Mechanical Plant Heat Supply Systems

Contents

Introduction

Heat supply is one of the main subsystems of energy. About 1/3 of all primary fuel and energy resources used in the country are spent on heat supply to the national economy and the population. Therefore, from an economic point of view, a very important problem was the rational use of fuel in heat supply systems, the engineering of which could have a noticeable economic effect. The directions of co-improvement of heat supply systems are concentration and combination of heat and electric energy production (heating) and price trawling of heat supply. However, over the past few years, there have been several hundred trends towards decentralized heat generation, which was manifested in the co-building of smaller heating circuits and block boiler houses

The main purpose of the heat supply systems is to provide these climatic conditions in the premises of buildings. When designing heat supply systems for industrial enterprises, one of the most important is the stage of calculating their heat loads. Heat consumption by enterprises in all industries was highly unequal. By the nature of the flow over time, the heat loads of any enterprise are divided into two groups: seasonal and year-round. To cover seasonal loads, heat is released during a season, and the nature and nature of their changes depend mainly on climatic conditions: ambient air temperature, wind direction and speed, etc. Seasonal heat consumers are heating, ventilation (heated air in calorifers) and air conditioning systems. To cover year-round loads, heat is released throughout the year. These include process heat consumers and hot water supply systems for utility consumers. The magnitude and nature of the heat transfer schedule for technological needs depends on the profile of industrial enterprises and the mode of their operation. The magnitude and nature of the hot water supply load schedule depends on the number of workers in the plant, the intensity of the work and the nature of the heat in the work area

The calculation of thermal loads of an industrial enterprise includes the subsequent execution of the following stages:

1) selection of initial data and reference materials according to the task for heat supply system design;

2) determination of the calculated (maximum) heat consumption for each type of heat consumption of individual workshops and the entire enterprise;

3) determination of the average for the heating period and annual costs of the heat lot for each type of heat consumption for the entire enterprise, taking into account its mode of operation;

4) establishing the nature of changes in heat loads during the day and year, constructing annual schedules of their duration;

5) determination of annual heat consumption of an industrial enterprise and construction of a total heat consumption schedule

Heat supply systems include three main links: a heat source, heat pipelines (heat networks) and heat consumers. The heat demand of heat-using consumers is not constant and varies both depending on meteorological conditions and on a number of other factual conditions. The change in the amount of heat supplied to consumers according to their heat consumption schedules is called heat release control. Regulation improves the quality of heat supply, reduces the re-consumption of thermal energy and fuel

In district heat supply systems, the heat source and its consumers are located separately, therefore, heat transfer from source to consumers is carried out through heat networks, the length of which can reach tens of kilometers with the attendant complication of their schemes. In this regard, serious attention should be paid to the proper and rational design and operation of heating networks, since the reliability and cost-effectiveness of the entire district heating system largely depends on this. One of the most important sections of the design and operation of thermal networks is their hydraulic calculation. As a result of the hydraulic calculation, the following are determined: diameters of pipelines, pressure drop along the length of the pipeline, pressure at various points of the network; all points of the network-to-consumer system are linked in order to ensure allowable pressures and required pressures in the network and subscriber systems

One method of increasing efficiency of operation of heat supply system of industrial enterprise is reduction of heat losses during transportation of heat carrier to consumers. In this regard, the role of thermal insulation of network pipelines as a factor contributing to fuel economy, as well as providing the necessary temperature regime in isolated systems, is greatly increasing. The results of thermal calculation are: selection of thermal insulation material; determination of heat insulation layer thickness; determination of air temperature in the channel; calculation of heat losses through insulation and determination of network water temperature decrease along the pipeline length

Centralized heat supply of an industrial enterprise can be carried out from thermal power plants (CHP) or central boiler houses. With moderate heat loads, heat supply from the boiler house was preferable. Hot water boiler houses are often built in newly built-up areas, when the commissioning of a CHP or main heating networks is far from the time from the commissioning of heat-supplied facilities in the area. When the CHP is activated, hot water boilers are used as backup or peak heat sources. Steam boilers can be used to provide heat with both steam and hot water. Heating of network water by steam is carried out in steam-water heaters

Introduction - 1 -

I. Determination of heating costs - 6 -

1. Calculation of heat consumption for heating of workshop No. 9 - 6 -

1.1. Calculation of heat losses through the enclosures of workshop No. 9 - 7 -

1.2. Calculation of heat flow rate for infiltrating air heating - 12 -

1.3. Calculation of heat emissions in workshop No. 9 - 12 -

1.4. Determination of the estimated heat consumption for heating of workshop No. 9 - 12 -

2. Calculation of heat consumption for heating of workshops No. 2, 3, 4 and 5 - 13 -

II. Determination of heating costs for ventilation - 14 -

1. Calculation of heat consumption for ventilation of workshop No. 9 - 14 -

2. Calculation of heat consumption for ventilation of workshops No. 2, 3, 4 and 5 - 14 -

III. Determination of heat costs for hot water supply - 15 -

IV. Determination of heat consumption for technological needs - 16 -

V. Calculation of annual heat costs for certain types - 18 -

1. Calculation of annual heat consumption for heating - 18 -

2. Calculation of annual heat consumption for ventilation - 19 -

3. Calculation of annual heat consumption at HVAC - 20 -

4. Calculation of annual heat consumption for technological needs - 20 -

VI. District heating regulation - 20 -

VII. Hydraulic calculation of the water heating network - 25 -

1. Calculation of the main highway - 27 -

1.1. Calculation of section G-5 - 27 -

1.2. Calculation of section B-G - 27 -

1.3. Calculation of section B-C - 28 -

1.4. Calculation of section A-B - 28 -

1.5. Calculation of O-A section - 29 -

2. Calculation of branches - 30 -

2.1. Calculation of section G-4 - 30 -

2.2. Calculation of section B-3 - 30 -

2.3. Calculation of section B-2 - 31 -

2.4. Calculation of section A-9 - 32 -

VIII. Hydraulic calculation of steam heating network - 33 -

1. Main line calculation - 34 -

1.1. Calculation of section G-5 - 34 -

1.2. Calculation of section B-G - 35 -

1.3. Calculation of section B-C - 36 -

1.4. Section A-B calculation - 37 -

1.5. Calculation of area O-A - 39 -

2. Branch calculation - 40 -

2.1. Calculation of section G-4 - 40 -

2.2. Calculation of section B-3 - 41 -

2.3. Calculation of section B-2 - 42 -

2.4. Calculation of section A-9 - 43 -

IΧ. Thermal calculation of the water heating network - 44 -

1. Calculation of heat insulation layer thickness - 44 -

2. Calculation of heat losses through the thermal insulation structure - 46 -

3. Calculation of heat losses with network water leaks - 0 -

Χ. Calculation of boiler room thermal diagram - 1 -

1. Calculation of the hot water part of the boiler house - 1 -

2. Calculation of boiler room steam part - 2 -

3. Calculation of water-water cooler of makeup water - 5 -

Appendix 1......................................................................................................

Appendix 2......................................................................................................

Appendix 3......................................................................................................

List of literature - 8 -