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7/18/2019 Process

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Process DescriptionIntroduction

The process described is for a Nickel Oxide Reduction Plant to be built for the client. The

plant will be located at Panki situated in Kanpur Nagar, Uttar Pradesh, India. ker

!olutions "#$ %td, !tockton on Tees, UK, has pro&ided a technolog' package which

has been used to carr' out a ("") b' ker !olutions, *u+bai, leading on to the

detailed design phase.

The +ain che+istr' of the process is the reduction of nickel oxide to nickel using

recirculating h'drogen gas through a reactor which contains the catal'st. In order to

ensure that the nickel catal'st is not oxidised back to nickel oxide once it is re+o&ed

fro+ the reactor, $O and air are also fed to the catal'st within the reactor in order to

for+ a coating around the catal'st. n' +oisture which is produced fro+ the reduction

step is re+o&ed in a knockout pot and sent to an effluent pond, which is outside the

scope of Pro-ect /. n' gases that re0uire to be &ented during the reduction, $O or

air stabilisation steps, or during the nitrogen purge steps will be &ented to a safe

location.

O&erall )escription

The process gas will be co+pressed up to the desired pressure b' the circulator. The

gas will be heated up due to this co+pression and therefore heat will be partiall'

re+o&ed fro+ the strea+ b' an after cooler and after chiller unit located downstrea+ of

the circulator during process steps when this is necessar'. Otherwise the after cooler and

after chiller will be b'passed so as to utilise the heat of co+pression in order to raise the

te+perature of the process gas. This will therefore reduce the a+ount of heating

re0uired b' the electric heater. Pressure letdown &al&e, located downstrea+ of the

$irculator, is ad-usted to kill the pressure of the gas strea+ being fed to the aftercooler

and afterchiller depending on the process step. The gas strea+ will then be fed to aseries of / heat exchangers 1collecti&el' called the interchanger2 where it will be heated

countercurrentl' b' the exit gas strea+ of the reactor. b'pass facilit' will be allowed for

the gas strea+ to partiall' b'pass the interchanger to allow te+perature control of the

cooled gas lea&ing the interchanger. The heated gas strea+ will then be further heated

up to the desired te+perature, as re0uired depending on the process step, b' an electric

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heater. The gas strea+ will then be fed to the reactor where it will react with the catal'st

and depending on the process step will either reduce the NiO to Ni 1section 2 or

stabilise the Ni b' for+ing a la'er on the catal'st so as to pre&ent the re3oxidation of Ni

1sections 4 # 52. The gas strea+ exiting the reactor will pass back through the

interchanger. The gas strea+ will then be filtered and fed to a second cooler and chiller

unit. Prior to feeding the cooler a &ent line will allow &enting of the +ain gas loop, if

re0uired, depending on the process step. The gas strea+ will be cooled in the cooler

and further in the chiller to cause the water 1produced in the reaction 6 see section 2 in

the strea+ to condense and be separated fro+ the gas strea+ in the downstrea+

knock3out pot. $ondensed water will be sent to the effluent pit. )uring other process

steps there will be no water being produced so the chiller can be b'passed to sa&e

energ'. $O, 7 and process air will all be supplied to the knock3out pot, depending on

the process step being carried out, where the gas will -oin the +ain process loop. The

additional gas is to replace losses fro+ the reaction or &ent. The gas strea+ lea&ing the

top of the knock3out pot will then feed into the suction side of the circulator where it will

be co+pressed and once again sent to the after cooler 8 after chiller unit. Nitrogen gas

used for the pressurisation 8 depressurisation stage and purging stage will be fed into

the +ain gas strea+, upstrea+ of the interchanger prior to heating and feeding the

reactor.

)etails of the process will be split into the following sections9

!ection

.: Reduction of NiO $atal'st

/.: 7ot N Purge

4.: $O !tabili;ation

5.: ir !tabili;ation

<.: !u++ar'

This docu+ent should be read in con-unction with the following docu+ents9

2 ker !olutions )ocu+ent =:=3:3=::=3::, Process )esign >asis.

2 ker !olutions Piping and Instru+entation )iagra+s 1P#I)s2, =:=3=::3:3%:: to%::=.

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2.0 Reduction of NiO catalyst

This plant is designed to reduce and stabilise a range of nickel catal'sts in a batch

process of between / to < da's duration, depending on the catal'st t'pe. Up to +/

of catal'st is charged into the reactor &essel and reduced in circulating h'drogen at a

+axi+u+ te+perature of =::?$. The actual te+perature &aries fro+ catal'st to

catal'st. The gas strea+ will be heated at a defined rate using an electric heater,

located upstrea+ of the reactor.

NiO 1s2 @ 7 1g2 3333A Ni 1s2 @ 7O 1g2

The reduction of nickel oxide to nickel is ther+all' neutral 3 it does not generate heat

or absorb it. Bater is produced in this reaction and is condensed b' cooling the gas

strea+ to approxi+atel' 4?$ b' using :C eth'lene gl'col. The condensate is

re+o&ed fro+ the s'ste+ using a knockout pot. The dried gas has a residual water

le&el of :.5 &olC and is recirculated o&er the catal'st.

3.0 Hot N2 Purge

fter reduction, the catal'st is purged with nitrogen at :?$ abo&e the reduction

te+perature 1=:?$ for the highest case2 for 4 hours to re+o&e an' absorbed

h'drogen. (ailure to do this will lead to a +ethanation reaction when $O is

introduced at the next step. The catal'st bed is then cooled down to D:E$ in

recirculating nitrogen.

4.0 CO2 Staili!ation

Nickel is +uch +ore stable as nickel oxide than it is as nickel, so it would therefore

rather undergo the oxidation back to nickel oxide.

Ni @ FO 3333A NiO

The catal'st has to be stabili;ed to allow it to be re+o&ed fro+ the reactor and packed

in dru+s for custo+ers.

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$O is bled into the s'ste+ to gi&e the appropriate $O8N at+osphere for a gi&en

period of ti+e to stabilise it, with the reactor bed +aintained at a +axi+u+ te+perature

of up to 55E$, dependent on the recipe.

".0 #ir Staili!ation

Once $O stabilisation is co+plete the bed is cooled. The +onola'er for+ed b' $O is

not co+plete and so+e unreacted sites re+ain exposed which react with O . In the

at+osphere of $O8N, process air is then slowl' bled into the catal'st to stabilise an'

re+aining reacti&e sites on the catal'st. This is highl' exother+ic process and if not

carefull' controlled will break up the $O +onola'er and lead to bulk oxidation and

associated te+perature runawa'.

)uring the air stabilisation the te+perature is +aintained around /:E$. The length of

ti+e the te+perature is held is around : +inutes but will be longer if there is a

te+perature rise.

fter the air stabili;ation process, O uptake tests are carried out for a nu+ber of ti+es

depending upon catal'st grade. (or this, the plant is kept in a boxed3up state and the

percentage decrease in ox'gen le&el o&er a period of half an hour is +easured. The

ox'gen concentration in the subse0uent steps is raised graduall' fro+ :. +ole C to a

+axi+u+ of 4 C depending on the catal'st grade. (inall' air is introduced to bring the

ox'gen le&el up to :C. fter acceptable le&els are achie&ed, the catal'st is unloaded

fro+ the reactor into dru+s.

$.0 Su%%ary

The following are the t'pical steps carried out for the reduction of Nickel based catal'st9

. $harge the catal'st into the reactor and box3up 1+anual operation2.

. Pressurise 8 depressurise the plant fro+ .5 bara to 5 bara at a+bientte+perature 4 ti+es with nitrogen to dri&e out air in the plant.

/. Repeat the pressurisation 8 depressurisation steps with h'drogen.

4. $irculate the h'drogen while heating the reactor at up to 5:E$8hr to a +axi+u+

te+perature specified b' the selected recipe 1ra+p rate T>$2.

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5. Pass h'drogen through the reactor at constant te+perature for <3Ghrs depending

on recipe.

<. Repeat the pressurisation 8 depressurisation with nitrogen to dri&e out h'drogen

fro+ the plant.

=. Pass the nitrogen through reactor for a 4 hour duration at a te+perature : to

:E$ higher than reduction te+perature. This N is &ented to at+osphere.

G. $irculate the N to cool the reactor to +axi+u+ te+perature of D:E$.

D. Pass the $O into the reactor until a 5:85: +ixture with N is reached. $irculate

and reheat the reactor to 55E$ and hold at this te+perature for a specified

nu+ber of hours.

:. $ool the reactor b' circulating the gas.

. Pass air into the s'ste+ +aintaining :.C O in the reactor inlet gas. $ontinue

this air stabili;ation until the reaction front passes down the reactor, then cool the

reactor to /:E$.

. $arr' out the O uptakes according to the recipe.

/. $arr' out an air purge to increase the O le&el up to the air purge &alue

1approxi+atel' :C2.

4. )ischarge the catal'st fro+ the reactor 1+anual operation2.

process

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