Measurement of x-ray absorption in fluid streams

An X-ray absorption measuring apparatus for monitoring a fluid stream comprises a metal block having a passageway 23 for the fluid and upper and lower chambers which communicate with the passageway, the upper chamber accommodating a window 16 behind which a bolt 11 supports a monochromatic X-ray source 12 and the lower chamber accommodating a window 26 behind which a member 21 supports a Geiger tube 18, the bolt 11 and the member 21 each being arranged to engage and secure in position the associated window, suitable gaskets 24 and 25 being interposed for sealing purposes. The X-ray source comprises Fe55 which is plated on a small piece of platinum which is fastened to bolt 11. The windows are made of beryllium and the block is formed of stainless steel or other corrosion resistant material. The output of the Geiger tube may be applied to a counter circuit the result from which may be presented periodically by a printer. For high count rates a rate meter may be provided. For low count rates, a timer may be provided to record the time necessary to reach a predetermined count. In one application of the invention, Fig. 3, the apparatus is employed to monitor the sulphur concentration in the output of a hydrofining process in which kerosene, gas oil residue or lube stocks supplied via line 101 together with hydrogen via line 103 is preheated in a furnace 102 by combustion of natural gas supplied via line 119 and then supplied to a reaction chamber 105 maintained at 550 DEG -800 DEG F. and 150-800 p.s.i.g., containing a cobalt molybdate on alumina catalyst. The reactor effluent is withdrawn via line 106 and passed via a cooler 107 to a separator 108 from which gas and liquid are withdrawn via lines 110 and 111 respectively. The gas is either released or recycled to a scrubber system to remove hydrogen sulphide and then supplied back to reactor 105. The liquid is passed to a low pressure separator, which removes remaining residual gas, the liquid from the bottoms being passed via pump 123 to storage. In applying the apparatus of the invention, a portion of either the gas or liquid output is passed via an X-ray monitor apparatus 112, 125 to determine the sulphur content. The monitor may provide an electric or pneumatic signal 120, 128, which actuates a mechanism 113 to regulate the furnace firing rate by adjusting a valve 127 in fuel line 119.ALSO: An X-ray absorption measuring