Northern Combustion Systems has a wealth of experience and knowledge in the design, manufacture and install of quenching systems , including civil works.
Optimal quench uniformity is essential if the potential for cracking, distortion, residual stress and spotty hardness is to be minimized. Cooling must be as uniform as possible throughout the quenching process.
Agitation is one of the most critical areas of system design. The quenching performance of a liquid quenchant can be controlled by controlling the agitation in the quench tank. Without agitation, a vapor layer or bubbles form at the hot part surface and the natural convention of the quenchant limit the heat extraction rate at the quenched part surface. Resistance to the heat extraction rate can be reduced by breaking the vapor layer or by inducing a turbulent convection at the part surface through agitation (i.e. forced circulation of the quenchant). This is achieved by placing a network of piping within the tank, on the walls and floor with jet nozzles directed at the parts surface.
External to the tanks are several pumps of various sizes specified on the size and volume of the tank and the agitation required. This could range from 1 x 22kw pump on our smaller tanks, and 4 x 55kw pumps on our larger tanks. All our pumps are controlled by variable frequency drives (VFD) to control the amount of agitation within the tank.
Another critical area of the design is water temperature. It is crucial to keep the quenchant temperature as low as possible after the part has been submerged, this is a key factor when calculating the tanks volume and is based on the temperature and mass of the part to be quenched and the frequency of quenches.
If the system is going to be used frequently and rapid cooling of the quenchant is required, then a cooling system will be added. Quenchant temperature will be monitored by temperature sensors, when the temperature raise’s above a pre-defined setpoint, quenchant will be drawn from the top of the tank and pumped through a cooling system and returned to the bottom of the tank. Various types of cooling systems, including Adiabatic coolers, Tower coolers and closed loop heat exchangers will be used depending on the rate at which cooling is required and the tank volume.