DE3101067A1 - "Process for generating ammonia synthesis gas according to the steam-reforming process" - Google Patents

Abstract

The invention relates to a novel process for generating ammonia synthesis gas, in which, in particular, the hitherto required autothermal reactor can be dispensed with, since blast-furnace top gas is used as the nitrogen carrier.

Description

"Process for the production of ammonia synthesis gas according to

the steam reforming process "The invention relates to a method according to the preamble of claim 1.

Such conventional methods of producing ammonia synthesis gas work in such a way that the feedstock, such as coke oven gas, natural gas, refinery gas, Liquid gas or naphtha in a tubular fission furnace with steam at reaction temperatures between 750 and 900 ° and reaction pressures up to 35 bar converted to cracked gas will. The setting of the hydrogen / nitrogen ratio takes place in one subsequent autothermal reactor, which operates at reaction temperatures between 900 and 11000 C works. In this reactor, the cracked gas becomes further catalytic by means of air split through; at the same time, the nitrogen content of the air increases the amount required Hydrogen / nitrogen ratio of the ammonia synthesis gas set. In the following process stages: normal conversion, low temperature conversion, C02 washing, Methanation, carbon monoxide is largely converted into hydrogen, the carbon dioxide washed out as well as the traces of CO and CO 2, which are necessary for the subsequent ammonia synthesis Represent catalyst poisons, transformed into methane.

The invention has a simplification and cheaper process management and a reduction in investment costs over the conventional one described above Aimed at ammonia synthesis gas process.

This goal is achieved by adding blast furnace top gas as Nitrogen carriers. Because the required nitrogen content for the ammonia synthesis gas is not introduced via process air, but via blast furnace top gas, can on the autothermal reactor, which is usually located downstream of the tube furnace, is dispensed with will.

Another advantage of this invention is that the maximum Process gas temperature 100-2000 (autothermal reactor) is lower, what influence on the material costs. The method according to the invention is also suitable equally for input materials such as coke oven gas, natural gas, refinery gas, liquid gas and naphtha.

If the process furnace gas according to claim 2 before the conversion If cracked gas is mixed in, this process control has the advantage that the gas generation system part with the associated heat exchangers can be dimensioned smaller than in Case of conventional ammonia synthesis gas production, in which the nitrogen must be supplied via the air to the autothermal reactor and thus to the process.

An example for the implementation of the method according to the invention with coke oven gas as the feedstock explained in more detail.

The coke oven gas a is compressed and subjected to a desulfurization stage 1 fed. After desulfurization, the coke oven gas is preheated. After admixture of water vapor that is generated in the waste heat boilers of a tube furnace 2, that Coke oven gas reacted catalytically in the tube furnace 2. The tube furnace 2 is expediently with coke oven gas d and solution and expansion gas c from the ammonia synthesis stage 6 underfired using combustion air t.

Blast furnace gas c is compressed and desulphurized before it is before the at f Conversion stage 3 is added to the cracked gas from the tube furnace 2. It is also possible, the furnace gas at f 'or f' ', i.e. before compression and desulfurization or upstream of the cracking furnace 2 to be supplied to the process. The supply of the furnace gas at f "would have the advantage that a separate desulfurization and the top gas compressor can be omitted.

The amount of furnace gas c is determined by the required hydrogen / nitrogen ratio certainly. The following process stages: conversion 3, CO2 scrubbing 4, methanation 5 are required here, as in conventional ammonia synthesis gas generation.

In the drawing, 6 also denote the ammonia synthesis stage, b the ammonia produced and g the CO2 exhaust gas.

The following example is based on the raw material coke oven gas and should make typical proportions and operating parameters clear.

Example: 1. Entry into the tube gap furnace (after desulfurization) analysis Coke oven gas substance Vol t (dry) Sulfur content 1 ppm CO2 0.62 CO 6.03 H2 63.48 25.75 C2H6 1.00 N2 3.12 100.00 Amount of gas: 1060 mn³ (dry) Water vapor addition: 2540.0 mn³ Coke oven gas temperature: 450 C Steam temperature: 4500 C Pressure of the reaction media: 24 bar 2nd outlet tube cracking furnace Analysis cracking gas substance Vol% (dry) CO2 8.35 CO 8.68 H2 80.65 CH4 0.53 N2 1.59 100.00 reaction pressure = 20.0 bar reaction temperature = 875.00 C amount of hot gas = 20 mn3 (dry) amount of water vapor 2100 mn³ 3. Mixture of cracked gas + furnace gas furnace gas analysis: substance Vol 8 (dry) pressure: 22 bar CO2 15.00 Temperature: 200 C (360 ° C) CO 25.00 H2 4.00 N2 56.00 - 100.00 Top gas quantity: 1450 m analysis according to mixture substance vol% dry CO2 10.74 CO 14.54 H2 53.26 CH4 0.34 N2 21.12 - 100.00 Amount of gas for converting 3210 into (dry) water vapor in the mixed gas for conversion Od # O mn3 4. Conversion convert gas analysis. Outlet low temperature conversion substance vol% (dry) pressure: 17 bar Co2 2i, 83 Temperature: 2400 C CO 0.30 H2 59.08 CH4 0.30 N2 18.49 100.00 Convert gas outlet 3670 m (dry) n Water vapor in the converting gas 1640 5. CO2 scrubbing Gas analysis outlet: Substance% by volume (dry) Pressure: 16 bar CO2 0.10 Temperature: 80 ° C CO 0.38 H2 75.00 CH4 0.38 N2 24.14 100.00 Purified gas outlet 2870 mn³ (dry) C03 waste gas: 800 m³ (dry) pressure: 1 bar abs temperature: 600 C 6. Synthesis gas (according to Methanation) Gas analysis: substance vol t (dry) pressure: 15.5 bar CO2 10 ppm CO ) * H2 74.70 CH4 0.87 N2 24.43 - 100.00 Synthesis gas quantity 2g30 (dry)

Claims (2)

"Process for the production of ammonia synthesis gas according to the steam reforming process" Claims: 1. Process for the production of ammonia synthesis gas from H2 -containing Input materials such as coke oven gas, natural gas, refinery gas, liquefied petroleum gas or naphtha the steam reforming process, characterized by the addition of blast furnace top gas as a nitrogen carrier. 2. The method according to claim 1, characterized in that the furnace gas is admixed with the process gas stream before the conversion.