UNISCRUB™ Packed Tower Scrubber

Monday, 10 August 2009 13:44

UNISCRUB Packed Tower Scrubber

Reduced Height Packaged Neutralization Odor Control System

The Bay Products UniScrub packed tower chemical scrubber is efficient hydrogen sulfide or ammonia gas removal system. The system’s prime feature is its reduced height and common unified skid design. These systems are ideal were height is a concern or a packaged system is needed.

The system comes factory preassembled and mechanically tested with all pumps (chemical and recirculation), controls, piping and instrumentation all come on the common skid. The system is rectangular in design with two or three stage arrangement. Each stage has an independent sump that allows complete control of the process and chemical usage. The systems are made of UV resistant High Density Polyethylene (HDPE) or Fiberglass Reinforced Plastic (FRP).

Process Description

Foul air is pulled through the fiberglass corrosion resistant fan and blown through interconnecting ductwork through a flexible connector and into the bottom of the inlet plenum of stage-1 fiberglass reaction chamber. The chamber is filled packing material. Air flows countercurrent to a water solution delivered from sump-1 by a recirculation pump through overhead spray nozzles. The water solution contains sodium hydroxide that reacts with the hydrogen sulfide in the air stream. Additional sodium hydroxide is added by a chemical feed pump to the stage 1 water solution as required by a pH probe and pH controller. Treated air flows downward through a transfer channel to the bottom of stage-2. Air flows countercurrent to a water solution delivered from sump-2 by a recirculation pump through overhead spray nozzles. The water solution contains sodium hydroxide that reacts with the hydrogen sulfide in the air stream. Additional sodium hydroxide is added by a chemical feed pump to the stage 2 water solution as required by a pH probe and pH controller. Treated air flows downward through a transfer channel to the bottom of stage-3. The chamber is filled packing material. Air flows countercurrent to a water solution delivered from sump-3 by the third recirculation pump through overhead spray nozzles. The water solution contains sodium hydroxide and sodium hypochlorite that reacts with the hydrogen sulfide in the air stream. Additional sodium hydroxide and sodium hypochlorite is added by chemical feed pumps to the stage 3 water solution as required by a pH and ORP probe and pH and ORP controller respectively. The air leaves stage 3 and passes through a mist pad to remove any water droplets and passes out through the exhaust stack. Make up water is added to each sump as required to prevent byproduct build up. A control panel controls the chemical feed, fan, recirculation pumps, heaters, and level switches.

Since the system has three independent stages it can be configured to have the first stage operate for optimal ammonia removal by using acid feed. The other two stages can then operate as described above for maximum hydrogen sulfide removal. This provides complete ammonia and hydrogen sulfide removal in a single system.

Sample Process Flow Diagram

UNISCRUB diagram

Standard System Sizes

MODEL	AIR FLOW (CFM)	SCRUBBER DIMENSIONS L x W x H	OVERALL LENGTH	SHIPPING WEIGHT	OPERATING WEIGHT	FAN MOTOR (HP)¹	RECIRC. PUMP (HP)²
UNISCRUB 1000	1,000	5.5' x 5.0' x 8.5'	10.0'	1,200 lbs	3,500 lbs	5.0	1.5
UNISCRUB 1300	1,300	6.25' x 5.25 x 9.25'	11.0'	1,300 lbs	4,500 lbs	5.0	2.0
UNISCRUB 1700	1,700	7.0' x 5.5' x 9.25'	12.0'	2,400 lbs	6,000 lbs	7.5	2.0
UNISCRUB 2200	2,200	7.75' x 5.75' x 9.25'	13.5'	2,700 lbs	7,000 lbs	7.5	3.0
UNISCRUB 2700	2,700	8.5' x 6.0' x 9.5'	14.0'	3,400 lbs	8,000 lbs	7.5	3.0
UNISCRUB 3300	3,300	9.25' x 6.25' x 9.5'	16.0'	4,000 lbs	9,500 lbs	7.5	5.0
UNISCRUB 4000	4,000	10.0' x 6.5' x 10.5'	16.5'	4,800 lbs	11,000 lbs	10.0	5.0
UNISCRUB 5500	5,500	9.75' x 7.0' x 11.0'	17.0'	5,500 lbs	12,000 lbs	15.0	5.0
UNISCRUB 7100	7,100	11.0' x 7.5' x 11.0'	18.5'	6,300 lbs	14,500 lbs	15.0	5.0
UNISCRUB 9100	9,100	12.25' x 8.0' x 11.25'	20.50'	7,000 lbs	17,000 lbs	20.0	5.0
UNISCRUB 11200	11,200	13.2' x 8.5' x 11.5'	21.5'	7,600 lbs	19,500 lbs	25.0	7.5
UNISCRUB 13600	13,600	14.75' x 9.0' x 11.75'	23.0'	8,300 lbs	22,000 lbs	30.0	7.5
UNISCRUB 16200	16,200	16.0' x 9.5' x 12.0'	24.0'	9,000 lbs	25,500 lbs	40.0	7.5
UNISCRUB 20000	20,000	17.25' x 10.0' x 12.25'	27.0'	10,000 lbs	28,500 lbs	50.0	10.0
UNISCRUB 24500	24,500	18.5' x 10.5' x 12.5'	28.0'	11,000 lbs	32,000 lbs	60.0	10.0

¹ Fan based on 2" water column inlet duct loss
² Recirculation Pump horsepower is for each of three pumps required

Stack Height is minimum of 5'

Process Description

High velocity contaminated odorous gas enters the large plenum chamber wherein the velocity is reduced to provide even gas distribution across the bottom of the packing section.
The gas flows slowly through a bed of specifically selected packing, which creates a tortuous labyrinth that causes the gas to be completely mixed and reacted with the caustic solution. The counter current flow of gas and solution maintains an absorption driving force throughout the entire depth of the packing bed.
Fresh make-up solution is added to the solution being recirculated to compensate for evaporation and to keep the absorbed contaminant concentration in an effective absorption range. In the spray chamber the caustic solution is evenly distributed over the top of the packing bed by a single non-clogging spray nozzle.
Clean gas flows through a high efficiency mesh pad, which prevents mist carryover.
The caustic solution is collected in the recirculation sump, which has been sized large enough to provide a constant positive head for a recirculation pump.

Last Updated on Monday, 05 October 2009 21:45

Bay Products has a complete staff of field service technicians to provide installation assistance, start-up, traning, and performance testing.