I. characteristics of gasified CWS:

CWS is a kind of pulverized coal mixed with water with a certain particle size and gradation. It has certain stability and fluidity. It can be pumped and atomized combustion slurry coal products like heavy oil. CWS technology is an important part of clean coal technology. CWS has a complex mechanism of slurry formation and many influencing factors, involving in the disciplines of coal chemistry, particle science, colloid science, organic chemistry and rheology.

The CWS used for gasification are generally controlled at: concentration between 58% and 65%, viscosity between 400 and 1000mpa.s, and stability within 24 hours. Executive standard: GB/T 31426-2015

Factors influencing the slurry formation of CWS

1. Properties of coal

The lower the coal rank, the higher the internal water content, the higher the ratio of coal type 0 to C, the more hydrophilic functional groups on the coal surface, the more developed the pores, the smaller the wearability index HGI value, the more soluble high-price metal ions in the coal, the more difficult the coal pulping.

2. Influence of particle size level pairing to slurry

Appropriate grinding equipment and pulping technology are selected according to the properties of raw coal. Reasonable size grading can achieve higher accumulation efficiency, reduce the space between particles and improve the coal slurry concentration. The gasification slurry is usually divided into two peaks or multiple peaks.

3. Influence of dispersant on the formation of pulp

Coal is a kind of macromolecular aromatic compound with complex structure. The surface of these organic matters is strongly hydrophobic, not easily wetted by water, and the fine coal powder has a large specific surface area. In the water, it is easy to spontaneously coalesce with each other, so that the coal particles and water cannot closely combine into a kind of slurry, and only a kind of wet mud mass can be formed when the concentration is relatively high.

In pulping, a small amount of dispersant must be added to change the surface properties of coal particles, so that the surface of coal particles is tightly surrounded by dispersant molecules and hydrating film, and the coal particles are evenly dispersed in water to prevent coalescence and improve the fluidity of CWS. The physical and chemical characteristics of coal surface vary greatly, and the appropriate dispersants vary from coal to coal.

4. Effect of stabilizer on the formation of slurry

Coal slurry is a kind of solid and liquid two-phase coarse dispersion system, easy to precipitate, a small amount of stabilizer can improve the stability. Therefore, CWS has the rheological characteristics of shearing thinness. In other words, CWS have a high viscosity when stored in static storage, and the viscosity can drop down rapidly after flowing. Allow the sediment to have a soft structure to prevent the formation of irreversible hard precipitation.

5. Effects of temperature, PH value and slurry preparation wastewater on slurry formation

Influence of temperature: increase of temperature, accelerated adsorption rate, beneficial to pulping. However, the viscosity decreases, the sedimentation rate increases and the stability decreases.

Influence of PH value: when PH value is 8 to 10, coal slurry shows relatively good slurry performance. In this range, PH value increases and liquidity becomes better.

Influence of pulping wastewater: the influence of pulping wastewater needs to be verified by pulping test.

Iii. Introduction of water slurry additives

1. The research on pulping process and equipment is more complete and the technology is relatively mature.

2. Lack of theoretical knowledge of additives, especially dispersants, and insufficient research on the mechanism of micro-molecular structure.

3. There are nearly 100 kinds of coal suitable for gasification of CWS in China, lacking dispersant and special molecular structure database for matching.

4. Low average coal slurry concentration, high gasification coal consumption and oxygen consumption, and low effective gas content in product syngas.

5. There are few high level gasification high-efficiency CWS additives in China, especially low-rank coal high-efficiency additives.

Iv. Research and development content of CWS far east slurry dispersant

In view of the three main factors affecting the quality of coal water slurry of coal characteristics, particle size distribution and additives, the division in the far east for coal water slurry gasification raw material surface physical and chemical properties of coal, from the perspective of the molecular structure, through a large number of experiments and tests, synthesis of the polymer compound with economy, and for each kind of coal water slurry gasification raw coal, research and development of special high efficient additives, the additive of raw coal has good matching performance. The database of the special additive molecular structure of nearly 100 kinds of coal of coal water slurry gasification raw material has been completed, which provides the comprehensive and fast additive optimization formula for the users of coal water slurry gasification in China, and assists the users to improve the coal slurry concentration and reduce coal and oxygen consumption. Without changing the pulping process, the average concentration of coal slurry can be increased by more than 2%.

V. data cases of pulp performance test

NIMTE

Ningbo Institute of Material Technology&Engineering. Chinese Academy of Sciences.

The Test report series No: the 2018-03-06-01

Coal additive proportion/actual dry solids / % % dry coal coal/g/g dock planner the concentration of the actual water / / % % actual concentration viscosity/cp/s liquidity discount rate of water stability

Huang Tao

Leguezhong ke far east 1.99.12 193.7 104.94 64 64.63 358.9 22 0.3a 0.03 soft

Jinjiatan zhongke far east 1.5 96.38 199.21 99.43 64 64.27 379.9 15 3.2 A 0.01 soft

The quality of gasified CWS can be stable to the following indexes:

1. Average concentration of CWS: 63 + 1%;

2, the average viscosity of coal water slurry (25 ℃, 100 s - 1) 600 mpa, s or less;

3. Stability of CWS: greater than or equal to 24 hours;

Vi. Technical advantages and characteristics of zhongke and the far east

1. The average concentration of CWS is high;

2. Small amount of addition, usually 1.5-2 parts per thousand (dry base);

3. Low chlorine ion and sulfate ion additives to eliminate pollution of grey water system;

4. High match with low-rank coal (long-flame coal and non-stick coal);

5. Moderate average coal slurry viscosity, low transport consumption, good atomization effect, beneficial

Optimize the process and extend the service life of the equipment.

Vii. Index of ZK series additives of zhongke far east

Project indicators

Appearance black brown solid powder

Water content (%) is less than or equal to 5.0

Solid insoluble matter (%) is less than or equal to 2.0

10% aqueous solution has a PH greater than or equal to 8.0