Scraped surface heat exchanger CHE500

liquid/liquidstainless steelfor the food industry

Overview
The CHE500 scraped-surface heat exchanger conditions viscous confectionery masses in continuous flow. It is manufactured for a single thermal duty chosen at order: either reheating tempered-chocolate return streams or cooling cooked caramel prior to depositing. Heating versions use glass-wool insulation; cooling versions use CFC-free rubber insulation. Each unit is built and validated for one duty only.

Process suitability

• Not recommended when the product is low-viscosity and a smooth-wall jacketed exchanger provides sufficient heat transfer.
• Not suitable when simultaneous heating and cooling are required from the same unit; select one duty per installation.
• Does not replace a tempering machine: it melts residual stable crystals on a return stream but does not create the tempered crystal structure (Form V).
• Heating configuration requires a continuous bypass return; not applicable for batch wheel temperers without continuous return flow.
• Requires three-phase power (380 V); standard installed electrical power 4 kW.

Thermal duty (select at order)
Heating — tempered chocolate return
Glass-wool insulation. Typical capacity up to 1000 kg/h. Supply hot water at about 50–55 °C to the stator jacket and the hollow rotor. The unit raises the return-stream temperature and melts residual stable crystals before the chocolate returns to the holding tank. Product outlet temperature is the control variable. Actual throughput depends on chocolate inlet/outlet temperatures, viscosity, hot-water flow and rotor speed.

Cooling — cooked caramel
CFC-free rubber insulation. Typical capacity up to 400 kg/h. Supply chilled water from an external chiller to the stator jacket and rotor core. The unit lowers continuously flowing cooked caramel to the specified depositing or filling temperature. If the required outlet temperature cannot be reached at the selected flow, additional holding or cooling is necessary. Throughput depends on caramel inlet/outlet temperatures, viscosity, chilled-water temperature and flow, and rotor speed.

CHE500 vs smooth-wall jacketed pipe
Decision — Scraped-surface exchanger — Smooth-wall jacketed pipe
Viscous or fouling-prone product — Scrapers continually renew the wall film — Heat-transfer performance can decline as the boundary layer develops
Fouling risk — Reduced (operating conditions still matter) — Higher for viscous, sticky or crystallizing products
Low-viscosity clean stream — Eliminate the scraped-surface exchanger — Usually the simpler selection
High-viscosity chocolate or caramel — Select after thermal-duty verification — Use only if validated for the required duty

How scraped-surface heat transfer works
Viscous chocolate or caramel forms a slow-moving film at the heated or cooled wall, increasing thermal resistance. The CHE500 helix rotor carries PTFE scrapers that continuously sweep the stator wall and renew the film with product from the main flow. Hot or chilled water also passes through the hollow rotor, providing a second heat-transfer surface inside the product path.

Position in the production line
Heating configuration
Install on the bypass return branch between the heated diverter valve at the continuous tempering-machine outlet and the chocolate storage tank. The unit reheats the return stream only when the diverter sends chocolate through the return leg; keep the unit close to the valve to minimise cooling in pipe runs.

Cooling configuration
Install directly after the caramel cooker and ahead of the storage tank that feeds the depositor; the cooker normally discharges directly into the exchanger in this configuration.

Maintenance, Cleaning, and Warranty

• Water circuit treatment: keep stator jacket and rotor-core circuit treated against scale; untreated water forms scale and reduces thermal performance.
• PTFE scrapers: inspect for wear, damage and effective wall contact during scheduled maintenance; replacement frequency depends on product abrasiveness, rotor speed and operating hours.
• Rotary joint: check for leakage on the preventive maintenance schedule; failed seals can let jacket water into the product path or starve the rotor core.
• Cleaning at product changes or before extended shutdown: for chocolate duty, run plain chocolate or cocoa butter through the tube to flush previous product; never flush a chocolate stream with water. For caramel duty, flush with hot water according to the filling’s cleaning requirements.
• Warranty and lead time: one-year warranty against manufacturing and construction defects. Lead time 3–4 months from order because each unit is built for the selected duty.

Technical specifications

• Model: CHE500
• Product-contact material: AISI 304
• Helix rotor with PTFE scrapers
• Adjustable rotor speed
• Water-jacketed stator
• Hollow water-conditioned rotor
• Rotary water joint (feeds hot or chilled water to rotating rotor)
• Cold-start protection
• Installed electrical power: 4 kW, 380 V three-phase
• Thermal duty: selectable at order — heating or cooling (unit built for one duty only)
• Heating capacity (typical): up to 1000 kg/h (depends on inlet/outlet temps, viscosity, rotor speed, water flow)
• Cooling capacity (typical): up to 400 kg/h (depends on inlet/outlet temps, viscosity, rotor speed, water flow)
• Insulation: glass-wool for heating units; CFC-free rubber for cooling units
• Lead time: 3–4 months from order
• Warranty: 1 year against manufacturing and construction defects