KR20160117892A - Sludge-dry method by application of carbon powder - Google Patents

Abstract

Sewage sludge, livestock manure, food waste, and organic sludge from various industries suffer from difficulty in their treatment due to their high moisture content despite their own sufficient calorie and availability in terms of nutritional factors and calorific value. In the process of drying (burning) water more effectively, the drying efficiency and fuel cost problems due to flocculation of the sludge and the difficulty of operating the facility due to seizure on facilities are experienced. Therefore, when the fine carbon powder is preheated to a high temperature and mixed with the sludge, sludge is agglomerated into a lump with sludge being powdered, and the sludge (or sludge) is basically prevented from sticking to surrounding facilities. At the same time, when additional hot air heating (external indirect heating is also possible), the carbonaceous material with good thermal conductivity maintains a certain temperature and sufficiently mixed sludge and carbide share the moisture of the sludge, have. In addition, when the dried material is introduced into the microwave in the state where the air is blocked and dried and (partial) carbonization is carried out, it is possible to make eco-friendly fuel which reduces the emission of harmful gas in the combustion process while maintaining the heat value of the dried material. All or some of the sludge dried material can be used as a sludge drying fuel.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of drying a sludge containing high-

The present invention is a technology for drying / carbonizing sewage sludge, livestock manure, food waste and various industrial sludge using more effective and less energy.

(Kim, Seung Hyun, Dept. of Ph.D., Yeungnam University, 2012) A Study on the Characteristics of Dyeing and Sewage Sludge According to the Conditions of Operation of Multi-Stage Net Hot Air Dryer as a Technology Designed with Background of Fine Pulverized Carbide and Microwave and High Efficiency Dryer (10-2011-0124151) filed by the applicant (Hansang-dong), it is possible to achieve the drying purpose for a shorter period of time by microwave if necessary. The sludge (or sludge) dried to conform to the recently revised regulations on the use of solid fuels may be used as fuel through powder or molding.

The dewatering cake of the sewage treatment plant or animal manure contains a polymeric coagulant used to increase cohesiveness, and most of the sludge contains not only a large amount of water in the fine cell tissue, but also moisture When the heat is applied from the outside, it acts as a heat shield or a kind of thermal barrier coating itself. Therefore, when the heating is continuously performed at a high temperature, the heat applied part is burned and they are bundled together, thereby blocking evaporation and divergence of the inside, interfering with heat transfer, and drastically lowering the drying efficiency. Furthermore, if the combustible material with the surface of the rust adhered to the wall, it becomes clogged like charcoal, which makes maintenance of the facility difficult. The present invention basically prevents such coagulation and solidification of the sludge as well as the sludge burnt on the wall surface against heating from the outside, and more effectively, the fine carbonized (carbon) particles mixed together absorb the moisture of the sludge Thereby improving drying efficiency.

For this purpose, the present invention uses fine carbide powder. Using carbonized powders heated at high temperature in advance, the average moisture content of the mixed mixture is adjusted to be not more than 40% at a constant ratio (1: 1 to 3: 7) to the target sludge, The sludge absorbs the moisture leaking out of the sludge and the sludge that has lost its moisture will lose its binding force, so that the amount of carbon They are ideally mixed to form a powder having a constant water content as a whole. In order to sufficiently utilize the supplied external heat source and to filter the harmful components contained in the exhaust gas, when the exhaust gas is forcedly flowed into the portion filled with the fine powder carbide and the mixture is forcedly mixed (using a stirrer or an impeller) This low-thermal-conductivity carbide powder has a relatively high temperature as compared with the surrounding sludge, and the heating / mixing phenomenon is accelerated so that the mixture of the sludge and the carbonized powder is thoroughly mixed and becomes very fine particles. As heating is continued and the mixing of the sludge and the carbonized powder proceeds, if the amount of heat exceeding the latent heat of evaporation of the water is applied, the moisture is evaporated at a high rate through the wide gap of carbon.

When this principle is applied to an actual heat drying furnace (hot air drying, indirect heating, or sludge incinerator), it is necessary to reduce the energy required for drying, as well as heat loss due to sludge burning on the wall of the drying furnace , And it can reduce the time and financial loss due to the maintenance of the facility. At the same time, when a certain level of flame retardant material is used for the carbide to be used, it is possible to selectively reuse the carbide, thereby minimizing the loss. Also, according to the experimental results, the drying efficiency is drastically lowered at about 30% of the moisture content as the drying progresses. At this time, the mixture of the sludge and the carbonized powder is subjected to secondary drying (carbonization is possible) The desired drying / carbonization state can be effectively achieved by the internal heating principle of the microwave.

Representative chart: Flow chart of drying / carbonizing process using carbide (dry) powder: As a whole process arrangement and process flow chart for drying sludge or food waste, dry powder (plant or fossil fuel) is heated at high temperature using microwave . The sludge and carbide mixture maintains an average moisture content of less than 40% depending on the mixing ratio, which is very advantageous in terms of transportation and drying effect. The dried sludge is used as a solid fuel (or a desired recycled material), and the carbide is subjected to a drying process using a indirect heating and drying furnace to remove residual water and volatile Minute, and after heating at a high temperature (400 to 1,800 ° C), mix with sludge again. At this time, when sludge or food wastes are also required to be carbonized, the sludge-carbonized mixture dried in the drying furnace can be carbonized using a microwave.
Drawing 1 - High efficiency drying device by indirect heating Assembly / Outline drawing: The drying device is composed of a stove that burns fuel, a jacket surrounding the stove, a sieve filled in the jacket, and a rotating part that stirs the mixture of carbonized powder. . The stove is a cylindrical type, which is similar to a general solid fuel stove as a device for injecting and burning solid fuel therein. However, there is no separate stack, and the flue gas flowing into the jacket through the fine holes drilled in the lower part of the hearth and the harmful gas is filtered through the mixture of the sludge and the carbonized powder filled in the jacket, . The outer jacket surrounding the cylindrical hearth has a closed structure. The mixture (sludge and carbonized powder) is introduced into the jacket through the upper hopper, and the mixture (sludge and carbonized powder) is spirally wound around the stove through the rotary type stirrer Through the bottom outlet. The rotary type stirrer installed to rotate around the hearth is rotated by a separate external power and is rotated to forcibly rotate the mixture in the jacket so as to be spirally wound around the hearth to be discharged. The spiral wing structure Four to six stirrers are installed to increase the stirring effect of the mixture.
Drawing 2 - High-Efficiency Drying Device by Indirect Heating Each component diagram: The drying device is mainly composed of a fireplace, a jacket, and a rotating body, and is a drawing of each major part constituting the three parts.
Drawing-3 - High-Efficiency Drying Device by Indirect Heating Assembly of Rotor Assembly: Assembly of a device that stirs the mixture (mixture of sludge and carbide) filled between the hearth and jacket by using the rotational force from the outside of the drying device FIG.
Drawing-4: Each part constituting the rotating body.

In order to carry out the invention, preliminary experiments have been carried out through small-scale household microwaves since 2007, and since October 2011, 12-kilowatt microwave facilities and auxiliary facilities have been installed in the Boeun sewage treatment plant in Chungcheongbuk- , Sludge, and the optimization of the process composition. As a result, the following items were included in the process. First, fossil solid fuels or wood-based materials are carburized and carbonized (fossil solid fuels and wood-based materials may be blended at a certain ratio) and then flame retarded. It is made into fine powder (or food waste). At this time, the finer the sludge is, the better the drying effect is, and the higher the temperature of the pre-flame-treated carbide is, the better. When this is dried through a high-efficiency indirect heater, a good heat-conductive carbide absorbs and evaporates moisture from the agglomerated sludge, thereby enhancing the drying effect. At this time, stirring at a constant speed to allow the evaporated water to escape well can be more effective. In addition, in order to effectively dry / remove the moisture and volatile substances absorbed in the powdery carbide during the forced mixing process with the sludge, the carbide is effectively introduced into the microwave of the closed structure to effectively dry it from the inside, And the mixing efficiency with the sludge is increased by heating at a high temperature. In this case, when the dried sludge is mixed with the carbide without being sorted and separated, the sludge can be carbonized, and the carbonized gas generated in the carbonization process can be supplied to the dryer to be used as a heat source.

Claims (1)

High-efficiency indirect drying equipment (with drawing) to increase thermal efficiency in drying process of flame-retarded coated carbide (carbon) and sludge

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