阅读说明：本技术 一种放空尾气中三氟化氮气体的回收设备和回收方法 (Recovery device and recovery method for nitrogen trifluoride gas in vented tail gas ) 是由 马朝选 纪振红 王振宇 林坤 张明杰 王军岭 宋忠华 赵志刚 于 2021-09-24 设计创作，主要内容包括：本发明提供了一种放空尾气中三氟化氮气体回收设备,包括一级回收塔和二级回收塔,所述一级回收塔的上端连接有第一连接管,所述二级回收塔的上端连接有第二连接管,所述一级回收塔的一端连接有第一模压机,所述二级回收塔的一端连接有第二模压机,所述第二模压机的一端连接有纯化输送管线；本发明还公开了一种放空尾气中三氟化氮气体回收方法,包括以下步骤。本发明利用模压机将放空尾气进行加压至回收塔,利用液氮控制回收塔温度,进而实现尾气中三氟化氮回收,实现排放尾气中三氟化氮达标排放,本发明的回收工艺中,既保证尾气达标排放,符合环保要求,又提高了生产中三氟化氮收集率,提高经济效益。(The invention provides equipment for recovering nitrogen trifluoride gas from vented tail gas, which comprises a primary recovery tower and a secondary recovery tower, wherein the upper end of the primary recovery tower is connected with a first connecting pipe, the upper end of the secondary recovery tower is connected with a second connecting pipe, one end of the primary recovery tower is connected with a first mould press, one end of the secondary recovery tower is connected with a second mould press, and one end of the second mould press is connected with a purification conveying pipeline; the invention also discloses a method for recovering nitrogen trifluoride gas from the vented tail gas, which comprises the following steps. According to the invention, the vented tail gas is pressurized to the recovery tower by using the mould press, the temperature of the recovery tower is controlled by using liquid nitrogen, so that the recovery of nitrogen trifluoride in the tail gas is realized, and the standard emission of nitrogen trifluoride in the emitted tail gas is realized.)

1. The utility model provides a nitrogen trifluoride gas recovery plant in unloading tail gas which characterized in that: the device comprises a primary recovery tower (5) and a secondary recovery tower (12), wherein one end of the secondary recovery tower (12) is connected with a second mould pressing machine (9), one end of the second mould pressing machine (9) is connected with a purification conveying pipeline (2), the upper end of the primary recovery tower (5) is connected with a first connecting pipe (14), one end of the first connecting pipe (14) is connected to one side of the purification conveying pipeline (2), the upper end of the secondary recovery tower (12) is connected with a second connecting pipe (10), one end of the purification conveying pipeline (2) is connected to the upper end of the second connecting pipe (10), one end of the second connecting pipe (10) is connected with a fixed pipe (11), and the purification conveying pipeline (2) is connected with a guide pipe (1);

the other side end of the primary recovery tower (5) is also connected with a first mould press (6).

2. The equipment for recovering nitrogen trifluoride gas from vented tail gas according to claim 1, wherein the primary recovery tower (5) and the secondary recovery tower (12) are connected at their upper ends with a cold nitrogen discharge pipe (4) respectively, and the primary recovery tower (5) and the secondary recovery tower (12) are connected at their lower ends with a liquid nitrogen delivery pipe (13) respectively.

3. The apparatus for recovering nitrogen trifluoride gas from vented tail gas as claimed in claim 1, wherein mounting brackets (8) are fixed to the lower ends of said first molding press (6) and said second molding press (9), respectively.

4. A plant for the recovery of nitrogen trifluoride gas from vented offgas according to claim 1, characterized in that the lower end of the first molding press (6) is connected to an offgas vent pipe (7).

5. The apparatus for recovering nitrogen trifluoride gas from vented tail gas according to claim 1, wherein the first connecting pipe (14) and the second connecting pipe (10) are each provided with a pressure reducing valve (3).

6. A method for recovering nitrogen trifluoride gas from vented tail gas is characterized by comprising the following steps:

s1, pressurizing the vented tail gas in the pretreatment stage by a first mould pressing machine (6) to enable the vented tail gas to enter a primary recovery tower (5);

s2, controlling recovery by using liquid nitrogen in a primary recovery tower (5), and liquefying most of nitrogen trifluoride in the vented tail gas;

s3, re-pressurizing the residual tail gas treated by the primary recovery tower (5) through a second mould pressing machine (9) to enable the residual tail gas to enter a secondary recovery tower (12), wherein the pressure and the temperature are the same as the parameters of the primary recovery tower (5), and further recovering the residual nitrogen trifluoride;

s4, performing secondary recovery by a secondary recovery tower (12), wherein the content of nitrogen trifluoride in tail gas discharged from a fixed pipe (11) is less than 3 ppm; when the liquid level of the first-stage recovery tower (5) reaches 1/2 or the liquid level of the second-stage recovery tower (12) reaches 1/3, the first-stage recovery tower (5) and the second-stage recovery tower (12) are heated by standby recovery equipment for recovery, and gasified nitrogen trifluoride is sent to a subsequent purification section through a discharge pipe (1): the high-purity nitrogen trifluoride gas with the purity of more than 99.995 percent is obtained through the working procedures of cracking, washing, reduction, alkali washing, continuous rectification and the like.

7. A process for recovering nitrogen trifluoride gas from vented offgas according to claim 6, wherein in S1, the pressure of the first molding press (6) is 5 to 7 MPa.

8. The method for recovering nitrogen trifluoride gas from vent tail gas according to claim 6, wherein in S1, the vent tail gas is vent tail gas from pretreatment stage in production, and its composition includes the following gases by volume percent: 98-98.5% of nitrogen, 1-1.5% of nitrogen trifluoride and the balance of carbon dioxide, hydrogen and impurities thereof.

9. The method for recovering nitrogen trifluoride gas from vented tail gas according to claim 6, wherein the temperature of the liquid nitrogen controlled recovery at S2 is controlled to be from-45 ℃ to-95 ℃.

Technical Field

The invention belongs to the technical field of nitrogen trifluoride recovery, and particularly relates to a recovery device and a recovery method for nitrogen trifluoride gas in exhausted tail gas.

Background

Nitrogen trifluoride is a colorless, odorless and stable gas at normal temperature, is a strong oxidant, is used as an excellent plasma etching gas in the microelectronic industry, is cracked into active fluorine ions during ion etching, has excellent etching rate and selectivity (for silicon oxide and silicon) for silicon and tungsten compounds, is a very good cleaning agent for high-purity nitrogen trifluoride, does not leave any residue on the surface of an etching object during etching, and is widely applied to chip manufacturing and high-energy lasers.

Nitrogen trifluoride has excellent etching rate and selectivity, no residue is left on the surface of an etched object, and the nitrogen trifluoride is also a very good cleaning agent. With the development of nanotechnology and the large-scale development of technology in the electronics industry, the demand for it will increase.

However, the collection rate is low in the existing preparation process of nitrogen trifluoride, the emission of the content of nitrogen trifluoride in the emptying tail gas is not up to the standard, and the air is polluted; therefore, an apparatus and a method for recovering nitrogen trifluoride gas from vented tail gas are provided to solve the above problems.

Disclosure of Invention

The technical problem to be solved by the present invention is to provide a device for recovering nitrogen trifluoride gas from vented tail gas, aiming at overcoming the defects of the prior art, and solving the problems proposed in the background art.

In order to solve the technical problems, the invention adopts the technical scheme that:

in a first aspect, the equipment for recovering nitrogen trifluoride gas from the exhausted tail gas comprises a primary recovery tower and a secondary recovery tower, wherein one end of the secondary recovery tower is connected with a second mould press, one end of the second mould press is connected with a purification conveying pipeline, the upper end of the primary recovery tower is connected with a first connecting pipe, one end of the first connecting pipe is connected to one side of the purification conveying pipeline, the upper end of the secondary recovery tower is connected with a second connecting pipe, one end of the purification conveying pipeline is connected to the upper end of the second connecting pipe, one end of the second connecting pipe is connected with a fixed pipe, and a delivery pipe is connected to the purification conveying pipeline;

the other side end of the primary recovery tower is also connected with a first molding press.

Furthermore, one side of the upper end of the first-stage recovery tower and one side of the upper end of the second-stage recovery tower are respectively connected with a cold nitrogen discharge pipe, and one side of the lower end of the first-stage recovery tower and one side of the lower end of the second-stage recovery tower are respectively connected with a liquid nitrogen conveying pipe.

Furthermore, the lower ends of the first molding press and the second molding press are respectively fixed with a mounting bracket.

Further, the lower end of the first molding press is connected with a tail gas emptying pipe.

Furthermore, the upper ends of the first connecting pipe and the second connecting pipe are respectively provided with a pressure reducing valve.

In a second aspect, the method for recovering nitrogen trifluoride gas from the vented tail gas comprises the following steps:

s1, pressurizing the vented tail gas in the pretreatment stage by a first mould pressing machine, and enabling the vented tail gas to enter a primary recovery tower;

s2, controlling recovery by using liquid nitrogen in a primary recovery tower, and liquefying most of nitrogen trifluoride in the vented tail gas;

s3, re-pressurizing the residual tail gas treated by the primary recovery tower through a second mould press, and enabling the residual tail gas to enter a secondary recovery tower, wherein the pressure and the temperature are the same as the parameters of the primary recovery tower, so that the further recovery of the residual nitrogen trifluoride is realized;

and S4, performing secondary recovery by a secondary recovery tower, wherein the content of nitrogen trifluoride in tail gas reaches below 3ppm, heating the secondary recovery tower when the liquid level of the recovery tower reaches 1/3, and further purifying the gasified nitrogen trifluoride in a purification section through a discharge pipe.

Further, in S1, the pressure of the first molding press is 5 to 7 MPa.

Further, in S1, the vent tail gas is the vent tail gas of the pretreatment stage in the production, and the vent tail gas mainly comprises 98-98.5% of nitrogen, 1% of nitrogen trifluoride and the balance of carbon dioxide.

Further, in S2, the liquid nitrogen is controlled to recover at a temperature of-45 ℃ to-95 ℃.

Compared with the prior art, the invention has the following advantages:

according to the recovery process, the vented tail gas is pressurized to the recovery tower through the mould press, the temperature of the recovery tower is controlled by using liquid nitrogen, so that the recovery of nitrogen trifluoride in the vented tail gas is realized, and the emission requirement of the content of nitrogen trifluoride in the exhausted tail gas is met.

Drawings

FIG. 1 is a flow chart of the apparatus of the present invention.

The system comprises a guide pipe 1, a purification conveying pipeline 2, a pressure reducing valve 3, a cold nitrogen gas discharge pipe 4, a primary recovery tower 5, a first mould press 6, a tail gas vent pipe 7, an installation support 8, a second mould press 9, a second connecting pipe 10, a fixed pipe 11, a secondary recovery tower 12, a liquid nitrogen conveying pipe 13 and a first connecting pipe 14.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Embodiment 1, as shown in fig. 1, the present invention provides a technical solution: the utility model provides a nitrogen trifluoride gas recovery equipment in unloading tail gas, including one-level recovery tower 5 and second grade recovery tower 12, the upper end of one-level recovery tower 5 is connected with first connecting pipe 14, the upper end of second grade recovery tower 12 is connected with second connecting pipe 10, the one end of one-level recovery tower 5 is connected with first moulding press 6, the one end of second grade recovery tower 12 is connected with second moulding press 9, the one end of second moulding press 9 is connected with purification conveying pipeline 2, the one side at purification conveying pipeline 2 is connected to the one end of first connecting pipe 14, the upper end at second connecting pipe 10 is connected to the one end of purification conveying pipeline 2, the one end of second connecting pipe 10 is connected with fixed pipe 11, the unloading tower is connected to the one end of fixed pipe 11, be connected with contact tube 1 on the purification conveying pipeline 2, nitrogen trifluoride after the gasification advances to purify the purification workshop section through contact tube 1 and further purifies.

In this embodiment, the upper end side of the first-stage recovery tower 5 and the upper end side of the second-stage recovery tower 12 are both connected with a cold nitrogen gas discharge pipe 4, and the lower end side of the first-stage recovery tower 5 and the lower end side of the second-stage recovery tower 12 are both connected with a liquid nitrogen delivery pipe 13.

In this embodiment, the lower ends of the first molding press 6 and the second molding press 9 are both fixed with a mounting bracket 8, the lower end of the first molding press 6 is connected with a tail gas vent pipe 7, and the upper ends of the first connecting pipe 14 and the second connecting pipe 10 are both provided with a pressure reducing valve 3, which facilitates internal pressure adjustment.

Embodiment 2, a process for recovering nitrogen trifluoride gas from vented tail gas, comprising the steps of:

s1, pressurizing the vent tail gas in the pretreatment stage by a first mould press 6, wherein the vent tail gas is the vent tail gas in the pretreatment stage in the production process and mainly comprises 98-98.5% of nitrogen, 1% of nitrogen trifluoride and the balance of carbon dioxide, and the pressure of the first mould press 6 is 5-7MPa, so that the vent tail gas enters a primary recovery tower 5;

s2, controlling recovery by using liquid nitrogen in a primary recovery tower 5, and liquefying most of nitrogen trifluoride in the vented tail gas;

s3, re-pressurizing the residual tail gas treated by the primary recovery tower 5 by a second mould press 9, enabling the residual tail gas to enter a secondary recovery tower 12, wherein the pressure and the temperature are the same as the parameters of the primary recovery tower 5, further recovering the residual nitrogen trifluoride, and controlling the recovery temperature to be-45 ℃ to-95 ℃ by liquid nitrogen;

s4, performing secondary recovery by the secondary recovery tower 12, wherein the content of nitrogen trifluoride in tail gas reaches below 3ppm, when the liquid level of the recovery tower reaches 1/3, heating the secondary recovery tower 12, and further purifying the gasified nitrogen trifluoride by a purification section through a discharge pipe 1.

The method has the main advantages that the low-concentration nitrogen trifluoride gas is pressurized by the mould press, the boiling point of the nitrogen trifluoride gas at high pressure is reduced, the nitrogen trifluoride gas is easy to liquefy and recycle, and the low-concentration nitrogen trifluoride gas is fully recycled by the secondary recycling device.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.