CZ310536B6 - A method of increasing the hydrogen content in the gaseous fraction from the outlet of pyrolysis unit and an equipment to perform it - Google Patents

Abstract

The subject of the solution concerns a method of increasing the hydrogen content in the gas fraction from the output of a pyrolysis unit during the processing of materials by pyrolysis. The gaseous pyrolysis products are subjected to condensation separation, in which the gaseous hydrogen-methane fraction H2+C1 and the condensed liquid hydrocarbon fraction C2 and higher are separated, after which the gaseous hydrogen-methane fraction H2+C1 is taken for further processing in industrial applications and the liquid hydrocarbon fraction C2 and higher is subjected to further thermal cracking, in which it is thermally split into a gaseous hydrogen-methane mixture H2+Cx and a residual fraction, while the gaseous hydrogen-methane mixture H2+Cx is subsequently subjected to condensation separation again, in which another gaseous hydrogen-methane fraction H2+C1 is separated from the hydrogen-methane mixture H2+Cx, and the residual fraction from further thermal cracking is condensed and purified, thereby obtaining light oil and a carbon residue, which is disposed of. The subject of the solution further relates to a device for increasing the hydrogen content in the outlet of the gaseous fraction from the outlet of the pyrolysis unit (1), which includes a condensation separator (2), connected to an auxiliary pyrolysis unit (4) with an outlet (40) of the gaseous hydrogen-methane mixture H2+Cx and an outlet (41) of the residual fraction leading to a second condenser.

Description

Method for increasing the hydrogen content in the gas fraction from the output of a pyrolysis unit and device for carrying it out

Technical area

The invention relates to a method of increasing the hydrogen content in the gaseous fraction from the output of a pyrolysis unit during the processing of materials by pyrolysis, in which the organic input raw material is processed by pyrolysis, one of the output products of which is gaseous pyrolysis products containing a mixture of gaseous hydrocarbons and hydrogen and which are collected for industrial use or for the production of e-fuels.

The invention also relates to a device for increasing the hydrogen content in the outlet of the gaseous fraction from the outlet of a pyrolysis unit.

Current status

Commonly used pyrolysis gas can be characterized as a mixture of hydrocarbons with one to twelve carbon atoms per molecule, with hydrocarbons with more than four carbon atoms per molecule exhibiting a liquid state under normal conditions, i.e. their boiling point is higher than 0 °C at a pressure of 101.325 kPa.

Therefore, under the thermodynamic conditions occurring in current pyrolysis gas processing, storage, transport and shipping facilities, these substances can precipitate from the pyrolysis gas, forming hydrocarbon condensate, which can cause undesirable problems. In order to prevent or limit these undesirable conditions, the development of objective and reliable methodologies for determining not only the dew point of hydrocarbons, but also data characterizing the amount of hydrocarbon condensate formed under given thermodynamic conditions from the monitored pyrolysis gas has recently become increasingly important. The actual determination of the dew point of hydrocarbon condensate characterizes the temperature and pressure at which condensation can begin relatively accurately, but does not provide any data on the amount or volume of condensate that can form under given conditions.

Data related to the characterization of the amount and volume of condensates are also needed for the design of condensate processing and handling systems. The necessary follow-up information is knowledge of its composition, or rather its physico-chemical parameters. An undesirable effect of condensing hydrocarbons that has not been monitored much so far is their possible effect on plastic pipes, clogging of various filters, control or regulation sensors and nodes, or possible absorption of odorants during their condensation.

Before the advent of pyrolysis gas treatment, the dew points of hydrocarbons in the pipeline, or of natural gases available on the market, probably reached ambient temperatures (between 0 and 15 °C). Transporters collected condensates and developed their own methods for separating these condensates from the gas before delivering it to the customer. As pyrolysis gas treatment progressed and production increased, producers were able to replace existing procedures with more advanced technological units. The first equipment for treating pyrolysis gas at that time was compression equipment similar to air conditioning units and preceded the advent of refrigeration equipment. These devices compressed natural gas and cooled it using air or water exchangers so that the higher-boiling hydrocarbons condensed.

Currently, TPG 902 02 is used, entitled "Quality and testing of fuel gases with a high methane content, which are supplied through distribution networks to end customers. These new technical rules set out the basic requirements for the quality and testing of fuel gases with a high methane content. Technical rules developed on the basis of consensus

- 1 CZ 310536 B6 a number of organizations operating in the Czech Republic in the gas industry, which specify the requirement for hydrocarbon content expressed as a hydrocarbon dew point of 0 °C. The following standards are recommended for determining the hydrocarbon content expressed as a hydrocarbon dew point:

- ČSN 38 5569 Natural gas - determination of the dew point of hydrocarbons; and

- ČSN EN ISO 6570 1 to 3 Natural gas - determination of condensable hydrocarbon content, general requirements, gravimetric method, volumetric method, which replaces ČSN ISO 6570-1 (38 5575), ČSN ISO 6570-2 (38 5575) and ČSN ISO 6570-3 (38 5575).

As auxiliary methods usable in connection with the procedures discussed above, the following standards with procedures for determining the composition of natural gas can be mentioned, in which the parameter C6 is defined - i.e. the total content of hydrocarbons higher than n-hexane, including n-hexane:

- ČSN EN ISO 6974-3 (38 5506) Natural gas - determination of composition with defined uncertainty by gas chromatography - Part 3: determination of hydrogen, helium, oxygen, nitrogen, carbon dioxide and hydrocarbons up to C8 using two columns, C6 for laboratories and an on-line measurement system using two columns; and

- ČSN EN ISO 6974-5 (38 5506) Natural gas - determination of composition with defined uncertainty using gas chromatography - Part 5: determination of nitrogen, carbon dioxide and hydrocarbons C1 to C5 and C6+ for laboratories and on-line measurement system using three columns.

For additional calculations and information, the procedures specified in:

- ISO 20765-1 Calculation of thermodynamic properties; and

- ISO/TR 26762 Natural gas - gas and condensate allocation.

Pyrolysis gas produced by thermal decomposition of organic compounds without access to air contains a number of organic aromatic and aliphatic compounds with carbon numbers from C1 to C250. By partial condensation at atmospheric pressure, this pyrolysis gas is divided into two stages, where in the first stage a heavy fraction C10 to C250 with an admixture of reaction water is obtained, while this heavy fraction, so-called pyrooil, is used for energy purposes and the needs of the chemical industry. In the second stage, hydrocarbons of the C2 to C10 series, methane (C1) and hydrogen, i.e. the so-called light gas fraction, are obtained. This light gas fraction is in the gaseous phase at ordinary temperatures, so-called pyrogas, and contains more than 30% hydrogen, 15% methane and also hydrocarbons C2 to C10. Traces of reaction water may also appear in this light gas fraction. It is precisely the traces of reaction water in the form of gaseous moisture that make it impossible to use pyrolysis gases for processing by the low-temperature distillation method in order to increase the hydrogen content, because in the distillation equipment at temperatures of -100 to -185 °C, these traces of reaction water cause freezing and blockage of industrial plate heat exchangers, which is disadvantageous.

The aim of the invention is to eliminate or at least mitigate the disadvantages of the prior art, in particular to create a method and device for increasing the hydrogen content in the gaseous fraction obtained at the outlet of a pyrolysis unit.

The essence of the invention

The aim of the invention is achieved by a method of increasing the hydrogen content in the gaseous fraction obtained at the output of a pyrolysis unit, the essence of which lies in the fact that the gaseous pyrolysis products are subjected to condensation separation before being taken for industrial use or for the production of e-fuels, in which the gaseous hydrogen-methane fraction H2+C1 and the condensed liquid hydrocarbon fraction C2 and higher are separated by condensation, after which the gaseous hydrogen-methane fraction H2+C1 is taken for further processing in industrial applications and the liquid hydrocarbon fraction C2 and higher is

- 2 CZ 310536 B6 is subjected to further thermal cracking, in which it is thermally split into a gaseous hydrogen-methane mixture H2+Cx and a residual fraction, the gaseous hydrogen-methane mixture H2+Cx being subsequently subjected to condensation separation, in which the gaseous hydrogen-methane mixture H2+Cx is divided into another gaseous hydrogen-methane fraction H2+C1 and into a condensed liquid hydrocarbon fraction C2 and higher, and the residual fraction from the further thermal cracking is condensed and purified, thereby obtaining high-quality light oil, which is taken mainly for the industrial production of e-fuels, and a carbon residue, which is disposed of as waste.

The essence of the device for increasing the hydrogen content in the gaseous fraction obtained at the outlet of the pyrolysis unit consists in that it contains a condensation separator of the components of the gaseous pyrolysis products, which is formed by a condensation separator for the condensation separation of the gaseous hydrogen-methane fraction H2+C1 and the condensed liquid fraction C2 and higher, wherein the condensation separator is provided with an inlet for the gaseous pyrolysis products, an outlet for the gaseous hydrogen-methane fraction H2+C1 and an outlet for the condensed liquid fraction C2 and higher, wherein the outlet for the condensed liquid fraction C2 and higher is connected to the inlet of the auxiliary pyrolysis unit for further thermal splitting of the liquid fraction C2 and higher into a gaseous hydrogen-methane mixture H2+Cx and a residual fraction, wherein the auxiliary pyrolysis unit is provided with an outlet for the gaseous hydrogen-methane mixture H2+Cx, which is connected to the inlet for the gaseous hydrogen-methane mixture H2+Cx to The condensation separator and the auxiliary pyrolysis unit are further equipped with a residual fraction outlet, which is connected to the inlet of the second condenser for condensation and purification of the residual fraction into high-quality light oil for the industrial production of e-fuels and for separation of the carbon residue into waste.

In general, this invention is based on the principle of large-scale condensation of gaseous pyrolysis products using physical changes in the properties of hydrocarbons in the region of the critical point of hydrocarbons depending on temperature and pressure, when pre-cooling the gaseous phase of pyrolysis products, i.e. pyrolysis gas (pyrogas), exiting the pyrolysis unit next to the liquid phase of pyrolysis products, i.e. next to pyrooil, to a temperature at which condensation of all heavier hydrocarbons (C2 and higher) and free evaporation of the H2-C1 mixture occur in a cooled pressure tank. H2-C1 is taken in the form of gas for industrial use and the liquefied heavier hydrocarbons C2 and higher are subjected to further pyrolysis to form a gaseous hydrogen-methane mixture H2-Cx and a residual fraction. The hydrogen-methane mixture H2-Cx is subjected to condensation separation to separate the gaseous hydrogen-methane fraction H2-C1 to increase the hydrogen concentration at the outlet of the system. The residual fraction from this further pyrolysis is condensed and purified to obtain light oil, especially for the production of e-fuels, and to separate the carbon residue. In the cyclic mode, the light gaseous hydrogen-methane fraction H2-C1 at the outlet of the system is continuously enriched so that this hydrogen-methane fraction H2-C1 is suitable for subsequent separation of pure hydrogen H2 and hydrocarbon C1 on membranes and molecular sieves.

Clarification of drawings

The present invention is schematically illustrated in the accompanying drawings, in which it represents:

Fig. 1 is a general block diagram of a device for performing pyrolytic decomposition of materials with an included device for increasing the hydrogen content in the gas fraction from the outlet of the pyrolysis unit according to the present invention;

Fig. 2 is a diagram of a device for increasing the hydrogen content in the gaseous fraction from the outlet of a device for carrying out pyrolytic decomposition of materials according to the present invention; and Fig. 3 is a graphical representation of the physical change in the properties of hydrocarbons in the region of the critical point of hydrocarbons as a function of temperature and pressure, where this representation is sufficient for a person skilled in the art without further detailed explanation.

- 3 CZ 310536 B6

Examples of implementation of the invention

The invention will be described on the example of a method for increasing the hydrogen content in the gaseous fraction from the outlet of a pyrolysis unit and an example of a device for performing pyrolytic decomposition of materials, e.g. sewage sludge, TAP, biomass, industrial and municipal organic waste, etc., in which a device for increasing the hydrogen content in the gaseous fraction from the outlet of a pyrolysis unit according to the present invention is included as one of the technological nodes. The average expert is able to apply the device for increasing the hydrogen content in the gaseous fraction from the outlet of a pyrolysis unit according to the present invention even in differently structured devices for performing pyrolytic decomposition of materials.

The invention is based on the fact that organic input raw material, in particular sewage sludge, TAP, biomass, industrial and municipal organic waste, etc., enters the pyrolysis unit 1, one of the output products of which is gaseous pyrolysis products, so-called pyrogas, which contains a mixture of gaseous hydrocarbons and hydrogen. This gas mixture is subjected to condensation separation, here in the condensation separator 2, whereby the gaseous hydrogen-methane fraction H2+C1 and the condensed liquid hydrocarbon fraction C2 and higher are separated by condensation. The gaseous hydrogen-methane fraction H2+C1 is then taken for further processing in industrial applications, while the liquid hydrocarbon fraction C2 and higher is subjected to further thermal cracking, e.g. in the auxiliary pyrolysis unit 4, whereby this liquid hydrocarbon fraction C2 and higher is further thermally split into a gaseous hydrogen-methane mixture H2+Cx and a residual fraction. The obtained gaseous hydrogen-methane mixture H2+Cx is then subjected to condensation separation again, here again in the condensation separator 2, whereby the gaseous hydrogen-methane fraction H2+C1 for industrial use and the condensed liquid hydrocarbon fraction C2 and higher for further thermal cracking, e.g. in the auxiliary pyrolysis unit 4, and the process is thus cyclically repeated. The residual fraction from further thermal cracking, e.g. from auxiliary pyrolysis unit 4, is condensed and cleaned, here e.g. in cyclone 3, thereby obtaining high-quality light oil suitable for industrial production of e-fuels and a carbon residue, which is disposed of.

Fig. 1 shows an exemplary overall block diagram of a device for performing pyrolytic decomposition of materials, which includes a pyrolysis unit 1, which is provided with an outlet 10 of gaseous pyrolysis products, i.e. pyrogas, to which a condensation separator 2 of pyrogas components is connected by its inlet. The pyrolysis unit 1 is further provided with an inlet 11 of material for pyrolysis decomposition. The pyrolysis unit 1 is further provided with an outlet 12 of liquid pyrolysis products, so-called pyrooil, an outlet 13 of biochar, i.e. charred biomass from the pyrolytic decomposition of the material. The separator 2 of pyrogas components is provided with an outlet 20 of the liquid fraction of hydrocarbons C2 and higher formed by condensation separation of gaseous pyrolysis products. The outlet 20 of the liquid fraction of hydrocarbons C2 and higher is connected to the inlet of the auxiliary pyrolysis unit 4, which is provided with an outlet 40 of the gaseous hydrogen-methane mixture H2+Cx, which is connected to the inlet 27 of the gaseous hydrogen-methane mixture H2+Cx to the condensation separator 2 of the pyrogas components. The auxiliary pyrolysis unit 4 is further provided with an outlet 41 of the residual fraction, which is connected to the inlet of the cyclone 3 for separating carbon from the residual fraction and for condensing the residual fraction into the form of a high-quality light oil suitable for the production of e-fuels. The cyclone 3 is therefore provided with an outlet 30 of condensate and is further provided with an outlet 31 of the carbon residue. The pyrogas component separator 2 is further provided with an outlet 21 for gas for combustion (off-gas to the flare) and an outlet 22 for the gaseous hydrogen-methane fraction H2+C1 for further processing in industrial applications.

Fig. 2 shows an example of the implementation of a condensation separator 2 of pyrogas components for the condensation separation of gaseous H2 and gaseous hydrocarbons C1 to Cx from gaseous pyrolysis products. The condensation separator 2 of pyrogas components comprises a pressure tank 23, which is connected via a non-return valve 230 to the outlet 10 of gaseous pyrolysis products from the pyrolysis unit 1. The pressure tank 23 is for example provided with an optical sensor 231 of the level of condensate of hydrocarbons C2 and higher in the tank 23 and/or is provided with an ultrasonic or other remotely readable sensor 232 of the level of condensate of hydrocarbons C2 and higher in the tank 23. The pressure tank 23 is further provided with a cooling pipe 233, which is connected to the inlet 2330

- 4 CZ 310536 B6 and the outlet 2331 of the cooling medium and which is intended for maintaining the equilibrium condensation temperature for large-volume condensation of gaseous pyrolysis products using physical changes in the properties of hydrocarbons in the region of the critical point of hydrocarbons depending on temperature and pressure. In the illustrated embodiment, the pressure tank 23 is further provided with a control outlet 234 with a control valve 2340 and a bypass channel 2341. In the not illustrated embodiment, the pressure tank 23 is provided without a control outlet 234. In its lower part, the pressure tank 23 is provided with an outlet 20 for the condensate of hydrocarbons C2 and higher, i.e. the liquid fraction of hydrocarbons C2 and higher, from the pressure tank 23 to the auxiliary pyrolysis unit 4. The outlet 20 for the condensate of hydrocarbons C2 and higher from the pressure tank 23 to the auxiliary pyrolysis unit 4 is provided with a valve 200. The pressure tank 23 is further provided with an outlet 236 for the gaseous fraction H2+C1, which is connected to the gas fraction H2+C1 via a suction pressure control valve 2360, a check valve 2361, at least one filter, here for example a cascade of two filters containing a dust filter 24 and a safety filter 25, connected to a suction source 26 for the extraction of the H2+C1 fraction from the pressure tank 23 for further processing in industrial applications. The outlet of the suction source 26 is formed by the above-described outlet 22 of the H2+C1 gaseous fraction of the pyrogas component separator 2. The pressure tank 23 is further provided with an inlet 27 of the H2+Cx gaseous hydrogen methane mixture from the auxiliary pyrolysis unit 4.

The source 26 is preferably formed by a vacuum pump, ideally an oil-filled vane vacuum pump. The dust filter 24 is preferably formed by a labyrinth dust filter. The safety filter 25 is preferably formed by a safety textile filter. The dust filter 24 and the safety filter 25 are provided with a controllable outlet 240, 250 of the gas to be burned (exhaust gas to the flare).

The suction pressure control valve 2360 and the check valve 2361 serve primarily to prevent the backflow of liquids and gases during sudden changes in pressure in the condensation separator 2 and to protect the suction source 26 from damage by possible high suction pressure.

The specific device according to the examples of implementation described and shown here operates in such a way that organic raw material (sewage sludge, TAP, biomass, industrial and municipal organic waste, etc.) enters the pyrolysis unit 1, one of the output products of which is gaseous pyrolysis products, so-called pyrogas, which contains a mixture of gaseous hydrocarbons C1 and higher and hydrogen H2.

This mixture contains, for example, 33.5 wt. % hydrogen, 13 wt. % methane and 6 wt. % hydrocarbons C2 etc. This gas mixture is separated by a condensation separator 2 into a gaseous hydrogen methane fraction H2+C1 and a condensed liquid hydrocarbon fraction C2 and higher. The gaseous hydrogen-methane fraction H2+C1 is removed for further processing in industrial applications via the outlet 22 of the gaseous fraction H2+C1. The condensed liquid hydrocarbon fraction C2 and higher is fed via the outlet 20 to the auxiliary pyrolysis unit 4, where this liquid fraction C2 and higher is further thermally split into a gaseous hydrogen-methane mixture H2+Cx, here for example containing 52 wt. % hydrogen and 18 wt. % methane, and into a residual fraction. The residual fraction is fed to cyclone 3, at the outlet of which, after condensation and purification, it forms a high-quality light oil suitable for the industrial production of e-fuels and a carbon residue for waste. The gaseous hydrogen methane mixture H2+Cx obtained by the above-mentioned further thermal splitting of the liquid fraction C2 and higher is fed back to condensation separator 2 for condensation separation into a gaseous hydrogen-methane fraction H2-C1 and a condensed liquid hydrocarbon fraction C2 and higher, which in turn leads to an increase in the volume and concentration of gaseous H2-C1 at the outlet 22.

Industrial applicability

The invention is useful in the processing of waste and other suitable materials by pyrolysis to increase the quality of the output products, in particular to increase the hydrogen concentration in the output gas stream, for example up to 50%.

Claims (5)

PATENT CLAIMS 1. A method of increasing the hydrogen content in the gaseous fraction from the output of a pyrolysis unit during the processing of materials by pyrolysis, in which an organic input raw material is processed by pyrolysis, one of the output products of which is gaseous pyrolysis products containing a mixture of gaseous hydrocarbons and hydrogen, and which are collected for industrial use or for the production of e-fuels, characterized in that the gaseous pyrolysis products are subjected to condensation separation before collection for industrial use or for the production of e-fuels, in which the gaseous hydrogen-methane fraction H2+C1 and the condensed liquid hydrocarbon fraction C2 and higher are separated by condensation, after which the gaseous hydrogen-methane fraction H2+C1 is collected for further processing in industrial applications and the liquid hydrocarbon fraction C2 and higher is subjected to further thermal cracking, in which it is thermally split into a gaseous hydrogen-methane mixture H2+Cx and a residual fraction, wherein the gaseous The hydrogen-methane mixture H2+Cx is then subjected to condensation separation again, in which the hydrogen-methane mixture H2+Cx is separated into another gaseous hydrogen-methane fraction H2+C1 and into a condensed liquid hydrocarbon fraction C2 and higher, and the residual fraction from further thermal cracking is condensed and purified, thereby obtaining a light oil and a carbon residue. 2. Device for carrying out the method according to claim 1, characterized in that it comprises a separator of components of gaseous pyrolysis products, which is formed by a condensation separator (2) for condensation separation of gaseous hydrogen-methane fraction H2+C1 and condensed liquid fraction C2 and higher and which is provided with an inlet of gaseous pyrolysis products, an outlet (22) of gaseous hydrogen-methane fraction H2+C1 and an outlet (20) of condensed liquid fraction C2 and higher, wherein the outlet (20) of condensed liquid fraction C2 and higher is connected to the inlet of an auxiliary pyrolysis unit (4) for further thermal splitting of condensed liquid fraction C2 and higher into gaseous hydrogen-methane mixture H2+Cx and a residual fraction, wherein the auxiliary pyrolysis unit (4) is provided with an outlet (40) of gaseous hydrogen-methane mixture H2+Cx, which is connected to the inlet (27) of gaseous hydrogen-methane mixture H2+Cx into the condensation separator (2), and the auxiliary pyrolysis unit (4) is further provided with an outlet (41) of the residual fraction, which is connected to the inlet of the second condenser for condensation and purification of the residual fraction into high-quality light oil for the industrial production of e-fuels and for separation of the carbon residue into waste. 3. The device according to claim 2, characterized in that the condensation separator (2) comprises a pressure tank (23), which is provided with an inlet for gaseous pyrolysis products from the pyrolysis unit and is further provided with a cooling pipe (233), which is connected to the inlet (2330) and outlet (2331) of the cooling medium, wherein the pressure tank (23) is provided with an outlet (20) for the condensed liquid fraction C2 and higher to the auxiliary pyrolysis unit (4), and the pressure tank (23) is further provided with an outlet (236) for the gaseous hydrogen-methane fraction H2+C1, which is connected to a suction source (26) for withdrawing the gaseous hydrogen-methane fraction H2+C1 from the pressure tank (23), and the pressure tank (23) is further provided with an inlet (27) for the gaseous hydrogen-methane mixture H2+Cx from the auxiliary pyrolysis unit (4). 4. The device according to claim 3, characterized in that the outlet (236) of the gaseous hydrogen-methane fraction H2+C1 is connected to the suction source (26) for withdrawing the hydrogen-methane fraction H2+C1 from the pressure tank (23) via a suction pressure control valve (2360), a check valve (2361) and at least one filter. 5. The device according to any one of claims 3 or 4, characterized in that the pressure tank (23) is provided with at least one sensor (231, 232) for the level of the condensed liquid fraction C2 and higher in the tank (23). 6. The device according to any one of claims 3 to 5, characterized in that the pressure tank (23) is provided with a control outlet (234) with a control valve (2340) and a bypass channel (2341). 7. The device according to claim 3, characterized in that the suction source (26) for withdrawing the gaseous hydrogen methane fraction H2+C1 from the pressure tank (23) is formed by a vacuum pump, ideally an oil-filled vane vacuum pump. - 6 CZ 310536 B6 8. Device according to claim 4, characterized in that the filter is formed by a dust removal filter (24), preferably a labyrinth dust removal filter. 9. Device according to claim 8, characterized in that the dust filter (24) is supplemented with a safety filter (25), preferably a safety textile filter. 10. The device according to claim 2, characterized in that the second condenser is formed by a cyclone (3), which is provided with a condensate outlet (30) and a combustion gas outlet (31).