Frick Rotary Screws Escape Industrial Refrigeration Niche
Uses expanded to natural gas, other applications
In the mid-1990’s, faced with a static business climate after more than a century in the industrial refrigeration compressor business, Frick began looking for other applications for screw compressors.
“While product cooling and ice making industries remained a key business, we found opportunity in natural gas,” explained John Ferguson, director of Frick sales. Now as a unit of Johnson Controls Inc. (JCI), a Fortune 100 company that includes York Process Systems, Frick screw compressors serve a broad range of niche markets.
“We serve many applications in refrigeration, natural gas, specialty gases, as well as custom compressors for the U.S. and other navies,” said David Seiler, Frick OEM sales manager.
Through York Process Systems, Frick’s packaged refrigeration compressor systems are used in chemical and petrochemical, oil and gas processing, industrial gas production, oil and gas transportation and storage, and other applications. Outside of the refrigeration market, which still makes up 60% of the business, Frick compressors are applied in gas gathering, gas processing, fuel gas boosting and vapor recovery applications.
“Rotary screw compressors are our core competency,” explained Seiler. “In the 1990s we started a program of OEMs to package screws, being very selective with the product, to ensure success and giving the packagers a franchise.” Today, Frick OEMs include Compass Compression, Compressor Systems Inc., Enerflex, Exterran, Natural Gas Systems Group, Sage Energy Corp. and UE Compression.
The “workhorse” of the Frick product line is the TDSH/PDSH series, designed to compress a variety of gases in many different applications. The series has 21 different models with five rotor diameters ranging from 6.417 in. to 16.062 in. (163 to 408 mm) and length to diameter (L/D) ratios up to 2.4.
The TDSH series, with cast iron pressure retaining housings, is used in typical refrigeration and natural gas applications up to 400 psig (27.6 bar). It is also offered with optional nodular iron pressure retaining housings up to 600 psig (41.4 bar). The PDSH series, with cast steel housings, is used in gas processing or industrial refrigeration in chemical and petrochemical applications up to 600 psig (41.4 bar). The compressors are direct drive at speeds from 600 to 4500 rpm for rotor sizes up to 9.173 in. (233 mm) or 600 to 3600 rpm for larger sizes. Power ratings of the series range from 250 to 6000 hp (186 to 4474 kW).
Frick compressors utilize 100% anti-friction bearings. Cylindrical roller bearings handle radial loads, and angular contact bearings, aided by a balance piston, absorb thrust loads. Roller bearings maintain accurate rotor positioning to minimize internal leakage and inefficiency. The antifriction bearings minimize frictional power losses.
Injected oil serves to lubricate the bearings, balance piston and seal and fill any leakage paths between and around the rotors to prevent internal gas recirculation losses. Oil injection also minimizes noise and vibration, keeping the compressor cool by absorbing much of the heat from compression. System differential pressure is normally sufficient for supplying oil to the bearings. Compressor housings are machined to provide static oil reservoirs for the bearings. Therefore, Frick compressors can run in most applications without an oil pump.
A stepless hydraulic or manually actuated slide valve moves axially along the rotor mesh line to provide unloading. Unloaded gas is internally bypassed back to suction before compression has begun, allowing the compressor to efficiently accommodate system requirements. A hydraulically actuated slide stop adjusts slide valve length to optimize internal discharge pressure. This matches compressor volume ratio (Vi) to system pressure ratio and eliminates the power penalties associated with typical screw compressor under- or over-compression. Vi is infinitely variable from 5.0 to 2.2 and also 3.0 to 1.7 on some models.
The SGC series, referred to by Frick as the “thoroughbred” of its line, is a newer version of the TDSH that is modified to simplify packaging. It is equipped with a horizontal gas inlet accessible from either side, an integral suction strainer to protect the compressor from ingestion damage, and control valves mounted on the compressor. The series has 17 direct drive models with rotor diameters ranging from 7.598 to 13.976 in. (193 to 355 mm).
The SGC has internally machined oil passages that reduce the risk of leaks associated with external piping. It has an optional adapter for direct mounting to flanged drivers, which improves alignment, seal life and noise. Power ratings of the series range from 450 to 3500 hp (336 to 2610 kW).
The XJF/XJS series has 16 models, with rotors ranging from 3.741 to 5.945 in. (95 to 151 mm). It has a horizontal inlet with strainer and is configured in a small footprint with an internal gear drive. A stepless hydraulically or manually actuated slide valve provides unloading down to 25% of full load capacity. Vi is adjustable in three steps: 2.2, 3.5 or 5.0. XJF 95 and 120 models are supplied with a C-flange close-coupled motor adapter. The XJF 151 has an optional C- or D-flange or SAE 2 motor adapter. Power ratings of the series range from 100 to 436 hp (75 to 325 kW). A range of standard gear sets can accommodate a range of driver speeds.
The NGC series, which Seiler described as the “gas masher,” is a version of the SGC series with an integral internal gear drive designed to match gas engine speeds for field gas applications. He said it is the only bare shaft screw compressor in the industry that was developed specifically for natural gas applications.
First introduced in 2001, the NGC series now has 32 models with rotor diameters ranging from 7.598 to 13.976 in. (193 to 355 mm). All models have an assortment of internal gear combinations to allow optimal matching with power and capacity requirements.
The compressors are designed to allow gear sets to be changed in the field, without requiring the compressor to be removed from the package. This allows the compressor to be run faster to maintain capacity and load the driver as field pressure declines. Available models cover the range of 50 to 2550 hp (37 to 1901 kW).
The NGC compressors are designed to be foot-mounted and direct coupled to either a natural gas engine, diesel engine or electric motor driver. Models 100 through 300 have an integrated suction strainer with horizontal inlet on the left or right sides. The larger models 400 and 450 do not have the integrated strainer and are arranged for vertical inlet. Pressure ratings are available to 600 psig (41.4 bar). A stepless hydraulically actuated slide valve provides unloading down to about 10% of full load capacity for most models. VI is infinitely variable from 5.0 to 2.2 and also 3.0 to 1.7.
The Frick RWF-II and RXF series are offered as standard packaged units for the industrial refrigeration market. Standard and custom engineered packages are designed for use as boosters or high-stage machines on ammonia, halocarbon or hydrocarbon refrigerants and are shipped completely assembled. Variable speed drives and/or slide valves are incorporated on the RWF-II for capacity control from 100 to 20%. Each package includes the electric motor driver, oil separator/reservoir, valves, controls, and any other accessories needed to operate and control the compressor.
Frick produces its own Quantum control panel, which it describes as the most technologically advanced screw compressor control in the world. The high-speed PC-based processor is faster and more powerful than microprocessor-based systems. The configurable system provides control, real time display and historical trending capabilities and includes a 10.4 in. (264 mm) color graphics display. Set-points are stored in flash memory, which requires no battery back-up.
“The Quantum HD panels are key to our success. They are built by engineers who understand screw compressors,” Seiler said.
Frick also offers its own proprietary Vyper variable speed drives with 60 Hz ratings ranging from 305 to 913 hp (227 to 681 kW). Intended primarily for the industrial refrigeration market, the drives offer enhanced energy savings and reduced maintenance costs by providing fast, precise and wide-ranging response to rapidly changing loads.
Johnson Controls designs and manufactures all Frick screw compressors and control systems in Waynesboro, Pennsylvania, where Frick Co. began in 1853. The Waynesboro plant occupies 465,000 ft2 (43,201 m2) on a 50 acre (20 ha) site.
Frick screw compressors continue to evolve with time and now encompass 86 models with broad parts commonality.
“Frick entered the screw compressor business with some radical ideas back in 1982,” explained Joseph W. Pillis, director of global engineering, industrial refrigeration. “We were the first to develop two slides to adjust and control Vi and capacity automatically. Managing Vi greatly increases operating efficiency. This is an advantage in the gas patch for declining well pressure as it can chase the well pressure down and keep the unit loaded.”
Frick developed its own electronic control system to control the slide valves and take full advantage of its capability.
Pillis said that Frick compressors were the first to use 100% anti-friction bearings, which improve reliability and enables 70 to 80% of Frick machines to be applied without oil pumps. He indicated that there are Frick machines in the gas patch with 50,000 to 60,000 hours of operation and units in clean, dry gas service with over 140,000 hours without servicing.
The anti-friction bearings can run hotter (up to 300°F discharge and 280°F suction) than fluid film bearings, which helps operators keep the process gas above the dew point temperature. He said this capability, along with the Frick control system and appropriate package design, keep water in gaseous form and enables standard Frick machines to compress wet CO2 and wet H2S gases.
Over time, Frick has developed its own rotor profiles, tailored to gas type, which limit pulsations and noise, while optimizing performance. “We have pushed our pressure ratings to 600 to 700 psig (41.4 to 48.3 bar) and now special models to are rated at 900 to 1200 psig (62.1 to 82.7 bar), which allows Frick compressors to fit new applications,” said Pillis.
The 5.94 in. (151 mm), 900 psig (62.1 bar) HPSH model was released for production in 2010, and the company reported that 30 units have been applied in CO2 cascade systems, ammonia heat pumps, and natural gas boosters to 725 psig (50.0 bar). A 10.63 in. (270 mm) model is currently under development.
First developed in 1991, more than 6000 of Frick’s large 13.98 in. (355 mm) models have been produced. Seeing a need for an even larger unit, Frick introduced a 15.75 in. (408 mm) model in 2008-9, with more than 24 units now in service in process gas and natural gas applications. It can run up to 3500 rpm, with L/D ratios to 2.1, producing more capacity than any other standard screw compressor. Frick product development is supported by a 25,000 ft2 (2323 m2) research and development lab with R134A, ammonia, CO2, N2 and N507 closed loop test capabilities.
CoolWare, Frick’s quoting program, which was developed in-house and is validated by lab testing and field experience, looks at the results of rigorous calculations on each unit quote. It sets max permissible operating conditions and provides predicted performance for the application conditions.
“We package lots of screws for industrial refrigeration and other applications, so we know what it takes to produce a good system. We have shared that knowledge with our select group of OEM packagers to develop reliable and cost efficient natural gas packages,” Seiler said. “Frick is a true process compressor, available in a large number of models and with operating experience with about 100 different types of gases,” he added.
Company officials said that they have built 130,000 screw compressors since introducing the line in 1982, with 12,000 in natural gas applications. Currently 300 to 700 bare shaft screw compressors per year are produced for the gas market.
“Frick has been a dynamic manufacturing company, constantly trying to do something different and better to improve and increase our products,” Seiler said. “JCI has been a positive influence on our manufacturing processes and process control. We were good as Frick, but we’re now even better under JCI.”