|Usage::||Heating Treatment , Industrial||High Purity::||99.999%|
|Flow Rate::||500Nm3/h||Dew Point::||-40℃|
High purity 99.999% nitrogen generator with nitrogen carobn deoxidization purification system
I.Description of Design Scheme for Nitrogen Production System
1. Compressed air system
Air compressor supply the raw material air for the nitrogen generator. The nitrogen making system need high quality,stable pressure and enough air consumption.Air compressor should use the reliable, maintenance easily,low noise,screw air compressor.
2.Compressed air purification system
Compressed air pass through 9 levels filters,then pass through cooling type dryer, the compressed air cooling,let the vapour in the air condensation into water,along with dust,oil drain out the machine.It’s better to put the cooling dryer in the compressor room.
The technological process uses a freeze dryer to remove oil and water. There are four reasons: first, the maximum liquid load at the air inlet of the post-stage 7-stage air supply pipeline filter is 2000ppm w/w (dew point ﹤ 12℃), and the 7-stage air supply pipeline filter without a freeze dryer is liable to fail; Second, the outdoor temperature is relatively low in winter, and water is separated out after the compressed air temperature is reduced, thus blocking the pipeline system, which needs to be tilted and drained. Third, the pipeline system is easy to corrode and rust after water is separated out. Fourth, air purification is essential if nitrogen purity is to be improved in the future.
The rear stage of the cooling dryer is a precision filter set,the precision filter group consists of secondary filters.One is 7 grade main pipeline filters,another is 5 grade high quality oil removing filter.7 grade main pipeline filter precision is 1um,filter out 1um and larger solid state and liquid particle,vestigital oil content 1ppm w/w.5 grade high quality oil mist removing filter filtrate precision 0.01um,remove 0.01um and larger solid state and liquid particle, 99.9999+% oil mist,the rest oil content 0.001 ppm w/w. Compressed air quality can reach 1 class according to ISO8573.1. Such clean and dry compressed air can inlet active carbon filter,air buffer tank then inlet nitrogen generator part,after PSA device make out the nitrogen purity ≥99.5%.
Note: Tongyue emphasized that activated carbon filter and air buffer tank should be equipped in the compressed air purification system.
(1) The purpose of configuring the activated carbon filter is that when the filter element of the current air filter is not replaced in time, the activated carbon filter can adsorb impurities in compressed air to protect the carbon molecular sieve of the pressure swing adsorption nitrogen generator;
(2) The purpose of configuring the air buffer tank is that the working principle of the PSA nitrogen generator determines the periodic switching of the two towers. Due to the large pressure difference during switching, the instantaneous flow rate of air will be greater than the rated processing volume of the air filter and freeze dryer, thus the quality of compressed air cannot be guaranteed. When the air buffer tank is configured, the air buffer tank can provide instantaneous large flow of compressed air and ensure the quality of compressed air, thus ensuring the gas production effect and service life of the PSA nitrogen generator.
3.Pressure Swing Adsorption Nitrogen Generator System
Pressure Swing Adsorption(PSA)is an advanced gas separate technique,it is widely used in gas supply field in the world.
3.1 PSA technology has the following advantages
* The purity of the product can be adjusted with the change of flow rate;
* work under low pressure and normal pressure, safe and energy saving;
* simple equipment, easy maintenance;
* microcomputer control, fully automatic unmanned operation;
3.2 Adsorbing material
Adsorbing material is the center part of PSA nitrogen generator,Normally use the the Carbon Molecular Sieve,it can adsorb the O2,CO2,water in the air,but can’t adsorb the nitrogen.
3.3 PSA principal
Because O2 and N2 these two gas molecule have diffusion rate ,difference on the molecule sieve surface,O2 smaller diameter can diffuse faster,most of them inlet micropore of CMS,the large diameter N2 diffuse slowly,less of them can inlet .This difference in selective adsorption of oxygen and nitrogen by carbon molecular sieves leads to the enrichment of oxygen in the adsorption phase and nitrogen in the gas phase in a short period of time. Thus, oxygen and nitrogen are separated and the gas phase enriched nitrogen is obtained under PSA conditions.
II. Brief Introduction of Type TYD99.999-500 Carbon and Nitrogen Purification Equipment
1 Process flow
The characteristic of combustion catalyst reacting with oxygen at high temperature is mainly used to remove impurity oxygen in nitrogen. The chemical equation is as follows:
C + O2 → CO2↑+ Q
Since the oxygen content in low purity nitrogen is very low, and the oxygen content in 99.9% nitrogen is 1000ppm, to reduce the oxygen content to 10ppm(99.999% purity nitrogen), the design must ensure the complete reaction of oxygen and carbon (oxygen content ≤1.5ppm)! However, it is very unstable to use a single carbon-added deoxidation tower, because small leakage or other faults in the single tower will directly affect the oxygen content. In addition, when the combustion temperature is not enough, the oxygen reaction will also be incomplete, which will also lead to the oxygen content falling below the acceptable value.
To sum up, there are two conditions that must be met by the carbon addition deoxidation and purification equipment:
First, the deoxidation tower adopts two towers or more processes;
Second, a reasonable combustion temperature in the deoxidation tower is required, and heating pipes with sufficient power are used for heating.
In order to ensure that the oxygen scavenger is replaced without shutdown, the scheme adopts double sets of deoxidizing towers.
Deoxidization tower: it is a tower-type pressure vessel filled with deoxidization catalyst (main component: c), heater, airflow distribution device, etc. According to the relationship between the chemical reaction principles of oxygen and carbon, ordinary nitrogen enters the heated combustion tower, and the oxygen in ordinary nitrogen reacts with the carbon catalyst in the catalyst to remove the oxygen in low-purity nitrogen and generate carbon dioxide, dust and heat at the same time. These impurities need to be removed through the following process to obtain high purity nitrogen.
Heat exchanger: a large amount of heat is generated in the combustion process of oxygen and carbon, and the finished gas needs nitrogen at about 40℃ and needs to be cooled down. however, the higher the temperature of nitrogen entering the deoxygenation, the better, and the higher the temperature, the faster the reaction can be accelerated. therefore, high-efficiency heat exchange between nitrogen after reaction and nitrogen before reaction can kill two birds with one stone, reducing the heating power of the deoxygenation tower and the cooling load of nitrogen at the rear.
Preheating system: also called external heating system, is a heating method with relatively high heating efficiency. The nitrogen from the nitrogen heat exchanger is heated to 280℃ and enters the deoxygenation tower to further ensure the reaction temperature and ensure the stable operation of the purification device.
High-efficiency water cooler: the temperature of nitrogen from the "hot outlet" of the heat exchanger is about 150℃, and enters the high-efficiency water cooler for cooling treatment, reaching about 40℃ after cooling.
Micro-thermal regeneration dryer: Micro-thermal adsorption type compressed air dryer is a device that uses pressure swing adsorption principle and micro-thermal regeneration method to dry compressed air. Advanced technologies such as a novel plunger-type cut-off valve and a digital display electronic program intelligent controller are adopted, and the device has the characteristics of automatic timing, automatic switching and regeneration conversion, analog display of working state, less regeneration gas consumption and the like. 13X adsorbent is installed inside, which has very strong water absorption and can selectively adsorb CO2.
All internal pipe fittings and components in the system shall be provided by the seller:
(3) Complete instrument and control system (including PLC, on-line continuous nitrogen and oxygen analyzer, orifice meter, etc. for each set of pressure swing adsorption nitrogen making device).
(4) The carbon molecular sieve attached to the nitrogen generator in the plant system and the adsorbent attached to the purification equipment, etc.
(5) The supplier shall provide matching flanges, gaskets and fasteners, pressurization equipment, spare parts and special tools for site start-up and one-year use and internal support of equipment at the joint with the buyer.
(6) Painting, including primer and topcoat.