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DL/T 805.4-2016 English PDF (DLT805.4-2016)

DL/T 805.4-2016 English PDF (DLT805.4-2016)

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DL/T 805.4-2016: Guideline for cycle chemistry in fossil plants Part4-feedwater treatment

This part of the DL/T 805 gives the principles and control indicators for the treatment of feedwater during operation and startup of thermal generator set. This part of DL/T 805 is applicable to the feedwater treatment of the steam drum boilers with superheated steam pressures of 3.8 MPa (gauge pressure) and above as well as the direct flow boilers of 5.9 MPa (gauge pressure) and above. This part of the DL/T 805 does not apply to the feedwater treatment of gassteam combined cycle units.
DL/T 805.4-2016
DL
ELECTRIC INDUSTRY STANDARD OF
THE PEOPLE REPUBLIC OF CHINA
ICS 27.100
F 23
Registration number. 53991-2016
Replacing DL/T 805.4-2004
Guideline for cycle chemistry in fossil plants -
Part 4. Feedwater treatment
ISSUED ON. FEBRUARY 05, 2016
IMPLEMENTED ON. JULY 01, 2016
Issued by. National Energy Administration
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 5
4 General ... 6
5 Water treatment methods ... 7
6 Testing methods ... 9
7 Feedwater dosing ... 10
8 Feedwater quality at boiler startup ... 11
9 Treatment when the water quality is degraded ... 12
Foreword
DL/T 805 ?€?Guideline for cycle chemistry in fossil plants?€? is divided into 5 parts. Part 1. Oxygenated treatment for feed-water system of boiler;
Part 2. Phosphate treatment for drum units;
Part 3. Caustic treatment for drum units;
Part 4. Feedwater treatment;
Part 5. All volatile treatment for drum units.
This part is the fourth part of the DL/T 805. As compared with DL/T 805.4-2004, except for editorial changes, the main contents of this revision are as follows. - DELETE ORP terms that are not easily measured accurately.
- ADD testing provisions for chloride ions in feedwater.
- ADD testing provisions for TOCi in feedwater.
- MODIFY the indicators such as hydrogen conductivity, pH, iron, copper and sodium content.
- DELETE the treatment method of OT in the feedwater to the drum boiler having a superheated steam pressure at 12.7 MPa ~ 15.6 MPa.
- ADD the hydrogen conductivity index of feedwater at the start of boiler. This part was written in accordance with the requirements of GB/T 1.1-2009. This part was proposed by the China Electricity Council.
This part shall be under the jurisdiction of the Power Industry Electrical Chemical Standardization Technical Committee.
Drafting organizations of this part. Xi?€?an Thermal Power Research Institute Co., Ltd., Jilin Electric Power Co., Ltd. Electric Power Research Institute. The main drafters of this part. Sun Benda, Zhang Weike, Wang Jiusheng.
This part was first released in October 2004 and this is the first revision. The comments or suggestions on this part in the implementation process are fed back to the China Electricity Council Standardization Management Center (Beijing Baiguang Road Lane 2 No.1, 100761).
Guideline for cycle chemistry in fossil plants -
Part 4. Feedwater treatment
1 Scope
This part of the DL/T 805 gives the principles and control indicators for the treatment of feedwater during operation and startup of thermal generator set. This part of DL/T 805 is applicable to the feedwater treatment of the steam drum boilers with superheated steam pressures of 3.8 MPa (gauge pressure) and above as well as the direct flow boilers of 5.9 MPa (gauge pressure) and above. This part of the DL/T 805 does not apply to the feedwater treatment of gas- steam combined cycle units.
2 Normative references
The following documents are essential to the application of this document. For the dated documents, only the versions with the dates indicated are applicable to this document; for the undated documents, only the latest version (including all the amendments) are applicable to this standard.
GB 536 Liquid anhydrous ammonia
GB/T 631 Chemical reagent - Ammonia
GB/T 6904 Water used in industrial circulating cooling system and boiler - Determination of pH
GB/T 6906 Methods for analysis of water for boiler and for cooling - The determination of hydrazine
GB/T 6909 Analysis of water used in boiler and cooling system -
Determination of hardness
GB/T 12149 Water for industrial circulating cooling system and boiler - Determination of silica
GB/T 12155 Analysis of water used in boiler and cooling system -
Determination for sodium - Dynamic method
GB/T 13689 Water for industrial circulating cooling system and boiler - 3.4
Flow-accelerated corrosion (FAC)
Under specific conditions, the fast corrosion of carbon steel in high speed water flow.
3.5
Feed water system without copper alloys
The feedwater system whose components and equipment coming into
contact with the boiler feedwater do not contain copper or copper alloy. Note. Metal materials contain less than 1% copper and are considered
copper-free materials.
3.6
Feed water supply system with copper alloys
The feedwater system whose components and equipment coming into
contact with the boiler feedwater contain copper or copper alloy.
3.7
Total organic carbonion (TOCi)
The sum of the total carbon content in the organic matter and the other heteroatom content of the anion after oxidation.
4 General
4.1 The water supply treatment method shall be selected in accordance with the material characteristics, furnace type and feed water quality based on the following principles.
a) For feed water system with copper alloys, it should use the AVT(R).
b) For feed water system without copper alloys, it should use the AVT(O). c) For the feed water system without copper alloys which is equipped with condensate polishing device and the feedwater hydrogen conductivity
meets the requirements of feedwater oxygenated treatment, it should use the OT.
4.2 Feedwater treatment shall have the following effects.
of the ammonia addition point, with the distance to the ammonia addition point not less than 50 times the condensate pipe diameter. Its pH is
controlled in the range of 8.8 ~ 9.1. The second ammonia addition point shall be set on the deaerator down-comer, and downstream the deaerator
outlet sampling point, it shall control the pH of the economizer inlet
feedwater in accordance with the provisions of Table 1.
7.1.3 The amount of ammonia added should be controlled in accordance with the conductivity of water after ammonia addition.
7.2 Hydrazine addition
7.2.1 The quality requirements for hydrazine shall be in accordance with HG/T 3259.
7.2.2 The method of adding hydrazine shall be selected in accordance with the following provisions.
a) For the feed water system with copper alloys, the hydrazine addition point should be located at the inlet tube of the shaft seal heater, it shall control the hydrazine content of the feedwater at the deaerator inlet to meet the requirements of Table 1;
b) For the feed water system without copper alloys, the hydrazine addition point should be located at the deaerator down-comer and downstream of
the deaerator outlet sampling point, it shall control the hydrazine content of the feedwater at the economizer inlet to meet the requirements of Table 1.
7.3 Oxygen addition
The oxygen addition to the boiler feedwater shall meet the following
requirements.
a) For the feed water system without copper alloys, it may adopt two-point oxygen addition, they should be located on the condensate fine desalting outlet water main pipe and the deaerator down-comer, respectively, it shall control the dissolved oxygen content of the feedwater at the economizer inlet to comply with the provisions of Table 3;
b) For the feed water system with copper alloys, it should not use oxygenated treatment.
8 Feedwater quality at boiler startup
8.1 When the out-of-service and standby units with AVT(R) and AVT(O) are started, the feedwater treatment shall be the same as in normal operation.

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