Biogas purification method and device based on vacuum freezing technology
阅读说明：本技术 一种基于真空冷冻技术的沼气净化提纯方法及装置 (Biogas purification method and device based on vacuum freezing technology ) 是由 牛晓君 肖华平 郭华芳 唐志华 刘敏茹 张荔 张冬青 李霞 于 2020-04-20 设计创作，主要内容包括：本发明公开了一种基于真空冷冻技术的沼气净化提纯方法及装置,属于可再生能源利用技术领域。本发明通过真空冷冻技术对沼气进行压缩冷冻净化提纯,不需外加化学试剂,整个净化提纯过程中几乎不产生废物,分离得到的硫化氢、CO<Sub>2</Sub>可以进行再利用,节能环保,同时,通过对净化提出后的沼气中主要杂质的含量进行检测,提纯后的沼气浓度可达到98％以上,应用本发明的技术得到的甲烷产品纯度高,适合推广；本发明的沼气净化提纯装置通过缓存检测箱与外部输气管连接处设有泄露检测元件,当缓存检测箱与外部输气管连接处发生泄漏时,进行及时检测,并将检测结果发送至远程监控模块,便于及时发现泄漏尽早处理,避免发生事故。(The invention discloses a method and a device for purifying methane based on a vacuum freezing technology, and belongs to the technical field of renewable energy utilization. The invention carries out compression, refrigeration, purification and purification on the methane by a vacuum refrigeration technology without adding chemical reagents, almost no waste is generated in the whole purification and purification process, and hydrogen sulfide and CO obtained by separation 2 The method has the advantages that the method can be reused, energy is saved, the environment is protected, meanwhile, the concentration of the purified methane can reach more than 98% by detecting the content of main impurities in the purified methane, and the methane product obtained by applying the technology of the invention has high purity and is suitable for popularization; according to the biogas purification device, the leakage detection element is arranged at the joint of the cache detection box and the external gas pipe, so that when the joint of the cache detection box and the external gas pipe leaks, the detection is carried out in time, and the detection result is sent to the remote monitoring module, so that the leakage can be found out in time and processed as early as possible, and accidents are avoided.)
1. A biogas purification method based on vacuum freezing technology is characterized by mainly comprising the following steps:
(1) pretreatment: filtering untreated crude biogas to remove dust and solid impurities in the crude biogas to obtain pretreated biogas;
(2) purifying: firstly, pumping the pretreated biogas obtained in the step (1) into a compressor, pressurizing to 10-13Bar, pumping the pressurized biogas into a vacuum freeze dryer, freeze-drying for 15-25min at the freezing temperature of-8-3 ℃, removing water in the biogas, pumping the dried biogas into a heat exchanger, reducing the temperature to-20 to-15 ℃, and keeping for 25-30min to ensure that part of H in the biogas is2S、NH3Condensing and separating out liquid H through a gas-liquid separator2S、NH3Condensation and methane separation are carried out, and simultaneously, separated liquid H is treated2S and NH3Recycling is carried out;
(3) and (3) purification: pumping the purified marsh gas into a compressor, pressurizing to 20-25Bar, pumping the pressurized marsh gas into a vacuum freeze dryer again, freeze-drying for 15-25min at a freezing temperature of-20 to-15 ℃, re-drying the marsh gas, pumping the dried marsh gas into a heat exchanger, reducing the temperature to-55 ℃, keeping the temperature for 35-45min, and pumping CO in the marsh gas2Condensing and separating out liquid CO through a gas-liquid separator2Separating the biogas from the biogas to obtain the finally purified biogas, and recycling the precipitated liquid carbon dioxide;
(4) and (3) finished product detection: and (3) storing the biogas obtained in the step (3), detecting the final purity of the biogas by a detection instrument, if the purity of the processed biogas is qualified, reserving the biogas, if the purity of the processed biogas is unqualified, pumping the biogas into the compressor in the step (2) again, and reprocessing the biogas until the purity of the biogas is qualified.
2. The method for purifying and purifying biogas based on vacuum freezing technology as claimed in claim 1, wherein during the purity detection of biogas in step (4), H in biogas is detected by a hydrogen sulfide concentration detector2The concentration of S is detected by a dissolved oxygen detector to the content of dissolved oxygen in the biogas, and CO in the biogas is detected by a carbon dioxide detector2Detecting when the dissolved oxygen content is 0.05-0.10 mg/L, H2S concentration is less than 10mg/m3，CO2The concentration is 8g/m3And (3) discharging, otherwise, pumping into the compressor in the step (2) again, and treating again until the purity of the methane is qualified.
3. The device for purifying and purifying the biogas based on the vacuum freezing technology, which is used in the method according to claim 1, is characterized by mainly comprising a temporary storage box (1) for storing untreated crude biogas and internally provided with a filter element (10), a compressor (2) for pressurizing the biogas pretreated by the temporary storage box (1), a vacuum freeze dryer (3) for freeze-drying the pressurized biogas and removing moisture, a heat exchanger (4) for exchanging heat and reducing the temperature of the gas treated by the vacuum freeze dryer (3), a gas-liquid separator (5) connected with the heat exchanger (4), a buffer detection box (6) connected with the gas-liquid separator (5) and the compressor (2), an intelligent control device (7) and a power supply electrically connected with each electrical element;
one-way solenoid valves (9) are arranged between the temporary storage box (1) and the compressor (2), between the compressor (2) and the vacuum freeze dryer (3), between the vacuum freeze dryer (3) and the heat exchanger (4), between the heat exchanger (4) and the gas-liquid separator (5), between the gas-liquid separator (5) and the buffer detection box (6) and between the buffer detection box (6) and the compressor (2);
the cache detection box (6) is provided with a device for detecting H in the biogas2A hydrogen sulfide concentration detector (60) for detecting the concentration of S, a dissolved oxygen detector (61) for detecting the content of dissolved oxygen in the biogas, and a detector for detecting CO in the biogas2A carbon dioxide detector (62) for detecting carbon dioxide;
the intelligent control device (7) comprises a controller (70) for controlling each electrical element to normally operate, an electronic pressure gauge (71) for detecting the methane pressure, a thermometer (72) for detecting the methane temperature and a humidity detection sensor (73) for detecting the liquid in the methane.
4. The biogas purification device based on vacuum freezing technology as claimed in claim 3, wherein the upper end of the temporary storage tank (1) is provided with a cover plate (11) and an air inlet (12), the upper end of the cover plate (11) is provided with a hook ring (110) connected with an external hoisting device, the lower end of the cover plate (11) is provided with a hydraulic cylinder (111), the filtering element (10) is horizontally arranged on the inner wall of the temporary storage tank (1), and the upper end of the filtering element (10) is connected with the bottom end of the hydraulic cylinder (111) through a connecting rope.
5. The biogas purification device based on vacuum freezing technology as claimed in claim 4, the device is characterized in that the filtering piece (10) comprises a mounting and fixing frame (100) fixedly arranged on the inner wall of the temporary storage box (1) and a plurality of filtering grids (101) which can be clamped on the mounting and fixing frame (100) and are uniformly distributed from top to bottom, the number of the filtering grids (101) is sequentially increased, each side edge of each filtering grid (101) is hinged with a rotating expansion plate (1010), the bottom end of each rotating expansion plate (1010) is provided with a splicing and fixing column (1011), the rotary expansion plates (1010) at the corresponding side edges of the filtering grids (101) are connected with the bottom end of the hydraulic cylinder (111) through connecting lines, clamping frames (1000) are arranged on the mounting fixed frame (100) at the positions corresponding to the rotary expansion plates (1010), each side wall of the clamping frame (1000) is provided with an inserting groove (1001) corresponding to the inserting fixing column (1011).
6. The biogas purification device based on vacuum freezing technology as claimed in claim 3, wherein the sidewall of the temporary storage tank (1) is provided with an access opening (13), and an access ladder (130) is arranged at the access opening (13).
7. The biogas purification device based on the vacuum freezing technology as claimed in claim 3, wherein a leakage detection element (63) is arranged at the joint of the buffer detection box (6) and the external gas pipe, the leakage detection element (63) comprises a detection buckle cover (630) which is arranged at the joint of the buffer detection box (6) and the external gas pipe and a detection hole (631) which is arranged on the side wall of the detection box, a sealing cover (6310) is arranged outside the detection hole (631), a pressure sensor (632) which is arranged on the detection buckle cover (630), a mounting rack (633) which is arranged in the detection hole (632), a micro blade (634) the center of which is connected with the mounting rack (633) through a rotating shaft, and a rotation speed sensor (635) which is arranged at the center of the rotating blade (634).
Technical Field
The invention belongs to the technical field of renewable energy utilization, and particularly relates to a biogas purification method and device based on a vacuum freezing technology.
Background
The biogas is a precious green energy with great development potential, and is generated in different environments, such as refuse landfills, sewage sludge and anaerobic fermentation of organic substances in biological waste, so that the biogas can be generated, and in addition, the resources for generating biogas in rural areas are very rich. The biogas is a combustible mixed gas, and the main component is CH4、CO2Small amount of H2S、H2、O2、CO、N2And the like.
Biogas is a mixed gas produced by the fermentation of organic substances under anaerobic conditions. Biogas, as the name implies, is the gas in a marsh, and people often see that bubbles emerge from the marsh, sewage ditch or septic tank, and if you scratch a match, it can be ignited, which is the naturally occurring biogas in nature, and since this gas is first found in the marsh, it is called biogas. Various organic matters such as human and animal excreta, straws, sewage and the like are fermented in a closed methane tank under the anaerobic (oxygen-free) condition and decomposed and converted by a plurality of methane fermentation microorganisms, thereby generating methane.
The biogas is purified mainly by H in the biogas2S、H2O、CO2The removal and purification mixed with halogenation are aimed at preventing corrosion of equipment and so on, and the purification of marsh gas is mainly to remove CO in marsh gas2The purpose of removal and purification is to improve the heat value of the biogas, the biogas purification and purification can realize the efficient utilization of biogas resources, so that the biogas can replace petrochemical fuel gas and be used as vehicle fuel, scattered residential district gas supply or directly connected with a natural gas pipe network and the like, and the purification and purification technology of the biogas mainly comprises a physical absorption method, a chemical absorption method and the likeChemical absorption, pressure swing adsorption, membrane separation, cryogenic separation, and the like.
The invention utilizes the vacuum freezing technology to purify the marsh gas, has the same principle with the cryogenic separation method, and can solve the problem that the prior art purifies the purified marsh gas by hydrogen sulfide and CO2The content of can not detect one by one, make the marsh gas concentration after the purification low, the not good problem of purification effect, moreover, current marsh gas purification equipment can not detect the problem of revealing of taking place between marsh gas storage pool and the outside gas-supply pipe, takes place the incident easily, simultaneously, still can not carry out remote control and control, problem that intelligent degree is low.
Disclosure of Invention
Aiming at the technical problems in the prior art, the invention provides a safe and reliable biogas purification method and device based on a vacuum freezing technology, which have high purification purity and are energy-saving and environment-friendly.
The technical scheme of the invention is as follows: a biogas purification method based on vacuum freezing technology mainly comprises the following steps:
(1) pretreatment: filtering untreated crude biogas to remove dust and solid impurities in the crude biogas to obtain pretreated biogas;
(2) purifying: firstly, pumping the pretreated biogas obtained in the step (1) into a compressor, pressurizing to 10-13Bar, pumping the pressurized biogas into a vacuum freeze dryer, freeze-drying for 15-25min at the freezing temperature of-8-3 ℃, removing water in the biogas, pumping the dried biogas into a heat exchanger, reducing the temperature to-20 to-15 ℃, and keeping for 25-30min to ensure that part of H in the biogas is2S、NH3Condensing and separating out liquid H through a gas-liquid separator2S、NH3Condensation and methane separation are carried out, and simultaneously, separated liquid H is treated2S and NH3Recycling is carried out;
(3) and (3) purification: pumping the purified marsh gas into a compressor, pressurizing to 20-25Bar, and pumping the pressurized marsh gas into vacuum againFreeze-drying at-20-15 deg.C for 15-25min, drying again, pumping into heat exchanger, cooling to-55-55 deg.C, maintaining for 35-45min, and collecting CO in biogas2Condensing and separating out liquid CO through a gas-liquid separator2Separating the biogas from the biogas to obtain the finally purified biogas, and recycling the precipitated liquid carbon dioxide;
(4) and (3) finished product detection: and (3) storing the biogas obtained in the step (3), detecting the final purity of the biogas by a detection instrument, if the purity of the processed biogas is qualified, reserving the biogas, if the purity of the processed biogas is unqualified, pumping the biogas into the compressor in the step (2) again, and reprocessing the biogas until the purity of the biogas is qualified.
Further, when the purity of the biogas in the step (4) is detected, detecting H in the biogas by a hydrogen sulfide concentration detector2The concentration of S is detected by a dissolved oxygen detector to the content of dissolved oxygen in the biogas, and CO in the biogas is detected by a carbon dioxide detector2Detecting when the dissolved oxygen content is 0.05-0.10 mg/L, H2S concentration is less than 10mg/m3，CO2The concentration is 8g/m3And (3) discharging, otherwise, pumping into the compressor in the step (2) again, re-processing until the purity of the biogas is qualified, and performing accurate detection on the content of each impurity gas in the purified and extracted biogas to ensure that the concentration of the purified biogas can reach more than 98%, so that the purification efficiency is high.
The method is used for a biogas purification device based on a vacuum freezing technology, and mainly comprises a temporary storage box for storing untreated crude biogas and internally provided with a filter element, a compressor for pressurizing the biogas pretreated by the temporary storage box, a vacuum freeze dryer for freeze-drying the pressurized biogas and removing water, a heat exchanger for exchanging heat and reducing temperature of the gas treated by the vacuum freeze dryer, a gas-liquid separator connected with the heat exchanger, a cache detection box connected with the gas-liquid separator and the compressor, an intelligent control device and a power supply electrically connected with each electrical element;
one-way solenoid valves are arranged between the temporary storage box and the compressor, between the compressor and the vacuum freeze dryer, between the vacuum freeze dryer and the heat exchanger, between the heat exchanger and the gas-liquid separator, between the gas-liquid separator and the cache detection box and between the cache detection box and the compressor;
the cache detection box is provided with a device for detecting H in the biogas2Detector for detecting concentration of hydrogen sulfide in S, instrument for measuring dissolved oxygen content in biogas, and instrument for measuring CO in biogas2A carbon dioxide detector for detecting;
the intelligent control device comprises a controller for controlling each electrical element to normally operate, an electronic pressure gauge for detecting the pressure of the methane, a thermometer for detecting the temperature of the methane and a humidity detection sensor for detecting liquid in the methane.
Further, the case upper end of keeping in is equipped with the apron and goes into the gas port, just the apron upper end is equipped with the shackle of being connected with outside equipment of lifting by crane, and the apron lower extreme is equipped with the pneumatic cylinder, filter the level and locate the incasement wall of keeping in, and filter the piece upper end and be connected with the pneumatic cylinder bottom through connecting the rope, filter dust and solid impurity in to the coarse marsh gas through filtering, when filtering a needs clearance, lift by crane equipment through the outside and catch on the shackle, open the apron, simultaneously, will filter the piece through the compression of pneumatic cylinder and take out from the incasement of keeping in, and operation or clearance are convenient, easy to use.
Furthermore, the filtering element comprises a fixed mounting frame fixedly arranged on the inner wall of the temporary storage box, a plurality of filtering grids which are uniformly distributed from top to bottom and are sequentially increased in number, each side edge of each filtering grid is hinged with a rotating expansion plate, the bottom end of each rotating expansion plate is provided with a plug-in fixing column, the rotating expansion plate at the corresponding side edge of each filtering grid is connected with the bottom end of the hydraulic cylinder through a connecting line, the fixed mounting frame is provided with a clamping frame corresponding to each rotating expansion plate, each side wall of the clamping frame is provided with a plug-in groove corresponding to the plug-in fixing column, the connecting line on each rotating expansion plate of each filtering grid is driven to be pulled upwards through the upward compression of the hydraulic cylinder, so that each rotating expansion plate corresponding to each filtering grid covers the filtering grid, and solid magazines on the filtering grids are prevented from falling to the temporary storage box in the upward pulling process, causing pollution of the temporary storage box and increasing the cleaning difficulty.
Furthermore, the side wall of the temporary storage box is provided with an access hole, the access hole is provided with an access ladder, and when the internal elements of the temporary storage box are damaged, the internal elements enter the temporary storage box through the access ladder and the access hole, so that the normal operation of the subsequent process can be ensured.
Furthermore, a leakage detection element is arranged at the joint of the cache detection box and the external gas pipe, the leakage detection element comprises a detection buckle cover which is arranged at the joint of the cache detection box and the external gas pipe and is provided with a detection hole on the side wall, a sealing cover is arranged outside the access hole, a pressure sensor arranged on the detection buckle cover, a mounting frame arranged in the detection hole, a miniature blade of which the center is connected with the mounting frame through a rotating shaft, and a rotating speed sensor arranged at the center of the rotating blade, when the connection part of the buffer detection box and the external gas transmission pipe leaks, the micro blade rotates under the action of the airflow in the detection buckle cover, at the moment, the rotating speed sensor detects the rotating speed value, meanwhile, the pressure sensor detects the pressure in the buckle cover, when the pressure is gradually increased, the leakage is indicated, and at the moment, when the pressure is larger, the sealing cover can be opened to release the pressure.
Furthermore, the intelligent control device further comprises a wireless communication module, a remote controller connected with the controller through the wireless communication module, and a remote monitoring module for shooting the running condition of each electrical element, the working personnel can directly carry out remote operation on each device through the remote controller through the connection of the wireless communication module, and meanwhile, the video of the running condition of each device can be remotely observed according to the remote monitoring module, so that the intelligence of the whole biogas purification device is improved, the operation is convenient, and the running is reliable.
The working principle of the purification device is as follows:
(1) raw methane is led into a temporary storage box, the raw methane passes through filtering grids with different mesh numbers from top to bottom, dust and solid impurities in the raw methane are removed, pretreated methane is obtained, when a filtering piece needs to be cleaned, a hook ring is hooked through external hoisting equipment, a cover plate is opened, meanwhile, a hydraulic cylinder is compressed upwards to drive connecting wires on rotating expansion plates of each filtering grid to be pulled upwards, the corresponding rotating expansion plates on each filtering grid wrap the filtering grid, solid magazines on the filtering grids are prevented from falling into the temporary storage box in the process of pulling upwards, after the filtering piece is taken out, each filtering grid is cleaned and then placed into the temporary storage box again, and when elements in the temporary storage box are damaged, the raw methane enters the temporary storage box through an overhauling ladder and an overhauling port;
(2) pumping the pretreated marsh gas into a compressor, pressurizing to 10-13Bar, pumping the pressurized marsh gas into a vacuum freeze dryer, freeze-drying at-8-3 deg.C for 15-25min to remove water in the marsh gas, pumping the dried marsh gas into a heat exchanger, reducing the temperature to-20-15 deg.C, and maintaining for 25-30min to make part of H in the marsh gas2S、NH3Condensing and separating out liquid H through a gas-liquid separator2S、NH3Condensation and methane separation are carried out, and simultaneously, separated liquid H is treated2S and NH3Recycling is carried out;
(3) pumping the purified marsh gas into a compressor, pressurizing to 20-25Bar, pumping the pressurized marsh gas into a vacuum freeze dryer again, freeze-drying at-15- -20 deg.C for 15-25min, drying again, pumping the dried marsh gas into a heat exchanger, reducing the temperature to-55- -35 deg.C, maintaining for 35-45min, and collecting CO in the marsh gas2Condensing and separating out liquid CO through a gas-liquid separator2Separating the biogas from the biogas to obtain the finally purified biogas, and recycling the precipitated liquid carbon dioxide;
(4) introducing the biogas obtained in the step (3) into a cache detection box, and detecting H in the biogas by a hydrogen sulfide concentration detector2The concentration of S is detected by a dissolved oxygen detector to the content of dissolved oxygen in the biogas, and CO in the biogas is detected by a carbon dioxide detector2Detecting when the dissolved oxygen content is 0.05-0.10mg/L，H2S concentration is less than 10mg/m3，CO2The concentration is 8g/m3The biogas can be discharged, otherwise, the biogas is pumped into the compressor in the step (2) again and is reprocessed until the purity of the biogas is qualified, when the connection part of the cache detection box and the external gas pipe leaks, the airflow inside the detection buckle cover acts to enable the miniature blade to rotate, at the moment, the rotating speed sensor detects the rotating speed value, meanwhile, the pressure sensor detects the pressure inside the detection buckle cover, when the pressure is gradually increased, the leakage is indicated, at the moment, when the pressure is higher, the sealing cover can be opened for pressure relief;
(5) in the process, the controller is connected with the remote controller through the wireless communication module, a worker can directly carry out remote operation on each device through the remote controller, and meanwhile, the remote monitoring module can be used for remotely observing the video of the running condition of each device.
The invention has the beneficial effects that: the invention provides a biogas purification method and a biogas purification device based on a vacuum freezing technology, which have the following advantages:
(1) the invention carries out compression refrigeration purification and purification on the methane by a vacuum refrigeration technology, applies a physical separation principle in the purification process, does not need to add chemical reagents, hardly generates waste in the whole purification process, and separates the obtained hydrogen sulfide and CO2The method can be reused, is energy-saving and environment-friendly, and simultaneously, the concentration of the purified methane can reach more than 98% by detecting the content of main impurities in the purified methane.
(2) According to the biogas purification device, dust and solid impurities in the crude biogas are filtered through the filtering pieces, when the filtering pieces need to be cleaned, the upward compression of the hydraulic cylinder drives the connecting lines on the rotating expansion plates of each filtering grid to be pulled upwards, so that the corresponding rotating expansion plates on each filtering grid wrap the filtering grids, and therefore solid magazines on the filtering grids are prevented from falling to the temporary storage box in the upward pulling process, the temporary storage box is prevented from being polluted, and the cleaning difficulty is increased.
(3) According to the biogas purification device, the leakage detection element is arranged at the joint of the cache detection box and the external gas pipe, so that when the joint of the cache detection box and the external gas pipe leaks, the detection is carried out in time, and the detection result is sent to the remote monitoring module, so that the leakage can be found out in time and processed as early as possible, and accidents are avoided.
(4) In the process of purifying the methane, the methane purifying device provided by the invention has the advantages that the staff can directly remotely operate each device through the remote controller through the connection of the wireless communication module, and can remotely observe the running condition video of each device according to the remote monitoring module, so that the intelligence of the whole methane purifying device is increased, the operation is convenient, and the running is reliable.
Drawings
FIG. 1 is a schematic structural diagram of a biogas purification device according to the present invention;
FIG. 2 is a schematic view of the installation of the filter of the present invention in a holding tank;
FIG. 3 is an enlarged view of the invention at A in FIG. 2;
FIG. 4 is a schematic drawing of the hydraulic cylinder of the present invention in its extended configuration;
FIG. 5 is a schematic view of the installation of the leak detection unit of the present invention on a cache detection box;
FIG. 6 is an enlarged view of B of FIG. 5 in accordance with the present invention;
fig. 7 is an electrical connection diagram of the present invention.
Wherein, 1-temporary storage box, 10-filter element, 100-mounting fixed frame, 1000-clamping frame, 1001-inserting groove, 101-filtering grid, 1010-rotating expansion plate, 1011-inserting fixed column, 11-cover plate, 110-shackle, 111-hydraulic cylinder, 12-air inlet, 13-maintenance opening, 130-maintenance ladder, 2-compressor, 3-vacuum freeze dryer, 4-heat exchanger, 5-gas-liquid separator, 6-buffer detection box, 60-hydrogen sulfide concentration detector, 61-dissolved oxygen detector, 62-carbon dioxide detector, 63-leakage detection element, 630-detection buckle cover, 631-detection hole, 6310-seal cover, 632-pressure sensor, 633-mounting frame, 634-miniature blade, 635-rotating speed sensor, 7-intelligent control device, 70-controller, 71-electronic pressure gauge, 72-thermometer, 73-humidity detection sensor, 74-wireless communication module, 75-remote controller, 76-remote monitoring module, 9-one-way solenoid valve.
Detailed Description