CN113277471A - Method and device for recovering reduction tail gas in polycrystalline silicon production - Google Patents
Method and device for recovering reduction tail gas in polycrystalline silicon production Download PDFInfo
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- C01B3/50—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification
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Abstract
The invention discloses a method for recovering reduction tail gas in polycrystalline silicon production, which comprises the following steps: a, conveying the reduction tail gas into a cooling system, and separating to obtain tail gas and chlorosilane condensate; b, conveying the tail gas and the chlorosilane condensate into a leaching device for leaching; c, sequentially compressing and cooling the leached tail gas; d, sending the tail gas into an absorption tower to absorb hydrogen chloride gas in the tail gas, obtaining chlorosilane rich liquid at the bottom of the absorption tower, and obtaining tail gas rich in hydrogen at the top of the absorption tower; e, conveying the chlorosilane rich solution into a desorption tower, obtaining hydrogen chloride at the top of the desorption tower, obtaining a chlorosilane poor solution at the bottom of the desorption tower, and conveying the chlorosilane poor solution and the chlorosilane rich solution into an absorption tower to be used as an absorption solution after heat exchange; and f, sending the tail gas rich in hydrogen into a hydrogen adsorption device to obtain hydrogen. The recovery method can fully recover the cold energy, obviously reduces the investment and operation cost, has high quality of the separated and recovered hydrogen, and can meet the requirement of polysilicon production.
Description
Technical Field
The invention belongs to the technical field of polycrystalline silicon production, particularly relates to a method for recovering reduction tail gas in polycrystalline silicon production, and particularly relates to a device for recovering reduction tail gas in polycrystalline silicon production.
Background
In the production of polycrystalline silicon, the reduction tail gas output from the reduction furnace mainly comprises H2HCl gas, and gas phase chlorosilanes, etc., wherein the gas phase chlorosilanes include SiHCl3Gas, SiCl4Gas and SiH2Cl2The method comprises the following steps that (1) a mixture of gases and reduction tail gas need to enter a tail gas recovery system for recovery treatment so as to recover hydrogen, hydrogen chloride and chlorosilane in the mixture, and at present, the recovery process of the reduction tail gas mainly comprises the following three steps: wet recovery, dry recovery and membrane separation recovery.
The wet tail gas recovery process can cause great material loss and higher cost, the membrane separation tail gas recovery process has the technical problems of high pressure, harsh separation membrane use conditions and the like, the dry tail gas recovery process is simple to realize, and the polycrystalline silicon tail gas can be completely recycled, so that the whole polycrystalline silicon production system achieves closed cycle, the consumption of raw materials and power energy can be reduced, and the aims of reducing pollution and protecting the environment can be fulfilled. However, the problems of insufficient cold source utilization, high energy consumption, low purity of the recovered hydrogen and the like generally exist in the conventional dry recovery process, so that the recovery method of the reduction tail gas in the production of the polycrystalline silicon, which can fully recycle the cold source, reduce the energy consumption and improve the purity of the recovered hydrogen, needs to be developed.
Disclosure of Invention
The present invention is based on the discovery and recognition by the inventors of the following facts and problems: in the dry-method tail gas recovery process, firstly, the entering reduction tail gas is cooled, and most of chlorosilane in the reduction tail gas is condensed by utilizing the difference of the boiling points of components in the reduction tail gas, so that non-condensable gas (namely mixed gas of hydrogen, hydrogen chloride and a small amount of chlorosilane) is separated from liquid-phase chlorosilane. And introducing the non-condensable gas into an absorption tower, and absorbing hydrogen chloride impurities in the non-condensable gas by using barren liquor chlorosilane from a desorption tower, thereby completing the separation of hydrogen chloride from the reduction tail gas. And purifying the hydrogen containing a small amount of hydrogen chloride output from the top of the absorption tower by an adsorption column to obtain pure hydrogen, and outputting rich liquid chlorosilane containing a large amount of hydrogen chloride from the tower kettle of the absorption tower. And (3) the rich liquid chlorosilane enters an analytical tower to separate out light components to form barren liquid chlorosilane, the barren liquid chlorosilane is sent to an absorption tower to absorb hydrogen chloride impurities in the non-condensable gas, and the separated hydrogen, hydrogen chloride and chlorosilane are respectively sent to an upstream procedure and a downstream procedure for recycling, so that the reduction tail gas is developed from open production to closed cycle production.
In the related technology, CN207792717U discloses a recovery system for chlorosilane in tail gas in polysilicon production, and in the patent, an adsorption tower adopts a coil type heat conduction oil heating mode, so that the adsorption process is complex and the energy consumption is high.
CN104923026B discloses a method and a device for recovering polysilicon tail gas, in the earlier stage treatment of the reduction tail gas, only the polysilicon tail gas is subjected to condensation treatment to condense chlorosilane in the polysilicon tail gas into liquid, the cold source is single, and the cold source is not fully recycled.
CN109200754A discloses an adsorption equipment who is applied to polycrystalline silicon reduction tail gas recovery system. Adopt single adsorbent to carry out hydrogen adsorption edulcoration in this patent, the edulcoration rate is low, can't get rid of impurity such as boron and phosphorus, and gained hydrogen product quality is relatively poor.
CN104402001B discloses a polysilicon hydrogenation tail gas recovery system and a tail gas utilization method, and the patent discloses that separation of hydrogen chloride adopts the form of liquid hydrogen chloride for recovery, and energy consumption is high.
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art.
Therefore, the embodiment of the first aspect of the invention provides a method for recovering the reduction tail gas in the production of polycrystalline silicon, which can fully recover the cold energy, obviously reduce the investment and operation cost, ensure high quality of the separated and recovered hydrogen and meet the requirement of the subsequent production of polycrystalline silicon.
According to the embodiment of the first aspect of the invention, the method for recovering the reduction tail gas in the production of the polycrystalline silicon comprises the following steps:
a. sending the reduction tail gas into a cooling system, and separating to obtain tail gas and chlorosilane condensate;
b. b, sending the tail gas obtained in the step a and the chlorosilane condensate into a leaching device, so that the chlorosilane condensate leaches the tail gas;
c. sequentially compressing and cooling the tail gas subjected to leaching treatment in the step b to obtain high-pressure tail gas;
d. c, sending the high-pressure tail gas obtained in the step c into an absorption tower, absorbing hydrogen chloride in the tail gas by using chlorosilane as absorption liquid, obtaining a chlorosilane rich solution rich in hydrogen chloride at the bottom of the absorption tower, and obtaining a tail gas rich in hydrogen at the top of the absorption tower;
e. c, feeding the chlorosilane rich solution rich in hydrogen chloride obtained in the step d into a desorption tower, obtaining hydrogen chloride gas at the top of the desorption tower, obtaining a chlorosilane poor solution at the bottom of the desorption tower, and feeding the chlorosilane poor solution and the chlorosilane rich solution at the bottom of the step d into the absorption tower of the step d after heat exchange to be used as an absorption solution;
f. and d, sending the tail gas rich in hydrogen obtained in the step d into a hydrogen adsorption device to obtain hydrogen.
According to the advantages and technical effects brought by the independent claims of the embodiment of the first aspect of the invention, 1, in the recovery method of the embodiment of the invention, a leaching step is added after the reduction tail gas is cooled, the tail gas is leached by using the chlorosilane condensate obtained by cooling and separating, fine silicon powder in the tail gas can be completely leached, the fine silicon powder is prevented from being brought into a subsequent compression device and a subsequent cooling system along with the tail gas to cause adverse effects on the compression device and the cooling system, the service lives of the compression device and the cooling system are prolonged, the chlorosilane condensate can absorb hydrogen chloride gas in the tail gas while leaching the fine silicon powder in the tail gas, so that the effect of absorbing hydrogen chloride is realized, moreover, the chlorosilane entering the leaching device is low-temperature chlorosilane, after the tail gas is leached, the chlorosilane leaving the leaching device is in leaching contact with the tail gas to realize heat exchange, the tail gas temperature is reduced, the temperature of the chlorosilane is increased, and the cold energy of the chlorosilane is fully recovered, so that the leaching device additionally arranged in the embodiment of the invention realizes multiple functions of dedusting, absorption and cold energy recovery; 2. in the method provided by the embodiment of the invention, the tail gas after being washed is compressed and pressurized, so that the pressure of the tail gas is increased, the absorption tower runs under high pressure to complete absorption, the consumption of an absorbent can be reduced, and the demand on a refrigerant is reduced, thereby realizing the purpose of energy conservation, and the energy can be saved by more than 20% by adopting high-pressure absorption; 3. the method provided by the embodiment of the invention can fully recover the cold energy, the investment and operation cost is obviously reduced, the quality of the separated and recovered hydrogen is high, and the requirement of the subsequent polysilicon production can be met.
According to the embodiment of the first aspect of the invention, in the method for recovering the reduction tail gas in the production of polycrystalline silicon, the leaching device in the step b is a bubble column; and/or in the step b, sending the chlorosilane condensate after the tail gas is leached in the leaching device into the desorption tower in the step e to recover hydrogen chloride gas.
According to the embodiment of the first aspect of the invention, in the recovery method of the reduction tail gas in the polysilicon production, in the step e, the hydrogen chloride extracted from the top of the desorption tower is gas; and/or in the step e, an intercooler is arranged at the upper part of the desorption tower, and water with the temperature of 7 ℃ is used as a refrigerant.
According to the recovery method of the reduction tail gas in the polysilicon production, in the step c, the tail gas is compressed to the pressure of 1.1-1.5MPa (shown in the table).
According to the embodiment of the first aspect of the invention, in the step c, the compressed tail gas sequentially passes through the primary double-effect heat exchanger, the compressed tail gas freezing water cooler, the secondary double-effect heat exchanger, the compressed tail gas cooler, the tertiary double-effect heat exchanger and the compressed tail gas deep cooler and then enters the absorption tower in the step d, wherein the compressed tail gas freezing water cooler adopts water at 7 ℃, the compressed tail gas cooler adopts R507 at-30 ℃, and the compressed tail gas deep cooler adopts R507 at-55 ℃.
According to the recovery method of the reduction tail gas in the polysilicon production, in the embodiment of the first aspect of the invention, the tail gas rich in hydrogen obtained at the tower top in the step d sequentially passes through the three-stage double-effect heat exchanger, the two-stage double-effect heat exchanger and the one-stage double-effect heat exchanger to exchange heat with the tail gas compressed in the step c, and then enters the hydrogen adsorption device in the step f.
According to the embodiment of the first aspect of the invention, in the step c, the condensate generated after cooling the tail gas is mixed with the chlorosilane condensate obtained in the step a, and then the mixture is sent to the leaching device in the step b.
According to the embodiment of the first aspect of the invention, the method for recovering the reduced tail gas in the production of polycrystalline silicon comprises the steps that the hydrogen adsorption device in the step f comprises a first adsorption tower, a second adsorption tower and a third adsorption tower, and the first adsorption tower, the second adsorption tower and the third adsorption tower are all hollow cylinder structures with gas distributors arranged inside; the adsorbent in the first adsorption tower is in a state with adsorption capacity, the adsorbent in the second adsorption tower is in a state needing to be regenerated, the adsorbent in the third adsorption tower is in a state needing to be desorbed, the tail gas rich in hydrogen enters the first adsorption tower for adsorption to obtain purified hydrogen, part of the purified hydrogen is sequentially sent to the second adsorption tower and the third adsorption tower, and then is subjected to compression, cooling, boron removal and phosphorus removal treatment, and then is mixed with the purified hydrogen obtained from the first adsorption tower to obtain a hydrogen product; and/or the adsorbent used in the adsorption device is a combined adsorbent comprising a molecular sieve and activated carbon.
The embodiment of the second aspect of the invention also provides a recovery device of the reduction tail gas in the polysilicon production, which comprises a first cooling system, a leaching device, a first compression device, a second cooling system, an absorption tower, a desorption tower, a lean and rich liquid heat exchange system and a hydrogen adsorption device, wherein the leaching device is a bubble tower,
a gas outlet of the first cooling system is connected with a gas inlet of the leaching device, and a condensate outlet of the first cooling system is connected with a liquid inlet of the leaching device;
a gas outlet of the leaching device is connected with a gas inlet of the first compression device, and a liquid outlet of the leaching device is connected with a liquid inlet of the desorption tower;
a gas inlet of the second cooling system is connected with a gas outlet of the first compression device, and a gas outlet of the second cooling system is connected with a gas inlet of the absorption tower;
a gas outlet of the absorption tower is connected with a gas inlet of the hydrogen adsorption device, a liquid inlet of the absorption tower is connected with a barren solution outlet of the barren and rich solution heat exchange system, and a liquid outlet of the absorption tower is connected with a rich solution inlet of the barren and rich solution heat exchange system;
and a rich solution outlet of the lean and rich solution heat exchange system is connected with a liquid inlet of the desorption tower, and a lean solution inlet of the lean and rich solution heat exchange system is connected with a liquid outlet of the desorption tower.
According to the advantages and technical effects brought by the independent claims of the embodiment of the second aspect of the invention, 1, the recovery device of the embodiment of the invention is additionally provided with the leaching device behind the first cooling system, the tail gas is leached by the chlorosilane condensate obtained by cooling and separating, fine silicon powder in the tail gas can be completely leached, the fine silicon powder is prevented from being brought into a subsequent compression device and a subsequent cooling system along with the tail gas to cause adverse effects on the compression device and the cooling system, the service lives of the compression device and the cooling system are prolonged, the chlorosilane condensate can absorb hydrogen chloride gas in the tail gas while leaching the fine silicon powder in the tail gas, the effect of absorbing hydrogen chloride is realized, moreover, the chlorosilane entering the leaching device is low-temperature chlorosilane, after the tail gas is leached, the chlorosilane leaving the leaching device is in leaching contact with the tail gas to realize heat exchange, the tail gas temperature is reduced, the temperature of the chlorosilane is increased, and the cold energy of the chlorosilane is fully recovered, so that the leaching device additionally arranged in the embodiment of the invention realizes multiple functions of dedusting, absorption and cold energy recovery; 2. according to the recovery device provided by the embodiment of the invention, the first compression device is additionally arranged behind the leaching device, so that the leached tail gas is compressed and pressurized, the pressure of the tail gas is increased, the absorption tower runs under high pressure to complete absorption, the using amount of an absorbent can be reduced, the demand on a refrigerant is reduced, the purpose of energy conservation is realized, and the energy can be saved by more than 20% by adopting high-pressure absorption; 3. the recovery device provided by the embodiment of the invention can realize sufficient recovery of cold energy, the investment and operation cost is obviously reduced, the quality of the separated and recovered hydrogen is high, and the requirement of subsequent polycrystalline silicon production can be met.
According to the recovery device of the reduction tail gas in the polysilicon production, disclosed by the embodiment of the second aspect of the invention, the first cooling system comprises an air cooler, a water cooler, a gas-gas heat exchanger and a reduction tail gas chilled water cooler which are sequentially connected; and/or the second cooling system comprises a primary double-effect heat exchanger, a compressed tail gas freezing water cooler, a secondary double-effect heat exchanger, a compressed tail gas cooler, a tertiary double-effect heat exchanger and a compressed tail gas deep cooler which are sequentially connected; and/or the lean-rich solution heat exchange system comprises a lean solution freezing water cooler, a lean solution cooler and a lean solution deep cooler which are connected in sequence; and/or an intercooler is arranged at the upper part of the desorption tower; and/or the hydrogen adsorption device comprises a first adsorption tower, a second adsorption tower and a third adsorption tower which are connected in sequence; and/or the hydrogen absorption device is an empty cylinder structure with a gas distributor arranged inside.
Drawings
FIG. 1 shows a recovery apparatus for reduction offgas in the production of polycrystalline silicon according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
According to the embodiment of the first aspect of the invention, the method for recovering the reduction tail gas in the production of the polycrystalline silicon comprises the following steps:
a. sending the reduction tail gas into a cooling system, and separating to obtain tail gas and chlorosilane condensate;
b. b, sending the tail gas obtained in the step a and the chlorosilane condensate into a leaching device, so that the chlorosilane condensate leaches the tail gas;
c. sequentially compressing and cooling the tail gas subjected to leaching treatment in the step b to obtain high-pressure tail gas;
d. c, sending the high-pressure tail gas obtained in the step c into an absorption tower, absorbing hydrogen chloride in the tail gas by using chlorosilane as absorption liquid, obtaining a chlorosilane rich solution rich in hydrogen chloride at the bottom of the absorption tower, and obtaining a tail gas rich in hydrogen at the top of the absorption tower;
e. c, feeding the chlorosilane rich solution rich in hydrogen chloride obtained in the step d into a desorption tower, obtaining hydrogen chloride gas at the top of the desorption tower, obtaining a chlorosilane poor solution at the bottom of the desorption tower, and feeding the chlorosilane poor solution and the chlorosilane rich solution at the bottom of the step d into the absorption tower of the step d after heat exchange to be used as an absorption solution;
f. and d, sending the tail gas rich in hydrogen obtained in the step d into a hydrogen adsorption device to obtain hydrogen.
According to the advantages and technical effects brought by the independent claims of the embodiment of the first aspect of the invention, 1, in the recovery method of the embodiment of the invention, a leaching step is added after the reduction tail gas is cooled, the tail gas is leached by the chlorosilane condensate obtained by cooling and separating, fine silicon powder in the tail gas can be completely leached, the fine silicon powder is prevented from being brought into a subsequent compression device and a subsequent cooling system along with the tail gas to cause adverse effects on the compression device and the cooling system, the service lives of the compression device and the cooling system are prolonged, the chlorosilane condensate can absorb hydrogen chloride gas in the tail gas while leaching the fine silicon powder in the tail gas, so that the effect of absorbing hydrogen chloride is realized, moreover, the chlorosilane entering the leaching device is low-temperature chlorosilane, after the tail gas is leached, the chlorosilane leaving the leaching device is in leaching contact with the tail gas to realize heat exchange, the tail gas temperature is reduced, the temperature of the chlorosilane is increased, and the cold energy of the chlorosilane is fully recovered, so that the leaching device additionally arranged in the embodiment of the invention realizes multiple functions of dedusting, absorption and cold energy recovery; 2. in the method provided by the embodiment of the invention, the tail gas after being washed is compressed and pressurized, so that the pressure of the tail gas is increased, the absorption tower runs under high pressure to complete absorption, the consumption of an absorbent can be reduced, and the demand on a refrigerant is reduced, thereby realizing the purpose of energy conservation, and the energy can be saved by more than 20% by adopting high-pressure absorption; 3. the method provided by the embodiment of the invention can fully recover the cold energy, the investment and operation cost is obviously reduced, the quality of the separated and recovered hydrogen is high, and the requirement of the subsequent polysilicon production can be met.
According to the embodiment of the first aspect of the invention, in the method for recovering the reduction tail gas in the polysilicon production, the leaching device in the step b is a bubble column, and/or in the step b, the chlorosilane condensate after the tail gas is leached in the leaching device is sent to the desorption tower in the step e to recover the hydrogen chloride gas. In the embodiment of the invention, the leaching device is preferably a bubble tower, the reduction tail gas plays a role in dust removal through bubbling, fine silicon powder in the reduction tail gas can be effectively removed, the bubble tower can be optimized by adopting the existing bubble tower, 5-10 layers of tower plates are additionally arranged on the basis of the existing bubble tower according to the treatment gas amount, chlorosilane condensate after the tail gas is leached leaves the leaching device and enters a desorption tower, and hydrogen chloride gas in the chlorosilane condensate is further recovered.
According to the recovery method of the reduction tail gas in the polysilicon production, in the step c, the tail gas is compressed to the pressure of 1.1-1.5MPa (shown in the table). In the embodiment of the invention, the tail gas after leaching treatment is compressed and pressurized, preferably, the pressure of the tail gas reaches 1.1-1.5MPa (shown in the table), so that the absorption tower runs under high pressure, the consumption of an absorbent can be reduced, the demand on a refrigerant is reduced, the purpose of energy conservation is realized, and the pressurized absorption is also beneficial to the separation of chlorosilane.
According to the embodiment of the first aspect of the invention, in the step c, the compressed tail gas sequentially passes through a first-stage double-effect heat exchanger, a compressed tail gas freezing water cooler, a second-stage double-effect heat exchanger, a compressed tail gas cooler, a third-stage double-effect heat exchanger and a compressed tail gas deep cooler and then enters the absorption tower in the step d, wherein the compressed tail gas freezing water cooler adopts water at 7 ℃, the compressed tail gas cooler adopts R507 at-30 ℃, and the compressed tail gas deep cooler adopts R507 at-55 ℃; d, the tail gas rich in hydrogen obtained at the tower top in the step d sequentially passes through the three-stage double-effect heat exchanger, the secondary double-effect heat exchanger and the primary double-effect heat exchanger to exchange heat with the tail gas compressed in the step c, and then enters the hydrogen adsorption device in the step f; and in the step c, mixing the condensate generated after cooling the tail gas with the chlorosilane condensate obtained in the step a, and then sending the mixture into the leaching device in the step b. In the embodiment of the invention, multiple cold sources are adopted for carrying out step heat exchange and double-effect heat exchange before the compressed tail gas enters the absorption tower, most of chlorosilane in the compressed tail gas can be further separated, the low-temperature chlorosilane condensate is mixed with the chlorosilane condensate separated after the reduced tail gas in the step a is cooled, and the mixture enters the leaching device for leaching the tail gas.
According to the embodiment of the first aspect of the invention, in the recovery method of the reduction tail gas in the polysilicon production, in the step e, the hydrogen chloride extracted from the top of the desorption tower is gas. Different from the prior art for extracting liquid hydrogen chloride, in the embodiment of the invention, after the desorption tower separates chlorosilane and hydrogen chloride, gaseous hydrogen chloride is extracted from the tower top, so that a vaporizing device which is also needed after the liquid hydrogen chloride is extracted in the prior art is saved, and the gaseous hydrogen chloride is extracted from the tower top, so that the cold consumption of a condenser at the tower top of the desorption tower is reduced, the hydrogen chloride in chlorosilane rich liquid can be fully separated, the content of the hydrogen chloride in barren liquid entering the absorption tower is greatly reduced, the circulation quantity of the barren liquid is effectively reduced, the requirement on a cold source is reduced, and the operation cost of the device is reduced. Because the amount of the silicon chloride rich liquid to be treated by the desorption tower is large, preferably, an intercooler is arranged at the upper part of the desorption tower, and water with the temperature of 7 ℃ is used as a refrigerant, so that the load of a condenser at the top of the desorption tower is reduced, and the effect of further saving energy can be achieved.
According to the embodiment of the first aspect of the invention, the method for recovering the reduced tail gas in the production of polycrystalline silicon comprises the steps that the hydrogen adsorption device in the step f comprises a first adsorption tower, a second adsorption tower and a third adsorption tower, and the first adsorption tower, the second adsorption tower and the third adsorption tower are all hollow cylinder structures with gas distributors arranged inside; preferably, the adsorbent used in the adsorption device is a combined adsorbent comprising a molecular sieve and activated carbon. In the embodiment of the invention, the combined adsorbent comprising the molecular sieve and the activated carbon is adopted, compared with the single adsorbent activated carbon in the prior art, the adsorption capacity of an adsorption device can be effectively improved, the impurity removal rate is high, the adsorption tower is of a hollow cylinder structure with a gas distributor arranged inside, is similar to a storage tank, is free of a coil pipe inside and a jacket pipe outside, is simple in structure, small in non-condensable gas flow, simple to operate, low in energy consumption and good in economic benefit, and the traditional adsorber basically adopts an adsorber with a heat exchange structure, has multiple operation procedures, complex structure and poor heat transfer effect, can cause incomplete regeneration due to insufficient temperature rise or insufficient temperature reduction, influences the adsorption effect and purification purity of the activated carbon, is frequent in cold and hot alternation, and easily causes deformation and damage of equipment and the like.
According to the method for recovering the reduction tail gas in the polysilicon production, in the first aspect of the invention, a plurality of groups of hydrogen adsorption devices can be arranged in the step f, and each group of hydrogen adsorption devices comprises a first adsorption tower, a second adsorption tower and a third adsorption tower; the method comprises the following steps that an adsorbent in a first adsorption tower is in a state with adsorption capacity, an adsorbent in a second adsorption tower is in a state needing to be regenerated, an adsorbent in a third adsorption tower is in a state needing to be desorbed, tail gas rich in hydrogen enters the first adsorption tower to be adsorbed to obtain purified hydrogen, part of the purified hydrogen is sequentially sent to the second adsorption tower and the third adsorption tower, and then is subjected to compression, cooling, boron removal and phosphorus removal treatment and then is mixed with the purified hydrogen obtained by the first adsorption tower to obtain a hydrogen product. In the embodiment of the invention, an adsorption device is provided with adsorption towers in three processes of adsorption, regeneration and desorption, tail gas rich in hydrogen from the adsorption towers is introduced into a first adsorption tower in a high-pressure low-temperature adsorption state for adsorption, impurities are adsorbed by active carbon and a molecular sieve combined adsorbent to further purify the hydrogen to obtain high-purity hydrogen, part of the hydrogen is led out from a high-purity hydrogen product and is introduced into a second adsorption tower in a regeneration state, the cold energy carried by the low-temperature hydrogen is utilized to cool the second adsorption tower, a third adsorption tower is in a desorption state, the hydrogen from the second adsorption tower is heated to high temperature by a heating system and then is sent into the third adsorption tower for heating and desorption, the hydrogen from the third adsorption tower is firstly cooled to normal temperature by a water cooler and then enters a compression system and a cooling system, and the cooled hydrogen is further subjected to boron removal and phosphorus removal treatment, separating out the enriched boron and phosphorus compounds. The high-purity hydrogen after boron and phosphorus removal and the high-purity hydrogen from the first adsorption tower form a final high-purity hydrogen product.
As shown in fig. 1, an embodiment of the second aspect of the present invention provides an apparatus 100 for recovering a reduction tail gas in polysilicon production, which comprises a first cooling system 1, a leaching apparatus 2, a first compression apparatus 3, a second cooling system 4, an absorption tower 5, a desorption tower 6, a lean-rich liquid heat exchange system 7 and a hydrogen adsorption apparatus, wherein a gas outlet of the first cooling system 1 is connected to a gas inlet of the leaching apparatus 2, and a condensate outlet of the first cooling system 1 is connected to a liquid inlet of the leaching apparatus 2; a gas outlet of the leaching device 2 is connected with a gas inlet of the first compression device 3, and a liquid outlet of the leaching device 2 is connected with a liquid inlet of the desorption tower 6; a gas inlet of the second cooling system 4 is connected with a gas outlet of the first compression device 3, and a gas outlet of the second cooling system 4 is connected with a gas inlet of the absorption tower 5; a gas outlet of the absorption tower 5 is connected with a gas inlet of the hydrogen adsorption device, a liquid inlet of the absorption tower 5 is connected with a barren solution outlet of the barren and rich solution heat exchange system 7, and a liquid outlet of the absorption tower 5 is connected with a rich solution inlet of the barren and rich solution heat exchange system 7; a rich solution outlet of the lean and rich solution heat exchange system 7 is connected with a liquid inlet of the desorption tower 6, and a lean solution inlet of the lean and rich solution heat exchange system 7 is connected with a liquid outlet of the desorption tower 6.
According to the advantages and technical effects brought by the independent claims of the embodiment of the second aspect of the invention, 1, the recovery device of the embodiment of the invention is additionally provided with the leaching device behind the first cooling system, the tail gas is leached by the chlorosilane condensate obtained by cooling and separating, fine silicon powder in the tail gas can be completely leached, the fine silicon powder is prevented from being brought into a subsequent compression device and a subsequent cooling system along with the tail gas to cause adverse effects on the compression device and the cooling system, the service lives of the compression device and the cooling system are prolonged, the chlorosilane condensate can absorb hydrogen chloride gas in the tail gas while leaching the fine silicon powder in the tail gas, the effect of absorbing hydrogen chloride is realized, the chlorosilane entering the leaching device is low-temperature chlorosilane, after the tail gas is leached, the chlorosilane leaving the leaching device is in leaching contact with the tail gas to realize heat exchange, the tail gas temperature is reduced, the temperature of the chlorosilane is increased, and the cold energy of the chlorosilane is fully recovered, so that the leaching device additionally arranged in the embodiment of the invention realizes multiple functions of dedusting, absorption and cold energy recovery; 2. according to the recovery device provided by the embodiment of the invention, the first compression device is additionally arranged behind the leaching device, so that the leached tail gas is compressed and pressurized, the pressure of the tail gas is increased, the absorption tower runs under high pressure to complete absorption, the using amount of an absorbent can be reduced, the demand on a refrigerant is reduced, the purpose of energy conservation is realized, and the energy can be saved by more than 20% by adopting high-pressure absorption; 3. the recovery device provided by the embodiment of the invention can realize sufficient recovery of cold energy, the investment and operation cost is obviously reduced, the quality of the separated and recovered hydrogen is high, and the requirement of subsequent polycrystalline silicon production can be met.
The recovery device for the reduction tail gas in the polysilicon production according to the embodiment of the second aspect of the invention, wherein the hydrogen adsorption device comprises a first adsorption tower 8, a second adsorption tower 9 and a third adsorption tower 11 which are connected in sequence, preferably, the first adsorption tower 8 is an empty cylinder structure with a gas distributor arranged inside, and the second adsorption tower 9 and the third adsorption tower 11 are the same as the first adsorption tower 8. Further preferably, a heating device 10 is arranged between the second adsorption tower 9 and the third adsorption tower 11, and a gas outlet of the third adsorption tower 11 is sequentially connected with a second compression device 12, a third cooling system 13 and a boron and phosphorus removal device 14. In the embodiment of the present invention, the adsorbent in the first adsorption tower 8 is in a state of having adsorption capacity, the adsorbent in the second adsorption tower 9 is in a state of requiring regeneration, and the adsorbent in the third adsorption tower 11 is in a state of requiring desorption. The adsorption device is provided with adsorption towers in three processes of adsorption, regeneration and desorption, tail gas which is rich in hydrogen and is from the adsorption towers is introduced into a first adsorption tower in a high-pressure low-temperature adsorption state for adsorption, impurities are adsorbed by an active carbon and molecular sieve combined adsorbent to purify hydrogen, high-purity hydrogen is obtained, part of hydrogen is led out from a high-purity hydrogen product and is introduced into a second adsorption tower in a regeneration state, the cold energy carried by low-temperature hydrogen is utilized to cool the second adsorption tower so as to cool and regenerate the second adsorption tower to reach the condition of re-adsorption, a third adsorption tower is in a desorption state, the hydrogen coming out of the second adsorption tower is heated to high temperature by a heating system and then is sent into the third adsorption tower for heating and desorption, the hydrogen coming out of the third adsorption tower is firstly cooled to normal temperature by a water cooler and then is sent into a second compression device and a third cooling system, and further carrying out boron removal and phosphorus removal treatment on the cooled hydrogen to separate boron and phosphorus compounds enriched in the hydrogen. The high-purity hydrogen after boron and phosphorus removal and the high-purity hydrogen from the first adsorption tower form a final high-purity hydrogen product.
The hydrogen adsorption device in the embodiment of the invention comprises three adsorption towers, wherein each adsorption tower carries out three modes of adsorption-desorption-regeneration, an adsorption process is firstly carried out, namely the adsorption tower is used as a first adsorption tower, the adsorption tower is converted into a desorption state after adsorption is finished, namely the adsorption tower is used as a third adsorption tower, temperature rising and desorption treatment is carried out, the adsorption tower is converted into a regeneration temperature reducing state after desorption is finished, namely the adsorption tower is used as a second adsorption tower, temperature reducing regeneration is carried out to meet the state of subsequent adsorption, and the adsorption tower is converted into an adsorption state after regeneration and temperature reduction, and the cycle is carried out. The recovery device for the reduction tail gas in the polysilicon production according to the second aspect of the invention is provided, wherein the leaching device 2 is a bubble column. In the embodiment of the invention, the leaching device is preferably a bubble tower, the reduction tail gas plays a role in dust removal through bubbling, fine silicon powder in the reduction tail gas can be effectively removed, the bubble tower can be optimized by adopting the existing bubble tower, 5-10 layers of tower plates are additionally arranged on the basis of the existing bubble tower according to the treatment gas amount, and the implementation is easy.
The recovery device for the reduction tail gas in the polysilicon production according to the second embodiment of the present invention, wherein the first cooling system 1 preferably comprises an air cooler, a water cooler, a gas-gas heat exchanger and a reduction tail gas chilled water cooler (not shown in the figure) connected in sequence; the second cooling system 4 comprises a primary double-effect heat exchanger, a compressed tail gas freezing water cooler, a secondary double-effect heat exchanger, a compressed tail gas cooler, a tertiary double-effect heat exchanger and a compressed tail gas deep cooler (not shown in the figure) which are connected in sequence; the lean-rich liquor heat exchange system 7 comprises a lean liquor freezing water cooler, a lean liquor cooler and a lean liquor deep cooler (not shown in the figure) which are connected in sequence. In the embodiment of the invention, each cooling system fully recovers the cold energy by arranging various cold sources which are progressive step by step, thereby greatly reducing the investment and operation cost.
The present invention is described in detail below with reference to the drawings and examples.
As shown in fig. 1, a recovery apparatus 100 for reducing tail gas in polysilicon production according to an embodiment of the present invention includes a first cooling system 1, a leaching apparatus 2, a first compression apparatus 3, a second cooling system 4, an absorption tower 5, a desorption tower 6, a lean rich solution heat exchange system 7, and a hydrogen adsorption apparatus, where the hydrogen adsorption apparatus includes a first adsorption tower 8, a second adsorption tower 9, and a third adsorption tower 11, which are connected in sequence. Wherein, a gas outlet of the first cooling system 1 is connected with a gas inlet of the leaching device 2, and a condensate outlet of the first cooling system 1 is connected with a liquid inlet of the leaching device 2; a gas outlet of the leaching device 2 is connected with a gas inlet of the first compression device 3, and a liquid outlet of the leaching device 2 is connected with a liquid inlet of the desorption tower 6; a gas inlet of the second cooling system 4 is connected with a gas outlet of the first compression device 3, and a gas outlet of the second cooling system 4 is connected with a gas inlet of the absorption tower 5; a gas outlet of the absorption tower 5 is connected with a gas inlet of the first absorption tower 8, a liquid inlet of the absorption tower 5 is connected with a barren liquor outlet of the barren and rich liquor heat exchange system 7, and a liquid outlet of the absorption tower 5 is connected with a rich liquor inlet of the barren and rich liquor heat exchange system 7; a rich solution outlet of the lean and rich solution heat exchange system 7 is connected with a liquid inlet of the desorption tower 6, and a lean solution inlet of the lean and rich solution heat exchange system 7 is connected with a liquid outlet of the desorption tower 6.
Preferably, the washing apparatus 2 is a bubble column. The first adsorption tower 8 is an empty cylinder structure with a gas distributor arranged inside, and the second adsorption tower 9 and the third adsorption tower 11 are the same as the first adsorption tower 8 in structure. Further preferably, a heating device 10 is arranged between the second adsorption tower 9 and the third adsorption tower 11, and a gas outlet of the third adsorption tower 11 is sequentially connected with a second compression device 12, a cooling system 13 after desorption and a boron and phosphorus removal device 14.
Preferably, the first cooling system 1 comprises an air cooler, a water cooler, a gas-gas heat exchanger and a reduced tail gas chilled water cooler (not shown in the figure) which are connected in sequence; the second cooling system 4 comprises a primary double-effect heat exchanger, a compressed tail gas freezing water cooler, a secondary double-effect heat exchanger, a compressed tail gas cooler, a tertiary double-effect heat exchanger and a compressed tail gas deep cooler (not shown in the figure) which are connected in sequence; the lean-rich liquor heat exchange system 7 comprises a lean liquor freezing water cooler, a lean liquor cooler and a lean liquor deep cooler (not shown in the figure) which are connected in sequence.
Example 2 recovery method of reduction tail gas in polysilicon production
In this embodiment, the recovery device of embodiment 1 is used to recover and treat the reduction tail gas in the production of polycrystalline silicon.
As shown in fig. 1, the reduction tail gas from the reduction plant is sent to a first cooling system 1, the first cooling system 1 comprises an air cooler, a water cooler, a gas-gas heat exchanger and a reduction tail gas chilled water cooler (not shown in the figure), so that the temperature of the reduction tail gas is reduced to 12-25 ℃, preferably 13 ℃, the operation cost can be effectively reduced, and the reduction tail gas passes through the first cooling system 1 and is separated to obtain the tail gas and chlorosilane condensate.
And respectively feeding the tail gas and the chlorosilane condensate obtained by separation into a leaching device 2, preferably cooling the chlorosilane condensate, preferably adopting a refrigerant at minus 35 ℃, then feeding the cooled chlorosilane condensate into the leaching device 2, and leaching and removing impurities from the tail gas in a bubble column by adopting the chlorosilane condensate, wherein in order to avoid the condensate from being generated in the subsequent compression process, the gas temperature at a gas outlet of the leaching device 2 is generally controlled to be not higher than 10 ℃, preferably at minus 5 ℃. The working pressure of the leaching device is 0.45-0.55 MPa (shown in the table).
And (3) conveying the tail gas treated by the leaching device 2 into a first compression device 3 for pressurization treatment, preferably, increasing the pressure of the tail gas to 1.1-1.5MPa (table), wherein the high pressure is favorable for reducing the overall equipment investment and the overall operation cost, and the pressurization is favorable for separating chlorosilane. The overall energy consumption is integrated, and further preferably, the inlet pressure (table) of the first compression device 3 is 0.55MPa, the outlet pressure (table) is 1.4MPa, the inlet tail gas temperature is 5 ℃, and the outlet tail gas temperature is 42 ℃. And (3) after the tail gas leaves the first compression device 3, the tail gas enters the second cooling system 4 for cooling treatment, and the temperature of the cooled tail gas is 15 ℃.
The tail gas leaving the second cooling system 4 enters an absorption tower 5, chlorosilane is used as absorption liquid in the absorption tower 5, hydrogen chloride gas in the tail gas is absorbed, chlorosilane rich liquid rich in hydrogen chloride is obtained at the bottom of the absorption tower 5, tail gas rich in hydrogen is obtained at the top of the absorption tower, the working pressure in the absorption tower 5 is 1.4MPa (table), the working temperature is-30 to-50 ℃, preferably the working temperature is-40 ℃, the hydrogen chloride absorption rate is 99%, and preferably the chlorosilane rich liquid at the bottom of the absorption tower is-35 ℃.
And (3) the chlorosilane rich solution rich in hydrogen chloride is sent into a desorption tower 6 after passing through a lean and rich solution heat exchange system 7, hydrogen chloride gas is obtained at the tower top after being treated by the desorption tower 6, and chlorosilane poor solution is obtained at the tower bottom. Preferably, the working pressure of the desorption tower 6 is 5-8 MPa (table), and more preferably 6MPa (table); the temperature of the tower system is-45-130 ℃. The tower bottom can be heated by adopting steam or high-temperature heat conducting oil, preferably, the temperature of the chlorosilane poor solution is 100-120 ℃, further preferably, the temperature of the tower kettle is 113 ℃, and hydrogen chloride gas with the mass content of more than 99% is extracted from the tower top. And (3) feeding the chlorosilane poor solution into a poor-rich solution heat exchange system 7, and feeding the chlorosilane poor solution into an absorption tower 5 to be used as an absorption solution after heat exchange with the chlorosilane rich solution. Preferably, the lean and rich liquor heat exchange system 7 uses three stages of cold sources, namely a chilled water cooler (adopting 7 ℃ chilled water), a lean liquor cooler (adopting-30 ℃ refrigerant) and a lean liquor deep cooler (adopting-55 ℃ refrigerant), and the minimum cooling temperature can reach-50 ℃. And the low-temperature chlorosilane rich solution passes through a 3-4-stage double-effect heat exchanger, is gradually and fully subjected to heat exchange with the high-temperature chlorosilane poor solution, and heat energy is recovered.
The tail gas which leaves the absorption tower 5 and is rich in hydrogen contains trace impurities, such as silicon tetrachloride, trichlorosilane, dichlorosilane, hydrogen chloride, boride, phosphide and the like, and the tail gas rich in hydrogen is sent to a hydrogen adsorption device for impurity removal treatment. The hydrogen adsorption device can set a plurality of groups according to the treatment gas amount, and each group of adsorption device comprises three adsorption towers, namely a first adsorption tower 8, a second adsorption tower 9 and a third adsorption tower 11, and can respectively perform adsorption, regeneration and desorption processes.
Preferably, the tail gas rich in hydrogen leaving the absorption tower 5 is sent to the second cooling system 4 to exchange heat with the tail gas leaving the first compression device 3, preferably, the temperature of the tail gas rich in hydrogen after heat exchange is-10 ℃ and the pressure is 1.4MPa (table), the tail gas rich in hydrogen is sent to the first absorption tower 8 in a high-pressure low-temperature absorption state to absorb impurities and further purify hydrogen, the absorbent is a combined absorbent comprising activated carbon and molecular sieve, and a high-pressure low-temperature high-purity hydrogen product can be obtained after absorption, wherein the temperature of the hydrogen is about 0 ℃ and the pressure is about 1.3MPa (table).
Part of hydrogen is led out from the high-purity hydrogen product leaving the first adsorption tower 8, preferably 3-5% of the total volume of the high-purity hydrogen product, and is sent into a second adsorption tower 9 in a medium-pressure cooling regeneration state, and the cold energy carried by low-temperature hydrogen is used for cooling the second adsorption tower 9. The temperature of the medium-pressure medium-temperature high-purity hydrogen from the second adsorption tower 9 is gradually reduced, the temperature is 180 to-10 ℃, and the pressure is 0.4 to 0.8MPa (shown in the table). The temperature of the hydrogen gas passing through the second adsorption tower 9 is also high due to the high temperature of the adsorption column at the beginning of temperature reduction, and the temperature of the hydrogen gas leaving the adsorption tower 9 is also gradually reduced as the temperature of the second adsorption tower 9 is gradually reduced.
The third adsorption tower 11 is in a low-pressure temperature-rising desorption state, the hydrogen leaving the second adsorption tower 9 is sent to a heating system 10 for heating, preferably, the temperature of the heated hydrogen is 180 ℃ and the pressure is 0.4-0.8 MPa (shown in the specification), the heated hydrogen is sent to the third adsorption tower 11, the hydrogen utilizes the heat carried by the hydrogen to heat and desorb the third adsorption tower 11, the hydrogen leaving the third adsorption tower 11 is low-pressure high-temperature low-purity hydrogen, the temperature of the hydrogen is in a state of rising all the time, the temperature is-10-180 ℃ and the pressure is 0.01-0.05 MPa (shown in the specification), and the temperature is raised along with the rising of the adsorption tower until the temperature is raised and balanced and the temperature is not changed any more.
The hydrogen leaving the third adsorption tower 11 is sent to a water cooler to be cooled to normal temperature, and then sent to a second compression device 12, and after compression, the pressure of the hydrogen reaches the pressure of the high-purity hydrogen product leaving the first adsorption tower 8. The pressurized high-pressure normal-temperature low-purity hydrogen enters the third cooling system 13. The third cooling system 13 includes a double-effect heat exchanger, a chilled water cooler, and a refrigerant cooler. The temperature of the third cooling system 13 can reach-40 to-60 ℃, so that chlorosilane in the chlorosilane is fully condensed, and after the chlorosilane is cooled by the third cooling system 13, the temperature of hydrogen leaving the third cooling system 13 is about-10 ℃.
The hydrogen leaving the third cooling system 13 is sent to a boron and phosphorus removal device 14 to further separate boron and phosphorus compounds enriched in the hydrogen to meet the requirement of boron and phosphorus content in the high-purity hydrogen product, and preferably, the boron and phosphorus removal device is filled with a molecular sieve adsorbent (commercially available, for example, from arisaema environmental protection materials limited), and after the adsorbent is saturated, the molecular sieve adsorbent can be heated at intervals to completely desorb the boron and phosphorus compounds in the adsorbent. The high-pressure low-temperature high-purity hydrogen after the boron and phosphorus compounds are separated by the boron and phosphorus removal device 14 has the temperature of about 0 ℃ and the pressure of about 1.4MPa (shown in the specification), and is merged with the high-pressure low-temperature high-purity hydrogen (0 ℃ and 1.4MPa (shown in the specification)) leaving the first adsorption tower 8 to form a final high-purity hydrogen product, wherein the purity of the hydrogen is 99%.
By the treatment of the method, the recovery rate of hydrogen chloride gas in the reduction tail gas is more than 99%, the recovery rate of chlorosilane is more than 99%, the recovery rate of hydrogen is more than 99%, and the purity of the hydrogen product is more than 99%.
Comparative example 1
The same method as that of example 2, except that the first compression device 3 is not provided, and the off gas treated by the leaching device 2 is not subjected to compression and pressurization treatment, but is directly sent to the absorption tower 5.
By adopting the method of comparative example 1, the recovery rate of chlorosilane is 85%, the recovery rate of hydrogen chloride gas is 99%, the recovery rate of hydrogen is 99%, and the purity of hydrogen product is 99%.
Compared with the method of the comparative example 1, the embodiment 2 has the advantages that the pressurization treatment is adopted to facilitate condensation of the chlorosilane, the pressure is increased, the boiling point of the gas is increased, the condensation temperature is increased, the same condensation effect can be realized by adopting a low-grade cold source, the cold source is saved, the cold consumption is reduced, the overall energy consumption is reduced by 20 percent compared with that of the comparative example 1, the recovery rate of the chlorosilane is remarkably improved, and the recovery rate of the chlorosilane is more than 99 percent.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; may be mechanically coupled, may be electrically coupled or may be in communication with each other; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.
In the present disclosure, the terms "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" and the like mean that a specific feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (10)
1. A method for recovering reduction tail gas in polycrystalline silicon production is characterized by comprising the following steps:
a. sending the reduction tail gas into a cooling system, and separating to obtain tail gas and chlorosilane condensate;
b. b, sending the tail gas obtained in the step a and the chlorosilane condensate into a leaching device, so that the chlorosilane condensate leaches the tail gas;
c. sequentially compressing and cooling the tail gas subjected to leaching treatment in the step b to obtain high-pressure tail gas;
d. c, sending the high-pressure tail gas obtained in the step c into an absorption tower, absorbing hydrogen chloride gas in the tail gas by adopting chlorosilane as absorption liquid, obtaining chlorosilane rich liquid rich in hydrogen chloride at the bottom of the absorption tower, and obtaining tail gas rich in hydrogen at the top of the absorption tower;
e. d, sending the rich chlorosilane solution rich in hydrogen chloride obtained in the step d into a desorption tower, obtaining hydrogen chloride at the top of the desorption tower, obtaining a poor chlorosilane solution at the bottom of the desorption tower, and sending the poor chlorosilane solution and the rich chlorosilane solution at the bottom of the step d into the absorption tower of the step d after heat exchange to be used as an absorption solution;
f. and d, sending the tail gas rich in hydrogen obtained in the step d into a hydrogen adsorption device to obtain hydrogen.
2. The method for recovering the reduction tail gas in the production of the polycrystalline silicon, as recited in claim 1, wherein the leaching device in the step b is a bubble column; and/or in the step b, sending the chlorosilane condensate after the tail gas is leached in the leaching device into the desorption tower in the step e to recover hydrogen chloride gas.
3. The method for recovering the reduced tail gas in the production of the polycrystalline silicon, as set forth in claim 1, wherein the hydrogen chloride extracted from the top of the desorption tower in the step e is a gas, and/or an intercooler is disposed at the upper part of the desorption tower in the step e, and water at 7 ℃ is used as a refrigerant.
4. The method for recovering the reduced tail gas in the production of polycrystalline silicon according to claim 1, wherein in the step c, the tail gas is compressed to a pressure of 1.1-1.5MPa (shown in the table).
5. The method for recovering the reduced tail gas in the production of polycrystalline silicon according to claim 1, wherein in the step c, the compressed tail gas sequentially passes through a primary double-effect heat exchanger, a compressed tail gas freezing water cooler, a secondary double-effect heat exchanger, a compressed tail gas cooler, a tertiary double-effect heat exchanger and a compressed tail gas deep cooler and then enters the absorption tower in the step d, wherein the compressed tail gas freezing water cooler adopts water at 7 ℃, the compressed tail gas cooler adopts R507 at-30 ℃, and the compressed tail gas deep cooler adopts R507 at-55 ℃.
6. The method for recovering the reduced tail gas in the production of polycrystalline silicon according to claim 5, wherein the tail gas rich in hydrogen obtained at the tower top in the step d sequentially passes through the three-stage double-effect heat exchanger, the two-stage double-effect heat exchanger and the one-stage double-effect heat exchanger to exchange heat with the tail gas compressed in the step c, and then enters the hydrogen adsorption device in the step f.
7. The method for recovering the reducing tail gas in the polysilicon production according to claim 1, wherein in the step c, the condensate generated after cooling the tail gas is mixed with the chlorosilane condensate obtained in the step a, and then the mixture is fed into the leaching device in the step b.
8. The method for recovering the reduced tail gas in the production of polycrystalline silicon according to claim 1, wherein the hydrogen adsorption device in the step f comprises a first adsorption tower, a second adsorption tower and a third adsorption tower, and the first adsorption tower, the second adsorption tower and the third adsorption tower are all hollow cylinder structures with gas distributors arranged inside; the adsorbent in the first adsorption tower is in a state with adsorption capacity, the adsorbent in the second adsorption tower is in a state needing to be regenerated, the adsorbent in the third adsorption tower is in a state needing to be desorbed, the tail gas rich in hydrogen enters the first adsorption tower for adsorption to obtain purified hydrogen, part of the purified hydrogen is sequentially sent to the second adsorption tower and the third adsorption tower, and then is subjected to compression, cooling, boron removal and phosphorus removal treatment, and then is mixed with the purified hydrogen obtained from the first adsorption tower to obtain a hydrogen product; and/or the adsorbent used in the adsorption device is a combined adsorbent comprising a molecular sieve and activated carbon.
9. A recovery device of reduction tail gas in polysilicon production is characterized by comprising a first cooling system, a leaching device, a first compression device, a second cooling system, an absorption tower, a desorption tower, a lean and rich solution heat exchange system and a hydrogen adsorption device, wherein the leaching device is a bubble tower,
a gas outlet of the first cooling system is connected with a gas inlet of the leaching device, and a condensate outlet of the first cooling system is connected with a liquid inlet of the leaching device;
a gas outlet of the leaching device is connected with a gas inlet of the first compression device, and a liquid outlet of the leaching device is connected with a liquid inlet of the desorption tower;
a gas inlet of the second cooling system is connected with a gas outlet of the first compression device, and a gas outlet of the second cooling system is connected with a gas inlet of the absorption tower;
a gas outlet of the absorption tower is connected with a gas inlet of the hydrogen adsorption device, a liquid inlet of the absorption tower is connected with a barren solution outlet of the barren and rich solution heat exchange system, and a liquid outlet of the absorption tower is connected with a rich solution inlet of the barren and rich solution heat exchange system;
and a rich solution outlet of the lean and rich solution heat exchange system is connected with a liquid inlet of the desorption tower, and a lean solution inlet of the lean and rich solution heat exchange system is connected with a liquid outlet of the desorption tower.
10. The recovery device for the reduced tail gas in the polysilicon production according to claim 9, wherein the first cooling system comprises an air cooler, a water cooler, a gas-gas heat exchanger and a reduced tail gas chilled water cooler which are connected in sequence; and/or the second cooling system comprises a primary double-effect heat exchanger, a compressed tail gas freezing water cooler, a secondary double-effect heat exchanger, a compressed tail gas cooler, a tertiary double-effect heat exchanger and a compressed tail gas deep cooler which are sequentially connected; and/or the lean-rich solution heat exchange system comprises a lean solution freezing water cooler, a lean solution cooler and a lean solution deep cooler which are connected in sequence; and/or an intercooler is arranged at the upper part of the desorption tower; and/or the hydrogen adsorption device comprises a first adsorption tower, a second adsorption tower and a third adsorption tower which are connected in sequence; and/or the hydrogen absorption device is an empty cylinder structure with a gas distributor arranged inside.
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| CN113666377A (en) * | 2021-09-30 | 2021-11-19 | 四川永祥多晶硅有限公司 | Comprehensive energy utilization method for polycrystalline silicon tail gas |
| CN115055026A (en) * | 2022-05-25 | 2022-09-16 | 云南通威高纯晶硅有限公司 | Method for purifying mixed gas by using tube array adsorption column |
| CN115414771A (en) * | 2022-08-11 | 2022-12-02 | 中国恩菲工程技术有限公司 | Tail gas treatment system and method for silicon-based electronic product production process |
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