Calculation problems for steam jet pumps
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Calculate a jet pump problem in which 3 kg of steam at gauge pressure is used to absorb nitrogen at atmospheric pressure and send it into an incinerator, with a small amount of exhaust gas that is negligible due to its low volume. Following the steps outlined in SH/T 3118-2000, the compression ratio is found to be 1.12 and the expansion ratio to be 4.1. It is therefore impossible to initially determine the injection coefficient or the steam calculation coefficient for the nozzle, as the minimum expansion ratio specified in this standard is 10, and the minimum compression ratio is 1.4. What should be done in such a situation? Or what calculation method should be used? The steam jet pump released in 1974 seems not to be very suitable either; it is designed for cooling purposes.
I have examined the SH/T3118-2000 standard, the vacuum design manual, and the unit manual, but none of them allow for calculating this situation. Only the books on jet calculators from the former Soviet Union mention this, but the theory presented in them is too complex; the examples given deal with interactions within the same medium, and there is no mention of interactions between air and steam. . Could there be an **explanation? . .
These are special types of injectors; based on your parameters, 3.0 barG is required to extract exhaust gas (air at 30°C) at a rate of 0.3 t/h, 0.98 bar abs for a flow rate of 1 t/h, and 1.1 bar abs for exhaust gas expulsion. Under a few tons, it’s a very, very small injector! At 1 t/h, it requires a DN50 injector.