Flow diagram for mixing nitrogen after hydrogen extraction from coke oven gas
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Dear colleagues, could you please provide a flow diagram for blending nitrogen with hydrogen extracted from coke oven gas? The nitrogen coming from air separation should be deoxygenated, right? Or is it deoxygenated after being mixed with other gases? Also, what’s the structure of the mixer? Thanks!
The nitrogen produced by air separation at 99.95% purity can be used directly. It mainly depends on how the preceding processes are organized; even minor variations in oxygen content can be accommodated prior to methanation. Catalysts can be used, but they’re not necessary even when the amount of oxygen is small.
With my PSA system, the hydrogen purity reaches 99.5%, and the nitrogen purity is 99.9%. After being mixed and compressed, it is directly used for synthesizing liquid ammonia, with no methanation occurring. There is no oxygen in hydrogen; there might be a small amount of oxygen in nitrogen. I would like to ask: 1. Are there specialized mixers for this purpose, such as mixers for mixing nitric acid with ammonia? 2. To minimize the harmful effects of oxygen on the synthesis, should nitrogen be used for deoxygenation alone or after mixing?
By the way, to the two people above: after mixing the hydrogen obtained via pressure swing adsorption with the nitrogen from air separation, is further desulfurization necessary? (Personally, I believe there’s no need for further desulfurization; in the initial stages of pressure swing adsorption for hydrogen purification, sulfur removal already takes place.) I would appreciate any guidance from everyone. . .
For 99.5% pure hydrogen, the contents of oxygen, carbon monoxide, and carbon dioxide must all be less than 0.1%; in particular, the levels of these two carbon-containing substances must be below a few dozen PPm. For 99.9% pure nitrogen, no deoxidation is required; it can be directly mixed with other gases. Desulfurization should be completed prior to the PSA process, as PSA units are also sensitive to sulfur
Desulfurization has already been carried out in the early stage; no further desulfurization is needed later. You can also ask the designer.
Initially, the sulfur content in the hydrogen produced by the PSA hydrogen generation unit was ≤1 ppm; meanwhile, the sulfur content in imported hydrogen is ≤0.1 ppm. I would like to ask experts here: Is this also the case in actual production or design?
Initially, the sulfur content in the hydrogen produced by the PSA hydrogen generation unit was ≤1 ppm; meanwhile, the sulfur content in imported hydrogen is ≤0.1 ppm. I would like to ask experts here: Is this also the case in actual production or design?
In actual production, the sulfur content resulting from the Rectisolve process is already <0.1 ppm
Yes, when designing our PSA, we require the inlet gas to be ≤10mg/Nm³ (about 6ppm), and the PSA outlet can guarantee ≤0.1ppm, which is equivalent to being desulfurized, while the synthetic imported sulfur content must be <0.1ppm. Sulfur will permanently poison the synthetic catalyst.