Improve the quality of tar ammonia under the existing process
l increase tar production by more than 2%
l Improve wastewater (COD) quality to meet environmental protection requirements
l reduces the 50% of tar moisture (intermediate tank and storage tank)
l Purify gas, which is beneficial to the deep processing of gas
l Significantly reduce the deposition of ammonia water heat exchangers, ammonia washing towers and ammonia distillation towers and the corresponding cleaning frequency
l Significantly reduce the tar deposition of the primary cooler, increase the heat exchange rate of the primary cooler, and reduce the corresponding cleaning frequency
l Reduce the 75% effect of the gas collection pipe spray blockage, and reduce the corresponding nozzle cleaning frequency and intensity
l Reduce the gas outlet temperature of the gas collector by about 0.5-2°C.
the special metering pump provided by xingke company is directly added to the system before the circulating water pump. according to the different production process, the addition amount is about 200ppm-300ppm, and the addition amount is adjusted at any time according to the site conditions
Importance of quality management of tar and ammonia water
ammonia and tar are produced at the same time, then they are treated at the same time, and then they are treated separately after the gas-liquid separator, but because of the design of the gas washing operation, they are combined in many processes. This characteristic, which is sometimes separated and sometimes combined, causes many problems for the entire production process.
in order to meet the requirements of environmental protection emission and ensure the requirements of tar ammonia separation process and tar recovery process, coking plants must pay attention to the management of ammonia water and tar quality. Strict and correct ammonia tar quality management can reduce operating costs and increase economic benefits.
3.1 ammonia water
even if all the tar in ammonia water is separated, the nature of ammonia water itself will still have a direct impact on the production process and operation cost. We believe that clean ammonia water will still cause corrosion and scaling in the production system.
the main cause of corrosion caused by ammonia water is due to the presence of ammonia, cyanide, H2S,CO2 and other pollutants in ammonia water. Basically, there are few measures to prevent corrosion. Theoretically speaking, there should be no calcium in ammonia. However, in practice, a small amount of calcium (<10ppm) is often detected in ammonia water. The reason for the existence of this calcium mainly comes from two aspects, one is the wastewater discharged from other system operations, and the other is because of environmental protection requirements. The wastewater generated at various stages must be treated during the coke oven gas washing process. When the calcium ion content exceeds 10ppm, the internal scaling trend of the system will be significantly enhanced, and the corresponding wastewater treatment cost will also be greatly increased. The increase of calcium ions will also reduce the cooling effect of the system, reduce the quality of circulating ammonia water, and reduce the yield of coke oven gas by-products, resulting in an increase in operating costs. Therefore, if the calcium content in the ammonia system increases, the source of calcium ions must be identified first, and then the impact on the system and process due to the presence of calcium ions must be eliminated or reduced as much as possible.
On the other hand, although clean ammonia water should not contain tar, tar is often present in actual operations. At a lower tar content (<25ppm), the tar in ammonia will not have a great impact on the process and operating costs. If the tar substance is controlled to less than 100ppm, the negative impact on the production process is acceptable. However, in most ammonia tar operation practices, the tar content is much higher than this value, a bit at 200-300ppm, and the height even reaches 2000-3000ppm. At such a high tar content, the deposition caused by the combination of tar and suspended matter in the system will affect the various processes of the gas cleaning operation. It not only directly reduces the cooling efficiency of the system, greatly increases the operation and maintenance cost of the system, but also reduces the yield of coke oven gas by-products, aggravates the corrosion and deposition of system pipelines, and also brings hidden dangers of environmental protection.
tar is a valuable by-product of the coking process. Therefore, the quality of tar produced in the recovery process will have a great impact on the efficiency of the coking plant.
The quality of tar is mainly judged by the following aspects:
3 toluene insoluble or quinoline insoluble
The problem of moisture mainly occurs in the tar treatment process or the coking operation process, of course, it may also be the result of the joint action of the two.
The problem of toluene insoluble/quinoline insoluble and ash mainly occurs during the coking operation, and may also be caused by improper operation of some equipment.
4 Strengthen quality management of tar ammonia water
Generally speaking, tar ammonia systems are designed with appropriate operating procedures and treatment equipment. If the coking process and gas cleaning process are properly operated, the quality of tar and ammonia should be sufficient to reduce operating costs and recover by-products as much as possible. However, in the actual operation, the quality of tar and ammonia will always fluctuate, which is somewhat different from the expected target of the coking plant. Eliminating or reducing these fluctuations is a key factor in strengthening the quality management of tar ammonia.
Adding suitable equipment can achieve the purpose of producing high-quality tar and ammonia, but this investment is obviously uneconomical for coking plants. Therefore, the coking plant can only operate strictly according to the standards on the basis of the existing equipment, so as to ensure the improvement of the quality of the final products as much as possible.
Like any process treatment, the important key point of tar ammonia quality management should be placed upstream of the process side. Only in this way can the downstream process benefit from these process improvements. The improvement of each process will form a synergy, and the entire production process will benefit from this systematic improvement, thus achieving a virtuous circle.
We usually solve the problem in the following three aspects, and usually we consider the means of quality according to their order:
Although not all operations will be affected by the three factors listed above, the problems must be evaluated in the above order, because only in this way can a correct evaluation of the system and process be obtained to achieve the desired results.
In short, the correct management of tar ammonia quality can reduce operating costs, improve economic benefits, and ensure that production operations meet environmental protection requirements.
5 chemical working mechanism
The role of this chemical is a demulsifier and binder reduction.
tar and circulating ammonia water enter the ammonia water tar separation tank in an emulsified state. If there is no other solution that can stabilize this emulsified state into the large tank, ammonia and tar can be easily separated in the large tank according to their respective physical characteristics, and the separation speed is very fast. However, there is still an emulsification layer containing tar, pulverized coal, coke powder and ammonia in the large tank. If the residence time is long enough, these substances can continue to be separated, but it is impossible to provide sufficient due to the requirements of the production process in the actual operation. Therefore, some impurities in the incomplete emulsion often leave the tar ammonia tank together with ammonia and enter the ammonia spray system. At the same time, the waste liquid leading to the ammonia tar separation tank will also maintain the emulsified state of the ammonia tar.
this product is a tar dehydrating agent and an excellent binder. it will form a film on the surface of tar, increase the fluidity of tar, and greatly reduce the adhesion of tar.