Cremation Exhaust Gas Purification System and Purification Method

Abstract

The present invention provides a cremation tail gas purification system and a purification method. The cremation tail gas purification system includes: a blower, a combustion device, a quenching device, an acid gas removal unit, and a catalytic denitration unit. The blower is provided with a cremation tail gas inlet and a cremation tail gas outlet; the first feed port of the combustion device is communicated with the cremation tail gas outlet, and the second feed port is used for conveying fuel and combustion-supporting gas; the combustion tail gas inlet of the quenching device is connected to the combustion tail gas outlet; the cooling gas inlet of the acid gas removal unit is communicated with the cooling gas outlet; the primary purification gas inlet and the primary purification gas outlet of the catalytic denitration unit are communicated through a primary purification gas pipeline. By adopting the above purification system, the removal rates of acid gases and nitrogen oxides in the cremation tail gas can be greatly improved, the content of dioxins can be reduced, and the dust content in the purified tail gas is relatively low.

Description

Technical Field

[0001] The present invention relates to the field of tail gas purification, and more particularly, to a cremation tail gas purification system and a purification method. Background Art

[0002] The incineration tail gas generated during the existing cremation process includes acidic gases, nitrogen oxides, dust, dioxins, and unburned harmful components, etc. The above components pose problems of environmental pollution. In order to improve the environmental protection of cremators, the art has mainly configured purification equipment for some pollutants in a targeted manner. However, with the tightening of emission standards, the flue gas emissions of existing cremators face the risk of non-compliance, which requires a comprehensive and reasonable configuration of the flue gas purification system to achieve deep purification of the tail gas and compliant emissions.

[0003] The first piece of prior art (CN 103157338 B) provides a full dry post-treatment system for cremator flue gas, that is, a post-treatment device including a smoke-water isolation type quenching device, a powder spraying device, a dust collector, and an adsorption device is used to treat the flue gas generated by the cremator. The device has a simple setting, but does not treat harmful substances such as acidic gases, nitrogen oxides, and dioxins, which is likely to cause environmental pollution.

[0004] The second piece of prior art (CN 102120132 B) provides a cremation flue gas purification treatment device. The core system of the device is integrated by a flue gas mixing chamber, a heat and cold exchanger, an acid removal system, a wet and dry separator, and a bag filter, and can effectively remove acidic inorganic pollutants and dioxin-like organic pollutants in the cremation flue gas at the same time. However, considering the existing flue gas emission requirements, the device has caused the over-standard emissions of nitrogen oxides and combustible gases.

[0005] The third piece of prior art (CN109084304A) provides a flue gas purification device, which is characterized by an integrated system made by connecting a secondary combustion chamber, a quenching tower, a sedimentation chamber, a bag filter, an activated carbon tank, and an acid removal tower in series through pipelines. The system can achieve acid removal, dust reduction, and removal of harmful gases such as dioxins, but the removal rate of nitrogen oxides is relatively low, resulting in a large amount of nitrogen oxides in the tail gas, so there is a problem of over-standard emissions of nitrogen oxides in the tail gas.

[0006] The fourth piece of prior art (CN209355252U) provides a tail gas treatment system directly connected to a cremator, which consists of an emergency emission chimney, a vertical air cooler, a cyclone dust collector, a bag filter, an activated carbon adsorber, a draft fan, and a smoke exhaust pipe. However, its purification degree of harmful gases is not high, resulting in the presence of harmful gases in the tail gas, and it will face the problem of over-standard emissions of harmful gases.

[0007] It can be seen from this that the existing cremator tail gas purification system has a poor purification effect, resulting in the problem that the harmful gas emissions in the purified tail gas exceed the standard. Therefore, it is necessary to provide a purification system with a high purification effect for cremation tail gas. Summary of the Invention

[0008] The main object of the present invention is to provide a cremation tail gas purification system and a purification method to solve the problem that the existing cremator tail gas purification system has a poor purification effect, resulting in the problem that the emissions of the purified tail gas exceed the standard.

[0009] To achieve the above object, on the one hand, the present invention provides a purification system for cremation tail gas, which includes: a fan, a combustion device, a quenching device, an acid gas removal unit, and a catalytic denitration unit. The fan is provided with a cremation tail gas inlet and a cremation tail gas outlet; the combustion device is provided with a first feed port, a second feed port, and a combustion tail gas outlet, wherein the first feed port is communicated with the cremation tail gas outlet, and the second feed port is used for conveying fuel and combustion-supporting gas; the quenching device is provided with a refrigerant inlet, a combustion tail gas inlet, and a cooling gas outlet, and the combustion tail gas inlet is connected to the combustion tail gas outlet; the acid gas removal unit is provided with a cooling gas inlet, an alkaline acid removal agent inlet, and a primary purified gas outlet, and the cooling gas inlet is communicated with the cooling gas outlet for removing acid gas in the cooling gas; and the catalytic denitration unit is provided with a catalyst inlet, a reducing agent inlet, a primary purified gas inlet, and a purified tail gas outlet, and the primary purified gas inlet is communicated with the primary purified gas outlet through a primary purified gas pipeline.

[0010] Further, the combustion device includes: a primary heat exchange device, a combustion chamber, and a secondary heat exchange device. The primary heat exchange device is used for exchanging heat between the combustion tail gas and the cremation tail gas; the combustion chamber is used for burning the cremation tail gas treated by the primary heat exchange device to obtain combustion tail gas; and the secondary heat exchange device is used for exchanging heat between the combustion tail gas and the combustion-supporting gas.

[0011] Further, the acid gas removal unit includes: an alkaline acid removal agent supply device provided with an alkaline acid removal agent supply port; and an acid gas removal device provided with a cooling gas inlet, an alkaline acid removal agent inlet, and a primary purified gas outlet, and the alkaline acid removal agent inlet is communicated with the alkaline acid removal agent supply port.

[0012] Further, the purification system includes an adsorption and dust removal device arranged on the flow path between the quenching device and the acid gas removal unit for removing dioxins and heavy metal elements in the cooling gas.

[0013] Further, the adsorption and dust removal device includes an adsorption device and a dust removal device. The adsorption device is provided with a cooling gas inlet and a dust-containing tail gas outlet; the dust removal device is provided with a dust-containing tail gas inlet and a primary purified gas outlet. The cooling gas inlet is communicated with the cooling gas outlet, and the dust-containing tail gas outlet is communicated with the dust-containing tail gas inlet.

[0014] Further, the catalytic denitration unit includes: a catalyst supply device, a reducing agent supply device, and a catalytic denitration device. The catalyst supply device is provided with a catalyst supply port; the reducing agent supply device is provided with a reducing agent supply port; the catalytic denitration device is provided with a catalyst inlet, a reducing agent inlet, a primary purified gas inlet, and a purified gas outlet. The catalyst inlet is communicated with the catalyst supply port, and the reducing agent inlet is communicated with the reducing agent supply port.

[0015] Further, the purification system further includes a boosting device, and the boosting device is arranged on the primary purified gas pipeline.

[0016] Further, the purification system further includes a flue gas heat exchange device, and the flue gas heat exchange device is used to heat up the primary purified tail gas discharged from the boosting device.

[0017] Further, the purification system further includes an alkali washing device, and the alkali washing device is used to perform alkali washing on the tail gas discharged from the purified gas outlet.

[0018] On the other hand, the present application also provides a method for purifying cremation tail gas. The purification method includes: accelerating the cremation tail gas by a fan and burning it with fuel and combustion-supporting gas to obtain combustion tail gas; quenching the combustion tail gas to obtain cooling gas; removing acidic gas in the cooling gas to obtain primary purified gas; and performing catalytic denitration reaction on the primary purified gas and a reducing agent under the action of a catalyst to obtain purified tail gas.

[0019] Further, the step of removing acidic gas in the cooling gas includes: reacting an alkaline acid remover with the acidic gas in the cooling gas to remove the acidic gas in the cooling gas; preferably, the alkaline acid remover is selected from one or more of the group consisting of sodium bicarbonate, calcium hydroxide, or quicklime.

[0020] Further, the temperature of the combustion process is 850 - 900 °C, and the time is 2 - 3 s.

[0021] Further, the combustion process further includes heat exchange of the combustion tail gas with the combustion-supporting gas and the cremation tail gas conveyed by the fan in sequence. Preferably, the temperature of the combustion tail gas is reduced to 550 °C.

[0022] Further, the quenching step includes quenching the combustion tail gas with a mixture of water and compressed air as a refrigerant. Preferably, after the quenching step, the temperature of the combustion tail gas is 200 - 230 °C.

[0023] Further, before the step of removing acidic gases from the cooling gas, the purification method further includes: adsorbing the cooling gas with an adsorbent and then performing dust removal treatment; preferably, the adsorbent is activated carbon.

[0024] Further, between the step of removing acidic gases from the cooling gas and the catalytic denitrification reaction step, the purification method further includes: pressurizing the primary purified gas.

[0025] Further, the catalyst is selected from one or more of the group consisting of V2O5, WO3, and TiO2; the reducing agent is selected from one or more of the group consisting of ammonia water, urea, and liquid ammonia.

[0026] Further, the purification method further includes: cooling the primary purified gas after pressurization treatment, and simultaneously heating the purified tail gas; preferably, the temperature of the purified tail gas and the primary purified gas is 50 - 140 °C.

[0027] Applying the technical solution of the present invention, the fan can create a negative pressure at the cremation tail gas inlet, which is beneficial to improving the transportation efficiency of the cremation tail gas, and at the same time is also beneficial to suppressing the escape of harmful gases and improving the environmental protection of the purification system; in the combustion system, the cremation tail gas undergoes secondary combustion, which is beneficial to improving the combustion degree of organic substances in the cremation tail gas and reducing the content of harmful gases such as CO; in the quenching device, the combustion tail gas is quenched, which can inhibit the secondary synthesis of dioxins in the subsequent process; the quenched cooling gas is transported to the adsorption and dust removal device, which can first adsorb dioxins and heavy metal elements in the cooling gas and then remove them from the cooling gas to obtain the primary purified gas; the primary purified gas passes through the denitrification device to remove nitrogen-containing compounds therein to obtain the secondary purified gas; in the washing device, the acidic gases in the secondary purified gas are removed by washing, thereby purifying the tail gas. In summary, using the above purification system can greatly improve the removal rates of acidic gases and nitrogen oxides in the cremation tail gas, reduce the content of dioxins, and the dust content in the purified tail gas is relatively low. Description of the Drawings

[0028] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0029] Figure 1 shows a schematic structural diagram of a cremator tail gas purification system provided according to a preferred embodiment of the present invention; and

[0030] Figure 2 shows a schematic structural diagram of a combustion device provided according to a preferred embodiment of the present invention.

[0031] The above drawings include the following reference numerals:

[0032] 10. Fan; 20. Combustion device; 21. Primary heat exchange device; 211. Heat absorption side; 212. Heat release side; 22. Combustion chamber; 23. Secondary heat exchange device; 201. First feed inlet; 202. Second feed inlet; 203. Combustion chamber outlet; 204. Combustion exhaust gas outlet; 30. Quenching device; 40. Adsorption and dust removal device; 41. Adsorption device; 42. Dust removal device; 50. Acid gas removal unit; 51. Alkaline deacidifier supply device; 52. Acid gas removal device; 60. Catalytic denitration unit; 61. Catalyst supply device; 62. Reductant supply device; 63. Catalytic denitration device; 70. Pressurization device; 80. Flue gas heat exchange device. DETAILED DESCRIPTION

[0033] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0034] As described in the background technology, the existing cremator tail gas purification system has the problem of being unable to remove all pollutants at the same time. In order to solve the above technical problems, the present application provides a cremator tail gas purification system, such as Figure 1 As shown, the purification system includes: a fan 10, a combustion device 20, a quenching device 30, an acid gas removal unit 50 and a catalytic denitration unit 60. The fan 10 is provided with a cremation tail gas inlet and a cremation tail gas outlet; the combustion device 20 is provided with a first feed port 201 and a second feed port 202 and a combustion tail gas outlet 204, wherein the first feed port 201 is connected to the cremation tail gas outlet, and the second feed port 202 is used to transport fuel gas and combustion-supporting gas; the quenching device 30 is provided with a combustion tail gas inlet and a cooling gas outlet, and the combustion tail gas inlet is connected to the combustion tail gas outlet 204; the acid gas removal unit 50 is provided with a cooling gas inlet, an alkaline deacidifying agent inlet and a primary purified gas outlet, and the cooling gas inlet is connected to the cooling gas outlet for removing acid gas in the cooling gas; the catalytic denitration unit 60 is provided with a catalyst inlet, a reducing agent inlet, a primary purified gas inlet and a purified gas outlet, and the primary purified gas inlet is connected to the primary purified gas outlet through a primary purified gas delivery pipeline.

[0035] In the above purification system provided by the present application, the fan 10 can create a negative pressure at the cremation exhaust gas inlet, which is beneficial to improving the transportation efficiency of the cremation exhaust gas. At the same time, it is also beneficial to inhibit the escape of harmful gases and improve the environmental protection performance of the purification system. In the combustion system, the cremation exhaust gas undergoes secondary combustion, which is beneficial to improving the combustion degree of organic matter in the cremation exhaust gas and reducing the content of harmful gases such as CO. In the quenching device 30, the combustion exhaust gas is quenched to inhibit the secondary synthesis of dioxins in the subsequent process. The quenched cooling gas is transported to the acid gas removal unit 50, where it reacts with the alkaline acid remover to remove the acid gas in the cooling gas and obtain the primary purified gas. The primary purified gas is input into the catalytic denitrification unit 60, where it reacts with the reducing agent under the action of the catalyst to remove the nitrogen-containing compounds and obtain the purified exhaust gas. In summary, using the above purification system can greatly improve the removal rate of acid gases and nitrogen oxides in the cremation exhaust gas, reduce the content of dioxins, and the soot content in the purified exhaust gas is relatively low.

[0036] Preferably, the above purification system may include multiple cremators and multiple fans 10 connected to them one by one to ensure the stable and reliable operation of the cremators during each working period and ensure the stability of the negative pressure in each cremator system. Preferably, the above fan 10 is a high-temperature fan. The high-temperature fan has good high-temperature resistance, so it can ensure the operation stability of the entire system.

[0037] In a preferred embodiment, the combustion device 20 includes: a primary heat exchange device 21, a combustion chamber 22, and a secondary heat exchange device 23. The primary heat exchange device 21 is used to exchange heat between the combustion exhaust gas and the cremation exhaust gas. The combustion chamber 22 is used to combust the cremation exhaust gas treated by the primary heat exchange device 21 to obtain the combustion exhaust gas. The secondary heat exchange device 23 is used to exchange heat between the above combustion exhaust gas and the combustion-supporting gas.

[0038] The above primary heat exchange device 21 and secondary heat exchange device 23 only need to be able to achieve heat exchange, and their structures are not specifically limited. Preferably, as Figure 2As shown, the primary heat exchange device 21 includes an endothermic side 211 and an exothermic side 212, which are separated by a partition with heat conduction function. The cremation tail gas enters the endothermic side of the primary heat exchange device 21 through the first feed port 201. At the same time, the combustion gas in the combustion chamber 22 is discharged through the combustion chamber outlet 203, and then transported to the exothermic side of the primary heat exchange device 21. The heat of the exothermic side 212 is conducted to the endothermic side to raise the temperature of the cremation tail gas, and the heated cremation tail gas enters the combustion chamber 22. The combustion tail gas after the first heat exchange is transported to the secondary heat exchange device 23. At the same time, the combustion-supporting gas enters the secondary heat exchange device 23 through the second feed port 202, and the two perform non-contact heat exchange. The heated combustion-supporting gas is transported to the combustion chamber 22, and at the same time, the combustion gas after the second heat exchange enters the subsequent quenching device 30. Using the above combustion device 20 can, on the one hand, burn the cremation tail gas, and on the other hand, make full use of the heat in the combustion process to reduce energy loss.

[0039] The combustion process is carried out at a relatively high temperature, which is conducive to reducing the generation of dioxins. Therefore, in order to reduce the content of dioxins and improve the utilization rate of heat at the same time, the combustion tail gas with a relatively high temperature is first subjected to the first heat exchange with the cremation tail gas that subsequently enters the combustion device 20 in the first heat exchange device. The combustion tail gas after the first heat exchange is then subjected to the second heat exchange with the combustion-supporting gas in the second heat exchange device. The cremation tail gas and the combustion-supporting gas after heat exchange enter the combustion chamber 22 for combustion to obtain the combustion tail gas. Through the combustion device 20, on the one hand, the combustible gas in the cremation tail gas can be removed by combustion, which is conducive to improving the purification degree of the finally obtained purified tail gas, and on the other hand, the heat recycling utilization rate can be improved through heat exchange.

[0040] The above acid gas removal unit 50 only needs to be able to achieve the effect of removing acid gas, and its specific structure is not limited. In a preferred embodiment, the above acid gas removal unit 50 includes an alkaline acid removal agent supply device 51 and an acid gas removal device 52. The alkaline acid removal agent supply device 51 is provided with an alkaline acid removal agent supply port, and the acid gas removal device 52 is provided with a cooling gas inlet, an alkaline acid removal agent inlet, and a primary purified gas outlet, and the alkaline acid removal agent inlet is communicated with the alkaline acid removal agent supply port. In the above acid gas removal unit 50, the alkaline acid removal agent provided by the alkaline acid removal agent supply device 51 and the acid gas in the cooling gas undergo an acid-base neutralization reaction in the acid gas removal device 52, so that the acid gas can be removed by a chemical reaction method. Using the acid gas removal unit 50 with the above structure to remove the acid gas in the cooling gas is beneficial to improving its removal efficiency, thereby further improving the purification degree of the purified tail gas discharged from the catalytic denitrification process.

[0041] Preferably, the above alkaline acid removal agent supply device 51 is a sodium bicarbonate supply device, a calcium hydroxide supply device, or a quicklime supply device.

[0042] In a preferred embodiment, the above purification system further includes an adsorption and dust removal device 40, which is arranged on the flow path between the quenching device 30 and the acid gas removal unit 50, and is used to remove dioxins and heavy metal elements in the cooling gas.

[0043] Preferably, the above adsorption and dust removal device 40 includes an adsorption device 41 and a dust removal device 42. The adsorption device 41 is provided with a cooling gas inlet, an adsorbent inlet, and a dust-containing tail gas outlet; the dust removal device 42 is provided with a dust-containing tail gas inlet and a primary purified gas outlet. The cooling gas inlet is communicated with the cooling gas outlet, and the dust-containing tail gas outlet is communicated with the dust-containing tail gas inlet.

[0044] In the adsorption device 41, dioxins and metal elements contained in the cooling gas discharged from the quenching device 30 can be removed through adsorption. However, since the adsorbent will cause a problem of high solid content in the dust-containing tail gas discharged from the adsorption device, the subsequent dust removal device 42 is used to treat it to remove solid particles in the dust-containing tail gas and obtain primary purified gas. Preferably, the above dust removal device 42 is a bag dust removal device 42. A low-pressure spray pulse bag filter is used to collect the soot in the flue gas. The dust-containing flue gas enters the box body from the air inlet of the dust removal chamber, and the purified gas enters the box body through the filter bag mouth in the filter bag and is discharged from the air outlet. To prevent the flue gas from condensing and affecting the normal operation of the bag filter, the filter has perfect overall heat preservation and heating measures.

[0045] In the above purification system, the catalytic denitrification unit 60 can adopt the types commonly used in the art. Preferably, the above catalytic denitrification unit 60 includes: a catalyst supply device 61, a reducing agent supply device 62, and a catalytic denitrification device 63. The catalyst supply device 61 is provided with a catalyst supply port, the reducing agent supply device 62 is provided with a reducing agent supply port, the catalytic denitrification device 63 is provided with a catalyst inlet, a reducing agent inlet, a primary purified gas inlet, and a purified tail gas outlet. The catalyst inlet is communicated with the catalyst supply port, and the reducing agent inlet is communicated with the reducing agent supply port. In the catalytic denitrification unit 60, nitrogen oxides in the primary purified gas can be reduced to form environmentally friendly gases such as nitrogen. More preferably, the above catalytic denitrification device 63 is an SCR denitrification device (selective catalytic denitrification device).

[0046] In a preferred embodiment, the purification system further includes a boosting device 70, which is arranged on the primary purified gas pipeline. The boosting device 70 can provide the power required for the operation of the above purification system. By arranging the boosting device 70 between the bag filter and the ozone oxidation denitration device, on the one hand, it can provide the negative pressure for the operation of the front-stage internal circulation regenerative combustion system, the flue gas quenching device 30 and the bag filter, and on the other hand, it can provide the operation power for the rear-stage ozone oxidation denitration device and the washing device. Furthermore, in order to reduce the influence of the pressure fluctuation of the fan 10 caused by the large variation range of the air volume of the fan 10, multiple boosting devices 70 are arranged in parallel in the flue gas purification system.

[0047] Preferably, the purification system further includes a flue gas heat exchange device 80. The flue gas heat exchange device 80 can use at least part of the purified tail gas discharged from the catalytic denitration device 63 to heat up the primary purified gas discharged from the boosting device 70. The heated primary purified gas enters the catalytic denitration device 63 for catalytic denitration reaction, which is beneficial to improving the catalytic denitration efficiency and shortening the process time.

[0048] In a preferred embodiment, the above purification system further includes an alkali washing device 90, which is used for alkali washing the tail gas discharged from the purified gas outlet. Through the alkali washing process, acidic gases in the tail gas can be further removed to achieve further purification.

[0049] On the other hand, the present application also provides a method for purifying cremation tail gas, which includes: accelerating the cremation tail gas by a fan and burning it with fuel and combustion-supporting gas to obtain combustion tail gas; quenching the combustion tail gas to obtain a cooling zone; removing acidic gases in the cooling gas to obtain primary purified gas; and carrying out a catalytic denitration reaction on the primary purified gas and a reducing agent under the action of a catalyst to obtain purified tail gas.

[0050] In the above purification method provided by this application, the setting of the fan enables the cremation tail gas to be input under negative pressure conditions. This not only helps improve the transportation efficiency of the cremation tail gas, making the entire purification system operate in a negative pressure environment, but also helps inhibit the escape of harmful gases and improve the environmental protection of the purification system. In the combustion system, the cremation tail gas undergoes secondary combustion, which helps improve the combustion degree of organic matter in the cremation tail gas and reduce the content of harmful gases such as CO. Quenching the combustion tail gas helps inhibit the secondary synthesis of dioxins in the subsequent process. Adsorbing and dust-removing the cooled gas after quenching can first adsorb dioxins and heavy metal elements in the cooled gas and then remove them from the cooled gas to obtain a primary purified gas. Passing the primary purified gas through a catalytic denitrification reaction can remove nitrogen-containing compounds therein to obtain a secondary purified gas. Removing acidic gases in the secondary purified gas through washing can further purify the tail gas. In summary, adopting the above purification method can greatly improve the removal rates of acidic gases and nitrogen oxides in the cremation tail gas, reduce the content of dioxins, and the dust content in the purified tail gas is relatively low.

[0051] In a preferred embodiment, the step of removing acidic gases from the cooled gas includes: reacting an alkaline acid remover with the acidic gases in the cooled gas to remove the acidic gases in the cooled gas. The acidic gases can react with the alkaline acid remover and then be absorbed, achieving the effect of removing them from the cooled gas. Preferably, the alkaline acid remover includes one or more of the group consisting of sodium bicarbonate, calcium hydroxide, or quicklime. Compared with other types of alkaline acid removers, the above several acid removers have lower costs and larger adsorption amounts of acidic gases.

[0052] In a preferred embodiment, the cremation tail gas is burned at 850 - 900 °C for 2 - 3 s. Conducting the combustion process at a relatively high temperature helps reduce the generation of dioxins. Therefore, in order to reduce the content of dioxins and improve the utilization rate of heat at the same time. More preferably, the combustion tail gas with a relatively high temperature is first heat-exchanged with the subsequent incoming cremation tail gas for the first time, and the combustion tail gas after the first heat exchange is heat-exchanged with the combustion-supporting gas for the second time again. After heat exchange, the cremation tail gas and the combustion-supporting gas are burned to obtain the combustion tail gas.

[0053] In a preferred embodiment, the combustion process further includes heat-exchanging the combustion tail gas with the combustion-supporting gas and the cremation tail gas conveyed by the fan in sequence. Conducting the combustion process at a relatively high temperature helps reduce the generation of dioxins. Therefore, in order to reduce the content of dioxins and improve the utilization rate of heat at the same time, the combustion tail gas with a relatively high temperature is first heat-exchanged with the subsequent incoming cremation tail gas in the first heat exchange device for the first time, and the combustion tail gas after the first heat exchange is heat-exchanged with the combustion-supporting gas in the second heat exchange device for the second time again. More preferably, the temperature of the combustion tail gas is reduced to 550 °C.

[0054] In a preferred embodiment, the above-mentioned quenching step includes quenching the combustion exhaust gas with a mixture of water and compressed air as the refrigerant. Using the mixture of water and compressed air as the refrigerant together is beneficial to increasing the contact area between the refrigerant and the combustion exhaust gas on the one hand, and to improving its cooling efficiency on the other hand. Preferably, after the quenching step, the temperature of the cooling gas is 200-230°C. Quenching the combustion exhaust gas to the above temperature range is beneficial to suppressing the secondary synthesis of dioxins.

[0055] In a preferred embodiment, before the step of removing acidic gases from the cooling gas, the above purification method further includes: adsorbing the cooling gas with an adsorbent and then performing dust removal treatment. The contact between the adsorbent and the cooling gas discharged from the quenching step can adsorb the dioxins and metal elements contained therein. However, since the adsorbent will cause a problem of high solid content in the dust-containing tail gas discharged from the adsorption device, a dust removal device 42 is subsequently used to treat it to remove solid particles in the dust-containing tail gas and obtain a primary purified gas. Preferably, the above-mentioned dust removal device 42 is a bag dust removal device. More preferably, a low-pressure spray pulse bag filter is used to collect the soot in the flue gas. The dust-containing flue gas enters the box body through the air inlet of the dust removal chamber, and the purified gas enters the box body through the filter bag mouth in the filter bag and is discharged through the air outlet. To prevent the flue gas from condensing and affecting the normal operation of the bag filter, the dust filter is provided with perfect overall heat preservation and heating measures. Preferably, the above-mentioned adsorbent includes but is not limited to activated carbon.

[0056] In a preferred embodiment, between the step of removing acidic gases from the cooling gas and the catalytic denitrification reaction step, the above purification method further includes: pressurizing the primary purified gas. Setting the pressurization step can, on the one hand, enable the previous combustion step, quenching step and dust collection step to be carried out under negative pressure, and on the other hand, provide operating power for the subsequent denitrification step and washing step, thereby reducing the influence of the fan air pressure fluctuation caused by the large change range of the fan air volume and improving the purification rate.

[0057] In a preferred embodiment, during the catalytic denitrification process, the catalyst includes but is not limited to one or more of the group consisting of V2O5, WO3 and TiO2; the reducing agent includes but is not limited to one or more of the group consisting of ammonia water, urea and liquid ammonia. Among them, for every 100,000 Nm 3 cremation exhaust gas, the dosage of the catalyst is 15-25 m 3 , and the dosage of the reducing agent is 480-600 kg.

[0058] In a preferred embodiment, the purification method further includes: cooling the primary purified gas after pressurization treatment, and simultaneously heating the purified tail gas; preferably, the temperature increase range of the purified tail gas is 50 - 140°C, and the temperature decrease range of the primary purified gas is 120 - 200°C. Cooling the primary purified gas discharged after pressurization treatment is beneficial for the primary purified gas to meet the performance requirements of flue gas denitrification at an appropriate denitrification reaction temperature. And heating the tail gas discharged during the washing process to make its discharge temperature reach above the dew point can achieve deep white elimination and reduce the corrosion of the purified tail gas to the flue and chimney.

[0059] To further purify the tail gas, preferably, the above purification method further includes: further absorbing the acidic gas in the tail gas discharged from the catalytic denitrification step by using an alkaline solution (such as sodium hydroxide solution, calcium hydroxide solution), and simultaneously removing the liquid water carried in the tail gas by using a demisting device. More preferably, the demisting effect reaches that the moisture content of the outlet flue gas is not more than 50mg / Nm 3 , and introducing the demisted flue gas into the GGH to achieve flue gas reheating for white elimination and comprehensive utilization of the internal heat energy of the system.

[0060] The following further describes the present application in detail with specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present application.

[0061] Embodiment 1

[0062] The cremation tail gas (450°C) discharged from the underground flue outlets of multiple cremators is sent into the aggregation flue by the corresponding pre - installed high - temperature fans 10 respectively, and then is transported to the combustion device 20 (internal - circulation regenerative combustion system) for secondary combustion, and the temperature of the cremation tail gas is raised to 900°C and stays for 5 seconds to obtain the combustion tail gas, and the above - mentioned combustion tail gas is respectively heat - exchanged with the subsequent combustion - supporting gas and cremation tail gas to realize partial heat energy recycling.

[0063] The heat - exchanged combustion tail gas is transported to the quenching device 30 for cooling, and the quenched combustion tail gas is cooled from 600°C to 250°C to obtain the cooled gas.

[0064] The cooled gas enters the acidic gas removal unit 50, and in the acidic gas removal device 52 (dry - type deacidification reactor), it is in full contact with the sprayed alkaline deacidifying agent NaHCO3 (600 - mesh) dry powder and the adsorbent activated carbon, and then the dust - containing tail gas after desulfurization enters the dust removal device 42 (bag filter) for further dust removal to obtain the primary purified gas. The temperature of the primary purified gas is 235°C.

[0065] Then the above - mentioned 235°C primary purified tail gas is transported to the catalytic denitrification device 63 (the SCR catalyst is V2O5, per one hundred thousand Nm 3 cremation tail gas, and the dosage of the catalyst is 20m 3In [the reactor] for catalytic denitrification reaction, the secondary purified tail gas is obtained, where the sulfur dioxide content in the secondary purified tail gas is less than 50 mg / Nm 3 .

[0066] (4) Use NaOH alkaline solution to further deeply absorb the acidic gases in the flue gas in the wet scrubbing tower. There is a demisting device at the upper outlet of the wet scrubbing tower, which can remove the liquid water droplets carried in the flue gas, and the demisting effect reaches that the moisture content of the outlet flue gas is not more than 50 mg / Nm 3 , and introduce the demisted flue gas into the GGH to realize the reheating and white smoke elimination of the flue gas and the comprehensive utilization of the internal heat energy of the system; after detection, finally, the desulfurization efficiency reaches 98.5%, the dechlorination efficiency reaches 99.8%, the dust removal efficiency is more than 99.9%, and the denitrification efficiency is 92.0%.

[0067] Example 2

[0068] The cremation tail gas (450 °C) discharged from the underground flue outlets of multiple cremators is sent into the summary flue by the corresponding pre-positioned high-temperature fans 10 respectively, and then is transported to the combustion device 20 (internal circulation regenerative combustion system) for secondary combustion, and the temperature of the cremation tail gas is raised to 950 °C and stays for 3 seconds to obtain the combustion tail gas, and the above combustion tail gas is respectively heat-exchanged with the subsequent combustion-supporting gas and cremation tail gas to realize partial heat energy recycling.

[0069] Transport the heat-exchanged combustion tail gas to the quenching device 30 for cooling. After quenching, the combustion tail gas is cooled from 580 °C to 250 °C to obtain the cooled gas.

[0070] Send the cooled gas into the acid gas removal unit 50, and fully contact with the dry powder of the alkaline deacidifying agent NaHCO3 (650 mesh) and the adsorbent activated carbon sprayed in the acid gas removal device 52 (dry deacidification reactor). Then, the dust-containing tail gas after desulfurization enters the dust removal device 42 (bag filter) for further dust removal to obtain the primary purified gas. The temperature of the primary purified gas is 180 °C.

[0071] Then transport the above-mentioned primary purified tail gas at 180 °C to the catalytic denitrification device 63 (SCR catalyst) for catalytic denitrification reaction to obtain the secondary purified tail gas, where the sulfur dioxide content in the secondary purified tail gas is less than 50 mg / Nm 3 .

[0072] Use NaOH alkaline solution to further deeply absorb the acidic gases in the flue gas in the wet scrubbing tower. There is a demisting device at the upper outlet of the wet scrubbing tower, which can remove the liquid water droplets carried in the flue gas, and the demisting effect reaches that the moisture content of the outlet flue gas is not more than 50 mg / Nm 3, and introduce the post-dehumidification flue gas into the GGH to realize the reheating and white-out elimination of the flue gas and the comprehensive utilization of the internal heat energy of the system; after detection, the final desulfurization efficiency reaches 98.5%, the dechlorination efficiency reaches 99.0%, the dust removal efficiency is above 99.9%, and the denitrification efficiency is 92.0%.

[0073] Example 3

[0074] The cremation tail gas (450°C) discharged from the underground flue outlets of multiple cremators is sent into the summary flue by the corresponding pre-stage high-temperature fans 10 respectively, and then transported to the combustion device 20 (internal circulation regenerative combustion system) for secondary combustion, and the temperature of the cremation tail gas is raised to 950°C and stays for 3 seconds to obtain the combustion tail gas, and the above combustion tail gas is respectively heat-exchanged with the subsequent combustion-supporting gas and cremation tail gas to realize partial heat energy recycling.

[0075] Transport the heat-exchanged combustion tail gas to the quenching device 30 for cooling, and the temperature of the quenched combustion tail gas drops from 550°C to 220°C to obtain the cooling gas.

[0076] Send the cooling gas into the acid gas removal unit 50, and fully contact with the sprayed alkaline deacidifying agent Ca(OH)2 (650 mesh) dry powder and adsorbent activated carbon in the acid gas removal device 52 (dry deacidification reactor), and then the dust-containing tail gas after desulfurization enters the dust removal device 42 (bag filter) for further dust removal to obtain the primary purified gas. The temperature of the primary purified gas is 180°C.

[0077] Then transport the above-mentioned 180°C primary purified tail gas to the catalytic denitrification device 63 (SCR catalyst) for catalytic denitrification reaction to obtain the secondary purified tail gas, and the sulfur dioxide content in the secondary purified tail gas is less than 50mg / Nm 3 .

[0078] Use Ca(OH)2 alkaline solution to further deeply absorb the acid gas in the flue gas in the wet scrubbing tower. An atomizing device is provided at the upper outlet of the wet scrubbing tower, which can remove the liquid water droplets carried in the flue gas, and the atomizing effect reaches that the moisture content of the outlet flue gas is not more than 50mg / Nm 3 , and introduce the post-dehumidification flue gas into the GGH to realize the reheating and white-out elimination of the flue gas and the comprehensive utilization of the internal heat energy of the system; after detection, the final desulfurization efficiency reaches 97.5%, the dechlorination efficiency reaches 99.0%, the dust removal efficiency is above 99.9%, and the denitrification efficiency is 92.0%.

[0079] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects: adopting the above purification system can greatly improve the removal rates of acid gas and nitrogen oxides in the cremation tail gas, reduce the content of dioxins, and the dust content in the purified tail gas is relatively low.

[0080] It should be noted that the terms "first", "second", etc. in the description and claims of this application are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those described herein, for example.

[0081] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A purification system for cremation exhaust gas, characterized in that, The purification system includes: A blower (10) which is provided with an incineration tail gas inlet and an incineration tail gas outlet; A combustion device (20) which is provided with a first feed port (201), a second feed port (202) and a combustion tail gas outlet (204), wherein the first feed port (201) is communicated with the incineration tail gas outlet, and the second feed port (202) is used for conveying fuel and combustion-supporting gas; A quenching device (30) which is provided with a refrigerant inlet, a combustion tail gas inlet and a cooling gas outlet, and the combustion tail gas inlet is connected with the combustion tail gas outlet (204); An acid gas removal unit (50) which is provided with a cooling gas inlet, an alkaline acid removal agent inlet and a primary purified gas outlet, and the cooling gas inlet is communicated with the cooling gas outlet for removing acid gas in the cooling gas; and A catalytic denitrification unit (60) which is provided with a catalyst inlet, a reducing agent inlet, a primary purified gas inlet and a purified tail gas outlet, and the primary purified gas inlet is communicated with the primary purified gas outlet through a primary purified gas conveying pipeline; The purification system further includes a pressurizing device (70) which is arranged on the primary purified gas conveying pipeline; The purification system further includes a flue gas heat exchange device (80) which is used for heating up the primary purified tail gas discharged from the pressurizing device (70); The combustion device (20) includes: A primary heat exchange device (21) which is used for exchanging heat between the combustion tail gas and the incineration tail gas; A combustion chamber (22) which is used for burning the incineration tail gas processed by the primary heat exchange device (21) to obtain the combustion tail gas; and A secondary heat exchange device (23) which is used for exchanging heat between the combustion tail gas and the combustion-supporting gas; The purification system includes an adsorption and dust removal device (40) which is arranged on the flow path between the quenching device (30) and the acid gas removal unit (50) for removing dioxins and heavy metal elements in the cooling gas; The adsorption and dust removal device (40) includes: An adsorption device (41) which is provided with the cooling gas inlet and a dust-containing tail gas outlet; A dust removal device (42) which is provided with a dust-containing tail gas inlet and the primary purified gas outlet, the cooling gas inlet is communicated with the cooling gas outlet, and the dust-containing tail gas outlet is communicated with the dust-containing tail gas inlet; The blower (10) is a high-temperature blower.

2. The purification system according to claim 1, wherein The acid gas removal unit (50) includes: An alkaline acid removal agent supply device (51) which is provided with an alkaline acid removal agent supply port; Acid gas removal device (52), the acid gas removal device (52) is provided with the cooling gas inlet, the alkaline deacidifying agent inlet and the primary purified gas outlet, and the alkaline deacidifying agent inlet is communicated with the alkaline deacidifying agent supply port.

3. The purification system according to claim 1 or 2, characterized in that, The catalytic denitrification unit (60) includes: A catalyst supply device (61), the catalyst supply device (61) is provided with a catalyst supply port; A reducing agent supply device (62), the reducing agent supply device (62) is provided with a reducing agent supply port; A catalytic denitrification device (63), the catalytic denitrification device (63) is provided with the catalyst inlet, the reducing agent inlet, the primary purified gas inlet and the purified gas outlet, the catalyst inlet is communicated with the catalyst supply port, and the reducing agent inlet is communicated with the reducing agent supply port.

4. The purification system according to claim 1, characterized in that, The purification system further includes an alkali washing device (90), and the alkali washing device (90) is used for alkali washing the tail gas discharged from the purified gas outlet.

5. A purification method for cremation tail gas, characterized in that, Using the purification system for cremation tail gas according to any one of claims 1 to 4, the purification method includes: Accelerating the cremation tail gas by a fan and burning it with fuel and combustion-supporting gas to obtain combustion tail gas; Quenching the combustion tail gas to obtain cooling gas; Removing the acid gas in the cooling gas to obtain primary purified gas; Under the action of a catalyst, carrying out a catalytic denitrification reaction on the primary purified gas and a reducing agent to obtain purified tail gas; Between the step of removing the acid gas in the cooling gas and the catalytic denitrification reaction step, the purification method further includes: pressurizing the primary purified gas; Cooling the primary purified gas after the pressurization treatment, and at the same time heating the purified tail gas; The combustion process further includes heat exchange of the combustion tail gas with the combustion-supporting gas and the cremation tail gas conveyed by the fan in sequence.

6. The purification method according to claim 5, characterized in that, The step of removing the acid gas in the cooling gas includes: reacting an alkaline deacidifying agent with the acid gas in the cooling gas to remove the acid gas in the cooling gas; The alkaline deacidifying agent is selected from one or more of the group consisting of sodium bicarbonate, calcium hydroxide or quicklime.

7. The purification method according to claim 6, characterized in that, The temperature of the combustion process is 850 - 900 °C, and the time is 2 - 3 s.

8. The purification method according to any one of claims 5 to 7, characterized in that, Reducing the temperature of the combustion tail gas to 550 °C.

9. The purification method according to claim 8, characterized in that, The quenching step includes quenching the combustion tail gas with a mixture of water and compressed air as a refrigerant. After the quenching step, the temperature of the combustion tail gas is 200 - 230 °C.

10. The purification method according to claim 8, characterized in that, Before the step of removing the acid gas in the cooling gas, the purification method further includes: adsorbing the cooling gas with an adsorbent, and then performing dust removal treatment; The adsorbent is activated carbon.

11. The purification method according to claim 8, characterized in that The catalyst is selected from one or more of the group consisting of V2O5, WO3 and TiO2; the reducing agent is selected from one or more of the group consisting of ammonia water, urea and liquid ammonia.

12. The purification method according to claim 5, characterized in that, The purification method further includes: the temperatures of the purified tail gas and the primary purified gas are 50 - 140 °C.

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