Water-based heat transfer fluid cooling systems intrinsically safe from boiling liquid expanding vapor explosion (bleve)in various pyrometallurgical furnace applications

Abstract

A cooling system for use in support of a pyro-metallurgical furnace includes a liquid heat transfer fluid blend of 10%-50% water with monoethylene glycol (MEG), diethylene glycol (DEG), or triethylene glycol (TEG), and corrosion inhibitors. When using such glycols, a minimum of 10% water prevents the heat transfer fluid from becoming too viscous for economical pumping, and a maximum of 50% water prevents BLEVE incidents inside the furnace. Such intrinsically safe cooling system circulates the liquid heat transfer fluid blend with an optimally sized pump, filtration, pressurization, and at flow velocities sufficient to avoid film boiling.

1 . A water-based heat transfer fluid cooled system that is intrinsically safe from BLEVE when used in a pyro-metallurgical furnace, comprising:
 at least one water-cooled appliance comprising a vertical lance, a subsonic top submerged lance (TSL), a sonic lance, a torch, a tuyere, and a burner block, as are variously included in both ferrous and nonferrous pyro-metallurgical furnaces;   a coolant circulation network disposed in, jacketed around, or embedded within the water-cooled appliance of the furnace and providing for intrinsically safe liquid cooling of the appliance;   a coolant comprising a blended mixture of a single phase organic compound of glycol alcohol, water, and a corrosion inhibitor, wherein the water is limited to a range of about 10% to 50% of the total by weight, and wherein all of the water is fully absorbed in the glycol alcohol; and   a pump with a particular critically sized minimum capacity dependent on the viscosity and specific heat of the coolant and that circulates the coolant through the coolant circulation network at a predetermined minimum volume and velocity to preclude film boiling;   wherein, the coolant continually physically absorbs the water and desiccates the interior passages of the coolant circulation network such that a leak of the coolant into the pyro-metallurgical furnace cannot cause a BLEVE with free water.   
     
     
         2 . The water-based heat transfer fluid cooled system of  claim 1 , wherein the appliance comprises a subsonic top submerged lance (TSL) subject to wear and bending that can be caused by the inadequate or uneven cooling conventionally provided by an oxidizing gas flow down into a nonferrous pyro-metallurgical furnace, and wherein the circulation of the coolant through a jacket surrounding the TSL precludes such wear and bending safe from BLEVE caused by leaks of coolant. 
     
     
         3 . The water-based heat transfer fluid cooled system of  claim 1 , wherein the coolant has a predetermined specific heat greater than 2.3 kJ/kg·K, a predetermined viscosity of less than 20 mPa·s, and the glycol alcohol is one of monoethylene glycol (MEG), diethylene glycol (DEG), and propylene glycol (PEG). 
     
     
         4 . An oxidizing gas injection system for a pyro-metallurgical furnace, comprising:
 an oxidizing gas injector for a pyro-metallurgical furnace;   a cooling jacking disposed outside, around and along the full length of the oxidizing gas injector;   a heat transfer fluid mixture comprising water, corrosion inhibitors, and glycol, and that combined has a predetermined specific heat greater than 2.3 kJ/kg·K, and a predetermined viscosity of less than 20 mPa·s, and wherein, the heat transfer fluid mixture is intrinsically incapable of a boiling liquid expanding vapor explosion (BLEVE);   a liquid pumping system that circulates the heat transfer fluid mixture through the cooling jacking and that maintains a minimum fluid velocity at predetermined points within the cooling jacket to prevent film boiling of the heat transfer fluid mixture;   a coolant pressurization system connected to contain the heat transfer fluid mixture and raise its boiling point;   a filter connected to remove contaminants from the heat transfer fluid mixture; and   a heat exchanger connected to remove and dispose of heat from the heat transfer fluid mixture.   
     
     
         5 . A gas injection system for a pyro-metallurgical furnace, comprising:
 a heat transfer fluid mixture of water, corrosion inhibitors, and monoethylene glycol (MEG), and having in combination simultaneous predetermined limits on viscosity and specific heat;   wherein, the heat transfer fluid mixture is intrinsically incapable of a boiling liquid expanding vapor explosion (BLEVE);   a cooling system that extracts and disposes of heat from the heat transfer fluid mixture and that provides liquid pumping for minimum circulation velocities that preclude film boiling of the heat transfer fluid mixture; and   a gas injection lance with a liquid cooled jacket that extends the full length to a lance tip, and that receives the heat transfer fluid mixture from the cooling system, and that returns heated heat transfer fluid mixture, and that thwarts thermal curving of the gas injection lance by precluding uneven heating of it during operation;   wherein, the liquid cooled jacket maintains a minimum velocity of the heat transfer fluid mixture within at any particular point to prevent film boiling; and   wherein, the gas injection lance includes a conduit for the injection of a gas flow into a ferrous or nonferrous pyro-metallurgical furnace.   
     
     
         6 . The gas injection system of  claim 5 , wherein the heat transfer fluid mixture has a predetermined viscosity of less than 20 mPa·s. 
     
     
         7 . The oxygen injection system of  claim 5 , wherein the heat transfer fluid mixture has a predetermined specific heat greater than 2.3 kJ/kg·K. 
     
     
         8 . The gas injection system of  claim 5 , wherein the liquid cooled jacket maintains even temperatures that prevent curving of the lance with an inclusion of swirlers, and maintains said minimum velocity flow of 2.0 meters per second of the heat transfer fluid mixture within at least the gas injection lance tip to prevent film boiling. 
     
     
         9 . The gas injection system of  claim 8  wherein the solid feed to the furnace is fed down inside the gas injection lance and directly into the bath to reduce a loss of feed to a rush of off-gas.