The method that mud heat drying and sludge digestion fermentation in combining are used
Technical field:
The present invention relates to the method that a kind of mud heat drying and sludge digestion fermentation in combining are used, be to utilize the heat energy of the high-temperature steam that produces in the mummification municipal sludge process or high temperature, high humidity gas to be sludge digestion fermentation system heating technology, thereby substitute the effect of heating system in the biogas production, save the daily heat energy consumption of this system, reduce running cost.Belong to environmental protection and Pollutant Treatment technical field.
Background technology:
High speed development along with Chinese national economy, the continuous quickening of urbanization paces and the public strengthen day by day to the requirement of environmental quality, a large amount of municipal sewage plant, the whole nation builds up in succession and puts into operation, be faced with a large amount of excess sludge problem that produce every day of how handling, if these mud are dealt with improperly, will produce secondary pollution to environment.Wherein there are the pathogenic bacterium in the mud to exceed standard and the heavy metals exceeding standard problem.Therefore the dewatered sludge of sewage work any stacking of not having a suitable outlet has in recent years caused secondary pollution, and the sludge disposal problem has become the many Sewage Plant problem demanding prompt solutions of China.At present, mainly contain following several to the method for sludge treatment in the industry:
1, landfill and ocean dumping: landfill method is relative simple, adaptability is strong, but take up an area of serious, very inapplicable in thickly populated city and area, to produce potential soil pollution and groundwater pollution if the processing of rubbish seepage control technique is bad, although therefore technology is comparatively ripe, each developed country of the world adopts land-fill method to handle the ratio of mud in rapid decline, and various countries require standard more and more harsher to the landfill sludge treatment, the mud landfill can not finally avoid environmental pollution just to delay the time that environmental pollution produces, so landfill is not the best approach and the means of sludge treatment.Mud Ocean dumping meeting produces pathogenic agent breeding and frowziness, and pollution of marine environment.So many areas have begun to forbid mud ocean dumping and mud landfill disposal in Europe.
2, agricultural method: the more stable and health of this kind method, can make in the mud partial organic substances transfer soil to and change the agent composition, certain repair is played in land reclamation, but still had certain limitation.The one, degradation property is poor, water ratio height, porosity are low, needs to add a large amount of processing medicaments.Have heavy metal contamination in many sewage plant sludges, and the seepage flow of heavy metal, pathogenic agent, hardly degraded organic substance and N, P pollutes to the face of land and underground water in the mud.The 2nd, needed trucking costs is than higher.
3, sludge incineration is handled: the sludge treatment technology that with the burning is core is the treatment process of mud specialization the most completely.It can make the whole carbonizations of organism in the mud, burn pathogenic agent to death, can realize the processing of inerting completely to the mud that contains heavy metal or chemical pollutant.Can reduce pollution to greatest extent.This kind method is bigger to the treatment scale of mud, therefore is used widely at western developed country and Japan.Reach in Japan and European Union member countries' sludge incineration and to handle 60% and 20% of total amount, and the burning ash that burns the back generation can be used as and improves the soil, makes building materials etc.But investment is handled in sludge incineration and the day-to-day operation expense is higher, and the environmental protection difficulty during the simultaneity factor operation is big.
4, the mud heat drying is handled: a kind of treatment process that is the most advanced and science in the sludge treatment technology.Drying and other treatment can make mud significantly subtract appearance.Existing mud heat drying system mainly is made up of deep fat process furnace, heat exchanger and fluidized-bed.Can be kept to originally about 1/5th through the sludge volume after the drying and other treatment, product is stablized no stink, pathogen-free domestic biology.Sludge product purposes after the drying and other treatment is a lot, can be used as fertilizer, soil improvement agent, substitute energy etc.
Wherein, the drying and other treatment of mud has the following advantages:
(1) volume of mud be can reduce to greatest extent, thereby storage, disposal and trucking costs reduced.
(2) sludge product after the drying treatment both can be used as fertilizer and soil improvement agent and also can be used as fuel in other commercial processes.
(3) drying sludge can make heavy metal and the organic pollutant qualified discharge in the mud, and dry back mud is dustless, tasteless, total system operating safety, efficient, and compare its investment and running cost with sludge incineration lower.
(4) because the sludge drying device can be made closed system, the stink that evaporation is taken away can be collected, so the sludge drying treatment unit of good environmental protection can be at the local construction nearer from the Residential areas.
Because above-mentioned advantage, sludge drying is a sludge treatment method preferably, should be widely used.But owing to the 800kg water in one ton of mud need be finished drying and other treatment by heating evaporation, its processing energy consumption and energy expenditure are very high, are difficult problems of applying.
5, sludge digestion fermentative processing: the process of handling mud by the method for anaerobic digestion consumes mud and produces biogas, and a large amount of heat energy of anaeration in normal temperature digestion process process consumption is kept technological temperature, and Anaerobic Digestion mud can consume the mud total amount more than 20%.Adopt mesophilic digestion art breading mud, leavening temperature is controlled at 35 ℃, the temperature when entering fermentation system owing to mud, and be 15 ℃ winter; In Anaerobic Digestion process do not produce heat below 24 ℃ summer, must heat to total system, keeps normal technological temperature.To the bionethanation system total heat that consumes of heating approximately is its 70-80% that produces the required fuel total heat of biogas.Because it is less to produce the total amount of biogas, be difficult to realize the biogas utilization of economic worth.
To sum up, sludge drying is a kind of method of sludge treatment, at home and abroad extensively is applied, and the mud good stability of process drying and other treatment is destitute of smell; Volume and weight significantly reduces to be easy to transportation; Through the sewage sludge disinfection degree height after the pyroprocessing; Yet sludge drying and mud producing methane technology are respectively two independently technologies, are not connected each other, and the energy does not obtain repeatedly, effectively utilizes.
Summary of the invention:
Utilize mud heat drying system, in the dewatered sludge process, make moisture evaporation in the mud by the high temperature heat mud of heating, produce high-temperature steam or high humidity gas, by (special) heat exchanger to middle temperature sludge anaerobic digestion system thermal source is provided, make biogas to satisfy the normal zymotechnique temperature of this system.
The basic skills of mud heat drying is to use fuel directly or indirectly to heat mud, and the temperature of raising mud makes the moisture evaporation in the mud.Utilize the heat energy that contains in the sludge drying transpiring moisture, by heat exchanger is that sludge anaerobic digestion system is heated, and keeps the technological temperature of anaeration in normal temperature Digestive tract, makes it produce biogas, consume the mud of some amount simultaneously, reach the purpose that produces biogas and mud decrement.
The present invention is applicable to direct or indirect heating-type mud heat drying system, provides thermal source to sludge anaerobic digestion system.The biogas suggestion that Digestive tract produces is as the fuel of sludge drying system.As not adding other fuel, can satisfy the required heat of sludge anaerobic digestion system.But the dewatered sludge total amount is about 30%, and the digestion process process makes mud decrement about 20%.Promptly 50% of two co-processing mud total amounts.
The method that a kind of mud heat drying of the present invention and sludge digestion fermentation in combining are used, its technical scheme is:
Between mud heat drying system and sludge digestion fermentation system, a condensing heat exchanger is set, this condensing heat exchanger is divided into temperature end and low-temperature end, and temperature end links to each other with mud heat drying system, and low-temperature end links to each other with the sludge digestion fermentation system.
High-temperature steam that mud heat drying system produces in the process of carrying out the mud heat drying or high humidity gas, the temperature end heat exchange that enters condensing heat exchanger, gas temperature is reduced to 40~50 ℃, the formation water of condensation that is condensed of the moisture in the gas; Simultaneously, the Digestive tract liquid of condensing heat exchanger low-temperature end is heated, and Heating temperature is more than 35 ℃, and is delivered to and its sludge digestion fermentation system that connects, as the required heat of sludge digestion fermenting process.
Wherein, described sludge digestion fermentation system links to each other with mud heat drying system by pipeline, and the biogas that the sludge digestion fermentation system is produced inputs in the mud heat drying system, as the fuel of heating mud.
Wherein, described condensing heat exchanger can be one or more concurrent working.
Wherein, the water coolant of described condensing heat exchanger low-temperature end also can be clean water.
Wherein, when the art of this patent is used for non-air medium circulation sludge drying system, when being non-similar fluidized bed drying system, owing to what come out from dehumidification system is to contain the mud steam that the equipment poor sealing causes the air that bleeds on a small quantity, this dehumidification system mud vapour outlet is connected with the hot side inlet of condensing heat exchanger, induced draft fan is installed in the outlet in condensing heat exchanger hot junction, make condensing heat exchanger inside be in micro-vacuum state, the process furnace that the induced draft fan expellant gas is sent to dehumidification system participates in air-breathing and eliminates stink.
The method that a kind of mud heat drying of the present invention and sludge digestion fermentation in combining are used, its advantage and effect be can with two of mud heat drying and mud producing methane (sludge digestion fermentation) technologies independently technology carry out effective combined utilization, make to form each other and be connected, thereby make the energy obtain repeatedly, effectively utilize, help save energy.
Description of drawings:
Figure 1 shows that the schema of technology of the present invention.
Embodiment:
Below in conjunction with specific embodiment, technical scheme of the present invention is described further.
Mud heat drying system mainly is made up of deep fat process furnace, heat exchanger and fluidized-bed; The sludge digestion fermentation system mainly is made of the biogas jar, between mud heat drying system and sludge digestion fermentation system, a condensing heat exchanger is set, this condensing heat exchanger is divided into temperature end and low-temperature end, this condensing heat exchanger is provided with a pair of air inlet/outlet, links to each other with the fluidized-bed air inlet/outlet; One Digestive tract liquid-inlet; One Digestive tract liquid exit links to each other with the biogas jar;
Wherein, if described mud heat drying system is by deep fat process furnace, heat exchanger and un-fluidized-bed dehumidification system, condensing heat exchanger hot junction venting port links to each other with the deep fat process furnace.
When the art of this patent is used for non-air medium circulation sludge drying system, when being non-similar fluidized bed drying system, owing to what come out from dehumidification system is to contain the mud steam that the equipment poor sealing causes the air that bleeds on a small quantity, this dehumidification system mud vapour outlet is connected with the hot side inlet of condensing heat exchanger, induced draft fan is installed in the outlet in condensing heat exchanger hot junction, make condensing heat exchanger inside be in micro-vacuum state, the process furnace that the induced draft fan expellant gas is sent to dehumidification system participates in air-breathing and eliminates stink.
The mud of will doing, wet carries out batch mixing in 1: 1 ratio of mass ratio in mixer, wherein the water ratio of dewatered sludge is less than 10%, and the water ratio of wet mud is 80%.Through the mud knife mill mud that mixes is shredded in the fluid bed dryer of going forward side by side.The water ratio of chopping mud is below 45%.
The deep fat process furnace uses biogas and/or Sweet natural gas to act as a fuel, the deep fat process furnace is heated to deep fat about 250 ℃ and delivers to heat exchanger, deep fat and dry gas carry out thermal energy exchange, the temperature of dry gas is raise, go forward side by side into the bottom of fluidized-bed, mud on the fluidized-bed is carried out mummification, and this dry gas is taken away the moisture in the mud after by mud, thereby humidity greatly increases and forms high humidity gas; The hot junction heat exchange that this high humidity gas enters condensed heat exchanger through the inlet mouth of condensing heat exchanger, gas temperature are reduced to 40~50 ℃, the formation water of condensation that is condensed of the moisture in the gas; Simultaneously, the Digestive tract liquid of condensing heat exchanger low-temperature end is heated, and Heating temperature is more than 35 ℃, and is delivered to and its biogas jar that connects, as the required heat of sludge digestion fermenting process.
Wherein, needing the Digestive tract liquid of heating is two portions, promptly newly enters the liquid of Digestive tract and the liquid that Digestive tract is fermenting.Purpose is to keep the normal design technological temperature of system.
Wherein, described condensing heat exchanger can be provided with a venting port, and this venting port links to each other with the deep fat process furnace of mud heat drying fermentation system, so that expellant gas participates in burning, heating mud as the part of combustion air.
Wherein, the exhaust ports of described condensed heat exchanger also is provided with an air exhauster, be in negative pressure state when keeping its work, the gas that mud heat drying system is produced attracted to gas after condensed heat exchanger and the heat exchange and is sent back to mud heat drying system and participate in burning.
Wherein, the biogas jar links to each other by the deep fat process furnace of pipeline with mud heat drying system, and the biogas that the sludge digestion fermentation system is produced inputs in the deep fat process furnace, as the fuel of heating mud.
Wherein, described condensing heat exchanger can be one or more concurrent working.
Wherein, the water coolant of described condensing heat exchanger low-temperature end also can be clean water.