Method for high efficiency combustion of sludge in a cement kiln

Abstract

The application provides a method for efficient combustion of sludge in a combined cement kiln, and belongs to the field of environmental protection; the device is composed of a sludge drying system, a sludge incineration system and a flue gas treatment system; harmful substances in the sludge can be fully combusted and decomposed in the high-temperature cement rotary kiln; heavy metals in the sludge ash can be fixed in the structure of cement clinker, thereby reducing secondary pollution to the environment; the sludge incineration rate is as high as 99.99%, and the VOCs content in the flue gas is only 5.5mg / m 3 After the sludge is disposed of by the cement kiln, the harmless and resourceful treatment of the sludge can be simultaneously achieved, the treatment and disposal of the sludge are organically combined with the cement production, the treatment cost of the sludge is saved, and the consumption of cement raw materials and fuel is reduced; meanwhile, the huge accommodation capacity of the cement industry for the sludge is incomparable to other treatment technologies.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of environmental protection, and particularly relates to a method for efficient combustion of sludge in a cement kiln. BACKGROUND

[0002] Sludge is complex in composition, different in nature and increasing in quantity year by year. Traditional sludge treatment and disposal processes (landfill, incineration and land use, etc.) have the disadvantages of large land occupation, secondary pollution and small treatment capacity, and are difficult to be sustainable. The cement waste co-processing process has the advantages of large waste treatment capacity, high reduction rate and complete harmless, and is increasingly valued, and is the development trend of solid waste treatment in the future.

[0003] CN202010489594.2 applies for a kind of city dry sludge cement kiln co-processing process, it relates to dry sludge treatment technical field. Sludge passes through sludge unloading bin and sludge travelling crane stock bin, after board feeder, then to tubular belt conveyor, then transported to transfer station, transfer station is equipped with sludge buffer bin, then after board feeder, by tubular belt conveyor to hoist, by hoist to kiln tail, after crushing to sludge small bin, after metering by quantitative feeder, through zip machine and fed into decomposition furnace and precombustion chamber for incineration disposal, most of toxic organic matter reaches complete decomposition, and a small amount of large particle sintered slag falls into rotary kiln from kiln tail updraft, and then calcined into cement clinker by rotary kiln system, completely realize the harmless disposal of sludge.

[0004] CN202020981721.6 applies for a kind of dry sludge cement kiln co-processing device, it includes sludge tank car, sludge unloading pit, travelling crane grab, sludge storage pit, sludge stock bin, board feeder, quantitative feeder, first U-shaped belt conveyor, crusher, vibrating screen, kiln tail hot disc furnace and second U-shaped belt conveyor, sludge tank car transports sludge to sludge unloading pit or sludge stock bin, sludge in sludge unloading pit is sent to sludge storage pit by travelling crane grab, sludge in sludge storage pit is sent to sludge stock bin by travelling crane grab, sludge stock bin is connected with quantitative feeder by board feeder, quantitative feeder is connected to crusher by first U-shaped belt conveyor, crusher is connected with vibrating screen, vibrating screen is connected with first U-shaped belt conveyor and second U-shaped belt conveyor respectively, and second U-shaped belt conveyor is connected to kiln tail hot disc furnace. The present application pre-treats dry sludge, and after crushing and screening, the particle uniformity is better, and the combustion is more sufficient.

[0005] CN201210011331.6 provides a method for co-processing fluorine-containing sludge in a cement kiln. The fluorine-containing sludge with a water content of 40% to 80% can be co-processed in a cement kiln, and the amount of sludge incorporated is about 1% to 5% of the total amount of cement raw materials. The method for co-processing provided by the present application is characterized by utilizing the waste heat tail gas of the cement kiln to dry the fluorine-containing sludge with a water content of 40% to 80%, so that the fluorine-containing sludge can be safely disposed of in the cement kiln, and the performance indicators of the produced cement meet the national standards. The present application regards the fluorine-containing sludge as a useful resource, which on the one hand safely disposes of the fluorine-containing sludge containing fluoride, and saves a large amount of land.

[0006] The above patents and prior art have the following disadvantages: 1) secondary pollution problem caused by flue gas generated by incineration: the waste gas generated by incineration of sludge may contain pollutants such as dioxin, nitrogen oxide and sulfur oxide; 2) treatment problem of fly ash and bottom slag generated after sludge incineration: the fly ash generated by sludge incineration is a hazardous waste, which needs to be disposed according to the requirements for disposal of hazardous waste; 3) high energy consumption: for sludge with high water content and low heat value, the heat consumption of incineration is high, and the treatment cost is relatively high. SUMMARY

[0007] In order to solve the above problems, the present application provides a method for efficient combustion of sludge in a combined cement kiln, and the device comprises a sludge drying system, a sludge incineration system and a flue gas treatment system.

[0008] Further, the sludge drying system: after the sludge is dewatered by a plate and frame filter press, the water content of the sludge is 50-60%; the water content of the dried sludge is 10-35%; and the fineness of the crushed and ground powder reaches the required 70-80 μm.

[0009] Further, the sludge incineration system: after the dried particles and gases are separated by a cyclone separator, they are sent into the cement kiln for incineration after being cooled by a screw; the amount of sludge powder incorporated is about 1% to 10% of the total amount of cement raw materials, and the amount of desulfurizing agent incorporated is about 0.01% to 0.3% of the total amount of cement raw materials.

[0010] Further, the flue gas treatment system: the high-temperature flue gas after incineration is used as a heat source to enter the sludge drying system to dry the sludge.

[0011] Further, the cement kiln controls the incineration temperature to be 950-1350℃, and the time to be 20-45 min.

[0012] Further, the solid waste residue after incineration is used as cement clinker.

[0013] Further, the wastewater generated during the production process contains certain pollutants, which is returned to the sludge drying system to achieve zero discharge of wastewater.

[0014] The application also includes a preparation method of the desulfurizer:

[0015] S1: according to the mass fraction, 150-200 parts of Mg(OH)2 is added to 1000-2000 parts of water, 5-10 parts of acryloxy silane is added, stirring reaction is carried out at 60-80℃ for 60-100 min, filtration is carried out, and drying is carried out;

[0016] S2: 30-50 parts of DMF and 3-7 parts of the acryl-modified Mg(OH)2 prepared in S1 are added to a reaction kettle, stirring is carried out for 20-50 min, then 5-12 parts of an organic amine is added, temperature control is carried out at 60-70℃, stirring is carried out for 60-120 min, then 0.05-3 parts of copper tetraaminophthalocyanine is added, and continues to react for 60-120 min, filtration is carried out, and drying is carried out, so that the desulfurizer is obtained.

[0017] Further, the organic amine is selected from N-methylmorpholine, N-ethylmorpholine and N,N'-dimethylpiperazine.

[0018] Further, the acryloxy silane includes 3-(methacryloyloxy)propyltrimethoxysilane (CAS number: 2530-85-0), acryloxy methyl trimethoxysilane (CAS number: 21134-38-3), methacryloyloxy propyl triethoxysilane (CAS number: 21142-29-0) and (acryloxy methyl) dimethyl methoxysilane (CAS number: 130771-16-3).

[0019] The core technical advantage of the application is that:

[0020] The amino-modified Mg(OH)2 is firstly added with acrylamide propyl dodecyl dimethyl ammonium bromide, and then the copper tetraaminophthalocyanine is added with the acrylamide propyl dodecyl dimethyl ammonium bromide.

[0021] The beneficial effects of using the application are that:

[0022] Compared with the prior art, the application has the following beneficial effects:

[0023] 1) The harmful substances in the sludge can be fully combusted and decomposed in the high-temperature cement rotary kiln;

[0024] 2) The rotary kiln is stable, the treatment capacity is large, and the quality of the cement product is not affected;

[0025] 3) The heavy metals in the sludge ash can be fixed in the structure of the cement clinker, reducing the secondary pollution to the environment;

[0026] 4) effective use of existing facilities, sludge and heat source, to achieve the purpose of sludge reduction, harmless and resource. DETAILED DESCRIPTION

[0027] The application is further described below by specific examples:

[0028] According to the "sampling gas bag method of volatile organic compounds in waste gas of fixed pollution source" (HJ 732-2014), the flue gas is collected, and according to the "determination of volatile organic compounds in waste gas of fixed pollution source by solid phase adsorption-thermal desorption / gas chromatography-mass spectrometry" (HJ732-2014), the VOCs in the flue gas are determined.

[0029] Chemical composition of sludge (%)

[0030]

[0031] Heavy metal content of sludge (mg / kg)

[0032]

[0033] Example 1

[0034] A method for efficient combustion of sludge in a combined cement kiln, the device comprises a sludge drying system, a sludge incineration system and a flue gas treatment system.

[0035] The sludge drying system: after the sludge is dewatered by a plate and frame filter press, the moisture content of the sludge is 50%; the moisture content of the dried sludge is 10%; after crushing and grinding, the fineness reaches the required 70μm.

[0036] The sludge incineration system: after the dried particles and gases are separated by a cyclone separator, they are sent into the cement kiln for incineration after being cooled by a spiral cooler; the sludge powder accounts for about 1% to 10% of the total amount of cement raw materials, and the desulfurizing agent accounts for about 0.01% of the total amount of cement raw materials.

[0037] The flue gas treatment system: the high-temperature flue gas after incineration is used as a heat source to enter the sludge drying system to dry the sludge.

[0038] The cement kiln controls the incineration temperature to be 950℃ and the time to be 20min.

[0039] The solid waste residue after incineration is used as cement clinker.

[0040] The wastewater produced in the production process contains certain pollutants, which is returned to the sludge drying system to achieve zero discharge of wastewater.

[0041] The preparation method of the desulfurizing agent:

[0042] S1: 150 kg of Mg(OH)2 is added to 1000 kg of water, 5 kg of acryloyl silane is added, stirring at 60℃ for 60 min, filtering, drying;

[0043] S2: 30 kg of DMF, 3 kg of acryloyl modified Mg(OH)2 prepared in S1 is added to the reaction kettle, stirring vigorously for 20 min, then 5 kg of organic amine is added, stirring at 60℃ for 60 min, then 0.05 kg of copper tetraaminophthalocyanine is added, continuing to react for 60 min, filtering, drying, to obtain a desulfurizer.

[0044] The organic amine is N-methylmorpholine.

[0045] The acryloyl silane is 3-(methacryloyloxy)propyl trimethoxysilane (CAS number: 2530-85-0).

[0046] Example 2

[0047] A method for efficient combustion of sludge in a cement kiln, the device comprises a sludge drying system, a sludge incineration system, and a flue gas treatment system.

[0048] The sludge drying system: after the sludge is dewatered by a plate and frame filter press, the moisture content of the sludge is 55%; after drying, the moisture content of the sludge is 15%; after crushing and grinding, the fineness reaches the required 70μm.

[0049] The sludge incineration system: after the dried particles and gas are separated by a cyclone separator, they are sent into the cement kiln for incineration after being cooled by a screw; the sludge powder accounts for about 3% of the total amount of cement raw materials, and the desulfurizer accounts for about 0.1% of the total amount of cement raw materials.

[0050] The flue gas treatment system: the high-temperature flue gas after incineration is used as a heat source to enter the sludge drying system to dry the sludge.

[0051] The cement kiln controls the incineration temperature to be 1050℃, and the time is 30 min.

[0052] The solid waste residue after incineration is used as cement clinker.

[0053] The wastewater produced during the production process contains certain pollutants, which is returned to the sludge drying system to achieve zero discharge of wastewater.

[0054] The preparation method of the desulfurizer is as follows:

[0055] S1: 160 kg of Mg(OH)2 is added to 1400 kg of water, 7 kg of acryloyl silane is added, stirring at 65℃ for 80 min, filtering, drying;

[0056] S2: 35 kg of DMF, 4 kg of acryl-modified Mg(OH)2 prepared in S1 is added to the reaction kettle, stirred vigorously, 30 min, then 7 kg of organic amine is added, temperature control 65℃ stirring 80 min, then 1 kg of tetraamino copper phthalocyanine is added, continue to react for 80 min, filter, dry, to obtain the desulfurizer.

[0057] The organic amine is N-ethyl morpholine.

[0058] The acryloxy silane is acryloxy methyl trimethoxy silane (CAS number: 21134-38-3).

[0059] Example 3

[0060] A method for efficient combustion of sludge in a cement kiln, the device comprises a sludge drying system, a sludge incineration system, and a flue gas treatment system.

[0061] The sludge drying system: after the sludge is dewatered by a plate and frame filter press, the moisture content of the sludge is 55%; after drying, the moisture content of the sludge is 20%; after crushing and grinding, the fineness reaches the required 80μm.

[0062] The sludge incineration system: after the dried particles and gas are separated by a cyclone separator, they are sent into the cement kiln for incineration after being cooled by a screw; the sludge powder accounts for about 8% of the total amount of cement raw materials, and the desulfurizer accounts for about 0.2% of the total amount of cement raw materials.

[0063] The flue gas treatment system: the high-temperature flue gas after incineration is used as a heat source to enter the sludge drying system to dry the sludge.

[0064] The cement kiln controls the incineration temperature to be 1250℃ and the time to be 40 min.

[0065] The solid waste residue after incineration is used as cement clinker.

[0066] The wastewater produced during the production process contains certain pollutants, which is returned to the sludge drying system to achieve zero discharge of wastewater.

[0067] The preparation method of the desulfurizer comprises the following steps:

[0068] S1: 190 kg of Mg(OH)2 is added to 1800 kg of water, 9 kg of acryloxy silane is added, and stirring is carried out at 75℃ for 100 min, then filtering and drying;

[0069] S2: Add 45 kg of DMF and 6 kg of acryloyl-modified Mg(OH)2 prepared in S1 into the reactor, stir vigorously for 40 minutes, then add 10 kg of organic amine, control the temperature at 65°C and stir for 100 minutes, then add 2 kg of tetraaminophthalocyanine copper, continue the reaction for 100 minutes, filter, and dry to obtain the desulfurizer.

[0070] The organic amine is N-ethylmorpholine.

[0071] The acryloxysilane is methacryloxypropyltriethoxysilane (CAS No.: 21142-29-0).

[0072] Example 4

[0073] A method for efficient combustion of sludge combined with a cement kiln. The device comprises a sludge drying system, a sludge incineration system, and a flue gas treatment system.

[0074] The sludge drying system: after the sludge is dehydrated by the plate and frame filter press, the sludge moisture content is 60%; after drying, the sludge moisture content is 35%; after crushing and grinding, the fineness reaches the required 80μm.

[0075] The sludge incineration system: the dried particles and gas are separated by a cyclone separator, and then sent to a cement kiln for incineration after spiral cooling; the amount of sludge powder added accounts for about 10% of the total amount of cement raw materials, and the amount of desulfurizer added accounts for about 0.3% of the total amount of cement raw materials.

[0076] The flue gas treatment system: the high-temperature flue gas after incineration is used as a heat source and enters the sludge drying system to dry the sludge.

[0077] The cement kiln controls the incineration temperature to be 1350° C. and the incineration time to be 45 minutes.

[0078] The solid waste residue after incineration is used as cement clinker.

[0079] The wastewater generated during the production process contains certain pollutants and is returned to the sludge drying system to achieve zero wastewater discharge.

[0080] A method for preparing the desulfurizer:

[0081] S1: Add 200 kg of Mg(OH)2 to 2000 kg of water, add 10 kg of acryloxysilane, stir and react at 80°C for 100 min, filter and dry;

[0082] S2: 50 kg of DMF, 7 kg of acryl-modified Mg(OH)2 prepared in S1 was added into a reaction kettle, and stirred vigorously for 50 min, then 12 kg of organic amine was added, and stirred at 70°C for 120 min, then 3 kg of tetraamino copper phthalocyanine was added, and reacted for 120 min, filtered, and dried to obtain the desulfurizer.

[0083] The organic amine is N,N'-dimethylpiperazine.

[0084] The acryloxy silane is (acryloxy methyl) dimethyl methoxy silane (CAS No.: 130771-16-3).

[0085] Comparative Example 1

[0086] The same as Example 3 except that no desulfurizer was added.

[0087] Comparative Example 2

[0088] The same as Example 3 except that no amino-modified Mg(OH)2 was added.

[0089] Comparative Example 3

[0090] The same as Example 3 except that no acryloxy silane was added.

[0091] The incineration rate and VOCs content in flue gas of the above examples and comparative examples were tested, and the results are shown in the following table:

[0092] Incineration rate / % VOCs content in flue gas / mg / m 3 ]] Example 1 96.15 8.2 Example 2 97.75 7.3 Example 3 99.99 5.5 Example 4 98.96 6.9 Comparative Example 1 78.34 89.5 Comparative Example 2 83.19 78.3 Comparative Example 3 85.62 71.2

Claims

1. A method for efficient combustion of sludge in a sludge cement kiln, the sludge cement kiln device being composed of a sludge drying system, a sludge incineration system, and a flue gas treatment system. The sludge incineration system: after the dried particles and gases are separated by a cyclone separator, they are sent into the cement kiln for incineration after being cooled by a spiral; the sludge powder accounts for 1-10% of the total amount of cement raw materials, and the desulfurizing agent accounts for 0.01-0.3% of the total amount of cement raw materials. The preparation method of the desulfurizing agent: S1: according to the mass fraction, 150-200 parts of Mg(OH)2 are added to 1000-2000 parts of water, 5-10 parts of acryloxy silane are added, and stirring is carried out at 60-80℃ for 60-100 min, then filtration and drying are carried out; S2: 30-50 parts of DMF and 3-7 parts of acryl-modified Mg(OH)2 prepared in S1 are added to a reaction kettle, and stirring is carried out at 60-70℃ for 60-120 min, then 5-12 parts of an organic amine are added, and stirring is carried out at 60-70℃ for 60-120 min, then 0.05-3 parts of copper tetraaminophthalocyanine are added, and the reaction is continued for 60-120 min, then filtration and drying are carried out, and the desulfurizing agent is obtained; The sludge drying system: after the sludge is dewatered by a plate and frame filter press, the moisture content of the sludge is 50-60%; after drying, the moisture content of the sludge is 10-35%; after crushing and grinding, the fineness reaches the required 70-80 μm; The flue gas treatment system: the high-temperature flue gas after incineration is used as a heat source to enter the sludge drying system to dry the sludge.

2. A method of efficient combustion of sludge in a cement kiln as claimed in claim 1 wherein: The control incineration temperature of the cement kiln is 950-1350℃, and the time is 20-45 min.

3. A method of efficient combustion of sludge in a cement kiln as claimed in claim 1 wherein: The solid waste residue after incineration is used as cement clinker.

4. A method of efficient combustion of sludge in a cement kiln as claimed in claim 1 wherein: The organic amine is selected from N-methylmorpholine, N-ethylmorpholine, and N,N'-dimethylpiperazine.

5. A method of efficient combustion of sludge in a cement kiln as claimed in claim 1, wherein: The acryloxy silane includes 3-(methacryloyloxy)propyl trimethoxysilane, acryloxy methyl trimethoxysilane, methyl methacryloyloxy propyl triethoxysilane, and (acryloxy methyl) dimethyl methoxysilane.

Images