Integrated dust removal and desulfurization device and method for coal water slurry flue gas

Abstract

The application provides a water-coal-slurry flue gas dust removal and desulfurization integrated purification device and purification method. The purification device comprises a flue gas waste heat condensation recovery system and a flue gas washing purification system. The flue gas waste heat condensation recovery system has a water-coal-slurry flue gas inlet. The flue gas waste heat condensation recovery system is used for cooling and dust removal treatment of the water-coal-slurry flue gas, and obtains cooled and dust-removed flue gas, a fly-ash slurry desulfurizer comprising condensed water and fly ash. The inlet of the flue gas washing purification system is connected with the outlet of the flue gas waste heat condensation recovery system. The flue gas washing purification system is used for desulfurization treatment of the cooled and dust-removed flue gas by using the fly-ash slurry desulfurizer obtained by the flue gas waste heat condensation recovery system, and obtains purified flue gas. The above purification method realizes water-coal-slurry flue gas dust removal and desulfurization integration, reduces flue gas purification cost, improves the economic benefit of the boiler, and has a dust removal efficiency of more than 99% and a desulfurization rate of more than 97%.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water coal slurry flue gas purification, in particular to a water coal slurry flue gas dust removal and desulfurization integrated purification device and purification method. BACKGROUND

[0002] Water coal slurry is a liquid coal-based fuel prepared by mixing, grinding and preparing coal, water and additives according to a certain proportion, and is divided into vaporized water coal slurry and fuel water coal slurry according to different uses.

[0003] In the current flue gas purification technology, flue gas dust removal mainly includes electrostatic dust removal, wet dust removal and bag dust removal, and desulfurization is divided into wet desulfurization and dry desulfurization. Flue gas dust removal and desulfurization are carried out in steps. The existing water coal slurry flue gas purification technology is completely designed and constructed according to the coal-fired boiler, without corresponding technical development according to the characteristics of high water content in water coal slurry flue gas and active calcium oxide in fly ash. The integrated dust removal and desulfurization cannot be realized. Although the relevant emission standard requirements can be met, the equipment investment cost is high, the desulfurization reagent consumption is large, the operation cost is high, and the economic benefit of the boiler enterprise is reduced. SUMMARY

[0004] The main purpose of the present application is to provide a water coal slurry flue gas dust removal and desulfurization integrated purification device and purification method, so as to solve the problems of high investment cost of water coal slurry flue gas purification equipment, large desulfurization reagent consumption and high operation cost in the prior art.

[0005] In order to achieve the above purpose, according to one aspect of the present application, a water coal slurry flue gas dust removal and desulfurization integrated purification device is provided. The purification device includes a flue gas waste heat condensation recovery system and a flue gas washing purification system. The flue gas waste heat condensation recovery system has a water coal slurry flue gas inlet. The flue gas waste heat condensation recovery system is used for cooling and dust removal treatment of the water coal slurry flue gas, to obtain cooled and dust-removed flue gas, fly ash slurry desulfurizer including condensed water and fly ash. The inlet of the flue gas washing purification system is connected with the outlet of the flue gas waste heat condensation recovery system. The flue gas washing purification system is used for desulfurization treatment of the cooled and dust-removed flue gas by using the fly ash slurry desulfurizer obtained by the flue gas waste heat condensation recovery system, to obtain purified flue gas.

[0006] Further, the flue gas waste heat condensing recovery system comprises a flue, a coil heat exchanger, a cyclone dust removal condenser and a water cooling cavity. The flue is used for the circulation of the coal water slurry flue gas. The coil heat exchanger is arranged in the flue. The coil of the coil heat exchanger is provided with primary heat exchange boiler water. The coil heat exchanger is used for primary heat exchange treatment of the coal water slurry flue gas to obtain primary cooling flue gas and secondary heat exchange boiler water. The inlet of the cyclone dust removal condenser is connected with the outlet of the flue. The cyclone dust removal condenser is used for dust removal treatment of the primary cooling flue gas to obtain dust removal flue gas and fly ash. The water cooling cavity is arranged on the outer side wall of the cyclone dust removal condenser. The water cooling cavity is provided with a boiler water inlet and a boiler water outlet. The boiler water outlet is connected with the inlet of the coil heat exchanger. The boiler water in the water cooling cavity is used for secondary heat exchange treatment of the dust removal flue gas in the cyclone dust removal condenser to obtain cooling dust removal flue gas, primary heat exchange boiler water and condensed water. The primary heat exchange boiler water enters the coil heat exchanger through the boiler water outlet of the water cooling cavity. The fly ash and the condensed water are mixed to form fly ash slurry desulfurizer which is accumulated at the bottom of the cyclone dust removal condenser. Optionally, the outlet of the coil heat exchanger is connected with an external boiler to use the secondary heat exchange boiler water as boiler water.

[0007] Further, the flue gas washing and purifying system comprises a desulfurization washing tower and an atomizing spraying device. The upper end inlet of the desulfurization washing tower is connected with the bottom outlet of the cyclone dust removal condenser. The lower end inlet of the desulfurization washing tower is connected with the top outlet of the cyclone dust removal condenser. The desulfurization washing tower is used for desulfurization treatment of the cooling dust removal flue gas and the fly ash slurry desulfurizer in the cyclone dust removal condenser to obtain purified flue gas and calcium sulfite. The atomizing spraying device is arranged at the upper end of the desulfurization washing tower. The inlet of the atomizing spraying device is connected with the bottom outlet of the cyclone dust removal condenser. The atomizing spraying device is used for spraying the fly ash slurry desulfurizer into the desulfurization washing tower in the form of mist droplets to reversely contact with the cooling dust removal flue gas. Optionally, the lower end of the desulfurization washing tower is provided with an oxygen-containing gas inlet. The oxygen-containing gas is introduced into the desulfurization washing tower to oxidize the calcium sulfite.

[0008] Further, the purifying device further comprises a buffer stirring system. The buffer stirring system comprises a buffer stirring tank, a first slurry conveying pump and a second slurry conveying pump. The buffer stirring tank is used for stirring and mixing the fly ash slurry desulfurizer. The first slurry conveying pump is arranged on the pipeline connecting the bottom outlet of the cyclone dust removal condenser with the inlet of the buffer stirring tank. The first slurry conveying pump is used for conveying the fly ash slurry desulfurizer into the buffer stirring tank. The second slurry conveying pump is arranged on the pipeline connecting the outlet of the buffer stirring tank with the upper end inlet of the desulfurization washing tower. The second slurry conveying pump is used for conveying the stirred and mixed fly ash slurry desulfurizer into the interior of the desulfurization washing tower.

[0009] According to another aspect of the present application, a purification method for dust removal and desulfurization integration of coal water slurry flue gas is provided, which comprises the following steps: S1, performing cooling treatment on the coal water slurry flue gas to obtain condensed water and cooled flue gas; S2, performing dust removal treatment on the cooled flue gas to obtain cooled and dust-removed flue gas and fly ash, and mixing the fly ash with the condensed water to obtain fly ash slurry desulfurizer; and S3, performing desulfurization treatment on the cooled and dust-removed flue gas by using the fly ash slurry desulfurizer.

[0010] Further, the cooling process comprises: performing primary heat exchange between the coal water slurry flue gas and primary heat exchange boiler water to obtain primary cooled flue gas and secondary heat exchange boiler water; and performing secondary heat exchange between the primary cooled flue gas and the boiler water to obtain the primary heat exchange boiler water, condensed water and cooled flue gas.

[0011] Further, the flow rate of the coal water slurry flue gas is 600000-1000000 m 3 / h, and preferably, the temperature of the coal water slurry flue gas is 130-160℃.

[0012] Further, the flow rate of the boiler water is 300-500 m 3 / h.

[0013] Further, the fly ash slurry desulfurizer is reacted with the cooled and dust-removed flue gas in an oxygen-containing atmosphere.

[0014] Further, the secondary heat exchange boiler water is used as boiler water.

[0015] According to the technical solution of the present application, since the fuel coal water slurry is mainly used as boiler fuel for combustion, the coal water slurry flue gas generated after combustion contains not only the same emissions as the original coal combustion, but also fly ash with a large water content (about 40%) and part of active calcium oxide. The present application utilizes the large amount of water vapor and active calcium oxide in the coal water slurry flue gas to form a high-efficiency desulfurizer, i.e. fly ash slurry desulfurizer. Specifically, the present application uses the above-mentioned purification device for dust removal and desulfurization integration of coal water slurry flue gas. Firstly, the waste heat in the coal water slurry flue gas is recovered by the flue gas waste heat condensation recovery system, and at the same time, the cooled and dust-removed flue gas and condensed water are obtained. The condensed water and the fly ash obtained by dust removal treatment form a fly ash slurry desulfurizer. Therefore, the fly ash slurry desulfurizer generated by the flue gas waste heat condensation recovery system is directly used in the flue gas washing and purification system to perform desulfurization treatment on the cooled and dust-removed flue gas, and purified flue gas is obtained. The desulfurization treatment principle is wet desulfurization, which has a similar mechanism to calcium-based desulfurization: CaO + H2O = Ca(OH)2, Ca(OH)2 + SO2 = CaSO3 + H2O, 2CaSO3 + O2 = 2CaSO4. The above purification method realizes the integration of dust removal and desulfurization of coal water slurry flue gas, reduces the cost of flue gas purification, improves the economic benefit of the boiler, and has a dust removal efficiency of more than 99% and a desulfurization rate of more than 97%. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0017] Figure 1 A schematic diagram of an integrated dust removal and desulfurization purification device for coal-water slurry flue gas according to Embodiment 1 of the present invention is shown.

[0018] The above figures include the following reference numerals:

[0019] 1. Flue; 2. Coil heat exchanger; 3. Cyclone dust collector condenser; 4. Water-cooled chamber; 5. Desulfurization scrubbing tower; 6. Atomizing spray device; 7. Buffer mixing tank; 8. First slurry pump; 9. Second slurry pump; 10. Flue gas waste heat condensation recovery system; 20. Flue gas scrubbing and purification system. Detailed Implementation

[0020] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0021] As analyzed in the background section of this application, the prior art has identified problems. In order to solve these problems, this application provides an integrated dust removal and desulfurization purification device and method for coal-water slurry flue gas.

[0022] In a typical embodiment of this application, an integrated dust removal and desulfurization purification device for coal-water slurry flue gas is provided, such as... Figure 1 As shown, the purification device includes a flue gas waste heat condensation and recovery system 10 and a flue gas scrubbing and purification system 20. The flue gas waste heat condensation and recovery system 10 has a water-coal slurry flue gas inlet. The flue gas waste heat condensation and recovery system 10 is used to cool and remove dust from the water-coal slurry flue gas to obtain cooled and dust-removed flue gas and fly ash slurry desulfurizing agent including condensate and fly ash. The inlet of the flue gas scrubbing and purification system 20 is connected to the outlet of the flue gas waste heat condensation and recovery system 10. The flue gas scrubbing and purification system 20 is used to desulfurize the cooled and dust-removed flue gas using the fly ash slurry desulfurizing agent obtained from the flue gas waste heat condensation and recovery system 10 to obtain purified flue gas.

[0023] Since the coal water slurry is mainly used as boiler fuel, the flue gas generated after combustion contains not only the same emissions as the original coal combustion, but also a large amount of water (about 40%) and part of active calcium oxide in the fly ash. The present application utilizes the large amount of water vapor and active calcium oxide in the coal water slurry flue gas to form a high-efficiency desulfurizer, i.e. fly ash slurry desulfurizer. Specifically, the present application uses the above-mentioned dust removal and desulfurization integrated purification device of the coal water slurry flue gas. Firstly, the flue gas waste heat condensation recovery system 10 recovers the waste heat in the coal water slurry flue gas and obtains the cooled and dust-removed flue gas and condensed water at the same time. The condensed water and the fly ash obtained by dust removal form a fly ash slurry desulfurizer. Therefore, the fly ash slurry desulfurizer generated by the flue gas waste heat condensation recovery system 10 is directly used to desulfurize the cooled and dust-removed flue gas in the flue gas washing and purification system 20, and the purified flue gas is obtained. The desulfurization principle is wet desulfurization, which has a similar mechanism to calcium-based desulfurization: CaO + H2O = Ca(OH)2, Ca(OH)2 + SO2 = CaSO3 + H2O, 2CaSO3 + O2 = 2CaSO4. The above purification method realizes the integration of dust removal and desulfurization of the coal water slurry flue gas, reduces the cost of flue gas purification, improves the economic benefit of the boiler, and the dust removal efficiency is greater than 99% and the desulfurization rate is more than 97%.

[0024] In an embodiment of the present application, the above-mentioned flue gas waste heat condensation recovery system 10 comprises a flue 1, a coil heat exchanger 2, a cyclone dust removal condenser 3 and a water cooling cavity 4. The flue 1 is used for the flow of the coal water slurry flue gas. The coil heat exchanger 2 is arranged in the flue 1, and the coil of the coil heat exchanger 2 is provided with primary heat exchange boiler water. The coil heat exchanger 2 is used for primary heat exchange treatment of the coal water slurry flue gas to obtain primary cooled flue gas and secondary heat exchange boiler water. The inlet of the cyclone dust removal condenser 3 is connected with the outlet of the flue 1. The cyclone dust removal condenser 3 is used for dust removal treatment of the primary cooled flue gas to obtain dust-removed flue gas and fly ash. The water cooling cavity 4 is arranged on the outer side wall of the cyclone dust removal condenser 3. The water cooling cavity 4 has a boiler water inlet and a boiler water outlet. The boiler water outlet is connected with the inlet of the coil heat exchanger 2. The boiler water in the water cooling cavity 4 is used for secondary heat exchange treatment of the dust-removed flue gas in the cyclone dust removal condenser 3 to obtain cooled and dust-removed flue gas, primary heat exchange boiler water and condensed water. The primary heat exchange boiler water enters the coil heat exchanger 2 through the boiler water outlet of the water cooling cavity 4. The fly ash and the condensed water are mixed to form a fly ash slurry desulfurizer which is accumulated at the bottom of the cyclone dust removal condenser 3. Optionally, the outlet of the coil heat exchanger 2 is connected with an external boiler to use the secondary heat exchange boiler water as boiler water.

[0025] The water-coal slurry flue gas passes through the flue 1 and the cyclone dust removal condenser 3 in sequence, and the corresponding boiler water passes through the water-cooling cavity 4 and the coil heat exchanger 2 in sequence. The water-coal slurry flue gas and the boiler water flow reversely. In this process, the lower-temperature primary heat exchange boiler water in the coil heat exchanger 2 and the higher-temperature water-coal slurry flue gas in the flue 1 are subjected to primary heat exchange treatment, so that the temperature of the obtained primary cooling flue gas is reduced to the vicinity of the dew point. The lower-temperature boiler water in the water-cooling cavity 4 and the higher-temperature primary cooling flue gas in the cyclone dust removal condenser 3 are subjected to secondary heat exchange treatment, so that the temperature of the obtained blocked cooling and dust removal flue gas is lower than the dew point and is condensed into condensed water. Under the action of gravity, the condensed water is gathered along the inner wall of the cyclone dust removal condenser 3 and is collected at the bottom of the cone of the cyclone dust removal condenser 3. At the same time, the fly ash in the primary cooling flue gas is separated out by the separation and sedimentation of the cyclone dust removal condenser 3 and is mixed with the condensed water to form a fly ash desulfurizer. The above-mentioned primary heat exchange treatment and secondary heat exchange treatment convert the residual heat in the water-coal slurry flue gas into the heat of the boiler water. The secondary heat exchange boiler water can be discharged from the outlet of the coil heat exchanger 2 and directly used as boiler water, so that the energy consumption is greatly reduced.

[0026] In an embodiment of the present application, the above-mentioned flue gas washing and purifying system 20 comprises a desulfurization washing tower 5 and an atomizing spraying device 6. The upper end inlet of the desulfurization washing tower 5 is connected with the bottom outlet of the cyclone dust removal condenser 3, and the lower end inlet of the desulfurization washing tower 5 is connected with the top outlet of the cyclone dust removal condenser 3. The desulfurization washing tower 5 is used for desulfurization treatment of the cooling and dust removal flue gas and the fly ash slurry desulfurizer in the cyclone dust removal condenser 3, so as to obtain purified flue gas and calcium sulfite. The atomizing spraying device 6 is arranged at the upper end of the desulfurization washing tower 5, and the inlet of the atomizing spraying device 6 is connected with the bottom outlet of the cyclone dust removal condenser 3. The atomizing spraying device 6 is used for spraying the fly ash slurry desulfurizer into the desulfurization washing tower 5 in the form of mist droplets and reversely contacting with the cooling and dust removal flue gas. Optionally, the lower end of the desulfurization washing tower 5 is provided with an oxygen-containing gas inlet, which is used for introducing oxygen-containing gas into the desulfurization washing tower 5 to oxidize the calcium sulfite.

[0027] The fly ash desulfurizer atomized by the atomizing spraying device 6 enters the desulfurization washing tower 5 and chemically reacts with the cooling and dust removal flue gas. The generated calcium sulfite is collected at the bottom of the desulfurization washing tower 5. The oxygen-containing gas (such as air) can be introduced into the bottom of the desulfurization washing tower 5 by an oxidation fan, so as to oxidize the generated calcium sulfite into calcium sulfate to complete the desulfurization purification. The purified flue gas after desulfurization purification is introduced into a chimney by the outlet and is discharged into the atmosphere. The fly ash desulfurizer after reaction is transported into a recovery pool by a slurry pump from the bottom of the desulfurization washing tower 5 and is recovered.

[0028] In an embodiment of the present application, the above-mentioned purification device further comprises a buffer stirring system 30, which comprises a buffer stirring tank 7, a first slurry pump 8 and a second slurry pump 9. The buffer stirring tank 7 is used for stirring and mixing the fly ash slurry desulfurizer. The first slurry pump 8 is arranged on a pipeline connecting the bottom outlet of the cyclone dust removal condenser 3 and the inlet of the buffer stirring tank 7, and is used for conveying the fly ash slurry desulfurizer into the buffer stirring tank 7. The second slurry pump 9 is arranged on a pipeline connecting the outlet of the buffer stirring tank 7 and the upper inlet of the desulfurization washing tower 5, and is used for conveying the stirred and mixed fly ash slurry desulfurizer into the desulfurization washing tower 5.

[0029] The first slurry pump 8 can continuously send the fly ash slurry desulfurizer to the buffer stirring tank 7 for stirring and homogenization, and the second slurry pump 9 can continuously convey the stirred and homogenized fly ash slurry desulfurizer into the desulfurization washing tower 5 for desulfurization treatment.

[0030] In another typical embodiment of the present application, a purification method for dust removal and desulfurization of coal water slurry flue gas is provided, which comprises the following steps: S1, cooling the coal water slurry flue gas to obtain condensed water and cooled flue gas; S2, dust removal treatment of the cooled flue gas to obtain cooled and dust-removed flue gas and fly ash, and mixing the fly ash with the condensed water to obtain a fly ash slurry desulfurizer; and S3, desulfurization treatment of the cooled and dust-removed flue gas by using the fly ash slurry desulfurizer.

[0031] Since the coal water slurry is mainly used as boiler fuel for combustion, the coal water slurry flue gas produced after combustion contains not only the same emissions as the original coal combustion, but also fly ash with a high water content (about 40%) and part of active calcium oxide. The present application utilizes the large amount of water vapor and active calcium oxide in the coal water slurry flue gas to form a high-efficiency desulfurizer, i.e. a fly ash slurry desulfurizer. Specifically, the above-mentioned purification method for dust removal and desulfurization of coal water slurry flue gas is used to recover the waste heat in the coal water slurry flue gas to obtain cooled and dust-removed flue gas and condensed water. The condensed water and the fly ash obtained by dust removal treatment form a fly ash slurry desulfurizer, which is directly used for desulfurization treatment of the cooled and dust-removed flue gas to obtain purified flue gas. The desulfurization treatment principle is wet desulfurization, which has a similar mechanism to calcium-based desulfurization: CaO + H2O = Ca(OH)2, Ca(OH)2 + SO2 = CaSO3 + H2O, 2CaSO3 + O2 = 2CaSO4. The above-mentioned purification method realizes the integration of dust removal and desulfurization of coal water slurry flue gas, reduces the cost of flue gas purification, improves the economic benefit of the boiler, and has a dust removal efficiency of more than 99% and a desulfurization rate of more than 97%.

[0032] In an embodiment of the present application, the process of temperature reduction comprises: carrying out primary heat exchange between the coal water slurry flue gas and the primary heat exchange boiler water to obtain primary temperature-reduced flue gas and secondary heat exchange boiler water; carrying out secondary heat exchange between the primary temperature-reduced flue gas and the boiler water to obtain the primary heat exchange boiler water, condensed water and temperature-reduced flue gas.

[0033] The use of boiler water as the cooling agent can reduce the emission temperature of the purified flue gas to below 50°C, which not only increases the waste heat recovery of the high-temperature flue gas of the boiler, realizes the preheating of the boiler water, improves the thermal efficiency of the boiler and reduces the energy waste, but also absorbs the pollutants in the coal water slurry flue gas, and preliminarily realizes the flue gas purification.

[0034] In an embodiment of the present application, the flow rate of the coal water slurry flue gas is preferably 600000-1000000m 3 / h, and the temperature of the coal water slurry flue gas is preferably 130-160°C.

[0035] The preferred flow rate and temperature of the coal water slurry flue gas are helpful to control the heat exchange process between the coal water slurry flue gas and the boiler water, so as to maintain the temperature of the primary temperature-reduced flue gas near the dew point and generate a certain amount of cooling water during the secondary heat exchange process to obtain the fly ash slurry desulfurizer.

[0036] The flow rate of the boiler water is preferably 300-500m 3 / h, and the control of the flow rate of the boiler water is helpful to maintain the temperature of the primary temperature-reduced flue gas near the dew point, and the secondary heat exchange boiler water is discharged from the outlet of the coil heat exchanger and directly enters the boiler.

[0037] In an embodiment of the present application, the fly ash slurry desulfurizer is reacted with the temperature-reduced dust removal flue gas in an oxygen-containing atmosphere.

[0038] In the oxygen-containing atmosphere, the calcium sulfite generated by the chemical reaction between the fly ash desulfurizer and the temperature-reduced dust removal flue gas can be further oxidized into calcium sulfate, which can be directly used as building materials.

[0039] The secondary heat exchange boiler water is preferably used as the boiler water, which is helpful to realize the preheating of the boiler water, improve the thermal efficiency of the boiler and reduce the energy waste.

[0040] The beneficial effects of the present application will be further illustrated in combination with the embodiments.

[0041] Embodiment 1

[0042] The coal water slurry (the total sulfur of the raw coal for slurry preparation is 0.35%) is combusted by a 3MW circulating fluidized bed boiler combustion test bench to generate coal water slurry flue gas and fly ash (the CaO2 content is 15-20%), which is purified by the coal water slurry flue gas dust and desulfurization integrated purification device shown in FIG. Figure 1 The coal water slurry flue gas (the flue gas temperature is 130°C, and the flow rate is 600000m3 (h) the primary desulfurization of the dust-removed flue gas is carried out in the desulfurization scrubber 5, the desulfurization scrubber 5 is connected to the water-cooled cavity 4 of the cyclone dust-removal condenser 3, and the desulfurization scrubber 5 is connected to the water-cooled cavity 4 of the cyclone dust-removal condenser 3 through the second slurry pump 9.

[0043] (h) the primary desulfurization of the dust-removed flue gas is carried out in the desulfurization scrubber 5, the desulfurization scrubber 5 is connected to the water-cooled cavity 4 of the cyclone dust-removal condenser 3, and the desulfurization scrubber 5 is connected to the water-cooled cavity 4 of the cyclone dust-removal condenser 3 through the second slurry pump 9. 3 (h) the primary desulfurization of the dust-removed flue gas is carried out in the desulfurization scrubber 5, the desulfurization scrubber 5 is connected to the water-cooled cavity 4 of the cyclone dust-removal condenser 3, and the desulfurization scrubber 5 is connected to the water-cooled cavity 4 of the cyclone dust-removal condenser 3 through the second slurry pump 9.

[0044] (h) the primary desulfurization of the dust-removed flue gas is carried out in the desulfurization scrubber 5, the desulfurization scrubber 5 is connected to the water-cooled cavity 4 of the cyclone dust-removal condenser 3, and the desulfurization scrubber 5 is connected to the water-cooled cavity 4 of the cyclone dust-removal condenser 3 through the second slurry pump 9.

[0045] From the above description, it can be seen that the above-mentioned embodiments of the present application achieve the following technical effects:

[0046] Since the fuel coal water slurry is mainly combusted as boiler fuel, the flue gas produced after combustion contains not only the same emissions as the original coal combustion, but also a large amount of water content (about 40%) and part of active calcium oxide in the fly ash. The present application utilizes the large amount of water vapor and active calcium oxide in the coal water slurry flue gas to form a high-efficiency desulfurizer, i.e. fly ash slurry desulfurizer. Specifically, the present application uses the above-mentioned dust removal and desulfurization integrated purification device of the coal water slurry flue gas. Firstly, the waste heat in the coal water slurry flue gas is recovered by the flue gas waste heat condensing recovery system, and at the same time, the cooled and dust-removed flue gas and condensed water are obtained. The condensed water and the fly ash obtained by dust removal form a fly ash slurry desulfurizer, so that the fly ash slurry desulfurizer produced by the flue gas waste heat condensing recovery system is directly used in the flue gas washing and purification system to desulfurize the cooled and dust-removed flue gas, and the purified flue gas is obtained. The desulfurization principle is wet desulfurization, and its mechanism is similar to that of calcium-based desulfurization: CaO + H2O = Ca(OH)2, Ca(OH)2 + SO2 = CaSO3 + H2O, 2CaSO3 + O2 = 2CaSO4. The above purification method realizes the integration of dust removal and desulfurization of the coal water slurry flue gas, reduces the cost of flue gas purification, improves the economic benefit of the boiler, and the dust removal efficiency is greater than 99%, and the desulfurization rate is more than 97%.

[0047] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A purification device integrating dust removal and desulfurization of coal-water slurry flue gas, characterized in that, The purification device includes: The flue gas waste heat condensation and recovery system (10) has the water-coal slurry flue gas inlet. The flue gas waste heat condensation and recovery system (10) is used to cool and remove dust from the water-coal slurry flue gas to obtain cooled and dust-removed flue gas and fly ash slurry desulfurizer including condensate and fly ash. The flue gas waste heat condensation and recovery system (10) includes: Flue (1) is used for the circulation of the flue gas from the coal-water slurry. A coil heat exchanger (2) is installed in the flue (1). The coil of the coil heat exchanger (2) is filled with primary heat exchange boiler water. The coil heat exchanger (2) is used to perform primary heat exchange treatment on the coal-water slurry flue gas to obtain primary cooled flue gas and secondary heat exchange boiler water. Cyclone dust collector condenser (3), the inlet of which is connected to the outlet of the flue (1), the cyclone dust collector condenser (3) is used to perform the dust removal treatment on the primary cooling flue gas to obtain dust-removed flue gas and fly ash; A water-cooled chamber (4) is disposed on the outer wall of the cyclone dust collector condenser (3). The water-cooled chamber (4) has a boiler water inlet and a boiler water outlet. The boiler water outlet is connected to the inlet of the coil heat exchanger (2). The boiler water in the water-cooled chamber (4) is used to perform secondary heat exchange treatment on the dust-collecting flue gas in the cyclone dust collector condenser (3) to obtain the cooled dust-collecting flue gas, the primary heat exchange boiler water, and the condensate. The primary heat exchange boiler water enters the coil heat exchanger (2) through the boiler water outlet of the water-cooled cavity (4); The fly ash and the condensate are mixed to form the fly ash slurry desulfurizing agent, which accumulates at the bottom of the cyclone dust collector condenser (3); the flue gas scrubbing and purification system (20) has its inlet connected to the outlet of the flue gas waste heat condensation recovery system (10). The flue gas scrubbing and purification system (20) is used to desulfurize the cooled and dust-removing flue gas using the fly ash slurry desulfurizing agent obtained from the flue gas waste heat condensation recovery system (10) to obtain purified flue gas.

2. The purification device according to claim 1, characterized in that, The outlet of the coil heat exchanger (2) is connected to an external boiler and is used to use the secondary heat exchange boiler water as boiler water.

3. The purification device according to claim 2, characterized in that, The flue gas scrubbing and purification system (20) includes: The desulfurization scrubbing tower (5) has its upper inlet connected to the bottom outlet of the cyclone dust collector condenser (3) and its lower inlet connected to the top outlet of the cyclone dust collector condenser (3). The desulfurization scrubbing tower (5) is used to desulfurize the cooled and dust-removing flue gas and the fly ash slurry desulfurizing agent in the cyclone dust collector condenser (3) to obtain the purified flue gas and calcium sulfite. The atomizing spray device (6) is located at the upper end of the desulfurization scrubbing tower (5), and its inlet is connected to the bottom outlet of the cyclone dust collector condenser (3). The atomizing spray device (6) is used to spray the fly ash slurry desulfurizing agent into the desulfurization scrubbing tower (5) in the form of droplets and make it contact the cooling and dust removal flue gas in the opposite direction.

4. The purification device according to claim 3, characterized in that, The lower end of the desulfurization scrubbing tower (5) is provided with an oxygen-containing gas inlet for introducing the oxygen-containing gas into the desulfurization scrubbing tower (5) to oxidize the calcium sulfite.

5. The purification device according to claim 3, characterized in that, The purification device further includes a buffer stirring system (30), which includes: A buffer mixing tank (7) is used to mix the fly ash slurry desulfurizer. The first slurry pump (8) is installed on the pipeline connecting the bottom outlet of the cyclone dust collector condenser (3) and the inlet of the buffer mixing tank (7) to transport the fly ash slurry desulfurizer into the buffer mixing tank (7). The second slurry pump (9) is installed on the pipeline connecting the outlet of the buffer mixing tank (7) and the upper inlet of the desulfurization washing tower (5) to transport the mixed fly ash slurry desulfurizing agent into the desulfurization washing tower (5).

6. A method for integrating dust removal and desulfurization of coal-water slurry flue gas using the purification device according to any one of claims 1 to 5, characterized in that, The purification method includes: Step S1: Cool the water-coal slurry flue gas to obtain condensate and cooled flue gas; The cooling process includes: The water-coal slurry flue gas is subjected to a primary heat exchange with the primary heat exchanger water to obtain primary cooling flue gas and secondary heat exchanger water. The primary cooling flue gas is subjected to secondary heat exchange with the boiler water to obtain the primary heat exchanged boiler water, the condensate, and the cooling flue gas; Step S2 involves treating the cooled flue gas with dust removal to obtain cooled and dust-removed flue gas and fly ash, and then mixing the fly ash with the condensate to obtain a fly ash slurry desulfurizing agent; and Step S3: The cooling and dust removal flue gas is desulfurized using the fly ash slurry desulfurizing agent.

7. The purification method according to claim 6, characterized in that, The flow rate of the coal-water slurry flue gas is 600,000~1,000,000 m³ / h. 3 / h.

8. The purification method according to claim 7, characterized in that, The temperature of the flue gas from the coal-water slurry is 130~160℃.

9. The purification method according to claim 6 or 7, characterized in that, The flow rate of the boiler water is 300~500m³. 3 / h.

10. The purification method according to claim 6 or 7, characterized in that, In an oxygen-containing atmosphere, the fly ash slurry desulfurizing agent is reacted with the cooled and dust-removing flue gas.

11. The purification method according to claim 6, characterized in that, The water from the secondary heat exchanger is used as boiler water.

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