waste disposal unit

Plate and frame filter press is an intermittent solid-liquid separation equipment, which is composed of filter plates and filter frames arranged to form filter chambers. Under the action of the feeding pump, the feed liquid is sent into each filter chamber, and the solid and liquid are separated through the filtering medium. Widely used in industries such as sewage treatment. It has the advantages of good separation effect, wide applicability, simple operation, and low investment, especially for the separation of viscous fine materials, which has incomparable superiority.

Technical principles

Based on independent research and development, Zhengzhou Xindi has developed a process for harmless treatment and comprehensive utilization of sludge through system integration and optimized coupling. The low-temperature sludge drying device and the oxygen deficient medium temperature pyrolysis unit are the core units. Among them, the oxygen deficient medium temperature pyrolysis technology of sludge is different from other oxidation and pyrolysis technologies. The key point is that sludge pyrolysis produces combustible gases and charcoal from sludge under thermal conditions that isolate oxygen or have little oxygen. The process of producing combustible gases in the thermal cracking unit of sludge is only the cracking reaction part in traditional gasifiers, and the carbon in the sludge basically does not participate in the reaction, as long as it can provide a cracking reaction temperature of 300-600 ℃. The reaction mechanism is that the organic macromolecule chains in the sludge are broken into multiple small molecules by heat, and the chemical bond energies originally contained in them are redistributed to various small molecules. These small molecules are classified according to their physical and chemical properties to obtain what people call "gas, carbon" substances.
The main reactions are as follows:
C+CO2 ↔ 2CO

C+H2O ↔ CO+H2

C+2H2 ↔ CH4

CO+H2O ↔ CO2+H2

CH4+H2O ↔ CO+3H2

During the reaction process, due to anaerobic distillation, it will not produce dioxins like incineration; All organic matter in the sludge is converted into high value-added products, and inorganic matter is completely reduced to become stable slag, which is discharged from the bottom of the reactor through a specially designed slag removal mechanism. The main components of these slag are active substances such as dicalcium silicate and tricalcium silicate. If the heavy metal content meets the standard, it can be directly added to the raw materials for brick making and used as building materials. It can also be directly buried. If the heavy metal content is high, it can be directly removed or solidified and sealed to achieve complete harmlessness.

Household waste belongs to biomass waste, and the volatile matter in household waste is particularly high, accounting for about 70% of the calorific value, while coal is relatively low, with anthracite accounting for less than 10%. Volatile matter is mainly composed of high calorific value hydrogen, oxygen, methane, and hydrocarbons. Coal mainly generates heat during combustion, while household waste releases a large amount of volatile matter at 225-500 ℃ during combustion. It is difficult to completely burn it with a single gas supply, so household waste is not suitable for direct combustion. The way to burn household waste is to use medium temperature and oxygen deficient pyrolysis to extract the volatile components from the waste and convert them into biomass combustible gas, which can be burned like natural gas. That is to say, household waste is a good raw material for producing combustible gases.

Compared with traditional pyrolysis of household waste, thermal cracking with low temperature and oxygen in household waste can produce combustible gases, but there is a qualitative difference.

Traditional household waste pyrolysis

Traditional household waste pyrolysis is high-temperature pyrolysis, which produces combustible gases and ash from waste under thermal conditions of partial carbon combustion and partial carbon reduction.

The traditional pyrolysis of household waste produces combustible gases mainly through the oxidation-reduction and cracking reactions of the waste raw materials. Oxidation reaction: It is a combustion reaction between a portion of carbon in garbage and air, generating a large amount of carbon dioxide and releasing heat at a temperature of up to 1000-1300 ℃. This heat provides a heat source for reduction and cracking reactions.

Reduction reaction: Carbon dioxide and residual carbon generated in the oxide layer undergo a reduction reaction with water vapor, producing carbon monoxide and hydrogen gas.

Cracking reaction: At a temperature of 225-500 ℃, combustible gases, carbon, tar, and water vapor are released.

The combustible gases produced by traditional household waste pyrolysis are carbon monoxide (15-20%), nitrogen (about 50%), and volatile gases (only 30-35%), so their calorific value is relatively low. The calorific value of combustible gas per cubic meter of waste is about 1000 kcal, and about 3 cubic meters of gas can be generated per kilogram of waste; Due to the complete consumption of charcoal, only residual ash remains (some municipal solid waste pyrolysis furnaces advertise that they also produce charcoal, but this is also because the slag discharge is too fast, and the charcoal is not completely burned out. If there is charcoal, it is not good charcoal). At present, the thermal decomposition performance of small traditional household waste in China is extremely unstable and cannot be widely applied, while the thermal decomposition of large traditional household waste has extremely unsafe factors and is trapped by ash, floating ash, and tar.

Principle of Thermal Cracking of Low Temperature and Oxygen in Household Waste

Thermal cracking of household waste with low or no oxygen content is the process of producing combustible gases, charcoal, wood vinegar, and tar from the waste under thermal conditions that isolate oxygen.

The process of producing combustible gases during the thermal cracking of municipal solid waste is only a part of the cracking reaction in the thermal cracking furnace. The carbon in the waste does not participate in the reaction, as long as it can provide a cracking reaction temperature of 225-600 ℃. The reaction mechanism is as follows: hemicellulose mainly precipitates volatile components at 225-350 ℃; Cellulose mainly releases volatile components at 325-375 ℃; Lignin releases volatile components at 250-570 ℃,

The combustible gas produced by the thermal cracking of household waste with low temperature and oxygen content is mainly volatile gas, so its calorific value is relatively high. The calorific value of combustible gas per cubic meter of garbage is about 2000 kcal, and about 1.5 cubic meters of combustible gas can be produced per kilogram of garbage; The ash content of charcoal is very low, and its calorific value is generally around 8000 kcal/kg. It has a wide range of uses and a high price; The quality of wood vinegar and tar is also good. A reasonable garbage pyrolysis furnace has stable performance and good safety.