WO2022055442A1

WO2022055442A1 - Nitrogen gas dryer system after purifier for obtaining high purity nitrogen in nitrogen purification applications

Info

Publication number: WO2022055442A1
Application number: PCT/TR2020/050952
Authority: WO
Inventors: Ibrahim Kemal YAZICI
Original assignee: Mikropor Makina Sanayi Ve Ticaret Anonim Sirketi
Priority date: 2020-09-10
Filing date: 2020-10-16
Publication date: 2022-03-17
Also published as: TR202014370A2

Abstract

The invention relates to producing nitrogen gas with critical dew point, which is needed in the industry for high purity nitrogen use, without any loss of nitrogen. The system of the invention comprises a nitrogen generator supplying nitrogen required to the system; nitrogen enriching catalyst unit called "Deoxo" for introducing low purity (99.5% and 99.9%) nitrogen gas from the nitrogen generator and purifying it; two PSA type dryers (6,7) working with the principle of pressure swing adsorption (PSA); a plurality of normally open and normally closed solenoid valves (8,9); a plurality of three-way valves (4,5,10) located in following parts of the system, for determining the direction of gas going to the dryers working with the adsorption principle; a plurality of solenoid valves (2,3) for utilizing the compressed air line in the regeneration steps of the adsorption dryers in order to avoid any loss of pure nitrogen gas.

Description

NITROGEN GAS DRYER SYSTEM AFTER PURIFIER FOR OBTAINING HIGH

PURITY NITROGEN IN NITROGEN PURIFICATION APPLICATIONS

Field of the Invention

The invention relates to a system comprising an adsorption type dryer unit that will allow the dew point value of the water formed after the reaction to be <-40 ° C after the puri fier unit , which contains special catalysts containing palladium and allows nitrogen gas with 99 . 5% or 99 . 9% purity to reach 99 . 999% purity in applications requiring nitrogen gas puri fication .

Known State of the Art

High purity nitrogen gas is needed in many areas in the industry . For obtaining nitrogen gas with high purity, liquid ( cryogenic tanks ) and pure nitrogen tanks are generally used, and recently it is provided by means of pressure swing adsorption ( PSA) and subsequently catalyst units called "Deoxo" .

In order to meet the needs of industrial branches that require high purity nitrogen ( steel manufacturing, glass industry, petroleum and food sector, etc . ) and other industrial areas , it is used as a solution in a way that provides savings in all aspects together with the PSA unit and nitrogen puri fier units . However, some needs have emerged where it is not suf ficient for dew point value of high purity nitrogen gas to be <3 ° C .

On palladium catalysts with large surface area in the nitrogen puri fier unit , hydrogen molecules and oxygen molecules are reacted to release water and the oxygen content is reduced below 10 ppm . With this working principle of the nitrogen purifier unit, it can be seen that it is possible to obtain high purity nitrogen.

In the state of art, while increasing 99.9% and 99.95% purity of nitrogen gas to high purities by means of nitrogen purification units, the temperature in the purifier unit rises to 80 °C due to the exothermic (releasing heat) processes performed, the dew point of nitrogen gas rises to 25 °C due to temperature increase. Dryer units must be used to separate the water and moisture resulting from the exothermic reaction occurred in the nitrogen purifier unit from high purity nitrogen. This dryer unit, which is essential to use in available systems, can reduce the dew point value that is observed after the catalyst to a maximum of 3 °C. It is not efficient and convenient to use high purity nitrogen gas directly through the line due to exposure to a temperature of 80°C in the tank as a result of exothermic reactions and the effects of other exothermic reactions. With the widespread use of nitrogen gas in the industrial field and the specialization of needs, there is a need for a critical dew point of -40 °C in areas where 3°C is not sufficient for the critical dew point value. In the known state of the art, a system developed for fulfilling this need is not available.

An example of the known state of the art is the patent document KR100877511B1 . The document relates to a system that produces high purity nitrogen gas to supply high purity nitrogen gas required in an operation, and freely control the supply amount and supply pressure of nitrogen gas as per working conditions. It is stated that this system comprises an air compressor, an air purification unit, a nitrogen generator, a nitrogen purification unit, a pressure booster unit, a pressure tank and a pressure regulator. It is stated that the air purification unit removes impurities and water in compressed air supplied by the air compressor to puri fy the compressed air ; the nitrogen generator separates and discharges nitrogen gas only from the puri fied compressed air ; the nitrogen puri fication unit reacts nitrogen gas containing oxygen with hydrogen under a platinum catalyst to increase the purity of the nitrogen gas by removing oxygen contained in the nitrogen gas .

Another example of the known state of the art is the utility model no . CN2526312Y . The document relates to a puri fying device for removing oxygen and water from nitrogen . It is stated that the device of the utility model comprises a hydrogen oxygen retort containing a palladium catalyst , a cooler, a filter , and a retort , which are arranged in order and used for removing oxygen and also a controller which trans fers the absorption .

As can be seen, the documents in the known state of art do not aim to decrease the dew point suf ficiently and do not comprise a dryer system therefor .

As mentioned above , taking the industrial needs into account , it is understood that nitrogen gas should be used with high purity and very low dew point . Due to the drawbacks of present systems , there is still a need for obtaining high purity nitrogen gas with dew points at much lower values ( at -40 ° C ) compared to 3 ° C in available systems by using chemical dryers after the deoxo unit . The invention of the application is developed for ful filling this need .

Detailed Description of the Invention

The invention relates to a system comprising chemical dryer units allowing decreasing of the dew point level of high purity nitrogen gas to a maximum o f -40 ° C after high purity (minimum 99.999%) nitrogen production from low purity (99.5% and 99.9% purity level) nitrogen gas by using nitrogen purifier deoxo unit.

The object of the invention is to decrease the dew point of high purity nitrogen gas obtained after purification process to a maximum -40 °C and a minimum of -80°C. For this purpose, the system of invention uses two PSA type (Working with the Principle of Pressure Swing Adsorption) dryers.

By means of the invention, by increasing the purity value of nitrogen gas obtained from the nitrogen generator with 99.5% purity to the level of 99.999%, both a significant cost saving is achieved and minimum dew point level in state of art of high purity nitrogen gas is decreased from 3 °C to -40 °C by two chemical dryers placed after the compact deoxo unit.

The system of the invention comprises, in general;

- a nitrogen generator supplying nitrogen required to the system,

- a compact deoxo unit that allows reacting of nitrogen from the nitrogen generator with hydrogen and increasing its purity to higher levels,

- more than one solenoid valve (8,9) which are normally open and normally closed,

- two PSA type (chemical) dryers (6,7) working with the principle of pressure swing adsorption,

- more than one three-way valve (4,5,10) located in following parts of the system, for determining the direction of gas going to the dryers working with the adsorption principle,

- more than one solenoid valve (2,3) for utilizing the compressed air line in the regeneration steps of the adsorption dryers in order to avoid any loss of pure nitrogen gas. In an embodiment of the invention, atmospheric air is used in the regeneration processes. In this way, any loss of nitrogen gas does not occur while carrying out this processes.

In an embodiment of the invention, there is a hydrogen flow meter that allows controlling of hydrogen passage by PID.

In the invention, PSA type dryers should be used to decrease dew point to a maximum of -40 °C and a minimum of -80°C Two PSA type dryers should also be used. The purpose of using two dryers working with the principle of pressure swing adsorption is to carry out regeneration processes with compressed air in order to saturate the chemical granules in a dryer while another dryer is used in the nitrogen drying process. The dew point value dried by structural features of chemical granules present in two PSA type dryer tanks used in the system can decrease to a maximum of -40°C and a minimum of -80°C.

In an embodiment of the invention, there is a first PSA type dryer (6) and a second PSA type dryer (7) placed to retain and absorb the moisture in the nitrogen gas.

In an embodiment of the invention, there are dew point meters and analyzers placed to measure quality of nitrogen gas at inlet and outlet of the system.

In an embodiment of the invention, there are piston valves at the dryer exhaust, for discharging the pressure in the tank to the atmosphere by using them in the depressurization step of the regenerated dryer tank.

In an embodiment of the invention, there is a software that controls solenoid valves (2, 3, 8, 9) , three-way valves (4,5,10) and dryer exhaust piston valves sequentially and according to a specific algorithm.

In an embodiment of the invention, there are temperature sensors placed in predetermined zones to measure temperatures of the system.

In an embodiment of the invention, there are two valves allowing the passage of hydrogen, one of which is normally closed and the other is a proportional valve that regulates the hydrogen passage.

If it is detected from the data obtained from the temperature sensors that the system has exceeded a certain level of temperature, two valves that allow hydrogen passage (the first one is normally closed valve placed for safety and the second one is the proportional valve that regulates the hydrogen passage) are completely closed and hydrogen inlet to the system is blocked.

In an embodiment of the invention, there is a three-way valve that allows the nitrogen gas obtained with high purity (minimum 99.999%) by passing through a purification unit to pass through two PSA type dryers (6,7) sequentially after entering the system. In other words, while nitrogen gas is dried by two PSA type dryers (6,7) as a result of sequential processes, said three-way valve allows nitrogen gas to enter one of PSA type dryers (6,7) .

In an embodiment of the invention, there is a first solenoid valve (2) and a second solenoid valve (3) that allow compressed air inlet (12) in order to prevent nitrogen loss in the regeneration line that PSA type dryer units (6,7) need while bringing nitrogen gas to critical dew points. In an embodiment of the invention, there is a first three-way valve (4) and a second three-way valve (5) controlling the passage of nitrogen-air according to order of drying and regeneration steps in nitrogen drying process of the PSA type dryer (6,7) .

Said first solenoid valve (2) , second solenoid valve (3) , first three-way valve (4) and second three-way valve (5) cut off nitrogen gas entering PSA type dryer (6,7) and allow compressed air to enter in said steps in order to avoid any loss of nitrogen during regeneration process required by the dryers while drying nitrogen gas.

In an embodiment of the invention, there is a third solenoid valve (8) and fourth solenoid valve (9) placed for allowing the passage of nitrogen gas with high purity and critical dew point after the PSA type dryer (6,7) .

In an embodiment of the invention, there is a third three-way valve (10) between two PSA type dryers (6,7) , which allows the system for nitrogen outlet according to order of nitrogen drying process.

Said third solenoid valve (8) , fourth solenoid valve (9) and third three-way valve (10) allow the passage of nitrogen gas with high purity and critical level of -40 °C formed during drying step by PSA type dryers (6,7) to the system, do not allow the passage of compressed air from PSA type dryer that regenerates, to the system, and operate sequentially.

In an embodiment of the invention, there is a storage tank (11) for storing nitrogen gas with high purity (99.999%) and low dew point (minimum -40 °C) sequentially exiting from the dryer units at the system outlet. The storage tank (11) is found in Figure-1 and Figure-6.

In figure-1 from an embodiment of the invention, there is a nitrogen inlet (1) for introducing high purity nitrogen gas to the system. Here, nitrogen enters the system and is transferred to PSA type dryers (6, 7) .

In figure-1 from an embodiment of the invention, compressed air inlets (12) are also seen. It is seen that one compressed air inlet (12) is connected to the first solenoid valve (2) and another compressed air inlet (12) to the second solenoid valve (3) .

Figures 2 to 7 are figures relating to details of the system shown in figure-1.

The invention relates to producing nitrogen gas with critical dew point, which is needed in the industry for high purity nitrogen use, without any loss of nitrogen. By using the system of the invention, nitrogen gas with high purity and low dew point (<-40°C) is produced without any loss.

The system is based on the principle of mixing 1% Hydrogen gas with nitrogen gas which is produced with 99.5% purity and contains 0.5% oxygen, in the Deoxo unit, which is the first part in the system after the nitrogen generator, releasing water with the effect of catalyst, separating the water in the system by means of the dryers located in the following parts and thus producing nitrogen with a high purity of 99.999%, and additionally producing dry nitrogen gas with a dew point of -40 °C by separating the water in the dryers. More specifically, as a result of sending nitrogen gas from the nitrogen generator to the purifier unit (deoxo unit) , introducing the nitrogen gas to the tank containing special catalyst present in the nitrogen puri fier unit , allowing the passage of hydrogen gas into the same tank by PID controls performed by taking values read by the hydrogen flow meter as a reference , and reacting oxygen and hydrogen, an exothermic reaction occurs , releasing heat and forming water . At the end of this reaction, the nitrogen gas reaches to minimum 99 . 999% purity from 99 . 5% and 99 . 9% purity and leaves the catalyst tank with water .

To remove water molecules formed at the outlet of catalyst tank of the nitrogen puri fier unit and prevent them to reach the line outlet, nitrogen gas i s first sent to the dryer system speci fically designed for high temperature for drying, and reaches to an average dew point of 3 ° C . Then it is passed through the adsorption dryers of the invention, and there is no loss of compressed nitrogen gas . Compressed air is used to regenerate the PSA type dryers . While nitrogen gas is passed through one of two PSA type adsorption type dryers located within the system, compressed air is passed through the other dryer, and thus these dryer tanks are expected to regenerate . Then the sequential steps are applied for the other dryer . The purpose of performing regeneration processes with compressed air rather than nitrogen gas is to avoid loss of high purity ( 99 . 999% ) nitrogen gas and thus to save some cost .

In summary, the invention comprises a system comprising a dryer unit used after nitrogen gas puri fication

- a nitrogen generator supplying nitrogen required to the system,

- nitrogen enriching catalyst unit called "Deoxo" for introducing low purity ( 99 . 5% and 99 . 9% ) nitrogen gas from the nitrogen generator and puri fiying it , - two PSA type dryers (6,7) working with the principle of pressure swing adsorption (PSA) ,

- a hydrogen flow meter for controlling hydrogen passage by PID,

- a plurality of normally open and normally closed solenoid valves (8,9) ,

- a plurality of three-way valves (4,5,10) located in following parts of the system, for determining the direction of gas going to the dryers working with the adsorption principle,

- a plurality of solenoid valves (2,3) for utilizing the compressed air line in the regeneration steps of the adsorption dryers in order to avoid any loss of pure nitrogen gas.

The working method of the system of the invention is as follow with the following main steps.

- providing the passage of high purity nitrogen gas from the deoxo units to a first tower of a first dryer unit, then depressurizing the tower for a certain time,

- providing the passage of compressed air to a second dryer unit at the same time and regenerating as in PSA type dryers (6,7) for a certain time,

- then depressurizing the tank for a certain time with nitrogen gas passing to a first tank of a first dryer,

- then opening a closed valve located downstream of a first dryer to which nitrogen gas passes, allowing the passage of nitrogen gas to the storage tank (11) for a certain time,

- depressurizing the tanks by opening exhaust piston valves of a second dryer for a certain time while a first tower of a first dryer is still sending dried nitrogen gas to the storage tank (11) , - then providing the passage of high purity nitrogen gas from the deoxo units to a first tower of a second dryer unit , then depressuri zing the tower for a certain time ,

- providing the passage of compres sed air to a first dryer unit at the same time and regenerating as in PSA type dryers ( 6 , 7 ) for a certain time ,

- then depressurizing the tank for a certain time with nitrogen gas passing to a second tank of a first dryer,

- then opening a closed valve located downstream of a second dryer to which nitrogen gas passes , allowing the passage of nitrogen gas to the storage tank ( 11 ) for a certain time ,

- depressuri zing the tanks by opening exhaust piston valves of a second dryer for a certain time while a first tower of a second dryer is still sending dried nitrogen gas to the storage tank ( 11 ) ,

- wherein the processes listed above is carried out sequentially for both tanks of both dryers .

The method is also under the scope of the invention .

Thanks to the invention, a system and method for producing nitrogen gas with high purity and low dew point without any loss of gas .

Explanation of the Figures

Figure-1 Overall View of the System of the Invention

Figure-2 Detailed View of the First PSA Type Dryer (Working with the Principle of Pressure Swing Adsorption) and Inlet Thereof in the System.

Figure-3 Detailed View of the First PSA Type Dryer (Working with the Principle of Pressure Swing Adsorption) and Outlet Thereof in the System.

Figure-4 Detailed View of the Second PSA Type Dryer (Working with the Principle of Pressure Swing Adsorption) and Inlet Thereof in the System.

Figure-5 Detailed View of the Second PSA Type Dryer (Working with the Principle of Pressure Swing Adsorption) and Outlet Thereof in the System.

Figure-6 Detailed View of the Inlet of Nitrogen Gas with High Purity (Min . 99 . 999% ) and Dew Point of -40 ° C Produced in the System

Figure-7 Detailed View of the Inlet of High Purity Nitrogen Gas to the System of the Invention after Deoxo Unit

Descriptions of Reference Numbers in Figures

1 . Nitrogen inlet

2 . First solenoid valve

3. Second solenoid valve

4 . First three-way valve

5 . Second three-way valve

6. First PSA type dryer 7. Second PSA type dryer

8. Third solenoid valve

9. Fourth solenoid valve

10. Third three-way valve

11. Storage tank

12. Compressed air inlet

Claims

1. A system comprising a dryer unit used after nitrogen gas purification, characterized by comprising;

- a nitrogen generator supplying nitrogen required to the system,

- nitrogen enriching catalyst unit called "Deoxo" for introducing low purity (99.5% and 99.9%) nitrogen gas from the nitrogen generator to the system and purifiying it,

- two PSA type dryers (6,7) working with the principle of pressure swing adsorption (PSA) ,

- more than one solenoid valve (2,3) for utilizing the compressed air line in the regeneration steps of the adsorption dryers in order to avoid any loss of nitrogen gas .

2. The system according to claim 1, wherein it comprises a first PSA type dryer (6) and a second PSA type dryer (7) to retain and absorb the moisture in the nitrogen gas.

3. The system according to claim 2, wherein it comprises

- a three-way valve that allows the nitrogen gas obtained with high purity (minimum 99.999%) by passing through a purification unit to pass through two PSA type dryers (6,7) sequentially after entering the system,

- a first solenoid valve (2) and a second solenoid valve (3) that allow compressed air inlet (12) in order to prevent nitrogen loss in the regeneration line that PSA type dryer (6.7) needs while bringing nitrogen gas to critical dew points ,

- a first three-way valve (4) and a second three-way valve (5) controlling the passage of nitrogen-air according to order of drying and regeneration steps in nitrogen drying process of the PSA type dryer (6,7) .

- a third solenoid valve (8) and a fourth solenoid valve (9) for allowing the passage of nitrogen gas obtained after the PSA type dryer (6,7) .

- a third three-way valve (10) between two PSA type dryers

(6.7) , which allows the system for nitrogen outlet according to order of nitrogen drying process.

4. The system according to claim 1, wherein it comprises piston valves at the dryer exhaust, for discharging the pressure in the tank to the atmosphere in the depressurization step of the regenerated dryer tank.

5. The system of claim 1, 3 or 4, wherein it comprises a software controlling valves within the system sequentially and according to a specific algorithm.

6. The system according to claim 1, wherein it comprises a dew point meter and analyzers for measuring quality of nitrogen gas at inlet and outlet of the system.

7. The system according to claim 1, wherein it comprises a hydrogen flow meter for allowing controlling of hydrogen passage by the PID.

8. The system according to claim 1, wherein it comprises temperature sensors in predetermined zones to measure temperatures of the system. The system according to claim 1, wherein it comprises two valves allowing the passage of hydrogen, one of which is normally closed and the other is a proportional valve that regulates the hydrogen passage. The system according to claim 1, wherein it comprises two compressed air inlets (12) . The system according to claim 1, wherein it comprises a nitrogen inlet (1) for introducing high purity nitrogen gas to the system. The system according to claim 1, wherein it comprises a storage tank (11) for storing nitrogen gas at the outlet of the system. A working method of a system according to any one of the preceding claims, characterized by comprising the steps of;

- providing the passage of compressed air to a second dryer unit at the same time and regenerating as in PSA type dryers for a certain time,

- depressurizing the tanks by opening exhaust piston valves of a second dryer for a certain time while a first tower of a first dryer is still sending dried nitrogen gas to the storage tank (11) ,

16 - then providing the passage of high purity nitrogen gas from the deoxo units to a first tower of a second dryer unit , then depressuri zing the tower for a certain time ,

- providing the passage of compressed air to a first dryer unit at the same time and regenerating as in PSA type dryers for a certain time ,

- then depressuri zing the tank for a certain time with nitrogen gas passing to a second tank of a first dryer,

- then allowing the passage of nitrogen gas to the storage tank ( 11 ) for a certain time , by opening a closed valve located downstream of a second dryer to which nitrogen gas passes ,

- depressuri zing the tanks by opening exhaust piston valves of a second dryer for a certain time while a first tower of a second dryer is still sending dried nitrogen gas to the storage tank,

14 . The method according to claim 13 , wherein i f it is detected from the data obtained from the temperature sensors that the system has exceeded a certain level of temperature , the valve placed for safety for blocking the hydrogen passage and the proportional valve that regulates the hydrogen passage are closed .