I. Introduction

Sichuan Zizhong County Longsheng Machinery Co., Ltd. has long been committed to the research and development and manufacture of papermaking machinery related technologies. It is a Class B pollution control enterprise of Sichuan Environmental Protection Bureau. It has a number of patented technologies in papermaking black liquor processing and pulping equipment. This paper mainly introduces the black liquor treatment technology.

The problem of papermaking black liquor has always been the number one problem in the papermaking industry, which has long restricted and plagued the development of the paper industry. Although there are many ways and methods at present, such as flocculation, biological methods, acid precipitation and the like. However, it has been proved by practice that there are enterprises that cannot afford huge operating costs, and the process is difficult and cannot operate normally for a long time. In the case of alkali recovery, there is another drawback such as an over-investment and the inability of SMEs to bear. The engineering and technical personnel of our factory, with the support of relevant research institutes and colleges and universities, skillfully use the theory of thermal drying and use physical methods to make the thorough treatment of the black liquor problem in the paper industry become a reality.

This technology belongs to our factory patent (patent number 02221762.2). It has been put into operation in many domestic paper mills. It has been highly appraised by paper owners and environmental protection experts, and has attracted great attention from the government and requires full promotion.

The use of this technology to treat papermaking black liquor is favored because the biggest difference between this technology and the traditional method is that the treatment of black liquor with this technology not only does not burden the enterprise, but also brings good economic benefits to the enterprise. . The lignosulfonate obtained in the black liquor treatment is a chemical primary product and has a wide range of uses. Mainly used for concrete alkaline water agent (annual demand: 1.5 to 2 million tons), oilfield chemicals (annual demand: 800 to 1.2 million tons), industrial dispersant and binder (annual demand: 300,000 to 500,000 Tons), in addition to a wide range of pesticide suspensions, rubber fillers, feed additives and edible fungi, crop growth stimulators, soil amendments, slow-release compound fertilizers, food industry, Xiangjing - vanillin, etc. Industry. And a large number of exports to Europe and the United States and Asian countries. With the increasing use of lignin products and the continuous development of the market, the demand for lignin products in China will continue to expand. It is reported that the annual demand will increase by 20-30%.





Second, technical brief

The basic principle of this technology is to concentrate the raw black liquor of papermaking to a concentrated black liquor containing about 40% of dry solids through an evaporation station, spray it with a special high-speed centrifugal spray device, and the droplets meet the hot air to instantly absorb the water. Evaporation and drying to form a powder to obtain the final product, lignosulfonate (or alkali lignin).


The whole process is completed in one closed pipeline container, no waste gas and no secondary pollution. The system is compact in structure, reasonable in process and reliable in performance. The inner liner is made of stainless steel, which is durable and has high efficiency. It is the green environmental protection channel for the paper industry to use the bamboo, wood and grass papermaking black liquor to produce chemical products, the source of pollution control, benign circulation and scientific ideal.

Third, the process program

1. The steamed boiled slurry is sprayed by pressure, and enters the spray bin. Under the premise of not adding any dilution water, it is spirally conveyed into the high pressure extruder to extract black liquor as high concentration as possible. The concentration of black liquor is about 7-11 Beo, and the extraction rate of single-stage black liquor is 80-85%. (The GHT series high-pressure black liquor extractor produced by our factory has a pulping concentration of 50% and a single-stage extraction rate of 80-85%).

2. The black liquor proposed in the above process is pumped into the evaporation station and evaporated to 25-30 Beo, and the solid content is 36-44%. According to the conditions of each factory, the evaporation method can be selected by itself.

3. The high concentration black liquor is sent to the centrifugal spray drying system to form a powder having a water content of 5 to 10%. That is the finished product.


Black liquor spray drying system lignosulfonate


Fourth, equipment composition

The complete set of equipment consists of cone bottom discharge bin, discharge screw, high pressure extruder, heating pipe, black liquor tank, flame hot blast stove, blower, high temperature fan, soot dust collector, high speed centrifugal sprayer, explosion-proof device, stainless steel drying tower, Hair dryer, storage bin, recycler, receiving box, spray water bath dust collector, high pressure fan, circulating water pump and pipeline, electric control cabinet and so on.

Five, operating costs

Standard coal (4,500 kcal), at 150 yuan / ton;
Electricity is measured at 0.5 yuan / kWh;
The production cost of producing 1 ton of lignosulfonate or alkali lignin is about 500-700 yuan/ton, and 1 ton of lignin dry powder can be obtained for every 10 tons of black liquor (8Beo) (currently the market price of lignin is 1000-1500). Yuan / ton).