150m3/h。
As a better implementation mode in the application, the renewed injection speed of the silicon tetrachloride is 10-20T/h. As a better implementation mode in the application, silicon tetrachloride in the desorption tower and the absorption tower needs to be continuously supplemented by pumps so as to ensure the concentration of the silicon tetrachloride.
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict.
It should be noted that, in order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings or the orientations or positional relationships that the products of the present invention are conventionally placed in use, and are only used for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.
Furthermore, the terms "horizontal", "vertical", "overhang" and the like do not imply that the components are required to be absolutely horizontal or overhang, but may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.
In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
In addition, it should be noted that, in the present invention, if the specific structures, connection relationships, position relationships, power source relationships, and the like are not written in particular, the structures, connection relationships, position relationships, power source relationships, and the like related to the present invention can be known by those skilled in the art without creative work on the basis of the prior art.
In the present application,%, unless otherwise specified, means% by volume.
In the application, E-80601 (E-01 for short), E-80602 (E-02 for short), E-80603 (E-03 for short), E-80604 (E-04 for short), E-80605 (E-05 for short), E-80606 (E-06 for short), an absorption tower T80602 (T02 tower for short), and a desorption tower T80603 (T03 tower for short).
Example 1:
as shown in figure 1, the invention discloses a method for absorbing hydrogen chloride by STC circulating spraying.
When the reduction feed amount reaches 120T, the reduction tail gas is at 120 ℃ and 4.8bar, and the reduction tail gas is 90949m3The flow rate of/h enters a reduction tail gas air cooler E-80601 through an electric valve of XV0101, and the temperature of a medium is 60 ℃ and the pressure is 4.75bar after the medium is cooled by E-01. Then enters a reduction tail gas circulating water cooler E-80602 tube pass, and the medium is cooled to 42 ℃. Then enters a tube pass of a reduction tail gas-gas heat exchanger E80603, enters a tube pass of a reduction tail gas primary chilled water heat exchanger E80604, and the medium is cooled to 22 ℃. And then the mixture enters a reduction tail gas secondary chilled water cooler E80605 to cool the medium to 13 ℃, and then the medium is mixed with the condensate of E02, E03, E04 and E05 tube passes through an XV0301 electric valve and then enters a leaching tower T80601 at the pressure of 4.55 bar. Chlorosilane liquid enters the leacheate circulating pump P80601 from the bottom of the tower. Part of the pump outlet (1.7MPa) is sent to the rectification system through regulating valves LV0301, LV0601, LV1601, LV1901 perchloro silane filtering device X80602. Another part is at 130m3The flow rate/h enters a pipe pass of an eluent heat exchanger E80606, the hydrogen chloride sent from a shell pass E80623 is cooled to 13 ℃ after heat exchange, then enters an eluent cooler E80607 pipe pass and is cooled to-12.27 ℃ to be mixed with chlorosilane sent from a chlorosilane condensate buffer tank V80601(E08, E09, E10, E11, E12 and E13 pipe pass condensate), and then enters the top of a T80601 to be sprayed to remove amorphous silicon in tail gas and cool the tail gas. The sprayed tail gas comes out from the top of the T80601Entering E80603 shell pass through TV2701A/B, TV2801A/B to adjust the temperature to 5 ℃ and the flow rate to 77306m3And h, the pressure is 4.5bar, and the gas enters a reducing tail gas compressor inlet gas buffer tank V80602. Then 77306m3And/h, entering a hydrogen compressor C80601, compressing to 1.3MPa, and entering a reduction tail gas compressor outlet gas buffer tank V80603 at the temperature of 42 ℃.
Then enters a primary compressed gas heat exchanger E80608 tube side and is cooled to 24.51 ℃. Then enters a compressed air freezing water cooler E80609 tube pass, and then enters a secondary compressed air heat exchanger E80610 tube pass, and the temperature is reduced to-0.67 ℃. Then enters a compressed gas cooler E80611 tube side (the shell side is-30 ℃ R507A) to be cooled to-20 ℃, then enters a three-stage compressed gas heat exchanger E80612 tube side to be cooled to-29.9 ℃, then enters a compressed gas chiller E80613 tube side to be cooled to-45 ℃ by-55 ℃ R507A, and then enters the bottom of an absorption tower T80602.
After passing through the tube pass of the first-stage lean and rich liquid heat exchanger E80615, chlorosilane rich liquid at the bottom of the T80602 enters a second-stage lean and rich liquid heat exchanger E80617 at the temperature of-29.9 ℃, then enters a third-stage lean and rich liquid heat exchanger E80619 at the temperature of-0.88 ℃, then enters a liquid pumped by a regulating valve LV1001 and P01 at the temperature of 19 ℃, enters a fourth-stage lean and rich liquid heat exchanger E80620, and then enters a desorption tower T80603 at the temperature of 65 ℃.
The T03 column pressure was controlled at 5bar and the column still temperature was 120 ℃. The reboiler E80622 at the bottom of the tower is 2bar, the steam flow at the temperature of 133 ℃ is 5.6T/h, the condenser E80623 at the top of the tower condenses the hydrogen chloride to-45 ℃, the temperature of part of the condensed hydrogen chloride is 13 ℃ after the condensed hydrogen chloride is sent to an E06 heat exchanger, and the flow is 802.8m3And/h, part of the liquid phase is directly extracted to a low-pressure condensation section E05 to remove dichlorosilane and trichlorosilane. One part of chlorosilane barren solution without hydrogen chloride enters an E20 shell pass, the other part of chlorosilane barren solution is mixed after passing through an adjusting valve TV1302 and enters a barren solution circulating water cooler E80621 shell pass, a small part of chlorosilane barren solution is sent to rectification from a P80602, and a large part of chlorosilane barren solution is sent to an E19 shell pass (150 m) from a barren solution circulating pump P80602 (the total volume of the chlorosilane barren solution is 150 m)3H,42 ℃ and 2.5MPa), exchanging heat to 22.481 ℃, then entering a barren solution chilled water cooler E80618 tube pass, entering an E17 shell pass, cooling to-16 ℃, then entering a barren solution cooler E80616 tube pass (the shell pass is-30 ℃ R507A), cooling to-20 ℃, then entering an E15 shell pass for continuous cooling, after cooling to-32.3 ℃, entering a barren solution deep cooler E80614 shell pass (the tube pass is R507A), and then taking 150m3Circulation of/hThe mixture is added into a T02 tower for spraying, and the temperature in the T02 tower is controlled to be-53 ℃.
The tail gas absorbed by the T02 tower enters an E12 shell pass, enters an E10 shell pass after the temperature is-30.9 ℃, enters an E08 shell pass after the temperature is-1.672 ℃ after the temperature is E10, enters an E08 shell pass after the temperature is E08, enters a filter at the pressure of 23 ℃, enters a pressure regulating valve PV3801/PV3802 after the pressure is 13bar, and enters a pure hydrogen buffer tank V80608 (the temperature is 40 ℃, the pressure is 1.3MPa, and the flow is 71100 m)3And/h) carrying out reduction, rectification, hydrogen chloride synthesis and cold hydrogenation.
When the system is started, STC with the purity of 99.99 percent is injected into the T02 tower and the T03 tower, and the STC concentration is reduced when the T02 tower and the T03 tower circulate due to the fact that trace chlorosilane is carried in absorption gas in the absorption process, so that STC with the purity of 99.99 percent is supplemented into the T03 tower to keep high concentration. The supplement speed is kept at about 15T/h to keep the high concentration of the spray material.
Through detection, the spraying result is recorded as follows:
from the above, the content of hydrogen chloride, dichlorodisilane, trichlorosilane, tetrachlorosilane and the like in the gas phase obtained after spraying is low, and the spraying effect of the method is good.
Example 2:
the operation was carried out in the same manner as in example 1 except that the circulating amount of the spray introduced into TO2 was controlled TO 150m3The silicon tetrachloride concentration was reduced to 95.79% and the spraying results were as follows:
| hydrogen chloride% | Dichlorodisilane% | Trichlorosilane% | Tetrachlorosilane% | |
| Spray material (liquid phase on top of absorption tower) | 0.03 | 2.0 | 2.18 | 95.79 |
| Outlet gas (gas phase coming out after spraying) | / | / | 0.001 | 0.009 |
Example 3:
the operation was carried out in the same manner as in example 1 except that the circulating amount of the spray entering TO2 was controlled TO 150m3The silicon tetrachloride concentration is reduced to 86.05 percent, and the spraying results are as follows:
example 4:
the operation was carried out in the same manner as in example 1, namely by absorption of hydrogen chloride by STC cyclic spraying. The difference is only that the spraying circulation quantity entering T02 is controlled to be 150m3The silicon tetrachloride concentration is reduced to 82.4 percent, and the spraying results are as follows:
| hydrogen chloride% | Dichlorodisilane% | Trichlorosilane% | Tetrachlorosilane% | |
| Spray material (liquid phase on top of absorption tower) | 0.04 | 7.81 | 9.71 | 82.4 |
| Outlet gas (gas phase coming out after spraying) | / | / | 0.007 | 0.008 |
Example 5:
the operation was carried out in the same manner as in example 1, except that the circulation amount of the spray entering T02 was kept at 150m3The STC concentration is ensured to be about 90%; when the reduction feeding amount is 60T, the spraying result is as follows:
| hydrogen chloride% | Dichlorodisilane% | Trichlorosilane% | Tetrachlorosilane% | |
| Spray material (liquid phase on top of absorption tower) | 0.02 | 4.59 | 6.11 | 89.28 |
| Outlet gas (gas phase coming out after spraying) | / | / | 0.002 | 0.005 |
Example 6:
the operation was carried out in the same manner as in example 1, except that the circulation amount of the spray entering T02 was kept at 150m3The feeding amount of the reducing gas is 60T, and when the reducing gas is sprayed by original low-concentration silicon tetrachloride (the concentration is about 50 percent), the spraying result is as follows:
example 7:
with fruitExample 6 the same, except that the spray circulation volume into T02 was 220m3The spray results were as follows:
| hydrogen chloride% | Dichlorodisilane% | Trichlorosilane% | Tetrachlorosilane% | |
| Spray material (liquid phase on top of absorption tower) | 0.04 | 6.25 | 50.47 | 43.24 |
| Outlet gas (gas phase coming out after spraying) | / | 0.011 | 0.015 | 0.019 |
Example 8:
the only difference was that the spray circulation into T02 was 150m, as in example 63And h, when the STC concentration is about 93 percent and the feeding amount (gas amount) of reducing gas is 80T, the spraying results are as follows:
| hydrogen chloride% | Dichlorodisilane% | Trichlorosilane% | Tetrachlorosilane% | |
| Spray material (liquid phase on top of absorption tower) | 0.08 | 1.79 | 4.74 | 93.39 |
| Outlet gas (gas phase coming out after spraying) | / | / | 0.004 | 0.007 |
Example 9:
as in example 6, with the only difference that the reducing gas feed was 80T, the results after spraying were as follows:
| hydrogen chloride% | Dichlorodisilane% | Trichlorosilane% | Tetrachlorosilane% | |
| Spray material (liquid phase on top of absorption tower) | 0.04 | 6.25 | 50.47 | 43.24 |
| Outlet gas (gas phase coming out after spraying) | / | 0.026 | 0.070 | 0.023 |
Example 10:
the only difference was that the circulation volume of the spray entering T02 was 220m, as in example 13When the feeding amount (gas amount) of the reducing gas is 80T and the original low-concentration silicon tetrachloride (the concentration is about 50 percent) is sprayed, the spraying results are as follows:
| hydrogen chloride% | Dichlorodisilane% | Trichlorosilane% | Tetrachlorosilane% | |
| Spray material (liquid phase on top of absorption tower) | 0.04 | 6.25 | 50.47 | 43.24 |
| Outlet gas (gas phase coming out after spraying) | / | 0.022 | 0.052 | 0.012 |
Example 11:
the operation was carried out in the same manner as in example 1 except that the circulating amount of the spray introduced into TO2 was controlled TO 150m3And h, when the STC concentration is about 90 percent and the feeding amount (gas amount) of reducing gas is 100T, the spraying results are as follows:
| hydrogen chloride% | Dichlorodisilane% | Trichlorosilane% | Tetrachlorosilane% | |
| Spray material (liquid phase on top of absorption tower) | 0.05 | 0.68 | 8 | 91.27 |
| Outlet gas (gas phase coming out after spraying) | / | / | 0.008 | 0.008 |
Example 12:
as in example 1, the only difference was that the circulation volume into the TO2 shower was 150m3When the feeding amount (gas amount) of the reducing gas is 100T and the original low-concentration silicon tetrachloride (the concentration is about 50%) is sprayed, the spraying results are as follows:
| hydrogen chloride% | Dichlorodisilane% | Trichlorosilane% | Tetrachlorosilane% | |
| Spray material (liquid phase on top of absorption tower) | 0.04 | 6.25 | 50.47 | 43.24 |
| Outlet gas (gas phase coming out after spraying) | / | 0.024 | 0.083 | 0.021 |
Example 13:
the operation was carried out in the same manner as in example 1 except that the amount of spray circulation into TO2 was controlled TO 220m3When the feeding amount (gas amount) of the reducing gas is 100T and the original low-concentration silicon tetrachloride (the concentration is about 50%) is sprayed, the spraying results are as follows:
| hydrogen chloride% | Dichlorodisilane% | Trichlorosilane% | Tetrachlorosilane% | |
| Spray material (liquid phase on top of absorption tower) | 0.04 | 6.25 | 50.47 | 43.24 |
| Outlet gas (gas phase coming out after spraying) | / | 0.012 | 0.053 | 0.015 |
From the spraying results of examples 5 to 13, it can be seen that the higher the purity of silicon tetrachloride is, the better the absorption effect is, and the higher the purity of the obtained hydrogen is, without changing other conditions. When the gas amount is increased, the high-purity STC is sprayed, so that the purity of the hydrogen can be maintained.
Example 14: using STC spray absorption to test the influence of different spray temperatures on the absorption effect:
the absorption operation was carried out in the same manner as in example 1, except that the circulation amount was 150m at the same gas amount3Spraying with high-purity silicon tetrachloride (the purity reaches 99.99%) at the temperature of-54.5 ℃ in the hour, wherein the spraying results are as follows:
spraying with high-purity silicon tetrachloride, raising the spraying temperature, and ensuring that the purity of the hydrogen obtained without an adsorption system is 99.99%.
The foregoing basic embodiments of the invention and their various further alternatives can be freely combined to form multiple embodiments, all of which are contemplated and claimed herein. In the scheme of the invention, each selection example can be combined with any other basic example and selection example at will. Numerous combinations will be known to those skilled in the art.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (8)
1. The method for absorbing the hydrogen chloride by STC circulating spraying is characterized by comprising the following steps: hydrogen, hydrogen chloride, dichlorosilane, trichlorosilane and silicon tetrachloride in tail gas sent out by a reduction workshop enter a leaching tower after low-temperature condensation; after non-condensable hydrogen and hydrogen chloride are compressed and pressurized, the hydrogen chloride is dissolved in the silicon tetrachloride by using the silicon tetrachloride as an absorbent under the conditions of high pressure and low temperature, the hydrogen chloride is absorbed, and the hydrogen is separated out; removing trace chlorosilane still contained in the separated hydrogen through an adsorption tower so as to obtain pure hydrogen without other impurities, and storing the pure hydrogen in a hydrogen tank for the next process; the hydrogen chloride absorbed by the silicon tetrachloride is resolved and separated by a resolving tower under the condition of temperature rise; cooling the separated hydrogen chloride into liquid, sending one part of the liquid to a low-pressure condensation section, and sending the other part of the liquid to a cold hydrogenation process after heat exchange; one part of the separated silicon tetrachloride is used for recycling in the absorption tower, and the other part is sent to the rectification and purification process.
2. The process for the absorption of hydrogen chloride by STC cyclic spraying of claim 1, wherein: the absorbent adopted in the absorption tower is pure silicon tetrachloride with the purity of more than 99.99 percent.
3. The process for the absorption of hydrogen chloride by STC cyclic spraying of claim 1, wherein: the temperature of the tail gas entering the absorption tower is between 45 ℃ below zero and 55 ℃ below zero.
4. The process for the absorption of hydrogen chloride by STC cyclic spraying of claim 3, wherein: the temperature of the tail gas entering the absorption tower is-48 ℃ to-52 ℃.
5. Such as rightThe method for absorbing hydrogen chloride by STC cyclic spraying according to claim 1, wherein: the circulation flow rate of the lean solution was 100m3/h-300m3/h。
6. The process for the absorption of hydrogen chloride using STC cyclic spray of claim 5, wherein: the circulation flow rate of the lean solution was 150m3/h。
7. The process for the absorption of hydrogen chloride by STC cyclic spraying of claim 1, wherein: the spraying speed of the silicon tetrachloride is 10-20T/h.
8. The process for the absorption of hydrogen chloride by STC cyclic spraying of claim 2, wherein: the silicon tetrachloride in the desorption tower and the absorption tower needs to be continuously supplemented by a pump so as to ensure the concentration of the silicon tetrachloride.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011401036.2A CN112520697A (en) | 2020-12-04 | 2020-12-04 | Method for absorbing hydrogen chloride by STC circulating spraying |
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