METHOD FOR PRODUCING HYDROGEN-CONTAINING GAS AND REACTOR FOR IMPLEMENTING SAID METHOD

Abstract

The invention is for use in gas chemistry for producing hydrogen-containing gas on the base of a CO and H.sub.2 mixture (syngas) from natural gas and other hydrocarbon gases. The object of the invention is to suppress side reactions resulting in soot formation when conducting the process in high productivity mode, and also to provide for an uncomplicated reactor design while maintaining compact dimensions thereof. The method for producing a hydrogen-containing gas comprises mixing natural gas with oxygen, partially oxidizing the natural gas with oxygen at a temperature ranging from 1300 C. to 1700 C. resulting in obtaining hydrogen-containing gas, and cooling the stream of the hydrogen-containing gas produced. Said cooling is performed until the temperature drops below 550 C. and at a rate above 100000 C./sec. The reactor comprises the following steps, which are arranged in series along the technological process: means for supplying natural gas and oxygen, a natural gas and oxygen mixing zone, a zone for conducting the reaction by partially oxidizing the natural gas with oxygen, and a zone for cooling the stream of the hydrogen-containing gas produced, which is equipped with a cooling body of revolution in order to provide an intensive cooling of the stream of hydrogen-containing gas by contacting thereof with said body of revolution.

Claims

1. A method for producing hydrogen-containing gas, said method comprising mixing natural gas with oxygen, partial oxidation of natural gas by oxygen at the temperature ranging from 1300 C. to 1700 C. to produce hydrogen-containing gas, and cooling the stream of obtained hydrogen-containing gas, where the stream of hydrogen-containing gas is cooled to the temperature lower 550 C. at the cooling rate more than 100000 C./s.

2. The method according to claim 1, where cooling the stream of hydrogen-containing gas is carried out by contacting said stream with a body of revolution.

3. The method according to claim 2, where the stream of hydrogen-containing gas has a linear velocity of at least 40 m/s when contacting with the cooled body of revolution.

4. The method according to claim 2, where water in the amount of at least 10 kg per 1 kg of hydrogen-containing syngas is injected in the stream of hydrogen-containing gas before contacting said stream with the cooled body of revolution.

5. The method according to claim 1, where mixing natural gas with oxygen and partial oxidation of natural gas by oxygen are carried out in a porous medium of a refractory material.

6. The method according to claim 5, where the refractory material is a ceramic material.

7. A reactor for producing hydrogen-containing gas, said reactor comprising successively arranged along the technological process: a means for feeding of natural gas and oxygen, a natural gas and oxygen mixing zone, a reaction zone for carrying out partial oxidation of natural gas with oxygen, and a zone for cooling the stream of obtained hydrogen-containing gas, where the cooling zone is provided with a cooled body of revolution to enable intensive cooling the stream of hydrogen-containing gas by contacting said stream with said body of revolution.

8. The reactor according to claim 7, where the cooled body of revolution has a streamline shape.

9. The reactor according to claim 7, where the reactor is provided with at least one injector to inject water in the cooling zone upstream from the body of revolution.

10. The reactor according to claim 7, where the mixing zone and reaction zone are filled up with porous refractory material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawing schematically shows a general view of the exemplary embodiment of the reactor according to the present invention in longitudinal section.

DETAILED DESCRIPTION OF THE INVENTION

[0035] In the embodiment shown in the drawing, the reactor for carrying out the method according to the present invention is made in the form of a vertical apparatus with the top feed of reagents, in which gas stream moves downward from the top. The reactor comprises successively arranged a means for supplying natural gas and oxygen made in the form of inlet assembly 1, a natural gas and oxygen mixing zone 2, a reaction zone 3 (zone for carrying out partial oxidation of natural gas with oxygen) comprising a combustion chamber 4, and cooling zone 5 for cooling the stream of obtained hydrogen-containing gas. The mixing zone 2 and reaction zone 3 (except the combustion chamber 4) are filled up with a porous refractory ceramic material. The cooling zone 5 comprises a first hollow and empty portion 6 and a second portion 7, in which a cooled body of revolution 8 is installed, arranged along the flow direction of the reaction products. The first portion 6 of the cooling zone 5 is provided with one ore more injectors 9 to inject water.

[0036] The method according to the present invention is carried out in the proposed reactor as follows.

[0037] Natural gas and oxygen pass through the inlet assembly 1 and enter into the mixing zone 2 filled up with the porous ceramic material, then the mixture enters into the combustion chamber 4, in which it is ignited by a spark or incandescent body, for example, a platinum filament, and then enters into the reaction zone 3, in which hydrogen-containing gas (syngas) is produced. Then, syngas is mixed with water injected through injectors 9 in the first portion 6 of the cooling zone 5 and enters into the second portion 7 of the cooling zone 5, in which the syngas is contacted with the cooled body of revolution 8, flowing around full circumference of the body of revolution 8 along its axis 10. That enables to remove the heat of the chemical reaction by convective heat transfer between syngas and cooling agent, such as water, through the wall of the cooled body of revolution 8, in which the heat transfer agent partially evaporates, thereby absorbing the transferred heat due to heat of evaporation.

[0038] As the numerous studies conducted by inventors of the present invention have shown (results of these studies are partially presented in the table below), to maintain optimum operating conditions of the reactor, at which the formation of by-products is not occurs, is possible by cooling the obtained syngas for a time no more than 5 ms, that is achieved, when the cooling rate of the syngas stream is more than 100000 C./s. To achieve these conditions, the hot hydrogen-containing gas entering in zone of flowing around the cooled body of revolution must have the velocity no less than 40 m/s.

[0039] Compared to known prior arts with the same output, the reactor according to the present invention enables the suppression of side reactions and, as a result, the formation of the cleaner product having the ratio close to stoichiometric, which is confirmed by the following examples of the embodiments of the present invention.

[0040] The following are examples of the embodiments of the non-catalytic method for producing hydrogen-containing gas by partial oxidation of natural gas with oxygen using the reactor according to the present invention at the various conditions. Examples 3, 4 and 8 relate to the method according to the present invention, and examples 1, 2, 5-7 are presented for the purpose of comparison. In all examples, reagents was fed in the reactor at the atmospheric pressure, and the density of obtained syngas was 0.065 kg/m.sup.3.

Example 1

[0041] Oxygen and hydrocarbon gas (methane) were fed in the flow reactor in a ratio close to stoichiometric at the atmospheric pressure. The flow reactor has the inner diameter of 25 mm, its mixing zone and reaction zone are filled up with the ceramic fill, for example, ball-shaped particles of the refractory corundum. The syngas obtained by the combustion reaction at the temperature higher 1300 C. and mass flow rate of 0.0001 kg/s was mixed with water injected through the injector in the amount of 0.0011 kg/s and supplied to the cooled body of revolution having the diameter of 20 mm at the ambient temperature that was lower 30 C. At the outlet of the reactor, the gas velocity was 12.8 m/s. In this case, the syngas was cooled to the temperature lower 550 C. within 18 ms, which did not give the desired result, as the soot was formed in this cooling time.

[0042] Other examples of the embodiments of the method are analogous to example 1, except that, in the example 5, mass flow rate of the syngas conforms to conditions of supersonic flow, that inevitably lead to destruction of the reactor parts and does not allow to carry out the syngas producing process, and examples 6-8 relate to reactions carried out without adding water (drip curtain) in the cooling zone.

[0043] The examples show, that carrying out the method according to the present invention enables to solve given technical problem, i.e. to provide the production of syngas by non-catalytic high-temperature partial oxidation of raw hydrocarbon gases with the suppression of side reactions.

[0044] The examples 1-2 and 6-7 show, that when the non-optimum mass flow rate of raw material is selected, the required velocity of the stream of reaction products, not necessarily added with water, may be not achieved before contacting the stream with the cooled body of revolution, which results in increased residence time of the reaction products in the zone of flowing around the cooled body of revolution until the temperature lower 550 C. is reached as well as creates conditions for side reactions, including the soot formation reactions.

TABLE-US-00001 TABLE Example No. Parameters 1 2 3 4 5 6 7 8 Syngas mass flow 1 .Math. 10.sup.4 2 .Math. 10.sup.4 5 .Math. 10.sup.4 1 .Math. 10.sup.3 2 .Math. 10.sup.3 5 .Math. 10.sup.4 1 .Math. 10.sup.3 2 .Math. 10.sup.3 rate, kg/s Syngas mass flow 0.36 0.72 1.80 3.60 7.20 1.80 3.60 7.20 rate, kg/h Syngas volume 0.78 1.57 3.94 7.88 15.75 3.94 7.88 15.75 flow rate nm.sup.3/h Water mass flow 0.0011 0.0022 0.0054 0.0108 0.0215 0 0 0 rate, kg/s Syngas velocity at 12.8 38 83.3 204.7 958.3 7.74 22.4 57.2 the outlet of the reactor, m/s Syngas cooling 42000 74000 181000 399000 843000 57000 89000 121000 rate, C./s Composition of 65 66 66.66 66.66 * 65 66 66.66 syngas, mol. % H.sub.2 CO 32 33 33.33 33.33 32 33 33.33 CO.sub.2 and H.sub.2O balance balance balance balance balance balance balance Content of >0.5 traces not not * 0.5 traces not soot, % w/w * Syngas velocity at the outlet of the reactor is more than the sound velocity, which does not allow to carry out the process because of destruction of the reactor parts at these conditions.