Scheme of calculation of heat supply of industrial area

Contents

INTRODUCTION

1 CLIMATOLOGICAL DATA OF HEATING AREA

2 CALCULATION OF HEAT LOADS OF INDUSTRIAL ENTERPRISES AND RESIDENTIAL AREAS

3 CONSTRUCTION OF ANNUAL SCHEDULE OF HEAT CONSUMPTION FOR HEATING, VENTILATION AND HOT WATER SUPPLY

4 PLOT OF CENTRAL QUALITY REGULATION OF HEATING LOAD

5 SELECTION OF HEATING NETWORK ROUTE AND PROFILE

6 HYDRAULIC CALCULATION OF WATER HEATING NETWORK

7 HYDRAULIC CALCULATION OF STEAM LINES AND CONDENSATE LINE

8 CONSTRUCTION OF PIEZOMETRIC PLOT OF WATER THERMAL NETWORK

9 SELECTION OF SUBSCRIBER CONNECTION SCHEMES TO WATER HEATING NETWORK ACCORDING TO PIEZOMETRIC DIAGRAM

10 SELECTION OF MAINS AND MAKEUP PUMPS

11 SELECTION OF THERMAL PIPELINE INSULATION TYPE AND THICKNESS AND DETERMINATION OF HEAT LOSSES BY PIPELINES

12 CALCULATION OF HEAT CARRIER TRANSPORT ECONOMY

CONCLUSION

LIST OF SOURCES USED

Introduction

Heat supply is an activity for the production, transfer, distribution, sale to consumers of thermal energy (power) and coolant.

A set of technical devices that provide heat supply to consumers is called a heat supply system.

Heat supply can be carried out from centralized (DC) and decentralized (DC) heat supply systems.

Centralized heat supply of consumers is carried out from heat sources combined for parallel operation by extended heat networks.

The process of supplying consumers with heat is possible from any heat-generating plants (CHP, industrial and heating boiler houses, heat pumps, GTU-CHP, PSU-CHP, solar collectors).

The production of several types of products using one source resource is called cogeneration (combined generation), a typical representative of cogeneration is heat generation.

Heating is the process of simultaneous heat release from the extraction of CHP turbines and the production of electricity at this heat release.

Heat supply to consumers from the CHP has a number of advantages and disadvantages compared to heat supply from the boiler house.

Advantages of heat supply from CHP:

Fuel economy at the CHP;

At the CHP, more advanced highly automated power boilers capable of burning lower-quality fuels;

The efficiency of CHP power boilers is higher than that of boilers.

Disadvantages of heat supply from CHP:

The difficulty of choosing a site in the city for the construction of a CHP;

Increase in fuel delivery;

Specific capital expenditures in power boilers at the CHP;

Significant capital costs in heat networks, high accident rate due to the large length of heat networks from CHP to heat consumers and large heat losses in heat networks.

Climatological data of heating area

Heat supply of the industrial district is carried out from CHP No. 3. In the heat supply system of subscribers, which provides a heat load for heating, ventilation and hot water supply, water is used as a coolant. The heat supply system is closed, double-tube. The regulation of heat production is adopted central, high-quality in terms of heating load. To cover the process load, a steam line was supplied to industrial enterprises.

Hydraulic calculation of water heating network

Hydraulic calculation is one of the most important sections of thermal network design. Its task includes: determining the diameters of pipelines, determining pressure losses (head); setting pressure (head) values at different points of the network, linking all points of the system in static and dynamic modes to ensure permissible pressures and required pressures in the subscriber network.

Piezometric plot of the water heating network

When designing and operating branched thermal networks, a piezometric graph is widely used, on which the terrain, the height of the connected buildings, the head in the network and the head at any point of the network are applied on a specific scale.

The piezometric graph is plotted as follows. Axis of network pumps at station is taken as origin of coordinates. Taking this point as a conditional zero, we build a terrain profile along the route of the main highway and by characteristic branches. On the terrain profile in scale, the height of the attached buildings is applied (accept

Ndd = 10... 15 m). Previously, the pressure on the suction side of the pumps Nvs is taken to be 15... 20 m. Along the axis of the abscissa of the length of the design sections, and along the axis of the ordinate from the end points - pressure losses. By connecting the upper points of these segments, we get a broken one, which will be the piezometric line of the reverse line.

We lay down the necessary located head at the end of the line ΔNab, which is accepted depending on the connection scheme of the subscriber to the thermal network. The obtained section characterizes the head at the end of the supply line. We postpone the head losses upwards, and the supply pipeline ΔNp. We build a piezometric line of the supply line similar to the previous section. We postpone the pressure loss in the boiler CHP up. equal to ΔNb = 10... 20 m. During the initial construction of the piezometric graph, the pressure on the suction side of the network pumps was assumed to be arbitrary. Moving the graph parallel to itself up or down allows you to accept any pressures on the suction side of the network pumps n, respectively, in local systems. However, it should be remembered that when local systems are connected directly, the return pipeline is hydraulically connected to the local system, so the pressure in the return pipeline will be completely transferred to the local system.

When selecting the position of the piezometric graph, the following conditions apply:

The allowable pressure in the return line shall not exceed the allowable operating pressure in local systems.

Pressure in the return pipeline shall be provided by the bay of upper heating system instruments.

Pressure in the return pipeline shall not be lower than

50... 100 kPa to avoid vacuum formation.

The pressure at any point of the supply pipeline shall be higher than the boiling pressure at the maximum design coolant temperature.

The pressure in the suction pipe of the network pumps from the cavitation prevention conditions must be at least 50 kPa and the piezometric head in the return line must be at least 5 m.

The head at the network endpoint should be equal to or greater than the design head loss at the subscriber input during the design coolant flow.

The initial data for hydraulic calculation of heat network pipelines are design heat loads and accepted coolant parameters.

Conclusion

During this course project, the heat supply of the industrial district for the city of Brest was calculated with a given temperature schedule of 150/70 ℃.

To calculate this exchange rate project, climatic data were adopted in accordance with SNB 2.04.02-2000 "Construction climatology." Design ambient temperature for heating design

tno = 21 wasps. Design temperature of external air for design of ventilation of tnv =-8 wasps. Duration of heating period

no = 187 days.

As a result of the calculation of heat consumption by industrial enterprises and residential microdistricts, the maximum total heat consumption to subscribers Q = 53469.6 kW was calculated, including: at GVA QGVA = 10207.4 kW; on ventilation of Qv = 9894.8 kW; for heating

Qo = 33394.3 kW.

The annual schedule of heat consumption for heating, ventilation and hot water supply was built.

The schedule of the central quality regulation of heating load was also built. The outside air temperature at the breaking point of the graph was 4.2 ℃.

The route and profile of the heating network are selected according to the general plan of the industrial district.

In the hydraulic calculation of the water thermal network, the flow rates of network water were determined. Preliminary and calibration calculations of the thermal network were also carried out, where pipe diameters, specific pressure drops and head losses at each section for direct and reverse network water pipelines were determined.

During the hydraulic calculation of the steam pipeline, preliminary and calibration calculations were made, where pressure losses and temperature drop at each of the sections were calculated, and steam pressures and temperatures were also found at the end and beginning of each section. Hydraulic calculation of condensate line is performed similarly to calculations of heat network.

When designing and operating branched thermal networks, a piezometric graph is widely used, on which the terrain, the height of the connected buildings, the head in the network and the head at any point of the network are applied on a specific scale. The piezometric schedule was constructed in accordance with the necessary conditions.

Selection of schemes for connection of heating systems to the thermal network is made based on piezometric graph. In this case, all subscribers join the water heating network according to an independent scheme.

Winter circulation pump supply is 541.3 m3/h, head is 76 m. 2 grade pumps were selected for these parameters.

SCP 200/560 HA200/4 (including 1 standby). Summer circulation pump supply is 88.1 m3/h, head 2 m. For these parameters we accept 2 pumps of BLE 125/185-5.5/4 grade (including 1 standby). We select 2 make-up pumps of Stratos GIGA B 32/151/4.5 grade, including one backup. Select emergency make-up pump of grade

SCP 200/390 HA90/4.

When selecting the type and thickness of the insulation of the heat pipe, the following parameters were defined: the thickness of the main layer of the insulation structure, the coating layer of the insulation was selected, the specific heat loss of the heat wires and the insulation efficiency. Thermal insulation is calculated based on heat loss standards according to SNiP 2.04.1488 "Thermal insulation of equipment and pipelines."

Capital costs for heating system are K = 160506.3 cu. Annual operating costs for network depreciation, repair and maintenance are Sc = 8988.4 ce/year. The cost of electricity for the transfer of coolant in the heating period Se = 13815.3 US/year, and in the inter-heating period Se = 827.2 US/year. The cost of a unit of heat released to consumers is equal in the heating period

S = 0.25 o.e./GJ, and in the interheating period S = 0.80 o.e./GJ.