Sulfur Recovery Tail Gas Analyzer, The Ametek Model 888

Sulfur Recovery Tail Gas Analyzer, The Ametek Model 888 photo

The Ametek Model 888 Sulfur Recovery Tail Gas Analyzer, the successor of the 880 NSL uses field-proven and highly reliable UV technology to accurately monitor the H2S and SO2 concentrations in sulfur recovery tail gas. This compact, rugged analyzer mounts directly on the process pipe, eliminating the complexity and safety issues of fiber optic coupled photometers.

Ametek Process Instruments has been the leader in tail gas
analysis for over 40 years, with more than 1,100 installed 880
NSL analyzers and more than 100 million hours of run time.
The 888, the successor of the 880 NSL, uses field-proven
and highly reliable UV technology to accurately monitor the
H2S and SO2 concentrations in sulfur recovery tail gas. This
compact, rugged analyzer mounts directly on the process
pipe, eliminating the complexity and safety issues of fiber optic
coupled photometers. The 888 is the evolution of a well-proven
formula. All the best elements of the iconic 880 NSL are still
there: lamp life between 3-5 years, no shelter required, and
steam blow back for ammonia salts.


How does the Sulfur Recovery Tail Gas Analyzer work?

1. Demister

The heart of the sample handling is an improved sulfur demister. The 888 uses the proven sample handling technique of a “reflux” demister with double demister pads (316SS top and PTFE bottom). The demister pads are held in place on a shaft with retention rings to withstand the optional hot condensate “steam blowback” for ammonia salts. The demister is connected with vacuum compression O-ring fittings, easily accessed, requiring only minutes to disassemble and service.

2. Xenon flash lamp for Sulfur Recovery Tail Gas analyzer

The 888 uses a pulsed xenon flash lamp as the broad band UV source. This lamp is an improved version of the field proven design used in the 880 Tail Gas Analyzer. The lamp is operated in a pulsed mode to extend the lamp life time. Automated validation zero gas measurements are used to compensate for the long-terms effects of decreasing lamp output and the accumulation of process residue on gas cell windows.

3. AMEVision/digital communications

AMEVision is an icon-driven graphical interface with a color display for local communication with the analyzer. It provides screens showing trending functions, predictive maintenance indicators, analog output verification, time-stamped alarm/event log and more. In addition, the 888 has a remote PC web browser-enabled interface (no software required) over TCP/IP Ethernet.

Sulfur Recovery Tail Gas Analyzer, The Ametek Model 888 AMEVision HMI

4. Thermal management

A highly effective thermal insulating barrier, extruded aluminum convection heater and advanced thermal management algorithms reduce the internal temperature of the electronics enclosure by 15°C (27°F) without the need for external cooling. The result is an industry-first 60°C (140oF) specification for ambient temperature and a 75% improvement in electronics life. The 888 is suitable for installation in hot climates, requiring only a simple sunshade.

5. Flange temperature RTD and alarm

An embedded RTD in the process connection flange provides an alarm for poor quality steam. This advanced warning eliminates unexpected plugging.

6. Photometer of the Sulfur Recovery Tail Gas Analyzer

The Ametek Model 888 Sulfur Recovery Tail Gas Analyzer UV photometer uses four separate detectors each measuring a different narrow range of UV wavelengths. The light from the sample cell is divided into four separate channels using a combination of beam splitters and mirrors. The intensity information from each of the four detectors is used to calculate the H2S and SO2 concentrations using a factory-established calibration. The temperature of the photometer is carefully controlled to optimize the accuracy and precision of the reported concentrations. During the zero and span cycle an automated multi-point photometric span calibration is performed on each of the four channels. The source pulse sequencing is automatically varied to create an intensity calibration for each detector channel. The 888 is uniquely capable of automatic intensity calibration, but the optical system can also be diagnosed with a removable filter.

The Ametek Model 888 analyzer Filter Photometer

7. Auto flow control

The 888 monitors the pressure differential between the process and the sample aspiration and automatically adjusts the flow rate relative to the process pressure. During startup, shutdown, turn down, plugged rundowns and any time there
is entrained sulfur leaving the final condenser, the flow rate
can be minimized which reduces sulfur mist take-up.

8. Steam jacketed process connection valve

The 888 has the same footprint and steam jacketed ball valve that was used for the 880 analyzer. The steam jacket is a monocoque design and is rated for a cantilever force up to a force 5 hurricane wind. An 888 analyzer can be swapped over from an 880 installation while the process is on line, with zero egress of process gas in less than eight hours.

Hot air and condensate steam blowback

Sulfur Recovery Tail Gas Analyzer, The Ametek Model 888 illustration steam blowback flow

The 888 does not wait for the plug, it reacts to the root cause. Incomplete combustion of ammonia in the SRU process reacts with the sulfur compounds to form ammonia salts, which can plug the demister. These salts are not removed by air blowback, but they are water soluble. Hot condensate steam blowback provides a steam propelled blast of hot water to dissolve any salts that have accumulated within the demister. The 888 is also equipped with anti-clogging hot air
blowback features that are automatically initiated if plugging is detected by the smart diagnostics.

The Ametek Model 888 Sulfur Recovery Tail Gas Analyzer is the evolution of a well proven formula. All the best elements of the iconic 880 NSL are still there; Four year lamp life, no shelter required and steam blow back for ammonia salts. Building on this success the 888 offers improvements in a number of key areas.


Features of the Ametek Model 888 Sulfur Recovery Tail Gas Analyzer

Reliability

Ametek’s third generation Sulfur Recovery Tail Gas Analyzer, the 888 takes reliability to the next level by providing solutions to the three most common external failure modes:

  • Automatic flow control for proactive response to adverse process conditions
  • Flange temperature alarm for early warning of poor quality steam
  • Extended ambient temperature range to 60°C

Ametek listened to customer feedback from

Maintenance

We listened to customer feedback from operations, analyzer technicians and process engineers:

  • Smart diagnostic models identify, communicate, and react to potential problems
  • 2X over range measurement allows an informed response to process upsets
  • Worldwide factory support in over 50 countries

Safety

Hazardous operation improvements, with the analyzer technician in mind:

  • Close coupled, easily accessible but process isolated demister
  • Complete isolation from the process with double block valves
  • Remote PC Web enabled interface

Specifications of the Model 888 Sulfur Recovery Tail Gas Analyzer

Methodology Non-dispersive UV
Measurement range SO2: 0-1%; H2S: 0-2% (standard output range) air demand, excess H2S or excess SO2 (as control outputs)
Accuracy H2S and SO2: ±1% of full scale
Reproducibility ±1% of full scale
Speed of response 90% in less than 15 seconds, typical
Calibration Automatic multi-point photo span validation
Sample flow 2 L/min typical
Outputs (analog and digital) Four 4-20 mA, self-powered (24 VDC), linear, 1000 ohms load proportional to H2S, SO2, and either excess H2S or ratio
Four programmable relay contacts (30 VAC, 60 VDC, 10 VA, resistive load)Four programmable relay contacts (30 VAC, 60 VDC, 10 VA, resistive load)
RS485 Serial Communication Port, two-wireRS485 Serial Communication Port, two-wire
Inputs One isolated digital input, contact closure; 5 VDC @ 2.5 mA
Communication RS485 serial port, Ethernet, Modbus. Remote dial-in capabilities available with AMETEK web-enabled software
Ambient shaded temperature -20 to 60°C (-5 to 140°F)
Customer-supplied items 2″ 150# or DIN equivalent RF stainless steel flange connection
Ingress protection IP65 (NEMA 4X)
Enclosure material 316 stainless steel
Physical dimensions (W x H x D) Zone 1: 113.8 x 99.3 x 32.1 cm (44.8 x 39.1 x 12.6 in.)
Class I Division 2: 91.4 x 99.3 x 32.1 cm (36 x 39.1 x 12.6 in.)
Approximate weight Zone 1: 110 kg (242.5 lbs.)
Class I Division 2: 99 kg (218 lbs.)
Electrical 120 or 240 VAC 50/60 Hz 500W, single phase
Instrument air/nitrogen 380 to 520 kPa (55-75psig)
Steam pressure 620 to 792 kPa (90-115 psig) for optional jacketed ball valve and 210 to 345 kPa (30-50 psig) for optional blow back
Approvals and certifications UL/CSA: Class I, Division 2, Groups A, B, C, D
ATEX: II 2G Ex d pxb IIC T3 Gb
IECEx: Ex d pxb IIC T3 Gb
Russia (CU 1Ex db pxb IIC T3 Gb X)
Complies with all relevant European directives



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Sulfur Recovery Tail Gas Analyzer, The Ametek Model 888
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