Recuperação de Soda Cáustica

Instalação de Recuperação de Soda Cáustica

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Todos sabemos que o mercado mundial passa por um período difícil e todas as indústrias são afetadas.   A concorrência é grande e já atingiu as margens de preços e rentabilidade.  Nesta realidade desagradável deve-se realmente começar a pensar novamente sobre o lucro, analisando os vários caminhos que estavam sendo ignorados em tempos melhores.A maneira ideal é analisar as alternativas, buscando pontos para poupar desgastes dos diversos recursos e recuperá-lo rentavelmente, sempre que possível.  

A  UNITOP é a empresa precursora na recuperação de resíduos nos últimos 35 anos, oferecendo vários projetos, tais como sistemas de recuperação de calor, a recuperação de sal e sistema de recuperação de soda cáustica.

 

INTRODUÇÃO  

A mercerização na Indústria Têxtil gera um líquido cáustico diluído, que é drenado para tratamento de efluentes e cria graves problemas no cumprimento das normas ambientais.  O sistema de recuperação de soda cáustica, concentrando água de lavagem e usando o mesmo de volta na Mercerizadeira, é a única solução viável.

O PRINCÍPIO

Sob o sistema de recuperação de soda cáustica, a soda cáustica em baixa concentração é aquecida até seu ponto de ebulição com a ajuda de uma fonte de calor e os vapores gerados, devido à ebulição, são usados para aquecer o líquido fraco.  Este líquido quente é então “esguichado” em baixa pressão e os vapores gerados são usados novamente. O líquido fraco é concentrado para 250-300 gpl como no caso da mercerização seca ou a 450-500 gpl em caso de mercerisação úmida que pode ser reutilizado com um menor complemento de soda cáustica.

OPERAÇÃO

A lixívia cáustica fraca, aprox. 5-6 Be ( 40 – 50 gpl ), é coletada da caixa de impregnação e lavagem  e armazenada em tanque de armazenagem.  Então é conduzida a uma unidade de filtragem para suspensão dos sólidos, penugens, etc

A alimentação no Sistema de Recuperação – CRP – passa, então, através de uma séria de pré-aquecedores que pré-aquecem o efluente da lavadeira com o with the help of flash vapors from the condensate flashes ensuring minimum steam loss in heating the Wash liquor to its boiling point. The liquor in the tubes comes in contact with the steam in the shell side of heater 1 and the liquor starts boiling. The vapor liquor mixture enters the flash vessel through a tangential entry and the vapors get separated and enter the shell of the 2nd stage. The boiling in the successive effect takes place due to lower pressure created with help of a water ring vacuum pump. Due to lower pressure the boiling point of the liquor is reduced and it starts boiling. The concentrated liquor enters the 2nd heater due to the pressure difference and comes in indirect contact with the generated vapors and the same procedure is repeated. The concentrated product is removed from the last stage by a product pump. This later is taken either to a storage tank or to a Concentrated Lye purification system .
Under caustic recovery system / caustic soda recovery plant vapors generated at the last stage need to be condensed. This is done by either HOT WATER or an ADIABATIC EVAPORATOR system. In case of a hot water system, water at room temperature is passed through tubes of an exchanger and it gets hot due to the vapors. This hot water is uncontaminated and hence can safely be used in the process or the boiler as per the requirement.
In some cases where the hot water generated cannot be effectively consumed the effluent is passed through the exchanger and sprayed in an Adiabatic Evaporator Here the waste heat is lost in form of vapors and hence effective steam consumption of steam is reduced. Also nuisance of excess hot water is eliminated.

APPLICATION

Under caustic recovery system / caustic soda recovery plant , Caustic concentration has applications in every industry where dilute caustic is produced due to washing and the concentrated liquor can be reused Various applications where caustic is reused are :

Knit mercerising
Knit mercerising usually has very few impurities such as size, starch and hence the recycled caustic is also pure. The recycled caustic can be reused for a longer period of time before the cumulative impurities reach unacceptable levels.

Woven Mercerising
Grey knit mercerising has lot of size in the weak liquor and hence the recycled caustic has to be replaced frequently say once in a week Desized mercerising contains relatively lesser impurities and hence can be recycled longer say around 1 – 2 months Bleached mercerising hardly contains any impurities and hence caustic can be recycled for 5 – 6 months without having to replace it.
Yarn mercerising

Denim Mercerising

Weight Reduction machine for Polyester
During weight reduction of polyester the weak liquor of caustic generated can be recycled after separation of suspended impurities and oligomers.Black liquor concentration in case of paper industry where the caustic weak lye from the digester is concentrated. The concentrate can then be taken to either a reboiler or gasifier or a Fluidised bed dryer for further treatment.
Pet jar recycling units where the old pet jar bottles are cleaned with soap and then washed with caustic . The jars after cleaning produce weak liquor which after recycling can be reused .
Alumina production units generate lot of caustic weak lye

Caustic recovery system / caustic soda recovery , have a payback of not above 6 months due to following reasons Reuse of caustic back in system

Here are a few advantages of a UNITOP Caustic recovery Plant over its competitors after studying of which over 150 customers in India and internationally choose us over others.
Energy costs
UNITOP steam consumption is 25% to 30% lower than any other Manufacturer. Considering the fact that the running cost of CRP is almost 3 -4 times the plant cost itself,  UNITOP customer saves money equal to the plant cost every year.Condensate quality
Demister pad arrangement ensures good quality of condensate not over 9pH ensuring minimum loss of caustic through condensate. 

Control Systems
Entire plant operations can be automated and hence the plant can be monitored by a single person.Advanced Plants are equipped with Level, density, pH controllers along with safety modules and PLC controlled operations with SCADA.

Scope of Supply
UNITOP offers the plant on truly turnkey basis with no hidden scopes.Purification systems, pumps, filters are all included in the offer whereas most competitors ask client to buy it as optional accessories or get it manufactured onsite as per their specifications at clients cost.

Life of Caustic recovery Plant
UNITOP considers a higher corrosion allowance and hence designs higher tube thickness ( 1.6 mm ) whereas most competitors consider tube thickness of 1.2 mm.This obviously has higher chances of damages and replacement.

Reliability & Dependability
UNITOP over years of extraordinary services has been able to gain trust of its clients whereby 8 of its customers have placed more than 2 orders with us and 42 customers who have ordered their plants from 2005 -08

UNITOP is so confident of its claims that we have been amongst the first to have provided the caustic recovery plant with a data acquisition system where all the inputs and outputs of the plant are connected via sensors to a computer which not only record all parameters and defaults but also can provide the data either current or history in graphical or text format. This data can be transferred to excel format and the economics of the Caustic recovery Plant can be worked out each day
Anúncios

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