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Chemical Recovery Boilers in Paper Plants

Date: 05-15-2017 Author: ailsa from ZG boiler

The paper that we use in day to day life is made from wood. Wood is cooked in digesters using sodium salts. These salts are recovered in the process by a chemical recovery boiler. Earlier roasters were used and were replaced by recovery boilers which are much more energy efficient.

The Process

In a pulp and paper plant the sodium salts used for extracting the lignin from wood during cooking have to be recovered to make the process viable. A cooking liquor recovery cycle retrieves white liquor for the cook from the black liquor spent chemicals obtained from the pulp wash. Weak black liquor containing about 15% inorganics and the lignin organic is concentrated in multiple-effect evaporators (MEE) to about 50% strong black liquor. Due to liquor characteristics, further concentration is often better done in a cascade evaporator where hot gaseous stream from a boiler contacts the liquor. Cycle make-up chemicals, usually salt cake, are added to the resulting 68% heavy liquor. At this concentration, the heating value is high enough to provide self-sustaining combustion with air to evaporate the remaining water, provide heat of reduction for chemical recovery, and to provide additional heat liberation to warrant heat recovery in the steam generating sections of the recovery unit.

Chemical Recovery Boilers in Paper Plants.jpg

Functions of Chemical Recovery Boilers

1 To recover the inorganic chemicals from black liquor
2 To produce high pressure and high temperature steam for captive power generation and also provide steam for use in Pulp and Paper mill operations.

Pulp mill operations totally depend upon the chemical recovery boiler. Generally, each paper mill is linked up with one recovery boiler and hence its availability and efficient operation are of utmost importance. Unlike other types of boiler in chemical recovery boiler the combustion takes place in reducing atmosphere and with coarser particle sizes.

Types of Chemical Recovery Boilers.

Depending upon black liquor concentration available from MEE, following types of chemical recovery boilers can be chosen.
1.Conventional units having direct contact evaporator (like cascade evaporator) wherein black liquor at 45 to 50% from MEE is concentrated to 62% to 70% solids before firing into furnace.
2.Large economizer units. In these units, black liquor at 62 to 70% from MEE is directly fired in to the furnace. In this case a vertical tube extended surface economizer replaces the direct contact evaporator.

Salient features of a Chemical Recovery Boiler.

Fully welded furnace waterwall construction with no refractory on vertical waterwallls
Decanting hearth with multiple smelt spouts. Suspension firing of black liquor with multiple black liquor guns
Properly proportioned drying, reducing, and oxidizing zones with tangential concentric air system above the black liquor guns
Widely spaced tangent tube superheater with flexible connectors and steam cooled spacers
Single pass baffle-less boiler bank. Vertical straight tube economizer
Twin wheel cascade evaporator system. Concrete cased electrostatic precipitator with collecting electrode of COR-TEN steel
Forward curved bladed radial induced draft fans
High energy arc ignitors with visible light scanners for start up oil burners
Furnace safeguard supervisory system
Fully automatic soot blower control system

Keyword: Industry steam boiler,Chemical Recovery Boilers, Boilers in Paper Plants

Source: http://www.zgsteamboiler.com/solution/Chemical-Recovery-Boilers-in-Paper-Plants.html

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Packaging & Delivery

Packaging Detail:Wooden box package of Chemical Recovery Boilers in Paper Plants

Delivery Detail:20-40 days after payment

Industrial Steam Boiler Packaging & Delivery

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Why choose ZG as industrial steam boiler manufacturer?

We have over 70 years' experience of industrial steam boiler and autoclave, and we have a professional installation and after-sales staff for products.Take advantage of the most economical way to improve efficiency and operating flexibility, Get substantial savings on your fuel costs,Reduce all emissions for each K/W of electricity generated, including CO2.

How about the quality of Chemical Recovery Boilers in Paper Plants?

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Our industrial steam boiler manufactured strictly according to national and international standard. our products have approved ASME, IBR, ISO9001-2008, etc

All our company's products are 100% factory inspected to ensure the high quality.

We provide one year quality warranty service, please rest assured purchase.

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ZG service ensures that this will not happen. During installation of industrial steam boiler, 1-2 experienced engineering and technical personnel will be sent for the site representative for technical tests and installation instructions free of charge; processing the various problems arising in the course timely while installing.

Industrial Steam Boiler Company Information--- ZG Boiler

Established:In 1945

Number of Employees:above 1500 People

Our products:industrial horizontal steam boiler and hot water boiler(biomass boiler, gas boiler, oil boiler, coal boiler, etc), CFB boiler, power plant boiler, waste heating recovery boiler, Pressure Vessel(AAC autoclave, Curing tank,etc )

Factory Size (Sq.meters):400,000 square meters

Factory Location:Factory 1: Zhengzhou,,Henan, China. Factory 2: Xingyang,Henan,China

Number of R&D Staff:376 people

Our Trade & Market

Export Percentage:30-40%

Total Annual Sales Volume:US$100 Million

Main Market:South America(Colombia, Venezuela, Guyana, Suriname, Ecuador, Peru, Brazil, Bolivia, Chile, Paraguay, Uruguay, Argentina and French Guiana), North America(Bahamas, Canada, Costa Rica, Cuba, El Salvador, Guatemala, Honduras, Haiti, Jamaica, Mexico, Nicaragua, Panama), Eastern Asia(Mongolia / Russia / North Korea / South Korea / Japan), Oceania(Australia, New Zealand, Fiji), Mid East(Bahrain, Egypt, Iran, Iraq, Israel, Jordan, Kuwait, Lebanon, Oman, Qatar, Saudi Arabia, Syria, UAE and Yemen, Palestine, Algeria, Libya, Morocco, Tunisia and Sudan, Mauritania and Somalia), Africa(Egypt, Sudan, Libya, Tunisia, Algeria, Morocco, Ethiopia, Somalia, Kenya, Tanzania, Sierra Leone, Liberia, Cote d'Ivoire, Ghana, Togo, Niger, Nigeria, Cameroon, Gabon, Congo (Brazzaville), Zambia, Zimbabwe, Angola, Mozambique, Botswana, Namibia, South Africa), South Asia(Nepal, Bhutan, India, Pakistan, Bangladesh, Sri Lanka, Maldives) Southeast Asia(Vietnam, Laos, Cambodia, Thailand, Myanmar, Malaysia, Singapore, Indonesia, Brunei, the Philippines, East Timor) Domestic Market(China)

Source: http://www.zgsteamboiler.com/solution/Chemical-Recovery-Boilers-in-Paper-Plants.html

Pre:  Steam Boiler for Olive Processing

Next:  Wood Fired Boiler for Laundry and Dry Cleaning Operation

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