PL170924B1 - Method of gasifying solid, semi-solid and liquid residues and wastes - Google Patents

Abstract

A process for gasification of solid, pasty and liquid residues and waste substances, having a wide range of organic and inorganic noxious substances, comprises gasifying the residues and/or waste substances in a fixed bed pressure gasifier (1), with carboniferous condensates (15) and fine-grained ash (25) constituents from the solid bed gasification process being converted together with liquid residues eg spent oil (19), and/or waste substances in a flue current gasifier (23) and with the soot/water residue (30) from a quench (28) of the flue current gasifier (23) being returned to the fixed bed pressure gasifier (1). <IMAGE>

Description

The subject of the invention is a method of gasification of solid, pasty and liquid residues and waste, in which gasification takes place in parallel in a pressurized fixed bed reactor and in a fluidized bed reactor.

In the past, the least costly way to dispose of solid waste was to dispose of it in open landfills or in underground landfills. However, landfilling of untreated waste brings with it serious problems. The groundwater is easily contaminated by leaching. Valuable land is also lost and fires can occur.

A more advantageous way of reducing these problems is to fill the terrain irregularities (while maintaining sanitary standards) with composted waste and cover it with soil. However, this procedure in larger urban agglomerations becomes more and more difficult due to the lack of suitable places. Both of these methods are supplemented by burning garbage before throwing it into the ground basin.

While traditional waste incineration significantly reduces waste volume and reduces leaching pollution, new environmental problems arise, such as air pollution and an increased proportion of contaminated by-products such as filter dust and salt deposits.

While waste volume can be reduced by 80 to 90%, residues or ashes are not always biologically inactive, so it is still necessary to deposit them in the field. Moreover, with conventional incineration, material recovery is generally minimal.

The Anderson method (US patent PS 3 729 298) proposes a solution based on gasification of waste, where the waste is fed to the upper part and oxygen to the lower part of a vertically arranged shaft furnace. The shredded pieces are loaded into the furnace

170 924 waste without thickening it. The liquid slag formed in the lower part is continuously drained.

The disadvantage of this method is that the shredded waste compacts in the reactor, which obstructs the flow, reduces the efficiency of the process and causes an explosion.

German OS 26 19 302 proposes gasification in a shaft furnace of waste in the form of specific lumps made of shredded waste. The application of this method is limited to the gasification of specific lumps under normal pressure with discharge of liquid slag.

In German AS 2323 654 a method is described in which solid household waste is introduced into the upper part of the reactor and liquid hydrocarbon condensate from a gas purification plant and liquid waste is fed to the lower part of the reactor. The disadvantage of this method is that harmful organic and inorganic contaminants are not deliberately established or eliminated. With the proposed cooling of the gas to 300 ° C, another synthesis of dioxins and furans is not ruled out.

In the proposal according to the German description OS 3342 383, in a combined fluidized bed reactor and a pressure reactor with a fixed bed, gasification of the suspension is carried out in the primary process and in the secondary process the gasification of the material in pieces, with the resulting slag being transferred to the sodium carbonate bath. This method serves to avoid heavy metal, especially vanadium, reacting with the lining.

The disadvantage of this method is that narrow limits are placed on the input of solid and liquid waste and that only incomplete decomposition of hydrocarbons and / or dioxins in particular can occur in the secondary process.

The object of the invention is that the liquid, pasty and solid residues and / or waste, contaminated with inorganic and / or organic pollutants, can be used efficiently without contaminating the environment after processing in a pressure gasification process.

According to the invention, a pressurized fixed bed gas reactor and a fluidized bed gas reactor are operated simultaneously, with 1-80% solids or 1-60% solids and / or 1-20% pasty contents being converted into usable gas in the fixed bed reactor. coal, residues and / or waste contaminated with harmful organic substances, the time of heating the residues and / or waste in a reducing atmosphere to> 350 ° C and <400 < ⁵ C and the time of residues and / or waste in the pressure gas reactor for direct contact with a stream of crude gas produced, which has a temperature of> 350 ° C and is rapidly cooled down to <200 ° C after leaving the reactor, is greater than 1 hour

Solid and / or pasty residues and / or waste can be, for example: contaminated soil, plastic waste, wood, rubber products, oily solid waste, drug residues, tar residue, dye sludge, fine, pasty, sintered or sintered sewage sludge. in pieces, and may be contaminated with, for example, aliphatic, aromatic or chlorinated hydrocarbons, polychlorinated diphenols, dioxins, furans, sulfur compounds and heavy metals.

In the fixed-bed pressure gas reactor, volatile organic compounds are separated, which occur as hydrocarbon fractions when the raw gas is cooled in a closed system.

PCBs, dioxins and furans fully decompose when heated in an autoclave under a reducing atmosphere to> 1200 ° C. When a small amount of them comes out with the raw gas, these substances, due to their oil-bearing properties and oil solubility, end up in the liquid hydrocarbons separated in the condensation. They are converted into service gas without or together with liquid residue and / or waste contaminated organic substances in a gas fluidized reactor at a temperature> 1300 ° C and for> 3 s. This gas is cooled rapidly to <200 ° C after leaving the fluidized bed reactor. .

Liquid, pumpable residues or waste can be, for example: used oil, solvent, varnish and dye sludge as well as dye suspensions containing groups of harmful substances analogous to the above-mentioned groups.

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In the lower part of the pressurized fixed bed reactor, at a temperature> 1200 ° C, the resulting ashes are deliberately granulated into indelible smelting structures in which heavy metals contained in the charge are bound. Washable, fine-grained ash components are admixed in an amount of 1-30% to liquid residue and / or waste and are vitrified in a fluidized bed reactor at> 1300 ° C. At the same time, the binding of the non-volatile heavy metals of the liquid feedstock takes place.

Volatile heavy metals enter the water phase and are separated mainly as sulfides, oxides, hydroxides and carbonates.

During technological water treatment, these components are retained along with the biological sludge formed and are discharged to pressure gasification in order to bind with the slag. Throughout the process, the sulfur components are captured in a known manner from the gas stream and recovered as usable material.

The proposed method can provide comprehensive use of solid, pasty and liquid residues and / or waste, which has a positive effect on environmental protection. Thanks to the synergistic and combination effects, almost all of the waste is used with high efficiency of the transformation process. The gas generated in the decomposition process can be transported or stored as an energy source, or it can be directly processed into chemical raw materials.

An embodiment of the invention is shown in the drawing and described below.

10 t of brown coal briquettes 2, 3 t of contaminated earth 3 containing 5% hydrocarbons, dioxins in the amount of 2000 ng / kg and 800 mg of chromium / kg are introduced into the pressure gas reactor with a fixed bed 1, operating at a pressure of 2.5 MPa, 800 mg of lead, 600 mg Cu / kg, 3 t of plastic waste 3, 3 t of oil-contaminated wood 3, 0.5 t of residues from process water treatment 34.

Through the rotating grate 4, 2400 cm ^{J of} oxygen / h and 15.6 t of gasification steam / h are introduced into the gas reactor 1 as a mixture. The ash / slag mixture 6 is fed through the grate 4 to a sorter of known construction.

Here, the fine leachable ash 25 that appears can be separated off and fed to the mixer 24 for slagging in the gas fluidized bed reactor. The slag granules 36 formed in the pressure reactor and the fluidized bed reactor can be used as filler material or as construction aggregate. In a pressure gas reactor with a fixed bed, hydrocarbons contained in contaminated soil and wood are distilled off, decomposed and partially converted into usable gas. Dioxins contained in contaminated soil decompose in this reactor in a reducing atmosphere at a temperature of 300-800 ° C. When small amounts get into the hydrocarbon fraction of the condensate 17 - the final conversion takes place in the gas fluidized reactor 23.

50-70% of the plastic waste 3 contained in the gasified mixture in the pressure reactor is converted into gaseous components and in 20-50% into hydrocarbons. 2-5% is converted to ash / slag fraction 6.

Hydrocarbons contained in loaded old wood 3 and in the contaminated soil are distilled off, broken down or converted into gas. Wood 3 is gasified, the residual components of the earth with heavy metals become an indelible component of the ash / slag fraction 6.

The organic components of the process water treatment residue 3 are converted into a service gas, and the inorganic components are melted into an ash / slag mixture 6.

19700 m ^{3 of} dry raw gas / h containing oil and tar components in the amount of 80 g / m ³ and 0.7 kg of water vapor / m ³ pass through the crude gas collecting chamber 7, going through the raw gas outlet 8 to the scrubber cooler 9, here hot raw gas at 420 ° C is cooled to 195 ° C with cooling water in the amount of 20 cm3 / h. The cooled gas 11 in downstream coolers 12 is cooled with water 13 down to ambient temperature. The cooled raw gas 14 enters conventional gas purification plants and is then used as a material or energy medium.

The emerging condensates 15 are separated in the process water treatment 16 into process water fraction 31 into hydrocarbon fraction 17.

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About 1.58 t of hydrocarbons 17, pumped by pump 18, together with 12 t of used oil 19, which in the mixer 24 is mixed with 1.3 t of fine ash / h from pressure reactor 25 and additionally with 10,500 cm ^{3 of} oxygen / h 20 and 6 8 t of compressed steam / h 21 are introduced through a burner 22 into a gas fluidized reactor 23, where under a pressure of up to 25 MPa and at a temperature of 1350 ° C, it is converted into decomposition gas 26.

The gas decomposition in an amount of 26 45,000 m ³ / h is cooled to 195 ° C with water 27 in an amount of 60 t / h, the gas from the cooling chamber 29, goes through the stages of cooling and purification for use as a material or energy factor.

The resulting slag granulate 36 contains unleachable heavy metals from the charged ash and used oils and can be used in the construction industry.

The resulting soot water 30, together with the process water 31, is fed to the treatment system 32, which consists of various processing stages, such as dephenolation, soot filtration, and biological treatment stage. Appearing soot waste and biological sediments 34 are discharged to the reactor 1, which can use the process water, or to the sewage collector.

170 924

Publishing Department of the UP RP. Circulation of 90 copies

Price PLN 2.00

Claims (1)

Patent claim A method of gasification of solid, pasty and liquid residues and waste, carried out with parallel gasification in a pressurized fixed bed reactor and a fluidized bed reactor, characterized in that 1-80% solids or 1-60% solids and / or 1-20% pasty, containing coal, residues and / or waste saturated with harmful organic and / or inorganic substances are transformed in a pressure reactor with a fixed bed into a usable gas, with the heating time of the residues and / or waste in a reducing atmosphere to temperatures> 350 ° C and <400 ° C, as well as the residence time of the residues and / or waste in the pressurized fixed bed reactor until direct contact with the raw gas stream generated, which has a temperature of> 350 ° C and which, after leaving the autoclave, is rapidly cooled to <200 ° C , is greater than 1 h, and that the condensate formed during the cooling of the raw gas containing <25 ° C water without / or together with liquid residues and carbon-containing waste, which are saturated with harmful organic and / or inorganic substances, are transformed into a usable gas in a fluidized bed reactor, with the soot, heavy metal and salt residues arising in the gas and water treatment stages being discharged to the pressurized fixed bed reactor, and fine ash components from this reactor , in which heavy metal eluates can be found, are mixed with liquid residue and in an amount of 1-30% of the charge is charged to the fluidized bed reactor for slagging with additional binding of heavy metals contained in liquid residue and / or waste.