What Is a Jacket Reactor? Heat Transfer & Applications

Answering the core question: What is a jacket reactor, and how does its heat-transfer jacket govern reaction temperature? A jacket reactor is defined by the annular or coil subsystem surrounding the vessel shell that circulates heating or cooling fluid to set the wall temperature within plus or minus 0.5-2 degree C. Jacket design determines the overall coefficient U (50 W/m2K plain up to 500 W/m2K half-pipe coil) and the log-mean temperature difference (LMTD) that drives heat flux of 5-50 kW/m2. Matching fluid velocity above 1.5 m/s and turbulence keeps U high while limiting pressure drop, enabling exothermic control from minus 40 degree C glycol cooling to 350 degree C thermal-oil heating at 0.1-10 MPa.

• **LMTD and Heat Flux:** Q = U times A times LMTD; a 20 degree C LMTD with U=300 W/m2K yields 6 kW/m2, sizing jackets for 50-200 kW per m3 batch.
• **Fluid Velocity and Turbulence:** Velocity above 1.5 m/s in half-pipe coils induces turbulent film (Re above 10,000), lifting U and reducing fouling versus laminar flow.
• **Cascade Temperature Control:** Jacket supply/return sensors modulate a control valve on the thermal-fluid skid to hold reactor setpoint within plus or minus 0.5 degree C.

• **Dimple Jacket:** Laser-welded dimples create turbulent film at 0.3-1.0 MPa; economical for 0.5-20 m3 tanks.
• **Half-Pipe Coil:** 180 degree pipe sections at 2-6 MPa; highest U (300-500 W/m2K) for severe exotherms.
• **Limpet or External Coil:** Twin serpentine coils on large 50-200 m3 reactors where full jacketing is structurally costly.

A: The terms overlap; a jacket reactor emphasizes the heat-transfer subsystem (coil/dimple/LMTD), while jacketed reactor refers to the whole vessel equipped with that jacket.

A: Higher fluid velocity (above 1.5 m/s) and turbulent dimples or coils raise U from 50 to 500 W/m2K, increasing removable heat per unit area.

A: Thermal oil serves 200-350 degree C; water-glycol covers minus 40 to 120 degree C; steam heats to 200 degree C, so combined loops span minus 40 to 350 degree C.

A: Dual sensing enables cascade control that anticipates load changes, holding the reactor within plus or minus 0.5 degree C even during fast exotherms.

Tags: Stainless Steel Reactor, Chemical Reactor System, Industrial Chemical Reactor