Method and system device for purifying sintering flue gas and co-producing water, fertilizer and heat energy

Abstract

The invention discloses a method and system device for purifying sintering flue gas and co-producing water, fertilizer and heat energy. The system device comprises an incineration unit, a waste heat utilization unit, a gas valve, a gas flowmeter, a supergravity flue gas trapping device, a liquid flowmeter, a liquid valve, a liquid conveying pump, a storage tank and a product outlet valve. The invention further discloses a method for purifying sintering flue gas and co-producing water, fertilizer and heat energy. The method comprises the following steps that 1, straw is fed into an incinerator to be fully combusted; (2) waste heat recovery is conducted on high-temperature flue gas obtained through incineration; (3) feeding the recovered low-temperature flue gas and the absorption liquid into a flue gas trapping device at the same time, and trapping acid gas to obtain an acid absorption liquid; and 4) conveying the obtained acidic absorption liquid to the saline-alkali soil for farmland irrigation. According to the method, multiple acid gases in the straw sintering flue gas are captured at the same time through an integrated method, the obtained absorption liquid is used for farmland irrigation of the saline-alkali soil, and improvement of the saline-alkali soil and yield increase of crops can be achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of comprehensive utilization of straw, and in particular relates to a method and a system device for purifying sintering flue gas and co-producing water, fertilizer and heat energy. Background Art

[0002] my country is a large agricultural country with abundant straw resources. The amount of straw resources that can be collected each year reaches 737 million tons. At present, the comprehensive utilization of crop straw in my country includes five directions: straw fertilizer, feed, base material, energy and raw material utilization. Among them, the utilization rate of straw fertilizer reaches 57.6%, indicating that straw is effectively utilized by returning it to the field as an important way to realize the utilization of straw resources and an important means to improve the fertility of farmland soil. However, under natural conditions, the degradation of straw directly returned to the field is slow, and the straw that is not degraded in time accumulates in the tillage layer, leading to the breeding of pests and diseases, hindering the nutrient cycle and seriously affecting crop planting and growth.

[0003] Among the existing straw utilization methods, the cost of directly returning straw to the fields is high, and it is difficult to effectively control crop diseases and pests, which may affect grain production; the utilization of straw as feed has problems such as high requirements for storage conditions, cautious use with some livestock after nitridation, and high labor costs; the utilization of straw as base material requires a strict sterile environment during storage and inoculation of bacterial sticks, and has high requirements for the straw storage environment; the utilization of straw as raw material has requirements for the moisture content of straw, and there are hidden dangers in the recovery and treatment of pulping waste liquid during the pulping process.

[0004] The utilization of straw as fuel, such as straw power generation and straw bale burning for heating, is an important way to realize the resource utilization of agricultural waste. However, the flue gas generated by the fuel utilization method will cause air pollution. Therefore, efficient flue gas purification technology is crucial to promote the resource utilization of straw and build a sustainable energy system. Through the implementation of flue gas purification technology, the dual goals of efficient utilization of straw resources and environmental protection can be achieved. At present, the annual average CO2 emission from open-air burning of straw in my country exceeds 5 million tons, but the sintering flue gas treatment technology is mainly concentrated in desulfurization, dust removal and denitrification. Most technologies are still at the stage of single pollutant control, and have failed to achieve coordinated control of pollutants and effective utilization of resources. In recent years, with the increasingly stringent requirements of the country for environmental protection, it is urgent to develop an advanced technology that can not only efficiently purify sintering flue gas, but also realize resource recycling. Summary of the invention

[0005] The first technical problem to be solved by the present invention is to provide a system device for purifying sintering flue gas and co-producing water, fertilizer and heat energy;

[0006] The second technical problem to be solved by the present invention is to provide a method for purifying sintering flue gas and co-producing water, fertilizer and heat energy. The method of the present invention solves the problems of low utilization rate of existing straw comprehensive utilization, long fertilizer use cycle of direct return to the field, adverse effects on crops, and serious pollution of straw burning and returning to the field. The method of the present invention effectively improves the comprehensive utilization rate of straw, and while solving the air pollution caused by burning straw, the method shortens the fertilizer use cycle and realizes the recovery of waste heat during the burning process. The recovered heat energy can be used for greenhouse insulation, winter heating, etc.; the method can achieve the co-production of water, fertilizer and heat energy, and the obtained flue gas absorption liquid is acidic and has the potential to improve saline-alkali land. The present invention opens up a new way to recycle waste straw and will bring new breakthroughs in the field of comprehensive utilization of straw. The present invention recovers the heat generated by straw burning and converts it into usable energy, with the heat of straw combustion 1.6×10 7 kJ / t, the recoverable heat is about 6.4×10 6 kJ / t, significantly improving energy utilization efficiency. Compared with the traditional straw recycling method, the method of the present invention solves the problems of low recovery rate, high pollution, high cost and complex process in the traditional straw recycling process.

[0007] To solve the above-mentioned first technical problem, the technical solution adopted by the present invention is as follows:

[0008] A system device for purifying sintering flue gas and co-producing water, fertilizer and heat energy, comprising a gas valve, a gas flow meter, an ultra-gravity flue gas capture device, a liquid flow meter, a liquid valve, a liquid delivery pump, a storage tank and a product outlet valve;

[0009] The supergravity device comprises a liquid phase inlet, a gas phase inlet, a liquid phase outlet and a gas phase outlet;

[0010] The inlet of the gas valve is connected to the sintering fume source pipeline;

[0011] The gas valve, the gas flow meter and the gas phase inlet of the supergravity device are connected in sequence through pipelines;

[0012] The storage tank, the liquid delivery pump, the liquid valve, the liquid flow meter and the liquid phase inlet of the supergravity device are connected through a pipeline.

[0013] To solve the above second technical problem, the technical solution adopted by the present invention is as follows:

[0014] A method for purifying sintering flue gas and co-producing water, fertilizer and heat energy comprises the following steps:

[0015] 1) Send the straw into the incinerator for full combustion;

[0016] 2) Recover waste heat from the high-temperature flue gas obtained by incineration;

[0017] 3) The low-temperature flue gas and the absorption liquid obtained after recovery are simultaneously sent to a flue gas capture device to capture acidic gases to obtain an acidic absorption liquid;

[0018] 4) The obtained acidic absorption liquid is transported to saline-alkali land for farmland irrigation or irrigation of crops adapted to acidic environment.

[0019] Preferably, in step 1), the straw processing in the incinerator can adopt different processing methods according to the specific incinerator design to optimize the combustion process and improve thermal efficiency, including but not limited to paving, layered stacking, mechanized crushing and spiral feeding.

[0020] Preferably, in step 2), the heat recovered from the waste heat is 1.6×10 7 kJ / t, about 6.4×10 6 kJ / t. The recovered heat energy can be used to heat the greenhouse, generate electricity and heat in winter.

[0021] Preferably, in step 3), the absorption liquid includes irrigation water or industrial wastewater containing ammonia; in addition to being used to capture acidic gases, the irrigation water or industrial wastewater containing ammonia can also be effectively utilized.

[0022] Preferably, in step 3), the flue gas capture device includes but is not limited to absorption equipment such as supergravity equipment, packed tower, plate tower, etc., preferably supergravity equipment; the rotation speed of the supergravity equipment is 500-2000rpm, preferably 1000-1500rpm.

[0023] Preferably, in step 3), before capturing the acid gas, there is no need to perform conventional particle dust removal on the flue gas.

[0024] Preferably, in step 3), the gas-liquid ratio of the low-temperature flue gas and the absorption liquid is 300-600; preferably 500-600.

[0025] Preferably, in step 3), the pH of the acidic absorption liquid is 5-6, which can be maintained for 5 days in an open state and 7 days in a closed state.

[0026] Preferably, in step 4), the acidic absorption liquid can be used for irrigation of saline-alkali farmland or irrigation of crops adapted to acidic environment. Crops adapted to acidic soil environment include but are not limited to watermelon, cauliflower, tea tree, blueberry, etc.

[0027] Any range described in the present invention includes the end value and any numerical value between the end values ​​and any sub-range formed by the end value or any numerical value between the end values.

[0028] Unless otherwise specified, all raw materials in the present invention can be purchased from the market, and the equipment used in the present invention can adopt conventional equipment in the relevant field or refer to the existing technology in the relevant field.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The present invention provides a method for purifying sintering flue gas and producing water, fertilizer and heat energy. The present invention reuses the combustion waste gas, realizes the capture of various acid gases such as carbon dioxide, sulfur dioxide, nitrogen oxides, etc. in the straw burning flue gas, and effectively improves the utilization rate of waste straw; with the heat of straw combustion 1.6×10 7 kJ / t, the recoverable heat is about 6.4×10 6 kJ / t, this recovery can be achieved only through the spiral tube heat exchanger structure in the existing waste heat boiler, which significantly improves the energy utilization efficiency;

[0031] 2. The present invention can also use low-concentration ammonia-containing wastewater as an absorbent to achieve the re-purification and utilization of industrial wastewater;

[0032] 3. The water fertilizer produced by the present invention has good stability and is easy to store. After being sealed and placed for one week, the pH value can still be maintained at ≤ 6. The raw materials described in the patent are easy to obtain and the cost is controllable, which meets the development requirements of resource conservation and environmental friendliness;

[0033] 4. The heat energy recovered by the present invention can be used for greenhouse insulation, winter heating, etc.;

[0034] 5. The water fertilizer produced by the present invention can be used for irrigation of saline-alkali farmland or crops adapted to acidic environment. Crops adapted to acidic soil environment include but are not limited to watermelon, cauliflower, tea tree, blueberry, etc.;

[0035] 6. The present invention provides a new method for treating waste straw, which solves the problem of greenhouse gas emissions caused by traditional straw burning and returning to the field, and provides a new idea for coping with global warming. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0037] Figure 1 The process flow chart of the method for purifying sintering flue gas and co-producing water, fertilizer and heat energy of the present invention;

[0038] Figure 2 This is a schematic diagram of the structure of the system device for purifying sintering flue gas and producing water, fertilizer and thermal energy according to the present invention. DETAILED DESCRIPTION

[0039] In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments. It should be understood by those skilled in the art that the following specific description is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

[0040] As one aspect of the present invention, a system device for purifying sintering flue gas and co-producing water, fertilizer and thermal energy includes 1-gas valve, 2-Venturi tube gas flowmeter, 3-Venturi tube liquid flowmeter, 4-liquid valve, 5-liquid delivery pump, 6-supergravity device, 7-product outlet valve, incineration unit, storage tank, etc.

[0041] As another aspect of the present invention, a method for purifying sintering flue gas to co-produce water, fertilizer and heat energy comprises the following steps:

[0042] 1) Send the straw into the incinerator for full combustion;

[0043] 2) Recover waste heat from the high-temperature flue gas obtained by incineration;

[0044] 3) The low-temperature flue gas and the absorption liquid obtained after recovery are simultaneously sent to a flue gas capture device to capture acidic gases to obtain an acidic absorption liquid;

[0045] 4) The obtained acidic absorption liquid is transported to saline-alkali land for farmland irrigation or irrigation of crops adapted to acidic environment.

[0046] According to certain embodiments of the present invention, in step 1), the straw processing in the incinerator can adopt different processing methods according to the specific incinerator design to optimize the combustion process and improve thermal efficiency, including but not limited to the use of flat paving, layered stacking, mechanized crushing and spiral feeding.

[0047] According to some embodiments of the present invention, in step 2), the heat of straw combustion is 1.6×10 7 kJ / t, the recoverable heat is about 6.4×10 6 kJ / t, this recovery can be achieved through the spiral tube heat exchanger structure in the existing waste heat boiler; the heat energy recovered from the waste heat can be used for greenhouse heating, and can also be used for power generation and winter heating.

[0048] According to certain embodiments of the present invention, in step 3), the absorption liquid includes irrigation water or industrial wastewater containing ammonia; in addition to being used to capture acidic gases, the irrigation water or industrial wastewater containing ammonia can also be effectively utilized.

[0049] According to certain embodiments of the present invention, in step 3), the flue gas capture device includes but is not limited to absorption equipment such as supergravity equipment, packed tower, plate tower, etc., preferably supergravity equipment; the rotation speed of the supergravity equipment is 500-2000rpm, preferably 1000-1500rpm.

[0050] According to some embodiments of the present invention, in step 3), there is no need to perform conventional particle dust removal on the flue gas before capturing the acid gas.

[0051] According to some embodiments of the present invention, in step 3), the gas-liquid ratio of the low-temperature flue gas and the absorption liquid is 300-600; preferably 500-600.

[0052] According to certain embodiments of the present invention, in step 3), the pH of the acidic absorption liquid is 5-6, which can be maintained for 5 days in an open state and 7 days in a closed state.

[0053] According to certain embodiments of the present invention, in step 4), the acidic absorption liquid can be used for irrigation of saline-alkali farmland or irrigation of crops adapted to acidic environment. Crops adapted to acidic soil environment include but are not limited to watermelon, cauliflower, tea tree, blueberry, etc.

[0054] The supergravity device used in the present invention is a prior art, such as the supergravity device disclosed in CN116196843A; such as the supergravity device disclosed in CN108771959B; such as the supergravity device disclosed in CN109647315A.

[0055] Example 1

[0056] A method for purifying sintering flue gas and co-producing water, fertilizer and heat energy comprises the following steps:

[0057] Corn stalks are selected and burned in an incinerator to obtain mixed flue gas, and the waste heat is recovered by a waste heat boiler to obtain cooled flue gas.

[0058] First, fill the high gravity device (RPB) with irrigation water, then pass the flue gas into the RPB, adjust the liquid delivery pump to make the gas-liquid ratio 500, and perform absorption at a high gravity speed of 1200rpm. Use a pH meter to detect the pH of the absorption liquid in the storage tank = 5.04;

[0059] The pH of the absorption liquid was measured every 24 hours. After being sealed and left to stand for one week, the pH could still be maintained at 5.63.

[0060] The outlet solution can be directly used as CO2 water fertilizer for irrigation, thereby improving the soil and promoting crop yields.

[0061] Example 2

[0062] A method for purifying sintering flue gas and co-producing water, fertilizer and heat energy comprises the following steps:

[0063] Corn stalks are selected and burned in an incinerator to obtain mixed flue gas, and the waste heat is recovered by a waste heat boiler to obtain cooled flue gas.

[0064] The ammonia-containing wastewater was diluted to pH=7.50, and the rotating packed bed was filled with the diluted ammonia-containing wastewater. The flue gas was then introduced into the RPB. The liquid delivery pump was adjusted to make the gas-liquid ratio 500, and the absorption was carried out at an ultra-gravity speed of 1200rpm. The pH of the absorption liquid in the storage tank was tested with a pH meter to be 5.51.

[0065] The pH of the absorption liquid was measured every 24 hours. After being sealed and left to stand for one week, the pH could still be maintained at 6.05.

[0066] The outlet solution can be directly used as CO2 water fertilizer for irrigation, thereby improving the soil and promoting crop yields.

[0067] Example 3

[0068] A method for purifying sintering flue gas and co-producing water, fertilizer and heat energy comprises the following steps:

[0069] Corn stalks are selected and burned in an incinerator to obtain mixed flue gas, and the waste heat is recovered by a waste heat boiler to obtain cooled flue gas.

[0070] The flue gas was introduced into the bottom of the absorption tower at a flow rate of 32L / min. The filler was Raschig ring filler. At a pressure of 1.8MPa (absolute pressure) at the top of the tower, the flue gas was absorbed in reverse flow with irrigation water at a volume flow rate of 20L / min. The pH meter detected the pH of the absorption liquid in the storage tank to be 5.62.

[0071] The pH of the absorption liquid was measured every 24 hours. After being sealed and left to stand for one week, the pH could still be maintained at 6.40.

[0072] The outlet solution can be directly used as CO2 water fertilizer for irrigation, thereby improving the soil and promoting crop yields.

[0073] The pH of the outlet solution in the above embodiments can be stable for more than one week; the irrigation water / ammonia-containing wastewater captures flue gas before irrigation, and the reducing sugar content of watermelon is increased by 15%, and the yield increase effect of cauliflower is close to 100 kg of organic fertilizer.

[0074] Comparative Example 1

[0075] Example 1 was repeated, except that the supergravity rotation speed was 300 rpm, which is outside the process parameter range claimed by the present invention.

[0076] Use a pH meter to test the pH of the absorption liquid in the storage tank = 5.37;

[0077] The pH of the absorption liquid was measured every 24 hours. After being sealed and left to stand for one week, the pH was 6.53.

[0078] It can be seen that according to the pH value obtained in this comparative example, when the supergravity rotation speed is 300rpm, pH>6.0, so that the produced water fertilizer cannot maintain pH≤6 after being sealed and left to stand for one week.

[0079] Comparative Example 2

[0080] Example 1 was repeated, with the only difference being that the gas-liquid ratio was 250, which is outside the process parameter range claimed by the present invention.

[0081] Use a pH meter to test the absorption liquid in the storage tank. pH = 5.44;

[0082] The pH of the absorption liquid was measured every 24 hours. After being sealed and left to stand for one week, the pH could still be maintained at 6.01.

[0083] It can be seen that according to the pH value obtained in this comparative example, when the gas-liquid ratio is 250, pH>6.0, so that the produced water fertilizer cannot maintain pH≤6 after being sealed and left to stand for one week.

[0084] Obviously, the above embodiments of the present invention are merely examples for clearly explaining the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to list all implementation methods here. Any obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A system device for purifying sintering flue gas and producing water, fertilizer and heat energy, characterized by: Including gas valves, gas flow meters, supergravity fume capture devices, liquid flow meters, liquid valves, liquid delivery pumps, storage tanks and product outlet valves; The supergravity device comprises a liquid phase inlet, a gas phase inlet, a liquid phase outlet and a gas phase outlet; The inlet of the gas valve is connected to the sintering fume source pipeline; The gas valve, the gas flow meter and the gas phase inlet of the supergravity device are connected in sequence through pipelines; The storage tank, the liquid delivery pump, the liquid valve, the liquid flow meter and the liquid phase inlet of the supergravity device are connected through a pipeline.

2. A method for purifying sintering flue gas and co-producing water, fertilizer and heat energy using the device of claim 1, characterized in that: The steps include: 1) Send the straw into the incinerator for full combustion; 2) Recover waste heat from the high-temperature flue gas obtained by incineration; 3) The low-temperature flue gas and the absorption liquid obtained after recovery are simultaneously sent to a flue gas capture device to capture acidic gases to obtain an acidic absorption liquid; 4) The obtained acidic absorption liquid is transported to saline-alkali land for farmland irrigation or irrigation of crops adapted to acidic environment.

3. The method for purifying sintering flue gas and co-producing water, fertilizer and heat energy according to claim 2, characterized in that: In step 1), the method for processing the straw in the incinerator includes one of flat paving, layered stacking, mechanized crushing and spiral feeding.

4. The method for purifying sintering flue gas and co-producing water, fertilizer and heat energy according to claim 2, characterized in that: In step 2), the waste heat recovery refers to recovering the waste heat in the waste heat boiler by using water as a medium, and generating cooling flue gas at the same time.

5. The method for purifying sintering flue gas and co-producing water, fertilizer and heat energy according to claim 2, characterized in that: In step 2), the temperature of the high-temperature flue gas is in the range of 700-900°C, and the temperature of the flue gas after waste heat recovery is in the range of 50-70°C.

6. The method for purifying sintering flue gas and co-producing water, fertilizer and heat energy according to claim 2, characterized in that: In step 3), the absorption liquid includes irrigation water or industrial ammonia-containing wastewater.

7. The method for purifying sintering flue gas and co-producing water, fertilizer and heat energy according to claim 2, characterized in that: In step 3), the fume capture device includes but is not limited to absorption equipment such as supergravity equipment, packed tower, plate tower, etc., preferably supergravity equipment; the rotation speed of the supergravity equipment is 500-2000rpm, preferably 1000-1500rpm.

8. The method for purifying sintering flue gas and co-producing water, fertilizer and heat energy according to claim 2, characterized in that: In step 3), the gas-liquid ratio of the low-temperature flue gas and the absorption liquid is 300-600, preferably, the gas-liquid ratio is 500-600.

9. The method for purifying sintering flue gas and co-producing water, fertilizer and heat energy according to claim 2, characterized in that: In step 3), the pH of the acidic absorption liquid is 5-6, which can be maintained for 5 days in an open state and 7 days in a closed state.

10. The method for purifying sintering flue gas and co-producing water, fertilizer and heat energy according to claim 2, characterized in that: In step 4), the acidic absorption liquid can be used for irrigation of saline-alkali farmland or irrigation of crops adapted to acidic environment. Crops adapted to acidic soil environment include but are not limited to watermelon, cauliflower, tea tree, blueberry, etc.

Images