Make potassium nitrate production less "drinking water" - a new process for water saving and emission reduction of potassium nitrate production by ion exchange method

　　Tianji Coal Chemical Group Co.
, Ltd.
and Tianji Group Potassium Salt Co.
, Ltd.
innovatively developed a new process for producing potassium nitrate by ion exchange method, which saves water and reduces emissions.
The craft "rejuvenates" and was selected into the "Petrochemical Green Craft Directory (2021 Edition)"
.

　　Water consumption and return water is a problem

　　"Green chemical industry, cleaner production" is a major theme of the high-quality development of the modern chemical industry
.
However, the traditional production process of potassium nitrate, an important agricultural fertilizer raw material, consumes a lot of water and discharges a large amount of sewage
.
The traditional potassium nitrate production process adopts the original ion exchange method.
There are 7 stages in a cycle, producing 1 ton of product.
Only the third stage receives ammonium chloride and the seventh stage washing process consumes 43 tons of fresh water, and the whole process is discharged.
The amount is about 44 tons,

　　In order to achieve no external discharge of waste water, enterprises will reuse waste water
.
However, the reuse of wastewater has produced three major problems: one is to ensure that the reuse of wastewater will not cause too much adverse impact on the system operation, and at the same time to ensure that all wastewater is reused, there is a contradiction between the two; The system is unbalanced to a certain extent, which reduces the production of potassium nitrate; third, the content of dialysis ammonium and dialysis potassium increases, which not only affects the normal operation of the system, but also causes fluctuations in product quality
.

　　Improve the process to overcome difficulties

　　In order to solve the above problems, the technical team has determined the direction of technical transformation after many discussions and practiced it in the production plant
.
Through multiple process adjustments, the new process realizes that wastewater is not discharged and recycled in stages, creatively solves the problems of large wastewater discharge and excessive discharge in the traditional process, reduces the consumption of fresh water, and finally realizes no external discharge of wastewater, The system is fully utilized
.

　　The new potassium nitrate production process they developed adjusted the original 7 stages to 6 stages, and cancelled the fifth stage of the traditional process, that is, the ammonium nitrate stage was directly carried out after the second backwash
.
In this way, the amount of waste water is reduced, the water balance problem is solved, the process flow is shortened, and the output of potassium nitrate is improved
.
The new process also divides the wastewater generated in the process into two categories: storage tank wastewater and wastewater tank wastewater for recovery and recycling
.
After the process is implemented, 10 tons of waste water can be recovered less in each complete cycle, and the recovered waste water can also fully meet the needs of exchange water
.
At the same time, as the amount of wastewater in the process decreases, the receiving concentrations of potassium nitrate and ammonium chloride also increase
.
At the same time, the new process also adopts three-effect evaporation, making full use of process steam to preheat the material, shortening the evaporation time and greatly reducing the amount of primary steam
.

　　In addition, during the development and commissioning of the new process, the technical team also solved several technical difficulties
.
By adjusting and determining new analysis indicators and strengthening process analysis, they solved the problem of affecting resin regeneration after wastewater recycling; by increasing the concentration of raw material solution according to changes in ambient temperature, shortening the time for ammonium and potassium loading, and making the total operation cycle of the ion exchange column Measures such as meeting production needs have solved the problem of prolonged receiving time and increased process condensate affecting production load; by increasing the concentration of raw materials, controlling the flow rate and time of backwash 1 and backwash 2, reducing the amount of water inflow and drainage, and by using condensation The liquid preheating material reduces the temperature of the condensate to meet the system requirements, which solves the problem of water balance; by determining the maximum limit of dialysis ammonium and dialysis potassium, and adding auxiliary materials, the problem of high dialysis ammonium and dialysis potassium concentration is solved; By replacing related equipment, pipes and materials, the problem of increased corrosion of related equipment after wastewater reuse has been solved
.

　　Water saving and consumption reduction

　　In terms of operating costs, taking the annual output of potassium nitrate of 7,637.
9 tons as an example, the new process consumes 0.
75 tons of potassium chloride per ton of raw materials, which is 0.
12 tons less than the traditional process.
It is estimated that the annual cost saving is 2.
118 million yuan; 10,000 tons, a reduction of 305,300 tons compared with the traditional process, and a cost saving of 1,178,400 yuan
.

　　In terms of production energy consumption, the new process consumes 3.
47 tons of steam per ton of product, which is 4.
52 tons less than the traditional process
.
In addition, after the implementation of the new process, the pollution of the water body by the device is completely eliminated, which can reduce the discharge of 267,300 tons of waste water every year, and realize a profit of 608,100 yuan
.

　　By strengthening the control process and multi-stage concentration and emission reduction, the new process increases the output of the by-product ammonium chloride, reduces the production cost, and further improves the market competitiveness
.
The process has also won the China Petroleum and Chemical Industry Patent Award Excellence Award, and the third prize of nitrogen fertilizer and methanol industry technological progress awards
.

　　(This series ends here)