CN103523752A

CN103523752A - Process for purifying hydrogen obtained by recycling reductive transformation exhaust gas during production of polycrystalline silicon

Info

Publication number: CN103523752A
Application number: CN201210226544.0A
Authority: CN
Inventors: 王航舟; 陈自力; 孙晓龙; 唐伟博; 秦西鸣
Original assignee: Shaanxi Tianhong Silicon Material Co Ltd
Current assignee: Shaanxi Tianhong Silicon Material Co Ltd
Priority date: 2012-07-03
Filing date: 2012-07-03
Publication date: 2014-01-22

Abstract

The invention relates to a process for purifying hydrogen obtained by recycling reductive transformation exhaust gas during production of polycrystalline silicon. The flow chart is as shown by an attached drawing 1 in the specification. According to the process, hydrogen obtained by recycling reductive transformation exhaust gas during the production of polycrystalline silicon is passed through a variable temperature adsorber in which silica gel and active carbon are used as adsorbents at 15 bar and 25-30 DEG C to remove a trace of HCl and chlorosilane in recovered hydrogen; then hydrogen is passed through a variable pressure adsorber in which a molecular sieve is used as an adsorbent to reduce methane and nitrogen in the recovered hydrogen, wherein in the whole technical process, the nitrogen content can be reduced to be less than 100ppmv and the methane content can be reduced to be less than 50ppmv; finally, hydrogen is delivered to a gas consuming working section through filtration buffering. Through the technical process of the process disclosed by the invention, the contents of methane and nitrogen which can not be removed by the original device in hydrogen obtained by recycling the reductive transformation exhaust gas during the production of polycrystalline silicon are reduced, the input cost is low, and the running cost is relatively low, so that the process is suitable for industrial large-scale production.

Description

In production of polysilicon, reduction transforms the purifying process of tail gas recycle gained hydrogen

One, technical field

The present invention relates to the purifying process of reduction conversion tail gas recycle gained recover hydrogen in production of polysilicon, it belongs to the purifying process of reduction conversion tail gas recycle gained recover hydrogen in production of polysilicon.This technique is that reduction furnace, converter tail gas in polysilicon production process are reclaimed to gained recover hydrogen purifying in tail gas recycle workshop section, reduces methane, a nitrogen content in recover hydrogen, improves the quality of recover hydrogen, thereby promotes the quality of polysilicon finished product.

Two, background technology

Along with the develop rapidly of polysilicon industry, the continuous expansion of scale, output, specification of quality improves constantly.Improve the quality of products, the competitive power of enterprise in market becomes polysilicon enterprise inevitable choice.

Polysilicon industry adopts following technique to the recover hydrogen purifying of gained in production process both at home and abroad at present:

(1) cryogenic absorption technique: the recover hydrogen in production process is adopted to low temperature active charcoal adsorption unit, adsorb methane, a nitrogen content of reducing in recover hydrogen.

(2) membrane separation process: the recover hydrogen in production process, by special palladium film, is carried out to separation and effectively intercepted impurity, thereby improve the quality of recover hydrogen.

Above-mentioned two kinds of methods, reduce methane, the nitrogen in recover hydrogen although can realize recover hydrogen purifying, and above-mentioned two kinds of process unit costs of investment are very high, and running cost is quite high, complex process, has virtually increased product cost.

Along with the development at home of polysilicon industry, the polysilicon of producing low-cost and high-quality has become the emphasis of competition

Three, summary of the invention

The purifying process that the object of this invention is to provide reduction conversion tail gas recycle gained recover hydrogen in a kind of production of polysilicon, by the Temp .-changing adsorption device that in polysilicon production process, recover hydrogen process silica gel and gac are sorbent material, remove HCL, the chlorosilane of trace in recover hydrogen, and then reduce methane, the nitrogen in recover hydrogen through take the pressure-variable adsorption device that molecular sieve is sorbent material, finally by filtering buffering, deliver to Yong Qi workshop section.It can promote under the prerequisite of recover hydrogen quality, reduces cost of investment, reduces running cost.

The object of the invention is to complete like this: it is by polysilicon production process, reduction transforms tail gas recycle products obtained therefrom recover hydrogen, after original adsorption tower is handled, process recover hydrogen purifying is at 15bar, in the time of temperature 25-35 ℃, the Temp .-changing adsorption device that process silica gel and gac are sorbent material, remove the HCL of trace in recover hydrogen, chlorosilane, through take the pressure-variable adsorption device that molecular sieve is sorbent material, adopt pressure swing adsorption technique to reduce the methane in recover hydrogen again, a nitrogen content, a nitrogen content is down to below 100ppmv, methane content is down to below 50ppmv, buffering is delivered to Yong Qi workshop section after filtration,

Reduction transforms the Temp .-changing adsorption device that tail gas recycle products obtained therefrom recover hydrogen is sorbent material through silica gel and gac in the time of pressure 15bar, temperature 25-35 ℃, remove HCL, the chlorosilane of trace in recover hydrogen, Temp .-changing adsorption device is the using and the reserved, and adsorption time is to switch once for 12 hours; Through take the pressure-variable adsorption device that molecular sieve is sorbent material, reduce methane, the nitrogen in recover hydrogen again, it is that many employing sequencing valves are controlled that transformation is inhaled adsorber, and adsorber automatically switches once for 130 seconds.

The feature of Recovering Hydrogen during Production of Polycrystalline Silicon purifying process of the present invention is: on the basis of original technique adsorption unit, increase gac, silica gel Temp .-changing adsorption device, molecular sieve pressure-variable adsorption device effectively reduces methane, a nitrogen content in recover hydrogen.This technique input cost is low, and working cost is relatively cheap, is applicable to large-scale industrialization and produces.

In production of polysilicon of the present invention, the purifying process ，Wo company of reduction conversion tail gas recycle gained recover hydrogen processes in polysilicon production process and has improved the quality of recover hydrogen, thereby has improved the quality of polysilicon finished product, and the economic benefit of generation is very considerable.

Four, accompanying drawing explanation

Accompanying drawing 1 Recovering Hydrogen during Production of Polycrystalline Silicon purifying process schema.

Five, embodiment

Below in conjunction with drawings and Examples, the present invention is described in further detail:

With reference to accompanying drawing, in production of polysilicon of the present invention, reduction transforms the purifying process of tail gas recycle gained recover hydrogen, the Temp .-changing adsorption device that first recover hydrogen is aborning sorbent material through silica gel and gac when 30 ℃ of 15bar, temperature, remove HCL, the chlorosilane of trace in recover hydrogen, Temp .-changing adsorption device is the using and the reserved, and adsorption time is to switch once for 12 hours; And then reduce methane, the nitrogen in recover hydrogen through take the pressure-variable adsorption device that molecular sieve is sorbent material, and this adsorber is that many employing sequencing valves are controlled, adsorber automatically switches once for 130 seconds.This whole technological process can be down to a nitrogen content below 100ppmv, and methane content is down to below 50ppmv, finally by filtering buffering, delivers to Yong Qi workshop section.

Claims

1. in a production of polysilicon, reduction transforms tail gas recycle gained hydrogen purification technique, it is characterized in that: it is by polysilicon production process, reduction transforms tail gas recycle products obtained therefrom hydrogen, after original adsorption tower is handled, process hydrogen cleaning is at 15bar, in the time of temperature 25-35 ℃, the Temp .-changing adsorption device that process silica gel and gac are sorbent material, remove the HCL of trace in hydrogen, chlorosilane, through take the pressure-variable adsorption device that molecular sieve is sorbent material, adopt pressure swing adsorption technique to reduce the methane in hydrogen again, a nitrogen content, a nitrogen content is down to below 100ppmv, methane content is down to below 50ppmv, buffering is delivered to Yong Qi workshop section after filtration.

2. in production of polysilicon as claimed in claim 1, reduction transforms tail gas recycle gained hydrogen purification technique, it is characterized in that: reduction transforms the Temp .-changing adsorption device that tail gas recycle products obtained therefrom hydrogen is sorbent material through silica gel and gac in the time of pressure 15bar, temperature 25-35 ℃, remove HCL, the chlorosilane of trace in hydrogen, Temp .-changing adsorption device is the using and the reserved, and adsorption time is to switch once for 12 hours; Through take the pressure-variable adsorption device that molecular sieve is sorbent material, reduce methane, the nitrogen in hydrogen again, it is that many employing sequencing valves are controlled that transformation is inhaled adsorber, and adsorber automatically switches once for 130 seconds.