CN102730934B - Method for pretreating sludge before hot drying - Google Patents
Method for pretreating sludge before hot drying Download PDFInfo
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- CN102730934B CN102730934B CN201210252490.5A CN201210252490A CN102730934B CN 102730934 B CN102730934 B CN 102730934B CN 201210252490 A CN201210252490 A CN 201210252490A CN 102730934 B CN102730934 B CN 102730934B
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Abstract
The invention discloses a method for pretreating sludge before hot drying. The method comprises the following steps: before hot-drying by using hot-drying equipment, feeding powdery slaked lime in dewatered sludge with water content of 75-85%, and evenly mixing, wherein the mass ratio of the slaked lime and the dry sludge solid is 3-4%, therefore, sludge bonding in the hot drying process is avoided.
Description
Technical field
The invention belongs to solid waste disposal, disposal technology field, be specifically related to the pretreatment process before a kind of sludge hot drying.
Background technology
Along with China's level of urbanization improves constantly, sewage treatment facility high speed development, sewage load and processing rate are all in steady increase.But the excess sludge as sewage disposal by product is also rolling up.In water ratio 80%, annual dewatered sludge (referring to that the water ratio that excess sludge is formed after preliminary hydro-extraction is the mud of the 75-85%) output in the whole nation has reached 30,000,000 tons.A large amount of mud, if do not dealt carefully with disposal, will cause serious harm to environment.Conventional specific resistance to filtration method comprises landfill, burning, compost and building materials and utilizes, but the mud of 80% water ratio is difficult to directly carry out above-mentioned process disposal, must reduce moisture percentage in sewage sludge further.Sludge hot drying is the main means realizing the reduction of dewatered sludge water ratio, and its processing efficiency, energy consumption and environmental safety have influence on the operation of whole specific resistance to filtration system.Whether contact with mud according to medium, Technology of Thermal Drying can be divided into direct heated drying and Indirect thermal drying.Direct heated drying is dry also known as convection heat, and be remove moisture by warm air from Sludge Surface, relevant device is as rotary drum drier, conveyor dryer and fluid bed dryer etc.; Indirect thermal drying also known as conductive drying, thermal medium by wall by heat trnasfer to mud, to make in mud moisture evaporation, the equipment of representative has video disc drying machine, paddle drying machine etc.
No matter be direct hot drying equipment or Indirect thermal drying equipment, all face the common issue of mud bonding aborning.In drying process, when moisture percentage in sewage sludge is down to 50 ~ 60%, viscosity increases rapidly, and the situation that mud is bonded in drying plant inwall often occurs, and mud agglomerate now often surface drying and inner thickness.Mud bonding phenomenon can reduce the heat transfer efficiencies of drying plant, hinders the evaporation of moisture in mud, thus reduces rate of drying, causes energy wastage, increases processing cost.Meanwhile, mud bonding also may affect the work-ing life of sludge drier, and the over-drying risk of explosion that also can increase drying plant of bonding mud, causes security threat.
In order to solve the dry adhesion problem of sludge hot, usually the method for dry mud back-mixing is adopted in practice, dry mud back-mixing is the dewatered sludge (water ratio is generally below 30%) of admixture drying in the pending mud of 80% water ratio, mixing sludge water ratio is made to be reduced to less than 50%, stride across the bonding stage of mud, and then carry out drying.The main deficiency of the method is that back-mixing mud addition content is very large, and cause device processes ability to reduce, reheating of back-mixing mud can cause energy wastage.Some hot drying equipments devise the mechanical components such as scraper plate at device interior, or by the adjustment to device interior stirring, structure for conveying, produce the effect removing part adhesive mud.This mode also can increase manufacture and the maintenance cost of equipment, and can not avoid mud adhesion problem completely.Unslaked lime also can be used for sludge-drying, it is the principle utilizing unslaked lime and water effect to generate white lime heat release, suitable reduction moisture percentage in sewage sludge, improve sludge character, the mass ratio of this method unslaked lime and mud is generally 20 ~ 30%, but mud also needs further drying, and mud adhesion problem can not be avoided completely.
Summary of the invention
Technical problem to be solved by this invention is: make up above-mentioned the deficiencies in the prior art, proposes the pretreatment process before a kind of sludge hot drying, can avoid the bonding of mud in heated drying process, improves drying sludge speed.
Technical problem of the present invention is solved by following technical scheme:
Pretreatment process before a kind of sludge hot drying, comprise the steps: before carrying out drying with hot drying equipment, be add powder white lime in the dewatered sludge of 75 ~ 85% at water ratio, and be uniformly mixed, wherein, the mass ratio of white lime and sludge dry solids is 3 ~ 4%, thus reduces the bonding of mud in heated drying process.
Due in heated drying process, mud bonding is mainly because the viscous substances such as protein, polysaccharide and polymeric flocculant in mud are under amount of water condition, stick to that moisture eliminator wall surface causes, therefore, avoid bonding, need to reduce these viscous substance quantity and the contact with dry wall thereof.Contriver finds through large quantifier elimination, before carrying out heated drying, by adding a small amount of white lime and make it and mud mixing and stirring in mud, the bonding of mud in heated drying process can be avoided, trace it to its cause, contriver thinks on the one hand, under sludge hot drying conditions, Sludge Surface viscous substance can be degraded under alkali heat effect, on the other hand, white lime and mud mineral can react generation Wingdale, Calucium Silicate powder, the inorganic minerals such as calcium aluminate, thus improve the viscosity of mud, the contact of relative minimizing viscous substance and dry wall, thus reduce the bonding amount of mud.
Preferably, in described dewatered sludge, also add flyash, the mass ratio of described flyash and sludge dry solids is 1-3%.
Flyash is the primary solids refuse that coal-burning power plant discharges, and the main oxides of power plants flyash consists of SiO
2, Al
2o
3, FeO, Fe
2o
3, CaO, TiO
2deng, flyash is one of industrial residue that the current discharge capacity of China is larger, and along with the development of power industry, the flyash quantity discharged of coal-burning power plant increases year by year.A large amount of flyash does not add process, will produce airborne dust, atmosphere pollution; River can be caused to silt up if enter water system, and toxic chemical substance wherein also can work the mischief to human body and biology.The amendment that flyash also can dewater as mud (referring to the mud of the water ratio 96 ~ 99% that Sewage Plant is discharged), its adding proportion is generally 15 ~ 20% of sludge dry solids quality, its advantage to realize utilization of waste material, shortcoming is that sludge dry solids increase is more, affect mud decrement, sludge calorific value reduces simultaneously, and the boiler abrasion of follow-up burning disposal can be increased the weight of, and the present invention utilizes white lime and flyash to carry out pre-treatment to mud in the lump, white lime and the total consumption of flyash only account for the 4-7% of the solid body of lignin-sludge, in water ratio 80%, only account for 0.8 ~ 1.4% of dewatered sludge gross weight, surprising discovery, the adhesion problem of mud obtains and solves thoroughly, and the drying rate of mud is also improved to some extent.
Preferably, stirring intensity is 60-80rpm, and churning time is 3-5min.
Under stirring intensity in above technical scheme and churning time, the white lime added can't cause liquefaction phenomenon and the contact metamorphism of mud, can reduce mud bonding amount during follow-up heated drying process further.
Preferably, described in be uniformly mixed be carry out in sludge screw conveyer before hot drying equipment, white lime or white lime and flyash add in the front end of sludge screw conveyer.
The further tool of the present invention has the following advantages: 1, the consumption of white lime or itself and flyash is few, and cost is low; 2, without the need to newly added equipment, the problem of mud bonding can thoroughly be solved; 3, white lime and flyash are as inorganic conditioner, and addition is little, have no adverse effects to dewatered sludge subsequent disposal; 4, present method technique is simple, and which kind of drying plant no matter mud after treatment use carry out drying, all has unusual effect.
Accompanying drawing explanation
Fig. 1 be mud A in the embodiment of the present invention one without pre-treatment and in mud A Ca (OH)
2when dosage is respectively 1%, 3%, 4% of the solid body of mud A, in heated drying process, the bonding amount of mud compares schematic diagram;
Fig. 2 be mud A in the embodiment of the present invention one without pre-treatment and in mud A Ca (OH)
2when dosage is respectively 1%, 3%, 4% of the solid body of mud A, in heated drying process, the drying sludge time compares schematic diagram;
Fig. 3 is that mud in the embodiment of the present invention two is without pre-treatment and the Ca (OH) adding sludge dry solids 3% in mud
2during flyash with sludge dry solids 2%, in heated drying process, the bonding amount of mud compares schematic diagram;
Fig. 4 be in the embodiment of the present invention two mud not without pre-treatment and the Ca (OH) adding sludge dry solids 3% in mud
2during flyash with sludge dry solids 2%, the drying sludge time compares schematic diagram.
Embodiment
Contrast accompanying drawing below and in conjunction with preferred embodiment, the present invention be explained in detail.
The invention provides the pretreatment process before a kind of sludge hot drying, in a kind of embodiment, comprise the steps: before carrying out drying with hot drying equipment, be add powder white lime in the dewatered sludge of 75 ~ 85% at water ratio, and be uniformly mixed, wherein, the mass ratio of white lime and sludge dry solids is 3 ~ 4%, thus avoids the bonding of mud in heated drying process.Preferably, in described dewatered sludge, also add flyash, the mass ratio of described flyash and sludge dry solids is 1-3%.Preferred stirring intensity is 60-80rpm, and churning time is 3-5min.Preferably further to be uniformly mixed in sludge screw conveyer.
Wherein, water ratio refers to the percentage ratio of the weight of contained humidity in mud and the ratio of mud gross weight.
Pretreatment process of the present invention is applicable to the dewatered sludge of various mud (by product excess sludge and thickened sludge, digested sludge etc. as sewage disposal), but particularly remarkable to the dewatered sludge effect of organic sludge.
Below to process the dewatered sludge of organic sludge, by preferred embodiment, the present invention is described in detail.
Embodiment one
Certain urban wastewater treatment firm produces dewatered sludge (hereinafter referred to as mud A), its water ratio is 75%, organic content is 52%, in mud A, the white lime relative to sludge dry solids quality 3% is added in the front end of sludge screw conveyer, in sludge screw conveyer course of conveying, stir 5min, stirring intensity is 60rpm.Mud after pre-treatment enters tumble dryer, convection drying under 120 DEG C of conditions, and drying machine inwall does not almost bond mud.And under similarity condition, not during pretreated drying sludge, drying machine inwall can be seen obvious mud adheres to.
Under same treatment condition, as shown in Figure 1, for the present embodiment mud A without pre-treatment and in mud A Ca (OH)
2when dosage is respectively 1%, 3%, 4% of the solid body of mud A, the comparison schematic diagram of mud bonding amount in heated drying process, can find out after white lime conditioning, the bonding amount of mud significantly reduces, substantially can ignore, white lime dosage be 1% mud in follow-up drying, have a large amount of bonding, the bonding amount not adding the mud of white lime is maximum; Fig. 2 be the present embodiment mud A without pre-treatment and in mud A Ca (OH)
2when dosage is respectively 1%, 3%, 4% of the solid body of mud A, in heated drying process, the time of drying of mud compares schematic diagram, can find out that the drying sludge time significantly shortens after white lime conditioning.
Embodiment two
Certain urban wastewater treatment firm produces dewatered sludge, and its water ratio is 75%, and organic content is 52%.In mud, add the flyash of white lime relative to sludge dry solids quality 3% and 2% in the front end of sludge screw conveyer, with mud mixing 5min in worm conveyor, stirring intensity is 60rpm.Mud after pre-treatment enters tumble dryer, convection drying under 120 DEG C of conditions, and drying machine inwall does not almost bond mud.And under similarity condition, not during pretreated drying sludge, drying machine inwall can be seen obvious mud adheres to.
Under same treatment condition, as shown in Figure 3, the mud of the present embodiment is without pre-treatment and the Ca (OH) adding sludge dry solids 3% in mud
2after the flyash of sludge dry solids 2%, in heated drying process, the bonding amount of mud compares schematic diagram, and after can finding out conditioning, mud bonding amount significantly reduces, and substantially can ignore; As shown in Figure 2, the present embodiment mud without pre-treatment and add in mud sludge dry solids 3% Ca (OH)
2during flyash with 2% of sludge dry solids, the drying sludge time compares schematic diagram, and after can seeing conditioning, the drying sludge time significantly shortens.
Embodiment three
Certain urban wastewater treatment firm produces dewatered sludge, and its water ratio is 75%, and organic content is 52%.In mud, add the flyash of white lime relative to sludge dry solids quality 4% and 1% in the front end of sludge screw conveyer, with mud mixing 5min in worm conveyor, stirring intensity is 60rpm.Mud after pre-treatment enters tumble dryer, convection drying under 120 DEG C of conditions, and drying machine inwall does not almost bond mud.And under similarity condition, not during pretreated drying sludge, drying machine inwall can be seen obvious mud adheres to.
Embodiment four
Certain urban wastewater treatment firm produces dewatered sludge, and its water ratio is 81%, and organic content is 67%.In mud, add the flyash of white lime relative to sludge dry solids quality 4% and 3% in the front end of sludge screw conveyer, with mud mixing 3min in worm conveyor, stirring intensity is 80rpm.Mud after pre-treatment enters tumble dryer, convection drying under 120 DEG C of conditions, and drying machine inwall does not almost bond mud.And under similarity condition, not during pretreated drying sludge, drying machine inwall can be seen obvious mud adheres to.
Above content is in conjunction with concrete preferred implementation further description made for the present invention, can not assert that specific embodiment of the invention is confined to these explanations.For general technical staff of the technical field of the invention, without departing from the inventive concept of the premise, make some equivalent to substitute or obvious modification, and performance or purposes identical, all should be considered as belonging to protection scope of the present invention.
Claims (3)
1. the pretreatment process before a sludge hot drying, it is characterized in that comprising the steps: before carrying out drying with hot drying equipment, be add powder white lime in the dewatered sludge of 75 ~ 85% at water ratio, and be uniformly mixed, wherein, stirring intensity is 60-80rpm, churning time is 3-5min, the mass ratio of white lime and sludge dry solids is 3 ~ 4%, Sludge Surface viscous substance is degraded under alkali heat effect, simultaneously, white lime and mud mineral are reacted and are generated Wingdale, Calucium Silicate powder, calcium aluminate inorganic mineral, improve the viscosity of mud, the contact of relative minimizing viscous substance and dry wall, thus reduce the bonding amount of mud, avoid the bonding of mud in heated drying process.
2. the pretreatment process before sludge hot drying as claimed in claim 1, it is characterized in that: in described dewatered sludge, also add flyash, the mass ratio of described flyash and sludge dry solids is 1-3%.
3. the pretreatment process before sludge hot drying as claimed in claim 1 or 2, it is characterized in that: described in be uniformly mixed be carry out in sludge screw conveyer before hot drying equipment, white lime or white lime and flyash add in the front end of sludge screw conveyer.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210252490.5A CN102730934B (en) | 2012-07-20 | 2012-07-20 | Method for pretreating sludge before hot drying |
| HK12112581.6A HK1171731A1 (en) | 2012-07-20 | 2012-12-05 | Pre-processing method of sludge before being thermal dried |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210252490.5A CN102730934B (en) | 2012-07-20 | 2012-07-20 | Method for pretreating sludge before hot drying |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN102730934A CN102730934A (en) | 2012-10-17 |
| CN102730934B true CN102730934B (en) | 2015-04-01 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201210252490.5A Active CN102730934B (en) | 2012-07-20 | 2012-07-20 | Method for pretreating sludge before hot drying |
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| CN (1) | CN102730934B (en) |
| HK (1) | HK1171731A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104609697A (en) * | 2015-02-28 | 2015-05-13 | 西安市利生污泥处理有限公司 | Composite sludge gel breaker as well as preparation and application thereof |
| CN110372396B (en) * | 2019-08-05 | 2022-02-08 | 武汉钢铁有限公司 | Integrated process method for sludge dewatering and ceramsite firing preparation of comprehensive wastewater of iron and steel plant |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101500952A (en) * | 2006-08-08 | 2009-08-05 | 底格里蒙公司 | Method and installation for packaging muds before drying |
| CN101514072A (en) * | 2009-02-26 | 2009-08-26 | 北京四方如钢混凝土制品有限公司 | Mud granulizing method, mud granule produced thereby and application thereof |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102303944B (en) * | 2011-08-22 | 2014-08-27 | 广州新致晟环保科技机械设备有限公司 | Method for re-treating dewatered sludge |
-
2012
- 2012-07-20 CN CN201210252490.5A patent/CN102730934B/en active Active
- 2012-12-05 HK HK12112581.6A patent/HK1171731A1/en not_active IP Right Cessation
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101500952A (en) * | 2006-08-08 | 2009-08-05 | 底格里蒙公司 | Method and installation for packaging muds before drying |
| CN101514072A (en) * | 2009-02-26 | 2009-08-26 | 北京四方如钢混凝土制品有限公司 | Mud granulizing method, mud granule produced thereby and application thereof |
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| Publication number | Publication date |
|---|---|
| HK1171731A1 (en) | 2013-04-05 |
| CN102730934A (en) | 2012-10-17 |
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