Very often, we are discussing the topic: thermal oil heaters (TOH) or steam boilers – which is better? This question is especially relevant when you have to choose a development concept for your company fuel and energy complex, and accordingly, identify the main process equipment to be used at a new plant which is often the case in the early stages of a new project discussion and estimation of associated construction budget.
We took the construction of a new plywood mill with the production capacity of 120,000 m3/year as an example and prepared an analysis of technical solutions based on the construction of a mini HPP on the basis of steam boilers and turbo-generator as against the use of thermal oil heaters (TOH). As a manufacturer of both steam boilers and thermal oil heaters, we tried to assess these two options and clarify the advantages of the construction of a mini HPP running on steam, even though it requires a slightly greater initial capital investment. Both options are based on the concept of "turnkey" supply of all the necessary basic and auxiliary equipment, including buildings and constructions.
Analysis of the plywood mill heat balance suggests that to ensure normal technical operation of process equipment, as well as to accommodate the winter-period heating loads, the plant requires 28 MWH of heat during summer, and up to 43 MWH in winter. Thus, to satisfy the plant needs, at least three TOH with a heat capacity of at least 14 MWH each (total 3х14=42 MW) are required. Moreover, the load ratio of one of these TOH will be equal to 0.5, as it will only be used in wintertime. Application of a larger number of TOH with lower capacity leads to a significant increase in the initial investment amount, as these units do not carry the added value (not paid back), and furthermore, to the reduction of the effectiveness of the plywood mill construction project in general. We would like to point out the following flaws inherent in the construction of the TOH, which do not allow us to recommend this solution for implementation:
We believe that the construction of a mini HPP on the basis of two WELLONS.RU steam boilers producing 25-30 MTH of steam with the characteristics of 40 bar/440°C, and 7 MWH Siemens turbo-generator is an effective solution. This option carries a greater added value, represents a profitable project itself and improves the financial performance of the plywood mill construction project in general. For example, the implementation of the project under this scheme allows to generate up to ~ 54,600,000 kW/year, or to gain EBITDAextra revenue in the amount up to 260 mln rubles a year on the average. The results of feasibility analysis of additional investments to mini HPP as compared with TOH option are shown in the table below:
We would like to emphasize the advantages of building a mini HPP that allow us to recommend this solution for implementation:
The best solution, the most rapid return on investment in relation to other possible solutions for waste disposal (chipboard, MDF, pelleting, briquetting, etc.). Smaller investment volume, independence from the market of plate board materials.