CN106978449A - A kind of organic waste anaerobic dry fermentation produces the method and system of bio-natural gas - Google Patents

Abstract

The invention discloses a method and system for producing biological natural gas by anaerobic dry fermentation of organic waste, belonging to the technical field of biomass energy. In this method, organic waste is put into a fermentation bin to produce biogas through anaerobic fermentation reaction, and the biogas is purified and purified to produce Class II natural gas that meets the GB 17820‑2012 standard. The method and system are new and efficient organic waste energy reuse technologies, which have the advantages of short treatment process, large operating flexibility, low energy consumption and clean production, and are especially suitable for agricultural and forestry waste, domestic waste, and kitchen waste. Good market prospects.

Description

A method and system for producing bio-natural gas by anaerobic dry fermentation of organic waste

technical field

The invention discloses a method and system for producing biological natural gas by anaerobic dry fermentation of organic waste, belonging to the technical field of biomass energy.

Background technique

Energy is an important basic resource for the development of human society, but with the development of the world economy, the rapid increase of population and the continuous improvement of people's living standards, the world's energy demand continues to increase, and the three major fossil energy sources (oil, natural gas, coal) are currently The main body of energy consumption, because of its non-renewable characteristics, has led to a severe energy crisis; at the same time, the use of fossil energy has also brought a series of climate and environmental problems. Therefore, the development of renewable and low-carbon energy has become an effective way to optimize the energy structure, realize energy conservation and emission reduction, and protect the ecological environment.

Biogas, as a renewable low-carbon energy source, is a flammable mixed gas mainly composed of methane and low-level calorific value not less than 17MJ/m ³ produced by the digestion of organic matter under anaerobic conditions by microorganisms. The raw materials for biogas production come from a wide range of sources, including agricultural and forestry waste, livestock and poultry manure, sludge, industrial organic waste, domestic waste, kitchen waste, etc. The composition of biogas and bio-natural gas is similar, and the bio-natural gas obtained after purification and purification of biogas can be used as a substitute for natural gas.

At present, China's urban domestic waste has not been effectively sorted and treated, livestock and poultry manure is piled up randomly, and straw is discarded and incinerated on the spot. These problems have become more and more prominent, causing damage to the production and living environment such as the atmosphere, soil and water. The resource utilization of organic waste to produce bio-natural gas through anaerobic fermentation can optimize the national energy structure, reduce greenhouse gas emissions and smog, improve the living environment, and achieve sustainable development of the ecological environment.

Contents of the invention

Aiming at the problems existing in the prior art, the invention provides a method and system for producing bio-natural gas by anaerobic dry fermentation of organic waste.

The purpose of the present invention can be achieved through the following technical solutions:

A method for producing bio-natural gas by anaerobic dry fermentation of organic waste, the method comprising the following steps:

(A) Dry fermentation process: organic waste raw materials and inoculum are mixed and anaerobic fermentation is carried out under the action of anaerobic microorganisms; the biogas produced by anaerobic fermentation is stored in a biogas cabinet after rough desulfurization; The biogas slurry is subjected to sedimentation treatment, and the supernatant after sedimentation is used for circular spraying of the fermentation reaction materials; part of the biogas residue after the fermentation reaction is used for composting to produce solid fertilizer, and the other part is used as inoculum;

(B) Purification and purification process: the biogas from the biogas tank is pressurized and then undergoes fine desulfurization treatment to further remove hydrogen sulfide in the biogas; the biogas after fine desulfurization and the circulating biogas from membrane separation are compressed by the biogas compressor and then cooled Condensation and dehydration; the dehydrated biogas undergoes heat exchange and temperature rise for demist and dust removal; finally, biogas with standard concentration is obtained through gas membrane separation treatment.

In the technical solution of the present invention: the organic waste raw material described in step (A) is one or more of agricultural and forestry waste, livestock and poultry manure, sludge, industrial organic waste residue, domestic garbage and kitchen waste, and the organic waste The mass concentration of dry matter in the raw material is 15-60%.

In the technical solution of the present invention: the time of the fermentation reaction in step (A) is 20-60 days, the temperature of the fermentation reaction is 15-55° C., the pressure of the fermentation reaction is 0-20 kPaG, and the pH value of the fermentation reaction is 6.0-8.0.

Preferably: the time of the fermentation reaction in step (A) is 25-30 days, the temperature of the fermentation reaction is 35-40° C., the pressure of the fermentation reaction is 1.0-5.0 kPaG, and the pH value of the fermentation reaction is 6.8-7.5.

In the technical solution of the present invention: the hydrogen sulfide content of the biogas described in step (A) is reduced to less than 200ppm after crude desulfurization.

In the technical solution of the present invention: in the step (B), the pressure of the biogas after pressurization is 50-200 kPaG; the pressure of the biogas after compression is 1.5-10.0 MpaG.

In the technical solution of the present invention: the hydrogen sulfide content of the biogas after refined desulfurization in step (B) is reduced to less than 15 mg/m ³ ; the temperature of the biogas after cooling is 0-7°C.

A system for producing bio-natural gas through the above-mentioned anaerobic dry fermentation of organic waste, the system includes a fermentation bin, the materials in the mixing area are transported into the fermentation bin, and the output end at the top of the fermentation bin is passed through a crude The desulfurization tower is connected to the biogas tank, an output end at the bottom of the fermentation bin is connected to the biogas slurry storage tank through a biogas slurry tank, and the output end at the bottom of the biogas slurry storage tank is connected to the top of the fermentation bin;

The output end of the biogas cabinet is connected to the biogas compressor through the fine desulfurization tower, and the biogas compressor is connected to the gas condenser, the hot water heater, the mist eliminator and the dust collector in turn, and the output end of the dust collector Connected to the first-stage membrane separator, one output end of the first-stage membrane separator is connected to the bottom of the third-stage membrane separator, and the other output end is connected to the bottom of the second-stage membrane separator; One output at the top of the second-stage membrane separation is biological natural gas, the other output and one output at the top of the third-stage membrane separator are connected to the biogas compressor, and the other output at the top of the third-stage membrane separator The terminal is connected with the fermentation chamber through the carbon dioxide gas holder.

In the above system: part of the material at the bottom of the fermentation bin is transported to the mixing area, and the gas output end at the top of the biogas slurry tank and the output end at the top of the biogas slurry storage tank are connected to the crude desulfurization tower.

In the above system: the output end at the bottom of the biogas slurry storage tank is connected to the top of the fermentation bin through a spray heater.

Beneficial effects of the present invention:

The invention provides a method and system for producing bio-natural gas by anaerobic dry fermentation of organic waste, and the system includes anaerobic dry fermentation technology and purification and purification technology. The use of anaerobic dry fermentation technology to treat organic waste on the one hand improves the resource utilization value and economic value of organic waste, and produces clean renewable energy—biogas; on the other hand, it effectively solves the problems of simple stacking, landfill, and incineration of organic waste. environmental pollution problems. The use of biogas purification and purification technology aims to remove impurity components such as hydrogen sulfide, water, particles, and carbon dioxide in biogas to produce bio-natural gas, so as to achieve high-value utilization of biogas and maximize economic benefits. The invention is a novel and efficient biomass energy utilization technology, which has the advantages of short processing flow, large operation flexibility, low energy consumption and clean production, and is especially suitable for processing agricultural and forestry waste, domestic waste, and kitchen waste, and has a good market prospect .

Description of drawings

Fig. 1 is a kind of flow diagram of the present invention.

Fig. 2 is a schematic structural diagram of a system of the present invention.

In the figure, 1 is the mixing area, 2 is the fermentation bin, 3 is the crude desulfurization tower, 4 is the biogas tank, 5 is the carbon dioxide gas tank, 6 is the biogas slurry tank, 7 is the biogas slurry storage tank, 8 is the biogas slurry pump , 9 is the spray liquid circulation pump, 10 is the spray liquid heater, 11 is the booster fan, 12 is the carbon dioxide replacement fan, 13 is the biogas compressor, 14 is the fine desulfurization tower, 15 is the gas condenser, 16 is the heat Water heater, 17 is a mist eliminator, 18 is a dust collector, 19 is a first-stage membrane separator, 20 is a second-stage membrane separator, and 21 is a third-stage membrane separator.

detailed description

The present invention will be further described below in conjunction with embodiment, but protection scope of the present invention is not limited to this:

A system for producing bio-natural gas by anaerobic dry fermentation of organic waste, the system includes a fermentation bin (2), the materials in the mixing area (1) are transported into the fermentation bin (2), and the fermentation bin (2 ) top output end is connected with the biogas tank (4) through the crude desulfurization tower (3), and an output end at the bottom of the fermentation bin (2) is connected with the biogas liquid storage tank (7) through the biogas slurry tank (6), The output end at the bottom of the biogas slurry storage tank (7) is connected to the top of the fermentation bin (2);

The output end of the biogas cabinet (4) is connected to the biogas compressor (13) through the fine desulfurization tower (14), and the biogas compressor (13) passes through the gas condenser (15), hot water heater ( 16), demister (17) is connected with deduster (18), and the output end of described deduster (18) is connected with first-stage membrane separator (19), and described first-stage membrane separator (19) ) is connected to the bottom of the third-stage membrane separator (21), and the other output is connected to the bottom of the second-stage membrane separator (20); the top of the second-stage membrane separator (20) One output end is biological natural gas, and the other output end and an output end at the top of the third-stage membrane separator (21) are connected with the biogas compressor (13), and the other output end at the top of the third-stage membrane separator (21) One output end is connected with the fermentation chamber (2) through the carbon dioxide gas holder (5). Part of the material at the bottom of the fermentation bin (2) is transported into the mixing area (1), the gas output end at the top of the biogas digester (6) and the output end at the top of the biogas liquid storage tank (7) are connected with the crude desulfurization tower (3 ) connected. The output end at the bottom of the biogas slurry storage tank (7) is connected to the top of the fermentation bin (2) through a spray heater (10).

A method for producing bio-natural gas by anaerobic dry fermentation of organic waste by using the above-mentioned system, the method is specifically as follows:

The pretreated domestic garbage 68461t/a and the inoculum 34231t/a are evenly mixed in the mixing area 1 and then transported to the fermentation bin 2 (the dry matter concentration is 33%). The role of anaerobic microorganisms in the fermentation bin 2 The anaerobic fermentation reaction is carried out, the control operation time is 27 days, the control operation temperature is 38-40°C, the control operation pressure is 4kPaG, and the pH value of the fermentation reaction is 6.8-7.5. The biogas 5050720Nm ³ /a produced by the fermentation reaction (in which the molar content of methane is 55.52%, the molar content of carbon dioxide is 38.52%, the molar content of water vapor is 5.96%, and the molar content of hydrogen sulfide is less than 2000ppm) passes through the crude desulfurization tower 3 to remove a part of hydrogen sulfide to reduce the content of hydrogen sulfide in the biogas to less than 200ppm and then enter the biogas tank 4, the biogas slurry produced in the fermentation reaction enters the biogas slurry tank 6, and the settled supernatant is transported to the biogas slurry storage tank 7 through the biogas slurry pump 8 . The biogas produced in the biogas slurry tank 6 and the biogas slurry storage tank 7 also passes through the crude desulfurization tower 3 to remove a part of hydrogen sulfide and then enters the biogas tank 4, and the biogas slurry in the biogas slurry storage tank 7 is transported to the The spray liquid heat exchanger 10 sprays the materials in the fermentation bin 2 after being heated to maintain the temperature and humidity required for anaerobic fermentation, ensure the number and reproduction speed of the microbial flora in the fermented product, and promote the gas production of the materials in the fermentation bin 2. The biogas residue 62461t/a (dry substance mass concentration is 30%) discharged from fermentation bin 2 is used for aerobic composting to process the production of solid fertilizer, and 34231t/a (dry substance mass concentration is 30%) is used as inoculum and returns to the mixture again. Material area 1.

After the gas volume of the biogas tank 4 reaches a certain gas storage value, the valve is opened. The biogas is pressurized by the booster fan 11 to 100kPaG and then enters the fine desulfurization tower 14 to remove hydrogen sulfide in the biogas. The desulfurizer used in the fine desulfurization tower 14 mainly includes activated carbon or iron oxide. A total of 6,870,880 Nm ³ /a of biogas and circulating biogas from which hydrogen sulfide has been removed (the molar content of methane is 36.00%, the molar content of carbon dioxide is 61.60%, the molar content of water vapor is 2.40%, and the molar content of hydrogen sulfide is less than 15mg/m ³ ). The compressor 13 compresses to 2.0MpaG and enters the gas condenser 15 to cool down to 5°C. The moisture in the biogas is condensed into a liquid of 132.48t/a and discharged. The cooled biogas enters the hot water heater 16 and heats up to 35°C, then passes through the demister in turn 17 and dust collector 18 to filter out trace impurities in the biogas and then enter the membrane separator for three-stage membrane separation treatment. Biogas 6706000Nm ³ /a (the molar content of methane is 36.89%, the molar content of carbon dioxide is 63.11%, and the molar content of hydrogen sulfide is less than 15mg/m ³ ) first enters the first-stage membrane separator 19, and the first-stage retentate gas is 4311680Nm ³ /a (wherein the molar content of methane is 74.04%, the molar content of carbon dioxide is 25.96%, and the molar content of hydrogen sulfide is less than 15mg/m ³ ) enters the second-stage membrane separator 20, and the first-stage permeated gas is 2394320Nm ³ /a (wherein the molar content of methane is 5.65 %, carbon dioxide molar content is 94.35%) into the third-stage membrane separator 21; secondary permeate gas 1293280Nm ³ /a (wherein methane molar content is 20.11%, carbon dioxide molar content is 79.89%) and third-stage retentate gas 526880Nm ³ /a (wherein the molar content of methane is 24.89%, and the molar content of carbon dioxide is 75.11%) is returned to the inlet of biogas compressor 13 as circulating biogas 1820160Nm ³ /a to complete the closed cycle to improve the recovery rate of methane. The secondary retentate gas is 3,018,480 Nm ³ /a of standard natural gas (in which the molar content of methane is 97.14%, and the molar content of carbon dioxide is 2.86%) ^; Mole content is 99.60%) separated carbon dioxide gas part is stored in the carbon dioxide gas tank 5, and when the fermentation bin is opened, it is sent into the fermentation bin through the carbon dioxide replacement fan 12 as the replacement gas before the fermentation bin 2 is opened, and the excess part is sent to Drain in a safe place.

Claims (10)

1. a kind of method that organic waste anaerobic dry fermentation produces bio-natural gas, it is characterised in that：This method includes as follows Step：

(A) dry fermentation process：Organic waste raw material carries out anaerobism hair after being mixed with inoculum in the presence of anaerobe Ferment reacts；The biogas that anaerobic fermentation reaction is produced enters biogas gas holder after thick desulfurization and stored；The natural pond produced in fermentation process Liquid carries out settlement treatment, and the supernatant liquor after sedimentation carries out circulated sprinkling to fermentation reaction material；Biogas residue one after fermentation reaction Part is used as compost treatment and produces solid fertilizer, and another part is used as inoculum；

(B) purification process：The biogas that biogas gas holder comes out carries out fine de-sulfur processing after supercharging and further removed in biogas Hydrogen sulfide；Biogas after fine de-sulfur and the recycled biogas from UF membrane carry out cooling condensation after being compressed through Marsh gas compression machine de- Water；Biogas after dehydration carries out demisting and dedusting after heat exchange heating；Eventually pass gaseous jet simulation processing and obtain normal concentration Bio-natural gas.

2. the method that organic waste anaerobic dry fermentation according to claim 1 produces bio-natural gas, it is characterised in that： Organic waste raw material described in step (A) be agriculture and forestry organic waste material, feces of livestock and poultry, sludge, industrial organic waste residues, house refuse and Dry biomass concentration is 15~60% in one or more in rubbish from cooking, organic waste raw material.

3. the method that organic waste anaerobic dry fermentation according to claim 1 produces bio-natural gas, it is characterised in that： The time of fermentation reaction is 20~60 days in step (A), and the temperature of fermentation reaction is 15~55 DEG C, and the pressure of fermentation reaction is 0 ~20kPaG, the pH value of fermentation reaction is 6.0~8.0.

4. the method that organic waste anaerobic dry fermentation according to claim 3 produces bio-natural gas, it is characterised in that： The time of fermentation reaction is 25~30 days in step (A), and the temperature of fermentation reaction is 35~40 DEG C, and the pressure of fermentation reaction is 1.0~5.0kPaG, the pH value of fermentation reaction is 6.8~7.5.

5. the method that organic waste anaerobic dry fermentation according to claim 1 produces bio-natural gas, it is characterised in that： Hydrogen sulfide content of the biogas after thick desulfurization decreases below 200ppm described in step (A).

6. the method that organic waste anaerobic dry fermentation according to claim 1 produces bio-natural gas, it is characterised in that： Biogas pressure after supercharging is 50~200kPaG in step (B)；Pressure is 1.5~10.0MpaG after Marsh gas compression.

7. the method that organic waste anaerobic dry fermentation according to claim 1 produces bio-natural gas, it is characterised in that： Hydrogen sulfide content of the biogas after fine de-sulfur decreases below 15mg/m in step (B)³；Temperature after biogas cooling is 0~7 ℃。

8. the system that a kind of organic waste anaerobic dry fermentation for being used to realize described in claim 1 produces bio-natural gas, its It is characterised by：

The system includes fermentation cabin (2), and the material of described mixed material area (1) is transported into fermentation cabin (2), fermentation cabin (2) top The output end in portion is connected by thick desulfurizing tower (3) with biogas gas holder (4), and an output end of fermentation cabin (2) bottom passes through Biogas slurry pond (6) is connected with biogas slurry storage tank (7), and the output end of biogas slurry storage tank (7) bottom is connected with the top of fermentation cabin (2)；

The output end of the biogas gas holder (4) is connected by fine de-sulfur tower (14) with Marsh gas compression machine (13), described biogas pressure Contracting machine (13) passes sequentially through gas condenser (15), hot-water heater (16), demister (17) and is connected with deduster (18), described The output end of deduster (18) is connected with first order membrane separator (19), and one of described first order membrane separator (19) exports End is connected with the bottom of third level membrane separator (21), and another output end is connected with second level membrane separator (20) bottom；Institute The output end at the top of second level UF membrane (20) stated is bio-natural gas, another output end and third level membrane separator (21) output end at the top of is connected with Marsh gas compression machine (13), another at the top of described third level membrane separator (21) Output end is connected by carbon dioxide gas holder (5) with fermentation cabin (2).

9. the system that organic waste anaerobic dry fermentation according to claim 8 produces bio-natural gas, it is characterised in that： The partial material of fermentation cabin (2) bottom is transported into gas output end and biogas slurry storage at the top of mixed material area (1), biogas slurry pond (6) Output end at the top of tank (7) is connected with thick desulfurizing tower (3).

10. the system that organic waste anaerobic dry fermentation according to claim 8 produces bio-natural gas, its feature exists In：The output end of biogas slurry storage tank (7) bottom is connected by spray liquid heater (10) with the top of fermentation cabin (2).