(22)  Robson's  Gas  Producer.  Patent  No.  25560  of  1902.—
This  producer  is  shown  in  Fig.  22.  Around  the  lower  portion
of  the  coal-feeding  hopper  6  is  cast  an  air  jacket  13  to  which
a  fan  14  is  connected  by  duct  15.  The  jacket  13  is  also
intersected  by  four  air  pipes  16.  The  outside  ends  of  the
pipes  are  connected  to  the  top  of  an  inner  vertical  annular
casing  3 — 4.  Four  oblong  apertures  19  are  cut  below  the
air  pipes,  which  permit  the  hot  gases  from  the  producer  fire
to  pass  into  the  cover.  To  the  bottom  of  each  pipe  is
attached  a  small  dish  18.  A  little  water  is  kept  dropping
into  each  dish,  and  is  vaporised  by  the  hot  gases  in  which
they  are  enveloped.  The  air  from  the  fan  is  first  heated  in
the  coal  hopper,  and  becomes  mixed  with  the  steam  as  it
passes  out  of  the  dishes,  and  it  drives  this  forward  into  the
inner  casing  3 — 4,  where  it  is  further  heated.  From  the
bottom  of  the  casing  it  enters  two  pipes  25  which  are  connected


APPENDIX.
at  opposite  sides  to  a  circular  passage  23  round  the  interior
of  a  cast-iron  ring  grate  21  which  carries  the  firebars  22.
Having  received  additional  heat  from  the  grate,  the  air  and
vapour  now  pass  out  by  two  segmental  slots  24  through  the
metal  on  the  inside  of  the  ring  and  on  opposite  sides  just
b3low  the  firebars.  These  firebars  run  longitudinally  to  the
air  slots,  so  that  the  air  and  steam  will  pass  up  into  the  fire
from  between  the  ends  of  the  bars.  The  steam  and  hot  air
now  enter  the  shaft  26,  which  is  encircled  by  a  firebrick
lining  27.  Having  passed  through  the  fire,  the  gas  now


FIQ.  I.
