North American Snow Melters with Immersion Burners
Sheet 4762-2
Snow can be disposed of quickly by pushing it into a pit contain- ing water heated by a 4762 Hi-Capacity Immersion Burner. The warm water melts the snow very rapidly and the resulting excess water runs down a sewer. A complete system is particularly benificial for (1) areas which must be quickly cleared for parking after snowfalls, (2) businesses which cannot wait for commercial trucking firms or city trucks to haul away collected snow, or (3) confined areas where there is no place to pile snow. The time saved by having a guickly cleared parking area can mean money in the pocket to owners of parking lots, funeral homes, supermarkets, and used-car lots. Cost comparisons with trucking charges for hauling snow will often indicate more cash savings. Design Assumptions. These pages suggest an approach to de- sign and selection of burner equipment for a snow melting pit. It is based on 6"w.c. natural gas pressure and 8 osi combustion air pressure. Equipment selected should be modified for other gases or pressures, larger or smaller melting pits, or more or less snow to be cleared. Bulletin 4762 gives details on burner selection. Melting pit dimensions should be studied for each local con- dition and intended use. If the cover must carry the weight of automobiles, the pits are made long and narrow.
Some pits contain a large reservoir of water for more melting capacity once snow is started into pit. Others contain a minimum of water so the melting operations can start immediately. Some pits are drained after every use. On others the water is allowed to freeze to avoid installing outdoor water supply pipes (which must be drained after every use). Snow melting calculations. Snow weighs one-tenth as much as the same volume of water. A 10" snow depth is equal in weight to 1" of water over the same area. (Water weighs 62.4 lb per cu ft.) Wet snow weighs more, but the additional weight is water and will not require heat for melting. The heat required to convert one pound of snow at 32°F is 144 Btu.
Btu/hr to melt = lb snow/hr × 144 Btu/lb = sq ft parking lot × ft snow depth × 62.4 × 0.10 × 144
Burner input for the tubes shown ordinarily should be based on 90% efficiency. Since it is not necessary to melt all of the snow (some is carried away as slush), assume burner output equals heat available for snow melting. Additional heat is required to raise the temperature of the snow from the ambient temperature to 32°F, but this is negligible com- pared to the heat for melting.
Table 1. RATINGS and CAPACITIES
Snow Melter Size
4762-4
4762-6 16,000
4762-8 42,000
Approximate area melted in 1 hr
8,000
with 2" snow fall, sq ft Water in snow pit, gallon Burner capacity, Btu/hr
520
1,120
3,200
620,000
1,200,000
2,800,000
Minimum natural gas pressure
6"wc 8 osi
6"wc 8 osi
6"wc 8 osi
Blower air pressure
“A”, pipe size air line “B”, pipe size gas line
2"
3" 2"
6" 3"
1¼"
Made with FlippingBook flipbook maker