Equipment for producing nitrogen fertilizer by using anaerobic fermentation biogas slurry

Abstract

The utility model discloses equipment for producing nitrogen fertilizer by utilizing anaerobic fermentation biogas slurry and relates to the field of organic waste treatment. The device comprises a negative pressure heating stripping tower (1), a kettle type reactor (2), a water storage container (3), a vacuum pump (4), a water pump (5), a circulating fan (6), a heat exchanger (8), a waste gas pipe (12), a waste gas loop (13), a first ball valve (14), a second ball valve (15), a nitrogen fertilizer outlet (17), an ascending pipe (18), a cooling pipe (18) (connected with a cooling system), a first loop pipeline ball valve (20), a second loop pipeline ball valve (21), a third loop pipeline ball valve (22) and a heat exchange pipe (24). The method comprises the following steps: cooling escaped gas CO2 and NH3, introducing the cooled escaped gas CO2 and NH3 into an adsorbent for full absorption so as to form a nitrogen fertilizer, pumping back and discharging unabsorbed residual gas such as CO2 or / and ammonia gas into a container, and a negative pressure system consists of a vacuum pump and a pipeline. And ammonia gas can be circularly absorbed and utilized again in different forms.

Description

Technical Field

[0001] The utility model relates to the field of organic waste treatment, in particular to a device for producing nitrogen fertilizer by anaerobic fermentation of biogas slurry. Background Art

[0002] China has a vast territory and many environmental protection projects, among which the waste biogas slurry from anaerobic fermentation projects is very abundant. Anaerobic fermentation biogas slurry is rich in carbon, nitrogen, phosphorus and other substances. There has been a long period of research on the production of nitrogen fertilizer from organic waste such as anaerobic fermentation biogas slurry, livestock and poultry feces, river sludge or sewer sludge. These research technologies can reduce the production of odorous substances and harmful gases, especially NH3, in the production process of organic fertilizer. However, many technologies cannot effectively reduce the emission of organic waste. The purpose of this utility model is to produce high-quality nitrogen fertilizer through an economical and simple method, while reducing the emission of waste gases such as ammonia, converting waste liquid into environmentally friendly, hygienic and harmless sludge, and reducing the emission of organic waste. CN116751086A discloses a method for preparing fertilizer based on anaerobic fermentation biogas slurry, the method for preparing fertilizer based on anaerobic fermentation biogas slurry comprises dissolving nitrogen fertilizer, phosphate fertilizer and potash fertilizer in water to obtain a composite fertilizer aqueous solution; the composite fertilizer aqueous solution is mixed with anaerobic fermentation biogas slurry to obtain the fertilizer. The utility model draws on the idea of ​​preparing compound fertilizer aqueous solution from biogas slurry, and on this basis combines the stripping process to cyclically absorb carbon dioxide and ammonia in the biogas slurry to prepare nitrogen fertilizer. Utility Model Content

[0003] The utility model aims to provide a set of anaerobic fermentation biogas slurry treatment and nitrogen fertilizer production device to solve the anaerobic fermentation biogas slurry discharge problem mentioned in the above background technology. The utility model can effectively reduce the loss and waste of anaerobic fermentation biogas slurry in the process of producing nitrogen fertilizer by anaerobic fermentation biogas slurry. Ammonia can be fully absorbed after multiple circulation treatments, thereby increasing the output of nitrogen fertilizer.

[0004] A device for producing nitrogen fertilizer by anaerobic fermentation of biogas slurry, characterized in that it comprises a negative pressure heating stripping tower (1), a kettle reactor (2), a water storage container (3), a vacuum pump (4), a water pump (5), a circulating fan (6), a heat exchanger (8), an exhaust pipe (12), an exhaust loop (13), a first ball valve (14), a second ball valve (15), a nitrogen fertilizer outlet (17), a rising pipe (18), a cooling pipe (18) (connected to a cooling system), a first loop pipeline ball valve (20), a second loop pipeline ball valve (21), a third loop pipeline ball valve (22), and a heat exchange pipe (24);

[0005] The cooling pipe (18) is located in the water storage container (3); the heat exchange pipe (24) is located in the negative pressure heating stripping tower (1);

[0006] The hot water outlet pipe (10) of the water storage container (3) is connected to one end of the heat exchange pipe (24) via a first ball valve (14), and the water storage container (3) is also provided with an outlet connected to the one end of the heat exchange pipe (24) via a second ball valve (15), and the other end of the heat exchange pipe (24) is connected to the hot water return pipe (11) of the water storage container (3) via a water pump (5);

[0007] The negative pressure heating stripping tower (1) is provided with an anaerobic fermentation sludge feed port (9), a slag discharge port (16) at the bottom, and a gas outlet at the top; the gas outlet is connected to one end of a waste gas pipe (12) via a riser (18) and a cooling pipe (19) in sequence, and the other end of the waste gas pipe (12) extends into the absorbent of the autoclave reactor (2); the autoclave reactor (2) is filled with a calcium sulfate solution absorbent, the upper part of the autoclave reactor (2) is connected to a vacuum pump (4), and the upper part of the autoclave reactor (2) is also provided with a waste gas circulation outlet, and the waste gas circulation outlet is connected to one end of a waste gas loop (13). A circulating fan (6) is provided on the waste gas loop (13). The other end of the waste gas loop (13) is divided into three branches. One branch is connected to the inlet end of the cooling pipe (19) via a first loop pipeline ball valve (20) and enters the cooling pipe (19) together with the gas coming out of the riser (18) and then enters the kettle reactor (2). The second branch is connected to the gas space at the top of the negative pressure heating stripping tower (1) via a second loop pipeline ball valve (21). The third branch is connected to the liquid space at the bottom of the negative pressure heating stripping tower (1), i.e., the anaerobic fermentation slurry, via a third loop pipeline ball valve (22).

[0008] The kettle reactor (2) is of a conical structure, and a nitrogen fertilizer outlet (17) is provided at the bottom. The nitrogen fertilizer outlet (17) is provided with a shut-off valve (23).

[0009] The kettle reactor (2) is also provided with a calcium sulfate solution adding device.

[0010] The utility model is to heat the anaerobic fermentation slurry to between 40 and 90°C under negative pressure, and then cool the escaped gases CO2 and NH3, and pass them into the adsorbent for full absorption, thereby forming nitrogen fertilizer, and the unabsorbed residual gases such as CO2 and / or ammonia are pumped back and discharged into the container, wherein the negative pressure system is composed of a vacuum pump and a pipeline. Preferably, the unabsorbed gases such as CO2 and / or ammonia will be pressurized and passed into the stripping tower for circulation; optionally, they can also be passed into the anaerobic fermentation slurry to be treated; optionally, they can also be directly stored above the anaerobic fermentation slurry to be treated; optionally, the waste gas can be passed into the gas cooling system above to treat it. Ammonia can be recycled and reabsorbed in different forms. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1The invention shows a device for producing nitrogen fertilizer from anaerobic fermentation biogas slurry, wherein 1-negative pressure heating stripping tower; 2-kettle reactor; 3-water storage container of heat exchanger; 4-vacuum pump; 5-water pump; 6-circulating fan; 7-mixer; 8-heat exchanger; 9-anaerobic fermentation biogas slurry feed port; 10-hot water outlet pipe; 11-hot water return pipe; 12-waste pipe; 13-waste loop; 14-first ball valve; 15-second ball valve; 16-slag outlet; 17-nitrogen fertilizer outlet; 18-rising pipe; 19-cooling pipe (connected to cooling system); 20-first loop pipeline ball valve; 21-second loop pipeline ball valve; 22-third loop pipeline ball valve; 23-shutoff valve, 24-heat exchange pipe. DETAILED DESCRIPTION

[0012] The present invention is further described in detail below in conjunction with the accompanying drawings and technical solutions, but the present application is not limited to the following embodiments.

[0013] Example 1

[0014] The device (its structural diagram is shown in Figure 1 )Select batch mode to run.

[0015] At the feed inlet (9), new anaerobic fermentation sludge is introduced into the negative pressure heating stripping tower (1). After all the sludge enters the stripping tower, the hot water in the hot water circulation system is heated in the water storage container (3) with the heat exchanger (8), and then flows out through the top hot water outlet pipe (10). At this time, the ball valve (14) is opened and the ball valve (15) is closed. The hot water heated to a temperature of about 80°C enters the stripping tower (1) through the hot water outlet pipe for heat exchange, and then passes through the reflux pipe (11) and the water pump (5) to be sent to the heat exchanger (8) again. After the water circulation system reaches the working temperature, the pressure is adjusted in the entire gas circulation system through the vacuum pump (4), and the pressure is slowly and steadily reduced to 40KPa. When the pressure reaches the required level, the circulating fan (6) starts to work. The fan (6) is connected to the autoclave reactor (2) and the waste gas loop (13). The waste gas is extracted from the stripping tower (1) through the waste gas separation pipe (12) at a fixed flow rate. Then, the reflux waste gas from the autoclave reactor (2) passes through the waste gas loop (13) and enters the stripping tower (1) again. The ball valves (20) (21) (22) to be used are described in three scenarios below:

[0016] 1. The ball valve (21) is opened, and the ball valves (20) and (22) are closed. Then all the circulating gas passes through the anaerobic fermentation slurry into the stripping tower (1);

[0017] 2. The ball valve (21) is closed, and the ball valves (20) and (22) are opened at the same time. In this way, a part of the circulating waste gas can be passed into the anaerobic fermentation slurry, and then the escaping gas can be pressurized from the riser (18) to the cooling pipe (19) and enter the cooling system. The riser is above the stripping tower (1) and is connected to the waste gas pipe (12) and the cooling pipe (19). The cooled waste gas re-enters the autoclave reactor (2).

[0018] 3. The ball valve (20) is opened, and the ball valves (22) and (21) are closed. At this time, all the circulating gas flows back into the cooling system, and the cooled waste gas re-enters the autoclave reactor (2).

[0019] By adjusting the opening and closing of the hot water pump (5) or the vacuum pump (4), the temperature and pressure in the stripping tower are maintained at 80°C and 40-50kPa. Under this condition, the initial CO2 and NH3 can be volatilized from the anaerobic fermentation slurry after 2 hours, enter the circulation stage and then enter the subsequent stripping tower. Inorganic salt calcium sulfate is added to the autoclave reactor (2), which will react with the reaction product and form lime and ammonium sulfate to block the outlet. Therefore, the undissolved inorganic salt and lime particles need to be broken up with a stirrer (7) and stirred until the inlet and outlet are not blocked by the precipitated lime. The stirrer (7) is inside the autoclave reactor (2).

[0020] In order to absorb NH3 as much as possible, the circulating fan (6) is started, and the gas in the system begins to circulate. After NH3 is absorbed as much as possible, the heat exchanger (8) is closed, and the ball valve (14) in the hot water circulation is closed at the same time, so that the water temperature in the water storage container (3) is naturally cooled, and then the ball valve (15) is opened to pass the cooled cold water from the water storage container (3) into the heat exchange pipe of the stripping tower (1), and then the treated effluent is cooled. In this way, the latent heat of the treated anaerobic fermentation slurry is released into the cold water of the heat exchanger.

[0021] After the slag material treated in the stripping tower (1) is cooled, it is emptied from the slag discharge port (16), and the emptied stripping tower (1) can be fed with the next batch of materials. After each batch process is completed, the shut-off valve (23) is opened to discharge the nitrogen fertilizer from the reaction container (2) through the nitrogen fertilizer discharge port (17). At this time, a complete nitrogen fertilizer production batch is completed, and the subsequent batch processing can be completed according to the above operation.

Claims

1. A device for producing nitrogen fertilizer by anaerobic fermentation of biogas slurry, characterized in that: It comprises a negative pressure heating stripping tower (1), a kettle reactor (2), a water storage container (3), a vacuum pump (4), a water pump (5), a circulating fan (6), a heat exchanger (8), an exhaust pipe (12), an exhaust loop (13), a first ball valve (14), a second ball valve (15), a nitrogen fertilizer outlet (17), an ascending pipe (18), a cooling pipe (19), a first loop pipeline ball valve (20), a second loop pipeline ball valve (21), a third loop pipeline ball valve (22), and a heat exchange pipe (24); the cooling pipe (19) is connected to a cooling system; The heat exchanger (8) is located in the water storage container (3); the heat exchange pipe (24) is located in the negative pressure heating stripping tower (1); The hot water outlet pipe (10) of the water storage container (3) is connected to one end of the heat exchange pipe (24) via a first ball valve (14), and the water storage container (3) is also provided with an outlet connected to the one end of the heat exchange pipe (24) via a second ball valve (15), and the other end of the heat exchange pipe (24) is connected to the hot water return pipe (11) of the water storage container (3) via a water pump (5); The negative pressure heating stripping tower (1) is provided with an anaerobic fermentation sludge feed port (9), a slag discharge port (16) at the bottom, and a gas outlet at the top; the gas outlet is connected to one end of a waste gas pipe (12) via a riser (18) and a cooling pipe (19) in sequence, and the other end of the waste gas pipe (12) extends into the absorbent of the autoclave reactor (2); the autoclave reactor (2) is filled with a calcium sulfate solution absorbent, the upper part of the autoclave reactor (2) is connected to a vacuum pump (4), and the upper part of the autoclave reactor (2) is also provided with a waste gas circulation outlet, and the waste gas circulation outlet is connected to one end of a waste gas loop (13). A circulating fan (6) is provided on the waste gas loop (13). The other end of the waste gas loop (13) is divided into three branches. One branch is connected to the inlet end of the cooling pipe (19) via a first loop pipeline ball valve (20) and enters the cooling pipe (19) together with the gas coming out of the riser (18) and then enters the kettle reactor (2). The second branch is connected to the gas space at the top of the negative pressure heating stripping tower (1) via a second loop pipeline ball valve (21). The third branch is connected to the liquid space at the bottom of the negative pressure heating stripping tower (1), i.e., the anaerobic fermentation slurry, via a third loop pipeline ball valve (22).

2. The device for producing nitrogen fertilizer by anaerobic fermentation of biogas slurry according to claim 1, characterized in that: The kettle reactor (2) is of a conical structure, and a nitrogen fertilizer outlet (17) is provided at the bottom. The nitrogen fertilizer outlet (17) is provided with a shut-off valve (23).

3. The device for producing nitrogen fertilizer by anaerobic fermentation of biogas slurry according to claim 1, characterized in that: The kettle reactor (2) is also provided with a calcium sulfate solution adding device.

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