Tank Heating by Various Methods for Metal Finishing and Other Process Heating Applications OVERVIEW 1

Industries Using Process Tanks Metal Processing & Finishings  Plating (Chrome, Brass, Precious Metals)  Anodizing  Galvanizing  Phosphatizing  Spray Wash Systems  Pickling  Quenching 2

Food Processing  Hot Oil Anodizing  Corn Cooking (tortilla chip manufacturing)  Food preparation in Jacketed Kettles (open tanks)  Dairy (vat type milk pasteurizing, cheese processing, CIP systems)  Juice pasteurizing (typically with plate & frame heat exchanger)  Breweries (craft, micro breweries)  Food Plant Cleanup  Egg Processing (egg washing)  Poultry Processing (scalding tanks) 3

Miscellaneous  Cosmetics Manufacturing  Aloe Vera Processing 4

Common Sources For Process Tank Heat  Direct Firing (through large diameter tube in tank) Electric Immersion Heaters  Steam (through heat exchange coils)  Hot Water (through heat exchange coils) 5

Heating Methods 6 Direct Gas Firing Typically through a welded steel fire tube along the inside lower portion of tank Steam Through heat exchange coils or panels immersed in tanks Hot Water Closed Loop Recirculating Through heat exchange coils or panels immersed in tanks Heaters Immersed in Tanks Electric Immersion Heater

Electric Immersion Heater ADVANTAGES & DISAVANTAGES ADVANTAGES  Efficient method of heating  Heaters take up small space in tank DISADVANTAGES  High cost of electric power(in most areas)  High voltage power at tanks  Potential fire hazard  Heaters fail, need to be replaced periodically  Potentially high temperatures at heater – could damage some baths 7

Direct Gas Firing ADVANTAGES & DISADVANTAGES 8 ADVANTAGES  Moderate cost for single tank installation DISADVANTAGES  Requires separate burner system for each tank  Can be inefficient due to limitations of tube surface area – typically only 60% to 70% efficient  Not suitable for use in polypropylene tanks  Potential fire hazard  Low NOx burners not available

Steam ADVANTAGES & DISADVANTAGES 9 ADVANTAGES  Highly efficient method of heat transfer - (better that the two methods listed above) -  Heat exchange coils can be located along side(s), end(s), or bottom of tank DISADVANTAGES  Typically a central boiler with piping to all heated tanks – (this could be viewed as an advantage)  Steam boiler requires soft water, boiler water treatment, blowdown – periodic internal inspections, maintenance  Some jurisdictions require boiler operating permit, attendant, licensing  Higher capital cost

Hot Water – Closed Loop Recirculating ADVANTAGES & DISAVANTAGES 10 ADVANTAGES  Normally this is the best choice of all listed heating methods  Highly efficient method of heat transfer – Parker offers Hot Water Boilers with up to 86% efficiency  Heat exchange coils can be located along side(s), end(s), or bottom of tank  Low system maintenance cost compared to steam – closed system means no water makeup or continual water treatment or blowdown  Typically no boiler attendant required DISADVANTAGES  Typically a central boiler with piping to all heated tanks – (this could be viewed as an advantage)  Tank temperature may be limited by maximum outlet temperature of some boilers (not a problem for Parker Hot Water Boilers, as we can run as high as 350°F without sacrificing long service life)  Higher capital cost

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Brief Description of the Electroplating Process  Items to be plated are immersed in a “bath” (a tank containing chemicals to enhance the plating process, and amounts of the material of plating). A Direct Current is applied to the target items and the plating material, which causes the plating material to migrate to the item to be plated. 12

Some Common Terms Used in the Metal Finishing Process:  Immersion Heaters – electric heat source  Immersion Coils – (may be pipe or panel coils) steam or hot water  Bath – The contents of the liquid in the tank, including the chemicals used.  Bath Depth – The depth of the liquid in the tank  Bath Temperature – The ideal temperature of the bath to accomplish the plating process  Working Depth – The effective depth of the usable part of the tank  Freeboard – The empty space between the bath surface and the top of the tank  Rectifier – A device which converts AC power to DC power for use in the plating process 13

Typical Tank Configurations  Most common are rectangular, open top  Sometimes “utility” or “mother” tanks are used – these may be remote from the process stank, and typically contain heat exchanger, filtration system, etc. 14

Figuring The Heating Load OVERVIEW 15

Tank Heat Losses  Bath surface area  Tank sidewalls  Agitation (air, mechanical)  Fume hoods  Product throughput  Makeup water / overflow to/from tank 16

Heating System Sizing & Selection  Length of time desirable / allowable for system heat-up from cold start. This is critical, as it determines the size of the entire heating system. For smaller systems, 3 to 4 hours is typical. For larger systems, 8 to 10 hours may be more practical. These times are guidelines – final decision should be based on an informed customers decision.  Output temperature of heating system must be high enough to provide “thermal drive” to heat highest tank temperatures in the system.  If heat source is steam, be sure that any condensate lift requirements can be handled by steam pressure, otherwise a condensate lift station may be required.  If heat source is hot water, be sure velocity flow is within design parameters and pressure drop through coils is within capability of system pump. 17

Heating Coil Sizing & Selection  Must be of adequate heating surface to handle tank heating load per calculations  Must be rated for temperature and pressure of heating system –  Coil material selection must be compatible with bath chemistry and approved by customer for appropriate resistance to corrosion. 18

We At Parker Boiler Company Make It Easy To Figure The System Heat Load And To Select The Appropriate Equipment With These 3 Steps:  - Get the appropriate tank data from customer per our TANK DATA WORKSHEET  - Plug that data into our SPREADSHEET  - Size and price the proper Parker System 19

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Sample Plating Job 21

High Temp. Hot Water System Single Boiler / Single Pump Diagram 22

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