Biogas temperature swing and pressure swing adsorption purification system

Abstract

The invention discloses a purification system for temperature and pressure swing adsorption of biogas. The purification system comprises a compressor for pressurizing inlet gas; the air inlet buffer tank is arranged at the output end of the compressor, and a first connecting pipe is arranged at the output end of the air inlet buffer tank; the at least two adsorption towers are respectively connected to the first connecting pipe through a pipeline and a first program control valve, and the two adsorption towers are internally communicated through a second program control valve; the product gas buffer tank is connected to one end of the adsorption tower; through the arrangement of the compressor, the gas inlet buffer tank, the adsorption tower, the product gas buffer tank and the purification assembly, an adsorbent with high adsorption capacity is adopted, so that the impurity adsorption effect is conveniently improved, the purity of biogas is guaranteed, the methane recovery rate is improved, the adsorbent is regenerated in a manner of combining vacuumizing and thermal desorption, and the recovery rate of methane is improved. The adsorbent is regenerated thoroughly and is convenient to recycle, and meanwhile, the recovery rate and the purity of biological methane in the biogas can be improved.

Description

Technical Field

[0001] The invention specifically relates to a biogas purification system using temperature and pressure swing adsorption. Background Art

[0002] Biogas, as a high-quality renewable green biomass energy source, is mainly composed of methane (CH 4 ) and carbon dioxide (CO 2 ) composition, for purifying and separating biogas to obtain biomethane as a supplement to natural gas resources, it can not only alleviate the problem of energy shortage, but also solve part of the problem of agricultural waste, which has very important social, economic and environmental benefits.

[0003] CN105038881B discloses a method for continuous separation of biogas by pressure swing adsorption, which adopts a normal pressure (0.1 MPa) adsorption method to separate carbon dioxide gas from biogas and realize the comprehensive utilization of biogas; reduced pressure vacuum desorption can regenerate the adsorption material; CN110234418A discloses a method for removing H from biogas. 2 S and CO 2 An integrated PTSA / membrane method and system, which uses a PTSA device to adsorb water, VOC and H in biogas 2 S and other impurities, and then CH 4 and CO 2 Separation is performed to obtain product gas that meets natural gas specifications.

[0004] Existing technologies can meet the requirements of methane purification, but there are some shortcomings in actual use. The continuous separation of biogas by pressure swing adsorption has a relatively low operating pressure of 0.1 MPa, resulting in a low recovery rate of methane and poor adsorption effect on impurities in methane, and it is impossible to realize the recovery and reuse of the adsorbent after adsorption. Another method of removing impurities from biogas is to use a PTSA device to adsorb water, VOC and H in biogas. 2 S and other impurities, and then CH 4 and CO 2 Separation is performed to obtain product gas that meets natural gas specifications. In this technology, PTSA is not used to separate CH 4 and CO 2 Instead, membrane separation technology is used, which has complex processes, and the membrane components are easily contaminated, with high investment and short service life. For this reason, we propose a biogas purification system with temperature and pressure swing adsorption. Summary of the invention

[0005] The object of the present invention is to provide a biogas purification system by temperature and pressure swing adsorption to solve the problems raised in the above background technology that the existing methane purification by adsorption at a relatively low pressure has a low recovery rate, it is not convenient to regenerate the adsorbent, and the purification by PTSA / membrane method has a high investment and use cost and requires frequent maintenance.

[0006] To achieve the above object, the present invention provides the following technical solution: a biogas temperature and pressure swing adsorption purification system, comprising:

[0007] A compressor for pressurizing the intake air;

[0008] An air intake buffer tank is arranged at the output end of the compressor, and a first connecting pipe is arranged at the output end of the air intake buffer tank;

[0009] At least two adsorption towers are connected to the first connecting pipe through pipelines and first program-controlled valves respectively, and the two adsorption towers are internally connected through a second program-controlled valve;

[0010] The product gas buffer tank is connected to one end of the adsorption tower;

[0011] The purification component is connected to the adsorption tower to change the temperature and pressure of the adsorbent inside the adsorption tower for regeneration.

[0012] Preferably, the purification component includes a desorption gas buffer tank, a heater, a cooler, a vacuum pump, a second connecting pipe, a third connecting pipe and a fourth connecting pipe. The cooler is connected to one end of the adsorption tower through the second connecting pipe at the lower end, and the output end of the cooler is provided with a vacuum pump. One end of the vacuum pump is respectively connected to the output end of the desorption gas buffer tank and the input end of the compressor through pipelines. One end of the desorption gas buffer tank is connected to the interior of the adsorption tower through the third connecting pipe. The input end of the heater is connected to the lower end of the adsorption tower, and the output end of the heater is connected to a side wall of the adsorption tower through the fourth connecting pipe.

[0013] Preferably, an electric heating wire is arranged inside the heater.

[0014] Preferably, the heating temperature of the heater is 150-260°C.

[0015] Preferably, three output pipes are arranged side by side on one side of the fourth connecting pipe, and the three output pipes are respectively connected to the upper part, the middle part and the lower part of one side wall of the adsorption tower.

[0016] Preferably, the pipeline between the vacuum pump and the compressor input end has a fourth programmable valve.

[0017] Preferably, six adsorption towers are provided.

[0018] Preferably, a fifth connecting pipe communicating with the interior of the adsorption tower for gas reflux is provided on one side of the product gas buffer tank, and a fifth program-controlled valve is installed on the fifth connecting pipe.

[0019] Preferably, the compressor boost pressure range is: 0.6MPa-0.8MPa.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention is provided with a compressor, an air intake buffer tank, an adsorption tower, a product gas buffer tank and a purification component, so as to avoid the conventional separation of biogas by adopting normal pressure operation, which has a relatively low pressure, poor adsorption effect on impurities in methane, and is not convenient for regenerating the adsorbent. On the other hand, the membrane separation technology has a relatively high investment cost, the membrane component is easily contaminated, and has a short service life. The present invention adopts an adsorbent with a high adsorption capacity, which is convenient for improving the adsorption effect on impurities, ensuring the purity of biogas, and improving the methane recovery rate. The adsorbent is regenerated by combining vacuum extraction and thermal desorption, and the adsorbent is completely regenerated for easy reuse. At the same time, the recovery rate and purity of biological methane in biogas can be improved, the content of biological methane in desorbed gas can be reduced, and waste can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the present invention.

[0023] In the figure: 10, compressor; 11, air intake buffer tank; 12, adsorption tower; 13, product gas buffer tank; 14, desorption gas buffer tank; 15, heater; 16, cooler; 17, vacuum pump; 18, first connecting pipe; 19, second connecting pipe; 20, third connecting pipe; 21, fourth connecting pipe; 22, fifth connecting pipe. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] See also Figure 1 The present invention provides a technical solution: a biogas temperature and pressure swing adsorption purification system, comprising:

[0026] A compressor 10 for pressurizing intake air;

[0027] An air intake buffer tank 11 is disposed at the output end of the compressor 10, and a first connecting pipe 18 is disposed at the output end of the air intake buffer tank 11;

[0028] It is convenient to increase the gas pressure so that the adsorbent can better contact with the gas and adsorb and remove impurities in the biogas. The gas pressure is balanced through the air intake buffer tank 11 before entering the adsorption tower 12, reducing large fluctuations in gas pressure after entering the adsorption tower 12.

[0029] At least two adsorption towers 12 are connected to the first connecting pipe 18 through pipelines and first program-controlled valves, and the two adsorption towers 12 are internally connected through a second program-controlled valve;

[0030] The biomethane is retained by removing impurities through an adsorption process.

[0031] The product gas buffer tank 13 is connected to one end of the adsorption tower 12;

[0032] The purification component is connected to the adsorption tower 12 to change the temperature and pressure of the adsorbent inside the adsorption tower 12 for regeneration, so as to improve the regeneration of the adsorbent inside the adsorption tower 12 for reuse.

[0033] Preferably, the purification component includes a desorption gas buffer tank 14, a heater 15, a cooler 16, a vacuum pump 17, a second connecting pipe 19, a third connecting pipe 20 and a fourth connecting pipe 21. The cooler 16 is connected to one end of the adsorption tower 12 through the second connecting pipe 19 at the lower end, and the output end of the cooler 16 has a vacuum pump 17. One end of the vacuum pump 17 is respectively connected to the output end of the desorption gas buffer tank 14 and the input end of the compressor 10 through pipelines. One end of the desorption gas buffer tank 14 is connected to the interior of the adsorption tower 12 through the third connecting pipe 20. The input end of the heater 15 is connected to the lower end of the adsorption tower 12, and the output end of the heater 15 is connected to a side wall of the adsorption tower 12 through the fourth connecting pipe 21.

[0034] After the adsorption process of the adsorption tower 12 is completed, the system will automatically switch to the discharge state through the programmable valve, and the pressure will be released to about 0.05MPa, releasing part of the gas in the adsorption tower 12. The released gas enters another adsorption tower 12 for stamping to help restore the adsorption capacity of the adsorbent. Then, the adsorption tower 12 will further reduce the pressure to 0.02MPa through the programmable valve, and start the vacuum pump 17 to pump the gas pressure in the adsorption tower 12 to -0.09MPa. In this process, the methane and other adsorbed gases inside the adsorption tower 12 are desorbed.

[0035] Preferably, an electric heating wire is provided inside the heater 15 to facilitate rapid heating.

[0036] Preferably, the heating temperature of the heater 15 is 150-260° C., so that the gas inside the adsorption tower 12 can be desorbed better by changing the temperature, so as to facilitate the regeneration of the adsorbent.

[0037] Preferably, three output pipes are arranged side by side on one side of the fourth connecting pipe 21, and the three output pipes are respectively connected to the upper, middle and lower parts of one side wall of the adsorption tower 12, so as to accelerate the desorption process of the adsorbent by the high temperature of the purge gas flow. The purge gas enters from the upper, middle and lower positions of the adsorption tower 12 to ensure the uniformity and efficiency of the heating desorption. The purge gas is discharged from the adsorption tower 12 after being heated, and then enters the cooler 16. After cooling, it is recycled by the vacuum pump 17. This process helps to remove the excess heat generated during the hot purge process, and sends the gas back to the biogas compressor 10 for reprocessing, and then cold blowing is performed. Cold blowing refers to further cooling the adsorption tower 12 by cold air to ensure that the adsorption tower 12 returns to normal temperature and is ready for the next round of adsorption operation.

[0038] Preferably, the pipeline between the vacuum pump 17 and the input end of the compressor 10 has a fourth programmable valve to facilitate controlling the gas entering the compressor 10.

[0039] Preferably, six adsorption towers 12 are provided to facilitate better adsorption effect. At the same time, during stamping and depressurization, multiple adsorption towers 12 are linked to allow the depressurized gas from the adsorption tower 12 to flow into the inside of another adsorption tower 12 to achieve stamping.

[0040] Preferably, a fifth connecting pipe 22 is provided on one side of the product gas buffer tank 13 and is connected to the interior of the adsorption tower 12 for gas reflux. A fifth program-controlled valve is installed on the fifth connecting pipe 22 to provide sufficient pressure to meet the adsorption tower 12's adsorption of impurities in the biogas.

[0041] Preferably, the boosting range of the compressor 10 is: 0.6MPa-0.8MPa, so as to facilitate better adsorption pressure.

[0042] The working principle and use process of the present invention are as follows: when in use, the biogas is pressurized to 0.6-0.8MPa by the biogas compressor 10 and then enters the air intake buffer tank 11, and then is sent to the adsorption tower 12 to obtain the product gas biomethane after adsorption, which is sent out through the product gas buffer tank 13; the adsorption tower 12 that reaches a certain adsorption time releases the pressure to about 0.05MPa through a program-controlled valve, and the released gas enters the remaining adsorption towers 12 to press them, and then is connected to the desorption gas buffer tank 14 through a program-controlled valve to release the pressure in the adsorption tower 12 to 0.02MPa, and then the vacuum pump 17 is started to pump the pressure in the adsorption tower 12 to -0.09MPa. At this time, the desorption gas is sent out after the desorption gas buffer tank 14. After the vacuumization, the adsorption tower 12 is heated by the purge gas through the heater 15, and the vacuumized adsorption tower 12 is further heated and desorbed. The hot purge gas enters the adsorption tower 12 from the upper, middle and lower positions of the adsorption tower 12 to improve the heating efficiency. After the heating and desorption are completed, the purge gas enters the adsorption tower from the upper, middle and lower positions of the adsorption tower 12 for rapid cold blowing. During the thermal desorption of the adsorption tower 12, the purge gas is sent to the inlet of the biogas compressor 10 after passing through the cooler 16 and the vacuum pump 17. After the cold blowing is completed, the adsorption tower 12 receives the pressure relief from the other adsorption towers for its stamping. After the stamping is about 0.3MPa, it is stamped by the product gas to about 0.6-0.8MPa and then normal adsorption is performed to complete a system process. The operating state of the adsorption tower 12 switches back and forth between adsorption, discharge, vacuumization, hot blowing and cold blowing, stamping 1, and stamping 2, and the automatic switching is completed by the programmable valve arranged on the pipeline.

[0043] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A biogas temperature and pressure swing adsorption purification system, characterized in that: include: A compressor (10) for pressurizing intake air; An air intake buffer tank (11) is arranged at the output end of the compressor (10), and a first connecting pipe (18) is arranged at the output end of the air intake buffer tank (11); At least two adsorption towers (12) are connected to the first connecting pipe (18) through pipelines and first program-controlled valves, respectively, and the two adsorption towers (12) are internally connected through a second program-controlled valve; A product gas buffer tank (13) connected to one end of the adsorption tower (12); The purification component is connected to the adsorption tower (12) to change the temperature and pressure of the adsorbent inside the adsorption tower (12) for regeneration and utilization.

2. A biogas temperature and pressure swing adsorption purification system according to claim 1, characterized in that: The purification component comprises a desorption gas buffer tank (14), a heater (15), a cooler (16), a vacuum pump (17), a second connecting pipe (19), a third connecting pipe (20) and a fourth connecting pipe (21); the cooler (16) is connected to one end of the adsorption tower (12) through the second connecting pipe (19) at the lower end, and the output end of the cooler (16) is provided with a vacuum pump (17); one end of the vacuum pump (17) is respectively connected to the output end of the desorption gas buffer tank (14) and the input end of the compressor (10) through pipelines; one end of the desorption gas buffer tank (14) is connected to the interior of the adsorption tower (12) through the third connecting pipe (20); the input end of the heater (15) is connected to the lower end of the adsorption tower (12), and the output end of the heater (15) is connected to a side wall of the adsorption tower (12) through the fourth connecting pipe (21).

3. A biogas temperature and pressure swing adsorption purification system according to claim 2, characterized in that: The heater (15) is provided with an electric heating wire inside.

4. A biogas temperature and pressure swing adsorption purification system according to claim 2, characterized in that: The heating temperature of the heater (15) is 150-260°C.

5. The biogas temperature and pressure swing adsorption purification system according to claim 2, characterized in that: Three output pipes are arranged side by side on one side of the fourth connecting pipe (21), and the three output pipes are respectively connected to the upper part, the middle part and the lower part of a side wall of the adsorption tower (12).

6. A biogas temperature and pressure swing adsorption purification system according to claim 2, characterized in that: The pipeline between the vacuum pump (17) and the input end of the compressor (10) is provided with a fourth program-controlled valve.

7. The biogas temperature and pressure swing adsorption purification system according to claim 1, characterized in that: Six adsorption towers (12) are provided.

8. The biogas temperature and pressure swing adsorption purification system according to claim 1, characterized in that: A fifth connecting pipe (22) is provided on one side of the product gas buffer tank (13) and is connected to the interior of the adsorption tower (12) for gas reflux. A fifth program-controlled valve is installed on the fifth connecting pipe (22).

9. The biogas temperature and pressure swing adsorption purification system according to claim 1, characterized in that: The pressure boosting range of the compressor (10) is 0.6 MPa-0.8 MPa.

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