RU2688620C2 - Method for hydrothermal carbonisation of renewable raw materials and organic wastes - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to processing organic material by hydrothermal carbonisation, in particular wood, peat, shale, coal, industrial and domestic wastes, plant growing wastes, livestock farming, and can be used in chemical, forestry and oil refining, municipal and agricultural industries. Method is carried out by grinding and moistening starting material with concentration of water in formed mixture to 30–99 % and further supply of formed mixture by means of pump to reactor for treatment at temperature of 200 °C and pressure of 20 bar without air access and with addition of catalyst to carbonisation step to form carbonizate, which is dehydrated and briquetted. During dehydration of carbonizate, the extracted liquid is separated by electrodialysis into acid and water, after which acid is returned to the reactor as a catalyst and water is drained.

EFFECT: higher efficiency, avoiding the need for preliminary drying of biomass, possibility of using different types of biomass, including low-quality, simple maintenance of equipment, low operating costs and high environmental friendliness of the technology.

1 cl, 1 dwg, 1 ex

Description

The invention relates to the field of processing of organic raw materials, such as wood, peat, shale, coal, industrial and household waste containing organic components, crop waste, animal husbandry, etc., and can be used in the chemical, forestry and oil refining industries, municipal , agriculture and other industries by the method of hydrothermal carbonization.

The process of hydrothermal carbonization begins with the preparation of biomass: mechanical impurities (sand, stones, etc.) are removed from it, then crushed and moistened. Next, the biomass is sent to the reactor (retort), in which with the help of steam a pressure of 10-25 bar and a temperature of 180-220 ° C are created.

During the reaction, hydroxonium (hydroxonium, oxonium, hydronium) H ₃ O + (complex ion, compound of a proton with a water molecule) are formed, which reduce the pH of the reaction mixture to 5 and below. This process can be accelerated by adding a catalyst to the reactor.

The following can be used as a catalyst: 1) Brønsted inorganic acids: HNO3, HCl;

2) Bronsted organic acids: formic acid, acetic acid, citric acid, NH4Cl;

3) Lewis acids, such as, for example, metal halides: FeCl3, FeBr3, AlCl3, AlBr3;

4) common halides and oxides of metals: NaCl, FeO, Fe2O3, LiCl, [Fe (NH4) 2 (SO4) 2] -6 H2O.

Moreover, it should be noted that at low pH a greater amount of carbon passes into the liquid phase. The reaction is exothermic, that is, proceeds with the release of energy. After 12 hours, 90-99% of carbon goes into an aqueous suspension in the form of porous carbonisate (C ₆ H ₂ O) _N grains with a pore size of 8 to 20 nm.

The rest of the carbon (from 1 to 10%) partially remains in the liquid phase in the form of an aqueous suspension, is partially emitted into the atmosphere in the form of carbon dioxide. The reaction equation in a simplified form can be written in this form:

The reaction can be stopped earlier with obtaining other intermediate products. For example, after 8 hours, you can get a product similar in composition to peat, and in the first hour - hydrophobic intermediate products.

By means of mechanical pressing, the cooled coal suspension is dehydrated to such a state that 50-60% of the initial water content remains in it. Most of the separated water is used in subsequent production cycles. After mechanical dehydration, the product should be further dried to the moisture required by the customer; usually it is 5-25%.

The described technology of hydrothermal carbonization is used to one degree or another in the known methods of processing organic waste.

The known method of thermal processing of wood (RF patent No. 2083633, 11.24.1995, SW 53/02). The method includes pre-drying wood and subsequent heat treatment in the presence of gaseous coolant in a continuous process with the passage of successive drying zones, pyrolysis with the formation of charcoal, its calcining and cooling when countercurrently supplying a cooling agent, which is used as flue gases from complete combustion of fuel containing in them oxygen is 1.5-7.0%, while these gases after passing through the cooling zone are used as a coolant in the calcination zones, pi Roliza and drying.

The method described above is of low productivity, requires additional fuel and does not allow to process wood with a moisture content above 25%.

A known method for the production of charcoal and installation for the production of charcoal (RF patent No. 2166527, 02.01.2000, SW 53/02). The method includes pre-drying of raw materials and subsequent heat treatment in the presence of gaseous coolant in a continuous process with the passage of successive zones of drying, pyrolysis with the formation of charcoal and its calcination. The use of gas coolant in the pyrolysis zone dramatically reduces the concentration of wood-resin products in the steam-gas thermal decomposition of raw materials, increases their temperature and complicates the condensation system of bio-oil extraction.

There is also known a method and device for the dehydration of biomass together with liquid water at temperatures above 100 ° C (EP 1970431 A1) in which the biomass, if necessary, is heated and injected by means of a pump or sluice gate into a horizontal pressure reactor, through which it is moved using screw conveyor. The reactor under pressure is heated from the outside. The reacted biomass is removed at the end of the reactor under pressure or by means of a pump or transitional lock. The disadvantage of this technical solution is the use of a screw conveyor in order to move the contents of the reactor through the tubular reactor. Due to the high temperatures, the auger wears out quickly, and because of the high pressure, difficulties arise in isolating from the atmosphere.

The closest in technology to the claimed object is a method of hydrothermal carbonization of biowaste by crushing and moistening the raw materials, such as wood chips, to a concentration of water in the resulting pulp of up to 30 - 99%. Then the wood pulp is pumped to the reactor by means of a pump, where it is processed at a temperature of 200 ° C and at a pressure of 20 bar. In the reactor, biomass without air access and with the addition of a catalyst is dehydrated and carbonized to CO2 and neutral biochar. Biochar is a biomass, which is further dried and pressed into fuel briquettes (agrocontech.ru/ru/news/06-february-…).

This method of hydrothermal carbonization of organic waste was chosen as a prototype.

The disadvantage of the method chosen by us as a prototype is the high consumption of catalyst, which is periodically introduced into the reactor to ensure its stable and efficient operation during long-term production of biochar.

The aim of the invention is the possibility of using a previously inaccessible for full processing of a large amount of raw materials through improved redistribution of technology, in particular, a large amount of organic raw materials with high water content, through hydrothermal carbonization. In which the feedstock is converted by dehydration and carbonization, mainly into carbonized, water and CO ₂ , i.e. in auxiliary substances and fuels with high consumer value, for example, high calorific value and low content of water and ash.

The technical result of the invention is expressed in the expansion of the arsenal of methods and technical means of hydrothermal carbonization of renewable raw materials and organic waste. It is achieved by the fact that in the method of hydrothermal carbonization of renewable raw materials and organic waste, which involves crushing and moistening the feedstock with a water concentration in the resulting pulp up to 30-99% and then feeding the formed mixture using a pump to the reactor for treatment at 200 ° C and pressure of 20 bar without air access and with the addition of a catalyst to the stage of carbonization with the formation of carbonizate; when the feedstock is dehydrated, the separated liquid under the action of electrodialysis is divided into acid and water, followed by acid. feedback line as a catalyst is returned to the reactor, and the water is drained.

To implement the proposed method, a device is used, the block diagram of which is shown in the figure.

From the tank for raw material 1 by means of the pump 19, the raw material enters the intermediate tank 2. The valve 9 is shut off, from the intermediate tank 2 through the pump 20 the raw material mixed with acid supplied from the tank 3 through the pump 21 is fed to the reactor 4. The valve 12 is shut off and reactor 4. carbonation reaction occurs. Steam from reactor 4 is discharged through valve 11 to steam tank 25, which balances the pressure between reactor 4 and intermediate tank 2 by opening and closing valve 10. Carbonisate from reactor 4 through pump 22 is fed to breeder dryer 5. Valve 15 is blocked, excess moisture flows into the electrodialysis unit 6. The valve 16 overlaps, the water through valve 18 is drained from the electrodialysis unit 6 through drain 7, and the acid is fed through pump 24, valve 14 into tank 3, from where it goes through pump 21, valve 13 into intermediate tank 2. From wasp Ithel-briquetting 5 through the pump 23 is discharged to the finished product tank 8. Valve 17 is closed.

The continuous hydrothermal carbonization of biomass offered by us positively differs from all known methods of carbonizate production by higher efficiency due to the recirculation of catalysts, the absence of the need for pre-drying of biomass, the possibility of using various types of biomass, including low-quality composting, ease of equipment maintenance. low operating costs, high environmental friendliness uu preventing environmental pollution, the ability to use a mixture of different types of biomass.

Claims (1)

Method of hydrothermal carbonization of renewable raw materials and organic waste, which includes crushing and moistening the raw material with a water concentration in the resulting mixture up to 30-99% and then feeding the formed mixture using a pump into the reactor for processing at a temperature of 200 ° C and a pressure of 20 bar without air access and with the addition of a catalyst to the stage of carbonization with the formation of carbonizate, which is dehydrated and briquetted, characterized in that when the carbonizate is dehydrated, the released liquid is affected by m of electrodialysis is divided into acid and water, after which the acid in the feedback line as a catalyst is returned to the reactor, and the water is drained.

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