Two-phase heat exchanger and system utilizing cement kiln waste heat to dry sludge

Abstract

The invention discloses a two-phase heat exchanger and a system utilizing cement kiln waste heat to dry sludge and comprises a garbage disposal cement kiln smoke discharge pipeline and a sludge drier, wherein the sludge drier is provided with a drying box section passing through the sludge, a hot air feeding pipeline is communicated with the drying box section, a sealed two-phase heat exchanger is arranged between the smoke discharge pipeline and the hot air feeding pipeline; a condensation section of the heat exchanger is arranged in a hot air feeding pipe, an evaporation section of the heatexchanger is arranged in the smoke discharge pipeline. In the heat exchanger and the system, a device is sealed, wherein heat quantity in the device is transferred by two-phase heat transfer dependedon phase state change of the fluid enclosed in the device, and the thermal efficiency is over 95%; 30% thermal energy can be recycled, therefore, comprehensive thermal efficiency is higher. The system can avoid bad smell from two aspects: 1, desiccation temperature of the sludge is lower, so that overflow of volatile matter is small; the air used for desiccating the sludge is the sealed self-circulation air, a little air is released when the system is decompressed and adjusted, and the air is burnt out through a simple deodorization device or direct introduction to the cement kiln, and influence to the external environment is avoided.

Description

technical field [0001] The invention relates to the field of sludge treatment and disposal, in particular to a two-phase heat exchanger and a system for drying sludge by utilizing waste heat of a cement kiln. Background technique [0002] The treatment and disposal of urban sewage sludge is accompanied by the generation of sewage treatment plants. Sludge is the largest by-product produced in the process of urban sewage treatment. It has a high moisture content and is not easy to dehydrate. Sludge contains not only perishable organic substances and inorganic nutrients, but also a large number of pathogenic bacteria, parasites (eggs), heavy metals such as Cu, Zn, Cr and Hg, and some harmful refractory organic substances, such as polycyclic aromatic hydrocarbons, etc. These chemicals not only contaminate surface water and groundwater sources, but also pollute the air with odor from sludge, and pathogens are a potential threat to human health. In the past, our country has alw...

AI Technical Summary

Problems solved by technology

The water content of dewatered sludge is high, generally 75-85%. If the dewatered sludge is directly used in the above-mentioned treatment and disposal process, there are many problems: 1) The high water content of wet sludge leads to low calorific value of sludge and reduced utilization value ; 2) The characteristics of the sludge itself make it difficult to dry, high energy consumption, and increase the cost of utilization; 3) The sludge is highly viscous, and it is easy to stick to the wall of the device, blocking and corroding the equipment; 4) The state of the wet sludge is unstable It is easy to generate biogas during storage, as well as dust and volatile combustibles during production, which bring safety hazards such as spontaneous combustion and explosion.

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