CN103130242A

CN103130242A - Preparation method of 7N optoelectronic ultra-pure ammonia three-tower rectification

Info

Publication number: CN103130242A
Application number: CN2011103986396A
Authority: CN
Inventors: 吴纳新
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-12-05
Filing date: 2011-12-05
Publication date: 2013-06-05

Abstract

The invention provides a preparation method of 7N optoelectronic ultra-pure ammonia three-tower rectification. Industrial liquid nitrogen with purity of 99.9% is adopted to prepare optoelectronic ultra-pure ammonia with the purity of 99.99999% through a three-tower rectification method. A first-stage rectification tower can remove moisture, high-boiling-point substances and metal impurities in ammonia in a tower kettle. A second-stage rectification tower can remove light components such as hydrogen (H2), oxygen (O2), nitrogen (N2), methane (CH4), carbonic oxide (CO) and carbon dioxide (CO2) on a tower top. A third-stage rectification tower can further remove heavy components such as the moisture in the ammonia in the tower kettle and removes the light components in the ammonia on the tower top, and therefore the 7N optoelectronic ultra-pure ammonia is obtained. Novel chemical impurities and particles are likely to be brought in during the removal process of the moisture and oxygen in the ammonia through a catalyzed sorption method. The preparation method can avoid external pollution to the largest extent, and the superior ultra-pure ammonia meeting requirements of optoelectronic semiconductor epitaxy is obtained.

Description

Three-tower rectification is produced the method for 7N photoelectricity sub level ultra-pure ammonia

Technical field:

The present invention adopts three-tower rectification to be produced the method for 99.99999% photoelectricity sub level ultra-pure ammonia by 99.9% industrial liquid ammonia.The purification technique that relates to ultra-pure photoelectricity sub level special gas.

Technical background:

In recent years, along with Global Oil equal energy source resource reduces gradually, clean energy and power-saving technology are greatly developed in countries in the world, pay close attention to low-carbon economy.Under this background, the solar cell of China and LED technology and related industries have obtained fast development.In manufacturing solar cell and LED chip process, all need to use a large amount of ultra-pure ammonia as nitrogenous source, especially LED chip is when growth, and the purity of ammonia used is higher, and the LED power consumption of preparation is less, and luminous intensity is larger.

The epitaxy of LED refers to that applied metal organic chemical vapor deposition technique MOCVD grows specific monocrystal thin films on certain substrate material.Be widely used as in the preparation process of efficient blue-ray LED of back light need to be on saphire substrate material the growing GaN single crystal film.Wherein, Ga from metal organic source (MO source) as trimethyl-gallium (TMG); N is from the ultra-pure ammonia nitrogenous source.As seen ultra-pure ammonia is one of three large core materials of blue-ray LED epitaxial wafer.And the purity of photoelectricity sub level ultra-pure ammonia need to reach 6N4 or more than 7N.

Producing of ultra-pure ammonia is all generally to adopt industrial liquid ammonia to come except various light constituent (H in deammoniation by physico-chemical processes such as catalytic adsorption, rectifying, filtrations ₂, O ₂, N ₂, CH ₄, CO, CO ₂) impurity, high boiling material, water and metallic impurity etc.The technological process more complicated, especially adopt the catalytic adsorption method except anhydrate and the process such as oxygen in might bring new impurity atom into.Therefore the present invention can be that raw material is directly produced the 7N ultra-pure ammonia by industrial liquid ammonia, can avoid extraneous contamination as far as possible, reaches the required better ultra-pure ammonia of optoelectronic semiconductor extension.

Summary of the invention:

According to the purity of industrial liquid ammonia, the top grade product are 99.9%.The difference of the raw materials such as the coal that adopts along with synthesis ammonia plant, oil and natural gas, the impurity in industrial liquid ammonia form also has any different, and the general analysis result: in ammonia, water is 500-1000ppm, other H ₂, O ₂, N ₂, CH ₄, CO, CO ₂Deng all tens to hundreds of ppm, also have a small amount of oils and metallic impurity etc.

The present invention adopts three grades of rectificating methods, and first step rectifying tower can be removed moisture, high boiling material and metallic impurity in tower reactor, and second stage rectifying tower can be removed light constituent at tower top, and third stage rectifying tower can further be removed the heavy constituents such as moisture at the bottom of tower; Remove light constituent at tower top, obtain the 7N ultra-pure ammonia.Specific embodiment is seen accompanying drawing 1.

At first raw materials ammonia enters gasifier 1, then enter first step rectifying tower 3 through accurate filter 2, tower reactor reboiler 4 use hot water heating evaporation backflow liquefied ammonia, and discharge on a small quantity moisture useless ammonia, overhead condenser 5 use refrigerated water cooling liquid ammonias make liquefied ammonia be back to rectifying tower 3 tops by header tank 6.Header tank 6 top ammonias enter two-stage rectification tower 7, tower reactor reboiler 8 use hot water heating evaporation backflow liquefied ammonia are sent into three grades of rectifying tower 11 to the liquefied ammonia of preliminary purification simultaneously, overhead condenser 9 use refrigerated water cooling liquid ammonias, and making liquefied ammonia be back to rectifying tower 7 tops by header tank 10, in ammonia, light constituent impurity is discharged by header tank 10 tops.Enter the pure ammonia of three grades of rectifying tower 11, further discharge the evaporation of backflow liquefied ammonia with moisture useless ammonia by tower reactor reboiler 12.Ammonia liquefaction and by header tank 14, part liquefied ammonia is sent into rectifying tower 11 tops as phegma at overhead condenser 13.Another part liquefied ammonia is sent into products pot 15 as the ultra-pure ammonia product, can further discharge light constituent impurity in ammonia by the top of header tank 14.

Implementation example:

Produce 2000t ultra-pure ammonia device per year, enter the ammonia amount 270Kg/h of first step rectifying tower 3, wherein consist of NH ₃99.9%, H ₂100ppm, O ₂100ppm, N ₂200ppm, CH ₄50ppm, CO 20ppm, CO ₂30ppm, moisture 500ppm.Discharge moisture useless ammonia 2-3Kg/h at tower reactor reboiler 4, to enter in the ammonia of second stage rectifying tower 7 the light constituent foreign matter content substantially constant for the ammonia on header tank 6 tops below overhead condenser 5, and moisture content can be down to below 100ppb.3-5Kg/h can be discharged containing ammonia light constituent waste gas in header tank 10 tops below the overhead condenser 9 of second stage rectifying tower 7, and more than the tower reactor reboiler 8 bottom liquefied ammonia purity 6N of second stage rectifying tower 7, various impurity form all below 100ppb.After sending into third stage rectifying tower 11, can discharge 1-2Kg/h to the liquefied ammonia waste liquid that contains minor amount of water in tower reactor reboiler 12, the top of the header tank 14 below overhead condenser 13 can be discharged 2-4Kg/h to the useless ammonia that contains a small amount of light constituent impurity, send rectifying tower 11 trim the top of column at some liquefied ammonia of the bottom of header tank 14, another part liquefied ammonia has reached more than 7N purity sends into the ultra-pure liquefied ammonia output of products pot 15. 258Kg/h, and extraction yield is more than 95%.Wherein ammonia purity is 99.99999%, light constituent impurity H ₂, O ₂, N ₂, CH ₄, CO, CO ₂All be less than 10ppb, moisture is less than 50ppb.

Claims

1. the present invention adopts the three-tower rectification method to produce 99.99999% photoelectricity sub level ultra-pure ammonia by 99.9% industrial liquid ammonia.

2. first step rectifying tower of the present invention can be in tower reactor except moisture in deammoniation, high boiling material and metallic impurity etc.

3. the second stage of the present invention rectifying tower can be at tower top except light constituent H in deammoniation ₂, O ₂, N ₂, CH ₄, CO, CO ₂Deng.

Third stage rectifying tower of the present invention can be further in tower reactor except heavy constituents such as moisture in deammoniation, except light constituent in deammoniation, obtain the 7N ultra-pure ammonia at tower top.

5. Operating parameters of three grades of key equipments such as rectifying tower of the present invention etc. all belongs to this patent protection domain.