CN105174265A - Recovery system and recovery method - Google Patents
Recovery system and recovery method Download PDFInfo
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- CN105174265A CN105174265A CN201510527559.4A CN201510527559A CN105174265A CN 105174265 A CN105174265 A CN 105174265A CN 201510527559 A CN201510527559 A CN 201510527559A CN 105174265 A CN105174265 A CN 105174265A
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Abstract
The invention provides a recovery system and a recovery method. The recovery system comprises a condensing unit and an adsorption/desorption unit; a non-condensable gas and a condensed liquid are obtained after a reducing tail gas passes through the condensing unit, and the outlet of the condensing unit is connected with a non-condensable gas output pipe and a condensed liquid output pipe; the adsorption/desorption unit is connected with the non-condensable gas output pipe, and is used to separated hydrogen from the non-condensable gas; a desorption gas is obtained after the non-condensable gas passes the adsorption/desorption unit and is subjected to adsorption and desorption; the outlet of the adsorption/desorption unit is connected with the hydrogen output pipe and the desorption gas output pipe, the hydrogen output pipe is connected with an inlet of a polysilicon reduction system, and the desorption gas output pipe is connected with an inlet of a silicon tetrachloride hydrogenation system. The above recovery system avoids frequent heating and cooling of a liquid chlorosilane material, reduces consumption of cold quantity and heat in a drying-process recovery system, avoids cold quantity waste generated when hydrogen chloride in the non-condensable gas returns to the recovery system, and also avoids impurity enrichment.
Description
Technical field
The present invention relates to technical field prepared by polysilicon, in particular to a kind of recovery system and recovery method.
Background technology
Polysilicon process is produced in the hydrogen reduction of improved Siemens trichlorosilane, reaction conversion ratio is about 10%, unreacted hydrogen, trichlorosilane and byproduct of reaction silicon tetrachloride, hydrogenchloride, dichlorosilane form reduction tail gas jointly, enter Dry recovery systematic position, recovery.Traditional Dry recovery system is made up of " condensation separation chlorosilane-absorption desorption separating hydrogen chloride-adsorption cleaning reclaims hydrogen " three parts.Concrete technology is for reducing tail gas elder generation through pressurization condensation with recovering liquid chlorosilane, again by the hydrogenchloride of the overwhelming majority in the mode Separation and Recovery non-condensable gas of low temperature chlorosilane absorption-high temperature desorption, after through the chlorosilane of charcoal absorption wherein minute quantity, hydrogenchloride and other impurity, the overwhelming majority after absorption reclaims hydrogen and turns back to hydrogenation of silicon tetrachloride system, the recovery hydrogen of small part as blowback air by the chlorosilane of charcoal absorption and hydrogenchloride desorption, after desorption, mixed gas is back to the condensation procedure of Dry recovery system, isolated hydrogenchloride is delivered to hydrogenation of silicon tetrachloride system and is participated in reaction.
But in the production of actual polysilicon, hydrogenchloride a large amount of in reduction tail gas is soluble in the chlorosilane lime set of cryogenic condensation, the chlorination hydrogen amount of such Dry recovery system recoveries is little, and also create frequent cooling and the intensification of liquid chlorosilanes material, thus cause hot and cold amount consumption all very large for this reason.Simultaneously, except containing except chlorosilane and hydrogenchloride in the desorption gas of desorption adsorption column, the impurity such as boron, phosphorus, nitrogen, oxygen, carbon also containing trace, after desorption, gas returns dry method system, impurity is circulation collection in hydrogen always, thus also affects the quality of product high purity polycrystalline silicon.
Summary of the invention
Main purpose of the present invention is to provide a kind of recovery system and recovery method, to improve purity and the quality of the polysilicon produced.
To achieve these goals, according to an aspect of the present invention, provide a kind of recovery system, for reclaiming the reduction tail gas that polycrystalline silicon reduction system produces, polycrystalline silicon reduction system and hydrogenation of silicon tetrachloride system connectivity, it is characterized in that, recovery system comprises: condensing unit, reduction tail gas is by obtaining noncondensable gas and condensed liquid after condensing unit, and the outlet of condensing unit is connected with noncondensable gas output channel and condensed liquid output channel; Adsorption desorption unit, be connected with noncondensable gas output channel, adsorption desorption unit is used for by the Hydrogen Separation in noncondensable gas out, noncondensable gas is by obtaining desorption gas after adsorption desorption unit generation adsorption and desorption, and the outlet of adsorption desorption unit is connected with hydrogen output channel and desorption gas output channel, and hydrogen output channel is connected to the entrance of polycrystalline silicon reduction system, desorption gas output channel is connected to the entrance of hydrogenation of silicon tetrachloride system.
Further, recovery system also comprises: desorption unit, is connected with condensed liquid output channel, and condensed liquid comprises gas after the desorption of hydrogenchloride by obtaining component after desorption unit; Tail gas treating unit, is connected to the outlet of desorption unit, for carrying out condensation to gas after desorption and purifying with tail gas after the condensation obtaining comprising hydrogenchloride; Crystalline element, be connected to the outlet of tail gas treating unit, comprise neutralizing well and evaporation unit, the hydrogenchloride after condensation in tail gas and the alkaline reaction in neutralizing well generate chloride soln, and chloride soln obtains chloride crystallization body after being evaporated by evaporation unit.
Further, desorption unit comprises low pressure chlorosilane basin and/or chlorosilane separating-purifying tower.
Further, reduction tail gas comprises hydrogen, hydrogenchloride, chlorosilane and boron and phosphorus matter, and desorption gas comprises hydrogenchloride, chlorosilane and boron and phosphorus matter.
According to a further aspect in the invention, provide a kind of recovery method, the recovery system any one of claim 1 to 4 is utilized to reclaim the reduction tail gas of polycrystalline silicon reduction system generation, polycrystalline silicon reduction system and hydrogenation of silicon tetrachloride system connectivity, recovery method comprises: step S1, reduction tail gas is passed into condensing unit in recovery system, obtains noncondensable gas and condensed liquid; Step S2, by noncondensable gas, the adsorption desorption unit passed in recovery system carries out adsorption desorption process, and with by the Hydrogen Separation in noncondensable gas out, and noncondensable gas obtains desorption gas after carrying out adsorption treatment and desorption process by adsorption desorption unit; Step S3, the hydrogen separated by adsorption desorption unit to be passed in polycrystalline silicon reduction system, and desorption gas is passed in hydrogenation of silicon tetrachloride system.
Further, recovery system is the recovery system of claim 2; Recovery method also comprises: step S4, be passed in desorption unit by condensed liquid, obtains component and comprises gas after the desorption of hydrogenchloride; Step S5, gas after desorption passed in tail gas treating unit and carries out condensation process with tail gas after the condensation obtaining comprising hydrogenchloride; Step S6, pass in neutralizing well by tail gas after condensation, the hydrogenchloride after making condensation in tail gas and the alkaline reaction in neutralizing well generate chloride soln, and reclaim the supernatant liquor of neutralizing well, are made the chloride crystallization in supernatant liquor by evaporation unit.
Further, recovery system is the recovery system of claim 3; After obtaining desorption, the step of gas comprises: condensed liquid is passed into low pressure chlorosilane basin, to isolate gas after desorption from condensed liquid; And/or condensed liquid is passed into chlorosilane separating-purifying tower purify, gas after desorption is formed on purification tower top.
Further, in step sl, by carrying out low pressure condensation process and high pressure condensation process to reduction tail gas, noncondensable gas and condensed liquid is obtained; In step s3, after pressure treatment is carried out to desorption gas, pass in hydrogenation of silicon tetrachloride system.
Further, in step sl, the gauge pressure of low pressure condensation process is 0.4 ~ 0.6MPaG, low pressure condensation treatment temp be-5 ~-30 DEG C, the gauge pressure of high pressure condensation process is 1.0 ~ 1.2MPaG, and the temperature of high pressure condensation process is-45 ~-35 DEG C; In step s 2, the gauge pressure of adsorption treatment is 1.0 ~ 1.2MPaG, and the temperature of adsorption treatment is 15 ~ 40 DEG C, and the gauge pressure of desorption process is 0.03 ~ 0.06MPaG, and the temperature of desorption process is 100 ~ 130 DEG C; In step s3, the gauge pressure of pressure treatment is 1.9 ~ 3.0MPaG.
Further, in step s 5, the gauge pressure of condensation process is 0.3 ~ 0.6MPaG, and the temperature of condensation process is-15 ~-30 DEG C; In step s 6, alkali lye to be mass concentration be 5 ~ 25% calcium hydroxide.
Apply technical scheme of the present invention, the invention provides a kind of recovery system, this recovery system comprises condensing unit and adsorption desorption unit, because adsorption desorption unit is connected by noncondensable gas output channel with condensing unit, adsorption desorption unit is connected with polycrystalline silicon reduction system by hydrogen output channel, and adsorption desorption unit is also connected with hydrogenation of silicon tetrachloride system by desorption gas output channel, thus eliminate the operation of hydrogenchloride low temperature absorption-high temperature desorption in the Dry recovery system of prior art, avoid the frequent liter of liquid chlorosilane material, cooling, reduce in Dry recovery system cold, the consumption of heat, and, because the hydrogenchloride in the non-condensable gas that condensing unit produces to be present in desorption gas and to enter hydrogenation of silicon tetrachloride system, thus avoid its condensing unit waste cold returning recovery system, it also avoid the closed cycle of reduction tail gas between polycrystalline silicon reduction system and recovery system and the impurity enriched that causes simultaneously, and then improve purity and the quality of the polysilicon produced.
Accompanying drawing explanation
The Figure of description forming a application's part is used to provide a further understanding of the present invention, and schematic description and description of the present invention, for explaining the present invention, does not form inappropriate limitation of the present invention.In the accompanying drawings:
Fig. 1 shows the recovery system that embodiment of the present invention provides, and recovery system is connected with the schematic diagram of polycrystalline silicon reduction system and hydrogenation of silicon tetrachloride system; And
Fig. 2 shows the schematic flow sheet of the recovery method that embodiment of the present invention provides.
Embodiment
It should be noted that, when not conflicting, the embodiment in the application and the feature in embodiment can combine mutually.Below with reference to the accompanying drawings and describe the present invention in detail in conjunction with the embodiments.
It should be noted that used term is only to describe embodiment here, and be not intended to restricted root according to illustrative embodiments of the present invention.As used herein, unless the context clearly indicates otherwise, otherwise singulative is also intended to comprise plural form, in addition, it is to be further understood that, " comprise " when using term in this manual and/or " comprising " time, it indicates existing characteristics, step, operation, device, assembly and/or their combination.
For convenience of description, here can usage space relative terms, as " ... on ", " in ... top ", " at ... upper surface ", " above " etc., be used for the spatial relation described as a device shown in the figure or feature and other devices or feature.Should be understood that, space relative terms is intended to comprise the different azimuth in use or operation except the described in the drawings orientation of device.Such as, " in other devices or structure below " or " under other devices or structure " will be positioned as after if the device in accompanying drawing is squeezed, being then described as the device of " above other devices or structure " or " on other devices or structure ".Thus, exemplary term " in ... top " can comprise " in ... top " and " in ... below " two kinds of orientation.This device also can other different modes location (90-degree rotation or be in other orientation), and relatively describe space used here and make respective explanations.
As what introduce in background technology, in the production of actual polysilicon, the chlorination hydrogen amount of Dry recovery system recoveries is little, and hot and cold amount consumption is all very large, and the impurity circulation collection in hydrogen always in desorption gas, thus also affect the quality of product high purity polycrystalline silicon.The present inventor studies for the problems referred to above, propose a kind of recovery system, for reclaiming the reduction tail gas that polycrystalline silicon reduction system 30 produces, polycrystalline silicon reduction system 30 is communicated with hydrogenation of silicon tetrachloride system 20, its structure as shown in Figure 1, this recovery system 10 comprises: condensing unit 110, and reduction tail gas is by obtaining noncondensable gas and condensed liquid after condensing unit 110, and the outlet of condensing unit 110 is connected with noncondensable gas output channel and condensed liquid output channel; Adsorption desorption unit 120, be connected with noncondensable gas output channel, adsorption desorption unit 120 is for by the Hydrogen Separation in noncondensable gas out, noncondensable gas obtains desorption gas after there is adsorption and desorption by adsorption desorption unit 120, and the outlet of adsorption desorption unit 120 is connected with hydrogen output channel 122 and desorption gas output channel 121, and hydrogen output channel 122 is connected to the entrance of polycrystalline silicon reduction system 30, desorption gas output channel 121 is connected to the entrance of hydrogenation of silicon tetrachloride system 20.
Because adsorption desorption unit is connected by noncondensable gas output channel with condensing unit in above-mentioned recovery system, adsorption desorption unit is connected with polycrystalline silicon reduction system by hydrogen output channel, and adsorption desorption unit is also connected with hydrogenation of silicon tetrachloride system by desorption gas output channel, thus eliminate the operation of hydrogenchloride low temperature absorption-high temperature desorption in the Dry recovery system of prior art, avoid the frequent heating-cooling of liquid chlorosilane material, reduce the consumption of hot and cold amount in Dry recovery system; And, because the hydrogenchloride in the non-condensable gas that condensing unit produces to be present in desorption gas and to enter hydrogenation of silicon tetrachloride system, thus avoid its condensing unit waste cold returning recovery system, it also avoid the closed cycle of reduction tail gas between polycrystalline silicon reduction system and recovery system and the impurity enriched that causes simultaneously, and then improve purity and the quality of the polysilicon produced.
Above-mentioned condensed liquid comprises liquid chlorosilane and is dissolved in the hydrogenchloride of liquid chlorosilane; Above-mentioned noncondensable gas comprises the impurity such as hydrogen and hydrogenchloride, chlorosilane and boron phosphorus, and above-mentioned noncondensable gas is obtained pure recover hydrogen by after the adsorbent in adsorption desorption unit 120, major part recover hydrogen is back to polycrystalline silicon reduction system 30, small part recover hydrogen is used for pulse cleaning sorbent material, with by desorptions such as adsorbent hydrogenchloride, chlorosilane and boron and phosphorus matter, to form above-mentioned desorption gas.
State on the invention in recovery system, recovery system 10 can also comprise: desorption unit 130, is connected with condensed liquid output channel, and condensed liquid comprises gas after the desorption of hydrogenchloride by obtaining component after desorption unit 130; Tail gas treating unit 140, is connected to the outlet of desorption unit 130, for carrying out condensation to gas after desorption to reclaim chlorosilane liquid produced, obtains tail gas after the condensation of containing hydrogen chloride; Crystalline element 150, is connected to the outlet of tail gas treating unit 140, comprises neutralizing well and evaporation unit, and the alkaline reaction in hydrogen chloride gas and neutralizing well generates chloride soln, and chloride soln obtains chloride crystallization body after being evaporated by evaporation unit.
In above-mentioned preferably embodiment, because condensing unit 110 is also connected with desorption unit 130 in turn, tail gas treating unit 140 and crystalline element 150, thus to make the condensed liquid by obtaining after condensing unit 110 obtain component by desorption unit 130 be gas after the desorption of hydrogenchloride, and by gas after desorption by tail gas treating unit 140, condensation is carried out to gas after desorption and purifies with tail gas after the condensation obtaining comprising hydrogenchloride, tail gas after condensation is passed into crystalline element 150, the hydrogenchloride in tail gas after condensation is carried out neutralization reaction and evaporative crystallization obtains chloride crystallization product, above-mentioned chloride crystallization product can be sold as outside Chemicals.After above-mentioned desorption, gas also comprises nitrogen, hydrogen and chlorosilane except comprising hydrogenchloride, and wherein hydrogenchloride accounts for 5 ~ 15% of gas volume total amount after desorption.
State on the invention in recovery system, kind and the composition of desorption unit 130 can set according to prior art, and preferably, desorption unit 130 comprises low pressure chlorosilane basin 131 and/or chlorosilane separating-purifying tower 132.Obtain during 10 condensation of Dry recovery system condensed liquid (comprise liquid chlorosilane and be dissolved in the hydrogenchloride of a liquid chlorosilane) part with desorption in nitrogen-sealed low pressure chlorosilane basin 131 out hydrogenchloride enter tail gas treating unit 140, another part enters purification system, and at chlorosilane separating-purifying tower 132 top, hydrogenchloride enters tail gas treating unit 140 with the form of non-condensable gases.
State on the invention in recovery system, in hydrogenation of silicon tetrachloride system 20, trichlorosilane hydrogen reduction produces the reaction conversion ratio of polysilicon process about 10%, the reduction tail gas that the reduction tail gas passing into recovery system 10 can produce for above-mentioned hydrogenation of silicon tetrachloride system 20, comprise unreacted hydrogen, trichlorosilane and byproduct of reaction silicon tetrachloride, hydrogenchloride, dichlorosilane and and boron and phosphorus matter etc.; Obtain desorption gas after there is adsorption and desorption by adsorption desorption unit 120 and can comprise hydrogenchloride and chlorosilane, further, desorption gas can also comprise a small amount of hydrogen.Above-mentioned desorption gas enters hydrogenation of silicon tetrachloride system 20 by attached gas outlet duct, reaches the effect of hydrogenchloride cycling and reutilization, avoids its condensing unit 110 returning recovery system 10 simultaneously and wastes cold.
According to a further aspect in the invention, provide a kind of recovery method, as shown in Figure 2, this recovery method utilizes the recovery system any one of claim 1 to 4 to reclaim the reduction tail gas of polycrystalline silicon producing device generation, polycrystalline silicon reduction system and hydrogenation of silicon tetrachloride system connectivity, and this recovery method comprises: step S1, reduction tail gas is passed into condensing unit in recovery system, obtain noncondensable gas and condensed liquid; Step S2, by noncondensable gas, the adsorption desorption unit passed in recovery system carries out adsorption desorption process, and with by the Hydrogen Separation in noncondensable gas out, and noncondensable gas obtains desorption gas after carrying out adsorption treatment and desorption process by adsorption desorption unit; Step S3, the hydrogen separated by adsorption desorption unit to be passed in polycrystalline silicon reduction system, and desorption gas is passed in hydrogenation of silicon tetrachloride system.
Because above-mentioned recovery method make use of the above-mentioned recovery system of the present invention, and adsorption desorption unit is connected by noncondensable gas output channel with condensing unit in this recovery system, adsorption desorption unit is connected with polycrystalline silicon reduction system by hydrogen output channel, and adsorption desorption unit is also connected with hydrogenation of silicon tetrachloride system by desorption gas output channel, thus eliminate the operation of hydrogenchloride low temperature absorption-high temperature desorption in the Dry recovery system of prior art, avoid the frequent heating-cooling of liquid chlorosilane material, reduce the consumption of hot and cold amount in Dry recovery system; And, because the hydrogenchloride in the non-condensable gas that condensing unit produces to be present in desorption gas and to enter hydrogenation of silicon tetrachloride system, thus avoid its condensing unit waste cold returning recovery system, it also avoid the closed cycle of reduction tail gas between polycrystalline silicon reduction system and recovery system and the impurity enriched that causes simultaneously, and then improve purity and the quality of the polysilicon produced.
The illustrative embodiments of the recovery method provided according to the application will be described in more detail below.But these illustrative embodiments can be implemented by multiple different form, and should not be interpreted as being only limited to embodiment set forth herein.Should be understood that, provide these embodiments be in order to make the application open thorough and complete, and the design of these illustrative embodiments is fully conveyed to those of ordinary skill in the art.
Utilize above-mentioned recovery system to reclaim the reduction tail gas of polycrystalline silicon producing device generation, polycrystalline silicon producing device comprises hydrogenation of silicon tetrachloride system and polycrystalline silicon reduction system.First, reduction tail gas is passed into the condensing unit in recovery system, obtain noncondensable gas and condensed liquid.More preferably, in above-mentioned steps, by carrying out low pressure condensation process and high pressure condensation process to reduction tail gas, obtain noncondensable gas and condensed liquid.Low pressure condensation process refers to and passes in the environment compared with low pressure and lesser temps by reduction tail gas, and high pressure condensation process then refers to and passed in the environment of higher pressure and lesser temps by reduction tail gas.
Above-mentioned preferred embodiment in, the gauge pressure of low pressure condensation process can be 0.4 ~ 0.6MPaG, low pressure condensation treatment temp can be-5 ~-30 DEG C; The gauge pressure of high pressure condensation process can be 1.0 ~ 1.2MPaG, and the temperature of high pressure condensation process can be-45 ~-35 DEG C.In above-mentioned preferred parameter area, the reduction tail gas including trichlorosilane and silicon tetrachloride passing into condensing unit can be made to be liquefied to form condensed liquid more rapidly and fully, thus the more efficiently recovery carrying out liquid chlorosilane, also can will carry out adsorption desorption process effectively simultaneously.
Reduction tail gas is passed into condensing unit in recovery system completing, after obtaining the step of noncondensable gas and condensed liquid, the adsorption desorption unit passed into by noncondensable gas in recovery system carries out adsorption desorption process, with by the Hydrogen Separation in noncondensable gas out, and noncondensable gas is by obtaining desorption gas after adsorption desorption unit generation adsorption and desorption.In above-mentioned steps, the reduction tail gas including hydrogen, hydrogenchloride and dichlorosilane be not liquefied forms noncondensable gas, this noncondensable gas is passed in adsorption desorption unit and carries out adsorption treatment, wherein noncondensable gas is in addition to hydrogen tightly held by activated carbon post absorption, thus from noncondensable gas by Hydrogen Separation out, desorption process is carried out to the noncondensable gas being tightly held by activated carbon post absorption, thus forms the desorption gas including the noncondensable gas being tightly held by activated carbon post absorption.
In a preferred embodiment, adsorption treatment can be 1.0 ~ 1.2MPaG in gauge pressure, and temperature is carry out under the condition of 15 ~ 40 DEG C; Desorption process can be 0.03 ~ 0.06MPaG in gauge pressure, and temperature is carry out at 100 ~ 130 DEG C.In above-mentioned preferred parameter area, from the noncondensable gas be passed into adsorption desorption unit, hydrogen can be isolated more rapidly and fully, thus more efficientlyly can carry out desorption process to form desorption gas to active carbon adsorption column absorption.
Carry out adsorption desorption process completing the adsorption desorption unit passed in recovery system by noncondensable gas, with by the Hydrogen Separation in noncondensable gas out, and after noncondensable gas obtains the step of desorption gas after carrying out adsorption treatment and desorption process by adsorption desorption unit, the hydrogen separated by adsorption desorption unit is passed in polycrystalline silicon reduction system, and desorption gas is passed in hydrogenation of silicon tetrachloride system.In above-mentioned steps, the step passed into by the hydrogen separated by adsorption desorption unit in polycrystalline silicon reduction system can carry out effective recycling to the hydrogen in reduction tail gas, continue on for producing in the operation of polysilicon by the hydrogen in the reduction tail gas that polycrystalline silicon producing device produces, on the other hand, the desorption gas that the step passed into by desorption gas in hydrogenation of silicon tetrachloride system can include hydrogen, hydrogenchloride and chlorosilane participates in hydrogenation of silicon tetrachloride as reactant and generates in the technique of trichlorosilane.
Desorption gas is being passed in the step of hydrogenation of silicon tetrachloride system, after first can carrying out pressure treatment to desorption gas, then passing in hydrogenation of silicon tetrachloride system.Pressure treatment can make that desorption gas is more efficiently is passed into the generating process participating in trichlorosilane in hydrogenation of silicon tetrachloride system.Above-mentioned pressure treatment can be carried out under gauge pressure is the processing condition of 1.9 ~ 3.0MPaG.In above-mentioned preferred parameter area, more desorption gas can be made to be passed into the generating process participating in trichlorosilane in hydrogenation of silicon tetrachloride system more rapidly.
Apply for that the step of the recovery method provided is not limited in above-mentioned embodiment.Preferably, the step of recovery method can also comprise: step S4, be passed in desorption unit by condensed liquid, obtains component and comprises gas after the desorption of hydrogenchloride; Step S5, gas after desorption passed in tail gas treating unit and carries out condensation process with tail gas after the condensation obtaining comprising hydrogenchloride; Step S6, pass in neutralizing well by tail gas after above-mentioned condensation, the hydrogenchloride after making condensation in tail gas and the alkaline reaction in neutralizing well generate chloride soln, and reclaim the supernatant liquor of neutralizing well, are made the chloride crystallization in supernatant liquor by evaporation unit.By carrying out the process of above-mentioned steps to condensed liquid, the hydrogenchloride in condensed liquid can be made to form chloride crystallization product, to sell as product.Wherein, the alkali lye in neutralizing well can be calcium hydroxide, more preferably, the mass concentration of calcium hydroxide is 5 ~ 25%, and now neutralization generates calcium chloride, finally reclaims the supernatant liquor of neutralizing well, make Chlorine in Solution crystalline solvate by evaporation, sell as outside Chemicals.After above-mentioned desorption, gas also comprises nitrogen, hydrogen and chlorosilane except comprising hydrogenchloride, and wherein hydrogenchloride accounts for 5 ~ 15% of gas volume total amount after desorption.
Above-mentioned preferred embodiment in, after obtaining desorption, the step of gas can comprise: condensed liquid is passed into low pressure chlorosilane basin, to isolate gas after described desorption from condensed liquid; And/or condensed liquid is passed into chlorosilane separating-purifying tower carry out purification & isolation chlorosilane, gas after desorption is formed on purification tower top.In above-mentioned steps, the hydrogenchloride being dissolved in liquid chlorosilane in condensed liquid can be divided into two portions, in the low pressure chlorosilane basin of a part in desorption unit, desorption out enters tail gas treating unit, another part enters the chlorosilane separating-purifying tower of desorption unit with chlorosilane material, enters tail gas treating unit at purification tower top with the form of non-condensable gases; Through condensation with purify to reclaim the chlorosilane in condensed liquid in tail gas treating unit, enter neutralizing well in crystalline element and alkali lye afterwards again and carry out neutralization reaction and generate muriate.
Above-mentioned by desorption after gas pass in tail gas treating unit carry out condensation process with the condensation obtaining comprising hydrogenchloride after tail gas step in, the gauge pressure of condensation process can be 0.3 ~ 0.6MPaG, the temperature of condensation process can be-15 ~-30 DEG C, chlorosilane after above-mentioned preferred parameter area can make desorption in gas is reclaimed more rapidly and fully, thus recovery chlorosilane liquid produced, and then tail gas after the condensation of containing hydrogen chloride is passed in neutralizing well effectively generates muriate.
As can be seen from the above description, the above embodiments of the present invention achieve following technique effect:
1, because adsorption desorption unit is connected by noncondensable gas output channel with condensing unit, thus eliminate the operation of hydrogenchloride low temperature absorption-high temperature desorption in the Dry recovery system of prior art, avoid the frequent heating-cooling of liquid chlorosilane material, reduce the consumption of hot and cold amount in Dry recovery system;
2, because adsorption desorption unit is connected with polycrystalline silicon reduction system by hydrogen output channel, condensing unit produce non-condensable gas in hydrogenchloride to be present in desorption gas and to enter hydrogenation of silicon tetrachloride system, thus avoid its condensing unit waste cold returning recovery system, it also avoid the closed cycle of reduction tail gas between polycrystalline silicon reduction system and recovery system and the impurity enriched that causes simultaneously, and then improve purity and the quality of the polysilicon produced;
3, because adsorption desorption unit is connected with hydrogenation of silicon tetrachloride system by desorption gas output channel, and condensed liquid output channel is connected with desorption unit, tail gas treating unit and crystalline element in turn, thus the hydrogenchloride be dissolved in condensed liquid is reclaimed by the form being converted into chloride crystals, also significantly reduce chloride ion content in efflux wastewater simultaneously, and then make the byproduct hydrogen chloride of polycrystalline silicon reduction system obtain comprehensive recovery, utilization, avoid the loss of hydrogenchloride material, there is good economy and environmental benefit.
These are only the preferred embodiments of the present invention, be not limited to the present invention, for a person skilled in the art, the present invention can have various modifications and variations.Within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (10)
1. a recovery system, for reclaiming the reduction tail gas that polycrystalline silicon reduction system (30) produces, described polycrystalline silicon reduction system (30) is communicated with hydrogenation of silicon tetrachloride system (20), it is characterized in that, described recovery system (10) comprising:
Condensing unit (110), described reduction tail gas obtains noncondensable gas and condensed liquid by after described condensing unit (110), and the outlet of described condensing unit (110) is connected with noncondensable gas output channel and condensed liquid output channel;
Adsorption desorption unit (120), be connected with described noncondensable gas output channel, described adsorption desorption unit (120) is for by the Hydrogen Separation in described noncondensable gas out, described noncondensable gas obtains desorption gas after there is adsorption and desorption by described adsorption desorption unit (120), and the outlet of described adsorption desorption unit (120) is connected with hydrogen output channel (122) and desorption gas output channel (121), and described hydrogen output channel (122) is connected to the entrance of described polycrystalline silicon reduction system (30), described desorption gas output channel (121) is connected to the entrance of described hydrogenation of silicon tetrachloride system (20).
2. recovery system according to claim 1, is characterized in that, described recovery system (10) also comprises:
Desorption unit (130), is connected with described condensed liquid output channel, and described condensed liquid comprises gas after the desorption of hydrogenchloride by obtaining component after described desorption unit (130);
Tail gas treating unit (140), is connected to the outlet of described desorption unit (130), for carrying out condensation to gas after described desorption and purifying with tail gas after the condensation obtaining comprising hydrogenchloride;
Crystalline element (150), be connected to the outlet of described tail gas treating unit (140), comprise neutralizing well and evaporation unit, alkaline reaction in hydrogenchloride after described condensation in tail gas and described neutralizing well generates chloride soln, and described chloride soln obtains chloride crystallization body after being evaporated by evaporation unit.
3. recovery system according to claim 2, is characterized in that, described desorption unit (130) comprises low pressure chlorosilane basin (131) and/or chlorosilane separating-purifying tower (132).
4. recovery system according to claim 1, is characterized in that, described reduction tail gas comprises hydrogen, hydrogenchloride, chlorosilane and boron and phosphorus matter, and described desorption gas comprises hydrogenchloride, chlorosilane and boron and phosphorus matter.
5. a recovery method, it is characterized in that, utilize the reduction tail gas that the recovery system according to any one of claim 1 to 4 (10) recovery polycrystalline silicon reduction system (30) produces, described polycrystalline silicon reduction system (30) is communicated with hydrogenation of silicon tetrachloride system (20), and described recovery method comprises:
Step S1, the condensing unit (110) passed into by described reduction tail gas in described recovery system (10), obtain noncondensable gas and condensed liquid;
Step S2, by described noncondensable gas, the adsorption desorption unit (120) passed in described recovery system (10) carries out adsorption desorption process, with by the Hydrogen Separation in described noncondensable gas out, and described noncondensable gas obtains desorption gas after carrying out adsorption treatment and desorption process by described adsorption desorption unit (120);
Step S3, the hydrogen separated by described adsorption desorption unit (120) to be passed in described polycrystalline silicon reduction system (30), and described desorption gas is passed in described hydrogenation of silicon tetrachloride system (20).
6. recovery method according to claim 5, is characterized in that,
Described recovery system (10) is recovery system according to claim 2 (10);
Described recovery method also comprises:
Step S4, described condensed liquid to be passed in described desorption unit (130), to obtain component and comprise gas after the desorption of hydrogenchloride;
Step S5, gas after described desorption passed in described tail gas treating unit (140) and carries out condensation process with tail gas after the condensation obtaining comprising hydrogenchloride;
Step S6, tail gas after described condensation is passed in described neutralizing well, hydrogenchloride after making described condensation in tail gas and the alkaline reaction in described neutralizing well generate chloride soln, and reclaim the supernatant liquor of described neutralizing well, the chloride crystallization in supernatant liquor is made by described evaporation unit.
7. recovery method according to claim 6, is characterized in that,
Described recovery system (10) is recovery system according to claim 3 (10);
After obtaining described desorption, the step of gas comprises:
Described condensed liquid is passed into described low pressure chlorosilane basin (131), to isolate gas after described desorption from described condensed liquid; And/or
Described condensed liquid is passed into described chlorosilane separating-purifying tower (132) to purify, gas after described desorption is formed on described purification tower (132) top.
8. recovery method according to claim 5, is characterized in that,
In described step S1, by carrying out low pressure condensation process and high pressure condensation process to described reduction tail gas, obtain described noncondensable gas and described condensed liquid;
In described step S3, after pressure treatment is carried out to described desorption gas, pass in described hydrogenation of silicon tetrachloride system (20).
9. recovery method according to claim 8, is characterized in that,
In described step S1, the gauge pressure of described low pressure condensation process is 0.4 ~ 0.6MPaG, and described low pressure condensation treatment temp is-5 ~-30 DEG C, and the gauge pressure of described high pressure condensation process is 1.0 ~ 1.2MPaG, and the temperature of described high pressure condensation process is-45 ~-35 DEG C;
In described step S2, the gauge pressure of described adsorption treatment is 1.0 ~ 1.2MPaG, and the temperature of described adsorption treatment is 15 ~ 40 DEG C, and the gauge pressure of described desorption process is 0.03 ~ 0.06MPaG, and the temperature of described desorption process is 100 ~ 130 DEG C;
In described step S3, the gauge pressure of described pressure treatment is 1.9 ~ 3.0MPaG.
10. recovery method according to claim 6, is characterized in that,
In described step S5, the gauge pressure of described condensation process is 0.3 ~ 0.6MPaG, and the temperature of described condensation process is-15 ~-30 DEG C;
In described step S6, described alkali lye to be mass concentration be 5 ~ 25% calcium hydroxide.
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