Disclosed herein is an air shower for dust collectors and, more particularly, in-line “air blade” showers for mobile dust collectors.
Inhalable and/or respirable silica dioxide (SiO2) is a major problem facing the oil and gas (O&G) industry. Silica dioxide is a commonly occurring element found in two forms—crystalline and amorphous. Quartz and sand are common examples of crystalline silica. Silica dioxide is particularly hazardous when it is broken down, creating inhalable or respirable silica dust (very small crystalline particles and/or amorphous particles). The Center for Construction Research and Training (CPWR) has stated that “inhaling crystalline silica dust can lead to silicosis, bronchitis, or cancer as the silica dust becomes lodged in the lungs and continuously irritates them.” According to the World Health Organization (WHO), whenever people inhale airborne silica dust at work, they are at risk of occupational disease. Year after year, both in developed and in developing countries, overexposure to silica dust causes disease, temporary and permanent disabilities and deaths. Silica dust in the workplace may also contaminate or reduce the quality of products, be the cause of fire and explosion, and damage the environment.
Field workers in the O&G industry are exposed to silica dust which can cause silicosis through over exposure. While personal protective equipment (PPE) is generally employed to prevent exposure, secondary exposure (for example, from residual silica dust on clothing) is sometimes forgotten.
Generally, air shower systems are used to remove contaminants from a person before or after they enter or leave a clean room. Clean rooms are used so that the person will be as free from contaminants as possible before they enter “sterile” facilities such as hospital operating rooms, research laboratories, semiconductor fabrication facilities, and pharmaceutical fabrication facilities. It is imperative that these facilities be free from contaminants such as dirt, dust, skin cells, bacteria, and mold.
In use, a person enters the air shower through a door that then closes behind him. Known air showers use a large air pumping system to power air flow. The air pumping system may include a fan and/or compressed air. (The use of compressed air necessitates an additional, substantially larger, air tank to supply the demands of the air shower. Compressed air also presents a health risk to people as the high pressure can cause injuries, such as a failure in the regulating system that could cause tissue damage.) Once inside the air shower, air nozzles (installed on the vertical walls and/or the ceiling of the air shower) blow air onto a person's surfaces to remove contaminants. Exhausted air and contaminants are removed from the air shower via air discharge holes. The contaminants may be filtered from the air, and may be stored if required by laws relating to the collection and disposal of contaminants. The filtered air is either recirculated through the air shower or is exhausted out into the environment. These known air showers are generally large and expensive. Known air showers require their own transport and possibly even a crane to move them. The expense and difficulties associated with known air showers limits their utility.
Patents describing known air shower systems include U.S. Pat. No. 4,267,769 to Davis et al. (the “Davis reference”), U.S. Pat. No. 4,624,690 to Byrnes (the “Byrnes reference), U.S. Pat. No. 4,765,352 to Strieter (the “'352 Strieter reference”), U.S. Pat. No. 4,967,645 to Mattson (the “Mattson reference”), U.S. Pat. No. 5,558,112 to Strieter (the “'112 Strieter reference”), U.S. Pat. No. 5,692,954 to Lee et al. (the “'954 Lee reference”), U.S. Pat. No. 5,746,652 to Lee et al. (the “'652 Lee reference”), U.S. Pat. No. 5,816,908 to Tsou (the “Tsou reference”), U.S. Pat. No. 7,465,225 to Ohmura et al. (the “Ohmura reference”), U.S. Pat. No. 7,887,614 to Yamazaki et al. (the “Yamazaki reference”), Patent Cooperation Treaty (PCT) Application No. PCT/CN2012/082839 to Tianjin Tianxing Electronics Co., Ltd. et al. (the “Tianjin reference”), Chinese Patent No. 103464420 to Weiping et al. (the “Weiping reference”), and Korean Patent No. 10-1449938 to Cho (the “Cho reference”).
What is relatively common in the O&G field are mobile vacuum systems (also referred to as “dust collectors”) designed to capture and remove silica dust during on-site O&G operations. Fracking, specifically, requires large volumes of sand (hundreds or even thousands of tons) to be pumped downhole. This sand is generally silica sand, and, therefore, any movement of the sand generates silica dust. The use of coated sand can lower the generation of silica dust, but it is not cost effective. Washing the sand is similarly costly and any further movement of the sand will simply create new silica dust particles through impaction. PPE can be worn to protect workers, but this is considered a last resort and does not help when site operations are near residential areas.
Known mobile dust collectors are large trailer mounted units capable of moving very large volumes of air at low pressure. Exemplary dust collectors include, but are not limited to, the mobile vacuum machine described in U.S. Pat. No. 4,578,840 to Pausch (the “Pausch reference”), the portable vacuum cleaning system described in U.S. Pat. No. 5,030,259 to Bryant et al. (the “Bryant reference”), the mobile pneumatic material transfer machine described in U.S. Pat. No. 5,840,102 to McCracken (the “McCracken reference”), the vacuum-cleaning apparatus for a stable described in U.S. Pat. No. 7,430,784 to Cowan (the “Cowan reference”), and the mobile work trailer described in U.S. Pat. No. 9,073,473 to Cramer (the “Cramer reference”). In addition, dust collectors may include Industrial Vacuum Equipment Corporation's Cyclone 20DC Portable Diesel Powered Dust Collector 20000CFM, ARS Recycling Systems, LLC's DC45 45000CFM, Robovent's BNM6818CT200 20000CFM, Entech Industries Ltd's Cyclone 45DC Mobile Dust Collector 45000CFM, and Entech Industries Ltd's Cyclone 20DC Mobile Dust Collector 20000CFM.