New Method of Materials Flow Calculation for Double-String SLCI Type Cement Plant (Part 2: Suspension Preheater and Calciners)

In many industries, energy auditing is important as the basis for controlling processes and designing additional equipment or modifying an existing plant. However, it requires detailed data of the materials flow, which often cannot be determined easily by direct measurement due to high-temperature limitations. This paper presents the second part of an integrated study to perform energy auditing in a separate line and in-line calciners (SLC-I) type cement plant. The second part of this study, as presented in this paper, focused on the materials flow calculation for eight separate cyclones and two calciners. The least square method was employed for solving the obtained overdetermined system equations. Using the operation data from Part 1 of the study, calculation of the detailed materials flow in each cyclone was executed. The results showed that the separation efficiency of cyclones 1A, 2A, 3A, 4A and 1B, 2B, 3B, 4B was 93.86%, 89.80%, 84.41%, 81.98% and 93.96%, 88.70%, 88.53%, 80.72% respectively and the estimated calcination percentage of kiln feed coming out of the ILC and the SLC was 85.3% and 56.3%, respectively. These values are impossible to be measured directly in the cyclones and calciners during plant operation.

New Method of Materials Flow Calculation for Double-String SLCI Type Cement Plant (Part 1: The Whole Clinker Plant)

Materials flow values are instrumental in many industries for controlling and simulating processes, designing new equipment as well as modifying existing plants. They are sometimes impossible to determine by direct measurement in an operating plant due to the very high temperatures. This study attempted to overcome the difficulties associated with this measurement by proposing a new method to calculate materials flow of a double-string suspension preheater type of cement plant with separate line and in-line calciners (SLC-I), with heat balance error less than 1%. This study was divided into two sequential parts, with the first part presented in this paper. The methodology of the first part was to solve the conservation law of the main clinker plant equipment, supported by Bogue’s equation, the heat of calcination, and the thermodynamic properties of the related materials. The least-square method was employed for solving the overdetermined system equations obtained in the second part. The results of the first part were: the ratio of heat formation to specific heat consumption was 52.13% (> 50%), and the gas exhausted from the plant yielded more than 117 MW heat equivalent, which can potentially be recovered for electricity production.

BURDEN MATERIAL DISCHARGE FROM THE ISOLATION BELL OF THE BLAST FURNACE CHARGING AREA

Blast furnace practice has been remaining the most suitable one in the steel production route. A rather large amount of blast furnaces (BF) is equipped with bell-like charging equipment. The discharge capability of such equipment has a drastic influence on the parameters of the charging operations and blast furnace driving rates. The charging features regulate in many cases burden materials descend and the parameters of the BF smelt. In relation to the mentioned, it is revealed that to determine the volume of the burden materials flow passing through the isolation bell of the BF charging area is an urgent scientific and engineering problem. A number of publications is devoted to the problem how to define the burden materials flow coming from the large bell. Most of these studies are grounded on the expressions by prof. Zenkov. However, there is a drawback apparently present in these findings and it can be expressed as the lack of the complex approach to incorporate such parameters as the material type, its granulometry and the geometry of the isolation bell outlet hole. The aim of the current research is to reveal the analytic dependence capable of determining the volumetric flow of the burden materials passing through the hole of the large bell. Thus, possessing the data on the burden materials flow and the geometry of the isolation bell outlet hole, one can determine the initial conditions for developing the trajectory of burden materials movement within the top area of the blast furnace. Moreover, the method proposed with the current publication permits determining the actual aggregate size of the burden materials coming to the BF top charge through the data of burden materials volumetric flow. Further, the actual size of the material particles being charged can be derived from the dependences presented in this work and this, in its turn, influences the permeability of the burden materials column for gases at a given point of BF top radius. Taking these data into account, the real opportunity emerges for an on-line correction of the BF drive by incorporating the certain on-line conditions of BF smelt. The results of the findings reported in this article are to be utilized for improvements on the automation system of blast furnace charge control.