EA008270B1 - A method of converting organic wastes into fuels - Google Patents

Abstract

The method is applicable to the utilization of organic wastes through their gasification into synthesis gas with subsequent catalytic conversion of synthesis gas obtained into liquid synthetic motor fuels and (or) valuable chemical products. The method includes a stage of treatment of the wastes with gasifying agent containing oxygen, water vapor and (or) carbon dioxide, at which synthesis gas is obtained, which is subsequently compressed, subject to deep purification from mechanical impurities and compounds of sulphur, nitrogen and heavy metals. Then synthesis gas or synthesis gas mixed with liquid organic wastes is fed into a reactor for synthesis of hydrocarbons and converted into liquid motor fuels and components of basic oils with help of a polyfunctional catalyst. The method is characterized in that the first stage of gasification is realized for volumetric ration of organic wastes/activated gas within the interval from 5 to 30 and at temperature 600 - 1,000°C under the action of modulated high-frequency fields in the frequency range from 1 MHz to 50 MHz at modulation frequency in the range from 0.5 KHz to 100 KHz, and at the second stage the gasification takes place under the action of no less than two single-electrode high-frequency discharges generated permanently in the central and upper parts of the reactor, where the synthesis gas obtained after the gasification is subject to purification in the presence of non-homogeneous variable electromagnetic fields and non-equilibrium plasma and converted into liquid motor fuels with the help of a polyfunctional catalyst containing oxides of iron, zinc and molybdenum in combination with a carrier of aluminium, its oxides and phosphates.The gaseous hydrocarbons obtained in the process of synthesis of motor fuels from synthesis gas are subject to oligomerization for producing liquid hydrocarbons, this being performed in the presence of a molybdenum-containing catalyst.

Description

Application area

A method of processing organic waste into motor fuels relates to the field of disposal of these wastes by gasifying them into synthesis gas, followed by catalytic conversion of the resulting synthesis gas into liquid synthetic motor fuels and / or valuable chemical products.

State of the art

A known method of processing organic waste, including their treatment with a gasifying agent, is oxygen (air), water vapor and / or carbon dioxide. Next, the resulting gas mixture is subjected to cleavage at a temperature of 950-1050 ° C for 1 s, resulting in the production of degradation products, which are introduced into water at a temperature of 200-800 ° C for separation into synthesis gas and low molecular weight compounds. The synthesis gas is treated in the presence of a catalyst and liquid hydrocarbons or alcohols, gaseous hydrocarbons and CO ₂ are obtained [1].

Closest to this invention and its prototype is a method of processing organic waste, which consists in treating them with a gasifying agent (oxygen, water vapor and / or carbon dioxide) in the presence of combustible gas [2]. Natural gas is used as a combustible gas at a volume ratio of oxygen / natural gas of 0.01-0.5. The synthesis gas obtained after gasification is compressed and subjected to deep purification from mechanical impurities, sulfur and nitrogen compounds, and from heavy metals. Then the compressed purified synthesis gas or synthesis gas together with liquid organic waste is fed to a hydrocarbon synthesis reactor, where in the presence of a bifunctional catalyst containing zinc and chromium oxides, or zinc, chromium and copper, or iron, or cobalt and ruthenium, with an acid component - zeolite type ZSM-5, Beta, modernite or silicoaluminophosphate, are converted into liquid motor fuels or into liquid motor fuels and oil base components. Waste gasification is carried out in a plasma-thermal manner, and urban wastewater sludge, partially dehydrated to a residual moisture content of not more than 50 wt.%, Is used as organic waste, and the precipitation is gasified with a mass ratio of oxygen to natural gas of 1:10. In example 2 of the prototype, urban wastewater sludge is dehydrated to a residual moisture content of 55 wt.%, Heated to a temperature of 500-800 ° C and, together with natural gas and oxygen, with a mass ratio of BIO / natural gas U ₂ = 8: 1: 0.01 is fed to gasification into a plasma reactor (plasmatron), where at a temperature of 11001300 ° C there is a 99% decomposition of organic compounds to CO, CO ₂ and H ₂ . The resulting gas mixture (synthesis gas) is cooled by heat recovery, compressed and purified from mechanical impurities, sulfur and nitrogen compounds and heavy metals. Hydrogen-purified synthesis gas at a pressure of 80 atm is sent to a hydrocarbon synthesis reactor, where hydrogen is converted at a temperature of 360-420 ° С and in the presence of a bifunctional catalyst containing zinc and chromium oxides in combination with an acid component - zeolite type ZSM-5 and carbon oxides. The resulting products are cooled and separated in a separator into gas, water and hydrocarbon fraction. The resulting motor fuel is gasoline with an octane rating of 92, whose yield is 140 g per 1 normal m ^{3 of} synthesis gas with a conversion of carbon oxides of more than 90%. Gaseous by-products obtained at the stage of hydrocarbon synthesis are sent to the fuel network of the enterprise. The described method has several disadvantages, namely:

to maintain the energy process of gasification of organic waste, it is necessary to use an additional energy carrier - natural gas or biogas, and the mass ratio of organic waste to natural gas in the processing of urban wastewater sludge is 1/10, which requires additional costs and worsens the economic performance of the process;

if municipal waste or urban sewage sludge is used as recyclable waste, its processing in a mixture with combustible materials selected from the following groups: fuel oil, used oil, heavy oil residues, coal sludge, is possible only when using natural gas or biogas as energy carrier, and this is unprofitable;

The process of gasification of organic waste of urban waste and urban sewage sludge is carried out in a plasma reactor at a temperature of 1100-1300 ° C, and under such conditions, the content of undesirable impurities, including nitrogen and sulfur oxides, in synthesis gas increases significantly, which requires an additional stage cleaning;

The process of gasification of organic waste of urban waste and urban sewage sludge is carried out at high temperatures - 1100-1300 ° C, which requires significant energy costs and increases the requirements for the materials of the gasification reactor, and this increases the cost of equipment.

Processing of synthesis gas obtained by gasification of organic waste (municipal waste or urban sewage sludge) at the stage of hydrocarbon synthesis is carried out using a bifunctional catalyst containing copper, zinc and chromium oxides in combination with zeolite type ZSM-5, or cobalt and ruthenium oxides in combination with zeolite ZSM-5, or iron oxides in combination with an acid component of zeolite type ZSM-5. The use of the zSM-5 type zeolite acid component as a carrier in all catalysts has the following disadvantages:

relatively high cost of zeolite type ZSM-5;

short service life of the catalyst based on zeolite ZSM-5;

- 1 008270 low coefficient of thermal conductivity of the catalyst based on the carrier of zeolite ZSM-5, characteristic of all oxides of the elements that make up the zeolites. Because of this, the process proceeds with a significant heat release - 11-12 MJ per kilogram of produced liquid hydrocarbons. Such heat generation requires more sophisticated equipment, and especially heat removal systems, which is difficult to achieve with low thermal conductivity of the catalyst and carrier [Radchenko M.N., Kagan D.N., Krechetova G.A., Syntetic Liquid Hydrocarbon Motor Fuel From Natural Gas M. IVTAN 1993, p. 223].

The presence in the obtained synthesis gas of a significant amount of chemical impurities containing nitrogen and sulfur compounds, which are undesirable components for the further stage of the catalytic synthesis of liquid hydrocarbons from synthesis gas, requires an additional stage of purification of the synthesis gas from these compounds.

All of the aforementioned disadvantages of the prototype do not allow to process the organic component of urban waste and urban sewage sludge with relatively high economic efficiency.

The objective of the invention is to provide a method of processing organic waste into fuel with improved quality of the resulting synthesis gas, increased efficiency of the synthesis of liquid hydrocarbons and optimized operation of the catalyst with simplified equipment for implementing the method.

The technical essence of the invention

This goal is achieved by creating a method of processing organic waste into motor fuels, including the stage of waste treatment with a gasifying agent containing oxygen, water vapor and / or carbon dioxide, resulting in synthesis gas, which is then compressed, subjected to deep purification from mechanical impurities and compounds of sulfur, nitrogen and heavy metals. Next, the purified synthesis gas or synthesis gas with liquid organic waste is fed to a hydrocarbon synthesis reactor and, in the presence of a multifunctional catalyst, is converted into liquid motor fuels and oil base components. It is characteristic that the first stage of gasification is carried out at a volume ratio of organic waste / activating gas in the range from 5 to 30 and a temperature of 600-1000 ° C under the influence of modulated high-frequency fields in the frequency range from 1 to 50 MHz with a modulation frequency in the range from 0, 5 to 100 kHz. The second stage of gasification is carried out under the influence of at least two single-electrode high-frequency discharges continuously generated in the middle and upper parts of the reactor. The synthesis gas obtained after gasification is subjected to purification in the presence of inhomogeneous alternating electromagnetic fields and non-equilibrium plasma and is converted into liquid motor fuels using a multifunctional catalyst containing iron, zinc, molybdenum oxides in combination with a carrier - aluminum, its oxides and aluminum phosphate.

Hydrocarbon gases obtained during the synthesis of motor fuels from synthesis gas can undergo oligomerization to produce liquid hydrocarbons; this is carried out in the presence of a molybdenum-containing catalyst.

The advantages of the method of processing organic waste into fuels are the increased quality of the resulting synthesis gas, the increased efficiency of the synthesis of liquid hydrocarbons and the optimized operation of the catalyst, which simplifies the equipment needed to implement the method.

Exemplary Execution and Effect of the Invention

The method is carried out using known typical installations. The stage of high-frequency gasification by treatment of waste with modulated high-frequency fields and the stage of plasma-chemical gasification by exposure to waste of highly nonequilibrium plasma of single-electrode high-frequency discharges that are directly generated in a vapor medium are included. In this way, a gas mixture of synthesis gas and solid inorganic products is obtained, and subsequently the synthesis gas is subjected to catalytic processing into gaseous and liquid hydrocarbons. In this case, the gasifying agent contains oxygen, water vapor or carbon dioxide. The resulting synthesis gas is subjected to purification from mechanical impurities, compressed and subjected to high-frequency plasma-chemical purification from the contents of nitrogen, sulfur and heavy metals by exposure to modulated high-frequency electromagnetic fields and plasma of single-electrode high-frequency discharges generated in various parts of the purification apparatus. Next, the purified synthesis gas is fed to a hydrocarbon synthesis reactor and converted into liquid motor fuels or into liquid motor fuels and oil base components using a multifunctional catalyst containing iron, zinc and molybdenum oxides in combination with a carrier - aluminum, its oxides and aluminum phosphate . At the same time, the organic component of urban waste or urban sewage sludge is used as recyclable material.

The process is carried out with a mass ratio of active gas / waste in the range of 10/4. Then, synthesis gas under a pressure of 30-50 atm (3-5 MPa) is sent to a hydrocarbon synthesis reactor, where at a temperature of 220-340 ° C and in the presence of a multifunctional catalyst, hydrogen and carbon oxides are converted into liquid motor fuels and / or oil bases . Gaseous by-products from the hydrocarbon synthesis step are sent to the catalytic oligomerization reactor to produce a high octane additive.

Distinctive features of the invention are the following.

Organic waste gasification using a mixture of oxygen, water vapor and / or carbon dioxide as an agent in the first stage is carried out under the influence of modulated high-frequency fields in the frequency range from 1 to 50 MG c with a modulation frequency in the range from 0.5 to 100 kHz.

The subsequent process of gasification of organic waste is carried out under the influence of high-frequency fields and plasma of single-electrode high-frequency discharges, continuously generated in different parts of the reactor.

The conversion of synthesis gas into synthetic motor fuels is carried out in the presence of a multifunctional catalyst containing iron, zinc, molybdenum oxides in combination with a carrier of aluminum, its oxides and aluminum phosphate.

The choice of conditions for gasification of waste is determined empirically, based on the maximum conversion of the organic components of municipal solid waste.

Another important factor in determining the optimal gasification conditions is the production of synthesis gas, the composition of which, namely the H ₂ / CO ratio, is most favorable for the further synthesis of hydrocarbons. At the same time, gasification conditions that contribute to the maximum conversion of the organic components of municipal solid waste may not correspond to the conditions under which the synthesis gas of the optimal composition is obtained. For example, increasing the gasification temperature increases the conversion depth of organic waste, however, at temperatures above 1000 ° C, there is an increase in the formation of by-products, in particular nitrogen oxides, which are undesirable impurities in the final product - synthesis gas.

An increase in the oxygen content in the gas-vapor mixture used for gasification leads to an increase in the carbon dioxide content in the resulting synthesis gas with a simultaneous decrease in the hydrogen content.

The addition of carbon dioxide increases the content of carbon monoxide in the resulting synthesis gas.

In the process of gasification of the organic component of municipal solid waste using a mixture of oxygen, carbon dioxide and water vapor as a gasification agent, synthesis gas is formed with a low hydrogen content (15-50 vol.%) And a high content of carbon monoxide (3050 vol.%). Such a composition of the synthesis gas is not optimal for the production of hydrocarbons from it by the Fischer-Tropsch reaction (the optimal ratio of hydrogen / carbon monoxide is 2: 2.5). In the prototype, in order to increase the hydrogen content in the resulting synthesis gas, energy is additionally supplied to the gasification reactor and natural gas is additionally added.

The use of water vapor instead of oxygen requires an additional supply of heat in the gasification reactor. In the prototype, this is achieved by introducing into the reactor energy additives: natural gas, fuel oil, coal, sawdust. To supply additional energy to the reactor, it is proposed to use the plasma-thermal method of gasification at a temperature of 1200-1300 ° C. Moreover, the degree of conversion of organic waste reaches 96-99%.

However, the implementation of the gasification process at such high temperatures is always accompanied by the formation of a significant amount of by-products in the synthesis gas, which reduces the degree of conversion of organic waste.

In addition, gasification conditions significantly depend on the composition of the organic part of municipal solid waste. The composition of the organic part, in turn, depends on the characteristics of transportation, sorting and storage of waste.

The above shows that the selection of optimal gasification conditions is carried out empirically for various types of household waste and various modes of gasification.

Example 1

Organic waste is dewatered to a residual moisture of 50-60%, is heated to a temperature of 500-600 ° C and fed to the gasification stage where the mixture is treated with water vapor, oxygen and carbon dioxide at a ratio of: waste / H ₂ O / C0 _{2/0 2} = 20/2 / 0.5 / 0.5. The gasification process is carried out at a temperature of 800 ° C in two stages: the first is carried out under the influence of modulated high-frequency fields with a carrier frequency of 1.76 MHz and a modulation frequency of 0.5 kHz, and the second under the action of two single-electrode high-frequency discharges continuously generated in the middle and upper parts of the reactor. At the same time, the organic component of household waste decomposes by 90% to CO, CO ₂ and H ₂ . The synthesis gas obtained after gasification is subjected to purification in the presence of inhomogeneous alternating electromagnetic fields and non-equilibrium plasma, then it is cooled, purified from mechanical impurities, compressed and sent to a hydrocarbon synthesis reactor at a temperature of 300 ° C and a pressure of 30 atm. The synthesis of liquid hydrocarbons proceeds in the presence of a multifunctional catalyst containing iron, zinc and boron oxides in combination with a carrier - aluminum and its oxides. The total yield of motor fuels is 190 g per 1 normal m ^{3 of} synthesis gas with a conversion of carbon oxides of 98%.

- 3 008,270

Example 2

Organic waste is dewatered to a residual humidity of 50-60% and is fed to the gasification stage where the mixture is treated with water vapor, oxygen and carbon dioxide in a ratio of: waste / H ₂ O / C0 _{2/0 2 = 30/2} / 0.5 / 0 ,5. The gasification process is carried out under conditions similar to Example 1. In this organic components of municipal waste 80% decomposed to CO, C0 ₂ and H _2. The synthesis gas obtained after gasification is subjected to purification from mechanical and chemical impurities, compressed and sent to a hydrocarbon synthesis reactor at a temperature of 300 ° C and a pressure of 30 atm. The synthesis of liquid hydrocarbons proceeds in the presence of a multifunctional catalyst containing oxides of iron, zinc and molybdenum in combination with a carrier - aluminum, its oxides and phosphates. The total yield of motor fuels is 190 g per 1 normal m ^{3 of} synthesis gas with a conversion of carbon oxides of 98%.

Example 3

Organic waste is dehydrated to a residual moisture content of 60%, heated to a temperature of 800 ° C and fed to the gasification stage, where it is treated with a mixture of water vapor, oxygen and carbon dioxide at a ratio of: waste / Н2О / С02 / 02 = 20/2 / 0.5 / 0.5. The gasification process is carried out in two stages: the first is carried out under the influence of modulated high-frequency fields with a carrier frequency of 30 MHz and a modulation frequency of 50 kHz, and the second is carried out under the influence of two single-electrode high-frequency discharges continuously generated in the middle and upper parts of the reactor. At the same time, the organic component of household waste decomposes by 96% to CO, CO2 and H2. The synthesis gas obtained after gasification is subjected to purification in the presence of inhomogeneous alternating electromagnetic fields and non-equilibrium plasma, then it is cooled, purified from mechanical impurities, compressed and sent to a hydrocarbon synthesis reactor at a temperature of 300 ° C and a pressure of 30 atm. The synthesis of liquid hydrocarbons proceeds in the presence of a multifunctional catalyst containing oxides of iron, zinc and molybdenum in combination with a carrier - aluminum, its oxides and phosphates. The total yield of motor fuels is 190 g per 1 normal m ^{3 of} synthesis gas with a conversion of carbon oxides of 98%. Hydrocarbon gases obtained in the synthesis of motor fuels from synthesis gas are sent to the oligomerization stage, which proceeds at a temperature of 240 ° C and a pressure of 5 atm, in the presence of a catalyst containing molybdenum in combination with a carrier - aluminum and its oxides. The resulting mixture of liquid hydrocarbons (oligomers) with an octane number of 90 is used as a high-octane additive to motor fuels.

Example 4

Organic waste is dehydrated to a residual moisture content of 60%, heated to a temperature of 800 ° C and fed to the gasification stage, where it is treated with a mixture of water vapor, oxygen and carbon dioxide at a ratio of: waste / Н2О / С02 / 02 = 20/2 / 0.5 / 0.5. The gasification process is carried out in two stages: the first is carried out under the influence of modulated high-frequency fields with a carrier frequency of 50 MHz and a modulation frequency of 90 kHz, and the second is carried out under the influence of two single-electrode high-frequency discharges continuously generated in the middle and upper part of the reactor. At the same time, the organic component of household waste decomposes by 92% to CO, CO ₂ and H ₂ . The synthesis gas obtained after gasification is subjected to purification in the presence of inhomogeneous alternating electromagnetic fields and non-equilibrium plasma, then it is cooled, purified from mechanical impurities, compressed and sent to a hydrocarbon synthesis reactor at a temperature of 300 ° C and a pressure of 30 atm. The synthesis of liquid hydrocarbons proceeds in the presence of a multifunctional catalyst containing oxides of iron, zinc and molybdenum and a combination with a carrier - aluminum, its oxides and phosphates. The total yield of motor fuels is 190 g per 1 normal m ^{3 of} synthesis gas with a conversion of carbon oxides of 98%.

Claims (2)

CLAIM 1. A method of processing organic waste into motor fuels, including a stage of processing waste gasifying agent containing oxygen, water vapor and / or carbon dioxide, resulting in a synthesis gas, which is then compressed, subjected to deep purification from mechanical impurities and sulfur compounds, nitrogen and heavy metals, then purified synthesis gas or synthesis gas with liquid organic waste is fed to the hydrocarbon synthesis reactor and in the presence of a polyfunctional catalyst is converted into liquid motor fuels and oil base components, characterized in that the first stage of gasification is carried out with a volume ratio of organic waste / activating gas in the range from 5 to 30 and a temperature of 600-1000 ° C under the influence of modulated high-frequency fields in the frequency range from 1 to 50 MG c with a modulation frequency in the range from 0.5 to 100 kHz, and the second stage of gasification is carried out under the influence of at least two single-electrode high-frequency discharges continuously generated in the middle and upper parts of the reactor, with the resulting gasification synthesis gas is purified in the presence of nonhomogeneous variable electromagnetic fields and non-equilibrium plasma and is converted into a liquid fuel via a polyfunctional catalyst containing iron oxides, zinc and molybdenum in combination with a carrier - aluminum, its oxides and phosphate - 4 008270 aluminum. 2. The method according to claim 1, characterized in that the hydrocarbon gases obtained in the process of synthesis of motor fuels from synthesis gas, is subjected to oligomerization to obtain liquid hydrocarbons, and this is carried out in the presence of a molybdenum-containing catalyst.