DE3107326A1 - Method of producing synthesis gas - Google Patents

Abstract

Synthesis gas is produced by subjecting a mixture of low-grade solid fuel and petroleum coke to partial oxidation.

Description

METHOD FOR PRODUCING SYNTHESIS GAS

Process for the production of synthesis gas The invention relates to on a process for the production of synthesis gas, namely from carbonaceous Solid fuels.

Synthesis gas, a mixture of carbon monoxide and hydrogen, can pass through Partial oxidation of gaseous or liquid hydrocarbons by means of a Oxidizing gases such as air, oxygen, or oxygen-rich air that normally has an oxygen content of about 40% or more. The raw synthesis gas, the Z. B. from the packed non-catalytic reaction zone of a synthesis gas generator or partial oxidation reactor exits at a temperature of approx. 982-1760 OC, essentially comprises CO and H2 as reaction products with smaller amounts of H20, C02, CH4 and, if the raw material contains sulfur, hydrogen sulfide and Carbonyl sulfide.

The amount of nitrogen contained in the product gas depends to a large extent on the nitrogen content of the oxygen-containing gas.

Syngas mixtures are industrially important as a hydrogen source for hydrogenation reactions and as a starting gas for the synthesis of hydrocarbons, oxygen-containing organic compounds or ammonia.

As a result of the scarcity of petroleum products, steps are taken to save of fuel, in particular to save natural gas, which is used as fuel in power plants. There were extensive Considerations made with regard to the conversion of such power plants to the Use of solid fossil fuels. However, environmental protection regulations limit in many places the relative amounts of sulfur compounds and nitrogen oxides that are found in the atmosphere may be released. A large number of industrial heaters and boilers, including those from large utilities such as electric companies, are designed to burn gaseous fuels such as natural gas and not easily convertible to the direct combustion of other fuels. Fundamental Design factors that are involved in the design and construction of gas-fired heat exchangers and boilers are considered, their use as coal-fired boilers are available and heat exchangers. Most electricity companies use natural gas for production used by steam which is discharged through turbines will so that Electricity is generated. Since synthesis gas can be generated relatively sulfur-free, was it was proposed as a fuel used to generate steam or burned Could be taking the products of combustion through a turbine to generate electricity are derivable; this would result in only a very small amount of SO2 being released into the atmosphere take place. However, to keep the nitrogen oxide emissions within the specified values and to ensure satisfactory operation of the plant synthetic gas with a calorific value between approx.

3731.4 and 5891.7 k3 / Nm3 (approx. 95-150 BTU / SCF) can be used. Unfortunately Many solid fuel stores are made of inferior material such as subbituminous Coal or lignite together, which in the case of partial oxidation with air do not Result in gas with a sufficiently high calorific value.

The invention provides a method of manufacture of synthesis gas, which is harmless to the environment when burned; this is an aqueous Slurry with about 50-75 wt .-% fuel, the subbituminous coal and / or Lignite is, and between approx. 25 and 50 Ge.-X petroleum coke is the partial oxidation with an oxygen-containing Subjected to gas, and it becomes a synthesis gas generated, which has a calorific value of approx. 3731-5891 k3 / Nm3; from the synthesis gas produced in this way sulfur compounds are removed.

The raw material fed into the process consists of a mixture from petroleum coke and an inferior solid fuel like subbituminous coal or lignite. Suitable coals are e.g. B. subbituminous Colorado or Montana coal, Montana lignite, North Dakota lignite, Texas lignite, and subbituminous Wyoming coal.

Petroleum coke usually consists of very small graphite-like crystals, which like in an organic matrix of highly condensed aromatic compounds Anthracene, chrysene and the like are embedded. Petroleum coke intended for use as a one of the starting materials for the process according to the invention is suitable, can be generated according to the delayed koking method; this is a special procedure for converting heavy residual heating oil into petrol, gas oil and coke. The petroleum coke but can also be produced by other petroleum coking processes with which a Petroleum coke with a similar structure and chemical analysis is obtained.

The carbonaceous solid fuel is ground to such a particle size that 100% a sieve with a mesh size of 1.42 mm and preferably at least 60% pass through a sieve with a mesh size of 0.074 mm. The size of the Solid fuel particles is important in terms of ensuring a uniform suspension that does not settle in the liquid carrier medium as well as an essentially complete gasification as well as the simultaneous achievement high solids pumpable slurries.

The partial oxidation of the raw material takes place in the reaction zone of the synthesis gas generator at a temperature of approx. 982-1926 OC, preferably 1093-1538 OC, and a pressure in the range of approx. 7.9-207 bar, preferably 42-84 bar. The atomic ratio from free oxygen to carbon in the starting material is in the range of approx. 0.7-1.6, preferably 0.8-1.4, and the weight ratio of water to fuel in the reaction zone is about 0.2-3.0, preferably 0.5-1.0.

In the process of the invention, there is preheating of the reactants not mandatory. If desired, however, the oxidizing gas or the oxidizing gas-water vapor mixture, if used, heated to a temperature in the range of approx. 37.8-649 OC, around to reduce oxygen consumption. Likewise, the slurry can be at a temperature from about 37.8-316 OC to reduce the viscosity of the slurry and improve their pumpability.

The gasification of liquid slurries of carbon solid fuels can according to the method according to the invention using a ring burner, how he z. B.

in US Pat. No. 2,928,460. The front end of the The ring burner unit is placed in a compact, non-catalytic reaction zone free of packing a synthesis gas generator introduced. The front end of the burner has an inner conduit through which the liquid slurry is passed and that of an annular channel is surrounded by an oxidizing gas or an oxidizing gas-water vapor mixture is directed. Depending on the amount of water in the slurry, it can it may not be necessary to add steam to the oxidizing gas.

According to a preferred embodiment of the invention, the Mixture of liquid and solids through the inner line of a ring burner sent at a relatively low speed of approx. 1.5-15.2 m / s.

At the same time there is a convergent atomization stream of oxidizing gas at a relatively high speed in the Range from 60.9 m / s to the speed of sound sent at the burner head through a concentric ring channel of the burner. the both streams meet in front of the burner end wall, which is within the reaction zone of the gas generator lies on top of one another. The currents merge s-i and form one Atomized dispersion of water, carbonic solids and oxidizing gas.

Under synthesis gas generating conditions, the atomized dispersion is reacted to produce a gas mixture comprising hydrogen and carbon monoxide.

If there is a sulfur emission during the combustion of the synthesis gas produced occurs above the prescribed values, the synthesis gas can with a conventional Sour gas removal processes are treated, e.g. B.

with an ethanolamine solution, so that gases such as H2S and COS are separated will.

When the carburetor is running at high pressure, e.g. B. more than 7.9 bar operated the high pressure gaseous fuel product stream can be released from the pressure of the partial oxidation step be relaxed to an intermediate pressure, so that at the same time a cooling of the Heating gas flow and the generation of energy take place. The relaxed gas can then be subjected to complete combustion with air, the products of combustion be discharged through a turbine, so that further energy is generated.

The following examples serve to illustrate the invention. at in each experiment the oxidizing gas was air, and the insert was so finely ground that 60% by weight could pass a sieve with a mesh size of 0.074 mm.

Trial 1 The use here was Lake De Smet coal from Wyoming with the following analysis on a dry basis: Table 1 Carbon 51.82 wt% hydrogen 3.92 nitrogen 0.68 sulfur 1.20 oxygen 15.90 ash 26.48 "The coal was gasified by being as an aqueous slurry with 60 wt .-% solids in a Carburetor was initiated at an autogenous temperature of 1370 OC and one Pressure of 42.4 bar was maintained, where is the atomic ratio of oxygen to carbon 1.36 and the weight ratio of water to solids Were 0.667. The specific oxygen consumption was 22.87 Nm3 oxygen per 26.87 Nm3 hydrogen plus carbon monoxide, and 2.0% of the carbon of the feed appeared as unreacted carbon in the product.

The composition of the synthesis gas produced is given below: Table II carbon monoxide 9.34 mole percent hydrogen 7.06 carbon dioxide 10.69 water 20.08 Methane 0.02 argon 0.66 nitrogen 51.98 hydrogen sulfide 0.16 carbonyl sulfide 0.01 After the acid gases (C02 and H2S) had been separated off, this gas had a calorific value of 3012.6 k3 / Nm3.

Experiment 2 Here, a petroleum coke was used with the following final analysis: Table III Carbon 89.81 wt% Hydrogen 4.83 Nitrogen 2.67 Sulfur 1.26 Oxygen 0.52 Ash 0.91 The petroleum coke was gasified by being a 60 wt% slurry was fed to a gasifier in water, which was at a pressure of 42.4 bar and a Temperature of 1494 OC was maintained, with an oxygen-carbon atomic ratio of 1.23 and a water to solid weight ratio of 0.667 were used. The specific oxygen consumption was l6, Nm3 per 26.87 Nm3 H2 + CO, and 2.0% of the carbon contained in the insert appeared in the partial oxidation products as unreacted carbon.

Analysis of the product gas was as follows: Table IV Carbon Monoxide 16.08 mole percent hydrogen 8.90 carbon dioxide 7.68 water 10.59 methane 0.02 argon 0.71 Nitrogen 55.89 Hydrogen sulfide 0.12 Carbonyl sulfide 0.01 The calorific value of the product gas from experiment 2 after separation of the acid gases was 3876.7 k3 Nm3.

Based on a linear relationship, one would expect that a mixture of 82% coke and 18% lake deSmet coal combined the desired gas with one Calorific value of 3731.4 k3 / Nm3 would result. However, this would not be a particularly suitable one Solution, since only a small amount of coal would be used relative to the coke and it would be a long way off it is more advantageous to use a larger amount of the low-grade coal. In attempt 3, however, it is shown that the required amount of petroleum coke, i.e. H. 40%, essential is below the expected value of 82%.

Experiment 3 Here the use to the gasifier was a slurry from 40% water, 36% lake deSmet coal and 24% coke.

The dry solids analysis was as follows: Table V Carbon 67.01 wt% hydrogen 4.28 nitrogen 1.48 sulfur 1.22 oxygen 9.76 ash 16.25 The feed mixture was at a pressure of 42.4 bar and a temperature of 1369.4 OC, the oxygen-carbon atomic ratio being 1.24 and the specific oxygen consumption was 17.04 Nm3 per 26.87 Nm3 H2 + CO. Here, too, 2% of the carbon present in the feed appeared as unreacted Carbon in the partial oxidation products.

The analysis of the product gas was as follows: Tabel VI carbon monoxide 13.40 mol% hydrogen 8.94 carbon dioxide 8.99 water 14.94 methane 0.02 argon 0.68 nitrogen 52.88 hydrogen sulfide 0.14 carbonyl sulfide 0.01 after Separation of H2S and C02, the product gas had a calorific value of 3731.4 kJ / i4m3. The product gas is very suitable for generating energy. It can be a complete Combustion can be subjected to, the products of combustion either by a Turbine derived or used to generate steam for the purpose of generating energy will. If the partial combustion is carried out with a pressure of more than approx. 7.9 bar the product gas can be expanded by a gas turbine before it is burned will. The combustion of the synthesis gas results in negligible quantities of S02 and nitrogen oxides.

Claims (2)

Claims 1. Process for the production of synthesis gas by Partial oxidation of carbonaceous fuels with an oxygenated one Gas, characterized in that - that a solid fuel mixture of approx. 50-75% by weight subbituminous coal and / or lignite and approx. 25-50% by weight of coke is subjected to partial oxidation, and that if necessary, sulfur compounds are removed from the synthesis gas produced in this way. 2. The method according to claim 1, characterized in - that the mixture is introduced as an aqueous slurry into the partial oxidation zone.