Abstract: An apparatus for metering an accurate flow of a first fluid, at a low pressure and a low flow rate, into a conduit conducting a flow of a second fluid, at a much higher pressure and much greater flow rate, comprises a pressure reducer containing a nozzle and a peristaltic pump connected in fluid communication with the pressure reducer. The pressure reducer is connected in the conduit and the nozzle of the pressure reducer increases the flow rate of the second fluid flowing through the pressure reducer, thereby correspondingly reducing the pressure of the second fluid in the pressure reducer. The peristaltic pump supplies the first fluid to an area of the bore through the pressure reducer where the nozzle has decreased the pressure of the second fluid channeled through the pressure reducer. A pressure relief valve communicates with the pressure reducer to prevent the pressure of the second fluid from decreasing below a third fluid pressure.

Abstract: Energy conserving limestone calcining system, including a process and apparatus in which in a first step or kiln zone limestone is heated, e.g., at 1700.degree.-2100.degree. F., sufficiently to achieve more than only about 50 or 60%, e.g.