IPE-TM-900-02 — Ejectors | Engineering Library

1. Purpose

This procedure provides a guideline for completing Project Specification 809 - Ejectors.

2. General

Ejectors are required to:

hydrocarbon-free equipment and process loops, such as reactor circuits, prior to personnel entry.

air-free reactor circuits prior to start-up.

Information Required

Process Unit Name	The process unit name shall be reported consistent with the official process names recorded in Inflection Point Engineering General Reference .
Item Number:	The item number format and ejector designation shall be consistent with the F-EDI-02, “BEDQ. The letter J is typically used to designate an ejector service.
Process Volume: (Reactor Circuit Volume)	The reactor circuit volume is calculated per Procedure
Suction Pressure:	The default suction pressure level is 5 inches Hg (130 mm Hg). This pressure level has been selected for two reasons: It approaches the minimum vacuum level for a single stage ejector. It maximizes water removal for initial plant dryout / start-up.
Time:	The minimum evacuation time is designed to be consistent with the general availability of off-the-shelf single stage ejectors. Typically, ejectors are available which can evacuate at a maximum rate of 800 ft3/min.
	Round the evacuation time up to the nearest 15 minutes and report. If the evacuation time exceeds 60 minutes, consult a specialist. For example, a recent 53000 BPD CCR Platforming Process Unit with 60,000 ft3 evacuation volume required a custom engineered ejector ($6000+$5000 for silencer, 3000#/hr motive steam) to meet Inflection Point Engineering’s traditional 1 hr. evacuation time criteria. Any extension of the evacuation time should be discussed and approved with the appropriate process technology specialist and OTS representative. The capital investment for the hogging ejector and silencer is most often justified when compared to the N2 required to perform a sufficient number of purge cycles to get the reactor circuit oxygen content reduced to required levels.
Suction Temperature: Maximum	Report the maximum site ambient temperature from the Inflection Point Engineering BEDQ for the normal temperature. The default maximum operating temperature is reported as 300F (150C). This is based on the normal system operating temperature, cool down time, and cooling effect from purge cycle(s).
Steam Level:	Use medium pressure (MP) steam for ejector service whenever it is available. When MP steam is not available, either HP or LP steam may be considered. However, the engineer should recognize the use of LP steam will incrementally increase the size and cost of the hogging ejectors. When the refiner has indicated usage of MP steam shall be minimized to integrate with overall steam balance, it is recommended that MP still be considered since the ejector is an intermittent, short-term user.
Steam Conditions:	Obtain steam conditions from the BEDQ.

4. Project Specification

Complete the standard template Project Specification 809E, “Ejectors” (English) or Project Specification 809M, “Ejectors” (Metric) by inserting the Process Unit Name, Item No., reactor circuit volume, time, suction temperature, and steam conditions. See Attachment 1 for a Legend Example. In the event the design steam pressure and temperature have not been provided in the BEDQ, the note "By Contractor" with an asterisk (*) may be used.

Enter Process Unit Name Here

Steam Jet Ejector, Item No

Application

Furnish one steam jet ejector suitable for the following service:

Evacuate equipment with a volume of XXX cubic feet, from atmospheric pressure to 5 inches Hg

absolute in XXX minutes or less. The normal suction temperature will be XXXF.

Fluid pumped: Air

The ejector shall also be expected to handle nitrogen with trace hydrocarbon gases at suction temperatures up to 300F. The vendor shall define the ejector performance, i.e. evacuation time, and suction pressure achievable, under these alternate conditions.

The contractor shall provide accessories such as a motive inlet assembly consisting of: steam strainer, steam inlet gate valve, interconnecting piping. The ejector nozzle shall be stainless steel, the steam chest shall be steel and the suction chamber and diffuser shall be cast iron or fabricated steel.

All gaskets shall be manufactured from non-asbestos materials. Gaskets for flange connections shall be spiral wound.

All flanges intended for use with spiral wound gaskets shall have a flange surface finish of 125 Ra minimum to 250 Ra maximum. Finishes shall be judged by visual comparison with surface finish roughness standards conforming to ASME B46.1.

This service will be required only on start-up or shutdown. The vendor shall specify steam consumption.

Steam Conditions:

Process Area Header: Minimum: XXX psig at XX F

: XXX psig at XX F

Maximum: XXX psig at XX F

Design: XXX psig at XX F

Contractor to advise steam conditions (pressure/temperature) at ejector inlet based on final piping layout.