Features Of Rix CNG Equipment

All Rix Air & Gas equipment is purpose-designed for natural gas - the compressors are NOT modified air or other process compressors - every component has been designed and produced specifically for use with natural gas. In particular, Rix compressor technology has favoured water-cooled reciprocating compressors as being the most economic and reliable for CNG use. Earlier experience with both air-cooled and hydraulic compressors has revealed inherent design drawbacks with the type of equipment. The most popular range of compressor is 250 to 400 cubic metres per hour, using electric motors of 42 to 75 kilowatts (60 to 100 HP) depending on the inlet pressure available. Rix Services' compressors can be engineered to take advantage of the energy saving available by utilising high inlet pressures, unlike some other manufacturers where the line pressure must be regulated down to 2 or 3 bar to suit the inlet capability of the compressor. Rix compressor design is based on API-618 standards, the most important internationally recognised standard for gas compressors. Heat exchangers are built to ASME VIII design standards and are of multipass gas path, shell and tube type.

Other salient design points are:
Low operating speeds, typically 400-700, giving higher efficiency, low piston speed and longer valve life; A heavy duty crankcase. The crankcase sub-assemblies are fully pressure lubricated and rated for continuous duty also of Rix manufacture. The crankcases are rated to 500HP & 500 degrees F, well above maximum installed horsepower. Connecting rods are rated to 10,000 pounds, again well in excess of the loads experienced in service, which are generally in the 6,000 to 8,000 psi range. In the Rix lubricated machines, oil is removed from the gas stream by a series of high pressure in-line filters; Low rotational speeds are enforced by very high inertia flywheels, resulting in very smooth running compressors with high drive belt life; Water cooling results in higher piston ring life, quieter running and in the case of compressors used in daughter station applications, waste heat from the cooling water can be used to heat the regulated gas, thus avoiding the use of a separate energy-wasting electric or thermal heating unit; Proprietary parts are used as far as possible. This is to ensure continuity of supply, and economic part prices, components being obtained from substantial international companies who specialise in the supply of parts for high pressure compressors. For example Rix use "Hoerbiger " valves, " Wika " switch gauges and " Mega " lubrication equipment; Piston rings are cast iron and PTFE type for long ring life and minimal bore wear, and can be run non-lubricated if necessary. However, Rix believe in direct lubrication of the cylinder bores to increase both piston ring and valve life. Non-lubricated compressors are at risk where dry gas is involved, leading to high maintenance costs. Electronic reduced voltage motor starters offer smooth starting without electrical interference to other equipment, and low cabling costs. Other forms of starter may be fitted on request; liquid resistance or star delta being available as stock production.

REFUELLING CAPABILITY OF EQUIPMENT

RIX 2JJS3G-178 PACKAGE

· Compressor output: 425 m3 /hr @ 15psi inlet

· Storage capacity: 480 m3 at 250 Bar

· Storage utilisation for 3 line system: 66.6%

· Average time to fill vehicle: 3 minutes

· Capacity of average fill: 10 m3

· Based on four refuelling and four minutes being average fill time per outlet. Maximum fill per hour 4 x 60 = 60 Fills from refuelling outlets 4

· Refueling capability in first hour Available Gas = Compressor output + available from station storage = 425 + (480 x 66. 6% utilisation ) = 425 + 320 = 745m3 Number of fills = available gas average fill = 745/10 = 74 fills

· Refueling capability in second hour Storage is 33.3% of full capacity therefore only minimum amount of this will be available to refuel vehicles, e.g. around 25% (due to slowness of pressure transfer ) Available gas = compressor output + available gas from station storage = 425 + (25% x 160 ) = 425 + 40 = 465 m3 Number of fills = available gas average fill = 465/10 = 46 fills

· In proceeding hours thereafter only compressor output is available for refuelling. Available gas = 425 m3 Number of fills = available gas average fills = 425/10 = 42 fills

Total Refueling Capability First and second hour and proceeding 14 hours: = 74 + 46 + (42 x 14) = 708 fills of 10 m3 at 200 Bar.

Rix Air & Gas Ltd

31 Hillside Road

Glenfield

Auckland

New Zealand

To contact us:

Phone: +64 9 273 3480

Fax: +64 9 273 3485

E-mail: rix@ashair.co.nz

An Ash Air (NZ) Ltd Group Company