CN116078100A - A hydrogen-rich tail gas recovery device and recovery method - Google Patents

Abstract

The invention relates to a hydrogen-rich tail gas recovery device which comprises a cooler, a buffer tank, a compressor, a liquid separating tank, at least one catalytic reaction tower, a heater and a pressure reducing device, wherein the buffer tank is connected with the heater; the catalytic reaction device comprises a cooler I, a buffer tank, a compressor and a liquid separating tank, wherein the cooler I, the buffer tank, the compressor and the liquid separating tank are sequentially communicated, the catalytic reaction towers are connected in parallel, the outlets of the liquid separating tanks are respectively communicated with respective inlets of the catalytic reaction towers, the respective outlets of the catalytic reaction towers output pure hydrogen obtained after purification, the pure hydrogen pipeline is branched into two paths, inlet pipelines at the bottom of the catalytic reaction towers are respectively communicated with a cooler II, and the cooler II is communicated with a booster fan for conveying waste gas to an incineration system. The device is provided with a plurality of layers of filling bins in the catalytic reaction tower, can process raw material gases with different components and provides high-hydrogen purity.

Description

A hydrogen-rich tail gas recovery device and recovery method

technical field

The invention relates to a tail gas treatment technology in the chemical industry, in particular to a hydrogen-rich tail gas recovery device and a recovery method.

Background technique

In the process of chemical production, some waste gas, waste liquid and waste residue will inevitably be produced. In recent years, the issue of energy consumption has been raised to a new level by the national energy department. In order to reduce energy consumption, chemical companies will find ways to use waste gas, waste liquid, and waste residue to eat up energy and minimize operation. energy consumption. During the production process of a chemical plant, a kind of waste gas will be continuously generated. The content of hydrogen in the waste gas is 70%, the content of nitrogen is 12%, the content of methane is 12%, the content of water is 2%, the content of toluene is 0.5%, and the content of cyclohexane The content of cyclohexene is 0.5%, the content of cyclohexene is 0.6%, and the content of carbohydrates is 2.4%. If it is discharged directly, it does not meet the environmental protection requirements. If it is sent to the hydrogen user enterprise, the hydrogen purity is not enough, so the tail gas can only be sent to the torch for incineration. The chemical plant produces exhaust gas of 1200Nm3 per hour. Calculated according to the hydrogen market price of 1.4 yuan/Nm3, 1176 yuan of hydrogen will be burned in one hour. Calculated according to the normal operation of 8000 hours per year, 9.408 million yuan will be burned a year, resulting in a waste of resources. waste and loss of business economy.

Commonly used hydrogen recovery and purification methods include pressure swing temperature swing adsorption, cryogenic separation and membrane separation;

① Cryogenic separation uses the difference in relative volatility of each component in the raw material to separate hydrogen. Due to the low cryogenic temperature, the investment and operating costs are high.

②Membrane separation recovers hydrogen through high pressure, and the recovery rate is high, but the pressure head loss is large, the input cost is high, and it has not been popularized.

③ The hydrogen recovery rate of pressure swing temperature swing adsorption can reach more than 90%, and the purity of hydrogen gas is relatively high, so it is widely used. However, the current pressure swing temperature swing adsorption generally has a low adsorption efficiency, generally about 96%. The adsorption tower of the core adsorption equipment is a fatigue vessel, and special qualifications are required for design and production, which is not easy to promote. The structure of the adsorption tower is single, and there are few kinds of adsorbents that can be filled. The gas distribution in the adsorption tower is not uniform, there is a bias flow phenomenon, and the use efficiency of the adsorbent is low. The gas at the outlet of the adsorption tower is easy to entrain adsorbent particles, which affects the purity of the product hydrogen. Ordinary pressure swing temperature swing adsorption devices can treat a single type of tail gas, that is, if different types of tail gas are processed, different tail gas treatment systems need to be selected, and the on-site equipment is diverse, which increases operating costs and occupies a larger site.

Contents of the invention

In order to solve the problems of low efficiency and poor hydrogen purification effect of the above-mentioned hydrogen-rich tail gas recovery equipment, the present invention provides a hydrogen-rich tail gas recovery device, which is equipped with multi-layer packing bins in the catalytic reaction tower, which can process raw material gases of different components. The technical scheme adopted is as follows:

A hydrogen-rich tail gas recovery device, including a cooler, a buffer tank, a compressor, a liquid separation tank, at least one catalytic reaction tower, a heater and a decompression device;

The cooler I, the buffer tank, the compressor and the liquid separation tank are connected in sequence, and the catalytic reaction towers are connected in parallel, and the outlets of the liquid separation tanks are respectively connected to the respective inlets of the catalytic reaction towers, and the catalytic reaction towers are connected to each other. The respective outlets output purified pure hydrogen and the pure hydrogen pipeline is branched into two paths, one of which is output to the outside of the device for use, and the other pure hydrogen pipeline returns to the catalytic reaction through the heater and decompression device The respective outlets of the towers enter into the towers; the pipes at the inlets at the bottom of the catalytic reaction towers are respectively connected to the cooler II, and the cooler II is connected with a booster fan for transporting the waste gas to the incineration system.

In the above-mentioned hydrogen-rich tail gas recovery device, the catalytic reaction tower is vertical, and the lower part is the inlet, and the upper part is the outlet; the inlet end is equipped with a gas cone-shaped distributor, and the top surface of the distributor is a flat gas port, and the side is inclined. breath.

In the above-mentioned hydrogen-rich tail gas recovery device, five layers of adsorbent filling bins are arranged in the catalytic reaction tower.

In the above-mentioned hydrogen-rich tail gas recovery device, each layer of the adsorbent filling chamber is provided with a quick loading and unloading port; the quick loading and unloading port is located on the side of the tower body, and N lateral cross-section U-shaped grooves are arranged on the tower body at the quick loading and unloading port. The fast loading and unloading opening is sealed with a circular partition, and N matching gaps that can be clamped and placed on the partition are provided on the partition.

In the above-mentioned hydrogen-rich tail gas recovery device, the outlet of the catalytic reaction tower is provided with an outlet collector, and the outlet collector includes a horizontal top plate and a vertical collection tube, and the top plate is a flange structure to be connected to the outlet of the tower body , the top of the collection tube is screwed to the bottom surface of the top plate for disassembly and cleaning, the bottom of the collection tube is equipped with a sealed bottom plate, and the side of the bottom of the collection tube is evenly provided with a number of through holes and two layers of plain weave screens are laid. The plain weave screen is semi-cylindrical, and the upper and lower ends are fixedly connected by hoop bolts.

In the above-mentioned hydrogen-rich tail gas recovery device, the five-layer catalyst of the adsorbent filling chamber is arranged from bottom to top: activated alumina capable of adsorbing water, Na-Y molecular sieve capable of adsorbing carbon dioxide, and Ca-A/Na catalyst capable of adsorbing methane -X molecular sieve, LiX molecular sieve that can adsorb nitrogen, and 302-activated carbon that can adsorb carbohydrates.

The present invention also relates to a method for recovering hydrogen-rich tail gas, comprising the following steps:

S1) Tail gas is used as raw material gas and enters cooler I through pipeline connection to cool to 20°C;

S2) The cooled raw material gas enters the buffer tank, and then enters the compressor, which pressurizes the raw material gas with a pressure of 20KPa (G) to 0.5MPa, and the temperature of the raw gas at this time is 40°C;

S3) The compressed raw material gas enters the liquid separation tank, and then the gas phase enters the catalytic reaction tower, and the hydrogen purity of the finished product gas exported after the catalytic treatment reaches more than 99.9%;

S4) Lead the product hydrogen, which accounts for about 25% of the outlet of the catalytic reaction tower, to the heater to 160°C, and then reduce the pressure to 20KPa through the decompression device, enter the tower from the outlet of the catalytic reaction tower for regeneration; the exhaust gas after blowing off is downward Enter the cooler II from the entrance below the catalytic reaction tower to cool down to 40°C, and then pass through the booster fan and enter the incineration system for incineration.

In the above step S4, the catalytic reaction tower is provided with two catalytic reaction A towers and catalytic reaction B towers, one of which is catalytically absorbed and the other is regenerated.

The beneficial effects of the present invention are:

First, the device and process can treat industrial production tail gas containing more than 70% hydrogen. By selecting and effectively combining adsorbents, the hydrogen content of the treated tail gas can be as high as 99.9%, reaching the standard for direct use by hydrogen-using enterprises.

Second, the catalytic reaction tower is equipped with multi-layer adsorbent packing bins, which are convenient for loading and unloading, and different adsorbents are selected according to different raw material gases, which can handle raw material gases under different working conditions, and the tower body is a conventional pressure vessel, which does not require special design qualifications , The equipment has a long service life and low cost.

Third, the frustum-shaped distributor of the catalytic reaction tower has good gas passage and uniform distribution, which prevents gas deviation and makes the utilization rate of the adsorbent ideal. The collector at the outlet of the catalytic reaction tower effectively collects the fine particles of the adsorbent to ensure the purity of the product hydrogen.

Description of drawings

Fig. 1 is the system schematic diagram of the recovery device of the embodiment of the invention;

Fig. 2 is the structural representation of catalytic reaction A tower/catalytic reaction B tower of the embodiment of the present invention;

Fig. 3 is the schematic structural diagram of the inlet distributor of catalytic reaction A tower/catalytic reaction B tower of the embodiment of the present invention;

Fig. 4 is the top view structure diagram of the inlet distributor of catalytic reaction A tower/catalytic reaction B tower of the embodiment of the present invention;

Fig. 5 is the schematic diagram of the cross-sectional structure of the fast loading port on the catalytic reaction A tower/catalytic reaction B tower of the embodiment of the present invention;

Fig. 6 is a schematic diagram of the front structure of the quick loading port on the catalytic reaction A tower/catalytic reaction B tower of the embodiment of the present invention;

Fig. 7 is the structural schematic diagram of the outlet collector on the catalytic reaction A tower/catalytic reaction B tower of the embodiment of the present invention;

Fig. 8 is a schematic plan view of the integration of the recovery device according to the embodiment of the present invention.

In the figure: 1—cooler I, 2—buffer tank, 3—compressor, 4—separation tank, 5—catalytic reaction tower A, 6—catalytic reaction tower B, 7—heater, 8—decompression device, 9—cooler Ⅱ, 10—supercharger fan,

2-1—inlet distributor, 2-2—adsorbent filling bin, 2-3—exit collector, 2-4—quick loading and unloading port,

5-1—block, 5-2—partition, 5-3—handle,

6-1—collection tube, 6-2—hoop, 6-3—plain screen, 6-4—fixed steel wire, 6-5—bottom plate.

Detailed ways

The technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings. It should be emphasized that the following embodiments are exemplary, and all technical and scientific terms used therein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

In the following embodiments, various pipelines, valves, pumps and other components are required for the connection between devices, all of which are in the usual form in the field, and the use of the above components is not a structure for improving the technical problems of this application. Those skilled in the art can effectively connect or communicate components such as coolers, etc., using various pipelines, valves, pumps, etc. under the guidance of the prior art and accompanying drawing 1.

This embodiment is a recovery device for hydrogen-rich tail gas, including a cooler 1, a buffer tank 2, a compressor 3, a liquid separation tank 4, a catalytic reaction A tower 5, a catalytic reaction B tower 6, a heater 7 and a reducing Pressure device 8.

The cooler I1, the buffer tank 2, the compressor 3 and the liquid separation tank 4 are connected in sequence, the catalytic reaction A tower 5 and the catalytic reaction B tower 6 are connected in parallel, and the outlets of the liquid separation tank 4 are respectively connected The respective inlets of the catalytic reaction A tower 5 and the catalytic reaction B tower 6, the respective outlets of the catalytic reaction A tower 5 and the catalytic reaction B tower 6 output purified pure hydrogen obtained after purification and the pure hydrogen pipeline is branched into two paths, wherein One pure hydrogen pipeline is output to the outside of the device for use, and the other pure hydrogen pipeline returns to the respective outlets of the catalytic reaction A tower 5 and the catalytic reaction B tower 6 through the heater 7 and the decompression device 8 . The inlet pipes at the bottom of the catalytic reaction A tower 5 and the catalytic reaction B tower 6 are respectively connected to the cooler II9, and the cooler II9 is connected with a booster fan 10 for transporting the waste gas at the bottom of the tower to the incineration system.

Both the catalytic reaction A tower 5 and the catalytic reaction B tower 6 are vertical, and the internal and external structures of the two towers are exactly the same. The tower body is made of steel shell, the upper and lower parts use EHA elliptical heads, the middle is a cylindrical steel cylinder, and the adsorbent packing is placed in the tower.

Conventional adsorption towers are generally fatigue equipment due to frequent pressure fluctuations during operation. Fatigue equipment generally has the following disadvantages: 1. The service life is short. Taking the pressure rise and fall of the fatigue equipment as a cycle, and the pressure cycle is 2000 times, the fatigue equipment will reach the design life and need to be remade. The service life of the equipment is generally 7 years; 2. The stress condition of the fatigue equipment is complex, and the stress concentration is easy to form at the welding seam of the equipment opening, and the stress concentration is easy to occur within the design life of the equipment, resulting in the rupture of the equipment; 3. The fatigue equipment The design of pressure vessels requires special qualifications, which are more stringent than ordinary pressure vessels, and the design cycle is long and the cost is high. In this embodiment, the catalytic reaction A tower 5 and the catalytic reaction B tower 6 are designed to increase the design pressure of the equipment to more than 5 times the maximum working pressure, and are designed and manufactured with conventional pressure vessels. The design service life can reach more than 20 years, and the equipment life is increased by nearly 3 times. ; After the design pressure is increased, the possibility of partial rupture of the equipment due to stress concentration is eliminated, and the operation of the equipment is safer and more stable.

The lower part of the catalytic reaction A tower 5 and the catalytic reaction B tower 6 are all inlets, and the upper part is an outlet. As shown in Figure 3 and Figure 4, a gas frustum-shaped distributor is arranged at the inlet end, and the top surface of the distributor is a plane, and the side surface is The inclined setting forms a conical frustum as a whole. After being simulated by the FLUNT flow field simulation software, the gas distribution into the tower can be made more uniform. The top of the distributor is covered with a plain weave screen and the gas passing rate of the screen is 98.5%, which avoids the phenomenon of gas deviation. Thereby improving the use efficiency of the adsorbent.

Both the catalytic reaction A tower 5 and the catalytic reaction B tower 6 are equipped with five layers of adsorbent filling bins 2-2, and each layer of adsorbent filling bins 2-2 is equipped with a quick loading and unloading port, which is convenient for the overall loading and replacement of the adsorbent. As shown in Figure 6, the fast loading and unloading port is located at the side of the tower body, and N stoppers 5-1 with U-shaped grooves in the lateral cross section are set on the tower body at the fast loading and unloading port, and a circular dividing plate 5 -2 to seal the fast loading and unloading port, and set N gaps that can be stuck on the matching block 5-1 on the partition plate 5-2. During installation, the gaps on the partition plate 5-2 are correspondingly stuck on the block 5 -1, the size of the notch is larger than the block 5-1, hold the handle 5-3 to rotate the partition 5-2, and the edge of the partition 5-2 will slide into the U-shaped groove of the block 5-1, thereby fixing the partition Plate 5-2.

The outlets of the catalytic reaction A tower 5 and the catalytic reaction B tower 6 are respectively provided with an outlet collector 2-3, as shown in Figures 2 and 7, the outlet collector 2-3 includes a horizontally arranged top plate and a vertical The collection tube 6-1, the top plate is a flange structure so as to be connected to the outlet of the tower body, the top of the collection tube 6-1 is screwed to the bottom surface of the top plate for disassembly and cleaning, and the bottom of the collection tube 6-1 is installed with Sealed bottom plate 6-5, the side of the lower part of the collection tube 6-1 is evenly provided with a number of through holes and two layers of plain weave screen 6-3 are laid, the plain weave screen 6-3 is semi-cylindrical, and the upper and lower ends are covered with The hoops are fixedly connected, and the mesh surface of the plain weave screen 6-3 is bound and fixed on the collection cylinder 6-1 with steel wires. The outlet collector 2-3 is convenient for disassembly, cleaning and replacement of the screen, which is convenient for equipment maintenance. The clean hydrogen obtained after the catalytic reaction is discharged smoothly, and the adsorbent with small particles is trapped in the tower.

The system structure of the recovery device can realize modular design, manufacture and installation. As shown in Figure 8, the schematic layout of the device is a box structure as a whole. The lower right corner of the box is the entrance and exit of the operator, the A port on the left side of the box is the raw material gas inlet, and the B port is the product pure hydrogen outlet. Port C is the exhaust gas incineration outlet. When using it, you only need to connect ports A, B and C to the corresponding external pipes. On the left side of the box, V-101 buffer tank 2, V-102 liquid separation tank 4, T-101B catalytic reaction tower B 6, T-101A catalytic reaction tower A 5 and booster fan 10 are arranged from bottom to top. The side is provided with C-101 compressor 3, E-101 cooler I1, E-102 heater 7 and E-103 cooler II9 from bottom to top. After the whole set of device can be manufactured and installed, it can be hoisted to the use site as a whole. In this way, the construction time and site occupation at the site of use can be greatly saved, and the normal production at the site of use will hardly be affected. After the modularization, the reasonable layout of the device reduces the amount of piping materials and reduces the internal resistance of the system. The periphery of the box can be sealed with sound-proof cotton and fixed iron sheets, which can reduce the noise transmission of the C-101 compressor and make the maintainability and operability of the device the best.

In this embodiment, 1000Nm ³ /h module, 3000Nm ³ /h module, 5000Nm ³ /h module and other modules for different processing capacity are produced, and the corresponding fixed module can be selected according to the flow rate of raw material gas to be processed, which saves a lot of Time-consuming in early stage design, production, scheme selection, etc.

For example, a user in a production enterprise has two similar exhaust gas generating systems, but the amount of exhaust gas produced is different, one is 1000Nm ³ /h, and the other is 2000Nm ³ /h. According to the flow rate of the raw material gas, select two sets of recovery devices corresponding to this embodiment. The layout and pipeline direction of each recovery device are the same, but the size of the recovery devices is different. The modularization is provided and used. The user only needs to It is simple and quick to connect the reserved ABC three nozzles on site.

The recovery device and process can process industrial production tail gas with a hydrogen content of more than 70%, and the hydrogen purity after treatment can reach more than 99.9%, with strong processing capacity and high efficiency. ASPEN PLUS is used for PFD simulation of the whole process flow, and the equipment selection and energy utilization of each process are optimized to minimize equipment investment and operating energy consumption.

Embodiment one

The tail gas produced by the cyclohexanone production unit has a temperature of about 160°C and a pressure of 20KPa (G), in which the hydrogen content is 70%, the nitrogen content is 12%, the methane content is 12%, the water content is 2%, toluene The content is 0.5%, the content of cyclohexane is 0.5%, the content of cyclohexene is 0.6%, and the content of carbohydrates is 2.4%.

Tail gas is used as raw material gas and enters cooler Ⅰ1 through pipeline connection to cool down to 20°C;

The cooled raw gas enters the buffer tank 2, and then enters the compressor 3, and the compressor 3 pressurizes the raw gas with a pressure of 20KPa (G) to 0.5MPa, and the temperature of the raw gas is about 40°C at this time;

The compressed raw material gas will be mixed with a small amount of liquid and enter the liquid separation tank 4. After preliminary gas-liquid separation in the liquid separation tank 4, the gas phase enters the catalytic reaction A tower 5 and the catalytic reaction B tower 6 for advanced treatment. The purity of hydrogen in the medium is over 99.9%;

The product hydrogen, which accounts for about 25%, is led to the heater 7 to 160 °C, and then the pressure is reduced to 20KPa by the decompression device 8, and then the catalytic reaction tower A 5 and the catalytic reaction tower B 6 are respectively catalyzed from the opposite direction, and the catalysis and absorption modules are carried out. regeneration. One tower of catalytic reaction A tower 5 and catalytic reaction B tower 6 absorbs, the other tower regenerates, and recycles, so that the raw material gas can be processed continuously and efficiently;

The blown off gas goes downward from the inlets below the catalytic reaction A tower 5 and the catalytic reaction B tower 6 and enters the cooler II 9 to cool down to 40°C, and then passes through the booster fan 10 and enters the incineration system for incineration.

According to the composition characteristics of the feed gas, the adsorbent filling chambers in tower 5 of catalytic reaction A and tower 6 of catalytic reaction select activated alumina (which has a good adsorption effect on water) and 303-activated carbon (p-toluene, ring Hexane and cyclohexene have good adsorption), Ca-A/Na-X molecular sieves (good adsorption for methane), LiX molecular sieves (good adsorption for nitrogen), 302-activated carbon (good for carbohydrates have good adsorption), the loading order of these five adsorbents cannot be changed arbitrarily. According to the composition of the raw material gas, the removal of water in the raw material gas is the first priority. Although the activated carbon and other adsorbents used later have a good adsorption effect on organic substances such as toluene, they can also absorb water. Assuming that the activated carbon is loaded on the bottom layer, because The ability to adsorb organic substances such as toluene will be reduced if water is adsorbed, which will eventually affect the purification effect of raw gas. Similarly, the adsorption capacity of 303-activated carbon to toluene, cyclohexane and cyclohexene is better than that of Ca-A/Na-X molecular sieve, LiX molecular sieve and 302-activated carbon. Play the strongest adsorption capacity. 302-activated carbon has a good adsorption effect on carbohydrates due to its own microporous structure, and also has a good adsorption effect on organic substances such as toluene and cyclohexene, so it is placed in the last layer of the raw material gas adsorption process as a The final adsorbent for raw gas adsorption, if there is unadsorbed escape gas, will be captured by 302-activated carbon in the last layer to further ensure the purity of the product gas. In this way, water, toluene/cyclohexane/hexene, methane, nitrogen, and carbohydrates are removed in sequence. The purity of the final exported gas hydrogen is over 99.9%, which can be sent to the hydrogen production device for direct use.

In this embodiment, the recovery device can recover 630Nm3 pure hydrogen per hour. Calculated according to the hydrogen market price of 1.4 yuan/Nm3, 882 yuan of hydrogen will be recovered per hour. Calculated according to the normal operation of 8000 hours per year, the annual increase will be 7.056 million yuan benefit. A total of 5.57 million yuan has been invested in equipment and civil engineering, and the annual energy consumption of public works such as steam, water, and electricity consumption has increased by 1.06 million yuan. It is expected that the cost will be recovered in 12 months and profits will be realized.

Embodiment two

The composition of the tail gas in this example is different from Example 1. The hydrogen content is 70%, the nitrogen content is 11.7%, the methane content is slightly higher at 14%, the water content is lower at 0.5%, the carbon monoxide content is 0.3%, and the carbon dioxide content is 3.5% %.

The process is the same as in Example 1: tail gas enters cooler I1, buffer tank 2, compressor 3, liquid separation tank 4, catalytic reaction A tower 5 and catalytic reaction B tower 6 through pipelines for advanced treatment, and the purity of the finished product hydrogen at the outlet is It reaches more than 99.9%; the product hydrogen, which accounts for about 25%, is led to the heater 7, and through the decompression device 8, the catalytic reaction A tower 5 and the catalytic reaction B tower 6 are respectively reversed to regenerate the catalytic and absorption modules; The exhaust gas after removal enters the cooler II from the entrance below the catalytic reaction A tower 5 and the catalytic reaction B tower 6, then passes through the booster fan 10, and enters the incineration system for incineration.

The difference from Example 1 is that the adsorbent filling bins in the catalytic reaction A tower 5 and the catalytic reaction B tower 6 of this embodiment select activated alumina from bottom to top according to the composition characteristics of the raw material gas (good for water). adsorption), Na-Y molecular sieve (good adsorption for carbon dioxide), Ca-A/Na-X molecular sieve (good adsorption for methane), LiX molecular sieve (good adsorption for nitrogen), 302- Activated charcoal (good adsorption on carbohydrates).

Comparative example one

This comparative example deals with the tail gas with the same composition as in Example 1, that is, the tail gas temperature is about 160°C, the pressure is 20KPa (G), and the hydrogen content is 70%, the nitrogen content is 12%, the methane content is 12%, and the water content is 2%, the toluene content is 0.5%, the cyclohexane content is 0.5%, the cyclohexene content is 0.6%, and the carbohydrate content is 2.4%.

In this comparative example, two sets of catalytic reaction towers are used for simultaneous adsorption but no catalytic regeneration scheme is adopted, that is, there is no way that one tower is regenerated and the other tower is adsorbed. The catalytic reaction tower is equipped with 3 layers of adsorbents, which are activated alumina from bottom to top. Balls (3mm in diameter, used to absorb moisture), 303-activated carbon, 302-activated carbon, and the content comparison of each component of the finished gas are shown in the table below.

Comparative example two

This comparative example deals with the tail gas of the same composition as Example two, that is, the hydrogen content is 70%, the nitrogen content is 11.7%, the slightly higher methane content is 14%, the water content is 0.5%, the carbon monoxide content is 0.3%, and the carbon dioxide content is 3.5%. %.

This comparative example uses a group of catalytic reaction towers, which are equipped with 5 layers of adsorbents, from bottom to top are activated alumina balls (3mm in diameter, used to absorb water), silica gel, 303-activated carbon, zeolite molecular sieve, 302 - Activated carbon, the content comparison of each component of the product gas is shown in the table below.

Comparative example three

This comparative example deals with the tail gas of the same composition as Example two, that is, the hydrogen content is 70%, the nitrogen content is 11.7%, the slightly higher methane content is 14%, the water content is 0.5%, the carbon monoxide content is 0.3%, and the carbon dioxide content is 3.5%. %.

The adsorbent and arrangement thereof of this comparative example and embodiment two are all the same, and the process flow is the same but the pressure of the compressor 3 and the temperature rise data of the heater 7 are different, specifically:

The raw material gas enters the cooler Ⅰ1 through pipeline connection and cools down to 20°C;

The cooled raw gas enters the buffer tank 2, and then enters the compressor 3, and the compressor 3 pressurizes the raw gas to 0.25MPa, and the temperature of the raw gas is about 30°C;

The compressed raw material gas enters the liquid separation tank 4, and after preliminary gas-liquid separation in the liquid separation tank 4, the gas phase enters the catalytic reaction A tower 5 and the catalytic reaction B tower 6 for advanced treatment, and the hydrogen purity in the finished product gas at the outlet is 97 %about;

Lead the product hydrogen, which accounts for about 25%, to the heater 7 to 120°C, and after the pressure is reduced to the initial pressure of the raw material gas through the decompression device 8, the catalytic reaction A tower 5 and the catalytic reaction B tower 6 are respectively carried out from the opposite direction. Regeneration of catalytic and absorption modules. One of the catalytic reaction A tower 5 and the catalytic reaction B tower 6 absorbs and the other regenerates. The adsorbent of this embodiment is affected by the temperature change of the system, the regeneration time is prolonged by 20%, the adsorption effect is reduced by 30%, and the life of the adsorbent is reduced by 25%. Although the operating energy consumption is reduced, the overall effect is not worth the candle.

From the above-mentioned Example 1, Example 2 and Comparative Example 1, Comparative Example 2, the proportion of each component in the product gas, the device cost and energy consumption.

Compared with Comparative Example 1, Example 1 uses two layers of activated carbon, but nitrogen, methane, and carbohydrates in the finished gas of Example 1 are still dozens of times less than those in Comparative Example 1. Therefore, the multilayer adsorbent The layout of the gas has a great influence on the composition of the product gas. The catalytic reaction tower of the recovery device in Example 1 adopts a cycle operation of regeneration and adsorption in the other, which improves the service life of the catalytic adsorbent and the efficiency of hydrogen recovery and treatment, saves a lot of operating costs and reduces coal consumption.

Embodiment 2 Compared with Comparative Example 2, the contents of nitrogen, methane, carbon dioxide and carbon monoxide in the product gas of Embodiment 2 are greatly reduced. Embodiment 2 Compared with Comparative Example 3, Embodiment 2 increases the pressure and the temperature of the heater 7 through the compressor 3, so that the efficiency in the liquid separation, catalytic adsorption, catalytic regeneration and other processes is improved, equipment maintenance is reduced, and operation is saved cost. Compared with Comparative Example 1 and Comparative Example 2, the content of nitrogen, methane and carbohydrates in Comparative Example 2 is lower, indicating that the multi-layer catalysts in the catalytic reaction tower can only reduce impurities in the product gas to a small extent. The type of adsorbent and the layering sequence can improve the hydrogen purity of the product gas.

Claims (8)

1. The utility model provides a rich hydrogen tail gas recovery unit which characterized in that: comprises a cooler (1), a buffer tank (2), a compressor (3), a liquid separating tank (4), at least one catalytic reaction tower, a heater (7) and a pressure reducing device (8);

the cooler I (1), the buffer tank (2), the compressor (3) and the liquid separating tank (4) are sequentially communicated, the catalytic reaction towers are connected in parallel, the outlets of the liquid separating tank (4) are respectively communicated with the respective inlets of the catalytic reaction towers, the respective outlets of the catalytic reaction towers output purified pure hydrogen, the pure hydrogen pipeline is branched into two paths, one path of pure hydrogen pipeline is output to the outside of the device for use, and the other path of pure hydrogen pipeline returns to the respective outlets of the catalytic reaction towers through the heater (7) and the pressure reducing device (8) and enters the tower; the inlet pipeline at the bottom of the catalytic reaction tower is respectively communicated with a cooler II (9), and the cooler II (9) is communicated with a booster fan (10) for conveying waste gas to the incineration system.

2. The hydrogen-rich tail gas recovery apparatus according to claim 1, wherein: the catalytic reaction tower is vertical, the lower part is provided with an inlet, and the upper part is provided with an outlet; the inlet end is provided with a gas frustum-shaped distributor, the top surface of the distributor is a plane gas port, and the side surface of the distributor is a gas port which is obliquely arranged.

3. The hydrogen-rich tail gas recovery apparatus according to claim 1, wherein: five layers of adsorbent filling bins (2-2) are arranged in the catalytic reaction tower.

4. A hydrogen rich tail gas recovery apparatus according to claim 3, wherein: each layer of adsorbent filling bin (2-2) is provided with a quick loading and unloading port; the rapid loading and unloading port is positioned at the side part of the tower body, N stop blocks (5-1) with U-shaped grooves in lateral cross sections are arranged on the tower body at the rapid loading and unloading port, the rapid loading and unloading port is sealed by a round partition plate (5-2), and the partition plate (5-2) is provided with N matched notches capable of clamping the stop blocks (5-1).

5. The hydrogen-rich tail gas recovery apparatus according to claim 1, wherein: the outlet of the catalytic reaction tower is provided with an outlet collector (2-3), the outlet collector (2-3) comprises a horizontally arranged top plate and a vertical collecting cylinder (6-1), the top plate is of a flange structure and is connected to the outlet of the tower body, the top of the collecting cylinder (6-1) is screwed to the bottom surface of the top plate so as to be convenient to disassemble and clean, the bottom of the collecting cylinder (6-1) is provided with a sealed bottom plate (6-5), the side surface of the lower part of the collecting cylinder (6-1) is uniformly provided with a plurality of through holes and lays two layers of plain screens (6-3), the plain screens (6-3) are semi-cylindrical, and the upper end and the lower end of the plain screens are fixedly connected by hoop screws.

6. A hydrogen rich tail gas recovery apparatus according to claim 3, wherein: five layers of catalysts of the adsorbent filling bin (2-2) are arranged from bottom to top as follows: activated alumina capable of adsorbing water, na-Y molecular sieve capable of adsorbing carbon dioxide, ca-A/Na-X molecular sieve capable of adsorbing methane, liX molecular sieve capable of adsorbing nitrogen and 302-activated carbon capable of adsorbing carbohydrate.

7. The hydrogen-rich tail gas recovery method is characterized by comprising the following steps of:

s1) tail gas is used as raw material gas and is connected with a cooler I (1) through a pipeline to be cooled to 20 ℃;

s2) feeding the cooled raw material gas into a buffer tank (2), and then feeding the cooled raw material gas into a compressor (3), wherein the compressor pressurizes the raw material gas with the pressure of 20KPa (G) to 0.5MPa, and the temperature of the raw material gas is 40 ℃;

s3) the compressed raw material gas enters a liquid separating tank (4), then the gas phase enters a catalytic reaction tower, and the purity of the hydrogen of the finished product gas at an outlet after catalytic treatment reaches more than 99.9%;

s4) introducing product hydrogen with the outlet of the catalytic reaction tower accounting for about 25% of the outlet of the catalytic reaction tower to the temperature of between the heater (7) and 160 ℃, and then reducing the pressure to 20KPa through a pressure reducing device (8) to enter the catalytic reaction tower from the outlet of the catalytic reaction tower for regeneration; the blown off waste gas enters a cooler II (9) from the inlet below the catalytic reaction tower downwards to be cooled to 40 ℃, and then enters an incineration system to be incinerated through a booster fan (10).

8. The hydrogen-rich tail gas recovery method according to claim 7, wherein: in the step S4, two catalytic reaction towers, namely a catalytic reaction tower a (5) and a catalytic reaction tower B (6), are provided, wherein one tower is used for catalytic absorption and the other tower is used for regeneration.

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