English to Russian Science Chemistry; Chem Sci/Eng Карбамидная у

Руководство по установке для производства карбамида (мочевины)

1. GENERAL INFORMATION

The purpose of this document is to provide general hints concerning the typical main procedures for the start-up and shut-down of Urea Plant. Information herein contained shall in no way be intended as exhaustive operating guidelines/manual, but only as a qualitative and brief overlook of the major operational steps of the Urea Plant start-up/shut-down sequences. Detailed and exhaustive description of the above mentioned sequences for this project are part of the Urea Plant Operating Manual, which is outside the present Scope of Work.


2. UREA UNIT TYPICAL START-UP PHILOSOPHY

The typical normal start-up sequence is characterized by the following main phases:

 Heating up and hot bolting
The equipment shall be previously heated so as to bring them to the best conditions for a smooth start up. The plant heating is performed in order to avoid thermal stress to the material and possibility of crystallization of products in cold piping and walls. The high pressure synthesis section shall be heated up to the temperature of about 150-160°C before introducing the process fluids. Take into account that the heating speed shall never exceed the values recommended by the equipment manufacturers (about 30°C/h).

 Condensate draining before pressurization
Before feeding NH3 for H.P. loop pressurization all the condensate from process equipment of H.P. system has to be drained and than drain valves need to be closed.

 Ammoniation
This operation consists in the pressurization of H.P. loop with ammonia vapours up to achieve about 60÷80 kg/cm2 g and requires about 3 hours.

 CO2 compressor start-up (according to Manufacturer procedure)
 Feeding the reactor with CO2 and NH3

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