LCQ11: Coal conveyor belt structures in power stations

Following is a question by Dr Hon Lau Wong-fat and a written reply by the Secretary for Development, Mr Paul Chan, in the Legislative Council today (October 17):


A coal conveyor belt at Castle Peak Power Station of CLP Power Hong Kong Limited, together with its metal frames, collapsed in July this year. In respect of this incident, will the Government inform this Council:

(a) whether it knows the total number of similar metal frames inside the aforesaid power station and their designed service life;

(b) of the government department responsible for monitoring the structural safety of those structures, and whether any inspection has been carried out recently;

(c) of the cause(s) of the incident; and

(d) of the number of similar structures in Hong Kong at present and the procedure adopted by the authorities for monitoring those structures?



On July 25 this year, a section of one of the coal conveyor belts in the Castle Peak Power Station A of CLP Power Hong Kong Limited (CLP) in Tuen Mun came off and fell to the ground. The incident caused no injury and CLP's electricity service was not affected.  After the incident, the Electrical and Mechanical Services Department (EMSD) and the Labour Department (LD) respectively conducted an on-site inspection on July 26 to check on possible concerns over electricity service and occupational safety.

As the metal supporting frames and external casing of the coal conveyor belt are structures, they are subject to the control of the Buildings Ordinance (the Ordinance), the Buildings Department (BD), being the department enforcing the Ordinance, also conducted an on-site inspection on July 31.

My reply to the four-part question is as follows:

(a) The Castle Peak Power Plant in Tuen Mun comprises two power stations, namely Power Station A and Power Station B. The coal conveyor belt in the incident, located in Power Station A, was enclosed in metal casing and supported by five metal frames. One of the metal frames was partly damaged and collapsed in the incident. There are a total of nine sections of similar outdoor elevated coal conveyor belts in the two power stations. The metal supporting frames and external casing of the conveyor belt concerned are regarded as structures, and the materials used in any structures shall be of a suitable nature and quality for the purpose for which they are used. However, it is not appropriate to generalise the service life span of a structure, as it is affected by different factors, such as regular inspection and maintenance.

(b) As mentioned above, the metal supporting frames and external casing of the conveyor belt are structures subject to the control of the Ordinance. Under normal circumstances, BD will conduct on-site inspections and carry out appropriate follow-up actions upon receipt of reports or referrals on the safety of structures. After receiving a referral of this incident, BD staff inspected the structures concerned on July 31 and learned on August 9 that the metal frames damaged in the incident had been removed.

(c) According to our understanding, CLP set up a task force immediately after the incident to identify its causes, restore the facilities as soon as possible and make recommendations to prevent recurrence of similar incidents. CLP has submitted an investigation report to EMSD and LD, and has adopted a number of measures recommended in the report, including carrying out a comprehensive inspection and risk assessment of similar structures in the power plant, adopting an enhanced structural design for new coal conveyor belt structure, and improving the operating procedures for handling of wet coal. The report has also been referred to BD, which is following up the matter with CLP.

CLP has identified several causes of the incident, with the main cause being the exceptionally heavy rainstorm brought by Typhoon Vicente which substantially raised the moisture content of coal beyond the normal level. As the environmental coal that CLP currently uses has a small particle size, it will become slurry after absorbing water, making the handling of wet coal difficult. Despite the abnormally wet coal, the operation of coal transport system had to continue to maintain power generation. This however caused a high coal spillage in the coal conveyor belt. Coupled with some design weaknesses in the coal conveyor belt structure, a section of the conveyor belt structure came off and fell to the ground. CLP considered that the incident was caused by a number of factors and excluded plant aging as one of the reasons for the incident.

(d) According to information provided by CLP and the Hongkong Electric Company Limited, there are a total of 26 similar sections of outdoor elevated coal conveyor belts in power stations across the territory. Regarding the metal supporting frames and external casings of such conveyor belts, as in the case of other structures subject to the control of the Ordinance, it is the responsibility of the owner to build such structures in accordance with the requirements of the Ordinance and carry out regular inspection and timely maintenance to ensure their safety. Upon receipt of any report or referral on structures, BD will take follow-up action in accordance with the Ordinance.

Ends/Wednesday, October 17, 2012
Issued at HKT 14:30