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A-Type :
A-type watertube boilers represent an alternate way designing watertube boilers. It is symmetrical, well balanced boiler with a large furnace volume.
The A-type design such as Thermoboil A-type boiler provides a larger furnace than an O-type design for example and will offer the same advantages than the O-type as far as symmetry and natural circulation are concerned. It will go as high in capacity, pressure and temperature than an O-type but will be bigger and cost more money since it is bigger and has an extra mud drum. Capacities for package units can go as high as 250,000 lbs/hr (115 tons/hr) with pressures up to 1500psig (103 bar) and temperatures up to 1000F (537C).Higher capacities are possible with field erected units.
It is very appropriate to fire no.6 oil, no.2 oil or gas .It is also available with an open bottom furnace to allow burning of solid fuels such as wood residues, agricultural wastes, bagasse etc. A D-type or an O-type boiler is not as suitable for solid fuel burning due to its geometry.
Radiant and convective type superheaters can be added at the rear end of the A-type Thermoboil units and provide superheated steam at a constant temperature over all the firing range. For very large capacities, high pressures and temperatures, it is often the choice of the consulting engineers and of the end users. The design can be built with membrane waterwalls or with tangent tubes. In most cases membrane waterwalls are preferred.
It can perform as well as a D-type but will cost a little bit more to produce. A-type boilers are often using for cogeneration, petrochemical industries, industrial processes etc. It is a rugged and conservative design. On large sizes the furnace gas pressures are much lower than a D-type or an O-type due to the boiler bank configurations and the burners will require less fan power.
It is a well balanced boiler design. It will be easier to ship by road or by train than
D-types because of its A-type shape, which fits better with tunnels and bridges.

Capacities:From 20,000 lbs/hr (10 tons/hr) to
 250,000 lbs/hr (115 tons/hr) with or without superheater

Pressures:250 psig (17 bars) design up to 1500 psig (100 bars)
Superheaters: Temperature up to 950 F (510 C)
Fuels:Oil, gas or combination, or solid fuels
-Membrane or tangent tube wall construction to ASME code section I
-Optional water cooled membrane rear wall
-Optional water cooled membrane front wall and burner throat
-Open bottom furnace available for solid fuel firing
-Steam purity up to 1 ppm

Phisical Data "A" Type Boilers:

Side Elevation Front View

Boiler
model number
Capacity
tons/hr
-A-
Length

mm
-B-
Width

mm
-C-
Height

mm
-D-
Base width

mm
-E- -F-
Gas outlet mm
Width Length
Weights
(In kg)
Dry Flooded
A1-20 9.0 4500 3685 3810 2615 2135 610 29500 36500
A1-30 13.5 5410 3685 3810 2615 2135 610 31500 41000
A1-40 18.0 6100 3685 3810 2615 2135 610 34000 45500
A1-50 22.5 6830 3685 3810 2615 2135 610 38500 50000
A2-60 27.0 7035 3785 4215 2870 2385 810 43000 59000
A2-70 32.0 7550 3785 4215 2870 2385 810 45500 61000
A2-80 36.5 7925 3785 4215 2870 2385 810 47500 66000
A2-90 41.0 8460 3785 4215 2870 2385 915 50000 68000
A3-100 45.5 10060 3885 4725 2870 2385 1220 59000 79500
A3-110 50.0 10600 3885 4725 2870 2385 1220 61500 82000
A3-125 57.0 11500 3885 4725 2870 2385 1320 66000 88500
A3-150 68.0 12500 3885 4725 2870 2385 1320 68000 95000
A4-175 79.5 12930 3935 5080 2920 2385 1830 75000 109000
A4-200 91.0 13550 3935 5080 2920 2385 1830 79500 113500
A4-250 113.5 15170 3935 5080 2920 2385 1830 86000 125000
*All dimensions are metric

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